JP7067590B2 - Compositions for wire coverings, insulated wires and wire harnesses - Google Patents

Description

The present invention relates to a composition for an electric wire covering material, an insulated electric wire, and a wire harness. It relates to insulated wires and wire harnesses.

Insulated electric wires used in automobiles are sometimes used in places that generate high temperatures, such as around engines, and are required to have high heat resistance. Conventionally, a crosslinked polyvinyl chloride resin or a crosslinked polyolefin resin has been used as a covering material for such an insulated electric wire. As a method for cross-linking these resins, a method of cross-linking with an electron beam has been the mainstream (for example, Patent Document 1).

However, electron beam cross-linking requires an expensive electron beam cross-linking device and the like, and has a problem that the equipment cost is high and the product cost increases. Therefore, silane cross-linking, which can be cross-linked with inexpensive equipment, is attracting attention. A polyolefin composition capable of silane cross-linking, which is used as a covering material for electric wires, cables and the like, is known (for example, Patent Document 2).

Japanese Unexamined Patent Publication No. 2000-294039 Japanese Unexamined Patent Publication No. 2000-21291

Cross-linking with silane is promoted by moisture in the air, as is called water cross-linking. Therefore, in order to prevent an unintended cross-linking reaction from proceeding and the formation of a partially cured product during molding, a method is adopted in which the silane-modified resin, the cross-linking catalyst, and other components are batched and mixed. There is. However, since the cross-linking catalyst and other components are added to the non-cross-linked resin and batch-linked, there is a concern that the degree of cross-linking of the entire resin will be lowered, and the heat resistance and mechanical properties will be lowered.

Further, in recent years, with the spread of hybrid automobiles and the like, electric wires corresponding to high voltage and high current are required, and electric wires having a large electric wire diameter are increasing. For insulated wires with a large diameter, the flexibility of the covering material is required from the viewpoint of ensuring assembly workability. However, when the covering material is made flexible, there are problems that pellets as a raw material and insulated electric wires before cross-linking are fused at the time of manufacturing, and the electric wire covering material is deformed at the time of heating.

INDUSTRIAL APPLICABILITY The present invention is a silane crosslinkable polyolefin-based composition having excellent flame retardancy, and a composition for an electric wire coating material having excellent flexibility, fusion resistance, and heat deformation resistance, and a composition thereof. An object of the present invention is to provide an insulated electric wire and a wire harness.

The composition for an electric wire coating material according to the present invention comprises (A) a silane graft polyolefin obtained by graft-polymerizing a silane coupling agent with a polyolefin, (B) an unmodified polyolefin, and (C) a carboxy group and an ester group. A modified polyolefin having one or more functional groups selected from an acid anhydride group, an amino group, and an epoxy group, (D) a flame retardant, and (E) a cross-linking catalyst, which comprises the above (A). The polyolefin of the silane graft polyolefin before the silane graft has a density of 0.855 to 0.890 g / cm ³ and a melting point of 80 ° C. or higher, and the unmodified polyolefin (B) has a density of 0.855 to 0.950 g / cm. The gist is that it is ³ .

The polyolefin of the (A) silane graft polyolefin before the silane graft has a density of 0.865 to 0.880 g / cm ³ , a melt flow rate of 0.5 to 5 g / 10 minutes at a load of 190 ° C. × 2.16 kg, Shore A. The hardness is 55 to 70, the flexural modulus is 3 to 50 MPa, the melting point is 100 ° C. or higher, and the unmodified polyolefin (B) has a melt flow rate of 0.5 to 5 g / 10 minutes at a load of 190 ° C. × 2.16 kg, bending elasticity. It is preferable that the rate is 3 to 200 MPa and the melting point is 65 ° C. or higher.

The (A) silane grafted polyolefin is contained in an amount of 30 to 90 parts by mass, and the (B) unmodified polyolefin and the (C) modified polyolefin are contained in a total of 10 to 70 parts by mass. With respect to a total of 100 parts by mass of C), 10 to 100 parts by mass of (D-1) metal hydroxide, 10 to 40 parts by mass of (D-2) brominated flame retardant, and 3 as the (D) flame retardant. It contains at least one of 5 to 20 parts by mass of antimony oxide, and 0.01 to 1 part by mass of the (E) cross-linking catalyst with respect to 100 parts by mass of the total of (A), (B) and (C). It is preferable to include a portion.

Further, with respect to a total of 100 parts by mass of the above (A), (B) and (C), 1 to 10 parts by mass of the (F) antioxidant and 1 to 10 parts by mass of the (G) metal inactivating agent. , (H) It is preferable to contain 1 to 10 parts by mass of the lubricant.

Further, with respect to a total of 100 parts by mass of the above (A), (B) and (C), 1 to 15 parts by mass of (I-1) zinc oxide and 1 to 15 parts by mass of an imidazole compound, or (I-). 2) It is preferable to contain any one of 1 to 15 parts by mass of zinc sulfate.

The polyolefin constituting the (A) silane graft polyolefin and the (B) unmodified polyolefin is one or more selected from ultra-low density polyethylene, linear low density polyethylene, and low density polyethylene, respectively. Is preferable.

The gist of the insulated wire according to the present invention is that the insulated wire has a wire covering material obtained by cross-linking the above composition for a wire covering material.

The gist of the wire harness according to the present invention is that it has the above-mentioned insulated electric wire.

According to the composition for an electric wire coating material according to the present invention, it is a silane crosslinkable polyolefin-based composition having excellent flame retardancy, and is an electric wire coating having excellent flexibility, fusion resistance, and heat deformation resistance. A composition for materials can be provided.

In general, the lower the density of polyolefin, the better the flexibility, but the melting point tends to be lower, and it is difficult to achieve both flexibility and fusion resistance and heat deformation resistance. The present invention is excellent in flexibility, fusion resistance, and heat deformation resistance by setting the density and melting point in appropriate ranges.

Next, an embodiment of the present invention will be described in detail.

The composition for an electric wire coating material (hereinafter, also referred to as “the present composition”) according to the present invention comprises (A) a silane graft polyolefin, (B) an unmodified polyolefin, (C) a modified polyolefin, and (D) difficulty. It contains a flame retardant and (E) a cross-linking catalyst. Further, it is preferable to contain (F) an antioxidant, (G) a metal deactivating agent, (H) a lubricant, and (I) a zinc-based stabilizer. The details of each component will be described below.

(A) The silane graft polyolefin is obtained by graft-polymerizing a silane coupling agent with a polyolefin as a main chain to introduce a silane graft chain.

The polyolefin constituting the (A) silane graft polyolefin preferably has a density in the range of 0.855 to 0.890 g / cm ³ . It is more preferably in the range of 0.860 to 0.885 g / cm ³ , and even more preferably in the range of 0.865 to 0.880 g / cm ³ . The lower the density of polyolefin, the easier it is to graft the silane coupling agent and the better the flexibility, but when the density is less than 0.855 g / cm ³ , the melting point tends to be excessively low, and pellets and pre-crosslinked molded products. Is more likely to be fused and deformed during heating. In addition, the heat resistance and wear resistance of the electric wire are likely to decrease, and the resin becomes too soft, so that the kneading property may decrease. On the other hand, if the density of the polyolefin exceeds 0.890 g / cm ³ , the graft ratio may decrease, the crosslink density may decrease, or the flexibility may decrease. The density of polyolefin can be measured according to ASTM D790.

