Patent Description:
Acrylonitrile-butadiene-styrene (hereinafter referred to as "ABS-based") resins are widely used in various fields, such as automobile products, electrical/electronic products, and office equipment due to excellent rigidity, chemical resistance, processability, and mechanical strength thereof and an aesthetically pleasing appearance thereof. However, since ABS-based resins are prepared using a butadiene rubber polymer, there is a limitation that ABS-based resins are not suitable as outdoor materials due to weak weather resistance thereof.

To solve this problem and obtain a thermoplastic resin having excellent physical properties, weather resistance, and aging resistance, acrylonitrile-styrene-acrylate (hereinafter referred to as "ASA-based") resins have been developed using a crosslinked alkyl (meth)acrylate rubber polymer not containing ethylenically unsaturated polymers that promote aging caused due to ultraviolet rays in a graft copolymer. ASA-based resins have excellent weather resistance and aging resistance, and thus are used in various fields, such as automobiles, ships, leisure goods, building materials, and gardening goods.

Technology for providing a heat-resistant ASA-based resin using an alkyl-substituted styrene-based monomer has been developed. However, since the alkyl-substituted styrene-based monomer is included, glass transition temperature is increased. Accordingly, weather resistance, heat resistance, and scratch resistance are improved, but refractive index is significantly increased, resulting in deterioration in colorability. Thus, there is a limitation in implementing blackness (Color L).

In addition, in this technology using the alkyl-substituted styrene-based monomer, bulk polymerization is used. In this case, product yield is reduced due to high viscosity, and generation of residual oligomers is increased due to decomposition of a copolymer, thereby degrading heat resistance.

Therefore, research on a thermoplastic resin composition having improved colorability, processability, and scratch resistance and a low residual oligomer content while maintaining weather resistance and heat resistance and a method of preparing the thermoplastic resin composition is in progress.

<CIT>
<CIT> discloses a thermoplastic resin composition, comprising: a copolymer comprising a (meth)acrylate-based monomer, an aromatic vinyl-based monomer, and a maleimide-based monomer; and a graft copolymer comprising an acrylic-based rubber polymer, an aromatic vinyl-based monomer, and a vinyl cyanide-based monomer, having an average particle diameter from <NUM> to <NUM>.

Therefore, the present invention has been made in view of the above problems, and it is one object of the present invention to provide a thermoplastic resin composition having excellent colorability, processability, and scratch resistance and having a low residual oligomer content while having excellent weather resistance and heat resistance.

It is another object of the present invention to provide a method of preparing the thermoplastic resin composition.

It is yet another object of the present invention to provide a molded article manufactured using the thermoplastic resin composition.

In accordance with one aspect of the present invention, provided is a thermoplastic resin composition comprising:.

In accordance with another aspect of the present invention, provided is a method of preparing a thermoplastic resin composition, the method comprising:.

In accordance with yet another aspect of the present invention, provided is a molded article manufactured using the above-described thermoplastic resin composition.

According to the present invention, there is an effect of providing a thermoplastic resin composition having excellent colorability, processability, and scratch resistance and having a low residual oligomer content while having excellent weather resistance and heat resistance, a method of preparing the thermoplastic resin composition, and a molded article including the thermoplastic resin composition.

Therefore, the thermoplastic resin composition and the molded article according to the present invention may be applied to various industrial fields.

Hereinafter, the present invention will be described in more detail to aid in understanding of the present invention.

In this description, a polymer comprising a certain compound means a polymer prepared by polymerizing including the compound, a polymer polymerized by using the compound, and a polymer including a unit in the polymer is derived from the compound.

In this description, heat resistance may be measured by various methods known in the art, and unless otherwise specified, heat resistance refers to a glass transition temperature (Tg) measured using a differential scanning calorimeter (manufacturer: Ta Instruments, product name: DISCOVERY DSC25).

When a copolymer has a glass transition temperature (Tg) of <NUM> or higher, the copolymer may be classified as a heat-resistant copolymer.

In addition, in this description, average particle diameter may be measured by dynamic light scattering. Specifically, the average particle diameter of a specimen in a latex form may be measured in a Gaussian mode using a particle size distribution analyzer (Nicomp <NUM>). In a particle size distribution measured by dynamic light scattering, an arithmetic average particle diameter may mean a scattering intensity average particle diameter.

As a specific measurement example, a sample is prepared by diluting <NUM> of latex (TSC: <NUM> to <NUM> wt%) <NUM>,<NUM> to <NUM>,<NUM>-fold with distilled water, i.e., a sample is diluted appropriately so as not to deviate significantly from an intensity setpoint of <NUM> and is placed in a glass tube. Then, the average particle diameter of the sample is measured using a flow cell in auto-dilution in a measurement mode of dynamic light scattering/intensity <NUM>/intensity-weight Gaussian analysis. At this time, setting values are as follows: temperature: <NUM>; measurement wavelength: <NUM>; and channel width: <NUM>µsec.

In this description, weight average molecular weight may be measured using tetrahydrofuran (THF) as an eluate through gel permeation chromatography (GPC, Waters Breeze). In this case, weight average molecular weight is obtained as a relative value to a polystyrene standard (PS) specimen. Specifically, the weight average molecular weight is a weight average molecular weight (Mw) converted based on polystyrene by gel permeation chromatography (GPC, PL GPC220, Agilent Technologies).

