Electric wire coating material composition, insulated electric wire, and wire harness

Abstract

A flame-retardant electric wire coating material composition that can improve heat resistance without using electron beam cross-linking, has no risk of reducing the mechanical characteristics and chemical resistance due to no metal hydroxides being added thereto as flame retardants, and can suppress the formation of die lip build-up and the like during manufacturing to achieve favorable productivity, and an insulated electric wire and a wire harness. The electric wire coating material composition may include:a silane-grafted polyolefin (A);an unmodified polyolefin (B);a modified polyolefin (C);a bromine-based flame retardant and antimony trioxide (D);a cross-linking catalyst batch (E);zinc oxide and an imidazole-based compound modified with a mercapto group, or zinc sulfide (F);an antioxidant, a metal deactivator, and a lubricant (G);silicone oil (H); andno metal hydroxides.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This application claims the priority of Japanese patent application JP2015-061294 filed on Mar. 24, 2015, the entire contents of which are incorporated herein.TECHNICAL FIELD[0002]The present invention relates to an electric wire coating material composition, an insulated wire, and a wire harness, and more specifically to an electric wire coating material composition that is preferable for a coating material for an insulated electric wire, such as a wire harness for an automobile, to be used at a position where high heat resistance is required, and an insulated electric wire and a wire harness.BACKGROUND ART[0003]In recent years, as a result of widespread use of hybrid cars and the like, electric wires and connectors, which are automobile parts, are required to have high voltage resistance and high heat resistance. Conventionally, electric wires coated with a cross-linked vinyl chloride resin or electric wires coated with a cross-linked p...

AI Technical Summary

Benefits of technology

[0005]However, it is necessary to add a filler serving as a flame retardant in order to impart flame retardance, which is a main essential characteristic of electric wires for automobiles. When inorganic flame retardants such as metal hydroxides are used, there is a risk that the flame retardants will be blended in a large amount, thus causing a decrease in mechanical characteristics. To address this, halogen-based organic flame retardants that have a higher flame retarding effect than the inorganic flame retardants have can be used to reduce the blend amount.

[0011]The present design was achieved in order to provide a flame-retardant electric wire coating material composition that can improve heat resistance without using electron beam cross-linking, has no risk of reducing the mechanical characteristics and chemical resistance due to no metal hydroxides being added thereto as flame retardants, and can suppress the formation of die lip build-up and the like during manufacturing to achieve favorable productivity, and an insulated electric wire and a wire harness.

[0045]The present design uses an electric wire coating material composition containing the above components (A) to (H) and no metal hydroxides, and thus can provide a flame-retardant electric wire coating material composition that can improve heat resistance without using electron beam cross-linking, has no risk of reducing the mechanical characteristics and chemical resistance due to no metal hydroxides being added thereto as flame retardants, and can suppress the formation of die lip build-up and the like during manufacturing to achieve favorable productivity, and an insulated electric wire and a wire harness.

Problems solved by technology

However, there is a problem in that an expensive electron beam cross-linking apparatus or the like is required to perform electron beam cross-linking, and equipment cost increases, resulting in increased product cost.

When inorganic flame retardants such as metal hydroxides are used, there is a risk that the flame retardants will be blended in a large amount, thus causing a decrease in mechanical characteristics.

However, when the halogen-based organic flame retardants are used, a problem arises in that a gelation rate, which is an index of the degree of cross-linking, and wear resistance are likely to decrease.

In materials for silane cross-linking, which is also known as water cross-linking, there is a concern that cross-linking is promoted by moisture in air during heat molding, resulting in the generation of abnormal substances, and therefore it is necessary to suppress the heating step as much as possible.

However, the formation of this masterbatch causes a problem in that the degree of cross-linking of the coating material decreases because the non-silane resin serving as a non-cross-linking component is contained therein, thus making it difficult to satisfy the standards on heat resistance and the like of automobiles.

Furthermore, the formation of this masterbatch also causes a problem in that a material containing a large amount of powder substances such as halogen-based organic flame retardants needs to be processed, and die lip build-up and the like are likely to be formed during the formation of an electric wire coating material through extrusion molding of an electric wire coating material composition, resulting in a decrease in the productivity of coated electric wires.

However, an increase in the cross-linking density of the silane resin causes a problem in that excessively cross-linked abnormal substances are likely to be generated during molding, and also cause die lip build-up, resulting in a decrease in the productivity.

Therefore, the electric wires increase in weight and become hard, thus causing a problem in that the workability for assembly of a wire harness and the like decreases.

When the flexibility of the electric wires is improved to address this, a problem arises in that an affinity to an organic solvent such as gasoline or light oil to be used in automobiles increases, and thus the electric wires are likely to swell.