WO1991017478A1

WO1991017478A1 - Method of processing photographic material

Info

Publication number: WO1991017478A1
Application number: PCT/EP1991/000844
Authority: WO
Inventors: John Richard Fyson
Original assignee: Kodak Limited; Eastman Kodak Company
Priority date: 1990-04-30
Filing date: 1991-05-01
Publication date: 1991-11-14
Also published as: GB9009677D0

Abstract

The amount of retained developer in photographic material is reduced by subjecting a processing solution through which the material passes after development but before washing to the influence of an absorbing agent. The absorbing agent may be an ion exchange resin or an activated carbon.

Description

METHOD OF PROCESSING PHOTOGRAPHIC MATERIAL

This invention relates to a method of processing a photographic material and is particularly, though not exclusively, concerned with processing developed colour print material carried on a paper backing. It is, however, also applicable to material, either colour or black and white, carried on a film backing, and also black and white material on a paper backing.

In a photographic development process photographic material is successively passed through a number of steps which include serially developing, other ^■ processing steps and washing. The final washing step removes chemicals from the material to ensure it is stable and no subsequent chemical action takes place. The post development processing step may comprise a plurality of individual steps where the material is successively treated to solutions in baths each of which has a different effect on the material. Thus the processing steps may include treating the material in baths containing respectively stop, bleach, fix or bleach-fix solutions. If the developing agent is not efficiently removed from the processed material, staining can occur.

This is particularly so in producing colour prints. If this does happen then staining and marking of the print can subsequently take place since the developer will continue to act, particularly under conditions of light and heat exposure.

In order to avoid staining it is the practice for the prints to be subject to a very intense washing process to ensure that all the retained developer is removed.

The need to remove the retained developer requires a substantial amount of washing either under a constantly moving flow of water or by taking the print through a series of wash tanks where chemicals including the retained developer are washed from the print.

If the amount of washing necessary is able to be reduced then the apparatus for processing the print becomes cheaper in price as a lower number of tanks are needed and, furthermore, there is conservation of water, since less water is necessary for washing. As a result of this the effluent from the process is reduced.

It is an object of the present invention to provide an improved method of processing a photographic material in which the retained developing agent is substantially reduced before the material is subjected to washing.

According to the present invention, a method of processing a photographic material including developing and washing steps is characterised in that in one or more of the processing steps after development but before washing, the processing solution is treated with an absorbing agent in order substantially to reduce the amount of retained developing agent in the solution.

Preferably the absorbing agent is introduced in the last active stage of a photographic process and this stage is normally the fixing or bleach-fix stage. The absorbing agent is preferably an ion exchange resin. The resin may be cationic, anionic, neutral or a mixture of cationic and anionic.

Alternatively, the absorbing agent may be constituted in the form of activated carbon such particularly as activated charcoal.

The invention will now be explained with reference to the single figure of the accompanying drawing which shows schematically the tail-end layout of a photographic process where, after a developing step, a developed film is subjected to fixing and then to four washing steps.

In the drawing the photographic print material which, in this example is on a paper base, is introduced into a bath 1 which contains a fixing solution. The paper is transferred successively from the fixing solution to washing tanks 2, 3, 4 and 5 which have water flowing through them in the direction of the arrow A which is contrary to the paper direction which is shown by the arrow B. The tank 1 has bypass inlet and outlet tubes 6 which circulate the fixing solution through a cartridge 7 which contains an absorbing agent, such as an ion exchange resin or an activated carbon.

The fixing solution is constantly replenished and surplus solution falls over a weir to an outlet pipe 8 to silver recovery apparatus 9 and then passes via an outlet 10 to the drain.

In operation the fixing solution is in the last active tank 1 of a processing step and the print material is carrying on its surface and in its gelatine remnants of the developing agent when it enters the solution in tank 1. While the material is processing through the tank 1 the solution is subjected to the effect of the absorbing material in the cartridge 7 and this draws out the developing material from the print and either absorbs all the developing material or, alternatively, reduces it to such a low level that it will no longer have a staining effect. If there is some retained developing agent left in the print material when it leaves the tank 1 this will be eliminated or substantially eliminated during the washing process in tanks 2, 3, 4 and 5, where the print is subjected to a fresh water flushing wash, which not only would remove the residue of the developing agent but also other chemicals. Thus it will be appreciated that as the developing agent moves from tank to tank it is diluted during the washing operation in successive tanks and the amount in each tank is governed by the amount carried over in the gelatine layers from the previous tank as well as by the flow rate of the water in the tanks.

Two specific examples will now be described by way of illustration of the use of the equipment shown in the Figure.

