Mcqueen, Alisdair (Carrington Performance Fabrics Limited Calder Works Thornhill Road Dewsbury West Yorkshire WF12 9QQ, GB)
| 1. | A method of coating a wire fabric comprising the steps of: coating a first surface of the wire fabric with a first coating of a hot melt polymer ; coating a second, opposed surface of the wire fabric with a second coating of the hot melt thermoplastic polymer such that the two coatings bond to each other; the coatings being sufficient to encase the wire fabric therein, and to fill any gaps in the structure of the wire fabric, thereby providing a monolithic coated wire fabric. |
| 2. | A method according to claim 1 in which the first and second coatings are applied by lamination. |
| 3. | A method according to claim 2 in which the step of coating the second surface of the wire fabric comprises applying a film of the hot melt thermoplastic polymer to the second surface using rollers. |
| 4. | A method according to claim 2 or claim 3 in which the step of coating the first surface of the wire fabric comprises coating a carrier substrate with the hot melt polymer, bringing the coated carrier substrate into contact with the first surface of the wire fabric, and removing the carrier substrate from the first surface. |
| 5. | A method according to claim 4 in which the carrier substrate is removed after the wire fabric is coated with the second coating. |
| 6. | A method according to any of claims 3 to 5 in which the carrier substrate is coated by applying a film of the hot melt polymer to the second surface using rollers. |
| 7. | A method according to any of the previous claims in which the first coating is of a weight in the range of 150 to 300 go2. |
| 8. | A method according to any of the previous claims in which the second coating is of a weight in the range 600 to 900 gum2. |
| 9. | A method according to any of the previous claims in which a third coating of the hot melt polymer is applied as a top coat. |
| 10. | A method according to claim 9 in which the third coating is of a weight in the range 70 to 200 gum2. |
| 11. | A method according to any of the previous claims in which a lacquer layer is applied to a surface of the coated wire fabric. |
| 12. | A method according to any of the previous claims in which the wire fabric comprises woven, knitted or twisted wires. |
| 13. | A method according to any of the previous claims in which the wire fabric is stab resistant. |
| 14. | A method according to claim 12 or claim 13 in which the wires are woven as warp and weft threads. |
| 15. | A method according to any of the previous claims in which the hot melt thermoplastic polymer is selected from the list urethanes, vinyl chlorides, olefins, PVDF or the like. |
| 16. | A coated wire fabric comprising a wire fabric coated with a holt melt polymer so as to encase the wire within the polymer and to fill any gaps in the structure of the wire fabric, thereby providing a monolithic coated wire fabric. |
| 17. | A coated wire fabric according to claim 16 further comprising a lacquer layer. |
| 18. | A coated wire fabric according to claim 16 or claim 17 in which the hot melt thermoplastic polymer is selected from the list urethanes, vinyl chlorides, olefins PVDF or the like. |
| 19. | A coated wire fabric according to any of claims 16 to 18 in which the wire fabric is stab resistant. |
| 20. | A coated wire fabric according to any of claims 16 to 19 in which the wire fabric comprises woven, knitted or twisted wires. |
| 21. | A coated wire fabric according to claim 20 in which the wires are woven as warp and weft threads or warp or weft threads alone. |
| 22. | A coated wire fabric according to any of claims 16 to 21 in which the wire fabric comprises a plurality of steel cords, each of said steel cords comprising a longitudinal axis and two or more steel filaments, each of said steel filaments forming a twisting angle with the longitudinal axis of said steel cord, said steel cords having two or more such twisting angles which are substantially different from each other. |
| 23. | Use of a coated wire fabric according to any of claims 16 to 22 as a curtain or shutter. |
| 24. | Use according to claim 23 in which the coated wire fabric comprises a curtain acting as a closure for a vehicle. |
| 25. | Use of a coated wire fabric according to any of claims 16 to 22 in a marine application. |
| 26. | Use according to claim 25 in which the coated wire fabric forms part of, or comprises, a raft, oil boom, cargo net, reinforcing barrier or hovercraft skirt. |
