JPH04259502A - Manufacture of modified wood - Google Patents

Abstract

PURPOSE:To obtain modified to which stability and nonflammability are given, by only drying the wood after infiltration of a treatment solution into the wood. CONSTITUTION:A solution generating an inflammable inorganic matter which is insoluble in water by evaporating a solvent is infiltrated into raw material wood which is going to be modified up to the inside of its texture and then the wood is dried, through which the foregoing mineral is infiltrated into the wood and fixed.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a method for producing modified wood used as housing equipment, building materials, etc.

0002

[Prior art] As a method for modifying wood, it is possible to make the wood flame retardant (fire retardant) by incorporating insoluble and nonflammable inorganic substances into the wood.
Research and development are being conducted on methods for imparting properties such as dimensional stability, antiseptic and insect repellent properties, mechanical strength, and surface hardness. In general, modification methods for imparting flame retardancy to wood are broadly classified based on the following flame retardant mechanisms.

(a) Coating with inorganic substances (b) Promotion of carbonization (c) Inhibition of chain reaction in flaming combustion (d) Generation of nonflammable gas (e) Absorption of heat by decomposition and release of crystal water (f) Heat insulation by foam layer Here, as explained below, the modification method of including insoluble non-combustible inorganic substances in wood includes (b), (c), and (d) in addition to (a) above, depending on the type of inorganic substance. )
This is an excellent method that can also be expected to have effects such as Furthermore, once the insoluble, nonflammable inorganic substance is fixed in the wood structure, there is little risk of it leaching out of the wood, so there is little worry that the above-mentioned effects will be diminished.

[0004] The flame retardant mechanisms described in (a) to (d) above will be explained in detail below. The inorganic coating (a) means that even if the material is flammable, it can be made flame retardant by combining it with a nonflammable inorganic material in an appropriate mixing ratio. For example, the conventionally known wood chip cement board is made by mixing combustible wood with non-combustible cement at a weight ratio of about 3:1 to 1:1 and forming it into a board shape, which is compliant with JIS standards. Recognized as a noncombustible material.

[0005] The mechanism for promoting carbonization in (b) is as follows. When wood is heated, it decomposes and generates flammable gas, which ignites and burns.
The presence of phosphoric acid or boric acid promotes thermal decomposition, or carbonization, of wood, and a carbonized layer is quickly formed. This carbonized layer acts as a heat insulating layer and produces a flame retardant effect. Therefore, when the insoluble nonflammable inorganic substance contains a phosphoric acid component or a boric acid component, the flame retardant effect becomes even higher.

The inhibition of the chain reaction in flaming combustion (c) is contributed by halogen, and as a result of the halogen acting as a chain transfer agent in the radical oxidation reaction in the flame, the oxidation reaction The mechanism is that the flame retardant effect is produced by inhibiting the Therefore, if the insoluble nonflammable inorganic substance contains a halogen, a flame retardant effect can also be obtained by this mechanism.

The generation of nonflammable gas (d) has the following mechanism. In other words, the mechanism is that compounds such as carbonates and ammonium salts generate nonflammable gases such as carbon dioxide, sulfur dioxide, and hydrogen halides through thermal decomposition, and these gases dilute flammable gases and prevent combustion. It is. Therefore, if the insoluble nonflammable inorganic substance contains something that can generate nonflammable gas, such as carbonate, a flame retardant effect due to this mechanism can also be obtained.

[0008] Next, the preservation and insect repellency of wood will be explained. When fungi cause wood to rot, it is essential that hyphae first invade the inner cavity of the wood. However, if there are foreign substances in the wood lumen, mycelia cannot invade, so wood
As a result, it becomes less susceptible to corruption. The foreign matter in the wood lumen need not be a preservative (preservative), and may be anything as long as it does not provide nutrients for fungi. The same applies to insect repellent as preservative. Therefore, if an insoluble, noncombustible inorganic substance is included in the inner cavity of wood, the antiseptic and insect repellent properties of wood can be improved. However, the above-mentioned foreign substances are suitable as long as they have a medicinal effect; for example, it is preferable that they are poorly digestible, indigestible, or have a repellent effect on insects.

Further, dimensional stabilization and mechanical strengthening of wood will be explained. If wood can be swollen with water and some substance can be fixed in the wood cell walls, dimensional stabilization and mechanical strengthening effects can be obtained due to the bulk effect. In other words, if the inside of the wood cell wall is occupied by the filler, the wood itself is less likely to expand or contract, and at the same time, various mechanical strengths are improved. Here, as the immobilizing substance, inorganic substances that are difficult to dissolve in water can also be used. Therefore, fixing insoluble, noncombustible minerals into wood cell walls can improve dimensional stability and mechanical strength.

Finally, to explain how to improve the hardness (surface hardness) of wood, generally speaking, in order to increase the hardness of wood, hard substances such as inorganic substances are packed into the voids such as conduits inside the wood and into the cell walls of the wood. By fixing insoluble, non-combustible inorganic substances in wood, the effects of reinforcing wood cells and increasing hardness can be obtained. In this case, it is more effective to generate inorganic substances intensively on the surface layer of the wood.

