Flame-retardant resin composition and molded articles, electric wires, and cables using the same.

Abstract

To provide a polyethylene-based flame retardant resin composition that includes an inorganic flame retardant and a silicon acrylic graft copolymer resin which, when added in small quantities, offers improved flame resistance and sliding characteristics, as well as a molded product, a wire and a cable, each including the same.SOLUTION: A flame retardant resin composition contains the following components (I), (II), and (III). (I) a polyethylene resin: 100 pts.mass, (II) an inorganic flame retardant: 50-300 pts.mass, and (III) a silicone acryl graft copolymer resin: 1-20 pts.mass, which is a copolymer of a polyorganosiloxane represented by the formula (1), and at least one monomer selected from acrylate monomers and methacrylate monomers.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to flame-retardant resin compositions, more specifically, to polyethylene-based flame-retardant resin compositions containing an inorganic flame retardant and a silicone acrylic graft copolymer resin, molded articles using the same, and electric wires and cables. [Background technology]

[0002] Polyvinyl chloride resin compositions have traditionally been used as flame-retardant materials for electrical wire insulation and other applications. However, polyvinyl chloride resin compositions have the drawback of producing toxic halogen-containing gases when burned during fires or incineration. Therefore, development is underway to make olefin-based resins flame-retardant for use in electrical wires and other applications.

[0003] Resin compositions (non-halogen flame retardant materials) have been proposed that are polyolefin resins blended with metal hydrates such as aluminum hydroxide or magnesium hydroxide. For example, International Publication No. 2013 / 107971 discloses a non-halogen flame retardant polyethylene resin, which contains maleic anhydride-grafted polyethylene and a coupling agent containing an ethylene-acrylic acid ester-maleic anhydride ternary copolymer, with the aim of maintaining mechanical properties even in high temperature and high humidity environments. Furthermore, Japanese Patent Application Publication No. 2015-118817 and International Publication No. 2018 / 74233 use non-halogen resins with aliphatic amides or stearic acid as lubricants.

[0004] On the other hand, the flame retardancy grade required for flame-retardant materials for electric wires or cables is higher in Europe, the United States, and other regions than in Japan, due to differences in building structures, etc. In non-halogen flame-retardant polyethylene resins, it is generally necessary to increase the content of fillers such as metal hydrates in order to improve flame retardancy. Japanese Patent Publication No. 2012-102307 discloses a flame-retardant resin composition obtained by surface-treating particles of metal hydroxides such as magnesium hydroxide with a fatty acid-based material and adding this to a polyolefin-based resin, with the aim of obtaining excellent water resistance even with a high concentration of metal hydroxides.

[0005] However, in non-halogen flame-retardant polyethylene resins, increasing the content of inorganic flame retardants to improve flame retardancy leads to insufficient fluidity during extrusion molding, making it difficult to ensure moldability, and also makes it difficult to ensure mechanical properties such as tensile strength at break. Conventional flame-retardant resin compositions using magnesium hydroxide as a flame retardant are not necessarily sufficient materials that have excellent resistance to carbon dioxide whitening, as well as ensuring fluidity during molding and mechanical properties such as tensile strength at break.

[0006] Japanese Patent Publication No. 2021-147555 discloses a polyolefin-based flame-retardant resin composition containing a combination of a fatty acid-treated metal hydrate and a phosphate-ester-treated metal hydrate, which includes at least one of fatty acid-treated magnesium hydroxide and phosphate-ester-treated magnesium hydroxide. However, there is a need for the development of a flame-retardant resin composition that can improve flame retardancy more easily. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] International Publication No. 2013 / 107971 [Patent Document 2] Japanese Patent Publication No. 2015-118817 [Patent Document 3] International Publication No. 2018 / 74233

Patent Document 4

Patent Document 5

Summary of the Invention

Problems to be Solved by the Invention

[0008] The present invention has been made in view of the above circumstances, and aims to provide a polyethylene-based flame-retardant resin composition containing a silicone-acrylic graft copolymer resin capable of improving flame retardancy and slipperiness with a small amount of addition, a molded body using the same, and an electric wire and a cable.

Means for Solving the Problems

[0009] As a result of intensive studies to achieve the above object, the present inventor has found that a polyethylene-based flame-retardant resin composition containing an inorganic flame retardant and a silicone-acrylic graft copolymer resin solves the above problems, and has thus completed the present invention.

[0010] Therefore, the present invention provides the following flame-retardant resin composition, a molded body using the same, and an electric wire and a cable. A flame-retardant resin composition containing the following components (I), (II), and (III) (I) Polyethylene-based resin: 100 parts by mass, (II) Inorganic flame retardant: 50 to 300 parts by mass, and (III) A copolymer of a polyorganosiloxane represented by the following formula (1) and at least one monomer selected from an acrylate monomer and a methacrylate monomer, wherein the mass ratio of the polyorganosiloxane to the acrylate unit and the methacrylate unit is 50:50 to 90:10, and the silicone-acrylic graft copolymer resin: 1 to 20 parts by mass <​​​​​​​​​These are independently substituted or unsubstituted monovalent hydrocarbon groups having 1 to 20 carbon atoms, and R 2 (1) is a C1-C6 alkyl group having a mercapto group, an acryloxy group, or a methacryloxy group, or a vinyl group, and X is independently a substituted or unsubstituted C1-C20 monovalent hydrocarbon group, a C1-C20 alkoxy group, or a hydroxyl group, where a is a positive number from 1 to 10,000, b is a positive number from 0.1 to 1,000, and c is 2, provided that the bonding order of each siloxane unit in formula (1) above is not limited to the above. [Effects of the Invention]

[0011] The flame-retardant resin composition of the present invention, by blending a silicone acrylic graft copolymer resin with a polyethylene resin, exhibits improved flame retardancy and tactile properties compared to compositions containing only an inorganic flame retardant. [Modes for carrying out the invention]

[0012] The present invention relates to a flame-retardant resin composition containing (I) a polyethylene resin, (II) an inorganic flame retardant, and (III) the silicone acrylic graft copolymer resin described above. The following provides a detailed description of each component.

[0013] (I) Polyethylene resin can be composed of one or more types selected from ethylene homopolymers and copolymers mainly composed of ethylene. Examples of ethylene homopolymers include low-density polyethylene, linear low-density polyethylene, linear low-density polyethylene, and high-density polyethylene, but from the viewpoint of lightweight and excellent moldability, a density of 0.910 to 0.965 g / cm³ is selected. 3Preferably, the ethylene homopolymer has a melt mass flow rate of 0.01 to 200 g / 10 min at 190°C and a load of 2.16 kg. If the melt mass flow rate at 190°C and a load of 2.16 kg is within the above range, there is no risk of defects in the fluidity of the resin composition or the surface appearance of the molded article. More preferably, the melt mass flow rate at 190°C and a load of 2.16 kg is 0.01 to 60 g / 10 min. The melt mass flow rate is measured using an extrusion type plastometer or the like in accordance with the method specified in JIS K7210-1:2014. Furthermore, the durometer hardness (D) of the polyethylene resin is preferably 15 to 90, more preferably 20 to 85, and even more preferably 20 to 70.

[0014] Commercially available polyethylene resins can be used, including Novatec L LUE320, Novatec LDZE4K, and Novatec LDZF33 from Nippon Polyethylene; UBE, polyethylene L719, L518, L618, and C410 from Ube Maruzen Polyethylene; and Sumikasen C215, G201, G109, F236-0, and F411-0 from Sumitomo Chemical.

