Claims
- 1. A method of preparing a porous structural unit which comprises:
- a step of putting a material including resin particles into a space formed by first and second molds,
- a step of producing a temperature difference between said first and second molds,
- a step of pressing said material with said molds, and
- a step of heating at least one of said molds to a temperature sufficient to soften said resin particles in said material, whereby a layer having a higher specific gravity produced at the high temperature side of said molds and a porous layer having a lower specific gravity produced at the low temperature side are formed in one piece,
- wherein said first mold has a heat capacity different from that of said second mold.
- 2. The method of preparing a porous structural unit according to claim 1, wherein said material including resin particles is a granular resin material.
- 3. The method of preparing a porous structural unit according to claim 1, wherein said layer having a higher specific gravity is a fusion layer.
- 4. The method of preparing a porous structural unit according to claim 3, wherein said fusion layer is air-permeable.
- 5. The method of preparing a porous structural unit according to claim 3, wherein said fusion layer is not air-permeable and said porous layer is air-permeable.
- 6. A method preparing a porous structural unit which comprises:
- a step of putting a material including resin particles into a space formed by first and second molds,
- a step of producing a temperature difference between said first and second molds,
- a step of pressing said material with said molds,
- a step of heating at least one of said molds to a temperature sufficient to soften said resin particles in said material, and
- a step of pressing said material or applying a shear stress to said material after heating whereby a layer having a higher specific gravity produced at the high temperature side of said molds and a porous layer having a lower specific gravity produced at the low temperature side are formed in one piece.
- 7. The method of preparing a porous structural unit according to claim 6, wherein said material including resin particles is a granular resin material.
- 8. The method of preparing a porous structural unit according to claim 6, wherein said layer having a higher specific gravity is a fusion layer.
- 9. The method of preparing a porous structural unit according to claim 8, wherein said fusion layer is air-permeable.
- 10. The method of preparing a porous structural unit according to claim 8, wherein said fusion layer is not air-permeable and said porous layer is air-permeable.
- 11. The method of preparing a porous structural unit according to claim 6, wherein said first mold has a heat capacity different from that of said second mold.
- 12. The method of preparing a porous structural unit according to claim 6, wherein a binder is incorporated in said material including resin particles.
- 13. A method of preparing a porous structural unit which comprises:
- a step of putting a material including resin particles into a space formed by first and second molds,
- a step of producing a temperature difference between said first and second molds,
- a step of pressing said material with said molds, and
- a step of heating at least one of said molds to a temperature sufficient to soften said resin particles in said material, whereby a layer having a higher specific gravity produced at the high temperature side of said molds and a porous layer having a lower specific gravity produced at the low temperature side are formed in one piece,
- wherein a binder is incorporated in said material including resin particles.
- 14. The method of preparing a porous structural unit according to claim 13, wherein said material including resin particles is a granular resin material.
- 15. The method of preparing a porous structural unit according to claim 13, wherein said layer having a higher specific gravity is a fusion layer.
- 16. The method of preparing a porous structural unit according to claim 15, wherein said fusion layer is not air-permeable.
- 17. The method of preparing a porous structural unit according to claim 15, wherein said fusion layer is not air-permeable and said porous layer is air-permeable.
Priority Claims (4)
Number |
Date |
Country |
Kind |
63-275688 |
Oct 1988 |
JPX |
|
1-104228 |
Apr 1989 |
JPX |
|
1-110996 |
Apr 1989 |
JPX |
|
1-208418 |
Aug 1989 |
JPX |
|
Parent Case Info
This is a division of application Ser. No. 07/429,496, filed on Oct. 31, 1989, now U.S. Pat. No. 5,108,833.
US Referenced Citations (18)
Foreign Referenced Citations (5)
Number |
Date |
Country |
53-113172 |
Oct 1978 |
JPX |
58-52132 |
Nov 1983 |
JPX |
62-1045 |
Jan 1987 |
JPX |
2184400 |
Jun 1987 |
GBX |
WO8606393 |
Nov 1986 |
WOX |
Non-Patent Literature Citations (3)
Entry |
Patent Abstracts of Japan, vol. 7, No. 55 (M-198)(1200), 5 Mar. 1983; & JP-A-57 201 633 (Nippon Denshin Denwa Kosha) Dec. 10, 1982. |
Patent Abstracts of Japan, vol. 8, No. 148 (M-308)(1585), 11 Jul. 1984; & JP-A-59 45 134 (Honda Giken Kogyo K.K.) Mar. 13, 1984. |
Patent Abstract of Japan, vol. 11, No. 123 (M-581)(2570), 17 Apr. 1987; p. 74 M 581; & JP-A-61 263 714 (Toshiba Corp.) Nov. 21, 1986. |
Divisions (1)
|
Number |
Date |
Country |
Parent |
429496 |
Oct 1989 |
|