Polyolefin resin composition and wiring material

Abstract

Provided are: a polyolefin resin composition that contains a base resin which includes 5-20 mass% a cyclic olefin resin and 3-20 mass% an ultra-high molecular weight polyethylene resin composition; and a wiring material that has a coating layer formed from said polyolefin resin composition on an outer circumferential surface of a conductor.

Description

Polyolefin resin composition and wiring material

[0001] The present invention relates to a polyolefin resin composition and a wiring material using the same.

[0002] Electrical and electronic devices, vehicles (including railway vehicles, industrial vehicles, automobiles, etc.), and the like are typically equipped with wiring materials (insulated wires or cables, (electric) cords, optical fiber cores, optical fiber cords, optical cables, etc.) that transport power or transmit information. In addition to having a smooth surface and excellent appearance, such wiring materials are required to have abrasion resistance that prevents exposure of the conductor due to damage (cracks, tears, etc.) to the coating layer even when repeatedly contacted with or rubbed against other components or other wiring materials, while satisfying required properties such as mechanical properties (e.g., tensile elongation and tensile strength) depending on the application.

[0003] The abrasion resistance of wiring materials can be improved by providing (attaching) a protective member to the wiring material. However, this method is not necessarily applicable to modern electrical and electronic devices, where installation space is gradually becoming smaller due to the need for space for the protective member. Therefore, to meet the above-mentioned demands, it is important to first impart abrasion resistance to the wiring material's coating layer itself (the material forming the coating layer). Patent Document 1 proposes a technology for improving scratch resistance to prevent the occurrence of a phenomenon in which scratches on the surface of an insulating layer leave a white mark (scratch whitening). Specifically, Patent Document 1 proposes a "halogen-free composition for wire and cable coating, characterized by having a polyolefin as the base polymer, wherein the polyolefin contains 1 to 30% by mass of a cyclic olefin copolymer," and an "electric wire or cable having a coating made from this composition." Meanwhile, Patent Documents 2 and 3 propose technologies to solve the problem of halogen-free flame-retardant resin compositions, namely, a significant decrease in abrasion resistance. Specifically, Patent Document 2 proposes a resin composition containing "polypropylene (A), a polyolefin composition (B) obtained by polymerizing an ultra-high molecular weight polyolefin and a high- to low-molecular weight polyolefin by a multistage polymerization method, an acid-modified polypropylene (C), and a metal hydrate (D)" in specific mass ratios. Patent Document 3 proposes a composition in which 40 to 100 parts by weight of a metal hydroxide is blended with 100 parts by weight of a blend polymer containing a specific polyolefin and (b) a specific ultra-high molecular weight polyethylene in a specific required ratio. Furthermore, Patent Document 4 proposes a composition in which a base polymer contains a specific ultra-high molecular weight polyethylene and a specific polyethylene or the like in specific mass ratios as a technology for enhancing the heat resistance of an insulated electric wire, although it does not improve the abrasion resistance of the insulated electric wire.

[0004] JP 2010-061828 A JP 2012-229343 A JP 6-076644 A JP 57-103210 A

[0005] In recent years, as electrical and electronic devices, vehicles, and the like have become increasingly complex and sophisticated, the number of wiring materials being installed has increased, and the installation space has become increasingly narrow. Therefore, there is a demand for thinner (lighter) wiring materials themselves. Furthermore, installed wiring materials frequently come into contact with and rub against other components, and thinner wiring materials, in particular, experience reduced abrasion resistance as the coating layer becomes thinner. Therefore, to meet the above-mentioned demands for wiring materials, there is a need for the development of materials that can form coating layers that exhibit sufficient abrasion resistance even when thinned (i.e., the material itself exhibits high abrasion resistance) while maintaining excellent appearance, and that also have improved mechanical properties. However, the technologies described in Patent Documents 1 to 3 are unable to achieve the above-mentioned high abrasion resistance, and Patent Documents 1 to 4 do not even consider the possibility of achieving both high abrasion resistance and mechanical properties that exceed conventional performance while maintaining excellent appearance.

[0006] The present invention aims to provide a polyolefin resin composition that can form a molded article (e.g., a coating layer for wiring material) that exhibits high abrasion resistance and mechanical properties while maintaining an excellent appearance. Another object of the present invention is to provide a wiring material that has a coating layer formed from the polyolefin resin composition and exhibits excellent appearance and high abrasion resistance and mechanical properties.

[0007] The present inventors conducted extensive research into materials for forming the coating layer of wiring materials and discovered that the base resin, rather than the various additives contained in the coating layer, has a greater impact on maintaining appearance while improving abrasion resistance and mechanical properties. Further research led to the discovery that by incorporating 5 to 20% by mass of a cyclic olefin resin and 3 to 20% by mass of an ultra-high molecular weight polyethylene resin composition into the base resin of the material, a molded article can be formed that exhibits high abrasion resistance and high mechanical properties (particularly tensile elongation) while maintaining excellent appearance. Furthermore, the inventors discovered that a base resin comprising a mixture of 5 to 20% by mass of a cyclic olefin resin and 3 to 20% by mass of an ultra-high molecular weight polyethylene resin composition is suitable as a material for forming molded articles (particularly the coating layer of wiring materials). Based on this finding, the present inventors conducted further research and arrived at the present invention.

[0008] That is, the objects of the present invention have been achieved by the following means. <1> A polyolefin resin composition comprising a base resin containing 5 to 20% by mass of a cyclic olefin resin and 3 to 20% by mass of an ultra-high molecular weight polyethylene resin composition. <2> The polyolefin resin composition according to <1>, wherein the ultra-high molecular weight polyethylene resin composition contains an ultra-high molecular weight polyethylene resin with a weight-average molecular weight of 200,000 or more. <3> The polyolefin resin composition according to <1> or <2>, wherein the cyclic olefin resin is a cycloolefin copolymer (COC) or a cycloolefin polymer (COP). <4> The polyolefin resin composition according to any one of <1> to <3>, wherein the polyolefin resin composition is a crosslinked product. <5> A wiring material having a coating layer on the outer peripheral surface of a conductor, wherein the coating layer is formed from the polyolefin resin composition according to any one of <1> to <4>. <6> The wiring material according to <5>, which is an insulated electric wire for vehicles.

[0009] The polyolefin resin composition of the present invention can form a molded article that exhibits high abrasion resistance and high mechanical properties while maintaining an excellent appearance. Furthermore, the wiring material of the present invention has a coating layer formed from the polyolefin resin composition of the present invention, and exhibits excellent appearance and mechanical properties as well as high abrasion resistance. The above and other features and advantages of the present invention will become more apparent from the description below.

[0010] In the present invention, when describing the content, physical properties, etc. of a component by indicating a numerical range, when the upper and lower limits of the numerical range are described separately, any of the upper and lower limits can be appropriately combined to form a specific numerical range. On the other hand, when describing multiple numerical ranges represented using "to", the upper and lower limits forming the numerical range are not limited to the specific combination of upper and lower limits written before and after "to" as a specific numerical range, and can be any numerical range obtained by appropriately combining the upper and lower limits of each numerical range. Note that in the present invention, a numerical range represented using "to" means a range that includes the numerical values ​​written before and after "to" as the upper and lower limits. Furthermore, in the present invention, "(meth)acrylic" represents either acrylic or methacrylic, or both. For example, "alkyl (meth)acrylate" represents either alkyl acrylate or alkyl methacrylate, or both.

[0011] [Polyolefin Resin Composition] The polyolefin resin composition of the present invention (hereinafter sometimes simply referred to as "the resin composition of the present invention") contains a base resin. This base resin contains, as essential resin components, a cyclic olefin resin in a mass proportion of 5 to 20% by mass and an ultra-high molecular weight polyethylene resin composition in a mass proportion of 3 to 20% by mass, and may contain, as optional components, a resin other than the cyclic olefin resin and the ultra-high molecular weight polyethylene resin, or a polymer such as an elastomer (including rubber).

[0012] The resin composition of the present invention, which contains a base resin having the above-described composition, can form a molded article exhibiting high abrasion resistance and high mechanical properties (particularly tensile elongation) while maintaining an excellent appearance, and is particularly suitable for forming a coating layer for a wiring material. Therefore, for example, by using the resin composition of the present invention as a material for forming a coating layer, a wiring material exhibiting excellent appearance and high abrasion resistance and high mechanical properties (particularly tensile elongation) can be realized (manufactured). Thus, the resin composition of the present invention is suitable as a material for forming a coating layer for a wiring material, and is particularly suitable as a material for forming a thin-walled coating layer for, for example, an insulated electric wire for vehicle use, or a thin-walled electric wire that can utilize the above-described excellent properties.

[0013] The polyolefin resin composition of the present invention may be a non-crosslinked polyolefin resin composition (also referred to as a "non-crosslinked polyolefin resin composition") or a crosslinked polyolefin resin composition (also referred to as a "crosslinked polyolefin resin composition"). The necessity of crosslinking is appropriately selected depending on the application and required properties. When used as a material for forming a coating layer of a wiring material, a crosslinked polyolefin resin composition is preferred in that it can improve abrasion resistance to a higher level while maintaining excellent appearance and high mechanical properties, and can also improve heat resistance. Among the polyolefin resin compositions of the present invention, compositions intended to be crosslinked are referred to as "crosslinkable polyolefin resin compositions" to distinguish them from the non-crosslinked polyolefin resin compositions not intended to be crosslinked. Here, the crosslinkable polyolefin resin composition and the non-crosslinked polyolefin resin composition are resin compositions in which a crosslinking reaction is not actively carried out. Typically, the base resin is not crosslinked, but a portion of the base resin may be crosslinked unavoidably or to the extent that does not impair the effects of the present invention. Furthermore, a crosslinked polyolefin resin composition is a resin composition in which a crosslinking reaction has been actively carried out, and although the base resin is usually crosslinked, a portion of the base resin may not be crosslinked depending on the crosslinking conditions, the content of the crosslinking catalyst or crosslinking agent, etc. In the present invention, the term "polyolefin resin composition" is used as a general term including non-crosslinked polyolefin resin compositions, crosslinked polyolefin resin compositions, and crosslinkable polyolefin resin compositions, unless otherwise specified.

[0014] A crosslinked polyolefin resin composition (crosslinked product) is a crosslinked product in which the resin in the base resin is crosslinked, and is prepared by subjecting a crosslinkable polyolefin resin composition to a crosslinking reaction. The crosslinking reaction (crosslinking method) is not particularly limited, and known resin crosslinking methods, such as crosslinking reactions of polyolefins, can be used. Specific examples include electron beam crosslinking, organic peroxide crosslinking, and silane crosslinking. Silane crosslinking is preferred because it can improve abrasion resistance to a higher level while maintaining appearance and mechanical properties, and it can perform crosslinking reactions with high productivity without requiring special equipment. In the present invention, the electron beam crosslinking method refers to a method in which a crosslinkable polymer composition is irradiated with an electron beam to crosslink polymers such as resins and elastomers. On the other hand, the organic peroxide crosslinking method is a chemical crosslinking method in which a crosslinkable polymer composition containing an organic peroxide as a crosslinking catalyst is heated to a temperature above the decomposition temperature of the organic peroxide to directly crosslink polymers with radicals generated from the organic peroxide. The silane crosslinking method, which is a chemical crosslinking method different from the organic peroxide crosslinking method, refers to a method in which a crosslinkable polymer composition containing a silane graft polymer formed by a graft reaction of a silane coupling agent as a crosslinking agent, more preferably a silanol condensation catalyst, is brought into contact with moisture, thereby crosslinking the polymer via the silane coupling agent by causing a silanol condensation reaction of the silane coupling agent.

[0015] A crosslinked polyolefin resin composition has a crosslinked structure in which at least the base resin (constituting (co)polymers, etc.) is crosslinked directly or via a crosslinking agent, etc., and exhibits a high level of balance between appearance, mechanical properties, and abrasion resistance. The crosslinked structure varies depending on the type of crosslinking reaction (crosslinking method) and cannot be clearly and universally defined. The content of the base resin contained in the polyolefin resin composition is the value converted to the content of the base resin before crosslinking, i.e., the content of the base resin in the crosslinkable polyolefin resin composition. In the present invention, with regard to crosslinked polyolefin resin compositions (crosslinked products), those crosslinked by electron beam crosslinking are referred to as "electron beam crosslinked products," those crosslinked by organic peroxide crosslinking are referred to as "organic peroxide crosslinked products," and those crosslinked by silane crosslinking are referred to as "silane crosslinked products" or "silane crosslinked polyolefin resin compositions." Among crosslinkable polyolefin resin compositions, silane-crosslinkable polyolefin resin compositions are particularly referred to as "silane-crosslinked polyolefin resin compositions."