The composition can be crosslinked by contact with steam. At this time, from the viewpoint of preventing the molded products from fusing to each other, the polyolefin constituting the silane graft polyolefin preferably has a melting point of 80 ° C. or higher. It is more preferably 100 ° C. or higher, and even more preferably 120 ° C. or higher. When the melting point of the polyolefin is less than 80 ° C., the pellets before molding and the molded product before crosslinking are likely to be fused, and deformation during heating is likely to occur. The upper limit of the melting point is not particularly limited, but as a polyolefin having excellent flexibility and other physical characteristics, the temperature is generally 135 ° C. or lower in many cases. The melting point of the polyolefin can be measured according to JIS K7121.

In general, the longer the polymer chain is branched and the longer the branched side chain is, the lower the density and the better the flexibility of the polyolefin, but the lower the melting point is. As the polyolefin constituting the silane graft polyolefin, it is appropriate to select a polyolefin having a crystal moiety having few branches and a high density and a long branched side chain and a low density non-crystalline moiety. Polyolefins having a density and a melting point can be obtained. This makes it possible to satisfy fusion resistance and heat deformation resistance while maintaining flexibility.

(A) The polyolefin constituting the silane graft polyolefin has a melt flow rate (hereinafter, also referred to as “MFR”) of 190 ° C. × 2.16 kg in the range of 0.5 to 5.0 g / 10 minutes. preferable. More preferably, it is in the range of 1.0 to 3.0 g / 10 minutes. When the MFR of the polyolefin is 0.5 g / 10 minutes or more, the extrudability is excellent and the productivity is improved. On the other hand, when the MFR is 5 g / 10 minutes or less, the resin shape is easily maintained at the time of molding, and the productivity is improved. The MFR can be measured according to ASTM D1238.

The polyolefin used for the (A) silane graft polyolefin preferably has a shore A hardness in the range of 55 to 70. Further, the polyolefin used for the silane graft polyolefin preferably has a flexural modulus in the range of 3 to 50 MPa. When the shore A hardness and flexural modulus are within the above ranges, the flexibility is excellent and the mechanical properties such as wear resistance are also excellent. The Shore A hardness can be measured according to ASTM D2240, and the flexural modulus can be measured according to ASTM D790.

Examples of the polyolefin used for the (A) silane graft polyolefin include ethylene and propylene homopolymers, and ethylene or propylene and α-olefin copolymers. These may be used alone or in combination of two or more. It is preferable to use at least one selected from polyethylene, polypropylene, an ethylene-butene copolymer, and an ethylene-octene copolymer.

As the polyethylene, it is preferable to use low density polyethylene (LDPE), linear low density polyethylene (LLDPE), ultra low density polyethylene (VLDPE), and metallocene low density polyethylene. These may be used alone or in combination. When these low-density polyethylenes are used, the flexibility of the electric wire is particularly excellent, and the extrusion productivity is improved.

Further, as the above-mentioned polyolefin, a polyolefin elastomer based on an olefin may be used. When a polyolefin elastomer is used, flexibility can be imparted to the coating material. Examples of the polyolefin elastomer include polyethylene-based elastomers (PE elastomers), polypropylene-based elastomers (PP elastomers) and other polyolefin-based thermoplastic elastomers (TPO), ethylene-propylene rubber (EPM, EPR), and ethylene-propylene-diene copolymers. (EPDM, EPT) and the like.

(A) The silane coupling agent used for the silane graft polyolefin is not particularly limited, but for example, vinyl alkoxysilanes such as vinyltrimethoxysilane, vinyltriethoxysilane, and vinyltributoxysilane, and vinyltriacetoxysilane. , Gamma-methacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldimethoxysilane and the like can be exemplified. These may be used alone or in combination of two or more.

The upper limit of the graft amount of the silane coupling agent is preferably 15% by mass or less, more preferably 10% by mass or less, still more preferably 5% by mass or less, from the viewpoint of preventing excessive cross-linking. On the other hand, the lower limit of the graft amount is preferably 0.1% by mass or more, more preferably 1.0% by mass or more, and further preferably 1.5% by mass or more. When the amount of graft is 0.1% or more, when the present composition is crosslinked to form an electric wire coating material, the composition is sufficiently crosslinked and excellent in heat resistance and mechanical strength. The amount of graft is expressed as a percentage of the mass of the grafted silane coupling agent with respect to the mass of the polyolefin before silane grafting.

The silane graft polyolefin (A) preferably has a gel fraction of 85% or more when crosslinked by mixing with a crosslinking catalyst. More preferably, it is 90% or more. When the gel fraction is 85% or more, when the present composition is crosslinked, it is sufficiently crosslinked and excellent in heat resistance and mechanical strength.

The gel fraction of the above silane graft polyolefin can be obtained, for example, by the following measuring method.
A material to which about 0.5 part by mass of a cross-linking catalyst was added to 100 parts by mass of silane graft polyolefin was kneaded at 200 ° C. for 5 minutes, and the obtained mass was press-pressed at 200 ° C. for 3 minutes to a thickness of 1 mm. Mold the sheet. This is crosslinked in a constant temperature and humidity chamber at a humidity of 95% and 60 ° C. for 12 hours, and then dried.
About 0.1 g of a test piece is collected from the obtained molded sheet, the test piece is immersed in a xylene solvent at 120 ° C., taken out after 20 hours, dried, and then the test piece is weighed. The gel fraction is the mass after xylene immersion with respect to the mass before xylene immersion. If a substance other than the silane-grafted polyolefin is contained in the crosslinked product before and after the immersion in xylene, the gel fraction of the silane-grafted polyolefin can be calculated by removing the mass thereof. For example, the cross-linking catalyst is assumed to be contained in the cross-linked product even after being immersed in xylene, and as described later, when the cross-linking catalyst is diluted with a binder resin which is a non-cross-linking component and added, the binder is added after the immersion in xylene. The resin may be calculated assuming that the entire amount is eluted in xylene.

The (A) silane graft polyolefin can be prepared, for example, by adding a free radical generator to a polyolefin and a silane coupling agent and kneading them with a biaxial or uniaxial extrusion kneader. In addition to this, a method of adding a silane coupling agent when polymerizing the polyolefin may be used.
At this time, the blending amount of the silane coupling agent is preferably in the range of 0.5 to 5 parts by mass, more preferably in the range of 3 to 5 parts by mass with respect to 100 parts by mass of the polyolefin. .. When the blending amount of the silane coupling agent is 0.5 parts by mass or more, the polyolefin is sufficiently grafted. On the other hand, when the blending amount of the silane coupling agent is 5 parts by mass or less, it is possible to suppress the excessive progress of the crosslinking reaction at the time of kneading, the generation of gel-like substances can be suppressed, and the productivity and workability are excellent.

Examples of free radical generators include dicumyl peroxide (DCP), benzoyl peroxide, dichlorobenzoyl peroxide, di-tert-butyl peroxide, butyl peracetate, tert-butyl perbenzoate, 2,5-dimethyl-2, Organic peroxides such as 5-di (tert-butylperoxy) hexane can be exemplified. As the free radical generator, dicumyl peroxide (DCP) is preferable.
When dicumyl peroxide (DCP) is used as the free radical generator, it is preferable to set the kneading temperature at 120 ° C. or higher when graft-polymerizing the silane coupling agent on the polyolefin.

