US3873323A - Spectrally sensitized silver halide photographic emulsions - Google Patents

Abstract

A silver halide photographic emulsion containing at least one sensitizing dye represented by the general formula:

HAS HIGH SPECTRAL SENSITIVITY IN THE VICINITY OF 460 - 490 M Mu . Moieties R1 - R4 are defined in the specification.

Description

llnited States Patent Nakamura et al.

[4 1 Mar. 25, 1975 SPECTRALLY SENSITIZED SILVER HALIDE PHOTOGRAPHIC EMULSIONS [75] Inventors: Yasuharu Nakamura; Yoshiyuki Nakazawa; Tohru Sueyoshi; Akira Sato; Tadashi ldeda, all of Kanagawa, Japan [73] Assignee: Fuji Photo Film Co., Ltd.,

Kanagawa, Japan [22] Filed: May 31, 1973 [21] App]. No.: 365,677

[30] Foreign Application Priority Data May 31, 1972 Japan 47-54497 [52] U.S. Cl. 96/120, 96/107 [51] Int. Cl G03c l/02 [58] Field of Search 96/120, 107

[5 6] References Cited UNITED STATES PATENTS 2.111162 3/1938 Kendall 96/120 141L507 11/1946 Collins ct al. 96/120 3.629374 l2/l97l Oliver lo/ill) Primary E.\'uminerJ. Travis Brown Attorney, Agent, 0rF1'rmSughruc, Rothwcll, Mion, Zinn & Macpeak [5 7] ABSTRACT A silver halide photographic emulsion containing at least one sensitizing dye represented by the general formula:

1 Cl N R; (I ca-ca =c 01 N has high spectral sensitivity in the vicinity of 460 490 mp. Moieties R, R4 are defined in the specification 7 Claims, 1 Drawing Figure PATENTEDHARZ'J'IQB 3,873,323

SENSITIVITY+ WAVE LENGTH m u srEcTn A iLv s liiv sirlznii sitvan ii /tuna PHOTOGRAPHIC EMULSIONS BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a silver halide photographic emulsion containing novel sensitizing dyes, and particularly to a silver halide photographic emulsion having a high spectral sensitivity in the vicinity of 460 490 mu.

2. Description of the Prior Art In the manufacturing of silver halide photographic emulsions it has been well known that when a sensitizing dye is added to the silver halide photographic emulsion the sensitive wave length region is expanded.

It has been well known that the spectrally sensitized wave length region and the spectral sensitivity of silver halide photographic emulsions containing sensitizing dyes are influenced by the chemical structure of the sensitizing dyes and, especially, by the kinds of hetero rings and the substituents on the sensitizing dyes.

Sensitizing dyes ofen display spectral sensitizations' which are not expected at all due to a slight difference in chemical structure, and the sensitization due to the J-aggregate (J-band) of sensitizing dyes depends on the chemical structures of the sensitizing dyes.

The sensitization due to the J-aggregate of a sensitizing dye is effective for the spectral sensitization in the region of a specified wave length, and it is very important to develop sensitizing dyes which form the J aggregate in order to highly sensitize a specified wave length region desired in the silver halide photographic sensitive material.

For example, the energy distribution of a light source used in the facsimile field has a peak in the vicinity of 480 my. Therefore, it is desirable that a photographic emulsion used in the facsimile art has a maximum sensitization in the vicinity of its peak, e.g., about 460 490 mu.

However, there are little or no dyes which form the J-aggregate in the vicinity of 460 490 my and, if any do form the J-aggregate, the sensitivity thereof is too low.

SUMMARY OF THE INVENTION It has been found that new sensitizing dyes which are described in detail below are useful ones that form the J-aggregate and strongly spectrally sensitize the wave lengths region in the vicinity of 460 490 mu.

