Method for producing modified wood material, furan derivative resin solution and modified wood material

Abstract

The present invention provides a method for producing a modified wood material. Specifically, the method comprises the following steps: 1) infiltrating a furan derivative resin solution into the wood material, the furan derivative resin solution containing a furan derivative, an inorganic salt that inhibits polymerization of the furan derivative at room temperature, and an inorganic salt that promotes polymerization of the furan derivative; and 2) heating the infiltrated furan derivative resin solution to polymerize the furan derivative in the wood material.

Description

Technical Field

[0001] The present invention relates to a method for modifying a wood material, that is, a method for producing a modified wood material (modified wood material). The present invention also relates to a solution used in the production method and a wood material modified by treatment with the solution. Background Art

[0002] Examples of wood materials include broadleaf timber and coniferous timber. For example, broadleaf timber from tropical areas is generally hard and resistant to decay, and is therefore used for furniture as well as interior materials such as wooden floors and exterior materials such as wooden outdoor treads.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application No. 2005-533688 Summary of the Invention

[0006] In order to make the wood material more suitable for use, it is considered to modify the wood material.

[0007] The purpose of the present invention is to modify wood materials.

[0008] The present inventors have conducted intensive research to address the above-mentioned issues and have discovered that using a furan derivative resin solution composed of a combination of a furan derivative and a specific inorganic salt as a solution for modifying wood materials provides a solution having improved stability as a wood material modification solution, and that the modification imparts excellent durability, hardness, and / or dimensional stability to the wood material. This has led to the completion of the present invention.

[0009] The present invention provides a manufacturing method, which is a manufacturing method of a modified wood material, comprising the following steps:

[0010] 1) a step of allowing a furan derivative resin solution containing a furan derivative, an inorganic salt that inhibits polymerization of the furan derivative at room temperature, and an inorganic salt that promotes polymerization of the furan derivative to penetrate into a wood material; and

[0011] 2) A step of polymerizing the furan derivative in the impregnated furan derivative resinification solution in the wood material by heating.

[0012] In addition, the present invention also provides a furan derivative resin solution suitable for use in the above-mentioned production method. Specifically, the present invention provides a furan derivative resin solution, which is a solution for modifying wood materials.

[0013] The furan derivative resinification solution contains a furan derivative, an inorganic salt that inhibits polymerization of the furan derivative at room temperature, and an inorganic salt that promotes polymerization of the furan derivative.

[0014] The present invention also provides a modified wood material obtained by the above-mentioned production method. Specifically, the present invention provides a modified wood material, which is a wood material modified by the above-mentioned production method and contains at least a polymerized furan derivative.

[0015] According to the invention, wood materials may be modified.

[0016] More specifically, the furan derivative resinified solution used for modification has excellent stability as a solution, and when the solution is used to modify a wood material, properties such as good durability, hardness, and / or dimensional stability can be imparted to the wood material. DETAILED DESCRIPTION

[0017] Hereinafter, one embodiment of the present invention will be described in more detail.

[0018] Numerical values ​​and ranges described in this specification, unless otherwise indicated by specific terms such as "less than" or "more than / greater than," are understood to include the numerical value as the lower or upper limit. For example, a numerical range of 1 to 10 is interpreted as including both the lower limit "1" and the upper limit "10."

[0019] [Views, etc. as the basis of the present invention]

[0020] In recent years, the depletion of trees, such as tropical broadleaf trees, has been recognized as a problem due to over-harvesting.

[0021] On the other hand, due to the increase in the stock of coniferous trees produced in Japan, there is a demand to develop new uses for coniferous timber produced in Japan and to find its added value. However, when using coniferous timber produced in Japan as a substitute for tropical broadleaf timber, it is necessary to pay proper attention to at least one of the following matters. For example, when using coniferous timber as a substitute for broadleaf timber, it is necessary to improve durability (for example, resistance to wood decay fungi, etc.) and hardness. In addition, there are also problems when using hard and durable broadleaf timber as exterior materials such as wooden outdoor steps. Specifically, wood, especially high-density and hard wood, undergoes large dimensional changes with changes in moisture content, resulting in frequent warping and cracking. Therefore, in order to suppress this, measures such as strong connections with thick bolts are required, and the construction of such measures is very labor-intensive. In addition, such thick bolts are often loosened due to the force that causes the wood to deform. For wood materials used as exterior materials such as wooden outdoor steps, good durability is required, and small dimensional changes with changes in moisture content (i.e., high dimensional stability) are also required. In addition, hardness is also required from the viewpoint of being less likely to be cracked or damaged.

[0022] The technology described in Japanese Patent Application Publication No. 2005-533688 (Patent Document 1) uses acetone or a low-boiling alcohol as a solubilizer. In a furan derivative monomer solution to which such a solubilizer is added, it is difficult to fully suppress the polymerization of the furan derivative, at least during storage at room temperature. If the furan derivative polymerizes and becomes a high molecular weight during storage, i.e., before penetrating into the wood material, it is difficult to more uniformly penetrate the wood material. Therefore, it can be said that such a technology makes it difficult for the furan derivative to fully penetrate the wood material (for example, wood materials made from Japanese conifers such as Japanese cedar and cypress). In addition, even if penetration occurs, it is difficult to achieve satisfactory modification of the wood material.

[0023] In the present invention, there is experience in attempting to solve problems such as the relatively poor durability and hardness of Japanese softwood materials compared to hardwood materials, and the high dimensional stability required as exterior materials, by modifying wood materials into resins using furan derivatives.

[0024] [Production method of the present invention]

[0025] The present invention provides a method for producing a modified wood material. Specifically, the present invention provides a method for producing a modified wood material as a method for modifying a wood material.

[0026] The manufacturing method of the present invention comprises the following steps:

[0027] 1) a step of allowing a furan derivative resin solution containing a furan derivative, an inorganic salt that inhibits polymerization of the furan derivative at room temperature, and an inorganic salt that promotes polymerization of the furan derivative to penetrate into a wood material; and

[0028] 2) A step of polymerizing the furan derivative in the resinified solution of the infiltrated furan derivative by heating it in the wood material.

[0029] In the present invention, the term "furan derivative resinification solution" primarily refers to a liquid used to treat a wood material by polymerizing a furan derivative, thereby incorporating a resin into at least a portion of the wood material. Specifically, "resinification" in this specification essentially refers to the inclusion of a resin component in the wood material, formed by polymerization of the furan derivative in the solution. It should be noted that the "furan derivative resinification solution" will be referred to simply as "solution" in the following descriptions.

[0030] "Room temperature" in the present invention refers to the temperature in an environment where the temperature is not artificially changed by a person skilled in the art such as heating or cooling (e.g., ambient temperature), typically 15-35°C, e.g., 20-30°C or 23-27°C.

[0031] In addition, "heating" in the present invention refers to a method of artificially raising the temperature to appropriately promote the polymerization of the furan derivative, for example, heating the wood material or its surroundings to a temperature condition of 60°C to 160°C, 60°C to 120°C, or 60°C to 100°C, or a temperature condition of 80°C to 160°C or 80°C to 120°C. In addition, "temperature" in the present invention refers to the temperature of the wood material or its surroundings, but for simplicity or convenience, it can also be regarded as the set temperature of the equipment used in production (for example, the temperature set in the heating / heating means of the chamber). In addition, in the present invention, such heating can be continued for 2 to 240 hours, for example, 4 to 168 hours, 10 to 96 hours, 10 to 80 hours, or 10 to 48 hours. In a preferred embodiment, this heating can better promote the polymerization of the furan derivative that has penetrated into the wood material, and at the same time, the wood material wetted by the furan derivative resin solution can be dried.

[0032] The "inorganic salt that inhibits polymerization of furan derivatives at room temperature" in the present invention contributes to stabilization of the furan derivative resinification solution. Therefore, hereinafter, in this specification, the "inorganic salt that inhibits polymerization of furan derivatives at room temperature" may also be referred to as a "stabilizer."

