GB2034495A

GB2034495A - Light sensitive silver halide reproduction material

Info

Publication number: GB2034495A
Application number: GB7935183A
Authority: GB
Original assignee: EI Du Pont de Nemours and Co
Current assignee: EIDP Inc
Priority date: 1978-10-11
Filing date: 1979-10-10
Publication date: 1980-06-04
Also published as: GB2034495B; JPS5553327A; FR2438860B1; DE2844231A1; DE2844231C2; JPS5831572B2; FR2438860A1; BE879306A

Abstract

A light-sensitive silver halide reproduction material of high gradation stability which comprises a support film, at least one silver halide emulsion layer, and optionally nonlight-sensitive auxiliary layers, and contains a disulfide compound substituted by two heterocyclic radicals, and a thiazolidine compound. Precursors of the thiazolidine compound, e.g. cystein or penicillamine, can be used. The disulphide compound is of the formula <IMAGE> and the thiazolidine of the formula <IMAGE> wherein X represents the atoms necessary to complete a heterocyclic ring and R, R1, R2, R3 and R4 represent hydrogen, alkyl of 1 to 4 carbon atoms or aryl. <IMAGE>

Description

SPECIFICATION Light sensitive silver halide reproduction material The invention relates to a light-sensitive silverhalide reproduction material of high gradation stability and - more particularly, one which contains a disulfide compound substituted by two heterocyclic radicals and a thiazolidine compound, Silver halide reproduction materials which contain disulfide compounds substituted by two heterocyclic radicals are known to prevent fogging of silver halide emulsions and/or to improve the fog-lowering effect of sulfinic or seleninic acids.

Silver halide materials which contain thiazolidine carboxylic acids are likewise known to improve the sensitivity-fogging ratio. Moreover, it is stated in P. Glafkides, Chimie et Physique Photographiques, 3d edition, Paris, 1967, p. 313, that thiazolidine carboxylic acids act as contrast-modifying desensitizers whereby negative emulsions are desensitized, while with positive emulsions gradation is elevated at the cost of sensitivity.

It is, moreover, known that in the development of a light-sensitive silver halide reproduction material the silver formed, and thus also gradation, which largely determines the image character, depends to a great extent on development conditions, especially on time and temperature of development. Therefore, it is endeavored to keep the time and temperature of development as constant as possible. In actual practice, however, this has not been possible to a satisfactory degree.

Gradation stability is of special significance in the development of x-ray films where for diagnostic reasons a high constancy of gradation is required. Today, as a result of the short development times used, these are very susceptible to deviations of development conditions, especially against over development. Thus, the task of the present invention is to provide a light-sensitive silver halide reproduction material which excels in high gradation stability during development under various conditions.

This task was solved by a light-sensitive silver halide reproduction material, which, if desired, is hardened and which consists of a support film, at least one light-sensitive silver halide emulsion layer, and, if desired, additional nonlight-sensitive auxiliary layers, characterized in that the reproduction material contains a) a disulfide compound of the formula

and b) a thiazolidine compound of the formula

wherein X represents the atoms necessary to complete, if desired, a substituted heterocyclic ring, and R, R1, RZ, RJ, and R4 are the same or different and represent hydrogen, alkyl radicals with 1-4 carbon atoms, and aryl radicals.

Suitable heterocyclic rings for the disulfide compound are oxazol, thiazol, imidazol, pyrimidine, oxadiazol, thiadizol, triazol, tetrazol, etc.

For additional examples of suitable heterocycles, see E. J. Birr, Stabilization of Photographic Silver Halide Emulsions, "The Focal Press", London and New York, 1974. The heterocyclic rings can also be substituted or can be parts of polynuclear ring systems. Examples of this, for example, are 2-aminothiadiazol, 1-phenyl-tetrazol, benzthiazol, etc. Disulfide compounds are added to the photographic silver halide emulsion in amounts of 10-30 mg/mole silver halide as ca. 0.5% solutions in aqueous or water-miscible organic solvents. Addition can be at any point in time, preferably after chemical ripening. It is also possible to add the disulfide compounds to a water-permeable auxiliary layer in direct contact with the photographic emulsion layer.

