GB2084049A - Pre-decatizing cloth - Google Patents

Abstract

Cloth containing wool is treated with predecatizing liquid (4) by means of a rotary coating roller (2) partially immersed in bath (5) thereof, rollers (6, 6a) guide the cloth web (1) into contact with an upper portion of the roller (2). Sensors (7, 7a, and 8, 8a) act to sense the change in the moisture content of the web (1) as a result of said coating and a controller (9) responds to any departure in the sensed change from a desired change (10) to vary the amount of liquid (4) applied to the web (1). This is achieved by varying the area of contact between the roller (2) and the web (1) and/or the depth of immersion of the roller (2) in the bath (5). <IMAGE>

Description

SPECIFICATION Preadecatizing methods and apparatus The invention relates to pre-decatizing methods and apparatus.

Hitherto chemical decatizing has been generally only carried out in a discontinuous manner in a luster shrinking and winding machine for example.

This known method and apparatus has a number of disadvantages. The material to be decatized is treated initially with sodium disulphide and then wound in an almost wet condition togetherwith a follower web of satin, molten or the like, on the decatizing cylinder of the luster shrinking or finish decatizing machine. In this machine the cloth is subjected over a relatively long time period to a steam or suction treatment.

The problems and disadvantages which thereby arise, stem from the fact that the follower webs become increasingly damp and after a few treatment batches must be withdrawn from the decatizing machine and subjected to a separate driving process. This manner of operation is not only inconvenient and time consuming but the chemicals act to substantially shorten the useful working life of these follower webs which are quite costly.

German Patent Specification 2218671 discloses the use of appropriate chemicals to achieve desired decatizing effects as a continuous process. The chemicals are applied directly onto the clotch before decatizing. In order to achieve an effective and particularly uniform effect, a substantial quantity of chemicals must be applied uniformly to the material to be decatized during a relatively high rate of passage. In practice this problem has not been satisfactorily solved. Thus for example in one proposed method the chemicals have been sprayed on the cloth but this produced spotting and striping and so the decatizing effect was unsatisfactory. An additional distribution resulted in no appreciable improvement in the moisture values.

Further proposals include the injection of the chemicals with steam. In this way chemicals have been supplied by injection methods in steam to bring the material to be decatized into contact with the mixture formed during the decatizing process, however, poor operational efficiency was achieved.

In the impregnation method, a textile material is brought into contact during the impregnation with a relatively large quantity of the mixture. An intermediate carrier is used for concentrating the treatment mixture, which is then brought into contact with the textile material along a contact path by contact pressure. An endless follower acting as the intermediate carrier is provided with the treatment mixture then passed over a contact path against the textile material to be treated and subsequently is separated from the textile material. The intermediate carrier is thus subjected to the treatment mixture outside the contact path. This method has also failed to give satisfactory results in practice. Primarily operational disadvantages have arisen. The continual contact with the chemicals leads to an accelerated wear of the material of the interemediate carrier.Because the intermediate carrier is in the form of an endless loop substantial problems also arise in exchanging and/or renewing the carrier. The integrated construction of such machines and devices requiring the fitting of an endless follower leads not only to high costs, but also to lengthy gaps in production.

Together with these inefficiencies there also arises the disadvantage of a non-uniform decatizing effect, resulting from the method of application. The absorption capabilities of the intermediate carrier become uncontrollable particularly with increasing charging time, as a result of which constant decatizing effects become questionable.

Because of the cost and the technical disadvantages of the so-called "excess impregnation methods" there have been proposed so-called "minimal application methods" in which it is sought to apply only so much treatment mixture to the material to be decatized as is necessary for the achievement of the desired effect.

According to the invention, there is provided a predecatizing treatment method for the continuous predecatizing treatment of a cloth web consisting at least partially of wool with a predecatizing liquid comprising the steps of passing the web into contact with a liquid applicator to receive a uniform coating of the liquid, measuring the amount of liquid acquired by the cloth and varying the amount of liquid dispersed by the applicator in a sense to maintain the amount of liquid acquired by the cloth substantially constant.

