Preparation of aqueous thermosetting electrical insulating varnishes

US4439579A · kind A · utility

Assignee

• BASF SE

Inventors

• Udo Reiter · Telgte, DE
• Hans-Uwe Schenck · Monsheim, DE
• Helmut Lehmann · Bad Nauheim, DE
• Ferdinand Hansch · Wedel, DE

Key dates

• Filing date: Apr 29, 1982
• Grant date: Mar 27, 1984
• Expiry date: Apr 29, 2002

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10T428/31721
• WIPO field: Electrical machinery, apparatus, energy
• WIPO sector: Electrical engineering

Abstract

Aqueous thermosetting electrical insulating varnishes are prepared by a process wherein hydroxyl-containing polyester-imides which have kinematic viscosities of from 16 to 30 mm.sup.2 .multidot. s.sup.-1 and acid numbers of <10, and which have been obtained by condensing aromatic tricarboxylic acid monoanhydrides, aromatic dicarboxylic acids or their esterifiable or transesterifiable derivatives, diamines, diols, and triols containing an isocyanurate ring, are treated, at from 80.degree. to 130.degree. C., in the presence or absence of up to 5% by weight, based on polyester-imide, of an organic solvent, with from 5 to 15% by weight, based on polyester-imide, of ammonia in the form of an aqueous solution, thereby producing aminolysis and hydrolysis so that a neutral or slightly acidic solution results, which is diluted to a viscosity of from 100 to 10,000 mPa.s by adding demineralized water, from 0.1 to 5% by weight, based on polyester-imide, of a water-soluble curing catalyst being added, if desired, after the treatment with ammonia. The electrical insulating varnishes are used as wire enamels or as impregnating varnishes.