Method of preparing a lignocellulosic material for the manufacture of a finished product

• US 6,451,153 B1
• Filed: 07/15/1997
• Issued: 09/17/2002
• Est. Priority Date: 10/31/1994
• Status: Expired due to Fees

• Current Assignee: Windsor Technologies Incorporated
• Original Assignee: Tower Technology, Inc.
• Inventors: Symons, Michael Windsor
• Primary Examiner(s): Gallagher, John J.
• Application Number:
  US08/849,008
• Time in Patent Office: 1,890 Days
• Field of Search: 156/316, 156/276, 156/281, 427/214, 427/325, 427/399, 428/326, 428/420
• US Class Current: 156/276
• CPC Class Codes: B29C 70/58 comprising fillers only , e.g. particles, powder, beads, flakes, spheres B29C70/025 takes precedence, agglomerating hollow spheres to produce synthetic foam B29C70/66; compounding ingredients per se C08K
• CPC Class Codes: B29C 70/606 and with one or more layers of non-plastics material or non-specified material, e.g. supports
• CPC Class Codes: B29K 2105/0014 Catalysts
• CPC Class Codes: B29K 2503/08 Mineral aggregates, e.g. sand, clay or the like
• CPC Class Codes: B29K 2709/00 Use of inorganic materials not provided for in groups B29K2703/00 - B29K2707/00, for preformed parts, e.g. for inserts
• CPC Class Codes: B32B 3/12 characterised by a layer of regularly- arranged cells, e.g. a honeycomb structure
• CPC Class Codes: C04B 20/023 Chemical treatment
• CPC Class Codes: C04B 20/1029 Macromolecular compounds
• CPC Class Codes: C04B 26/02 Macromolecular compounds
• CPC Class Codes: C04B 26/08 containing halogen
• CPC Class Codes: C08H 8/00 Macromolecular compounds derived from lignocellulosic materials pretreatment thereof B27N
• CPC Class Codes: C08L 2666/02 Organic macromolecular compounds, natural resins, waxes or and bituminous materials
• CPC Class Codes: C08L 97/02 Lignocellulosic material, e.g. wood, straw or bagasse manufacture of articles made from lignocellulosic material by dry processes B27N
• CPC Class Codes: Y10T 428/253 Cellulosic [e.g., wood, paper, cork, rayon, etc.]
• CPC Class Codes: Y10T 428/31536 Including interfacial reaction product of adjacent layers

Abstract

A method of preparing particles of a lignocellulosic material for the manufacture of a finished product, such as a particle board, includes the steps of chemically modifying the lignocellulosic material by impregnating the lignocellulosic material with a suitable anhydride in a non-aqueous solvent; applying to the particles of lignocellulosic material an adhesion promoter to promote the adherence of a thermoplastic resin to the surfaces of the particles of lignocellulosic material; and applying to the particles a thermoplastic resin in dry powder form, so that after the application of the adhesion promoter, the thermoplastic resin adheres to the surfaces of the particles of lignocellulosic material, the thermoplastic resin having been surfaced modified by irradiation or by fluorination; and removing any solvent present.

Claims

1. A method of preparing particles of a lignocellulosic material for the manufacture of a finished product includes the steps of:

(a) chemically modifying the lignocellulosic material by impregnating the lignocellulosic material with an impregnating composition comprising a dicarboxylic anhydride or a tricarboxylic anhydride dissolved in a suitable non-aqueous solvent;

(b) applying to the particles an adhesion promoter to promote the adherence of a thermoplastic resin to the surfaces of the particles of lignocellulosic material;

(c) applying to the particles a thermoplastic resin in dry powder form, so that after the application of the adhesion promoter, the thermoplastic resin adheres to the surfaces of the particles of lignocellulosic material, the thermoplastic resin having been surface modified by irradiation or by fluorination; and

(d) after step (a) or step (c), removing the solvent.

2. A method according to claim 1 wherein the adhesion promoter is included in the impregnating composition of step (a).

3. A method according to claim 1 wherein the adhesion promoter is applied to the particles after step (a).

4. A method according to claim 2 or claim 3 wherein the solvent is recovered after step (c).

5. A method according to claim 1 wherein the solvent is recovered after step (a) and thereafter the adhesion promoter is applied to the particles of lignocellulosic material in a solvent for the adhesion promoter.

