Graft copolymer, thermoplastic resin composition and molded article

Abstract

To provide a graft copolymer and a thermoplastic resin composition capable of obtaining a molded article excellent in fingerprint resistance and appearance even without coating and to provide a molded article excellent in fingerprint resistance and appearance even without coating.SOLUTION: There is provided a graft copolymer obtained by graft-polymerizing at least one vinyl monomer (Y) selected from the group consisting of a (meth)acrylate (b) having one or more of a linear or branched hydrocarbon group having 1 to 10 carbon atoms, an alicyclic group and an aromatic group or the like in the presence of a copolymer (A) containing a structural unit based on a (meth)acrylate (a) having a linear or branched hydrocarbon group having 11 or more carbon atoms in a specific ratio, wherein when performing differential scanning calorimetry measurements under a specific condition, one or more glass transition temperatures are observed in a region of -100°C or more and less than 90°C and in a region of 90°C or more, respectively.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a graft copolymer, a thermoplastic resin composition, and a molded article. [Background technology]

[0002] Jet-black or metallic glossy exterior materials are widely used as interior and exterior components of automobiles, housings of electronic devices, etc. Jet-black or metallic glossy exterior materials have a problem in that fingerprint stains are easily noticeable, and there is an increasing need for fingerprint resistance in order to maintain a sense of luxury and cleanliness. One method for imparting fingerprint resistance to the surface of a molded product is to apply a stain-resistant agent to the surface of the molded product to form a water-repellent and lipophilic coating that improves compatibility with sebum components and makes fingerprints less noticeable even if they are left on the product. Patent Document 1 discloses a stain resistance imparting agent containing a (meth)acrylic copolymer containing, as a copolymerization component, a (meth)acrylate having a water repellent group such as a long-chain alkyl group. In Patent Document 1, the (meth)acrylic copolymer is produced by solution polymerization, and the obtained solution is directly blended into the stain resistance imparting agent.

[0003] On the other hand, (meth)acrylates having long-chain alkyl groups have a problem in that they are difficult to polymerize in emulsion because they have a much lower solubility in water compared to styrene, etc. Therefore, methods of polymerizing (meth)acrylates having long-chain alkyl groups in an aqueous system are being investigated. Patent Document 2 discloses a method for obtaining an aqueous latex of a (meth)acrylic copolymer by emulsifying and dispersing a monomer mixture containing a specific ratio of a mixture of a (meth)acrylate having a long-chain alkyl group and a hydrophilic monomer in a specific mass ratio in an aqueous emulsifier solution to form monomer droplets of 5 μm or less, and polymerizing the monomer droplets in the presence of a polymerization initiator. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2004-359834 A [Patent Document 2] Japanese Patent Application Publication No. 6-192341 Summary of the Invention [Problem to be solved by the invention]

[0005] For example, in the case of car navigation systems, the spread of touch panels has increased the opportunities for people to touch the screen with their hands, and as a result, the possibility of touching the case with their hands is also increasing. Even if the case has a jet black or metallic luster appearance to meet the needs of the user, there is a concern that touching the case with one's hands will ruin the appearance, and so there is a demand for further improvements in fingerprint resistance. On the other hand, from the viewpoint of reducing the number of processes and taking measures against VOCs, there is an increasing demand for unpainted products with high appearance, and it is desirable to be able to achieve fingerprint resistance without painting.

[0006] Therefore, the present inventors have investigated kneading the (meth)acrylic copolymer described in Patent Document 1 with a thermoplastic resin and molding the mixture. However, since this (meth)acrylic copolymer contains a (meth)acrylate having a long-chain alkyl group as a copolymerization component, it has a low glass transition temperature and is easily fused, making it difficult to mix and knead with a thermoplastic resin, or even if mixing and kneading are possible, there is a problem that defects such as bumps and delamination occur in the molded product, resulting in a poor appearance. The (meth)acrylic copolymer described in Patent Document 2 has the same problem as above. In addition, in the method of Patent Document 2, when polymerization is performed, the (meth)acrylate having a long-chain alkyl group does not migrate to a micelle, and homopolymers of the (meth)acrylate having a long-chain alkyl group and other monomers are generated. When this is kneaded with a thermoplastic resin, the homopolymer of the (meth)acrylate having a long-chain alkyl group is not compatible with the thermoplastic resin, and the appearance of the molded product becomes worse.

[0007] One aspect of the present invention aims to provide a graft copolymer and a thermoplastic resin composition which can give a molded article having excellent fingerprint resistance and appearance even without painting, and a molded article having excellent fingerprint resistance and appearance even without painting. [Means for solving the problem]

[0008] The present invention has the following aspects. [1] A graft copolymer in which a vinyl monomer (Y) is graft polymerized in the presence of a copolymer (A), the copolymer (A) contains a structural unit based on a (meth)acrylate (a) having a linear or branched hydrocarbon group having 11 or more carbon atoms, and a structural unit based on a vinyl monomer (X) other than the (meth)acrylate (a); the ratio of the structural units based on the (meth)acrylate (a) to the total of 100 parts by mass of all structural units constituting the copolymer (A) is 10 to 70 parts by mass; the vinyl monomer (Y) comprises at least one selected from the group consisting of (b) a (meth)acrylate having at least one of a linear or branched hydrocarbon group having 1 to 10 carbon atoms, an alicyclic group, and an aromatic group, (c) an aromatic vinyl, (d) a vinyl cyanide, (e) a maleic anhydride, and (f) a maleimide compound, A graft copolymer, which, when subjected to differential scanning calorimetry under conditions of heating from 35°C to 200°C at a heating rate of 10°C / min in a nitrogen atmosphere, cooling to -100°C, and heating again to 200°C, has one or more glass transition temperatures observed in both the region from -100°C to less than 90°C and the region from 90°C onwards. [2] The copolymer (A) is a graft copolymer according to [1], having a polymerizable unsaturated bond at the end of the main chain. [3] The graft copolymer according to [1] or [2], wherein the ratio of the copolymer (A) to the total of 100 parts by mass of the copolymer (A) and the vinyl monomer (Y) is 10 to 80 parts by mass. [4] The graft copolymer according to any one of [1] to [3] above, having a toluene-insoluble content of 50% by mass or less. [5] The graft copolymer according to any one of [1] to [4], wherein the copolymer (A) contains a structural unit based on a crosslinking agent in a ratio of 0 to 1.0 part by mass per 100 parts by mass of the total of all structural units constituting the copolymer (A). [6] The graft copolymer according to any one of [1] to [5] above, having a weight average molecular weight of 1,000 to 1,000,000. [7] A thermoplastic resin composition comprising the graft copolymer according to any one of [1] to [6] above and another thermoplastic resin. [8] A molded article comprising the thermoplastic resin composition according to [7]. Effect of the Invention

[0009] According to the present invention, it is possible to provide a graft copolymer and a thermoplastic resin composition which can give a molded article having excellent fingerprint resistance and appearance even without painting, and a molded article having excellent fingerprint resistance and appearance even without painting. [Brief description of the drawings]

[0010] [Figure 1] FIG. 13 is a diagram for explaining a method for wiping off fingerprints in the evaluation of appearance (fingerprint resistance). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] In this specification, (meth)acrylate is a general term for acrylate and methacrylate. A vinyl monomer is a compound that has one polymerizable unsaturated double bond. The crosslinking agent is a compound having two or more polymerizable unsaturated bonds. The toluene insoluble matter is measured by the method described in the Examples below. The weight average molecular weight is a value calculated using standard polystyrene as measured by gel permeation chromatography (GPC). Details are as described in the Examples below. Hereinafter, the weight average molecular weight may be referred to as Mw. The volume average particle size of dispersed particles in an aqueous dispersion of a latex or the like is measured by a dynamic light scattering method. The glass transition temperature is a value determined by differential scanning calorimetry (DSC), specifically, the glass transition temperature observed when DSC is performed under the conditions of heating from 35° C. to 200° C. at 10° C. / min in a nitrogen atmosphere, cooling to -100° C., and heating again to 200° C. Hereinafter, the glass transition temperature may be referred to as Tg. "Excellent fingerprint resistance" means that fingerprints are not easily noticeable when left on the surface and / or that fingerprints can be easily wiped off. The symbol "~" indicating a range of values ​​means that the values ​​before and after it are included as the lower and upper limits.

