GB2023862A - A photographic material containing latent image stabilisers. - Google Patents

Abstract

A process is disclosed for the production of a silver halide emulsion containing as a latent image stabiliser a hydroxy indane corresponding to the formula: <IMAGE> wherein R<1>, R<2>, R<3>, R<4>, R<5> and R<6> represent hydrogen. C1-4-alkyl; or aryl; R<7> represents hydrogen; C1-4-alkyl; halogen; carboxyl; or another hydroxyl indane radical attached through -SO2-, -O- or through a straight-chain or branched alkylene bridge. The process comprises adding to the emulsion the hydroxy indane of formula I which is dissolved in such a way that it is not emulsified in the emulsion, e.g. they are added in solution in solvents such as water, aqueous alkalis, alcohols, tertrahydrofuran, acetone, and/or dimethyl formamide.

Description

SPECIFICATION A photographic material containing latent image stabilisers.

This invention relates to a photographic material containing at least one silver halide emulsion layer and latent image stabilisers, to its production and to its use for the production of photographic images.

It is known that the latent image nuclei of exposed silver halide emulsions are not stable in storage. This phenomenon is described, for example, in "The Theory of the Photographic Process", 4th Edition, Macmillan Publishing Co., New York, 1977, pages 167 etseq.

Degeneration of the latent timage (fading) is generally reflected in the fact that an exposed material which was stored before development is less sensitive than a material which was not stored after exposure.

Although the reasons for degeneration of the latent image have not yet been fully explained, it is assumed that it is initiated by substances in the emulsion, for example impurities or additives, which oxidise some of the silver of which the latent image consists. Degeneration of the latent image is extremely troublesome in practice not only for recording materials, which are normally stored in exposed form for a prolonged period before development, but also for copying materials in cases where they are not developed immediately after exposure. Roll-form copying materials in particular are often developed some days after exposure.

It is known that so-called latent image stabilisers can be added to photographic silver halide emulsions to stabilise the latent image nuclei. Latent image stabilisers are described, for example, in German Offenlegungsschrift Nos. 2,217,153; 1,107,508 and 2,325,039; in German Auslegeschrift Nos. 1,199,612 and 1,173,339 and in British Patent Nos. 1,412,294, 1,378,354; 1,386,630; 1,453,388 and 1,458,107.

One disadvantage common to the compounds described in these specifications, however, is that the latent image nuclei are stabilized to a minimal extent only, if at all, in addition to which hardening of the gelatin by conventional hardners is impaired.

Accordingly, one object of the present invention is to obtain improved latent image stabilisation.

It has now been found that latent image nuclei can be stabilised, even in storage under extreme conditions, such as the humid conditions prevailing in tropical climates, by adding to the photographic silver halide emulsions hydroxy indanes corresponding to the following general formula:

wherein R1, R2, Rs, R4, R5 and R6 represent hydrogen; a C1#4-alkyl; or aryl; R7 represents hydrogen; C1 4-alkyl; halogen; carboxyl; or another hydroxy indane radical attached through -S02-, -0-or through s straight-chain or branched alkylene bridge and corresponding to the following general formula:

wherein R1 to R6 are defined as above, andlor R5 and R6 together represent the radical required to complete a carbocyclic ring.

Furthermore, a process for making a photographic material is provided which comprises coating a support with at least one silver halide emulsion containing at least one compound according to formula I.

Furthermore, a photographic material is provided which comprises a support bearing at least one silver halide emulsion layer and optionally further layers, the material containing at least one compound according to formula Preferred aryl groups are phenyl and hydroxy-phenyl.

The above-mentioned alkyl, cycloalkyl and aryl radicals may optionally contain one or more further substituents such as alkly, aryl, halogen cyano, hydroxy, mercapto, amino, carboxy, sulpho, sulphamoyl or pyridyl, which may themselves be substituted one or more times.

Particularly suitable compounds correspond to the following general formula:

wherein the substituents R2, R3, R5, r6 and R7 are defined as in forumal (I).

The compounds corresponding to formula (II) listed in Table (1) below have proved to be particularly suitable: Table 1

Compound R2 R3 R5 R6 R7 No.

1 1 CH3 H CH3 CH3 H 2 CH3 H CH3 CH3 COOH 3 CH3 H C6H5 CH3 H 4 CH3 CH3 CH3 CH3 H 5 CH3 H CH3 CH3 tert.-C4H9 6 6 H H CH3 CH3 H OH H CHHi CH## H 8 CH3 H CH3 CH3 C1 9 CH3 H CH3 C2H5 H 10 CH3 H - [ CH2 ] 5- H OH 11 CH3 H CH3 CH3 -CH2 CH3 H3C - CH3 CH3 CHJ 12 CH3 H - [ CH215- tert.-C4Hs' The hydroxy indanes used in accordance with the present invention are known for example from German Offenlegungsschrift No. 2,319,079 and may be obtained as described therein by reacting alkyl phenols with olefins. Reference is also made to German Offenlegungsschrift Nos. 2,304,588 and 2,526,468.