[0016] In terms of abrasion resistance, the resin composition of the present invention is preferably a non-foamed composition. In the present invention, the term "non-foamed composition (non-foamed molded article)" refers to a composition that does not have voids such as bubbles in the composition, in other words, a solid composition, but does not exclude compositions that have unavoidable voids.

[0017] The resin composition of the present invention may be in a shapeless (unmolded) state, in the form of strands or pellets, or in a molded state (molded article).

[0018] Each component used in the present invention will be described below. Each component may be used alone or in combination of two or more.

[0019] [Base Resin] As described above, the base resin contains, as essential resin components, 5 to 20% by mass of a cyclic olefin resin and 3 to 20% by mass of an ultra-high molecular weight polyethylene resin composition. It may also contain, as optional components, resins other than the cyclic olefin resin and the ultra-high molecular weight polyethylene resin composition (sometimes referred to as "other resins" in the present invention). The base resin preferably has crosslinkable moieties. It is not crosslinked in non-crosslinked polyolefin resin compositions, and is crosslinked by the crosslinking method described below in crosslinked polyolefin resin compositions. In particular, when the silane crosslinking method is used as the crosslinking method, the base resin preferably has a moiety capable of undergoing grafting reaction with a silane coupling agent (described below) in its main chain or at its terminal, via radicals generated from an organic peroxide. Examples of crosslinkable moieties and graftable moieties include unsaturated bond moieties in the carbon chain and carbon atoms containing hydrogen atoms. In the present invention, the density of the polymer is a value measured in accordance with "Method A (underwater displacement method)" specified in Japanese Industrial Standards (JIS) K 7112 (1999). In the present invention, the term "polymer" includes homopolymers and copolymers, and unless otherwise specified, refers to a resin, but also includes elastomers and rubbers. In the present invention, even when the base resin contains an elastomer (including rubber), it is referred to as a resin composition, a resin molded product, etc. for convenience, but this does not exclude elastomer compositions and elastomer molded products from the technical scope of the present invention.

[0020] <Cyclic Olefin Resin> The cyclic olefin resin contains a cyclic olefin component as a polymerization component, and is not particularly limited as long as it is a polyolefin-based resin containing a cyclic olefin component in the main chain. Here, the cyclic olefin component includes a component formed by addition polymerization of a cyclic olefin and a component formed by ring-opening polymerization of a cyclic olefin. Examples of the cyclic olefin resin include the resins shown in (1) to (4) below. In the present invention, a resin of a copolymer of a cyclic olefin or a hydrogenated product thereof, such as the resins shown in (2) and (3) below, and a copolymer obtained by copolymerizing these with an unsaturated compound, is referred to as a "cycloolefin copolymer (COC)." A resin of a polymer of a cyclic olefin or a hydrogenated product thereof, such as the resins shown in (1) and (3) below, and a polymer obtained by copolymerizing these with an unsaturated compound, is referred to as a "cycloolefin polymer (COP)." (1) Resins of addition polymers of cyclic olefins or hydrogenated products thereof. (2) Resins of addition copolymers of cyclic olefins and α-olefins or hydrogenated products thereof. (3) Resins of ring-opening (co)polymers of cyclic olefins or hydrogenated products thereof. (4) Resins of polymers obtained by copolymerizing (including graft polymerization) the above polymers or hydrogenated products of (1) to (3) with an unsaturated compound having a polar group, or hydrogenated products thereof.

[0021] The cyclic olefin (compound) in the cyclic olefin resins (1) to (4) is not particularly limited, and examples thereof include the compounds described in (2) Resins of addition copolymers of cyclic olefins and α-olefins or hydrogenated products thereof described below, with compounds represented by the following formula (A1) being preferred, and dicyclic cyclic olefins and tetracyclic cyclic olefins described below being more preferred. The amount of hydrogenation in the hydrogenated products of the cyclic olefin resins (1) to (4) is not particularly limited, and can be set appropriately.

[0022] In the present invention, the cyclic olefin resin is preferably a cycloolefin polymer (COP) rather than a cycloolefin copolymer (COC). As the cyclic olefin resin, (2) a resin of an addition copolymer of a cyclic olefin and an α-olefin or a hydrogenated product thereof, or (3) a resin of a ring-opening (co)polymer of a cyclic olefin or a hydrogenated product thereof is preferred, and (3) a resin of a ring-opening (co)polymer of a cyclic olefin or a hydrogenated product thereof is more preferred.

[0023] In (1) the resin of an addition polymer of a cyclic olefin or a hydrogenated product thereof, the cyclic olefin is as described above, and the addition polymer of a cyclic olefin may appropriately contain a constituent component derived from another copolymerizable unsaturated monomer. The unsaturated monomer component, polymerization method, and polymerization conditions are the same as those in (2) the resin of an addition copolymer of a cyclic olefin and an α-olefin or a hydrogenated product thereof, which will be described later.

[0024] (2) The resin of the addition copolymer of a cyclic olefin and an α-olefin is not particularly limited, and a suitable example is a copolymer containing a constituent component derived from a cyclic olefin represented by the following formula (A1) and a constituent component derived from an α-olefin having 2 to 20 carbon atoms:

[0025] The α-olefin having 2 to 20 carbon atoms is not particularly limited, but is preferably an α-olefin having 2 to 12 carbon atoms, more preferably an α-olefin having 2 to 6 carbon atoms, and even more preferably an α-olefin having 2 or 3 carbon atoms. Examples of the α-olefin having 2 to 20 carbon atoms include ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 3-methyl-1-butene, 3-methyl-1-pentene, 3-ethyl-1-pentene, 4-methyl-1-pentene, 4-methyl-1-hexene, 4,4-dimethyl-1-hexene, 4,4-dimethyl-1-pentene, 4-ethyl-1-hexene, 3-ethyl-1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, and 1-eicosene. One or more types of α-olefins may be used. Of these, the use of ethylene alone is most preferred.

[0026] The cyclic olefin is not particularly limited as long as it is a compound having a cyclic structure containing an unsaturated bond, and for example, a cyclic olefin (compound) represented by the following formula (A1) is preferred.

[0027] In formula (A1), R １ ~R １２ may be the same or different and each represents a hydrogen atom, a halogen atom or a hydrocarbon group. ９ and R １０ , R １１ and R １２ may combine together to form a divalent hydrocarbon group, R ９ or R １０ And, R １１ or R １２ and may form a ring together. n represents 0 or a positive integer, and when n is 2 or more, R ５ ~R ８ may be the same or different in each repeating unit.

[0028] R １ ~R ８ The halogen atom that can be taken as R is not particularly limited, and examples thereof include a fluorine atom, a chlorine atom, and a bromine atom. １ ~R ８ The hydrocarbon group that can be used as R is not particularly limited, and examples thereof include lower alkyl groups (having 1 to 6 carbon atoms) such as methyl, ethyl, propyl, and butyl. １ ~R ８ As the hydrocarbon group that can be used as R ９ ~R １２ Examples of the groups that can be taken as R include aromatic hydrocarbon groups and aralkyl groups. １ ~R ８ The hydrocarbon groups that can be taken as R may be different from each other, may be partially different, or may all be the same. ９ ~R １２ The halogen atom that can be taken as R is not particularly limited, and １ ~R ８ The halogen atoms are the same as those that can be represented by R. ９~R １２ The hydrocarbon group that can be taken as R is not particularly limited, and examples thereof include alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, hexyl, and stearyl; cycloalkyl groups such as cyclohexyl; substituted or unsubstituted aromatic hydrocarbon groups such as phenyl, tolyl, ethylphenyl, isopropylphenyl, naphthyl, and anthryl; and aralkyl groups in which an aryl group is substituted on an alkyl group, such as benzyl, phenethyl, and others. ９ ~R １２ The hydrocarbon groups that can be taken as R may be different from each other, may be partially different, or may all be the same. ９ and R １０ , or R １１ and R １２ When R combines with another group to form a divalent hydrocarbon group, examples of the divalent hydrocarbon group include alkylidene groups such as an ethylidene group, a propylidene group, and an isopropylidene group. ９ or R １０ And, R １１ or R １２ When these rings form a ring together, the ring formed may be a monocyclic ring or a polycyclic ring, a polycyclic ring having a bridge, a ring having a double bond, or a ring formed by a combination of these rings. However, it is preferable that the ring formed is not a norbornane ring, and is also not a norbornene ring. These rings may have a substituent such as a methyl group. n is preferably 0 to 2, and more preferably 0 or 1.

[0029] The cyclic olefin represented by the formula (A1) is not particularly limited, and examples thereof include bicyclic olefins, tricyclic olefins, tetracyclic olefins, and polycyclic olefins.

[0030] Specific examples of the cyclic olefin used in the present invention are described below, but the present invention is not limited to these. Examples of the bicyclic olefins used in the present invention include bicyclo[2.2.1]hept-2-ene (common name: norbornene), 5-methyl-bicyclo[2.2.1]hept-2-ene, 5,5-dimethyl-bicyclo[2.2.1]hept-2-ene, 5-ethyl-bicyclo[2.2.1]hept-2-ene, 5-butyl-bicyclo[2.2.1]hept-2-ene, 5-ethylidene-bicyclo[2.2.1]hept-2-ene, and 5-methyl-bicyclo[2.2.1]hept-2-ene. [2.2.1]hept-2-ene, 5-hexyl-bicyclo[2.2.1]hept-2-ene, 5-octyl-bicyclo[2.2.1]hept-2-ene, 5-octadecyl-bicyclo[2.2.1]hept-2-ene, 5-methylidene-bicyclo[2.2.1]hept-2-ene, 5-vinyl-bicyclo[2.2.1]hept-2-ene, 5-propenyl-bicyclo[2.2.1]hept-2-ene, and the like.

[0031] Among the cyclic olefins used in the present invention, examples of the three-ring cyclic olefin include tricyclo[4.3.0.1 ２，５ ]deca-3,7-diene (trivial name: dicyclopentadiene), tricyclo[4.3.0.1 ２，５ ]dec-3-ene; tricyclo[4.4.0.1 ２，５ ]undeca-3,7-diene or tricyclo[4.4.0.1 ２，５ ]undeca-3,8-diene or a partially hydrogenated product thereof (or an adduct of cyclopentadiene and cyclohexene), tricyclo[4.4.0.1 ２，５ ]undec-3-ene; 5-cyclopentyl-bicyclo[2.2.1]hept-2-ene, 5-cyclohexyl-bicyclo[2.2.1]hept-2-ene, 5-cyclohexenylbicyclo[2.2.1]hept-2-ene, 5-phenyl-bicyclo[2.2.1]hept-2-ene.

[0032] Among the cyclic olefins used in the present invention, examples of 4-ring cyclic olefins include tetracyclo[4.4.0.1 ２，５ .1 ７，１０] dodec-3-ene (also simply called tetracyclododecene), 8-methyltetracyclo[4.4.0.1 ２，５ .1 ７，１０ ] dodec-3-ene, 8-ethyltetracyclo[4.4.0.1 ２，５ .1 ７，１０ ] dodec-3-ene, 8-methylidenetetracyclo[4.4.0.1 ２，５ .1 ７，１０ ] dodec-3-ene, 8-ethylidenetetracyclo[4.4.0.1 ２，５ .1 ７，１０ ] dodec-3-ene, 8-vinyltetracyclo[4.4.0.1 ２，５ .1 ７，１０ ] dodec-3-ene, 8-propenyl-tetracyclo[4.4.0.1 ２，５ .1 ７，１０ ]dodec-3-ene.

