JPH0520241B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field] This invention relates to a method for producing modified wood used as building materials and the like. [Background technology] As a method for modifying wood, it is possible to produce flame retardant (fire retardant),
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) Covering with inorganic substances (b) Promoting carbonization (c) Inhibiting chain reaction in flaming combustion (d) Generating nonflammable gas (e) Absorbing heat due to decomposition and releasing crystal water (f) Insulating with foam layer Here, The method of modifying wood by adding insoluble and non-combustible inorganic substances is particularly effective for the above-mentioned methods described below.
The effects of (a), (b), (c), and (d) are expected. Moreover, once this insoluble, nonflammable inorganic substance is fixed in the wood structure, there is little risk of it leaching out of the wood, so there is little worry that its effects will diminish, making it an effective method. In the above, (a) 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 an appropriate blending ratio. For example, the conventionally known wood chip cement board is made by mixing combustible wood with noncombustible cement at a weight ratio of approximately 1:1, and is formed into a board shape. It is recognized as. The carbonization promotion in (b) has 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 in (c) is contributed by halogen, and as a result of the halogen acting as a chain transfer agent in the radical oxidation reaction in the flame, the oxidation reaction is inhibited. This is the mechanism by which the flame retardant effect occurs. Therefore, if the insoluble, nonflammable inorganic substance contains a 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 have the effect of diluting combustible gases and preventing combustion. be. 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 preservatives wood, the mycelium first invades the wood's internal cavity, but if foreign matter is present in the wood's internal cavity, the mycelium's invasion is blocked, and as a result, the wood becomes less susceptible to decay. . The foreign matter in the wood lumen does not have to be a particularly antiseptic agent (preservative), and may be anything as long as it does not provide nutrients for fungi. Insect repellent is the same as preservative; if it has a medicinal effect, there is no need to worry about it, and there are also things that are poorly digestible, indigestible, or have a repellent effect against insects. preferable. Therefore, if an insoluble, nonflammable inorganic substance that satisfies these conditions is included in the internal cavity of wood, it is effective for preventing wood from rotting and insects. Furthermore, for 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, then
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 filled with filler, the wood itself is less likely to expand or contract, and at the same time, various mechanical strengths, particularly hardness, are improved. Here, inorganic substances that are difficult to dissolve in water can also be used as the fixing substance, so if an insoluble non-flammable inorganic substance is fixed in the wood cell wall,
That effect can be obtained. 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, for example, an insoluble nonflammable inorganic substance is directly dispersed in a solvent such as water, and this dispersion (processing liquid) is
Even if you try to soak the wood in it and allow the liquid to penetrate into the wood, the only thing that is difficult to penetrate is almost always a solvent such as water. This is because the narrowest part of the passage through which the treatment liquid permeates into the wood is the pit membrane, where the pore diameter is approximately 0.1 μm, while the dispersed particles The particle size of the insoluble, nonflammable inorganic material is usually 0.1μ
This is because it is much larger than m. 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 impregnated into sequential raw wood to cause both ions to react inside the wood. This is a method for producing modified wood that fixes insoluble, nonflammable inorganic substances (Japanese Patent Application No. 1989-089423). If you do this,
Although extremely large amounts of insoluble, nonflammable inorganic substances can be efficiently incorporated into wood, on the other hand,
Even now, the following problems remain. Normally, when immersion treatment is performed, during the second and subsequent immersion, the components that were previously impregnated in the wood flow out and react not only inside the wood but also outside the wood, that is, in the treatment bath. There was a problem that insoluble and nonflammable inorganic substances were generated. Since these contaminate the bath and lead to an increase in the amount of chemicals used, it is important to suppress their formation outside the wood as much as possible, and to generate a sufficient amount of insoluble, nonflammable inorganic substances almost exclusively within the wood. It is preferable. To this end, efforts have been made so far to make the concentration of the treatment liquid for later impregnation equal to or higher than the concentration of the treatment liquid for earlier impregnation, or to provide a sufficient impregnation time. However, when wood is treated under these conditions, the components that are subsequently impregnated exceed the amount necessary to react with the components previously contained in the wood to form insoluble, nonflammable minerals. Inevitably, too much was injected, which caused a different kind of problem. In other words, the unreacted ions left in the wood and the soluble inorganic substances as by-products absorb a lot of water and are hygroscopic, and depending on the type, may also exhibit deliquescent properties. Therefore, if too many of these remain in the wood, the water absorption and hygroscopicity of the wood will become too high. As a result, the resulting modified wood has a sticky feel,
Under high humidity conditions, the surface of the wood becomes wet, making it unsuitable for use as building materials. Therefore, leaching treatment is usually performed after impregnation treatment to remove these soluble components remaining inside the wood and improve the water resistance and weather resistance of the wood. This leaching treatment is carried out by providing a post-treatment bath and immersing the material in water for a long time, or leaving it in running water for washing. On the other hand, regarding the appearance of modified wood, that is, its wood texture, when it is dried after treatment, the insoluble and nonflammable inorganic substances generated near the wood surface precipitate white, making the entire wood white as if it had been dusted with powder. There was also the problem that it would wear out and its appearance would be damaged.
