JPH11181214A - Rubber-modified polystyrene-based resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition with excellent impact resistance, in particular, planar impact strength, and high rigidity, by including a rubber- modified polystyrene resin and a specific multilayer graft polymer. SOLUTION: This composition is obtained by including (A) 95.0-99.8 pts.wt. of a polystyrene resin modified with a rubbery polymer (e.g. polybutadiene) and (B) 0.2-5.0 pts.wt. of a multilayer graft polymer 0.05-0.5 μm in average particle size composed of (1) a multilayer-structured core layer with at least one layer consisting of a rubbery polymer <=0 deg.C in glass transition temperature (Tg) (e.g. acrylic rubber) and (2) as the outermost skin layer, a graft polymer made from one or more kinds of vinyl monomer (e.g. styrene).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubber-modified polystyrene resin composition having excellent impact resistance, particularly excellent surface impact strength, and high rigidity.

[0002]

2. Description of the Related Art Rubber-modified polystyrene resins have been widely used as molding materials for household goods, electric appliances and the like because of their excellent moldability and coloring properties and low cost. In these application fields, it is necessary to have a good balance of workability during molding, finished dimensional accuracy of processed products, appearance, mechanical properties such as tension and bending, and various physical properties such as heat resistance. From the viewpoint of materials, it is strongly desired to improve the balance between appearance and impact strength.

In order to improve the appearance and impact strength,
A method of reducing the rubber particle diameter and a method of providing a particle diameter distribution have been proposed. However, in such a method, as a result of improving the appearance, the impact strength is reduced, and in order to improve the impact strength, the appearance is reduced when the rubber particle diameter is increased, and the appearance is reduced when the amount of rubber is increased. There is a limit in various improved methods, such as a decrease in rigidity. In addition, as the impact strength here, Izod impact strength is usually used, but from the viewpoint of exterior materials, further improvement in surface impact strength is required more practically.

However, conventional rubber-modified polystyrene-based resin compositions are not always sufficient to satisfy the above requirements, and these resin compositions are brittlely broken when subjected to a surface impact. To improve this point, there is a method of increasing the rubber component. However, when the rubber component is increased, the rubber-modified polystyrene-based resin composition may be ductilely broken, but the rigidity is greatly reduced. Have a point.

[0005] On the other hand, there is a method for improving impact strength by using a rubber graft polymer obtained by graft-polymerizing one or more vinyl monomers with a rubber polymer as a core on a rubber-modified polystyrene. Proposed. For example, (1) JP-A-61-235462 discloses the use of a rubber-grafted polymer for a rubber-modified polystyrene resin, and (2) JP-A-8-283497 discloses that a rubber-modified polystyrene is used for a rubber-modified polystyrene resin. A combination of a vinyl elastomer and a rubber graft polymer has been proposed.

However, the methods (1) and (2) require a large amount of the rubber graft copolymer in order to obtain a high Izod impact strength. No reduction in rigidity due to this is taken into account. Further, improvement in surface impact strength has not been solved. From this, the problem with the method of increasing the amount of rubber has not been improved. As described above, the method for improving the impact resistance of a rubber-modified polystyrene-based resin composition includes:
Among the many proposals, none of the methods has led to the development of a composition that exhibits sufficient surface impact strength and maintains rigidity.

[0007]

DISCLOSURE OF THE INVENTION The present invention is directed to an impact resistance,
In particular, it is an object of the present invention to provide a rubber-modified polystyrene-based resin composition having both surface impact strength and high rigidity.

[0008]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, by using a specific multilayer graft polymer in a rubber-modified polystyrene resin at a specific composition ratio, the rigidity has been improved. And found that the impact resistance, especially the surface impact strength, can be improved, and the present invention has been completed.

That is, the present invention is as follows. 1) (A) a rubber-modified polystyrene resin modified using a rubber-like polymer, and (B) at least one layer is a rubber-like polymer having a glass transition temperature (Tg) of 0 ° C. or less. One or more multi-layered core layers (b-1);
A polymer having a layer (b-2) in which one or more vinyl monomers have been graft-polymerized as an outermost shell layer,
A multilayer graft polymer having an average particle diameter of 0.05 to 0.5 μm, wherein (A) is 95.0 to 99.8 parts by weight, and (B) is 0.
A rubber-modified polystyrene-based resin composition characterized by being 2 to 5.0 parts by weight.

