Process for reducing core-set curling tendency and core-set curl of

Abstract

A heat-tempered film element having a core-set curling tendency and a net core-set curl at least about 15% below that of a similar non-heat-tempered film element is provided by a process which comprises heating a sheet or roll of self-supporting, core-set-prone thermoplastic polymeric film, which is non-coated or is coated with one or more layers on at least one surface, under ambient relative humidity of less than 100%, at a temperature in the temperature range of from about 30.degree. C. up to about the glass transition temperature (Tg) of said polymer for 0.1 to 1500 hours, said heating being continued until the change in the number of ANSI curl units that the resulting film undergoes upon subsequent core-setting at 21.degree. C. and 50% R.H. for 2200 hours is reduced by at least 15%, compared to the change in the number of ANSI curl units untreated thermoplastic polymer film undergoes upon core-setting under like conditions. The process is particularly useful for treating a stock roll of radiation sensitive film element comprising a curl-prone thermoplastic polymeric film support, such as poly(ethylene terephthalate), coated with photographic coating layers, to reduce the shelf-life core-set curling tendency and core-set curl of the element, by as much as 60% of that of corresponding, but non-heat-tempered film element in its non-processed, as well as in its processed, form. The resulting heat-tempered photographic film element is especially suitable for the manufacture of low-curl microfiche (film cards), and of amateur movie film having reduced clock-springing in its processed reverse-wound form.