Thermoplastic resin composition, resin molded article, and plated processed article

Abstract

A thermoplastic resin composition comprising a melt blend of a rubber graft copolymer (A) and a copolymer (B), wherein the rubber graft copolymer (A) is copolymerized in the presence of a rubbery polymer from a mixture of monomers comprising an aromatic vinyl compound and a cyanide vinyl compound, and the copolymer (B) is copolymerized independently of the rubber graft copolymer (A) from a mixture of monomers comprising an aromatic vinyl compound and a cyanide vinyl compound, and the calcium content relative to the total mass of the thermoplastic resin composition is 0.3% by mass or less.

Description

Technical Field

[0001] This invention relates to thermoplastic resin compositions, resin molded articles, and coated articles. This application claims priority based on Japanese Patent Application No. 2024-003220 filed on January 12, 2024, the contents of which are incorporated herein by reference. Background Technology

[0002] Molded products made of ABS resin are widely used in a wide range of fields, including office equipment, information and communication equipment, electronic and electrical equipment, home appliances, automobiles, and construction, due to their excellent impact resistance, mechanical strength, and chemical resistance. Furthermore, when ABS resin is plated to form coated products, it exhibits excellent coating appearance, high adhesion strength of the coating film, and excellent thermal cycling characteristics, thus finding diverse applications in plastic coating. For example, in the automotive industry, efforts are underway to promote its application in coating radiator grille components or emblem parts.

[0003] The coating properties are easily affected by the characteristics of the resin composition forming the molded article and / or molding conditions. Therefore, even when using a resin composition containing ABS resin, poor coating appearance may occur. Under poor molding conditions, appearance defects such as peeling and blistering of the coating film may occur, significantly impairing the commercial value of the final product.

[0004] Therefore, as a thermoplastic resin composition that has high adhesion strength of the coating film and does not produce coating film swelling or cracking during thermal cycling, a thermoplastic resin composition comprising a graft copolymer with different rubber particle sizes and a specific copolymer different from the graft copolymer in a specified ratio has been proposed (Patent Document 1).

[0005] Patent documents Patent Document 1: Japanese Patent No. 6218347 Summary of the Invention The problem the invention aims to solve However, while coating the thermoplastic resin composition of Patent Document 1 can achieve good adhesion and sometimes shows some effectiveness in thermal cycling tests (also known as "thermal cycling tests," which involve repeatedly applying slow temperature changes over time), it is prone to peeling or blistering during thermal shock tests (which involve repeatedly applying drastic temperature changes over time). This can damage the decorative properties of the product or impair its function as a component.

[0006] The present invention aims to provide a thermoplastic resin composition with excellent impact resistance and / or flowability during molding, excellent coating adhesion strength, coating appearance and / or thermal cycling characteristics, and which can maintain coating adhesion in thermal shock tests, as well as resin molded articles and coated articles (decorative parts) using the composition.

[0007] means for solving problems The present invention includes the following solutions.

[0008] [1] A thermoplastic resin composition comprising a melt blend of a rubber graft copolymer (A) and a copolymer (B), wherein the rubber graft copolymer (A) is copolymerized in the presence of a rubbery polymer from a mixture of monomers comprising an aromatic vinyl compound and a cyanide vinyl compound, and the copolymer (B) is copolymerized independently of the rubber graft copolymer (A) from a mixture of monomers comprising an aromatic vinyl compound and a cyanide vinyl compound. The composition comprises a mixture of 20 to 60 parts by mass of the rubber-grafted copolymer (A) and 40 to 80 parts by mass of the copolymer (B) relative to a total of 100 parts by mass of the rubber-grafted copolymer (A) and the copolymer (B). When the molecular weight of all polymers in the copolymer (B) is determined by GPC and converted to standard polystyrene, the proportion of polymers with a molecular weight less than 50,000 is less than 20% by mass relative to the total mass of all polymers. The total content of the rubber-grafted copolymer (A) and the copolymer (B) relative to the total mass of the thermoplastic resin composition is 75% to 100% by mass. The calcium content in the thermoplastic resin composition is less than 0.30% by mass relative to the total mass of the thermoplastic resin composition.

[0009] [2] According to the thermoplastic resin composition of [1], wherein, in all polymers of the copolymer (B), the proportion of the repeating unit derived from the vinyl cyanide compound is 10% to 30% by mass of the polymer of all repeating units, which is 85% to 100% by mass relative to the total mass of the total polymers.

[0010] [3] The thermoplastic resin composition according to [1] or [2], wherein the copolymer (B) is a mixture of multiple copolymers (B), and when the weight-average molecular weight of each copolymer (B) is determined by GPC and converted to standard polystyrene, the mixing ratio of copolymers (B) with a weight-average molecular weight of 50,000 to 300,000 is 85% to 100% by mass relative to the total mass of the mixture.

[0011] [4] The thermoplastic resin composition according to any one of [1] to [3], wherein the copolymer (B) is a mixture of copolymer (BI) and copolymer (BII), wherein the copolymer (BI) is a copolymer polymerized from a monomer mixture comprising an aromatic vinyl compound and a cyanide vinyl compound, wherein the content of the cyanide vinyl compound is 10% to 30% by mass relative to the total mass of the monomer mixture, and the mass-average molecular weight of the copolymer (BI) as converted to standard polystyrene by GPC is 50,000 to 150,000; wherein the copolymer (BII) is a copolymer polymerized from a monomer mixture comprising an aromatic vinyl compound and a cyanide vinyl compound, wherein the content of the cyanide vinyl compound is 10% to 30% by mass relative to the total mass of the monomer mixture, and the mass-average molecular weight of the copolymer (BII) as converted to standard polystyrene by GPC is greater than 150,000 and less than 300,000.

[0012] [5] The thermoplastic resin composition according to any one of [1] to [4], wherein the calcium content in the thermoplastic resin composition is 0.20% by mass or less relative to the total mass of the thermoplastic resin composition.

[0013] [6] A resin molded article comprising any one of the thermoplastic resin compositions described in [1] to [5].

[0014] [7] A coated article having a coating film on at least a portion of the surface of the resin molded article described in [6].

[0015] Invention Effects This invention provides a thermoplastic resin composition that exhibits excellent impact resistance and / or flowability during molding, excellent coating adhesion strength, coating appearance, and thermal cycling characteristics, and maintains coating adhesion even during thermal shock testing. Furthermore, it provides resin molded articles and coated articles (decorative parts) using this composition. Detailed Implementation

[0016] The following definitions apply throughout this specification and the claims.

[0017] "Molded resin article" refers to an article formed by molding the thermoplastic resin composition of the present invention.

[0018] "Coated products" refers to resin molded products that have undergone a coating process, and at least a portion of the surface of the resin molded products has a coating film.

[0019] "Thermal cycling characteristics" refers to the property of a coated product to exhibit minimal changes in its coating film during periodic, repeated tests in which the temperature changes slowly over time.

[0020] "Thermal shock properties" refers to the property of a coated product to exhibit minimal changes in its coating film during periodic, repeated tests involving drastic temperature variations over time.

[0021] "(Meth)acrylic acid" is a general term for acrylic acid and methacrylic acid.

[0022] "(Meth)acrylate" is a general term for acrylates and methacrylates.

[0023] The "~" symbol, which indicates a range of values, means that the values ​​before and after it are the lower and upper limits, respectively.

[0024] Hereinafter, the thermoplastic resin composition of the present invention will be described after explaining the rubber-containing graft copolymer (A), copolymer (B) and other components that are materials of the thermoplastic resin composition of the present invention.

[0025] <Rubber-grafted copolymer (A)> A rubber-grafted copolymer (A) is a copolymer formed by grafting monomer component (a) onto a rubbery polymer.

[0026] It should be noted that in rubber-grafted copolymers (A), it is difficult to determine how the monomer component (a) is polymerized on the rubbery polymer. That is, regarding graft copolymers (A), there are cases where it is impossible to determine directly based on their structure or properties, or where determining it is extremely impractical (unable to determine / impractical). Therefore, it is more appropriate to define graft copolymers (A) as "formed by grafting monomer components onto a rubbery polymer".

[0027] (Rubber polymer) Examples of rubbery polymers constituting rubber-grafted copolymers (A) include butadiene-based rubbers such as polybutadiene, styrene-butadiene copolymers, and acrylate-butadiene copolymers; conjugated diene-based rubbers such as styrene-isoprene copolymers; acrylic-based rubbers such as polybutyl acrylate; olefin-based rubbers such as ethylene-propylene copolymers; and silicone-based rubbers such as polyorganosiloxanes. It should be noted that these rubbery polymers can be used starting from monomers. Rubbery polymers can adopt composite rubber structures and / or core / shell structures.

[0028] As a rubbery polymer, butadiene-based rubbers are preferred from the perspective of a good balance between coating characteristics (coating adhesion strength and coating appearance) and color and impact resistance.

