Organosilicon auxiliaries used as interlinking agent for waterborne coatings
Waterborne coatings, especially single-component waterborne polyurethanes, are generally not as good as crosslinked two-component polyurethanes in terms of performance because they are not cross-linked. In order to improve the performance of single-component waterborne polyurethane, often in the formulation of waterborne polyurethane coating after adding crosslinking agent, such as aziridine, aziridine and water-borne polyurethane carboxyl reaction, to provide a certain crosslinking degree, so as to greatly improve the final performance of the coating, such as water resistance and solvent resistance. However, the use of aziridine is limited due to its considerable toxicity. Secondly, the cross-linking speed of aziridine is too fast, so it can only be used as a two-component system. Thirdly, aziridine cross-linking agent cannot improve the adhesion of waterborne polyurethane to the substrate. For this purpose, a variety of new diplomatic coupling agents with different structures have been developed, among which silicone diplomatic coupling agent is one of them. Commonly used organic silicon crosslinking agent containing epoxy group, in the process of paint film is dry, the epoxy group in the diplomatic agent can ring opening reaction with carboxyl in water-based polyurethane, produce chemical bond connection, and through its own crosslinking reaction, thus get a three-dimensional crosslinked structure, formation of organic-inorganic hybrid system, So as to improve the film water resistance and chemical resistance and other properties.