Method for preparing graft copolymer, graft copolymer, and resin composition comprising the same

Abstract

The present invention provides a method for preparing a graft copolymer used in a resin composition comprising the graft copolymer and a base resin, and relates to a method for preparing a graft copolymer, a graft copolymer prepared by the method, and a resin composition comprising the graft copolymer, which maintains impact properties such as impact strength and falling ball impact strength to the same or better level, while improving flowability and subsequently improving processability.

Description

Technical Field

[0001] [Cross-references to related applications]

[0002] This application claims the benefit of priority based on Korean Patent Application No. 10-2021-0104040, filed on August 6, 2021, the entire contents of which are incorporated herein by reference.

[0003] The present invention relates to a method for preparing a graft copolymer, a graft copolymer, and a resin composition comprising the graft copolymer. Background Technology

[0004] Acrylonitrile-butadiene-styrene (ABS) copolymers are prepared by graft copolymerization of styrene and acrylonitrile onto butadiene rubber polymers. Compared to conventional high-impact polystyrene (HIPS), ABS copolymers exhibit superior impact resistance, chemical resistance, thermal stability, colorability, fatigue resistance, rigidity, and processability, and are used in applications such as interior and exterior materials for automobiles, office equipment, and components for various electrical and electronic products or toys.

[0005] ABS copolymers are typically prepared via emulsion polymerization and, depending on the properties of the mixed matrix resin, are used in conventional resin compositions, flame-retardant resin compositions, extruded resin compositions, heat-resistant resin compositions, and transparent resin compositions. Thus, because ABS copolymers can be used in a wide variety of fields, efforts are continuously being made to ensure that ABS copolymers meet the physical properties required in these diverse applications, in addition to the matrix resin.

[0006] Meanwhile, ABS copolymers are generally impact-resistant. Therefore, as a method to improve the impact resistance of ABS copolymers, a method has been proposed to control the monomer ratio and maximize the grafting rate to change the composition of monomers to be grafted into and outside the rubber particles. However, in this case, the deterioration of flowability may cause the problem of deterioration of processing performance during the preparation of resin compositions containing ABS copolymers and matrix resins.

[0007] In addition, even if the same ABS copolymer is used in a resin composition containing ABS copolymer and matrix resin, the physical properties of the ABS copolymer itself may not be fully manifested depending on the type of matrix resin, and defects may occur that individually degrade physical properties such as impact resistance and processability.

[0008] [Existing technical documents]

[0009] [Patent Literature]

[0010] (Patent Document 1) JP1994-92346A Summary of the Invention

[0011] Technical issues

[0012] In order to solve the problems mentioned in the background art, the object of the present invention is to prepare a graft copolymer in a resin composition comprising the graft copolymer and a matrix resin, wherein the graft copolymer is capable of maintaining the same or better impact properties regardless of the type of matrix resin, and is capable of improving flowability and processability.

[0013] That is, the present invention is designed to solve the problems of conventional technology, and one object is to provide a method for preparing a graft copolymer, which is applied to a resin composition comprising the graft copolymer and a matrix resin, wherein impact properties such as impact strength and falling ball impact strength are maintained at the same or better level, and flowability and thus processability are improved.

[0014] Another object of the present invention is to provide a graft copolymer prepared by the preparation method described above.

[0015] Another object of the present invention is to provide a resin composition comprising the graft copolymer.

[0016] Technical solution

[0017] To address the aforementioned issues, the present invention provides a method for preparing a graft copolymer, the graft copolymer thus prepared, and a resin composition comprising the graft copolymer.

[0018] (1) The present invention provides a method for preparing a graft copolymer, comprising: a step (S10) of batch injecting a first monomer mixture and a first molecular weight regulator and polymerizing them in the presence of a conjugated diene polymer latex to prepare a preliminary graft copolymer latex containing a preliminary graft copolymer; and a step (S20) of continuously injecting a second monomer mixture, a first molecular weight regulator and a second molecular weight regulator different from the first molecular weight regulator, and polymerizing them in the presence of the preliminary graft copolymer latex prepared in step (S10) to prepare a graft copolymer latex containing a graft copolymer, wherein the first monomer mixture comprises 60% to 85% by weight of aromatic vinyl monomers and 15% to 40% by weight of vinyl cyanide monomers, and the second monomer mixture comprises 73% to 99% by weight of aromatic vinyl monomers and 1% to 27% by weight of vinyl cyanide monomers.

[0019] (2) The present invention provides a method for preparing graft copolymers according to (1), wherein the conjugated diene polymer latex comprises a conjugated diene polymer, and the conjugated diene polymer is injected at 50 to 80 parts by weight based on a total injection amount of 100 parts by weight of the conjugated diene polymer, aromatic vinyl monomers and vinyl cyanide monomers.

[0020] (3) The present invention provides a method for preparing graft copolymers according to (1) or (2), wherein the first monomer mixture comprises 25% to 40% by weight of vinyl cyanide monomers.

[0021] (4) The present invention provides a method for preparing a graft copolymer according to any one of (1) to (3), wherein the second monomer mixture comprises 15% to 25% by weight of a vinyl cyanide monomer.

[0022] (5) The present invention provides a method for preparing a graft copolymer according to any one of (1) to (4), wherein the first molecular weight regulator is one or more selected from tert-dodecyl mercaptan, n-dodecyl mercaptan, octyl mercaptan, carbon tetrachloride, dichloromethane, dibromomethane, tetraethylthiuram disulfide, dipentylthiuram disulfide and diisopropyl xanthate disulfide.

[0023] (6) The present invention provides a method for preparing a graft copolymer according to any one of (1) to (5), wherein, based on the total amount of 100 parts by weight of the conjugated diene polymer, the aromatic vinyl monomer and the vinyl cyanide monomer, the total amount of the first molecular weight regulator in steps (S10) and (S20) is 0.20 parts by weight to 0.40 parts by weight.

[0024] (7) The present invention provides a method for preparing a graft copolymer according to any one of (1) to (7), wherein the second molecular weight regulator is one or more selected from α-methylstyrene dimer, n-dodecyl mercaptan, octyl mercaptan, carbon tetrachloride, dichloromethane, dibromomethane, tetraethylthiuram disulfide, diamethylene thiuram disulfide and diisopropyl xanthate disulfide.

[0025] (8) The present invention provides a method for preparing a graft copolymer according to any one of (1) to (8), wherein, based on the total amount of 100 parts by weight of conjugated diene polymer, aromatic vinyl monomer and vinyl cyanide monomer, the amount of the second molecular weight regulator injected in step (S20) is 0.01 parts by weight to 0.40 parts by weight.

[0026] (9) The present invention provides a graft copolymer prepared according to any one of (1) to (8) by a method for preparing a graft copolymer, comprising: a conjugated diene polymer; a first graft layer formed by permeation into or outside the conjugated diene polymer; and a second graft layer formed by encapsulating the first graft layer, wherein the first graft layer comprises 60% to 85% by weight of aromatic vinyl monomer units and 15% to 40% by weight of vinyl cyanide monomer units, and the second graft layer comprises 73% to 99% by weight of aromatic vinyl monomer units and 1% to 27% by weight of vinyl cyanide monomer units.

[0027] (10) The present invention provides a resin composition comprising the graft copolymer according to (9) and a matrix resin.

[0028] (11) The present invention provides a resin composition according to (10), wherein the matrix resin comprises aromatic vinyl monomer units and vinyl cyanide monomer units.

[0029] (12) The present invention provides a resin composition according to (10) or (11), wherein the matrix resin comprises α-methylstyrene monomer units and vinyl cyanide monomer units.

[0030] Beneficial effects

[0031] In a resin composition comprising a graft copolymer and a matrix resin, the graft copolymer prepared by the method for preparing the graft copolymer according to the present invention can maintain the same or better impact properties regardless of the type of matrix resin, and can improve flowability and subsequently improve processing properties. Detailed Implementation

[0032] The invention will now be described in more detail to aid in understanding it.

