JPH10330580A - Thermoplastic resin composition excellent in acetic acid resistance and impact strength - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a thermoplastic resin compsn. which is excellent in resistance to org. chamicals and in impact strength and does not allow cracks to occur in the acetic acid immersion test even when not annealed by compounding a specific ABS resin with specified amts. of a methyl methacrylate (co)polymer and an aliph. polyester. SOLUTION: This compsn. comprises an arom. vinyl-vinyl cyanide copolymer (B), a graft copolymer (A) formed from a rubbery polymer and monomers constituting ingredient B, a methyl methacrylate (co)polymer (C), and an aliph. polyester (D). In the compsn., the concn. of ingredient C is 1-25 wt.%; the concn. of ingredient D is 0.3-10 wt.%; and the ratio of the vinyl cyanide units to the sum of units in ingredients A and B except the rubbery polymer is 25-50 wt.%. Ingredients A and B may be produced by a simultaneous polymn. Ingredient C having an MFR of 15-100 g/10 min is used. ε-Polycaprolactone is esp. pref. as ingredient D. This compsn. is prepd. by melt mixing ingredients A, B, C, and D by a known method.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermoplastic resin composition having excellent resistance to organic chemicals such as acetic acid and impact resistance, and a molded product thereof.

[0002]

2. Description of the Related Art Acrylonitrile-butadiene-styrene copolymer (A) is a kind of resin reinforced with a rubber component.
BS resin) is used in a very wide range of applications such as home appliances, housing equipment, OA equipment, and automotive parts because of its excellent balance of impact resistance and moldability and chemical resistance. . Especially when compared with high impact polystyrene, A
BS resin is superior in chemical resistance, and in applications requiring chemical resistance, ABS resin is often used.

[0003] On the other hand, acetic acid is a chemical having a very high aggressiveness, and cracks are easily generated by immersion under particularly distorted conditions. To judge chemical properties,
It is usually done. As described above, ABS resin is excellent in balance between impact resistance and molding processability and chemical resistance. However, depending on the shape of the injection molded product, cracks are generated by immersion in acetic acid. It has been practiced to prevent the occurrence of cracks by annealing for about several hours.

However, annealing for several hours has problems in terms of economy and productivity, and a material that does not cause cracks in acetic acid immersion without annealing has been required. It is well known that increasing the amount of vinyl cyanide in the ABS component increases the polarity of the resin, thereby improving the chemical resistance, and is disclosed, for example, in JP-B-63-30953. This improves the resistance to organic chemicals, but is not effective in the case of acetic acid.

As described above, in order to obtain a resin composition and a molded product having a molding processability capable of easily injection molding even a complicated shape and having excellent resistance to organic chemicals such as acetic acid at a low price. Was very difficult, but we found that
A homopolymer or copolymer (PMM) obtained by homopolymerizing or copolymerizing a monomer component containing a specific amount of methyl methacrylate as a main component with an ABS resin having a specific composition range.
It has been found that by adding A resin), excellent resistance to acetic acid and organic chemicals can be exhibited without annealing, and the application has been filed (Japanese Patent Application No. 09-116830).
issue).

In this case, however, it is necessary to increase the addition amount of the PMMA resin in order to obtain more excellent acetic acid resistance. If the addition amount is increased, the impact resistance is reduced or the appearance is deteriorated. Or had a problem. On the other hand, the present applicant has already disclosed that the addition of an aliphatic polyester is effective in improving Freon resistance and Sumithion resistance (JP-A-05-339450 and JP-A-07-33933). . Although the resin composition to which the aliphatic polyester is added has a slight effect on the resistance to acetic acid, there is a problem that the effect of improving the resistance to acetic acid is small and the cost is significantly increased as compared with the case where the PMMA resin is added. there were.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a thermoplastic resin composition excellent in acetic acid resistance and impact resistance and a molded article thereof.

[0008]

Means for Solving the Problems As a result of intensive studies on the above problems, the present inventors homopolymerized a monomer component containing a specific amount of methyl methacrylate as a main component with an ABS resin having a specific composition range. Or, by adding a homopolymer or copolymer obtained by copolymerization (PMMA resin) and further adding an aliphatic polyester, it was found that superior resistance to acetic acid and organic chemicals and impact resistance can be exhibited. The present invention has been reached.

