Resin composition and molded article

Abstract

To provide a resin composition having excellent antibacterial activity and suppressed discoloration under a wet heat environment and to provide a molded body formed from the resin composition.SOLUTION: There is provided a resin composition which comprises 0.05 to 3.00 pts.mass of an antibacterial agent (B), 0.05 to 3.00 pts.mass of an ionomer containing zinc ions and / or magnesium ions (C) and 0.005 to 1.00 pt.mass of a phosphorus compound containing trivalent phosphorus (D) based on 100 pts.mass of a thermoplastic resin (A), wherein the antibacterial agent (B) contains one or more carriers selected from the group consisting of glass, calcium apatite, silica gel, calcium silicate, magnesium aluminate silicate, silica, alumina and thiosulfite which support silver atoms and / or silver ions and silver atoms and / or silver ions.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This invention relates to resin compositions and molded articles. [Background technology]

[0002] Thermoplastic resins are widely used in various applications due to their lightweight nature and excellent mechanical properties.

[0003] In applications such as food processing, water-related applications, and medical applications, antibacterial properties are required for molded articles made from thermoplastic resins. To impart antibacterial properties to thermoplastic resins, it is conceivable to incorporate antibacterial agents. For example, a resin composition containing polyacetal resin, an inorganic antibacterial agent, and a polyester resin has been proposed (Patent Document 1). [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-128468 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] As mentioned above, antibacterial properties are increasingly required for molded articles made from thermoplastic resins. However, it has been found that when antibacterial agents are added to impart antibacterial properties, discoloration in humid and hot environments can become a problem. The present invention aims to provide a resin composition that exhibits excellent antibacterial properties and suppresses discoloration in a humid and hot environment, as well as a molded article formed from the resin composition, under such conditions. [Means for solving the problem]

[0006] Based on the above-mentioned problems, the inventors conducted research and found that the above-mentioned problems can be solved by combining a specific antibacterial agent, an ionomer, and a stabilizer with a thermoplastic resin. Specifically, the above problem was solved by the following means. <1> A resin composition comprising 100 parts by mass of thermoplastic resin (A), 0.05 to 3.00 parts by mass of an antimicrobial agent (B), 0.05 to 3.00 parts by mass of an ionomer (C) containing zinc ions and / or magnesium ions, and 0.005 to 1.00 parts by mass of a phosphorus compound (D) containing trivalent phosphorus, wherein the antimicrobial agent (B) comprises silver atoms and / or silver ions, and one or more carriers selected from the group consisting of glass, calcium apatite, silica gel, calcium silicate, magnesium aluminosilicate, silica, alumina, and thiosulfite, on which the silver atoms and / or silver ions are supported. <2> The thermoplastic resin includes at least one of polyacetal resin, polyamide resin, polyester resin, polyphenylene ether resin, and polycarbonate resin. <1> The resin composition described above. <3> The thermoplastic resin includes a polyacetal resin. <1> The resin composition described above. <4> The aforementioned carrier includes glass, <1> ~ <3> A resin composition as described in any one of the following. <5> The ionomer (C) contains zinc ions. <1> ~ <4> A resin composition as described in any one of the following. <6> The phosphorus compound (D) comprises triphenylphosphine. <1> ~ <5> A resin composition as described in any one of the following. <7> <1> ~ <6> A molded article formed from any one of the resin compositions described above. [Effects of the Invention]

[0007] The present invention makes it possible to provide a resin composition that exhibits excellent antibacterial properties and suppresses discoloration in a humid and hot environment, as well as a molded article formed from the resin composition. [Modes for carrying out the invention]

[0008] Hereinafter, embodiments for implementing the present invention (hereinafter simply referred to as "the present embodiment") will be described in detail. Note that the following present embodiment is an exemplification for explaining the present invention, and the present invention is not limited only to the present embodiment. In this specification, "~" is used to mean including the numerical values described before and after it as the lower limit value and the upper limit value. In this specification, various physical property values and characteristic values are assumed to be those at 23°C unless otherwise specified. In this specification, ppm means mass ppm. When the measurement methods and the like described according to the standards shown in this specification differ depending on the year, unless otherwise specified, they are based on the standards as of January 1, 2021.

[0009] The resin composition of the present embodiment contains, per 100 parts by mass of the thermoplastic resin, 0.05 to 3.00 parts by mass of an antibacterial agent (B), 0.05 to 3.00 parts by mass of an ionomer (C) containing zinc ions and / or magnesium ions, and 0.005 to 1.00 parts by mass of a phosphorus compound (D) containing trivalent phosphorus. The antibacterial agent (B) contains silver atoms and / or silver ions, and one or more carriers selected from the group consisting of glass, calcium apatite, silica gel, calcium silicate, magnesium aluminum silicate, silica, alumina, and thiosulfite that carry the silver atoms and / or silver ions. By adopting such a configuration, a resin composition excellent in antibacterial properties and suppressed in discoloration under a humid heat environment can be obtained. When an antibacterial agent containing silver atoms and / or silver ions is blended into a thermoplastic resin, silver ions of the antibacterial agent contained in the resin composition elute in a humid heat environment. Excessive elution of silver ions is considered to cause discoloration due to the reaction of silver ions with surrounding basic substances. In the resin composition of the present embodiment, it is presumed that elution of silver ions in a humid heat environment is suppressed by partial substitution of silver ions of the antibacterial agent by metal ions contained in an ionomer. And, the elution of silver ions can be suppressed by appropriately coordinating a phosphorus compound containing trivalent phosphorus with silver ions, and further, by selecting an ionomer that is less likely to hydrolyze to generate an acid or an alkali, it is presumed that discoloration in a humid heat environment and decomposition of the resin at high temperature can be suppressed while maintaining antibacterial properties.

[0010] <Thermoplastic resin resin (A)> The resin composition of the present embodiment contains a thermoplastic resin. The thermoplastic resin may be a crystalline thermoplastic resin or an amorphous thermoplastic resin, but a crystalline thermoplastic resin is preferred. Examples of the thermoplastic resin used in the present embodiment preferably include polyester resins (thermoplastic polyester resins); polyamide resins; polycarbonate resins; polystyrene resins; polyolefin resins such as polyethylene resins, polypropylene resins, and cyclic olefin resins; polyacetal resins; polyimide resins; polyetherimide resins; polyurethane resins; polyphenylene ether resins; polyphenylene sulfide resins; polysulfone resins; polymethacrylate resins; and the like. In the present embodiment, the thermoplastic resin preferably contains at least one of polyacetal resin, polyamide resin, polyester resin, polyphenylene ether resin, and polycarbonate resin, more preferably contains at least one of polyacetal resin, polyamide resin, and polyester resin, and even more preferably contains polyacetal resin.

