Research On Room Temperature Crosslinked And Anti-aging Organosilicon Resin And Coating With High Temperature Resistance

Organosilicone polymer now has a wide variety of products after half a century of development.High temperature resistant organosilicone resin and paint are important materials on which matrix high-temperature protection greatly rely for it's excellent high temperature resistance. Supported by project,the subject further studied the organosilicone resin and coating according to the property requirements needed,high temperature resistance,aging resistance, room temperature curing and other performance for high temperature resistant paint mainly on national defense and military, aerospace,petrochemical, new energy and other industries.In addition,the problems of high temperature resistant organosilicone paint existed in the practical application were taken into consideration.The experiment studied the effects of reaction conditions and catalyst category on the synthetic resin coating performance. The results show that the most important factor to the resin state and the coating temperature resistance is the catalyst,among three catalysts Polyhydric metal carboxylate, HCl and Na3PO4,the catalytic effect of zinc octoate is the best. Optimum level of other factors are: R:Si value of 1.5, Ph:R value of0.4, hydrolysis temperature is 70 ?, time is 2h,condensation polymerization temperature is 120 ?, time is 2h. Liquid resin of moderate viscosity is obtained,number-average molecular weight of the resin——Mn = 2069, molecular weight dispersion coefficient D= 2.18. The coating show good mechanical property and good appearance after being heated, but of serious thermal weight loss, under nitrogen atmosphere, up to480 ?,weight loss is about 45 percent, up to 900 ?, 65.7 percent. Low hardness and poor curing performance of coating require it to be baked and cured at 160 ?. By adding butyl titanate,the coating can be cured at room temperature.Under optimum conditions, studied the effects of different monomer on resin and coating performance. In all the factors, the trifunctional monomers, especially MTES has the greatest influence on the coating property, it can improve the coating hardness and curability effectively, but the coating heated are easily cracked when the MTES is over added. Phenyltrimethoxysilane is added to help improve the flexibility of the coating,but the lower the amount added, the better the overall performance of the coating,indicating that it can reduce hardness, curability and anti-aging properties significantly.The influence of difunctional monomer on coating properties is relatively small, it is beneficial to enhance the flexibility of the coating, but it also has adverse affect to the curability, hardness and other properties of the coating, the amount used should not be excessive. TEOS has moderate slightly weak influence on coating performance,and coating performance degrades with the amount added increasing. Within a certain range,increasing the amount of catalyst can help improve the overall performance of the coating.Room temperature cured resign with good temperature resistance was got. Test results show that the resin of this group number has number-average molecular weight——Mn=946, molecular weight dispersion coefficient D=1.59; curing at room temperature,pot life is about 6h; infrared absorption spectrum and NMR spectrum analysis show that resin structure containing hydroxy(-OH) and-OC2H5 which both disappear after the curing of coating; surface of the coating is smooth and uniform, adhesion is1 class,flexibility is 2mm, hardness is 2H, impact resistant strength is 40 cm. After being explored at 400 ? for 4h,the coating looks good and has certain gloss and toughness,no cracking, chalking or peeling phenomenon is occurred, in addition to a certain color change, up to 480 ?,weight loss is about 45 percent, up to 900 ?, 65.7 percent.Up to400 ?, weight loss rate is around 2.5%, while only 26.2 percent up to 900 ?;anti-aging ability is weaker,After1800 h,chalking, etiolation phenomenon is appeared;water resistance and salt spray resistance are good. By adding an appropriate amount of tetrabutyl titanate, mechanical properties of the coating can improved.By replacing the phenyl-containing monomer with homemade silicone monomer on this basis, optimized formula, trial and error, finally get heat resistant, well anti-aging organosilicon resin and coating with excellent mechanical properties and media resistance, and can be cured at room temperature.The room temperature crosslinked silicone resin prepared has number-average molecular weight——Mn = 907, weight-average molecular weight——Mw = 3487, molecular weight dispersion coefficient D = 3.85; surface of the coating is smooth and uniform, good mechanical properties; After being explored at 400 ? for 4h,the coating looks good and has certain gloss and toughness, nocracking, chalking or peeling phenomenon is occurred, in a nitrogen atmosphere, the decomposition temperature is about 370 ?, excellent heat resistance,up to 400 ?, the weight loss rate is about 7.5 percent, only 14.8% up to 900 ?. After 2000 h UV aging resistant test, no clear color change, chalking phenomenon is occurred, the gloss loss rate is13.4%, the color change ?E is about 1.82.