| Textile auxiliaries are indispensable materials in the field of dyeing and finishing process, which can not only help fabric dyeing, but also can give the fabric various features and styles. There are various kinds of product, and textile coating agent is one of the important auxiliaries. Currently, the most widely used products on the market still belong to polyacrylate(PA) and polyurethane(PU), which can be roughly divided into two parts, solvent-based materials and water-based materials. But water-based materials are still used less. In the 21 st century, the world began to pay much more attention to environment issues, and started to research the green product to develop in the direction towards a low-carbon economy. Therefore, our country encouraged the development of textile auxiliaries with good performance, low cost and free pollution. These policies accelerate the development of water-based coating agent, which started and will eventually replace the solvent-based products.As an environment-friendly coating agent, waterborne polyurethane(WPU) has been widely sought after by domestic and foreign companies, because of its advantages, such as low temperature resistance, high elasticity, good adhesive and film formation performance;Due to slow drying, high cost, high water absorption and not good mechanical strength,which cause low hydrostatic pressure, its development and application were restricted.Thus, waterborne polyurethane was modified by organic silicone, acrylic ester and self-crosslinking monomer glycidyl methacrylate(GMA) to promote the water resistance of PU coating agent by investigating the synthesis and coating processes on this project.Firstly, double-bond terminated waterborne polyurethane was synthesized, and then PA monomer and GMA monomer were introduced onto the polyurethane molecule by emulsion polymerization. Finally, A-173 was also added to the reaction on the basis of PUA’s steady synthesis to get the self-crosslinking Si-PUA emulsion. During the research,PU content, GMA content, emulsifier content, reaction temperature, A-173 content and its adding ways were explored by the following tests, including emulsion viscosity, emulsion particle size, monomer conversion rate, gel rate, mechanical property, water absorption,TG, FT-IR, etc. The results show that the increasing dose of PU can help improve theelongation at break but reduce mechanical strength and water hydrostatic pressure of film,the amount of PU should be controlled in 30~40%; the increasing dose of GMA promote PUA’s cross-linking density to decrease the water absorption and increase the mechanical strength, but elongation of film decrease; when the content of GMA get to a certain extent,the emulsion particle size and viscosity increase, the amount of GMA should be controlled in 4%; Compared with using only a kind of emulsifier, the anionic/ non-ionic mixed emulsifier has a better quality of foam stability when the amount of them is about 4%. The reaction temperature at 80 ℃ can get a high conversion rate. When the A-173 was added at last and set at 3%-5%, high water resistance could be achieved, because of the silicone segments and crosslinking structure in film formation. The FT-IR and TG showed that most of the monomers were copolymerized; heat stability of film was improved.Finally, the coating process of Si-PUA coating agent was investigated, including coating amount, baking temperature and baking time. The coating fabric got high hydrostatic pressure and moisture permeation performance, when the coating conditions were as follows: coating amount was about 10 g/m2, baking temperature was about 100℃, baking time was 10 min. On the basis of the process, comparison between PUA and crosslinking Si-PUA in the application on polyester fabrics were made, the result showed that the hydrostatic pressure increased significantly after modification, but its moisture permeability remains to be further researched. |
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