BACKGROUND OF THE INVENTION
1. Field of the Invention
[0001] The invention relates to a process of recycling spent photographic developer compositions
wherein the spent developer is collected and reconstituted and can be re-used without
detrimental effect on films processed therein.
2. Description of Related Art
[0002] Photographic developer compositions are well-known in the art. The development of
exposed silver halide photographic elements comprises a multiple step process of development,
fixing, washing and optionally a stopping step. The development step is conventionally
undertaken with an aqueous alkaline developer composition containing a developer,
also known as a developing agent either singly or with one or more additional developing
agents. A comprehensive list of developing agents is provided in C. E. K. Mees,
The Theory of the Photographic Process, Chapters 14-15, The Macmillan Company (1959, Rev. Ed.) The most commonly used developing
agent, particularly for processing black-and-white photographic silver halide elements
is hydroquinone. The hydroquinone or other suitable developing agent serves as a strong
silver reducing agent to reduce the silver halide grains containing a latent image
to yield the developed photographic image.
[0003] Hydroquinone-based developer compositions typically contain relatively high levels
of sulfite-based components. Also, the pH of hydroquinone-based developer compositions
is maintained within strict alkaline ranges with alkaline buffers, such as carbonates,
phosphates, borates, etc., either alone or in combination with hydroxides. While hydroquinone-based
developer compositions have been successfully employed for many years, recently the
use of these conventional developer compositions have been imposed with various guidelines
and regulations due to the toxicity and environmental hazards associated with the
hydroquinone, sulfite, and other components as well as the alkaline nature of the
developer.
[0004] Another class of developing agents are disclosed in U.S. Patent 2,688,549, which
teaches the use of ascorbic acid and sugar-type derivatives thereof as developing
agents in photographic developers. Because ascorbic acid and its derivatives are not
considered hazardous to the environment, it is desirable to have developer compositions
which use these developing agents. Similarly, U.S. Patent 5,098,819 teaches improved
photographic developer compositions which are free of hydroquinone and free of alkali
metal hydroxides and which utilize ascorbic acid, derivatives and salts thereof as
the developing agents.
[0005] Although these ascorbic acid-based developer compositions are more environmentally
friendly than hydroquinone-based developers, they nevertheless raise many of the same
serious environmental concerns as conventional developers when they are discharged
as waste. For example, developer compositions are highly alkaline with pH of at least
9.5, and they may also contain alkali sulfites as antioxidants in approximate amounts
from 10% to 100% of the amount of the developing agent. Further, effluents from spent
photographic developers have a Chemical Oxygen Demand (COD) of about 70,000 to 100,000
ppm, which exceeds the current limits set by the Environmental Protection Agency and
other regulatory agencies. The COD value represents the degree to which a solution
will compete with biological systems for the supply of oxygen. Although COD of the
developer effluent can be reduced by the addition of more chemicals to diminish the
reducing power of the effluent, this is a circuitous solution.
[0006] EP-A-0 498 968 discloses a photographic developing solution containing an ascorbic
acid derivative; the document also discloses that the ascortic acid derivative could
be recycled for a great part.
[0007] In view of the current environmental concerns surrounding the discharge of spent
photographic developer compositions into the environment and the likelihood of increased
environmental regulations, it is highly desirable to eliminate or reduce the introduction
of the spent developer effluent into the environment by recycling the used developer.
Apart from the obvious environmental benefits to recycling, there are also financial
advantages to recycling the spent developer due to a reduction in the amount of raw
materials needed and in the cost of compliance with environmental regulations.
[0008] A major obstacle to recycling, however, is being able to reconstitute the developer
such that the performance of photographic materials in recycled developer is equivalent
or substantially equivalent to the performance of the photographic materials in fresh
developer. Conventional hydroquinone-based developers are poor recycling prospects
because the oxidation products of hydroquinone (formed during development of photographic
materials) are developing agents themselves and thus contribute to the complexity
of the developer composition. The development activity of these oxidation products
makes it difficult, if not impossible, to reconstitute spent hydroquinone-type developer
compositions to obtain a developer composition having acceptable performance. In addition,
the degradation (i.e., oxidation) of hydroquinone produces large, dark (almost black
in color) polymeric compounds which are difficult to quantitatively analyze and separate.
The presence of these degradation products in developer compositions contributes to
sludge formation and staining of photographic elements processed therein.
[0009] The present invention is based upon the observation that ascorbic acid-type developing
agents produce light-colored oxidation products and the discovery that these products
do not affect the performance of the developer composition. It has also been discovered
that the presence of these products does not produce undesirable effects (such a staining)
to photographic elements processed therein.
SUMMARY OF THE INVENTION
[0010] In accordance with this invention, there is provided a process for recycling hydroquinone-free
black and white photographic developer compositions comprising the steps of:
(a) collecting spent developer, wherein the developer composition comprises a developing
agent selected from
(1) ascorbic acid and sugar type derivatives thereof,
(2) stereoisomers and diastereoisomers of ascorbic acid and their sugar-type derivatives,
(3) salts and mixtures of (1) and (2),
(4) 2-keto gluconic acid and derivatives thereof, and
(5) mixtures of (1) through (4); and
(b) reconstituting the spent developer for re-use, wherein the reconstituting step
includes at least one of (1) filtering the spent developer and (2) analyzing the spent
developer ; and thereafter (3) adding fresh ingredients to the developer and (4) diluting
the developer.
[0011] In another aspect, the present invention comprises a recycled black-and-white photographic
developer composition made according to the above process.
