WO2016132139A1

WO2016132139A1 - Method for producing fabric

Info

Publication number: WO2016132139A1
Application number: PCT/GB2016/050415
Authority: WO
Inventors: Elizabeth Fry; Kamlesh MISTRY
Original assignee: Heathcoat Fabrics Ltd
Priority date: 2015-02-19
Filing date: 2016-02-19
Publication date: 2016-08-25
Also published as: EP3259395A1; GB201502831D0

Abstract

A method for producing a fabric, the method comprising, providing a textile containing a chemically resistant yarn comprising poly(arylene sulphide), optionally scouring and optionally drying the textile, and plasma treating the textile in a plasma feed gas comprising oxygen. Fabrics produced according to the invention may be used in transmission belts, filters, pipe lining, conveyors and hose.

Description

Method for Producing Fabric

The present invention relates to methods for producing fabrics and fabrics produced by such methods. More particularly, the present invention relates to methods for producing fabrics having improved chemical resistance and improved adhesion to polymers.

Industrial fabrics often have to withstand aggressive chemical

environments for extended periods. Such aggressive chemical environments may be at high temperature, or may subject fabrics to high friction or high abrasion.

Industrial fabrics may be used in transmission belts, especially toothed transmission belts. Toothed transmission belts generally have a body of an elastomeric material, usually rubber, with a plurality of teeth covered by a coating fabric. The coating fabric is usually treated with an adhesive (for example, resorcinol formaldehyde latex, RFL) to increase adhesion between the rubber body and fabric. It is becoming commonplace for toothed belts to function in contact with, or even partially immersed in, oil which can be an aggressive chemical environment for industrial fabrics.

Other uses of industrial fabrics may be filtration systems where it is usually important that adhesion of particles to the filtration material is minimised, but adhesion to functional features e.g. specialised coatings may be important.

US-A-2006/0093820 discloses a functionalised plasma treated non-woven having excellent separation effect in the filtration of polymer compounds.

EP-A-451 425 discloses treatments of a polymeric reinforcement for the purpose of promoting adhesion to polymers using plasma treatment including CF4 which would have the effect of rendering the surface water-repelling, and to providing an adhering surface on reinforcement materials used as a reinforcing agents in rubber in a pneumatic tyre. US-A-2013/0035119 discloses functionalised plasma treated temperature resistant fabrics, having covalently bonded coatings on the fibres.

JP-B-2661137 discloses laminated board with a composite twisted woven textile having improved dielectric characteristics. Industrial fabrics may also be used in e.g. conveyor belts or hoses where aggressive chemicals may be present including concentrated acids or alkalis.

Industrial fabrics which are generally regarded as chemically resistant include aramids (aromatic polyamides). Unfortunately, aramids are generally only moderately resistant to acids or alkalis. In particular, m-aramids are generally only moderately resistant to concentrated alkalis and p-aramids only moderately resistant to concentrated acids.

For a number of uses of industrial fabrics (for example, transmission belts, hoses, conveyor belts) adhesion, especially to elastomeric polymers, is important. Unfortunately, materials that are chemically resistant usually have poor adhesion. It is an aim of the present invention to address the problems discussed above.

The present invention accordingly provides, in a first aspect, a method for producing a fabric, the method comprising, a) providing a textile containing a chemically resistant yarn comprising poly(arylene sulphide), preferably poly(phenylene sulphide), c) optionally scouring and optionally drying the textile, and d) plasma treating the textile in a plasma feed gas comprising oxygen.

Such a method of using plasma treatment, especially wherein the plasma feed gas comprises oxygen, is beneficial because it surprisingly provides enhanced adhesion of polymeric or other materials to the surface of the fabric, whilst retaining the beneficial chemical resistance of a poly(arylene sulphide) material. Previously, it has been difficult to achieve both chemical resistance (especially in acid or alkaline environments or other aggressive environments) and acceptable adhesion for use of a fabric in various applications. Even more surprisingly, the beneficial properties of plasma treatment are retained even up to at least 5 days after plasma treatment even when the treated textile is stored in air (i.e. when no special storage conditions are used other that storage in generally clean and dry conditions). In order to provide more enhanced adhesion, preferably, the plasma feed gas does not comprise polymeric precursor molecules. More preferably the plasma feed gas does not comprise fluorinated alkanes, and even more preferably does not contain fluorinated methane (CF_n, wherein n is 1, 2, 3, or 4). Most preferably, the plasma feed gas does not contain CF4. Preferably, the textile is an interlaced textile. The interlaced textile may be a knitted textile. Preferably, however, the interlaced textile is a woven textile. A preferred weave pattern is a twill or a matt, for example a 2x2 twill, a 2x2 matt, a 3 x3 twill or a 2x4 reversing twill. Usually, the woven textile will have a multiple pick weave pattern, preferably a double pick weave pattern. One of the advantages of the present invention is that poly(arylene sulphide) materials are usually thermoplastic. This is advantageous because it enables the yarn comprising a poly(arylene sulphide) to be bulked-up by a texturizing process. Thus, preferably the chemically resistant yarn comprises a texturised yarn. A convenient and advantageous process is false twist texturizing of yarn. Thus, preferably, the texturised yarn comprises false twist texturised yarn.

