US3754918A

US3754918A - Dye bleaching bath for the silver dye bleaching process

Info

Publication number: US3754918A
Application number: US00166906A
Authority: US
Inventors: S Hunig; M Heilmann; P Bergthaller
Original assignee: Agfa Gevaert AG
Current assignee: Agfa Gevaert AG
Priority date: 1970-07-31
Filing date: 1971-07-28
Publication date: 1973-08-28
Anticipated expiration: 1990-08-28
Also published as: DE2038008A1; FR2099403A5; BE769599A; CH569991A5; GB1341575A

Abstract

Color photographic images are produced by the silver dye bleaching process in which the bleaching is accelerated with a bleaching bath containing substituted 1,5-diazanaphthalenes as defined below.

Description

United States Patent 1191 Hiinig et al.

[ DYE BLEACHING BATH FOR THE SILVER DYE BLEACHING PROCESS [75] inventors: Siegfried Hiinig, Wurzburg; Max

Heilmann, Cologne; Peter Bergthaller, Leichlingen, all of Germany 73 1' Assignee: Agfa-Gevaert Aktiengesellschaft,

Leverkusen, Germany 22 Filed: July 28,1971

211 App]. No.: 166,906

[30] Foreign Application Priority Data July 31, 1970 Germany P 20 38 008.9

[52] US. Cl 96/53, 96/20 [51] Int. Cl G03c 7/00 [451 Aug. 28, 1973 [58] Field of Search 96/53, 73, 20

[56] References Cited UNIT ED STATES PATENTS 3,480,438 11/1969 Freytag et al 96/53 3,656,953 4/1972 Schlunke et a1. 96/53 Primary Examiner-Norman G. Torchin Assistant Examiner-R. L. Schilling Attorney-Arthur C. Connolly, Albert F. Bower et a1.

[57] ABSTRACT Color photographic images are produced by the silver dye bleaching process in which the bleaching is accelerated with a bleaching bath containing substituted 1 ,5- diazanaphthalenes as defined below.

7 Claims, 1 Drawing Figure DYE BLEACHING BATH FOR THE SILVER DYE BLEACHING PROCESS The present invention relates to a dye bleaching bath for the silver dye bleaching process, which bath contains derivatives of 1,5-diazanapthalene as bleaching catalysts.

In the known silver dye bleaching process, a photographic material comprising light-sensitive silver halide emulsion layers which contain azo dyes is exposed to light and then developed and fixed in the usual manner. A negative silver image of the original is obtained in the emulsion layers. The photographic material is then treated with a dye bleaching bath and, as the last stage of processing, with a silver bleaching bath or bleach fixing bath. A positive color image of the original is obtained. The process is based on the bleaching of organic dyes, especially azo dyes, with finely divided silver, in this case the photographically produced image silver, the extent of bleaching depending on the quantity of silver present.

Successful bleaching of the dye in the course of the photographic process is essential for the economy of the process and the quality of the color images obtained. A particularly important factor is that bleaching should be sufficiently rapid.

The known baths, which contain as their main components an inorganic or organic acid and substances which form silver salts or silver complexes, generally bleach too slowly, so that it is necessary to use bleaching catalysts at the same time. Heterocyclic nitrogen compounds are suitable for this purpose, e.g., quinoline, isoquinoline or derivatives thereof, quinoxalines and azines such as phenazine or naphthazine. In spite of the use of bleaching catalysts, it is desirable to shorten the bleaching time even further.

It is among the objects of the present invention to provide bleaching baths for the silver dye bleaching process which enable sufficiently rapid bleaching to be achieved, the rate depending on the quantity of silver present.

We now have found a bleaching bath for the silver dye bleaching process, which bath contains inorganic or organic acids, a substance which forms silver salts or silver complex salts, and a heterocyclic nitrogen compound as bleaching catalyst, said compound being a derivative of 1,5-diazanaphthalene of the following formula:

n is 0,1 or 2.

The bleaching catalysts to be used according to the invention are very highly active even in relatively small concentrations. They are, therefore, considerably superior for this purpose to the known unsubstituted l,5- diazanaphthalene.