[0029] These rubber polymers can be used alone or in combination of two or more.

[0030] The volume average particle size of the rubber polymer is preferably 200 nm to 500 nm, more preferably 250 nm to 440 nm, and even more preferably 280 nm to 380 nm. If the volume average particle size of the rubber polymer is above the lower limit mentioned above, the thermal shock properties of the coated article are further improved. If the average particle size of the rubber polymer is below the upper limit mentioned above, the coating adhesion strength of the coated article is further improved. In addition, the flowability of the thermoplastic resin composition is improved.

[0031] While there are no particular restrictions on the manufacturing method of rubber-like polymers, emulsion polymerization is preferred for ease of particle size control. Emulsion polymerization can employ known methods, and there are no particular restrictions on the catalysts, emulsifiers, etc., that can be used; various substances can be employed.

[0032] Rubber polymers can also be enlarged rubber. Furthermore, the average particle size and distribution can be adjusted through enlargement. Examples of enlargement methods include mechanical coagulation, chemical coagulation, and coagulation methods using acid-containing copolymers.

[0033] As a chemical coagulation method, one approach involves adding an acidic substance to the latex of a rubber polymer to destabilize the latex and induce coagulation. Once the target particle size is reached, an alkaline substance is added to restabilize the latex. Examples of acidic substances include acetic acid, acetic anhydride, sulfuric acid, and phosphoric acid. Examples of alkaline substances include potassium hydroxide and sodium hydroxide.

[0034] As a coagulation method employing acid-containing copolymers, examples include methods for obtaining swellable rubber latex by mixing latex of a rubbery polymer with latex of an acid-containing copolymer. Examples of acid-containing copolymer latexes include those obtained by polymerizing in water a monomeric component containing an acid-containing monomer (e.g., a carboxyl-containing monomer such as (meth)acrylic acid), an alkyl meth)acrylic acid monomer, and other monomers that can be copolymerized with these monomers as needed.

[0035] The volume average particle size of the rubber polymer can be determined using the same measuring instrument used in the examples described later.

[0036] The volume average particle size of rubber polymers can be controlled by adjusting the polymerization conditions (temperature, time, etc.) during the manufacturing of rubber polymers, as well as the types and proportions of monomers.

[0037] Such rubbery polymers can be industrially obtained as rubber latex. Furthermore, latexes containing rubbery polymers with different volume average particle sizes can also be mixed, and even in this case, the volume average particle size can be adjusted to a preferred range.

[0038] (Monomer component (a)) The monomer component (a) constituting the rubber-grafted copolymer (A) includes an aromatic vinyl compound (a1), a cyanide vinyl compound (a2), and other vinyl compounds (a3) ​​as needed.

[0039] Examples of aromatic vinyl compounds (a1) include styrene, α-methylstyrene, vinyltoluenes (e.g., p-methylstyrene), halostyrene compounds (e.g., p-bromostyrene, p-chlorostyrene), p-tert-butylstyrene, dimethylstyrene, and vinylnaphthalene. Among these, styrene and α-methylstyrene are preferred.

[0040] These aromatic vinyl compounds (a1) can be used alone or in combination of two or more.

[0041] Examples of cyanide vinyl compounds (a2) include acrylonitrile and methacrylonitrile. Acrylonitrile is preferred.

[0042] These vinyl cyanide compounds (a2) can be used alone or in combination with two or more.

[0043] Other vinyl compounds (a3) ​​may be vinyl compounds that can be copolymerized with aromatic vinyl compounds (a1) and cyanide vinyl compounds (a2). Examples of such vinyl compounds include, for instance, alkyl methacrylates such as methyl methacrylate or ethyl methacrylate; alkyl acrylates such as methyl acrylate, ethyl acrylate or butyl acrylate; maleimide compounds such as N-phenylmaleimide or N-cyclohexylmaleimide; and unsaturated carboxylic acid compounds such as (meth)acrylic acid, itaconic acid or fumaric acid.

[0044] These other vinyl compounds (a3) ​​can be used alone or in combination of two or more.

[0045] Regarding the proportions of each vinyl compound in monomer component (a), relative to the total mass of monomer component (a), the aromatic vinyl compound (a1) is preferably 60% to 80% by mass, the cyanide vinyl compound (a2) is preferably 20% to 40% by mass, and the other vinyl compounds (a3) ​​are preferably 0% to 20% by mass.

[0046] The sum of the contents of aromatic vinyl compounds (a1), cyanide vinyl compounds (a2), and other vinyl compounds (a3) ​​shall not exceed 100% of the total mass of the monomer component (a).

[0047] If the proportions of each compound are within the above range, the performance balance of the thermoplastic resin composition, the coating adhesion strength of the coated product, the thermal cycling characteristics, the thermal shock characteristics, and the impact strength is improved.

[0048] (Including the rubber content in the rubber graft copolymer (A)) The content of the rubbery polymer component in the rubber-grafted copolymer (A) relative to the total mass of the rubber-grafted copolymer (A) is preferably 30% to 70% by mass, more preferably 40% to 60% by mass. Therefore, for the monomer component (a) constituting the rubber-grafted copolymer (A), while maintaining the proportion of each vinyl compound in the monomer component (a) within the above-mentioned range, the content is preferably 30% to 70% by mass, more preferably 40% to 60% by mass, relative to the total mass of the rubber-grafted copolymer (A).

[0049] However, the sum of the contents of the rubber polymer component and the monomer component (a) shall not exceed 100% of the total mass of the rubber-grafted copolymer (A).

[0050] By keeping the content of rubber-derived polymer components in the rubber-grafted copolymer (A) within this range, the adhesion strength, thermal cycling, thermal shock, impact resistance, or flowability of the coating process are improved.

[0051] The rubber-grafted copolymer (A) is obtained by copolymerizing a mixture of monomers (a) containing aromatic vinyl compounds and cyanide vinyl compounds in the presence of a rubbery polymer.

[0052] There are no particular limitations on the polymerization method, but emulsion polymerization is preferred from the perspective of controlling the reaction to ensure its stability. Specifically, methods include: adding a monomer mixture to the latex of a rubber polymer in one step before polymerization; adding a portion of the monomer mixture to the latex of a rubber polymer first, and then adding the remainder dropwise to the polymerization system while polymerization is underway; and polymerizing while adding all the monomer mixture dropwise to the latex of a rubber polymer. These methods can be carried out in one or more stages. In the case of two or more stages, the types and / or proportions of monomers constituting the monomer mixture in each stage can be changed. The rubber-grafted copolymer (A) obtained by emulsion polymerization is usually in a latex state.

[0053] In emulsion polymerization, free radical polymerization initiators and emulsifiers are typically used.

[0054] Examples of free radical polymerization initiators include peroxide initiators, azo initiators, and redox initiators that combine oxidants and reductants. Among these, redox initiators are preferred, and hyposulfite initiators that combine ferrous sulfate, disodium ethylenediaminetetraacetate, sodium formaldehyde sulfoxylate, and hydroperoxide are particularly preferred.

[0055] There are no particular limitations on the emulsifier, but considering its excellent latex stability during free radical polymerization and its ability to improve the polymerization rate, sodium sarcosinate, potassium fatty acid, sodium fatty acid, dipotassium alkenyl succinate, or carboxylates such as rosin soap are preferred. Among these, dipotassium alkenyl succinate is preferred because it can suppress gas generation during high-temperature molding of the obtained rubber-grafted copolymer and the thermoplastic resin composition containing the copolymer. Specific examples of dipotassium alkenyl succinate include octadecyl alkenyl succinate, heptadecanyl alkenyl succinate, and hexadecyl alkenyl succinate. These emulsifiers can be used alone or in combination of two or more. During polymerization, various known chain transfer agents can be added to control the molecular weight and / or grafting rate of the obtained rubber-grafted copolymer (A).

[0056] Polymerization conditions can be, for example, 1 to 10 hours at 30°C to 95°C.

[0057] Rubber-grafted copolymers (A) are typically obtained in latex form. Methods for recovering rubber-grafted copolymers (A) from latex can include, for example, a wet method where the latex is immersed in hot water containing a coagulant to coagulate it into a slurry; and a spray drying method where the latex is sprayed into a heated atmosphere to semi-directly recover the rubber-grafted copolymer (A).

[0058] Examples of coagulants used in wet processes include inorganic acids such as sulfuric acid, hydrochloric acid, phosphoric acid, or nitric acid; and metal salts such as calcium chloride, calcium acetate, or aluminum sulfate, which can be selected depending on the emulsifier used in the polymerization. For example, when using only carboxylic acid soaps such as fatty acid soaps and / or rosin soaps as emulsifiers, one or more of the above-mentioned coagulants can be used. When using emulsifiers such as sodium alkylbenzene sulfonate, which exhibit stable emulsifying power even in acidic regions, metal salts as coagulants are suitable.