To this end, in the past, treated wood was washed to remove inorganic substances from the surface to maintain its appearance. However, as a new issue, some of the soluble inorganic substances removed by the above leaching process,
Depending on the type, it is also nonflammable and contains many components that can contribute to not only flame retardant wood but also mechanical strengthening and dimensional stabilization, so this soluble inorganic material is simply removed. In the end, these effective ingredients are completely wasted, and a large amount of chemicals are consumed, leading to an increase in manufacturing costs, and the above-mentioned performance of the wood is also reduced accordingly. This is a very important issue in view of the current situation where ever higher standards are required in terms of mechanical strength, dimensional stability, and especially flame retardancy, and it is difficult to meet these demands. On the other hand, there is a large loss of time due to the long leaching process, and the cost of the water required cannot be underestimated. As described above, conventionally, in order to obtain modified wood with excellent performance, various processes have been required over a long period of time, consuming large amounts of chemicals and time. Therefore, not only the quality of modified wood, but also
At present, further improvements are desired in terms of processing efficiency. [Objective of the Invention] In view of the above circumstances, the present invention utilizes the chemicals necessary for the modification treatment without wasting it, fixes a large amount of insoluble, non-combustible inorganic substances in wood, and improves its antiseptic and insect repellent properties, mechanical strength, and The purpose of the present invention is to provide a method for efficiently producing modified wood that has excellent dimensional stability, hygroscopicity, etc., highly flame retardant properties, and good appearance. [Disclosure of the Invention] In order to achieve the above object, the present invention provides two or more anion-containing treatment liquids and cation-containing treatment liquids that produce insoluble, non-flammable inorganic substances when mixed with raw material wood to be modified. A method for producing modified wood in which the inorganic substances are generated and fixed in the wood structure by impregnating each of the above-mentioned inorganic substances individually, wherein both of the processing solutions are impregnated alternately by immersion three times or more in total, and The gist of the present invention is a method for producing modified wood, characterized in that the final impregnation is carried out with an anion-containing treatment solution having a higher concentration than the previously used anion-containing treatment solution. This invention will be explained in detail below. The raw material wood for modification used in this invention is not particularly limited, and examples include raw logs, sawn timber products, sliced veneers, and plywood. There are no limitations on these tree species either. Prior to impregnation, it is preferable to subject the raw material wood to a water saturation treatment so that the wood is sufficiently saturated with water, for example, to a water content of about 70% or more. This is because the ions in the treatment liquid can diffuse quickly as water in the wood acts as a medium, and the impregnation time can be shortened. Examples of the above-mentioned water saturation treatment methods include underwater wood storage, 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. Examples include salts, silicic acids, nitrates, fluorides, bromides, hydroxides, etc., and two or more types of inorganic substances may coexist in the wood. Further, one type of insoluble nonflammable inorganic substance may contain two or more types of each of the following cation moiety and/or anion moiety. As the elements constituting the cation portion of the above-mentioned inorganic compound (salt), alkali metal elements such as Na and K, alkaline earth metal elements such as Mg, Ca, Sr, and Ba, Zn and Al can be used. Preferably, but not limited to, for example,
Transition elements such as Mn, Ni, and Cd and carbon group elements such as Si and Pb can also be used. The anion part is composed of BO ₃ ,
Preference is given to using PO ₄ , CO ₃ , SO ₄ and OH anions. However, it is not limited to these, and includes, for example, F, Cl, Br, O, NO ₃ ,
It may be SiO ₄ , SiO ₃ anion, or the like.