[0015] Examples of copolymers mainly composed of ethylene include random copolymers of ethylene with one or more α-olefins other than ethylene, block copolymers of ethylene with one or more α-olefins other than ethylene, ethylene-vinyl acetate copolymers, ethylene-(meth)acrylic acid ester copolymers, and ethylene-(meth)acrylic acid copolymers. Among copolymers mainly composed of ethylene, ethylene copolymers having a melt mass flow rate of 0.01 to 200 g / 10 min at 190°C and a load of 2.16 kg are preferred from the viewpoint of being lightweight and having excellent moldability. If the melt mass flow rate at 190°C and a load of 2.16 kg is within the above range, there is no risk of defects in the fluidity of the resin composition and the surface appearance of the molded article, and it is more preferable that it is 0.01 to 60 g / 10 min. Examples of α-olefins other than ethylene include propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, and 1-eicosene.

[0016] In the case of ethylene-vinyl acetate copolymers, ethylene-(meth)acrylic acid copolymers, and ethylene-(meth)acrylic acid ester copolymers, it is preferable that the melt mass flow rate, measured at a temperature of 190°C and a load of 2.16 kg in accordance with JIS K7210 (1999), be 50 g / 10 min or less, more preferably 0.05 to 30 g / 10 min, and even more preferably 0.1 to 10 g / 10 min. If the melt mass flow rate is too high, the mechanical properties will deteriorate, and if it is too low, the moldability will worsen.

[0017] Examples of (meth)acrylic acid esters in ethylene-(meth)acrylic acid copolymers include esters of (meth)acrylic acid with an alcohol having 1 to 8 carbon atoms. For example, methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, t-butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate are examples.

[0018] Ethylene-vinyl acetate copolymers, ethylene-(meth)acrylic acid copolymers, and ethylene-(meth)acrylic acid ester copolymers contain COOR-type functional groups. These copolymers have the following characteristics. (1) During thermal decomposition, a decarbonation reaction occurs, and it is converted directly into CO2. In other words, it generates a non-combustible gas without releasing combustion energy. (2) Because it is hydrophilic, it has high interfacial strength with the metal hydrate of the inorganic flame retardant, and even if a large amount of inorganic flame retardant is added, the degree of deterioration in physical properties is small. (3) Since the comonomer copolymerized with ethylene is bulky, it has high tolerance for inorganic flame retardants, and even when a large amount of inorganic flame retardant is added, the degree of deterioration in physical properties is small. The copolymer described above is advantageous as a base material for non-halogenated flame-retardant resin compositions due to the characteristics described above. Furthermore, the present invention is characterized by producing the crosslinked resin composition by melt kneading at low temperatures, which suppresses the drawback of reduced manufacturability due to the development of adhesive properties during composition production that can be achieved by using these resins.

[0019] (II) Examples of inorganic flame retardants include metal hydroxides, metal oxides, metal carbonate compounds, metal powders, boron compounds, and inorganic powders for flame retardants such as low-melting-point glass. Volume basis D of inorganic flame retardants 50 The value used as the average particle diameter (μm) is preferably between 0.5 and 5 μm. Particle diameter was measured using laser diffraction.

[0020] Examples of metal hydroxides include aluminum hydroxide, magnesium hydroxide, dolomite, hydrotalcite, calcium hydroxide, barium hydroxide, and zirconium hydroxide. Aluminum hydroxide and magnesium hydroxide are preferred. The metal hydroxide may also be surface-treated with a higher fatty acid such as stearic acid or a silane coupling agent. Using such a surface-treated metal hydroxide can improve dispersibility when kneading with the base polymer. The metal hydroxide may be a commercially available product. Magnesium hydroxide surface-treated with a silane coupling agent is preferred, and examples of commercially available products include Kisma 5L, Kisma 5N, Kisma 5P (all trade names, manufactured by Kyowa Chemical Co., Ltd.), and Magseas S series (trade name, manufactured by Kamishima Chemical Co., Ltd.). Examples of untreated magnesium hydroxide include Kisma 5 (trade name, manufactured by Kyowa Chemical Co., Ltd.) and Magnifin H5 (trade name, manufactured by Albemarle Co., Ltd.).

[0021] Examples of metal oxides include zinc molybdate, molybdenum trioxide, zinc stannate, tin oxide, aluminum oxide, iron oxide, titanium oxide, manganese oxide, zirconium oxide, zinc oxide, molybdenum oxide, cobalt oxide, bismuth oxide, chromium oxide, nickel oxide, copper oxide, and tungsten oxide.

[0022] Examples of metal carbonate compounds include zinc carbonate, magnesium carbonate, calcium carbonate, barium carbonate, basic magnesium carbonate, aluminum carbonate, iron carbonate, cobalt carbonate, and titanium carbonate.

[0023] Examples of metal powders include aluminum, iron, titanium, manganese, zinc, molybdenum, cobalt, bismuth, chromium, nickel, copper, tungsten, and tin.

[0024] Examples of boron compounds include zinc borate, zinc metaborate, barium metaborate, boric acid, and borax.

[0025] Examples of the low-melting-point glasses mentioned above include glassy compounds such as Sheeplee (Voxui-Brown), hydrated glass SiO2-MgO-H2O, PbO-B2O3 system, ZnO-P2O5-MgO system, P2O5-B2O3-PbO-MgO system, P-Sn-OF system, PbO-V2O5-TeO2 system, Al2O3-H2O system, and lead borosilicate system.

[0026] The amount of the inorganic flame retardant (II) is 50 to 300 parts by mass per 100 parts by mass of the polyethylene resin (I), preferably 80 to 250 parts by mass, and more preferably 100 to 200 parts by mass. If the amount of the inorganic flame retardant is below the lower limit, good results cannot be obtained in oxygen index and flame retardancy tests, and if it exceeds the upper limit, moldability will be poor.

[0027] The (III) silicone acrylic graft copolymer resin of the present invention is preferably a copolymer of a polyorganosiloxane represented by the following formula (1) and an acrylic acid ester monomer or a methacrylic acid ester monomer. Preferably, it is obtained by emulsion graft polymerization and drying of a mixture of (i) a polyorganosiloxane represented by the following formula (1) and (ii) an (meth)acrylic acid ester monomer, or a mixture of these components (i) and (ii) and an optional functional group-containing monomer (iii) copolymerizable with component (ii).

[0028] (i) Polyorganosiloxanes are represented by the following formula (1). [ka] In the formula, R 1 These are independently substituted or unsubstituted monovalent hydrocarbon groups having 1 to 20 carbon atoms, and R 2is an alkyl group having 1 to 6 carbon atoms with a mercapto group, acryloxy group or methacryloxy group, or a vinyl group, X is independently of each other a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, or a hydroxyl group, a is a positive number from 1 to 10,000, b is a positive number from 0.1 to 1000, and c is 2. In the above formula (1), the bonding order of the siloxane units is not limited as above, and each siloxane unit may form a block unit or may be randomly bonded.

