US 3915714 A
The light-sensitivity of a photographic material comprising at least one supported silver salt emulsion layer is improved by the addition of a water-soluble phosphoric acid amide as definded below.
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Description (OCR text may contain errors)
United States Patent [1 1 Saleck et al.
[4 1 Oct. 28, 1975 1 SILVER I'IALIDE EMULSION CONTAINING A PHOSPI-IORIC ACID AMIDE  Inventors: Wilhelm Saleck, Schildgen;
Wolfgang Himmelmann, Opladen; Karl-Erwin Schnalke; Gerhard Balle, both of Cologne, all of Germany  Assignee: Agfa-Gevaert Aktiengesellschaft,
Leverkusen, Germany  Filed: May 7, 1974 ] Appl. No.: 467,819
Related US. Application Data  Continuation of Ser. No. 309,279, Nov. 24, 1972,
 Foreign Application Priority Data Nov. 30, 1971 Germany 2159379 Primary ExaminerWon I-l. Louie, Jr. Attorney, Agent, or Firm-Connolly and Hutz [5 7] ABSTRACT The light-sensitivity of a photographic material comprising at least one supported silver salt emulsion layer is improved by the addition of a water-soluble phosphoric acid amide as definded below.
2 Claims, No Drawings SILVER HALIDE EMULSION CONTAINING A PHOSPHORIC ACID AMIDE This application is a continuation of the copending, U.S. Application Serial No. 309,279, filed November 24, 1972, entitled Photographic Silver Salt Emulsion With Increased Sensitivity.
This invention relates to a photographic silver salt emulsion with increased sensitivity which is achieved by the addition of phosphoric acid amides.
The sensitivity to light of a photographic silver salt emulsion can be influenced in two ways. Firstly, it can be increased by suitable choice of the precipitation conditions and of the so-called physical ripening. In practice, the possibility of increasing the sensitivity in this way is limited by the fact that the increase in sensitivity is accompanied by an increase of the grain size, which deleteriously effect the quality of the final image. It is therefore desired to obtain silver salt emulsions with a very high light-sensitivity but-fine grain.
Secondly, the sensitivity of photographic emulsions can be increased by chemical methods by adding compounds which are generally known as chemical sensitizers. In principle, these compounds could be added at any stage of the preparation of the emulsion, e.g. as ripening additives before chemical ripening or to the finished casting solution after chemical ripening. Ripening agents are e.g. noble metal salts, particularly gold salts, and sulfur compoundssuch as thiosulfates or organic and particularly heterocylic sulfur compounds. A disadvantage of the chemical sensitization method is that the increase in sensitivity is accompanied by an increased tendency of the emulsion to form an uniform fog which is capable of being developed. For this reason, very active chemical sensitizers such as compounds with an onium structure, e.g. quaternary ammonium or phosphonium salts or ternary sulfonium salts or polyalkylene oxides and polyalkylene oxide derivatives can only be added to the finished casting solution after chemical ripening. If such substances were added before chemical ripening, the photographic silver salt emulsions would be so heavily fogged that they would be practically useless.
None of the known chemical sensitizers adequately satisfies practical requirements, either because the increase in sensitivity achieved is insufficient or because concomitant fogging prevents application of the sensitizer.
It is among the objects of the present invention to provide new chemical sensitizers which do not have the above disadvantages and which increase the lightsensitivity of photographic silver salt emulsions, in particularly of photographic silver halide emulsions, without unwanted fogging.