The blending amount of the free radical generator is preferably in the range of 0.025 to 0.1 parts by mass with respect to 100 parts by mass of the polyolefin grafted with silane. When the blending amount of the free radical generator is 0.025 parts by mass or more, the grafting reaction proceeds sufficiently. On the other hand, when the blending amount of the free radical generator is 0.1 part by mass or less, it is possible to suppress the excessive progress of the grafting reaction, and the desired silane graft polyolefin can be easily obtained.
The free radical generator may be added by diluting it with an inert substance such as talc or calcium carbonate, or by diluting it with ethylene propylene rubber, ethylene propylene diene rubber, polyolefin or the like and adding it as pellets.

(B) The unmodified polyolefin is a polyolefin composed of a hydrocarbon having no modified group introduced by, for example, graft polymerization or copolymerization. Specific examples thereof include homopolymers of ethylene and propylene, and copolymers of ethylene or propylene and α-olefins. These may be used alone or in combination of two or more. It is preferable to use at least one selected from polyethylene, polypropylene, an ethylene-butene copolymer, and an ethylene-octene copolymer.

As the polyethylene, it is preferable to use low density polyethylene (LDPE), linear low density polyethylene (LLDPE), ultra low density polyethylene (VLDPE), and metallocene low density polyethylene. These may be used alone or in combination. When these low-density polyethylenes are used, the flexibility of the electric wire is particularly excellent, and the extrusion productivity is improved.

Further, as the (B) unmodified polyolefin, a polyolefin elastomer based on an olefin may be used. When a polyolefin elastomer is used, flexibility can be imparted to the coating material. Examples of the polyolefin elastomer include polyethylene-based elastomers (PE elastomers), polypropylene-based elastomers (PP elastomers) and other polyolefin-based thermoplastic elastomers (TPO), ethylene-propylene rubber (EPM, EPR), and ethylene-propylene-diene copolymers. (EPDM, EPT) and the like.

The (B) unmodified polyolefin may be the same as or different from the polyolefin used for the main chain of the (A) silane grafted polyolefin. Excellent compatibility when the same type of polyolefin is used.

(B) As the unmodified polyolefin, those having a density in the range of 0.855 to 0.950 g / cm ³ are used. More preferably, it is in the range of 0.860 to 0.940 g / cm ³ . When the density of the unmodified polyolefin is less than 0.855 g / cm ³ , the melting point tends to be excessively low, the pellets and the molded product before cross-linking tend to be fused, and the deformation during heating tends to occur. In addition, since the resin becomes too soft, the kneadability may decrease. On the other hand, when the density of the unmodified polyolefin exceeds 0.950 g / cm ³ , the flexibility is lowered.

(B) The unmodified polyolefin preferably has a melting point of 65 ° C. or higher. It is more preferably 80 ° C. or higher, and even more preferably 100 ° C. or higher. (B) When the melting point of the unmodified polyolefin is 65 ° C. or higher, the fusion resistance and the heat deformation resistance are excellent. When a polyolefin having a sufficiently high melting point is used as the polyolefin constituting the (A) silane graft polyolefin which is a cross-linking component, the melting point of the (B) unmodified polyolefin is higher than the melting point of the polyolefin constituting the (A) silane graft polyolefin. It may be lowered. The melting point of the polyolefin can be measured according to JIS K7121.

(B) The unmodified polyolefin preferably has an MFR in the range of 0.5 to 5.0 g / 10 minutes. More preferably, it is in the range of 1.0 to 3.0 g / 10 minutes. When the MFR of the polyolefin is 0.5 g / 10 minutes or more, the extrudability is excellent and the productivity is improved. On the other hand, when the MFR is 5 g / 10 minutes or less, the resin shape is easily maintained at the time of molding, and the productivity is improved. The MFR can be measured according to ASTM D1238.

The bending elastic modulus of the unmodified polyolefin is preferably in the range of 3 to 200 MPa. More preferably, it is 10 to 100 MPa. When the flexural modulus is within the above range, the flexibility is excellent. The flexural modulus can be measured according to ASTM D790.

(C) The modified polyolefin is a modified polyolefin having one or more functional groups selected from a carboxy group, an ester group, an acid anhydride group, an amino group and an epoxy group. (C) The modified polyolefin is one in which a functional group is introduced by graft-polymerizing a polymerizable compound having the above functional group on an unmodified base polyolefin composed of one or more α-olefins. Alternatively, the polymerizable compound having the above-mentioned functional group may be polymerized with the polymerizable compound and a polymerizable olefin to introduce a functional group. However, those in which a silanol derivative is introduced, such as methacryloxyalkylsilane, are excluded because they are classified as (A) silane graft polyolefin.

(C) The modified polyolefin has one or more functional groups selected from a carboxy group, an ester group, an acid anhydride group, an amino group, and an epoxy group, and thus exhibits a high interaction with an inorganic component. Since it has a polyolefin chain, it has a high affinity with resin components such as (A) silane grafted polyolefin and (B) unmodified polyolefin. Therefore, the (C) modified polyolefin can be used as a compatibilizer between the resin component and the inorganic component, and is excellent in dispersibility and adhesiveness of the inorganic component.

The polymerizable compound having a carboxy group is not particularly limited as long as it is a compound having a polymerizable group such as a carbon-carbon double bond and a carboxy group in the molecule. For example, acrylic acid, methacrylic acid, crotonic acid, α-chloroacrylic acid, itaconic acid, butentricarboxylic acid, maleic acid, fumaric acid, or derivatives containing these as part of the molecular structure can be mentioned. When these acids form an acid anhydride, an acid anhydride group can be introduced by using the acid anhydride.

As the polymerizable compound having an ester group, an ester compound obtained by reacting the above-mentioned polymerizable compound having a carboxy group with an alcohol can be used. Further, it may be an ester compound obtained by reacting an alcohol having a carbon-carbon double bond with various carboxylic acids. Examples of such a compound include vinyl acetate, vinyl propionate, and the like.

The polymerizable compound having an amino group is not particularly limited as long as it is a compound having a polymerizable group and an amino group such as a carbon-carbon double bond in the molecule. For example, esters obtained by reacting the above-mentioned polymerizable compound having a carboxy group with an alkanolamine, vinylamine, allylamine, or a derivative containing these as part of the molecular structure can be mentioned.

The polymerizable compound having an epoxy group is not particularly limited as long as it is a compound having a polymerizable group such as a carbon-carbon double bond and an epoxy group in the molecule. For example, acid glycidyl esters obtained by reacting the above-mentioned polymerizable compound having a carboxy group with glycidyl alcohol, glycidyl ethers such as vinyl glycidyl ether, allyl glycidyl ether, glycidyloxyethyl vinyl ether, and styrene-p-glycidyl ether, Examples thereof include p-glycidylstyrene and derivatives containing these as part of the molecular structure.

The polymerizable monomer copolymerizable with the above-mentioned polymerizable compound having a functional group is not particularly limited as long as it is a compound having a polymerizable group such as a carbon-carbon double bond in the molecule. For example, an olefin monomer having no functional group such as ethylene or propylene may be used, or a polymerizable monomer having a functional group other than the carboxy group or the epoxy group may be used. These may be used alone or in combination.

The blending amount of the modified polyolefin (C) is preferably 3 to 15 parts by mass with respect to 100 parts by mass in total of the resin components of (A) to (C). More preferably, it is 4 to 10 parts by mass. (C) When the modified polyolefin is contained in an amount of 3 parts by mass or more, the affinity between the resin component and the inorganic component is excellent.

