Preparation And Properties Of Polyurethane Acrylate Coating With High Refractive Index

With the development of science and technology, polymer optical materials are widely applied in optical discs, optical fibers, building materials, resin lenses, precision lenses and antireflection coatings etc.. Optical resin with high refractive index is an important research direction of optical materials, which can further reduce the curvature and thickness of components, and reduce weight without affecting the ability to refract, which make optical instruments small and lightweight. Optical resin with high refractive index coated by coating with high refractive index can improve various disadvantages such as poor wear resistance, solvent resistance and humidity resistance etc., and avoid the loss of transmittance.The reaction between isophorone diisocyanate (IPDI) and hydroxypropyl acrylate (HPA) was investigated through the investigation of conversion (-NCO) by di-n-butylamine titration. It was found that the reaction rate increased with the increasing of reaction temperature, and no change with the adding rate of HPA. The reaction temperature and the adding rate of HPA had no effect on the final conversion (-NCO) (52%). With the investigation of the prepolymer's rheological behavior by HAAKE viscometer, it was found the prepolymer was a kind of Newtonian fluids in the range from 20 s^-1 to 140 s^-1 on shear rate. With the investigation of the prepolymer's structure by ¹H-NMR, it was found the selectivity of-NCO was about 7, which was not sensitive to the reaction temperature and the adding rate of HPA, and the molar ratio of produces as IPDI:SMU:PMU:DU was about 1:7:1:1.By GPC and di-n-butylamine titration, the catalytic activity of triethylamine (TEA) and dibutyltin dilaurate (DBT) for NCO/SH system and NCO/OH system, and the catalytic mechanism of their mixture were investigated. The results showed that the high catalytic activity of TEA for NCO/SH system, and DBT for NCO/OH system, respectively. The synergetic catalytic mechanism of TEA and DBT mixture for NCO/SH system was that TEA as a co-catalyst and DBT as a main catalyst. And that of for NCO/OH system was that hydroxyl oxygen activated by TEA combined with hydroxyl hydrogen activated by DBT to form a new complex.The synthesis of bifunctional polyurethane acrylate (BPUA), bifunctional polythiourethane acrylate (BPTUA) and trifunctional polyurethane acrylate (TPUA) with high refractive index were investigated. In the synthesis of BPUA, the products of the first step included 5.27% IPDI, 63.03% IPI, 18.75% IPIPI and 12.95% IPIPIPI by GPC and Lorentzian method, but for the second step, viscosity was the dominant factor at the beginning of the reaction, and concentration was the dominant factor at the end of the reaction. In the synthesis of BPTUA, DBT was the most suitable catalyst, according to the effect of catalysts on reaction rate, molecular weight distribution and residual IPDI of the products of the first step, and the storage stability of the end-product. In the synthesis of TPUA, the reaction finished after 10h.With the investigation of the curing process of PUA film by FTIR, BPUA and BPTUA were cured completely, except TPUA. When BPTUA was cured, a little thiourethane bonds were decomposed into -NCO and -SH in strong ultraviolet light. In addition, the properties, such as surface dry degree, refractive index, transmittance, yellow index and hardness of BPUA, BPTUA, TPUA homopolymers, and BPUA/TPUA and BPTUA/TPUA copolymers were characterized.