According to the invention, there is further provided predecatizing treatment apparatus comprising a bath for containing a predecatizing treatment mixture a rotary coating roller arranged to be partially immersed in the mixture when in the bath, and means for guiding a web to be impregnated with the mixture along a path into contact with the roller to receive said mixture from the roller.

According to the invention, there is still further provided predecatizing treatment apparatus comprising a bath containing a predecatizing treatment liquid, a rotary coating roller partially immersed in the bath of predecatizing treatment liquid, guide means for guiding a web at least partially of wool into contact with an upper portion of the roller whereby as the web is displaced and the roller rotated the web is uniformly coated with liquid by the roller, means for sensing the change in moisture content of the web as a result of said coating and means reponsive to any departure in the said change from a desired change to vary the area of contact between the roller and the web and/or the depth of immersion of the roller in the bath, in a sense to bring the measured change into line with the desired change.

Predecatizing treatment methods and predecatizing treatment apparatus all embodying the invention will now be described, by way of example with reference to the accompanying diagrammatic drawings in which: Figure 1 is a side elevation of a predecatizing treatment apparatus for single sided treatment of cloth; Figure la is a side elevation of another predecatiz ing treatment apparatus for double sided treatment of cloth; Figure 2 is a side elevation of predecatizing treatment apparatus in conjunction with decatizing apparatus; and Figure 3 is a side elevation of predecatizing treatment apparatus in conjunction with apparatus for continuous pressing and fixing.

The predecatizing treatment apparatus shown in Figure 1 is for single sided treatment of cloth consisting at least partially of wool while the predecatizing apparatus shown in Figure 1a is for double sided treatment of cloth.

In each of Figures 1 and lathe parts of the apparatus for treating the first side of the cloth are similar and so are similarly referenced. In Figure la the parts of the apparatus for treating the second side of the cloth are similar to the parts for treating the first side and so have similar references but with the adjuct "a".

Since the processes involved in Figures 1 and la are generally. the same they will be described together.

As shown in both Figures 1 and 1a a length of cloth 1 is impreganted with a chemical mixture 4,4a by means of a rotating coating roller 2, 2a immediately before entry into a decatizng machine 3. Since decatizing mixtures are well known, details of particular chemical compositions are not given here.

The rotary coating roller 2, 2a is partially submerged in the mixture 4,4a held in a container 5,5a and upon rotation, the roller 2, 2a transfers the mixture to the upper surface of the cloth 1. Guide rollers 6, 6a, 12, 12a guide the cloth both upstream and downstream of the coating roller 2,2a. The guide rollers are mounted on adjustable supports (not shown) so that their height is adjustable to vary the area over which the cloth 1 and coating roller 2, 2a make contact. The container 5, 5a holding the mixture 4, 4a is mounted on an adjustable support (not shown) so that its height is also adjustable to vary the depth to which the coating roller 2, 2a is immersed. Motor means (not shown) are coupled to the guide roller supports and to the container support and are energisable to raise or lower the supports.

Sensors 7, 7a and 8,8a are respectively located upstream and downstream of the guide rollers 6,6a, 12, 1 2a and are arranged to measure the mdisture content and/or the density of the cloth 1 before and after treatment with the mixture. In the case of Figure 1a only three sets of sensors 7,7a, 8, 8a and 11, liy are provided to measure the moisture content, one before treatment of the cloth, another after treatment of the first side and the last after the treatment of both sides. The signals generated by the sensors are fed to a controller 9.

The controller 9 is also responsive to the setting of a desired value input 10, 10a representing a desired level of moisture content or density of the cloth and produces a control signal for the motor means (not shown) to adjust the immersion depth of the coating roller 1 in the mixture 4, 4a and/or the area of contact between the cloth and the coating roller 2, 2a in a sense to cause the measured levels of the sensor 8,8a, 11, 1 la to equal the values of the desired value input 10, 1 0a. Each sensor can take the form of a density measuring device, a thickness measuring device, electronic moisture measuring apparatus or a radiation detector for example.