Texturised yarn is advantageous because it imparts a bulkier appearance, and creates a greater space between the yarn filaments. Furthermore, texturising imparts a stretch characteristic to the yarn which means the textile can be used in applications which require conformation to complex shapes, or where an element of flexibility is required in the final product. In addition after texturisation, the textured nature of the yarn allows better penetration of subsequent finishes (e.g. primers or polymer materials) into the fabric, which may help to increase mechanical adhesion.

Textiles as used in the present invention may contain only yarn comprising poly(arylene sulphide). However, often for reasons of cost or to modify the tensile or other properties of the textile, the textile may contain a second yarn, a third yarn and/or a further yarn.

The second yarn may comprise a polyamide, for example polyamide 66. This is advantageous because such a yarn is reasonably strong, cost effective and thermoplastic enabling the second yarn to be texturised if desired.

Usually, when the textile is a woven textile, the second yarn will form at least some of the warp threads of the textile. Usually, the chemically resistant yarn will form at least some of the weft threads of the textile.

The chemically resistant yarn may form all of the weft threads of the woven textile. Additionally or alternatively, the chemically resistant yarn may form all of the warp threads of woven textile.

In preferred embodiment, the chemically resistant yarn (preferably PPS) forms all of the weft threads of the woven textile and the second yarn (preferably polyamide) forms all of the warp threads of the woven textile. It is advantageous to clean and/or scour the textile after it is formed and before plasma treatment. This is advantageous because it reduces or removes any contaminants (e.g. processing aids from previous production stages such as lubricating oils or waxes) that may be on the surface of the textile or fibres.

It is advantageous if, after cleaning, the textile is dried. Advantageously, the textile may be agitated during drying to impart bulk into the yarn. This may also develop the stretch characteristics engineered during the optional texturing process. Alternatively, drying may involve a setting process to achieve dimensional stability and create a more rigid fabric structure.

It is preferred if the plasma feed gas does not comprise intentionally added monomers because such monomers may adversely functionalise the surface of the textile or the textile fibres.

The plasma treatment may be conducted at around atmospheric pressure. Usually, however, plasma treatment comprises plasma treating the textile in an at least partially evacuated chamber. The at least partially evacuated chamber may be at a pressure of 0.5 atm or lower.

It is convenient and efficient if the plasma treatment comprises plasma treating the textile using a roll to roll sample transport system. It is generally difficult to adhere e.g. polymers to chemically resistant yarns. Such yarns often have relatively low surface energy. Surprisingly the present inventors have discovered that increasing the surface energy of chemically resistant yarns, for example PPS, can be achieved using plasma treatment without significantly compromising the chemical resistance within the main body of the textile.

Poly(arylene sulphide) may comprise a functionalised aryl group (with 1, 2 or 3 groups on the phenyl ring), of formula:

wherein R is/are one or more functional groups independently selected from halo, hydroxy or hydrocarbyl (preferably Ci to C₈, more preferably Ci to C4), and m is 0, 1, 2 or 3. Preferably, poly(arylene sulphide) comprises poly(phenylene sulphide).

The most preferred poly(arylene sulphide) comprises poly(p-phenylene sulphide) (PPS) a polymer of formula:

In preferred embodiments of the invention, the method may further comprise, e) contacting the plasma treated textile with a first liquid composition comprising at least a first precursor. This is advantageous because it may provide improved adhesion to e.g. elastomeric polymers for various uses. Such a first liquid composition may comprise a polymeric precursor (e.g. resorcinol formaldehyde resin precursor, a natural or synthetic elastomeric precursor).

