| Because of the excellent weatherability and outdoor aging resistance,good color and gloss retention,excellent transparency,relatively abundant monomer resources and the ability of overcoming the shortcomings of epoxy when applied to be the undercoat,Cationic acrylic resin cathode electrophoretic coating can be expanded to decorative workpiece.Cationic acrylic resin itself has the disadvantages of poor pollution resistance,water resistance,heat and humidity resistance,corrosion resistance and pollution resistance when used as the base material of electrophoresis coating.Therefore,the basic research and application of modified cationic acrylic resin cathodic electrophoresis coatings are of great theoretical and commercial significance for the industrial application in the future.In this paper,based on the formula design theory of the synthesis of cationic acrylic resin.Free radical polymerization reaction was adopted,and dimethyl amino ethyl methacrylate(DMAEMA),hydroxyl ethyl methacrylate(HEMA),methyl methacrylate(MAA),butyl acrylate(BA),isobornyl methacrylate(IBOMA)were selected as the acrylic monomers,and then neutralized with glacial acetic acid to generate salt and a series of cationic acrylic resin(PA)were prepared.The best synthetic formula and technological conditions were determined based on the researches of resin water solubility and electrophoresis coating solvent stability,combining with the performance of electrophoresis coating.The cationic acrylic resin with a 70% solid content was synthesized when the dosage of azo diisobutyl cyanogen(AIBN)initiator was 2wt%,the reaction temperature was 85℃,the ratio of soft monomer and hard monomer(mass ratio)was 3:5,DMAEMA content was 13wt%,HEMA content was 15wt%,IBMA content was 6wt%,glacial acetic acid was chosen as the neutralizing agent and the neutralization degree was 70%.Secondly,the fully sealed HDI trimer was selected as the curing agent to determine the curing ratio of n(-NCO): n(-OH)was 1.2:1 to make the cathodic electrophoresis coating.No obvious changes were found of the electrophoresis coating solution after being stored at room temperature for more than 6 months,and there was no phase separation when centrifugated at 3500r/min for 20 min.Properties of electrophoresis coating: adhesion grade 0;Pencil hardness 3H;Impact resistance: 50kg·cm.On the basis of cationic acrylic resin binders,hexafluorobutyl methacrylate and Methacryllsobutyl POSS(MAPOSS)were selected as fluoride acrylic monomers and functional monomer containing silicon,respectively to synthesize cationic fluoride acrylic resin(FPA)and MAPOSS/fluorinated acrylate synergistically modified cationic acrylic resin(MFPA)by free radical solution polymerization.Judging from the FTIR spectrum,fluorine groups and POSS groups on the surface were introduced into PA.The effects of different amounts of fluorinated acrylate on the water solubility and coating properties of FPA resin were investigated,and the amount of fluorinated acrylate monomer was determined to be 9wt%.For the FPA formula,MAPOSS was added to modify the PA through late stage drip method,and the influence of different amounts of MAPOSS on the stability and coating properties of electrophoresis paint was investigated.The results showed that the water contact angle and diiodomethane contact angle of the coating were 130.3°and 80.1°,respectively when the content of MAPOSS was 6wt%,and the coating showed excellent anti-fouling self-cleaning ability after ink coating,soybean oil and pump oil soaking.Meanwhile,the coating was superior to FPA and PA electrophoresis coating in water resistance,friction resistance,acid and alkali resistance.Set the synthetic MAPOSS/ fluorine acrylate synergistically modified acrylic resin(MFPA)electrophoresis paint as example,the influence of cathodic electrophoresis coating and baking process parameters on the appearance and thickness of electrophoresis coating was investigated.Research shows that flat electrophoresis coating of 22.5μm in thickness,good gloss and hardness in appearance could be attained when the electrophoresis lacquer liquid solid content was 10 to 15%,electrophoresis voltage was 60 ~ 80 v,electrophoresis time was 100 ~ 100 s,electrodes space was 10 ~ 12 cm,electrophoresis bath temperature was 25 ~ 30℃,baking temperature was 150 ~ 160 ℃,and baking time was 30 min. |
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