US3615528A

US3615528A - Photographic silver halide emulsion having an increased sensitivity and reduced fogging

Info

Publication number: US3615528A
Application number: US883606A
Authority: US
Inventors: Harald Huckstadt; Wilhelm Saleck; August Randolph; Franz Moll; Anita Von Koenig
Original assignee: Agfa Gevaert AG
Current assignee: Agfa Gevaert AG
Priority date: 1968-12-23
Filing date: 1969-12-09
Publication date: 1971-10-26
Anticipated expiration: 1988-10-26
Also published as: DE1816570A1; GB1264562A; JPS4926135B1; CH544323A; BE746769A; FR2026968A1; CA936037A

Abstract

The sensitivity of light-sensitive photographic silver halide emulsions can be increased and the fogging can be decreased if the chemical ripening of that emulsions is performed in the presence of mercapto alkyl quaternary salts or acetothioalkyl quaternary salts of the following formula WHEREIN R represents alkyl with up to six carbon atoms; two R radicals of the same nitrogen can be combined to form a heterocyclic ring; R'' represents alkyl with up to six carbon atoms, which can be substituted, or an aralkyl group; R'''' represent H or -CO-CH3; n is one to six; and X is any anion.

Description

United States Patent [72] Inventors I-larald Huckstadt Cologne; Wilhelm Saleck, Schildgen; August Randolph, Leverkusen; Franz Moll, Leverkusen; Anita Von Koenig, Leverkusen, all of Germany [21] Appl. No. 883,606

[22] Filed Dec. 9, 1969 [45] Patented Oct. 26, 1971 [73] Assignee Agta-Gevaert Aktiengesellschalt Leve'rltusen, Germany [32] Priority Dec. 23, 1968 [33] Germany [54] PHOTOGRAPHIC SILVER HALIDE EMULSION HAVING AN INCREASED SENSITIVITY AND REDUCED FOGGING 11 Claims, No Drawings [52] [1.8. 96/663, 96/107,96/109 [51] Int. Cl. G03c 5/24, G030 1/28,G03c 1/34 [50] Field of Search 96/663,

[56] References Cited UNl'l'ED STATES PATENTS 3,453,281 7/1969 Burnessetal 3,471,296 10/1969 l-luckstadtetal Primary Examiner-Norman G. Torchin Assistant Examiner-Richard E. Fichter Attorney-Connolly and Hutz ABSTRACT: The sensitivity of light-sensitive photographic silver halide emulsions can be increased and the fogging can be decreased if the chemical ripening of that emulsions is performed in the presence of mercapto alkyl quaternary salts or acetothioalkyl quaternary salts of the following formula PI-IOTOGRAPIIIC SILVER IIALIDE EMULSION HAVING AN INCREASED SENSITIVITY AND REDUCED FOGGING The present invention relates to a process for increasing the sensitivity of photographic silver halide emulsions together with reduced fogging by the addition of mercaptoalkyl quaternary salts or acetothioalkyl quaternary salts.

The sensitivity of a photographic emulsion can be effected in two ways. First the sensitivity can be increased during the preparation of the emulsion at the stage of so-called chemical ripening, by increasing the ripening time or by the addition of suitable compounds such as thiosulfate or other additives which usually contain sulfur. The other method of increasing the sensitivity of photographic emulsion consists of adding socalled development accelerators or chemical sensitizers. These are usually added to the finished ripened emulsion.

Development accelerators which have been described for this purpose include, e.g., compounds which have an onium structure (such as quaternary ammonium and phosphonium and ternary sulfonium salts), and also polyalkylene oxides and polyalkylene oxide derivatives are very frequently employed.

Nearly all the additives, however, have the unfavorable side effect of increasing the fogging of the emulsion. In order to counteract the increase in fogging which may occur not only during storage in the heating cupboard but also in the fresh sample, it is in most cases necessary to increase the quantity of stabilizer. However, it is a property of most stabilizers that they reduce the sensitivity when used in substantial quantities.

In this way the effect of thedevelopment accelerator may be impaired.

There is, therefore, an urgent need to find development accelerators or ripening agents which do not bring about any additional increase in fogging and there is also an urgent need to find stabilizers which do not reduce the sensitivity of the photographic emulsion. It is desirable to find substances which would both increase the sensitivity of the photographic emulsion and which would stabilize the fogging.

