Thermoplastic elastomer composition

Abstract

To provide a thermoplastic elastomer composition that allows effective dispersion of a phosphorus-based flame retardant, exhibits superior flame retardancy, ensures high smoothness, and yields a molded article having excellent mechanical properties and high flexibility (rubber elasticity).SOLUTION: A thermoplastic elastomer composition comprises an olefin-based thermoplastic elastomer composition (A1) or a styrene-based thermoplastic elastomer composition (A2), a phosphorus-based flame retardant (B), and a copolymer (C) of an α-olefin and an unsaturated carboxylic acid.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a thermoplastic elastomer composition. [Background technology]

[0002] Thermoplastic elastomer compositions can be processed using ordinary molding machines for thermoplastic resins and have excellent recyclability and flexibility, and thus molded articles thereof are used in a variety of applications, such as machinery, electrical and electronic equipment, office automation equipment, automotive interior and exterior materials, electric vehicles, etc. In particular, they are expected to be used in electric vehicles and hybrid vehicles, as described below.

[0003] In recent years, research and development of electric and hybrid vehicles has been promoted as part of environmental measures, and the development of high-energy density batteries and weight reduction are being actively promoted in order to improve driving distance. However, such high-energy density batteries are accompanied by an increase in container size and an increase in reactive substances, which may lead to fire or explosion due to thermal runaway or accidental accidents. Therefore, molded articles used for battery housings (frames, casings, exteriors, covers, sealing materials, packings, etc.) are required to have high flame retardancy. Vulcanized rubber has been used as the above-mentioned sealant and packing, but in addition to flame retardancy, recyclability is an issue, so attempts have been made to develop materials that have the potential to achieve both recyclability and flame retardancy.

[0004] For example, Patent Document 1 proposes a flame-retardant thermoplastic elastomer composition containing a mineral oil-based softener and a flame retardant. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2015-124331 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, although the flame-retardant thermoplastic elastomer composition disclosed in Patent Document 1 provides excellent flame retardancy and mechanical properties to a molded article containing the elastomer composition, the smoothness and flexibility (rubber elasticity) of the article may be insufficient.

[0007] Therefore, the present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a thermoplastic elastomer composition which allows a phosphorus-based flame retardant to be well dispersed, exhibits excellent flame retardancy, and gives a molded article having high smoothness, excellent mechanical properties, and high flexibility (rubber elasticity). [Means for solving the problem]

[0008] The present inventors conducted extensive research to solve the above problems, and found that the above problems can be solved by a thermoplastic elastomer composition containing a specific thermoplastic elastomer composition (A1) or (A2), a phosphorus-based flame retardant, and a copolymer of an α-olefin and an unsaturated carboxylic acid. The present invention was completed based on these findings. That is, the present invention is as follows.

[0009] [1] A thermoplastic elastomer composition comprising an olefin-based thermoplastic elastomer composition (A1), a phosphorus-based flame retardant (B), and a copolymer of an α-olefin and an unsaturated carboxylic acid (C). [2] A thermoplastic elastomer composition comprising a styrene-based thermoplastic elastomer composition (A2), a phosphorus-based flame retardant (B), and a copolymer of an α-olefin and an unsaturated carboxylic acid (C). [3] The thermoplastic elastomer composition according to the above [1], wherein the olefin-based thermoplastic elastomer composition (A1) contains a crystalline polyolefin and an olefin-based copolymer rubber. [4] The thermoplastic elastomer composition according to the above [2], wherein the styrene-based thermoplastic elastomer composition (A2) contains a styrene-based rubber. [5] The thermoplastic elastomer composition according to any one of the above [1] to [4], wherein the phosphorus-based flame retardant (B) includes a compound having a melamine structure or a piperazine structure. [6] The thermoplastic elastomer composition according to any one of the above [1] to [5], wherein the phosphorus-based flame retardant (B) includes an intumescent flame retardant. [7] The thermoplastic elastomer composition according to any one of the above [1] to [6], wherein the unsaturated carboxylic acid in the copolymer (C) of an α-olefin and an unsaturated carboxylic acid includes maleic anhydride. [8] The thermoplastic elastomer composition according to any one of the above [1] to [7], wherein the proportion of the phosphorus-based flame retardant (B) relative to the total mass of the thermoplastic elastomer composition is 35 mass% or more. [9] The thermoplastic elastomer composition according to any one of the above [1] to [8], wherein the ratio of the copolymer (C) of an α-olefin and an unsaturated carboxylic acid to the phosphorus-based flame retardant (B) is 10 mass% or less.

[10] The thermoplastic elastomer composition according to any one of the above [1], [3], and [5] to [9], wherein the ratio of the combined mass of the olefin-based thermoplastic elastomer composition (A1), the phosphorus-based flame retardant (B) and the copolymer (C) to the total mass of the thermoplastic elastomer composition is 60 mass% or more.

[11] The thermoplastic elastomer composition according to any one of the above [2] and [4] to [9], wherein the ratio of the combined mass of the styrene-based thermoplastic elastomer composition (A2), the phosphorus-based flame retardant (B) and the copolymer (C) to the total mass of the thermoplastic elastomer composition is 60 mass% or more.

[12] A pellet comprising the thermoplastic elastomer composition according to any one of the above [1] to

[11] .

[13] A molded article comprising the thermoplastic elastomer composition according to any one of the above [1] to

[11] .

[14] The molded article according to

[13] above, having a durometer hardness of 39 or more using a type A durometer measured in accordance with JIS K 6253-3:2023.

[15] The molded article according to

[13] or

[14] above, having a flame retardancy of V-0 according to the UL94 standard at a thickness of 1.6 mm. Effect of the Invention

[0010] According to the present invention, it is possible to provide a thermoplastic elastomer composition in which a phosphorus-based flame retardant is well dispersed, exhibiting excellent flame retardancy, and giving a molded article having high smoothness, excellent mechanical properties, and high flexibility (rubber elasticity). Furthermore, a molded article formed from the thermoplastic elastomer composition of the present invention can be recycled by reheating the molded article after use.

[0011] The following provides a detailed description of an embodiment of the present invention (hereinafter, sometimes referred to as the present embodiment); however, the following description is an example of an embodiment of the present invention, and the present invention is in no way limited to the contents thereof.

[0012] [Thermoplastic elastomer composition] The thermoplastic elastomer composition according to the first aspect of the present invention (hereinafter also referred to as "the thermoplastic elastomer composition (I)") contains an olefin-based thermoplastic elastomer composition (A1), a phosphorus-based flame retardant (B), and a copolymer of an α-olefin and an unsaturated carboxylic acid (C). The thermoplastic elastomer composition according to the second aspect of the present invention (hereinafter also referred to as "the thermoplastic elastomer composition (II)") contains a styrene-based thermoplastic elastomer composition (A2), a phosphorus-based flame retardant (B), and a copolymer of an α-olefin and an unsaturated carboxylic acid (C). Both the thermoplastic elastomer composition (I) and the thermoplastic elastomer composition (II) exhibit excellent flame retardancy and are excellent in moldability, and thus the molded articles thereof have high smoothness, excellent mechanical properties, and high flexibility (rubber elasticity).

[0013] [Olefin-based thermoplastic elastomer composition (A1)] The thermoplastic elastomer composition (I) contains an olefin-based thermoplastic elastomer composition (A1). The olefin-based thermoplastic elastomer composition (A1) is not particularly limited as long as it is a thermoplastic elastomer containing an olefin-based copolymer rubber, but from the viewpoints of light weight, stable rubber elasticity, excellent mechanical properties and good moldability, it is preferable that the composition contains a crystalline polyolefin and an olefin-based copolymer rubber.

[0014] The crystalline polyolefin may be an unmodified crystalline polyolefin, or may be a modified crystalline polyolefin obtained by modifying a crystalline polyolefin with at least one functional group selected from the group consisting of an acid anhydride group, a carboxyl group, an amino group, an imino group, an alkoxysilyl group, a silanol group, a silyl ether group, a hydroxyl group, and an epoxy group.

[0015] Examples of crystalline polyolefins include propylene-based polymers, ethylene-based polymers, etc. These may be used alone or in combination of two or more.

[0016] Examples of the propylene-based polymer include propylene homopolymers and propylene-based copolymers, which are random or block copolymers of polypropylene and ethylene or an α-olefin such as butene-1 or hexene-1. The melt flow rate of the propylene polymer (JIS K 7210, 230°C, 21.2N load) is not particularly specified, but is usually 0.05 to 200g / 10min, preferably 0.05 to 100g / 10min, and more preferably 0.1 to 80g / 10min. By controlling the melt flow rate within the above range, excellent moldability and good appearance of the obtained molded product can be obtained, and mechanical properties, particularly tensile breaking strength, can be controlled within a desired range.

[0017] The propylene polymer may be a commercially available product. Commercially available polypropylene may be procured from the manufacturers listed below and may be appropriately selected. Available commercial products include Novatec® PP from Japan Polypropylene, Prime Polypro® from Prime Polymer, Sumitomo Noblen® from Sumitomo Chemical, polypropylene block copolymer from SunAllomer, Moplen® and Circluen from LyondellBasell, ExxonMobil PP from ExxonMobil, Formolene® from Formosa Plastics, Borealis PP from Borealis, SEETEC PP from LG Chemical, ASI POLYPROPYLENE from A. Schulman, INEOS PP from INEOS Olefins & Polymers, Braskem PP from Braskem, Samsung Total from SAMSUNG TOTAL PETROCHEMICALS, Sabic® PP from Sabic, TOTAL PETROCHEMICALS Polypropylene from TOTAL PETROCHEMICALS, and YUPLENE® from SK.

