EP0065158B1 - Method and apparatus for washing sheet-like textile materials subsequent to mercerization - Google Patents

Description

The invention relates to a method and a device for washing out lye from sheet-like textile material, a liquor being fed countercurrent to the direction of transport of the sheet-like material and the sheet-like material being passed through pairs of rollers and a liquor supply in such a way that the sheet-like material is repeated in sections of a washing container Immerse the material in the liquor, squeeze it in a nip and then immediately soak it with the liquor.

Such a method and such a device are described in DE-A-1 460 362. The fact that the textile material impregnated with the washing water is repeatedly immersed in the liquor and squeezed out in the nip and then impregnated with the liquor immediately afterwards results in a very good result good washing effect. However, a disadvantage of this known method is that the concentration gradient in each of the sections changes over time in the sense of a deterioration in the washing effect.

DE-U-1 893 511 already describes a method and a device for washing out lye from sheet-like textile material by means of a washing container which is divided into sections by overflow plates and into which several guide rollers for the textile material are immersed one after the other in the guide direction of the web material, for each section at least one guide roller. The wash container liquor is pumped around in each section and fed back to the section in question from above the guide roller. In this case, two spaced guide rollers are immersed in the wash tank fleet in each section. In front of and behind these guide rolls, the textile material is guided vertically over further, higher arranged guide rolls. The fleet is returned to the relevant section via essentially horizontally directed spray pipes which spray from the inside and outside against the vertical web sections. At the exit of each section, the textile goods are passed through a pair of ironing rollers.

This is particularly disadvantageous in that the liquor is squeezed out of the textile material by the pair of ironing rollers, but the textile material is then passed through air, so that it is - at least partially - soaked with air. The textile web is then sprayed with the pumped-over liquor in the next section and is then immersed in the liquor in this section, and so on. The exchange of the liquor is only imperfect, because the textile goods were able to soak up air behind the nip of the ironing rollers and because care was not taken to ensure that this air is squeezed out again when the textile goods are immersed in the liquor. To wash out the liquor in this known method, therefore, either a disproportionate amount of fresh water and / or a very long washing device are required, both of which lead to increased costs.

US-A-3 763 671 describes a method for washing out lye from sheet material with a washing container divided into sections by overflow plates, a guide roller being immersed in each section and being associated with a lay-on roller. Between two adjacent support rollers and the guide roller assigned to them, a receiving space is formed for the liquor that is supplied from above by spray pipes and pumped around in the circuit, but no liquor can accumulate therein, because all the rollers are designed as ribbed rollers, with the combs of adjacent rollers Stand gap. The fleet supplied from the top in the circuit therefore flows through the spaces between the ribs of the rollers. Also, owing to the fin rolls described, squeezing the web material in the nip is not possible and is also not intended. The spaces between the ribs and fin rollers serve only as storage spaces for the fleet.

DL-A-63 454 describes a process for washing out lye from sheet-like textile material, wherein fresh water is fed to a washing container divided into sections with guide rollers and lay-on rollers in countercurrent to the textile material, so that the concentration gradient between the liquor and the textile material remains essentially constant , whereby one regulates the fresh water supply to the washing tank. The fresh water is supplied to the washing tank near its outlet in a regulated quantity and in a flow that is not divided. However, this has the disadvantage that the control does not meet all accuracy requirements, because standard control devices in the range of volume flow to be controlled today do not work with sufficient accuracy.

The invention is therefore based on the object of proposing a method and a device for washing out lye from sheet-like textile goods of the type mentioned at the outset, which is distinguished by a particularly low consumption of fresh water combined with a good washing action.

To achieve this object, the method according to the invention is characterized in that the liquor is pumped around in each section and fed in again from above the pair of rolls assigned to each section, specifically in the liquor supply formed between the pairs of rolls, in that the wash tank is given fresh water in countercurrent to the web-shaped one Well feeds in such a way that the concentration gradient between the liquor and the web-like material remains essentially constant and that an adjustable basic quantity of fresh water is fed to the wash container outlet, and a regulated partial quantity of fresh water is separated from it at a suitable point.

