Improvements in or relating to a method of preparing aqueous dispersions of an acid reacting synthetic resin

摘要

Synthetic resins prepared by Diels-Alder reaction between a terpene or diterpene and an ethylene-a : b -dicarboxylic acid are dispersed in an aqueous medium by heating under pressure at a temperature between 140 DEG and 200 DEG C. with alkali and water. There are specified: terpenes-natural resins having or forming on heating a conjugate double bond system, e.g. rosin, turpentine, a -terpinene, a -pinene, b -pinene, dipentene, limonene, terpinolene; acids-maleic, fumaric, itaconic, citraconic, and maleinanilic acids and their anhydrides; alkalis-caustic soda or potash. The preferred resin is a rosin-maleic reaction product. The resin is preferably heated in an autoclave at 160-170 DEG C. with an amount of alkali sufficient for 30-50 per cent neutralization of the resin. After being heated for 1/2 hour, the mix may be allowed to cool to 60-90 DEG C. before discharge from the autoclave. The quantities of ingredients used may be 50-80 per cent (by weight) resin, 4-14 per cent alkali and 6-46 per cent water. A concentrated dispersion so produced may be diluted with 15 to 60 times its weight of water at 10-65 DEG C. to give a dilute dispersion which may be used in the rosin-sizing of paper, in quantity such that the amount of condensate added is 5-40 per cent of the weight of rosin used. Examples illustrate the application of the process to rosin-maleic, rosin-citraconic, and terpinene-maleic condensates. According to the Specification as open to inspection under Sect. 91, it refers broadly to the use of Diels-Alder reaction products from substances having or forming upon heating a conjugate double bond system (of which it additionally specifies anthracene) and organic acids containing a CO : C : C grouping (of which it additionally specifies cinnamic acid). This subject-matter does not appear in the Specification as accepted.