| Aqueous damping coatings were widely used in train carriage,ship cabin,and interior or external wall of buildings since their low content of volatile organic compounds,excellent weather-resistance,easy construction and effective coating.Acrylate emulsions,an dominating organic component in aqueous damping coatings,had been attractive and appealing recent years,especially the pure acrylic emulsion consist of acrylic and acrylate monomer was one of outstanding emulsion applied in functional aqueous coatings because of its mature preparing technology,high production efficiency and good performance.However,the costs of production,mechanical strength and high water-absorption of films of pure acrylic emulsion restricted its application in wider fields,seldom research aiming to aqueous coatings with both good damping property and mechanical strength had been operated in China nowadays.This research adopted technology of semi-continuous pre-emulsification seed emulsion polymerization,styrene(St)and butyl acrylate(BA)copolymer as matrix,methyl acrylic acid(MAA)and epoxy(EP-44)as functional monomers,synthesized a styrene-acrylate damping emulsion.With mechanical blending method,this work prepared a aqueous damping coatings of excellent damping property,good mechanical strength and high degree of application mainly composing of styrene-acrylate emulsion above and talcum powder.This research firstly varied the ratio of BA(soft monomer)and St(hard monomer)and synthesized corresponding emulsion products with semi-continuous pre-emulsification seed emulsion polymerization,comprehensively summarized the damping property and mechanical strength of their films and confirmed the constitution of matrix.The result indicated that the desirable film was the one with BA/St ratio of 60/40,whose peak of “tan?-T” curve was 1.4 and the valid temperature range of damping performance was wide(-5?~50?,tan??0.4),the mechanical and adhesiveness tests were comparatively competitive.With the addition of functional monomers MAA and EP-44,some improvements of the film were achieved,the emulsion particles average size was 245 nm,Poly-diversity Index was 0.0097,and the water-absorption of its film was below 2.5% in one month when the content of MAA was 5wt%,besides,the MAA stabilized the synthesized emulsion product,accelerated the movement rate of emulsion particles,reduced the time cost in filming and largely improved the process of filming.With 2wt% of EP-44 the tensile strength of the film was 1.1MPa and the adhesiveness of coatings on glass culture dish was at 0 class,the EP-44 participated in random co-polymerization on main chain and increased the temperature of heat-decomposition,concluded by the results attained by FT-IR and TG-DSC,at the same time,the EP-44 had less influence on damping property of the film.In order to investigate the combination of styrene-acrylate co-polymer and talcum powder which was the dominating filler of aqueous damping coatings,the research prepared aqueous damping coatings with 800 mesh talcum powder and styrene-acrylate emulsion by the mechanical blending method.The results showed that the compatibility between BA/St co-polymer and talcum coupling by KH-570 was rather good,resulting in better damping and mechanical performance of the coating.When the paints recombined 10wt% coupling glass fiber powder,the tensile shear strength and adhesive force increased to 0.73 MPa and 0.64 MPa respectively,observing the fracture structures of breaking surfaces of the sample obtained from mechanical determinations,suitable content of glass fiber powder as reinforcement tightly implanted into phase of styrene-acrylate polymer and coupling talcum and might became one part of structure of bearing stress.With the addition of talcum powder,the tan? in higher temperature(40?~60?)range of coating apparently increased,the valid damping temperature range was enlarged and the temperature sensitivity of coating was minified. |
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