GB1588400A

GB1588400A - Stitch bonded fabric

Info

Publication number: GB1588400A
Application number: GB2490078A
Authority: GB
Original assignee: Cosmopolitan Textile Co Ltd
Current assignee: Cosmopolitan Textile Co Ltd
Priority date: 1978-05-31
Filing date: 1978-05-31
Publication date: 1981-04-23

Description

(54) STITCH BONDED FABRIC (71) We, COSMOPOLITAN TEXTILE COMPANY LIMITED, of Road Five, Industrial Estate, Winsford, Cheshire, a British company, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to stitch bonded fabrics.

Such fabrics are composed of a web of fibre, usually a cross-folded, carded web, stitched together by rows of warp yarn chain stitches. The chain stitches may be in either unconnected rows (i.e. in pillar stitch formation) or in connected rows (i.e. in tricot, or other more complicated stitch formations). Fabrics which have pillar stitches display satisfactory warp strength and stability, though fabrics which have only pillar stitches tend to lack weft strength and are inadequate for use where the fabric will be subject to stress. Weft strength in fabrics having only pillar stitches can be improved by shortening the stitch length. But this reduces the rate of production and correspondingly increases the cost of the fabric.

Fabrics, on the other hand, having tricot stitches instead of pillar stitches tend to lack stability in both warp and weft directions, as the stitch structure behaves elastically.

Some fabrics, made on two guide bar machines, have two sets of warp thread stitches. One set can be of pillar stitches, and the other set of tricot stitches. Such fabrics now possess both warp strength and improved weft strength even at acceptably long stitch lengths. However, there is still an increased cost of such fabrics over the cost of single bar fabrics, due to increased yarn content and reduced manufacturing speed of the two bar machines, and this has led to single bar fabrics being preferred for most purposes even though weft strength is not as good as desired. Consequently, two bar fabrics have received relatively little attention from the point of view of the development of improved properties.

Two bar fabrics have been exploited to some extent, however, for the greater versatility of patterning available. Single bar fabrics are limited in this regard. Practically the only permissible modification in a single bar fabric is the omission of occasional warp threads to leave a raised stripe effect in the fabric. Two bar fabrics have been proposed, in Patent Specification No.

1 479 714, in which in addition to a pillar stitch structure, there is a tricot stitch structure, which may be made with incomplete threading. In addition to any warp striping produced by omission of warp threads, a weft striping, to achieve a check effect, is produced by occasionally traversing the tricot stitch threads over two needle spaces instead of one. Aside from this, two bar fabrics, with one bar knitting pillar stitch and the other bar knitting tricot, have had a flat, substantially textureless and uninteresting surface. They have been used in dressing growns and such after raising.

It has now been found, however, that fabrics can be made using two bar constructions that have substantially improved properties, as well as improved appearance.

The present invention comprises a stitch bonded fabric made on a two guide bar machine, having a first, full set of pillar stitches made on one bar and a second set of threads traversed by the other bar over two or three needles, in which the stitch length is between 1.2 and 2 mm, the fabric weight is between 150 and 300 grams per square metre and the weft strength is greater than the warp strength which is greater than 40 kilograms per 50 mm strip.

The said second set of threads may also be a full set. In a preferred arrangement, a full set second set of threads is laid in over two needles.

However, the second set of threads need only be a part set -- preferably a half set.

In preferred arrangements, a part set second set of threads is traversed over three needles and may be laid in or stitched in tricot formation.

By "full set" in regard to said first set of stitches is implied also a substantially full set, that is to say, the omission of occasional threads for a longitudinal stripe effect, in the same way as is now conventional for single bar fabrics, is not ruled out. Variations can likewise be made in the threading of the second bar -- though where this is a part set threading, such variations preferably involve the insertion of extra threads rather than the omission of threads.

In addition, some variation is also permitted in the disposition of the second set of threads. Where predominantly, for example, they extend over three needles of the first set, occasionally they may extend over only two needles in isolated courses or small groups of courses. This will achieve a similar lateral stripe or check effect as described in Specification 1 479 714 above mentioned. Nor is extending over four or more needles on all or some courses ruled out.

It is found that the complete or substantially complete lateral connection effected by even half set threading on the second bar gives a very surprising increase in the weft strength of the fabric. Furthermore.

and more surprising still, the resistance to pilling - a principal failing of most non woven fabrics this is very much improved.

Improved weft strength and pilling resistance have previously only been obtained with the aid of an adhesive bonding of the web fibres. This, however, is an additional step in the manufacture of a stitch bonded fabric, which of course increases the manufacturing cost thereof. The adhesive bonding, moreover, if it is to be effective at all, leads to an increased stiffness of the fabric giving rise to poor handling properties.