[0012] In a preferred embodiment, the hydroquinone-free black-and-white photographic developer
composition comprises:
Ingredients |
Amount (grams) |
sulfite ion |
3 to 30 |
sequestering agent |
1 to 7 |
bromide ion |
1.5 to 10.0 |
developing agent |
20 to 90 |
secondary developing agent |
0.25 to 3.0 |
antifoggants |
0.05 to 0.65 |
development accelerator |
0.01 to 3.0 |
Water |
to make 1 Liter |
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)
[0013] For the reasons noted above, the benefits of the present process are obtained when
the developer composition is free of hydroquinone-type developing agents. Non-hydroquinone
containing photographic developer compositions are disclosed, for example, in the
aforementioned U.S. Patents and in U.S. Patent Application Serial Nos. 07/683,248,
filed April 10, 1991 and 07/684,192, filed April 12, 1991. All of these references
disclose the use of ascorbic acid-type developing agents, which are preferred in the
present invention because they produce light-colored oxidation products which do not
interfere with development, and thus, can be successfully reused to provide an environmentally
sound method of developing photographic materials without detrimental effect on the
performance of the photographic materials.
[0014] It is contemplated that other developing agents suitable for use in developing black-and-white
photographic elements may be employed to advantage in the present invention. To be
a successful candidate for recycling, the developing agent must be one which avoids
the combination of disadvantages presented by hydroquinone-type developing agents.
In other words, it must be one which either (1) does not interfere with the developer
activity or produce undesirable effects on photographic elements processed therein;
or (2) is readily removed from the spent developer. Because of the complexity of developer
compositions used to process color films, they are not considered to be viable candidates
for recycling under the present process.
[0015] Developing agents which are employed in the present invention are selected from (1)
ascorbic acid and sugar-type derivatives thereof; (2) stereoisomers and diastereoisomers
of ascorbic acid, such as for example erythorbic acid, and their sugar-type derivatives;
(3) salts and mixtures of (1) and (2); (4) 2-keto gluconic acid and derivatives thereof,
and (5) mixtures of (1) through (4). Example of such compounds include, DL-ascorbic
acids, sorboascorbic acid, ω-lactoascorbic acid, maltoascorbic acid, L-araboascorbic
acid, sodium ascorbate, potassium ascorbate, sodium erythorbate and potassium erythorbate,
2-keto gluconates, potassium, sodium, ammonium, and methyl derivatives thereof. Most
preferred as the developing agents are ascorbic acid, sodium ascorbate, erythorbic
acid, and sodium erythorbate.
[0016] The developer composition may contain a multitude of conventional adjuvants which
serve various functions such as secondary developing agents, antifogging agents, buffers,
sequestering agents, swelling control agents, and development accelerators. Such adjuvants
are well known to those of ordinary skill in the art. Preferred secondary developing
agents are pyrazolidone or metol and derivatives thereof, with 4-hydroxymethyl-4-methyl-1-phenyl-3-pyrazolidone
and 1-phenyl-3-pyrazolidone being particularly preferred.
[0017] Examples of antifogging agents include benzotriazole, phenylmercaptotetrazole, and
benzimidazole and derivatives thereof, used alone or in admixture. Soluble bromides,
particularly alkali metal bromides (e.g., potassium bromide, sodium bromide) are the
preferred restrainers. It is preferred to have both antifoggant agents and a restrainer
in the developer. As discussed hereinbelow, it is particularly preferred for the developer
to contain from 7 to 10 grams/Liter of an alkali metal bromide, whereby a greater
percentage of spent developer can be recycled and reused in accordance with the present
process.
[0018] Small amounts of sequestering agents (or chelating agents) are also generally employed
to sequester trace metal ions, e.g., copper and iron ions, present in the water or
chemicals used to produce the developer composition and in the films. Preferred sequestering
agents are sodium salts of EDTA.
[0019] Preferably an antioxidant is also present in the developer composition. Antioxidants
are normally used in developer compositions as preservatives, however, such compounds
serve the additional function of an accelerating compound in the preferred developer
composition disclosed herein. Examples of suitable antioxidants include alkali metal
sulfites, bisulfites, metabisulfites and carbonyl-bisulfites adducts. A preferred
antioxidant is sodium bisulfite.
[0020] The pH of the developer is adjusted into the range of 9.0 to 11.0 by adding one or
more of an alkali metal carbonate, such as sodium or potassium carbonate; an alkali
metal bicarbonate, such as sodium or potassium bicarbonate; and, an alkali metal hydroxide.
Preferred are potassium hydroxide and potassium carbonate in a ratio of 2 to 1.
[0021] In addition to the above adjuvants, a development accelerator may be included in
the developer composition to increase developer activity to that of conventional development
times. Inclusion of a development accelerator in the ascorbic acid based developer
compositions discussed above renders such compositions equivalent or substantially
equivalent in development activity to conventional hydroquinone-based developers for
all families of films common to graphic arts, i.e., camera, contact, and photoelectronic
(e.g., scanner and imagesetting) films and papers. Developer accelerators suitable
for use in this invention include quaternary ammonium compounds and aryl hydrazides,
such as those disclosed in U.S. 4,937,160. Because many commercially available films
now contain hydrazine or hydrazide compounds as part of the film itself, the preferred
development accelerators are the quaternary ammonium compounds disclosed by Pangratz
in U.S. Serial Number 07/801,347. A particularly preferred quaternary ammonium development
accelerator is 1-phenethyl-2-picolinium bromide (PPB).
