Maleimide-based copolymer, maleimide-based copolymer composition, resin composition, and injection-molded body

Abstract

To provide a maleimide-based copolymer which can obtain a resin composition having excellent fluidity and a low yellow index (YI) while maintaining a balance of heat resistance and impact resistance, and a maleimide-based copolymer composition, a resin composition, and an injection-molded body using the same. According to the present invention, a maleimide-based copolymer containing an aromatic vinyl monomer unit, a cyano-containing vinyl monomer unit, and a maleimide monomer unit, having a weight average molecular weight of 50,000 to 110,000, and a midpoint glass transition temperature of 165°C to 200°C measured according to JIS K-7121 can be provided.

Description

TECHNICAL FIELD

[0001] The present application relates to a maleimide-based copolymer, a maleimide-based copolymer composition, a resin composition, and an injection-molded body. BACKGROUND

[0002] Acrylonitrile-butadiene-styrene copolymer resins (ABS resins) are widely used in the fields of automobiles, home appliances, OA equipment, housing materials, and daily necessities, etc. due to their excellent mechanical strength, appearance, chemical resistance, moldability, etc. In applications to interior materials for automobiles, which require heat resistance, ABS resins containing a maleimide-based copolymer are used as a heat resistance-imparting material (for example, Patent Literature 1, Patent Literature 2).

[0003] ABS resins containing a maleimide-based copolymer have a drawback of low chemical resistance, and in order to overcome this drawback, a maleimide-based copolymer copolymerized with a cyano-containing vinyl monomer has been proposed (for example, Patent Literature 3, Patent Literature 4).

[0004] PRIOR ART DOCUMENTS

[0005] PATENT LITERATURE

[0006] Patent Literature 1: Japanese Patent Application Laid-Open No. 57-98536

[0007] Patent Literature 2: Japanese Patent Application Laid-Open No. 57-125242

[0008] Patent Literature 3: Japanese Patent Application Laid-Open No. 2004-339280

[0009] Patent Literature 4: Japanese Patent Application Laid-Open No. 2007-9228 SUMMARY

[0010] PROBLEMS TO BE SOLVED BY THE INVENTION

[0011] The maleimide-based copolymer copolymerized with a cyano-containing vinyl monomer proposed at present has high heat resistance, but on the other hand, there is a demand for improvement in flowability during molding. In addition, the maleimide-based copolymer containing a cyano-containing vinyl monomer has a tendency to be colored yellow, and this is a problem particularly when the molded product is used for a white application.

[0012] Therefore, an object of the present application is to provide a maleimide-based copolymer which can obtain a resin composition having excellent flowability and a low yellow index (YI) while maintaining a balance of heat resistance-imparting property and impact resistance; a maleimide-based copolymer composition using the maleimide-based copolymer; a resin composition; and an injection-molded body.

[0013] MEANS FOR SOLVING THE PROBLEMS

[0014] That is, the gist of the present application is as follows.

[0015] (1) A maleimide-based copolymer containing an aromatic vinyl monomer unit, a cyano-containing vinyl monomer unit, and a maleimide monomer unit, having a weight average molecular weight of 500,000 to 1,100,000, and a midpoint glass transition temperature of 165°C to 200°C as measured according to JIS K-7121.

[0016] (2) The maleimide-based copolymer according to (1), wherein a yellow index as measured according to JIS K-7373 is 0.5 to 3.5.

[0017] (3) The maleimide-based copolymer according to (1) or (2), containing 40 to 60 mass% of the aromatic vinyl monomer unit, 5 to 20 mass% of the cyano-containing vinyl monomer unit, and 30 to 50 mass% of the maleimide monomer unit as monomer units constituting the maleimide-based copolymer.

[0018] (4) A maleimide-based copolymer composition containing 100 parts by mass of the maleimide-based copolymer according to any one of (1) to (3), and 0 to 20 parts by mass of a copolymer other than the maleimide-based copolymer, the copolymer other than the maleimide-based copolymer being a copolymer containing a cyano-containing vinyl monomer unit and an aromatic vinyl monomer unit.

[0019] (5) A resin composition containing 5 to 40 mass% of the maleimide-based copolymer according to any one of (1) to (3); and 60 to 95 mass% of one or two or more kinds of resin selected from the group consisting of an acrylonitrile-butadiene-styrene copolymer resin, an acrylonitrile-styrene-acrylic rubber copolymer resin, an acrylonitrile-ethylene-propylene rubber-styrene copolymer resin, and a styrene-acrylonitrile copolymer resin.

[0020] (6) A resin composition containing 5 to 40 mass% of the maleimide-based copolymer composition according to (4); and 60 to 95 mass% of one or two or more kinds of resin selected from the group consisting of an acrylonitrile-butadiene-styrene copolymer resin, an acrylonitrile-styrene-acrylic rubber copolymer resin, an acrylonitrile-ethylene-propylene rubber-styrene copolymer resin, and a styrene-acrylonitrile copolymer resin.

[0021] (7) An injection-molded body using the resin composition according to (5) or (6).

[0022] (8) The injection-molded body according to (7) for use as an interior or exterior member of an automobile.

[0023] Effects of the Invention

[0024] According to the present application, there are provided a maleimide-based copolymer which can obtain a resin composition having excellent flowability and a low yellow index (YI) while maintaining a balance of heat resistance-imparting properties and impact resistance; a maleimide-based copolymer composition using the maleimide-based copolymer; a resin composition; and an injection-molded body. DETAILED DESCRIPTION

[0025] <Explanation of Terms>

[0026] In the present specification, for example, a description such as "A to B" means A or more and B or less.

[0027] The present application will be described in detail below. The maleimide-based copolymer of the present application is obtained by copolymerizing an aromatic vinyl monomer, a cyano-containing vinyl monomer, and a maleimide monomer.

[0028] The aromatic vinyl monomer that can be used in the maleimide-based copolymer is a monomer for improving the hue of the maleimide-based copolymer, and examples include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, 2,4-dimethylstyrene, ethylstyrene, p-t-butylstyrene, α-methylstyrene, and α-methyl-p-methylstyrene. Among these, styrene is preferred because of its good hue-improving effect. The aromatic vinyl monomer can be used alone or in combination of two or more.

[0029] The amount of the aromatic vinyl monomer unit contained in 100 mass% of the maleimide-based copolymer is preferably 40 to 60 mass%, and more preferably 45 to 55 mass%. Specifically, it is, for example, 40, 45, 46, 47, 48, 49, 50, 55, or 60 mass%, and can also be within a range between any two of the values exemplified herein. If the amount of the aromatic vinyl monomer unit is less than 40 mass%, the yellow index (YI) of the maleimide-based copolymer sometimes becomes high, and if it is more than 60 mass%, the heat resistance of the maleimide-based copolymer sometimes decreases.

[0030] The cyano-containing vinyl monomer that can be used in the maleimide-based copolymer is a monomer for improving the flowability and chemical resistance of the maleimide-based copolymer, and examples include acrylonitrile, methacrylonitrile, ethacrylonitrile, and fumaronitrile. Among these, acrylonitrile is preferred because of its good chemical resistance-improving effect. The cyano-containing vinyl monomer can be used alone or in combination of two or more.

[0031] The amount of the cyan-containing vinyl monomer unit contained in 100 mass% of the maleimide-based copolymer is preferably 5 to 20 mass%, more preferably 7 to 15 mass%. Specifically, for example, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 20 mass%, or a range between any two of the values exemplified herein can be used. If the amount of the cyan-containing vinyl monomer unit is less than 5 mass%, sometimes the effect of improving the chemical resistance is not obtained, and if it is more than 20 mass%, sometimes the yellow index (YI) of the maleimide-based copolymer becomes high.