[0033] It should be understood that the words or terms used in the specification and claims of this invention should not be construed as having the meanings defined in common dictionaries. It should be understood that, based on the inventor's ability to appropriately define the meanings of words to better illustrate the principles of the invention, the words or terms should be understood to have meanings consistent with their meanings in the technical concept of this invention.

[0034] The term "monomer unit" in this invention can refer to a component or structure derived from a monomer or the material itself. In specific embodiments, it can refer to a repeating unit formed in a polymer during the polymerization process by the participation of a monomer injected into the polymerization reaction.

[0035] The term "latex" in this invention can refer to a dispersed polymer or copolymer polymerized in water, and in particular, can refer to dispersed microparticles of a polymer or copolymer having a rubber phase polymerized in water in a colloidal state by emulsion polymerization.

[0036] The term "composition" as used in this invention includes reaction products and decomposition products formed from materials of the corresponding composition, as well as mixtures of materials containing the corresponding composition.

[0037] This invention provides a method for preparing graft copolymers.

[0038] According to one embodiment of the present invention, the method for preparing the graft copolymer includes: step (S10) of batch injection of a first monomer mixture and a first molecular weight regulator, and polymerization in the presence of a conjugated diene polymer latex to prepare a preliminary graft copolymer latex containing a preliminary graft copolymer; and step (S20) of continuously injection of a second monomer mixture, a first molecular weight regulator and a second molecular weight regulator different from the first molecular weight regulator, and polymerization in the presence of the preliminary graft copolymer latex prepared in step (S10) to prepare a graft copolymer latex containing a graft copolymer, wherein the first monomer mixture may contain 60% to 85% by weight of aromatic vinyl monomers and 15% to 40% by weight of vinyl cyanide monomers, and the second monomer mixture may contain 73% to 99% by weight of aromatic vinyl monomers and 1% to 27% by weight of vinyl cyanide monomers.

[0039] According to one embodiment of the present invention, the method for preparing the graft copolymer can be carried out by step (S10) pre-grafting a first monomer mixture onto a conjugated diene polymer, forming a first graft layer by permeating monomer units formed from the first monomer mixture into or forming them on the outside of the conjugated diene polymer, and forming a second graft layer in the encapsulation shape of the first graft layer by step (S20), thereby preparing a core-shell graft copolymer.

[0040] According to one embodiment of the present invention, steps (S10) and (S20) can be carried out continuously in the graft copolymerization for preparing the graft copolymer. Specifically, this can be carried out by continuously injecting a second monomer mixture, a first molecular weight regulator, and a second molecular weight regulator different from the first molecular weight regulator during the batch injection and polymerization of the first monomer mixture and the first molecular weight regulator in the presence of a conjugated diene polymer latex according to step (S10).

[0041] According to one embodiment of the invention, step (S10) can be carried out in the presence of a conjugated diene polymer latex. Therefore, the first monomer mixture injected in step (S10) can be grafted onto the conjugated diene polymer contained in the conjugated diene polymer latex to prepare a preliminary graft copolymer comprising a first graft layer formed by monomer units formed from the first monomer mixture permeating into or outside the conjugated diene polymer. The conjugated diene polymer latex can be prepared by step (S1) for preparing the conjugated diene polymer. Step (S1) is the step of polymerizing conjugated diene monomers to prepare the conjugated diene polymer, and the conjugated diene monomers can be one or more selected from 1,3-butadiene, 2,3-dimethyl-1,3-butadiene, isoprene, 3-butyl-1,3-octadiene, isoprene, and 2-phenyl-1,3-butadiene, specifically 1,3-butadiene.

[0042] According to one embodiment of the present invention, step (S1) can be carried out by emulsion polymerization, thus obtaining a conjugated diene polymer latex type containing conjugated diene polymers.

[0043] According to one embodiment of the present invention, step (S1) can be carried out via free radical polymerization using a peroxide initiator, a redox initiator, or an azo initiator, and the redox initiator can be, for example, one or more selected from tert-butyl hydroperoxide, diisopropylbenzene hydroperoxide, and isopropylbenzene hydroperoxide. In this case, a stable polymerization environment can be provided.

[0044] According to one embodiment of the invention, if a redox initiator is used, it may also include ferrous sulfate, sodium ethylenediaminetetraacetate, or sodium formaldehyde sulfoxylate.

[0045] According to one embodiment of the present invention, the emulsifier used in the emulsion polymerization process in step (S1) can be one or more selected from anionic emulsifiers, cationic emulsifiers, and nonionic emulsifiers, specifically, one or more selected from alkyl aryl sulfonates, basic methyl alkyl sulfates, fatty acid soaps, basic oleates, basic rosin salts, basic laurates, sodium diethylhexyl phosphate, phosphonated polyoxyethylene alcohol, and phosphonated polyoxyethylene phenol. In this case, it can have the effect of providing a stable polymerization environment. Based on the total amount of 100 parts by weight of the conjugated diene monomer injected in step (S1), the emulsifier can be injected in, for example, less than 5.0 parts by weight, less than 3.0 parts by weight, or 0.5 parts by weight to 2.5 parts by weight.

[0046] According to one embodiment of the present invention, the emulsion polymerization in step (S1) can be carried out in an aqueous solvent, and the aqueous solvent can be ion-exchanged water.

[0047] According to one embodiment of the invention, the conjugated diene polymer latex may comprise a conjugated diene polymer, and based on the total injection amount of 100 parts by weight of the conjugated diene polymer, aromatic vinyl monomers, and vinyl cyanide monomers, the conjugated diene polymer may be injected at an amount of 50 to 80 parts by weight. Here, the injection amount of the conjugated diene polymer refers to the basic amount of the solids content of the conjugated diene polymer in the conjugated diene polymer latex. In one specific embodiment, based on the total injection amount of 100 parts by weight of the conjugated diene polymer, aromatic vinyl monomer, and vinyl cyanide monomer, the conjugated diene polymer can be more than 50 parts by weight, more than 52 parts by weight, more than 54 parts by weight, more than 56 parts by weight, more than 58 parts by weight, or more than 60 parts by weight, and less than 80 parts by weight, less than 75 parts by weight, less than 70 parts by weight, less than 68 parts by weight, less than 66 parts by weight, less than 64 parts by weight, less than 62 parts by weight, or less than 60 parts by weight. Within this range, the compatibility degradation of the graft copolymer with the matrix resin can be prevented, and the impact resistance can be improved.

[0048] According to one embodiment of the invention, the first monomer mixture injected in step (S10) may comprise aromatic vinyl monomers and vinyl cyanide monomers. In this case, during the preparation of the resin composition comprising the graft copolymer, it is important to control the amount of vinyl cyanide monomers in the first monomer mixture in order to improve flowability and subsequently improve processing properties, while maintaining the same or better levels of impact properties such as impact resistance regardless of the type of matrix resin. In a specific embodiment, the first monomer mixture may comprise 15% by weight or more, 16% by weight or more, 17% by weight or more, 18% by weight or more, 19% by weight or more, 20% by weight or more, 21% by weight or more, 22% by weight or more, 23% by weight or more, 24% by weight or more, or 25% by weight or more, and less than 40% by weight, less than 39% by weight, less than 38% by weight, less than 37% by weight, less than 36% by weight, less than 35% by weight, less than 34% by weight, less than 33% by weight, less than 32% by weight, less than 31% by weight, or less than 30% by weight of vinyl cyanide monomers. Within this range, during the polymerization of graft copolymers, significant increases in the middle and end of polymerization, as well as deviations from the controlled temperature range during polymerization, can be prevented. This ensures sufficient impact strength and flowability for general-purpose matrix resins such as styrene-acrylonitrile copolymers, and prevents degradation of impact strength for heat-resistant matrix resins such as α-methylstyrene-acrylonitrile copolymers.

