JPH02252503A - Preparation of modified wood - Google Patents

Abstract

PURPOSE:To prepare modified wood excellent in fire retardancy, preservative/ mothproof properties and dimensional stability by increasing the impregnation amount of insoluble non-combustible inorg. matter in wood by preliminarily impregnating raw material wood with a surfactant prior to form the insoluble non-combustible inorg. matter. CONSTITUTION:Raw material wood is preliminarily impregnated with a surfactant prior to forming insoluble non-combustible inorg. matter. The impregnation treatment of the surfactant is performed, for example, by a method wherein the raw material wood is immersed in water containing the surfactant and heated. As the surfactant, a usual one, for example, an anionic surfactant, a cationic surfactant, a nonionic surfactant or an amphoteric surfactant is used. The raw material wood is successively impregnated with a cation- containing treatment solution and an anion-containing treatment solution to be subjected to the treatment with inorg. matters. At first, for example, the raw material wood impregnated with the surfactant is immersed in the cation- containing treatment solution to be impregnated with said solution and subsequently impregnated with the anion-containing treatment solution in the same way to form insoluble non-combustible inorg. matter in the wood.

Description

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

[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 is 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 following flame retardant mechanisms.

(al Coating with inorganic material (b) Promotion of carbonization (C1 Inhibition of chain reaction in flaming combustion (dl) Generation of nonflammable gas (Il!1) Endotherm due to decomposition and release of crystal water (f)
Here, the modification method of including an insoluble non-flammable inorganic substance in the wood is as follows: This is an excellent method that can also be expected to have effects due to mechanisms such as (d). Moreover, once the insoluble, nonflammable inorganic substance is fixed in the wood structure, there is little risk of melt coming out of the wood, so there is little worry that the effect will be diminished.

The mechanisms from Tal to (d) 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 decomposes and produces flammable gas.
This causes flaming combustion, but the presence of phosphoric acid or boric acid promotes thermal decomposition, or carbonization, of the wood.
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.

(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 be obtained by this mechanism.

+d) The generation of nonflammable gas 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 a substance capable of generating 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 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, it becomes difficult to rot. The foreign matter in the wood lumen need not be a particularly antiseptic agent (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 is swollen with water and some substance can be fixed in the wood cell walls in this state, dimensional stabilization and mechanical strength strengthening effects can be obtained due to the bulk effect. In other words, if the wood cell lumen is occupied by the filler, the wood itself is less likely to expand or contract, and at the same time, various mechanical strengths including hardness are improved. Here, as the immobilizing substance, inorganic substances that are difficult to dissolve in water can also be used. Therefore, fixing insoluble and noncombustible inorganic substances into wood cell walls can improve dimensional stability and mechanical strength.6Finally, regarding the hardness (surface hardness) of wood, in general, in order to increase the hardness of wood, It is sufficient to fill the voids such as conduits inside the wood and the cell walls of the wood with hard substances such as inorganic substances. By fixing insoluble, non-combustible inorganic substances in the wood, it is possible to strengthen the wood cells and increase hardness. can get. Here, it is more effective if the inorganic substances are generated 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 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 this dispersion (treatment liquid) to allow the liquid to penetrate into the wood, most of the material that penetrates is water. This results in only the solvent being used. 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 run, and the pore diameter here is approximately O01μ trap, whereas the insoluble nonflammable inorganic material dispersed The particle size is usually 0.11
This is because it is much larger than

Therefore, the inventors have previously developed a method that can solve this problem (see Japanese Patent Application Laid-Open No. 61-246003). In other words, by mixing, they react with each other to produce insoluble and nonflammable inorganic substances. Two types of aqueous solutions separately containing cations and anions (referred to as ``cation-containing treatment liquid'' and ``anion-containing treatment liquid'') were prepared by dissolving water-soluble inorganic substances in water. We developed a method in which insoluble, nonflammable inorganic substances are produced by impregnating raw material wood in order and reacting cations and anions in the wood.

According to this method, it is not infiltrated as solid particles, but in a state dissolved in a medium such as water, so impregnation is easy, and extremely large amounts of insoluble, nonflammable inorganic substances can be efficiently incorporated into the wood. I can do it. Therefore, it is possible to obtain modified wood with excellent rot and insect repellency and dimensional stability.

Furthermore, a number of improvements have been made in response to new problems with the aim of improving the performance of the negative layer.

