Preparation And Properties Of Self-crosslinking Water-based Polyacrylate Dispersions

Acrylic acid resin is mainly acrylic monomer as the main monomer,the polymer obtained through polymerization reaction,generally used in coatings will have good weather resistance,and can play a decorative role.In recent years,with the continuous improvement of environmental protection requirements of the whole society,so that the emission of organic volatiles(VOC)has been restricted in various countries,which also led to the rise of water-based resin,and therefore the water-based acrylic resin is extremely important.Metal and its components exposed to the air for a long time is easy to be corroded,which will lead to economic losses,and over time will have a negative impact on the development of the national economy,and the most simple and effective way to protect the metal components is to coat the metal surface with coating.Although acrylic resin coatings have good metal protection performance,there are still some shortcomings such as poor film forming property,low hardness and insufficient corrosion resistance.Therefore,it is necessary to modify acrylic resin appropriately to prepare acrylic resin coatings with better performance.In this paper,acrylic resin is modified by introducing self-crosslinking monomer into the chain of polyacrylate molecules,and then the prepared resin dispersion was used as the base material,added an appropriate content of water-based additives to prepare the paint film and tested its performance.The main research contents were as follows:(1)With methyl methacrylate(MMA),butyl acrylate(BA),acrylic acid(AA),ethyl methacrylate acetyl acetoxyl group(AAEM)as the monomer,was prepared by phase inversion of solution polymerization before self-crosslinking acrylate dispersions,and used 1,6-adipate hydrazide as crosslinking agent preparation for self-crosslinking polyacrylate coating.The study of polyacrylate dispersion and its curing film showed that with the increase of AAEM content,the particle size of the dispersion increased and the contact angle of the film to water increased.With the increase of neutralization degree,the particle size of the dispersion decreased and the viscosity increased,and the contact angle of the film to water decreased.When AAEM content was 5.0～7.5 wt%,the glass transition temperature(T_g)of copolymer was45℃,neutralization degree was 90%,curing agent content was 150%,curing film had good performance.The chemical structures of the crosslinked monomer,curing agent,resin and curing film were characterized by high performance liquid chromatography and transmission infrared spectroscopy.It was proved that the self-crosslinked monomer was successfully grafted to the polyacrylate molecular chain segment and the curing reaction was carried out successfully.DSC analysis showed that when the content of AAEM was 5.0 wt%,T_g of the cured film was the highest,which reached 56.89℃,that was,the crosslinking degree of the film was the highest;TGA analysis showed that when the amount of AAEM was 5.0 wt%,the extrapolated initial temperature of the cured film was the highest,reaching 347.5℃,which indicated that the film had the best thermal stability.When the content of AAEM was 5.0～7.5 wt%,the T_gof copolymer was 45℃,neutralization degree was 90%,the content of ADH was 150%,the gel fraction of cured film was achieved 90%,curing film pencil hardness of H,adhesion for level 1,bending performance of 3 mm,resistance to impact of 50 kg·cm,resistance to water reached 72 h,had a good performance.(2)Through the first self-crosslinkable monomer in solution polymerization of ethyl methacrylate acetyl acetoxyl group AAEM to the polyacrylate molecular chain,was obtained by phase inversion method preparation of water dispersible again since the crosslinked polyacrylate,dispersions under the condition of high temperature baking could happen since the crosslinking,under the condition of 180℃when the curing time of 1h get coating gel fraction of about 71%.The study of polyacrylate dispersion and its curing film showed that with the increase of the content of AA,the particle size of the dispersion decreased while the viscosity increased,and the contact angle of the film to water decreased.With the increase of the content of AAEM,the particle size of the dispersion increased and the contact angle of the film to water increased.When the content of AA was 3.5 wt%,the content of AAEM was 5.0wt%,the T_g of copolymer was 45℃,and curing condition was 180℃receiving 1 h,the polyacrylate exhibited good film properties.The chemical structures of the crosslinked monomer,curing agent,resin and curing film were characterized by high performance liquid chromatography and transmission infrared spectroscopy.It was proved that the self-crosslinked monomer was successfully grafted to the polyacrylate molecular chain segment and the curing reaction was carried out successfully.DSC analysis showed that when the amount of AAEM was 5.0 wt%,the T_g of the cured film was the highest,which reached 60.53℃,that was,the crosslinking degree of the film was the highest;TGA analysis showed that when the amount of AAEM was 5.0 wt%,the extrapolated initial temperature of curing film was the highest,which reached 360.2℃,that was,the film had the best thermal stability.When the content of AA was3.5 wt%,the content of AAEM was 5.0 wt%,the T_g of copolymer was 45℃,the curing conditions of 180℃baking 1 h,the gel fraction of cured film was achieved 72.3%,curing film pencil hardness of 2 H,adhesion for level 1,bending performance of 3 mm,resistance to impact of 50 kg·cm,resistance to water reached 168 h,had a good performance.