[0029] In the above formula, R 1 is, independently of each other, a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, preferably a linear, branched or cyclic alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms. For example, alkyl groups such as methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, dodecyl group, tetradecyl group, hexadecyl group, octadecyl group, etc., cycloalkyl groups such as cyclopentyl group, cyclohexyl group, cycloheptyl group, etc., alkenyl groups such as vinyl group, allyl group, etc., aryl groups such as phenyl group, tolyl group, naphthyl group, etc., alkenylaryl groups such as vinylphenyl group, aralkyl groups such as benzyl group, phenylethyl group, phenylpropyl group, etc., alkenylaralkyl groups such as vinylbenzyl group, vinylphenylpropyl group, etc., or those in which some or all of the hydrogen atoms of these groups are substituted with halogen atoms such as fluorine, bromine, chlorine, acryloxy group, methacryloxy group, carboxyl group, alkoxy group, alkenyloxy group, amino group, alkyl or alkoxy or (meth)acryloxy-substituted amino group, etc. are included. R 1 is preferably a methyl group.

[0030] R 2 is an alkyl group having 1 to 6 carbon atoms substituted with a mercapto group, acryloxy group or methacryloxy group, or a vinyl group. For example, mercaptopropyl group, acryloxypropyl group, methacryloxypropyl group, vinyl group, etc. are preferable.

[0031] X is independently a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, or a hydroxyl group, and as an unsubstituted or substituted monovalent hydrocarbon group having 1 to 20 carbon atoms, R 1 Examples similar to those exemplified above can be given. Examples of alkoxy groups having 1 to 20 carbon atoms include methoxy, ethoxy, propoxy, butoxy, hexyloxy, heptyloxy, octyloxy, decyloxy, and tetradecyloxy groups. X is preferably a hydroxyl, methyl, butyl, phenyl, or methoxy group.

[0032] In the above formula (1), if a is a number greater than 10,000, the strength of the resulting cured product will be insufficient. a is an integer between 1 and 10,000, preferably between 500 and 6,000. If b is a number less than 0.1, the flexibility of the cured product will be poor, and if b is a number greater than 1,000, the tear strength of the cured product will decrease. b is a positive number between 0.1 and 1,000, preferably between 0.1 and 100, more preferably between 0.5 and 10, and even more preferably between 1 and 5. c is 2.

[0033] Preferably, at least two, more preferably two to four, of the X atoms at both ends of formula (1) are hydroxyl groups or alkoxy groups. The alkoxy group is preferably an alkoxy group having 1 to 4 carbon atoms, and more preferably a methoxy group. More preferably, the compound has silicon-bonded hydroxyl groups at both ends.

[0034] The polyorganosiloxane described in (i) above is preferably used in emulsion form and may be a commercially available product or synthesized. If synthesized, a known emulsion polymerization method may be used. For example, a cyclic organosiloxane or α,ω-dihydroxysiloxane oligomer, α,ω-dialkoxysiloxane oligomer, alkoxysilane, etc., which may have a fluorine atom, a (meth)acryloxy group, a carboxyl group, a hydroxyl group, or an amino group, can be easily synthesized by emulsifying and dispersing a silane coupling agent represented by the general formula (2) below in water using a surfactant, and then adding a catalyst such as an acid as needed to carry out a polymerization reaction. R 3 (4-e-f) R 4 f Si(OR 5 ) e (2) In equation (2) above, R 3 R is a monovalent organic group having a polymerizable double bond, for example, a mercapto group, an acryloxy group, or a C1-C6 alkyl group substituted with a methacryloxy group, and R 4 R is an alkyl group having 1 to 4 carbon atoms. 5 is an alkyl group having 1 to 4 carbon atoms, e is 2 or 3, f is 0 or 1, and e+f is 2 or 3.

[0035] The above cyclic organosiloxanes include hexamethylcyclotrisiloxane (D3), octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), dodecamethylcyclohexasiloxane (D6), 1,1-diethylhexamethylcyclotetrasiloxane, phenylheptamethylcyclotetrasiloxane, 1,1-diphenylhexamethylcyclotetrasiloxane, 1,3,5,7-tetravinyltetramethylcyclotetrasiloxane, 1,3,5,7-tetramethylcyclotetrasiloxane, 1,3,5,7-tetracyclohexyltetramethylcyclotetrasiloxane, tris(3,3,3-trifluoropropyl)trimethylcyclotrisiloxane, and 1,3,5,7-tetra(3-methacryloxypropyl)tetramethyl Examples include clotetrasiloxane, 1,3,5,7-tetra(3-acryloxypropyl)tetramethylcyclotetrasiloxane, 1,3,5,7-tetra(3-carboxypropyl)tetramethylcyclotetrasiloxane, 1,3,5,7-tetra(3-vinyloxypropyl)tetramethylcyclotetrasiloxane, 1,3,5,7-tetra(p-vinylphenyl)tetramethylcyclotetrasiloxane, 1,3,5,7-tetra[3-(p-vinylphenyl)propyl]tetramethylcyclotetrasiloxane, 1,3,5,7-tetra(N-acryloyl-N-methyl-3-aminopropyl)tetramethylcyclotetrasiloxane, and 1,3,5,7-tetra(N,N-bis(lauroyl)-3-aminopropyl)tetramethylcyclotetrasiloxane. Preferably, octamethylcyclotetrasiloxane and decamethylcyclopentasiloxane are used.

[0036] Examples of silane coupling agents include vinylsilanes such as vinyltrimethoxysilane, vinyltriethoxysilane, vinyltripropoxysilane, vinyltriisopropoxysilane, vinylmethyldimethoxysilane, and vinylmethyldiethoxysilane; γ-(meth)acryloxypropyltrimethoxysilane, γ-(meth)acryloxypropyltriethoxysilane, γ-(meth)acryloxypropyltripropoxysilane, γ-(meth)acryloxypropyltriisopropoxysilane, and γ-(meth)acryloxy Examples include acrylic silanes such as cypropyltributoxysilane, γ-(meth)acryloxypropylmethyldimethoxysilane, γ-(meth)acryloxypropylmethyldiethoxysilane, γ-(meth)acryloxypropylmethyldipropoxysilane, γ-(meth)acryloxypropylmethyldiisopropoxysilane, and γ-(meth)acryloxypropylmethyldibutoxysilane; and mercaptosilanes such as γ-mercaptopropylmethyldimethoxysilane and γ-mercaptopropyltrimethoxysilane. Alternatively, oligomers obtained by condensation polymerization of these may be more preferable as they suppress alcohol generation. Here, (meth)acryloxy refers to either acryloxy or methacryloxy. The silane coupling agent is preferably 0.01 to 20 parts by mass, and more preferably 0.01 to 5 parts by mass, per 100 parts by mass of a cyclic organosiloxane, α,ω-dihydroxysiloxane oligomer, α,ω-dialkoxysiloxane oligomer, or alkoxysilane.

[0037] By copolymerizing the above-mentioned cyclic organosiloxanes with the silane coupling agent represented by the above general formula (2), (R 2 (R 1 )SiO 2 / 2 A polyorganosiloxane represented by the above formula (1) having units is obtained, and the effect of grafting monomers of component (ii) or (iii) is obtained.

[0038] In the above reaction, any known polymerization catalyst may be used as the catalyst for polymerization. Among these, strong acids are preferred, with hydrochloric acid, sulfuric acid, dodecylbenzenesulfonic acid, citric acid, lactic acid, and ascorbic acid being examples. Dodecylbenzenesulfonic acid, which has emulsifying ability, is preferred. The amount of acid catalyst is preferably 0.01 to 10 parts by mass, and more preferably 0.2 to 2 parts by mass, per 100 parts by mass of cyclic organosiloxane, α,ω-dihydroxysiloxane oligomer, α,ω-dialkoxysiloxane oligomer, or alkoxysilane.