[0033] The "inorganic salt that accelerates the polymerization of furan derivatives" in the present invention acts to accelerate the polymerization of furan derivatives, for example, during the resinification of a woody material accompanied by heating. Therefore, hereinafter, in this specification, the "inorganic salt that accelerates the polymerization of furan derivatives" may also be referred to simply as an "accelerator."

[0034] The term "wood material" in the present invention typically refers to wood. For example, the "wood material" may be raw wood for use in wood products. Specifically, the wood material used in the manufacturing method of the present invention may be wood that has been processed or lumbered from logs to a predetermined shape.

[0035] The furan derivatives used in the production method of the present invention are not particularly limited. For example, they may be those in which a hydrocarbon group (e.g., a hydrocarbon group having 1 to 40, 1 to 30, 1 to 20, 1 to 10, 1 to 8, 1 to 6, 1 to 4, 1 to 3, or 1 to 2 carbon atoms) is directly bonded to the furan skeleton, that is, they may be derivatives substituted with such hydrocarbon groups. For example, furan derivatives include furans substituted with at least one functional group selected from alkyl, formyl, hydroxy, and hydroxyalkyl groups. The number of carbon atoms in each of the alkyl, formyl, hydroxy, and hydroxyalkyl functional groups may be 1 to 20, for example, 1 to 10, 1 to 8, 1 to 6, 1 to 4, 1 to 3, 1 to 2, or 1. Furthermore, the number of substituted functional groups per molecule of the furan derivative may be 1 to 4, for example, 1 to 3, 1 to 2, or 1.

[0036] The furan derivative used in the production method of the present invention may be, for example, at least one polymerizable monomer selected from the group consisting of furfuryl alcohol, furfural, and 5-hydroxymethylfurfural.

[0037] In a solution using an aqueous solvent (particularly a solvent in which water is 100% by weight of the solvent in the solution), these polymerizable monomers are more effectively suppressed by the action of a stabilizer, and are more likely to exist stably. After penetrating into the wood material, the condensation polymerization is further accelerated by the action of an accelerator under heating, which is more preferable for the resinification of the wood material.

[0038] The concentration of the furan derivative in the furan derivative resinized solution can generally be 5 to 50% by weight (excluding 50% by weight), based on the total weight of the furan derivative resinized solution. For example, it can be 5 to 45% by weight, 10 to 45% by weight, 20 to 45% by weight, 20 to 40% by weight, or 25 to 35% by weight. Such a concentration of the furan derivative contributes to better modification of the wood material. For example, modification of the wood material using this solution can easily impart at least one of the following properties to the wood material: better durability (decay resistance), hardness (partial compressive strength), and dimensional stability.

[0039] The furan derivative resinizing solution used in the production method of the present invention contains an "inorganic salt that inhibits polymerization of the furan derivative at room temperature." By incorporating this inorganic salt into the furan derivative resinizing solution, the furan derivative can be stabilized, for example, in a room-temperature solution. This means that even when the solution is stored for a relatively long period of time (e.g., when left at room temperature for a long period of time), unintended polymerization of the furan derivative (e.g., uncontrolled unintended polymerization that could cause turbidity, insolubility, and / or separation in the solution) is easily suppressed, allowing the furan derivative resinizing solution to be used in a more favorable state during the modification process. Furthermore, by suppressing unintended polymerization of the furan derivative, the "inorganic salt that inhibits polymerization of the furan derivative at room temperature" achieves improved quality stability of the solution before penetration into the wood material, thereby effectively suppressing variations in properties imparted to the wood material by the treatment. For example, variations in at least one property selected from durability, hardness (partial compressive strength), and dimensional stability can be effectively suppressed.

[0040] The "inorganic salt that inhibits polymerization of furan derivatives at room temperature" may be, for example, an inorganic carbonate. In addition to or instead of this, the "inorganic salt that inhibits polymerization of furan derivatives at room temperature" may be in the form of, for example, an ammonium salt.

[0041] In a preferred embodiment, the "inorganic salt that inhibits the polymerization of furan derivatives at room temperature" can be at least one inorganic salt selected from ammonium carbonate and ammonium bicarbonate. Specifically, the "inorganic salt that inhibits the polymerization of furan derivatives at room temperature" can be, for example, ammonium carbonate, ammonium bicarbonate, or a combination of ammonium carbonate and ammonium bicarbonate. This is because the unintended polymerization of furan derivatives in the solution can be inhibited at room temperature, and the quality stability of the solution before penetration into the wood material can be better maintained. In addition, during the heating after penetration, an inorganic salt that does not hinder the polymerization of furan derivatives can be formed. In addition, "inhibiting polymerization" here means that the presence of such an inorganic salt will reduce or stop the polymerization reaction rate compared to the case where such an inorganic salt is not present (for example, the case where the polymerizable monomer exists alone).

[0042] An "inorganic salt that inhibits the polymerization of furan derivatives at room temperature" may be an inorganic salt that is alkaline in an aqueous solution (e.g., an aqueous solution at room temperature), or may be an inorganic salt that, for example, makes the furan derivative resin solution alkaline or shifts the pH toward alkalinity (i.e., increases the pH). Furthermore, it is believed that adding a salt such as sodium hydroxide and / or potassium hydroxide to a furan derivative resin solution containing a furan derivative, an inorganic salt that promotes the polymerization of the furan derivative and is neutral to weakly acidic at room temperature, and water, and maintaining the furan derivative resin solution alkaline, can inhibit the polymerization of the furan derivative and maintain the stability of the solution. However, such salts may unintendedly inhibit the polymerization of the furan derivative during subsequent heating. Specifically, they may inhibit the desired polymerization during the modification treatment of wood materials.

[0043] Salts that inhibit polymerization of furan derivatives at room temperature but do not unintentionally inhibit polymerization of furan derivatives after the resinified furan derivative solution has penetrated into the wood material are somewhat limited. For example, salts that decompose and vaporize upon heating and are removed from the reaction system can be used. Typical examples include inorganic salts such as ammonium carbonate and / or ammonium bicarbonate.

[0044] From this perspective, the inorganic salt in the furan derivative resinizing solution used in the production method of the present invention is preferably an inorganic salt that decomposes and vaporizes upon heating. Specifically, the "inorganic salt that inhibits the polymerization of the furan derivative at room temperature" contained in the furan derivative resinizing solution can be an inorganic salt that decomposes upon heating (more specifically, decomposes and vaporizes upon heating) after the furan derivative resinizing solution permeates the wood material. From a similar perspective, the inorganic salt in the furan derivative resinizing solution used in the production method of the present invention preferably excludes sodium hydroxide and potassium hydroxide. In other words, the "inorganic salt that inhibits the polymerization of the furan derivative at room temperature" contained in the furan derivative resinizing solution is preferably an inorganic salt other than sodium hydroxide and potassium hydroxide.

[0045] The content of these inorganic salts can be adjusted appropriately. Adjusting the content facilitates controlling the degree of polymerization of the furan derivatives that occurs after the furan derivative resinification solution permeates the wood material and is heated. Furthermore, it facilitates controlling the location of the wood material cells where the furan resin is formed. For example, increasing the content of the "inorganic salt that inhibits the polymerization of the furan derivative at room temperature" in the solution can easily lower the degree of polymerization of the furan derivative, facilitating the formation of low-molecular-weight furan derivative resins within the cell walls. On the other hand, decreasing the content of the "inorganic salt that inhibits the polymerization of the furan derivative at room temperature" can easily increase the degree of polymerization of the furan derivative, facilitating the formation and accumulation of high-molecular-weight furan resins within the cell cavities.

[0046] Furthermore, as described above, these inorganic salts as stabilizers can further stabilize the state of the furan derivative resinified solution before it penetrates the wood by inhibiting the polymerization of the furan derivative at room temperature. Therefore, when used in modification treatments, they contribute to improved properties of the modified wood material. Furthermore, they can further reduce unevenness in the finish of the modified wood material, facilitating uniformity in the quality of the final product using the modified wood material.