The described predecatizing treatment apparatus' is incorporated directly upstream of a treatment machine in the form of a pressing and fixing machine 3a as shown in Figure 3 and/or a continuous decatizing machine 3 as shown in Figure 2 so that the chemical impregnation material can be brought into action directly in response to mechanical surface pressure, and temperature and humidity imposed on the material to be treated. By these measures favourable operational efficiency is achieved; moreover vapourisation effects and losses of moisture are reduced to a minimum.

The method and apparatus described do not require an intermediate carrier to achieve a uniform and excess free application of the mixture to the cloth to be treated.

The material to be decatized is instread subjected directly before the decatizing treatment to a simple and safe mixture coating. With the aid of the measurement and control method an adjustable and continuously controllable minimal application without excess of mixture becomes possible. By continual measurement of the moisture content before and after the mixture coating, the results are continuously measured, compared with the input value and correspondingly automatically adjusted to the predetermined desired value.

The economy of this coating method is based on the controlled coating with the mixture. Under these conditions the thus treated cloth is directly subjected to a decatizing treatment and/or a pressing and fixing treatment.

By chemical action the deformation temperature of the wool keratin in the cloth is reduced and decatizing effects are achieved even at relatively low steam temperatures.

Furthermore, the chemical decatizing leads to a remarkable permanence in the fixing of the effect appearance. Tests indicate that the best results arise with a coating quantity of between 18 and 35% related to the weight of the cloth. Anionic and cationictensilestogetherwith alcohol are suitable as additions to the water used for carrying out the method.

The described method is economical and produces greater uniformity in appearance of the decatized cloth.

With previously proposed discontinuous boiler decatizing in which permanent decatizing effect is produced by the treatment of a web and a follower wound within an autoclave, different effects often arise in the cloth between the commencement and completion of the winding.

Claims (12)

1. A predecatizing treatment method for the continuous predecatizing treatment of a cloth web consisting at least partially of wool with a predecatizing liquid comprising the steps of passing the web into contact with a liquid applicator to receive a uniform coating of the liquid, measuring the amount of liquid acquired by the cloth and varying the amount of liquid dispensed by the applicator in a sense to maintain the amount of liquid acquired by the cloth substantially constant.

2. Predecatizing treatment apparatus comprising a bath for containing a predecatizing treatment mixture, a rotary coating roller arranged to be partially immersed in the mixture when in the bath, and means for guiding a web to be impregnated with the mixture along a path into contact with the roller to receive said mixture from the roller.

3. Apparatus according to claim 2, including sensors mounted along the said path both upstream and downstream of the coating roller to provide an indication of the mixture content acquired by the web from the roller and a controller for comparing the acquired mixture content with a desired mixture content.

4. Apparatus according to claim 3, wherein the controller is arranged to vary the immersion depth of the coating roller in the bath and/or the area of contact between the cloth and the coating roller in a sense to maintain the results of the comparison constant.

5. Apparatus according to any one of claims 2 to 4, wherein the guide means includes guide rollers for guiding the web, the guide rollers being adjustable in a direction at right angles to the plane of the adjacent web to vary the area of contact between the web and the coating roller.

6. Apparatus according to any one of claims 2 to 5, wherein each sensor is arranged to sense the moisture content of the web.

7. Predecatizing treatment apparatus comprising a bath containing a predecatizing treatment liquid, a rotary coating roller partially immersed in the bath of predecatizing treatment liquid, guide means for guiding a web at least partially of wool into contact with an upper portion of the roller whereby as the web is displaced and the roller rotated the web is uniformly coated with liquid by the roller, means for sensing the change in the moisture content of the web as a result of said coating and means responsive to any departure in the said change from a desired change to vary the area of contact between the roller and the web and/or the depth of immersion of the roller in the bath in a sense to bring the measured change into line with the desired change.

8. A predecatizing treatment method substantially as hereinbefore described with reference to the accompanying drawings.

9. Predecatizing treatment apparatus substantially as hereinbefore described with reference to Figure 1 of the accompanying drawings.

10. Predecatizing treatment apparatus substantially as hereinbefore described with reference to Figure la of the accompanying drawings.

11. Predecatizing treatment apparatus substantially as hereinbefore described with reference to Figure 2 of the accompanying drawings.

12. Predecatizing treatment apparatus substantially as hereinbefore described with reference to Figure 3 of the accompanying drawings.