Aqueous polyurethane compositions containing crosslinking agents and their use for heat-active one-coat reverse coating

摘要

This invention relates to compositions of aqueous polyurethane dispersions containing polyurethanes having lateral OH-groups, optionally in admixture with PU-dispersions without any lateral OH-groups, which contain a combination of formaldehyde resins and blocked polyisocyanates as crosslinking agent and, optionally handle-improving agents, silicones and standard additives. The present invention also relates to the use of these compositions for the production of light coatings by the heat-activated, one-coat reverse coating process, in which the PU-composition is applied to a temporary support and dried, after which the (textile) substrate is laminated onto the dry polyurethane film at elevated temperature and pressure and the polyurethane laminate formed is subsequently crosslinked at a relatively high temperature. Mixed crosslinking with formaldehyde resins plus blocked polyisocyanates makes it possible to obtain coatings characterized by outstanding substrate adhesion and wet strength values.