Thermoplastic resin composition and molding made of the same

Abstract

To provide a thermoplastic resin composition that is excellent in chemical resistance, is small in molding shrinkage rate, does not impair rigidity and has high impact resistance.SOLUTION: Using the total of (A) and (B) as 100 pts.wt, in the presence of a rubbery polymer, a graft copolymer (A) consisting of a mixture of vinyl monomers that includes at least cyanide vinyl monomer and aromatic vinyl monomer, should be 20 to 60 parts by weight, and a vinyl copolymer (B) consisting of a mixture of vinyl monomers that includes at least cyanide vinyl monomer and aromatic vinyl monomer should be 40 to 80 pts.wt., combined with 100 parts by weight of a styrene-based resin composition. Additionally, it should contain 1 to 4 pts.wt. of a polyolefin copolymer (C) obtained by copolymerizing ethylene, (meth)acrylic acid esters, and carbon monoxide and / or maleic anhydride, as well as 0.01 to 0.1 pts.wt. of a silicone compound (D), resulting in a thermoplastic resin composition.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a thermoplastic resin composition.

Background Art

[0002] An ABS resin obtained by graft copolymerizing a rubbery polymer such as a diene rubber with an aromatic vinyl compound such as styrene or α-methylstyrene and a vinyl cyanide compound such as acrylonitrile or methacrylonitrile is excellent in mechanical strength such as impact resistance and rigidity, moldability, appearance, and cost performance. Therefore, it is widely used in application fields such as home appliances, communication-related equipment, general goods, and medical-related equipment.

[0003] Furthermore, in applications such as cosmetic containers where the frequency of contact with chemicals that cause resin cracking is high, high chemical resistance is required. Generally, in an ABS resin, the higher the ratio of the vinyl cyanide compound to the aromatic vinyl compound, the more the chemical permeability can be suppressed by the intermolecular force caused by the cyano group, and the chemical resistance can be improved. However, in the method of increasing the ratio of the vinyl cyanide compound, as the ratio of the vinyl cyanide compound increases, the probability of generating a structure in which vinyl cyanide compounds are adjacent during copolymerization significantly increases, and adjacent vinyl cyanide compounds cause a cyclization reaction by heat, resulting in yellowing (heat coloring) during resin processing and impairing the color tone stability. Therefore, methods for improving chemical resistance by containing various additives have been studied.

[0004] Patent Document 1 reports that a chemical-resistant thermoplastic resin composition excellent in color tone stability during melting can be obtained by combining a rubber-containing graft copolymer having a rubber particle size and a graft ratio in a specific range, a vinyl cyanide-based copolymer having a specific structure, and a copolymer composed of ethylene / (meth)acrylate / carbon monoxide and / or an aromatic polyester-based polymer.

[0005] In Patent Document 2, it is reported that by containing a very small amount of silicone oil in a thermoplastic resin composition composed of a polyamide resin and a styrene resin containing a rubber-containing styrene resin, a thermoplastic resin composition having mechanical strength and good chemical resistance can be obtained.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0007] The resin composition described in Patent Document 1 improves chemical resistance by adding a polyolefin-based copolymer. However, when the addition amount increases, the molding shrinkage rate becomes high, and molding defects are likely to occur. On the other hand, if the addition amount is reduced, the desired chemical resistance cannot be maintained.

[0008] The resin composition described in Patent Document 2 improves impact resistance and chemical resistance by adding silicone oil. However, due to the addition of silicone, the resin composition may soften, and there is a risk of a decrease in rigidity, which is one of the characteristics of ABS.

Means for Solving the Problems

[0009] As a result of intensive studies on the combination of the resin composition and the additive and the balance of the formulation, in the present invention, as a means for solving the above problems, 20 to 60 parts by weight of a graft copolymer (A) obtained by graft copolymerizing a vinyl monomer mixture containing at least an aromatic vinyl monomer and a vinyl cyanide monomer in the presence of a rubbery polymer, and 40 to 80 parts by weight of a vinyl copolymer (B) obtained by copolymerizing a vinyl monomer mixture containing at least an aromatic vinyl monomer and a vinyl cyanide monomer. The thermoplastic resin contains 1 to 4 parts by weight of a polyolefin copolymer (C) obtained by copolymerizing ethylene and a (meth)acrylate ester with a compound selected from carbon monoxide or maleic anhydride, and 0.01 to 0.1 part by weight of a silicone compound (D) with respect to 100 parts by weight of the resin component. A thermoplastic resin composition is provided.

