Thermoplastic resin composition and modifier for acrylic resin

Abstract

This thermoplastic resin composition contains acrylic resin and polymer particles. The polymer particles have a core, a rubber layer positioned outside the core, and a shell layer positioned outside the rubber layer. The rubber layer is formed from a reaction product of a vinyl monomer (a1) and a crosslinkable monomer (a2). The weight ratio of the rubber layer to the polymer particles is 56-70 wt.%. The vinyl monomer (a1) contains a (meth) acrylic acid ester and an aromatic vinyl compound. The weight ratio "(meth) acrylic acid ester / aromatic vinyl compound" is 3.4-4.3.

Description

Thermoplastic resin composition and modifier for acrylic resins

[0001] The present invention relates to a thermoplastic resin composition containing an acrylic resin and a modifier for acrylic resins.

[0002] Acrylic resins are excellent polymers that are widely used in large quantities in various industrial fields due to their excellent transparency, color tone, appearance, weather resistance, gloss and processability. In particular, films molded from acrylic resins utilize their excellent transparency, appearance and weather resistance, and are used in various applications such as automotive interior and exterior materials, exterior materials for electric appliances such as mobile phones and smartphones, and civil engineering and construction interior and exterior materials including floors, windows, inner and outer walls, daylighting sections, and road signs. In recent years, taking advantage of their excellent optical properties, acrylic resins have also been applied to optical members such as liquid crystal display devices and organic EL display devices.

[0003] As a method for improving the impact resistance of acrylic resins, it is known to blend polymer particles having a core-shell multilayer structure into acrylic resins. By using a rubber such as an acrylic rubber in such core-shell particles, the impact resistance can be improved while maintaining the transparency (low haze) of the acrylic resin.

[0004] However, in acrylic resins blended with core-shell particles, the haze value has temperature dependence, and it is known that even if the resin is transparent at normal temperature, a phenomenon of whitening and clouding at high temperature (so-called high-temperature whitening) tends to be observed. For this reason, use has sometimes been restricted in applications that require high transparency and are exposed to high temperatures during use, such as automotive light covers and lighting covers in particular.

[0005] As a method to solve these problems, Patent Document 1 proposes core-shell-shell particles with a radius of 70 to 125 nm obtained by sequentially polymerizing 20 to 46 parts by weight of a first composition containing 50% by weight or more of alkyl methacrylate, 35 to 55 parts by weight of a second composition with a low Tg containing 80% by weight or more of (meth)acrylate and a crosslinkable monomer, and 10 to 30 parts by weight of a third composition containing 50% by weight or more of alkyl methacrylate, as polymer particles to be blended into an acrylic resin. In these particles, the second composition forms a rubber layer.

[0006] Patent Document 2 discloses core-shell-shell particles having the same configuration as Patent Document 1 and a radius of 125 to 180 nm.

[0007] Special table 2016-514743 publication Special table 2017-531704 publication

[0008] Patent documents 1 and 2 describe that good impact resistance can be achieved while suppressing high-temperature whitening. However, in the core-shell type particles described in these documents, the proportion of the rubber layer is limited to 35 to 55% by weight, and in some cases, the impact resistance was not fully exhibited.

[0009] The inventors investigated and concluded that the cause of high-temperature whitening is the significant difference in the temperature dependence of the refractive index of the acrylic resin and the refractive index of the core-shell type particles. In a compound material containing both components, if the refractive indices of both components are matched at room temperature to ensure transparency at room temperature, the difference in the temperature dependence of the refractive indices leads to a large difference in refractive indices at high temperatures, and this difference in refractive indices is thought to cause the whitening phenomenon at high temperatures.

[0010] Furthermore, the change in refractive index of core-shell particles with respect to temperature changes tends to increase as the rubber component content increases. Therefore, it is believed that Patent Documents 1 and 2 reduce high-temperature whitening by limiting the rubber component content in core-shell particles to 55% by weight or less, thereby bringing the temperature dependence of the refractive index of core-shell particles closer to that of acrylic resins. However, reducing the rubber component content leads to a decrease in impact resistance.

[0011] In view of the above situation, the present invention aims to provide a thermoplastic resin composition that contains an acrylic resin as the thermoplastic resin, exhibits good impact resistance, and suppresses whitening at high temperatures.

[0012] The inventors of the present invention diligently studied to solve the above problems and found that the problems could be solved by controlling the ratio of (meth)acrylic acid ester and aromatic vinyl compound in the rubber layer contained in core-shell type particles to a specific range, and by setting the content ratio of the rubber layer to a specific range, thus leading to the present invention.

[0013] In other words, the present invention relates to a thermoplastic resin composition comprising an acrylic resin and polymer particles, wherein the polymer particles have a core, a rubber layer located outside the core, and a shell layer located outside the rubber layer, the rubber layer is formed from a reaction product of a vinyl monomer (a1) and a crosslinkable monomer (a2), the weight ratio of the rubber layer to the polymer particles is 56 to 70% by weight, the vinyl monomer (a1) comprises a (meth)acrylic acid ester and an aromatic vinyl compound, and the weight ratio of the (meth)acrylic acid ester to the aromatic vinyl compound is 3.4 to 4.3.

[0014] According to the present invention, it is possible to provide a thermoplastic resin composition containing an acrylic resin as the thermoplastic resin, exhibiting good impact resistance and suppressing whitening at high temperatures. According to the present invention, it is possible to provide an acrylic resin-containing thermoplastic resin composition that suppresses high-temperature whitening and exhibits low haze values ​​at both room temperature and high temperature.

[0015] Furthermore, we can provide a modifier for acrylic resins that can be used to provide such thermoplastic resin compositions.

[0016] Embodiments of the present invention will be described in detail below. However, the present invention is not limited to the embodiments described below, and various modifications are possible within the scope defined in the claims. Furthermore, the configurations described below can be combined in any way, and such combinations may also constitute an embodiment of the present invention.

[0017] The thermoplastic resin composition according to this disclosure contains an acrylic resin and polymer particles as the thermoplastic resin. The polymer particles function as a modifier for the acrylic resin, particularly as an impact resistance modifier.

[0018] <Polymer Particles> The polymer particles have a core-shell structure comprising a core, a rubber layer located outside the core, and a shell layer located outside the rubber layer. Hereinafter, these polymer particles will also be referred to as "core-shell type polymer particles."

[0019] The core refers to the innermost particle in a core-shell type polymer particle system.

[0020] The rubber layer is a layer located on the outside of the core so as to cover the surface of the core, and is made of rubber. However, although the rubber layer covers the surface of the core, it is not limited to covering the entire surface of the core, but is sufficient if it covers at least a part of the surface of the core.

[0021] The shell layer refers to a polymer layer located outside the rubber layer so as to cover its surface. However, while the shell layer covers the surface of the rubber layer, it is not limited to covering the entire surface of the rubber layer; it is sufficient if it covers at least a portion of the rubber layer's surface. The shell layer is sometimes also called the graft layer.

[0022] <Core> The innermost core of the polymer particles has the function of suppressing flattening of the core-shell type polymer particles and maintaining their shape. For this reason, the core is preferably made of a rigid polymer.

[0023] Here, "hard" means that the glass transition temperature of the polymer is 20°C or higher. The glass transition temperature of a polymer can be calculated using Fox's formula with values ​​listed in the Polymer Handbook [J. Brandrup, Interest 1989] (for example, the Tg of polymethyl methacrylate is 105°C, and the Tg of polybutyl acrylate is -54°C).

[0024] The glass transition temperature of the polymer constituting the core is preferably 60°C or higher, more preferably 80°C or higher, and even more preferably 90°C or higher.

