US1997745A - Process for the manufacture of photographic films and of carriers for the same - Google Patents

Description

Patented Apr. 16, 1935 UNITED STATES PROCESS FOR THE MANUFACTURE OF PHO- TOGRAPHIC FILMS AND OF CARRIERS FOB THE SAME Max Ranker, Duren/Rheinland, Germany No Drawing. Application August 20, 1931, Serial No. 558,419. In Germany August 24, 1929 10 Claims.

The object of the application is a process for the manufacture of a substitute for the expensive celluloid films hitherto generally used in photography.

There has already been suggested for photographic or kinematographic films a substitute, obtained through making transparent my usual paper by dipping it into resin or oil solutions, and then coating it with photographic emulsion. Substitute films manufactured in this way are sufiiciently transparent and show no granulation. They have the disadvantage, however, that in the water-or even more in alkali-developing baths used in photography they soften very much and to a great extent lose their transparency. Furthermore, they turn so yellow in the course of time that they can no longer be used in the manufacture of reproductions. Another drawback of the oil tracing-paper films is that the oil preparation has an unfortunate effect upon the photographic emulsions.

The applicant has found that these disadvantages may be completely removed and that films may be obtained capable of replacing in the most varied ways the expensive celluloid films, both on account of their transparency and of their durability. Such films may be obtained by using as a foundation a transparent or translucent parchment-substitute paper, especially Pergamyn paper, that is to say a grease-ground paper or a sharply satinized parchment-substitute paper, and by covering it on one or both sides with a coating of varnish, upon which is laid a photographically sensitive gelatine emulsion. For the preparation of the parchment-substitute paper used as a-foundation, cellulose varnishes are peculiarly suitable, e. g. those containing cellulose ester, cellulose ether, or a mixture of both in so- I lution. Films manufactured in this way are.

highly transparent, and possess likewise all the necessary durability.

In order to obtain a particularly firm fixing of the coating of cellulose varnish to the foundation, and to prevent a loosening of the same, the foundation may then preferably be prepared with an intermediary coating, for preference with a suitable solution of resin. This coating will on the one side cling firmly to the grease proof paper, and will on the other side dissolve to a certain extent into the cellulose-varnish solution which is afterwards laid upon it.

For this purpose the cellulose-varnish solution may with advantage be so chosen that it may to some extent combine with the intermediary resin coating, without completely loosening the latter.

This moderate action of the cellulose-varnish coating on the intermediary resin coating is obtained by dissolving the cellulose ester in a dissolving solution which does not aifect the resin, but which contains small quantities, e. g. perhaps 10 to 20% of a good resin dissolver.

It has been shown in a surprising manner that not only the durability and imperviousness to 10 water of the grease proof paper serving as a foundation, are increased by the above-described process, but also that the transparency of the carrier is improved by the use of an intermediary resin coating under the cellulose-varnish coating. 15 The improvement in transparency caused by the preparation of the grease proof paper, e. g. on a coating-machine of known construction, and then by the application of the intermediary resin layer, and even more so by the application of the 20 covering cellulose-varnish coat, is striking.

Example of manufacture Transparent satined grease proof paper pro- 25 'duced e. g. by a long grinding with blunt knives under squeezing of the threads, is prepared by coating or spraying with or by dipping into a 10 to 20% solution of shellac in spirit. The superfluous liquid is then mostly scraped oil, and the paper 30 dried over radiators. To this resin layer is then applied a solution of nitro-cellulose in vinegarether, to which is added a quantity of spirit equal to between 10 and 20% of the total weight. This small quantity of spirit causes a corrosion of the 35 resin layer, resulting in a very firm clinging of the cellulose-varnish layer to the resin layer.

