WO1999037844A1

WO1999037844A1 - Process and installation for washing and for operations of wet treatment of textiles

Info

Publication number: WO1999037844A1
Application number: PCT/IT1999/000011
Authority: WO
Inventors: Fabio Fiaschi
Original assignee: Sint S.R.L.; Gianassi, Pierangelo; Sanchini, Stefano
Priority date: 1998-01-27
Filing date: 1999-01-26
Publication date: 1999-07-29
Also published as: ITFI980025A0; AU2544199A; ITFI980025A1

Abstract

In at least one or more vessels (7) for treatment liquid there are provided power generators with ultrasonic transducers (20, 22), capable of emitting ultrasonic waves into the liquid through which passes the fabric (T) to be treated.

Description

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PROCESS AND INSTALLATION FOR WASHING AND FOR OPERATIONS OF WET TREATMENT OF TEXTILES

DESCRIPTION The use of large installations for washing, dyeing and in general for treating textiles, in other words for finishing, and for practically all kinds of wet treatment, is known in the textile industry. The wet treatments (washing or dyeing or other) require, for continuous operation, the successive immersion of a piece of fabric in, and its removal from, a plurality of successive vessels for treatment with detergent solution, for wringing, for washing and other processes. Fabrics are frequently subjected to a series of relatively violent jets of liquid, and the fabrics must be kept substantially under tension along their active path, which causes considerable elongation of the fabrics which ought, in fact, to be assisted to shrink and consequently to be compacted, particularly in the case of woven fabrics, in other words those consisting of a warp and weft. The installations are relatively very large, with high power consumption, and cause considerable problems with their effluent which is also highly polluting; moreover, they require a continuous consumption of water and consequently of polluting effluent.

The invention relates to a process and an installation which make it possible to achieve the results of the present wet treatment systems, particularly those for the washing, dyeing and general treatment of fabrics, while avoiding the present disadvantages and also obtaining further advantages.

In order to provide further advantages with respect to the present installations and to solve the aforesaid problems, the invention proposes a process - for washing and for operations of wet treatment of fabrics - according to which the fabric is subjected, while immersed, to at least one field of ultrasound. The ultrasonic treatment can be applied in combination with the chemical action of washing solutions, and/or in combination with a physical treatment, for example a heat treatment.

The ultrasonic treatment may advantageously be carried out during the - 2 -

continuous passage of the fabric along a guided path, with the fabric immersed in at least one section of its travel.

The ultrasonic emission along the path may be carried out successively on both sides of the fabric, repeatedly if required. The invention also proposes an installation for wet treatment, such as washing and/or dyeing and/or finishing of a fabric, for the application of the aforesaid process, this installation comprising at least one vessel for a treatment liquid. According to the invention, the installation comprises at least one power generator and an ultrasonic transducer capable of emitting ultrasonic waves into the liquid.

The installation may be of the continuously operating type and may comprise means of feeding, guiding and withdrawing the full-width fabric along a path, with the fabric immersed in at least one section of its travel. According to the invention, the installation may include at least one power generator with an ultrasonic transducer capable of emitting ultrasonic waves toward one side of the immersed fabric as it passes. It is possible to provide at least two power generators, each with an ultrasonic transducer, capable of emitting ultrasonic waves toward the two opposite sides of the fabric successively. The means of feeding, guiding and withdrawing the fabric may be operated so that they make the fabric advance in such a way as to avoid tensions in the fabric in the direction of advance.

Ultrasonic generators are already known for other washing installations, used in sectors other than that in which a generator of this type is used according to the invention, for washing and treating fabrics, in other words for wet treatments and dyeing.

The ultrasonic generator according to the invention can be used principally in machines of the continuous cycle type, but also in those of the discontinuous type, for washing in the full-width and/or twisted state, in order to carry out, possibly with a single pass, multiple operations such as those of desizing, shrinking and compacting the fabric. - 3 -

One of the advantages of the invention is that it considerably reduces the consumption of water and chemical products, with a favorable effect on the operating costs and environmental impact, since there is less effluent and therefore less pollution. The ultrasonic generators may be immersed inside the washing vessels or may be applied to the outside of their walls.

