JP6934755B2 - Thermoplastic resin composition and its molded product - Google Patents

Description

The present invention relates to a thermoplastic resin composition and a molded product thereof.

As a method of joining molded products, mechanical joining with screws, bolts, etc., joining with an adhesive such as hot melt, thermal joining by applying heat to melt, typified by hot plate welding, vibration of the joint Vibration welding using the frictional heat generated by the welding, laser welding by irradiating the joint portion with laser light and utilizing the absorption heat generated by the irradiated portion, and the like are known. Recently, hot plate welding, vibration welding, and laser welding have been increasing their usefulness from the viewpoints of reducing the processing process, reducing the weight of the bonded product, and reducing the environmental load.

Examples of molded products that are hot plate welded include automobile lamp housings used for headlamps, rear combination lamps, and the like. As the material of the lamp housing, a styrene resin such as an acrylonitrile-butadiene-styrene copolymer (ABS resin) having good weldability is used. However, with the recent improvement in the performance of automobile lamps, the temperature inside the lamp becomes in a high temperature range, so that a resin having high heat resistance is required as a material for the lamp housing.

As a material for a lamp housing having high heat resistance, a heat-resistant ABS resin and a mixture of a heat-resistant ABS resin and polycarbonate have been proposed. However, with these resins, when the molded product is pulled away from the hot plate, the melted portion of the resin is stretched into a thread and stringing occurs, which adheres to the surface of the molded product such as a lamp lens and a lamp housing. May result in poor appearance.

Further, in the lamp housing, the final product is often partially subjected to secondary processing such as painting, metal deposition, and plating. In order to adapt the lamp housing to secondary processing, the lamp housing needs to have a highly good surface condition (surface appearance).
As described above, the lamp housing is required to have excellent stringing resistance at the time of hot plate welding, have a highly good surface appearance, and have sufficient impact resistance and heat resistance as a lamp housing. There is.

The following materials have been proposed as materials for lamp housings that can improve stringing.
(1) A resin obtained by blending 100 parts by mass of a rubber-reinforced styrene resin with 3 to 30 parts by mass of an α-methylstyrene copolymer having a reduced viscosity of a soluble component of methyl ethyl ketone of 0.1 to 0.4 dL / g. Composition (Patent Document 1).

The following materials have been proposed as materials for lamp housings that can improve the gloss of stringing and vacuum-deposited surfaces.
(2) A rubber polymer having a volume average particle size of 60 to 250 nm and 20 to 98% by mass of an α-methylstyrene copolymer having a reduced viscosity of a soluble component of methyl ethyl ketone of 0.3 to 1.2 dL / g. A resin composition containing 2 to 80% by mass of a graft copolymer obtained by polymerizing a vinyl-based monomer in the presence of (Patent Document 2).

The following materials have been proposed as materials for lamp housings that provide molded products with excellent impact resistance, heat resistance, molded appearance, and weldability.
(3) The gel content is 70% by mass or more, the degree of swelling due to toluene is 5.5 to 30 times, the volume average particle size is 100 to 200 nm, and the ratio of the volume average particle size to the number average particle size. Acrylic containing an acrylic rubber polymer reinforced graft resin obtained by polymerizing a vinyl monomer on an acrylic rubber polymer having a value of less than 1.1 and an α-methylstyrene copolymer. A resin composition in which the content of the rubbery polymer is 10 to 40% by mass in the resin composition and the content of structural units derived from α-methylstyrene is 15 to 45% by mass in the resin composition (Patented). Document 3).

Japanese Unexamined Patent Publication No. 2001-2881 Japanese Unexamined Patent Publication No. 2001-253990 Japanese Unexamined Patent Publication No. 2012-1713

However, in Patent Document 1, since it is determined that the length of the yarn is 0.5 cm or less and there is no stringing, the molded product made of the resin composition of (1) has the temperature of the hot plate and the moisture absorption of the molded product. It cannot be said that there is no stringing when the state changes. Further, it cannot be said that the molded product has sufficient heat resistance depending on the amount of the α-methylstyrene copolymer. Further, Patent Document 1 does not mention the surface appearance of the molded product.
Patent Document 2 does not mention impact resistance, heat resistance, etc. of the molded product made of the resin composition of (2).
The molded product made of the resin composition of (3) cannot satisfy all of the stringiness resistance, surface appearance, impact resistance and heat resistance at the same time at a high level.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to obtain a molded product having excellent stringing resistance at the time of hot plate welding, having a highly good surface appearance, and having sufficient impact resistance and heat resistance as a material for a lamp housing. A plastic resin composition and a molded product thereof are provided.

As a result of diligent studies, the present inventors have obtained heat containing a graft copolymer in which the particle size, acetone-soluble content and its reduced viscosity of the rubber-like polymer are controlled, and a specific amount of α-methylstyrene-based copolymer. It has been found that the above-mentioned problems can be solved by the plastic resin composition, and the present invention has been completed.

The present invention has the following aspects.
<1> It is obtained by polymerizing a vinyl-based polymer (a2) in the presence of a rubber-like polymer (a1) having an average particle size of more than 200 nm and 320 nm or less, and has an acetone-soluble content. With the graft copolymer (A) having a reduced viscosity of 10 to 40% by mass and a reduced viscosity of the acetone-soluble component of 0.3 to 0.8 dL / g; a structural unit derived from α-methylstyrene and a vinyl cyanide type. It is a thermoplastic resin composition containing an α-methylstyrene-based copolymer (B) having a structural unit derived from a monomer; the content of the rubber-like polymer (a1) is the thermoplastic resin composition. 10 to 20% by mass of the product (100% by mass); the content of the α-methylstyrene-based copolymer (B) is 31 to 31% of the thermoplastic resin composition (100% by mass). A thermoplastic resin composition of 80% by mass.
<2> The α-methylstyrene copolymer (B) is a structural unit derived from α-methylstyrene, a structural unit derived from a vinyl cyanide monomer, and an aromatic vinyl monomer (however, however). The thermoplastic resin composition of <1>, which has a structural unit derived from α-methylstyrene) and a structural unit derived from a maleimide-based monomer.
<3> The thermoplastic resin composition of <1> or <2>, wherein the rubbery polymer (a1) has an average particle size of 205 to 250 nm.
<4> The heat according to any one of <1> to <3>, wherein the reduced viscosity of the acetone-soluble component of the α-methylstyrene copolymer (B) is 0.41 to 0.9 dL / g. Plastic resin composition.
<5> A molded product made of the thermoplastic resin composition according to any one of <1> to <4>.