[0039] Examples of surfactants used in polymerization include anionic surfactants such as sodium lauryl sulfate, sodium laureth sulfate, N-acyl amino acid salts, N-acyl taurate salts, aliphatic soaps, and alkyl phosphates. Among these, those that are easily soluble in water and do not have polyethylene oxide chains are preferred. More preferably, N-acyl amino acid salts, N-acyl taurate salts, aliphatic soaps, and alkyl phosphates are preferred. Particularly preferred are sodium lauroyl methyl taurate, sodium myristoyl methyl taurate, and sodium lauryl sulfate. The amount of anionic surfactant is preferably 0.1 to 20 parts by mass, and more preferably 0.5 to 10 parts by mass, per 100 parts by mass of cyclic organosiloxane, α,ω-dihydroxysiloxane oligomer, α,ω-dialkoxysiloxane oligomer, or alkoxysilane.

[0040] The polymerization temperature is preferably 50 to 75°C, and the polymerization time is preferably 10 hours or more, and more preferably 15 hours or more. Furthermore, it is particularly preferable to mature the polymerization at 5 to 30°C for 10 hours or more after polymerization. In addition, the pH of the obtained polymerization solution is preferably 6 to 8.

[0041] In the polymerization reaction described above, for example, copolymerization of octamethyltetrasiloxane as a cyclic organosiloxane and γ-methacryloxypropylmethyldimethoxysilane as a silane coupling agent is as follows. [ka]

[0042] In the present invention, (ii) the acrylic acid ester monomer or methacrylic acid ester monomer (hereinafter sometimes referred to as the acrylic component or (meth)acrylic acid ester monomer) is an acrylic acid ester monomer or methacrylic acid ester monomer that does not have functional groups such as hydroxyl groups, amide groups, or carboxyl groups. Preferably, the acrylic acid ester or methacrylic acid ester has an alkyl group having 1 to 10 carbon atoms, and more preferably, the monomer has a glass transition temperature (hereinafter sometimes referred to as Tg) of the polymer of the acrylic component of 40°C or higher, more preferably 60°C or higher. Examples of such monomers include methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, isopropyl methacrylate, butyl methacrylate, ethyl methacrylate, and cyclohexyl methacrylate. The upper limit of Tg is preferably 200°C or lower, and more preferably 150°C or lower. The glass transition temperature can be measured according to JIS K7121.

[0043] Functional group-containing monomers (iii) copolymerizable with component (ii) above include monomers having unsaturated bonds, such as carboxyl groups, amide groups, hydroxyl groups, vinyl groups, and allyl groups. Examples include methacrylic acid, acrylic acid, acrylamide, allyl methacrylate, vinyl methacrylate, 2-hydroxyethyl methacrylate, and 2-hydroxypropyl methacrylate. Copolymerization of these can improve compatibility.

[0044] The (II) silicone acrylic graft copolymer resin emulsion of the present invention is obtained by emulsion graft polymerization of a mixture of (i) polyorganosiloxane obtained as described above and (ii) (meth)acrylic acid ester monomer, preferably monomer (iii) containing a functional group copolymerizable with component (ii).

[0045] The mass ratio of the polyorganosiloxane of formula (1) to the (meth)acrylic acid ester monomer during graft polymerization (the mass ratio of the polyorganosiloxane of formula (1) to the (meth)acrylic unit) is 50:50 to 90:10, preferably 70:30 to 90:10. If the amount of silicone component is less than the lower limit of the above mass ratio, sufficient flame retardancy may not be obtained.

[0046] The mixing ratio of component (i) and component (ii) described above is preferably 1 to 100 parts by mass of component (ii) per 100 parts by mass of component (i), more preferably 10 to 100 parts by mass of component (ii), and even more preferably 40 to 100 parts by mass of component (ii). Furthermore, when using component (i) and component (ii) and component (iii), it is preferable to use 1 to 100 parts by mass of component (ii) and 0.01 to 20 parts by mass of component (iii) per 100 parts by mass of component (i), more preferably 10 to 100 parts by mass of component (ii) and 0.01 to 20 parts by mass of component (iii), and even more preferably 40 to 100 parts by mass of component (ii) and 0.01 to 5 parts by mass of component (iii). In this case, it is preferable that the total mass ratio of component (ii) and component (iii) to the mass of component (i) be 50:50 to 90:10.

[0047] A radical initiator may be used in the above reaction. Examples of radical initiators include persulfates such as potassium persulfate and ammonium persulfate, hydrogen persulfate solution, t-butyl hydroperoxide, and hydrogen peroxide. If necessary, a redox system can also be used in combination with reducing agents such as sodium acidic sulfite, rongalit, L-ascorbic acid, tartaric acid, sugars, and amines. The amount of radical initiator is preferably 0.1 to 5% by mass of the total amount of components (ii) and (iii), and more preferably 0.5 to 3% by mass.

[0048] While graft polymerization is sufficiently possible with the surfactants contained in the polyorganosiloxane emulsion described above, anionic surfactants such as sodium lauryl sulfate, sodium laureth sulfate, N-acyl amino acid salts, N-acyl taurine salts, aliphatic soaps, and alkyl phosphates can be added to improve stability. Nonionic emulsifiers such as polyoxyethylene lauryl ether and polyoxyethylene tridecyl ether can also be added. When adding surfactants, the amount used is preferably 0.1 to 5% by mass of the total amount of components (ii) and (iii).

[0049] Furthermore, chain transfer agents can be added to adjust the molecular weight and grafting rate of the graft polymer.

[0050] The graft polymerization temperature is preferably 25 to 55°C, and more preferably 25 to 40°C. The polymerization time is preferably 2 to 8 hours, and more preferably 3 to 6 hours.

[0051] The silicone acrylic graft copolymer resin obtained in the manner described above is a polymer in which components (ii) and (iii) are randomly grafted onto component (i).

[0052] The silicone acrylic graft copolymer resin of the present invention preferably has a solid content of 30 to 50% by mass of the emulsion. The viscosity of this emulsion (at 25°C) is preferably 10 to 5,000 mPa·s or less, and more preferably 50 to 1,000 mPa·s. Viscosity can be measured using a rotational viscometer. The average particle size of this emulsion is preferably 1 μm or less, and more preferably 0.1 μm (100 nm) to 0.3 μm (300 nm). The pH is preferably 6 to 8. The average particle size can be measured using a laser diffraction / scattering particle size distribution analyzer.

[0053] The resulting silicone acrylic graft copolymer resin is in emulsion form. Therefore, the dispersion is concentrated by methods such as heating, dehydration, filtration, centrifugation, and decantation. After concentration, it is washed with water as needed, and then moisture is removed by heating and drying at atmospheric or reduced pressure, spray drying by spraying the dispersion into an airflow, or heating and drying using a fluid heat transfer medium. The mixture is then dried and converted into a powder. A drying temperature of 60 to 105°C is preferred. If the resulting powder has slightly aggregated, it may be crushed using a pulverizer such as a jet mill, ball mill, or hammer mill as appropriate.

