6 582 648

6,582,648 Title:

Method for manufacturing moulded bodies from crushed material and a binder hardenable by electron radiation

A particle board, a fiberboard or an oriented strand board (25) is formed by the process according to the invention from a mixture of a comminuted cellulose material and a binder, especially a synthetic resin containing an unsaturated oligimer, that is hardenable by electron radiation. The process of the invention includes first forming a loosely scattered layer (4) of the mixture, e.g. on a conveyor belt, then compressing the layer in a press device (16), after performing a pre-compression in a pre-press in Some embodiments, and rapid setting of the layer (4) by means of electron radiation from an electron radiation device (22). Unlike the known processes that only use a thermosetting binder, the inventive method is hindered neither by heat transfer to the center of the board nor by a non-uniform humidity profile. High quality boards may be produced at a high yield without splitting and these boards require no conditioning storage.

What is claimed is:

1. A process for manufacture of chipboard, fibreboard or oriented strand board from comminuted cellulose material, said process comprising the steps of: a) mixing thecomminuted cellulose material with a binder to form a mixture, said mixture containing from 1 to 30 percent by weight of said binder, based on dry mass of said cellulose material, said binder being hardenable by electron radiation; b) compressing saidmixture to form a molded body; and c) after the compressing, hardening said binder by said electron radiation to form the chipboard, fiberboard or oriented strand board from said molded body.

2. The process as defined in claim 1, wherein said compressing occurs so that said mixture is compressed beyond a nominal compression and springs back so as to have a nominal thickness and said hardening by said electron radiation takes placewhile said mixture is not under external pressure.

3. The process as defined in claim 1, wherein said hardening by said electron radiation takes place while said mixture is under a holding pressure that prevents spring back of said mixture.

4. The process as defined in claim 1, wherein said binder comprises a synthetic resin, said synthetic resin comprises an unsaturated oligomer, said unsaturated oligomer has polymerizable carbon-carbon double bonds and further comprisingincluding in said mixture from 1 to 20 percent by weight, based on said dry mass of said cellulose material, of a monomer for accelerating said hardening.

5. The process as defined in claim 4, wherein said unsaturated oligomer is selected from the group consisting of unsaturated polyester resins, ether acrylate resins, epoxide acrylate resins, urethane acrylate resins and unsaturated acrylateresins.

6. The process as defined in claim 4, wherein said monomer is included in said mixture an amount of from 1 to 5 percent by weight, based on said dry mass of said cellulose material, has a least one functional group and consists of an unsaturatedvinyl monomer.

7. A process for manufacture of chipboard, fiberboard or oriented strand board from comminuted cellulose material, said process comprising the steps of: a) mixing the comminuted cellulose material with a binder hardenable by electron radiationand with a form-stabilizing thermally hardenable binder to form a mixture; b) compressing said mixture to form a molded body; and c) during the compressing thermally partially hardening said form-stabilizing thermally hardenable binder; and d) afterthe compressing, additionally hardening said binder hardenable by said electron radiation to form the chipboard, fiberboard or oriented strand board from said molded body hardened by said form-stabilizing hardenable binder.

8. The process as defined in claim 7, wherein only an outer surface region of said mixture is thermally hardened during the thermally partially hardening.

9. The process as defined in claim 7, wherein said mixture contains from 0.5 to 20 percent by weight, based on dry mass of said cellulose material, of said form-stabilizing thermally hardenable binder and from 0.5 to 20 percent by weight, basedon said dry mass of said cellulose material, of said binder hardenable by said electron radiation.

10. The process as defined in claim 7, wherein said mixture contains from 1 to 10 percent by weight, based on dry mass of said cellulose material, of said form-stabilizing thermally hardenable binder from 1 to 10 percent by weight, based on saiddry mass of said cellulose material, of said binder hardenable by said electron radiation.

11. The process as defined in claim 7, wherein said form-stabilizing thermally hardenable binder is selected from the group consisting of phenol-formaldehyde resin, tannic resin, urea-formaldehyde resin, melamine-formaldehyde resin, and mixturesthereof.

12. The process as defined in claim 7, wherein said form-stabilizing thermally hardenable binder is an isocyanate resin.

13. The process as defined in claim 12, wherein said isocyanate resin is polymeric methyl diisocyanate.

14. The process as defined in claim 7, further comprising including in said mixture from 1 to 20 percent by weight, based on dry mass of said cellulose material, of a monomer for accelerating said hardening.

15. The process as defined in claim 14, wherein said monomer is included in said mixture an amount of from 1 to 5 percent by weight, based on said dry mass of said cellulose material, has at least one functional group and consists of anunsaturated vinyl monomer.

16. The process as defined in claim 7, wherein said binder hardenable by said electron radiation is contained in said mixture in an amount of from 1 to 30 percent by weight of said binder, based on dry mass of said cellulose material.

17. The process as defined in claim 7, wherein said binder hardenable by said electron radiation is a synthetic resin and said synthetic resin is selected from the group consisting of unsaturated polyester resins, ether acrylate resins, epoxideacrylate resins, urethane acrylate resins and unsaturated acrylate resins.

18. A process for manufacture of chipboard, fiberboard or oriented strand board from comminuted cellulose material, said process comprising the steps of: a) mixing the comminuted cellulose material with a binder hardenable by means of electronradiation and with a peroxide to form a starting mixture; b) then partially hardening the starting mixture under an external pressure and heating by means of a radical hardening process employing said peroxide to form a partially hardened molded body; and c) after the partially hardening, further hardening by means of electron radiation to form the chipboard, fiberboard or oriented strand board from said partially hardened molded body by means of the electron radiation.

19. The process as defined in claim 18, wherein said peroxide is an organic peroxide compound.

20. The process as defined in claim 18, wherein said binder hardenable by said electron radiation is contained in said starting mixture in an amount of from 1 to 30 percent by weight of said binder, based on dry mass of said cellulose material.

21. The process as defined in claim 18, wherein said binder hardenable by said electron radiation is a synthetic resin and said synthetic resin is selected from the group consisting of unsaturated polyester resins, ether acrylate resins, epoxideacrylate resins, urethane acrylate resins and unsaturated acrylate resins.

22. A process for manufacture of chipboard, fiberboard or oriented strand board from comminuted cellulose material, said process comprising the steps of: a) mixing the comminuted cellulose material with a binder hardenable by electron radiationto form a mixture; b) compressing said mixture to form a molded body having a thickness smaller than a final thickness of a final product of the process; and c) reducing pressure on the molded body so that the molded body attains the final thickness ofthe final product; and d) curing the binder by electron radiation.

23. The process as defined in claim 22, wherein said binder hardenable by said electron radiation is a synthetic resin and said synthetic resin is selected from the group consisting of unsaturated polyester resins, ether acrylate resins, epoxideacrylate resins, urethane acrylate resins and unsaturated acrylate resins.

24. The process as defined in claim 22, wherein said binder hardenable by said electron radiation is contained in said mixture in an amount of from 1 to 30 percent by weight of said binder, based on dry mass of said cellulose material.

25. The process as defined in claim 24, further comprising including in said mixture from 1 to 20 percent by weight, based on dry mass of said cellulose material, of a monomer for accelerating said hardening.

26. The process as defined in claim 25, wherein said monomer is included in said mixture an amount of from 1 to 5 percent by weight, based on said dry mass of said cellulose material, has at least one functional group and consists of anunsaturated vinyl monomer.