[0049] According to one embodiment of the invention, depending on the amount of vinyl cyanide monomers, the first monomer mixture may contain 60% by weight or more, 61% by weight or more, 62% by weight or more, 63% by weight or more, 64% by weight or more, 65% by weight or more, 66% by weight or more, 67% by weight or more, 68% by weight or more, 69% by weight or more, or 70% by weight or more, and less than 85% by weight, less than 84% by weight, less than 83% by weight, less than 82% by weight, less than 81% by weight, less than 80% by weight, less than 79% by weight, less than 78% by weight, less than 77% by weight, less than 76% by weight, or less than 75% by weight of aromatic vinyl monomers. In addition to aromatic vinyl monomers and vinyl cyanide monomers, the first monomer mixture may, as needed, also contain vinyl monomers that can be copolymerized with conjugated diene polymers, aromatic vinyl monomers, and vinyl cyanide monomers.

[0050] According to one embodiment of the invention, based on the total injection amount of the conjugated diene polymer, aromatic vinyl monomer, and vinyl cyanide monomer injected during the preparation of the graft copolymer (100 parts by weight), the first monomer mixture can be injected in amounts from 5 to 20 parts by weight. In a specific embodiment, based on the total injection amount of the conjugated diene polymer, aromatic vinyl monomer, and vinyl cyanide monomer (100 parts by weight), the first monomer mixture can be 5 or more parts by weight, 6 or more parts by weight, 7 or more parts by weight, 8 or more parts by weight, 9 or more parts by weight, or 10 or more parts by weight, and less than 20 parts by weight, less than 19 parts by weight, less than 18 parts by weight, less than 17 parts by weight, less than 16 parts by weight, or 15 parts by weight. Within this range, compatibility degradation between the graft copolymer and the matrix resin can be prevented, and impact resistance can be improved.

[0051] According to one embodiment of the invention, the second monomer mixture injected in step (S20) may contain aromatic vinyl monomers and vinyl cyanide monomers. In this case, the aromatic vinyl monomers of the first monomer mixture and the aromatic vinyl monomers of the second monomer mixture may be the same as or different from each other. Additionally, the vinyl cyanide monomers of the first monomer mixture and the vinyl cyanide monomers of the second monomer mixture may be the same as or different from each other. Meanwhile, in the preparation of the resin composition containing the graft copolymer, in order to improve flowability and subsequently improve processing properties, while maintaining impact properties such as impact resistance regardless of the type of matrix resin, it is important to control the vinyl cyanide monomer content in the second monomer mixture, in addition to controlling the vinyl cyanide monomer content in the first monomer mixture. If the vinyl cyanide monomer content in the first and second monomer mixtures is not properly controlled in this way, although impact strength for general-purpose matrix resins such as styrene-acrylonitrile copolymers can be ensured, impact strength for heat-resistant matrix resins such as α-methylstyrene-acrylonitrile copolymers cannot be ensured. Therefore, in one specific embodiment, the second monomer mixture may contain more than 1% by weight, more than 5% by weight, more than 10% by weight, more than 11% by weight, more than 12% by weight, more than 13% by weight, more than 14% by weight, more than 15% by weight, more than 16% by weight, more than 17% by weight, more than 18% by weight, more than 19% by weight, or more than 20% by weight, and less than 27% by weight, less than 26% by weight, less than 25% by weight, less than 24% by weight, less than 23% by weight, less than 22% by weight, less than 21% by weight, or less than 20% by weight of vinyl cyanide monomers.

[0052] According to one embodiment of the invention, the second monomer mixture may contain 73% by weight or more, 74% by weight or more, 75% by weight or more, 76% by weight or more, 77% by weight or more, 78% by weight or more, 79% by weight or more, or 80% by weight or more, and less than 99% by weight, less than 95% by weight, less than 90% by weight, less than 89% by weight, less than 88% by weight, less than 87% by weight, less than 86% by weight, less than 85% by weight, less than 84% by weight, less than 83% by weight, less than 82% by weight, less than 81% by weight, or less than 80% by weight, of aromatic vinyl monomers, depending on the amount of vinyl cyanide monomers. In addition to aromatic vinyl monomers and vinyl cyanide monomers, the second monomer mixture may also contain vinyl monomers that can be copolymerized with conjugated diene polymers, aromatic vinyl monomers, and vinyl cyanide monomers, as needed.

[0053] According to one embodiment of the invention, based on the total injection amount of 100 parts by weight of the conjugated diene polymer, aromatic vinyl monomer, and vinyl cyanide monomer injected during the preparation of the graft copolymer, the second monomer mixture can be injected at amounts from 10 parts by weight to 45 parts by weight. In a specific embodiment, based on the total injection amount of 100 parts by weight of the conjugated diene polymer, aromatic vinyl monomer, and vinyl cyanide monomer, the second monomer mixture can be 10 parts or more, 15 parts or more, 20 parts or more, or 25 parts by weight, and less than 45 parts by weight, less than 40 parts by weight, less than 35 parts by weight, or less than 30 parts by weight. Within this range, compatibility degradation between the graft copolymer and the matrix resin can be prevented, and impact resistance can be improved.

[0054] According to one embodiment of the present invention, the aromatic vinyl monomer may be one or more selected from styrene, α-methylstyrene, 3-methylstyrene, 4-methylstyrene, 4-propylstyrene, 1-vinylnaphthalene, 4-cyclohexylstyrene, 4-(p-methylphenyl)styrene and 1-vinyl-5-hexylnaphthalene, specifically styrene.

[0055] According to one embodiment of the present invention, the vinyl cyanide monomer may be one or more selected from acrylonitrile, methacrylonitrile, ethyl acrylonitrile, phenyl acrylonitrile and α-chloroacrylonitrile, specifically acrylonitrile.

[0056] According to one embodiment of the invention, steps (S10) and (S20) can be performed by injecting the first molecular weight regulator together with the first monomer mixture and the second monomer mixture. Similarly, the first molecular weight regulator can be injected in both steps (S10) and (S20), but it can be injected in batches with the first monomer mixture in step (S10) and continuously with the second monomer mixture in step (S20). In this case, the absolute amount of the first molecular weight regulator injected during the preparation of the graft copolymer can be reduced, and by injecting it in the same amount based on the total amount of the first molecular weight regulator as described above, the flowability of the graft copolymer can be improved, while deterioration of mechanical properties such as impact resistance can be prevented.

[0057] According to one embodiment of the present invention, the first molecular weight regulator may be one or more selected from tert-dodecyl mercaptan, n-dodecyl mercaptan, octyl mercaptan, carbon tetrachloride, dichloromethane, dibromomethane, tetraethylthiuram disulfide, dipentylthiuram disulfide, and diisopropyl xanthate disulfide, specifically tert-dodecyl mercaptan.

[0058] According to one embodiment of the present invention, based on the total injection amount of 100 parts by weight of conjugated diene polymer, aromatic vinyl monomer and vinyl cyanide monomer, the total injection amount of the first molecular weight regulator in steps (S10) and (S20) may be from 0.20 parts by weight to 0.40 parts by weight. In one specific embodiment, based on the total injection amount of 100 parts by weight of the conjugated diene polymer, the aromatic vinyl monomer, and the vinyl cyanide monomer, the total injection amount of the first molecular weight regulator in steps (S10) and (S20) can be 0.20 parts by weight or more, 0.21 parts by weight or more, 0.22 parts by weight or more, 0.23 parts by weight or more, 0.24 parts by weight or more, 0.25 parts by weight or more, 0.26 parts by weight or more, 0.27 parts by weight or more, 0.28 parts by weight or more, 0.29 parts by weight or more, or 0.30 parts by weight or less, and less than 0.40 parts by weight, less than 0.38 parts by weight, less than 0.36 parts by weight, less than 0.34 parts by weight, less than 0.32 parts by weight, less than 0.30 parts by weight, less than 0.28 parts by weight, less than 0.26 parts by weight, less than 0.24 parts by weight, or less than 0.22 parts by weight.

[0059] According to one embodiment of the invention, in addition to the first molecular weight regulator, step (20) can be performed by continuously injecting a second monomer mixture together with a second molecular weight regulator different from the first molecular weight regulator. In this case, unlike the first molecular weight regulator, the second molecular weight regulator can be injected for the purpose of changing only the grafting rate without changing the molecular weight. In a specific embodiment, the second molecular weight regulator may be one or more selected from α-methylstyrene dimer, n-dodecyl mercaptan, octyl mercaptan, carbon tetrachloride, dichloromethane, dibromomethane, tetraethylthiuram disulfide, diammonium pentoxide thiuram disulfide, and diisopropyl xanthate disulfide. In a specific embodiment, α-methylstyrene dimer may be used depending on the purpose of injecting the second molecular weight regulator.

