Study On Preparation And Properties Of Fluorosilicone Composite Modified Waterborne Polyurethane

Waterborne polyurethane uses water as a solvent to comply with the principles of green chemistry.It has low volatility,low cost,and performance between plastic and traditional rubber.A prepolymer method was used to prepare an aqueous polyurethane emulsion based on 1,4-butanediol adipate glycol(PBA)and isophorone diisocyanate(IPDI).The effects of basic preparation conditions and the amount of additives on the properties of water-based polyurethane emulsion and emulsion film were explored.The results showed that the appearance of the emulsion was better when the reaction temperature at the prepolymer formation stage was 80 ℃ and the reaction time was 3h;,2-Dimethylolpropionic acid(DMPA)and crosslinking agent trimethylolpropane(TMP)have been successfully prepared in different amounts of water-based polyurethane emulsion,of which the content of water-based polyurethane emulsion prepared with DMPA content higher than 3.3% has better appearance and stability;When the content is higher than 0.84%,the emulsion film hardness and water resistance are ideal.The water-based polyurethane is copolymerized and modified by adding a modified material containing a fluorine group,thereby improving the water resistance of the water-based polyurethane emulsion film.Perfluoroalkyl ethyl acrylate was selected as the modifier,and the effect of its dosage on the performance of the emulsion film was explored.The results showed that the addition of modifier can improve the hydrophobicity and heat resistance of the film;when the content of perfluoroalkyl ethyl acrylate is 25%,the water absorption of the film is 12.7%,which is 2.2% lower than before modification.The water-based polyurethane is copolymerized and modified by adding a modified material containing silicon groups,thereby further improving the water resistance and heat resistance of the water-based polyurethane emulsion film.Vinyl triethoxysilane was selected as the modifying material,and the influence of the amount of modifier on the performance of the emulsion film was explored.The results showed that within a certain range,the addition of vinyl triethoxysilane content can improve the water resistance and heat resistance of the film.The perfluoroalkyl ethyl acrylate and silane coupling agent were used to modify the waterborne polyurethane(the ratio of both was set to 1: 1 in all experiments).Two silane coupling agents were selected: vinyltriethoxysilane and tetramethyltetravinylcyclotetrasiloxane,two composite modified emulsions were prepared by copolymerization modification,and the content of composite modifier was explored The impact on the comprehensive performance of the film.⑴For the compound modification of fluorosilicone type 1,the results show that as the content of the two modifiers increases,the water resistance,thermal stability,and adhesion of the emulsion film are significantly improved;when the common content of the two modifiers When it is 7%,the comprehensive performance of the film is the best.⑵For the fluorosilicone type two compound modification,the results show that with the increase of the content of the two modifiers,the water resistance of the emulsion film is gradually improved,and the adhesion is always maintained at level 0;when the common content of the two modifiers is 7.5 %,the acid resistance of the film is ideal.The inorganic physical blending modification of the waterborne polyurethane emulsion was carried out by adding solid nanometer silicon nitride powder,and the influence of the amount of nanometer silicon nitride on the comprehensive properties of the emulsion and the emulsion film was studied.The results showed that the nanometer silicon nitride blend modified the waterborne polyurethane The appearance of the emulsion is not ideal,but the overall performance of the emulsion film is good.Among them,when the amount of nano silicon nitride is 3%,the comprehensive performance of the adhesive film is the best: the hardness of the adhesive film is 51.4HA,the water absorption rate is 8.1%,the adhesion of the coating film is level 1;the thermal decomposition temperature of the adhesive film is completely weightless 450℃,68℃ higher than before modification.