FR2480450A1 - METHOD AND APPARATUS FOR PREPARING PHOTOGRAPHIC PROCESSING SOLUTIONS AND CONTAINER FOR USE IN THIS PROCESS - Google Patents

Abstract

A method and apparatus for admixing liquid with a shear-thinnable concentrate (11) of photographic processing composition to form a photographic processing solution, in which the concentrate is thinned by shear forces and contacted with the diluting liquid under turbulent mixing conditions to dissolve the concentrate in the liquid and thereby form the solutions. The concentrate, which does not flow and resists deformation under conditions of low shear, is displaced from a tube-like container (13) through an orifice (37) where conditions of high shear render it free-flowing and form a stream. One or more liquid jets (51, 53, 55) are directed at the stream with sufficient force to disperse the concentrate under turbulent mixing conditions. A mixer (57) then completes the dissolution of the concentrate in the liquid.

Description

 The present invention relates to a method and an apparatus for preparing photographic processing solutions by mixing photographic processing concentrates with liquids so as to form processing solutions. More particularly, the invention relates to such a method and such an apparatus operating from treatment concentrates having a paying consistency, these concentrates being able to be fluidized by the application of mechanical shear stresses. The invention also relates to a container for such concentrates, this container being usable in the method and in the aforementioned apparatus.

In the following, "photographic processing solution" will be understood to mean all solutions such as liquid developers, renewal solutions, "starting" solutions or any other photographic processing solutions ready for use.

 Conceived photographic processing compositions are commonly provided in the form of liquids, powders, tablets and even post or gels which are diluted in water to form the photographic processing solutions.

 Concentrates in liquid form are generally preferred by professionals in photographic processing, no doubt because of the simplicity of the equipment necessary to dispense these concentrates and to dilute them. These liquid concentrates are supplied, for example, in plastic bottles closed by a frangible membrane and by a protective capsule. Once the cap has been removed, the bottle is overturned above a receiving tank comprising a punch which pierces the membrane to cause the liquid to flow.

Water is added to dilute the mixture to the concentration suitable for a photographic processing solution.

 Although liquid concentrates are widely used, powder concentrates have certain advantages, particularly with regard to their storage and shipping. For example, amateur photographers often prefer powdered concentrates because of their small footprint and long shelf life.

However, most powdered concentrates are considered difficult to dissolve and dilute. Although there is no doubt satisfactory equipment for this purpose, these are either bulky or designed only for small production volumes. They are not particularly convenient for inexperienced operators or when used with large capacity automatic processing. In addition, the use of powder generates dust and spillage during the measured discharge and mixing operations.

 Some of the problems associated with powders can be overcome by compressing them into tablet form. However, these are not likely to replace powders, commercially.

The tablets cannot contain liquids and many photographic processing compositions cannot be packaged in tablet form. Those which are usually include binders which may make it difficult to dissolve the tablet and / or which may cause undesirable sensitometric effects during treatment. The effervescent products used to promote rapid dissolution are generally ineffective, costly and generate complications at the manufacturing stage.

We have also proposed formulas for photographic processing concentrates suitable for presentation in the form of a paste. For example, the English patent 4689 describes black and white developer concentrates having the consistency of a paste or a cream, the Italian patent 427 967 describes black-white developer concentrates presented in the form of a paste, the State patent - United States of America 2,735,774 describes fixative concentrates of pasty consistency and United States patent 2,784,086 describes black-white developer concentrates whose formulation makes it possible to produce a smooth gel.

Although thought has been given to using pastes and viscous solutions or photographic gels, the prior art does not find the means suitable for using the pastes so as to obtain all the possible advantages. The properties of the dough formulas described in the prior art have prevented their use.

It appears that the pasta was manually removed from their storage container and that it was mixed by manual stirring or other similar techniques. For this and other reasons, most pasta was relatively soft and contained an excessive amount of water. Low water rich pastes were considered difficult to dissolve and had some of the disadvantages of tablets. In the description which follows, it will appear that the present invention overcomes many of the disadvantages of the prior art and provides substantial new advantages.

