JPH01166905A - Manufacture of improved wood - Google Patents

Abstract

PURPOSE: To obtain a modified timber having a high woody feeling while maintaining excellent flame retardance or the like by generating and fixing an insoluble incombustible inorganic substance in the timber, and then dissolving the substance generated on a surface of the timber in an ammonium salt aqueous solution to remove it. CONSTITUTION: A raw material timber to be modified is individually impregnated with two or more types of aqueous soluble inorganic aqueous solutions for generating an insoluble incombustible inorganic substance by mixing to fix the inorganic substance in a timber tissue. After the impregnation with the treating liquid, the inorganic substance generated on a surface of the timber is dissolved in an ammonium salt aqueous solution and removed. Thus, a modified timber having excellent woody feeling can be obtained. Further, the timber is impregnated with the ammonium salt component to improve a flame retardance or the like of the timber. And, as an element for constituting a cation part of the inorganic compound (salt), an alkali metal element such as Na, K or the like, alkali earth metal element such as Mg, Ca, Sr, Ba or the like or Zn and Al are used. As an element for constituting an anion part, BO3 , PO4 , CO2 , SO4 or OH anion is preferably used.

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]

As a method of modifying wood, it is made flame retardant (fire retardant) by producing insoluble and nonflammable inorganic substances in wood.

Methods of imparting dimensional stability, antiseptic/insect repellent properties, mechanical strength, etc. are being researched and developed.

In general, modification methods for imparting flame retardancy to wood are broadly classified based on the following flame retardant mechanisms.

(a) Coating with inorganic material (b) Promotion of carbonization (inhibition of chain reaction in C1 flaming combustion (dl) Generation of nonflammable gas (e) Absorption of heat due to decomposition and release of crystal water ([1] Heat insulation by foam layer) The modification method of including an insoluble nonflammable inorganic substance will be explained below, but in addition to the above (a), it is an excellent method that can also be expected to have effects such as (kl) or d) depending on the type of inorganic substance. It is.

Moreover, once this insoluble, nonflammable inorganic substance is fixed in the wood structure, there is little possibility that it will be dissolved from the wood thereafter, so there is little worry that its effects will diminish.

In the above, fa) coating with an inorganic substance means that even if the material is flammable, it can be made flame retardant by combining it with a non-flammable inorganic substance at a suitable blending ratio. For example, the conventionally known wooden cement board is made by mixing combustible wood with non-combustible cement at a weight ratio of about 1:1 and forming it into a board shape.
It is recognized as a quasi-noncombustible material by IS standards.

The carbonization promotion in (b) is the following mechanism. In other words, when wood is heated, it thermally decomposes and generates flammable gas, which causes flaming combustion. At this time, if phosphoric acid or boric acid is present, the thermal decomposition, or carbonization, of the wood is promoted. A carbonized layer is quickly formed. This carbonized layer acts as a heat insulating layer and provides 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 of the modified wood becomes even higher.

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

Finally, the generation of nonflammable gas (d) will be explained.

This is because compounds such as carbonates and ammonium salts generate nonflammable gases such as carbon dioxide, sulfur dioxide, and hydrogen halides through thermal decomposition, but these gases dilute flammable gases and prevent combustion. It is. Therefore, if the insoluble nonflammable inorganic substance contains something that can generate the above-mentioned nonflammable gases, such as carbonate, a flame retardant effect due to this mechanism can also be obtained. .

Next, the antiseptic and insect repellent effects of wood containing this insoluble, noncombustible inorganic substance will be explained. When fungi cause wood to rot, mycelium first invades the inner cavity of the wood.
The presence of foreign matter in the internal cavity of the wood prevents mycelium from entering the wood, and as a result, the wood becomes less susceptible to decay. The foreign matter in the wood lumen does not need to be a particularly antiseptic agent (preservative), and may be anything as long as it does not provide nutrients for fungi. Insect repellents are the same as preservatives; if they have medicinal effects, they are no different, and they also have poor digestibility against insects.

