JP3163180B2 - Impact resistant resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial applications]

The present invention relates to a resin composition having excellent impact resistance and pigment coloring properties.

[Prior art]

Heretofore, various efforts have been made to enhance the performance of impact resistant resins. For example, JP-A-61-138654
In the publication, attention is paid to the reduction in Tg and elastic modulus of the rubber layer, and the use of polyorganosiloxane rubber having both low Tg and low elastic modulus as a rubber source of impact-resistant resin is studied. However, this method cannot improve the matte-like poor surface appearance derived from the polyorganosiloxane rubber. When such a rubber is used, if the particle diameter is small, the impact resistance is reduced, so that a rubber having a large particle diameter is used.

Japanese Patent Application Laid-Open No. 63-69859 discloses that a vinyl monomer is graft-polymerized on a composite rubber comprising a polyorganosiloxane rubber and a poly (meth) acryl rubber in order to improve the surface appearance of a resin molded product. There has been proposed a composite rubber-based graft copolymer.

[0004]

SUMMARY OF THE INVENTION However, Japanese Patent Application Laid-Open
When the composite rubber-based graft copolymer disclosed in JP 63-69859 is used as the rubber component of the impact-resistant resin, since the particle size of the rubber component is larger than 0.08 μm, coloring when a pigment is added is performed. Poor quality and low industrial value. for that reason,
There has been a strong demand for the development of an impact resistant resin which has good impact resistance and excellent coloring properties when a pigment is added.

[0005]

The inventors of the present invention have conducted intensive studies on the relationship between the particle size of the graft copolymer and the coloring property when a pigment is added. When a composite rubber having a fine particle diameter of a polyorganosiloxane rubber and a poly (meth) acrylate rubber is produced using an organosiloxane rubber, the graft copolymer obtained from the composite rubber exhibits excellent impact resistance. At the same time, they found that they exhibited good pigment coloring properties, and reached the present invention.

That is, the gist of the present invention is to provide a composite rubber comprising a polyorganosiloxane rubber component and an alkyl (meth) acrylate rubber component comprising an alkyl (meth) acrylate and a polyfunctional alkyl (meth) acrylate.
The number average particle diameter obtained by graft polymerization of one or more vinyl monomers is 0.005 to 0.08 μm and 0.10 μm.
and a graft copolymer (A) having a volume of particles larger than 10% by weight of 10% or less of the total particle volume, and an alkyl (meth) acrylate comprising an alkyl (meth) acrylate and a polyfunctional alkyl (meth) acrylate. ) For acrylate rubber,
The number average particle diameter obtained by graft polymerization of one or more vinyl monomers is 0.005 to 0.08 μm and 0.10 μm.
The resin composition comprises 95 to 10% by weight of a graft copolymer (B) in which the volume of particles larger than m is 10% or less of the total particle volume.

[0007] The graft copolymer (A) of the present invention has a number average particle size in the range of 0.005 to 0.08 µm, and moreover 0.10
The volume of the particles larger than μm is 10% or less of the volume of all the graft composite rubber particles. Number average particle size is 0.005
If it is smaller than μm, the impact resistance of a molded product obtained from the resin composition will be deteriorated. On the other hand, when the number average particle size is larger than 0.08 μm, the size of the particles becomes close to the wavelength region of visible light and light scattering by the particles increases, so that the pigment coloring property of the molded product deteriorates.

From the same point, the graft copolymer (B) is
Number average particle diameter is in the range of 0.005 to 0.08 μm, and 0.10
The volume of the particles larger than μm is 10% or less of the volume of all the graft composite rubber particles. Incidentally, the graft copolymers (A) and (B) each had a number average particle diameter of 0.01 to 0.1.
It is preferably in the range of 07 μm.

The polyorganosiloxane rubber used in the present invention is prepared by adding an emulsifier and water to an organosiloxane mixture comprising, for example, a diorganosiloxane, a siloxane-based crosslinking agent and a siloxane-based grafting agent, and then subjecting the mixture to shearing force by high-speed rotation. After obtaining a micronized latex using a homomixer that atomizes, or a homogenizer that atomizes with the jetting power of a high-pressure generator, it is dropped into a high-temperature aqueous solution of dodecylbenzenesulfonic acid at a constant speed and polymerized. It can be obtained by polymerizing for a predetermined time and then neutralizing dodecylbenzenesulfonic acid with an alkaline substance.