In accordance with the present invention, there is provided a method and apparatus for preparing photographic processing solutions by mixing photographic processing concentrates> having a pasty consistency with diluting fluids. The concentrates take the form of firm pseudo-plastic pastes which behave in many respects like a solid but which are fluidifiable under the action of shear stresses, which greatly facilitates their dumping.

Once fluidized by shearing and brought into contact with a dilution liquid, under turbulence, the concentrate disperses and dissolves easily to give rise to a solution.

 According to a preferred embodiment of the invention, the pattu concentrate is poured: from its container through an orifice which forms a flow which is fluidized by shear stresses created in the orifice. The flow passes through a primary mixing chamber into which a dilution liquid is introduced in the form of one or more jets which strike the flow with sufficient force to disperse the concentrate and establish intimate contact between the concentrate and the liquid, under turbulence. . In addition, a mixer with internal fixed baffles is used to establish additional agitation and complete the dissolution of the concentrate in the liquid.

In the accompanying drawing, given only by way of example
FIG. 1 is a partial section view of a tube-shaped container according to the invention suitable for containing a photographic processing concentrate,
- Figure 2 is a sectional view of part of the apparatus according to the invention, for forcing the treatment concentrate through an orifice so as to fluidize the concentrate by shearing forces and for bringing into intimate contact the fluidized concentrate and a liquid so as to dissolve the concentrate in the liquid, and
- Figure 3 is a perspective view of the apparatus according to the invention, for mixing a photographic treatment concentrate, fluidifiable under the action of shearing forces, and a liquid, to constitute a treatment solution
FIG. 1 shows a preferred embodiment of a container according to the invention. The container comprises a concentrate of a photographic treatment composition 11 which can be fluidized under the action of shear forces, this concentrate being placed in a dispensing tube 13 for dispensing the concentrate to a dilution apparatus 15 (FIG. 3).

The concentrate comprises continuous phases and discontinuous phases combined so as to form a highly viscous concentrated paste having a physical stability very close to that of a solid.

The paste is pseudo-plastic and fluidizable by shearing, which means that its viscosity can be significantly reduced when it is subjected to a shearing such as that which appears when the concentrate is forced through a throttling orifice. Subject to such high shear, the concentrate behaves, from the point of view of its flow, rather like a fluid. It flows freely and, according to the method described below, it can be conveniently dispersed and dissolved in a liquid such as water. In other words, the concentrate is very viscous under low shear but its viscosity decreases under high shear.

 The photographic processing concentrate, in itself, is described more fully in the French patent application filed today by the applicant and entitled "Concentrates for photographic processing". In general, the treatment concentrate contains liquid phases and solid phases. The continuous liquid phases can comprise a single liquid, two or more liquids. It can be only water, only one or more body fluids or a mixture of body fluids and water. The solid phases comprise one or more of the ingredients of the processing composition, these ingredients usually being solids. Although liquid or solid ingredients which may not be necessary components of the dough may be incorporated into the dough the photographic solution ready for use, the paste is frequently prepared only from the necessary components of this treatment solution, without the need to abandon any of the ingredients used in the liquid concentrates of the prior art nor to add additional ingredients. In other words, the formulation of the stable concentrate can be achieved by the sole choice of the relative proportions of the ingredients, by the choice of the particle sizes of the ingredients, and by the adjustment of the process according to which they are combined.

The physical stability of the concentrate under low shear is an important characteristic of this concentrate. In this state, the concentrate has a behavior very close to a solid. It resists deformation and cannot easily spread. These properties are of course very useful with regard to the storage and shipment of the concentrate, but one could normally consider that they make the distribution of the concentrate difficult, in particular in measured quantities.

However, it has been realized that other properties of the concentrate can be used to facilitate its distribution, without requiring the addition of more water to this concentrate. When properly agitated or otherwise subjected to shear forces, the concentrate becomes fluid and can flow freely. Its viscosity decreases, the concentrate can easily deform to move in tubes and conduits, and it can be dispersed and easily dissolved in water to form a photographic treatment solution.