Specifically, a polymer to be measured is dissolved in tetrahydrofuran to a concentration of <NUM> %, and <NUM>µl of the dissolved sample is injected into a gel permeation chromatograph (GPC) at a flow rate of <NUM>/min. At this time, analysis is performed at a sample concentration of <NUM>/mL (<NUM>µl injection) at <NUM>. In this case, two columns (PLmixed B, Waters Co. ) are connected, and an RI detector (<NUM>, Agilent Waters Co. At this time, measurement is performed at <NUM>, and data is processed using ChemStation.

In this description, the composition ratio of a (co)polymer may mean the content of units constituting the (co)polymer, or may mean the content of units input during polymerization of the (co)polymer.

In this description, unless otherwise defined, "content" means weight.

The present inventors confirmed that, when two types of graft copolymers each including rubber having different average particle diameters and a styrene-based copolymer including a (meth)acrylate-based monomer, astyrene monomer, and a maleimide-based monomer, formed by polymerizing a (meth)acrylate monomer mixture, and having a residual oligomer content below a specific value were mixed within a predetermined content range, all of heat resistance, weather resistance, colorability, processability, and scratch resistance were improved. Based on these results, the present inventors conducted further studies to complete the present invention.

A thermoplastic resin composition according to one embodiment of the present invention includes a styrene-based copolymer comprising a (meth)acrylate-based monomer, a styrene monomer, and a maleimide-based monomer; a first graft copolymer comprising ng an acrylic-based rubber polymer, an aromatic vinyl-based monomer, and a vinyl cyanide-based monomer; and a second graft copolymer comprising an acrylic-based rubber polymer, an aromatic vinyl-based monomer, and a vinyl cyanide-based monomer. In this case, the styrene-based copolymer has a residual oligomer content of <NUM> % by weight or less, and the acrylic-based rubber polymer of the first graft copolymer and the acrylic-based rubber polymer of the second graft copolymer have different average particle diameters. In this case, colorability, processability, and scratch resistance may be improved while maintaining weather resistance and heat resistance.

Hereinafter, each component of the thermoplastic resin composition of the present invention will be described in detail.

The styrene-based copolymer may be a heat-resistant copolymer prepared by polymerizing a monomer mixture including a (meth)acrylate-based monomer, a styrene monomer, and a maleimide-based monomer.

In this case, each monomer becomes a unit of the heat-resistant copolymer.

The styrene-based copolymer may improve the colorability, heat resistance, and scratch resistance of a thermoplastic resin composition. In addition, when the styrene-based copolymer includes a (meth)acrylate-based monomer, the weather resistance of a thermoplastic resin composition may be improved.

The monomer mixture, i.e., styrene copolymer, may include <NUM> to <NUM> % by weight of the (meth)acrylate-based monomer, <NUM> to <NUM> % by weight of the styrene monomer, and <NUM> to <NUM> % by weight of the maleimide-based monomer. Preferably, the monomer mixture includes <NUM> to <NUM> % by weight of the (meth)acrylate-based monomer, <NUM> to <NUM> % by weight of the styrene monomer, and <NUM> to <NUM> % by weight of the maleimide-based monomer. Within this range, a styrene-based copolymer having a low refractive index and a high glass transition temperature may be prepared.

In addition, when the styrene-based copolymer is applied to a thermoplastic resin composition, in addition to colorability and heat resistance, the scratch resistance and weather resistance of the thermoplastic resin composition may be improved.

In this case, when a small amount of the (meth)acrylate-based monomer is included, a styrene-based copolymer having a high refractive index is prepared. When such a styrene-based copolymer is applied to a thermoplastic resin composition, the colorability of the thermoplastic resin composition may be reduced. On the other hand, when an excess of the (meth)acrylate-based monomer is included, the styrene monomer and the maleimide-based monomer are included in relatively small amounts. Accordingly, a styrene-based copolymer having a low glass transition temperature may be prepared. When such a styrene-based copolymer is applied to a thermoplastic resin composition, the heat resistance and scratch resistance of the thermoplastic resin composition may be deteriorated.

In addition, when a small amount of the maleimide-based monomer is included, a styrene-based copolymer having a low glass transition temperature is prepared. When such a styrene-based copolymer is applied to a thermoplastic resin composition, the heat resistance of the thermoplastic resin composition may be deteriorated. When an excess of the maleimide-based monomer is included, the (meth)acrylate-based monomer and the styrene monomer are included in relatively small amounts. Thus, a styrene-based copolymer having a high refractive index may be prepared. When such a styrene-based copolymer is applied to a thermoplastic resin composition, the colorability and scratch resistance of the thermoplastic resin composition may be deteriorated.

For example, the (meth)acrylate-based monomer included in the styrene-based copolymer may include one or more selected from the group consisting of (meth)acrylate, methyl (meth)acrylate, ethyl (meth)acrylate, and propyl (meth)acrylate, preferably methyl (meth)acrylate. In this case, (meth)acrylate may include both of acrylate and methacrylate.

When the styrene-based copolymer is prepared using an alkyl styrene-based monomer, polymerization rate is slow, a long reaction time is required, the resulting copolymer has a low weight average molecular weight, and the resulting copolymer may be easily thermally decomposed. In addition, a copolymer having a high glass transition temperature may be prepared, but the copolymer has a remarkably high refractive index. Accordingly, in the present invention, the alkyl styrene-based monomer is not included.

For example, N-phenylmaleimide is preferably used as the maleimide-based monomer included in the styrene-based copolymer. When N-phenylmaleimide is used, compared to isopropyl maleimide, transparency, colorability, heat resistance, and reactivity may be improved.