The size of the polyorganosiloxane rubber is not particularly limited, but it is preferable that the number average particle diameter is 0.003 to 0.06 μm and the standard deviation of the particle diameter is 0.10 or less. Rubber having such a small size and a narrow particle size distribution is obtained by polymerizing a finely divided latex by dropping it at a very small speed into an aqueous solution of dodecylbenzene sulfonic acid of about 1 to 50% by weight at 50 ° C. or higher. Obtainable. The higher the concentration of the aqueous acid solution, the finer the rubber can be obtained.

Examples of the organosiloxane constituting the organosiloxane mixture include various organosiloxane cyclics having three or more member rings, and those having a three to six member ring are preferred. Specifically, hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, dodecamethylcyclohexasiloxane, trimethyltriphenylcyclotrisiloxane, tetramethyltetraphenylcyclotetrasiloxane, octaphenylcyclotetrasiloxane, etc. These may be used alone or in combination of two or more. These are used in an amount of at least 50% by weight, preferably at least 70% by weight in the organosiloxane-based mixture.

As the siloxane-based crosslinking agent, a trifunctional or tetrafunctional silane-based crosslinking agent such as trimethoxymethylsilane, triethoxyphenylsilane, tetramethoxysilane, tetraethoxysilane, tetra-n-propoxysilane, tetra Butoxysilane or the like is used.
Particularly, a tetrafunctional crosslinking agent is preferable, and among them, tetraethoxysilane is most preferable. The amount of the crosslinking agent to be used is 0 to 30% by weight, preferably 0.5 to 10% by weight in the organosiloxane-based mixture.

As the siloxane-based graft-linking agent, a compound capable of forming a unit represented by the following formula is used.

[0014]

Embedded image

In the above formula, R ¹ represents a methyl group, an ethyl group, a propyl group or a phenyl group, R ² represents a hydrogen atom or a methyl group, n represents 0, 1 or 2, and p represents a number of 1 to 6. .

(Meth) which can form a unit of the formula (I-1)
Acryloyloxysiloxane can form an effective graft chain because of its high grafting efficiency, and is advantageous in terms of exhibiting impact resistance. Note that methacryloyloxysiloxane is particularly preferable as a unit capable of forming the unit of the formula (I-1). Specific examples of methacryloyloxysiloxane include β-methacryloyloxyethyldimethoxymethylsilane, γ-methacryloyloxypropylmethoxydimethylsilane, γ-methacryloyloxypropyldimethoxymethylsilane, γ-methacryloyloxypropyltrimethoxysilane, γ-methacryloyloxypropyl Examples thereof include ethoxydiethylsilane, γ-methacryloyloxypropyldiethoxymethylsilane, and δ-methacryloyloxybutyldiethoxymethylsilane.

Examples of the unit capable of forming the unit of the formula (I-2) include vinylsiloxane, and specific examples include tetramethyltetravinylcyclotetrasiloxane. As a unit capable of forming a unit of the formula (I-3),
p-vinylphenylmethyldimethoxysilane, 2- (p
-Vinylphenyl) ethylmethyldimethoxysilane, 3
-(P-vinylbenzoyloxy) propylmethyldimethoxysilane and the like. As a compound capable of forming the unit of the formula (I-4), γ-mercaptopropyldimethoxymethylsilane, γ-mercaptopropylmethoxydimethylsilane, γ-mercaptopropyldiethoxymethylsilane and the like can be mentioned.

The amount of the grafting agent used in the organosiloxane mixture is not more than 10% by weight, preferably from 0.5 to 5% by weight.

As the emulsifier, an anionic emulsifier is preferable, and an emulsifier selected from sodium alkylbenzene sulfonate, sodium lauryl sulfonate, sodium sulfosuccinate, sodium polyoxyethylene nonylphenyl ether sulfate and the like is used.
Particularly, sulfonic acid emulsifiers such as sodium alkylbenzene sulfonate and sodium lauryl sulfonate are preferable.

These emulsifiers are used in an amount of 0.5 to 30 parts based on 100 parts of the organosiloxane mixture. If the amount is less than 0.5 part, the dispersion state becomes unstable and the emulsified state of a fine particle diameter cannot be maintained. On the other hand, if the amount exceeds 30 parts, the resulting polyorganosiloxane is inconveniently colored due to the emulsifier.