According to the thermoplastic resin composition of the present invention, it is excellent in stringiness resistance at the time of hot plate welding, has a highly good surface appearance, and has sufficient impact resistance and heat resistance as a material for a lamp housing. A molded product can be obtained.
The molded product of the present invention has excellent stringing resistance during hot plate welding, has a highly good surface appearance, and has sufficient impact resistance and heat resistance as a material for a lamp housing.

The definitions of the following terms apply throughout the specification and claims.
The "average particle size" is calculated from the obtained particle size distribution obtained by measuring the particle size distribution based on the volume of the sample using a particle size distribution measuring device.
For "Acetone-soluble content ratio", 2.5 g of a sample was added to 80 mL of acetone, heated and refluxed at 65 to 70 ° C. for 3 hours, and the obtained suspended acetone solution was centrifuged at 14000 rpm for 30 minutes. It is separated, and the precipitate component and the supernatant component are separated from each other, and the acetone of the supernatant component is volatilized to precipitate and recover the acetone-soluble component, and the value is calculated from the following formula.
Percentage of acetone-soluble matter (%) = (mass of acetone-soluble matter / mass of sample before extraction with acetone) x 100
The "reduced viscosity of the acetone-soluble component" is a value obtained by measuring the reduced viscosity ηsp / C at 25 ° C. for a solution in which 0.2 g of the acetone-soluble component is dissolved in 50 mL of N, N-dimethylformamide.
The "molded article" is a product obtained by molding a thermoplastic resin composition.
"(Meta) acrylic acid" is a general term for acrylic acid and methacrylic acid.
"(Meta) acrylic acid alkyl ester" is a general term for acrylic acid alkyl ester and methacrylic acid alkyl ester.
In the present specification and claims, "~" indicating a numerical range means that the numerical values described before and after the numerical range are included as the lower limit value and the upper limit value.

<Thermoplastic resin composition>
The thermoplastic resin composition of the present invention contains a specific graft copolymer (A) and a specific α-methylstyrene-based copolymer (B).
The thermoplastic resin composition of the present invention may contain another thermoplastic resin (C), if necessary, as long as the effects of the present invention are not impaired.
The thermoplastic resin composition of the present invention may contain other optional components, if necessary, as long as the effects of the present invention are not impaired.

(Graft copolymer (A))
The graft copolymer (A) is obtained by polymerizing a vinyl-based monomer (a2) in the presence of a specific rubber-like polymer (a1).
In the graft copolymer (A), it is difficult to specify how the vinyl-based monomer (a2) is polymerized in the presence of the rubber-like polymer (a1). For example, as the vinyl-based polymer in which the vinyl-based monomer (a2) is polymerized, there are those bonded to the rubber-like polymer (a1) and those not bonded to the rubber-like polymer (a1). .. It is also difficult to specify the molecular weight of the vinyl-based polymer bonded to the rubber-like polymer (a1), the ratio of the constituent units, and the like. That is, there is a situation (impossible / impractical situation) in which the graft copolymer (A) cannot be directly specified by its structure or property, or is almost impractical. Therefore, in the present invention, the graft copolymer (A) can be defined as "a product obtained by polymerizing a vinyl-based monomer (a2) in the presence of a rubber-like polymer (a1)". Appropriate.

Examples of the rubber-like polymer (a1) include conjugated diene-based rubber-like polymers (butadiene-based rubber-like polymers (polybutadiene, styrene-butadiene copolymer, acrylonitrile-butadiene copolymer, acrylic acid ester-butadiene copolymer, etc.). ), Isoprene rubber, chloroprene rubber, styrene / isoprene copolymer, etc.), acrylic rubber-like polymer (butylpolyacrylate, etc.), olefin-based rubber-like polymer (ethylene-propylene copolymer, etc.), silicone-based rubber Examples thereof include state polymers (polyorganosiloxane, etc.), natural rubber, butyl rubber, urethane rubber, chlorinated polyethylene, epichlorohydrin rubber, fluororubber, polysulfide rubber and the like. As the rubber-like polymer (a1), one type may be used alone, or two or more types may be used in combination. The rubber-like polymer (a1) can be obtained by polymerizing a monomer such as butadiene or (meth) acrylic acid ester. The rubber-like polymer (a1) may have a composite rubber structure or a core-shell structure.
The rubber-like polymer (a1) is a conjugated diene-based rubber-like polymer, an acrylic-based rubber-like polymer, an olefin-based rubber-like polymer, or a silicone-based polymer because the molded product has good impact resistance and surface appearance. A rubber-like polymer is preferable, and a conjugated diene-based rubber-like polymer is more preferable.

The average particle size of the rubber-like polymer (a1) is more than 200 nm and 320 nm or less, preferably 205 to 250 nm. When the average particle size of the rubber-like polymer (a1) is within the above range, the balance between the impact resistance of the molded product and the surface appearance is further improved.

Examples of the vinyl-based monomer (a2) include aromatic vinyl-based monomers, (meth) acrylic acid alkyl esters, and vinyl cyanide-based monomers.
Examples of the aromatic vinyl-based monomer include styrene, α-methylstyrene, p-methylstyrene and the like.
Examples of the (meth) acrylic acid alkyl ester include methyl methacrylate, ethyl methacrylate, 2-ethylhexyl methacrylate, methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, t-butyl acrylate and the like. Be done.
Examples of the vinyl cyanide-based monomer include acrylonitrile and methacrylonitrile.
As the vinyl-based monomer (a2), one type may be used alone, or two or more types may be used in combination.
As the vinyl-based monomer (a2), the combined use of styrene and acrylonitrile is preferable from the viewpoint of further improving the impact resistance of the molded product.

The graft copolymer (A) is produced by polymerizing a vinyl-based monomer (a2) in the presence of a rubber-like polymer (a1).
As the polymerization method, an emulsion polymerization method is preferable because the reaction can be controlled so as to proceed stably. Specifically, a method in which a vinyl-based monomer (a2) is collectively charged into a rubber-like polymer (a1) and then polymerized; one of the vinyl-based monomers (a2) in the rubber-like polymer (a1). A method in which the portions are charged first and the rest is dropped onto the polymerization system while being polymerized at any time; a method in which the entire amount of the vinyl-based monomer (a2) is dropped onto the rubber-like polymer (a1) and polymerized at any time can be mentioned. The polymerization of the vinyl-based monomer (a2) may be carried out in one stage or may be carried out in two or more stages. When it is divided into two or more stages, it is also possible to change the type and composition ratio of the vinyl-based monomer (a2) in each stage.