| 27. | Architectural use of a coated wire fabric according to any of claims 16 to 22. |
| 28. | Use according to claim 27 in which the coated wire fabric forms part of, or comprises walling, roofing, a tent or a marquee. |
| 29. | A flexible storage tank comprising a coated wire fabric according to any of claims 16 to 22. |
| 30. | A flexible fuel tank according to claim 29. |
| 31. | A flexible water storage tank according to claim 29. |
| 32. | A cargo hold comprising a coated wire fabric according to any of claims 16 to 22. |
European Patent EP 0 879 001 discloses a stab resistant insert which comprises a fabric made from a plurality of steel cords, each cord having a number of steel filaments which form a twisting angle with a longitudinal axis of the cord. The steel cords together have two or more twisting angles which are substantially different from each other. The resistance of the steel filaments to a stabbing blow from a knife or like instrument is dependent on the angle between the direction of the stabbing motion and filament, and is smallest when this angle is 90° By providing a number of different twisting angles, it is possible to ensure that, irrespective of the direction of the stabbing motion, at least some of the steel cords are not at 90° with respect to the stabbing motion and therefore provide adequate stab resistance.
The stab resistant fabric is intended to be used as an insert in protective textiles such as vests. It is a disadvantage that the stab resistant steel fabric has to be used in this way: it would be advantageous if a coated stab resistant fabric could be manufactured, so that the stab resistant fabric
forms in integral part of a protective sheeting, curtain or like material.
However it is very difficult to provide such a protective sheeting, since it is very difficult to coat the stab resistant fabric, owing to the relatively large gaps that exist between the warp and weft of the fabric. In other words, it is difficult to fill the gaps in a coating process.
The present invention overcomes this problem, and provides a method for coating stab resistant fabrics of the type disclosed in EP 0 879 001. It should be noted that the invention is not limited to stab resistant fabrics of EP 0 879 001: rather, other forms of stab resistant wire fabrics- and even non stab resistant wire fabrics-might be coated using the method. The present invention also provides polymer coated wire fabrics, and numerous uses therefor.
According to a first aspect of the invention there is provided a method of coating a wire fabric comprising the steps of: coating a first surface of the wire fabric with a first coating of a hot melt thermoplastic polymer ; coating a second, opposed surface of the wire fabric with a second coating of the hot melt thermoplastic polymer such that the two coatings bond to each other; the coatings being sufficient to encase the wire fabric therein, and to fill any gaps in the structure of the wire fabric, thereby providing a monolithic coated wire fabric.
In this way, it is possible to completely coat the wire fabric, filling up any gaps in the wire structure, even if these gaps are relatively large ones.
Advantageously, the first and second coatings are applied by lamination. The step of coating the second surface of the wire fabric may comprise applying a film of the hot melt polymer to the second surface using rollers. Calendar rollers can be used, and it is advantageous that single set of calendar rollers can be used to perform all of the required coating steps.
The step of coating the first surface of the wire fabric may comprise coating a carrier substrate with the hot melt polymer, bringing the coated carrier substrate into contact with the first surface of the wire fabric, and removing the carrier substrate from the first surface. The carrier substrate may be removed after the wire fabric is coated with the second coating.
The carrier substrate may be coated by applying a film of the hot melt polymer to the second surface using rollers. These can be the same calendar rollers that can be used to coat the second surface of the wire fabric.
The first coating may be of a weight in the range 150 to 300 gum-2.
The second coating may be of a weight in the range 600 to 900 gm-2.
A third coating of the hot melt polymer may be applied as a top coat.
The third coating may be of a weight in the range 70 to 200 gm~2.
A lacquer layer may be applied to a surface of the coated wire fabric.
The wire fabric may comprise woven, knitted or twisted wires and may be in any predetermined woven or knitted structure.