That is, the present invention provides: A graft copolymer (I) obtained by copolymerizing a monomer component containing an aromatic vinyl monomer and a vinyl cyanide monomer as main components in the presence of a rubbery polymer, and an aromatic vinyl monomer By homopolymerizing or copolymerizing a copolymer (II) obtained by copolymerizing a monomer component containing a vinyl cyanide monomer as a main component and a monomer component containing methyl methacrylate as a main component. Homopolymer or copolymer (II
A composition comprising I) and an aliphatic polyester (IV), wherein the proportion of (III) in the composition is 1% by weight or more and 25% by weight or less, and the proportion of (IV) is 0.3% by weight.
At least 10% by weight and the proportion of vinyl cyanide in the components other than the rubbery polymer in (I) and (II) is at least 25% by weight and at most 50% by weight. 1. a resin composition; The melt flow rate of a homopolymer or copolymer (III) obtained by homopolymerizing or copolymerizing a monomer component containing methyl methacrylate as a main component (220)
℃, 10kg load) is 15g / 10min or more and 100g /
2. The thermoplastic resin composition according to 1 above, wherein the duration is 10 minutes or less; It is intended to provide a resin molded product obtained by injection molding the thermoplastic resin composition of the above 1 or 2.

Hereinafter, the present invention will be described in more detail. Examples of the rubbery polymer used in (I) of the present invention include polybutadiene, polyisoprene, polyisobutylene, styrene-butadiene random copolymer, styrene-butadiene block copolymer, butadiene-acrylonitrile copolymer, and butadiene- Methacrylonitrile copolymer, butadiene-α, β-unsaturated carboxylic acid alkyl ester copolymer (for example, butadiene-methyl acrylate copolymer, butadiene-ethyl acrylate copolymer, butadiene-butyl acrylate copolymer) , Butadiene-2-ethylhexyl acrylate copolymer, butadiene-methyl methacrylate copolymer, butadiene-ethyl methacrylate copolymer), and hydrogenated products of the diene rubbery polymer. , Acrylic rubber, ethylene-propylene -Saturated rubbery polymers such as diene rubber, fluorine rubber, and silicone rubber, and the like, and these may be used alone or in combination of two or more. Of these, a diene rubber polymer is preferably used, and a butadiene-containing rubber polymer is more preferably used.

These rubbery polymers can be obtained by emulsion polymerization, suspension polymerization or a method of emulsifying the polymer with an emulsifier or the like. The average particle size of the rubbery polymer is preferably in the range of 0.03 to 1.0 μm in order to improve the flow characteristics, surface gloss, impact resistance and chemical resistance of the composition. More preferably, it is 0.08 to 0.5 μm, particularly preferably 0.1 to 0.4 μm. If the average particle size is less than 0.03 μm, impact resistance and chemical resistance are poor.
If it exceeds 1.0 μm, surface gloss and impact resistance are poor.

In the present invention, the graft copolymer (I)
And the monomer component used in the copolymer (II) comprises a vinyl cyanide monomer, an aromatic vinyl monomer, and other copolymerizable monomers. As the vinyl cyanide monomer, acrylonitrile, methacrylonitrile and the like are used. Of these, acrylonitrile is preferred.

As the aromatic vinyl monomer, styrene, α-methylstyrene, halogenated styrene, alkylated styrene, vinylnaphthalene and the like are used, and these can be used as a mixture. Of these, styrene is preferred. In the present invention, in addition to the vinyl cyanide monomer and the aromatic vinyl monomer, other copolymerizable monomers include α, β-unsaturated carboxylic acid alkyl esters, α, β-unsaturated monomers. Carboxylic acids, N-substituted maleimides, maleic anhydride and the like can also be used as needed. Of these, α, β-unsaturated carboxylic acid alkyl esters are preferred. These may be used as a mixture.

Examples of the α, β-unsaturated carboxylic acid alkyl ester include methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, hydroxyethyl acrylate, glycidyl acrylate, and acryl. Cyclohexyl acrylate, phenyl acrylate, benzyl acrylate, methyl methacrylate, 2-ethylhexyl methacrylate, hydroxyethyl methacrylate, glycidyl methacrylate,
Examples include cyclohexyl methacrylate, butylcyclohexyl methacrylate, phenyl methacrylate, and benzyl methacrylate. Among these, ethyl acrylate, propyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, hydroxyethyl acrylate,
Glycidyl methacrylate is preferred.

Examples of the α, β-unsaturated carboxylic acid include acrylic acid and methacrylic acid. Examples of N-substituted maleimides include maleimide, N-methylmaleimide, N-cyclohexylmaleimide, N-
Phenylmaleimide and the like. As a method for producing the graft copolymer (I) and the copolymer (II), a known polymerization method can be used. Examples include methods such as bulk polymerization, suspension polymerization, bulk-suspension polymerization, solution polymerization, and emulsion polymerization.

