METHOD OF SHAPING A CURED THERMOSETTING RESIN

Abstract

The present invention relates to a method of shaping a cured thermosetting resin substrate, and more particularly to a method of shaping a cured thermosetting resin using electromagnetic radiation, said method comprises providing a cured thermosetting resin substrate; providing a confined temperature controlling environment; placing the cured thermosetting resin substrate in the confined temperature controlling environment; providing a source of electromagnetic radiation; irradiating the cured thermosetting resin substrate in the confined temperature controlling environment; and shaping the irradiated thermosetting resin substrate.

Claims

1. A method of shaping a cured thermosetting resin substrate, the method comprising the steps of: i. providing a cured thermosetting resin substrate; ii. providing a confined temperature controlling environment; iii. placing the cured thermosetting resin substrate in the confined temperature controlling environment; iv. providing a source of electromagnetic radiation; v. irradiating the cured thermosetting resin substrate in the confined temperature controlling environment; and vi. shaping the irradiated thermosetting resin substrate.

2. A method according to claim 1, wherein the temperature controlling environment is in the form of a gas, vapour, liquid or gel, or a combination thereof.

3. A method according to claim 2, wherein the temperature controlling environment is a liquid.

4. A method according to claim 3, wherein the liquid has a boiling point of 100° C. or greater.

5. A method according to claim 3 or 4, wherein the liquid is selected from ethylene glycol, butanol, toluene, decane and water, as well as combinations thereof.

6. A method according to claim 5, wherein the liquid is water.

7. A method according to any one of claims 3 to 6, wherein the liquid is heated to a temperature of 20 to 95° C., such as 60 to 90° C., during irradiating.

8. A method according to any one of the preceding claims, wherein the cured thermosetting resin is at least substantially immersed in the confined temperature controlling environment.

9. A method according to any one of the preceding claims, wherein the cured thermosetting resin substrate is completely immersed in the confined temperature controlling environment.

10. A method according to any preceding claim, wherein the cured thermosetting resin is selected from a phenolic resin, polyester, acrylic resin, vinyl ester, polyurethane, an epoxy resin and a sheet-form moulding material.

11. A method according to claim 10, wherein the sheet-form moulding material is a SMC (sheet moulding compound).

12. A method according to claim 10, wherein the thermosetting resin is selected from phenolic resin, polyester and polyurethane.

13. A method according to any preceding claim, wherein the cured thermosetting resin further comprises one or more fillers.

14. A method according to claim 13, wherein the one or more fillers are chemically inert.

15. A method according to claim 13, wherein the filler may be selected from clays, clay minerals, talc, graphite, calcium carbonate, gypsum, alumina, silicates, vermiculite, refractories, solid or hollow glass microspheres, fly ash, coal dust, wood flour, grain flour, nut shell flour, silica, mineral fibres such as finely chopped glass fibre and finely divided asbestos, chopped fibres, finely chopped natural or synthetic fibres, ground plastics and resins whether in the form of powder or fibres, e.g. reclaimed waste plastics and resins, pigments such as powdered paint and carbon black, and starches.

16. A method according to any one of the preceding claims, wherein the cured thermosetting resin is foamed.

17. A method according to claim 15, wherein the cured thermosetting resin comprises an open-cell structure.

18. A method according to claim 17, wherein at least 50% of the available pore volume of the cured thermosetting resin is filled with the temperature controlling environment.

19. A method according to claim 18, wherein at least 80% of the available pore volume of the cured thermosetting resin is filled with the temperature controlling environment.

20. A method according to claims 18 and 19, wherein at least 90% of the available pore volume of the cured thermosetting resin is filled with the temperature controlling environment.

21. A method according to any preceding claim, wherein the electromagnetic radiation is selected from microwave, RF, ultra-sound and infrared.

22. A method according to claim 21, wherein the electromagnetic radiation is microwave.

23. A method according to claim 22, wherein the microwave radiation has a wavelength of 1 mm to 1 m.

24. A method according to claim 23, wherein the microwave radiation has a wavelength of 10 to 50 cm.

25. A method according to any one of claims 22 to 24, wherein the microwave radiation has a frequency of 300 GHz to 300 MHz.

