Method for producing holographic photopolymers on polymer films

A continuous process for the production of photopolymer films, comprising mixing components

• A) a polyisocyanate component which comprises an NCO-terminated polyurethane prepolymer having NCO groups primarily aliphatically bonded and which is based on hydroxy-functional compounds having an OH functionality of 1.6 to 2.05,
• B) isocyanate-reactive polyether polyols,
• C) urethane acrylates and/or urethane methacrylates having at least one aromatic structural unit and a refractive index of greater than 1.50 at 405 nm, wherein the urethane acrylates and/or urethane methacrylates are free of NCO groups and OH groups,
• D) free radical stabilizers,
• E) photoinitiators based on combinations of borate salts and one or more dyes having absorption bands which at least partly cover the spectral range from 400 to 800 nm,
• F) optionally catalysts, and
• G) optionally auxiliaries and additives,
• to form a polyurethane composition, wherein immediately after complete mixing of components A) through E), and optionally F) and G), said polyurethane composition has a viscosity at 25° C. in the range of from 200 to 10,000 mPa·s,
• and coating a support film by the roll-to-roll principle with said polyurethane composition, wherein said support film is moving at a speed in the range of from 0.2 m/min to 300 m/min.