GB2238061A

GB2238061A - Protective braided sleeve

Info

Publication number: GB2238061A
Application number: GB8925220A
Authority: GB
Inventors: Jody Keith Burnett; Alan William Atkinson
Original assignee: T&N Technology Ltd
Current assignee: Federal Mogul Technology Ltd
Priority date: 1989-11-08
Filing date: 1989-11-08
Publication date: 1991-05-22
Anticipated expiration: 2009-11-08
Also published as: GB2238061B; GB8925220D0

Abstract

A textile braided sleeve e.g. for electric wiring or fuel pipes is helically wrapped with a strip of heat reflecting material, said material being attached to the braid along only a relatively narrow zone extending lengthwise of the strip and the pitch of said wrapping being such as to develop an overlap between successive turns whilst at the same time attaching it to the braid along a spiral path which is substantially parallel to one of the braiding directions, the foil being attached to the braid and not to itself. The heat reflecting material is preferably a metal foil or a metallised polymer film.

Description

Improved braids This invention relates LO hollow textile braids used as sleeving to protect electrical wiring and/or fuel pipes against radiant heat. Such braids exhibit good flexibility. They can be bent around relatively small radii without kinking or serious loss of cross-sectional area. Also they can be stretched and/or compressed axially, with a corresponding change in diameter. However, it is usually necessary to enhance the heat reflecting properties of the braid in order to achieve satisfactory protection.

For example, the braid may be covered with a polymer layer containing metallic particles, especially flakes. This maintains much of the flexiblity, but the heat reflectivity is not significantly improved. Another known form of enhancement is the application of a layer of aluminium foil or aluminised polymer film to a flat, woven fabric which is then folded into a tubular configuration.

The latter is thereafter fixed by stitching longitudinally of the tube. This however leads to a substantial loss of flexibility.

Foil can also be wrapped around a tubular braid, before or after installation. However, such uses of foil result in a relatively inflexible product, or one in which the braid bursts out of the foil on flexing.

It is an object of the present invention to at least mitigate these problems.

According to this invention, a textile braid is helically wrapped with at least one strip of heat reflecting material, said strip being attached to the braid along only a narrow zone extending lengthwise of the strip, the pitch of said wrapping being such as to develop an overlap between successive turns whilst at the same time attaching it to the braid along a spiral path which is substantially parallel to one of the braiding directions, the foil being attached to the braid and not to itself.

Braiding direction" in this present context refers to the natural spiral lie of the yarns in the braid. This is a feature which is readily visible in conventional braids.

The heat reflecting material is preferably a metal foil or a metallised polymer film. Preferably a plurality of strips are applied substantially simultaneously.

It has been found that by attaching a strip to the braid only along a narrow region or zone corresponding to the braiding direction (the natural lie of the yarns in the braid), it is possible to maintain good flexibility without unduly compromising the integrity of cover. This is an improvement on prior art methods such as laminating foil completely onto thc braid, or onto a woven cloth which is subsequently formed into a tube. Whilst both of these achieve complete cover, it is at the expense of a substantial loss of flexibility.

A particularly preferred heat reflecting strip is an aluminised polyester foil strip, because such material has excellent strength and is not readily ruptured by flexing, unlike pure aluminium foils. For a braid of 15mm nominal diameter, a strip width of the order of 12-14mm is satisfactory when wound to give around 50 percent overlap of successive turns. The relatively narrow attachment zone may be constituted by a nitrile phenolic resin adhesive of the heat activated kind. It may be applied to one side of the foil strip as a continuous, narrow stripe, or it may be applied as a discontinuous line of adhesive spots. The adhesive zone may be along one edge of the strip, or between one edge and the centre thereof, subject to achieving satisfactory overlap and adhesion to the braid, as mentioned above, rather than to itself.

Other attachment methods such as stitching, fusion bonding, pinning, needling, rivetting and the like are also possible.

Braids treated according to this invention can be bent around relatively small radii, but this can lead to the formation of small folds of reflective material protruding from the otherwise smooth surface. This has only a limited effect on the heat reflecting properties, but it can in some circumstances make the product less aesthetically acceptable as well as slightly more vulnerable to abrasion damage. Where necessary, the effect of this can be minimised by providing an outer layer of a relatively open braid, or knitted mesh. Typically, the apertures between the yarns of such an ancillary layer would constitute at least 50% of the overall surface area. Suitable ancillary layer materials include glass fibre and metal wire. The use of an ancillary layer reduces the extent to which folds, etc. can protrude, without significantly reducing flexibility.

In order that the invention be better understood, it will now be described by reference to the following examples Example 1. A glass fibre braid of nominal diameter 15mm consisting of 27 ends in each braiding direction was wrapped simultaneously with six 14mm wide strips of 12um thick polyester film that had been coated on both sides with aluminium. Each strip was attached to the braid by a 2mm wide band of a nitrile phenolic adhesive, this band being located approximately 2mm from one edge of the strip. The strips were applied so as to lie parallel to one of the yarn directions in the braid. Adjacent strips were overlapped by about 30% cf their width. The wrapped braid remained highly flexible and could be bent around relatively small radii without excessive kinking. It also retained much of its ability to be axially compressed or stretched.

Example 2. The previous example was repeated with the adhesive applied as a row of spots instead of a stripe.

The spots were about 2mm in diameter and about 8mm apart.

The resultant product was even more flexible that that of Example 1.

Claims

CLAIMS:

1. A textile braid helically wrapped with a strip of heat reflecting material, said material being attached to the braid along only a relatively narrow zone extending lengthwise of the strip, the pitch of said wrapping being such as to develop an overlap between successive turns whilst at the same time attaching it to the braid along a spiral path which is substantially parallel to one of the braiding directions, (as defined), the foil being attached to the braid and not to itself.

2. A textile braid according to claim 1 wherein the heat reflecting material . is a metal foil or a metallised polymer film.

3. A textile braid according to claim 1 or claim 2 wherein the strip is attached by means of adhesive.

4. A textile braid according to claim 3 wherein the adhesive is applied as a continuous narrow stripe lengthwise of the strip.

5. A textile braid according to claim 3 wherein the adhesive is discontinuous lengthwise of the strip.

6. A textile braid according to any of claims 1-5 wherein the strip is a metal coated polyester film.

7. A textile braid according to any of claims 2-6 wherein the metal is aluminium.

8. A textile braid according to any of claims 2-7 wherein the adhesive is a nitrile - phenolic heat activated adhesive.

9. A textile braid according to any of claims 1-8 having an outer layer of a open braid or knitted mesh applied on top of the heat reflecting surface, the outer layer construction being such that at least 50% of its surface area is constituted by apertures.

10. A textile braid substantially as hereinbefore described with reference to and as illustrated b Examples 1 and 2.