As described above, the method of incorporating insoluble and nonflammable inorganic substances is very effective in modifying wood, including making it flame retardant, but it has conventionally had the following problems. . In general, even if an insoluble, nonflammable inorganic substance is directly dispersed in a solvent such as water, and wood is immersed in a treatment liquid made of this dispersion to allow the treatment liquid to penetrate into the wood, only a small percentage of the treatment liquid penetrates into the wood. Only a solvent such as water is left. This is due to the following reasons. In other words, the narrowest part of the path through which the treatment liquid passes when penetrating into the wood is the pit membrane, where the pore diameter is approximately 0.1 μm, whereas This is because the particles are usually much larger than 0.1 μm.

[0012] Therefore, a method has been developed that can solve this problem. That is, two types of aqueous solutions separately containing cations and anions that react with each other to produce insoluble nonflammable inorganic substances when mixed (hereinafter referred to as "cation-containing treatment liquid" and "anion-containing treatment liquid" in this order). is prepared by dissolving a water-soluble inorganic substance in water, and both aqueous solutions are impregnated into raw material wood in order, and the above-mentioned both ions are reacted in the wood, thereby producing an insoluble non-flammable inorganic substance. This is the manufacturing method of
(See Publication No. 246003, etc.).

According to this method, the insoluble, nonflammable inorganic substance is not impregnated as solid particles, but in the form of ions dissolved in a medium such as water, so impregnation is easy, and extremely large amounts can be impregnated. Insoluble, nonflammable inorganic substances can be efficiently incorporated into wood. Therefore, preservatives and
Modified wood with extremely excellent insect repellency and dimensional stability can be obtained.

[0014]

[Problems to be Solved by the Invention] In the above-mentioned treatment method, in order to generate a water-insoluble and non-flammable inorganic substance in wood, a cation-containing treatment liquid and an anion-containing treatment liquid constituting the inorganic substance are alternately treated at two times. The treatment process was complicated because it had to be impregnated into the wood multiple times and a chemical reaction took place in the wood.

The present invention was made in view of the above circumstances, and involves impregnating modified wood with antiseptic and insect repellent properties, dimensional stability, and flame retardancy with a treatment solution and then drying it. The object of the present invention is to provide a method for producing modified wood that can be obtained only by

[0016]

[Means for Solving the Problems] In order to solve the above-mentioned problems, the method for producing modified wood according to the present invention provides water-insoluble and non-flammable wood for the raw material wood to be modified by volatilizing a solvent. The method is characterized in that the inorganic substance is impregnated and fixed in the wood by impregnating the tissue of the wood with a solution that generates the inorganic substance, and then drying the wood.

[0017] The raw material wood for modification used in the present invention is not particularly limited, and raw wood logs and sawn timber products are exemplified. There are no limitations on the tree species, etc. In this invention, the water-insoluble and non-flammable inorganic substance that is generated and fixed in the wood tissue is not particularly limited, but examples thereof include phosphates, carbonates, sulfates, etc. . Among these salts, specific examples of phosphates include BaHPO4
, Zn3(PO4)2, Cu3(PO4)2, etc., and these may coexist in the wood. These salts are dissolved in a solvent that volatilizes with heat, such as alcoholic water or ethanol, and then impregnated into wood. The impregnation method, impregnation time, etc. are not particularly limited, and impregnation may be carried out under reduced pressure or by coating. After impregnation, the wood is dried to evaporate the solvent, thereby obtaining modified wood impregnated with and fixed with a water-insoluble and nonflammable inorganic substance. Since the obtained wood has inorganic substances impregnated and fixed inside the wood, the wood texture is not lost, and the wood has excellent appearance as well as the above-mentioned performance.

[0018]

[Operation] In the modification method according to the present invention, water-insoluble and nonflammable inorganic substances can be impregnated and fixed in the wood by simply impregnating the wood with a treatment liquid and then drying the wood. , it is possible to impart the above-mentioned performance to wood.

[0019]

[Examples] Specific examples and comparative examples of the present invention are shown below, but the present invention is not limited to the following examples. - Example 1 - A 3 mm thick rotary veneer made of lauan material was boiled in hot water at 80°C to saturate it with water. The obtained wood was immersed in the treatment solution shown in Table 1, then washed with water and dried to obtain a modified wood. Table 1 shows the impregnation rate of inorganic substances into the veneer.

-Examples 2 to 5- In the same manner as in Example 1, wood was immersed in the treatment solution shown in Table 1, washed with water, and dried to obtain modified wood. The impregnation rate of inorganic substances is also shown in Table 1.

[0021]

[Table 1]

[0022]

Effects of the Invention According to the method for producing modified wood according to the present invention, a water-insoluble and nonflammable inorganic substance is impregnated and fixed into the wood by immersing the wood in the inorganic substance-containing treatment solution and then drying it. It has excellent antiseptic and insect repellent properties, dimensional stability,
It becomes possible to impart flame retardancy to wood.

Claims (3)

[Claims] [Claim 1] The raw material wood to be modified is impregnated into its structure with a solution that produces a water-insoluble and non-flammable inorganic substance by volatilizing the solvent, and then the wood is dried. A method for producing modified wood, characterized by impregnating and fixing the inorganic substance into the wood. 2. The method for producing modified wood according to claim 1, wherein a solvent that easily evaporates by heat is used as the solvent. 3. At least one of alkali metal phosphates, carbonates, and sulfates, and alkaline earth metal phosphates, carbonates, and sulfates is used as a solute component in the solution. 2. The method for producing modified wood according to 2.