WOVEN FABRIC, VACUUM INDUCED RESIN INFUSION PROCESS AND FIBRE REINFORCED COMPOSITE

Abstract

The present invention relates to a woven fabric for the manufacture of fibre reinforced composites having an area weight from 100 to 200 g/m.sup.2 which comprises unidirectional reinforcing fibres, carbon fibres and flow passages forming elements arranged in warp and/or weft direction, and, optionally additives. The flow passages forming elements are arranged transverse to the reinforcing fibres and the carbon fibres forming flow passages at the side of the flow passages forming elements. Moreover, the present invention relates to a vacuum induced resin infusion process for forming a fibre reinforced composite from such woven fabric as well as the fibre reinforced composite.

Claims

1-15. (canceled)

16. A woven fabric for the manufacture of fibre reinforced composites having an area weight from 50 to 300 g/m.sup.2 comprising: a) 30 to 75% by weight unidirectional reinforcing fibres arranged in warp and/or weft direction, wherein the reinforcing fibres are selected from the group consisting of glass fibres, ceramic fibres, and combinations thereof, b) 20 to 50% by weight electrical conductive fibres arranged in warp and/or weft direction, c) 2 to 10% by weight flow passages forming elements arranged in warp and/or weft direction, wherein the flow passages forming elements are selected from the group consisting of monofilament yarn, glass yarn, carbon yarn, twisted yarn, covered yarn, and combinations thereof, and d) 0 to 5% by weight of at least one additive, the quantity proportions of components a) to d) add up to 100% by weight and wherein the flow passages forming elements are arranged substantially transverse to the reinforcing fibres and forming flow passages at the side of the flow passages forming elements.

17. The woven fabric of claim 16, wherein the woven fabric has an area weight between 70 and 250 g/m.sup.2.

18. The woven fabric of claim 16, wherein the flow passages forming elements are polymeric monofilaments.

19. The woven fabric of claim 18, wherein the polymeric monofilaments are selected from the group consisting of polyethylene terephthalate (PET), polypropylene, polybutylene terephthalate, polyamide (PA), and combinations thereof.

20. The woven fabric of claim 16, wherein the flow passages forming elements have a diameter of 50 to 350 m.

21. The woven fabric of claim 16, wherein the flow passages forming elements are positioned in a distance of 2 to 8 mm from each other.

22. The woven fabric of claim 16, wherein flow passages forming elements comprise bundles of at least 1 and at most 5 monofilaments.

23. The woven fabric of claim 16, wherein the reinforcing fibres have a diameter of 4 to 30 m.

24. The woven fabric of claim 23, wherein the reinforcing fibres are present as rovings.

25. The woven fabric of claim 16, wherein the electrical conductive fibres are selected from the group consisting of carbon fibres, recycled carbon fibres, metal wires, glass yarn wrapped around with metal wires, and metal coated synthetic yarns.

26. The woven fabric of claim 25, wherein that the electrical conductive fibres have a diameter of 4 to 30 m.

27. The woven fabric of claim 16, wherein the electrical conductive fibres are present as rovings.

28. The woven fabric of claim 16, wherein the additive is selected from the group consisting of at least one adhesion promoter to promote adhesion between the fabric and the resin, at least one bi-component yarn to provide a mechanical connection between transversal and longitudinal oriented fibers and combinations thereof.

29. The woven fabric of claim 16, wherein the woven fabric comprises a) 40 to 70% by weight of unidirectional reinforcing fibres arranged in warp and/or weft direction, b) 25 to 45% by weight of carbon fibres arranged in warp and/or weft direction and c) 3 to 8% by weight of flow passages forming elements arranged in warp and/or weft direction, the quantity proportions of components a) to d) adding up to 100% by weight.

30. The woven fabric of claim 16, wherein the woven fabric has a resistance in the range of <20 ohm in warp and/or weft direction measured on a sample of 12 cm12 cm.

31. A vacuum induced resin infusion process for forming a fibre reinforced composite comprising: a) providing a woven fabric according to claim 16, b) enclosing the woven fabric within a substantially air impervious casing having at least one means for applying a vacuum and at least one means for supplying a curable resin to the casing, c) applying a vacuum to the casing via the at least one means for applying the vacuum and the at least one means, d) introducing the curable resin via the at least one means for supplying a curable resin to the casing, and e) curing the resin to form the fibre reinforced composite.

32. The process of claim 28, wherein the at least one means for applying a vacuum and the at least one means for supplying a curable resin to the casing are located on opposite sides of the casing.

33. A fibre reinforced composite comprising the woven fabric of claim 16 and an infused and cured resin.

Description

[0039] FIG. 1 is a diagram showing the flow rate of the fabric of the comparative example 1

[0040] FIG. 2 is a diagram showing the flow rate of the fabric of the comparative example 2

[0041] FIG. 3 is a diagram showing the flow rate of the fabric of the example 1

[0042] FIG. 4 a top view of a fabric according to the present invention

[0043] FIG. 5 is a diagram showing the flow rate of the fabric of the example 2

COMPARATIVE EXAMPLE 1

[0044] The starting point was based on glass warp fabric which was first evaluated for transversal flow properties. At this stage there no carbon fibers were included.