[0025] From the viewpoint of obtaining a core with a high Tg and hardness, it is preferable that the core be composed of a polymer of monomer components mainly consisting of alkyl methacrylate.

[0026] The alkyl methacrylate ester is preferably one in which the alkyl group has 1 to 12 carbon atoms. Specifically, examples include methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, and octyl methacrylate. Only one alkyl methacrylate ester may be used, or two or more may be used in combination.

[0027] Among these, alkyl methacrylates having 1 to 4 carbon atoms in the alkyl group are preferred. Specifically, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, and t-butyl methacrylate are preferred. Methyl methacrylate is particularly preferred.

[0028] Of the monomer components used to constitute the core (excluding the crosslinkable monomers described later), the proportion of alkyl methacrylate is preferably 60% by weight or more, more preferably 70% by weight or more, even more preferably 80% by weight or more, and particularly preferably 90% by weight or more, from the viewpoint of increasing the Tg of the core. The upper limit may be 100% by weight or less, but from the viewpoint of ease of core manufacturing, it is preferable to be 99% by weight or less.

[0029] Examples of monomers other than alkyl methacrylates that can be used to constitute the core include alkyl acrylates and other vinyl monomers.

[0030] The alkyl acrylate ester is preferably one in which the alkyl group has 1 to 12 carbon atoms. Specifically, examples include ethyl acrylate, n-butyl acrylate, n-octyl acrylate, and 2-ethylhexyl acrylate. Only one alkyl acrylate ester may be used, or two or more may be used in combination. Among these, n-butyl acrylate is preferred.

[0031] Other vinyl monomers include methacrylic acid esters other than the alkyl methacrylate esters, acrylic acid esters other than the alkyl acrylate esters, aromatic vinyl monomers, and other copolymerizable vinyl monomers.

[0032] Examples of methacrylate esters other than the alkyl methacrylate esters mentioned above include phenyl methacrylate, benzyl methacrylate, cyclohexyl methacrylate, and isobornyl methacrylate.

[0033] Examples of acrylic acid esters other than the alkyl acrylates mentioned above include phenyl acrylate, benzyl acrylate, cyclohexyl acrylate, and isobornyl acrylate.

[0034] Examples of the aromatic vinyl monomers include styrene, α-methylstyrene, chlorostyrene, and other styrene derivatives.

[0035] Examples of the aforementioned other copolymerizable vinyl monomers include unsaturated nitrile monomers such as acrylonitrile and methacrylonitrile, α,β-unsaturated carboxylic acids such as acrylic acid, methacrylic acid, and crotonic acid, olefin monomers such as vinyl acetate, ethylene, and propylene, vinyl halogenated monomers such as vinyl chloride, vinylidene chloride, and vinylidene fluoride, and maleimide monomers such as N-ethyl maleimide, N-propyl maleimide, N-cyclohexyl maleimide, and N-o-chlorophenyl maleimide. These may be used individually or in combination of two or more.

[0036] The core may have a crosslinked structure. That is, the core may be composed of a reaction product of a monomer component containing an alkyl methacrylate and a crosslinkable monomer. As the crosslinkable monomer, a compound having two or more carbon-carbon unsaturated bonds in one molecule can be used. Specific examples include allyl methacrylate, allyl acrylate, diallyl maleate, diallyl fumarate, diallyl itaconate, monoallyl maleate, monoallyl fumarate, butadiene, divinylbenzene, triallyl isocyanurate, alkylene glycol dimethacrylate, alkylene glycol diacrylate, etc. Only one of these may be used, or two or more may be used. Preferably, allyl methacrylate is used.

[0037] When a crosslinkable monomer is used in the core, the amount used is preferably about 0.1 to 3 parts by weight per 100 parts by weight of the monomer components (excluding the crosslinkable monomer) forming the core. However, the crosslinkable monomer does not need to be used substantially in the core, and the amount used may be 0 to 0.1 parts by weight or 0 to 0.01 parts by weight per 100 parts by weight of the monomer components.

[0038] The proportion of the core in the polymer particles can be determined according to the ratio of the rubber layer to the shell layer, and is not particularly limited, but for example, it is preferably about 1 to 20% by weight, more preferably 3 to 18% by weight, and even more preferably 5 to 15% by weight.

[0039] <Rubber Layer> The rubber layer, which serves as the intermediate layer in the polymer particles, is composed of rubber. Here, rubber refers to elastic rubber, which is a material with a low elastic modulus composed of an organic material having a crosslinked structure. Since the polymer particles contain a rubber layer, impact resistance can be imparted to an acrylic resin by blending the polymer particles into the acrylic resin.

[0040] The glass transition temperature of the rubber is not particularly limited, but is preferably 0°C or lower, more preferably -10°C or lower, and still more preferably -15°C or lower. The upper limit is not particularly limited, and may for example be -60°C or higher, is preferably -50°C or higher, and more preferably -40°C or higher.

[0041] The rubber layer is formed from a reaction product of a vinyl monomer (a1) and a crosslinkable monomer (a2).

[0042] (Vinyl Monomer (a1)) A vinyl monomer refers to a compound that has one carbon-carbon unsaturated bond per molecule and has the ability to form a polymer through addition polymerization.

[0043] From the viewpoint of achieving both low haze and impact resistance, the vinyl monomer (a1) contains at least a (meth)acrylic acid ester and an aromatic vinyl compound. Note that "(meth)acrylic" is a notation that refers to both acrylic and methacrylic.

[0044] The (meth)acrylic acid ester is not particularly limited, and examples thereof include: (meth)acrylic acid alkyl esters such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, dodecyl (meth)acrylate, stearyl (meth)acrylate, and behenyl (meth)acrylate; aromatic ring-containing (meth)acrylates such as phenoxyethyl (meth)acrylate and benzyl (meth)acrylate; hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate; glycidyl (meth)acrylates such as glycidyl (meth)acrylate and glycidyl alkyl (meth)acrylate; and alkoxyalkyl (meth)acrylates. The (meth)acrylic acid ester may be used alone, or two or more thereof may be used in combination.

[0045] The number of carbon atoms in the ester moiety of the (meth)acrylic acid ester is preferably 1 to 22, more preferably 1 to 18, still more preferably 2 to 12, and even more preferably 2 to 6.

[0046] From the viewpoint of imparting favorable elasticity to the rubber layer and improving the impact resistance of the acrylic resin, it is preferable to use an acrylic acid ester as the (meth)acrylic acid ester, and it is more preferable to use an acrylic acid alkyl ester. Among acrylic acid alkyl esters, it is particularly preferable to use butyl acrylate.

[0047] The aromatic vinyl compound which is one type of the vinyl monomer (a1) is not particularly limited, and examples thereof include styrene, α-methylstyrene, p-methylstyrene, p-isopropylstyrene, o-chlorostyrene, p-chlorostyrene, and dichlorostyrene. Only one aromatic vinyl compound may be used, or two or more thereof may be used in combination. Among these, styrene is preferred.

[0048] The vinyl monomer (a1) may consist only of the (meth)acrylic acid ester and the aromatic vinyl compound, but it may also further contain other vinyl monomers having one carbon-carbon unsaturated bond in one molecule. The other monomer is not particularly limited, but examples include vinyl cyanide compounds, vinyl halogenated compounds such as vinyl chloride and chloroprene, vinyl acetate, and alkenes such as ethylene and propylene.

[0049] In the vinyl monomer (a1), the total content of the (meth)acrylic acid ester and the aromatic vinyl compound is preferably 50 to 100% by weight, more preferably 70 to 100% by weight, even more preferably 80 to 100% by weight, even more preferably 90 to 100% by weight, and particularly preferably 95 to 100% by weight.

