PERSULFATE BLEACH-FIX SOLUTION
United States Patent 3772020
Bleach-fix solutions utilizing a water-soluble persulfate as the silver oxidizing agent and an alkyl amino alkyl thiol as the fixing agent are described.
US Patent References:
SILVER NITRATE STAIN REMOVAL COMPOSITION AND METHOD FOR USING SAME
Columbo - March 1969 - 3434796
SILVER NITRATE STAIN REMOVAL COMPOSITION AND METHOD FOR USING SAME
Columbo - March 1969 - 3434796
Application Number:
05/200614
Publication Date:
11/13/1973
Filing Date:
11/19/1971
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Export Citation:
Assignee:
Eastman Kodak Company (Rochester, NY)
Primary Class:
Other Classes:
252/186.380
International Classes:
G03C7/42; G03C5/32
Field of Search:
252/186 96/6BF,60,61
Primary Examiner:
Welsh, John D.
Claims:
I claim
1. A bleach-fix composition for use in processing of photographic elements, said composition comprising a water-soluble persulfate bleaching agent and a fixing agent of the formula: ##SPC6##
2. A composition as claimed in claim 1 wherein the concentration of said bleaching agent is from about 0.05 to about 0.5 moles per liter and the concentration of said fixing agent is from about 0.1 to about 2.0 moles per liter.
3. A composition as claimed in claim 1 wherein the concentration of said bleaching agent is from about 0.1 to about 0.4 moles per liter and the concentration of said fixing agent is from about 0.13 to about 1.5 moles per liter.
4. A composition as claimed in claim 1 wherein said bleaching agent is selected from the group consisting of potassium persulfate, sodium persulfate and ammonim persulfate.
5. A composition as claimed in claim 1 wherein R1 and R2 are CH3 or C2 H5 and n is 2 or 3.
6. A composition as claimed in claim 1 wherein said bleaching agent is potassium persulfate and said fixing agent is 2,2-diethylaminoethanethiol.
7. In a method of photographic processing wherein an exposed photographic element is treated with a bleach-fixing solution containing both a bleaching agent and a fixing agent, the improvement wherein said bleaching agent is a water-soluble persulfate and said fixing agent is a compound of the formula: ##SPC7##
8. A method as claimed in claim 7 wherein the concentration of said bleaching agent is from about 0.05 to about 0.5 moles per liter and the concentration of said fixing agent is from about 0.1 to about 2.0 moles per liter.
9. A method as claimed in claim 7 wherein the concentration of said bleaching agent is from about 0.1 to about 0.4 moles per liter and the concentration of said fixing agent is from about 0.13 to about 1.5 moles per liter.
10. A method as claimed in claim 7 wherein said bleaching agent is selected from the group consisting of potassium persulfate, sodium persulfate and ammonium persulfate.
11. A method as claimed in claim 7 wherein R1 and R2 are CH3 or C2 H5 and n is 2 or 3.
12. A method as claimed in claim 7 wherein said bleaching agent is potassium persulfate and said fixing agent is 2,2-diethylaminoethanethiol.
13. A method of color processing an exposed photographic element comprising the steps of color development, stop-fixing, and bleach-fixing in solution containing a water-soluble persulfate bleaching agent and a fixing agent of the formula: ##SPC8## wherein R1 and R2 are selected from the group consisting of H, CH3, C2 H5 and C3 H7 and n is an integer of from 1 to 4.
14. A method as claimed in claim 13 wherein the concentration of said bleaching agent is from about 0.05 to about 0.5 moles per liter and the concentration of said fixing agent is from about 0.1 to about 2.0 moles per liter.
15. A method as claimed in claim 13 wherein the concentration of said bleaching agent is from about 0.1 to about 0.4 moles per liter and the concentration of said fixing agent is from about 0.13 to about 1.5 moles per liter.
16. A method as claimed in claim 13 wherein said bleaching agent is selected from the group consisting of potassium persulfate, sodium persulfate and ammonium persulfate.
17. A method as claimed in claim 13 wherein R1 and R2 are CH3 or C2 H5 and n is 2 or 3.
18. A method as claimed in claim 13 wherein said bleaching agent is potassium persulfate and said fixing agent is 2,2-diethylaminoethanethiol.
