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Carl-Fra by ATTORNEY 5 Dgent Patented Aug

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Carl-Fra by ATTORNEY 5 Dgent Patented Aug Aug. 18, 1953 H. l. DAVIS 2,649,375 LIGHT-SENSITIVE PHOTOGRAPHIC ELEMENT Filed Oct. 26, 1950 PHO7OGRAPHIC . S/L/AR Ada L/PE FMUS/OW 11 %3 cellulose ASTER owTAINING 10 N LESS 7 Alamy O. ooz, 7- DE77/YLAM/NO-4-METHYLCOUMARIN HARRY I. DAVIS INVENTOR Carl-fra BY ATTORNEY 5 dGENT Patented Aug. 18, 1953 2,649,375 UNITED STATES PATENT OFFICE 2,649,375 LIGHT-SENSTIVE POTOGRAPHIC ELEMENT Harry I. Davis, Rochester, N.Y., assignor to East man Kodak Company, Rochester, N. Y., a cor poration of New Jersey Application October 26, 1950, Serial No. 192,285 10 Claims, (C. 95-9) 1. 2 This invention relates to photographic elements der ultra-violet radiation. It was most unex and a method for identifying them. pected to find that Over a certain range 7-di Motion picture film is ordinarily identified ac ethylamino-4-methylcoumarin could be advan cording to the manufacturer and type (e. g. cellu tageously used without having a deleterious effect lose acetate or cellulose nitrate) by exposing let 5 on the photographic emulsion. 7-diethylamino ters or symbols photographically along the mar 4-methyl coumarin has no detectable effect on the gins of the raw or unprocessed film. Upon de Color of the film base and is insoluble in water velopment, these markings become visible and or the solutions used in film processing, when permit identification of the film. used in accordance with the process of my in The difficulty with such a means of identifica () vention. tion is that each foot of film must be separately Whereas the use of fluorescent materials in inspected, which is a somewhat laborious proc inks and the like for identifying certain materials ess. Identification is made even more difficult has long been known, many of these materials when separate lots of film are spliced together are unsuited for use in connection with the iden and different types of film are made into a single tification of photographic elements because of strip. Rapid identification of film is quite im their adverse effect on the color of the film base portant in recovery of scrap film or in the vault or their fogging action on the light-sensitive storage of film, where cellulose acetate type must emulsion coated on the base. These and other be distinguished from cellulose nitrate type film. difficulties are avoided when 7-diethylamino-4- It is, therefore, an object of my invention to methylcoumarin is used as the fluorescent ma provide a new photographic element. A further terial in photographic elements in accordance object is to provide a method for distinguishing With my invention. - one film type from another quickly and accu In the copending application Serial No. 191,017, rately. Still another object is to provide a new filed on October 19, 1950, of Ralph H. Talbot, composition of matter. Other objects will be- 2: a method for identifying photographic elements come apparent from a consideration of the fol comprising adding Small amounts of anthracene lowing description and exampleS. to the film base, e. g. cellulose acetate, is de According to my invention, I provide new pho scribed. While the method of that application tographic elements having a cellulose ester Sup offers certain advantages over the prior art, I port containing from 0.0001 to 0.002 per cent : have found that the 7-diethylamino-4-methyl by weight, based on the cellulose ester, of 7-di counarin of my invention offers further advan ethylamino-4-methylcoumarin. On inspection tages in that the counarin compound is effective of the photographic element under ultra-violet in amounts varying from about one-fortieth to radiation, a purplish fluorescence of sufficient in one-fiftieth of the anthracene. tensity for identification purposes is exhibited. 7-diethylamino-4-methylcoumarin is a known It is known that fluorescent materials can be Substance and has been described in Miglarese added to the film base of photographic elements. U. S. Patent 2,334,348, dated November 16, 1943. For example, Michaelis U. S. Patent 2,331,492, Its structure can be represented as follows: dated October 12, 1943, describes a photographic element containing a fluorescent material, such 40 H. as rhodamine, in the film base. The purpose of the fluorescent layer of Michaelis is to provide a source of radiant energy to cause exposure of a light-sensitive emulsion, which is not sensi ol O Ce:O tive to primary radiation. Other patents show The accompanying drawing shows a film base the use of fluorescent materials in the film base. of a cellulose ester containing 7-diethylamino-4- of a photographic element for the purpose of methylcoumarin and a coating of a photographic image intensification. I have now found that Silver halide emulsion on the