Composite material for manufacturing wood-based molded bodies and method for manufacturing the same, and wood-based molded bodies and method for manufacturing the same

Abstract

The present invention provides a composite material for manufacturing wood-based molded articles and a method for manufacturing the same, which allows for the easy production of wood-based molded articles with excellent shape retention and water resistance without the need for the use of resin. [Solution] The composite material for manufacturing wood-based molded articles of the present invention is a composite material used in the manufacture of wood-based molded articles by heat pressing, and is characterized in that at least one wood-based material selected from wood powder, wood chips, and wood boards is impregnated with an aliphatic saturated dicarboxylic acid. The content of the aliphatic saturated dicarboxylic acid is preferably 1 to 80% by mass relative to the composite material for manufacturing wood-based molded articles.

Description

[Technical Field]

[0001] The present invention relates to a composite material for manufacturing wood-based molded articles and a method for manufacturing the same, which are suitable for manufacturing wood-based molded articles with excellent water resistance. [Background technology]

[0002] A technique is known for producing wood-like molded bodies by processing sustainably usable wood—whole timber, waste wood, or recycled wood—into powder, fibers, chips, etc., then placing these materials together with resin or its precursors in a mold cavity and performing compression molding under heated conditions. Studies have been conducted to explore its application to interior materials for vehicles, furniture and other fixtures, flooring, wall materials, and other building materials.

[0003] For example, Patent Document 1 describes a process in which 55 to 75 parts by weight of woody waste pulverized material is placed in a high-speed stirring mixer, 10 to 20 parts by weight of an organic solvent is added to the waste pulverized material, and while stirring and mixing, 25 to 45 parts by weight (in terms of solid content) of a thermosetting resin solution is added and mixed, then granulated, and the granulated mixture is dried at a temperature of 80 to 110°C to obtain a powdered or granular material for woody resin molded articles, which is then compressed and molded to obtain a woody resin molded article.

[0004] Furthermore, Patent Document 2 describes a method in which a blocked isocyanate compound and polyethylene glycol impregnated into a wood material are reacted to form a thermoplastic polyurethane-containing wood material, and then this polyurethane-containing wood material is subjected to molding to obtain a wood-based molded article.

[0005] Here, wood itself has the property of being prone to deformation such as warping, cracking, twisting, and expansion / contraction due to drying and wetting. Therefore, methods to solve these problems are known, such as polyethylene glycol treatment, phenol resin impregnation treatment, acetylation treatment, and esterification treatment. And Patent Document 3 describes aliphatic saturated dicarboxylic acid HOOC(CH2) nA method for improving the dimensional stability of wood is disclosed, characterized by dissolving a COOH group with n of 4 or more, or a derivative thereof, in an organic solvent, water, or a mixture thereof, or by applying a turbidified treatment solution to the wood, or by immersing the wood in the treatment solution to allow the treatment solution to penetrate the wood, and then removing and drying the wood, as well as the modified wood obtained thereby. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 11-300711 [Patent Document 2] WO2023 / 106294 A1 [Patent Document 3] Japanese Patent Application Publication No. 8-336812 [Overview of the project] [Problems that the invention aims to solve]

[0007] In recent years, with the aim of realizing a sustainable and carbon-neutral society, there has been a surge in the effective use of natural materials instead of resins derived from petroleum resources. There are high expectations for the development of new, low-environmental-impact, innovative composite materials that will realize a resource-recycling society. Furthermore, in wood-based molded products used in a wide range of fields, water resistance is required because deformation when wet makes sustainable use impossible.

[0008] The object of the present invention is to provide a composite material for manufacturing wood-based molded articles and a method for manufacturing the same, which allows for the easy production of wood-based molded articles with excellent shape retention and water resistance without the need for the use of resin. [Means for solving the problem]

[0009] The inventors have discovered that impregnating a wood material with an aliphatic saturated dicarboxylic acid yields a composite material suitable for manufacturing wood-based molded articles that exhibits good moldability by heat pressing, excellent shape retention, and water resistance, even without using a resin that can improve shape retention.