[0054] The obtained silicone acrylic graft copolymer resin may be washed to remove any remaining cyclic organosiloxanes and surfactants. The solvent used for washing is preferably an alcohol-based organic solvent or a hydrocarbon-based organic solvent, such as a lower alcohol with 1 to 4 carbon atoms or an aliphatic hydrocarbon with 5 to 20 carbon atoms. More specifically, methanol, ethanol, isopropyl alcohol, hexane, and isododecane are more preferred. The washing method is not particularly limited, but for example, 100 parts by mass of the powder may be placed in a beaker, five times or more of the above-mentioned solvent may be added, and after stirring for several hours, the mixture may be filtered by suction. Afterward, washing with the same solvent or washing with a water-soluble solvent such as an alcohol-based solvent is even more effective. Washing is usually carried out at room temperature (25°C), but heating may be used if necessary.

[0055] If washed, the powder is re-dried and turned into a powder. Alternatively, filtered powder can be simply dried in a dryer at a temperature of 40°C to 200°C for several hours, or a fluidized bed dryer may be used.

[0056] The silicone acrylic graft copolymer resin powdered in this manner preferably has an average particle size of 150 μm or less, preferably 10 to 120 μm, and more preferably 10 to 100 μm. The average particle size is measured using a laser diffraction / scattering particle size distribution analyzer as described above. Furthermore, the weight-average molecular weight of the silicone acrylic graft copolymer resin is preferably 50,000 to 500,000. If it is less than 50,000, precipitation on the surface of the rubber compound may become severe, and if it exceeds 500,000, the friction reduction effect may be insufficient. The weight-average molecular weight was calculated by mixing the emulsion with isopropyl alcohol (IPA), extracting and drying the oil (organopolysiloxane), dissolving 1 g of the mixture in 100 mL of toluene, measuring the kinematic viscosity at 25°C, and then converting this value to the molecular weight of dimethyl silicone. More specifically, it was calculated using a correlation diagram between the viscosity of dimethyl silicone oil and its weight-average molecular weight, based on viscosity values ​​measured with an Ubbelohde viscometer.

[0057] The glass transition temperature (hereinafter sometimes referred to as Tg) of the silicone acrylic graft copolymer resin is 40°C or higher, preferably 60°C or higher, with an upper limit of preferably 200°C or lower, and more preferably 150°C or lower. The glass transition temperature can be measured according to JIS K7121.

[0058] (II) The amount of silicone acrylic graft copolymer resin added is 1 to 20 parts by mass, preferably 1 to 15 parts by mass, per 100 parts by mass of polyethylene resin (I). Below the lower limit, no improvement in the flame retardancy of the molded article is observed, and above the upper limit, the flame retardancy of the molded article may be significantly reduced.

[0059] The flame-retardant resin composition of the present invention may contain various commonly used additives, such as antioxidants, metal deactivators, fillers, lubricants, colorants, ultraviolet absorbers, light stabilizers, and antistatic agents, as appropriate, within limits that do not impair the objectives of the present invention.

[0060] As antioxidants, amine-based antioxidants such as polymers of 4,4'-dioctyl diphenylamine, N,N'-diphenyl-p-phenylenediamine, and 2,2,4-trimethyl-1,2-dihydroquinoline, pentaerythrityl-tetrakis(3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate), octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, 1,3, Examples include phenolic antioxidants such as 5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene, sulfur-based antioxidants such as bis(2-methyl-4-(3-n-alkylthiopropionyloxy)-5-t-butylphenyl) sulfide, 2-mercaptobenzimidazole and its zinc salt, and pentaerythritol-tetrakis(3-lauryl-thiopropionate).

[0061] Examples of metal deactivators include N,N'-bis(3-(3,5-di-t-butyl-4-hydroxyphenyl)propionyl)hydrazine, 3-(N-salicyroyl)amino-1,2,4-triazole, and 2,2'-oxamide bis-(ethyl 3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate).

[0062] Examples of fillers include carbon, clay, and white carbon.

[0063] Lubricants include hydrocarbon-based, fatty acid-based, fatty acid amide-based, ester-based, alcohol-based, and metal soap-based lubricants. Among these, ester-based, alcohol-based, and metal soap-based lubricants such as Wax E and Wax OP (both trade names, manufactured by Hoechst) exhibit both internal and external lubricity. Of these, zinc stearate, magnesium stearate, and calcium stearate have the effect of improving insulation resistance, and zinc stearate and magnesium stearate also have the effect of preventing eye discharge. Furthermore, by using fatty acid amides as lubricants in combination, it becomes possible to easily control the adhesion with the conductor.

[0064] The flame-retardant resin composition of the present invention can be obtained by melt-kneading each of the above components using a commonly used kneading device such as a twin-screw extruder, Banbury mixer, kneader, or roll. The stirring speed during melt-kneading is preferably 20 to 60 rpm, and the molding temperature is preferably 120°C to 140°C. The molded article obtained from the flame-retardant resin composition of the present invention has an oxygen index greater than 34, preferably greater than 35, as measured by a method in accordance with JIS K 7201-2:2007. The oxygen index is the minimum oxygen concentration required for a material to sustain combustion, and the higher the value of the oxygen index, the better the flame retardancy. The molded article obtained from the flame-retardant resin composition of the present invention can have excellent flammability.

[0065] The resin molded articles of the present invention can be molded into various shapes such as electric wires / cables, hollow tubes, and sheets. In the case of electric wires, there are no particular restrictions on the conductor diameter or conductor material, and these can be appropriately determined according to the application. There are also no particular restrictions on the thickness of the resin composition coating layer formed around the conductor, but 0.15 to 1 mm is preferred. Furthermore, the insulating layer may have a multilayer structure, and may have an intermediate layer in addition to the coating layer formed with the insulating resin composition of the present invention. In the case of cables, several conductors, optical fibers, etc., coated with this resin composition may be bundled together, twisted, and then coated with this resin composition on the outside; several conductors, optical fibers, etc., coated with other resin compositions may be bundled together, twisted, and then coated with this resin composition on the outside; or several conductors, optical fibers, etc., coated with this resin composition may be bundled together, twisted, and then coated with other resin compositions on the outside. [Examples]

[0066] The present invention will be described in more detail below with reference to manufacturing examples, embodiments, and comparative examples, but the present invention is not limited to the embodiments described below. In the following examples, parts and % refer to parts by mass and mass%, respectively.

[0067] The measurement methods used in the following manufacturing example and comparative manufacturing example are as follows. <Measurement of solid content> Approximately 1 g of the resin emulsion (sample) from each example was accurately weighed into an aluminum foil dish, placed in a drying oven maintained at approximately 105°C, heated for 1 hour, then removed from the oven and allowed to cool in a desiccator. The weight of the dried sample was measured, and the evaporation residue was calculated using the following formula.

number

[0068] <Measurement of average particle size of emulsion> The particle size of each resin emulsion was measured using a laser diffraction / scattering particle size distribution analyzer (LA950V2) manufactured by Horiba, Ltd.

[0069] <Measurement of glass transition temperature Tg> The glass transition temperature (Tg) was measured using a flow tester manufactured by Shimadzu Corporation on approximately 1 g of powdered silicone acrylic copolymer resin obtained by spray drying. The Tg was determined by applying a load of 5 kgf and increasing the temperature by 5°C per minute.