[0018] Examples of ethylene polymers include high density polyethylene, low density polyethylene, and linear low density polyethylene. The density of the ethylene polymer measured according to JIS K 7112 is 0.910 g / cm 3 More than 1.00g / cm 3 The following is preferred from the viewpoint of achieving both mechanical strength and rubber elasticity. The melt flow rate of the ethylene polymer (JIS K 7210, 190°C, 21.2N load) is not particularly limited, but is usually 0.05 to 200g / 10min, preferably 0.05 to 100g / 10min, and more preferably 0.1 to 80g / 10min. By controlling the melt flow rate within the above range, excellent moldability and good appearance of the obtained molded product can be obtained, and mechanical properties, particularly tensile breaking strength, can be controlled within a desired range.

[0019] The molecular weight of the propylene-based polymer and the ethylene-based polymer is not particularly limited, but it is preferable that the polymer contains a resin having a weight average molecular weight of 500 to 1,500,000 as measured by gel permeation chromatography (GPC), more preferably 1,000 to 1,000,000, and further preferably 2,000 to 500,000.

[0020] Examples of olefin copolymer rubbers include ethylene-propylene copolymer rubber (EPM), ethylene-propylene-non-conjugated diene copolymer rubber (EPDM), ethylene-butene copolymer rubber (EBM), ethylene-octene copolymer rubber, ethylene-propylene-butene copolymer rubber, etc. These may be used alone or in combination of two or more.

[0021] For olefin copolymer rubber, Mooney viscosity ML 1+4 Ethylene-propylene copolymer rubbers having a Mooney viscosity (ML) (125°C) of 30 to 300 are more preferred, and ethylene-propylene-non-conjugated diene copolymer rubbers (EPDM) are particularly preferred. The EPDM may be an oil-extended type that contains oil in advance, or a non-oil-extended type that does not contain oil, or a combination of these. Non-oil-extended EPDMs that do not contain oil in advance are economically inexpensive. On the other hand, oil-extended EPDMs tend to improve mechanical properties and moldability. As described above, for any type of EPDM, the Mooney viscosity (ML) when containing oil is 1+4 It is suitable to use the film at a temperature of 30 to 100°C (125°C), particularly 35 to 80°C.

[0022] Examples of the non-conjugated diene include dicyclopentadiene, 1,4-hexadiene, cyclooctadiene, methylenenorbornene, ethylidenenorbornene, etc. As the non-conjugated diene, ethylidenenorbornene is particularly preferred.

[0023] A preferred example of the olefin copolymer rubber is EPDM having an ethylene unit content of 55 to 75 mass% and a non-conjugated diene unit content of 1 to 10 mass%. By making the ethylene unit content 55 mass% or more, it is easy to improve extrusion moldability, and by making it 75 mass% or less, it is easy to maintain flexibility.

[0024] As such an olefin copolymer rubber, a commercially available product can be used. Specific examples of commercially available products include "EP Rubber" manufactured by ENEOS Materials, "Mitsui EPT" manufactured by Mitsui Chemicals, Inc., "Esprene (registered trademark)" manufactured by Sumitomo Chemical Co., Ltd., "Keltan (registered trademark)" and "Keltan (registered trademark) Eco" manufactured by ARLANXEO, "NORDEL (registered trademark)" manufactured by Dow Chemical, and "KEP" manufactured by Kumho Polychem.

[0025] The olefin copolymer rubber may be crosslinked with a crosslinking agent from the viewpoint of improving heat resistance and rubber elasticity.

[0026] Examples of the crosslinking agent include organic peroxides, phenol resins, and other crosslinking agents. A crosslinking assistant may be used in combination.

[0027] Specific examples of organic peroxides include dialkyl peroxides such as di-t-butyl peroxide, t-butylcumyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, 2,5-dimethyl-2,5-di(t-butylperoxy)hexyne-3, 1,3-bis(t-butylperoxyisopropyl)benzene, and 1,1-di(t-butylperoxy)-3,3,5-trimethylcyclohexane; t-butylperoxybenzoate, t-butylperoxy-2-ethylhexanoate, t-butylperoxyisopropyl carbonate, and 2,5-dimethylperoxyisopropyl carbonate. peroxides such as acetyl peroxide, lauroyl peroxide, benzoyl peroxide, p-chlorobenzoyl peroxide, 2,4-dichlorobenzoyl peroxide; diacyl peroxides such as di-3,5,5-trimethylhexanoyl peroxide, octanoyl peroxide, dibenzoyl peroxide; and ketone peroxides such as methyl ethyl ketone peroxide and cyclohexanone peroxide.

[0028] For example, phenolic resin crosslinking agents are usually used together with an activator. Examples of activators that can be used here include halogen donors such as stannous chloride, ferric chloride, chlorinated paraffin, chlorinated polyethylene, and chlorosulfonated polyethylene, and acid acceptors such as iron oxide, titanium oxide, magnesium oxide, silicon dioxide, and zinc oxide. When the phenolic resin is halogenated, no halogen donor is required.

[0029] By using the above-mentioned crosslinking agent, it is possible to obtain a partially crosslinked olefin copolymer rubber or a completely crosslinked olefin copolymer rubber. Among them, from the viewpoint of moldability, the partially crosslinked olefin copolymer rubber is preferable.

[0030] Examples of the crosslinking aid include peroxide aids such as sulfur, p-quinone dioxime, p-dinitrosobenzene, and 1,3-diphenylguanidine; crosslinking aids for phenolic resins such as stannous chloride anhydride, stannous chloride dihydrate, and ferric chloride; polyfunctional vinyl compounds such as divinylbenzene, triallyl cyanurate, triallyl isocyanurate, and diallyl phthalate; and polyfunctional (meth)acrylate compounds such as ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, and allyl (meth)acrylate. In this specification, "(meth)acrylate" refers to both "acrylate" and "methacrylate."

[0031] When a crosslinking agent is used, it is preferable to use an organic peroxide from the viewpoint of moldability, and it is preferable to use a polyfunctional vinyl compound or a polyfunctional (meth)acrylate compound in combination as a crosslinking assistant from the viewpoint of ensuring rubber elasticity.

[0032] The olefin-based thermoplastic elastomer composition (A1) may contain a hydrocarbon-based softener for rubber from the viewpoint of improving the processability and flowability of the composition.

[0033] Examples of rubber hydrocarbon-based softeners include mineral oil-based softeners and synthetic resin-based softeners, and mineral oil-based softeners are particularly preferred. Mineral oil-based softeners are generally mixtures of aromatic hydrocarbons, naphthenic hydrocarbons, and paraffinic hydrocarbons, and those in which 50% or more of the total carbon atoms are paraffinic hydrocarbons are called paraffinic oils, those in which 30-45% of the total carbon atoms are naphthenic hydrocarbons, and those in which 35% or more of the total carbon atoms are aromatic hydrocarbons are called aromatic oils. Among these, paraffinic oils are preferred.

[0034] The kinetic viscosity of the hydrocarbon-based rubber softener at 40°C is preferably 20 centistokes (cSt) or more, more preferably 50 cSt or more, while it is preferably 800 cSt or less, more preferably 600 cSt or less.The flash point (COC method) of the hydrocarbon-based rubber softener is preferably 200°C or more, more preferably 250°C or more.

[0035] The rubber hydrocarbon softener may be a commercially available product, such as the "Nippon Oil Polybutene (registered trademark) HV" series manufactured by ENEOS Corporation, the "Diana (registered trademark) Process Oil PW" series manufactured by Idemitsu Kosan Co., Ltd., and the "VIVA-B-FIX" (registered trademark) series manufactured by H&R Co., Ltd., from which an appropriate product may be selected and used.

[0036] The hydrocarbon-based rubber softeners may be used alone or in any combination and ratio of two or more kinds.

[0037] As the olefin-based thermoplastic elastomer composition (A1), commercially available products can be used, such as Milastomer (registered trademark) manufactured by Mitsui Chemicals, Inc., Esporex (registered trademark) TPE series manufactured by Sumitomo Chemical Co., Ltd., Thermorun (registered trademark) manufactured by Mitsubishi Chemical Corporation, Trexprene (registered trademark) manufactured by Mitsubishi Chemical Corporation, Tefablock (registered trademark) manufactured by Mitsubishi Chemical Corporation, Actimer (registered trademark) manufactured by Riken Technos Corporation, Arbus (registered trademark) manufactured by Aronkasei Co., Ltd., Santoprene (registered trademark) manufactured by Celanese, Sarlink (registered trademark) manufactured by Toyobo MC Co., Ltd., and Dawnprene (registered trademark) manufactured by Shandong Dawn Polymer Co., Ltd., etc.

[0038] The Duro A hardness of the olefin-based thermoplastic elastomer composition (A1) is preferably 80 or less, more preferably 30 to 79, and even more preferably 35 to 77, from the viewpoint of flexibility. Within the above range, a composition having high flexibility can be obtained. The measurement methods thereof will be described later.