The styrene-based copolymer may include the styrene monomer and the (meth) acrylate-based monomer in a weight ratio of <NUM>:<NUM> to <NUM>:<NUM> or <NUM>:<NUM> to <NUM>:<NUM>, preferably a weight ratio of <NUM>:<NUM> to <NUM>:<NUM> or <NUM>:<NUM> to <NUM>:<NUM>. Within this range, a styrene-based copolymer having a high glass transition temperature may be prepared. When such a styrene-based copolymer is applied to a thermoplastic resin composition, the heat resistance of the thermoplastic resin composition may be further improved.

For example, the styrene-based copolymer may be a low refractive index heat-resistant copolymer having a refractive index of <NUM> or less, preferably <NUM> to <NUM>, more preferably <NUM> to <NUM>.

In this description, refractive index may be measured at <NUM> using an Abbe refractometer according to a known method, e.g., ASTM D542.

In addition, the refractive index of the styrene-based copolymer may be measured using the refractive indexes and contents of each component (or polymer) constituting the styrene-based copolymer according to Equation <NUM> below:
<MAT>.

In Equation <NUM>, Wti represent the weight fraction (%) of each component (or polymer) of the styrene-based copolymer, and RIi represents the refractive index of a styrene-based copolymer-forming polymer.

As the glass transition temperature of the styrene-based copolymer is improved, a thermoplastic resin composition having excellent scratch resistance may be provided.

For example, the styrene-based copolymer may have a glass transition temperature of <NUM> or higher, preferably <NUM> to <NUM>, more preferably <NUM> to <NUM>.

In this description, glass transition temperature may be measured using a differential scanning calorimeter (product name: DSC Q20, manufacturer: Ta Instruments).

The styrene-based copolymer may have a weight average molecular weight of <NUM>,<NUM> to <NUM>,<NUM>/mol, preferably <NUM>,<NUM> to <NUM>,<NUM>/mol.

In this description, weight average molecular weight is measured at <NUM> using tetrahydrofuran (THF) as an eluate using a gel permeation chromatograph (GPC) filled with porous silica as a column packing material. In this case, weight average molecular weight is obtained as a relative value to a polystyrene standard (PS) specimen.

The styrene-based copolymer may have a residual oligomer content of <NUM> % by weight or less, preferably <NUM> to <NUM> % by weight.

In this description, residual oligomer content may be measured using a method commonly practiced in the art. For example, <NUM> of a sample is dissolved in <NUM> of chloroform, and polymers are precipitated using methanol to obtain the supernatant of the sample. Then, the supernatant is filtered using a <NUM> disc syringe filter, and residual oligomer content is measured using ALS-GC/FID.

As the residual oligomer content of a styrene-based copolymer decreases, a high-purity copolymer may be prepared.

In the present invention, when the styrene-based copolymer satisfies refractive index, glass transition temperature, weight average molecular weight, and residual oligomer content described above, a balance between colorability and heat resistance may be achieved. When such a copolymer is applied to a thermoplastic resin composition, the thermoplastic resin composition may have excellent colorability and heat deflection temperature.

In addition, as heat deflection temperature is improved, a thermoplastic resin composition having excellent scratch resistance may be prepared.

The styrene-based copolymer is preferably a methylmethacrylate-styrene-N-phenylmaleimide copolymer.

The styrene-based copolymer may be prepared by suspension-polymerizing the above described monomer mixture as described below. For reference, when the styrene-based copolymer is prepared by solution polymerization, the styrene-based copolymer may have a low product yield due to high viscosity, and the heat resistance of the styrene-based copolymer may be deteriorated due to low residual oligomer content.

For example, based on a total weight of the thermoplastic resin composition, the styrene-based copolymer may be included in an amount of <NUM> to <NUM> % by weight, preferably <NUM> to <NUM> % by weight, more preferably <NUM> to <NUM> % by weight. Within this range, weather resistance, colorability, processability, and scratch resistance may be improved while maintaining heat resistance.

The first graft copolymer may be prepared by graft-polymerizing acrylic-based rubber, an aromatic vinyl monomer, and a vinyl cyanide-based monomer. For example, the first graft copolymer may be a graft copolymer including an acrylic-based rubber polymer having an average particle diameter of <NUM> to <NUM>. In this case, in addition to mechanical properties such impact strength and tensile strength, heat resistance, colorability, and weather resistance may be excellent.

For example, the acrylic-based rubber included in the first graft copolymer may have an average particle diameter of <NUM> to <NUM>, preferably <NUM> to <NUM>, more preferably <NUM> to <NUM>. Within this range, mechanical properties, heat resistance, and weather resistance may be excellent. When the average particle diameter is less than the above range, mechanical properties, such impact strength and tensile strength, may be deteriorated. When the average particle diameter exceeds the above range, thermal stability may be reduced.

For example, based on a total weight of the first graft copolymer, the acrylic-based rubber included in the first graft copolymer may be included in an amount of <NUM> to <NUM> % by weight, preferably <NUM> to <NUM> % by weight, more preferably <NUM> to <NUM> % by weight. Within this range, weather resistance, impact strength, and scratch resistance may be excellent.

In this description, average particle diameter may be measured by dynamic light scattering, and specifically, may be measured as an intensity value using a Nicomp <NUM> particle size analyzer in a Gaussian mode.

For example, the acrylic-based rubber may be prepared by emersion-polymerizing the (meth)acrylate-based monomer. As a specific example, the acrylic-based rubber may be prepared by mixing the (meth)acrylate-based monomer, an emulsifier, an initiator, a grafting agent, a crosslinking agent, an electrolyte, and water and emulsion-polymerizing the mixture. In this case, grafting degree may be improved, and thus physical properties such as impact resistance may be excellent.

