Preparation Of High Solid Low Viscosity UV-curing Polyesters And The Application In Coatings

UV-curable coatings have the advantages of high performance and environmental friendliness,and meet the"5 E"requirements of coating development.Among them,vinyl oligomers are the main factors affecting the performance of UV cured coatings.Present vinyl resins have shortcomings such as high viscosity,low vinyl functionality,and high cost,making it difficult to meet high-end UV curing technology requirements.In view of this,this topic adopts two routes to synthesize vinyl resin,and uses long carbon chain glycidyl ether and polyether polyol to modify the two resins to reduce the resin viscosity.（1）The vinyl aliphatic polyester was prepared by ring-opening polymerization of acid anhydride and vinyl glycidyl ether,using epoxy compounds without vinyl groups to participate in the polymerization reaction,adjusting the viscosity and vinyl functionality of the resin;The molecular structure and molecular weight of vinyl aliphatic polyester were characterized with FTIR,¹H NMR and GPC spectroscopies,and the effects of the types and proportions of acid anhydride and glycidyl ether on the viscosity and hardness of the coating film were studied.It was found that the use of acid anhydrides containing phenyl rigid groups could significantly increase the hardness of the paint film.The long-chain glycidyl tertiary carbonate（E10P）displayed the best viscosity reduction effect.The molar ratio of acid anhydride,vinyl glycidyl ether and E10P was 4:1:3,the viscosity of the prepared vinyl polyester was low up to 2755 m Pa·s,the number average molecular weight was 1425 g·mol^-1with 1.16 of the molecular weight distribution index,and the UV cured film hardness was high up to H,and exhibited excellent water resistance and alcohol resistance.（2）Vinyl star polyester was synthesized by polyol as the core reacting with acid anhydride to form a half ester,and then reacting with glycidyl methacrylate.The effects of the types and ratios of acid anhydrides and small molecular polyols on the viscosity and coating properties of vinyl star polyesters were investigated,and it was found that the more small molecular polyol hydroxyl functionality,the greater the resin viscosity and coating hardness.At the same time,it was found that the introduction of polyether polyol N210 in the reaction system could reduce the viscosity of the resin to 2025 m Pa·s,and the film hardness was high up to 2H with good impact toughness.The molecular structure of the polyester was characterized by FTIR and¹H NMR spectroscopies.The molecular weight and distribution of the resin were measured by GPC,and the number average molecular weight of the resin was ranged from 1149 to 1645 g·mol^-1with 1.2 of the PDI index,which was close to the theoretical molecular weight.The influence of the compound ratio of vinyl star polyester and commercial polyester acrylate on the performance of the UV cured film was studied,and the type and amount of reactive diluents and the optimal ratio of photo-initiator were optimized,and optimize UV cured film possessed 2H of the pencil hardness,and excellent adhesion and flexibility.