[0039] [Content ratio] In the olefin-based thermoplastic elastomer composition (A1), the lower limit of the content of the crystalline polyolefin is preferably 3% by mass or more, more preferably 5% by mass or more, even more preferably 7% by mass or more, and particularly preferably 10% by mass or more, based on 100% by mass of the total of the crystalline polyolefin, the olefin-based copolymer rubber, and the hydrocarbon-based softener for rubber, from the viewpoints of stable moldability, heat resistance, and other mechanical properties. On the other hand, the upper limit of the content of the crystalline polyolefin is preferably 95% by mass or less, more preferably 90% by mass or less, even more preferably 85% by mass or less, and particularly preferably 80% by mass or less, from the viewpoints of stable rubber elasticity and good moldability.

[0040] In the olefin-based thermoplastic elastomer composition (A1), the lower limit of the content of the olefin-based copolymer rubber is preferably 3% by mass or more, more preferably 5% by mass or more, even more preferably 10% by mass or more, and particularly preferably 15% by mass or more, based on 100% by mass of the total of the crystalline polyolefin, the olefin-based copolymer rubber, and the hydrocarbon-based softener for rubber, from the viewpoint of stable rubber elasticity and good moldability. On the other hand, the upper limit of the content of the olefin-based copolymer rubber is preferably 90% by mass or less, more preferably 80% by mass or less, even more preferably 70% by mass or less, and particularly preferably 60% by mass or less, from the viewpoint of stable processability, moldability, heat resistance, and other mechanical properties.

[0041] When the olefin-based thermoplastic elastomer composition (A1) contains the above-mentioned rubber hydrocarbon-based softener, the content of the rubber hydrocarbon-based softener is preferably 10 parts by mass or more, more preferably 20 parts by mass or more, even more preferably 30 parts by mass or more, and particularly preferably 40 parts by mass or more, relative to 100 parts by mass of the olefin-based copolymer rubber, from the viewpoints of weight reduction, stable rubber elasticity, and good moldability. On the other hand, the upper limit of the content of the rubber hydrocarbon-based softener is preferably 400 parts by mass or less, more preferably 350 parts by mass or less, even more preferably 300 parts by mass or less, and particularly preferably 200 parts by mass or less, relative to 100 parts by mass of the olefin-based copolymer rubber, from the viewpoints of handleability during production and bleed-out resistance.

[0042] [Other ingredients] In addition to the above-mentioned components, other components may be blended into the olefin-based thermoplastic elastomer composition (A1) as necessary within the range that does not impair the effects of the present invention.

[0043] Examples of other components include thermoplastic resins other than crystalline polyolefins, rubbers other than olefin copolymer rubbers, fillers, heat stabilizers (also called antioxidants), light stabilizers, ultraviolet absorbers, neutralizers, lubricants, antifogging agents, antiblocking agents, slipping agents, dispersants, colorants, antistatic agents, conductivity imparting agents, metal deactivators, molecular weight regulators, antibacterial agents, antifungal agents, fluorescent whitening agents, and other various additives, which may be blended within a range that does not impair the effects of the present invention. Any of these may be used alone or in combination.

[0044] Examples of thermoplastic resins other than crystalline polyolefins include polyphenylene ether resins; polyamide resins such as nylon 6 and nylon 66; polyester resins such as polyethylene terephthalate and polybutylene terephthalate; polyoxymethylene resins such as polyoxymethylene homopolymers and polyoxymethylene copolymers; and polymethyl methacrylate resins. Examples of rubbers other than olefin copolymer rubbers include styrene rubbers, polyester elastomers, and polybutadiene. These thermoplastic resins other than crystalline polyolefins and rubbers other than olefin copolymer rubbers may be used alone or in combination of two or more.

[0045] Examples of the filler include glass fiber, hollow glass spheres, carbon fiber, alumina, talc, calcium carbonate, clay, mica, potassium titanate fiber, silica, zeolite, metal soap, calcium carbonate, titanium dioxide, carbon black, boron nitride, and cellulose. These fillers may be used alone, or two or more of them may be used in any combination and in any ratio.

[0046] Examples of heat stabilizers (antioxidants) that can be used include aliphatic, aromatic, or alkyl group-substituted aromatic esters of phosphoric acid and phosphorous acid, hypophosphorous acid derivatives, phosphorus compounds such as phenylphosphonic acid, phenylphosphinic acid, diphenylphosphonic acid, polyphosphonates, dialkyl pentaerythritol diphosphite, and dialkyl bisphenol A diphosphite; phenol derivatives, particularly hindered phenol compounds; sulfur-containing compounds such as thioethers, dithioacid salts, mercaptobenzimidazoles, thiocarbanilides, and thiodipropionates; and tin compounds such as tin maleates and dibutyltin monoxide. These heat stabilizers (antioxidants) may be used alone or in combination of two or more.

[0047] Examples of the hindered phenol compound include "Irganox (registered trademark) 1010" and "Irganox (registered trademark) 1520" (both trade names, manufactured by BASF Japan Ltd.). Examples of phosphorus compounds include "PEP-36", "PEP-24G", and "HP-10" (all trade names manufactured by ADEKA CORPORATION), and "Irgafos (registered trademark) 168" (trade name manufactured by BASF Japan Ltd.).

[0048] Examples of the sulfur-containing compound include thioether compounds such as dilauryl thiopropionate (DLTP) and distearyl thiopropionate (DSTP).

[0049] Examples of light stabilizers include benzotriazole-based and benzophenone-based compounds. Specifically, "TINUVIN622LD" and "TINUVIN765" (all trade names: manufactured by BASF Japan Ltd.), "SANOLLS-2626" and "SANOLLS-765" (all trade names: manufactured by Sankyo Co., Ltd.) can be used, and one type may be used alone, or two or more types may be used in combination.

[0050] Examples of the ultraviolet absorbing agent include "TINUVIN328" and "TINUVIN234" (both trade names, manufactured by BASF Japan Ltd.), and one type may be used alone, or two or more types may be used in combination.

[0051] Examples of the lubricant include fatty acid amides, fatty acid metal salts, and organopolysiloxanes. One type may be used alone, or two or more types may be used in combination.

[0052] Examples of colorants include dyes such as direct dyes, acid dyes, basic dyes, and metal complex dyes; inorganic pigments such as carbon black, titanium oxide, zinc oxide, iron oxide, and mica; and organic pigments such as coupling azo pigments, condensed azo pigments, anthraquinone pigments, thioindigo pigments, dioxazone pigments, and phthalocyanine pigments. One type may be used alone, or two or more types may be used in combination.

[0053] [Styrene-based thermoplastic elastomer composition (A2)] The thermoplastic elastomer composition (II) contains a styrene-based thermoplastic elastomer composition (A2). The styrene-based thermoplastic elastomer composition (A2) is preferably a composition containing a styrene-based rubber.

[0054] As the styrene-based rubber, a block copolymer and / or a hydrogenated product thereof (hereinafter also referred to as "(hydrogenated) block copolymer") having a polymer block P (hereinafter also referred to as "block P") mainly composed of at least one aromatic vinyl compound unit and a polymer block Q (hereinafter also referred to as "block Q") mainly composed of at least one conjugated diene compound unit is preferable. Here, the term "mainly composed of" means that the content of the monomer units constituting the block is 50 mol % or more.

[0055] The aromatic vinyl compound constituting the block P is not particularly limited, and examples thereof include styrene, α-substituted styrenes such as α-methylstyrene, α-ethylstyrene, and α-methyl-p-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, 2,4-dimethylstyrene, 2,4,6-trimethylstyrene, ethylstyrene, ot-butylstyrene, pt-butylstyrene, divinylbenzene, 1,1-diphenylethylene, N,N-dimethyl-p-aminoethylstyrene, and N,N-diethyl-p-aminoethylstyrene. Among these, from the viewpoints of availability and productivity, styrene, α-methylstyrene, and p-methylstyrene are preferred, and styrene is more preferred. The block P may be composed of one type of aromatic vinyl compound unit or two or more types of aromatic vinyl compound units. The block P may contain a monomer unit other than the aromatic vinyl compound unit.

[0056] The conjugated diene compound constituting the block Q is a diolefin having a pair of conjugated double bonds, and examples thereof include, but are not limited to, 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 2-methyl-1,3-pentadiene, and 1,3-hexadiene. Among these, from the viewpoint of productivity, 1,3-butadiene and isoprene are preferred, and 1,3-butadiene is more preferred. The block Q may be composed of one type of conjugated diene compound unit or may be composed of two or more types of conjugated diene compound units. The block Q may contain a monomer unit other than the conjugated diene compound unit.

[0057] As such a (hydrogenated) styrene-based rubber, a commercially available product can also be used. Specific examples of commercially available products include "KRATON (registered trademark) G" manufactured by Kraton Polymers, "SEPTON (registered trademark)," "SEPTON (registered trademark) Bio," and "HYBLER (registered trademark)" manufactured by Kuraray Co., Ltd., "TUFTECH (registered trademark)" and "SOE (registered trademark)" manufactured by Asahi Kasei Corporation, "DYNARON (registered trademark)" manufactured by ENEOS Materials, Inc., "TAIPOL (registered trademark)" manufactured by Oxali Chemicals, Inc., and "GLOBALPRENE" manufactured by LCY Corporation.

