| With the national emphasis on environmental protection issues,a series of policies have been promulgated to reduce the content of volatile organic compounds(VOC)in damping coatings.It has become an inevitable trend to develop green waterborne damping coatings.As the base material in waterborne damping coatings,the performance of waterborne emulsion is particularly important,which plays a decisive role in the film forming performance and damping performance of coatings.This paper mainly studies the synthesis of waterborne emulsion in damping coatings.The main contents include:Study on waterborne acrylate emulsion for damping coatings: Using methyl methacrylate(MMA),styrene(St)and butyl acrylate(BA)as the main raw materials,waterborne acrylate emulsions with copolymerization,core-shell and three-layer core-shell were synthesized,and the properties of emulsions and films were investigated.It was found that when the ratio of soft and hard monomers was 70/30,the effective damping temperature range of the film was-13.4°C～60.7°C,and the loss factor was 1.26.When the core-shell ratio is 20/80,the core-shell structure has the best low temperature damping effect,the effective damping temperature range is-46.5°C～14.05°C,and the loss factor can reach 1.30.The three-layer core-shell film with the outermost glass transition temperature of-30°C has good damping performance at medium temperature,and the effective damping temperature range is-24.8°C～28.31°C.The 70/30 copolymer emulsion and 20/80core-shell emulsion were blended to broaden the effective wide damping temperature range.When the blending ratio was 1:4,the effective damping temperature range of the film was-33.81°C～49.18°C.Acrylic polyether phosphate(P monomer)was introduced into the system to modify the copolymerization and core-shell waterborne acrylate emulsion.It was found that the peak loss factor of the modified copolymer film increased to 1.50,and the hydrophobicity was improved.The water resistance and hydrophobicity of the modified core-shell film were improved.Study on composite emulsion for damping coatings: Waterborne polyurethane/epoxy resin/acrylate(WPUEA)composite emulsion was synthesized by using polytetrahydrofuran glycol(PTMG),isophorone diisocyanate(IPDI),epoxy resin(E-44),methyl methacrylate(MMA),styrene(St)and butyl acrylate(BA)as raw materials.The effects of PU/PA value and E-44 dosage on its properties were investigated.It was found that when PU/PA was40/60,the effective temperature range of the film was-21.83°C～27.20°C.When the content of E-44 is 4%,the damping performance of the film is the best,and the peak loss factor is 0.45.The WPUEA emulsions with semi-interpenetrating network(Semi-IPN)and interpenetrating network(IPN)were constructed by introducing crosslinking agent β-CDs and DVB into the system,respectively.The effects of different crosslinking agent contents on the properties of damping emulsions were investigated.It was found that when the content of β-CDs was 4%,the effective damping temperature range of WPUEA emulsion with semi-interpenetrating network was-21.08°C～17.76°C,and the loss factor was 0.52.When the content of DVB was 2%,the effective damping temperature range of WPUEA emulsion with fully interpenetrating network was-31.28°C～16.01°C,and the loss factor was 0.60.The effect of different amount of graphite on the properties of damping coating was studied by using 4% P monomer modified waterborne acrylate emulsion as the basic emulsion of damping coating.The experimental results show that the dry time and heat resistance of the damping coating have reached the class A index.When the graphite content is 5%,the maximum adhesion of the coating is 0.35 MPa,and the damping temperature range is the widest. |
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