[0032] The maleimide monomer that can be used in the maleimide-based copolymer is a monomer for improving the heat resistance of the maleimide-based copolymer, and examples thereof include N-methylmaleimide, N-butylmaleimide, N-cyclohexylmaleimide, and other N-alkylmaleimides; and N-phenylmaleimide, N-chlorophenylmaleimide, N-methylphenylmaleimide, N-methoxyphenylmaleimide, N-tribromophenylmaleimide, and the like. Among them, N-phenylmaleimide, which is excellent in the effect of improving the heat resistance, is preferred. The maleimide monomer can be used alone or in combination of two or more. In order to make the maleimide-based copolymer contain the maleimide monomer unit, for example, a raw material composed of the maleimide monomer is copolymerized with other monomers. Alternatively, a raw material composed of the unsaturated dicarboxylic acid monomer unit can be copolymerized with other monomers, and the resulting copolymer can be imidized with ammonia or a primary amine.

[0033] The amount of the maleimide monomer unit contained in 100 mass% of the maleimide-based copolymer is preferably 30 to 50 mass%, more preferably 37 to 45 mass%. Specifically, for example, 30, 35, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50 mass%, or a range between any two of the values exemplified herein can be used. If the amount of the maleimide monomer unit is less than 30 mass%, sometimes the effect of improving the heat resistance is not obtained, and if it is more than 50 mass%, sometimes the impact strength of the maleimide-based copolymer decreases.

[0034] Within a range not impeding the effects of the present application, the maleimide-based copolymer can be copolymerized with a copolymerizable monomer other than the aromatic vinyl monomer, the cyan-containing vinyl monomer, and the maleimide monomer. As the monomer copolymerizable with the maleimide-based copolymer, unsaturated dicarboxylic anhydride monomers such as maleic anhydride, itaconic anhydride, citraconic anhydride, aconitic anhydride, and the like; acrylate monomers such as methyl acrylate, ethyl acrylate, butyl acrylate, and the like; methacrylate monomers such as methyl methacrylate, ethyl methacrylate, and the like; vinyl carboxylic acid monomers such as acrylic acid, methacrylic acid, and the like; acrylamide and methacrylamide, and the like can be used. The monomer copolymerizable with the maleimide-based copolymer can be used alone or in combination of two or more.

[0035] As the monomer copolymerizable with the maleimide-based copolymer, an unsaturated dicarboxylic anhydride monomer is preferable. By containing 0.5% by mass or more of the unsaturated dicarboxylic anhydride monomer unit in 100% by mass of the maleimide-based copolymer, the unsaturated dicarboxylic acid unit reacts with other polymers having an amino group or an alcohol group terminal, and the effect as a compatibilizer is obtained. If the unsaturated dicarboxylic anhydride monomer unit is 10% by mass or less, the heat resistance is excellent, and thus it is preferable, and if the unsaturated dicarboxylic anhydride monomer unit is 5% by mass or less, the heat resistance is more excellent, and thus it is more preferable. Specifically, for example, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 2, 3, 4, 5, 6, 7, 8, 9, 10 parts by mass, or a range between any two of the values exemplified herein can be used.

[0036] The yellow index (YI) of the maleimide-based copolymer is preferably 0.5 to 3.5, and more preferably 2.0 to 3.0. Specifically, for example, 0.5, 1.0, 1.5, 2.0, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, or a range between any two of the values exemplified herein can be used.

[0037] The yellow index of the maleimide-based copolymer can be adjusted, for example, by the weight average molecular weight of the maleimide-based copolymer. The yellow index can be decreased by decreasing the weight average molecular weight of the maleimide-based copolymer, but if the yellow index is less than 0.5, the heat resistance of the maleimide-based copolymer decreases. In addition, the yellow index can be increased by increasing the weight average molecular weight of the maleimide-based copolymer, but if the yellow index is more than 3.5, the flowability of the maleimide-based copolymer decreases. Furthermore, the yellow index can also be adjusted by adjusting the amount of the aromatic vinyl monomer unit or the cyano-containing vinyl monomer unit contained in the maleimide-based copolymer, and the amount of the residual maleimide monomer.

[0038] The yellow index (YI) of the maleimide-based copolymer is a value determined according to JIS K-7373 in the following procedure.

[0039] The maleimide-based copolymer 1 g was dissolved in 25 mL of tetrahydrofuran. After dissolution, it was transferred to a square cell for measurement. The color difference was calculated using a square cell of the tetrahydrofuran solution as a blank under the conditions of a temperature of 23°C and a humidity of 50%, using a transmission method with a D65 light source using CIE standards, and the value was used as the yellow index.

[0040] Apparatus name: SE7700 Spectrocolorimeter (manufactured by Nippon Denshoku Industries Co., Ltd.)

[0041] Measurement cell: A02277A 10 x 36 x 55H square cell 2-side transmission (manufactured by Nippon Densho Co., Ltd.)

[0042] The melt flow rate of the maleimide-based copolymer is preferably 25 to 90 g / 10 minutes, more preferably 65 to 80 g / 10 minutes. Specifically, it is, for example, 25, 30, 35, 40, 45, 50, 55, 60, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 80, 85, 90 g / 10 minutes, and can also be a range between any two of the values exemplified here. If it is less than 25 g / 10 minutes, the flowability of the mixed resin sometimes decreases, and if it is more than 90 g / 10 minutes, the impact resistance sometimes decreases. The melt flow rate is a value determined under the conditions of 265°C and 10 kg according to JIS K-7210.

[0043] The amount of residual maleimide monomer contained in the maleimide-based copolymer is preferably less than 300 ppm, more preferably less than 200 ppm. If the amount of residual maleimide monomer is 300 ppm or more, the yellow index (YI) of the obtained maleimide-based copolymer sometimes becomes high.

[0044] The amount of residual maleimide monomer is a value determined under the conditions described below.

[0045] Apparatus name: Gas chromatograph GC-2010 (manufactured by Shimadzu Corporation)

[0046] Column: Capillary column DB-5ms (manufactured by Agilent Technologies, Inc.)

[0047] Temperature: Inlet 280°C, detector 280°C

[0048] The temperature rise analysis was performed at a column temperature of 80°C (initial).

[0049] (Conditions for temperature rise analysis) 80°C: held for 12 minutes

[0050] 80 to 280°C: temperature rise at 20°C / minute for 10 minutes

[0051] 280°C: held for 10 minutes

[0052] Detector: FID

[0053] Procedure: 0.5 g of the maleimide-based copolymer was dissolved in 5 ml of 1,2-dichloroethane solution (0.014 g / L) containing undecane (internal standard). Thereafter, 5 ml of n-hexane was added, and the mixture was shaken for 10 to 15 minutes with a shaker to precipitate the insoluble component (copolymer component). The supernatant was injected into a gas chromatograph in the state where the insoluble component was precipitated. The quantitative value was calculated from the peak area of the maleimide monomer obtained using the coefficient obtained from the internal standard.

[0054] The weight average molecular weight of the maleimide-based copolymer is 50,000 to 110,000, preferably 70,000 to 100,000. Specifically, it is, for example, 50,000, 60,000, 70,000, 80,000, 90,000, 100,000, 110,000, or a range between any two of these values exemplified herein. If the weight average molecular weight is less than 50,000, the impact resistance is reduced, and if it is more than 110,000, the flowability is reduced.

[0055] The weight average molecular weight is a polystyrene-converted value measured by gel permeation chromatography (GPC) under the following conditions.

