Patent Description:
In particular, the present invention relates to a method for producing a modified polydiene by polymerization of a conjugated diene in an organic solvent by using a modified catalyst complex including a lanthanide, an organoaluminum compound, a halogen-containing component, and a maleinized low molecular weight polybutadiene, followed by post-polymerization modification using at least one oligomeric silicate.

The present invention also relates to modified polydiene-based rubber mixtures.

Patent <CIT> discloses a method for producing a polydiene by polymerization of a conjugated diene in the presence of an active catalyst and an amine, where the amine is introduced before <NUM>% of the conjugated diene monomer is polymerized. This technique provides a polydiene with a reactive chain end. In addition, this method includes a variant of an additional step of reacting a functionalizing agent with said reactive chain end.

The amine is introduced to reduce the risk of runaway polymerization and reactor fouling.

However, the presence of an amine in the catalyst complex leads to the formation of a precipitate that prevents the polymerization reaction from proceeding. In addition, one of the components of the catalyst complex is methylaluminoxane, which is characterized by poor storage stability, increases the ash content of the polymer, and, in addition, is an expensive compound.

The active center (together with the growing macromolecule) is known to react with carbonyl groups during post-polymerization and polymerization modification with maleic fragments, which leads to a change in molecular parameters and plastoelastic properties of polybutadienes. At the same time, new phenomena have been discovered. In particular, when a modifier is added directly to the finished catalyst complex (polymerization modification), the modifier not only interrupts the polymerization process, but also provides results that, according to the author of an article, may be considered as close to post-polymerization modification (<NPL>).

However, the article comprises no information on the mechanism of polymer modification when the above catalyst complex is used, and no information on which of the properties of the polymer have been improved. In addition, it is evident that the use of maleinized polybutadiene alone for modification, regardless the time of its introduction, does not provide a polymer with improved processability and manufacturability.

<CIT> discloses a method for producing a low branch content polybutadiene. The proposed method includes: (a) polymerization of butadiene; (b) treatment of the polymer solution obtained upon completion of stage (a) with a coupling agent selected from: (i) polyunsaturated natural oils; (ii) butadiene and/or isoprene oligomers; (iii) butadiene and/or isoprene copolymers with vinylarene monomers; the unsaturated bonds present in compounds (i)-(iii) being at least partially substituted with groups selected from epoxides, anhydrides and esters; (c) recovery of the low branch content polybutadiene obtained upon completion of stage (b).

However, the implementation of the technical solution according to this patent, i.e. terminal post-polymerization modification, leads to a high consumption of maleinized polybutadiene.

<CIT> provides a method for preparation of siloxane-functionalized high <NUM>,<NUM>-cis polybutadiene. The method comprises polymerization of <NUM>,<NUM>-butadiene and subsequent modification with a siloxane compound represented by formulas I or II:
<CHM>
<CHM>
where R<NUM>-R<NUM> are the same or different and include halogen, or C<NUM>-C<NUM> alkyl or aryl group, and n and m are integer of <NUM> to <NUM>.

<CIT> demonstrates that the use of silicon-containing substances (I and II) as a modifier provides polybutadiene with high abrasion resistance, but the resulting rubber is characterized by a high polydispersity value, which negatively affects the properties of rubbers produced from them.

The method, which is closest in technical essence and the achieved result, is a process for the preparation of nano-structured polymers based on conjugated dienes, provided in patent <CIT>. According to the patent, nano-structured polymers based on conjugated dienes are prepared in the presence of catalysts based on rare earth metal compounds, followed by reaction with a nano-coupling agent. The nano-coupling agents are oligomeric silicates of the formula:.

where X is an alkoxy group of the formula OR, where R is a saturated or unsaturated aliphatic hydrocarbon residue having from <NUM> to <NUM> carbon atoms, a cycloaliphatic hydrocarbon residue having from <NUM> to <NUM> carbon atoms, or an aromatic hydrocarbon residue having from <NUM> to <NUM> carbon atoms, and n is an integer greater than <NUM>, preferably greater than <NUM>, particularly preferably greater than <NUM>.

In addition, according to patent <CIT>, the nano-coupling agents can be introduced into the reaction system at any time depending on desired properties of polymers to be produced.

The disadvantage of this invention is a wide polydispersity of the rubbers produced by this process, which negatively affects the properties of rubbers produced from them.

The use of polybutadiene with a linear stereoregular structure makes it possible to obtain rubber mixtures for tires with high physical and mechanical properties (strength, elastic-hysteresis properties (AHS), abrasion, wear resistance, etc.), but at the same time, such polybutadienes are characterized by high viscosity, which negatively affects the processability of rubber mixtures, and high cold flow, which causes problems with isolation and storage of the polymer.

The objective of the present invention is to reduce cold flow values of the polymer and improve the processability of rubber mixtures.

