EP0430000A1 - Bleach bath - Google Patents

Abstract

A readily biodegradable bleach bath having an adequate bleaching action contains (1) an iron(III) complex, whose complexing agent corresponds to the extent of at least 20 mol %, preferably at least 80 mol %, to the formula I <IMAGE> in which R2 is hydrogen or hydroxyl, n is 1 or 2, x is 2 or 3 and y is 0 or 1 and the total of x and y is always 3, (2) an excess of free complexing agent from 1 to 120 mol %, preferably from 5 to 20 mol %, relative to the iron complex or iron complex salt, and has been (3) adjusted to a pH value of </= 4.5.

Description

The invention relates to a bleaching bath which is suitable for processing color photographic silver halide materials and which is particularly environmentally friendly.

Iron complex salts of aminopolycarboxylic acids, for example the iron ammonium complex salt of ethylenediaminetetraacetic acid, are usually used to bleach the silver formed during the development of color photographic materials. This and similar complexing agents that are also used are only very slowly biodegradable.

If bleaching baths containing iron complexes of readily biodegradable complexing agents such as nitrilotriacetic acid are used for bleaching color photographic materials under the usual conditions at pH 6 to 8, they lack sufficient bleaching capacity.

The object of the invention was to provide a bleaching bath which is suitable for processing color photographic silver halide materials and which contains readily biodegradable constituents and has a sufficient bleaching effect.

entspricht, worin

R₁

Wasserstoff oder Hydroxy,

n

1 oder 2

x

2 oder 3 und

y

0 oder 1

bedeuten und die Summe aus x und y stets 3 ist, und

• (2) einen Überschuß an freiem Komplexbildner von 1 bis 120 Mol-%, vorzugsweise von 5 bis 20 Mol-%, bezogen auf den Eisenkomplex oder das Eisenkomplexsalz enthält, und
• (3) auf einen pH-Wert ≦ 4,5 eingestellt ist.

This object is achieved with a bleaching bath containing (1) an iron (III) complex, the complexing agent of which is at least 20 mol%, preferably at least 80 mol%, of the formula I.

corresponds to what

R₁

Hydrogen or hydroxy,

n

1 or 2

x

2 or 3 and

y

0 or 1

mean and the sum of x and y is always 3, and

• (2) contains an excess of free complexing agent from 1 to 120 mol%, preferably from 5 to 20 mol%, based on the iron complex or the iron complex salt, and
• (3) is set to a pH ≦ 4.5.

Pure substances, but also mixtures, can be used as complexing agents of the formula (I).

Preferred compounds within the formula I are nitrilotriacetic acid and nitrilomonopropionediacetic acid of the formulas



N- (CH₂COOH) ₃ and




(HOOC) -CH₂) ₂-N-CH₂-CH₂-COOH.

The remaining at most 80 mol%, or preferably at most 20 mol%, of complexing agent can be conventional complexing agents such as ethylenediaminetetraacetic acid or propylenediaminetetraacetic acid. Only the complexing agents according to the invention are preferably used.

In particular 0.005 to 0.5 mol / l of iron complex or iron complex salt are used.

In addition to the components according to the invention, bleaching baths also contain a halide for rehalogenating the silver.

The halides of the bleaching baths are in particular the chlorides and bromides of sodium, potassium and ammonium.

When ready for use, the bleach bath contains 0.05 to 1.5 mol / l halide.

The bleaching bath according to the invention is particularly suitable for color photographic silver halide recording materials whose silver halide emulsions consist predominantly of AgBr, AgBrI, AgBrCl or AgCl. The color photographic material preferably contains on a reflective or transparent support (for example paper coated on both sides with polyethylene or cellulose triacetate film) at least one blue-sensitive, at least one green-sensitive and at least one red-sensitive silver halide emulsion layer, to which at least one yellow coupler, at least one magenta coupler and at least one cyan coupler in the order given assigned.