[0056] Apparatus name: SYSTEM-21 Shodex (manufactured by Showa Denko K.K.)

[0057] Column: PL gel MIXED-B (manufactured by Polymer Laboratories) 3 in series

[0058] Temperature: 40°C

[0059] Detection: differential refractive index

[0060] Solvent: tetrahydrofuran

[0061] Concentration: 2 mass%

[0062] The calibration curve was prepared using standard polystyrene (PS) (manufactured by Polymer Laboratories).

[0063] To adjust the weight average molecular weight of the maleimide-based copolymer, there are known methods of adding a chain transfer agent during the preparation of the copolymer or increasing the amount of the initiator, or methods of thermally decomposing the obtained copolymer to reduce the molecular weight.

[0064] From the viewpoint of effectively improving the heat resistance of the resin to be mixed and kneaded, such as ABS resin or ASA resin, the midpoint glass transition temperature (Tmg) of the maleimide-based copolymer is preferably 165 to 200°C, more preferably 170 to 200°C. Specifically, it is, for example, 165, 166, 167, 168, 169, 170, 171, 172, 173, 174, 175, 180, 185, 190, 195, 200°C, and can also be a range between any two of the values exemplified herein. If the midpoint glass transition temperature (Tmg) is lower than 165°C, the heat resistance-imparting effect is reduced, and if it is higher than 200°C, the impact resistance and the kneadability are reduced.

[0065] The midpoint glass transition temperature (Tmg) is a value measured according to JIS K-7121 under the following measurement conditions.

[0066] Apparatus name: Differential Scanning Calorimeter Robot DSC6200 (manufactured by Shimadzu Corporation)

[0067] Ramp rate: 10°C / min

[0068] To adjust the midpoint glass transition temperature (Tmg) of the maleimide-based copolymer, it is sufficient to increase the content of the maleimide monomer unit or to copolymerize a monomer having a high midpoint glass transition temperature (Tmg).

[0069] The polymerization method of the maleimide-based copolymer is, for example, solution polymerization, bulk polymerization, or the like. From the viewpoint that a more uniform maleimide-based copolymer can be obtained by performing the polymerization while adding a monomer batchwise or the like, solution polymerization is preferred. From the viewpoint that by-products are less likely to be generated and the adverse effects are small, the solvent for solution polymerization is preferably non-polymerizable. For example, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and phenyl ethyl ketone; ethers such as tetrahydrofuran and 1,4-dioxane; aromatic hydrocarbons such as benzene, toluene, xylene, and chlorobenzene; N,N-dimethylformamide, dimethyl sulfoxide, N-methyl-2-pyrrolidone, and the like. From the viewpoint of the ease of removal of the solvent when the maleimide-based copolymer is recovered by devolatilization, methyl ethyl ketone and methyl isobutyl ketone are preferred. As for the polymerization process, continuous polymerization, batch (batchwise) polymerization, and semi-batch polymerization can all be used.

[0070] The method for producing the maleimide-based copolymer is not particularly limited, and radical polymerization is preferably used to obtain the same, and the polymerization temperature is preferably in the range of 80 to 150°C. The polymerization initiator is not particularly limited, and for example, known azo compounds such as azobisisobutyronitrile, azobiscyclohexanecarbonitrile, azobisdimethylpropionitrile, and azobisdimethylbutyronitrile; known organic peroxides such as benzoyl peroxide, t-butyl peroxybenzoate, 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane, t-butyl peroxyisopropylmonocarbonate, t-butyl peroxy-2-ethylhexanoate, di-t-butyl peroxide, dicumyl peroxide, and ethyl 3,3-di(t-butylperoxy)butyrate can be used, and one of these or two or more of these can be used in combination. From the viewpoint of the reaction rate and the polymerization rate of the polymerization, an azo compound or an organic peroxide having a half-life of 70 to 120°C for 10 hours is preferably used. The amount of the polymerization initiator used is not particularly limited, and 0.1 to 1.5% by mass, and further preferably 0.1 to 1.0% by mass, relative to 100% by mass of the total monomer units, is preferably used. If the amount of the polymerization initiator used is 0.1% by mass or more, a sufficient polymerization rate can be obtained, and thus this is preferable. If the amount of the polymerization initiator used is 1.5% by mass or less, the polymerization rate can be controlled, and thus the reaction can be easily controlled, and the target molecular weight can be easily obtained.

[0071] The production of the maleimide-based copolymer can use a chain transfer agent. The chain transfer agent used is not particularly limited, and for example, n-octyl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan, α-methylstyrene dimer, ethyl mercaptoacetate, limonene, and oil pine can be used. The amount of the chain transfer agent used is not particularly limited as long as the target molecular weight can be obtained, and 0.01 to 0.8% by mass, and further preferably 0.1 to 0.5% by mass, relative to 100% by mass of the total monomer units, is preferably used. The amount of the chain transfer agent used is 0.01 to 0.8% by mass, and the target molecular weight can be easily obtained.

[0072] The method for introducing the maleimide monomer unit of the maleimide-based copolymer is not particularly limited, and for example, a method in which a maleimide monomer, an aromatic vinyl monomer, and a cyano-containing vinyl monomer are copolymerized (direct method); and a method in which an unsaturated dicarboxylic anhydride, an aromatic vinyl monomer, and a cyano-containing vinyl monomer are polymerized in advance, and then the unsaturated dicarboxylic anhydride group is reacted with ammonia or a primary amine to convert the unsaturated dicarboxylic anhydride group into a maleimide monomer unit (post-imidization method) can be used. The post-imidization method can further reduce the amount of residual maleimide monomer in the copolymer, and thus this is preferable.

[0073] As the primary amine used in the post-imidization method, there are, for example, methylamine, ethylamine, n-propylamine, isopropylamine, n-butylamine, n-pentylamine, n-hexylamine, n-octylamine, cyclohexylamine, decylamine, and the like alkylamines, and chloro- or bromo-substituted alkylamines, aniline, toluidine, naphthylamine, and the like aromatic amines, among which aniline and cyclohexylamine are preferred. These primary amines can be used alone or in combination of two or more. The amount of the primary amine to be added is not particularly limited, and is preferably 0.7 to 1.1 mol equivalents, and further preferably 0.85 to 1.05 mol equivalents, relative to the unsaturated dicarboxylic anhydride group. If it is 0.7 mol equivalents or more relative to the unsaturated dicarboxylic anhydride monomer unit in the maleimide-based copolymer, the thermal stability is good, and thus is preferred. In addition, if it is 1.1 mol equivalents or less, the amount of the primary amine remaining in the maleimide-based copolymer is reduced, and thus is preferred.

[0074] When the maleimide monomer unit is introduced by the post-imidization method, a catalyst can be used. In the reaction of ammonia or a primary amine with the unsaturated dicarboxylic anhydride group, and particularly the reaction of conversion from the unsaturated dicarboxylic anhydride group to the maleimide group, the catalyst can promote the dehydration ring closure reaction. The kind of the catalyst is not particularly limited, and for example, a tertiary amine can be used. As the tertiary amine, there is no particular limitation, and for example, trimethylamine, triethylamine, tripropylamine, tributylamine, N,N-dimethylaniline, N,N-diethylaniline, and the like can be mentioned. The amount of the tertiary amine to be added is not particularly limited, and is preferably 0.01 mol equivalents or more, relative to the unsaturated dicarboxylic anhydride group. The temperature of the imidization reaction in the present application is preferably 100 to 250°C, and further preferably 120 to 200°C. If the temperature of the imidization reaction is 100°C or higher, the reaction rate is fast enough, and thus is preferred from the viewpoint of productivity. If the temperature of the imidization reaction is 250°C or lower, the thermal degradation of the maleimide-based copolymer leading to the decrease in properties can be suppressed, and thus is preferred.