However, preferably the first liquid composition comprises a primer. A preferred primer comprises an epoxy, and preferably further comprises a blocked isocyanate. This is advantageous because subsequent heat treatment causes the blocked isocyanate to unblock leading to reaction between the components of the primer and textile thus providing a more reactive surface with enhanced adhesive properties.

It is preferred if the textile is saturated with the primer in dispersion or solution.

In further embodiments of the invention, the method may further comprise, f) contacting the textile with a second liquid composition comprising at least a second precursor. Usually, the second liquid composition comprises a polymer latex. A preferred polymer latex comprises a resorcinol formaldehyde latex (RFL). An RFL is advantageous because it may improve the adhesion of the fabric to a wide range of materials including e.g. elastomers. Preferably the polymer latex comprises acrylonitrile butadiene rubber species ( BR) or precursors. More preferably the polymer latex comprises NBR and RFL.

Thus, in a second aspect, the present invention accordingly provides, a method for producing a fabric, the method comprising, a) providing a plasma treated textile that has been treated using a plasma feed gas comprising oxygen, the textile comprising a chemically resistant yarn comprising poly(arylene sulphide), b) optionally contacting the plasma treated textile with a first liquid composition comprising at least a first precursor, and c) optionally, contacting the textile with a second liquid composition comprising at least a second precursor.

This is greatly advantageous because fabrics according to the second aspect of the invention (especially with the optional step(s)) can have adhesion (as shown by adhesion testing) significantly greater than without the steps of the invention.

In a third aspect, the present invention provides a fabric comprising a plasma treated textile that has been treated using a plasma feed gas comprising oxygen, the textile comprising a chemically resistant yarn of poly(arylene sulphide).

Preferably, the fabric further comprises a coating on at least some of the surface of the fabric, wherein the coating comprises an epoxy composition.

Preferably, the fabric further comprises an elastomeric polymer adhered to at least part of the surface of the fabric.

The fabric will usually be an interlaced fabric, preferably a woven fabric.

Fabrics produced according to the first or second aspects of the invention, or fabrics according to the third aspect of the invention find use in many industrial applications. One suitable application is to incorporate such fabrics in transmission belts, in particular, toothed transmission belts. Thus, an aspect of the invention provides a transmission belt, preferably a toothed belt, comprising a woven fabric produced according to the first or second aspect of the invention or according to the third aspect of the invention adhered to its working surface. Such a

transmission belt is particularly hard wearing in oil-containing, or other chemically aggressive, environments.

Another suitable application is to incorporate such fabrics in conveyor systems, in particular conveyor belts or dryer belts Thus, an aspect of the invention provides a conveyor belt or a dryer belt comprising a woven fabric produced according to the first or second aspect of the invention or according to the third aspect of the invention.

A further suitable application is to incorporate such fabrics in hoses. Thus, an aspect of the invention provides a hose comprising a woven fabric produced according to the first or second aspect of the invention or according to the third aspect of the invention.

A still further suitable application is to incorporate such fabrics in oil pipe linings or gas pipe linings. Thus, an aspect of the invention provides an oil pipe lining or a gas pipe lining comprising a woven fabric produced according to the first or second aspect of the invention or according to the third aspect of the invention.

Yet another suitable application is to incorporate such fabrics in filtration systems. Thus, an aspect of the invention provides a filtration system (e.g. a filter) comprising a woven fabric produced according to the first or second aspect of the invention or according to the third aspect of the invention.

Many of the optional and preferred features of the third aspect of the invention correspond to those of the first or second aspects with appropriate modification. The above and other characteristics, features and advantages of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the invention. This description is given for the sake of example only, without limiting the scope of the invention. It is to be noted that the term "comprising", used in the claims, should not be interpreted as being restricted to the means listed thereafter; it does not exclude other elements or steps. It is thus to be interpreted as specifying the presence of the stated features, integers, steps or components as referred to, but does not preclude the presence or addition of one or more other features, integers, steps or components, or groups thereof. Thus, the scope of the expression "a device comprising A and B" should not be limited to devices consisting only of components A and B.

Reference throughout this specification to "an embodiment" or "an aspect" means that a particular feature, structure or characteristic described in connection with the embodiment or aspect is included in at least one embodiment or aspect of the present invention. Thus, appearances of the phrases "in one embodiment", "in an embodiment", or "in an aspect" in various places throughout this specification are not necessarily all referring to the same embodiment or aspect, but may refer to different embodiments or aspects. Furthermore, the particular features, structures or characteristics of any embodiment or aspect of the invention may be combined in any suitable manner, as would be apparent to one of ordinary skill in the art from this disclosure, in one or more embodiments or aspects.