We now have found a photographic material containing at least one silver salt emulsion layer which contains, as chemical sensitizer, a water-soluble phosphoric acid amide of the following formula:
R is l) a hydrogen atom, (2) a saturated or olefinically unsaturated aliphatic group, preferably an alkyl group and particularly an alkyl group containing 1-3 carbon atoms, (3) an aryl group, in particular a phenyl group, which may be substituted, e.g. with an alkyl or alkoxy group, both of which preferably contain up to 3 carbon atoms, a carboxyl, sulfo, sulfonamido, alkyl sulfonyl group, a halogen atom such as fluorine, chlorine or bromine or a nitrile group, (4) cycloalkyl such as a cyclopentyl or cyclohexyl group or (5) an acyl group, in particular acyl groups which are derived from organic sulfonic acids, such as alkyl sulfonyl with alkyl groups which preferably contain up to 5 carbon atoms or phenyl sulfonyl in which the phenyl ring may contain additional substituents, e.g. saturated or olefinically unsaturated aliphatic groups which preferably contain up to 3 carbon atoms and which may themselves contain substituents such as halogen, e.g. chlorine or bromine, alkoxy, phenoicy, sulfo groups or carboxyl groups; other suitable substituents on the phenyl ring in addition to those mentioned above are e.g. amino groups, alkylamino groups, diester groups of sulfonylimido phosphoric acid or acylated amino groups, in particular with radicals of saturated or. unsaturated aliphatic carboxylic acids which preferably contain up to 5 carbon atoms, v
R is (l) a hydrogen atom, (2) a saturated or olefinically unsaturated aliphatic group, preferably an alkyl group and in particular an alkyl group with 1-3 carbon atoms, (3) aryl, in particular a phenyl group, which may be substituted, e.g. with alkyl or alkoxy groups which preferably contain up to 3 carbon atoms, carboxyl, sulfo, sulfonamido or alkyl sulfonyl groupsor halogen such as fluorine, chlorine or bromine or nitrile, or (4) a cycloalkyl group, such as a cyclopentyl or cyclohexyl group;
R is (l) a saturated or olefinically unsaturated aliphatic group preferably containing up to .5 carbon atoms, in particular an alkyl group, (2) an aryl group, in particular a phenyl group, which may be substituted as indicated for R, or (3) cycloalkyl, in particular a cyclohexyl or cyclopentyl group.
In particular preferred are compounds of the following formula: 5
R is (l) saturated or olefinically unsaturated alkyl having preferably up to 3 carbon atoms which may be substituted with halogen such as chlorine or bromine, alkoxy having preferably up to 3 carbon atoms, phenoxy, sulfo or carboxyl, (2) amino, (3) alkylamino, (4) acylated amino groups wherein the acyl radical is preferably derived from a saturated or olefinically unsaturated aliphatic carboxylic acids having preferably up to 5 carbon atoms, the acyl group may be derived from a polymeric aliphatic acid such as polyacrylic acid or polymethacrylic acid or copolymers of acrylic or methacrylic acid preferably with derivatives of these acids such as esters in particular with lower aliphatic alcohols having up to 5 carbon atoms, nitrils or amides wherein the amid groups may be substituted e.g. with ll \SOZNHHOR), groups or sulfo or sulfonamido wherein the amido group may be substituted, for example, with The following are examples of suitable compounds:
Copolymer of 50 Butylacrylate It is evident from the above table that the phosphoric acid amides used according to the invention may be either monomeric compounds or polymers. In the case of polymeric compounds, it is advantageous if the polymer contains at least 20 mol-% of active phosphoric acid amide units.
The molecular weight of the polymeric compound is in itself not critical provided that the polymer remains sufficiently soluble in water. The same applies to comonomers. The chemical structure of the comonomers is not critical provided only that the photographic properties of the emulsion are not deleteriously affected by the comonomers and that the polymer remains sufficiently soluble in water. Suitable olefinically unsaturated comonomers are e.g. unsaturated monoand dicarboxylic acids, e.g. acrylic acid and methacrylic acid or derivatives thereof such as esters, amides and nitriles, as well as crotonic acid, maleic acid, fumaric acid, itaconic acid as well as derivatives of these acids, in particular their semi-esters and semi-amides, as well as vinyl compounds such as vinyl ether, in particular those which contain aliphatic ether groups with up to 5 carbon atoms, e.g. vinylethyl ether or vinyl isobutyl ether; furthermore, vinyl esters, in particular vinyl esters of aliphatic carboxylic acids with up to 3 carbon atoms, e.g. vinyl acetate or vinyl chloroacetate, and in addition vinyl ketones such as vinylethyl ketone. A small percentage of hydrophobic comonomers such as olefines, e.g. ethylene, propylene or butylene, may of course also be present so long as the copolymer remains sufficiently water-soluble.