[0060] According to one embodiment of the present invention, based on the total injection amount of 100 parts by weight of conjugated diene polymer, aromatic vinyl monomer and vinyl cyanide monomer, the total injection amount of the second molecular weight regulator in step (S20) can be from 0.01 parts by weight to 0.40 parts by weight. In one specific embodiment, based on the total injection amount of 100 parts by weight of the conjugated diene polymer, aromatic vinyl monomer, and vinyl cyanide monomer, the total injection amount of the second molecular weight regulator in step (S20) can be more than 0.01 parts by weight, more than 0.02 parts by weight, more than 0.03 parts by weight, more than 0.04 parts by weight, more than 0.05 parts by weight, more than 0.06 parts by weight, more than 0.07 parts by weight, more than 0.08 parts by weight, more than 0.09 parts by weight, or more than 0.10 parts by weight, and less than 0.40 parts by weight, less than 0.35 parts by weight, less than 0.30 parts by weight, less than 0.25 parts by weight, less than 0.20 parts by weight, less than 0.18 parts by weight, less than 0.16 parts by weight, less than 0.15 parts by weight, less than 0.14 parts by weight, less than 0.13 parts by weight, less than 0.12 parts by weight, less than 0.11 parts by weight, or less than 0.10 parts by weight. Within this range, the grafting rate can be changed without altering the molecular weight.

[0061] According to one embodiment of the present invention, the graft polymerization in steps (S10) and (S20) can be carried out by emulsion polymerization, and the emulsion polymerization can be carried out in the presence of a modifier. The emulsifier can be one or more selected from anionic emulsifiers, cationic emulsifiers, and nonionic emulsifiers. In a specific embodiment, it can be one or more selected from alkyl aryl sulfonates, basic methyl alkyl sulfates, fatty acid soaps, basic oleates, basic rosin salts, basic laurates, sodium diethylhexyl phosphate, phosphonated polyoxyethylene alcohol, and phosphonated polyoxyethylene phenol.

[0062] According to one embodiment of the present invention, the graft polymerization in steps (S10) and (S20) can be carried out via free radical polymerization using a peroxide initiator, a redox initiator, or an azo initiator. The redox initiator can be one or more selected from tert-butyl hydroperoxide, diisopropylbenzene hydroperoxide, and cumene hydroperoxide, thus providing a stable polymerization environment. Alternatively, if a redox initiator is used, polymerization can be carried out by further including ferrous sulfate, glucose, or sodium pyrophosphate as a redox catalyst.

[0063] According to one embodiment of the present invention, the graft polymerization in steps (S10) and (S20) can be carried out in an aqueous solvent, and the aqueous solvent can be ion-exchanged water. Therefore, the graft copolymer prepared in step (S20) can be obtained as an example of a latex-type graft copolymer dispersed as a colloidal phase in an aqueous solvent.

[0064] This invention provides a graft copolymer.

[0065] According to one embodiment of the present invention, the graft copolymer may be a graft copolymer prepared according to the above-described method for preparing graft copolymers. In a specific embodiment, the graft copolymer may comprise: a conjugated diene polymer; a first graft layer formed by permeation into or on the exterior of the conjugated diene polymer; and a second graft layer formed by encapsulating the first graft layer, wherein the first graft layer comprises 60 wt% to 85 wt% aromatic vinyl monomer units and 15 wt% to 40 wt% vinyl cyanide monomer units, and the second graft layer comprises 73 wt% to 99 wt% aromatic vinyl monomer units and 1 wt% to 27 wt% vinyl cyanide monomer units.

[0066] According to one embodiment of the present invention, the conjugated diene polymer may be derived from the conjugated diene polymer latex injected in step (S10) of the method for preparing the graft copolymer, the first graft layer may be derived from the first monomer mixture injected in step (S10) of the method for preparing the graft copolymer, and the second graft layer may be derived from the second monomer mixture injected in step (S20) of the method for preparing the graft copolymer.

[0067] According to one embodiment of the present invention, the graft copolymer may contain a conjugated diene polymer depending on the amount of conjugated diene polymer injected in the method of preparing the graft copolymer, and the first graft layer and the second graft layer may further contain aromatic vinyl monomer units and vinyl cyanide monomer units depending on the amount of the first monomer mixture and the second monomer mixture injected in the method of preparing the graft copolymer, the amount of each monomer in the first monomer mixture and the amount of each monomer in the second monomer mixture.

[0068] According to one embodiment of the present invention, the graft copolymer can be grafted and polymerized step by step according to the steps (S10) and (S20) of the above-described method for preparing the graft copolymer, and can exhibit the above-described structural specificity.

[0069] According to one embodiment of the invention, the grafting rate of the graft copolymer can be from 34.0% to 44.0%. The grafting rate can be controlled by a second molecular weight regulator in the method for preparing the graft copolymer, and in a specific embodiment, it can be above 34.0%, above 36.0%, above 38.0%, above 38.5%, or above 38.6%, and below 44.0%, below 43.0%, below 42.5%, or below 42.2%. Within this range, together with the content of vinyl cyanide monomer units in the first and second graft layers, sufficient impact resistance and flowability for general-purpose matrix resins such as styrene-acrylonitrile copolymers can be ensured, and degradation of impact strength for heat-resistant matrix resins such as α-methylstyrene-acrylonitrile copolymers can be prevented.

[0070] According to one embodiment of the present invention, the weight-average molecular weight of the graft copolymer can be from 80,000 g / mol to 95,000 g / mol. The weight-average molecular weight can be controlled by a first molecular weight regulator in the method for preparing the graft copolymer, and can specifically be 80,000 g / mol or more, 80,400 g / mol or more, 81,000 g / mol or more, 81,500 g / mol or more, or 81,800 g / mol or more, and 95,000 g / mol or less, 94,000 g / mol or less, 93,000 g / mol or less, 92,000 g / mol or less, 91,000 g / mol or less, 90,000 g / mol or less, 89,000 g / mol or less, or 88,000 g / mol or less. Within this range, together with the content of vinyl cyanide monomer units in the first and second graft layers, the impact strength and flowability of general-purpose matrix resins such as styrene-acrylonitrile copolymers can be adequately ensured, and the deterioration of the impact strength of heat-resistant matrix resins such as α-methylstyrene-acrylonitrile copolymers can be prevented.

[0071] The present invention provides a resin composition.

[0072] According to one embodiment of the invention, the resin composition may comprise the graft copolymer and a matrix resin. The graft copolymer can be prepared according to the method for preparing the graft copolymer, and can improve flowability and processability while maintaining impact properties at the same or better level, regardless of the type of matrix resin. Therefore, regardless of the type of matrix resin, the resin composition can have excellent impact resistance and processability.

[0073] According to one embodiment of the invention, based on the total amount of 100 parts by weight of the graft copolymer and the matrix resin, the resin composition may contain 10 to 40 parts by weight of the graft copolymer, specifically, more than 10 parts by weight, more than 15 parts by weight, more than 20 parts by weight, more than 21 parts by weight, more than 22 parts by weight, more than 23 parts by weight, more than 24 parts by weight, or more than 25 parts by weight, and less than 40 parts by weight, less than 35 parts by weight, less than 30 parts by weight, less than 29 parts by weight, less than 28 parts by weight, less than 27 parts by weight, less than 26 parts by weight, or less than 25 parts by weight. In this case, the amount of graft copolymer applied in the resin composition can be varied depending on the type of matrix resin.

