Patent GB-522161-A (GB)
Title: Improvements in photographic films
IPC: C08G73/00
Filed: 1938-12-02
Abstract: 522,161. Coated films.. TRIGGS, W. W. (Du Pont de Nemours & Co., E. I.). Dec. 2, 1938, No. 35137. [Class 140] [Also in Groups IV and XX] The film base of a photographic film is composed wholly or in part of a synthetic linear polymer containing amide or thioamide groups as an integral part of the main chain of atoms in the polymer. The light-sensitive layer or layers may be gelatino-silver halide emulsion. The polymer may be a simple polyamide, or an interpolyamide, ester-amide interpolymer, polyurea, polycarbamate, or corresponding sulphur analogues. Polyamides obtained from polymerizable monoaminomonocarboxylic acids or their amide-forming derivatives, or those obtained by reaction of diamines with dicarboxylic acids or amide-forming derivatives thereof may be used. The polyamide film base may be subjected to cold drawing or cold rolling. The film base may be formed from a solution or directly from the molten polymer and it may be tempered by rapid chilling. It may be subjected to heating under tension, if desired in presence of a mild swelling agent, e.g., water, steam, or alcohol, and then to cooling while still under tension. It may contain plasticisers, e.g., o-hydroxydiphenyl, diphenylol propane, diamyl phenol, or N-ethylp-toluene sulphonamide, or softening agents. The film-base may be coated on one or both sides with film-forming substances of high molecular weight, e.g., cellulose esters or ethers, polyvinyl compounds, polyhydric alcohol - polybasic acid resins. The polyamide used may be poly-tetramethylene suberamide, polyhexamethylene adipamide, poly-decamethylene p-phenylene diacetamide, poly-p-xylylene sebacamide, or a polyamide obtained by polymerization of 6-aminocaproic, 9-amino-nonanoic, acid, or 11-aminoundecanoic acid. The light-sensitive layer may contain bichromated hydrophilic colloids, e.g., albumen, gelatin, gum arabic, or glue with ammonium bichromate. The light-sensitive compound may be contained in mixtures of reversible protein colloids and water dispersible cellulose derivatives such as cellulose diglycollate, sodium cellulose glycollate, water-soluble synthetic resins and gums such as polyvinyl alcohol and gum arabic. The light-sensitive layers may include iron salts or diazonium compounds and coupling components. A plurality of lightsensitive layers may be arranged on one or both surfaces of the support as in the case of colour photography. The films may bear a photographically produced sound track. The support may be dyed or tinted and it may be provided with an antistatic, anti-halation, or removable opaque layer. The linear polymer may form a surface coating on a cellulose nitrate or other film. Splicing of the film may be effected by application of solvents and pressure, or by application of heat and pressure. The use of thin films of polyamides facilitates operations of stripping emulsion films and papers. Thus, a paper strip coated with glue or casein is cemented to a similarly coated polyamide film. The film is rubbed and coated with gelatine-silver. halide emulsion. After exposure, developing, fixing, and colouring, the emulsion layer and its thin support is removed from the paper and transferred to a permanent support. In an 'example, polyhexamethylene adipamide is extruded into cold wa.ter to form a film, passed through cold rolls, and steamed under tension. It is then coated with gelatine-silver bromide emulsion containing sodium 3, 9-diethyl-tridecyl-6-sulphate, and dimethyl formamide. In another example, a polyamide film is provided with a sub-coat containing gelatine, 1,3-dichlorohydrin, phenol, methanol, acetone, and formaldehyde, and then with a silver halide emulsion. In another example an interpolymer from hexamethylene diamine adipate and 'decamethylene diamine sebacate is extruded to form a film. The film is subcoated with a cellulose acetate-gelatine solution and then coated with silver halide emulsion. Specifications 461,236, 461,237 and 491,111, [all in Group IV], and U.S.A. Specification 2,071,250, are referred to.