In the emulsion polymerization method, a radical polymerization initiator and an emulsifier are usually used. Further, in order to control the molecular weight and the graft ratio of the graft copolymer (A), a chain transfer agent may be used in combination.

Examples of the radical polymerization initiator include peroxides, azo-based initiators, and redox-based initiators in which an oxidizing agent and a reducing agent are combined. As the radical polymerization initiator, a redox-based initiator is preferable, and a sulfoxylate-based initiator in which ferrous sulfate, disodium ethylenediamine tetraacetate, sodium formaldehyde sulfoxylate, and hydroperoxide are combined is more preferable.

As the emulsifier, various carboxylates such as sodium sarcosate, fatty acid potassium, fatty acid sodium, dipotassium alkenylsuccinate, and loginate soap are preferable because the latex has excellent stability during radical polymerization and the polymerization rate can be increased. Dipotassium alkenyl succinate is more preferable because it can suppress the generation of gas when the graft copolymer (A) and the thermoplastic resin composition containing the graft copolymer (A) are molded at a high temperature.

The mass ratio of the rubber-like polymer (a1) to the vinyl-based monomer (a2) is 10 to 80% by mass for the rubber-like polymer (a1) and 20 to 90% by mass for the vinyl-based monomer (a2). It is more preferable that the rubber-like polymer (a1) is 30 to 70% by mass and the vinyl-based monomer (a2) is 30 to 70% by mass (however, the rubber-like polymer (a1) and the like. The total of the vinyl-based monomers (a2) is 100% by mass.). When the mass ratio of the rubber-like polymer (a1) and the vinyl-based monomer (a2) is within the above range, the impact resistance of the molded product is further excellent.

The graft copolymer (A) is usually obtained in the latex state. As a method for recovering the graft copolymer (A) from the latex of the graft copolymer (A), a slurry is obtained by putting the latex of the graft copolymer (A) into hot water in which a coagulant is dissolved. A wet method of coagulating into a shape; a spray-drying method of semi-directly recovering the graft copolymer (A) by spraying the latex of the graft copolymer (A) in a heated atmosphere can be mentioned.

Examples of the coagulant used in the wet method include inorganic acids (sulfuric acid, hydrochloric acid, phosphoric acid, nitric acid, etc.), metal salts (calcium chloride, calcium acetate, aluminum sulfate, etc.), and are selected according to the emulsifier used in the polymerization. Will be done. For example, when only a carboxylic acid soap such as a fatty acid soap or a rosin acid soap is used as an emulsifier, one or more of the above-mentioned coagulants can be used. When an emulsifier that exhibits stable emulsifying power even in an acidic region such as sodium alkylbenzene sulfonate is used as the emulsifier, a metal salt is suitable as the coagulant.

A slurry-like graft copolymer (A) can be obtained by a wet method. As a method for obtaining the dried graft copolymer (A) from the slurry-like graft copolymer (A), the remaining emulsifier residue is eluted in water and washed, and this slurry is centrifuged and a press dehydrator. A method of dehydrating with an air flow dryer or the like after dehydration with the like; a method of simultaneously performing dehydration and drying with a squeezing dehydrator, an extruder or the like can be mentioned. By these methods, a powder or particulate graft copolymer (A) is obtained.

As the washing conditions, it is preferable to wash under the condition that the amount of the emulsifier residue contained in 100% by mass of the dried graft copolymer (A) is in the range of 0.5 to 2% by mass. When the emulsifier residue in the graft copolymer (A) is 0.5% by mass or more, the fluidity of the graft copolymer (A) and the thermoplastic resin composition containing the same tends to be further improved. When the emulsifier residue in the graft copolymer (A) is 2% by mass or less, the generation of gas when the thermoplastic resin composition is molded at a high temperature can be suppressed.
The graft copolymer (A) discharged from the extrusion dehydrator or extruder may not be recovered and may be directly sent to an extruder or molding machine for producing a thermoplastic resin composition to form a molded product.

The graft copolymer (A) is a vinyl-based weight that is not bonded to the rubber-like polymer (a1) generated when the vinyl-based monomer (a2) is polymerized in the presence of the rubber-like polymer (a1). Including coalescence. The vinyl-based polymer that is not bonded to the rubber-like polymer (a1) is obtained as an acetone-soluble component when the graft copolymer (A) is treated with acetone.

The proportion of the acetone-soluble content of the graft copolymer (A) is 10 to 40% by mass, preferably 15 to 25% by mass. When the proportion of the acetone-soluble content of the graft copolymer (A) is equal to or higher than the lower limit of the above range, the graft copolymers (A) are less likely to aggregate with each other, and a molded product having a highly good surface appearance can be obtained. Be done. When the proportion of the acetone-soluble component of the graft copolymer (A) is not more than the upper limit of the above range, the molded product is excellent in stringiness resistance and impact resistance.

The reduced viscosity of the acetone-soluble component of the graft copolymer (A) is 0.3 to 0.8 dL / g, preferably 0.4 to 0.6 dL / g. When the reduced viscosity of the acetone-soluble component of the graft copolymer (A) is at least the lower limit of the above range, the molded product is excellent in stringiness resistance and impact resistance. When the reduced viscosity of the acetone-soluble component of the graft copolymer (A) is not more than the upper limit of the above range, a molded product having a highly good surface appearance can be obtained.

(Α-Methylstyrene copolymer (B))
The α-methylstyrene-based copolymer (B) has a structural unit derived from α-methylstyrene and a structural unit derived from a vinyl cyanide-based monomer.
The α-methylstyrene-based copolymer (B) has a structural unit derived from other monomers copolymerizable with α-methylstyrene and vinyl cyanide-based monomers, if necessary. May be good.

Examples of the vinyl cyanide-based monomer include acrylonitrile and methacrylonitrile, and acrylonitrile is preferable.
Examples of other monomers include aromatic vinyl-based monomers (excluding α-methylstyrene), unsaturated carboxylic acid-based monomers, unsaturated carboxylic acid anhydride-based monomers, and unsaturated carboxylic acids. Examples thereof include acid ester-based monomers and maleimide-based monomers. Specific examples of other monomers include styrene, p-methylstyrene, (meth) acrylic acid, maleic anhydride, methyl (meth) acrylate, ethyl (meth) acrylate, and n-propyl (meth) acrylic acid. , (Meta) acrylate n-butyl, (meth) acrylate t-butyl, (meth) acrylate n-hexyl, (meth) acrylate chloromethyl, N-methylmaleimide, N-ethylmaleimide, N-cyclohexylmaleimide , N-phenylmaleimide and the like. The other monomers may be used alone or in combination of two or more.