film base. A fur by using very small amounts of 7-diethylamino ther description of the photographic elements 4-methlycoumarin in the film base of a pho 50 of my invention is given below. tographic element, the fluorescent properties of The amount of 7-diethylamino-4-methyl the 7-diethylamino-4-methylcoumarin have no counarin used in my invention is of material substantial effect on the light-sensitive emulsion importance in determining the properties of the layer, but are sufficient to permit identification cellulose ester film base, and consequently, the of the photographic element upon inspection un 55 photographic element comprising the cellulose 2,649,375 3 4. ester film base. An amount less than 0.0001 per photographic silver-halide emulsion f f. Instead cent should not be used, nor should an amount of a single photographic silver-halide emulsion, in excess of 0.002 per cent be used, the amounts the Support 10 can be coated with a plurality of being based on the cellulose ester, since the ad enulsions, for example, as shown in U. S. Patents vantageous results of my invention are not ob 2,350,764, dated June 6, 1944; 2,360,214, dated tained outside this range. October 10, 1944; 2,376,202, dated May 15, 1945; The 7-diethylamino-4-methylcoumarin can ad 2,391,198, dated December 18, 1945; 2,403,721, vantageously be added to a viscous Solution or dated July 9, 1946; etc. The photographic emul "dope' of the cellulose ester, and the composi Sion layer , and those described in the above tion agitated until homogeneity is accomplished. 0 U.S. patents are the usual gelatino-silver halide The 7-diethylamino-4-methylcoumarin can be enulsions customarily used in the art of black added in solid form, or in the form of a Solution, and-white or multi-color reproduction. These which contains, for example, the same Solvent emulsions can also consist of silver halide dis present in the cellulose ester dope. After inti persed in other water-permeable colloidal mate mate mixing the Solution is cast into a sheet and 5 rials, such as Synthetic resins, e. g. polyvinyl the solvent removed by evaporation. A film of alcohol, etc., cellulose ethers and esters, etc. the cellulose ester can be first formed and a Typical Silver-halide emulsions include silver coating of 7-diethylamino-4-methylcoumarin ap chloride, bromide, bromiodide, and chlorobro plied to the cellulose ester layer, although I have mide types. The photographic silver-halide found that a product is obtained which does not 20 emulsions can contain the usual addenda, such as exhibit the homogeneity and abrasion resistance polymethine Sensitizing dyes, anti-foggants, etc. shown by the product obtained from a cellulose What I claim as my invention and desire ester dope containing the 7-diethylamino-4- Secured by Letters Patent of the United States methycoumarin. A film of cellulose ester can 1S also be immersed in a solution of the 7-diethyl 2 5 i. A photographic element comprising at least annino-4-methycoumarin in a Solvent having no Gle photographic Silver halide emulsion layer dissolving power for the cellulose ester. Such and a colorless cellulose ester layer containing nodes of procedure are not generally to be pre from 0.0001 to 0.002 per cent by weight, based ferred since the amount of t-diethylaimino-4- On the cellulose ester, of 7-diethylamino-4-meth methylcounarin used cannot be as Systematically 30 yicouinarin, said cellulose ester being an ester of controlled and the 7-diethylamino-4-methylcou a Saturated carboxylic acid containing frona 2 to marin is easily removed from the film base 4 carbon atoms. during handling. 2. A photographic element comprising at least Cellulose esters which can advantageously be one photographic silver halide emulsion layer used in my invention cornprise cellulose acetate, and a colorless cellulose acetate layer containing cellulose propionate, cellulose butyrate, etc., from 0.000 to 0.002 per cent by weight, based mixed cellulose esters, Stich as cellulose acetate on the cellulose acetate, of 7-diethylamino-4- butyrate, etc. My invention is particularly methylcoumarin. adaptable to the use of cellulose acetate contain 3. A photographic element comprising at least ing, for example, from 35 to 44.8 per cent acetyl. 4 one photographic silver bromide emulsion layer The particular solvent, or mixture of Solvents, and a colorleSS cellulose ester layer containing used in the cellulose ester dope will depend on from 0.0001 to 0.002 per cent by weight, based the acyl content of the ester. For example, cellu On the cellulose ester, of 7-diethylamino-4-meth lose acetate containing from about 39 to 41 per ylcoumarin, said cellulose ester being an ester of cent acetyl can be dissolved in acetone. a saturated carboxylic acid containing from 2 to Cellulose acetate containing from about 42.5 to 4 carbon atoms.
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