GB957409A - Synthetic waxes - Google Patents

Abstract

Synthetic waxes are prepared by reacting dicarboxylic acids (6-12C) with a molar excess of one or more aliphatic diamines (2-6C) by heating at an elevated temperature until evolution of water ceases, and condensing the polyamide product with one or more aliphatic monocarboxylic acids (11-25C) in an amount from 1/20 to 1/10 mole per mole of diamine used in the first condensation and less than sufficient to condense with all the terminal amine groups in the polyamide product by heating the reactants at a temperature higher than the first condensation temperature until a homogenous mass is obtained. Ethylene diamine, 1,2- and 1,3-diaminopropane and 1,6-diaminohexane, or mixtures thereof may be used, and adipic and sebacic acids are preferred acids. Mixtures of acids may be used and other dibasic acids such as succinic and phthalic acids may be included in the first stage. Lauric, oleic, palmitic, stearic or 12-hydroxystearic acids or mixtures thereof, and mixtures of long chain fatty acids derived from the hydrolysis of natural oils and fats such as linseed, castor, sunflower oils and tall oil, hardened castor oil or dehydrated castor oil fatty acids are examples of the monocarboxylic acids. The products may be used in a solvent, e.g. hot dimethylformamide, as coating compositions for the interior of steam condensers.ALSO:Synthetic waxes are prepared by reacting dicarboxylic acids (6-12C) with a molar excess, of one or more aliphatic diamines (2-6C) by heating at an elevated temperature until evolution of water ceases and condensing the polyamide product with one or more aliphatic monocarboxylic acids (11-25C) in an amount from 1/20 to 1/10 mole per mole of diamine used in the first condensation and less than sufficient to condense with all the terminal amine groups in the polyamide product, by heating the reactants at a temperature higher than the first condensation temperature until a homogenous mass is obtained. Ethylene diamine, 1,2- and 1,3- diaminopropane and 1,6-diamino hexane, or mixtures thereof may be used, and adipic and sebacic acids are the preferred acids. Mixtures of acids may be used and other dibasic acids such as succinic and phthalic may be included in the first stage. Lauric, oleic, palmitic, stearic, or 12-hydroxy stearic acids or mixtures thereof, and mixtures of long chain fatty acids derived from the hydrolysis of natural oils and fats such as linseed, castor, sunflower oils, and tall oil, hardened castor oil, or dehydrated castor oil fatty acids are examples of the monocarboxylic acids. The products may be used, in a solvent, e.g. hot dimethylformamide, as coating compositions for the interior of steam condensers.