Molecular Flexibility Regulation And Performance Research Of Water-based Coating Materials

Water-based coating materials have the advantages of environmental protection,energy saving,safety,convenient to use and so on,and have broad application prospects.However,with the development of social productive forces and the improvement of people's living standards,people's requirements for the process stability,application convenience and environmental protection of the series of water-based coating materials are getting higher and higher,and new requirements and problems continue to appear during the use,which affects the popularization and application of water-based coating materials.One of the reasons is that the molecular structure of water-based coating materials,especially its molecular flexibility,is not deeply studied.At present,people mainly learn from the theories related to solvent-based coatings to study the means and methods of adjusting the flexibility of water-based coating material molecules,and seldom carry out special research on water-based coating material molecules.As a result,people don't know enough about the regulation mechanism of molecular compliance of water-based coating materials,and the regulation means are very limited,which can't meet the needs of the rapid development of water-based coating materials.In order to reveal the relationship between the molecular flexibility and macroscopic properties of water-based coating materials,a series of water-based resin molecules with different flexibility,corresponding emulsions and their coatings were designed and prepared for the main application fields(coatings).Polyethylene glycol hydrophilic component agent series waterborne epoxy-polyurethane resin was successfully synthesized by introducing hydrophilic component agent(raw materials giving different hydrophilicity to synthesized molecules)with different molecular chain length of main chain structure.Waterborne epoxy-polyurethane resin of dimethylol acid hydrophilic component agent series was successfully synthesized by introducing different volumes of hydrophilic component agent molecular side groups.Waterborne epoxy-polyurethane resins of glycol hydrophilic component agents were successfully synthesized by introducing different polarity and symmetry of molecular side groups of hydrophilic component agents.According to the specific molecular structure designed and prepared,the influence of various groups on the molecular flexibility of waterborne resin was discussed.The macroscopic properties of waterborne resin emulsion and coating film,such as corrosion resistance,wear resistance,water resistance and adhesion,were studied,and the preliminary relationship between molecular compliance and corrosion resistance and wear resistance of waterborne coating material was summarized.Through the observation of transmission electron microscope,particle size and distribution,emulsion stability and other tests,the various properties of emulsion were studied,and the effects of different polyethylene glycol,different dimethylol acid and different small molecular glycols on emulsion stability were compared:the particle size of each emulsion prepared is small,the distribution is uniform,the appearance of particles is regular spherical,and the emulsion is in a stable dispersion state;the smaller the particle size of emulsion,the narrower the particle size distribution of emulsion and the better the stability of emulsion;to a certain extent,the greater the molecular weight of polyethylene glycol,the smaller the volume of dimethylol acid side groups,and the more symmetrical the distribution of small diol side groups,the better the stability of emulsion.The effects of different polyethylene glycols,different dimethylol acids and different small molecular glycols on the hardness,wear resistance and corrosion resistance of the films were studied,and the adhesion,flexibility and heat resistance of the films were tested.SEM images show that the films are flat and smooth,and there are no irregular microphase areas such as cracks and spots,and there is no obvious shrinkage in the curing process,so the film-forming performance is good;the better the flexibility of resin molecules,the better the corrosion resistance and hardness of the corresponding coating,and the flexibility of resin molecules is positively correlated with the hardness and corrosion resistance of the coating;The better the flexibility of resin molecules,the worse the wear resistance and the smaller the contact angle of the corresponding coating,the flexibility of resin molecules is negatively correlated with the wear resistance and contact angle of the coating.With the increase of flexibility of polyethylene glycol,dimethylol acid or micromolecule diol,the hardness and water absorption of the coating film increase,the wear resistance decreases,and the corrosion resistance to water,acid and salt deteriorates slightly.However,the impact resistance,flexibility and adhesion of the prepared films are all grade 0,and the comprehensive properties are excellent.The regulation of molecular compliance and its influence on macroscopic properties obtained in this paper are helpful for people to understand the regulation mechanism of molecular compliance of waterborne coating materials and master the regulation means and methods of molecular compliance of waterborne coating materials;it is beneficial to improve the performance of water-based coating materials,at the same time,it is beneficial for people to understand the relationship between molecular compliance of water-based coating materials and their macroscopic properties,which provides an effective way for people to improve the performance of water-based coating materials by regulating the molecular compliance of waterbased coating materials.