[0058] The styrene-based thermoplastic elastomer composition (A2) may contain a crystalline polyolefin from the viewpoint of improving heat resistance and flowability. As the crystalline polyolefin, those exemplified in the above (A1) can be used. The styrene-based thermoplastic elastomer composition (A2) may contain a rubber hydrocarbon softener from the viewpoint of improving fluidity. As the rubber hydrocarbon softener, those exemplified in (A1) above can be used.

[0059] As such a styrene-based thermoplastic elastomer composition (A2), commercially available products can be used, such as TEFABLOC (registered trademark) manufactured by Mitsubishi Chemical Corporation, LEOSTOMER (registered trademark) manufactured by RIKEN TECHNOS CORPORATION, ELASTOMER AR (registered trademark) manufactured by ARON KASEI CORPORATION, ALLOSTOMER (registered trademark) manufactured by ARON KASEI CORPORATION, ARNESTON (registered trademark) manufactured by KURARAY PLASTS CO., LTD., and THERMOLAST (registered trademark) manufactured by KRAIBURG TPE GMBH & CO.KG.

[0060] From the viewpoint of flexibility, the Duro A hardness of the styrene-based thermoplastic elastomer composition (A2) is preferably 80 or less, more preferably 5 to 79, and even more preferably 10 to 77. Within this range, a composition with high flexibility can be obtained. The measurement methods thereof will be described later.

[0061] [Content ratio] In the styrene-based thermoplastic elastomer composition (A2), the lower limit of the content of the crystalline polyolefin is preferably 1% by mass or more, more preferably 2% by mass or more, even more preferably 3% by mass or more, even more preferably 5% by mass or more, and particularly preferably 10% by mass or more, based on 100% by mass of the total of the crystalline polyolefin, the (hydrogenated) styrene-based rubber, and the hydrocarbon-based softener for rubber, from the viewpoints of stable moldability, heat resistance, and other mechanical properties. On the other hand, the upper limit of the content of the crystalline polyolefin is preferably 95% by mass or less, more preferably 90% by mass or less, even more preferably 85% by mass or less, and particularly preferably 80% by mass or less, from the viewpoints of stable rubber elasticity and good moldability.

[0062] In the styrene-based thermoplastic elastomer composition (A2), the lower limit of the content of the (hydrogenated) styrene-based rubber is preferably 3% by mass or more, more preferably 5% by mass or more, even more preferably 10% by mass or more, and particularly preferably 15% by mass or more, based on 100% by mass of the total of the crystalline polyolefin, the (hydrogenated) styrene-based rubber, and the hydrocarbon-based softener for rubber, from the viewpoint of stable rubber elasticity and good moldability. On the other hand, the upper limit of the content of the (hydrogenated) styrene-based rubber is preferably 90% by mass or less, more preferably 80% by mass or less, even more preferably 70% by mass or less, and particularly preferably 60% by mass or less, from the viewpoint of stable processability, moldability, heat resistance, and other mechanical properties.

[0063] When the styrene-based thermoplastic elastomer composition (A2) contains the above-mentioned rubber hydrocarbon-based softener, the content of the rubber hydrocarbon-based softener is preferably 10 parts by mass or more, more preferably 20 parts by mass or more, even more preferably 30 parts by mass or more, and particularly preferably 40 parts by mass or more, relative to 100 parts by mass of the (hydrogenated) styrene-based rubber, from the viewpoints of weight reduction, stable rubber elasticity, and good moldability. On the other hand, the upper limit of the content of the rubber hydrocarbon-based softener is preferably 400 parts by mass or less, more preferably 350 parts by mass or less, even more preferably 300 parts by mass or less, and particularly preferably 200 parts by mass or less, relative to 100 parts by mass of the (hydrogenated) styrene-based rubber, from the viewpoints of handleability during production and bleed-out resistance.

[0064] [Other ingredients] The styrene-based thermoplastic elastomer composition (A2) may contain other components as required, provided that the effects of the present invention are not impaired.

[0065] As other components, for example, thermoplastic resins other than the above-mentioned crystalline polyolefins and rubbers other than the above-mentioned (hydrogenated) styrene copolymer rubbers can be blended. Further examples of additives that can be used include fillers, heat stabilizers (also referred to as antioxidants), light stabilizers, ultraviolet absorbers, neutralizing agents, lubricants, antifogging agents, antiblocking agents, slip agents, dispersants, colorants, antistatic agents, conductivity imparting agents, metal deactivators, molecular weight regulators, antibacterial agents, antifungal agents, and fluorescent brightening agents. These are the same as those described above as additives that can be incorporated into the olefin-based thermoplastic elastomer composition (A1). The above-mentioned other components can be blended within the range that does not impair the effects of the present invention, and any of the components can be used alone or in combination.

[0066] The ratio of the olefin-based thermoplastic elastomer composition (A1) to the total mass of the thermoplastic elastomer composition (I) and the ratio of the styrene-based thermoplastic elastomer composition (A2) to the total mass of the thermoplastic elastomer composition (II) are preferably 20% by mass or more, more preferably 30% by mass or more, even more preferably 40% by mass or more, even more preferably 45% by mass or more, and particularly preferably 50% by mass or more, and are preferably 80% by mass or less, more preferably 70% by mass or less, and even more preferably less than 60% by mass. If the ratio of the olefin-based thermoplastic elastomer composition (A1) or the styrene-based thermoplastic elastomer composition (A2) is equal to or more than the lower limit, the inherent physical properties of the respective thermoplastic elastomer compositions (A1) and (A2) are easily exhibited, and if it is equal to or less than the upper limit, the flame retardancy is more excellent.

[0067] The ratio of the olefin-based thermoplastic elastomer composition (A1) to the total mass of the thermoplastic elastomer composition (I) and the ratio of the styrene-based thermoplastic elastomer composition (A2) to the total mass of the thermoplastic elastomer composition (II) may be, for example, from 20 mass% to 80 mass%, from 30 mass% to 70 mass%, from 40 mass% to 70 mass%, from 45 mass% to less than 60 mass%, or from 50 mass% to less than 60 mass%, respectively.

[0068] [Phosphorus-based flame retardants (B)] The phosphorus-based flame retardant (B) is a phosphorus compound, i.e., a compound containing a phosphorus atom in the molecule. The phosphorus-based flame retardant (B) exerts a flame retardant effect by forming char when the thermoplastic elastomer compositions (I) and (II) are combusted. As the phosphorus-based flame retardant (B), known ones can be used, for example, (poly)phosphates, (poly)phosphate esters, etc. "(Poly)phosphates" refers to phosphates or polyphosphates. "(Poly)phosphate esters" refers to phosphate esters or polyphosphate esters. The phosphorus-based flame retardant (B) is preferably a solid at 80°C.

[0069] As the phosphorus-based flame retardant (B), a (poly)phosphate is preferred from the standpoint of flame retardancy. Examples of (poly)phosphates include ammonium polyphosphate, melamine polyphosphate, piperazine polyphosphate, piperazine orthophosphate, melamine pyrophosphate, piperazine pyrophosphate, melamine polyphosphate, melamine orthophosphate, calcium phosphate, and magnesium phosphate. The phosphorus-based flame retardant (B) preferably contains a compound having a melamine structure or a piperazine structure.

[0070] In addition, in the above examples, compounds in which melamine or piperazine is replaced with other nitrogen compounds can be used in the same manner. Examples of other nitrogen compounds include N,N,N',N'-tetramethyldiaminomethane, ethylenediamine, N,N'-dimethylethylenediamine, N,N'-diethylethylenediamine, N,N-dimethylethylenediamine, N,N-diethylethylenediamine, N,N,N',N'-tetramethylethylenediamine, N,N,N',N'-tetraethylethylenediamine, 1,2-propanediamine, 1,3-propanediamine, tetraethylethylenediamine, tetramethylethylenediamine, tetraethyl ... Tramethylenediamine, pentamethylenediamine, hexamethylenediamine, 1,7-diaminoheptane, 1,8-diaminooctane, 1,9-diaminononane, 1,10-diaminodecane, trans-2,5-dimethylpiperazine, 1,4-bis(2-aminoethyl)piperazine, 1,4-bis(3-aminopropyl)piperazine, acetoguanamine, benzoguanamine, acrylguanamine, 2,4-diamino-6-nonyl-1, 3,5-triazine, 2,4-diamino-6-hydroxy-1,3,5-triazine, 2-amino-4,6-dihydroxy-1,3,5-triazine, 2,4-diamino-6-methoxy-1,3,5-triazine, 2,4-diamino-6-ethoxy-1,3,5-triazine, 2,4-diamino-6-propoxy-1,3,5-triazine, 2,4-diamino-6-isopropoxy-1,3,5-triazine, 2,4-diamino-6 -mercapto-1,3,5-triazine, 2-amino-4,6-dimercapto-1,3,5-triazine, ammeline, benzguanamine, acetoguanamine, phthalodiguanamine, melamine cyanurate, butylenediguanamine, norbornenediguanamine, methylenediguanamine, ethylenedimelamine, trimethylenedimelamine, tetramethylenedimelamine, hexamethylenedimelamine, and 1,3-hexylenedimelamine.

[0071] These (poly)phosphates may be used alone or in combination of two or more.