2) In (B), the vinyl monomer constituting the polymer of the outermost shell layer (b-2) is selected from styrene and an alkyl (meth) acrylate having an alkyl group having 1 to 8 carbon atoms. 2. The rubber-modified polystyrene resin composition according to the above item 1, wherein the composition is a vinyl monomer. 3) The rubber-modified polystyrene resin composition according to 1 or 2 above, wherein the average particle diameter of the rubbery polymer in the rubber-modified polystyrene resin (A) is 0.2 to 4.0 μm.

4) To a total of 100 parts by weight of (A) and (B)
On the other hand, (A) rubbery state in rubber-modified polystyrene resin
When the content of the polymer was X parts by weight and (B) was Y parts by weight,
Wherein X + Y is at least 7 parts by weight.
The rubber-modified polystyrene resin composition according to 1, 2, or 3
Stuff. 5) The flexural modulus of the rubber-modified polystyrene resin composition is
18500Kg / cm ^TwoCharacterized by the above
5. The rubber-modified polystyrene-based tree according to any one of notes 1 to 4.
Fat composition.

Hereinafter, the present invention will be described in detail. In the present invention, the rubber-modified polystyrene resin (A) is a resin in which a rubbery polymer is dispersed in a matrix made of an aromatic vinyl-based polymer in the form of particles. A monomer mixture containing a vinyl monomer and, if necessary, a vinyl monomer copolymerizable therewith is mixed with a known bulk polymerization method, bulk suspension polymerization method, solution polymerization method, or emulsion polymerization method. It is obtained by graft polymerization by a legal method or the like.

Examples of the rubbery polymer mentioned here include polybutadiene (low cis polybutadiene, high cis polybutadiene), styrene-butadiene block copolymer rubber, styrene-butadiene random copolymer rubber, acrylonitrile-butadiene copolymer rubber and the like. Diene rubber and hydrogenation (or partial hydrogenation) of the above diene rubber
Acryl-based rubber such as saturated rubber, isoprene rubber, chloroprene rubber, polybutyl acrylate and ethylene-
Propylene-diene monomer terpolymer (EPDM)
And the like, and a diene rubber is particularly preferable.
From the viewpoint of impact strength and thermal stability, a butadiene-based polymer in which the ratio of cis-1,4 bonds in the butadiene unit chain is 70% by weight or more is more preferable.

The aromatic vinyl monomer as an essential component in the graft polymerizable monomer mixture to be polymerized in the presence of the rubbery polymer includes, for example, styrene, paramethylstyrene, 2,4- Dimethyl styrene, ethyl styrene,
p-tert-butylstyrene, p-chlorostyrene,
p-bromostyrene, nuclear alkyl-substituted styrene such as 2,4,5-tribromostyrene, or α-alkyl-substituted styrene such as α-methylstyrene or α-methyl-p-methylstyrene, with styrene being most preferred. But,
The above-mentioned other aromatic vinyl monomers may be copolymerized mainly with styrene.

[0015] As a component of the rubber-modified polystyrene resin, if necessary, one or more monomer components copolymerizable with an aromatic vinyl monomer can be introduced, and the heat resistance of the resin composition can be further improved. When it is necessary to increase the amount, monomers such as acrylic acid, methacrylic acid, maleic anhydride, and N-substituted maleimide may be copolymerized. The content of the vinyl monomer copolymerizable with the aromatic vinyl monomer as described above,
0 to 40% by weight in the monomer mixture.

In the present invention, the rubber-modified polymer in the rubber-modified polystyrene resin (A) has a rubber particle diameter of 0.2.
To 4.0 μm, more preferably 0.5 to 3.5 μm
Is particularly preferable, and a range of 0.5 to 3.0 μm is particularly preferable. The adjustment of the rubber particle diameter can be performed by a known technique such as controlling the rotation speed of a stirrer attached to the reactor.