It is preferable to use something that is hard to digest, something that is not digestible, or something that has a repellent effect. Therefore, if an insoluble, noncombustible inorganic substance that satisfies such conditions is included in the inner cavity of wood, it is effective in preserving the wood and preventing car damage.

Furthermore, regarding dimensional stabilization and mechanical strengthening of wood, if wood is swollen with water and some substance can be fixed in the wood cell walls in that state, both of the above 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 becomes less likely to expand or contract, and at the same time, various mechanical strengths, especially hardness, are improved. Here, as the immobilizing substance, an inorganic substance that is difficult to dissolve in water can also be used, so the effect can be obtained by immobilizing it in an insoluble, nonflammable state in the wood cell wall.

As described above, the method of incorporating insoluble nonflammable inorganic substances is very effective in modifying wood including flame retardation, but it has the following problems.

Generally 1. For example, if an insoluble nonflammable inorganic substance is directly dispersed in a solvent such as water, and wood is immersed in this dispersion (treatment liquid) to allow the liquid to penetrate into the wood, most of the material that penetrates is water, etc. Only the solvent will be left. This is because the narrowest part of the passage through which the treatment liquid permeates into the wood is the bitmen run.
The pore size here is about 0.1μ, whereas the particle size of the insoluble nonflammable inorganic particles, which are dispersed particles, is usually 0.1μ.
This is because it is much larger than μ.

Therefore, the inventors have first developed a method that can solve this problem. That is, two types of aqueous solutions are prepared that separately contain cations and anions that react to produce insoluble, nonflammable inorganic substances when mixed, and both are sequentially impregnated into raw wood to cause both ions to react inside the wood. This is a method for producing modified wood in which insoluble, nonflammable inorganic substances are fixed (Japanese Patent Application No. 6O-089423). In this way, it is possible to efficiently incorporate extremely large amounts of insoluble, nonflammable inorganic substances into the wood, but on the other hand, the following problems still remain regarding the appearance of the wood after treatment: .

Conventionally, when the wood is dried after impregnation, insoluble and nonflammable inorganic substances formed on the surface of the wood precipitate out, causing the wood to turn white as if it had been dusted with powder, impairing its appearance, or the feel of the wood. Ta. Therefore, treated wood has been washed with water to remove insoluble and non-combustible inorganic substances on the surface, but washing with water does not remove inorganic substances efficiently, resulting in a large loss of time, etc. There is a drawback. In addition, since the particles still cannot be removed sufficiently, it becomes necessary to remove them using tools or the like, and there is a risk that the performance of the wood will be impaired by such operations, and improvements have been desired.

C. Purpose of the Invention] In view of the above circumstances, the present invention fixes a large amount of insoluble, non-combustible inorganic material in wood, has excellent flame retardancy, antiseptic and insect repellent properties, mechanical strength, dimensional stability, etc. The purpose of the present invention is to provide a method for efficiently producing modified wood having a highly woody texture.

(Disclosure of the Invention) In order to achieve the above object, the present invention impregnates raw material wood to be modified individually with an aqueous solution of two or more water-soluble inorganic substances that produce insoluble incombustible inorganic substances when mixed. A method for producing modified wood in which the inorganic substances are fixed in the wood structure by using the treatment liquid, and the method is characterized in that after the impregnation treatment with the treatment liquid, the inorganic substances generated on the wood surface are removed by dissolving them with an aqueous ammonium salt solution. The gist of this paper is a method for producing modified wood.

The present invention will be explained in detail below.

The raw material wood for modification used in this invention is not particularly limited, and examples include log 9M wood products, sliced veneer 2 plywood, and the like. There are no limitations on these tree species either. - When impregnating under normal pressure, it is preferable to subject the raw material wood to water saturation treatment to sufficiently saturate the wood with water prior to impregnation with the treatment liquid described below. This is because the ions in the treatment solution can diffuse quickly using the water in the wood as a medium, reducing the impregnation time. Examples include steaming, impregnation under reduced pressure, and impregnation under pressure.