6. A method according to claim 1 wherein the adhesion promoter is applied to the particles of thermoplastic resin before step (c).

7. A method according to any one of claim 1 wherein the anhydride is selected from the group consisting of maleic anhydride, phthalic anhydride, succinic anhydride, tetrahydrophthalic anhydride and trimellitic anhydride.

8. A method according to any one of claim 1 wherein the solvent for the anhydride is selected from the group consisting of methyl acetate, ethyl acetate, methyl ethyl ketone, benzene, trichloroethylene and dichloromethane.

9. A method according to claim 8 wherein the solvent for the anhydride is dichloromethane.

10. A method according to any one of claim 1 wherein the impregnating composition contains from 0,25% to 25% inclusive of the anhydride by weight of the impregnating composition.

11. A method according to any one of claim 1 wherein the adhesion promoter is selected from the group consisting of petroleum resins, hydrocarbon resins, coumarone indene resins,

thermoplastic rubbers, styrene butadiene resins, styrene acrylate resins, chlorinated rubbers, phenolic resins, solvent soluble thermoplastic resins, lignocellulosic derived gums or rosins, solvent swellable celluloses, phenol formaldehyde novolac resins, urethane elastomers, resinous tackifiers, bitumen, coal tar, asphalt, and pitch.

12. A method according to any one of claim 1 wherein the adhesion promoter is applied to the particles in an amount of from 0,1% to 25% inclusive of the adhesion promoter by weight of the particles of lignocellulosic material.

13. A method according to any one of claim 1 wherein the thermoplastic resin comprises an irradiated cross-linkable thermoplastic resin in dry powder form, which resin has been subjected to gamma irradiation whilst in dry powder form, the resin being selected from the group consisting of polyvinyl chloride, linear low density polyethylene, low density polyethylene and high density polyethylene.

14. A method according to any one of claim 1 wherein the thermoplastic resin comprises a thermoplastic resin in dry powder form which has been fluorinated, the resin being selected from the group consisting of polyvinyl chloride, polyethylene and polypropylene.

15. A method according to any one of claim 1 wherein in step (c) the particles of lignocellulosic material are resinated with from 1% to 300% inclusive of the thermoplastic resin by weight of the lignocellulosic material.

16. A method according to any one of claim 1 wherein in step (a) the impregnating composition includes an isocyanate thermosetting resin dissolved in a suitable compatible solvent.

17. A method according to claim 16 wherein the solvent for the isocyanate thermosetting resin is the same as the solvent for the impregnating composition.

18. A method according to claim 16 wherein the impregnating composition contains the isocyanate thermosetting resin in an amount of from 0,25% to 50% inclusive of the isocyanate thermosetting resin by weight of the impregnating composition.

19. A method according to any one of claim 1 wherein in step (c), there is also applied to the particles a dry powder novolac thermosetting resin and if necessary a catalyst therefor so that the dry powder novolac thermosetting resin adheres to the surfaces of the particles of lignocellulosic material.

20. A method according to any one of claim 1 wherein in step (c) there is also applied to the particles a wax either in dry particulate form or dissolved in a suitable solvent, so that the wax adheres to or impregnates the surfaces of the particles of lignocellulosic material.

21. A process of making a particle board from particles of a lignocellulosic material treated according to the method of any one of claim 1, which process includes the steps of:

(i) impregnating a sheet or sheets of a lignocellulosic material with a composition comprising a thermosetting resin, an extending liquid for the thermosetting resin and where necessary a catalyst for the thermosetting resin;

(ii) recovering the extending liquid;

(iii) placing on one or both sides of a layer of the particles of lignocellulosic material, the impregnated sheet or sheets of lignocellulosic material to form a composite; and

(iv) compressing the composite with heating in a suitable press to allow the resin present to polymerise, and to allow any wax or convertible resin present to melt and flow, and to allow the thermosetting resin in the impregnated sheet or sheets to polymerise and to bond, and all to set to form the particle board.

22. A process according to claim 21 wherein in step (iv) the composite is compressed and heated in a suitable press at a temperature between 120°

C. and 250°

C. inclusive and at a pressure of from 2 to 70 kg/cm² inclusive.