This is the object of the present invention.

It has now been found that silver halide emulsions which have increased sensitivity and reduced fogging are obtained by adding to the emulsions, in the course of after ripening, mercaptoalkyl quaternary salts or acetothioalkyl quaternary salts of the following general formula:

wherein represents:

R an alkyl group having up to six carbon atoms; two R radicals attached to the same nitrogen atom may, with this nitrogen atom, form a saturated five-, six-, or sevenmembered heterocyclic ring, which may contain further hereto atoms, e.g. a piperidine, morpholine, thiomorpholine, pyrrolidine, or hexamethyleneimine ring or an unsaturated heterocyclic ring such as pyridine, in the latter case R is not present;

R an alkyl group having up to six carbon atoms which may be substituted, for example haloalkyl, hydroxyalkyl, cyanoalkyl, carboxyalkyl or an aralkyl group such as benzyl or phenylethyl, the aryl radical of which may be substituted in turn, e.g. with alkyl, alkoxy, halogen, and amino groups;

n represents an integer of from 1 to 6;

X any anion such as chloride or bromide, tosylate, perchlorate or sulfate, when R contains a carboxylate group. X is absent.

The following formula are given for the purpose of illustrating the compounds more fully but are not intended to restrict the scope of the invention:

The compounds according to the invention are prepared according to the following reaction scheme:

These reactions have been described in respect of open chained quaternary salts in Archiv der Pharmazie 293, 55-57 (1960); and in Liebig's Ann. 630, 105-155 (1960). The cyclic salts are prepared in analogous manner.

The compounds according to the invention show their advantageous effect particularly clearly when they are used in place of thiosulfate or other conventional sulfur ripening agents for chemical ripening. Apart from the increase in sensitivity described in the example, the considerable reduced fogging in the samples is very noticeable. This reduction in fogging can be seen not only in fresh samples but also after storage in a heating cupboard.

The advantage of using the compounds according to the invention lies not so much in the increase in sensitivity, which is to be regarded as only average, but in the combination of increase in sensitivity with reduction in fogging which enables other ingredients, which may possibly increase the fogging to be added to the emulsion without the total fogging then being too great.

Emulsion prepared with the substances according to the invention will, therefore, be particularly suitable for use in combination with other development accelerators. The reduced fogging will also be very important in the preparation of color emulsions, since these are normally particularly susceptible to fogging.

The cause for the above-mentioned effect of mercapto quaternary salts and acetothioquaternary salts isstill not clear. Their mode of action is very similar to that of disulfide quater nary salts (see U.S. Pat. Application Ser. No. 886,039, filed Dec. 17, 1969 (A-G 442) except that they have no positive effect when added as casting additives to the finished ripened emulsion, although they do not reduce the sensitivity nor cause fogging as often can be observed when mercapto compounds are added to an emulsion.

The compounds do not have any advantageous effect when used in the developer.

It is desirable to add the compounds according to the invention to the photographic emulsion at the start of chemical ripening. The quantity added depends on the emulsion used in a particular case and can easily be determined by those skilled in the art at any time by the usual tests.

A quantity of 0.001 to 0.3g. per mol of silver halide will generally be sufficient.

The substances according to the invention can be used in any silver halide emulsions. Suitable silver halides are silver chloride, silver bromide or mixtures thereof, optionally with a small silver iodide content of up to 10 mols percent. Silver halides may be dispersed in the usual hydropholic compounds, for example carboxymethylcellulose, polyvinyl alcohol, polyvinyl pyrrolidone, alginic acid and its salts, esters or amides or preferable gelatin.

The emulsions may also contain other chemical sensitizers, e.g. quaternary ammonium and phosphonium salts and ternary sulfonium salts, reducing agents as stannous salts, polyamines such as diethylene triamine or sulfur compounds as described in U.S. Pat. No. 1,574,844. The above-mentioned emulsions may also 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 be optically sensitized, e.g. with the usual polymethine dyes such as neutrocyanines, basic or acid carbocyanines, rhodacyanines, hemicyanines, styryl dyes, and oxonols. Sensitizers of this type have been described in the book by F. M. Hamer The Cyanine Dyes and Related Compounds" 1964). i

The emulsion may contain the usual stabilizers, e.g. homopolar or salt-type compounds of mercury containing aromatic or heterocyclic rings (for example of mercaptotrazoles), simple mercury salts, sulfonium mercury double salts and other mercury compounds. Azaindenes, especially tetraor pentaazaindenes, and in particular those which are substituted with hydroxyl or amino groups, are also suitable for use as stabilizers. Compounds of this type are described in the article by Birr, Z. Wiss. Phot. 47, 2-58 (1952). Other suitable stabilizers include heterocyclic mercapto compounds, e.g. phenylmercapto tetrazole. quaternary benzothiazole derivatives and benzotriazole.

