GB1568702A

GB1568702A - Articles comprising or consisting of an internally reinforced elastomeric layer

Info

Publication number: GB1568702A
Application number: GB4709/79A
Authority: GB
Original assignee: Goodyear Tire and Rubber Co
Current assignee: Goodyear Tire and Rubber Co
Priority date: 1973-05-08
Filing date: 1976-12-15
Publication date: 1980-06-04

Description

(54) IMPROVEMENTS IN AND RELATING TO ARTICLES COMPRISING OR CONSISTING OF AN INTERNALLY REINFORCED ELASTOMERIC LAYER (71) We, THE GOODYEAR TIRE & RUBBER COMPANY, a Company organised and existing under the laws of the State of Ohio, United States of America, of Akron, Ohio 44316, United States of America, 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 perform ed, to be particularly described in and by the following statement: This invention relates to articles comprising or consisting of a reinforced elastomeric layer, and more especially to conveyor belts.

Textile reinforced conveyor belts are conven tionally made either by assembling numerous suc cessive layers of rubberised fabric and rubber and then vulcanizing them together, or by using a single ply of fabric covered with elastomeric or thermoplastic material possibly on one but usually on both sides. The present invention is concerned with this latter type of conveyor belt, which is usually referred to as a single-ply belt.

In such a single-ply belt the design of fabric is particularly important. Thus, the fabric must have enough transverse rigidity to support the load without sagging but also enough flexibil ity so that the belt will "trough" between idler rollers. Also, it must have enough longitudinal rigidity to prevent spillage between such idler rollers but on the other hand not so much as to inhibit flexure of the belt for example over the drive rollers and idlers. The belt must also poss ess enough tensile strength to withstand the tensions imposed on it by the drive without ex cessive stretching Moreover, it should be pref erably be able to withstand impact by large and/or sharp pieces of material, and should possess tear resistance both to tearing by conveyed sharp objects and to tearing at the metallic fasteners where the ends of the belt are joined. This latter location should also resist "combing out" of weft material from the longitudinal warp threads.

Conventional square-woven fabrics are unsuitable for this type of reinforcement. Prior proposals have included fabrics where a binder thread holds together warp and weft.

Our UK Patent Specification No. 1450142 describes the construction of a conveyor belt or like elastomer article in which there is provided an internal reinforcement in the form of a stich-bonded fabric possessing a plurality of parallel warp threads and a plurality of parallel weft threads united by a plurality of parallel stiching threads, wherein the warp and weft threads are formed in a yarn comprising a plurality of continuous filaments and having not more than two twists per inch, in order to min imise their extensibility and improve bonding of the elastomer to the fabric.

Specification 1450142 goes on to specify that the weft threads may be located on one side only of the warp threads and that the stitch ing threads may extend longitudinally to unite the warp threads. Moreover, the weft threads can be angled at up to 150 to the transverse dir ection, and can in fact be provided as two sup erimposed sets of parallel weft threads each at the same angle to the transverse direction but in opposite directions so as to form an overlap ping system.

Specification 1450142 is concerned with systems in which the warp and weft threads have not more than two twists per inch. We have discovered that the advantages presented and described in Specification 1450142 are exhibited at somewhat higiler degrees of twist, up to 10 turns per inch, up to 10 turns per inch, as described and claimed in our co-pending Application No.

11472/76 serial No. 1568701 from which the present application is divided.

The present invention consists in an article comprising or consisting of an internally reinforced elastomeric layer, wherein the internal reinforcement is a stitch-bonded fabric possessing at least one warp layer comprising a plurality of parallel warp threads, and at least one weft layer comprising a plurality of parallel weft threads, the said fabric having at least three said warp and weft layers, the said warp and weft layers being united by a plurality of parallel stitching threads.

The other preferred features of our earlier invention outlined above can also be utilised in conjunction with the present invention.

It is preferred for the stitching thread to run in the warp direction, forming a tricot stitch by interlocking of adjacent loops of stitching thread.

This invention is applicable to stitch-bonding fabrics whatever the degree of twist in the yarns of the warp and weft. Preferably however. the degree of twist in the warp and weft threads is not more than 10 turns per inch (as described above), as higher levels of twist tend to reduce penetration of adhesive. and hence the adhesion, and it may be advantageous to use only those fabrics where the degree of yarn twist is not more than two per inch, as described in our specification 1450142.

It is most valuable to use a fabric having transverse (weft) yarns or threads on both sides of a single set of warp threads.

