Pulsed voltage surges resistant enamelled wires

Abstract

A pulsed voltage surges resistant enamelled wire comprises a metal conductive wire and at least one shield layer outside the wire, the shield layer is provided by a coating composition comprising (a) a synthetic resin, (b) an organic solvent and (c) metal oxide particles, wherein the metal oxide particles comprise α-form Al 2 O 3 particles, γ-form Al 2 O 3 particles and transition metal oxide particles.

1 . A pulsed voltage surges resistant enamelled wire comprising a metal conductive wire and at least one coating layer outside the wire, wherein at least one of the coating layer(s) is a shield layer containing metal oxide particles and the metal oxide particles comprise α-form and γ-form Al 2 O 3  particles and transition metal oxide particles.  
     
     
         2 . The enamelled wire according to  claim 1 , wherein the shield layer is provided by a coating composition comprising (a) a synthetic resin, (b) an organic solvent and (c) metal oxide particles, wherein the metal oxide particles comprise α-form and γ-form Al 2 O 3  particles and transition metal oxide particles.  
     
     
         3 . The enamelled wire according to  claim 1 , wherein the transition metal oxide is selected from the group consisting of Cr 2 O 3 , TiO 2 , SiO 2 , Zr 2 O 3 , ZnO and Fe 2 O 3 .  
     
     
         4 . The enamelled wire according to  claim 3 , wherein the transition metal oxide is Cr 2 O 3 .  
     
     
         5 . The enamelled wire according to  claim 2 , wherein the coating composition comprises from 3 to 20 parts by weight of metal oxide particles per hundred parts by weight of the synthetic resin.  
     
     
         6 . The enamelled wire according to  claim 5 , wherein the coating composition comprises from 5 to 15 parts by weight of metal oxide particles per hundred parts by weight of the synthetic resin.  
     
     
         7 . The enamelled wire according to  claim 5 , wherein the coating composition comprises from 2 to 19 parts by weight of transition metal oxide particles per hundred parts by weight of the synthetic resin.  
     
     
         8 . The enamelled wire according to  claim 7 , wherein the coating composition comprises from 5 to 15 parts by weight of transition metal oxide particles per hundred parts by weight of the synthetic resin.  
     
     
         9 . The enamelled wire according to  claim 8 , wherein the coating composition comprises from 5 to 10 parts by weight of transition metal oxide particles per hundred parts by weight of the synthetic resin.  
     
     
         10 . The enamelled wire according to  claim 5 , wherein the ratio between the α-form Al 2 O 3  particles and the γ-form Al 2 O 3  particles is from 1:1 to 1:100.  
     
     
         11 . The enamelled wire according to  claim 5 , wherein the ratio between the α-form Al 2 O 3  particles and the γ-form Al 2 O 3  particles is from 1:5 to 1:50.  
     
     
         12 . The enamelled wire according to  claim 5 , wherein the ratio between the α-form Al 2 O 3  particles and the γ-form Al 2 O 3  particles is from 1:5 to 1:15.  
     
     
         13 . The enamelled wire according to  claim 1 , wherein the particle size of the metal oxide particles is from 0.01 to 5 microns.  
     
     
         14 . The enamelled wire according to  claim 2 , wherein the synthetic resin is selected from the group consisting of modified or unmodified polyacetal, polyurethane, polyester, polyesterimine, polyimine, polyamide, polysulfone, polyimide resins and mixtures thereof.  
     
     
         15 . The enamelled wire according to  claim 2 , wherein the organic solvent is selected from the group consisting of cresols, hydrocarbons, dimethyl phenol, toluene, xylene, ethyl benzene, N,N-dimethyl formamide, N-methylpyrrolidone, esters, ketones, and mixtures thereof.  
     
     
         16 . The enamelled wire according to  claim 2 , wherein the coating composition comprises, based on the total weight of the synthetic resin and the organic solvent, from 80 to 20 wt % synthetic resin and from 20 to 80 wt % organic solvent.  
     
     
         17 . The enamelled wire according to  claim 16 , wherein the coating composition comprises, based on the total weight of the synthetic resin and the organic solvent, from 75 to 25 wt % synthetic resin and from 25 to 75 wt % organic solvent.