Insoluble, nonflammable inorganic substances that are generated in wood and dispersed and fixed in the wood tissue are not particularly limited, and include, for example, borates, phosphates, hydrogen phosphates, carbonates, sulfates, and hydrogen sulfate. salts, silicates, nitrates, fluorides,
Examples include bromides, hydroxides, etc., and two or more types of inorganic substances may coexist in the wood.

Furthermore, one type of insoluble, nonflammable inorganic substance may contain two or more types of cation moieties and/or anion moieties described below.

As the elements constituting the cation portion of the above-mentioned inorganic compound (salt), alkali metal elements such as Na and Ni, alkaline earth metal elements such as Mg, Ca, Sr, and Ba, Zn, and Al may be used. is preferable, but not limited to, for example, M n + N
Transition elements such as i+ Cd and carbon group elements such as Si and Pb can also be used.

BO constitutes the anion portion.

, po,', cot , BO4 and OH7 anions are preferably used. For BO8, P04 anions,
Since the effect of the flame retardant mechanism (b) and the effect of CO and anion (d) can be obtained, the - layer is preferable6. Br, O.

Now, SiO4,5ins anions, etc. may be used. In particular, halogen has the advantage that the effects of (C) and (d) can be expected together.

The cation portion and the anion portion may be used alone or in combination, but not all combinations are possible, and the ionic radius, etc. There are restrictions due to In view of such conditions, two or more types of the cation-containing treatment liquid and the anion-containing treatment liquid at arbitrary concentrations are prepared by arbitrarily selecting both of them and dissolving each of the water-soluble inorganic substances containing them in water. Prepare an aqueous solution of a water-soluble inorganic substance.

In addition, the above-mentioned halogens and OH anions can be used alone or included together in a cation-containing treatment liquid and/or an anion-containing treatment liquid containing other anions to produce apatite etc. in the wood. It may be prepared as follows.

The raw wood is impregnated with these two treatment solutions separately and alternately, but there are no particular restrictions on the impregnation method, number of impregnations, or order of impregnation, and it can be changed depending on the purpose. It can be set as appropriate.

A feature of the present invention is that after the above impregnation operation, insoluble and nonflammable inorganic substances generated on the wood surface are dissolved and removed by an aqueous ammonium salt solution. That is, by washing the impregnated wood by immersing it in an aqueous ammonium salt solution for a short time, inorganic substances can be efficiently removed and modified wood with excellent wood texture can be obtained. Furthermore, it has the advantage that the ammonium salt component penetrates into the wood and improves the flame retardance of the wood.

The anion moiety in the ammonium salt aqueous solution used includes, for example, PO4, Cot
, SO4, NOs, F, C1, Br and ■ ions, among which PO.

, COs, SO4, NOx, F, and C1 ions are preferably used.These ions may be used alone or in combination. Furthermore, the time period for which the wood is immersed in these aqueous solutions is not particularly limited, and can be set as appropriate depending on the thickness of the wood and the like. Note that this ammonium salt aqueous solution may have the same composition as other anion-containing treatment liquids that are not the final treatment liquid.

After the products on the surface of the wood are removed in this manner, the wood is lightly washed with water if necessary and dried to obtain modified wood.

In addition, in order to improve the water resistance and weather resistance of the wood, leaching treatment may be performed as necessary to remove soluble unreacted ions or by-products remaining in the wood. Such soluble components absorb a large amount of water and moisture, and depending on the type, they may exhibit deliquescent properties, so if too much of these components remain in the wood, the water absorption and moisture absorption properties of the wood will become too high. This is because the material may become unsuitable for use as a building material, etc. On the other hand, depending on the type of soluble components, there are many components that are nonflammable and can contribute not only to flame retardation of wood but also to mechanical strengthening and dimensional stabilization. One solution is to leave them in place and improve the performance of the wood accordingly.

Next, Examples and Comparative Examples of the present invention will be described.

