GB1090593A - New polyesters - Google Patents

Abstract

A polyester is prepared by heating together a benzene o-dicarboxylic acid, a polyhydric alcohol and a monohydric alkanol, alkenol or cycloalkanol having at least 5 C atoms; the product is converted into a hydrophilic salt by treatment with ammonia or an amine; a part of the benzene-o-dicarboxylic acid may be replaced by one or more other polycarboxylic acids and/or one or more monocarboxylic acids, provided that at most 30% by weight of the carbonyl-contributing (i.e. acid) components are acids whose ethyl esters have alkaline dissociation constants in water at 25 DEG C. greater than 10-2 litres/mole/second. Acids of the category limited to 30 weight per cent include castor, dehydrated castor, coconut, cottonseed, train, soyabean, perilla and tall oil fatty acids, succinic, adipic, maleic, acrylic, isophthalic and trimellitic acids. Acids not so limited include, besides the o-benzene dicarboxylic acids, benzoic acid and aliphatic monocarboxylic acids in which the a carbon atom carries 2 or 3 alkyl groups, e.g. 2-methylnonanoic acid. Suitable polyols include ethylene, diethylene, polyethylene, propylene and polypropylene, butylene-1:3 and - 1:4 and pentylene 1:5 glycols and 2-methylpentane-2:4 diol; glycerol, hexane-1:2:6-triol, trimethylolpropane, trimethylolethane, pentaerythritol, dipentaerythritol and sorbitol. Suitable monohydric alcohols include amyl, cyclohexyl, octyl, decyl, lauryl and stearyl alcohols and " oxo " alcohols. These polyesters may be used in aqueous coating, impregnating, adhesive or textile treating compositions. The compositions may also comprise a curable aminoplast condensate, an organic water-miscible co-solvent and optionally pigments and flow agents, e.g. silicones, cellulose ethers, and wetting agents. Suitable aminoplasts are methylolated urea, ethyleneurea, uron, melamine, acetoguanamine or benzoguanamine and ethers thereof. In examples, phthalic anhydride is condensed with trimethylolpropane, or (in Examples 5 and 6) with hexane-1:2:6-triol, and isodecanol, and the product is further condensed with phthalic anhydride, or (in Example 6) with maleic anhydride, then treated with triethylamine and dissolved in water or water/ ethylene glycol monobutyl ether, the solution of Example 1 is mixed with methoxymethylmelamine (c. 4.5 methoxy groups per melamine residue) and rutile TiO2 to give a stoving varnish in which steel plates are dip-coated.ALSO:Coating compositions comprise polyesters prepared by condensing a benzene-o-dicarboxylic acid with a polyol and a monohydric alkanol, alkenol, or cycloalkanol having at least 5C atoms to give a polyester having free carboxyl groups which is then neutralized with ammonia or an amine. A part of the benzene-o-dicarboxylic acid may be replaced by one or more other polycarboxylic acids or monocarboxylic acids, provided that at most 30 wt. % of the acid components are acids whose ethyl esters have akaline dissociation constants in water greater than 10-2 litres/mole/second (see Division C3). In Example 7 steel plates are dip coated in a stoving lacquer containing 6 p.b.w. water, 1.5 p.b.w. ethylene glycol monobutyl ether, 2.5 p.b.w. rutile TiO2, 1 p.b.w. of polymethoxymethylmelamine and 4 p.b.w. of the triethylamine salt of a condensate of phthalic anhydride, trimethylolpropane and isodecanol.