1. A bleach-fix composition for use in processing of photographic elements, said composition comprising a water-soluble persulfate bleaching agent and a fixing agent of the formula: ##SPC6##
2. A composition as claimed in claim 1 wherein the concentration of said bleaching agent is from about 0.05 to about 0.5 moles per liter and the concentration of said fixing agent is from about 0.1 to about 2.0 moles per liter.
3. A composition as claimed in claim 1 wherein the concentration of said bleaching agent is from about 0.1 to about 0.4 moles per liter and the concentration of said fixing agent is from about 0.13 to about 1.5 moles per liter.
4. A composition as claimed in claim 1 wherein said bleaching agent is selected from the group consisting of potassium persulfate, sodium persulfate and ammonim persulfate.
5. A composition as claimed in claim 1 wherein R1 and R2 are CH3 or C2 H5 and n is 2 or 3.
6. A composition as claimed in claim 1 wherein said bleaching agent is potassium persulfate and said fixing agent is 2,2-diethylaminoethanethiol.
7. In a method of photographic processing wherein an exposed photographic element is treated with a bleach-fixing solution containing both a bleaching agent and a fixing agent, the improvement wherein said bleaching agent is a water-soluble persulfate and said fixing agent is a compound of the formula: ##SPC7##
8. A method as claimed in claim 7 wherein the concentration of said bleaching agent is from about 0.05 to about 0.5 moles per liter and the concentration of said fixing agent is from about 0.1 to about 2.0 moles per liter.
9. A method as claimed in claim 7 wherein the concentration of said bleaching agent is from about 0.1 to about 0.4 moles per liter and the concentration of said fixing agent is from about 0.13 to about 1.5 moles per liter.
10. A method as claimed in claim 7 wherein said bleaching agent is selected from the group consisting of potassium persulfate, sodium persulfate and ammonium persulfate.
11. A method as claimed in claim 7 wherein R1 and R2 are CH3 or C2 H5 and n is 2 or 3.
12. A method as claimed in claim 7 wherein said bleaching agent is potassium persulfate and said fixing agent is 2,2-diethylaminoethanethiol.
13. A method of color processing an exposed photographic element comprising the steps of color development, stop-fixing, and bleach-fixing in solution containing a water-soluble persulfate bleaching agent and a fixing agent of the formula: ##SPC8## wherein R1 and R2 are selected from the group consisting of H, CH3, C2 H5 and C3 H7 and n is an integer of from 1 to 4.
14. A method as claimed in claim 13 wherein the concentration of said bleaching agent is from about 0.05 to about 0.5 moles per liter and the concentration of said fixing agent is from about 0.1 to about 2.0 moles per liter.
15. A method as claimed in claim 13 wherein the concentration of said bleaching agent is from about 0.1 to about 0.4 moles per liter and the concentration of said fixing agent is from about 0.13 to about 1.5 moles per liter.
16. A method as claimed in claim 13 wherein said bleaching agent is selected from the group consisting of potassium persulfate, sodium persulfate and ammonium persulfate.
17. A method as claimed in claim 13 wherein R1 and R2 are CH3 or C2 H5 and n is 2 or 3.
18. A method as claimed in claim 13 wherein said bleaching agent is potassium persulfate and said fixing agent is 2,2-diethylaminoethanethiol.
Description:
This invention relates to bleach-fixing compositions for processing color photographic materials and to a method for the utilization of same.
BACKGROUND OF THE INVENTION
As a general rule the processing of color photographic light sensitive elements is carried out by a process including at least color development, bleaching (silver removal) and fixing followed by washing, post hardening, stabilizing, etc. Various processing compositions dependent upon the types of color photographic light sensitive elements are required in these various processing steps which may, depending upon the nature of the element being processed, be preceded by other steps including prehardening, black and white developing, image reversal, etc.
Typical bleaching compositions for color photographic elements include ferricyanides, ferric chloride and iron ammonium ethylenediamine tetraacetic acid complexes. When an attempt is made to incorporate such bleaching compositions with a fixing agent, for example, thiosulphate or thiocyanate to provide a combined bleach-fixing bath, numerous problems occur. For example, in the case of ferricyanide bleaching agents their combination with a thiosulphate fixing agent results in decomposition of the fixing agent when sufficient bleach is used to achieve satisfactory bleaching.
