Synthesis Of Grafted Water-soluble Polyvinyl Butyral And Studies On Their Coating Performance

Polyvinyl butyral is a kind of indispensable resin material, which has been widely applied in the manufacture of laminated safety glass, adhesives, fabric treatment and other areas. However, during the process, N,N-dimethylformamide (DMF),dimethyl adipate (DMA) and other organic solvents are always used as the solvent of PVB, so that it will lead to environmental pollution and its application has been restricted. In this paper, PVB was modified to be water-soluble, and the related performance of the modified product were tested, in order to overcome the shortcomings of the environmental pollution resulted from the application of organic solvents, and expand its application areas.Firstly, grafted polyvinyl butyral material (MPVB-P) was prepared by the modification of polyvinyl butyral (PVB) with phthalic anhydride which contained rigid benzene ring. IR spectra and NMR were adopted to characterize the structure of it. The influencing factors including reaction temperature, reaction time and the amount of catalyst of the reaction were studied by orthogonal experiments, the single factor experiments, and their influence rules on the acid value of MPVB-P was obtained. Then, the grafted materials MPVB-P was further prepared to be salt, and the grafted water-soluble PVB (WPVB-P) was obtained, and later, the coating performance of WPVB-P was tested. The results showed that:compared WPVB-P with the raw material PVB, the hardness index became from5H to6H, and the adhesion level became from1to0. The appropriate synthesis conditions of MPVB-P, with considering both the indicators of WPVB-P and its specific needs in the application process, was obtained as follows:reaction temperature60℃, reaction time6h, the amount of catalyst ω catalys6‰.Secondly, in order to combine the UV curing technology with the grafted waterborne modification of PVB, the grafted MPVB-M which had light-curing activity was prepared with PVB and maleic anhydride that contained double bonds in this work. The structure of it was represented with the characterization method. The effecting factors of the acid value of MPVB-M including reaction temperature, reaction time and the amount of catalyst were studied by the way of orthogonal experiments and the single factor experiments. Then, the grafted water-soluble PVB (WPVB-M) was obtained, and UV curing experiments were done on the WPVB-M, through it the effects of illumination time and dosage of initiator to the molecular weight of product were got. After that, the curing coating of WPVB-M aqueous dispersions and its UV-curing coating performance were tested. The results were showed that:compared WPVB-M with the raw material PVB, the hardness index were unchanged, and the adhesion level became from1to0; after UV curing, compared WPVB-M with the large molecular weight obtained in UV curing experiments with the ones with the similar acid value before UV curing, the hardness index became from the5H to6H, and the adhesion level dropped from0to1; after UV curing, with the molecular weight increasing, the hardness and adhesion had a little change, but the water resistance increased. The appropriate synthesis conditions of MPVB-M, considering both the indicators of WPVB-M and its specific needs in the application process, was obtained as follows:reaction temperature55℃, reaction time6h, the amount of catalyst ω catalys6‰.Lastly, in order to investigate the thermal properties of the cured coating WPVB-P and WPVB-M, the thermal gravimetric analysis was used. Then their thermal degradation mechanism was reviewed with Flynn-Wall-Ozawa (FWO) method, Kissinger method, Starink method and Coast-Redfern method, whereas the first three methods were the multiple scanning methods and the last method was the single scanning method. The results were showed that:the dynamic function of the first step thermal decomposition of WPVB-P is the dynamic function of the second step thermal decomposition of WPVB-P and the first step about it of WPVB-M is the dynamic function of the second step thermal decomposition of WPVB-M is...