The preparation of the compounds used according to the invention is already known. Reference may be made to the following publications:
A. v. KIRSANOV and N. L. EGOROVA, z.ob.-
Chim. 25, 187 (1955) A. V. KIRSANOV and V. l. SHEVCHENKO,
Z.ob6.Chim. 24, 882 (1954) A. V. KIRSANOV and V. I. SHEVCHENKO,
Z.obsc.Chim. 24, 1980 (1954). Phosphoric acid diester (N-acrylsulfonylamides), for example, are prepared as follows:
1st stage Sulfonylimino-phosphoric acid trichloride 2nd stage Phosphoric acid (N-sulfonylamide) dichloride 0.01 mol of sulfonylimino-phosphoric acid trichloride are dissolved in benzene and mixed with 0.01 mol of anhydrous formic acid. Carbon monoxide and hydrogen chloride start to evolve after some time. The reaction mixture is left to stand at room temperature for -12 hours and then suction filtered.
3rd stage Phosphoric acid diester 0.3 mol of pyridine or triethylamine is slowly added dropwise with cooling at 010C to a solution of 0.1 mol of phosphoric acid (N-sulfonylamide) dichloride in an alcohol. Stirring is continued for half an hour at room temperature after all the pyridine or triethylamine has been added and the solution is then concentrated by evaporation. 100 ml of water are added and the reaction mixture is slowly acidified to pH 2-3 with hydrochloric acid whilst cooling. The reaction product which crystallizes is washed with water.
The photographic silver salt emulsions which are chemically sensitized in accordance with the invention are prepared by the usual methods. Preparation of these emulsions comprises the following steps:
1. Precipitation of the silver salts, in particular silver halides, in the presence of a protective colloid and physical ripening;
2. coagulation or flocculation of the emulsion and washing to remove the water-soluble salts formed on precipitation, and
3. redispersion of the washed emulsion and chemical ripening.
The chemical sensitizer according to the invention are added to the photographic silver salt emulsion before chemical ripening, preferably at the stage of precipitation. The quantity required to he added depends .on the effect desired and can be determined in the usual manner by a few simple tests. Quantities of 1-50 g, based on g of gelatin originally used for the emulsion, are generally sufficient. Based on the amount of silver halide to be precipitated, the amount required is ISO mg to 8 g, preferably 300 mg to 4 g, per mol of silver salt.
The substances used according to the invention are preferably added in the form of their aqueous solutions. The concentration of the substances in this solution is not critical and may vary within wide limits. The phosphoric acid amides must be water-soluble to such an extent that it is possible to prepare an aqueous solution containing a sufficient quantity of active substance. It is sufficient, for example, to use a l5% solution. In the case of very soluble substances, of course, a more concentrated solution may be used. The solutions are generally dissolved at a pH of about 7 but the pH of the solution may be kept slightly acid, e.g. at pH values of between 5 and 7, or in the case of so-called ammonia emulsions the pH of the solution may be between 5 and The substances according to the invention may be used in any silver salt emulsions, preferably in silver halide emulsions. Suitable silver halides are silver chloride, silver bromide or mixtures of silver chloride and silver bromide, optionally with a small silver iodide content of up to 10 mol-%. The silver halides may be dispersed in the usual hydrophilic binders, for example in carboxymethyl cellulose, polyvinyl alcohol, polyvinyl pyrrolidone, alginic acid and its salts, esters or amides or proteins, preferably gelatin.
The emulsions may also contain other chemical sensitizers, e.g. quaternary ammonium and phosphonium salts or ternary sulfonium salts or reducing agents such as tin-ll-salts, polyamines such as diethylene triamine or sulfur compounds as described in US. Pat. Specifi cation No. 1,574,944. In addition, the given emulsions may contain salts of noble metals such as ruthenium, rhodium, palladium, iridium, platinum or gold for chemical sensitization, as described in the article by R. KOSLOWSKY, Z.Wiss.Phot. 46, 65-72 (1951). The emulsions may also contain polyalkylene oxides or polyalkylene oxide derivatives as development accelerators or chemical sensitizers. An additional increase in sensitivity is thereby achieved.
