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) and 0.005 to 1.00 pt.mass of a phosphorus compound containing trivalent phosphorus (C) based on 100 pts.mass of a thermoplastic resin including at least one of a polyacetal resin, a polyamide resin, a polyester resin and a polyphenylene ether resin, wherein the antibacterial agent (B) contains silver atoms and / or silver ions and the mass ratio, (C) / (B) between the phosphorus compound containing trivalent phosphorus (C) and the antibacterial agent (B) is 0.02 to 5.00.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 incorporating a specific antibacterial agent and stabilizer into a thermoplastic resin. Specifically, the above problem was solved by the following means. <1> A resin composition comprising 100 parts by mass of a thermoplastic resin (A) containing at least one of polyacetal resin, polyamide resin, polyester resin, and polyphenylene ether resin, 0.05 to 3.00 parts by mass of an antimicrobial agent (B), and 0.005 to 1.00 parts by mass of a phosphorus compound (C) containing trivalent phosphorus, wherein the antimicrobial agent (B) contains silver atoms and / or silver ions, and the mass ratio of the phosphorus compound (C) containing trivalent phosphorus to the antimicrobial agent (B), (C) / (B), is 0.02 to 5.00. <2> The thermoplastic resin (A) includes a polyacetal resin. <1> The resin composition described above. <3> The antimicrobial agent (B) comprises one or more carriers selected from the group consisting of glass, calcium apatite, silica gel, calcium silicate, magnesium aluminosilicate, silica, alumina, and thiosulfite. <1> or <2> The resin composition described above. <4> The aforementioned carrier includes glass, <3> The resin composition described above. <5> The phosphorus compound (C) comprises triphenylphosphine. <1> ~ <4> A resin composition as described in any one of the following. <6> <1> ~ <5> 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] The following describes in detail embodiments for carrying out the present invention (hereinafter simply referred to as "this embodiment"). Note that the following embodiment is illustrative for explaining the present invention, and the present invention is not limited to this embodiment. In this specification, "~" is used to mean that the numbers before and after it are included as the lower and upper limits, respectively. In this specification, unless otherwise specified, all kinds of physical property values and characteristic values are those at 23°C. When the measurement methods and the like described by the standards shown in this specification differ from year to year, unless otherwise specified, they shall be based on the standards as of January 1, 2021.

[0009] The resin composition of this embodiment contains, per 100 parts by mass of a thermoplastic resin (A) containing at least one of a polyacetal resin, a polyamide resin, a polyester resin, and a polyphenylene ether resin, 0.05 to 3.00 parts by mass of an antibacterial agent (B) and 0.005 to 1.00 parts by mass of a phosphorus compound (C) containing trivalent phosphorus. The antibacterial agent (B) contains silver atoms and / or silver ions, and the mass ratio of the phosphorus compound (C) containing trivalent phosphorus to the antibacterial agent (B), (C) / (B), is 0.02 to 5.00. By adopting such a configuration, a resin composition excellent in antibacterial property and suppressed in discoloration under a wet and hot environment can be obtained. When an antibacterial agent containing silver atoms and / or silver ions is blended with the thermoplastic resin (A), silver ions of the antibacterial agent contained in the resin composition elute under a wet and hot environment. Excessive elution of silver ions is considered to cause discoloration when the silver ions react with surrounding basic substances. In the resin composition of this embodiment, it is presumed that the phosphorus compound (C) containing trivalent phosphorus coordinates silver ions moderately to suppress the elution of silver ions and suppress discoloration under a wet and hot environment while maintaining antibacterial property.

[0010] <Thermoplastic resin (A)> The resin composition of this embodiment contains a thermoplastic resin (A). The thermoplastic resin (A) used in this embodiment contains at least one of a polyacetal resin, a polyamide resin, a polyester resin, and a polyphenylene ether resin. It is more preferable to contain at least one of a polyacetal resin, a polyamide resin, and a polyester resin, and it is even more preferable to contain a polyacetal resin.

[0011] <<Polyacetal resin>> The resin composition of this embodiment preferably contains a polyacetal resin. The polyacetal resin used in this embodiment is not particularly limited, and it may be a homopolymer containing only a divalent oxymethylene group as a structural unit, or a copolymer containing a divalent oxymethylene group and a divalent oxyalkylene group having 2 to 6 carbon atoms as structural units.

[0012] Examples of the oxyalkylene group having 2 to 6 carbon atoms include an oxyethylene group, an oxypropylene group, and an oxybutylene group.

[0013] In the polyacetal resin, the ratio of the divalent oxyalkylene group having 2 to 6 carbon atoms to the total number of moles of the oxymethylene group and the divalent oxyalkylene group having 2 to 6 carbon atoms is not particularly limited, and it may be 0.5 to 10 mol%.

