JP3272658B2 - Styrene resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a styrenic resin composition, and more particularly to a styrenic resin composition having characteristics such as low gas generation, low odor, and good thermal stability in processing and molding.

[0002]

BACKGROUND OF THE INVENTION As is well known to those skilled in the art, mixing a rubbery graft copolymer with a styrenic copolymer results in a styrenic resin composition having impact resistance. . This type of resin composition is widely used in injection molding, extrusion molding, vacuum molding, blow molding, thermoforming, etc., but in order to increase the practical value of the styrenic resin composition in practice, the resin is usually oxidized during preparation. Add agents to increase thermal stability. Also,
When processing the resin, free radicals and peroxides are likely to be generated, both of which are the main causes of reactive cleavage. Therefore, when producing a styrene-based resin composition, two kinds of antioxidants are usually added to stabilize free radicals and peroxides, respectively. Generally speaking, hindered phenolic antioxidants are used to stabilize the generation of free radicals in processing. On the other hand, a thioether antioxidant such as distearyl thio dipropionate (DSTDP) or Tris nonyl Phenyl Phosphate (Tris nonyl Phenyl Phosphite)
Phosphorus antioxidants such as ite TNPP) are used to stabilize peroxides. As a result, the thermal stability of the resin is increased. However, since thioether-based antioxidants contain sulfur, excessive use often causes heavy odor during processing or in products. Further, in the case of using phosphorus-based antioxidants, if they are used excessively, gas generation may occur in a large amount during processing, and each has its own drawbacks. Therefore, how to reduce gas generation and odor when processing a resin while maintaining good thermal stability has been a major challenge in the art.

[0003] A main object of the present invention is to provide a styrenic resin composition which has low gas generation and odor in a kind of processing and which has characteristics excellent in thermal stability.

[0004]

According to the present invention, there are provided (1) grafting of a styrene monomer, an acrylonitrile monomer and a monomer copolymerizable therewith in the presence of a diene rubber. Styrene resin 10 composed of 5 to 100% by weight of rubbery graft copolymer (A) obtained by copolymerization and 95 to 0% by weight of styrene copolymer (B)
0 parts by weight and (2) a product (C) obtained by butylating a reaction product of paracresol and dicyclopentadiene.
A styrene monomer and / or an acrylonitrile monomer containing 0.01 to 2 parts by weight and (3) 0.01 to 0.8 part by weight of a phosphorus-based antioxidant (D) and / or a thioether-based antioxidant (E). Total dimer and trimer content of 25,0
00ppm or less, residual styrene monomer content is 2,000pp
m or less, and a styrene-based resin composition characterized by being not more than m.

The total content of dimers or trimers composed of styrene monomers and / or acrylonitrile monomers contained in the styrene resin composition is 25,000 ppm or less, and the residual styrene monomers are 2,000 ppm or less. ADVANTAGE OF THE INVENTION According to this invention, the styrene resin composition which is widely used for various shaping | molding and processing, has little odor, has little gas generation, and has good heat stability is obtained.

The rubbery graft copolymer (A) of the present invention
Is 40 to 90 parts by weight of diene rubber, 50 to 90% by weight of styrene monomer, 10 to 50% by weight of acrylonitrile monomer, 0 to 50% by weight of copolymerizable as needed And a bulk, solution, suspension or emulsion polymerization method using 60 to 10 parts by weight of a monomer mixture composed of various monomers. It may also be obtained by two of these methods. For example, there is an emulsion-bulk or bulk-suspension polymerization method. Relatively good methods are an emulsion polymerization method, a bulk polymerization method and a solution polymerization method, and the emulsion polymerization method is particularly the best.

The rubbery graft copolymer (A) obtained by emulsion polymerization is relatively good. The preparation method is as follows: in the presence of a butadiene rubber emulsion, 50 to 90% by weight of a styrene monomer, 10 to 50% by weight. Graft copolymerization with an acrylonitrile-based monomer of 0% by weight and a copolymerizable monomer of 0 to 50% by weight gives an emulsion of a rubbery graft copolymer (A) having an average particle size of 0.05 to 0.8 μm. Is preferred. In this case, the proportion of the rubbery polymer in the rubbery graft copolymer is usually 15 to 85% by weight, preferably 45 to 80% by weight.

What is contained in the above-mentioned butadiene rubber emulsion is a homopolymer composed of 100 to 60% by weight of a conjugated diene monomer and 0 to 40% by weight of a monounsaturated monomer or a copolymer thereof. . The conjugated diene monomer is represented by the following formula.

[0009]

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Here, R is a hydrogen group (H), a methyl group or a chlorine group. Mono-unsaturated monomers include styrene-based monomers, acrylonitrile-based monomers, methacrylate-based monomers, and acrylate-based monomers.