The object of this invention is to provide a silver halide photographic emulsion having high spectral sensitivity in the vicinity of 460 490 m J., and it has been accomplished by adding to a silver halide photographic emulsion novel sensitizing dyes of the following general wherein R and R each represents identical or different alkyl groups as are conventionally used in cyanine dyes, i.e., both substituted and unsubstituted alkyl groups such as methyl, ethyl, n-propyl, n-butyl, carboxyalkyl (for example, carboxymethyl, B-carboxyethyl, 'y-carboxypropyl, 8-carboxybutyl,etc.), alkoxyalkyl groups (for example, B-methoxyethyl), hydroxyalkyl groups (for example, B-hydroxyethyl etc.), acyloxyul kyl groups (for example, y-acetoxypropyl), sultoalkyl groups (for example, B-sulfoethyl, 'y-sulfopropyl. y-sulfobutyl, 8-sulfobutyl, etc.). aralkyl groups (for example, benzyl, phenethyl, p-carboxyphenethyl). vinylmethyl; and R and R may be identical or different and each represents an acyl group, i.e., aromatic acyl group (e.g., benzoyl, etc.) or an aliphatic acyl group, preferably having up to 3 carbon atoms (e.g., acetyl, propionyl, etc.) or an alkoxycarbonyl group (for example, methoxycarbonyl, ethoxycarbonyl, etc.).

In the above formulae, most preferred are those wherein any alkyl moiety which is present contains up to 4 carbon atoms, except for the alkyl moiety of the alkoxy or alkoxy carbonyl group, which preferably contain up to 3 carbon atoms.

As defined in general formula (I), the features of sensitizing dyes used in this invention reside in the fact that they have a 5,6-dichlorobenzimidazole nucleus as a hetero ring and an acyl or alkoxycarbonyl group as the terminal group. Those dyes having such a chemical structure readily form the J-aggregate and are effective to increase the spectral sensitivity in the vicinity of 460 490 mu.

BRIEF EXPLANATION OF DRAWING FIG. 1 shows spectral sensitivity curves, in which (a) shows the spectral sensitivity curve of a silver halide photographic emulsion containing sensitizing dye (I) used in this invention and (b) shows the spectral sensitiviy curve of an otherwised identical emulsion where dye (I) is replaced with control sensitizing dye A.

DETAILED DESCRIPTION OF THE INVENTION Typical examples of the novel sensitizing dyes of general formula (I) which are used in this invention are shown below, with the proviso that the sensitizing dyes used in this invention are not restricted to these examples.

Cl III COCII Dye 3 Cl N coca n =CH-CH=C c1 N I cooc a a Cl coca =caca=c c1 coca-t Dye 5 v (I3ZH5 Cl N coca U .=ca-ca=c c l \rlr COOC H Dye 6 c1 /N coca =CHCH=C Cl 1T COOC2H5 A typical synthesis example of a sensitizing dye used in this invention is as follows. Reference should also be made to the text The Chemistry of Heterocyclic Compounds, The Cyanine Dyes and Related Compounds, Francis M. Hamer, lnterscience Publisher.

Ethyl-4-(5,6-dichloro-l,3-diethyl- Synthesis A of 2( 1H )-benzimidazolylidene )-2-acetyl-2-butenoate (Dye 1) 5 g of 5,6-dichloro-1,3-diethyl-2-(B-N- acetylanilinovinylene) benzimidazolium iodide and 2.5 g (100 percent excess) of acetoacetic acid ethyl ester were dissolved in 6.0 ml of ethanol, 3 ml of triethylamine was added, the system heated for 1 hr. under reflux at atmospheric pressure, then cooled, and 300 ml of water added and the separated crystals subjected to suction. The residue was treated with active carbon and recrystallized two times from acetic acid ethyl ester to yield 3.0 g of dye crystals (mp: l92- 194C, k 436 mu.

Other dyes can be synthesized readily by those skilled in the art with a synthetis method similar to the process as mentioned above merely by varying the starting materials.

The sensitizing dyes used in this invention can spectrally sensitize silver halide photographic emulsions and are especially effective to expand the sensitivity region ol gclatino-silver halide photographic emulsions.

