GB2038242A - Apparatus for space dyeing of yarns - Google Patents

Abstract

A bank of side-by-side yarns 18 are space dyed by a matrix of pads, the pads being arranged to travel in an endless path and each being supplied with a dyestuff in accordance with a predetermined pattern from multicolour dispensing heads at a location 34 spaced from the location where the pads are pressed to the yarns. All of the dyeing takes place along a pressure line defined by two nip rollers 20,22 and therefore it is easier to keep the space dyeing in register as between all the yarns in the yarn bank. The pads are preferably located in pockets on an endless belt 24 and co-operate with solid projection on roller 22. <IMAGE>

Description

SPECIFICATION Improvements relating to the space dyeing of yarns This invention relates to the space dyeing of yarns so that individual lengths of the same yarn may be coloured differently. In practice, the aim is to space dye a whole bank of yarns disposed side by side, so that said yarns can subsequently be tufted or otherwise be formed into loops in a fabric, such as a carpet fabric, to form the pile of the fabric, the coloured length of the yarns forming the loops of the pile so that the colour pattern in which the yarns are dyed appears, albeit foreshortened by the looping of the yarns, in the pile of the finished fabric.

The desireability of space dyeing yarns for the formation of colour patterned pile fabrics is well known.

Conventionally intricately coloured carpet fabrics such as Axminster and Wilton are produced by a process involving the drawing of individual, single coloured yarns, and either weaving the yarns into the fabric in a pattern controlled by a complicated control mechanism known as a Jacquard or by providing a spool of yarns for each row of tufts in the fabric pattern. The process is expensive and can be troublesome as to equipment is complicated.

Many attempts have been made to provide for the production of patterned pile fabrics without the need to use Axminster or Wilton weaving methods. These attempts include silk screen printing a self coloured tufted fabric by passing it through a number of rotary silk screen printing stations each arranged to print a different colour of the pattern, and also transfer printing the fabric by a process involving the application of heat to a transfer sheet which is printed in the pattern to appear on the fabric, in inks containing sublimable dyestuff.

The heat releases the dyestuff in the form of a vapour which deposits in the pile of the tufted fabric in the pattern in which it appeared on the transfer sheet. The silk screening method has the advantage over the transfer printing method that penetration of the dyestuff into the pile is better, but the transfer printing method.has the advantage that there is no liquid involved in the transfer printing step, and the whole pattern can be applied to the fabric in a single printing operation. The transfer printing process is limited in addition in that at present sublimable dyes will deposit satisfactqrily only on synthetic fibres and filaments, will not deposit satisfactorily on natural fibres such as wool.

Both of the above mentioned methods however do not yield the same high quality fabric as is produced by the Axminster and Wilton processes. There are various reasons for this. It is not possible to achieve the same sharp definition of pattern and the penetration of the dye down the pile is poor.

A further attempt to colour the pile of self coloured pile fabrics comprises the use of a plurality of application stations each for applying a single colour to the pile fabric in the form of individual fine jets the operation of each of which is programmed by computer technology in accordance with the pattern to be created on the fabric. As jets of ink are applied to the pile tufts virtually individually it is possible to achieve high quality products using their equipment. However, the equipment is extremely expensive which means that it is out of reach except to only very largest carpet manufacturers.

Space dyeing represents the alternative approach to dyeing the pile fabric after its formation, but the difficulty which is encountered in space dyeng yarns in the keeping of the dyed lengths of the yarns in register with the dyed lengths of all the yarns in the bank of yarns. This it is believed was the problem encountered with the most commonly known, commercially available machine of the spaced dyeing of yarns. In that machine, a bank of yarns to be spaced dyed is passed through a plurality of dyeing stations, each for supplying a single colour to selected lengths of the yarns, by means of absorbent pressure pads between which the yarn is pressed over the length to be dyed.The pads are moved selectively in accordance with the colour pattern to be applied, and one set of pads at each dyeing station is carried by a drum which rotates in the dye bath in order that the pads will pick up the dyestuff.

The aforesaid problem concerning registration arises because a number of dyeing stations are involved, because they must of necessity be physically spaced, and because the yarns travel through these stations unsupported and under the tension necessary to effect the movement of the yarns. Also, there is a differential stretching of different yarns in the bank of yarns being dyed with a consequent loss of register of the dyeing as between the respective yarns, which in the final fabric manifests as a distortion in the pattern, which is of course unacceptable.