The above-mentioned butadiene rubber emulsion is present in the form of a butadiene-styrene copolymer, a butadiene-acrylonitrile copolymer, a butadiene-methyl methacrylate copolymer and the like. Further, a polymer having a particle size of 0.05 to 0.8 μm is produced by directly polymerizing with the above-mentioned monomer. Alternatively, it is preliminarily polymerized to form a small rubber emulsion of 0.05 to 0.18 μm, which is then enlarged to a rubber emulsion of 0.2 to 0.8 μm by a conventional rubber enlargement method. The following methods are used for the rubber enlargement method. There are a chemical enlargement method using an organic acid, a metal salt or a polymer coagulant containing a carboxylic acid group, a mechanical enlargement method by mechanical stirring, and a freeze enlargement method. Among them, a polymer flocculant used in the chemical enlargement method is a butyl acrylate-methacrylic acid copolymer or the like.
The rubbery graft copolymer (A) obtained by polymerization by the emulsification method has a unimodal particle size distribution, and has an average particle size of 0.05 to
0.8μm, or 0.05 ~
0.18 μm and 0.2 to 0.8 μm.

On the other hand, as a method for copolymerizing the rubbery graft copolymer (A) by a bulk or solution polymerization method, a diene rubber is dissolved in a monomer mixture and a solvent selected as necessary in advance. The monomer mixture contains 50 to 90% by weight of a styrene monomer, 10 to 50% by weight of an acrylonitrile monomer and 0 to 40% by weight of another copolymerizable monomer. The obtained mixture solution is put into a reaction tank by a pump, mixed uniformly, and graft-polymerized. Depending on the circumstances during the reaction, an appropriate amount of a chain transfer agent, for example, t-dodecylmercaptan, is added to control the molecular weight of the polymer. The reaction tank may have a configuration in which a number of tanks are combined, and a kettle-type reaction tank equipped with a powerful stirrer is particularly preferable.

As the diene rubber, butadiene rubber, isoprene rubber, chloroprene rubber and the like are preferable. Among them, butadiene rubber includes a high cis (Hi-Cis) and a low cis (Low-Cis) type. Cis in high cis type rubber
Typical weight composition of (Cis) / vinyl group (Vinyl) is 94-98%
// 1 to 5%, the remaining composition has a trens type structure. Its Mooney viscosity will be between 20 and 120 and the molecular weight range will be between 100,000 and 800,000. A typical weight composition ratio of cis / vinyl groups in the low cis type rubber is 20 to 40.
% / 1 to 20%, and the remaining composition has a trans structure.
Its Mooney viscosity is between 20 and 120. Other suitable rubber materials are: Acrylonitrile / butadiene rubber, styrene / butadiene rubber or the above rubber mixture. Styrene / butadiene rubber is commonly called SBR. The styrene / butadiene copolymer rubber conforming to the present invention has a polymerization type of di-block (tri-blook) copolymer, tri-block (tri-blook) copolymer, random copolymer (randam) or star type (Star typ).
There is a polymerization type of e). The composition of the styrene / butadiene rubber has a weight ratio in the range of 5 /
From 95 to 80/20, the molecular weight range may be 50,000 to 600,000. Preferred rubbers in the present invention are butadiene rubber and styrene / butadiene rubber, butadiene rubber being most preferred.

The average particle size of the rubbery graft copolymer (A) obtained by the bulk or solution polymerization method is generally 0.6 to 10%.
It is in the range of μm, more preferably in the range of 1.0 to 7.0 μm.

The rubbery graft copolymer (A) of the present invention
The above-mentioned emulsion graft copolymer or bulk (or solution) graft copolymer can be used, respectively, and both can be used in combination. This forms a bimodal or trimodal particle size distribution.

The bimodal shape is as follows. (1) Average particle size of 0.2 to 0.8 μm (emulsified) Average particle size of 0.6 to 10 μm (mass or solution) or (2) Average particle size of 0.05 to 0.18 μm (emulsified) Average particle size of 0.6 to 10 μm (mass or solution).

The trimodal shape is as follows. (3) Average particle size 0.05 to 0.18 μm (emulsified) Average particle size 0.2 to 0.8 μm (emulsified) Average particle size 0.6 to 10 μm (bulk or solution).

Specific examples of the styrene monomer used in the present invention include styrene, α-methylstyrene, p-chloromethylstyrene, pt-butylstyrene, p-methylstyrene, o-chlorostyrene, p-chlorostyrene, 2,5-dichlorostyrene, 3,4-dichlorostyrene, 2,4,6-tribromostyrene, 2,5-dibromostyrene, divinylbenzene and the like, among which styrene or α- Methylstyrene is preferred.

Specific examples of the acrylonitrile monomer used in the present invention include acrylonitrile and α-methacrylonitrile, among which acrylonitrile is preferred.