[0011] <<Polyacetal resin>> The resin composition of this embodiment preferably contains a polyacetal resin. Polyacetal resins are easily decomposed under acidic or alkaline conditions, and are particularly easily decomposed under acidic or strongly alkaline conditions, increasing the amount of formaldehyde generated. Therefore, it was hypothesized that the decomposition of the polyacetal resin and the generation of formaldehyde could be suppressed by selecting an antimicrobial agent that has fewer acidic groups on its surface and / or does not act as a Lewis acid. Furthermore, it was hypothesized that the decomposition of the polyacetal resin and the generation of formaldehyde could be suppressed by selecting an ionomer that does not generate strong alkali through hydrolysis and that captures formic acid produced by the oxidation of formaldehyde. In other words, the resin composition of this embodiment provides a resin composition that exhibits excellent antibacterial properties, suppresses the generation of formaldehyde, and suppresses discoloration in a humid and hot environment, even when it contains polyacetal resin.

[0012] The polyacetal resin used in this embodiment is not particularly limited and may be a homopolymer containing only divalent oxymethylene groups as constituent units, or a copolymer containing divalent oxymethylene groups and divalent oxyalkylene groups having 2 to 6 carbon atoms as constituent units.

[0013] Examples of oxyalkylene groups having 2 to 6 carbon atoms include oxyethylene, oxypropylene, and oxybutylene groups.

[0014] In polyacetal resins, the proportion of oxyalkylene groups having 2 to 6 carbon atoms to the total number of moles of oxymethylene groups and oxyalkylene groups having 2 to 6 carbon atoms is not particularly limited and can be 0.5 to 10 mol%.

[0015] Trioxane is typically used as the main raw material for the production of the above-mentioned polyacetal resin. In addition, cyclic formals or cyclic ethers can be used to introduce oxyalkylene groups having 2 to 6 carbon atoms into the polyacetal resin. Specific examples of cyclic formals include 1,3-dioxolane, 1,3-dioxepane, 1,3-dioxocan, 1,3,5-trioxepane, and 1,3,6-trioxocan, while specific examples of cyclic ethers include ethylene oxide, propylene oxide, and butylene oxide. To introduce an oxyethylene group into the polyacetal resin, 1,3-dioxolane can be used as the main raw material; to introduce an oxypropylene group, 1,3-dioxane can be used as the main raw material; and to introduce an oxybutylene group, 1,3-dioxepane can be used as the main raw material. Furthermore, in polyacetal resins, it is preferable to have a low amount of hemiformal end groups, formyl end groups, and end groups that are unstable to heat, acid, and base. Here, a hemiformal end group is represented by -OCH2OH, and a formyl end group is represented by -CHO.

[0016] In addition to the above, polyacetal resins described in paragraphs 0018 to 0043 of Japanese Patent Publication No. 2015-074724 can be used as polyacetal resins, and these contents are incorporated herein by reference.

[0017] The melt index of the polyacetal resin (ASTM-D1238 standard: 190°C, 2.16 kg) is preferably between 1.0 g / 10 min and 100 g / 10 min.

[0018] <<Polyamide resin>> The polyamide resin is a polymer whose constituent units are acid amides obtained by ring-opening polymerization of lactams, polycondensation of aminocarboxylic acids, or polycondensation of diamines and dibasic acids, and may be an aliphatic polyamide resin or a semi-aromatic polyamide resin. Specifically, examples include polyamides 6, 11, 12, 46, 66, 610, 612, 6I, 6 / 66, 6T / 6I, 6 / 6T, 66 / 6T, 66 / 6T / 6I, 9T, 10T, xylylenediamine-based polyamide resins (details to be described later), polytrimethylhexamethylene terephthalamide, polybis(4-aminocyclohexyl)methanedodecamamide, polybis(3-methyl-4-aminocyclohexyl)methanedodecamamide, and polyundemethylenehexahydroterephthalamide. Note that "I" indicates the isophthalic acid component and "T" indicates the terephthalic acid component. Furthermore, for polyamide resins, reference can be made to paragraphs 0011-0013 of Japanese Patent Application Publication No. 2011-132550, which are incorporated herein by reference.

[0019] The polyamide resin used in this embodiment is composed of diamine-derived structural units and dicarboxylic acid-derived structural units, and a xylylenediamine-based polyamide resin is preferred in which 50 mol% or more of the diamine-derived structural units are derived from xylylenediamine. More preferably, 70 mol% or more, even more preferably 80 mol% or more, even more preferably 90 mol% or more, and even more preferably 95 mol% or more of the diamine-derived structural units of the xylylenediamine-based polyamide resin are derived from at least one of meta-xylylenediamine and para-xylylenediamine. More preferably, 50 mol% or more, more preferably 70 mol% or more, even more preferably 80 mol% or more, even more preferably 90 mol% or more, and even more preferably 95 mol% or more, the dicarboxylic acid-derived structural units of the xylylenediamine-based polyamide resin are derived from α,ω-linear aliphatic dicarboxylic acids having 4 to 20 carbon atoms. α,ω-linear aliphatic dibasic acids having 4 to 20 carbon atoms can be suitably used, such as adipic acid, sebacic acid, suberic acid, dodecanediic acid, and eicodionic acid, with adipic acid and sebacic acid being more preferred.

[0020] Diamines other than meta-xylylenediamine and para-xylylenediamine that can be used as raw material diamine components for xylylenediamine-based polyamide resins include aliphatic diamines such as tetramethylenediamine, pentamethylenediamine, 2-methylpentanediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, dodecamethylenediamine, 2,2,4-trimethyl-hexamethylenediamine, and 2,4,4-trimethylhexamethylenediamine, as well as 1,3-bis( Examples include alicyclic diamines such as aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, 1,3-diaminocyclohexane, 1,4-diaminocyclohexane, bis(4-aminocyclohexyl)methane, 2,2-bis(4-aminocyclohexyl)propane, bis(aminomethyl)decalin, and bis(aminomethyl)tricyclodecane, as well as aromatic ring-containing diamines such as bis(4-aminophenyl) ether, paraphenylenediamine, and bis(aminomethyl)naphthalene. One or more of these can be used in combination.

