JPH0519881B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field] This invention relates to a method for producing modified wood used as building materials and the like. [Background Art] A method for producing modified wood has been developed in which insoluble and noncombustible inorganic substances are generated in wood to impart dimensional stability, flame retardancy, antiseptic and insect repellent properties, and mechanical strength. Next, flame retardant wood will be explained. As a treatment method to impart flame retardancy to wood,
There are various methods. When classified based on the flame retardant mechanism, they can be roughly divided into the following types. (a) Coating with inorganic substances (b) Acceleration of carbonization (c) Inhibition of chain reaction in flaming combustion (d) Generation of nonflammable gas (e) Heat absorption due to decomposition and release of crystal water (f) Heat insulation by foam layer In wood If an insoluble, nonflammable inorganic substance is included, in addition to the above-mentioned (a), depending on the type of inorganic substance, the effects of mechanisms (b), (c), and (d) can also be expected. Furthermore, insoluble, nonflammable inorganic substances are less likely to dissolve out of the wood, so there is less risk of their effectiveness being diminished. The mechanisms of (a), (b), (c) and (d) will be explained in detail below. The inorganic coating in (a) is
Even if the material is combustible, it can be made flame retardant by combining it with a nonflammable inorganic material at an appropriate blending ratio. For example, the conventionally known wood chip cement board is made by mixing combustible wood with noncombustible cement at a weight ratio of about 1:1 and forming it into a board shape, and is recognized as a quasi-noncombustible material by JIS. It is being The mechanism for promoting carbonization in (b) is as follows. When wood is heated, it thermally decomposes and generates flammable gas, which ignites and burns, and the presence of phosphoric acid or boric acid promotes the thermal decomposition, or carbonization, of the wood. The carbonized layer thus formed 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 is high. (c) is a mechanism in which halogen acts as a chain transfer agent in a radical oxidation reaction in a flame, thereby inhibiting the oxidation reaction and producing a flame retardant effect. Therefore, if the insoluble nonflammable inorganic substance contains halogen, a flame retardant effect can be obtained by this mechanism. (d) is
The mechanism is that carbonates, ammonium salts, and the like generate nonflammable gases such as carbon dioxide, sulfur dioxide, and hydrogen halides through thermal decomposition, and these gases dilute flammable gases and thereby prevent combustion. Therefore, if the insoluble nonflammable inorganic substance can generate nonflammable gas such as carbonate, a flame retardant effect can be obtained by this mechanism. Next, we will explain how to make wood rot-proof and insect-proof. When fungi cause wood to rot, it is essential that hyphae first invade the cavities of the wood. but,
If foreign matter is present in the internal cavity of the wood, mycelium cannot enter, and as a result, it becomes difficult to rot. The foreign matter in the wood lumen does not have to be a particularly antiseptic agent (preservative), and may be anything as long as it does not serve as nutrients for fungi. The same applies to insect repellent as preservative. Therefore, if an insoluble, nonflammable inorganic substance is included in the wood cavity, the antiseptic and insect repellent properties of the wood can be improved. Additionally, dimensional stabilization and mechanical strengthening of wood will be discussed. If wood is 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. Inorganic substances that are difficult to dissolve in water can also be used as immobilizing substances. Therefore, fixing insoluble, noncombustible minerals into wood cell walls can improve dimensional stability and mechanical strength. However, in general, even if an insoluble, nonflammable inorganic substance is directly dispersed in water and a treatment liquid made of this dispersion is attempted to penetrate into wood, almost only water will penetrate into the wood. This is due to the following reasons. In other words, the narrowest part of the path that the treatment liquid must pass when penetrating into the wood is the pit membrane, where the pore diameter is approximately 0.1 μm, whereas the dispersed insoluble and nonflammable inorganic material This is because the particles are usually much larger than 0.1 μm. Therefore, the inventors created two aqueous solutions separately containing ions that can react to produce an insoluble nonflammable inorganic substance by dissolving the water-soluble inorganic substance in water, and then injecting both aqueous solutions into wood cells in turn. We have developed a method to generate insoluble, nonflammable inorganic substances by impregnating the wood with wood and causing the ions to react with each other in the wood. According to this method, regarding antiseptic and insect repellent properties,
Excellent modified wood can be obtained. However, regarding dimensional stability, mechanical strength and flame retardancy,
In recent years, higher standards have been required, and it has not been possible to obtain high standards that can meet these demands. [Object of the invention] This invention was made in view of the above circumstances, and has excellent antiseptic and insect repellent properties, and
The object of the present invention is to provide a method for producing modified wood that can efficiently produce wood with highly excellent dimensional stability, mechanical strength, and flame retardancy. [Disclosure of the Invention] The inventors have conducted extensive research in an attempt to achieve the above object by efficiently increasing the amount of insoluble, nonflammable inorganic substances contained in wood. As a result, three aqueous solutions are impregnated: two water-soluble inorganic aqueous solutions that produce an insoluble non-flammable inorganic substance when mixed, and a water-soluble inorganic aqueous solution that produces an insoluble non-flammable inorganic substance when mixed with either one of the two. They discovered that it was possible to do just that, and here they completed this invention. Therefore, this invention separately prepares three aqueous solutions: two water-soluble mineral aqueous solutions that are mixed to produce an insoluble non-flammable mineral, and one of the water-soluble mineral water solutions that is mixed with one of the two to produce an insoluble non-flammable mineral. The gist is a method for producing modified wood, which is characterized by fixing an insoluble, nonflammable inorganic substance within the wood structure by impregnating it with a wood. This invention will be explained in detail below. Examples of the wood used in this invention include raw logs, sawn timber products, sliced veneers, plywood, etc.