[0059] If a wet process is used, a slurry-like rubber-grafted copolymer (A) can be obtained. Methods for obtaining a dry rubber-grafted copolymer (A) from this slurry-like copolymer (A) include: firstly, dissolving residual emulsifier residue in water for washing; then dehydrating the slurry using a centrifugal dewatering machine or a press dewatering machine; and finally drying it using an airflow dryer; or simultaneously performing dewatering and drying using a press dewatering machine and / or an extruder. By such methods, a dry rubber-grafted copolymer (A) in powder or granular form can be obtained.

[0060] While there are no particular restrictions on the cleaning conditions, it is preferable to clean the rubber graft copolymer (A) after drying when the amount of emulsifier residue contained in 100% by mass is less than 2% by mass.

[0061] (Grafting rate) Grafting rate refers to the percentage of the mass (Wa) of the vinyl monomer mixture grafted onto the rubber polymer relative to the mass (Wd) of the rubber polymer ((Wa / Wd)×100), which can usually be calculated from the acetone-insoluble matter of the rubber graft copolymer (A) obtained after graft polymerization as follows.

[0062] Acetone was added to the rubber-grafted copolymer (A), and the mixture was shaken at 25°C for 2 hours to extract the acetone-soluble matter. The acetone-insoluble matter was then filtered, dried, and its mass was measured. The grafting rate was calculated using the following formula (1). It should be noted that in the following formula (1), "m" is the mass (g) of the rubber-grafted copolymer (A) before extraction, "n" is the mass (g) of the acetone-insoluble matter, and "L" is the rubber content of the rubber-grafted copolymer (A), i.e., the mass (mass%) of the rubber polymer. The rubber content of the rubber-grafted copolymer (A) can be obtained by methods such as calculation from the polymerization formulation and polymerization addition rate, or by methods derived from infrared absorption spectroscopy.

[0063] Grafting rate (%) = {(n - m × L) / (m × L)} × 100 ··· (1) The grafting rate of the rubber-grafted copolymer (A) is not particularly limited, but is preferably 30% to 120% by mass, more preferably 35% to 100% by mass, further preferably 40% to 80% by mass, particularly preferably 50% to 80% by mass, and most preferably 60% to 80% by mass. If the grafting rate of the rubber-grafted copolymer (A) is within the above range, the impact resistance of the resin molded article is further improved, and from the perspective of coating processing, the bonding strength is more easily demonstrated.

[0064] (Weight-average molecular weight and molecular weight distribution of acetone-soluble components containing rubber graft copolymer (A)) The acetone-soluble component of the rubber graft copolymer (A) is the ungrafted copolymer of the rubber graft copolymer (A), and its composition falls within the range of the proportions of the monomer component (a).

[0065] The weight-average molecular weight (Mw) of the acetone-soluble component containing the rubber graft copolymer (A) is preferably 50,000 to 500,000, more preferably 60,000 to 300,000, and even more preferably 80,000 to 150,000. Furthermore, the molecular weight distribution (Mw / Mn) is preferably 2.0 to 5.0, more preferably 2.3 to 4.0, and even more preferably 2.6 to 3.5. Because the weight-average molecular weight (Mw) and / or molecular weight distribution (Mw / Mn) are within the above ranges, the resulting thermoplastic resin composition exhibits superior flowability and / or impact resistance, and the plating adhesion strength, thermal cycling characteristics, and thermal shock characteristics of the coated finished product are improved in a balanced manner.

[0066] Here, the mass-average molecular weight (Mw), number-average molecular weight (Mn), and molecular weight distribution (Mw / Mn) of the ungrafted copolymer (acetone-soluble) can be determined using GPC-based polystyrene conversion values. Details are provided in the following examples.

[0067] It should be noted that the proportion of acetone solubles containing rubber graft copolymer (A) with a molecular weight of less than 50,000 is preferably 40% or less, more preferably 20% or less, and even more preferably 10% or less in 100% by mass of acetone solubles.

[0068] The rubber-grafted copolymer (A) can be used alone or in combination with other substances, such as those with different volume average particle sizes of rubber polymers, different monomer composition ratios or mass average molecular weights of acetone-soluble substances, and substances with different manufacturing methods.

[0069] <Copolymer (B)> The copolymer (B) is a copolymer formed by copolymerizing a mixture of monomers containing aromatic vinyl compounds and cyanide vinyl compounds in the absence of a rubbery polymer.

[0070] When the molecular weight of all polymers in the copolymer (B), which is used as a material for the thermoplastic resin composition of the present invention, is determined by GPC conversion to standard polystyrene, the proportion of polymers with a molecular weight less than 50,000 relative to the total mass of all polymers is 20% by mass or less, preferably 15% by mass or less, more preferably 10% by mass or less, and even more preferably 6.5% by mass or less. The lower limit of this proportion can be 0% by mass.

[0071] This makes its impact resistance and thermal shock properties even better within this range.

[0072] It should be noted that the proportion of copolymer (B) with a molecular weight less than 50,000 was determined using gel permeation chromatography (GPC). Elution peaks representing the molecular weight distribution of the eluted polymers were plotted based on the results of measurements using all polymers of copolymer (B) as the sample (elution curves plotted with elution volume on the vertical axis and retention time or elution volume on the horizontal axis). The proportion of polymers with a molecular weight less than 50,000 in the total polymers of the sample can be calculated from the area ratio of this molecular weight in the elution peak. Here, this molecular weight is equivalent to the mass molecular weight. It should be noted that this value is converted from a standard polystyrene with a known molecular weight.

[0073] In the copolymer (B) melt-blended as a material of the thermoplastic resin composition of the present invention, the proportion of polymers derived from repeating units of cyanide vinyl compounds is 10% to 30% by mass (out of 100% by mass of all repeating units), preferably 85% to 100% by mass relative to the total mass of all polymers. This range makes the impact resistance or thermal shock properties, etc., more excellent.

[0074] Here, the ratio of repeating units derived from vinyl cyanide compounds to all repeating units is preferably 10% to 30% by mass, more preferably 15% to 29% by mass, and even more preferably 20% to 28% by mass.

[0075] It should be noted that the proportion of repeating units derived from vinyl cyanide compounds in all repeating units reflects the content of vinyl cyanide compounds relative to the total mass of the monomer mixture during copolymerization, and is equal to this content proportion.

[0076] The copolymer (B) may further have repeating units derived from other copolymerizable compounds besides aromatic vinyl compounds and cyanide vinyl compounds, as needed. The aromatic vinyl compounds, cyanide vinyl compounds, and other copolymerizable compounds used as monomers of the copolymer (B) can be exemplified by compounds (a1), (a2), and (a3) ​​listed as preferred compounds in the above-mentioned rubber-grafted copolymer (A).

[0077] The copolymer (B) that is melt-blended as a material of the thermoplastic resin composition of the present invention is a material independent of the rubber-grafted copolymer (A), and can be a single polymerized copolymer or a mixture of multiple copolymers polymerized separately.

[0078] [Mixture of copolymer (B)] When the copolymer (B) used in the melt-blending of the thermoplastic resin composition of the present invention is a mixture of multiple copolymers (B), the mass-average molecular weight of each copolymer (B) before blending can be determined by GPC method according to standard polystyrene conversion. After this determination, the blending ratio Z of copolymers (B) with a mass-average molecular weight of 50,000 to 300,000 is preferably 85% to 100% by mass relative to the total mass of the mixture. If it is within this range, the impact resistance or thermal shock properties of the present invention can be further improved.

[0079] For example, in a mixture of 10 parts by mass of copolymer (B) with a mass-average molecular weight of 40,000 and 40 parts by mass of copolymer (B) with a mass-average molecular weight of 100,000, the above mixing ratio Z is calculated as 80% by mass (40 parts by mass / 50 parts by mass × 100%).

[0080] The mixture of copolymers (B) is preferably a mixture of a specific copolymer (BI) and copolymer (BII).

[0081] The copolymer (BI) is a copolymer formed by polymerizing a mixture of monomers comprising an aromatic vinyl compound and a cyanide vinyl compound. The cyanide vinyl compound (i.e., repeating units derived from the cyanide vinyl compound in the copolymer (BI)) comprises 10% to 30% by mass relative to the total mass of the monomer mixture, and the copolymer (BI) has a mass-average molecular weight of 50,000 to 150,000 as converted from standard polystyrene by GPC.

[0082] Of all the repeating units constituting the copolymer (BI), the content of repeating units derived from cyanide vinyl compounds is preferably 12% to 28% by mass, more preferably 15% to 26% by mass, and even more preferably 20% to 25% by mass. By falling within this range, the performance balance of the thermoplastic resin composition of the present invention is improved in terms of flowability, coating adhesion strength of the coated article, thermal cycling characteristics, and thermal shock characteristics.