[0021] Examples of dicarboxylic acid components other than the above-mentioned α,ω-linear aliphatic dicarboxylic acids having 4 to 20 carbon atoms include phthalate compounds such as isophthalic acid, terephthalic acid, and orthophthalic acid, and isomers of naphthalenedicarboxylic acids such as 1,2-naphthalenedicarboxylic acid, 1,3-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 1,6-naphthalenedicarboxylic acid, 1,7-naphthalenedicarboxylic acid, 1,8-naphthalenedicarboxylic acid, 2,3-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, and 2,7-naphthalenedicarboxylic acid. One or more of these can be used in combination.

[0022] <<Polyester resin>> As the polyester resin, known thermoplastic polyester resins can be used, with polyethylene terephthalate resin and polybutylene terephthalate resin being preferred, and more preferably containing at least polybutylene terephthalate resin. The polybutylene terephthalate resin used in the resin composition of this embodiment is a polyester resin having a structure in which terephthalic acid units and 1,4-butanediol units are ester-bonded, and includes, in addition to the polybutylene terephthalate resin (homopolymer), a polybutylene terephthalate copolymer containing other copolymer components other than terephthalic acid units and 1,4-butanediol units, or a mixture of the homopolymer and the polybutylene terephthalate copolymer.

[0023] Polybutylene terephthalate resin may contain one or more dicarboxylic acid units other than terephthalic acid. Other specific examples of dicarboxylic acids include aromatic dicarboxylic acids such as 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, bis(4,4'-carboxyphenyl)methane, anthracenedicarboxylic acid, and 4,4'-diphenyletherdicarboxylic acid; alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid and 4,4'-dicyclohexyldicarboxylic acid; and aliphatic dicarboxylic acids such as adipic acid, sebacic acid, azelaic acid, and dimer acid. In this embodiment, the polybutylene terephthalate resin preferably contains terephthalic acid units accounting for 80 mol% or more of the total dicarboxylic acid units, and more preferably 90 mol% or more.

[0024] The diol unit may include one or more other diol units in addition to 1,4-butanediol. Other specific examples of diol units include aliphatic or alicyclic diols with 2 to 20 carbon atoms, and bisphenol derivatives. Specific examples include ethylene glycol, propylene glycol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, decamethylene glycol, cyclohexanedimethanol, 4,4'-dicyclohexylhydroxymethane, 4,4'-dicyclohexylhydroxypropane, and ethylene oxide addition diols of bisphenol A. In addition to the bifunctional monomers mentioned above, small amounts of trifunctional monomers such as trimellitic acid, trimesic acid, pyromellitic acid, pentaerythritol, and trimethylolpropane can be used to introduce branched structures, and small amounts of monofunctional compounds such as fatty acids can be used to adjust molecular weight. In this embodiment, the polybutylene terephthalate resin preferably contains 1,4-butanediol units accounting for 80 mol% or more of the total diol units, and more preferably 90 mol% or more.

[0025] As described above, the polybutylene terephthalate resin is preferably a polybutylene terephthalate homopolymer obtained by polycondensation of terephthalic acid and 1,4-butanediol. Alternatively, it may be a polybutylene terephthalate copolymer containing one or more dicarboxylic acids other than terephthalic acid as the carboxylic acid unit and / or one or more diols other than 1,4-butanediol as the diol unit. When the polybutylene terephthalate resin is a polybutylene terephthalate resin modified by copolymerization, 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. Among these, it is preferable to use a polyester ether resin copolymerized with polytetramethylene glycol. These copolymers refer to those with a copolymerization amount of 1 mol% or more and less than 50 mol% of the total segments of the polybutylene terephthalate resin. In particular, the copolymerization amount is preferably 2 mol% or more and less than 50 mol%, more preferably 3 to 40 mol%, and even more preferably 5 to 20 mol%. Such copolymerization ratios tend to improve fluidity and toughness, and are therefore preferable.

[0026] The amount of terminal carboxyl groups in polybutylene terephthalate resin can 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. Keeping it below the above upper limit tends to improve alkali resistance and hydrolysis resistance. There is no specific lower limit for the amount of terminal carboxyl groups, but considering the productivity of polybutylene terephthalate resin production, it is usually 10 eq / ton or more.

[0027] The amount of terminal carboxyl groups in polybutylene terephthalate resin is measured by dissolving 0.5 g of polybutylene terephthalate 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 conventionally known method, such as adjusting polymerization conditions like the raw material ratio, polymerization temperature, and reduced pressure method during polymerization, or by reacting with a chelating agent.

[0028] The intrinsic viscosity of the polybutylene terephthalate resin is preferably 0.5 to 2 dL / g. From the viewpoint of moldability and mechanical properties, an intrinsic viscosity in the range of 0.6 to 1.5 dL / g is more preferable. Setting the intrinsic viscosity to 0.5 dL / g or higher tends to further improve the mechanical strength of the resulting resin composition. Conversely, setting it to 2 dL / g or lower tends to further improve the fluidity of the resin composition and thus improve moldability. The intrinsic viscosity of polybutylene terephthalate resin is measured at 30°C in a 1:1 (mass ratio) mixed solvent of tetrachloroethane and phenol.

[0029] Polybutylene terephthalate resin can be produced by melt polymerization of a dicarboxylic acid component mainly composed of terephthalic acid or ester derivatives thereof, and a diol component mainly composed of 1,4-butanediol, in a batch or continuous manner. Furthermore, after producing a low molecular weight polybutylene terephthalate resin by melt polymerization, the degree of polymerization (or molecular weight) can be increased to a desired value by further solid-phase polymerization under a nitrogen atmosphere or reduced pressure. The polybutylene terephthalate resin is preferably obtained by a manufacturing method in which a dicarboxylic acid component mainly composed of terephthalic acid and a diol component mainly composed of 1,4-butanediol are continuously melt-polycondensed.

[0030] The catalyst used in carrying out the esterification reaction may be one of the conventionally known ones, such as titanium compounds, tin compounds, magnesium compounds, and calcium compounds. 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.

[0031] In addition to the above, the description in paragraphs 0013 to 0016 of Japanese Patent Publication No. 2010-174223 can be given to the polyester resin, and its contents are incorporated herein by reference.

[0032] <<Polyphenylene ether resin>> In this embodiment, known polyphenylene ether resins can be used, for example, polymers having a main chain of structural units represented by the following formula (preferably polymers in which the structural units represented by the following formula account for 90 mol% or more of all structural units excluding terminal groups). The polyphenylene ether resin may be either a homopolymer or a copolymer.

