GB2193980A

GB2193980A - Fabric

Info

Publication number: GB2193980A
Application number: GB08614396A
Authority: GB
Inventors: Kenty Caroline Anne Mc
Original assignee: Individual
Current assignee: Individual
Priority date: 1986-06-13
Filing date: 1986-06-13
Publication date: 1988-02-24
Also published as: GB8614396D0

Abstract

A precursor fabric of open construction, preferably a weft- knitted fabric, is formed from two or more yarns which exhibit different heat shrink characteristics. Heat treatment is effected to produce differential contraction of the yarns. The precursor may be made by knitting or weaving. By using thermoplastic yarns in combination with low shrink yarns such as those of natural fibres it is possible to produce structural fabrics having interesting and useful properties. The shrinkable yarns may form a ground fabric in combination with low shrink pile yarns. Alternatively as shown the shrinkable yarns may form localised bands of one or more courses. Stiff ribs may result which can be formed into three tubes or the like e.g. by sewing or glueing. The heat shrinking step may be performed while the fabric is under restraint or on a mould. Either type of yarn may be inlaid. The shrinkable yarn may be an elastomer. End uses include chair backs, supportive or decorative wear and impact-protective wear. <IMAGE>

Description

SPECIFICATION Fabric This invention relates to fabrics and methods of making fabrics, and particularly but not exclusively to knitted fabrics.

The present invention is concerned essentially with the production of fabrics which make use of differential contraction of different yarns to give fabrics having new and useful structural properties.

Embodiments of the invention will now be described with reference to the accompanying drawings, in which: Figure 1 shows a section of knitted precursor fabric in which several adjacent courses are formed of highly heat shrinkable yarn, while the rest of the section is formed of substantially non-heat shrinkable yarn; Figure 2 shows the precursor fabric of Figure 1 after heat treatment; Figure 3 shows a second knitted precursor fabric analogous to that of Figure 1, but with individual course of substantially non-heat shrinkable yarn in a fabric which is otherwise made up of heat shrinkable yarn; Figure 4 shows the precursor fabric of Figure 3 after heat treatment; Figure 5 shows a second knitted precursor fabric in which individual courses are formed of substantially non-heat shrinkable yarn and a heat shrinkable yarn;; Figure 6 shows the precursor fabric of Figure 5 after heat treatment; Figure 7 shows a knitted precursor fabric of heat shrinkable yarn, into which substantially non-heat shrinkable yarns have been interlaced or woven; Figure 8 shows the precursor fabric of Figure 7 after heat treatment; Figure 9 shows how a precursor fabric can be secured during heat treatment to provide controiled shrinkage; Figure 10 (a) shows a heat treated fabric having alternating stripes of heat shrunk yarn and non-heat shrunk yarn; Figure 10 (b) shows how the heat shrunk yarn stripes can be formed into ridges; Figure 11 shows the application of the fabric of Figure 10 to provide the stiffened back of a chair; Figure 12 shows the application of a heat shrunk fabric to a support garment such as a corset;; Figure 13 shows the application of a heat shrunk fabric to provide a protective and/or decorative feature in an article of clothing; Figure 14 shows how shaped articles can be produced by moulding the precursor fabrics Figure 15 shows how articles produced as in Figure 14 function as part of an article of clothing.

The simplest constructions are those shown in Figures 1 and 3. Here a precursor fabric (pf) is formed of two yarn types. The bulk of the pf is formed of one yarn type, the second yarn type being substituted for the first to produce discrete stripes, bands or panels of the second yarn type. Figure 1 shows such a precursor fabric in which the bulk is of substantially non-heat shrunk yarn such as cotton or rayon, in which several adjacent courses of a high heat shrunk yarn such as a thermoplastic monofilament or heat shrinkable polypropylene are included. Figure 3 shows the reverse configuration.

On heating these fabrics (using either dry or steam heat) to a point where the heat shrinkable yarn or yarns contract, the fabrics undergo dramatic changes in appearance and feel. With the pf shown in Figure 1, the result, Figure 2, is to produce a stiff rib in an otherwise flexible fabric. With the pf shown in Figure 3, the result, Figure 4, is to produce a series of stiff ribs or panels linked or articulated by means of flexible, linear joints.

The pf shown in Figure 5 is made by knitting with what is effectively a composite yarn, made up of a heat shrinkable yarn and a substantially non-heat shrinkable yarn. Again, in a single piece of fabric, panels or rows can be formed of other yarn types or other combinations of yarns. When the pf of Figure 5 is heat treated, the heat shrinkable yarn shrinks away from the non-heat shrinkable yarn, creating a loop pile fabric, Figure 6. The depth of the pile depends upon the knitted tension of the pf, lower tension giving a deeper pile.

The heat shrinkable yarn may conveniently be a thermoplastic monofilament, and the substantially non-heat shrinkable yarn may be a polyester. By using different colours/shades for the two yarn types it is possible to create attractive effects.

The fabric shown in Figure 6 can be further processed by cutting, breaking or otherwise opening the loops to produce a "hairy" fabric.

Where the heat shrink yarn has not contracted sufficiently to retain the cut yarn, a backing, adhesive or other retaining means could be used, but in general sufficient shrinkage can be achieved. The combination of a soft pile, whether loops or ends, with a dense taught backing gives the fabric an unusual feel and an attractive appearance.