The monomer copolymerizable with the styrene monomer used in the rubbery graft copolymer (A) in the present invention includes, for example, (meth) acrylic acid ester,
There are maleimide monomers, acrylic acid, methacrylic acid, and maleic anhydride. (Meth) acrylic ester monomers include methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, benzyl methacrylate, hexyl methacrylate, cyclohexyl methacrylate, dodecyl methacrylate, 2-hydroxy methacrylate Ethyl, glycidyl methacrylate, dimethylaminoethyl methacrylate, methyl acrylate,
Examples thereof include butyl acrylate, and among them, methyl methacrylate and butyl acrylate are preferable. The maleimide monomers include maleimide, N-methylmaleimide, N-isopropylmaleimide, N-butylmaleimide, N-hexylmaleimide, N-octylmaleimide, N-dodecylmaleimide, N-cyclohexylmaleimide, N-phenyl Maleimide, N-2,3-dimethylphenylmaleimide, N-2,4-dimethylphenylmaleimide, N-2,3-diethylphenylmaleimide, N-2,4-diethylphenylmaleimide, N-
2,3-dibutylphenylmaleimide, N-2,4-dibutylphenylmaleimide, N-2,6-dimethylphenylmaleimide, N-2,3-dichlorophenylmaleimide, N-2,4-dichlorophenylmaleimide, N-
There are 2,3-dibromophenylmaleimide and N-2,4-dibromophenylmaleimide, among which N-phenylmaleimide is preferred.

The styrene copolymer (B) used in the present invention comprises 80 to 50 parts by weight of a styrene monomer, 20 to 50 parts by weight of an acrylonitrile monomer and optionally used copolymer. It is obtained by copolymerizing 0 to 40 parts by weight of a possible monomer. The above description of the styrene monomer, acrylonitrile monomer and other copolymerizable monomers is the same as that used for the preparation of the rubbery graft copolymer (A). Similarly, as a method for preparing the styrene-based copolymer (B), bulk, solution, suspension or emulsion polymerization may be mentioned, but bulk and solution polymerization are preferred, and the weight average molecular weight range is 60,000 to 400. ,
When the molecular weight is between 000 and 3,000, the number average molecular weight is between 30,000 and 200,000. However, if the molecular weight is too large, there are cases where it is difficult to process the material.

The product obtained by butylation of the reaction product of paracresol and dicyclopentadiene in the styrene resin composition of the present invention (Butylated reaction product of p
-Cresol and dicyclopentadiene) (C) has the following structural formula.

[0023]

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Molecular weight = 500-2,000, n is an integer other than 0.

When a phosphorus-based antioxidant is blended with a styrene-based resin, gas is likely to be generated during processing, and when a thioether-based antioxidant is used, odor is likely to be generated during processing or in a finished product. Thus, when the product (C) is added during the preparation, not only can the use amount of the phosphorus-based and / or thioether-based antioxidant be significantly reduced, but also the defects such as gas and odor which are likely to occur during processing can be effectively improved. can do.

The amount of the substance (C) is 0.01 to 2 parts by weight, preferably 0.02 to 1 part by weight. If the amount is less than 0.01 parts by weight, the thermal stability of the styrene resin composition of the present invention is deteriorated, and the practical value is lost. On the other hand, if the used amount exceeds 2 parts by weight, the cost increases and the economic profit is not met.

The amount of the phosphorus antioxidant (D) and / or the thioether antioxidant (E) used in the resin composition of the present invention is 0.01 to 0.8 parts by weight, preferably 0.02 to 0.6 parts by weight. Representative thioether-based antioxidants (E) are as follows. Distearylthiodipropionate, dipalmitylthiodipropionate, pentaerythritol-tetrakis- (β-dodecylmethyl-thiopropionate), didodecylthioether, ditridecylthioether, ditetradecylthioether and dioctadecylthioether is there. On the other hand, the phosphorus-based antioxidants are phosphite-based or phosphonite-based, and include the following. Tris (nonylphenyl) phosphite, tridecylphosphite, cyclic neopentanetetraylbis (octadecylphosphite), 4,4′-butylidenebis (3-methyl-6-tert-butylphenyl-ditridecylphosphite), Tris (2,4-tert-butylphenyl) phosphite or tetrakis (2,4-tert-butylphenyl) 4,4′-biphenylenediphosphonite,
9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and the like.

When the amount of the phosphorus antioxidant (D) and / or the thioether antioxidant (E) is less than 0.01 part by weight, the thermal stability of the resin may be deteriorated. If the amount of the phosphorus-based antioxidant is more than 0.8 parts by weight, the generation of gas when processing the resin cannot be improved. If the amount of the thioether-based antioxidant (E) exceeds 0.8 parts by weight, the odor of the resin cannot be eliminated.

Since the resin composition of the present invention uses the butylated product (C) in combination with the phosphorus-based antioxidant (D) and / or the thioether-based antioxidant (E), the thermal stability is greatly improved. Not only can it be done, but because the amount of antioxidant used is very small, the effect can be exhibited, so it is possible to eliminate the drawbacks that are easily caused by an excessive amount of antioxidant, for example, a lot of gas generation, odor etc. it can.

