Study On Preparation And Application Of Waterborne Surface Treatment Agent Used In Synthetic Leather

In order to obtain the appearance and handle of natural leather, synthetic leather surface treatment is usually necessary. At present, most synthetic leather surface treatment agents are solventborne systems. Solvent emissions in the production process not only harm the environment and damage the health of workers, residual solvents in the finished product will also harm the consumer. In view of the above problems, in this thesis, waterborne surface treatment agent without solvent had been prepared, which was applied to the surface treatment of synthetic leather, and solved the problem of solvent pollution in the surface treatment process of synthetic leather. The main research contents and results are as follows:In the paper, waterborne polyurethane WPU1 was prepared with isophorone diisocyanate (IPDI) and polybutylene adipate (PBA) as main raw materials by prepolymerization method. The effect of isocyanate index (R value), the content of hydrophilic chain extender and the molecular weight of polymer polyols on the properties of WPU1 was investigated. WPU1 film was characterized by fourier transform infrared (FTIR) spectroscopy and thermogravimetric analysis (TGA). The results showed that when the R value was 1.4, the content of hydrophilic chain extender was 5% and molecular weight of PBA was 2000, the tensile strength of WPU1 film was 23.1Mpa, the elongation at break was 415%. The result of TGA showed that the initial thermal decomposition temperature of WPU1 film was 236℃ and it was decomposed completely at 476℃, which could meet the basic process requirements of synthetic leather surface treatment.Waterborne surface treatment agent WPU-A was prepared by adding SiO2 matting powder and several suitable additives to WPU1 which was used as film-forming material, and the application performance of WPU-A was investigated. The results showed that when the amount of SiO2 matting powder was 5%, the matting index of WPU-A could reach 81.7% and anti-sticking property could reach grade 5. But this kind of waterborne surface treatment agent had poor hydrolysis resistance. And it needed to increase the amount of SiO2 matting powder in order to improve the matting index, which led to the emulsion stability and mechanical properties decrease, the folding resistance and color fastness decrease. It was difficult to meet the requirements of surface treatment for high performance synthetic leather products.WPU2 matting resin was prepared with IPDI, PBA and hydroxyl terminated polybutadiene glycol (HTPB) as main raw materials by prepolymerization method. The effects of various factors on the structure and properties of WPU2 were studied. The results showed that the stable WPU2 emulsion was obtained when the content of DMPA was 4%. With the increase of R value, the tensile strength of WPU2 film increased at first and then decreased, the elongation at break decreased, coating glossiness decreased at first and then increased, the water absorption of WPU film decreased at first and then increased, the particle size of emulsion increased at first and then decreased, and light transmittance decreased at first and then increased. With the increase of HTPB content, the tensile strength of WPU2 film increased, elongation at break decreased, coating glossiness decreased at first and then increased, light transmittance decreased, and the water absorption of WPU film decreased. The result of TGA showed that the initial thermal decomposition temperature of WPU2 film was 220 ℃ and it was decomposed completely at 507 ℃, which could meet the basic process requirements of synthetic leather surface treatment.According to the characteristics of PVC and PU substrate, waterborne surface matting treatment agent WPU-B and WPU-C were prepared by adding several additives to WPU2 which was used as film-forming material. WPU-B and WPU-C were applied to PVC and PU substrates respectively. The application properties of WPU-B and WPU-C were studied. The results showed that the anti-sticking property of WPU-B and WPU-C were both more than grade 4, the folding resistance of WPU-B and WPU-C could meet the requirement of test. The color fastness and abrasion resistance of WPU-B and WPU-C were better than WPU-A, which could meet the requirements of surface treatment for high performance products.In summary, the results of this paper provide a new method and theoretical basis for the preparation and application of waterborne matting surface treatment agent used in synthetic leather, solving the pollution of solventborne surface treatment agent.