EP0061062A1 - Device for limiting the transfer of treating liquids - Google Patents

Abstract

In a device for limiting the entrainment of treatment fluids (2, 3) by sheet- or strip-like materials (1) during the chemical treatment thereof in processing tanks (I, II), two tubular rollers (4) of a porous material are provided, the topside and underside of the sheet- or strip-like material (1) being brought into contact with the surface of the porous material for extraction of the treatment fluid (2, 3). The tubular porous rollers (4) are connected at the end face to a vacuum generator and to a separator, so that the extracted treatment fluid (2, 3) can be returned into the particular processing tank (I, II).(Figure 1). <IMAGE>

Description

The invention relates to a device for reducing the carry-over of treatment liquids by sheet-like or ribbon-like materials during their chemical treatment in processing baths.

A wide variety of sheet-like or ribbon-like materials are subjected to a chemical treatment after their production, for example to refine their surface, such as by electroplating, anodizing or to develop photographically exposed films or papers in the photographic industry.

For this purpose, the materials are introduced into baths with chemicals and a large part of them are dragged out of the baths. the chemicals in subsequent baths or in water baths that wash off or dissolve the chemicals.

The chemicals used often contain toxic substances that endanger the environment and therefore may only be present in the wastewater in very small, legally prescribed amounts. The wastewater must therefore be subjected to an ecological treatment before being discharged into the sewer in order to remove the toxic chemicals in the wastewater. In addition, the carryover of chemicals creates losses in the bath from which the materials that have to be replaced have to be removed and contaminants in the subsequent baths that require regeneration.

This problem also exists in the processing of imagewise exposed photographic materials by developing, bleaching, fixing and washing. The processing takes place in so-called development machines, which lead the material to be processed through a large number of processing tanks, some of which is rinsed with chemicals after each processing stage in order to wash off or remove the chemicals from the processing stage. The washing baths are enriched with toxic substances and must be treated before they enter a sewer.

With normal utilization of a developing machine for developing photographic materials, the final washing bath contains between 10 and 150 mg of silver per liter of water. The amount of toxic substances carried into the washing bath (e.g. from bleach-fix baths) is proportional to the silver concentration.

Successive processing baths without intermediate watering are also known, it being important that as little bath content as possible is carried over from one tank to the next tank so that, for example, photochemical reactions can take place in the desired manner and speed.

The amounts of chemicals carried away by the materials depend on the one hand on the surface structure of the materials themselves, whereby rough surfaces carry off more chemicals than smooth surfaces, on the other hand there is a strong dependence on the nature and surface structure of the nubbed, grooved used in the different brands of processing machines or transport rollers covered with synthetic fiber fabric, which determine the degree of surface wetting in ml / m ² . The processing methods currently in use require the addition of up to 500 ml of bleach-fixing bath and up to 700 ml of developer to compensate for carry-over or for regeneration for every m ^{2 of} photographic material that is being processed.

It is known to free the materials emerging from the baths with rubber scrapers from part of the processing liquid adhering to the surface. This procedure can only be carried out in facilities that only process rolls. In many common facilities, for example in the development of photo paper, rolls of various widths and numbers as well as individual sheets up to a format size of 140 cm x 200 cm are used is working. The rubber wipers hinder and disrupt the flow of format sheets and can easily damage the photographic emulsion layer, which is particularly sensitive when wet, even on rolls.

The use of squeeze rollers to retain the processing liquids and to reduce the amount of surface wetting of the material is also known. With a longer material throughput, these squeeze rollers are no longer fully effective, since the processing liquid jams on the inlet side, is taken as a film from the squeeze rollers to the outlet side and is released again to the material. Suctioning off the processing liquid with vacuum nozzles on the inlet side of the material shows only a limitedly usable improvement in reducing the carryover of processing liquids.

So far, therefore, no satisfactory technology is known, with the aid of which intended and advantageous low carry-over amounts from bath to bath can be achieved and the carry-over amounts can be reproduced.

The invention is therefore based on the object of providing a device of the type mentioned in the introduction, with which it is possible in a simple manner to reduce the carry-over amounts by sheet-like or tape-like dimensions to keep materials as low as possible during their treatment in chemical baths and to make the amounts of carry-over reproducible for similar materials.

