JPH042403B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a method for producing modified wood used as building materials and the like.

[Background technology]

By incorporating insoluble and nonflammable inorganic compounds into the wood,
A method for producing modified wood has been developed to obtain modified wood that has flame retardancy, antiseptic/insect repellent properties, and dimensional stability.

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 during 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 compound is included, in addition to the above (a), depending on the type of inorganic compound,
(b), (c) Effects from other mechanisms can be obtained. Moreover, insoluble and nonflammable inorganic compounds are
Since there is little chance of it melting out of the wood, there is also little chance of it becoming less effective.

The mechanisms of (a), (b) and (c) will be explained in detail below. Even if the inorganic material coating (a) is a combustible material, 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 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 decomposes and generates flammable gas, which ignites and burns.
The presence of phosphoric acid or boric acid promotes the thermal decomposition or carbonization of wood. The carbonized layer thus formed acts as a heat insulating layer and produces a flame retardant effect. Therefore, when the insoluble nonflammable inorganic compound contains a phosphoric acid component or a boric acid component, it has a high flame retardant effect. (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,
When the insoluble nonflammable inorganic compound contains a halogen, it has a high flame retardant effect.

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 inner cavity of the wood. However, if foreign matter is present in the internal cavity of the wood, mycelium cannot enter, and as a result, the wood becomes less susceptible to decay. The foreign matter in the wood lumen need not be a particularly antiseptic agent, 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 compound is included in the internal cavity of wood, the antiseptic and insect repellent properties of wood can be improved.

Furthermore, dimensional stabilization of wood will be explained.
If wood can be swollen and some substance can be fixed in the wood cell walls, dimensional stability can be achieved due to the bulk effect. Inorganic substances that are difficult to dissolve in water can also be used as immobilizing substances. Therefore, dimensional stability can be improved by fixing insoluble, nonflammable inorganic compounds into the wood cell walls.

However, in general, even if an insoluble, nonflammable inorganic compound 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, nonflammable inorganic This is because the particles of the compound are usually much larger than 0.1 μm.

Therefore, by impregnating wood with one of two types of aqueous solutions of water-soluble inorganic compounds that produce insoluble non-flammable inorganic compounds when mixed, and then impregnating wood with the other, an insoluble non-flammable inorganic compound is produced within the wood structure. The current practice is to disperse and fix the particles. This is because an aqueous solution can be easily impregnated into the structure of wood. More specifically, for example, two aqueous solutions separately containing ions that can react to produce an insoluble, nonflammable inorganic compound are prepared by dissolving the water-soluble inorganic compound in water, and both aqueous solutions are sequentially dissolved. Impregnate the wood. Then, the ions react with each other in the wood to form an insoluble, nonflammable inorganic compound.

However, when modified wood was produced using this method, the following problems arose.
In other words, in many cases, a larger amount of insoluble, nonflammable inorganic compounds are generated on the surface of the wood than inside the wood, which causes the problem that the wood surface of the wood is lost and the loss of insoluble, noncombustible inorganic compounds increases. be. In addition, when wood is immersed in a treatment bath containing an aqueous solution, a large amount of insoluble and nonflammable inorganic compounds are generated in the treatment bath that is subsequently immersed, making it impossible to reuse the treatment bath, and The question is when the loss of non-flammable inorganic compounds becomes so great.

[Purpose of the invention]

This invention was made in order to solve these problems, and it is possible to efficiently generate insoluble and nonflammable inorganic compounds inside wood, and it also has flame retardant properties without impairing the wood texture of the surface. , preservative
The object of the present invention is to provide a method for producing modified wood that can provide excellent insect repellency and dimensional stability.

[Disclosure of the invention]

In order to achieve the above objectives, the inventors have conducted repeated research. As a result, Ba ions and _BO3
We discovered that it is sufficient to impregnate wood with an aqueous solution containing ions and an aqueous solution containing BO ₃ ions and PO ₄ ions separately to generate insoluble, nonflammable inorganic compounds in the wood, and hereby we have developed this method. Completed the invention.

Therefore, this invention impregnates wood with one of two types of aqueous solutions of water-soluble inorganic compounds that produce insoluble non-flammable inorganic compounds when mixed, and then impregnates wood with the other. A method for producing modified wood in which an insoluble noncombustible inorganic compound is dispersed and fixed in the first aqueous solution.
Aqueous solution containing Ba ions and BO ₃ ions, second
The gist is a method for producing modified wood characterized by using an aqueous solution containing BO ₃ ions and PO ₄ ions.

