| abstract |
An improvement in a process for coating a substrate by a powder coating process wherein a polyester powder is applied to said substrate which improvement comprises using as the polyester powder a partially crystalline powder of a polyester condensation product of an acid component comprising an acid or ester of at least terephthalic acid and a diol component at least 50 molar percent of which is 1,4-butanediol; a polyester coating powder which is a partially crystalline polyester of an acid component at least part of which is an acid or ester of terephthalic acid and a diol component at least 50 molar percent of which is 1,4-butanediol, said powder having a glass transition temperature between -20 DEG and +50 DEG C., measured as the attenuation maximum in accordance with Deutsche Industrie Norm 53,445 a reduced nred viscosity of at least 0.6, measured in a 1 weight percent solution of a mixture of 60 parts by weight phenol and 40 parts by weight phenol and 40 parts by weight 1,1,2,2-tetrachloroethane at 25 DEG C. and a melting maximum, determined by differential thermoanalysis, of about 150 DEG to 200 DEG C. |