[0050] When an alkyl acrylate is used as the (meth)acrylic acid ester, the total content of the alkyl acrylate and aromatic vinyl compound in the vinyl monomer (a1) is preferably 50 to 100% by weight, more preferably 70 to 100% by weight, even more preferably 80 to 100% by weight, even more preferably 90 to 100% by weight, and particularly preferably 95 to 100% by weight. In this case, as the monomer other than the alkyl acrylate and aromatic vinyl compound, a (meth)acrylic acid ester other than the alkyl acrylate may be used.

[0051] The vinyl monomer (a1) used in the rubber layer comprises (meth)acrylic acid ester and aromatic vinyl compound as essential components. By controlling the ratio of these two within a specific range, the thermoplastic resin composition according to this disclosure can have good impact resistance while suppressing whitening at high temperatures. Specifically, in the rubber layer, the amounts of both monomers used are adjusted so that the weight ratio of (meth)acrylic acid ester to aromatic vinyl compound falls within the range of 3.4 to 4.3.

[0052] If the weight ratio is less than 3.4, the glass transition temperature of the rubber layer becomes relatively high, which may result in insufficient impact resistance. From this viewpoint, the weight ratio is preferably 3.5 or higher, and more preferably 3.6 or higher.

[0053] On the other hand, if the weight ratio exceeds 4.3, the refractive index of the rubber layer at high temperatures becomes too low, the refractive index difference with the acrylic resin becomes large, and high-temperature whitening tends to occur. From this viewpoint, the weight ratio is preferably 4.1 or less, and more preferably 4.0 or less.

[0054] (Crosslinkable monomer (a2)) A crosslinkable monomer (a2) is a compound having two or more carbon-carbon unsaturated bonds in one molecule that can copolymerize with the vinyl monomer (a1). Specific examples include (meth)acrylates having an allyl group, such as allyl (meth)acrylate, allylalkyl (meth)acrylate, and allyloxyalkyl (meth)acrylate; polyfunctional (meth)acrylates having two or more (meth)acrylic groups, such as (poly)ethylene glycol di(meth)acrylate, butanediol di(meth)acrylate, ethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, and tripropylene glycol di(meth)acrylate; and diallyl phthalate, triallyl cyanurate, triallyl isocyanurate, and divinylbenzene.

[0055] Among these, allyl methacrylate, triallyl isocyanurate, butanediol di(meth)acrylate, and divinylbenzene are preferred, with allyl methacrylate being particularly preferred. Only one type of crosslinkable monomer (a2) may be used, or two or more types may be used in combination.

[0056] The amount of crosslinkable monomer (a2) used can be appropriately set from the viewpoint of improving impact strength, but specifically, it is preferably about 0.01 to 5 parts by weight per 100 parts by weight of vinyl monomer (a1). Within this range, it is easy to obtain a thermoplastic resin composition with good impact resistance. More preferably it is 0.05 to 4 parts by weight, even more preferably 0.1 to 3 parts by weight, and particularly preferably 0.3 to 2 parts by weight.

[0057] According to this disclosure, by controlling the weight ratio of the rubber layer to the total polymer particles within a specific range, good impact resistance can be achieved while suppressing whitening at high temperatures. Specifically, the weight ratio of the rubber layer to the polymer particles is set to a range of 56 to 70% by weight.

[0058] If the weight percentage of the rubber layer is less than 56% by weight, the impact resistance may be insufficient. From this viewpoint, the weight percentage is preferably 60% by weight or more, more preferably 62% by weight or more, and even more preferably 64% by weight or more.

[0059] On the other hand, if the weight percentage of the rubber layer exceeds 70% by weight, the polymer particles may not disperse uniformly in the acrylic resin, which can reduce the impact resistance improvement effect or worsen haze. From this viewpoint, it is preferable that the weight percentage be 69% by weight or less.

[0060] The average particle diameter of the rubber layer is not particularly limited, but from the viewpoint of impact resistance, it is preferable that the volume average particle diameter is in the range of 125 to 400 nm. Impact resistance tends to improve as the average particle diameter increases. From this viewpoint, the lower limit is preferably 125 nm or more, more preferably 140 nm or more, even more preferably 150 nm or more, and particularly preferably 160 nm or more.

[0061] On the other hand, as the average particle size decreases, the haze tends to decrease and the transparency tends to increase. From this viewpoint, the upper limit is preferably 400 nm or less, more preferably 300 nm or less, even more preferably 250 nm or less, and particularly preferably 200 nm or less.

[0062] The average particle diameter of the rubber layer referred to here is the average particle diameter of the polymer particles after the core and rubber layer have been synthesized, but before the shell layer has been synthesized. The average particle diameter of the polymer particles is a value measured using a particle diameter measuring device while the polymer particles are in their latex state, as shown in the Examples section. The particle diameter of the rubber layer can be controlled by the type and amount of each monomer and crosslinkable monomer, the type and amount of initiators, reducing agents, emulsifiers, etc., polymerization temperature, polymerization time, etc.

[0063] (Shell layer) The shell layer is a polymer layer located on the outside of the rubber layer and is located on the surface side of the core-shell type polymer particles. Preferably, the shell layer is graft-bonded to the rubber layer, but may also include layers that are not graft-bonded. The shell layer improves the compatibility between the core-shell type polymer particles and the acrylic resin, and enables the core-shell type polymer particles to be dispersed in the resin composition as primary particles. The shell layer may consist of a single layer or of multiple layers with different compositions.

[0064] From the viewpoint of improving compatibility with acrylic resins, the shell layer is preferably composed of a polymer of at least one vinyl monomer selected from the group consisting of (meth)acrylic acid esters, aromatic vinyl compounds, and vinyl cyanide compounds.

[0065] The (meth)acrylic acid ester is not particularly limited, but examples include alkyl (meth)acrylic acid esters such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, dodecyl (meth)acrylate, stearyl (meth)acrylate, and behenyl (meth)acrylate; aromatic ring-containing (meth)acrylates such as phenoxyethyl (meth)acrylate and benzyl (meth)acrylate; hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate; glycidyl (meth)acrylates such as glycidyl (meth)acrylate and glycidylalkyl (meth)acrylate; and alkoxyalkyl (meth)acrylates.

[0066] The aromatic vinyl compound is not particularly limited, but examples include styrene, α-methylstyrene, p-methylstyrene, p-isopropylstyrene, o-chlorostyrene, p-chlorostyrene, and dichlorostyrene. Of these, styrene is preferred.

[0067] The vinyl cyanide compound is not particularly limited, but examples include acrylonitrile and methacrylonitrile. Of these, acrylonitrile is preferred.

[0068] From the viewpoint of compatibility with acrylic resins, it is particularly preferable that the monomers constituting the shell layer include at least one selected from (meth)acrylic acid esters. The total proportion of (meth)acrylic acid esters in the total monomers constituting the shell layer is preferably 50 to 100% by weight, more preferably 70 to 100% by weight, even more preferably 90 to 100% by weight, and particularly preferably 95 to 100% by weight.

[0069] In particular, the polymer constituting the shell layer is preferably a copolymer of acrylic acid ester and methacrylic acid ester. In this case, the weight ratio of acrylic acid ester to methacrylic acid ester in the entire shell layer is preferably 1:99 to 50:50, more preferably 2:98 to 40:60, even more preferably 3:97 to 30:70, and particularly preferably 4:96 to 20:80.

[0070] The shell layer may consist of a single layer, or it may consist of multiple layers with different monomer compositions.

[0071] The shell layer may be formed from a polymer having a crosslinked structure, but it is preferable that it be formed from a polymer without a crosslinked structure. That is, it is preferable that the shell layer be formed from a polymer synthesized without using a crosslinkable monomer.

