Thermoplastic resin composition

Abstract

To provide a thermoplastic resin composition which has antimicrobial properties and is suitable for a disinfection method by wiping with a disinfectant solution and deep ultraviolet rays (UV-C).SOLUTION: There is provided a thermoplastic resin composition which comprises: a graft copolymer (A) obtained by graft polymerizing a monomer mixture (C) containing an aromatic alkenyl compound and a vinyl cyanide compound in the presence of a composite rubber (G) consisting of a polyorganosiloxane and a polyalkyl acrylate; a polymethyl methacrylate-based resin (M); and an antibacterial agent (K).SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a thermoplastic resin composition. More specifically, the present invention relates to a thermoplastic resin composition having antibacterial properties and suitable for wiping with a disinfectant solution and sterilization by deep ultraviolet (UV-C).

Background Art

[0002] In recent years, the global spread of the novel coronavirus has become a problem, which has become a major hindrance to social and economic activities. In particular, restaurants, various event venues, transportation facilities, etc. where people gather have been greatly affected economically.

[0003] As a method for suppressing infection with the novel coronavirus (COVID-19), disinfection and sterilization by a disinfectant solution or deep ultraviolet (UV-C) irradiation are performed (Patent Document 1).

[0004] Devices for performing these methods are exposed to a disinfectant solution or deep ultraviolet (UV-C) during use. Furthermore, since it is also conceivable that it adheres to the device itself, wiping with a disinfectant solution and sterilization / disinfection by deep ultraviolet (UV-C) irradiation are performed on the device for sterilization / disinfection. Therefore, the resin parts constituting these devices cause deterioration such as embrittlement due to chemical stress cracks by the disinfectant solution and discoloration by UV-C.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] The present invention solves the problems of the prior art described above, and the object of the present invention is to provide a thermoplastic resin composition that has antibacterial properties and is suitable for wiping with disinfectant solutions and sterilization by deep ultraviolet (UV-C) light. [Means for solving the problem]

[0007] The inventors of the present invention conducted extensive research to solve the above problems and found that a thermoplastic resin composition comprising a graft copolymer (A) obtained by graft polymerizing a monomer mixture (C) containing an aromatic alkenyl compound and a vinyl cyanide compound in the presence of a specific composite rubber (G), a polymethyl methacrylate resin (M), and an antibacterial agent (K) can solve the above problems, thus completing the present invention. In other words, the gist of this invention is as follows:

[0008] [1] A thermoplastic resin composition comprising a graft copolymer (A) obtained by graft polymerizing a monomer mixture (C) containing an aromatic alkenyl compound and a vinyl cyanide compound in the presence of a composite rubber (G) consisting of a polyorganosiloxane and a polyalkyl acrylate, a polymethyl methacrylate resin (M), and an antimicrobial agent (K).

[0009] [2] The thermoplastic resin composition according to [1], wherein the composite rubber (G) contains 1 to 25% by mass of polyorganosiloxane, contains 75 to 99% by mass of polyalkyl acrylate, and the volume average particle size of the composite rubber (G) is 0.08 to 0.16 μm.

[0010] [3] The thermoplastic resin composition according to [1] or [2], wherein the monomer mixture (C) comprises 65 to 85% by mass of an aromatic alkenyl compound, 15 to 35% by mass of a vinyl cyanide compound, and 0 to 15% by mass of other vinyl monomers copolymerizable with these (provided that the total of these amounts is 100% by mass), and the amount of the monomer mixture (C) used for graft copolymerization is 80 to 140 parts by mass per 100 parts by mass of the composite rubber (G).

[0011] [4] A thermoplastic resin composition according to any one of [1] to [3], comprising 90 to 20 parts by mass of the graft copolymer (A) and 10 to 80 parts by mass of the polymethyl methacrylate resin (M) in total of 100 parts by mass of the graft copolymer (A) and the polymethyl methacrylate resin (M).

[0012] [5] The thermoplastic resin composition according to any one of [1] to [4], comprising 0.1 to 10 parts by mass of the antibacterial agent (K) with respect to 100 parts by mass of the graft copolymer (A) and the polymethyl methacrylate resin (M) in total.

[0013] [6] A thermoplastic resin composition according to any one of [1] to [5], comprising 3 to 7% by mass of polyorganosiloxane in 100% by mass of the thermoplastic resin composition.

[0014] [7] A molded article obtained by molding any of the thermoplastic resin compositions described in [1] to [6]. [Effects of the Invention]

[0015] The thermoplastic resin composition of the present invention has antibacterial properties and does not suffer from defects such as embrittlement or discoloration even when wiped with disinfectant or sterilized with deep ultraviolet (UV-C) light. Therefore, the thermoplastic resin composition and molded articles of the present invention are useful as components of sterilization and disinfection devices that are exposed to disinfectants and UV-C during use, and are subjected to wiping with disinfectants and sterilization / disinfection by UV-C irradiation, as well as as resin products that are subjected to wiping with disinfectants and sterilization / disinfection by UV-C irradiation. [Modes for carrying out the invention]

[0016] The embodiments of the present invention will be described in detail below, but these descriptions are merely examples (representative examples) of embodiments of the present invention, and the present invention is not limited to these contents unless it exceeds the gist of the invention.

[0017] [Thermoplastic resin composition] The thermoplastic resin composition of the present invention is characterized by containing a graft copolymer (A) obtained by graft-polymerizing a monomer mixture (C) containing an aromatic alkenyl compound and a vinyl cyanide compound in the presence of a composite rubber (G) composed of a polyorganosiloxane and a polyalkyl acrylate, a polymethyl methacrylate-based resin (M), and an antibacterial agent (K).

[0018] [Composite rubber (G)] The composite rubber (G) used in the present invention is composed of a polyorganosiloxane and a polyalkyl acrylate.

[0019] [Polyorganosiloxane] The polyorganosiloxane constituting the composite rubber (G) is not particularly limited, but preferably a polyorganosiloxane containing a vinyl polymerizable functional group. More preferably, it is composed of 0.3 to 3 mol% of a vinyl polymerizable functional group-containing siloxane unit and 97 to 99.7 mol% of a dimethylsiloxane unit, and further, a silicon atom having three or more siloxane bonds is 1 mol% or less with respect to all silicon atoms in the polydimethylsiloxane.

[0020] When the content of the vinyl polymerizable functional group-containing siloxane unit in the above polyorganosiloxane is less than 0.3 mol%, the complexation with the polyalkyl acrylate becomes insufficient, and the surface appearance of the obtained molded product deteriorates. Also, when the content of the vinyl polymerizable functional group-containing siloxane unit in the polyorganosiloxane exceeds 3 mol%, or when the silicon atom having three or more siloxane bonds exceeds 1 mol% with respect to all silicon atoms in the polyorganosiloxane, the impact resistance of the thermoplastic resin composition tends to be low. Considering both the impact resistance and the molding appearance of the thermoplastic resin composition, the content of the vinyl polymerizable functional group-containing siloxane unit in the polyorganosiloxane is preferably 0.5 to 2 mol%, particularly 0.5 to 1 mol%.

