Method and apparatus for forming an article and an article formed thereby
A method for forming an article in which thermoplastics materials are used as the binding agent. Materials ( 21 ) are shredded in a shredder ( 1 ), compressed in a compressing chamber ( 15 ) and moulded in a moulding chamber ( 16, 17, 19, 20, 26, 27 ). The thermoplastics material is heated whilst the material is held under compression and then cooled to bind the material together. In one embodiment superheated steam is supplied via tubes ( 31 ) having apertures there along. In another embodiment superheated steam is supplied via apertures in side walls of the mould ( 58, 59 ). Blocks ( 62, 72 ) formed by the method and apparatus of the invention may find application as construction materials etc. and have good structural, thermal and acoustic properties.
1. A method of forming an article comprising the steps of:
i) introducing into a chamber material to be formed containing a sufficient amount of thermoplastics material to bind the material together;
ii) compressing the material within the chamber in one direction and then in a second direction, transverse to the first direction, so that it occupies a reduced volume;
iii) inputting sufficient energy to melt sufficient thermoplastics material substantially throughout the material to bind the material together when cooled, and
iv) releasing an article produced from the chamber.
2. A method as claimed in claim 1 wherein the material is subsequently compressed in a third direction transverse to the first and second directions.
3. A method as claimed in claim 1 , wherein superheated steam is supplied to the chamber from a super heated steam source.
4. A method as claimed in claim 3 wherein the superheated steam is supplied through one or more side wall of the chamber.
5. A method as claimed in claim 3 wherein the superheated steam is supplied via tubes supplied with superheated steam having apertures along their length which are inserted into the chamber in step iii.
6. A method as claimed in claim 1 wherein fluid within the chamber is heated by a microwave energy source to generate steam.
7. A method as claimed in claim 6 wherein water is injected into the chamber before microwave energy is supplied.
8. A method as claimed in claim 1 wherein the material is shredded prior to being placed within the chamber.
9. A method as claimed in claim 8 where the material is shredded into strips of about 10 to 20 mm in width.
10. A method as claim in claim 1 wherein the thermoplastics material is waste plastics.
11. A method as claimed in claim 10 wherein the thermoplastics material is a mixture of different types of waste plastics.
12. A method as claimed in claim 10 wherein the thermoplastics material includes PETE and/or polyethylene.
13. A method as claimed in claim 10 wherein the other material to be formed includes at least one of sawdust, wood chips, fibres and papers.
14. A method as claimed in claim 1 wherein the article is cooled by introducing liquid to the chamber prior to release of the article in step iv.
15. A method as claimed in claim 1 where the article is cooled by introducing air to the chamber prior to release of the article in step iv.
16. A method as claimed in claim 1 wherein the article is cooled by releasing it from the chamber into a fluid bath.
17. A method of forming an article comprising the steps of:
i) introducing into a chamber material to be formed containing a sufficient amount of thermoplastic material to bind the material together;
ii) compressing the material within the chamber so that it occupies a reduced volume;
iii) introducing sufficient superheated steam into the chamber to melt sufficient thermoplastics material substantially throughout the material to bind the material together when cooled; and
iv) releasing an article produced from the chamber.
18. A method as claimed in claim 17 wherein the material is compressed in one direction and then in a second direction transverse to the first direction.
19. A method as claimed in claim 18 wherein the material is subsequently compressed in a third direction transverse to the first and second directions.
20. A method as claimed in claim 17 wherein the material is shredded prior to being supplied to the chamber.
21. A method as claimed in claim 20 wherein the material is shredded into strips of about 10 to 20 mm in width.
22. A method as claimed in claim 21 wherein the strips are shredded so as to have rough edges which interlock when compressed.
23. A method as claimed in claim 20 wherein the shredded material is washed and dried prior to being supplied to the chamber.
24. A method as claimed in claim 17 wherein the thermoplastics material is waste plastics.
25. A method as claimed in claim 24 wherein the thermoplastics material is a mixture of different types of waste plastics.
26. A method as claimed in claim 24 wherein the thermoplastics material includes PETE and/or polyethylene.
27. A method as claimed in claim 24 wherein the material to be formed includes at least one of sawdust, wood chip, fiber and paper.
28. A method as claimed in claim 17 wherein the article is cooled by supplying cooling fluid to the chamber prior to releasing the article from the chamber.
29. A method as claimed in claim 17 wherein the article is cooled by introducing air into the chamber prior to releasing the article from the chamber.
30. A method as claimed in claim 17 wherein the article is cooled by releasing it from the chamber into a fluid bath.
31. A method as claimed in claim 17 wherein the superheated steam is supplied to the chamber via openings provided in one or more side wall of the chamber.
32. A method as claimed in claim 17 wherein the superheated steam is supplied by inserting tubes into the chamber having apertures along their length for delivering superheated steam into the chamber at locations such as to ensure sufficient thermoplastics materials is melted throughout the article to bind the article together when it cools.
33. A method as claimed in claim 17 wherein superheated steam at a temperature between 200° C. to 400° C. is supplied to the chamber in step iii.
34. A method as claimed in claim 33 wherein the superheated steam is at a temperature of between 260° C. to 320° C.
35. A method as claimed in claim 33 wherein the superheated steam is at a temperature between 280° C. to 300° C.
36. A method as claimed in claim 1 wherein a pressure of between 5 psi to 100 psi is maintained within the chamber during step iii.
37. A method as claimed in claim 36 where the pressure is maintained at between 5 to 60 psi.
38. A method as claimed in claim 36 when the pressure is maintained at between 10 to 20 psi.
39. A method as claimed in claim 17 wherein superheated steam is supplied into the chamber in step iii for a period of between 10 seconds to 5 minutes.
40. A method as claimed in claim 39 wherein the period is between 10 to 60 seconds.
41. A method as claimed in claim 39 wherein the period is between 10 to 20 seconds.
42. A method as claimed in claim 17 wherein superheated steam at a temperature of between 260° C. to 320° C. is supplied to the chamber for a period of between 10 to 20 seconds at a pressure of between 5 to 25 psi.
43. A method as claimed in claim 17 wherein superheated steam at a temperature of about 300° C. is supplied to the chamber for a period of about 15 seconds at a pressure of between 5 to 25 psi.
44. A method as claimed in claim 17 wherein superheated steam at a temperature of about 300° C. is supplied into the chamber for a period of between 10 to 15 seconds and a pressure of about 15 psi is maintained in the chamber.
45. A method as claimed in claim 1 wherein the material is reduced in volume by a factor of between 5:1 to 25:1.
46. A method as claimed in claim 45 wherein the material is reduced in volume by a factor of between 10:1 to 20:1.
47. A method as claimed claim 1 wherein the material includes up to 20% of material that is not thermoplastic material.
48. A method as claimed in claim 1 wherein the material includes up to 10% of material that is not thermoplastic material.
49. A method as claimed in claim 2 wherein the material is compressed by substantially the same amount in each direction of compression.