US2075047A - Photographic emulsion containing supersensitized pseudocyanines - Google Patents

Description

March so, 1937. c E, K, MEES 2,075,047.

PHOTOGRAPHIC EMULSION CONTAINING SUPERSENS ITIZ'ED PSEUDOCYANINES Original Filed Nov. 4, 1932 Patented Mar. 30, 1937 PHOTOGRAPHIO EMULSION CONTAINING SUPERSENSITIZEI) PSEUDOCYANINES Charles E. K. Mees, Rochester, N. Y., assignor, by

mesne assignments, to Eastman Kodak Company, Jersey City, N. J., a corporation of New Jersey Application November 4, 1932, Serial No. 641,178 Renewed February 9, 1935 15 Claims.

This invention relates to sensitized photographic emulsions and more particularly relates to photographic emulsions such as those of the gelatino-silver-halide type containing a combination of sensitizers, one of which cooperates with the other to sensitize the emulsion to a much greater degree than is possible with that sensitizer, or either sensitizer alone, or even than would be evidenced by the sum total of the sensitization produced by the two separate sensitizers individually.

In other words, I have found that the sensitivity contributed to photographic emulsions by certain sensitizers may be enhanced to a very is considerable degree by adding to the basic sensitizer what I will term a supersensitizer, the latter contributing to the emulsion the sensitivity which is peculiar to itself as well as activating or inducing further sensitivity in what I will term 20 the basic sensitizer. For example, a certain basic sensitizer may have a green speed of 50 H and D but when there is added thereto a supersensitizer, which may not even sensitize to the green at all (but to some other portion of thegreen speed. Or, assuming the basic sensitizer to sensitize the emulsion to a green speed of 50 and the supersensitizer to separately sensitize the 30 emulsion to a green speed of 5, the addition of thesupersensitizer to the basic sensitizer will sensitize the emulsion to a green speed beyond the sum total of the two separate green speeds, namely to a green speed, for instance of 80.

35 The combinations ofsensitizers and supersensitizers which are the subject of the instant invention have the peculiar property that, in order for the supersensitizer to increase the sensitivity of the basic sensitizer, the region of sensitivity of 40 the supersensitizer must coincide at least inpart with the region of sensitivity of the basic sensitizer. The unusual effects obtained by the combinations of sensitizers which constitute the instant invention result, therefore, from the unusual in- 45 fluence or relation which the supersensitizers have upon or to the respective basic sensitizers.

Accordingly, it is among the objects of my invention to provide a photographic emulsion which contains a basic sensitizer for the emul- 50 sion and which also contains a supersensitizer which contributes its own individual sensitization to the emulsion and also increases the sensitization caused by the basic sensitizer. It is a further object of my invention to provide certain 55 combinations or mixtures of sensitizers in a photographic emulsion which will contribute to the emulsion a sensitivity '(ability to respond to light) not heretofore obtainable with either of the. individual sensitizers in the combination. Other objects will become apparent to those skilled in the art upon a further perusal of this specification.

- I have found, for instance, that the sensitivity styryl compounds as a supersensitizer. I find this supersensitizing effect upon the sensitizing propertiesof pseudocyanines to be general with or representative of certain styryl compounds, which themselves have the ability of separately sensitizing photographic emulsions to some degree.

Referring to the attached drawing, forming a part hereof, there is represented a hypothetical wedge spectrogram illustrating .my invention.

The curve A shows the approximate sensitivity conferred upon a gelatino-silver-halide emulsion by a pseudocyanine as a basic sensitizer. The curve B illustrates diagrammatically the sensitivity separately conferred upon the same gelatino-silver-halide emulsion by a styryl compound. The curve C, however, illustrates the sensitivity of the same photographic emulsion containing a small percentage of a solution in which is dissolved approximately equal parts of the pseudocyanine and the styryl compound. From this it will be apparent that the combination or mixture of these sensitizers contributes to the photographic emulsion a sensitivity far beyond that which it is possible to obtain even from the sum total of the sensitization resulting from the individual sensitizers.

More specifically my invention is accomplished by dissolving the sensitizing dyes in, for instance, methyl alcohol. The sensitizer and supersensitizer are added to the alcohol, for instance, in equal proportions, although I have found that less than an equal amount of the supersensitizer is normally sufficient to confer upon the sensitizer an increased sensitvity. For example, while I may dissolve in the methyl alcohol solvent one part of the pseudocyanine, I may then add to the alcohol from fith'part or even less of the styryl compound to one part or even more of the styryl compound, depending upon the effect that is desired in the photographic emulsion. The exact ratio of the supersensitizer to the sensitizer is not particularly important inasmuch as those skilled in the art can readily determine by what ratio the greatest degree of sensitization of the basic sensitizer can be obtained.

