Method for manufacturing modified wood material, and modified wood material

Abstract

To provide a method for producing modified wood material with high dimensional stability. [Solution] A method for producing modified wood material, comprising: 1) impregnating an untreated wood material with at least one acid selected from citric acid, malic acid, and glutaric acid, and glycerin to obtain a drug-impregnated wood material; and 2) heating the drug-impregnated wood material obtained in step 1.

Description

[Technical Field]

[0001] This disclosure relates to a method for modifying wood materials, that is, a method for manufacturing modified wood materials. Furthermore, this disclosure relates to modified wood materials manufactured by the manufacturing method of this disclosure. [Background technology]

[0002] Various methods are known for modifying wood materials. For example, it is known that wood materials can be treated with polyhydric alcohols and polyhydric carboxylic acids to improve their dimensional stability, decay resistance, and other properties. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 7-32313 [Overview of the project] [Problems that the invention aims to solve]

[0004] Wood-based materials are used in exterior components such as wood decks, exterior walls, louvers, and wood fences, and in these applications in particular, high durability and dimensional stability are required. The purpose of this disclosure is to provide a method for producing modified wood-based materials that have high dimensional stability. [Means for solving the problem]

[0005] This disclosure provides the following aspects: (Item 1) A method for producing modified wood material, 1) A step of impregnating an untreated wood material with at least one acid selected from citric acid, malic acid, and glutaric acid, and glycerin to obtain a drug-impregnated wood material, 2) The process of heating the chemical-impregnated wood material obtained in step 1 A manufacturing method that includes this. (Item 2) The manufacturing method according to Item 1, wherein the molar ratio of glycerin to the total number of carboxyl groups of the acid is 0.1 to 0.50. (Clause 3) The manufacturing method according to claim 1, wherein the acid is citric acid, and the molar ratio of glycerin to citric acid is 0.5 to 1.4. (Item 4) The manufacturing method according to any one of Items 1 to 3, wherein step 1 is a step of impregnating an untreated wood material with an aqueous solution containing glycerin and the acid. (Item 5) The manufacturing method according to Item 4, wherein the total concentration of the acid and glycerin in the aqueous solution is 10% by mass or more. (Item 6) The manufacturing method according to Item 4, wherein the total concentration of the acid and glycerin in the aqueous solution is 40% by mass or less. (Item 7) The method of production according to any one of items 1 to 6, wherein the acid is citric acid. (Item 8) The manufacturing method according to any one of items 1 to 7, wherein the heating temperature in step 2 is 130 to 180°C. (Item 9) The manufacturing method according to any one of items 1 to 8, wherein the wood material is coniferous wood. (Item 10) The method of manufacture according to any one of items 1 to 9, wherein the wood material is cedar or cypress. (Item 11) The manufacturing method according to any one of items 1 to 10, wherein in step 1, the material is further impregnated with a polyol. (Item 12) The method for manufacturing according to item 11, wherein the polyol is PEG200 or PEG400. (Item 13) Modified wood material manufactured by the manufacturing method described in any one of items 1 to 12. (Item 14) Modified wood material comprising at least one acid selected from citric acid, malic acid, and glutaric acid, and glycerin. (Section 15) Modified wood materials as described in Section 13 or 14, used for flooring, decking, exterior walling, louvers, furniture, wooden fences, guardrails, exterior materials and / or musical instruments. [Effects of the Invention]

[0006] According to this disclosure, a method for producing a modified wood material having high dimensional stability can be provided. [Modes for carrying out the invention]

[0007] The manufacturing method related to this disclosure will be described below.

[0008] The manufacturing method disclosed herein modifies wood-based materials and provides modified wood-based materials. In other words, the manufacturing method of modified wood-based materials according to this disclosure can also be called a method for modifying wood-based materials. According to the manufacturing method disclosed herein, the dimensional stability of wood-based materials can be improved. Furthermore, according to the manufacturing method disclosed herein, the termite resistance and decay resistance of wood-based materials can be improved.

