Classifications

• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
  • G03C1/00—Photosensitive materials
  • G03C1/76—Photosensitive materials characterised by the base or auxiliary layers
  • G03C1/91—Photosensitive materials characterised by the base or auxiliary layers characterised by subbing layers or subbing means
  • G03C1/93—Macromolecular substances therefor

Definitions

• the present invention relates to coated film bases suitable for coating with light-sensitive photographic emulsions and to processes for their production, and also to light-sensitive photographic films derived from such coated film bases and to processes for their production.
• the adhesion of light-sensitive photographic emulsions applied directly to the surface of a plastics support film is generally inadequate to withstand the conditions of handling and treatment to which photographic films are subjected.
• the subbing layers of typical conventional photographic films generally comprise, outwardly from the support film, a copolymeric subbing layer and a gelatinous subbing layer, a light-sensitive photographic emulsion such as a gelatinous emulsion containing a light-sensitive silver halide being adhered to the gelatinous subbing layer.
• a coated film base suitable for coating with a light-sensitive photographic emulsion comprises a self-supporting plastics film and a copolymeric subbing layer applied to at least one surface thereof, said copolymeric subbing layer comprising a copolymer prepared from a comonomer mixture comprising 35 to 55 mole % acrylic acid or a lower alkyl ester thereof in which the alkyl group comprises up to 8 carbon atoms, 35 to 55 mole % methacrylic acid or a lower alkyl ester thereof in which the alkyl group comprises up to 8 carbon atoms, and 1 to 15 mole % of itaconic acid, a half ester of itaconic acid or itaconic anhydride, and said copolymeric subbing layer having a dry coat weight in the range 0.05 to 3.00 mg/ dm 2 .
• the invention further relates to a light-sensitive photographic film comprising said coated film base and a light-sensitive photographic emulsion bonded directly to the copolymeric subbing layer of the coated film base.
• a process for the production of a coated film base suitable for coating with a light-sensitive photographic emulsion comprises coating at least one surface of a self-supporting plastics film with a subbing composition comprising an aqueous dispersion or a solution in an organic solvent of a copolymer prepared from a comonomer mixture comprising 35 to 55 mole % acrylic acid or a lower alkyl ester thereof in which the alkyl group comprises up to 8 carbon atoms, 35 to 55 mole % methacrylic acid or a lower alkyl ester thereof in which the alkyl group comprises up to 8 carbon atoms, and 1 to 15 mole % of itaconic acid, a half ester of itaconic acid or itaconic anhydride, and causing or allowing the coating to dry to a coat weight in the range 0.05 to 3.00 mg/dm 2 .
• Another aspect of the invention relates to a process for the production of a light-sensitive photographic film in which the copolymeric subbing layer of a coated film base produced by such a process is coated directly with a light-sensitive photographic emulsion.
• the self-supporting plastics film may consist of a cellulose ester such as cellulose triacetate or any suitable thermoplastics film, such as films of polysulphones, polystyrene and linear polyesters which may be obtained by condensing one or more dicarboxylic acids or their lower alky diesters, e.g.
• terephthalic acid isophthalic, phthalic, 2,5-, 2,6- and 2,7-naphthalene dicarboxylic acid, succinic acid, sebacic acid, adipic acid, azelaic acid, diphenyl dicarboxylic acid, and hexahydroterephthalic acid or bis-p-carboxyl phenoxy ethane, optionally with a monocarboxylic acid, such as pivalic acid, with one or more glycols, e.g. ethylene glycol, 1,3-propanediol, 1,4-butanediol, neopentyl glycol and 1,4-cyclohexanedimethanol.
• glycols e.g. ethylene glycol, 1,3-propanediol, 1,4-butanediol, neopentyl glycol and 1,4-cyclohexanedimethanol.
• Biaxially oriented and heat-set films of polyethylene terephthalate are particularly useful for the production of the photographic films according to this invention.
• Such self-supporting thermoplastics films may be transparent and light- transmitting, optionally including photographically inert dyestuffs, e.g. blue dyestuffs for X-ray films, or may be rendered opaque by the addition of additives, such as pigments and fillers, and may in particular have a white and paper-like texture which may be achieved by the addition of suitable fillers and/or by voiding.
• the white and paper-like films may be used as bases for photogreaphio prints.
• Films suitable for use in "instant" photography may be pigmented black with carbon black particles.
• the lower alkyl esters of acrylic and methacrylic acid as comonomers of the subbing copolymer may comprise the methyl, ethyl, propyl, isopropyl, butyl, pentyl, hexyl, heptyl, n-octyl and 2-ethylhexyl esters, the preferred esters being ethyl acrylate and methyl methacrylate.
• Itaconic acid is particularly effective as the third comonomer.
• Half esters of itaconic acid wherein one carboxylic acid group is esterified are also effective comonomers. It has been found that the use of itaconic acid, a half ester of itaconic acid or itaconic anhydride as comonomers in the subbing copolymer is effective not only in providing the desired adhesive properties of the photographic emulsion applied thereto but also in enhancing the wetting of the plastics film during the application of the subbing composition.
• the subbing copolymer may if desired, be derived from four or more comonomers, the additional comonomers being employed to modify such properties as dry adhesion and being present in the copolymer in an amount comprising up to 8 mole %.
• additional comonomers include acrylamide, methacrylamide, N-methylol acrylamide, N-ethanol acrylamide, N-propanolacrylamide, N-methylol methacrylamide, N-ethanol methacrylamide, N-methyl acrylamide, N-tertiary-butylacrylamide, nitriles, e.g. acrylonitrile, halo-substituted acrylonitrile and methacrylonitrile, and amines, e.g. dimethylaminoethylmethacrylate.
