Study On Liquid Optical Acrylic Adhesive And Its Properties

With the rapid development of modern industry, the traditional adhesive has been unableto meet the requirements of industrial production because of its defects. Compared to the traditional adhesive, Liquid optical clear adhesive(LOCA) is a kind of one that gets advantages over curing speed, low heat, light transmittance, refractive index, soft film, impact resistance, broader applicability and so on. These are the reason why people pay more and more attention on it. In this paper, a new UV-curable acrylic adhesive with good combinational properties was introduced. This adhesive was prepared by using self-synthesized ploy-butyl acrylate, photo-initiator and reactive diluent monomer.Firstly, the acylic trimethylcyclohexanol ester was synthesized by acrylic acid and 3,3,5 – trimethylcyclohexanol, while the methylbenzene working as water carrying agent and the p-toluenesulfonic acid working as catalyst. When the mass ratio of the p-toluenesulfonic acid was at 1.0%, the mole ratio of acylic acid to trimethylcyclohexanol was at 1.2 and the temperature was at 125℃, the conversion rate of this reaction could reach to 94.86%.Secondly, an acrylate prepolymer was synthesized through semi-batch solution polymerization process in acetone, with AIBN as thermal initiator and 1-dodecanethiol(NDM) as chain transfer agent. The optimum conditions were as follow: to the whole mass of monomer, the mass ratio of 2,2’-Azobis(2-methylpropionitrile)(AIBN) at 1%, 1-dodecanethiol at 2% and the temperature at 75 ℃. The viscosity of acylic trimethylcyclohexanol ester prepolymer synthesized under this conditions was at 12000 m Pa·s.Finally, the target adhesive was prepared by prepolymer, 1- hydroxy cyclohexyl phenyl ketone, acrylic acid isobornyl ester(IBOA) and tri(propylene glycol) diacrylate( TPGDA). When the mass concentration of reactive thinning agent was 40% and the mass ratio of TPGDA to IBOA was 3:1, the refractive index of the cured membrane was 1.48 and the light transmittance was over 80%.In the assembling of capacitive touch screen, many thin decks were stacked together. Only the high qualified adhesive, which has an excellent liquidity and transparency, can satisfy the requirements.Since the liquid optical adhesive has many good optical properties and flowing resistance, it can be widely used in different field, such as touch screen, LED and so on. Consequently, because of a higher production efficiency and lower cost, the adhesive has a promising future.