Patent Publication Number: US-2022213236-A1

Title: Modified Conjugated Diene-Based Polymer and Rubber Composition Including the Same

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a national phase entry under U.S.C. § 371 of International Application No. PCT/KR2020/012326, filed on Sep. 11, 2020, which claims priority from Korean Patent Application No. 10-2019-0113004, filed on Sep. 11, 2019, and Korean Patent Application No. 10-2020-0116403, filed on Sep. 10, 2020, the entire contents of which are incorporated by reference herein. 
    
    
     TECHNICAL FIELD 
     The present invention relates to a modified conjugated diene-based polymer which has excellent processability and good tensile strength and viscoelasticity properties, and a rubber composition including the same. 
     BACKGROUND ART 
     According to the recent demand for cars having a low fuel consumption ratio, a conjugated diene-based polymer having modulational stability represented by wet skid resistance as well as low rolling resistance, and excellent abrasion resistance and tensile properties is required as a rubber material for tires. 
     In order to reduce the rolling resistance of tires, there is a method of reducing hysteresis loss of vulcanized rubber, and rebound resilience at 50° C. to 80° C., tan 5, Goodrich heating, or the like is used as an evaluation index of the vulcanized rubber. That is, it is desirable to use a rubber material having high rebound resilience at the above temperature or a low tan 5 value or Goodrich heating. 
     Natural rubbers, polyisoprene rubbers, or polybutadiene rubbers are known as rubber materials having low hysteresis loss, but these rubbers have a limitation of low wet skid resistance. Thus, recently, conjugated diene-based polymers or copolymers such as styrene-butadiene rubbers (hereinafter, referred to as “SBR”) and butadiene rubbers (hereinafter, referred to as “BR”), are prepared by emulsion polymerization or solution polymerization to be used as rubbers for tires. Among these polymerization methods, the greatest advantage of the solution polymerization in comparison to the emulsion polymerization is that the vinyl structure content and the styrene content, which specify physical properties of the rubber, may be arbitrarily adjusted and its molecular weight and physical properties may be controlled by coupling or modification. Thus, the SBR prepared by the solution polymerization is widely used as a rubber material for tires because it is easy to change a structure of the finally prepared SBR or BR, and movement of chain terminals may be reduced and a coupling force with a filler such as silica and carbon black may be increased by coupling or modification of the chain terminals. 
     If the solution-polymerized SBR is used as the rubber material for tires, since a glass transition temperature of the rubber is increased by increasing the vinyl content in the SBR, physical properties such as running resistance and braking force, required for tires may be controlled, and fuel consumption may be reduced by appropriately adjusting the glass transition temperature. The solution-polymerized SBR is prepared by using an anionic polymerization initiator and is being used by coupling or modifying the chain terminals of the polymer thus formed to introduce a functional group at the terminal using various modifiers. For example, U.S. Pat. No. 4,397,994 discloses a method of coupling active anions of the chain terminals of a polymer obtained by polymerizing styrene-butadiene using alkyllithium which is a monofunctional initiator in a non-polar solvent, using a coupling agent such as a tin compound. 
     Meanwhile, as the modifier for introducing the functional group to the chain terminal of a polymer, technique of applying an aminoalkoxysilane-based modifier including an alkoxysilane group and an amine group in a molecule at the same time for maximizing the dispersibility and reactivity of a filler is widely known. However, if the number of the amine groups in the modifier increases, there are problems in that the solubility in a hydrocarbon solvent used for preparing a polymer may decrease, and easy modification reaction may become difficult. 
     PRIOR ART DOCUMENT 
     Patent Document 
     (Patent Document 1) US4397994 A 
     DISCLOSURE OF THE INVENTION 
     Technical Problem 
     The present invention has been devised to solve the above-mentioned problems of the conventional technique, and an object is to provide a modified conjugated diene-based polymer suppressing the change of mooney viscosity over time, having excellent affinity with a filler and at the same time, having excellent processability and abrasion resistance through the positioning of a non-functional chain, a derived unit from a modifier, and a N-functional group-rich functional chain. 
     Also, the present invention provides a rubber composition including the modified conjugated diene-based polymer. 
     Technical Solution 
     To solve the above-described tasks, according to an embodiment of the present invention, the present invention provides a modified conjugated diene-based polymer including a derived unit from a modifier including three or more alkoxy groups bonded to silicon; a non-functional chain forming a silicon-carbon bond at one side of the derived unit from a modifier and including a repeating unit derived from a conjugated diene-based monomer; and a functional chain forming a silicon-carbon bond at the other side of the derived unit from a modifier and including two or more derived units from a N-functional group-containing monomer, wherein a rate of change of mooney viscosity (MV R ) according to the following Mathematical Formula 1 is 20% or less: 
       MV R =[(MV f −MV i )/MV i ]×100   [Mathematical Formula 1]
 
     in Mathematical Formula 1, MV R  is the rate of change of mooney viscosity, MV f  is mooney viscosity at 100° C. after standing the polymer at 25° C. for 30 days, and MV i  is initial mooney viscosity of the polymer at 100° C. 
     Also, the present invention provides a rubber composition including the modified conjugated diene-based polymer and a filler. 
     Advantageous Effects 
     The modified conjugated diene-based polymer according to the present invention introduces a functional chain to plentifully distribute functional groups making interaction with a filler and appropriately disposes the functional chain, a derived unit from a modifier, and a non-functional chain, thereby showing excellent affinity with a filler and excellent mechanical properties. 
     Also, the rubber composition according to the present invention includes the modified conjugated diene-based polymer and may show excellent effects of processability as well as tensile properties and viscoelasticity properties, while improving abrasion resistance. 
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     Hereinafter, the present invention will be described in more detail in order to assist the understanding of the present invention. 
     It will be understood that words or terms used in the description and claims of the present invention shall not be interpreted as the meaning defined in commonly used dictionaries, and the words or terms should be interpreted as having a meaning that is consistent with their meaning of the technical idea of the invention, based on the principle that an inventor may properly define the meaning of the words or terms to best explain the invention. 
     Definition of Terms 
     The term “polymer” used in the present disclosure refers to a polymer compound prepared by polymerizing monomers of the same or different type. Thus, the common term, polymer refers to a polymer prepared from only one type of a monomer, but includes a commonly used term of homopolymer and copolymer. 
     The term “functionality” used in the present disclosure may mean inclusion of a functional group and having properties capable of reacting with other functional group or active part, and may mean properties by the inclusion of a functional group including N, O, S or Si in addition to a bond between carbon, or carbon and hydrogen. 
     The term “non-functional chain” used in the present disclosure may mean the molecular chain of a main skeleton forming a polymer, and may mean a chain mainly including the repeating unit of a conjugated diene-based monomer or a conjugated diene-based monomer and an aromatic vinyl-based monomer. 
     The term “vinyl content” used in the present disclosure refers to the mass (or weight) percent of butadiene included in 1 and 2 positions in a polymer chain on the basis of a conjugated diene monomer (butadiene, etc.) moiety in the polymer (on the basis of the total weight of polymerized butadiene). 
     The term “monovalent hydrocarbon group” used in the present disclosure may mean a monovalent atomic group obtained by bonding carbon and hydrogen, in a monovalent alkyl group, alkenyl group, alkynyl group, cycloalkyl group, cycloalkyl group including one or more unsaturated bonds, and aryl group. The minimum carbon number of a substituent represented by the monovalent hydrocarbon may be determined according to the type of each substituent. 
     The term “divalent hydrocarbon group” used in the present disclosure may mean a divalent atomic group obtained by bonding carbon and hydrogen, in a divalent alkylene group, alkenylene group, alkynylene group, cycloalkylene group, cycloalkylene group including one or more unsaturated bonds and arylene group. The minimum carbon number of a substituent represented by the divalent hydrocarbon may be determined according to the type of each substituent. 
     The term “alkyl group” used in the present disclosure may mean monovalent aliphatic saturated hydrocarbon, and may include a linear alkyl group such as methyl, ethyl, propyl and butyl; and a branched alkyl group such as isopropyl, sec-butyl, tert-butyl and neo-pentyl. 
     The term “alkenyl group” used in the present disclosure may mean a monovalent aliphatic unsaturated hydrocarbon including one or two or more double bonds. 
     The term “alkynyl group” used in the present disclosure may mean a monovalent aliphatic unsaturated hydrocarbon including one or two or more triple bonds. 
     The term “alkylene group” used in the present disclosure may mean divalent aliphatic saturated hydrocarbon such as methylene, ethylene, propylene and butylene. 
     The term “aryl group” used in the present disclosure may mean aromatic hydrocarbon, and may include both monocyclic aromatic hydrocarbon in which one ring is formed, and polycyclic aromatic hydrocarbon in which two or more rings are bonded. 
     The term “heterocyclic group” used in the present disclosure is a cycloalkyl group or aryl group in which carbon atoms are substituted with one or more heteroatoms, for example, may include both a heterocycloalkyl group and a heteroaryl group. 
     The term “substituted” used in the present disclosure may mean that the hydrogen of a functional group, an atomic group or a compound is substituted with a specific substituent. If the hydrogen of a functional group, an atomic group or a compound is substituted with a specific substituent, one or a plurality including two or more of substituents may be present according to the number of hydrogen present in the functional group, the atomic group or the compound, and if a plurality of substituents are present, each substituent may be the same or different. 
     The term “single bond” used in the present disclosure may mean a single covalent bond itself excluding a separate atomic or molecular group. 
     The term “derived unit”, “derived repeating unit” and “derived functional group” used in the present disclosure may represent a component or a structure comes from a certain material, or the material itself. 
     It will be further understood that the terms “comprising”, “including”, and “having” and the derivatives thereof in the present disclosure, though these terms are particularly disclosed or not, do not preclude the presence or addition of optional components, steps, or processes. In order to avoid any uncertainty, all components claimed by using the term “comprising” may include additional additives, auxiliaries, or compounds, including a polymer or other materials, unless described to the contrary. In contrast, the term “consisting essentially of -” excludes unnecessary ones for operation and precludes optional other components, steps or processes from the scope of optional explanation. The term “consisting of -” precludes optional components, steps or processes, which are not particularly described or illustrated. 
     Measurement Methods and Conditions 
     In the present disclosure, the “vinyl content” is measured and analyzed using Varian VNMRS 500 MHz NMR, and the 1,2-vinyl bond content in a total polymer is calculated and measured by using 1,1,2,2-tetrachloroethane as a solvent during measuring NMR, and calculating 6.0 ppm as a solvent peak, 7.2-6.9 ppm as random styrene peaks, 6.9-6.2 ppm as block styrene peaks, 5.8-5.1 ppm as 1,4-vinyl and 1,2-vinyl peaks, and 5.1-4.5 ppm as 1,2-vinyl peaks. 
     In the present disclosure, “weight average molecular weight (Mw)”, “number average molecular weight (Mn)”, and “molecular weight distribution (MWD)” are measured through gel permeation chromatography (GPC) analysis and are measured by checking a molecular weight distribution curve. The molecular weight distribution (PDI, MWD, Mw/Mn) is calculated from each molecular weight measured. Particularly, the GPC uses two columns of PLgel Olexis (Polymer laboratories Co.) and one column of PLgel mixed-C (Polymer Laboratories Co.) in combination, and polystyrene (PS) is used as a GPC standard material for calculating the molecular weights, and tetrahydrofuran mixed with 2 wt % of an amine compound is used as a GPC measurement solvent. 
     In the present disclosure, the “N content” may be measured, for example, through an NSX analysis method, and measurement by the NSX analysis method may use a quantitative analyzer of a trace amount of nitrogen (NSX-2100H). For example, in case of using the quantitative analyzer of a trace amount of nitrogen, the quantitative analyzer of a trace amount of nitrogen (Auto sampler, Horizontal furnace, PMT &amp; Nitrogen detector) is turned on, carrier gas flow amounts are set to 250 ml/min for Ar, 350 ml/min for O 2 , and 300 ml/min for ozonizer, a heater is set to 800° C., and the analyzer is stood for about 3 hours for stabilization. After stabilizing the analyzer, a calibration curve of calibration curve ranges of 5 ppm, 10 ppm, 50 ppm, 100 ppm and 500 ppm is made using Nitrogen standard (AccuStandard S-22750-01-5 ml), and an area corresponding to each concentration is obtained. Then, by using the ratios of concentrations to areas, a straight line is made. After that, a ceramic boat holding 20 mg of a specimen is put in the auto sampler of the analyzer and measurement is conducted to obtain an area. By using the area of the specimen thus obtained and the calibration curve, the N content is calculated. In this case, the specimen is a modified conjugated diene-based polymer from which solvents are removed by putting the specimen in hot water heated by steam and stirring, and may be a specimen from which remaining monomers, remaining modifiers and oil are removed. 
     In the present disclosure, the “Si content” is measured using an inductively coupled plasma optical emission spectroscopy (ICP-OES; Optima 7300DV) as an ICP analysis method. Particularly, measurement is performed by adding about 0.7 g of a specimen to a platinum (Pt) crucible, adding about 1 mL of concentrated sulfuric acid (98 wt %, electronic grade) thereto, heating at 300° C. for 3 hours, incinerating the specimen in an electrical furnace (Thermo Scientific, Lindberg Blue M) by the following program of steps 1 to 3: 
     1) step 1: initial temp 0° C., rate (temp/hr) 180° C./hr, temp (holdtime) 180° C. (lhr), 
     2) step 2: initial temp 180° C., rate (temp/hr) 85° C./hr, temp (holdtime) 370° C. (2 hr), and 
     3) step 3: initial temp 370° C., rate (temp/hr) 47° C./hr, temp (holdtime) 510° C. (3 hr), 
     adding 1 mL of concentrated nitric acid (48 wt %) and 20 pl of concentrated hydrofluoric acid (50 wt %) to a residue, sealing the platinum crucible and shaking for 30 minutes or more, adding 1 mL of boric acid to the specimen, storing at 0° C. for 2 hours or more, diluting in 30 ml of ultrapure water, and performing incineration. 
     Modified Conjugated Diene-Based Polymer 
     The present invention provides a modified conjugated diene-based polymer having excellent affinity with a filler, and as a result, capable of providing a rubber composition having excellent processability, tensile properties and viscoelasticity properties. 
     The modified conjugated diene-based polymer according to an embodiment of the present invention includes a derived unit from a modifier including three or more alkoxy groups bonded to silicon; a non-functional chain forming a silicon-carbon bond at one side of the derived unit from a modifier and including a repeating unit derived from a conjugated diene-based monomer; and a functional chain forming a silicon-carbon bond at the other side of the derived unit from a modifier and including two or more derived units from an N-functional group-containing monomer, wherein a rate of change of mooney viscosity (MV R ) according to the following Mathematical Formula 1 is 20% or less: 
       MV R =[(MV f −MV i )/MV i ]100   [Mathematical Formula 1]
 