[Problem to be solved by the invention]

Amid such research, the challenge is to further improve the performance of wood, including its flame retardancy, rot and insect repellency, and dimensional stability. One of the means to improve the above performance
One idea was to increase the amount of insoluble, nonflammable inorganic material impregnated.

Conventionally, in order to increase the amount of insoluble nonflammable inorganic substances impregnated, a method has been adopted in which the number of times wood is impregnated with an aqueous solution (treatment liquid) of two or more water-soluble inorganic substances that produce insoluble nonflammable inorganic substances by mixing has been adopted. It is being

However, it is desirable to increase the amount of insoluble and nonflammable inorganic material impregnated by a method that is more efficient than increasing the number of times the treatment liquid is impregnated.

In view of these circumstances, the present invention makes it possible to increase the amount of insoluble and nonflammable inorganic material impregnated into wood without increasing the number of times the wood is impregnated with a treatment liquid, thereby improving flammability, preservatives, and An object of the present invention is to provide a method for producing modified wood with excellent insect repellency and dimensional stability.

[Means to solve the problem]

In order to solve the above problems, the method for producing modified wood according to the present invention is a combination of a cation-containing treatment liquid and an anion-containing treatment liquid that produce an insoluble, non-flammable inorganic substance by mixing the raw material wood to be modified. In impregnating one of them and then impregnating the other to generate and fix the insoluble non-flammable inorganic substance in the wood tissue, prior to the generation of the insoluble non-flammable inorganic substance, the raw material wood is:
It is characterized by performing a surfactant impregnation treatment in advance.

The raw material wood for modification 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 produced in wood and dispersed and fixed in the wood tissue are not particularly limited, but include, for example, borates,
Examples include phosphates, hydrogen phosphates, carbonates, sulfates, hydrogen sulfates, silicates, nitrates, hydrides, and the like. Two or more of these may coexist in the wood. Moreover, these compounds may be fixed in the form of reacting with wood cellulose.

Moreover, one type of insoluble nonflammable inorganic substance may contain two or more types of each of the following cation and/or anion moieties.

Examples of the elements of the cation part constituting the above-mentioned insoluble nonflammable inorganic substance include alkali metals such as Na and Mg.
Preferred examples include alkaline earth metals such as , Ca, Sr, and Ba, Zn, and Al; for example, Mn,
It may also be a transition element such as Ni or Cd or a carbon group element such as Si or Pb (but is not particularly limited).

The anions constituting the above-mentioned insoluble nonflammable inorganic substance include:
B Os , P 04 , COs , S 04 and OH anions are given as examples. In the case of BO,, P04 anion, the effect due to the flame retardant mechanism), CO
, anion is more suitable because the effect of (d) can be obtained. However, it is not limited to these,
For example, F, Cj2, Br, 0% Not % Si
It may be an O4,5ins anion or the like.

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.

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.

Inorganic substances that dissolve in water to produce the desired cations include MgCJg, MgBrg, MgSO4'H
z 01Mg (Nos) * 6H1OlC
aClm, CaBrg, Ca(NOs)t
,BaCj!・2H,01BaBr*, Ba
(Not)s, Allclm, AIlBr
s , AJf(SO4)l , AIl (N 0x
)t @ 9 Hz O, Z n CIt z, etc. are listed as examples, but are not limited thereto. Inorganic substances that dissolve in water to produce the above desired anions include NamC0*, (NH4), Cot, H, S04
, Nag SOa, (NH4)* SO4, H-PO2
, Nag HPO4, (NH-)s HP O4,H
Examples include, but are not limited to, x BOt , NaBox , NH4Bog, etc. 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.

By sequentially impregnating the raw material wood with the above-described cation-containing treatment liquid and anion-containing treatment liquid, the raw material wood is treated with inorganic substances. In this invention, the raw material wood is impregnated with a surfactant prior to the production of the insoluble, nonflammable inorganic material.

The surfactant impregnation treatment is carried out, for example, by immersing the raw material wood in water containing the surfactant and heating it. As the surfactant, common surfactants are used, such as anionic surfactants, cationic surfactants, nonionic surfactants, amphoteric surfactants, etc.
It is not limited to these. The surfactant concentration of the water containing a surfactant is not particularly limited, but is 1 to 5% by weight.
is preferred. If the surfactant concentration is higher than this range,
It may have an adverse effect on wood, and at concentrations lower than this range, the surfactant may be less effective. In addition,
The surfactant impregnation treatment is not particularly limited, but it is preferably carried out by heating to around 80° C. This is to speed up the impregnation of water into the raw material wood. Furthermore, if the temperature of this impregnation treatment is too high than around 80℃, the water will evaporate rapidly and
If the temperature is too low, the water impregnation rate may be slow.

