JP2017149882A - Polymer fine particle and thermoplastic resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polymer fine particle for impact resistance modifier capable of providing a molded article excellent in impact resistance and transparency and a thermoplastic resin composition by blending the same.SOLUTION: There is provided a polymer fine particle having a core layer (C) and a shell layer (S), the core layer (C) containing polyolefin (A) of 5 to 90 mass% and a polymer other than polyolefin (B) of 10 to 95 mass%. There is provided a thermoplastic resin composition containing the polymer fine particle and a thermoplastic resin. Refraction index of the thermoplastic resin is preferably 1.43 to 1.65.SELECTED DRAWING: None

Description

  The present invention relates to polymer fine particles and a thermoplastic resin composition.

Improving the impact resistance of a resin molded product leads to an expanded use of the molded product and a reduction in the thickness and size of the molded product, which is very useful industrially. In addition, improving the transparency of the molded product has advantages such as the ability to expand applications and good color development during coloring. In particular, transparency is regarded as important for polymethyl methacrylate resin and polycarbonate resin, which are highly transparent resins.
For example, as a technique for improving the impact resistance and low temperature impact resistance of a molded product, a technique using a material in which a rubber polymer and a hard resin are combined has been industrialized. As such a material, an ABS resin (acrylonitrile / Butadiene / styrene resin). However, since the ABS resin contains butadiene having an unsaturated bond in the molecular structure, the weather resistance of the molded product is deteriorated.

AES resin (acrylonitrile-ethylene / α-olefin-styrene resin) may be mentioned as an improvement of the weather resistance defect of ABS resin.
For example, Patent Document 1 discloses a graft copolymer obtained by polymerizing a vinyl monomer mixture in the presence of an ethylene / α-olefin copolymer having a molecular weight of 170,000 to 350,000 as a methacrylic ester. A resin composition mixed with a thermoplastic resin such as a resin is disclosed, and impact resistance, color developability and the like are good.
However, in Patent Document 1, impact resistance including low temperature impact resistance cannot be expressed only by mixing only a graft copolymer containing an ethylene / α-olefin copolymer into a thermoplastic resin. In addition, it is necessary to separately add a graft polymer containing a rubber-like polymer, and there is a disadvantage that it takes cost and labor to prepare two types of graft copolymers.

JP2015-147893A

  The present invention has been made in view of the above circumstances, and polymer fine particles for an impact modifier that gives a molded article excellent in impact resistance and transparency, and a thermoplastic resin composition blended therewith. The purpose is to provide.

As a result of intensive studies, the present inventors have found that by using a low molecular weight polyolefin as a rubber component of an impact modifier, the impact resistance and transparency of a molded product obtained by blending it can be improved. The headline and the present invention were completed.
That is, this invention has the following aspects.

[1] It has a core layer (C) and a shell layer (S), and the core layer (C) contains 5 to 90% by mass of the polyolefin (A) and 10 to 95% by mass of the polymer (B) excluding the polyolefin. Polymer fine particles to be contained.
[2] The polymer fine particles according to [1], wherein the polyolefin (A) has a number average molecular weight of 200 to 10,000.
[3] Polymer fine particles according to [1] or [2], wherein the polyolefin (A) is an ethylene / α-olefin copolymer or an ethylene / α-olefin terpolymer having a polymerizable functional group. .
[4] The polymer fine particle according to any one of [1] to [3], wherein the polyolefin (A) has a viscosity of 0.3 to 1000 Pa · s.
[5] The polymer (B) excluding the polyolefin contains at least one monomer unit selected from the group consisting of (meth) acrylic acid ester monomer units and aromatic vinyl monomer units. The polymer fine particle in any one of [1]-[4].
[6] The polymer fine particles according to any one of [1] to [5], wherein the primary particles have a volume average particle diameter of 0.05 to 2.0 μm.
[7] The polymer fine particles according to any one of [1] to [6], wherein a mass ratio of the core layer (C) to the shell layer (S) is 10/90 to 95/5.
[8] The polymer fine particles according to any one of [1] to [7], wherein the shell layer (S) contains a (meth) acrylate monomer unit.
[9] A thermoplastic resin composition comprising the polymer fine particles according to any one of [1] to [8] and a thermoplastic resin.
[10] The thermoplastic resin composition according to [9], wherein the thermoplastic resin has a refractive index of 1.43 to 1.65.
[11] The thermoplastic resin composition according to [9] or [10], wherein the thermoplastic resin is a methacrylic ester resin.

