Automobile insulated wire
An insulated wire for an automobile coated with an insulating material which is a fire retardant polypropylene-based resin composition, wherein the fire retardant polypropylene-based resin composition comprises a polypropylene-based resin and an inorganic fire retardant at a ratio of from 80 to 20% by weight and from 20 to 80% by weight, respectively, wherein the ratio Λ(=λ/λa) of the elongation percentage at a yield point λ of the fire retardant polypropylene-based resin in the resin composition to the elongation percentage at a tensile yield point λa of the polypropylene-based resin alone satisfies the following equation (1): Λ=1−α W (1) wherein α represents a number of 0.6 or less; and W is the weight fraction of the inorganic fire retardant.
1. An insulated wire for an automobile coated with an insulating material which is a fire retardant polypropylene-based resin composition,
wherein the fire retardant polypropylene-based resin composition comprises a polypropylene-based resin and an inorganic fire retardant at a ratio of from 80 to 20% by weight and from 20 to 80% by weight, respectively,
wherein the ratio Λ(=λ/λa) of the elongation percentage at a yield point λ of the polypropylene-based resin in the resin composition to the elongation percentage at a tensile yield point λa of the polypropylene-based resin alone satisfies the following equation (1):
Λ=1 −αW (1)
wherein α represents a number of 0.6 or less; and W is the weight fraction of the inorganic fire retardant, and
wherein the polypropylene-based resin comprises:
a component (a-1) which is a propylene-α-olefin copolymer containing a xylene-soluble content of from 40% by weight to 80% by weight polymerized by a multi-stage polymerization method, and has a ηXs/ηXis ratio of 2.5 or less in which the ηXs and the ηXis are the intrinsic viscosity of a xylene-soluble content (Xs) and the intrinsic viscosity of a xylene-insoluble content (Xis), respectively, each measured with tetralin at 135° C.
a component (a-2) of a propylene homopolymer and/or a propylene-α-olefin random copolymer, and
a component (a-3) of a propylene homopolymer and/or a propylene-α-olefin copolymer containing a carboxylic acid group or acid anhydride group in an amount of 0.5% by weight or more,
wherein the total content of the component (a-1) and the component (a-2) is from 50 to 90% by weight and the content of the component (a-3) is from 10 to 50% by weight.
2. The insulated wire for an automobile according to claim 1 , wherein the inorganic fire retardant is a metal oxide, metal hydroxide or metal carbonate having an average particle diameter of 20 μm or less.
3. The insulated wire for an automobile according to claim 1 , wherein the inorganic fire retardant is a magnesium hydroxide or aluminum hydroxide having an average particle diameter of 20 μm or less.
4. The insulated wire according to claim 1 , which has a low temperature durability of not higher than 40° C.