US1939171A - Photographic film base and coating therefor - Google Patents

Description

Dec. l2, 1933. Kc. D. HICKMAN l 1,939,171

PHOTOGRAPHIC FILM BASE AND COATING THEREFOR Filed April 7, 1951 SW1/woz,

dftonwg Patented Dec. 12, 1933 UNITED STATES PHOTOGRAPHIC FILM BASE AND COATING THEREFOR Kenneth C. D. Hickman, Rochester, N. Y., as-

signor to Eastman Kodak Company, Rochester, N. Y., a corporation of New York Application April 7, 1931. Serial No. 528,266

9 Claims.l

This invention relates' to photographic illm and to coatings adaptedto be applied thereto for the purpose of improving the characteristics of the hn and particularly adapted to prevent halation.

' I have discovered that the soluble derivatives of cellulose are particularly useful for this purpose when combined with, or used as a carrier for, dyes or other coloring media. When such a coating is applied to the back oi a photographic film, that is to say, the side opposite to that upon which the light-sensitive emulsion is applied, the coating Will absorb light which is transmitted through the emulsion and the ilm so that reilection of the light and the halation eiects resulting therefrom are entirely or substantially overcome. Such coatings being water soluble are removed completely from the iilm when the latter is subjected to the actions of a water solution, as in the subsequent treatment of the lm in the developing and xing baths. Consequently, the film,l when the developing and xing operation is completed, has its normal appearance.

I will now describe my inventionmore completely, referring when necessary'to the accompanying drawing in the several gures of which the same reference characters designate the.

same parts and in which Fig. 1 is a section on an enlarged scale of one embodiment of my invention.

Fig. 2 is a similar section of another embodiment of my invention.

Fig. 3 is a similar section of a third ment.

AThe object of the invention may be attained in various ways. For example, a solution of cellulose aceto-lactate in water may be combined with a suitable water soluble dye or adrnixed with a pigment and applied to the illm. Such an aceto-lactate is described in the pending application of. C. J. Staud and C. S. Webber, Serial No. 341,032, led February 18, 1929. Various dyes of this type are available such as nigrosine. The solution may be applied to the illm by a well understood procedure as a thin layer. When dry it provides a thin coating on lthe illm which prevents halation and is readily removed when the lm is subjected subsequently to treatment in water solutions. Alternatively, a water solution of the ester oi' cellulose can be applied to the lm and dried, forming a thin transparent coating as a baseor undercoating fora coating of a spirit soluble dye. Numerous dyes of'thls character can be used such as spirit blue R or nigroline. A solution of the dye is applied over the embodi- .the albumen insoluble in water.

undercoating of the water soluble ester of cellulose Which it permeates more or less completely. It prevents halation and is readily removable when the lm is thereafter subjected to a Water solution.

" In Fig. 1, the film made by either of the above processes is shown, the support being designated 1, the sensitive emulsion layer 2, and the backing of cellulose derivatives including a dye being designated 3.

In a modified procedure, the film may be irst provided with a coating of the water soluble solution cellulose derivative. A coating of an alcohol soluble dye may then be applied and a final protective coating of the water soluble cellulose derivative may be, added. When such a ilm is placed in a water solution, the outer layer consisting of the cellulose ester is dissolved and sufl cient water diffuses through the dye coating to soften the undercoating of soluble cellulose ester. The layers are thus easily removed from the lm to leave it in atransparent state.

Such a fllm is shown in Fig. 2, wherein 1 and 2 represent, as in Fig. 1 the support and sensitive layer respectively, the first coating of soluble cellulose derivate is shown at 4, the dye layer at 5 and the outer protective layer at 6.

The water soluble esters of cellulose are subject to the effect of humidity in the atmosphere. Consequently, under certain climatic conditions, it is preferable to apply, as the outer protective coating 6, a water insoluble material. Thus, a coating of the soluble cellulose ester, either including a dye as at 3, Fig. 3, or as a base layer 4 for an alcohol soluble dye layer 5, may be applied to the film. Thereafter, the lm receives a coating of material 6 or 7 which is insoluble in water but soluble in alkaline solutions such as are employed in the development of photographic films. A suitable material is a solution of egg albumen in water. The latter coating after drying may be subjected to suiiicient heat to render It is readily soluble, however, in alkaline solutions, and the coating including the water soluble ester of cellulose is removed when the film is subjected to development.