The bleaching bath according to the invention is used within the usual processing method for color photographic silver halide materials, which consists of the steps of imagewise exposure, development, optionally stopping, bleaching, fixing or bleach-fixing, watering, optionally stabilizing and drying, the watering being omitted if at the end of Processing a stabilizing bath is applied.

The processing method can be carried out continuously with constant regeneration of the individual processing baths.

The bleaching baths listed in the examples were examined for their bleaching behavior (residual silver in the processed material).

Residual silver determination:

The exposed step wedge of the photographic material, which was subsequently processed as described below, was examined for residual silver in the image blackness using an infrared silver detector PM 8030 from Photo-Matic, Denmark.

The publication: Nitrilotriacetic acid, BUA substance report 5 (October 1986), published by the Federal Committee for Environmentally Relevant Waste Materials (BUA) of the Gesellschaft Deutscher Chemiker, Verlag Chemie, Weinheim 1987, provides information on the biodegradability of the complexing agent used in the bleaching bath according to the invention.

Example 1

A color photographic recording material was produced by applying the following layers in the order given to a support on paper coated on both sides with polyethylene. The quantities given relate to 1 m ² . For the silver halide application, the corresponding amounts of AgNO₃ are given.

Layer structure

• 1st layer (substrate layer):
  0.2 g gelatin
• 2nd layer (blue-sensitive layer):
  blue-sensitive silver halide emulsion (99.5 mol% chloride, 0.5 mol% bromide, average grain diameter 0.8 µm) from 0.63 g AgNO₃ with
  1.38 g gelatin
  0.95 g yellow coupler Y
  0.29 g tricresyl phosphate (CPM)
• 3rd layer (protective layer)
  1.1 g gelatin
  0.06 g 2,5-dioctylhydroquinone
  0.06 g dibutyl phthalate (DBP) 4th layer (green-sensitive layer)
  green-sensitized silver halide emulsion (99.5 mol% chloride, 0.5 mol% bromide, average grain diameter 0.6 µm) from 0.45 g AgNO₃ with
  1.08 g gelatin
  0.41 g purple coupler M
  0.08 g 2,5-dioctyl hydroquinone
  0.34 g DBP
  0.04 g CPM
• 5th layer (UV protective layer)
  1.15 g gelatin
  0.6 g UV absorber of the formula
  
  0.045g 2,5-dioctyl hydroquinone
  0.04 g CPM
• 6th layer (red-sensitive layer)
  Red-sensitized silver halide emulsion (99.5 mol% chloride, 0.5 mol% bromide, average grain diameter 0.5 µm) from 0.3 g AgNO₃ with
  0.75 g gelatin
  0.36 g cyan coupler C
  0.36 g CPM
• 7th layer (UV protective layer)
  0.35 g gelatin
  0.15 g UV absorber according to the 5th layer
  0.2 g CPM
• 8th layer (protective layer)
  0.9 g gelatin
  0.3 g of curing agent H of the following formula

The components used have the following formula:

Die einzelnen Verarbeitungsbäder hatten die folgende Zusammensetzung:

Ergebnis der Restsilberbestimmung siehe Tab. 1.A step wedge was exposed on the photographic material described above and processed as follows:

The individual processing baths had the following composition:

For the result of the residual silver determination, see Tab. 1.

Example 2 (comparison)

Fixierbad wie Beispiel 1The exposure and processing were carried out as described in Example 1. The developer had the same composition as in Example 1.

Fixing bath as in example 1

Result of the residual silver determination: see Table 1.

Example 3 (comparison)

Fixierbad wie Beispiel 1The exposure and processing were carried out as described in Example 1. The developer had the same composition as in Example 1.

Fixing bath as in example 1

Tabelle 1 zeigt die gute Bleichwirkung des erfindungsgemäßen Bleichbades A, in dem ein biologisch abbaubarer Komplexbildner enthalten ist. Die Bleichwirkung entspricht der des üblichen Bleichbades C, das die biologisch schwer abbaubare EDTA enthält. Das Bleichbad B, das im wesentlichen wie Bleichbad A zusammengesetzt ist, aber in dem für EDTA-Bleichbäder vorgeschriebenen pH-Bereich liegt, bleicht dagegen nur ungenügend.Result of the residual silver determination: see Table 1.