[0021] The production method of the above polyorganosiloxane is not particularly limited, but it is preferably produced by emulsion polymerization. For example, a latex obtained by emulsifying a mixture composed of dimethylsiloxane and a vinyl-polymerizable functional group-containing siloxane, or a siloxane mixture further containing a siloxane-based crosslinking agent as required, with an emulsifier and water, is atomized using a homomixer that atomizes it with a shearing force generated by high-speed rotation, a homogenizer that atomizes it with the jet output of a high-pressure generator, etc. After atomization, it is polymerized at a high temperature using an acid catalyst, and then the acid is neutralized with an alkaline substance.

[0022] As the method for adding the acid catalyst used in the polymerization, there are a method of mixing it together with the siloxane mixture, emulsifier, and water, a method of dropping the latex in which the siloxane mixture is atomized into a hot acid aqueous solution at a constant rate, etc. Considering the ease of controlling the particle size of the resulting polyorganosiloxane, the method of dropping the latex in which the siloxane mixture is atomized into a hot acid aqueous solution at a constant rate is preferred.

[0023] Examples of the dimethylsiloxane used in the production of polyorganosiloxane include dimethylsiloxane-based cyclic bodies having a ring size of 3 or more members, and those having a ring size of 3 to 7 members are preferred. Specifically, hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, dodecamethylcyclohexasiloxane, etc. can be mentioned. These can be used alone or in combination of two or more.

[0024] Furthermore, vinyl polymerizable functional group-containing siloxanes are those that contain vinyl polymerizable functional groups and can be bonded to dimethylsiloxane via siloxane bonds. Considering the reactivity with dimethylsiloxane, various alkoxysilane compounds containing vinyl polymerizable functional groups are preferred as vinyl polymerizable functional group-containing siloxanes. Specifically, examples include methacryloyloxysiloxanes such as β-methacryloyloxyethyl dimethoxymethylsilane, γ-methacryloyloxypropyl dimethoxymethylsilane, γ-methacryloyloxypropyl methoxydimethylsilane, γ-methacryloyloxypropyl trimethoxysilane, γ-methacryloyloxypropyl ethoxydiethylsilane, γ-methacryloyloxypropyl diethoxymethylsilane, and δ-methacryloyloxybutyl diethoxymethylsilane; vinylsiloxanes such as tetramethyltetravinylcyclotetrasiloxane; p-vinylphenyl dimethoxymethylsilane; and mercaptosiloxanes such as γ-mercaptopropyl dimethoxymethylsilane and γ-mercaptopropyl trimethoxysilane. These vinyl polymerizable functional group-containing siloxanes can be used individually or as a mixture of two or more.

[0025] Siloxane-based crosslinking agents include trifunctional or tetrafunctional silane-based crosslinking agents such as trimethoxymethylsilane, triethoxyphenylsilane, tetramethoxysilane, tetraethoxysilane, and tetrabutoxysilane. These are used individually or in combination of two or more.

[0026] Furthermore, anionic emulsifiers are preferred as emulsifiers used in the production of polyorganosiloxane according to the present invention, and emulsifiers selected from among sodium alkylbenzenesulfonate and sodium polyoxyethylene nonylphenyl ether sulfate are used. Sulfonic acid-based emulsifiers such as sodium alkylbenzenesulfonate and sodium laurylsulfonate are particularly preferred. These emulsifiers are usually used in an amount of about 0.05 to 5 parts by mass per 100 parts by mass of the siloxane mixture. If the amount of emulsifier used is too small, the dispersion state becomes unstable and it becomes impossible to maintain an emulsified state with fine particle size. Also, if the amount of emulsifier used is too large, the resulting molded product will be discolored due to the emulsifier.

[0027] Methods for mixing the siloxane mixture, emulsifier, water, and / or acid catalyst include mixing by high-speed stirring and mixing using a high-pressure emulsifier such as a homogenizer. However, the method using a homogenizer is preferred because it reduces the particle size distribution of the polyorganosiloxane latex.

[0028] Acid catalysts used in the polymerization of polyorganosiloxanes include sulfonic acids such as aliphatic sulfonic acid, aliphatic-substituted benzenesulfonic acid, and aliphatic-substituted naphthalenesulfonic acid, as well as mineral acids such as sulfuric acid, hydrochloric acid, and nitric acid. These acid catalysts can be used individually or in combination of two or more.

[0029] The polymerization temperature of the polyorganosiloxane is preferably 50°C or higher, and more preferably 80°C or higher. The polymerization time for the polyorganosiloxane is 2 hours or more, more preferably 5 hours or more, when the acid catalyst is mixed with the siloxane mixture, emulsifier and water, and polymerized by micronizing. When polymerizing by dropping the siloxane mixture into an aqueous solution of the acid catalyst into micronized latex, it is preferable to hold the solution for about 1 hour after the dropping of the latex is complete.

[0030] Polymerization can be stopped by cooling the reaction mixture and then neutralizing the latex with an alkaline substance such as caustic soda, caustic potash, or sodium carbonate.

[0031] A composite rubber can be obtained by impregnating the polyorganosiloxane latex produced in this manner with a component consisting of alkyl acrylate and polyfunctional alkyl (meth)acrylate, and then polymerizing it. The amount of polyorganosiloxane in the composite rubber (B) according to the present invention is not particularly limited, but 1 to 25% by mass is preferred. If the polyorganosiloxane content in the composite rubber (B) is less than 1% by mass, the amount of polyorganosiloxane that can be incorporated into the resin composition will be small, resulting in a low level of UV-C resistance. If the polyorganosiloxane content in the composite rubber (B) exceeds 25% by mass, the efficiency of separation and recovery of the graft copolymer by salting out and coagulation of the graft polymer latex may decrease. From this viewpoint, the polyorganosiloxane content in the composite rubber (B) is more preferably 6 to 20% by mass, and even more preferably 10 to 20% by mass.

[0032] <Polyalkyl acrylate> The polyalkyl acrylate constituting the composite rubber (G) consists of alkyl acrylate and polyfunctional alkyl (meth)acrylate. Here, "(meth)acrylate" refers to either or both "acrylate" and "methacrylate".

[0033] Examples of alkyl acrylates include methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, and 2-ethylhexyl acrylate, which can be used individually or in combination of two or more. Of these, n-butyl acrylate is preferred.