[0009] In recent years, research has been progressing on the effective utilization of wood materials, exploring further applications. For example, the use of wood materials as exterior components such as wood decks, exterior walls, louvers, and wood fences has attracted attention. However, since these applications are mainly carried out in harsh outdoor environments, dimensional stability and durability are required. In particular, softwood is less durable than hardwood (hereinafter simply referred to as "hardwood") which has traditionally been used for exteriors such as wood decks, so when using softwood as a substitute for hardwood, it is necessary to improve its durability. Also, while hardwood is used because of its high durability and hardness, it has issues with dimensional stability. This is also true for softwood; when used in harsh outdoor environments, warping and / or cracking often occur, shortening the service life more than expected, so improving dimensional stability is important.

[0010] This disclosure addresses the problem of softwood being relatively less durable than, for example, hardwood, and the need to impart high dimensional stability and prevent cracking and warping, by modifying the wood material with at least one acid selected from citric acid, malic acid, and glutaric acid, and glycerin.

[0011] These effects are not particularly bound by theory, but are thought to be due to the reaction of an acid and glycerin in the wood material to resinify in the wood material, or the reaction of an acid and a hydroxyl group in the wood components.

[0012] [Method for producing modified wood material] The method for producing a modified wood material of the present disclosure is 1) A step of impregnating at least one acid selected from citric acid, malic acid, and glutaric acid, and glycerin into an untreated wood material to obtain a medicament-impregnated wood material; 2) A step of heating the medicament-impregnated wood material obtained in step 1 and includes.

[0013] (Step 1) In step 1, at least one acid selected from citric acid, malic acid, and glutaric acid, and glycerin are impregnated into an untreated wood material to obtain a medicament-impregnated wood material. In the present specification, the above acid and glycerin may be collectively referred to as a medicament.

[0014] The above acid may be one kind or a mixture of two or more kinds, but is preferably one kind. The above acid is preferably citric acid. By treating the untreated wood material by using these acids in combination with glycerin, a modified wood material having high dimensional stability can be obtained.

[0015] The method for impregnating the above acid and glycerin into the wood material is not particularly limited, but it is preferable to treat the untreated wood material with a solution containing the acid and glycerin.

[0016] The above treatment is performed by immersing the untreated wood material in a solution containing the medicament, or spraying or applying a solution containing the medicament to the untreated wood material. Preferably, the above treatment is performed by immersing the untreated wood material in a solution containing the medicament. The above immersion treatment is preferably performed by immersing the untreated wood material in a solution containing the medicament under reduced pressure and / or increased pressure, so-called reduced pressure / increased pressure impregnation method.

[0017] The above reduced pressure conditions may depend on the shape and / or size of the untreated wood material subjected to the modification treatment, but may be, for example, below atmospheric pressure, such as 1-100 hPa, 10-80 hPa, 20-60 hPa, or 30-50 hPa. Under such reduced pressure conditions, the penetration of the solution into the untreated wood material is further promoted.

[0018] The above pressurization conditions may depend on the shape and / or size of the untreated wood material subjected to the modification process, but for example, they may be higher than atmospheric pressure, such as 0.1 to 3 MPa, 0.3 to 2 MPa, or 0.3 to 1.5 MPa.

[0019] The temperature of the solution used when immersing untreated wood material in the solution containing the above-mentioned chemicals may be, for example, room temperature, preferably 20-30°C or 23-27°C.

[0020] In this disclosure, "room temperature" means the temperature of an environment in which a person skilled in the art does not artificially change the temperature by heating, cooling, or other means (e.g., ambient temperature), and is typically 15 to 35°C, for example 20 to 30°C or 23 to 27°C, and may specifically be 25°C.

[0021] The immersion time of the untreated wood material in the solution may depend on the shape and / or size of the untreated wood material being modified, but may be, for example, 5 minutes to 16 hours, 30 minutes to 16 hours, 1 to 16 hours, 1 to 8 hours, 1 to 4 hours, or 1 to 3 hours.

[0022] An example of the above-mentioned vacuum / pressure impregnation method involves sequentially performing vacuum, depressurization, pressurization, and depressurization. Vacuuming can be performed, for example, at 30-50 hPa for 1-2 hours. Pressurization may be performed in stages, for example, at 0.3 MPa for 0.5-1 hour, 0.5 MPa for 0.5-1 hour, 0.8 MPa for 1-4 hours, 1.0 MPa for 1-4 hours, 1.3 MPa for 1-4 hours, and 1.5 MPa for 1-24 hours. These conditions can be appropriately changed depending on the shape and type of the untreated wood material. For example, the above pressurization protocol may be stopped midway.