[0083] The weight-average molecular weight of the copolymer (BI) is preferably 60,000 to 140,000, more preferably 70,000 to 130,000, and even more preferably 80,000 to 120,000. By keeping the weight-average molecular weight of the copolymer (BI) within this range, the flowability, coating adhesion strength, thermal cycling characteristics, thermal shock characteristics, and impact strength of the thermoplastic resin composition involved in this invention are improved in a balanced manner.

[0084] The copolymer (BII) is a copolymer formed by polymerizing a mixture of monomers comprising an aromatic vinyl compound and a cyanide vinyl compound. The cyanide vinyl compound (i.e., repeating units derived from the cyanide vinyl compound in the copolymer (BII)) comprises 10% to 30% by mass relative to the total mass of the monomer mixture, and the copolymer (BII) has a mass-average molecular weight greater than 150,000 and less than 300,000 when converted to standard polystyrene by GPC.

[0085] In all repeating units constituting the copolymer (BII), the content of the vinyl cyanide compound is preferably 20% to 30% by mass, more preferably 24% to 29.5% by mass, and even more preferably 26% to 29% by mass. By being within this range, the performance balance of the thermoplastic resin composition of the present invention is improved in terms of flowability, coating adhesion strength of the coated article, thermal cycling characteristics, thermal shock characteristics, and impact strength.

[0086] The weight-average molecular weight of the copolymer (BII) is preferably 155,000 to 290,000, more preferably 160,000 to 270,000, and even more preferably 165,000 to 250,000. By keeping the weight-average molecular weight of the copolymer (BII) within this range, the thermoplastic resin composition of the present invention achieves a balanced improvement in the flowability, coating adhesion strength, thermal cycling characteristics, thermal shock characteristics, and impact strength of the coated article.

[0087] When the copolymer (B) used as the material of the thermoplastic resin composition of the present invention is melt-blended, the copolymer (BI) and copolymer (BII) are mixed, and when the total of copolymer (BI) and copolymer (BII) is taken as 100% by mass, the mixing ratio of copolymer (BI) / polymer (BII) is preferably 95% to 40% by mass / 5% to 60% by mass, more preferably 90% to 50% by mass / 10% to 50% by mass, and even more preferably 80% to 70% by mass / 20% to 30% by mass.

[0088] By keeping the mixing ratio of copolymer (BI) to copolymer (BII) within this range, the thermal shock properties are further improved.

[0089] Various copolymers (B) (such as copolymers (BI) etc.) can be manufactured by copolymerizing aromatic vinyl compounds with cyanide vinyl compounds and other copolymerizable compounds as needed.

[0090] As a polymerization method, any known polymerization method, such as emulsion polymerization, suspension polymerization, bulk polymerization, or a combination thereof, can be applied.

[0091] When the copolymer (B) used as a material for the thermoplastic resin composition of the present invention is melt-blended, the mixing ratio of copolymer (BV) relative to the total mass of copolymer (B) is preferably 0 to 15 by mass when mixing copolymer (BI), copolymer (BII) and copolymer (BV) that do not belong to these copolymers (BI) and copolymer (BII).

[0092] When the molecular weight of all polymers in the copolymer (B), which is used as a material for the thermoplastic resin composition of the present invention, is determined by GPC conversion to standard polystyrene, its weight-average molecular weight is preferably 50,000 to 300,000, more preferably 60,000 to 280,000, further preferably 80,000 to 250,000, and most preferably 90,000 to 200,000. Alternatively, the weight-average molecular weight may also be 85,000 to 200,000, 100,000 to 150,000, or 110,000 to 150,000.

[0093] By ensuring that the mass-average molecular weight of all polymers in copolymer (B) is within this range, the coating adhesion strength, thermal cycling characteristics, and thermal shock characteristics of the coated articles of the thermoplastic resin composition of the present invention are improved in a balanced manner.

[0094] <Other Ingredients> Other components include various additives and other resins.

[0095] As additives, well-known examples include antioxidants, light stabilizers, ultraviolet absorbers, lubricants, plasticizers, stabilizers, transesterification inhibitors, hydrolysis inhibitors, release agents, antistatic agents, colorants (e.g., pigments, dyes), fillers such as carbon fiber, glass fiber, wollastonite, calcium carbonate, silica, or talc, flame retardants such as brominated and phosphorus-based flame retardants, flame retardant additives such as antimony trioxide, anti-drip agents such as fluoropolymers, antibacterial agents, mildew inhibitors, silicone oils, and coupling agents. These additives can be used individually or in combination of two or more.

[0096] Other resins include rubber-reinforced styrene resins such as HIPS resin, ABS resin, ASA resin, AES resin, or SAS resin, as well as AS resin, polystyrene resin, nylon resin, methacrylic resin, polyvinyl chloride resin, polybutylene terephthalate resin, polyethylene terephthalate resin, polyphenylene ether resin, and polycarbonate resin. Furthermore, products can also be obtained by blending two or more of these resins, or by modifying these resins with compatibilizers or functional groups.

[0097] The necessary and / or any components used in this invention can be recycled products generated during the polymerization and / or processing, molding, etc., or recycled products recovered from the market, provided that there are no quality issues.

[0098] Thermoplastic resin composition

[0099] The thermoplastic resin composition of the present invention is a melt blend containing a rubber graft copolymer (A) and a copolymer (B).

[0100] Rubber-grafted copolymers (A) are products copolymerized from a mixture of monomers containing aromatic vinyl compounds and cyanide vinyl compounds in the presence of rubbery polymers.

[0101] The copolymer (B) is a product obtained by copolymerizing a mixture of monomers containing aromatic vinyl compounds and cyanide vinyl compounds independently of the rubber-grafted copolymer (A) in the absence of rubbery polymers.

[0102] The thermoplastic resin composition of the present invention may, as needed and without impairing the effects of the present invention, further contain other components besides the rubber graft copolymer (A) and copolymer (B). When the total mass of the rubber graft copolymer (A) and copolymer (B) is set to 100 parts by mass, the content of other components is preferably 0 to 25 parts by mass, more preferably 0 to 10 parts by mass.

[0103] From the viewpoint that the thermoplastic resin composition of the present invention can fully exert the above-mentioned effects, the total content of rubber graft copolymer (A) and copolymer (B) relative to the total mass of the thermoplastic resin composition is preferably 75% to 100% by mass, more preferably 85% to 100% by mass, and even more preferably 95% to 100% by mass.

[0104] In the thermoplastic resin composition of the present invention, when the total mass of the rubber graft copolymer (A) and copolymer (B) is set to 100 parts by mass, "the content of the rubber graft copolymer (A) is 20 to 60 parts by mass and the content of the copolymer (B) is 40 to 80 parts by mass", preferably "the content of the rubber graft copolymer (A) is 25 to 55 parts by mass and the content of the copolymer (B) is 45 to 75 parts by mass", more preferably "the content of the rubber graft copolymer (A) is 30 to 50 parts by mass and the content of the copolymer (B) is 50 to 70 parts by mass".

[0105] When the contents of the rubber graft copolymer (A) and copolymer (B) are within the specified range, the bonding strength, thermal cycling, thermal shock, impact resistance, or flowability of the coating process are excellent.

[0106] The calcium content contained in the thermoplastic resin composition of the present invention is 0.30% by mass or less relative to the total mass of the composition, more preferably 0.20% by mass or less, even more preferably 0.10% by mass or less, most preferably 0.05% by mass or less, and may also be 0% by mass below the detection limit. Within this range, the coating appearance is excellent, and the thermal cycling characteristics and thermal shock characteristics are also excellent.

[0107] In the thermoplastic resin composition of the present invention, when the total mass of the rubber graft copolymer (A) and copolymer (B) is set to 100 parts by mass, the content of the rubber polymer is preferably in the range of 10 parts by mass to 30 parts by mass, more preferably 12 parts by mass to 28 parts by mass, further preferably 15 parts by mass to 25 parts by mass, and most preferably 16 parts by mass to 20 parts by mass.

[0108] Within this range, the impact resistance, flowability, adhesion strength during the plating process, thermal cycling characteristics, or thermal shock characteristics are superior.

[0109] In the rubber-grafted copolymer (A) used as a material in the thermoplastic resin composition of the present invention, components that are not grafted onto the rubber polymer (ungrafted components) may be included. These ungrafted components are not substances polymerized as independent copolymers (B) in the absence of the rubber polymer, and therefore are not considered copolymers (B). However, when the thermoplastic resin composition of the present invention is dissolved in a solvent such as THF, and this soluble mixture is used as a sample Z for determining the molecular weight by GPC, it is sometimes difficult to distinguish between the copolymers (B) and ungrafted components contained in sample Z.

[0110] Therefore, for convenience, it is preferable not to distinguish between copolymer (B) and non-grafted components contained in sample Z, but to treat all these polymers as the test objects and calculate the molecular weight by GPC method based on polystyrene.