The type is not particularly limited. It is preferable to saturate the wood with water beforehand. The insoluble, nonflammable inorganic substances that are generated in wood and dispersed and fixed in the wood structure are not particularly limited, and include carbonates, sulfates, silicates, phosphates, borates, hydroxides, etc. Two or more types of inorganic substances may coexist in the wood. Further, one type of insoluble nonflammable inorganic substance may contain two or more types of each of the following cation moiety and/or anion moiety. As the elements constituting the cation portion of the above-mentioned inorganic compound (salt), alkali metal elements such as Na and K, alkaline earth metal elements such as Mg, Ca, Sr, and Ba, Zn and Al can be used. Preferably, but not limited to, for example,
Transition elements such as Mn, Ni, and Cd and carbon group elements such as Si and Pb can be used. The anion part is composed of BO ₃ ,
Preference is given to using PO ₄ , CO ₃ , SO ₄ and OH anions. However, it is not limited to these, and includes, for example, F, Cl, Br, I, O,
It may be NO ₃ anion or the like. BO ₃ , PO ₄
For anions, the effect is due to the flame retardant mechanism (b), and for CO ₃ anions, the effect is due to the same mechanism (d), F, Cl,
Br anions are more suitable because the effects of (c) and (d) can be expected. The cation moiety and the anion moiety may be used alone or in combination. Here, not all combinations of the two are possible, and there are restrictions due to the ionic radius and the like. In view of such conditions, both are arbitrarily selected, and water-soluble inorganic substances containing them are each dissolved in water to prepare a water-soluble inorganic aqueous solution as described below. Here, it goes without saying that there may be a plurality of types of cations or anions contained in one type of aqueous solution. In addition, as described above, so that an insoluble nonflammable inorganic substance containing two or more types of the above cation or anion moieties is generated,
A treatment liquid may be included. For example, the above-mentioned halogen and OH anion may be contained together in an aqueous solution containing the above-mentioned cation and/or another aqueous solution containing the above-mentioned anion, so as to produce apatite etc. in the wood. be. In the production method of the present invention, three aqueous solutions are prepared: two water-soluble inorganic aqueous solutions which are mixed to produce an insoluble non-flammable inorganic substance as described above, and a water-soluble inorganic aqueous solution which is mixed with one of the two to produce an insoluble non-flammable inorganic substance. Use. For example, when producing a salt that is an insoluble, nonflammable inorganic substance as described above, this combination includes Ca ²⁺ , Ba ²⁺ ,
a first aqueous solution containing at least one kind of ions that can constitute a cation moiety, such as Mg ²⁺ and Al ³⁺ ;
BO ₃ ^3- , PO ₄ ^3- , CO ₃ ^2- , SO ₄ ^2- , Cl ^- , F ^- , Br ^- ,
a second aqueous solution containing at least one kind of ions that can constitute an anion moiety such as OH ^- , and
Examples include a combination of either the first or second aqueous solution and the third aqueous solution within the same range. The first or second aqueous solution and the third aqueous solution may have exactly the same composition. The first aqueous solution is prepared by dissolving in water a water-soluble inorganic substance containing any of the ions that can constitute the cation moiety, and the second aqueous solution is prepared by dissolving in water any of the ions that can constitute the anion moiety. It can be obtained by dissolving a water-soluble inorganic substance containing water in water. The order of impregnation with the three aqueous solutions is, for example, after impregnating with the first aqueous solution and the second aqueous solution in order, and then impregnating with the first aqueous solution.