For example, the (meth)acrylate-based monomer may include one or more selected from the group consisting of alkyl (meth)acrylates having <NUM> to <NUM> carbon atoms, an alkyl acrylate containing an alkyl group having <NUM> to <NUM> carbon atoms, more preferably butyl acrylate or ethylhexyl acrylate.

The emulsion polymerization may be graft emulsion polymerization. For example, the emulsion polymerization may be performed at <NUM> to <NUM>, preferably <NUM> to <NUM>.

The emulsion polymerization may be performed in the presence of an initiator and an emulsifier.

The initiator is preferably a radical initiator. As a specific example, the initiator may include one or more selected from inorganic peroxides including sodium persulfate, potassium persulfate, ammonium persulfate, potassium superphosphate, and hydrogen peroxide; organic peroxides including t-butyl peroxide, cumene hydroperoxide, p-menthane hydroperoxide, di-t-butyl peroxide, t-butylcumyl peroxide, acetyl peroxide, isobutyl peroxide, octanoyl peroxide, dibenzoyl peroxide, <NUM>,<NUM>,<NUM>-trimethylhexanol peroxide, and t-butylperoxy isobutyrate; and azo compounds including azobis isobutyronitrile, azobis-<NUM>,<NUM>-dimethylvaleronitrile, azobis(cyclohexanecarbonylnitrile), and azobis isobutyric acid methyl.

In addition to the initiator, an activator may be further added to promote initiation reaction.

For example, the activator may include one or more selected from sodium formaldehyde sulfoxylate, sodium ethylenediamine tetraacetate, ferrous sulfate, dextrose, sodium pyrophosphate, anhydrous sodium pyrophosphate, and sodium sulfate.

For example, based on <NUM> parts by weight in total of rubber and monomers constituting the first graft copolymer, the initiator may be included in an amount of <NUM> to <NUM> part by weight, preferably <NUM> to <NUM> parts by weight, more preferably <NUM> to <NUM> parts by weight. Within this range, emulsion polymerization may be easily performed, and the residual amount of the initiator in the first graft copolymer may be minimized, as a specific example, the first graft copolymer may have a residual amount of the initiator of several tens of ppm.

For example, the emulsifier may include one or more selected from a potassium compound of alkylbenzene sulfonate, a sodium compound of alkylbenzene sulfonate, a potassium compound of alkyl carboxylate, a sodium compound of alkyl carboxylate, a potassium compound of oleic acid, a sodium compound of oleic acid, a potassium compound of alkyl sulfate, a sodium compound of alkyl sulfate, a potassium compound of alkyl dicarboxylate, a sodium compound of alkyl dicarboxylate, a potassium compound of alkyl ether sulfonate, a sodium compound of alkyl ether sulfonate, and an ammonium compound of allyloxynonylphenoxypropane-<NUM>-yloxy methylsulfonate, preferably sodium dodecylbenzenesulfonate.

A commercially available emulsifier may be used as the emulsifier. For example, one or more selected from SE10N, BC-<NUM>, BC-<NUM>, HS10, Hitenol KH10, and PD-<NUM> may be used as the emulsifier.

For example, based on <NUM> parts by weight in total of rubber and monomers constituting the first graft copolymer, the emulsifier may be included in an amount of <NUM> to <NUM> parts by weight, preferably <NUM> to <NUM> parts by weight, more preferably <NUM> to <NUM> parts by weight. Within this range, emulsion polymerization may be easily performed, and the residual amount of the initiator in the first graft copolymer may be minimized, as a specific example, the first graft copolymer may have a residual amount of the initiator of several tens of ppm.

When emulsion polymerization is performed, a molecular weight regulator may be further added. For example, the molecular weight regulator may include one or more selected from t-dodecyl mercaptan, N-dodecyl mercaptan, and alpha methyl styrene dimer, preferably t-dodecyl mercaptan.

For example, based on <NUM> parts by weight in total of rubber and monomers constituting the first graft copolymer, the molecular weight regulator may be included in an amount of <NUM> to <NUM> part by weight, preferably <NUM> to <NUM> parts by weight, more preferably <NUM> to <NUM> parts by weight.

The emulsion polymerization may be initiated after monomers and the like are fed into a reactor batchwise. Alternatively, a part of monomers and the like may be fed into a reactor before start of emulsion polymerization, and the remainder may be continuously fed after start of emulsion polymerization, or emulsion polymerization may be performed while monomers and the like are continuously fed for a predetermined time.

The first graft copolymer obtained in this way is formed in a latex form. Through coagulation, dehydration, and drying processes, the first graft copolymer may be obtained in a powder form.

As a coagulant used for the coagulation, a salt such as calcium chloride, magnesium sulfate, and aluminum sulfate, an acidic substance such as sulfuric acid, nitric acid, and hydrochloric acid, or a mixture thereof may be used.

For example, based on a total weight of the first graft copolymer, the aromatic vinyl-based monomer included in the first graft copolymer may be included in an amount of <NUM> to <NUM> % by weight, preferably <NUM> to <NUM> % by weight. Within this range, mechanical properties, such as tensile strength and impact strength, and processability may be excellent.