This solution of the sensitizer and supersensitizer is then diluted with water and a volume containing from a few milligrams to as much as 100 milligrams, and preferably from about to 30 milligrams of the sensitizers, is then 10 added to 1000 cc. of a gelatino-silver-halide emulsion, such as is customarily employed in the art. Obviously, if the pseudocyanine is greatly supersensitized by the styryl compound, less of the sensitizer combination will be necessary to obtain the desired degree of sensitization in the emulsion. The emulsion may then be coated upon a transparent support, as is well known in the art, either glass, or cellulose nitrate or acetate, or other cellulose derivative,

0 base being satisfactory as the support.

As further illustrating my invention, I have tabulated hereinafter typical examples of styryl compounds which themselves have the power of sensitizing a photographic emulsion and also have the ability of supersensitizing the sensitizing effect of the pseudocyanine on the photographic emulsion. Styryl compounds which are characteristic of those which I may employ as supersensitizers for pseudocyanines, opposite which they are set, are as follows l :2 diethyl seleno-pseudocyanine iodide. 6 (6) methyl 1:1 diethyl pseudocyanine iodide 1:1 diethyl pseudocyanine iodide 1:1 diethyl psendocyanine iodide 4 methyl 2 (p. diethyla- 4 phenyl 3 methyl 1 ethyl selenazolo mino) styryl thiazole pseudocyanine iodide ethiodide 4 phenyl 3 methyl 1 ethyl selenazolo 1'22 diethylthiopseudocyanine iodide l:2 diethyl pseudocyanine iodide 2 (pdlmethylamlno) y ryl thiazoline methiodide 2 (p. dimethylamino) styryl benzothiazole ethiodide 2 (p. dimethylamino) styryl 6 ethoxy quinoline n-butiodide 2 (p. dimethylemino) styryl quinoline ethiodide 1'z2 diethyl pseudoeyenine iodide 0 1&2 dlethyl pseudocyanine iodides.-.

122 diethylthiopseudocyenine iodide.-.

These examples illustrate a class of styryl compounds which I have found will act as supersensitizers for pseudocyanines and which class may be defined as dialkylamino styryls which contain a heterocyclic nitrogen containing nucleus or ring which latter may be substituted, if desired, so long as such substitution does not destroy the power of the styryl to separately sensitize a photographic emulsion; I regard a fused-on benzene ring as being within the foregoing definition, as for instance in the case of a quinoline or benzothiazole nucleus.

These examples also illustrate that, as basic sensitizers, the pseudocyanines all appear to be susceptible of being supersensitized by the class of styryls described. It willbe noted that these 7;) may contain a nucleus containing either sulphur or selenium or may contain merely a quinoline nucleus. They are further characterized in that those pseudocyanines most readily susceptible to supersensitizing, have a sharp 75 peak or maximum in their region of spectral sensitivity. While the nuclei of these pseudocyanines may be substituted as illustrated above, too heavy a substitution may result in a pseudocyanine which will not respond notably to supersensitization as in the case, for instance of 1 methyl 1' ethyl 6 dimethylamino pseudocyanine iodide.

The basic structure and source of the basic sensitizers and the supersensitizers above named are well known to those skilled in the art, either being set forth in the published literature, or in available patents, so that the description of their methods of preparation is unnecessary.

Other examples showing the broad application of my invention could be cited but the foregoing will be sufiicient to teach those skilled in the art, the manner in which my invention is carried out and the broad principle of supersensitizing basic sensitizers of numerous types with compounds which themselves have separate sensitizing properties and the regions of sensitivity of which coincide at least in part with the respective regions of sensitivity of the basic sensitizers.

Numerous variations to the above invention will doubtless occur to those skilled in the art and will be included in the scope of my invention as defined by the claims appended hereto, it being understood that the foregoing is merely illustrative of the manner of practicing my invention and the results to be obtained thereby.

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

1. A gelatino-silver-halide emulsion containing two sensitizers for the emulsion, one of which is a pseudocyanine, as a basic sensitizer, and the other of which is, as a supersensitizer, a dialkylamino styryl derivative of an alkyl quaternary salt of a simple nitrogen-containing heterocyclic base.

