GB2076031A - Calender-finishing cotton cloth - Google Patents

Abstract

Woven or knitted cotton cloth 10 is subject to calendar-finishing by being fed continuously through a pressure steamer 1. The cloth follows a zig-zag path through the steamer by rolls 6 and 7, and after entering the steamer the cloth 10 is soaked with hot water in tank 8. Thereafter, the cloth is steamed in the steamer body, so as to swell the fibres constituting the yarns of the cloth, and to set the arrangement thereof to lie in a certain direction. <IMAGE>

Description

SPECIFICATION Caiender-finishing a cloth.

This invention relates to a method for the continuous calender-finishing of a long woven or knitted cloth containing or composed of cotton fibres.

To caiender a cloth, conventionally a pretreated cloth has been mercerized as a secondary process, in order to render glossy the surface of the cloth.

In such a conventional calender-finishing -- i.e., mercerization -- a plurality of steps are needed, such as the application of a caustic alkali solution to the cloth to be calendered, and the application of tension to the cloth soaked with the caustic alkali solution, so that a long time is needed to complete the treatment.

Moreover, the apparatus which must be provided to perform each of the process steps must be relatively large. In particular a tenter has to be provided to apply the tension to the cloth, and this uneconomically takes up much space, so that the installation cost of the apparatus unavoidably becomes most considerable. The application of conventional mercerization-finishing also has been limited to woven cloths only, and it has hardly been possible to render glossy the surface of a knitted cloth.

In view of the foregoing, it is a principal aim of this invention to offer an excellent method for the continuous calender-finishing of a cloth without the need to apply a caustic alkali solution nor tension cloth.

Accordingly, this invention provides a method for the continuous calender-finishing of a woven or knitted cloth composed of or containing cotton fibres,in which method the cloth is fed continuously into, through and out of a high pressure steamer the interior of which is maintained at conditions of high temperature wet heat under an elevated pressure, the cloth is soaked with a sufficient amount of hot water after entering the steamer body, and the cloth is then steamed by the high temperature and high pressure wet heat conditions in the steamer body so as to swell the fibres constituting the yarns of the cloth and to set the arrangement thereof.

Preferably, the interior of the steamer is maintained at conditions of saturated water vapour in the range of from 1400 to 1 600C.

By the method of the present invention, it is possible to calender knitted cloth containing or composed of cotton fibres, which otherwise had been considered impossible. Furthermore, since no caustic alkali solution is applied to the cloth, the costs for the agent and the apparatus required to apply the agent can be eliminated, as can the use of a tenter. Thus, the method of this invention can give excellent results and also is economic to perform.

This invention extends to cloth whenever calender-finished by a method of this invention as described above.

In order that this invention may better be understood, one specific example thereof will now be described in detail, reference being made to the accompanying drawings, in which: Figure 1 is an explanatory drawing of an example of apparatus for use in performing the method of this invention; and Figures 2(a) and (b) are enlarged schematic microscopic diagrams of cotton fibres constituting the yarns of a cloth, respectively before and after swelling by the treatment method of the present invention.

Figure 1 shows an example of a high pressure steamer suitable for use in performing the treatment method of this invention, under conditions of thigh temperature and pressure wet heat. A high pressure steam body 1 is provided with a cloth inlet 2 and a cloth outlet 3, respectively provided with an inlet seal mechanism 4 and an outlet seal mechanism 5.

The two seal mechanisms may take any suitable form of construction which allows the cloth to pass continuously therethrough whilst maintaining the high temperature wet heat conditions in the steamer body 1 without substantial leakage. The inlet seal mechanism 4 in this example comprises a pair of rubber seal rolls 41 pressed together to define a nip, a liquid seal tank 42 provided nearer the steamer body interior than the rubber seal rolls 4,, and a pair of squeeze rolls 43. The outlet seal mechanism 5 comprises a pair of rubber seal rolls pressed with each other, 51, and a slow cooling tank 52 provided nearer the steamer body than the rubber seal rolls 51.

