Synthesis, Structure & Character For Application Of Organic/Inorganic Composite Antistatic Film

In recent years,with great development in technology, all kinds of electronics products play more and more important role in our lives, meamwhile it brings us the massive electronic pollution, especially, the electromagnetic radiation. The electromagnetic radiation can induce the human cancer cells growing up, the cardiovascular system disease, and so on. Antistatic electric field from accumulation of antistatic charges is the one of reasons what result into electromagnetic radiation. So many researches focused on antistatic material for eliminating the electromagnetic radiation.To produce an antistatic film on the surface of the electronics is a good way to solve the problem. Form 1980s, The big companies such as Hitachi Ltd.Toshiba Ltd. in Japan and Samsung company in Korea, had begun to develop antistatic thin film for display terminal and had mastered the key technique in preparing anti-static-electricity sol and film. And the relavent comercial products had been produced.The domestic anti-static-electricity sol for use all depended on import. The present project prepared antimony-doped tin oxide nano-particles with hydrothermal method ,and sol of SiO₂ matrix with sol-gel technology,which are main two parts(conductive material and coating material) of the antistatic sol. With this two material,we composed the compound antistatic sol and thin film. And studied the related theoretical foundation and the technologies for application. We have successfully developed antistatic sol for use and applied it in several domestic enterprises. The antistatic product can totally substitute the imported one. This technology can also be applied in fields such as electronics,printing and so on. The main contents of the study are as follows: 1) Preparation and property of nano-sized electric conductive particlesThe Sb doped SnO₂ (ATO) nano-sized particles were prepared by hydrothermal method with SnCl₄·5H₂O and SbCl₃. The particle size of ATO powder and electricity according with the doping amount of Sb and the thermal process was studied.In this study, the particle size of ATO powder decreased as the increase of the mount of Sb (from 2a.t.% to 40a.t.%). The resistance of the powder get the lowest value at 0.012Ω·cm when the doping amount of Sb is 11a.t.%. The crystallization of ATO particle was controlled by activity energy in 3 steps: low activity energy (1.18KJ/mol) step from 200℃ to 400℃, the temperature range from 400℃ to 600℃, and the step of temperature above 600℃. The resistance of the ATO powder decreases according to the increase of the temperature and gets the lowest value at 600℃. (2)Preparation and properties of conductive film by sol-gel methodSb doped SnO₂ sol and ATO film were prepared using inorganic salt of Sn, and the mechanism of hydrosis and polymerization during above process was studied. The effects of doping of Sb on the structure and properties of the thin film were also studied.It was found that SnO₂ sol prepared by anhydrous SnCl₄ has high stability and the gelating time goes up to more than 110 days. The molecules in the sols exist as monomers under 200 degree centigrade, above which degree the polymerization begins forming the Sn-O-Sn bonds,until the SnO₂ crystal comes into being at 500 degree centigrade. The doping of Sb can hold up the growth of SnO₂ crystals, which makes the SnO₂ crystals finer in the ATO film. The concentration of conductive carriers in the ATO film first increases then decreases with the doping of Sb, getting a maximum 7.2×10¹⁹/cm³. Also is mobility of the films, which got a maximum 2.55 cm²/VS at 6 a.t % Sb. The resistance of ATO films first decreases then increases with the doping of Sb, reaching a minimum 0.048 at 8 a.t % Sb. (3)Preparation of and Characteristic study on the coating material silica solSilica sol was prepared with raw material of TMOS, and the kinetics model of silica sol gelation was revealed. The influences of parameters of craft and properties of sol on hardness of SiO₂ thin film were studied.The relationship of concentration of reactant c, amount of water r, agingtemperature T and gelation time t_g of silica sol was as following: t_g = 9247r^-0.862 ;t_g = 1662c^-0.2525 ; lnt_g =-28.74+95.67/RT; and activity energy of gelationprocess at certain condition is 95.67KJ/mol. Hardness of SiO₂ thin film arrives at 7H～9H(pencil hardness) after heat treatment. (4) Composite antistatic sol and filmATO-SiO₂ composite antistatic film was prepared using SiO₂ sol and Sb doping SnO₂ sol. The relationship between SiO₂ and SnO₂ molecular in the film was studied during anneal course, and the influence of SnO₂ on the structure and property of the film was revealed.The conductive SnO₂ distributes evenly in the composite film. SiO₂ and SnO₂ restrain each other's crystallization during the heat treatment. The crystallization of SiO₂ was obviously restrained while the amount of SnO₂ increases.Stable composite antistatic sol and PEDT-SiO₂ composite antistatic film was prepared using PEDT as a conductive material and SiO₂ as base material. The conductive theory was discussed and the relationship between ageing course and SiO₂ structure and film properties was studied. It was found that the changing trend of conductivity with PEDT amount increasing can be divided into 3 phases,which is similar to the law of conductive compoud polymer. And thin film from long aging time has high "threshold of inleakage".PEDT-SiO₂ composite sol had been produced by Ningbo Jirong electronic material Ltd., and the product was used by Shanghai Yongxin color display tube Ltd.. the properties of the product is similar to the imported ones.