The present invention relates to the space dyeing of yarns, but instead of proceeding from an arrangement involving a plurality of printing stations each for the application of a single colour, the present invention arranges for multi-colour dyeing at a single station, so that the disadvantage of differential yarn stretching as between yarns caused by travelling through a plurality of dyeing stages as in the known machine can be avoided.

According to the present invention there is provided an apparatus for the space dyeing of yarns, comprising means for feeding a bank of yarns through the apparatus, a matrix of individual dyeing pads arranged to travel in an endless path, multi-colour dye dispersing heads arranged to apply, in accordance with a pre-selected pattern, individual portions of dyestuff to individual pads of the matrix at an application station in the endless path, means arranged to press the pads,'prnvided with said individual portions of dyestuff, to the yarns at a dyeing station in the said endless path to space dye said yarns in accordance with said pre-selected pattern.

The said individual dyeing pads may be held in individual pockets of an endless belt which is mounted to define said endless path, or alternatively, the pads may be held in pockets on the periphery of a drum. The use of a drum is limited as it would require to be too large to provide for the dyeing ofthe yarns to give a repeat pattern length, in the final fabric, of 36".

It will be appreciated that by effecting the space dyeing (multi-colour) at a single station, the time during which the yarns are unsupported and under tension can be much reduced and according to a preferred feature ofthe invention the yarns are engaged and held by a supporting means immediately after leaving the space dyeing station. Such means may be a supporting conveyor of which the yarn supporting surface is defined by spaced strips of card clothing on the points of which the yarns are supported side by side and in exact register. The supporting conveyor or a number of similar conveyors may be arranged to carry the yarns through a steam chamber to fix the dyestuff and if desired through a washing off bath for removing unfixed dyestuff, and finally through a drying oven and eventually directly to a beaming arrangement.

The pressing of the yarns to the said pads may be achieved bypassing the yarns and endless belt between a pair of pressure rollers to that only a line of pads extending along the pressure line of the rollers is pressed to the yarns at any one time.

One of the rollers preferably has a plurality of projections which correspond to the arrangement of pockets in the endless belts so that the projections enter said pockets to squeeze the yarns to the pads.

The pads of the said belt will be of a nature to retain the individual portions of dyestuff until pressed to the yarns, and to this end they may be pads of non-woven felt, or sponge material which will absorb and release the dyestuff as aforementioned. They should of course be inert to the dyestuff material being used.

An embodiment of the invention will now be described, by way of example, with reference to the accompanying diagrammatic drawing, wherein: Figure lisa side elevation of the apparatus; Figure 2 is a side elevation of a portion of the dyestuff applicator belt; Figure 3 is a sectional elevation showing a row of cells or pockets, the section being taken on line Ill-Ill of Figure 2; Figure 4 is a sectional elevation showing a single cell or pocket, the section being taken on the line IV-IV of Figure 3; Figure 5 is a plan of the row of cells shown in Figure 3, looking in the direction of arrow V in Figure 3; and Figure 6 is a perspective view of a portion of the surface of one of the nip rollers.

Referring to the drawings, the arrangement of the apparatus according to the embodiment is shown in Figure 1, and if reference is made thereto, it will be observed that there is provided a beam 10 on which are wound a bank of yarns to be spaced dyed. The yarns pass from beam 10 around a carborundum roller 12, the rollers 10 and 12 rotating as indicated by the arrows on the drawing, and from the roller 12, the yarns pass around tension rollers 14 and 16, the yarns being indicated by a single line 18, but it is to be appreciated that there will be a plurality of yarns indicated by that line 18, these yarns being arranged parallel. The yarns 18 leave the tension roller 16 in a horizontal plane and pass directly to a printing or dyeing nip defined bytwo pressure rollers 20 and 22. Around roller 20 is trained a dye applicator belt 24.The endless path of travel of the belt-24 is shown in Figure 1 and will be seen that there is line contact at the nip defined by the pressure rollers 20 and 22 and in fact print and press the yarns along that line.

The belt 14 is made up of a plurality of individual pockets or cells, each containing a pad of dyestuff absorbent material which, although it absorbs dyestuff to be applied to the yarn, will release that dyestuff when it is squeezed. If reference is made to Figure 2, a section of the belt 24 is shown where it passes round the roller 20, and the figure shows the end pockets, for example 28 and 30 of parallel rows of pockets which make up the belt and which extend in a direction at right angles to the direction in which the belt moves during operation.