[0074] According to one embodiment of the invention, depending on the amount of graft copolymer, based on the total amount of 100 parts by weight of graft copolymer and matrix resin, the resin composition may contain 60 to 90 parts by weight of matrix resin, specifically, more than 60 parts by weight, more than 65 parts by weight, more than 70 parts by weight, more than 71 parts by weight, more than 72 parts by weight, more than 73 parts by weight, more than 74 parts by weight, or more than 75 parts by weight, and less than 90 parts by weight, less than 85 parts by weight, less than 80 parts by weight, less than 79 parts by weight, less than 78 parts by weight, less than 77 parts by weight, less than 76 parts by weight, or less than 75 parts by weight. In this case, the amount of matrix resin applied in the resin composition can be varied depending on the type of matrix resin.

[0075] According to one embodiment of the present invention, the matrix resin may comprise aromatic vinyl monomer units and vinyl cyanide monomer units. Here, the aromatic vinyl monomer used to form the aromatic vinyl monomer unit may be one or more selected from styrene, α-methylstyrene, 3-methylstyrene, 4-methylstyrene, 4-propylstyrene, 1-vinylnaphthalene, 4-cyclohexylstyrene, 4-(p-methylphenyl)styrene, and 1-vinyl-5-hexylnaphthalene, specifically styrene or α-methylstyrene. Additionally, the vinyl cyanide monomer used to form the vinyl cyanide monomer unit may be one or more selected from acrylonitrile, methacrylonitrile, ethylacrylonitrile, phenylacrylonitrile, and α-chloroacrylonitrile, specifically acrylonitrile.

[0076] According to one embodiment of the present invention, if the resin composition comprises a general matrix resin as the matrix resin of the resin composition, the matrix resin may comprise styrene monomer units and vinyl cyanide monomer units, specifically, styrene-acrylonitrile copolymers.

[0077] According to one embodiment of the present invention, if the resin composition comprises styrene monomer units and vinyl cyanide monomer units as the matrix resin, it passes ASTM... In method D1238, the flow index of the resin composition measured at 220°C and 10 kg can be 17.0 g / 10 min or more, 17.5 g / 10 min or more, 18.0 g / 10 min or more, 18.5 g / 10 min or more, 19.0 g / 10 min or more, 19.5 g / 10 min or more, or 20.0 g / 10 min or more, and less than 25.0 g / 10 min, less than 24.5 g / 10 min, less than 24.0 g / 10 min, less than 23.5 g / 10 min, less than 23.0 g / 10 min, less than 22.5 g / 10 min, less than 22.0 g / 10 min, less than 21.5 g / 10 min, less than 21.0 g / 10 min, less than 20.5 g / 10 min, or less than 20.0 g / 10 min.

[0078] According to one embodiment of the present invention, if the resin composition comprises styrene monomer units and vinyl cyanide monomer units as the matrix resin, the impact strength of the resin composition, measured at room temperature (23°C) using a 1 / 4-inch thick specimen by the ASTM D256 method, can be ≥33.5 kgf·cm / cm, ≥34.0 kgf·cm / cm, ≥34.5 kgf·cm / cm, or ≥35.0 kgf·cm / cm, and ≤50.0 kgf·cm / cm, ≤45.0 kgf·cm / cm, ≤40.0 kgf·cm / cm, ≤39.0 kgf·cm / cm, ≤38.0 kgf·cm / cm, ≤37.0 kgf·cm / cm, or ≤36.0 kgf·cm / cm.

[0079] According to one embodiment of the present invention, if the resin composition comprises a heat-resistant matrix resin as the matrix resin, the matrix may comprise α-methylstyrene monomer units and vinyl cyanide monomer units, specifically, α-methylstyrene-acrylonitrile copolymer.

[0080] According to one embodiment of the present invention, if the resin composition comprises α-methylstyrene monomer units and vinyl cyanide monomer units as the matrix resin, the flow index of the resin composition measured at 220°C and 10 kg using the ASTM D1238 method can be 5.0 g / 10 min or more, 5.1 g / 10 min or more, 5.2 g / 10 min or more, 5.3 g / 10 min or more, 5.4 g / 10 min or more, 5.5 g / 10 min or more, 5.6 g / 10 min or more, 5.7 g / 10 min or more, 5.8 g / 10 min or more, 5.9 g / 10 min or more, or 6.0 g / 10 min or more. 6.1g / 10min or more, 6.2g / 10min or more, 6.3g / 10min or more, or 6.4g / 10min or more, and below 8.0g / 10min, 7.5g / 10min or less, 7.0g / 10min or less, 6.5g / 10min or less, 6.4g / 10min or less, 6.3g / 10min or less, 6.2g / 10min or less, 6.1g / 10min or less, 6.0g / 10min or less, or 5.5g / 10min or less.

[0081] According to one embodiment of the present invention, if the resin composition comprises α-methylstyrene monomer units and vinyl cyanide monomer units as matrix resins, the impact strength of the resin composition, measured at room temperature (23°C) using a 1 / 4-inch thick specimen by the ASTM D256 method, can be ≥13.0 kgf·cm / cm, ≥13.5 kgf·cm / cm, ≥14.0 kgf·cm / cm, ≥14.5 kgf·cm / cm, or ≥15.0 kgf·cm / cm, and ≤20.0 kgf·cm / cm, ≤19.0 kgf·cm / cm, ≤18.0 kgf·cm / cm, ≤17.0 kgf·cm / cm, ≤16.0 kgf·cm / cm, ≤15.0 kgf·cm / cm, or ≤14.0 kgf·cm / cm.

[0082] According to one embodiment of the invention, the resin composition may, as needed, contain conventional amounts of additives known in the art, such as antioxidants, heat stabilizers, processing aids, colorants, and lubricants.

[0083] The embodiments of the present invention will be described in detail below to enable those skilled in the art to readily implement the invention. However, the present invention can be implemented in various other ways and is not limited to the embodiments described herein.

[0084] Examples and Comparative Examples

[0085] Example 1

[0086] <Preparation of graft copolymers>

[0087] 100 parts by weight of deionized water and 60 parts by weight (based on solids content) of polybutadiene latex (polybutadiene average particle size 310 nm) were sequentially injected into a nitrogen-purged polymerization reactor. Then, the following monomer mixtures were added in batches to the polymerization reactor: 10.2 parts by weight of styrene and 1.8 parts by weight of acrylonitrile (acrylonitrile 15 wt%); 0.05 parts by weight of glucose; 0.03 parts by weight of tetrasodium pyrophosphate; 0.001 parts by weight of ferrous sulfate; 0.12 parts by weight of tert-butyl hydroperoxide; and 0.20 parts by weight of tert-dodecyl mercaptan as a first molecular weight regulator. The mixture was then stirred at 50°C for 30 minutes. Then, 11 parts by weight of ion-exchanged water; 20.6 parts by weight of styrene and 7.4 parts by weight of acrylonitrile (acrylonitrile is 26.4% by weight) as a second monomer mixture; 0.3 parts by weight of potassium oleate; 0.1 parts by weight of cumene hydrogen peroxide; 0.10 parts by weight of tert-dodecyl mercaptan as a first molecular weight regulator; and 0.10 parts by weight of α-methylstyrene dimer as a second molecular weight regulator are continuously injected into the polymerization reactor, and polymerization is carried out at a certain rate for 100 minutes, in which case the temperature of the polymerization reactor is raised to 70°C at a certain rate.

[0088] After the injection was completed, 0.05 parts by weight of glucose, 0.03 parts by weight of tetrasodium pyrophosphate, 0.001 parts by weight of ferrous sulfate and 0.05 parts by weight of cumene hydrogen peroxide were injected into the polymerization reactor in batches. In this case, polymerization was carried out while the temperature of the polymerization reactor was raised to 80°C over 1 hour, and the polymerization was completed to prepare the graft copolymer latex.

[0089] <Preparation of Graft Copolymer Particle Materials>

[0090] Two parts by weight of magnesium sulfate (MgSO4) were injected into 100 parts by weight (based on solids content) of the graft copolymer latex thus prepared, followed by coagulation at 82°C. The latex was then aged at 89°C for 10 minutes, followed by washing, dehydration, and drying to prepare the graft copolymer particle material.