The weight of the rubbery polymer in the rubber-modified polystyrene resin (A) is determined by the impact strength of the resin composition,
From the balance of moldability, 2 to 20% by weight, preferably 3% by weight
The range is preferably from 15 to 15% by weight, more preferably from 5 to 13% by weight. In the present invention, the amount of the rubber-modified polystyrene resin (A) can be adjusted by mixing a rubber-modified polystyrene resin obtained by graft polymerization with a polystyrene resin containing no rubber. It is also possible to use a mixture of two or more rubber-modified polystyrene resins. The method of mixing these rubber-modified polystyrene resin and rubber-free polystyrene resin, or a method of mixing two or more rubber-modified polystyrene resins includes a melt kneading method using an extruder, a solvent blending method, and the like. A melt kneading method using a machine is preferred. This mixing can be carried out simultaneously with the operation of mixing (A) the rubber-modified polystyrene resin and (B) the multilayer graft polymer.

In the present invention, the other component (B) is a multilayer graft polymer, wherein at least one layer is a rubbery polymer having a glass transition temperature (Tg) of 0 ° C. or lower. The structural core layer (b-1) is composed of a layer (b-2) obtained by graft-polymerizing one or more vinyl monomers as the outermost shell layer. If the Tg of the rubbery polymer is higher than 0 ° C., sufficient impact resistance cannot be obtained. A more preferred value of Tg is -10C or less.

The multilayer core layer (b-1) is a core layer composed of only one layer of a rubber-like polymer, or a multilayer core layer composed of a layer of a rubber-like polymer and a layer of a non-rubber-like polymer. However, it is essential that at least one layer is a layer made of a rubbery polymer. The weight ratio of the rubber-like polymer layer to the non-rubber-like polymer layer in the multilayer structure core layer (b-1) is such that the ratio of the rubber-like polymer is 100 to 45 parts by weight based on 100 parts by weight of the whole multilayer structure core layer. It is preferred that

The weight ratio of the multilayer core layer (b-1) to the outermost shell layer (b-2), the so-called shell layer, is defined as the ratio of the multilayer core layer to the multilayer graft polymer as 100 parts by weight. Is 10 to 95 parts by weight, preferably 15 to 90 parts by weight.
% By weight is preferred. If it exceeds 95% by weight, the dispersion of the multilayer graft polymer in the resin composition is not sufficient,
If the amount is less than% by weight, the development of impact strength may be insufficient.

The preferred average particle size of the multilayer graft polymer is 0.05 to 0.5 μm. 0.05μm
If it is less than 0.5 μm, the improvement in impact resistance is insufficient.
If the particle diameter exceeds the above range, the appearance of the molded surface will be impaired and the impact resistance will be insufficiently improved. In the present invention, (B)
Examples of the rubbery polymer for the multilayer core layer (b-1) of the multilayer graft polymer include polybutadiene, styrene-butadiene block copolymer rubber, styrene-butadiene random copolymer rubber, and acrylonitrile-butadiene copolymer rubber. , Natural rubber, silicone rubber, acryl-silicon composite rubber and acrylic rubber. Particularly preferred are polybutadiene, styrene-butadiene block copolymer rubber, styrene-butadiene random copolymer rubber, acryl-silicon composite rubber, and acrylic rubber.

In order to form the rubbery polymer, it is preferable to obtain the rubbery polymer by emulsion polymerization. In addition, a crosslinkable monomer can be used for the rubber-like polymer. Examples of these crosslinkable monomers include aromatic divinyls such as divinylbenzene, ethylene glycol diacrylate, ethylene glycol dimethacrylate, butylene glycol diacrylate, hexanediol diacrylate, hexanediol dimethacrylate, and oligoethylene glycol diacrylate. Examples thereof include alkane polyol polyacrylates such as acrylate, oligoethylene glycol dimethacrylate, trimethylolpropane diacrylate, trimethylolpropane dimethacrylate, trimethylolpropane trimethacrylate, and allyl compounds such as alkane polyol polymethacrylate and allyl methacrylate.

The acryl-silicone composite rubber is a crosslinked polyorganosiloxane rubber component 10 comprising a polyorganosiloxane having three or more ring members and a crosslinking agent.
-90% by weight and 90 to 10% by weight of a polyalkyl (meth) acrylate rubber component (the total amount of each rubber component is 100% by weight). Both rubber components were entangled with each other and had a structure that could not be substantially separated. There is a composite rubber.