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, and dialdehydes.

The emulsions treated with the mercaptoalkyl and S-acetylthio-alkyl quaternarysalts according to the invention may also contain color couplers for the production of color photographic images.

EXAMPLE 1 A silver iodobromide emulsion containing 5 mols percent of silver iodide is prepared in the usual manner. For after-ripening, the pAg is adjusted to 8.9. the pH to 6.8. and the viscosity to 8 cp. Gold thiocyanate is then added and the emulsion is divided into 7 equal parts. The following additives are then added to the individual samples (the amounts given are based on 1 kg. of emulsion containing l30 g. of silver halide:

Sample A: Comparison sample without additive Sample B: 3.3 mg. ofCompound V Sample C: 3.3 mg. ofCompound Xlll Sample D: 7.0 mg. ofCompound lV Sample :3.3 mg. ofCompound XV Sample 3.3 mg. ofCompound VI Sample G: 3.3 mg. of a compound of the following formula (for comparison) The after-ripening is carried out to maximum sensitivity and the samples are made ready for casting by the addition of 600 mg. of saponin as wetting agent, 200 mg. of 4-hydroxy-6- methyl-l ,3,3a,7-tetraazaindene as stabilizer and 10 ml. ofa l0 percent aqueous solution of formaldehyde as hardener, per kg. ofemulsion.

The samples are then cast on cellulose acetate, exposed in a sensitometer behind a grey step wedge and developed for minutes in a developer of the following composition:

A difference of 3 represents a difference of one shutter stop.

A comparison of samples F and G shows that the mercapto quaternary salts are very similar in their effect to the disulfide quaternary salts, which is easily understandable on chemical grounds.

Example 2 An emulsion as in example 1 is divided into 8 equal parts.

The following substances are added per kg. of emulsion to the individual parts: Sample A: Comparison sample-without additive Sample B: 3.3 mg. ofCompound 1X Sample C: 3.3 mg. ofCompound Vlll Sample D: 3.3 mg. ofCompoundl Sample E: 3.3 mg. ofCompound 11 Sample F: 3.3 mg. ofCompound XVI Sample G: 3.3 mg. ofCompound XVll Sample 1-1: 3.3 mg. ofCompound XIV The samples are cast, exposed and developed as in example 1.

Table 2 Sample Sensitivity y fog log 3 days 60 A Blank 0.82 0.19 0.24 B +l.2 0.87 0.13 0.18 C +l.l 0.84 0.12 0.16 D +0.7 0.83 0.16 0.18 E +0.9" 0.86 0.15 0.18 F +l.0 0.85 0.12 0.15 O +l.l 0.84 0.12 0.16 H +0.9 0.86 0.13 0.16

LII

A difference of 3 represents a difference of one shutter stop.

We claim:

1. A light-sensitive photographic material having at least one silver halide emulsion layer which contains a compound ofthe following formula as ripening agent:

in which R represents an alkyl group having up to six carbon atoms; two R radicals attached to the same nitrogen atom may with the said nitrogen atom form a saturated five-, sixor seven-membered heterocyclic ring containing at least one hetero atom or an unsaturated heterocyclic ring, in the latter case R is not present;

R represents an alkyl group having up to six carbon atoms, which may be substituted or an aralkyl group, the aryl radicals of which may be substituted;

R" represents H or COCH n is an integer offrom l to 6;

X 9 is any anion; when R contains a carboxylate group, X e

is absent.

2. A light-sensitive photographic material according to claim 1, wherein the silver halide emulsion layer in addition contains color couplers.