For example, the aromatic vinyl-based monomer may include one or more selected from the group consisting of styrene, α-methyl styrene, o-methyl styrene, ρ-methyl styrene, m-methyl styrene, ethyl styrene, isobutyl styrene, t-butyl styrene, o-bromo styrene, ρ-chloro styrene, m-bromo styrene, o-chlorostyrene, ρ-chloro styrene, m-chlorostyrene, vinyltoluene, vinylxylene, fluorostyrene, and vinylnaphthalene. In this case, processability may be excellent due to proper fluidity, and mechanical properties such as tensile strength and impact strength may be excellent.

For example, based on a total weight of the first graft copolymer, the vinyl cyanide-based monomer included in the first graft copolymer may be included in an amount of <NUM> to <NUM> % by weight, preferably <NUM> to <NUM> % by weight, more preferably <NUM> to <NUM> % by weight. Within this range, impact resistance and processability may be excellent.

For example, the vinyl cyanide-based monomer may be acrylonitrile, methacrylonitrile, or a mixture thereof. In this case, impact resistance and processability may be excellent.

Based on a total weight of the thermoplastic resin composition, the first graft copolymer may be included in an amount of <NUM> to <NUM> % by weight, preferably <NUM> to <NUM> % by weight, more preferably <NUM> to <NUM> % by weight. Within this range, in addition to mechanical properties such impact strength and tensile strength, heat resistance, weather resistance, scratch resistance, and colorability may be excellent. When the first graft copolymer is included in an amount less than the above range, impact resistance may be deteriorated. When the first graft copolymer is included in an amount exceeding the above range, fluidity and scratch resistance may be deteriorated.

The second graft copolymer may be prepared by graft-polymerizing acrylic-based rubber having an average particle diameter different from that of the acrylic-based rubber of the first graft copolymer, an aromatic vinyl monomer, and a vinyl cyanide-based monomer. For example, the second graft copolymer may be a graft copolymer including an acrylic-based rubber polymer having an average particle diameter of <NUM> to <NUM>. In this case, in addition to mechanical properties such impact strength and tensile strength, heat resistance, colorability, and weather resistance may be excellent.

For example, the acrylic-based rubber included in the second graft copolymer may have an average particle diameter of <NUM> to <NUM>, preferably <NUM> to <NUM>, more preferably <NUM> to <NUM>. Within this range, mechanical properties such as impact strength and tensile strength may be excellent. When the acrylic-based rubber has an average particle diameter less than the range, impact resistance may be deteriorated. When the acrylic-based rubber has an average particle diameter exceeding the range, fluidity and processability may be deteriorated.

For example, based on a total weight of the second graft copolymer, the acrylic-based rubber included in the second graft copolymer may be included in an amount of <NUM> to <NUM> % by weight, preferably <NUM> to <NUM> % by weight, more preferably <NUM> to <NUM> % by weight. Within this range, weather resistance, impact strength, and scratch resistance may be excellent.

For example, the acrylic-based rubber may be prepared by emulsion-polymerizing a (meth)acrylate-based monomer. As a specific example, the acrylic-based rubber may be prepared by mixing a (meth)acrylate-based monomer, an emulsifier, an initiator, a grafting agent, a crosslinking agent, an electrolyte, and water and emulsion-polymerizing the mixture. In this case, grafting degree may be improved, and thus physical properties such as impact resistance may be excellent.

The (meth)acrylate-based monomer, the emulsifier, the initiator, the grafting agent, and the like used to prepare the acrylic-based rubber may be the same as those used to prepare the acrylic-based rubber included in the first graft copolymer described above, and the contents thereof may be determined within the same content range as in the first graft copolymer.

The aromatic vinyl-based monomer and the vinyl cyanide-based monomer may be the same as those included in the first graft copolymer described above.

For example, based on a total weight of the second graft copolymer, the aromatic vinyl-based monomer included in the second graft copolymer may be included in an amount of <NUM> to <NUM> % by weight, preferably <NUM> to <NUM> % by weight. Within this range, impact resistance, weather resistance, and chemical resistance may be excellent.

For example, based on a total weight of the second graft copolymer, the vinyl cyanide-based monomer included in the second graft copolymer may be included in an amount of <NUM> to <NUM> % by weight, preferably <NUM> to <NUM> % by weight, more preferably <NUM> to <NUM> % by weight. Within this range, impact resistance and processability may be excellent.

In this description, the term "total weight of a copolymer" may mean the actual total weight of the obtained copolymer or may mean the total weight of rubber and/or monomers added instead of the copolymer.

Based on a total weight of the thermoplastic resin composition, the second graft copolymer may be included in an amount of <NUM> to <NUM> % by weight, preferably <NUM> to <NUM> % by weight, more preferably <NUM> to <NUM> % by weight. Within this range, in addition to mechanical properties such impact strength and tensile strength, heat resistance, weather resistance, scratch resistance, and colorability may be excellent. When the second graft copolymer is included in an amount less than the range, impact resistance may be deteriorated. When the second graft copolymer is included in an amount exceeding the range, grafting degree may be reduced, resulting in deterioration in hardness and scratch resistance.

For example, the thermoplastic resin composition may include one or more selected from the group consisting of a lubricant, an antioxidant, a UV stabilizer, a release agent, a pigment, and a dye. In this case, weather resistance, heat resistance, processability, and scratch resistance may be excellent without deterioration in mechanical properties.

For example, the lubricant may include one or more selected from the group consisting of ethylenebis stearamide, oxidized polyethylene wax, and magnesium stearate, preferably ethylene bis stearamide. When the lubricant is ethylene bis stearamide, the wettability of the composition of the present invention may be improved, and the mechanical properties thereof may be excellent.