Examples of the organosiloxane having three or more ring members include linear siloxanes such as dimethylsiloxane, hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, dodecamethylcyclohexasiloxane, and trimethyltriphenylcyclotrisiloxane. Various organosiloxane-based cyclic substances having three or more rings, preferably three to six rings, such as siloxane, tetramethyltetraphenylcyclotetrasiloxane, and octaphenylcyclotetrasiloxane are exemplified. These can be used alone or in combination of two or more. These are used in an amount of 50% by weight or more, preferably 70% by weight or more, in the polyorganosiloxane rubber component.

Examples of the crosslinking agent include trifunctional or tetrafunctional silane crosslinking agents such as trimethoxymethylsilane, triethoxyphenylsilane, tetramethoxysilane, tetraethoxysilane, and tetra-n-propoxysilane. , Tetrabutoxysilane and the like are used.
Particularly, a tetrafunctional crosslinking agent is preferable, and among them, tetraethoxysilane is particularly preferable. The amount of the crosslinking agent used is 0.1 to 30% by weight in the polyorganosiloxane rubber component. If desired, a graft crossing agent can be used, and (meth) acryloyloxysiloxane is particularly preferable. The amount of the graft crossing agent used is 0 to 10% by weight in the polyorganosiloxane rubber component.

The production of the latex of the polyorganosiloxane rubber component is described, for example, in US Pat.
No. 3,294,725, etc. can be used. Further, the polyalkyl (meth) acrylate rubber component can be produced from the following alkyl (meth) acrylate, a crosslinking agent and a graft crosslinking agent. Examples of the alkyl (meth) acrylate include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and n-lauryl ( (Meth) acrylate, and n-butyl acrylate is particularly preferable.
Examples of the crosslinking agent include ethylene glycol dimethacrylate, propylene glycol dimethacrylate,
1,3-butylene glycol dimethacrylate, 1,4
-Butylene glycol dimethacrylate and the like.

Examples of the graft crosslinking agent include allyl methacrylate, triallyl cyanurate, triallyl isocyanurate and the like. Allyl methacrylate can also be used as a crosslinking agent. These crosslinking agents and graft crossing agents are used alone or in combination of two or more. The total amount of the crosslinking agent and the graft crosslinking agent used is 0.1 to 20% by weight based on the polyalkyl (meth) acrylate rubber component.

The polymerization of the polyalkyl (meth) acrylate rubber component is carried out by adding an aqueous solution of an alkali such as sodium hydroxide, potassium hydroxide or sodium carbonate into a latex of the polyorganosiloxane rubber component neutralized.
After adding the above-mentioned alkyl (meth) acrylate, a crosslinking agent and a graft cross-linking agent and impregnating the polyorganosilixane rubber particles, the reaction is carried out by using a usual radical polymerization initiator. When using the above-mentioned acrylic-silicon composite rubber, it is desirable to form it on the innermost layer of the multilayer core layer.

The acrylic rubber of the rubbery polymer includes a polymer obtained by polymerizing a monomer mixture comprising 70 to 90% by weight of n-butyl acrylate and 10 to 30% by weight of an aromatic vinyl compound. No. Examples of the aromatic vinyl compound here include styrene and substituted styrene derivatives, and styrene is preferred.

In the multilayer graft polymer, examples of the non-rubber-like polymer layer in the multilayer core layer (b-1) include, for example, 90 to 99% by weight of methyl methacrylate,
Alkyl acrylate 1 having 1 to 8 carbon atoms in the alkyl group
And a polymer obtained by polymerizing a monomer mixture consisting of 10 to 10% by weight. The carbon number of the above alkyl group is 1 to
Examples of the alkyl acrylate of 8 include methyl acrylate, ethyl acrylate, n-butyl acrylate, and 2-ethylhexyl acrylate, and n-butyl acrylate is preferably used.

Here, in forming the multilayer structure,
In order to enhance the bonding between the polymer layer composed of the rubber-like polymer and the polymer layer composed of the non-rubber-like polymer, the monomer component forming the rubber-like polymer layer and the non-rubber-like polymer layer are combined. A graft-linking monomer copolymerizable with the monomer component can be used. Examples of the graft-binding monomer herein include, for example, allyl, methallyl, or crotyl esters of α, β-unsaturated carboxylic acids, and more specifically, a polyfunctional monomer having a different substituent,
For example, allyl esters of acrylic acid, methacrylic acid, maleic acid, fumaric acid and the like are mentioned, and allyl methacrylate is preferably used. The amount of these graft-linking monomers used is 1.5 to 3.0% by weight based on the total amount of the monomer mixture for forming the rubbery polymer, and the total amount of the monomer mixture for forming the non-rubbery polymer. On the other hand, the range of 0.01 to 0.3% by weight is preferable.