[0072] The proportion of the shell layer in the polymer particles can be determined according to the proportion of the rubber layer and is not particularly limited, but from the viewpoint of balancing the compatibility of the shell layer with the acrylic resin and the improvement of impact resistance by the rubber layer, it is preferably about 10 to 35% by weight, more preferably 15 to 30% by weight, and even more preferably 18 to 25% by weight.

[0073] <Method for producing core-shell polymer particles> In producing the core-shell polymer particles, although not particularly limited, methods such as emulsion polymerization, miniemulsion polymerization, microemulsion polymerization, and soap-free emulsion polymerization can be used. Of these, emulsion polymerization is preferred.

[0074] The emulsifier that can be used in emulsion polymerization is not particularly limited, and anionic surfactants, nonionic surfactants, cationic surfactants, amphoteric surfactants, etc., can be used. Dispersants such as polyvinyl alcohol, alkyl-substituted cellulose, polyvinylpyrrolidone, and polyacrylic acid derivatives may also be used in combination.

[0075] The anionic surfactant is not particularly limited, but examples include the following compounds: fatty acid soaps such as potassium laurate, potassium coconut fatty acid, potassium myristate, potassium oleate, potassium oleate diethanolamine salt, sodium oleate, potassium palmitate, potassium stearate, sodium stearate, mixed fatty acid sodium soap, semi-hardened beef tallow fatty acid sodium soap, castor oil potassium soap; alkyl sulfurs such as sodium dodecyl sulfate, higher alcohol sulfate, dodecyl sulfate triethanolamine, dodecyl sulfate ammonium, polyoxyethylene alkyl ether sulfate sodium, polyoxyethylene alkyl ether sulfate triethanolamine, polyoxyethylene alkylphenyl ether sulfate sodium, and 2-ethylhexyl sulfate sodium. Acid ester salts; sodium alkylbenzenesulfonates such as sodium dodecylbenzenesulfonate; sodium dialkyl sulfosuccinates such as sodium di-2-ethylhexyl sulfosuccinate; sodium alkylnaphthalenesulfonate; sodium alkyldiphenyl ether disulfonate; potassium alkyl phosphate salts; phosphate ester salts such as sodium polyoxyethylene lauryl ether phosphate; sodium salts of naphthalenesulfonic acid formalin condensates; polycarboxylic acid type polymer anions; sodium acyl(tallow)methyltaurate; sodium acyl(coconut)methyltaurate; sodium cocoyl isethionate; sodium α-sulfo fatty acid ester salts; sodium amide ethersulfonate; oleyl sarcosine; sodium lauroyl sarcosinate; rosinic acid soap, etc.

[0076] The nonionic surfactant is not particularly limited, but examples include the following compounds: polyoxyethylene alkyl allyl ethers or polyoxyethylene alkyl ethers such as polyoxyethylene nonylphenyl ether, polyoxyethylene oleyl ether, and polyoxyethylene lauryl ether; polyoxyethylene sorbitan esters such as polyoxyethylene sorbitan monolaurate and polyoxyethylene sorbitan monostearate; polyoxyethylene fatty acid esters such as polyethylene glycol monolaurate, polyethylene glycol monostearate, and polyethylene glycol monooleate; and oxyethylene / oxypropylene block copolymers.

[0077] The cationic surfactant is not particularly limited, but examples include the following compounds: alkylamine salts such as coconutamine acetate, stearylamine acetate, octadecylamine acetate, and tetradecylamine acetate; and quaternary ammonium salts such as lauryltrimethylammonium chloride, stearyltrimethylammonium chloride, cetyltrimethylammonium chloride, distearyldimethylammonium chloride, alkylbenzyldimethylammonium chloride, hexadecyltrimethylammonium chloride, and behenyltrimethylammonium chloride.

[0078] The aforementioned amphoteric surfactants are not particularly limited, but examples include the following compounds: alkyl betaines such as lauryl betaine, stearyl betaine, and dimethyl lauryl betaine; sodium lauryl diaminoethylglycine; amide betaine; imidazoline; lauryl carboxymethyl hydroxyethyl imidazolinium betaine, etc.

[0079] These emulsifiers may be used individually or in combination of two or more. Preferred emulsifiers are sodium dialkyl sulfosuccinate or surfactants having an oxyethylene structure, with sodium polyoxyethylene lauryl ether phosphate being particularly preferred. The average particle size of the polymer particles can be controlled by adjusting the amount of emulsifier used.

[0080] When employing emulsion polymerization, known polymerization initiators, namely 2,2'-azobisisobutyronitrile, hydrogen peroxide, potassium persulfate, and ammonium persulfate, can be used as thermal decomposition initiators.

[0081] In addition, a redox-type initiator can be used in combination with an organic peroxide such as t-butyl peroxyisopropyl carbonate, paramenthane hydroperoxide, cumene hydroperoxide, dicumyl peroxide, t-butyl hydroperoxide, di-t-butyl peroxide, and t-hexyl peroxide; an inorganic peroxide such as hydrogen peroxide, potassium persulfate, sodium persulfate, and ammonium persulfate; and at least one reducing agent selected from the group consisting of sodium formaldehyde sulfoxylate, glucose, transition metal salts such as iron(II) sulfate, chelating agents such as ethylenediaminetetraacetate disodium; and pyrophosphates such as sodium pyrophosphate.

[0082] When a redox-type initiator is used, polymerization can be carried out even at low temperatures in which the peroxide does not substantially decompose thermally, and the polymerization temperature can be set over a wide range, which is preferable. In particular, it is preferable to use organic peroxides such as cumene hydroperoxide, dicumyl peroxide, and t-butyl hydroperoxide as redox-type initiators. The amount of the initiator used, and when a redox-type initiator is used, the amounts of the reducing agent, transition metal salt, chelating agent, etc., may be within a known range. Surfactants can also be used in addition, but this is also within a known range.

[0083] Any solvent that allows emulsion polymerization to proceed stably can be used as the solvent; for example, water can be suitably used.

[0084] The temperature during emulsion polymerization is not particularly limited, as long as the emulsifier is uniformly dissolved in the solvent. For example, it is 40 to 90°C, preferably 45 to 85°C, and more preferably 49 to 80°C.

[0085] The core-shell type polymer particles can be manufactured by following the steps (I) to (III) in order. Step (I): First, monomer components such as alkyl methacrylate are polymerized in the presence of water, an emulsifier, and an initiator to form hard core particles.

[0086] Step (II): A vinyl monomer (a1) and a crosslinkable monomer (a2), and optionally an initiator and / or emulsifier, are added to the emulsion containing the formed hard core particles to carry out polymerization, forming a rubber layer that coats the hard core particles and forming polymer particles containing the rubber layer.

[0087] Step (III): At least one vinyl monomer selected from the group consisting of (meth)acrylic acid esters, aromatic vinyl compounds, and vinyl cyanide compounds, and optionally an initiator and / or emulsifier are added to an emulsion containing polymer particles including the formed rubber layer to polymerize the vinyl monomer to form a shell layer that covers the rubber layer and obtain the core-shell type polymer particles.

[0088] In each step, the polymerization reaction may be carried out in the presence of a chain transfer agent. This allows for control of the molecular weight of the polymers forming each layer, thereby improving the impact resistance of the thermoplastic resin composition. The chain transfer agent is not particularly limited, but examples include mercaptan-based chain transfer agents such as n-butyl mercaptan, n-octyl mercaptan, n-hexadecyl mercaptan, n-dodecyl mercaptan, n-tetradecyl mercaptan, sec-butyl mercaptan, sec-dodecyl mercaptan, and t-dodecyl mercaptan, as well as thioglycolic acid esters such as 2-ethylhexyl thioglycolate, and thiophenols. The amount of the chain transfer agent used should be appropriately set considering the molecular weight of the polymers forming each layer.