• the subbing copolymer may be prepared by conventional emulsion polymerisation techniques in water in the presence of a suitable emulsifying agent or a mixture of emulsifying agents.
• the total amount of emulsifying agent can influence the adhesion of photographic emulsions to the copolymeric subbing layer and it is therefore preferred to employ up to 5% by weight of emulsifying agent based on the total weight of the comonomers and preferably about 4% by weight.
• Anionic emulsifying agents such as unbranched sodium dodecyl benzene sulphonate, which is available commercially as 'Nansa' 11C6 provide particularly good adhesions to photographic emulsions which may if desired be used in admixture with other emulsifying agents.
• copolymeric subbing composition Conventional additives such as adhesion promoters, slip and anti-static agents may be included in the copolymeric subbing composition in small amounts, e.g. not exceeding 10% by weight based upon the weight of the subbing copolymer, since larger amounts may adversely affect the adhesion of photographic emulsions.
• the subbing composition may be applied to the film before, during or after the stretching process employed to achieve orientation.
• a convenient procedure is to coat the film between the two stretching operations which are applied in mutually perpendicular directions to orient the film, particularly as this enhances the adhesion between the film and the subbing layer.
• the procedure for applying the subbing composition may be any of the known coating techniques, such as dip coating, bead coating, reverse roller coating, air knife, direct gravure or slot coating and the composition may be applied as an aqueous latex or solution or as a solution in an organic solvent.
• the pH of the subbing composition should preferably be in the range 2.0 to 5.0 and most preferably 2.5 to 3.0. Whilst coating quality is better with higher pHs, e.g. up to 7, it has been found that a satisfactory combination of adhesion and coating quality is obtained in the range 2.5 to 3.0.
• the subbing copolymer should comprise from 2 to 10% by weight and particularly about 5% by weight of the subbing composition since compositions of such concentration dry slowly and provide subbing layers of uniform coating quality having particularly satisfactory adhesions to photographic emulsions.
• the dried copolymeric subbing layer has a coat weight in the range 0.05 to 3.00 mg/dm 2 and most preferably G.5 to 1.00 mq/dm 2 for optimum adhesion to photographic emulsions.
• Such coat weights may be accomplished by appropriate modifications to the concentration of the subbing composition and/or the conditions of coating.
• copolymeric subbing layers applied according to this invention to linear polyester films such as polyethylene terephthalate films are such that the film base, i.e. the polyester film carrying the copolymeric subbing layer but not the light-sensitive photographic emulsion, is suitable for recycling through the film- forming extruder and stretching equipment.
• Any suitable light-sensitive photographic emulsion such as a conventional gelatinous silver halide emulsion, may be applied by conventional techniques directly to the subbing layer.
• Alternative light-sensitive emulsions based upon binding resins other than gelatin, e.g. those binding resins described in United States patent 4 033 772, may also be applied with good adhesion to the subbing copolymer layers of this invention.
• Such emulsions may contain any of the conventional additives. It has been found that light-sensitive photographic emulsions bond with good adhesion after direct application to the surface modified layer.
• Light-sensitive photographic emulsions such as conventional gelatinous silver halide X-ray and graphic arts emulsions, adhere to the copolymeric subbing layers with good adhesions before and after accelerated ageing by incubation when evaluated by the tests described below.
• subbing compositions for each Example were prepared in batches by conventional emulsion polymerisation in water, the comonomers and other polymerisation ingredients and the quantities employed being shown in Tables 1 to 3 together with the amount of unpolymerised acid in % by weight based on the weight of the copolymer and the pH of the latices.
• a polyethylene terephthalate film was melt extruded and quenched to the amorphous state on a cooled rotating drum. The resulting film was stretched in the direction of extrusion to about 3.0 times its original length. It was then coated on one side with the aqueous subbing composition described in each of the Examples and passed into a stenter oven where the coating was dried.
• the coating composition which was applied by a roller coating technique, contained about 5% by weight of the subbing copolymer based on the total weight of the composition.
• the dried coated film was then stretched sideways about 3.0 times its original width and finally heat set at a temperature of about 220°C.
• the resulting. films had an overall thickness of about 100 microns and the dry coat weights of the applied subbing are shown in Tables 1 to 3.
• a conventional aqueous gelatinous silver halide emulsion was applied directly to the subbing layers and tested for dry and wet adhesions by the procedures described above, the adhesions also being shown in Tables 1 to 3.
• the measured adhesions between the emulsion layers and the subbing .layers are sufficient to resist the conditions of handling and treatment, including wet processing, to which photographic films are normally subjected.
• subbing layers described in the above Examples provided satisfactory adhesions to other photographic emulsions including modified X-ray emulsions.

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• Physics & Mathematics (AREA)
• Spectroscopy & Molecular Physics (AREA)
• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• General Physics & Mathematics (AREA)
• Coating Of Shaped Articles Made Of Macromolecular Substances (AREA)

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Citations (11)

• 1978
  • 1978-09-18 DE DE7878300394T patent/DE2861457D1/de not_active Expired
  • 1978-09-18 EP EP19780300394 patent/EP0001484B1/fr not_active Expired

Patent Citations (11)

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