[0111] When the molecular weight of all polymers contained in sample Z is determined by GPC conversion to standard polystyrene, the proportion of polymers with a molecular weight less than 50,000 relative to the total mass of all polymers is preferably 10% by mass or less, more preferably 8% by mass or less, further preferably 6% by mass or less, and most preferably 4.5% by mass or less.

[0112] By falling within this range, the thermoplastic resin compositions of the present invention exhibit superior impact resistance and thermal shock properties.

[0113] <Method for manufacturing thermoplastic resin composition> The thermoplastic resin composition of the present invention is manufactured by mixing and melt-kneading a rubber graft copolymer (A), a copolymer (B), and other components as needed. There are no particular limitations on the method of mixing and kneading the components of the thermoplastic resin composition; any common mixing and kneading method can be used, such as kneading using an extruder, a Banbury mixer, or a mixing roller, followed by granulation using a granulator or similar method.

[0114] The thermoplastic resin composition of the present invention becomes a resin molded article after molding.

[0115] In the thermoplastic resin composition of the present invention, since it contains a rubber-grafted copolymer (A) and a copolymer (B), and when the total mass of the rubber-grafted copolymer (A) and the copolymer (B) is set to 100 parts by mass, the content of the rubber-grafted copolymer (A) is 20 to 60 parts by mass, and the content of the copolymer (B) is 40 to 80 parts by mass, it can exhibit excellent coating adhesion strength, and the coating appearance is not easily changed in thermal cycling characteristics and further thermal shock characteristics, thereby obtaining a resin molded article with excellent impact resistance. In addition, the flowability during molding is also excellent.

[0116] Resin molded products

[0117] The resin molded articles of the present invention are composed of the thermoplastic resin composition of the present invention described above.

[0118] The resin molded article of the present invention is obtained by molding the thermoplastic resin composition of the present invention. The molding method is not limited in any way. Examples of molding methods include injection molding, extrusion molding, compression molding, insert molding, vacuum forming, or blow molding.

[0119] Coated products

[0120] The plated article of the present invention has the resin molded article of the present invention described above, and a plated film formed on at least a portion of the surface of the resin molded article.

[0121] The plated article of the present invention is obtained by applying a plating treatment to the resin molded article of the present invention.

[0122] The plating method is not limited in any way. Examples of plating methods include electroless plating, direct plating, and chromium-free plating.

[0123] The plated product of the present invention uses the resin molded product of the present invention, so the adhesion strength between the resin molded product and the plating film is excellent. In terms of thermal cycle characteristics and thermal shock characteristics, the appearance of the plating is not likely to change, and the impact resistance is also excellent.

[0124] The plated product of the present invention can be suitably applied to a variety of uses represented by OA (office automation) equipment, information and communication equipment, electronic and electrical equipment, household appliances, automobiles, and buildings.

[0125] Examples Hereinafter, synthesis examples, examples, and comparative examples are listed to illustrate the present invention more specifically. However, the present invention is not limited by any of the following examples as long as it does not exceed its gist.

[0126] It should be noted that in the following content, "parts" means "parts by mass", and "%" means "% by mass".

[0127] [Measurement and evaluation methods] <Volume average particle diameter of rubber polymer> For the latex water dilution solution of the rubber polymer used in the synthesis of the rubber graft copolymer (A), a nanoparticle size distribution analyzer (manufactured by Nikkiso Co., Ltd., "Nanotrac UPA-EX150") based on the principle of dynamic light scattering theory was used to measure the volume average particle diameter of the rubber polymer.

[0128] <Composition ratio of copolymer (B)> Regarding the composition ratio of the copolymer (B) (the ratio of repeating units derived from monomers), a gas chromatograph (manufactured by Shimadzu Corporation, "GC-2014") was used to quantify the amount of residual monomers after the reaction, and the fixed amount (the amount incorporated into the copolymer as monomer units) was calculated by reverse calculation from this value.

[0129] <Weight average molecular weight (Mw) and number average molecular weight (Mn) of copolymer (B)> A solution obtained by dissolving the copolymer (B) in tetrahydrofuran (THF) was used as the measurement sample, and a GPC device (manufactured by Tosoh Corporation, "TOSOH EcoSEC HLC-8320GPC") was used to measure the retention time or elution volume of the copolymer (B). Based on the measurement results, the weight average molecular weight and number average molecular weight of the copolymer (B) were calculated by the standard polystyrene conversion method.

[0130] The measurement conditions of GPC and the like are as follows.

[0131] [Measurement conditions]Eluent: THF, flow rate: 0.35 ml / min, injection volume: 10 μl [Set Temperature] Pump constant temperature chamber: 40℃, Column constant temperature chamber: 40℃ [Using chromatographic columns] Connect in series using TSKgel Supermultipore HZ-M / TSKgel guardcolumn SuperMPHZ-M.

[0132] [Standard Product Information] Tosoh Corporation PStQuick MP-M Part No. 0021913 Furthermore, when calculating the mass-average molecular weight in copolymer (B), the proportion of polymers with a molecular weight less than 50,000 in all polymers of copolymer (B) is calculated by analyzing the spectra and data in the GPC determination results, based on the proportion of the area of ​​polymers with a molecular weight less than 50,000 in the total area of ​​the peaks representing the elution of all polymers (elution curve with respect to mass-average molecular weight).

[0133] When the copolymer (B) compounded and melt-blended in the thermoplastic resin composition is a mixture of multiple separately synthesized copolymers (B), the solution obtained by dissolving the mixture in THF is used as the test sample, and the above-mentioned GPC apparatus is used to measure and calculate the "content of polymers with a molecular weight of less than 50,000 in all polymers of all copolymers (B) compounded in the thermoplastic resin composition".

[0134] When the copolymer (B) compounded and melt-blended in the thermoplastic resin composition is a mixture of multiple separately synthesized copolymers (B), the solution obtained by dissolving the mixture in THF is used as the test sample, and the mass-average molecular weight of all copolymers (B) compounded in the thermoplastic resin composition is calculated using the GPC apparatus described above.

[0135] <Mass-average molecular weight (Mw) and number-average molecular weight (Mn) of the acetone-soluble fraction containing rubber-grafted polymer (A)> In the method for determining the mass-average molecular weight (Mw) and number-average molecular weight (Mn) of copolymer (B), the mass-average molecular weight (Mw) and number-average molecular weight (Mn) of acetone soluble containing rubber graft polymer (A) were determined by replacing "copolymer (B)" with "acetone soluble containing rubber graft polymer (A)".

[0136] [Synthesis example of rubber graft copolymer (A)] <Synthetic Example 1: Preparation of Rubber-Containing Grafted Copolymer (A-1)> In a nitrogen-purged reactor, 125 parts of pure water, 0.5 parts of glucose, 0.5 parts of sodium pyrophosphate, 0.005 parts of ferrous sulfate, 32 parts of polybutadiene (BR) latex with a volume average particle size of 300 nm (converted by solids content), and 8 parts of polybutadiene (BR) latex with a volume average particle size of 600 nm (converted by solids content) (the volume average particle size of the mixed BR is 360 nm) were added while stirring, and the temperature inside the reactor was raised to 65°C. The point at which the internal temperature reached 65°C was taken as the polymerization starting point. 43.2 parts of styrene (ST), 16.8 parts of acrylonitrile (AN), and 0.2 parts of a mixture of these and the chain transfer agent tert-dodecyl mercaptan were continuously added over 5 hours. Simultaneously, in parallel, an aqueous solution containing cumene hydroperoxide (0.2 parts) and sodium disproportionated rosinate (0.4 parts) as polymerization initiators was continuously added over 7 hours to complete the reaction. To the obtained latex, 1 part of 2,2'-methylenebis(4-methyl-6-tert-butylphenol) was added relative to 100 parts of the latex solids. Subsequently, relative to the latex (100 parts of polymers), 2 parts of coagulant were used to coagulate it with 5% sulfuric acid. After washing, filtering and drying, a powdered rubber-grafted copolymer (A-1) was obtained.

[0137] In this rubber-grafted copolymer (A-1), the rubber content is 40.1% and the grafting rate is 62%. Furthermore, regarding the acetone-soluble components, the cyanide vinyl monomer content is 27.2%, the weight-average molecular weight (Mw) is 122,000, and the molecular weight distribution (Mw / Mn) is 2.9.

[0138] <Synthetic Example 2: Preparation of Rubber-Containing Grafted Copolymer (A-2)> In a nitrogen-purged reactor, 125 parts of pure water, 0.5 parts of glucose, 0.5 parts of sodium pyrophosphate, 0.005 parts of ferrous sulfate, and 50 parts of polybutadiene (BR) latex with a volume average particle size of 300 nm (converted by solids content) were added. The reactor temperature was raised to 65°C while stirring. The point at which the internal temperature reached 65°C was taken as the polymerization starting point. A mixture of 36 parts of styrene (ST), 14 parts of acrylonitrile (AN), and chain transfer agents (0.12 parts of terpinene and 0.13 parts of α-methylstyrene dimer) was continuously added over 5 hours. Simultaneously, an aqueous solution containing 0.2 parts of cumene hydroperoxide and 0.4 parts of disproportionated rosinate (as polymerization initiators) was continuously added over 7 hours to complete the reaction. 1 part of 2,2'-methylenebis(4-methyl-6-tert-butylphenol) was added to the obtained latex relative to 100 parts of the latex solids. Then, relative to the latex (100 parts of polymers), 5% sulfuric acid was used to coagulate it. After washing, filtering and drying, a powdered rubber-grafted copolymer (A-2) was obtained.