By using the polymer fine particles of the present invention, a thermoplastic resin composition used for molding a molded article having excellent impact resistance and transparency can be obtained.
By molding the thermoplastic resin composition of the present invention, a molded product having excellent impact resistance and transparency can be obtained.

Hereinafter, the present invention will be described in detail.
[Polymer fine particles]
The polymer fine particles of the present invention have a core layer (C) and a shell layer (S), and the shell layer (S) is formed on the outer layer of the core layer (C).
The mass ratio between the core layer (C) and the shell layer (S) is preferably (C) / (S) = 10/90 to 95/5 because the impact resistance of the resulting molded product can be improved. / (S) = 50/50 to 95/5 is more preferable, and (C) / (S) = 70/30 to 95/5 is still more preferable.

  The refractive index of the polymer fine particles is preferably close to that of the thermoplastic resin which is a matrix resin in order to express the transparency of the thermoplastic resin composition. Specifically, 1.40 to 1.67 are preferable, 1.43 to 1.65 are more preferable, and 1.45 to 1.62 are still more preferable. If the refractive index of the polymer fine particles is within this range, the refractive index with the matrix resin is close, and high transparency can be expressed.

  The volume average particle diameter of the primary particles of the polymer fine particles is preferably 0.05 to 2.0 μm, more preferably 0.05 to 1.0 μm, still more preferably 0.05 to 0.8 μm. Here, the volume average particle diameter is a volume average particle diameter determined by a laser diffraction / scattering method.

[Core layer (C)]
The core layer (C) contains a polyolefin (A) and a polymer (B) excluding the polyolefin (hereinafter sometimes referred to as “polymer (B)”). The form of the core layer (C) may be composed of the polyolefin (A) and the polymer (B), and the polyolefin (A) and the polymer (B) may be complexed or may form a multilayer structure. Good. Further, the polyolefin (A) and the polymer (B) may be chemically bonded.

The core layer (C) contains 5 to 90% by mass of the polyolefin (A) and 10 to 95% by mass of the polymer (B) when the whole of (C) is 100% by mass.
The ratio of the polyolefin (A) to the polymer (B) is preferably (A) 5 to 60% by mass / (B) 40 to 95% by mass, (A) 5 to 50% by mass / (B) 50 to 95% by mass. % Is more preferable, and (A) 5-30 mass% / (B) 70-95 mass% is still more preferable.
If (A) / (B) is in this range, the moldability of the resulting thermoplastic resin composition can be maintained well, and the impact resistance of the resulting molded product can be improved.

[Polyolefin (A)]
200-10,000 are preferable, as for the number average molecular weight of polyolefin (A), 300-8000 are more preferable, and 300-5000 are still more preferable. If the number average molecular weight is within the above range, it can serve as a rubber that absorbs impact, and the impact resistance of the resulting molded product can be improved.

  The viscosity of the polyolefin (A) is preferably 0.3 to 1000 Pa · s, more preferably 0.5 to 200 Pa · s, as measured with a B-type viscometer (rotational speed 1 rpm) at 25 ° C. -50 Pa · s is more preferable. If the viscosity is within the above range, it can serve as a rubber that absorbs impact, and the impact resistance of the resulting molded product can be improved.

Examples of the polyolefin (A) include poly α-olefins such as polyethylene and polypropylene; ethylene / α-olefin copolymers such as ethylene / propylene copolymers; and polymerizations such as ethylene / propylene / diene copolymers (EPDM). And an ethylene / α-olefin terpolymer having a functional group.
Among these, ethylene / α-olefin copolymers such as ethylene / propylene copolymers; ethylene / α-olefin terpolymers having a polymerizable functional group such as ethylene / propylene / diene rubber (EPDM) are preferable. .
The α-olefin is preferably an α-olefin having 3 to 10 carbon atoms, such as propylene and 1-butene, and more preferably propylene, from the viewpoints of handleability and glass transition temperature.

