JPH04105902A - Modified lumber and manufacture thereof - Google Patents

Abstract

PURPOSE:To improve the fire resistance, rot proofness and insect proofness of lumber and reduce the deterioration on standing of its mechanical strength by a method wherein an insoluble, incombustible inorganic substance is produced and fixed in the lumber structure and the lumber is thereafter immersed in water to incorporate therein an unreacted water-soluble inorganic substance in an amount of at most a specific percentage. CONSTITUTION:A cation-containing treating liquid and an anion-containing treating liquid are prepared by dissolving the water-soluble inorganic substances containing cation and anion separately in water and material lumbers are immersed in either of them (a first liquid) to be impregnated therewith. Such lumbers are thereafter impregnated with the other treating liquid (a second liquid) containing the opposite ions reactive with the first liquid in order to produce an insoluble, incombustible inorganic substance in the lumber. The lumber thus impregnated is immersed in water or cured to enhance the reactivity of a water-soluble inorganic substance and thereafter dried to incorporate therein an unreacted water-soluble inorganic substance of the lumber being modified in a amount of at most 5wt.% based on the absolute dry weight of the material lumber in order to reduce the rate at which the water-soluble inorganic substance destroys the lumber structure and, for this reason, the deterioration on standing of a mechanical strength of the modified lumber can be controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to modified wood used as housing equipment, building materials, etc., and a method for producing the same.

[Conventional technology]

As a wood modification method, by incorporating insoluble and nonflammable inorganic substances into wood, flame retardance (fire retardance), dimensional stability,
Research and development are being conducted on methods to impart antiseptic and insect repellent properties, mechanical strength, surface hardness, etc.

In general, modification methods for imparting flame retardancy to wood are broadly classified based on the mechanism of the N-fuel ratio as described below.

(al Coating with inorganic substances (bl Carbonization promotion (C) Inhibition of chain reaction in flaming combustion (dl
Generation of non-flammable gas (e) Heat absorption due to decomposition and release of crystallized water (fl) Insulation by foam layer Here, the modification method of incorporating insoluble non-flammable inorganic substances into wood is as explained below. ), depending on the type of inorganic substance, (bl, (C), (d)
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 tendency for the melt to come out of the wood, so there is little concern that the above-mentioned effects will be diminished.

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.

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, but if phosphoric acid, boric acid, sulfuric acid, sulfurous acid, or their salts are present in the wood,
These inorganic substances cause a hydrolysis reaction of the C-0C bond that connects the glucose units of wood cellulose and cleave the same bond into COH and H0-C, which promotes the thermal decomposition of wood, that is, carbonization. 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, a boric acid component, a sulfuric acid component, a sulfite component, etc., the flame retardant effect becomes even higher.

(C) Inhibition of chain reactions in flaming combustion is contributed by halogens.In radical oxidation reactions in flames, halogens act as chain transfer agents, and as a result, oxidation reactions are inhibited. This is the mechanism by which the flame retardant effect occurs. Therefore, if the insoluble nonflammable inorganic substance contains a halogen, a flame retardant effect can also be obtained by this mechanism.

(The mechanism of generation of nonflammable gases in dl is as follows. In other words, compounds such as carbonates and ammonium salts generate nonflammable gases such as carbon dioxide gas, sulfur dioxide gas, and hydrogen halides through thermal decomposition. This is a mechanism in which these gases dilute combustible gases and thereby hinder combustion. Therefore, if the insoluble nonflammable inorganic substance contains carbonates or other substances that can generate nonflammable gases, H A combustion effect is also obtained.

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, mycelia cannot invade, resulting in the wood becoming less susceptible to decay. 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.

Additionally, dimensional stabilization and mechanical strengthening of wood will be discussed. 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. That is,
If the inside of the wood cell wall is occupied by filler, the wood itself will be less likely to expand or contract, and at the same time,
Various mechanical strengths are also improved. Here, as the immobilizing substance, inorganic substances that are difficult to dissolve in water can also be used. Therefore, if an insoluble nonflammable inorganic substance is fixed in the wood cell wall,
Dimensional stability and mechanical strength can be improved.

