GB1565047A

GB1565047A - Colouring of pile fabrics

Info

Publication number: GB1565047A
Application number: GB3906275A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1976-07-22
Filing date: 1976-07-22
Publication date: 1980-04-16

Description

(54) IMPROVEMENTS RELATING TO THE COLOURING OF PILE FABRICS (71) I, RICHARD DONOVAN GLOVER, a British Subject of c/o Gedham Mills, Ossett WF5 9DA, Yorkshire, do hereby declare the invention for which I pray that a patent may be granted to me, and the method by which it is to be performed, to be described in and by the following statement: This invention relates to a method for the colouration of pile fabrics such as tufted fabrics, flock fabrics, woven fabrics and nonwoven fabrics and which include a base, backing and/or reinforcement sheet structure, and also relates to a pile fabric coloured in accordance with the method and a pile fabric for use in the said method.In producing tufted carpets the yarns are tufted through a backing sheet, which may be of fibrous material such as hessian or jute, and similarly in the manufacture of needled non-woven fabrics it is usual to needle the fibrous laps which form the pile of the finished fabric through a reinforcing sheet structure, which may be a cotton scrim.

The present invention has particular application for the production of a coloured pattern, which may be multi-coloured in the pile of such fabrics, although the invention can be used for overall colouration of the fabrics.

Several methods for the colouration of pile fabrics are known. In a commonly practiced method, the pile fabric is screen printed, washed and then dried.

In another method, the fabric is transfer printed using sublimable dyes wherein the dyes are carried on a transfer printing sheet which is applied to the fabric pile and the sandwich is subjected to heat to release the dyestuff so that it transfers to and remains with the pile of the fabric.

The drawback with the first method is that it is expensive and slow and in the subsequent washing and drying, the fabric may shrink.

The drawback of the second method is that the penetration of the dyestuff with the pile is not complete and usually only the top of the pile is dyed. In many cases the depth of dyestuff penetration into the pile is of commercial quality but in other cases it fails to meet requirements. Thus, in the trade it is generally agreed that the dyestuff penetration into the pile using a transfer printing method has not been completely solved.

In an alternative proposal, it has been suggested that in the case of tufted fabrics, the yarns should be space-dyed which involves applying colour over selected lengths of individual yarns before they are tufted into the backing sheet, so that these coloured lengths eventually define coloured tufts in the tufted carpet, and by virtue of the selection of particular lengths of colour for the particular yarns, so the desired colour pattern is created in the tufted carpet. The yarns can be dyed either by a wet process or by transfer printing. This method suffers from a number of drawbacks. When a wet process is used, it is difficult to dye certain lengths of individual yarns exactly and there is always the danger of the liquid dyestuff running or dripping.

Generally speaking, attempts to space-dye yarns using wet processes have been abortive.

With the transfer printing of yarns and the wet process, to space-dye the yarns there is always the problem of registration in that after the yarns have been space-dyed it is difficult on the one hand to keep all the space-dyed yarns in the correct positions one relative to another which is essential to the location of the pattern in the fabric, and it is also difficult to keep the individual yarns in correct register with the tufting machine.

The present invention provides a new approach to colouring pile fabric and provides a method for the colouration of pile fabrics having a backing or reinforcing sheet structure, wherein the backing or reinforcing sheet structure is printed with sublimable dyestuff in accordance with the colouration required in the fabric pile before the material which defines the pile is connected to the backing or reinforcing sheet structure, the material which defines the pile is connected to the backing or reinforcing sheet structure, and tile fabric is subjected to heat treatment to cause the dyestuff to sublime and migrate from the said backing or reinforcing sheet up the pile of the fabric.

The heat trettinent preferably is carried out in a sub-atmospheric pressure environ ment, a',. such an environment, by and large, hllploves the rate at which sublimable dyes tulles sublime. Furthermore, by creating a pressure differential across the fabric during the heating, migratory movement of the dyestuff can be assisted even further. As the invention rclies on migration of the dyestuff through the pile then it is cnsured that the dyestuff will be present in the pile to a sufficient depth.

l hc backing sheet may, for example, be a wovcn hessian sheet or other conventionally used backing sheets for pile fabrics. The backing sheet in the invention therefore serves two purp)ses, namely its conventional purpose and also as a temr)or.lry carricr for the dyestuff.

After the colouration process it may be desirable to wash the fabric to remove residue remaining in the backing sheet.

Also according to the invention there is provided a pile fabric for use in the method as aforcsaid comprising material defining the pile connected to a backing or reinforcing sheet structure, which sheet structure has been printed with sublimable dyestuff in accordance with the colouration required in the pile fabric before the material which defines the pile is connected to said sheet structure.

An embodiment of the invention will now be described, by way of example, with reference to the accompanying diagrammatic drawing, wherein: Figure 1 shows a section of a backing sheet printed with a simple pattern to be re-created in a pile fabric of which the sheet is to form a part; Figure 2 illustrates the tufting operation which creates the pile on the sheet of Figure 1; and Figure 3 shows a part of the fabric in enlarged section during a preferred method or releasing the dyestuff from the backing sheet.