The content of the ethylene unit in the polyolefin (A) is preferably 30 to 70% by mass, and preferably 40 to 60% when the whole of (A) is 100% by mass, from the viewpoint of expressing the transparency of the obtained molded product. The mass% is more preferable.
The content of the diene unit of the polyolefin (A) is preferably 0 to 30% by mass, based on 100% by mass of the total of (A), from the viewpoint of expressing impact resistance of the obtained molded product, and preferably 0 to 20%. The mass% is more preferable.

  Examples of commercially available polyolefin (A) include HC-20, HC-40, HC-600, PX-068, and PX-062 (all manufactured by Mitsui Chemicals, Inc.).

[Polymer excluding polyolefin (B)]
The polymer (B) excluding polyolefin may be a polymer other than polyolefin.
Specifically, it is a polymer containing at least one monomer unit selected from the group consisting of (meth) acrylic acid ester monomer units and aromatic vinyl monomer units.

Examples of the (meth) acrylic acid ester monomer used as the raw material for the (meth) acrylic acid ester monomer unit include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, ( Examples include butyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, phenyl (meth) acrylate, and methoxypolyethylene glycol acrylate.
Examples of the aromatic vinyl monomer that is a raw material for the aromatic vinyl monomer unit include styrene and α-methylstyrene.

The polymer (B) excluding polyolefin may contain other monomer units. Examples of other monomers used as raw materials for other monomer units include, for example, vinyl cyanide monomers such as (meth) acrylonitrile, α-cyanoacrylate, dicyanovinylidene, and fumaronitrile ethyl; (meth) acrylic Examples thereof include carboxyl group-containing monomers such as acid, itaconic acid, crotonic acid, maleic acid and maleic anhydride, and salts thereof.
If necessary, a polyfunctional monomer having two or more polymerizable functional groups may be used as another monomer. Examples of the polyfunctional monomer include allyl (meth) acrylate, ethylene glycol dimethacrylate, 1,3-butylene dimethacrylate, and divinylbenzene.

Among these, the (meth) acrylic acid ester monomer is preferable because the glass transition temperature of the core layer is lowered and the impact resistance of the resulting molded product can be improved even at a low temperature of 0 ° C. or less. More preferred are butyl acid, hexyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate.
Moreover, since the refractive index of a core layer can be improved and the transparency of the obtained molded article can be improved, an aromatic vinyl monomer is preferable and (meth) acrylic acid phenyl, styrene, and (alpha) -methylstyrene are more preferable.
These may be used alone or in combination of two or more.
The use of the polyfunctional monomer is based on the elastic modulus of the core layer (C) and the graft ratio of the core layer (C) and the shell layer (S). Sometimes, 0.1 to 10% by mass is preferable, and 0.5 to 5% by mass is more preferable.

[Shell layer (S)]
The shell layer (S) is a layer forming the outermost layer of the polymer fine particles of the present invention, and has a core layer (C) therein.
Shell layer (S) contains a (meth) acrylic acid ester monomer unit.
Examples of the (meth) acrylic acid ester monomer used as the raw material for the (meth) acrylic acid ester monomer unit include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, ( Examples include butyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, phenyl (meth) acrylate, and methoxypolyethylene glycol acrylate.
In addition to these, monomer units derived from carboxyl group-containing monomers such as (meth) acrylic acid, itaconic acid, crotonic acid, maleic acid, maleic anhydride, and salts thereof; styrene, α-methylstyrene, etc. Monomer units derived from aromatic vinyl monomers; monomer units derived from maleimides such as maleimide and phenylmaleimide; (meth) acrylonitrile, α-cyanoacrylate, dicyanovinylidene, fumaronitrile ethyl, etc. Monomer unit made from a vinyl cyanide monomer of the above; single unit made from (meth) acrylamides such as (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N-isopropyl (meth) acrylamide, etc. A monomer unit may be contained.

Among these, when the polymer fine particles and the thermoplastic resin are kneaded, the polymer fine particles are easily compatible with the thermoplastic resin and more easily dispersed more uniformly in the thermoplastic resin. Methyl acid, ethyl (meth) acrylate, butyl (meth) acrylate, and phenyl (meth) acrylate are preferred.
These may be used alone or in combination of two or more.

[Method for producing polymer fine particles]
As a method for producing the polymer fine particles of the present invention, a known polymerization method (emulsion polymerization method, miniemulsion polymerization method, suspension polymerization method, solution polymerization method, bulk polymerization method) can be used.

