주제: Waterborne polyurethane for new demands of environmental regulations in the textile coating industry

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Waterborne polyurethane(WPU) is an environmentally friendly material with excellent performance characteristics. It has been used in a wide range of applications, such as in flexible coatings for textiles, hard coatings for wood and metallic surfaces, and as an adhesive in the shoe and laminating industry, because a wide range of monomeric materials are commercially available and tailor-made properties can be obtained from well-designed combinations of the monomeric materials. Polycarbonate (PC) diol is superior to other polyols with respect to durability, water resistance, and chemical resistance. m-Tetramethylxylylene diisocyanate (TMXDI) is a diisocyanate uniquely suited for WPU because processing is easy due to low prepolymer viscosity, and the WPU can be designed to be a flexible coating with superior adhesion and exceptional toughness.

In order to prepare waterproof breathable clothes through which water vapor can pass easily but water droplet cannot pass, porous polyurethanes or hydrophilic non-porous polyurethanes are coated on a fabric. These polyurethanes also are being replaced by WPUs. In the preparation of hydrophilic PU, the poly(ethyleneglycol) (PEG) segment, which is hydrophilic and thus water vapor can easily penetrate, is normally utilized as a hydrophilic soft segment to endow high water vapor permeability (WVP). However, the PEG segment can worsen waterproof ability or water resistance to protect the penetration of water in its liquid state. Therefore, for the good balance of WVP and water resistance, a balanced amount and a well-thought-out arrangement of hydrophilic and hydrophobic segments in the PU as well as additional cross linking are important.