The particular viscosity achieved and the extent of shear thinning obtained vary greatly with the wide variety of different processing concentrates. For example, typical concentrates have an apparent domain viscosity ranging from 250 to about 1300 centipoise and a shear rate of 800 s l. At a rate
-l of shear of 4500 s, we commonly observe an apparent viscosity between about 100 and 500 centipoise, respectively. These values are obtained by measurements made with a viscometer called "HI-SHEAR" from the company of the United States of America called Hercules, at room temperature. This viscometer is of the rotary cylinder type.

During these measurements, the rotor (or inner cylinder, 1.95 cm in radius and 5 cm in height) rotates with a constant angular acceleration of approximately 5.49 rad / sec2 to reach a maximum angular speed of 115 rad / s . This rotation communicates an increasing shear rate -l (with a maximum of 4549 s) to the sample contained in the annular volume which separates the interior and exterior cylinders, this annular volume having a width of 0.5 cm. The torque transmitted to the outer cylinder by the sample is measured and this measurement is used to calculate the apparent viscosity as a function of the shear rate.

The expression "photographic processing concentrate" is used here to denote a product used to develop or otherwise treat a photographic product, for example to develop, fix, whiten, tan, stabilize, etc. Thus, the processing solutions prepared from the concentrates described here can be any of the solutions used to process photographic products such as for example black-white developer solutions, color developer solutions, fixing baths , whitening baths, stabilization baths, stop baths, nucleation baths, monobaths, whitening-fixing baths, pre-tanning, conditioning activating baths, reinforcing baths, neutralization baths, etc.

 The container 13 takes the form of a plastic tube with relatively thin walls, having a neck 19 defining an opening 20 formed at one end of the tube, and a pressure applying device such as a movable bowl 21 which adjusts tightly into the body of the tube, at its other end. Before use, the neck is closed by a frangible membrane 23 and by a protective cap 25 to make the container impermeable to the penetration of atmospheric gases and to the diffusion of the concentrate. Thus, the tube protects the concentrate from deterioration and, as will appear clearly in the description which follows, it also serves to dispense the concentrate to a dilution apparatus.

Once the cap is removed and the membrane is torn, the concentrate can be taken out of the tube through the opening 20 by applying a force against the bowl 21. Thus, in addition to the protection established by the tube for the storage and shipping of the concentrate , this tube greatly facilitates the direct distribution of this concentrate to the dilution apparatus, without the intervention of intermediate holding boxes or other similar bodies. The tube also facilitates obtaining a measured distribution of the concentrate, that is to say that the concentrate can be removed from the tube per measured volume, while thus establishing great consistency in the distribution of the active ingredients.

 Photographic processing chemicals must be dissolved in water or other liquids in very precise amounts to prepare fresh solutions; thus, to be commercially useful, a photographic concentrate must not only be easy to package, to ship and to keep, but also be able to be debited with the necessary precision in the preparation of ready-to-use treatment solutions. It is particularly advantageous for this concentrate to be able to be delivered per measured volume. By this is meant that the concentrate must be able to leave its container in a quantity measured by volume, with very good reproducibility such that each unit of volume distributed contains practically the same quantity of active agent, by weight. it is possible to mix a predetermined volume of centered con 3 with a predetermined volume of liquid, for example 100 cm of concentrate in a liter of water and to obtain, in a reproducible manner, the same weight of active agent in the solution resulting.

The dilution ratio used with the concentrate, that is to say the amount of water or other liquid used to transform the concentrate into a ready-to-use treatment solution, varies greatly depending on the photographic product to be treated, of the treatment process, and particular treatment formulations involved. In general, this dilution ratio is in the range from one part of concentrate with 8 parts by weight of liquid to one part of concentrate with 100 parts by weight liquid.