[0070] <Method for measuring the particle size of powders> The method for measuring the average particle size in the above examples and comparative examples is as follows. A laser diffraction particle size analyzer (LA-950V2, Horiba, Ltd.) was used to measure the average particle size. In production examples 1 to 5, the resin refractive index was set to 1.45 and the methanol refractive index to 1.329. The powders obtained in production examples 1 to 5 were directly added to the methanol being stirred in the instrument, and the average particle size based on the volume of the resin was measured. <Method for measuring weight-average molecular weight> The weight-average molecular weight of organopolysiloxane was calculated using a correlation diagram between the kinematic viscosity and weight-average molecular weight of organopolysiloxane, obtained by dissolving 1 g of thoroughly dried organopolysiloxane in 100 mL of toluene and measuring the value with an Ubbelohde viscometer.

[0071] <Examples of silicone acrylic graft copolymer resin production and comparative production examples> [Manufacturing Example 1] Dissolve 600g of octamethyltetracyclosiloxane, 0.48g of γ-methacryloxypropylmethyldiethoxysilane (Shin-Etsu Chemical Co., Ltd. "KBM-502"), and 6g of sodium lauryl sulfate in 54g of deionized water, and dissolve 6g of dodecylbenzenesulfonic acid in 54g of pure water in a 2L polyethylene beaker. Emulsify uniformly using a homomixer, then gradually add 490g of water to dilute, and apply a pressure of 300kgf / cm². 2 The mixture was passed through a high-pressure homogenizer twice to obtain a homogenized white emulsion. This emulsion was transferred to a 2 L glass flask equipped with a stirrer, thermometer, and reflux condenser, and polymerization was carried out at 55°C for 10-20 hours. After maturation at 10-20°C for 10-20 hours, the pH was neutralized to near neutral with 12 g of 10% sodium carbonate aqueous solution. The resulting silicone emulsion had a non-volatile content of 45.0% after drying at 105°C for 3 hours, and the organopolysiloxane in the emulsion was a non-flowing, soft gel. The organopolysiloxane in the above emulsion has the structure of formula (1) below, [ka] R 1 R is a methyl group, 2The group is a γ-methacryloxypropyl group, where two of the X groups at each end are methyl groups, and the remaining X group is either a hydroxyl or methoxy group. The compositions of a, b, and c are shown in Table 1. The weight-average molecular weight is approximately 250,000. To the silicone emulsion obtained above, 226 g of methyl methacrylate (MMA) was added dropwise over 3 to 5 hours while a redox reaction was carried out at 30°C with a peroxide and a reducing agent to perform an acrylic graft copolymerization to the silicone resin component (organopolysiloxane component), yielding a silicone acrylic graft copolymer resin emulsion with a non-volatile content of 45.2%. The emulsion was spray-dried using a commercially available spray dryer (inlet temperature 150°C) to volatilize it to a volatile content of 1.0% to obtain a resin powder.

[0072] [Manufacturing Example 2] Dissolve 600g of octamethyltetracyclosiloxane, 0.48g of γ-methacryloxypropylmethyldiethoxysilane (Shin-Etsu Chemical Co., Ltd. "KBM-502"), 0.96g of hexamethyldisiloxane, and 6g of sodium lauryl sulfate in 54g of deionized water, and dissolve 6g of dodecylbenzenesulfonic acid in 54g of pure water in a 2L polyethylene beaker. Emulsify uniformly using a homomixer, then gradually add 490g of water to dilute, and apply a pressure of 300kgf / cm². 2 The mixture was passed through a high-pressure homogenizer twice to obtain a homogenized white emulsion. This emulsion was transferred to a 2L glass flask equipped with a stirrer, thermometer, and reflux condenser, and polymerization was carried out at 55°C for 10-20 hours. After maturation at 10-20°C for 10-20 hours, the pH was neutralized to near neutral with 12g of 10% sodium carbonate aqueous solution. After drying at 105°C for 3 hours, the non-volatile content (solids) of this emulsion was 45.0%, and the organopolysiloxane in the emulsion was a non-flowing, soft gel. The organopolysiloxane in the above emulsion has the structure of formula (1) above, R 1 R is a methyl group, 2 The group is a γ-methacryloxypropyl group, and at each terminal, X is a methyl group. The composition of a, b, and c is shown in Table 1. The weight-average molecular weight is approximately 120,000. The silicone emulsion obtained above was subjected to a redox reaction with peroxide and reducing agent at 30°C by dropwise adding 226g of methyl methacrylate (MMA) over 3-5 hours, thereby copolymerizing the silicone resin component (organopolysiloxane component) with acrylic grafts, and a silicone-acrylic graft copolymer resin emulsion with a non-volatile content of 45.0% was obtained. The emulsion was spray-dried (inlet temperature 150°C) to volatilize the volatile content to 1.0% to obtain a resin powder.

[0073] [Manufacturing Example 3] Dissolve 600g of octamethyltetracyclosiloxane, 0.48g of γ-methacryloxypropylmethyldiethoxysilane (Shin-Etsu Chemical Co., Ltd. "KBM-502"), and 6g of sodium lauryl sulfate in 54g of deionized water, and dissolve 6g of dodecylbenzenesulfonic acid in 54g of pure water in a 2L polyethylene beaker. Emulsify uniformly using a homomixer, then gradually add 490g of water to dilute, and apply a pressure of 300kgf / cm². 2 The mixture was passed through a high-pressure homogenizer twice to obtain a homogenized white emulsion. This emulsion was transferred to a 2L glass flask equipped with a stirrer, thermometer, and reflux condenser, and polymerization was carried out at 55°C for 10-20 hours. After maturation at 5-10°C for 10-20 hours, the pH was neutralized to near neutral with 12g of 10% sodium carbonate aqueous solution. After drying at 105°C for 3 hours, the non-volatile content (solids) of this emulsion was 45.0%, and the organopolysiloxane in the emulsion was a non-flowing, soft gel. The organopolysiloxane in the above emulsion has the structure of formula (1) above, R 1 R is a methyl group, 2 The group is a γ-methacryloxypropyl group, where two of the X groups at each terminal are methyl groups, and the remaining X group is either a hydroxyl or methoxy group. The compositions of a, b, and c are shown in Table 1. The weight-average molecular weight is approximately 400,000. The silicone emulsion obtained above was subjected to a redox reaction with peroxide and reducing agent at 30°C while adding 226g of methyl methacrylate (MMA) dropwise over 3-5 hours, thereby copolymerizing the silicone resin component (organopolysiloxane component) with acrylic grafts, and a silicone-acrylic graft copolymer resin emulsion with a non-volatile content of 45.3% was obtained. The emulsion was spray-dried (inlet temperature 150°C) to volatilize the volatile content to 1.0% to obtain a resin powder.