In the styrene resin composition of the present invention, the amount of a dimer or trimer composed of a styrene monomer and / or an acrylonitrile monomer is specified. Examples of the dimer include AS, AA and SS, and examples of the trimer include AAA, SSS, A ₂ S and S ₂ A.
Here, A represents an acrylonitrile monomer and S represents a styrene monomer. The total content of dimers and trimers consisting of styrene monomers and / or acrylonitrile monomers in the composition of the present invention is 25,000 ppm or less, but 20,000 p
pm or less is preferred.

The residual styrene monomer in the styrene resin composition of the present invention is at most 2,000 ppm, preferably at most 1,500 ppm. When the content exceeds the above range, the odor of the resin cannot be effectively eliminated.

Other additives can be added to the styrenic resin composition of the present invention, if necessary. For example, chelating agents, plasticizers, processing aids, UV stabilizers, UV absorbers, fillers, reinforcing agents, coloring agents, lubricants, antistatic agents, flame retardants, flame retardant aids, heat stabilizers, thermal discoloration prevention Agents, coupling agents or other additives. The above additives can be added during the polymerization reaction, after the reaction, before coagulation, or at any time during the various steps of extrusion kneading.

The amount of the chelating agent used in the present invention is
0.001 to 2.0% by weight is best. Typical examples include bisbenzoylmethane and sodium salt of ethylenediaminetetraacetic acid.

Typical lubricants include metal soaps such as calcium stearate, magnesium stearate, and lithium stearate, ethylenebisstearylamide, methylenebisstearylamide, palmitic amide, butyl stearate, cetyl stearate, and polypropylene. Glycol monostearate, compounds such as behenic acid, stearic acid, etc., silicone oil, polyethylene wax, ethylene, vinyl acetate wax and the like, the total amount of which is usually based on the rubber-modified styrene resin composition of the present invention. 0.03 to 5.0% by weight. There are also methyl methacrylate-based processing aids for improving extrudability and thermoformability.

By using an ultraviolet absorber and an ultraviolet stabilizer, weather resistance and ultraviolet irradiation resistance of the resin can be enhanced, and discoloration and deterioration of the properties of the resin can be prevented. Examples of the ultraviolet absorber include a benzotriazole-based compound, a diphenylketone-based compound, and a cyanopropene-based compound, but are not limited thereto. It is most effective to use it together with an ultraviolet stabilizer. For example, B
ASF's Uvinul 4050H (0.02-1.0% by weight) / Uninul
There is a use example such as 3035 (0.02 to 1.0% by weight), but it is not limited thereto. The total amount of these substances accounts for 0.02 to 2.0% by weight in the styrenic resin composition of the present invention.

Representative examples of the antistatic agent include low molecular weight compounds such as tertiary amine compounds and quaternary ammonium salt compounds, and polyamide polyethers and 3-chloro-1,2-propylene oxide polymers. Permanent antistatic polymeric materials.

Typical fillers include calcium carbonate, silica, mica and the like. Typical reinforcing agents include glass fiber, carbon fiber, and various whiskers (whisk).
er). Representative colorants include titanium oxide, iron oxide, carbon black, and phthalocyanine blue.

Representative examples of the flame retardant or flame retardant aid include decabromodiphenyl ether, tetrabromobisphenol A, brominated polystyrene oligomer, brominated epoxy resin, hexabromocyclododecane, chlorinated polyethylene, triphenyl phosphate, red Examples include phosphorus, antimony oxide, aluminum hydroxide, magnesium hydroxide, zinc borate, melamine, melamine isocyanurate, silicone powder, polytetrafluoroethylene powder, and expandable graphite.

Representative heat stabilizers include dibutyltin maleate, zeolite-based stabilizers, basic magnesium aluminum hydroxide carbonate and the like. In addition, there is a low molecular weight styrene-maleic anhydride copolymer as a thermal discoloration inhibitor, and the addition amount is usually 0.1 to 1.0% by weight of the rubber-modified styrene resin composition of the present invention.

Representative coupling agents include silane, titanate and zirconate compounds.

