Multilayer insulated wire and a manufacturing method therefor

A bondable multilayer insulated wire comprising:

• (i) a conductor;
• (ii) three or more insulating layers covering the surface of the conductor;
• and
• (iii) a bondable layer covering the outermost one of the insulating layers,
• each of first and second insulating layers, as counted from the conductor side, being selected from the group consisting of
• (a) an extrusion-coating layer of an intimate resin mixture compounded so that an ethylene-based copolymer, having a carboxylic acid or a metal salt of the carboxylic acid on a side chain thereof, accounts for 5 to 40 parts by weight to 100 parts by weight of a thermoplastic straight-chain polyester resin formed by combining an aliphatic alcoholic constituent and an acid constituent,
• (b) an extrusion-coating layer comprising a thermoplastic straight-chain polyester resin, the whole or a part of which is formed by combining a cycloaliphatic alcoholic constituent and an acid constituent, and
• (c) an extrusion-coating layer of an intimate resin mixture compounded so that an ethylene-based copolymer, having a carboxylic acid or a metal salt of the carboxylic acid on the side chain thereof, accounts for 50 parts or less by weight to 100 parts by weight of a thermoplastic straight-chain polyester resin, the whole or a part of the thermoplastic straight chain polyester resin is formed by combining a cycloaliphatic alcoholic constituent and an acid constituent,
• a third insulating layer being an extrusion-coating layer of a thermoplastic polyamide resin or an intimate resin mixture comprising the thermoplastic polyamide resin, and
• the bondable layer being an extrusion-coating layer of an copolymerized-polyamide resin.

In a transformer including a wire element, wherein the improvement comprises the wire element being multilayer insulated wire comprising;

• (i) a conductor;
• and
• (ii) three or more insulating layers covering the conductor,
• each of first and second insulating layers, is counted from the conductor side, being selected from the group consisting of
• (a) an extrusion-coating layer of an intimate resin mixture compounded so that an ethylene-based copolymer, having a carboxylic acid or a metal salt of the carboxylic acid on a side chain thereof, accounts for 5 to 40 parts by weight to 100 parts by weight of a thermoplastic straight-chain polyester resin formed by combining an aliphatic alcoholic constituent and an acid constituent,
• (b) an extrusion-coating layer comprising a thermoplastic straight-chain polyester resin, the whole or a part of which is formed by combining a cycloaliphatic alcoholic constituent and an acid constituent, and
• (c) an extrusion-coating layer of an intimate resin mixture compounded so that an ethylene-based copolymer, having a carboxylic acid or a metal salt of the carboxylic acid on the side chain thereof, accounts for 50 parts or less by weight to 100 parts by weight of thermoplastic straight-chain polyester resin, the whole or a part of the thermoplastic straight-chain polyester resin is formed by combining a cycloaliphatic alcoholic constituent and an acid constituent, and
• a third insulating layer being an extrusion coating layer of a thermoplastic polyamide resin or an intimate resin mixture comprising of the thermoplastic polyamide resin.

In a transformer including a wire element, wherein the improvement comprises the wire element being the bondable multilayer insulated wire comprising

• (i) a conductor;
• (ii) three or more insulating layers covering the surface of the conductor;
• and
• (iii) a bondable layer covering the outermost one of the insulating layers,
• each of first and second insulating layers, as counted from the conductor side, being selected from the group consisting of
• (a) an extrusion-coating layer of an intimate resin mixture compounded so that an ethylene-based copolymer, having a carboxylic acid or a metal salt of the carboxylic acid on a side chain thereof, accounts for 5 to 40 parts by weight to 100 parts by weight of a thermoplastic straight-chain polyester resin formed by combining an aliphatic alcoholic constituent and an acid constituent,
• (b) an extrusion-coating layer comprising a thermoplastic straight-chain polyester resin, the whole or part of which is formed by combining a cycloaliphatic alcoholic constituent and an acid constituent, and
• (c) an extrusion-coating layer of an intimate resin mixture compounded so that an ethylene-based copolymer, having a carboxylic acid or a metal salt of the carboxylic acid on the side chain thereof, accounts for 50 parts or less by weight to 100 parts by weight of the thermoplastic straight-chain polyester resin, the whole or a part of the thermoplastic straight-chain polyester resin is formed by combining a cycloaliphatic alcoholic constituent and an acid constituent,
• a third insulating layer being an extrusion-coating layer of a thermoplastic polyamide resin or an intimate resin mixture comprising the thermoplastic polyamide resin, and
• the bondable layer being an extrusion-coating layer of an copolymerized-polyamide resin.