The blending ratio of the resin components (A) to (C) is 30 to 90 parts by mass when the total of (A) to (C) is 100 parts by mass, and 30 to 90 parts by mass of the (A) silane graft polyolefin, and (B) not yet. The total amount of the modified polyolefin and the (C) modified polyolefin is preferably 10 to 70 parts by mass. Within the above range, flexibility is excellent, sufficient crosslink density is obtained, and heat resistance and wear resistance are excellent.

(D) Examples of the flame retardant include metal hydroxides and brominated flame retardants. When a metal hydroxide is used, it can be used as a flame retardant which imparts flame retardancy by itself, and when a brominated flame retardant is used, it is flame retardant when used in combination with antimony trioxide, which is a flame retardant aid. Can be improved. (D) As the flame retardant, either one of the metal hydroxide or the brominated flame retardant may be used, or these may be used in combination. As the flame retardant, a metal hydroxide is preferable from the viewpoint of cost and excellent heat resistance and deformability.

Examples of the metal hydroxide include magnesium hydroxide, aluminum hydroxide, zirconium hydride and the like. Among the above, magnesium hydroxide is preferable from the viewpoint of cost and excellent heat-resistant deformability. As the magnesium hydroxide, either chemically synthesized synthetic magnesium hydroxide or natural magnesium hydroxide obtained by crushing a naturally occurring mineral may be used.

The metal hydroxide preferably has an average particle size of 0.1 to 10 μm, more preferably 0.5 to 5 μm. When the average particle size of the metal hydroxide is 0.1 μm or more, aggregation is unlikely to occur, and when it is 10 μm or less, the dispersibility is excellent. Further, the metal hydroxide may be treated with a surface treatment agent such as a silane coupling agent, a higher fatty acid, or a polyolefin wax for the purpose of improving dispersibility. In the present invention, since the modified polyolefin (C) is contained, the dispersibility of the metal hydroxide is excellent even without surface treatment.

Examples of the bromine-based flame retardant include bromine-based flame retardants having a phthalimide structure such as ethylenebistetrabromophthalimide and ethylenebistribromophthalimide, ethylenebispentabromophenyl, tetrabromobisphenol A (TBBA), hexabromocyclododecane (HBCD), and the like. Examples thereof include TBBA-carbonate oligomer, TBBA-epoxy oligomer, brominated polystyrene, TBBA-bis (dibromopropyl ether), poly (dibromopropyl ether), hexabromobenzene (HBB) and the like. These may be used alone or in combination of two or more. From the viewpoint of having a high melting point and excellent heat resistance, it is preferable to use at least one selected from a phthalimide-based flame retardant or ethylene bispentabromophenyl or a derivative thereof.

Antimony trioxide, which is a flame retardant aid, can be added together with a bromine-based flame retardant to improve flame retardancy. It is preferable to use antimony trioxide having a purity of 99% or more. Antimony trioxide can be used by pulverizing antimony trioxide produced as a mineral and atomizing it. At that time, the average particle size is preferably 3 μm or less, more preferably 1 μm or less. When it is 3 μm or less, the interface strength with the resin is excellent. Further, antimony trioxide may be treated with a surface treatment agent such as a silane coupling agent, a higher fatty acid, or a polyolefin wax for the purpose of improving dispersibility.

When the metal hydroxide is used alone, it is preferable to add it in the range of 10 to 100 parts by mass with respect to a total of 100 parts by mass of the resin components of (A) to (C). When it is 10 parts by mass or more, the flame retardancy is excellent. On the other hand, even if more than 100 parts by mass of the metal hydroxide is added, improvement in flame retardancy cannot be expected, and from the viewpoint of excellent flexibility, the upper limit may be 100 parts by mass.

When a combined system of a brominated flame retardant and an inorganic flame retardant is used as the flame retardant component, the brominated flame retardant and the inorganic flame retardant are mixed in an equivalent ratio, and the brominated flame retardant: the inorganic flame retardant is used. It is preferable to include the flame retardant in the range of 3: 1 to 2: 1.

When a brominated flame retardant and an inorganic flame retardant are used as the flame retardant, 10 to 40 parts by mass of the brominated flame retardant and antimony trioxide are compared with 100 parts by mass of the total resin components of (A) to (C). It is preferable to mix in the range of 5 to 20 parts by mass. When the brominated flame retardant is 10 parts by mass or more, the flame retardant is excellent. On the other hand, even if a bromine-based flame retardant is added in an amount of more than 40 parts by mass, improvement in flame retardancy cannot be expected, and from the viewpoint of excellent flexibility, the upper limit is preferably 100 parts by mass.

When a metal hydroxide and a bromine-based flame retardant are used in combination as the flame retardant, the addition amount of each can be reduced, and the total amount of the resin components (A) to (C) is 100 parts by mass. It is preferable to blend 10 to 50 parts by mass of the metal hydroxide, 5 to 20 parts by mass of the brominated flame retardant, and 5 to 20 parts by mass of antimony trioxide.

The (E) cross-linking catalyst is a silanol condensation catalyst for (A) silane cross-linking of a silane graft polyolefin. Examples of the cross-linking catalyst include carboxylates of metals such as tin, zinc, iron, lead and cobalt, titanic acid esters, organic bases, inorganic acids and organic acids. Specifically, dibutyltin dilaurate, dibutyltin dimarate, dibutyltin bisisooctylthioglycol ester salt, dibutyltin β-mercaptopropionate, dibutyltin diacetate, dioctyltin dilaurate, stannous acetate, first caprylic acid. Tin, lead naphthenate, cobalt naphthenate, barium stearate, calcium stearate, tetrabutyl ester titanate, tetranonyl titanate ester, dibutylamine, hexylamine, pyridine, sulfuric acid, hydrochloric acid, toluenesulfonic acid, acetic acid, stearic acid, Maleic acid and the like can be exemplified. Preferred as the cross-linking catalyst are dibutyltin dilaurate, dibutyltin dimarate, dibutyltin bisisooctylthioglycol ester salt, and dibutyltin β-mercaptopropionate.

When the (E) cross-linking catalyst is mixed with the (A) silane graft polyolefin, the cross-linking reaction proceeds, so it is preferable to mix the cross-linking catalyst immediately before coating the electric wire. At this time, in order to improve the dispersibility of the cross-linking catalyst, it is preferable to mix it with a binder resin in advance and use it as a cross-linking catalyst batch. By using the cross-linking catalyst as a batch of cross-linking catalysts mixed in advance, it is possible to prevent an unexpected cross-linking reaction of the (A) silane graft polyolefin, and the dispersibility of the cross-linking catalyst is excellent, so that the cross-linking reaction proceeds sufficiently. Further, by using it as a cross-linking catalyst batch, it is easy to control the amount of the cross-linking catalyst added.

As the binder resin used in the cross-linking catalyst batch, the polyolefins used in the above-mentioned (A) to (C) can be used. In particular, low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), ultra-low-density polyethylene (VLDPE), and metallocene low-density polyethylene are preferable. When these low-density polyethylenes are used, the flexibility of the electric wire is improved, the extrudability is excellent, and the productivity is improved. Further, for example, a part of (B) unmodified polyolefin may be used as the binder resin.

The cross-linking catalyst batch preferably contains the cross-linking catalyst in the range of 0.5 to 5 parts by mass with respect to 100 parts by mass of the binder resin. More preferably, it is in the range of 1 to 5 parts by mass. If it is 0.5 parts by mass or more, the crosslinking reaction is likely to proceed, and if it is 5 parts by mass or less, the dispersibility of the catalyst is excellent.