After the drying process a light-sensitive gelatine emulsion is applied to the cellulose-varnish layer. In order to assure a firm clinging of this 40 gelatine emulsion to the paper carrier coated with cellulose-varnish, a thin intermediary coating may preferably be introduced between the layer of varnish and the light-sensitive gelatine layer, as already suggested by the applicant. This may e. g. be contrived by the application of a gelatine solution, produced by dissolving gelatine in volatile organic dissolvers e. g. acetic acid, formic acid, alcohols, ketones etc., or in a mixture of these.

It is advantageous to use such dissolvers so as to a small extent dissolve both the gelatine and the varnishes used, e. g. cellulose-ester or -ether.

The intermediary coating is dried hot; then the gelatine emulsion is applied to the coated side or sides, and at once clings perfectly.

To prevent the rolling or twisting of the emulsionised papers all measures proper to the technique of photographic emulsion may be used.

In place of the shellac forming the intermediary building layer between the paper and the cellulose-varnish, other resins or mixtures of resins may be used. Care must then be taken that these resins do not dissolve completely into the dissolver or dissolving-mixture used for the application of the cellulose coating.

An alteration in the carrying-out of the process, which, however, does not generally give such good results, consists in the addition at the commencement of resins or in given cases, of softening means, in order to improve the strength of the hold upon the paper foundation.

Having now particularly described and ascertained the nature of my said invention and in what manner the same is to be performed, 1 declare that what! claim is:-

1. A process for the manufacture of photographic films, consisting in the application to Pergamyn paper of a layer of varnish, and further in the application to this layer of varnish of a photographically light-sensitive layer.

2. A process for the manufacture of photographic films, consisting in the application to Pergamyn paper of a layer of varnish, and further in the application to this layer of varnish of a photographic gelatina emulsion.

3. A process for the manufacture of photographic films, consisting in the coating of Pergamyn paper on both sides with a layer of varnish, to which layer is applied a photographic gelatine emulsion.

4. A process for the manufacture of photographic films, consisting in the preparation of Pergamyn paper with a resin coating, covered with a layer of varnish, to which layer a photographic light-sensitive coating is applied.

5. 'A process for the manufacture of photographic films, consisting in the application to sharply satinized parchment-substitute paper of a layer of varnish, to the varnish of a layer of gelatine, and to the gelatine layer of a photographic, light-sensitive layer. a

6. A process for the manufacture of photographic films. in the application to sharply satinised parchment-substitute paper of acoatingofvarnishwhichthenreeelvelacoating of geiatine and lastly a photographic gelatine emulsion.

7. A process for the manufacture of photographic iilms, consisting in the covering of sharply satinized parchment-substitute paper with a resin layer, and with a layer of varnish. to which latter is applied a coating of pure gelatine, and finally to the gelatine a photographic gelatine emulsion.

8. A process for the manufacture of photographicfilmsconsistinginutilizingasabase Pergamyn paper, apply l thereto a coating of varnish, with an intermediate layer of a character to adhere to the paper and unite with the varnish, and a light-sensitive emulsion layer applied to the varnish, the intermediate layer being without deleterious eifect on the normal transparency of the body and solubly intermingling with the varnish.

9. A process for the manufacture of photographic films consisting in providing a body of Pergamyn paper, applying a coating of varnish thereto, an intermediate layer'for uniting the varnish and paper, said layer having an adhesive eilect on the paper without detracting from the transparency thereof, the varnish containing a limited proportion of a solvent for the intermediate laver, and a light-sensitive emulsion applied on the surface of the varnish.

10. A process for the manufacture of photographic fllms consisting in providing a body of sharply satinized parchment-substitute paper of natural transparency, applying a layer of cellulose varnish solution thereto, with an intermediate binder adhering to the paper and partly solvent by the cellulose varnish solution, the binder being of a character to avoid detracting from the inherent transparency of the paper, and finally applying a light-sensitive gelatin emulsion to the cellulose varnish through the medium of an intermediary layer of a nature to have a limited solvent eflect on the varnish and gelatin 6 emulsion.

MAX RENKER.