[0010] The present invention is shown below. (1) A composite material used in the manufacture of wood-based molded bodies by heating and pressing, A composite material for manufacturing wood-based molded articles, characterized in that at least one wood-based material selected from wood powder, wood chips, and wood boards is impregnated with an aliphatic saturated dicarboxylic acid. (2) The composite material for manufacturing a wood-based molded product according to (1), wherein the content of the aliphatic saturated dicarboxylic acid is 1 to 80% by mass relative to the composite material for manufacturing a wood-based molded product. (3) The above aliphatic saturated dicarboxylic acid is represented by the following general formula, and is a composite material for manufacturing wood-based molded articles as described in (1) above. HOOC-(R 1 ) n -COOH (In the formula, R 1 (where n is an aliphatic saturated hydrocarbon group with 8 or fewer carbon atoms, and n is 0 or 1.) (4) A method for manufacturing a composite material for wood-based molded products as described in (1) above, A method for manufacturing a composite material for wood-based molded articles, characterized by comprising a contact step of contacting the above-mentioned wood-based material with the above-mentioned aliphatic saturated dicarboxylic acid. (5) A method for manufacturing a wood-based molded body, characterized by comprising a shaping step of applying pressure to a material containing the composite material for manufacturing wood-based molded bodies described in (1) above under heating conditions. (6) A wood-based molded body characterized by being obtained by the method described in (5) above. [Effects of the Invention]

[0011] According to the composite material for manufacturing a wood molded body of the present invention, it is suitable for manufacturing a wood molded body having excellent shape retention by heat pressing without using the resin that has been conventionally impregnated for shape retention of the wood molded body. Further, a wood molded body excellent in water resistance can be manufactured, and the obtained wood molded body can be suitably used, for example, as building materials, architectural members, furniture, furnishings, vehicle members, home appliance parts, daily necessities, toys, etc.

Brief Description of the Drawings

[0012] [Figure 1] It is a DMA curve of the composite material for manufacturing a wood molded body obtained in Examples 2-1 to 2-6. [Figure 2] It is a TG curve of the composite material for manufacturing a wood molded body obtained in Examples 2-1, 2-2 and 2-6. [Figure 3] It is a perspective image of the joined body (pressure holding time: 5 minutes) obtained in Example 3-1. [Figure 4] It is a graph showing the liquid absorption rate of the joined body obtained in Example 3-1. [Figure 5] It is a graph showing the elution rate of the joined body obtained in Example 3-1. [Figure 6] It is a perspective image showing the wood molded body (cup) obtained in Example 4-1. [Figure 7] It is a perspective image showing the wood molded body (cup) obtained in Example 4-2. [Figure 8] It is a plan view showing the plate-shaped molded body obtained in Example 5-1.

Embodiments for Carrying Out the Invention

[0013] The composite material for manufacturing a wood molded body of the present invention is characterized in that at least one kind of woody material selected from wood powder, wood chips and wood boards is impregnated with an aliphatic saturated dicarboxylic acid. The composite material for manufacturing a wood molded body of the present invention is a raw material used for manufacturing a wood molded body by heat pressing, and may further contain other materials (described later) depending on the use of the wood molded body and the like.

[0014] The wood material according to the present invention is derived from plant bodies having cell walls, such as coniferous trees like cedar, cypress, and pine; and broad-leaved trees like poplar, beech, oak, and birch. It may also be derived from the plant body itself (sawn boards, veneers, wood chips, powders, fibers, etc.), its waste material, or chemically treated products thereof (deligninized materials, dehemicellulose materials, etc.). In the present invention, the wood material is at least one selected from wood powder, wood chips, and wood boards, and from the viewpoint of impregnation with aliphatic saturated dicarboxylic acid, the preferred size is as follows.

[0015] Regarding the size of the wood powder, the upper limit of the maximum diameter is preferably 1000 μm, more preferably 500 μm, and the lower limit of the maximum diameter is preferably 25 μm, more preferably 100 μm. The shape of the wood powder is not particularly limited.

[0016] The wood chips may be either regular-shaped objects (such as polyhedra) or irregular-shaped objects larger than wood powder, and specifically, they may be lumpy, fibrous, or chip-like. If the wood chips are lumpy, the upper limit of the maximum diameter is preferably 10 mm, more preferably 5 mm, and the lower limit of the maximum diameter is preferably 1 mm, more preferably 2 mm. If the wood chips are fibrous, the upper limit of the maximum diameter of the cross-sectional shape obtained by cutting perpendicular to its length is preferably 5 mm, more preferably 1 mm.

[0017] As described above, the wooden board can be a sawn board, a single board, or a veneer, but it may also be a molded board made of wood powder or wood chips. The size of the wooden board is not particularly limited, but the upper limit of its thickness is preferably 50 mm, more preferably 20 mm.

