Improvements in and relating to nitrogen containing polyester polymers

A nitrogen-containing polyester resin soluble in isopropanol-xylol mixtures and capable of curing when heated with an aldehydic material is the polycondensation product of (a) a mixture of dicarboxylic acids containing 80-91 mol. per cent of dicarboxylic acid having at least four carbon atoms in the skeletal chain directly connecting and including the two carboxyl groups and having no conjugated double bonds (i.e. no system including a pair of bonds whether between two carbon atoms or between a carbon atom and other atom separated by a single bond between carbon atoms) and correspondingly 9 to 20 mol. per cent of maleic, fumaric, itaconic or citraconic acid or an adduct of maleic anhydride with a conjugated diene (e.g. butadiene or cyclopentadiene) and (b) an N-aryldialkanolamine alone or in combination with a monoalkanolamine or an N-mono-hydrocarbon substituted monoalkanolamine or a glycol; the N-aryldialkanolamine being present in an amount to average at least one N-aryl group for each 100 atoms in the polymer chain connecting such N-aryl groups. Part of the alkanolamines may be replaced by diamines (e.g. 1 : 3-diamino butane or ethylene diamine). Specified reactants for (b) are: N-aryldialkanolamines-phenyl-, orthotolyl- and metatolyl-diethanolamine. Monoalkanolamines - monoethanolamine, monoisopropanolamine and 2-amino-1-butanol. N - monohydrocarbon - substituted monoalkenolamines - N - phenylmonoethanolamine, N - butylmonopropanolamine, N - benzylmonoethanolamine and N-cyclohexylmonoethanolamine. Glycols-polethylene glycol. The aldehydic curing agent may be paraformaldehyde, adipaldehyde, alpha-hydroxyadipaldehyde or glyoxal, a condensation product of an amino compound or a phenol and an aldehyde, or a condensation product of melamine, formaldehyde and butanol. The curing reaction may be accelerated by the addition of oxalic, phthalic, salicylic, lactic, maleic or citric acid. The polyesters are useful for impregnating porous paper in the production of sheet material for use as gaskets, backings for abrasive coated sheet material and particularly as backings for the production of pressuresensitive adhesive tape (see Group VIII). In examples, polyesters were made from (1) Phenyldiethanolamine, dimerised fatty acids, diglycolic acid and maleic anhydride; (2) phenyldiethanolamine, polyethylene glycol (M.W. 200), monoethanolamine, sebacic acid and maleic anhydride; (3) phenyldiethanolamine, monoethanolamine, sebacic acid, adipic acid and maleic anhydride