Resin composition, pellets, molded article, and method for inhibiting discoloration

Abstract

A resin composition comprising, relative to 100 parts by mass of a thermoplastic resin, 0.001 to 10.0 parts by mass of a stabilizer, 0.1 to 10.0 parts by mass of a silver-containing antibacterial agent, and 0.1 to 30 parts by mass of a halogen compound.

Description

[Technical field]

[0001] The present invention relates to a resin composition, a pellet, a molded article, and a method for inhibiting discoloration, and in particular to a resin composition containing a thermoplastic polyester resin as a main component. [Background technology]

[0002] Thermoplastic polyester resins have excellent mechanical strength, electrical properties, and other physical and chemical properties, and are therefore used as engineering plastics in a wide range of applications, including automobiles, electrical and electronic devices, and sanitary fields such as toilet seats and bathroom accessories. In recent years, there has been a problem with the products used in these applications, such as the generation of bacteria that can have a negative effect on the human body. In addition, there are an increasing number of cases in which antibacterial properties are imparted to add value to products. One method of imparting antibacterial properties to thermoplastic polyester resins is to knead in a commercially available antibacterial agent, but depending on the type of antibacterial agent, sufficient antibacterial properties may not be expressed. For this reason, thermoplastic polyester resin compositions with excellent antibacterial properties are being studied. Specifically, Patent Document 1 describes a method for producing a thermoplastic polyester resin, comprising: (A) a thermoplastic polyester resin; (B) an alkali metal salt, an alkaline earth metal salt, or an ammonium salt of zirconium phosphate, the ratio of which is phosphate ions and zirconium ions being 3 / 2, carrying silver ions and hydrogen ions; and (C) baking the resulting mixture at 500 to 1300°C to produce an antibacterial agent having a content of 0.1 to 5% by weight (based on the total composition) represented by general formula (I). Ag a A b H c Zr 2 (PO 4 ) 3 nH 2 O (I) (In the formula, A is at least one ion selected from an alkali metal ion, an alkaline earth metal ion, and an ammonium ion; q is the valence of A; a and c are positive numbers; b is 0 or a positive number; and q, a, b, and c are numbers that satisfy a+qb+c=1. Also, n is a number that satisfies 0≦n≦6.) (C) 1 to 30% by weight (based on the total composition) of a halogenated aromatic bisimide compound represented by general formula (II) [ka] (In the formula, R 1 represents a divalent organic acid group, and R 2 and R 3 represents a divalent organic group having one or more halogen atoms X. n=1 to 4, n'=0 to 4) is disclosed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2002-348444 A Summary of the Invention [Problem to be solved by the invention]

[0004] As described above, antibacterial properties can be imparted to a thermoplastic polyester resin by blending an antibacterial agent containing silver into the thermoplastic polyester resin. On the other hand, in order to impart thermal stability to thermoplastic polyester resins, it is common to blend a stabilizer therein. Here, the present inventors have conducted research and found that when a stabilizer is added to a thermoplastic polyester resin containing such an antibacterial agent, the degree of discoloration of the resulting resin composition increases. The present invention aims to solve these problems, and to provide a resin composition having an excellent balance of antibacterial properties, thermal stability, and color stability, as well as pellets, a molded product, and a method for inhibiting discoloration. [Means for solving the problem]

[0005] In light of the above-mentioned problems, the present inventors have conducted research and found that the above-mentioned problems can be solved by blending a halogen compound in addition to a thermoplastic resin, a stabilizer, and an antibacterial agent containing silver. Specifically, the above problems were solved by the following means. [1] For 100 parts by mass of thermoplastic resin, 0.001 to 10.0 parts by mass of a stabilizer; 0.1 to 10.0 parts by mass of an antibacterial agent containing silver; and 0.1 to 30 parts by mass of a halogen compound. Resin composition. [2] The resin composition according to [1], wherein the mass ratio of the halogen atoms contained in the resin composition to the stabilizer, that is, halogen atoms / stabilizer, is 1.0 or more. [3] The thermoplastic resin includes a thermoplastic polyester resin. The resin composition according to [1] or [2]. [4] The thermoplastic polyester resin includes a polybutylene terephthalate resin. The resin composition according to [3]. [5] The resin composition according to any one of [1] to [4], wherein the stabilizer comprises one or more compounds selected from the group consisting of thioether compounds, hindered phenol compounds, and phosphite compounds. [6] The resin composition according to any one of [1] to [5], wherein the stabilizer comprises a thioether compound. [7] The resin composition according to any one of [1] to [6], wherein the silver-containing antibacterial agent includes an inorganic silver-based antibacterial agent. [8] The resin composition according to any one of [1] to [7], wherein the silver-containing antibacterial agent includes a glass-based antibacterial agent. [9] The resin composition according to any one of [1] to [8], wherein the halogen compound contains a bromine atom and / or a fluorine atom.

[10] The resin composition according to any one of [1] to [9], wherein the halogen compound contains a fluorine atom.

[11] The resin composition according to any one of [1] to

[10] , wherein the halogen compound contains a bromine atom.

[12] The resin composition according to

[11] , wherein the halogen compound has a free bromine content of 0.5 mass% or more.

[13] A thermoplastic polyester resin having an intrinsic viscosity of 1.0 dL / g or more. Antibacterial agents containing silver Titanium oxide, A resin composition for use in sanitary parts.

[14] The mass ratio of the halogen atoms contained in the resin composition to the stabilizer, that is, halogen atoms / stabilizer, is 1.0 or more; the thermoplastic resin comprises a polybutylene terephthalate resin, the stabilizer comprises one or more compounds selected from the group consisting of hindered phenol compounds and phosphite compounds; the silver-containing antibacterial agent comprises a glass-based antibacterial agent; The halogen compound contains a bromine atom and / or a fluorine atom. The resin composition according to [1].

[15] Pellets of the resin composition according to any one of [1] to

[14] .

[16] A molded article formed from the resin composition according to any one of [1] to

[14] .

[17] A molded article formed from the pellets according to

[15] .

[18] The molded article according to

[16] or

[17] , which is a part for sanitary use.

[19] A method for inhibiting discoloration of a resin composition containing 0.001 to 10.0 parts by mass of a stabilizer and 0.1 to 10.0 parts by mass of an antibacterial agent containing silver per 100 parts by mass of a thermoplastic resin, the method comprising blending 0.1 to 30 parts by mass of a halogen compound per 100 parts by mass of the thermoplastic resin.

[20] A method for inhibiting discoloration of a resin composition containing 0.01 to 1.0 part by mass of a stabilizer and 0.1 to 3.0 parts by mass of an antibacterial agent containing silver per 100 parts by mass of a thermoplastic polyester resin, the method comprising blending 0.1 to 30 parts by mass of a halogen compound per 100 parts by mass of the thermoplastic polyester resin. Effect of the Invention

[0006] The present invention makes it possible to provide a resin composition having an excellent balance of antibacterial properties, thermal stability, and color stability, as well as pellets, a molded article, and a method for inhibiting discoloration. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] Hereinafter, an embodiment of the present invention (hereinafter, simply referred to as "the present embodiment") will be described in detail. Note that the present embodiment is an example for explaining the present invention, and the present invention is not limited to the present embodiment. In this specification, the use of "to" means that the numerical values ​​before and after it are included as the lower limit and upper limit. In this specification, various physical properties and characteristic values ​​are those at 23° C. unless otherwise specified. In this specification, unless otherwise specified, the weight average molecular weight and number average molecular weight are polystyrene-equivalent values ​​measured by GPC (gel permeation chromatography) using a Tosoh HLC-8320GPC EcoSEC with tetrahydrofuran as a solvent and Shodex KF-G, KF-805L x 3, KF-800D columns at a column temperature of 40°C and a flow rate of 1.2 mL / min, and detected at a detection wavelength of 254 nm. If the measurement methods, etc. described in the standards shown in this specification vary from year to year, they will be based on the standards as of January 1, 2023, unless otherwise stated.

[0008] The resin composition of the present embodiment is characterized by containing 0.001 to 10.0 parts by mass of a stabilizer, 0.1 to 10.0 parts by mass of a silver-containing antibacterial agent, and 0.1 to 30 parts by mass of a halogen compound, relative to 100 parts by mass of a thermoplastic resin. By using such a constitution, a resin composition having a good balance of antibacterial properties, thermal stability, and color stability can be obtained. It was speculated that silver, being highly reactive, would react with sulfur, phosphorus, etc. contained in the stabilizer, causing discoloration of the resin composition. In the present embodiment, it was speculated that by blending a halogen compound, the halogen would coordinate around the silver, suppressing the action of the silver and the stabilizer. Furthermore, by using a prescribed amount of a halogen-based flame retardant as the halogen compound, it is possible to enhance the flame retardancy while maintaining high levels of antibacterial properties, thermal stability, and color stability of the resin composition.

[0009] <Thermoplastic resin> The resin composition of the present embodiment contains a thermoplastic resin. Examples of the thermoplastic resin used in the present embodiment include polyester resin (thermoplastic polyester resin), polyamide resin, polycarbonate resin, polystyrene resin, polyethylene resin, polypropylene resin, polyolefin resin such as cyclic cycloolefin resin, polyacetal resin, polyimide resin, polyetherimide resin, polyurethane resin, polyphenylene ether resin, polyphenylene sulfide resin, polysulfone resin, polymethacrylate resin, and the like, and the thermoplastic resin polyester resin is preferred. The resin composition of the present embodiment may contain only one type of thermoplastic resin, or may contain two or more types of thermoplastic resin.