The object is achieved according to the invention for a device of the type mentioned at the outset in that two tubular rollers made of a porous material are arranged behind and / or above the treatment bath transversely to the direction of travel of the sheet or strip-shaped materials, that the tubular rollers are connected to a vacuum generator on the end face and a separator for the treatment liquid are connected and that the sheet or strip materials can be guided so that their top and bottom sides each touch or loop around a tubular roller for suction of the treatment liquid.

A special embodiment of the device is characterized in that a tubular, porous pair of rollers under negative pressure for processing photographic materials in roller developing machines is arranged at least before a transition of the photographic material from one treatment bath to a next and / or behind the last treatment bath that each side of the photographic material comes into contact with a tubular roller or partially encloses a roller.

It was surprising for the person skilled in the art that with the simple device an almost complete suction of the treatment liquids and the chemicals contained therein from sheet or strip materials is possible. When the sheet-like or ribbon-shaped material wetted on the front and back with liquid chemical solutions passes through this pair of rollers, the chemical solutions are sucked off the surfaces by the porous material of the tubular rollers and collected in a separator, from which they can be returned to the processing bath . The negative pressure prevailing on the surface of the porous rollers is almost constant over the entire width of the rollers in the axial direction, so that the surfaces are extracted very gently without being damaged. The vacuum in the tubular rollers can be set as desired, so that the suction performance can be selected and, above all, always reproducible.

The very minimal carry-over of processing chemicals remains the same when processing the same materials, so that only a small and constant amount of processing chemicals has to be added or regenerated. A material, which has to go through several processing baths, can be adjusted to a reproducible constant humidity by the device after the last bath, usually a washing bath, whereby an overcapacity for the trok power must not be provided. The drying capacity can rather be set to a considerably smaller value.

In an advantageous embodiment of the device, the porous material for the tubular rollers consists of a sintered plastic and has pores in a size of 50 μm to 300 μm. A smoother roller surface is achieved with pore sizes from 100 µm to 200 µm, whereby these pore sizes are also large enough to completely suck the chemical solutions off the surface.

In order to improve the stability of the rollers, particularly in the case of very wide rollers, it is advantageous if the tubular rollers are provided on the inside with a support core made of a corrosion-resistant metal, preferably stainless steel.

For the production of porous tubular rolls, in addition to sintered plastics, e.g. Polyethylene, other materials such as glass, pumice or the like are used.

In a particularly advantageous embodiment, which is characterized by high stability, a corrosion-resistant sintered hard metal is used as the porous material for the tubular rolls, which has pores in a size of 50 to 300 microns. Such sinter hard metals are manufactured industrially in all dimensions and shapes and consist of a sintered stainless steel powder.

In order to avoid speed differences between the sheet or sheet materials and the rollers, the tubular rollers are additionally driven in the usual way, e.g. through spur gears or belts, if they are not wrapped in a small area by a web-shaped material and are thus driven by the web without slippage.

When using the device to reduce carryover of processing fluids in photographic processing machines, e.g. in roller transport developing machines, it is advantageous if the tubular rollers are part of a roller transport developing machine for photographic materials and are arranged as the last pair of rollers at the outlet of the photographic material from a processing tank above the surface of the treatment liquid.

_B lattiform or strip-shaped materials are combined for treatment in processing liquid to form a band in succession by stapling or sticking together. Frames are often used, in which the materials for treatment are clamped. A white is distinguished for these materials Further development of the device in an advantageous manner that the tubular rollers of the pair of rollers are resiliently mounted on levers and are spaced apart in their distance when passing through holding or clamping devices between the rollers.

The device is advantageously suitable for suctioning off chemical solutions to avoid carry-over into other baths and for recovering the chemical solutions, which can usually be pumped back into the processing tanks without treatment. When processing photographic materials, it is surprisingly shown that not only the chemical solutions adhering to the surface are suctioned off, but also the chemical solution which has penetrated into the photographic layers, which consist of gelatin emulsions, is reduced. The use of the device after the last washing bath in photographic materials allows predrying, which saves a considerable amount of heat energy for drying. If the device is used to treat air-permeable sheet-like or tape-like materials, e.g. air-permeable papers, textiles or fabric-like foils, an even greater drying effect is achieved, especially if the materials wrap around the porous, under-pressurized rollers on a longer path. In this case, one roller is sufficient to achieve a significant liquid withdrawal.