In the fabric of the present invention it may be advantageous to utilise a fibre flock filler layer between the various warp and/or weft layers Such a layer can be totally replaced or supplemented by a layer of woven fabric.

The fiction of such a layer of filler material (either as loose-carded fibres or as a woven fabric) is to protect the warp threads from the effect of impact. Moreover, the filler layer can be used to move the weft layer further from the neural axis of the belt to increase the lateral stiffness of the fabric.

The warp threads, the weft threads, the fibre layer, or any intermediate woven fabric layer, can each be made from one or more of polyester, polyamide, cotton, aromatic polyamide, acrylic fibre, polyvinyl-alcohol fibre, cellulose fibre or glass fibre. Various combinations are possible; thus, for instance it is possible to have warp threads as a mixture of polymers, or to have warp threads as one polymer and to have the weft threads as another and possibly the filler layer fibres or fabric as a third.

The invention will be further described with reference to the accompanying drawings in which: Figure 1 is an idealised section through one form of reinforcement fabric for a conveyor belt according to the invention, and Figure 2 is an idealised section through another form of reinforcement fabric.

In the fabric shown in Figure 1, there is provided a top layer of weft threads 1 and a bottom layer of weft threads 3 staggered in relation to one another on either side of a layer of warp threads 2. These warp threads and weft threads are not interwoven, for reasons as set forth in Specification 1450142, but are instead united by stitching threads 6 which run in the warp direction and pass vertically through the weft thread assembly, interlocking on adjacent loops as shown at 4 to provide a Tricot stitch. For ease of illustration this is only shown diagrammatically in the figure.

Figure 2 is generally similar to Figure 1 and the various common features as shown with the same reference numbers. However, there is add- itionally provided a layer 5 of carded textile fibres laying between the upper weft layer 1 and the warp layer 2. This shields the warp layer from impact and increases the lateral stiffness of the fabric.

The warp and weft threads are of yarn comprising a plurality of continuous filaments and possessing more than two but not more than ten twists per inch. They can be "singles" yarns or plied or multiple yarns. The stitching thread is for example, 420 denier nylon. The weft threads may be angled at up to 15 to the transverse direction. The fabric may comprise two superposed sets of parallel weft threads each angled at the same angle to the transverse direction but in opposite directions so as to fonn an overlapping system of weft threads, For example, each set of weft threads may extend to the edge of the fabric and return at the same angle but in the opposite direction to constitute another set of threads.

The invention is applicable to articles in the form of conveyor belts, or in the form of a strip of reinforcing material. The elastomer to which the reinforcing fabric is bonded may be a natural or synthetic rubber or a plasticised or unplasticised thermoplastic material e.g. plasticised polyvinyl chloride.

WHAT WE CLAIM IS: 1. An article comprising or consisting of an internally reinforced elastomeric layer, wherein the internal reinforcement is a stitch-bonded fabric possessing at least one warp layer comprising a plurality of parallel warp threads, and at least one weft layer comprising a plurality of parallel weft threads, the said fabric having at least three said warp and weft layers, the said warp and weft layers being united by a plurality of parallel stitching threads.

2. An article as claimed in claim 1, wherein the warp and weft threads are formed in a yarn comprising a plurality of continuous filaments and possessing only up to ten twists per inch.

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

Claims

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

Specification 1450142 is concerned with systems in which the warp and weft threads have not more than two twists per inch. We have discovered that the advantages presented and described in Specification 1450142 are exhibited at somewhat higiler degrees of twist, up to 10 turns per inch, up to 10 turns per inch, as described and claimed in our co-pending Application No.

11472/76 serial No. 1568701 from which the present application is divided.

The present invention consists in an article comprising or consisting of an internally reinforced elastomeric layer, wherein the internal reinforcement is a stitch-bonded fabric possessing at least one warp layer comprising a plurality of parallel warp threads, and at least one weft layer comprising a plurality of parallel weft threads, the said fabric having at least three said warp and weft layers, the said warp and weft layers being united by a plurality of parallel stitching threads.

The other preferred features of our earlier invention outlined above can also be utilised in conjunction with the present invention.

It is preferred for the stitching thread to run in the warp direction, forming a tricot stitch by interlocking of adjacent loops of stitching thread.

This invention is applicable to stitch-bonding fabrics whatever the degree of twist in the yarns of the warp and weft. Preferably however. the degree of twist in the warp and weft threads is not more than 10 turns per inch (as described above), as higher levels of twist tend to reduce penetration of adhesive. and hence the adhesion, and it may be advantageous to use only those fabrics where the degree of yarn twist is not more than two per inch, as described in our specification 1450142.

