GB842062A - Improvements in photographic silver halide emulsions - Google Patents

Abstract

842,062. Photographic silver halide emulsions. DU PONT DE NEMOURS & CO., E.1. July 14, 1958 [July 16, 1957], No. 22559/58. Class 98(2) The emulsions contain non-optical sensitising agents having a molecular weight of at least 282 and at least two oxyalkylene radicals of 2 to 4 carbon atoms, i.e. polyethylene oxide type compounds and condensation products thereof with acids, alcohols and amines; and, as antifoggants, operating under adverse conditions of storage without important reduction of speed or contrast especially for low intensity exposing illumination, bis-phenols.. Various types of silver halide emulsions are referred to, particularly high speed iodobromide, and the emulsions may contain also gold, sulphur or optical sensitising agents. Gelatin is the preferred binding agent but others are specified. The polyoxyethylene sensitisers for which foreign Specifications are provided as references are preferably added to the emulsions after digestion, and the bis-phenols for preparation of which Specifications 621,004, 622,977 and other references are quoted and for which a structural formula is presented may be added after that; at the same time, however, further antifoggants such as benzotriazole, nitrobenzamidazole, 1-phenyl-5-mercaptotetrazole and benzothiazole may be added as well. Twelve specific Examples describe use of the above mentioned iodobromide emulsion sensitised with sulphur and gold compounds, which are usually divided into three portions (1) control, (2) sensitised additionally either with a polyethylene oxide oleyl alcohol condensate known under the Registered Trade Mark "Emulphor" or else a polyethylene oxide known under the trade name "Carbowax" and (3) so sensitised but containing also bis-phenols as described below; and speed, gamma and fog data are quoted for these after X-ray exposure at high and at low intensity levels and processing with a specified developer, and after room and tropical ageing as well as for the freshly made material. The bis-phenols for the Examples are (I) 2,21 - methylene - bis (4 - methyl - 6 - tert - butylphenol), (II) 4,41 - methylene - bis - (2 - - tert - butyl - 6 - methylphenol), (III) 2,21 - methylene - bis - (4 - - tert - butyl - 6 - methylphenol), (IV) 2,21 - methylene - bis - (4 - ethyl - 6 - tert - butylphenol), (V) 2,2<1> - methylene - bis - (3,4 - dimethyl- 6 - n-octylphenol), (VI) 2,21 - butylidene bis - (4,6 - di - tert - butylphenol), (VII) 2,21 - ethylidene bis - (4 - methyl - 6 - tertoctylphenol), (VIII) 4,4<1>-isopropylidene-bis-phenol (IX) 2,21 - n - butylidene - bis - (6 - cyclohexyl - 4-ethylphenol), (X) 2,2<1>- n - butylidene - bis - (4 - isopropylphenol), (XI) 2,2<1>-n-butylidene-bis-(4-methylphenol) and (XII) bis - (2 - methyl - 4 - hydroxy - 5 - tert - butylphenyl) sulphide. Numerous other bis-phenols are referred to.