[0034] Examples of polyfunctional alkyl (meth)acrylates include allyl methacrylate, ethylene glycol dimethacrylate, propylene glycol dimethacrylate, 1,3-butylene glycol dimethacrylate, 1,4-butylene glycol dimethacrylate, triallyl cyanurate, and triallyl isocyanurate, which can be used alone or in combination of two or more. A preferred example of a polyfunctional alkyl (meth)acrylate is the combination of allyl methacrylate and 1,3-butylene glycol dimethacrylate.

[0035] The amount of polyfunctional alkyl (meth)acrylate used is preferably 0.1 to 20% by mass, more preferably 0.2 to 5% by mass, and even more preferably 0.2 to 1% by mass, of the component consisting of alkyl acrylate and polyfunctional alkyl (meth)acrylate. When the amount of polyfunctional alkyl (meth)acrylate used is within the above range, the mechanical properties of the resin composition are good.

[0036] Radical polymerization initiators used in polymerization include peroxides, azo initiators, or redox initiators combining oxidizing and reducing agents. Among these, redox initiators are preferred, and sulfoxylate initiators combining ferrous sulfate, disodium ethylenediaminetetraacetate, rongalit, and hydroperoxide are particularly preferred.

[0037] <Manufacturing method for composite rubber (G)> The composite rubber (G) comprising polyorganosiloxane and polyalkyl acrylate according to the present invention can be prepared by adding a mixture of the alkyl acrylate and polyfunctional alkyl (meth)acrylate to polyorganosiloxane latex and polymerizing it by reacting it with a conventional radical polymerization initiator. Methods for adding the acrylate component include mixing it all at once with the polyorganosiloxane latex and dropping it into the polyorganosiloxane latex at a constant rate. Considering the impact resistance of the resulting thermoplastic resin composition, the method of mixing it all at once with the polyorganosiloxane latex is preferred. For example, a method can be used to obtain the composite rubber (G) by impregnating the polyorganosiloxane latex produced by the above method with a component consisting of alkyl acrylate and polyfunctional alkyl (meth)acrylate and then polymerizing it.

[0038] <Content of polyorganosiloxanes and polyalkyl acrylates> The amount of polyorganosiloxane in the composite rubber (G) according to the present invention is not particularly limited, but is preferably 1 to 25% by mass. If the polyorganosiloxane content in the composite rubber (G) is 1% by mass or more, a large amount of polyorganosiloxane can be incorporated into the thermoplastic resin composition, resulting in excellent UV-C resistance. If the polyorganosiloxane content in the composite rubber (G) is 25% by mass or less, the efficiency of separation and recovery of the graft copolymer (A) by salting out and solidification of the graft polymer latex is excellent. The amount of polyorganosiloxane in the composite rubber (G) is more preferably 6 to 20% by mass, and even more preferably 10 to 20% by mass.

[0039] The amount of polyalkyl acrylate in the composite rubber (G) according to the present invention is not particularly limited, but is preferably 99 to 75% by mass. If the polyalkyl acrylate content in the composite rubber (G) is 75% by mass or more, the resulting thermoplastic resin composition exhibits excellent chemical resistance. If the polyalkyl acrylate content in the composite rubber (G) is 95% by mass or less, the resulting thermoplastic resin composition exhibits excellent UV-C resistance. The amount of polyalkyl acrylate in the composite rubber (G) is more preferably 94 to 80% by mass, and even more preferably 90 to 80% by mass.

[0040] <Mass-average particle diameter of composite rubber (G)> The mass-average particle diameter of the composite rubber (G) is preferably 0.08 to 0.16 μm. If the mass-average particle diameter is 0.08 μm or more, the resulting thermoplastic resin composition exhibits excellent impact resistance. On the other hand, if the mass-average particle diameter is 0.16 μm or less, the resulting thermoplastic resin composition exhibits excellent UV-C resistance. A more preferable mass-average particle diameter for the composite rubber (G) is 0.1 to 0.15 μm. The mass-average particle size of composite rubber (G) is measured by the method described in the Examples section below.

[0041] [Graft copolymer (A)] The graft copolymer (A) according to the present invention is produced by graft copolymerizing a composite rubber (G) with a monomer mixture (C) containing an aromatic alkenyl compound and a vinyl cyanide compound.

[0042] Aromatic alkenyl compounds used in graft copolymerization include α-methylstyrene, p-methylstyrene, vinyltoluene, t-butylstyrene, o-ethylstyrene, o-chlorostyrene, and o,p-dichlorostyrene. These may be used individually or in combination of two or more.

[0043] Examples of vinyl cyanide compounds include acrylonitrile, methacrylonitrile, and ethanolacrylonitrile, but acrylonitrile is particularly preferred. The vinyl cyanide compound may be used alone or in combination of two or more types. These can be used individually or in combination of two or more.

[0044] Of these, styrene and acrylonitrile are preferred when considering the impact resistance and thermal stability of the resulting thermoplastic resin composition.

[0045] The monomer mixture (C) may contain, in addition to aromatic alkenyl compounds and vinyl cyanide compounds, other vinyl monomers copolymerizable with them. Examples of other vinyl monomers copolymerizable with them include, but are not limited to, one or more unsaturated carboxylic acid ester monomers such as methyl (meth)acrylate, maleimide monomers such as N-methylmaleimide, N-cyclohexylmaleimide, and N-phenylmaleimide, unsaturated dicarboxylic acids such as maleic acid, unsaturated dicarboxylic acid anhydrides such as maleic anhydride, and unsaturated amides such as acrylamide. Note that "(meth)acrylic acid" refers to either or both acrylic acid and methacrylic acid.

[0046] The monomer mixture (C) preferably contains 65-85% by mass of an aromatic alkenyl compound, 15-35% by mass of a vinyl cyanide compound, and 0-15% by mass of other vinyl monomers copolymerizable with these (provided that the total of these amounts is 100% by mass). Within this range, the resulting thermoplastic resin composition tends to have excellent chemical resistance and UV-C resistance.

[0047] Various chain transfer agents can be added to the monomer mixture (C) used in graft copolymerization to adjust the molecular weight and grafting rate of the resulting graft copolymer (A).

[0048] Graft copolymerization can be carried out in one or multiple steps by radical polymerization technology by adding a monomer mixture (C) containing an aromatic alkenyl compound and a vinyl cyanide compound to the latex of a composite rubber (G). However, due to operational considerations such as graft composition and molecular weight adjustment, polymerization is preferably carried out in two or more steps.