For BO ₃ and PO ₄ anions, the flame retardant mechanism is
The effect of (b), the effect of (d) for CO ₃ anions, and the effects of (c) and (d) for F, Cl, and Br anions are expected, so they are more suitable. The cation moiety and the anion moiety may be used alone or in combination. Here, not all combinations of the two are possible, and there are restrictions due to the ionic radius and the like. In view of such conditions, both of them are arbitrarily selected, and water-soluble inorganic substances containing them are respectively dissolved in water to form a cation-containing treatment liquid (X) and an anion-containing treatment liquid (Y). Prepare an aqueous solution of more than one type of water-soluble inorganic substance. Two or more types means that X and Y may each have the same composition, or X ₁ , X ₂ , X ₃ . . . and Y ₁ with different compositions,
Y ₂ , Y ₃ ... may also be prepared. Here, it goes without saying that there may be a plurality of types of cations or anions contained in one type of aqueous solution. In addition, as described above, so that an insoluble nonflammable inorganic substance containing two or more types of the above cation or anion moieties is generated,
A treatment liquid may be included. For example, the above-mentioned halogen and OH anion may be contained together in a cation-containing treatment solution and/or an anion-containing treatment solution containing other anions, so that apatite or the like is produced in the wood. It's good. The raw material wood is separately and alternately impregnated with these two treatment solutions.
A feature of the present invention is that the final anion-containing treatment liquid Y' has a higher concentration than any of the Y used previously. There are no particular limitations on the concentration of other treatment liquids, the number of times of impregnation, the order of impregnation, etc., and can be set as appropriate depending on the purpose. For example, impregnation methods include YXY′,
Examples include YXY...XY', XY...XY', etc., and X, Y, and Y' may be of the same type or different types. Here, if we start with impregnation with anion-containing treatment liquid Y, the effective impregnation treatment according to the present invention can be achieved with at least three impregnations, which is more efficient than impregnation with cation-containing treatment liquid X. It is preferable because The immersion time in each bath is not particularly limited, but from the second bath onwards, ions diffused into the wood react to form insoluble and nonflammable inorganic substances, and the immersion time is not limited to any particular time. Since the inorganic substances contained in the water may impede penetration, it is also effective to gradually lengthen the immersion time in order to further satisfactorily impregnate the ions. After the above impregnation treatment is completed, the wood is dried to obtain modified wood. Note that in order to further improve the water resistance of the wood after the impregnation treatment, a bath removal treatment may be performed as a post-treatment, or washing with water or the like may be performed. The method for producing modified wood according to the present invention includes, firstly,
Since the immersion treatment is performed three or more times in total, it has the following advantages. That is; wood can be sufficiently impregnated with a large amount of inorganic substances. Secondly, since a highly concentrated anion-containing treatment liquid is used for the final renewal, the following advantages are also obtained. In other words; the diffusion rate of anions into the wood becomes faster, and the cationic components contained within the wood react inside the wood without leaking out to the outside, so that insoluble and nonflammable inorganic substances The formation is suppressed, and it becomes possible to generate and fix a large amount of insoluble and nonflammable inorganic substances within the wood.
In other words, it is possible to prevent the loss of inorganic substances outside the wood, utilize chemicals efficiently, reduce manufacturing costs, and obtain modified wood with highly superior performance. Anion components can remain as ions remaining in the wood. This anion component is
Usually, it has higher performance in terms of fire retardancy than cationic components, so it greatly contributes to making the modified wood flame retardant. In this way, soluble components can be effectively utilized without performing leaching treatment, and at the same time, the processing time for this is shortened.