Wire fabrics may be stab resistant.
The wires may be woven as warp and weft threads or warp or weft threads alone.
The hot melt thermoplastic polymer may be selected from the list urethanes, vinyl chlorides, olefins, PVDF or other suitable polymers.
According to a second aspect of the invention there is provided a coated wire fabric comprising a wire fabric coated with a hot melt thermoplastic polymer so as to enable the wire within the polymer and to fill any gaps in the structure of the wire fabric, thereby providing a monolithic coated wire fabric.
The coated wire fabric may further comprise a lacquer layer.
The hot melt thermoplastic polymer may be selected from the list of urethanes, vinyl chlorides, olefins, PVDF or the like.
The wire fabric may be stab resistant.
The wire fabric may comprise woven, knitted or twisted wires. The wires may be woven as warp and weft threads or warp or weft threads alone.
The wire fabric may comprise the fabric disclosed in EP 0 879 001, i. e. a plurality of steel cords, each of said steel cords comprising a longitudinal axis and two or more steel filaments, each of said steel
filaments forming a twisting angle with the longitudinal axis of said steel cord, said steel cords having two or more of such twisting angles which are substantially different from each other.
According to a third aspect of the invention there is provided the use of a coated wire fabric as hereinbefore defined as a curtain or shutter. The coated wire fabric may comprise a curtain acting as a closure for a vehicle.
According to a fourth aspect of the invention there is provided the use of a coated wire fabric as hereinbefore defined in a marine application.
The coated wire fabric may form part of, or comprise, a raft, oil boom, cargo net, reinforcing barrier or hovercraft skirt.
According to a fifth aspect of the invention there is provided an architectural use of a coated wire fabric as hereinbefore defined. The coated wire fabric may form part of, or comprise, walling, roofing, a tent, a marquee, or other protective layers.
According to a sixth aspect of the invention there is provided a flexible storage tank comprising a coated wire fabric as hereinbefore defined. The storage tank may be a fuel tank or water storage tank.
According to a seventh aspect of the invention there is provided a cargo hold comprising a coated wire fabric as hereinbefore defined.
Coated wire fabrics and methods for the production thereof will now be described with reference to the accompanying drawings, in which:- Figure 1 is a schematic diagram of the coating apparatus ; and
Figure 2 is a cross sectional diagram of coated wire fabric.
The wire fabrics which are coated by the method of the invention can comprise woven, knitted or twisted wires, such as steel cords. The wires can be twisted together to produce warp and weft threads. An example of a suitable wire fabric is described in European Patent EP 0 879 001, the contents of which are herein incorporated by reference, although the invention is not limited in this regard. The wire fabric can comprise, for example, galvanise filaments twisted together to produce warp and weft threads. The fabric can be produced by weaving or knitting the wire threads together.
A woven substrate 10 based on synthetic or natural yarns or a non- woven base is pre-treated on a stenter with a high concentration of a suitable water and oil repellent finish. This acts as a carrier fabric for the wire fabric through the coating process.
The coating of a hot melt polymer, which can be based on thermoplastic polymers such as urethanes, vinyl chlorides, olefins, PVDF or other suitable polymers is dried and blended, if appropriate, with a quantity of pigment master batch, for an appropriate period of time, typically two hours. The coating is one that allows itself to be melted and cast into a film which solidifies on cooling. The process is repeatable many times without loss of properties or characteristics.
As shown in Figure 1 a coating is extruded into a gap created by hot
calendar rollers 14,16 at temperatures between 120 and 200°C to form a film between 150 g/m2 to 300 g/m2. This film is laminated onto a woven -carrier fabric. The process is repeated to the required thickness. Two calendar rollers 14,16 allow the holt melt coating to be formed into a film of predetermined thickness. The film is then laminated onto a suitable substrate that removes the film from the calendar roller. This is a continuous coating and laminating process. It is possible to employ more than two calendar rollers : such variations are well known to those skilled in the coating art. The extrusion of the holt melt polymer is performed using a heated barrel 12 containing a tightly fitting heated screw (not shown).