Another material which is useful as the top or waterproofing coating 6 or 7 is cellulose nitrate in a solvent such as ethyl acetate or butyl acetate, coated over the soluble layer very thinly. There 'are available also for use in such protective layers a number of water `insoluble proteins; Thus a layer oi. water insoluble but alkali soluble casein may be used. .Also a spirit soluble gum or no "lll the lm consisting of resin such as Sandarac with a small amount of `wax such as stearic acid dissolved in ethyl Formula I Parts Cellulose aceto-lactate 4 Water 90 Glycerine 11 Saponine f6 Dye 5 Before using this mixture, 1x6 part by weight of egg albumen is dissolved in 10 parts of water and the latter solution is added to the cellulose acetolactate solution. I may include, as hereinbefore indicated, a water soluble dye such as nigrosine in the proportion of 5 parts by weight in the solution as described, or the solution without the dye may be applied to the illm as a base for an alcohol soluble dye. For the latter solution I prefer to employ 2 parts by weight of nigrosine in 88 parts by weight of ethyl alcohol. After the coating of undyed cellulose aceto-lactate is dry, the alcohol soluble dye is applied to the lm and an overcoating of cellulose aceto-lactate, similar to the ilrst, may be then applied. If dye is included in the cellulose aceto-lactate solution, one coating is sufficient.

An example of a more water resistant coating is:

This solution is made slightly alkaline to phenolphthalein. This solution can be applied to the film either with or without the addition of a little acetone. The dried coating of albumen may be rendered insoluble in water by passage over heated calenders at a temperature of approximately C. This coating is insoluble in water but is soluble in alkaline solutions such as are employed glrnonly for the development of photographic An alternative method of carrying out the invention is as follows. A first layer is applied to Formula III Y Parts Cellulose aceto-tartrate 50 Acid blue black 20 Tartrazine 5 Egg albi-Iman 2() Saponine 1 Glycerine 1 Water 903 When this has dried, a second layer is applied of Formula IV Parts Cellulose nitrate 10 Butyl acetate 200 Ethyl acetate 800 This is dried in the usual manner. The resulting nlm has a greenish black layer which is smooth and durable, and is removed as a coherent skin or in flakes in a few minutes in a stream of water.

'Ihe removal of the outer coating permits water to attack the soluble ester of cellulose forming the under coating thus permitting removal of the dye from the lms during the normal development of the film.

It is apparent from the above that a nonhalation layer made in accordance with my invention may consist of one, two or more separate layers or coatings. Finally, the dyes may be contained in any of the layers in various combinations or alone.

While I have described particularly the use of cellulose aceto-lactate, it is to be understood that I contemplate as equivalents the other known soluble mixed esters and other derivatives such as soluble cellulose ethers, soluble cellulose acetates or soluble cellulose xanthates. In general these have the advantages that they adhere strongly to the support but can be dissolved cleanly from it; the layer acts as an insulation layer protecting the support from permanent staining by the dye, in some cases they act as anti-static layers.

In the term non-halation layer it is understood that I include any of the above combinations, whether of one or more actual layers or coatings. l

Various changes may be made in the procedure and particularly in the constituents and the proportions thereof in the coatings without departing from the invention or sacrificing any of its l advantages.

What I claim as my invention and desire to secure by Letters Patent of the United States is:

1. A non-halation photographic element comprising a light-transmitting supporting layer, a photographically sensitive layer on one face thereof, and a layer comprising a water-soluble cellulose derivative and a light absorbing medium carried on the other face of the supporting layer.

2. A non-halation photographic element comprising a light-transmitting supporting layer, a photographically sensitive layer carried on one face thereof, and a layer of a water-soluble mixed cellulose ester carrying a light absorbing medium carried in the other face of the supporting layer. 3. A photographic lm comprising a supporting layer of an insoluble cellulosic plastic material, a photographically sensitive layer carried on one face thereof, and a layer containing cellulose aceto-lactate on the other face thereof.

4. A non-halation photographic 111m comprising a light-transmitting supporting layer, a photographically sensitive layer on one face thereof, and a layer containing cellulose acetolactate and `a dye on the other face thereof.

5. A non-halation photographic film comprising a light-transmitting supporting layer, a photographically sensitive layer on one face thereof, a layer of a water-soluble cellulose derivative carrying a light absorbing coating on the other face thereof, and a protective coating over said layer.

6. A non-halation photographic film comprising successively a photographically sensitive layer, a light transmitting supporting layer, and a layer of a water-soluble Vcellulose derivative carrying a light absorbing coating and a waterinsoluble protective coating over said layer.

7. A'non-halation photographic film comprising successively a photographically 'sensitive layer, a light transmittingsupporting layer,.and a layer of a water-soluble mixed ester ofcellulose carrying a light absorbing medium and a protective coating of water-insoluble protein.

ing successively a photographically sensitive layer, a light transmitting supporting layer, a layer of avWater-soluble mixed ester of cellulose carrying a light absorbing medium and a protective coating of water-insoluble protein which is soluble in an alkaline solution.

KENNETH C. D. mcKMAN.

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