Light polarising film laminate prodn. by casting aq. PVA soln. - contg. organic dichroic chromophore with curtain or meniscus caster useful for polarisation filters and for optical displays

摘要

Prodn. of light-polarising films based on PVA and organic dichroitic chromophore(s) (I) involves casting aq. solns. contg. (I) and PVA. At least 2 aq. PVA solns. are cast over one another with a caster through rising casting slots on an inclined surface, sloping downwards, these are allowed to flow downwards to the edge of the inclined surface and, from there, applied to a carrier supplied continuously to the coating station. Consolidating the PVC film by drying, sepg. it from the carrier and drawing lengthwise are techniques also involved. The lower PVA soln. has a viscosity of 10-50 mPa.s and wet film thickness of 10-50 microns (acceleration film) and the second, contg. (I) in adequate concn., has a viscosity of at least 60 mPa.s. Film contg. (I) has a wet film thickness of 100-600 microns and viscosity of 60-600 mPa.s. Acceleration film pref. contains the same (I) as the next film esp. in the same (I)/PVA ratio. PVA film with a viscosity of 10-60 mPa.s and wet film thickness of 10-50 microns (spreading film) pref. is cast over the more viscous film(s). This contains the same (I) as the film immediately below it, pref. in the same (I)/PVA ratio. USE/ADVANTAGE - Film contg. enough (I) to give the required technical properties can be produced without adding I2. The films are useful as polarisation filters and in optical displays. (9pp Dwg.No.1/2)