[0023] The solution containing the acid and glycerin is preferably an aqueous solution. Using an aqueous solution makes preparation easier and is environmentally friendly.

[0024] In this invention, there are no particular restrictions on the type of water used as the solvent for the aqueous solution; any water generally recognized as water can be used. For illustrative purposes only, the water may be at least one selected from the group consisting of tap water, purified water, groundwater, river water, rainwater, deionized water, and distilled water.

[0025] In a preferred embodiment, the solution containing the above-mentioned agent does not contain an organic solvent.

[0026] The total concentration of acid and glycerin in the above solution is preferably 10% by mass or more, more preferably 15% by mass or more, and even more preferably 20% by mass or more, for example, 25% by mass or more. By setting the total concentration of acid and glycerin in the above solution within the above range, the yield of the drug is improved.

[0027] The total concentration of acid and glycerin in the above solution is preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 35% by mass or less. By setting the total concentration of acid and glycerin in the above solution within the above range, the AES of the wood specimen treated with the chemical is improved. Dimensional stability may also be improved.

[0028] The total concentration of acid and glycerin in the above solution is preferably 10-50% by mass, more preferably 15-40% by mass, even more preferably 20-50% by mass, and even more preferably 25-40% by mass, for example, 10-40% by mass, 15-35% by mass, or 15-30% by mass. By setting the total concentration of acid and glycerin in the above solution within the above range, the yield of the agent from the treated wood material can be improved, and dimensional stability can also be improved.

[0029] The molar ratio of glycerin to the total number of carboxyl groups in the acid (glycerin / carboxyl groups) is preferably 0.1 to 0.5, more preferably 0.15 to 0.4, and even more preferably 0.2 to 0.4. The modified wood material may lose weight when subjected to three repetitions of the following operation: water impregnation under reduced pressure, followed by 24 hours of immersion in water and 24 hours of air drying at 105°C (hereinafter referred to as the "leaching operation"). This weight loss is thought to be due to the leaching of unreacted glycerin and / or acid after the reaction. By setting the molar ratio of glycerin to the total number of carboxyl groups in the acid within the above range, the reaction between the acid and glycerin proceeds quantitatively, reducing the weight loss rate of the modified wood material, i.e., reducing the amount of unreacted material.

[0030] Preferably, when the acid is citric acid, the molar ratio of glycerin to citric acid (glycerin / citric acid) is preferably 0.5 to 1.4, more preferably 0.7 to 1.2, even more preferably 0.8 to 1.2, even more preferably 1.0 to 1.2, particularly preferably 1.05 to 1.15, and specifically about 1.1.

[0031] Preferably, when the acid is malic acid or glutaric acid, the molar ratio of glycerin to malic acid or glutaric acid (glycerin / malic acid or glutaric acid) is preferably 0.3 to 1.0, more preferably 0.4 to 0.8, even more preferably 0.5 to 0.7, and specifically about 0.67.

[0032] In one embodiment, in step 1, the material may be further impregnated with a polyol.

[0033] The polyol mentioned above is not particularly limited, but could be, for example, polyethylene glycol, such as PEG200 or PEG400.

[0034] (Process 2) In step 2, the chemical-impregnated wood material obtained in step 1 is heated. Heating causes the glycerin impregnated in the chemical-impregnated wood material to react with the acid. In addition, some of the acid reacts with the hydroxyl groups in the wood components. As a result, the wood material is modified, and so-called resin compounding is thought to proceed.

[0035] The heating in step 2 is not particularly limited as long as it is a method that can raise the temperature of the chemical-impregnated wood material. For example, heating in step 2 may be performed by raising the temperature of the chamber in which the chemical-impregnated wood material is placed (for example, the ambient temperature inside the chamber).

[0036] The heating temperature may preferably be 100-180°C, more preferably 130-180°C, even more preferably 140-180°C, and even more preferably 150-170°C. Increasing the heating temperature improves the reaction rate of the drug and shortens the processing time. It also reduces the rate of drug leakage. On the other hand, lowering the heating temperature improves the yield of the drug. This is thought to be because the decomposition or evaporation of the drug is suppressed.