In order to modify the styrenic resin composition of the present invention, a polymer additive having a suitably high molecular weight may be used. Examples of the polymer additive include bulk polymerization, solution polymerization, and the like. A rubber-modified styrene resin, such as acrylonitrile-butadiene-styrene resin, or a rubber other than butadiene rubber, such as EPDM, which is produced by a polymerization method using a butadiene rubber produced by a method other than the emulsion polymerization method, such as a bulk suspension polymerization method. -Modified styrene resin such as AES resin and AAS resin made by using styrene or butyl acrylate rubber, maleic anhydride-styrene copolymer, styrene-phenylmaleimide copolymer, styrene-acrylonitrile with phenylmaleimide content exceeding 40% by weight -Phenyl maleimide copolymer, styrene-acrylonitrile A copolymer obtained by imidizing a maleic anhydride copolymer with aniline, a crosslinked rubber which is not subjected to a grafting operation such as acrylonitrile-butadiene rubber, a vinyl chloride resin, a poly (meth) acrylate resin, a polycarbonate resin, a polyamide resin, Butylene terephthalate, styrene-based thermoplastic elastomer, various compatibilizers, and the like. The amount of these polymers is usually 3 to 200 parts by weight per 100 parts by weight of the rubber-modified styrenic resin composition of the present invention.
Parts by weight.

[0042]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In order to explain the present invention in more detail, examples and physical property measurement examples will be described below, but the scope of the present invention is not limited to these examples. However, all the following composition components indicate parts by weight, unless otherwise specified.

<Production Example><Production Example I-1> Rubbery Graft Copolymer (A-1)
The raw materials listed below are pumped into a reactor equipped with a stirrer, a heating device and a raw material supply pipe. Ingredients by weight 1,3-butadiene 95.0 acrylonitrile
5.0 Potassium persulfate solution (1%)
15.0 Sodium pyrophosphate 3.0 Potassium oleate 1.5 Distilled water 140.0 Tert-dodecyl mercaptan 0.2 When the above mixture was reacted at 65 ° C for 12 hours, the conversion was 94%, the solid content was 40%, and the weight average particle size was 40%. A synthetic rubber emulsion of about 0.1 μm is obtained.

A polymer flocculant containing a carboxyl group was prepared with the components separately listed below. Ingredients by weight butyl acrylate 85.0 methacrylic acid 15.0 tert-dodecylmercaptan 0.3 potassium oleate 2.0 sodium dioctyl sulfosuccinate 1.0 cumene hydroperoxide 0.4 sodium formaldehyde-modified sodium sulfoxylate 0.3 distilled water 200.0 This gives a carboxyl group-containing polymeric flocculant with a pH of 6.0 at a conversion of 95%.

Thereafter, 100 parts by weight of a synthetic rubber emulsion (solids) is enlarged using 3 parts by weight of the above-mentioned carboxyl group-containing polymer flocculant (solids). The resulting enlarged rubber emulsion has a pH value of 8.5 and a weight average particle size of about 0.31.
μm.

Finally, the enlarged emulsion is subjected to a graft polymerization reaction with the following composition to produce a rubbery graft copolymer (A-1). Ingredients by weight Inflated rubber emulsion (solid content) 100.0 Styrene 25.0 Acrylonitrile 8.3 Potassium oleate 1.2 Tert-dodecyl mercaptan 0.2 Cumene hydroperoxide 0.5 Ferrous sulfate solution (0.2%) 3.0 Formaldehyde-modified sodium sulfoxylate (10%) 3.0 Sodium ethylenediaminetetraacetate solution (0.25%) 20.0 Distilled water 200.0 The obtained rubbery graft emulsion was washed with calcium chloride (CaC
After coagulation in l ₂ ), the rubbery graft copolymer (A-1) required in the present invention is obtained, having a rubber content of 75% by weight and a weight average particle size of 0.31 μm.

<Production Example I-2> Production of Rubbery Graft Copolymer (A-2) Using the synthetic rubber emulsion obtained in Production Example I-1, a graft polymerization reaction was directly carried out according to the following composition to obtain a rubber. To prepare a graft copolymer (A-2).

Ingredients by weight Synthetic rubber emulsion (solid content) 100.0 Styrene 32.4 Acrylonitrile 12.6 Potassium oleate 1.6 Tert-dodecyl mercaptan 0.27 Cumene hydroperoxide 0.67 Ferrous sulfate solution (0.2%) 4.0 Formaldehyde-modified sodium sulfoxylate solution (10% ) 4.0 Sodium ethylenediaminetetraacetate solution (0.25%) 27.0 Distilled water
200.0 When the rubber graft emulsion obtained by the above-mentioned blending is coagulated with calcium chloride (CaCl ₂ ), the rubbery graft copolymer (A-2) required in the present invention is obtained. The rubber content is 69% by weight, and the weight average particle size is 0.1 μm.

<Production Example I-3> Production of Rubbery Graft Copolymer (A-3) Starting from 0.1 parts by weight of tert-dodecyl mercaptan and 0.07 parts by weight of benzoyl peroxide, 6.6 parts by weight of polybutadiene (Asahi Kasei Corporation) The product name is Asaden
o 55AS) is dissolved in a solution composed of 74.4 parts by weight of styrene, 25.6 parts by weight of acrylonitrile and 30 parts by weight of ethylbenzene to obtain a raw material solution. The feed solution is continuously charged into a 45 liter first reactor. Reaction temperature is 10
At 0 ° C., attach a circulating cooling pipe and a screw stirrer to the reactor. The stirring speed is 300 rpm. After the reaction, the mixture is continuously removed from the first reactor and sent to a second reactor equipped with the same equipment as the first reactor. When the conversion of the mixture reaches 60%, the mixture is taken out and sent to a devolatilizer to remove unreacted monomers and volatile substances, and then extruded and sized. Rubbery graft copolymer (A-
3) was obtained, and the weight average particle size of the rubber particles was 1.1 μm.
The rubber content amounts to 11% by weight.