[0012] [Graft Copolymer] The graft copolymer according to one embodiment of the present invention (hereinafter also referred to as "graft copolymer (B)") is a copolymer obtained by graft polymerization of a vinyl monomer (Y) in the presence of the copolymer (A). The graft copolymer (B) contains a copolymer (A) portion and a polymer portion in which a vinyl monomer (Y) is polymerized. It is not easy to specify the structure of the graft copolymer in detail. Therefore, there are circumstances (impossible or impractical circumstances) in which it is impossible or practical to directly specify the graft copolymer (B) based on its structure or properties. The copolymer (A) and the vinyl monomer (Y) will be described in detail later.

[0013] The proportion of copolymer (A) relative to 100 parts by mass of the total of copolymer (A) and vinyl monomer (Y) is preferably 10 to 80 parts by mass, more preferably 20 to 70 parts by mass. When the proportion of copolymer (A) is equal to or more than the above lower limit, the effect of imparting fingerprint resistance is more excellent, and when the proportion is equal to or more than the above lower limit, the handleability of graft copolymer (B) is more excellent.

[0014] The toluene insoluble content of the graft copolymer (B) is preferably 50% by mass or less, more preferably 25% by mass or less, and particularly preferably 0% by mass, based on 100% by mass of the graft copolymer (B). If the toluene insoluble content of the graft copolymer (B) is equal to or less than the upper limit, the compatibility with other thermoplastic resins is excellent, and the molded product has a better molded appearance. In addition, the flowability of the thermoplastic resin composition and the ease of wiping off fingerprints on the molded product are also excellent.

[0015] The Mw of the graft copolymer (B) is preferably 1,000 to 1,000,000, more preferably 10,000 to 500,000, and even more preferably 20,000 to 300,000. When the Mw of the copolymer (A) is not less than the above lower limit, the handleability is superior, and when it is not more than the above upper limit, the effect of imparting fingerprint resistance is superior.

[0016] When the graft copolymer (B) is subjected to differential scanning calorimetry under the conditions of heating from 35°C to 200°C at a heating rate of 10°C / min in a nitrogen atmosphere, cooling to -100°C, and heating again to 200°C, a Tg of 1 or more is observed in the range of -100°C to less than 90°C and in the range of 90°C or more. In other words, a Tg of -100°C to less than 90°C (hereinafter referred to as "Tg 1 "), and a Tg of 90°C or higher (hereinafter referred to as "Tg 2 "). Tg 1 The temperature is preferably from -100 to 90°C, and more preferably from -90 to 70°C. Tg 2 The temperature is preferably 90°C or higher, and more preferably 90 to 150°C. Tg 1 and Tg 2 Difference from (Tg 2 -Tg 1 ) is preferably 10 to 250°C, more preferably 50 to 200°C. 1 and Tg 2 When calculating the difference between Tg 1 If there are two or more, the highest Tg 1 The value of Tg 2If there are two or more, the lowest Tg 2 The value of is adopted.

[0017] The Tg of the graft copolymer (B) can be adjusted by the Tg of the copolymer (A), the composition and molecular weight of the vinyl monomer (Y), and the like. Copolymer (A) contains a structural unit based on (meth)acrylate (a) having a linear or branched hydrocarbon group having 11 or more carbon atoms, and therefore tends to have a low Tg. On the other hand, vinyl monomer (Y) contains a specific vinyl monomer, and therefore the Tg of the polymer portion polymerized with vinyl monomer (Y) tends to be higher than that of copolymer (A). 1 The Tg of the polymer portion in which the vinyl monomer (Y) is polymerized is set to be approximately equal to the desired Tg 2 By selecting the vinyl monomer (Y) so that the Tg 1 and Tg 2 and The Tg of the copolymer (A) can be adjusted by the number of carbon atoms and structure of the hydrocarbon group in the (meth)acrylate (a), the proportion of the (meth)acrylate (a), the type and proportion of vinyl monomers other than the (meth)acrylate (a), the molecular weight, etc.

[0018] <Copolymer (A)> The copolymer (A) contains a structural unit based on a (meth)acrylate (a) having a linear or branched hydrocarbon group having 11 or more carbon atoms (hereinafter also referred to as "(meth)acrylate (a) unit") and a structural unit based on a vinyl monomer (X) other than the (meth)acrylate (a) (hereinafter also referred to as "vinyl monomer (X) unit"). The copolymer (A) may further contain a structural unit based on a crosslinking agent (hereinafter also referred to as a "crosslinking agent unit"). The (meth)acrylate (a), the vinyl monomer (X), and the crosslinking agent will be described in detail later.

[0019] The ratio of the (meth)acrylate (a) units to the total of 100 parts by mass of all the structural units constituting the copolymer (A) is 10 to 70 parts by mass, more preferably 20 to 65 parts by mass, and even more preferably 25 to 60 parts by mass. When the ratio of the (meth)acrylate (a) units is equal to or more than the above lower limit, the molded article or coating film containing the graft copolymer (B) has better fingerprint resistance, and when it is equal to or less than the above upper limit, the handleability is better. The total of all the structural units constituting the copolymer (A) is the total of the (meth)acrylate (a) units, the vinyl monomer (b) units and the crosslinking agent units.

[0020] The proportion of vinyl monomer (X) units relative to the total of 100 parts by mass of all structural units constituting copolymer (A) is preferably 30 to 90 parts by mass, more preferably 35 to 80 parts by mass, and even more preferably 40 to 75 parts by mass. When the proportion of vinyl monomer (X) units is equal to or more than the lower limit, the handleability is better, and when it is equal to or less than the upper limit, the effect of imparting fingerprint resistance is better.

[0021] The ratio of the crosslinking agent unit to the total of 100 parts by mass of all the structural units constituting the copolymer (A) is preferably 0 to 1.0 part by mass, more preferably 0 to 0.7 parts by mass, and even more preferably 0 to 0.1 parts by mass. If the ratio of the crosslinking agent unit is equal to or less than the upper limit, the molded article has better molded appearance and fingerprint resistance. In addition, the thermoplastic resin composition has better fluidity, and the molded article has better ease of wiping off fingerprints. Incidentally, the proportion of the crosslinking agent unit being 0 parts by mass means that no crosslinking agent unit is contained.

[0022] The copolymer (A) preferably has a polymerizable unsaturated bond at the end of the main chain. When the copolymer (A) has a polymerizable unsaturated bond at the end of the main chain, the fingerprint resistance and molded appearance of the molded product are improved. This is believed to be because the polymerizable unsaturated bond serves as a grafting point, chemically bonding the copolymer (A) with the polymer obtained by polymerizing the vinyl monomer (Y).