In the above description, the surfactant impregnation treatment and the water saturation (or hydration) treatment were performed at the same time, but the raw material wood may be subjected to the hydration treatment prior to the surfactant impregnation treatment.

The water treatment method is not particularly limited, and may include underwater wood storage, steaming, impregnation under reduced pressure, impregnation under pressure, etc.

The impregnation treatment of the raw material wood with both of the above-mentioned treatment liquids is carried out, for example, as follows, but if impregnation with a surfactant is performed prior to the production of insoluble, nonflammable inorganic substances, the method is limited to the following method. It's not a thing.

First, the raw material wood that has been impregnated with a surfactant as described above is immersed in one of the two treatment solutions (the first solution, for example, the cation-containing treatment solution). Impregnate the wood with liquid 1. At this time, prior to the impregnation treatment, as described above, if the raw wood is impregnated with a surfactant and the wood is sufficiently saturated with water, the water in the wood will be used as a medium to Another advantage is that the ions in the liquid can diffuse quickly, reducing processing time.

Next, the wood is similarly impregnated with a treatment liquid (second liquid, for example, an anion-containing treatment liquid) containing ions of the counterpart that reacts with the first liquid to generate insoluble and nonflammable inorganic substances inside the wood.

Note that heat treatment may be performed at any stage during a series of reaction steps, and thereby, for example, impregnation, reaction, etc. may be promoted and the effect of a -layer may be obtained.

After the insoluble, nonflammable inorganic substance is generated and fixed in the wood by the above impregnation treatment, the surface of the wood is washed with water, if necessary, and dried to obtain a modified wood. In addition, in order to improve the durability and weather resistance of the wood, if necessary, leaching treatment may be performed to remove soluble unreacted ions and byproducts left in the wood, or washing with water may be performed. The compounds formed on the surface layer of the wood may also be removed. The above-mentioned soluble components left in the wood absorb a large amount of water and moisture, and depending on the type, may exhibit deliquescent properties.
If too many of these remain, the water absorption and hygroscopicity of the wood will become too high. This may make the wood unsuitable for use as a building material, so these can be removed by leaching treatment to improve the water resistance and weather resistance of the wood. This leaching treatment is performed by providing a post-treatment bath and immersing the material in water for a long time, or leaving it in running water for washing. In addition, regarding the appearance of modified wood, that is, its wood texture, when it dries after treatment, insoluble compounds generated on the wood surface precipitate, making the entire wood look white and powdery, impairing its appearance. Therefore, it is effective to wash the wood after treatment to maintain its appearance. On the other hand, many of the above-mentioned soluble components are also nonflammable and can contribute not only to making wood flame retardant but also to improving its mechanical strength and dimensional stability. One way to improve the performance of the wood is to leave as much wood as possible. Also, if necessary,
It is also possible to perform curing after the impregnation treatment to promote the production reaction of insoluble and nonflammable inorganic substances.

In this invention, there are no limitations on the pretreatment liquid used, the order of impregnation, the number of times of impregnation, etc.; for example, the cation-containing treatment liquid and/or the anion-containing treatment liquid are repeatedly impregnated multiple times to densify the product layer. In the case where at least one of the two treatment liquids is impregnated multiple times alternately and/or continuously, the treatment liquids may be of the same type or different types. I don't mind.

In addition, the impregnation treatment method and impregnation treatment time of each liquid are not particularly limited, and impregnation can be carried out under reduced pressure or impregnation by coating. In this case, the water saturation treatment described above may not be performed.

In addition, in this invention, orthoboric acid, borax, and other boric acid compounds may be added to the cation-containing treatment liquid and/or the anion-containing treatment liquid, and at least one of these may be added. As a result, boric acid is expected to have a coating effect that suppresses gas generation in improving the flame retardancy of modified wood in combustion tests. When aiming at such a coating effect of boric acid, the proportion of boric acid used is not particularly limited, but it is preferably 2 to 6 mol/l. If it is more than this range, there is a risk that boric acid will precipitate, and if it is less than this range, there is a possibility that the covering action of boric acid will be insufficient.

The amount of bath used for the saturated water treatment, cation/anion impregnation treatment, leaching treatment, etc. is not particularly limited, but for example,
The amount is set to be approximately 10 times the weight of untreated wood.