[0010] The resin composition of the present embodiment may be an alloy in which two or more types of thermoplastic resins are blended. For example, polybutylene terephthalate resin and polycarbonate resin, polybutylene terephthalate resin and polyethylene terephthalate resin, and polybutylene terephthalate resin and polystyrene resin may be blended.

[0011] <<Thermoplastic polyester resin>> The thermoplastic polyester resin is not particularly limited in terms of its type, but preferably contains a polyalkylene terephthalate resin, preferably contains a polyethylene terephthalate resin and / or a polybutylene terephthalate resin, and more preferably contains a polybutylene terephthalate resin.

[0012] The polyalkylene terephthalate resin is a polyester obtained by, for example, polycondensation of terephthalic acid as a dicarboxylic acid compound and a diol, and may be either a homopolyester or a copolyester.

[0013] As the dicarboxylic acid compound constituting the polyalkylene terephthalate resin, a terphthalic acid compound or an ester-forming derivative thereof is preferably used. Aromatic dicarboxylic acids other than terephthalic acid can also be used in combination. Examples of such dicarboxylic acids include isophthalic acid, orthophthalic acid, 1,5-naphthalenedicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, biphenyl-2,2'-dicarboxylic acid, biphenyl-3,3'-dicarboxylic acid, biphenyl-4,4'-dicarboxylic acid, diphenylether-4,4'-dicarboxylic acid, diphenylmethane-4,4'-dicarboxylic acid, diphenylsulfone-4,4'-dicarboxylic acid, diphenylisopropylidene-4,4'-dicarboxylic acid, 1,2-bis(phenoxy)ethane-4,4'-dicarboxylic acid, anthracene-2,5-dicarboxylic acid, anthracene-2,6-dicarboxylic acid, p-terphenylene-4,4'-dicarboxylic acid, and pyridine-2,5-dicarboxylic acid. These can be used in the polycondensation reaction as ester-forming derivatives such as dimethyl esters in addition to free acids. Of the above, isophthalic acid or its ester-forming derivatives are particularly preferred.

[0014] In addition, one or more aliphatic dicarboxylic acids such as adipic acid, azelaic acid, dodecanedioic acid, and sebacic acid, and alicyclic dicarboxylic acids such as 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, and 1,4-cyclohexanedicarboxylic acid can be mixed and used in small amounts together with terephthalic acid and the above-mentioned aromatic dicarboxylic acids.

[0015] Examples of dihydroxy compounds constituting the polyalkylene terephthalate resin include aliphatic diols such as ethylene glycol, propylene glycol, 1,4-butanediol, hexylene glycol, neopentyl glycol, 2-methylpropane-1,3-diol, diethylene glycol, and triethylene glycol, alicyclic diols such as cyclohexane-1,4-dimethanol, and mixtures thereof. Among these, 1,4-butanediol and ethylene glycol are particularly preferred.

[0016] In addition, one or more long-chain diols having a molecular weight of 400 to 6,000, such as polyethylene glycol, poly-1,3-propylene glycol, polytetramethylene glycol, etc. may be copolymerized. In addition, aromatic diols such as hydroquinone, resorcinol, naphthalene diol, dihydroxydiphenyl ether, and 2,2-bis(4-hydroxyphenyl)propane may also be used.

[0017] In addition to the above-mentioned bifunctional monomers, a small amount of a trifunctional monomer such as trimellitic acid, trimesic acid, pyromellitic acid, pentaerythritol, or trimethylolpropane may be used in combination to introduce a branched structure, or a monofunctional compound such as a fatty acid may be used in combination to adjust the molecular weight.

[0018] The polyalkylene terephthalate resin is preferably one that is mainly composed of polycondensation of terephthalic acid and diol, i.e., one that is composed of this polycondensate in an amount of more than 50% by mass of the entire resin, preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, still more preferably 95% by mass or more, and even more preferably 99% by mass or more. The diol is preferably an aliphatic diol, more preferably 1,4-butanediol or ethylene glycol, and more preferably 1,4-butanediol.

[0019] The amount of terminal carboxyl groups of the thermoplastic polyester resin (preferably polybutylene terephthalate resin) may be appropriately selected and determined, but is usually 60 eq / ton or less, preferably 50 eq / ton or less, and more preferably 30 eq / ton or less. By making it 60 eq / ton or less, the generation of gas during melt molding of the resin composition tends to be more effectively suppressed. The lower limit of the amount of terminal carboxyl groups is not particularly set, but is usually 3 eq / ton or more, preferably 5 eq / ton or more, and more preferably 10 eq / ton or more.

[0020] The amount of terminal carboxyl groups in the thermoplastic polyester resin is a value measured by dissolving 0.5 g of the resin in 25 mL of benzyl alcohol and titrating it with a 0.01 mol / L benzyl alcohol solution of sodium hydroxide. The amount of terminal carboxyl groups can be adjusted by any conventional method, such as adjusting the polymerization conditions such as the raw material charge ratio during polymerization, the polymerization temperature, and the pressure reduction method, or by reacting a terminal blocking agent.

[0021] The intrinsic viscosity of the thermoplastic polyester resin (preferably polybutylene terephthalate resin) is preferably 0.60 dL / g or more, more preferably 0.70 dL / g or more, even more preferably 0.80 dL / g or more, even more preferably 0.90 dL / g or more, and even more preferably 1.00 dL / g or more. By making it equal to or more than the lower limit, there is a tendency that the deterioration of physical properties such as strength can be effectively suppressed. In addition, the intrinsic viscosity of the thermoplastic polyester resin (preferably polybutylene terephthalate resin) is preferably 2.0 dL / g or less, more preferably 1.8 dL / g or less, even more preferably 1.5 dL / g or less, even more preferably 1.3 dL / g or less, and even more preferably 1.2 dL / g or less. By making it equal to or less than the upper limit, there is a tendency that the deterioration of fluidity can be effectively suppressed.

[0022] The intrinsic viscosity is measured by the following method. Thermoplastic polyester resin pellets are dissolved in a mixed solvent of phenol / 1,1,2,2-tetrachloroethane (1 / 1 by mass) by stirring at 110°C for 1 hour to a concentration of 1.00 g / dL. The solution is then cooled to 30°C. Using a fully automatic solution viscometer, the number of seconds it takes for the sample solution and the solvent alone to fall at 30°C are measured, and the intrinsic viscosity is calculated using the formula: Intrinsic viscosity=((1+4K H η sp ) 0.5 -1) / (2K H C) Here, η sp = η / η 0 -1, η is the time it takes for the sample solution to fall, η 0 is the time it takes for the solvent to fall, C is the concentration of the sample solution (g / dL), and K H is Huggins' constant. K H was set to 0.33. The fully automatic solution viscometer used is a product of Shibayama Scientific Co., Ltd. When the resin composition of the present embodiment contains two or more thermoplastic polyester resins, the intrinsic viscosity is the intrinsic viscosity of the mixture.

[0023] The catalyst used in carrying out the esterification reaction may be a conventionally known catalyst, and examples thereof include titanium compounds, tin compounds, magnesium compounds, calcium compounds, etc. Among these, titanium compounds are particularly preferred. Specific examples of titanium compounds as esterification catalysts include titanium alcoholates such as tetramethyl titanate, tetraisopropyl titanate, and tetrabutyl titanate, and titanium phenolates such as tetraphenyl titanate.

[0024] The polybutylene terephthalate resin may be a polybutylene terephthalate resin modified by copolymerization (hereinafter, also referred to as a "modified polybutylene terephthalate resin"), and specific preferred copolymers include polyester ether resins copolymerized with polyalkylene glycols (particularly polytetramethylene glycol), dimer acid copolymerized polybutylene terephthalate resins, and isophthalic acid copolymerized polybutylene terephthalate resins.

[0025] When a polyester ether resin copolymerized with polytetramethylene glycol is used as the modified polybutylene terephthalate resin, the proportion of the tetramethylene glycol component in the copolymer is preferably 3 to 40 mass%, more preferably 5 to 30 mass%, and even more preferably 10 to 25 mass%. When a dimer acid copolymerized polybutylene terephthalate resin is used as the modified polybutylene terephthalate resin, the proportion of the dimer acid component in the total carboxylic acid components is preferably 0.5 to 30 mol %, more preferably 1 to 20 mol %, and even more preferably 3 to 15 mol %, in terms of carboxylic acid groups. When an isophthalic acid copolymerized polybutylene terephthalate resin is used as the modified polybutylene terephthalate resin, the proportion of isophthalic acid components in all carboxylic acid components is preferably 1 to 30 mol %, more preferably 1 to 20 mol %, and even more preferably 3 to 15 mol %, in terms of carboxylic acid groups. Among the modified polybutylene terephthalate resins, polyester ether resins copolymerized with polytetramethylene glycol and isophthalic acid copolymerized polybutylene terephthalate resins are preferred.

[0026] <<Styrene-based resin>> Examples of polystyrene resins include homopolymers of styrene monomers, copolymers of styrene monomers and monomers copolymerizable with styrene monomers, etc. In the copolymers of styrene monomers and monomers copolymerizable with styrene monomers, it is preferable that 50% by mass or more of the total monomers are styrene monomers, more preferably 60% by mass or more of the total monomers are styrene monomers, and it is also preferable that 100% by mass or less of the total monomers are styrene monomers.