Referring to the drawings, in Figure 1 there is shown a backing sheet for a tufted carpet, this sheet being of, for example, woven hessian yarns of the type which has been used heretofore in the production of tufted carpets. The sheet is shown as being of finite size in the interests of simplicity of description, but it is to be appreciated that it may be a continuous web. One surface, the upper surface in Figure 1, of the sheet 10 is shown as being printed so as to have a diagonal striped pattern 12. The Dyestuffs used for this printing are sublimable dyestuffs of the type commonly used in conventional transfer printing where the print is placed on a carrier sheet of paper or other material.It is to be mentioned here that the colour could completely covcr the sheet 10, or could be in a differcnt pattern and the pattern may even be multi-coloured. The printing may be effected by conventional processes such as silk screen printing. Upon completion of the printing of the sheet 10, this is supplied to a tufting machine illustrated diagrammatically in Figure 2. A tufting head 14 having tufting needles 16 is supplied with a warp of yarns lX and these yarns are tufted through the sheet 10 as indicated clearly in Figure 2. Figure 2 also shows a loop cutter knife 20 for cutting the loops of yarn formed in the tufting operation to provide a cut pile tufted fabric. The sheet 10 is arranged so that the printed pattern 12 is on the underside in Figure 2.That is to say, in the finished fabric, the printed pattern will reside at the roots of the tufts of yarn.

Next, the fabric thus produced is subjected to a heat treatment in order to cause the dyestuffs to sublime. That is to say, the dyestuff becomes airborne and migrates up the pile to the ends thereof. Figure 3 illustrates diagrammatically one preferred method of effecting the migration of the dyestuff. The fabric is heated between a pair of platens 22 and 24 which are of sintered metal. In addition to applying the heat to the fabric at this stage, there is also created an air flow indicated by arrows 26 and 28 between the platens 22 and 24 and also the fabric therebetwren. This air flow induces the airborne dyestuff to travel what is in fact up the pile, although the direction of flow is downwards in Figure 3. This ensures that the dyestuff reaches the tuft tips effectively ensuring homogenous dyeing throughout the pile height. The pattern originally applied to the sheet 10 will be therefore re-created in the pile of the fabric and be visible at the pile surface.

It should be mentioned that the fabric when at the stage of Figure 3, will be very porous, and the air flow through the fabric will be freely established. It is preferable that the sublimation process, i.e. heating the fabric to release the dyestuff, be carried out in a sub-atmospheric environment. In this connection, the air flow referred to above may be established by the application of a vacuum to the underside of plate 24.

The apparatus illustrated diagrammatically in Figure 3 is in fact a flat head press arrangement. It is to be appreciated that the method can be carried out on a rotary principle where the fabric travels round a drum the centre of which is vacated and the periphery of which is perforated. In another arrangement the fabric can be passed between the nip of heated rollers, as some dyestuffs will migrate freely of their own accord to the ends of the tufts of fabric.

The material of the pile can be any which is suitably receptive to the sublimable dyes, and following completion of the dyeing process as indicated in Figure 3, the fabric may be provided with a rubberised or heavy plastics material backing to complete the fabric.

The degree of vacuum which is desirable, where vacuum is used, during the sublimation process will depend upon the dyestuffs being used, but generally speaking it is known to use vacuum to release these dyes, and also known are the temperature ranges which must be used for the heating of the dyestuffs in order to achieve effective dyestuff release.

In addition to or instead of the creation of an air flow through the fabric as the dye stuffs are subliming, an electrostatic field may be supplied across the fabric in order electrically to induce the vapourised dyestuff particles to move up the pile. The dyestuff may be rendered electrically charged by having appropriate particles therein in order to assist the dyestuff movement under the influence of the electrostatic field. It may be possible to achieve the same effect with a magnetic field.

In modification, the heating of the fabric is by micro-wave energy. Where the pile has sufficient moisture content it will not be necessary to dampen the pile further, but this can be done if necessary. The use of microwave heating has the advantage that the whole of the pile is heated evenly, and this assists in the migration of the dyestuff throughout the pile height. The use of micro-wave heating can be in conjunction with the establishment of an air flow throughout the pile height and/or the use of a magnetic or electric field as mentioned above.

As stated herein, the method can be used for textile fabric pieces of finite lengths such as tiles or rugs, or it can be used for continuous webs such as broadloom webs. In either case the method can be carried out using machinery as described in my British Patents No.s 1,367,108 or No. 1,490,873.

WHAT WE CLAIM IS: 1. A method for the colouration of pile fabrics having a backing or reinforcing sheet structure, wherein the backing or reinforcing sheet structure is printed with sublimable dyestuff in accordance with the colouration required in the fabric pile before the material which defines the pile is connected to the backing or reinforcing sheet structure, the material which defines the pile is connected to the backing or reinforcing sheet structure, and the fabric is subjected to heat treatment to cause the dyestuff to sublime and migrate from the said backing or reinforcing sheet up the pile of the fabric.

2. A method according to claim 1, wherein the heat treatment is carried out in a sub-atmospheric environment.

3. A method according to claims 1 or 2, wherein a flow of air is created through the fabric during said heating to cause the dyestuff to migrate from the sheet structure up the pile of the fabric.

4. A method according to any preceding claim wherein the backing or reinforcing sheet structure is woven hessian sheet structure.

5. A method according to claim 1, for the colouration of pile fabrics substantially as hereinbefore described.

6. A pile fabric produced in accordance with the method of any of the preceding

Claims

claims.

7. A pile fabric for use in the method of claim 1, comprising a material defining the pile connected to a backing ox reinforcing sheet structure, which sheet structure has been printed with sublimable dyestuff in accordance with the colouration required in the pile fabric before the material which defines the pile is connected to said sheet structure.