Study On Synthesis And Properties Of UV-Curable Fluorinated Acrylate Copolymers

Waterborne fluorinated coating has good weatherability, heat resistance, durability, corrosion resistance and super antioxidativity. It is also an enviromental protection and safe coating, and becomes one of hot research topics. At present, the researchers focus on the waterborne processing. However, the properties of the coating are not good enough to the requirement. The UV-curabling technology had many advantages, such as fast curing, little pollution, energy conservation, good performance of the cured product, and was widely used in coating, adhesive and printing ink, etc. It was very significant to prepare a type of waterborne fluorinated coating with good properties cured by UV rays.In this paper, two types of waterborne UV-curable fluorinated acrylate copolymer were synthesized.1. The UV-curable fluorinated acrylate copolymer emulsion was synthesized with2,2,3,4,4,4-hexafluorobutyl methacrylate(HFMA), methyl methacrylate(MMA), butyl acrylate(BA) and1-methacrylate-3-acrylic glycerin double ester by emulsion polymerization.2. The waterborne UV-curable fluorinated acrylate copolymer was prepared with neutralizing by triethylamine after grafting GMA in the side chain of the copolymer synthesized with fluorinated monomer,MMA, BA and AA by solution polymerization.The structure of the fluorinated acrylic copolymers was characterized. The influences of the content of raw material and the condition of reactive process on the properties of the polymer were discussed. Meanwhile, the properties of the cured film were tested, and the influence of the UV-curabling conditions on the copolymer properties was also researched. The main research results were as follows:(1) The UV-curable fluorinated acrylate copolymer emulsion was prepared with HFMA, MMA, BA and1-methacrylate-3-acrylic glycerin double ester, using DNS as a reactive surfactant. The structure of the copolymer was characterized by FTIR, and its thermal property was tested by DSC. The effects of reaction conditions, such as the kind of initiating system, the amount of surfactant, the content of double-functional monomer and fluorinated monomer, on the polymerization of the emulsion were discussed. As shown by the results, the stable UV-curable fluorinated acrylate copolymer emulsion, which could be applied to prepare a good performance coating, could be synthesized by the redox initiator with the amount of surfactant of4～5wt%, double-functional monomer of6wt%and fluorinated monomer of16～20wt%.(2) The waterborne UV-curable fluorinated acrylate copolymer was synthesized with fluorinated acrylic monomer, MMA, BA, AA and GMA by solution polymerization. The copolymer was characterized by FTIR and1H NMR, and its thermal stability was tested by TG. The effects of the dosage of raw materials and the conditions of reactive process on the preparation of fluorinated copolymer and the properties of UV-curable copolymer film were discussed. And the influencing factors of grafted modification and the stability of the copolymer solution were also studied. It was shown that the optimum reaction conditions of the preparation of fluorinated perpolymer were in the reaction temperature of120℃and with the dosage of HFMA of14～18wt%, m(MMA):m(BA)=19:15, dosage of AA of8wt%,dosage of BPO of4wt%. The optimum reaction conditions of grafting reaction were at the reaction temperature of85℃～90℃and with the dosage of GMA of12wt%. In that condition, the cured film had good mechanical properties, with hardness reaching411pencil hardness and an impact resistance of50cm. When neutralization degree was more than90%. the copolymer emulsion was translucent and light yellow, and had good storage stability. The optimum reaction conditions for UV-curing process were that the content of curing agent-Darocur2959was1.0～1.5wt%, the drying temperature was70℃, and the exposure time was12～15s.