 The opening of the tube is reduced relative to the body of the tube, so as to maintain a reasonably compact configuration while reducing the area of the section through which the concentrate leaves the tube to go into the dilution apparatus. In addition, and as will appear in the description which follows of this dilution apparatus, the walls of the tube need not be strong enough to withstand lr-- forces necessary to bring out the whore from the tube, since the the dilution apparatus may include an additional holding member.

 container is designed to be used in a dilution apparatus comprising a receptacle 27 suitable for receiving the container, a zone 29 for shear thinning (FIG. 2), a pressing mechanism 31 and one or more mixing chambers 33.

 The receptacle comprises a cylindrical sleeve 35 of a shape complementary to that of the tube 13, this sleeve constituting an assitoinnel support which prevents the tube from deforming under the pressure of the concentrate, when the latter moves in the tube.

 The fluidization zone 29 contains a conical injector 37 mounted on the neck of the dispensing tube. In the preferred embodiment of the invention, this injector replaces the protective cap of the tube.

It is clear however that this injector can be part of the tuba itself or else be incorporated into the mixing device. Similarly this conical injector could also take the force of a circular opening without longitudinal extension, or or with a short extension. The injector shown above increases the distance over which the concentrate is subjected to shearing and, when the section of this injector decreases from its base towards its end, the shearing forces can be increased as and when fluidization of the composition. As a stopper, the end of the injector can be cut to a level chosen to define the desired end section for this injector. Thus, it is possible to use only one type of injector for different concentrates having different shear thinning. Whatever the type of orifice used, it must substantially thin the concentrate, so that it can flow through this orifice.

 The pressing mechanism uses a pressure of water applied against the bowl to plastically deform and fluidize by shearing the concentrate while forcing it, through the opening of the neck of the tube, into the injector. More particularly, a shutter 41 is fixed to the end of the cylindrical sleeve and presses tightly on one end of the tube 13 so that the pressure of the cuvette water can be applied to the conduit 45 of pressurized water which opens with a nozzle 43 near the bowl.

 The mixing chamber 33 actually has two parts. The first part, constituted by a primary mixing chamber 47, comprises a primary inlet orifice 49, through which between the concentric, and at least and preferably several, j1 inlet orifices 51, 53 and 55 through which a liquid of dilution comes into contact with the concentrate.

In FIG. 3, it is seen that the liquid is directed by the jets inlets towards the center of the fluidized concentrate which flows from the end of the injector. The liquid jets strike the concentrate flow with sufficient force to disperse it and to establish intimate contact between the concentrate and the liquid, under conditions of turbulence favorable to mixing. The jets enter the mixing chamber at an angle of about 30 relative to the flow path of the concentrate and these jets are directed towards the center of the chamber. Of course, other suitable arrangements could be used. For example, one could orient the jets at 90 and make them tangential to the flow of concentrate.

 The second part of the mixing chamber consists of a static mixer 57 which communicates with the outlet of the primary mixing chamber 33 and which performs additional stirring to complete the dilution of the concentrate in the liquid. Mixer 57 is provided with internal baffles and may take the form of that shown in United States patent 4 093 188.

From chamber 33, the diluted composition passes for years at reservoir 61, by means of a nozzle 59, the solution received in reservoir 51 then being ready for use.

In its preferred embodiment, the method according to the present invention consists in applying shear forces to a photographic processing concentrate which can be fluidized by shearing in order to fluidize this concentrate, then in contacting the fluidized concentrate and a dilution liquid under conditions mixing under turbulence, to make a photographic treatment solution. Shear is obtained by forcing, for example1 the concentrate through a pressurized orifice, so as to form a flow which is dispersed with one or more jets of liquid. The dispersed flow is then repeatedly divided in a mixer comprising internal fixed baffles so as to complete the dissolution of the concentrate in the liquid.

In its simplest form, the container according to the invention containing a predetermined quantity of the concentrate. The container is then completely emptied into the dilution apparatus, which adds a predetermined quantity of the dilution liquid to it. The addition of this liquid preferably begins simultaneously with the dispensing of the concentrate and continues for some time after the container has been emptied, to ensure that all of the concentrate passes from the mixing chambers into the tank.