In order to form the above-mentioned multilayer core layer,
Although it is produced by sequential multistage polymerization, it is desirable to use an emulsion polymerization method as a polymerization method. However, it is not particularly limited to this. Next, the vinyl monomer that forms the outermost shell layer (b-2) will be described. As the vinyl monomer, for example, styrene, α-methylstyrene,
o-methylstyrene, m-methylstyrene, p-methylstyrene, ethylstyrene, isobutylstyrene, tertiarybutylstyrene, brominated styrene, aromatic vinyl monomers such as vinyltoluene, dimethylstyrene, vinylnaphthalene, acrylonitrile, methacrylic Vinyl cyanide monomer such as lonitrile, alkyl (meth) acrylate having an alkyl group having 1 to 10 carbon atoms, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate ) Acrylate, 2-ethylhexyl (meth) acrylate, hydroxyethyl (meth) acrylate, cyclohexyl (meth) acrylate, phenyl (meth) acrylate, benzyl (meth) acrylate and the like.

Of these, styrene, α-methylstyrene, acrylonitrile, methacrylonitrile, methyl (meth) acrylate, ethyl (meth) acrylate, and butyl (meth) acrylate are preferred, and styrene, α-methyl is more preferred. Styrene, methyl (meth) acrylate, butyl (meth) acrylate, particularly preferably styrene, methyl (meth) acrylate,
Butyl (meth) acrylate. These are 1
Species or a combination of two or more can be used.

The graft reaction between the above-mentioned multilayered core layer (b-1) and the vinyl monomer constituting the outermost shell layer (b-2) is carried out by a latex of a core polymer having a multilayer structure. By adding a vinyl monomer, polymerization can be carried out in one or more stages by radical polymerization technology. The latex of the multilayer graft polymer obtained by the polymerization is poured into hot water in which a metal salt such as calcium chloride or magnesium sulfide is dissolved, salted out, and coagulated to be separated and recovered.

In the present invention, the composition ratio of the rubber-modified polystyrene resin (A) and the multilayer graft polymer (B) is as follows:
(A) 95.0-99.8 parts by weight, (B) 0.2-5.
0 parts by weight. Preferably (A) 97.0-99.8
Parts by weight, (B) 0.2 to 3.0 parts by weight, more preferably (A) 99.0 to 99.6 parts by weight, (B) 0.4 to 0.4 parts by weight.
1.0 part by weight. If (B) is less than 0.2 parts by weight, the impact resistance is insufficiently improved, and if it exceeds 5.0 parts by weight, the rigidity is reduced.

In the rubber-modified polystyrene resin composition, the rubber-modified polystyrene resin (A) contains 100 parts by weight of the rubber-modified polystyrene resin (A) and the multilayer graft polymer (B) in total. Amount X
X + Y is preferably at least 7 parts by weight, where (B) is Y parts by weight. More preferably, X + Y
Is 10 parts by weight or more. If X + Y is less than 7 parts by weight, the surface impact strength of the rubber-modified polystyrene resin may be low.

A preferred flexural modulus of the rubber-modified polystyrene resin composition of the present invention is a measurement based on ASTM D790, and the 18500Kg / cm ² or more, further preferably 19000Kg / cm ² or more. The method of mixing the rubber-modified polystyrene resin (A) and the multilayer graft polymer (B) includes various known methods, for example, a melt kneading method using an extruder, a solvent blending method, and the like. preferable.

Further, the resin composition of the present invention can be used by adding an antioxidant, a plasticizer, a release agent, a colorant, a flame retardant, an antistatic agent, silicone oil and the like.

[0039]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited by these examples.

