Preparation Of Dangling Chain Waterborne Polyurethane-acrylate Composite Emulsion And Its Application In Damping Coatings

Noise pollution is one of the three major public hazards in the process of social development,so vibration and noise reduction materials have attracted the attention of many researchers.As a kind of polymer damping material,polyurethane(PU)elastomer has been favored by many researchers because of its excellent comprehensive properties and special structure.But with the improvement of people’s environmental awareness,the traditional solvent-based PU will be gradually replaced by more safe and environmentally friendly waterborne polyurethane(WPU).The use of WPU water-based coatings is also increasing year by year,and its water resistance,corrosion resistance will reduce its service life and effect.Based on this,a water-based damping coating with strong water resistance and corrosion resistance is needed for development.The specific contents are as follows:(1)In this paper,methoxypolyethylene glycol(MPEG),isophorone diisocyanate(IPDI)and 1,1,1-tris(hydroxymethyl)propane(TMP)were used as raw materials for polycondensation reaction.a series of dangling chain polyol(DCP-n,n expressed as average molecular weight of MPEG)with different length was prepared by changing the molecular weight of MPEG(molecular weight: 200,350,500,1000 and 2000 g/mol).DCP-n was introduced into the main chain of PU,which can increase the friction between WPU molecular chains and improve the damping performance.The use of hydroxyethyl methacrylate(HEMA)as the end-capping agent can form a chemical bond between WPU and polyacrylate(PA),thereby improving the compatibility between WPU and PA.Then,methyl methacrylate(MMA),2-ethylhexyl acrylate(EHA)and initiator were added for free radical polymerization,and dangling chain waterborne polyurethane-acrylate(DC-n-WPUA,n expressed as average molecular weight of MPEG)emulsion was obtained.The hydrophobic properties,mechanical properties,thermal stability,and damping properties of DC-n-WPUA by the length of DCP-n were investigated by contact angle meter,mechanical property testing,thermogravimetric analysis(TGA)and dynamic mechanical analysis(DMA).The test results show that the DC-500-WPUA has excellent comprehensive performance.The effective damping temperature range is-32.0 ～ 45.9 ℃(77.9 ℃),and the hydrostatic contact angle is 106.1°.(2)Using DC-500-WPUA as the base emulsion,a series of water-based damping coatings with different HTMS contents were prepared by adding hexyl trimethoxy-silane(HTMS),sericite,thickener and defoamer.The effects of HTMS content on fluid properties,damping properties,water resistance,corrosion resistance and thermal stability of water-based damping coatings were also studied.When the content of HTMS is 6%,the coating has excellent comprehensive performance.The effective damping temperature range of-31.21 ～ 94.67 ℃(125.88 ℃)is 61.6% wider than that of the base emulsion,the static water contact angle is 122.0°,and the yield value is ty=5.67.