[0033] Among the cyclic olefins used in the present invention, examples of polycyclic olefins include 8-cyclopentyl-tetracyclo[4.4.0.1 ２，５ .1 ７，１０ ] dodec-3-ene, 8-cyclohexyl-tetracyclo[4.4.0.1 ２，５ .1 ７，１０ ] dodec-3-ene, 8-cyclohexenyl-tetracyclo[4.4.0.1 ２，５ .1 ７，１０ ] dodec-3-ene, 8-phenyl-cyclopentyl-tetracyclo[4.4.0.1 ２，５ .1 ７，１０ ] dodec-3-ene; tetracyclo[7.4.1 ３，６ .0 １，９ .0 ２，７ ]tetradeca-4,9,11,13-tetraene (also called 1,4-methano-1,4,4a,9a-tetrahydrofluorene), tetracyclo[8.4.1 ４，７ .0 １，１０ .0 ３，８ ]pentadeca-5,10,12,14-tetraene (also known as 1,4-methano-1,4,4a,5,10,10a-hexahydroanthracene); pentacyclo[6.6.1.1 ３，６ .0 ２，７ .0 ９，１４]-4-hexadecene, pentacyclo[6.5.1.1 ３，６ .0 ２，７ .0 ９，１３ ]-4-pentadecene, pentacyclo[7.4.0.0 ２，７ .1 ３，６ .1 １０，１３ ]-4-pentadecene; heptacyclo[8.7.0.1 ２，９ .1 ４，７ .1 １１，１７ .0 ３，８ .0 １２，１６ ]-5-eicosene, heptacyclo[8.7.0.1 ２，９ .0 ３，８ .1 ４，７ .0 １２，１７ .1 １３，ｌ６ ]-14-eicosene; cyclopentadiene.

[0034] In addition to the above-mentioned compounds, the cyclic olefins used in the present invention include the following compounds. For example, examples of 2-ring cyclic olefins include 6-methylnorbornene, 6-ethylnorbornene, 6-n-butylnorbornene, 5-propylnorbornene, 1-methylnorbornene, 7-methylnorbornene, 5,6-dimethylnorbornene, 5-phenylnorbornene, and 5-benzylnorbornene. Furthermore, examples of 4-ring cyclic olefins include 8-hexyltetracyclo-3-dodecene, 2,10-dimethyltetracyclo-3-dodecene, and 5,10-dimethyltetracyclo-3-dodecene.

[0035] The cyclic olefin may be used alone or in combination of two or more. Among the above-mentioned cyclic olefins, bicyclo[2.2.1]hept-2-ene and tetracyclododecene are preferred.

[0036] (2) The method for polymerizing an addition copolymer of a cyclic olefin and an α-olefin and the method for hydrogenating the resulting polymer are not particularly limited and can be carried out according to known methods. The addition copolymer may be a random copolymer or a block copolymer, but a random copolymer is preferred. The polymerization catalyst used in the polymerization method is also not particularly limited, and examples include conventionally known catalysts such as Ziegler-Natta, metathesis, and metallocene catalysts. (2) The addition copolymer of a cyclic olefin and an α-olefin or a hydrogenated product thereof is preferably produced using a metallocene catalyst or a Ziegler-Natta catalyst. Examples of metathesis catalysts include molybdenum or tungsten metathesis catalysts known as catalysts for ring-opening polymerization of cycloolefins (for example, those described in JP-A-58-127728 and JP-A-58-129013). Furthermore, it is preferable that the polymer obtained using a metathesis catalyst is hydrogenated using an inorganic carrier-supported transition metal catalyst or the like, with 90% or more of the double bonds in the main chain and 98% or more of the carbon-carbon double bonds in the aromatic rings of the side chains being hydrogenated.

[0037] (2) The resin of the addition copolymer of a cyclic olefin and an α-olefin may contain, in addition to the components derived from both the α-olefin and the cyclic olefin compound represented by formula (A1), a component derived from another copolymerizable unsaturated monomer, as necessary, within a range that does not impair the object of the present invention. The unsaturated monomer that may be optionally copolymerized is not particularly limited, and examples thereof include hydrocarbon monomers containing two or more carbon-carbon double bonds in one molecule.

[0038] (2) As the resin of the addition copolymer of a cyclic olefin and an α-olefin, a copolymer resin represented by the following formula (A2) obtained by addition polymerization of norbornene or a derivative thereof with the above-mentioned α-olefin is preferred.

[0039]

[0040] In formula (A2), R ２１ , R ２２ and R ２３ represents a hydrogen atom or an alkyl group. ２１ or R２２ The alkyl group that can be taken as R in the above formula (A1) is １ The alkyl group is the same as the alkyl group that can be represented by R ２３ Examples of the alkyl group that can be taken as the cyclic olefin include groups derived from the above α-olefins, such as alkyl groups having 1 to 10 carbon atoms, with alkyl groups having 1 to 4 carbon atoms being preferred. Specific examples of the alkyl group include methyl, ethyl, propyl, butyl, pentyl, hexyl, and octyl groups. Furthermore, m1 and n1 are positive integers and are set appropriately. The cyclic olefin resin represented by the above formula (A2) includes R ２１ , R ２２ and R ２３ are preferably hydrogen atoms, and more preferably are those obtained by addition polymerization of 2-norbornene and ethylene in the presence of a metallocene catalyst.

[0041] (2) As the resin of the addition copolymer of a cyclic olefin and an α-olefin, a cyclic olefin resin obtained by addition polymerization of tetracyclododecene or a derivative thereof with an α-olefin is also preferred, and a resin represented by the following formula (A3) obtained by addition polymerization of tetracyclododecene or a derivative thereof with ethylene is more preferred.

[0042]

[0043] In formula (A3), R ３１ and R ３２ represents a hydrogen atom, a halogen atom, or an alkyl group. ３１ and R ３２ is preferably a hydrogen atom or an alkyl group, more preferably a hydrogen atom. ３１ and R ３２ The alkyl group that can be taken as R in the above formula (A1) is １ In formula (A3), m2 and n2 are positive integers and are set appropriately. As the cyclic olefin resin obtained by addition polymerization of tetracyclododecene or a derivative thereof with an α-olefin, a cyclic olefin resin in which tetracyclododecene or a derivative thereof in the above formula (A3) is replaced with the above four-ring cyclic olefin can also be mentioned as a preferred cyclic olefin resin.

[0044] In the (3) ring-opening (co)polymer of a cyclic olefin or its hydrogenated product, the cyclic olefin is as described above, and the ring-opening (co)addition polymer of a cyclic olefin may appropriately contain a constituent component derived from another copolymerizable unsaturated monomer. The unsaturated monomer component is the same as that in the above-mentioned (2) addition copolymer of a cyclic olefin and an α-olefin or its hydrogenated product. As the resin of the (3) ring-opening (co)polymer of a cyclic olefin, a cyclic olefin resin obtained by ring-opening polymerization of norbornene or tetracyclododecene or a derivative thereof is preferred, and one represented by the following formula (A4) obtained by ring-opening polymerization of norbornene or a derivative thereof is more preferred.

[0045]

[0046] In formula (A4), R ４１ and R ４２ represents a hydrogen atom, a halogen atom, or an alkyl group. ４１ and R ４２ is preferably a hydrogen atom or an alkyl group, more preferably a hydrogen atom. ４１ and R ４２ The alkyl group that can be taken as R in the above formula (A1) is １ In formula (A4), n3 represents the degree of polymerization, and is a positive integer and is set to an appropriate value.

[0047] (4) In the polymer or hydrogenated product thereof obtained by copolymerizing the polymer or hydrogenated product of (1) to (3) above with an unsaturated compound having a polar group, the cyclic olefin is as described above, and the polymer may optionally contain a component derived from another copolymerizable unsaturated monomer. The unsaturated monomer is the same as that in the above-mentioned (2) addition copolymer of a cyclic olefin and an α-olefin or its hydrogenated product. The polar group possessed by the unsaturated compound in the cyclic olefin resin (4) is not particularly limited, and examples thereof include a carboxyl group, an acid anhydride group, an epoxy group, an amide group, an ester group, and a hydroxyl group. The unsaturated compound having such a polar group is not particularly limited, and examples thereof include (meth)acrylic acid, maleic acid, maleic anhydride, itaconic anhydride, glycidyl (meth)acrylate, alkyl (meth)acrylate (C1 to C10) ester, alkyl maleate (C1 to C10) ester, (meth)acrylamide, and 2-hydroxyethyl (meth)acrylate.

[0048] In the present invention, one or more types of cyclic olefin resins can be used. As the cyclic olefin resin containing a cyclic olefin as a copolymerization component, a commercially available resin can also be used. Examples of commercially available cyclic olefin resins include TOPAS (registered trademark) (manufactured by TOPAS ADVANCED POLYMER), APEL (registered trademark) (manufactured by Mitsui Chemicals, Inc.), ZEONEX (registered trademark) (manufactured by Nippon Zeon Co., Ltd.), ZEONOR (registered trademark) (manufactured by Nippon Zeon Co., Ltd.), and ARTON (registered trademark) (manufactured by JSR Corporation).

[0049] <Ultra-High Molecular Weight Polyethylene Resin Composition> In the resin composition of the present invention, an ultra-high molecular weight polyethylene resin composition is combined with the above-mentioned cyclic olefin resin to form an essential component of the base resin. The resin composition of the present invention containing such a base resin can form a molded article exhibiting high abrasion resistance and excellent mechanical properties (particularly tensile elongation) while maintaining excellent appearance. The ultra-high molecular weight polyethylene resin composition is a composition containing an ultra-high molecular weight polyethylene polymer, and includes the ultra-high molecular weight polyethylene polymer itself, compounds containing the ultra-high molecular weight polyethylene polymer, and multi-stage polymers of ultra-high molecular weight polyethylene. For example, compounds containing ultra-high molecular weight polyethylene polymers include compositions containing the ultra-high molecular weight polyethylene polymer, inorganic fillers, oils, etc., and nylon alloys. Furthermore, an example of a multi-stage polymer of ultra-high molecular weight polyethylene is the polyolefin composition (B) described in Patent Document 2, the contents of which are incorporated herein by reference. The content of the ultra-high molecular weight polyethylene polymer in the ultra-high molecular weight polyethylene polymer compound is not particularly limited and can be determined appropriately, for example, from 20 to 95% by mass. The content of the ultra-high molecular weight polyethylene polymer in the multi-stage polymer of ultra-high molecular weight polyethylene is not particularly limited and can be determined appropriately, as described in Patent Document 2, for example.

[0050] Ultra-high molecular weight polyethylene resin (sometimes referred to as UHMWPE or UHPE) refers to a polymer resin with a high molecular weight, primarily composed of ethylene. In the present invention, the weight-average molecular weight of the ultra-high molecular weight polyethylene polymer is not particularly limited, but is preferably 200,000 or more, more preferably 200,000 to 6,000,000, and even more preferably 500,000 to 2,000,000, in terms of appearance, abrasion resistance, and mechanical properties. In the present invention, the density, etc., of the ultra-high molecular weight polyethylene polymer is not particularly limited, but it may have a density equivalent to that of high-density polyethylene and low-density polyethylene. However, in the present invention, even if a polyethylene has a density equivalent to that of high-density polyethylene and low-density polyethylene, if it has a weight-average molecular weight within the above range, the polyethylene is classified as ultra-high molecular weight polyethylene. Here, the weight-average molecular weight is measured in accordance with the method for measuring intrinsic viscosity (JIS K 7367-3:1999).

[0051] The ultra-high molecular weight polyethylene resin contained in the resin composition of the present invention may be one type or two or more types, and preferably contains an ultra-high molecular weight polyethylene resin having a weight average molecular weight of 200,000 or more. The ultra-high molecular weight polyethylene resin composition may be contained as a whole in the base resin or the resin composition of the present invention, or the components may be contained separately in the base resin or the resin composition of the present invention. The ultra-high molecular weight polyethylene resin may be synthesized as appropriate, or a commercially available product may be used. Examples of commercially available products include Hi-Zex Million (registered trademark, manufactured by Mitsui Chemicals, Inc.), Mipelon (registered trademark, manufactured by Mitsui Chemicals, Inc.), and Lubmer (registered trademark, manufactured by Mitsui Chemicals, Inc.).

[0052] <Other Resins> The other resins that may be contained in the polyolefin resin composition of the present invention are not particularly limited as long as they are resins (including elastomers) other than cyclic olefin resins and other than ultra-high molecular weight polyethylene resin compositions, and examples thereof include polyolefin resins other than cyclic olefin resins and other than ultra-high molecular weight polyethylene resins (sometimes referred to as "non-cyclic polyolefin resins" for convenience), acid-modified copolymer resins, ethylene rubber, styrene-based elastomers, acrylic rubber, fluororubber, organic mineral oils, etc. Among these, it is preferable to use an non-cyclic polyolefin resin in combination with a cyclic olefin resin and an ultra-high molecular weight polyethylene resin composition in terms of appearance, mechanical properties, and abrasion resistance.