The α-methylstyrene-based copolymer (B) is a structural unit derived from α-methylstyrene and a vinyl cyanide-based single amount from the viewpoint of heat resistance of the obtained molded product and moldability of the thermoplastic resin composition. It is particularly preferable to have a constituent unit derived from the body, a constituent unit derived from an aromatic vinyl-based monomer (excluding α-methylstyrene), and a constituent unit derived from a maleimide-based monomer.

The reduced viscosity of the acetone-soluble component of the α-methylstyrene copolymer (B) is preferably 0.41 to 0.9 dL / g, more preferably 0.45 to 0.6 dL / g. When the reducing viscosity of the acetone-soluble component of the α-methylstyrene copolymer (B) is within the above range, the balance between the stringiness resistance of the molded product and the surface appearance is further improved.

The proportion of each structural unit constituting the α-methylstyrene copolymer (B) is 20 to 90% by mass of the structural unit derived from α-methylstyrene and 10 to 10% by mass of the structural unit derived from the vinyl cyanide monomer. When the ratio of each structural unit, preferably 80% by mass and 0 to 50% by mass of structural units derived from other monomers, is within the above range, the stringing resistance and heat resistance of the molded product are further excellent.

(Other thermoplastic resin (C))
The thermoplastic resin composition of the present invention may contain another thermoplastic resin (C) from the viewpoint of moldability of the thermoplastic resin composition, impact resistance of the molded product, and surface appearance.

Other thermoplastic resins (C) include acrylonitrile-styrene copolymer (AS resin), styrene-maleic anhydride copolymer, acrylonitrile-styrene-N-substituted maleimide ternary copolymer, and styrene-maleic anhydride. -N-substituted maleimide ternary copolymer, acrylonitrile-butadiene-styrene copolymer (ABS resin) (excluding graft copolymer (A)), acrylonitrile-styrene-alkyl (meth) acrylate copolymer (ASA resin) (however, graft copolymer (A) is excluded), acrylonitrile-ethylene-propylene-diene-styrene copolymer (AES resin) (however, graft copolymer (A) is excluded), Polymethyl methacrylate, polycarbonate resin, polybutylene terephthalate (PBT resin), polyethylene terephthalate (PET resin), polyvinyl chloride, polyolefin (polyethylene, polypropylene, etc.), styrene-based elastomer (styrene-butadiene-styrene (SBS), styrene- Butadiene (SBR), hydrogenated SBS, styrene-isoprene-styrene (SIS), etc.), various olefin-based elastomers, various polyester-based elastomers, polystyrene, methyl methacrylate-styrene copolymer (MS resin), acrylonitrile-styrene-methacrylic acid Methyl copolymer, polyacetal resin, modified polyphenylene ether (modified PPE resin), ethylene-vinyl acetate copolymer, polyphenylene sulfide (PPS resin), polyether sulfone (PES resin), polyether ether ketone (PEEK resin), Examples thereof include polymer, liquid crystal polyester resin, and polyamide resin (nylon). As the other thermoplastic resin (C), one type may be used alone, or two or more types may be used in combination.

(Arbitrary ingredient)
The thermoplastic resin composition of the present invention may contain an arbitrary component, if necessary.
Optional components include additives such as various stabilizers (antioxidants, light stabilizers, etc.), lubricants, plasticizers, mold release agents, dyes, pigments, antistatic agents, flame retardants, metal powders, inorganic fillers, etc. Can be mentioned.

(Content of each component)
The content of the graft copolymer (A) is such that the content of the rubber-like polymer (a1) in the thermoplastic resin composition (100% by mass) is 10 to 20% by mass. The content of the rubber-like polymer (a1) is preferably 13 to 18% by mass based on the thermoplastic resin composition (100% by mass). When the content of the rubber-like polymer (a1) is at least the lower limit of the above range, the impact resistance of the molded product is excellent. When the content of the rubber-like polymer (a1) is not more than the upper limit of the above range, the stringiness resistance of the molded product is excellent.

The content of the α-methylstyrene copolymer (B) is 31 to 80% by mass, preferably 40 to 70% by mass, based on the thermoplastic resin composition (100% by mass). When the content of the α-methylstyrene copolymer (B) is at least the lower limit of the above range, the molded product is excellent in stringiness resistance and heat resistance. When the content of the α-methylstyrene copolymer (B) is not more than the upper limit of the above range, the impact resistance of the molded product is excellent and the moldability of the thermoplastic resin composition is excellent.

When the other thermoplastic resin (C) is contained, the content of the other thermoplastic resin (C) is preferably 5 to 50% by mass, preferably 5 to 25% by mass, based on the thermoplastic resin composition (100% by mass). % Is more preferable.

(Manufacturing method of thermoplastic resin composition)
The thermoplastic resin composition of the present invention contains a graft copolymer (A), an α-methylstyrene-based copolymer (B), and if necessary, another thermoplastic resin (C) and optional components. It is produced by mixing and dispersing with a V-type blender, a Henschel mixer or the like, and melt-kneading the mixture with a melt-kneader such as a screw extruder, a Banbury mixer, a pressure kneader or a mixing roll. Further, if necessary, the melt-kneaded product may be pelletized using a pelletizer or the like.

(Action effect)
The thermoplastic resin composition of the present invention described above contains the graft copolymer (A) and the α-methylstyrene-based copolymer (B), and the content of the rubber-like polymer (a1) is thermoplastic. Since it is 10 to 20% by mass of the resin composition and the content of the α-methylstyrene-based copolymer (B) is 31 to 70% by mass of the thermoplastic resin composition, it is used during hot plate welding. It is possible to obtain a molded product having excellent stringiness resistance, a highly good surface appearance, and sufficient impact resistance and heat resistance as a material for a lamp housing. According to such a thermoplastic resin composition of the present invention, it is possible to obtain molded products suitable as vehicle parts such as lamps, interiors and exteriors, OA equipment, home appliance parts, medical appliances, and various industrial materials. ..

<Molded product>
The molded article of the present invention comprises the thermoplastic resin composition of the present invention.
The molded article of the present invention can be produced by molding the thermoplastic resin composition of the present invention by a known molding method.
Examples of the molding method include an injection molding method, a press molding method, an extrusion molding method, a vacuum forming method, a blow molding method and the like.