• Fig. 1 eine Zweibäder-Verarbeitungseinrichtung mit dazwischen angeordneten rohrförmigen porösen Walzen, die ein blatt- oder bandförmiges Material beidseitig berühren.
• Fig. 2 eine Verarbeitungseinrichtung nach Fig. 1 bei welcher ein blatt- oder bandförmiges Material die porösen rohrförmigen Walzen umschlingt.
• Fig. 3 eine Verarbeitungseinrichtung nach Fig. 1, bei welcher die porösen rohrförmigen Walzen in die Verarbeitungseinrichtung integriert sind.
• _Fig. 4 rohrförmige poröse Walzen, die schwenkbar gelagert sind.

The invention is described below for the embodiment of a photographic development of imagewise exposed photographic sheet or tape-shaped films or papers with reference to drawings. It shows:

• Fig. 1 shows a two-bath processing device with tubular porous rollers arranged in between, which touch a sheet or strip-shaped material on both sides.
• Fig. 2 shows a processing device according to Fig. 1 in which a sheet or band-shaped material wraps around the porous tubular rollers.
• Fig. 3 shows a processing device according to Fig. 1, in which the porous tubular rollers are integrated in the processing device.
• _F ig. 4 tubular porous rollers that are pivoted.

In Fig. 1, a processing device for treating a sheet or tape-shaped material 1 in two processing containers I, II with two treatment liquids 2, 3 is shown. Likewise, one or a plurality of processing containers can be used, depending on which process the material 1 is subjected to that should. The treatment liquids 2, 3 can be liquids which act chemically on the material 1 or water baths without chemicals, which are arranged one after the other in the desired order. The sheet-like or ribbon-shaped material 1, made of metal, plastic, paper, textile or other fabrics, is fed to the processing container I, undergoes a first treatment, is passed into the second processing container II and so on until the treatments have been completed. In order to reduce carry-over of chemical solutions from one bath to the next, here for example from container I to container II, two tubular porous rollers 4 are arranged one above the other and resiliently between the containers I and II, between which the sheet-like or strip-like material 1 is carried out . The rollers 4 are rotatably supported and are driven, for example, by a spur gear 5. The spur gear 5 is driven in common with the other transport rollers, which are arranged on a plate 6, jointly and synchronously by a motor, not shown, in such a way that the peripheral speed corresponds to the material speed.

The tubular rollers 4 consist of a porous material, for example sintered plastic such as polyethylene or a corrosion-resistant cemented carbide and are superimposed so that both sides of the sheet-like material 1 are always in contact with the rollers 4 by gravity or spring force. The rollers 4 are connected (not shown) at least on one of their end faces to a vacuum generator, for example to a vacuum pump or suction jet pump, so that a vacuum is created in the interior of the tubular rollers 4, as a result of which the treatment liquid 2 located on the strip-shaped material enters the interior of the Rolls 4 is suctioned off. A separator of conventional design is arranged between the rollers 4 and the vacuum generator or behind the vacuum generator, in which the extracted treatment liquid 2 is collected and pumped back into the processing container I, for example with a pump. The performance of the vacuum generator is determined by the working width of the processing machine. Preferably, a partial vacuum is used, the _abs means of compressed air of 2 bar injector as a negative pressure of ^0, 8 _bar. up to 0.9 bar _abs. delivers. The vacuum can also be about 0.5 to 0.6 bar _abs. be.

The pore size of the tubular rollers 4 can be selected within certain limits, since e.g. tubular rollers 4 made of polyethylene are sintered in a mold, pore sizes from 50 μm to 300 μm being able to be produced from the granulate. Sufficient and advantageous because of the lower air consumption are pore sizes from 100 µm to 200 µm, especially since this pore size achieves a smooth surface that is suitable for sensitive materials 1, e.g. for photographic sheet or tape-shaped films or papers are advantageous because of the gentle surface contact.

The porous tubular rollers 4 shown in FIG. 1 can exert pressure on the top and bottom of the material 1 by means of a resilient support, so that they additionally act like squeeze rollers and immediately suck up and remove a liquid bead formed at the inlet of the material 1. The effect of the rollers 4 is that of the nip rollers. Guide devices such as guide plates 7 or separating combs 8 are usually provided on the transport rollers for the automatic introduction of the sheet-like or band-shaped material.

Fig. 2 shows an arrangement with two tubular porous rollers 4 in which the sheet or band-shaped material 1 is guided around the porous rollers 4 with a longer loop through guide plates 7 and separating combs 8. This arrangement acts on the one hand like that described in FIG. 1, but has the advantage due to the long looping of the rollers 4 that the band-shaped material is further dried by the vacuum. In the case of photographic materials which also carry chemical solutions from one treatment bath to the next in their gelatin emulsion layers, the amount of chemical solutions carried away is considerably reduced in this arrangement.