In general, when the graft copolymer (I) is produced, the copolymer (II) is always produced as a by-product. ) And the copolymer (II) may be produced at the same time, or the polymerization may be carried out with a higher number of rubber parts than the target rubber concentration, and the resulting polymer may be diluted with the copolymer (II) produced separately.

The monomer component used in the homopolymer or copolymer (III) comprises a monomer containing a methyl methacrylate monomer and other copolymerizable monomers. Other copolymerizable monomers include, for example, α, β-unsaturated carboxylic acid alkyl ester, α, β-unsaturated carboxylic acid, aromatic vinyl, vinyl cyanide, N-substituted maleimides, maleic anhydride Examples include acids and the like, which can be used as necessary. Further, the above-mentioned rubbery polymer may be contained. Of these, α, β-unsaturated carboxylic acid alkyl esters are preferred. These may be used as a mixture.

Examples of the α, β-unsaturated alkyl carboxylate include methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, hydroxyethyl acrylate, and the like.
Glycidyl acrylate, cyclohexyl acrylate, phenyl acrylate, benzyl acrylate, 2-ethylhexyl methacrylate, hydroxyethyl methacrylate,
Glycidyl methacrylate, cyclohexyl methacrylate, butylcyclohexyl methacrylate, phenyl methacrylate, benzyl methacrylate and the like can be mentioned. Among these, methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, acrylate 2-
Ethylhexyl and butylcyclohexyl methacrylate are preferred. Examples of the α, β-unsaturated carboxylic acid include acrylic acid and methacrylic acid. Examples of the aromatic vinyl include styrene, α-methylstyrene, halogenated styrene, alkylated styrene, vinylnaphthalene and the like. Examples of vinyl cyanide include acrylonitrile and methacrylonitrile. Examples of the N-substituted maleimides include maleimide, N-methylmaleimide, N-cyclohexylmaleimide, N-phenylmaleimide and the like.

The homopolymer or copolymer (III) can be produced by a known polymerization method. Examples include methods such as bulk polymerization, suspension polymerization, bulk-suspension polymerization, solution polymerization, and emulsion polymerization. Melt flow rate of homopolymer or copolymer (III) (220 ° C, 10
kg load) is preferably 15 g / 10 min or more and 100 g / 10 min or less. More preferably, 15 g / 1
It is 0 minutes or more and 60 g / 10 minutes or less. If the melt flow rate is less than 15 g / 10 minutes, the acetic acid resistance is inferior.
If it exceeds 0 g / 10 min, the molecular weight will be low, and the impact resistance and chemical resistance will be poor, which is not preferable.

Examples of the aliphatic polyester (IV) include polyesters of adipic acid and alkylene glycol such as polycaprolactone, polyenantholactone, polycaprylolactone, polyethylene adipate and polybutylene adipate, and succinic acids and alkylene glycols such as polyethylene succinate. Polyesters with glycols, polyesters with sebacic acid and alkylene glycols such as polybutylene sebasate, polyesters with dicarboxylic acids such as polycyclohexane dimethylene succinate and cyclohexane dimethylene glycol, and the like, and one or more of these. Can be used. Among them, polycaprolactone is preferred.
Particularly, ε-polycaprolactone is preferred. Polycaprolactone may have a part of hydrogen atoms in the methylene chain substituted by a halogen atom or a hydrocarbon group, for example, a methyl group or the like, or may have its terminal terminated by esterification or the like. The molecular weight of the aliphatic polyester (IV) is 2,000 to 500,000, preferably 500
0 to 100,000. As the production method, a known polymerization method can be used. For example, it can be produced by subjecting an aliphatic ester compound such as caprolactone to ring-opening polymerization using a compound having active hydrogen such as alcohol as an initiator in the presence of a catalyst such as an acid, a base or an organometallic compound.

The method of kneading the thus obtained graft copolymer (I), copolymer (II), homopolymer or copolymer (III), and aliphatic polyester (IV) is particularly limited. Not a thing, a known technique, for example,
A method of mixing liquids, powders, and granules with a Henschel mixer, tumbler, blender, etc., and melt-mixing them with an extruder, kneader, mixer, etc., and directly and sequentially mixing other resins and liquids with a pre-melted resin. It can be manufactured by various methods such as a method. The kneading order is not limited. For example, the graft copolymer (I) and the copolymer (I)
I), the homopolymer or copolymer (III), and the aliphatic polyester (IV) may be kneaded all at once, or the graft copolymer (I) and the copolymer (II) may be kneaded first,
A homopolymer or a copolymer (II
I) and the aliphatic polyester (IV) may be kneaded.