The following are examples of suitable compounds:

1. 1,5-dimethyl-1,S-diazanaphthalenium-bismethylsulfate 2. 1,5-diethyl-1 ,5-diazanapthalenium-bis-ethylsulfate 3. 1 ,S-bis-m-sulfopropyl-l ,S-diazanaphthalenium betaine 4. 1,5-di-n-butyl-1,S-diazanaphthalenium-bis-butyl sulfate 5 l-m-sulfopropyl betaine-5-methyl-1,5-

diazanaphthalenium methylsulfate.

The compounds which are to be used according to the invention are prepared by known methods. The simplest method is to start from unsubstituted 1,5- diazanaphthalene and react this with a powerful alkylating agent, e.g., with dimethyl sulfate, diethyl sulfate or alkyloxonium borofluorides or sultones.

The method of preparation of some compounds is described in detail below.

Compound 1 (as fluoborate) 10 mmol of 1,5-diazanaphthalene and 40 mmol (5.9 g) of trimethyloxonium fluoborate are together stirred in 50 ml of anhydrous ethylene chloride for 20 hours. 5 ml of methanol are then added, and the reaction mixture is briefly stirred, suction filtered, washed with ethylene chloride and recrystallized from aqueous ethanol. The fluoborate analog of compound 1 is obtained in percent yield. The decomposition point is 280C. Compound 2 1.3 g of 1,5-diazanaphthalene and 10 ml of diethyl sulfate are heated on a water bath for 12 hours with exclusion of moisture. After cooling, the precipitate is removed by suction filtration, pressed on clay and washed with acetone. Decomposition point above 170C.

Compound 3 1.3 g of 1,5-diazanaphthalene and 6.1 g of propane sultone are heated to C for 5 hours. The mixture is then left' to cool and digested with isopropanol. The residue is recystallized from water. The compound decomposes above 250C.

The other compounds are prepared similarly.

The bleaching catalysts according to the invention are added to the bleach bath in amounts of between 0.005 and 0.200 g/l.

The effect of the bath according to the invention is substantially independent of the nature of the azo dye insofar as any given azo dye is bleached much more rapidly than with conventional baths. The bath according to the invention may, therefore, be used quite generally for the silver dye bleaching process regardless of the nature of the dye used. 5

The materials which are to be processed in the baths according to the invention are prepared in a known manner. The azo dyes in the silver halide emulsion layers may be e.g., those described in the following patent specifications:

German Pat. specifications Nos. 1,257,568; 1,246,404; 1,300,827 and 1,284,299 and British Pat. specifications Nos. 1,134,394; 1,146,118; 1,146,406 and 1,178,424(

The other stages of the process may also be carried out in the usual manner, e.g., as follows:

1. Development 5 minutes in a bath of 1 g of pmethylamino phenol, 3 g of hydroquinone, 13 g of anhydrous sodium sulfite, 1 g of sodium bromide, 26 g of anhydrous sodium carbonate, made up to 1,000 ml with water.

2. Wash 5 minutes.

3. Fix 5 minutes in a bath of 200 g of sodium thiosulfate cryst. and 20 g of potassium metabisulfite made up to 1,000 ml with water.

4. Wash 5 minutes.

5. Harden 5 minutes in a bath of 100 ml of 30 percent formalin and 2 g of sodium bicarbonate made up to 1,000 ml with water.

6. Wash 5 minutes.

7. Dye bleaching.

8. Wash 5 minutes.

9. Bleach fixing for 10 minutes in a bath of 26 g of tetrasodium ethylene diaminotetraacetate, 24 g anhydrous sodium carbonate 15 g of iron (Ill) chloride, 13 g of anhydrous sodium sulfite, and 200 g of sodium thiosulfate made up to 800 ml with water.

10. Wash 20 minutes.

The dye bleaching baths according to the invention have a pH of at the most 2 and preferably between and 1. The required pH range is adjusted by the addition of inorganic or organic acids, e.g., sulfuric acid, hydrohalic acids such as hydrochloric acid or hydrobromic acid, phosphoric acid, nitric acid, toluene sulfonic acid or naphthylene disulfonic acid.