<Production Example II-1> Styrenic copolymer (B
-1) 70% by weight of styrene and 30% by weight of acrylonitrile are mixed in advance, and ethylene bisstearyl amide is mixed at 0.025%.
By weight, the tert-dodecyl mercaptan and the volatile component removed by the reaction as described below are cooled, and the recovered liquid is combined to form a feed liquid. The temperature of the solution is maintained at 145 ° C. and put into a 45-liter continuous kettle reactor equipped with a stirrer.
During the reaction, the methylbenzene ratio in the reaction
% And the conversion is kept at 56%.

After removing volatile components from the reaction solution through a devolatilizer, pellets of a styrene-acrylonitrile copolymer are obtained. On the other hand, the removed volatile components are cooled and condensed into a recovered liquid, which is subsequently used together with the raw material mixture. te
By adjusting the amount of rt-dodecyl mercaptan used, a styrene type (styrene-
Acrylonitrile) copolymer (B-1) is obtained.

<Production Example II-2> Styrene copolymer (B-
Preparation of 2) Raw materials of 70% by weight of styrene and 30% by weight of acrylonitrile are mixed in advance. 0.025% by weight of ethylenebisstearylamide, benzoyl peroxide, tert-dodecylmercaptan, and a liquid obtained by cooling and recovering volatile components removed by the reaction as described below were combined to form a supply liquid. The temperature was maintained at 108 ° C, and a stirrer was attached. To a 45 liter continuous kettle reactor. Keep the amount of methylbenzene in the reaction solution at 15%,
The conversion is kept at 55%.

After the reaction solution is passed through a devolatilizer to remove volatile components, pellets of a styrene-acrylonitrile copolymer are obtained. On the other hand, the removed volatile components are cooled and condensed,
Make a recovery liquid. The recovered liquid is subsequently used together with the raw material mixture described above. In this method, the reaction rate is controlled by the amount of benzoyl peroxide. Alternatively, by adjusting the amount of tert-dodecyl mercaptan, the flow index
Styrene based on 3.0 (styrene-acrylonitrile)
A copolymer (B-2) is obtained.

<Production Example II-3> Styrene copolymer (B-
3) Raw materials of 70% by weight of styrene and 30% by weight of acrylonitrile are mixed in advance. 0.025% by weight of ethylenebisstearylamide, tert-dodecylmercaptan, and a recovered liquid obtained by cooling and recovering volatile components removed by the reaction as described below are used as a feed liquid, and the temperature of the feed liquid is maintained at 155 ° C. Feed into a 45 liter continuous kettle reactor equipped with a stirrer. The amount of methylbenzene in the reaction solution is maintained at 15%, and the polymerization rate is maintained at 57%.

After passing the reaction solution through a devolatilizer to remove volatile components, pellets of a styrene-acrylonitrile copolymer are obtained. On the other hand, the removed volatile components are cooled and recovered, and used together with the raw material mixture as a recovered liquid. tert
By adjusting the amount of dodecyl mercaptan, a styrene (styrene-acrylonitrile) copolymer (B-3) having a melt flow index of 3.35 can be obtained.

<Measurement Method of Physical Properties> The measurement criteria of the physical properties of the resin compositions obtained in Examples of the present invention and Comparative Examples are as follows.

1. Total amount of dimer or trimer made from styrene-based monomer and / or acrylonitrile-based monomer: Hewlett Packard Co., Ltd., obtained by dissolving the resin composition in acetone and attaching a flame ion detector (FID). The resin solution was analyzed using gas chromatography of series number 5890.

2. Residual styrene monomer content: The resin composition was dissolved in acetone, and the resin solution was analyzed using Hewlett Packard series number 5890A gas chromatography equipped with a flame ion detector.

3. Thermal stability: size 4in x 4in x 1/8
A test piece of in (length x width x thickness) is injected, placed in a constant temperature oven at 180 ° C and dried at a constant temperature for 60 minutes, and then the change in color and state (ΔYI) of the test piece is observed. A low ΔYI value indicates that the thermal stability of the resin composition is good.

4. Odor: The obtained styrenic resin composition is extruded with a twin screw extruder, and the gas generated where it is not removed from the die head is evaluated. An evaluation team is formed with three or more people (including three people) to evaluate whether the odor is received continuously for one hour. Appropriate environment for long-term operation is required. If it is accepted as a whole, record as "◎". If you can get it, mark it with "O". If even one person does not feel uncomfortable or smells bad, it is rated "x".