     in Mathematical Formula 1, MV R  is the rate of change of mooney viscosity, MV f  is mooney viscosity at 100° C. after standing the polymer at 25° C. for 30 days, and MV i  is initial mooney viscosity of the polymer at 100° C. 
     The modified conjugated diene-based polymer has the amount of N atoms in a polymer according to NSX analysis of 100 ppm or more, preferably, 150 ppm or more, more preferably, 170 ppm or more based on a weight. The modified conjugated diene-based polymer introduces a functional chain in which N-functional groups are repeatedly present such that the N atoms may be in the relatively high content, and has a structure in which the N-functional group is bonded to a polymer main chain and a derived unit from an alkoxysilane-based compound bonded to at least one terminal of the main chain. Accordingly, during a compounding process, affinity with a filler, for example, silica and dispersibility may be markedly improved, and viscoelasticity properties may become excellent and at the same time, processability may be largely improved. Meanwhile, for the N content, if an amine-containing alkoxysilane-based modifier is applied, N atoms derived from the modifier may also be present. 
     According to an embodiment of the present invention, the modified conjugated diene-based polymer may have the amount of Si atoms in a polymer according to ICP analysis of 180 ppm or more, preferably, 190 ppm or more, more preferably, 200 ppm or more based on a weight. 
     The Si content may be mainly occupied with Si atoms derived from the modifier which is an alkoxysilane-based compound and may be derived from Si additionally included in the N-functional group-containing monomer in addition to the 
     Si derived from the modifier. The Si content allows the expectation of the increase of the functional groups present in the modified conjugated diene-based polymer, i.e., the improvement of affinity with a filler, and may become an important factor as well as the improvement of processability. 
     In addition, due to such high content of N atoms, the modified conjugated diene-based polymer according to an embodiment of the present invention may satisfy the conditions of the molar ratio (N/Si) of N atoms and Si atoms of 0.75 or more. Generally, a polymer modified by a modifier may include 
     Si atoms and N atoms due to a modification polymerization initiator, a modified monomer, etc., but as described above, since the polymer according to an embodiment of the present invention includes the N-functional group-containing monomer as a repeating unit, the N content may be relatively large, and as consequent symbolic meaning, the molar ratio of the N atoms and the Si atoms may be 0.75 or more, preferably, 0.77 or more, or 0.78 or more, more preferably, 0.8 or more, most optically, 0.9 or more. Through this, the processability improving effects according to the improvement of dispersibility during compounding may be optimized. 
     According to an embodiment of the present invention, the modified conjugated diene-based polymer has the rate of change of mooney viscosity (MV R ) according to Mathematical Formula 1 below of 20% or less. 
       MV R =[(MV f −MV i )/MV i ]100   [Mathematical Formula 1]
 
     In Mathematical Formula 1, MV R  is the rate of change of mooney viscosity, MV f  is mooney viscosity at 100° C. after standing the polymer at 25° C. for 30 days, and MV i  is initial mooney viscosity of the polymer at 100° C. 
     The rate of change of mooney viscosity may be an index for recognizing the increase of mooney viscosity generated during storing after preparation as well as processability. The polymer according to the present invention may show improved processability and furthermore, the low rate of change of mooney viscosity even stored for a long time and excellent storage stability due to structural characteristics in which a functional chain including an N-functional group-containing monomer, a derived unit from a modifier and a non-functional chain of a polymer are bonded in a specific arrangement. 
     The rate of change of mooney viscosity is the rate of change between the initial mooney viscosity of a polymer and the mooney viscosity of the polymer after storing for 30 days at room temperature, and in the present invention, a polymer with 20% or less, preferably, 15% or less is provided. Here, the mooney viscosity is mooney viscosity at 100° C., and may be measured by a common method applied in this technical field. 
     Structure of Modified Conjugated Diene-Based Polymer 
     According to an embodiment of the present invention, the modified conjugated diene-based polymer includes a non-functional chain and a functional chain, and the non-functional chain and the functional chain have an inter-combined structure via the derived unit from a modifier. The non-functional chain and the functional chain are bonded (or coupled) with the derived unit from a modifier as a center, wherein the non-functional chain and the functional chain may be each independently coupled by one or more chains, and preferably, the functional chain may be coupled by two or more chains. 
     The coupling of the functional chain and the non-functional chain with the derived unit from a modifier as a center may be achieved by the reaction between the living anionic terminal of each chain and the Si bond alkoxy group of the modifier. That is, the above-described structure may be achieved through modification reaction and pseudo-modification reaction after polymerization. 
     With the above-described structure, all functional groups may be distributed in one terminal of a polymer, and if making interaction with silica, only one terminal of the polymer may be coupled with the silica, and the other terminal may be in a free state. Accordingly, similar to the conventional single terminal-modified polymer, dispersibility and flocculation prevention of a filler may be excellent, and processability may be excellent. 
     In addition, in the conventional both terminal-modified polymer, functional group-containing monomers are generally coupled with the other terminal different from the derived unit from a modifier, and if such a structure is employed, functional groups may be plentiful, affinity with a filler may be improved, and viscoelasticity properties may be improved, but the degree of freedom of a polymer structure may be largely deteriorated, and processability may be very poor. However, the modified conjugated diene-based polymer according to the present invention has a structure in which the functional chain is adjacent to the derived unit from a modifier, and equal or better degree of interaction with a filler may be achieved, and accordingly, excellent improving effects of viscoelasticity properties may be achieved, and marked improvement of processability may be achieved. 
     In addition, synergistic effects in the interaction with a filler may be generated and abrasion resistance may be largely improved by the presence of the functional chain at the same terminal as the derived unit from a modifier. 
     That is, according to an embodiment of the present invention, the functional chain including the repeating unit derived from an N-functional group-containing monomer and the derived unit from a modifier are positioned at one side in an entire polymer, advantages of the conventional single terminal-modified conjugated diene-based polymer, both terminal-modified conjugated diene-based polymer and enchain-modified conjugated diene-based polymer may be achieved, while solving defects. 
     Non-Functional Chain Including Repeating Unit Derived from Conjugated Diene-Based Monomer 
     According to an embodiment of the present invention, the non-functional chain which is the main skeleton of the modified conjugated diene-based polymer includes a repeating unit derived from a conjugated diene-based monomer as a main unit, and the conjugated diene-based monomer may be, for example, one or more selected from the group consisting of 1,3-butadiene, 2,3-dimethyl-1,3-butadiene, piperylene, 3-butyl-1,3-octadiene, isoprene, 2-phenyl-1,3-butadiene and 2-halo-1,3-butadiene (halo means a halogen atom). 
     In addition, the non-functional chain may include an aromatic vinyl-based monomer and may further include a repeating unit derived therefrom in addition to the conjugated diene-based monomer, and the aromatic vinyl-based monomer may be, for example, one or more selected from the group consisting of styrene, α-methylstyrene, 3-methylstyrene, 4-methylstyrene, 4-propylstyrene, 1-vinylnaphthalene, 4-cyclohexylstyrene, 4-(p-methylphenyl)styrene, 1-vinyl-5-hexylnaphthalene, 3-(2-pyrrolidino ethyl)styrene, 4-(2-pyrrolidinoethyl)styrene and 3-(2-pyrrolidino-1-methyl)-α-methylstyrene. 
     In another embodiment, the non-functional chain of the modified conjugated diene-based polymer may be a copolymer further including a repeating unit derived from a diene-based monomer of 1 to 10 carbon atoms together with the repeating unit derived from the conjugated diene-based monomer. The repeating unit derived from the diene-based monomer may be a repeating unit derived from a diene-based monomer which is different from the conjugated diene-based monomer, and the diene-based monomer which is different from the conjugated diene-based monomer may be, for example, 1,2-butadiene. If the modified conjugated diene-based polymer is a copolymer further including a diene-based monomer, the modified conjugated diene-based polymer may include the repeating unit derived from the diene-based monomer in an amount of greater than 0 wt % to 1 wt %, greater than 0 wt % to 0.1 wt %, greater than 0 wt % to 0.01 wt %, or greater than 0 wt % to 0.001 wt %, and within this range, effects of preventing gel formation may be achieved. 
     According to an embodiment of the present invention, if two or more monomers are included in the non-functional chain which forms the skeleton of the modified conjugated diene-based polymer, the polymer may be a random copolymer chain, and in this case, effects of excellent balance between physical properties may be achieved. The random copolymer may mean the arrangement of repeating units forming a copolymer in disorder. 
     In the non-functional chain of the modified conjugated diene-based polymer according to an embodiment of the present invention, a functional group may not be included, and here, the functional group may be an N-containing functional group, an S-containing functional group, an O-containing functional group, or an Si-containing functional group. By not distributing functional groups in one non-functional chain, effects by disposing the functional chain at one terminal may be achieved. 
     Functional Chain Including Repeating Unit Derived from N-Functional Group-Containing Monomer 
     According to an embodiment of the present invention, the functional chain of the modified conjugated diene-based polymer includes a repeating unit derived from an N-functional group-containing monomer. 
     According to an embodiment of the present invention, the main unit composing the functional chain is the N-function group-containing monomer. The N-functional group may be basically an amino group, an aliphatic cyclic amino group, an aliphatic chain type amino group, an aromatic amino group, etc. 
     In addition, one unit of the functional chain may be coupled with the derived unit from a modifier, and two or more units of the functional chain may be coupled through two or more alkoxysilyl groups present in an alkoxysilyl-based modifier. 
     The functional chain may be a repeatedly bonded type of the N-functional group-containing monomer, and the number of the repeating unit may be 2 to 80. With the number of the repeating units of 2 to 80, the functional groups with a degree desired to obtain by disposing the functional chain on a structure may be secured, and both processability and compounding properties may be achieved. 
     The functional chain may further include a derived unit from a conjugated diene-based monomer. That is, the functional chain may be polymerized (low-polymerized) only with the N-functional-group-containing monomer, but may be prepared by polymerizing (low-polymerizing) the N-functional group-containing monomer and a conjugated diene-based monomer together. In this case, the functional chain may have a random copolymer type in which the conjugated diene-based monomer and the N-functional group-containing monomer are optionally arranged, or a block copolymer type in which the same units are gathered and arranged, and the type is not limited. 
     The weight average molecular weight of the functional chain may be smaller than the weight average molecular weight of the non-functional chain, for example, may be 50% or less, 30% or less, preferably, 20% or less, more preferably, 5% or less of the weight average molecular weight of the non-functional chain. This may be a degree such that the non-functional lchain may be coupled with the residual alkoxy group present in the modifier, and a difference which may overcome the steric hindrance of the non-functional chain modified by or coupled with a modifier may be sufficient, but is not absolutely a standard on the degree of the molecular weight difference. 
     Meanwhile, conventionally, as a method of additionally introducing a functional group to a polymer, a method by which an active polymer is modified by a modifier and then, condensation reaction of reacting a compound which may be condensed with the Si—O bond of the modifier is performed, has been applied. However, if using such condensation reaction, the bond between a material having an additional functional group and a modified polymer may be formed into —Si—O—Si—, and then, there may arise hydrolysis during a step of steam stripping or washing, or storing, and defects of separating a bond at a condensation bond part may arise, and at last, the functional group may lost. 
     On the contrary, in case of the modified conjugated diene-based polymer according to the present invention, the living terminal of the functional chain reacts with the Si—O—R group of the modifier to form a Si—C bond, and there is no fear of separation in that this bond is a bond not undergoing hydrolysis reaction like a condensed bond, and accordingly, storage stability may be improved, and there are not defects of losing initially introduced functional group. 
     According to an embodiment of the present invention, the N-functional group-containing monomer may be, for example, a compound represented by Formula 1 below. 
     
