METHOD AND APPARATUS FOR IMPREGNATING REINFORCEMENT MATERIAL

Abstract

There is provided a process for preparing a prepreg (31) comprising reinforcement fibre (13) impregnated with a thermosetting resin matrix (20), said process comprising: a) providing a layer (24) of reinforcement fibre (13); b) applying a layer (24) of a first thermosetting resin matrix (20) to the first surface (15) of the layer (24) of reinforcement fibre (13) and bringing the first surface (15) of the layer (24) of reinforcement fibre (13) into contact with the support surface (5) of a first continuous belt (3), so that the layer (24) of first thermosetting resin matrix (20) is positioned between, and in contact with, the first surface (15) of the layer (24) of reinforcement fibre (13) and the support surface (5) of the first continuous belt (3); c) heating the layer (24) of first thermosetting resin matrix (20) applied to the first surface (15) of the layer (24) of reinforcement fibre (13) in contact with the support surface (5) of the first continuous belt (3); d) bringing the second surface (17) of the layer (24) of reinforcement fibre (13) into contact with the support surface 9) of a second continuous belt (7); e) heating the layer (24) of first thermosetting resin matrix (20) and the layer (24) of reinforcement fibre (13) between the support surfaces of the first and second continuous belts (3, 7) so that the first thermosetting resin matrix (20) impregnates the layer (24) of reinforcement fibre (13); f) cooling the layer (24) of reinforcement fibre (13) impregnated with the first thermosetting resin matrix (20) between the support surfaces of the first and second continuous belts (3, 7); and g) removing the layer (24) of reinforcement fibre (13) impregnated with the first thermosetting resin matrix (20) from the support surfaces of the first and second continuous belts (3, 7).

Claims

1. A process for preparing a prepreg comprising reinforcement fibre impregnated with a thermosetting resin matrix, said process comprising: a) providing a layer of reinforcement fibre; b) applying a layer of a first thermosetting resin matrix to the first surface of the layer of reinforcement fibre and bringing the first surface of the layer of reinforcement fibre into contact with the support surface of a first continuous belt, so that the layer of first thermosetting resin matrix is positioned between, and in contact with, the first surface of the layer of reinforcement fibre and the support surface of the first continuous belt; c) heating the layer of first thermosetting resin matrix applied to the first surface of the layer of reinforcement fibre in contact with the support surface of the first continuous belt; d) bringing the second surface of the layer of reinforcement fibre into contact with the support surface of a second continuous belt; e) heating the layer of first thermosetting resin matrix and the layer of reinforcement fibre between the support surfaces of the first and second continuous belts so that the first thermosetting resin matrix impregnates the layer of reinforcement fibre; f) cooling the layer of reinforcement fibre impregnated with the first thermosetting resin matrix between the support surfaces of the first and second continuous belts; and g) removing the layer of reinforcement fibre impregnated with the first thermosetting resin matrix from the support surfaces of the first and second continuous belts.

2. The process according to claim 1, wherein the layer of first thermosetting resin matrix is applied directly to the first surface of the layer of reinforcement fibre, as a liquid or semisolid film.

3. The process according to claim 2, wherein the layer of first thermosetting resin matrix is applied to the first surface of the layer of reinforcement fibre without the use of a backing layer.

4. The process according to claim 3, wherein the layer of first thermosetting resin matrix applied to the first surface of the layer of reinforcement fibre is heated in contact with the support surface of the first continuous belt to a temperature of from 45 to 100 C.

5. The process according to claim 4, wherein the layer of first thermosetting resin matrix applied to the first surface of the layer of reinforcement fibre is heated in contact with the support surface of the first continuous belt over a distance of from 2 to 20 m.

6. The process according to claim 4, wherein the layer of first thermosetting resin matrix applied to the first surface of the layer of reinforcement fibre is heated in contact with the support surface of the first continuous belt by heating the support surface of the first continuous belt by passing the support surface of the first continuous belt over a curved heated surface.

7. The process according to claim 6, wherein the support surface of the first continuous belt and the support surface of the second continuous belt is continuous, wherein the support surface of the first continuous belt and wherein the support surface of the first continuous belt and the support surface of the second continuous belt is formed from PTFE, silicone, silane or polished metal.

8. The process according to claim 6, further comprising applying a layer of a second thermosetting resin matrix to the second surface of the layer of reinforcement fibre before the second surface of the layer of reinforcement fibre is bought into contact with the support surface of the second continuous belt.

