Synthesis And Properties Of Acrylic Emulsion Modified By Vinyl Tetra-coordinated Silicon And Waterborne Polyurethane

Acrylate emulsion has been applied to a variety of high-grade coating, because of its low VOC, low toxicity, use of safety and environment friendly, and its film has high glossiness and good mechanical property. The Acrylate emulsions modified by vinyl tetra-coordinated silicone and waterborne polyurethane which had advantages of environment friendly and low energy consumption were prepared. The performance of the emulsions and its films were studied:(1)The acrylate emulsion with core-shell structure had been successfully synthesized through seed emulsion polymerization, and its structure and properties had been studied. The result showed that the emulsion had the best comprehensive performance when the amount of BA,MMA,AA,AM were 40.50%,56.00%,2.30% and 1.20%, respectively, and the content of emulsifier and initiator were 1.40% and 0.45% of the total monomer.(2)The vinyl tetra-coordinated silicon with carbon-carbon double bond was prepared by the reaction of high activity penta-coordinated silicon potassium compound with allyl bromide. The yield was more than 98%. The acrylate emulsion with a double layer core-shell structure modified by vinyl tetra-coordinated silicon had been synthesized. Comparing with the unmodified emulsion, the mechanical and thermal properties of the films prepared by modified emulsion had been improved. The water absorption of the film decreased from 19.64% to 9.23%, and the initial thermal decomposition temperature(Td) of the film was 314.00℃, 10℃ higher than the unmodified one when the film containing 5% tetra-coordinated silicon.(3)The acrylate emulsions(PUA and DPUA) modified by hydroxyl terminated waterborne polyurethane and double bone terminated waterborne polyurethane had been synthesized and studied. The result showed that PUA had a multi-core core-shell structure. The flexibility of the films prepared by modified emulsion had been improved. When the ratio of PTMG1000/total polyether glycol was 0.6, R=2.9, the content of hard segment was 48%, the film of PUA showed the best performance that the water absorption was 16.48%, the Td was 277.16℃, the pencil hardness was 3 H, impact strength was 50 kg·cm. And the water absorption was 17.34%, the pencil hardness was 3 H, the Td was 268.62℃ when R=1.9 of the film prepared by DPUA.(4)The acrylate emulsion(SPUA) modified by both vinyl tetra-coordinated silicon and waterborne polyurethane had been synthesized,and its structure was tested by IR、SEM、TEM and its properties had been studied. The result showed that the emulsion had a core-shell structure. The impact strength, adhesion strength and flexibility of the film were better than the blank film. When film containing 4% tetra-coordinated silicon showed the best performance, the pencil hardness was 3 H, the water absorptions was 16.09%, and the Td was 280.11℃ which had a good heat resistance.(5)The copolymers(VTMS and VTSS) with good thermal stability were synthesized by tetra-coordinated silicon with methyl methacrylate and styrene respectively through free radical solution polymerization. The Td of VTMS and VTSS were 292.16℃ and 310.42℃. The Gel Permeation Chromatography showed that the molecular of VTMS and VTSS were 39472 and 647352. The VTMS dissolved in DMSO and the VTSS dissolved in acetone, indicating that both copolymers were linear structure.