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
  • G03C1/805—Photosensitive materials characterised by the base or auxiliary layers characterised by stripping layers or stripping means

Definitions

• the light-sensitive layer to be hardened image-wise is a gelatin bichromate layer.
• Such light-sensitive material involves, however, many disadvantages including a poor stability and necessitates long exposure times. Moreover, the obtained results are rather uncertain.
• a photographic stripping film the light-sensitive layer of which is a non-hardened gelatino-silver halide emulsion layer, does not present such disadvantages.
• these photographic stripping films are mostly stripping films comprising a light-sensitive, non hardened gelatino-silver halide emulsion layer coated on a hydrophobic flexible membrane, which in its turn is releasably applied to a hydrophobic flexible backing or support.
• the flexible support assures the dimensional stability during the exposure and the tanning development of the gelatino-silver halide emulsion layer. After pressing the tanning developed silver halide emulsion layer against the surface to be etched, the flexible support is removed. During and after this treatment, the hydrophobic membrane protects the tanning developed silver halide emulsion layer against deformation or tearing.
• the flexible support can easily be remove-d by stripping off, whereas the removal of the hydrophobic membrane, however, is a delicate operation which can easily lead to failures.
• the process according to said British patent specification causes easily failures, as during the tanning development, a local hardening of the gelatin layer, the so-called contact tanning, can occur under the most exposed parts of the silver halide emulsion layer by diffusing oxidation products of the used developer. Hence, the removal of the hydrophobic membrane on these areas is very diflicult to achieve.
• a gelatin intermediate layer having a greater thickness can be applied, but the dimensional stability of the film is hereby decreased correspondingly.
• plasticizers are hydrophobic, residual parts of these substances can deposit, after the removal of the membrane, onto the most hardened tanning developed parts which are thus made less hydrophilic, whereby the penetration of the aqueous etching solution is locally decreased, so that a non-uniform etching may arise.
• Hydrophilic colloids which cannot be hardened with aldehydes or quinones and the physical properties of which are very well suitable for the obtention of the described layer, can be prepared by carrying out substitution reactions on the amino groups of gelatin as described in the Belgian Patent specifications 593,710 and 608,566.
• Particularly suitable compounds are the reaction products of gelatin and bromoacetic acid, pyromellitic dianhydride, p-carboxybenzly bromide, trirnellitic anhydride and o-methylisourea respectively.
• Some of the suitable hydrophilic colloids are even soluble in water of 25 C.
• the thin non-hardenable layer according to the present invention is mostly applied from a solution of at least one of the non-hardenable compounds in suitable solvents or mixtures of solvents e.g. in water, in a mixture of water and a lower aliphatic alcohol occasionally containing alkaline substances etc.
• suitable solvents or mixtures of solvents e.g. in water, in a mixture of water and a lower aliphatic alcohol occasionally containing alkaline substances etc.
• other substances can occasionally be incorporated such as plasticizers, stabilizers, antihalation dyes, etc.
• This solution is spread onto the hydrophobic membrane to which a subbing layer has been applied previously.
• the coating and drying temperatures are of no importance.
• the thickness of the thin layer is kept very small (e.g. so that after drying the thickness is less than 4,11. and preferably varies from 0.3 to 1.5a).
• the influence of such a thin layer on the dimensional stability may be neglected. Indeed, for a given support the dimensional stability is determined by the forces which act in the back layers and in the front layers of the support, since these forces can occasionally cause a deformation of the support.
• the hydrophobic support of a photographic stripping film according to the present invention can be manufactured from plastics such as cellulose diacetate, cellulose acetobutyrate, cellulose nitrate, cellulose triacetate, poly(ethylene terephthalate), poly(carbonate), etc. and its thickness amounts mostly from 50 to 200 1..
• a suitable stripping layer may be composed of cellulose nitrate (from 6 to 9 parts) and ethyl cellulose (from 4 to 1 parts) if the [hydrophobic backing is made from a cellulose ester (such stripping layer is described in the US. patent specification 2,638,417).
• the hydrophobic support is made from poly(ethylene terephthalate)
• such a suitable stripping layer can be composed of a copolymerization product of a diolefine and acrylonitrile or methacrylonitrile.
• Appropriate layer-forming components for the manufacture of the hydrophobic flexible membrane of a photographic stripping film according to the present invention are plastics which are soluble in organic solvents such as cellulose nitrate, cellulose triacetate, cellulose propionate, cellulose acetobutyrate, cellulose acetopropionate, cellulose diacetate, a mixture of ethyl cellulose and cellulose nitrate, other single or mixed esters of carboxylic acids and cellulose, poly(amides), poly(carbonates), poly(esters), poly(vinyl chloride), poly(vinyl esters) and poly(vinyl acetals).