It is most valuable to use a fabric having transverse (weft) yarns or threads on both sides of a single set of warp threads.

In the fabric of the present invention it may be advantageous to utilise a fibre flock filler layer between the various warp and/or weft layers Such a layer can be totally replaced or supplemented by a layer of woven fabric.

The fiction of such a layer of filler material (either as loose-carded fibres or as a woven fabric) is to protect the warp threads from the effect of impact. Moreover, the filler layer can be used to move the weft layer further from the neural axis of the belt to increase the lateral stiffness of the fabric.

The warp threads, the weft threads, the fibre layer, or any intermediate woven fabric layer, can each be made from one or more of polyester, polyamide, cotton, aromatic polyamide, acrylic fibre, polyvinyl-alcohol fibre, cellulose fibre or glass fibre. Various combinations are possible; thus, for instance it is possible to have warp threads as a mixture of polymers, or to have warp threads as one polymer and to have the weft threads as another and possibly the filler layer fibres or fabric as a third.

The invention will be further described with reference to the accompanying drawings in which: Figure 1 is an idealised section through one form of reinforcement fabric for a conveyor belt according to the invention, and Figure 2 is an idealised section through another form of reinforcement fabric.

In the fabric shown in Figure 1, there is provided a top layer of weft threads 1 and a bottom layer of weft threads 3 staggered in relation to one another on either side of a layer of warp threads 2. These warp threads and weft threads are not interwoven, for reasons as set forth in Specification 1450142, but are instead united by stitching threads 6 which run in the warp direction and pass vertically through the weft thread assembly, interlocking on adjacent loops as shown at 4 to provide a Tricot stitch. For ease of illustration this is only shown diagrammatically in the figure.

Figure 2 is generally similar to Figure 1 and the various common features as shown with the same reference numbers. However, there is add- itionally provided a layer 5 of carded textile fibres laying between the upper weft layer 1 and the warp layer 2. This shields the warp layer from impact and increases the lateral stiffness of the fabric.

The warp and weft threads are of yarn comprising a plurality of continuous filaments and possessing more than two but not more than ten twists per inch. They can be "singles" yarns or plied or multiple yarns. The stitching thread is for example, 420 denier nylon. The weft threads may be angled at up to 15 to the transverse direction. The fabric may comprise two superposed sets of parallel weft threads each angled at the same angle to the transverse direction but in opposite directions so as to fonn an overlapping system of weft threads, For example, each set of weft threads may extend to the edge of the fabric and return at the same angle but in the opposite direction to constitute another set of threads.

The invention is applicable to articles in the form of conveyor belts, or in the form of a strip of reinforcing material. The elastomer to which the reinforcing fabric is bonded may be a natural or synthetic rubber or a plasticised or unplasticised thermoplastic material e.g. plasticised polyvinyl chloride.

WHAT WE CLAIM IS: 1. An article comprising or consisting of an internally reinforced elastomeric layer, wherein the internal reinforcement is a stitch-bonded fabric possessing at least one warp layer comprising a plurality of parallel warp threads, and at least one weft layer comprising a plurality of parallel weft threads, the said fabric having at least three said warp and weft layers, the said warp and weft layers being united by a plurality of parallel stitching threads.
2. An article as claimed in claim 1, wherein the warp and weft threads are formed in a yarn comprising a plurality of continuous filaments and possessing only up to ten twists per inch.
3. An article as claimed in claim 2, wherein

the yarn has not more than two twists per inch.
4. An article as claimed in claim 1, 2 or 3 wherein a warp layer is disposed between two weft layers.
5. An article as claimed in any preceding claim wherein the weft threads are angled at up to 15 to the transverse direction.
6. An article as claimed in any preceding claim wherein the stitching thread runs in the warp direction.
7. An article as claimed in any preceding claim in which adjacent loops of the stitching thread are interlocked to form a Tricot stitch.
8. An article as claimed in any preceding claim wherein a fibrous filler layer is provided between at least two of the said warp and weft layers.
9. An article as claimed in any one preceding claim in the form of a conveyor belt.
10. An article as claimed in any of claims 1 tc, 8 in the form of a strip of reinforcing material
II. An article as claimed in claim 1 and substantially as herein described.
12. An article as claimed in any preceding claim wherein the elastomer is a natural or synthetic rubber or a plasticised or unplasticised thermoplastic material.