JPH0322801B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for modifying wood materials.

(Prior art) Wood and its processed materials, such as wood veneers and wood chips, are light and strong, and have unique physical properties and textures, so they are used for a wide range of purposes such as construction materials and furniture materials. ing.

However, this wood is not only susceptible to erosion by various fungi and insect damage such as termites, but also prone to rot.
Due to its breathability, it has the disadvantage of being susceptible to deformations such as warping, twisting, and expansion/contraction.

Therefore, in recent years, attempts have been made to acetylate wood materials in order to eliminate the above-mentioned drawbacks.

In other words, acetylated wood was obtained by immersing wood in an acetylation reaction solution, then removing the wood from the reaction solution, washing and drying the wood, but the reaction time was long and the process was very slow. productivity is poor.

In this acetylation reaction, in order to shorten the reaction time and increase productivity, the reaction is carried out in a high temperature reaction solution of 100°C or higher, but such treatment extracts wood components into the reaction solution and This causes defects such as discoloration and deterioration of the material. For this reason, it is necessary to shorten the immersion time of the wood material in the reaction solution.
In this case, a disadvantage arises that the acetylation rate is low.

(Problems to be Solved by the Invention) Therefore, the present invention provides a modification treatment for wood that can achieve a high degree of acetylation without prolonging the immersion time of the wood in a high-temperature reaction solution. We are here to provide you with a method.

(Means for Solving the Problems) The present invention uses a pre-heated reaction solution to be injected into the reaction container, and even after the reaction solution is extracted, high temperature unreacted water remains in the wood. Focusing on the fact that the reaction solution is sufficiently contained and the wood material is also at a high temperature, we immersed the wood material in the acetylation reaction solution and heated it to acetylate the hydroxyl groups of the wood components. After the reaction liquid reaches a predetermined temperature, the reaction liquid that has not been impregnated into the wood material is collected from the reaction vessel, and then, while maintaining the temperature of the wood material, the reaction liquid that has been impregnated into the wood material is poured into the reaction liquid. Therefore, this is a method for modifying wood materials that further promotes acetylation.

(Function/Effect) As described above, in the present invention, the reaction solution is heated in advance to a state where the acetylation reaction can be carried out, and furthermore, after the reaction solution is collected, the temperature of the wood material is maintained. If necessary, the container is heated as appropriate and the acetylation proceeds with the reaction liquid in the wood, so there is no extraction of wood components and a high degree of acetylation is achieved without causing discoloration or deterioration of the wood. be able to.

(Example) Hereinafter, a method for modifying wood materials according to the present invention will be described.

The wood materials to which the present invention is applied include wood, wood veneers, wood chips, etc. If the wood material is 3 mm or more thick, it may be necessary to apply a catalyst treatment in advance to promote the acetylation reaction described below. is preferred.

In this case, the catalyst used is sodium acetate, potassium acetate, etc., which do not deteriorate the wood material.
In addition, acetate aqueous solutions that can be easily removed by washing with water are preferable, and the acetate salt can be simply immersed in these aqueous solutions, heated to 40° to 80°C for rapid impregnation, or heated in a vacuum pressure cooker. The aqueous solution may be impregnated by injection under reduced pressure, injection under increased pressure, or injection under reduced pressure.

Note that the concentration of the acetate aqueous solution is not particularly limited, but is preferably 2 to 30%.

Next, the wood material impregnated with the acetate aqueous solution is appropriately dried, but it is preferable that the water content of the wood material is 10% or less.

The catalyst-containing wood material or untreated wood material dried as described above is immersed in a high temperature (approximately 100°C) acetylation reaction solution placed in a reaction vessel,
By heating the solution to maintain its temperature, the hydroxyl groups of the wood components react with the reaction solution, thereby acetylating the wood.

The reaction solution is mainly composed of acetic anhydride, in which less than 30% of acetic acid or aromatic hydrocarbons such as toluene, xylene, and benzene may be used.

In this way, mixing an organic solvent into acetic anhydride reduces the amount of unnecessarily expensive acetic anhydride used, reduces the strong pungent odor of acetic anhydride, and improves the working environment. This is to reduce the decrease in strength of wood materials caused by acetic acid.

Furthermore, before immersing the wood material in the reaction solution, it is desirable to vacuum the wood material under reduced pressure in advance to remove air from the wood material before immersing it in the reaction solution.

Note that the wood material may be simply immersed in the reaction solution, but it is also possible to inject the reaction solution into the wood material in advance using a vacuum method, pressurization method, or vacuum pressure method in a vacuum pressure cooker (reaction container). Good too.

Then, the reaction solution in the reaction vessel was heated to 120%
Once the temperature reaches 120°C, the reaction liquid that is not impregnated into the wood material is collected from the reaction vessel, and then the reaction vessel is heated to maintain the reaction liquid-impregnated wood material at 120°C, while
Acetylation proceeds with the impregnation reaction solution.

After a predetermined period of time has elapsed, the wood material is taken out from the reaction vessel, washed with warm water, etc., and dried to obtain the desired acetylated wood material.

Experimental example: 12% by weight on 3mm thick larch rotary veneer
The veneer was impregnated with an aqueous acetate catalyst solution and dried, and the veneer was placed in a reaction vessel, which was a reaction vessel, and heated to 40 mmHg.
After deaerating the inside of the pot under reduced pressure for 5 minutes, a reaction solution consisting of 95% by weight of acetic anhydride and 5% by weight of acetic acid was poured into the pot under reduced pressure, and the reaction solution was poured into the veneer for 10 minutes. Injected. Next, after releasing the reduced pressure state and once deliquifying the reaction solution, the same reaction solution heated to 100°C was poured into the pot, and nitrogen gas was supplied into the pot to keep the pressure inside the pot at 8 kg/cm for 30 minutes. ² , and the reaction solution was injected under pressure into the veneer, during which time the reaction solution was raised to 120°C. Then, the pressurized state is released to drain the reaction solution, and then the reaction vessel is heated and maintained at 120°C.
The acetylation reaction was allowed to proceed for 30 minutes, and the resulting veneer was washed and dried, and the acetylation rate was measured and found to be 18%.

Comparative Example Acetylation was carried out under the same conditions and procedures as in the previous example, without using a heated reaction solution, and at the same time as the reaction solution was removed, the veneer was washed, dried, and the veneer was dried. When the acetylation rate was measured, it was 10%.
It was hot.

As described above, in the present invention, the acetylation reaction is carried out using the reaction liquid impregnated into the wood material, and the amount of reaction liquid used is minimized.
It prevents discoloration and deterioration of the wood due to the outflow of wood components from acetylated wood, reduces the time required to heat up the reactor by injecting the heated reaction liquid, and reduces costs by increasing the number of times the reactor is used due to the shortened reaction time. This is intended to bring down the situation.

Claims (1)

[Scope of Claims] 1 A wooden material is immersed in a heated acetylation reaction solution, and while the hydroxyl groups of the wood component are acetylated while being further heated, after the reaction solution reaches a predetermined temperature, The method is characterized in that the reaction solution that has not been impregnated into the wood material is recovered from the reaction vessel, and then acetylation is further progressed with the reaction solution that has been impregnated into the wood material while maintaining the temperature of the wood material. A method for modifying wood materials. 2. The method for modifying wood materials according to claim 1, wherein the reaction liquid is a mixture of acetic anhydride and an organic solvent such as an aromatic hydrocarbon. 3. The method for modifying a wood material according to claim 1, wherein the wood material is impregnated with an aqueous acetate catalyst solution and then dried.