[0075] When polymerization is performed by the post-imidization method, the aromatic vinyl monomer, the cyano-containing vinyl monomer, and the unsaturated dicarboxylic anhydride monomer can all be fed at the initial stage of polymerization to be polymerized. However, since the aromatic vinyl monomer and the unsaturated dicarboxylic anhydride monomer have strong alternating copolymerizability, the aromatic vinyl monomer and the unsaturated dicarboxylic anhydride monomer are consumed at the initial stage of polymerization, and a copolymer having a large amount of the cyano-containing vinyl monomer unit can be easily produced at the later stage of polymerization. As a result, the hue of the obtained maleimide-based copolymer can be deteriorated, or the composition distribution can be large, and the compatibility at the time of kneading mixing with an ABS resin or the like can be poor, and thus the properties can not be preferred. Therefore, in order to obtain a maleimide-based copolymer having a good hue and a small composition distribution, it is preferred to perform the following procedures.

[0076] Initial polymerization step: The entire amount of the cyano-containing vinyl monomer, 10 to 90% by mass of the aromatic vinyl monomer, and 0 to 30% by mass of the unsaturated dicarboxylic anhydride monomer are mixed, and the copolymerization is started at the initial stage of polymerization.

[0077] Middle stage polymerization step: The remaining amount of the aromatic vinyl monomer and the remaining amount of the unsaturated dicarboxylic anhydride monomer are added in batches or continuously, while the copolymerization is continued.

[0078] Final stage polymerization step: After the addition of the unsaturated dicarboxylic anhydride monomer is completed, the polymerization is performed by adding more than 1 / 10 of the amount of the aromatic vinyl monomer added in batches or continuously.

[0079] Imidization step: The obtained aromatic vinyl-cyanated vinyl-unsaturated dicarboxylic anhydride copolymer is imidized with ammonia or a primary amine to obtain a maleimide-based copolymer.

[0080] The method for removing the solvent or unreacted monomer and the like used in the solution polymerization from the solution after the solution polymerization of the maleimide-based copolymer is completed or after the post-imidization is completed (devolatilization method) can be a publicly known method. For example, a vacuum devolatilization tank with a heater or a devolatilization extruder with a vent can be used. The maleimide-based copolymer in a molten state after devolatilization can be transferred to a pelletizing step, extruded in a linear shape from a porous die, and processed into a pellet shape using a cold cutting method or an air hot cutting method or an underwater hot cutting method.

[0081] A copolymer other than the maleimide-based copolymer, which is a copolymer containing a cyanated vinyl monomer unit and an aromatic vinyl monomer unit, can be added to the maleimide-based copolymer to form a maleimide-based copolymer composition. The compatibility with the compounded resin is further improved in the obtained maleimide-based copolymer composition. The amount of the copolymer to be added can be appropriately adjusted by the compounded resin or the like, and for example, the amount of the copolymer to be added is 0 to 20 parts by mass, and preferably 0 to 10 parts by mass, with respect to 100 parts by mass of the maleimide-based copolymer. In one embodiment, the amount of the copolymer to be added can be 0.1 parts by mass or more with respect to 100 parts by mass of the maleimide-based copolymer.

[0082] As described above, the maleimide-based copolymer composition can be obtained by further adding a copolymer containing a cyano-containing vinyl monomer unit and an aromatic vinyl monomer unit to the maleimide-based copolymer (post-addition), or can be obtained by allowing the generated copolymer to exist without removing it in the polymerization of the maleimide-based copolymer. The maleimide-based copolymer composition can contain a copolymer having an aromatic vinyl monomer unit, a cyano-containing vinyl monomer unit, and a maleimide monomer unit, and the content of the maleimide monomer unit is less than 30% by mass. In addition, the maleimide-based copolymer composition can also contain a copolymer consisting essentially of a cyano-containing vinyl monomer unit and an aromatic vinyl monomer unit. The maleimide-based copolymer composition can be obtained by allowing such a copolymer to coexist without removing it from the maleimide-based copolymer.

[0083] The maleimide-based copolymer thus obtained can improve the heat resistance of the resulting resin composition by being mixed with various resins. As the various resins, there are no particular limitations, and there are acrylonitrile-butadiene-styrene copolymer resin (ABS resin), acrylonitrile-styrene-acrylic rubber copolymer resin (ASA resin), acrylonitrile-ethylene-propylene rubber-styrene copolymer resin (AES resin), and styrene-acrylonitrile copolymer resin (SAN resin). Since the maleimide-based copolymer has excellent compatibility with these resins, a high heat resistance imparting effect can be obtained. The blending ratio of the maleimide-based copolymer to these resins is preferably 5 to 40% by mass of the maleimide-based copolymer; 60 to 95% by mass of one or two or more kinds of resins selected from the group consisting of ABS resin, ASA resin, AES resin, and SAN resin, and further preferably 10 to 30% by mass of the maleimide-based copolymer; and 70 to 90% by mass of one or two or more kinds of resins selected from the group consisting of ABS resin, ASA resin, AES resin, and SAN resin. If the blending ratio of the maleimide-based copolymer is within this range, an effect of improving the heat resistance of the resin composition can be obtained, and the impact resistance and color tone of the resin composition will not be reduced.

[0084] In addition, in the case where the maleimide-based copolymer composition is used instead of the maleimide-based copolymer, an effect of improving the heat resistance of the resin composition can likewise be obtained, and the impact resistance and color tone of the resin composition will not be reduced.

[0085] There are no particular limitations on the method of mixing the maleimide-based copolymer with various resins, and publicly known melt mixing techniques can be used. As the melt mixing device that can be suitably used, there are single screw extruders, fully intermeshing co-rotating twin screw extruders, fully intermeshing counter-rotating twin screw extruders, non- or partially intermeshing twin screw extruders, and the like, screw extruders, Banbury mixers, kneaders, and mixing rolls.

[0086] When the maleimide-based copolymer is mixed with these resins, a stabilizer, an ultraviolet absorber, a flame retardant, a plasticizer, a lubricant, glass fibers, an inorganic filler, a colorant, an antistatic agent, and the like can be further added.

[0087] In addition, the maleimide-based copolymer composition can be mixed with various resins as with the maleimide-based copolymer, and an additive can be added.

[0088] EXAMPLES

[0089] The following examples are used to illustrate the details, and the present application is not limited to the following examples.

[0090] Example of Production of Maleimide-Based Copolymer (A-1)

[0091] Into a high-pressure vessel having a volume of about 120 liters equipped with a stirrer, 20 parts by mass of styrene, 10 parts by mass of acrylonitrile, 5 parts by mass of maleic anhydride, 0.1 part by mass of t-butyl peroxy-2-ethylhexanoate, 0.5 part by mass of α-methylstyrene dimer, and 12 parts by mass of methyl ethyl ketone were charged, and after the gas phase was replaced with nitrogen, the temperature was raised to 92°C while stirring over 40 minutes. After the temperature was raised to 92°C, 28 parts by mass of styrene, 25 parts by mass of maleic anhydride, and a solution in which 0.22 parts by mass of t-butyl peroxy-2-ethylhexanoate was dissolved in 75 parts by mass of methyl ethyl ketone were continuously added over 7 hours while maintaining the temperature at 92°C. In addition, after the addition of maleic anhydride was completed, 12 parts by mass of styrene was continuously added over 2 hours. After the addition of styrene was completed, the temperature was raised to 120°C, and the polymerization was completed after 1 hour of reaction. Thereafter, 18.6 parts by mass of aniline and 0.3 parts by mass of triethylamine were added to the polymerization solution, and the imidization reaction was performed at 140°C for 7 hours. The imidization reaction solution after the reaction was completed was charged into a vented screw extruder, and the volatile components were removed to obtain a maleimide-based copolymer A-1 in the form of a granule. The results of analysis of the obtained maleimide-based copolymer are shown in Table 1.