26. A method according to claim 25, wherein the microwave radiation has a frequency of 25 GHz to 450 MHz.

27. A method according to any one of claims 22 to 26, wherein the microwave radiation transmits a power of 500 W to 120 kW.

28. A method according to claim 27, wherein the source of microwave radiation transmits a power of 750 W to 100 kW, such as 950 W to 75 kW.

29. A method according to any preceding claim, wherein the cured thermosetting resin is irradiated for less than 30 minutes.

30. A method according to claim 29, wherein the cured thermosetting resin is irradiated for less than 10 minutes.

31. A method according to any preceding claim, wherein the cured thermosetting resin is irradiated for at least 30 seconds, preferably for at least one minute.

32. A method according to any preceding claim, wherein the steps of irradiating the cured thermosetting resin and shaping the irradiated thermosetting resin substrate occur simultaneously.

33. A method according to any preceding claim, wherein the cured thermosetting resin substrate is pre-treated prior to being irradiated.

34. A method according to claim 33, wherein pre-treatment comprises cooling the thermosetting resin substrate.

35. A method according to any preceding claim, wherein the step of shaping comprises use of a mould.

36. A method according to any preceding claim, wherein the step of shaping comprises thermoforming.

37. A method according to any preceding claim, wherein the cured thermosetting resin substrate is pre-shaped, and the method comprises changing the pre-shaped shape during shaping.

38. A method of shaping a cured thermosetting resin substrate, the method comprising the steps of: i. providing a cured thermosetting resin substrate; ii. providing a fluid as a temperature controlling environment; iii. at least partially immersing the cured thermosetting resin substrate in the fluid; iv. providing a source of electromagnetic radiation; v. irradiating the at least partially immersed cured thermosetting resin substrate; and vi. shaping the irradiated thermosetting resin substrate.

39. A method of shaping a cured open-cell thermosetting foam resin substrate, the method comprising the steps of: i. providing a cured thermosetting foam resin substrate; ii. providing a liquid as a temperature controlling environment; iii. at least partially saturating the open-cells of the cured thermosetting foam resin substrate in the liquid; iv. providing a source of electromagnetic radiation; v. irradiating the at least partially saturated cured open-cell thermosetting foam resin substrate; and vi. shaping the irradiated open-cell thermosetting foam resin substrate.

40. A method of recycling a pre-shaped cured thermosetting resin substrate, the method comprising the steps of: i. providing a pre-shaped cured thermosetting resin substrate; ii. providing a confined temperature controlling environment; iii. placing the pre-shaped cured thermosetting resin substrate in the confined temperature controlling environment; iv. providing a source of electromagnetic radiation; v. irradiating the pre-shaped cured thermosetting resin substrate in the confined temperature controlling environment; and vi. re-shaping the irradiated thermosetting resin substrate.

41. A cured thermosetting resin shaped by a method according to any one of the preceding claims.

42. A cured thermosetting resin according to claim 41, wherein the resin has a substantially open-celled structure.

43. A cured thermosetting resin according to claim 41 or claim 42, wherein the resin is a sheet moulding compound.

44. Use of electromagnetic radiation for shaping a cured thermosetting resin.

45. Use of electromagnetic radiation for recycling a pre-shaped cured thermosetting resin.

46. Use according to claim 44 and claim 45, wherein the cured thermosetting resin is irradiated whilst in a temperature controlling environment, such as water.

47. Use according to any one of claims 44 to 46, wherein the electromagnetic radiation is selected from microwave, RF, ultra-sound and infrared.

48. Use according to any one of claims 44 to 46, wherein the electromagnetic radiation is microwave.

49. Use according to any one of claims 44 to 48, comprising use of a method in accordance with any one of claims 1 to 40.

50. An apparatus for preparing a cured thermosetting resin for shaping comprising: (i) A container for receiving a cured thermosetting resin; (ii) A source of temperature controlling environment; and (iii) A controllable electromagnetic radiation source.

Description

EXAMPLES

Example 1

[0203] Example 1 illustrates the effect of microwave radiation alone on a thermosetting resin substrate where no temperature controlling environment is present.

