JPH0560763B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] This invention relates to a method for producing modified wood used as housing equipment, building materials, etc. [Prior art] As a method for modifying wood, by producing insoluble and non-combustible inorganic substances in wood, it improves flame retardancy (fire retardancy), dimensional stability, antiseptic and insect repellent properties, mechanical strength,
Methods of imparting surface hardness and the like 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 modification method of adding insoluble and nonflammable inorganic substances to wood is as explained below.
In addition to (a), depending on the type of inorganic material, (b), (c), and (d)
This is an excellent method that can also be expected to have effects such as Moreover, once these insoluble, nonflammable inorganic substances are fixed in the wood structure, there is little risk of them leaching out of the wood, so there is little chance that their effects will wear off. 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 about 1:1 and forming it into a board shape, and is classified as a quasi-noncombustible material by JIS. It recognized. 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, so if the insoluble nonflammable inorganic substance contains a phosphoric acid component or a boric acid component, the flame retardant effect of this modified wood will be 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 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, hyphae first invade the inner cavity of the wood, but if foreign matter is present in the lumen of the wood, this prevents the mycelium from entering, and as a result, the wood becomes less likely to rot. . 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. The same applies to insect prevention as to preservatives. However, it is acceptable for foreign substances to have a medicinal effect; for example, it is preferable to use substances that are poorly digestible or indigestible to insects, or substances that have a repellent effect. Therefore, if an insoluble, nonflammable inorganic substance is included in the inner cavity of wood, it is effective for preventing wood from rotting and insects. Furthermore, regarding the dimensional stability and mechanical strength of wood, for example, if wood is swollen with water and some substance can be fixed in the wood cell walls in that state, both of the above properties will be improved due to the bulk effect. In other words, if the inside of the wood cell wall is occupied by the filler, the wood itself is less likely to expand or contract, and at the same time, various mechanical strengths are improved. Here, as the immobilizing substance, an inorganic substance that is difficult to dissolve in water can be used, so if an insoluble incombustible inorganic substance is immobilized in the wood cell wall, such an effect can be obtained. Finally, regarding the hardness of wood (surface hardness),
Generally, in order to increase the hardness of wood, it is sufficient to stuff hard substances such as inorganic substances into the voids such as conduits inside the wood and the cell walls of the wood. The effect of reinforcing cells and increasing hardness can be obtained. 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 making it flame retardant, 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 let the liquid penetrate into the wood, almost all that penetrates is the 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 substance is usually
This is because it is considerably larger than 0.1 μm. Therefore, the inventors have first developed a method that can solve this problem. That is, two types of aqueous solutions containing separately cations and anions (referred to as "cation-containing treatment liquid" and "anion-containing treatment liquid" in this order) that react to produce an insoluble nonflammable inorganic substance when mixed are prepared. This is a method for producing modified wood (Japanese Unexamined Patent Publication No. 61-246003) in which both ions are sequentially impregnated into raw material wood to react with both ions inside the wood, thereby fixing the insoluble and nonflammable inorganic substance. In this way, extremely large amounts of insoluble, nonflammable inorganic substances can be efficiently incorporated into the wood. [Problems to be Solved by the Invention] However, it has been found that there is still room for improvement in the water resistance and moisture resistance of the modified wood obtained as described above. In view of these circumstances, the present invention has developed a method for producing modified wood that has excellent flame retardancy, dimensional stability, antiseptic and insect repellent properties, mechanical strength, etc., as well as higher water and moisture resistance. The challenge is to provide. [Means for Solving the Problems] In order to solve the above problems, the present invention provides raw material wood to be modified with an aqueous solution of two or more water-soluble inorganic substances that produce insoluble non-flammable inorganic substances when mixed. A method for producing modified wood in which insoluble incombustible inorganic substances are produced and fixed in the wood fibers by impregnating them individually, and curing treatment is performed after completing the individual impregnation treatment with the two or more water-soluble inorganic aqueous solutions. The method is characterized in that at least a portion of the individual impregnation treatments of the two or more types of water-soluble inorganic aqueous solutions are further impregnated. Furthermore, the curing treatment includes at least one of ultrasonic vibration, microwave heating, pressurization, and heating.