[0022] A suitable non-hydroquinone developer composition may comprise:
Ingredients |
Amount (grams) |
sulfite |
3 to 50 |
sequestering agent |
1 to 7 |
bromide |
1.5 to 10.0 |
developing agent |
20 to 90 |
secondary developing agent |
0.25 to 3.0 |
antifoggants |
0.05 to 0.65 |
development accelerator |
0.01 to 3.0 |
Water |
to make 1 Liter |
[0023] A typical and preferred developer composition will comprise:
|
Amount (grams) |
Ingredient |
Range |
Preferred |
Sulfite |
10 - 30 |
15.8 |
Tri-sodium EDTA |
2 - 7 |
3.5 |
Potassium bromide |
7 - 10 |
8 |
Sodium Erythorbate |
20 - 60 |
40 |
Glucono Delta Lactone |
0.1 - 1.0 |
0.7 |
4-hydroxymethyl-4-methyl-1-phenyl-3-pyrazolidone |
0.25 - 1 |
0.5 |
Benzotriazole |
0.15 - 0.35 |
0.25 |
Phenylmercaptotetrazole |
0.025 - 0.1 |
0.05 |
PPB |
0 - 0.5 |
0.3 |
Water |
to make 1 Liter |
[0024] The process of recycling spent photographic developer in accordance with the present
invention comprises the steps of collecting the spent developer and reconstituting
the spent developer for reuse as specified in claim 1. As noted, the first step in
the process is to collect spent developer. The term "spent developer" as used herein,
means a developer composition which has been used to process photographic film or
which otherwise has lost some of its development activity as compared to fresh or
virgin developer.
[0025] The collection step in the present process may conveniently be practiced by collecting
developer purged from a developer tank of a processor (such as during processing and/or
during automatic replenishment of the developer) in an off-line tank until a sufficient
quantity of spent developer is available for the next step. It is to be understood
that the process of the present invention does not require any particular amount of
spent developer be collected before the reconstituting step. However, for obvious
reasons, it is desirable for the present process to be practiced in batch quantities.
[0026] It is advantageous and indeed preferred for the collection step to include the separation
of liquid developer from any particulate matter present therein. It is not uncommon
for spent developer to contain a variety of foreign particulate matter, such as gelatin,
conglomerates of silver, hair, dirt, and paper clips. The separation of liquid developer
from particulate matter may be practiced in any conventional manner, such as by decanting
or filtration.
[0027] After a convenient quantity of spent developer has been collected, the next step
in the present process comprises reconstituting the developer for reuse. By "reconstitute",
it is meant that the concentration of the various components in the spent developer
is adjusted to obtain the concentration of such components as would be present in
fresh developer. The term "fresh developer" denotes a developer which is newly mixed,
and/or which has not been used to develop a significant amount of film, and/or which
has not been held at elevated development temperatures, i.e., 35°C to 43,3°C (95°F
to 110°F), for any extended period of time.
[0028] Depending upon the particular developer composition being recycled, the reconstituting
step may involve the addition of certain developer components to increase the concentration
thereof or the dilution of the spent developer to decrease the concentration of components.
More particularly, it is well known that many developer ingredients are wholly or
partially consumed during development of photographic elements. Thus, the concentration
of such ingredients in spent developer would be lower than the concentration in fresh
developer. In the reconstituting step, these ingredients would be added to the spent
developer.
[0029] On the other hand, it is equally well known that other developer ingredients, particularly
bromide ion, may actually be higher in concentration in spent developer than in fresh
developer. With bromide in particular, this increase is due to the use of the developer
to process films containing silver bromide grains. In such instances, the reconstituting
step would involve diluting the spent developer (e.g., with water) to reduce the concentration.
[0030] For most applications, both an addition and dilution will be necessary to reconstitute
the spent developer. In those circumstances, it may be convenient to combine the addition
and dilution steps as may be required by formulating a fresh developer composition
which does not contain the particular ingredients which need to be diluted (such as,
for example, a bromide-free developer) and adding that composition to the spent developer.
In any event, the result of the reconstituting step should be a developer composition
that is substantially the same as a fresh developer composition. In the case of ascorbic
acid-type developers, the reconstituted developer composition would also contain the
oxidation products of the ascorbic acid-type developing agents.
[0031] It is particularly preferred for an analysis step to be performed prior to or as
part of the reconstituting step. The analysis step, as the name implies, would comprise
an analysis of the spent developer to determine the concentration of the various ingredients
which are to be reconstituted and the pH. Conventional analytical methods, such as
titration, spectroscopy and chromatography, may be used to conduct the analysis of
the spent developer. In particular, the spent developer should be analyzed for the
concentration of developing agent (both primary and secondary) and antifoggant(s),
since these components are usually critical to the performance of a developer.
[0032] Based on conventional replenishment rates for developer, it is typically the case
that all of the developer components (with the exception of bromide ion) are present
in the spent developer from 80% to 90% of their original starting concentrations.
The components which are lower in concentration than the original starting concentration
of the fresh developer are added to the spent developer in an amount sufficient to
achieve original starting concentrations based on the final volume of reconstituted
developer.
[0033] It may also be necessary to reconstitute other components in the spent developer,
such as for example, sequestering agents, swelling control agents, and antioxidants,
as these components are often necessary for suitable performance of the reconstituted
developer. Many of these other components, however, can be reconstituted on a volumetric
basis.