The silver salt forming agents used may be potassium halides or other alkali metal halides, preferably iodides such as potassiumiodide.

The following may be used as silver complex forming agents: thiosemicarbazide or preferably thiourea or its derivatives.

Especially advantagous results are obtained by mixing potassium iodide with thiourea.

The silver salt forming agents are advantageously used in quantities of between 10 and 50 g/l and the complex forming agents in quantities of from 10 to 200 EXAMPLE 1 A light-sensitive photographic material for the silver dye bleaching process, consisting substantially of a redsensitive silver bromide gelatin emulsion layer containing a cyan azo dye and mounted on a support, a greensensitive silver bromide gelatin emulsion layer containing a magenta azo dye, a yellow filter layer and an uppermost blue-sensitive silver bromide gelatin emulsion layer containing a yellow azo dye, is exposed to white light behind a grey step wedge. Six samples arethen processed as follows:

1. Development minutes in a bath of:

l g of p-methylamino phenol,

3 g of hydroquinone,

13 g of anhydrous sodium sulfite,

1 of sodium bromide, and

26 g of anhydrous sodium carbonate, made up to 1 litre with water; 2. Washing 5 minutes; 3. Hardening 5 minutes in a bath of:

60 ml of 30 percent formalin and 15 g of sodium bicarbonate made up to 1 litre with water; 4. Washing 5 minutes.

The developed and hardened material is then treated in the following stages, each sample being bleached in a different one of bleaching baths 1 to 6 as described below;

5. Dye bleaching; 6. Washing 10 minutes.

Subsequent processing was then the same for all six sample strips.

7. Bleach fixing for 10 minutes in a bath of:

26 g of tetrasodium ethylene diaminotetraacetate,

24 g of anhydrous sodium carbonate 15 g of iron (III) chloride,

13 g of anhydrous sodium sulfite and 200 g of sodium thiosulfate made up to 800 ml with water; 8. Washing 20 minutes.

The various bleaching baths contain per litre:

Concentrated sulfuric acid 100 g Nal-l PO -H o 5 g Potassium iodide 10 g Bleaching catalysts in the quantities shown in the following table.

The temperature of the dye bleaching bath is 30C, the

treatment time 10 minutes.

TABLE Catalyst bleaching bleaching molar bath quantity equivalents 1 0.075 g 1 1,5

diazanaphthalene 2 0.013 g l/l6 compound 1 3 0.0315 g l/8 compound 2 4 0.108 g l/2 compound 3 5 0.079 g 1/4 compound 4 6 0.018 g l/l2 compound 5 The sensitometer strips obtained from all six samples are identical in appearance in spite of the considerable differences in concentration of the catalyst between comparison test 1 in which unsubstituted 1,5- diazanaphthalene was used and those in which bleaching baths (2) to (6) according to the invention were used.

It follows from the experiments that 1,5- diazanaphthalene, which is difficult to obtain, can be converted nearly quantitatively by an alkylating reaction into highly active products which, when used in the same or equivalent quantities, enable the dye bleaching time to be considerably reduced or, when used for the same or even a shorter length of time, enable a considerable saving in bleaching catalyst to be obtained. In the case of the dimethylation product, this saving amounts to more than percent.

. EXAMPLE 2 A light-sensitive photographic material for the silver dye bleaching process, consisting substantially of a supported red-sensitive silver bromide gelatin emulsion which contains a cyan azo dye, a green-sensitive silver bromide gelatin emulsion layer containing a magenta azo dye, a yellow filterlayer and an uppermost bluesensitive silver bromide emulsion layer containing a yellow azo dye, is exposed to white light behind a grey step wedge. Eight samples are then processed as follows: 1. Development 5 minutes in a bath of:

l g of p-methylamino phenol 3 g of hydroquinone,

13 g of anhydrous sodium sulfite,

l g of sodium bromide and 26 g of anhydrous sodium carbonate made up to 1 litre with water; 2. Washing 5 minutes; 3. Hardening 5 minutes in a bath of:

