Synthesis And Properties Research Of Photosensitive Fluoric Poly (Amic Ester)

High-temperature resistant coating is a kind of special coating. It not only has the characteristics of ordinary coatings, but also has the merit of high-temperature resisting. Along with the development of high-tech, especially the development of high-speed aircraft (such as rocket and missile), more demand has been put forward for high-temp- -erature resisting capability of coatings.UV curing is a new"green"radiation curing technology and its application range expands increasingly. Therefore, developing UV curing high-temperature resistant coating has practical significance.Based on synthetic analysis of research developments at home and abroad, the molecular structure and synthesis technology route of fluoride polyamide acid ester had been designed. In this paper, synthesis of fluorine poly (amic ester) (FPAE) by using 4,4'-(hexafluoroisopropylidene) diphthalic anhydride (6FDA), pyromellitic dianhydride (PMDA), 4,4'-oxydianiline (ODA) and hydroxyl ethyl acrylate (HEA) as monomers, and N-methyl-pyrrollidone (NMP) as solvent, was conducted in nitrogen atmosphere. Meanwhile, the synthesis of FPAE by three methods(direct method, mixed anhydride method, TDI method) was carried out and the products'viscosity had been tested. The experiment results shows that the optimum reaction conditions of fluorine polyamide acid (FPAA) synthesis in room temperature are as following: n(6FDA+PMDA):nODA=1.05~1.15, reaction time 3~3.5h.FPAE was characterized by Fourier-trasform infrared spectroscopy (FTIR), ultraviolet spectroscopy (UV), thermal gravimetric analysis (TGA).The results are as following:(1)The wavelength absorption range of UV spectrum of the three products ,which was respectively prepared by direct method, mixed anhydride method and TDI method, are 250~340nm,270~370nm,250~340nm;the maximal wavelength absorption of UV spectrum are respectively 267nm,305nm,282nm; (2) They have good solubility in strong polar solvent(NMP,DMF,DMSO); (3)TGA curves show that FPAE lose weight obviously in the temperature range of 100~300℃, which reflects that FPAE starts imidization and transforms to FPSPI at 100℃. FPSPI does not change significantly in the temperature range of 320-500℃and starts decomposition at 500℃leading to losing weight rapidly.Choosing photoinitiators, monomer and FPAE to make compound coating film, then TGA was use to analyze the solidified coating film. The results are as following: (1) FPAE coating film prepared by UV curing still has heat-resistant property at 300℃;(2) FPAE coating film prepared by UV-heat dual curing still has heat-resistant property at 350℃.