Preparation And Characterization Of Scratch-resistance And Antireflective Coating On Optical Plastic

Optical plastics,such as those made from Poly-methyl methacrylate(PMMA), poly-carbonates(PC) or diallyl diglycol carbonate resin(CR-39),have several advantages over lenses made from inorganic glasses.In addition to their excellent optical quality,optical plastics offer lower density and higher impact resistance. However,the low stratch-resistance and surface hardness of these plastics causes a fast decrease of the optical quality.In the past years,hybrid organic/inorganic materials,mostly produced by sol-gel processes,have been widely used as scratch-resistant coatings for plastic lenses.This thesis tries to prepare MMA/MPS copolymer by solution polymerization of MMA and MPS,which becomes gel system when mixed with hydrolytic TEOS.Such system is easy to be coated on the surface of PMMA substrate.It discusses the influences,brought by different reaction conditions and compositions,on the copolymerization of MMA and MPS and the coating effect.It was found that the optimum weight ratio of MMA and MPS is 3,when the concentration of BPO is 3%, and the system was mixed with 10%hydrolysis product of TEOS 3 hours after the copolymerization was initiated under 75℃.The coating was coated on the surface of PMMA substrate by Liquid Surface Descending Method.After the thermosetting,the coating can not only enhance the stratch-resistance(gloss loss rate was 31.1%after 40 times of wiping),but has an anti-reflective effect on PMMA as well(peak antireflective was 93.2%).Through the study on GPTMS and the composite system of TEOS/MTMS/DMDMOS,the thesis discusses the key factors,affecting the properties of coating,with different weight ratios and in different reaction conditions.The curing reaction leads to the ring-opening and addition curing reactions among most epoxy groups,which result in favorable adhesion to the substrate.The rest epoxy groups bring about certain flexibility in molecular chain segments.The coating on the surface of PMMA is some 3μm thick and smooth.It has favorable adhesion to PMMA substrate.The coating raises the hardness of PMMA from 2H to 5H,offers good protect to PMMA substrate and obviously improves the transmittance.Moreover, because of the lower free energy of the coating,it has outstanding spreading property on the surface of PMMA.