[0072] Among them, it is preferable that the phosphorus-based flame retardant (B) is a salt of (poly)phosphoric acid and a nitrogen compound (hereinafter also referred to as "compound (B1)"). The compound (B1) corresponds to an intumescent flame retardant, and expands during combustion of the thermoplastic elastomer compositions (I) and (II) to form a surface expansion layer (intemescent) which is char. The formation of the surface expansion layer suppresses heat transfer, and excellent flame retardancy is exhibited. Examples of the nitrogen compound in the compound (B1) include ammonia, melamine, piperazine, and the other nitrogen compounds described above.

[0073] Commercially available phosphorus-based flame retardants (B) include, for example, Adeka STAB FP-2100J, FP-2200, and FP-2500S (manufactured by ADEKA CORPORATION).

[0074] In the present thermoplastic elastomer composition (I) and the present thermoplastic elastomer composition (II), the ratio of the phosphorus-based flame retardant (B) is 5 to 400 parts by mass relative to 100 parts by mass of the olefin-based thermoplastic elastomer composition (A1) of the present thermoplastic elastomer composition (I) and 100 parts by mass of the styrene-based thermoplastic elastomer composition (A2) of the present thermoplastic elastomer composition (II). By setting the ratio of the phosphorus-based flame retardant (B) relative to the olefin-based thermoplastic elastomer composition (A1) and the styrene-based thermoplastic elastomer composition (A2) within the above range, when used in combination with the copolymer (C) of α-olefin and unsaturated carboxylic acid described below, a significant decrease in mechanical properties can be prevented and high flame retardancy can be obtained.

[0075] In particular, the ratio of the phosphorus-based flame retardant (B) per 100 parts by mass of each of the olefin-based thermoplastic elastomer composition (A1) and the styrene-based thermoplastic elastomer composition (A2) is preferably 30 parts by mass or more, more preferably 40 parts by mass or more, even more preferably 50 parts by mass or more, still more preferably 60 parts by mass or more, and particularly preferably 68 parts by mass or more, while being preferably 300 parts by mass or less, more preferably 250 parts by mass or less, even more preferably 200 parts by mass or less, still more preferably 150 parts by mass or less, still more preferably 100 parts by mass or less, and still more preferably 90 parts by mass or less. The ratio of the phosphorus-based flame retardant (B) per 100 parts by mass of each of the olefin-based thermoplastic elastomer composition (A1) and the styrene-based thermoplastic elastomer composition (A2) may be, for example, 30 to 300 parts by mass, 40 to 250 parts by mass, 50 to 200 parts by mass, 60 to 150 parts by mass, 68 to 100 parts by mass, or 68 to 90 parts by mass.

[0076] The ratio of the phosphorus-based flame retardant (B) to the total mass of each of the thermoplastic elastomer composition (I) and the thermoplastic elastomer composition (II) is preferably 35% by mass or more, more preferably 38% by mass or more, and even more preferably 40% by mass or more, and is preferably 50% by mass or less, more preferably 48% by mass or less, and even more preferably 45% by mass or less. If the ratio of the phosphorus-based flame retardant (B) is equal to or more than the lower limit, the flame retardancy is excellent, and if it is equal to or less than the upper limit, the inherent physical properties (e.g., high mechanical properties and flexibility) of the olefin-based thermoplastic elastomer composition (A1) contained in the thermoplastic elastomer composition (I) and the styrene-based thermoplastic elastomer composition (A2) contained in the thermoplastic elastomer composition (II) are easily expressed. The proportion of the phosphorus-based flame retardant (B) relative to the total mass of the thermoplastic elastomer composition (I) and / or the thermoplastic elastomer composition (II) may be, for example, 35 to 50 mass%, 38 to 48 mass%, or 40 to 45 mass%.

[0077] [Copolymer of α-olefin and unsaturated carboxylic acid (C)] The copolymer (C) enhances the dispersibility of the phosphorus-based flame retardant (B) in the olefin-based thermoplastic elastomer composition (A1) and the styrene-based thermoplastic elastomer composition (A2). In the present invention, the "copolymer (C) of an α-olefin and an unsaturated carboxylic acid" means a copolymer in which the ratio of α-olefin units to the total of 100 mol % of α-olefin units and unsaturated carboxylic acid units is 20 to 80 mol %. In the copolymer (C), the ratio of the α-olefin units to the total of 100 mol% of the α-olefin units and the unsaturated carboxylic acid units is preferably 30 mol% or more, and preferably 70 mol% or less. If the ratio of the α-olefin units is not less than the lower limit, the compatibility with the olefin-based thermoplastic elastomer composition (A1) and the styrene-based thermoplastic elastomer composition (A2) is excellent, and if it is not more than the upper limit, the compatibility with the phosphorus-based flame retardant (B) is excellent.

[0078] In the copolymer (C), the α-olefin is preferably an α-olefin having 10 to 80 carbon atoms. If the α-olefin has 10 or more carbon atoms, the compatibility with the olefin-based thermoplastic elastomer composition (A1) and the styrene-based thermoplastic elastomer composition (A2) tends to be better. On the other hand, if the α-olefin has 80 or less carbon atoms, it tends to be more advantageous in terms of raw material costs. The number of carbon atoms of the α-olefin is more preferably 12 to 70, and even more preferably 18 to 60.

[0079] In the copolymer (C), examples of the unsaturated carboxylic acid include (meth)acrylic acid, maleic acid, methylmaleic acid, fumaric acid, methylfumaric acid, tetrahydrophthalic acid, itaconic acid, citraconic acid, crotonic acid, isocrotonic acid, glutaconic acid, norbornane-5-ene-2,3-dicarboxylic acid, and esters, anhydrides, imides, etc. of these unsaturated carboxylic acids. "(Meth)acrylic acid" refers to acrylic acid or methacrylic acid. Specific examples of the ester, anhydride or imide of an unsaturated carboxylic acid include (meth)acrylic acid esters such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and glycidyl (meth)acrylate; dicarboxylic acid anhydrides such as maleic anhydride, itaconic anhydride, citraconic anhydride, and 5-norbornene-2,3-dicarboxylic acid anhydride; and maleimide compounds such as maleimide, N-ethylmaleimide, and N-phenylmaleimide. These may be used alone or in combination of two or more.

[0080] Among the above, esters and dicarboxylic anhydrides are preferred from the viewpoint of copolymerization reactivity, and among these, dicarboxylic anhydrides are preferred from the viewpoint of compatibility with the phosphorus-based flame retardant (B), with maleic anhydride being particularly preferred.

[0081] The weight average molecular weight of the copolymer (C) is preferably 2,000 or more, more preferably 3,000 or more, and even more preferably 5,000 or more, and is preferably 50,000 or less, more preferably 30,000 or less, and even more preferably 10,000 or less. When the weight average molecular weight of the copolymer (C) is within the above upper and lower limit ranges, the dispersibility of the phosphorus-based flame retardant (B) is further improved. The weight average molecular weight of the copolymer (C) may be, for example, 2,000 to 50,000, 3,000 to 30,000, or 5,000 to 10,000. The weight average molecular weight of the copolymer (C) is a value calculated as standard polystyrene by dissolving the copolymer (C) in tetrahydrofuran (THF) and measuring the molecular weight by gel permeation chromatography.

[0082] Commercially available copolymers (C) include, for example, Lycorb CE2 (manufactured by Clariant Japan KK) and Diacalna 30M (manufactured by Mitsubishi Chemical Corporation).

[0083] As described above, the thermoplastic elastomer composition (I) and the thermoplastic elastomer composition (II) contain the copolymer (C), and the ratio of the copolymer (C) to the phosphorus-based flame retardant (B) (100 mass%) is preferably 10 mass% or less. In particular, the proportion of the copolymer (C) relative to the phosphorus-based flame retardant (B) (100% by mass) is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, even more preferably 0.1% by mass or more, still more preferably 0.5% by mass or more, even more preferably 1% by mass or more, particularly preferably 3% by mass or more, while more preferably 8% by mass or less, still more preferably 7% by mass or less, still more preferably 6% by mass or less, particularly preferably 5% by mass or less. By using the copolymer (C) in a ratio relative to the phosphorus-based flame retardant (B) (100% by mass) within the above range, it is possible to obtain a molded article having high flame retardancy while maintaining excellent mechanical strength and flexibility.

[0084] In the present thermoplastic elastomer composition (I) and the present thermoplastic elastomer composition (II), the ratio of the copolymer (C) to the phosphorus-based flame retardant (B) (100 mass%) may be, for example, 0.01 to 8 mass%, may be 0.05 to 8 mass%, may be 0.1 to 7 mass%, may be 0.1 to 6 mass%, may be 0.5 to 6 mass%, may be 1 to 6 mass%, or may be 3 to 5 mass%.