In the case of iron-EDTA complexes such materials are compatible with the fixing agents, however, the bleaching power of such combined solutions is generally insufficient so that accelerators, which in turn may cause fogging, staining, etc., have to be used.
The successful consolidation of the bleaching and fixing operations utilized in the processing of exposed color photographic elements into a single, simple step has therefor been the goal of skilled artisans in the photographic processing arts for a number of years. Although numerous attempts to achieve this goal have met with varying degrees of success nearly all such systems have met with problems not the least of which are the time involved in such a bleach-fixing operation, the expense involved for chemicals including bleach accelerators, etc., to make such solutions operate effectively, and detrimental affects on image dyes of color photographic materials.
It is therefore an object of the present invention to provide a bleach-fix bath which is rapid, utilizes relatively inexpensive chemicals and does not adversely affect the image dyes of color photographic materials.
These and other objects which will be made clear from a reading of the following specifications are achieved through the use of bleach-fix baths containing a water soluble persulfate as the bleaching agent and bleach accelerators having the following generic formula: ##SPC1##
Wherein R 1 and R 2 are selected from the group consisting of H, CH 3 , C 2 H 5 , and C 3 H 7 and n is an integer from 1 to 4. Specifically preferred among this class of accelerators are those compounds wherein R 1 and R 2 are selected from the group consisting of CH 3 and C 2 H 5 and n is either 2 or 3. Especially advantageous results have been achieved when potassium persulfate (K 2 S 2 O 8 ) is used as the bleaching agent, and the above-described preferred accelerators also serve as the fixing agent.
The present invention also provides an improved method of color processing color photographic light sensitive elements comprising, at least, the steps of color development, stop-fixing and bleach-fixing comprising processing the light sensitive element in a bath containing a water-soluble persulfate, preferably potassium persulfate, and a compound represented by the general formula: ##SPC2##
wherein R 1 and R 2 are selected from the group consisting of H, CH 3 , C 2 H 5 , and C 3 H 7 and n is an integer from 1 to 4.
DETAILED DESCRIPTION OF THE INVENTION
The bleaching solutions of the present invention generally comprise aqueous solutions of a water-soluble persulfate salt as the bleaching agent, i.e., an alkali metal or ammonium persulfate, and at least one bleach accelerator which also serves as fixing agent selected from the group of compounds having the generic formula: ##SPC3##
wherein R 1 and R 2 are selected from the group consisting of H, CH 3 , C 2 H 5 , and C 3 H 7 and n is an integer from 1 to 4. Specifically preferred among these accelerators are those wherein R 1 and R 2 are selected from the group consisting of CH 3 and C 2 H 5 and n is either 2 or 3. Potassium persulfate has proven particularly effective as the bleaching agent.
The concentration of the persulfate oxidizing agent in the bleach-fix solutions of this invention ranges from about 0.05 to about 0.5 moles per liter of solution and preferably between about 0.1 and 0.4 moles per liter. The concentration of the alkyl thiol fixing agent ranges from about 0.1 to about 2.0 moles per liter of solution and preferably from about 0.13 to about 1.5 moles per liter of solution.
The following discussion is divided into three parts each of which has a specific goal as described immediately hereinafter:
Part A relates to the evaluation of thiol derivatives other than alkylaminoalkylthiols in a bleach-fix composition wherein the bleaching agent is potassium persulfate.
Part B relates to the evaluation of oxidizing agents other than persulfate in a bleach-fix composition wherein the fixing agent is diethylaminoethane thiol.
Part C relates to the evaluation of homologs of diethylaminoethane thiol in a bleach-fix composition wherein the bleaching agent is potassium persulfate.
Part A
Five samples of Eastman Color Print Film (Type 5385) were sensitometrically exposed to a graduated-density test object (step tablet), color developed, acid-stopped, washed and dried in conventional fashion. The infra-red (IR) density of the developed, silver in each step is recorded in column 1 of Table I. The quantity of silver-plus-silver halide (in mg/ft 2 of coating) present in each step, as determined by quantitivative analytical silver analysis, is recorded in column 1a of Table I.
Five additional samples of the same film were similarly exposed, color developed, acid-stopped, washed and then bleach-fixed for 90 seconds respectively in Solutions A, B, C, D and E, whose compositions are given below. The samples were finally washed and dried.