[0010] The present invention is as follows. (1) Based on 100 parts by weight of a styrene resin composition containing 20 to 60 parts by weight of a graft copolymer (A) obtained by graft copolymerizing a vinyl monomer mixture containing at least a vinyl cyanide monomer and an aromatic vinyl monomer in the presence of a rubbery polymer, and 40 to 80 parts by weight of a vinyl copolymer (B) obtained by copolymerizing a vinyl monomer mixture containing at least a vinyl cyanide monomer and an aromatic vinyl monomer, 1 to 4 parts by weight of a polyolefin copolymer (C) obtained by copolymerizing ethylene, a (meth)acrylate ester, and carbon monoxide and / or maleic anhydride, and 0.01 to 0.1 part by weight of a silicone compound (D). A thermoplastic resin composition. (2) The thermoplastic resin composition according to (1) or (2), wherein the vinyl copolymer (B) contains 39 to 70 parts by weight of the following vinyl copolymer (B-1) and 1 to 10 parts by weight of a vinyl copolymer (B-2) based on 100 parts by weight of the total of the graft copolymer (A) and the vinyl copolymer (B). Vinyl copolymer (B-1); It is obtained by copolymerizing 25 to 40% by weight of a vinyl cyanide monomer and 60 to 75% by weight of an aromatic vinyl monomer, and the copolymer having a composition in which the vinyl cyanide content is 2% by weight or more higher than the average vinyl cyanide content of the entire vinyl copolymer (B-1) is less than 40% by weight in the copolymer. Vinyl copolymer (B-2); It is obtained by copolymerizing 30 to 50% by weight of a vinyl cyanide monomer and 70 to 50% by weight of an aromatic vinyl monomer, and the copolymer having a composition in which the vinyl cyanide content is 2% by weight or more higher than the average vinyl cyanide content of the entire vinyl copolymer (B-2) is 40% by weight or more and 60% by weight or less in the copolymer. (3) The thermoplastic resin composition according to (3), wherein the weight average molecular weight of the vinyl copolymer (B-1) is 110,000 to 150,000. (4) The thermoplastic resin composition according to any one of (1) to (3), which contains 0.5 to 3.5 parts by weight of a polyhydric alcohol fatty acid ester (E) with respect to 100 parts by weight of the styrene resin composition. (5) A molded article made of the thermoplastic resin composition according to any one of (1) to (4). [[Effect of the Invention]]

[0011] The present invention can provide a thermoplastic resin composition that is excellent in chemical resistance, has a small molding shrinkage rate, and has high impact resistance without sacrificing rigidity. [[Brief Description of the Drawings]]

[0012]

Figure 1

[0013] In the thermoplastic resin composition of the present invention, the resin component, with the total of (A) and (B) being 100 parts by weight, is a graft copolymer (A) of 20 to 60 parts by weight obtained by graft copolymerizing a vinyl monomer mixture containing at least a vinyl cyanide monomer and an aromatic vinyl monomer in the presence of a rubbery polymer, and a vinyl copolymer (B) of 40 to 80 parts by weight obtained by copolymerizing a vinyl monomer mixture containing at least a vinyl cyanide monomer and an aromatic vinyl monomer, and includes a styrene resin composition. In the styrene resin composition of the present invention, in order to ensure impact resistance, the graft copolymer (A) (hereinafter, referred to as the rubber-containing graft and copolymer) needs to be 20 parts by weight or more, and preferably 30 parts by weight or more. Also, in order to maintain rigidity, the rubber-containing graft copolymer (A) needs to be 60 parts by weight or less, and preferably 50 parts by weight or less.

[0014] In the styrene resin composition of the present invention, in order to ensure good moldability, the vinyl copolymer (B) needs to be 40 parts by weight or more, and preferably 50 parts by weight or more. Also, in order to maintain impact resistance, the rubber-containing graft copolymer (A) needs to be 80 parts by weight or less, and preferably 70 parts by weight or less.

[0015] Examples of the rubbery polymer used for the rubber-containing graft copolymer (A) in the present invention include diene rubbers, acrylic rubbers, and ethylene rubbers. Specific examples include polybutadiene, poly(butadiene-styrene), poly(butadiene-acrylonitrile), polyisoprene, poly(butadiene-butyl acrylate), poly(butadiene-methyl acrylate), poly(butadiene-methyl methacrylate), poly(butyl acrylate-methyl methacrylate), poly(butadiene-ethyl acrylate), ethylene-propylene rubber, ethylene-propylene-diene rubber, poly(ethylene-isobutylene), poly(ethylene-methyl acrylate), and the like. These rubbery polymers are used as a single species or a mixture of two or more species. Among these rubbery polymers, polybutadiene, poly(butadiene-styrene), poly(butadiene-acrylonitrile), and ethylene-propylene rubber are particularly preferred in terms of impact resistance.