[0047] In the present invention, polymerization in solution can be appropriately considered to more easily impart desired properties to wood materials. However, this is merely one exemplary embodiment. For example, during the initial polymerization of the furan derivative, the molecular weight and reactivity of the resulting polymer (resin) can be controlled, and polymerization of the furan derivative in the furan derivative resinification solution at room temperature can be suppressed. Furthermore, after the furan derivative has penetrated the wood material, heating can be performed to effectively promote the polymerization reaction in the wood material.

[0048] In the furan derivative resinification solution, the concentration of the "inorganic salt that inhibits the polymerization of the furan derivative at room temperature" can be 0.01 mol or less, 0.005 mol or less, 0.004 mol or less, 0.003 mol or less, 0.002 mol or less, or 0.001 mol or less (the lower limit in this case may be a value greater than 0 mol) relative to 1 mol of the furan derivative in the solution. For example, the concentration or amount of the "inorganic salt that inhibits the polymerization of the furan derivative at room temperature" in the furan derivative resinification solution can be 0.0001 to 0.004 mol, for example, 0.0003 to 0.003 mol, 0.0005 to 0.001 mol, 0.0006 to 0.001 mol, or 0.0007 to 0.0009 mol, etc., relative to 1 mol of the furan derivative in the solution. Such a concentration or amount of the "inorganic salt that inhibits the polymerization of the furan derivative at room temperature" contributes to better modification of the wood material. For example, by modifying a wood material using this solution, it is easy to impart at least one favorable property selected from among better durability, hardness (partial compressive strength), and dimensional stability to the wood material.

[0049] The furan derivative resinification solution used in the production method of the present invention may contain, in addition to an "inorganic salt that inhibits polymerization of the furan derivative at room temperature," other types of inorganic salts. For example, it may contain an "inorganic salt that promotes polymerization of the furan derivative." By adding this inorganic salt to the furan derivative resinification solution, polymerization of the furan derivative in the solution can be more effectively promoted during heating for the modification treatment.

[0050] The "inorganic salt that promotes the polymerization of the furan derivative" is preferably an inorganic salt that can promote the polymerization of the furan derivative by heating, particularly by heating in step 2). "Promoting polymerization" as used herein means that the presence of such an inorganic salt increases the polymerization reaction rate compared to a case where the inorganic salt is not present (e.g., a case where the polymerizable monomer is present alone). Such an inorganic salt is acidic in an aqueous solution (e.g., an aqueous solution at room temperature), for example, it can be an inorganic salt that is weakly acidic, for example, it can be an inorganic salt that changes the pH of the furan derivative resin aqueous solution toward the acidic side (i.e., further lowers the pH). For example, the inorganic salt is neutral to weakly acidic as an aqueous solution at room temperature, typically having a pH of 3 to 7 (excluding "7"), for example, it can be pH 4 to 6.5 or pH 5 to 6.

[0051] In the present invention, "pH" refers to a hydrogen ion index, and may be, for example, a pH value measured in accordance with "JIS Z 8802 pH Measurement Method."

[0052] In the production method of the present invention, the "inorganic salt that promotes the polymerization of furan derivatives" can be an inorganic salt composed of "anions of chloride ions and / or sulfate ions" and "cations of ammonium ions and / or magnesium ions and / or hydrogen ions." That is, in addition to the "inorganic salt that inhibits the polymerization of furan derivatives at room temperature" (for example, inorganic salts such as ammonium carbonate and / or ammonium bicarbonate), other types of inorganic salts contained in the solution can be inorganic salts composed of "anions of chloride ions and / or sulfate ions" and "cations of ammonium ions and / or magnesium ions and / or hydrogen ions" (it can be said that the inorganic salt can produce such ions when dissolved in water). If it is such an inorganic salt, it will contribute to better modification of the wood material. For example, by using this solution to modify the wood material, it is easy to impart to the wood material at least one good property selected from better durability, hardness (partial compressive strength), and dimensional stability.

[0053] In a preferred embodiment, the "inorganic salt that promotes polymerization of furan derivatives" may be an inorganic salt having as constituent elements a combination of "either chloride ion or sulfate ion" and "one or two selected from ammonium ion, magnesium ion, and hydrogen ion."

[0054] For example, the "inorganic salt that promotes the polymerization of furan derivatives" may be at least one inorganic salt selected from magnesium chloride, ammonium chloride, ammonium sulfate, ammonium hydrogen sulfate, magnesium sulfate, and magnesium hydrogen sulfate.

[0055] In the furan derivative resinification solution, the concentration or amount of the "inorganic salt promoting polymerization of the furan derivative" can be 0.1 mol or less, 0.09 mol or less, 0.08 mol or less, 0.07 mol or less, 0.06 mol or less, 0.05 mol or less, 0.04 mol or less, 0.03 mol or less, 0.02 mol or less, etc., per 1 mol of the furan derivative in the solution. The lower limit in this case can be a value greater than 0 mol. For example, if the upper limit is 0.1 mol, the concentration or amount of the "inorganic salt that promotes the polymerization of the furan derivative" contained in the furan derivative resinification solution can be 0.001-0.1 mol, 0.002-0.1 mol, 0.003-0.1 mol, 0.004-0.1 mol, 0.005-0.1 mol, 0.006-0.1 mol, 0.007-0.1 mol, 0.008-0.1 mol, 0.009-0.1 mol, etc., per 1 mol of the furan derivative. Such concentrations or amounts of the "inorganic salt that promotes the polymerization of the furan derivative" contribute to better modification of the wood material. For example, modification treatment of the wood material using this solution can easily impart at least one favorable property selected from the group consisting of better durability, hardness (partial compressive strength), and dimensional stability to the wood material.

[0056] The furan derivative resinizing solution used in the present invention can be aqueous. That is, the furan derivative resinizing solution used in the production method of the present invention can be a solution containing the aforementioned furan derivative, an inorganic salt that inhibits polymerization of the furan derivative at room temperature, an inorganic salt that promotes polymerization of the furan derivative, and water as a solvent. In particular, the solvent in the furan derivative resinizing solution can be an aqueous medium. This means that the solvent contained in the solution is substantially solely composed of water. In the present invention, "the solvent in the furan derivative resinizing solution is an aqueous medium" means that the solvent contained in the aforementioned solution is solely composed of water. That is, the furan derivative resinizing solution preferably contains only water as a solvent and does not contain organic solvents / organic solvents such as alcohols (e.g., methanol, ethanol, and / or isopropyl alcohol) and / or acetone. In a more direct preferred embodiment, it can be said that the furan derivative resinizing solution used in the present invention does not contain alcohols (e.g., lower alcohols such as methanol, ethanol, and / or isopropyl alcohol) and / or acetone.

[0057] More specifically, the solvent in the furan derivative resinification solution can be a monomeric solvent consisting solely of water, rather than a mixture. The solvent in the furan derivative resinification solution used in the present invention does not contain an organic solvent and can therefore also be referred to as a non-organic solvent-based solvent (particularly, a non-organic solvent-based solvent is an aqueous medium containing 100% by weight or 100% by volume of water).

[0058] When the solvent of the furan derivative resinization solution is an aqueous solvent consisting solely of water, the effects of the present invention can be more significantly achieved by better modifying the wood material. Without being bound by a particular theory, this is believed to be related to the furan derivative in the furan derivative resinization solution being able to more easily reach the interior of the wood material compared to when the solvent contains alcohol or acetone. Similarly, without being bound by a particular theory, one of the main reasons is that water, used as an aqueous solvent, has a higher polarity and / or a lower molecular weight than alcohols (e.g., lower alcohols) or acetone. Therefore, a 100% aqueous solvent can more easily penetrate the cell walls of the wood than when the solvent contains alcohol or acetone. It should be noted that aqueous solvents can reduce costs when implementing the production method of the present invention and are relatively more advantageous from the perspectives of safety and environmental protection compared to using organic solvents.

[0059] In the present invention, the type of water used as the aqueous solvent (i.e., an aqueous solvent consisting solely of water as a solvent) is not particularly limited, and any commonly known water can be used. The water used as the aqueous solvent may be at least one selected from the group consisting of tap water, purified water, groundwater, river water, rainwater, deionized water, and distilled water, but these are merely examples.