Solution A K 2 S 2 O 8 50 g 2, 2-Diethylaminoethanethiol . HCl (.25 mole) (H 5 C 2 ) 2 NCH 2 CH 2 SH . HCl (Cpd. A) 50 g H 2 O to 1 liter (.338 mole) Solution B K 2 S 2 O 8 50 g (.25 mole) Mercaptoacetic acid, Sodium Salt 38.5 g NaOOCCH 2 SH (Cpd. B) (.33 mole) H 2 O to 1 liter Solution C K 2 S 2 O 8 50 g Monothioglycerol (.25 mole) (OH) 2 CHCH 2 CH 2 SH (Cpd. C) 100 ml H 2 O to 1 liter (1.29 mole) Solution D K 2 S 2 O 8 50 g L-(+)-Cysteine . HCl (.25 mole) HSCH 2 CHNH 2 COOH . HCl . H O (Cpd. D) 59.3 g H 2 O to 1 liter (.33 mole) Solution E K 2 S 2 O 8 50 g 1H,1,2,4-Trianzol-3-thiol (.25 mole) ##SPC4##
10 g (.1 mole) H 2 O to 1 liter
The IR-densities and analytically determined Ag + AgX coverages in each of the image steps of the so processed samples are recorded in columns 2/2a, 3/3a, 4/4a, 5/5a and 6/6a in Table I. ##SPC5##
The data in Table I indicate that Solution A effectively bleached and fixed the silver and silver halide in the photographic element; Solution B showed very little effect in regard to both bleaching and fixing; Solutions C, D and E bleached only some of the initially present silver, and they were rather ineffective in regard to their fixing action.
The combination of an oxidizing agent such as K 2 S 2 O 8 and the fixing agent, 2,2-diethylaminoethanethiol as components in a bleach-fix solution appears from this data to be unique.
Part B
A sample of a conventional supported light-sensitive gelatinous silver halide coating was flash-exposed and developed. The infra-red (IR) density of the developed silver was measured to be 2.96. The quantity of silver-plus-silver halide was found to be 182 mg per square foot of coating. These two values are recorded in the first line of Table II.
Three other samples were exposed and developed similarly, and then treated for 90 seconds in Solutions X, Y and Z respectively.
Solution X K 2 S 2 O 8 50 g (0.25 mole) 2,2-Diethlaminoethanethiol [(H 5 C 2 ) 2 NCH 2 CH 2 SH . HCl] 50 g (0.33 mole) H 2 O to 1 liter Solution Y K 2 Cr 2 O 7 (Potassium dichromate) 75 g (0.25 mole) 2,2-Diethylaminoethane thiol 50 g (0.33 mole) H 2 O to 1 liter Solution Z K 3 Fe(CN) 6 (potassium ferricyanide) 80 g (0.25 mole) 2,2-Diethylaminoethane thiol 50 g (0.33 mole) H 2 O to 1 liter
The three samples were then washed, dried and evaluated by determining the IR Density of the remaining silver and the quantity of silver-plus-silver halide. The results are listed in Table II.
TABLE II
Ag Ag/AgX (IR Dens.) Analysis Untreated Check 2.96 182 Sample treated in Solution X 0.20 58 Sample treated in Solution Y 0.07 107 Sample treated in Solution Z 0.07 172
from the above data it is clear that solution X effectively bleached and fixed the developed sample. Solutions Y and Z effectively bleached the silver, but did not adequately fix the silver halide.
The persulfate therefore appears to be unique as an oxidizing agent in a bleach-fix composition together with an alkylamino alkane thiol fixing agent such as 2,2-diethylaminoethane thiol.