The objective is addressed by a method for producing a modified polydiene (preferably polybutadiene), which comprises the following steps: <NUM>) preparing a catalyst complex including a lanthanide compound, an organoaluminum compound, a halogen-containing component, and a conjugated diene; <NUM>) reacting the catalyst complex prepared in step <NUM>) with a maleinized low molecular weight polybutadiene to produce a modified catalyst complex; <NUM>) subjecting the conjugated diene to polymerization in an organic solvent in the presence of the catalyst complex produced in step <NUM>); and <NUM>) subjecting the resulting polydiene to post-polymerization modification using at least one oligomeric silicate.

The technical result of the present invention is the production of a modified (branched and functionalized) stereoregular polydiene characterized by a narrow molecular weight distribution and a low cold flow. Another result of the invention is the production of rubber mixtures characterized by uniform filler distribution and demonstrating improved manufacturability (low Mooney viscosity) and tear resistance.

According to the present invention, the production of a modified polydiene involves the use of at least two modifying agents, which are in particular maleinized low molecular weight polybutadienes (hereinafter - MPBs) used to modify the catalyst complex and oligomeric silicates used for post-polymerization treatment of the polymerizate.

The MPBs used according to the invention are an adduct of maleic anhydride and a polybutadiene, comprising from <NUM> to <NUM> wt. % anhydride groups based on the total weight of maleinized polybutadiene, and have a molecular weight of <NUM> to <NUM>/mol. Polybutadienes with a molecular weight of more than <NUM>,<NUM>/mol are not low molecular weight compounds; MPBs with a molecular weight of less than <NUM>/mol are currently unknown. The content of anhydride groups is indicated by reference to the currently existing MPBs; however, the content of anhydride groups of more than <NUM> wt. % is theoretically acceptable.

In some embodiments, MPBs can be characterized by a content of anhydride groups of <NUM> to <NUM> wt. % and a molecular weight of <NUM> to <NUM>/mol.

In a preferred embodiment, used MPBs comprise from <NUM> to <NUM> wt. % of anhydride groups and have a molecular weight of <NUM> to <NUM>/mol.

A modified catalyst complex is produced by reaction of MPB with a prepared catalyst complex which includes a lanthanide compound, an organoaluminum compound, a halogen-containing component, and a conjugated diene. This reaction can be carried out in two ways: by introduction of MPB directly into the prepared catalyst complex or by introduction of MPB into charge stock (monomer solution) before the addition of the active catalyst complex. It was unexpectedly found that when the catalyst complex is fed into the charge stock comprising MPB previously introduced therein, the catalyst complex interacts with the MPB to form a modified catalyst complex. A cyclic associate is assumed to be formed in the modified catalyst complex in this case, which has several active sites where the growth of the polymer chain is further possible. According to the authors of the present invention, this provides a branched polymer.

To obtain a modified catalyst complex, MPB is used in an amount of at least <NUM> mol per <NUM> mol of lanthanide. Preferably, the MBP is used in a molar ratio of (<NUM>-<NUM>):<NUM> per lanthanide. The exact dosages of the introduced polybutadiene depend on various factors, including the activity of the catalyst complex and desired properties of the resulting product. It was found that this ratio allows the production of polydiene with optimal low cold flow values and a narrow molecular weight distribution. The mole ratio of <NUM> to <NUM> of MPB per <NUM> mole of lanthanide is most preferable.

With an increase in the MPB dosage over <NUM> mol per <NUM> mol of lanthanide, the polymerization process slows down. A reduction of the MPB dosage below the specified levels does not lead to an improvement in the polymer properties and is not therefore advisable.

Oligomeric silicates used in the post-polymerization treatment have the general formula:
X3-Si-(O-SiX2)n-X, where X is an alkoxy group of the formula OR, where R is a saturated or unsaturated aliphatic hydrocarbon residue comprising <NUM> to <NUM> carbon atoms, a cycloaliphatic hydrocarbon residue comprising <NUM> to <NUM> carbon atoms, or an aromatic hydrocarbon residue comprising <NUM> to <NUM> carbon atoms, and n is an integer greater than <NUM>, preferably greater than <NUM>, particularly preferably greater than <NUM>.

The most preferred compounds according to the claimed method are compounds of formulas:.

(RO)<NUM>Si-O-Si(OR)<NUM>-O-Si(OR)<NUM>,.

(RO)<NUM>Si-O-Si(OR)<NUM>-O-Si(OR)<NUM>-O-Si(OR)<NUM>,.

(RO)<NUM> Si-O-Si(OR)<NUM>-O-Si(OR)<NUM>-O-Si(OR)<NUM>-O-Si(OR)<NUM>,.

(RO)<NUM>Si-O-Si(OR)<NUM>-O-Si(OR)<NUM>-O-Si(OR)<NUM>-O-Si(OR)<NUM>-O-Si(OR)<NUM>.

(RO)<NUM>Si-O-Si(OR)<NUM>-O-Si(OR)<NUM>-O-Si(OR)<NUM>-O-Si(OR)<NUM>-O-Si(OR)<NUM>-O-Si(OR)<NUM>,.

where R is methyl, ethyl, vinyl, propyl, isopropyl, butyl, isobutyl, pentyl, isopentyl, hexyl, isohexyl, octyl, or isooctyl.

