Study On Preparation And Performance Of Acrylic Damping Emulsion

China's rail transit is developing rapidly.The vibration and noise generated by vehicles during high-speed driving will cause severe discomfort and even health hazards to passengers and residents along the line.Damping materials with vibration and noise reduction functions are more and more widely used in transportation facilities such as locomotives.Environmental protection regulations are becoming stricter and stricter,requiring the use of noise and vibration reduction products with low pollution and low emissions.Water-based coatings have low VOC and are green and safe,so it is necessary to develop green and environmentally friendly water-based damping coatings with excellent damping performance.Water-based damping coatings are mainly composed of emulsion resins,fillers,additives,etc.,of which polymer emulsion is used as the base resin of the coating,and its damping performance is directly related to the noise and vibration reduction effects of the coating.In this paper,two acrylic ester emulsions and their coatings with high damping properties are studied,and their performances are studied according to the relevant standards of rail vehicles.The main research contents are as follows:(1)Preparation of styrene-acrylic emulsion by emulsion polymerization and its damping properties.A series of styrene-acrylic emulsions were prepared by emulsion polymerization.The type and amount of emulsifier,the amount of initiator,the amount of buffer,the reaction temperature and the amount of functional monomer were used to study the conversion of the polymerization reaction system by single factor analysis.The influence of the rate,gel rate,and emulsion stability determines the optimal damping emulsion synthesis formula and process: the emulsifier is added at 1.0% of the total mass of the monomer and SDBS:OP-10=3:2,the initiator is over Ammonium sulfate(APS)and buffer(Na HCO3)are 0.8%,the amount of functional monomer acrylic acid(AA)is 2.0%,and the polymerization temperature is 80°C.The calcium ion stability,freeze-thaw stability,mechanical stability,particle size,viscosity,acid and alkali resistance,salt water resistance,water absorption rate and damping performance of the latex film were tested and analyzed.The results show that the type and amount of emulsifier have a great influence on the calcium ion stability of the emulsion.When the composite emulsifier with anionic emulsifier and nonionic emulsifier is selected and SDBS:OP-10=3:2,the stability of the emulsion At the same time,the damping performance of the emulsion becomes stronger and then weakens with the increase of the amount of crosslinking agent.When the amount of crosslinking agent(DVB)is1.0%,the damping effect of the latex film is the best,and the effective damping temperature range is 16 ? ?32 ?,the temperature range is up to 48 ?,and the maximum damping coefficient tan ?=1.61.This is because the amount of cross-linking agent affects the cross-linking density of the polymer network,and proper cross-linking density can increase the degree of intertwining between polymer networks and improve the damping performance of emulsion;Reduces the ability of the polymer segment to move,thereby reducing the damping performance.Finally,in order to make the emulsion meet different operating temperature environments,damping emulsions with different glass transition temperatures were designed and synthesized,and the damping emulsions were blended to obtain a wider damping temperature range.(2)Study on the properties of silicone modified core-shell acrylate emulsion and its damping coating.A semi-continuous seed emulsion method was used to prepare a silicone-modified core-shell acrylic emulsion: firstly,the reaction monomer was mixed with emulsifier and deionized water,and the core pre-emulsion and shell pre-emulsion were prepared respectively;Part of the core pre-emulsion is added with an initiator to prepare a seed emulsion,and then the remaining core pre-emulsion is dropped into a core layer emulsion;finally,a shell pre-emulsion is added to prepare a shell layer emulsion.The effect of the addition method and the amount of?-methacryloxypropyltrimethoxysilane(KH-570)on the polymerization system and the performance of the emulsion were studied.The results showed that when 30% of the shell pre-emulsion was left When KH-570 was dropped,the conversion rate of the emulsion polymerization system was the largest and the gel rate was the smallest.The particle size,calcium ion stability,freeze-thaw stability,mechanical stability and other properties of the emulsion were tested and characterized.The transmission electron microscope(TEM)observed that the latex particles were uniformly distributed in a spherical shape,and the particle size was about 150 nm.The coating structure,that is,the core-shell structure;the addition of KH-570 has a great influence on the damping performance of the latex film.The results show that the optimal addition of KH-570 is1.0%,and the effective damping temperature range of the core-shell emulsion is 16?63 ?,the effective damping temperature range is up to 47 ?,and the maximum damping coefficient tan ? is 1.82.Adding too much or too little KH-570 will reduce the damping performance of the latex film.Finally,the emulsion is blended with pigments,fillers,dispersants,defoamers,etc.to prepare a water-based damping coating,and the appearance,construction performance,acid and alkali resistance,heat resistance,low temperature impact resistance of the damping coating film,Salt spray resistance and composite loss factor were studied and analyzed.