[0089] After the core-shell type polymer particles are formed, one or more coagulants selected from the group consisting of acids and salts are added to the latex to solidify it, and the core-shell type polymer particles can be separated by heat treatment at a temperature of 40°C to 110°C, washing and dewatering, drying, and sieving with a sieve of a predetermined size.

[0090] <Resin Composition> By blending the core-shell type polymer particles with an acrylic resin to form a resin composition, the impact resistance of the acrylic resin can be improved.

[0091] The acrylic resin may be any resin whose constituent unit is a vinyl monomer containing (meth)acrylic acid ester, and known thermoplastic acrylic resins can be used. In particular, thermoplastic acrylic resins containing structural units derived from methacrylic acid ester are preferred, and thermoplastic acrylic resins containing 30% by weight or more, more preferably 50% by weight or more, of alkyl methacrylate ester units having 1 to 4 carbon atoms in the alkyl group are even more preferred. From the viewpoint of thermal stability, it is particularly preferable to use methyl methacrylate.

[0092] Other vinyl monomers copolymerizable with methyl methacrylate include, specifically, ethyl methacrylate, propyl methacrylate, butyl methacrylate, cyclohexyl methacrylate, 2-ethylhexyl methacrylate, benzyl methacrylate, octyl methacrylate, glycidyl methacrylate, epoxycyclohexylmethyl methacrylate, dimethylaminoethyl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, and dicyclopentanyl methacrylate. , 2,2,2-trifluoroethyl methacrylate, 2,2,2-trichloroethyl methacrylate, isobolonyl methacrylate, methacrylamide, N-methylol methacrylamide and other methacrylic acid esters; methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, glycidyl acrylate, epoxycyclohexylmethyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate Examples include acrylic acid esters such as ropil, acrylamide, and N-methylolacrylamide; carboxylic acids and their salts such as methacrylic acid and acrylic acid; vinyl cyanides such as acrylonitonyl and methacrylonitrile; vinylarenes such as styrene, α-methylstyrene, monochlorostyrene, and dichlorostyrene; maleimides such as N-phenylmaleimide, N-cyclohexylmaleimide, and N-methylmaleimide; maleic acid, fumaric acid, and their esters; halogenated vinyls such as vinyl chloride, vinyl bromide, and chloroprene; vinyl esters such as vinyl formate, vinyl acetate, and vinyl propionate; alkenes such as ethylene, propylene, butylene, butadiene, and isobutylene; halogenated alkenes; and crosslinkable monomers such as allyl methacrylate, diallyl phthalate, triallyl cyanurate, monoethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, and divinylbenzene. These vinyl monomers can be used individually or in combination of two or more types.

[0093] Other vinyl monomers copolymerizable with methyl methacrylate include (meth)acrylic acid esters (excluding methyl methacrylate) having 1 to 10 carbon atoms in the alkyl group.

[0094] From the viewpoint of optical properties, appearance, weather resistance and heat resistance, the acrylic resin preferably contains methyl methacrylate as a structural unit in an amount of 30 to 100% by weight, more preferably 50 to 100% by weight, even more preferably 50 to 99.9% by weight, and particularly preferably 50 to 98% by weight, and other vinyl monomers copolymerizable with methyl methacrylate preferably in an amount of 70 to 0% by weight, more preferably 50 to 0% by weight, even more preferably 50 to 0.1% by weight, and particularly preferably 50 to 2% by weight.

[0095] From the viewpoint of impact resistance, low haze, and suppression of high-temperature whitening, the content of the core-shell type polymer particles in the thermoplastic resin composition is preferably 3 to 70% by weight, more preferably 5 to 60% by weight, even more preferably 10 to 50% by weight, and particularly preferably 15 to 40% by weight.

[0096] The thermoplastic resin composition may further contain thermoplastic resins other than acrylic resins. Such thermoplastic resins are not particularly limited, but examples include vinyl chloride resins, polycarbonate resins, styrene-acrylonitrile copolymer resins (AS resins), amide resins, polyester resins, and the like. These may be used individually or in combination of two or more.

[0097] The content of thermoplastic resins other than acrylic resins is not particularly limited, but may be 0 to 100 parts by weight, 0 to 50 parts by weight, 0 to 30 parts by weight, 0 to 10 parts by weight, 0 to 5 parts by weight, or 0 to 1 part by weight per 100 parts by weight of acrylic resin. It may also be less than 1 part by weight.

[0098] The thermoplastic resin composition may optionally contain flame retardants, antibacterial agents, mold release agents, nucleating agents, plasticizers, antioxidants, heat stabilizers, light stabilizers, ultraviolet absorbers, compatibilizers, pigments, dyes, antistatic agents, lubricants, etc. The amount of each additive can be appropriately determined by those skilled in the art. These may be used individually or in combination of two or more.

[0099] In particular, phenolic, sulfuric, phosphorusic, and hindered amine-based antioxidants or stabilizers; benzophenone-based and benzotriazole-based ultraviolet absorbers; organopolysiloxanes, aliphatic hydrocarbons, esters of higher fatty acids and higher alcohols, amides or bisamides of higher fatty acids and their modified forms, oligoamides, and metal salts of higher fatty acids can be suitably added as internal and external lubricants.

[0100] The thermoplastic resin composition can be manufactured, for example, by mixing the core-shell polymer particles and a thermoplastic resin containing at least an acrylic resin in the form of latex, slurry, solution, powder, pellets, or a combination thereof. When the core-shell polymer particles and the thermoplastic resin are latex, for example, the latex can be solidified into a slurry by adding an alkaline earth metal salt such as calcium chloride, magnesium chloride, or magnesium sulfate, or an alkali metal salt such as sodium chloride or sodium sulfate, or an inorganic or organic acid such as hydrochloric acid, sulfuric acid, phosphoric acid, or acetic acid, and then dehydrated and dried. Spray drying can also be used. In this case, some of the additives, such as stabilizers, can be added to the latex or slurry in the form of a dispersion.

[0101] The thermoplastic resin composition can be formed into a target molded body by mixing the core-shell type polymer particles and the thermoplastic resin powder, pellets, etc. with any additives as needed, using a known melt kneader such as a Banbarri mixer, roll mill, single-screw extruder, or twin-screw extruder, and then forming it into a target molded body by a known molding method such as injection molding, extrusion molding, or blow molding.

[0102] The applications for the thermoplastic resin composition and its molded articles are not particularly limited, but because of their high transparency, they are particularly suitable for use as light-transmitting members. Here, a light-transmitting member refers to a general member used for applications that allow light such as visible light, infrared rays, ultraviolet rays, X-rays, and lasers to pass through the material.

[0103] Specific examples of such light-transmitting materials include, for example, lenses for general cameras, video cameras, objective lenses for laser pickups, diffraction gratings, holograms, and collimator lenses, fθ lenses for laser printers, cylindrical lenses, condenser lenses and projection lenses for liquid crystal projectors, Fresnel lenses, lenses for eyeglasses, etc., disc substrates for compact discs (CDs, CD-ROMs, etc.), MiniDiscs (MDs), and DVDs, liquid crystal light guide plates, liquid crystal films, LCD substrates, adhesives for bonding liquid crystal elements, and other components for liquid crystal elements, projector screens, optical filters, optical fibers, optical waveguides, prisms, lighting lenses, automobile headlights, medical supplies requiring sterilization, microwave oven cooking containers, housings for home appliances, toys, or recreational items.