Examples of commercially available oligomeric silicates can be ethyl polysilicate (silicon ether) of the formula (OEt)<NUM>-Si-(O-Si(OEt)<NUM>)n-OEt, where n is an integer from <NUM> to <NUM>, with a SiO<NUM> content of <NUM> to <NUM>%; oligomeric vinylsilanes; oligomeric siloxane comprising vinyl and methoxy groups, with a SiO<NUM> content of <NUM>%; oligomeric siloxane comprising vinyl and ethoxy groups, with a SiO<NUM> content of <NUM>%, oligomeric siloxane comprising vinyl, propyl, and ethoxy groups.

The content of oligomeric silicates used according to the invention per <NUM> of polymer can be from <NUM> to <NUM>. It is preferable to use from <NUM> to <NUM> per <NUM> of polymer. These dosages allow the preparation of polydiene with optimal values of plasticity and cold flow; rubber mixtures based on these polymers are characterized by uniform filler distribution in the rubber matrix and high strength properties.

With an increase in the proposed dosage, a jump in Mooney viscosity is observed and polydispersity widens, which is acceptable for a potential polymer consumer in some cases, and unacceptable in others, and depends on the field and methods of application of the resulting polymer. With a decrease in dosages of oligomeric silicates, changes in the entire complex of rubber properties are insignificant.

The mechanism of modification by oligomeric silicates is such that they enter into reaction with "living" ends of the polymer, and at the step of degassing, the groups of oligomeric silicates react with each other, and the condensation results in the formation of high-molecular structures.

To obtain the catalyst complex according to the invention, compounds that can be used as lanthanide compounds comprise at least one atom of a lanthanide selected from the group consisting of lanthanum, neodymium, cerium, praseodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium. It is preferable to use neodymium.

Lanthanide-containing compounds include, but are not limited to, carboxylates, organophosphates, organophosphonates, organophosphinates, carbamates, dithiocarbamates, xanthogenates, β-diketonates, halides, oxyhalides, and alcoholates.

Neodymium carboxylates include neodymium formate, neodymium acetate, neodymium acrylate, neodymium methacrylate, neodymium valerate, neodymium gluconate, neodymium citrate, neodymium fumarate, neodymium lactate, neodymium maleate, neodymium oxalate, neodymium <NUM>-ethylhexanoate, neodymium neodecanoate (trade name neodymium versatate), neodymium naphthenate, neodymium stearate, neodymium oleate, neodymium benzoate and neodymium picolinate.

Neodymium organophosphates include neodymium dibutyl phosphate, neodymium diphenyl phosphate, neodymium dihexyl phosphate, neodymium diheptyl phosphate, neodymium dioctyl phosphate, neodymium bis(<NUM>-methylheptyl)phosphate, neodymium bis(<NUM>-ethylhexyl)phosphate, neodymium didecyl phosphate, neodymium dodecyl phosphate, neodymium dioctadecyl phosphate, neodymium bis(n-nonylphenyl)phosphate, neodymium butyl(<NUM>-ethylhexyl)phosphate, neodymium (<NUM>-methylphenyl)(<NUM>-ethylhexyl)phosphate, and neodymium (<NUM>-ethylhexyl)(n-nonylphenyl)phosphate.

Neodymium organophosphonates include neodymium butyl phosphonate, neodymium pentyl phosphonate, neodymium hexyl phosphonate, neodymium heptyl phosphonate, neodymium octyl phosphonate, neodymium (<NUM>-methylheptyl)phosphonate, neodymium (<NUM>-ethylhexyl)phosphonate, neodymium decyl phosphonate, neodymium dodecyl phosphonate, neodymium octadecyl phosphonate, neodymium oleyl phosphonate, neodymium phenyl phosphonate, neodymium (n-nonylphenyl)phosphonate, neodymium butyl(butylphosphonate), neodymium pentyl(pentylphosphonate), neodymium hexyl(hexylphosphonate), neodymium heptyl(heptylphosphonate), neodymium octyl(octylphosphonate), neodymium (<NUM>-methylheptyl)((<NUM>-methylheptyl)phosphonate), neodymium (<NUM>-ethylhexyl)((<NUM>-ethylhexyl)phosphonate, neodymium decyl(decylphosphonate), neodymium dodecyl(dodecylphosphonate), neodymium octadecyl(octadecylphosphonate), neodymium oleyl(oleylphosphonate), neodymium phenyl(phenylphosphonate), neodymium (n-nonylphenyl)((n-nonylphenyl)phosphonate), neodymium butyl(<NUM>-ethylhexyl)phosphonate, neodymium (<NUM>-ethylhexyl)(butylphosphonate), neodymium (<NUM>-methylheptyl)(<NUM>-ethylhexyl)phosphonate, neodymium (<NUM>-ethylhexyl)((<NUM>-methylheptyl)phosphonate), neodymium (<NUM>-ethylhexyl)((n-nonylphenyl)phosphonate), and neodymium (p-nonylphenyl)((<NUM>-ethylhexyl)(phosphonate).