[0092] Example of Production of Maleimide-Based Copolymer (A-2)

[0093] A 120-liter autoclave equipped with a stirrer was charged with 20 parts by mass of styrene, 21 parts by mass of acrylonitrile, 5 parts by mass of maleic anhydride, 0.1 part by mass of t-butyl peroxy-2-ethylhexanoate, 0.5 part by mass of α-methylstyrene dimer, 12 parts by mass of methyl ethyl ketone, and the gas phase was replaced with nitrogen. The temperature was raised to 92°C over 40 minutes while stirring. After the temperature was raised, the temperature was maintained at 92°C, and 28 parts by mass of styrene, 26 parts by mass of maleic anhydride, and a solution in which 0.22 parts by mass of t-butyl peroxy-2-ethylhexanoate was dissolved in 75 parts by mass of methyl ethyl ketone were continuously added over 7 hours. Further, after the addition of maleic anhydride was completed, the temperature was raised to 120°C, and the polymerization was completed by reacting for 1 hour. Thereafter, 19.9 parts by mass of aniline and 0.3 parts by mass of triethylamine were added to the polymerization solution, and the imidization reaction was carried out at 140°C for 7 hours. The imidization reaction solution after the reaction was completed was introduced into a vented screw extruder, and the volatile components were removed to obtain a granular maleimide-based copolymer A-2. The analysis results of the obtained maleimide-based copolymer are shown in Table 1.

[0094] Example of production of maleimide-based copolymer (A-3)

[0095] A 120-liter autoclave equipped with a stirrer was charged with 20 parts by mass of styrene, 21 parts by mass of acrylonitrile, 5 parts by mass of maleic anhydride, 0.1 part by mass of t-butyl peroxy-2-ethylhexanoate, 0.5 part by mass of α-methylstyrene dimer, 12 parts by mass of methyl ethyl ketone, and the gas phase was replaced with nitrogen. The temperature was raised to 92°C over 40 minutes while stirring. After the temperature was raised, the temperature was maintained at 92°C, and 28 parts by mass of styrene, 26 parts by mass of maleic anhydride, and a solution in which 0.22 parts by mass of t-butyl peroxy-2-ethylhexanoate was dissolved in 75 parts by mass of methyl ethyl ketone were continuously added over 7 hours. Further, after the addition of maleic anhydride was completed, the temperature was raised to 120°C, and the polymerization was completed by reacting for 1 hour. Thereafter, 19.9 parts by mass of aniline and 0.3 parts by mass of triethylamine were added to the polymerization solution, and the imidization reaction was carried out at 140°C for 7 hours. The imidization reaction solution after the reaction was completed was introduced into a vented screw extruder, and the volatile components were removed to obtain a granular maleimide-based copolymer A-2. The analysis results of the obtained maleimide-based copolymer are shown in Table 1.

[0096] Example of production of maleimide-based copolymer (A-4)

[0097] A 120-liter autoclave equipped with a stirrer was charged with 20 parts by mass of styrene, 10 parts by mass of acrylonitrile, 5 parts by mass of maleic anhydride, 0.1 part by mass of t-butyl peroxy-2-ethylhexanoate, 0.2 part by mass of α-methylstyrene dimer, and 12 parts by mass of methyl ethyl ketone. After the gas phase was replaced with nitrogen, the temperature was raised to 92°C over 40 minutes while stirring. After the temperature was raised, the temperature was maintained at 92°C, and 28 parts by mass of styrene and 25 parts by mass of maleic anhydride were continuously added over 7 hours. In addition, after the addition of maleic anhydride was completed, 12 parts by mass of styrene was continuously added over 2 hours. After the addition of styrene was completed, the temperature was raised to 120°C, and the polymerization was completed after 1 hour of reaction. Thereafter, 18.7 parts by mass of aniline and 0.3 part by mass of triethylamine were added to the polymerization solution, and the imidization reaction was carried out at 140°C for 7 hours. The imidization reaction solution after the reaction was completed was introduced into a vented screw extruder, and the volatile components were removed to obtain a granular maleimide-based copolymer A-4. The analysis results of the obtained maleimide-based copolymer are shown in Table 1.

[0098] <Example of production of maleimide-based copolymer (A-5)>

[0099] A 120-liter autoclave equipped with a stirrer was charged with 20 parts by mass of styrene, 10 parts by mass of acrylonitrile, 5 parts by mass of maleic anhydride, 0.1 part by mass of t-butyl peroxy-2-ethylhexanoate, 0.5 part by mass of α-methylstyrene dimer, and 12 parts by mass of methyl ethyl ketone. After the gas phase was replaced with nitrogen, the temperature was raised to 92°C over 40 minutes while stirring. After the temperature was raised, the temperature was maintained at 92°C, and 28 parts by mass of styrene and 25 parts by mass of maleic anhydride were continuously added over 7 hours. In addition, after the addition of maleic anhydride was completed, 12 parts by mass of styrene was continuously added over 2 hours. After the addition of styrene was completed, the temperature was raised to 120°C, and the polymerization was completed after 1 hour of reaction. Thereafter, 11.9 parts by mass of aniline and 0.2 part by mass of triethylamine were added to the polymerization solution, and the imidization reaction was carried out at 140°C for 7 hours. The imidization reaction solution after the reaction was completed was introduced into a vented screw extruder, and the volatile components were removed to obtain a granular maleimide-based copolymer A-5. The analysis results of the obtained maleimide-based copolymer are shown in Table 1.

[0100] <Example of production of maleimide-based copolymer (A-6)>

[0101] A 120-liter autoclave equipped with a stirrer was charged with 20 parts by mass of styrene, 10 parts by mass of acrylonitrile, 5 parts by mass of maleic anhydride, 0.1 part by mass of t-butyl peroxy-2-ethylhexanoate, 0.5 part by mass of α-methylstyrene dimer, and 12 parts by mass of methyl ethyl ketone. After the gas phase was replaced with nitrogen, the temperature was raised to 92°C over 40 minutes while stirring. After the temperature was raised, the temperature was maintained at 92°C, and 28 parts by mass of styrene and 25 parts by mass of maleic anhydride were continuously added over 7 hours. In addition, a solution in which 0.22 parts by mass of t-butyl peroxy-2-ethylhexanoate was dissolved in 75 parts by mass of methyl ethyl ketone was continuously added over 7 hours. Furthermore, 12 parts by mass of styrene was continuously added over 2 hours after the addition of maleic anhydride was completed. After the addition of styrene was completed, the temperature was raised to 120°C, and the polymerization was completed after 1 hour of reaction. Thereafter, 23.0 parts by mass of aniline and 0.3 parts by mass of triethylamine were added to the polymerization solution, and the imidization reaction was carried out at 140°C for 7 hours. The imidization reaction solution after the reaction was completed was introduced into a vented screw extruder, and the volatile components were removed to obtain a granular maleimide-based copolymer A-6. The analysis results of the obtained maleimide-based copolymer are shown in Table 1.