[0027] The styrene-based monomer means styrene and styrene having a substituent, and examples thereof include styrene, α-methylstyrene, p-methylstyrene, vinylxylene, ethylstyrene, dimethylstyrene, p-tert-butylstyrene, vinylnaphthalene, methoxystyrene, monobromostyrene, dibromostyrene, fluorostyrene, tribromostyrene, and the like. Styrene and α-methylstyrene are more preferable, and styrene is particularly preferable. Furthermore, among the monomers constituting the styrene-based resin, examples of monomers other than the styrene-based monomers include (meth)acrylic acid ester-based monomers, maleimide-based monomers such as maleimide, N-methylmaleimide, and N-phenylmaleimide, α,β-unsaturated carboxylic acids and their anhydrides such as acrylic acid, methacrylic acid, maleic acid, maleic anhydride, phthalic acid, and itaconic acid, and rubbers such as butadiene.

[0028] The polystyrene resin used in this embodiment may contain a rubber-reinforced polystyrene resin. Specific examples of the rubber-reinforced polystyrene resin include acrylonitrile-styrene copolymer (AS resin), high impact polystyrene resin (HIPS), acrylonitrile-butadiene-styrene copolymer (ABS resin), acrylonitrile-acrylic rubber-styrene copolymer (AAS resin), acrylonitrile-styrene-acrylic rubber copolymer (ASA resin), acrylonitrile-ethylene propylene rubber-styrene copolymer (AES resin), and styrene-IPN type rubber copolymer.

[0029] It is also preferable that the polystyrene-based resin used in this embodiment is partly a styrene-maleic acid polymer (preferably a styrene-maleic anhydride polymer). The styrene-maleic acid polymer acts as a compatibilizer between the polyester resin and the polystyrene resin and / or the rubber-reinforced polystyrene resin. As a result, the strength of the resulting molded product can be increased.

[0030] In this embodiment, the polystyrene resin preferably includes at least one selected from polystyrene resin (GPPS), acrylonitrile-styrene copolymer (AS resin), high impact polystyrene resin (HIPS), acrylonitrile-butadiene-styrene copolymer (ABS resin), acrylonitrile-acrylic rubber-styrene copolymer (AAS resin), acrylonitrile-styrene-acrylic rubber copolymer (ASA resin), and acrylonitrile-ethylene propylene rubber-styrene copolymer (AES resin), and more preferably includes high impact polystyrene resin (HIPS). Also, from the viewpoint of heat resistance, polystyrene resin (GPPS) and acrylonitrile-styrene copolymer (AS resin) are more preferable. The styrene-based resin used in the present embodiment may be either a virgin styrene-based resin or a recycled amorphous styrene-based resin.

[0031] <<Polycarbonate resin>> Polycarbonate resins are thermoplastic polymers or copolymers, which may be branched, obtained by reacting a dihydroxy compound or a small amount of a polyhydroxy compound with phosgene or a carbonic acid diester.

[0032] The dihydroxy compound as the raw material is one that does not substantially contain bromine atoms, and is preferably an aromatic dihydroxy compound.Specific examples include 2,2-bis(4-hydroxyphenyl)propane (i.e., bisphenol A), tetramethylbisphenol A, bis(4-hydroxyphenyl)-p-diisopropylbenzene, hydroquinone, resorcinol, 4,4-dihydroxydiphenyl, and the like, and preferably bisphenol A.Also, a compound in which one or more tetraalkylphosphonium sulfonates are bonded to the above aromatic dihydroxy compound can be used.

[0033] As the polycarbonate resin, among the above, aromatic polycarbonate resin derived from 2,2-bis(4-hydroxyphenyl)propane, or aromatic polycarbonate copolymer derived from 2,2-bis(4-hydroxyphenyl)propane and other aromatic dihydroxy compounds is preferable. Also, it may be a copolymer mainly composed of aromatic polycarbonate resin, such as a copolymer with a polymer or oligomer having a siloxane structure. Furthermore, two or more of the above polycarbonate resins may be mixed and used.

[0034] In order to adjust the molecular weight of the polycarbonate resin, a monovalent aromatic hydroxy compound may be used, such as m- and p-methylphenol, m- and p-propylphenol, p-tert-butylphenol, and p-long-chain alkyl-substituted phenol.

[0035] The viscosity average molecular weight (Mv) of the polycarbonate resin is preferably 10,000 or more, more preferably 12,000 or more, even more preferably 13,000 or more, and particularly preferably more than 14,000. If a viscosity average molecular weight lower than 10,000 is used, the resulting resin composition tends to have low mechanical strength such as impact resistance. In addition, Mv is preferably 60,000 or less, more preferably 40,000 or less, even more preferably 35,000 or less, and even more preferably 30,000 or less, and may be 25,000 or less, or 20,000 or less. If it is higher than 60,000, the flowability of the resin composition may be poor, and moldability may be deteriorated.

[0036] In the present invention, the viscosity average molecular weight (Mv) of a polycarbonate resin is a value calculated from the intrinsic viscosity ([η]) obtained by measuring the viscosity of a methylene chloride solution of the polycarbonate resin at 25° C. using an Ubbelohde viscometer, and then calculating the viscosity from the following Schnell viscosity formula: [η]=1.23×10 -4 Mv 0.83

[0037] The melt flow rate (MFR) of the polycarbonate resin measured in accordance with JIS K7210 (temperature 300°C, load 1.20 kgf) is preferably 3 to 100 g / 10 min, more preferably 6 to 70 g / 10 min. When the MFR is within the above range, the effects of the present invention tend to be more effectively exhibited. The melt volume rate (MVR) of polycarbonate resin, measured according to JIS K7210 (temperature 300°C, load 1.20kgf), is 0.5 to 20cm. 3 g / 10 min., and 1 to 10 cm 3 When the MVR is within the above range, the effects of the present invention tend to be more effectively exhibited.

[0038] The method for producing the polycarbonate resin is not particularly limited, and polycarbonate resins produced by either the phosgene method (interfacial polymerization method) or the melting method (ester exchange method) can be used. In addition, polycarbonate resins produced by the melting method and then subjected to post-treatment to adjust the amount of OH groups at the terminals are also preferred.

[0039] The polycarbonate resin used in this embodiment may be either a virgin polycarbonate resin or a recycled polycarbonate resin.

[0040] An example of a blend form of the thermoplastic resin in this embodiment is a thermoplastic polyester resin (preferably a polyalkylene terephthalate resin, more preferably a polybutylene terephthalate resin) that accounts for 70 mass% or more, preferably 80 mass% or more, 85 mass% or more, 90 mass% or more, or 95 mass% or more of the thermoplastic resin contained in the resin composition.

[0041] In one example of the blend form of the thermoplastic resin in this embodiment, 70% by mass or more, preferably 80% by mass or more, 85% by mass or more, 90% by mass or more, or 95% by mass or more of the thermoplastic resin contained in the resin composition is a thermoplastic polyester resin (preferably a polybutylene terephthalate resin) and a polystyrene resin and / or a polycarbonate resin. In this embodiment, the thermoplastic polyester resin in the thermoplastic resin contained in the resin composition is preferably 50% by mass or more, more preferably 55% by mass or more, and is preferably 80% by mass or less, more preferably 75% by mass or less.

[0042] The content of the thermoplastic resin in the resin composition of this embodiment is preferably 70 mass% or more, more preferably 75 mass% or more, and even more preferably 80 mass% or more, based on 100 mass% of the resin composition. Depending on the application, etc., it may be 85 mass% or more, 90 mass% or more, or 95 mass% or more, or it is preferably 99 mass% or less, and may be 95 mass% or less, or 90 mass% or less, depending on the application, etc. The resin composition of the present embodiment may contain only one type of thermoplastic resin, or may contain two or more types. When two or more types are contained, the total amount is preferably in the above range.

[0043] <Stabilizer> The resin composition of the present embodiment preferably contains a stabilizer. By containing the stabilizer, a resin composition and a molded article having excellent thermal stability can be obtained. The stabilizer preferably contains one or more compounds selected from the group consisting of a thioether compound, a hindered phenol compound, and a phosphite compound, more preferably contains one or more compounds selected from the group consisting of a hindered phenol compound and a phosphite compound, and further preferably contains a thioether compound. In this embodiment, it is also preferable to use two or more of the thioether-based compound, the hindered phenol-based compound, and the phosphite-based compound in combination as necessary. By using two or more stabilizers in combination in this way, the thermal stability is further improved and tends to continue for a long period of time.

[0044] As the thioether-based compound, any conventionally known sulfur atom-containing compound can be used, and among them, thioethers are preferred. By including the thioether-based compound in the resin composition of the present embodiment, the appearance of the molded product tends to be improved and the thermal stability tends to be improved. Specific examples include didodecylthiodipropionate, ditetradecylthiodipropionate, dioctadecylthiodipropionate, pentaerythritol tetrakis(3-dodecylthiopropionate), 2,2-bis{[3-(dodecylthio)-1-oxopropoxy]methyl}propane-1,3-diylbis[3-(dodecylthio)propionate], thiobis(N-phenyl-β-naphthylamine), 2-mercaptobenzothiazole, 2-mercaptobenzimidazole, tetramethylthiuram monosulfide, tetramethylthiuram disulfide, nickel dibutyldithiocarbamate, nickel isopropylxanthate, and trilauryltrithiophosphite. Among these, 2,2-bis{[3-(dodecylthio)-1-oxopropoxy]methyl}propane-1,3-diylbis[3-(dodecylthio)propionate] is preferable. Commercially available products include "Seenox 412S" manufactured by Shipro Chemical Co., Ltd. and "Adekastab AO-412S" manufactured by ADEKA Corporation.