Finally, to explain how to improve the hardness (surface hardness) of wood, generally speaking, in order to increase the hardness of wood, you can stuff hard substances such as inorganic substances into the voids such as conduits inside the wood and into the cell walls of the wood. Therefore, by fixing insoluble, nonflammable 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, nonflammable inorganic substances is very effective in modifying wood, including flame retardation, 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 solution made of this dispersion to allow the treatment solution to penetrate into the wood, only Most of the time, only a solvent such as water is left. This is due to the following reasons. That is, the narrowest part of the path through which the treatment liquid passes when penetrating into the wood is the bit membrane run, and the pore diameter here is about 0.
1 μm, whereas particles of dispersed insoluble, non-flammable minerals are typically much larger than 0.1 μm.

Therefore, a method was developed to solve this problem. That is, two types of aqueous solutions separately containing cations and anions that react with each other to produce an insoluble nonflammable inorganic substance when mixed (hereinafter referred to as one cation-containing treatment liquid and an anion-containing treatment liquid in this order). is prepared by dissolving a water-soluble inorganic substance in water, and a rainwater solution is impregnated into the raw material wood in order to cause the above-mentioned ions to react in the wood, thereby producing an insoluble non-flammable inorganic substance. For the manufacturing method, see Japanese Patent Application Laid-open No. 61246003, etc.).

According to this method, insoluble noncombustible inorganic substances are not infiltrated as solid particles, but in the form of ions dissolved in a medium such as water, so impregnation is easy and extremely large amounts of insoluble noncombustible inorganic substances are infiltrated. It is possible to efficiently incorporate organic inorganic substances into wood. Therefore, it is possible to obtain modified wood that has extremely excellent antiseptic and insect repellent properties, dimensional stability, and the like.

Specifically, in this modification method, a cation-containing treatment liquid and an anion-containing treatment liquid are obtained by separately dissolving a water-soluble inorganic substance containing a predetermined cation and a water-soluble inorganic substance containing a predetermined anion in water. More specifically, a combination of treatment solutions containing a single water-soluble inorganic substance (a combination of single solution systems) is usually used.

For example, in a cation-containing treatment solution containing CaC1□,
The wood is impregnated with an anion-containing treatment liquid containing CO2, or a cation-containing treatment liquid containing AlCl (NH4) is impregnated with an anion-containing treatment liquid containing CO2.
! The wood is impregnated with an anion-containing treatment solution containing HPO4 to generate insoluble, nonflammable inorganic substances in the wood.

[Problem to be solved by the invention]

However, the modified wood obtained by the method described above has
Usually, the phosphoric acid, boric acid, sulfuric acid contained in the processing solution,
Unreacted water-soluble inorganic substances such as sulfite or their salts remain. As mentioned above, these water-soluble inorganic substances are
C-0 connects glucose units of wood cellulose
Although cutting the -C bond contributes to making the wood flame retardant, it also destroys the wood structure, causing a problem in that the mechanical strength of the wood deteriorates over time.

This invention was made in view of the above circumstances, and provides a modified wood with excellent N flammability, antiseptic and insect repellent properties, and less deterioration of mechanical strength over time, and a modified wood with the same property. The object of the present invention is to provide a method for efficiently obtaining wood.

[Means to solve the problem]

In order to solve the above-mentioned problem, the inventors have conducted intensive studies and found that by suppressing the content of unreacted water-soluble inorganic substances in the modified wood to 5% by weight or less based on the absolute dry weight of the raw material wood. They discovered that it is possible to reduce the deterioration of the mechanical strength of wood over time, and completed this invention.

That is, the modified wood according to the present invention can be obtained by impregnating raw material wood with one of the combinations of a cation-containing treatment liquid and an anion-containing treatment liquid that produce insoluble, nonflammable inorganic substances when mixed, and then impregnating the other. Modified wood in which the insoluble nonflammable inorganic substance is generated and fixed in the wood structure by a method, and the content of unreacted water-soluble inorganic substance is 5% by weight or less based on the absolute dry weight of the raw material wood. It is characterized by this.