[0102] Example of production of maleimide-based copolymer (A-7)

[0103] A 120-liter autoclave equipped with a stirrer was charged with 20 parts by mass of styrene, 10 parts by mass of acrylonitrile, 5 parts by mass of maleic anhydride, 0.1 part by mass of t-butyl peroxy-2-ethylhexanoate, 0.5 part by mass of α-methylstyrene dimer, and 12 parts by mass of methyl ethyl ketone. After the gas phase was replaced with nitrogen, the temperature was raised to 92°C over 40 minutes while stirring. After the temperature was raised, the temperature was maintained at 92°C, and 28 parts by mass of styrene and 25 parts by mass of maleic anhydride were continuously added over 7 hours. In addition, a solution in which 0.22 parts by mass of t-butyl peroxy-2-ethylhexanoate was dissolved in 75 parts by mass of methyl ethyl ketone was continuously added over 7 hours. Furthermore, 12 parts by mass of styrene was continuously added over 2 hours after the addition of maleic anhydride was completed. After the addition of styrene was completed, the temperature was raised to 120°C, and the polymerization was completed after 1 hour of reaction. Thereafter, 23.0 parts by mass of aniline and 0.3 parts by mass of triethylamine were added to the polymerization solution, and the imidization reaction was carried out at 140°C for 7 hours. The imidization reaction solution after the reaction was completed was introduced into a vented screw extruder, and the volatile components were removed to obtain a granular maleimide-based copolymer A-6. The analysis results of the obtained maleimide-based copolymer are shown in Table 1.

[0104] Example of production of maleimide-based copolymer (A-7)

[0105] A 120-liter autoclave equipped with a stirrer was charged with 20 parts by mass of styrene, 15 parts by mass of acrylonitrile, 5 parts by mass of maleic anhydride, 0.1 part by mass of t-butyl peroxy-2-ethylhexanoate, 0.5 part by mass of α-methylstyrene dimer, 12 parts by mass of methyl ethyl ketone, and the gas phase was replaced with nitrogen. The temperature was raised to 92°C over 40 minutes while stirring. After the temperature was raised, the temperature was maintained at 92°C, and 28 parts by mass of styrene, 28 parts by mass of maleic anhydride, and a solution in which 0.22 parts by mass of t-butyl peroxy-2-ethylhexanoate was dissolved in 75 parts by mass of methyl ethyl ketone were continuously added over 7 hours. In addition, 4 parts by mass of styrene was continuously added over 2 hours after the addition of maleic anhydride was completed. After the addition of styrene was completed, the temperature was raised to 120°C, and the polymerization was completed after 1 hour of reaction. Thereafter, 20.1 parts by mass of aniline and 0.3 parts by mass of triethylamine were added to the polymerization solution, and the imidization reaction was carried out at 140°C for 7 hours. The imidization reaction solution after the reaction was completed was introduced into a vented screw extruder, and the volatile components were removed to obtain a granular maleimide-based copolymer A-8. The analysis results of the obtained maleimide-based copolymer are shown in Table 1.

[0106] Example of production of maleimide-based copolymer (B-1)

[0107] A 120-liter autoclave equipped with a stirrer was charged with 20 parts by mass of styrene, 15 parts by mass of acrylonitrile, 5 parts by mass of maleic anhydride, 0.1 part by mass of t-butyl peroxy-2-ethylhexanoate, 0.5 part by mass of α-methylstyrene dimer, 12 parts by mass of methyl ethyl ketone, and the gas phase was replaced with nitrogen. The temperature was raised to 92°C over 40 minutes while stirring. After the temperature was raised, the temperature was maintained at 92°C, and 28 parts by mass of styrene, 28 parts by mass of maleic anhydride, and a solution in which 0.22 parts by mass of t-butyl peroxy-2-ethylhexanoate was dissolved in 75 parts by mass of methyl ethyl ketone were continuously added over 7 hours. In addition, 4 parts by mass of styrene was continuously added over 2 hours after the addition of maleic anhydride was completed. After the addition of styrene was completed, the temperature was raised to 120°C, and the polymerization was completed after 1 hour of reaction. Thereafter, 20.1 parts by mass of aniline and 0.3 parts by mass of triethylamine were added to the polymerization solution, and the imidization reaction was carried out at 140°C for 7 hours. The imidization reaction solution after the reaction was completed was introduced into a vented screw extruder, and the volatile components were removed to obtain a granular maleimide-based copolymer A-8. The analysis results of the obtained maleimide-based copolymer are shown in Table 1.

[0108] Example of production of maleimide-based copolymer (B-2)

[0109] Into a high-pressure vessel of about 120 liters equipped with a stirrer, 20 parts by mass of styrene, 10 parts by mass of acrylonitrile, 6 parts by mass of maleic anhydride, 0.1 part by mass of t-butyl peroxy-2-ethylhexanoate, 12 parts by mass of methyl ethyl ketone were charged, and after the gas phase was replaced with nitrogen, the temperature was raised to 92°C over 40 minutes while stirring. After the temperature was raised, the temperature was maintained at 92°C, and 28 parts by mass of styrene, 24 parts by mass of maleic anhydride, and a solution in which 0.22 parts by mass of t-butyl peroxy-2-ethylhexanoate was dissolved in 75 parts by mass of methyl ethyl ketone were continuously added over 7 hours. In addition, 12 parts by mass of styrene was continuously added over 2 hours after the addition of maleic anhydride was completed. After the addition of styrene was completed, the temperature was raised to 120°C, and the polymerization was completed by reacting for 1 hour. Thereafter, 18.9 parts by mass of aniline and 0.3 parts by mass of triethylamine were added to the polymerization solution, and the imidization reaction was carried out at 140°C for 7 hours. The imidization reaction solution after the reaction was completed was charged into a vented screw extruder, and the volatile components were removed to obtain a granular maleimide-based copolymer B-2. The analysis results of the obtained maleimide-based copolymer are shown in Table 2.

[0110] <Example of production of maleimide-based copolymer (B-3)>

[0111] Into a high-pressure vessel of about 120 liters equipped with a stirrer, 20 parts by mass of styrene, 10 parts by mass of acrylonitrile, 6 parts by mass of maleic anhydride, 0.1 part by mass of t-butyl peroxy-2-ethylhexanoate, 12 parts by mass of methyl ethyl ketone were charged, and after the gas phase was replaced with nitrogen, the temperature was raised to 92°C over 40 minutes while stirring. After the temperature was raised, the temperature was maintained at 92°C, and 28 parts by mass of styrene, 24 parts by mass of maleic anhydride, and a solution in which 0.22 parts by mass of t-butyl peroxy-2-ethylhexanoate was dissolved in 75 parts by mass of methyl ethyl ketone were continuously added over 7 hours. In addition, 12 parts by mass of styrene was continuously added over 2 hours after the addition of maleic anhydride was completed. After the addition of styrene was completed, the temperature was raised to 120°C, and the polymerization was completed by reacting for 1 hour. Thereafter, 18.9 parts by mass of aniline and 0.3 parts by mass of triethylamine were added to the polymerization solution, and the imidization reaction was carried out at 140°C for 7 hours. The imidization reaction solution after the reaction was completed was charged into a vented screw extruder, and the volatile components were removed to obtain a granular maleimide-based copolymer B-2. The analysis results of the obtained maleimide-based copolymer are shown in Table 2.