[0037] The heating time in step 2 can typically be 2 to 240 hours, and may be, for example, 4 to 168 hours, 4 to 96 hours, 10 to 96 hours, 10 to 80 hours, 10 to 48 hours, 4 to 48 hours, 4 to 30 hours, 10 to 30 hours, 4 to 24 hours, 4 to 10 hours, or 4 to 8 hours.

[0038] The heating in step 2 may, but is not limited to, an air atmosphere. For example, heating to relatively high temperatures (e.g., heating above 200°C) may be carried out in an inert gas atmosphere such as water vapor and / or nitrogen gas.

[0039] The wood material may be dried during or after heating in step 2. For example, the wood material may be dried while the impregnated glycerin and acid react within the wood material during heating in step 2.

[0040] The wood-based materials to which the manufacturing methods of this disclosure apply are not particularly limited, and any material equivalent to so-called wood is acceptable. For example, the wood-based materials to which the manufacturing methods of this disclosure apply are coniferous woods, and include at least one type of coniferous wood selected from the group consisting of Japanese cedar, cypress, pine, larch, Yezo spruce, Sakhalin fir, hemlock, fir, Southern yellow pine, radiata pine, Scots pine, Cunninghamia lanceolata, and Douglas fir. Furthermore, the wood-based materials to which the manufacturing methods of this disclosure apply may include solid wood of fast-growing but soft hardwoods such as poplar and / or chinaberry, as well as wood-based materials that have undergone some degree of processing, such as laminated wood, plywood, veneer, particleboard and / or fiberboard, and non-woody lignocellulose materials such as laminas (sawn boards), veneers, wood chips, wood powder and / or wood fibers (pulp) that constitute them, and bamboo.

[0041] In a preferred embodiment, the wood material is coniferous wood. In this case, the effects of the present invention may be more pronounced. Originally, these wood materials have limited uses due to their low durability and / or hardness (partial compressive strength), but the manufacturing method of the present disclosure improves their properties, making them applicable to a wider range of uses.

[0042] In one embodiment, the untreated wood material subjected to the modification treatment may be wood material whose moisture content has been adjusted to 30% by weight or less, for example, 25% by weight or less, 20% by weight or less, or 15% by weight or less, based on the total weight of the wood material (in this case, the lower limit may be a value of 0% by weight or more).

[0043] The modified wood materials produced by the manufacturing method of the present disclosure can be used in a variety of indoor and / or outdoor applications, preferably for outdoor applications. For example, the modified wood materials produced by the manufacturing method of the present disclosure can be used in flooring, decking, exterior wall materials, louvers, furniture, wooden fences, guardrails, exterior materials and / or musical instruments.

[0044] [Modified wood materials] This disclosure provides a modified wood material produced by the method for producing the modified wood material of this disclosure. Such a modified wood material comprises a reaction product with at least one acid selected from citric acid, malic acid, and glutaric acid, and glycerin.