[0034] As already noted, it may be necessary to dilute the spent developer in order to compensate
for the higher concentration of the bromide ion or to compensate for the evaporation
losses in the developer due to high temperature processing. It is important to maintain
the concentration of the bromide ion due to its restraining effect; the greater the
bromide ion concentration, the more the development of film is restrained. The concentration
of the bromide ion in the spent developer solution is generally dependent upon the
mix of films processed in the developer, i.e., the proportion of the processed films
which are totally or partially silver bromide grain films. It should be understood
that if all the films processed in the developer are entirely silver chloride grain
films, then the spent developer may not need to be diluted to the extent that the
spent developer would if some of the films processed contained silver bromide. Another
factor which may influence the concentration of bromide ion in the spent developer
includes the amount of developed density, i.e., the proportion of the imaged film
which is high density and low density.
[0035] A typical non-hydroquinone developer composition for black-and-white films will contain
from 2 to 3 g/L of bromide ion, which can increase to 8 to 10 g/L in spent developer.
Thus, in reconstituting such developers, it may be necessary to dilute the spent developer
from 70% to 30% of the collected volume to reduce the bromide ion concentration to
acceptable levels. In other words, using conventional developer compositions to process
silver bromide films, the recycled developer resulting from the present process would
comprise between 30-70% spent developer and 70-30% fresh ingredients.
[0036] It has been found that the efficiency of the present process is improved substantially
by using a developer composition having a bromide concentration of 7-10 g/L. Ascorbic
acid-type developer compositions in particular are able to tolerate such high levels
of bromide. With a high bromide starting level, the additional bromide resulting from
film through-put represents a much lower percentage increase in bromide as compared
to the more conventional developer compositions. Thus, a lower dilution factor is
needed to return the elevated bromide levels to an acceptable starting concentration.
In fact, using the preferred developer composition in the present process results
in recycled developer comprising from about 70% to greater than 97% spent developer
and only up to about 30% fresh ingredients.
[0037] After the spent developer has been analyzed and the appropriate additions and dilutions
have been effected, the pH of the developer should be adjusted using one or more of
the well known adjuvants for that purpose. Preferably, the pH should be between 9.0
and 11.0.
[0038] It will be readily apparent to those of ordinary skill that the composition of the
recycled developer will not (and need not) be identical to the composition of fresh
developer. Indeed, as noted previously, ascorbic acid-type developing agents degrade
to light-colored oxidation products. The presence of these products does not interfere
with the activity of the recycled developer and they do not adversely affect photographic
elements processed therein. Therefore, these oxidation products need not be removed
from the recycled developer. Similarly, ingredients such as carbonates and hydroxides,
which serve only as pH adjusting and buffering agents, may be substituted with equivalent
alkali buffering and adjusting agents in the reconstituting step, so long as the recycled
developer has the proper pH and buffer capacity.
[0039] Accordingly, it is to be understood that during the reconstituting step of the process
of the present invention, it is only necessary for those ingredients essential for
the proper functioning of the developer to be adjusted to within their acceptable
range for fresh developer.
[0040] Photographic developers that have been recycled according to the present process
can be used in the same manner as fresh developer solutions, including as a replenishment
solution and to initially charge the processor. They may be used in a variety of processing
equipment and techniques well known to those skilled in the art.
EXAMPLES
Example 1A
[0041] The following is an example of a preferred developer composition prepared and recycled
according to the teachings of the present invention. A fresh developer composition
was made having the composition as shown in Table A.
TABLE A
Ingredient |
Grams/Liter working strength |
Tri-sodium ethylene-diaminotetraacetic acid (EDTA) |
2 |
Sodium bisulfite |
10 |
Potassium bromide |
3 |
Erythorbic acid |
80 |
4-hydroxymethyl-4-methyl-1-phenyl-3-pyrazolidone |
0.5 |
Benzotriazole |
0.5 |
Phenylmercaptotetrazole(PMT) |
0.1 |
Water |
to 1 Liter |
[0042] The pH of the solution was adjusted to 10.5 using a hydroxide and carbonate buffer
solution, (approximately a 2:1 ratio hydroxide:carbonate). The developer solution
was placed into the developer tank of a deep tank processor and maintained at 37,8°C
(100°F).
[0043] Approximately 23,226 m
2 (250 sq. feet) of various types of black-and-white graphic arts films (E. I. du Pont
de Nemours & Co., Wilmington, DE) were developed in the processor per week. Films
were sensitometrically tested when the processor was initially charged with the fresh
developer. The various films were processed in the developer with a 23 second development
time. The developer in the tank was replenished with fresh developer solution having
the above composition at a rate of 0,0388 ml/cm
2 (0.25 ml/sq.in.) of film processed. Spent developer (developer which was purged from
the development tank during processing of the films and/or during replenishment) was
collected in an off-line tank until 37,85 l (10 gallons) had been collected (approximately
2-4 weeks processing time). The spent developer was filtered with a 10 µm particle
size filter to remove particulate matter therefrom.
[0044] A sample of the spent developer was analyzed to determine the concentration of potassium
bromide, erythorbic acid, Dimezone-S®, PMT, and benzotriazole. The concentration of
bromide ion was determined using titration. The concentration of erythorbic acid was
determined using UV spectroscopy. The concentrations of PMT, Dimezone-S and benzotriazole
were determined using high performance liquid chromatography (HPLC). Results of the
analysis are shown in Table B.
