| 摘要 |
<p>A modified polyester for use in insulating varnishes is obtained by reacting a saturated aliphatic polyol with an aromatic dicarboxylic acid and a mono- or di-unsaturated aliphatic monocarboxylic acid having 15-20 C atoms in the molecule, then reacting the product with a dicyclopentadiene polymer of molecular weight 600-1500; there are required 0.8-1.4 mols. of polyol per mol. of acids, and 0.8 to 1.2 mols. of aromatic acid per mol. of unsaturated acid, polymer are used per mol. of polyol used. Suitable polyols are glycerol, trimethylolethane, trimethylol propane, ethylene glycol, diglycol neopentyl glycol, and 1:4-butanediol. Suitable aromatic acids are o, m, and p phthalic acids, and unsaturated acids are oleic, linoleic and elaidic acids, or mixtures thereof, e.g. tall oil acids. The dicyclopentadiene polymer may be obtained by polymerizing a petroleum fraction boiling at 100-130 DEG C. and containing as major polymerizable components, cyclopentadiene, dicyclopentadiene, styrene, cyclohexadiene and methyl derivatives thereof. It may be replaced up to 20 mol. per cent by coumarone-indene polymers. A varnish is obtained by dissolving the modified polyester in a high-boiling aromatic petroleum hydrocarbon. A 20-40 wt. per cent solution in an aromatic petroleum fraction having a flash point of 200-250 DEG F. a distillation range 400-700 DEG F. and at least 85 mol. per cent aromatic content is preferred. In examples, an equimolar mixture of glycerol and trimethylolpropane, isophthalic acid and tall oil fatty acids are used in the process of the invention.ALSO:An insulating enamel composition may be applied to wire, by dip coating or die coating, and may also be applied over paper or glass fibre tape to give insulating wrappings. The composition comprises a polyester which is the reaction product of an aromatic dicarboxylic acid, a mono- or diunsaturated aliphatic monocanboxylic acid having 15 - 20 C atoms in the molecule, and a polyol or polyols, modified with a polycyclopentadiene polymer of molecular weight of 600 - 1500 (see Division C3), and dissolved in a high boiling aromatic petroleum hydrocarbon solvent.</p> |