Furthermore, the combination of a full set pillar stitch and a half set tricot stitch or laid in formation as described leads to a much more attractive surface texture.

These factors not only make possible improved stitch bonded fabrics for the current range of end uses, but also enable stitch bonded fabrics to serve additional end uses.

One important end use is in upholstery fabrics. Stitch bondeds have been said to be suitable for use in upholstery, though in practice, their appearance and performance have usually fallen well short of conventional woven and knitted fabrics.

Upholstery fabrics can be made, however, using the present invention, which are equal to woven fabrics in performance, which have an attractive surface texture, and which are less expensive to produce.

One embodiment of a fabric and the method for making the same will now be described with reference to the accompanying drawings, in which: Figure 1 is a point pattern for the stitches on one bar of a two bar stitch bonding machine, Figure 2 is a point pattern for the stitches on the other bar of the same machine, and Figure 3 is a diagram of the underlaps of the stitches on the face side of the fabric produced when the machine is operated according to Figures 1 and 2, and Figures 4 to 7 are point patterns for the said other bar to produce fabrics of different appearance.

The threading shown in Figure 1 is a full set threading on the top or front bar of a two bar stitch bonding machine such as an Arachne or Maliwatt machine, the bar being arranged to knit pillar stitches. The threading shown in Figure 2 is a half set threading on the bottom or back bar, which is arranged to knit tricot stitch, extending, however, over three needles instead of the usual two.

Figure 3 shows how the underlaps of the two stitching systems appear on the face of the fabric. The diagonally extending underlaps 31 of the tricot stitches lie underneath the warp-wise extending underlaps 32 of the pillar stitches, where they cross. This avoids having long free floats which might snag.

A 100% polyester fabric made from 100 mm polyester staple fibre and 167 dtex polyester stitching yarn on both bars can be made as a 290 gm/sq. metre upholstery fabric. A preferred gauge is 18, and a preferred stitch length is the range 1.2 mm to 1.6 mm. Such fabrics have weft strengths in the region of 90 kg per 50 mm strip, which is about twice the weft strength of single bar fabric of comparable weight and guage.

The fabrics have warp strengths of about 70 kg per 50 mm strip. The pilling resistance is also very substantially better than single bar fabric, and these properties enable it to be used in hard wearing upholstery applications.

The fabric has comparable strength to a fabric made with full set threading on the bottom or back bar making tricot stitches over one needle space. It is, however, less expensive to produce because of the reduced yarn content, and has a much more interesting surface texture.

Figure 4 shows a half-set threading on the back bar, which is laid in over three needles. Occasionally, as at 41, however, the pattern is set to lay in over only two needles. This will give a weftwise stripe effect.

Figure 5 shows a full set threading on the back bar, with, however, the occasional missed thread as at 51. The pattern is set to lay in these threads over two needles, though occasioinally, to give rise to a weftwise stripe in addition to the warpwise stripe occasioned by the missed threads, the patern lays in on one needle only, as at 52 and 53.

Figure 6 shows another half set threading on the back bar, but with occasional extra threads as at 61 to produce a warpwise stripe effect. In this design, the back bar knits tricot stitch over three needles.

However to produce a warpwise stripe effect, occasionally, as at 62 the stitch is taken over only two needles.

Figure 7 shows a back bar full set threading laid in over two needles. To produce a check effect, an occasional thread is missed as at 71, and the pattern is taken over four needles occasionally as at 72.

In these and other ways either warpwise stripes or widthwise stripes or both can be produced with any desired spacing, and a variety of interesting textures and patterns produced.

Fabrics having improved warpway strength and substantially improved weftway strength, as compared with single bar fabrics, can be produced with the addition of relatively little stitching thread. If, for example, full set threading is used, this can simply be laid in, rather than stitched in, and this uses relatively less thread.

Stitch bonded fabrics produced according to the invention have been made on 14 and 18 gauge, two guide bar machines threaded with a full set of threads on the front bar, set to knit pillar stitch, and the back bar set to traverse a second set of threads, either a part or a full set, over two or three needles.

Stitch lengths lie between 1.2 and 2.0 mm, and fabric weights between about 150 and 300 grams per square metre. The fabrics were tested for warp and weft strength using 25 x 5 cm strips, with 20 cm between the jaws of the testing instrument, the instrument being operated at a constant rate of extension of 10 cm/minute. The following Examples are typical.

EXAMPLE I A 175 gram/sq. metre fabric was made of 100% polyester fleece stitched with 167 dtex polyester continuous filament stitching thread. The back bar was half-set threaded and patterned to knit three needle tricot.