In addition, the method for producing modified wood according to the present invention includes treating the raw material wood to be modified with one of a combination of a cation-containing treatment liquid and an anion-containing treatment liquid that produce insoluble and nonflammable inorganic substances when mixed. A method for producing modified wood in which the insoluble nonflammable inorganic substance is generated and fixed within the wood tissue by impregnating the wood with the other impregnating the wood, the method comprising producing and fixing the insoluble noncombustible inorganic substance within the wood structure. After that, the treated wood is immersed in water so that the content of unreacted water-soluble inorganic substances in the wood is 5% by weight or less based on the absolute dry weight of the raw material wood. It is something to do.

The raw material wood used in this invention is not particularly limited, and examples thereof include raw logs, sawn timber products, sliced veneers, plywood, and the like. There are no limitations on the tree species, etc.

In this invention, the insoluble and nonflammable inorganic substances (insoluble products) that are generated in wood and dispersed and fixed in the wood tissue are not particularly limited, but include, for example, borates,
Examples include various salts such as phosphates, hydrogen phosphates, carbonates, sulfates, hydrogen sulfates, silicates, nitrates, and hydroxides.

Among these salts, specific examples of carbonates include BaC0z, CaCO2, FeCO2, Mg
These include CO2, MnC○x, NiCO2, ZnC0z, etc. Two or more of these may coexist in the wood. The insoluble, nonflammable inorganic substance within the wood may be fixed in the form of a reaction with wood cellulose.

Note that one type of insoluble nonflammable inorganic substance may contain two or more types of each of the cation and/or anion moieties described below.

In order to generate the above-mentioned insoluble non-flammable inorganic substance within the wood tissue, an aqueous solution prepared with a group of inorganic compounds constituting the cationic part of the insoluble non-flammable inorganic substance, that is, a cation-containing treatment liquid, and an ayu-dan part. An aqueous solution prepared with another group of inorganic compounds, that is, an anion-containing treatment solution, is separately and sequentially impregnated into the wood structure. The cation-containing treatment liquid and the anion-containing treatment liquid can be impregnated alternately once or multiple times. When impregnating multiple times, the impregnation may be performed not alternately but continuously.

The cation moiety of the insoluble nonflammable inorganic substance includes, for example, alkali metals such as Na and C;
Alkaline earth metals such as a, Ba, Mg, Sr, Mn,
Transition elements such as Ni and Cd, carbon group elements such as Si and Pb,
Examples include Zn and Aff. Among these, C
a, Ba, Mg, Zn and Al cations are preferred.

Examples of the anion portion of the insoluble nonflammable inorganic substance include B4O7 and BO.

, PO4, CO2, SO4, NO2, C1,, Br, F
, T and CI1. Among these,
BO,l, PO4, CO2, SO4 and OH anions are preferred. Among the anions, B2O,,B
ow and PO4 are the effects due to the mechanism (b) above, CO3 is the effect due to the mechanism (dl), CI2
, FXBr and other halogens are used in the above (C1 and (d)
Effects can be expected from each mechanism.

The above cations and anions are arbitrarily selected depending on the composition of the desired insoluble, nonflammable inorganic substance to be produced in the wood, and by dissolving the water-soluble inorganic substances containing each of these ions in water separately, the desired A cation-containing treatment liquid containing cations and an anion-containing treatment liquid containing desired anions are prepared. However, the combination of the cation and anion is appropriately selected so that an insoluble incombustible inorganic substance is likely to be generated within the wood structure.

Examples of inorganic substances that dissolve in water to produce the desired cations include MgC#z, MgBrz, Mg5o4.H
zOlMg (Now)z ・6 H−○, CaCf
f2, CaBr2, Ca (NorizBa(1!-2
H20, BaBrz, Ba (No2)z, Aj
! C#z, AA B rt, Aj! z(S.O.
4)! , A7! (NO,), 9H20, Zn
(172 etc. are mentioned as an example, but are not limited to these. Examples of inorganic substances that dissolve in water to produce the above-mentioned desired anion include Na2Co2, (NH4)2
Co.