[0018] The aliphatic saturated dicarboxylic acid according to the present invention is not particularly limited as long as it is a compound in which two hydrogen atoms in an aliphatic saturated hydrocarbon are substituted with carboxyl groups, and may be either a solid or a liquid. The aliphatic saturated dicarboxylic acid contained in the composite material for manufacturing wood molded articles of the present invention may be one type or two or more types. The exact state of the aliphatic saturated dicarboxylic acid in the composite material for manufacturing wood-based molded articles of the present invention is not clear. However, the inventors believe that this includes a mode in which the aliphatic saturated dicarboxylic acid is impregnated into the intracellular lumen or cell wall of the wood material, and a mode in which an ester is formed by a reaction between some of the hydroxyl groups of the wood material and the carboxyl groups of the aliphatic saturated dicarboxylic acid. Including these modes, the present invention is described as "a composite material for manufacturing wood-based molded articles comprising a wood material impregnated with aliphatic saturated dicarboxylic acid."

[0019] The above aliphatic saturated dicarboxylic acid is preferably a compound represented by the following general formula (1). HOOC-(R 1 ) n -COOH (1) (In the formula, R 1 (where n is an aliphatic saturated hydrocarbon group with 8 or fewer carbon atoms, and n is 0 or 1.)

[0020] In the above general formula (1), n ​​is preferably 1, and R 1 The number of carbon atoms is preferably 1 to 8, more preferably 2 to 7.

[0021] The content of aliphatic saturated dicarboxylic acid in the composite material for manufacturing wood-based molded articles of the present invention is preferably 1 to 80% by mass, more preferably 20 to 60% by mass, and even more preferably 30 to 50% by mass, in order to efficiently obtain wood-based molded articles with excellent shape retention by heating and pressing.

[0022] The composite material for manufacturing wood-based molded articles of the present invention is obtained by impregnating a wood-based material with an aliphatic saturated dicarboxylic acid, although the impregnated aliphatic saturated dicarboxylic acid may be exposed on at least a portion of the surface of the wood-based material.

[0023] The composite material for manufacturing wood-based molded articles of the present invention may further include other materials, as described above. Examples of other materials include antioxidants, ultraviolet absorbers, heat stabilizers, plasticizers, fillers, flame retardants, antistatic agents, antibacterial agents, water resistant agents, lubricants, and colorants.

[0024] The composite material for manufacturing wood-based molded articles of the present invention can be manufactured by a method comprising a contact step of contacting a wood-based material with an aliphatic saturated dicarboxylic acid. The specific manufacturing method is as follows.

[0025] The wood material used in the contact step of the composite material manufacturing method for wood-based molded articles of the present invention is derived from a plant body having a cell wall, as described above, and can be at least one selected from wood powder, wood chips, and wood boards derived from the plant body itself, and may also be subjected to conventionally known pretreatment methods, such as a treatment method for acetylating hydroxyl groups in the cell walls of wood tissue.

[0026] In the present invention's method for manufacturing composite materials for wood-based molded articles, the specific operation of the contact step can be selected according to the properties of the aliphatic saturated dicarboxylic acid used. When using a liquid aliphatic saturated dicarboxylic acid, it can be used as is, or a solution obtained by dissolving the aliphatic saturated dicarboxylic acid in a solvent can be used. When using a solid aliphatic saturated dicarboxylic acid, a solution obtained by dissolving the aliphatic saturated dicarboxylic acid in a solvent can be used, or a melt obtained by heating the aliphatic saturated dicarboxylic acid can be used. The solvent can be at least one selected from alcohols, ketones, etc., and the concentration of the aliphatic saturated dicarboxylic acid in the solution can be, for example, 5 to 50% by mass. Another method using solid aliphatic saturated dicarboxylic acids involves heating a mixture of solid aliphatic saturated dicarboxylic acid and a woody material to a temperature above the melting point of the solid aliphatic saturated dicarboxylic acid.

[0027] In the contacting step, when using a solution obtained by dissolving an aliphatic saturated dicarboxylic acid in a solvent, a melt of solid aliphatic saturated dicarboxylic acid, or liquid aliphatic saturated dicarboxylic acid, it is preferable to apply methods such as immersing a wood material in these liquids, spraying these liquids onto the wood material, etc. The contact time between the above liquid and the wood material is appropriately selected according to the shape, size, etc. of the wood material. When immersing the wood material in the above liquid, it can be carried out while adjusting to reduced pressure conditions or pressurized conditions using a sealed container or the like.