[0023] The copolymer (A) having a polymerizable unsaturated bond at the main chain end can be obtained, for example, by using α-methylstyrene dimer as a chain transfer agent when polymerizing the (meth)acrylate (a) and the vinyl monomer (X). 2 -C(Ph)=CH 2 A copolymer having a structure represented by the following formula (wherein Ph is a phenyl group) at the end of the main chain is obtained.

[0024] The toluene insoluble content of the copolymer (A) is preferably 70% by mass or less, more preferably 50% by mass or less, and particularly preferably 0% by mass, based on 100% by mass of the copolymer (A). If the toluene insoluble content of the copolymer (A) is the above upper limit or less, the toluene insoluble content of the graft copolymer (B) can be easily adjusted to the above-mentioned preferable upper limit or less.

[0025] The Mw of the copolymer (A) is preferably 5,000 to 500,000, more preferably 8,000 to 300,000, and even more preferably 10,000 to 200,000. When the Mw of the copolymer (A) is not less than the above lower limit, the handleability is better, and when it is not more than the above upper limit, the effect of imparting fingerprint resistance is better.

[0026] The copolymer (A) typically has a Tg. When the copolymer (A) has a Tg, the Tg of the copolymer (A) is preferably −100 to 90° C., more preferably −90 to 70° C. When the Tg of the copolymer (A) is within the above range, the Tg of the graft copolymer (B) is 1 It is likely to have the following characteristics.

[0027] The copolymer (A) is produced by a known method such as bulk polymerization, solution polymerization, bulk suspension polymerization, suspension polymerization, emulsion polymerization, etc. Among these, emulsion polymerization is preferred from the viewpoint of easy control of the particle size of the copolymer (A) particles. Among the emulsion polymerizations, mini-emulsion polymerization is preferred from the viewpoint of easy narrowing of the particle size distribution of the copolymer (A) particles.

[0028] The emulsion polymerization method for producing the copolymer (A) may be, for example, a method in which (meth)acrylate (a), vinyl monomer (X), water, an emulsifier, and optionally other additives (polymerization initiator, chain transfer agent, crosslinking agent) are mixed, the resulting mixture is emulsified, and the resulting emulsion is heated to polymerize the vinyl monomer, thereby obtaining an aqueous dispersion containing the copolymer (A).

[0029] Examples of the emulsifier include anionic surfactants, cationic surfactants, nonionic surfactants, and amphoteric surfactants, and anionic surfactants are preferred. Examples of the anionic surfactant include alkali metal salts of fatty acids (e.g., oleic acid, palmitic acid, stearic acid, rosin acid, etc.), alkali metal salts of alkenyl succinic acid, sodium alkylbenzene sulfonate, sodium alkylsulfosuccinate, and sodium polyoxyethylene nonylphenyl ether sulfate. One type of emulsifier may be used alone, or two or more types may be used in combination. The amount of the emulsifier to be added is, for example, 0.01 to 5.0 parts by mass relative to 100 parts by mass of the total of the (meth)acrylate (a), the vinyl monomer (X), and the crosslinking agent.

[0030] Examples of the polymerization initiator include an azo compound-based polymerization initiator, an organic peroxide-based polymerization initiator, and an inorganic peroxide-based polymerization initiator. As the azo compound-based polymerization initiator, the organic peroxide-based polymerization initiator, and the inorganic peroxide-based polymerization initiator, known initiators can be used without limitation. The polymerization initiator may be used alone or in combination of two or more. The amount of the polymerization initiator to be added is, for example, 0.1 to 5.0 parts by mass with respect to 100 parts by mass of the total of the (meth)acrylate (a), the vinyl monomer (X), and the crosslinking agent.

[0031] Examples of the chain transfer agent include mercaptans such as octyl mercaptan, n- or t-dodecyl mercaptan, n-hexadecyl mercaptan, and n- or t-tetradecyl mercaptan; α-methylstyrene dimer; terpenes, etc. The amount of the chain transfer agent added is, for example, 0.1 to 5.0 parts by mass per 100 parts by mass of the total of the (meth)acrylate (a), the vinyl monomer (X), and the crosslinking agent.

[0032] An example of the emulsification method is a method in which the mixture is treated with a homogenizer. Examples of the homogenizer include a pressure homogenizer and an ultrasonic homogenizer. In the pressure homogenizer, the mixed liquid is pressurized by using a pump or the like and is collided with a homogenizing valve to refine the monomer particles in the mixed liquid. In the pressure homogenizer, the pressure applied to the mixed liquid is not particularly limited and can be, for example, 1 to 100 MPa. In an ultrasonic homogenizer, ultrasonic vibration is applied to the mixture to generate minute vacuum bubbles inside the mixture. The impact generated when the vacuum bubbles bursts micronizes the monomer particles in the mixture. In an ultrasonic homogenizer, the amplitude of the ultrasonic vibration applied to the mixture is not particularly limited, and can be, for example, 10 to 17,000 μm. As the homogenizer, a continuous homogenizer that continuously processes the mixed liquid is usually used, but a batch homogenizer that processes any amount of the mixed liquid at a time may also be used.

[0033] The volume average particle diameter of the dispersed particles in the emulsion is preferably 10 to 1000 nm, more preferably 50 to 500 nm. If the volume average particle diameter of the emulsified particles in the emulsion is within the above range, the volume average particle diameter of the dispersed particles in the obtained aqueous dispersion of copolymer (A) is likely to be within the above range as well. Note that the mini-emulsion is an emulsion in which the volume average particle diameter of the emulsified particles is 1000 nm or less. The polymerization conditions are not particularly limited, but are, for example, 50 to 80° C. and 0.5 to 24 hours.

[0034] The resulting aqueous dispersion of copolymer (A) is usually used as it is for producing graft copolymer (B). The volume average particle diameter of the dispersed particles in the aqueous dispersion of the copolymer (A) is preferably 10 to 1000 nm, more preferably 50 to 500 nm. When the volume average particle diameter is equal to or more than the lower limit, the handleability is good, and when it is equal to or less than the upper limit, the stability of the emulsion is good.

[0035] "(Meth)acrylate (a)" The number of carbon atoms in the linear or branched hydrocarbon group of the (meth)acrylate (a) is 11 or more, preferably 12 or more, and more preferably 16 or more. The upper limit of the number of carbon atoms in the hydrocarbon group is not particularly limited, but is, for example, 50. When the number of carbon atoms in the hydrocarbon group is 11 or more, the lipophilicity of the surface of a molded article or coating film containing the graft copolymer (B) is improved, and fingerprints attached thereto become less noticeable. The hydrocarbon group may be straight-chain or branched, with the straight-chain being preferred from the standpoint of availability of raw materials. Examples of the hydrocarbon group include an alkyl group, an alkenyl group, an isoalkyl group, etc. Among these, the alkyl group is preferred from the viewpoint of imparting fingerprint resistance.

[0036] An example of the (meth)acrylate (a) is a compound represented by the following formula (1). CH 2 =CR 1 -C(=O)-OR 2 (1) However, R 1 is a hydrogen atom or a methyl group, R 2 is a straight-chain or branched hydrocarbon group having 11 or more carbon atoms. R 2 Examples of the hydrocarbon group include the same as those mentioned above.