The molded product of the present invention has excellent stringing resistance during hot plate welding, has a highly good surface appearance, and has sufficient impact resistance and heat resistance as a material for a lamp housing. Examples of applications of such molded products include vehicle parts such as lamps, interiors, and exteriors, OA equipment, home appliance parts, medical appliances, various industrial materials, and the like, and vehicle lamps are suitable.

The molded product of the present invention can be welded to another molded product by hot plate welding to form a bonded product. Examples of the material to be another molded product to be joined include acrylic resin and polycarbonate resin. The bonded product obtained from the molded product of the present invention is excellent in appearance because the stringing phenomenon when the joint portion is welded to the hot plate is suppressed.

Hereinafter, the present invention will be described in more detail with reference to Examples. The present invention is not limited to these examples.
Hereinafter, "parts" and "%" mean "parts by mass" and "% by mass", respectively.

<Measurement, evaluation>
(Average particle size)
Using a dynamic light scattering type particle size distribution measuring device (Nanotrac UPA-EX150, manufactured by Nikkiso Co., Ltd.), the particle size distribution based on the volume of the polymer in latex is measured by the dynamic light scattering method, and the volume is measured from the particle size distribution. The average particle size was calculated.

(Ratio of acetone-soluble components)
2.5 g of the polymer was added to 80 mL of acetone, and the mixture was heated under reflux at 65 to 70 ° C. for 3 hours. The obtained suspended acetone solution was centrifuged at 14000 rpm for 30 minutes, and the precipitate component and the supernatant component were separated from each other. Acetone, which is a supernatant component, was volatilized to precipitate and recover the acetone-soluble component of the graft copolymer, and the proportion of the acetone-soluble component was calculated from the following formula.
Percentage of acetone-soluble matter (%) = (mass of acetone-soluble matter / mass of polymer before extraction with acetone) x 100

(Reduced viscosity of acetone-soluble components)
A solution in which 0.2 g of an acetone-soluble component was dissolved in 50 mL of N, N-dimethylformamide was reduced in viscosity at 25 ° C. using an automatic viscosity measuring device (SS-500-L2, manufactured by Shibayama Kagaku Kikai Seisakusho Co., Ltd.). ηsp / C was measured.

(Impact resistance)
A test piece (molded product) was prepared from a pellet-shaped thermoplastic resin composition using an injection molding machine (manufactured by Toshiba Machine Co., Ltd., IS55FP-1.5A) in accordance with ISO 3167. The Charpy impact strength of the test piece was measured in an atmosphere of 23 ° C. in accordance with ISO 179.

(Surface appearance)
Using a 4 ounce injection molding machine (manufactured by Japan Steel Works, Ltd.), the length is from a pelletized thermoplastic resin composition under the conditions of a cylinder set temperature of 260 ° C, a mold temperature of 60 ° C, and an injection rate of 20 g / sec. A plate-shaped molded product having a width of 100 mm, a width of 100 mm, and a thickness of 2 mm was produced.
An aluminum vapor deposition film with a thickness of 50 nm was used on the surface of the molded product using a vacuum vapor deposition machine (VPC-1100 manufactured by ULVAC Kiko Co., Ltd.) under ^{the conditions of a vacuum degree of 6.0 × 10 -3} Pa and a film formation rate of 1 nm / sec. Was formed.
The diffuse reflectance of the directly vapor-deposited molded product was measured using a reflectance meter (TR-1100AD, manufactured by Tokyo Denshoku Co., Ltd.) to evaluate the brilliance. The smaller the diffuse reflectance, the better the brilliance, that is, the surface appearance.

(Heat-resistant)
A test piece (molded product) was prepared from a pellet-shaped thermoplastic resin composition using an injection molding machine (manufactured by Toshiba Machine Co., Ltd., IS55FP-1.5A) in accordance with ISO 3167. The deflection temperature under load (HDT) of the test piece is measured in accordance with ISO 75 using an HDT testing machine (manufactured by Toyo Seiki Seisakusho Co., Ltd., 6A-2) under the conditions of a load of 1.80 MPa and a flat width (4 mm thickness). bottom. The higher the HDT value, the better the heat resistance.

(Thread resistance)
Using a 4 ounce injection molding machine (manufactured by Japan Steel Works, Ltd.), the length is 100 mm from the pelletized thermoplastic resin composition under the conditions of a cylinder set temperature of 260 ° C., a mold temperature of 60 ° C., and an injection rate of 60 g / sec. A plate-shaped test piece (molded product) having a width of 20 mm and a thickness of 3 mm was produced.
The test piece was brought into contact with a hot plate heated to 240 ° C. for 12 seconds and then pulled apart horizontally, and the stringing level (length and number) at that time was visually confirmed. The evaluation was carried out according to the following criteria.
◎ ・ ・ ・ The average stringing length is less than 1 mm, and the number of threads is 5 or less.
○ ・ ・ ・ The average stringing length is 1 to 4 mm, and the number of threads is 5 or less.
Δ: The average stringing length is 4 to 8 mm, and the number of threads is 5 or less.
×: The average stringing length is 10 mm or more.
(If the number is 6 or more in each standard, the evaluation is lowered by 1 rank)

<Manufacturing of rubber-like polymer (a1)>
(Manufacturing Example 1)
Production of polybutadiene (a1-1):
150 parts of deionized water, 100 parts of 1,3-butadiene, 3.0 parts of hardened potassium potassium soap, 0.3 part of sodium organic sulfonate, 0 of t-dodecyl mercaptan in a pressure-resistant container equipped with a stirrer. .2 parts, 0.3 parts of potassium persulfate having a 10-hour half-life temperature of 71 ° C., and 0.14 parts of potassium hydroxide were charged. Polymerization was started by raising the temperature to 60 ° C. with stirring under a nitrogen atmosphere. When the polymerization rate was 65%, 5 parts of deionized water in which 0.1 part of potassium persulfate was dissolved was added to a pressure resistant container to raise the polymerization temperature to 70 ° C. The polymerization was completed with a reaction time of 13 hours and a polymerization conversion rate of 90%. 0.1 part of sodium formaldehyde sulfoxylate was added to a pressure resistant container to obtain a polybutadiene latex. The polybutadiene latex had an average particle size of 80 nm and a solid content of 52.0%. This is a latex of polybutadiene (a1-1).