9. The process according to claim 8, wherein the layer of second thermosetting resin matrix is applied to the second surface of the layer of reinforcement fibre after the heating of the layer of first thermosetting resin matrix applied to the first surface of the layer of reinforcement fibre in contact with the support surface of the first continuous belt.

10. The process according to claim 8, wherein the layer of second thermosetting resin matrix is applied to the second surface of the layer of reinforcement fibre before the heating of the layer of first thermosetting resin matrix and the first surface of the layer of reinforcement fibre in contact with the support surface of the first continuous belt; and wherein the layer of second thermosetting resin matrix is applied to the second surface of the layer of reinforcement fibre at essentially the same time as the layer of first thermosetting resin matrix is applied to the first surface of the layer of reinforcement fibre.

11. The process according to claim 8, wherein the ratio of the weight of the layer of first thermosetting resin matrix to the weight of the layer of second thermosetting resin matrix is from 1:1 to 10:1.

12. The process according to claim 11, wherein the first thermosetting resin matrix and the second thermosetting resin matrix are the same material.

13. The process according to claim 11, wherein the heating in step e) is carried out at a higher temperature than the temperature in step c), preferably wherein the heating in step e) is carried out at a temperature of from 60 to 200 C.

14. The process according to claim 11, wherein the heating in step e) is carried out over a distance of from 1 to 10 m.

15. The process according to claim 11, wherein in step f) the layer of reinforcement fibre impregnated with the first thermosetting resin matrix is cooled between the support surfaces of the first and second continuous belts to a temperature of from 0 to 20 C.

16. The process according to claim 11, wherein the cooling in step f) is carried out over a distance of from 1 to 10 m.

17. (canceled)

18. (canceled)

19. (canceled)

20. (canceled)

21. The process according to claim 11, wherein the width of the layer of the first thermosetting resin matrix applied to the first surface of the layer of reinforcement fibre is less than the width of the layer of reinforcement fibre, and wherein the layer of the first thermosetting resin matrix is applied centrally to the first surface of the layer of reinforcement fibre so that uncoated regions of similar width are present at both edges of the first surface of the layer of reinforcement fibre following application of the layer of first thermosetting resin matrix.

22. (canceled)

23. An apparatus for preparing a prepreg comprising reinforcement fibre impregnated with a thermosetting resin matrix, said apparatus comprising: a) means for applying a layer of a first thermosetting resin matrix to the first surface of a layer of reinforcement fibre; b) a first continuous belt comprising a support surface for receiving the first surface of the layer of reinforcement fibre, so that the layer of first thermosetting resin matrix is positioned between, and in contact with, the first surface of the layer of reinforcement fibre and the support surface of the first continuous belt; c) means for heating the layer of first thermosetting resin matrix applied to the first surface of the layer of reinforcement fibre in contact with the support surface of the first continuous belt; d) a second continuous belt comprising a support surface, and means for bringing the second surface of the layer of reinforcement fibre into contact with the support surface of the second continuous belt; e) means for heating the layer of first thermosetting resin matrix and the layer of reinforcement fibre between the support surfaces of the first and second continuous belts so that the first thermosetting resin matrix impregnates the layer of reinforcement fibre; f) means for cooling the layer of reinforcement fibre impregnated with the first thermosetting resin matrix between the support surfaces of the first and second continuous belts; and g) means for removing the layer of reinforcement fibre impregnated with the first thermosetting resin matrix from the support surfaces of the first and second continuous belts.

24. (canceled)

25. (canceled)

26. (canceled)

27. The apparatus according to claim 23, wherein the means for heating the layer of first thermosetting resin matrix applied to the first surface of the layer of reinforcement fibre in contact with the support surface of the first continuous belt comprises a heated curved surface.

28. (canceled)

29. The apparatus according to claim 23, wherein the means for heating the layer of first thermosetting resin matrix and the layer of reinforcement fibre between the support surfaces of the first and second continuous belts so that the first thermosetting resin matrix impregnates the layer of reinforcement fibre comprises a dual belt press.

30. (canceled)

Description

[0066] The invention will now be explained by way of example only, and with reference to the following Figures, in which:

[0067] FIG. 1 is a diagrammatic example of a nip process of impregnation of the prior art;

[0068] FIG. 2 is a diagram of a first embodiment of the present invention; and

[0069] FIG. 3 is a diagram of a second embodiment of the present invention.