[0037] Specific examples of the (meth)acrylate (a) include dodecyl (meth)acrylate, dodecenyl (meth)acrylate, tetradecyl (meth)acrylate, tetradecenyl (meth)acrylate, hexadecyl (meth)acrylate, hexadecenyl (meth)acrylate, octadecyl (meth)acrylate (also known as stearyl (meth)acrylate), octadecenyl (meth)acrylate, isostearyl (meth)acrylate, behenyl (meth)acrylate, etc. These (meth)acrylates (a) may be used alone or in combination of two or more. As the (meth)acrylate (a), stearyl (meth)acrylate and isostearyl (meth)acrylate are preferred from the viewpoints of the effect of imparting fingerprint resistance and the ease of availability of raw materials.

[0038] "Vinyl monomer (X)" The vinyl monomer (X) may be any monomer capable of copolymerizing with the (meth)acrylate (a), and examples thereof include (meth)acrylates (b) having at least one of a linear or branched hydrocarbon group having 1 to 10 carbon atoms, an alicyclic group, and an aromatic group, an aromatic vinyl (c), a vinyl cyanide (d), maleic anhydride (e), and a maleimide compound (f). The vinyl monomer (X) may further contain other vinyl monomers other than those mentioned above, if necessary.

[0039] In the (meth)acrylate (b), examples of the linear or branched hydrocarbon group include an alkyl group, an alkenyl group, and an isoalkyl group. The alicyclic group may be monocyclic or polycyclic. The alicyclic group has, for example, 4 to 10 carbon atoms. Examples of the aromatic group include aryl groups such as a phenyl group, and aralkyl groups such as a benzyl group.

[0040] Specific examples of the (meth)acrylate (b) include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, i-propyl (meth)acrylate, n-butyl (meth)acrylate, i-butyl (meth)acrylate, t-butyl (meth)acrylate, amyl (meth)acrylate, isoamyl (meth)acrylate, octyl (meth)acrylate, dodecyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, decyl (meth)acrylate, cyclohexyl (meth)acrylate, benzyl (meth)acrylate, phenyl (meth)acrylate, adamantyl (meth)acrylate, and glycidyl (meth)acrylate.

[0041] Examples of the aromatic vinyl (c) include styrene, α-methylstyrene, o-, m- or p-methylstyrene, vinylxylene, pt-butylstyrene and ethylstyrene. Examples of the vinyl cyanide (d) include acrylonitrile and methacrylonitrile.

[0042] Examples of the maleimide compound (f) include N-alkylmaleimides such as N-methylmaleimide, N-ethylmaleimide, Nn-propylmaleimide, Ni-propylmaleimide, Nn-butylmaleimide, Ni-butylmaleimide, and N-tert-butylmaleimide; N-cycloalkylmaleimides such as N-cyclohexylmaleimide; N-arylmaleimides such as N-phenylmaleimide, N-(2-methylphenyl)maleimide, N-(4-hydroxyphenyl)maleimide, and N-chlorophenylmaleimide; and N-aralkylmaleimides. These vinyl monomers may be used alone or in combination of two or more.

[0043] From the viewpoint of availability of raw materials, the vinyl monomer (X) is preferably at least one selected from the group consisting of (meth)acrylates (b), aromatic vinyls (c) and vinyl cyanides (d). Among the above, from the viewpoint of reactivity with the (meth)acrylate (a), the (meth)acrylate (b) is preferred, and from the viewpoint of compatibility with the thermoplastic resin, the aromatic vinyl (c) and the vinyl cyanide (d) are preferred. For example, when the vinyl monomer (X) is composed of an aromatic vinyl (c) and a vinyl cyanide (d), the aromatic vinyl (c) preferably accounts for 60 to 90 mass% and the vinyl cyanide (d) for 10 to 40 mass%, and more preferably the aromatic vinyl (c) for 65 to 80 mass% and the vinyl cyanide (d) for 20 to 35 mass%, based on the total mass of the vinyl monomer (X).

[0044] "Cross-linking agent" Examples of crosslinking agents include allyl (meth)acrylate, butylene di(meth)acrylate, ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, 1,3-butylene glycol di(meth)acrylate, 1,4-butylene glycol di(meth)acrylate, triallyl cyanurate, triallyl isocyanurate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, polybutylene glycol di(meth)acrylate, polyester di(meth)acrylate, polyurethane di(meth)acrylate, polybutadiene di(meth)acrylate, polyglycerin poly(meth)acrylate, divinylbenzene, etc. These crosslinking agents may be used alone or in combination of two or more.

[0045] <Vinyl monomer (Y)> The vinyl monomer (Y) contains at least one vinyl monomer selected from the group consisting of (b) (meth)acrylate having at least one of a linear or branched hydrocarbon group having 1 to 10 carbon atoms, an alicyclic group, and an aromatic group, an aromatic vinyl (c), a vinyl cyanide (d), maleic anhydride (e), and a maleimide compound (f). By containing such a vinyl monomer, it is possible to increase the Tg of the polymer portion polymerized with the vinyl monomer (Y). Specific examples of the (meth)acrylate (b), aromatic vinyl (c), vinyl cyanide (d), maleic anhydride (e) and maleimide compound (f) are the same as those mentioned above. The vinyl monomer (Y) may further contain other vinyl monomers other than those mentioned above, if necessary. From the viewpoint of the handleability of the graft copolymer (B), it is preferable that the vinyl monomer (Y) does not contain a (meth)acrylate (a).

[0046] From the viewpoint of availability of raw materials, the vinyl monomer (Y) is preferably at least one selected from the group consisting of (meth)acrylates (b), aromatic vinyls (c) and vinyl cyanides (d). Among the above, when the graft copolymer (B) is mixed with a thermoplastic resin described later, it is preferable to select a composition that is easily dispersed in the thermoplastic resin. For example, when the thermoplastic resin is an ABS resin or an AS resin, it is preferable to select a combination of an aromatic vinyl and a vinyl cyanide compound, and when the thermoplastic resin is an acrylic resin, it is preferable to select a (meth)acrylate.

[0047] <Method for producing graft copolymer (B)> The graft copolymer (B) is obtained by graft polymerizing the vinyl monomer (Y) in the presence of the copolymer (A). During the graft polymerization, a chain transfer agent may be added to adjust the molecular weight of the graft copolymer (B). The graft polymerization method is not particularly limited, but an emulsion polymerization method is preferred.

[0048] An example of a method for producing the graft copolymer (B) by emulsion polymerization is to add a vinyl monomer (Y) and a polymerization initiator to an aqueous dispersion containing the copolymer (A), water, and an emulsifier, and polymerize the vinyl monomer (Y) by heating. This produces an aqueous dispersion containing the graft copolymer (B). The aqueous dispersion of the copolymer (A) can be obtained by the above-mentioned production method. The polymerization initiator may be the same as those mentioned above. The polymerization conditions are not particularly limited, but are, for example, 50 to 90° C. and 0.5 to 6 hours.

[0049] The volume average particle diameter of the dispersed particles in the aqueous dispersion of the graft copolymer (B) is preferably 10 to 1000 nm, more preferably 50 to 500 nm. When the volume average particle diameter is equal to or more than the lower limit, the handleability is good, and when it is equal to or less than the upper limit, the stability of the emulsion is good.

[0050] If necessary, the graft copolymer (B) is recovered from the aqueous dispersion of the graft copolymer (B), thereby obtaining a powder of the graft copolymer (B). Examples of the method for recovering the graft copolymer (B) include a precipitation method and a spray drying method. The precipitation method includes adding a precipitating agent to the aqueous dispersion, heating and stirring, separating the precipitating agent, and then washing, dehydrating, and drying the precipitated graft copolymer (B). Examples of the precipitating agent include aqueous solutions of sulfuric acid, acetic acid, calcium chloride, magnesium sulfate, etc.