[0049] The amount of monomer mixture (C) used in graft copolymerization is preferably 80 to 140 parts by mass, more preferably 100 to 120 parts by mass, per 100 parts by mass of composite rubber (G). Within this range, the chemical resistance of the resulting thermoplastic resin composition is improved. Furthermore, the polyorganosiloxane content in the resulting thermoplastic resin composition is more easily set within a suitable range, resulting in better UV-C resistance of the resulting thermoplastic resin composition.

[0050] During graft copolymerization, it is acceptable for not all compounds in the monomer mixture (C) to become graft components, but for some to exist as individual copolymers.

[0051] In graft copolymerization, emulsifiers may be added to stabilize the polymerized latex. The emulsifier used is not particularly limited, but preferred examples include cationic emulsifiers, anionic emulsifiers, and nonionic emulsifiers, and even more preferred examples include sulfonate emulsifiers or a combination of sulfate emulsifiers and carboxylate emulsifiers.

[0052] After graft polymerization is complete, the latex can be immersed in hot water containing a metal salt such as cassium acetate or aluminum sulfate, and the graft copolymer (A) can be separated and recovered by salting out and solidifying.

[0053] The content of the graft copolymer (A) in the thermoplastic resin composition of the present invention is preferably in the following order: 90-20 parts by mass, 90-30 parts by mass, 90-35 parts by mass, 80-20 parts by mass, 70-20 parts by mass, and 60-20 parts by mass, based on 100 parts by mass of the total of the graft copolymer (A) and the polymethyl methacrylate resin (M). Within this range, the content of polyorganosiloxane and polyalkyl acrylate in the composite rubber (G) in the resulting thermoplastic resin composition tends to be within a suitable range, and the UV-C resistance and chemical resistance of the resulting thermoplastic resin composition are improved.

[0054] The thermoplastic resin composition of the present invention may contain only one type of graft copolymer (A), or it may contain two or more different compositions such as composite rubber (G) or monomer mixture (C).

[0055] [Polymethyl methacrylate resin (M)] The polymethyl methacrylate resin (M) used in the present invention is not particularly limited, but preferably contains 80% by mass or more of methyl methacrylate units. The polymethyl methacrylate resin (M) may contain vinyl monomer units other than methyl methacrylate in an amount of 20% by mass or less. Examples of vinyl monomers other than methyl methacrylate include alkyl (meth)acrylates other than methyl methacrylate and styrene. From the viewpoint of UV-C resistance of the resulting thermoplastic resin composition, alkyl (meth)acrylates other than methyl methacrylate are preferred.

[0056] In the thermoplastic resin composition of the present invention, the content of polymethyl methacrylate resin (M) is preferably in the following order: 10-80 parts by mass, 10-70 parts by mass, 10-65 parts by mass, 20-80 parts by mass, 30-80 parts by mass, and 40-80 parts by mass, based on 100 parts by mass of the total of graft copolymer (A) and polymethyl methacrylate resin (M). Within this range, the content of polyorganosiloxane and polyalkyl acrylate in the composite rubber (G) in the resulting thermoplastic resin composition tends to be within a suitable range, and the UV-C resistance and chemical resistance of the resulting thermoplastic resin composition are improved.

[0057] The thermoplastic resin composition of the present invention may contain only one type of polymethyl methacrylate resin (M), or it may contain two or more types with different monomer compositions and physical properties.

[0058] [Antibacterial agent (K)] The antibacterial agent (K) used in this invention can be any known antibacterial agent. Examples of antibacterial components of antibacterial agents (K) include antibacterial components containing silver, inorganic antibacterial components that do not contain silver, organic antibacterial components, and combinations thereof. As long as the antibacterial component contains silver (silver atoms), the type of silver is not particularly limited. Furthermore, the form of silver is not particularly limited; for example, it can be contained in the form of metallic silver, silver ions, or silver salts.

[0059] Examples of silver salts include silver acetate, silver acetylacetate, silver azide, silver acetylide, silver arsenate, silver benzoate, silver hydrogen fluoride, silver bromate, silver bromide, silver carbonate, silver chloride, silver chlorate, silver chromate, silver citrate, silver cyanate, silver cyanide, (cis,cis-1,5-cyclooctadiene)-1,1,1,5,5,5-hexafluoroacetylacetate silver, diethyldithiocarbamate silver, silver(I) fluoride, silver(II) fluoride, 7,7-dimethyl-1,1,1,2,2,3,3-heptafluoro-4,6-octanedionate silver, silver hexafluoroantimone, silver hexafluoroarsenate, silver hexafluorophosphate, silver iodate, and silver iodide. Examples include silver isothiocyanate, potassium silver cyanide, silver lactate, silver molybdate, silver nitrate, silver nitrite, silver(I) oxide, silver(II) oxide, silver oxalate, silver perchlorate, silver perfluorobutyrate, silver perfluoropropionate, silver permanganate, silver perrhenate, silver phosphate, silver picrate monohydrate, silver propionate, silver selenate, silver selenide, silver selenite, silver sulfadiazine, silver sulfate, silver sulfide, silver sulfite, silver telluride, silver tetrafluoroborate, silver tetraiodomucurate, silver tetratungstate, silver thiocyanate, silver p-toluenesulfonate, silver trifluoromethanesulfonate, silver trifluoroacetate, and silver vanadate.

[0060] Furthermore, examples of silver complexes, which are a form of silver salt, include histidine silver complex, methionine silver complex, cysteine ​​silver complex, aspartate silver complex, pyrrolidone carboxylate silver complex, oxotetrahydrofuranate silver complex, or imidazole silver complex.

[0061] Examples of inorganic antibacterial components that do not contain silver include compounds containing metals other than silver, such as copper compounds including metallic copper and copper oxide, gold compounds including metallic gold and gold oxide, lead compounds including metallic lead and lead oxide, platinum compounds including metallic platinum and platinum oxide, nickel compounds including metallic nickel and nickel oxide, aluminum compounds including metallic aluminum and aluminum oxide, tin compounds including metallic tin and tin oxide, zinc compounds including metallic zinc and zinc oxide, iron compounds including metallic iron and iron oxide, bismuth compounds including metallic bismuth and bismuth oxide, and inorganic compounds containing ammonium salts.

[0062] Examples of organic antimicrobial components include phenol ether derivatives, imidazole derivatives, sulfone derivatives, N-haloalkylthio compounds, anilide derivatives, pyrrole derivatives, ammonium salt-containing organic compounds, pyridine compounds, triazine compounds, benzoisothiazoline compounds, and isothiazoline compounds.