The ultrasonic transducer is activated by a generator, which is a set of electrical circuits capable of producipg electrical energy at high frequency. Under the effect of the emissions of the generator, the transducer generates an ultrasonic wave which is propagated in the liquid.

The emission of acoustic pressure waves at the ultrasonic level in the liquid or washing solution creates an infinite quantity of microbubbles, owing to the phenomenon of cavitation.

When the microbubbles implode on the fabric to be washed, which is immersed in the liquid, they return the energy by which they were created, in the form of mechanical energy. This energy, added to any chemical action of the washing solution, enables very efficient washing to be achieved. The mechanical action generated by the impact of the microbubbles penetrates into the structure of the fabric, proceeding to act between the fibers and exacting the impurities by their implosion.

Another advantageous phenomenon of the mechanical action of the microbubbles on the fabric is that it provides a compaction and regularization of the fabric, caused by the tightening of the warp and weft threads.

The following operations can be carried out by full-width treatment: washing, desizing, scouring, bleaching, shrinking and compaction of the fabric, post-printing washing, thermal shock, finishing by absorption of chemical products, neutralizing, burling (an operation for eliminating the residues of carbonized vegetable particles remaining in wool fabrics) and others. The following operations can be carried out by treatment of the fabric in the twisted state: washing, scouring, bleaching and dyeing of fabrics, - 4 -

shrinking treatments, treatments for softening and imparting a special hand to fabrics, washing after printing and/or after dyeing, burling, and others.

The invention will be more clearly understood from the description and the attached drawing, which shows a non-restrictive practical example of the invention. In the drawing,

Figs. 1 to 4 are diagrams demonstrating the application of the process and the construction of simplified installations in which the invention is applied.

In the illustrated examples, a single immersion vessel is used for the sake of simplicity, but clearly the installation may comprise a plurality, although this plurality is limited, of vessels through which the fabric passes successively as it is immersed and emerges in a continuous and generally full-width operation, such as that used in the present washing installations. Identical or equivalent components are indicated in the different figures by the same references, differentiated by "100", "200", "300".

In Fig. 1 , the number 1 indicates the feeding of the fabric T which is diverted downward by a pass roller 5 so that it is immersed in a vessel 7, from the bottom of which the fabric is diverted by a cylinder 9 so that it re-emerges and is diverted by a subsequent cylinder 11 toward a group of wringing cylinders 13; the numbers 15 and 17 indicate jets of liquid which may strike the fabric for washing and for other functions.

Characteristically, the vessel 7 is provided with ultrasonic generators indicated by 20 and 22, which in this case are applied to opposite walls of the vessel so that they face the fabric T over portions of the descent into and ascent from the vessel. The ultrasonic generators have their electrical parts outside said walls of the vessel, and emit ultrasonic vibrations through said walls of the vessel until they reach the fabric as it runs, in one case, between the cylinders 5 and 9 and, in the other case, between the cylinders 9 and 11 ; in this arrangement, the ultrasonic waves strike the fabric in succession on the same face, in other words on the same side. The fabric can thus be subjected to the ultrasonic treatment, in addition to any necessary - 5 -

conventional washing treatment, since the liquid which acts as the ultrasound transmission medium can also be a liquid with detergent chemical characteristics, and consequently the fabric can also be subjected to conventional washing in the path described above. Any jets 15 and 17 which are present can assist in the action on the fabric. In a following vessel, it is possible to subject the fabric once again to an ultrasonic treatment and to a physical washing treatment to remove residual particles which have been separated from the fabric by the action of the ultrasound.

In Fig. 2, the only variation consists in the arrangement of a single or double unit 120 for the generation of ultrasound, immersed inside the vessel and consequently enclosed between the two descending and ascending runs of the fabric, which is guided inside the vessel between the cylinders 105, 109 and 111.