The content of the rubbery polymer component in the resin composition thus obtained is not particularly limited in the present invention, but is preferably 5% by weight to 30% by weight in the resin composition. The content is preferably not more than 8% by weight and more preferably not more than 20% by weight. If it is less than 5% by weight, the impact resistance is poor, and if it is more than 30% by weight, the moldability is poor. Further, a homopolymer or a copolymer (II
The proportion of I) needs to be 1% by weight or more and 25% by weight or less, preferably 2% by weight or more and 20% by weight or less,
More preferably, the content is 3% by weight or more and 15% by weight or less. 1
When the amount is less than 25% by weight, there is no effect of improving the chemical resistance. When the amount is more than 25% by weight, the weld is remarkably conspicuous and the appearance is not preferable. The proportion of the aliphatic polyester (IV) needs to be 0.3% by weight or more and 10% by weight or less, preferably 0.5% by weight or more and 7% by weight or less, more preferably 0.5% by weight or less. Not less than 5% by weight.
If it is less than 0.3% by weight, the effect of improving the chemical resistance and impact resistance is small, and if it is more than 10% by weight, the compatibility is inferior, and peeling is caused.

Furthermore, in the graft polymer (I) and the copolymer (II), the proportion of vinyl cyanide in the components other than the rubbery polymer must be 25% by weight or more and 50% by weight or less. , Preferably from 25% by weight to 45% by weight. If the amount is less than 25% by weight, the surface is dissolved in acetic acid, which is not preferable in appearance. 50% by weight
If it is more than this, molding workability and thermal stability are remarkably deteriorated, which is not preferable.

Further, a known heat stabilizer, ultraviolet absorber, light stabilizer, antioxidant,
Plasticizers, release agents, lubricants, antistatic agents, flame retardants, colorants,
Various additives such as an organic filler and an inorganic filler, and a metal such as aluminum and copper are added to impart a metallic appearance, or another resin is added to obtain a stone-like appearance. It is optional.

A sheet obtained by subjecting such a thermoplastic resin composition to injection molding, injection-compression molding, extrusion molding, blow molding, compression molding, calender molding, or extrusion molding is used to form a sheet by vacuum molding, compression molding, compression molding. A desired molded product can be obtained by vacuum molding or the like. In particular, when a molded article is obtained by injection molding, the effect of using the resin of the present invention is enormous. The shape of the molded body is not particularly limited.

[0026]