[0045] Based upon the bromide concentration, 21,198 l (5.6 gallons) of the spent developer
was removed from the off-line tank. To the remaining 16,656 l (4.4 gallons) of spent
developer, the ingredients were added in the amounts indicated in Table B and enough
water was added to bring the total volume up to 37,85 l (10 gallons). The pH was adjusted
to 10.5 with hydroxide/carbonate buffer solution. The recycled developer was added
as a replenishment solution to the developer tank in the processor. The cycle of processing
23,226 m
2 (250 sq ft) of film per week; collecting spent developer; reconstituting; and reusing
the developer was repeated 10 times.
TABLE B
Ingredient |
Concentration in Spent Developer |
Amount Added to 16,656 l (4.4 gal) of Spent Developer |
Potassium bromide |
6.8 g/Liter |
-- |
Erythortic Acid |
96% of original level (76.8 g/L) |
1746 g |
PMT |
67.9% of original level (0.0679 g/L) |
2.65 g |
4-hydroxymethyl-4-methyl-1-phenyl-3-pyrazolidone |
91.7% of the original level (0.4585 g/L) |
11.27 g |
Benzotriazole |
93% of the original level (0.4650 g/l) |
11.17 g |
[0046] After 10 cycles, the sensitometric performance of films developed in the recycled
developer was compared against the sensitometric performance of films processed in
fresh developer. A conventional, fresh hydroquinone-containing developer (CUFD®; E.
I. du Pont de Nemours & Co.) was also included for comparison. Speed, gradient and
maximum density (Dmax) were determined for all films and papers in each of the three
developers. Results are reported in Table C. Speed and gradient in the reconstituted
developer and CUFD are reported as a percentage, using the films developed in fresh
developer as the standard.
TABLE C
FILM |
EXPOSURE |
DEVELOPER |
1RELATIVE SPEED |
2RELATIVE GRAD |
Dmax |
CPR (positive |
Point source |
FRESH |
100 |
100 |
4.3 |
camera speed) |
43, 056 Lumens/m2 (4 ft. candles), |
RECYCLED |
122.5 |
100 |
4.2 |
4 sec |
CUFD |
100 |
106 |
4.5 |
|
ONF (negative |
Point source |
FRESH |
100 |
100 |
5.0 |
camera speed) |
2,153 Lumens/m2 (0.2 ft. |
RECYCLED |
95.5 |
105.8 |
5.0 |
candles), 12 sec |
CUFD |
103 |
112 |
5.3 |
|
BLD (bright |
Xenon flash |
FRESH |
100 |
100 |
5.8 |
light |
15 sec |
RECYCLED |
100 |
102.6 |
5.6 |
positive) |
|
CUFD |
100 |
110.5 |
5.7 |
BLF (bright |
Xenon flash |
FRESH |
100 |
100 |
5.6 |
light |
15 sec |
RECYCLED |
98.8 |
92.9 |
5.2 |
negative) |
|
CUFD |
98.8 |
96 |
5.6 |
CHC (image-setting film) |
*10-3 sec, with 5 color |
FRESH |
100 |
100 |
5.1 |
correction and 0.7 neutral |
RECYCLED |
113 |
100 |
5.4 |
density filters |
CUFD |
89 |
96 |
5.8 |
|
CHC-P (paper) |
*10-3 sec, with 5 color |
FRESH |
100 |
100 |
1.6 |
correction and 0.7 neutral |
RECYCLED |
85 |
90.9 |
1.7 |
density filters |
CUFD |
100 |
100 |
1.8 |
* Exposure on an EG&G Sensitometer, Model PH-11 (Grier Inc.) using a square root of
2 wedge. |
1 Speed was measured at 0.25 density for all films and papers. |
2 Gradient was measured at 0.30 to 0.05 densities for positive films and papers, and
at 1.5 to 0.3 densities for the negative films and papers. |
Example 1B
[0047] Example 1 was repeated with the exception that bromide-free developer was used instead
of water in the reconstitution step. The amounts of developer ingredients and bromide-free
developer are indicated in Table D. Sensitometric activity was as reported in Table
C, above.
TABLE D
Ingredient |
Concentration in Spent Developer |
Amount Added to (4.4 gal) 16,656 l of Spent Developer |
Potassium bromide |
6.8 g/Liter |
-- |
Erythorbic Acid |
96% of original level (76.8 g/L) |
3.7 g |
PMT |
67.9% of original level (0.0679 g/L) |
0.032 g |
4-hydroxymethyl-4-methyl-1-phenyl-3-pyrazolidone |
91.7% of the original level (0.4585 g/L) |
0.042 g |
Benzotriazole |
93% of the original level (0.4650 g/l) |
0.035 g |
Bromide-free developer |
|
to make (10 gallons) 37,85 l |
Example 2
[0048] The following example demonstrates the improved efficiency of the present process
using the preferred developer composition.
[0049] A fresh developer composition was made as shown in Table E.
TABLE E
Ingredient |
Gram/liter working strength |
Tri-sodium ethylene-diaminotetraacetic acid (EDTA) |
3.5 |
Sodium bisulfite |
22 |
Potassium bromide |
8 |
Erythorbic acid |
40 |
4-hydroxymethyl-4-methyl-1-phenyl-3-pyrazolidone |
0.5 |
Benzotriazole |
0.25 |
Phenylmercaptotetrazole(PMT) |
0.05 |
Phenylethyl picolinium bromide (PPB) Water to 1 Liter |
0.3 |
[0050] The pH of the solution was adjusted to 10.7 using a 2:1 hydroxide:carbonate buffer
solution. The developer solution was placed into the developer tank of a deep tank
processor and maintained at 37,8°C (100°F). Various black-and-white graphic arts films
were processed and sensitometrically tested, and spent developer collected as in Example
1A.
