WO2004086139A1

WO2004086139A1 - Photographic processing solutions

Info

Publication number: WO2004086139A1
Application number: PCT/GB2004/001043
Authority: WO
Inventors: John Richard Fyson; Peter Hewitson
Original assignee: Eastman Kodak Company
Priority date: 2003-03-27
Filing date: 2004-03-11
Publication date: 2004-10-07
Also published as: GB0307046D0

Abstract

A method of photographic processing in which the cleaning solution used for washing the processor comprises at least a constituent part of the processing solution.

Description

HOTOGRAPHIC PROCESSING SOLUTIONS

Field of the Invention

This invention relates to the field of processing, in particular to the solutions used in a photographic process.

Background of the Invention

To prevent the working characteristics of a bath of photographic developer from changing during the development of a quantity of exposed silver halide photographic material, and also to maintain the volume of the developer, it is common practice to add a replenisher. Such a replenisher is usually a more concentrated aqueous solution of the principal developer constituents that are consumed during development. The replenisher has a reduced concentration of components released during development so that these compounds are diluted. In this way the developer tank solution can be maintained at a constant composition. If the replenisher were to be used in the processor when the process was first started it would be too active, i.e. it would have a higher concentration of consumed products compared to the equilibrium position and low concentrations of released products. In order to get around this problem a specially formulated 'tank' solution can be used which has the same activity and approximately the same constitution as the equilibrium constitution of the developer tanks. This 'tank' solution can usually be made by diluting the replenisher and adding a starter. In this way the developer replenisher has the same activity and similar constitution as the final equilibrium 'tank' developer. The starter is often a mixture of acid, usually acetic acid or a bicarbonate, and alkali metal halides. The volume of halides added is determined by experiment or calculation. US 3276874 suggests using hydrobromic acid as a starter solution as this has less components and does not introduce an alkali metal ion. If the process is started automatically with a fresh solution the tank solution has to be made and a starter has to be supplied to the processor. This could be done manually in a processor that is only started from fresh occasionally such as in a minilab. However some low volume and single use processors must be started from fresh frequently. This is done most conveniently and reliably by carrying out this action automatically. In this case, if the processing is done with replenisher, an additional tank of starter has to be supplied. This involves more equipment, required to meter, pump and detect empty tanks etc. Single use processors need washing between each process to remove the chemistry of the last step of the process. Low volume processors, such as the one described in PCT GB 2002/004141 are designed to process a length of material and then be washed out when no further processing is envisaged, for example after a certain delay in between orders. The washing of the processor ensures that no chemistry is left in the processor that might affect the next process cycle. It also removes any potential for the crystallisation of deposits on the processor parts. Usually water is used to carry out this washing or cleaning.

The wash, or cleaning, solution has to be supplied to the processor, either directly from a convenient water supply should it be available or from an additional tank in the processor . The latter takes up valuable space in the processor and requires some associated ancillary equipment such as pumps and level detectors to pump the solution into the machine. The volume of this extra tank can be minimised by using counter current machine washing, as described in EP 03003321.1, but still has to form part of the processing apparatus.

Problem to be solved by the Invention

The invention aims to provide a method of processing which reduces the number of supply tanks and ancillary equipment required. The invention further aims to provide a cleaning solution which leaves no solid residue in the processor.

Summary of the Invention

According to the present invention there is provided a method of processing in which the cleaning solution for washing the processor comprises at least a constituent part of the processing solution. In a preferred embodiment the same solution is used for the cleaning solution and as the starter solution. This solution is ideally substantially volatile at processing temperatures such that after cleaning it leaves no residue in the processor.

Advantageous Effect of the Invention The method of the invention reduces the number of supply tanks required for the apparatus. The cleaning solution leaves no solid residue in the apparatus.

In a preferred embodiment the same solution is used as the cleaning solution and as the starter solution. The starter solution is then used to convert the replenisher solution into a tank solution so that the process can be run such that there is little or no change in the sensitometry of the processed material.

Brief Description of the Drawings

The invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a graph showing the density of a control strip;

Figure 2 is a graph showing the density for a strip processed in accordance with the invention;

Figure 3 is a second graph showing the density of a control strip; and Figure 4 is a second graph showing the density for a strip in accordance with the invention.

Detailed Description of the Invention

In the method according to the invention the solution used to clean the processor is the same solution as the solution used to process the photographic material. Alternatively, the cleaning solution is only a constituent part of the processing solution.

In a particular embodiment the cleaning solution is the same solution as is used as the starter solution, added to the developer solution at the start of the processing run. This starter solution is only added at the beginning of a processing run. In the case of single use processors this will occur far more frequently than in large processors such as minilabs. The starter solution should ideally be substantially volatile at processing temperature such that after cleaning it leaves no residue. These solutions should provide acid and halides to be able to reduce the reactivity of the developer replenisher to that of a seasoned solution, i.e. tank solution, when this solution is used as a starter. This solution could comprise one or more one hydrohalic acid chosen from hydrochloric, hydrobromic and hydroiodic acid. Alternatively the solution might consist of a volatile organic acid such as acetic acid and a volatile halide for example ammonium chloride.