Neodymium organophosphinates include neodymium butyl phosphinate, neodymium pentyl phosphinate, neodymium hexyl phosphinate, neodymium heptyl phosphinate, neodymium octyl phosphinate, neodymium (<NUM>-methylheptyl)phosphinate, neodymium (<NUM>-ethylhexyl)phosphinate, neodymium decylphosphinate, neodymium dodecylphosphinate, neodymium octadecylphosphinate, neodymium oleylphosphinate, neodymium phenylphosphinate, neodymium (n-nonylphenyl)phosphinate, neodymium dibutyl phosphinate, neodymium dipentyl phosphinate, neodymium dihexyl phosphinate, neodymium diheptyl phosphinate, neodymium dioctyl phosphinate, neodymium bis(<NUM>-methylheptyl)phosphinate, neodymium bis(<NUM>-ethylhexyl)phosphinate, tris-[bis(<NUM>-ethylhexyl)phosphate]neodymium, neodymium didecyl phosphinate, neodymium didodecyl phosphinate, neodymium dioctadecyl phosphinate; neodymium dioleyl phosphinate, neodymium diphenyl phosphinate, neodymium bis(n-nonylphenyl)phosphinate, neodymium butyl(<NUM>-ethylhexyl)phosphinate, neodymium (<NUM>-methylheptyl)(<NUM>-ethylhexyl)phosphinate, and neodymium (<NUM>-ethylhexyl)(n-nonylphenyl)phosphinate.

The use of neo-acid carboxylates is most preferable. The structure of neo-acids comprise a trialkyl carboxylic acid (branched α,α'-carboxylic acid) moiety. Neo-acid derivatives, which are more soluble in hydrocarbon solvents, are alkylated faster and more completely, which leads to the formation of more active catalyst compounds.

It is preferable to use neodymium carboxylates and phosphates, wherein tris-[bis(<NUM>-ethylhexyl)phosphate]neodymium, neodymium neodecanoate, tris-[(<NUM>-ethyl)hexanoate]neodymium, gadolinium versatate, or praseodymium versatate are most preferable.

The organoaluminum compounds which can be used in the method according to the present invention include trialkylaluminum, triphenylaluminum or dialkylaluminum hydrides, alkylaluminum dihydrides and mixtures thereof, in particular trimethylaluminum, triethylaluminum, tri-n-propylaluminum, triisopropylaluminum, tri-n-butylaluminum, triisobutylaluminum, tri-tert-butylaluminum, triphenylaluminum, trihexylaluminum, tricyclohexylaluminum, trioctylaluminum, diethylaluminum hydride, di-n-propylaluminum hydride, di-n-butylaluminum hydride, diisobutylaluminum hydride, dihexylaluminum hydride, diisohexylaluminum hydride, dioctylaluminum hydride, diisooctylaluminum hydride, phenylethylaluminum hydride, phenyl-n-propylaluminum hydride, phenylisopropylaluminum hydride, pfenyl-n-butylaluminum hydride, phenylisobutylaluminum hydride, benzylethylaluminum hydride, benzyl-n-butylaluminum hydride, benzylisobutylaluminum hydride, benzylisopropylaluminum hydride, etc. and mixtures thereof.

The use of aluminum alkyls or alkylaluminum hydrides or mixtures thereof are preferable.

Triethylaluminum, triisobutylaluminum, diisobutylaluminum hydride or mixtures thereof are most preferable.

The conjugated dienes which can be used in the method according to the invention include <NUM>,<NUM>-butadiene, isoprene, <NUM>,<NUM>-dimethyl-<NUM>,<NUM>-butadiene, <NUM>,<NUM>-pentadiene (piperylene), <NUM>-methyl-<NUM>-ethyl-<NUM>,<NUM>-butadiene, <NUM>-methyl-<NUM>,<NUM>-pentadiene, <NUM>-methyl-<NUM>-ethyl-<NUM>,<NUM>-pentadiene, <NUM>-methyl-<NUM>,<NUM>-pentadiene, <NUM>,<NUM>-hexadiene, <NUM>-methyl-<NUM>,<NUM>-hexadiene, <NUM>,<NUM>-heptadiene, <NUM>-methyl-<NUM>,<NUM>-heptadiene, <NUM>,<NUM>-octadiene, <NUM>-butyl-<NUM>,<NUM>-octadiene, <NUM>,<NUM>-dimethyl-<NUM>,<NUM>-hexadiene, <NUM>,<NUM>-diethyl-<NUM>,<NUM>-octadiene, phenyl-<NUM>,<NUM>-butadiene, <NUM>,<NUM>-diethyl-<NUM>,<NUM>-butadiene, <NUM>,<NUM>-di-n-propyl-<NUM>,<NUM>-butadiene, <NUM>-methyl-<NUM>-isopropyl-<NUM>,<NUM>-butadiene.