The cross-linking catalyst (E) is preferably added in the range of 0.01 to 1.0 parts by mass as the amount of the cross-linking catalyst with respect to a total of 100 parts by mass of the resin components of (A) to (C). , More preferably 0.02 to 0.9 parts by mass. If it is 0.01 part by mass or more, the crosslinking reaction is likely to proceed, and if it is 1.0 part by mass or less, excessive crosslinking can be prevented.

(F) As the antioxidant, a hindered phenolic antioxidant is preferable, and a hindered phenol having a melting point of 200 ° C. or higher is particularly preferable. Examples of hindered phenolic antioxidants include pentaerythritol tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] and thiodiethylenebis [3- (3,5-di-tert-). Butyl-4-hydroxyphenyl) propionate], octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, N, N'-(hexane-1,6-diyl) bis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionamide], 2,4-dimethyl-6- (1-methylpentadecyl) phenol, diethyl [[3,5-bis (1,1-bis) Dimethylethyl) -4-hydroxyphenyl] methyl] phosphonate, 3,3', 3 ", 5,5'5" -hex-tert-butyl-a, a', a "-(methicylene-2,4,6 -Tril) Tri-p-cresol, calcium diethylbis [[[3,5-bis (1,1-dimethylethyl) -4-hydroxyphenyl] methyl] phosphonate], 4,6-bis (octylthiomethyl)- o-cresol, ethylene bis (oxyethylene) bis [3- (5-tert-butyl-4-hydroxy-m-tolyl) propionate], hexamethylene bis [3- (3,5-di-tert-butyl-4) -Hydroxyphenyl) propionate, 1,3,5-tris (3,5-di-tert-butyl-4-hydroxybenzyl) -1,3,5-triazine-2,4,6 (1H, 3H, 5H) -Trione, 1,3,5-tris [(4-tert-butyl-3-hydroxy-2,6-kisilyl) methyl] -1,3,5-triazine-2,4,6 (1H, 3H, 5H) ) -Trione, 2,6-tert-butyl-4- (4,6-bis (octylthio) -1,3,5-triazine-2-ylamino) phenol, 2,6-di-tert-butyl-4- Methylphenol, 2,2'-methylenebis (4-methyl-6-tert-butylphenol), 4,4'-butylidenebis (3-methyl-6-tert-butylphenol), 4,4'-thiobis (3-methyl- 6-tert-butylphenol), 3,9-bis [2- (3- (3-tert-butyl-4-hydroxy-5-methylphenyl) -propinoki) -1,1-dimethylethyl] -2,4 Examples thereof include 8,10-tetraoxaspiro (5,5) undecane. They may be used alone or in combination of two or more. Examples of hindered phenolic antioxidants having a melting point of 200 ° C. or higher include 3,3', 3 ", 5,5'5" -hexa-tert-butyl-a, a', a "-(methicylene-2, 4,6-trill) tri-p-cresol, 1,3,5-tris (3,5-di-tert-butyl-4-hydroxybenzyl) -1,3,5-triazine-2,4,6 ( 1H, 3H, 5H) -trion and the like can be mentioned.

The amount of the (F) antioxidant added is preferably in the range of 1 to 10 parts by mass, more preferably 1 to 5 parts by mass with respect to 100 parts by mass of the total resin components of (A) to (C). .. Within the above range, the antioxidant effect is excellent and bloom and the like can be suppressed.

As the (G) metal inactivating agent, a copper inactivating agent, a chelating agent or the like, which can prevent catalytic oxidation to heavy metals such as copper, can be used. Metal inactivating agents include hydrazide derivatives such as 2,3-bis [3- (3,5-ditert-butyl-4-hydroxyphenyl) propionyl] propionohydrazide and 3- (N-salicyloyl) amino-1. , 2,4-Triazole and other salicylic acid derivatives. As the metal deactivator, a salicylic acid derivative such as 3- (N-salicyloyl) amino-1,2,4-triazole is preferable.

The amount of the (G) metal deactivating agent added is preferably in the range of 1 to 10 parts by mass, more preferably 1 to 5 parts by mass with respect to 100 parts by mass of the total resin components of (A) to (C). be. Within the above range, the effect of preventing copper damage is excellent, and bloom and cross-linking inhibition can be suppressed.

(H) The lubricant is not particularly limited, and either an internal lubricant or an external lubricant may be used. Lubricants include hydrocarbons such as liquid paraffin, paraffin wax and polyethylene wax, fatty acids such as stearic acid, oleic acid and erucic acid, higher alcohols, stearic acid amides, oleic acid amides and erucic acid amides and methylenebis. Examples thereof include alkylene fatty acid amides such as stearic acid amides and ethylene bisstearic acid amides, metal soaps such as stearic acid metal salts, and ester-based lubricants such as stearic acid monoglycerides, stearyl stearate, and cured oils. As the lubricant, it is preferable to use a fatty acid derivative such as erucic acid, oleic acid or stearic acid, or a polyethylene wax from the viewpoint of compatibility with the resin component.

The amount of the lubricant added (H) is preferably in the range of 1 to 10 parts by mass, more preferably 1 to 5 parts by mass with respect to 100 parts by mass of the total of the resin components of (A) to (C). Within the above range, a sufficient lubrication effect can be obtained.

The combination of the (I) component (I-1) zinc oxide and the imidazole compound, or (I-2) zinc sulfide is used as an additive for improving heat resistance and long-term heat resistance. The same effect can be obtained by selecting either (I-2) addition of zinc sulfide alone or (I-1) combination of zinc oxide and an imidazole compound.

The zinc oxide can be obtained, for example, by adding a reducing agent such as coke to zinc ore and oxidizing the zinc vapor generated by firing with air, or by using zinc sulfate or zinc chloride as the salt amount. The production method of zinc oxide is not particularly limited, and zinc oxide may be produced by any method. As for zinc sulfide, a zinc sulfide produced by a known method can be used. The average particle size of zinc oxide and zinc sulfide is preferably 3 μm or less, more preferably 1 μm or less. When the average particle size of zinc oxide and zinc sulfide becomes smaller, the interfacial strength with the resin is improved and the dispersibility is also improved.

As the imidazole-based compound, mercaptobenzimidazole is preferable. Examples of the mercaptobenzimidazole include 2-mercaptobenzimidazole, 2-mercaptomethylbenzimidazole, 4-mercaptomethylbenzimidazole, 5-mercaptomethylbenzimidazole, and zinc salts thereof. 2-Mercaptobenzimidazole and its zinc salt are particularly preferred because they have a high melting point and are stable at high temperatures due to less sublimation during mixing.

As for the component (I), 1 to 15 parts by mass of (I-1) zinc oxide and imidazole compound, respectively, or (I-2) sulfurization with respect to 100 parts by mass of the total of the resin components of (A) to (C). It is preferable to add 1 to 15 parts by mass of zinc. Within the above range, heat resistance and long-term heating resistance are excellent, particles are less likely to aggregate, and dispersibility is excellent.

The composition for electric wire coating material according to the present invention may contain various additives as long as the object of the present invention is not impaired. Examples of the additive include inorganic fillers, pigments, silicone oils, and the like.

For example, when added with an inorganic filler, the hardness of the resin can be adjusted by adding the filler, and the fusion property and the heat deformation resistance can be improved. Examples of the inorganic filler include magnesium oxide and calcium carbonate. From the viewpoint of resin strength and the like, the amount of the inorganic filler added is preferably 30 parts by mass or less with respect to 100 parts by mass in total of the resin components of (A) to (C).