• organic solvents such as cellulose nitrate, cellulose triacetate, cellulose propionate, cellulose acetobutyrate, cellulose acetopropionate, cellulose diacetate, a mixture of ethyl cellulose and cellulose nitrate, other single or mixed esters of carboxylic acids and cellulose, poly(amides), poly(carbon
• All types of emulsions the binding agent of which mainly consists of a hydrophylic colloid which is hardenable with aldehydes or quinones and which is soluble in water of 30-40 C. when not hardened, may be used for preparing the light-sensitive silver halide emulsion layer.
• a photographic stripping film according to the present invention can still comprise other layers such as back layers, an anti-halation layer, a protective covering layer, etc.
• the manufacture of the etch resists from-a photographic stripping film according to the invention can also be carriedout in different ways, although it is generally done as follows: image-wise exposure through a screen, tanning development, pressing against the surface to be etched, removal of the hydrophobic backing, removal of the flexible membrane e.g. according to a process as described in the French patent specification 1,281,283, washing away the unhardened parts and finally drying the obtained etching resist.
• EXAMPLE 1 (a) Composition of the photographic stripping film Cellulose nitrate g 8 Ethylcellulose g 4 Methanol cm. 700 Acetone cm. 250 n-butanol cm. O
• This solution is coated in such a way that after drying a layer is obtained of 14 g./sq. m.
• a subbing layer which is applied from the following coating composition, so that 1 1. covers 45 sq. m.:
• the photogravure film is pressed with the emulsion side onto the wetted copper roller to be etched. After 1 minute the hydrophobic support is removed by stripping off.
• the flexible membrane is contacted for 15 see. with the following mixture:
• the etching of the copper surface is carried out with aqueous ferric chloride (42 B.) according to the hardening pattern of the obtained etch resist.
• Example 1 is repeated with a suchlike material, but of which the thin layer contains a non-hardenable hydrophilic colloid and is coated from the following composition:
• This composition is coated in such a way that after drying 1.2 g. of non-hardenable colloid is present per sq. m. of material.
• EXAMPLE 3 566 g 25 Water cm. 200 Ammonium hydroxide cm. 15 4% aqueous sodium hydroxide cm. 60 Methanol cm. 660
• This composition is coated in such a way, that after drying 1 g. of non-hardenable colloid is present per sq. m. of material.
• Example 1 is repeated with a suchlike material, but of which the thin layer contains a non-hardenable hydrophilic colloid and is coated from the following composition: Reaction product of gelatin and trimellitic anhydride,
• This composition is coated in such a way, that after drying 1 g. of non-hardenable colloid is present per sq. m. of material.
• Example 1 is repeated with a suchlike material, but of which the thin layer contains a non-hardenable hydrophilic colloid and is coated from the following com position:
• This composition is coated in such a way, that after drying, 1 g. of non-hardenable colloid is present per sq. m. of material.
• Example 1 is repeated with a suchlike material, but instead of the layers 1 and 2 the stripping film used for this example comprises the following layers:
• a polyethylene terephthalate support of a thickness of 100a which is provided at its rear side with usual photographic subbing and antihalation layers.
• a photographic stripping film comprising in the indicated sequence (1) a hydrophobic flexible support, (2) a stripping layer, (3) a hydrophobic flexible membrane which is soluble in organic solvents, (4) a subbing layer,
• a light-sensitive silver halide emulsion layer the binding agent of which predominantly consists of a hydrophilic colloid which is hardenable with a hardening agent selected from the group consisting of aldehydes and quinones and which in unhardened state is soluble in water of 3040 C.
• a photographic stripping film comprising in the indicated sequence (1) a hydrophobic 'flexible support, (2) a stripping layer, (3) a hydrophobic flexible membrane which is soluble in organic solvents, (4) a subbing layer, (5) a thin layer of at most 4 thickness predominantly consisting of gelatin having the amino groups thereof substituted by reaction with a member of the group consisting of compounds having at least one acid anhydride group, at lea-st one active halogen atom, and lower alkylisourea and which is soluble in water of Sil -40 C., and ('6) a light-sensitive silver halide emulsion layer, the binding agent of which predominantly consists of a hydrophilic colloid which is hardenable with a hardening agent selected from the group consisting of aldehydes and quinones and which in unhardened state is soluble in water of 30-40 C.
• a photographic stripping film comprising in the indicated sequence (1) a hydrophobic flexible support, (2)

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Laminated Bodies (AREA)
• Separation Using Semi-Permeable Membranes (AREA)

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Citations (7)

• 0
  • NL NL273549D patent/NL273549A/xx unknown
  • BE BE627076D patent/BE627076A/xx unknown
• 1963
  • 1963-01-08 US US250028A patent/US3282698A/en not_active Expired - Lifetime
  • 1963-01-12 DE DE19631447673 patent/DE1447673A1/de active Pending
  • 1963-01-14 CH CH40063A patent/CH426476A/de unknown
  • 1963-01-15 GB GB1866/63A patent/GB1035441A/en not_active Expired

Patent Citations (7)

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