If reference is made to Figures 3,4 and 5, an absorbent pad is contained in each pocket, for example 30 as indicated by numeral 32, and it will be seen that each pocket or cell is of rectangular configuration at the open end thereof and where the absorbent pad 32 is located, the length direction of the rectangular cell or pocket extending in the direction in which the belt 24 moves in operation, and also in the length direction of the yarn at the time of engagement of the yarn by the pad in the appropriate pocket.

During operation, the belt 24 travel continuously in the directions shown by the arrows, being passed around appropriate guide rollers. The belt is driven, and the rows of pads of the belt come into register with corresponding rows of solid projections 26 on the nip roller 22 as shown in Figure 6 and the projections squeeze the yarns to the pads in the pockets so that the individual quantities of dyestuff are squeezed out of the pads and into the yarns in order to effect the space dyeing of a length portion of each yarn corresponding to the length of the pocket or cell.

The dyestuff is injected or otherwise dispensed into the individual pockets from a control mechanism indicated generally by numeral 34 which is programmed to insert dyestuffs of different colours into different cells depending upon the final pattern to be created when the yarns are used in the manufacture of a pile fabric. The dyestuff injection device may be constructed substantially as illustrated in our co-pending British Patent Application No. 7751/76, or any other suitable mechanism may be used for the metering of the individual quantities of dyestuff into the individual pockets or cells of the belt 24.

It will be appreciated from the foregoing that the cells carry the portions of dyestuff until the nip defined by rollers 20 and 22, then each row of cells will come into pressure contact with the yarn and the yarns will be dyed or printed by such pressure. Some of the dyestuff will be expressed onto the surfaces of the complimentary projections of roller 22. The yarns 18 of course move through the nip continuously, and therefore the operation is continuous and a single yarn can be dyed in a number of consecutive length portions, in different colours but is dyed basically at the same dyeing station. The yarns do not have to pass through a plurality of dyeing stations equipped to dye different colours, and therefore as soon as the yarns leave the nip defined by rollers 20 and 22, they can be engaged and supported.In the drawings, a simple conveyor 36 is shown as being provided for the support of the yarns from the point A which is physically as close as possible to the nip between rollers 20 and 22. The conveyor 36 may have spaced parallel strips of card clothing in order lightly to support the individual yarns so that they can readily be removed from the card clothing but in such manner to prevent them from coming out of relative register. The yarns are carried through a steam chamber 38 in which the steam passes between the strips of card clothing to fix the dyestuff on the yarns, and then the yarns eventually are passed through a washing off bath 40 and drying oven 42 before being passed for beaming or indeed before being passed directly to a pile fabric forming,machine, such as a tufting machine or conventional loom.The yarns preferably are removed from the card clothing by a free swinging arm.

Instead of using the simple conveyor 36 as shown it is possible to use twin lattice conveyors having gripper bars which grip the yarns after they have been dyed and after they leave the nip defined by rollers 20 and 22.

Such gripping conveyors would be arranged to grip the yarns at a pitching corresponding to the length of each of the cells or in other words the length of each dyed portion, or each eventual loop of the pile fabric, or a multiple of that pitching, so that the yarns will in fact only be gripped in the region which will form the bottom of the tufts in the eventual fabric.

It will be appreciated that in space dyeing yarns when they are straight as indicated in Figure 1, the pattern produced by the printing of the yarn will be a stretched version of the eventual pattern to be created in the pjle fabric, the stretching being necessary to take account of the fact that the coloured length portions will be folded in two to form individual loops in the fabric. These loops may eventually be cut to form individual tufts.

After the printing is effected by the belt 24, assisted by the roller 22, belt 24 may be cleaned by a washing process prior to returning once more to the nip between rollers 20 and 22 prior to the replenishment of the dyestuff in the individual cells of belt 24. The roller 22 may be washed continuously. It is of advantage to use belt 24 for the space dyeing, because the effective length of such belt can be increased or reduced quite easily, thereby to increase or reduce the pattern pitching of the printing process and in the eventual pile fabric, although it is possible to use a drum with individual cells on the periphery thereof.