[0045] Examples of hindered phenol compounds include pentaerythritol tetrakis (3-(3,5-di-t-butyl-4-hydroxyphenyl) propionate), octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, thiodiethylene bis (3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate), pentaerythritol tetrakis (3-(3,5-di-neopentyl-4-hydroxyphenyl) propionate), 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene, etc. Among these, pentaerythritol tetrakis (3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate) and octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate are preferred. Commercially available products include those manufactured by ADEKA Corporation under the trade names "ADEKA STAB AO-60" and "ADEKA STAB AO-330."

[0046] The phosphite compound is preferably a compound represented by the formula: R 2 OP(OR 3 )(OR 4 ) (In the formula, R 2 , R 3 and R 4 are each a hydrogen atom, an alkyl group having 1 to 30 carbon atoms, or an aryl group having 6 to 30 carbon atoms, and R 2 , R 3 and R 4 At least one of the groups is an aryl group having 6 to 30 carbon atoms.) Examples of the compound include compounds represented by the following formula: Examples of the phosphite compound include triphenyl phosphite, tris(nonylphenyl)phosphite, dilauryl hydrogen phosphite, triethyl phosphite, tridecyl phosphite, tris(2-ethylhexyl)phosphite, tris(tridecyl)phosphite, tristearyl phosphite, diphenyl monodecyl phosphite, monophenyl didecyl phosphite, diphenyl mono(tridecyl)phosphite, tetraphenyl dipropylene glycol diphosphite, tetraphenyl tetra(tridecyl)pentaerythritol tetraphosphite, hydrogenated bisphenol A phenol phosphite polymer, diphenyl hydrogen phosphite, 4,4'-butylidene-bis(3-methyl-6-tert-butylphenyl di(tridecyl)phosphite), tetra(tridecyl) 4,4'-isopropyl phosphite, tetra(tridecyl) ... propylidenediphenyl diphosphite, bis(tridecyl)pentaerythritol diphosphite, bis(nonylphenyl)pentaerythritol diphosphite, dilauryl pentaerythritol diphosphite, distearyl pentaerythritol diphosphite, tris(4-tert-butylphenyl)phosphite, tris(2,4-di-tert-butylphenyl)phosphite, hydrogenated bisphenol A pentaerythritol phosphite polymer, bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite, bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphite, 2,2'-methylenebis(4,6-di-tert-butylphenyl)octyl phosphite, bis(2,4-dicumylphenyl)pentaerythritol diphosphite, and the like. Among these, bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphite is preferable. An example of a commercially available product is "ADEKA STAB PEP-36" manufactured by ADEKA Corporation.

[0047] Other examples of stabilizers include the following: JP 2021-063196 A, paragraphs 0067 to 0075; JP 2018-070722 A, paragraphs 0046 to 0057; JP 2019-056035 A, paragraphs 0030 to 0037; and WO 2017 / 038949 A, paragraphs 0066 to 0078. The contents of these are incorporated herein by reference.

[0048] The content of the stabilizer in the resin composition of the present embodiment is 0.001 parts by mass or more, preferably 0.01 parts by mass or more, more preferably 0.03 parts by mass or more, even more preferably 0.05 parts by mass or more, and even more preferably 0.1 parts by mass or more, relative to 100 parts by mass of the thermoplastic polyester resin. By making it equal to or more than the lower limit, the effect of suppressing thermal deterioration and oxidative deterioration of the resin during melt kneading, molding, and use as a molded product tends to be improved, and heat resistance tends to be improved. In addition, the upper limit of the content of the stabilizer is 10.0 parts by mass or less, preferably 1.0 parts by mass or less, more preferably 0.8 parts by mass or less, more preferably 0.6 parts by mass or less, even more preferably 0.5 parts by mass or less, even more preferably 0.4 parts by mass or less, even more preferably 0.3 parts by mass or less, and even more preferably 0.24 parts by mass or less, relative to the total 100 parts by mass of the thermoplastic polyester resin. By setting the content to be equal to or less than the upper limit, adverse effects on appearance and physical properties due to aggregation of additives such as stabilizers tend to be effectively suppressed, and discoloration of the resin composition tends to be suppressed. The resin composition of the present embodiment may contain only one type of stabilizer, or may contain two or more types. When two or more types are contained, the total amount is preferably in the above range.

[0049] The resin composition of the present embodiment may also be configured to be substantially free of a stabilizer. Substantially free of a stabilizer means, for example, that the content of the stabilizer is less than 0.001 part by mass, or may be less than 0.0001 part by mass, or may be 0 part by mass, relative to 100 parts by mass of the thermoplastic resin. If a stabilizer is not added, discoloration occurs due to retention of the resin composition, but this can be compensated for by adding a colorant. For example, by adding titanium oxide to achieve whiteness, a composition that does not substantially contain a stabilizer can be obtained.

[0050] <Antibacterial agent containing silver> The resin composition of the present embodiment contains an antibacterial agent containing silver. By containing the antibacterial agent, a resin composition or a molded article having excellent antibacterial properties can be obtained. The silver-containing antibacterial agent in this embodiment is preferably an inorganic antibacterial agent (inorganic silver-based antibacterial agent) that usually elutes silver ions. More specifically, the silver-containing antibacterial agent in this embodiment is preferably one in which silver (preferably silver ions) is supported on zeolite, glass, phosphoric acid compounds, etc., and the antibacterial effect is expressed by releasing silver (preferably silver ions). The silver-containing antibacterial agent may carry a metal other than silver in addition to silver (preferably silver ions). Examples of the metal other than silver include copper (preferably copper ions) and zinc (preferably zinc ions). The silver-containing antibacterial agent in this embodiment preferably includes a glass-based antibacterial agent.

[0051] It is also preferable that the silver-containing antibacterial agent used in this embodiment is substantially free of zeolite. Substantially free means that the content of zeolite is less than 10 parts by mass, preferably 1 part by mass or less, more preferably 0.1 part by mass or less, and even more preferably 0.01 part by mass or less, when the total amount of the silver-containing antibacterial agent is 100 parts by mass.

[0052] The glass-based antibacterial agent may be a soluble glass that supports silver (preferably silver ions) so that the silver (preferably silver ions) can be eluted. Examples of the soluble glass include P 2 O 5 -RO-R 2 O-based glass or B 2 O 3 -SiO 2 -R2 O-based glass (RO is an oxide of alkaline earth metals such as CaO and MgO, 2 O is Li 2 O, Na 2 OK 2 O and other alkali metal oxides.

[0053] The average particle size of the silver-containing antibacterial agent in this embodiment is preferably 20 μm or less, more preferably 15 μm or less, and may be 1.5 μm or less, or may be 0.01 μm or more. The average particle size means the diameter when converted into a sphere having the same volume as the silver-containing antibacterial agent, and this value is the number average particle size.

[0054] The antibacterial agent containing silver may be blended in the resin composition as a masterbatch. When the antibacterial agent containing silver is made into a masterbatch, the resin used for the masterbatch is preferably a thermoplastic polyester resin, more preferably a polyethylene terephthalate resin and / or a polybutylene terephthalate resin. The concentration of the antibacterial agent containing silver when made into a masterbatch is preferably 1 to 50 mass%, more preferably 5 to 30 mass%. In particular, when the resin composition of the present embodiment contains a flame retardant, it is preferable to also prepare a master batch of the antibacterial agent containing silver. By adopting such a configuration, the productivity of the resin composition (for example, pellets) tends to be further improved.

[0055] Commercially available products include "Bactekiller" manufactured by Fuji Chemical Co., Ltd. (BM-102NS (SB), BM-103CL, BM-103CK, BM-103NA, FK-68, etc.), "Million Guard" manufactured by Koa Glass Co., Ltd., and "Novaron" manufactured by Toagosei Co., Ltd.

[0056] The content of the antibacterial agent containing silver in the resin composition of this embodiment is 0.1 parts by mass or more, preferably 0.2 parts by mass or more, more preferably 0.3 parts by mass or more, and even more preferably 0.4 parts by mass or more, relative to 100 parts by mass of the total thermoplastic polyester resin. By making it equal to or more than the lower limit, the antibacterial property of the obtained molded article tends to be further improved. In addition, the upper limit of the content of the antibacterial agent containing silver is 10.0 parts by mass or less, preferably 3.0 parts by mass or less, more preferably 2.5 parts by mass or less, more preferably 2.0 parts by mass or less, even more preferably 1.5 parts by mass or less, even more preferably 1.0 parts by mass or less, even more preferably 0.9 parts by mass or less, and even more preferably 0.6 parts by mass or less, relative to 100 parts by mass of the total thermoplastic polyester resin. By making it equal to or less than the upper limit, the color tone change of the obtained molded article tends to be more effectively suppressed. In addition, when the antibacterial agent containing silver is made into a master batch, the amount of the resin used in the master batch is not included in the above content. The resin composition of the present embodiment may contain only one type of silver-containing antibacterial agent, or may contain two or more types. When two or more types are contained, the total amount is preferably in the above range.