[0104] Furthermore, as light-transmitting components related to molded films, applications include: automotive interior and exterior, personal computer interior and exterior, mobile phone interior and exterior, solar cell interior and exterior, solar cell backsheets; imaging fields such as photographic lenses, viewfinders, filters, prisms, and Fresnel lenses for cameras, VTRs, and projectors; lens fields such as pickup lenses for optical discs in CD players, DVD players, and MD players; optical recording fields for optical discs such as CDs, DVDs, and MDs; liquid crystal light guide plates, diffusers, backsheets, reflective sheets, polarizer protective films, polarizing films, transparent resin sheets, phase difference films, light diffusion films, and prism sheets. Applications include information equipment fields such as liquid crystal display films and surface protection films; optical communications fields such as optical fibers, optical switches, and optical connectors; automotive fields such as automotive headlights, taillight lenses, inner lenses, instrument covers, and sunroofs; medical equipment fields such as eyeglasses, contact lenses, endoscope lenses, and medical supplies requiring sterilization; architecture and building materials fields such as road signs, bathroom fixtures, flooring, road light-transmitting panels, lenses for double-glazed windows, daylight windows, carports, lighting lenses, lighting covers, and sizing for building materials; and microwave cooking containers (tableware), home appliance housings, toys, sunglasses, and stationery. It can also be used as a substitute for molded products using transfer foil sheets.

[0105] Since the thermoplastic resin composition according to this disclosure exhibits suppressed whitening at high temperatures, it can be particularly suitable for applications where the material may be exposed to high temperatures during use, specifically for applications such as light guides, vehicle light covers, and lighting covers.

[0106] The following items list preferred embodiments of the present disclosure, but the present invention is not limited to these items. [Item 1] A thermoplastic resin composition comprising an acrylic resin and polymer particles, wherein the polymer particles have a core, a rubber layer located outside the core, and a shell layer located outside the rubber layer, the rubber layer is formed from a reaction product of a vinyl monomer (a1) and a crosslinkable monomer (a2), the weight ratio of the rubber layer to the polymer particles is 56 to 70% by weight, the vinyl monomer (a1) comprises a (meth)acrylic acid ester and an aromatic vinyl compound, and the weight ratio of the (meth)acrylic acid ester to the aromatic vinyl compound is 3.4 to 4.3, a thermoplastic resin composition. [Item 2] The thermoplastic resin composition according to Item 1, wherein the (meth)acrylic acid ester is an alkyl acrylate. [Item 3] The thermoplastic resin composition according to Item 1 or 2, wherein the shell layer is composed of a polymer of at least one vinyl monomer selected from the group consisting of (meth)acrylic acid esters, aromatic vinyl compounds, and vinyl cyanide compounds. [Item 4] The thermoplastic resin composition according to any one of Items 1 to 3, wherein the average particle size of the rubber layer is 125 to 400 nm. [Item 5] The thermoplastic resin composition according to any one of Items 1 to 4, wherein the proportion of the polymer particles in the total of the acrylic resin and the polymer particles is 3 to 70% by weight. [Item 6] A molded article obtained by molding the thermoplastic resin composition according to any one of Items 1 to 5. [Item 7] The molded article according to Item 6, which is a light-transmitting member. [Item 8] A modifier for acrylic resins, wherein the modifier is a polymer particle, the polymer particle has a core, a rubber layer located outside the core, and a shell layer located outside the rubber layer, the rubber layer is formed from a reaction product of a vinyl monomer (a1) and a crosslinkable monomer (a2), the weight ratio of the rubber layer to the polymer particle is 56 to 70% by weight, the vinyl monomer (a1) includes a (meth)acrylic acid ester and an aromatic vinyl compound, and the weight ratio of the (meth)acrylic acid ester to the aromatic vinyl compound is 3.4 to 4.3.

[0107] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0108] The abbreviations used below represent the following compounds: MMA: Methyl methacrylate EA: Ethyl acrylate BA: n-Butyl acrylate St: Styrene AlMA: Allyl methacrylate DA: General term for di(meth)acrylic compounds TPGDA: Tripropylene glycol diacrylate PEG#600DA: Polyethylene glycol diacrylate (average molecular weight 708) n-OM: n-Octyl mercaptan t-DM: t-Dodecyl mercaptan

[0109] (Polymerization Conversion Rate) The polymerization conversion rate of the polymer obtained in polymerization was determined by the following method. Approximately 2 g of sample (polymer latex) containing the polymer was taken from the polymerization system and accurately weighed. It was dried in a hot air dryer at 120°C for 1 hour, and the weight after drying was accurately weighed as the solid content. Next, the ratio of the weighing results before and after drying was determined as the solid content ratio in the sample. Finally, the polymerization conversion rate was calculated using this solid content ratio with the following formula. In this formula, the polyfunctional monomer and chain transfer agent were treated as the starting monomer. Polymerization Conversion Rate (%) = {(Total Weight of Starting Materials × Solid Content Ratio - Total Weight of Materials Other Than Water and Monomers) / Weight of Starting Monomers} × 100

[0110] (Measurement of volume-average particle diameter of polymer particles) The volume-average particle diameter of polymer particles was measured in the polymer particle latex state. A NanoTrac Wave manufactured by Nikkiso Co., Ltd. was used as the measuring device. The calculation mode was set to UPA compatible mode.

[0111] (Izod Impact Test) The product was evaluated using the Izod impact test (at 23°C and 50% humidity) in accordance with ASTM D-256. A 1 / 4-inch test piece (with a V-notch) obtained by injection molding was used for the measurement.

[0112] (Charpy Impact Test) The product was evaluated using the Charpy impact test (23°C, 50% humidity) in accordance with ASTM D-6110. A 1 / 8-inch test piece (without notches) obtained by injection molding was used for the measurement.

[0113] (Haze Value) The haze value of the resin composition (molded body) was measured using the NDH-4000 manufactured by Nippon Denshoku Industries Co., Ltd., according to the method described in JIS K7105. A 3 mm thick flat plate test specimen made by injection molding was used for the measurement. The haze value at 60°C was measured by curing a 3 mm thick flat plate test specimen in a 75°C oven for 3 to 5 hours, removing the molded body from the oven, and measuring the haze value using a non-contact thermometer when the surface temperature reached 60°C, in the same manner as above.

[0114] (Manufacturing Example 1) <Production of Polymer Particles> The following substances were charged into an 8L polymerization apparatus equipped with a stirrer: Deionized water 130 parts (by weight; the same applies below) Sodium polyoxyethylene lauryl ether phosphate 0.03 parts Sodium carbonate 0.04725 parts EDTA / FeSO ４ After thoroughly purging the polymer chamber with nitrogen gas to 0.007 parts, the internal temperature was set to 80°C. 0.04 parts of sodium sulfoxylate / formaldehyde were added as a 5% aqueous solution, and 0.02 parts of t-butyl hydroperoxide were added. Subsequently, a mixture of 7.76 parts of MMA, 0.24 parts of BA, 0.04 parts of AlMA, and 0.0711 parts of n-OM was continuously added over 24 minutes. 15 minutes after the completion of the addition, 0.0270 parts of t-butyl hydroperoxide were added, and polymerization was continued for another 15 minutes to obtain the polymer (core). The polymerization conversion rate was 97%.