[0051] The average particle size of the powder of the graft copolymer (B) is preferably 100 to 800 μm, more preferably 150 to 600 μm. When the average particle size is equal to or more than the lower limit, the powder is less prone to scattering and is easy to handle, and when the average particle size is equal to or less than the upper limit, the powder is easily dispersible in thermoplastic resins.

[0052] [Thermoplastic resin composition] A thermoplastic resin composition according to one embodiment of the present invention contains a graft copolymer (B) and a thermoplastic resin other than the graft copolymer (B) (hereinafter also referred to as "thermoplastic resin (C)"). The thermoplastic resin composition may contain additives as necessary within the range in which the effects of the present invention are not significantly impaired.

[0053] The thermoplastic resin (C) is not particularly limited, and examples thereof include copolymer (A), acrylic resin (e.g., PMMA resin), acrylonitrile-styrene copolymer (AS resin), acrylonitrile-α-methylstyrene copolymer (αSAN resin), styrene-maleic anhydride copolymer, acrylonitrile-styrene-N-substituted maleimide terpolymer, styrene-maleic anhydride-N-substituted maleimide terpolymer, resin obtained by graft polymerizing at least one vinyl monomer selected from the group consisting of aromatic vinyl, vinyl cyanide, and (meth)acrylate in the presence of rubbery polymer (e.g., polybutadiene, acrylic rubber, silicone rubber, ethylene propylene diene rubber (EPDM) or composite rubber thereof) (e.g., ABS resin, ASA resin, SAS resin, AES resin), polycarbonate resin, polybutylene terephthalate (PBT resin), poly Examples of the thermoplastic resin (C) include polyolefins such as polyethylene terephthalate (PET resin), polyvinyl chloride, polyethylene, and polypropylene, styrene-butadiene-styrene (SBS), styrene-butadiene (SBR), hydrogenated SBS, and styrene-isoprene-styrene (SIS) elastomers, various olefin elastomers, various polyester elastomers, polystyrene, methyl methacrylate-styrene copolymer (MS resin), acrylonitrile-styrene-methyl methacrylate 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), polyarylate, liquid crystal polyester resin, and polyamide resin (e.g., nylon). These thermoplastic resins (C) may be used alone or in combination of two or more.

[0054] Examples of additives include various stabilizers such as antioxidants and light stabilizers, lubricants, plasticizers, release agents, dyes, pigments (carbon black, etc.), antistatic agents, flame retardants, inorganic fillers, metal powders, and the like.

[0055] In the thermoplastic resin composition, the content of the graft copolymer (B) is preferably 1 to 80 parts by mass, and more preferably 5 to 50 parts by mass, per 100 parts by mass of the total of the graft copolymer (B) and the thermoplastic resin (C). When the content of the graft copolymer (B) is equal to or more than the above lower limit, the molded article of the thermoplastic resin composition has better fingerprint resistance, and when it is equal to or less than the above upper limit, the handleability is better.

[0056] The proportion of the (meth)acrylate (a) unit contained in the graft copolymer (B) relative to the total mass of the graft copolymer (B) and the thermoplastic resin (C) is preferably 1 to 56 mass%, more preferably 2 to 49 mass%. If the proportion of the (meth)acrylate (a) unit is not less than the above lower limit, the molded article has better fingerprint resistance, and if it is not more than the above upper limit, the molded article has better handleability.

[0057] The content of the additive is preferably from 0 to 100 parts by mass, and more preferably from 0 to 10 parts by mass, per 100 parts by mass of the total of the graft copolymer (B) and the thermoplastic resin (C).

[0058] The thermoplastic resin composition can be produced, for example, by mixing and dispersing the powder of the graft copolymer (B), the thermoplastic resin (C), and, if necessary, additives, using a V-type blender, a Henschel mixer, or the like, and melt-kneading the mixture thus obtained using a melt-kneading machine such as a screw extruder, a Banbury mixer, a pressure kneader, a mixing roll, or the like. If necessary, the melt-kneaded product obtained may be pelletized using a pelletizer, or the like.

[0059] [Molded product] A molded article according to one embodiment of the present invention contains the thermoplastic resin composition described above. The molded article of this embodiment can be obtained, for example, by molding the above-mentioned thermoplastic resin composition by a known molding method, such as injection molding, press molding, extrusion molding, vacuum molding, blow molding, etc. EXAMPLES

[0060] The present invention will be described in more detail below with reference to examples and comparative examples. However, the present invention is not limited to the following examples in any way as long as the gist of the present invention is not exceeded. In the following description, "parts" means "parts by mass" and "%" means "% by mass".

[0061] The abbreviations used below represent the following: (monomer) LMA: dodecyl methacrylate. CMA: hexadecyl methacrylate. SMA: stearyl methacrylate. i-SMA: isostearyl methacrylate. SA: stearyl acrylate. MMA: methyl methacrylate. MA: methyl acrylate. EHMA: 2-ethylhexyl methacrylate. ST: styrene. AN: Acrylonitrile. (Crosslinking agent) AMA: Allyl methacrylate. (Chain transfer agent) MSD: α-methylstyrene dimer. TDM: t-dodecyl mercaptan. (Polymerization initiator) LPO: Lauroyl peroxide. BHP: t-butyl hydroperoxide. (thermoplastic resin) PMMA: Polymethyl methacrylate ("ACRYPET VH5" manufactured by Mitsubishi Chemical). AS: Acrylonitrile-styrene copolymer produced by suspension polymerization ("UMG AXS Resin S102N" manufactured by Techno UMG). PC: Polycarbonate (Mitsubishi Engineering Plastics "Iupilon S-2000"). SX-006: Silicone-based core-shell composite rubber-type graft copolymer ("Metabrene SX-006" manufactured by Mitsubishi Chemical). (Coloring agent) CB: Carbon black.

[0062] [Measurement of toluene insolubles] The latex of the copolymer (copolymer (A) or graft copolymer (B)) was dried in a dryer at 60° C. for one day, washed with isopropanol, and dried in a vacuum dryer to recover the copolymer. 1 g (X) of the recovered copolymer was added to 20 mL of toluene and allowed to stand at room temperature (25°C) for 3 days, after which the resulting suspension or solution was centrifuged at 14,000 rpm for 180 minutes. If there was a precipitate after centrifugation, the precipitate and the supernatant solution (toluene solution) were separately collected. The precipitate was then thoroughly dried using a vacuum dryer, its mass Y (g) was measured, and the toluene insoluble content was calculated using the following formula. If there was no precipitate after centrifugation, the toluene insoluble content was taken as 0% by mass. Toluene insolubles (mass%) = (Y / X) x 100

[0063] [Measurement of weight average molecular weight] The latex of the copolymer (copolymer (A) or graft copolymer (B)) was recovered by the respective methods described below. 0.005 g of the recovered copolymer was stirred and dissolved in 10 g of tetrahydrofuran (THF) at room temperature (25°C). The solution was introduced into a GPC apparatus. The molecular weight of the polymer was measured in terms of polystyrene using a calibration curve obtained in advance using standard polystyrene with known molecular weight, and Mw was calculated. When the copolymer (A) or the graft copolymer (B) was not dissolved in THF, the supernatant was collected and measured.