An especially suitable disulfide compound is bis-(5-mercapto-1 ,3,4-thiadiazol-2 yl-) disulfide, which, in addition to its good gradation stabilizing effect, further excels by providing especially good stability for the remaining sensitometric data. Anhydrous organic solvents have proven to be best as solvents for this disulfide, as for example, methanol, an hydrous ethanol, or dimethyl formamide.

The thiazolidine compounds, or, if desired, their salts, are added to the photographic silver halide emulsion in amounts of 5-20 mg/mole silver halide as ca. 0.5% aqueous solutions at a random point in time, preferably after chemical ripening. It is also possible to add the thiazolidine compounds to a water permeable auxiliary layer in direct contact with the photographic emulsion.

In a special form of embodiment, suitable thiazolidine precursor compounds can also be added in place of the thiazolidine compounds. In this case, the photographic silver halide emulsion must be hardened by an aldehyde hardening agent, for example, by formaldehyde or glyoxal or glutardialdehyde, etc. which reacts with the precursor compound to form a thiazolidine compound. For example, cystein or penicillamine, etc.

are suitable precursor compounds for this purpose. In addition to the disulfide compounds of the invention and the thiazolidine compounds, the photographic emulsions can contain conventional chemical and, if desired, optical sensitizers as well as conventional stabilizers and antifogging agents. Moreover, the emulsion may also contain additives elevating the covering power; also wetting agents, antistatic agents, hardeners, etc.

Example 1 A highly sensitive silver bromoiodide emulsion with about 2 mole % Agl was prepared which contained 5 wt. % gelatin and 10 wt. % silver halide. This emulsion was divided into 4 parts. Part A contained no additives of the invention, while to Parts B, C and D were added the ingredients indicated in the table, shortly before coating.

Disulfide Compound Thiazolidine Compound per mole silver per mole silver Sample halide halide A B - 17 mg thiazolidine-4-car boxylic acid C 17 mg Bis-(1 -phenyl tetrazolyl-5-) disulfide D 17 mg 17 mg Bis-(1-phenyl- thiazolidine-4 tetrazolyl-5-) carboxylic acid disulfide The emulsions were coated according to known processes onto a polyethylene glycol terephthalate film support and were dried. These light-sensitive materials were exposed, developed, and subjected to a normal sensitometric evaluation, wherein a developer of the following composition was used: Hydroquinone 30.00 g 1-Phenyl-3-pyrazolidone 1.wog Na2SO3 (anhydrous) 60.00 g KOH 23.wog NaBO2,4H2O 20.00 g Water to 1 liter 15, 22 and 51 s were selected as times of development.The results are summarized in the following table.

Normal Sample Underdevelopment Development Overdevelopment 34 C/15 s 34 C/22 s 34 C/51 s % % Sensi- Grada- Sensi- Grada- Sensi- Grada tivity tion Fog tivity tion Fog tivity tion Fog A 74 3.5 0.16 100 3.3 0.20 170 2.5 0.31 B 98 3.4 0.23 129 3.3 0.24 195 2.6 0.34 C 66 3.4 0.16 77 3.5 0.17 126 2.9 0.19 D 98 3.3 0.20 129 3.3 0.20 190 3.2 0.31 Evaluation points out thes gradation-stabilizing effect of Sample D of the invention against comparative Sample A and Samples B and C containing the individual components.

Example 2 The silver emulsion described in Example 1 was prepared and divided into 3 parts. To the individual parts, shortly before coating, were added the disulfide- and thiazolidine compounds indicated in the following table.