They can also sensitize silver halide photographic emulsions which contain gelatin derivatives such as acetylated gelatin, phthalated gelatin, etc., hydrophilic colloids other than gelatin derivatives such as cellulose 5 derivatives (e.g., carboxymethyl cellulose, cellulose ether, partially hydrolyzed cellulose), polyvinyl alcohol, polyvinyl pyrrolidone, copolymers of maleic anhydride and phthalic acid and other synthetic or natural hydrophilic high molecular substances. Generally 10 speaking, any photographic binder can be used with success in the present invention.

As the silver halide photographic emulsion used in this invention, various kinds of silver salts such as silver bromide, silver iodobromide, silver chlorobromide, silver chloroidobromide, etc., can be used and especially silver bromide and silver iodobromide emulsions are used effectively. So long as the silver halide is photosensitive, it can be used with success in the present inen ion.

However, most preferred emulsions are those wherein the weight ratio of silver halide to binder is from about 4 about 1 to about 1 about 4.

The present invention is very effective when the silver halide used has particles which are normal or ultra linc grains (for example, those with an average particle diameter in number, measured by the projected area method, of less than about 0.1 u). The effect of this invention is more remarkable for the ultra fine grains.

For the preparation of sensitized silver halide photographic emulsions according to this invention, the sensitizing dye can be dissolved in a suitable solvent such as methanol, ethanol, methylcellosolve, etc., and added as solution to a silver halide photographic emulsion in the manner commonly used in this art. Suitable solvents are easily selected, the primary considerations entering into the selection of the solvent being that the solvent is easy to handle, inexpensive, does not harm photographic properties and is not injurious to the health. Organic solvents miscible with water are generally used.

The amount of sensitizing dye contained in a silver halide photographic emulsion can be varied within, for example, a range of about 1 X 10 to about 1 X 10 mol/mol of silver. Especially excellent results are obtained when the amount of sensitizing dye is about 5.8 X 10 mols/mol of silver.

Additionally, any known sensitizing dye may be added to the silver halide photographic emulsion according to this invention.

ln the preparation of a silver halide photographic emulsion according to this invention, any commonly used chemical sensitizer, toner, film-hardener, antifogging agent, surface active agent, thickener, plasticizer, lubricant, development accelerator, color coupler, UV-absorbent, irradiation inhibitor, matting agent, etc., may be added at proportions as are common in this art using any general addition technique.

The silver halide photographic emulsion according to this invention may be coated by any technique commonly used in the art onto a suitable substrate such as, for example, glass, a film of cellulose derivatives (triacetyl cellulose, etc.), a film ofa synthetic resin (polyethylene terephthalate, etc.), baryta paper, a resin-coated paper, synthetic paper and the like. In short, any photographic substrate can be used with success in the present invention.

Several examples of preferred embodiments of the present invention are given below.

A given amount (8 ml per 100 g of emulsion) of a methanolic solution (1/l,000 mol of dye per liter of methanolic solution) of one of the above mentioned sensitizing dyes used in this invention was individually added to 100 g of a gelatino silver iodobromide emulsion ((I: Br ratio 3:97 molar): ratio of silver halide:- binder 1:2 (weight); silver halide particle size of 0.08 mu), which was prepared in a known method. 7 ml of the resulting silver halide photographic emulsion was coated on a glass plate of cabinet size and dried to prepare a sample.

The sample was exposed through a No. 2 filter (Fuji Photo Co., through which light of a wave length longer than 450 mu passes) with an optical wedge by means of a tungsten lamp having a color temperature of 2,666K (2,000 lux, 20 seconds) and then developed at 20C for 5 min with a liquid developer of the following formulation:

Metol Sodium sulfite Hydroquinone Anhydrous sodium carbonate Potassium bromide 5 Water to make l liter.

In table 1, the spectral sensitivity, fog and maximum sensitization are shown for sensitizing dyes according to this invention as well as control sensitizing dyes. FIG. 1 shows the spectral sensitivity curve of dye (I) of this invention and of control dye A based upon the data derived in this example.