5. The gas generation measurement method is almost the same as when measuring odor. That is,
When it is judged that the gas generation is the least in the whole agreement, it is marked with “◎”, and the next is marked with “○”. When it is evaluated that gas generation is large, it is recorded as “X”.

<Examples><Example1> 35% by weight of the rubbery graft copolymer (A-1) obtained in Production Example I-1 and the styrene-based (styrene / acrylonitrile The monomer weight ratio is
30/70) 100 parts by weight of a styrene resin is composed using 65% by weight of the copolymer (B-1). Further, a product (C) obtained by butylating a reaction product of paracresol and dicyclopentadiene (a product of Goodyear, trade name is Wingsta
yL) and 0.4 parts by weight of tris (nonylphenyl) phosphite (TNPP) are added to make a homogeneous melt. The melt is extruded in a streak shape and then cut into granules. In this resin composition, the total content of the dimer or trimer composed of the styrene monomer and / or the acrylonitrile monomer is 15,000 ppm, and the content of the residual styrene monomer is 1,200 ppm. The composition was evaluated for odor, gas generation and thermal stability, and the results are shown in Table 1.

Example 2 A resin composition was prepared in the same manner as in Example 1, except that the product (C) (obtained by butylating the reaction product of paracresol and dicyclopentadiene) was obtained. Change the amount to 0.3 parts by weight. Table 1 shows the measured physical properties of each item.

Example 3 A resin composition was prepared in the same manner as in Example 1, except that (B-2) obtained in Production Example II-2 was used as a styrene copolymer. The total content of dimers and trimers consisting of styrene monomers and / or acrylonitrile monomers in the obtained resin is 8,200 ppm,
The content of the residual styrene monomer becomes 650 ppm. Table 1 shows the evaluation results of the odor, gas generation, and thermal stability of the composition.

Example 4 A resin composition was prepared in the same manner as in Example 1, except that the product (C) (obtained by butylation of a reaction product of paracresol and dicyclopentadiene) was obtained. The addition amount was changed to 0.1 part by weight, and 0.3 part by weight of IRGANOX-1076 [octadecyl (3,5-di-tert-
Butyl-4-hydroxy-phenyl) propionate]
Is added. Table 1 shows the measured physical properties of each item.

Example 5 A resin composition was prepared in the same manner as in Example 1, except that 0.4 parts by weight of distearyl thiodipropionate (DSTDP) was added instead of tris (nonylphenyl) phosphite. I do. Table 1 shows the results of the measured physical properties and the like.

Example 6 A resin composition was prepared in the same manner as in Example 1, except that the rubber-like graft copolymer (A-2) obtained in Production Example I-2 was used at 38% by weight. By using 62% by weight of the styrenic copolymer (B-1) obtained in Example II-1, 100 parts by weight of a styrenic resin is formed. The total content of the dimer and trimer composed of the styrene monomer and / or acrylonitrile monomer in the obtained resin is 14,400 ppm, and the content of the residual styrene monomer is 1,200 ppm. Similarly, Table 1 shows the evaluation results of the odor, gas generation, and thermal stability of the composition.

Example 7 A resin composition was prepared in the same manner as in the process of Example 1, except that the rubbery graft copolymer was (A-2) obtained in Production Example I-2 at 33% by weight and the production example. By using 30% by weight of (A-3) obtained in I-3 and 37% by weight of styrene-based copolymer (B-1) obtained in Production Example II-1, 100 parts by weight of styrene was obtained. A base resin is formed. For the obtained composition, similarly, measure the total content of dimers and trimers composed of the styrene monomer and / or acrylonitrile monomer, the content of the residual styrene monomer, and various physical properties. The results are shown in Table 1.

Example 8 A resin composition was prepared in the same manner as in Example 1, except that (A-1) obtained in Production Example I-1 was 18% by weight as a rubbery graft copolymer.
15% by weight of (A-2) obtained in Production Example I-2, Production Example I-
(A-3) obtained in Example 3 was used in an amount of 20% by weight, and the styrene copolymer was (B-1) obtained in Production Example II-1 in an amount of 47% by weight.
By using it, 100 parts by weight of a styrene resin is formed. Similarly, regarding the obtained composition, the total content of dimers and trimers composed of the styrene-based monomer and / or acrylonitrile-based monomer, the content of the residual styrene-based monomer, and the physical properties of each item, etc. The measurement was performed and the results are shown in Table 1.

<Comparative Example 1> Raw materials, auxiliary raw materials, etc. were uniformly mixed in the composition shown in Table 1 to obtain a resin composition, physical properties and the like of the product were measured, and odor, gas generation, and thermal stability were obtained. And the results are shown in Table 1.