The heated screw generates heat and shear designed to melt the solid coating into a flowing malleable resin.
The coated fabric is then trimmed to an appropriate width using a hot knife to ensure proper edge sealing.
The coated fabric is broken down into lengths slightly greater than the supplied wire. The fabric is batched onto 3"internal diameter cores.
Using a modified frame the reel of wire fabric 18 is batched above a coated carrier roll 20. The carrier roll 20 is joined to the hot melt calendar machine leader fabric and then the wire fabric is taped to the coated carrier.
Independent breaking units ensure that both materials have adequate running tension and are free from creasing.
Both fabrics come together prior to laminating rolls 14,16 where a
weight of coating between 600 g/m2 to goo g/m2 is cast at a temperature between 120 and 200°C. The coating covers the wire threads and also strikes through the holes, melting the coating on the carrier fabric and thereby physically bonding to it.
The coated wire fabric and carrier fabric are wound together on a single frame 24.
The process is repeated whereby a further topcoat between 70 g/m2 to 200 g/m2 is applied to the surface of the bonded wire fabric.
The carrier fabric is then stripped from the coated wire fabric using a standard rewind table. The carrier is cleaned and re-batched ready for re- use at a later date.
The unsupported wire fabric is then given a final lacquer finish on the hot melt calendar coating machine at processing temperatures between 120 and 200°C. The side that was originally cast onto the woven carrier is the side that is given the final coating. The applied coating weight is between 70 g/m2 to 200 g/m2.
The edges of the coated wire fabric can be trimmed using conventional slitting technologies.
The final stage is to inspect and wrap the product prior to delivery.
The coated wire fabric product is strong, dimensionally stable and solid, weatherproof yet flexible, and can be stab resistant. Figure 2 shows a cross sectional view of coated wire fabric 30 according to the invention.
There are numerous applications for the coated wire fabrics of the invention, which can be used with advantage for these applications, owing to its advantageous properties. For example, there are potential military applications, such as shelters, rafts and flexible storage tanks. It should be noted that such items may also be used in a non-military context. Another broad area of application relates to security, e. g. the provision of roller shutters and cut and stab resistant curtains. Another broad area of application still relates to marine applications, such as in the manufacture of life rafts, oil booms, cargo nets, reinforcing barriers and hovercraft skirts.
Yet another broad area of application relates to various storage applications, such as the provision of flexible fuel or water tanks, cargo holds and trailer curtains.
Still another broad area of application relates to architectural uses of coated wire fabric, such as for walling, roofing, or other protective layers and in the fabrication of tents and marquees, wherein the coated wire fabric of the present invention can advantageously replace traditional materials such as tarpaulin. Further applications include use as advertising banners, and as reservoir/landfill covers.
In all of these application areas, there are advantages associated with the combination of toughness, durability and flexibility provided by fabrics of the present invention. In numerous applications, such as those described above relating to security, and in the provision of trailer curtains, it is a
further and considerable advantage that stab resistant fabrics of the present invention can be provided. For example, fabrics of the present invention -can be used as a curtain which acts as a closure for a vehicle such as a lorry, HGV or a trailer for such vehicles. It is a commonly encountered problem with such vehicles that thieves slash the curtain used to close such vehicles with knives or like cutting instruments and thereby gain entry to the contents of the vehicle. Another problem is that such curtains are slashed in order to allow illegal immigrants to hide themselves within the vehicle in order to gain illegal entry into a country into which the vehicle is transported. Thus, it is highly advantageous in such applications that fabrics of the present invention are flexible and stab resistant. Generally, the curtain comprises a sheet of coated wire fabric according to the invention, means to suspend the curtain from a portion of the container, and securing means, such as straps and buckles, which secures the container in place.
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