Next, the present invention will be described in more detail with reference to Examples and Reference Examples. The evaluation method used in the present invention is as follows. Evaluation of chemical resistance (crack) A roof-shaped molded product (see below) was molded by injection molding, and the molded product was immersed in 100% acetic acid for 5 minutes.
The presence or absence of cracks on the surface was visually determined.・ No cracks at all ◎ ◎ ・ Slight cracks only at the gate part ・ ・ ・ ○ ・ Some cracks at the gate part ・ ・ ・ △ ・ Cracks to the lower part of the molded product Generated or fractured ··· Evaluation of chemical resistance (dissolution) The same molded article as that in (1) was visually evaluated for the presence or absence of surface dissolution. · No dissolution ··· · Dissolved surface ··· × Appearance of molded article The appearance was judged visually.・ Welds are inconspicuous ○ ○ ・ Welds are noticeable × × <Shape and molding conditions of molded article used in-> 100 mm (side A) x 55 mm (side B) x side of roof A rectangular body having a thickness of 2 mm, an upper surface portion having a rectangular shape of 100 mm (side A ′) × 10 mm (side C) × thickness of 3 mm, and an upper surface portion and two side portions having sides A and A ′ of 120 mm Contact at an angle of degrees. There are three gate portions on the upper surface every 25 mm, and ribs (thicknesses 1, 2, and 3 respectively) are perpendicular to the upper surface from each gate to the lower portion of the side portion.
mm) is standing.・ Molding machine: AS-100B manufactured by FUNUC ・ Molding condition: Cylinder temperature: 240 ° C, Mold temperature:
60 ° C. Impact resistance 1/4 inc of 6 mm × 12.6 mm × 126 mm
h was molded by injection molding (molding machine; F
ANUC AS-100B, cylinder temperature 240
° C, mold temperature 45 ° C). The IZOD impact strength of the obtained test piece was measured based on ASTM-D256 and determined. (With notch) ・ IZOD impact strength is the same or higher than that of the standard product without adding PMMA resin or aliphatic polyester ・ ・ ・ ○ ・ Standard without adding PMMA resin or aliphatic polyester IZOD impact strength is lower than that of the product. × × ・ Standard ・ ・ ・-Peelability The fracture state of the sample after the IZOD impact test is visually observed to determine the peeling state. did. -No peeling is observed ...--Peeling is observed ... × <Synthesis Example 1 (A1) of graft copolymer (I)> Latex of polybutadiene rubber having an average particle diameter of 0.3 μm 40 parts by weight (in terms of solid content) and 100 parts by weight of deionized water were put into a polymerization tank equipped with a reflux condenser, and the temperature was raised to 70 ° C. while replacing the gas phase with nitrogen. Then, styrene 36
Parts by weight, 24 parts by weight of acrylonitrile, 0.7 parts by weight of t-dodecyl mercaptan, 0.12 parts by weight of cumene hydroperoxide, and 50 parts of deionized water.
Aqueous solution consisting of 0.2 parts by weight of sodium formaldehyde sulfoxylate, 0.012 parts by weight of ferrous sulfate, and 0.08 parts by weight of disodium ethylenediaminetetraacetate was continuously added for 5 hours. Reacted. During this time, the polymerization temperature was adjusted to 70 ° C., and after the completion of the additional addition, the state was maintained for another hour to complete the polymerization. The conversion was 95%. The obtained copolymer latex was subjected to coagulation and salting out, followed by washing and drying to obtain a white solid. <Synthesis Example 2 (A2) of Graft Copolymer (I)> 40 parts by weight (in terms of solid content) of a polybutadiene rubber latex having an average particle diameter of 0.3 μm and 100 parts by weight of deionized water are polymerized with a reflux condenser. The mixture was placed in a tank and heated to 70 ° C. while replacing the gas phase with nitrogen. Then, styrene 42
Parts by weight, 18 parts by weight of acrylonitrile, 0.5 part by weight of t-dodecyl mercaptan, 0.1 part by weight of cumene hydroperoxide, and 50 parts by weight of deionized water, 0.2 part by weight of sodium formaldehyde sulfoxylate , An aqueous solution consisting of 0.01 parts by weight of ferrous sulfate and 0.06 parts by weight of disodium ethylenediaminetetraacetate was added continuously for 5 hours to cause a reaction.
During this time, the polymerization temperature was adjusted to 70 ° C., and after the completion of the additional addition, the state was maintained for another hour to complete the polymerization. The conversion was 97%. The obtained copolymer latex was subjected to coagulation and salting out, followed by washing and drying to obtain a white solid. <Synthesis Example 3 (A3) of Graft Copolymer (I)> 40 parts by weight (in terms of solid content) of a polybutadiene rubber latex having an average particle diameter of 0.3 μm and 100 parts by weight of deionized water are polymerized with a reflux condenser. The mixture was placed in a tank and heated to 70 ° C. while replacing the gas phase with nitrogen. Then, styrene 48
Part by weight, 12 parts by weight of acrylonitrile, 0.4 part by weight of t-dodecyl mercaptan, 0.1 part by weight of cumene hydroperoxide, and 50 parts by weight of deionized water, 0.2 part by weight of sodium formaldehyde sulfoxylate , An aqueous solution consisting of 0.01 parts by weight of ferrous sulfate and 0.06 parts by weight of disodium ethylenediaminetetraacetate was added continuously for 5 hours to cause a reaction.
During this time, the polymerization temperature was adjusted to 70 ° C., and after the completion of the additional addition, the state was maintained for another hour to complete the polymerization. The conversion was 97%. The obtained copolymer latex was subjected to coagulation and salting out, followed by washing and drying to obtain a white solid. <Synthesis Example 1 of Copolymer (II) (B1)> Using a complete mixing type continuous reactor, while continuously adding a monomer solution composed of styrene, acrylonitrile and ethylbenzene at a constant rate, the reaction rate in the polymerization system The acrylonitrile content is 40% by weight, the styrene content is 60% by weight, and the number average molecular weight of acrylonitrile and styrene is 40,000 by adjusting the reaction temperature, the monomer composition and the amount of ethylbenzene used. A copolymer (B1) was obtained. <Synthesis Example 2 (B2) of Copolymer (II)> In the same manner as in the synthesis of (B1), acrylonitrile and styrene having an acrylonitrile content of 30% by weight, a styrene content of 70% by weight, and a number average molecular weight of 40,000 were used. A copolymer (B2) was obtained. <Synthesis Example 3 of Copolymer (II) (B3)> Acrylonitrile having a acrylonitrile content of 20% by weight, a styrene content of 80% by weight and a number average molecular weight of 50,000 was prepared in the same manner as in the synthesis of (B1). A copolymer (B3) was obtained. <Copolymer (III) (C1)> Commercially available polymethacrylic resin (PMMA) (560F, manufactured by Asahi Kasei Corporation)
It was used. The melt flow rate (JIS-K7112) at 220 ° C and 10 kg load is 40 g.
/ 10 minutes. <Copolymer (III) (C2)> A commercially available polymethacrylic resin (PMMA) (80N manufactured by Asahi Kasei Corporation) was used. Its melt flow rate (JIS-K7112) at 220 ° C and 10 kg load was 4 g / 1.
It was 0 minutes. <Aliphatic polyester (IV) (D1)> Commercially available polycaprolactone (molecular weight 70000) (PLACCEL H7 manufactured by Daicel Chemical Industries, Ltd.) was used.

