Polymethyl acrylate was reacted with hydrazine hydrate to give polyacrylic hydrazide. Analysis showed that 84.5% of methyl ester groups in the polymer molecule was converted into acid hydrazide groups. The polyacrylic hydrazide was found to be soluble in water and hydrochloric acid solution, and to indicate the behavior of cationic polyelectrolyte in the solution.
Application of polyacrylic hydrazide to paper making was studied, and it was found that the hydrochloric acid solution of the polymer can be utilized as an excellent, size-fixing and strengthing agent of paper.
It is interesting that the remarkable effect was found on the sizing of ordinary paper as well as that used calcium carbonate as a filler. By the fixing action of polyacrylic hydrazide, sizing effect of petroleum resin on paper was improved, and especially the sizing effect estimated by ink-floating method was markedly elevated.
The best effect was obtained just when polyacrylic hydrazide was first dissolved in 0.1N hydrochloric acid, added 0.3% of it to pulp in beater, giving further addition of size followed by filler. The size-fixing effect was more than scores times of that of melamine-formaldehyde resin.
Strengthing effect of polyacrylic hydrazide on paper was also found to be several times of that of alpha starch.
Synthesis of polyacrylic hydrazide is comparatively ease, and degree of polymerization and hydrazide group content of the polymer can be controlled. Much application of polyacrylic hydrazide to paper making is expected in future.