Similarly, it should be appreciated that in the description various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various inventive aspects. This method of disclosure, however, is not to be interpreted as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Moreover, the description of any individual drawing or aspect should not necessarily be considered to be an embodiment of the invention. Rather, as the following claims reflect, inventive aspects lie in fewer than all features of a single foregoing disclosed embodiment. Thus, the claims following the detailed description are hereby expressly incorporated into this detailed description, with each claim standing on its own as a separate embodiment of this invention.

Furthermore, while some embodiments described herein include some features included in other embodiments, combinations of features of different embodiments are meant to be within the scope of the invention, and form yet further embodiments, as will be understood by those skilled in the art. For example, in the following claims, any of the claimed embodiments can be used in any combination.

In the description provided herein, numerous specific details are set forth. However, it is understood that embodiments of the invention may be practised without these specific details. In other instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of this description.

In the discussion of the invention, unless stated to the contrary, the disclosure of alternative values for the upper or lower limit of the permitted range of a parameter, coupled with an indication that one of said values is more highly preferred than the other, is to be construed as an implied statement that each intermediate value of said parameter, lying between the more preferred and the less preferred of said alternatives, is itself preferred to said less preferred value and also to each value lying between said less preferred value and said intermediate value.

The present invention is illustrated by the accompanying drawings, in which:

Figure 1 illustrates schematically the weave pattern of a textile used in an embodiment of the present invention. The weave pattern is a 2x2 twill double pick.

Figure 2 illustrates schematically the weave pattern of another textile used in an embodiment of the present invention. The weave pattern is a 2x2 Matt construction.

Figure 3 illustrates schematically the weave pattern of a further textile used in an embodiment of the present invention. The weave pattern is a 2x4 broken/reversing twill.

Figure 1 shows the weave pattern of textile used in the Examples 1 and 2 and the Comparative Examples, below.

Figure 2 shows a weave pattern for a textile/fabric that provides reduced skew and aids alignment of the weft yarn with the working direction of a transmission belt, when the fabric is used in such belts.

Figure 3 shows the weave pattern of a textile/fabric that provides a smoother fabric surface which is advantageous because it reduces tracking effects in transmission belts, when the fabric is used in such belts. The invention is further illustrated by the following Examples.

Examples 1 and 2 and Comparative Examples A and B.

In the Examples, a fabric according to an embodiment of the invention was produced.

The warp yarn was PA66 235dtex comprising 34 filaments. The weft yarn was texturised PPS 220dtex comprising 50 filaments. The yarns were woven in a 2x2 twill double pick according to the weave pattern of Figure 1.

PPS was false twist texturised before weaving. After weaving, the textile was cleaned/scoured and dried.

Examples 1 and 2 were plasma treated. Comparative Examples A and B were not plasma treated.

Plasma treatment used a high frequency plasma in an evacuated plasma chamber using a roll to roll sample transport system. The plasma feed gas comprised oxygen.

The samples were subsequently treated (as indicated below) five days after plasma treatment. During that time, the samples were covered, and stored in air.

The Examples and Comparative Examples were then treated by dipping in a primer composition of epoxy and blocked isocyanate and/or a resorcinol formaldehyde latex as indicated in Table 1. The samples were subsequently tested for adhesion, the results are indicated in Table 1.

Example or Average Comparative Plasma Dipped in Dipped in Adhesion treatment Primer RFL (N / 25 mm)

Comparative

Example A No No Yes 1 19.9

Example 1 Yes No Yes 172.9

Comparative

Example B No Yes Yes 161.2

263.0

Example 2 Yes Yes Yes (Rubber Tear)

Table 1

Production lots of fabric according to Example 2 produced adhesion results of 188 N / 25 mm, 187 N / 25 mm and 184 N / 25 mm.

Adhesion testing was conducted by testing in the warp direction of the fabric. The adhesion test was carried out by pressing the textile against a compatible rubber (hydrogenated acrylonitrile butadiene rubber (HNBR)) at a temperature of 170°C for 30 minutes. The textile (a 25 mm wide specimen) was separated from the rubber compound using a constant rate of extension (50 mm / min peel, Instron) and the load required to separate the materials was measured.