       
         
         
             
             
         
       
     
     In Formula 1, X is N or CH, 
     R 8a  to R 8c  are each independently a hydrogen atom; an alkyl group of 1 to 20 carbon atoms; an alkenyl group of 2 to 20 carbon atoms; an alkynyl group of 2 to 20 carbon atoms; a heteroalkyl group of 1 to 20 carbon atoms, a heteroalkenyl group of 2 to 20 carbon atoms; a heteroalkynyl group of 2 to 20 carbon atoms; a cycloalkyl group of 5 to 20 carbon atoms; an aryl group of 6 to 20 carbon atoms; or a heterocyclic group of 3 to 20 carbon atoms, 
     R 8d  is a single bond, a substituted with a substituent or unsubstituted alkylene group of 1 to 20 carbon atoms; a substituted with a substituent or unsubstituted cycloalkylene group of 5 to 20 carbon atoms; or a substituted with a substituent or unsubstituted arylene group of 6 to 20 carbon atoms, wherein the substituent is an alkyl group of 1 to 10 carbon atoms, a cycloalkyl group of 5 to 10 carbon atoms, or an aryl group of 6 to 20 carbon atoms, 
     R 8e  is an alkyl group of 1 to 20 carbon atoms; an alkenyl group of 2 to 20 carbon atoms; an alkynyl group of 2 to 20 carbon atoms; a heteroalkyl group of 1 to 20 carbon atoms; a heteroalkenyl group of 2 to 20 carbon atoms; a heteroalkynyl group of 2 to 20 carbon atoms; a cycloalkyl group of 5 to 20 carbon atoms; an aryl group of 6 to 20 carbon atoms; a heterocyclic group of 3 to 20 carbon atoms; or a functional group represented by Formula la below, and 
     O is an integer of 0 to 5, at least one R 8e  is a functional group represented by Formula 1a below, and if o is an integer of 2 to 5, multiple R 8e  groups may be the same or different, 
     
       
         
         
             
             
         
       
     
     in Formula 1a, R 8f  is a single bond, a substituted with a substituent or unsubstituted alkylene group of 1 to 20 carbon atoms; a substituted with a substituent or unsubstituted cycloalkylene group of 5 to 20 carbon atoms; or a substituted with a substituent or unsubstituted arylene group of 6 to 20 carbon atoms, wherein the substituent is an alkyl group of 1 to 10 carbon atoms, a cycloalkyl group of 5 to 10 carbon atoms, or an aryl group of 6 to 20 carbon atoms, and 
     R 8g  and R 8h  are each independently an alkyl group of 1 to 20 carbon atoms; an alkenyl group of 2 to 20 carbon atoms; an alkynyl group of 2 to 20 carbon atoms; a heteroalkyl group of 1 to 20 carbon atoms; a heteroalkenyl group of 2 to 20 carbon atoms; a heteroalkynyl group of 2 to 20 carbon atoms; a cycloalkyl group of 5 to 20 carbon atoms; an aryl group of 6 to 20 carbon atoms; a heterocyclic group of 3 to 20 carbon atoms or a mono-substituted, di-substituted or tri-substituted alkylsilyl group with alkyl groups of 1 to 10 carbon atoms, or 
     R 8g  and R 8h  are connected with each other to form a heterocyclic group of 2 to 10 carbon atoms together with N. 
     In addition, the N-functional group-containing monomer may be a compound represented by Formula 2 below. 
     
       
         
         
             
             
         
       
     
     In Formula 2, X 1 —X 2  is CH 2 —CH 2  or CH═CH, and X 3 —X 4  is CH 2 —CH 2 , CH═N or N═N. 
     In addition, the N-functional group-containing monomer may be a compound represented by Formula 3 below. 
     
       
         
         
             
             
         
       
     
     In Formula 3, R 11a  and R 11b  are each independently an alkyl group of 1 to 20 carbon atoms; an alkenyl group of 2 to 20 carbon atoms; an alkynyl group of 2 to 20 carbon atoms; a heteroalkyl group of 1 to 20 carbon atoms; a heteroalkenyl group of 2 to 20 carbon atoms; a heteroalkynyl group of 2 to 20 carbon atoms; a cycloalkyl group of 5 to 20 carbon atoms; 
     an aryl group of 6 to 20 carbon atoms; a heterocyclic group of 3 to 20 carbon atoms; or a functional group represented by Formula 4a below, 
     R 11c  is an alkyl group of 1 to 20 carbon atoms; an alkenyl group of 2 to 20 carbon atoms; an alkynyl group of 2 to 20 carbon atoms; a heteroalkyl group of 1 to 20 carbon atoms, a heteroalkenyl group of 2 to 20 carbon atoms; a heteroalkynyl group of 2 to 20 carbon atoms; a cycloalkyl group of 5 to 20 carbon atoms; an aryl group of 6 to 20 carbon atoms; a heterocyclic group of 3 to 20 carbon atoms; or a functional group represented by Formula 4a below, and 
     at least one of R 11a , R 11b  and R 11c  is a functional group represented by Formula 3a below. 
     
       
         
         
             
             
         
       
     
     In Formula 3a, R 11d  is a single bond, a substituted with a substituent or unsubstituted alkylene group of 1 to 20 carbon atoms; a substituted with a substituent or unsubstituted cycloalkylene group of 5 to 20 carbon atoms; or a substituted with a substituent or unsubstituted arylene group of 6 to 20 carbon atoms, wherein the substituent is an alkyl group of 1 to 10 carbon atoms, a cycloalkyl group of 5 to 10 carbon atoms, or an aryl group of 6 to 20 carbon atoms, and 
     R 11e  and R 11f  are each independently an alkyl group of 1 to 20 carbon atoms; an alkenyl group of 2 to 20 carbon atoms; an alkynyl group of 2 to 20 carbon atoms; a heteroalkyl group of 1 to 20 carbon atoms; a heteroalkenyl group of 2 to 20 carbon atoms; a heteroalkynyl group of 2 to 20 carbon atoms; 
     a cycloalkyl group of 5 to 20 carbon atoms; an aryl group of 6 to 20 carbon atoms; a heterocyclic group of 3 to 20 carbon atoms; or a mono-substituted, di-substituted or tri-substituted alkylsilyl group with alkyl groups of 1 to 10 carbon atoms. 
     In addition, the N-functional group-containing monomer may be a compound represented by Formula 4 below. 
     
       
         
         
             
             
         
       
     
     In Formula 4, R 12a  is a single bond or a substituted with a substituent or unsubstituted alkylene group of 1 to 20 carbon atoms; a substituted with a substituent or unsubstituted cycloalkylene group of 5 to 20 carbon atoms; or a substituted with a substituent or unsubstituted arylene group of 6 to 20 carbon atoms, wherein the substituent is an alkyl group of 1 to 10 carbon atoms, a cycloalkyl group of 5 to 10 carbon atoms, or an aryl group of 6 to 20 carbon atoms, and 
     R 12b  and R 12c  are each independently an alkyl group of 1 to 20 carbon atoms; an alkenyl group of 2 to 20 carbon atoms; an alkynyl group of 2 to 20 carbon atoms; a heteroalkyl group of 1 to 20 carbon atoms; a heteroalkenyl group of 2 to 20 carbon atoms; a heteroalkynyl group of 2 to 20 carbon atoms; a cycloalkyl group of 5 to 20 carbon atoms; an aryl group of 6 to 20 carbon atoms; a heterocyclic group of 3 to 20 carbon atoms; or a mono-substituted, di-substituted or tri-substituted alkylsilyl group with alkyl groups of 1 to 10 carbon atoms. 
     Modifier: alkoxysilane-based compound 
     In addition, the modified conjugated diene-based polymer may have a coupled type of the non-functional chain and the functional chain by the alkoxysilane-based modifier, and the non-functional chain and the functional chain may be coupled using the alkoxysilane-based modifier as a hub. Here, the alkoxysilane-based modifier may include at least three alkoxy groups bonded to Si. 
     According to an embodiment of the present invention, the alkoxysilane-based modifier included in the modified conjugated diene-based polymer may be an amine-containing alkoxysilane-based compound or a non-amine-containing alkoxysilane-based compound. 
     In addition, among the alkoxysilane-based modifier, the amine-containing alkoxysilane-based compound may be, for example, a compound represented by Formula 5 below. 
     
       
         
         
             
             
         
       
     
     In Formula 5, R 1  may be a single bond, or an alkylene group of 1 to 10 carbon atoms, R 2  and R 3  may be each independently an alkyl group of 1 to 10 carbon atoms, R 4  may be hydrogen, an epoxy group, an alkyl group of 1 to 10 carbon atoms, an allyl group of 2 to 10 carbon atoms, a mono-substituted, di-substituted or tri-substituted alkylsilyl group with alkyl groups of 1 to 10 carbon atoms, or a heterocyclic group of 2 to 10 carbon atoms, R 21  may be a single bond, an alkylene group of 1 to 10 carbon atoms, or —[R 42 O] j —, where R 42  may be an alkylene group of 1 to 10 carbon atoms, a and m may be each independently an integer selected from 1 to 3, n may be an integer of 0 to 2, and j may be an integer selected from 1 to 30. 
     In a particular embodiment, the compound represented by Formula 5 may be one selected from the group consisting of N,N-bis(3-(dimethoxy(methyl)silyl)propyl)-methyl-1-amine, N,N-bis(3-(diethoxy(methyl)silyl)propyl)-methyl-1-amine, N,N-bis(3-(trimethoxysilyl)propyl)-methyl-1-amine, N,N-bis(3-(triethoxysilyl)propyl)-methyl-1-amine, tri(trimethoxysilyl)amine, tri-(3-(trimethoxysilyl)propyl)amine, N,N-bis(3-(diethoxy(methyl)silyl)propyl)-1,1,1-trimethlysilanamine, N-(3-(1H-1,2,4-triazole-1-yl)propyl)-3-(trimethoxysilyl)-N-(3-(trimethoxysilyl)propyl)propan-1-amine, 3-(trimethoxysilyl)-N-(3-(trimethoxysilyl)propyl)-N-(3-(1-(3-(trimethoxysilyl)propyl)-1H-1,2,4-triazol-3-yl)propyl)propan-1-amine, N-allyl-N-(3-(trimethoxysilyl)propyl)prop-2-en-1-amine), N,N-bis(oxiran-2-ylmethyl)-3-(trimethoxysilyl)propan-1-amine, 1,1,1-trimethyl-N-(3-(triethoxysilyl)propyl)-N-(trimethylsilyl)silanamine) and N,N-bis(3-(triethoxysilyl)propyl)-2,5,8,11,14-pentaoxahexadecan-16-amine. 
     In another embodiment, among the alkoxysilane-based modifier, the amine-containing alkoxysilane-based compound may include a compound represented by Formula 6 below. 
     
       
         
         
             
             
         
       
     
     In Formula 6, R 5 , R 6  and R 9  may be each independently an alkylene group of 1 to 10 carbon atoms, R 7 , R 8 , R 10  and R 11  may be each independently an alkyl group of 1 to 10 carbon atoms, R 12  may be hydrogen or an alkyl group of 1 to 10 carbon atoms, b and c may be each independently 1, 2 or 3, where b+c≥4 may be satisfied, and A may be 
     
       
         
         
             
             
         
       
     
     where R 13 , R 14 , R 15  and R 16  may be each independently hydrogen or an alkyl group of 1 to 10 carbon atoms. 
     In a particular embodiment, the compound represented by Formula 6 may be one selected from the group consisting of N-(3-(1H-imidazol-1-yl)propyl)-3-(triethoxysilyl)-N-(3-(triethoxysilyl)propyl)propan-1-amine and 3-(4,5-dihydro-1H-imidazol-1-yl)-N,N-bis(3-(triethoxysilyl)propyl)propan-1-amine. 
     In another embodiment, among the alkoxysilane-based modifier, the amine-containing alkoxysilane-based compound may include a compound represented by Formula 7 below. 
     
       
         
         
             
             
         
       
     
     In Formula 7, A′ and A 2  may be each independently a divalent hydrocarbon group of 1 to 20 carbon atoms, which contains an oxygen atom or not, R 17  to R 20  may be each independently a monovalent hydrocarbon group of 1 to 20 carbon atoms, L 1  to L 4  may be each independently a mono-substituted, di-substituted or tri-substituted alkylsilyl group with alkyl groups of 1 to 10 carbon atoms, or a monovalent hydrocarbon group of 1 to 20 carbon atoms, wherein L 1  and L 2 , and L 3  and L 4  may be combined with each other to form rings of 1 to 5 carbon atoms, and if L 1  and L 2 , and L 3  and L 4  are combined with each other to form rings, the rings thus formed may include one or more heteroatoms selected from the group consisting of N, O and S. 
     In a particular embodiment, the compound represented by Formula 7 may be one selected from the group consisting of 3,3′-(1,1,3,3-tetramethoxydisiloxane-1,3-diyl)bis(N,N-dimethylpropan-1-amine, 3,3′-(1,1,3,3-tetraethoxydisiloxane-1,3-diyl)bis(N,N-dimethylpropan-1-amine), 3,3′-(1,1,3,3-tetrapropoxydisiloxane-1,3-diyl)bis(N,N-dimethylpropan-1-amine), 3,3′-(1,1,3,3-tetramethoxydisiloxane-1,3-diyl)bis(N,N-diethylpropan-1-amine), 3,3′-(1,1,3,3-tetramethoxydisiloxane-1,3-diyl)bis(N,N-dimpropylpropan-1-amine), 3,3′-(1,1,3,3-tetraethoxydisiloxane-1,3-diyl)bis(N,N-diethylpropan-1-amine), 3,3′-(1,1,3,3-tetrapropoxydisiloxane-1,3-diyl)bis(N,N-diethylpropan-1-amine), 3,3′-(1,1,3,3-tetraethoxydisiloxane-1,3-diyl)bis(N,N-dipropylpropan-1-amine), 3,3′-(1,1,3,3-tetrapropoxydisiloxane-1,3-diyl)bis(N,N-dipropylpropan-1-amine), 3,3′-(1,1,3,3-tetramethoxydisiloxane-1,3-diyl)bis(N,N-diethylmethan-1-amine), 3,3′-(1,1,3,3-tetraethoxydisiloxane-1,3-diyl)bis(N,N-diethylmethan-1-amine), 3,3′-(1,1,3,3-tetrapropoxydisiloxane-1,3-diyl)bis(N,N-diethylmethan-1-amine), 3,3′-(1,1,3,3-tetramethoxydisiloxane-1,3-diyl)bis(N,N-dimethylmethan-1-amine), 3,3′-(1,1,3,3-tetramethoxydisiloxane-1,3-diyl)bis(N,N-dipropylmethan-1-amine), 3,3′-(1,1,3,3-tetrapropoxydisiloxane-1,3-diyl)bis(N,N-dimethylmethan-1-amine), 3,3′-(1,1,3,3-tetrapropoxydisiloxane-1,3-diyl)bis(N,N-dipropylmethan-1-amine), 3,3′-(1,1,3,3-tetraethoxydisiloxane-1,3-diyl)bis(N,N-dimethylmethan-1-amine), 3,3′-(1,1,3,3-tetraethoxydisiloxane-1,3-diyl)bis(N,N-dipropylmethan-1-amine), N,N′-((1,1,3,3-tetramethoxydisiloxane-1,3-diyl)bis(propan-3,1-diyl))bis(1,1,1-trimethyl-N-(trimethylsilyl)silanamine, N,N′-((1,1,3,3-tetraethoxydisiloxane-1,3-diyl)bis(propan-3,1-diyl))bis(1,1,1-trimethyl-N-(trimethylsilyl)silanamine, N,N′-((1,1,3,3-tetrapropoxydisiloxane-1,3-diyl)bis(propan-3,1-diyl))bis(1,1,1-trimethyl-N-(trimethylsilyl)silanamine, N,N′-((1,1,3,3-tetramethoxydisiloxane-1,3-diyl)bis(propan-3,1-diyl))bis(1,1,1-trimethyl-N-phenylsilanamine, N,N′-((1,1,3,3-tetraethoxydisiloxane-1,3-diyl)bis(propan-3,1-diyl))bis(1,1,1-trimethyl-N-phenylsilanamine, N,N′-((1,1,3,3-tetrapropoxydisiloxane-1,3-diyl)bis(propan-3,1-diyl))bis(1,1,1-trimethyl-N-phenylsilanamine, 1,3-bis(3-(1H-imidazol-1-yl)propyl)-1,1,3,3-tetramethoxydisiloxane, 1,3-bis(3-(1H-imidazol-1-yl)propyl)-1,1,3,3-tetraethoxydisiloxane, and 1,3-bis(3-(1H-imidazol-1-yl)propyl)-1,1,3,3-tetrapropoxydisiloxane. 
     In another embodiment, among the alkoxysilane-based compound, the amine-containing alkoxysilane-based compound may include a compound represented by Formula 8 below. 
     