[0139] In this rubber-grafted copolymer (A-2), the rubber content is 49.8% and the grafting rate is 60%. Furthermore, regarding the acetone-soluble components, the cyanide vinyl monomer content is 27.2%, the weight-average molecular weight (Mw) is 280,000, and the molecular weight distribution (Mw / Mn) is 4.9.

[0140] <Synthetic Example 3: Preparation of Rubber-Containing Grafted Copolymer (A-3)> In a nitrogen-purged reactor, 125 parts of pure water, 0.5 parts of glucose, 0.5 parts of sodium pyrophosphate, 0.005 parts of ferrous sulfate, and 40 parts of polybutadiene (BR) latex with a volume average particle size of 200 nm (converted by solids content) were added. The reactor temperature was raised to 65°C while stirring. The point at which the internal temperature reached 65°C was taken as the polymerization starting point. Styrene (ST), acrylonitrile (AN), and a mixture of these with a chain transfer agent (tert-dodecyl mercaptan) (0.22 parts) were continuously added over 5 hours. Simultaneously, an aqueous solution containing cumene hydroperoxide (0.2 parts) and disproportionated rosinate (0.4 parts) as polymerization initiators was continuously added over 7 hours to complete the reaction. Add 1 part of 2,2'-methylenebis(4-methyl-6-tert-butylphenol) to the obtained latex relative to 100 parts of the latex solids component. Then, coagulate the latex with 5% sulfuric acid at a ratio of 2 parts of coagulant relative to 100 parts of the latex (polymer component). After washing, filtering and drying, a powdered rubber-grafted copolymer (A-3) is obtained.

[0141] In this rubber-grafted copolymer (A-3), the rubber content is 40.2% and the grafting rate is 80%. Furthermore, regarding the acetone-soluble components, the cyanide vinyl monomer content is 27.2%, the weight-average molecular weight (Mw) is 90,000, and the molecular weight distribution (Mw / Mn) is 2.5.

[0142] <Synthetic Example 4: Preparation of Rubber-Containing Grafted Copolymer (A-4)> In a nitrogen-purged reactor, 125 parts of pure water, 0.5 parts of glucose, 0.5 parts of sodium pyrophosphate, 0.005 parts of ferrous sulfate, and 65 parts of polybutadiene (BR) latex with a volume average particle size of 300 nm (converted to solids content) were added. The reactor temperature was raised to 65°C while stirring. The point at which the internal temperature reached 65°C was taken as the polymerization starting point. Styrene (ST), acrylonitrile (AN), and a mixture of these with a chain transfer agent (tert-dodecyl mercaptan) (0.19 parts) were continuously added over 5 hours. Simultaneously, an aqueous solution containing cumene hydroperoxide (0.18 parts) and sodium disproportionated rosinate (0.4 parts) as polymerization initiators was continuously added over 7 hours to complete the reaction. 1 part of 2,2'-methylenebis(4-methyl-6-tert-butylphenol) was added to the obtained latex relative to 100 parts of the latex solids. Then, relative to the latex (100 parts of polymers), 2 parts of coagulant were used to coagulate it with 5% sulfuric acid. After washing, filtering and drying, a powdered rubber-grafted copolymer (A-4) was obtained.

[0143] In this rubber-grafted copolymer (A-4), the rubber content is 64.9% and the grafting rate is 39%. Furthermore, regarding the acetone-soluble components, the cyanide vinyl monomer content is 27.2%, the weight-average molecular weight (Mw) is 115,000, and the molecular weight distribution (Mw / Mn) is 3.9.

[0144] [Example of synthesis of copolymer (B)] <Synthetic Example 5: Copolymer (BI-1)> After purging a stainless steel autoclave equipped with a ribbon-type agitator with nitrogen, 76.5 parts by weight of styrene, 23.5 parts by weight of acrylonitrile, and 20 parts by weight of toluene were continuously added to the reaction vessel. A solution of 0.26 parts by weight of tert-dodecyl mercaptan and 5 parts by weight of toluene, used as a molecular weight regulator, and a solution of 0.1 parts by weight of 1,1'-azobis(cyclohexane-1-nitrile) and 5 parts by weight of toluene, used as a polymerization initiator, was continuously supplied. Polymerization was carried out at 110°C. After the polymerization conversion reached 75%, the unreacted monomers and solvent were directly devolatilized from the resulting copolymer solution using a 2-shaft 3-stage extruder with venting holes, thereby obtaining the copolymer (BI-1). The obtained copolymer had a mass-average molecular weight of 95,000 and a cyanide vinyl compound content of 23.5%.

[0145] <Synthetic Example 6: Copolymer (BI-2)> Except for changing the amount of tert-dodecyl mercaptan, which is used as a molecular weight regulator, to 0.47 parts by mass, the same procedure as in Synthesis Example 5 was followed to obtain copolymer (BI-2). The obtained copolymer had a mass-average molecular weight of 55,000 and a content of cyanide vinyl compound of 23.5%.

[0146] <Synthesis Example 7: Copolymer (BI-3)> Except for using 86.0 parts by weight of styrene and 14.0 parts by weight of acrylonitrile, and changing the tert-dodecyl mercaptan used as a molecular weight regulator to 0.50 parts by weight, the copolymer (BI-3) was obtained by operating in the same manner as in Synthesis Example 5. The copolymer had a mass-average molecular weight of 40,000 and a content of 14.0% of vinyl cyanide compound.

[0147] <Synthetic Example 8: Copolymer (BI-4)> Except for changing the amount of tert-dodecyl mercaptan, which is used as a molecular weight regulator, to 0.36 parts by mass, the same procedure as in Synthesis Example 7 was followed to obtain copolymer (BI-4). The obtained copolymer had a mass-average molecular weight of 75,000 and a content of cyanide vinyl compound of 14.0%.

[0148] <Synthetic Example 9: Copolymer (BI-5)> Except for using 81.0 parts by mass of styrene and 19.0 parts by mass of acrylonitrile, and changing the tert-dodecyl mercaptan used as a molecular weight regulator to 0.20 parts by mass, the copolymer (BI-6) was obtained by operating in the same manner as in Synthesis Example 5. The copolymer had a mass-average molecular weight of 120,000 and a content of 19.0% of vinyl cyanide compound.

[0149] <Synthetic Example 10: Copolymer (BI-6)> A mixture of 125 parts water, 0.5 parts calcium phosphate (TCP), 0.003 parts potassium alkenyl succinate, 0.05 parts 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, 0.04 parts 1,1-di(tert-hexylperoxy)cyclohexane, 0.04 parts tert-butylperoxy-2-ethylhexyl carbonate, 0.38 parts tert-dodecyl mercaptan, and a monomer mixture consisting of 76.5 parts styrene and 23.5 parts acrylonitrile was added to a reactor. The reaction was initiated at 65°C, heated for 6.5 hours, and then brought to 125°C for further reaction. After reacting at 125°C for 1 hour, a copolymer slurry was obtained. Upon cooling, the slurry was washed with 200 parts water and simultaneously centrifuged to obtain the copolymer (BI-6). The obtained copolymer had a mass-average molecular weight of 95,000 and a cyanide vinyl compound content of 23.5%. It should be noted that the residual amount of Ca from TCP is 0.05%.

[0150] <Synthetic Example 11: Copolymer (BI-7)> Except for changing the amount of calcium phosphate (TCP) to 0.8 parts, the same procedure as in Synthesis Example 10 was followed to obtain a copolymer slurry. After cooling, the slurry was washed with 100 parts of water and simultaneously centrifuged to obtain copolymer (BI-7). The polymer composition of the obtained copolymer was the same as that of copolymer (BI-6), with a residual Ca content derived from TCP of 0.3%.

[0151] <Synthetic Example 12: Copolymer (BI-8)> The same procedure as in Synthesis Example 11 was followed to obtain a copolymer slurry. After cooling, the slurry was washed with 45 parts of water and centrifuged to obtain copolymer (BI-8). The polymer composition of the obtained copolymer was the same as that of copolymer (BI-8), with a residual Ca content derived from TCP of 0.6%.

