Polymer Structure
Synthetic resins formed by reacting isocyanates with polyols provide a flexible binder for coated fabrics and synthetic leathers. A polyurethane matrix holds pigments and additives in place while providing the necessary mechanical strength for the composite material. This structure can be engineered to be breathable or completely waterproof depending on the chemistry of the base resin.
Coating Integrity
Molecular cross linking within the resin determines the resistance of the surface to abrasion and chemical degradation. In a typical polyurethane matrix, the balance between hard and soft segments allows the material to stretch without cracking. This flexibility is what makes the coating suitable for upholstery and footwear applications.
Adhesion Mechanism
Bonding between the polymer layer and the textile substrate depends on the penetration of the resin into the fabric surface. The polyurethane matrix must wet the fibers thoroughly to ensure that the coating does not peel or delaminate during use. Primers are often used to improve this bond when the base fabric is made of non polar synthetic fibers.
Chemical treatment of the substrate can also enhance the mechanical interlocking between the layers.
Degradation Limit
Exposure to moisture and heat can cause the polymer chains to break down over time through hydrolysis. A polyurethane matrix that is not formulated for high humidity will eventually become sticky or crumble. Selection of a polycarbonate or polyether base can extend the life of the material in demanding environments.
