GB704008A - Improvements in or relating to resinous compositions, particularly for insulating purposes - Google Patents

Abstract

A resinous composition particularly suitable for electrical insulation is prepared by mixing (A). 95-60 parts by weight of a polyesteramide with a softening temperature not above 90 DEG C. and prepared from (a) 3-4.5 mols. of at least one ethylenically unsaturated acid or anhydride; (b) 0.5-2.0 mols. of at least one saturated dicarboxylic acid or anhydride having at least 4 carbon atoms; (c) 1.5-4.7 mols. of an amino alcohol, at least 75 per cent. of which is monoethanolamine and/or monoisopropanolamine; (d) up to 0.6 mol. of ethylene diamine and/or propylene diamine and/or urea (the sum of the mols. of (c) and twice the mols. of (d) being 2.2-4.7); and (e) 1-2.4 mols. of at least one polyhydric alcohol, not more than 75 per cent. of which has more than 3-OH groups, with (B) 5-40 parts by weight of a complex resinous epoxide from a polyhydric phenol softening at 40 DEG -140 DEG C. The mixture of (A) and (B) is heated to form a copolymer having a softening temperature of 27 DEG -55 DEG C. for a 70 per cent. solution in cresol. Specified ingredients for the polyester-amide which may be prepared by the process claimed in Specification 665,309 are: (a) maleic acid, maleic anhydride, fumaric acid, citraconic acid, citraconic anhydride, aconitic acid, fumaric acid, 3, 6 - endomethylene-D -4-tetrahydrophthalic anhydride and dilinoleic acid, (b) adipic, succinic, azelaic, diglycolic and sebacic acids, (e) glycerol, ethylene glycol; diethylene glycol; pentaerythritol; 1, 1, 1-trimethylolpropane; 1, 4-butanediol; 1, 6-hexanediol, and paraffinic glycols with up to 8 carbon atoms in a chain. 0.05-0.5 mol. of an aliphatic unsaturated monocarboxylic acid having 16-18 carbon atoms, e.g. tung oil acids, linseed oil acids, ricinoleic, oleic, linoleic or linolenic acid may be included in the polyesteramide reaction mixture. Preferably COOH groups should not exceed OH and NH2 groups by more than 10 per cent. or OH and NH2 groups exceed COOH groups by more than 20 per cent. The resinous epoxide is prepared from 1 mol. of a dihydric phenol and 1-2 mols. of an epihalohydrin or dihalohydrin in presence of caustic alkali. Phenols specified are 4, 41-dihydroxydiphenyl-2, 21 propane; p.p1- dihydroxydiphenyl; resorcinol; hydroquinone; and condensation products of phenol or cresol with ketones. Halohydrins specified are epichlorobromo-or iodo-hydrin; glyceroldichlorhydrin and b -methyl glyceroldichlorhydrin. The resinous epoxide is preferably dissolved in cresylic acid, cresol or liquid phenols, added to the polyester-amide and reacted at a temperature above 100 DEG C. In preparing the copolymer small amounts of cellulose acetate, phenolic resin or ureaformaldedyde resin may be included in the reaction mixture. The phenolic resin may be a phenol-or cresol-formaldelyde or a tung oil modified phenol-formaldehyde one. The ureaformaldelyde resin is preferably butylated. The copolymeric product is preferably dissolved in a solvent, e.g. mixtures from metapara-cresol, petroleum hydrocarbons, monochlorobenzene, xylol, toluol and ethanol or isopropanol to yield a varnish suitable for coating metal conductors, or coils, or carbon or graphite members. A number of specific examples describe the manufacture of copolymers and their application as varnishes to copper wire. In one example a 20 per cent. solution in a phenol of cellulose acetate of given vicosity was mixed with the polyesteramide to give a mixture containing 5 per cent. cellulose acetate. The resinous peroxide was then added and the mixture reacted to form p the copolymer. Conductors coated with the compositions of the invention may be further coated with organopolysiloxanes. The products are also useful for coating metal sheets, e.g. for food containing or for protective and decorative coatings on metal, ceramics, glass, plastics, fabric or other materials.