Example 1

The experiment was carried out in a shallow tray processor as described in PCT GB2002/004141. It was built with a 4 inch (.10.2cm) tray width with two consecutive trays - one for developer and one for bleach fix. Washing after the bleach was by means of an inclined plane ramp, as described in GB 0220263.8. Each tray was fitted with a replenishment pump and a drain pump. Each tray could be charged by turning on the replenisher pump only. During the processing operation the level in the tank was kept constant by adjusting the drain pump to keep the amount of liquid in the tray constant.

The following solutions were used

Developer Replenisher

To make one litre

875g water (demineralised)

33g potassium carbonate

5g DEHA

7.5g CD3 (used part b of a kit as had run out ) lOdrops Tween 80

1ml Dequest 2010

2g Blankophor REU pH adjusted with 10% nitric acid to 10.5 Starter/Processor Cleaning solution

0.10 mole/litre hydrochloric acid to which was added 2g/l Tween 80

Bleach-fix

To make 1 litre

200 ml 1.56M ferric ammonium EDTA solution 140g ammonium thiosulphate

20g sodium metabisulphite lOg glacial acetic acid pH adjusted to 6.0 with either ammonia solution or sulphuric acid

Paper Wash

Tap water to which was added 2g/l Silwet L-7607.

Long lengths of Ektacolor Edge 8™ glossy surface colour print paper were exposed in a constant exposure sensitometer to give an even constant density of about 0.8 in all layers.. This was cut into lengths approximately 105cm long and processed using the baths of formulae outlined above and in the 4 inch shallow tray processor with settings to give the following process.

Before processing the process the processor was cleaned with either four 20ml changes of water(the control comparison) in the counter-current mode discussed in EP 03003321.1 or four 20ml changes of a starter/processor cleaning solution according to the invention, also delivered in the same counter-current mode. The trays were drained of liquid and allowed to dry. No crystals were seen in the trays with either solution. To start the process either 8mls water (the control comparison) or a starter/processor cleaning solution in accordance with the invention was pumped into the developer tray, fed from the same storage bottle as the cleaning solution. This was followed by pumping in 22ml developer replenisher. 30ml bleach-fix developer and replenisher were pumped into the bleach-fix tank. The mixture was stirred for about 15s by starting the agitation rollers at a rate of 1Hz. The replenisher pumps were started and a length of paper inserted into the machine. This was carried out for both the control comparison and in accordance with the invention.

The strips were allowed to dry at room temperature and then the densities read with a densitometer at 1 cm intervals. The results of the experiment are shown in Figures 1 and 2.

After processing the processor was washed in the same way as before processing. No crystals were seen with either the water or the starter/processor cleaning solution. The results show that the change in density was much greater with the comparison process, in which water was used as the starter and wash solution, as compared to the invention with the hydrochloric acid wash. No residue was seen in the tank when using the method of the invention This demonstrates that a starter solution containing only volatile materials can also be used to wash the processor and be delivered from the same storage bottle.

Example 2

Example 1 was repeated with an alternative starter/processor cleaning solution and a faster process:

Starter/Processor Cleaning solution

0.00075 mole/litre hydrobromic acid to which was added 2g/l Tween 80

Figure 3 shows the effect of seasoning with no starter/processor cleaning solution added to the replenisher in the tray at the beginning (the control comparison). Figure 4 shows the effect of seasoning with starter/processor cleaning solution added to the replenisher in the tray at the beginning, in accordance with the invention.

It will be understood by those skilled in the art that water is not a "solution" as required and defined by the present invention.

It will be further understood by those skilled in the art that the invention is not limited to the use of the cleaning solution as a starter solution. It will be understood by those skilled in the art that the cleaning solution could also be used as a stop solution for use after a developer or before a bleach/fix or fixer.

The invention has been described in detail with reference to preferred embodiments thereof. It will be understood by those skilled in the art that variations and modifications can be effected within the scope of the invention.

Claims

Claims:

1. A method of processing in which the cleaning solution for washing the processor comprises at least a constituent part of the processing solution.

2. A method as claimed in claim 1 wherein the same solution is used for both a starter solution and for the cleaning solution.

3. A method as claimed in any preceding claim wherein the cleaning solution comprises hydrochloric acid.

4. A method as claimed in any preceding claim wherein the cleaning solution comprises hydrobromic acid.

5. A method as claimed in any preceding claim wherein the cleaning solution comprises hydroiodic acid.

6. A method as claimed in any preceding claim wherein the processing solution is developer.

7. A method as claimed in claim 1 wherein the same solution is used for both a stop solution and for the cleaning solution.