[0040]

[Production Example] (Rubber-modified polystyrene resin; A-1) Three reactors equipped with a stirrer are connected in series, and then the rubber-modified polystyrene resin is converted using a polymerization apparatus having a twin-screw extruder with a two-stage vent. Manufactured. It is composed of 78.0 parts by weight of styrene, 12.0 parts by weight of ethylbenzene, 10 parts by weight of polybutadiene rubber (Asaprene 720A, Asahi Chemical Industry Co., Ltd.) and 0.02 parts by weight of 1,1-bis (t-butylperoxy) cyclohexane. The raw material solution was supplied to the reactor to perform polymerization. Polymerization temperature, residence time is 110 ° C-2.5
Time, 125 ° C.-2.5 hours, 150 ° C.-2.5 hours. The polybutadiene content of the obtained rubber-modified polystyrene resin (A-1) was 12.25% by weight, and the rubber particle diameter was 2.5 μm.

(Rubber-modified polystyrene resin; A-2) 78.0 parts by weight of styrene, 12.0 parts by weight of ethylbenzene, 10 parts by weight of polybutadiene rubber (Asaprene 720A, Asahi Kasei Kogyo Co., Ltd.), 1,1-bis (t) A raw material solution comprising 0.02 parts by weight of (-butylperoxy) cyclohexane was supplied to a reactor to carry out polymerization, and a rubber-modified polystyrene resin (A-1) was used, except that the number of stirring in the first reactor was different.
In the same manner as in the case of
-2) was obtained. The obtained rubber-modified polystyrene resin (A
-2) the content of polybutadiene is 12.25% by weight,
The rubber particle size was 0.8 μm.

(Rubber-modified polystyrene resin; A-3) 83.0 parts by weight of styrene, 12.0 parts by weight of ethylbenzene, 5.0 parts by weight of polybutadiene rubber (Asaprene 720A, Asahi Kasei Corporation), The same operation as in the case of the rubber-modified polystyrene resin (A-1) is performed except that the stirring number is different, and
I got The obtained rubber-modified polystyrene resin (A-3)
The polybutadiene content was 6.0% by weight, and the rubber particle diameter was 2.5 μm.

(Rubber-modified polystyrene resin; A-4) 85.0 parts by weight of styrene, 12.0 parts by weight of ethylbenzene, 3.0 parts by weight of polybutadiene rubber (Asaprene 720A, Asahi Kasei Kogyo Co., Ltd.), of the first reactor The same operation as in the case of the rubber-modified polystyrene resin (A-1) was performed except that the stirring number was different, and
I got Obtained rubber modified polystyrene resin (A-4)
Has a polybutadiene content of 4% by weight and a rubber particle diameter of 2.
It was 5 μm.

(Polystyrene resin) Commercially available polystyrene (weight average molecular weight 210,000, number average molecular weight 66,000, no liquid paraffin, manufactured by Asahi Kasei Corporation) was used. (Multilayer graft polymer; B-1) 2 parts by weight of tetraethoxysilane, 0.5 part by weight of γ-methacryloyloxypropyldimethoxysilane and 97.5 parts by weight of octamethylcyclotetrasiloxane were mixed. 100 parts by weight of the above-mentioned mixed siloxane was added to 200 parts by weight of distilled water in which 1 part by weight of sodium dodecylbenzenesulfonate and 1 part by weight of dodecylbenzenesulfonate were dissolved. ^The mixture was emulsified and dispersed at a pressure of ² to obtain an organosilixane latex.

This mixed solution was transferred to a separable flask equipped with a condenser and a stirrer, and mixed while stirring.
After heating at 5 ° C. for 5 hours, the mixture was left at 20 ° C., and after 48 hours, the pH of this latex was adjusted to 7.5 with an aqueous sodium hydroxide solution.
And the polymerization was completed to obtain a crosslinked polyorganosiloxane rubber latex. The polymerization rate of the obtained crosslinked polyorganosiloxane rubber was 88.5%, and the average particle size was 0.16 μm.

119 parts by weight of the above-mentioned crosslinked polyorganosiloxane rubber latex were collected, put into a separable flask equipped with a stirrer, 57.5 parts by weight of distilled water was added, the atmosphere was replaced with nitrogen, and the temperature was raised to 50 ° C. A mixed solution of 33.9 parts by weight of n-butyl acrylate, 1.05 parts by weight of allyl methacrylate and 0.26 parts by weight of tert-butyl hydroperoxide was charged and stirred for 30 minutes, and the mixed solution was permeated into the crosslinked polyorganosiloxane rubber particles. I let it.