[0064] [Measurement of glass transition temperature] A part of the latex of the copolymer (copolymer (A) or graft copolymer (B)) was washed with isopropanol and dried in a vacuum dryer. The obtained powder was subjected to differential scanning calorimetry (DSC) under a nitrogen atmosphere under the conditions of heating from 35°C to 200°C at a heating rate of 10°C / min, cooling to -100°C, and then heating again to 200°C, and the glass transition temperature (°C) observed was determined.

[0065] [Measurement of volume average particle size] The volume average particle size (nm) of the latex of the copolymer (copolymer (A) or graft copolymer (B)) was determined by dynamic light scattering using Nanotrac UPA-EX150 manufactured by Nikkiso Co., Ltd.

[0066] [Evaluation of molded appearance] The produced compact was subjected to the following procedure: * , a * , b * The 60° gloss was measured and the image clarity was evaluated.

[0067] <L * , a * , b * Measurements > Using a spectrophotometer (Konica Minolta Optips "CM-3500d"), the L of the surface of the molded body was measured using the SCE method. * was measured. * The lower the value, the darker the black color (higher jet blackness) and the better the molded appearance was judged to be. "L * " is the L standard adopted in JIS Z 8729. * a * b * It means the brightness of the color values ​​in the color system. The "SCE method" refers to a method of measuring color using a spectrophotometer conforming to JIS Z 8722 and removing specular light using a light trap.

[0068] <60° Gloss Measurement> Using a Suga Test Instruments "Digital Variable Gloss Meter UGV-5D," the reflectance (%) of the surface of the molded product at an incident angle and reflection angle of 60° was measured in accordance with JIS K 7105, and the value was taken as the 60° gloss. The higher the 60° gloss value, the higher the surface gloss and the better the molded appearance was judged to be.

[0069] <Evaluation of image clarity> Image sharpness (image clarity) was evaluated in accordance with JIS K 7374:2007. The measurement was performed using a Suga Test Instruments "Image Clarity Measurement Instrument ICM-1DP," with a measurement angle of 60 degrees and a reading of an optical comb width of 1.0 mm.

[0070] <Judgment> From the above results, the appearance of the molded product was judged according to the following criteria. ◎:L * is less than 5, the 60° gloss value is 85% or more, and the sharpness is 95% or more. ○:L * The color must meet one to three of the following criteria: value is 5 or more and less than 7, 60° gloss value is 80% or more and less than 85%, and image sharpness is 90% or more and less than 95%, and the rest of the criteria meet the above criteria. △:L * The material satisfies 1 to 3 of the following criteria: value is 7 or more and less than 10, 60° gloss value is 75% or more and less than 80%, and image sharpness is 85% or more and less than 90%, and the rest satisfy the above criteria. ×:L * It satisfies 1 to 3 of the following criteria: 10 or more, 60° gloss value less than 75%, and sharpness less than 85%.

[0071] [Evaluation of molded appearance after fingerprints are attached] The thumb of the right hand was pressed against the surface of the molded article for evaluation of its appearance for 10 seconds to leave a fingerprint. The fingerprints were removed in the same manner as above. * , a * , b * The 60° gloss was measured and the image clarity was evaluated. L before and after fingerprints * , a * , b *From the 60° gloss and distinctness, ΔEab, gloss retention and distinctness retention were calculated according to the following formula. ΔEab={(L after attachment * -L before attachment * ) 2 + (a after attachment * -a before attachment * ) 2 +(b after attachment * -b before attachment * ) 2} 1 / 2 Gloss retention rate (%) = 60° gloss after application (%) / 60° gloss before application (%) x 100 Image sharpness retention rate (%) = Image sharpness after application (%) / Image sharpness before application (%) x 100

[0072] The evaluation was made based on ΔEab, gloss retention and image sharpness retention according to the following criteria. <Evaluation criteria> ⊚: ΔEab is 1 or less, gloss retention is 90% or more, sharpness retention is 90% or more, and fingerprints are barely noticeable. ◯: ΔEab is greater than 1 and less than 2, gloss retention is 80% or greater and less than 90%, and image sharpness retention is 85% or greater and less than 90%, and the rest meet the above ◎ criteria; fingerprints are not easily noticeable. △: ΔEab is greater than 2 and less than 3, gloss retention is 70% or greater and less than 80%, and image sharpness retention is 80% or greater and less than 85%. The rest of the criteria are met as above for ◎ or ○, and fingerprints are slightly visible. ×: One to three of the following conditions are met: ΔEab is greater than 3, gloss retention is less than 70%, and image sharpness retention is less than 85%, and fingerprints are quite noticeable.

[0073] [Evaluation of the number of wipes required until artificial dirt becomes unnoticeable] The surface of a rubber stopper with a diameter of 2.5 cm was roughened with abrasive paper #240. Artificial grime (manufactured by Isekyu Co., Ltd., JIS C 9606 compliant) was dropped onto an ink pad for application, and the above-mentioned rubber stopper was pressed against it, and then the ink pad was pressed against the surface of the molded product to adhere the artificial grime. The surface of the molded article to which the artificial dirt had been attached was wiped off until the artificial dirt was no longer noticeable, using the same method as in the evaluation of the appearance of the molded article after wiping, which will be described later. Whether the artificial dirt was no longer noticeable was judged by visual inspection. The number of times the artificial dirt was wiped off until it became unnoticeable was judged according to the following criteria. ◎: Wipe less than two times. ○: Wipe 3 to 6 times. △: Number of wipes: 7 to 9 times. ×: Wiping was performed 10 or more times.

[0074] [Evaluation of molded appearance after wiping] The fingerprints were wiped off from the surfaces of the molded articles on which fingerprints had been left in the evaluation of molded appearance after fingerprints were left as described above, in the following manner. As shown in Fig. 1, a rod-shaped jig 10 with a hemispherical tip 11 was prepared, and the tip 11 was covered with a microfiber cloth 12. The tip 11 covered with the microfiber cloth 12 was brought into contact with the surface of a test piece 13 so that the rod-shaped jig 10 was perpendicular to the surface of the test piece 13, and the tip 11 was slid back and forth horizontally (in the direction of the arrow in the figure) on the surface of the molded article 13 100 times. At this time, the load applied was 500 g.

[0075] For the area where the fingerprints were wiped off, repeat the procedure above. * , a * , b * The 60° gloss was measured and the image clarity was evaluated. L before and after fingerprints were removed * , a * , b * From the 60° gloss and distinctness, ΔEab, gloss retention and distinctness retention were calculated according to the following formula. ΔEab={(L after wiping * -L before attachment * ) 2 +(a after wiping * -a before attachment * ) 2 +(b after wiping * -b before attachment * ) 2} 1 / 2 Gloss retention rate (%) = 60° gloss after wiping (%) / 60° gloss before application (%) x 100 Image sharpness retention rate (%) = Image sharpness after wiping (%) / Image sharpness before adhesion (%) x 100

[0076] The evaluation was made based on ΔEab, gloss retention and image sharpness retention according to the following criteria. <Evaluation criteria> ⊚: ΔEab is 1 or less, gloss retention is 90% or more, sharpness retention is 90% or more, and fingerprints are barely noticeable. ◯: ΔEab is greater than 1 and less than 2, gloss retention is 80% or greater and less than 90%, and image sharpness retention is 85% or greater and less than 90%, and the rest meet the above ◎ criteria; fingerprints are not easily noticeable. △: ΔEab is greater than 2 and less than 3, gloss retention is 70% or greater and less than 80%, and image sharpness retention is 80% or greater and less than 85%. The rest of the criteria are met as above for ◎ or ○, and fingerprints are slightly visible. ×: One to three of the following conditions are met: ΔEab is greater than 3, gloss retention is less than 70%, and image sharpness retention is less than 80%, and fingerprints are quite noticeable.