[0112] <Example of production of maleimide-based copolymer (B-4)>

[0113] A 120-liter autoclave equipped with a stirrer was charged with 20 parts by mass of styrene, 21 parts by mass of acrylonitrile, 8 parts by mass of maleic anhydride, 0.1 part by mass of t-butyl peroxy-2-ethylhexanoate, 0.025 part by mass of α-methylstyrene dimer, 12 parts by mass of methyl ethyl ketone, and the gas phase was replaced with nitrogen. The temperature was raised to 92°C over 40 minutes while stirring. After the temperature was raised, the temperature was maintained at 92°C, and 28 parts by mass of styrene, 23 parts by mass of maleic anhydride, and a solution in which 0.22 parts by mass of t-butyl peroxy-2-ethylhexanoate was dissolved in 75 parts by mass of methyl ethyl ketone were continuously added over 7 hours. Further, after the addition of maleic anhydride, the temperature was raised to 120°C, and the polymerization was completed after 1 hour of reaction. Thereafter, 19.2 parts by mass of aniline and 0.3 parts by mass of triethylamine were added to the polymerization solution, and the imidization reaction was carried out at 140°C for 7 hours. The imidization reaction solution after the reaction was completed was introduced into a vented screw extruder, and the volatile components were removed to obtain a granular maleimide-based copolymer B-4. The results of the analysis of the obtained maleimide-based copolymer are shown in Table 2.

[0114] Example of production of maleimide-based copolymer (B-5)

[0115] A 120-liter autoclave equipped with a stirrer was charged with 20 parts by mass of styrene, 21 parts by mass of acrylonitrile, 8 parts by mass of maleic anhydride, 0.1 part by mass of t-butyl peroxy-2-ethylhexanoate, 0.025 part by mass of α-methylstyrene dimer, 12 parts by mass of methyl ethyl ketone, and the gas phase was replaced with nitrogen. The temperature was raised to 92°C over 40 minutes while stirring. After the temperature was raised, the temperature was maintained at 92°C, and 28 parts by mass of styrene, 23 parts by mass of maleic anhydride, and a solution in which 0.22 parts by mass of t-butyl peroxy-2-ethylhexanoate was dissolved in 75 parts by mass of methyl ethyl ketone were continuously added over 7 hours. Further, after the addition of maleic anhydride, the temperature was raised to 120°C, and the polymerization was completed after 1 hour of reaction. Thereafter, 19.2 parts by mass of aniline and 0.3 parts by mass of triethylamine were added to the polymerization solution, and the imidization reaction was carried out at 140°C for 7 hours. The imidization reaction solution after the reaction was completed was introduced into a vented screw extruder, and the volatile components were removed to obtain a granular maleimide-based copolymer B-4. The results of the analysis of the obtained maleimide-based copolymer are shown in Table 2.

[0116] Example of production of maleimide-based copolymer (B-5)

[0117] A 120-liter autoclave equipped with a stirrer was charged with 20 parts by mass of styrene, 10 parts by mass of acrylonitrile, 10 parts by mass of maleic anhydride, 0.1 part by mass of t-butyl peroxy-2-ethylhexanoate, 0.025 part by mass of α-methylstyrene dimer, and 12 parts by mass of methyl ethyl ketone. After the gas phase was replaced with nitrogen, the temperature was raised to 92°C over 40 minutes while stirring. After the temperature was raised, the temperature was maintained at 92°C, and 28 parts by mass of styrene and 20 parts by mass of maleic anhydride were continuously added over 7 hours. In addition, a solution in which 0.22 parts by mass of t-butyl peroxy-2-ethylhexanoate was dissolved in 75 parts by mass of methyl ethyl ketone was continuously added over 7 hours. Furthermore, 12 parts by mass of styrene was continuously added over 2 hours after the addition of maleic anhydride was completed. After the addition of styrene was completed, the temperature was raised to 120°C, and the polymerization was completed after 1 hour of reaction. Thereafter, 18.7 parts by mass of aniline and 0.3 parts by mass of triethylamine were added to the polymerization solution, and the imidization reaction was carried out at 140°C for 7 hours. The imidization reaction solution after the reaction was completed was introduced into a vented screw extruder, and the volatile components were removed to obtain a granular maleimide-based copolymer B-6. The analysis results of the obtained maleimide-based copolymer are shown in Table 2.

[0118] Example of Production of Maleimide-Based Copolymer (B-7)

[0119] A 120-liter autoclave equipped with a stirrer was charged with 20 parts by mass of styrene, 22 parts by mass of acrylonitrile, 13 parts by mass of maleic anhydride, 0.1 part by mass of t-butyl peroxy-2-ethylhexanoate, 0.5 part by mass of α-methylstyrene dimer, and 12 parts by mass of methyl ethyl ketone. After the gas phase was replaced with nitrogen, the temperature was raised to 92°C over 40 minutes while stirring. After the temperature was raised, the temperature was maintained at 92°C, and 27 parts by mass of styrene and 18 parts by mass of maleic anhydride were continuously added over 7 hours. In addition, a solution in which 0.22 parts by mass of t-butyl peroxy-2-ethylhexanoate was dissolved in 75 parts by mass of methyl ethyl ketone was continuously added over 7 hours. Furthermore, the temperature was raised to 120°C after the addition of maleic anhydride was completed, and the polymerization was completed after 1 hour of reaction. Thereafter, 19.2 parts by mass of aniline and 0.3 parts by mass of triethylamine were added to the polymerization solution, and the imidization reaction was carried out at 140°C for 7 hours. The imidization reaction solution after the reaction was completed was introduced into a vented screw extruder, and the volatile components were removed to obtain a granular maleimide-based copolymer B-7. The analysis results of the obtained maleimide-based copolymer are shown in Table 2.

[0120] Table 1

[0121]

[0122] Table 2

[0123]

[0124] (weight average molecular weight)

[0125] The weight average molecular weight is a polystyrene-converted value measured by gel permeation chromatography (GPC) under the following conditions.

[0126] Apparatus name: SYSTEM-21 Shodex (manufactured by Showa Denko K.K.)

[0127] Column: PL gel MIXED-B (manufactured by Polymer Laboratories) 3 in series

[0128] Temperature: 40°C

[0129] Detection: Differential refractive index

[0130] Solvent: Tetrahydrofuran

[0131] Concentration: 2 mass%

[0132] Standard curve: Drawn using standard polystyrene (PS) (manufactured by Polymer Laboratories).

[0133] (Melt flow rate)

[0134] Measured according to JIS K-7210 using the following apparatus and measurement conditions.

[0135] Apparatus name: No. 120 melt flow rate measuring apparatus (manufactured by Yasuda Seiki Mfg. Corp.)

[0136] Temperature: 265°C

[0137] Load: 98 N

[0138] (Midpoint glass transition temperature (Tmg))

[0139] Measured according to JIS K-7121 using the following apparatus and measurement conditions.

[0140] Apparatus name: Robot DSC6200 (manufactured by SII Technologies Inc.)

[0141] Temperature increase rate: 10°C / minute

[0142] (Residual maleimide monomer amount)

[0143] After 0.5 g of each maleimide-based copolymer obtained above was dissolved in 5 ml of a 1,2-dichloroethane solution (0.014 g / L) containing undecane (internal standard), 5 ml of n-hexane was added and the mixture was shaken with a shaker for 10 to 15 minutes to precipitate the insoluble component (copolymer component). The supernatant was injected into a gas chromatograph in the state where the insoluble component was precipitated. The coefficient was calculated from the peak area of the maleimide monomer obtained based on the internal standard, and the quantitative value was calculated using this coefficient.

[0144] Instrument Name: Gas Chromatograph GC-2010 (Manufactured by Shimadzu Corporation)

[0145] Column: DB-5ms capillary column (manufactured by Agilent Technologies, Inc.)