■ Extracting 1 piece of wood (Example 1) A 31L thick rotary veneer of Japanese hemlock wood was immersed in water and subjected to water saturation treatment under reduced pressure of about 30 Torr to thoroughly impregnate the interior of the wood with water. I let it happen.

The obtained saturated veneer was immersed for 24 hours in an anion-containing treatment solution (first bath) in which 3.5 mol of ammonium hydrogen phosphate and 4.0 mol of orthoboric acid were dissolved per 1 p of water. Next, this veneer was immersed for 24 hours in a cation-containing treatment solution (second bath) in which 2.0 moles of barium chloride and 2.0 moles of orthoboric acid were dissolved per 1β of water, resulting in an insoluble and nonflammable substance in the wood. produced inorganic substances.

The wood after the above impregnation treatment was washed with water II! The veneer surface products were dissolved and removed by immersion for 4 hours in an aqueous ammonium salt solution in which 5.0 moles of ammonium nitrate and 2.0 moles of orthoboric acid were dissolved. Thereafter, the veneer was washed with water and dried to obtain modified wood.

(Examples 2 to 5) Similarly to Example 1, veneers subjected to water saturation treatment were treated under the conditions shown in Table 1 to produce modified wood. In Examples 2, 3, and 5, impregnation was also performed in the third bath.

(Comparative Examples 1 and 2) Modified wood was produced under the conditions shown in Table 1 in the same manner as in the above Example, except that the cleaning treatment with ammonium salt after the impregnation treatment was not performed.

■ Eing 1 tree forest ■ Parting plate Regarding the modified wood obtained above, the total impregnation rate of inorganic matter, n
Flammability (fire resistance) and appearance were investigated. The above-mentioned total impregnation rate of inorganic substances is the total impregnated weight ratio of insoluble non-flammable inorganic substances and unreacted ions (ions that do not generate insoluble non-flammable inorganic substances) to the weight of bone-dry wood. Flame retardancy is
According to JIS standard A1321, the flame retardant ■ class is ◎, the flame retardant ■ grade is △, and the intermediate performance is ○. Regarding the appearance, ◎ indicates that no inorganic substance formation is observed on the wood surface, and the wood surface is white and insoluble. Those in which the formation of nonflammable inorganic substances was observed were rated △, and those in the intermediate state were rated ○.

The above results are shown in Table 1.

As shown in Table 1, the modified wood of the example that was subjected to the ammonium salt treatment after the impregnation treatment contained a large amount of inorganic substances,
It was found that insoluble and non-combustible inorganic substances on the wood surface were efficiently removed and a good wood texture was obtained despite maintaining excellent flame retardancy. For it,
In the modified wood of the comparative example, a white product was deposited on the wood surface, and the appearance was poor.

〔Effect of the invention〕

The method for producing modified wood according to the present invention is as described above, and after producing and fixing an insoluble incombustible inorganic substance in wood,
Since the inorganic substances generated on the wood surface are dissolved and removed using an aqueous ammonium salt solution, the wood is highly This makes it possible to efficiently produce modified wood with texture.

Agent: Patent Attorney Takehiko Matsumoto

Claims (2)

[Claims] (1) The raw material wood to be modified is individually impregnated with an aqueous solution of two or more water-soluble inorganic substances that produce insoluble, nonflammable inorganic substances when mixed to fix the inorganic substances in the wood structure. A method for producing modified wood,
A method for producing modified wood, which comprises removing the inorganic substances generated on the surface of the wood by dissolving it in an aqueous ammonium salt solution after the impregnation treatment with the treatment liquid. (2) At least one of the two or more water-soluble inorganic aqueous solutions that produce an insoluble nonflammable inorganic substance when mixed is a member of the group consisting of alkali metal, alkaline earth metal, zinc, and aluminum cations. A solution containing at least one selected from the following, and at least one of the aqueous solutions includes BO_2, PO_4, CO_
2. The method for producing modified wood according to claim 1, wherein the solution contains at least one anion selected from the group consisting of 2, SO_4, and OH anions.