VACUUM FORMING PROCESS

Abstract

The present invention relates to vacuum forming process for moulding a thermoset material and a start-up process for moulding a thermoset material. The present invention also relates to articles produced by the vacuum forming process.

Claims

1. A vacuum forming process for moulding a thermoset material, wherein the process comprises the following steps: (i) providing a mould for moulding a sheet of thermoset material, wherein the mould comprises an elastomeric material; (ii) placing a sheet of a phenolic thermoset material into contact with a surface of the mould; (iii) applying a vacuum such that the sheet of thermoset material is forced against the surface of the mould, and such that the sheet of thermoset material is at least partially cured.

2. A process according to claim 1, wherein the phenolic thermoset material comprises a thermosetting resin.

3. A process according to any preceding claim, wherein the phenolic thermoset material further comprises a polyester resin, a vinyl ester resin, an epoxy resin, or any combination thereof.

4. A processing according to claim 3, where in the thermoset material comprises: uncured phenolic resin; filler; a catalyst in an amount of less than 2 wt. % relative to the content of phenolic resin; and wherein the filler is present in a ratio of filler to uncured phenolic resin in an amount of 2.5:1 and greater, and further wherein the filler comprises a transition metal hydroxide and/or aluminium hydroxide in a ratio of metal hydroxide to uncured phenolic resin in an amount of 1:1.5 to 3:1.

5. A process according to claim 4, wherein the catalyst is present in an amount of less than 1 wt. % relative to the content of the uncured phenolic resin, preferably less than 0.5 wt. %, more preferably less than 0.2 wt. %, such as being substantially free of catalyst, and even free of catalyst.

6. A process according to claim 4 or claim 5, wherein the transition metal or aluminium hydroxides are of formula M(OH).sub.3, wherein M is a metal, for example one or more of scandium, vanadium, chromium, manganese, iron, cobalt and aluminium.

7. A process according to any preceding claim, wherein the thermoset material substantially covers the entire area of the mould.

8. A process according to any preceding claim, wherein the elastomeric material comprises a natural or synthetic rubber.

9. A process according to any preceding claim, wherein the elastomeric material comprises silicone.

10. A process according to any preceding claim, further comprising heating the sheet of thermoset material before the step of applying vacuum.

11. A process according to any preceding claim, further comprising heating the elastomeric mould material before the step of applying vacuum.

12. A process according to any preceding claim, wherein the sheet of thermoset material is heated to a temperature of at least 50 C.

13. A process according to claim 12, wherein the sheet of thermoset material is heated to a temperature of 100 to 200 C.

14. A process according to any preceding claim, wherein the step of applying a vacuum comprises applying a pressure of at least 0.5 bar but less than 1 bar.

15. A process according to any preceding claim, wherein the step of applying a vacuum comprises applying a pressure of from 0.7 bar to 0.9 bar.

16. A process according to any preceding claim, wherein the vacuum is applied by means of a vacuum pump.

17. A process according to any preceding claim, wherein the vacuum is created by use of a vacuum bag.

18. A process according to any preceding claim, wherein a layer of porous material is provided adjacent to the surface of the sheet of thermoset material that is not in contact with the mould.

19. A process according to claim 18, wherein the porous material comprises a foam.

20. A process according to claim 19, wherein the porous material is open-celled.

21. A process according to any one of claims 18 to 20, wherein the porous material is formed from phenolic or polyurethane resin.

22. A process according to claim 18, wherein the porous material is particulate in nature.

23. A process according to claim 22, wherein the layer of porous material is formed from sand.

24. A process according to any one of claims 18 to 23, wherein the layer of porous material substantially covers the sheet of thermoset material.

25. A process according to any one of claims 18 to 24, wherein at least a part of the layer of porous material adheres to the sheet of thermoset material.

26. A process according to any one of claims 18 to 25, wherein at least a part of the layer of the porous material remains adhered to the sheet of thermoset material after the step of applying vacuum.

27. A process according to any one of claims 18 to 26, wherein at least a part of the layer of porous material is profiled and/or shaped.

28. A process according to any preceding claim, wherein at least a part of the surface of the mould is coated with a dye, paint or ink, and wherein the step of applying vacuum causes the dye, paint or ink to be applied onto the surface of the sheet of thermoset material.

29. A process according to any preceding claim, wherein the mould has a specific shape such that the sheet of thermoset material is moulded into a specific shape on application of a vacuum.

30. A process according to claim 29, wherein the mould is shaped so as to have an undercut.

31. A start-up process for moulding a thermoset material, wherein the process comprises the following steps: (i) providing a pattern; (ii) providing an uncured elastomeric material and placing the uncured elastomeric material into contact with a surface of the pattern; (iii) allowing the uncured elastomeric material to cure so as to form a mould comprising elastomeric material; (iv) placing a sheet of thermoset material into contact with a surface of the mould; (v) applying a vacuum such that the sheet of thermoset material is forced against the surface of the mould, and such that the sheet of thermoset material is caused to cure.

32. A process according to claim 31, wherein the process is as defined in any one of claims 2 to 30.

33. A production process for forming moulded thermoset materials, wherein the process comprises the following steps: (i) providing a mould for moulding a sheet of thermoset material, wherein the mould comprises an elastomeric material; (ii) providing a first shaped substrate; (iii) placing a surface of a first sheet of a phenolic thermoset material into contact with a surface of the mould and placing the first sheet of phenolic thermoset material and the mould on the first shaped substrate; (iv) applying a vacuum such that the first sheet of thermoset material is forced against the surface of the mould, and such that the first sheet of thermoset material and the mould conform to the shape of the first shaped substrate and the first sheet of thermoset material is at least partially cured; (v) providing a second sheet of a phenolic thermoset material, and providing a second shaped substrate, different from the first shaped substrate; and (vi) repeating steps (iii) and (iv) using the mould from part (i) and the second sheet of a phenolic thermoset material and the second shaped substrate from part (v).

