JPH04185302A - Manufacture of modified wood - Google Patents

Abstract

PURPOSE:To enable reuse of a wood modifier which is not infiltrated into wood and prevent generation of a warp in case of modification of thick and blocklike wood, by a method wherein after the modifier is infiltrated into the wood, the wood modification reaction of the modifier infiltrated wood is allowed to perform under heating and pressurization by making use of a flat plate press. CONSTITUTION:After completion of an infiltrating process infiltrating an acetylization reactive solution into wood, acetylization reaction is performed by performing pressurization and heating by a flat plate press. Then heating and extraction treatment by hot water and acetone is performed partly for removal of a wood extracted component and unreacted acetylating agent and heat drying treatment is performed. With this construction, since the infiltrating process and heat reaction process of a modifier are performed separately from each other and the modifier which is not infiltrated into the wood is not influenced at all by heat at a heating and rective process, the modifier can be reused over and over gain. Then even in the case where modification of the wood having volume to some extent is performed, since the modification reaction is allowed to perform under pressing, neither a warp nor twisting are generated. Reactor vessel can be miniaturized further.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a method for producing modified wood, and more particularly to a method for producing modified wood that can improve the dimensional stability, antiseptic properties, anti-termite properties, etc. of wood.

[Prior art]

Conventionally, it has been known to use an acetylating agent as a main modifier for wood number IIFI. In this method for producing modified wood, a pressure-resistant container that can be heated and pressurized is used to first impregnate the wood with a wood modifier under reduced pressure or pressure, and then to modify the wood by heating. A common method is to carry out a reaction. Although this method has the feature that wood processing can be carried out from start to finish in the same container, it has the following drawbacks.

[Problem to be solved by the invention]

The first of the above drawbacks is that the remaining modifier that is not impregnated inside the wood is also heated in the pressurized container in the same way as the wood, so the main modifier that is not impregnated inside the wood and does not contribute to wood modification. As a side reaction occurs, the unused modifier may become colored and impair the reuse of the modifier, and if you replenish the used modifier and repeat the modification of the wood, Since the performance of the modified wood deteriorates, there is a limit to the reuse of the modified material that has been put into the reaction system, and this inconvenience is especially noticeable when a catalyst or reaction initiator is used together.Secondly, When using thick block-shaped wood, it is easy to warp due to stress caused by swelling of wood cells during the modification reaction, which can easily cause handling problems in the post-processing process.Thirdly, pressurized containers As the volume of the reaction mixture increases, it becomes difficult to control the pressure and temperature during the reaction process. As a result of intensive studies to solve the above-mentioned problems, the present inventors discovered that good results could be obtained by performing the impregnation step and the reaction step of the wood modifier separately. Reached. Therefore, a first object of the present invention is to provide a method for producing modified wood that allows reuse of wood modifiers that are not impregnated into wood. A second object of the present invention is to provide a method for producing modified wood that is less likely to warp even when thick block-shaped wood is modified. A third object of the present invention is to provide a method for producing modified wood that can reduce the volume of the reaction vessel. Furthermore, a fourth object of the present invention is to provide a method for producing modified wood that is suitable especially when an acetylating agent is used as a modifier.

[Means to solve the problem]