[0033] [ka] (In the formula, two R a Each of these independently represents a hydrogen atom, a halogen atom, a primary or secondary alkyl group, an aryl group, an aminoalkyl group, a halogenated alkyl group, a hydrocarbon oxy group, or a halogenated hydrocarbon oxy group, and the two R b Each of these independently represents a hydrogen atom, a halogen atom, a primary or secondary alkyl group, an aryl group, a halogenated alkyl group, a hydrocarbon oxy group, or a halogenated hydrocarbon oxy group. However, two R a (They cannot both become hydrogen atoms.)

[0034] R a and R b As for the group, a hydrogen atom, a primary or secondary alkyl group, or an aryl group are preferred, independently of each other. Preferred examples of primary alkyl groups include methyl, ethyl, n-propyl, n-butyl, n-amyl, isoamyl, 2-methylbutyl, 2,3-dimethylbutyl, 2-, 3- or 4-methylpentyl, or heptyl groups. Preferred examples of secondary alkyl groups include, for example, isopropyl, sec-butyl, or 1-ethylpropyl. In particular, R a It is preferable that R is a primary or secondary alkyl group or phenyl group having 1 to 4 carbon atoms. b It is preferable that it is a hydrogen atom.

[0035] Suitable homopolymers of polyphenylene ether resins include, for example, polymers of 2,6-dialkylphenylene ethers such as poly(2,6-dimethyl-1,4-phenylene) ether, poly(2,6-diethyl-1,4-phenylene ether), poly(2,6-dipropyl-1,4-phenylene ether), poly(2-ethyl-6-methyl-1,4-phenylene ether), and poly(2-methyl-6-propyl-1,4-phenylene ether). Examples of copolymers include 2,6-dimethylphenol / 2,3,6-trimethylphenol copolymers, 2,6-dimethylphenol / 2,3,6-triethylphenol copolymers, 2,6-diethylphenol / 2,3,6-trimethylphenol copolymers, 2,6-dipropylphenol / 2,3,6-trimethylphenol copolymers, and other 2,6-dialkylphenol / 2,3,6-trialkylphenol copolymers; graft copolymers obtained by graft polymerization of styrene onto poly(2,6-dimethyl-1,4-phenylene ether); and graft copolymers obtained by graft polymerization of styrene onto 2,6-dimethylphenol / 2,3,6-trimethylphenol copolymers.

[0036] In this embodiment, poly(2,6-dimethyl-1,4-phenylene) ether and 2,6-dimethylphenol / 2,3,6-trimethylphenol random copolymers are particularly preferred as the polyphenylene ether resin. Polyphenylene ether resins with specified terminal group counts and copper content, as described in Japanese Patent Application Publication No. 2005-344065, can also be suitably used.

[0037] The polyphenylene ether resin is preferably one with an intrinsic viscosity of 0.2 to 0.8 dL / g, and more preferably 0.3 to 0.6 dL / g, measured in chloroform at 30°C. A viscosity of 0.2 dL / g or higher tends to improve the mechanical strength of the molded article, while a viscosity of 0.8 dL / g or lower tends to improve the fluidity of the resin composition, making molding easier. Alternatively, two or more polyphenylene ether resins with different intrinsic viscosities may be used in combination to achieve this viscosity range.

[0038] The method for producing the polyphenylene ether resin used in this embodiment is not particularly limited, and a known method can be employed, for example, by oxidative polymerization of a monomer such as 2,6-dimethylphenol in the presence of an amine copper catalyst. In this case, the intrinsic viscosity can be controlled to a desired range by selecting the reaction conditions. Control of the intrinsic viscosity can be achieved by selecting conditions such as polymerization temperature, polymerization time, and catalyst amount.

[0039] <<Polycarbonate resin>> Polycarbonate resin is a branched homopolymer or copolymer obtained by reacting a dihydroxy compound, or a small amount thereof, with a polyhydroxy compound with phosgene or a diester carbonate. The method for producing polycarbonate resin is not particularly limited, and conventionally known methods such as the phosgene method (interfacial polymerization) or the melting method (transesterification) can be used.

[0040] As the raw material dihydroxy compound, aromatic dihydroxy compounds are preferred, including 2,2-bis(4-hydroxyphenyl)propane (=bisphenol A), tetramethylbisphenol A, bis(4-hydroxyphenyl)-p-diisopropylbenzene, hydroquinone, resorcinol, 4,4-dihydroxydiphenyl, and others, with bisphenol A being preferred. In addition, compounds in which one or more tetraalkylphosphonium sulfonates are bonded to the above aromatic dihydroxy compounds can also be used.

[0041] Among the polycarbonate resins mentioned above, aromatic polycarbonate resins derived from 2,2-bis(4-hydroxyphenyl)propane, or aromatic polycarbonate copolymers derived from 2,2-bis(4-hydroxyphenyl)propane and other aromatic dihydroxy compounds are preferred. Alternatively, copolymers mainly composed of aromatic polycarbonate resins, such as copolymers with polymers or oligomers having a siloxane structure, may also be used. Furthermore, two or more of the above-mentioned polycarbonate resins may be mixed and used.

[0042] To adjust the molecular weight of polycarbonate resin, monovalent aromatic hydroxy compounds can be used, such as m- and p-methylphenol, m- and p-propylphenol, p-tert-butylphenol, and p-long-chain alkyl-substituted phenols.

[0043] The viscosity-average molecular weight (Mv) of the polycarbonate resin is preferably 5,000 or more, more preferably 10,000 or more, and even more preferably 13,000 or more. Using a resin with a viscosity-average molecular weight of 5,000 or more tends to improve the mechanical strength of the resulting resin composition. Furthermore, the viscosity-average molecular weight (Mv) of the polycarbonate resin is preferably 60,000 or less, more preferably 40,000 or less, and even more preferably 30,000 or less. Using a resin with a viscosity-average molecular weight of 60,000 or less tends to improve the fluidity of the resin composition and improve its moldability. When the mixture contains two or more types of polycarbonate resin, it is preferable that the mixture satisfies the above range (the same consideration applies to molecular weight below).

[0044] In this embodiment, the viscosity-average molecular weight (Mv) of the polycarbonate resin is calculated using an Ubbelohde viscometer to determine the intrinsic viscosity ([η]) of the methylene chloride solution of the polycarbonate resin at 20°C, and the value is derived from Schnell's viscosity formula. [η] = 1.23 × 10 -4 Mv0.83

[0045] 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 melt method (transesterification method) can be used. Further, a polycarbonate resin obtained by subjecting a polycarbonate resin produced by the melt method to a post-treatment for adjusting the amount of terminal OH groups is also preferable.

