Tin Zinc / Synthesis Mechanism Of Hydroxy-tin-zinc Flame Retardants And Industrial Research

The detailed probation and research on various aspects of hydroxy-zinc-stannate particles and zinc stannate particles had been made in the thesis which include their composition, purification, desiccation, calcination, surface modification, superfine grinding and industrialization etc,.Starting from sodium stannate and zinc chloride, hydroxy-zinc-stannate particles and zinc stannate particles were composed by the way of co-precipitation. We also confirmed the composed products to be the pure hydroxy-zinc-stannate particles through the chemical analysis and X-ray diffraction analysis. After orthogonal test, the optimal technical conditions are as follows: washing temperature-50℃ , composing temperature-50 ℃, zinc to tin ration-1:1. Thermo-decomposability and phase under different temperature of hydroxy-zinc-stannate particles had been investigated by the methods of DSC &TG analysis and X-ray diffraction analysis and the optimal conditions of dehydration are as follows: dehydration temperature of hydroxy-zinc-stannate particles - 165 ± 10±, time- 6.5 hours, calcinations temperature of zinc stannate: 340±10℃, time- 10 hours, turn-over interval: one hour.Application in PVC insulation covering of wire had exhibited outstanding flame-retardant and smoke-suppressant properties of zinc stannate that produced in Bench-scale research of 150 kg in comparison with antimony trioxide and is resulting in the gradual replacement of the latter. After modification research for the surface of particles, the optimal add-on of modifier is 6%. With the surface modifier, the time needed for clarification and separation for the products from the process of composition and washing reduced one third. Diameter dgo of un-dried and un-crashed hydroxy-zinc-stannate particles had reduced from 19.13 m to 13.08 u m and fulfilled the purpose of preventing the particles from enlargement and formulation. The products became very loose after 330℃ calcinations. Superfine grinding for the particles also had been researched and compared the effects from comminution by machine and gas stream, which were D90<8.856 u m and D900<2.509 u m separately. Electron probe and scanning electron microscope were used to observe the shape ofparticles around grinding and found there was no any destruction for the crystal shape by superfine grinding. After surface modification and grinding by JCL300 Two Shafts Micro-crasher, such problems of particles had been solved which include low fineness, mal-distribution, low-compatibility with PVC, lay-wire clogging and partial surface coarseness of products.Polypropylene (PP) and polyvinyl chloride (PVC) with zinc stannate produced in this project as additive has the same flame retardant property (V-0 grade) with the ones added antimony trioxide but greatly increased smoke-suppressant property.Zinc stannate particles developed in this project had reached the standard of fire-retardant zinc stannate.After the commercial test, the same technical and economic data as bench-scale research had been acquired and indicated that the parameters confirmed in this project can be smoothly used in industrial manufacturing.