[0057] <Halogen compounds> The resin composition of the present embodiment contains a halogen compound. By containing a halogen compound, a resin composition or a molded article having excellent color stability can be obtained. The halogen compound used in the present embodiment preferably contains at least one selected from the group consisting of a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, more preferably contains at least one selected from the group consisting of a fluorine atom, a chlorine atom, and a bromine atom, and further preferably contains a bromine atom and / or a fluorine atom. An example of the halogen compound in this embodiment is one that contains fluorine atoms, and more preferably contains polytetrafluoroethylene. When a compound containing a fluorine atom is used as the halogen compound, the type is not particularly limited, but examples thereof include homopolymers or copolymers of fluorine-containing monomers such as tetrafluoroethylene, chlorotrifluoroethylene, vinylidene fluoride, hexafluoropropylene, and perfluoroalkyl vinyl ether.Specific examples include homopolymers such as polytetrafluoroethylene, polychlorotrifluoroethylene, and polyvinylidene fluoride, and copolymers such as tetrafluoroethylene-hexafluoropropylene copolymers, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymers, ethylene-tetrafluoroethylene copolymers, and ethylene-chlorotrifluoroethylene copolymers. Another example of the halogen compound in this embodiment is one that contains a bromine atom, and more preferably contains a bromine-based flame retardant.

[0058] When a brominated flame retardant is used as the halogen compound, the type is not particularly limited, but brominated phthalimide, brominated poly(meth)acrylate, brominated polycarbonate, brominated epoxy, and brominated polystyrene are preferred, brominated phthalimide, brominated poly(meth)acrylate, brominated polycarbonate, and brominated epoxy are more preferred, brominated poly(meth)acrylate, brominated polycarbonate, and brominated epoxy are even more preferred, and brominated poly(meth)acrylate is even more preferred. In particular, brominated poly(meth)acrylates are more easily mixed with antimony compounds and can achieve better flame retardancy.

[0059] The bromine-based flame retardant preferably has a free bromine content of 0.5% by mass or more. By setting the content in this range, discoloration of the resin composition can be further suppressed. In addition, the free bromine content is preferably 2.0% by mass or less. By setting the content in this range, mold corrosion resistance during molding tends to be further improved.

[0060] The brominated phthalimide is preferably one represented by the formula (1). [ka] (In formula (1), D is an alkylene group, an arylene group, -S(=O) 2 It represents a group consisting of a combination of two or more of -, -C(=O)-, and -O-. i is an integer of 1 to 4.

[0061] In formula (1), D is an alkylene group, an arylene group, -S(=O) 2 represents a group consisting of a combination of two or more of -, -C(=O)-, and -O-, and is an alkylene group or an arylene group and -S(=O) 2 A group consisting of a combination of at least one of -, -C(=O)-, and -O- is preferred, and an alkylene group or an arylene group and -S(=O) 2 A group consisting of a combination of one of -, -C(=O)-, and -O- is more preferred, and an alkylene group is even more preferred. The group consisting of a combination of an alkylene group and -O- is intended to include, for example, a combination of two alkylene groups and one -O- (the same applies to other combinations). The alkylene group represented by D is preferably an alkylene group having 1 to 6 carbon atoms, more preferably a methylene group, an ethylene group, a propylene group, or a butylene group. The arylene group is preferably a phenylene group. "i" is an integer of 1 to 4, and is preferably 4.

[0062] Examples of the brominated phthalimide represented by formula (1) include N,N'-(bistetrabromophthalimide)ethane, N,N'-(bistetrabromophthalimide)propane, N,N'-(bistetrabromophthalimide)butane, N,N'-(bistetrabromophthalimide)diethyl ether, N,N'-(bistetrabromophthalimide)dipropyl ether, N,N'-(bistetrabromophthalimide)dibutyl ether, N,N'-(bistetrabromophthalimide)diphenyl sulfone, N,N'-(bistetrabromophthalimide)diphenyl ketone, and N,N'-(bistetrabromophthalimide)diphenyl ether.

[0063] The brominated phthalimide represented by formula (1) is preferably a brominated phthalimide represented by formula (2). [ka] (In formula (2), i is an integer of 1 to 4.) "i" is an integer of 1 to 4, and is preferably 4.

[0064] The brominated poly(meth)acrylate is preferably a polymer obtained by polymerizing a bromine atom-containing benzyl (meth)acrylate alone, copolymerizing two or more kinds of the bromine atom-containing benzyl (meth)acrylate, or copolymerizing the bromine atom with another vinyl monomer, and the bromine atoms are added to a benzene ring with 1 to 5 bromine atoms, preferably 4 to 5 bromine atoms, added per benzene ring.

[0065] Examples of the benzyl acrylate containing a bromine atom include pentabromobenzyl acrylate, tetrabromobenzyl acrylate, tribromobenzyl acrylate, and mixtures thereof. Examples of the benzyl methacrylate containing a bromine atom include methacrylates corresponding to the above-mentioned acrylates.

[0066] Specific examples of other vinyl monomers that can be copolymerized with the bromine atom-containing benzyl (meth)acrylate include acrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, and benzyl acrylate; methacrylic acid, methyl methacrylate, ethyl methacrylate, butyl methacrylate, and benzyl methacrylate; unsaturated carboxylic acids or anhydrides thereof, such as styrene, acrylonitrile, fumaric acid, and maleic acid; vinyl acetate, and vinyl chloride.

[0067] These are usually used in an equimolar amount or less, particularly preferably 0.5 times the molar amount or less, relative to the bromine atom-containing benzyl (meth)acrylate.

[0068] Furthermore, examples of vinyl monomers that can be used include xylylene diacrylate, xylylene dimethacrylate, tetrabromo xylylene diacrylate, tetrabromo xylylene dimethacrylate, butadiene, isoprene, and divinylbenzene. These can usually be used in an amount of 0.5 or less by mole relative to the bromine atom-containing benzyl acrylate or benzyl methacrylate.

[0069] The brominated poly(meth)acrylate is preferably a polymer obtained by polymerizing a bromine atom-containing (meth)acrylate monomer, particularly benzyl (meth)acrylate, alone or by copolymerizing two or more kinds of the monomers, or by copolymerizing the monomers with other vinyl monomers. The bromine atoms are added to the benzene ring, and the number of added bromine atoms is preferably 1 to 5, more preferably 4 to 5, per benzene ring.

[0070] As the brominated poly(meth)acrylate, pentabromobenzyl poly(meth)acrylate is preferred due to its high bromine content.

[0071] The molecular weight of the brominated poly(meth)acrylate is arbitrary and may be appropriately selected and determined, but the weight average molecular weight (Mw) is preferably 3,000 or more, more preferably 10,000 or more, even more preferably 15,000 or more, even more preferably 20,000 or more, and even more preferably 25,000 or more. By making it equal to or greater than the lower limit, a molded product having higher mechanical strength tends to be obtained. In addition, the upper limit of the weight average molecular weight (Mw) is preferably equal to or less than 100,000, more preferably equal to or less than 80,000, even more preferably equal to or less than 60,000, even more preferably equal to or less than 50,000, and even more preferably equal to or less than 35,000. By making it equal to or less than the upper limit, the flowability of the resin composition tends to be further improved.

[0072] Specifically, the brominated polycarbonate is preferably a brominated polycarbonate obtained from, for example, brominated bisphenol A, particularly tetrabromobisphenol A. Examples of the terminal structure include a phenyl group, a 4-t-butylphenyl group, and a 2,4,6-tribromophenyl group, and in particular, one having a 2,4,6-tribromophenyl group in the terminal group structure is preferred.

[0073] The average number of carbonate constituent units in the brominated polycarbonate may be appropriately selected and determined, but is preferably 2-30, more preferably 3-15, and even more preferably 3-10.

[0074] The molecular weight of the brominated polycarbonate is optional and may be appropriately selected and determined, but it is preferably from 1,000 to 20,000, more preferably from 2,000 to 10,000, in terms of viscosity average molecular weight.

[0075] The brominated polycarbonate obtained from the above brominated bisphenol A can be obtained, for example, by a conventional method of reacting brominated bisphenol with phosgene. The end-capping agent includes an aromatic monohydroxy compound, which may be substituted with a halogen or an organic group.

[0076] Specific preferred examples of the brominated epoxy include bisphenol A type brominated epoxy compounds, such as tetrabromobisphenol A epoxy compounds and glycidyl brominated bisphenol A epoxy compounds.

[0077] The molecular weight of the brominated epoxy compound is arbitrary and may be appropriately selected and determined, but the weight average molecular weight (Mw) is preferably 3,000 or more, more preferably 10,000 or more, even more preferably 13,000 or more, even more preferably 15,000 or more, and even more preferably 18,000 or more. By making it equal to or more than the lower limit, a molded product having higher mechanical strength tends to be obtained. In addition, the upper limit of the weight average molecular weight (Mw) is preferably 100,000 or less, more preferably 80,000 or less, even more preferably 78,000 or less, even more preferably 75,000 or less, even more preferably 70,000 or less, and may be 50,000 or less, 30,000 or less, or 25,000 or less. By making it equal to or less than the upper limit, the flowability of the resin composition tends to be further improved. The brominated epoxy compound preferably has an epoxy equivalent of 3,000 to 40,000 g / eq, more preferably 4,000 to 35,000 g / eq, and particularly preferably 10,000 to 30,000 g / eq.

[0078] In addition, a brominated epoxy oligomer can be used in combination as the brominated epoxy. In this case, for example, by using an oligomer having Mw of 5,000 or less at a ratio of about 50 mass% or less, the flame retardancy, releasability, and flowability can be appropriately adjusted. The bromine atom content in the brominated epoxy compound is arbitrary, but in order to impart sufficient flame retardancy, it is usually 10 mass% or more, preferably 20 mass% or more, and particularly preferably 30 mass% or more, with the upper limit being 60 mass%, and preferably 55 mass% or less.

