Synthesis And Application Research Of Styrene-acrylate Emulsion With Excellent Freezing And Thawing Stability

High PVC interior wall coating is an important part of architectural coatings. At present,in order to improve the poor freeze-thaw stability of coatings, conventional method is to addantifreeze. However, the addition of antifreeze and other volatile organic compounds (VOC)have a great threat to human health. Consequently, the use of antifreeze will be restricted oreven banned, low or zero VOC and high PVC interior wall coating without any antifreezeswill be widely concerned and studied with increasingly strengthen environmental awarenessand strict environmental regulations.Emulsions, as the main component of high PVC interior wall coating, have directlyinfluence on the comprehensive properties of coating. It is well known that styrene-acrylicemulsions have been widely used for the low price, excellent chemical and physicalproperties.In this paper, styrene-acrylice emulsions with excellent freeze-thaw stability werestudied and synthesized by semi continuous seed emulsion polymerization. The factors thatinfluence the freeze-thaw stability of styrene-acrylic emulsions were investigatedsystematically. The results showed that the type and content of emulsifiers, polymerizationmethod, polymer glass transition temperature(Tg), initiator content and buffer content hadgreat influence on freeze-thaw stability of styrene-acrylic emulsions. Styrene-acrylicemulsions with excellent freeze-thaw stability could be obtained under the optimizedconditions as follows: the compound emulsifiers were DNS-628/AMPS-Na=1/1(mass ratio)and the content was2.5%, the Tg was15~20℃, the content of seed monomers was10%, theinitiator content was0.55%, the buffer content was0.3%.Modification researche had been taken to improve the chemical stability ofstyrene-acrylic emulsions, the adhesion and mechanical properties of latex film. The resultsshowed that acrylamide and its derivatives could improve the chemical stability ofstyrene-acrylic emulsions, crosslinking monomer with carbamido(V-50M) and silanecoupling agent(C2287) could improve the adhesion and mechanical properties of emulsionfilm. Modified styrene-acrylic emulsions with excellent comprehensive properties could beobtained under the optimized conditions as follows: the MAM content was1～1.5%, theV-50M content was1.5%, and the C2287content was1～1.5%.Modified styrene-acrylic emulsions were applied to formulate the high PVC interior wallcoatings, which without any antifreezes. The effects of dispersing agents, wetting agents, thickening agents and coalescing agents on freeze-thaw stability and other properties ofcoatings were disscussed systematically. The results showed that the interior wall coatingswith high PVC of80～85%was obtained, possessing excellent freeze-thaw stability and otherproperties. Such as low price, VOC content was4g/L, scrub resistance number was900～1127times. This will fill the domestic blank in low-end zero or low VOC interior wallcoatings, generate huge economic benefits.