Synthesis And Applicant Of Self-stratifying Epoxy Acrylate Composite Emulsion

With the development of economic and technology,all kinds of industries are developing rapidly.Nowadays society,an increasing number of people pay attention to environment and healthy related problems.Coating industry is associated with people’s life,so effective and environment-friendly coating has become the current trend of development of coating industry.In order to provide good anticorrosive effect,waterborne anticorrosion coating often needs coating multilayer films for many times,and have single function.And composite coating may have defects,like poor stability,poor constructability,et al.The first part of this paper prepared water epoxy resin emulsion by phase inversion technique,and synthesized epoxy/acrylate composite core/shell emulsion with epoxy as core and acrylate as shell by semi-continuous seed emulsion polymerization.In the second part,combined with epoxy curing agent,such composite emulsion can form self-stratified film while the surface is mainly acrylate and the bottom is mainly epoxy.Details are listed as follows:(1)Semi-continuous seed emulsion polymerization was used to synthesize epoxy/acrylate composite core/shell emulsion with epoxy as core and acrylate as shell.According to the attenuated total reflection infrared analysis,composite system has the epoxy content.According to transmission electron microscope analysis,dry emulsion particle presents irregular core/shell structure.When reactive emulsifiers’ content was 7%,the mass ratio of nonionic and ionic emulsifiers was 2:1,KPS’s content was 1.5%,stabilizers’ content was 0.36%,epoxy’s content was 40% and MAA’s content was 7%,the best emulsion could be prepared,whose conversion rate could reach 97%,gel fraction was less than 1%,the average particle size was about 200 nm,and had a good storage stability over 180 days.(2)Combined with epoxy curing agent,the composite emulsion formed a film.The influence of stabilizer,MAA and curing agent on film’s properties were studied.The influence of curing agent and film’s thickness on film’s self-stratification were also studied.Composite emulsion with MAA was 7% and stabilizer was 0.36% combined with low reactive curing agent,whose content was 12.50%,film had good properties,of which adhesion level was 1,hardness was 2H,water absorption was 4.44%,resistance to salt solution was up to 192 hours,resistance to neutral salt spray was up to 240 hours.Infrared analysis and scanning electron microscope suggested that when curing agent’s content was 12.50%,film’s self-stratification was obvious;when curing agent’s content was 18.75%,epoxy and acrylate were evenly distributed,so the film’s mechanical properties were better,of which adhesion level was 0 and hardness was 3H;Film’s thickness has effects on film’s stratification.When the film’s thickness was over 180μm,film’s self-stratification was inhibited to some degree.