FIG. 3 shows an advantageous arrangement of the porous tubular rollers 4 in a treatment device. Here, the ones usually provided in a developing machine were provided in a simple manner Transport rollers on the plates 6 at the outlet of the first and second processing containers I, II are replaced by porous tubular rollers 4 and these are connected to a vacuum generating device with a separator. Corresponding baffles or separating combs can also be used to wrap the rollers 4 according to FIG. 2.

For processing sheet-like materials in processing baths, these can be attached to one another by means of adhesive strips or clips that do not thicken too much to form a tape-like material 1 and can be processed like a tape. While here adhesive spots are also sucked off with adhesive tapes and freed from the chemical solution, thickening of the tape generated by staples briefly separates the rollers 4 from one another, so that the suction quality is poorer at these points, e.g. Rollers 4 of sintered metal can be used. In this case, porous rollers 4 are advantageous, which are made of a soft, also porous material, e.g. are covered with a sponge or foam-like material into which the thickenings can penetrate.

In Fig. 4, the porous tubular rollers 4 are pivotally mounted on levers 9 about axes 11 (double arrows). This embodiment is suitable for sheet-like or sheet-like materials 1 that are clamped in frames 10 or with a clamping device 10 are connected. When the thickening passes through the frame 10, the rollers 4 are spread and roll away over the thickening, so that only a small amount of processing liquid is carried over. The rollers 4 are pivoted back to their starting position by springs (not shown) after passing through the thickening.

example

At the outlet of a processing machine for photographic materials, the photographic papers discharged from the last washing bath were treated untreated, after treatment with previously known methods and after treatment in a device according to the invention for the amount of water which they carried away from the washing bath.

• 1. Das unbehandelte Photopapier verschleppte aus dem Wässerungsbad pro m² zwischen 73 und 90 g Wasser. Es wurde aus einer Versuchsserie ein Mittelwert von 81,96 g/m² ermittelt und gleich 100 % gesetzt.
• 2. Wurde das Photopapier zwischen zwei Walzenpaaren zwischen Gummilippen hindurchgeführt, so reduzierte sich die verschleppte Wassermenge auf 33,5 bis 47,4 g/m² mit einem Mittelwert von 43,2 g/m² entsprechend 52,7 %. Als nachteilig zeigte sich, daß die Gummilippen bei längerem Gebrauch aufquellen und dadurch leicht wellig werden, wodurch auf dem Papier Streifen mit mehr oder weniger Wasser entstehen. Verunreinigungen im Wasser setzen sich zwischen den Lippen und in dem Lippenmaterial fest und führen zu Verkratzungen der Oberfläche.
• 3. Das Photopapier wurde zwischen zwei Abquetschwalzen, deren Oberfläche mit einem Gummi überzogen war, hindurchgeführt. Die Walzen wurden mit einer Umfangsgeschwindigkeit angetrieben, die der Papiergeschwindigkeit am Austritt aus dem Wasserbad entsprach und das abgequetschte Wasser abgeführt. Die verschleppte Wassermenge betrug zwischen 30,24 und 31,73 g/m² Photopapier mit einem Mittelwert von 30,99 g/m² entsprechend 37,8 % der Gesamtwassermenge.
• 4. Statt der Abquetschwalzen wurden zwei rohrförmige poröse Walzen aus gesintertem Polyethylen eingebaut. Die Rohdurchmesser betrugen bei der unteren Walze 30 mm außen und 21 mm innen und bei der oberen 18 mm außen und 10 mm innen. Die Porenweite betrug nach Angabe des Herstellers 200 µm. Die beiden Walzen waren stirnseitig an eine Strahlpumpe angeschlossen, die mit Preßluft von 2 bar betrieben wurde. Der Unterdruck in den Walzen war mit einem Drosselventil zwischen 0,5 und 0,6 bar _abs. einstellbar. Bei 0,6 bar_abs. betrug die verschleppte Wassermenge nur 24 g/m und bei 0,5 bar_abs. sogar nur 21,5 g/m entsprechend 29,2 % bzw. 26,2 %. Es ge-- lang also mit der erfindungsgemäßen Vorrichtung in einer versuchsmäßigen Ausführung das verschleppte. Wasser auf fast ein Viertel der ursprünglichen Menge zu reduzieren, wobei durch eine Optimierung oder durch ein Herumführen des Photopapieres um die Walzen ohne weiteres eine weitere Reduzierung der Wassermenge möglich ist.