Part C
The procedures described in Part B were repeated with bleach-fix solutions whose compositions are given below. The results are listed in Table III.
solution R K 2 S 2 O 8 50 g/l (0.25 mole) 1-Aminoethanethiol . HCl 37 g/l (0.25 mole) [H 2 NCH 2 CH 2 SH . HCl] H 2 O to 1 liter Solution S K 2 S 2 O 8 50 g/l (0.25 mole) Dimethylaminopropanethiol . HCl [(CH 3 ) 2 N--CH 2 CH 2 CH 2 SH . HCl] 41 g/l (0.25 mole) H 2 O to 1 liter Solution T K 2 S 2 O 8 50 g/l (0.25 mole) Diisopropylaminoethanethiol . HCl [(H 7 C 3 ) 2 N--CH 2 CH 2 SH . HCl] 64.5 g/l (0.25 mole) H 2 O to 1 liter Solution U K 2 S 2 O 8 50 g/l (0.25 mole) Cystamine . 2HCl [(SCH 2 Ch 2 NH 2 ) . 2HCl] 75 g/l (0.25 mole) H 2 O to 1 liter
TABLE III
Ag Ag/AgX IR Dens. Analysis Untreated Check 2.96 181 Samples treated in Solution R .15 182 Sample treated in Solution S .09 37 Sample treated in Solution T .81 59 Sample treated in Solution U .41 177
from this data it appears that solutions S and T effectively bleached and fixed the developed sample. Solutions R and U effectively bleached the silver, but did not adequately fix the silver halide.
Only alkylaminoalkyl thiol homologs of diethylaminoethane thiol appear to be operable fixing agents in a bleach-fix composition according to this invention.
From the above three evaluations it seems clear that aqueous bleach-fix solutions comprising a water-soluble persulfate and alkylaminoalkylthiols exhibit unique properties which are not duplicated in similar solutions containing either different oxidizing agents or fixing agents.
The following examples will serve to further demonstrate the effectiveness of the bleach-fixing solutions of the instant invention and the scope of the invention described herein.
EXAMPLE 1
A sample of Kodak Ektachrome MS Reversal Color Film, Type 2027, was sensitometrically exposed to a multicolor test object, MQ-developed, washed, reversal color developed, washed and bleach-fixed in a 1-liter aqueous solution containing 40 g potassium persulfate and 50 g diethylaminoethanethiol. The sample was completely bleach-fixed in 1.5 minutes at a temperature of 71°F.
EXAMPLE 2
The procedure described in Example 1 was successfully repeated with two similar bleach-fix solutions, wherein the potassium persulfate was replaced with equal molar quantities of sodium persulfate and ammonium persulfate, respectively.
EXAMPLE 3
When the fixing agent in the solution according to Example 1 was replaced with the two other known fixing agents sodium thiocyanate and thiourea, an inoperable bleach-fix was obtained because of the rapid oxidation of the thiocyanate and the thiourea by the persulfate.
The foregoing bleach-fix compositions can, of course, be utilized to treat any conventional silver or silver halide emulsion wherein it is sought to remove unwanted silver and/or silver halide and in conjunction with all of the conventional development, washing, stabilizing, etc., steps described in the discussion of the prior art set forth above. The use of these compositions in such processes is considered an integral part of this invention.
Concentrates of the bleach-fixing solutions described above may of course be prepared to reduce shipping costs incident to the shipping of the solvent (water) or even in dry powder form to increase the storage life only increasing the stability of such concentrates over long periods of time. When prepared as dry powder mixture or as concentrates the ultimate user simply dissolves the powder or concentrate in a suitable amount of water to provide the above-prescribed concentrations in the working bleach-fix solution. Such dry powder mixtures and/or concentrates which are brought to working solution concentration levels at the time of use are therefore to be included within the scope of this disclosure as well as the appended claims.
As should be clear from the foregoing discussion and examples, the alkylaminoalkylthiols of the solution of the present invention may be supplied in the form of acid salts of these materials, for example 2,2-diethylaminoethane thiol HCl, to permit greater ease of dissolution of these materials and increase their availability. When such salts are used, the dissociation products thereof (ie., HCl) will of course be present in the final "working" bleach-fix solution.
The invention has been described in detail with particular reference to preferred embodiments thereof; however, it should be understood that variations and modifications can be made within the spirit and scope of the invention and the same should not be limited except as set forth in the appended claims.
BACKGROUND OF THE INVENTION
As a general rule the processing of color photographic light sensitive elements is carried out by a process including at least color development, bleaching (silver removal) and fixing followed by washing, post hardening, stabilizing, etc. Various processing compositions dependent upon the types of color photographic light sensitive elements are required in these various processing steps which may, depending upon the nature of the element being processed, be preceded by other steps including prehardening, black and white developing, image reversal, etc.