[0051] After 34,07 l (9 gallons) of spent developer were collected in the off-line tank,
the spent developer was filtered with a 10 µm particle size filter and a sample of
the spent developer was analyzed to determine the concentration of potassium bromide,
erythorbic acid, Dimezone-S, PMT, benzotriazole, and PPB as in Example 1A. The concentration
of PPB was determined using HPLC. Results of the analysis are reported in Table F.
[0052] Based upon the bromide concentration, 3,79 l (1 gallon) of spent developer was removed
from the off-line tank. To the remaining 30,28 l (8 gallons) of spent developer, ingredients
were added in the amounts indicated in Table F and enough water was added to make
37,85 l (10 gallons) and the pH was adjusted to 10.7. The recycled developer was added
as a replenishment solution to the developer tank in the processor.
TABLE F
Ingredient |
Concentration in Spent Developer |
Amount Added to 30,28 l (8 gal) of Spent Developer |
Potassium bromide |
9.38 g/liter |
-- |
Erythorbic Acid |
100% of original level (40 g/l) |
301.6 g |
PMT |
96.9% of original level (0.048 g/l) |
0.44 g |
4-hydroxymethyl-4-methyl-1-phenyl-3-pyrazolidone |
100% of the original level (0.5 g/l) |
3.77 g |
Benzotriazole |
100% of the original level (0.25 g/l) |
1.88 g |
PPB |
80.9% of the original level (0.24 g/l) |
4.07 g |
[0053] The cycle of processing, collection, reconstituting and reuse was repeated 10 times
and the sensitometric performance of films processed in recycled developer was compared
to that of films processed in fresh developer, all as in Example 1A. Results are reported
in Table G.
TABLE G
FILM |
EXPOSURE |
DEVELOPER |
1RELATIVE SPEED |
2RELATIVE GRAD |
Dmax |
CPR (positive |
Point source |
FRESH |
100 |
100 |
4.3 |
camera speed) |
43,056 Lumens/m2 (4 ft. candles), |
RECYCLED |
97.6 |
104 |
4.3 |
4 sec |
CUFD |
95.2 |
106 |
4.5 |
|
ONF (negative |
Point source |
FRESH |
100 |
100 |
4.9 |
camera speed) |
2,153 Lumens/m2 (0.2 ft. |
RECYCLED |
92.8 |
98 |
5.2 |
|
candles), 12 sec |
CUFD |
98.6 |
116 |
5.3 |
BLD (bright |
Xenon flash |
FRESH |
100 |
100 |
5.6 |
light |
15 sec |
RECYCLED |
109.5 |
95 |
5.4 |
positive) |
|
CUFD |
95.2 |
105 |
5.7 |
BLF (bright |
Xenon flash |
FRESH |
100 |
100 |
5.3 |
light |
15 sec |
RECYCLED |
102.5 |
94 |
5.4 |
negative) |
|
CUFD |
102.5 |
100 |
5.6 |
CHC (image-setting film) |
*10-3 sec, with 5 color |
FRESH |
100 |
100 |
5.3 |
correction and |
RECYCLED |
108.8 |
96.3 |
5.5 |
0.7 neutral density filters |
CUFD |
90.3 |
92.6 |
5.8 |
|
CHC-P (paper) |
*10-3 sec, with 5 color |
FRESH |
100 |
100 |
1.6 |
correction and |
RECYCLED |
100 |
90.9 |
1.7 |
0.7 neutral density filters |
CUFD |
79 |
100 |
1.8 |
1. A process for recycling hydroquinone-free black and white photographic developer compositions
comprising the steps of:
(a) collecting spent developer, wherein the developer composition comprises a developing
agent selected from
(1) ascorbic acid and sugar type derivatives thereof,
(2) stereoisomers and diastereoisomers of ascorbic acid and their sugar-type derivatives,
(3) salts and mixtures of (1) and (2),
(4) 2-keto gluconic acid and derivatives thereof, and
(5) mixtures of (1) through (4); and
(b) reconstituting the spent developer for re-use, wherein the reconstituting step
includes at least one of (1) filtering the spent developer and (2) analyzing the spent
developer ; and thereafter (3) adding fresh ingredients to the developer and (4) diluting
the developer.
2. The process of claim 1, wherein the fresh ingredients comprise developing agent, secondary
developing agent, and antifogging agent.
3. The process of claim 2, wherein the antifogging agent is selected from benzotriazole;
phenylmercaptotetrazole; and benzimidazole and derivatives thereof.
4. The process of claim 2, wherein the secondary developing agent is selected from pyrazolidones
and derivatives thereof; and metol and derivatives thereof.
5. The process of claim 1, wherein the photographic developer composition comprises 7
to 10 g/l of an alkali metal bromide.
6. The process of claim 1, wherein the photographic developer composition comprises
Ingredient |
Amount (g) |
sulfite |
3 to 50 |
sequestering agent |
1 to 7 |
bromide |
1.5 to 10.0 |
developing agent |
20 to 90 |
secondary developing agent |
0.25 to 3.0 |
antifoggants |
0.05 to 0.65 |
development accelerator |
0.01 to 3.0 |
water |
to make 1 l. |
7. The process of claim 1, wherein the photographic developer composition comprises:
Ingredient |
Amount (g) |
sulfite ion |
15.8 |
tri-sodium ethylenediamino-tetraacetic acid |
3.5 |
potassium bromide |
8 |
sodium erythorbate |
40 |
glucono delta lactone |
0.7 |
4-hydroxymethyl-4-methyl-1-phenyl-3-pyrazolidone |
0.5 |
benzotriazole |
0.25 |
phenylmercaptotetrazole |
0.05 |
phenylethyl picolinium bromide |
0.3 |
water |
to make 1 l. |
8. A recycled black-and-white photographic developer composition made according to the
process of claim 1.