[0060] The wood material to be used in the manufacturing method of the present invention is not particularly limited, and any wood material equivalent to so-called wood can be used. For example, the wood material to be used in the manufacturing method of the present invention includes at least one Japanese-produced conifer selected from Japanese cedar, Japanese cypress, pine, Japanese larch, Japanese fish-scale pine, Sakhalin fir, Japanese hemlock, and Japanese fir. In addition, the wood material includes at least one non-Japanese-produced conifer selected from American southern yellow pine, New Zealand radiata pine, European red pine, Cunninghamia lanceolata, and Douglas fir. Furthermore, in addition to solid wood materials from fast-growing soft broad-leaved trees such as poplar and / or chinaberry, wood materials that have been processed to a certain extent, such as laminated timber, plywood, veneer, plastic plywood and / or fiberboard, as well as the rough boards (roughly sawn boards), veneer, wood chips, wood powder and / or wood fibers (pulp) that constitute them, can also be used. Furthermore, non-wood-based lignocellulosic materials such as bamboo can also be used.

[0061] The wood materials modified by the manufacturing method of the present invention can be used in various indoor and / or outdoor products. For example, the wood materials modified by the manufacturing method of the present invention can be used in furniture, wooden floors, wooden outdoor pedals, exterior walls, blinds, truck bodies, musical instruments, interior materials, exterior materials, etc.

[0062] In a preferred embodiment, the wood material is a coniferous material. In this case, the effect of the present invention can be made more significant. Originally, these wood materials were limited in use due to their low durability and / or hardness (partial compressive strength), but these properties are improved by the manufacturing method of the present invention, and they can be applied to a wider range of uses. The coniferous material can be, for example, cedar and / or cypress. Cedar and / or cypress can be equivalent to Japanese coniferous materials, and thus, it can preferably meet the needs of developing new uses or adding value for Japanese coniferous trees.

[0063] The wood material to be modified (i.e., the wood material before modification or non-modified) can be adjusted to have a moisture content of less than 30 weight % based on the total weight of the wood material, for example, less than 25 weight %, less than 20 weight % or less than 15 weight %, etc. (the lower limit in this case can be a value greater than 0 weight %), but this is only an example.

[0064] As described above, the furan derivative resinizing solution used in the production method of the present invention preferably contains two salts as solute components other than the furan derivative. Specifically, the furan derivative resinizing solution used in step 1) contains a combination of two salts: a "salt that inhibits polymerization of the furan derivative at room temperature" and a "salt that promotes polymerization of the furan derivative." In particular, the furan derivative resinizing solution used in the production method of the present invention is a solution comprising a first inorganic salt that acts as a "stabilizer" and a second inorganic salt that acts as a "promoter." Such a solution contributes to better modification of wood materials. For example, modification treatment of wood materials using this solution facilitates imparting to the wood material at least one property selected from the group consisting of improved durability, hardness (partial compressive strength), and dimensional stability. In a preferred embodiment, the first inorganic salt can be an inorganic salt that inhibits polymerization of the furan derivative at room temperature but decomposes (e.g., an inorganic salt that decomposes and vaporizes) in step 2) upon heating and / or increasing temperature (e.g., increasing temperature to the "initial set temperature" described below).

[0065] Preferably, a solution of a combination of a first inorganic salt (an inorganic salt that inhibits polymerization of a furan derivative at room temperature) and a second inorganic salt (an inorganic salt that promotes polymerization of a furan derivative) can be formed together with the furan derivative and an aqueous solvent (a solvent containing only water and no organic solvent). In particular, a furan derivative resin solution containing the combination of the first and second inorganic salts and a monomer solvent consisting solely of water can achieve a more pronounced modification effect on wood materials, as described above.

[0066] In the production method of the present invention, as step 1), a treatment is performed to allow the furan derivative resin solution to penetrate into the wood material. The method is not particularly limited as long as it facilitates penetration. For example, a chamber capable of housing the wood material and the furan derivative resin solution may be used. Furthermore, in step 1), methods such as allowing the furan derivative resin solution to penetrate into the wood material, spraying or applying the furan derivative resin solution to the wood material, and / or impregnating the wood material with the furan derivative resin solution under reduced pressure and / or pressurized conditions may be used.

[0067] When wood materials such as veneers, wood chips, wood powder, and / or wood fibers (pulp) are thin or small, desired penetration is easily achieved through treatments such as impregnation, coating, and spraying. On the other hand, when wood materials have a cross-sectional dimension exceeding a certain level, such as solid wood or laminated boards, desired penetration is easily achieved through impregnation treatment under reduced pressure and / or pressurized conditions, the so-called reduced pressure / pressurized impregnation method.

[0068] In other words, step 1) can be carried out under reduced pressure less than atmospheric pressure. Such reduced pressure conditions may depend on the shape and / or size of the wood material being modified, and may, for example, be reduced pressure of less than atmospheric pressure up to 10 hPa in a temperature range below room temperature. Such reduced pressure conditions more effectively facilitate penetration of the solution into the wood material. For example, modification of the wood material using the solution can easily impart at least one favorable characteristic selected from the group consisting of improved durability, hardness (partial compressive strength), and dimensional stability to the wood material. The reduced pressure conditions (e.g., the pressure within the chamber) in step 1) may be, for example, 100-10 hPa, 75-10 hPa, 50-10 hPa, 40-10 hPa, or 40-20 hPa. The time for applying the solution to the wood material under reduced pressure is generally 5 minutes to 16 hours, and may be, for example, 30 minutes to 16 hours, 1 hour to 16 hours, 1 hour to 8 hours, 1 hour to 4 hours, or 1 hour to 3 hours.

[0069] In the manufacturing method of the present invention, atmospheric pressure or pressurized conditions may be appropriately employed. For example, a pressurized treatment may be performed after the above-mentioned decompression treatment. Such treatment may employ atmospheric pressure or an ambient pressure higher than atmospheric pressure. For example, a pressure condition of 0.1 to 3 MPa or 0.3 to 2 MPa (e.g., the pressure within the chamber) may be employed. The time period for which the wood material is subjected to such pressure or pressurized conditions may generally be 15 minutes to 72 hours, for example, 30 minutes to 36 hours, or 1 hour to 12 hours.

[0070] In the production method of the present invention, as step 2), a heat treatment is performed to polymerize the furan derivative that has penetrated the wood material. Heating promotes polymerization of the furan derivative in the resinified furan derivative solution in the wood material, and the resulting resin component can modify the wood material.

[0071] The heating in step 2) can be performed by any means as long as the temperature of the wood material infiltrated by the solution is increased. For example, the heating in step 2) can be performed by increasing the temperature of the chamber containing the wood material (e.g., the ambient temperature in the chamber).

[0072] Such heating may be performed at 60 to 160°C. That is, step 2) of the production method of the present invention may be performed under a temperature condition of 60 to 160°C. Alternatively, the heating in step 2) may be performed under a temperature condition of 70 to 180°C, 70 to 170°C, 70 to 160°C, 80 to 160°C, 80 to 150°C, 80 to 140°C, or 80 to 120°C. In addition, the heating in step 2) may be performed at 90 to 140°C, 100 to 140°C, 110 to 140°C, or 120 to 140°C. Such heating conditions contribute to better modification of the wood material. For example, by using the modification treatment of the wood material using the solution, it is easy to impart to the wood material at least one good characteristic selected from better durability, hardness (partial compressive strength), and dimensional stability. Furthermore, the heating temperature in step 2) (eg, the temperature in the chamber) may be 60-250°C, 60-125°C, 60-120°C, or 60-100°C.

[0073] The heat treatment time of the wood material in step 2) can generally be 2 to 240 hours, for example, 4 to 168 hours, 4 to 96 hours, 10 to 96 hours, 10 to 80 hours, or 10 to 48 hours, or 4 to 48 hours, 4 to 30 hours, or 10 to 30 hours, and further, 4 to 24 hours, 4 to 10 hours, or 4 to 8 hours.

