| In order to minimize the harm caused by noise and resonance,people continue to develop various vibration and noise reduction technologies.Among them,polymerbased damping materials are widely used in various fields,such as automobiles,rail cars,airplanes,engineering machinery,construction,etc.,due to their convenience in use and good noise reduction and vibration reduction effects.The research goal of this paper is an environmentally friendly waterborne polymer damping coating with excellent damping performance and a wide effective damping temperature range.We will prepare polyacrylate composite latex by in-situ polymerization with epoxy resin and small molecule hindered phenol based on polyacrylate latex.Then it is mixed with inorganic fillers and other additives to prepare water-based polymer composite damping coating.The main research contents and conclusions are as follows:(1)In Chapter 2,we discussed in detail various factors in the preparation of polyacrylate core-shell latex,including core-shell soft-hard ratio,core-shell content,functional monomers and long-chain branched acrylate monomers.Influence on the damping performance of latex.While keeping the total amount of monomers in the core and shell and the total amount of soft and hard monomers unchanged,changing the ratio of soft and hard monomers in the core and shell,a series of latexes with the maximum damping peak gradually changing from low temperature to high temperature are obtained.The hard core and soft shell latex has a wide effective damping temperature range,and the temperature of its maximum damping peak is lower.The soft-core hard-shell latex has no other advantages except for the higher temperature of the maximum damping peak.When the ratio of soft and hard monomers in the core and shell is close,the damping factor of latex is the highest.Compared with being separately distributed in the core or shell,when there are 50% functional monomer acrylic or long side chain monomers in the core and shell respectively,the latex has the highest damping factor,the largest TA value,and the lowest effective temperature range.The longer the side chain of the long side chain monomer,the higher the damping factor,the greater the TA value,and the lower the effective temperature range.(2)In Chapter 3,we prepared epoxy resin(hindered phenol 1010)/polyacrylate latex composite latex,and investigated the amount of epoxy resin(hindered phenol 1010)and its distribution in the latex core and shell layer.The influence of composite latex damping performance.As the content of epoxy resin(E16,E44)increases,the damping factor increases slightly,and the TA value increases significantly.The temperature at the peak of the maximum damping factor gradually shifts to lower temperatures,and the effective damping temperature range gradually expands,that is,the damping performance is realized.The overall improvement.The effect of hindered phenol 1010 on the damping factor of polyacrylate latex is not significant at a lower dosage,which is worse than that of epoxy resin with the same dosage.However,the effect of epoxy resin on the effective damping temperature range of polyacrylate latex is obviously not as good as hindered phenol 1010.When both the core and the shell contain epoxy resin(E16,E44),the latex sample has the highest damping factor and the highest TA value.The maximum loss factor values of epoxy resins E16 and E44 modified polyacrylate latexes with different molecular weights and the temperature at which they are located are basically the same.However,the E16 modified polyacrylate latex with a larger molecular weight has a wider damping temperature range and a larger TA value,that is,it has more excellent damping performance.(3)In Chapter 4,we prepared a composite emulsion coating of epoxy resin/polyacrylate latex and inorganic filler in accordance with the requirements of enterprise product development,and investigated the amount of defoamer,emulsion dosage,crosslinking agent KH570.The particle size of inorganic fillers affects certain properties,including repeated baking resistance,impact resistance,water absorption,paint adhesion,paint film adhesion,fluidity,etc.With the increase of the defoamer content,the occurrence of bulging and cracking of the composite coating is reduced,the form stability is increased,the adhesion of the paint film and the damping coating is increased,and the impact resistance is improved,but the water absorption rate of the composite coating is greatly improved.Too little amount of emulsion can easily cause coating cracks,substandard adhesion,and poor impact resistance.Excessive amount of emulsion can easily cause bulging,poor shape stability,high water absorption,poor impact resistance and other adverse effects.When the crosslinking agent KH570 is used too much,the impact resistance of the composite coating will decrease.If it is too small,the water absorption will increase,the adhesion will decrease,and the shape stability will decrease.The particle size of the mica powder has no great influence on the adhesion and impact resistance of the composite coating.If the particle size of mica powder is too large or too small,the water absorption will increase.The particle size of the mica powder decreases,and the morphological stability of the composite coating increases.When the defoamer content is 0.5 wt %,the emulsion dosage is 25 wt %,the crosslinking agent KH570 is 1 wt %,and the particle size of the mica powder is 300 mesh,the water absorption rate can be 5.1%,and the impact resistance is qualified.The adhesive force is Class 1,and the casting distance is less than 1 mm for composite coatings,which meets customer requirements.Although the maximum damping factor of the composite damping coating is only 1.4,the effective damping temperature range can reach 146 ℃,the TA value is 126.1,and the damping performance is the highest among all systems,which has practical application value. |
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