Preparation, Property And Application Of Transparent Hard Organic/Inorganic Hybrid Film

Due to the low surface hardness,transparent plastic is easy to be scratched in use, which makes the loss of operation life and limits extended application.The surface scratch behavior can be reduced effectively through coating a hard protective film on it.Among the three hard films(organic,inorganic,organic/inorganic),the organic/inorganic hard film can integrate good adhesion to substrate of organic film with excellent hardness of inorganic film,which has become the hot study spot of hard film on plastic.Now domestic research in hard film area is lack of systematic and theoretical guide and the properties and application of film is worse than that of abroad.We need to explore deeper and systematic research to provide theory and technical guide for the preparation of hard and stable protective film.The research and development of hard film on transparent plastic and hard hybrid film prepared by sol-gel method-were summarized thoroughly in this paper.With ethylorthosilicate(TEOS),aluminium isopropoxide(Al)and zirconium oxychloride (Zr)as inorganic sol precursors,methylacryloyloxytrimethoxysilane(KH-570)as modifier and the methyltrimethoxysilane(MTMS)as film formation materials(in zirconia sol/organosilicone hybrid film system is aminopropyltriethoxysilane, KH-550),the inorganic/organic hybrid film was prepared on transparent plastic-polycarbonate(PC)by the sol-gel method.The mechanism of sol formation and modification was studied.The process,characters and influence factors of film formation by sol-gel technique were discussed theoretically.The relationship of film composition,structure and properties was studied systemically.The results in this paper have theoretical value and instructive meanings to the research and development of hybrid film prepared by sol-gel method and also to the surface modification and extended application of plastic.Main results were as follows:1.The formation and modification mechanism of silica,alumina and zirconia sol was dissertated in detail.The main reaction of sol-gel technique is hydrolysis and condensation.The sol molecules connected with each other through M-O-M covalent bonds.KH-570 was bonded to colloidal particles through condensation reaction and covered particles with long organic chain,which prevent colloidal particles from aggressive and improved the stability of coating solution.The viscosity of silica sol modified with 20%KH-570 is 5.9mm~2/s after aged for 8 days while unmodified silica sol became gel under the same condition.2.The process,characters and influence factors of silica sol/organosilicone hybrid film formation by sol-gel method were discussed theoretically.The film formation by sol-gel technique is based on chemical reaction,inorganic silica sol condensed with trialkyloxysilane and spread on substrate to form gel film.Then the silica sol/organosilicone hybrid film was prepared after heat-treated.The film has both alkyl chain and inorganic Si-O network,which is an organic/inorganic structure.In the silica sol/organosilicone body,the mol ratio of water and TEOS below 15 is better, higher water and air humidity made coating solution contract to drops on PC.KH-570 When the stress produced during the heat-treated process exceeded film bearing force, the film would crack.The crack expantion is the function of residual stress,film thickness and crack-resistant ability.The organic long chain brought by KH-570 into coating solution improved the crack-resistant ability of film.The silica sol/organosilicone film without KH-570 was easy to crack and with the addition of KH-570 the crack disappeared.The film thickness increased with the ageing time prolonged.The film prepared after coating solution aged for 5 days is easier to crack than aged for 1 day.The thickness of silica sol/organosilicone film was calculated by Envelope method.The film thickness after coating solution ageing for 1,2 and 5 days is 0.88μm,1.18μm和2.90μm respectively.After addition of 20%KH-570 the film thickness is 1.38μm,1.50μm and 2.66μm respectively.The thickness increases with the ageing time prolonged and the thickness of film without KH-570 increased faster.3.The composition,structure and properties of silica,alumina,zirconia sol/organosilicone hybrid film were studied systematically.The silica sol/organosilicone hybrid solution without KH-570 gelled after ageing for 21 days while the viscosity of coating solution with 20%KH-570 was only 9.52mm~2/s after ageing for 34 days.The viscosity of 40%KH-570 modified alumina sol/organosilicone solution was 12.44mm~2/s after ageing for 32 days,lower than 20.62mm~2/s of unmodified coating solution.The addition of KH-570 improves the stability of coating solution.The hardness of PC improved from 2B to HB after coated with organosilicone film.With the addition of silica sol the hardness of coated PC maintained increasing.When the mol ratio of TEOS and MTMS was 2,the hardness of coated PC reached 2H.And when the mol ratio of TEOS and MTMS was above 4, the hardness of coated PC decreased.The light transmittance of silica sol/organosilicone coated PC increased from 88.6%to above 90%.Alumina sol was more effective on increasing hardness than silica sol.When the mol percent of Al and MTMS was 15%,the hardness of coated PC reached 2H.The light transmittance of alumina sol/organosilicone coated PC after ageing for 1 day was above 90%after. When mole pecent of Al and MTMS is 10%,the light transmittance of coated PC decreased TO 87.8%after ageing for 2 days and the addition of KH-570 improved it to 90%.The hardness of zirconia sol/organosilicone film is H.The effect of zirconia sol/organosilicone film on light transmittance of PC changed with zirconia sol content. When mol ratio of ZOC and KH-550 was lower than 1,the light transmittance of coated PC was above 88.6%.4.On the basis of research work above,the application study of abrasion-resistant organic/inorganic film was explored.The silica-alumina hybrid sol/organosilane composition was selected to prepare hard film.The coating solution is stable and can preserve over 1 month with little change of visicosity.The hard coating solution was applied on optical glass made of PC and improve the hardness from 2B to 2H～5H and the light transmittane from 88.6%to above 90%.