The composition for an electric wire coating material according to the present invention contains, for example, each component (A) to (E) and various additive components added as needed, and is used in a twin-screw extrusion kneader or the like. It can be prepared by kneading, but when the silane graft polyolefin and the crosslinking catalyst are mixed, the crosslinking reaction proceeds due to the moisture in the atmosphere. From the viewpoint of preventing cross-linking reactions during storage and other surplus reactions, it is preferable to mix various components immediately before coating the electric wire. As such a method, it is preferable to prepare a silane graft batch, a flame-retardant batch, and a cross-linking catalyst batch in advance and pelletize them.

The silane graft batch is a batch containing (A) silane graft polyolefin. The flame retardant batch is a batch containing (B) unmodified polyolefin, (C) modified polyolefin, and (D) flame retardant. The cross-linking catalyst batch is a batch containing (E) a cross-linking catalyst and a binder resin. Each component (F) to (I) and various additive components added as needed may be any of a silane graft batch, a flame-retardant batch, and a cross-linking catalyst batch as long as the object of the present invention is not impaired. May be included in.

The insulated wire and wire harness according to the present invention will be described.

In the insulated wire according to the present invention, the outer periphery of the conductor is covered with an insulating layer made of a wire covering material (sometimes simply referred to as a covering material) formed by cross-linking the above-mentioned composition for a wire covering material. The conductor of the insulated wire is not particularly limited in diameter and material of the conductor, and can be appropriately selected depending on the intended use of the insulated wire. Examples of the conductor include copper, copper alloys, aluminum, aluminum alloys and the like. Aluminum or an aluminum alloy is preferable from the viewpoint of reducing the weight of the electric wire. The insulating layer of the electric wire covering material may be a single layer or a plurality of layers of two or more layers.

In the insulated wire of the present invention, the degree of cross-linking of the covering material after cross-linking is preferably 50% or more in terms of gel fraction from the viewpoint of heat resistance. More preferably, the gel content of the coating material is 60% or more. The gel fraction of the covering material of the insulated wire is generally used as an index of the crosslinked state of the crosslinked electric wire. The gel fraction of the dressing can be measured according to, for example, JASO D608-92.

In order to manufacture the insulated wire of the present invention, each batch of the above-mentioned silane graft batch, flame-retardant batch, and cross-linking catalyst batch is usually used, for example, a Bambali mixer, a pressure kneader, a kneading extruder, a twin-screw extruder, a roll, or the like. The composition may be heat-kneaded using the above-mentioned kneader, extruded and coated on the outer periphery of the conductor by using an extrusion molding machine or the like, and then crosslinked.

As a method of cross-linking the covering material, the covering layer of the coated electric wire can be cross-linked by exposing it to steam or water. At this time, it is preferable to carry out within 48 hours within the temperature range of normal temperature to 90 ° C. More preferably, it is 8 to 24 hours in the temperature range of 50 to 80 ° C.

The wire harness of the present invention has the above-mentioned insulated electric wire. The wire harness may be in the form of a single wire bundle in which only the insulated wires are bundled together, or in the form of a mixed wire bundle in which the insulated wires and other insulated wires are bundled in a mixed state. The wire bundle is configured as a wire harness by being bundled with a wire harness protective material such as a corrugated tube or a binding material such as an adhesive tape.

The insulated electric wire according to the present invention can be used for various electric wires such as those for automobiles, devices, information and communication, electric power, ships, and aircraft. In particular, it can be suitably used as an electric wire for automobiles.

According to the international standard ISO 6722, automobile electric wires are classified into classes A to E according to the allowable heat resistant temperature. Since the insulated wire of the present invention is formed from the above-mentioned electric wire coating material composition, it has excellent heat resistance and is most suitable for a battery cable or the like to which a high voltage is applied. It is possible to obtain the characteristics of the D class of.

Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the gist of the present invention.

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited to Examples.

[(A) Silane Graft Polyolefin]
For the silane graft polyolefin (silane graft PE1 to 3, silane graft PP1), vinyl trimethoxysilane (Shinetsu Chemical Co., Ltd.) is used as the base polyolefin using the polyolefins shown below (base PE1 to 5, base PP1) with respect to 100 parts by mass of the polyolefin. A material obtained by dry-blending 1.5 parts by mass of "KBM1003") and 0.15 parts by mass of dicumyl peroxide ("Parkmill D" manufactured by Nichiyu Co., Ltd.) was dry-blended with a single-screw extruder with an inner diameter of 25 mm. Prepared by kneading at 140 ° C.

A material obtained by adding 5 parts by mass of a cross-linking catalyst batch (“Linkron LZ015H” manufactured by Mitsubishi Chemical Corporation) to 100 parts by mass of the above silane graft polyolefin was prepared at 200 ° C. using a “Laboplast Mill” manufactured by Toyo Seiki Co., Ltd. After kneading for × 5 minutes, the obtained mass is compression-pressed at 200 ° C. for 3 minutes to form a sheet having a thickness of 1 mm. This was crosslinked in a constant temperature and humidity chamber at a humidity of 95% and 60 ° C. for 12 hours, and then dried at room temperature for 24 hours.
About 0.1 g of a test piece was collected from the obtained molded sheet and weighed. Then, the test piece was immersed in a xylene solvent at 120 ° C. and taken out after 20 hours, and the taken-out test piece was dried at 100 ° C. × 6 hours, and then the dried test piece was weighed. The mass of the silane graft polyolefin after the xylene immersion with respect to the mass before the xylene immersion is expressed as a percentage, which is shown in Table 1.
Gel fraction% = (mass after soaking in xylene / mass before soaking in xylene) x 100
The cross-linking catalyst contained in the catalyst batch is assumed to be contained in the cross-linked product even after being immersed in xylene, and the gel fraction of the silane graft polyolefin is calculated assuming that the binder resin is completely eluted in xylene after being immersed in xylene. bottom.

The following resins were used as the base polyolefin constituting the silane graft polyolefin. Table 1 shows the density of the base polyolefin before the silane graft, the melting point, the melt flow rate (MFR) at 190 ° C. × 2.16 kg load, the flexural modulus, the shore A hardness, and the gel fraction after the silane graft.
-Base PE1: "INFUSE9107" manufactured by Dow Elastomer
-Base PE2: "INFUSE9807" manufactured by Dow Elastomer
-Base PE3: "INFUSE9507" manufactured by Dow Elastomer
-Base PE4: VLDPE prototype-Base PE5: Dow Elastomer, "Engage 7467"
・ Base PP1: "Novatec EC9" manufactured by Japan Polypropylene Corporation

[(B) Unmodified polyolefin]
The following resins were used as the unmodified polyolefin (unmodified PE1 to 4). The density of each polyolefin is shown in Table 2.
Unmodified PE1: "Engage 7467" manufactured by Dow Elastomer
-Unmodified PE2: "Engage 7256" manufactured by Dow Elastomer
-Unmodified PE3: "INFUSE9107" manufactured by Dow Elastomer
-Unmodified PE4: "Novatec HDHY331" manufactured by Japan Polyethylene Corporation
-PP Elastomer: "Newcon NAR6" manufactured by Japan Polypropylene Corporation

