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Coating Fabric

Is there a pretreatment that would allow better adhesion of moisture curing polyurethane (for water proofing) to woven nylon or crystalline polyurethane fabric?

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Q. I am currently coating cotton fabric with a moisture curing polyurethane for water proofing and abrasion resistance. I would like to switch to woven nylon or crystalline polyurethane fabric but have not been able to get good adhesion. I don’t want to use a two-part polyurethane. Is there a pretreatment that would solve this problem? P.E.

 

A. Most fabrics have a coating called sizing applied at the mill. The sizing on your cotton obviously accommodates the polyurethane coating. On the other hand, the sizing on the woven nylon and crystalline polyurethane fabrics may not and therefore acts as an interference coating inhibiting adhesion of the polyurethane coating.

You can try another supplier of the fabrics, hoping they use a compatible sizing. Another approach is to ask the fabric suppliers what sizing they use and then apply a tie-coat as a primer before the polyurethane. You could also ask for a fabric having a compatible sizing.
 

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