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. A method of treating wood or engineered wood, comprising: step 1, step 2, and step 3, wherein step 1 includes either substeps 1a) through 1c) or substeps 1aa) through 1dd), wherein substeps 1a) through 1c) include: 1a) selecting and placing the wood or engineered wood in hydrolysis chamber that can be heated, cooled, and pressurized; 1b) applying a vacuum to the hydrolysis chamber in order to empty cells of the wood or engineered wood; and 1c) providing an aqueous impregnation solution comprising an impregnation agent suitable for esterification in the hydrolysis chamber, pressurizing the hydrolysis chamber, and heating the hydrolysis chamber sufficiently to evaporate the aqueous impregnation solution, wherein the evaporated aqueous impregnation solution penetrates the cells of the wood or engineered wood and impregnates the wood or engineered wood; and wherein substeps 1aa) through 1dd) include: 1aa) selecting and placing the wood or engineered wood in a vacuum/pressure chamber; 1bb) providing an aqueous impregnation solution comprising an impregnation agent suitable for esterification and pressuring the vacuum/pressure chamber, wherein the aqueous impregnation solution impregnates the wood or engineered wood by either full cell impregnation or empty cell impregnation; 1cc) transferring the impregnated wood or engineered wood to the hydrolysis chamber; and 1dd) pressurizing and heating the hydrolysis chamber containing the impregnated wood or engineered wood; wherein step 2 includes maintaining pressure and heat in the hydrolysis chamber for a holding phase, wherein during the holding phase hemicelluloses of the impregnated wood or engineered wood are hydrolyzed to produce carboxylic acids, while simultaneously, the impregnation agent suitable for esterification in the impregnated wood or engineered reacts with the produced carboxylic acids, resulting in polymerization of the impregnation agent suitable for esterification to form a polymerized wood or engineered wood product; and wherein step 3 includes lowering the temperature to ambient temperature and lowering the pressure in the hydrolysis chamber to atmospheric pressure; wherein the method does not include a drying step wherein the impregnated wood or engineered wood is dried to a level allowing thermal modification between impregnation and hydrolysis during the holding phase.

2. The method according to claim 1, wherein the wood or engineered wood is spruce, fir, pine, beech, oak, birch, and/or ash.

3. The method according to claim 1, wherein the impregnation agent suitable for esterification is selected from sorbitol, glycerol, furfuryl alcohol, or xylitol.

4. The method according to claim 1, wherein the impregnation agent suitable for esterification is dimethylol ethyleneurea.

5. The method according to claim 1, wherein the general chemical process for hydrolysis of hemicelluloses of the impregnated wood or engineered wood to produce carboxylic acids and simultaneous reaction of the impregnation agent suitable for esterification in the impregnated wood or engineered wood with the produced carboxylic acids is: $\begin{array}{cc}\left(C_5{H}_{10}{O}_5\right)\underset{H_{2}O}{.Math.}{C}_5{H}_{10}{O}_5\underset{{\mathrm{RCO}}_{2}H}{.fwdarw.}{R\mathrm{CO}}_{2}H+R^{}\mathrm{OH}.Math.{R\mathrm{CO}}_{2}H{R}^{}+H_{2}O\underset{\mathrm{Polymerisation}}{.fwdarw.}\mathrm{Polyesters}.& \left(3\right)\end{array}$

6. The method according to claim 1, wherein the pressure during the holding phase is between 5 and 20 Bar (A).

7. A wood treated according to the method according to claim 1.

8. The method according to claim 1, wherein impregnation comprises a pressure phase with a pressure of 15 Bar (a).

9. A method of creating a polymerized wood or engineered wood product, comprising: providing wood or engineered wood; impregnating the wood or engineered wood with an impregnation agent to form an impregnated wood or engineered wood, wherein the impregnation agent is suitable for esterification; providing the impregnated wood or engineered wood in a hydrolysis chamber; pressurizing the hydrolysis chamber to between 5 and 20 Bar (A) and heating the hydrolysis chamber to between 10 and 175 C. for between 30 minutes and 12 hours, during which hemicelluloses of the impregnated wood or engineered wood are hydrolyzed to produce carboxylic acids, while substantially simultaneously, the impregnation agent in the impregnated wood or engineered reacts with the produced carboxylic acids, resulting in polymerization of the impregnation agent suitable for esterification to form the polymerized wood or engineered wood product.