[0053] (Acyclic Polyolefin Resin) The acyclic polyolefin resin is not particularly limited as long as it is a resin (excluding cyclic olefin resins and ultra-high molecular weight polyethylene resins) composed of a polymer obtained by polymerizing or copolymerizing a compound having an ethylenically unsaturated bond (olefin compound), and known acyclic polyolefin resins used in various resin compositions can be used. For example, an acyclic polyolefin resin composed of a polymer obtained by polymerizing or copolymerizing a linear or branched acyclic olefin can be used. Specific examples of the acyclic polyolefin resin include polyethylene (excluding ultra-high molecular weight polyethylene resins), polypropylene, ethylene-α-olefin copolymers, block copolymers of polypropylene and ethylene-α-olefin resins, polyolefin copolymers having an acid copolymerization component, and polyolefin copolymers having an acid ester copolymerization component. Rubbers or elastomers (excluding ethylene rubber and styrene-based elastomers) of these copolymers can also be used.

[0054] Polyethylene Resin Polyethylene resin (PE) is not particularly limited as long as it is a polymer resin (excluding ultra-high molecular weight polyethylene resin) whose main component is ethylene. Examples include high-density polyethylene (HDPE), low-density polyethylene (LDPE, including linear low-density polyethylene (LLDPE)), and very-low-density polyethylene (VLDPE). Of these, high-density polyethylene and low-density polyethylene are preferred because they provide a good balance of appearance, mechanical properties, and abrasion resistance.

[0055] High density polyethylene (HDPE) has a density of 0.940 g / cm ３ This is the above-mentioned polyethylene, which is also called crystalline hard polyethylene. HDPE includes homopolymers of ethylene (homopolyethylene) and copolymers of ethylene with α-olefins other than ethylene. The α-olefin is not particularly limited, but examples include α-olefins having 3 to 12 carbon atoms. The density and molecular weight of high-density polyethylene are not particularly limited and may be set appropriately.

[0056] Low density polyethylene (LDPE) is 0.910 to 0.925 g / cm ３ Low-density polyethylene is a polyethylene of this type, and usually refers to a copolymer of ethylene and an α-olefin other than ethylene. Examples of α-olefins include the same α-olefins as those used in high-density polyethylene. Among low-density polyethylenes, linear low-density polyethylene (LLDPE) is preferred because it can achieve a good balance of mechanical properties, abrasion resistance, and heat resistance. The density and molecular weight of the low-density polyethylene are not particularly limited and may be set appropriately.

[0057] - Polypropylene Resin - Polypropylene (PP) may be any resin containing a polymer (composition) containing a propylene component as the main component, and includes propylene homopolymers (homopolypropylene: h-PP), random propylene (also referred to as ethylene-propylene random copolymer, r-PP), block propylene (also referred to as ethylene-propylene block copolymer, b-PP), etc. Ethylene-propylene random copolymers refer to those containing approximately 1 to 10% by mass of ethylene components, in which the ethylene components are randomly incorporated into propylene chains. Here, the ethylene component content is a value measured in accordance with the method described in ASTM D3900. Ethylene-propylene block copolymers refer to those containing approximately 5 to 20% by mass of ethylene and ethylene-propylene rubber (EPR) components, in which the ethylene and EPR components exist independently within the propylene component, forming a sea-island structure. When the polyolefin resin composition of the present invention contains polypropylene, it is preferably random propylene, in that it can achieve a good balance of appearance, mechanical properties, and abrasion resistance.

[0058] - Ethylene-α-olefin copolymer resin - The ethylene-α-olefin copolymer resin is preferably a resin of a copolymer of ethylene and an α-olefin having 3 to 12 carbon atoms (excluding those included in the above polyethylene and polypropylene).

[0059] - Polyolefin copolymer resin having an acid copolymerization component - The compound that leads to the acid copolymerization component in the polyolefin copolymer resin having an acid copolymerization component is not particularly limited, and examples thereof include carboxylic acid compounds such as (meth)acrylic acid, etc. Examples of polyolefin copolymer resins having an acid copolymerization component (excluding those contained in polyethylene resins) include ethylene-(meth)acrylic acid copolymer resins.

[0060] Polyolefin copolymer resin having an acid ester copolymerization component: The compound that derives the acid ester copolymerization component in the polyolefin copolymer resin having an acid ester copolymerization component is not particularly limited, and examples thereof include acid ester compounds such as vinyl acetate and (meth)acrylic acid esters. Examples of (meth)acrylic acid esters include, but are not particularly limited to, alkyl (meth)acrylates. The alkyl group of the alkyl (meth)acrylate preferably has 1 to 12 carbon atoms. Examples of polyolefin copolymer resins having an acid ester copolymerization component (excluding those contained in polyethylene resins) include ethylene-vinyl acetate copolymer (EVA) and ethylene-alkyl (meth)acrylate copolymer resins. Specific examples of ethylene-alkyl (meth)acrylate copolymer resins include ethylene-methyl acrylate copolymer (EMA), ethylene-ethyl acrylate copolymer (EEA), and ethylene-butyl acrylate copolymer (EBA) resins. Among these, ethylene-vinyl acetate copolymer and ethylene-methyl acrylate copolymer resins are preferred.

[0061] (Acid-Modified Copolymer Resin) Examples of acid-modified copolymer resins include (co)polymer resins obtained by modifying the above resins or copolymers with an unsaturated carboxylic acid compound (also simply referred to as unsaturated carboxylic acid) or its anhydride. The amount of modification with the unsaturated carboxylic acid in the acid-modified polyolefin resin is not particularly limited, but is preferably 0.1 to 2.0 mass% and more preferably 0.2 to 1.0 mass% relative to the resin (before modification). The unsaturated carboxylic acid (including anhydride) is not particularly limited, and suitable examples include carboxylic acids having an unsaturated bond capable of reacting with the copolymer (e.g., by radical addition reaction). This unsaturated carboxylic acid may have one or two or more carboxy groups. Specific examples of preferred unsaturated carboxylic acids include acrylic acid, methacrylic acid, maleic acid, itaconic acid, and fumaric acid, as well as metal salts or organic salts thereof, and unsaturated carboxylic acid anhydrides such as maleic anhydride, itaconic anhydride, and fumaric anhydride. The unsaturated carboxylic acid used to modify the copolymer may be one or more types. The unsaturated carboxylic acid is preferably maleic anhydride or acrylic acid. Examples of the acid-modified copolymer resin include the acid-modified polypropylene described in Patent Document 2, the contents of which are incorporated herein by reference.

[0062] (Ethylene Rubber) The ethylene rubber is not particularly limited as long as it is a rubber (including elastomers) composed of a copolymer obtained by copolymerizing a compound having an ethylenically unsaturated bond, and known rubbers can be used. Preferred examples of ethylene rubber include binary copolymer rubbers of ethylene and an α-olefin, and ternary copolymer rubbers of ethylene, an α-olefin, and a diene. The diene compound constituting the terpolymer may be either a conjugated diene compound or a non-conjugated diene compound, with non-conjugated diene compounds being preferred. Preferred α-olefins are α-olefins having 3 to 12 carbon atoms. Examples of conjugated diene compounds include butadiene, isoprene, 1,3-pentadiene, and 2,3-dimethyl-1,3-butadiene, with butadiene compounds being preferred. Specific examples of non-conjugated diene compounds include dicyclopentadiene (DCPD), ethylidene norbornene (ENB), and 1,4-hexadiene. As the binary copolymer rubber, ethylene-propylene rubber (EPM) is preferred, and as the ternary copolymer rubber, ethylene-propylene-diene rubber (EPDM) is preferred.

[0063] (Styrene-based elastomer) A styrene-based elastomer refers to a polymer having a constituent component derived from an aromatic vinyl compound in the molecule. Examples of such styrene-based elastomers include block copolymers and random copolymers of conjugated diene compounds and aromatic vinyl compounds, or hydrogenated products thereof. Examples of such styrene-based elastomers include styrene-ethylene-butylene-styrene block copolymer (SEBS), styrene-isoprene-styrene block copolymer (SIS), hydrogenated SIS, styrene-butadiene-styrene block copolymer (SBS), hydrogenated SBS, styrene-ethylene-ethylene-propylene-styrene block copolymer (SEEPS), styrene-ethylene-propylene-styrene block copolymer (SEPS), styrene-butadiene rubber (SBR), and hydrogenated styrene-butadiene rubber (HSBR).

[0064] (Organic mineral oil) In terms of abrasion resistance, it is preferable that the polyolefin resin composition of the present invention does not necessarily require (does not contain) organic mineral oil. In the present invention, "not requiring (does not contain)" a component such as a resin includes both an embodiment in which the component is not contained and an embodiment in which the component may be contained as long as the effect of the present invention is not impaired. The range in which the effect of the present invention is not impaired is not uniquely determined depending on the composition of the polyolefin resin composition, but is, for example, 1 mass % or less in 100 mass % of the base resin. Examples of organic mineral oils include those commonly used in resin compositions, such as paraffinic oils and naphthenic oils.

[0065] (Resin Composition) The base resin contained in the resin composition of the present invention is set to a total proportion of 100% by mass, and contains 5 to 20% by mass of a cyclic olefin resin and 3 to 20% by mass of an ultra-high molecular weight polyethylene resin composition. This base resin allows for the formation of a coating layer that exhibits high abrasion resistance and excellent mechanical properties while maintaining excellent appearance. Therefore, by using this base resin as a material for forming the coating layer of a wiring material, the coating layer can be made thinner and the attachment of a protective member after disposing the wiring material is not necessary. The base resin preferably contains a cyclic olefin resin, an ultra-high molecular weight polyethylene resin composition, and an acyclic polyolefin resin, from the viewpoint of achieving a good balance of excellent appearance, high abrasion resistance, and high mechanical properties. More preferably, the base resin contains a cyclic olefin resin, an ultra-high molecular weight polyethylene resin composition, and a polyethylene resin and / or a polypropylene resin. Even more preferably, the base resin contains a cyclic olefin resin, an ultra-high molecular weight polyethylene resin composition, and at least one of a high-density polyethylene resin, a low-density polyethylene resin, and a polypropylene resin. On the other hand, in terms of abrasion resistance, the base resin preferably does not contain very low density polyethylene (VLDPE, ULDPE) or a polyolefin copolymer resin having an acid ester copolymer component, and more preferably does not contain any of very low density polyethylene, ethylene-vinyl acetate copolymer resin, and ethylene-alkyl (meth)acrylate copolymer resin. In addition, it is also a preferred embodiment that the base resin does not contain an acid-modified resin.

[0066] The content of the cyclic olefin resin in 100% by mass of the base resin is 5 to 20% by mass, from the viewpoint of achieving both high abrasion resistance and high mechanical properties while maintaining an excellent appearance. The content of the cyclic olefin resin is preferably 10 to 20% by mass, and more preferably 10 to 15% by mass, from the viewpoint of achieving a good balance between abrasion resistance and mechanical properties while maintaining an excellent appearance.

[0067] The content of the ultra-high molecular weight polyethylene resin composition in 100% by mass of the base resin is 3 to 20% by mass, from the viewpoint of achieving both high abrasion resistance and high mechanical properties while maintaining an excellent appearance. The content of the ultra-high molecular weight polyethylene resin composition is preferably 5 to 20% by mass, more preferably 5 to 15% by mass, and even more preferably 5 to 10% by mass, from the viewpoint of achieving a good balance between abrasion resistance and mechanical properties while maintaining an excellent appearance.

[0068] In the resin composition of the present invention, the mass ratio of the content of the ultra-high molecular weight polyethylene resin composition to the content of the cyclic olefin resin [content of ultra-high molecular weight polyethylene resin composition / content of cyclic olefin resin] is not particularly limited, but is preferably 0.25 to 2.0, more preferably 0.5 to 1.5, and even more preferably 0.5 to 1.0, in order to achieve a balance between excellent appearance, high abrasion resistance, and high mechanical properties.

[0069] The total content of other resins, etc. in the base resin is not particularly limited, but is determined appropriately depending on the respective contents of the cyclic olefin resin and the ultra-high molecular weight polyethylene resin composition, and is usually the remainder with the base resin being 100% by mass.