9. The recycled developer composition of claim 8, comprising at least 30 % (by volume)
of recycled material.
10. The recycled developer composition of claim 9, comprising 7 to 10 g/l of an alkali
metal bromide.
11. The recycled photographic developer composition of claim 8, comprising
Ingredient |
Amount (g) |
sulfite |
3 to 50 |
sequestering agent |
1 to 7 |
bromide |
1.5 to 10.0 |
developing agent |
20 to 90 |
secondary developing agent |
0.25 to 3.0 |
antifoggants |
0.05 to 0.65 |
development accelerator |
0.01 to 3.0 |
water |
to make 1 l. |
12. The recycled photographic developer composition of claim 8, comprising
Ingredient |
Amount (g) |
sulfite ion |
15.8 |
tri-sodium ethylenediamino-tetraacetic acid |
3.5 |
potassium bromide |
8 |
sodium erythorbate |
40 |
glucono delta lactone |
0.7 |
4-hydroxymethyl-4-methyl-1- phenyl-3-pyrazolidone |
0.5 |
benzotriazole |
0.25 |
phenylmercaptotetrazole |
0.05 |
phenylethyl picolinium bromide |
0.3 |
water |
to make 1 l. |
1. Ein Verfahren zur Rückführung von hydrochinonfreien fotografischen Schwarzweiß-Entwicklerzusammensetzungen,
das die folgenden Stufen umfaßt :
(a) das Sammeln von verbrauchtem Entwickler, wobei die Entwicklerzusammensetzung eine
Entwicklersubstanz aus der folgenden Gruppe enthält :
(1) Ascorbinsäure und Ascorbinsäure-Zuckerderivate,
(2) Stereoisomere und Diastereoisomere von Ascorbinsäure und Ascorbinsäure-Zuckerderivate,
(3) Salze und Mischungen aus (1) und (2),
(4) 2-Ketogluconsäure und deren Derivate, und
(5) Mischungen aus (1) bis (4), und
(b) die Rekonstituierung des verbrauchten Entwicklers zwecks seiner Wiederverwertung,
wobei zur Rekonstituierung (1) der verbrauchte Entwickler filtriert und/oder (2) der
verbrauchte Entwickler analysiert wird, und anschließend (3) frische Ingredienzien
zum Entwickler gegeben werden und (4) der Entwickler verdünnt wird.
2. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß die frischen Ingredienzien
Entwicklersubstanz, Hilfsentwickler-substanz und Schleierschutzmittel umfassen.
3. Verfahren nach Anspruch 2, dadurch gekennzeichnet, daß das Schleierschutzmittel Benztriazol,
Phenylmercaptotetrazol, Benzimidazol oder ein Derivat derselben ist.
4. Verfahren nach Anspruch 2, dadurch gekennzeichnet, daß die Hilfsentwicklersubstanz
Pyrazolidon, Metol oder ein Derivat derselben ist.
5. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß die fotografische Entwicklerzusammensetzung
zwischen 7 und 10 g/l eines Alkalimetallbromids enthält.
6. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß die fotografische Entwicklerzusammensetzung
folgende Ingredienzien enthält :
Ingrediens |
Menge (g) |
Sulfit |
3 bis 50 |
Komplexbildner |
1 bis 7 |
Bromid |
1,5 bis 10,0 |
Entwicklersubstanz |
20 bis 90 |
Hilfsentwickler |
0,25 bis 3,0 |
Antischleiermittel |
0,05 bis 0,65 |
Entwicklungsbeschleuniger |
0,01 bis 3,0 |
Wasser zum Auffüllen auf |
1 Liter |
7. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß die fotografische Entwicklerzusammensetzung
folgende Ingredienzien enthält :
Ingrediens |
Menge (g) |
Sulfition |
15,8 |
Trinatriumethylendiamin-tetraessigsäure |
3,5 |
Kaliumbromid |
8 |
Natriumerythroascorbat |
40 |
Glucono-δ-lacton |
0,7 |
4-Hydroxymethyl-4-methyl-1-phenyl-3-pyrazolidon |
0,5 |
Benztriazol |
0,25 |
Phenylmercaptotetrazol |
0,05 |
Phenylethylpicoliniumbromid |
0,3 |
Wasser zum Auffüllen auf |
1 Liter |
8. Eine wiederverwertbar gemachte fotografische Schwarzweiß-Entwicklerzusammensetzung,
die nach dem in Anspruch 1 beschriebenen Verfahren hergestellt ist.
9. Die wiederverwertbar gemachte Entwicklerzusammensetzung von Anspruch 8, die wenigstens
30% (Volumen-%) wiederverwertbar gemachtes Material enthält.
10. Die wiederverwertbar gemachte Entwicklerzusammensetzung von Anspruch 9, die wenigstens
7 bis 10 g/l eines Alkalimetallbromids enthält.