[(C) Modified Polyolefin]
The following resins were used as the modified polyolefins (modified PE1 to 3, modified PP1). The modified PE1 to 3 use polyethylene as the base polyolefin, and the modified PP1 uses polypropylene as the base polyolefin. The modified polyolefins (modified PE1 to 3, modified PP1) have corresponding functional groups by reacting the base polyolefin with the compounds (maleic anhydride, glycidyl methacrylate, methyl methacrylate) shown in parentheses, respectively. This is the introduced resin. In addition, a part of the ester group, the acid anhydride group and the like may exist as a carboxy group by hydrolysis.
-Modified PE1: "Modic AP512P" manufactured by Mitsubishi Chemical Corporation (maleic anhydride modification)
-Modified PE2: "Bond First E" (modified with glycidyl methacrylate) manufactured by Sumitomo Chemical Co., Ltd.
-Modified PE3: "Aklift WH102" (modified with methyl methacrylate) manufactured by Sumitomo Chemical Co., Ltd.
-Modified PP1: "Admer QB550" manufactured by Mitsui Chemicals, Inc. (maleic anhydride modification)

Ingredients other than the above are as follows.
[(D) Flame Retardant]
・ Metal hydroxide 1: Kyowa Chemical Industry Co., Ltd., "Kisma 5" (magnesium hydroxide)
-Metal hydroxide 2: "Granifin H10" (magnesium hydroxide) manufactured by Albemarle Corporation
-Metal hydroxide 3: "C305" (aluminum hydroxide) manufactured by Sumitomo Chemical Co., Ltd.
-Brominated flame retardant 1: "SAYTEX8010" (ethylenebispentabromobenzene) manufactured by Albemarle Corporation
-Brominated flame retardant 1: "SAYTEXBT-93" (ethylenebistetrabromophthalimide) manufactured by Albemarle Corporation
-Antimony trioxide: MSW grade [(E) cross-linking catalyst] manufactured by Yamanaka Sangyo Co., Ltd.
-Crosslink catalyst batch: "Linkron LZ082" manufactured by Mitsubishi Chemical Corporation
[(F) Antioxidant]
-Antioxidant 1: Basf Japan, "Irganox 1010"
-Antioxidant 2: "Irganox 3114" manufactured by BASF Japan Ltd.
[(G) Metal Inactive Agent]
-Metal deactivator: "CDA-1" manufactured by ADEKA Corporation
[(H) Lubricants]
-Glidant: "Alflo P10" (erucic acid amide) manufactured by NOF CORPORATION
[(I) component]
-Zinc oxide: manufactured by HakusuiTech Co., Ltd.-Imidazole compound: manufactured by Kawaguchi Chemical Industry Co., Ltd., "Antage MB" (2-mercaptobenzimidazole)
-Zinc sulfide: "SACHTTLITH HD-S" manufactured by Sachtleben Chemie GmbH.

(Preparation of silane graft batch)
Pellet of silane graft polyolefin was used as a silane graft batch.

(Preparation of cross-linking catalyst batch)
"Linkron LZ082" manufactured by Mitsubishi Chemical Corporation, which is supplied in the form of pellets in advance, was used as a cross-linking catalyst batch. "Linkron LZ082" contains 99 parts by mass of polyethylene (density 0.91 g / cm ³ ) as a binder resin and 1 part by mass of a tin compound as a cross-linking catalyst.

(Preparation of flame retardant batch)
Of the components shown in Tables 3 and 4, the components excluding the silane graft polyolefin, the cross-linking catalyst and the binder resin were added to the twin-screw extrusion kneader and heated and kneaded at 200 ° C. for about 0.1 to 2 minutes to be sufficiently dispersed. Later, it was pelletized to prepare a flame retardant batch.

(Making insulated wires)
Mix the silane graft batch, flame retardant batch, and cross-linking catalyst batch adjusted by the blending amount ratios shown in Tables 3 and 4 in the hopper of the extruder, set the temperature of the extruder to 200 ° C, and perform extrusion processing. gone. In the extrusion process, an insulator having a thickness of 0.7 mm was extruded and coated on a conductor having an outer diameter of 2.4 mm to form a covering material (coating outer diameter: 3.65 mm). Then, an insulated wire was produced by subjecting it to cross-linking treatment for 24 hours in a constant temperature and humidity chamber having a humidity of 95% and 65 ° C.

The obtained composition for electric wire coating material and insulated electric wire were tested for fusion resistance, ISO flame retardancy, gel fraction, ISO long-term heat resistance, ISO wear resistance, flexibility, and ISO heat deformation. evaluated. The evaluation results are shown in Tables 4 and 5. The test methods and evaluation criteria are as follows.

(Fusion resistance)
The insulated wire before cross-linking, in which an insulator is extruded and coated on the above-mentioned wire conductor to form a covering material, is wound on an iron reel having an outer diameter of 30 mm for 300 m and cross-linked in a constant temperature and humidity chamber at a humidity of 95% and 65 ° C. for 24 hours. Processed. The insulated wires after cross-linking were rewound on plastic reels, and the presence or absence of fusion marks that appeared when the wires were fused to each other was visually confirmed. Those with no fusion marks were rated as "○", and those with no fusion marks were rated as "×".

(ISO flame retardant)
In accordance with ISO 6722, the cross-linked insulated wire that extinguished the fire within 70 seconds was marked as "○", and the cross-linked insulated wire that did not extinguish within 70 seconds was marked as "x".

(Gel fraction)
The gel fraction was measured according to JASO D608-92. That is, a sample of about 0.1 g was collected from the crosslinked insulating wire coating material and weighed. This is placed in a test tube, 20 ml of xylene is added, and the mixture is heated in a constant temperature oil bath at 120 ° C. for 24 hours. Then, the sample was taken out, dried in a dryer at 100 ° C. for 6 hours, allowed to cool to room temperature, and weighed. The mass after the test with respect to the mass before the test expressed as a percentage was defined as the gel fraction. Those with a gel fraction of 50% or more were rated as "○", those with a gel fraction of 60% or more were rated as "◎", and those with a gel fraction of less than 50% were rated as "x".

(ISO long-term heating property)
According to ISO 6722, the crosslinked insulated wire was left in a constant temperature bath at 125 ° C. or 150 ° C. for 3000 hours, and then a withstand voltage test of 1 kV for 1 minute was performed. In the withstand voltage test after leaving in a constant temperature bath at 125 ° C, those without dielectric breakdown passed "○", those with dielectric breakdown failed "×", and withstand voltage after leaving in a constant temperature bath at 150 ° C. Those that did not break down in the test were also given a better "◎".

(ISO wear resistance)
In accordance with ISO 6722, an iron wire with an outer diameter of 0.45 mm is pressed against the crosslinked insulated wire with a load of 7 N and reciprocated at a speed of 55 times / minute, and the iron wire and copper, which is a conductor, become conductive. The number of times up to was measured. 700 times or more was evaluated as "○", 1000 times or more was evaluated as "◎", and less than 700 times was evaluated as "×".

(Flexibility)
Three-point bending flexibility was evaluated using Shimadzu Autograph AG-01 with reference to JIS K7171. That is, the crosslinked insulated wires were cut to a length of 100 mm, three wires were arranged in a horizontal row, and the tips were fixed with polyvinyl chloride tape to obtain a test piece. The center between the columns was pushed from above at a speed of 1 mm / min with respect to the test piece set on the jig with a space between the columns of 50 mm, and the maximum load was measured.
When the maximum load was 3N or less, it was evaluated as "○", when the maximum load was 2N or less, it was evaluated as "◎", and when the maximum load exceeded 3N, it was evaluated as "×".