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.

In the manufacturing method of the present invention, a first aqueous solution containing Ba ions and BO ₃ ions by dissolving a water-soluble inorganic compound in water, and a second aqueous solution containing BO ₃ ions and PO ₄ ions. Use an aqueous solution of Examples of inorganic compounds that generate Ba ions when dissolved in water include BaCl ₂ ,
BaBr ₂ , Ba(NO ₃ ) ₂ , Ba(OH) _{2 ,} etc. are used, and a plurality of types may be used in combination.
Inorganic compounds that dissolve in water to produce BO ₃ ions include, for example, H ₃ BO ₃ , NaBO ₂ and
KBO ₂ or the like may be used, and multiple types may be used in combination. Examples of inorganic compounds that generate PO ₄ ions when dissolved in water include H ₃ PO ₄ ,
Na ₃ PO ₄ , Na ₂ HPO ₄ , NaH ₂ PO ₄ , (NH ₄ ) ₃ PO ₄ ,
(NH ₄ ) ₂ HPO ₄ and NH ₄ H ₂ PO ₄ etc. are used,
Multiple types may be used together.

The first and second treatment liquids are impregnated into the wood in sequence. Either of the first and second treatment liquids may be impregnated first. After this, each ion is reacted under alkaline conditions, usually by impregnating the wood with an alkaline treatment liquid.
Then, an insoluble, nonflammable inorganic compound is produced in the wood to obtain modified wood. PH of alkaline processing solution
is usually PH8 or higher, preferably
It is best to set the pH to 8-10. Impregnation with the treatment liquid is performed, for example, by immersing the wood in a treatment bath containing the treatment liquid.

The insoluble nonflammable inorganic compound obtained in the above reaction includes M ₁₀ (ZO ₄ ) ₆ X ₂ (M: Ba, Z: B, P,
Examples include apatite having the basic structure of X:OH, Cl, Br, □). Here, □ is a vacancy. Apatite is B as Z,
It may include P at the same time, or it may include 2 at the same time as X.
It may contain more than one species. Furthermore, it may also contain water of crystallization.

By producing modified wood in this way, it is possible to sufficiently impregnate the inside of the wood with the treatment liquid before an insoluble, nonflammable inorganic compound forms on the surface of the wood, making it difficult for the treatment liquid to penetrate inside. For this reason, insoluble nonflammable inorganic compounds can be efficiently generated inside the wood, and less insoluble nonflammable inorganic compounds are generated on the wood surface. There are also fewer compounds. Therefore, there is little loss of insoluble, nonflammable inorganic compounds, and there is very little risk that the wood texture of the wood surface will be impaired. Furthermore, if an insoluble, non-combustible inorganic compound is produced within the structure of the wood, a modified wood with excellent flame retardancy, antiseptic/insect repellent properties, and dimensional stability can be obtained. Note that since BO ₃ ions and PO ₄ ions are used, an insoluble, nonflammable inorganic compound containing a boric acid component and a phosphoric acid component is produced. Therefore, the flame retardance of the resulting modified wood is extremely high. If an insoluble nonflammable inorganic compound containing a halogen is generated by using a solution of BaCl ₂ or BaBr ₂ in the first aqueous solution, the flame retardance of the resulting modified wood will be very high. becomes.

Next, examples will be described.

Example 1 A 3 mm thick rotary veneer made of beech wood was immersed in water at room temperature and left under reduced pressure of about 30 Torr for 5 hours to saturate it with water. This saturated veneer was treated with BaCl ₂ and
After being immersed in a first treatment bath containing a mixed aqueous solution of H ₃ BO ₃ (first treatment liquid),
(NH ₄ ) ₂ HPO ₄ and H ₃ BO ₃ mixed aqueous solution (second
The sample was immersed in a second treatment bath containing a treatment solution (treatment solution). Next, it was immersed in a third treatment bath containing an alkaline aqueous solution with a pH of 8 to 10. Then,
A modified wood (wood-inorganic composite) containing 50% of an insoluble, nonflammable inorganic compound (inorganic substance) per 100% of the bone dry weight of the wood was obtained.

This modified wood had excellent flame retardancy, antiseptic and insect repellent properties, and dimensional stability, and moreover, the woody texture of the surface was not lost. Furthermore, while the first treatment solution was of course reusable, the second and third treatment baths also did not generate much precipitate and could be reused.