[0045] The tested fabric (TEST2599) had the following construction: [0046] Weave pattern: Plain weave

[0047] Table 1 mentions the fibres used in comparative example 1.

TABLE-US-00001 TABLE 1 Nominal weight Orientation TEX [g/m.sup.2] Fiber Type Warp 200 94 E-Glass Weft 130 58 PET monofilament ( 0.35 mm)

[0048] The total weight of the fabric was 152 g/m.sup.2.

Infusion Setup

[0049] The infusion properties were tested with the following setup: [0050] Size of the preform 400600 mm (widthlength) [0051] 10 layers tested in 90-direction (weft direction=K22)

Resin System

[0052] The following resin and initiator were used: [0053] Resin: Ashland AME 6001 INF-135 (VE) [0054] Initiator: Norox MCP-75 1,5%

Results

[0055] FIG. 1 shows the flow rate of the fabric of the comparative example 1 as the dependence of the flow distance from the time. It was observed that the fabric of the comparative example 1 showed a far too high flow rate. It was concluded that the diameter of monofilament yarn used for flow enhancement has to be reduced.

COMPARATIVE EXAMPLE 2

[0056] Further infusions were made to optimize the flow properties and resin consumption. The use of 0.25 mm and 0.14 mm diameter monofilament was tested for flow properties. The next fabric was made with a lower filament diameter.

[0057] The second tested fabric (TEST2582) had the following construction: [0058] Weave pattern: Plain weave

[0059] Table 2 mentions the fibres used in comparative example 2.

TABLE-US-00002 TABLE 2 Nominal weight Orientation TEX [g/m.sup.2] Fiber Type Warp 200 94 E-Glass Weft 650 29 PET monofilament ( 0.25 mm)

[0060] The total weight of the fabric was 123 g/m.sup.2.

Infusion Setup

[0061] The infusion setup and other parameters are the same as in the first infusion setup (comparative example 1).

The Results

[0062] FIG. 2 shows the flow rate of the fabric of the preliminary test as the dependence of the flow distance from the time. It was observed that the fabric of comparative example 2 has is a lower flow rate than comparative example 1 which, however, was still too high. Hence, there was still a need to lower the flow rate.

EXAMPLE 1

[0063] In a further experiment carbon fibres were used in weft direction.

[0064] The carbon in weft direction was chosen to be 3K as it is of same tex as the warp direction. Using a higher tex would generate bumps on fabric. The weft monofilament area weight is only 5 g/m.sup.2 and should provide enough stability to the fabric and infusibility together with additional carbon.

[0065] The tested fabric (TEST3010) has the following construction: [0066] Weave pattern: Plain weave

[0067] Table 3 mentions the fibres used in example 1.

TABLE-US-00003 TABLE 3 Nominal weight Orientation TEX [g/m.sup.2] Fiber Type Warp 200 94 E-Glass 1.sup.st Weft 21 6 PET monofilament ( 0.14 mm) 2.sup.nd Weft 200 36 3K Carbon

[0068] The total weight of the fabric was 123 g/m.sup.2.

Infusion Setup

[0069] The infusion setup and other parameters are the same as for comparative examples 1 and 2.

The Results

[0070] The permeability of the fabric was improved compared to the comparative examples. 27% (36 g/m.sup.2) of the fabric weight refers to carbon fibers which was arranged in weft direction.

EXAMPLE 2

[0071] Further experiments were conducted with different fiber diameters of monofilament, the correct flow level (around 10 minutes for 50 cm width) was estimated to be reached with 140 m fiber diameter. In this case also the warp & weft-oriented carbon (3K) was added. The addition of carbon in warp direction does not seem to influence much on the flow characteristics of the fabric. The weft direction carbon adds a bit of thickness to the fabric and thereby enhances the flow properties.

[0072] The tested fabric (TEST2915) has the following construction: [0073] Weave pattern: Plain weave

[0074] Table 4 mentions the fibers used in example 2.

TABLE-US-00004 TABLE 4 Nominal weight Orientation TEX [g/m.sup.2] Fiber Type 1.sup.st Warp 200 75 E-Glass 2.sup.nd Warp 200 19 3K Carbon 1.sup.st Weft 21 6 PET monofilament ( 0.14 mm) 2.sup.nd Weft 200 36 3K Carbon

[0075] The total weight of the fabric was 136 g/m.sup.2.

Infusion Setup

[0076] The infusion properties are tested with the following setup: [0077] Size of the preform 400600 mm (widthlength) [0078] 10 layers tested in 90-direction (weft direction)

[0079] The fabric construction is shown in FIG. 4.

Resin System

[0080] The following resin and initiator were used: [0081] Resin: Ashland AME 6001 INF-135 (VE) [0082] Initiator: Norox MCP-75 1,5%

The Results

[0083] The infusion result was seen very interesting as it was fast enough and reached with rather low areal weight of fabric (136 g/m.sup.2) (s. FIG. 5).

[0084] The desired level of infusibility was reached and the conductivity of the material was found to be in target range. The conductivity can also be rather easily adapted by changing glass rovings in warp to carbon fibers or by changing monofilaments in weft to carbon fibres. The changes in warp had minimal effect on flow properties whereas the change in weft must be evaluated case by case.