The amount of water carried over was determined both by weighing and with microwave devices and showed almost identical measurement results in grams of water per m ^{2 of} photo paper. The following values were shown:

• 1. The untreated photo paper carried between 73 and 90 g of water per m ² from the washing bath. An average value of 81.96 g / m ^{2 was} determined from a test series and set equal to 100%.
• 2. If the photo paper was passed between two pairs of rollers between rubber lips, the amount of water carried over was reduced to 33.5 to 47.4 g / m ² with an average value of 43.2 g / m ^2, corresponding to 52.7%. It was found to be disadvantageous that the rubber lips swell with prolonged use and thus become slightly wavy, as a result of which streaks with more or less water form on the paper. Impurities in the water settle between the lips and in the lip material and lead to scratches on the surface.
• 3. The photo paper was placed between two squeeze rollers, the surface of which was covered with a rubber. The rollers were driven at a peripheral speed which corresponded to the paper speed at the exit from the water bath and the squeezed water was removed. The amount of water carried over was between 30.24 and 31.73 g / m ^{2 of} photo paper with an average value of 30.99 g / m ^2, corresponding to 37.8% of the total amount of water.
• 4. Instead of the squeeze rolls, two tubular porous rolls made of sintered polyethylene were installed. The raw diameters for the lower roller were 30 mm outside and 21 mm inside and for the upper 18 mm outside and 10 mm inside. According to the manufacturer, the pore size was 200 µm. The two rollers were connected at the end to a jet pump, which was operated with compressed air at 2 bar. The vacuum in the rollers was between 0.5 and 0.6 bar _abs with a throttle valve. adjustable. At 0.6 bar _abs. the amount of water carried was only 24 g / m and at 0.5 bar _abs. even only 21.5 g / m corresponding to 29.2% and 26.2%. So it was possible with the device according to the invention in an experimental embodiment. To reduce water to almost a quarter of the original amount, whereby by optimizing or by moving the photo paper around the rollers, a further reduction in the amount of water is possible.

Claims (8)

1. Device for reducing the carry-over of treatment fluids by sheet or strip materials in their chemical treatment in processing baths, characterized in that behind and / or above the treatment bath (2, 3) two tubular rollers (4) made of a porous material transversely to Direction of travel of the sheet or strip-shaped materials (1) are arranged such that the tubular rollers (4) are connected at the end to a vacuum generator and a separator for the treatment liquid (2, 3) and that the sheet or strip-shaped materials (1) can be guided in this way are that their top and bottom each touch or loop around a porous tubular roller (4) for suction of the treatment liquid (2, 3). 2. Apparatus according to claim 1, characterized in that a tubular porous and underpressure pair of rollers (4) for processing photo materials (1) in roller developing machines at least before a transition of the photo material (1) from a treatment bath (I) in a next one (II) and / or behind the last treatment bath (II) is arranged in such a way that each side of the photographic material (1) comes into contact with a porous, tubular roller (4) or partially encloses one roller (4). 3. Apparatus according to claim 1 and 2, characterized in that the porous material of the tubular rollers (4) consists of a sintered plastic and has pore sizes from 50 gm to 200 microns, preferably 100 microns to 200 microns. 4. The device according to claim 3, characterized in that the tubular rollers (4) are provided on the inside with a support core made of a corrosion-resistant metal, preferably stainless steel. 5. Apparatus according to claim 1 and 2, characterized in that the porous material of the tubular rollers (4) is a corrosion-resistant cemented carbide and has pores in a size of 50 to 200 microns, preferably from 100 to 200 microns. 6. The device according to claim 1 and 2, characterized in that at least one of the tubular rollers (4) can be driven. 7. The device according to claim 2, characterized in that the tubular rollers (4) are part of a roller transport developing machine for photographic materials (1) and as the last pair of rollers at the outlet of the photographic material (1) from a processing tank (I, II) are arranged above the surface of the treatment liquid (2, 3). 8. Apparatus according to claim 1 and 2, characterized in that the tubular rollers (4) of the pair of rollers on levers (5) are rotatably mounted and when passing through holding or clamping devices (10) between the rollers (4) at a distance from each other are spreadable.

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