Example 2 In the same manner as in Example 1, a 3 mm thick rotary veneer made of beech wood was saturated with water, and further treated with BaCl ₂ and
A treatment with a mixed aqueous solution of H ₃ BO ₃ (first treatment liquid) and a treatment with a mixed aqueous solution of (NH ₄ ) ₂ HPO ₄ and H ₃ BO ₃ (second treatment liquid) were performed. After this, the veneer was impregnated with an alkaline aqueous solution under reduced pressure. As a result, a modified wood (wood-inorganic composite) containing 50 parts of an insoluble and nonflammable inorganic compound (inorganic substance) per 100 parts of the bone dry weight of the wood was obtained.

This modified wood had excellent flame retardancy, antiseptic and insect repellent properties, and dimensional stability, and moreover, the woody texture of the surface was not lost. Furthermore, while the first treatment bath was of course reusable, the second treatment bath also did not generate much precipitate and could be reused.

Example 3 Instead of a mixed aqueous solution of BaCl ₂ and H ₃ BO ₃ ,
A modified wood (wood-inorganic composite) was obtained in exactly the same manner as in Example 1, except that a mixed aqueous solution of BaBr ₂ and H ₃ BO ₃ was used as the first treatment liquid.

This modified wood had excellent flame retardancy, antiseptic and insect repellent properties, and dimensional stability, and moreover, the woody texture of the surface was not lost. Further, the first treatment bath was of course reusable, but the second and third treatment baths also did not generate much precipitate and could be reused.

Example 4 Instead of the mixed aqueous solution of (NH ₄ ) ₂ HPO ₄ and H ₃ BO ₃ , Na 2 HPO 4 and Na ₂ HPO ₄ and
In addition to using a mixed aqueous solution of H ₃ BO ₃ ,
Modified wood (wood-inorganic composite) was obtained in exactly the same manner as in Example 1.

This modified wood had excellent flame retardancy, antiseptic and insect repellent properties, and dimensional stability, and moreover, the woody texture of the surface was not lost. Further, the first treatment bath was of course reusable, but the second and third treatment baths also did not generate much precipitate and could be reused.

〔Effect of the invention〕

The method for producing modified wood according to the present invention involves impregnating wood with one of two aqueous solutions of water-soluble inorganic compounds that produce insoluble non-flammable inorganic compounds when mixed, and then impregnating wood with the other. A method for producing modified wood in which an insoluble, nonflammable inorganic compound is dispersed and fixed in the wood structure, the first aqueous solution containing Ba ions and BO ₃ ions, and the second aqueous solution containing BO ₃ ions and PO ₄ ions. Since we use an aqueous solution that contains insoluble, non-combustible inorganic compounds inside the wood, we can efficiently generate insoluble and non-combustible inorganic compounds inside the wood, and it has excellent flame retardancy, antiseptic and insect repellent properties, and dimensional stability without impairing the wood texture of the wood surface. Modified wood can be obtained.

Claims (1)

[Claims] 1. One of the aqueous solutions of two types of water-soluble inorganic compounds that produce insoluble, non-combustible inorganic compounds when mixed is impregnated into wood, and then the other is impregnated into the wood tissue. A method for producing modified wood in which an insoluble nonflammable inorganic compound is dispersed and fixed, using an aqueous solution containing Ba ions and BO ₃ ions as the first aqueous solution, and an aqueous solution containing BO ₃ ions and PO ₄ ions as the second aqueous solution. A method for producing modified wood characterized by: 2 The insoluble nonflammable inorganic compound is M ₁₀ (ZO ₄ ) ₆ X ₂
(M: Ba, Z: B, P, X: OH, Cl, Br, □)
A method for producing modified wood according to claim 1, which is apatite having a basic structure of: 3. The first liquid contains Ba ions derived from at least one selected from the group consisting of BaCl ₂ , BaBr ₂ , Ba(NO ₃ ) ₂ and Ba(OH) ₂ , and H ₃ BO ₃ ,
The method for producing modified wood according to claim 1 or 2, which contains BO ₃ ions derived from at least one selected from the group consisting of NaBO ₂ and KBO ₂ . 4. The second liquid is derived from at least one species selected from the group consisting of H ₃ BO ₃ , NaBO ₂ and KBO ₂
BO ₃ ion, and H ₃ PO ₄ , Na ₃ PO ₄ ,
Na ₂ HPO ₄ , NaH ₂ PO ₄ , (NH ₄ ) ₃ PO ₄ ,
(NH ₄ ) ₂ HPO ₄ and NH ₄ H ₂ PO ₄ containing PO ₄ ions derived from at least one selected from the group consisting of A method for producing modified wood.