EXAMPLE 1

An experimental model processor was set up such that the tailend was as shown in the Figure. The colour developer removing cartridge 7 was filled with 400g of activated charcoal. The developer in the preceding bath was a standard Kodak (RTM) RA4 solution. Carry over from each bath, including the developer, was simulated using peristaltic pumps each set at 3 mls/min. This model was used to conserve paper and to allow for speedy seasoning. The fixer replenishment rate was set at 5ml/min and the wash flow rate set at lOmls/min. The fixer was :

sodium thiosulphate tetrahydrate 20g sodium sulphite (anhydrous) 20g acetic acid (glacial) 10ml. pH adjusted to 5 with sodium hydronitrate

This simulated a processor processing 0.0929m² of material per minute. The volume of each of the tanks was about 300mls. The model processor was allowed to run for 20 hours until the "process" was seasoned.

After this a piece of unexposed Ektacolor (RTM) 2001 paper was "processed" by dipping it into each tank successively from left to right in the Figure. The strip was then allowed to dry and put in an oven at 60°C/60%RH for one week. The blue status, status

A density was measured. The experiment was repeated with the charcoal cartridge removed and using the same wash flow rate of lOmls/min and also at 30mls/min. This latter rate is similar to the present RA4 process. The results are tabulated below. As can be seen the staining with developing agent removal with a flow rate of lOmls/min is as good as the normal process with 30mls/min. The process without developing agent removal and with the low flow rate had more staining.

CD Removed Standard Reduced flow and reduced flow RA4 RA4

Blue Stain 0.08±0.01 0.08-tO.Ol O.ll±O.Ol Density

In the second example, different types of absorbing agent were tested to see the effect they would have on removing a standard colour developing agent.

EXAMPLE II

A simulated seasoned fix was made by adding 300mls of a developer/amplifier to 500mls of a fixer suitable for use with low silver materials. The formulae are as follows:

pH adjusted to 10.3 with potassium hydroxide solution just before processing 5mls 30% hydrogen peroxide was added to this developer.

Fixer:

sodium thiosulphate lOg sodium sulphite (anhydrous) 20g water to 1 litre pH adjusted to 4.9 with acetic acid

50mls samples of the fixer/developer mixture were stirred with 5g of different resins or charcoal for 10 minutes. The residual CD3 in the fixer mixture was determined by HPLC. The results are tabulated below:

Addition Residual CD Resin Type

None 4.5±0.2g/l

Amberlite XAD-2 1.6±0.2g/l Neutral Amberlite XAD-7 0.6+0.2g/l Neutral Amberlite IRA-400 3.1+0.2g/l Anionic Duolite C225 3.0+0.2g/l Cationic Duolite MB5113 2.6+0.2g/l Mixed bed Zerolit NIP 2.8+0.2g/l Anionic Zerolit 236 2.1+0.2g/l Cationic Activated charcoal 0.4+0.2g/l Cationic

All the above addenda removed the CD3 to some extent.

It will be noted that the absorbing agents used are all standard commercially available agents. The amberlite agent from Rohn & Haas Co., Duolite from The Diamond Shamrock Corporation and Zerolit from

Permutit. All these agents are known for their ability to react with a developing agent and have been used in recovery solutions, for example as is disclosed in U.S. Patent 4606827 or British Patent Publication No. 2054182A. In these prior art applications there has been the use of the absorbing materials to treat solutions at the end of a process and not as part of it. By the use of the present invention the absorbing agent is added to the last active path of a process and while the fixing is taking place, the retained developing agent is simultaneously removed and reduced.

In practice, this leads to a much more compact and water- efficient and, hence, more economical method of treating the material than has hitherto been available.

Claims

1. A method of processing a photographic material, including developing and washing steps characterised in that in one or more of the processing steps (1) after development but before washing, the processing solution is treated with an absorbing agent (7) in order substantially to reduce the amount of developing agent in the solution.

2. A method as claimed in claim 1 characterized in that the absorbing agent (7) is included at the fixing stage (1) of a photographic process.

3. A method as claimed in claim 1 or claim 2 characterized in that the absorbing agent is an ion exchange resin.

4. A method as claimed in claim 3 characterized in that the resin is cationic.

5. A method as claimed in claim 3 characterized in that the resin is anionic.

6. A method as claimed in claim 3 characterized in that the resin is neutral.

7. A method as claimed in claim 3 characterized in that the resin is a mixture of cationic and anionic resins.

8. A method as claimed in claim 1 or claim 2 characterized in that the absorbing agent is an activated carbon.

9. An absorbing agent as claimed in claim 8 characterized in that the activated carbon is activated charcoal.