[For production]

According to the method for producing modified wood according to the present invention, the moisture content of the wood (the ratio of the weight of impregnated water to the weight of the wood) increases, and the extracted components in the wood are dissolved into water. In this way, by increasing the moisture content in the wood, the anions and cations needed to create insoluble, nonflammable inorganic substances will enter the wood and become impregnated into every corner of the wood. Therefore, the amount of insoluble and nonflammable inorganic substances impregnated increases.Additionally, extractive components of wood that are difficult to dissolve in water can also be extracted into water by adding a surfactant.Some of these extracted components inhibit ionic reactions. Because quinones, etc., which are thought to cause the oxidation and retardation of Improves the performance of quality wood such as flame retardancy, rot/insect repellency, and dimensional stability.

〔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 3 tm thick rotary veneer made of agathis material is immersed in water containing a propylene glycol fatty acid ester surfactant (surfactant concentration 22% by weight) and heated at 80°C for 2 days. By doing this, water and surfactant were impregnated inside the veneer. The moisture content was 230%.

This water-containing veneer was dissolved in a first solution [an aqueous solution prepared by dissolving 3.5 moles of diammonium hydrogen phosphate ((NH4)s HP O4) and 4.0 moles of orthoboric acid to 11 moles of water. Temperature 60℃] for 24 hours, and then
Second liquid [barium chloride (BaCI18) to 11 parts water
An aqueous solution prepared by dissolving 2.0 mol of and 2.0 mol of orthoboric acid. Temperature: 60℃] for 24 hours, and then soaked in the third liquid (water: 17!). An aqueous solution prepared by dissolving diammonium hydrogen phosphate ((NH,), HPO,) in a proportion of 8.0 mol and orthoboric acid in a ratio of 6.0 mol. Temperature of 60℃] for 24 hours to generate and fix insoluble, nonflammable inorganic substances in the wood.Next, the surface of the wood was washed with water to remove deposits (part of the reaction products) on the surface. It was removed and dried to obtain modified wood.

Examples 2 to 5 - Modified wood was obtained in the same manner as in Example 1 above under the conditions shown in Table 1.

Comparative Example 1.2 Modified wood was obtained in the same manner as in Example 1, except that the water treatment was carried out under the conditions shown in Table 1 without using a surfactant.

The modified wood obtained in Examples 1 to 5 and Comparative Examples 1 and 2 was examined for moisture content, impregnation rate of insoluble and nonflammable inorganic substances, flame retardance, antiseptic/insect repellent properties, and dimensional stability.

Moisture content was determined by measuring the weight increase after water impregnation relative to the dry weight of the wood. The impregnation rate of insoluble nonflammable inorganic substances is
It was the ratio of the weight of the insoluble incombustible inorganic substance impregnated to the weight of the bone-dried wood. The flame retardance was evaluated as ◎ for flame retardant class ◎ in JIS A1321, △ for flame retardant class △, and ○ for intermediate performance. Preservative and insect repellent properties are evaluated by the rate of decrease in wood weight in response to decay and insect damage. ◎ indicates that the weight does not decrease at all, × indicates that it is equivalent to normal untreated wood, and ○ indicates that the weight is in the middle. evaluated. Dimensional stability is ASE
It is evaluated based on the improvement rate of dimensional change of untreated wood. Zero (0) means untreated wood, etc., 100 means no dimensional change, and the larger the value, the better. The results are shown in Table 1.

As shown in Table 1, when comparing samples with the same heating time during immersion in water, Examples 1 and 4 were more effective than Comparative Example 1.
Further, Examples 2 and 3 have higher water content and higher insoluble incombustible inorganic substance impregnation rate than Comparative Example 2, respectively.

〔Effect of the invention〕

As described above, in the method for producing modified wood according to the present invention, the raw material wood is impregnated with a surfactant in advance, prior to the production of insoluble and nonflammable inorganic substances.
The impregnation rate of insoluble nonflammable minerals increases.

Agent: Patent Attorney Takehiko Matsumoto

Claims (1)

[Claims] 1 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 when mixed, and then the other is impregnated to improve the wood structure. A method for producing modified wood in which the insoluble noncombustible inorganic substance is generated and fixed in the wood, characterized in that, prior to the production of the insoluble noncombustible inorganic substance, the raw material wood is impregnated with a surfactant in advance. A method for producing modified wood.