       
         
         
             
             
         
       
     
     In Formula 8, R b2  to R b4  are each independently an alkylene group of 1 to 10 carbon atoms, R b5  to R b8  are each independently an alkyl group of 1 to 10 carbon atoms, R b13  and R b14  are each independently an alkylene group of 1 to 10 carbon atoms, R b15  to R b18  are each independently an alkyl group of 1 to 10 carbon atoms, and m1, m2, m3 and m4 are each independently an integer of 1 to 3. 
     In another embodiment, among the alkoxysilane-based compound, the amine-containing alkoxysilane-based compound may include a compound represented by Formula 9 below. 
     
       
         
         
             
             
         
       
     
     In Formula 9, R e1  and R e2  are each independently an alkylene group of 1 to 10 carbon atoms, R e3  to R e6  are each independently hydrogen, an alkyl group of 1 to 10 carbon atoms or —R e7 SiR e8 R e9 R e10 , where at least one among R e3  to R e6  is —R e7 SiR e8 R e9 R e10 , wherein R ef  is a single bond or an alkylene group of 1 to 10 carbon atoms, R e8  to R eio  are each independently an alkyl group of 1 to 10 carbon atoms or an alkoxy group of 1 to 10 carbon atoms, where at least one among R e8  to R e10  is an alkoxy group of 1 to 10 carbon atoms. 
     In another embodiment, among the alkoxysilane-based compound, the non-amine-containing alkoxysilane-based compound may include a compound represented by Formula 10 below. 
     
       
         
         
             
             
         
       
     
     In Formula 10, X is O or S, R f1  and R f2  are each independently a single bond or an alkylene group of 1 to 10 carbon atoms, 
     R f3  to R f8  are each independently hydrogen, an alkyl group of 1 to 10 carbon atoms, an alkoxy group of 1 to 10 carbon atoms, an aryl group of 6 to 10 carbon atoms, a cycloalkyl group of 5 to 10 carbon atoms or an aralkyl group of 7 to 14 carbon atoms, and p is an integer of 0 or 1, where if p is 0, R f1  is an alkyl group of 1 to 10 carbon atoms or an alkoxy group of 1 to 10 carbon atoms. 
     In another embodiment, among the alkoxysilane-based compound, the non-amine-containing alkoxysilane-based compound may include a compound represented by Formula 11 below. 
     
       
         
         
             
             
         
       
     
     In Formula 11, R g1  to R g4  are each independently hydrogen, an alkyl group of 1 to 10 carbon atoms, an alkoxy group of 1 to 10 carbon atoms, an aryl group of 6 to 12 carbon atoms or —R g5 SiOR g6 ), where at least one among R g1  to R g4  is —R g5 SiOR g6 , wherein R g5  is a single bond or an alkylene group of 1 to 10 carbon atoms, R g6  is an alkyl group of 1 to 10 carbon atoms, and Y is C or N, where if Y is N, R g4  is not present. 
     In another embodiment, among the alkoxysilane-based compound, the amine-containing alkoxysilane-based compound may include a compound represented by Formula 12 below. 
     
       
         
         
             
             
         
       
     
     In Formula 12, R h1  and R h2  are each independently an alkyl group of 1 to 10 carbon atoms or an alkoxy group of 1 to 10 carbon atoms, R h3  is a single bond or an alkylene group of 1 to 10 carbon atoms, and A 3  is —Si (R h4 R h5 R h6 ) or —N [Si (R h7 R h8 R h9 )] 2 , where R h4  to R h9  are each independently an alkyl group of 1 to 10 carbon atoms or an alkoxy group of 1 to 10 carbon atoms. 
     In another embodiment, among the alkoxysilane-based compound, the non-amine-containing alkoxysilane-based compound may be a compound represented by Formula 13 below. 
     
       
         
         
             
             
         
       
     
     In Formula 13, R g1  to R g3  are each independently an alkyl group of 1 to 10 carbon atoms or an alkoxy group of 1 to 10 carbon atoms, R g4  is an alkoxy group of 1 to 10 carbon atoms, and q is an integer of 2 to 100. 
     General Details 
     The modified conjugated diene-based polymer according to an embodiment of the present invention may have a number average molecular weight (Mn) of 1,000 g/mol to 2,000,000 g/mol, 10,000 g/mol to 1,000,000 g/mol, or 100,000 g/mol to 800,000 g/mol, a weight average molecular weight (Mw) of 1,000 g/mol to 3,000,000 g/mol, 10,000 g/mol to 2,000,000 g/mol, or 100,000 g/mol to 2,000,000 g/mol, and a peak average molecular weight (Mp) of 1,000 g/mol to 3,000,000 g/mol, 10,000 g/mol to 2,000,000 g/mol, or 100,000 g/mol to 2,000,000 g/mol. Within the ranges, excellent effects of rolling resistance and wet skid resistance may be achieved. In another embodiment, the modified conjugated diene-based polymer may have molecular weight distribution (PDI; MWD; Mw/Mn) of 1.0 to 3.0, or 1.1 to 2.5, or 1.1 to 2.0, and within this range, excellent effects of tensile properties, viscoelasticity properties, and balance between physical properties may be achieved, 
     Also, the modified conjugated diene-based polymer may have a mooney viscosity at 100° C. of 30 or more, 40 to 150, or to 140, and within this range, excellent effects of processability and productivity may be achieved. 
     Here, the mooney viscosity may be measured using a mooney viscometer. Particularly, the mooney viscosity may be measured by using MV-2000E of Monsanto Co. using Large Rotor at a rotor speed of 2±0.02 rpm at 100° C. In this case, a polymer was stood at room temperature (23±3° C.) for 30 minutes or more, and 27±3 g of the polymer was collected and put in a die cavity, and then, Platen was operated while applying torque for measurement. 
     In addition, the vinyl content in the modified conjugated diene-based polymer may be 5 wt % or more, 10 wt % or more, or 10 wt % to 60 wt %. Here, the vinyl content may mean the amount of not 1,4-added but 1,2-added conjugated diene-based monomer with respect to 100 wt % of a conjugated diene-based copolymer composed of a monomer having a vinyl group and an aromatic vinyl-based monomer. 
     Method for Preparing Modified Conjugated Diene-Based Polymer 
     In addition, the present invention provides a method for preparing a modified conjugated diene-based polymer. 
     The method for preparing a modified conjugated diene-based polymer according to an embodiment of the present invention is characterized in including polymerizing a conjugated diene-based monomer, or a conjugated diene-based monomer and an aromatic vinyl-based monomer in the presence of a polymerization initiator in a hydrocarbon solvent to prepare an active non-functional chain (S1); reacting the active non-functional chain with an alkoxysilane-based modifier to prepare a modified active non-functional chain (S2); and reacting the modified active non-functional chain and a functional chain including a repeating unit derived from an N-functional group-containing monomer (S3). 
     The hydrocarbon solvent is not specifically limited, but may be, for example, one or more selected from the group consisting of n-pentane, n-hexane, n-heptane, isooctane, cyclohexane, toluene, benzene and xylene. 
     The polymerization initiator is not specifically limited, but may be, for example, one or more selected from the group consisting of methyllithium, ethyllithium, propyllithium, isopropyllithium, n-butyllithium, s-butyllithium, t-butyllithium, hexyllithium, n-decyllithium, t-octyllithium, phenyllithium, 1-naphthyl lithium, n-eicosyl lithium, 4-butylphenyl lithium, 4-tolyl lithium, cyclohexyl lithium, 3,5-di-n-heptylcyclohexyl lithium, 4-cyclopentyl lithium, naphthyl sodium, naphthyl potassium, lithium alkoxide, sodium alkoxide, potassium alkoxide, lithium sulfonate, sodium sulfonate, potassium sulfonate, lithium amide, sodium amide, potassium amide, and lithium isopropylamide. 
     According to an embodiment of the present invention, the polymerization initiator may be used in 0.01 mmol to 10 mmol, 0.05 mmol to 5 mmol, 0.1 mmol to 2 mmol, 0.1 mmol to 1 mmol, or 0.15 to 0.8 mmol based on total 100 g of the monomer. Here, 100 g of the monomer may represent the total amount of the conjugated diene-based monomer, or the conjugated diene-based monomer and the aromatic vinyl-based monomer. 
     S1 Step 
     The polymerization of step (S1) may be, for example, an anionic polymerization, and particularly, a living anionic polymerization by which an anionic active part is included at the polymerization terminal through a propagation polymerization reaction by anions. In addition, the polymerization of step (S1) may be a polymerization with heating, an isothermal polymerization, or a polymerization at a constant temperature (adiabatic polymerization). Here, the polymerization at a constant temperature means a polymerization method including a step of polymerizing using self-generated heat of reaction without optionally applying heat after adding a polymerization initiator, and the polymerization with heating means a polymerization method including injecting the polymerization initiator and then, increasing the temperature by optionally applying heat. The isothermal polymerization means a polymerization method by which the temperature of a polymer is kept constant by increasing heat by applying heat or taking heat after adding the polymerization initiator. 
     In addition, according to an embodiment of the present invention, the polymerization of step (S1) may be performed by further adding a diene-based compound of 1 to 10 carbon atoms in addition to the conjugated diene-based monomer, and in this case, effects of preventing the formation of gel on the wall of a reactor during operation for a long time may be achieved. The diene-based compound may be, for example, 1,2-butadiene. 
     The polymerization of step (S1) may be performed in a temperature range of, for example, 80° C. or less, -20° C. to 80° C., 0° C. to 80° C., 0° C. to 70° C., or 10° C. to 70° C., and within the range, the molecular weight distribution of a polymer is controlled narrow, and the improving effects of physical properties were excellent. 
     The active main chain prepared by step (S1) may mean a polymer in which a polymer anion and an organometallic cation are coupled. 
     Meanwhile, the polymerization of step (S1) may be performed by including a polar additive, and the polar additive may be added in a ratio of 0.001 g to 50 g, 0.001 g to 10 g or 0.005 g to 0.1 g based on total 100 g of the monomer. In another embodiment, the polar additive may be added in a ratio of 0.001 g to 10 g, 0.005 g to 5 g, 0.005 g to 4 g based on total 1 mmol of the polymerization initiator. 
     The polar additive may be, for example, one or more selected from the group consisting of tetrahydrofuran, 2,2-di(2-tetrahydrofuryl)propane, diethyl ether, cyclopentyl ether, dipropyl ether, ethylene methyl ether, ethylene dimethyl ether, diethyl glycol, dimethyl ether, tert-butoxy ethoxy ethane, bis(3-dimethylaminoethyl)ether, (dimethylaminoethyl) ethyl ether, trimethylamine, triethylamine, tripropylamine, 
     N,N,N′,N′-tetramethylethylenediamine, sodium mentholate and 2-ethyl tetrahydrofufuryl ether, preferably, 2,2-di(2-tetrahydrofuryl) propane, triethylamine, tetramethylethylenediamine, sodium mentholate or 2-ethyl tetrahydrofufuryl ether. If the polar additive is included, and if a conjugated diene-based monomer and an aromatic vinyl-based monomer are copolymerized, the difference of their reaction rates may be compensated, and effects of inducing easy formation of a random copolymer may be achieved. 
     S2 Step 
     The (S2) step is a step of reacting the active non-functional chain with an alkoxysilane-based compound to prepare a modified active non-functional chain, and here, the reaction may be modification or coupling reaction, and in this case, the modifier may be used in an amount of 0.01 mmol to 10 mmol based on total 100 g of the monomer. In another embodiment, the modifier may be used in a molar ratio of 1:0.1 to 10, 1:0.1 to 5, or 1:0.1 to 1:3, based on 1 mol of the polymerization initiator in step (S1). 
     S3 Step 
     In addition, the (S3) step is a step of reacting the modified active non-functional chain with a functional chain including the repeating unit derived from an N-functional group-containing monomer to prepare a modified conjugated diene-based polymer. 
     Meanwhile, the preparation method according to an embodiment of the present invention may further include a step of preparing a functional chain prior to the (S3) step, and the step of preparing the functional chain may be performed by performing polymerization reaction of an N-functional group-containing monomer, or an N-functional group-containing monomer and a conjugated diene-based monomer in the presence of an organolithium compound in a hydrocarbon solvent. In this case, the polymerization reaction may be a living anionic polymerization to give an anionic active part at the polymerization terminal by the propagation polymerization reaction by anions, and the functional chain may be a living anion terminal of which one terminal is capable of acting as a monomer. 
     Here, the organolithium compound may be an alkyllithium compound, and may particularly be methyllithium, ethyllithium, propyllithium, isopropyllithium, n-butyllithium, s-butyllithium, t-butyllithium, hexyllithium, n-decyllithium, t-octyllithium, phenyllithium, 1-naphthyl lithium, n-eicosyl lithium, 4-butylphenyl lithium, 4-tolyl lithium, cyclohexyl lithium, 3,5-di-n-heptylcyclohexyl lithium, or 4-cyclopentyl lithium, more particularly, n-butyllithium. 
     In an embodiment, the functional chain may be prepared through Reaction 1 below and may be a compound having a structure represented by Formula Ml below. 
     