[0070] The total content of the acyclic polyolefin resin in 100% by mass of the base resin is not particularly limited, but is preferably 70 to 92% by mass, more preferably 80 to 90% by mass, and even more preferably 80 to 85% by mass, in order to achieve a good balance between appearance, abrasion resistance, and mechanical properties. The content of the low-density polyethylene in 100% by mass of the base resin is not particularly limited and is determined appropriately taking into account the total content of the acyclic polyolefin resin. For example, in order to achieve a good balance between appearance, abrasion resistance, and mechanical properties, it is preferably 0 to 70% by mass, more preferably 20 to 70% by mass, even more preferably 30 to 60% by mass, and especially preferably 40 to 50% by mass. The content of high-density polyethylene in 100% by mass of the base resin is not particularly limited and is determined appropriately taking into account the total content of the acyclic polyolefin resin. For example, from the viewpoint of achieving a good balance between appearance, abrasion resistance, and mechanical properties, it is preferably 0 to 70% by mass, more preferably 10 to 70% by mass. From the viewpoint of achieving high levels of abrasion resistance and mechanical properties while maintaining an excellent appearance, it is even more preferably 10 to 50% by mass, and particularly preferably 10 to 30% by mass. The content of polypropylene in 100% by mass of the base resin is not particularly limited and is determined appropriately taking into account the total content of the acyclic polyolefin resin. For example, from the viewpoint of achieving a good balance between appearance, abrasion resistance, and mechanical properties, it is preferably 0 to 50% by mass, more preferably 5 to 50% by mass, even more preferably 10 to 40% by mass, and particularly preferably 20 to 30% by mass.

[0071] The total content of the polyolefin copolymer resin having an acid copolymerization component, the polyolefin copolymer resin having an acid ester copolymerization component, the acid-modified copolymer resin, the ethylene rubber, and the styrene-based elastomer in 100% by mass of the base resin is not particularly limited, but is preferably 10% by mass or less, and more preferably 0 to 5% by mass, in order to prevent deterioration of any of the properties of appearance, abrasion resistance, and mechanical properties. The respective contents of the polyolefin copolymer resin having an acid copolymerization component, the polyolefin copolymer resin having an acid ester copolymerization component, the acid-modified copolymer resin, the ethylene rubber, and the styrene-based elastomer are appropriately determined taking into account the above total content, and are set, for example, within the same range as the above total content. The content of the organic mineral oil in 100% by mass of the base resin is not particularly limited and can be set appropriately.

[0072] <Inorganic filler> The resin composition of the present invention may contain an inorganic filler. In particular, when it is a silane crosslinked product, it is preferable to contain an inorganic filler from the viewpoint of mechanical strength, and it is more preferable to contain an inorganic filler having on its surface a site capable of chemically bonding with a silanol condensable reactive site of a silane coupling agent by a hydrogen bond, a covalent bond, or an intermolecular bond. Such a site capable of chemical bonding is not particularly limited, but includes an OH group (a hydroxyl group, a water molecule of water of water or crystallization, an OH group such as a carboxyl group), an amino group, an SH group, etc.

[0073] As the inorganic filler, any filler commonly used in resin compositions can be used without any particular limitation. Examples of inorganic fillers include metal hydrates such as compounds having hydroxyl groups or crystal water, such as aluminum hydroxide, magnesium hydroxide, boehmite, calcium carbonate, magnesium carbonate, calcium silicate, magnesium silicate, calcium oxide, magnesium oxide, aluminum oxide, aluminum nitride, aluminum borate whiskers, hydrated aluminum silicate, hydrated magnesium silicate, basic magnesium carbonate, hydrotalcite, and talc. Other examples include boron nitride, silica (crystalline silica, amorphous silica, etc.), carbon black, clay (calcined clay), zinc oxide, tin oxide, titanium oxide, molybdenum oxide, silicone compounds, quartz, zinc borate, white carbon, zinc borate, zinc hydroxystannate, and zinc stannate. Note that some of the above compounds exhibit flame retardant properties in addition to filling properties, but are classified as inorganic fillers in the present invention. Of the inorganic fillers mentioned above, metal hydroxides such as aluminum hydroxide and magnesium hydroxide are preferred, with magnesium hydroxide being preferred because it has a high ability to form a shell when burned and exhibits high flame retardancy.

[0074] The inorganic filler may be surface-treated with a silane coupling agent or the like. Examples include Kisuma 5L and Kisuma 5P (both trade names, magnesium hydroxide, manufactured by Kyowa Chemical Industry Co., Ltd.). The amount of silane coupling agent used to surface-treat the inorganic filler is not particularly limited, but is preferably 3% by mass or less. The inorganic filler is usually contained as a powder or particles. The average particle size is not particularly limited, but is preferably 0.2 to 10 μm. If the average particle size is within the above range, secondary aggregation can be suppressed. The average particle size is determined by dispersing the inorganic filler in alcohol or water and using an optical particle size analyzer such as a laser diffraction / scattering particle size distribution analyzer.

[0075] The content of the inorganic filler in the resin composition of the present invention is not particularly limited and may be determined appropriately. From the viewpoints of appearance, abrasion resistance, and mechanical properties, the content of the inorganic filler is preferably 0 to 130 parts by mass relative to 100 parts by mass of the base resin, more preferably 20 to 120 parts by mass, and even more preferably 50 to 100 parts by mass, from the viewpoint of achieving a high level of balance among appearance, abrasion resistance, and mechanical properties.

[0076] <Flame Retardant> The polyolefin resin composition of the present invention may contain a flame retardant. The flame retardant that may be contained in the resin composition of the present invention is not particularly limited, and any flame retardant commonly used in flame-retardant resin compositions can be used without any particular limitation. Examples of such flame retardants include halogen-based flame retardants. When used in combination with a flame retardant assistant described below, halogen-based flame retardants can effectively exhibit a high flame retardant effect, and the content can be reduced. Therefore, the decrease in abrasion resistance due to the inclusion of a halogen-based flame retardant can be effectively suppressed. The halogen-based flame retardant is not particularly limited as long as it contains a halogen atom. Preferred examples include chlorine-based flame retardants containing chlorine atoms and bromine-based flame retardants containing bromine atoms, and bromine-based flame retardants that have a high flame retardancy enhancement effect when used with the flame retardant assistant described below are preferred. The bromine-based flame retardant is not particularly limited, and any flame retardant commonly used in flame-retardant compositions can be used without any particular limitation. Examples of suitable flame retardants include brominated ethylene bisphthalimide compounds, bisbrominated phenyl terephthalamide compounds, brominated bisphenols (e.g., tetrabromobisphenol A) compounds, 1,2-bis(bromophenyl)ethane compounds, polybromodiphenyl ethers (e.g., decabromodiphenyl ether) compounds, polybromobiphenyls (e.g., tribromophenyl) compounds, hexabromocyclododecane, brominated polystyrene, and hexabromobenzene. Other suitable flame retardants include those described in paragraph

[0020] of JP 2014-132530 A. For brominated flame retardants, the disclosure of JP 2014-132530 A can be referenced as appropriate, and the disclosure is incorporated herein by reference. The chlorine-based flame retardant is not particularly limited, and any of those typically used in flame-retardant compositions can be used without particular limitation. Examples thereof include decachlorododecahydrodimethanocyclooctene compounds and 1,6,7,8,9,14,15,16,17,17,18,18-dodecachloropentacyclo[12.2.1.16,9.02,13.05,10]octadeca-7,15-diene (for example, Dechlorane Plus (trade name) manufactured by HighChem Corporation).

[0077] <Flame Retardant Auxiliary Agent> When the resin composition of the present invention contains a halogen-based flame retardant, it preferably contains a flame retardant auxiliary agent for the halogen-based flame retardant. This flame retardant auxiliary agent is one that, when used in combination with the halogen-based flame retardant, exerts a synergistic effect that exceeds the flame retardant effect exhibited by the halogen-based flame retardant alone. Such a flame retardant auxiliary agent can be any of those commonly used in flame-retardant compositions, and is appropriately selected depending on the halogen-based flame retardant. For example, antimony oxide such as antimony trioxide is preferred. Antimony trioxide can react stepwise with the halogen-based flame retardant to exert a high flame retardant effect.

[0078] The resin composition of the present invention can enhance flame retardancy while maintaining excellent appearance, abrasion resistance, and mechanical properties by containing at least one of an inorganic filler and a flame retardant. To achieve high flame retardancy, it is preferable to contain a flame retardant, and it is more preferable to contain a flame retardant and an inorganic filler or a flame retardant auxiliary.

[0079] <Composition of Flame Retardant, etc.> In the resin composition of the present invention, the content of the flame retardant is preferably 0 to 40 parts by mass, more preferably 5 to 40 parts by mass, and even more preferably 10 to 30 parts by mass, per 100 parts by mass of the base resin, in order to achieve high flame retardancy without impairing the appearance, abrasion resistance, and mechanical properties. The content of the flame retardant aid is preferably 5 to 30 parts by mass, more preferably 5 to 25 parts by mass, and even more preferably 5 to 20 parts by mass, per 100 parts by mass of the base resin, in order to enhance the flame retardant effect of the (halogen-based) flame retardant and further improve the flame retardancy. When the polyolefin resin composition of the present invention contains a flame retardant and a flame retardant aid, the total content is preferably 15 to 60 parts by mass, more preferably 30 to 60 parts by mass, and even more preferably 30 to 50 parts by mass, per 100 parts by mass of the base resin, in order to achieve high flame retardancy without impairing the appearance, abrasion resistance, and mechanical properties. The mass ratio of the content of the flame retardant, particularly the halogen-based flame retardant, to the content of the flame retardant synergist [flame retardant content / flame retardant synergist content] is usually determined appropriately taking into consideration the flame retardancy enhancing effects of the flame retardant and the flame retardant synergist (e.g., the above-mentioned reaction). The mass ratio [flame retardant content / flame retardant synergist content] is, for example, preferably 1 to 3, and more preferably 1.5 to 2.5.

[0080] <Other Components> In addition to the base resin, inorganic filler, flame retardant, and flame retardant aid, the resin composition of the present invention may contain various components (referred to as "other components") such as additives commonly used in resin compositions, within the scope of the present invention. Examples of other components include antioxidants (antioxidants), lubricants, crosslinking agents, crosslinking aids, etc. In addition, the crosslinkable polyolefin resin composition used to prepare the resin composition of the present invention preferably further contains a crosslinking agent, crosslinking aid, crosslinking catalyst, crosslinking accelerator, etc., as appropriate, depending on the type of crosslinking reaction to be applied, and these components will also be described below. The other components that the polyolefin resin composition may contain may each be one type or two or more types.

[0081] (Antiaging Agent) The antioxidant (antioxidant) is not particularly limited, but examples thereof include amine antioxidants, phenol antioxidants, sulfur antioxidants, etc., with phenol antioxidants being preferred. The content of the antioxidant in the polyolefin resin composition is set within a range that does not impair the effects of the present invention, and can be, for example, 0.5 to 15 parts by mass per 100 parts by mass of the base resin.

[0082] (Lubricant) The lubricant is not particularly limited, but examples thereof include silicone compounds, fatty acid metal salts, and fatty acid amides, with silicone compounds being preferred. The content of the lubricant in the polyolefin resin composition is set within a range that does not impair the effects of the present invention, and can be, for example, 0 to 5 parts by mass per 100 parts by mass of the base resin.

[0083] (Silane Coupling Agent) In the present invention, when the crosslinkable polyolefin resin composition is crosslinked by electron beam crosslinking or silane crosslinking, the crosslinkable polyolefin resin composition contains one or more silane coupling agents as crosslinking agents. The silane coupling agent has a grafting reaction site (a functional group such as a group or an ethylenically unsaturated group) that can undergo grafting reaction with a grafting reaction site of a base resin in the presence of a radical generated by irradiation with an electron beam or decomposition of an organic peroxide. The silane coupling agent used in the silane crosslinking method further has a hydrolyzable silyl group (e.g., an alkoxysilyl group) as a silanol condensation reaction site, and it is preferable that this silanol condensation reaction site can react with a chemically bondable site of the inorganic filler.