The emulsions may also be optically sensitized, e.g. with the usual polymethine dyes such as neutrocyanines, basic or acid carbocyanines, rhodacyanines, hemicyanines, styryl dyes, oxonoles and the like. Sensitizers of this kind have been described in the work by F. M. HAMER The Cyanine Dyes and related Compounds, lnterscience Publishers, a division of John Wiley and Sons, New York (1964).
The emulsions may contain the usual stabilizers, e.g. homopolar or salt type compounds of mercury which contain aromatic or heterocyclic rings (for example mercaptotriazoles), simple mercury salts, sulfonium mercury double salts and other mercury compounds. Other suitable stabilizers are azaindenes, especially tetraor pentaazaindenes and particularly those which are substituted with hydroxyl or amino groups. Compounds of this kind have been described in the article by BlRR, Z.Wiss.Phot. 47, 2-58 (1952). Other suitable stabilizers are e.g. heterocyclic mercapto compounds such as phenyl mercaptotetrazole, quaternary benzothiazole derivatives, benzotriazole and the like.
The emulsions may be hardened in the usual manner, for example with formaldehyde or halogenated aldehydes which contain a carboxyl group, such as mucobromic acid, diketones, methane sulfonic acid esters, dialdehydes and the like or polyfunctional triazine derivatives such as tris-acryloyl-hexahydrotriazine or halogenated or alkoxysubstituted hexahydrotriazine derivatives.
The substances according to the invention exert their advantageous effect not only in black and white emulsions but also in the production of color photographic images. They are readily compatible with the usual color couplers. The phosphoric acid amides may also be used in direct positive emulsions, e.g. those with a composite grain structure according to French Pat. Specification No. 1,585,791.
They are also suitable for emulsions used in the silver dye bleaching process or dye diffusion process.
The phosphoric acid amides are particularly effective in those silver salt emulsions which are precipitated in the presence of silica sols. The preparation of such emulsions has been described in U.S. Pat. Specification According to another preferred embodiment, the phosphoric acid amides are used in combination with polymers which contain disulfonimide groups. Compounds of this kind have been described in German Pat. Specification No. 1,089,548 and in U.S. Pat. Specification No. 3,052,656. The polymeric disulfonimides are added before chemical ripening, preferably at the stage of precipitation or flocculation. The concentration of the disulfonimides may vary within wide limits. Quantities of 1 to 10%, based on the original amount of gelatin, have been found to be sufficient.
EXAMPLE 1 SAMPLE l:
A neutral silver iodobromide gelatin emulsion containing 6 mol-% of silver iodide (average particle size 0.9 u) is precipitated. 100 g of gelatin are used for precipitating 1 kg of silver halide. After precipitation and physical ripening of the silver halide, the emulsion is cooled to 35C. It is flocculated in the usual manner with polystyrene sulfonic acid and acidified to pH 3.0 with 25% sulfuric acid. The flocculate is left to precipitate and the supernatant solution is removed. The flocculate is then washed twice with 20 litres of water by agitating the flocculate for minutes. After the final removal of the supernatant water, the flocculate is dissolved in a suitable quantity of water and gelatin at pH 7 and 40C and treated with gold-Ill chloride and sodium thiosulfate as ripening additives and then ripened at a ripening temperature of 40C after the pAg value has been adjusted to 8.9.
SAMPLE 2 The emulsion is prepared in the same manner but during precipitation, 50 ml of a 7% aqueous solution of compound I are added to the given gelatin/alkali metal halide solution.
Samples 2-17 are prepared in a similar manner by the addition of the same amount of compounds 1-16 at the precipitation stage. All the samples are then cast on a cellulose acetate support after the addition of the following additives per kg of emulsion, viz.: ml of a 5% aqueous solution of saponin as wetting agent, 10 ml of a 10% aqueous solution of formaldehyde as hardener and ml ofa 1% methanolic solution of 4-hydroxy-6- methyl-l ,3,3a,7-tetraazaindene as stabilizer. After development in a conventional sensitometer behind a step wedge and development (7 and 16 minutes at 20C) in a developer of the following composition:
Sodium sulfite anhydrous 70.0 g borax 7.0 g hydroquinone 3.5 g pMonomethylaminophenol sulfate 3.5 g sodium citrate 7.0 g potassium bromide 0.4 g
made up to 1 litre with water the results are assessed sensitometrically. From the following table it will be seen that emulsions 2-17 are more sensitive than the comparison emulsion l.