Next, a mixture of 0.02 parts by weight of ferrous sulfate, 0.006 parts by weight of sodium ethylenediaminetetraacetate, 0.26 parts by weight of Rongalit and 5 parts by weight of distilled water was charged, and radical polymerization was started. After that, internal temperature 70
C. for 2 hours to complete the polymerization to obtain a composite rubber latex. After 221.5 parts by weight of the composite rubber latex was collected and replaced with nitrogen, the temperature was raised to 60 ° C., and a mixed solution of 0.24 parts by weight of tert-butyl hydroperoxide and 30 parts by weight of methyl methacrylate was added dropwise over 1 hour, Thereafter, the temperature was maintained at 60 ° C. for 2 hours to complete the graft polymerization to the composite rubber.

The obtained graft copolymer latex was dropped into 200 parts by weight of hot water containing 1.5% by weight of calcium chloride, coagulated, separated, washed, and dried at 75 ° C. for 16 hours to obtain a multilayer graft polymer ( A dry powder of B-1) was obtained. The average particle size of this polymer was 0.19 μm. (Multilayer graft polymer; B-2) Metabrene C-201 manufactured by Mitsubishi Rayon Co., Ltd. was used.

(Multilayer graft polymer; B-3) Metablen C-223 manufactured by Mitsubishi Rayon Co., Ltd. was used. (Multilayer graft polymer; B-4) Ion-exchanged water (6860 ml) and sodium dihexylsulfosuccinate (13.7 g) were charged into a 10-liter reactor with reflux cooling and stirred at a rotation speed of 250 rpm in a nitrogen atmosphere. The temperature was raised to 75 ° C. below, so that there was virtually no effect of oxygen. Of a mixture consisting of 1047 g of methyl methacrylate, 67 g of n-butyl acrylate, 0.33 g of 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, and 1.11 g of allyl methacrylate, 22
2 g at a time, and after 5 minutes ammonium persulfate 0.2 g
2 g were added. After 40 minutes, the remaining mixture was
The mixture was continuously added over a period of one minute, and held for another 60 minutes after the completion of the addition.

Next, after adding 1.01 g of ammonium persulfide, 1058 g of butyl acrylate and styrene 2 were added.
A mixture consisting of 28 g, 0.39 g of 2- (2'-hydroxy-5'-methylphenyl) benzotriazole, 27.3 g of allyl methacrylate and 2.5 g of polyethylene glycol diacrylate (molecular weight 200) was mixed with 140
The mixture was continuously added over a period of 1 minute, and after the completion of the addition, the mixture was further maintained for 180 minutes.

Next, after adding 0.30 g of ammonium persulfide, 711 g of methyl methacrylate, 45 g of butyl acrylate, 0.22 g of 2- (2'-hydroxy-5'-methylphenyl) benzotriazole, 0.2 g of n-octyl mercaptan. A mixture consisting of 76 g was continuously added over 40 minutes, and after completion of the addition, the temperature was raised to 95 ° C. and maintained for 30 minutes.

A small amount of the latex thus obtained was sampled, and the average particle diameter was determined by an absorbance method to be 0.26 μm. The remaining latex is poured into a hot aqueous solution of 3% by weight of sodium sulfate for salting out and coagulation.
Next, after repeated dehydration and washing, drying was performed to obtain a multilayer graft polymer (B-4). (Multilayer graft polymer; B-5) 5.7 liters of distilled water in a 10 liter beaker equipped with a stirrer and a condenser, and sodium dioctyl sulfosuccinate 2 as an emulsifier
0 g and Rongalit 1.2 g as a reducing agent were added and uniformly dissolved. Next, 220 g of methyl methacrylate, n
A mixed liquid consisting of 3.0 g of butyl acrylate, 0.8 g of allyl methacrylate and 0.2 g of diisopropylbenzene hydroperoxide was added, polymerized at 80 ° C., and kept for 15 minutes. Then, 1270 g of butyl acrylate,
A mixed solution composed of 320 g of styrene, 20 g of diethylene glycol diacrylate, 13.0 g of allyl methacrylate, and 1.6 g of diisopropylbenzene peroxide was dropped over about 1 hour. It was maintained for about 40 minutes after the completion of the dropping.