[0084] Silane coupling agent is not particularly limited, and can be silane coupling agent that has been used in electron beam crosslinking method or silane crosslinking method.Specifically, can be vinyl alkoxysilane such as vinyl trimethoxysilane, vinyl triethoxysilane, vinyl tributoxysilane, vinyl dimethoxyethoxysilane, vinyl dimethoxybutoxysilane, vinyl diethoxybutoxysilane, allyl trimethoxysilane, allyl triethoxysilane, vinyl triacetoxysilane, etc., methacryloxypropyl trimethoxysilane, methacryloxypropyl triethoxysilane, methacryloxypropyl methyl dimethoxysilane, etc. (meth) acryloxyalkoxysilane, etc. Among them, vinyl trimethoxysilane or vinyl triethoxysilane is particularly preferred. The content of the silane coupling agent in the polyolefin resin composition (converted to the content before silane crosslinking (grafting reaction and silanol condensation reaction) in the polyolefin resin composition) is preferably 2 to 15 parts by mass, more preferably 2.5 to 12 parts by mass, and even more preferably 3 to 10 parts by mass, per 100 parts by mass of the base resin.

[0085] (Organic Peroxide) When the crosslinkable polyolefin resin composition is crosslinked by an organic peroxide crosslinking method or a silane crosslinking method, the crosslinkable polyolefin resin composition preferably contains one or more organic peroxides. The organic peroxide generates radicals at least by thermal decomposition, and acts as a catalyst to initiate and promote a crosslinking reaction between resins or a grafting reaction by a radical reaction between a silane coupling agent and a resin. There are no particular limitations on the organic peroxide, and those used in radical polymerization reactions or conventional silane crosslinking methods can be used without particular limitations. Examples of such organic peroxides include those represented by the general formula: R １ -OO-R ２ , R ３ -OO-C(=O)R ４ , R ５ C(=O)-OO(C=O)R ６ In this case, a compound represented by the formula: １ ~R ６ Each of R independently represents an alkyl group, an aryl group, or an acyl group.１ ~R ６ Among these, those in which all groups are alkyl groups, or those in which one is an alkyl group and the remaining is an acyl group, are preferred. Specific examples include benzoyl peroxide, dicumyl peroxide (DCP), 2,5-dimethyl-2,5-di-(tert-butylperoxy)hexane, and 2,5-dimethyl-2,5-di-(tert-butylperoxy)hexyne-3. The content of the organic peroxide in the polyolefin resin composition is not particularly limited, but typically decomposes during crosslinking. The content of the organic peroxide in the crosslinkable polyolefin resin composition can be appropriately determined depending on the crosslinking method. For example, it can be 0.003 to 3 parts by mass per 100 parts by mass of the base resin. The content of the organic peroxide used in preparing the silane-crosslinkable polyolefin resin composition is preferably 0.003 to 0.5 parts by mass, more preferably 0.005 to 0.5 parts by mass, and even more preferably 0.005 to 0.2 parts by mass per 100 parts by mass of the base resin.

[0086] (Silanol Condensation Catalyst) When a crosslinkable polyolefin resin composition is crosslinked by a silane crosslinking method, the crosslinkable polyolefin resin composition preferably contains one or more silanol condensation catalysts. The silanol condensation catalyst functions to promote the condensation reaction of the silanol condensable reactive sites of the silane coupling agent grafted to the resin in the presence of moisture. This condensation reaction crosslinks the resin via the silane coupling agent and, optionally, an inorganic filler. Such silanol condensation catalysts are not particularly limited, and examples thereof include organotin compounds, metal soaps, platinum compounds, etc., with organotin compounds being preferred. Examples of organotin compounds include dibutyltin dilaurate, dioctyltin dilaurate, dibutyltin dioctiate, dibutyltin diacetate, and other organotin compounds. The content of the silanol condensation catalyst in the polyolefin resin composition is not particularly limited, but it usually decomposes during crosslinking. The content of the silanol condensation catalyst in the crosslinkable polyolefin resin composition is not particularly limited and may be determined appropriately. The content of the silanol condensation catalyst is, for example, preferably 0.0001 to 0.5 parts by mass, more preferably 0.001 to 0.2 parts by mass, per 100 parts by mass of the base resin.

[0087] (Crosslinking Auxiliary Agent) When the crosslinkable polyolefin resin composition is crosslinked by an electron beam crosslinking method or an organic peroxide crosslinking method, the crosslinkable polyolefin resin composition may contain one or more crosslinking auxiliary agents. As the crosslinking auxiliary agent, those typically used in electron beam crosslinking methods can be used without any particular limitation. Typically, a polyfunctional compound is used, such as a (meth)acrylate-based polyfunctional compound such as polypropylene glycol di(meth)acrylate or trimethylolpropane tri(meth)acrylate, an allyl-based polyfunctional compound such as triallyl cyanurate, a maleimide-based polyfunctional compound, or a divinyl-based polyfunctional compound. The content of the crosslinking auxiliary in the polyolefin resin composition (converted to the content before the crosslinking reaction) and the content of the crosslinking auxiliary in the crosslinkable polyolefin resin composition can be appropriately set, for example, to 1 to 8 parts by mass per 100 parts by mass of the base resin.

[0088] (Blowing Agent) The crosslinkable polyolefin resin composition forming the polyolefin resin composition of the present invention preferably does not contain a blowing agent for forming foam.

[0089] [Preparation of Polyolefin Resin Composition] The resin composition of the present invention can be prepared by any suitable method, and can be crosslinked as necessary.

[0090] [Preparation of Non-Crosslinked Polyolefin Resin Composition and Crosslinkable Polyolefin Resin Composition] The above-mentioned two compositions can be prepared by mixing or melt-mixing an (uncrosslinked) base resin, optionally an inorganic filler, a flame retardant, a flame retardant aid, other components, and further components appropriate for the crosslinking method. The mixing method is not particularly limited as long as it is a method commonly used in the preparation of rubber or resin compositions. For example, mixing can be performed using various mixing devices such as a single-screw extruder, a twin-screw extruder, a roll, a Banbury mixer, and various kneaders. The mixing conditions, such as the temperature and time of melt mixing (also called kneading), are not particularly limited and can be set appropriately within a temperature range equal to or higher than the melting temperature of the base resin. The mixing temperature is preferably, for example, the melt-mixing conditions of step (1) described below. The order of mixing of the components is not particularly limited. The above components can be mixed (melt) all at once, or the components can be mixed sequentially in an appropriate order. In this way, a crosslinkable (uncrosslinked) polyolefin resin composition in which the components are dispersed (mixed) can be prepared. Regardless of the above preparation method, the crosslinkable polyolefin resin composition to be applied to the silane crosslinking method is preferably prepared by the step (1) described below.

[0091] Both of the above compositions can also be molded into an appropriate shape. When preparing the crosslinkable polyolefin resin composition, it is preferable to mold it before the crosslinking treatment (during or after the preparation). The molding method and molding conditions are appropriately selected depending on the shape and form of the molded product. For example, molding methods include extrusion molding using an extruder, extrusion molding using an injection molding machine, and molding using other molding machines. Extrusion molding is preferred when forming a coating layer for a wiring material, in terms of productivity and the ability to co-extrude with the conductor.

[0092] [Preparation of Crosslinked Polyolefin Resin Composition] The resin composition (crosslinked product) of the present invention can be prepared by subjecting the above-mentioned crosslinkable polyolefin resin composition to the above-mentioned crosslinking reaction treatment. The crosslinkable polyolefin resin composition may be crosslinked in an unmolded state, but is preferably crosslinked after molding by, for example, the above-mentioned molding method. When the polyolefin resin composition of the present invention is a non-foamable resin composition, the production method of the polyolefin resin composition does not include a foaming step (a gas foaming step, a foaming agent decomposition foaming step, etc.).

[0093] When the crosslinkable polyolefin resin composition is subjected to a crosslinking reaction treatment by an electron beam crosslinking method, the crosslinkable polyolefin resin composition prepared as described above is preferably molded into an appropriate shape and then irradiated with an electron beam. The conditions for electron beam irradiation are not particularly limited as long as they can cause the crosslinkable polyolefin resin composition (resin) to undergo a crosslinking reaction. For example, the electron beam irradiation dose can be 1 to 30 Mrad, and the accelerating voltage during irradiation can be 500 to 750 keV.

[0094] When the crosslinkable polyolefin resin composition is subjected to a crosslinking reaction treatment by the organic peroxide crosslinking method, the crosslinkable polyolefin resin composition prepared as described above is preferably molded into an appropriate shape and then heated to a temperature equal to or higher than the decomposition temperature of the organic peroxide. The heating conditions are not particularly limited as long as they are equal to or higher than the decomposition temperature of the organic peroxide contained in the crosslinkable polyolefin resin composition, and the heating time is also not particularly limited. For example, the melt mixing conditions of step (1) described below can be applied as the heating conditions.

[0095] When a crosslinkable polyolefin resin composition is subjected to a crosslinking reaction by the silane crosslinking method, a method is preferred in which the silane crosslinkable polyolefin resin composition containing a base resin to which a silane coupling agent has been grafted is molded, preferably into an appropriate shape, and then brought into contact with moisture. A method for producing a heat-resistant silane-crosslinked polyolefin resin molded product as a crosslinked product by the silane crosslinking method is preferably a production method comprising the following steps (1), (2), and (3).

[0096] Step (1): A step of melt-mixing a base resin containing 5 to 20% by mass of a cyclic olefin resin and 3 to 20% by mass of an ultra-high molecular weight polyethylene resin composition, a silane coupling agent, an organic peroxide, a silanol condensation catalyst, and preferably an inorganic filler to obtain a molten mixture (silane-crosslinkable polyolefin resin composition). Step (2): A step of molding the molten mixture obtained in step (1) to obtain a molded product. Step (3): A step of contacting the molded product obtained in step (2) with water to obtain a molded product of a heat-resistant crosslinked polyolefin resin composition (silane-crosslinked product).

[0097] When carrying out the above step (1), if the entire base resin is melt-mixed in the following step (a), the process comprises steps (a) and (c), and if only a portion of the base resin is melt-mixed in the following step (a), the process comprises steps (a), (b), and (c): Step (a): Melt-mixing all or a portion of the base resin, a silane coupling agent, an organic peroxide, and preferably an inorganic filler at a temperature equal to or higher than the decomposition temperature of the organic peroxide to prepare a silane master batch (silane MB); Step (b): Melt-mixing the remainder of the base resin with a silanol condensation catalyst to prepare a catalyst master batch (catalyst MB); Step (c): Melt-mixing the silane MB with the silanol condensation catalyst or catalyst MB.

[0098] When the remainder of the base resin is melt-mixed as a carrier resin in step (b), the base resin is melt-mixed in an amount of preferably 80 to 99 parts by mass, more preferably 94 to 98 parts by mass, in step (a), and in an amount of preferably 1 to 20 parts by mass, more preferably 2 to 6 parts by mass, in step (b). The base resin mixed in step (a) preferably contains a cyclic olefin resin and an ultra-high molecular weight polyethylene resin composition, and the remainder of the base resin (carrier resin) mixed in step (b) preferably contains a non-cyclic polyolefin resin among other resins.

[0099] The content of each component to be melt-mixed in step (1) is the same as the content in the polyolefin resin composition or crosslinkable polyolefin resin composition described above.

[0100] The melt mixing in step (1) and step (a) can be carried out by appropriately selecting a method commonly used for rubber, plastics, etc., and examples include methods using various mixing devices such as a single-screw extruder, a twin-screw extruder, a roll, a Banbury mixer, or various kneaders. The melt mixing temperature (also referred to as the mixing temperature) is equal to or higher than the decomposition temperature of the organic peroxide, preferably a temperature of the organic peroxide + (1 to 80)°C. While it is difficult to uniquely determine the melt mixing temperature, for example, 80 to 250°C is preferred, and 100 to 240°C is more preferred. Other conditions can be set as appropriate. The mixing time is not particularly limited, and can be, for example, 1 to 25 minutes, preferably 3 to 20 minutes. In step (a), it is preferable to melt mix the above-mentioned components in the absence of a silanol condensation catalyst (e.g., a ratio of 0.01 parts by mass or less per 100 parts by mass of the base resin) to suppress the condensation reaction of the silane coupling agent. In steps (1) and (a), the order of mixing the components during melt mixing is not particularly limited, and the above components can be melt-mixed all at once. However, when an inorganic filler is used, it is preferable to mix the silane coupling agent with the inorganic filler and, if appropriate, with an organic peroxide before melt-mixing with the base resin. This premixing (premixing) can be carried out using a known mixer, kneader, or the like, typically at a temperature below the decomposition temperature of the organic peroxide, preferably 10 to 60°C, more preferably near room temperature (20 to 35°C), for several minutes to several hours, by dry or wet mixing. Preferably, the components are dry-blended at a temperature below the decomposition temperature of the organic peroxide. Premixing allows for a well-balanced formation of a silane coupling agent that bonds strongly to the inorganic filler and a silane coupling agent that bonds weakly to the inorganic filler. In the premixing method, the resulting mixture, all or part of the base resin, and the remaining components are then melt-kneaded, for example, under the melt-mixing conditions described above. The flame retardant and the flame retardant aid may be mixed in at least one of the steps (a) and (b), and are preferably mixed in the step (a).