The cells or pockets of belt 24 may be formed in removable inserts, whereby the effective dying length may be readily changed by removing one set of inserts and inserting another set of inserts. Likewise the projections of the roller 22 may be individually removable. The roller 22 may be arranged to drop clear of the nip to enable turning over to the machine without feeding yarns therethrough.

Instead of providing a drum 22, there may be two similarly arranged belts, or the roller 22 may be replaced by a simple two reach belt which can be washed at each pass so that any residual dyestuff can be removed therefrom.

The apparatus described has a number of advantages. In particular, printing is effected along a line of pressure defined by the nip between rollers 20 and 22, and along that line of pressure different yarns may be being simultaneously printed in different colours, and control of the movement of the yarns for example by means of a conveyor 36 takes place immediately after printing (within the physical limitations of the equipment) ensuring that the relative register between the yarns can be maintained. This enables the use of the yarns in the subsequent manufacture of pile fabric for the production of high quality patterned pile fabrics.

Although we have described use of steam heating to fix the dyestuffs, it is possible to use radio frequency heating for this purpose. The dyestuff which is used for the printing will essentially be of conventional nature, although some modification of the recipe may be required in order to give most effective space dyeing. For example it may be necessary to modify the type of quantity of wetting our agent in the dyestuff to give effective dyeing of the yarns.

In an alternative arrangement the cells or pockets containing the pads 32 in block 24 receive the pads 32 so that they are recessed in the pockets. A simple, two reach belt in place of roller 22 is used, and that belt is provided with a series of projections which actually engage in the respective pockets of belt 24 along the pressure line. By this means, the yarns will be pressed into the individual pockets and the ends of the lengths of yarn located in the pockets will be nipped or held which will prevent seepage of the dyestuff past the nipped ends of the yarn lengths held in the pockets. The projections of the belt, like the projections or roller 22, may be formed of a solid material such as moulded or machined plastic, and the belt will be associated with a washing bath so that the projections will be washed before being returned once more to the application zone. In practice it is likely to be preferred that when the dye is applied to the yarns, the dyed portions will be separated by small sections of undyed yarn, but the steaming process will be such as to cause sufficient migration of the dyestuff at the ends of the dyed portions so that the dyed portions will in fact merge, perhaps in weaker coloured zones, and eliminate all undyed portions of the yarns.

The dyed yarns will remain in good register one relative to the other until the yarns are beamed, and when the beamed yarns are used for producing a pile fabric, they may be carried by a conveyor which is similar to conveyor 36 so that the card clothing strips will hold the yarns side by side in relative register until very close to the point of weaving.

Claims (10)

1. An apparatus for the space dyeing of yarns comprising means for feeding a bank of yarns through the apparatus, a matrix of individual dyeing pads arranged to travel in an endless path, multi-colour dye dispersing heads arranged to apply, in accordance with a preselected pattern, individual portions of dyestuff to individual pads of the matrix at an application station in the endless path, means arranged to press the pads, provided with said individual portions of dyestuff, to the yarns at a dyeing station in the said endless path to space dye said yarns in accordance with said preselected pattern.

2. An apparatus according to claim 1, wherein the individual dyeing pads are held in individual pockets of an endless belt which is mounted to define said endless path.

3. An apparatus according to claim 1 or claim 2, wherein there is a supporting means arranged to engage and support the yarns after they leave the space dyeing station.

4. An apparatus according to claim 3, wherein said supporting means comprises a conveyor whose conveying surface is defined by spaced strips of card clothing.

5. An apparatus according to claim 4, wherein the conveyor is arranged to carry the yarns through a steam chamber to fix the dyestuff.

6. An apparatus according to any preceding claim, wherein the pressing of the yarns to said pads is achieved by pressing the yarns and pads between a pair of pressure rollers so that only a line of pads extending along the pressure line of the rollers is pressed to the yarns at any one time.

7. An apparatus according to claim 6, wherein one of said rollers serves to guide the endless belt and the other roller has projections which are complimentary to the pads so as to press the pads individually as the belt passes between the said pressure rollers to press the yarns between the pads of the dyestuff application belt and the projections.

8. An apparatus according to claim 7, wherein the roller with projections is constantly cleaned prior to its arrival between the pressure rollers.

9. An apparatus according to any preceding claim, wherein the said pads of the belt are of a nature to retain the individual portions of the dyestuff until pressed to the yarns.

10. An apparatus for the space dyeing of yarns substantially as hereinbefore described with reference to the accompanying drawings.