[0070] FIG. 1 has been discussed in the introductory part of the description.

[0071] FIG. 2 shows an apparatus 1 for preparing a prepreg comprising reinforcement fibre impregnated with a thermosetting resin matrix.

[0072] The apparatus 1 comprises a first continuous belt 3 having a support surface 5, and a second continuous belt 7 having a support surface 9. The continuous belts 3,7 are each supported by pairs of rollers 11, with the support surfaces 5,9 not engaging with the rollers. Each continuous belt 3,7 is formed from a continuous layer of PTFE. The apparatus 1 further comprises a set of rollers 12 for guiding a layer of reinforcement fibre 13 having a first surface 15 and a second surface 17 unwound from a master roll 18 so that the first surface 15 contacts the support surface 5 of the first continuous belt 3.

[0073] The apparatus 1 additionally comprises a first slot die 19 for depositing a layer or film 20 of liquid or semisolid thermosetting resin matrix onto the first surface 15 of the layer of reinforcement fibre 13. The slot die 19 is arranged to deposit the layer of resin 20 onto the first surface 15 of the layer of reinforcement resin 13 before the first surface 15 contacts the support surface 5 of the first continuous belt 3, so that the layer or resin 20 is positioned between the first surface 15 of the layer of reinforcement fibre 13 and the support surface 5 of the first continuous belt 3 following contact. The apparatus 1 also comprises a heat table 23 arranged to heat the layer of thermosetting resin matrix 20 applied to the first surface 15 of the layer of reinforcement fibre 13 as the first continuous belt 3 passes over the heat table 23. The length of the heat table may be from 4 to 15 m, such as 8 m, and the heat table 23 is adapted to heat the film of thermosetting resin matrix 20 to a temperature of from 40 to 120 C., optionally in 3 separate stages of increasing temperature.

[0074] The surface of the heat table 23 in contact with the first continuous belt 3 may be curved upwards, for example with a 30 metre radius degree of curvature, to increase the pressure between the support surface 5 of the first continuous belt 3 and the first surface 15 of the layer of reinforcement fibre 13 and to thereby improve impregnation of the layer of thermosetting resin matrix 20 into the layer of reinforcement fibre 13.

[0075] The apparatus 1 additionally comprises a second slot die 21 for depositing a second layer 24 of liquid or semisolid thermosetting resin matrix onto the second surface 17 of the layer of reinforcement fibre 13. The second slot die 21 is arranged to deposit the second layer of resin 24 onto the second surface 17 of the layer of reinforcement resin 13 before the second surface 17 contacts the support surface 9 of the second continuous belt 7, but after the heating of the first layer of thermosetting resin matrix 20 applied to the first surface 15 of the layer of reinforcement fibre 13 in contact with the support surface 5 of the first continuous belt 3.

[0076] In an alternative embodiment, the second slot die 21 is arranged to deposit the second layer of resin 24 onto the second surface 17 of the layer of reinforcement resin 13 before the heating of the first layer of thermosetting resin matrix 20 applied to the first surface 15 of the layer of reinforcement fibre 13 in contact with the support surface 5 of the first continuous belt 3; for example, the second slot die 21 may be arranged to deposit the second layer of resin 24 onto the second surface 17 of the layer of reinforcement resin 13 at essentially the same time that the first slot die 19 deposits the layer of resin 20 onto the first surface 15 of the layer of reinforcement resin 13.

[0077] The apparatus 1 additionally comprises a belt press component 25. The belt press component 25 may be arranged to provide a degree of compression between the support surfaces 5, 9 of the first and second continuous belts 3,7; and preferably the degree of compression is relatively low, such as 0.3 bar. For example, the gap between the support surfaces 5,9 of the first and second continuous belts 3,7 is just less than the thickness of the layer of reinforcement fibre 13 and the first and second films of thermosetting resin matrix 20,24, so that the pressure applied to the layers of resin 20,24 is sufficient to promote good heat transfer between the layers 20,24 and the support surfaces 5,9 without causing any of the resin to be squeezed out of the belt press 25.