[0016] Specific examples of the vinyl cyanide monomer (a) used for the rubber-containing graft copolymer (A), vinyl copolymer (B-1), and vinyl copolymer (B-2) that constitute the styrene resin composition in the present invention include acrylonitrile and methacrylonitrile, and one or more of them can be used. Among them, acrylonitrile is particularly preferred in terms of chemical resistance.

[0017] Specific examples of the aromatic vinyl monomer (b) used for the rubber-containing graft copolymer (A), vinyl copolymer (B-1), and vinyl copolymer (B-2) that constitute the styrene resin composition in the present invention include styrene, α-methylstyrene, orthomethylstyrene, paramethylstyrene, para-t-butylstyrene, and halogenated styrene, and one or more of them can be used. Among them, styrene and α-methylstyrene are preferred in terms of moldability, and styrene is particularly preferred.

[0018] Specific examples of the other copolymerizable vinyl monomer (c) used in the rubber-containing graft copolymer (A) constituting the styrene resin composition of the present invention include unsaturated carboxylic acids such as acrylic acid and methacrylic acid; (meth)acrylic esters such as methyl acrylate, methyl methacrylate, and butyl acrylate; (meth)acrylamides such as acrylamide, methacrylamide, and N-methylacrylamide, and maleimides such as maleimide, N-methylmaleimide, and N-phenylmaleimide, and unsaturated carboxylic acid anhydrides such as maleic anhydride, citraconic anhydride, and aconitic anhydride. Among them, methyl methacrylate and N-phenylmaleimide are preferable in terms of moldability.

[0019] The content of the rubber polymer used in the rubber-containing graft copolymer (A) in the present invention is not particularly limited, but it is preferably 10% by weight or more from the viewpoint of impact resistance, and more preferably 40% by weight or more. Also, it is preferably 80% by weight or less from the viewpoint of moldability, and more preferably 70% by weight or less.

[0020] The content of the vinyl cyanide monomer (a) in the rubber-containing graft copolymer (A) is not particularly limited, but it is preferably 5% by weight or more from the viewpoint of chemical resistance, and more preferably 10% by weight or more. Also, it is preferably 50% by weight or less from the viewpoint of moldability, and more preferably 40% by weight or less.

[0021] The content of the aromatic vinyl monomer (b) in the rubber-containing graft copolymer (A) is not particularly limited, but it is preferably 10% by weight or more from the viewpoint of moldability, and more preferably 20% by weight or more. Also, it is preferably 80% by weight or less from the viewpoint of impact resistance, and more preferably 70% by weight.

[0022] The content of the other copolymerizable vinyl monomer (c) in the rubber-containing graft copolymer (A) is not particularly limited, but it is preferably 50% by weight or less from the viewpoint of moldability.

[0023] As a method for producing the rubber-containing graft copolymer (A), it can be produced by any polymerization method such as emulsion polymerization, suspension polymerization, bulk polymerization, and solution polymerization. Further, there are no particular restrictions on the charging method of each monomer, and it may be charged all at once initially, or in order to suppress the composition distribution of the copolymer, a part or all of the charged monomers may be charged and polymerized continuously or dividedly.

[0024] The average vinyl cyanide content of the vinyl copolymer (B) in the present invention is not particularly limited, but is preferably 25% by weight or more from the viewpoint of chemical resistance, and more preferably 30% by weight or more. Further, it is preferably 50% by weight or less from the viewpoint of color tone stability during melting, and more preferably 38% by weight or less.

[0025] The average vinyl cyanide content of the vinyl copolymer (B) in the present invention is calculated using an infrared spectrophotometer. Specifically, the content of the vinyl cyanide monomer unit was quantified from the intensity ratio of the following peaks. Aromatic vinyl monomer: 1605 cm attributed to the vibration of the benzene nucleus -1 peak Vinyl cyanide monomer: 2240 cm attributed to -C≡N stretching -1 peak

[0026] The vinyl copolymer (B) in the present invention preferably contains 39 parts by weight or more, more preferably 50 parts by weight or more, and preferably 70 parts by weight or less of the following vinyl copolymer (B-1) with respect to 100 parts by weight of the styrene resin component from the viewpoint of color tone stability during melting. Further, from the viewpoint of chemical resistance, it preferably contains 1 part by weight or more of the vinyl copolymer (B-2), and is preferably 10 parts by weight or less in order to avoid deterioration of the color tone during melting.