, ll2S○a , Na, SO4, (N■-14)2S
O4, Hz PO4, Na, HPO4, (NH4)2
HPOa, H2BO,, Na BO2, NH4BO2
These examples include, but are not limited to these examples. Each of the above water-soluble inorganic substances may be used alone, or a plurality of types may be used in combination in one treatment liquid within the range where a uniform aqueous solution can be formed without reacting with each other.

The inorganic substance impregnation treatment of the raw material wood using the cation-containing treatment liquid and the anion-containing treatment liquid described above is carried out, for example, as follows.

First, one of the two treatment liquids (the first liquid) is impregnated into the wood by immersing the lumber as a raw material in the same treatment liquid. After the first liquid is completely submerged, a treatment liquid (second liquid) containing ions that react with the first liquid is similarly impregnated to generate insoluble and nonflammable inorganic substances inside the wood.

Next, after the two liquids, the anion-containing treatment liquid and the cation-containing treatment liquid, are impregnated as described above, if necessary, a third liquid, a fourth liquid, etc. are prepared and repeated. The product layer may be densified by impregnation.

The cation/anion-containing treatment liquids used at this time may be of the same type or different types, and their concentrations are not particularly limited.

The impregnation treatment method and impregnation treatment time of the mixture are not particularly limited, and impregnation can be carried out under reduced pressure or pressure, or impregnation can be carried out by coating.

In addition, prior to the impregnation treatment with the first liquid, it is recommended that the raw material wood be subjected to a water saturation treatment so that the wood is sufficiently saturated with water. This is because the ions contained in the first liquid can be rapidly diffused using the water in the wood as a medium, and the processing time can be shortened. The water saturation treatment method is not particularly limited, but may be carried out by submerged wood storage, steaming, impregnation under reduced pressure, impregnation under pressure, or the like. In addition, the first
When the liquid is impregnated under reduced pressure or increased pressure, it is not necessarily necessary to carry out this water saturation treatment.

If the content of unreacted water-soluble inorganic substances in the modified wood in which insoluble non-combustible inorganic substances have been generated and fixed in the wood by the above impregnation treatment exceeds 5% by weight based on the absolute dry weight of the raw wood, It is necessary to perform a treatment such that the content of the water-soluble inorganic substance is 5% by weight or less. Methods for such treatment are not particularly limited, but include, for example, a method of soaking wood that has been impregnated as described above in water. The immersion time and the like are not particularly limited.

Further, a curing treatment may be performed to increase the reaction rate of water-soluble inorganic substances (promote the production reaction of insoluble nonflammable inorganic substances).

After performing the above treatment, if necessary, the surface of the wood is washed with water, etc., and dried to obtain the desired modified wood.

[For production]

When the content of unreacted water-soluble inorganic substances in the modified wood is 5% by weight or less based on the absolute dry weight of the raw material wood,
Since the rate at which the water-soluble inorganic substance destroys the wood structure is reduced, deterioration of the mechanical strength of the modified wood over time is suppressed.

〔Example〕

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 rotary I/S veneer made of Douglas fir and having a thickness of 5 mm was used as the raw material wood, and this veneer was subjected to a water saturation treatment to sufficiently impregnate the inside of the wood with water.

After the saturated water treatment, the veneer was soaked in a zinc chloride aqueous solution (concentration 1) at 50°C.
It was immersed for 4 hours in a first bath consisting of a 50° C. sodium dihydrogen phosphate aqueous solution (concentration 1 mol/water L A ) for 4 hours. The veneer was soaked in water for 24 hours.

After soaking, hot air drying was performed to obtain a modified wood veneer with a moisture content of 5 to 10%. The content of unreacted water-soluble inorganic substances in this modified wood veneer is 2% by weight based on the bone dry weight of the raw material wood.
Met.

The obtained modified wood veneers were laminated and bonded to produce a modified wood plywood.

Example 2 A sliced veneer made of pine wood with a thickness of 1111 mm was used as the raw material wood, and this veneer was subjected to water saturation treatment to sufficiently impregnate the inside of the wood with water.

After the saturated water treatment, the veneer was soaked in 60°C calcium chloride water/8
Sodium sulfate solution (a degree 1 mol/water 1 part) was immersed in the first bath for 3 hours, and then 60°C sodium sulfate aqueous solution (concentration 1
It was immersed in a second bath consisting of 1β mol/water for 4 hours.