[0204] In this example, a cured open-celled phenolic resin foam, produced in accordance with the disclosure above and available from Acell Holdings Limited, of dimensions 25 cm×25 cm×2 cm was placed in a domestic microwave providing a power of 800 W. The cured open-celled phenolic resin foam was irradiated for ten minutes. The surface temperature of the substrate was 90° C. as measured using a thermocouple, and the temperature of the water about 85° C. (for reference, similar temperatures were seen in all of the Examples).

[0205] The resulting cured phenolic foam had darkened in colour. In addition, the foam block had further hardened, and therefore was more brittle. Accordingly, the irradiated phenolic foam could not be re-shaped.

Example 2

[0206] Example 2 illustrates a method of the present invention.

[0207] In this example, an identical sample of the cured open-celled phenolic resin as used in Example 1 was provided having the same dimensions. The cured open-celled phenolic foam was immersed in water, which acted as the temperature controlling environment. The cured open-celled phenolic foam was immersed and saturated in the water such that 80% of the available pore volume was filled with water.

[0208] The saturated cured open-celled phenolic foam was then placed in a domestic microwave providing a power of 800 W and was irradiated for ten minutes.

[0209] The resulting irradiated cured open-celled phenolic foam was removed from the microwave, the water allowed to drain, and was placed on a pipe for shaping—all within about 30 seconds. The irradiated cured open-celled phenolic foam was shaped to the diameter of the pipe by hand. Upon cooling, and after 2 minutes, the new shape of the cured open-celled phenolic foam was fixed.

[0210] This example clearly demonstrates that the presence of a temperature controlling environment is essential to the process, and that the shaping of a cured thermoset resin can be achieved by the method of the present invention.

Example 3

[0211] Example 3 also illustrates a method of the present invention.

[0212] In this example, an identical sample of the cured open-celled phenolic resin as used in Example 1 was provided having the same dimensions. The cured open-celled phenolic foam was immersed in water, which acted as temperature controlling environment. The cured open-celled phenolic foam was immersed in the water and saturated such that 80% of the available pore volume of the cured open-celled phenolic foam was filled with water.

[0213] The saturated cured open-celled phenolic foam was then placed in a domestic microwave providing a power of 800 W and was irradiated for ten minutes.

[0214] The resulting irradiated cured open-celled phenolic foam was removed from the microwave, the water allowed to drain, and was shaped—all within about 30 seconds. For this example, the substrate was shaped by twisting the corners of the substrate by hand in opposite directions. The phenolic foam retained the new shape upon cooling.

[0215] This example also illustrates that the method of the present invention enables the shaping of cured thermosetting resin substrates.

Example 4

[0216] Example 4 illustrates the effect of heating a cured thermosetting resin in the presence of a temperature controlling environment but without the use of electromagnetic radiation.

[0217] In this example, an identical sample of the cured open-celled phenolic resin as used in Example 1 was provided having the same dimensions The cured open-celled phenolic resin was placed in boiling water and maintained in this state for 10 minutes.

[0218] The resulting cured open-celled phenolic foam was removed from the boiling water, the water allowed to drain, and shaping was attempted—all within about 30 seconds. However, the cured open-celled phenolic foam could not be shaped.

[0219] This demonstrates that the effect of shaping a cured thermosetting resin cannot be attributed to the application of heat alone, nor to the presence of the temperature controlling environment alone, but that the present invention requires the use of electromagnetic radiation.

Example 5

[0220] This example further illustrates the method of the present invention, even where a thermosetting resin substrate has already been previously shaped.

[0221] In this example, the shaped product from Example 2 was used.

[0222] The shaped product from Example 2 was immersed in water, which acted as the temperature controlling environment. The shaped product was immersed and saturated in the water such that 80% of the available pore volume was filled with water.

[0223] The saturated shaped product was then placed in a domestic microwave providing a power of 800 W and was irradiated for ten minutes.

[0224] The resulting irradiated shaped product was removed from the microwave, the water allowed to drain, and was placed on a pipe for re-shaping in the opposite direction—all within about 30 seconds. The shaped product was re-shaped by hand to the diameter of the pipe. Upon cooling, and after 2 minutes, the new re-shape of the product from Example 2 was fixed.

