Study On The Preparation And Properties Of Abrasion-resistant Transparent Coatings Based On Siloxane Polymers

Silicone polymers possess many excellent performances in various fields, especially in the coating industry due to their unique chemical structure. Silicone hard abrasion-resistant coating, as a protective coating on optical plastic surface shows outstanding performance in improving the abrasion resistance property, which is one of the most widely used applications with good economic and social benefits. In this thesis, we focused on preparation and properties of the abrasion-resistant transparent coatings based on siloxane polymers.(1) Epoxy acrylate resin was synthesized and the effect of different molar ratio on the yield was investigated. Silane coupling agent MPS (methacryloxy propyl trimethoxyl silane) was used to modify the epoxy acrylate resin to obtain transparent abrasion-resistant coating on PMMA, and the effect of MPS content on coating’s properties was investigated. It was found that surface of the coatings contained 10%, 15% and 20% MPS was flat and smooth. By coating performance test, it was found that coating pencil hardness was up to 6 H after thermal curing and adhesion was one degree. The transmittance of the transparent abrasion-resistant coating was about 92%. The abrasion-resistant coating also improved the anti-abrasion property of PMMA substrate. The water and ethylene glycol contact angles of coated PMMA substrates were increased with increase in the MPS content, imparting lower surface free energy to the coating surface.(2) TEOS/GPTMS sol was synthesized via sol-gel method to obtain abrasion-resistant transparent coating. The effect of molar ratio of TEOS (tetraethyl orthosilicate) to GPTMS (3-glycidoxypropylthrimethoxysilane) on coating morphology, structure and properties was investigated. It was found that when molar ratio was 2.33 and 4.00, coating appearance showed wrinkling or cracking phenomenon. By coating performance test, it was found that hardness was up to 5 H and adhesion was one degree. Moreover, pencil hardness and adhesion were increased with the extension of aging time. The light transmittance of the abrasion-resistant transparent coating was about 93%, which was increased with the increase in aging time. The abrasion-resistant coating improved the anti-abrasion property of PMMA substrate, which was proved by the minimum weight load made noticeable scratches on the coating surface. The water and ethylene glycol contact angles of the coated PMMA substrates were increased with increase in TEOS content, imparting lower surface free energy to the coating surface.(3) Irgacure 184, Irgacure MBF and Irgacure 907 were chosen as photoinitiators to prepare UV-curable abrasion-resistant transparent coating based on MPS-modified bisphenol A epoxy acrylate resin. The effect of photoinitiators on coating properties was investigated. It was found that the photoinitiators used had different absorption bands. Irgacure 184 showed absorption bands at 205 and 248 nm and Irgacure 907 showed absorption bands at 204,238 and 305 nm, while Irgacure MBF showed absorption bands at 204 and 256 nm. All the coatings showed better pencil hardness and adhesion as well as light transmittance in comparison with blank PMMA substrate. Moreover, coatings based on MPS-modified bisphenol A epoxy acrylate resin with Irgacure 907 as photoinitiator showed better light transmittance and abrasion resistance properties.