EP0542947B1

EP0542947B1 - Warp knitted tape

Info

Publication number: EP0542947B1
Application number: EP92909759A
Authority: EP
Inventors: Kenneth Alfred Allen
Original assignee: Brightwake Ltd
Current assignee: Brightwake Ltd
Priority date: 1991-05-29
Filing date: 1992-05-18
Publication date: 1996-04-10
Anticipated expiration: 2012-05-18
Also published as: ES2088139T3; WO1992021805A1; DE69209779D1; DE69209779T2; GB9111542D0; EP0542947A1

Abstract

A method of producing a warp knitted tape having a loop pile, the method including the steps of knitting a ground fabric by knitting a plurality of straight wales (12) from wale forming yarn and during knitting of the wales laying-in across said plurality of wales on selected courses at least one weft yarn (14), and during knitting of the ground fabric, knitting-in along selected wales a textured yarn (16), the textured yarn being floated across adjacent wales (12) or courses at selected locations to define a float (17) on the surface of the ground fabric at said selected locations, the textured yarn being knitted-in under tension and permitted to relax in the region of the floats (17) after knitting in order to produce a loop pile comprising a mat of tangled loops.

Description

The present invention relates to a warp knitted tape having a loop pile for use in a touch and close fastener such as Velcro (RTM).
For a touch and close fastener it is desirable to provide a loop pile tape with a high density of loops for the hook pile of the mating tape to engage with whilst keeping usage of the loop forming yarn to a minimum. It is also desirable to provide a ground fabric construction which is resistive to distortion or deformation caused by pulling away of the hook pile of the mating tape.
EP-A-0284020 discloses a warp-knit tape for use in hook-and-loop fasteners comprising a pile portion and selvage portions on opposite sides of the pile portion. The pile portion includes pile-loops arranged to extend longitudinally in a meandering fashion so as to prevent the same from tilting down flat on the surface of the tape.
FR-A-1539 997 discloses a method and apparatus for the manufacture of a knitted fabric with a fluffy appearance.
According to one aspect of the present invention there is provided a method of producing a warp knitted tape having a loop pile, the method including the steps of knitting a ground fabric by knitting a plurality of straight wales from forming yarn and during knitting of the wales laying-in across said plurality of wales on selected courses at least one weft yarn, and during knitting of the ground fabric, knitting-in along selected wales a textured yarn, the textured yarn being floated across adjacent wales or courses at selected locations to define a float on the surface of the ground fabric at said selected locations, the textured yarn being knitted-in under tension and permitted to relax in the region of the floats after knitting in order to produce a loop pile comprising a mat of tangled loops.
According to another aspect of the present invention, there is provided a warp knitted tape having a loop pile, the tape comprising a warp knitted ground fabric having a textured yarn knitted-in to produce floats of textured yarn on the surface of the ground fabric, the floats of textured yarn defining a loop pile comprising a mat of tangled loops. Preferably the mat has a depth less than 3 mm and more preferably is about 1 mm in depth.
Reference is now made to the accompanying drawings, in which :-

Figure 1 is a schematic diagram of a portion of tape according to a first embodiment of the invention,
Figure 2 is a similar view to Figure 1 of a second embodiment of the present invention,
Figure 3 is a schematic illustration of a band of the present invention which is adapted for forming a releasable continuous band.