[0046] The resin composition of the present embodiment preferably contains 60% by mass or more, more preferably 80% by mass or more, still more preferably 90% by mass or more, even more preferably 95% by mass or more, and yet even more preferably 97% by mass or more of the thermoplastic resin in total. The upper limit is preferably 99.99% by mass or less, and more preferably 99.9% by mass or less. By setting such a range, the effects of the present embodiment tend to be more effectively exhibited. The resin composition of the present embodiment may contain only one type of thermoplastic resin or may contain two or more types of thermoplastic resins. When two or more types are contained, the total amount is preferably within the above range.

[0047] <Antibacterial agent (B)> The resin composition of the present embodiment contains an antibacterial agent. The antibacterial agent used in the present embodiment contains silver atoms and / or silver ions and one or more carriers selected from the group consisting of glass, calcium apatite, silica gel, calcium silicate, magnesium aluminum silicate, silica, alumina, and thiosulfite that carry the silver atoms and / or silver ions. The antibacterial agent used in the present embodiment contains silver atoms and / or silver ions. Usually, it is contained as silver ions in the antibacterial agent. By containing silver atoms and / or silver ions, the resulting resin composition has excellent antibacterial properties. It is preferable that the total of the silver atoms and / or silver ions occupies 0.01% by mass or more of the antibacterial agent, and it may occupy 0.1% by mass. The upper limit preferably occupies 5% by mass of the antibacterial agent, and it may occupy 3% by mass. Furthermore, the antibacterial agent used in this embodiment contains one or more carriers selected from the group consisting of glass, calcium apatite, silica gel, calcium silicate, magnesium aluminosilicate, silica, alumina, and thiosulfite, and preferably contains glass. In particular, it is presumed that by including such a carrier, the acidic groups on the surface of the antibacterial agent are reduced and / or the antibacterial agent does not act as a Lewis acid, so even if polyacetal resin is used as the thermoplastic resin, its decomposition is suppressed and the generation of formaldehyde is suppressed. Among these, the inclusion of glass is preferred because it effectively suppresses the generation of formaldehyde. Preferably, the total amount of the carrier and silver atoms and / or silver ions accounts for 60% by mass or more of the antibacterial agent, more preferably 70% by mass or more, even more preferably 80% by mass or more, and may be 90% by mass or more. Examples of commercially available products include Bactekiller from Fuji Chemical Co., Ltd., Million Guard from Koa Glass Co., Ltd., and Novalon from Toagosei Co., Ltd.

[0048] The antibacterial agent content in the resin composition of this embodiment is 0.05 parts by mass or more per 100 parts by mass of thermoplastic resin. The antibacterial agent content is more preferably 0.075 parts by mass or more, even more preferably 0.10 parts by mass or more, and even more preferably 0.15 parts by mass or more. The preferred amount is above the lower limit, which tends to further improve the antibacterial properties. The antibacterial agent content is also 3.00 parts by mass or less per 100 parts by mass of thermoplastic resin. It is more preferably 2.50 parts by mass or less, even more preferably 2.00 parts by mass or less, and even more preferably 1.00 part by mass or less. It is more preferable to keep it below the upper limit, as this suppresses the generation of formaldehyde. The resin composition of this embodiment may contain only one antibacterial agent or two or more. When two or more are included, it is preferable that the total amount is within the above range.

[0049] <Ionomer (C)> The resin composition of this embodiment contains an ionomer containing zinc ions and / or magnesium ions, and preferably contains zinc ions. Including such an ionomer effectively suppresses discoloration in a humid and hot environment. In particular, when polyacetal resin is used as the thermoplastic resin, the ionomer used in this embodiment is preferred because it contains zinc ions and / or magnesium ions, which prevents the generation of strong alkalis due to hydrolysis, suppresses the decomposition of the polyacetal resin, and reduces the amount of formaldehyde generated.

[0050] The ionomer used in this embodiment preferably contains an olefin-unsaturated carboxylic acid copolymer and zinc ions and / or magnesium ions. The above olefin is preferably an α-olefin. Examples include ethylene, propylene, and butene-1. Examples of the above unsaturated carboxylic acids include acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, maleic anhydride, itaconic anhydride, monomethyl maleate, and monoethyl maleate. Among these, it is preferable that at least one is selected from the group consisting of acrylic acid and methacrylic acid. These unsaturated carboxylic acids may be used individually or in combination of two or more. The above-mentioned olefin-unsaturated carboxylic acid copolymer may be not only a binary copolymer of an olefin and an unsaturated carboxylic acid, but also a polypolymer obtained by arbitrarily copolymerizing other monomers. When a polypolymer is included, it is preferable that the polypolymer is contained in 0 to 20 parts by mass per 100 parts by mass of the above-mentioned olefin-unsaturated carboxylic acid copolymer. Among these, copolymers of ethylene and acrylic acid and / or methacrylic acid are preferred.

[0051] The ionomer used in this embodiment preferably contains an ethylene copolymer with acrylic acid and / or methacrylic acid, and zinc ions and / or magnesium ions. In particular, it is preferable that it contains zinc ions. These ionomers are thought to capture formic acid produced by the oxidation of formaldehyde, thereby suppressing the decomposition of polyacetal resin. Furthermore, because they do not generate strong alkalis through hydrolysis, they tend to suppress the decomposition of polyacetal resin. Therefore, the amount of formaldehyde generated is thought to be suppressed. Furthermore, it is believed that the partial substitution of silver ions in the antibacterial agent with zinc and / or magnesium ions contained in the ionomer suppresses excessive elution of silver ions in a humid and hot environment, inhibiting reactions with surrounding basic substances, and thus suppressing discoloration in a humid and hot environment. As the ionomer mentioned above, commercially available products on the market may be used. Examples of such commercially available products include Hymiran 1557, Hymiran 1706, and Hymiran AM7329 from Mitsui Dow Polychemicals, and Surlyn 9945, Surlyn 9120, Surlyn 9150, Surlyn 6910, and Surlyn 6120 from Dow.

[0052] The ionomer content in the resin composition of this embodiment is 0.05 parts by mass or more, more preferably 0.075 parts by mass or more, even more preferably 0.10 parts by mass or more, and even more preferably 0.20 parts by mass or more, per 100 parts by mass of thermoplastic resin. Setting it above the lower limit effectively suppresses discoloration in a humid and hot environment. Furthermore, when polyacetal resin is used as the thermoplastic resin, the generation of formaldehyde can be effectively suppressed. In addition, the ionomer content is 3.00 parts by mass or less, more preferably 2.00 parts by mass or less, even more preferably 1.50 parts by mass or less, and even more preferably 0.80 parts by mass or less, per 100 parts by mass of thermoplastic resin. Setting it below the upper limit is more preferable because it can more effectively maintain antibacterial properties. The resin composition of this embodiment may contain only one ionomer or two or more ionomers. When two or more ionomers are included, it is preferable that the total amount is within the above range.