For example, based on <NUM> parts by weight in total of the styrene-based copolymer, the first graft copolymer, and the second graft copolymer, the lubricant may be included in an amount of <NUM> to <NUM> parts by weight, preferably <NUM> to <NUM> parts by weight, more preferably <NUM> to <NUM> parts by weight. Within this range, the wettability of the composition of the present invention may be improved, and the mechanical properties thereof may be excellent.

For example, the antioxidant may include phenolic antioxidants, phosphorus antioxidants, or mixtures thereof. In this case, oxidation by heat may be prevented during an extrusion process, and the mechanical properties of the composition of the present invention may be excellent.

For example, based on <NUM> parts by weight in total of the styrene-based copolymer, the first graft copolymer, and the second graft copolymer, the antioxidant may be included in an amount of <NUM> to <NUM> parts by weight, preferably <NUM> to <NUM> part by weight, more preferably <NUM> to <NUM> part by weight. Within this range, oxidation by heat may be prevented during an extrusion process, and the mechanical properties of the composition of the present invention may be excellent.

For example, based on <NUM> parts by weight in total of the styrene-based copolymer, the first graft copolymer, and the second graft copolymer, the dye may be included in an amount of <NUM> to <NUM> parts by weight, preferably <NUM> to <NUM> part by weight. Within this range, color expression may be excellent without deterioration in the intrinsic physical properties of the composition of the present invention.

For example, the thermoplastic resin composition may have a weather resistance (ΔE) of <NUM> or less, preferably <NUM> to <NUM>, more preferably <NUM> to <NUM>. Within this range, physical property balance may be excellent.

In this description, weather resistance (ΔE) may be measured using a weather resistance tester (QUV) under measurement conditions of UV LAMP Illuminance: <NUM> W/m<NUM>, humidity: <NUM> %, BLACK PANEL temperature: <NUM>, and residence time: <NUM> hours. ΔE is the arithmetic mean value of Hunter Lab values before and after residence calculated by Equation <NUM> below. Weather resistance increases as the value of ΔE approaches zero.

For example, the thermoplastic resin composition may have an L value (colorability) of <NUM> or less, preferably <NUM> to <NUM>, more preferably <NUM> to <NUM> as measured using a Hunter Lab. Within this range, physical property balance may be excellent.

For example, the thermoplastic resin composition may have a fluidity of <NUM> to <NUM>/<NUM>, preferably <NUM> to <NUM>/<NUM> as measured at <NUM> under a load of <NUM> according to ASTM D1238. Within this range, processability may be excellent.

For example, the thermoplastic resin composition may have a pencil hardness of <NUM> or more, preferably <NUM> to <NUM> as measured at <NUM> ° under a load of <NUM> using a pencil hardness tester (Cometech) according to ASTM D3363. Within this range, physical property balance and scratch resistance may be excellent.

For example, the thermoplastic resin composition may have a heat deflection temperature of <NUM> or higher, preferably <NUM> to <NUM>, more preferably <NUM> to <NUM> as measured according to ASTM D648. Within this range, physical property balance may be excellent.

For example, the thermoplastic resin composition may have an Izod impact strength (<NUM>/<NUM>", <NUM>) of <NUM> kgf·cm/cm or more, preferably <NUM> to <NUM> kgf·cm/cm, more preferably <NUM> to <NUM> kgf·cm/cm as measured according to ASTM D256. Within this range, the balance of all physical properties may be excellent.

In description of a method of preparing the thermoplastic resin composition of the present invention, all of the contents of the above-described thermoplastic resin composition are included.

For example, the method of preparing the thermoplastic resin composition is as follows.

For example, the method of preparing the thermoplastic resin composition may include a step of preparing a styrene-based copolymer by suspension-polymerizing a polymerization solution prepared by mixing <NUM> parts by weight of a monomer mixture including a (meth)acrylate-based monomer, a styrene monomer, and a maleimide-based monomer, <NUM> to <NUM> parts by weight of a reaction solvent, <NUM> to <NUM> part by weight of an initiator, <NUM> to <NUM> parts by weight of a dispersant, and <NUM> to <NUM> part by weight of a molecular weight regulator.

In the step of preparing a styrene-based copolymer, a reaction solvent may be water. In this case, reaction heat may be easily controlled, and polymerization may be performed even at high viscosity, which increases polymerization conversion rate.

For example, based on <NUM> parts by weight of the monomer mixture, the reaction solvent may be included in an amount of <NUM> to <NUM> parts by weight, preferably <NUM> to <NUM> parts by weight. Within this range, monomers may be easily mixed, and polymerization stability may be improved, so that a uniform composition and high polymerization conversion may be obtained.

In the step of preparing a styrene-based copolymer, for example, the initiator is a peroxide, and preferably includes one or more selected from the group consisting of t-butylperoxy-<NUM>-ethylhexanoate, benzoyl peroxide, t-butyl peroxyisobutyrate, <NUM>,<NUM>-bis(t-butylperoxy)cyclohexane, <NUM>,<NUM>-bis(<NUM>,<NUM>-di-t-butylperoxycyclohexane)propane, t-hexylperoxyisopropyl monocarbonate, t-butyl peroxylaurate, t-butylperoxy isopropyl monocarbonate, t-butylperoxy <NUM>-ethylhexyl monocarbonate, t-hexyl peroxybenzoate, t-butyl peroxyacetate, <NUM>,<NUM>-bis(t-butylperoxy)butane, t-butyl peroxybenzoate, dicumyl peroxide, <NUM>,<NUM>-dimethyl-<NUM>,<NUM>-bis(t-butylperoxy)hexane, t-butylcumyl peroxide, di-t-butyl peroxide, and di-t-amine peroxide.