[0045] The modified wood material of the present invention may have at least one of the following physical properties. (Pharmaceutical yield) Drug yield of 50-100%, for example, 60-90%, 70-90%, or 70-80% Chemical yield (%) = {(Total dry mass of modified wood material - Total dry mass of untreated wood material) / (Mass of chemical solution impregnated in chemical-impregnated wood material × Chemical concentration (mass %) / 100)} × 100 (Drug loss rate) Drug loss rate of 10% or less, for example, 0.1-5% or 0.5-3% Drug leaching rate (%) = {1 - (Total dry mass of modified wood material after leaching - Total dry mass of untreated wood material) / (Total dry mass of modified wood material - Total dry mass of untreated wood material)} × 100 (Weight increase rate / WPG) Weight gain percentage (WPG) of 20-100%, for example, 25-90%, 30-90%, or 40-90%. Weight Increase Rate (WPG) (%) = [(W t -W0) / W0]×100 (In the formula, W t W0 is the total dry weight (g) of the modified wood material, and W0 is the total dry weight (g) of the untreated wood material. (Bulking / B) 1-10%, for example, 1.5-5% or 2-3% bulking (B) (%) Bulking (B) (%) = [(S t -S0) / S0]×100 (In the formula, S t The end grain area (mm²) of the modified wood material after complete drying. 2 ) and S0 is the end grain area (mm²) of the untreated wood material when completely dry. 2 )) (Dimensional stability (anti-swelling ability) / ASE) ASE of 50% or more, for example 50 - 70%, 55 - 70%, or 55 - 65% Anti-swelling ability (ASE) (%) = [(S c - S t ) / S c × 100 (In the formula, S t is the swelling rate (%) of the cross-sectional area of the modified wood material when it absorbs moisture or water under certain conditions starting from the completely dry state, and S c is the swelling rate (%) of the cross-sectional area of the untreated wood material when it absorbs moisture or water under certain conditions starting from the completely dry state under the same conditions as the modified wood material). The anti-swelling ability ASE is an index representing dimensional stability. When ASE is 50% or more, it is preferable for the actual use of the modified wood material, and less than 50% is not preferable for actual use. In addition, as used in this specification, "completely dry" and "completely dry state" refer to the state of the wood material when the modified wood material or untreated wood material is placed in a thermostat (manufactured by Yamato Scientific Co., Ltd., model: DN43) set at 105°C and the weight change has disappeared. Also, the completely dry weight is the weight of the material when the weight change has disappeared. (Partial compressive strength) The partial compressive strength of the modified wood material measured according to the following test method is preferably 1.4 times or more, for example 1.5 - 3 times or 1.6 - 2.5 times, of the untreated wood material After conditioning the modified wood material, a partial compressive strength test is carried out using a precision universal testing machine (Autograph) manufactured by Shimadzu Corporation in accordance with JIS Z - 2101. The head speed is set at 1 mm / min, and tests are conducted with the grain surface as the compression surface and the cross-grain surface as the compression surface. The value of the partial compressive strength obtained from such a test in accordance with JIS Z - 2101 is compared before and after the modification treatment. Specifically, the ratio of the partial compressive strength of the modified wood material to the untreated wood material is calculated (value of partial compressive strength (times) = partial compressive strength of modified wood material / partial compressive strength of untreated wood material). As can be seen from this testing method, this partial compressive strength serves as an indicator of the hardness of the wood material. A value (ratio) of this partial compressive strength of 1.4 times or more is preferable for the practical use (various actual applications) of the modified wood material. (Durability / decay resistance / decay resistance) The average mass loss rate obtained in accordance with JIS K 1571 "Wood preservatives - Performance standards and test methods thereof", 5.2 Anti-corrosion performance, 5.2.1 Indoor testing, 5.2.1.1 For injection treatment is 3% or less. More specifically, after inoculating modified woody material with fungi (test fungi: *Cortinarius violaceus* and *Trametes versicolor*), the modified woody material is placed in an environment of 26±2°C and relative humidity of 70% or higher for 12 weeks. The average mass loss rate of the modified woody material is then calculated from the weight change before and after this treatment. An average mass reduction rate of 3% or less is preferable for the practical use (various actual applications) of modified wood materials. [Examples]

[0046] The method for producing the modified wood material of the present invention will be described in more detail through the following examples, but the present invention is not limited to these examples.

[0047] (Examples 1-6 and Comparative Examples 1-3) As shown in the table below, various wood specimens were immersed in an aqueous solution containing a chemical agent (hereinafter referred to as "chemical solution"), and the chemical solution was thoroughly permeated into the wood specimens by pressurized and depressurized impregnation. Next, the wood specimens were removed from the chemical solution and heat-treated using a forced-air dryer. More specifically, the wood specimens were immersed in the chemical solution, subjected to a reduced pressure of approximately 50 hPa at room temperature for 2 hours, and then pressurized at 1.0 MPa for 1 hour. After releasing the pressure, the wood specimens were removed from the chemical solution. Next, they were dried using a forced-air dryer at 60°C for 48 hours, followed by drying at 105°C for 48 hours. The dried wood specimens were heated at a predetermined temperature for 4 hours to allow the chemical agent to react.

[0048] [Table 1]

[0049] For each sample, the drug yield, drug leaching rate, weight gain rate, bulking, and ASE were measured. Bulking and ASE were measured before and after three cycles of water absorption and drying.

[0050] [Table 2]

[0051] The results above confirm that wood specimens treated with both citric acid and glycerin showed a high chemical yield, low chemical leaching rate, and high weight increase rate.