[0074] The heating in step 2) can be performed in an air environment, but is not limited thereto. When heating at a relatively high temperature (for example, heating exceeding 200° C.), it can be performed in an inert gas environment such as steam and / or nitrogen.

[0075] During the heating in step 2), the wood material infiltrated with the solution can be dried. For example, the heating in step 2) can polymerize the furan derivatives in the infiltrated furan derivative resinization solution in the wood material, and the wood material can be dried. In other words, for example, in a chamber in which the wood material infiltrated with the furan derivative resinization solution is placed, a heat treatment is performed at a temperature of 60 to 160° C. (e.g., 80 to 160° C., 80 to 150° C., 90 to 150° C., 90 to 120° C., 90 to 110° C., or 100 to 150° C., 110 to 140° C., or 120 to 140° C.) for 2 to 260 hours, or 2 to 240 hours (e.g., 3 to 19 2 hours, 3 to 168 hours, 4 to 168 hours, 4 to 96 hours, 10 to 96 hours, 10 to 80 hours or 10 to 48 hours, or 4 to 48 hours, 4 to 30 hours or 10 to 30 hours, or 4 to 24 hours, 4 to 10 hours, or 4 to 8 hours, etc.), thereby polymerizing the furan derivative that has penetrated into the wood material, and simultaneously or subsequently drying the wood material (the wood material wetted by the penetration of the solution).

[0076] In one preferred embodiment, prior to the heating in step 2), the wood material may be subjected to a heating treatment at a temperature lower than the heating temperature. In other words, during the heating treatment, the "solution-infiltrated wood material" may be temporarily subjected to an "initial set temperature." By applying this "initial set temperature" (i.e., heating at this initial set temperature), at least a portion of the stabilizer in the furan derivative resinized solution can be decomposed in the solution-infiltrated wood material. For example, applying the "initial set temperature" allows at least a portion of the stabilizer in the furan derivative resinized solution to be decomposed while minimizing evaporation of the solution in the solution-infiltrated wood material, thereby contributing to improved modification of the wood material. Specifically, modification of the wood material using the solution facilitates imparting to the wood material at least one of the following properties: improved durability, hardness (partial compressive strength), and dimensional stability.

[0077] In the heating treatment performed at the "initial set temperature", the wood material after being infiltrated with the solution can be heated in, for example, a furan derivative resin solution, so that at least a portion or all of the stabilizer (i.e., an inorganic salt that inhibits the polymerization of the furan derivative at room temperature) in the furan derivative resin solution is decomposed in a manner that minimizes evaporation of the impregnated solution.

[0078] The initial setting temperature may be lower than the heating temperature of step 2). For example, the initial setting temperature may be a temperature that is 80% or lower than the heating temperature of step 2 (i.e., the upper limit of the initial setting temperature may be a temperature that is 80% of the heating temperature), and the lower limit may be a temperature that is 20% of the heating temperature of step 2). In other words, if the initial setting temperature is T i , the heating temperature of step 2) is T ii , then it can be T i =0.2T ii ~0.8T ii , for example, it can be T i =0.3T ii ~0.8T ii , 0.4T ii ~0.75T ii , 0.35T ii ~0.7T ii , or 0.4T ii ~0.7T ii etc. Or it can be T i =0.2T ii ~0.6T ii 、T i =0.3T ii ~0.6T ii 、T i =0.3T ii ~0.5T ii wait.

[0079] The initial set temperature (e.g., the chamber temperature condition set as the initial set temperature) can be 50-100°C, for example, 50-90°C, 50-85°C, 55-85°C, or 55-80°C, but this is merely an example and is not limiting. Furthermore, the duration of treatment of the wood material at the initial set temperature can generally be 1-120 hours, for example, 4-72 hours, 6-60 hours, 10-60 hours, 20-60 hours, 35-60 hours, or 40-60 hours.

[0080] To illustrate one embodiment of the treatment with the initial set temperature, the production method of the present invention may further include, between step 1) and step 2), a step of temporarily heating the wood material after being infiltrated with the furan derivative resinified solution at 50-100°C, 50-90°C, 50-85°C, 55-85°C, 55-80°C, or 50-70°C.

[0081] [Solution of the present invention]

[0082] The solution of the present invention is a furan derivative resin solution suitable for use in the above-mentioned production method. That is, the solution of the present invention is a furan derivative resin solution, which is a solution for modifying wood materials.

[0083] The furan derivative comprises an inorganic salt that inhibits polymerization of the furan derivative at room temperature, and an inorganic salt that promotes polymerization of the furan derivative.

[0084] As described above, the solution preferably contains two salts as solute components other than the furan derivative. Specifically, the furan derivative resinification solution of the present invention contains a combination of two inorganic salts: an "inorganic salt that inhibits polymerization of the furan derivative at room temperature" and an "inorganic salt that promotes polymerization of the furan derivative." This solution is a more effective treatment solution for modifying wood materials. For example, by using the solution of the present invention for modifying wood materials, at least one property selected from the group consisting of improved durability, hardness (partial compressive strength), and dimensional stability can be imparted to the wood material.

[0085] The solution of the present invention preferably contains no organic solvents, for example, no organic solvents / organic solvents such as alcohols (e.g., methanol, ethanol, and / or isopropyl alcohol) and / or acetone. Specifically, as described above, the solvent in the solution of the present invention can be an aqueous medium consisting solely of water. This results in a more effective wood material modification solution, and as described above, can further enhance the modification effect on the wood material. The water concentration of such a furan derivative resinified aqueous solution can be 50% by weight or greater, based on the total solution. The upper limit is not particularly limited, and can be, for example, 80% by weight, 75% by weight, 60% by weight, 55% by weight, etc. (This upper limit may be an upper limit excluding the value itself).

[0086] In a preferred embodiment, the concentration of the "inorganic salt that inhibits polymerization of furan derivatives at room temperature" in the solution of the present invention can be 0.0001 to 0.004 mol per 1 mol of the furan derivative in the solution. Alternatively, the concentration of the "inorganic salt that promotes polymerization of furan derivatives" in the solution of the present invention can be 0.001 to 0.1 mol per 1 mol of the furan derivative in the solution.

[0087] In one preferred embodiment, the content or concentration of the "inorganic salt that inhibits the polymerization of furan derivatives at room temperature" in the solution of the present invention can be less than or lower than the content or concentration of the "inorganic salt that promotes the polymerization of furan derivatives." More specifically, in the furan derivative resinification solution, the molar amount of the "inorganic salt that inhibits the polymerization of furan derivatives at room temperature" relative to 1 mol of the furan derivative in the solution can be less than the molar amount of the "inorganic salt that promotes the polymerization of furan derivatives" relative to 1 mol of the furan derivative in the solution. This relative relationship between the contents of the two inorganic salts facilitates the formation of a more favorable modification treatment solution, and when used in the modification treatment of wood materials, it is easier to impart to the wood materials at least one property selected from the group consisting of improved durability, hardness (partial compressive strength), and dimensional stability.

[0088] The solution of the present invention is preferably characterized by at least high stability. Therefore, even during relatively long-term storage (e.g., when the time required from solution preparation to use, as anticipated in actual production, is required), unintended polymerization of the furan derivative is easily suppressed, allowing the furan derivative resinified solution to be used in a more favorable state during modification. For example, the furan derivative resinified solution of the present invention preferably exhibits no turbidity, insolubility, and / or separation even after 7 days (more preferably 14 days) at room temperature following its preparation (i.e., at least immediately after the 7 or 14 days, the solution exhibits no turbidity, insolubility, and / or separation. For example, the absence of turbidity, insolubility, and / or separation can be determined visually).

[0089] From the perspective of industrial and practical processing and manufacturing, furan derivative resin solutions with high stability are particularly useful. This is because, even when mass-producing modified wood materials, they can effectively suppress variations in the properties of the resulting modified products. For example, it can easily avoid the undesirable situation where large variations between batches in dimensional stability, hardness, durability, and decay resistance, which could hinder marketability, occur.

