Study on Polymercaptans used For Optical Resin

The optical resin polythiol is one of the main material used in the preparation of optical lenses, until now,domestic industrialization has not been reported.In order to Applying optics field, high product quality should be required.The high sulfur content determines the high refractive index and low dispersion of the polythiocarbamate optical resin material. By increasing the molecular weight of the thiol to prepare polymercaptan not only greatly reduces the fumes, but also polyfunctionalization of -SH gives the resin a bulk structure to present excellent properties. With a simple and environmental protection production process of,polymercaptan are easy to achieve in laboratory or industrialization, but the product is currently subject to international monopoly.Combination of the company valuable resources such as mercaptoethanol,the development of polymercaptan applied to high refractive index resin has important significance. In this thesis by the synthesis of intermediate triolcompounds, intermediate isothiuronium salts, polymercaptan compounds and the post-treatment process were studied.

In the preparation of intermediate triol compounds.one-step method was used to prepare triol intermediates, bycontrolling pichlorohydrin: mercaptoethanolNaOH=1:1.95:1.1 temperature at 50℃，time for 1.5-2hhighest concentration of 94.8% oftriol compounds could be achieved. In the process of preparation of isothiourea salt,Optimization conditions were got, reaction ratio of epichlorohydrin:thiourea=1:3.5epichlorohydrin:hydrochloric acid(mol)=1:4.5,reaction temperature at 100℃.In the study of the preparation process of polymercaptan, the optimized reaction ratio at epichlorohydrin:sodium carbonate(mol)=1:6 reaction temperature at 60℃.In the post-treatment process studythe steaming temperature is preferably 60℃ and molecular sieve as desiccant.The feasibility of the small-scale process was verified by the enlargement experiment and he product indexwas qualifiedthe average content was 94.0%the average refractive index was 1.6328,the average yield was 93%.The product was identified as the target product by NMR,IR and liquid-mass spectrometry.

By the investigation the effection of the main content ,water content,refractive index and chroma of polymercaptan on the properties of the resin,obtained:polymercaptan main content,consistent with the influence of the refractive index of resin lenses;With main content and refractive index increasing,impact properties first rised and then decreased. refractive index and glass transition temperature gradually increased haze propertity first rised and then decreased,yellow index refers gradually reducedthe transmittance kepted no effect.The optimization range of polymercaptan content was between 92.3-96.1%the refractive index was between 1.632-1.633.By controlling polymercaptan chroma below 15, water content below 1500ppm,resin performance are excellent.The optimization preparation conditions of polymercaptan can meet the requirement of the above performance indexes.Comparing the raw material indexes and lens properties, polymercaptan self-produced are better than the imported.