[0027] In the composition distribution of vinyl cyanide in the vinyl copolymer (B-1) in the present invention, it is preferable that the copolymer having a vinyl cyanide content 2% by weight or more higher than the average vinyl cyanide content of the entire vinyl copolymer (B-1) is less than 40% by weight in the copolymer (B-1), and more preferably 20% or less. The more single and sharp the peak of the chart of the composition distribution of the obtained vinyl cyanide is, the more improved the color tone stability during melting is.

[0028] The composition distribution of vinyl cyanide in the vinyl copolymer (B-1) in the present invention is obtained by adding cyclohexane to a methyl ethyl ketone solution of the vinyl copolymer, drying the fractionally precipitated vinyl copolymer, measuring its weight, and then determining the vinyl cyanide content with an infrared spectrophotometer. The obtained weight is converted into 100 fractions, the frequency is plotted on the vertical axis, and the vinyl cyanide content is plotted on the horizontal axis to obtain the composition distribution of vinyl cyanide.

[0029] The weight average molecular weight of the vinyl copolymer (B-1) in the present invention is preferably 110,000 or more from the viewpoint of chemical resistance, and more preferably 120,000 or more. Further, if it exceeds 150,000, the fluidity deteriorates and the molding processability is poor, so it is preferably 150,000 or less, and more preferably 140,000 or less.

[0030] The weight average molecular weight of the vinyl copolymer (B-1) in the present invention is determined by converting from a GPC chromatogram measured using tetrahydrofuran as a solvent and polystyrene as a standard substance.

[0031] In the composition distribution of vinyl cyanide in the vinyl copolymer (B-2) in the present invention, it is preferable that the copolymer having a vinyl cyanide content 2% by weight or more higher than the average vinyl cyanide content of the entire vinyl copolymer (B-2) is 40% by weight or more in the copolymer (B-2), and more preferably 45% by weight or more. If it is less than 40% by weight, the chemical resistance of the obtained thermoplastic resin composition is not sufficient. Also, in order to stabilize the color tone during melting, it is preferably 60% by weight or less, and more preferably 55% by weight or less.

[0032] The compositional distribution of vinyl cyanide in the vinyl copolymer (B-2) in the present invention is determined by the same method as that of the vinyl copolymer (B-1).

[0033] As a method for producing the vinyl copolymer (B), it can be produced by any polymerization method such as emulsion polymerization, suspension polymerization, bulk polymerization, and solution polymerization. However, for the vinyl copolymer (B-1), suspension polymerization is preferred because the copolymer having a composition in which the vinyl cyanide content is 2% by weight or more higher than the average vinyl content is less than 40% by weight in the copolymer. Further, for the vinyl copolymer (B-2), bulk polymerization is preferred because the copolymer having a composition in which the vinyl cyanide content is 2% by weight or more higher than the average vinyl content is 40% by weight or more and 60% by weight or less in the copolymer. Further, there are no particular restrictions on the charging method of each monomer, and it may be charged all at once initially, or a part or all of the charged monomers may be polymerized while being continuously or dividedly charged in order to suppress the compositional distribution of the copolymer.

[0034] In the present invention, by blending the above styrenic resin composition with a polyolefin copolymer (C) obtained by copolymerizing ethylene, (meth)acrylate, and carbon monoxide and / or maleic anhydride, the thermoplastic resin composition containing the rubber-containing graft copolymer (A) and the vinyl copolymer (B) has the effect of imparting excellent chemical resistance and impact resistance.

[0035] The (meth)acrylate in the polyolefin copolymer (C) may be linear or branched, and the number of carbon atoms in the side chain is preferably 1 to 18, and examples include methyl group, ethyl group, n-propyl group, n-butyl group, sec-butyl group, t-butyl group, isobutyl group, hexyl group, 2-ethylhexyl group, octyl group, dodecyl group, undecyl group, stearyl group, etc. Particularly from the viewpoint of chemical resistance, the number of carbon atoms in the side chain is more preferably 1 to 4.

[0036] As the polyolefin copolymer (C), an ethylene / methyl acrylate / maleic anhydride copolymer or an ethylene / carbon monoxide / (meth)acrylate copolymer can be preferably used.

[0037] In the present invention, the blending amount of the polyolefin copolymer (C) is required to be 1 part by weight or more, preferably 2 parts by weight or more, based on 100 parts by weight of the styrenic resin composition containing the rubber-containing graft copolymer (A) and the vinyl copolymer (B) from the viewpoint of chemical resistance. If it is less than 1 part by weight, sufficient chemical resistance cannot be obtained. On the other hand, if it exceeds 4 parts by weight, the molding shrinkage rate increases, the molding processability deteriorates, and delamination occurs on the surface of the molded article, resulting in a decrease in the appearance of the molded article surface. Therefore, the content needs to be 4 parts by weight or less, preferably 3 parts by weight or less.