7 minutes development 16 minutes development Sample Sensi- F Fog Sensi- F Fog tivity tivity 1 Typ 0.60 0.16 Typ 0,90 0,21 2 2 0.60 0.12 1 0.95 0,25 3 1 0.60 0,14 1,5" 0,85 0.23 4 +1,5 0,70 0.18 1 0,85 0.19 5 2 0.70 0.10 1.5 0.90 0.22 6 2 0.70 0,19 1 0,90 0.25 7 2 0,70 0.13 1 0.90 0,22 8 15 0.65 0.18 1 0,80 0.28 9 2 0,70 0,10 1 0,95 0.22 10 1.5 0.75 0.12 1 0.90 0.20 11 1 0.80 0,16 15 0.90 0,24 12 +1,5 0.75 0.12 1" 0.90 0.20 13 1 0,80 0,16 15 0.90 0,24 14 1 0.65 0.10 1 0,75 0.19 15 +1,5 0,70 0.11 1 0,85 0.21 16 15 0,65 0.13 1.5 0,80 0.21 17 2 0.70 0.16 1.5" 0.90 0,24
3 l shutter stop EXAMPLE 2 Samples 1 and 11 of Example 1 are compared with emulsion 18 which was prepared in the same way as emulsion 11 but with the addition of 20 ml of a 20% aqueous solution of a polydisulfonimide of the formula at the precipitation stage.
All three emulsions are then processed as described R R" in Example 1. Nfi
in which Sensi- R is (1) an alkyl group having up to 3 carbon atoms, Sample tivity I Fog Sensitivity l Fog (2) a phenyl group, (3) a cycloalkyl or 4 a Stand phenylsulfonyl group;
1 dard 0.60 0.15 Standard 0.90 0.25 to R2 is a y g atom, an alkyl group having 11 15 0.65 0.13 15 0. up to 3 carbon atoms, (3) a phenyl group or (4) cy- 18 2.s 0.65 0.13 2.5" 0.95 0.23
cloalkyl, 3 l shutter stop R3 is 'O'R4 or R4 EXAMPLE 3 R is l an alkyl group having up to 5 carbon atoms, SAM 1 20 (2) phenyl or (3) cycloalkyl; E l i 1 of E l 1 i d f comparison said amide being in a quantity sufficient to sensitize the material.
2. A process for the preparation of photographic sil- SAMPLE 2 ver halide emulsions by precipitation of the silver halide, physical ripening, flocculation or solidification and chemical ripening, wherein the improvement comprises adding to the emulsion during precipitation a phosphoric acid amide of the following formula:
The emulsion of sample 11 of Example 1 is used.
SAMPLE 3 The emulsion of sample 11 of Example 1 is used but at the precipitation stage of the alkali metal halide solution, 200 ml of a 30% silicic acid sol (pH 8.3, particle RI size about 14 nm, stabilized with NaOH) are added. N-P
The emulsion is then processed as described in Example l. The results of the sensitometric measurements are summarized in the table below.
R is 1) an alkyl group having up to 3 carbon atoms,
(2) a phenyl group, (3) cycloalkyl or (4) a phenyl- 7 minutes development 16 minutes development time .1"... Sfllfonyl group, Sample Sensi- I Fog S ensi- I Fog R 1s l) a hydrogen atom, (2) an alkyl group havlng up to 3 carbon atoms, (3) a phenyl group or (4) cy- 1 Standard 0.60 0.16 Standard 0.90 0.21 cloalkyl; 2 2 0.70 0.10 +1" 0.95 0.22 a 4 3 3 0.70 0.12 1.s 1.00 0.22 R o R R2 3 l shutter stop 4 We claim: R
1. A photographic material comprising at least one R4 is an alkyl g p having "P m 5 carbon atoms, supported silver halide emulsion layer which contains p y y y -a water-soluble phosphoric acid amide added during said amide being in a quantity sufficient to sensitize the precipitation of the emulsion, said amide having the material. following formula: