A THREAD, FABRIC PRODUCED FROM THAT THREAD AND METHOD FOR MANUFACTURING THE THREAD AND FABRIC

This invention relates to a thread and a fabric manufactured from that thread. The invention also relates to a method for manufacturing that thread and fabric. The fabric is particularly applicable for use in the manufacture of internal and external blinds. It will therefore be convenient to hereinafter disclose the invention in relation to this exemplary application, although it is to be appreciated that the invention is not limited thereto. Indeed, the invention may be used in a variety of other applications including, for example, shade cloth providing shade and other protection to an underlying area or space, and privacy applications on fences, tennis court fences and temporary worksite fences .

Existing fabric for use in the manufacture of internal and external blinds is typically manufactured in one of several general forms, including polyvinylchloride (PVC) coated polyester, knitted high-density polyethylene (HDPE) tape or monofilament, woven HDPE tape, silicon coated glass or Teflon (polytetrafluroethylene or PTFE) coated glass.

PVC coated polyester is particularly popular, because of its aesthetic appeal, its relatively cheap manufacturing cost and because it is relatively robust. Unfortunately, however, the PVC coating can undesirably separate from the polyester during manufacture thereby undesirably creating a relatively high rejection rate.

Knitted HDPE tape/filament is extensively used in the manufacture of blinds. However, HDPE products generally do not have the same degree of aesthetic appeal as polyester coated PVC.

Silicon coated glass forms only a very small portion of the blind market. It has a much higher tensile strength than polyester; however, being glass is brittle. To overcome this, the fibres are made to a very small diameter but are still subject to damage from repeated flexing.

Silicon coated glass is generally less expensive than the Teflon coated glass, however the Teflon has better "self cleaning" properties. Further, Teflon coated glass is generally difficult to handle and transport in large pieces because when sharply folded the Teflon coating visibly "bruises". Like silicon coated glass, Teflon coated glass forms only a very small portion of the blind market.

It would be desirable to provide a fabric that addresses one or more of the disadvantages referred to above with respect to existing fabrics.

The above discussion of materials, articles and the like is included in this specification solely for the purpose of providing a context for the present invention. It is not suggested or represented that any of these matters formed part of the prior art base or were common general knowledge in the field relevant to the present invention as it existed in Australia or elsewhere before the priority date of each claim of this application.

According to a broad aspect of the present invention, there is provided a thread, the thread including a substrate and a coating applied to the substrate. Each of the substrate and coating include polypropylene.

The substrate may be of any suitable thickness and cross-sectional shape. Most preferably, however, the substrate has an approximately circular cross- sectional shape to allow for the coating to be applied generally evenly. The coating may also be of any suitable thickness and cross-sectional shape.

In a preferred form, the substrate of the thread includes a plurality of longitudinally extending polypropylene fibres. It is to be appreciated, however, that the substrate may include a single longitudinally extending polypropylene fibre.

Preferably, the coating is bonded to the substrate.

The present invention is also directed to a fabric including a plurality of threads of the type referred to above. Each of the plurality of threads includes a substrate and a coating applied to the substrate. Each of the substrate and coating include polypropylene.

In a preferred form, the fabric, includes a plurality of longitudinally and transversely extending threads. The fabric may be woven so as to have an open mesh appearance.

In a preferred form, the threads are woven, with at least some of the longitudinally extending threads stentered or bonded to at least some of the transversely extending threads. The fabric may incorporate any practical weave pattern.

For assistance in arriving at an understanding of the present invention, an example of a fabric according to the present invention is illustrated in the attached photograph. The preceding description of a thread, a fabric and method of manufacture may be read with reference to that photograph. However, as the photograph illustrates one example only, its particularity is not to be understood as superseding the generality of the preceding description.

Figure 1 is a photographic side view of a piece of one example fabric incorporating the present invention.

Referring to Figure 1 , there is illustrated a fabric 10 manufactured from a plurality of individual threads 12 (only some of which are numbered). Each thread 12 includes a substrate (not visible) and a coating (not visible) applied to the substrate. The coating is bonded to the substrate.

The fabric 10 includes a plurality of longitudinally extending threads 14 (only some of which are numbered) and transversely extending threads 16 (only some of which are numbered). The longitudinally extending threads 14 and transversely extending threads 16 are woven in a manner providing an open mesh appearance.

The substrate of each of the threads 12 has an approximately circular cross- sectional shape to assist in the application of a generally even coating to the substrate. The cross-sectional diameter of each thread 12 is approximately 0.65mm. However, it is to be appreciated that the thread may be of any suitable thickness and cross-sectional shape. Likewise, each of the substrate and coating may be of any suitable thickness and cross-sectional shape. In the illustrated embodiment, the cross-sectional thickness of each thread is composed of approximately 75% coating and 25% substrate.

The substrate of each thread 12 includes a plurality of longitudinally extending polypropylene fibres (not visible). The plurality of longitudinally extending fibres may however be replaced with a single longitudinally extending fibre if desired.

The substrate may be manufactured on conventional polypropylene spinning and twisting equipment. Once manufactured, the substrate may then be coated using conventional extrusion equipment, similar to that used for wire or cable coating. The coated fabric 10 is woven on rapier looms, but other types of looms such as projectile or air-jet looms can also be used.

Resin is used in the manufacture of the coating. The resin is a co-polymer of polypropylene, ethylene and synthetic rubber. The rubber content is approximately 40%, providing the coating with, in relative terms, excellent softness and flexibility.

The longitudinally extending threads 14 and transversely extending threads 16 are stentered, or bonded, at each of their respective cross-points. The stentering process used in the production of the fabric 10 utilises a stentering machine (not illustrated) having sixteen heating chambers and a length of approximately 25 metres. Fabric to be stentered is fed through the heating chambers at a rate of approximately 10 metres/minute with operating temperatures of the chambers ranging from about 100O to about 120 ⁰ C. The specific chamber configuration, operating temperatures and feed rates may be

selected to optimize the stentoring process for a given fabric, and so it is to be appreciated that the values stated above may be varied if required. The threads 12 include a wax additive which, together with a unique spin finish, assists in preventing the fabric 10 from wicking. Details of a wax additive of the type contemplated in the present application are included in the applicant's co- pending application PCT/AU2004/001828, the entire details of which are incorporated herein be reference.

Advantageously, in practical terms it is extremely difficult to separate the substrate and coating of the present invention, thereby creating a particularly durable fabric. Further, the inventive thread and fabric generally doesn't absorb moisture, doesn't discolour, is mildew and UV resistant, and so is particularly useful for exterior use. The fabric is particularly suitable for use in both internal and external blind applications. However, the fabric may also be used in, for example, shade cloth and privacy applications such as when applied to fences, tennis court fences and temporary worksite fences.

Further, the inventive thread and fabric is potentially more cost effective to manufacture and is lighter weight and therefore easier to handle and transport when compared to existing exterior use fabrics. It is also potentially recyclable.

Another advantage of the inventive thread and fabric is that they generally have a density < 1 , and so may also be used for, for example, floating pool cover or other floating applications.

Finally, it is to be understood that various alterations, modifications and/or additions may be introduced into the construction and arrangement of the parts previously described without departing from the spirit or ambit of this invention.

Without limiting the claim scope that may be sought in any Australian or overseas patent application claiming priority from the present application, the following claims are provided.