The hydroxy indanes used in accordance with the present invention are eminently suitable for increasing the stability of the latent image nuclei in photosensitive photographic materials containing at least one silver halide emulsion layer. The stability of the latent image nuclei is obtained without any effect on the other usual photographic properties which are, of course, largely determined by the structure of the silver halide emulsion, even when the materials are stored for prolonged periods at normal temperature or at elevated temperature in a heating cabinet or even under tropical conditions, i.e. under high atmospheric humidity.

The hydroxy indanes used in accordance with the present invention may be added to the photographic material at any stage of its production after physical ripening of the silver halide emulsion. The derivatives are preferably added in dissolved form to the photosensitive silver halide emulsion during or after chemical ripening or to the actual casting solution. Suitable solvents are, in particular, water, aqueous alkalis, lower aliphatic alcohols, tetrahydrofuran, acetone, dimethyl formamide or mixtures thereof. The concentration of the hydroxy indane derivatives in the photographic materials may vary within wide limits. It is determined by the required effect, by the type of reproduction process used and by the structure of the photographic material.

Where the hydroxy indanes are used in a silver halide emulsion layer, quantities of from 10 mg to 5000 mg per mole of silver halide have proved to be particularly suitable. Concentrations of from 50 mg to 1000 mg per mole of silver halide are particularly preferred. The hydroxy indanes used in accordance with the present invention may be used for stabilising the latent image nuclei in standard photosensitive materials which are suitable for the production of black -and-white images, for example black-and-white recording or copying materials or reversal materials. In addition, the material may contain colour couplers without this having any adverse effect upon stabilisation.

Conventional silver halide emulsions are suitable for the purposes of the present invention. They may contain as the silver halide silver chloride, silver bromide, silver iodide and mixtures thereof.

Suitable protective colloids and binders for the silver halide emulsion layer are the conventional hydrophilic film-forming materials, for example proteins, particularly gelatin, alginic acid or derivatives thereof, such as esters, amides or salts, cellulose derivatives, such as carboxy methyl cellulose and cellulose sulphate, starch or derivatives thereof or hydrophilic synthetic binders, such as polyvinyl alcohol, partially hydrolysed polyvinyl acetate, and polyvinyl pyrrolidone. The layers may also contain a admixture with the hydrophilic binders other synthetic binders in dissolved or dispersed form, such as homopolymers or copolymers or acrylic or methacrylic acid their derivatives, such as esters, amides or nitriles, also vinyl polymers, such vinyl esters or vinyl ethers.

The emulsions according to the present invention may be applied to conventional layer supports, for example supports of cellulose esters, such as cellulose acetate or cellulose acetobutyrate, also polyesters, particularly polyethylene terephthalate, or polycarbonates, particularly based on bis-phenylol propane.

Other suitable supports are paper supports which may optionally contain water-impermeable polyolefin layers, for example of polyethylene or polypropylene, also supports of glass or metal.

The emulsions may also be chemically sensitised, for example by the addition during chemical ripening of sulphur-containing compounds, for example allyl isothio-cyanate, allyl thiourea and sodium thiosulphate.

Other suitable chemical sensitisers are reducing agents, for example, the tin compounds described in Belgian Patent Nos. 493,464 or 568,687, also polyamines, such as diathylene triamine or aminomethyl sulphinic acid derivatives, for example according to Belgian Patent No. 547,323.

Other suitable chemical sensitisers are noble metals and noble metal compounds, such as gold, platinum, palladium, iridium, ruthenium or rhodium. This method of chemical sensitisation is described in the article by R. Koslowsky in Z.Wiss.Phot, 46, pages 65-72 (1951).

It is also possible to sensitise the emulsions with polyalkylene oxide derivatives, for example with polyethylene oxide having a molecular weight of from 1000 to 20,000, with condensation products of alkylene oxides and aliphatic alcohols, glycols, cyclic dehydration products of hexitols, with alkyl-substituted phenols, aliphatic carboxylic acids, aliphatic amines, aliphatic diamines and amides. The condensation products have a molecular weight of at least 700 and preferably of more than 1000. To obtain particular effects, these sensitisers may of course be used in combination with one another, as described in Belgian Patent No. 537,278 and in British Patent No. 727,982.