Another unusual but useful effect can be achieved by knitting a precursor fabric of heat shrinkable yarn and inlaying or weaving-in a substantially non-heat shrinkable yarn, as shown in Figure 7. The inlaying is preferably achieved by means of an inlay needle while the main fabric matrix is being produced. Conveniently a double bed knitting machine is used to produce the main matrix, and an inlaying carriage used for inlaying. A particularly interesting fabric is produced by using a heat shrinkable elastomeric yarn for the main matrix, and a flat polypropylene tape for the inlay. Although the polypropylene is heat shrin kable, the elastromeric yarn shrinks at a much lower temperature than the polypropylene, so it is possible to shrink the matrix without appreciably shrinking the polypropylene.However, by using higher temperatures it is of course possible to shrink both yarns, should this be desired.

The elastomeric matrix and polypropylene inlay gives a fabric having a useful elasticated support effect. By using relatively broad polypropylene strip (say 2-3mm wide by perhaps 1-2mm thick) a particularly useful combination of support, elasticity and flexibility is achieved.

A typical application of such a fabric is to support/foundation garments as shown in Figure 12. The polypropylene is here arranged to extend up the body, allowing the flexible matrix to conform around the torso. By increasing the size and/or number of inlays, fabric having particular application to protective clothing can be produced.

The fabrics according to the invention offer another way of providing substantial ribs or other protruberances integral with fabric matrix whose properties can be tailored to choice. In Figure 10, a fabric including several stripes of heat shrunk material is further processed by having the generally 2-dimensional stripes formed into tubes or rods. The stripes can be sewn, glued or further heat formed to form clearly 3-dimensional parts. The thus processed fabric can be used as shown in Figure 3 to provide decorative or protective components for garments.

Fabric including heat shrunk stripes, whether or not further processed as just described, can be used to form directionally supportive panels/parts of furniture such as chairs, as shown in Figure 13.

When heat shrinking the precursor fabrics, the amount of shrink is to some extent determined by the degree to which the precursor is constrained. If the precursor is held in a stretched state, there may be little or no shrinkage, and over-heating could result in yarn breakage. If the precursor is totally unconstrained, however, there is the possibility of uneven shrinkage leading to unwanted distortion. Where such unwanted distortion is encountered, its incidence can be reduced by carrying out the shrinkage with the precursor constrained but with sufficient slack to allow the desired degree of shrinkage, as shown in Figure 9.

By using a mould or pattern during heat treatment, Figure 14, it is possible to produce moulded in shapes.

Depending upon the yarn, its thickness and the extent of heat treatment, such moulded in features can be made substantially rigid (for a cricket box, for example), or as somewhat yielding shapes such as for the breast cups of Figure 15.

The precursor fabrics according to the present invention are most easily implemented by knitting, although it is possible to produce variants by weaving.

With prolonged or intense heat treatment it is possible to produce virtually a solid, rigid mass of plastic, integral with the rest of the fabric.

Claims

1. A method of making a fabric, comprising the steps of: (a) forming a precursor fabric of open construction from a combination of a heat shrinliable yarn and a non heat shrinkable yarn; (b) heat treating said precursor fabric to produce heat shrinkage of said heat shrinkable yarn.

2. A method as claimed in claim 1 wherein said precursor fabric is formed by knitting together the heat shrinkable yarn and the substantially non-heat shrinkable yarn.

3. A method as claimed in claim 2 wherein at least some of the coursea of said precursor fabric are formed of both the heat shrinkable and the non-heat shrinkable yarn.

4. A method as claimed in claim 3 in which the fabric formed as the result of the heat treatment step comprises full loops of the non-heat shrinkable yarn oustanding from a matrix of the heat shrunk yarn.

5. A method as claimed in claim 3 in which at least part of the fabric formed as the result of the heat treatment step comprises loops of the non-heat shrinkable yarn securely retained by the heat shrunk yarn.

6. A method as claimed in claim 5 further comprising the step of opening the secured loops of the non-heat shrunk yarn to produce a hairy fabric.

7. A method as claimed in claim 2 wherein a heat shrinkable yarn is inlaid during the knitting of the precursor fabric.

8. A method as claimed in claim 7 wherein apart from the inlay, all the yarn making up the precursor fabric is a substantially non-heat shrinkable yarn.

9. A method as claimed in claim 2 wherein a substantially non-heat shrinkable yarn is inlaid during the knitting of the precursor fabric.

10. A method as claimed in claim 9 or any one of claims 1 to 7 wherein the heat shrinkable yarn is present in the precursor fabric in the form of localised bands.

11. A method as claimed in claim 10 wherein the precursor fabric is a knitted fabric and said bands consist of one or more courses of heat shrunk yarn.

12. A method as claimed in claim 10 or 11 wherein the heat treatment causes the yarn in the localised bands to form stiff ribs, the substantially non-heat shrinkable yarn extending between and connecting adjacent ribs.

13. A method according to any one of the preceding claims wherein the heat treatment of the precursor fabric is carried out with that fabric allowed to freely contract during yarn shrinkage.

14. A method as claimed in any one of claims 1 to 12, wherein at least part of the precursor fabric is constrained to conform to a mould or pattern during heat treatment.

15. A fabric made according to the method of any one of claims 1 to 14.

16 A fabric substantially as hereinbefore described with reference to any one of the accompanying drawings.