COMBINED PROCESS OF HYDROLYSIS AND ESTERIFICATION OF WOOD

Abstract

A method of treating a cellulose-based material, for example wood and engineered wood is provided, wherein the process involves the following steps: selecting and placing the cellulose-based material in a treatment chamber; impregnating the cellulose-based material with an impregnating agent consisting of an aqueous solution comprising a fluid suitable for esterification; facilitating a hydrolysis process whereby the impregnating agent reacts resulting in the formation of esters and polyesters inside the cellulosed-based material.

Claims

1-8. (canceled)

9. A method of treating a cellulose-based material, for example wood and engineered wood, wherein the process involves the following: a) selecting and placing the cellulose based material in an impregnation chamber; b) impregnating the cellulose based material with a solution containing a monomer(s) to be esterified; c) placing the impregnated cellulose-based materials in a modification chamber; d) elevating the pressure in the modification chamber to above normal atmospheric pressure; e) heating the pressurized impregnated cellulose-based material to above ambient temperature until polymerization has been completed; and f) lowering the temperature to ambient temperature and lowering the pressure in the chamber to atmospheric pressure.

10. The method according to claim 9, wherein the cellulose-based material is wood or engineered wood, and spruce, fir, pine, beech, oak, birch, ash.

11. The method according to claim 9, wherein the fluid suitable for esterification is selected from the hydrocarbon group, where members are sorbitol, glycerol, Furfurylalcohol or xylitol.

12. The method according to claim 9, wherein the fluid suitable for esterification is DMDHEU.

13. The method according to claim 9, wherein the general chemical process for the esterification in the cellulose-based material is: ##STR00001##

14. The method according to claim 9, wherein for certain monomers and cellulose-based materials pressure is elevated to 5-20 Bar(A) and temperature to 100-175? C. in the modification chamber, which temperature and pressure is maintained during a holding phase lasting between 30 minutes and 12 hours, before cooling down again to ambient temperature and pressure release to ambient pressure.

15. The method according to claim 9, wherein the impregnating chamber and modification chamber is the same chamber and where step b) involves first establishing a vacuum for a predetermined period, followed by an increase in pressure.

16. A wood treated according to a method according to claim 9.

Description

AN EXAMPLE OF A COMBINED HYDROLYSIS AND FURFURYLAZATION PROCESS

[0043] This process can be done in different ways. In particular, it can be done in either a one step or a two-step process.

[0044] In the one step process, furfurylalcohol (FA) is vaporized within the chamber used for the hydrolysis process, so that the vaporized FA penetrates the wood cells simultaneously with the hydrolysis process.

[0045] In the two-step process, wood is first impregnated with an aqueous solution of FA in the first step. In the second step, the impregnated wood is hydrolyzed, and FA is polymerized simultaneously.

[0046] One step process.

[0047] First, the selected wood is arranged inside the chamber suitable for hydrolysis. The chamber can be heated, cooled and pressurized. In the bottom of the chamber, an aqueous solution of FA is placed in an open container, which can be heated to a point where FA evaporates.

[0048] Second, a vacuum of 0.2 Bar(A) for 30 min. is established, in order to empty the cells for atmospheric air and make room for FA vapor.

[0049] Third, the chamber is pressurized to 15 Bar(A)

[0050] Fourth, the chamber is heated to 150 deg. C. During the heating, the FA is heated until it evaporates, and is then circulated around the wood inside the chamber. Due to the high pressure, the FA vapors penetrate the empty wood cells.

[0051] Steps three and four can be combined in one step where pressure and heat are increased simultaneously. The preceding steps constitutes the impregnation process.

[0052] When the wood temperature reaches the desired temperature of 150 deg. C., the pressure and temperature is kept stable for two hours in a holding phase. During this phase, wood hemicelluloses is hydrolyzed into carboxylic acids and other residuals. Simultaneously, the vaporized FA inside the wood cells react with the carboxylic acids produced by the hydrolysis, resulting in the polymerization of the FA into a furan polymer.