Thereafter, the treated veneer was immersed in water for 12 hours.

After soaking, hot air drying was performed to obtain a modified wood veneer with a moisture content of 5 to 10%. The content of unreacted water-soluble inorganic substances in this modified wood veneer is 4% by weight based on the bone dry weight of the raw material wood.
Met.

The obtained modified wood veneers were laminated and bonded to produce a modified wood plywood.

Example 3 A rotary veneer made of agathis wood and having a thickness of 3 was used as the raw material wood, and this veneer was subjected to a water saturation treatment to sufficiently impregnate the inside of the wood with water.

After the saturated water treatment, the veneer was immersed in a first bath consisting of a 60°C magnesium sulfate aqueous solution (concentration 1 mol/water 1.ff) for 2 hours, and then immersed in a 60°C sodium carbonate aqueous solution (
The sample was immersed in a second bath containing 1 mol/water (IN) for 2 hours. Thereafter, the treated veneer was soaked in water for 16 hours.

After soaking, hot air drying was performed to obtain a modified wood veneer with a moisture content of 5 to 10%. The content of unreacted water-soluble inorganic substances in this modified wood veneer is 3% by weight based on the bone dry weight of the raw material wood.
Met.

The obtained modified wood veneers were laminated and bonded to produce a modified wood plywood.

Example 4 - A rotary veneer made of lauan wood with a thickness of 311 mm was used as the raw material wood, and this veneer was subjected to water saturation treatment to sufficiently impregnate the interior of the wood with water.

After the saturated water treatment, the veneer was soaked in a zinc chloride aqueous solution <'a at 60°C.
It was immersed in a first bath consisting of 1 mol of water/11 parts of water for 1 hour, and then a 60°C aqueous solution of sodium dihydrogen phosphate (a
1 hour for the second bath consisting of 2 mol/1 ff of water) +?
I did M. Thereafter, the treated veneer was immersed in water for 12 hours.

After soaking, hot air drying was performed to obtain a modified wood veneer with a moisture content of 5 to 10%. The content of unreacted water-soluble inorganic substances in this modified wood veneer was 1.5% by weight based on the bone dry weight of the raw material wood.

The obtained modified wood veneers were laminated and bonded to produce a modified wood plywood.

Example 5 A sliced veneer made of oak and having a thickness of l xx was used as the raw material wood, and this veneer was subjected to water saturation treatment to sufficiently impregnate the interior of the wood with water.

The veneer after the water saturation treatment was immersed in a first bath consisting of a magnesium carbonate aqueous solution (concentration 2 mol/water 11 at 50°C) for 4 hours, and then immersed in a 50°C aqueous phosphoric acid-sodium hydrogen solution ('a degree 2 mol/water 11). The treated veneer was then immersed in a second bath consisting of mol/water 112) for 18 hours.

After soaking, hot air drying was performed to obtain a modified wood veneer with a moisture content of 5 to 10%. The content of unreacted water-soluble inorganic substances in this modified wood veneer is 3% by weight based on the bone dry weight of the raw material wood.
Met.

The obtained modified wood veneers were laminated and bonded to produce a modified wood plywood.

Comparative Example 1 A rotary lace veneer made of Douglas fir wood with a thickness of 5 fl was used as the raw material wood, and this veneer was subjected to water saturation treatment to sufficiently impregnate the interior of the wood with water.

After the saturated water treatment, the veneer was soaked in a zinc chloride aqueous solution (concentration 1) at 50°C.
mol/water 1β) for 4 hours, and then immersed in a 50°C aqueous sodium dihydrogen phosphate solution (concentration 1β).
mol/1ff of water) for 4 hours. Thereafter, the treated veneer was immersed in water for 6 hours.

After soaking, hot air drying was performed to obtain a modified wood veneer with a moisture content of 5 to 10%. The content of unreacted water-soluble inorganic substances in this modified wood veneer is 8% by weight based on the bone dry weight of the raw material wood.
Met.