[0063] The types of ammonium salt-containing inorganic compounds and ammonium salt-containing organic compounds are not particularly limited, but quaternary ammonium salts are particularly preferred. Examples of ammonium salt-containing inorganic compounds include ammonium chloride, ammonium nitrate, and ammonium sulfate. Examples of ammonium salt-containing organic compounds include ammonium formate, ammonium acetate, benzalkonium chloride, alkyldiaminoethylglycine hydrochloride, and ammonium salt-containing polymers. Examples of ammonium salt-containing polymers include salts of amino group-containing resins, such as dimethylaminoethyl methacrylate polymer, and resins having ammonium salt-containing monomers as structural units, such as diallyldimethylammonium chloride polymer. The neutralized chitosan described later is also one form of an amino group-containing resin salt.

[0064] These antibacterial agents (K) may be used individually or in combination of two or more.

[0065] The amount of antimicrobial agent (K) in the thermoplastic resin composition of the present invention is preferably in the following order: 0.1 to 10 parts by mass, 0.1 to 5.0 parts by mass, 0.1 to 3.0 parts by mass, 0.1 to 1.0 parts by mass, and 0.2 to 0.6 parts by mass, based on 100 parts by mass of the total of the graft copolymer (A) and the polymethyl methacrylate resin (M). If the amount of antimicrobial agent (K) is within the above range, sufficient antimicrobial activity can be obtained from the antimicrobial agent (K).

[0066] [Other ingredients] The thermoplastic resin composition of the present invention may contain other components besides the graft copolymer (A), polymethyl methacrylate resin (M), and antibacterial agent (K), as long as the objectives of the present invention are not impaired. Other components include weather-resistance enhancers such as UV absorbers and light stabilizers, lubricants, plasticizers, flame retardants, flame retardant enhancers, colorants, and other additives, as well as resins other than graft copolymers (A) and polymethyl methacrylate resins (M).

[0067] <UV absorber> Various commercially available UV absorbers can be used, including benzophenone-based, benzotriazole-based, triazine-based, and salicylate-based types.

[0068] Examples of benzophenone-based UV absorbers include 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxy-2'-carboxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 2-hydroxy-4-n-dodecyloxybenzophenone, 2-hydroxy-4-n-octadecyloxybenzophenone, 2-hydroxy-4-benzyloxybenzophenone, 2-hydroxy-4-methoxy-5-sulfobenzophenone, 2-hydroxy-5-chlorobenzophenone, 2,4-dihydroxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, and 2,2',4,4'-tetrahydroxybenzophenone.

[0069] Examples of benzotriazole-based ultraviolet absorbers include hydroxyphenyl-substituted benzotriazole compounds such as 2-(2-hydroxy-5-methylphenyl)benzotriazole, 2-(2-hydroxy-5-t-butylphenyl)benzotriazole, 2-(2-hydroxy-3,5-dimethylphenyl)benzotriazole, 2-(2-methyl-4-hydroxyphenyl)benzotriazole, 2-(2-hydroxy-3-methyl-5-t-butylphenyl)benzotriazole, 2-(2-hydroxy-3,5-di-t-amylphenyl)benzotriazole, and 2-(2-hydroxy-3,5-di-t-butylphenyl)benzotriazole. Examples of triazine-based UV absorbers include 2-[4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine-2-yl]-5-(octyloxy)phenol and 2-(4,6-diphenyl-1,3,5-triazine-2-yl)-5-(hexyloxy)phenol.

[0070] Examples of salicylic acid ester-based UV absorbers include phenyl salicylate and p-octylphenyl salicylate.

[0071] The above-mentioned ultraviolet absorbers can be used individually or in combination of two or more types.

[0072] When the thermoplastic resin composition of the present invention contains an ultraviolet absorber, its content is preferably 0.05 to 1.0 parts by mass, more preferably 0.1 to 0.5 parts by mass, based on 100 parts by mass of the total of the graft copolymer (A) and the polymethyl methacrylate resin (M).

[0073] <Light stabilizer> As a light stabilizer, a hindered amine-based light stabilizer can be suitably used. Hindered amine light stabilizers do not absorb ultraviolet light like UV absorbers, but they show a remarkable synergistic effect when used in combination with UV absorbers.

[0074] Examples of hindered amine-based light stabilizers include dimethyl-1-(2-hydroxyethyl)-4-hydroxy-2,2,6,6-tetramethylpiperidine polycondensate succinate, poly[{6-(1,1,3,3-tetramethylbutyl)amino-1,3,5-triazine-2,4-diyl}{(2,2,6,6-tetramethyl-4-piperidyl)imino}hexamethylene{{2,2,6,6-tetramethyl-4-piperidyl}imino}], N,N'- Examples include bis(3-aminopropyl)ethylenediamine-2,4-bis[N-butyl-N-(1,2,2,6,6-pentamethyl-4-piperidyl)amino]-6-chloro-1,3,5-triazine condensate, bis(2,2,6,6-tetramethyl-4-piperidyl)sebacate, and 2-(3,5-di-tert-4-hydroxybenzyl)-2-n-butylmalonate bis(1,2,2,6,6-pentamethyl-4-piperidyl). The above-mentioned stabilizers can be used individually or in combination of two or more types.

[0075] If the thermoplastic resin composition of the present invention contains a light stabilizer, its content is preferably 0.1 to 1.0 parts by mass, more preferably 0.3 to 0.6 parts by mass, based on 100 parts by mass of the total of the graft copolymer (A) and the polymethyl methacrylate resin (M).

[0076] <Other resins> The thermoplastic resin composition of the present invention may contain one or more other resins other than the graft copolymer (A) and the polymethyl methacrylate resin (M), as long as the objectives of the present invention are not impaired. In this case, it is preferable that the other resins amount to 50 parts by mass or less in a total of 100 parts by mass of the graft copolymer (A), the polymethyl methacrylate resin (M), and the other resins.

[0077] [Method for producing thermoplastic resin compositions] The thermoplastic resin composition of the present invention can be produced by various methods, such as melt-kneading the aforementioned graft copolymer (A), polymethyl methacrylate resin (M), and antibacterial agent (K), along with any additional additives or other resins as needed, using a Banbury mixer, rolls, and a single-screw or multi-screw extruder.

[0078] [Polyorganosiloxane content in thermoplastic resin compositions] The thermoplastic resin composition of the present invention preferably contains the aforementioned composite rubber (G), polymethyl methacrylate resin (M), antibacterial agent (K), and other components as needed, such that the polyorganosiloxane content in 100% by mass of the thermoplastic resin composition is 1 to 10% by mass, particularly 3 to 7% by mass. UV-C resistance is further improved when the polyorganosiloxane content in the thermoplastic resin composition is within this range.

[0079] [Molded product] The molded article of the present invention is obtained by molding the thermoplastic resin composition of the present invention using a known molding method. Examples of molding methods include injection molding, press molding, extrusion molding, vacuum forming, and blow molding.