(ISO heat deformability)
In accordance with ISO 6722, a blade with a width of 0.7 mm at the tip is pressed against the crosslinked insulated wire with a load of 190 g, left in a constant temperature bath at 150 ° C. for 4 hours, and then the insulated wire is placed in 1% saline solution. A withstand voltage test of 1 kV and 1 minute was performed. Those that did not break down were rated as "○", and those that did not break down were rated as "×". If the result is acceptable, the insulation coating is taken out from the constant temperature bath for the cumulative thickness in the same direction (for example, 0.7 × 2 = 1.4 mm in the case of 0.7 mm on one side) before being placed in the constant temperature bath. The ratio of the thickness after that was used as the residual ratio, and the one with a residual ratio of 75% or more was rated as "◎".

From Tables 3 and 4, in Comparative Examples 1, 2 and 5, since the melting point of the polyolefin constituting the silane graft polyolefin was less than 80 ° C., the electric wires were fused to each other at the time of crosslinking. In Comparative Example 3, since the density of the polyolefin constituting the silane graft polyolefin is larger than 0.890 g / cm ³ , the gel fraction is low and the flexibility is inferior. In Comparative Example 4, since the density of the unmodified polyolefin is higher than 0.950 g / cm ³ , the flexibility is inferior. Comparative Example 5 is inferior in flame retardancy because it does not contain a flame retardant, and is also inferior in wear resistance because it contains a small amount of inorganic components. Comparative Example 6 does not contain a cross-linking catalyst, so that it is not cross-linked.
On the other hand, according to the embodiment satisfying the configuration of the present invention, it is excellent in flexibility, fusion resistance, and heat deformation resistance. Further, Examples 4 and 5 to which the component (I) is added are excellent in long-term heating resistance as compared with those to which the component (I) is not added.

Claims (18)

(A) Silane grafted polyolefin obtained by graft-polymerizing a silane coupling agent with a polyolefin (B) Unmodified polyolefin (C) One selected from a carboxy group, an ester group, an acid anhydride group, an amino group and an epoxy group. Alternatively, it contains a modified polyolefin having two or more functional groups (D) a flame retardant (E) and a cross-linking catalyst.
The polyolefin of the (A) silane graft polyolefin before the silane graft has a density of 0.865 to 0.890 g / cm ³ and a melting point of 80 ° C. or higher.
The (B) unmodified polyolefin has a density of 0.860 to 0.950 g / cm ³ .
30 to 90 parts by mass of the (A) silane graft polyolefin contains 10 to 70 parts by mass of the (B) unmodified polyolefin and the (C) modified polyolefin in total.
As the flame retardant (D), with respect to a total of 100 parts by mass of (A), (B) and (C).
(D-1) 10 to 100 parts by mass of metal hydroxide,
(D-2) 10 to 40 parts by mass of brominated flame retardant and 5 to 20 parts by mass of antimony trioxide,
A composition for an electric wire coating material, which comprises at least one of the above. As the (D) flame retardant,
The composition for an electric wire coating material according to claim 1, wherein the composition (D-1) contains at least a metal hydroxide. The composition for an electric wire coating material according to claim 2, wherein the (D-1) metal hydroxide is particles having an average particle size of 0.1 to 10 μm and not subjected to surface treatment. .. As the (D) flame retardant,
With the (D-1) metal hydroxide
The (D-2) brominated flame retardant and antimony trioxide
The composition for an electric wire covering material according to claim 2 or 3, wherein the composition comprises both of the above. As the flame retardant (D), with respect to a total of 100 parts by mass of (A), (B) and (C).
10 to 50 parts by mass of the (D-1) metal hydroxide, and
10 to 20 parts by mass of the (D-2) brominated flame retardant and 5 to 20 parts by mass of antimony trioxide,
The composition for an electric wire covering material according to claim 4, wherein the composition comprises. Claim 1 of the above (D-2), wherein the brominated flame retardant and the antimony trioxide are contained in an equivalent ratio of brominated flame retardant: antimony trioxide = 3: 1 to 2: 1. The composition for an electric wire covering material according to any one of 5 to 5. The polyolefin of the (A) silane graft polyolefin before the silane graft has a density of 0.865 to 0.880 g / cm ³ , a melt flow rate of 0.5 to 5 g / 10 minutes at a load of 190 ° C. × 2.16 kg, Shore A. It has a hardness of 55 to 70, a flexural modulus of 3 to 50 MPa, a melting point of 100 ° C. or higher, and
Claim 1 is characterized in that the (B) unmodified polyolefin has a melt flow rate of 0.5 to 5 g / 10 minutes under a load of 190 ° C. × 2.16 kg, a flexural modulus of 3 to 200 MPa, and a melting point of 65 ° C. or higher. The composition for an electric wire covering material according to any one of 6 to 6 . The polyolefin constituting the (A) silane graft polyolefin and the (B) unmodified polyolefin are selected from a homopolymer of ethylene and propylene, a copolymer of ethylene or propylene and α-olefin, and a polyolefin elastomer, respectively. The composition for an electric wire coating material according to any one of claims 1 to 7, wherein the composition is one kind or two or more kinds. The polyolefin constituting the (A) silane graft polyolefin and the (B) unmodified polyolefin are one or more selected from ultra-low density polyethylene, linear low density polyethylene, and low density polyethylene, respectively. The composition for an electric wire covering material according to claim 8, wherein the composition is characterized by the above. The invention according to any one of claims 1 to 9, wherein the (A) silane graft polyolefin has a gel fraction of 85% or more when mixed with the (E) crosslinking catalyst and crosslinked. The composition for an electric wire coating material according to the above. The modified polyolefin (C) is
An unmodified base polyolefin composed of one or more α-olefins, graft-polymerized with the polymerizable compound having the functional group, and
A copolymer of the polymerizable compound having a functional group with the polymerizable compound and a polymerizable olefin.
The composition for an electric wire covering material according to any one of claims 1 to 10, wherein the composition is one or more selected from the above. The (E) cross-linking catalyst may be one or more selected from a metal carboxylate selected from tin, zinc, iron, lead and cobalt, a titanic acid ester, an organic base, an inorganic acid and an organic acid. The composition for an electric wire covering material according to any one of claims 1 to 11, wherein the composition is characterized by being present. Further, with respect to a total of 100 parts by mass of the above (A), (B) and (C).
(F) Add 1 to 10 parts by mass of the antioxidant.
(G) 1 to 10 parts by mass of the metal inactivating agent,
(H) 1 to 10 parts by mass of lubricant,
The composition for an electric wire covering material according to any one of claims 1 to 12 , which comprises one kind or two or more kinds selected from the above . The (F) antioxidant is a hindered phenolic antioxidant, and is
The (G) metal inactivating agent is one or more selected from the copper inactivating agent and the chelating agent.
13. The thirteenth aspect of claim 13, wherein the (H) lubricant is one or more selected from hydrocarbons, fatty acids, higher alcohols, fatty acid amides, alkylene fatty acid amides, metal soaps, and ester-based lubricants. Composition for wire coating material. Further, with respect to a total of 100 parts by mass of the above (A), (B) and (C).
(I-1) 1 to 15 parts by mass of zinc oxide and 1 to 15 parts by mass of an imidazole compound.
(I-2) 1 to 15 parts by mass of zinc sulfate,
The composition for an electric wire covering material according to any one of claims 1 to 14 , which comprises any one of the above. An insulated wire having a wire covering material obtained by cross-linking the composition for a wire covering material according to any one of claims 1 to 15 . The insulated wire according to claim 16, wherein the gel content of the wire covering material is 50% or more. A wire harness comprising the insulated wire according to claim 16 or 17 .