[0014] To produce the above polyacetal resin, trioxane is usually used as the main raw material. In addition, to introduce a divalent oxyalkylene group having 2 to 6 carbon atoms into the polyacetal resin, a cyclic formal or a cyclic ether can be used. Specific examples of the cyclic formal include 1,3-dioxolane, 1,3-dioxane, 1,3-dioxepane, 1,3-dioxocane, 1,3,5-trioxepane, 1,3,6-trioxocane, etc., and specific examples of the cyclic ether include ethylene oxide, propylene oxide, and butylene oxide. To introduce an oxyethylene group into the polyacetal resin, 1,3-dioxolane may be used as the main raw material. To introduce an oxypropylene group, 1,3-dioxane may be used as the main raw material. To introduce an oxybutylene group, 1,3-dioxepane may be used as the main raw material. In the polyacetal resin, it is preferable that the amount of hemi-formal end groups, the amount of formyl end groups, and the amount of end groups unstable to heat, acids, and bases are small. Here, the hemi-formal end group is represented by -OCH2OH, and the formyl end group is represented by -CHO.

[0015] 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.

[0016] 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.

[0017] <<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.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] <<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.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] <<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.

[0032] [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.)

[0033] R a and R bAs 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 the group 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] The resin composition of this embodiment preferably contains a total of 60% by mass or more of thermoplastic resin (A), more preferably 80% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, and even more preferably 97% by mass or more. The upper limit is preferably 99.99% by mass or less, and more preferably 99.9% by mass or less. By setting the limit within this range, the effects of this embodiment tend to be more effectively exhibited. The resin composition of this embodiment may contain only one type of thermoplastic resin (A), 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.

[0039] <Antibacterial agent (B)> The resin composition of this embodiment contains an antibacterial agent (B). The antibacterial agent (B) used in this embodiment contains silver atoms and / or silver ions. Typically, silver ions are present in the antibacterial agent (B). The inclusion of silver atoms and / or silver ions results in a resin composition with excellent antibacterial properties. In this embodiment, the total amount of silver atoms and / or silver ions in the antibacterial agent (B) is preferably 0.01% by mass or more of the antibacterial agent (B), and may be 0.1% by mass. The upper limit is preferably 5% by mass of the antibacterial agent (B), and may be 3% by mass. Furthermore, the antibacterial agent (B) used in this embodiment preferably has silver atoms and / or silver ions supported on a carrier. The antibacterial agent (B) used in this embodiment preferably 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 more preferably contains glass. 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 (B), 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.

[0040] The content of the antibacterial agent (B) in the resin composition of this embodiment is 0.05 parts by mass or more per 100 parts by mass of thermoplastic resin (A). The content of the antibacterial agent (B) 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 content of the antibacterial agent (B) is also 3.00 parts by mass or less per 100 parts by mass of thermoplastic resin (A), more preferably 2.50 parts by mass or less, even more preferably 2.00 parts by mass or less, even more preferably 1.00 part by mass or less, and may also be 0.70 parts by mass or less. It is more preferable to set the amount below the upper limit because it suppresses discoloration in a humid and hot environment. The resin composition of this embodiment may contain only one type of antibacterial agent (B), 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.

[0041] <Phosphorus compounds (C)> The resin composition of this embodiment contains a phosphorus compound (C) containing trivalent phosphorus. Under humid and hot conditions, silver ions from the antibacterial agent (B) 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 (C) that appropriately coordinates silver ions, thereby suppressing the leaching of silver ions and maintaining antibacterial properties while suppressing discoloration under humid and hot conditions. The phosphorus compound (C) 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 (C) used in this embodiment is preferably 100 to 900.

[0042] The phosphine compound is not particularly limited, and any of primary, secondary, and tertiary phosphine compounds can be used. However, tertiary phosphine compounds are particularly preferred, and more preferably tertiary aromatic phosphine compounds.

[0043] The tertiary phosphine compound is represented by the following formula R3P (wherein, R represents an aliphatic hydrocarbon group or an aromatic hydrocarbon group which may have a substituent, and the three Rs may be the same or different from each other). R is preferably a phenyl group. Examples of the substituent of 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, cyclohexyl group, and alkoxy groups such as methoxy group, ethoxy group, etc.

[0044] Specific examples of the tertiary aromatic phosphine compound include triphenylphosphine, tri-m-tolylphosphine, tri-o-tolylphosphine, tri-p-tolylphosphine, tris-p-methoxyphenylphosphine, etc. More specifically, the use of triphenylphosphine is preferred, but other phosphine compounds may be used in combination.

[0045] As the phosphite compound, preferably, the following formula: R 2 O-P(OR 3 )(OR 4 ) (wherein, 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 at least one of R 2 , R 3 and R 4 is an aryl group having 6 to 30 carbon atoms). The compounds represented by this are exemplified.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] The content of the phosphorus compound (C) 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 (A). By setting the preferred amount above the lower limit, discoloration in a humid and hot environment is effectively suppressed. Furthermore, the content of the phosphorus compound (C) 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, even more preferably 0.30 parts by mass or less, and even more preferably 0.20 parts by mass or less, per 100 parts by mass of thermoplastic resin (A). 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 (C), 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.