[0115] Subsequently, 0.0045 parts of sodium hydroxide in a 2% aqueous solution was added, followed by 0.08 parts of potassium persulfate in a 2% aqueous solution, and 0.0765 parts of polyoxyethylene lauryl ether sodium phosphate in a 24% aqueous solution. Next, 69 parts of a monomer mixture containing 79.3% BA and 20.7% St, along with 0.345 parts of AlMA and 0.586 parts of TPGDA, were continuously added over 210 minutes. At 40, 80, 120, and 160 minutes from the start of addition, 0.09 parts of polyoxyethylene lauryl ether sodium phosphate in a 24% aqueous solution were added. After the addition of the monomer mixture was completed, 0.021 parts of potassium persulfate in a 2% aqueous solution was added, followed by 0.09 parts of polyoxyethylene lauryl ether sodium phosphate, and 0.0045 parts of sodium hydroxide in a 2% aqueous solution. Polymerization was then continued for a further 90 minutes to obtain latex particles containing a core and a rubber layer. The polymerization conversion rate was 97%, and the average particle size was 166 nm. Subsequently, 0.023 parts of potassium persulfate were added in a 2% aqueous solution, and 0.0402 parts of polyoxyethylene lauryl ether sodium phosphate were added in a 24% aqueous solution. Furthermore, a mixture of 21.85 parts of MMA, 1.15 parts of BA, and 0.05 parts of n-OM was continuously added over 70 minutes, and 0.04 parts of polyoxyethylene lauryl ether sodium phosphate were added 20, 40, and 60 minutes after the start of addition. Polymerization was then continued for 60 minutes to obtain polymer particles having a core and a shell layer. The polymerization conversion rate was 100%. The obtained latex was salted out with calcium chloride, coagulated, washed with water, and dried to obtain white powdery polymer particles.

[0116] (Manufacturing Example 2) <Manufacturing of Polymer Particles> The following substances were charged into an 8L polymerization apparatus with a stirrer: Deionized water 130 parts (by weight; the same applies below) Sodium polyoxyethylene lauryl ether phosphate 0.03 parts Sodium carbonate 0.04725 parts EDTA / FeSO ４After thoroughly purging the polymer chamber with nitrogen gas (0.007 parts), the internal temperature was set to 80°C. 0.04 parts of sodium sulfoxylate / formaldehyde were added as a 5% aqueous solution, and 0.02 parts of t-butyl hydroperoxide were added. Subsequently, a mixture of 12.6 parts of MMA, 0.39 parts of BA, 0.065 parts of AlMA, and 0.1156 parts of n-OM was continuously added over 24 minutes. 20 minutes after the start of addition, 0.09 parts of polyoxyethylene lauryl ether sodium phosphate was added as a 24% aqueous solution. Then, 15 minutes after the end of addition, 0.0270 parts of t-butyl hydroperoxide were added, and polymerization was continued for another 15 minutes to obtain the polymer (core). The polymerization conversion rate was 97%.

[0117] Subsequently, 0.0045 parts of sodium hydroxide in a 2% aqueous solution was added, followed by 0.08 parts of potassium persulfate in a 2% aqueous solution, and 0.0765 parts of polyoxyethylene lauryl ether sodium phosphate in a 24% aqueous solution. Next, 64 parts of a monomer mixture containing 79.3% BA and 20.7% St, 0.32 parts of AlMA, and 1.344 parts of PEG #600DA were continuously added over 190 minutes. 40, 80, and 120 minutes after the start of addition, 0.09 parts of polyoxyethylene lauryl ether sodium phosphate in a 24% aqueous solution were added. After the addition of the monomer mixture was completed, 0.021 parts of potassium persulfate in a 2% aqueous solution, 0.09 parts of polyoxyethylene lauryl ether sodium phosphate, and 0.0045 parts of sodium hydroxide in a 2% aqueous solution were added. Polymerization was then continued for a further 90 minutes to obtain latex particles containing a core and a rubber layer. The polymerization conversion rate was 97%, and the average particle size was 175 nm. Subsequently, 0.023 parts of potassium persulfate were added in a 2% aqueous solution, and 0.0402 parts of polyoxyethylene lauryl ether sodium phosphate were added in a 24% aqueous solution. Furthermore, a mixture of 21.85 parts of MMA, 1.15 parts of BA, and 0.05 parts of n-OM was continuously added over 70 minutes, and 0.04 parts of polyoxyethylene lauryl ether sodium phosphate were added 20, 40, and 60 minutes after the start of addition. Polymerization was then continued for 60 minutes to obtain polymer particles having a core and a shell layer. The polymerization conversion rate was 100%. The obtained latex was salted out with calcium chloride, coagulated, washed with water, and dried to obtain white powdery polymer particles.

[0118] (Production Examples 3-5) Polymerization was carried out in the same manner as in Production Example 1, but with the raw materials changed as shown in Table 1, to obtain white powdery polymer particles.

[0119] (Comparative Manufacturing Example 1) <Production of Polymer Particles> The following substances were charged into an 8L polymerization apparatus with a stirrer: Deionized water 175 parts (by weight; the same applies below) Polyoxyethylene lauryl ether phosphate 0.0104 parts Boric acid 0.4725 parts Sodium carbonate 0.04725 parts EDTA / FeSO ４After thoroughly purging the polymer chamber with 0.007 parts nitrogen gas, the internal temperature was raised to 80°C. 0.04 parts of sodium sulfoxylate / formaldehyde were added as a 5% aqueous solution, and 0.02 parts of t-butyl hydroperoxide were added. Then, a mixture of 6.79 parts of MMA, 0.21 parts of BA, 0.035 parts of AlMA, 0.0259 parts of t-DM, and 0.03 parts of t-butyl hydroperoxide was added all at once. After 2 minutes, 0.0645 parts of sodium sulfoxylate / formaldehyde were added as a 5% aqueous solution. After 15 minutes, 0.05 parts of t-butyl hydroperoxide were added, and polymerization was continued for another 15 minutes. Subsequently, 0.00975 parts of sodium hydroxide were added in a 2% aqueous solution, followed by the continuous addition of a mixture of 19.4 parts of MMA, 0.6 parts of BA, 0.1 parts of AlMA, and 0.0852 parts of polyoxyethylene lauryl ether phosphate over 60 minutes. Thirty minutes after the end of the addition, 0.1 parts of t-butyl hydroperoxide were added, and polymerization was continued for another 30 minutes to obtain the polymer (core). The polymerization conversion rate was 97%.

[0120] Subsequently, 0.0263 parts of sodium hydroxide in a 2% aqueous solution was added, 0.08 parts of potassium persulfate in a 2% aqueous solution was added, and 0.0765 parts of polyoxyethylene lauryl ether sodium phosphate in a 24% aqueous solution was added. Next, a mixture of 50 parts monomer mixture containing 82.0% BA and 18.0% St, 0.75 parts of AlMA, and 0.2328 parts of polyoxylauryl ether phosphate was continuously added over 150 minutes. After the addition of the monomer mixture was completed, 0.015 parts of potassium persulfate in a 2% aqueous solution was added. Polymerization was then continued for another 90 minutes to obtain latex particles containing a core and a rubber layer. The polymerization conversion rate was 97%, and the average particle size was 230 nm. Subsequently, 0.023 parts of potassium persulfate in a 2% aqueous solution was added, and then a mixture of 14.25 parts MMA and 0.75 parts BA was continuously added over 45 minutes. After the addition was complete, polymerization was continued for 30 minutes, and then a mixture of 4.16 parts MMA and 3.84 parts BA was continuously added over 25 minutes. Polymerization was then continued for 60 minutes to obtain polymer particles having a core and a shell layer. The polymerization conversion rate was 100%. The obtained latex was salted out with calcium chloride, coagulated, washed with water, and dried to obtain white powdery polymer particles.

[0121] (Comparative Production Examples 2-3) Polymerization was carried out in the same manner as in Comparative Production Example 1, but with the raw materials changed as shown in Table 1, to obtain white powdery polymer particles.