Typical bleaching compositions for color photographic elements include ferricyanides, ferric chloride and iron ammonium ethylenediamine tetraacetic acid complexes. When an attempt is made to incorporate such bleaching compositions with a fixing agent, for example, thiosulphate or thiocyanate to provide a combined bleach-fixing bath, numerous problems occur. For example, in the case of ferricyanide bleaching agents their combination with a thiosulphate fixing agent results in decomposition of the fixing agent when sufficient bleach is used to achieve satisfactory bleaching.
In the case of iron-EDTA complexes such materials are compatible with the fixing agents, however, the bleaching power of such combined solutions is generally insufficient so that accelerators, which in turn may cause fogging, staining, etc., have to be used.
The successful consolidation of the bleaching and fixing operations utilized in the processing of exposed color photographic elements into a single, simple step has therefor been the goal of skilled artisans in the photographic processing arts for a number of years. Although numerous attempts to achieve this goal have met with varying degrees of success nearly all such systems have met with problems not the least of which are the time involved in such a bleach-fixing operation, the expense involved for chemicals including bleach accelerators, etc., to make such solutions operate effectively, and detrimental affects on image dyes of color photographic materials.
It is therefore an object of the present invention to provide a bleach-fix bath which is rapid, utilizes relatively inexpensive chemicals and does not adversely affect the image dyes of color photographic materials.
These and other objects which will be made clear from a reading of the following specifications are achieved through the use of bleach-fix baths containing a water soluble persulfate as the bleaching agent and bleach accelerators having the following generic formula: ##SPC1##
Wherein R 1 and R 2 are selected from the group consisting of H, CH 3 , C 2 H 5 , and C 3 H 7 and n is an integer from 1 to 4. Specifically preferred among this class of accelerators are those compounds wherein R 1 and R 2 are selected from the group consisting of CH 3 and C 2 H 5 and n is either 2 or 3. Especially advantageous results have been achieved when potassium persulfate (K 2 S 2 O 8 ) is used as the bleaching agent, and the above-described preferred accelerators also serve as the fixing agent.
The present invention also provides an improved method of color processing color photographic light sensitive elements comprising, at least, the steps of color development, stop-fixing and bleach-fixing comprising processing the light sensitive element in a bath containing a water-soluble persulfate, preferably potassium persulfate, and a compound represented by the general formula: ##SPC2##
wherein R 1 and R 2 are selected from the group consisting of H, CH 3 , C 2 H 5 , and C 3 H 7 and n is an integer from 1 to 4.
DETAILED DESCRIPTION OF THE INVENTION
The bleaching solutions of the present invention generally comprise aqueous solutions of a water-soluble persulfate salt as the bleaching agent, i.e., an alkali metal or ammonium persulfate, and at least one bleach accelerator which also serves as fixing agent selected from the group of compounds having the generic formula: ##SPC3##
wherein R 1 and R 2 are selected from the group consisting of H, CH 3 , C 2 H 5 , and C 3 H 7 and n is an integer from 1 to 4. Specifically preferred among these accelerators are those wherein R 1 and R 2 are selected from the group consisting of CH 3 and C 2 H 5 and n is either 2 or 3. Potassium persulfate has proven particularly effective as the bleaching agent.
The concentration of the persulfate oxidizing agent in the bleach-fix solutions of this invention ranges from about 0.05 to about 0.5 moles per liter of solution and preferably between about 0.1 and 0.4 moles per liter. The concentration of the alkyl thiol fixing agent ranges from about 0.1 to about 2.0 moles per liter of solution and preferably from about 0.13 to about 1.5 moles per liter of solution.
The following discussion is divided into three parts each of which has a specific goal as described immediately hereinafter:
Part A relates to the evaluation of thiol derivatives other than alkylaminoalkylthiols in a bleach-fix composition wherein the bleaching agent is potassium persulfate.
Part B relates to the evaluation of oxidizing agents other than persulfate in a bleach-fix composition wherein the fixing agent is diethylaminoethane thiol.
Part C relates to the evaluation of homologs of diethylaminoethane thiol in a bleach-fix composition wherein the bleaching agent is potassium persulfate.