Pumping in addition to the optimized use of water ensures that the liquor is mixed evenly in each section. As a result, the controls are more precise, the dead time is reduced and the control behavior is stabilized. The textile web squeezed in the nip then immediately arrives in the fleet stock formed over these rollers and can thus connect directly Soak squeezing with liquor. These measures result in a very good exchange of the fleet in each section. The invention is therefore particularly suitable for stabilizing mercerized textile goods and is characterized by low fresh water consumption with good washing action. Only the - relatively small - additional amount of fresh water has to be controlled, which can be done with great accuracy using control devices that are commercially available today. These measures therefore also contribute to the lowest possible consumption of fresh water, combined with the lowest possible amount of lye to be removed.

There are several options with regard to the formation of the control loop. A first possibility is characterized in that the fresh water partial quantity is regulated as a function of the weak liquor obtained at the entrance.

A further possibility is characterized in that the fresh water partial quantity is regulated in dependence on the lye which is located on the web-like textile material at the exit. The weak liquor at the inlet of the washing tank no longer falls in in a constant concentration. The residual lye content on the textile is regulated. Subsequent processes in the treatment of the textile goods can e.g. require that the residual alkali content of the textile goods be kept constant, because otherwise process engineering problems can arise.

In a practical embodiment, this is done by continuously measuring the pH of the lye behind the washing container. The pH of the lye can also be measured in one of the last sections of the washing container. Here, one makes use of the fact that a fixed relationship is established between the alkali and the textile goods in the washing liquor, whereby one can then measure the alkali content of the liquor in one of the last sections, which allows the back calculation to the alkali content of the textile goods. The control quantity of fresh water is then applied depending on this measured value.

The device according to the invention for carrying out this method is characterized in that a plurality of guide rollers for the web-shaped textile material are immersed in the washing container, which is divided into sections by overflow plates, to which a front and rear lay-on roller is assigned in such a way that a fleet supply is formed between the rollers Each section is assigned a suitable liquor circuit with circulation pump and spray pipe opening above the relevant guide roller, that a line is provided in the area of the outlet of the washing tank for the supply of an adjustable basic amount of fresh water, that in the area of the inlet of the washing tank there is a line for this Wash liquor to be withdrawn from the wash tank opens and that a further line is provided, via which a controlled amount of fresh water can be fed to the wash tank. Protection without the features of the process claims is also claimed for these measures.

• Fig. 1 - schematisch in einer Seitenansicht die wesentlichen Bauelemente einer Vorrichtung nach der Erfindung;
• Fig. 2 - vergrössert eine Sektion des Waschbehälters nach Fig. 1;
• Fig. 3 - eine Darstellung ähnlich Fig. 2, wobei zusätzlich die im Kreislauf umgepumpte Flotte dieser Sektion dargestellt ist;
• Fig. 4 - ebenfalls schematisch die Regelung der Frischwasserzufuhr bei dem Waschbehälter nach Fig. 1.

The invention is explained in more detail below on the basis of an exemplary embodiment from which further important features result. It shows:

• Fig. 1 - schematically in a side view the essential components of a device according to the invention;
• Fig. 2 - enlarges a section of the washing container according to Fig. 1;
• FIG. 3 - a representation similar to FIG. 2, the fleet of this section pumped around in the circuit also being shown;
• 4 - likewise schematically the regulation of the fresh water supply in the washing container according to FIG. 1.

FIG. 1 schematically shows a washing container 1 which is open at the top and through which web-like textile material to be stabilized is guided from an entrance 2 in the direction of arrow 3 to an outlet 4. The washing container is divided into sections 6 in the transverse direction by overflow plates 5 - see also FIG. 2. In each section, a guide roller 7 dips into the fleet. In front of and behind each guide roller, there is a support roller 8 on it. All rollers have a smooth circumference and are preferably provided with a rubber coating. In particular, FIG. 3 shows that a receiving space for the fleet is therefore formed in the space between the guide roller 7 and the two support rollers 8 assigned to it.