3. A light-sensitive photographic material according to claim 1, which contains a compound of the following formula:

CH3 CH I 3CH CH CH;SH 0104 4. A light-sensitive photographic material according to claim 1, which contains a compound of the following formula:

5. A light-sensitive photographic material according to 6. A light-sensitive photographic material according to claim 1, which contains a compound of the following formula:

7. A light-sensitive photographic material according to claim 1, which contains a compound ofthe following formula:

8. A light-sensitive photographic material according to claim 1, which contains a compound of the following formula:

9. In the process for the production of black-and-white or 11. In the process for the preparation of photographic silver color images by developing an imagewise exposed light-sensihalide emulsions by precipitating the silver halide in the tive photographic material which comprises at least one silver presence of a protective colloid, washing and chemical ripenhalide emulsion layer, the improvement according to which ing the improvement according to which the chemical ripenthe development is carried out in the presence of a compound ing is carried out in the presence of a compound of the followof the following'formula: ing formula:

R represents an alkyl group having up to six carbon atoms;

two R radicals attached to the same nitrogen atom may with the said nitrogen atom form a saturated five-, sixor R represents an alkyl group having up to six carbon atoms; two R radicals attached to the same nitrogen atom may seven-membered heterocyclic ring containing at least one with the Said t g atom form a 531i ated -i hetero atom or an unsaturated heterocyclic ring, in the seven-membered heterocyclic ring containing at least one latter case R is notpresent; hetero atom or an unsaturated heterocyclic ring, in the R represents an alkyl group having up to six carbon atoms, ialtef Case is not P which y Substituted alkyl group, the y R represents an alkyl group having up to six carbon atoms, :adlcais Ofwhlch y be substituted; which may be substituted or an aralkyl group, the aryl rePfesems H :1 radicals ofwhich may be substituted; n is an integer offrom l to 6; R t H CO CH X e is any anion; when R contains a carboxylate group, X repfesfll s or is absent n is an integer offrom l to 6; 10. The process according to claim 9, wherein the exposed is y anion; when Contains a yiate gro p, X photographic material is developed with a color'forming i5 absemdeveloper in the presence of color couplers.

Claims

2. A light-sensitive photographic material according to claim 1, wherein the silver halide emulsion layer in addition contains color couplers.
3. A light-sensitive photographic material according to claim 1, which contains a compound of the following formula:
4. A light-sensitive photographic material according to claim 1, which contains a compound of the following formula:
5. A light-sensitive photographic material according to claim 1, which contains a compound of the following formula:
6. A light-sensitive photographic material according to claim 1, which contains a compound of the following formula:
7. A light-sensitive photographic material according to claim 1, which contains a compound of the following formula:
8. A light-sensitive photographic material according to claim 1, which contains a compound of the following formula:
9. In the process for the production of black-and-white or color images by developing an imagewise exposed light-sensitive photographic material which comprises at least one silver halide emulsion layer, the improvement according to which the development is carried out in the presence of a compound of the following formula: in which R represents an alkyl group having up to six carbon atoms; two R radicals attached to the same nitrogen atom may with the said nitrogen atom form a saturated five-, six- or seven-membered heterocyclic ring containing at least one hetero atom or an unsaturated heterocyclic ring, in the latter case R'' is not present; R'' represents an alkyl group having up to six carbon atoms, which may be substituted or an aralkyl group, the aryl radicals of which may be substituted; R'''' represents H or -CO-CH3; n is an integer of from 1 to 6; X is any anion; when R'' contains a carboxylate group, X is absent.
10. The process according to claim 9, wherein the exposed photographic material is developed with a color-forming developer in the presence of color couplers.
11. In the process for the preparation of photographic silver halide emulsions by precipitating the silver halide in the presence of a protective colloid, washing and chemical ripening the improvement according to which the chemical ripening is carried out in the presence of a compound of the following formula: in which R represents an alkyl group having up to six carbon atoms; two R radicals attached to the same nitrogen atom may with the said nitrogen atom form a saturated five-, six- or seven-membered heterocyclic ring containing at least one hetero atom or an unsaturated heterocyclic ring, in the latter case R'' is not present; R'' represents an alkyl group having up to six carbon atoms, which may be substituted or an aralkyl group, the aryl radicals of which may be substituted; R'''' represents H or -CO-CH3; n is an integer of from 1 to 6; X is any anion; when R'' contains a carboxylate group, X is absent.