<NUM>,<NUM>-Butadiene, isoprene, piperylene are most preferable as conjugated dienes.

Compounds which can be used as a halogen-containing component include dimethylaluminum chloride, diethylaluminum chloride, diisobutylaluminum chloride, dimethylaluminum bromide, diethylaluminum bromide, diisobutylaluminum bromide, dimethylaluminum fluoride, diethylaluminum fluoride, diisobutylaluminum fluoride, dimethylaluminum iodide, diethylaluminum iodide, diisobutylaluminum iodide, methylaluminum dichloride, ethylaluminum dichloride, methylaluminum dibromide, ethylaluminum dibromide, methylaluminum difluoride, ethylaluminum difluoride, methylaluminum sesquichloride, ethylaluminum sesquichloride, isobutylaluminum sesquichloride, as well as trimethyltin chloride, trimethyltin bromide, triethyltin chloride, triethyltin bromide, di-tert-butyltin dichloride, di-tert-butyltin dibromide, dibutyltin dichloride, dibutyltin dibromide, tributyltin chloride and tributyltin bromide and the like.

The use of ethylaluminum sesquichloride, ethylaluminum dichloride or diethylaluminum chloride as a halogen-containing compound is preferable.

In one embodiment of the invention, a catalyst complex used for polymerization comprises (A) a lanthanide compound, (B) an organoaluminum compound, (C) a conjugated diene, and (D) a halogen-containing component at a (A):(B):(C):(D) molar ratio equal to <NUM>:(<NUM>-<NUM>):(<NUM>-<NUM>):(<NUM>-<NUM>).

The preferred molar ratio of the components in the catalyst complex is (A):(B):(C):(D) = <NUM>:(<NUM>-<NUM>):(<NUM>-<NUM>):(<NUM>-<NUM>).

The most preferred molar ratio of the components in the catalyst complex is (A):(B):(C):(D) = <NUM>:(<NUM>-<NUM>):(<NUM>-<NUM>):(<NUM>-<NUM>).

The polymerization solvent is an inert organic solvent (inert solvents that do not have a pronounced proton affinity and are not able to donate their protons, and do not change acidic, basic or amphoteric properties of chemical compounds dissolved in them), including aliphatic hydrocarbons used individually or in mixtures with each other, in particular such as butane, pentane, hexane, heptane; alicyclic hydrocarbons, namely cyclopentane, cyclohexane; mono-olefins, such as <NUM>-butene, <NUM>-butene, or mixtures thereof; aromatic hydrocarbons, in particular such as benzene, toluene, xylene.

According to the proposed method, the most preferred solvent is a hydrocarbon solvent, which is a cyclohexane:hexane mixture or a cyclohexane:nefras (industrial hexane-heptane paraffin hydrocarbon fraction of dearomatized catalytic reforming gasoline with boiling point limits between <NUM> and <NUM>) mixture at a ratio of (<NUM>-<NUM>)÷(<NUM>-<NUM>).

The process of preparing polydiene is carried out batchwise or continuously in a hydrocarbon solvent by feeding the reactor/autoclave with a hydrocarbon charge stock consisting of a monomer and a solvent, and a catalyst complex pre-mixed with the solvent, comprising a lanthanide compound, an organoaluminum compound, a conjugated diene, and a halogen-containing organic compound. The monomer concentration in the solvent is typically from <NUM> to <NUM>% by weight, preferably from <NUM> to <NUM>%. A concentration below <NUM>% leads to a decrease in the energy efficiency of the process, whereas a concentration above <NUM>% leads to an increase in the polymerizate viscosity and, consequently, an increase in the energy consumption during isolation and drying of rubber.

The catalyst complex can be prepared by introducing an organoaluminum compound (most preferably triisobutylaluminum, triethylaluminum, diisobutylaluminum hydride or a mixture thereof), a lanthanide compound (most preferably a carboxylate, in particular, neodymium neodecanoate or tris-[bis-(<NUM>-ethylhexyl)phosphate]neodymium) into a solution of a conjugated diene (most preferably <NUM>,<NUM>-butadiene) in an organic (preferably aliphatic) solvent; aging the resulting mixture for <NUM> to <NUM> hours at a temperature of <NUM>±<NUM>, followed by the addition of a halogen-containing compound (most preferably ethylaluminum sesquichloride, ethylaluminum dichloride, diethylaluminum chloride or mixtures thereof), and aging the resulting mixture for <NUM> to <NUM> hours at a temperature of <NUM>±<NUM>, followed by the addition of a branching agent, MPB, at a molar ratio of catalyst complex components, in particular (A) lanthanide, (B) organoaluminum compound, (C) conjugated diene, (D) halogen-containing component, (D) branching agent, (A):(B):(C):(D):(D), equal to <NUM>:(<NUM>-<NUM>):(<NUM>-<NUM>):(<NUM>-<NUM>) (<NUM>-<NUM>).

