JP4872059B2 - Method for producing wood material having humidity control and dimensional stability and wood material - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a wood material having both humidity control and dimensional stability and the wood material.
[0002]
[Prior art]
Wood materials such as solid wood and wood boards are hygroscopic materials that absorb or desorb moisture until they are in equilibrium with the surrounding humidity. And moisture absorption / release at a moisture content below the fiber saturation point causes shrinkage and swelling of the wood. The shrinkage and swelling of the wood material cause various obstacles in the processing and use of the wood material, such as dimensional deviation and cracking due to drying and humidity change. Therefore, when using a wooden material as a building material, it is necessary to reduce the shrinkage / swelling of the wooden material and to impart high dimensional stability.
[0003]
The conventional dimensional stabilization treatment is a method of causing cross-linking in the hydrophilic hydroxyl group present in the cell wall of the wood material that bears strength and shape (crosslinking treatment: formalization), and the hydroxyl group with a hydrophobic group Treatments such as a substitution method (hydrophobization: acetylation) or a method of filling a wood material with a bulking agent (bulking structure) are generally performed.
[0004]
[Problems to be solved by the invention]
However, all of the conventional dimensional stabilization treatments form a mechanism that inhibits the adsorption of water inside the wooden material, and while the wooden material is given dimensional stability, the wooden material originally has it. It is detrimental to the advantage of moisture absorption and desorption. Current houses are becoming highly insulated and highly airtight, and if wood materials such as the above, which have poor moisture absorption and release properties, are used as building materials, there is a risk that the living space will become a temperate humidity environment such as high humidity or overdrying. is there. High humidity may cause allergies due to mold and mite breeding, and overdrying (low humidity) tends to cause damage due to drying of mucous membranes such as nose and throat. For this reason, at present, indoor humidity is being maintained within a certain range using auxiliary equipment such as a humidifier and a dryer.
[0005]
This invention is made | formed in view of said situation, The objective is to provide the wooden material which has required dimensional stability, and its manufacturing method, maintaining moisture absorption / release property. By using the wood material obtained by the present invention as a building material, it is possible to obtain and maintain a comfortable living space in which humidity is maintained within a predetermined range without using auxiliary equipment such as a humidifier and a dryer. It becomes easy.
[0006]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention impregnates a wooden material with an aqueous solution of a compound having at least two functional groups selected from carboxyl groups and aldehyde groups and at least one hydroxyl group, followed by heat treatment. Disclosed is a method for producing a wood material having humidity control and dimensional stability.
[0007]
In the case of the production method of the present invention, as shown in the conceptual diagram of FIG. 1, the aldehyde group (CHO) and / or the compound of the compound impregnated in the wood material between two hydroxyl groups (-O) in the cell wall. Cross-linking is formed by carboxyl groups (—COOH), thereby ensuring dimensional stabilization of the wood material. At the same time, the question of the cross-linking point (●-●) comes to introduce the hydroxyl group (-○) that the compound has in its structure. Absorbs and releases moisture.
[0008]
Therefore, it is possible to maintain a comfortable humidity environment inside the house (living space) by using the wood material according to the present invention as a building material in a highly airtight and highly heat-insulated house, and at the same time, the building material is subjected to a crosslinking treatment. Since dimensional stabilization is achieved, problems such as warping, twisting, extension, and shrinkage of the building material are also avoided. As the compound, dicarboxylic acids, tricarboxylic acids, dialdehydes, or aldehyde / carboxylic acids are preferable. Malic acid or tartaric acid is used for dicarboxylic acids, citric acid is used for tricarboxylic acids, and D- is used for aldehyde / carboxylic acids. Glucuronic acid and the like are preferable. Of these, malic acid and tartaric acid are particularly preferable from the viewpoint of moisture absorption and desorption.
[0009]
In the present invention, the wood material to be treated is not particularly limited, and has been conventionally used as a wood material such as particle board, MDF, OSB, wood, wood chip, laminated wood, or veneer. The method of the present invention can be applied to any woody material.
[0010]
【Example】
Hereinafter, the present invention will be described by way of examples.
[Example 1]
A specimen having a size of 23 mm × 23 mm × 5 mm was prepared from a sapwood portion of cypress (Chamaecyparis obtusa). Agents selected for treatment, malic acid _{(HOOC-CHOH-CH 2 -COOH} ), is tartaric acid _{(HOOC- (CHOH) 2 -COOH)} , D- glucuronic acid (OHC- (CHOH) ₄ -COOH) . A test specimen was impregnated in an aqueous solution of each drug and subjected to a reduced pressure impregnation treatment, followed by heat treatment at 170 ° C. for 2 hours, and the weight increase rate and bulking rate were examined. Next, the specimen was placed in a humidity-controlled environment at 23 ° C. and a relative humidity of 96%, and the water content and anti-swelling rate (ASE) were examined.