34. A process according to claim 33, wherein the process is as defined in any one of claims 2 to 30.

35. A vacuum forming process for moulding a thermoset material, wherein the process comprises the following steps: (i) providing a mould for moulding a sheet of thermoset material, wherein the mould comprises an elastomeric material; (ii) placing a sheet of SMC into contact with a surface of the mould; (iii) applying a vacuum such that the sheet of thermoset material is forced against the surface of the mould, and such that the sheet of thermoset material is at least partially cured; wherein the sheet of SMC is pre-treated prior to step (iii) with a viscosity controlling agent such that the SMC sheet at least partially absorbs the viscosity controlling agent.

36. A process according to claim 35, wherein the viscosity controlling agent is selected from one or more of butanol, chloroform, ethanol, water, acetonitrile, hexane, and isopropyl alcohol.

37. A process according to claim 36, wherein the viscosity controlling agent is water.

38. A process according to any one of claims 35 to 37, wherein the process is as defined in any one of claims 2 or 7 to 30.

39. A process according to any preceding claim, further comprising incorporating the moulded thermoset material into an article.

40. An article comprising moulded thermoset material produced by a process according to any one of claims 1 to 37.

41. A kit of parts comprising: (i) a mould comprising an elastomeric material; (ii) a shaped substrate; and (iii) means for applying a vacuum to force the mould against the surface of the shaped substrate such that a sheet of thermoset material may be moulded between the mould and the shaped substrate.

42. A kit according to claim 41, wherein the elastomeric material is as defined in any one of claim 8 or 9.

43. A kit according to claim 41 or claim 42, wherein the shaped substrate comprises a layer of porous material as defined in any one of claims 19 to 24.

44. Use of a process according to any one of claims 1 to 39 to produce an article comprising moulded thermoset material.

Description

[0235] The present invention will now be described by way of example, with reference to the accompanying drawings, in which:

[0236] FIG. 1 shows a schematic cross-sectional view of an arrangement of components including a particulate material in the process of the present invention;

[0237] FIG. 2 shows a schematic cross-sectional view of the arrangement of FIG. 1 after vacuum is applied;

[0238] FIG. 3 shows a schematic cross-sectional view of an arrangement of components including a foam substrate in the process of the present invention;

[0239] FIG. 4 shows a schematic cross-sectional view of an arrangement of components including a shaped foam substrate in the process of the present invention; and

[0240] FIG. 5 shows a photograph of part of a composite produced in accordance with the vacuum forming process of the present invention.

[0241] FIG. 1 shows a schematic cross-sectional view of an arrangement of a thermoset material 10 and a mould 12. In this example, particulate material 14 is provided between the mould 12 and the thermoset material 10, however such particulate material may not be required.

[0242] A frame 11 is provided around the components and a sheet of flexible material 16, for example a vacuum bag, is attached to the frame 11. A vacuum is created by withdrawing air via an outlet 18, for example using a vacuum pump.

[0243] As shown in FIG. 2, when a vacuum is applied the mould 12, the thermoset material 10, and in this case the particulate material 14, are forced together by the sheet 16 as a result of the applied vacuum via outlet 18.

[0244] As shown in FIGS. 1 and 2, the mould has an undercut in its shape. The use of an elastomeric mould 12 allows the moulded and cured thermoset material to be removed from the mould more easily after the moulding step.

[0245] The particulate material 14 is embedded in the surface of the thermoset material 10 during the vacuum step. It will be appreciated that in various examples, the particulate material 14 may only be applied to certain areas of the mould or thermoset material 10 or different particulate materials may be applied to different areas.

[0246] FIG. 3 shows an arrangement where a foam substrate 20 is arranged on the rear surface of the thermoset material 10 opposite the surface facing the mould 12. A vacuum may be applied as shown in FIG. 2 to produce a composite having a moulded surface formed from the cured thermoset material, where the thermoset material is bonded to the foam substrate 20 on the opposing side.

[0247] FIG. 4 shows another arrangement where a mould 13 is arranged over a thermoset material 10 and a shaped foam substrate 22 is provided on the rear surface of the thermoset material 10. Although a different mould shape 13 is shown in FIG. 4, this is purely by way of example and it will be appreciated that any suitable mould shape may be used, for example a mould having undercut such as is shown in FIGS. 1 to 3. A vacuum may be applied as shown in FIG. 2 to produce a moulded and cured thermoset that this shaped to the contours of and bonded to the foam substrate.

[0248] Although no particulate material is shown in FIG. 3 or FIG. 4, it will be appreciated that particulate material or other surface effects as described herein may also be included in these examples.

[0249] With reference to the embodiments of FIGS. 1 to 4, as described herein, the thermoset material, the mould, the foam substrate or the particulate material may be heated prior to the vacuum step to induce curing of the thermoset material and to allow flow of the thermoset material around the particulate material 14 or into pores of the foam substrate 20, 22. The heating may also be conducted during the vacuum step as described herein.

[0250] It will be appreciated that the accompanying Figures are only illustrative and the relative scale of the components may be different in practice.

[0251] FIG. 5 shows a photograph of a composite produced by a vacuum forming process in accordance with the present invention. The composite comprises a thermoset material bonded to a foam substrate, where the thermoset material has been moulded to have a brick pattern by an elastomeric mould during the vacuum moulding process. The substrate has a profiled surface and the thermoset material and the mould have adapted to the shape of the substrate to produce a moulded pattern across the surface of the thermoset material, which conforms to the uneven surface of the substrate. It will be appreciated that the same mould could be re-used with other different shaped substrates without requiring a new mould to be provided each time.