[0028] In the contacting step, it is preferable to include a solvent distillation step of distilling off the solvent from the solution-impregnated material after bringing a solution obtained by dissolving an aliphatic saturated dicarboxylic acid in a solvent into contact with the wood material. The method of distilling off the solvent is not particularly limited, and it can be at least one selected from methods such as heating the solution-impregnated material, drying the solution-impregnated material, solvent replacement method, etc. Also, if necessary, distillation can be carried out under reduced pressure conditions.

[0029] Although a composite material for manufacturing a wood molded body in which an aliphatic saturated dicarboxylic acid is impregnated into a wood material can be manufactured by the contacting step, in order to use it as a manufacturing raw material for more reliably obtaining a wood molded body excellent in shape retention and water resistance, it is preferable to further include a heat treatment step of subjecting the obtained aliphatic saturated dicarboxylic acid-impregnated material to heat treatment after the contacting step.

[0030] The heat treatment conditions in the heat treatment step are appropriately set according to the properties and physical properties of the aliphatic saturated dicarboxylic acid. When the aliphatic saturated dicarboxylic acid is a compound in which n is 1 in the above general formula (1) and R 1 is an aliphatic saturated hydrocarbon group having 3 to 8 carbon atoms, the heat treatment temperature is preferably 100 °C or higher, more preferably 130 °C or higher, still more preferably 140 °C or higher, and the upper limit is usually 180 °C. The heat treatment time is appropriately set according to the shape, size, etc. of the aliphatic saturated dicarboxylic acid-impregnated material and is usually 1 hour or more.

[0031] In the above heat treatment process, the aliphatic saturated dicarboxylic acid impregnated material may be subjected to heat treatment while being compressed.

[0032] The present invention relates to a method for manufacturing a wood-based molded body, characterized by comprising a shaping step in which a material including a composite material for manufacturing a wood-based molded body is subjected to pressure under heating conditions. After the shaping step, the present invention relates to a method for manufacturing a wood-based molded body, which may optionally include secondary processing steps such as surface polishing and deburring, and painting steps.

[0033] The material for manufacturing wood-based molded articles of the present invention may further include other materials in addition to the composite material for manufacturing wood-based molded articles. Examples of other materials include wood material, fillers, flame retardants, antistatic agents, antibacterial agents, water resistant agents, lubricants, colorants, etc. The other materials may be included in the material for manufacturing the molded article in an amount of 0 to 50% by mass (preferably 0 to 30% by mass, more preferably 0 to 10% by mass).

[0034] The method for subjecting materials containing composite materials for wood-based molded body manufacturing to the shaping process is not particularly limited. Typically, the composite materials for wood-based molded body manufacturing are placed in a mold and heated and pressed. The form (powder, chips, boards, etc.) and amount of the composite materials used as raw materials for wood-based molded body manufacturing are selected according to the shape of the wood-based molded body. The heating temperature during shaping is set appropriately depending on the type of aliphatic saturated dicarboxylic acid contained, but is preferably 30°C to 180°C, more preferably 80°C to 160°C. The pressure and time during shaping are not particularly limited.

[0035] In this invention, by using a mold and performing a heat press at the above-mentioned preferred temperature, a wood-based molded body with high density and excellent shape retention can be manufactured. Furthermore, since the components contained in the obtained wood-based molded body do not denature, this wood-based molded body can be used as is, or crushed, and then again as a raw material for manufacturing wood-based molded bodies of a desired shape.

[0036] The wood-based molded body manufactured in this manner has excellent water resistance, so even if water adheres to the surface of the molded body, deformation and deterioration are suppressed, and it can be made durable. Therefore, it can be suitably used as building materials, construction components, furniture and furnishings, vehicle components, home appliance parts, daily necessities, toys, etc. Furthermore, in these applications, a composite material consisting of the wood-based molded body and other articles can also be used. In this case, the other article may include one selected from wood or processed wood, resin, metal, alloy, ceramic, glass, carbon fiber, etc. [Examples]

[0037] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0038] 1. Wood-based materials A plate-like material consisting of (X) and (Y) below (untreated plate-like material that has not undergone any pretreatment) was used. (X) Cedar end grain specimen (Y) Cypress veneer sample

[0039] 2. Impregnation materials applicable to wood materials A 25% by mass ethanol solution containing azelaic acid (reagent / chemical grade) manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. (using Fujifilm Wako Pure Chemical Industries, Ltd.'s ethanol (grade 1)) and a 25% by mass ethanol solution containing lauric acid (reagent / chemical grade) manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. (using Fujifilm Wako Pure Chemical Industries, Ltd.'s ethanol (grade 1)) were used.