[0091] Example 2

[0092] Except that in Example 1, 9.6 parts by weight of styrene and 2.4 parts by weight of acrylonitrile (acrylonitrile is 20% by weight) were injected instead of 10.2 parts by weight of styrene and 1.8 parts by weight of acrylonitrile (acrylonitrile is 15% by weight) as the first monomer mixture, and 21.2 parts by weight of styrene and 6.8 parts by weight of acrylonitrile (acrylonitrile is 24.3% by weight) were injected instead of 20.6 parts by weight of styrene and 7.4 parts by weight of acrylonitrile (acrylonitrile is 26.4% by weight) as the second monomer mixture, the same method as in Example 1 was performed to prepare the graft copolymer particle material.

[0093] Example 3

[0094] Except that in Example 1, 9.0 parts by weight of styrene and 3.0 parts by weight of acrylonitrile (acrylonitrile is 25% by weight) were injected instead of 10.2 parts by weight of styrene and 1.8 parts by weight of acrylonitrile (acrylonitrile is 15% by weight) as the first monomer mixture, and 21.8 parts by weight of styrene and 6.2 parts by weight of acrylonitrile (acrylonitrile is 22.1% by weight) were injected instead of 20.6 parts by weight of styrene and 7.4 parts by weight of acrylonitrile (acrylonitrile is 26.4% by weight) as the second monomer mixture, the same method as in Example 1 was performed to prepare the graft copolymer particle material.

[0095] Example 4

[0096] Except that in Example 1, 8.4 parts by weight of styrene and 3.6 parts by weight of acrylonitrile (acrylonitrile is 30% by weight) were injected instead of 10.2 parts by weight of styrene and 1.8 parts by weight of acrylonitrile (acrylonitrile is 15% by weight) as the first monomer mixture, and 22.4 parts by weight of styrene and 5.6 parts by weight of acrylonitrile (acrylonitrile is 20.0% by weight) were injected instead of 20.6 parts by weight of styrene and 7.4 parts by weight of acrylonitrile (acrylonitrile is 26.4% by weight) as the second monomer mixture, the same method as in Example 1 was performed to prepare the graft copolymer particle material.

[0097] Example 5

[0098] Except that in Example 1, 7.2 parts by weight of styrene and 4.8 parts by weight of acrylonitrile (acrylonitrile is 40% by weight) were injected instead of 10.2 parts by weight of styrene and 1.8 parts by weight of acrylonitrile (acrylonitrile is 15% by weight) as the first monomer mixture, and 23.6 parts by weight of styrene and 4.4 parts by weight of acrylonitrile (acrylonitrile is 15.7% by weight) were injected instead of 20.6 parts by weight of styrene and 7.4 parts by weight of acrylonitrile (acrylonitrile is 26.4% by weight) as the second monomer mixture, the same method as in Example 1 was performed to prepare the graft copolymer particle material.

[0099] Example 6

[0100] Except that in Example 1, 8.4 parts by weight of styrene and 3.6 parts by weight of acrylonitrile (acrylonitrile is 30% by weight) were injected instead of 10.2 parts by weight of styrene and 1.8 parts by weight of acrylonitrile (acrylonitrile is 15% by weight) as the first monomer mixture, 0.15 parts by weight of tert-dodecyl mercaptan was injected instead of 0.20 parts by weight of tert-dodecyl mercaptan as the first molecular weight regulator, and 22.4 parts by weight of styrene and 5.6 parts by weight of acrylonitrile (acrylonitrile is 20.0% by weight) were injected instead of 20.6 parts by weight of styrene and 7.4 parts by weight of acrylonitrile (acrylonitrile is 26.4% by weight) as the second monomer mixture, the same method as in Example 1 was performed to prepare the graft copolymer particle material.

[0101] Example 7

[0102] Except that in Example 1, 8.4 parts by weight of styrene and 3.6 parts by weight of acrylonitrile (acrylonitrile is 30% by weight) were injected instead of 10.2 parts by weight of styrene and 1.8 parts by weight of acrylonitrile (acrylonitrile is 15% by weight) as the first monomer mixture, 0.10 parts by weight of tert-dodecyl mercaptan was injected instead of 0.20 parts by weight of tert-dodecyl mercaptan as the first molecular weight regulator, and 22.4 parts by weight of styrene and 5.6 parts by weight of acrylonitrile (acrylonitrile is 20.0% by weight) were injected instead of 20.6 parts by weight of styrene and 7.4 parts by weight of acrylonitrile (acrylonitrile is 26.4% by weight) as the second monomer mixture, the same method as in Example 1 was performed to prepare the graft copolymer particle material.

[0103] Example 8

[0104] Except that in Example 1, 8.4 parts by weight of styrene and 3.6 parts by weight of acrylonitrile (acrylonitrile is 30% by weight) were injected instead of 10.2 parts by weight of styrene and 1.8 parts by weight of acrylonitrile (acrylonitrile is 15% by weight) as the first monomer mixture, 22.4 parts by weight of styrene and 5.6 parts by weight of acrylonitrile (acrylonitrile is 20.0% by weight) were injected instead of 20.6 parts by weight of styrene and 7.4 parts by weight of acrylonitrile (acrylonitrile is 26.4% by weight) as the second monomer mixture, and 0.05 parts by weight of α-methylstyrene dimer was injected instead of 0.10 parts by weight as the second molecular weight regulator during the injection of the second monomer mixture, the same method as in Example 1 was performed to prepare the graft copolymer particle material.

[0105] Example 9

[0106] Except that in Example 1, 8.4 parts by weight of styrene and 3.6 parts by weight of acrylonitrile (acrylonitrile is 30% by weight) were injected instead of 10.2 parts by weight of styrene and 1.8 parts by weight of acrylonitrile (acrylonitrile is 15% by weight) as the first monomer mixture, 22.4 parts by weight of styrene and 5.6 parts by weight of acrylonitrile (acrylonitrile is 20.0% by weight) were injected instead of 20.6 parts by weight of styrene and 7.4 parts by weight of acrylonitrile (acrylonitrile is 26.4% by weight) as the second monomer mixture, and 0.15 parts by weight of α-methylstyrene dimer were injected instead of 0.10 parts by weight as the second molecular weight regulator during the second monomer mixture process, the same method as in Example 1 was performed to prepare the graft copolymer particle material.

[0107] Example 10

[0108] Except that in Example 1, 8.4 parts by weight of styrene and 3.6 parts by weight of acrylonitrile (acrylonitrile is 30% by weight) were injected instead of 10.2 parts by weight of styrene and 1.8 parts by weight of acrylonitrile (acrylonitrile is 15% by weight) as the first monomer mixture, 22.4 parts by weight of styrene and 5.6 parts by weight of acrylonitrile (acrylonitrile is 20.0% by weight) were injected instead of 20.6 parts by weight of styrene and 7.4 parts by weight of acrylonitrile (acrylonitrile is 26.4% by weight) as the second monomer mixture, and 0.20 parts by weight of α-methylstyrene dimer was injected instead of 0.10 parts by weight as the second molecular weight regulator during the injection of the second monomer mixture, the same method as in Example 1 was performed to prepare the graft copolymer particle material.

[0109] Example 11

[0110] Except for injecting 65 parts by weight of polybutadiene latex instead of 60 parts by weight based on solid content in Example 1, injecting 7.35 parts by weight of styrene and 3.15 parts by weight of acrylonitrile (acrylonitrile is 30% by weight) instead of 10.2 parts by weight of styrene and 1.8 parts by weight of acrylonitrile (acrylonitrile is 15% by weight) as a first monomer mixture, injecting 0.16 parts by weight instead of 0.20 parts by weight of tert-dodecyl mercaptan as a first molecular weight regulator during the injection of the first monomer mixture, injecting 19.6 parts by weight of styrene and 4.9 parts by weight of acrylonitrile (acrylonitrile is 20.0% by weight) instead of 20.6 parts by weight of styrene and 7.4 parts by weight of acrylonitrile (acrylonitrile is 26.4% by weight) as a second monomer mixture, and injecting 0.05 parts by weight instead of 0.10 parts by weight of tert-dodecyl mercaptan as a first molecular weight regulator during the injection of the second monomer mixture, the same method as in Example 1 was performed to prepare graft copolymer particle materials.