(Manufacturing Example 2)
Production of polybutadiene (a1-2):
1.25 parts of acetic acid was added to 100 parts of the solid content of the latex of the polybutadiene (a1-1) obtained in Production Example 1 to enlarge it (enlargement step), and a polybutadiene latex having an average particle diameter of 210 nm was obtained. rice field. This is a latex of polybutadiene (a1-2).

(Manufacturing Example 3)
Production of polybutadiene (a1-3):
1.9 parts of acetic acid was added to 100 parts of the solid content of the latex of the polybutadiene (a1-1) obtained in Production Example 1 to enlarge it (enlargement step), and a polybutadiene latex having an average particle diameter of 310 nm was obtained. rice field. This is a latex of polybutadiene (a1-3).

<Manufacturing of graft copolymer (A1)>
(Manufacturing Example 4)
Production of Graft Copolymer (A-1):
40 parts of the latex of polybutadiene (a1-2) obtained in Production Example 2 in terms of solid content and 170 parts of deionized water in a reactor equipped with a reagent injection container, a cooling tube, a jacket heater and a stirrer. , 0.3 part of disproportionated potassium rosinate, 0.01 part of ferrous sulfate heptahydrate, 0.2 part of sodium pyrophosphate and 0.5 part of crystalline glucose were charged. The contents were heated to 60 ° C. with stirring, and a mixture consisting of 16 parts of acrylonitrile, 44 parts of styrene, 0.4 part of cumene hydroperoxide and 0.2 part of t-dodecyl mercaptan was added over 100 minutes. Graft polymerization was carried out by dropping the mixture. After completion of the dropping, the temperature was raised to 75 ° C., and the mixture was further stirred and held for 1 hour to complete the graft polymerization reaction. An antioxidant was added to the polymer obtained by such a reaction to obtain a latex of the graft copolymer (A-1).
The latex of the graft copolymer (A-1) is put into a dilute sulfuric acid aqueous solution having a liquid temperature of 80 ° C., then heated to 90 ° C. over 30 minutes to coagulate, and then dehydrated, washed and dried to form a powder. The graft copolymer (A-1) of the above was obtained. Table 1 shows the proportion of the acetone-soluble component, the reduced viscosity, and the average particle size of the rubbery polymer.

(Manufacturing Example 5)
Production of Graft Copolymer (A-2):
In a reactor equipped with a reagent injection container, a cooling tube, a jacket heater and a stirrer, 50 parts of the polybutadiene (a1-3) latex obtained in Production Example 3 in terms of solid content and 170 parts of deionized water , 0.3 part of disproportionated potassium rosinate, 0.01 part of ferrous sulfate heptahydrate, 0.1 part of sodium pyrophosphate and 0.2 part of crystalline glucose were charged. The contents were heated to 60 ° C. with stirring, and a mixture consisting of 12 parts of acrylonitrile, 38 parts of styrene, 0.4 part of cumene hydroperoxide and 0.1 part of t-dodecyl mercaptan was added over 100 minutes. Graft polymerization was carried out by dropping the mixture. After completion of the dropping, the temperature was raised to 75 ° C., and the mixture was further stirred and held for 1 hour to complete the graft polymerization reaction. An antioxidant was added to the polymer obtained by such a reaction to obtain a latex of the graft copolymer (A-2).
The latex of the graft copolymer (A-2) is put into a dilute sulfuric acid aqueous solution having a liquid temperature of 80 ° C., then heated to 90 ° C. over 30 minutes to coagulate, and then dehydrated, washed and dried to form a powder. The graft copolymer (A-2) of the above was obtained. Table 1 shows the proportion of the acetone-soluble component, the reduced viscosity, and the average particle size of the rubbery polymer.

(Manufacturing Example 6)
Production of Graft Copolymer (A-3):
65 parts of the latex of polybutadiene (a1-3) obtained in Production Example 3 in terms of solid content and 170 parts of deionized water in a reactor equipped with a reagent injection container, a cooling tube, a jacket heater and a stirrer. , 0.6 part of disproportionated potassium rosinate, 0.01 part of ferrous sulfate heptahydrate, 0.1 part of sodium pyrophosphate and 0.2 part of crystalline glucose were charged. The contents were heated to 60 ° C. with stirring, and a mixture consisting of 10 parts of acrylonitrile, 25 parts of styrene, 0.1 part of cumene hydroperoxide and 0.02 part of t-dodecyl mercaptan was added over 100 minutes. Graft polymerization was carried out by dropping the mixture. After completion of the dropping, the temperature was raised to 75 ° C., and the mixture was further stirred and held for 1 hour to complete the graft polymerization reaction. An antioxidant was added to the polymer obtained by such a reaction to obtain a latex of the graft copolymer (A-3).
The latex of the graft copolymer (A-3) is put into a dilute sulfuric acid aqueous solution having a liquid temperature of 80 ° C., and then the temperature is raised to 90 ° C. over 30 minutes to solidify, and then dehydrated, washed and dried to form a powder. The graft copolymer (A-3) of the above was obtained. Table 1 shows the proportion of the acetone-soluble component, the reduced viscosity, and the average particle size of the rubbery polymer.

(Manufacturing Example 7)
Production of Graft Copolymer (A-4):
In a reactor equipped with a reagent injection container, a cooling tube, a jacket heater and a stirrer, 45 parts of the polybutadiene (a1-1) latex obtained in Production Example 1 in terms of solid content and 170 parts of deionized water , 1.7 parts of disproportionated potassium rosinate, 0.01 part of ferrous sulfate heptahydrate, 0.1 part of sodium pyrophosphate and 0.2 part of crystalline glucose were charged. The contents were heated to 60 ° C. with stirring, and a mixture consisting of 15 parts of acrylonitrile, 40 parts of styrene, 0.4 part of cumene hydroperoxide and 0.02 part of t-dodecyl mercaptan was added over 100 minutes. Graft polymerization was carried out by dropping the mixture. After completion of the dropping, the temperature was raised to 75 ° C., and the mixture was further stirred and held for 1 hour to complete the graft polymerization reaction. An antioxidant was added to the polymer obtained by such a reaction to obtain a latex of a graft copolymer (A-4).
The latex of the graft copolymer (A-4) is put into a dilute sulfuric acid aqueous solution having a liquid temperature of 80 ° C., then heated to 90 ° C. over 30 minutes to coagulate, and then dehydrated, washed and dried to form a powder. The graft copolymer (A-4) of the above was obtained. Table 1 shows the proportion of the acetone-soluble component, the reduced viscosity, and the average particle size of the rubbery polymer.