[0080] The molded articles of the present invention, obtained by molding the thermoplastic resin composition of the present invention, have antibacterial properties and do not suffer from defects such as embrittlement or discoloration even when wiped with disinfectant or sterilized with deep ultraviolet (UV-C) light. Therefore, they are exposed to disinfectant and UV-C light during use, and are subjected to sterilization and disinfection by wiping with disinfectant or UV-C irradiation. They are useful as components of sterilization and disinfection devices, specifically as components around sterilization lamps, fan components for medical protective clothing, hygiene products such as jet towels, toilet seats, combs, and razors, in-vehicle devices, home appliances, furniture, and daily necessities, etc., where they are touched by hand. However, the applications of the molded articles of the present invention are not limited to components of sterilization and disinfection equipment, but are also useful for other general applications. [Examples]

[0081] To further illustrate the present invention, examples and comparative examples are given below, but these examples are not intended to limit the present invention. In the following reference examples, embodiments, and comparative examples, "parts" and "%" refer to "parts by mass" and "% by mass," respectively, unless otherwise specified.

[0082] <Measurement of average particle size of polyorganosiloxane> Using a particle size analyzer (MATEC APPLIED SCIENCES, "CHDF-2000") and 2XGR500 (product name) as the carrier solution, the mass-based volume-average particle size of polyorganosiloxanes was measured.

[0083] <Measurement of average particle size of composite rubber> The volume-average particle size of composite rubber latex was measured using a NanoTrac particle size distribution analyzer (UPA-EX150, manufactured by Nikkiso Co., Ltd.) with deionized water as the measurement solvent. This was defined as the average particle size of the composite rubber.

[0084] <Evaluation of UV-C resistance> A 50mm x 50mm x 3mm thick test specimen was subjected to an Iwasaki Electric GL15W UV-C lamp (wavelength 254nm, illuminance 5.175mW / cm²). 2 Assuming that sterilization by UV irradiation is performed twice a day for 10 minutes each time, using an irradiation distance of 80 mm, the cumulative exposure after one year would be approximately 21,900 mW·sec / cm². 2 The following evaluation was conducted based on this assumption. (evaluation) The color of an unirradiated sample was measured using a spectrophotometer (Konica Minolta Optics, CM-3500d) with the SCI method (including specular reflection), and the cumulative exposure was 90,000 mW·sec / cm². 2 The difference ΔE in the measured value at the point when it reached (equivalent to approximately 4 years of use) was judged according to the following criteria. ○: Minimal yellowing visible to the naked eye, and a color difference ΔE of less than 15 according to the SCI method. △: Slight yellowing is visible to the naked eye, and the color difference ΔE by SCI method is 15 or greater but less than 20. ×: Yellowing is visible to the naked eye, and the color difference ΔE by the SCI method is 20 or more.

[0085] <Evaluation of chemical resistance> (Bending form constant strain method) A test specimen measuring 150 mm x 10 mm to 13 mm with a thickness of 2 mm was prepared and fixed to a 0.7% constant strain jig. A cotton ball soaked in 99.5% ethanol was placed in the center of the test specimen (75 mm from both ends), and after standing for 24 hours at 23°C, it was evaluated from the following perspectives. ○: No cracks occur on the surface of the test specimen while it is mounted in the jig, and furthermore, no cracks occur even when excessive strain is applied after removal from the jig. △: No cracks appear on the surface of the test specimen when it is attached to the fixture, but cracks appear when excessive strain is applied after removal from the fixture. ×: When cracks occur on the surface of the test specimen while it is mounted in the jig.

[0086] <Evaluation of antibacterial properties> A test specimen measuring 50 mm x 50 mm with a thickness of 3 mm was prepared, and an antibacterial test was conducted under the following conditions in accordance with JIS Z2801 (2012). Test strain: Staphylococcus aureus NBRC 12732 Judgment conditions ○: Effective if the antibacterial activity value is 2.0 or higher. ×: The antibacterial activity value is less than 2.0, so sufficient effect cannot be obtained.

[0087] [Reference Example 1: Preparation of Polyorganosiloxane Latex] 98 parts of octamethylcyclotetrasiloxane and 2 parts of γ-mecryloyloxypropyl dimethoxymethylsilane were mixed to obtain 100 parts of a siloxane mixture. 300 parts of distilled water containing 0.65 parts of sodium dodecylbenzenesulfonate were added to this mixture, and the mixture was stirred in a homomixer at 9000 rpm for 2 minutes. The mixture was then passed through a homogenizer at a pressure of 30 MPa to obtain a stable pre-mixed organosiloxane latex. Meanwhile, 10 parts of dodecylbenzenesulfonic acid and 90 parts of distilled water were added to a reactor equipped with a reagent injection container, condenser, jacket heater, and stirring device to prepare a 10% aqueous solution of dodecylbenzenesulfonic acid. This aqueous solution was heated to 85°C, and the pre-mixed organosiloxane latex was added dropwise over 4 hours. After the addition was complete, the temperature was maintained for 1 hour, and then the mixture was cooled. The reaction product was then neutralized with an aqueous solution of caustic soda to obtain the latex. The latex obtained in this manner was dried at 170°C for 30 minutes, and its solid content was determined to be 18.0%. The volume-average particle size of the polyorganosiloxane in the latex was 0.07 μm.

[0088] [Reference Example 2: Preparation of Composite Rubber (G-1) Latex] In a reactor equipped with a reagent injection container, a condenser, a jacket heater, and a stirrer, 38.9 parts of polyorganosiloxane latex prepared in Reference Example 1 and 0.18 parts of polyoxyethylene alkylphenyl ether sulfate ("Emal NC-35," manufactured by Kao Corporation) were taken, and after adding and mixing with 148.5 parts of distilled water, a mixture of 42 parts of n-butyl acrylate, 0.3 parts of allyl methacrylate, 0.1 parts of 1,3-butylene glycol dimethacrylate, and 0.11 parts of t-butyl hydroperoxide was added. The atmosphere of the reactor was replaced with nitrogen by passing a nitrogen stream through it, and the temperature was raised to 60°C. When the internal liquid temperature reached 60°C, an aqueous solution prepared by dissolving 0.000075 parts of ferrous sulfate, 0.000225 parts of ethylenediaminetetraacetate disodium salt, and 0.2 parts of Longalit in 10 parts of distilled water was added, and radical polymerization was started. The polymerization of the acrylate component caused the liquid temperature to rise to 78°C. This state was maintained for 1 hour to complete the polymerization of the acrylate component, yielding a composite rubber (G-1) latex of polyorganosiloxane and butyl acrylate rubber. A portion of the latex was sampled, and the volume-average particle size of the obtained composite rubber (G-1) was measured to be 0.13 μm.