The obtained modified wood veneers were laminated and bonded to produce a modified wood plywood.

Comparative Example 2 A sliced veneer made of pine wood with a thickness of 1 dragon was used as the raw material wood, and this veneer was subjected to water saturation treatment to sufficiently impregnate the inside of the wood with water.

After the saturated water treatment, the veneer was immersed for 3 hours in a first bath consisting of a 60°C calcium chloride aqueous solution (1 mol/17 parts water), and then a 60°C sodium sulfate aqueous solution (concentration 1:1).
It was immersed in a second bath consisting of 1β mol/water for 4 hours.

Thereafter, the treated veneer was immersed in water for 2 hours.

After soaking, hot air drying was performed to obtain a modified wood veneer with a moisture content of 5 to 10%. The content of unreacted water-soluble inorganic substances in this modified wood veneer was 10% by weight based on the absolute dry weight of the raw material wood.

The obtained modified wood veneers were laminated and bonded to produce a modified wood plywood.

Comparative Example 3 Comparative Example 3 was a commercially available flame-retardant plywood (lauan material) containing ammonium phosphate and a boric acid-based inorganic salt.

The modified wood plywood obtained in Examples 1 to 5 and Comparative Examples 1 to 2 and the commercially available flame retardant plywood of Comparative Example 3 were subjected to a flame retardancy test and a test to accelerate mechanical strength deterioration over time. Ta. The flame retardance of the commercially available flame retardant plywood of Comparative Example 3 was evaluated as "○".
", and those inferior to the flame-retardant plywood were evaluated with "x". Deterioration of mechanical strength over time is defined as a case where the bending strength of plywood has decreased by 30% or more after being left in air at 75℃ for 8 weeks.
Those with a decrease in bending strength of less than 30% were evaluated as "small".

The above results are summarized in Table 1.

As shown in Table 1, regarding flame retardancy, Examples 1 to 5
The modified wood plywood obtained in Comparative Examples 1 and 2 was comparable to the commercially available flame-retardant plywood of Comparative Example 3. On the other hand, regarding the deterioration of mechanical strength over time, the modified wood plywood obtained in Comparative Examples 1 and 2 and the commercially available flame-retardant plywood of Comparative Example 3 show a large degree of deterioration in mechanical strength over time. On the other hand, it was confirmed that the modified wood plywood obtained in Examples 1 to 5 showed a small degree of deterioration in mechanical strength over time.

〔Effect of the invention〕

The modified wood according to the present invention has insoluble, nonflammable inorganic substances fixed therein, so it has excellent antiseptic, insect repellent, flame retardant properties, etc., and the content of unreacted water-soluble inorganic substances is
Since it is 5% by weight or less based on the absolute dry weight of the raw material wood,
Deterioration of mechanical strength over time is small.

Furthermore, since the modified wood has an inorganic substance impregnated inside the wood, the wood texture is not impaired, and the wood has excellent appearance as well as the above-mentioned performance.

Further, according to the method for producing modified wood according to the present invention, modified wood having the above-mentioned performance can be efficiently obtained.

Claims (1)

[Scope of Claims] 1. A combination of a cation-containing treatment liquid and an anion-containing treatment liquid that produces an insoluble, non-combustible inorganic substance when mixed into a raw material wood, and then impregnating the other one to form an insoluble inflammable inorganic substance. Modified wood in which the insoluble nonflammable inorganic substance is produced and fixed, characterized in that the content of unreacted water-soluble inorganic substance is 5% by weight or less based on the absolute dry weight of the raw material wood. modified wood. 2 The raw material wood to be modified is impregnated with one of the combinations of a cation-containing treatment liquid and an anion-containing treatment liquid that produce insoluble, non-combustible inorganic substances by mixing, and then the other is impregnated to improve the wood structure. A method for producing modified wood that generates and fixes the insoluble nonflammable inorganic substance within the wood structure, the process involves immersing the treated wood in water after producing and fixing the insoluble nonflammable inorganic substance within the wood structure. A method for producing modified wood, characterized in that the content of unreacted water-soluble inorganic substances in the wood is 5% by weight or less based on the absolute dry weight of the raw material wood.