[0040] 3. Manufacturing and evaluation of composite materials for the production of wood-based molded products (1) A composite material for manufacturing wood-based molded bodies was produced using the above-mentioned cedar board material (X) and a 25% by mass ethanol solution of azelaic acid or a 25% by mass ethanol solution of lauric acid.

[0041] Examples 1-1 to 1-3 A cedar end grain sample (30 mm (fiber direction: L) × 30 mm (radial direction: R) × 5 mm (tangential direction: T)) was immersed in a 25% by mass ethanol solution of azelaic acid (approximately 20°C) contained in a container. The pressure was then reduced (100 hPa, 0.5 hours), and then returned to atmospheric pressure, after which it was allowed to stand (approximately 20°C, 24 hours). Next, the raw material impregnated was removed from the 25% by mass ethanol solution of azelaic acid in the container and air-dried (approximately 25°C, 48 hours). After that, it was dried under reduced pressure (approximately 35°C, 24 hours), and then heated in air (60°C (Example 1-1), 100°C (Example 1-2), or 140°C (Example 1-3), each for 24 hours) to obtain a composite material for manufacturing wood-based molded bodies containing azelaic acid. Composite materials for the manufacture of wood-based molded products containing azelaic acid exhibit a white color at low heating temperatures and a brownish color at high heating temperatures. The weight increase rates due to this azelaic acid treatment were 78.11% (heating temperature: 60°C), 72.01% (heating temperature: 100°C), and 61.04% (heating temperature: 140°C). In addition, the area increase rates, calculated from dimensions measured with digital calipers, were 4.27% (heating temperature: 60°C), 7.42% (heating temperature: 100°C), and 8.28% (heating temperature: 140°C). These results are shown in Table 1.

[0042] Comparative Examples 1-1 to 1-3 Except for using a 25% by mass ethanol solution of lauric acid instead of a 25% by mass ethanol solution of azelaic acid, the same procedures as in Examples 1-1 to 1-3 were followed to obtain composite materials for manufacturing wood-based molded articles containing lauric acid (see Table 1).

[0043] [Table 1]

[0044] Table 1 shows that using azelaic acid, a dicarboxylic acid, resulted in a higher weight increase rate in the resulting composite material for wood-based molded products compared to using lauric acid, a monocarboxylic acid. The inventors speculate that this is because azelaic acid is more readily impregnated into the intracellular lumen and cell wall.

[0045] 4. Manufacturing and evaluation of composite materials for the production of wood-based molded bodies (2) In the same manner as in Examples 1-1 to 1-3, a composite material for manufacturing wood-based molded bodies was produced using the above-mentioned cedar board material (X) and a 25% by mass ethanol solution of azelaic acid, and its thermal softening properties and thermal decomposition properties were evaluated.

[0046] Examples 2-1 to 2-6 Cedar end grain samples (30 mm (fiber direction: L) × 30 mm (radial direction: R) × 5 mm (tangential direction: T)) were subjected to the same procedure as in Examples 1-1 to 1-3. After air-drying the raw material impregnated with a 25% by mass ethanol solution of azelaic acid, the heating temperatures were set to 60°C (Example 2-1), 100°C (Example 2-2), 110°C (Example 2-3), 120°C (Example 2-4), 130°C (Example 2-5), and 140°C (Example 2-6), respectively, to produce composite materials for manufacturing wood-based molded bodies.

[0047] The resulting composite material for wood-based molded body manufacturing was cut so that the latewood portion was sandwiched between the earlywood portions to obtain test specimens (2 mm (fiber direction: L) × 2 mm (radial direction: R) × 2 mm (tangential direction: T)) for dynamic viscoelasticity measurement to evaluate thermal softening characteristics. Dynamic viscoelasticity measurements were then performed using a Seiko Instruments thermomechanical analyzer "TMA / SS6000" (model name) equipped with a TMA compression probe. The measurement conditions were a measurement frequency of 0.03 Hz, a load of -300 mN, and a heating rate of 3 °C / min.