10. The method of claim 9, wherein the method does not include a drying step wherein the impregnated wood or engineered wood is dried to a level allowing thermal modification between impregnation and hydrolysis.

11. The method of claim 9, wherein impregnating the wood or engineered wood occurs in the hydrolysis chamber.

12. The method of claim 9, wherein impregnating the wood or engineered wood occurs in a separate chamber.

13. The method of claim 9, wherein the impregnation agent comprises furfuryl alcohol.

14. The method of claim 9, wherein impregnating the wood or engineered wood comprises providing the wood or engineered wood in a vacuum/pressure chamber, pressurizing the vacuum/pressure chamber, providing an impregnation solution comprising the impregnation agent in the vacuum/pressure chamber, further pressurizing the vacuum/pressure chamber and maintaining the vacuum/pressure chamber in a further pressurized state, removing any excess impregnation solution, and applying a vacuum to the vacuum/pressure chamber.

15. The method of claim 9, wherein impregnating the wood or engineered wood comprises providing the wood or engineered wood in a vacuum/pressure chamber, applying a first vacuum to the vacuum/pressure chamber, providing an impregnation solution comprising the impregnation agent in the vacuum/pressure chamber, pressurizing the vacuum/pressure chamber and maintaining the vacuum/pressure chamber in a pressurized state, removing any excess impregnation solution, and applying a second vacuum to the vacuum/pressure chamber.

16. The method of claim 9, wherein the wood or engineered wood is spruce, fir, pine, beech, oak, birch, and/or ash.

17. The method of claim 9, wherein the impregnation agent suitable for esterification is selected from sorbitol, glycerol, furfuryl alcohol, or xylitol.

18. The method of claim 9, wherein the impregnation agent suitable for esterification is dimethylol ethyleneurea.

19. The method of claim 9, wherein the general chemical process for the hydrolysis of hemicelluloses of the impregnated wood or engineered wood to produce carboxylic acids and simultaneous reaction of the impregnation agent in the impregnated wood or engineered wood with the produced carboxylic acids is: $\begin{array}{cc}{\left(C_5{H}_{10}{O}_5\right)}_n\underset{H_{2}O}{.Math.}{C}_5{H}_{10}{O}_5\underset{{\mathrm{RCO}}_{2}H}{.fwdarw.}{R\mathrm{CO}}_{2}H+R^{}\mathrm{OH}.Math.{R\mathrm{CO}}_2{HR}^{}+H_{2}O\underset{\mathrm{Polymerization}}{.fwdarw.}\mathrm{Polyesters}.& \left(3\right)\end{array}$

Description

AN EXAMPLE OF A COMBINED HYDROLYSIS AND FURFURYLAZATION PROCESS

(1) This process can be done in different ways. In particular, it can be done in either a one step or a two-step process.

(2) 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.

(3) 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.

(4) One step process.

(5) 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.

(6) 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.

(7) Third, the chamber is pressurized to 15 Bar(A)

(8) 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.

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

(10) 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.

(11) 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.

(12) Fifth, the chamber is cooled down to ambient temperature, and

(13) 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.

(14) Two-Step Process

(15) First StepImpregnation

(16) 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.

(17) The impregnation process can be in two different ways:

(18) 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.

(19) First, pressure in the chamber is elevated to 5 bar(A).

(20) Second, the chamber is filled with the FA solution.

(21) Third, pressure in the chamber is elevated to 15 bar(A).

(22) Fourth, the pressure is kept for 2 hours, or until full uptake of the FA fluid is achieved.

(23) Fifth, the chamber is emptied for FA fluid.

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

(25) 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.

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

(27) Second, the chamber is filled with the FA solution.

(28) Third, the pressure in the chamber is elevated to 15 Bar(A).

(29) Fourth, the pressure is kept for 2 hours, or until full uptake of the FA fluid is achieved.

(30) Fifth, the chamber is emptied for FA fluid.

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

(32) Second StepHydrolysis and Polymerization

(33) 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.

(34) Second, the pressure in the chamber is elevated to 15 Bar(A).

(35) Third, the temperature is elevated to 150 deg. C.

(36) Steps two and three can be combined in one step.

(37) 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.

(38) 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.

(39) Fifth, the temperature in the chamber is brought down to ambient temperature, and

(40) Sixth, the pressure in the chamber is brought down to atmospheric pressure, after which the door can be opened, and the wood taken out.

(41) 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.

(42) 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.

(43) 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.