[0152] <Synthetic Example 13: Copolymer (BII-1)> After purging a stainless steel autoclave equipped with a ribbon-type agitator with nitrogen, 72.5 parts by weight of styrene, 27.5 parts by weight of acrylonitrile, and 20 parts by weight of toluene were continuously added to the reaction vessel. A solution of 0.19 parts by weight of tert-dodecyl mercaptan and 5 parts by weight of toluene, used as a molecular weight regulator, and a solution of 0.1 parts by weight of 1,1'-azobis(cyclohexane-1-nitrile) and 5 parts by weight of toluene, used as a polymerization initiator, was continuously supplied. Polymerization was carried out at 110°C. After the polymerization conversion reached 75%, the unreacted monomers and solvent were directly devolatilized from the resulting copolymer solution using a 2-shaft 3-stage extruder with venting holes, thereby obtaining the copolymer (BII-1). The obtained copolymer had a mass-average molecular weight of 185,000 and a cyanide vinyl compound content of 27.5%.

[0153] <Synthetic Example 14: Copolymer (BII-2)> Except for using 81.0 parts by mass of styrene and 19.0 parts by mass of acrylonitrile, and changing the tert-dodecyl mercaptan used as a molecular weight regulator to 0.20 parts by mass, the copolymer (BII-2) was obtained by operating in the same manner as in Synthesis Example 13. The copolymer had a mass-average molecular weight of 175,000 and a content of 19.0% of vinyl cyanide compound.

[0154] <Synthetic Example 15: Copolymer (BII-3)> Except for using 65.0 parts by weight of styrene and 35.0 parts by weight of acrylonitrile, and changing the tert-dodecyl mercaptan used as a molecular weight regulator to 0.18 parts by weight, the copolymer (BII-3) was obtained by operating in the same manner as in Synthesis Example 13. The copolymer had a mass-average molecular weight of 185,000 and a content of 35.0% of vinyl cyanide compound.

[0155] <Synthetic Example 16: Copolymer (BII-4)> A mixture of 125 parts water, 0.5 parts calcium phosphate (TCP), 0.003 parts potassium alkenyl succinate, 0.05 parts 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, 0.04 parts 1,1-di(tert-hexylperoxy)cyclohexane, 0.04 parts tert-butylperoxy-2-ethylhexyl carbonate, 0.18 parts tert-dodecyl mercaptan, and a monomer mixture consisting of 73.5 parts styrene and 27.5 parts acrylonitrile was added to a reactor. The reaction was initiated at 65°C, heated for 6.5 hours, and then brought to 125°C for further reaction. After reacting at 125°C for 1 hour, a copolymer slurry was obtained. Upon cooling, the slurry was washed with 200 parts water and simultaneously centrifuged to obtain the copolymer (BII-4). The obtained copolymer had a mass-average molecular weight of 185,000 and a vinyl cyanide content of 27.5%. It should be noted that the residual amount of Ca from TCP is 0.05%.

[0156] <Examples 1-13, Comparative Examples 1-4> (Preparation of thermoplastic resin compositions) A thermoplastic resin composition was prepared by mixing 0.5 parts of rubber graft copolymer (A), copolymer (BI) and (BII) and "KaoWax EB-G (trade name)" (ethylene bis-stearamide) manufactured by Kao Corporation in the proportions shown in Table 1 and then melt-blending the mixture.

[0157] Using a 30mm twin-screw extruder ("TEX30α" manufactured by Nippon Steel Corporation), the mixture of materials was melt-blended and granulated at a temperature of 200°C to obtain granules of the thermoplastic resin composition.

[0158] The following evaluations were conducted on the thermoplastic resin compositions of each example. The results are shown in Table 1.

[0159] <Calcium (Ca) content> The thermoplastic resin composition was burned in an electric furnace to ash it, and the Ca content was calculated using a fluorescence X-ray measuring device (HITACHI High-TechScience model: EA6000VX).

[0160] <Proportion of polymers with a molecular weight less than 50,000 in the thermoplastic resin composition> A solution of the soluble substance obtained by dissolving a thermoplastic resin composition in tetrahydrofuran (THF) was used as the test sample. The retention time or elution volume of the eluted polymer was measured using a GPC apparatus (Tosoh Corporation, "TOSOH EcoSEC HLC-8320GPC") under the same test conditions as for copolymer (B). Based on the test results, the molecular weight of the eluted polymer was calculated using the standard polystyrene conversion method. The proportion of polymers with a molecular weight less than 50,000 in all eluted polymers was calculated through data analysis (slice data) from the GPC test results. This proportion is the percentage of the total area of ​​the elution peaks (elution curve related to mass-average molecular weight) representing the polymer elution, where polymers with a molecular weight less than 50,000 occupy the area.

[0161] <Proportion of copolymers (B) with a mass average molecular weight of 50,000 to 300,000 among the separately polymerized copolymers (B) in the thermoplastic resin composition> As shown in Table 1, any of the separately polymerized (BI) and (BII) copolymers were combined and incorporated into the thermoplastic resin composition. The proportion of copolymer (B) with a mass-average molecular weight of 50,000 to 300,000 relative to the total mass of all incorporated copolymers (B) was calculated.

[0162] <The proportion of polymers derived from cyanide vinyl compounds in all copolymers (B) formulated in the thermoplastic resin composition, where the repeating unit is 10% to 30% by mass> For each (BI) and (BII) coordinating as copolymer (B), calculations were performed based on the monomer composition coordinating during polymerization. In all embodiments, the coordinating copolymer (B) consisted entirely of a polymer derived from a repeating unit of a vinyl cyanide compound, comprising 10% to 30% by mass of 100% by mass of all repeating units. That is, the proportion of the polymer described above was 100% by mass in all embodiments.

[0163] (Evaluation of coating adhesion strength) Test pieces were obtained by injection molding granules of thermoplastic resin composition using an 80-ton injection molding machine (J80ADS-110U manufactured by Nippon Steel Corporation). The injection molding was performed using a mold (90mm long × 50mm wide × 3mm thick) for evaluating the adhesion strength, under the conditions of a barrel temperature of 250°C, a mold temperature of 60°C, and a medium injection speed (15mm / sec).

[0164] The obtained test pieces were coated, and the coating film was peeled off vertically on a load tester and its strength was measured. The coating adhesion strength was determined according to the following standards.

[0165] ◎: The coating adhesion strength is above 12N / cm, which is excellent; 〇: The coating adhesion strength is above 10N / cm and less than 12N / cm, which poses no problem in actual use; △: The coating adhesion strength is above 8N / cm and less than 10N / cm. It can be used if the application is restricted. ×: The coating adhesion strength is less than 8N / cm, and it cannot be used.

[0166] In evaluating the adhesion strength of the plating, the plating process is carried out according to the following steps (1) to (15).

[0167] (1) Degreasing process [5 minutes at 50°C] (2) Washing with water (3) Etching treatment: CrO3: 400g / l, sulfuric acid: 200cc / l [at 65℃ for 15 minutes] (4) Washing with water (5) Acid treatment [at 23°C for 1 minute] (6) Washing with water (7) Catalytic treatment [3 minutes at 30°C] (8) Washing with water (9) Activation treatment [3 minutes at 40°C] (10) Wash with water (11) Electroless Ni plating [at 40°C for 5 minutes] (12) Wash with water (13) Copper electroplating [film thickness: 35 μm, 60 minutes at 20°C] (14) Wash with water (15) Drying [at 80°C for 2 hours] (Evaluation of thermal cycling characteristics) Test pieces were obtained by injection molding granules of a thermoplastic resin composition using an 80-ton injection molding machine (J80ADS-110U manufactured by Nippon Steel Corporation). The injection molding was performed using a mold (100mm long × 100mm wide × 3mm thick) for thermal cycling evaluation, under conditions of barrel temperature 230°C, mold temperature 60°C, and injection speed 50mm / sec.

[0168] The obtained test pieces underwent a coating process, and a thermal cycling test apparatus (model EC-86MTPE, manufactured by Hitachi Global Living Solutions Co., Ltd.) was used. The temperature was lowered from 23°C to -30°C for 30 minutes, held at -30°C for 1 hour, then raised to 23°C for 30 minutes, held at 23°C for 15 minutes, then raised to 80°C for 30 minutes, held at 80°C for 1 hour, and finally lowered back to 23°C for 30 minutes, held at 23°C for 15 minutes. This constituted one cycle, and 20 cycles were performed. Afterwards, the coating condition of the product was visually observed, and the thermal cycling characteristics were determined according to the following criteria.

[0169] ◎: The coating remains unchanged, which is excellent.

[0170] ○: There are some bubbles in the coating, but there are no problems in actual use.

[0171] △: The coating may blister or other changes. It can be used if the application is limited.

[0172] ×: The coating exhibits significant variations such as blistering, and has not reached a practical level.

[0173] In the evaluation of thermal cycling characteristics, the plating process is carried out according to the following steps (1) to (17).