A composite rubber can be obtained by polymerizing the polyorganosiloxane latex thus produced with an alkyl (meth) acrylate component comprising an alkyl (meth) acrylate and a polyfunctional alkyl (meth) acrylate. .

As the alkyl (meth) acrylate,
For example, methyl acrylate, ethyl acrylate, n-
Propyl acrylate, n-butyl acrylate, 2-
Examples thereof include alkyl acrylates such as ethylhexyl acrylate and the like, and alkyl methacrylates such as hexyl methacrylate, 2-ethylhexyl methacrylate and n-lauryl methacrylate. The use of butyl acrylate is preferred.

Examples of the polyfunctional alkyl (meth) acrylate include allyl methacrylate, ethylene glycol dimethacrylate, propylene glycol dimethacrylate, 1,3-butylene glycol dimethacrylate,
Examples include 1,4-butylene glycol dimethacrylate, triallyl cyanurate, triallyl isocyanurate and the like. The amount of the polyfunctional alkyl (meth) acrylate used is 0.1 to 20 in the alkyl (meth) acrylate component.
%, Preferably 0.5 to 10% by weight.

The alkyl (meth) acrylate and the polyfunctional alkyl (meth) acrylate may be used alone or in combination of two or more.

The above-mentioned alkyl (meth) acrylate component is added to the neutralized latex of the polyorganosiloxane rubber component, and is polymerized by the action of a usual radical polymerization initiator. As the polymerization initiator, a peroxide, an azo initiator, or a redox initiator obtained by combining an oxidizing agent and a reducing agent is used. Among these, a redox initiator is preferable, and a sulfoxylate initiator obtained by combining ferrous sulfate, disodium ethylenediaminetetraacetate, Rongalit, and hydroperoxide is particularly preferable.

Polyalkyl (meth) entangled with the crosslinked network of the polyorganosiloxane rubber as the polymerization proceeds
The crosslinked network of the acrylate rubber is further finely formed, and a latex of a composite rubber of a polyorganosiloxane rubber component and a polyalkyl (meth) acrylate rubber component which cannot be separated substantially is obtained.

In the composite rubber of the present invention comprising a polyorganosiloxane rubber and a polyalkyl (meth) acrylate rubber, the content of the polyorganosiloxane rubber component is about 1 to 90% by weight. If the amount is less than 1% by weight, the characteristics of the polyorganosiloxane cannot be exhibited, and the impact resistance decreases. On the other hand, if it exceeds 90% by weight, the gloss derived from the polyorganosiloxane is reduced, and the pigment coloring property is also reduced.

In the practice of the present invention, octamethyltetracyclosiloxane is used as a dialkylorganosiloxane, tetraethoxysilane is used as a siloxane-based crosslinking agent, and γ-methacryloyloxypropyldimethoxymethylsilane is used as a siloxane-based grafting agent. It is preferable to use a composite rubber obtained by compounding a polyalkyl (meth) acrylate rubber component having a main skeleton having a repeating unit of n-butyl acrylate with the obtained polyorganosiloxane rubber.

The composite rubber thus produced by emulsion polymerization can be graft-copolymerized with a vinyl monomer, and can have a polyorganosiloxane rubber component and a polyalkyl (meth) acrylate rubber component. Are strongly entangled with each other, and cannot be separated by extraction with ordinary organic solvents such as acetone and toluene. The gel content of this composite rubber measured by extracting with toluene at 90 ° C. for 12 hours is preferably 80% by weight or more.

Examples of vinyl monomers to be graft-polymerized on the composite rubber include aromatic alkenyl compounds such as styrene, α-methylstyrene and vinyl toluene; methacrylic compounds such as methyl methacrylate and 2-ethylhexyl methacrylate. Acid esters; acrylic esters such as methyl acrylate, ethyl acrylate and butyl acrylate;
Various vinyl monomers such as vinyl cyanide compounds such as acrylonitrile and methacrylonitrile; vinyl compounds containing an epoxy group such as glycidyl methacrylate; vinyl compounds containing a carboxylic acid group such as methacrylic acid; Are used alone or in combination of two or more.