       
         
         
             
             
         
       
     
     In another embodiment, the functional chain may be prepared through Reaction 2 below and may be a compound having a structure represented by Formula M2 below. 
     
       
         
         
             
             
         
       
     
     In another embodiment, the functional chain may be prepared through Reaction 3 below and may be a compound having a structure represented by Formula M3 below. 
     
       
         
         
             
             
         
       
     
     In another embodiment, the functional chain may be prepared through Reaction 4 below and may be a compound having a structure represented by Formula M4 below. 
     
       
         
         
             
             
         
       
     
     In Reaction 1 to Reaction 4, R 8d , R 8 , X, X 1 —X 2 , X 3 —X 4 , R 11a  to R 11c , R 12a  to R 12c , and o are the same as defined in Formula 1 to Formula 4, R—Li is an alkyllithium compound, and R is an alkyl group derived from the alkyllithium. 
     In addition, the functional chain may include 1 to 80, to 60, or 1 to 50 repeating units derived from the N-functional group-containing monomer selected from the compounds represented by Formula 1 to Formula 4, and for example, in Formula Ml to Formula M4, each of r 1  to r 4  may be 1 to 80, 1 to 60, or 1 to 50. In this case, the modified conjugated diene-based polymer including a sub chain derived from the functional chain may have the above-described Si and N contents and may have excellent processability, tensile properties and viscoelasticity properties in balance. 
     Meanwhile, the (S3) step may be for preparing a modified conjugated diene-based polymer by reacting the modified active polymer and the functional chain, i.e., the functional group derived from a modifier in the modified active polymer and the living anion terminal of the functional chain. 
     Particularly, the modified active polymer main chain prepared in the (S2) step includes the functional group derived from a modifier, and the functional group derived from a modifier includes an alkoxy group not reacted with a polymer chain but remaining, and accordingly, through the reaction of the living anion terminal of the functional chain and the alkoxy group, the modified conjugated diene-based polymer may be prepared. 
     In addition, the functional chain may use in 0.1 to 4.0 mol, 0.1 to 2.0 mol, or 0.5 to 1.5 mol based on 1 mol of the polymerization initiator. 
     In case of applying the preparation method according to an embodiment of the present invention, there are advantages of introducing more functional groups than a case of using only a modifier having a large number of functional groups. Particularly, to the active polymer and the alkoxy group of the modifier, it is difficult that two or more polymer chains may be bonded to one molecule of the modifier due to the steric hindrance of a polymer, and a modified polymer coupled with three or more chains may be possible but a small amount. However, as in the present invention, a functional chain having the weight average molecular weight by about 10% level of the non-functional chain may overcome steric hindrance effects, and accordingly, may be bonded to the alkoxy residual group of the modifier to which one or two non-functional chains are bonded, and more functional groups may be introduced to a polymer chain. 
     That is, the introduction of a functional group in one molecule of a modifier is definitely limited, and no matter how many functional groups are introduced, there must be an absolute amount difference when compared with a case of coupling the functional chain with an alkoxy residual group to a degree not affected by steric hindrance effects as in the present invention. 
     Accordingly, the modified conjugated diene-based polymer prepared by the preparation method of the modified conjugated diene-based polymer according to the present invention may have better tensile properties and viscoelasticity properties in contrast to the conventional single terminal-modified polymer. In addition, in view of a method utilizing an alkoxy residual group, non-functional properties may be maintained at the terminal for additional introduction of a functional group, and processability properties may be markedly improved in contrast to the conventional both terminal-modified polymer. In addition, the alkoxy residual group remaining in the derived unit from a modifier may be reduced when compared with the conventional preparation method, and side reactions such as condensation reaction and hydrolysis reaction performed due to the presence of a —OR group or a —OH group in a polymer may be markedly reduced, and accordingly, processability may be improved, a change with the passage of time may be markedly reduced, and storage stability may also be improved. 
     Rubber Composition 
     Also, the present invention provides a rubber composition including the modified conjugated diene-based polymer. 
     The rubber composition may include the modified conjugated diene-based polymer in an amount of 10 wt % or more, 10 wt % to 100 wt %, or 20 wt % to 90 wt %, and within this range, mechanical properties such as tensile strength and abrasion resistance are excellent, and effects of excellent balance between physical properties may be achieved. 
     In addition, the rubber composition may further include other rubber component, as necessary, in addition to the modified conjugated diene-based polymer, and in this case, the rubber component may be included in an amount of 90 wt % or less based on the total weight of the rubber composition. In a particular embodiment, the rubber component may be included in an amount of 1 part by weight to 900 parts by weight based on 100 parts by weight of the modified conjugated diene-based polymer. 
     The rubber component may be, for example, a natural rubber or a synthetic rubber, and may particularly be a natural rubber (NR) including cis-1,4-polyisoprene; a modified natural rubber which is obtained by modifying or purifying a common natural rubber, such as an epoxidized natural rubber (ENR), a deproteinized natural rubber (DPNR), and a hydrogenated natural rubber; and a synthetic rubber such as a styrene-butadiene copolymer (SBR), a polybutadiene (BR), a polyisoprene (IR), a butyl rubber (IIR), an ethylene-propylene copolymer, a polyisobutylene-co-isoprene, a neoprene, a poly(ethylene-co-propylene), a poly(styrene-co-butadiene), a poly(styrene-co-isoprene), a poly(styrene-co-isoprene-co-butadiene), a poly(isoprene-co-butadiene), a poly(ethylene-co-propylene-co-diene), a polysulfide rubber, an acryl rubber, a urethane rubber, a silicone rubber, an epichlorohydrin rubber, a butyl rubber, and a halogenated butyl rubber, and any one among them or mixtures of two or more thereof may be used. 
     The rubber composition may include a filler of 0.1 parts by weight to 200 parts by weight, or 10 parts by weight to 120 parts by weight based on 100 parts by weight of the modified conjugated diene-based polymer of the present invention. The filler may be, for example, a silica-based filler, particularly, wet silica (hydrated silicate), dry silica (anhydrous silicate), calcium silicate, aluminum silicate, or colloid silica. Preferably, the filler may be wet silica which has the most significant improving effect of destruction characteristics and compatible effect of wet grip. In addition, the rubber composition may further include a carbon-based filler, as necessary. 
     In another embodiment, if silica is used as the filler, a silane coupling agent may be used together for the improvement of reinforcing and low exothermic properties. Particular examples of the silane coupling agent may include bis(3-triethoxysilylpropyl)tetrasulfide, bis(3-triethoxysilylpropyl)trisulfide, bis(3-triethoxysilylpropyl) disulfide, bis(2-triethoxysilylethyl)tetrasulfide, bis(3-trimethoxysilylpropyl)tetrasulfide, bis(2-trimethoxysilylethyl)tetrasulfide, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, 3-trimethoxysilylpropyl-N,N-dimethylthiocarbamoyltetrasulfide, 3-triethoxysilylpropyl-N,N-dimethylthiocarbamoyltetrasulfide, 2-triethoxysilylethyl-N,N-dimethylthiocarbamoyltetrasulfide, 3-trimethoxysilylpropylbenzothiazolyltetrasulfide, 3-triethoxysilylpropylbenzolyltetrasulfide, 3-triethoxysilylpropylmethacrylatemonosulfide, 3-trimethoxysilylpropylmethacrylatemonosulfide, bis(3-diethoxymethylsilylpropyl)tetrasulfide, 3-mercaptopropyldimethoxymethylsilane, dimethoxymethylsilylpropyl-N,N-dimethylthiocarbamoyltetrasulfide, or dimethoxymethylsilylpropylbenzothiazolyltetrasulfide, and any one among them or mixtures of two or more thereof may be used. 
     Preferably, bis(3-triethoxysilylpropyl)polysulfide or 3-trimethoxysilylpropylbenzothiazyltetrasulfide may be used in consideration of the improving effect of reinforcing properties. 
     In addition, in the rubber composition according to an embodiment of the present invention, since a modified conjugated diene-based polymer in which a functional group having high affinity with silica is introduced into an active part is used as a rubber component, the compounding amount of the silane coupling agent may be smaller than a common case. 
     Thus, the silane coupling agent may be used in an amount of 1 part by weight to 20 parts by weight, or 5 parts by weight to 15 parts by weight based on 100 parts by weight of silica. Within the above amount range, effects as a coupling agent may be sufficiently exhibited, and preventing effects of gelation of a rubber component may be achieved. 
     The rubber composition according to an embodiment of the present invention may be sulfur crosslinkable, and so may further include a vulcanizing agent. The vulcanizing agent may particularly be a sulfur powder and may be included in an amount of 0.1 parts by weight to 10 parts by weight based on 100 parts by weight of the rubber component. Within the above amount range, elasticity and strength required for a vulcanized rubber composition may be secured, and at the same time, an excellent low fuel consumption ratio may be achieved. 
     The rubber composition according to an embodiment of the present invention may further include various additives used in a common rubber industry in addition to the above components, particularly, a vulcanization accelerator, a process oil, an antioxidant, a plasticizer, an antiaging agent, a scorch preventing agent, a zinc white, stearic acid, a thermosetting resin, or a thermoplastic resin. 
     The vulcanization accelerator may include, for example, thiazole-based compounds such as 2-mercaptobenzothiazole (M), dibenzothiazyldisulfide (DM), and N-cyclohexyl-2-benzothiazylsulfenamide (CZ), or guanidine-based compounds such as diphenylguanidine (DPG), in an amount of 0.1 parts by weight to 5 parts by weight based on 100 parts by weight of the rubber component. 
     The process oil acts as a softener in a rubber composition and may include, for example, a paraffin-based, naphthene-based, or aromatic compound. An aromatic process oil may be used in consideration of tensile strength and abrasion resistance, and a naphthene-based or paraffin-based process oil may be used in consideration of hysteresis loss and properties at a low temperature. The process oil may be included in an amount of 100 parts by weight or less based on 100 parts by weight of the rubber component. Within the above-described range, the deterioration of the tensile strength and low exothermic properties (low fuel consumption ratio) of the vulcanized rubber may be prevented. 
     The antioxidant may include, for example, 2,6-di-t-butyl paracresol, dibutylhydroxytoluene, 2,6-bis((dodecylthio)methyl)-4-nonylphenol or 2-methyl-4,6-bis((octylthio)methyl)phenol, and may be used in an amount of 0.1 parts by weight to 6 parts by weight based on 100 parts by weight of the rubber component. 
     The antiaging agent may include, for example, N-isopropyl-N′-phenyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine, 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline, or a condensate of diphenylamine and acetone at a high temperature, in an amount of 0.1 parts by weight to 6 parts by weight based on 100 parts by weight of the rubber component. 
     The rubber composition according to an embodiment of the present invention may be obtained by mulling using a mulling apparatus such as a banbury mixer, a roll, and an internal mixer according to a compounding prescription. A rubber composition having low exothermic properties and good abrasion properties may be obtained by a vulcanization process after a molding process. 
     Therefore, the rubber composition may be useful to the manufacture of each member of a tire such as a tire tread, an under tread, a side wall, a carcass coating rubber, a belt coating rubber, a bead filler, a chafer, and a bead coating rubber, or to the manufacture of rubber products in various industries such as a vibration-proof rubber, a belt conveyor, and a hose. 
     Also, the present invention provides a tire manufactured using the rubber composition. 
     The tire may include a tire or a tire tread. 
     EXAMPLES 
     Hereinafter, the present invention will be explained in more detail referring to embodiments. However, embodiments according to the present invention may be modified into various other types, and the scope of the present invention should not be limited to the embodiments described below. The embodiments of the present invention are provided for completely explaining the present invention to a person having an average knowledge in the art. 
     Experiment #1 
     Preparation Example 1 
     To a 500 ml, round-bottom flask, 100 ml of tetrahydrofuran and 1 g of n-butyllithium (10 wt % in n-hexane) were added, N,N,N′,N′,1-pentamethyl-1-vinylsilanediamine (molar ratio of 3 mol in contrast to 1 mol of [act. Li]) was added, followed by reacting at 10° C. for 30 minutes to prepare a solution containing a functional chain (15.6 mmol/l). Through GC analysis, N,N,N′,N′,1-pentamethyl-1-vinylsilanediamine was not detected after the reaction, and the achievement of the reaction was secured. 
     Example 1-1 
     To a 20 L, autoclave reactor, 3 kg of n-hexane, 215 g of styrene, 745 g of 1,3-butadiene and 1.29 g of 2,2-bis(2-oxoranyl)propane as a polar additive were injected, then, 3.2 g of n-butyllithium (10 wt % in n-hexane) was injected, the internal temperature of the reactor was adjusted to 60° C., and an adiabatic reaction with heating was performed. After about minutes lapse, 39 g of 1,3-butadiene was injected for capping the terminals of a polymer with butadiene. After about 10 minutes, N,N-diethyl-3-(trimethoxysilyl)propan-1-amine was injected as a modifier and reacted for 15 minutes (molar ratio of [DTP]:[act. Li]=1.5:1, molar ratio of [modifier]: [act. Li]=0.7:1). Then, the solution containing a functional chain in Preparation Example 1 was added and reacted for 15 minutes (molar ratio of [act. Li]:[macromonomer]=1:1), and the reaction was quenched using ethanol. 33 g of a solution in which 30 wt % of Wingstay K antioxidant was dissolved in hexane was added thereto. The polymer thus obtained was injected into hot water heated using steam and stirred to remove solvents and roll dried to remove remaining solvents and water to prepare a modified styrene-butadiene copolymer. 
     Example 1-2 
     A modified styrene-butadiene copolymer was prepared by performing the same method in Example 1-1 except for using 
     N,N-bis(3-(triethoxysilyl)propyl)-3,6,9,12,15-pentaoxanonadecan-1-amine instead of N,N-diethyl-3-(trimethoxysilyl)propan-1-amine as a modifier(molar ratio of [modifier]: [act. Li]=0.7:1). 
     Example 1-3 
     A modified styrene-butadiene copolymer was prepared by performing the same method in Example 1-1 except for using 3,3′-(1,1,3,3-tetramethoxydisiloxane-1,3-diyl)bis(N,N-diethylpropan-1-amine instead of N,N-diethyl-3-(trimethoxysilyl)propan-1-amine as a modifier(molar ratio of [modifier]: [act. Li]=0.7:1). 
     Comparative Example 1-1 
     A modified styrene-butadiene copolymer was prepared by performing the same method in Example 1-1 except for injecting the solution containing a functional chain prepared in Preparation Example 1 instead of the n-butyllithium in Example 1-1 such that the mol of the macromonomer was the same as the n-butyllithium in Example 1-1, performing the adiabatic reaction with heating, not performing a step of adding a modifier and a functional chain and reacting, and quenching the reaction after butadiene capping. 
     Comparative Example 1-2 
     To a 20 L, autoclave reactor, 3 kg of n-hexane, 215 g of styrene, 745 g of 1,3-butadiene and 1.29 g of 2,2-bis(2-oxoranyl)propane as a polar additive were injected, then, 3.2 g of n-butyllithium (10 wt % in n-hexane) was injected, the internal temperature of the reactor was adjusted to 60° C., and an adiabatic reaction with heating was performed. After about minutes lapse, 39 g of 1,3-butadiene was injected for capping the terminals of a polymer with butadiene. After about 10 minutes, N,N-diethyl-3-(trimethoxysilyl)propan-1-amine was injected as a modifier and reacted for 15 minutes (molar ratio of [DTP]:[act. Li]=1.5:1, molar ratio of [modifier]: [act. Li]=0.7:1). Then, the reaction was quenched using ethanol. 33 g of a solution in which 30 wt % of Wingstay K antioxidant was dissolved in hexane was added thereto. The polymer thus obtained was injected into hot water heated using steam and stirred to remove solvents and roll dried to remove remaining solvents and water to prepare a modified styrene-butadiene copolymer. 
     Comparative Example 1-3 
     A modified styrene-butadiene copolymer was prepared by performing the same method in Comparative Example 1-2 except for injecting 3,3′-(1,1,3,3-tetramethoxydisiloxane-1,3-diyl)bis(N,N-diethylpropan-1-amine) instead of N,N-diethyl-3-(trimethoxysilyl)propan-1-amine as a modifier (molar ratio of [modifier]: [act. Li]=0.7:1). 
     Comparative Example 1-4 
     A modified styrene-butadiene copolymer was prepared by performing the same method in Comparative Example 1-2 except for using N,N-bis(3-(triethoxysilyl)propyl)-3,6,9,12,15-pentaoxanonadecan-1-amine instead of N,N-diethyl-3-(trimethoxysilyl)propan-1-amine as a modifier (molar ratio of [modifier]: [act. Li]=0.7:1). 
     Comparative Example 1-5 
     A modified styrene-butadiene copolymer was prepared by performing the same method in Comparative Example 1-2 except for injecting the solution containing a macromonomer prepared in Preparation Example 1 instead of the n-butyllithium in Comparative Example 1-2 such that the mol of the functional chain was the same as the n-butyllithium in Comparative Example 1-2, and performing the adiabatic reaction with heating in Comparative Example 1-2. 
     Evaluation of Properties of Polymer 
     With respect to each of the modified or unmodified conjugated diene-based polymers prepared in the Examples and Comparative Examples, the styrene unit and vinyl contents in each polymer, a weight average molecular weight (Mw, x10 3  g/mol), a number average molecular weight (Mn, x10 3  g/mol), molecular weight distribution (PDI, MWD), mooney viscosity (MV), the rate of change of mooney viscosity, and the Si and N contents were measured, respectively. The results are shown in Table 1 below. 
     1) Styrene unit and vinyl contents (wt %) 
     The styrene unit (SM) and vinyl contents in each polymer were measured and analyzed using Varian VNMRS 500 MHz NMR. 
     When measuring NMR, 1,1,2,2-tetrachloroethane was used as a solvent, and styrene unit and vinyl contents were calculated by calculating a solvent peak as 5.97 ppm, and regarding 7.2-6.9 ppm as random styrene peaks, 6.9-6.2 ppm as block styrene peaks, 5.8-5.1 ppm as 1,4-vinyl peaks, and 5.1-4.5 ppm as 1,2-vinyl peaks. 
     2) Weight average molecular weight (Mw, x10 3  g/mol), number average molecular weight (Mn, x10 3  g/mol), and molecular weight distribution (PDI, MWD) 
     By gel permeation chromatography (GPC) analysis, a weight average molecular weight (Mw) and a number average molecular weight (Mn) were measured and a molecular weight distribution curve was obtained. In addition, molecular weight distribution (PDI, MWD, Mw/Mn) was calculated from each molecular weight thus measured. Particularly, GPC was conducted using two columns of PLgel Olexis (Polymer Laboratories Co.) and one column of PLgel mixed-C (Polymer Laboratories Co.) in combination, and polystyrene (PS) as a GPC standard material for calculating the molecular weights. 
     A solvent for measuring GPC was prepared by mixing tetrahydrofuran with 2 wt % of an amine compound. 
     3) Mooney viscosity and rate of change of mooney viscosity 
     The mooney viscosity (MV, (ML1+4, @100° C.) MU) was measured by using MV-2000 (ALPHA Technologies Co.) using Large Rotor at a rotor speed of 2±0.02 rpm at 100° C. In this case, a specimen used was stood at room temperature (23±3° C.) for 30 minutes or more, and 27±3 g of the specimen was collected and put in a die cavity, and then, Platen was operated for 4 minutes for measurement. 
     In addition, the rate of change of mooney viscosity was obtained by standing each same specimen at room temperature for 30 days, measuring the mooney viscosity by the above-described method, and calculating by Mathematical Formula 1 below. 
       MV R =[(MV f −MV i )/MV i ]×100   [Mathematical Formula 1]
 