Preferably, this is carried out by applying physical stimulation to the species. [Function] In the present invention, curing treatment is performed after completing the individual impregnation treatments of the two or more types of water-soluble inorganic aqueous solutions, and at least part of the individual impregnation treatments of the two or more types of water-soluble inorganic aqueous solutions are performed. By performing a curing treatment during the impregnation process, the reaction of unreacted ions contained in the wood to insoluble, non-flammable inorganic substances is promoted, and eventually A large amount of insoluble and nonflammable inorganic substances are generated and fixed in the wood. As a result, other properties are improved, among others: water resistance,
Moisture resistance is significantly improved. [Example] The raw material wood for modification used in the present 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. Insoluble, nonflammable inorganic substances that are generated in wood and dispersed and fixed in the wood tissue are not particularly limited, but include, for example, borates, phosphates, hydrogen phosphates, carbonates, sulfates, and hydrogen sulfates. ,
Examples include silicates, nitrates, hydroxides, and the like. Two or more types of these inorganic substances may coexist in the wood. In addition, in one type of insoluble nonflammable inorganic substance, the cation and/or anion moiety described below is
Two or more types of each may be included. More specifically, examples of the elements of the cation part of the insoluble nonflammable inorganic include alkali metals such as Na and K, alkaline earth metals such as Mg, Ca, Sr, and Ba, Zn, and Al. , transition elements such as Mn, Ni, and Cd, and carbon group elements such as Si and Pb, and are not particularly limited. Examples of anions constituting the insoluble, nonflammable inorganic substance include BO ₃ , PO ₄ , CO ₃ , SO ₄ and OH anions. In particular, BO ₃ and PO ₄ anions are more suitable because they provide the effect of the flame retardant mechanism (b), and CO ₃ anions provide the effect of the same mechanism (d). However, it is not limited to these, and includes, for example, O, NO ₃ , SiO ₄ , SiO ₃ , F,
It may be Cl, Br anion, etc. 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 to being used alone, the above-mentioned OH anions are also included in a cation-containing treatment solution and/or an anion-containing treatment solution containing other anions, so as to produce apatite etc. in the wood. It may be prepared. Examples of inorganic substances that dissolve in water to produce the desired cations include MgCl ₂ , MgBr ₂ , MgSO ₄ H ₂ O,
Mg(NO ₃ ) ₂・6H ₂ O, CaCl ₂ , CaBr ₂ , Ca
(NO ₃ ) ₂ , BaCl ₂・2H ₂ O, BaBr ₂ , Ba(NO ₃ ) ₂ ,
AlCl ₃ , AlBr ₃ , Al ₂ (SO ₄ ) ₃ , Al(NO ₃ ) ₃・9H ₂ O,
Examples include ZnCl ₂ and the like, but are not limited thereto. Examples of inorganic substances that dissolve in water to produce the desired anion include:
Na ₂ CO ₃ , (NH ₄ ) ₂ CO ₃ , H ₂ SO ₄ , Na ₂ SO ₄ ,
(NH ₄ ) ₂ SO ₄ , H ₃ PO ₄ , Na ₂ HPO ₄ ,
Examples include (NH ₄ ) ₂ HPO ₄ , H ₃ BO ₃ , NaBO ₂ , and NH ₄ BO ₂ , but are not limited thereto. 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. One of the above cation/anion-containing treatment liquids (the first liquid) is impregnated into the wood by immersing the raw material wood in the same treatment liquid. At this time, prior to the impregnation treatment, it is recommended to subject the raw material wood to a water saturation treatment so that the wood is sufficiently saturated with water. This is because the ions in the first liquid can diffuse quickly using the water in the wood as a medium, and the processing time can be shortened. Here, the water saturation treatment method is not particularly limited, and may include submerged wood storage, steaming, impregnation under reduced pressure, impregnation under pressure, and the like. Next, the wood is similarly impregnated with a treatment liquid (second liquid) containing ions that react with the first liquid to generate insoluble nonflammable inorganic substances, thereby generating the same insoluble nonflammable inorganic substances inside the wood. After that, if necessary, add a third liquid and a fourth liquid.
A solution may be prepared and impregnated repeatedly to make the product layer denser. 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. Furthermore, the impregnation method and time of the first liquid, second liquid, etc. are not particularly limited, and for example, impregnation may be carried out under reduced pressure or impregnation may be carried out by coating. can. In addition, the first
When the liquid is impregnated under reduced pressure, it is not necessary to perform the above-mentioned water saturation treatment. The above is the impregnation treatment, but the feature of this invention is that the curing treatment is performed in the middle of the impregnation treatment. Any method may be used as long as it promotes the inorganic substance production reaction.
Specifically, it can be performed by applying physical stimulation such as ultrasonic vibration, microwave heating, pressurization, and heating, but is not particularly limited. For more details, please refer to the above ultrasonic vibration.
