Preparation And Application Of High Performance Polyurea Functional Coatings

Polyurea coating,with unique characteristics such as high performance,enviromental friendly and fully curing,has been widely applied in steel structure corrosion protection,building waterproofing and concrete protection,etc.since its invention in the 1980 s.However,its disadvantages of complex construction technology,single function and high cost highly restrict the commercial competitiveness of polyurea products.Therefore,it is an inevitable trend to develop polyurea coatings with multifunctions and easy operation while maintaining high performance.Meanwhile,polymer coatings are often subjected to complex stress environment during practical applications,resulting in irreversible damages which affect its protective effect and aesthetics.The development of coatings with high mechanical strength and self recovery ability is an effective way to solve this problem.To settle these problems,we prepared a class of functional polyurea coating by introducing different modified fillers into different polyurea resins utilizing simple physical blending.Then,a high performance polyurea coating with self recovery ability was prepared by introducing asphalt emulsion to modify one component polyurea.The specific research contents are as follows:Firstly,based on the functionalization of polyurea coatings,a new type of highperformance polyurea reflective thermal insulation coatings was prepared in terms of two aspects which respectively were reflective thermal insulation efficiency and mechanical properties.The relationship between the ratio of composite nano beads and the reflective heat insulation efficiency of polyurea coatings was studied by orthogonal experiment.And the SEM(Scanning electron microscope)are uesd to characterize the surface morphology of coatings with different formulations.According to this,the reflective heat insulation mechanism and the effect of the amount of nano beads on the mechanical properties of Polyurea Coatings were analyzed.The results showed that properly doping would significantly improve the reflective heat insulation efficiency of polyurea coating and only sacrifice at the cost of little mechanical properties.When the reflection temperature difference reached about 17 ℃,the maximum tensile strength was up to8 MPa,which was much higher than the reflective heat insulation coating reported so far.This strategy of composite modification was highly universal,and could be used to develop polyurea functional coatings with different functions which was essential to fill the gap in the market.Secondly,this paper uses a "step-by-step method" to synthesize one-component polyurea coatings with different formulations,and systematically studies the rules of effects of isocyanate content(NCO%)and diol ratio on the micro-network structure and macro-mechanical properties of one-component polyurea.The study results have shown that the introduction of small molecule diol can increase the degree of hydrogen bonding of polyurea and enhance its mechanical properties.In addition,hydrogen bonds can be used as sacrificial bonds to give priority to destroying and dissipating energy when the material is deformed to avoid stress concentration.At the same time,the hydrogen bond network can be re-formed after destruction,giving polyurea a self-recovery function to ensure long-term protection.On this basis,we optimize the one-component polyurea synthesis process and prepare a kind of high-performance self-recovery one-component polyurea coating that can be mass-produced,which would have a driving effect on the wide application of one-component polyurea coatings.Finally,in order to further improve the mechanical properties of the one-component polyurea and optimize the cost,this thesis innovatively uses an asphalt emulsion to modify the one-component polyurea to prepare a high-performance asphalt/onecomponent polyurea composite coating.In-depth analysis of the mechanism of asphalt strengthening and toughening polyurea.The results show that a covalent bond is formed between the asphalt molecules and the polyurea molecules,which promotes the uniform dispersion of the asphalt in the polyurea matrix,and at the same time enhances the polyurea-asphalt interface interaction,thereby improving the strength and toughing of the composite polyurea.In addition,the introduction of asphalt do not affect the hydrogen bond network of the polyurea body,and the composite coating still has considerable selfrecovery ability.Asphalt/single-component polyurea composite coatings are easy to achieve large-scale production and are expected to be applied to high-efficiency protection of large equipment.This strategy provides reliable basis and technical support for the preparation of high-performance polyurea functional coatings.