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
  • G03C3/00—Packages of films for inserting into cameras, e.g. roll-films, film-packs; Wrapping materials for light-sensitive plates, films or papers, e.g. materials characterised by the use of special dyes, printing inks, adhesives
  • G03C3/02—Photographic roll-films with paper strips

Definitions

• the invention relates to a light-protection paper which is intended to protect light-sensitive film material from the action of light and to ensure the problem-free transport of the film material in the camera.
• Sunscreen papers generally consist of an opaque, usually colored paper base, which is provided on one side with markings or characters (the so-called signature printing).
• the protective papers can be coated in order to improve the light security, to prevent photographic effects of the paper or the printing inks used for the signature printing on the film material or to prevent the paper from sticking to the photographic light-sensitive layers of the film or the gelatin-containing backing layers .
• a light-sealing protective strip for roll films known from DE-B-1 036 050 is formed from two thin films which are glued to one another, one of which is made of opaque and the other of transparent plastic. Between the two foils or on the inside of one of the two foils there is a pigment layer and the so-called signature printing. The foils are glued together using an adhesive or thermoplastic. The opaque film can also be a pigmented paper. The production of such protective strips is relatively complicated because of the adhesive technology required.
• CH-A-498423 proposes, among other things, an aqueous dispersion of polystyrene to coat a light-proof paper. However, it is difficult to produce sufficient adhesion to the support under customary coating conditions.
• a light protection paper which consists of a kraft paper coated by extrusion with carbon black containing soot.
• the polyethylene layer produced in this way contributes at least 20 f.Lm to the thickness of the light protection paper.
• US-H-871 004 describes a light-protection paper which contains a layer blackened with carbon black and consisting of styrene-butadiene copolymer which is coated with a layer of carbon black and polyethylene or polypropylene on a paper base.
• the top layer can be applied to the underlying polymer layer, e.g. B. by melt extrusion or from an aqueous dispersion.
• the lower layer is exposed to corona radiation before the coating in order to improve the adhesion.
• the disadvantages already described are associated with the production of the top layer by melt extrusion.
• the application of the top layer from an aqueous dispersion requires the use of corona radiation, that is to say a considerable additional technical outlay.
• Light-protection papers which are produced by coating a backing paper with a mixture of an ethylene-vinyl acetate copolymer and carbon black in toluene are described in DE-A-1 903378. Sunscreen papers equipped in this way, however, show insufficient suitability for the tropics. They have a pronounced tendency to stick at higher air humidities.
• the object of the invention is to develop a light-protection paper which can be produced in a technically simple and economical manner and which, with the smallest possible overall thickness, has the light security and the mechanical properties which are required for a protective paper for photographic roll films.
• a light-protection paper which contains a paper support, the surface of which is provided on one or both sides with a layer formed from a polyolefin or a polyolefin mixture, and which is characterized in that the layer is dried by the dispersion of one or more polyolefins is formed in water or an organic liquid.
• Suitable layer-forming polyolefins are based on C 2 -C 4 alkenes. Examples are polyethylene, polypropylene, polybutylene or polyisobutylene. Polyethylene and polypropylene are preferred.
• the polyolefins are applied as a dispersion in water or in an organic liquid to the surface of an optionally colored or blackened paper, which can also be provided with markings and characters, and the layer is dried.
• Dispersions of the polyolefins mentioned in water or organic liquids which are suitable for finishing the light-protection papers of the invention are commercially available.
• Aqueous polyolefin dispersions are offered with solids contents of approximately 40% by weight.
• the size of the disperse The particle size is between 0.1 and 0.2 ⁇ m.
• the dispersions can be diluted with water and mixed with one another.
• Polyolefin dispersions in organic liquids are also commercially available. It is e.g. B. to dispersions of polyethylene in xylene, ethanol, butanol, butyl glycol or similar organic solvents.
• the particle sizes range from 0.5 to 10 ⁇ m, the solids content is between 20 and 25% by weight.
• polyolefin dispersions can be produced in both water and organic liquids.
• Suitable dispersions can e.g. B. can be obtained by emulsion polymerization of olefins or by dispersing corresponding micronized polymers in the appropriate medium.
• dispersions in organic media can be used advantageously under certain technical conditions, aqueous dispersions are nevertheless preferred for economic and ecological reasons.
• the amount of dispersions or polyolefins to be applied can be adapted to the respective requirements.
• the amount of dry substance applied can range between 1 g / m 2 and 20 g / m 2 . Application quantities between 3 and 10 g / m 2 are preferred.
• the thickness of the dry coating should be 1-20 ⁇ m, preferably 3-10 kt m.
• pigments, dyes, matting agents or other substances can be applied to the paper base with which the optical or mechanical properties of the light-protection papers can be influenced in the desired manner.
• the additives should not exceed a proportion of about 20-30% by weight, based on the dry amount of polymer applied.
• the light protection papers of the invention can be provided on one or both sides with the polyolefin layer. All common methods are suitable for applying the dispersions, e.g. B. immersion process, roll application process with smooth or anilox rolls, air knife or squeegee.
