BY Ce-To-3- 2TTORNEY

July 9, 1940. J. S. CUMMINGS 2,207,695 PHOTOGRAPHIC PAPER Filed Oct. 28, 1938

BLUSHED FM PHOTOGRAPHC EMULSION 2 5 ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZYZZZZ2

DISCRETE PARTICLES BASE PAPER CLEAR ENVELOPE 3. 14

INVENTOR JOHN S. CUMMINGS BY ce-to-3- 2TTORNEY

Patented July 9, 1940 2,207,695

UNITED STATES PATENT OFFICE 2,207,695 PHOTOGRAPHICPAPER John Seneca Cummings, Brooklyn, N. Y., assign or to Interchemical Corporation, New York, N. Y., a corporation of Ohio Application October 28, 1938, Serial No. 237,449 3 Clains. (C. 95-8) This invention relates to photographic paper, both cheap and white, water-soluble binders are and has particular reference to a photographic chosen, since the cheap white pigments are paper comprising a cellulose base, a film of opaque in such binders while transparent or "blushed' cellulose derivative composition over translucent in water-insoluble binders. When the paper, and a film of photographic emulsion such papers are coated with photographic emul- 5 thereon, whereby improved color, moisture resist sions, the water in the emulsions quite naturally ance and resistance to change in dimensions is disturbs the paper SOmewhat; and the water used obtained. in the developing and fixing baths has a similar The phenomenon of "blushing" is one well effect. The principal difficulty with conven O known to the coating industry. While unpig tional papers is due to this tendency to absorb 10 mented coating compositions which dry by evap water-when the prints are dry, they often vary oration of Solvent (lacquers) generally dry down in dimensions slightly when compared with the to Smooth homogeneous transparent films, it is original, due to the fact that the moisture con possible to produce non-homogeneous films by tent cannot be controlled accurately. disturbing the solvent balance so that the binder When paper is coated with a blushed film of a 5 is insoluble in the solvent during some portion of cellulose derivative composition, a white coated 5 the film-forming operation, and remains insol paper is obtained without any pigment, together uble thereafter. In such cases, the binder pre with a film of water-insoluble binder. If the film cipitates out in the form of very small discrete is encased in a glossy envelope of clear lacquer, a particles of transparent material, with air be glossy coated paper is obtained with a water 20 tween the particles; the resultant film is trans resistant film, which seals in any water-insoluble lucent or opaque, appears white to the eye and is impurities which may be in the paper stock. generally matte. Nitrocellulose, other cellulose When a gelatin silver salt emulsion is applied to derivatives and resins all can be made to yield such a paper, no softening of the paper occurs, so Such films, either by proper choice of organic that a uniform thin film of silver emulsion may 25 25 Solvents, or by judicious use of water in the film; be applied, thus spreading out the emulsion the methods of producing such films are well evenly and permitting the use of less of it to get known in the art, largely because a knowledge of the desired results. The principal advantage, the conditions which favor blushing permit for however, is that the film does not absorb water mulators to avoid this generally undesirable phe during developing and fixing, thus ensuring faith 30 nomenon. This type of matte translucent opaque ful reproduction of the original negative. white film has heretofore been used to coat cloth Such a photographic paper is shown in the and paper, to produce tracing cloth. accompanying drawing, which is a section In my co-pending application, Serial Number through a sheet made according to my invention. 75,570, filed April 21, 1936, I have disclosed the As shown therein, the finished article comprises 35 35 possibility of controlling the solvent balance in a base f, coated with a film 2, comprising. dis such compositions so that the film deposited dur Crete particles 3 embedded in a clear envelope f4, ing the early stages of drying is clear and trans and having a top coat comprising a photographic parent, while the film deposited in the late stages emulsion 5. is blushed and opaque, whereby a blushed film is Typical examples of my invention are: 4C obtained enclosed in a glossy envelope, yielding a Eacample I glossy opaque finish for paper and the like. Parts by weight I have discovered that such blushed film, when SS nitrocellulose 5 sec. (wet with 30% butyl coated on paper and the like, make exceptionally alcohol).------'m ------a ------13.8 45 fine bases for photographic paper, producing cer Acetone ------5.0 4t tain results heretofore not obtainable with Con Methyl alcohol (C. P.).------74.4 ventional photographic papers. Water------4.2 Ordinary coated papers are made by treating. Glycerine------2.6 ordinary paper with dispersions of pigment in binding materials; because the paper must be 100.0 is 2 2,207,695 This lacquer was coated on regular uncoated Eacample III photographic paper stock, and allowed to dry, to Parts by weight give a glossy coated paper with an opaque, very A sec. SS nitrocellulose (wet with 30% white blushed film enclosed in an envelope of butyl alcohol).------19.0 is clear lacquer. 5 sec. SS nitrocellulose (wet with 30% This paper was then coated with a photographic butyl alcohol)------5.7 emulsion having the following formula: Butyl stearate------2.4 A solution is made of - "Wecoline" ------4.3 GranS Acetone ------20.6 10 Gelatin ------160 Toluol------38.0 Potassium bromide------88 Xylol------run arres or n -v or - or m 10.0 Citric acid------50 Distilled water------1600 Total------100.0 This solution is heated to 35° C., and a cold This lacquer gave a somewhat more flexible s ammoniacal silver nitrate solution is added to it, film than the lacquers of Examples I and II, of the following formula: but gave the same results when coated with pho Grams tographic emulsions. Water ------400 The photographic emulsion shown in Exam Silver nitrate ------00 ple I may, of course, be replaced with other 20 20% ammonia water------150 emulsions used in the photographic industry; and The mixture is maintained at 35° C. for 30 I have prepared and used slower and faster emul minutes, and allowed to gel overnight, then cut sions with comparable results. into threads, and washed carefully. This emul The typical nitrocellulose lacquers shown can sion was heated to 40° C., and 150 grams of gela be replaced by other cellulose derivative lac tin was added; the heating was continued until quers containing derivatives such as cellulose the gelatin was thoroughly absorbed, and the acetate, ethyl cellulose, benzyl cellulose, cellulose emulsion ready for coating on the paper. aceto-butyrate, and mixtures thereof. The resultant paper was free from the water Modifications can obviously be made in the absorptive tendencies of ordinary paper, and examples without departing from my invention, 30 gave prints absolutely free of distortion. which is defined in the claims. I claim: Eacample II 1. A photographic paper comprising a cellulose Parts by weight base, a continuous, glossy blushed film of cellulose A sec. SS nitrocellulose. (wet with 30% derivative on said base, and a photographic butyl alcohol).------170 emulsion on said blushed film. 5 sec. SS nitrocellulose with 30% butyl 2. A photographic paper comprising a cellu alcohol) ------5.0 iose base, a blushed film containing cellulose de Butyl stearate------5 rivative on said base comprising discrete par Cocoanut oil, treated ('Wecoline Pas ticles containing cellulose derivative enclosed in 40 ticizer") ------2.7 a glossy envelope of cellulose derivative lacquer , Ethyl acetate (B. P. 77 C.).------24.0 and a photographic emulsion on said blushed film. Toluol (B. P. 117 C.) ------28.9 3. A photographic paper comprising a cellu Xylol (B. P. 142 C.) ------20.9 lose base, a blushed film containing nitrocellu lose on said base comprising discrete particles Total.------100.0 containing nitrocellulose enclosed in a glossy en Paper coated with this lacquer gave results sim velope of nitrocellulose lacquer, and , a photo ilar to that obtained with the lacquer of Ex graphic emulsion on said blushed film. ample I. JOHN SENECA GUMMINGS.

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