Preparation Of Waterborne Polyurethane Containing Sulfonate Group And Polyurethane/polyacrylate Latex

How to combine the performances of waterborne polyurethane (WPU)and polyacrylate (PA) latex, to reduce the cost of pure polyurethane withoutreducing intrinsic properties or performance of polyurethane or to improveadhesion strength of polyacrylate with a high molecular weight, has been ahot topic of research all over the world.In this paper, PU/PA shell-core latexes with high ratio polyacrylate, highvinyl unsaturated carboxylic acid monomer introducing amount and excellentstability were prepared through seed emulsion polymerization using WPUcontaining sulfonated group as seed. While, the ratio of polyacrylate and theintroducing amount of vinyl unsaturated carboxylic acid monomer inconventional PU/PA shell-core latexes were much lower than above method.All the results can be showed as follows.Firstly, several sulfonated polyols were prepared by condensationpolymerizating5-sulfoiso phthalic acid mono sodium salt,2-sodium-1,4-butanediol, sulfonated maleic anhydride, which used as self-emulsifying units,and adipic acid respectively. The effects of reaction time during low temperature step and high temperature step on acid value and hydroxyl valuewere investigated in detail. The resulted product have a acid value under1mgKOH/g and hydroxyl value of79.55mgKOH/g and can be synthesizedwhen the reaction time of low temperature was1.0h, the reaction time of hightemperature was1.5h.Secondly, waterborne polyurethanes containing sulfonated group wereprepared through condensation polymerizing the above sulfonated polyol withIPDI. The effects of R value and theoretical non-volatile on the particle size ofWPU were studied. The results showed that the particle size increased withincreasing R value and an increasing theoretical non-volatile. The resultedWPU with an average particle size of28nm and non-volatile at25%wasgotten.Thirdly, the novel PUA latexes were synthesized through seed emulsionpolymerization by adding acrylates into above WPU. The effects of mass ratioof PA to PU on particle size, non-volatile of PUA latexes, and conversion ofacrylates as well as the effect of amount of AA on the stability of PUA latexeswere also researched. The results showed that particle size, non-volatile andthe conversion were increased with increasing PA/PU ratio. PUA latexes withexcellent stability can be manufactured more easily than traditional methodswhen the AA is5%. The particle shape and structure of PUA wascharacterized by transmission electron microscopy. The result showed that thePUA particle size was bigger than PU seed, and core-shell structure observed were observed easily.