A method for the painting of on the rear or back of photographic plates or films disposed light well or court protection layers

摘要

To prevent the splitting-off of particles from an antihalation layer carried on the opposite side of the support to the sensitive emulsion the layer is coated with a natural or artificial resin containing in the molecule at least one hydroxyl or carboxyl group capable of forming a water-soluble alkali metal salt. Suitable artificial resins are the condensation products of formaldehyde, or a substance yielding formaldehyde or a phenol alcohol with a phenol, a phenylalkyl ether carboxylic acid, a phenylaryl ether carboxylic acid, an oxycarboxylic acid, an alkyloxycarboxylic acid or a phenoxy fatty acid. An artificial resin which has been treated with a halogenated fatty acid or a phenol or phenolcarboxylic acid condensed with an aliphatic, aromatic or heterocyclic aldehyde or thionyl chloride may also be used. A natural resin, such as colophony, which has been dissolved in an alkali, e.g. sodium carbonate, and precipitated with, for example, hydrochloric acid, is also applicable. In examples, an antihalation layer consisting of methyl blue in a layer of ammonium polyglucuronate is coated with a layer of an artificial resin formed from formaldehyde and phenoxyacetic acid or from phenol and acetaldehyde and an acetyl cellulose or nitrocellulose film provided with an antihalation layer of methyl blue is coated with a protective layer of colophony or of the condensation product of o-methoxy-benzoic acid and p-cresol-dialcohol. Specification 374,735 is referred to.