The reaction of MPB with the catalyst complex is carried out with stirring for <NUM>-<NUM> minutes. A longer mixing time is not required since this time is sufficient for the formation of an active complex. The stirring is carried out at a temperature of from <NUM> to <NUM>. Pressure is not required to be controlled. The polymerization process is carried out at a temperature of <NUM>-<NUM>.

The time of polymerization can be from <NUM> to <NUM> hours. The monomer conversion reaches <NUM>-<NUM>%.

After reaching the monomer conversion of <NUM>-<NUM>%, a control sample is taken, and a modifier is fed into the remaining polymerizate - at least one oligomeric silicate. The resulting mixture is thoroughly stirred for <NUM> minutes to <NUM> hours at a temperature of <NUM>-<NUM>. At a temperature below <NUM>, the viscosity of the polymer will increase, which is undesirable because of inevitable difficulties in its isolation and processing. At the same time, the end groups of the polymer chain tend to lose their activity at a temperature above <NUM>, and as a consequence it can be very difficult to achieve a high degree of modification of the polymer.

Oligomeric silicates react with the polymer at the active ends of its chain.

The time of modification may preferably be from <NUM> minutes to <NUM> hours, most preferably from <NUM> minutes to <NUM> hour.

Upon completion of the modification, the polymerization products are stabilized with an antioxidant solution in an amount of <NUM> to <NUM> wt. % per polymer and degassed with water. If during degassing the polymer is in contact with water, the macromolecules of oligomeric silicates attached to the polymer interact with each other, as well as with free macromolecules.

The Mooney viscosity of the rubber prepared according to the invention is from <NUM> to <NUM> arbitrary Mooney units before modification and from <NUM> to <NUM> arbitrary Mooney units after modification; the polydispersity index of the prepared polydienes is in the range of <NUM> to <NUM>, cold flow is in the range of <NUM> to <NUM>/h, plasticity is in the range of <NUM> to <NUM>, and elastic recovery is in the range of <NUM> to <NUM>.

Rubber mixtures based on the obtained polydienes are prepared according to standard formulations as presented in Table <NUM> and are characterized by low Mooney viscosity of the rubber mixtures and improved tear resistance.

In a particular embodiment of the invention, the method defined in any one of claims <NUM>-<NUM> is characterized in that:.

Exemplary embodiments of the present invention are described below. One of ordinary skill in the art would appreciate that the invention is not limited only to the examples presented, and the same effect can be achieved in other embodiments without going beyond the essence of the claimed invention.

Test methods used to evaluate the properties of polymers prepared according to the claimed method are further described below.

Polymerization was carried out under a nitrogen atmosphere under conditions excluding air and moisture. Dry and oxygen-free commercial hexane was used as a solvent. The polymerization was carried out in an autoclave with a working volume that, depending on the load, ranged from <NUM> to <NUM> liters.

Conversion was determined gravimetrically. For this, samples of a polymer solution were weighed immediately after sampling (they comprised the solvent and monomer) and after drying, which was carried out at <NUM> in a vacuum oven.

Mooney viscosity ML <NUM>+<NUM> (<NUM>) was measured using an Alpha device equipped with a massive rotor for <NUM> minutes at <NUM> (the samples were preheated for one minute).

A solution of diisobutylaluminum hydride [Al(C<NUM>H<NUM>)<NUM>H, hereinafter referred to as DIBAG] in hexane, a solution of ethylaluminum sesquichloride [Al<NUM>(C<NUM>H<NUM>)<NUM>Cl<NUM>, hereinafter referred to as EASC] in hexane in an equimolar amount to neodymium versatate, and a solution of neodymium versatate [NdV<NUM>] in hexane were added with stirring to a solution of <NUM>,<NUM>-butadiene (BD) in technical hexane in a concentration of <NUM> wt. %, loaded into a dry and nitrogen-filled <NUM> steel reactor. The reaction mixture was heated to <NUM>. Upon completion of the polymerization (<NUM> minutes after its start), a sample of polymer was taken. Then, a solution of a modifying reagent, which was ethyl polysilicate, polymerized tetraethyl orthosilicate with a SiO<NUM> content of <NUM>-<NUM>% (A), in <NUM> of hexane was added with stirring using a burette. The amount of ethyl polysilicate was <NUM> per <NUM> of polymer. The characteristics of the polymer samples before and after polymerization are shown in Table <NUM>. After one hour, the reaction was stopped by adding <NUM> of water and the reaction products were stabilized by adding <NUM> of Irganox <NUM> stabilizer dissolved in <NUM> of hexane.

The polymer was precipitated with <NUM> liters of water-containing ethanol and dried at <NUM> in a vacuum oven.