(Manufacturing Example 8)
Production of Graft Copolymer (A-5):
40 parts of the latex of polybutadiene (a1-2) obtained in Production Example 2 in terms of solid content and 170 parts of deionized water in a reactor equipped with a reagent injection container, a cooling tube, a jacket heater and a stirrer. , 0.3 part of disproportionated potassium rosinate, 0.01 part of ferrous sulfate heptahydrate, 0.2 part of sodium pyrophosphate and 0.5 part of crystalline glucose were charged. The contents were heated to 60 ° C. with stirring, and a mixture consisting of 16 parts of acrylonitrile, 44 parts of styrene, 0.6 parts of cumene hydroperoxide and 0.6 parts of t-dodecyl mercaptan was added over 100 minutes. Graft polymerization was carried out by dropping the mixture. After completion of the dropping, the temperature was raised to 75 ° C., and the mixture was further stirred and held for 1 hour to complete the graft polymerization reaction. An antioxidant was added to the polymer obtained by such a reaction to obtain a latex of a graft copolymer (A-5).
The latex of the graft copolymer (A-5) is put into a dilute sulfuric acid aqueous solution having a liquid temperature of 80 ° C., then heated to 90 ° C. over 30 minutes to coagulate, and then dehydrated, washed and dried to form a powder. The graft copolymer (A-5) of the above was obtained. Table 1 shows the proportion of the acetone-soluble component, the reduced viscosity, and the average particle size of the rubbery polymer.

(Manufacturing Example 9)
Production of Graft Copolymer (A-6):
200 parts of ion-exchanged water, 2 parts of potassium oleate, 4 parts of sodium dioctyl sulfosuccinate, ferrous sulfate heptahydrate in a reactor equipped with a reagent injection container, a cooling tube, a jacket heater and a stirrer. 0.003 part of, 0.009 part of ethylenediamine tetraacetic acid disodium salt, and 0.3 part of sodium formaldehyde sulfoxylate were charged under a nitrogen stream and the temperature was raised to 60 ° C. From the time when the temperature reached 60 ° C., a mixture consisting of 85 parts of n-butyl acrylate, 15 parts of methacrylic acid and 0.5 part of cumene hydroperoxide was continuously added dropwise over 120 minutes. After completion of the dropping, aging was carried out for another 2 hours at 60 ° C., and the solid content was 33%, the polymerization conversion rate was 96%, and the volume average particle size of the acid group-containing copolymer was 120 nm. A copolymer latex (K) was obtained.

190 parts of ion-exchanged water, 0.6 parts of dipotassium alkenyl succinate, 50 parts of n-butyl acrylate, allyl methacrylate in a reactor equipped with a reagent injection container, a condenser, a jacket heater and a stirrer. A mixture consisting of 0.6 parts of t-butyl hydroperoxide and 0.1 parts of t-butyl hydroperoxide was added. The atmosphere was replaced with nitrogen by passing a nitrogen stream through this reactor, and the internal temperature was raised to 55 ° C. When the internal temperature reaches 55 ° C, 0.0001 parts of ferrous sulfate heptahydrate, 0.0003 parts of ethylenediamine tetraacetate disodium salt, 0.2 parts of sodium formaldehyde sulfoxylate, ion-exchanged water An aqueous solution consisting of 10 parts of the above was added to initiate radical polymerization. After the heat generation of polymerization was confirmed, the jacket temperature was set to 75 ° C., and the polymerization was continued until the heat generation of polymerization was no longer confirmed, and this state was maintained for another 1 hour. The volume average particle size of the obtained rubber-like polymer was 100 nm. After the liquid temperature inside the reactor was lowered to 70 ° C., 0.6 part of a 5% aqueous sodium pyrophosphate solution was added as a solid content. After controlling the internal temperature at 70 ° C., 1.2 parts of the acid group-containing copolymer latex (K) was added as a solid content, and the mixture was stirred for 30 minutes and enlarged to obtain a latex of a rubber-like polymer. The volume average particle size of the obtained latex-like rubber-like polymer was 285 nm.

To the obtained rubbery polymer latex, 0.001 part of ferrous sulfate heptahydrate, 0.003 part of ethylenediamine tetraacetate disodium salt, 0.3 part of sodium formaldehyde sulfoxylate, ion-exchanged water. An aqueous solution consisting of 10 parts of the above was added. Then, a mixed solution consisting of 15 parts of acrylonitrile, 35 parts of styrene, and 0.225 parts of t-butyl hydroperoxide was added dropwise over 100 minutes for polymerization. After completion of the dropping, the temperature of 80 ° C. was maintained for 30 minutes, 0.05 part of cumene hydroperoxide was added, the temperature of 75 ° C. was maintained for 30 minutes, and then the mixture was cooled to obtain a graft copolymer (graft copolymer). The latex of A-6) was obtained.
The latex of the graft copolymer (A-6) is put into a dilute sulfuric acid aqueous solution having a liquid temperature of 80 ° C., then the temperature is raised to 90 ° C. over 30 minutes to solidify, and then dehydrated, washed and dried to form a powder. The graft copolymer (A-6) of the above was obtained. Table 1 shows the proportion of the acetone-soluble component, the reduced viscosity, and the average particle size of the rubbery polymer.

<Manufacturing of α-methylstyrene copolymer (B)>
(Manufacturing Example 9)
Production of α-methylstyrene copolymer (B-1):
29 parts of acrylonitrile, 24 parts of styrene, 36 parts of α-methylstyrene and 11 parts of N-phenylmaleimide were polymerized by known suspension polymerization, and acrylonitrile-styrene-α-methylstyrene-N-phenylmaleimide quaternary element. A copolymer was obtained. This is referred to as an α-methylstyrene copolymer (B-1). The reduced viscosity of the acetone-soluble component was 0.47 dL / g.

(Manufacturing Example 10)
Production of α-methylstyrene copolymer (B-2):
27 parts of acrylonitrile and 73 parts of α-methylstyrene were polymerized by known suspension polymerization to obtain an acrylonitrile-α-methylstyrene copolymer. This is referred to as an α-methylstyrene copolymer (B-2). The reduced viscosity of the acetone-soluble component was 0.51 dL / g.

(Manufacturing Example 11)
Production of α-methylstyrene copolymer (B-3):
27 parts of acrylonitrile and 73 parts of α-methylstyrene were polymerized by known suspension polymerization to obtain an acrylonitrile-α-methylstyrene copolymer. This is referred to as an α-methylstyrene copolymer (B-3). The reduced viscosity of the acetone-soluble component was 0.37 dL / g.