2. A gelatino-silver-halide emulsion containing two sensitizers for the emulsion, one of which is a pseudocyanine, as a basic sensitizer, and the other of which is, as a supersensitizer, a dialkylamino styryl derivative of an alkyl quaternary salt of a simple nitrogen-containing heterocyclic base which base carries as substituents, alkyl groups or alkoxy groups or a fused-on benzene ring.

3. A gelatino-silver-halid'e emulsion containing two sensitizers for the emulsion, one 01' which is, as a basic sensitizer, a pseudocyanine which possesses a relatively sharp maximum in its region of spectral sensitivity, and the other of which is, as a supersensitizer, a dialkylamino styryl derivative of an alkyl quarternary salt of a simple nitrogen-containing heterocyclic base.

4. A gelatino-silver-halide emulsion containing two sensitizers for the emulsion, one of which is, as a basic sensitizer, a. pseudocyanine which possesses a relatively sharp maximum in its region of spectral sensitivity and the nuclei of which do not carry a dialkylamino group as a substituent, and the other of which is, as a supersensitizer, a dialkylamino styryl derivative of an alkyl quaternary salt of a simple nitrogen-containing haterocyclic base.

5. A gelatino-silver-halide emulsion containing two sensitizers for the emulsion, one of which is a thiopseudocyanine, as a basic sensitizer, and the other of which is, as a supersensitizer, a dialkylamino styryl derivative of an alkyl quat nary salt-of a simple nitrogen-containing heterocyclic base.

6. A gelatino-silver-halide emulsion containing two sensitizers for the emulsion, one of which is a selenopseudocyanine, asa basic sensitizer, and the other of which is, as a supersensitizer, a dialkylamino styryl derivative of an alkyl quaternary salt of a simple nitrogen-containing heterocyclic base.

I. A gelatino-silver-halide emulsion containing two sensitizers for the emulsion, one of which is a lzl'dialkyl pseudocyanine halide, as a basic sensitizer, and the other of which is, as a super sensitizer, a dialkylamino styryl derivative of an alkyl quaternary salt of a simple nitrogen-com taining heterocyclic base.

8. A gelatino-silver-halide emulsion containing two sensitizers for the emulsion, one of which is a 1:1 dialkyl pseudocyanine halide, as a basic sensitizer, and the other of which is pinafiavol as a supersensitizer.

9. A gelatino-silver-halide emulsion containing two sensitizers for the emulsion, one of which is 1:1 diethyl pseudocyanine iodide, as a basic sensitizer, and the other of which is, as a supersensitizer, a'diaikylamino styryl derivative of an alkyl quaternary salt of simple nitrogen-containing heterocyclic base.

10. A gelatino-silver-halide emulsion containing two sensitizers for the emulsion, one of which is a 6 alkyl 1:1 dialkyl pseudocyanine halide, as a basic sensitizer, and the other of which is pinaflavol as a supersensitizer.

11. A gelatino-silver-halide emulsion containing two sensitizers for the emulsion, one of which is 6 methyl 1:1 diethyl pseudocyanine iodide, as a basic sensitizer, and the other of which is pinafiavol as a supersensitizer. I

12. A gelatino-silver-halide emulsion containing two sensitizers for the emulsion, one of which is a 4 aryl 3:1 dialkyl thiazolo pseudocyanine halide, as a basic sensitizer, and the other of which is pinaflavol as a supersensitizer.

13. A gelatino-silver-halide emulsion containing two sensitizers for the emulsion, one of which is 4 phenyl 3:1 dimethylthiazolo pseudocyanine iodide, as a basic sensitizer, and the other of which is pinaflavol as a supersensitizer.

14. A photographic element comprising a gelatino-silver-halide emulsion containing two sensitizers for the emulsion, one of which is a pseudocyanine, as a basic sensitizer, and the other of which is, as a supersensitizer, a dialkylamino styryl derivative of an alkyl quaternary salt of a simple nitrogen-containing heterocyclic base.

15. A photographic element comprising a gelatino-silver-halide emulsion containing two sensiti'zers for the emulsion, one of which is, as a basic sensitizer, a pseudocyanine which possesses a relatively sharp maximum in its region of spectral sensitivity, and the other of which is, as a supersensitizer, a dialkylamino styryl derivative of an alkyl quaternary salt of a simple nitrogen-containing heterocyclic base.

CHARLES E. MEES.

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