[0090] The details of the solution of the present invention and other matters such as more specific embodiments have been described in the above-mentioned [Production Method of the Present Invention], and therefore, description thereof will be omitted here to avoid repetition.

[0091] [Modified wood material of the present invention]

[0092] The modified wood material of the present invention is a modified wood material obtained by the above-mentioned production method. That is, the modified wood material of the present invention is a wood material modified by the above-mentioned production method and containing at least a polymerized furan derivative.

[0093] More specifically, the modified wood material of the present invention is a wood material modified using a "furan derivative resin solution containing a furan derivative, an inorganic salt that inhibits polymerization of the furan derivative at room temperature, and an inorganic salt that promotes polymerization of the furan derivative." Therefore, the modified wood material contains at least a furan resin formed by polymerization of the furan derivative and, in a preferred embodiment, may also contain the aforementioned inorganic salts (the first inorganic salt and / or the second inorganic salt) used as raw materials, or substances derived therefrom. The resin formed by polymerization is not limited to polymers and may also at least partially contain oligomers.

[0094] In a preferred embodiment, the modified wood material of the present invention exhibits at least one of the following physical properties.

[0095] (Weight Gain Rate / WPG)

[0096] 20-100%, such as 25-90% or 30-70% weight gain (WPG)

[0097] Weight gain rate (WPG) (%) = [(W t -W0) / W0]×100……Formula (1)

[0098] (W t is the dry weight (g) of the modified material, and W0 is the dry weight (g) of the material before modification (or non-modified wood material)

[0099] (Capacity increase / B)

[0100] 1-14%, for example 2-10% or 4-8% volume increase (B) (%)

[0101] Capacity increase (B) (%) = [(S t -S0) / S0]×100…Formula (2)

[0102] (Where, S t is the cross-sectional area of ​​the completely dry modified material (mm 2 ), S0 is the cross-sectional area of ​​the completely dry material before modification (or non-modified wood material) (mm 2 ))

[0103] (Anti-swelling ability / ASE)

[0104] 50% or more, such as 50-70%, 50-65%, or 50-60% anti-swelling energy (ASE)

[0105] Anti-swelling ability (ASE) (%) = [(S c -S t ) / S c]×100……Formula (3)

[0106] (Where, S t S is the cross-sectional area swelling ratio (%) of the modified material when it absorbs moisture or water under fixed conditions from a completely dry state, c It is the wood cross-sectional area swelling ratio (%) of the material before modification (or non-modified wood material) when it absorbs moisture or water under the same conditions as the modified wood from a completely dry state under fixed conditions.

[0107] Anti-swelling ability (ASE) is an index indicating dimensional stability. If ASE is 50% or more, the modified wood material is suitable for practical use, while if it is less than 50%, it is unsuitable or unacceptable for practical use.

[0108] In this specification, "completely dry" or "completely dry state" refers to the state of a modified or unmodified material after being placed in a thermostat (manufactured by Yamato Scientific Co., Ltd., Model: DN43) set at 105°C until there is no change in weight. Furthermore, the "completely dry weight" refers to the weight of the material when there is no change in weight.

[0109] (Hardness / Partial Compression Strength)

[0110] The partial compressive strength of the wood material measured by the following test method is preferably 1.4 times or more, for example, 1.5 to 3 times or 1.6 to 2.5 times.

[0111] After the modified wood material was humidified, a partial compression strength test was performed using a Shimadzu Corporation Autograph precision universal testing machine according to JIS Z 2101. The head speed was set at 2 mm / min, and the tests were performed with both the plain and straight grain surfaces as the compression surfaces.

[0112] The partial compressive strength value obtained by the JIS Z2101 test is compared with the partial compressive strength value obtained using the same method for unmodified or pre-modified wood materials. Specifically, the ratio of the partial compressive strength of the modified wood material to the unmodified material (or unmodified wood material) is calculated (partial compressive strength value (times) = partial compressive strength of the modified wood material / partial compressive strength of the unmodified or pre-modified wood material).

[0113] It should be noted that, as can be seen from this test method, the partial compressive strength is an indicator of the hardness of the wood material. If the partial compressive strength value (ratio) is 1.4 times or more, the modified wood material is preferably used in practical applications (practical various uses).

[0114] (Durability / Deterioration Resistance / Corrosion Resistance)

[0115] According to JIS K 1571 "Wood Preservatives - Performance Standards and Test Methods", 5.2 Anticorrosive Performance, 5.2.1 Indoor Test, 5.2.1.1 Injection Treatment, the average mass reduction rate is 3% or less

[0116] A more specific method involves inoculating the modified wood material with bacteria (test fungi: Fomitopsis palustris and Trametes versicolor) after the modification treatment. The modified wood material is then placed in an environment at 26±2°C and a relative humidity of 70% or higher for 12 weeks. The average mass loss of the modified wood material is then calculated based on the weight change before and after the treatment.

[0117] When the average mass reduction rate is 3% or less, the modified wood material is preferably suitable for practical use (practical various applications).

[0118] In a preferred embodiment, the modified wood material of the present invention can be a wood material for flooring materials, outdoor pedals (such as wooden outdoor pedals), exterior wall materials, blinds, furniture, truck bodies, wooden fences, traffic barriers, exterior materials and / or musical instruments.

[0119] Because of the aforementioned advantageous properties, the modified wood material of the present invention is not limited to indoor use but is also particularly suitable for use as outdoor timber. Furthermore, when the modified wood material of the present invention is composed of coniferous wood, it can exhibit, for example, durability and / or hardness (partial compressive strength), and / or excellent dimensional stability comparable to tropical broadleaf wood. Therefore, it can be said that the present invention can provide new uses or added value for coniferous trees (e.g., Japanese conifers).

[0120] Other specific matters such as aspects of the modified wood material of the present invention have been directly or indirectly described in the above-mentioned [Production Method of the Present Invention] and [Solution of the Present Invention], and therefore, description thereof will be omitted here to avoid repetition.

[0121] While one embodiment of the present invention has been described above, this is merely a typical example, and the present invention is not limited to these descriptions, and those skilled in the art will readily appreciate that various aspects and modifications are possible.

[0122] For example, the effects described in this specification are merely examples, and the present invention is not necessarily limited to these effects, and may also have additional effects.

[0123] Furthermore, for example, the furan derivative resinification solution described in the present invention is a solution containing a furan derivative, an inorganic salt that inhibits polymerization of the furan derivative at room temperature, and an inorganic salt that promotes polymerization of the furan derivative. However, the presence of components (e.g., trace or extremely trace amounts of components, which can be recognized as trace or extremely trace amounts by those skilled in the art) that are inevitably or accidentally mixed into the solution during preparation, storage, and / or use is acceptable.

[0124] It should be noted that the present invention described above includes the following aspects for confirmation.

[0125] A first embodiment: A modification method for a wood material, comprising the following steps: 1) allowing a furan derivative resin solution containing a furan derivative, an inorganic salt that inhibits polymerization of the furan derivative at room temperature, and an inorganic salt that promotes polymerization of the furan derivative to penetrate into the wood material; and 2) allowing the penetrated furan derivative to solidify and dry in the wood material by heating.

[0126] A second aspect: A modification method according to the first aspect, wherein the inorganic salt that inhibits polymerization of the furan derivative is at least one selected from ammonium carbonate and ammonium bicarbonate.

[0127] A third embodiment: A modification method, characterized in that, in the first or second embodiment, the inorganic salt that promotes polymerization of the furan derivative is an inorganic salt composed of "anions of chloride ions and / or sulfate ions" and "cations of ammonium ions and / or magnesium ions and / or hydrogen ions."

[0128] A fourth aspect: A modification method according to any one of the first to third aspects, wherein the wood material is a coniferous tree.

[0129] Fifth embodiment: A furan derivative resinified solution for use in a method for modifying wood materials, comprising a furan derivative, an inorganic salt that inhibits polymerization of the furan derivative at room temperature, and an inorganic salt that is neutral to weakly acidic at room temperature and promotes polymerization of the furan derivative.