This can be carried out using any equipment (for example, an ultrasonic cleaner, etc.), and it is preferable to carry out this while applying heat. It is preferable to set conditions such that microwave heating can be carried out for a long period of time at a reduced output so that the temperature of the wood does not rise too much and reaches an appropriate temperature. In the case of pressurization, if the pressure is too high, the equipment will become bulky and the wood structure may be compressed and destroyed, so it is appropriate to carry out the process under a pressure of, for example, 10 kg/cm ² or less. . Furthermore, it is usually preferable to set the heating to room temperature to 100°C. However, each curing treatment condition is not limited to the above examples, and for example, the treatment time should be set appropriately to ensure that these reactions are sufficiently carried out, depending on the amount of unreacted ions contained in the wood. Bye. In addition, when performing the above-mentioned microwave heating, heating, etc., it is preferable to seal the wood by wrapping it, etc., so that the moisture in the wood does not evaporate. The above-mentioned curing treatment can be carried out any number of times at any stage during the impregnation process, and is carried out in a state where both cations and anions capable of producing insoluble, non-flammable inorganic substances are present in the wood. Specifically, impregnation and curing treatments can be performed, for example, in the following order. ●Anion impregnation → cation impregnation → curing → anion impregnation ● cation impregnation → anion impregnation → curing → cation impregnation ● cation impregnation → anion impregnation → cation impregnation →
Curing → Anion impregnation ● Cation impregnation → Anion impregnation → Curing → Cation impregnation → Anion impregnation → Curing ● Anion impregnation → Cation impregnation → Anion impregnation →
Cation impregnation → curing → anion impregnation After the above impregnation and curing treatments generate and fix insoluble incombustible inorganic substances in the wood, if necessary, the surface of the wood is washed with water, etc., dried, and the modified wood is is obtained. In addition, in order to further 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. Next, more detailed examples of the present invention will be described together with comparative examples, but it goes without saying that the method for producing modified wood according to the present invention is not limited to the following example. Example 1 A 3 mm thick rotary veneer made of agathis material was immersed in water and subjected to water saturation treatment under reduced pressure of about 30 Torr.
The inside of the wood was sufficiently impregnated with water. The obtained saturated veneer was mixed with 3.5 mol of diammonium hydrogen phosphate and orthoboric acid per 1 water.
immersed in an aqueous solution containing 4.0 mol (first solution), then an aqueous solution containing 2.0 mol of barium chloride and 2.0 mol of orthoboric acid per 1 water (second solution).
immersed in it. The treated wood was then sealed and cured at a constant temperature of 60°C for 12 hours. Finally, diammonium hydrogen phosphate per 1 water
The veneer was immersed in an aqueous solution (third solution) containing 8.0 mol and 6.0 mol of orthoboric acid, and then washed with water.
After drying, modified wood was obtained. Examples 2 to 5 In the same manner as in Example 1 above, impregnation treatment using the immersion treatment liquid shown in Table 1 and curing treatment were performed to obtain modified wood. In addition, in the microwave heating of Example 3, high frequency output was applied to the sealed wood.
It was set to run for 15 minutes at 180W and oscillation frequency of 2450MHz. Comparative Examples 1 and 2 Modified wood was obtained by impregnating it with the treatment solution shown in Table 1 in the same manner as in the above example, except that the curing treatment was not performed during the impregnation treatment. Comparative Example 3 Modified wood was obtained in the same manner as in Example 1, except that heat curing was performed after the second liquid immersion treatment, and the subsequent impregnation treatment was not performed. Comparative Example 4 Modified wood was obtained in the same manner as in Example 1, except that after the second liquid immersion treatment, a third liquid immersion treatment was performed, and finally heat curing was performed. The modified wood obtained above was examined for its impregnation rate with insoluble and nonflammable inorganic substances, water resistance, and moisture resistance. The above inorganic substance impregnation rate is the weight ratio of insoluble, nonflammable inorganic substance impregnated to the weight of bone-dry wood. Regarding water resistance, water resistance A test (80℃, 1 hour hot water immersion → 60℃, 2 hours drying → After soaking in hot water at 80°C for 1 hour → drying at 60°C for 2 hours), the wood was kept in an absolutely dry state and the weight loss rate was examined. If it was less than 3%, it was ○, and if it was more than 3%, it was △. It was evaluated as
Moisture resistance: 60℃, 90%RH, 48 hours → 20℃, 65%
RH, 24 hours → -20℃, 24 hours → 20℃, 65%RH,
After conducting a 24-hour moisture resistance test, keep it in an absolutely dry state and check the weight loss rate. If this is 5% or less, 〇,
When it exceeded 5%, it was evaluated as △. The above results are also shown in Table 1.

〔Effect of the invention〕

According to the method for producing modified wood according to the present invention, modified wood with even higher water resistance and moisture resistance can be efficiently obtained. At the same time, this modified wood has excellent flame retardancy, dimensional stability, antiseptic and insect repellent properties, mechanical strength, appearance, etc., and has advanced performance that makes it ideal as a building material.

Claims (1)

[Scope of Claims] 1. Raw material wood to be modified is individually impregnated with an aqueous solution of two or more water-soluble inorganic substances that produce insoluble non-flammable inorganic substances when mixed, so that the same insoluble non-flammable inorganic substances are produced within the wood structure. In the method for producing modified wood that generates and fixes inorganic substances, curing treatment is performed after completing the individual impregnation treatments of the two or more types of water-soluble inorganic aqueous solutions, and then the individual impregnation treatments of the two or more types of water-soluble inorganic aqueous solutions are performed. A method for producing modified wood, which comprises performing at least part of an impregnation treatment. 2. The curing treatment according to claim 1, wherein the curing treatment is performed by applying a physical stimulus, and the physical stimulus is at least one of ultrasonic vibration, microwave heating, pressurization, and heating. Process for producing modified wood.