[0225] This example clearly demonstrates that re-shaping of cured thermosetting resin substrates is possible, even where the substrate has already been shaped using a method in accordance with the present invention.

Example 6

[0226] Example 6 demonstrates the traditional effect of microwave radiation on a cured SMC resin substrate.

[0227] In this example, the process of Example 1 was filed except a cured sample of sheet moulding compound (SMC) known as Menzolit® SMC 0650 (polyester) was used. The dimensions of the cured sample were approximately 25 cm×25 cm×2 mm. The cured sample was placed in a domestic microwave providing a power of 800 W. The cured sample was irradiated for ten minutes.

[0228] After irradiating, the sample was placed on a pipe for shaping but could not be shaped.

Example 7

[0229] Example 7 illustrates the method of the present invention as applied to cured SMC resins.

[0230] The cured SMC sample was immersed in water, which acted as the temperature controlling environment. The immersed cured SMC resin sample was then placed in a domestic microwave providing a power of 800 W and was irradiated for ten minutes.

[0231] The resulting irradiated cured SMC resin sample was removed from the microwave and shaped on a pipe within 30 seconds of completion of irradiation. The cured SMC resin sample was shaped to the diameter of the pipe by hand. The cured SMC sample retained the new shape upon cooling.

[0232] This example demonstrates that the process of the present invention can be applied generally to cured thermosetting resin substrates.

Example 8

[0233] Example 8 repeated the process of Example 3, except using a cured SMC (polyester) resin.

[0234] In this example, an identical sample of the cured SMC resin used in Example 6 was provided having the same dimensions, and was processed in accordance with the method of Example 3.

[0235] The resulting cured irradiated SMC resin sample was removed from the microwave and was shaped within 30 seconds of completion of the irradiation by twisting the corners of the irradiated cured SMC resin by hand in opposite directions. The SMC retained the new shape upon cooling.

Example 9

[0236] Example 9 repeated the process of Example 4, except using a cured SMC (polyester) resin.

[0237] In this example, an identical sample of the cured SMC resin used in Example 6 was provided having the same dimensions, and was processed in accordance with the method of Example 4.

[0238] The resulting cured SMC resin was removed from the boiling water and shaping was attempted—all within about 30 seconds. However, the cured SMC resin could not be shaped.

[0239] This demonstrates that the effect of shaping a cured thermosetting resin cannot be attributed to the application of heat alone, nor to the presence of the temperature controlling environment alone, but that the present invention requires the use of electromagnetic radiation, even where different thermosetting resins are used.

Example 10

[0240] Example 10 repeated the process of Example 5, except using a cured SMC (polyester) resin.

[0241] In this example, the shaped product of Example 7 was used, and was processed in accordance with the method of Example 5.

[0242] The resulting shaped cured SMC resin sample was removed from the microwave and was placed on a pipe for re-shaping in the opposite direction—all within about 30 seconds. The shaped product was re-shaped by hand to the diameter of the pipe. Upon cooling, and after 2 minutes, the new re-shape of the product from Example 7 was fixed.

[0243] This example clearly demonstrates that re-shaping of cured polyester thermosetting resin substrates is possible, even where the cured polyester material has already been shaped using a method in accordance with the present invention.

Example 11

[0244] Example 11 illustrates the method of the present invention as applied to cured polyurethane resins.

[0245] A cured polyurethane sheet containing a glass fibre mat was prepared using Axson PX 223/HT. The ratio of resin to fibre was 75:25.

[0246] A cured 25 cm×25 cm×4 mm sample was prepared and was immersed in water, which acted as the temperature controlling environment. The immersed cured polyurethane resin sample was then placed in a domestic microwave providing a power of 800 W and was irradiated for ten minutes.

[0247] The resulting irradiated cured polyurethane resin sample was removed from the microwave and shaped on a pipe within 30 seconds of completion of irradiation. The cured polyurethane resin sample was shaped to the diameter of the pipe by hand. The cured polyurethane sample retained the new shape upon cooling.

[0248] This example demonstrates again demonstrates that the process of the present invention is generally applicable to cured thermosetting resin substrates.