[0074] [Manufacturing Example 4] Dissolve 600g of octamethyltetracyclosiloxane, 0.48g of γ-methacryloxypropylmethyldiethoxysilane (Shin-Etsu Chemical Co., Ltd. "KBM-502"), and 6g of sodium lauryl sulfate in 54g of deionized water, and dissolve 6g of dodecylbenzenesulfonic acid in 54g of pure water in a 2L polyethylene beaker. Emulsify uniformly using a homomixer, then gradually add 490g of water to dilute, and apply a pressure of 300kgf / cm². 2 The mixture was passed through a high-pressure homogenizer twice to obtain a homogenized white emulsion. This emulsion was transferred to a 2L glass flask equipped with a stirrer, thermometer, and reflux condenser, and polymerization was carried out at 55°C for 10-20 hours. After maturation at 10-20°C for 10-20 hours, the pH was neutralized to near neutral with 12g of 10% sodium carbonate aqueous solution. After drying at 105°C for 3 hours, the non-volatile content (solids) of this emulsion was 45.0%, and the organopolysiloxane in the emulsion was a non-flowing, soft gel. The organopolysiloxane in the above emulsion has the structure of formula (1) above, R 1 R is a methyl group, 2 The group is a γ-methacryloxypropyl group, where at each terminal, two of the X groups are methyl groups, and the remaining X group is either a hydroxyl or methoxy group. The composition of a, b, and c is shown in Table 1. The weight-average molecular weight is approximately 250,000. The silicone emulsion obtained above was subjected to a redox reaction with peroxide and reducing agent at 30°C while adding 528g of methyl methacrylate (MMA) dropwise over 3-5 hours, thereby copolymerizing the silicone resin component (organopolysiloxane component) with acrylic grafts, and a silicone-acrylic graft copolymer resin emulsion with a non-volatile content of 45.5% was obtained. The emulsion was spray-dried (inlet temperature 150°C) to volatilize the volatile content to 1.0% to obtain a resin powder.

[0075] [Manufacturing Example 5] Dissolve 600g of octamethyltetracyclosiloxane, 0.48g of γ-methacryloxypropylmethyldiethoxysilane (Shin-Etsu Chemical Co., Ltd. "KBM-502"), and 6g of sodium lauryl sulfate in 54g of deionized water, and dissolve 6g of dodecylbenzenesulfonic acid in 54g of pure water in a 2L polyethylene beaker. Emulsify uniformly using a homomixer, then gradually add 490g of water to dilute, and apply a pressure of 300kgf / cm². 2 The mixture was passed through a high-pressure homogenizer twice to obtain a homogenized white emulsion. This emulsion was transferred to a 2L glass flask equipped with a stirrer, thermometer, and reflux condenser, and polymerization was carried out at 55°C for 10-20 hours. After maturation at 10-20°C for 10-20 hours, the pH was neutralized to near neutral with 12g of 10% sodium carbonate aqueous solution. After drying at 105°C for 3 hours, the non-volatile content (solids) of this emulsion was 45.0%, and the organopolysiloxane in the emulsion was a non-flowing, soft gel. The organopolysiloxane in the above emulsion has the structure of formula (1) above, R 1 R is a methyl group, 2 The group is a γ-methacryloxypropyl group, where at each terminal, two of the X groups are methyl groups, and the remaining X group is either a hydroxyl or methoxy group. The composition of a, b, and c is shown in Table 1. The weight-average molecular weight is approximately 250,000. The silicone emulsion obtained above was subjected to a redox reaction with peroxide and reducing agent at 30°C by dropwise adding 144g of methyl methacrylate (MMA) over 3-5 hours, thereby copolymerizing the silicone resin component (organopolysiloxane component) with acrylic grafts, and a silicone-acrylic graft copolymer resin emulsion with a non-volatile content of 44.3% was obtained. The emulsion was spray-dried (inlet temperature 150°C) to volatilize the volatile content to 1.0% to obtain a resin powder.

[0076] [Manufacturing Example 6] Dissolve 600g of octamethyltetracyclosiloxane, 0.48g of γ-methacryloxypropylmethyldiethoxysilane (Shin-Etsu Chemical Co., Ltd. "KBM-502"), and 6g of sodium lauryl sulfate in 54g of deionized water, and dissolve 6g of dodecylbenzenesulfonic acid in 54g of pure water in a 2L polyethylene beaker. Emulsify uniformly using a homomixer, then gradually add 490g of water to dilute, and apply a pressure of 300kgf / cm². 2 The mixture was passed through a high-pressure homogenizer twice to obtain a homogenized white emulsion. This emulsion was transferred to a 2L glass flask equipped with a stirrer, thermometer, and reflux condenser, and polymerization was carried out at 55°C for 10-20 hours. After maturation at 10-20°C for 10-20 hours, the pH was neutralized to near neutral with 12g of 10% sodium carbonate aqueous solution. After drying at 105°C for 3 hours, the non-volatile content (solids) of this emulsion was 45.0%, and the organopolysiloxane in the emulsion was a non-flowing, soft gel. The organopolysiloxane in the above emulsion has the structure of formula (1) above, R 1 R is a methyl group, 2 The group is a γ-methacryloxypropyl group, where at each terminal, two of the X groups are methyl groups, and the remaining X group is either a hydroxyl or methoxy group. The composition of a, b, and c is shown in Table 1. The weight-average molecular weight is approximately 250,000. To the silicone emulsion obtained above, 113g of methyl methacrylate (MMA) and 113g of butyl acrylate (BA) were added dropwise over 3-5 hours while a redox reaction was carried out at 30°C with peroxides and reducing agents to copolymerize the silicone resin component (organopolysiloxane component) with acrylic grafts, yielding a silicone-acrylic graft copolymer resin emulsion with a non-volatile content of 44.9%. This was then spray-dried (inlet temperature 150°C) to reduce the volatile content to 1.0% and obtain a resin powder.

[0077] [Comparative Manufacturing Example 1] Dissolve 600g of octamethylcyclotetrasiloxane, 0.6g of γ-methacryloxypropylmethyldiethoxysilane (Shin-Etsu Chemical Co., Ltd. "KBM-502"), and 6g of sodium lauryl sulfate in 54g of pure water, and dissolve 6g of dodecylbenzenesulfonic acid in 54g of pure water in a 2L polyethylene beaker. Emulsify uniformly using a homomixer, then gradually add 470g of water to dilute, and apply a pressure of 300kgf / cm². 2 The mixture was then passed through a high-pressure homogenizer twice to obtain a uniform white emulsion. This emulsion was transferred to a 2L glass flask equipped with a stirrer, thermometer, and reflux condenser, and polymerization was carried out at 55°C for 24 hours. After aging at 0°C for 24 hours, it was neutralized to near-neutral pH with 12g of 10% sodium carbonate aqueous solution to obtain a silicone emulsion. The organopolysiloxane in the above emulsion has the structure of formula (1) above, R 1 R is a methyl group, 2 The group is a γ-methacryloxypropyl group, where at each terminal, two of the X groups are methyl groups, and the remaining X group is either a hydroxyl or methoxy group. The composition of a, b, and c is shown in Table 1. The weight-average molecular weight is approximately 250,000. The silicone emulsion obtained above was subjected to a redox reaction with peroxide and reducing agent at 30°C while dropwise adding 792g of methyl methacrylate (MMA) over 3-5 hours to the silicone emulsion, thereby copolymerizing the silicone resin component with acrylic grafts and obtaining a silicone-acrylic graft copolymer resin emulsion with a non-volatile content of 45%. This emulsion was then spray-dried to reduce the volatile content to 1.2%, yielding a resin powder.