[0048] Figure 1 shows the DMA curves of the composite materials for wood-based molded body manufacturing obtained in Examples 2-1 to 2-6. In the composite materials for wood-based molded body manufacturing obtained in Examples 2-1 to 2-3, a significant decrease in elastic modulus was observed due to an increase in swelling rate accompanying the melting of azelaic acid and the progression of esterification. In the composite materials for wood-based molded body manufacturing obtained in Examples 2-2 and 2-3, significant thermal softening was observed around 100°C to 150°C. On the other hand, the change in elastic modulus with increasing heating temperature was smaller for the composite materials for wood-based molded body manufacturing obtained in Examples 2-4 to 2-6. Furthermore, in all test specimens, it was observed that there was no decrease in elastic modulus or that it increased above 150°C. That is, it was found that the material was given the property of being resistant to deformation above 150°C, and can be said to be in a thermally stable state.

[0049] Next, the composite materials for manufacturing wood-based molded bodies obtained in Examples 2-1, 2-2, and 2-6 were cut so that the latewood portion was sandwiched between the earlywood portions to obtain test specimens (1 mm (fiber direction: L) × 1 mm (radial direction: R) × 1 mm (tangential direction: T)) for evaluating the thermal decomposition characteristics. The test specimens were then placed on an aluminum pan, and thermogravimetric analysis was performed using a Seiko Instruments thermomechanical analyzer "TG / DTA6100" (model name). The temperature was raised from room temperature to 100°C to dry the specimens, and then raised to 500°C at a rate of 5°C / min. For comparison, thermogravimetric analysis was also performed on a cedar board material (X) before contact with a 25% ethanol solution of azelaic acid, and on azelaic acid itself, under the same conditions as above.

[0050] Figure 2 shows the TG curves of the composite materials for wood-based molded body manufacturing obtained in Examples 2-1, 2-2, and 2-6. The temperature at which the weight of the composite material for wood-based molded body manufacturing obtained in Example 2-6 decreased by 1% was 185°C, and it can be seen that there was almost no decomposition up to 185°C, indicating high thermal stability.

[0051] 5. Manufacturing and evaluation of wood-based molded products (1) Using the above-mentioned cypress board material (Y) and a 25% by mass ethanol solution of azelaic acid, a composite material for manufacturing wood-based molded bodies was produced. The obtained composite material for manufacturing wood-based molded bodies was subjected to a heat press to produce various molded bodies.

[0052] Example 3-1 Except for using a cypress veneer sample (52 mm (fiber direction: L) × 1 mm (radial direction: R) × 50 mm (tangential direction: T)), the same procedure as in Example 1-2 was followed to obtain a composite material for manufacturing wood-based molded bodies (hereinafter referred to as "composite material H1 for manufacturing wood-based molded bodies"). Next, five sheets of this plate-shaped composite material H1 for manufacturing wood-based molded bodies were stacked and placed in a mold heated to 170°C. They were then pressed with a punch pressure of 40 MPa (holding time: 5 minutes, 120 minutes, and 1440 hours), cooled to room temperature, and demolded to obtain three types of bonded bodies. The thickness of all of them was approximately 1.5 mm. Figure 3 is a perspective view of the bonded body obtained with a holding time of 5 minutes.

[0053] Subsequently, to evaluate the water resistance and solvent resistance of each joint, test specimens measuring approximately 23 mm x 23 mm x 1.5 mm were prepared by cutting the material. These specimens were then immersed in water and ethanol at approximately 25°C for 24 hours each. The mass of the test specimens was measured before and after immersion, and the liquid absorption rate and leaching rate were calculated using the following formulas (1) and (2). The calculated values ​​were then graphed and shown in Figures 4 and 5, respectively. Liquid absorption rate (%) = 100 × [(Mass of liquid-absorbing test specimen) - (Mass of test specimen before immersion)] / Mass of test specimen before immersion (1) Elution rate (%) = 100 × [(Mass of test specimen before immersion) - (Mass of test specimen after completely drying)] / Mass of test specimen before immersion (2)

[0054] Figures 4 and 5 show the following: The longer the holding pressure time during heating and pressing, the more the wood is heated, causing the reaction of azelaic acid to proceed further, the lower the liquid absorption rate, and the less the azelaic acid leaches out of the wood into the liquid. Azelaic acid is sparingly soluble in water but soluble in ethanol. In the case of a joint obtained with a holding pressure time of 5 minutes, the liquid absorption rate (water) is a slightly high 16%, but the leaching rate is less than 1%, clearly reflecting the property of azelaic acid being poorly soluble in water. On the other hand, the liquid absorption rate (ethanol) is low at 6%, but the leaching rate is 5%, indicating that some leaching occurs, but this becomes almost 0 as the holding pressure time increases. After immersion in water and ethanol, each test specimen maintained its good structure without discoloration or other changes.