Next, 340 g of methyl methacrylate,
2.0 g of butyl acrylate, 0.3 g of diisopropylbenzene peroxide, 0.1 g of n-octyl mercaptan.
A mixture of 1 g was added and held for about 15 minutes. Next, 340 g of methyl methacrylate, 2.0 g of butyl acrylate, 0.1 g of diisopropylbenzene peroxide.
A mixed solution consisting of 3 g and 1.0 g of n-octyl mercaptan was added and maintained for about 15 minutes. Then the temperature was raised to 95 ° C. and held for 1 hour.

A small amount of the latex thus obtained was sampled, and the average particle size was determined by the absorbance method.
It was 12 μm. The remaining latex was poured into a hot water solution of 0.5% by weight of aluminum chloride to carry out salting-out and coagulation, followed by repeated dehydration and washing, followed by drying to obtain a multilayer graft polymer (B-5).

[0055]

Examples 1 to 15 and Comparative Examples 1 to 14 The components prepared according to the above production examples were prepared according to the compositions (unit: parts by weight) shown in Tables 1 and 2 and the cylinder temperature was set to 220 ° C. After kneading and granulating with a screw extruder, a test piece for measuring physical properties was obtained using an injection molding machine (cylinder temperature 200 ° C., mold temperature 50 ° C.). Table 3 shows the results of the evaluation.

In the table, the Izod impact value is ASTM D
The measurement is based on 256 (1/8 inch test piece, notched), and the unit is Kg · cm / cm. 150mm x 150mm as surface impact strength (Dupont impact strength)
Of a 2 mm thick specimen at 25 ° C. and 50% relative humidity
After aging for a period of time, the tip
The 1 kg load weight of the R punch was dropped from a predetermined height, the portion where the impact was applied was observed from the back side, and the presence or absence of breakage was checked. The impact energy was calculated from the maximum height at which no break occurred. The unit is Kg · cm. Flexural modulus is AST
The measurement was performed based on MD790, and the unit was Kg / cm ²
It is.

[0057]

[Table 1]

[0058]

[Table 2]

[0059]

[Table 3]

In Table 3, X and Y are as follows. X: content of rubbery polymer in rubber-modified polystyrene resin (parts by weight) Y: amount of multilayer graft polymer (parts by weight) As is clear from Examples 1 to 15, (A) rubber-modified polystyrene resin and (A) B) When the amount of the multilayer graft polymer is in a specific range, it is understood that a rubber-modified polystyrene resin composition having both high impact resistance, particularly excellent surface impact strength, and high rigidity can be obtained.

[0061]

According to the present invention, it is possible to obtain a rubber-modified polystyrene-based resin composition which has significantly improved impact resistance, especially surface impact strength, and maintains rigidity. Injection molded articles and extrusion molded articles using the composition are useful for applications such as household goods and electric appliances.

Claims (5)

[Claims] 1. A rubber-modified polystyrene resin modified using a rubber-like polymer, and (B) at least one layer is a rubber-like polymer having a glass transition temperature (Tg) of 0 ° C. or lower. One or more multi-layered core layers (b
-1) and a polymer having a layer (b-2) in which one or more vinyl monomers are graft-polymerized as an outermost shell layer, and has an average particle diameter of 0.05 to 0.5 μm. A resin composition comprising a multilayer graft polymer, wherein (A) is 95.0 to 99.8 parts by weight,
(B) 0.2 to 5.0 parts by weight of a rubber-modified polystyrene resin composition. 2. In (B), the vinyl monomer constituting the polymer of the outermost shell layer (b-2) is selected from styrene and an alkyl (meth) acrylate having an alkyl group having 1 to 8 carbon atoms. The rubber-modified polystyrene resin composition according to claim 1, which is a vinyl monomer. 3. The rubber-modified polystyrene resin composition according to claim 1, wherein (A) the rubber-modified polymer in the rubber-modified polystyrene resin has an average particle diameter of 0.2 to 4.0 μm. . 4. When the content of the rubbery polymer in the rubber-modified polystyrene resin (A) is X parts by weight and (B) is Y parts by weight, based on 100 parts by weight of the total of (A) and (B). 4. The rubber-modified polystyrene resin composition according to claim 1, wherein X and Y are at least 7 parts by weight. 5. The rubber-modified polystyrene resin composition according to claim 1, wherein the rubber-modified polystyrene resin composition has a flexural modulus of 18500 Kg / cm ² or more.