[0089] [Reference Example 3: Preparation of Graft Copolymer (A-1)] After the liquid temperature of the composite rubber (G-1) latex above decreased to 70°C inside the reactor, an aqueous solution of 0.25 parts of Longalit dissolved in 10 parts of distilled water was added, and then a mixture of 2.5 parts of acrylonitrile, 7.5 parts of styrene, and 0.05 parts of t-butyl hydroperoxide was added dropwise over 2 hours to polymerize. After the dropwise addition was complete, the temperature was maintained at 60°C for 1 hour, and then an aqueous solution of 0.001 parts of ferrous sulfate, 0.003 parts of ethylenediaminetetraacetate disodium salt, 0.2 parts of Longalit, and 0.18 parts of "Emal NC-35" (manufactured by Kao Corporation) dissolved in 10 parts of distilled water was added, and then a mixture of 10 parts of acrylonitrile, 30 parts of styrene, and 0.2 parts of t-butyl hydroperoxide was added dropwise over 2 hours to polymerize. After the dropwise addition was complete, the temperature was maintained at 60°C for 0.5 hours, then 0.05 parts of cumene hydroperoxide were added, and the temperature was maintained at 60°C for another 0.5 hours before cooling. The resulting graft copolymer latex was coagulated, dehydrated, and dried with an aqueous calcium acetate solution to obtain graft copolymer (A-1).

[0090] [Reference Example 4: Preparation of Graft Copolymer (a-2)] 150 parts water, 3.3 parts potassium tallow fatty acid salt, 0.14 parts potassium hydroxide, 0.3 parts sodium pyrophosphate, and 0.20 parts tert-dodecyl mercaptan were charged into a reactor, followed by 100 parts 1,3-butadiene, and the temperature was raised to 62°C. Next, 0.12 parts potassium persulfate was injected under pressure to start polymerization. The reaction was carried out over 10 hours, reaching 75°C. After further reaction at 75°C for 1 hour, 0.08 parts sodium formaldehyde sulfoxylate were injected under pressure. After removing the remaining 1,3-butadiene, the polymer was taken out to obtain polybutadiene latex (solid content 35%). The mass-average particle size of the obtained polybutadiene rubber was 0.08 μm. To 100 parts (solids) of the obtained polybutadiene rubber, 2 parts (solids) of copolymer latex (solids) consisting of 85% n-butyl acrylate units and 15% methacrylic acid units, with a volume-average particle size of 0.11 μm, were added while stirring. Stirring was continued for 30 minutes to obtain enlarged polybutadiene latex with an average particle size of 0.28 μm. Next, 180 parts of water (including water in the latex of the enlarged polybutadiene latex), 70 parts of enlarged polybutadiene latex (on a solid content basis), and 0.13 parts of disproportionated potassium rosinate were added to a closed reactor equipped with a reagent injection container, condenser, nitrogen purging device, jacket heater, and stirrer. The internal temperature of the reactor was raised to 55°C while purging with nitrogen and maintained for 30 minutes. Then, a solution of 0.15 parts of sodium pyrophosphate, 0.008 parts of ferrous sulfate heptahydrate, and 0.3 parts of glucose dissolved in 8 parts of deionized water was added. Subsequently, a mixture of 7.5 parts of acrylonitrile, 22.5 parts of styrene, 0.07 parts of cumene hydroperoxide, and 0.09 parts of tert-dodecyl mercaptan was added dropwise over 5 hours to polymerize. After the dropwise addition was complete, the mixture was stirred for 30 minutes while maintaining the internal temperature at 55°C, and then cooled to obtain graft copolymer latex. The obtained graft copolymer latex was diluted 1.25 times with distilled water and gradually added dropwise to a 3% sulfuric acid aqueous solution at 50°C. After the entire volume had been added, the temperature was raised to 90°C and held for 5 minutes to allow it to solidify. The solidified material was then centrifuged using a filter cloth, and the wet powder-like graft copolymer was dried to obtain graft copolymer (a-2).

[0091] [Reference Example 5: Preparation of Graft Copolymer (a-3)] In a 20-liter stainless steel autoclave equipped with ribbon-type agitator blades, a continuous additive addition device, and a thermometer, 22 parts of ethylene-propylene copolymer (ethylene / propylene = 78 / 22 (molar ratio), Mooney viscosity (ML1+4, 100℃): 20, melting point (Tm): 40℃, glass transition temperature (Tg): -50℃), 55 parts of styrene, 23 parts of acrylonitrile, 0.5 parts of t-dodecyl mercaptan, and 110 parts of toluene were charged as an ethylene-α-olefin rubber polymer. The internal temperature was raised to 75℃, and the contents of the autoclave were stirred for 1 hour to obtain a homogeneous solution. Subsequently, 0.45 parts of t-butyl peroxyisopropyl monocarbonate were added, and the internal temperature was further raised until it reached 100℃. After that, the polymerization reaction was carried out while maintaining this temperature and stirring speed at 100 rpm. Four hours after the start of the polymerization reaction, the internal temperature was raised to 120°C, and the reaction was carried out for another 2 hours while maintaining this temperature to complete the polymerization reaction. After that, the internal temperature was cooled to 100°C, and 0.2 parts of octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenol)-propionate and 0.02 parts of dimethyl silicone oil; KF-96-100cSt (product name: Shin-Etsu Silicone Co., Ltd.) were added. The reaction mixture was then removed from the autoclave, unreacted products and solvent were removed by steam distillation, and volatile components were substantially degassed using a 40 mmφ vented extruder (cylinder temperature 220°C, vacuum 760 mmHg), and the mixture was pelletized to obtain graft copolymer (a-3).

[0092] [Reference Example 6: Preparation of Graft Copolymer (a-4)] In the same procedure as for the polybutadiene latex obtained during the preparation of graft copolymer (a-2), 20 parts of polybutadiene latex (as solids) with a solids concentration of 35% and an average particle size of 0.08 μm were added while stirring to copolymer latex (as solids) with an average particle size of 0.10 μm consisting of 82% n-butyl acrylate units and 18% methacrylic acid units. Stirring was continued for 30 minutes to obtain a hypertrophied diene-based rubber latex with an average particle size of 0.36 μm. The resulting enlarged diene rubber latex (20 parts as solid content) was charged into a reactor, 1 part disproportionated potassium rosinate, 150 parts deionized water, and a monomer mixture of the following composition were added, the reactor was purged with nitrogen, and the temperature was raised to 50°C (internal temperature). (Composition of monomer mixture) n-butyl acrylate: 80 parts Allyl methacrylate: 0.32 parts Ethylene glycol dimethacrylate: 0.16 parts