The emulsions may also be optically sensitised, for example, using conventional polymethine dyes, such as neutrocyanines, basic or acid carbocyanines, rhodacyanines, hemicyanines, styryl dyes and oxonols.

Sensitisers such as these are described in F.M. Hamer's work entitled "The Cyanine Dyes and Related Compounds", 1964, Interscience Publishers, John Wiley and Sons.

The emulsions may contain conventional stabilisers such as homopolar or salt-like compounds of mercury with aromatic or heterocyclic rings, such as mercapto triazoles, simple mercury salts, sulphonium-mercury double salts and other mercury compounds. Other suitable stabilisers are azaindences, preferably tetra- or penta-azaindenes, particularly those substituted by hydroxyl or amino groups. Compounds such as these are described in the article by Birr in Z.Wiss. Phot. 47 (1952), pages 2-58. Other suitable stabilisers are inter alia heterocyclic mercapto compounds, for example phenyl mercapto tetrazole, quaternary benzthiazole derivatives and benzotriazole.

The emulsions may be hardened in the conventional way, for example using formaldehyde or halogen-substituted aldehydes containing carboxyl group, such as mucobromic acid, diketones, methane sulphonic acid esters and dialdehydes.

The photographic layers may also be hardened using hardeners of the epoxy, hetrocyclic ethylene imine or acryloyl type. Examples of hardeners such as these are described, for example, in German Offenlegungsschrift No. 2,263,602 or in British Patent No. 1,266,655. It is also possible to harden the layers by the process described in German Offenlegungsschrift No.2,218,009 in order to obtain colour photographic materials which are suitable for processing at high temperatures.

It is also possible to harden the photographic layers or the colour photographic multilayer materials using hardeners of the diazine, triaxine or 1,2-dihydroquinolineseries, as described in British Patent Nos.

1,193,290; 1,251,091; 1,306,544 and 1,266,655; in French Patent No. 71 02 716 or in German Offenlegungsschrift No. 2,332,317. Examples of hardeners such as these are diazine derivatives containing alkyl or aryl sulphonyl groups, derivatives of hydrogenated diazines ortriazines, such as 1,3,5-hexahydrotriazine, flourine-substituted diazine derivatives such as flouropyrimidine, esters of 2-substituted 1,2 dihtdroquinoline or 1,2-dihydroisoquinoline-N-carboxylic acids. Other suitable hardeners are vinyl sulphonic acid hardeners, carbodiimide or carbamoyl hardeners, as described, for example, in German Offenlegungsschrift Nos. 2,263,602; 2,225,230 and 1,808,685, in French Patent No. 1,491,807, in German Patent No.

872,153 and in East German Patent No. 7218. Other suitable hardeners are described, for example, in British Patent No. 1,268,550.

The present invention may be used both for the production of black-and-white photographic images and also for the production of coloured photographic images. Coloured photographic images may be obtained, for example, by the known principle of chromogenic development in the presence of colour couplers which react with the oxidation products of dye-giving p-phenylene diamine developers to form dyes.

The colour couplers may be added, for example, to the colour developer on the principle of the developing-in process. In one preferred embodiment, the photographic material itself contains the conventional colour couplers which are generally incorporated-into the silver halide layers. Thus, the red-sensitive layer may contain, for example, a non-diffusing colour coupler for producing the cyan component colour image, generally a coupler of the phenol or a-naphthol type. The green-sensitive layer may contain, for example, at least one non-diffusing colour coupler for producing the magenta component colour image, colour couplers of the 5-pyrazolone or imidazolone type normally being used. The blue sensitive layer may contain, for example, a non-diffusing colour coupler for producing the yellow component colour image, generally a colour coupler containing an open-chain ketomethylene group.Many colour couplers of this type are known and are described in a large number of patent specifications. In this connection, reference is made, for example, to the article entitled "Farbkuppler (Colour Couplers)" by W.Pelz in "mitteilungen aus den Forschungslaboratorien derAgfa, Leverkusen/Munchen",VoI. lit (1961) and to K.

Ventkataraman in "The Chemistry of Synthetic Dyes", Vol. 4, pages 341-387, Academic Press, 1971.

Other suitable non-diffusing colour couplers are 2-equivalent couplers. 2-Equivalent couplers contain a removable substituent in the coupling position, so that in contrast to the usual 4-equivalent couplers they only require 2 equivalents of silver halide for dye formation. Suitable 2-equivalent couplers include, for example, the known DIR-couplers, in which the removable radical is liberated as a diffusing development inhibitor after reaction with colour developer oxidation products. In addition, the so-called white couplers may be used for improving the propertiers of the photographic material.