<Comparative Example 2> As in Comparative Example 1, but 1 part by weight of distearyl thiodipropionate (DSTDP) is added instead of tris (nonylphenyl) phosphite (TNPP). The results are shown in Table 1.

Comparative Example 3 The procedure and conditions were the same as in Example 1, except that the styrene copolymer was changed to that obtained in Production Example II-3 (B-3). The content of the dimer and / or trimer composed of the styrene monomer and / or the acrylonitrile monomer in the composition is 31,000 ppm, and the content of the residual styrene monomer is 2,500 ppm. Become. The results are shown in Table 1.

<Comparative Example 4> A resin composition was obtained by uniformly mixing raw materials and auxiliary raw materials with the composition shown in Table 1, and measuring the physical properties of the product, as well as the odor, gas generation, and thermal stability of the product. Evaluation was performed, and the results are shown in Table 1.

[0074]

[Table 1]

(Note) * 1 Irganox 1076: Octadecyl (3,5-di-tert-
Butyl-4-hydroxyphenyl) propionate * 2 Wingstay-L: product (C) obtained by butylation of the reaction product of paracresol and dicyclopentadiene * 3 TNPP: tris (nonylphenyl) phosphite * 4 DSTDP ： Distearyl thiodipropionate
* 5 SM: Styrene * 6 AN: Acrylonitrile * 7 ΔYI: A test piece made of resin was placed in a thermostat dryer at 180 ° C., and the color changed after 50 minutes.

As can be seen from the experimental results shown in Table 1, 1 part by weight of tris (nonylphenyl) phosphite (D), which is a phosphorus-based antioxidant, was added to styrene-based resin composition.
When used together with 4 parts by weight of Irganox-1076, the measurement result of the odor is good, but the gas generation is clearly increased and the thermal stability (ΔYI) is not good. This is demonstrated by the experimental results of Comparative Example 1. Further, as clearly shown in Comparative Example 2, when 1 part by weight of thioether-based distearyl thiodipropionate and 0.4 part by weight of Irganox-1076 were used in combination as an antioxidant of the styrene-based resin composition, Odors are clearly appearing at the expense of less generation, and
Improvement in thermal stability is insufficient.

Further, as shown in Comparative Example 3, the total content of dimers and trimers composed of a styrene monomer and / or an acrylonitrile monomer contained in the styrene resin composition was 25,000 ppm. When the residual styrene monomer content exceeds 2,000 ppm, the odor and outgassing of the substance are obviously increased. As can be seen from the experimental results of Comparative Example 4, 1.6 parts by weight of the antioxidant DS
When TDP (E) and 0.5 parts by weight of Irganox-1076 were added, the stability of the substance barely reached the level of the present invention. However, since a strong odor was generated and the cost of the antioxidant was high, large addition of , Will not fit the economic return.

On the other hand, as in Examples 1 to 8, the butylated product (C) was converted to a phosphorus-based antioxidant (D) and / or
Or when used in combination with a thioether-based antioxidant (E),
Good thermal stability can be reached with small amounts of antioxidants. Moreover, the disadvantages of severe odor and gassing are alleviated because the amount of antioxidant used is small. Therefore, in the present invention, by controlling the above-mentioned components and the amounts used thereof, it is possible to obtain a styrene-based resin composition which generates less gas during processing, has less odor, and has good thermal stability.

However, since the above-mentioned contents have taken up the embodiments which can be performed relatively well within the present invention, those skilled in the art will cover all modifications or changes using the essential category of the present invention within the scope of the present invention. It is.

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Claims (4)

(57) [Claims] 1. A rubber obtained by graft copolymerizing a styrene monomer, an acrylonitrile monomer and, if necessary, a monomer copolymerizable therewith in the presence of a diene rubber. (2) paracresol and dicyclopentadiene, 100 parts by weight of a styrene resin composed of 5 to 100% by weight of a styrene-based copolymer (A) and 95 to 0% by weight of a styrene-based copolymer (B). 0.01 to 2 parts by weight of a product (C) obtained by butylation of the reaction product and (3) 0.01 to 0.8 part by weight of a phosphorus-based antioxidant (D) and / or a thioether-based antioxidant (E). The total content of dimers and trimers composed of styrene-based monomers and / or acrylonitrile-based monomers is 25,000 ppm or less, and the content of residual styrene-based monomers is 2,000 ppm or less A styrenic resin composition characterized by the above-mentioned. 2. The total content of dimers and trimers comprising a styrene monomer and / or an acrylonitrile monomer is as follows:
The styrenic resin composition according to claim 1, wherein the content is 20,000 ppm or less. 3. The content of the residual styrene monomer is 1,500 p.
3. The styrenic resin composition according to claim 1, wherein the styrenic resin composition is at most pm. 4. The styrenic resin composition according to claim 1, which contains 0.02 to 1 part by weight of the product (C).