[0130] A sixth aspect: A wooden material modified by any one of the first to fourth aspects or modified using the furan derivative resinified solution of the fifth aspect, and containing at least a polymerized furan derivative.

[0131] Example

[0132] Various verification experiments were carried out for the present invention.

[0133] In order to confirm the stability of the furan derivative resinification solution and the wood material modification effect of the solution, various components were selected. The modification effect of the wood material resinification was evaluated using the following parameters.

[0134] Dimensional stability (anti-swelling ability)

[0135] Hardness (partial compressive strength)

[0136] Durability (decay resistance)

[0137] Study on the combination of stabilizers and accelerators in furan derivative resinification solutions

[0138] As Examples 1 to 9 and Comparative Examples 1 to 4, wood materials were resinified using the following furan derivative resinification solutions, and the modification effects were evaluated.

[0139] Furan derivative resin solution

[0140] · Furan derivatives :Furfuryl alcohol (FA)

[0141] · stabilizer (Polymerization-inhibiting inorganic salts): ammonium carbonate, ammonium bicarbonate, sodium hydroxide, potassium hydroxide

[0142] · Accelerator (Polymerization-promoting inorganic salts and organic acids): ammonium chloride, magnesium chloride, magnesium sulfate, ammonium sulfate, ammonium bisulfate, magnesium bisulfate, citric acid, maleic anhydride

[0143] · solvent : Water solvent (the solvent of the solution is water 100% by weight)

[0144] Wood material: Japanese cedar and cypress

[0145] Specifically, a furan derivative resinification solution was prepared by adding 0.0008 mol of a stabilizer and 0.01 mol of an accelerator per 1 mol of furfuryl alcohol to a furfuryl alcohol aqueous solution having a FA concentration of 30% by weight (based on the total solution). The solvent used in this solution was an aqueous solvent consisting solely of water.

[0146] Using a chamber (a chamber equipped with heating and pressure reduction / pressure increase mechanisms) capable of loading a furan derivative resinification solution and a wood material, attempts were made to perform a modification treatment on the wood material.

[0147] Specifically, a cedar or cypress wood with a cross-section of 30 mm square in the tangential and radial directions and 6 mm in the fiber direction (i.e., a size of 30 mm × 30 mm × 6 mm) was immersed in the prepared furan derivative resin solution and injected at a reduced pressure of 30 hPa for 2 hours.

[0148] The treated cedar or cypress wood was then heated at an initial set temperature of 60°C for 48 hours and then at 130°C for 24 hours to polymerize the infiltrated furan derivative in the wood material, thereby attempting to modify the wood material.

[0149] Evaluation items of modification effect

[0150] Dimensional stability (ASE): The modified wood material was dried to a completely dry state with no weight change using a thermostat (manufactured by Yamato Scientific Co., Ltd., Model: DN43) set at 105°C. The dimensions of the modified wood material (cedar or cypress) in this completely dry state were measured in the tangential and radial directions to determine the cross-sectional area of ​​the wood.

[0151] Next, the completely dry modified wood material is immersed in deionized water and subjected to reduced pressure injection (at a temperature below 30 hPa for 2 hours). After standing in the water for a predetermined period of time (one day and night, i.e., a full day of 24 hours), the modified wood material is removed and its dimensions are measured in the same manner in the saturated state to determine the area of ​​the wood cross section. Thus, the area swelling ratio (%) of the wood cross section accompanying the treatment from the completely dry state to the saturated state is determined. This is compared with an untreated wood material that has not undergone the modification treatment, and the ASE (anti-swelling ability) (%) is determined according to the above formula (3).

[0152] ○:More than 50%

[0153] ×: less than 50%

[0154] Hardness (partial compressive strength): After conditioning the resinized test specimens at 20°C and 60% relative humidity for one month, partial compressive strength tests were conducted using a Shimadzu Corporation precision universal testing machine (Autograph) in accordance with JIS Z2101. The head speed was set at 2 mm / min, and the tests were conducted with both the plain and straight grain surfaces as the compression surfaces to determine the partial compressive strength. This was compared with an untreated wood material (non-resinized / non-modified test specimen) that had not undergone the modification treatment to determine the partial compressive strength ratio (times). Note that the evaluation of "partial compressive strength" used wood materials measuring 23 mm x 23 mm x 90 mm. More specifically, for the modified test specimens, a wood material measuring 23 mm x 23 mm x 400 mm was modified, cut to 23 mm x 23 mm x 90 mm after the modification treatment, and the aforementioned test was conducted to determine the partial compressive strength value.

[0155] ○: The partial compressive strength of the resinized test piece is 1.4 times or more that of the non-resinized test piece

[0156] ×: The partial compressive strength of the test piece is less than 1.4 times that of the untreated test piece

[0157] · Durability (Decayability and Corrosion Resistance):

[0158] According to JIS K 1571 "Wood preservatives - Performance standards and test methods", 5.2 Anticorrosive performance, 5.2.1 Indoor test, 5.2.1.1 Injection treatment, the decay resistance of the test body was evaluated. Specifically, after the modified test body was inoculated with bacteria, the test body was placed in an environment of 26±2°C and a relative humidity of 70% or more for 12 weeks. Then, the average mass reduction rate was calculated from the weight change of the modified test body. As test bacteria, brown rot fungi and Coriolus versicolor were used respectively (the same treatment as above was carried out on the non-modified Japanese cedar sapwood test body that was not subjected to the modification treatment, thereby confirming that these test bacteria have the desired activity. Specifically, by carrying out the same treatment as above, in the case of brown rot fungi, the non-modified test body showed an average mass reduction rate of more than 30%, and in the case of Coriolus versicolor, the non-modified test body showed an average mass reduction rate of more than 15%, confirming that these test bacteria have the desired activity).

[0159] Furthermore, the evaluation of "durability (decay resistance, decay resistance)" used wood materials measuring 20 mm x 20 mm x 10 mm. More specifically, for the modified test specimens, wood materials measuring 20 mm x 20 mm x 155 mm were modified and then cut into 20 mm x 20 mm x 10 mm pieces. The above test was then conducted to fully understand durability.

[0160] ○: Average mass reduction rate of the modified test piece is 3% or less

[0161] ×: The average mass reduction rate of the modified test piece exceeds 3%

[0162] · Solution stability :

[0163] The furan derivative resinified solution was evaluated for its solution stability.

[0164] ○: After preparation, the resin solution was allowed to stand at room temperature and atmospheric pressure, and the solution did not become insoluble or separate for more than one week after preparation (at least immediately after one week).

[0165] ×: After preparation, the resinified solution was left to stand at room temperature and atmospheric pressure, but the solution became insoluble and separated within less than one week after preparation.

[0166] · Comprehensive evaluation

[0167] ○: No ×

[0168] ×: There are more than one ×

[0169] The results are shown in Table 1.

[0170]

[0171] From the results in Table 1, the following points can be fully understood.

[0172] As a combination of a stabilizer and an accelerator, a combination of an inorganic salt such as ammonium carbonate or ammonium bicarbonate (an inorganic salt that inhibits polymerization of furan derivatives at room temperature) and an inorganic salt composed of "anions of chloride ions and / or sulfate ions" and "cations of ammonium ions and / or magnesium ions and / or hydrogen ions" (an inorganic salt that promotes polymerization of furan derivatives) has shown good test results.

[0173] Although sodium hydroxide or potassium hydroxide can maintain the stability of the solution, when the resinified solution is applied to wood materials, it will unexpectedly inhibit the polymerization of the furan derivative, and the desired effect cannot be achieved.

[0174] When organic acids such as citric acid or maleic anhydride are used as accelerators, the aqueous solution becomes insoluble and separates within a short period of time. This prevents the desired effect from being achieved when the resinified solution is applied to wood materials.

[0175] When the wood species was changed from Japanese cedar to cypress, the same good test results were shown overall.

[0176] (Additional research on wood materials)

[0177] The resinification of the wood material was carried out under the same conditions as in Example 1, except that Scots pine and radiata pine were used as the wood material instead of Japanese cedar and cypress, respectively.