[0111] Example 12

[0112] Except for injecting 70 parts by weight of polybutadiene latex instead of 60 parts by weight based on solid content in Example 1, injecting 6.3 parts by weight of styrene and 2.7 parts by weight of acrylonitrile (acrylonitrile is 30% by weight) instead of 10.2 parts by weight of styrene and 1.8 parts by weight of acrylonitrile (acrylonitrile is 15% by weight) as a first monomer mixture, injecting 0.10 parts by weight instead of 0.20 parts by weight of tert-dodecyl mercaptan as a first molecular weight regulator during the injection of the first monomer mixture, injecting 16.8 parts by weight of styrene and 4.2 parts by weight of acrylonitrile (acrylonitrile is 20.0% by weight) instead of 20.6 parts by weight of styrene and 7.4 parts by weight of acrylonitrile (acrylonitrile is 26.4% by weight) as a second monomer mixture, and injecting 0.05 parts by weight instead of 0.10 parts by weight of tert-dodecyl mercaptan as a first molecular weight regulator during the injection of the second monomer mixture, the same method as in Example 1 was performed to prepare graft copolymer particle materials.

[0113] Comparative Example 1

[0114] Except that in Example 1, 8.4 parts by weight of styrene and 3.6 parts by weight of acrylonitrile (acrylonitrile is 30% by weight) were injected instead of 10.2 parts by weight of styrene and 1.8 parts by weight of acrylonitrile (acrylonitrile is 15% by weight) as the first monomer mixture, and 22.4 parts by weight of styrene and 5.6 parts by weight of acrylonitrile (acrylonitrile is 20.0% by weight) were injected instead of 20.6 parts by weight of styrene and 7.4 parts by weight of acrylonitrile (acrylonitrile is 26.4% by weight) as the second monomer mixture, and α-methylstyrene dimer was not injected as a second molecular weight regulator during the injection of the second monomer mixture, the same method as in Example 1 was performed to prepare the graft copolymer particle material.

[0115] Comparative Example 2

[0116] Except that in Example 1, 12.0 parts by weight of styrene were injected instead of acrylonitrile (acrylonitrile is 0% by weight) in place of 10.2 parts by weight of styrene and 1.8 parts by weight of acrylonitrile (acrylonitrile is 15% by weight) as the first monomer mixture, and 18.8 parts by weight of styrene and 9.2 parts by weight of acrylonitrile (acrylonitrile is 32.9% by weight) were injected instead of 20.6 parts by weight of styrene and 7.4 parts by weight of acrylonitrile (acrylonitrile is 26.4% by weight) as the second monomer mixture, the same method as in Example 1 was performed to prepare the graft copolymer particle material.

[0117] Comparative Example 3

[0118] Except that in Example 1, 10.8 parts by weight of styrene and 1.2 parts by weight of acrylonitrile (acrylonitrile is 10% by weight) were injected instead of 10.2 parts by weight of styrene and 1.8 parts by weight of acrylonitrile (acrylonitrile is 15% by weight) as the first monomer mixture, and 20.0 parts by weight of styrene and 8.0 parts by weight of acrylonitrile (acrylonitrile is 28.6% by weight) were injected instead of 20.6 parts by weight of styrene and 7.4 parts by weight of acrylonitrile (acrylonitrile is 26.4% by weight) as the second monomer mixture, the same method as in Example 1 was performed to prepare the graft copolymer particle material.

[0119] Comparative Example 4

[0120] Except that in Example 1, 8.4 parts by weight of styrene and 3.6 parts by weight of acrylonitrile (acrylonitrile is 30% by weight) were injected instead of 10.2 parts by weight of styrene and 1.8 parts by weight of acrylonitrile (acrylonitrile is 15% by weight) as the first monomer mixture, and 19.6 parts by weight of styrene and 8.4 parts by weight of acrylonitrile (acrylonitrile is 30.0% by weight) were injected instead of 20.6 parts by weight of styrene and 7.4 parts by weight of acrylonitrile (acrylonitrile is 26.4% by weight) as the second monomer mixture, the same method as in Example 1 was performed to prepare the graft copolymer particle material.

[0121] Comparative Example 5

[0122] Except that in Example 1, 8.4 parts by weight of styrene and 3.6 parts by weight of acrylonitrile (acrylonitrile is 30% by weight) were injected instead of 10.2 parts by weight of styrene and 1.8 parts by weight of acrylonitrile (acrylonitrile is 15% by weight) as the first monomer mixture, tert-dodecyl mercaptan as the first molecular weight regulator was not injected during the injection of the first monomer mixture, 22.4 parts by weight of styrene and 5.6 parts by weight of acrylonitrile (acrylonitrile is 20.0% by weight) were injected instead of 20.6 parts by weight of styrene and 7.4 parts by weight of acrylonitrile (acrylonitrile is 26.4% by weight) were injected instead of 0.40 parts by weight of α-methylstyrene dimer as the second molecular weight regulator during the injection of the second monomer mixture, the same method as in Example 1 was performed to prepare the graft copolymer particle material.

[0123] Comparative Example 6

[0124] Except that in Example 1, 8.4 parts by weight of styrene and 3.6 parts by weight of acrylonitrile (acrylonitrile is 30% by weight) were injected instead of 10.2 parts by weight of styrene and 1.8 parts by weight of acrylonitrile (acrylonitrile is 15% by weight) as the first monomer mixture, 0.1 parts by weight of α-methylstyrene dimer as the second molecular weight regulator was injected instead of tert-dodecyl mercaptan as the first molecular weight regulator during the injection of the first monomer mixture, 22.4 parts by weight of styrene and 5.6 parts by weight of acrylonitrile (acrylonitrile is 20.0% by weight) were injected instead of 20.6 parts by weight of styrene and 7.4 parts by weight of acrylonitrile (acrylonitrile is 26.4% by weight) as the second monomer mixture, and 0.20 parts by weight of α-methylstyrene dimer was injected instead of 0.10 parts by weight as the second molecular weight regulator during the injection of the second monomer mixture, the same method as in Example 1 was performed to prepare the graft copolymer particle material.

[0125] Test case

[0126] Experimental Example 1

[0127] Regarding the graft copolymers prepared in Examples 1 to 12 and Comparative Examples 1 to 6, the grafting rate and weight-average molecular weight were measured by the following method, and are shown in Tables 1 to 3 together with the composition of each monomer, the weight ratio of vinyl cyanide monomers in the monomer mixture, and the injection amount of the first molecular weight regulator and the second molecular weight regulator.

[0128] *Grafting rate (%): 1 g of each graft copolymer particle material prepared in Examples 1 to 12 and Comparative Examples 1 to 6 was injected into 50 ml of acetone, stirred for 24 hours, and then subjected to sol-gel separation using a centrifuge. The precipitate was then dried at 80°C to obtain a dried product, the weight of the dried product was measured, and the grafting rate was calculated according to Formula 1.

[0129] [Mathematical Formula 1]

[0130] Grafting rate (%) = [{(weight of dried product) - (weight of conjugated diene polymer injected during polymerization)} / (weight of conjugated diene polymer during polymerization)] × 100

[0131] *Weight-average molecular weight (Mw, g / mol): The dried products of Examples 1 to 12 and Comparative Examples 1 to 6 used to measure grafting rate were dissolved in tetrahydrofuran (THF) and the weight-average molecular weight was measured by gel permeation chromatography (GPC, PL GPC220, Agilent Technologies) under the following conditions.

[0132] - Column: Polystyrene gel (Styragel)

[0133] Solvent: Tetrahydrofuran (THF)

[0134] - Flow rate: 1.0 ml / min

[0135] - Sample concentration: 1.0 mg / ml

[0136] -Injection volume: 100μl

[0137] - Column temperature: 40℃

[0138] - Detector: Waters 2414RI detector - Standard: Polystyrene (calibrated with cubic function) - Data processing: Empower

[0139] [Table 1]

[0140]

[0141] [Table 2]

[0142]

[0143] [Table 3]

[0144]

[0145] As shown in Tables 1 and 2 above, it can be confirmed that the graft copolymers of Examples 1 to 12 prepared according to the present invention exhibit appropriate levels of grafting ratio and weight-average molecular weight.