[0079] The brominated polystyrene preferably includes a brominated polystyrene containing a constitutional unit represented by the formula (3). [ka] (In formula (3), t is an integer of 1 to 5, and n is the number of constitutional units.)

[0080] Brominated polystyrene may be produced by brominating polystyrene or by polymerizing brominated styrene monomer, but the polymerized brominated styrene has a smaller amount of free bromine (atoms), and is therefore preferred. In formula (3), the CH group to which the brominated benzene is bonded may be substituted with a methyl group. Brominated polystyrene may also be a copolymer in which other vinyl monomers are copolymerized. Examples of the vinyl monomer in this case include styrene, α-methylstyrene, (meth)acrylonitrile, (meth)methyl acrylate, butadiene, and vinyl acetate. Brominated polystyrene may be used alone or as a mixture of two or more types with different structures, and may contain units derived from styrene monomers with different bromine numbers in a single molecular chain.

[0081] Specific examples of brominated polystyrene include poly(4-bromostyrene), poly(2-bromostyrene), poly(3-bromostyrene), poly(2,4-dibromostyrene), poly(2,6-dibromostyrene), poly(2,5-dibromostyrene), poly(3,5-dibromostyrene), poly(2,4,6-tribromostyrene), poly(2,4,5-tribromostyrene), poly(2,3,5-tribromostyrene), and poly(4-bromo-α-methylstyrene). Examples of suitable styrene copolymers include poly(2,4-dibromostyrene), poly(2,5-dibromo-α-methylstyrene), poly(2,4,6-tribromo-α-methylstyrene) and poly(2,4,5-tribromo-α-methylstyrene), of which poly(2,4,6-tribromostyrene), poly(2,4,5-tribromostyrene) and polydibromostyrene and polytribromostyrene containing an average of 2 to 3 bromine groups in the benzene ring are particularly preferred.

[0082] The number n (average degree of polymerization) of the constituent units in the formula (3) of the brominated polystyrene is preferably 30 to 1,500, more preferably 150 to 1,000, and particularly preferably 300 to 800. If the average degree of polymerization is less than 30, blooming is likely to occur, while if it exceeds 1,500, poor dispersion is likely to occur and mechanical properties are likely to deteriorate. The weight-average molecular weight (Mw) of the brominated polystyrene is preferably 5,000 to 500,000, more preferably 10,000 to 500,000, even more preferably 10,000 to 300,000, even more preferably 10,000 to 100,000, and even more preferably 10,000 to 70,000. In particular, in the case of the above-mentioned brominated polystyrene, the weight average molecular weight (Mw) is preferably 50,000 to 70,000, and in the case of brominated polystyrene produced by a polymerization method, the weight average molecular weight (Mw) is preferably about 10,000 to 30,000.

[0083] The bromine concentration in the bromine-based flame retardant is preferably 45% by mass or more, more preferably 48% by mass or more, even more preferably 50% by mass or more, may be 55% by mass or more, or may be 60% by mass or more. By setting it to the lower limit or more, the flame retardancy of the molded article tends to be effectively improved. The upper limit of the bromine concentration is preferably 85% by mass or less, more preferably 80% by mass or less, even more preferably 75% by mass or less, and may be 73% by mass or less.

[0084] The content of the halogen compound in the resin composition of the present embodiment is 0.1 parts by mass or more, preferably 0.5 parts by mass or more, more preferably 0.7 parts by mass or more, and even more preferably 1 part by mass or more, relative to 100 parts by mass of the total thermoplastic polyester resin. When flame retardancy is imparted to the resin composition, it is more preferably 5 parts by mass or more, even more preferably 8 parts by mass or more, and even more preferably 10 parts by mass or more. By making it equal to or more than the lower limit, the flame retardancy of the obtained molded product can be further improved, and the change in color tone tends to be more effectively suppressed. In addition, the upper limit of the content of the halogen compound is 30 parts by mass or less, preferably 25 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 15 parts by mass or less, relative to 100 parts by mass of the total thermoplastic polyester resin. When the resin composition is used for an application that does not require high flame retardancy, it is more preferably 10 parts by mass or less, even more preferably 7 parts by mass or less, even more preferably 5 parts by mass or less, particularly more preferably 4 or less, and even more particularly more preferably 3 parts by mass or less. By ensuring that the content is equal to or less than the upper limit, there is a tendency that changes in color tone of the resulting molded product can be more effectively suppressed, and a decrease in physical properties such as strength can be effectively suppressed. The resin composition of the present embodiment may contain only one type of halogen compound, or may contain two or more types. When two or more types are contained, the total amount is preferably in the above range.

[0085] In the resin composition of the present embodiment, the mass ratio of the halogen atoms contained in the halogen compound to the stabilizer, that is, the halogen atoms / stabilizer, is preferably 1.0 or more, more preferably 2.0 or more, and even more preferably 3.3 or more. By making it equal to or more than the lower limit, color tone change can be more effectively suppressed. Furthermore, when high flame retardancy is required for the resin composition, the halogen atoms / stabilizer is preferably 10 or more, more preferably 15 or more, even more preferably 20 or more, even more preferably 25 or more, even more preferably 30 or more, and particularly more preferably 35 or more. The upper limit of the halogen atoms / stabilizer is not particularly specified, but is usually 100 or less, 70 or less, 50 or less, 40 or less, 20 or less, and even 10 or less or 5 or less depending on the application, etc., will sufficiently satisfy the required performance.

[0086] <Other ingredients> The resin composition of the present embodiment may contain other components in addition to the above-mentioned components as necessary, as long as the desired physical properties are not significantly impaired. The other components may be contained alone or in any combination and ratio of two or more. Examples of other components include reinforcing fillers and resin additives. Specific examples of resin additives include flame retardant assistants, release agents, colorants (pigments, dyes), nucleating agents, reactive compounds, antistatic agents, antifogging agents, antiblocking agents, flow improvers, plasticizers, and dispersants. The total amount of these other components is preferably 0 to 10 mass %, more preferably 0 to 5 mass %, and even more preferably 0 to 3 mass %, based on 100 mass % of the resin composition. In the resin composition of the present embodiment, the total amount of the thermoplastic polyester resin, the stabilizer, the silver-containing antibacterial agent, the halogen compound, and other components that are blended as necessary is 100 mass %. In the resin composition of this embodiment, the total of the thermoplastic polyester resin, stabilizer, silver-containing antibacterial agent, halogen compound, flame retardant assistant and release agent preferably accounts for 90 mass% or more of the resin composition, more preferably 95 mass% or more, even more preferably 97 mass% or more, even more preferably 99 mass% or more, and is 100 mass% or less.

[0087] <<Flame retardant synergist>> The resin composition of the present embodiment may contain a flame retardant assistant. By containing a flame retardant assistant, the flame retardancy of the molded article can be further improved. The flame retardant assistant is particularly preferably used when a halogen-based flame retardant is contained. The flame retardant assistant used in the present embodiment is exemplified by antimony compounds, such as antimony trioxide (Sb 2 O 3 ), antimony pentoxide (Sb 2 O 5 ), sodium antimonate, etc. In particular, from the standpoint of flame retardancy and impact resistance, antimony oxide, particularly antimony trioxide, is preferred. When a flame retardant auxiliary is blended, it may be blended as a master batch. The content of the antimony compound in the master batch is preferably 30 to 90 mass%, more preferably 40 to 85 mass%, further preferably 50 to 85 mass%, even more preferably 60 to 85 mass%, and still more preferably 70 to 85 mass%. The resin used in the master batch is preferably a polyester resin, and more preferably a polybutylene terephthalate resin.

[0088] When the resin composition of the present embodiment contains a flame retardant auxiliary (for example, an antimony compound), the content is preferably 0.1 parts by mass or more, more preferably 1.0 parts by mass or more, even more preferably 3.0 parts by mass or more, even more preferably 4.0 parts by mass or more, and even more preferably 5.0 parts by mass or more, relative to 100 parts by mass of the thermoplastic polyester resin. By making the content equal to or more than the lower limit, the flame retardancy tends to be more effectively exhibited. In addition, the upper limit of the content of the antimony compound is preferably 20.0 parts by mass or less, more preferably 15.0 parts by mass or less, even more preferably 10.0 parts by mass or less, and even more preferably 8.0 parts by mass or less, relative to 100 parts by mass of the thermoplastic polyester resin. By making the content equal to or less than the upper limit, the impact resistance of the obtained molded product tends to be improved. The resin composition of the present embodiment may contain only one type of flame retardant auxiliary, or may contain two or more types. When two or more types are contained, the total amount is preferably in the above range.

[0089] <<Release agent>> The resin composition of the present embodiment may contain a release agent. Examples of the release agent include aliphatic carboxylic acids, salts of aliphatic carboxylic acids, esters of aliphatic carboxylic acids and alcohols, aliphatic hydrocarbon compounds having a number average molecular weight of 200 to 15,000, polysiloxane-based silicone oils, ketone waxes, and light amides, and aliphatic hydrocarbon compounds having a number average molecular weight of 200 to 15,000 are preferred.

[0090] Examples of the aliphatic carboxylic acid include saturated or unsaturated aliphatic mono-, di- or tri-carboxylic acids. Here, the aliphatic carboxylic acid also includes alicyclic carboxylic acids. Among these, preferred aliphatic carboxylic acids are mono- or di-carboxylic acids having 6 to 36 carbon atoms, and more preferred are saturated aliphatic mono-carboxylic acids having 6 to 36 carbon atoms. Specific examples of such aliphatic carboxylic acids include palmitic acid, stearic acid, caproic acid, capric acid, lauric acid, arachic acid, behenic acid, lignoceric acid, cerotic acid, melissic acid, tetralinic acid, montanic acid, adipic acid, and azelaic acid.