[0053] The combined hydrolysis of hemicelluloses and furan polymer in the wood cells, results in increased durability against rot and fungi, increased dimensional stability and a number of other positive effects on the wood.

[0054] Fifth, the chamber is cooled down to ambient temperature, and

[0055] Sixth, the pressure on the chamber is brought down to atmospheric pressure, after which the chamber can be opened, and the modified wood taken out.

Two-Step Process

First StepImpregnation

[0056] First, the selected wood is placed in a chamber suitable for vacuum and pressure impregnation with aqueous solutions, and the door is closed and sealed.

[0057] The impregnation process can be in two different ways:

[0058] Example with full cells, meaning that a lower initial pressure is present, such that as the method progresses air is injected into the cells before the impregnating fluid is introduced and forced not the wood. When the pressure is lowered again (till normal atmospheric pressure) the trapped air will create a kick-back, forcing some of the fluid out again. In this manner impregnating fluid may be saved, without compromising the impregnation.

[0059] First, pressure in the chamber is elevated to 5 bar(A).

[0060] Second, the chamber is filled with the FA solution.

[0061] Third, pressure in the chamber is elevated to 15 bar(A).

[0062] Fourth, the pressure is kept for 2 hours, or until full uptake of the FA fluid is achieved.

[0063] Fifth, the chamber is emptied for FA fluid.

[0064] Sixth, a vacuum of 0.2 Bar(A) is established and maintained for 1 hour.

[0065] Example with empty cells, meaning that a pre-vacuum is established in order to extract any air from the cells of the wood. This is followed by forcing the impregnation fluid into the now empty cells.

[0066] First, a vacuum of 0.2 Bar(A) is established in the chamber.

[0067] Second, the chamber is filled with the FA solution.

[0068] Third, the pressure in the chamber is elevated to 15 Bar(A).

[0069] Fourth, the pressure is kept for 2 hours, or until full uptake of the FA fluid is achieved.

[0070] Fifth, the chamber is emptied for FA fluid.

[0071] Sixth, a vacuum of 0.2 Bar(A) is pulled and maintained for 1 hour.

Second StepHydrolysis and Polymerization

[0072] First, the selected wood is put inside the chamber suitable for hydrolysis. The chamber can be heated, cooled and pressurized. The door is closed and sealed.

[0073] Second, the pressure in the chamber is elevated to 15 Bar(A).

[0074] Third, the temperature is elevated to 150 deg. C.

[0075] Steps two and three can be combined in one step.

[0076] Fourth, when the wood temperature reaches the desired temperature of 150 deg. C., the pressure and temperature is kept stable for two hours in a holding phase. During this phase, wood hemicelluloses is hydrolyzed into carboxylic acids and other residuals. Simultaneously, the aqueous solution of FA inside the wood cells reacts with the carboxylic acids produced by the hydrolysis, resulting in the polymerization of the FA into a furan polymer.

[0077] The combined hydrolysis of hemicelluloses and furan polymer in the wood cells, results in increased durability against rot and fungi, increased dimensional stability and a number of other positive effects on the wood.

[0078] Fifth, the temperature in the chamber is brought down to ambient temperature, and

[0079] Sixth, the pressure in the chamber is brought down to atmospheric pressure, after which the door can be opened, and the wood taken out.

[0080] The process/method according to embodiments of the invention are technically less complicated and commercially less costly for producing esterification-based type of products for heavy duty applications, compared to the traditional approaches mentioned above.

[0081] Although the present invention has been disclosed in the form of embodiments and variations thereon, it will be understood that numerous additional modifications and variations could be made thereto without departing from the scope of the invention.

[0082] For the sake of clarity, it is to be understood that the use of a or an throughout this application does not exclude a plurality, and comprising does not exclude other steps or elements. The mention of a unit or a module does not preclude the use of more than one unit or module.