The non-diffusing colour couplers and dye-giving compounds may be added to the photosensitive silver halide emulsions or other casting solutions by using known methods. In the case of water-soluble or alkali-soluble compounds, they may be added to the emulsions in the form of aqueous solutions, optionally with the addition of water-miscible organic solvents, such as ethanol, acetone or dimethyl formamide.

Where the non-diffusing colour couplers and dye-giving compounds are water-insoluble or alkali-insoluble compounds, they may be emulsified by a known method, for example, by directly mixing a solution of these compounds in a low-boiling organic solvent with the silver halide emulsion or initially with an aqueous gelatin solution, after which the organic solvent is removed in the conventional way. The resulting gelatin emulsion of the particular compound is then mixed with the silver halide emulsion. So-called coupler solvents or oil formers may additionally be used for emulsifying hydrophobic compounds of the type in question.Coupler solvents or oil formers are generally relatively high boiling organic compounds which include the non-diffusing colour couplers and development-inhibitor-releasing compounds to be emulsified in the silver halide emulsion in the form of oily droplets. In this connection, reference is made, for example, to US Patent Nos. 2,322,027; 2,533,514; 3,689,271; 3.764,336 and 3,765,897.

Photographic material according to the invention may be developed with the usual colour developer substances, for example N,N-dimethyl-p-phenylene diamine, 4-amino-3-methyl-N-ethyl-N-methoxyethyl aniline, 2-amino-5-diethylamino toluene, N-butyl-N-ol-sulphobutyl-p-phenylene diamine; 2-amino-5-(n-ethyl-N-ss-methane sulphaemidoethyl-amino)-toluene.

N-ethyl-N-ss-hydroxyethyl-p-phenylene diamine, N,N-bis-(#-hydrnxyethyl)-p-phenylene diamine, 2-amino-5-( N-ethyl-N-ss-hydroxyethylamino)-toluene.

Other suitable colour developers are described for example in J. Amer. Chem. Soc. 73, 3100 (1951).

One particular advantage of the hydroxy indanes used in accordance with the present invention is that stabilisation of the latent image nuclei does not necessitate the simultaneous use of certain hardeners for the gelatin. The present invention is illustrated by the following Examples: Example 1 A high sensitive silver bromide iodide emulsion conaining 6 mole % of silver iodide is prepared, flocculated and freed from the soluble salts in the conventional way. After redispersion, gelatin is added to the emulsion which is then ripened by a known method with sulphur and gold compounds. The emulsion had a silver nitrate/gelatin ratio of 1:1 and contained 95g of silver per kg of emulsion the silver being expressed as silver nitrate.

Before casting, the above-mentioned emulsion is divided into 5 equal portions, and the following ingredients are added to these portions: 200 mg/kg of emulsion of 4-hydrnxy-6- methyl-l ,3,3a,7-te-traazaindene in the form of a 1% alkaline aqueous solution; 600 mg/kg of emulsion of saponin in the form of a 10% solution in water; 10 ml/kg of emulsion of a 10% aqueous formaldehyde solution; 10 ml/kg of emulsion of a 20% aqueous potassium bromide solution; and a stabiliser in the form of a 1% alcohol solution in the quantities per kg of emulsion indicated in Table (2) below.

The emulsions were then cast onto a cellulose acetate support in such a way that the silver coating, expressed as silver nitrate, amounted to 5.5 g per square metre. The samples were dried in a conventional way, exposed behind a grey step wedge in a sensitometer and, after the treatments indicated in Table 2, were developed for 7 and 16 minutes at 200C in a developer of the following composition: sodium sulphite sicc. 70 g borax 7.0g hydroquinone 3.5g p-monomethyl aminophenol sulphate 3.59 sodium citrate 7.09 potassium bromide 0.4g made up with water to 1 litre.

The results of the sensitometric evaluation are as shown in Table 2.

Table 2 Sensitivity after storage Compound Quantity (fresh) 3 days 7 days 30 days No. added at 60 C at 35 C/ at room (mg) 85% r.H. tempera ture Control test- standard -4.5 -5.5 -8 2 60 standard -1.0 -1.2 -1.5 11 60 standard -1.8 -1.7 -2.0 1 1 60 standard -1.2 -1.3 -1.1 3 60 standard -1.8 -1.8 -1.5 Pyrocatechol 100 standard -3.0 -3.5 -4.5 In Table 2, the sensitivity is evaluated in relation to the test taken as a control. Accordingly differences in sensitivity are quoted. An increase in this value of 3 units means that sensitivity is doubled. Sensitivity itself is determined at a density of 0.2 over fog.