[0093] Furthermore, a solution prepared by dissolving 0.0002 parts ferrous sulfate, 0.0006 parts disodium ethylenediaminetetraacetate, and 0.25 parts Longalit in 10 parts deionized water was added to the reactor and the reaction was allowed to proceed. The internal temperature at the end of the reaction was 75°C. The temperature was then raised to 80°C and the reaction was continued for 1 hour to obtain a composite rubber polymer latex of hypertrophied diene rubber and polybutyl acrylate rubber. The polymerization rate was 98.8%. A composite rubber polymer latex (50 parts as solid content) of enlarged diene rubber and polybutyl acrylate rubber was charged into a reactor, diluted with 140 parts of deionized water, and heated to 70°C. Separately, 50 parts of a monomer mixture consisting of acrylonitrile / styrene = 29 / 71 (mass ratio) was mixed with 0.35 parts of benzoyl peroxide and then nitrogen-purged. The monomer mixture was added at a rate of 15 parts / hour to the reactor containing the rubbery polymer latex using a metering pump. After all of the monomer mixture had been added, the temperature in the reactor was raised to 80°C and stirring was continued for 30 minutes to obtain graft copolymer latex. The polymerization rate was 99%. The obtained graft copolymer latex was diluted 1.25 times with distilled water and gradually added dropwise to a 3% sulfuric acid aqueous solution at 50°C. After the entire volume had been added, the temperature was raised to 90°C and held for 5 minutes to allow it to solidify. The solidified material was then centrifuged using a filter cloth, and the wet powder-like graft copolymer was dried to obtain graft copolymer (a-4).

[0094] [Reference Example 7: Preparation of Acrylonitrile-Styrene Copolymer] A monomer mixture consisting of 125 parts water, 0.4 parts calcium phosphate, 0.003 parts potassium alkenylsuccinate, 0.05 parts 1,1,3,3-tetramethylbutyl peroxy-2-ethylhexanoate, 0.04 parts 1,1-di(tert-hexylperoxy)cyclohexane, 0.04 parts tert-butyl peroxy-2-ethylhexyl carbonate, 0.45 parts tert-dodecyl mercaptan, 26 parts acrylonitrile, and 74 parts styrene was charged into a reactor and reacted. The reaction was carried out by sequentially adding water, acrylonitrile, and a portion of the styrene, heating from a starting temperature of 65°C for 6.5 hours, and then reaching 125°C. After further reaction at 125°C for 1 hour, a slurry of acrylonitrile-styrene copolymer was obtained. After cooling, this slurry was centrifuged to dehydrate it and obtain acrylonitrile-styrene copolymer (AS copolymer). The mass-average molecular weight of the obtained co-AS copolymer was 114,000.

[0095] [Polymethyl methacrylate resin (M)] The following polymethyl methacrylate resins (M) were prepared. MMA resin (M-1): "Acrypet VHS" (product name) manufactured by Mitsubishi Chemical Corporation. MMA resin (M-2): "Acrypet SV" (product name) manufactured by Mitsubishi Chemical Corporation.

[0096] [Antibacterial agent (K)] The following were used as antibacterial agents (K): Antibacterial agent (K-1): "Bactekiller BM-102TG" (product name) manufactured by Fuji Chemical Co., Ltd. Antibacterial agent (K-2): "Zeomic XAW50D-T" (product name) manufactured by Sinanen Zeomic Co., Ltd. Antibacterial agent (K-3): "Novaron AGZ330" (product name) manufactured by Toagosei Co., Ltd.

[0097] [Other additives] Light stabilizer: ADEKA Corporation's "ADEKA Stab (registered trademark) LA-77Y" UV absorber: ADEKA Corporation's "ADEKA Stab (registered trademark) LA-36"

[0098] [ See Example 1 for reference. Examples 2 [~6 and Comparative Examples 1~6] A thermoplastic resin composition was prepared by mixing each raw material in the proportions (parts by mass) shown in Table 1. The obtained thermoplastic resin compositions were melt-kneaded at a temperature of 230°C using a twin-screw extruder with a screw diameter of 30 mm (TEX30α manufactured by Japan Steel Works Ltd.) to form pellets of the thermoplastic resin composition. For the UV-C resistance evaluation, the resin composition was further melt-kneaded with 4 parts by mass of CR-60-2 manufactured by Ishihara Industries Co., Ltd. as titanium dioxide to obtain pellets. The obtained thermoplastic resin composition pellets were used to evaluate the aforementioned UV-C resistance, chemical resistance, and antibacterial properties, and the results are shown in Table 1. Table 1 also includes the polyorganosiloxane content in the thermoplastic resin composition.

[0099] [Table 1]

[0100] Table 1 shows that the thermoplastic resin composition of the present invention, which contains a graft copolymer (A), a polymethyl methacrylate resin (M), and an antibacterial agent (K), exhibits excellent UV-C resistance, chemical resistance, and antibacterial properties. In contrast, Comparative Example 1, which does not contain the antibacterial agent (K), exhibits inferior antibacterial activity. Among Comparative Examples 2 to 5, which used a graft copolymer different from the graft copolymer (A) according to the present invention and did not contain polymethyl methacrylate resin (M), Comparative Examples 2 and 3 showed inferior UV-C resistance and antibacterial properties, while Comparative Examples 4 and 5 showed inferior results in all items. Comparative Example 6 contains a graft copolymer (A) but does not contain a polymethyl methacrylate resin (M), and therefore has poor UV-C resistance.

Claims

1. A graft copolymer (A) is obtained by graft polymerizing a monomer mixture (C) containing an aromatic alkenyl compound and a vinyl cyanide compound in the presence of a composite rubber (G) consisting of a polyorganosiloxane and a polyalkyl acrylate, and the material contains a polymethyl methacrylate resin (M) and an antibacterial agent (K). A thermoplastic resin composition comprising 15 to 47 parts by mass of the polymethyl methacrylate resin (M) in a total of 100 parts by mass of the graft copolymer (A) and the polymethyl methacrylate resin (M).

2. The thermoplastic resin composition according to claim 1, wherein the polymethyl methacrylate resin (M) contains 80% by mass or more of methyl methacrylate units and 20% by mass or less of alkyl (meth)acrylate units other than methyl methacrylate.

3. The thermoplastic resin composition according to claim 1 or 2, wherein the resin component in the thermoplastic resin composition consists of the graft copolymer (A) and the polymethyl methacrylate resin (M).

4. A thermoplastic resin composition according to any one of claims 1 to 3, which is a thermoplastic resin composition for deep ultraviolet sterilization.

5. A molded article obtained by molding the thermoplastic resin composition according to any one of Claims 1 to 4.

6. A component of a sterilization and disinfection device including the molded product described in Claim 5.

7. A medical protective clothing fan member comprising the molded article described in Claim 5.

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