The ratio of the composite rubber to the vinyl monomer when obtaining the graft copolymer of the composite rubber (hereinafter referred to as “graft composite rubber”) is based on the weight of the obtained graft copolymer. It is about 10 to 95% by weight, preferably about 20 to 90% by weight, and about 90 to 5% by weight, preferably about 80 to 10% by weight of a vinyl monomer. If the vinyl monomer is less than 5% by weight, the graft composite rubber component in the resin composition mixed with another resin is not sufficiently dispersed,
On the other hand, if the content exceeds 90% by weight, the impact strength decreases, which is not preferable.

The graft composite rubber can be obtained by adding a vinyl monomer to the latex of the composite rubber and polymerizing it in one step or in multiple steps by a radical polymerization technique.

After the completion of the graft polymerization, the latex is poured into hot water in which a metal salt such as calcium chloride or aluminum sulfate is dissolved, salted out and solidified to separate and recover the graft composite rubber. .

The graft copolymer (B) (hereinafter referred to as "graft acrylic rubber") used in the present invention can be produced by a method similar to that of a conventional graft copolymer.
That is, a crosslinking agent and a graft cross-linking agent are added to an alkyl (meth) acrylate, and a normal radical polymerization initiator is allowed to act thereon to obtain a polyalkyl (meth) acrylate and graft-polymerize a vinyl monomer. Can be manufactured by

As the alkyl (meth) acrylate,
For example, methyl acrylate, ethyl acrylate, n-
Propyl acrylate, n-butyl acrylate, 2-
Alkyl acrylates such as ethylhexyl acrylate
And alkyl methacrylates such as hexyl methacrylate 2-ethylhexyl methacrylate and n-lauryl methacrylate. Use of n-butyl acrylate is particularly preferred.

Examples of the crosslinking agent include allyl methacrylate, ethylene glycol dimethacrylate, propylene glycol dimethacrylate 1,3-butylene glycol dimethacrylate, and 1,4-butylene glycol dimethacrylate. . Also, as a graft crossing agent,
For example, allyl methacrylate, triallyl cyanurate, triallyl isocyanurate and the like can be mentioned.

These cross-linking agents / graft cross-linking agents are used alone or in combination of two or more. The amount of the cross-linking agent and the graft cross-linking agent is from 0.1 to 20% by weight, preferably from 0.5 to 20% by weight in the polyalkyl (meth) acrylate rubber component.
10% by weight.

Examples of the vinyl monomer to be graft-polymerized to the polyalkyl (meth) acrylate rubber include the same ones as in the case of the graft composite rubber. Further, the graft polymerization may be performed in one stage or in multiple stages, and can be separated and recovered in the same manner as in the case of the graft composite rubber.

In the resin composition of the present invention, component (A)
The component (B) can be mixed with the component (B) in a wide range, but is preferably mixed in a range of 5:95 to 90:10 (parts by weight).

The resin composition of the present invention can be obtained by kneading the component (A) and the component (B) with a usual and known kneading machine and extruding. Such machines include mixing rolls, calender rolls, Banbury mixers, extruders, injection molding machines, blow molding machines, inflation molding machines and the like. The resin composition of the present invention may optionally contain a dye, a pigment, a stabilizer, a reinforcing agent, a glass fiber, a filler, a flame retardant, and the like.

Hereinafter, the present invention will be described with reference to examples. In Reference Examples and Examples, “parts” and “%” mean “parts by weight” and “% by weight” unless otherwise specified.

In the reference examples, the particle diameter of the polyorganosiloxane in the latex was measured by a dynamic light scattering method.
This measurement is a method utilizing the fact that particles in the latex have Brownian motion. When the particles in the latex are irradiated with a laser beam, the particles show fluctuations in accordance with the particle diameter. By analyzing this fluctuation, the particle diameter can be calculated. The number average particle size and the standard deviation of the particle size distribution were determined using a DLS-700 model from Otsuka Electronics Co., Ltd.

The degree of swelling and gel content of the polyorganosiloxane were measured by the following method using a polyorganosiloxane obtained by dropping latex into isopropanol, coagulating and drying. That is, the degree of swelling was determined by adding the polyorganosiloxane to toluene at 23 ° C.
It was determined as a value obtained by dividing the weight of toluene absorbed by the polyorganosiloxane when immersed for 8 hours by the weight of the polyorganosiloxane before immersion. The gel content was determined by extracting the polyorganosiloxane in toluene at 23 ° C. for 48 hours.