     In Mathematical Formula 1, MV R  is the rate of change of mooney viscosity, MV f  is mooney viscosity at 100° C. after standing the polymer at 25° C. for 30 days, and MV i  is initial mooney viscosity of the polymer at 100° C. 
     4) Si Content 
     The Si content was measured by an ICP analysis method, which used an inductively coupled plasma optical emission spectroscopy (ICP-OES; Optima 7300DV). Particularly, measurement was performed by adding about 0.7 g of a specimen to a platinum (Pt) crucible and adding about 1 mL of concentrated sulfuric acid (98 wt %, electronic grade) thereto, heating at 300° C. for 3 hours, incinerating the specimen in an electrical furnace (Thermo Scientific, Lindberg Blue M) by the following program of steps 1 to 3: 
     1) step 1: initial temp 0° C., rate (temp/hr) 180° C./hr, temp (holdtime) 180° C. (lhr) 
     2) step 2: initial temp 180° C., rate (temp/hr) 85° C./hr, temp (holdtime) 370° C. (2 hr) 
     3) step 3: initial temp 370° C., rate (temp/hr) 47° C./hr, temp (holdtime) 510° C. (3 hr), 
     adding 1 mL of concentrated nitric acid (48 wt %) and 20 pl of concentrated hydrofluoric acid (50 wt %) to a residue, sealing the platinum crucible and shaking for 30 minutes or more, adding 1 mL of boric acid to the specimen, storing at 0° C. for 2 hours or more, diluting in 30 mL of ultrapure water, and performing incineration. 
     5) N content 
     The N content was measured through an NSX analysis method using a quantitative analyzer of a trace amount of nitrogen (NSX-2100H). Particularly, the quantitative analyzer of a trace amount of nitrogen (Auto sampler, Horizontal furnace, PMT &amp; Nitrogen detector) was turned on, carrier gas flow amounts were set to 250 ml/min for Ar, 350 ml/min for O 2 , and 300 ml/min for ozonizer, a heater was set to 800° C., and the analyzer was stood for about 3 hours for stabilization. After stabilizing the analyzer, a calibration curve of calibration curve ranges of 5 ppm, 10 ppm, 50 ppm, 100 ppm and 500 ppm was made using Nitrogen standard (AccuStandard S-22750-01-5 ml), and an area corresponding to each concentration was obtained. Then, by using the ratios of concentrations to areas, a straight line was made. After that, a ceramic boat holding 20 mg of a specimen was put in the auto sampler of the analyzer and measurement was conducted to obtain an area. By using the area of the specimen thus obtained and the calibration curve, the N content was calculated. 
     
       
         
           
               
               
               
             
               
                   
                 TABLE 1 
               
             
            
               
                   
                   
               
               
                   
                 Example 
                 Comparative Example 
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 Division 
                 1-1 
                 1-2 
                 1-3 
                 1-1 
                 1-2 
                 1-3 
                 1-4 
                 1-5 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
               
            
               
                 NMR (wt %) 
                 SM 
                 20.9 
                 21.0 
                 21.0 
                 20.6 
                 21.0 
                 21.3 
                 20.9 
                 21.0 
               
               
                   
                 Vinyl 
                 50.2 
                 49.7 
                 50.1 
                 50.5 
                 50.2 
                 50.1 
                 50.47 
                 50.0 
               
               
                 GPC 
                 Mn (×10 3   
                 396 
                 410 
                 385 
                 365 
                 405 
                 380 
                 402 
                 353 
               
               
                   
                 g/mol) 
               
               
                   
                 Mw (×10 3   
                 523 
                 660 
                 551 
                 402 
                 514 
                 467 
                 651 
                 469 
               
               
                   
                 g/mol) 
               
               
                   
                 PDI 
                 1.32 
                 1.61 
                 1.43 
                 1.10 
                 1.27 
                 1.23 
                 1.62 
                 1.33 
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 Mooney viscosity (MV) 
                 63 
                 80 
                 73 
                 41 
                 62 
                 53 
                 96 
                 58 
               
               
                 Mooney viscosity after 
                 68 
                 85 
                 77 
                 50 
                 76 
                 66 
                 118 
                 72 
               
               
                 standing for 30 days 
               
               
                 Rate of change of 
                 8 
                 6 
                 6 
                 21 
                 22 
                 25 
                 23 
                 24 
               
               
                 mooney viscosity (%) 
               
               
                 Si content (ppm) 
                 430 
                 500 
                 492 
                 231 
                 78 
                 155 
                 162 
                 413 
               
               
                 N content (ppm) 
                 382 
                 377 
                 419 
                 230 
                 39 
                 77 
                 42 
                 372 
               
            
           
           
               
               
               
               
               
               
               
               
               
               
            
               
                 N- 
                 Unit 
                 3 
                 3 
                 3 
                 3 
                 — 
                 — 
                 — 
                 3 
               
               
                 functional 
                 number 
               
               
                 group- 
                 Position 
                 Modifier 
                 Modifier 
                 Modifier 
                 Initial 
                 — 
                 — 
                 — 
                 Initial 
               
               
                 containing 
                   
                 side 
                 side 
                 side 
                 terminal 
                   
                   
                   
                 terminal 
               
               
                 monomer 
                   
                 terminal 
                 terminal 
                 terminal 
               
               
                   
               
            
           
         
       
     
     As shown in Table 1 above, in Examples 1-1 and 1-2, Si and N atoms were present in a polymer molecule, and the N content was largely increased in contrast to Comparative Examples 1-2 to 1-4. It could be found that the markedly small N content was measured due to the non-existence of a functional chain. 
     Evaluation of Properties of Rubber Molded Article 
     In order to compare and analyze the physical properties of rubber compositions including the modified styrene-butadiene copolymers prepared in the Examples and Comparative Examples, and molded articles manufactured therefrom, tensile properties and viscoelasticity properties were measured, respectively, and the results are shown in Table 3 below. 
     1) Preparation of Rubber Specimen 
     Blending was performed using each of the modified or unmodified conjugated diene-based polymers of the Examplesand Comparative Examples as a raw material rubber under the compounding conditions shown in Table 2 below. The raw materials in Table 2 are represented by parts by weight based on 100 parts by weight of the raw material rubber. 
     