[0038] The silicone compound (D) in the present invention has the effect of imparting excellent impact resistance and chemical resistance to the thermoplastic resin composition containing the rubber-containing graft copolymer (A) and the vinyl copolymer (B).

[0039] The silicone compound (D) preferably has a kinematic viscosity at 25°C of 10000 mm 2 / s or more, more preferably 20000 mm 2 / s or more, from the viewpoints of impact resistance and chemical resistance. Also, from the viewpoint of molding processability, it is preferably 90000 mm 2 / s or less, more preferably 50000 mm 2 / s or less.

[0040] Examples of the silicone compound (D) used in the present invention include polydimethylsiloxane, polyphenylmethylsiloxane, or a copolymer of dimethylsiloxane and diphenylsiloxane, and mixtures thereof. Polydimethylsiloxane is preferred. The silicone compound may be used alone or in combination of two or more.

[0041] In the present invention, the compounding amount of the silicone compound (D) is required to be 0.01 part by weight or more, more preferably 0.03 or more, from the viewpoints of impact resistance and chemical resistance, based on 100 parts by weight of the thermoplastic styrene resin composition containing the rubber-containing graft copolymer (A) and the vinyl copolymer (B). Further, it is necessary to be 0.1 part by weight or less, more preferably 0.07 or less, in order to maintain rigidity.

[0042] By including the polyhydric alcohol fatty acid ester (E) in the thermoplastic resin composition containing the rubber-containing graft copolymer (A) and the vinyl copolymer (B) of the present invention, the extrusion processability and the mold release property during molding are improved, and furthermore, the chemical resistance can be improved.

[0043] Examples of the polyhydric alcohol fatty acid ester (E) include esters of higher fatty acids having 10 to 24 carbon atoms and polyhydric alcohols such as ethylene glycol, glycerin, 1,2,4-butanetriol, diglycerin, pentaerythritol, sorbitol, erythritol, and hexanetriol. Esters of higher fatty acids having 10 to 24 carbon atoms and pentaerythritol are preferable from the viewpoint of improving chemical resistance, and esters of stearic acid and pentaerythritol are more preferable. The ester may be any of monoester, diester, triester, and tetraester, or a mixture thereof.

[0044] In the present invention, the compounding amount of the polyhydric alcohol fatty acid ester (E) is preferably 0.5 part by weight or more, more preferably 0.7 part by weight or more, from the viewpoint of chemical resistance, based on 100 parts by weight of the styrene resin composition containing the graft copolymer (A) and the vinyl copolymer (B). Further, it is preferably 3.5 parts by weight or less, more preferably 2.0 parts by weight or less, in order to improve the extrusion processability during melt kneading.

[0045] In the thermoplastic resin composition of the present invention, within a range not impairing the effects of the present invention and, if necessary, inorganic fillers such as glass fiber, glass powder, glass beads, glass flakes, alumina, alumina fiber, carbon fiber, graphite fiber, stainless steel fiber, whisker, potassium titanate fiber, wollastonite, asbestos, hard clay, fired clay, talc, kaolin, mica, calcium carbonate, magnesium carbonate, aluminum oxide and minerals; antioxidants such as hindered phenol-based, sulfur-containing compound-based or phosphorus-containing organic compound-based; heat stabilizers such as phenol-based and acrylate-based; ultraviolet absorbers such as benzotriazole-based, benzophenone-based or salicylate-based; hindered amine-based light stabilizers; lubricants and plasticizers such as higher fatty acids, acid esters, acid amides or higher alcohols; mold release agents such as montanic acid and its salts, its esters, its half esters, stearyl alcohol, stearamide and ethylene wax; various flame retardants; flame retardant aids; coloring inhibitors such as phosphites and hypophosphites; neutralizing agents such as phosphoric acid, sodium phosphate monobasic, maleic anhydride, succinic anhydride; nucleating agents; antistatic agents such as amine-based, sulfonic acid-based, polyether-based; colorants such as carbon black, pigments, dyes, etc. can be blended.

[0046] The thermoplastic resin composition of the present invention can be obtained by melt-kneading a rubber-containing graft copolymer (A), a vinyl copolymer (B), a polyolefin copolymer (C), a silicone compound (D) and, if necessary, other components. Examples of the melt-kneading machine include a kneader, a Banbury mixer, a single-screw or twin-screw extruder, etc. The melt-kneading temperature is preferably 200 to 300 °C, and more preferably 220 to 270 °C from the viewpoint of suppressing yellowing during resin processing. The obtained thermoplastic resin composition is generally pelletized by a pelletizer and used.

