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
  • G03C1/85—Photosensitive materials characterised by the base or auxiliary layers characterised by antistatic additives or coatings

Definitions

• Backing materials for photographic layers are usually provided with an antistatic layer on the back in order to prevent them from becoming damaged during processing of the material, e.g. build up static charges on the surface during watering with photosensitive emulsions or after passing through the bath.
• the discharges would lead to exposure of the photographic layer, so that undesired markings in the image become visible.
• the static charge also causes the images to adhere to one another during sorting, so that further processing is disrupted.
• the back layer of the photographic material should also meet the following requirements: - Low dirt pick-up when the photographic material passes through roller transport developing machines, in which dirt films from the developer's oxidation products are easily deposited. - Highest possible abrasion resistance and resistance in alkaline developer solutions, which is important, for example, when the photographic material passes through processing machines equipped with rollers. - Good printability when printing with conventional printing inks as well as good lettering. - Good adhesive tape adhesion, since when the photographic material passes through modern development machines, the next roll in each case is glued to the previous roll and the adhesive adhesion must be ensured when the glue point passes through processing baths.
• hydrophobic components have the disadvantage of high dirt absorption and low antistatic activity
• hydrophilic components have low adhesive tape adhesion, poor printability and insufficient bath strength result.
• EP-AO 160 912 discloses a photographic material with a silver halide emulsion layer on one side of a polyolefin-coated paper support and an antistatic layer on the other side of the support, in which the antistatic layer contains a sodium magnesium silicate, a sodium polystyrene sulfonate and certain succinic acid half-esters.
• the conductivity in this combination is such that the desired antistatic properties are sufficient.
• the material also has a relative low dirt absorption.
• the object of the present invention is to provide a photographic material of the type mentioned at the beginning, the antistatic coated back of which at the same time has good properties with regard to all of the above five requirements.
• the antistatic layer contains a colloidal aluminum-modified silica, an alkali salt of an organic polyacid, for example sodium polystyrene sulfonate as a conductivity agent, an aqueous one Dispersion of copolymers of acrylic acid alkyl esters with a content of free carboxyl groups of 1 -10 mol% and free hydroxyl groups of 0 - 20 mol% as a binder, and a trifunctional aziridine as a crosslinking agent.
• an alkali salt of an organic polyacid for example sodium polystyrene sulfonate
• an aqueous one Dispersion of copolymers of acrylic acid alkyl esters with a content of free carboxyl groups of 1 -10 mol% and free hydroxyl groups of 0 - 20 mol% as a binder and a trifunctional aziridine as a crosslinking agent.
• crosslinking agents for plastic dispersions containing free carboxyl groups.
• this backside coating according to the invention shows both sufficient conductivity and thus good antistatic properties, low dirt absorption with regard to the mostly dark-colored oxidation products of developer solutions, good abrasion and water resistance when passing through acidic and alkaline development baths, good printability with commercially available printing inks and good writing properties as well as good adhesive tape adhesion even with chemical and mechanical stress.
• the sum of the polar groups does not exceed 25 mol% of the copolymer of acrylic acid esters.
• a terpolymer of styrene, C1-C4-alkyl acrylate and 10% methacrylic acid is provided as a binder.
• the effectiveness of the combination of the specific binder according to the invention and the crosslinking agent is increased by sodium magnesium silicate of the montmorillonite type additionally contained in the antistatic layer.
• the proportions of the components are based on the dry layer as follows: colloidal silica: 23 - 70% by weight Alkaline salt of polyacid: 3 - 30% by weight Polymer binder: 30 - 70% by weight Montmorillonite: 0 - 30 wt:% Aziridine: 2-18% by weight
• the layer application (dry) is 0.2 - 1.0 g / m2, in particular 0.2 - 0.5 g / m2.
• the support material for photographic layers according to the invention is produced in particular by slowly mixing the individual components in the sequence water-alcohol mixture, montmorillonite, colloidals, aluminum-modified silica, copolymer dispersion, alkali salt of organic polyacid, aziridine, the desired pH - Sets the value with ammonia solution, applies the casting solution thus obtained in the desired layer thickness and then dries.
• the antistatic properties are tested by measuring the surface resistance with an electrode according to DIN 53482.
• samples are printed with standard color ribbons.
• the samples were printed in a 30 sec commercial developer dipped and rinsed briefly with water. Then you apply finger friction to the printed back. It is checked whether the print is blurred or whether discoloration occurs due to the washing out of a color component of the printing ink.
• a print smeared after developer bath and friction is either due to poor adhesion of the print on the back of the photographic material or to low abrasion resistance of the back coating. The latter, i.e. damage due to abrasion of the back surface, can be seen when viewed against the light.
• the sample is provided with a commercially available adhesive tape (eg 3 M adhesive tape 8422) and this is fixed with a defined weight (8 kg roll). Then the pattern is cut into 1.5 cm wide strips and the adhesive tape is partially peeled off.
• the sample prepared in this way is clamped in a breaking load tester in which the adhesive tape is removed from the base at an angle of 180 ° at a speed of 20 cm / min. The force required to pull off is measured. Since the adhesive tape adhesion must be sufficient even under mechanical stress in developing solutions, a drop of water is placed on the boundary between the photographic material and the adhesive tape before the adhesive tape is peeled off.
• Table 1 below contains examples of compositions of mixtures for antistatic layers according to the invention. The associated test values are contained in Table 2.

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Publications (3)

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Citations (5)

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• 1987
  • 1987-01-06 DE DE19873700183 patent/DE3700183A1/de not_active Withdrawn
  • 1987-10-31 AT AT87116068T patent/ATE78938T1/de not_active IP Right Cessation
  • 1987-10-31 ES ES198787116068T patent/ES2033285T3/es not_active Expired - Lifetime
  • 1987-10-31 EP EP87116068A patent/EP0274017B1/fr not_active Expired - Lifetime
  • 1987-10-31 DE DE8787116068T patent/DE3780791D1/de not_active Expired - Lifetime
• 1988
  • 1988-01-05 JP JP63000165A patent/JPS63173044A/ja active Pending
• 1989
  • 1989-07-14 US US07/380,212 patent/US5104779A/en not_active Expired - Fee Related
• 1992
  • 1992-09-11 GR GR92300032T patent/GR920300032T1/el unknown
  • 1992-09-28 GR GR920402139T patent/GR3005814T3/el unknown

Patent Citations (5)

Non-Patent Citations (2)

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