Table 1 shows the good bleaching action of the bleaching bath A according to the invention, which contains a biodegradable complexing agent. The bleaching effect corresponds to that of the usual bleaching bath C, which contains the biodegradable EDTA. The bleaching bath B, which is composed essentially like bleaching bath A, but lies in the pH range prescribed for EDTA bleaching baths, on the other hand only bleaches insufficiently.

Example 4

The following layers were each applied to a transparent cellulose triacetate support in the order given here.

The quantities given relate to 1 m². For the silver halide application, the equivalent amounts of AgNO₃ are given.

All silver halide emulsions were stabilized with 0.1 g of 4-hydroxy-6-methyl-1,3,3a, 7-tetraazaindene per 100 g of AgNO₃.

1st layer : (antihalo layer)

0.2 g black colloidal silver
1.2 g gelatin
0.1 g UV absorber UV 1
0.2 g UV absorber UV 2
0.02 g tricresyl phosphate
0.03 g dibutyl phthalate

2nd layer : (intermediate layer )

0.25 g AgNO₃ a Mikrat-Ag (Br, J) emulsion: average grain ø = 0.07 µm, 0.5 mol% iodide
1.0 g gelatin
0.05 g colored coupler RM 1

0.10 g tricresyl phosphate

3rd layer : (low sensitive red-sensitive layer)

2.2 g AgNO₃, 4 mol% iodide, average grain diameter 0.45 µm, red-sensitized
2.0 g gelatin
0.6 g colorless cyan coupler C 1 emulsified in 0.5 g tricresyl phosphate (TKP)
50 mg colored cyan couplers RM 1 and
30 mg DIR coupler DIR 1 emulsifies in 20 mg CPM.

4th layer : (highly sensitive red-sensitized layer)

2.8 g AgNO₃, 8.5 mol% iodide, average grain diameter 0.8 µm, red-sensitized
1.8 g gelatin
0.15 g colorless cyan coupler C 2 emulsified with 0.15 g dibutyl phthalate (DBP)

5th layer : (separation layer)

0.7 g gelatin
0.2 g of 2,5-diisooctyl hydroquinone emulsified with 0.15 g of DBP

6th layer : (low-sensitivity green-sensitized layer)

1.8 g AgNO₃ of a spectrally green-sensitized Ag (Br, I) emulsion with 4.5 mol% iodide and an average grain diameter of 0.4 µm, green-sensitized,
1.6 g gelatin
0.6 g purple coupler M 1 (latex coupler)
50 mg mask coupler YM 1
emulsified with 50 mg CPM,
30 mg DIR coupler DIR 2
emulsified in 20 mg DBP
80 mg DIR coupler DIR 3
emulsified in 60 mg CPM

7th layer (highly sensitive green-sensitized layer)

2.2 g AgNO₃ with 7 mol% iodide and an average grain diameter of 0.7 µm, green-sensitized,
1.4 g gelatin
0.15 g purple coupler M 2
emulsified with 0.45 g CPM
30 mg mask coupler according to 6th layer,
emulsified with 30 mg CPM

8th layer : (separation layer)

0.5 g gelatin
0.1 g of 2,5-diisooctyl hydroquinone
emulsified with 0.08 g DBP

9th layer : (yellow filter layer )

0.2 g Ag (yellow colloidal silver sol)
0.9 g gelatin
0.2 g of 2,5-diisooctyl hydroquinone
emulsified with 0.16 g DBP

10th layer : (low-sensitivity blue-sensitive layer)