The above aspects of the present invention are characterized in that in the method for producing modified wood in which wood and a wood modifier are reacted, after impregnating the wood with the modifier, the wood impregnated with the modifier is heated and pressurized. This was achieved by a method for producing modified wood that carries out a wood modification reaction. The present invention will be explained in detail below. The wood used in the present invention is not particularly limited,
For example, it can be applied to agathis wood. The wood modifier used in the present invention can be appropriately selected from publicly known ones, but in particular, from the viewpoint of improving the dimensional stability of wood as well as its antiseptic properties and anti-termite properties, acetylated wood modifiers can be used. It is preferred to use agents. Examples of the acetylating agent include acetic anhydride, ketene, and acetic acid chloride. When carrying out acetylation using the above-mentioned modifiers, a basic substance is usually used as a catalyst. When carrying out a wood modification reaction, in order to quickly impregnate the wood with the modifier, at least one compound selected from amine-based or amide-based compounds whose swelling coefficient for wood is larger than that of water is added. It is preferable to use them together in order to impregnate the wood with the modifier. In particular, since these compounds are basic, they not only function as swelling agents for the wood, but also can be used as modifiers. This is a particularly preferred embodiment of the present invention, since it also functions as a reaction catalyst between the hydroxyl groups in the wood and the acetylating agent. Examples of amine or amide compounds that can be used in the present invention include n-butylamine, piperidine,
Examples include pyridine and dimethylamide. The mixing ratio of the amine or amide compound to the acetylating agent is used in the range of 70/30 to 9515 by volume. The treatment of wood with an acetylation reaction solution consisting of these acetylating agents and amine-based or amide-based compounds can be carried out by a reduced pressure/pressure method that includes a reduced pressure step and a pressurized step.
Usually, it is sufficient to select a degree of pressure reduction of 10 Torr or less, a degree of pressure of 5 to 10 kg/cd, and a reaction time of about 1 hour in both the pressure reduction and pressurization steps. In the present invention, after completing the impregnation step of impregnating wood with an acetylation reaction solution, the acetylation reaction is carried out by applying pressure and heating using a flat plate press (hereinafter referred to as the flat plate press method). The excess acetylation reaction solution that is not impregnated into the wood is removed and recovered and used again for the reaction. The temperature of the acetylation reaction using the flat plate press method is 120°C.
~130°C1 pressure is 5kg/Ci ~10kg/Cr1
The reaction time is 5 minutes to 30 minutes. When the heating temperature exceeds 130°C, the bonds of lignin, which is a wood component, begin to loosen, and as the temperature rises, the bonds between each wood component begin to decompose, resulting in a significant decrease in the strength of the wood and the occurrence of cracks. Temperatures below 120°C are not preferred because the reaction takes a long time. The pressure during flat plate pressing is particularly between 8 kg/d and 10 kg/c in order to enhance the effect of modification without degrading the wood.
ill is preferred. The pressurizing time by the flat plate press method varies depending on the type of wood, but - for boat fishing, it is preferably about 30 minutes to 120 minutes. For example, for agathis wood, the time is about 5 to 30 minutes, and for cypress wood, about 120 minutes is sufficient. After the acetylation reaction is completed, a heat extraction process using hot water and acetone is performed to remove wood extract components and unreacted acetylating agent, and then a heat drying process is performed.

【Effect of the invention】

As detailed above, according to the wood modification method of the present invention, the modifier impregnation step and heating reaction step are carried out separately, so that the modifier that is not impregnated into the wood is exposed to heat in the heating reaction step. It can be reused as many times as it is unaffected by this. In addition, even when modifying not only veneer or board materials but also wood with a certain volume, the modification reaction is carried out under a press, so it is not affected by the swelling stress of wood cells as in conventional methods. There is no chance that warping or twisting will occur during the reforming reaction. Furthermore, it is also possible to downsize the container used when impregnating wood with the modifying material.

【Example】

EXAMPLES The present invention will be explained in more detail with reference to Examples below, but the present invention is not limited thereto. Example 1 Agathis square block material and Cypress square block material subjected to acetone and hot water extraction were immersed in an acetyl flower material solution consisting of 70 parts by weight of acetic anhydride and 30 parts by weight of pyridine,
Under reduced pressure (vacuum degree 10Torr) and under pressure (8,5k
The impregnation treatment of acetylated rhizomes was carried out for 60 minutes at (g/ctA), respectively. Next, after removing the acetylating agent, the wood impregnated with acetyl and other agents was heated and pressurized (temperature 120°C, pressure 8.5 kg/cIT) using a flat plate press method.
Perform the acetylation reaction for 0 minutes, then extract with hot water and acetone (
After drying with air for 8 hours each time at a temperature of 80"C, acetylated wood was obtained. Comparative Example 1゜Instead of the flat plate pressing method used in Example I, an impregnating treatment was used. Example 1 except that the autoclave was used as it was.
After carrying out the acetylation reaction under the same conditions as above, air drying was performed to obtain acetylated wood. Weight increase rate (WPC), bulking rate, water absorption increase rate (RWA) of the acetylated wood obtained in Example 1 and Comparative Example 1
) and anti-swelling ability (ASE) were measured and the results shown in Table 1 were obtained. In addition, each measurement value was calculated by the following calculation formula. ■Weight increase rate (WPG): Bulky-dry weight of wood before treatment x 100 (%), Bulking rate: Bulky-dry dimension of wood after treatment - Bone-dry dimension of wood before treatment Bound-dry dimension of wood before treatment x 100 (%) ■Water absorption increase rate (RWA): Water absorption rate of untreated wood - Water absorption rate of treated wood Water absorption rate of untreated wood After immersion in [temperature 23°C and 24 hour lateral measurement] ■ Dimensional stability (ASE): Dimensional change rate of untreated wood - Dimensional change rate of treated wood Dimensional change rate of untreated wood X 100 (%) As is clear from the results in Table 1, although there are differences in reactivity depending on the type of wood, the modified wood obtained by the present invention has a weight gain rate (WPG) and dimensional stability comparable to that of the autoflave method for agathis wood. I got sex.

Claims (1)

[Claims] 1) In a method for producing modified wood in which wood and a wood modifier are reacted, after the wood is impregnated with the modifier, the modifier-containing wood is processed using a flat plate press. A method for producing modified wood, characterized by carrying out a wood modification reaction under pressure and heat. 2) The method for producing modified wood according to claim 1, wherein the modifier is an acetylating agent.