The compound pyrocatechol known from German Auslegeschrift No. 1,107,508 is used as the comparison substance. The material finished with it was produced in the same way as the material according to the present invention, except that 100 mg of this compound were added instead of a compound according to the present invention.

Example 2 An ultra-sensitive blue-sensitive silver bromide iodide emulsion having an iodide content of 6 mole %, a silver-gelatin ratio of 1:0.6 and a silver content of 135 g per kg of emulsion is prepared, the silver being expressed as silver nitrate in each case. The pH value is adjusted to 6.5 and the pAg value to 8.4. Before casting, the following ingredients are added to the emulsion: 1. 100mg/kg of emulsion of 4-hydroxy-6-methy-1 ,3,3a,7-tetraazaindene (1 % alkaline aqueous solution): 2. 540 ml/kg of emulsion of a 5% alkaline solution of a yellow coupler corresponding to the following formula:

3.The quantities per kg of emulsion indicated in Table )3) of a latent image stabiliser; 4. 300 mg/kg of emulsion of an instant hardener corresponding to the following formula dissolved in 30 ml of water

The emulsion obtained is cast onto a cellulose acetate support (in such a way that the silver coating, expressed as silver nitrate, amounted to 2.2 g per square metre).

The material obtained is exposed imagewise in the conventional way and, as indicated in Table 3, is developed using the following developers for 3.25 minutes at 380C immediately, and after storage for 4 weeks at room temperature.

Developers 1-hydroxyethane-l, 1-disphosphonic acid 29 ethylene diamine-N,N,N',N'-tetraacetic acid 29 potassium carbonate sicc. 34.1 g sodium hydrogen carbonate sicc. 1.55g sodium disulphite sicc. 0.28g sodium sulphite sicc. 3.46g potassium bromide 1.34g hydroxylamine sulphate 2.4 g 4-amino-3-methyl-N-ethyl-N-(ss-hydroxy- ethyl)-aniline 4.7 g made up with water to 1 litre Further processing comprises treatment in the following baths in the order shown: stop bath 1 minute at 38 C; bleach bath 3.25 minutes at 38 C; rinsing with water 3.5 minutes at 38 C; fixing bath 3.25 minutes at 38 C; rinsing with water 5 minutes at 38 C.

The stop, bleach and fixing baths used corresond to those normally used (British Journal of Photography, 1974, pages 597 and 598).

The results obtained are shown in Table (3).

Table 3 Sensitivity Compound Quantity Exposure and Development of No. added development of the material 30 (mg) the fresh material days after exposure; storage at room temperature control - standard -1.5 control standard -1.4 1 100 standard -1.0 200 standard -0.7 400 standard -0.2 2 100 standard -0.8 200 standard -0.5 400 standard +0.2 The materials indicated in Table 3 are sensitometrically evaluated in the same way as in Example 1.

Claims (7)

1. A process for the production of a silver halide emulsion containing at least one hydroxy indane as a latent image stabiliser, said hydroxy indane corresponding to the following general formula:

wherein R1, R2, R3, R4, R5 and R6 represent hydrogen; C1.4-alkyl or aryl; R7 represents hydrogen; Cm 4, halogen, carboxyl; or another hydroxy indane radical attached through -SO2-, -0-or through a straight-chain or branched alkylene bridge and corresponding to the following general formula:

wherein R1 to R6 are defined as above, and/or R5 and R6 together the radical required to complete a carbocyclic ring; said process comprising adding to the emulsion the said hydroxy indane which is dissolved in such a way that it is not emulsified in the emulsion.

2. A process as claimed in Claim 1, wherein R1 represents methyl and R4 represents hydrogen.

3. A process for the production of a silver halide emulsion as claimed in Claim 1, substantially as described with particular reference to the Examples.

4. A silver halide emulsion when produced by a process as claimed in any of claims 1 to 3.

5. A process for producing a photographic material comprising a support bearing one or more layers, which comprises incorporating at least one layer of silver halide emulsion as claimed in Claim 4.

6. A photosensitive photographic material comprising a support bearing at least one silver halide emulsion compound which corresponds to the following general formula and which is present in a non-emulsified form:

wherein R1, R2, R3, R4, R5 and R6 represent hydrogen; C1.4-alkyl; or aryl; R7 represents hydrogen; C1#alkyl; halogen; carboxyl; or another hydroxy indane radical attached through -SO2-, -0- or through a straight-chain or branched alkylene bridge and corresponding to the following general forumla:

wherein R1 to R6 are defined as above; and/or R5 and R6 together represent the radical required to complete a carbocyclic ring.

7. A proces for producing a photogtaphic image which comprises the imagewise exposure and development of a photographic material as claimed in Claim 6.