• the base paper can be coated immediately or only after printing. In the first case, the job is most conveniently already carried out by the paper manufacturer on the size press or coating machine. In the second case, it is most economical to carry out the coating in one step using the signature printing.
• the layers can be dried by known methods, e.g. B. with warm air, IR radiators, heating rollers or the like.
• So-called kraft papers are particularly suitable as paper supports. Of course, there are also other types of paper that have the required physical strength; suitable.
• the raw paper weights are 40 to 100 g / m 2 .
• Such base papers have the mechanical strength and elasticity required for the intended purpose.
• the paper may contain carbon black or be blackened on one side to provide the required light safety.
• the paper used can also be printed in a conventional manner with characters or picture numbers.
• the light-protection papers equipped with polyolefin layers in accordance with the invention prove surprisingly superior to the known light-protection papers with extruded or laminated-on polyolefin layers.
• the polyolefin layers can be kept considerably thinner so that correspondingly higher mechanical strengths can be achieved with the same total thickness of the light-protection paper, which is essentially due to the quality and thickness of the paper.
• the light-protection papers of the invention are distinguished by the simplicity and economy of their production and by their excellent suitability for the tropics.
• polyolefin dispersions generally contain additions of dispersants which generally have no anti-adhesive properties. It can therefore be assumed that these dispersants diffuse largely into the paper and that only residues are left on the surface of the layer after the drying process has been completed.
• the thickness of the papers is measured in accordance with DIN 53111 using a measuring device which has a measuring area of 2 cm 2 with a contact pressure of 1 kp / cm 2 (9.8 N / cm 2 ).
• the mechanical strength is tested on a commercial tearing machine.
• the width of the test strip is 15 mm, the clamping length is 180 mm.
• the test climate is 23 ° C, 50% relative humidity.
• the samples are adjusted for 24 hours before the test.
• the determined breaking load serves directly as a measure of the mechanical strength.
• a 40% by weight aqueous polyethylene dispersion was applied at 30 m / min to a raw paper corresponding to sample A in the roller application process and dried with warm air at 60.degree.
• the application unit was set so that the dry layer application was 10 g / m 2 .
• the thickness of the coated paper was then 100 microns, the coating of about 100 I Lm. Tested were mechanical strength and tendency to stick, the latter in such a way that the rear side of the roll film is in contact with the coated side of the paper.
• Soot-filled uncoated kraft paper 95 ⁇ m thick.
• a 20% by weight aqueous polyethylene dispersion was applied to raw paper corresponding to sample A at 25 m / min in the immersion process with subsequent air brush blowing.
• the air brush was adjusted so that the amount of solids applied was 6 g / m 2 and the layer was about 5 ⁇ m thick.
• the total thickness of the coated paper was then 100 microns.
• a 75 ⁇ m thick soot-filled kraft paper was coated with a 25 ⁇ m thick polyethylene layer using the extrusion process.
• the amount applied was set to a dry layer thickness of 5 ⁇ m.
• the following results were found for a total thickness of 100 ⁇ m of the paper coated in this way:
• the example shows that an addition of pigment in the polyethylene layer does not impair the mechanical strength of the light-protection paper according to the invention and does not increase the tendency to stick.
• a 15% by weight polyethylene dispersion was applied to the printed side of a paper corresponding to sample A in a roller application process in such a way that the coating was about 3 g / m 2 and about 3 ⁇ m thick.
• the test was carried out as for sample A.
• a light protection paper according to the invention achieves higher mechanical strength than paper with an extruded polyethylene layer with the same overall thickness and the same suitability for the tropics.
• Example 2 was repeated with the proviso that a polyethylene dispersion in organic medium was used.
• Uncoated soot-filled kraft paper 95 ⁇ m thick.
• Kraft paper according to sample A coated on one side with a 20% by weight polyethylene dispersion in n-butanol, application amount 6 g / m 2 , layer thickness 5 ⁇ m.
• Soot-filled kraft paper 75 ⁇ m thick, coated on one side with polyethylene using an extrusion process, layer thickness 25 ⁇ m.
• Example 2 was repeated with the modification that a 20% aqueous polypropylene dispersion was used.
• Uncoated soot-filled kraft paper 95 ⁇ m thick.
• Kraft paper according to sample A coated on one side with a 20% by weight aqueous polypropylene dispersion, application amount 6 g / m 2 , layer thickness 5 wm.
• Soot-filled kraft paper 75 wm thick, coated on one side with polypropylene in the extrusion process, layer thickness 25 ⁇ m.

Landscapes

• Engineering & Computer Science (AREA)
• Microelectronics & Electronic Packaging (AREA)
• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Paper (AREA)
• Laminated Bodies (AREA)
• Silver Salt Photography Or Processing Solution Therefor (AREA)
• Manufacture Of Macromolecular Shaped Articles (AREA)

Applications Claiming Priority (2)

Publications (3)

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ID=6136453

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• 1981
  • 1981-07-09 DE DE19813127043 patent/DE3127043A1/de not_active Withdrawn
• 1982
  • 1982-07-01 DE DE8282105869T patent/DE3267901D1/de not_active Expired
  • 1982-07-01 EP EP82105869A patent/EP0069927B1/de not_active Expired
  • 1982-07-07 CA CA000406765A patent/CA1194737A/en not_active Expired
  • 1982-07-08 JP JP57117907A patent/JPS5817434A/ja active Pending

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