 It is now clear that the present invention provides significant advantages which do not result from the teachings of the prior art. The concentrate can be supplied and used in a manner which has both the advantages of powders and liquids. Before fluidification, the concentrate behaves almost like a solid which resists displacement under the effect of gravity or an overflow and which lends itself perfectly to a conservation or a shipment. After fluidization the concentrate flows freely, moves easily in tubes and conduits and conveniently dissolves in liquids such as water when mixed under turbulence.

The container is preferably completely filled to exclude any gaseous phase.

Claims (12)

1. Process for the preparation of a photographic treatment solution at  from a flowable concentrate by shearing, this process being  characterized in that:  a) the concentrate is expelled from a container through an orifice, to thin by shearing this concentrate and to form a flow of this concen very, and  b) the concentrate thus fluidized is brought into contact, under turbulence, and  a liquid to dissolve the concentrate in this liquid and obtain  said solution. 2. Method according to claim 1, characterized in that it directs  a liquid jet towards the flow of the fluidized concentrate, with a force sufficient to disperse this concentrate and the concentrate and  liquid to dissolve the concentrate. 3. Method according to claim 2, characterized in that one continues  applying the jet of liquid for a predetermined period of time  mined, after emptying the container. 4. Method according to claim 1, characterized in that it distributes  the concentrate in predetermined quantity and in that we add a  predetermined amount of liquid. 5. Method according to claim 2, characterized in that one passes the fluidized concentrate in a mixing zone and in that one directs  then at least one jet of liquid towards this concentrate with a force sufficient to disperse it and establish intimate contact between  the concentrate and the dilution liquid in this mixing zone, in  mixing conditions under turbulence, to establish a first  mixture of the concentrate and the liquid and we direct the effluent coming out of  this mixing zone in a mixer which establishes a stirring  additional of this effluent, so as to complete the dissolution of the  concentrated. 6. Apparatus for implementing the method according to claim 1, characterized in that it comprises:  a) a means for delimiting a constricted orifice,  b) a means for passing the concentrate through this orifice  so as to thin it by shearing and  c) mixing means for bringing the fluidized concentrate into contact  by shear and dilution liquid, so as to disperse and dissolving the concentrate in the liquid to form said solution. 7. Apparatus according to claim 6, comprising a mixing chamber  and means for simultaneously introducing the fluidized concentrate by  shear and liquid in this chamber, to mix under  turbulence the concentrate and the liquid  8. Apparatus according to claim 7, characterized in that it comprises  (1) a mixing chamber provided with an inlet orifice through which the fluidizable concentrate by shearing at least one inlet  secondary and an output,  (2) means pçnss introduce the liquid into this chamber through the inlet  secondary in the form of: a jet directed towards the fluidized concentrate  to disperse it and establish intimate contact between the concentrate  and the liquid in this chamber, under turbulence, and  (3) a mixer, fitted with internal fixed baffles, communicating with the  leaving the room for asaures an additional agitation of the ef  fluent from this room, so as to complete the dissolution of the concentrated in the liquid.  9.Concentrate for photographic processing, usable in the process according to claim 1, characterized in that it comprises  (1) a concentrate of a fluid photographic treatment composition  reliable by shear formed, at least for the most part, from a phase  discontinuous and a continuous phase, in proportions which give this concentrate the consistency of a firm dough and,  (2) a distributor to supply this concentrate to a dilution device, this distributor comprising a throttled outlet orifice and means to apply pressure to this concentrate to force it through  this orifice. 10. Container according to claim 9, characterized in that the orifice  of this distributor constitutes an injector which cooperates with an apparatus for  dilution to direct the concentrate into a mixing chamber of this  device, this injector acting so as to thin by shearing  this concentrate. 11. Container according to claim 9, characterized in that the said dispenser includes a frangible shutter that closes the outlet so that, when this shutter is intact, the container is  impermeable to penetration by atmospheric gases or to diffusion  outward of said concentrate. 12. Container according to claim 11, characterized in that the con  centered completely fills the container, to exclude gas phases  from this container.