[Method for producing core layer (C)]
The core layer (C) can be prepared by a polymerization method that can obtain a dispersion of polymer particles such as emulsion polymerization, miniemulsion polymerization, and suspension polymerization. In addition, a polymer obtained from bulk polymerization or solution polymerization can be prepared as a dispersion obtained by crushing and dispersing in a dispersion medium. Among these, emulsion polymerization, miniemulsion polymerization, and suspension polymerization are preferable, and emulsion polymerization and miniemulsion polymerization are more preferable.

As a method for producing the core layer (C) by emulsion polymerization, for example, after preparing a polyolefin aqueous dispersion in which the polyolefin (A) is previously dispersed in water, the monomer (b) as a raw material for the polymer (B) (b) ) And a polymerization initiator are added by an emulsion polymerization method to obtain the core layer (C).
As a method for dispersing the polyolefin (A) in water, a method using a dispersing device such as a homogenizer such as a high-pressure homogenizer or an ultrasonic homogenizer, an ultra turrax or a homodisper, or melt kneading such as a kneader or a multi-screw extruder. A method of applying a mechanical shearing force to the polyolefin (A) by a method using a method and adding the resultant to an aqueous medium containing a dispersion stabilizer such as an emulsifier is preferable.

As a manufacturing method of the core layer (C) by miniemulsion polymerization, for example, the monomer (b) which is a raw material of the polyolefin (A) and the polymer (B) is mutually dissolved, or the polyolefin (A) and The core layer (C) can be obtained by dispersing and polymerizing a liquid obtained by dispersing any one of the monomers (b) in the remaining one together with a polymerization initiator and an emulsifier.
At this time, as a method for dispersing the solution or dispersion of the polyolefin (A) and the monomer (b) in water, a dispersing device such as a homogenizer such as a high pressure homogenizer or an ultrasonic homogenizer, an ultra turrax or a homodisper is used. And a method using a melt kneading method such as a kneader or a multi-screw extruder to give a mechanical shearing force to the polyolefin (A) and add it to an aqueous medium containing a dispersion stabilizer such as an emulsifier. .

[Method for producing shell layer (S)]
As a method for forming the shell layer (S), emulsion polymerization is preferred. In particular, when a dispersion polymerization method such as emulsion polymerization or miniemulsion polymerization is used to form the core layer (C), the shell layer (S) is also formed with the monomer (b) and, if necessary, an emulsifier and polymerization. Multilayer polymer formation by an emulsion polymerization method is preferably used by dropping an initiator.

[Polymerization aid]
A well-known thing can be used for the polymerization initiator used when manufacturing a core layer (C) and a shell layer (S).
As for the usage-amount of a polymerization initiator, 0.001-10 mass parts is preferable when each of the monomer used for formation of a monomer (b) or a shell layer (S) is 100 mass parts.

Known emulsifiers can be used as the emulsifier.
The amount of the emulsifier added is preferably 0.01 to 10 parts by mass when each of the monomers used for forming the monomer (b) or the shell layer (S) is 100 parts by mass.

In the production of polymer fine particles, a chain transfer agent can be used together with the monomer used for forming the monomer (b) or the shell layer (S) for the purpose of adjusting the molecular weight. A well-known thing can be used as a chain transfer agent.
The addition amount of the chain transfer agent is preferably 0.01 to 5 parts by mass when each of the monomers used for forming the monomer (b) or the shell layer (S) is 100 parts by mass.

[Method for removing polymer fine particles]
As a method of taking out the polymer fine particles from the aqueous dispersion of polymer fine particles obtained by the above method, for example, by pouring the aqueous dispersion of polymer fine particles into (hot) water in which the coagulant is dissolved, Examples include a method of coagulating into a slurry and separating water by filtration or the like (coagulation method); a method of spraying and drying an aqueous dispersion of polymer fine particles in a heated atmosphere (spray drying method).
A well-known thing can be used as a coagulant | flocculant.

[Thermoplastic resin]
The thermoplastic resin used by this invention should just be a well-known thermoplastic resin, for example, a polymethacrylate resin is mentioned. Of these, polymethyl methacrylate resin is preferred.
The refractive index of the thermoplastic resin is preferably 1.43 to 1.65, more preferably 1.46 to 1.60 from the viewpoint that the transparency of the thermoplastic resin composition after blending the polymer fine particles can be maintained high. .