[0055] 6. Manufacturing of wood-based molded products (2) We manufactured a cypress wood sake cup using a compression molding die with a sake cup-shaped cavity.

[0056] Example 4-1 The composite material H1 for manufacturing wood-based molded bodies, prepared in Example 3-1, was cut into strips and placed in the above-mentioned compression molding die. Next, the die temperature was set to 170°C and compression molding was performed with a punch pressure of 400kN. The holding time was set to 5 minutes, after which it was cooled to room temperature and demolded to obtain a sake cup with a wood-like texture (see Figure 6).

[0057] Example 4-2 Except for using a cypress veneer sample (52 mm (fiber direction: L) × 1 mm (radial direction: R) × 50 mm (tangential direction: T)), the same procedure as in Examples 1-3 was followed to obtain a composite material for manufacturing wood-based molded bodies (hereinafter referred to as "composite material H2 for manufacturing wood-based molded bodies"). Next, the same procedure as in Example 4-1 was performed, except that composite material H2 for wood molding was used instead of composite material H1 for wood molding, to obtain a sake cup with a wood-like texture (see Figure 7).

[0058] 7. Manufacturing of wood-based molded products (3) A powder was prepared by impregnating wood flour with azelaic acid, and a wood-based molded body was manufactured using this powder.

[0059] Example 5-1 Three parts by mass of wood powder (particle size ~178 μm) manufactured by Naka Wood Co., Ltd. were added to 10 parts by mass of azelaic acid that had been heated to over 100°C to make it liquid, and these were mixed. Then, the mixture was cooled to room temperature to obtain a free-flowing azelaic acid-impregnated powder similar to the original wood powder. Subsequently, the wood powder and azelaic acid-impregnated powder were mixed in a mass ratio of 7:3, and the mixed powder was filled into a mold. The mold temperature was set to 170°C, and compression molding was performed with a punch pressure of 4 MPa (holding time: 5 minutes). After that, it was cooled to room temperature and demolded to obtain a wood-like plate-shaped molded body (25 mm × 27 mm × approximately 1.6 mm) (see Figure 8). [Industrial applicability]

[0060] By using the composite material for manufacturing wood-based molded articles of the present invention, wood-based molded articles with excellent shape retention and water resistance can be efficiently manufactured. These wood-based molded articles can be suitably used as building materials, architectural components, furniture, furnishings, vehicle components, home appliance parts, daily necessities, toys, and the like. Furthermore, these wood-based molded articles can be suitably used for the above-mentioned applications by being integrated with other articles.

Claims

1. A composite material used in the manufacture of wood-based molded bodies by heating and pressing, A composite material for manufacturing wood-based molded articles, characterized in that at least one wood-based material selected from wood powder, wood chips, and wood boards is impregnated with an aliphatic saturated dicarboxylic acid.

2. The composite material for manufacturing a wood-based molded body according to claim 1, wherein the content of the aliphatic saturated dicarboxylic acid is 1 to 80% by mass relative to the composite material for manufacturing a wood-based molded body.

3. The composite material for manufacturing a wood-based molded body according to claim 1, wherein the aliphatic saturated dicarboxylic acid is represented by the following general formula (1). HOOC-(R) １ ) ｎ -COOH (1) (In the formula, R １ (where n is an aliphatic saturated hydrocarbon group with 8 or fewer carbon atoms, and n is 0 or 1.)

4. A method for producing a composite material for manufacturing a wood-based molded body as described in claim 1, A method for manufacturing a composite material for a wood-based molded body, characterized by comprising a contact step of contacting the wood-based material with the aliphatic saturated dicarboxylic acid.

5. A method for manufacturing a wood-based molded body, characterized by comprising a shaping step of applying pressure to a material containing the composite material for manufacturing wood-based molded bodies described in claim 1, under heating conditions.

6. A wood-based molded body characterized by being obtained by the method described in claim 5.

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