Study On Preparation And Properties Of UV Curable Optical Clear Pressure Sensitive Adhesive Film

Optically clear adhesive(OCA) was a kind of pressure-sensitive adhesive possessing high light transmittance, high holding tack and good aging resistant performance, which was used for bonding optical device. The OCA pressure-sensitive adhesive was prepared mainly by solvent and non-solvent methods, among them, UV curable OCA pressure sensitive adhesive has become a hot research because of the advantages of no solvent evaporation and no residual solvent. The aim of this study was to synthesize a kind of UV curable photosensitive resin prepolymer, and OCA pressure sensitive adhesive film possessing high holding tack and high light transmittance was prepared by UV curing method, with adding various additives.In this study, with poly propylene glycol(PPG2000), isocyanate TDI and hydroxy ethyl acrylate(HEA) as the main material, p-hydroxy phenyl ether as polymerization inhibitor, HDDA as diluent, the polyurethane acrylate was synthesized, which had reasonable molecular weight and molecular weight distribution, suitable viscosity and high light transmittance. The influences of synthesis process and monomer ratio on the chemical construction, molecular weight and molecular weight distribution of PUA were researched through analysising FT-IR and GPC. And the influencing factors of PUA transmittance and viscosity were discussed. The results showed that: the synthesis system of PUA was that the first step was at 60? for 1 hour after heating to 65? for 1 hour, the second step was 80? for 3 hours, and when the monomer ratio of TDI, PPG and HEA was 2.3:1:2, the contents of inhibitor and diluent reached to 0.3% and 20% respectively, the synthetic PUA was colorless and transparent liquid, whose molecular weight reached to 11200 points and molecular weight distribution width index was 2.58, whose viscosity was 15000 mPa.s.With synthetic PUA as UV curable oligomers, OCA pressure sensitive adhesive film was prepared by adding various additives. The effects of various components on the properties of OCA pressure sensitive adhesive film were studied by testing the optical properties, bonding properties and aging properties. The results showed that: when the content of light initiator(BP), tackifying resin, and the reactive diluent were respectively 5%, 9% and 7.5% in PUA, it was extremely excellent for the optical performance, bonding performance and stability of OCA pressure-sensitive adhesive film. Its light transmission rate reached to 98.5%, the initial tack reached to 9 ball, holding tack were 22 h, 180° peel strength reached to 1.8KN/m. The thermal stability and resistance to aging properties were excellent.