[0146] Conversely, as shown in Table 3, it can be confirmed that, compared with Examples 1 to 12, Comparative Example 2, which does not contain vinyl cyanide monomers in the first monomer mixture and contains an excess of vinyl cyanide monomers in the second monomer mixture, and Comparative Example 3, which contains a small amount of vinyl cyanide monomers in the first monomer mixture and contains an excess of vinyl cyanide monomers in the second monomer mixture, exhibited lower grafting rates and weight-average molecular weights.

[0147] Furthermore, it can be confirmed that, compared with Examples 1 to 12, Comparative Example 6, in which no molecular weight regulator was injected during the injection of the first monomer mixture and in which no first molecular weight regulator was injected during the injection of the second monomer mixture, and Comparative Example 6, in which a second molecular weight regulator was injected instead of the first molecular weight regulator during the injection of the first monomer mixture and in which no first molecular weight regulator was injected during the injection of the second monomer mixture, exhibited a higher grafting rate, and in particular, Comparative Example 6 also exhibited a higher weight-average molecular weight.

[0148] Experimental Example 2

[0149] For each graft copolymer prepared in Examples 1 to 12 and Comparative Examples 1 to 6, a first resin composition and a second resin composition were prepared by the following method, and the impact strength and flow index of each resin composition were measured and shown in Tables 4 to 6.

[0150] <Preparation of the first resin composition>

[0151] Using a Henschel mixer, 27.5 parts by weight of each graft copolymer particle material prepared in Examples 1 to 12 and Comparative Examples 1 to 6, 72.5 parts by weight of styrene-acrylonitrile copolymer (LG Chem, 92HR), 1.0 part by weight of lubricant (ethylene bis-stearamide), 0.2 parts by weight of magnesium stearate as a stabilizer, and 0.2 parts by weight of distearate pentaerythritol diphosphate were homogeneously mixed and then extruded to produce granules.

[0152] <Preparation of the Second Resin Composition>

[0153] Using a Henschel mixer, 24 parts by weight of each graft copolymer particle material prepared in Examples 1 to 12 and Comparative Examples 1 to 6, 76 parts by weight of α-methylene styrene-acrylonitrile copolymer (LG Chem, 200UH), 1.0 part by weight of lubricant (ethylene bis-stearamide), 0.2 parts by weight of Songnox 1076 (SONGWON Industrial Co.) as a stabilizer, and 0.2 parts by weight of Wingstay-L were homogenized and then extruded to produce granules.

[0154] *Impact strength (kgf·cm / cm): According to ASTM D256 method, using a 1 / 4-inch thick specimen, notches are made on the specimen at room temperature (23°C), and the impact strength of the notched cantilever beam is measured.

[0155] *Flow index (g / 10min): Measured according to ASTM D1238 method at 220°C and 10kg.

[0156] [Table 4]

[0157]

[0158] [Table 5]

[0159]

[0160] [Table 6]

[0161]

[0162] As shown in Tables 4 to 6, it can be confirmed that, compared with the first resin composition and the second resin composition of Comparative Example 1, in which no second molecular weight regulator was injected during the injection of the second monomer mixture, the respective first resin compositions and second resin compositions of Examples 1 to 12 prepared according to the present invention, despite containing different types of matrix resins, exhibit the same or improved levels of flowability and improved impact strength. In particular, in the cases of Examples 3 to 10, in which the amount of vinyl cyanide monomer in the first monomer mixture is controlled at 25% by weight or more and the amount of vinyl cyanide monomer in the second monomer mixture is controlled at 24% by weight or less, it can be confirmed that the effect is further maximized when compared with Comparative Example 1, and even when compared with Examples 1 and 2.

[0163] Conversely, it can be confirmed that the first resin composition and the second resin composition containing the graft copolymer of Comparative Example 2, in which no vinyl cyanide monomers are contained in the first monomer mixture and an excess of vinyl cyanide monomers are contained in the second monomer mixture, and the first resin composition and the second resin composition containing the graft copolymer of Comparative Example 3, in which a small amount of vinyl cyanide monomers are contained in the first monomer mixture and an excess of vinyl cyanide monomers are contained in the second monomer mixture, both exhibited rapidly decreasing impact strength. This is because the grafting ratio and weight-average molecular weight of the graft copolymers were not adequately guaranteed.

[0164] Furthermore, in Comparative Example 4, in which the second monomer mixture contains an excess of vinyl cyanide monomers; in Comparative Example 5, in which no molecular weight regulator is injected during the injection of the first monomer mixture and no first molecular weight regulator is injected during the injection of the second monomer mixture; and in Comparative Example 6, in which a second molecular weight regulator is injected instead of the first molecular weight regulator during the injection of the first monomer mixture and no second molecular weight regulator is injected during the injection of the second monomer mixture, it can be confirmed that the flow index decreases rapidly, and in particular, it can be confirmed that in Comparative Examples 5 and 6, the impact strength of the first resin composition deteriorates.

[0165] These results confirm that resin compositions comprising the graft copolymer prepared according to the method of preparing graft copolymers according to the present invention and the matrix resin exhibit improved flowability and subsequently improved processing properties, while maintaining the same or better level of impact properties, regardless of the type of matrix resin.

Claims

1. A method for preparing a graft copolymer, the method comprising: Step S10: The first monomer mixture and the first molecular weight regulator are injected in batches and polymerized in the presence of a conjugated diene polymer latex to prepare a preliminary graft copolymer latex containing a preliminary graft copolymer. and In step S20, a second monomer mixture, a first molecular weight regulator, and a second molecular weight regulator different from the first molecular weight regulator are continuously injected, and polymerization is carried out in the presence of the preliminary graft copolymer latex prepared in step S10 to prepare a graft copolymer latex containing the graft copolymer. The first monomer mixture comprises 60% to 85% by weight of aromatic vinyl monomers and 15% to 40% by weight of vinyl cyanide monomers. The second monomer mixture comprises 73% to 99% by weight of aromatic vinyl monomers and 1% to 27% by weight of vinyl cyanide monomers. Wherein, based on the total injection amount of the conjugated diene polymer, the aromatic vinyl monomer and the vinyl cyanide monomer in 100 parts by weight, the injection amount of the second molecular weight regulator in step S20 is 0.01 parts by weight to 0.40 parts by weight.

2. The method for preparing graft copolymers according to claim 1, wherein, The conjugated diene polymer latex comprises a conjugated diene polymer, and Based on the total injection amount of 100 parts by weight of the conjugated diene polymer, the aromatic vinyl monomer, and the vinyl cyanide monomer, the conjugated diene polymer is injected at 50 to 80 parts by weight.

3. The method for preparing graft copolymers according to claim 1, wherein, The first monomer mixture contains 25% to 40% by weight of the vinyl cyanide monomers.

4. The method for preparing graft copolymers according to claim 1, wherein, The second monomer mixture contains 15% to 25% by weight of the vinyl cyanide monomers.

5. The method for preparing graft copolymers according to claim 1, wherein, The first molecular weight regulator is selected from one or more of tert-dodecyl mercaptan, n-dodecyl mercaptan, octyl mercaptan, carbon tetrachloride, dichloromethane, dibromomethane, tetraethylthiuram disulfide, diamethylene thiuram disulfide, and diisopropyl xanthate disulfide.

6. The method for preparing graft copolymers according to claim 1, wherein, Based on the total injection amount of the conjugated diene polymer, the aromatic vinyl monomer, and the vinyl cyanide monomer in 100 parts by weight, the total injection amount of the first molecular weight regulator in steps S10 and S20 is 0.20 to 0.40 parts by weight.

7. The method for preparing graft copolymers according to claim 1, wherein, The second molecular weight regulator is selected from one or more of α-methylstyrene dimer, n-dodecyl mercaptan, octyl mercaptan, carbon tetrachloride, dichloromethane, dibromomethane, tetraethylthiuram disulfide, diamethylene thiuram disulfide, and diisopropyl xanthate disulfide.

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