11. Die wiederverwertbar gemachte fotografische Entwicklerzusammensetzung von Anspruch
8, die folgende Ingredienzien enthält :
Ingrediens |
Menge (g) |
Sulfit |
3 bis 50 |
Komplexbildner |
1 bis 7 |
Bromid |
1,5 bis 10,0 |
Entwicklersubstanz |
20 bis 90 |
Hilfsentwickler |
0,25 bis 3,0 |
Antischleiermittel |
0,05 bis 0,65 |
Entwicklungsbeschleuniger |
0,01 bis 3,0 |
Wasser zum Auffüllen auf |
1 Liter |
12. Die wiederverwertbar gemachte fotografische Entwicklerzusammensetzung von Anspruch
8, die folgende Ingredienzien enthält :
Ingrediens |
Menge (g) |
Sulfition |
15,8 |
Trinatriumethylendiamintetraessigsäure |
3,5 |
Kaliumbromid |
8 |
Natriumerythroascorbat |
40 |
Glucono-δ-lacton |
0,7 |
4-Hydroxymethyl-4-methyl-1-phenyl-3-pyrazolidon |
0,5 |
Benztriazol |
0,25 |
Phenylmercaptotetrazol |
0,05 |
Phenylethylpicoliniumbromid |
0,3 |
Wasser zum Auffüllen auf |
1 Liter |
1. Procédé pour le recyclage de compositions de révélateur photographique blanc et noir
exempt d'hydroquinone comprenant les étapes consistant à :
(a) recueillir le révélateur usagé, caractérisé en ce que la composition de révélateur
comprend un développateur choisi parmi
(1) l'acide ascorbique et ses dérivés du type des sucres,
(2) les stéréo-isomères et les diastéréo-isomères de l'acide ascorbique et leurs dérivés
du type des sucres,
(3) les sels et mélanges de (1) et (2),
(4) l'acide 2-cétogluconique et ses dérives, et
(5) les mélanges des substances (1) à (4)
(b) reconstituer le révélateur usagé pour sa réutilisation, caractérisé en ce que
l'étape de reconstitution consiste à (1) filtrer le révélateur usagé et/ou à (2) analyser
le révélateur usagé; et/ou ensuite à (3) ajouter des ingrédients neufs au révélateur
et/ou à (4) diluer le révélateur.
2. Procédé selon la revendication 1, caractérisé en ce que les ingrédients neufs comprennent
un développateur, un développateur auxiliaire et un inhibiteur de voile.
3. Procédé selon la revendication 2, caractérisé en ce que l'inhibiteur de voile est
choisi parmi le benzotriazole, le phénylmercaptotétrazole, et le benzimidazole et
ses dérivés.
4. Procédé selon la revendication 2, caractérisé en ce que le développateur auxiliaire
est choisi parmi les pyrazolidones et leurs dérivés, et le métol et ses dérivés.
5. Procédé selon la revendication 1, caractérisé en ce que la composition de révélateur
photographique contient 7 à 10 g/l d'un bromure des métaux alcalins.
6. Procédé selon la revendication 1, caractérisé en ce que la composition de révélateur
photographique comprend
ingrédient |
quantité (en g) |
sulfite |
3 à 50 g |
complexant |
1 à 7 |
bromure |
1,5 à 10,0 |
développateur |
20 à 90 |
développateur auxiliaire |
0,25 à 3,0 |
inhibiteurs de voile |
0,05 à 0,65 |
accélérateur de développement |
0,01 à 3,0 |
eau pour compléter jusqu'à 1 ℓ. |
|
7. Procédé selon la revendication 1, caractérisé en ce que la composition de révélateur
photographique comprend
ingrédient |
quantité (en g) |
ion sulfite |
3 à 50 g |
acide éthylènediaminetétraacétique de trisodium |
3,5 |
bromure de potassium |
8 |
érythroascorbate de sodium |
40 |
glucono-δ-lactone |
0,7 |
4-hydroxyméthyl-4-méthyl-1-phényl-3-pyrazolidone |
0,5 |
benzotriazole |
0,25 |
phénylmercaptotétrazole |
0,05 |
bromure de phényléthylpicolinium |
0,3 |
eau pour compléter jusqu'à 1 ℓ. |
|
8. Composition de révélateur photographique blanc et noir recyclée réalisée conformément
au procédé de la revendication 1.
9. La composition de révélateur recyclée de la revendication 8, comprenant au moins 30%
(en volume) de matière recyclée.
10. La composition de révélateur recyclée de la revendication 9, comprenant 7 à 10 g/l
d'un bromure des métaux alcalins.
11. La composition de révélateur photographique recyclée de la revendication 8, comprenant
ingrédient |
quantité (en g) |
sulfite |
3 à 50 g |
complexant |
1 à 7 |
bromure |
1,5 à 10,0 |
développateur |
20 à 90 |
développateur auxiliaire |
0,25 à 3,0 |
inhibiteurs de voile |
0,05 à 0,65 |
accélérateur de développement |
0,01 à 3,0 |
eau pour compléter jusqu'à 1 ℓ. |
|
12. La composition de révélateur photographique recyclée de la revendication 8, comprenant
ingrédient |
quantité (en g) |
ion sulfite |
3 à 50 g |
acide éthylènediaminetétraacétique de trisodium |
3,5 |
bromure de potassium |
8 |
érythroascorbate de sodium |
40 |
glucono-δ-lactone |
0,7 |
4-hydroxyméthyl-4-méthyl-1-phényl-3-pyrazolidone |
0,5 |
benzotriazole |
0,25 |
phénylmercaptotétrazole |
0,05 |
bromure de phényléthylpicolinium |
0,3 |
eau pour compléter jusqu'à 1 ℓ. |
|