60 ml of 30 percent formalin and 15 g of sodium bicarbonate, made up to 1 litre with water; 4. Washing 5 minutes; 5. The developed and hardened material is then treated in the following stages, using the two bleaching baths (7) and (8) and bleaching being carried out at 30C 'for 2%, 5, 7% and 10 minutes, each sample being subjected to a different bleaching combination. 6. Washing 10 minutes; 7. Bleach fixing for 10 minutes in a bath of:

26 g of tetrasodium ethylene diaminotetraacetate,

24 g of anhydrous sodium carbonate g of iron(lII) chloride,

13 g of anhydrous sodium sulfite, and

200 g of sodium thiosulphate, made up to 800 ml with water; 8. Washing minutes.

Bleaching baths (7) and (8) contain, per litre:

Concentrated sulfuric acid 100 g Sodium hypophosphite 5 g Potassium iodide 10 g and:

' bleaching bath (7) 0.075 g of 1,5-diazanaphthalene bleaching bath (8) 0.208 g of compound (1 The sensitometer strips obtained show that dye bleaching bath 8) is much more active than bath (7) which contains the same molar quantity of catalyst. The sample which has been bleached for 2% minutes in bath (8) is identical with the sample which has been bleached for 7% minutes in bath (7). The sample which has been bleached for 5 minutes in bath (8) is much more strongly bleached than the sample which has been bleached for 10 minutes in bath (7).

EXAMPLE 3 The procedure is the same as described in Example 2 but using dye bleaching baths (7) and (9). Bleaching bath (9) differs from bleach bath (8) only by its smaller quantity (0.075 g) of compound (l).

A comparison of the sensitometer strips obtained shows that the sample which has been bleached for 2 minutes in bath (9) is more strongly bleached than the sample which has been bleached for 5 minutes in bath (7).

The results of the comparison tests are represented in the figure. The curves show the y-value of the cyan part of the image as modified by the action of the dye bleaching baths. The ordinate represents the density and the abscissa the log 1.! value. The broken line curves 1, 2, 3 and 4 show the efficiency of dye bleaching bath (7) acting for 2 5, 7 and 10 minutes, respectively. The continuous line curves 1' to 4 represent the results obtained after the same time with bleaching bath (9).

What we claim is:

1. In a catalyst-containing aqueous dye bleaching bath for the silver dye bleaching process, the improvement according to which the catalyst is a substituted 1,5-diazanaphthalene of the following formula:

wherein R and R each represents a saturated or olefinically unsaturated aliphatic group having up to five carbons, which may be substituted with halogen, hydroxyl, alkoxy, carboxyl, sulfo or sulfato; and R and R combined may contain n acid groups X represents any photographically inert anion; and

n is 0, l or 2.

2. The combination of claim 1 in which the concentration of the bleaching catalyst is between 5 and 200 mg/ 1.

3. The combination of claim 1 in which the bath has a pH of between 0 and l.

4. The combination of claim 1 in which the bath contains potassium iodide as a silver-salt-forrning agent.

5. The combination of claim 1 in which the bath contains a thiourea silver-complex-forming agent.

6. in the process for the production of photographic images by means of the silver dye bleaching process, the improvement according to which the dye bleaching bath used is the bath of claim 1.

7. The combination of claim 2 in which the bath has a pl-l of between 0 and l.

t t t t i

Claims

2. The combination of claim 1 in which the concentration of the bleaching catalyst is between 5 and 200 mg/1.
3. The combination of claim 1 in which the bath has a pH of between 0 and 1.
4. The combination of claim 1 in which the bath contains potassium iodide as a silver-salt-forming agent.
5. The combination of claim 1 in which the bath contains a thiourea silver-complex-forming agent.
6. In the process for the production of photographic images by means of the silver dye bleaching process, the improvement according to which the dye bleaching bath used is the bath of claim 1.
7. The combination of claim 2 in which the bath has a pH of between 0 and 1.