In the examples, the Izod impact strength is
Measured according to ASTM D 258 (1/4 "notched).
The surface hardness was measured according to ASTM D 785 (Rockwell hardness). Gloss was measured according to ASTM D 523-62 (60 ° specular gloss). The pigment coloring property is JIS Z 8729
(Method of displaying object color using L ^* a ^* b ^* color system).

The number average particle size of the graft composite rubber and 0.10
The volume fraction of particles having a size of μm or more was determined by observing an ultrathin section sample with a transmission electron microscope. This ultra-thin section sample was melt-mixed in an extruder with 90 parts of polymethyl methacrylate and 10 parts of a graft composite rubber, and pelletized.
The pellet was cut out from a press-formed test piece using a microtome.

[0046]

EXAMPLES Reference Example 1 Production of silicone rubber: 2 parts of tetraethoxysilane, 0.5 part of γ-methacryloyloxypropyldimethoxymethylsilane and 97.5 parts of octamethylcyclotetrasiloxane were mixed to give a siloxane-based mixture 1
00 parts were obtained. To this was added 200 parts of distilled water in which 0.67 part of sodium dodecylbenzenesulfonate was dissolved,
After stirring at 10,000 rpm for 2 minutes with a homomixer, the mixture was passed twice through a homogenizer at a pressure of 300 kg / cm ² to obtain a stable premixed organosiloxane latex. Separately, 10 parts of dodecylbenzenesulfonic acid and 190 parts of distilled water were poured into a separable flask equipped with a cooling condenser to prepare a 5% by weight aqueous solution of dodecylbenzenesulfonic acid.

While the aqueous solution was heated to 85 ° C., 300 parts of a premixed organosiloxane latex was added dropwise over 2 hours, and after completion of the addition, the temperature was maintained for 2 hours and the system was cooled. The reaction was then held at room temperature for 12 hours,
Neutralized with aqueous caustic soda.

The thus obtained latex SiLox-
1 was dried at 170 ° C. for 30 minutes and the solid content was determined to be 18.8% by weight. The latex had a swelling degree of 21.8, a gel content of 85.3%, a number average particle diameter of 0.04 μm, and a standard deviation of particle diameter distribution of 0.02 μm.
It was one.

Reference Example 2 Production of graft composite rubber F-1: 53.19 parts of the polyorganosiloxane latex SiLox-1 obtained in Reference Example 1 was collected in a separable flask, and 200 parts of distilled water was added and mixed. Later, 14.70 parts of butyl acrylate, 0.30 of allyl methacrylate
Parts, 0.08 parts of cumene hydroperoxide. The atmosphere in the flask was replaced with nitrogen by passing a nitrogen stream through the separable flask,
The temperature was raised to ° C. When the liquid temperature reaches 60 ° C., an aqueous solution obtained by dissolving 0.003 part of ferrous sulfate, 0.009 part of disodium ethylenediaminetetraacetate and 0.4 part of Rongalite in 10 parts of distilled water is added, and radical polymerization is performed. Started. The liquid temperature rose to 68 ° C. due to the polymerization of the acrylate component. This state was maintained for 1 hour to complete the polymerization of the acrylate component, thereby obtaining a latex of a composite rubber of polyorganosiloxane and butyl acrylate. After the liquid temperature of this latex dropped to 60 ° C., acrylonitrile 1
A mixture of 1.25 parts, 26.25 parts of styrene, and 0.1 part of cumene hydroperoxide was added dropwise over 2 hours to carry out polymerization. After completion of the dropping, the temperature of 60 ° C. was maintained for 1 hour, and then 11.25 parts of acrylonitrile, 26.25 parts of styrene, and 0.03 part of n-octyl mercaptan were again added.
And a mixture of 0.1 part of cumene hydroperoxide was added dropwise over 2 hours to carry out polymerization. After the completion of dropping, temperature 6
After maintaining the temperature of 0 ° C. for 2 hours, the mixture was cooled to complete the graft polymerization of the acrylonitrile / styrene copolymer onto the composite rubber.

The obtained latex of the graft composite rubber was gradually dropped into 200 parts of water (25 ° C.) containing 1.5% by weight of calcium chloride to cause coagulation, followed by solidification by raising the temperature to 90 ° C. The coagulate is then separated from the liquid and, after washing,
After drying at 75 ° C. for 16 hours, 96.4 parts of dry powder of the graft composite rubber F-1 was obtained. The number average particle diameter of this graft composite rubber was 0.06 μm, and the volume fraction of particles larger than 0.10 μm was 4.0%.