Example 3 A fabric was produced using a 3 ^χ3 twill double pick weave pattern using the yarns of Examples 1 and 2, as discussed above. All other steps of the production of the fabric were as for Examples 1 and 2.

After plasma treatment as discussed in Examples 1 and 2, dipping in primer and dipping in RFL, average adhesion was 187 N / 25 mm.

Claims

Claims.

1. A method for producing a fabric, the method comprising,

a) providing a textile containing a chemically resistant yarn comprising poly(arylene sulphide),

c) optionally scouring and optionally drying the textile, and d) plasma treating the textile in a plasma feed gas comprising oxygen.

2. A method as claimed in claim 1, wherein the textile is an interlaced textile.

3. A method as claimed in claim 2, wherein the interlaced textile is a woven textile.

4. A method as claimed in claim 3, wherein the woven textile has a twill or matt weave pattern, preferably selected from a 2x2 twill, a 2x2 matt, a 3 x3 twill and a 2x4 reversing twill.

5. A method as claimed in either claim 3 or claim 4, wherein the woven textile has a multiple pick weave pattern, preferably a double pick weave pattern.

6. A method as claimed in any one of the preceding claims, wherein the chemically resistant yarn comprises a texturised yarn.

7. A method as claimed in claim 6, wherein the texturised yarn comprises false twist texturised yarn.

8. A method as claimed in any one of the preceding claims, wherein the textile contains at least a second yarn.

9. A method as claimed in any one of the preceding claims, wherein the second yarn comprises a polyamide.

10. A method as claimed in any one of the preceding claims, wherein plasma treating comprises plasma treating the textile in an at least partially evacuated chamber.

11. A method as claimed in any one of the preceding claims, wherein plasma treating comprises plasma treating the textile using a roll to roll textile transport system.

12. A method as claimed in any one of the preceding claims, wherein poly(arylene sulphide) comprises poly(phenylene sulphide), preferably poly(p- phenylene sulphide).

13. A method as claimed in any one of the preceding claims, further comprising, e) contacting the plasma treated textile with a first liquid composition comprising at least a first precursor.

14. A method as claimed in claim 13, wherein the first liquid composition comprises a primer.

15. A method as claimed in claim 14, wherein the primer comprises an epoxy, and preferably comprises a blocked isocyanate.

16. A method as claimed in claim 15, further comprising, f) contacting the textile with a second liquid composition comprising at least a second precursor.

17. A method as claimed in claim 16, wherein the second liquid composition comprises a polymer latex, preferably comprising an elastomeric polymer.

18. A method as claimed in claim 17, wherein the polymer latex comprises a resorcinol formaldehyde latex.

19. A method for producing a fabric, the method comprising, a) providing a plasma treated textile that has been plasma treated using a plasma feed gas comprising oxygen, the textile comprising a

chemically resistant yarn comprising poly(arylene sulphide),

b) contacting the plasma treated textile with a first liquid composition comprising at least a first precursor, and c) optionally, contacting the textile with a second liquid composition comprising at least a second precursor.

20. A fabric comprising a plasma treated textile that has been treated using a plasma feed gas comprising oxygen, the textile comprising a chemically resistant yarn of poly(arylene sulphide).

21. A fabric as claimed in claim 20, further comprising a coating on at least a portion of the surface of the fabric, wherein the coating comprises an epoxy composition.

22. A fabric as claimed in either claim 20 or claim 21, further comprising an elastomeric polymer adhered to at least part of the surface of the fabric.

23. A fabric as claimed in any one of claims 20 to 22, wherein the fabric is an interlaced fabric, preferably a woven fabric.

24. A fabric as claimed in any one of claims 20 to 23, wherein poly(arylene sulphide) comprises poly(phenylene sulphide), preferably poly(p-phenylene sulphide).

25. A transmission belt, preferably a toothed belt, comprising a woven fabric produced as claimed in any one of claims 1 to 19 or as claimed in any one of claims 20 to 24, adhered to its working surface.

26. A conveyor belt or a dryer belt comprising a woven fabric produced as claimed in any one of claims 1 to 19 or as claimed in any one of claims 20 to 24.

27. A hose comprising a woven fabric produced as claimed in any one of claims 1 to 19 or as claimed in any one of claims 20 to 24.

28. A pipe lining comprising a woven fabric produced as claimed in any one of claims 1 to 19 or as claimed in any one of claims 20 to 24.

29. A filter comprising a woven fabric produced as claimed in any one of claims 1 to 19 or as claimed in any one of claims 20 to 24.