Synthesis Of Hydroxyl Acrylic Latex And Preparation Of Its Waterborne Coatings

The environmental friendliness of waterborne coatings is one of the main development directions of coatings.Water based hydroxy acrylic latex is used to prepare two-component water-based latex paint(latex paint),which can be cured by room temperature curing agent such as polyisocyanate,water-based wood paint,etc.,and can be cured by high temperature curing agent such as amino resin to prepare anti-corrosion paint for color steel plate,etc.However,hydroxy acrylic latex,like other latex coatings,is difficult to prepare high gloss coatings(such as 60°gloss>90),which is not conducive to the application of some fields.In this paper,from the analysis of the film-forming mechanism of latex coating,the accumulation and fusion of latex particles into the film,the composition of latex copolymer and the morphology and structure of latex particles directly affect the physical and chemical properties of latex film,such as strength,hardness,permeability and luster.Through the optimization of formula design and synthesis process design,we can reduce the particle size of latex,improve the stability and conversion rate,and reduce the cohesion rate.The main contents include the synthesis of hydroxyl acrylic dispersions,the synthesis of core shell hydroxyl acrylic emulsion and the preparation and properties of the corresponding waterborne coatings.1.Synthesis of waterborne Hydroxy Acrylate Latex.Methyl methacrylate(MMA),butyl acrylate(BA)and hydroxypropyl methacrylate(HPMA)were used as the main monomers.Anionic emulsifier 073 and non-ionic emulsifier 407 were compounded according to the ratio of 2:1.The total amount of emulsifier was 3%of the amount of monomers The amount of spa accounts for 3%of the amount of HPMA monomer,the amount of dodecyl mercaptan accounts for 0.2%of the amount of monomer,and the content of hydroxyl group accounts for 1%of the amount of latex copolymer.Through the pre emulsification polymerization process,the hydroxy acrylic latex is prepared,with the solid content of 47%,the particle size of about 90nm,the coagulation rate of 5/10000,the monomer conversion rate of>99%,and the stability of 5%calcium ion.2.Synthesis of core-shell hydroxy acrylic latex.The two step seed emulsion polymerization was carried out with methyl methacrylate(MMA),butyl acrylate(BA)and hydroxypropyl methacrylate(HPMA)as the main monomers.The core shell type hydroxyl acrylic latex was composed of the composition of the nuclear layer copolymer,the monomer of the shell monomer,the type and dosage of the core shell monomer ratio,the hydroxyl functional monomer,the type and dosage of the emulsifier.The synthesis process and the influence rule of latex structure were studied,and the synthesis formula and process were optimized.The results showed that in the two step seed polymerization,the core shell mass ratio was 1:1,the core layer polymer glass temperature was 70 degrees,the shell polymer glass temperature was 10 degrees,the shell HPMA dosage was 10%of the shell monomer consumption,and the emulsifier was 3%of the monomer consumption,the particle size of the core-shell hydroxyl acrylic latex was stable at 100nm,the gel rate was lower than 0.1%,5%calcium ions.Stability through.3.The hydroxy acrylic latex and core-shell hydroxy acrylic latex were blended into water-based varnish and water-based white paint,and 325 amino resin was used as curing agent to prepare two-component water-based hydroxy acrylic amino paint.Spray on steel plate and bake at 130℃,varnish film 60 ° gloss>90,pencil hardness 4h,high adhesion Class 0,impact resistance:positive impact/recoil 120/80,(kg*cm),flexibility 0.5mm,good medium resistance.The white paint with a color to base ratio of 0.5:1 also has high gloss and good physical and mechanical properties.