[0078] The belt press component 25 comprises a first, heating, zone 27 and a second, cooling, zone 29. The heating zone 27 is arranged to heat the first and second layers of thermosetting resin matrix 20,24 and the layer of reinforcement fibre 13 to a greater temperature than the temperature produced by the heat table 23, and preferably to a temperature of from 60 to 200 C. The heating zone 27 may have any suitable length to promote sufficient impregnation of the layers of thermosetting resin 20,24 into the layer of reinforcement fibre 13 to produce a thermosetting resin impregnated layer of reinforcement fibre or prepreg 31, but preferably the length is from 1 to 10 m, such as 4 or 5 m. The cooling zone 29 is arranged to cool the prepreg 31 formed in the heating zone 27 sufficiently to allow any of the thermosetting resin matrix of the layers 20,24 remaining on the surface of the prepreg 31 to be removed from the support surfaces 5,9 of the first and second continuous belts 3,7, and preferably to a temperature of from 0 to 20 C., such as 4 or 5 C. The cooling zone 29 may be any length sufficient to effectively cool the prepreg 31, but is preferably from 1 to 10 m, such as 4 or 5 m. The belt press 25 may also be configured to provide a degree of pressure between the support surfaces 5,9 of the continuous belts 3,7 in the cooling zone 29, and preferably the degree of pressure is sufficient to promote good contact between the support surfaces 5,9 of the continuous belts 3,7 with the prepreg 31 to promote cooling of the prepreg 31 but not to prevent release of any of the resin forming the layers of thermosetting resin matrix 20,24 from the support surfaces 5,9 of the continuous belts 3,7, such as a pressure of 0.3 bar.

[0079] The heating and cooling in the heating and cooling zones 27,29 may be provided in any convenient manner, such as by the use of fixed heating and cooling plates, or by modular heating and cooling components, such as small units connected to heating and cooling sources, so that the lengths of the respective heating and cooling zones 27,29 may be varied by varying the heating or cooling supplied to the individual units.

[0080] Optionally a region of increased pressure, or nip, 39 may be positioned between the heating zone 27 and the cooling zone 29 to promote the complete impregnation of the films of thermosetting resin 20,24 into the layer of reinforcement fibre 13. For example, the nip 39 may provide a pressure of 3 bar between the support surfaces 5,9 of the first and second continuous belts 3,7.

[0081] Following passage through the cooling zone 29, the prepreg 31 may be removed from the support surfaces 5,9 of the continuous belts 3,7; for example by winding the prepreg 31 onto a prepreg roll 33. Optionally, one or more backing sheets 35 may be applied to one or both surfaces of the prepreg 31 during the winding step.

[0082] The apparatus 1 may be operated at speeds of from 5 to 15 m/minute, such as from 7 to 12 m/minute.

[0083] FIG. 3 shows an apparatus 51 for preparing a prepreg comprising reinforcement fibre impregnated with a thermosetting resin matrix. In general, the apparatus 51 shown in FIG. 3 comprises components corresponding to the apparatus 1 shown in FIG. 2, and the same reference numerals are used in each Figure to indicate corresponding components in each apparatus. The principle differences in the apparatus 51 shown in FIG. 3 compared to the apparatus 1 shown in FIG. 2 is that the components of the apparatus 51 are all arranged generally at the same level, that the length of the first continuous belt 3 is greater than the length of the second continuous belt 7, and that the heat table 23 is positioned before the belt press 25 rather than above it.

EXAMPLE OF THE INVENTION

[0084] Prepreg was produced using a Flatbed laminating machine for textile industry by the method of the present invention. The machine had a preheating IR over the entry zone of the bottom belt, 2.3 m long heated zone with 18 spring-mounted heating elements, driven pressure roller and 1.15 m long cooled zone with 9 spring-mounted cooling elements. Trials were carried out with heated zone elements at temperatures between 100 and 120 C. and line speed between 4 and 7 m/min. Materials used in the trial were multiaxial E-glass fabrics, specifically Biax 600 and Triax 1200 gsm (widely used reinforcements in wind energy applications) with Hexcel M9.6 and M9.6LT epoxy formulated resins (also widely used matrices for Wind Energy prepregs) pre-filmed and applied to one side or both sides of the reinforcement prior to being processed into the laminator. Resin films areal weight was such to achieve a resin areal content between 35 and 50% (typical values in wind energy applications). Laminated products had the same quality as prepreg produced in conventional conversion machines, including: level of impregnation, resin distribution, tack, thermal and mechanical properties.