[0052] (Examples 7-9) The wood specimens were treated in the same manner as in Examples 4-6, except that the heating time at a specified temperature for the dried wood specimens was changed from 4 hours to 24 hours. For each sample, the drug yield, drug leaching rate, weight increase rate, bulking, and ASE were measured.

[0053] [Table 3]

[0054] The results above confirm that the wood specimens treated for 24 hours showed high chemical yield, low chemical leaching rate, and high weight increase. Furthermore, high ASE (Antimicrobial Stem Cellular Emission) was also confirmed. Considering these results comprehensively, it was determined that treatment at 160°C, which showed excellent results in all indicators, is optimal.

[0055] (Examples 10-14 and Comparative Examples 4-7) As shown in the table below, cedar wood was immersed in a chemical solution, and the chemical solution was thoroughly permeated into the wood specimens by pressurized and depressurized impregnation. Next, the wood specimens were removed from the chemical solution and heat-treated using a forced-air dryer. More specifically, the wood specimens were immersed in the chemical solution, subjected to a reduced pressure of approximately 50 hPa at room temperature for 2 hours, and then pressurized at 1.0 MPa for 1 hour. After releasing the pressure, the wood specimens were removed from the chemical solution. Next, they were dried using a forced-air dryer at 60°C for 48 hours, followed by 105°C for 48 hours. The dried wood specimens were heated at a predetermined temperature for 24 hours to allow the chemicals to react.

[0056] [Table 4]

[0057] For each sample, the drug yield, shrinkage rate, leaching rate after three repeated water absorption and drying cycles, and ASE were measured. The evaluation criteria are as follows.

[0058] [Table 5]

[0059] [Table 6]

[0060] The results above confirmed that citric acid, glutaric acid, and malic acid were superior as acids. In particular, citric acid performed well in all evaluations.

[0061] (Test examples 1-9) As shown in the table below, 33.3 mg (so that the solid content is approximately 10 mg) of each chemical solution, adjusted to a concentration of 30% by mass, was taken and poured into an aluminum pan for thermogravimetric analysis. Using a Seiko Instruments TG / DTA6200 thermogravimetric analyzer, the aforementioned aluminum pan was placed in the sample chamber, and the temperature of the sample chamber was raised at 10°C / min. Dry air was continuously supplied to the sample chamber at 300 ml / min. The temperature was maintained at 100°C for 30 minutes to evaporate the water from the chemical solution, and the mass at this point was used as the standard (100%) for determining the remaining percentage. Subsequently, the temperature was raised to 160°C at 10°C / min and maintained at 160°C for 6 hours to promote the reaction, evaporation, and decomposition of the chemicals (citric acid and polyol).

[0062] [Table 7] (GLYC = Glycerin, EG = Ethylene Glycol, DEG = Diethylene Glycol, TEG = Triethylene Glycol, PG = Propylene Glycol, DPG = Dipropylene Glycol, PEG200 = Polyethylene Glycol 200, PEG400 = Polyethylene Glycol 400, PPG400: Polypropylene Glycol 400)

[0063] For each sample, the drug retention rate was measured after 120 minutes and 360 minutes.

[0064] [Table 8]

[0065] From the results above, it was confirmed that glycerin is superior among polyols in terms of drug retention rate. Looking at the curve of change in retention rate, it could be estimated that the reaction between citric acid and polyol was completed at 120 minutes of heating at 160°C. Assuming the reaction endpoint was 120 minutes, the retention rate at that time was highest for PEG400 and PEG200, followed by TEG, PPG400, and glycerin. Furthermore, comparing the theoretical retention rate, which can be calculated assuming that all carboxyl groups of citric acid and hydroxyl groups of polyol undergo condensation reactions, with the actual retention rate at 120 minutes, PEG400 and glycerin, followed by PEG200, came closest to the theoretical value. From these results, PEG400, glycerin, and PEG200 can be listed as candidates. Furthermore, by continuing heating at 160°C for 240 minutes (360 minutes in total), the decrease in retention rate observed between 120 and 360 minutes can be assumed to be the speed at which the substances formed after the reaction undergo thermal decomposition. The rate of decrease per unit time during this period was 0.75% for glycerin, compared to 1.60% for PEG200 and 2.55% for PEG400, suggesting that the reaction product of glycerin and citric acid is stable against heat. These results demonstrate the superiority of glycerin as a polyol.