[0146] Temperature: Inlet 280℃, Detector 280℃

[0147] Temperature analysis was performed at an initial column temperature of 80°C.

[0148] (Temperature analysis conditions) 80℃: Hold for 12 minutes

[0149] 80~280℃: Increase temperature at 20℃ / min for 10 minutes

[0150] 280℃: Maintain for 10 minutes

[0151] Detector: FID

[0152] (Yellow Index (YI))

[0153] The determination was made according to JIS K-7373. The specific steps are as follows.

[0154] 1 g of each of the maleimide copolymers obtained above was dissolved in 25 mL of tetrahydrofuran. After dissolution, the solution was transferred to a square cell for measurement. Under conditions of 23°C and 50% humidity, the color difference was calculated using a CIE standard D65 light source via transmission method, with the square cell containing the tetrahydrofuran solution as a blank. This value was used as the yellow index.

[0155] Device Name: SE7700 Spectrocolorimeter (manufactured by Nippon Denshoku Kogyo Co., Ltd.)

[0156] Square cell: A02277A 10×36×55H Square cell with two-sided transmission

[0157] <Example · Comparative Example>

[0158] Examples 1-8 and Comparative Examples 1-8 (Mixing of maleimide copolymers with ABS resin)

[0159] Maleimide copolymers A-1 to A-12 were mixed with commercially available ABS resin "GR-3000" (manufactured by DENKA Corporation) according to the proportions shown in Tables 3 and 4, and then extruded into granules using a twin-screw extruder (manufactured by Toshiba Machine Co., Ltd., TEM-35B). Test specimens were then made using injection molding machines using these granules, and their various physical properties were measured. The results are shown in Tables 3 and 4.

[0160] Table 3

[0161]

[0162] Table 4

[0163]

[0164] (izod impact strength)

[0165] The test was performed using a notched test piece according to JIS K-7111, with the striking direction being the edge, under conditions of a relative humidity of 50% and an ambient temperature of 23°C. Note that the measuring device used was a digital impact tester manufactured by Toyo Seiki Jiki Kogyo Co., Ltd.

[0166] (vicat softening temperature)

[0167] The test was performed using a 50 method (load of 50 N, temperature increase rate of 50°C / hour) according to JIS K-7206, using a test piece of 10 mm x 10 mm x 4 mm. Note that the measuring device used was an HDT & VSP Test Device manufactured by Toyo Seiki Jiki Kogyo Co., Ltd.

[0168] (melt flow rate)

[0169] The test was performed according to JIS K-7210 under conditions of 220°C and a load of 98 N.

[0170] yellow index (YI)

[0171] The test was performed according to JIS K-7373. The specific procedure was as follows.

[0172] 1 g of each of the test pieces obtained above was dissolved in 25 mL of tetrahydrofuran. After dissolution, it was transferred to a measuring square cell. The color difference was calculated using a transmission method using a D65 light source of the CIE standard, with the square cell of the tetrahydrofuran solution serving as a blank, under conditions of a temperature of 23°C and a humidity of 50%, and the value was taken as the yellow index.

[0173] Device name: SE7700 Spectrocolorimeter (manufactured by Nippon Denshoku Industries Co., Ltd.)

[0174] Square cell: A02277A 10 x 36 x 55H square cell 2-way transmission

[0175] chemical resistance

[0176] The cracking after 23°C for 48 hours was observed using a 1 / 4 ellipse method with a test piece shape of 316 x 20 x 2 mm, a long radius of 250 mm, and a short radius of 150 mm. In order to eliminate the effects of molding strain, the test piece was manufactured by cutting after compression molding of the pellets at 260°C. The chemical used was toluene.

[0177] Note that the critical strain was calculated using the following formula.

[0178] ε = b / 2a 2 {1 - (a 2 -b 2 ) X 2 / a 4} 1.5 x t x 100

[0179] Critical strain: ε, long radius: a, short radius: b, specimen thickness: t, cracking point: X The chemical resistance was evaluated according to the critical strain based on the following criteria.

[0180] ◎: 0.8 or more, ○: 0.6 to 0.7, Δ: 0.3 to 0.5, X: 0.2 or less

[0181] As shown in Examples 1 to 8, the maleimide-based copolymers of A-1 to A-8 of the present application achieved a high midpoint glass transition temperature (Tmg) and a high melt flow rate by reducing the molecular weight without reducing the content of the maleimide monomer unit in the composition. However, if the molecular weight is reduced by more than a certain amount, as shown in Comparative Example 7, a decrease in chemical resistance was observed. The maleimide-based copolymers of B-1 to B-7 that do not satisfy the range of the present application are excluded from the scope of the claims of the present application, and the impact resistance, flowability, and chemical resistance of the resin compositions of Comparative Examples 1 to 7 obtained by mixing and kneading these maleimide-based copolymers with ABS resins were all poor.

[0182] Industrial applicability

[0183] The maleimide-based copolymers of the present application can obtain a resin composition having excellent balance of chemical resistance, heat resistance, impact resistance, and flowability by mixing and kneading with compatible ABS resins, ASA resins, AES resins, and SAN resins. Furthermore, the flowability of the mixed resins can be improved, and thus the speed of molding can be increased, and the production speed can be increased. In addition, since the yellow index (YI) of the molded product can be reduced, the product can be used for white applications.

Claims

1. A maleimide-based copolymer containing an aromatic vinyl monomer unit, a cyano-containing vinyl monomer unit, and a maleimide monomer unit, the content of the cyano-containing vinyl monomer unit in 100 mass% of the maleimide-based copolymer being 7 to 20 mass%, the amount of residual maleimide monomer contained in the maleimide-based copolymer being less than 300 ppm, the weight average molecular weight being 50,000 to 110,000, and the midpoint glass transition temperature measured according to JIS K-7121 being 166°C to 169°C.

2. The maleimide-based copolymer according to claim 1, wherein the yellow index measured according to JIS K-7373 is 0.5 to 3.

5.

3. The maleimide-based copolymer according to claim 1 or 2, wherein the maleimide-based copolymer contains an aromatic vinyl monomer unit 40 to 60 mass%, a cyano-containing vinyl monomer unit 7 to 20 mass%, and a maleimide monomer unit 30 to 50 mass% as monomer units constituting the maleimide-based copolymer.

4. A maleimide-based copolymer composition containing: 100 parts by mass of the maleimide-based copolymer according to any one of claims 1 to 3; and 0 to 20 parts by mass of a copolymer other than the maleimide-based copolymer, 5. A resin composition containing: 5 to 40 mass% of the maleimide-based copolymer according to any one of claims 1 to 3; and 60 to 95 mass% of one or two or more kinds of resins selected from the group consisting of an acrylonitrile-butadiene-styrene copolymer resin, an acrylonitrile-styrene-acrylic rubber copolymer resin, an acrylonitrile-ethylene-propylene rubber-styrene copolymer resin, and a styrene-acrylonitrile copolymer resin.

6. A resin composition containing: 5 to 40 mass% of the maleimide-based copolymer composition according to claim 4; and 60 to 95 mass% of one or two or more kinds of resins selected from the group consisting of an acrylonitrile-butadiene-styrene copolymer resin, an acrylonitrile-styrene-acrylic rubber copolymer resin, an acrylonitrile-ethylene-propylene rubber-styrene copolymer resin, and a styrene-acrylonitrile copolymer resin.

7. An injection-molded body using the resin composition according to claim 5 or 6.

8. The injection-molded body according to claim 7, which is used as an interior or exterior member of an automobile. ​ ​ ​ ​ ​ ​ ​ ​ ​

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