[0174] (1) Degreasing process [5 minutes at 50°C] (2) Washing with water (3) Etching treatment: CrO3: 400g / l, sulfuric acid: 200cc / l [at 65℃ for 20 minutes] (4) Washing with water (5) Acid treatment [at 23°C for 1 minute] (6) Washing with water (7) Catalytic treatment [3 minutes at 30°C] (8) Washing with water (9) Activation treatment [3 minutes at 40°C] (10) Wash with water (11) Electroless Ni plating [at 40°C for 5 minutes] (12) Wash with water (13) Electroplating copper [film thickness: 20 μm, 20 minutes at 20°C] (14) Wash with water (15) Electroplating Ni [film thickness: 10 μm, 55°C for 15 minutes] (16) Wash with water (17) Electroplating of Cr [film thickness: 0.3 μm, 2 minutes at 45°C] (Evaluation of thermal shock properties) Using the same coated products as those evaluated for thermal cycling characteristics, a Hitachi Global Living Solutions Co., Ltd. model ES-306L thermal shock testing apparatus was used. The samples were held in a bath cooled to -30°C for 1 hour, then heated to 80°C within 10 minutes, held at 80°C for 1 hour, cooled to -30°C within 10 minutes, held at -30°C for 1 hour, and then heated to 80°C again, held at 80°C for 1 hour. This was repeated as one cycle. After the 20th cycle of holding at 80°C for 1 hour, the samples were allowed to cool, removed, and the state of the coating was visually observed to determine the thermal shock characteristics.

[0175] ◎: The coating remains unchanged, which is excellent.

[0176] ○: There are some bubbles in the coating, but there are no problems in actual use.

[0177] △: The coating may blister or other changes. It can be used if the application is limited.

[0178] ×: The coating exhibits significant variations such as blistering, and has not reached a practical level.

[0179] (Evaluation of Charpy impact strength) A 100-ton injection molding machine (FANUC ROBOSHOT α-S100iB, FANUC Corporation) was used to injection mold granules of a thermoplastic resin composition, resulting in test pieces (80 mm long, 10 mm wide, and 4 mm thick). Injection molding was performed at a molding temperature of 235°C and a mold temperature of 60°C.

[0180] For the obtained test pieces, the Charpy impact strength (with notch) was determined at a test temperature of 23°C according to ISO 179, and the impact resistance was determined according to the following standards.

[0181] ◎: Charpy impact strength is 20 kJ / m 2 The above is excellent.

[0182] ○: Charpy impact strength is 15 kJ / m 2 Above and below 20 kJ / m 2 There are no problems in actual use.

[0183] △: Charpy impact strength is less than 15 kJ / m 2 It has not reached a practical level.

[0184] (Evaluation of liquidity (spiral flow)) Using a spiral flow mold (15mm wide × 2mm thick), granules of a thermoplastic resin composition were injection molded using an 85-ton injection molding machine (J85AD-110H, Nippon Steel Corporation) under conditions of barrel temperature 270°C, mold temperature 60°C, and injection pressure 100MPa. The spiral flow length (mm) of the resulting molded article was measured, and the flowability (spiral flow) was determined according to the following criteria.

[0185] ◎: The spiral flow length is over 470mm, and the material is excellent.

[0186] 〇: The spiral flow length is more than 450mm and less than 470mm, which is not a problem in actual use.

[0187] △: The spiral flow length is 430mm or more and less than 450mm. It can be used if the application is limited.

[0188] ×: The spiral flow length is less than 430mm, which does not meet the practical requirements.

[0189] (Molded appearance) Visual observation was performed on the entire surface of the test piece (90mm long × 50mm wide × 3mm thick) before plating, which was formed to determine the adhesion strength of the plating.

[0190] ○: There are 0 to 2 foreign objects, and the appearance is excellent.

[0191] △: There are 3 to 4 foreign objects, and their appearance is worse than "〇".

[0192] ×: There are more than 5 foreign objects, and the appearance is extremely poor compared to “〇”.

[0193] (Platinum coating appearance) The entire surface of the plated test piece (90mm long × 50mm wide × 3mm thick), which was formed to determine the adhesion strength of the plating, was visually observed.

[0194] ○: There are 0 to 2 foreign objects, and the appearance is excellent.

[0195] △: There are 3 to 4 foreign objects, and their appearance is worse than "〇".

[0196] ×: There are more than 5 foreign objects, and the appearance is extremely poor compared to “〇”.

[0197] [Table 1A]

[0198] [Table 1B]

[0199] [Table 1C]

[0200] [Table 1D]

[0201] It can be seen that the thermoplastic resin compositions of Examples 1 to 13 can provide resin molded articles with excellent coating adhesion strength, thermal cycling characteristics, thermal shock characteristics, impact resistance, flowability, molding appearance and coating appearance.

[0202] The coating appearance of Example 11 was inferior to that of the other examples. This is believed to be due to a slightly higher amount of Ca in the thermoplastic resin composition.

[0203] The thermal shock properties of Example 12 were worse than those of the other examples. This is believed to be because the copolymer (B) does not contain (BII).

[0204] The coating adhesion strength and thermal cycling characteristics of Example 13 were worse than those of the other examples. This is believed to be because the quality average molecular weight of copolymer (B) was slightly lower and it did not contain (BII).

[0205] The thermoplastic resin composition of Comparative Example 1 has poor thermal cycling characteristics, thermal shock characteristics, molding appearance, and coating appearance due to its high Ca content.

[0206] For the thermoplastic resin compositions of Comparative Examples 2 to 4, since the proportion of polymers with a molecular weight of less than 50,000 is high in all copolymers (B) therein, the impact resistance and / or coating adhesion strength are poor, and the thermal cycling characteristics and thermal shock characteristics are also poor.

[0207] Industrial availability According to the present invention, a thermoplastic resin composition is provided that yields resin molded articles with excellent adhesion strength, thermal cycling characteristics, thermal shock characteristics, impact resistance, flowability, and appearance in the plating process, as well as resin molded articles and plating processed articles obtained by molding the thermoplastic resin composition. Therefore, the present invention is of great industrial importance.

Claims

1. A thermoplastic resin composition comprising a melt blend of a rubber graft copolymer (A) and a copolymer (B), The rubber-grafted copolymer (A) is copolymerized from a mixture of monomers containing aromatic vinyl compounds and cyanide vinyl compounds in the presence of a rubbery polymer. The copolymer (B) is a copolymer of monomers comprising aromatic vinyl compounds and cyanide vinyl compounds, independent of the rubber-grafted copolymer (A). in, The copolymers are mixed in a ratio of 20 to 60 parts by weight of the rubber-grafted copolymer (A) and 40 to 80 parts by weight of the copolymer (B) relative to a total of 100 parts by weight of the rubber-grafted copolymer (A) and the copolymer (B). When the molecular weight of all polymers in copolymer (B) is determined by GPC and converted to standard polystyrene, the proportion of polymers with a molecular weight less than 50,000 is less than 20% by mass relative to the total mass of all polymers. The total content of the rubber-grafted copolymer (A) and the copolymer (B) relative to the total mass of the thermoplastic resin composition is 75% to 100% by mass. The calcium content in the thermoplastic resin composition is less than 0.30% by mass relative to the total mass of the thermoplastic resin composition.

2. The thermoplastic resin composition according to claim 1, wherein, In all polymers of the copolymer (B), the proportion of repeating units derived from vinyl cyanide compounds is 10% to 30% by mass of all repeating units, which is 85% to 100% by mass relative to the total mass of all polymers.

3. The thermoplastic resin composition according to claim 2, wherein, The copolymer (B) is a mixture of multiple copolymers (B). When the mass-average molecular weight of each copolymer (B) is determined by GPC and converted to standard polystyrene, the mixing ratio of copolymers (B) with a mass-average molecular weight of 50,000 to 300,000 is 85% to 100% by mass relative to the total mass of the mixture.

4. The thermoplastic resin composition according to claim 1, wherein, The copolymer (B) is a mixture of copolymer (BI) and copolymer (BII). The copolymer (BI) is a copolymer polymerized from a monomer mixture containing an aromatic vinyl compound and a cyanide vinyl compound. The cyanide vinyl compound content is 10% to 30% by mass relative to the total mass of the monomer mixture. The mass-average molecular weight of the copolymer (BI) converted to standard polystyrene by GPC is 50,000 to 150,000. The copolymer (BII) is a copolymer polymerized from a monomer mixture containing an aromatic vinyl compound and a cyanide vinyl compound, wherein the cyanide vinyl compound content is 10% to 30% by mass relative to the total mass of the monomer mixture, and the weight-average molecular weight of the copolymer (BII) converted to standard polystyrene by GPC is greater than 150,000 and less than 300,000.

5. The thermoplastic resin composition according to claim 1, wherein, The calcium content in the thermoplastic resin composition is less than 0.20% by mass relative to the total mass of the thermoplastic resin composition.

6. A resin molded article comprising the thermoplastic resin composition according to any one of claims 1 to 5.

7. A plated article having a plated film on at least a portion of the surface of the resin molded article of claim 6.

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