[0122] (Examples 1-5 and Comparative Examples 1-3) Resin compositions produced using the polymer particles obtained in Production Examples 1-5 and Comparative Examples 1-3 are designated as Examples 1-5 and Comparative Examples 1-3, respectively. <Preparation of Molded Articles> The polymer particles obtained in Production Examples 1-5 or Comparative Examples 1-3 were extruded and kneaded with the acrylic resin Sumipex MH5 (manufactured by Sumitomo Chemical Co., Ltd.) in a ratio of polymer particles / Sumipex MH5 = 30 / 70 using a 40 mm single-screw extruder (DH40-572, manufactured by Tanabe Plastic Machinery Co., Ltd.) at set temperatures C1-C3 = 210°C, C4 = 220°C, HED = 230°C, DIE = 240°C, screw rotation speed 60 rpm, and discharge rate 15 kg / hr to form pellets.

[0123] The obtained pellets were dried at 90°C for about 3 hours, and then injection molded using an injection molding machine (Si-100-6 type, Toyo Machinery & Metal Co., Ltd.) with cylinder temperatures T4 = 235°C, T3 = 235°C, T2 = 240°C, T1 = 250°C, nozzle temperature = 255°C, and mold temperature = 60°C to obtain a 3 mm thick, 15 cm x 10 cm flat plate sample. The haze value of the obtained flat plate sample was measured at 23°C and 60°C as an indicator of transparency.

[0124] Furthermore, 1 / 4 and 1 / 8 inch test pieces were fabricated using an injection molding machine (Si-100-6S model, Toyo Machinery & Metal Co., Ltd.) and impact resistance tests (Izod and Charpy) were performed.

[0125] (Reference Manufacturing Example) <Production of Polymer Particles> The following substances were charged into an 8L polymerization apparatus equipped with a stirrer: Deionized water 130 parts (by weight; the same applies below) Polyoxyethylene lauryl ether phosphate 0.035 parts Boric acid 0.4725 parts Sodium carbonate 0.04725 parts Sodium hydroxide 0.00865 parts After thoroughly purging the inside of the polymerization apparatus with nitrogen gas, the internal temperature was set to 80°C, and 0.005 parts of sodium persulfate was added as a 2% aqueous solution, followed by the continuous addition of a mixture of 7.78 parts of MMA, 0.32 parts of EA, and 0.0144 parts of AlMA over 24 minutes. Fifteen minutes after the completion of the addition, 0.017 parts of sodium persulfate was added as a 2% aqueous solution, 0.2105 parts of polyoxy lauryl ether phosphate was added as a 5% aqueous solution, and 0.0246 parts of sodium hydroxide was added as a 2% aqueous solution. Next, a mixture of 25.9 parts MMA, 1.1 parts EA, and 0.0144 parts AlMA was continuously added over 81 minutes. After the addition was complete, polymerization was continued for another 30 minutes to obtain the polymer (core). The polymerization conversion rate was 97%.

[0126] Subsequently, 0.0495 parts of sodium persulfate were added in a 2% aqueous solution. Then, a mixture of 45 parts monomers containing 81.9% BA and 18.1% St, 0.667 parts of AlMA, and 0.3213 parts of polyoxylauryl ether phosphate was continuously added over 135 minutes. 60 and 150 minutes after the start of addition, 0.0123 parts of sodium hydroxide were added in a 2% aqueous solution, and after the completion of the addition of the monomer mixture, another 0.0123 parts of sodium hydroxide were added in a 2% aqueous solution. Polymerization was then continued for another 60 minutes to obtain latex particles containing a core and a rubber layer. The polymerization conversion rate was 97%, and the average particle size was 210 nm. Subsequently, 0.02 parts of sodium persulfate were added in a 2% aqueous solution. Furthermore, a mixture of 19.2 parts MMA and 0.8 parts EA was continuously added over 60 minutes. Polymerization was then continued for another 60 minutes to obtain polymer particles having a core and a shell layer. The polymerization conversion rate was 100%. The obtained latex was salted out with calcium chloride, coagulated, washed with water, and dried to obtain white powdery polymer particles.

[0127] (Reference Example) <Preparation of Molded Products> Polymer particles obtained in the reference manufacturing example and the acrylic resin Plexiglas 8N (manufactured by Roehm GmbH) were extruded and mixed in a ratio of polymer particles / Plexiglas 8N = 33 / 67 using a 40 mm single-screw extruder (DH40-572, manufactured by Tanabe Plastic Machinery Co., Ltd.) at set temperatures C1-C3 = 210°C, C4 = 220°C, HED = 230°C, DIE = 240°C, screw rotation speed 60 rpm, and discharge rate 15 kg / hr to form pellets.

[0128] Using the obtained pellets, a 15 cm x 10 cm flat plate sample was obtained using an injection molding machine in the same manner as described above, and the haze value was measured at 23°C and 60°C. Similarly, 1 / 4 and 1 / 8 inch test pieces were prepared and subjected to impact resistance tests. The results are shown in Table 1.

[0129]

[0130] Table 1 shows that Examples 1 to 5 exhibited impact resistance comparable to or better than Comparative Examples 1 and 3 and the Reference Example. While the haze values ​​at 23°C were similar, the haze values ​​at 60°C were significantly lower, indicating that whitening at high temperatures was suppressed. The BA / St ratio in the rubber layer of the polymer particles used in Comparative Examples 1 or 3 was 4.6 or 4.5, which is similar to the BA / St ratio of 4.53 shown in the examples of Patent Documents 1 and 2. The proportion of the rubber layer in the polymer particles of Comparative Example 1 was 50% by weight, which is close to the 47% by weight rubber layer proportion shown in the examples of Patent Documents 1 and 2. The Reference Example reproduces the composition shown in Example 4 of Patent Document 2. Furthermore, Examples 1 to 5 exhibited better impact resistance compared to Comparative Example 2.

Claims

1. A thermoplastic resin composition comprising an acrylic resin and polymer particles, wherein the polymer particles have a core, a rubber layer located outside the core, and a shell layer located outside the rubber layer, the rubber layer is formed from a reaction product of a vinyl monomer (a1) and a crosslinkable monomer (a2), the weight ratio of the rubber layer to the polymer particles is 56 to 70% by weight, the vinyl monomer (a1) comprises a (meth)acrylic acid ester and an aromatic vinyl compound, and the weight ratio of the (meth)acrylic acid ester to the aromatic vinyl compound is 3.4 to 4.

3.

2. The thermoplastic resin composition according to claim 1, wherein the (meth)acrylic acid ester is an alkyl acrylate.

3. The thermoplastic resin composition according to claim 1, wherein the shell layer is composed of a polymer of at least one vinyl monomer selected from the group consisting of (meth)acrylic acid esters, aromatic vinyl compounds, and vinyl cyanide compounds.

4. The thermoplastic resin composition according to claim 1, wherein the average particle size of the rubber layer is 125 to 400 nm.

5. The thermoplastic resin composition according to claim 1, wherein the proportion of polymer particles in the total of the acrylic resin and the polymer particles is 3 to 70% by weight.

6. A molded article obtained by molding a thermoplastic resin composition according to any one of claims 1 to 5.

7. The molded article according to claim 6, which is a light-transmitting member.

8. A modifier for acrylic resins, wherein the modifier is a polymer particle, the polymer particle having a core, a rubber layer located outside the core, and a shell layer located outside the rubber layer, the rubber layer being formed from a reaction product of a vinyl monomer (a1) and a crosslinkable monomer (a2), the weight ratio of the rubber layer to the polymer particle being 56 to 70% by weight, the vinyl monomer (a1) comprising a (meth)acrylic acid ester and an aromatic vinyl compound, and the weight ratio of the (meth)acrylic acid ester to the aromatic vinyl compound being 3.4 to 4.3.

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