[0053] <Phosphorus compounds (D)> The resin composition of this embodiment contains a phosphorus compound containing trivalent phosphorus. Under humid and hot conditions, silver ions from the antibacterial agent contained in the resin composition tend to leach out. Excessive leaching of silver ions can cause discoloration due to the silver ions reacting with surrounding basic substances. The resin composition of this embodiment contains a phosphorus compound that appropriately coordinates silver ions, thereby suppressing the leaching of silver ions and maintaining antibacterial properties while suppressing discoloration under humid and hot conditions. Furthermore, when polyacetal resin is used as the thermoplastic resin, the inclusion of the above-mentioned phosphorus compound makes it less likely for acids and alkalis to be generated by hydrolysis, thereby suppressing the decomposition of the polyacetal resin and inhibiting the generation of formaldehyde, which is preferable.

[0054] The phosphorus compound used in this embodiment is not particularly limited as long as it contains trivalent phosphorus, but examples include trivalent phosphorus-containing compounds such as phosphorous acid, phosphine compounds, phosphonite compounds, and phosphite compounds. Among these, phosphine compounds are preferred, and triphenylphosphine is particularly preferred. The molecular weight of the phosphorus compound used in this embodiment is preferably 100 to 900.

[0055] The phosphine compound is not particularly limited, and any primary, secondary, or tertiary phosphine compound can be used, but tertiary phosphine compounds are particularly preferred, and tertiary aromatic phosphine compounds are more preferred.

[0056] Tertiary phosphine compounds are defined by the following formula R3P (In the formula, R represents an aliphatic hydrocarbon group or an aromatic hydrocarbon group which may have substituents, and the three Rs may be the same or different from one another.) It is represented as follows. A phenyl group is preferred for R. Substituents for R include alkyl groups such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, n-amyl group, isoamyl group, n-hexyl group, isohexyl group, cyclopentyl group, and cyclohexyl group, as well as alkoxy groups such as methoxy group and ethoxy group.

[0057] Specific examples of tertiary aromatic phosphine compounds include triphenylphosphine, tri-m-tolylphosphine, tri-o-tolylphosphine, tri-p-tolylphosphine, and tris-p-methoxyphenylphosphine. More specifically, the use of triphenylphosphine is preferred, but other phosphine compounds may be used in combination.

[0058] Preferably, the phosphite compound is of the following formula: R 2 OP(OR 3 )(OR 4 ) (In the formula, R 2 , R 3 and R 4 These are a hydrogen atom, an alkyl group with 1 to 30 carbon atoms, or an aryl group with 6 to 30 carbon atoms, and R 2 , R 3 and R 4 At least one of them is an aryl group with 6 to 30 carbon atoms. Examples of compounds represented by [the formula shown] are given.

[0059] Phosphite compounds include, for example, 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, tetraphenyldipropylene glycol diphosphite, tetraphenyltetra(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 Examples include lopyridene diphenyl 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, and bis(2,4-dicumylphenyl)pentaerythritol diphosphite. Among these, bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphite is preferred.

[0060] Preferably, the phosphonite compound is one of the following formulas: R 5 -P(OR 6 )(OR 7 ) (In the formula, R 5 , R 6 and R 7These are a hydrogen atom, an alkyl group with 1 to 30 carbon atoms, or an aryl group with 6 to 30 carbon atoms, and R 5 , R 6 and R 7 At least one of them is an aryl group with 6 to 30 carbon atoms. Examples of compounds represented by [the formula shown] are given.

[0061] Examples of phosphonite compounds include tetrakis(2,4-di-iso-propylphenyl)-4,4'-biphenylenediphosphonite, tetrakis(2,4-di-n-butylphenyl)-4,4'-biphenylenediphosphonite, tetrakis(2,4-di-tert-butylphenyl)-4,4'-biphenylenediphosphonite, tetrakis(2,4-di-tert-butylphenyl)-4,3'-biphenylenediphosphonite, and tetrakis(2,4-di-tert-butylphenyl)-3,3'-biphenylenediphosphonite. Examples include tetrakis(2,6-di-iso-propylphenyl)-4,4'-biphenylenediphosphonite, tetrakis(2,6-di-n-butylphenyl)-4,4'-biphenylenediphosphonite, tetrakis(2,6-di-tert-butylphenyl)-4,4'-biphenylenediphosphonite, tetrakis(2,6-di-tert-butylphenyl)-4,3'-biphenylenediphosphonite, and tetrakis(2,6-di-tert-butylphenyl)-3,3'-biphenylenediphosphonite.

[0062] The phosphorus compound content in the resin composition of this embodiment is 0.005 parts by mass or more, more preferably 0.0075 parts by mass or more, even more preferably 0.01 parts by mass or more, and even more preferably 0.015 parts by mass or more, per 100 parts by mass of thermoplastic resin. By setting the preferred amount above the lower limit, discoloration in a humid and hot environment is effectively suppressed. Furthermore, the phosphorus compound content is 1.00 parts by mass or less, more preferably 0.75 parts by mass or less, even more preferably 0.50 parts by mass or less, and even more preferably 0.10 parts by mass or less, per 100 parts by mass of thermoplastic resin. By setting the amount below the upper limit, antibacterial properties can be maintained more effectively. The resin composition of this embodiment may contain only one type of phosphorus compound, or it may contain two or more types. When it contains two or more types, it is preferable that the total amount is within the above range.

[0063] <Other ingredients> The resin composition of this embodiment may contain any conventionally known additives and fillers, as long as they do not impair the objectives of the present invention. Examples of additives and fillers used in this embodiment include ultraviolet absorbers, stabilizers other than the phosphorus compounds mentioned above, formaldehyde scavengers, antistatic agents, flame retardants, colorants, carbon fibers, glass fibers, glass flakes, potassium titanate whiskers, and the like.

[0064] The resin composition of this embodiment is formulated so that the total amount of the thermoplastic resin (A), the antibacterial agent (B), the ionomer (C), and the phosphorus compound (D), along with other components added as needed, is 100% by mass. In the resin composition of this embodiment, the total amount of the thermoplastic resin (A), the antibacterial agent (B), the ionomer (C), and the phosphorus compound (D) is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and even more preferably 99% by mass or more. The upper limit is 100% by mass.