[0091] The aliphatic carboxylic acid in the ester of aliphatic carboxylic acid and alcohol can be, for example, the same as the aliphatic carboxylic acid. On the other hand, the alcohol can be, for example, a saturated or unsaturated monohydric or polyhydric alcohol. These alcohols may have a substituent such as a fluorine atom or an aryl group. Among these, a monohydric or polyhydric saturated alcohol having 30 or less carbon atoms is preferred, and an aliphatic saturated monohydric alcohol or an aliphatic saturated polyhydric alcohol having 30 or less carbon atoms is more preferred. Here, the term aliphatic is used to include alicyclic compounds. Specific examples of such alcohols include octanol, decanol, dodecanol, stearyl alcohol, behenyl alcohol, ethylene glycol, diethylene glycol, glycerin, pentaerythritol, 2,2-dihydroxyperfluoropropanol, neopentylene glycol, ditrimethylolpropane, and dipentaerythritol. The above ester may contain aliphatic carboxylic acid and / or alcohol as impurities. The above ester may be a pure substance, or may be a mixture of a plurality of compounds. The aliphatic carboxylic acid and alcohol that are combined to form an ester may each be one type, or two or more types may be used in any combination and ratio. Specific examples of esters of aliphatic carboxylic acids and alcohols include beeswax (a mixture mainly composed of myricyl palmitate), stearyl stearate, behenyl behenate, stearyl behenate, glycerin monopalmitate, glycerin monostearate, glycerin distearate, glycerin tristearate, pentaerythritol monopalmitate, pentaerythritol monostearate, pentaerythritol distearate, pentaerythritol tristearate, pentaerythritol tetrastearate, and rice wax.

[0092] Examples of aliphatic hydrocarbons having a number average molecular weight of 200 to 15,000 include liquid paraffin, paraffin wax, microwax, polyethylene wax, Fischer-Tropsch wax, and α-olefin oligomers having 3 to 12 carbon atoms. The aliphatic hydrocarbons also include alicyclic hydrocarbons. These hydrocarbons may be partially oxidized. Among these, microwax, paraffin wax, polyethylene wax or a partial oxide of polyethylene wax is preferred, and microwax is more preferred. The number average molecular weight of the aliphatic hydrocarbon is preferably 5,000 or less, and more preferably 400-1,000. The aliphatic hydrocarbon may be a single substance, but even if it is a mixture of substances having various constituent components and molecular weights, it is preferable that the main component is within the above range.

[0093] Examples of polysiloxane-based silicone oils include dimethyl silicone oil, methylphenyl silicone oil, diphenyl silicone oil, and fluorinated alkyl silicone.

[0094] For details about the release agent, please refer to paragraphs 0055 to 0061 of JP2018-095706A, the contents of which are incorporated herein by reference. When the resin composition of the present embodiment contains a release agent, the content thereof in the resin composition is preferably 0.05 to 3 parts by mass, more preferably 0.1 to 0.8 parts by mass, and further preferably 0.1 to 0.6 parts by mass. The resin composition of the present embodiment may contain only one type of release agent, or may contain two or more types. When two or more types are contained, the total amount is preferably in the above range.

[0095] <<Coloring agent>> The resin composition of the present embodiment may contain a colorant (dye and / or pigment). Examples of colorants that may be used in the present embodiment include inorganic pigments such as titanium oxide and carbon black, organic dyes, and organic pigments, and inorganic pigments are preferred.

[0096] Examples of inorganic pigments include sulfide pigments such as carbon black, cadmium red, and cadmium yellow; silicate pigments such as ultramarine; oxide pigments such as zinc white, red iron oxide, chromium oxide, iron black, titanium yellow, zinc-iron brown, titanium-cobalt green, cobalt green, cobalt blue, copper-chromium black, and copper-iron black; chromate pigments such as yellow lead and molybdate orange; and ferrocyanide pigments such as Prussian blue, with titanium oxide being preferred. Examples of organic pigments and organic dyes include phthalocyanine dyes or pigments such as copper phthalocyanine blue and copper phthalocyanine green; azo dyes or pigments such as nickel azo yellow; condensed polycyclic dyes or pigments such as thioindigo, perinone, perylene, quinacridone, dioxazine, isoindolinone, and quinophthalone; and anthraquinone, heterocyclic, and methyl dyes or pigments. The colorant may be blended in the form of a masterbatch. In this case, the concentration of the colorant in the masterbatch is 30 to 80% by mass. The thermoplastic resin to be blended in the masterbatch is, for example, a polyester resin.

[0097] The content of the colorant is preferably 0.01 parts by mass or more, more preferably 0.1 parts by mass or more, relative to 100 parts by mass of the thermoplastic resin, and is preferably 5.0 parts by mass or less, more preferably 3.0 parts by mass or less, and even more preferably 2.0 parts by mass or less, relative to 100 parts by mass of the thermoplastic resin. The resin composition may contain only one type of colorant, or may contain two or more types. When two or more types are contained, the total amount is preferably within the above range.

[0098] <Physical properties of resin composition> The resin composition of the present embodiment preferably has a small color change due to additives. Specifically, the difference (ΔE) between the color of the resin composition of the present embodiment and the color of the resin composition obtained by removing the stabilizer, antibacterial agent, and halogen compound from the resin composition is preferably 10 or less, more preferably 6 or less, even more preferably 5 or less, even more preferably 4 or less, and particularly preferably 3 or less. The lower limit of ΔE is 0 or more, and even if it is 0.1 or more, the required performance is satisfied.

[0099] The resin composition of the present embodiment preferably has excellent flame retardancy. For example, when the resin composition is molded into a test piece having a thickness of 0.8 mm and subjected to a UL-94 test, it preferably satisfies V-0. ΔE and flame retardancy are measured as described in the Examples section below.

[0100] <Method of producing resin composition> The resin composition of this embodiment can be produced by a conventional method for preparing a resin composition (e.g., pellets). Usually, the components and various additives added as desired are thoroughly mixed together and then melt-kneaded in a single-screw or twin-screw extruder. The resin composition of this embodiment can also be prepared without premixing the components, or by premixing only a portion of the components, feeding the components to an extruder using a feeder and melt-kneading them. A master batch may be prepared by melt-kneading a portion of the components of the silver-containing antibacterial agent or flame retardant auxiliary with a thermoplastic resin, and then blending the remaining components therein and melt-kneading them. The reinforcing filler (particularly glass fiber) is preferably fed from a side feeder midway through the cylinder of the extruder. The heating temperature during melt kneading can be appropriately selected from the range of 220 to 300°C. If the temperature is too high, decomposition gas is likely to be generated, which may cause opacity. Therefore, it is desirable to select a screw configuration that takes into account shear heat generation, etc.

[0101] <Method of manufacturing molded products> The resin composition or pellets of the present embodiment are molded according to a known method. The manufacturing method of the molded product is not particularly limited, and any molding method generally used for resin compositions can be used. Examples of such molding methods include injection molding, ultra-high speed injection molding, injection compression molding, two-color molding, gas-assisted hollow molding, molding using a heat-insulating mold, molding using a rapid heating mold, foam molding (including supercritical fluid), insert molding, IMC (in-mold coating molding), extrusion molding, sheet molding, thermoforming, rotational molding, lamination molding, press molding, blow molding, etc., and among these, injection molding is preferred. For details of the injection molding method, refer to paragraphs 0113 to 0116 of Japanese Patent No. 6183822, the contents of which are incorporated herein by reference. The mold temperature during molding such as injection molding is preferably 40 to 150°C.

[0102] <Application> The resin composition of the present embodiment is used as a molded product formed from the resin composition or pellets. The applications of the resin composition and pellets are not particularly limited, and they can be widely used for home appliances, electrical and electronic equipment materials, automobile materials, housing materials, and materials for manufacturing parts in other industrial fields. More specifically, it is preferably used for sanitary use parts such as kitchens, washrooms, toilets, and other wet area parts.

[0103] The discoloration suppression method of the present embodiment is a method for suppressing discoloration of a resin composition containing 0.001 to 10.0 parts by mass of a stabilizer and 0.1 to 10.0 parts by mass of a silver-containing antibacterial agent relative to 100 parts by mass of a thermoplastic resin, and includes blending 0.1 to 30 parts by mass of a halogen compound relative to 100 parts by mass of the thermoplastic resin. The details of the thermoplastic resin, stabilizer, silver-containing antibacterial agent, and halogen compound are the same as those described above, and the blending amounts and preferred ranges thereof are also the same. EXAMPLES

[0104] The present invention will be described in more detail below with reference to examples. The materials, amounts, ratios, processing contents, processing procedures, etc. shown in the following examples can be appropriately changed without departing from the spirit of the present invention. Therefore, the scope of the present invention is not limited to the specific examples shown below. If the measuring instruments used in the examples are difficult to obtain due to discontinuation or the like, measurements can be made using other instruments with equivalent performance.

[0105] 1. Raw materials The following raw materials were used: [Table 1-1] [Table 1-2]

[0106] <Free bromine content> The free bromine content was quantified by the combustion ion chromatography method described in JP 2013-057009 A, paragraph 0083. Specifically, the bromine-based flame retardant or resin composition was heated under an argon atmosphere at 270° C. for 10 minutes, and the amount of bromine generated was measured. The resin composition was heated using an automatic sample combustion apparatus "AQF-100" manufactured by Mitsubishi Chemical Analytech Co., Ltd., and the amount of bromine generated by heating the resin composition was measured using an "ICS-90" apparatus manufactured by Nippon Dionex Co., Ltd.