[0085] The proportion of copolymer (C) relative to the total mass of each of the thermoplastic elastomer composition (I) and the thermoplastic elastomer composition (II) is preferably 0.01 mass% or more, more preferably 0.03 mass% or more, even more preferably 0.1 mass% or more, still more preferably 0.5 mass% or more, and particularly preferably 1 mass% or more, while being preferably 10 mass% or less, more preferably 5 mass% or less, and even more preferably 3 mass% or less. When the proportion of copolymer (C) is equal to or greater than the lower limit, phosphorus-based flame retardant (B) is well dispersed, and the flame retardancy, high flexibility, mechanical properties, and appearance of the resulting molded article of thermoplastic elastomer compositions (I and II) are improved. When the proportion of copolymer (C) is equal to or less than the upper limit, the influence of copolymer (C) on the flame retardancy of thermoplastic elastomer compositions (I and II) can be suppressed. The ratio of copolymer (C) to the total mass of each of the thermoplastic elastomer composition (I) and the thermoplastic elastomer composition (II) may be, for example, 0.01 to 10 mass%, 0.03 to 5 mass%, 0.1 to 3 mass%, 0.5 to 3 mass%, or 1 to 3 mass%.

[0086] The ratio of the copolymer (C) to the total mass of the olefin-based thermoplastic elastomer composition (A1) and the phosphorus-based flame retardant (B) in the thermoplastic elastomer composition (I) and / or the ratio of the copolymer (C) to the total mass of the styrene-based thermoplastic elastomer composition (A2) and the phosphorus-based flame retardant (B) in the thermoplastic elastomer composition (II) is preferably 0.01 mass% or more, more preferably 0.05 mass% or more, even more preferably 0.1 mass% or more, still more preferably 0.5 mass% or more, particularly preferably 1 mass% or more, while being preferably 5 mass% or less, more preferably 4 mass% or less, even more preferably 3 mass% or less, and still more preferably 2.5 mass% or less. When the proportion of copolymer (C) is equal to or greater than the lower limit, the phosphorus-based flame retardant (B) is more favorably dispersed, and the flame retardancy, high flexibility, mechanical properties, and appearance of the resulting molded article of the thermoplastic elastomer compositions (I and II) are improved. When the proportion of copolymer (C) is equal to or less than the upper limit, the effect of copolymer (C) on the flame retardancy of thermoplastic elastomer compositions (I and II) can be more suppressed.

[0087] The ratio of the copolymer (C) to the total mass of the olefin-based thermoplastic elastomer composition (A1) and the phosphorus-based flame retardant (B), and / or the ratio of the copolymer (C) to the total mass of the styrene-based thermoplastic elastomer composition (A2) and the phosphorus-based flame retardant (B) may be, for example, 0.01 to 5 mass%, may be 0.05 to 5 mass%, may be 0.1 to 5 mass%, may be 0.5 to 4 mass%, may be 1 to 3 mass%, or may be 1 to 2.5 mass%.

[0088] The ratio of the total mass of the olefin-based thermoplastic elastomer composition (A1), the phosphorus-based flame retardant (B) and the copolymer (C) to the total mass of the thermoplastic elastomer composition (I) is preferably 60 mass% or more, more preferably 70 mass% or more, even more preferably 80 mass% or more, particularly preferably 90 mass% or more, and may be 100 mass%. The ratio of the total mass of the styrene-based thermoplastic elastomer composition (A2), the phosphorus-based flame retardant (B) and the copolymer (C) to the total mass of the thermoplastic elastomer composition (II) is preferably 60 mass% or more, more preferably 70 mass% or more, even more preferably 80 mass% or more, particularly preferably 90 mass% or more, and may be 100 mass%. For example, when the total mass of the components (A1) or (A2), (B) and (C) in the thermoplastic elastomer compositions (I) and (II) is 100% by mass, the amounts of the olefin-based thermoplastic elastomer composition (A1) or the styrene-based thermoplastic elastomer composition (A2), the phosphorus-based flame retardant (B) and the copolymer (C) can be appropriately selected from the above-mentioned possible ranges so that the total of the three components is 100% by mass.

[0089] <Other flame retardants or flame retardant auxiliaries> As the other flame retardant or flame retardant assistant, a conventionally known bromine-based flame retardant, an antimony-based flame retardant, etc. other than the phosphorus-based flame retardant (B), or an organic or inorganic flame retardant or flame retardant assistant not containing a halogen is preferable. Examples of such flame retardant or flame retardant assistant include at least one selected from the group consisting of a triazine ring-containing compound, a silicone-based flame retardant, a metal hydroxide, a metal oxide, a boric acid compound, and an expandable graphite.

[0090] Examples of the triazine ring-containing compound include melamine, ammeline, benzguanamine, acetoguanamine, phthalodiguanamine, melamine cyanurate, butylenediguanamine, norbornenediguanamine, methylenediguanamine, ethylenedimelamine, trimethylenedimelamine, tetramethylenedimelamine, hexamethylenedimelamine, and 1,3-hexylenedimelamine. Examples of silicone-based flame retardants include silicone oil, silicone rubber, and silicone resin. Examples of metal hydroxides include magnesium hydroxide, aluminum hydroxide, calcium hydroxide, barium hydroxide, zinc hydroxide, Kismer 5A (a trademark of magnesium hydroxide manufactured by Kyowa Chemical Industry Co., Ltd.), and the like. Examples of metal oxides include inorganic compounds such as zinc oxide, titanium oxide, aluminum oxide, magnesium oxide, titanium dioxide, and hydrotalcite, and surface-treated products thereof. Specific examples of metal oxides include TIPAQUE R-680 (trademark of titanium oxide manufactured by Ishihara Sangyo Kaisha), Kyowamag 150 (trademark of magnesium oxide manufactured by Kyowa Chemical Industry Co., Ltd.), DHT-4A (hydrotalcite: manufactured by Kyowa Chemical Industry Co., Ltd.), and Alcamizer 4 (trademark of zinc-modified hydrotalcite manufactured by Kyowa Chemical Industry Co., Ltd.). An example of the boric acid compound is zinc borate. These flame retardants or flame retardant auxiliaries may be used alone or in combination of two or more.

[0091] <Other ingredients> The thermoplastic elastomer composition (I) and the thermoplastic elastomer composition (II) may contain other components within the range not impairing the effects of the present invention. The other components may include at least one selected from the group consisting of inorganic fiber fillers, interfacial strength improvers, heat stabilizers (also called antioxidants), ultraviolet absorbers, light stabilizers, and antiaging agents. For example, the inorganic fiber filler may contain at least one type of inorganic fiber filler selected from the group consisting of glass fiber and carbon fiber, and one type of inorganic fiber filler may be used alone or two or more types may be used in combination. As the interfacial strength improver, a polymer having an olefin skeleton (excluding the olefin-based thermoplastic elastomer composition (A1) and the copolymer (C)) is preferable, particularly from the viewpoint of compatibility with the thermoplastic elastomer composition (A1) or (A2). The interfacial strength is further improved by the compatibility of the olefin skeleton with the thermoplastic elastomer composition (A1) or (A2). Commercially available interfacial strength improvers include, for example, UMEX 1001 and 1010 (manufactured by Sanyo Chemical Industries, Ltd.), and KAYABRID 002PP and 003PP (manufactured by Nouryon Chemical Industry Co., Ltd.).

[0092] Examples of the heat stabilizer (antioxidant) include phenol-based antioxidants, phosphorus-based antioxidants, and thioether-based antioxidants. Examples of ultraviolet absorbers include 2-hydroxybenzophenones, 2-(2'-hydroxyphenyl)benzotriazoles, benzoates, substituted oxanilides, cyanoacrylates, and triaryltriazines. As the light stabilizer, a hindered amine compound can be used.

[0093] In addition to the above, the thermoplastic elastomer composition (I) and the thermoplastic elastomer composition (II) may contain a plasticizer, a fluorine-containing anti-dripping agent, and commonly used additives such as a crosslinking agent, an antistatic agent, a metal soap, a filling agent, an anti-fogging agent, an anti-plateout agent, a surface treatment agent, a fluorescent agent, an anti-fungal agent, a bactericide, a foaming agent, a metal deactivator, a release agent, a pigment, a processing aid, and the like, within the range not impairing the effects of the present invention.

[0094] [Method of producing thermoplastic elastomer composition] Any method may be adopted to produce the present thermoplastic elastomer composition (I) and the present thermoplastic elastomer composition (II). For example, the olefin-based thermoplastic elastomer composition (A1) or the styrene-based thermoplastic elastomer composition (A2), the phosphorus-based flame retardant (B), the copolymer (C), and if necessary, other flame retardants, flame retardant auxiliaries, and other components are thoroughly mixed using a premixing means such as a V-type blender, a Henschel mixer, a mechanochemical device, or an extrusion mixer, and optionally granulated using an extrusion granulator or a briquetting machine, and then melt-kneaded and extruded using a melt mixer.

[0095] Examples of the melt kneader include a twin-screw extruder such as a vented twin-screw extruder, a Banbury mixer, a kneading roll, a single-screw extruder, and a multi-screw extruder having three or more screws. The temperature during melt kneading is, for example, 170 to 260°C. The thermoplastic elastomer composition (I) or (II) extruded as described above is directly cut into pellets by a machine such as a pelletizer, or is cooled to form strands, and the strands are then cut into pellets by a machine such as a pelletizer. That is, in another aspect of this embodiment, pellets containing the thermoplastic elastomer composition (I) or (II) are provided.