Part A
Five samples of Eastman Color Print Film (Type 5385) were sensitometrically exposed to a graduated-density test object (step tablet), color developed, acid-stopped, washed and dried in conventional fashion. The infra-red (IR) density of the developed, silver in each step is recorded in column 1 of Table I. The quantity of silver-plus-silver halide (in mg/ft 2 of coating) present in each step, as determined by quantitivative analytical silver analysis, is recorded in column 1a of Table I.
Five additional samples of the same film were similarly exposed, color developed, acid-stopped, washed and then bleach-fixed for 90 seconds respectively in Solutions A, B, C, D and E, whose compositions are given below. The samples were finally washed and dried.
Solution A K 2 S 2 O 8 50 g 2, 2-Diethylaminoethanethiol . HCl (.25 mole) (H 5 C 2 ) 2 NCH 2 CH 2 SH . HCl (Cpd. A) 50 g H 2 O to 1 liter (.338 mole) Solution B K 2 S 2 O 8 50 g (.25 mole) Mercaptoacetic acid, Sodium Salt 38.5 g NaOOCCH 2 SH (Cpd. B) (.33 mole) H 2 O to 1 liter Solution C K 2 S 2 O 8 50 g Monothioglycerol (.25 mole) (OH) 2 CHCH 2 CH 2 SH (Cpd. C) 100 ml H 2 O to 1 liter (1.29 mole) Solution D K 2 S 2 O 8 50 g L-(+)-Cysteine . HCl (.25 mole) HSCH 2 CHNH 2 COOH . HCl . H O (Cpd. D) 59.3 g H 2 O to 1 liter (.33 mole) Solution E K 2 S 2 O 8 50 g 1H,1,2,4-Trianzol-3-thiol (.25 mole) ##SPC4##
10 g (.1 mole) H 2 O to 1 liter
The IR-densities and analytically determined Ag + AgX coverages in each of the image steps of the so processed samples are recorded in columns 2/2a, 3/3a, 4/4a, 5/5a and 6/6a in Table I. ##SPC5##
The data in Table I indicate that Solution A effectively bleached and fixed the silver and silver halide in the photographic element; Solution B showed very little effect in regard to both bleaching and fixing; Solutions C, D and E bleached only some of the initially present silver, and they were rather ineffective in regard to their fixing action.
The combination of an oxidizing agent such as K 2 S 2 O 8 and the fixing agent, 2,2-diethylaminoethanethiol as components in a bleach-fix solution appears from this data to be unique.
Part B
A sample of a conventional supported light-sensitive gelatinous silver halide coating was flash-exposed and developed. The infra-red (IR) density of the developed silver was measured to be 2.96. The quantity of silver-plus-silver halide was found to be 182 mg per square foot of coating. These two values are recorded in the first line of Table II.
Three other samples were exposed and developed similarly, and then treated for 90 seconds in Solutions X, Y and Z respectively.
Solution X K 2 S 2 O 8 50 g (0.25 mole) 2,2-Diethlaminoethanethiol [(H 5 C 2 ) 2 NCH 2 CH 2 SH . HCl] 50 g (0.33 mole) H 2 O to 1 liter Solution Y K 2 Cr 2 O 7 (Potassium dichromate) 75 g (0.25 mole) 2,2-Diethylaminoethane thiol 50 g (0.33 mole) H 2 O to 1 liter Solution Z K 3 Fe(CN) 6 (potassium ferricyanide) 80 g (0.25 mole) 2,2-Diethylaminoethane thiol 50 g (0.33 mole) H 2 O to 1 liter
The three samples were then washed, dried and evaluated by determining the IR Density of the remaining silver and the quantity of silver-plus-silver halide. The results are listed in Table II.
TABLE II
Ag Ag/AgX (IR Dens.) Analysis Untreated Check 2.96 182 Sample treated in Solution X 0.20 58 Sample treated in Solution Y 0.07 107 Sample treated in Solution Z 0.07 172
from the above data it is clear that solution X effectively bleached and fixed the developed sample. Solutions Y and Z effectively bleached the silver, but did not adequately fix the silver halide.
The persulfate therefore appears to be unique as an oxidizing agent in a bleach-fix composition together with an alkylamino alkane thiol fixing agent such as 2,2-diethylaminoethane thiol.