[0027]

Example 1 40 parts by weight of (A1) obtained in Synthesis Example 1 of graft copolymer (I), 55 parts by weight of (B1) obtained in Synthesis Example 1 of copolymer (II), a homopolymer or 5 parts by weight of the copolymer (III) (C1) and 1 part by weight of the aliphatic polyester (IV) (D1) were melt-mixed using an extruder to obtain a resin composition. This was injection molded to obtain a roof-shaped molded product. When this molded article was immersed in 100% acetic acid for 5 minutes, the evaluation items were judged, and there was no problem. Table 1 shows the results.

[0028]

Examples 2 to 6 Resin compositions were obtained in the same manner as in Example 1, except that the proportions of the composition were changed to the amounts shown in Table 1. There was no problem as in Example 1. Table 1 shows the results.

[0029]

Comparative Example 1 Using an extruder, 40 parts by weight of (A1) obtained in Synthesis Example 1 of the graft copolymer (I) and 60 parts by weight of (B1) obtained in Synthesis Example 1 of the copolymer (II) were used. To obtain a resin composition. This was injection molded to obtain a molded product. When this molded product was immersed in 100% acetic acid for 5 minutes, a large crack was formed from the gate portion and the molded product was broken. Table 1 shows the results.

[0030]

Comparative Examples 2 to 5 Resin compositions were obtained in the same manner as in Example 1, except that the proportions of the composition were changed to the amounts shown in Table 1. As in Comparative Example 1, cracks are generated when immersed in acetic acid, the surface dissolves, welds are very conspicuous in appearance, impact resistance, peelability is problematic, or any other two or more performances It was inferior. Table 1 shows the results.

[0031]

[Table 1]

[0032]

The thermoplastic resin composition of the present invention is particularly excellent in acetic acid resistance and impact resistance. In particular, a molded article free from cracks can be obtained when a molded article is obtained by injection molding. It is very useful in industry.

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Claims (3)

[Claims] 1. A graft copolymer (I) obtained by copolymerizing a monomer component containing an aromatic vinyl monomer and a vinyl cyanide monomer as main components in the presence of a rubbery polymer; (II) obtained by copolymerizing a monomer component containing a group III vinyl monomer or a vinyl cyanide monomer as a main component and a monomer component containing methyl methacrylate as a main component Alternatively, a composition comprising a homopolymer or copolymer (III) obtained by copolymerization and an aliphatic polyester (IV), wherein the proportion of (III) in the composition is 1% by weight to 25% by weight. Hereinafter, when the ratio of (IV) is 0.
3% by weight or more and 10% by weight or less, and the ratio of vinyl cyanide in the components other than the rubbery polymer in (I) and (II) is 25% by weight or more and 50% by weight or less. Thermoplastic resin composition. 2. A melt flow rate (220 ° C., 10 kg load) of a homopolymer or a copolymer (III) obtained by homopolymerizing or copolymerizing a monomer component containing methyl methacrylate as a main component is 15 g. / 10 minutes or more 1
2. The thermoplastic resin composition according to claim 1, wherein the thermoplastic resin composition is not more than 00 g / 10 minutes. 3. A molded article obtained by injection molding the thermoplastic resin composition according to claim 1.