[0096] As described in detail, the thermoplastic elastomer composition (I) contains the olefin-based thermoplastic elastomer composition (A1), the phosphorus-based flame retardant (B), and the copolymer (C), and the thermoplastic elastomer composition (II) contains the styrene-based thermoplastic elastomer composition (A2), the phosphorus-based flame retardant (B), and the copolymer (C). Therefore, the thermoplastic elastomer composition (II) can exhibit excellent flame retardancy while fully maintaining the inherent physical properties (e.g., high mechanical properties and flexibility) of the respective thermoplastic elastomer compositions (A1) and (A2). The copolymer (C) improves the dispersibility of the phosphorus-based flame retardant (B) in each of the thermoplastic elastomer compositions (A1) and (A2). It is believed that the improved dispersibility of the phosphorus-based flame retardant (B) makes it easier to form char during combustion, thereby improving flame retardancy. The mechanism behind this is not clear, but the following is thought to be the cause.

[0097] The olefin-based thermoplastic elastomer composition (A1) and the styrene-based thermoplastic elastomer composition (A2) are classified as low-polarity resins among thermoplastic elastomers, and it is difficult to disperse polar additives such as the phosphorus-based flame retardant (B). On the other hand, the copolymer (C) has a low-polarity α-olefin moiety that is highly compatible with the olefin-based thermoplastic elastomer composition (A1) and the styrene-based thermoplastic elastomer composition (A2), and a polar unsaturated carboxylic acid moiety that is highly compatible with the phosphorus-based flame retardant (B). When the thermoplastic elastomer compositions (I) and (II) are melt-kneaded, the presence of the copolymer (C) between the olefin-based thermoplastic elastomer composition (A1) and the styrene-based thermoplastic elastomer composition (A2) and the phosphorus-based flame retardant (B) is thought to improve the dispersibility of the phosphorus-based flame retardant (B) in the thermoplastic elastomer.

[0098] The effects of the copolymer (C) include (1) improving the dispersibility of the phosphorus-based flame retardant (B) (finely dispersing), (2) promoting char generation during combustion, and (3) improving physical properties (tensile strain at break).

[0099] Specifically, as an effect during combustion, when a flat test piece obtained by molding the thermoplastic elastomer composition (I) or (II) containing the olefin-based thermoplastic elastomer composition (A1) or the styrene-based thermoplastic elastomer composition (A2) and the phosphorus-based flame retardant (B) is heated with a burner, small and numerous chars are formed on the surface when the thermoplastic elastomer composition does not contain the copolymer (C), whereas when the thermoplastic elastomer composition contains the copolymer (C), the size of the chars increases and the heat transfer inhibitory effect is improved. In a cone calorimeter test, when a 3 mm-thick flat plate obtained by molding the thermoplastic elastomer composition (I) or (II) containing the olefin-based thermoplastic elastomer composition (A1) or the styrene-based thermoplastic elastomer composition (A2) and the phosphorus-based flame retardant (B) is burned by radiant heat, when the thermoplastic elastomer composition does not contain the copolymer (C), many gaps for the char are generated and the molded body burns, but when the thermoplastic elastomer composition contains the copolymer (C), the gaps for the char are reduced, and char is formed by the burning of the sides, resulting in a dome shape. Although the mechanism is unclear, by adding copolymer (C), a stronger char is formed, suppressing heat transfer and making it possible to achieve flame retardancy of V-1 or higher in the UL94 test, and even V-0 flame retardancy. The copolymer (C) can exert the above effects even in a small amount.

[0100] [Molded body] A molded article according to one embodiment of the present invention is made of the above-mentioned thermoplastic elastomer composition (I) or the present thermoplastic elastomer composition (II). The shape of the molded product is not particularly limited, and may be in various shapes such as a plate, sheet, film, cable, or irregular shape.

[0101] The molded article can be obtained by molding the present thermoplastic elastomer composition (I) and / or (II). The molding method is not particularly limited, and examples thereof include extrusion processing, calendar processing, injection molding, roll, compression molding, press molding, blow molding, modeling by a 3D printer, and the like. As the 3D printer used here, it is preferable to use a printer of the material extrusion method (MEX method). The present thermoplastic elastomer composition (I) and / or (II) can be supplied to the 3D printer in the form of pellets, powder, granules, filaments, and the like. In particular, it is preferable to use a 3D printer of a type that can use a modeling material in the form of pellets or granules for molding. Examples of such printers include those that control the drive of the extrusion nozzle using a gantry method, those that control the drive of the extrusion nozzle using a robot arm method, and the like. The temperature at which the present thermoplastic elastomer compositions (I) and / or (II) are molded is, for example, 170 to 260°C.

[0102] The molded article in this embodiment has a durometer hardness (hereinafter also referred to as "Duro A hardness") measured according to JIS K 6253-3:2023 using a type A durometer, of preferably 39 or more, more preferably 66 or more, even more preferably 68 or more, and even more preferably 70 or more. As described above, the thermoplastic elastomer composition (I) and / or the thermoplastic elastomer composition (II) contains a specific thermoplastic elastomer composition (A1) or (A2), a phosphorus-based flame retardant (B), and a copolymer (C) of an α-olefin and an unsaturated carboxylic acid. Although the reason is unclear, the durometer hardness tends to be improved, especially when the copolymer (C) of an α-olefin and an unsaturated carboxylic acid is contained. As described above, the presence of the copolymer (C) between each thermoplastic elastomer composition (A1) or (A2) and the phosphorus-based flame retardant (B) is believed to improve the dispersibility of the phosphorus-based flame retardant (B) in each thermoplastic elastomer composition (A1) or (A2), and the present inventors have found that, as a result, the durometer hardness is also improved, which is a surprising result. The durometer A hardness can be set within the above range, and the thermoplastic elastomer composition (I) or (II) has a moderate hardness while maintaining the high flexibility, so that the obtained molded article is less likely to deform and can maintain a specific shape and dimensions.

[0103] The molded article in this embodiment has excellent flame retardancy. For example, the molded article containing the thermoplastic elastomer composition (I) containing the olefin-based thermoplastic elastomer composition (A1) can achieve V-1 or even V-0 as flame retardancy in the UL94 standard at a thickness of 1.6 mm. The molded article containing the thermoplastic elastomer composition (II) containing the styrene-based thermoplastic elastomer composition (A2) can achieve V-2 or HB as flame retardancy in the UL94 standard at a thickness of 1.6 mm.

[0104] The molded article in this embodiment can be used as a material in a wide range of fields, such as automobile parts (weather strips, ceiling materials, interior sheets, bumper moldings, side moldings, air spoilers, air duct hoses, various sealing materials and packings, etc.), civil engineering and building material parts (waterstop materials, joint materials, window frames, etc.), sporting goods (grips for golf clubs and tennis rackets), industrial parts (hose tubes, gaskets, etc.), home appliance parts (hoses, packings), medical equipment parts, electric wires, and miscellaneous goods. In particular, since it exhibits excellent flame retardancy, has high smoothness, excellent mechanical properties, and high flexibility (rubber elasticity), it can be suitably used as a sealing material or packing used in battery housings.

[0105] For example, a stampable sheet containing a thermoplastic resin, a flame retardant, and inorganic fibers and the thermoplastic elastomer composition (I) or (II) (molded article) can be integrally molded to obtain a molded article such as a battery pack cover. As a method of integral molding, for example, the thermoplastic elastomer composition (I) or (II) can be molded directly on the stampable sheet or the like by molding with the above-mentioned 3D printer. In this case, the thermoplastic elastomer composition (I) or (II) is considered to be bonded to the stampable sheet or the like by thermal fusion. At this time, the stampable sheet or the like may be heated before or during molding with the 3D printer in order to improve the thermal fusion property. The heating temperature is, for example, 40°C to 160°C. The molded article in this embodiment is molded from the thermoplastic elastomer composition (I) or (II). Therefore, unlike a thermosetting molded article, the molded article after use can be dissolved and reformed by reheating it, and can be recycled as a new product. EXAMPLES

[0106] The present invention will be specifically described below with reference to examples. However, the present invention is not limited to the following examples. In the following examples, % is based on mass unless otherwise specified. The following items were evaluated.

[0107] <Olefin-based thermoplastic elastomer composition (A1)> In Example 1, Comparative Example 1, and Comparative Example 2, Trexplane (registered trademark) 3555B manufactured by Mitsubishi Chemical Corporation (a composition containing an olefin copolymer rubber partially crosslinked with polypropylene and a hydrocarbon-based softener for rubber (paraffin-based oil), Duro A hardness: 52) was used as the olefin-based thermoplastic elastomer composition (A1). In Example 2 and Comparative Example 3, Trexplane (registered trademark) QT60MB (a composition containing polypropylene, an olefin copolymer rubber, and a hydrocarbon-based softener for rubber (paraffin-based oil), Duro A hardness: 57) manufactured by Mitsubishi Chemical Corporation was used as the olefin-based thermoplastic elastomer composition (A1).

[0108] <Styrene-based thermoplastic elastomer composition (A2)> In Example 3, as the styrene-based thermoplastic elastomer composition (A2), Mitsubishi Chemical Corporation's TEFABLOC (registered trademark) SJ5300C (a composition containing polypropylene, styrene-based rubber, and a hydrocarbon-based softener for rubber (paraffin-based oil), Duro A hardness: 44) was used. In Example 4 and Comparative Example 4, TEFABLOC (registered trademark) T320C (a composition containing polypropylene, styrene-based rubber, and a hydrocarbon-based softener for rubber (paraffin-based oil), Duro A hardness: 13) manufactured by Mitsubishi Chemical Corporation was used as the styrene-based thermoplastic elastomer composition (A2).

