Patent GB-575512-A (GB)
Title: Improvements in or relating to photographic materials
IPC: G03C1/76
Filed: 1944-02-03
Abstract: A photographic element comprises at least one layer containing a polymerized alkyl methacrylate resin containing free carboxyl groups, examples being protective, supercoating, colour filter, antihalation and stripping layers as well as separate layers for containing colour formers.  A methyl methacrylate resin of this kind is prepared by copolymerization of methyl methacrylate and methacrylic acid dissolved for example in methyl alcohol and benzene and heated in the presence of a catalyst, e.g. benzoyl peroxide.  Another method is the partial hydrolysis of a fully-esterified methyl methacrylate polymer by acid or alkali, e.g. by heating a solution of the polymer in cold sulphuric acid, the temperature and duration of heating determining the percentage of hydrolysis.  The higher the percentage of hydrolysis, the more the polymer is soluble and for layers containing colour formers which are not to be removed by a normal developer, a polymer having between 30 and 35 per cent hydrolysis is used.  Wet printing layers which have high-water resistance, but solubility in alkaline developers, require a polymer of 45-60 per cent hydrolysis. Antihalation and similar layers require a polymer of above 60 per cent hydrolysis.  Dyestuffs for filter or antihalation layers include Tartrazine, Auramine, Malachite Green, Acid Magenta, Aniline Blue, Rosaniline triphenyl-methane dyes containing carboxyl or sulphonic groups, e.g. fuchsone carboxylic acids, and styryl and di-and tri-phenylamine bases p  which react with the carboxyl groups of the polymer.  Colouration of the layers may also be by pigments, e.g. colloidal silver, silver sulphide, manganese dioxide and phthalocyanine pigment dyes.  The layers may contain as colour formers for yellow, diacetylamino - 1.2.4.5 - benzo - bis - thiazoles, e.g. difuroylacetamino-1.2.4.5-benzo-bis - thiazole and diacetoacetamino - 1.2.4.5 - benzo - bis - thiazole, 2 - hydroxy - 3 - naphthoyl - aminobenzoyl acetanilide, sodium stearoyl-amino - benzoyl - acetanilide - p - carboxylate, p - caproylamino - benzoyl - amino salicylic acid, furoylacet - p - amino - phenylamylether and dipicolinoylacet benzidide; for magenta, 1-(31-sulphophenyl)-3-(411-stearoyl-aminophenyl) - 3 - (411-dodecoylamino-phenyl)-5-pyrazolone, 4.41-bis - (311 - methyl - pyrazolonyl - 111) - diphenyl, 4.41-methylene-bis-(m-stearoyl-aminophenyl) -methyl-pyrazolone and 4.41-o-sulpho-benzylidene - (phenyl - methyl - pyrazolone); for blue-green, 4.41 - di - (1 - hydroxy - 2 - naphthoylamino) diphenyl, 1 - hydroxy - 2 - carboxy - 5 - dodecoylamino naphthalene, 1-N-stearoyl-4-N-(11-oxy-21 - naphthoyl) - phenylenediamine sodium sulphonate, resorcinol mono-n-dodecyl ether, the product of p-hydroxybenzoic acid and formaldehyde and the product of polyvinyl alcohol and salicylaldehyde.  The resins may be cast in layers from solution in acetone or aqueous acetone which includes plasticisers, e.g. butyl tartrate or tricresyl phosphate and wetting agents, and may be used in conjunction with other colloids or added to gelatino-silver halide emulsions. Higher alkyl methacrylate resins may be used.  Specifications 512,542, 535,341, 542,904, 543,290, 550,775, [Group XX], 551,117 and 14656/39, as open to inspection under Sect. 91, are referred to.