The novel diol chain-extender trimethylol propane monolaurate (TMPLA) was synthesized to prepare novel polyurethane aqueous dispersions (n-PUD)
which was used as a coalescent to assist the film forming of high Tg polyacrylate emulsion. Effects of NCO/OH molar ratio
soft/hard segment contents and molar ratio of TMPLA/BDO on assistant-film-forming performance of n-PUD were studied. It was found that the assistant-film-forming ability of PUD was increased with decreasing of NCO/OH molar ratio and hard segment proportions. PUDs modified with TMPLA displayed good assistant-film-forming ability. The optimized conditions to prepare assistant-film-forming n-PUD were as follows: molar ratios of TMPLA/BDO and NCO/OH were 4/2 and 1.3
respectively
mass ratio of soft/hard segment was 55/45
and then the blended latex with m(PUD)/m(PA) 25/75 can form a continuous transparent film at 5℃ without coalescent with a VOC content as low as 30 g·L-1.