The third aqueous solution is impregnated in the same range as the aqueous solution. The first aqueous solution and the third aqueous solution may have the same composition. After the second aqueous solution and the first aqueous solution are impregnated in this order, the third aqueous solution may be impregnated in the same range as the second aqueous solution. In the method for producing modified wood according to the present invention, two water-soluble inorganic aqueous solutions are used because the three water-soluble inorganic aqueous solutions described above are used to generate insoluble, non-flammable inorganic substances in the cells of the wood. It is possible to generate and immobilize a large amount of insoluble and nonflammable inorganic substances in wood compared to the case of the present invention.
It is possible to efficiently obtain a product that has excellent antiseptic and insect repellent properties, as well as highly excellent dimensional stability, mechanical strength, and flame retardancy. It was also found that it is possible to obtain modified wood that does not impair its wood texture. Next, examples will be described. Example 1 2 mm thick rotary veneers made of pine, cedar, beech, and agathis were immersed in water,
The water was saturated under reduced pressure of about 30 Torr. next,
The obtained saturated veneer was mixed with 2.0 BaCl ₂ per 1 water.
Aqueous solution containing 2.0 moles of H ₃ BO ₃ (first bath)
Immersion in an aqueous solution containing 4.0 mol of (NH ₄ ) ₂ HPO ₄ and 6.0 mol of H ₃ BO ₃ per 1 water (second bath)
Then, the veneer was immersed in an aqueous solution having the same composition as the first bath (third bath) to form an insoluble, nonflammable inorganic substance in the veneer. Thereafter, the veneer was washed with water and dried to obtain modified wood. The obtained modified wood contained a large amount of insoluble incombustible inorganic substances, with 100 insoluble incombustible inorganic substances being combined with 100 in the absolute dry weight of the wood. The obtained modified wood was examined for its antiseptic and insect repellent properties, flame retardance, mechanical strength, and dimensional stability. The results are shown in Table 1.
However, insect repellency is determined by the insect mortality rate (%) in 3 weeks according to JWPA Standard No. 11, antiseptic property is determined by the weight loss rate (%) in 6 weeks according to JWPA Standard No. 1, and flame retardance ( Fire resistance) is determined by the calorific value tdθ (℃・min) and smoke generation coefficient CA (Cs・min) when burning for 10 minutes according to JIS A1321.
m ² ), mechanical strength was determined by bending strength (3-point bending, 17 mm LVL, Kg/cm ² ) according to JIS Z2113, and dimensional stability was determined by anti-swelling (anti-shrinkage ability) ASE. The results are shown in Table 1 along with the performance of the veneer.

〔Effect of the invention〕

The method for producing modified wood according to the present invention consists of three water-soluble inorganic aqueous solutions: two water-soluble inorganic aqueous solutions that produce an insoluble non-combustible inorganic substance when mixed, and a water-soluble inorganic aqueous solution that produces an insoluble non-flammable inorganic substance when mixed with one of the two. By separately impregnating with an aqueous solution, insoluble, non-combustible inorganic substances are fixed within the wood structure, resulting in excellent rot and insect repellency, as well as highly dimensional stability, mechanical strength, and flame retardancy. can be obtained efficiently.
Furthermore, it is also possible to obtain modified wood whose wood texture is not impaired.

Claims (1)

[Scope of Claims] 1. Three aqueous solutions of two water-soluble inorganic aqueous solutions that produce an insoluble non-flammable inorganic substance when mixed with one of them and a water-soluble inorganic aqueous solution that produces an insoluble non-flammable inorganic substance when mixed with one of the two, separately. A method for producing modified wood, characterized by fixing an insoluble, nonflammable inorganic substance within the wood structure by impregnating it. 2 Two of the three water-soluble inorganic aqueous solutions are
Alkali metals, alkaline earth metals, Zn and Al
It contains at least one kind selected from the group consisting of cations, and the remaining one is BO ₃ ,
The method for producing modified wood according to claim 1, which contains at least one selected from the group consisting of PO ₄ , CO ₃ , SO ₄ and OH anions.