A plurality of cloth guide rolls 6 are provided in two series, one above the other, in the steamer body 1 to define a zig-zag path along which the cloth 10 to be treated is transported. At appropriate positions, the lower cloth guide rolls are replaced by tension control rolls 7. A hot water supply tank 8 is provided in the vicinity of the cloth inlet 2 in the steamer body 1, through which hot water may be circulated, maintaining a constant amount in the tank, in order to soak with hot water the cloth fed into the steamer body 1. A preliminary washing tank 9 is provided in the vicinity of the cloth outlet 3 in the steamer body 1, through which hot water may be circulated to maintain a constant amount therein. The preliminary washing tank 9 may be dispensed with, depending upon the circumstances.

Continuous calender-finishing of a long cloth 10, for instance comprising mainly cotton fibres, using this apparatus is performed as follows.

On starting the operation, super-heated steam is supplied to the steamer body 1 in order to obtain within the steamer body conditions of saturated water vapour at a temperature in the range of from 140 to 1 600C. Water is recirculated through the liquid seal tank 42 and the slow cooling tank 53, and hot water is recirculated through the hot water supply tank 8 and the preliminary washing tank 9. It is desirable that the temperature of hot water circulated through the hot water supply tank 8 is sufficiently high, according to the temperature in the steamer body 1, and that the temperature of water in the slow cooling tank 53 is maintained at about 500C.

Then, a cloth 10 to be treated is continuously supplied through the inlet side seal mechanism 4 into the steamer body 1, and is then guided round the first tension control roll 7 and the first cloth guide roll 6 to be fed into the hot water supply tank 8. There, the cloth is sufficiently soaked with hot water, whereafter the cloth is steamed by the high temperature wet heat conditions as the cloth is guided along the zig-zag path defined by the cloth guide rolls 6. Due to the effect of the steaming, the fibres constituting the cloth are swollen sufficiently to render the cloth glossy.

Cotton fibres consituting the yarns of a cloth before swelling are, as shown in Figure 2(a), flat and frequently twisted, but their surfaces are by no means flat, having many holes or creases.

Therefore, the surface of the cloth lacks gloss. In contrast to this, as can be seen from Figure 2(b), cotton fibres once swollen with hot water by the steaming at higher temperatures by the method of this invention remain in an expanded state to be generally circular in cross-section, even after drying, and moreover the fibres become arranged to lie in a certain direction. Therefore, diffused reflections from the fibres are reduced so that the cloth appears to be excellently glossy.

As described above, in the method of this invention a knitted or woven cloth composed of or containing cotton fibres is continuously fed through a high pressure steamer the interior of which is maintained at conditions of a high temperature wet heat under pressure. The cloth initially is soaked with a sufficient amount of hot water after entering the steamer body, whereafter the cloth is steamed by the high temperature wet heat in the steamer body, as the cloth follows the zig-zag path. This causes the fibres constituting the yarns of the cloth to be dilated in cross-section to take up a circular form, and the fibres become arranged to lie in a certain direction. By the method of the present invention, therefore, a cloth can be produced effectively and economically having a deep gloss on the surface thereof, without the need to use such agents as a caustic alkali solution for the treatment.

A particular merit of the present invention is to make possible the calender-finishing of a knitted cloth as in a conventional mercerization process, but without the need to apply tension to the cloth.

Another feature of the invention is to facilitate the economic continuous calender-finishing of a long cloth with the use of a simple apparatus having no such device as a tenter.

Claims (6)

1. A method for the continuous calender- finishing of a woven or knitted cloth composed of or containing cotton fibres, in- which method the cloth is fed continuously into, through and out of a high pressure steamer the interior of which is maintained at conditions of high temperature wet heat under an-elevated pressure, the cloth is soaked with a sufficient amount of hot water after entering the steamer body, and the cloth is then steamed by the high temperature and high pressure wet heat conditions in the steamer body so as to swell the fibres constituting the yarns of the cloth and to set the arrangement thereof.

2. A method according to claim 1, in which the interior of the steamer is maintained at conditions of saturated water vapour in the range of from 140C to 1600C.

3. A method according to claim 1 or claim 2, in which the cloth is subjected to a preliminary washing step prior to leaving the steamer, following the steaming thereof.

4. A method according to any of the preceding claims, in which the cloth is constrained to follow a zig-zag path the runs of which extend generally vertically, as the cloth is advanced through the steamer.

5. A method for the continuous calenderfinishing of a woven or knitted cloth composed of or containing cotton fibres, substantially as hereinbefore described with reference to the accompanying drawings.

6. A woven or knitted cloth composed of or containing cotton fibres whenever calenderfinished by a method according to any one of the preceding claims.