[0011]
FIG. 2 shows the relationship between the concentration of each aqueous solution and the weight increase rate. This relationship was proportional for any drug, with tartaric acid being the largest in proportion. FIG. 3 shows the relationship between the weight increase rate and the bulking rate. Both drugs have a bulking effect, and the tendency of malic acid and tartaric acid is almost the same, but the bulking effect of glucuronic acid is less than that. The bulking rate is calculated by the equation: (total dry volume of treated material−total dry volume of untreated material) ÷ (total dry volume of untreated material) × 100 (%).
[0012]
FIG. 4 shows the relationship between the weight increase rate and the moisture content at 23 ° C. and a relative humidity of 96%. The moisture content here is based on the weight of wood. In the case of treatment with any chemical, the water content decreases until the weight increase rate reaches about 10%, but the water content tends to increase when the weight increase rate exceeds about 10%. In particular, the increase in moisture content when treated with tartaric acid is significant.
[0013]
FIG. 5 shows the relationship between the weight increase rate and the anti-swelling rate (ASE). In the case of malic acid, a maximum of 50% ASE is obtained. In addition, when treated with malic acid or tartaric acid, ASE increased at first with the increase in weight, but ASE tended to decrease thereafter. This is considered to be related to the improvement in hygroscopicity accompanying the increase in weight due to the above-described treatment. The anti-swelling rate (ASE) is calculated by an equation of (volume swelling rate of untreated material−volume swelling rate of treated material) ÷ (volume swelling rate of untreated material) × 100 (%).
[0014]
As shown in FIGS. 3 and 5, the specimen subjected to the treatment according to the present invention has improved bulking rate and anti-swelling rate (ASE), and at the same time improved dimensional stability. As shown in Fig. 4, the equilibrium moisture content is the same as or higher than that before treatment, and a significant improvement is also achieved in terms of moisture absorption and desorption as compared with the one subjected to dimensional stabilization treatment by the conventional method. You can see that
[0015]
[Example 2]
A particle board sample (dimensions 23 mm × 23 mm × 5 mm) was impregnated with 30% by weight tartaric acid aqueous solution for 8 hours under reduced pressure, air-dried (24 hr), heat-treated at 170 ° C. for 2 hours, then 23 ° C. and relative humidity When the equilibrium moisture content (humidity control capacity) and ASE (anti-swelling rate) were measured at 96% compared to the untreated sample, the equilibrium moisture content of the treated and untreated products was 20% and 17%, respectively. The ASE of the processed product was 40%. The treated product had improved humidity control capability and improved dimensional stability compared to the untreated product.
[0016]
[Example 3]
An MDF sample (dimensions 23 mm × 23 mm × 5 mm) was impregnated with 25% by weight of D-glucuronic acid aqueous solution for 8 hours under reduced pressure, air-dried (24 hr), heat-treated at 170 ° C. for 2 hours, then 23 ° C., When the equilibrium moisture content (humidity control capacity) and ASE (anti-swelling rate) were measured at a relative humidity of 96% compared to the untreated sample, the equilibrium moisture content of the treated and untreated products was 16% and 17%, respectively. The ASE of the processed product was 40%. The treated product had almost the same humidity control ability as the untreated product, and the dimensional stability was improved.
[0017]
【Effect of the invention】
ADVANTAGE OF THE INVENTION According to this invention, the wooden material which improved moisture absorption / release property is obtained, maintaining high dimensional stability. By using the wood material according to the present invention, it becomes easy to obtain a comfortable living space in which the indoor humidity is kept within a predetermined range.
[Brief description of the drawings]
FIG. 1 is a conceptual diagram of processing in the case of a manufacturing method according to the present invention.
FIG. 2 is a graph showing the relationship between the concentration of an aqueous solution of each compound and the weight increase rate of a wood material in the case of the production method of the present invention.
FIG. 3 is a diagram showing a relationship between a weight increase rate of a wood material and a bulking rate in the case of the manufacturing method according to the present invention.
FIG. 4 is a diagram showing a relationship between a weight increase rate of a wood material and a moisture content in the case of the production method of the present invention.
FIG. 5 is a view showing a relationship among a wood material, a weight increase rate, and an anti-swelling rate (ASE) in the case of the production method of the present invention.

Claims (4)

A method for producing a wood material having humidity control and dimensional stability, wherein the wood material is impregnated with an aqueous solution of a dialdehyde or aldehyde / carboxylic acid having at least one hydroxyl group , and then heat-treated. .   The method for producing a woody material according to claim 1, wherein the aldehyde / carboxylic acid is D-glucuronic acid.   The method for producing a wood material according to claim 1 or 2, wherein the wood material is any one of a wood board such as particle board, MDF, and OSB, wood, wood chips, laminated wood, or a single plate.   A wood material having humidity control and dimensional stability produced by the production method according to claim 1.

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