Referring initially to Figure 1, there is shown a tape 10 including a ground fabric knitted from a plurality of straight wales 12 and a series of weft loops 14.
A textured yarn 16 is knitted-in along selected wales 12 and at selected locations is floated across to an adjacent wale to create a float 17.
Preferably inbetween the locations of floating the yarn 16 to an adjacent wale, the textured yarn is knitted-in on at least two consecutive courses. This ensures that the textured yarn 16 is anchored within the ground fabric and is resistive to pull-out or causing deformation of the ground fabric when a male tape of a touch and close fastener is pulled away.
The textured yarn 16 is knitted-in under tension so as to enable a stitch to be formed. The float 17 is therefore also laid-in under tension and in order to ensure that the float is proud of the surface of the ground fabric it is preferably floated across a loop forming finger so as to have a length greater than the distance between the adjacent stitches at each end of the float. Preferably the loop forming finger creates a loop of about 3-5 mm in height before relaxation. Thus, after knitting the floats 17 are allowed to relax and bulk up in accordance with the texture which has been applied thereto.
The textured yarn is preferably a knit-deknit yarn so that when the floats relax a multiplicity of complex loops are created which collectively form a mat of tangled loops. For a curtain header tape, the yarns for producing the wales and weft loops of the ground fabric are preferably synthetic monofilament yarns such as a polyester having a diameter of about 0.14 mm for both the warp and weft.
The hook pile of the male touch and close tape is usually formed from a mono-filament yarn, such as a nylon or polyester having a diameter of .18 mm - .20 mm and so is of similar characteristics to the weft loop yarn. Accordingly, if the ground fabric is engaged by the hook pile of the male tape it is not distorted by removal of the male tape. Thus, it is possible to have a ground fabric of mono-filament yarn which is of an open structure into which the hook pile may accidentally penetrate. Typically, the distance 'd' between each leg of the weft loops is about 1 mm. The distance d may be varied as desired by laying-in the weft on every n^th course where n ≥ 1. The knit-deknit yarn is preferably a polyamide multifilament yarn. The knit-deknit yarn, prior to knit-deknit preferably has a decitex value of about 220 dtex and has about 10 filaments. The polyamide is preferably a Nylon 66 (RTM). To provide an adequate density of loop pile for engagement with the male tape, the wales 12 are spaced apart by a relatively wide distance in order to provide each float with a relatively wide span. Typically, the distance between adjacent wales 12 is in the range of 3-5 mm.
For use as a curtain header tape, the loop pile is preferably created in discrete mat areas spaced along (and possibly across) the tape. These areas may be typically 25 mm long by 10 mm wide. The width dimension of the mat area is typically created by 3 ends of the knit-deknit yarn being knitted-in along each of 3 wales. In between the discrete mat areas the textured yarns are preferably each laid-in on consecutive courses along single wales as shown in region R of Figure 1. Since the textured yarn has a low dtex it is not very noticeable in these regions.
The tape 50 shown in Figure 2 includes a ground fabric including two series of weft loops 51,52 which are laid-in 180° out-of-phase so as to be in opposition. The terminal ends of the weft loops define the opposed edges 54,55 of the tape. The weft loops 51,52 are preferably formed from a relatively flexible yarn such as 2 x 2 fold 78 dtex polyamide giving a total dtex value of 312. A plurality of straight wales 60 of knitted stitches are provided for holding the weft loops together. The wales 60 are preferably knitted from a single end of 2 fold 78 dtex polyamide. The weft loops are preferably laid-in on consecutive courses so as to provide a dense ground fabric.
Since the ground fabric is formed from flexible yarns it has a relatively flexible handle which makes it suitable for fixing onto garments without causing excessive stiffening of the garment.
In addition to creating a dense ground fabric, it is desirable for the loop pile to be in the form of a mat of tangled loops which extends continuously across substantially the entire width of the ground fabric and along the length of the tape and for the mat to have a greater density than that of the embodiment having a monofilament ground fabric.
Such a continuous expanse of the mat of tangled loops forms a dense surface layer on the ground fabric and serves to shield the ground fabric from penetration by the hook pile of the male tape. Accordingly, with such a construction it is difficult for the male hooks of the male tape to engage the yarns of the ground fabric and thereby cause damage or deformation.
To increase the density of loops, the wales of the ground fabric are preferably closely spaced, typically about 1 mm apart and are each supplied with a textile yarn end. Thus a very dense mat of tangled loops is provided.
Preferably during knitting of the wales 60 an elastomeric yarn such as Lycra (RTM) or rubber is trapped within the stitches of wales 60 in order to elasticate the tape in the warp direction. The rubber is about 40 gauge, or if Lycra is used, a dtex value of about 1240 is chosen. Thus on leaving the knitting machine the fabric contracts in the warp direction shortening the distance between adjacent legs of the weft loop and so helps to increase the density of the mat by effectively folding each float 17. Accordingly, in this embodiment it has been found that it is sufficient to knit-in one end of knit-deknit yarn of 220 dtex per wale. Preferably the length of floats for creating the mat are longer than the maximum distance inbetween the adjacent legs of the weft loops after stretching of the tape longitudinally. In this way the mat of tangled loops still project above the surface of the tape after fully stretching the tape. This is particularly useful in application of the band where the male tape engages the loop pile tape when in a stretched condition. Such an application is schematically illustrated in Figure 3, wherein an elasticated band of the construction illustrated and described in relation to Figure 2 has a portion of male tape 70 attached to one end to enable the band to be wrapped around an object and serves to form a continuous band by the male tape engaging with the loop pile tape. Such a band is useful as for example a garter.
As indicated above for the embodiments of both Figures 1 and 2, the textured yarn is preferably a knit-deknit yarn. The yarn preferably has a dtex value between 200-220 dtex and is a multifilament yarn having preferably between 8 - 10 filaments. The dtex value given is that of the yarn prior to the knit-deknit treatment.
The mat of tangled loops is preferably less than 3 mm deep, more preferably less than about 2 mm and is more preferably about 1 mm deep. It will be appreciated therefore that the mat of tangled loops has a close cropped appearance and is therefore similar in appearance to woven tapes without any further operation such as brushing.

Claims

A method of producing a warp knitted tape (10) having a loop pile, the method including the steps of knitting a ground fabric by knitting a plurality of straight wales (12) from wale forming yarn and during knitting of the wales laying-in across said plurality of wales (12) on selected courses at least one weft yarn (14), characterised in that during knitting of the ground fabric a textured yarn (16) is knitted-in along selected wales (12), the textured yarn (16) being floated across adjacent wales or courses at selected locations to define a float (17) on the surface of the ground fabric at said selected locations, the textured yarn (16) being knitted-in under tension and permitted to relax in the region of the floats (17) after knitting in order to produce a loop pile comprising a mat of tangled loops.
A method according to claim 1, wherein the textured yarn (16) is knitted-in along selected wales and at selected locations floated across to an adjacent wale to create a float (17), the textured yarn being knitted-in on at least two consecutive courses in between said selected locations.
A method according to claim 1 or 2, wherein the textured yarn (16) is floated across a loop forming finger so as to have a length greater than the distance between adjacent stitches at each end of the float (17).
A method according to claim 3, wherein the finger creates a loop of about 3-5mm in height before relaxation of the loop.
A method according to any preceding claim wherein the textured yarn (16) is knitted-in to define discrete mat areas spaced along and/or across the width of the tape.
A warp knitted tape (10) having a loop pile, the tape (10) comprising a warp knitted ground fabric, characterised in that a textured yarn (16) is knitted-in to produce floats (17) of textured yarn (16) on the surface of the ground fabric, the floats (17) of textured yarn defining a loop pile comprising a mat of tangled loops.
A tape according to claim 5, wherein the mat has a depth less than 3mm.
A tape according to claim 6 or 7, including discrete mat areas spaced along and/or across the width of the tape (10).
A tape according to claims 6, 7 or 8, wherein the mat extends continuously across substantially the entire width of the tape (10) and along the length of the tape (10) and is of a density sufficient to shield the ground fabric from penetration by a hook pile of a male touch and close tape.
A tape according to any of claims 6 to 9, wherein the textured yarn (16) is a knit-de-knit yarn.