[0077] [Evaluation of fluidity at 230℃] For pelletized thermoplastic resin compositions, the melt volume rate (MVR) (cm) was measured at 230°C in accordance with ISO 1133. 3 / 10 min) was measured with a load of 98 N (10 kg). The higher the MVR, the better the fluidity.

[0078] [Evaluation of gas adhesion] Using an injection molding machine (Toshiba Machine Co., Ltd., "IS55FP-1.5A"), a plate-shaped test piece (molded product) with a length of 100 mm, a width of 50 mm, and a thickness of 3 mm was molded from the pellet-shaped thermoplastic resin composition under the conditions of a cylinder setting temperature of 260°C and a mold temperature of 30°C, with the amount of resin filled reduced to about 2 / 3 of the mold internal volume, for 50 shots to make a short shot. A gas adsorption plate was placed in the mold, and the amount of gas adhering to the mold (gas adhering amount) was measured from the weight difference between the plate before the start of molding and after 50 shots of molding, and evaluated according to the following criteria. The smaller the amount of gas adhering, the less gas is generated during molding. ◎: Gas adhesion amount is 0.5 mg or less. ○: Gas adhesion amount is more than 0.5 mg and 0.7 mg or less. △: Gas adhesion amount is more than 0.7 mg and 0.9 mg or less. ×: Gas adhesion amount exceeds 0.9 mg.

[0079] [Production of copolymer (A)] <Production Example A-1: ​​Production of Copolymer (A-1)> A vessel was charged with 70 parts of stearyl methacrylate (SMA), 25 parts of methyl methacrylate (MMA), 5 parts of methyl acrylate (MA), 2 parts of α-methylstyrene dimer (MSD), and 1 part of lauroyl peroxide (LPO), to which was added a mixture of 360 parts of distilled water and 0.2 parts of dipotassium alkenyl succinate. The mixture was then treated twice with a pressure homogenizer (manufactured by Sanmaru Machinery Industry Co., Ltd.) at 30 MPa to obtain a pre-emulsion with a volume average particle size of 450 nm. The pre-emulsion was transferred to a reactor equipped with a reagent injection vessel, a cooling tube, a jacket heater, and a stirrer, and the atmosphere was replaced with nitrogen. The mixture was then heated to 60°C with stirring to initiate radical polymerization, and then aged at 80°C for 5 hours to complete the polymerization. This resulted in a latex of copolymer (A-1). The solid content of the resulting latex was 21%, the amount of coagulum was 0.03%, and the volume average particle size was 450 nm, the same as that of the pre-emulsion. A part of the obtained latex was washed with isopropanol and dried in a vacuum dryer to obtain a powder of copolymer (A-1). When the obtained powder was subjected to DSC, a glass transition temperature was observed at 0°C.

[0080] <Production Examples A-2 to A-20: Production of Copolymers (A-2) to (A-20)> Except for changing the types and amounts of (meth)acrylate (a), vinyl monomer (X), chain transfer agent, and polymerization initiator as shown in Tables 1 to 3, the same procedure as in Production Example (A-1) was performed to obtain latexes and powders of each of the copolymers (A-2) to (A-20).

[0081] <Production Example A-21: Production of Copolymer (A-21)> A vessel was charged with 50 parts of stearyl methacrylate (SMA), 45 parts of methyl methacrylate (MMA), 5 parts of methyl acrylate (MA), 2 parts of t-dodecyl mercaptan (TDM), and 0.5 parts of t-butyl hydroperoxide (BHP), to which was added a mixture of 360 parts of distilled water and 0.2 parts of dipotassium alkenyl succinate. The mixture was then treated twice with a pressure homogenizer (manufactured by Sanmaru Machinery Co., Ltd.) at 30 MPa to obtain a pre-emulsion with a volume average particle size of 300 nm. The pre-emulsion was transferred to a reactor equipped with a reagent injection vessel, a cooling tube, a jacket heater, and a stirrer, and the atmosphere was replaced with nitrogen. The mixture was then heated to 60°C with stirring, and 0.001 parts of ferrous sulfate, 0.003 parts of disodium ethylenediaminetetraacetate, and 0.3 parts of sodium formaldehyde sulfoxylate were added to initiate radical polymerization. The mixture was then aged at 80°C for 5 hours to complete the polymerization. This resulted in the production of a latex of copolymer (A-21). The solid content of the resulting latex was 22%, the amount of agglomerates was 0.02%, and the volume average particle size was 100 nm, which was smaller than that of the pre-emulsion.

[0082] <Production Examples A-22 to A-24: Production of Copolymers (A-22) to (A-24)> The amount of methyl methacrylate (MMA) was changed as shown in Table 3, and the amount of allyl methacrylate (AMA) shown in Table 3 was added together with MMA, etc., in the same manner as in Production Example (A-4), to obtain latex and powder of each of the copolymers (A-22) to (A-24).

[0083] Tables 1 to 3 show the evaluation results of the copolymers (A-1) to (A-24). Also, a portion of the copolymers (A-5) and (A-13) was recovered by the following procedure. 100 parts of 1.5wt% aqueous sulfuric acid solution was heated to 80℃, and while stirring the aqueous solution, 100 parts of the latex of copolymer (A-5) or (A-13) was gradually dropped into the aqueous solution to solidify copolymer (A-5) and (A-13). Since the solidification temperature and drying temperature of both were higher than the glass transition temperature, the solidified material was fused and became a large mass. Next, the solidified material was dehydrated, washed, dried, and then crushed with a crusher to obtain powdered copolymer (A-5) and (A-13).

[0084] [Table 1]

[0085] [Table 2]

[0086] [Table 3]

[0087] [Production of Graft Copolymer (B)] <Production Example B-1: Production of Graft Copolymer (B-1)> The raw materials were charged in the following proportions into a reactor equipped with a reagent injection vessel, a cooling tube, a jacket heater, and a stirrer. The atmosphere inside the reactor was thoroughly replaced with nitrogen, and the internal temperature was then raised to 70°C with stirring. [Composition] Water (including water in copolymer latex) 200 parts Copolymer (A-1) latex 50 parts (solid content) Dipotassium alkenyl succinate 1 part Sodium formaldehyde sulfoxylate 0.3 parts Ferrous sulfate 0.001 parts Disodium ethylenediaminetetraacetate 0.003 parts

[0088] Next, a mixed liquid containing methyl methacrylate (MMA), methyl acrylate (MA), and t-butyl hydroperoxide (BHP) in the following ratio was added dropwise over 100 minutes while the temperature was raised to 80°C. [Composition] Methyl methacrylate 45 parts Methyl acrylate 5 parts 0.3 parts t-butyl hydroperoxide

[0089] After the dropwise addition, the mixture was kept at 80° C. for 30 minutes and then cooled to obtain a latex of graft copolymer (B-1). The solid content of the obtained latex was 33%, the amount of coagulum was 0.1%, and the volume average particle size was 400 nm.

[0090] Next, 100 parts of 1.5 wt% sulfuric acid aqueous solution was heated to 80°C, and while stirring the aqueous solution, 100 parts of graft copolymer (B-1) latex was gradually dropped into the aqueous solution to solidify the graft copolymer (B-1), and the temperature was further increased to 95°C and maintained for 10 minutes. The solidified product was then dehydrated, washed, and dried to obtain a powder of graft copolymer (B-1).

