PROCESS FOR REDUCING CORE-SET CURLING TENDENCY AND CORE-SET CURL OF POLYMERIC FILM ELEMENTS

摘要

Abstract of the DisclosureA heat-tempered film element having a core-setcurling tendency and a net core-set curl at least about 15%below that of a similar non-heat-tempered film elementis provided by a process which comprises heating a sheetor roll of se1f-supporting, core-set-prone thermoplasticpolymeric film, which is non-coated or is coated with oneor more layers on at least one surface, under ambientrelative humidity of less than 100%, at a temperature inthe temperature range of from about 30°C. up to aboutthe glass transition temperature (Tg) of said polymer for0.1 to 1500 hours, said heating being continued until thechange in the number of ANSI curl units that the resultingfilm undergoes upon subsequent core setting at 21°C. and50% R.H. for 2200 hours is reduced by at least 15%, com-pared to the change in the number of ANSI curl units untreat-ed thermoplastic polymer film undergoes upon core-settingunder like conditions. The process 18 particularly usefulfor treating a stock roll of radiation sensitive film elementcomprising a curl-prone thermoplastic polymeric film support,such as poly(ethylene terephthalate), coated with photographiccoating layers, to reduce the shelf-life core-set curlingtendency and core-set curl of the element, by as much as60% of that of corresponding, but non-heat-tempered filmelement in its non-processed, as well as in its processed,form. The resulting heat-tempered photographic film elementis especially suitable for the manufacture of low-curl micro-fiche (film cards), and of amateur movie film having reducedclock-springing in its processed-reverse-wound form.-1-