TABLE 1 Ex. Dye Amount of Dye Sensitiza- Fog Maximum No. added tion sensiti- (n1ol/mol-Ag) degree zation l l 5.8 X I" 800 0.04 480 my. 2 2 do. 400 0.04 475-480 mu 3 3 do. 750 0.04 480 mu 4 4 do. 350 0.04 475 mp. 5 5 do. 600 0.04 480 my. 6 6 do. 650 0.04 480 mu A do. 100 0.04 458 m l Con- B do. I 0.04 465-470 my. trol C do. 110 0.04 465 mp.

D do. 120 0.04 460 mg The spectral sensitivity is shown under the heading Sensitization Degree" as a specific sensitivity where the sensitivity of sensitizing dye A used as a control is set as 100.

The chemical structures of the sensitizidng dyes which were used as controls are as follows:

O COOCH 5 C =CH-CH=C N & (300C 14 2 5 t Cl N CN D m =CHCH=C Cl lq COOC H As is seen from the data in Table l, the emulsions containing the sensitizing dyes according to this inven tion have a sensitization maximum within the range of 460 490 mu and show little fog and high sensitivity as compared with the controls.

FIG. ll shows the spectral sensitivity curves of silver halide photographic emulsions which contain novel sensitizing dye (I) used in this invention and control sensitizing dye A, respectively.

As is seen from FIG. 1, sensitizing dye (I) used in this invention forms the J-aggregate and has a high spectral sensitivity at 460 490 m,u.

While the invention has been described in detail and with reference to specific embodiments thereof, it will be apparent to one skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope thereof.

What is claimed is:

l. A silver halide photographic emulsion characterized by containing at least one sensitizing dye represented by the following general formula:

wherein R and R each represents an alkyl or substituted alkyl radical selected from the group consisting of carboxyalkyl, alkoxyalkyl, hydroxyalkyl, acyloxyalkyl, sulfoalkyl and aralkyl, and R and R each represents an acyl or alkoxycarbonyl radical.

2. A silver halide photographic emulsion as claimed in claim 1 wherein R and R are unsubstituted alkyl.

3. A silver halide photographic emulsion as claimed in claim 1, wherein any alkyl moiety has up to 4 carbon atoms, with the exception of the alkyl moiety in the alkoxy group which has up to 3 carbon atoms.

4. A silver halide photographic emulsion as claimed in claim 3 wherein said acyl group is an aromatic acyl or aliphatic acyl group having up to 3 carbon atoms.

5. A silver ahalide photographic emulsion as claimed in claim 4 wherein said aromatic acyl group is benzoyl.

6. A silver halide photographic emulsion as claimed in claim 4 wherein said silver halide has an average particle diameter, in number, of less than about 0.1 u.

7. A silver halide photographic emulsion as claimed in claim I wherein said sensitizing dye is present in an amount ol'l'rom about l X H) to about I X l0 mollmololsilvcr. k

Claims (7)

1. A SILVER HALIDE PHOTOGRAPHIC EMULSION CHARACTERIZED BY CONTAINING AT LEAST ONE SENSTIZING DYE REPRESENTED BY THE FOLLOWING GENERAL FORMULA:

2. A silver halide photographic emulsion as claimed in claim 1 wherein R1 and R2 are unsubstituted alkyl.

3. A silver halide photographic emulsion as claimed in claim 1, wherein any alkyl moiety has up to 4 carbon atoms, with the exception of the alkyl moiety in the alkoxy group which has up to 3 carbon atoms.

4. A silver halide photographic emulsion as claimed in claim 3 wherein said acyl group is an aromatic acyl or aliphatic acyl group having up to 3 carbon atoms.

5. A silver ahalide photographic emulsion as claimed in claim 4 wherein said aromatic acyl group is benzoyl.

6. A silver halide photographic emulsion as claimed in claim 4 wherein said silver halide has an average particle diameter, in number, of less than about 0.1 Mu .

7. A silver halide photographic emulsion as claimed in claim 1 wherein said sensitizing dye is present in an amount of from about 1 X 10 3 to about 1 X 10 4 mol/mol of silver.

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