[0050] In the resin composition of this embodiment, the mass ratio (C) / (B) of the phosphorus compound (C) containing the trivalent phosphorus to the antibacterial agent (B) is 0.02 to 5.00. Setting it above the lower limit allows for more effective suppression of discoloration after moist heat. Setting it below the upper limit tends to further improve antibacterial properties. The (C) / (B) ratio is preferably 0.08 or higher, more preferably 0.10 or higher, even more preferably 0.18 or higher, even more preferably 0.25 or higher, and even more preferably 0.35 or higher. The (C) / (B) ratio is also preferably 4.00 or lower, more preferably 3.00 or lower, even more preferably 2.00 or lower, even more preferably 1.00 or lower, and even more preferably 0.60 or lower.

[0051] <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 resins other than the thermoplastic resin (A), ultraviolet absorbers, heat stabilizers other than the phosphorus compound (C), light stabilizers, formaldehyde scavengers, antistatic agents, flame retardants, colorants, carbon fibers, glass fibers, glass flakes, potassium titanate whiskers, and the like.

[0052] The resin composition of this embodiment is formulated so that the total amount of the thermoplastic resin (A), the antibacterial agent (B), and the phosphorus compound (C), 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), and the phosphorus compound (C) 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. The resin composition of this embodiment preferably contains substantially no heat stabilizers other than the phosphorus compound (C). Substantially containing no heat stabilizers means, for example, that the content of heat stabilizers other than the phosphorus compound (C) in the resin composition is 10% by mass or less of the content of the phosphorus compound (C) in the resin composition, preferably 5% by mass or less, more preferably 3% by mass or less, and even more preferably 1% by mass or less.

[0053] <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 pellets or pulverized material of thermoplastic resin (A), or coating the surface of pellets or pulverized material of thermoplastic resin (A) with a predetermined amount of blending components to obtain a predetermined resin composition.

[0054] <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.

[0055] The resin composition of this embodiment suppresses discoloration in a humid and hot environment. Specifically, when a dumbbell test piece conforming to ISO 527 is molded using the resin composition, 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 10.0 or less, more preferably 7.0 or less, even more preferably 5.0 or less, even more preferably 3.0 or less, and even more preferably 2.5 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.

[0056] <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.

[0057] 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.

[0058] <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]

[0059] 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.

[0060] 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.

[0061] Antibacterial agent (B): Silver-supported glass, manufactured by Fuji Chemical Co., Ltd., product name "Bactekiller BM-102SD"

[0062] Phosphorus compound (C1): Triphenylphosphine, manufactured by BASF. [ka] Comparative stabilizer (C2): Tinuvin 765, manufactured by BASF. [ka]

[0063] 2. Examples 1-10, Comparative Examples 1-6 <Compound> Polyacetal resin (A), an antibacterial agent (B), and a phosphorus compound (C) or a comparative stabilizer (C2) were uniformly mixed in the proportions (parts by mass) shown in Tables 1 to 3 using a tumbler manufactured by Seiwa Iron Works Co., Ltd. Then, the mixture was melt-kneaded using a twin-screw extruder (Ikegai Co., Ltd., PCM-30, screw diameter 30 mm) under conditions of a screw rotation speed of 120 rpm and a cylinder setting temperature of 190°C, extruded into strands, and cut with a pelletizer to produce resin compositions (pellets).

[0064] <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.

[0065] <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.

[0066] [Table 1]

[0067] [Table 2]

[0068] [Table 3]

[0069] As is clear from the results above, the molded articles obtained from the resin compositions of this embodiment (Examples 1 to 10) exhibited excellent antibacterial properties and suppressed discoloration in a humid and hot environment. In contrast, when the phosphorus compound (C) containing trivalent phosphorus was not included (Comparative Examples 1-2), the degree of discoloration in a humid and hot environment increased. When the amount of phosphorus compound (C) was too low relative to the antibacterial agent (B) (Comparative Example 3), the degree of discoloration in a humid and hot environment increased. Furthermore, when a heat stabilizer other than the phosphorus compound (C) containing trivalent phosphorus was included (Comparative Examples 4-6), the degree of discoloration in a humid and hot environment increased.

Claims

1. A thermoplastic resin (A) containing polyacetal resin, Antibacterial agent (B) 0.05 to 3.00 parts by mass, 0.005 to 1.00 parts by mass of a phosphorus compound (C) containing trivalent phosphorus and Includes, The antibacterial agent (B) comprises silver atoms and / or silver ions, The mass ratio of the phosphorus compound (C) containing trivalent phosphorus to the antibacterial agent (B), (C) / (B), is between 0.02 and 5.

00. The antibacterial agent (B) comprises one or more carriers selected from the group consisting of glass, calcium apatite, silica gel, calcium silicate, magnesium aluminosilicate, silica, alumina, and thiosulfite. The phosphorus compound (C) containing trivalent phosphorus is a tertiary aromatic phosphine compound. A resin composition, The aforementioned resin composition is a resin composition containing 80% by mass or more of polyacetal resin.

2. The resin composition according to claim 1, wherein the molecular weight of the phosphorus compound (C) containing trivalent phosphorus is 100 to 900.

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 phosphorus compound (C) containing trivalent phosphorus contains triphenylphosphine.

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

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