       
         
           
               
               
               
               
             
               
                   
                 TABLE 2 
               
               
                   
                   
               
               
                   
                   
                   
                 Amount  
               
               
                   
                 Division 
                 Raw material 
                 (parts by weight) 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
            
               
                   
                 First stage mulling 
                 Rubber 
                 100 
               
               
                   
                   
                 Silica 
                 70 
               
               
                   
                   
                 Coupling agent 
                 11.2 
               
               
                   
                   
                 (X50S) 
                   
               
               
                   
                   
                 Process oil 
                 37.5 
               
               
                   
                   
                 Zinc white 
                 3 
               
               
                   
                   
                 Stearic acid 
                 2 
               
               
                   
                   
                 Antioxidant 
                 2 
               
               
                   
                   
                 Antiaging agent 
                 2 
               
               
                   
                   
                 wax 
                 1 
               
               
                   
                 Second stage mulling 
                 Sulfur 
                 1.5 
               
               
                   
                   
                 Rubber accelerator 
                 1.75 
               
               
                   
                   
                 Vulcanization 
                 2 
               
               
                   
                   
                 accelerator 
                   
               
               
                   
                   
               
            
           
         
       
     
     Particularly, the rubber specimen was mulled via a first stage mulling and a second stage mulling. In the first stage mulling, a raw material rubber, silica (filler), an organic silane coupling agent (X50S, Evonik), a process oil (TADE oil), zinc oxide (ZnO), stearic acid, an antioxidant (TMQ (RD)) (2,2,4-trimethyl-1,2-dihydroquinoline polymer), an antiaging agent (6PPD ((dimethylbutyl)-N-phenyl-phenylenediamine) and wax (Microcrystaline Wax) were mulled using a banbury mixer equipped with a temperature controlling apparatus. In this case, the initial temperature of a mulling apparatus was controlled to 70° C., and after finishing mixing, a first compound mixture was obtained at a discharge temperature of 145° C. to 155° C. In the second stage mulling, the first compound mixture was cooled to room temperature, and the first compound mixture, sulfur, a rubber accelerator (diphenylguanidine (DPG)), and a vulcanization accelerator (N-cyclohexyl-2-benzothiazylsulfenamide (CZ)) were added to the mulling apparatus and mixed at a temperature of 100° C. or less to obtain a second compound mixture. Then, via a curing process at 160° C. for 20 minutes, a rubber specimen was formed. 
     2) Tensile Properties 
     For measuring the tensile properties, each test specimen was manufactured and tensile stress when stretched by 300% (300% modulus) of each specimen was measured according to an ASTM 412 tensile test method. Particularly, tensile properties were measured using a Universal Test Machin 4204 tensile tester (Instron Co.) in a rate of 50 cm/min at room temperature. 
     3) Viscoelasticity Properties 
     The viscoelasticity properties were secured by measuring viscoelasticity behavior on thermodynamic deformation at each measurement temperature (−60° C-60° C.) with a frequency of 10 Hz by using a dynamic mechanical analyzer (GABO Co.) in a film tension mode and securing a tan δ value. From the resultant values, if a tan 5 value at a low temperature of 0° C. increases, wet skid resistance becomes better, and if a tan S at a high temperature of 60° C. decreases, hysteresis loss decreases, and low running resistance (fuel consumption ratio) becomes better. The resultant values in Table 3 were indexed (%) by setting the resultant values of Comparative Example 1-1 to 100, and thus, the higher numerical value means better results. 
     4) Processability Properties 
     By measuring the mooney viscosity (MV, (ML1+4, @100° C.) MU) of the second compound mixture obtained during 1) preparation of rubber specimen, the processability properties of each polymer was compared and analyzed, and in this case, the lower the measured value of the moony viscosity is, the better the processability properties are. The resultant values in Table 3 were indexed (%) by setting the resultant values of Comparative Example 1-1 to 100, and thus, the higher numerical value means better results. 
     Particularly, by using MV-2000 (ALPHA Technologies Co.) using Large Rotor at a rotor speed of 2±0.02 rpm at 100° C., each secondary compound mixture was stood at room temperature (23±3° C.) for 30 minutes or more, and 27±3 g was collected and put in a die cavity, and then, Platen was operated for 4 minutes for measurement. 
     
       
         
           
               
               
               
             
               
                   
                 TABLE 3 
               
             
            
               
                   
                   
               
               
                   
                 Example 
                 Comparative Example 
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 Division 
                 1-1 
                 1-2 
                 1-3 
                 1-1 
                 1-2 
                 1-3 
                 1-4 
                 1-5 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 300% modulus (kgf/cm 2 ) 
                 162 
                 164 
                 160 
                 148 
                 149 
                 147 
                 152 
                 161 
               
            
           
           
               
               
               
               
               
               
               
               
               
               
            
               
                 Viscoelasticity 
                 Tan δ (at 
                 100 
                 103 
                 100 
                 100 
                 96 
                 99 
                 97 
                 98 
               
               
                 properties 
                 0° C., Index) 
               
               
                   
                 Tan δ (at 
                 118 
                 124 
                 122 
                 100 
                 97 
                 98 
                 102 
                 118 
               
               
                   
                 60° C., Index) 
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 Processability 
                 103 
                 104 
                 104 
                 94 
                 100 
                 98 
                 102 
                 74 
               
               
                 properties (Index) 
               
               
                   
               
               
                 * For the indexes, the viscoelasticity properties are values based on Comparative Example 1-1, and the processability properties are values based on Comparative Example 1-2. 
               
            
           
         
       
     
     As shown in Table 3, it was confirmed that Examples 1- and 1-2, which used the modified conjugated diene-based polymers according to embodiments of the present invention, showed excellent processability properties and at the same time, excellent tensile properties and viscoelasticity properties when compared with Comparative Examples 1-1 to 1-5. 
     It could be confirmed that Examples 1-1 and 1-2 showed very marked difference in rotation resistance and improved results of tensile properties when compared with Comparative Examples 1-1 to 1-4, and showed equal or better tensile properties, improved viscoelasticity properties and markedly improved processability properties when compared with Comparative Example 1-5. It could be found that these effects were achieved in the Examples due to the use of the functional chain together with a modification initiator and not using a modifier coupled with a functional group, and markedly significantly different processability was shown. 
     Through this, it was confirmed that marked effects not shown in Comparative Example 1-3 were shown in the modified conjugated diene-based polymer of the present invention by being prepared by a preparation method including a step of reacting a functional chain after modification reaction. Through the effect difference, it could be anticipated that the modified conjugated diene-based polymer of the present invention is a copolymer having a different structure from Comparative Example 1-5, for example, a structure similar to a graft copolymer through the coupling of the functional chain including the repeating unit derived from the N-functional group-containing monomer derived from the functional chain with the non-functional chain of the modified polymer via the functional group derived from a modifier. 
     Experiment #2 
     Preparation Example 2 
     To a 500 ml, round-bottom flask, 100 ml of tetrahydrofuran and 1 g of n-butyllithium (10 wt % in n-hexane) were added, N,N′-diethyl-N,N′-diisopropyl-1,1-divinylsilanediamine (molar ratio of 3 mol in contrast to 1 mol of [act. Li]) was added, followed by reacting at 10° C. for 30 minutes to prepare a solution containing a functional chain (15.6 mmol/l). Through GC analysis, N,N′-diethyl-N,N′-diisopropyl-1,1-divinylsilanediamine was not detected after the reaction, and the achievement of the reaction was secured. 
     Example 2-1 
     To a 20 L, autoclave reactor, 3 kg of n-hexane, 215 g of styrene, 745 g of 1,3-butadiene and 1.29 g of 2,2-bis(2-oxoranyl)propane as a polar additive were injected, then, 3.2 g of n-butyllithium (10 wt % in n-hexane) was injected, the internal temperature of the reactor was adjusted to 60° C., and an adiabatic reaction with heating was performed. After about minutes lapse, 39 g of 1,3-butadiene was injected for capping the terminals of a polymer with butadiene. After about minutes, N-(3-(1H-imidazol-1-yl)propyl)-3-(triethoxysilyl)-N-(3-(triethoxysilyl)propyl)propan-1-amine was injected as a modifier and reacted for 15 minutes (molar ratio of [DTP]:[act. Li]=1.5:1, molar ratio of [modifier]: [act. Li]=0.7:1). Then, the solution containing a functional chain prepared in Preparation Example 2 was added and reacted for 15 minutes (molar ratio of [functional chain]:[act. Li]=1:1), and the reaction was quenched using ethanol. 33 g of a solution in which 30 wt % of Wingstay K antioxidant was dissolved in hexane was added thereto. The polymer thus obtained was injected into hot water heated using steam and stirred to remove solvents and roll dried to remove remaining solvents and water to prepare a modified styrene-butadiene copolymer. 
     Example 2-2 
     A modified styrene-butadiene copolymer was prepared by performing the same method in Example 2-1 except for using 3,3′-(1,1,3,3-tetramethoxydisiloxane-1,3-diyl)bis(N,N-diethylpropan-1-amine) instead of N-(3-(1H-imidazol-1-yl)propyl)-3-(triethoxysilyl)-N-(3-(triethoxysilyl)propyl)propan-1-amine as a modifier (molar ratio of [modifier]: [act. Li]=0.7:1). 
     Comparative Example 2-1 
     A modified styrene-butadiene copolymer was prepared by performing the same method in Example 2-1 except for injecting the solution containing a functional chain prepared in Preparation Example 2 instead of the n-butyllithium in Example 2-1 such that the mol of the functional chain was the same as the n-butyllithium in Example 2-1, performing the adiabatic reaction with heating, not performing a step of adding a modifier and a functional chain and reacting, and quenching the reaction after butadiene capping. 
     Comparative Example 2-2 
     To a 20 L, autoclave reactor, 3 kg of n-hexane, 215 g of styrene, 745 g of 1,3-butadiene and 1.29 g of 2,2-bis(2-oxoranyl)propane as a polar additive were injected, then, 3.2 g of n-butyllithium (10 wt % in n-hexane) was injected, the internal temperature of the reactor was adjusted to 60° C., and an adiabatic reaction with heating was performed. After about minutes lapse, 39 g of 1,3-butadiene was injected for capping the terminals of a polymer with butadiene. After about 10 minutes, N,N-diethyl-3-(trimethoxysilyl)propan-1-amine was injected as a modifier and reacted for 15 minutes (molar ratio of [DTP]:[act. Li]=1.5:1, molar ratio of [modifier]: [act. Li]=0.7:1). Then, the reaction was quenched using ethanol. 33 g of a solution in which 30 wt % of Wingstay K antioxidant was dissolved in hexane was added thereto. The polymer thus obtained was injected into hot water heated using steam and stirred to remove solvents and roll dried to remove remaining solvents and water to prepare a modified styrene-butadiene copolymer. 
     Comparative Example 2-3 
     A modified styrene-butadiene copolymer was prepared by performing the same method in Comparative Example 2-2 except for using 3,3′-(1,1,3,3-tetramethoxydisiloxane-1,3-diyl)bis(N,N-diethylpropan-1-amine) instead of N,N-diethyl-3-(trimethoxysilyl)propan-1-amine as a modifier (molar ratio of [modifier]: [act. Li]=0.7:1). 
     Comparative Example 2-4 
     A modified styrene-butadiene copolymer was prepared by performing the same method in Comparative Example 2-2 except for injecting the solution containing a functional chain prepared in Preparation Example 2 instead of the n-butyllithium in Comparative Example 2-2 such that the mol of the functional chain was the same as the n-butyllithium in Comparative Example 2-2, and performing the adiabatic reaction with heating. 
     Comparative Example 2-5 
     A modified styrene-butadiene copolymer was prepared by performing the same method in Comparative Example 2-4 except for injecting 3,3′-(1,1,3,3-tetramethoxydisiloxane-1,3-diyl)bis(N,N-diethylpropan-1-amine) instead of N,N-diethyl-3-(trimethoxysilyl)propan-1-amine as a modifier (molar ratio of [modifier]: [act. Li]=0.7:1). 
     Evaluation of Properties of Polymer 
     With respect to each of the modified or unmodified conjugated diene-based polymers prepared in the Examples and Comparative Examples, the styrene unit and vinyl contents in each polymer, a weight average molecular weight (Mw, x10 3  g/mol), a number average molecular weight (Mn, x10 3  g/mol), molecular weight distribution (PDI, MWD), mooney viscosity (MV), the rate of change of mooney viscosity, and the Si and N contents were measured, respectively, by the same methods in Experiment #1. The results are shown in Table 4 below. 
     
       
         
           
               
               
               
             
               
                   
                 TABLE 4 
               
             
            
               
                   
                   
               
               
                   
                 Example 
                 Comparative Example 
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                 Division 
                 2-1 
                 2-2 
                 2-1 
                 2-2 
                 2-3 
                 2-4 
                 2-5 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 NMR (wt %) 
                 SM 
                 20.5 
                 21.0 
                 20.3 
                 21.4 
                 20.7 
                 20.6 
                 21.2 
               
               
                   
                 Vinyl 
                 49.5 
                 50.2 
                 50.2 
                 50.8 
                 50.1 
                 49.5 
                 49.0 
               
               
                 GPC 
                 Mn (×10 3   
                 420 
                 365 
                 394 
                 405 
                 380 
                 402 
                 380 
               
               
                   
                 g/mol) 
               
               
                   
                 Mw (×10 3   
                 672 
                 481 
                 453 
                 514 
                 467 
                 522 
                 505 
               
               
                   
                 g/mol) 
               
               
                   
                 PDI 
                 1.60 
                 1.32 
                 1.15 
                 1.27 
                 1.23 
                 1.30 
                 1.33 
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                 Mooney viscosity (MV) 
                 91 
                 56 
                 51 
                 62 
                 53 
                 63 
                 60 
               
               
                 Mooney viscosity after 
                 97 
                 59 
                 66 
                 76 
                 68 
                 78 
                 73 
               
               
                 standing for 30 days 
               
               
                 Rate of change of 
                 7 
                 5 
                 30 
                 23 
                 28 
                 24 
                 22 
               
               
                 mooney viscosity (%) 
               
               
                 Si content (ppm) 
                 501 
                 509 
                 225 
                 78 
                 155 
                 414 
                 489 
               
               
                 N content (ppm) 
                 459 
                 426 
                 224 
                 39 
                 77 
                 374 
                 409 
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 N- 
                 Unit 
                 3 
                 3 
                 3 
                 — 
                 — 
                 3 
                 3 
               
               
                 functional 
                 number 
               
               
                 group- 
                 Position 
                 Modifier 
                 Modifier 
                 Initial 
                 — 
                 — 
                 Initial 
                 Initial 
               
               
                 containing 
                   
                 side 
                 side 
                 terminal 
                   
                   
                 terminal 
                 terminal 
               
               
                 monomer 
                   
                 terminal 
                 terminal 
               
               
                   
               
            
           
         
       
     
     As shown in Table 4 above, in Examples 2-1 and 2-2, Si and N atoms were present in a polymer molecule, and the N content was largely increased in contrast to Comparative Examples 2-1 to 2-3. 
     Evaluation of Properties of Rubber Molded Article 
     In order to compare and analyze the physical properties of rubber compositions including the modified styrene-butadiene copolymers prepared in the Examples and Comparative Examples, and molded articles manufactured therefrom, tensile properties and viscoelasticity properties were measured, respectively, as in Experiment #1, and the results are shown in Table 5 below. The specimen of the molded article was also manufactured by the same method in Experiment #1. 
     