Part C
The procedures described in Part B were repeated with bleach-fix solutions whose compositions are given below. The results are listed in Table III.
solution R K 2 S 2 O 8 50 g/l (0.25 mole) 1-Aminoethanethiol . HCl 37 g/l (0.25 mole) [H 2 NCH 2 CH 2 SH . HCl] H 2 O to 1 liter Solution S K 2 S 2 O 8 50 g/l (0.25 mole) Dimethylaminopropanethiol . HCl [(CH 3 ) 2 N--CH 2 CH 2 CH 2 SH . HCl] 41 g/l (0.25 mole) H 2 O to 1 liter Solution T K 2 S 2 O 8 50 g/l (0.25 mole) Diisopropylaminoethanethiol . HCl [(H 7 C 3 ) 2 N--CH 2 CH 2 SH . HCl] 64.5 g/l (0.25 mole) H 2 O to 1 liter Solution U K 2 S 2 O 8 50 g/l (0.25 mole) Cystamine . 2HCl [(SCH 2 Ch 2 NH 2 ) . 2HCl] 75 g/l (0.25 mole) H 2 O to 1 liter
TABLE III
Ag Ag/AgX IR Dens. Analysis Untreated Check 2.96 181 Samples treated in Solution R .15 182 Sample treated in Solution S .09 37 Sample treated in Solution T .81 59 Sample treated in Solution U .41 177
from this data it appears that solutions S and T effectively bleached and fixed the developed sample. Solutions R and U effectively bleached the silver, but did not adequately fix the silver halide.
Only alkylaminoalkyl thiol homologs of diethylaminoethane thiol appear to be operable fixing agents in a bleach-fix composition according to this invention.
From the above three evaluations it seems clear that aqueous bleach-fix solutions comprising a water-soluble persulfate and alkylaminoalkylthiols exhibit unique properties which are not duplicated in similar solutions containing either different oxidizing agents or fixing agents.
The following examples will serve to further demonstrate the effectiveness of the bleach-fixing solutions of the instant invention and the scope of the invention described herein.
EXAMPLE 1
A sample of Kodak Ektachrome MS Reversal Color Film, Type 2027, was sensitometrically exposed to a multicolor test object, MQ-developed, washed, reversal color developed, washed and bleach-fixed in a 1-liter aqueous solution containing 40 g potassium persulfate and 50 g diethylaminoethanethiol. The sample was completely bleach-fixed in 1.5 minutes at a temperature of 71°F.
EXAMPLE 2
The procedure described in Example 1 was successfully repeated with two similar bleach-fix solutions, wherein the potassium persulfate was replaced with equal molar quantities of sodium persulfate and ammonium persulfate, respectively.
EXAMPLE 3
When the fixing agent in the solution according to Example 1 was replaced with the two other known fixing agents sodium thiocyanate and thiourea, an inoperable bleach-fix was obtained because of the rapid oxidation of the thiocyanate and the thiourea by the persulfate.
The foregoing bleach-fix compositions can, of course, be utilized to treat any conventional silver or silver halide emulsion wherein it is sought to remove unwanted silver and/or silver halide and in conjunction with all of the conventional development, washing, stabilizing, etc., steps described in the discussion of the prior art set forth above. The use of these compositions in such processes is considered an integral part of this invention.
Concentrates of the bleach-fixing solutions described above may of course be prepared to reduce shipping costs incident to the shipping of the solvent (water) or even in dry powder form to increase the storage life only increasing the stability of such concentrates over long periods of time. When prepared as dry powder mixture or as concentrates the ultimate user simply dissolves the powder or concentrate in a suitable amount of water to provide the above-prescribed concentrations in the working bleach-fix solution. Such dry powder mixtures and/or concentrates which are brought to working solution concentration levels at the time of use are therefore to be included within the scope of this disclosure as well as the appended claims.
As should be clear from the foregoing discussion and examples, the alkylaminoalkylthiols of the solution of the present invention may be supplied in the form of acid salts of these materials, for example 2,2-diethylaminoethane thiol HCl, to permit greater ease of dissolution of these materials and increase their availability. When such salts are used, the dissociation products thereof (ie., HCl) will of course be present in the final "working" bleach-fix solution.
The invention has been described in detail with particular reference to preferred embodiments thereof; however, it should be understood that variations and modifications can be made within the spirit and scope of the invention and the same should not be limited except as set forth in the appended claims.