GB1107657A - Polyester film support with low aldehyde content - Google Patents

Abstract

A photographic film support comprises a biaxially oriented and heat treated sheet of thickness between 0.005 and 0.015 inch of a linear polyester of a dicarboxylic acid and a glycol which contains sufficient of an organic phosphorus compound to reduce the content of acetaldehyde to below 7 p.p.m. per 0.001 inch of thickness measured at the time of the original formation of the sheet. The sheet may contain 5-150 p.p.m. by weight of elemental phosphorus. Suitable phosphorus compounds are esters of phosphoric and phosphorous acids, particularly esters of polyhydroxy compounds, and especially cyclic phosphite esters of polyhydroxy compounds. Materials specified are those derived from pentaerythritol and bisphenol A and triphenyl phosphite and from neopentyl glycol, 1:4-cyclohexanedimethanol and triphenyl phosphite, and the phosphites of trimethylolethane, trimethylolpropane and trimethylolbutane, tridecyl phosphite, tri (2-ethylhexyl) phosphate, distearyl and diphenyl pentaerythritol diphosphites, and tris (2:2:4 - trimethylpentyl) phosphate. General formulae are given for monomeric and polymeric cyclic phosphites which may be used. In examples films of polyethylene terephthalate are prepared containing 0.1 weight per cent of tridecyl phosphite, tri (2-ethylhexyl) phosphate, and di-(neopentyl glycol) 1:4-cyclohexanedimethanol diphosphite. Other suitable phosphorus compounds are said to be ethyl dihydrogen phosphate, triphenyl phosphite and tris (2:2:4-trimethylpentyl) phosphate. The polyester may be derived also from e.g. 2:6-naphthalene dicarboxylic acid and/or from e.g. a 3:1 mixture of 1:4-cyclohexanedimethanol and ethylene glycol, as acid and glycol respectively.