(Manufacturing Example 12)
Production of α-methylstyrene copolymer (B-4):
27 parts of acrylonitrile and 73 parts of α-methylstyrene were polymerized by known suspension polymerization to obtain an acrylonitrile-α-methylstyrene copolymer. This is referred to as an α-methylstyrene copolymer (B-4). The reduced viscosity of the acetone-soluble component was 0.91 dL / g.

<Manufacturing of other thermoplastic resin (C)>
(Manufacturing Example 13)
Manufacture of other thermoplastic resins (C-1):
27 parts of acrylonitrile and 73 parts of styrene were polymerized by a known suspension polymerization to obtain an acrylonitrile-styrene copolymer. This is referred to as another thermoplastic resin (C-1). The reduced viscosity of the acetone-soluble component was 0.88 dL / g.

(Manufacturing Example 14)
Manufacture of other thermoplastic resins (C-2):
15 parts of acrylonitrile, 55 parts of styrene and 30 parts of N-phenylmaleimide were polymerized by a known continuous solution polymerization to obtain an acrylonitrile-styrene-N-phenylmaleimide ternary copolymer. This is referred to as another thermoplastic resin (C-2). The reduced viscosity of the acetone-soluble component was 0.60 dL / g.

<Manufacturing of thermoplastic resin compositions and molded products>
(Examples 1 to 7, Comparative Examples 1 to 8)
The amounts of the graft copolymer (A), α-methylstyrene copolymer (B) and other thermoplastic resin (C) shown in Tables 2 to 5, and 0.5 part of ethylene bisstearylamide and silicone. 0.1 part of oil SH200 (manufactured by Toray Dow Corning Co., Ltd.) was mixed using a Henschel mixer. A thermoplastic resin composition obtained by melt-kneading the obtained mixture at 250 ° C. using a screw extruder (manufactured by Japan Steel Works, Ltd., TEX-30α twin-screw extruder) and then pelletizing it with a pelletizer. Got

A test piece (molded article) was prepared using the obtained pellet-shaped thermoplastic resin composition. The obtained molded product was evaluated for impact resistance, surface appearance, heat resistance, and stringing resistance. The results are shown in Tables 2 to 5.

From the thermoplastic resin compositions of Examples 1 to 7, it is excellent in stringiness resistance at the time of hot plate welding, has a highly good surface appearance, and has sufficient impact resistance and heat resistance as a material for a lamp housing. A molded product having the above was obtained.
On the other hand, the molded products obtained from the thermoplastic resin compositions of Comparative Examples 1 to 8 were inferior in any of the items of stringiness resistance, surface appearance, impact resistance, and heat resistance at the time of hot plate welding. rice field.
The molded product of Comparative Example 1 had an inferior surface appearance because the acetone-soluble content of the graft copolymer (A) was less than 10% by mass.
In the molded product of Comparative Example 2, the average particle size of the rubber-like polymer was 200 nm or less, and the acetone-soluble content of the graft copolymer (A) exceeded 40% by mass. The sex was inferior.
The molded product of Comparative Example 3 was inferior in stringiness resistance because the reduced viscosity of the acetone-soluble component of the graft copolymer (A) was less than 0.3 dL / g.
The molded product of Comparative Example 4 was inferior in stringiness resistance because it did not contain the α-methylstyrene copolymer (B).
The molded product of Comparative Example 5 was inferior in impact resistance because the content of the rubber-like polymer was less than 10% by mass.
The molded product of Comparative Example 6 was inferior in stringiness resistance because the content of the rubber-like polymer exceeded 20% by mass.
The molded product of Comparative Example 7 was inferior in stringiness resistance and heat resistance because the content of the α-methylstyrene copolymer (B) was less than 31% by mass.
The molded product of Comparative Example 8 was inferior in impact resistance because the content of the α-methylstyrene copolymer (B) exceeded 80% by mass.

According to the present invention, it is possible to obtain a molded product having excellent stringing resistance at the time of hot plate welding, having a highly good surface appearance, and having sufficient impact resistance and heat resistance as a material for a lamp housing. It is possible to provide a thermoplastic resin composition that can be used. In particular, the balance between stringiness, surface appearance, and impact resistance of molded products is at a very high level that cannot be obtained with conventionally known thermoplastic resin compositions, and is used for vehicles such as lamps, interiors, and exteriors. Its utility value as parts, OA equipment, home appliance parts, medical instruments, and various industrial materials is extremely high.

Claims (7)

It is obtained by polymerizing a vinyl-based monomer (a2) in the presence of a rubber-like polymer (a1) having an average particle size of more than 200 nm and 320 nm or less, and has an acetone-soluble content of 10 to 40. The graft copolymer (A), which is by mass% and has a reduced viscosity of the acetone-soluble component of 0.3 to 0.8 dL / g, and
α-Methylstyrene copolymer (B) having a structural unit derived from α-methylstyrene and a structural unit derived from a vinyl cyanide monomer (however, it is derived from a (meth) acrylic acid ester-based monomer. It is a thermoplastic resin composition containing ( does not contain a constituent unit) and
The content of the rubber-like polymer (a1) is 10 to 20% by mass of the thermoplastic resin composition (100% by mass).
A thermoplastic resin composition in which the content of the α-methylstyrene copolymer (B) is 31 to 80% by mass based on the thermoplastic resin composition (100% by mass). The α-methylstyrene copolymer (B) is a structural unit derived from α-methylstyrene, a structural unit derived from a vinyl cyanide monomer, and an aromatic vinyl monomer (however, α-methyl). The thermoplastic resin composition according to claim 1, which has a structural unit derived from (excluding styrene) and a structural unit derived from a maleimide-based monomer. The thermoplastic resin composition according to claim 1 or 2, wherein the rubber-like polymer (a1) has an average particle size of 205 to 250 nm. The thermoplastic resin according to any one of claims 1 to 3, wherein the reduced viscosity of the acetone-soluble component of the α-methylstyrene copolymer (B) is 0.41 to 0.9 dL / g. Composition. The thermoplastic according to any one of claims 1 to 4, wherein the content of the rubber-like polymer (a1) is 13 to 18% by mass in the thermoplastic resin composition (100% by mass). Resin composition. A molded product comprising the thermoplastic resin composition according to any one of claims 1 to 5. The molded product according to claim 6, which is used for joining with another molded product by hot plate welding.