A catalyst complex including neodymium neodecanoate [NdV<NUM>], butadiene (BD), diisobutylaluminum hydride (DIBAH), ethylaluminum sesquichloride (EASC) was prepared, in an aliphatic solvent, which was a mixture of cyclohexane/nefras in a mass ratio of <NUM>/<NUM>. The ratio of components in the catalyst complex was BD:Nd:DIBAG:EASC = <NUM>:<NUM>:<NUM>:<NUM>. The aging time of the complex was <NUM> hours at a temperature of <NUM>. Before being fed to the polymerization reactor, MPB with a molecular weight of <NUM> was fed directly into the catalyst complex in an amount of <NUM> mol per neodymium.

<NUM> of a butadiene solution (<NUM>%) and <NUM> of a solvent, which was a cyclohexane/nefras mixture in a mass ratio of <NUM>/<NUM>, were loaded into a <NUM> reactor equipped with a stirrer and a jacket for heat removal, the mixture was heated to <NUM>, then the catalyst system (<NUM>) was fed. The polymerization reaction temperature was <NUM>.

After reaching a monomer conversion of <NUM>%, <NUM> of the polymerizate were taken for analysis, and the obtained data were compared with those of a modified polymer. A phenolic nonstaining antioxidant was introduced into the sampled polymerizate, degassed, and dried on a roller. Then, its physical and mechanical parameters and molecular weight characteristics were determined.

A modifier, ethyl polysilicate with a SiO<NUM> content of <NUM>-<NUM>% (A), was added to the remaining polymerizate; the dosage of the modifier was <NUM> per <NUM> of polymer. The modification process was carried out with constant stirring for <NUM> at a temperature of <NUM>. Then, a phenolic nonstaining antioxidant was added. The mass fraction of the antioxidant was <NUM>%. The polymer was degassed and dried on rollers, and its physical and mechanical parameters and molecular weight characteristics were determined (see Table <NUM>).

The example is similar to example <NUM>, with the difference being the use of MPB with a molecular weight of <NUM> in an amount of <NUM> mol per neodymium and an oligomeric siloxane comprising vinyl and methoxy groups, with a SiO<NUM> content of <NUM>% (B). The modifier dosage was <NUM> per <NUM> polymer.

The example is similar to example <NUM>, with the difference that instead of neodymium neodecanoate, tris-[bis(<NUM>-ethylhexyl)phosphate] was used; the dosage of MPB was <NUM> mol per neodymium, the oligomeric silicate was ethyl polysilicate (A), and the modifier dosage was <NUM> per <NUM> of polymer.

The example is similar to example <NUM>, with the difference that the chlorinating agent in the catalyst complex was diethylaluminum sesquichloride (DEAC). The ratio of components in the catalyst complex was BD:Nd:DIBAG:DEAC = <NUM>:<NUM>:<NUM>:<NUM>. The aging time of the complex was <NUM> hours at a temperature of <NUM>. Before being fed to the polymerization reactor, MPB with a molecular weight of <NUM> was fed directly into the catalyst complex in an amount of <NUM> mol per neodymium, and the dosage of oligomeric silicate, ethyl polysilicate (A), was <NUM> per <NUM> of polymer.

The example is similar to example <NUM>, with the difference being the use of triisobutylaluminum (TIBA) and DIBAG in the catalyst complex. The ratio of components in the catalyst complex was BD:Nd:TIBA:DIBAG:EASC = <NUM>:<NUM>:<NUM>:<NUM>:<NUM>. The aging time of the complex was <NUM> hours at a temperature of <NUM>. Before being fed to the polymerization reactor, MPB was fed directly into the catalyst complex in a dosage of <NUM> mol per neodymium, the dosage of oligomeric silicate, ethyl polysilicate (A), was <NUM>/kg of polymer.

The example is similar to example <NUM>, with the difference that MPB was used in an amount of <NUM> mol per neodymium, and the dosage of oligomeric silicate (B) was <NUM> per <NUM> of polymer.

The example is similar to example <NUM>, with the difference being the use of triethylaluminum (TEA) and DIBAG in the catalyst complex. The ratio of components in the catalyst complex was BD:Nd:TEA:DIBAG:DEAH = <NUM>:<NUM>:<NUM>:<NUM>:<NUM>. The aging time of the complex was <NUM> hours at a temperature of <NUM>. Before being fed to the polymerization reactor, MPB was fed directly into the catalyst complex, and the dosage of oligomeric silicate (A) was <NUM> per <NUM> of polymer.

The example is similar to example <NUM>, with the difference being the use of GdV<NUM>, gadolinium versatate, in the catalyst complex. The ratio of components in the catalyst complex was BD:Gd:DIBAG:EACX = <NUM>:<NUM>:<NUM>:<NUM>. The aging time of the complex was <NUM> hours at a temperature of <NUM>. Before being fed to the polymerization reactor, MPB was fed directly into the catalyst complex at a dosage of <NUM> mol per gadolinium; an oligomeric siloxane containing vinyl and ethoxy groups, with a SiO<NUM> content of <NUM>% (C) was used at a dosage of <NUM> per <NUM> of polymer.