Fig. 3 shows an arrangement in which a vessel 207 is larger than the vessel 7 and has immersed inside it two ultrasonic generator units 220 and 222 which act on the inner face on the path of the fabric, respectively, between the intermediate cylinders 205 and 209 and between a further intermediate cylinder 210, immersed with the cylinder 209, and the intermediate cylinder 211. In the portion between the two intermediate cylinders 209 and 210 (which are immersed at the bottom of the vessel), a further ultrasonic generator 224 is fitted, and in the drawing this is positioned in the bottom wall of the vessel so that it emits ultrasound into the portion of the fabric between the two cylinders 209 and 210, and consequently onto the side of the fabric opposite that struck by the ultrasound from the two generator units 220 and 222. In this case, the fabric is struck, in succession, by the ultrasound emitted by the ultrasonic generator 220, then by the ultrasound emitted by the ultrasonic generator 224, and then again by the ultrasound emitted by the ultrasonic generator 222.

In the schematic solution shown in Fig. 4, the vessel 307 (equivalent to the vessel 7) has an ultrasonic generator unit 320 which is immersed in the vessel and acts on one of the two sides of the portion of the fabric between - 6 -

the cylinders 305 and 309, while in the portion between the intermediate cylinders 309 and 311 the fabric ascending in the vessel is struck by the ultrasound emitted by the ultrasonic generator 322, which may be immersed in the vessel or may be combined with the adjacent wall of the vessel, and which acts on the side of the fabric opposite that on which the ultrasound emitted by the generator 320 acts.

The arrangements of an installation may also be modified with respect to those in the examples disclosed above, and may also be multiple, in the sense of comprising a plurality of successive vessels. In any case, the arrangement is such that a considerable reduction in overall dimensions is possible, by comparison with what is found in conventional installations; a path with a relatively high intensity of processing may also be provided. In particular, it is possible to operate the installation by controlling the running of the fabric - particularly of full-width fabric - through the installation, without - imposing longitudinal tension and other tension, including transverse tension, on the fabric, while gaining advantages in the washing treatment. This can yield a further advantage in the treatment of the fabric, which in these conditions can be compacted to a greater extent than in conventional installations. The effect of compaction is even more evident in relation to the width, where a decrease in width is added to a tightening of the threads, as was demonstrated in trials which were carried out.

It is to be understood that the drawing shows only an example provided solely as a practical demonstration of the invention, and that this invention may be varied in its forms and arrangements without departure from the guiding concept of the invention.

Claims

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CLAIMS 1. A process for washing and for operations of wet treatment of fabrics, characterized in that the fabric is subjected, while immersed, to at least one field of ultrasound.

2. The process as claimed in claim 1 , characterized in that the ultrasonic treatment is carried out in combination with a chemical action using solutions.

3. The process as claimed, in claim 1 or 2, characterized in that the ultrasonic treatment is carried out in combination with a physical treatment, particularly with water or solution at a temperature higher than the ambient temperature.

4. The process as claimed in claim 1 and/or 2 and/or 3, characterized in that the ultrasonic treatment is carried out during the continuous passage of the fabric along a guided path, with the fabric immersed for at least one section of its travel.

5. The process as claimed in claim 4, characterized in that the ultrasonic emission along the path is carried out successively on both sides of the fabric.

6. An installation for washing and/or dyeing (and/or wet treatment of a fabric), for the application of the process as claimed in at least one of the preceding claims, comprising at least one vessel for a treatment liquid, characterized in that it comprises a power generator with an ultrasonic transducer capable of emitting ultrasonic waves into the liquid.

7. The installation as claimed in claim 6, comprising means of feeding, guiding and withdrawing the full-width fabric along a path which comprises at least one section in which the fabric is immersed, characterized in that it comprises at least one power generator with an ultrasonic transducer capable of emitting ultrasonic waves into the liquid toward one side of the immersed fabric.

8. The installation as claimed in claim 7, characterized in that it comprises at least two power generators, each with an ultrasonic transducer, - 8 -

capable of emitting ultrasonic waves toward the two opposite sides of the fabric successively.

9. The installation as claimed in claim 7 or 8, characterized in that the means of feeding, guiding and withdrawing the fabric are operated so that they make the fabric advance in such a way as to limit tensions in the fabric in the direction of advance.

10. A process and installation for washing and for operations of wet treatment of fabrics, the whole as described above and as represented by way of example in the attached drawing.