[0178] As a result, such coniferous wood also obtained the same good comprehensive evaluation test results as the above examples. Therefore, it can be seen that by successfully resinifying coniferous wood, it is possible to obtain durability and hardness equivalent to tropical broadleaf wood.

[0179] (Additional studies on stabilizer concentration)

[0180] The resinification of the wood material was carried out under the same conditions as in Example 1 except that the stabilizer concentration was varied between 0.0001 and 0.004 mol per mol of furfuryl alcohol. Specifically, the stabilizer concentrations were 0.0001 mol, 0.001 mol, and 0.004 mol per mol of furfuryl alcohol.

[0181] As a result, when the stabilizer concentration was 0.0001 to 0.004 mol per 1 mol of furfuryl alcohol, the same test results with good overall evaluation as those in the above-mentioned Examples were obtained.

[0182] (Additional studies on accelerator concentration)

[0183] The resinification of the wood material was carried out under the same conditions as in Example 1 except that the accelerator concentration was varied between 0.001 and 0.1 mol per mol of furfuryl alcohol. Specifically, the accelerator concentrations were 0.001 mol, 0.005 mol, and 0.1 mol per mol of furfuryl alcohol.

[0184] As a result, when the accelerator concentration was 0.001 to 0.1 mol per mol of furfuryl alcohol, the same test results with good overall evaluation as those in the above examples were obtained.

[0185] (Additional study on initial set temperature)

[0186] The resinification of the wood material was carried out under the same conditions as in Example 1 except that the initial setting temperature was varied between 50°C and 90°C. Specifically, the initial setting temperature was 50°C, 70°C, 80°C, and 90°C.

[0187] As a result, when the initial set temperature is set to 50°C to 90°C (ie, T i = About 0.4T ii ~about 0.7T ii ), the same good comprehensive evaluation test results as in the above embodiment can be obtained.

[0188] (Additional study on heating temperature)

[0189] The resinification of the wood material was carried out under the same conditions as in Example 1 except that the heating temperature during polymerization was varied between 80°C and 160°C. Specifically, the heating temperatures were 80°C, 100°C, and 160°C.

[0190] As a result, when the heating temperature during polymerization was set to 80 to 160° C., good test results in overall evaluation similar to those in the above-mentioned Examples were obtained.

[0191] (Additional study on the presence of accelerators)

[0192] The resinification of the wood material was carried out under the same conditions as in Example 1, except that no accelerator was used in the solution.

[0193] As a result, compared with Examples 1 to 9, polymerization of the furan derivative in the solution that permeated into the wood material was relatively not promoted, and desired resinification could not be achieved.

[0194] (Additional studies on solvents)

[0195] Resinification of the wood material was performed under the same conditions as in Example 1, except that an organic solvent was additionally used as the solvent in place of the 100% aqueous solvent of water. Specifically, resinification of the wood material was performed under the same conditions as in Example 1, except that a water-acetone mixed solvent (acetone content: 50% by weight relative to the total resinification solution) and a water-ethanol mixed solvent (ethanol content: 50% by weight relative to the total resinification solution) were used, respectively.

[0196] As a result, the desired resinification cannot be achieved due to the presence of an organic solvent. Specifically, due to the presence of an organic solvent such as acetone and / or ethanol, the resinification solution cannot fully penetrate into the wood material, and the wood material cannot be modified satisfactorily.

[0197] In Table 2 below, specific results of dimensional stability (ASE) are particularly shown.

[0198] [Table 2]

[0199] organic solvents Dimensional stability (ASE) / % acetone 35.5 ethanol 30.4

[0200] As can be seen from Table 2, if the solvent contains acetone and ethanol, the ASE is less than 50%.

[0201] As mentioned above, the desired resinification cannot be achieved if an organic solvent is included as a solvent. While not being bound by a particular theory, it is speculated that this is because organic solvents have lower polarity and higher molecular weight than water, preventing furfuryl alcohol from penetrating the cell walls of the wood material. Alternatively, and also without being bound by a particular theory, it is speculated that furfuryl alcohol evaporates along with the organic solvent at the initial set temperature and / or the heating temperature during polymerization.

[0202] The above results indicate that, according to the present invention, the furan derivative resinification solution containing a combination of a furan derivative and two specific inorganic salts can provide improved solution stability. When used for furan resinification of wood materials such as coniferous wood, the furan derivative resinification solution can impart excellent durability, hardness, or dimensional stability to the wood materials.

[0203] [Cross-reference to related applications]

[0204] This case is based on and claims the benefit of priority from Japanese Patent Application No. 2020-128665 filed on July 29, 2020, the entire contents of which are incorporated herein by reference.

[0205] Industrial applicability

[0206] The technology of the present invention can be used to modify wood materials. For example, by modifying wood materials, they can be made suitable for outdoor use. Therefore, the present invention is not only suitable for interior materials such as furniture and wooden flooring, but also for exterior materials such as wooden outdoor stepping boards, particularly for outdoor use.

Claims

1. A method for producing a modified wood material, comprising the following steps: 1) a step of allowing a furan derivative resin solution containing a furan derivative, an inorganic salt that inhibits polymerization of the furan derivative at room temperature, and an inorganic salt that promotes polymerization of the furan derivative to penetrate into a wood material; and 2) a step of polymerizing the furan derivative in the impregnated furan derivative resin solution in the wood material by heating; The inorganic salt that inhibits the polymerization of furan derivatives at room temperature is at least one selected from ammonium carbonate and ammonium bicarbonate, The inorganic salt that promotes the polymerization of furan derivatives is an inorganic salt composed of anions of chloride ions and / or sulfate ions and cations of ammonium ions and / or magnesium ions. The concentration of the inorganic salt that inhibits polymerization of the furan derivative at room temperature is 0.0001 to 0.004 mol relative to 1 mol of the furan derivative, and the concentration of the inorganic salt that promotes polymerization of the furan derivative is 0.001 to 0.1 mol relative to 1 mol of the furan derivative. The furan derivative is furfuryl alcohol, The furan derivative resin solution has a furan derivative concentration of 5% by weight or more and less than 50% by weight based on the entire furan derivative resin solution. The solvent in the furan derivative resinification solution is an aqueous medium.

2. The manufacturing method according to claim 1, wherein The inorganic salt that inhibits the polymerization of furan derivatives at room temperature is an inorganic salt that decomposes and vaporizes by heating.

3. The manufacturing method according to claim 1 or 2, wherein: Step 1) is carried out under reduced pressure less than atmospheric pressure.

4. The manufacturing method according to claim 1 or 2, wherein: The heating in step 2) is performed at 80 to 160°C.

5. The manufacturing method according to claim 1 or 2, wherein: The wood material is coniferous wood.

6. The manufacturing method according to claim 1 or 2, wherein: The wood material is Japanese cedar or cypress.

7. A furan derivative resin solution for modifying wood materials. The furan derivative resinification solution contains a furan derivative, an inorganic salt that inhibits polymerization of the furan derivative at room temperature, and an inorganic salt that promotes polymerization of the furan derivative. The inorganic salt that inhibits the polymerization of furan derivatives at room temperature is at least one selected from ammonium carbonate and ammonium bicarbonate, The inorganic salt that promotes the polymerization of furan derivatives is an inorganic salt composed of anions of chloride ions and / or sulfate ions and cations of ammonium ions and / or magnesium ions. The concentration of the inorganic salt that inhibits polymerization of the furan derivative at room temperature is 0.0001 to 0.004 mol relative to 1 mol of the furan derivative, and the concentration of the inorganic salt that promotes polymerization of the furan derivative is 0.001 to 0.1 mol relative to 1 mol of the furan derivative. The furan derivative is furfuryl alcohol, The furan derivative resin solution has a furan derivative concentration of 5% by weight or more and less than 50% by weight based on the entire furan derivative resin solution. The solvent in the furan derivative resinification solution is an aqueous medium.

8. A modified wood material, which is a wood material modified by the production method according to claim 1 or 2, and contains at least a polymerized furan derivative.

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