Synthesis And Properties Of Acrylic Copolymer Composite Emulsions Modified By Waterborne Polyurethane

Recently,waterborne coatings have been widely researched and attended with the increased people's awareness on the environment pollution problem and the energy crisis.Acrylic copolymer latexes(PA) and waterborne polyurethane(PU) have been widely used as the film-forming materials of waterborne coatings,and both of them have their own characteristic advantages and disadvantages.Combination of PU with PA is expected to be an effective method to increase the properties of the resulting materials.Therefore,the studies on PU-modified PA copolymer latexes (PUA) have been chiefly studied in this work.In addition,PUA modified by epoxy resin(EP) which have different core-shell structures,are obtained by using a new epoxy functional monomer which contains double bonds.It is worthy said that,the core-shell structure which is PU in shell and PA in core have been scarcely reported before.In this paper,PA latexes are prepared by the method of "particle structure designing".The effects such as the amount of the functional monomer DAAM, co-monomer AN,the initiator APS,and the seed emulsion,the mass ratio of hard and soft monomer(MMA,St,BA),and the emulsifiers COPS-I and CO-436 on the properties of PA latexes and films are studied.Furthermore,the EP-modified PA emulsions are also investigated.The PA latexes with better integrative properties are obtained,when the feeding method of shell monomer is starved semi-continuous,the mass ratio of monomers MMA,St and BA is 18:16:14,the amount of seed emulsion is 10%-15%,the amount of APS is 0.5%-0.7%,the amount of AN is 12-16%,the amount of DAAM is 4%,COPS-I and CO-436 ratio is 4:1.Moreover,water resistance, toluene solvent resistance and mechanical properties of PA latexes are improved after using EP modification.In this paper,PUA composite emulsions are prepared by ab initio polymerization method.The effects such as the amount of DMPA and TMP,the molar ratio of NCO/OH and the mass ratio of PU and PA on the properties of PUA emulsions and films are studied.Furthermore,PU dispersions modified by nano-SiO2 are also investigated.The PUA composite emulsions with better integrative properties are obtained,when the amount of DMPA is 5%-6%and TMP is 2%-3%,the molar ratio of NCO/OH is 1.3-1.4,and the mass ratio of PU and PA is 65/35-50/50.Moreover,PU dispersions modified by nano-SiO2 show better integrative properties,but nano-SiO2 are severe agglomeration in the PU films.In this paper,PUA composite emulsions modified by EP with different core-shell structure are prepared by using a new EP functional monomer,which contains double bonds,through in-situ method.The results show that the hydrophobicity,toluene solvent resistance and mechanical properties of PUA emulsions and films are improved after using EP modification.