[0107] 2. Examples 1-1 to 1-13, 2-1 to 2-6, Comparative Examples 1-1 to 1-18, 2-1 to 2-6 <Compound> The components shown in Table 1 were mixed uniformly in a tumbler mixer in the ratios shown in Tables 2 to 6 (each component in Tables 2 to 6 is shown in parts by mass). The mixture obtained was fed to a twin-screw extruder ("TEX30α" manufactured by The Japan Steel Works, Ltd.) from the main feed port. The resin composition was melt-kneaded under conditions of a cylinder setting temperature of 260°C in the first kneading section and a screw rotation speed of 200 rpm, and was quenched in a water tank and pelletized using a pelletizer to obtain pellets of the resin composition.

[0108] <Color tone> The pellets obtained above were collected and left to stand for 24 hours or more in a room with a temperature of 23°C and a humidity of 50%, and then the color tone (L) was measured using a Nippon Denshoku Industries SE6000 model (light source: C / 2, reflected light). * , a * , b * ) was measured. The color difference ΔE of each resin composition pellet was calculated based on the resin composition pellet containing polybutylene terephthalate resin and a release agent (Comparative Example 1-1).

[0109] <Flame retardancy (only Examples 2-1 to 2-6 and Comparative Examples 2-1 to 2-6)> The pellets obtained above were dried at 110°C for 5 hours, and then injection molded into combustion test specimens (12.7 mm width x 127 mm length x 0.8 mm thickness) using an injection molding machine (Japan Steel Works, Ltd., "J-50AD") under conditions of a cylinder temperature of 250°C and a mold temperature of 80°C. The obtained combustion test specimens were left to stand in an atmosphere of 70°C for one week, and then the flame retardancy was evaluated according to the Underwriters Laboratories Subject 94 (UL94) method.

[0110] <Antibacterial> The pellets obtained above were used to produce molded pieces (length 100 mm × width 100 mm × thickness 2 mm) using an injection molding machine (NEX-80, manufactured by Nissei Plastic Industrial Co., Ltd.) under conditions of a resin temperature of 250° C. and a mold temperature of 80° C. The molded pieces obtained were cut to a length of 50 mm × width of 50 mm to obtain test pieces. Antibacterial testing was conducted in accordance with JIS Z 2801. The test specimen was placed in a petri dish, 0.4 mL of Escherichia coli or Staphylococcus epidermidis test bacteria solution was dropped, a film (40 mm x 40 mm) was placed over the dish, and the dish was then covered with a lid. The dish was left to stand at 35°C and 90% RH or higher for 24 hours for incubation. After that, 10 mL of lecithin-sorbate 80-added soybean-casein-digest agar (SCDLP) medium was added to wash out the test bacteria from the film and the test specimen, and the number of bacteria in the liquid was measured using the agar plate culture method, and the antibacterial activity value was calculated according to formula (a). Formula (a) Antibacterial activity value = log(1cm of untreated sample) 2 (per cm of processed sample) - log(number of viable bacteria after incubation) 2 (number of live bacteria per 100 ml after incubation) Antibacterial activity value ≧ 2.0:+ Antibacterial Antibacterial activity value < 2.0:- No antibacterial properties

[0111] Before conducting the above antibacterial test, the test specimen was (Water resistance) Immerse in 50±10mL of deionized or distilled water at room temperature for 16 to 18 hours, or (Light resistance) 10±0.5 hours of light exposure with a xenon weather meter, or 8±0.5 hours of light exposure with a sunshine weather meter Pre-processing of (1) E. coli - Water resistant (2) E. coli - Light resistance (3) Staphylococcus aureus - Water-resistant (4) Staphylococcus aureus, light-resistant In the four conditions, Those whose antibacterial activity value was ≥ 2.0 under all conditions were rated as A, and those whose antibacterial activity value was < 2.0 under any condition were rated as B.

[0112] <Thermal stability> The pellets obtained above were molded into dumbbell test pieces conforming to ISO527 using an injection molding machine (manufactured by Japan Steel Works, J85-AD) under conditions of a resin temperature of 250°C and a mold temperature of 80°C. The dumbbell test pieces were then left to stand for 500 hours at a temperature of 120°C using a thermostatic testing machine (manufactured by Espec Corporation). A tensile test was then carried out conforming to ISO527. Test pieces with a tensile strength retention rate of 80% or more after the heat treatment relative to the test pieces before the heat treatment were rated as A, and those with a tensile strength retention rate of less than 80% were rated as B.

[0113] <Retention thermal stability> The pellets obtained above were used in an injection molding machine (Nissei Plastic Industrial Co., Ltd., NEX-80) to produce a "retention molding plate" (length 100 mm x width 100 mm x thickness 2 mm) under conditions of a cylinder temperature of 270°C, a mold temperature of 80°C, and a cooling time of 300 seconds. In addition, the pellets obtained above were used in an injection molding machine (Nissei Plastic Industrial Co., Ltd., NEX-80) to produce a "reference plate" (length 100 mm x width 100 mm x thickness 2 mm) under conditions of a cylinder temperature of 270°C, a mold temperature of 80°C, and a cooling time of 15 seconds. The color tone of the obtained plate was measured using a spectrophotometer (CM-36dg, manufactured by Konica Minolta) (L * , a * , b * The color difference ΔE of the "retention molded plate" against the "reference plate" was calculated, and a ΔE of less than 1 was rated A, a ΔE of 1 or more but less than 3 was rated B, and a ΔE of 3 or more was rated C.

[0114] [Table 2]

[0115] [Table 3]

[0116] [Table 4]

[0117] [Table 5]

[0118] TIFF0007679919000011.tif159170

[0119] [Table 6]

[0120] In the above table, the content of "antibacterial agent" refers to the content of the antibacterial agent itself in the resin composition, and does not include the resin component in which the antibacterial agent is made into a masterbatch. In the above table, the content of "halogen atom" means the content of the halogen itself contained in the halogen compound. In the above table, the content "halogen atom / stabilizer" indicates the mass ratio of the halogen atoms contained in the halogen compound to the stabilizer.

[0121] As is clear from the above results, the resin composition of the present embodiment has a good balance of antibacterial properties, thermal stability, and color stability. Furthermore, by increasing the content of the flame retardant, it is possible to achieve excellent flame retardancy while maintaining a good balance of antibacterial properties, thermal stability, and color stability.

Claims

1. For 100 parts by mass of thermoplastic resin, 0.001 to 1.0 parts by mass of a stabilizer; 0.1 to 10.0 parts by mass of an antibacterial agent containing silver; and 0.1 to 30 parts by mass of a halogen compound; Resin composition.

2. The resin composition according to claim 1 , wherein a mass ratio of halogen atoms contained in the resin composition to the stabilizer, that is, halogen atoms / stabilizer, is 1.0 or more.

3. The thermoplastic resin includes a thermoplastic polyester resin. The resin composition according to claim 1.

4. The thermoplastic polyester resin includes a polybutylene terephthalate resin. The resin composition according to claim 3.

5. The resin composition according to claim 1 , wherein the stabilizer comprises one or more compounds selected from the group consisting of thioether compounds, hindered phenol compounds, and phosphite compounds.

6. The resin composition according to claim 1 , wherein the stabilizer comprises a thioether compound.

7. The resin composition according to claim 1 , wherein the silver-containing antibacterial agent comprises an inorganic silver-based antibacterial agent.

8. The resin composition of claim 1 , wherein the silver-containing antimicrobial agent comprises a glass-based antimicrobial agent.

9. The resin composition according to claim 1 , wherein the halogen compound contains a bromine atom and / or a fluorine atom.

10. The resin composition according to claim 1 , wherein the halogen compound contains a fluorine atom.

11. The resin composition according to claim 1 , wherein the halogen compound contains a bromine atom.

12. The resin composition according to claim 11, wherein the halogen compound has a free bromine content of 0.5 mass% or more.

13. a mass ratio of halogen atoms contained in the resin composition to the stabilizer, that is, halogen atoms / stabilizer, is 1.0 or more; the thermoplastic resin comprises a polybutylene terephthalate resin, the stabilizer comprises one or more compounds selected from the group consisting of hindered phenol compounds and phosphite compounds; the silver-containing antibacterial agent comprises a glass-based antibacterial agent; The halogen compound contains a bromine atom and / or a fluorine atom. The resin composition according to claim 1.

14. A pellet of the resin composition according to any one of claims 1 to 13.

15. A molded article formed from the resin composition according to any one of claims 1 to 13.

16. A molded article formed from the pellets of claim 14.

17. 16. The molded article according to claim 15, which is a part for sanitary use.

18. A method for inhibiting discoloration of a resin composition containing 0.001 to 1.0 part by mass of a stabilizer and 0.1 to 10.0 parts by mass of a silver-containing antibacterial agent relative to 100 parts by mass of a thermoplastic resin, the method comprising blending 0.1 to 30 parts by mass of a halogen compound relative to 100 parts by mass of the thermoplastic resin.

19. A method for inhibiting discoloration of a resin composition containing 0.01 to 1.0 part by mass of a stabilizer and 0.1 to 3.0 parts by mass of an antibacterial agent containing silver per 100 parts by mass of a thermoplastic polyester resin, the method comprising blending 0.1 to 30 parts by mass of a halogen compound per 100 parts by mass of the thermoplastic polyester resin.

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