In this case, polymerization may be easily performed, and thus mechanical properties, weather resistance, heat resistance, and scratch resistance may excellent.

For example, based on <NUM> parts by weight of the monomer mixture, the initiator may be included in an amount of <NUM> to <NUM> part by weight, preferably <NUM> to <NUM> parts by weight, more preferably <NUM> to <NUM> parts by weight. Within this range, polymerization may be easily performed, and thus mechanical properties, weather resistance, heat resistance, and scratch resistance may excellent.

In the step of preparing a styrene-based copolymer, for example, the dispersant may be a phosphate salt, preferably a metal phosphate salt, more preferably tricalcium phosphate. In this case, polymerization stability may be improved, and thus a copolymer having a high polymerization conversion rate may be prepared.

For example, based on <NUM> parts by weight of the monomer mixture, the dispersant may be included in an amount of <NUM> to <NUM> parts by weight, preferably <NUM> to <NUM> parts by weight. Within this range, polymerization may be easily performed, and uniform particles may be prepared, allowing easy processing.

In the step of preparing a styrene-based copolymer, for example, suspension polymerization may be performed by stirring the polymerization solution at <NUM> to <NUM> and a stirring rate of <NUM> to <NUM> rpm for <NUM> to <NUM> hours. In this case, the polymerization conversion rate of a copolymer may be improved, and the contents of residual monomers and residual oligomers in particles may be reduced, thereby improving mechanical properties, weather resistance, heat resistance, scratch resistance, and colorability.

As a specific example, in terms of the conversion rate, colorability, and residual oligomer content of the styrene-based copolymer, most preferably, polymerization is performed at <NUM> to <NUM> for <NUM> to <NUM> hours, and then polymerization is performed at <NUM> to <NUM> for <NUM> to <NUM> hours. When polymerization time exceeds the range and polymerization is performed for a long time, conversion rate is insignificantly affected, and colorability and residual oligomer content may be increased. When polymerization time is less than the range and polymerization is performed for a short time, conversion rate may be reduced, and colorability and residual oligomer content may be increased.

Then, the pH of a polymerization slurry formed by the suspension polymerization may be adjusted to <NUM> to <NUM> to prepare a styrene-based copolymer in a bead form. When the above-described pH range is satisfied, the dispersant contained in the reactant may be effectively removed, and a product of high purity may be manufactured.

In this description, methods commonly used in the art may be used to measure pH. For example, pH may be measured using a pH meter.

In this case, the pH of the polymerization slurry may be adjusted using an acid solution, for example, formic acid or hydrochloric acid.

For example, the kneading and extrusion may be performed using a single-screw extruder, a twin-screw extruder, or a Banbury mixer. In this case, a composition may be uniformly dispersed, and thus compatibility may be excellent.

For example, the kneading and extrusion may be performed at a barrel temperature of <NUM> to <NUM>, preferably <NUM> to <NUM>. In this case, throughput per unit time may be appropriate, and melt-kneading may be sufficiently performed. In addition, thermal decomposition of a resin component may be prevented.

For example, the kneading and extrusion may be performed at a screw rotation rate of <NUM> to <NUM> rpm, preferably <NUM> to <NUM> rpm. In this case, since throughput per unit time is appropriate, process efficiency may be excellent, and excessive cutting may be prevented.

For example, the molded article of the present invention may be manufactured using the thermoplastic resin composition of the present invention. In this case, weather resistance, colorability, processability, and scratch resistance may be improved while maintaining heat resistance.

For example, the molded article may include one or more selected from the group consisting of automobile parts, electrical and electronic parts, and building materials.

In describing the thermoplastic resin composition of the present invention, the method of preparing the same, and the molded article including the same, other conditions or equipment not explicitly described can be appropriately selected within the range commonly practiced in the art, without particular limitation.

Hereinafter, exemplary embodiments of the present invention will be described in detail so as for those of ordinary skill in the art to easily implement the present invention. The present invention may be implemented in various different forms and is not limited to these embodiments.

Materials used in Examples and Comparative Examples below are as follows.

<NUM> parts by weight of deionized water, <NUM> parts by weight of methylmethacrylate (hereinafter referred to as "MMA"), <NUM> parts by weight of N-phenylmaleimide (hereinafter referred to as "PMI"), <NUM> parts by weight of styrene (hereinafter referred to as "SM"), <NUM> parts by weight of t-butylperoxybenzoate as an initiator, <NUM> parts by weight of tricalcium phosphate as a dispersant, and <NUM> parts by weight of t-dodecyl mercaptan as a molecular weight regulator were introduced into a reactor, and then polymerization was initiated by raising temperature to <NUM> at <NUM> rpm. The polymerization reaction was maintained for <NUM> hours. Thereafter, the polymerization reaction was completed.

Formic acid was added to the prepared polymerization slurry to adjust the pH thereof to <NUM> to remove the dispersant, and then washing, dehydration, and drying were performed to prepare a styrene-based copolymer in a bead form. The prepared copolymer had a refractive index of <NUM>, a glass transition temperature of <NUM>, and a weight average molecular weight of <NUM>,<NUM>/mol.