[0101] The melt-mixing in steps (b) and (c) can be carried out in the same manner as in step (a). However, in step (c), it is preferable that the silane MB and the silanol condensation catalyst are not kept in a mixed state at a high temperature for a long time to avoid a silanol condensation reaction. In step (c), prior to the melt-mixing, the resins can be mixed (e.g., dry-blended) under non-molten conditions, for example, under the pre-mixing conditions described above.

[0102] In step (1), steps (a) to (c) can be carried out simultaneously or successively. In step (1), a crosslinkable polyolefin resin composition (unmolded article) is prepared as a molten mixture.

[0103] Next, step (2) is carried out, in which the resulting molten mixture is molded to obtain a molded product. The molding in step (2) is carried out by any molding method and conditions appropriate to the shape of the molded product, as long as the molten mixture can be molded. The molding method is as described above. This step (2) can be carried out simultaneously with or consecutively to step (c), for example, using an extrusion molding machine. The melt-mixing method and conditions of step (a) can be applied as molding conditions. Step (3) is carried out by contacting the resulting molded product of the crosslinkable polyolefin resin composition with water, causing the silane coupling agent to undergo a silanol condensation reaction (crosslinking reaction). This step (3) can be carried out by a conventional method, and the crosslinking reaction proceeds simply by leaving the molded product at room temperature, for example, at a temperature of about 20 to 25°C. However, the molded product can also be actively brought into contact with water to promote the crosslinking reaction. In this way, a polyolefin resin composition (molded product) containing a base resin crosslinked via a silane coupling agent can be prepared.

[0104] Regarding the silane crosslinking method, the components other than the base resin used (such as a silane coupling agent, an organic peroxide, a silanol condensation catalyst, and an inorganic filler), the steps (1) to (3) in the production method, and the reaction in the silane crosslinking method and the form of the resulting condensation cured product, can be appropriately described in, for example, WO 2016 / 140253 or JP 2017-145370 A, and the contents of these publications are incorporated herein as is as part of the present specification.

[0105] <Uses of Polyolefin Resin Composition> The polyolefin resin composition of the present invention exhibits the above-mentioned excellent properties and can therefore be suitably used as a material for forming a covering layer of wiring materials, particularly wiring materials. It can also be applied to general molded products (sealing materials, packing, etc.). Taking advantage of the above-mentioned excellent properties, the polyolefin resin composition is particularly suitable for applications requiring extremely high abrasion resistance and excellent mechanical properties (tensile elongation). For example, among wiring materials, the polyolefin resin composition is suitable as a material for forming a covering layer of insulated electric wires for automobiles, particularly (very) thin-walled electric wires, which will be described later.

[0106] [Wiring Material] A wiring material using a tubular molded article formed from the polyolefin resin composition of the present invention as a coating layer will be described below. The wiring material of the present invention has a coating layer (including an insulating layer, sheath, etc.) formed from the polyolefin resin composition of the present invention on the outer surface of a conductor. This wiring material has a smooth surface and excellent appearance, and exhibits excellent mechanical properties (tensile elongation) and remarkable abrasion resistance. Preferably, it also has excellent flame retardancy.

[0107] The wiring material of the present invention may have at least one coating layer made of the polyolefin resin composition of the present invention on the outer peripheral surface of the conductor, and other components may be the same as those of a typical wiring material. Examples include an insulated wire having at least one coating layer on the outer peripheral surface of the conductor, and a cable in which a sheath serving as a coating layer is formed on the outer peripheral surface of such an insulated wire or a bundle of such insulated wires. Examples of wiring materials include insulated wires or cables, (electric) cords, optical fiber cores, optical fiber cords, and optical cables. These include wiring materials used for internal or external wiring of electrical and electronic devices, wiring materials installed indoors, and wiring materials installed outdoors. The wiring material of the present invention can be preferably used as an insulated wire or cable for vehicles, a communication wire or cable, a communication optical fiber or optical cable, or a power wire or cable. Among these, the wiring material is particularly suitable as an insulated wire for vehicles, particularly as an (ultra) thin-walled wire (e.g., AESSX class).

[0108] [Coating Layer] The coating layer in the wiring material of the present invention is the same as that in a conventional wiring material, except that it is formed from the polyolefin resin composition of the present invention. Since the polyolefin resin composition of the present invention encompasses both non-crosslinked polyolefin resin compositions and crosslinked polyolefin resin compositions, the wiring material of the present invention encompasses wiring materials having a coating layer formed from a non-crosslinked polyolefin resin composition and wiring materials having a coating layer formed from a crosslinked polyolefin resin composition. The coating layer made from the polyolefin resin composition of the present invention may be provided directly on the outer surface of the conductor, or indirectly via another layer such as an adhesive layer. The coating layer may be a single layer or multiple layers, and in the case of multiple layers, at least one layer must be formed from the polyolefin resin composition of the present invention. The sheath of the cable may also be formed from the polyolefin resin composition of the present invention. The thickness (wall thickness) of the coating layer is determined appropriately depending on the application, etc., and can be set to the same thickness as that of ordinary wiring materials used for each application. For example, for insulated electric wires, etc., it is usually set to about 0.15 to 10 mm (0.4 mm or less for ultra-thin-wall electric wires), and for optical fiber cables, etc., it is usually set to about 0.1 to 10 mm.

[0109] [Conductor] As the conductor, an appropriate conductor can be used depending on the wiring material. For example, a solid-wire conductor or a stranded-wire conductor (including a stranded wire in which tensile strength fibers are longitudinally aligned or twisted together) can be used as appropriate. For example, the conductor used in an insulated electric wire or the like may be a bare wire, a tin-plated wire, or an enamel-coated wire. Examples of metal materials forming the conductor include soft copper, copper alloy, and aluminum. The outer diameter of the conductor is determined appropriately depending on the application, and can be set similarly to that of ordinary wiring materials used for each application. For example, it can be 0.5 to 4.0 mm. On the other hand, examples of conductors used in optical fiber cores and optical fiber cables include conductors made of quartz glass, various plastics, and the like.

[0110] [Method for Producing Wiring Material] The wiring material of the present invention can be produced by any suitable method, but is preferably produced by disposing the polyolefin resin composition of the present invention on the outer peripheral surface of a conductor (molding it into a tubular shape) and appropriately performing a crosslinking reaction treatment. The method for disposing the polyolefin resin composition of the present invention on the outer peripheral surface of a conductor may be any method that can coat the conductor with the polyolefin resin composition, and may include any suitable molding method, such as the molding method described above. The method for disposing the polyolefin resin composition of the present invention on the outer peripheral surface of a conductor (disposing the polyolefin resin composition) can also be carried out as a series of steps (all at once) using an extrusion molding machine, consecutive to the method for preparing the polyolefin resin composition of the present invention (preparing the polyolefin resin composition in the extrusion molding machine). When the polyolefin resin composition of the present invention is a crosslinkable polyolefin resin composition, the crosslinkable polyolefin resin composition disposed on the outer peripheral surface of the conductor is then subjected to a crosslinking reaction treatment. This crosslinking reaction treatment can be carried out using methods and conditions normally applied to each crosslinking method suitable for crosslinkable polyolefin resin compositions, without any particular restrictions, and is specifically as described above. When the polyolefin resin composition of the present invention is crosslinked by the silane crosslinking method, the production method is the same as the above-mentioned production method except that the molten mixture obtained in step (1) is molded onto the outer surface of the conductor using, for example, an extrusion molding machine.

[0111] In this way, the polyolefin resin composition of the present invention can be used to produce wiring materials with a coating layer that have excellent appearance, high abrasion resistance and mechanical properties, and preferably also excellent flame retardancy.

[0112] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0113] Details of each compound used in the examples and comparative examples are shown below. <Base Resin> (Cyclic Olefin Resin) COP1: ZEONOR 1420R (trade name, cycloolefin polymer (ring-opening polymer of tetracyclododecene derivative) COP, manufactured by Zeon Corporation) COP2: ZEONOR 1060R (trade name, cycloolefin polymer (ring-opening polymer of tetracyclododecene derivative) COP, manufactured by Zeon Corporation) COC1: APEL (registered trademark) APL 6509T (trade name, cycloolefin copolymer (addition polymer of norbornene derivative and ethylene) COC, manufactured by Mitsui Chemicals, Inc.) COC2: APEL (registered trademark) APL 6011T (trade name, cycloolefin copolymer (addition polymer of norbornene derivative and ethylene) COC, manufactured by Mitsui Chemicals, Inc.) COC3: APEL (registered trademark) APL 6015T (trade name, cycloolefin copolymer (addition polymer of norbornene derivative and ethylene) COC, manufactured by Mitsui Chemicals, Inc.) (Ultra-high molecular weight polyethylene resin composition) UHPE1: Hi-Zex Million (registered trademark) 030S (trade name, ultra-high molecular weight polyethylene resin, weight average molecular weight of 500,000, manufactured by Mitsui Chemicals, Inc.) UHPE2: LUBMER (registered trademark) L3000 (trade name, ultra-high molecular weight polyethylene resin composition, weight average molecular weight of 200,000 to 1,000,000, manufactured by Mitsui Chemicals, Inc.)

[0114] (Other resins) LLDPE: Evolue (registered trademark) SP1540 (trade name, linear low-density polyethylene, density 0.91 g / cm ３ , manufactured by Prime Polymer Co., Ltd.) HDPE: Evolue (registered trademark)-H SP5505 (trade name, high-density polyethylene polymerized using a metallocene catalyst, density 0.951 g / cm ３, manufactured by Prime Polymer Co., Ltd.) PP: SunAllomer PB222A (trade name, random polypropylene, manufactured by SunAllomer Co., Ltd.)

[0115] <Inorganic filler> Magnesium hydroxide: Magseeds FK-621 (trade name, manufactured by Konoshima Chemical Co., Ltd.) <Other components> Silane coupling agent: KBM-1003 (trade name, trimethoxyvinylsilane, manufactured by Shin-Etsu Silicones Co., Ltd.) Organic peroxide: Perhexa 25B (trade name, 2,5-dimethyl-2,5-di-tert-butylperoxyhexane, decomposition temperature 154°C, manufactured by NOF Corporation) Silanol condensation catalyst: Adekastab OT-1 (trade name, dioctyltin dilaurate, manufactured by ADEKA Corporation) Crosslinking aid: Ogmont T200 (trade name, trimethylolpropane trimethacrylate, manufactured by Shin-Nakamura Chemical Co., Ltd.) Antiaging agent: Irganox 1010 (trade name, Pentaerythritol Tetrakis (3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate), manufactured by BASF) Lubricant: X-22-2125H (trade name, silicone mixture, manufactured by Shin-Etsu Silicones Co., Ltd.)

[0116] Examples 1 to 19 and Comparative Examples 1 to 7 Examples 1 to 19 and Comparative Examples 1 to 7 were each carried out using the components shown in Tables 1 and 2. Specifically, polyolefin resin compositions having the compositions shown in Tables 1 and 2 were prepared by the following production method, and these were extrusion-molded (extrusion-coated) onto the outer peripheral surface of a conductor to produce insulated wires (AESSX-0.3SQf, compliant with Japan Automotive Society Standards (JASO) D 625) having a coating layer formed thereon. In Tables 1 and 2, the numerical values ​​for the mixed amount (content) in each example represent parts by mass unless otherwise specified. Furthermore, a blank space for each component means that the mixed amount of the corresponding component is 0 parts by mass. In Tables 1 and 2, the "content ratio" in the "cyclic olefin resin" column represents the mass ratio of the content of the ultra-high molecular weight polyethylene resin composition to the content of the cyclic olefin resin in each example and comparative example [content of ultra-high molecular weight polyethylene resin composition / content of cyclic olefin resin]. Furthermore, the "total content" in the "other resins" column in Tables 1 and 2 indicates the total content of other resins in each example and comparative example.