Examples

[0047] Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. First, the evaluation methods in the examples will be described.

[0048] (1) Weight-average molecular weight of the vinyl copolymer (B) Using a gel permeation chromatography (GPC) apparatus manufactured by Waters, with a differential refractometer (Waters 2414) as the detector, two MIXED-B columns manufactured by Polymer Laboratories as the columns, and acetone as the eluent, the weight-average molecular weight in terms of polystyrene (PS) was measured under the conditions of a flow rate of 1 ml / min and a column temperature of 40°C.

[0049] (2) Average vinyl cyanide content in the vinyl copolymer (B) 1 g of the sample was formed into a film of about 40 μm by hot pressing, and the average vinyl cyanide content was determined from the ratio of the heights of the respective peaks that appeared in the chart obtained by analyzing with a Fourier transform infrared spectrophotometer (FT / IR4100 manufactured by Nippon Bunko Kabushiki Kaisha). The correspondence between each structural unit and the peak is as follows. Structural unit derived from styrene: Peak at 1605 cm attributed to the vibration of the benzene nucleus -1 of the peak. Structural unit derived from acrylonitrile: Peak at 2240 cm attributed to the stretching of -C≡N -1 of the peak.

[0050] (3) Vinyl cyanide composition distribution in the vinyl copolymer (B) 2 g of the sample was dissolved in 80 ml of methyl ethyl ketone, cyclohexane was added thereto, the precipitated vinyl cyanide copolymer was dried in vacuo and weighed, and the vinyl cyanide content of the vinyl cyanide copolymer was determined from the ratio of the peak heights obtained by analyzing with the above Fourier transform infrared altimeter. The cumulative weight % and the vinyl cyanide content were plotted, and the ratio (%) of 2% by weight or more was determined from the average vinyl cyanide content determined in (2).

[0051] (4) Critical strain value ε (chemical resistance) Pellets of the thermoplastic resin composition dried in a hot air dryer at a temperature of 80°C for 3 hours were molded using an injection molding machine PS60E-12A manufactured by Nissei Plastic Industrial Co., Ltd. with the cylinder temperature set at 230°C and the mold temperature set at 60°C to obtain strip-shaped test pieces (length 127 mm, width 12.7 mm, thickness 1.5 mm). The test pieces were annealed in a hot air dryer at a temperature of 80°C for 24 hours, left standing at room temperature of 23°C and humidity of 50% for 24 hours, then fixed along the 1 / 4 elliptical jig shown in Figure 1. After that, bis(2-ethylhexyl) phthalate diluted with hexane was applied to the entire surface of the test pieces. After the hexane, which is the diluent, had evaporated, the test pieces were left standing at room temperature of 23°C and humidity of 50% for 72 hours. Then, based on Formula 1, the critical strain value ε (%) was calculated from the position of the cracks generated on the test pieces.

[0052]

Number

[0053] ε: Critical strain (%), a: Major axis of the jig (mm), b: Minor axis of the jig (mm), t: Thickness of the test piece (mm), X: Length in the major axis direction of the crack generation point (mm) (a, b, and t are constants, where a = 127, b = 49, and t = 1.5).

[0054] (5) Molding shrinkage rate (molding shrinkability) Pellets of the thermoplastic resin composition dried in a hot air dryer at a temperature of 80°C for 3 hours were molded using an injection molding machine PS60E-12A manufactured by Nissei Plastic Industrial Co., Ltd. with the cylinder temperature set at 230°C and the mold temperature set at 60°C to obtain test pieces of 150 mm (W) × 150 mm (L) × 3 mm (t). After leaving them standing at room temperature of 23°C and humidity of 50% for 24 hours, the shrinkage rates in the flow direction (longitudinal direction, MD) and the direction perpendicular to the flow (transverse direction, TD) of the molded products were measured with a caliper.

[0055] (6) Flexural modulus (rigidity) Pellets of the thermoplastic resin composition dried in a hot air dryer at a temperature of 80°C for 3 hours were molded into multi-purpose test piece type A1 specified in JIS K 7139 using an injection molding machine SE-50EV manufactured by Sumitomo Heavy Industries, Ltd. with a cylinder temperature of 230°C and a mold temperature set at 60°C. Using the cut-out type B2 test pieces, the flexural modulus was measured in accordance with ISO178.

[0056] (7) Charpy impact value (impact resistance) Pellets of the thermoplastic resin composition dried in a hot air dryer at a temperature of 80°C for 3 hours were molded into multi-purpose test piece type A1 specified in JIS K 7139 using an injection molding machine SE-50EV manufactured by Sumitomo Heavy Industries, Ltd. with a cylinder temperature of 230°C and a mold temperature set at 60°C. Using the cut-out type B2 test pieces, the Charpy impact strength was measured in accordance with ISO179 / 1eA.