<NUM> part by weight of a lubricant, <NUM> parts by weight of an antioxidant, and <NUM> parts by weight of a dye were added to <NUM> parts by weight of a copolymer composition consisting of <NUM> parts by weight of the prepared styrene-based copolymer (A), <NUM> parts by weight of the first graft copolymer (B), and <NUM> parts by weight of the second graft copolymer (C), and the mixture was introduced into an extruder (28Φ) at <NUM> to prepare a resin in a pellet form. Then, the resin was injected to obtain a specimen.

Specimens were prepared in the same manner as in Example <NUM>, except that the components and the contents shown in Table <NUM> below were used when preparing the styrene-based copolymer (A).

Specimens were prepared in the same manner as in Example <NUM>, except that the components and the contents shown in Table <NUM> below were used when preparing the styrene-based copolymer (A). For reference, in Comparative Example <NUM>, α-methyl styrene (hereinafter referred to as "AMS") was added instead of SM.

A specimen was prepared in the same manner as in Example <NUM>, except that the process of preparing the styrene-based copolymer (A) described above was replaced with a process described below.

Specifically, a polymerization solution prepared by adding <NUM> parts by weight of dicumyl peroxide to <NUM> parts by weight of a monomer solution consisting of <NUM> % by weight of toluene, <NUM> % by weight of methylmethacrylate, <NUM> % by weight of N-phenylmaleimide, and <NUM> % by weight of styrene was fed into a <NUM> continuous reactor at a rate of <NUM>/hr to perform polymerization. Then, the resultant was immersed in a volatile tank at <NUM> to remove unreacted monomers and the reaction solvent to prepare a heat-resistant copolymer in a pellet form.

A polymer in a pellet form was prepared in the same manner as in Example <NUM>, except that the styrene-based copolymer (A) of Example <NUM> was replaced with a styrene-based copolymer (A-<NUM>) including <NUM> parts by weight of methylmethacrylate (hereinafter referred to as "MMA"), <NUM> parts by weight of acrylonitrile (hereinafter referred to as "AN"), and <NUM> parts by weight of styrene, and the first graft copolymer (B) and the second graft copolymer (C) were added according to the content ranges shown in Table <NUM> below.

The physical properties of the specimens prepared in Examples <NUM> to <NUM> and Comparative Examples <NUM> to <NUM> were measured according to the following methods, and the results are shown in Tables <NUM> and <NUM> below.

(In Table <NUM>, A indicates the styrene-based copolymer).

As shown in Tables <NUM> and <NUM>, compared to Comparative Examples <NUM> to <NUM> outside the range of the present invention, in the case of Examples <NUM> to <NUM> according to the present invention, in addition to impact strength, heat resistance, and weather resistance, fluidity, heat deflection temperature, pencil hardness (scratch resistance), and colorability are excellent.

In addition, as shown in Table <NUM>, the styrene-based copolymers (A) prepared in Examples <NUM> to <NUM> according to the present invention have a low refractive index and a high glass transition temperature, indicating that the colorability and heat deflection temperature of a resin composition are improved.

On the other hand, as shown in Table <NUM>, in the case of Comparative Examples <NUM> to <NUM>, in all cases, residual oligomer contents are <NUM> % by weight or more.

In addition, in the case of Comparative Examples <NUM> and <NUM> not satisfying the weight ratio of SM/MMA of <NUM>:<NUM> to <NUM>:<NUM> or <NUM>:<NUM> to <NUM>:<NUM> in the styrene-based copolymer (A), pencil hardness (scratch resistance) is poor. In particular, in the case of Comparative Example <NUM> having a lower MMA content than Comparative Example <NUM>, all of fluidity, heat deflection temperature, and colorability are poor.

In addition, in the case of Comparative Example <NUM> having a weight ratio of SM/MMA of less than <NUM>:<NUM> and Comparative Example <NUM> having a weight ratio of SM/MMA of exceeding <NUM>:<NUM>, the weight average molecular weight of the styrene-based copolymer is poor, thereby deteriorating pencil hardness (scratch resistance).

In addition, in the case of Comparative Example <NUM> having significantly less PMI content compared to SM, Tg and heat deflection temperature are low, and pencil hardness (scratch resistance) is poor.

In addition, in the case of Comparative Example <NUM> using an alkyl-substituted aromatic vinyl-based compound instead of styrene, polymerization conversion rate is reduced, residual oligomer content is increased, and colorability is deteriorated due to increase in refractive index.

In addition, in the case of Comparative Example <NUM> using bulk polymerization, the weight average molecular weight of the styrene-based copolymer is poor, thereby reducing pencil hardness (scratch resistance) or increasing residual oligomer content.

In addition, in the case of Comparative Example <NUM> using a transparent styrene-based copolymer not including a heat resistance monomer, although the content of transparent residual oligomers is within an appropriate range, heat resistance is greatly reduced, and pencil hardness (scratch resistance) and colorability are significantly deteriorated.

Claim 1:
A thermoplastic resin composition, comprising:
a styrene-based copolymer comprising a (meth)acrylate-based monomer, a styrene monomer, and a maleimide-based monomer;
a first graft copolymer comprising an acrylic-based rubber polymer, an aromatic vinyl-based monomer, and a vinyl cyanide-based monomer; and
a second graft copolymer comprising an acrylic-based rubber polymer, an aromatic vinyl-based monomer, and a vinyl cyanide-based monomer,
wherein the styrene-based copolymer has a residual oligomer content of <NUM> % by weight or less, measured by the method disclosed in the description, and
the acrylic-based rubber polymer of the first graft copolymer and the acrylic-based rubber polymer of the second graft copolymer have different average particle diameters.