Processing baths, processing liquids, etc. are also not required. Insoluble and nonflammable inorganic substances present on the wood surface are
It is eluted by a high concentration anion impregnation treatment solution. In other words, the surface of the wood is cleaned by the final impregnation, and it is possible to obtain modified wood with an excellent appearance that retains its wood feel without the need for a separate cleaning process after the impregnation treatment. Next, Examples and Comparative Examples of the present invention will be described. Example of manufacturing method for modified wood 1 A 3mm thick rotary veneer made of hemlock wood is immersed in water and subjected to water saturation treatment under reduced pressure of about 30Torr.
The inside of the wood was sufficiently impregnated with water. _The obtained saturated veneer was soaked _{in an} anion _impregnating solution ₍ No. 1 bath) for 24 hours. Next, this veneer was mixed with 2.0 mol of barium chloride [BaCl ₂ ] and 2.0 mol of orthoboric acid per 1 mol of water.
Cation-containing treatment liquid in which moles are dissolved (second bath)
It was then immersed for 24 hours in an anion-containing treatment solution (third bath) in which 4.0 mol of diammonium hydrogen phosphate and 6.0 mol of orthoboric acid were dissolved per 1 water, resulting in an insoluble and non-combustible material in the wood. produced organic inorganic substances. After this immersion treatment, the veneer was washed with water and dried to obtain a modified wood. Examples 2 to 5, Comparative Examples 1 to 3 As in Example 1, the veneer that had been subjected to water saturation treatment was
Each modified wood was produced by processing under the conditions shown in the table. Performance of Modified Wood The modified wood obtained above was examined for total impregnation rate of inorganic substances, flame retardancy (fire retardancy), and appearance. 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 produce insoluble non-flammable inorganic substances) to the weight of bone dry wood without washing treatment. be. Flame retardancy is JIS standard
Flame retardant grade in A1321 is ◎, flame retardant grade is △,
The intermediate performance is ○, and the appearance is ◎, where no inorganic substances are observed on the wood surface, and △, where white, insoluble, nonflammable inorganic substances are observed over the entire wood surface. Those were marked as ○. The above results are shown in Table 1.

【table】

〔Effect of the invention〕

The method for producing modified wood according to the present invention is as described above, and in order to generate and fix an insoluble incombustible inorganic substance inside the wood, impregnating the wood with a treatment solution containing cations and anions alternately at least three times in total by dipping, In addition, because the final impregnation is performed with a treatment solution containing anions with a higher concentration than the anion-containing treatment solution used earlier, mechanical strength, dimensional stability, etc. are good, and it is highly difficult to resist. This makes it possible to efficiently produce modified wood that is flammable and retains its wood feel.

Claims (1)

[Scope of Claims] 1. Raw material wood to be modified is impregnated with two or more types of anion-containing treatment liquid and cation-containing treatment liquid that produce insoluble, non-combustible inorganic substances when mixed, and the process is carried out within the wood structure. A method for producing modified wood in which the above-mentioned inorganic substances are generated and fixed in the wood, wherein both of the above-mentioned treatment solutions are alternately impregnated by immersion impregnation three times or more in total, and the last impregnation is carried out using the previously used anion. A method for producing modified wood, characterized in that the process is carried out using an anion-containing treatment solution having a higher concentration than the treatment solution containing the anion. 2. The method for producing modified wood according to claim 1, wherein the first impregnation is with an anion-containing treatment liquid. 3. At least one of the cation-containing treatment liquids that produce an insoluble nonflammable inorganic substance when mixed contains at least one cation selected from the group consisting of alkali metals, alkaline earth metals, zinc, and aluminum cations. is a solution containing seeds,
and at least one of the anion-containing treatment liquids.
Claim 1 or 2, wherein the species is a solution containing at least one anion selected from the group consisting of BO ₃ , PO ₄ , CO ₃ , SO ₄ and OH anions. Process for producing modified wood.