The example is similar to example <NUM>, with the difference being the use of DEAC in the catalyst complex. The ratio of components in the catalyst complex was BD:Gd:DIBAG:DEAH = <NUM>:<NUM>:<NUM>:<NUM>. The aging time of the complex was <NUM> hours at a temperature of <NUM>. Before being fed to the polymerization reactor, MPB was fed directly into the catalyst complex at a dosage of <NUM> mol per lanthanide, the dosage of oligomeric silicate (C) was <NUM> per <NUM> of polymer.

The example is similar to example <NUM>, with the difference being the use of TEA and DIBAG in the catalyst complex. The ratio of components in the catalyst complex was BD:Gd:TEA:DIBAG:DEAH = <NUM>:<NUM>:<NUM>:<NUM>::<NUM>. The aging time of the complex was <NUM> hours at a temperature of <NUM>. Before being fed to the polymerization reactor, MPB with a molecular weight of <NUM> was fed directly into the catalyst complex at a dosage of <NUM> mol per lanthanide, and the dosage of oligomeric silicate (C) was <NUM> per <NUM> of polymer.

The example is similar to example <NUM>, with the difference being the use of neodymium tris-[(<NUM>-ethyl)hexanoate] (NdEh<NUM>) in the catalyst complex. The ratio of components in the catalyst complex was BD:Nd:TEA:DIBAG:DEAH = <NUM>:<NUM>:<NUM>:<NUM>:<NUM>. The aging time of the complex was <NUM> hours at a temperature of <NUM>. Before being fed to the polymerization reactor, MPB with a molecular weight of <NUM> was fed directly into the catalyst complex at a dosage of <NUM> mol per lanthanide, the dosage of oligomeric silicate (D), which was oligomeric siloxane comprising vinyl, propyl and ethoxy groups, was <NUM> per <NUM> of polymer.

The example is similar to example <NUM>, with the difference being the use of TIBA and EASC in the catalyst complex. The ratio of components in the catalyst complex was BD:Nd:TIBA:DIBAG:EASC = <NUM>:<NUM>:<NUM>:<NUM>:<NUM>. The aging time of the complex was <NUM> hours at a temperature of <NUM>. Before being fed to the polymerization reactor, MPB with a molecular weight of <NUM> was fed directly into the catalyst complex at a dosage of <NUM> mol per lanthanide, and the dosage of oligomeric silicate (D) was <NUM> per <NUM> of polymer.

The example is similar to example <NUM>, with the difference being the use of DIBAG in the catalyst complex. The ratio of components in the catalyst complex was BD:Nd:DIBAG:EASC = <NUM>:<NUM>:<NUM>:<NUM>:<NUM>. The aging time of the complex was <NUM> hours at a temperature of <NUM>. Before being fed to the polymerization reactor, MPB with a molecular weight of <NUM> was fed directly into the catalyst complex at a dosage of <NUM> mol per lanthanide, and the dosage of oligomeric silicate (D) was <NUM> per <NUM> of polymer.

The example is similar to example <NUM>, with the difference being the use of praseodymium versatate (PrV3) in the catalyst complex. The ratio of components in the catalyst complex was BD:Pr:DIBAG:EASC = <NUM>:<NUM>:<NUM>:<NUM>:<NUM>. The aging time of the complex was <NUM> hours at a temperature of <NUM>. Before being fed to the polymerization reactor, MPB with a molecular weight of <NUM> was fed directly into the catalyst complex at a dosage of <NUM> mol per lanthanide, and the dosage of oligomeric silicate (A) was <NUM> per <NUM> of polymer.

The example is similar to example <NUM>, with the difference being the use of praseodymium versatate (PrV3) in the catalyst complex. Before being fed to the polymerization reactor, MPB with a molecular weight of <NUM> was fed directly into the catalyst complex at a dosage of <NUM> mol per lanthanide, and the dosage of oligomeric silicate (B) was <NUM> per <NUM> of polymer.

List of the abbreviations used in Table <NUM>:.

The polymers obtained in Examples <NUM> and <NUM> of the invention were tested in rubber mixtures prepared according to the formulation presented in Table <NUM>. The test results in comparison with the prototype are given in Table <NUM>.

Claim 1:
A method for producing a modified polydiene by polymerization of a conjugated diene in an organic solvent, the method comprising the following steps: <NUM>) preparing a catalyst complex including a lanthanide compound, an organoaluminum compound, a halogen-containing component, and a conjugated diene; <NUM>) reacting the catalyst complex prepared in step <NUM>) and a maleinized low molecular weight polybutadiene to produce a modified catalyst complex, wherein the maleinized low molecular weight polybutadiene is used in an amount of at least <NUM> mol per <NUM> mol of lanthanide; <NUM>) subjecting the conjugated diene to polymerization using the modified catalyst complex produced in step <NUM>) in the organic solvent; <NUM>) subjecting the resulting polydiene to post-polymerization modification using at least one oligomeric silicate.