[Thermoplastic resin composition]
The thermoplastic resin composition of the present invention (hereinafter sometimes referred to as “resin composition”) contains the polymer fine particles of the present invention and a thermoplastic resin.
The content of the polymer fine particles in the thermoplastic resin composition is preferably 1 to 50% by mass, and more preferably 5 to 45% by mass, when the total is 100% by mass. If the content of the polymer fine particles is within the above range, the molded article obtained can have both high impact resistance and high transparency.
50-99 mass% is preferable and, as for the content rate of the thermoplastic resin in a thermoplastic resin composition, when the whole is 100 mass%, 55-95 mass% is more preferable. If the content of the thermoplastic resin is in the above range, the molded article obtained can have both high impact resistance and high transparency.

  The thermoplastic resin composition may contain additives (antioxidants, lubricants, processing aids, etc.) as necessary. Content of an additive can be defined in the range which does not impair the physical property of the molded article obtained.

[Method for producing thermoplastic resin composition]
The thermoplastic resin composition is produced by mixing polymer fine particles and a thermoplastic resin. For example, a method of blending powdered polymer fine particles and powdered thermoplastic resin in a mixer, a method of shaking in a bag and mixing by hand; a blend of powdered polymer fine particles / thermoplastic resin The method of making a mixture (powder-like mixture) into resin pellets with an extruder is mentioned.

[Molding]
The molded product of the present invention is molded by a known molding method (injection molding method, press molding method, extrusion molding method, vacuum molding method, blow molding method, etc.) using the above powdery mixture or resin pellets. Can be obtained.

EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited to a following example.
In the following examples, “part” represents part by mass, and “%” represents mass%.

[Production of polymer fine particles]
<Production Example 1; polymer fine particles (P1)>
To 3500 g of water, 56.6 g of an aqueous sodium dodecylbenzenesulfonate solution (active ingredient 16%) was added as an emulsifier and dissolved uniformly to prepare an aqueous emulsifier solution.
Separately, as the polyolefin (A), an ethylene / propylene / diene copolymer “Mitsui EPT” (brand “PX-068”, manufactured by Mitsui Chemicals, Inc., viscosity: 10 Pa · s, number average molecular weight: 920) 120 g (10 parts when the polymer fine particle is 100 parts, 11.2% in the core layer); 934 g (n-butyl acrylate) as the monomer (b) as the raw material of the polymer (B) ( 77.8 parts, 87.5%) and 14 g of allyl methacrylate (1.2 parts, 1.3%); 3.6 g of 2,2′-azobis (isobutyronitrile) as an initiator Weighed and mixed.

The previous emulsifier aqueous solution was added thereto and predispersed at 10,000 rpm × 30 seconds using an ultra turrax. The preliminarily dispersed monomer emulsion was further finely and uniformly dispersed by a high-pressure homogenizer (“Nanovaita C-ES”, manufactured by Yoshida Kikai Kogyo Co., Ltd., 100 MPa) to obtain a monomer emulsion.
The monomer emulsion was put into a 5 L separable flask, and a vertical stirring bar was installed, followed by nitrogen substitution by nitrogen bubbling (100 mL / min, 30 minutes). The internal temperature was raised to 65 ° C., and the core layer was polymerized by holding for 60 minutes while stirring at 200 rpm.

  Subsequently, 0.01 g of iron sulfate heptahydrate, which is a redox initiator, 0.036 g of sodium ethylenediaminetetraacetate and 3.6 g of sodium formaldehyde sulfoxylate are dissolved in 100 g of water, and the whole amount is put into a separable flask. And stirred for 15 minutes. As raw materials for the shell layer (S), 126 g of methyl methacrylate (10.5 parts when the polymer fine particles are taken as 100 parts), 6 g of n-butyl acrylate (0.5 parts), and t- 0.66 g of butyl hydroperoxide was uniformly dissolved and added dropwise over 60 minutes. Finally, it was held for 60 minutes to complete the polymerization, and a latex of polymer fine particles (P1) was obtained.

