Synthesis And Preparation Of The Organosilicon-acrylate Emulsion With Core-shell Structure

Polyacrylate emulsion has been widely applied in coatings industry due to its excellent propenty of film forming, strength and adhesion etc.But it has some disadvantages such as poor water-resistance, poor film-forming in low temperature, becoming pastiness in high temperature, polluting environment with emulsifier and so on.Polydimethylsiloxane could resist low or high temperature and water.Emulision polymerization is safe in coatings industry and unpollute environment.So in this paper ,the organosilicon modified acrylate emulsions with a core-shell structure were studied. The results showed that the emulsion had lower viscosity, good storage stability and the film had excellent comprehensive performance, which could be used as coatings of degradable snack box.The two polydimethylsiloxanes were synthesized by using dimethyldiethoxysilane (Ld-10) monomer and octamehtylcyclotetrasilozane (D4) monomer under the condition of hydrochoric acid as catalyst. The results stability and particle size showed that the polydimethylsiloxane had excellent performance on polymerization, by researching polymerization velocity.The conversion of monomer abut 65%, particles were uniform in size while polydimethylsiloxane was synthesized by using D4 in temperature 80±1℃and pH value 1,2,3 .On the basis, organosilicon modified acrylate emulsions with a core-shell structure was synthesized. The effects of the reaction conditions on emulsion and film performance were determined:the organosilicon modified acrylate emulsions in D4 react pH value 3 and the monomer copolymerize on 6 hour had good performance;the mass ratio of acrylate monomer MMA/BA 1/1;the amount of core monomer 20%;the amonunt of crosslinking agent (NQ-71)7% ;the amonunt of initiator (APS) 0.7% by continuous feeding method; the amonunt of emulsifier 4%,SDBS/OP-10 3/2; the feeding method of shell monomer was continuous (time 1.5 hour);the amonunt of AA 0.5g;stirring speed 250rpm.Orthogonal experiments determined the reaction conditions on which the film with good water-resistance: the amount of core monomer 20%; the amonunt of crosslinking agent 7%;the amonunt of emulsifier 4%; MMA/BA 2/3(mass ratio).The emulsion could form transparent and obtained film.Its hydroscopicity 2.24%, at the room temprature slightly change after 20 mins in 80℃water,not fall off over 60 mins; solid contents...