[0057] (Reference Example 1) Production of rubber-containing graft copolymer (A) Using a nitrogen-substituted reactor, in the presence of 45 parts by weight (in terms of solid content) of polybutadiene latex (a combination of two types with a weight average particle diameter of 350 nm and 800 nm, ratio 7:3), a monomer mixture consisting of 15 parts by weight of acrylonitrile and 40 parts by weight of styrene was subjected to emulsion polymerization using potassium stearate to obtain a rubber-reinforced styrene resin latex. This was added to a 0.3% dilute sulfuric acid aqueous solution at a temperature of 90°C, coagulated, neutralized with an aqueous sodium hydroxide solution, and then subjected to a washing, dehydration, and drying process to obtain a rubber-containing graft copolymer (A).

[0058] (Reference Example 2) Production of vinyl copolymer (B-1) (B-1-1) A continuous bulk polymerization apparatus consisting of an evaporative dry distillation condenser for monomer vapor and a completely mixed polymerization tank with a helical ribbon blade, a single-screw extruder type preheater, and a twin-screw extruder type de-monomerizer was used. A monomer mixture consisting of 34 parts by weight of acrylonitrile, 66 parts by weight of styrene, 0.185 parts by weight of n-octyl mercaptan, and 0.0184 parts by weight of 1,1-bis(t-butylperoxy)cyclohexane was continuously supplied to the completely mixed polymerization tank and continuously bulk polymerized. Next, the polymerization reaction mixture was preheated by a single-screw extruder type preheater and then supplied to a twin-screw extruder type de-monomerizer. The unreacted monomer was recovered by vacuum evaporation from the vent port of the twin-screw extruder type de-monomerizer. The recovered unreacted monomer was continuously refluxed to the completely mixed polymerization tank. Thereafter, the melt-kneaded product was discharged in a strand form and cut by a cutter to obtain a pelletized vinyl copolymer (B-1-1). The weight average molecular weight of the obtained vinyl copolymer was 132,000, the average vinyl cyanide content was 34%, and the ratio of 2% by weight or more higher than the average vinyl cyanide content was 10%.

[0059] (B-1-2) A vinyl copolymer (B-1-2) was obtained in the same manner as (B-1-1) except that the composition was changed to 28 parts by weight of acrylonitrile, 72 parts by weight of styrene, 0.3 parts by weight of n-octyl mercaptan, and 0.008 parts by weight of 1,1-bis(t-butylperoxy)cyclohexane. The weight average molecular weight of the obtained vinyl copolymer was 95,000. The average vinyl cyanide content was 28%, and the ratio of 2% by weight or more higher than the average vinyl cyanide content was 10%.

[0060] (Reference Example 3) Production of Vinyl Copolymer (B-2) Using a stainless steel autoclave equipped with a baffle and a paddle-type stirring blade, a solution prepared by dissolving 0.05 part of a methyl methacrylate / acrylamide copolymer (described in Japanese Patent Publication No. 45-24151) in 165 parts of ion-exchanged water was stirred at 400 rpm, and the inside of the system was replaced with nitrogen gas. Next, a mixed solution of 37 parts by weight of acrylonitrile, 63 parts by weight of styrene, 0.3 part by weight of t-dodecyl mercaptan, and 0.52 part of 2,2'-azobisisobutyronitrile was added while stirring the reaction system, and polymerization was carried out. Thereafter, according to a usual method, the reaction system was cooled, the polymer was separated, washed, and dried to obtain a vinyl copolymer (B-2). The average vinyl cyanide content of the obtained vinyl copolymer (B-2) was 37%, and the proportion of 2% by weight or more based on the average vinyl cyanide content was 52%.

[0061] (Reference Example 4) Polyolefin copolymer (C) (C-1) "Lotader (registered trademark)" 4613 (ethylene / methyl acrylate / maleic anhydride copolymer) manufactured by Arkema Co., Ltd. was used.

[0062] (C-2) "Elvaloy (registered trademark)" HP-4051 (ethylene / carbon monoxide / (meth)acrylate copolymer) manufactured by Mitsui Dow Polychemical Co., Ltd. was used.

[0063] (Reference Example 5) Silicone compound (D) "DOWSIL (registered trademark)" SH 200 Fluid 30,000 cSt manufactured by DuPont-Toray Specialty Materials Co., Ltd. was used. The kinematic viscosity at 25°C was 30,000 mm 2 / s.