       
         
           
               
               
               
             
               
                   
                 TABLE 5 
               
             
            
               
                   
                   
               
               
                   
                 Example 
                 Comparative Example 
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                 Division 
                 2-1 
                 2-2 
                 2-1 
                 2-2 
                 2-3 
                 2-4 
                 2-5 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                 300% modulus (kgf/cm 2 ) 
                 163 
                 160 
                 148 
                 149 
                 147 
                 161 
                 163 
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 Viscoelasticity 
                 Tan δ (at 
                 101 
                 100 
                 100 
                 97 
                 100 
                 99 
                 101 
               
               
                 properties 
                 0° C., Index) 
               
               
                   
                 Tan δ (at 
                 118 
                 117 
                 100 
                 98 
                 99 
                 114 
                 115 
               
               
                   
                 60° C., Index) 
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                 Processability 
                 100 
                 101 
                 95 
                 100 
                 98 
                 75 
                 74 
               
               
                 properties (Index) 
               
               
                   
               
               
                 * For the indexes, the viscoelasticity properties are values based on Comparative Example 2-1, and the processability properties are values based on Comparative Example 2-2. 
               
            
           
         
       
     
     As shown in Table 5, it was confirmed that Examples 2- and 2-2, which used the modified conjugated diene-based polymers according to embodiments of the present invention, showed excellent processability properties and at the same time, excellent tensile properties and viscoelasticity properties when compared with Comparative Examples 2-1 to 2-5. 
     It could be confirmed that Examples 2-1 and 2-2 showed very marked difference in rotation resistance and improved results of tensile properties when compared with Comparative Examples 2-1 to 2-3, and showed equal or better tensile properties, improved viscoelasticity properties and markedly improved processability properties when compared with Comparative Examples 2-4 and 2-5. It could be found that these effects were achieved in the Examples due to the use of the functional chain together with a modification initiator and not using a modifier coupled with a functional group, and markedly significantly different processability was shown. 
     Through this, it was confirmed that marked effects not shown in Comparative Examples 2-4 and 2-5 were shown in the modified conjugated diene-based polymer of the present invention by being prepared by a preparation method including a step of reacting with a functional chain after modification reaction. Through the effect difference, it could be anticipated that the modified conjugated diene-based polymer of the present invention is a copolymer having a different structure from the Comparative Examples, for example, a structure similar to a graft copolymer through the coupling of the functional chain including the repeating unit derived from the N-functional group-containing monomer derived from the functional chain with the non-functional chain of the modified polymer via the functional group derived from a modifier. 
     Experiment #3 
     Preparation Example 3 
     To a 500 ml, round-bottom flask, 100 ml of tetrahydrofuran and 1 g of n-butyllithium (10 wt % in n-hexane) were added, N,N-dimethyl-4-methylenehexene-5-en-1-amine (molar ratio of 3 mol in contrast to 1 mol of [act. Li]) was added, followed by reacting at 10° C. for 30 minutes to prepare a solution containing a functional chain (15.6 mmol/l). Through GC analysis, N,N-dimethyl-4-methylenehexene-5-en-1-amine was not detected after the reaction, and the achievement of the reaction was secured. 
     Example 3-1 
     To a 20 L, autoclave reactor, 3 kg of n-hexane, 215 g of styrene, 745 g of 1,3-butadiene and 1.29 g of 2,2-bis(2-oxoranyl)propane as a polar additive were injected, then, 3.2 g of n-butyllithium (10 wt % in n-hexane) was injected, the internal temperature of the reactor was adjusted to 60° C., and an adiabatic reaction with heating was performed. After about minutes lapse, 39 g of 1,3-butadiene was injected for capping the terminals of a polymer with butadiene. After about minutes, 1,1,1-trimethyl-N-(3-(triethoxysilyl)propyl)-N-(trimethylsilyl)silaneamine was injected as a modifier and reacted for 15 minutes (molar ratio of [DTP]:[act. Li]=1.5:1, molar ratio of [modifier]: [act. Li]=0.7:1). Then, the solution containing a functional chain prepared in Preparation Example 3 was added and reacted for 15 minutes (molar ratio of [act. Li]: [functional chain]=1:2), and the reaction was quenched using ethanol. 33 g of a solution in which 30 wt % of Wingstay K antioxidant was dissolved in hexane was added thereto. The polymer thus obtained was injected into hot water heated using steam and stirred to remove solvents and roll dried to remove remaining solvents and water to prepare a modified styrene-butadiene copolymer. 
     Example 3-2 
     A modified styrene-butadiene copolymer was prepared by performing the same method in Example 3-1 except for using 3-(2,2-dimethoxy-1,2-azasilolidin-1-yl)-N,N-bis(3-(trimethoxysilyl)propyl)propan-1-amine instead of 1,1,1-trimethyl-N-(3-(triethoxysilyl)propyl)-N-(trimethylsilyl)silaneamine as a modifier in Example 3-1 (molar ratio of [modifier]: [act. Li]=0.7:1). 
     Comparative Example 3-1 
     A modified styrene-butadiene copolymer was prepared by performing the same method in Example 3-1 except for injecting the solution containing a functional chain prepared in 
     Preparation Example 3 instead of the n-butyllithium in Example 3-1 such that the mol of the functional chain was the same as the n-butyllithium in Example 3-1, performing the adiabatic reaction with heating, not performing a step of adding a modifier and a functional chain and reacting, and quenching the reaction after butadiene capping. 
     Comparative Example 3-2 
     To a 20 L, autoclave reactor, 3 kg of n-hexane, 215 g of styrene, 745 g of 1,3-butadiene and 1.29 g of 2,2-bis(2-oxoranyl)propane as a polar additive were injected, then, 3.2 g of n-butyllithium (10 wt % in n-hexane) was injected, the internal temperature of the reactor was adjusted to 60° C., and an adiabatic reaction with heating was performed. After about 30 minutes lapse, 39 g of 1,3-butadiene was injected for capping the terminals of a polymer with butadiene. After about minutes, 3,3′-(piperazine-1,4-diyl)bis(N,N-bis(3-(triethoxysilyl)propyl)propan-1-amine was injected as a modifier and reacted for 15 minutes (molar ratio of [DTP]:[act. Li]=1.5:1, molar ratio of [modifier]: [act. Li]=0.7:1). 
     Then, the reaction was quenched using ethanol. 33 g of a solution in which 30 wt % of Wingstay K antioxidant was dissolved in hexane was added thereto. The polymer thus obtained was injected into hot water heated using steam and stirred to remove solvents and roll dried to remove remaining solvents and water to prepare a modified styrene-butadiene copolymer. 
     Comparative Example 3-3 
     A modified styrene-butadiene copolymer was prepared by performing the same method in Comparative Example 3-2 except for injecting the solution containing a functional chain prepared in Preparation Example 3 instead of the n-butyllithium in Comparative Example 3-2 such that the mol of the functional chain was the same as the n-butyllithium in Comparative Example 3-2, and performing the adiabatic reaction with heating. 
     Evaluation of Properties of Polymer 
     With respect to each of the modified or unmodified conjugated diene-based polymers prepared in the Examples and Comparative Examples, the styrene unit and vinyl contents in each polymer, a weight average molecular weight (Mw, x10 3  g/mol), a number average molecular weight (Mn, x10 3  g/mol), molecular weight distribution (PDI, MWD), mooney viscosity (MV), the rate of change of mooney viscosity, and the Si and N contents were measured, respectively, by the same methods in Experiment #1. The results are shown in Table 6 below. 
     
       
         
           
               
               
               
             
               
                   
                 TABLE 6 
               
             
            
               
                   
                   
               
               
                   
                 Example 
                 Comparative Example 
               
            
           
           
               
               
               
               
               
               
            
               
                 Division 
                 3-1 
                 3-2 
                 3-1 
                 3-2 
                 3-3 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                 NMR (wt %) 
                 SM 
                 21.1 
                 21.5 
                 20.7 
                 21.4 
                 20.7 
               
               
                   
                 Vinyl 
                 49.6 
                 49.5 
                 49.6 
                 50.2 
                 50.0 
               
               
                 GPC 
                 Mn (×10 3   
                 375 
                 525 
                 389 
                 459 
                 459 
               
               
                   
                 g/mol) 
               
               
                   
                 Mw (×10 3   
                 525 
                 903 
                 459 
                 798 
                 818 
               
               
                   
                 g/mol) 
               
               
                   
                 PDI 
                 1.40 
                 1.72 
                 1.18 
                 1.73 
                 1.78 
               
            
           
           
               
               
               
               
               
               
            
               
                 Mooney viscosity (MV) 
                 64 
                 135 
                 51 
                 114 
                 119 
               
               
                 Mooney viscosity after 
                 67 
                 142 
                 65 
                 143 
                 146 
               
               
                 standing for 30 days 
               
               
                 Rate of change of 
                 4 
                 5 
                 28 
                 25 
                 23 
               
               
                 mooney viscosity (%) 
               
               
                 Si content (ppm) 
                 236 
                 236 
                 — 
                 312 
                 319 
               
               
                 N content (ppm) 
                 207 
                 246 
                 112 
                 156 
                 272 
               
            
           
           
               
               
               
               
               
               
               
            
               
                 N- 
                 Unit 
                 3 
                 3 
                 3 
                 — 
                 3 
               
               
                 functional 
                 number 
               
               
                 group- 
                 Position 
                 Modifier 
                 Modifier 
                 Initial 
                 — 
                 Initial 
               
               
                 containing 
                   
                 side 
                 side 
                 terminal 
                   
                 terminal 
               
               
                 monomer 
                   
                 terminal 
                 terminal 
               
               
                   
               
            
           
         
       
     
     As shown in Table 6 above, in Examples 3-1 and 3-2, Si and N atoms were present in a polymer molecule, and the N content was largely increased in contrast to Comparative Examples 3-1 and 3-2. 
     Evaluation of Properties of Rubber Molded Article 
     In order to compare and analyze the physical properties of rubber compositions including the modified styrene-butadiene copolymers prepared in the Examples and Comparative Examples, and molded articles manufactured therefrom, tensile properties and viscoelasticity properties were measured, respectively, as in Experiment #1, and the results are shown in Table 7 below. The specimen of the molded article was also manufactured by the same method in Experiment #1. 
     
       
         
           
               
               
               
             
               
                   
                 TABLE 7 
               
             
            
               
                   
                   
               
               
                   
                 Example 
                 Comparative Example 
               
            
           
           
               
               
               
               
               
               
            
               
                 Division 
                 3-1 
                 3-2 
                 3-1 
                 3-2 
                 3-3 
               
               
                   
               
            
           
           
               
               
               
               
               
               
            
               
                 300% modulus (kgf/cm 2 ) 
                 160 
                 163 
                 145 
                 149 
                 164 
               
            
           
           
               
               
               
               
               
               
               
            
               
                 Viscoelasticity 
                 Tan δ (at 
                 98 
                 99 
                 100 
                 101 
                 96 
               
               
                 properties 
                 0° C., Index) 
               
               
                   
                 Tan δ (at 
                 118 
                 120 
                 100 
                 106 
                 119 
               
               
                   
                 60° C., Index) 
               
            
           
           
               
               
               
               
               
               
            
               
                 Processability 
                 103 
                 101 
                 100 
                 102 
                 73 
               
               
                 properties (Index) 
               
               
                   
               
               
                 * All indexes are values based on Comparative Example 3-1. 
               
            
           
         
       
     
     As shown in Table 7, it was confirmed that Examples 3-1 and 3-2, which used the modified conjugated diene-based polymers according to embodiments of the present invention, showed excellent processability properties and at the same time, excellent tensile properties and viscoelasticity properties when compared with Comparative Examples 3-1 and 3-2. 
     It could be confirmed that Examples 3-1 and 3-2 showed very marked difference in rotation resistance and improved results of tensile properties when compared with Comparative Examples 3-1 and 3-2, and showed equal or better tensile properties, improved viscoelasticity properties and markedly improved processability properties when compared with Comparative Example 3-3. It could be found that these effects were achieved in the Examples due to the use of the functional chain together with a modification initiator and not using a modifier coupled with a functional group, and markedly significantly different processability was shown. 
     Through this, it was confirmed that marked effects not shown in Comparative Example 3-3 were shown in the modified conjugated diene-based polymer of the present invention by being prepared by a preparation method including a step of reacting with a functional chain after modification reaction. Through the effect difference, it could be anticipated that the modified conjugated diene-based polymer of the present invention is a copolymer having a different structure from Comparative Example 3-3, for example, a structure similar to a graft copolymer through the coupling of the functional chain including the repeating unit derived from the N-functional group-containing monomer derived from the functional chain with the non-functional chain of the modified polymer via the functional group derived from a modifier.