[0065] In the resin composition of this embodiment, the mass ratio (C) / (B) of the antibacterial agent (B) to the ionomer (C) is preferably 0.4 or higher, and more preferably 15 or lower. Furthermore, the mass ratio (D) / (B) of the antibacterial agent (B) to the phosphorus compound (D) is preferably 0.005 or higher, and more preferably 5 or lower. By using this ratio, the effects of the present invention tend to be exhibited more effectively.

[0066] <Method for producing resin compositions> The method for producing the resin composition of this embodiment is not particularly limited and can be prepared by various conventional methods for preparing resin compositions. For example, (1) a method of mixing all the components constituting the resin composition, supplying it to an extruder and melt-kneading it to obtain a pelletized composition; (2) a method of supplying a portion of the components constituting the resin composition from the main feed port of an extruder and the remaining components from the side feed port and melt-kneading them to obtain a pelletized composition; (3) a method of preparing pellets with different compositions by extrusion or the like, and then mixing the pellets to adjust them to a predetermined composition; (4) a method of mixing a predetermined amount of blending components with thermoplastic resin pellets or pulverized material, or coating the surface of thermoplastic resin pellets or pulverized material with a predetermined amount of blending components to obtain a predetermined resin composition.

[0067] <Properties of resin compositions> The resin composition of this embodiment exhibits excellent antibacterial properties. Specifically, it is preferable that the antibacterial activity value calculated by the following formula (1) when a molded article formed from the resin composition is subjected to an antibacterial test in accordance with JIS Z 2801 is 2.0 or higher. There is no particular upper limit for the antibacterial activity value, but 20.0 or less is practical. Formula (1) Antibacterial activity value = log(unprocessed sample 1 cm) 2 (Number of viable bacteria after culture) - log(processed sample 1 cm) 2 (Number of viable bacteria per culture) The antibacterial properties are measured according to the examples described below.

[0068] The resin composition of this embodiment suppresses discoloration in a humid and hot environment. Specifically, when a dumbbell test piece is molded using the resin composition in accordance with ISO 527, and the test piece is left standing for 500 hours at a temperature of 60°C and a humidity of 95%, the color difference ΔE before and after is preferably 3.9 or less, more preferably 3.5 or less, even more preferably 2.5 or less, and even more preferably 2.0 or less. The lower limit of the color difference ΔE is ideally 0, but 0.01 or more is realistic. Discoloration under humid and hot conditions is measured according to the examples described below.

[0069] The resin composition of this embodiment suppresses formaldehyde generation even when polyacetal resin is used as the thermoplastic resin. Specifically, the amount of formaldehyde generated from a flat test piece measuring 100 mm in length, 40 mm in width, and 2 mm in thickness, formed from the resin composition, is preferably less than 10 ppm, more preferably less than 8 ppm, and even more preferably less than 7 ppm, as measured in accordance with VDA275. The lower limit of the amount of formaldehyde generated is ideally 0 ppm, but 0.1 ppm or higher is practical. The amount of formaldehyde emitted is measured according to the example described below.

[0070] <Molded articles of resin compositions> This embodiment also includes molded articles formed from the resin composition of this embodiment. The pellets obtained by pelletizing the resin composition of this embodiment can be molded into molded bodies using various molding methods. Alternatively, the resin composition, which is melt-kneaded in an extruder, can be directly molded into molded bodies without going through the pellet stage. There are no particular restrictions on the shape of the molded body, and it can be appropriately selected according to the application and purpose of the molded body. Examples include plate-shaped, rod-shaped, sheet-shaped, film-shaped, cylindrical, annular, circular, elliptical, gear-shaped, polygonal, irregularly shaped, hollow, frame-shaped, box-shaped, panel-shaped, and cap-shaped molded bodies. The molded body in this embodiment may be a finished product, a part, or welded parts.

[0071] The method for forming the molded article is not particularly limited, and conventionally known molding methods can be employed. Examples include injection molding, injection compression molding, extrusion molding, shape extrusion, transfer molding, hollow molding, gas-assisted hollow molding, blow molding, extrusion blow molding, IMC (in-mold coating) molding, rotational molding, multilayer molding, two-color molding, insert molding, sandwich molding, foam molding, and pressure molding.

[0072] <Application> The resin composition of this embodiment and the molded articles formed from the resin composition are preferably used in applications where antibacterial properties are required. For example, it is suitable for food processing, plumbing, medical, and hygiene applications. Specifically, examples include food transport belts, bathtub components, toilet components, inhalers, and insulin pens. [Examples]

[0073] The present invention will be described in more detail below with reference to examples. The materials, amounts used, proportions, processing content, and processing procedures shown in the following examples can be modified as appropriate, as long as they do not depart 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 other reasons, measurements can be taken using other instruments with equivalent performance.

[0074] 1.Raw materials Polyacetal resin (A) (POM): An acetal copolymer obtained by copolymerizing trioxane and 1,3-dioxolane such that the 1,3-dioxolane content in the POM is 3.8% by mass (4.6 mol%), with a melt index (ASTM-D1238 standard: 190°C, 2.16 kg) of 10.5 g / 10 min and a melting point of 165°C.

[0075] Antimicrobial agent (B): (B1) Silver-supported glass, manufactured by Fuji Chemical Co., Ltd., product name "Bactekiller BM-102SD" (B2) Silver-supported zeolite, manufactured by Zeomic Corporation, product name "Sinanen Zeomic KM10D"

[0076] Ionomer (C): (C1) Ionomer of ethylene-methacrylic acid copolymer containing zinc ions, manufactured by Mitsui Dow Polychemicals, product name "Hymiran 1554W" (C2) Ionomer of ethylene-methacrylic acid copolymer containing zinc ions, manufactured by Mitsui Dow Polychemicals, trade name "Hymiran 1706"

[0077] Phosphorus compound (D): Triphenylphosphine, manufactured by BASF.

[0078] 2. Examples 1-6, Comparative Examples 1-9 <Compound> Polyacetal resin (A), antibacterial agent (B), ionomer (C), and phosphorus compound (D) were uniformly mixed in the proportions (parts by mass) shown in Tables 1 and 2 using a tumbler manufactured by Seiwa Iron Works Co., Ltd. Then, the mixture was melt-kneaded using a twin-screw extruder (manufactured by Ikegai Co., Ltd., PCM-30, screw diameter 30 mm) under conditions of screw rotation speed of 120 rpm and cylinder setting temperature of 190°C, extruded into strands, and cut with a pelletizer to produce resin compositions (pellets).