[0064] (Reference Example 6) Polyhydric alcohol fatty acid ester (E) "Kemal (registered trademark)" HT-10 (pentaerythritol tetrastearate) manufactured by Riken Vitamin Co., Ltd. was used.

[0065] Hereinafter, examples and comparative examples will be described.

[0066] The rubber-containing graft copolymer (A), vinyl copolymer (B), polyolefin copolymer (C), silicone compound (D), and polyhydric alcohol fatty acid ester (E) described in the reference example were blended in the parts by weight shown in Tables 1 to 2, and using a single-screw extruder with a vent (FS40 manufactured by Ikegai Corporation) having a screw diameter of 40 mm, melt kneading was carried out under the conditions of a cylinder set temperature of 230°C and a screw rotation speed of 80 rpm to obtain pellets of the resin composition.

[0067] After drying the obtained pellets of the thermoplastic resin composition in a box-type hot air dryer set at 100°C for 3 hours or more, various test pieces were produced using an injection molding machine as described in the reference example, and various evaluations were carried out. The results of the examples and reference examples are shown in Table 1, and the results of the comparative examples are shown in Table 2.

[0068]

Table 1

[0069]

Table 2

[0070] From the evaluation results in Table 1, it can be seen that the thermoplastic resin compositions of the present invention (Examples 1 to 13) are all excellent in chemical resistance, molding shrinkage, rigidity, and impact resistance.

[0071] On the other hand, in Comparative Example 1 of Table 2, since the blending amount of the rubber-containing graft copolymer (A) is small, the chemical resistance and impact resistance are low. In Comparative Example 2, since the blending amount of the vinyl copolymer (B) is small, the rigidity is greatly inferior. In Comparative Example 3, since there is no polyolefin copolymer (C), the chemical resistance is low. In Comparative Examples 4 and 5, since the blending amount of the polyolefin copolymer (C) is large, the molding shrinkage rate is large and the molding shrinkage property is inferior. In Comparative Example 6, since there is no silicone compound (D), the chemical resistance is low, and in Comparative Example 7, since the blending amount of the silicone compound (D) is large, the rigidity is inferior.

Explanation of symbols

[0072] a: Long axis of the jig (mm) b: Short axis of the jig (mm) X: Length in the long axis direction of the crack generation point (mm)

Claims

1. Based on 100 parts by weight of the total of (A) and (B), in the presence of a rubbery polymer, a vinyl monomer mixture containing at least a vinyl cyanide monomer and an aromatic vinyl monomer is graft copolymerized to obtain 20 to 60 parts by weight of a graft copolymer (A), and a vinyl copolymer (B) obtained by copolymerizing a vinyl monomer mixture containing at least a vinyl cyanide monomer and an aromatic vinyl monomer is 40 to 80 parts by weight. For 100 parts by weight of the styrene resin composition, 1 to 4 parts by weight of a polyolefin copolymer (C) obtained by copolymerizing ethylene, (meth)acrylate, and carbon monoxide and / or maleic anhydride, and 0.01 to 0.1 parts by weight of a silicone compound (D). A thermoplastic resin composition.

2. The vinyl copolymer (B) contains 39 to 70 parts by weight of the following vinyl copolymer (B-1) and 1 to 10 parts by weight of a vinyl copolymer (B-2) based on 100 parts by weight of the total of the graft copolymer (A) and the vinyl copolymer (B). The thermoplastic resin composition according to Claim 1. Vinyl copolymer (B-1); A copolymer obtained by copolymerizing 25 to 40% by weight of a vinyl cyanide monomer and 60 to 75% by weight of an aromatic vinyl monomer, and having a composition in which the vinyl cyanide content is 2% by weight or more higher than the average vinyl cyanide content of the entire vinyl copolymer (B-1), and the copolymer having such a composition is less than 40% by weight in the copolymer. A vinyl copolymer. Vinyl copolymer (B-2); A copolymer obtained by copolymerizing 30 to 50% by weight of a vinyl cyanide monomer and 70 to 50% by weight of an aromatic vinyl monomer, and having a composition in which the vinyl cyanide content is 2% by weight or more higher than the average vinyl cyanide content of the entire vinyl copolymer (B-2), and the copolymer having such a composition is 40% by weight or more and 60% by weight or less in the copolymer. A vinyl copolymer.

3. The thermoplastic resin composition according to Claim 3, wherein the weight average molecular weight of the vinyl copolymer (B-1) is 110,000 to 150,000.

4. The thermoplastic resin composition according to Claim 1, which contains 0.5 to 3.5 parts by weight of a polyhydric alcohol fatty acid ester (E) based on 100 parts by weight of the styrene resin composition.

5. A molded article made of the thermoplastic resin composition according to any one of Claims 1 to 4.

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