Disulfide Compound Thiazolidine Compound per mole silver per mole silver Sample halide halide A B 13 mg 11mg Bis-(5-acetyl- 2-methyl-thiazolidine mercapto-1,3,4- 4-carboxylic acid thiadiazolyl-2-) disulfide C 13 mg 11 mg Bis-(5-mercapto-) Thiazolidine-4 thiadiazolyl-2. carboxylic acid disulfide The emulsions were coated, dried, exposed and developed as indicated. Evaluation indicated the following values: Gradation Gradation Gradation with under- with normal with over development development development Sample 34 C/15s 34 C/22s 34 C/51 s A 3.4 3.2 2.3 B 3.4 3.4 2.9 C C 3.4 3.2 3.1 The gradation-stabilizing effect of the additives of the invention with longer development times is clearly illustrated.

Example 3 A silver halide emulsion as described in Example 1 was prepared and divided into 4 parts. To the individual parts, shorting before casting, were added the disulfide- and thiazolidine compounds indicated in the following table.

Disulfide Compound Thiazolidine Compound per mole silver per mole silver Sample halide halide A B 27mg 7 mg Bis-(1-phenyl- 2,2'-dimethyl tetrazolyl-5-) thiazolidine-4 disulfide carboxylic acid C C 11 mg 10 mg Bis-(benz- Thiazolidine-4 thiazolyl-2-) carboxylic acid disulfide ethyl ester D 11 mg 10 mg Bis-(5-amino- Thiazolidine-4 thiadiazolyl-2-) carboxylic acid disulfide ethyl ester.

The emulsions were coated and dried as indicated. After exposure, development took place at 30, 34 and 38 C. Evaluation yielded the following values: Gradation Gradation Gradation with under- with normal with over development development development Sample 30 C/22 s 34C/22 s 38 C/22 s A 3.2 3.2 2.1 B 3.3 3.3 2.8 C 3.2 3.1 2.7 D 3.4 3.3 2.9 As seen from the above table, the same gradation-stabilizing effect is also evident upon variation of the temperature of development.

Example 4 The effect of the invention is also seen when using thiazolidine precursor compound in combination with a disulfide compound.

A silver halide emulsion as described in Example 1 was prepared and hardened using formaldehyde. The emulsion was divided into 3 parts to which were added a disulfide compound and, in place of the thiazolidine compound, a precursor compound from the following table: Disulfide Compound Thiazolidine Precursor per mole silver Compound per mote Sample halide silver halide A B - 7 mg Cystein C 13 mg 7 mg Bis(-1-phenyl- Cystein tetrazolyl-5-) disulfide The emulsions were coated, dried, exposed and developed as indicated. Evaluation yielded the following values: Gradation Gradation Gradation with under- with normal with over development development development Sample 34 C/15s 34 C/22s 34 C/51 s A 3.3 3.2 2.6 B 3.2 2.9 2.4 C 3.0 3.0 3.0

Claims

1. A light-sensitive, optionally hardened, silver halide reproduction rnaterial which consists essentially of a support film, at least one light-sensitive silver halide emulsion layer, and, if desired, additional nonlight-sensitive auxiliary layers, the material containing.

a) a disulfide compound oftheformula

and b) a thiazolidine compound of the formula

wherein X represents the atoms necessary to complete a substituted heterocyclic ring, and R, R1, R2, R3, and Re which may be the same or different, each represent hydrogen, alkyl of 1 to 4 carbon atoms or aryl.

2. A reproduction material according to claim 1, wherein the disulfide compound a) is bis-(5-mercapto-1, 3,4-thiadiazolyl-2-) disulfide, and the thiazolidine compound b) is thiazolidine-4-carboxylic acid.

3. A reproduction material according to claim 1 or 2, which has been hardened by an aldehyde hardener and contains the thiazolidine compound b) in the form of a precursor compound.

4. A reproduction material according to claim 3, wherein cystein is the precursor compound.

5. A reproduction material according to claim 1 substantially as described in any one of the Examples.