[0091] <Production Example: Graft Copolymers (B-2) to (B-31)> Graft copolymer powders (B-2) to (B-31) were obtained in the same manner as in Production Example B-1, except that the type and amount of copolymer latex and the type and amount of vinyl monomer (Y) were changed as shown in Tables 4 to 7.

[0092] Tables 4 to 7 show the evaluation results of the graft copolymers (B-1) to (B-31).

[0093] [Table 4]

[0094] [Table 5]

[0095] [Table 6]

[0096] [Table 7]

[0097] [Examples 1 to 31, Comparative Examples 1 to 7] <Preparation of Thermoplastic Resin Composition> According to the formulations shown in Tables 8 to 11, powder of the copolymer (A) or graft copolymer (B), the thermoplastic resin (C), and carbon black (CB) were mixed using a Henschel mixer, and the mixture was fed into an extruder heated to 240°C and kneaded to obtain pellets of a thermoplastic resin composition.

[0098] <Preparation of molded products for evaluation> Using pellets of the above thermoplastic resin composition, a plate-shaped molded product having a length of 100 mm, a width of 100 mm, and a thickness of 3 mm was produced in a 4-ounce injection molding machine (manufactured by Japan Steel Works) under conditions of a cylinder temperature of 240°C, a mold temperature of 60°C, and an injection rate of 20 g / s. Tables 8 to 11 show the evaluation results of the molded products.

[0099] [Table 8]

[0100] [Table 9]

[0101] [Table 10]

[0102] [Table 11]

[0103] In Tables 8 to 11, the "(meth)acrylate (a) content" is the proportion (mass%) of (meth)acrylate (a) units contained in the graft copolymer (B) relative to the total mass of the thermoplastic resin contained in the thermoplastic resin composition, and was calculated by [proportion (mass%) of graft copolymer (B) relative to the total mass of the thermoplastic resin] × [proportion (mass%) of (meth)acrylate (a) relative to the total mass of all vinyl monomers and crosslinking agents in the graft copolymer (B)] / 100. The ratio of (meth)acrylate (a) to the total mass of all vinyl monomers and crosslinking agent in the graft copolymer (B) was calculated by {[Ratio of copolymer (A) to the total mass of copolymer (A) and vinyl monomer (Y) (mass %)] / 100}×{[Ratio of (meth)acrylate (a) to the total mass of (meth)acrylate (a), vinyl monomer (X), and crosslinking agent (mass %)] / 100}×100.

[0104] The results of each of the Examples and Comparative Examples reveal the following. The thermoplastic resin compositions of Examples 1 to 31 using the graft copolymers (B-1) to (B-17) and (B-22) to (B-30) were excellent in molded appearance, inconspicuousness of fingerprints (molded appearance after fingerprints are attached), and ease of wiping off fingerprints (molded appearance after fingerprints are wiped off). They also had good fluidity. In particular, Examples 1 to 30 were excellent in ease of wiping off artificial dirt. Examples 1 to 19 and 22 to 31 also suppressed gas generation during molding. On the other hand, the thermoplastic resin compositions of Comparative Examples 1 to 3 using graft copolymers (B-18) to (B-20) in which the ratio of (meth)acrylate (a) in copolymer (A) was outside the range of 10 to 70 parts by mass were insufficient in at least one of the following: molded appearance, inconspicuousness of fingerprints, and ease of wiping off fingerprints. In addition, there were cases where artificial dirt was difficult to wipe off, and cases where a large amount of gas was generated during molding. The thermoplastic resin composition of Comparative Example 4, which used the graft copolymer (B-21) that did not have a glass transition temperature in the range of -100°C or more and less than 90°C, had poor molded appearance. This is believed to be due to insufficient compatibility between the graft copolymer (B-21) and the thermoplastic resin. The thermoplastic resin compositions of Comparative Examples 5 and 6, which used the copolymers (A-13) and (A-5) without grafting, had poor molded appearances, presumably due to insufficient compatibility between the copolymers (A-13) and (A-5) and the thermoplastic resin. The thermoplastic resin composition of Comparative Example 7, which used the graft copolymer (B-31) that did not have a glass transition temperature in the region of 90° C. or higher, had poor molded appearance. In addition, the artificial dirt was difficult to wipe off, and a large amount of gas was generated during molding. [Industrial Applicability]

[0105] The graft copolymer of the present invention can impart excellent fingerprint resistance to molded articles. Molded articles of thermoplastic resin compositions containing the graft copolymer of the present invention have excellent lipophilicity, so fingerprints are less noticeable when they are attached to the articles. In addition, fingerprints attached to the articles are easily wiped off. Furthermore, molded articles made from thermoplastic resin compositions containing the graft copolymers of the present invention also have excellent molded appearance. By simply mixing the graft copolymer of the present invention with a thermoplastic resin (C), a molded article having excellent fingerprint resistance and molded appearance can be obtained, which leads to omitting the step of painting the molded article. The thermoplastic resin composition and molded article of the present invention are useful as various industrial materials for forming parts that are likely to be touched by people's hands, such as around car navigation systems and switches, and housings for televisions, audio equipment, and electronic devices.

Claims

1. a graft copolymer obtained by graft polymerizing a vinyl monomer (Y) in the presence of the copolymer (A), the copolymer (A) comprises a structural unit based on a (meth)acrylate (a) having a linear or branched hydrocarbon group having 11 or more carbon atoms, and a structural unit based on a vinyl monomer (X) other than the (meth)acrylate (a); the ratio of the structural unit based on the (meth)acrylate (a) to the total of 100 parts by mass of all structural units constituting the copolymer (A) is 10 to 70 parts by mass, the vinyl monomer (Y) comprises at least one selected from the group consisting of (b) (meth)acrylate having at least one of a linear or branched hydrocarbon group having 1 to 10 carbon atoms, an alicyclic group, and an aromatic group, (c) aromatic vinyl, (d) vinyl cyanide, (e) maleic anhydride, and (f) maleimide compound, A graft copolymer, wherein when differential scanning calorimetry is performed under conditions of heating from 35°C to 200°C at a heating rate of 10°C / min in a nitrogen atmosphere, cooling to -100°C, and heating again to 200°C, one or more glass transition temperatures are observed in each of the range of -100°C to 80°C and the range of 90°C or higher.

2. The graft copolymer described in claim 1, wherein the difference (Tg2-Tg1) between the glass transition temperature (Tg1) observed in the range of -100°C or more and 80°C or less and the glass transition temperature (Tg2) observed in the range of 90°C or more is 10°C or more and 250°C or less.

3. 3. The graft copolymer according to claim 1, wherein the copolymer (A) has a polymerizable unsaturated bond at an end of the main chain.

4. The graft copolymer according to any one of claims 1 to 3, wherein the ratio of the copolymer (A) to the total of 100 parts by mass of the copolymer (A) and the vinyl monomer (Y) is 10 to 80 parts by mass.

5. The graft copolymer according to any one of claims 1 to 4, wherein the toluene-insoluble matter is 50% by mass or less.

6. The copolymer (A) contains a structural unit based on a crosslinking agent in a ratio of 0 to 1.0 part by mass per 100 parts by mass of all structural units constituting the copolymer (A). The graft copolymer according to any one of claims 1 to 5.

7. The graft copolymer according to any one of claims 1 to 6, which has a weight average molecular weight of 1,000 to 1,000,000.

8. A thermoplastic resin composition comprising the graft copolymer according to any one of claims 1 to 7 and another thermoplastic resin.

9. A molded article comprising the thermoplastic resin composition according to claim 8.

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