The volume average particle size of the polymer fine particles (P1) was measured using a laser diffraction / scattering particle size distribution measuring device (LA-960, manufactured by Horiba, Ltd.). The volume average particle diameter was 0.27 μm.
The latex of polymer fine particles (P1) was coagulated by the following method to collect powder.
6.5 parts of calcium acetate was dissolved in 100 parts of the solid content of the polymer fine particles in 1.5 times the amount of water of the obtained latex. The latex of polymer fine particles was slowly added to this calcium acetate aqueous solution while stirring. This was heated to 80 ° C. and stirred for 5 minutes to solidify. The obtained slurry was filtered using a gold width and dried at 80 ° C. overnight to obtain a powder.

[Thermoplastic resin composition]
After 200 g of polymer fine particle powder and 1800 g of polymethyl methacrylate resin (trade name “VHK”, manufactured by Mitsubishi Rayon Co., Ltd.) are thoroughly hand-blended in a plastic bag, a twin-screw extruder (TEM35B, Toshiba Machine) Made by extrusion (cylinder temperature: 250 ° C.) and cut to obtain pellets.
After drying the obtained pellets, a flat test piece 1 (with notch, width 10 mm, length 80 mm) at an injection molding machine (IS-100, manufactured by Toshiba Machine) at a cylinder temperature of 250 ° C. and a mold temperature of 80 ° C. , Thickness 4 mm, remaining width 8 mm) and test piece 2 (width 50 mm, length 100 mm, thickness 2 mm).

[Measurement of impact resistance]
Using the test piece 1, according to JIS K7111, the Charpy impact strength with a notch was measured at the measurement temperature of 23 degreeC and -30 degreeC. A measured value of 1.2 kJ / m ² or more was evaluated as “◯”, and a value less than 1.2 kJ / m ² was evaluated as “x”.

[Measurement of total light transmittance]
Using the test piece 2, the total light transmittance was measured according to JIS K7361-1. For the measurement, HGM-2DP manufactured by Suga Test Instruments Co., Ltd. was used.

<Example 1>
Using the polymer fine particles (P1) obtained in Production Example 1 as the polymer fine particles, test pieces were prepared as described above, and the impact resistance and the total light transmittance were measured. The evaluation results are shown in Table 1.

Abbreviations in Table 1 are as follows.
“PX-068”: ethylene / propylene / diene copolymer (trade name “Mitsui EPT”, manufactured by Mitsui Chemicals, Inc.)
“BA”: n-butyl acrylate “AMA”: allyl methacrylate

  As shown in Table 1, since the polymer fine particles (P1) of Example 1 are rubber of the polymer (B) in which the core layer (C) contains polyolefin and n-butyl acrylate units, The impact properties were very high both at 23 ° C. and −30 ° C. The total light transmittance of the resin composition was also good. Moreover, since the polymer fine particles (P1) do not contain an unsaturated bond such as a butadiene unit in the structure, the weather resistance is also good.

Claims (11)

A core layer (C) and a shell layer (S);
Polymer fine particles in which the core layer (C) contains 5 to 90% by mass of the polyolefin (A) and 10 to 95% by mass of the polymer (B) excluding the polyolefin.   The polymer fine particles according to claim 1, wherein the number average molecular weight of the polyolefin (A) is 200 to 10,000.   The polymer fine particles according to claim 1 or 2, wherein the polyolefin (A) is an ethylene / α-olefin copolymer or an ethylene / α-olefin terpolymer having a polymerizable functional group.   The polymer fine particles according to any one of claims 1 to 3, wherein the polyolefin (A) has a viscosity of 0.3 to 1000 Pa · s.   The polymer (B) excluding the polyolefin contains at least one monomer unit selected from the group consisting of a (meth) acrylate monomer unit and an aromatic vinyl monomer unit. Polymer fine particle of any one of -4.   The polymer fine particles according to any one of claims 1 to 5, wherein the primary particles have a volume average particle diameter of 0.05 to 2.0 µm.   The polymer fine particles according to any one of claims 1 to 6, wherein a mass ratio of the core layer (C) to the shell layer (S) is 10/90 to 95/5.   The polymer fine particles according to any one of claims 1 to 7, wherein the shell layer (S) contains a (meth) acrylic acid ester monomer unit.   A thermoplastic resin composition comprising the polymer fine particles according to claim 1 and a thermoplastic resin.   The thermoplastic resin composition of Claim 9 whose refractive index of the said thermoplastic resin is 1.43-1.65. The thermoplastic resin composition according to claim 9 or 10, wherein the thermoplastic resin is a methacrylic ester resin.