An immersion plate can be provided in front of each guide roller and in front of each overflow plate (see FIG. 2), which plunges into the fleet and which protrudes upwards from the fleet to a noticeable extent. The immersion plate is slightly inclined towards its guide roller 7.

In particular, FIG. 3 shows that the textile fabric web passed through the device is squeezed in the nips between the lower guide roller and the two upper lay-on rollers resting on it. After leaving the rear pinch gaps, the web immediately sucks up with the liquor, which is pumped out of this section in a separate circuit and fed back to this reservoir via a spray tube 12. The spray tube is thus located directly above the reservoir mentioned, as can be seen in FIG. 3.

The circuit for the fleet is each completed by a line 10, via which the water is pumped around with the aid of a pump 11 and possibly an adjustable throttle.

The control scheme according to FIG. 4 shows that a basic amount of fresh water is supplied to the outlet 4 of the washing container 1 via a manual setting 13 in the direction of the arrow 14. A controlled portion of the fresh water is guided in the direction of arrow 15 to the washing tank via a control valve 16 and an inlet pipe 17.

4 shows a control in such a way that the control valve 16 is acted upon in a control circuit 18 by a measuring sensor 19, which measures the amount of weak liquor produced in the direction of arrow 20 and drawn off from the washing container 1. The regulated subset becomes the washing container 1 approximately fed in the front third of the washing container via the inlet pipe 10.

The regulated fresh water partial quantity can, however, also be regulated depending on the alkali which is located on the web-shaped textile material at the exit, i.e. approximately at the height of arrow 4 of FIG. 4. The pH of the lye behind the washing container can then be measured continuously or in one of the last sections of the washing container. In this procedure, the inlet 17 for the regulated fresh water portion is preferably in the last third of the washing tank 1. It is important for this that the distance between the measuring point and the control point is kept as short as possible due to the inertia of the control. This also applies to the control according to FIG. 4, where the feed pipe, as mentioned, is preferably located above the front third of the washing container.

Claims (6)

1. A process for washing lye from sheet-like textile material, in which liquor is passed in contra-flow to the direction of transport of the sheet-like material and the sheet-like material is then led through pairs of rolls (7, 8) and a liquor supply, in a manner such that the sheet-like material is repeatedly submerged in the liquor in sections (6) of a washing tank (1), squeezed in a roll nip and immediately thereafter impregnated with the liquor, characterised in that the liquor in each section (6) is pumped round and reintroduced from above the pairs of rolls (7, 8) of each section, i.e. into the liquor supply formed between the pairs of rolls (7, 8), in that fresh water is led into the washing tank (1) in contra-flow to the sheet-like material in a manner such that the fall in concentration between the liquor and the sheet-like material remains substantially constant, and in that a controllable amount of fresh water is added at the outlet of the washing tank (1), and also a regulated proportion of fresh water is separated therefrom at a suitable point.

2. Process according to claim 1, characterised in that the fresh water proportion is regulated in relation to the consequentially weakened lye at the inlet.

3. Process according to claim 1, characterised in that the fresh water proportion is regulated in relation to the lye which is present on the sheet-like textile material at the outlet.

4. Process according to claim 3, characterised in that the pH value of the lye is continuously measured beyond the washing tank (1).

5. Process according to claim 3, characterised in that the pH value of the lye is measured in the last of the sections (6) of the washing tank (1).

6. Apparatus for carrying out the process according to one of claims 1 to 5, characterised in that a succession of a plurality of leading rolls (7) for the sheet-like textile material dip into the washing tank (1) which is divided into sections (6) by overflow plates (5), and in each case a forward and backward bearing roll (8, 8) are positioned in a manner such that a liquor supply is formed between the rolls (8, 7, 8), in that each section (6) is in a liquor circuit with a circulation pump (11) and having a spray pipe (12) above the appropriate leading roll (7), in that a conduit for the addition of a controllable amount of fresh water is provided in the region of the outlet (4) of the washing tank (1), in that a conduit for the washing lye to be removed from the washing tank (1) opens in the region of the inlet of the washing tank (1), and in that a further conduit is provided through which a regulated amount of fresh water can be introduced into the washing tank (1).

Images