[0109] <Phosphorus-based flame retardants (B)> As the phosphorus-based flame retardant, a phosphorus-based flame retardant composition manufactured by ADEKA CORPORATION, Adeka STAB FP-2500S, was used, which is an intumescent flame retardant containing 50-60% piperazine pyrophosphate, 35-45% melamine pyrophosphate, and 3-6% zinc oxide relative to the total mass of the phosphorus-based flame retardant composition. <Copolymer of α-olefin and unsaturated carboxylic acid (C)> As the copolymer of α-olefin and unsaturated carboxylic acid, α-olefin-maleic anhydride copolymer (Mitsubishi Chemical Corporation, Diacalna 30M, weight average molecular weight 7,800) was used.

[0110] [Examples 1 to 4, Comparative Examples 1 to 4] The raw materials shown in Table 1 were blended in the ratios shown in Table 1 and mixed by hand blending. After that, using a φ30 mm co-rotating twin screw extruder (model name "BT-30", manufactured by Plastics Engineering Research Institute Co., Ltd., L / D=30), the mixture was melt-kneaded under conditions of a screw rotation speed of 250 rpm and a cylinder temperature of 200°C, and then dried at 70°C for 12 hours to obtain pellets. "L / D" indicates the ratio of the screw length (L) to the diameter (D). The pellets were used to prepare the following molded products, which were then subjected to the evaluations described below.

[0111] Each of the obtained pellets was press-molded using a 40t high-performance high-temperature vacuum press (model name "VH1-1747", manufactured by Kitagawa Seiki Co., Ltd.) under conditions of a molding temperature of 200°C and a molding pressure of 3.0 MPa to obtain a molded body (length 200 mm x width 150 mm x thickness 1.6 mm). A rectangular piece measuring 125 mm in length and 13 mm in width was cut from the molded article to prepare a test piece for UL94 evaluation. The molded article was punched out to obtain a JIS K6251 dumbbell-shaped No. 3 test piece, which was used to evaluate the tensile properties.

[0112] Each of the obtained pellets was press molded using a 40t high-performance high-temperature vacuum press (model name "VH1-1747", Kitagawa Seiki Co., Ltd.) under conditions of a molding temperature of 200°C and a molding pressure of 3.0 MPa to obtain a molded body (length 50 mm x width 50 mm x thickness 6 mm). The surface roughness (Sa) of the obtained test pieces was measured, and the durometer was used to measure the duro A hardness.

[0113] (1) Flame retardant (UL94) The evaluation test pieces (1.6 mm thick test pieces) obtained in each of the Examples and Comparative Examples were used to evaluate the flame retardancy in accordance with the UL 94 standard. The results are shown in Table 1.

[0114] (2) Tensile strength and tensile elongation The tensile strength and tensile elongation of the test pieces for evaluation obtained in the following examples and comparative examples were measured by a method according to JIS K6251:2017. The measurement conditions were a tensile speed of 500 mm / min and an atmospheric temperature of 23°C. The measurement device used was a tensile tester (product name: Autograph AG-X, manufactured by Shimadzu Corporation). The test piece used was the above-mentioned test piece for evaluation (dumbbell-shaped No. 3 test piece). Both ends of the test piece in the longitudinal direction were chucked with a chuck distance of 60 mm, and pulled at a crosshead speed of 500 mm / min, and the tensile strength and tensile elongation were measured three times, and the average values ​​were calculated. The results are shown in Table 1.

[0115] (3) Duro A hardness The test pieces for evaluation (length 50 mm × width 50 mm × thickness 6 mm) obtained in each of the Examples and Comparative Examples were measured for Duro A hardness in accordance with JIS K 6253-3: 2023 to evaluate flexibility. The results are shown in Table 1. The Duro A hardness of each of the olefin-based thermoplastic elastomer composition (A1) and the styrene-based thermoplastic elastomer composition (A2) used in each example and comparative example was measured as follows. Using an electric injection molding machine (manufactured by Nissei Plastic Industrial Co., Ltd.), the composition was filled into a sheet-shaped mold having a length of 120 mm, a width of 80 mm, and a thickness of 2 mm for an injection time of 3 seconds at a cylinder temperature of 220°C, a mold clamping force of 110 tf (1078 kN), and a mold temperature of 40°C. After the filling was completed, the molded injection product was cooled for 30 seconds and then removed. The Duro A hardness of the obtained injection molded product after 15 seconds was measured with reference to ISO 7619.

[0116] (4) Surface roughness (Sa) The surfaces of the evaluation specimens obtained in the Examples and Comparative Examples were measured using a surface roughness measuring device (AMETEK Co., Ltd., "NewView" (registered trademark)), and the average surface roughness Sa value was calculated from the obtained surface profile curve. When measuring Sa, the maximum and minimum values ​​were excluded from the 36 measurements, and the average of the measurements for 30 points was taken as the Sa value. The results are shown in Table 1.

[0117] [Table 1]

[0118] As is clear from the above examples, the thermoplastic elastomer composition (I) containing the olefin-based thermoplastic elastomer composition (A1) realizes excellent flame retardancy, achieves high Duro A hardness while maintaining excellent mechanical strength (tensile strength), and is also excellent in smoothness. The thermoplastic elastomer composition (II) containing the styrene-based thermoplastic elastomer composition (A2) has high smoothness and excellent mechanical strength (tensile strength) while maintaining appropriate Duro A hardness and flame retardancy. Comparative Examples 2 and 3, which do not contain the phosphorus-based flame retardant (B), are inferior in flame retardancy, and Comparative Example 1, which contains the phosphorus-based flame retardant (B) but does not contain the copolymer (C), is inferior in flexibility and smoothness. Comparing Example 1, Comparative Example 1 (without copolymer (C)) and Comparative Example 2 (without flame retardant (B) and copolymer (C)), Comparative Example 2 and Comparative Example 1 show that the addition of flame retardant (B) improves flame retardancy as well as Duro A hardness, but the smoothness and mechanical properties (tensile strength and tensile elongation) are reduced. On the other hand, in Example 1, which also contains copolymer (C), it was confirmed that the flame retardancy and Duro hardness values ​​were maintained while the smoothness and mechanical properties (tensile strength and tensile elongation) were improved to values ​​close to the original physical properties of the olefin-based thermoplastic elastomer composition (A1). Comparing Example 4 and Comparative Example 4, it was confirmed that Example 4 containing copolymer (C) significantly improved flame retardancy and mechanical properties, especially tensile elongation, while maintaining the duro hardness value and moderate smoothness of Comparative Example 4 containing only flame retardant (B).

Claims

1. A thermoplastic elastomer composition comprising an olefin-based thermoplastic elastomer composition (A1), a phosphorus-based flame retardant (B), and a copolymer of an α-olefin and an unsaturated carboxylic acid (C).

2. A thermoplastic elastomer composition comprising a styrene-based thermoplastic elastomer composition (A2), a phosphorus-based flame retardant (B), and a copolymer of an α-olefin and an unsaturated carboxylic acid (C).

3. The thermoplastic elastomer composition according to claim 1, wherein the olefin-based thermoplastic elastomer composition (A1) contains a crystalline polyolefin and an olefin-based copolymer rubber.

4. The thermoplastic elastomer composition according to claim 2 , wherein the styrene-based thermoplastic elastomer composition (A2) contains a styrene-based rubber.

5. The thermoplastic elastomer composition according to claim 1 or 2, wherein the phosphorus-based flame retardant (B) comprises a compound having a melamine structure or a piperazine structure.

6. The thermoplastic elastomer composition according to claim 1 or 2, wherein the phosphorus-based flame retardant (B) comprises an intumescent flame retardant.

7. 3. The thermoplastic elastomer composition according to claim 1, wherein the unsaturated carboxylic acid in the copolymer (C) of an α-olefin and an unsaturated carboxylic acid contains maleic anhydride.

8. The thermoplastic elastomer composition according to claim 1 or 2, wherein the proportion of the phosphorus-based flame retardant (B) to the total mass of the thermoplastic elastomer composition is 35 mass% or more.

9. 3. The thermoplastic elastomer composition according to claim 1, wherein the ratio of the copolymer (C) of an α-olefin and an unsaturated carboxylic acid to the phosphorus-based flame retardant (B) is 10 mass% or less.

10. 2. The thermoplastic elastomer composition according to claim 1, wherein a ratio of a total mass of the olefin-based thermoplastic elastomer composition (A1), the phosphorus-based flame retardant (B) and the copolymer (C) to a total mass of the thermoplastic elastomer composition is 60 mass% or more.

11. 3. The thermoplastic elastomer composition according to claim 2, wherein a ratio of a total mass of the styrene-based thermoplastic elastomer composition (A2), the phosphorus-based flame retardant (B), and the copolymer (C) to a total mass of the thermoplastic elastomer composition is 60 mass% or more.

12. A pellet comprising the thermoplastic elastomer composition according to claim 1 or 2.

13. A molded article comprising the thermoplastic elastomer composition according to claim 1 or 2.

14. The molded article according to claim 13, having a durometer hardness of 39 or more by a type A durometer measured in accordance with JIS K 6253-3:2023.

15. The molded article according to claim 13, having a flame retardancy of V-0 according to the UL94 standard at a thickness of 1.6 mm.

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