Patent ID: 8778246

Claim:
A method of preparing a cured, non-elastomeric polyurethane urea-containing film comprising the steps of: (a) providing a first component comprising a polyurethane material having isocyanate functional groups; (b) providing a second component comprising a polyamine material having amino active hydrogen functional groups that are reactive with isocyanate; (c) combining the first component with a portion of the second component to form a first reaction mixture; (d) allowing the first reaction mixture to react for a time sufficient to increase the viscosity of the reaction mixture to at least 300 cps; (e) adding the remainder of the second component to the first reaction mixture to form a second reaction mixture; (f) dispensing the second reaction mixture onto a support substrate in a substantially uniform thickness to form an at least partial film thereon, using a film-forming technique selected from: (i) extrusion through a flat film-forming die; (ii) a blown film technique wherein the second reaction mixture is forced through a circular die to form an exiting circular film profile and the exiting circular film profile is expanded by compressed air; and (iii) casting the second reaction mixture into a billet; (g) heating the film on the support substrate to a temperature and for a time sufficient to yield a cured film; and (h) removing the cured film from the support substrate to yield a non-elastomeric, polyurethane urea-containing free film, wherein the dry film thickness of the cured free film is 0.5 to 20 mils (12.7 to 508 microns).