[0078] [Comparative Manufacturing Example 2] Dissolve 600g of octamethylcyclotetrasiloxane, 0.6g of γ-methacryloxypropylmethyldiethoxysilane (Shin-Etsu Chemical Co., Ltd. "KBM-502"), and 6g of sodium lauryl sulfate in 54g of pure water, and dissolve 6g of dodecylbenzenesulfonic acid in 54g of pure water in a 2L polyethylene beaker. Emulsify uniformly using a homomixer, then gradually add 470g of water to dilute, and apply a pressure of 300kgf / cm². 2 The mixture was then passed through a high-pressure homogenizer twice to obtain a uniform white emulsion. This emulsion was transferred to a 2L glass flask equipped with a stirrer, thermometer, and reflux condenser, and polymerization was carried out at 55°C for 24 hours. After aging at 0°C for 24 hours, it was neutralized to near-neutral pH with 12g of 10% sodium carbonate aqueous solution to obtain a silicone emulsion. The organopolysiloxane in the above emulsion has the structure of formula (1) above, R 1 R is a methyl group, 2 The group is a γ-methacryloxypropyl group, where two of the X groups at each end are methyl groups, and the remaining X group is either a hydroxyl or methoxy group. The compositions of a, b, and c are shown in Table 1. The weight-average molecular weight is approximately 250,000. The silicone emulsion obtained above was subjected to a redox reaction with peroxide and reducing agent at 30°C while dropwise adding 28g of methyl methacrylate (MMA) over 3-5 hours, thereby copolymerizing the acrylic graft onto the silicone resin component and obtaining a silicone-acrylic graft copolymer resin emulsion with a non-volatile content of 44.2%. This emulsion was then spray-dried to reduce the volatile content to 1.2%, yielding a resin powder.

[0079] Table 1 shows the composition and properties of the organopolysiloxane in the emulsion, the properties of the emulsion, and the properties of the obtained silicone acrylic graft copolymer resin in the above production example and comparative production example. [Table 1]

[0080] <Forming method> Examples 1-7, Comparative Manufacturing Examples 1-2 Ethylene-ethyl acrylate copolymer (EEA resin, product name: NUC-6520, manufactured by ENEOS NUC Corporation), magnesium hydroxide (product name: MagSeeds S, manufactured by Kamishima Chemical Industry Co., Ltd.), and the resin powder obtained in the examples or comparative examples were kneaded in a kneader at approximately 120°C and 50 rpm in the amounts shown in the table below, and molded into a plate approximately 4 mm thick by pressing. Test pieces were extracted by cutting. The oxygen index, appearance, static and dynamic friction coefficient, and tactile feel of the obtained molded products were evaluated. The results are shown in Tables 2 and 3. The density of the EEA resin used in the examples and comparative examples was 0.94 g / cm³. 3 The melt mass flow rate measured at 190°C and a load of 2.16 kg in accordance with JIS K7210-1:2014 is 1.6 g / 10 min, the ethyl acrylate content is 24% by mass, and the durometer hardness (D) is 85. The magnesium hydroxide used in the examples and comparative examples is magnesium hydroxide for flame retardants that has been surface-treated with a silane coupling agent and has an average particle size of 1.0 μm.

[0081] The measurement methods used in the examples and comparative examples are as follows. <Oxygen Index Test> The oxygen index of the molded body was measured for the above test specimens using a method compliant with JIS K 7201-2:2007. Sample shape: I-shape, 80 x 10 x 4 mm Test conditions: Method A Measurement equipment: Candle combustion test machine AC2 type was used. The flammability was evaluated based on the obtained oxygen index. A higher oxygen index value indicates better flame retardancy.

[0082] <Exterior> The appearance of the molded piece was observed visually. ○: It was a clean molded piece with no aggregates. ×: Aggregates were observed.

[0083] <Measurement of static friction coefficient> Using a HEIDON TYPE-38 (manufactured by Shinto Kagaku Co., Ltd.), a 200g metal indenter was brought into perpendicular contact with each of the above examples of coatings and moved at a speed of 3 cm / min. The frictional force was measured, and the static friction coefficient and kinetic friction coefficient were calculated from the frictional force.

[0084] <Tactile sensation> The tactile feel of a molded body was evaluated as "○" if the static friction coefficient obtained from the above static-dynamic friction coefficient measurement was less than 0.55, the dynamic friction coefficient was less than 0.50, and the difference between the static and dynamic friction coefficients was 0.05 or less. Molded bodies with a "○" tactile feel evaluation have better surface slipperiness compared to molded bodies with an "×" evaluation.

[0085] [Table 2]

[0086] [Table 3] [Industrial applicability]

[0087] As described above, molded articles made from the flame-retardant resin composition of the present invention exhibit excellent flame retardancy and tactile properties. Molded articles made from the flame-retardant resin composition of the present invention can be molded into various shapes such as hollow tubes and sheets, and are suitable for use as coatings for electric wires and cables.

Claims

1. The following components (I), (II), and (III) (I) Polyethylene resin: 100 parts by mass, (II) Inorganic flame retardant: 50 to 300 parts by mass, (III) A copolymer of a polyorganosiloxane represented by the following formula (1) and at least one monomer selected from acrylic acid ester monomers and methacrylic acid ester monomers, wherein the mass ratio of the polyorganosiloxane to the acrylic acid ester units and methacrylic acid ester units is 50:50 to 90:10, and the average particle size is 80 μm or more and 150 μm or less, a silicone acrylic graft copolymer resin: 1 to 20 parts by mass A molded article made of a flame-retardant resin composition, wherein the static friction coefficient of the surface of the molded article is less than 0.55, the dynamic friction coefficient is less than 0.50, and the difference between the static friction coefficient and the dynamic friction coefficient is 0.05 or less, the molded article 【Chemistry 1】 (In the formula, R １ These are independently substituted or unsubstituted monovalent hydrocarbon groups having 1 to 20 carbon atoms, and R ２ (1) is a C1-C6 alkyl group having a mercapto group, an acryloxy group, or a methacryloxy group, or a vinyl group; X is independently a substituted or unsubstituted C1-C20 monovalent hydrocarbon group, a C1-C20 alkoxy group, or a hydroxyl group; a is a positive number from 1 to 10,000; b is a positive number from 0.1 to 1,000; and c is 2, provided that the bonding order of each siloxane unit in formula (1) is not limited to the above.

2. In the above formula (1), R １ The molded article according to claim 1, wherein at least one of the X groups at both ends is independently a linear, branched, or cyclic alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms.

3. The molded article according to claim 1, wherein at least two of the X in formula (1) above are hydroxyl groups or alkoxy groups.

4. The molded article according to claim 1, wherein the silicone acrylic graft copolymer resin has an average particle size of 80 μm or more and 100 μm or less.

5. The aforementioned silicone acrylic graft copolymer resin is (i) A polyorganosiloxane represented by formula (1) above, (ii) Acrylate ester monomer or methacrylic ester monomer, A functional group-containing monomer (iii) that can copolymerize with any of the above (ii) components and A molded article according to claim 1, which is a copolymer of the above.

6. The molded article according to claim 1, wherein the polyethylene resin is at least one selected from ethylene polymer, random copolymer of ethylene and one or more α-olefins other than ethylene, block copolymer of ethylene and one or more α-olefins other than ethylene, ethylene-vinyl acetate copolymer, ethylene-(meth)acrylic acid ester copolymer, and ethylene-(meth)acrylic acid copolymer.

7. The molded article according to claim 1, wherein the inorganic flame retardant is selected from metal hydroxides, surface-treated metal hydroxides, metal oxides, metal carbonate compounds, metal powders, boron compounds, and low-melting-point glass.

8. The molded article according to claim 7, wherein the inorganic flame retardant is a metal hydroxide surface-treated with a higher fatty acid or a silane coupling agent.

9. A molded article according to any one of claims 1 to 8, which is tubular or sheet-shaped.

10. An electric wire having a layer made of a molded body according to any one of claims 1 to 8.

11. A cable having a layer made of a molded body according to any one of claims 1 to 8.

Images