[0066] (Test examples 10-20) As shown in the table below, the number of moles of glycerin per mole of citric acid was varied to adjust the concentration to 30% by mass. 33.3 mg of each solution (with a solid content of approximately 10 mg) was taken and poured into an aluminum pan for thermogravimetric analysis. Using a thermogravimetric analyzer from Seiko Instruments Inc., the aforementioned aluminum pan was placed in the sample chamber, and the temperature of the sample chamber was increased at 10°C / min. Dry air was continuously supplied to the sample chamber at 300 ml / min. The temperature was maintained at 100°C for 30 minutes to evaporate the water from the chemical solution, and the mass at this point was used as the baseline (100%) for determining the remaining percentage. Subsequently, the temperature was increased to 160°C at 10°C / min and maintained at 160°C for 6 hours to promote the reaction, evaporation, and decomposition of the chemicals (citric acid and glycerin).

[0067] [Table 9]

[0068] Performing an analysis similar to the results for citric acid and polyol mentioned above, it was confirmed from the above results that the number of moles of glycerin per mole of citric acid is preferably 0.7 to 1.3, more preferably 0.8 to 1.2, even more preferably 0.9 to 1.1, and particularly preferably 1.1.

[0069] (Examples 15-28 and Comparative Examples 8-9) As shown in the table below, cedar wood specimens were immersed in chemical solutions prepared by varying the molar ratio of glycerin to citric acid, and the chemical solutions were thoroughly penetrated into the wood specimens by pressurized and depressurized impregnation. Next, the wood specimens were removed from the chemical solutions and heat-treated using a forced-air dryer. More specifically, the wood specimens were immersed in the chemical solutions, subjected to a reduced pressure of approximately 50 hPa at room temperature for 2 hours, and a pressurized pressure of 1.0 MPa for 1 hour, after which the pressure was released and the specimens were removed from the chemical solutions. Next, they were dried using a forced-air dryer at 60°C for 48 hours, followed by 105°C for 48 hours. The dried wood specimens were heated at 160°C for 24 hours to allow the chemicals to react.

[0070] The results obtained were evaluated using the criteria shown in Table 4, and the results are shown in the table below. When cedar wood was actually treated, the results were excellent when the molar ratio of citric acid to glycerin was 1:0.5 to 1:1.4.

[0071] [Table 10]

Claims

1. A method for manufacturing modified wood material, 1) A step of impregnating an untreated wood material with at least one acid selected from citric acid, malic acid, and glutaric acid, and glycerin to obtain a chemically impregnated wood material, 2) A step of heating the chemical-impregnated wood material obtained in step 1. A manufacturing method that includes this.

2. The manufacturing method according to claim 1, wherein the molar ratio of glycerin to the total number of carboxyl groups of the acid is 0.1 to 0.

5.

3. The manufacturing method according to claim 1, wherein the acid is citric acid, and the molar ratio of glycerin to citric acid is 0.5 to 1.

4.

4. The manufacturing method according to claim 1, wherein step 1 is a step of impregnating an untreated wood material with an aqueous solution containing glycerin and the acid.

5. The manufacturing method according to claim 4, wherein the total concentration of the acid and glycerin in the aqueous solution is 15% by mass or more.

6. The manufacturing method according to claim 4, wherein the total concentration of the acid and glycerin in the aqueous solution is 40% by mass or less.

7. The manufacturing method according to claim 1, wherein the acid is citric acid.

8. The manufacturing method according to claim 1, wherein the heating temperature in step 2 is 130 to 180°C.

9. The manufacturing method according to claim 1, wherein the wood material is coniferous wood.

10. The manufacturing method according to claim 1, wherein the wood material is cedar or cypress.

11. The manufacturing method according to claim 1, further comprising impregnating with a polyol in step 1.

12. The manufacturing method according to claim 11, wherein the polyol is PEG200 or PEG400.

13. A modified wood material produced by the manufacturing method described in claim 1.

14. A modified woody material comprising a reaction product with at least one acid selected from citric acid, malic acid, and glutaric acid, and glycerin.

15. The modified wood material according to claim 13 or 14, used for flooring, decking, exterior wall materials, louvers, furniture, wooden fences, guardrails, exterior materials and / or musical instruments.

Images