0.6 g AgNO₃, 4.9 mol% iodide, average grain diameter 0.45 µm, blue-sensitized,
0.85 g gelatin
0.7 g yellow coupler Y 1
emulsified with 0.7 g CPM,
0.5 g DIR coupler DIR 3
emulsified with 0.5 g CPM

11th layer : (highly sensitive blue-sensitive layer

1.0 g AgNO₃, 9.0 mol% iodide, average grain diameter 0.9 µm, blue-sensitized,
0.85 g gelatin
0.3 g yellow coupler according to the 10th shift
emulsified with 0.3 g CPM

12th layer : (protective and hardening layer )

Gewichtsverhältnis x : y = 7:3

0.5 g AgNO₃ a Mikrat-Ag (Br, I) emulsion, average grain diameter 0.07 µm, 0.5 mol% iodide
1.2 g gelatin
0.4 g hardening agent of the formula



(CH₂ = CH-SO₂-CH₂-CONH-CH₂-) ₂-



1.0 g formaldehyde scavenger of the formula

Weight ratio x: y = 7: 3

Die Verarbeitungsbäder hatten die folgende Zusammensetzung:

Das Ergebnis bezüglich Restsilber ist der nachfolgenden Tabelle 2 zu entnehmen. Das erzeugte Farbbild war typgemäß.A step wedge was exposed on the photographic material described above and processed as follows:

The processing baths had the following composition:

The result with regard to residual silver is shown in Table 2 below. The color image produced was of the type.

Example 5 (comparison)

The exposure and processing were carried out as described in Example 4. Developer, fixer and final bath had the same composition as in Example 4.

The result of the residual silver determination is shown in Table 2 below.

Example 6 (comparison)

The exposure and processing were carried out as described in Example 4. Developer, fixer and final bath had the same composition as in Example 4.

Wie aus Tabelle 2 zu ersehen ist, entspricht die Bleichwirkung des erfindungsgemäßen Bleichbades D mit einem biologisch abbaubaren Komplexbildner der Bleichwirkung des üblichen Bleichbades F mit dem biologisch schwer abbaubaren Komplexbildner EDTA. Das Bleichbad E, das im wesentlichen wie Bleichbad D zusammengesetzt ist, aber einen für EDTA-Bleichbäder üblichen pH-Wert besitzt, bleicht dagegen nur ungenügend. Die durchgeführten Bleichversuche zeigten, daß das erfindungsgemäße Bleichbad D nicht zur Bildung von Leuco-Blaugrünfarbstoff führt, während bei einem üblichen Bleichbad mit EDTA bei entsprechendem pH-Wert deutliche Verluste an Blaugrünfarbstoff auftreten.The result with regard to residual silver is shown in Table 2 below.

As can be seen from Table 2, the bleaching action of the bleaching bath D according to the invention with a biodegradable complexing agent corresponds to the bleaching action of the customary bleaching bath F with the biodegradable complexing agent EDTA. The bleaching bath E, which is composed essentially like bleaching bath D, but has a pH value customary for EDTA bleaching baths, on the other hand only bleaches insufficiently. The bleaching tests carried out showed that the bleaching bath D according to the invention does not lead to the formation of leuco blue-green dye, while in a conventional bleaching bath with EDTA there are significant losses of blue-green dye at the corresponding pH.

Claims (4)

Bleaching bath containing (1) an iron (III) complex whose complexing agent contains at least 20 mol% of the formula I.

corresponds to what R₁ is hydrogen or hydroxy, n 1 or 2 x 2 or 3 and y 0 or 1 mean and the sum of x and y is always 3, and (2) contains an excess of free complexing agent from 1 to 120 mol% based on the iron complex or the iron complex salt, and (3) is set to a pH ≦ 4.5. Bleaching bath according to claim 1, the complexing agent of which corresponds to at least 80 mol% of formula I. A bleaching bath according to claim 1, wherein the complexing agent is nitrilotriacetic acid or nitrolomonopropionediacetic acid. Bleaching bath according to claim 1 with an excess of free complexing agent from 5 to 20 mol%.