[0117] In the examples and comparative examples, the following other components were used depending on the crosslinking method. Note that in Tables 1 and 2, the descriptions of other components and their mixed amounts are omitted, and the total contents are listed in the "Other Components" column. <Silane Crosslinking Method> 2.8 parts by mass of silane coupling agent, 0.1 part by mass of organic peroxide, 0.1 part by mass of silanol condensation catalyst, 1 part by mass of antioxidant, and 1 part by mass of lubricant (5 parts by mass in total) <Non-Crosslinking (Example 15)> 1 part by mass of antioxidant and 1 part by mass of lubricant (2 parts by mass in total) <Electron Beam Crosslinking Method (Example 16)> 3 parts by mass of methacrylate-based polyfunctional compound as crosslinking aid, 1 part by mass of antioxidant, and 1 part by mass of lubricant (5 parts by mass in total) <Organic Peroxide Crosslinking Method (Example 17)> 1 part by mass of organic peroxide as crosslinking agent, 1 part by mass of antioxidant, and 1 part by mass of lubricant (3 parts by mass in total)

[0118] Examples 1 to 14, 18, and 19 and Comparative Examples 1 to 7 Insulated wires were produced by the following silane crosslinking method. In each of the Examples and Comparative Examples, a portion of the base resin was used in step (a), and 5 parts by mass of LLDPE (or HDPE when no LLDPE was contained) was used as the remainder of the base resin in step (b) as a carrier resin for catalyst MB.

[0119] Specifically, 100 parts by mass of base resin was used as the mixing amount, and the inorganic filler (in mass parts shown in Tables 1 and 2), 2.8 parts by mass of silane coupling agent, and 0.1 parts by mass of organic peroxide were dry-mixed at room temperature (25°C). The resulting mixture, a portion of the base resin, 1 part by mass of antioxidant, and 1 part by mass of lubricant were melt-mixed for 5 minutes at a temperature equal to or higher than the decomposition temperature of the organic peroxide (200°C) using a 2L Banbury mixer (manufactured by Nippon Roll Co., Ltd.), in the amounts shown in Tables 1 and 2. The mixture was then discharged at a material discharge temperature of 130°C and pelletized to obtain silane MB (step (a)). The remaining portion of the base resin and 0.1 parts by mass of silanol condensation catalyst were melt-mixed at 150°C using a Banbury mixer (manufactured by Nippon Roll Co., Ltd.), and the mixture was discharged at a material discharge temperature of 130°C to obtain catalyst MB (step (b)). Next, the silane MB obtained in step (a) and the catalyst MB obtained in step (b) were dry-blended at 25°C for approximately 1 minute directly above an extruder (screw diameter: 25 mm, L / D (ratio of effective screw length L to diameter D): 25) to obtain a dry blend. The obtained dry blend was loaded into the extruder and extrusion-coated at a wire speed of 100 m / min (screw rotation speed: 40 rpm) to a finished outer diameter of 1.20 mm (thickness: 0.20 mm) around a stranded conductor (outer diameter: 0.80 mm) made of 19 concentrically twisted annealed copper wires each having a diameter of 0.16 mm (step (2)) under the following extrusion temperature conditions to produce an electric wire precursor. At this time, the dry blend was melt-mixed in the extruder before extrusion molding (step (c)) to prepare a silane-crosslinkable polyolefin resin composition. The extrusion temperature conditions were such that the temperature in the cylinder of the extruder was set to 150 to 190° C., and further the die temperature (molding temperature) was set to 200° C. The wire precursor obtained in this manner was left in an environment of 25° C. and 50% RH for 24 hours (step (3)), thereby bringing the tubular molded product of the crosslinkable polyolefin resin composition into contact with water and causing a silanol condensation reaction, thereby producing an insulated wire having a tubular molded product of the polyolefin resin composition (silane-crosslinked product) as a coating layer.

[0120] Example 15 An insulated wire with a coating layer formed from a non-crosslinked polyolefin resin composition was manufactured. Specifically, the components shown in Table 2 in the amounts shown in Table 2 and the other components used in Example 15 in the above-mentioned mass ratios were charged into a Banbury mixer and melt-mixed at 120 to 200°C for 10 minutes. The mixture was then discharged at a material discharge temperature of 200°C and passed through a feeder rudder to obtain pellets of the non-crosslinked polyolefin resin composition. An insulating coating was formed using the resulting pellets as follows to manufacture an insulated wire. The resulting pellets were introduced into an extruder equipped with a 25 mm diameter screw (ratio of effective screw length L to diameter D: L / D = 25, compression section screw temperature 190°C, head temperature 200°C). The pellets were melted in the extruder and extrusion-coated onto a stranded conductor (outer diameter 0.80 mm) made of 19 concentrically twisted annealed copper wires, each 0.16 mm in diameter, at a wire speed of 100 m / min (screw rotation speed 40 rpm) to a finished outer diameter of 1.20 mm (thickness 0.20 mm). Thus, an insulated wire having a tubular molding of the non-crosslinked polyolefin resin composition as a coating layer was produced.

[0121] Example 16 An insulated electric wire was produced by the electron beam crosslinking method described below. The components shown in Table 2, 3 parts by weight of crosslinking coagent, 1 part by weight of antioxidant, and 1 part by weight of lubricant were charged into a Banbury mixer in the amounts shown in Table 1 and melt-mixed at 120 to 200°C for 10 minutes. The mixture was then discharged at a material discharge temperature of 200°C and passed through a feeder rudder to obtain pellets of a crosslinkable polyolefin resin composition. An insulating coating was formed using the resulting pellets as follows to produce an electric wire precursor. The resulting pellets were introduced into an extruder equipped with a 25 mm diameter screw (ratio of effective screw length L to diameter D: L / D = 25, compression section screw temperature 190°C, head temperature 200°C). The pellets were melted in the extruder and extrusion-coated at a line speed of 100 m / min (screw rotation speed of 40 rpm) around a stranded conductor (outer diameter 0.80 mm) made of 19 concentrically twisted annealed copper wires with a diameter of 0.16 mm, to a finished outer diameter of 1.20 mm (thickness 0.20 mm), to produce an electric wire precursor. The crosslinkable polyolefin resin composition disposed on the outer surface of the conductor was then irradiated with an electron beam at an acceleration voltage of 500 kV to a dose of 10 Mrad. In this way, an insulated electric wire having a tubular molded product (electron beam crosslinked product) of the polyolefin resin composition as a coating layer was produced.

[0122] Example 17 An insulated wire was produced by the organic peroxide crosslinking method described below. The components shown in Table 1, 1 part by mass of antioxidant, and 1 part by mass of lubricant were added to a Banbury mixer in the amounts shown in Table 2 and melt-mixed at 120 to 200°C for 10 minutes. The mixture was then discharged at a material discharge temperature of 200°C and passed through a feeder rudder to obtain pellets of the molten mixture. Next, 1 part by mass of organic peroxide was impregnated into the entire pelletized molten mixture to obtain pellets of a crosslinkable polyolefin resin composition. An insulating coating was formed using the resulting pellets as follows to produce a wire precursor. The resulting pellets were introduced into an extruder equipped with a 25 mm diameter screw (ratio of effective screw length L to diameter D: L / D = 25, compression section screw temperature 190°C, head temperature 200°C). The pellets were melted in the extruder and extrusion-coated at a wire speed of 100 m / min (screw rotation speed of 40 rpm) around a stranded conductor (outer diameter 0.80 mm) made of 19 concentrically twisted annealed copper wires, each 0.16 mm in diameter, to a finished outer diameter of 1.20 mm (thickness 0.20 mm), to produce an electric wire precursor. The electric wire precursor was then held in a chemical crosslinking tube set at 210°C for 15 minutes. In this way, an insulated electric wire having a tubular molded product of the polyolefin resin composition (organic peroxide-crosslinked product) as a coating layer was produced.

[0123] The following tests were carried out on each of the produced insulated wires, and the results are shown in Tables 1 and 2.

[0124] <Evaluation 1: Appearance Test> The surface of each produced insulated wire was observed and evaluated for appearance. An insulated wire whose surface of the coating layer was smooth and free of so-called roughness and had an excellent appearance as an insulated wire was rated "◯" (pass), an insulated wire whose surface had slight irregularities or roughness but had an appearance acceptable for an insulated wire was rated "Δ" (pass), and an insulated wire whose surface had many irregularities or roughness and had an appearance so poor that it was unacceptable for an insulated wire was rated "×" (fail).

[0125] <Evaluation 2: Abrasion Resistance Test> In accordance with Japan Automotive Engineering Society Standard (JASO) D 625, a scrape abrasion test was conducted in which a 0.45 mm diameter stainless steel (SUS) wire was reciprocated on the surface of each insulated wire produced under a load of 7 N. The test was conducted at four test points on the surface of the insulated wire, each forming a central angle of 90°. The number of reciprocal abrasion passes at which the coating layer peeled off and electrical continuity with the conductor was recorded, and the minimum number of reciprocal abrasion passes out of the four was regarded as the abrasion count of the insulated wire. A number of abrasion passes of 200 or more was rated as "◎" (pass), a number of abrasion passes of 150 to less than 200 was rated as "◯" (pass), a number of abrasion passes of 100 to less than 150 was rated as "△" (pass), and a number of abrasion passes of less than 100 was rated as "×" (fail).

[0126] <Evaluation 3: Mechanical Property Test> A tensile test was conducted on the coating layer (tubular piece) obtained by removing the conductor from each of the manufactured insulated wires in accordance with JASO D 625. The tensile test conditions were set to a gauge length of 50 mm and a tensile speed of 200 mm / min, and the tensile elongation (%) of the coating layer was measured. In this test, a tensile elongation of 300% or more was evaluated as "Good" (pass), a tensile elongation of 250% or more but less than 300% was evaluated as "Good" (pass), and a tensile elongation of less than 250% was evaluated as "Poor" (fail).

[0127]

[0128]

[0129] In Tables 1 and 2, in the "Crosslinking Method" column, "Silane" indicates silane crosslinking, "Electron Beam" indicates electron beam crosslinking, "Chemical" indicates organic peroxide crosslinking, and "Non-Crosslinked" indicates no crosslinking (non-crosslinked). The "Other Components" in Tables 1 and 2 are selected depending on the crosslinking method, and are specifically as described above.

[0130] As is clear from the results shown in Tables 1 and 2, the polyolefin resin compositions of Comparative Examples 1 to 7, which contain a base resin that does not contain 5 to 20% by mass of a cyclic olefin resin and 3 to 20% by mass of an ultra-high molecular weight polyethylene resin composition, are inferior in any of appearance, abrasion resistance, and mechanical properties, and are unable to balance these three properties. In contrast, the crosslinked polyolefin resin compositions of Examples 1 to 19, which contain a base resin that contains 5 to 20% by mass of a cyclic olefin resin and 3 to 20% by mass of an ultra-high molecular weight polyethylene resin composition, maintain an excellent appearance while exhibiting high abrasion resistance and remarkable mechanical properties (tensile elongation), regardless of whether crosslinking is performed or not and the crosslinking method.

[0131] While the present invention has been described in connection with embodiments thereof, we do not intend to limit our invention to any of the details of the description unless otherwise specified, and believe that the claims should be construed broadly without departing from the spirit and scope of the invention as set forth in the appended claims.

[0132] This application claims priority based on Japanese Patent Application No. 2024-049204, filed on March 26, 2024, the contents of which are incorporated herein by reference as part of the present specification.

Claims

1. A polyolefin resin composition containing a base resin containing 5 to 20% by mass of a cyclic olefin resin and 3 to 20% by mass of an ultra-high molecular weight polyethylene resin composition.

2. The polyolefin resin composition according to claim 1, wherein the ultra-high molecular weight polyethylene resin composition comprises an ultra-high molecular weight polyethylene resin having a weight average molecular weight of 200,000 or more.

3. The polyolefin resin composition according to claim 1, wherein the cyclic olefin resin is a cycloolefin copolymer (COC) or a cycloolefin polymer (COP).

4. The polyolefin resin composition according to claim 1, wherein the polyolefin resin composition is a crosslinked product.

5. A wiring material having a coating layer on the outer peripheral surface of a conductor, wherein the coating layer is formed from the polyolefin resin composition according to any one of claims 1 to 4.

6. The wiring material according to claim 5, which is an insulated electric wire for use in a vehicle.

Images