The stitch length was 1.59 mm. The warpway breaking load was 51.4 kgs (an average of 10 tests, as are all subsequent results). The weftway strength was, surprisingly, higher than the warpway strength at 59.1 kgs. For comparison, an identical fabric was made, but without the back bar threading. Its weftway breaking load was nearly 20% lower than its warpway breaking load.

EXAMPLE II A fabric was prepared exactly like EX- AMPLE I, but with a heavier fleece, tc weigh about 260 gms/sq. metre. The warpway breaking load was 72.9 kg. The weftway breaking load was a surprising 97.9 kg.

Similar fabrics produced using the variations in back bar threading and patterning described with reference to Figures 4 to 7 shared only insubstantially different breaking load test results.

WHAT WE CLAIM IS: 1. A stitch bonded fabric made on a two guide bar machine, having a full set of pillar stitches on one bar and a second set of threads traversed by the other bar over two or three needles, in which the stitch length is between 1.2 and 2 mm, the fabric weight is between 150 and 300 grams per square metre, the warp strength is greater than 40 kilograms per 50 mm strip, and the weft strength is greater than the warp strength.

2. A stitch bonded fabric according to claim 1, in which the said second set of threads is a full set.

3. A stitch bonded fabric according to claim 2, in which the said second set of threads is laid in over two needles.

4. A stitch bonded fabric according to claim 1, in which the said second set of threads is a part set.

5. A stitch bonded fabric according to claim 4, in which the said second set of threads is a half set.

6. A stitch bonded fabric according to claim 4 or claim 5, in which the said second set of threads is laid in over three needles.

7. A stitch bonded fabric according to claim 4 or claim 5, in which the said second set of threads is stitched in tricot formation over three needles.

8. A stitch bonded fabric according to any one of claims 1 to 7, in 14 gauge or finer.

9. A stitch bonded fabric according to claim 8, in 18 gauge.

10. A stitch- bonded fabric according to any one of claims 1 to 9, having a stitch length of about 1.6 mm.

11. A stitch bonded fabric substantially as hereinbefore described with reference to the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. extra threads as at 61 to produce a warpwise stripe effect. In this design, the back bar knits tricot stitch over three needles. However to produce a warpwise stripe effect, occasionally, as at 62 the stitch is taken over only two needles. Figure 7 shows a back bar full set threading laid in over two needles. To produce a check effect, an occasional thread is missed as at 71, and the pattern is taken over four needles occasionally as at 72. In these and other ways either warpwise stripes or widthwise stripes or both can be produced with any desired spacing, and a variety of interesting textures and patterns produced. Fabrics having improved warpway strength and substantially improved weftway strength, as compared with single bar fabrics, can be produced with the addition of relatively little stitching thread. If, for example, full set threading is used, this can simply be laid in, rather than stitched in, and this uses relatively less thread. Stitch bonded fabrics produced according to the invention have been made on 14 and 18 gauge, two guide bar machines threaded with a full set of threads on the front bar, set to knit pillar stitch, and the back bar set to traverse a second set of threads, either a part or a full set, over two or three needles. Stitch lengths lie between 1.2 and 2.0 mm, and fabric weights between about 150 and 300 grams per square metre. The fabrics were tested for warp and weft strength using 25 x 5 cm strips, with 20 cm between the jaws of the testing instrument, the instrument being operated at a constant rate of extension of 10 cm/minute. The following Examples are typical. EXAMPLE I A 175 gram/sq. metre fabric was made of 100% polyester fleece stitched with 167 dtex polyester continuous filament stitching thread. The back bar was half-set threaded and patterned to knit three needle tricot. The stitch length was 1.59 mm. The warpway breaking load was 51.4 kgs (an average of 10 tests, as are all subsequent results). The weftway strength was, surprisingly, higher than the warpway strength at 59.1 kgs. For comparison, an identical fabric was made, but without the back bar threading. Its weftway breaking load was nearly 20% lower than its warpway breaking load. EXAMPLE II A fabric was prepared exactly like EX- AMPLE I, but with a heavier fleece, tc weigh about 260 gms/sq. metre. The warpway breaking load was 72.9 kg. The weftway breaking load was a surprising 97.9 kg. Similar fabrics produced using the variations in back bar threading and patterning described with reference to Figures 4 to 7 shared only insubstantially different breaking load test results. WHAT WE CLAIM IS:

1. A stitch bonded fabric made on a two guide bar machine, having a full set of pillar stitches on one bar and a second set of threads traversed by the other bar over two or three needles, in which the stitch length is between 1.2 and 2 mm, the fabric weight is between 150 and 300 grams per square metre, the warp strength is greater than 40 kilograms per 50 mm strip, and the weft strength is greater than the warp strength.

9. A stitch bonded fabric according to claim 8, in 18 gauge.