Reference Examples 3 and 4 Graft Composite Rubber F-2
And preparation of F-3: graft composite in the same manner as in Reference Example 2 except that the charge composition ratio of latex SiLo-1 and butyl acrylate (BA), allyl methacrylate (AMA) and cumene hydroperoxide was set to the value shown in Table 1. Rubbers F-2 and F-3 were obtained.

Reference Example 5 Production of Graft Acrylic Rubber A-4: Distilled water 2 was placed in a separable flask equipped with a stirrer.
09 parts, sodium dodecylbenzenesulfonate 0.5
Part, and after nitrogen replacement through a nitrogen stream, 60 ° C.
And an aqueous solution obtained by dissolving 0.003 part of ferrous sulfate, 0.009 part of disodium ethylenediaminetetraacetate, and 0.4 part of Rongalite in 10 parts of distilled water when the liquid temperature reaches 60 ° C. Was added. Butyl acrylate 2
4.8 parts, 0.2 parts of allyl methacrylate and 0.1 parts of cumene hydroperoxide were mixed and added dropwise to the aqueous emulsifier solution for 1 hour to initiate radical polymerization. The liquid temperature is 65 by polymerization of butyl acrylate mixed liquid.
To ℃. This state was maintained for one hour to complete the polymerization of butyl acrylate, thereby obtaining an acrylic rubber latex. Then acrylonitrile 11.25
, 26.25 parts of styrene and 0.1 part of cumene hydroperoxide were added dropwise over 2 hours to carry out polymerization. After completion of the dropwise addition, the temperature of 60 ° C. was maintained for 1 hour, and then 11.25 parts of acrylonitrile and 26.25 of styrene again.
, A mixed solution of 0.03 part of n-octyl mercaptan and 0.1 part of cumene hydroperoxide was added dropwise over 2 hours to carry out polymerization. After maintaining the liquid temperature at 60 ° C. for 2 hours, the mixture was cooled to obtain a graft acrylic rubber A-4.

The obtained graft acrylic rubber latex was coagulated, separated, washed and dried in the same manner as in Reference Example 2 to obtain 98.1 parts of a dry powder of the graft acrylic rubber A-4.
The number average particle diameter of this graft rubber is 0.04 μm,
The volume fraction of particles larger than 10 μm was 3.0%.

Examples 1 to 5 and Comparative Examples 1 and 2 The graft rubbers obtained in the Reference Examples were mixed in the proportions shown in Table 2 and further mixed with carbon black (MFC8 manufactured by Mitsubishi Kasei Co., Ltd.).
8) 0.5 parts were mixed. This was supplied to a 25 mmφ extruder, melt-kneaded at 220 ° C., and shaped into pellets. Next, test pieces were manufactured with an injection molding machine (Model IS30 manufactured by Toshiba Machine Co., Ltd.), and the performance was evaluated. The results shown in Table 2 were obtained.

[0055]

[Table 1]

[0056]

[Table 2]

[0057]

The resin composition of the present invention has excellent pigment coloring properties and has excellent impact resistance despite its small particle size.

Continuation of front page (56) References JP-A-4-239010 (JP, A) JP-A-2-199109 (JP, A) JP-A-3-20348 (JP, A) (58) Fields investigated (Int .Cl. ⁷ , DB name) C08L 51/00 C08L 51/08

Claims (1)

(57) [Claims] 1. A composite rubber comprising a polyorganosiloxane rubber component and an alkyl (meth) acrylate rubber component comprising an alkyl (meth) acrylate and a polyfunctional alkyl (meth) acrylate, and one or more vinyl-based monomers. A graft copolymer (A) having a number average particle diameter of 0.005 to 0.08 μm obtained by graft polymerization of the monomer and having a volume of particles larger than 0.10 μm of 10% or less of the total particle volume, 5 to 90% by weight; One or more vinyl monomers are graft-polymerized to an alkyl (meth) acrylate rubber composed of an alkyl (meth) acrylate and a polyfunctional alkyl (meth) acrylate to have a number average particle diameter of 0.005 to 0.08. resin composition comprising 95 to 10% by weight of a graft copolymer (B) in which the volume of particles having a particle size of 0.1 μm and larger than 0.10 μm is 10% or less of the total particle volume