[0079] <Antibacterial> Antibacterial properties were tested using a flat test piece measuring 50 mm in length, 50 mm in width, and 2 mm in thickness, in accordance with JIS Z 2801. The resin composition (pellets) obtained above was used to form flat test specimens measuring 63 mm in length, 63 mm in width, and 2 mm in thickness using an injection molding machine (Nissei Plastic Industrial Co., Ltd., DCE140) under conditions of a resin temperature of 240°C and a mold temperature of 80°C. Subsequently, test specimens measuring 50 mm in length, 50 mm in width, and 2 mm in thickness were prepared by processing them with a diamond cutting machine. Next, using the flat test pieces obtained above, an antibacterial test was conducted in accordance with JIS Z 2801. A test specimen (50 mm long x 50 mm wide x 2 mm thick) was placed in a petri dish, 0.4 mL of a test bacterial suspension of E. coli or Staphylococcus epidermidis was dropped onto it, a film (40 mm x 40 mm) was placed over it, and the petri dish was then covered with a lid. The petri dish was incubated at 35°C and under 90% RH or higher for 24 hours. Subsequently, 10 mL of lecithin sorbate 80-added soybean casein digest agar (SCDLP) medium was added, the test bacteria were washed from the film and test specimen, and the number of bacteria in the solution was measured by the agar plate culture method. The antibacterial activity value was calculated according to the following formula (1). Formula (1) Antibacterial activity value = log(unprocessed sample 1 cm) 2 (Number of viable bacteria after culture) - log(processed sample 1 cm) 2 (Number of viable bacteria per culture) Antimicrobial activity value ≥ 2.0: + Antimicrobial properties present Antimicrobial activity value < 2.0: No antimicrobial properties That was their assessment.

[0080] <Degree of discoloration after moist heat treatment> The resin composition (pellets) obtained above was used to form dumbbell test specimens in accordance with ISO 527 using an injection molding machine (Shibaura Machine Co., Ltd., EC100SX-2A) under conditions of a resin temperature of 190°C and a mold temperature of 90°C. The color tone was then measured using a Nippon Denshoku Industries SE6000 (light source: C / 2, reflected light). Next, the dumbbell test specimens were left to stand for 500 hours under conditions of 60°C and 95% humidity using a constant temperature and humidity test chamber (ESPEC Corporation). The color tone was then measured again using the method described above, and the color difference ΔE before and after the moist heat treatment was calculated.

[0081] <Formaldehyde emissions> Formaldehyde emissions were measured in accordance with VDA275. The resin composition (pellets) obtained above was used to form flat test pieces measuring 100 mm in length, 40 mm in width, and 2 mm in thickness using an injection molding machine SE30DUZ (manufactured by Sumitomo Heavy Industries, Ltd.) under conditions of a resin temperature of 190°C and a mold temperature of 80°C. Subsequently, 50 mL of distilled water was placed in a 1 L PE container, one test piece was suspended from a wire, the polyethylene container was sealed with a lid, and the container was left in a 60°C oven for 3 hours. After that, it was left at room temperature for 60 minutes, and the absorbent solution was collected and analyzed by the acetylacetone colorimetric method.

[0082] [Table 1]

[0083] [Table 2]

[0084] As is clear from the results above, the molded articles obtained from the resin compositions of this embodiment (Examples 1-6) exhibited excellent antibacterial properties and suppressed discoloration in humid and hot environments. Furthermore, the generation of formaldehyde, which is a problem with polyacetal resins, was also suppressed. In contrast, when a different antibacterial agent was included than that of this embodiment (Comparative Examples 7-9), the degree of discoloration in a humid and hot environment was greater. When the ionomer was not included (Comparative Examples 2, 4-6), the degree of discoloration in a humid and hot environment was also greater. Furthermore, the generation of formaldehyde, which is a problem in polyacetal resins, increased. On the other hand, when the ionomer content was too high (Comparative Example 3), the antibacterial properties deteriorated. When the stabilizer was not included (Comparative Example 1), the degree of discoloration in a humid and hot environment was greater.

Claims

1. Per 100 parts by mass of thermoplastic resin (A), Antibacterial agent (B) 0.075 to 3.00 parts by mass, 0.05 to 3.00 parts by mass of ionomer (C) containing zinc ions, 0.005 to 1.00 parts by mass of tertiary aromatic phosphine (D) and Includes, The antibacterial agent (B) comprises a silver atom and / or silver ion, and one or more carriers selected from the group consisting of glass, calcium apatite, silica gel, calcium silicate, magnesium aluminosilicate, silica, alumina, and thiosulfite, on which the silver atom and / or silver ion is supported. The thermoplastic resin includes a polyacetal resin. A resin composition, A resin composition in which a dumbbell test piece is molded using the resin composition in accordance with ISO 527, and the color difference ΔE before and after the test piece is left standing for 500 hours under conditions of a temperature of 60°C and a humidity of 95% is 3.9 or less.

2. A dumbbell test specimen was molded using the aforementioned resin composition in accordance with ISO 527, and the color difference ΔE before and after the test specimen was left standing for 500 hours under conditions of 60°C and 95% humidity was 3.5 or less. A flat test piece measuring 100 mm in length, 40 mm in width, and 2 mm in thickness, formed from the aforementioned resin composition, showed a formaldehyde emission level of less than 10 ppm, as measured in accordance with VDA275. An antimicrobial test was performed in accordance with JIS Z 2801 using a flat test piece measuring 50 mm in length, 50 mm in width, and 2 mm in thickness, formed from the resin composition, by dropping 0.4 mL of a test bacterial solution of Escherichia coli onto the test piece, covering it with a film (40 mm x 40 mm), then covering the petri dish with a lid, and culturing the petri dish at 35°C and in an environment of 90% RH or higher for 24 hours. After that, 10 mL of lecithin sorbate 80-added soybean casein digest agar (SCDLP) medium was added, the test bacteria were washed out from the film and test piece, the number of bacteria in the solution was measured by the agar plate culture method, and the antimicrobial activity value calculated according to the following formula (1) was 2.0 or higher, according to the resin composition according to claim 1. Formula (1) Antimicrobial activity value = log (unprocessed sample 1 cm) ２ (Number of viable bacteria per unit area after culture) - log (processed sample 1 cm) ２ (Number of viable bacteria per culture)

3. The resin composition according to claim 1 or 2, wherein the support body includes glass.

4. The resin composition according to any one of claims 1 to 3, wherein the tertiary aromatic phosphine (D) comprises triphenylphosphine.

5. A molded article formed from the resin composition according to any one of claims 1 to 4.

Images