Woody decorative material and method for producing same

Abstract

Provided is a woody decorative material having high strength and retaining wood-like appearance. This woody decorative material comprises a woody material and a hydrophobic polymer injected into the woody material. There is a gap between the hydrophobic polymer and lumens in cells of the woody material, yet the hydrophobic polymer is in contact with a cell-lumen-side surface of a cell wall of the cells having a tubular shape.

Description

Wood decorative material and its manufacturing method

[0001] The present disclosure relates to a wood decorative material and a method for producing the same.

[0002] Modified wood has been known in the past, in which properties such as strength and dimensional stability of wood have been changed by modifying the wood.

[0003] For example, Non-Patent Document 1 discloses modified wood in which styrene or methyl methacrylate is injected into the cell cavities of pine and eucalyptus wood and polymerized to fill the cell cavities. Also, Non-Patent Document 2 discloses modified poplar wood in which the surface of the cell cavities of poplar wood is coated with a polymer.

[0004] Denise Ortigosa Stolf et al., "Wood-Polymer Composite: Physical and Mechanical Properties of Some Wood Species Impregnated with Styrene and Methyl Methacrylate" Materials Research, 2004, Vol. 7, No. 4, p.611-617.Denkang Guo et al., "Improving physical properties of wood-polymercomposites by building stable interface structure between swelled cells walls and hydrophobic polymer" Wood Science and Technology, 2021, 55, p.1401-1417.

[0005] An object of the present disclosure is to provide a wood decorative material that has high strength and retains the design characteristics of wood.

[0006] The wood decorative material according to the present disclosure comprises wood material and a hydrophobic polymer injected into the wood material, wherein the hydrophobic polymer has voids in the lumen of the tubular cells of the wood material and is in contact with the surface of the cell wall facing the lumen of the tubular cells.

[0007] The method for manufacturing wood decorative materials according to the present disclosure includes the steps of injecting a hydrophobic polymer dispersed in an aqueous or alcoholic solvent into wood material, and removing the aqueous or alcoholic solvent from the wood material, thereby attaching the hydrophobic polymer to the surface of the cell wall facing the lumen of the tubular cells of the wood material, while leaving gaps in the lumen of the tubular cells.

[0008] The wood decorative material according to the present disclosure has high strength and can retain the design characteristics of wood.

[0009] 1 shows an SEM image of a cross section of an earlywood cedar cell wall with a hydrophobic polymer in contact with the surface of the cell lumen side of the cell wall in a wood decorative material according to embodiment 1. 2 shows a schematic cross section showing a cross section of the lumen of a tubular cell in a wood decorative material according to embodiment 1. 3 shows a schematic cross section showing a cross section perpendicular to the fiber direction of a tubular cell in a wood decorative material. 4 shows SEM images of earlywood and latewood cedar cell wall cross sections. (A) to (D) are a schematic transparent perspective view of a tubular cell showing an untreated state before polymer injection treatment, a cross section showing the cross section structure perpendicular to the fiber direction of the tubular cell, and a cross section showing the cross section structure parallel to the fiber direction of the tubular cell. (A) to (D) are a schematic transparent perspective view of a tubular cell showing a state in which polymer is provided over almost the entire surface of the cell lumen side of the cell wall, a cross section showing the cross section structure perpendicular to the fiber direction of the tubular cell, and a cross section showing the cross section structure parallel to the fiber direction of the tubular cell. (A) to (D) are a schematic perspective view of a tubular cell showing a state in which a polymer is provided over approximately half of the surface of the cell wall on the intracellular lumen side, a cross-sectional view showing the cross-sectional structure of the tubular cell perpendicular to the fiber direction, and a cross-sectional view showing the cross-sectional structure of the tubular cell parallel to the fiber direction. (A) to (D) are a schematic perspective view of a tubular cell showing a state in which a polymer is in contact with part of the surface of the cell wall on the intracellular lumen side, a cross-sectional view showing the cross-sectional structure of the tubular cell perpendicular to the fiber direction, and a cross-sectional view showing the cross-sectional structure of the tubular cell parallel to the fiber direction. A schematic cross-sectional view showing the process of immersing wood material in an emulsion in a manufacturing method for a wood decorative material according to embodiment 1. A schematic cross-sectional view showing the state in which only water penetrates the cell wall and the concentration of polymer particles increases on the surface of the cell wall. A schematic cross-sectional view showing the process of removing the solvent from the wood decorative material.

[0010] (Findings underlying the present disclosure) A major application requiring high-strength wood decorative materials is, for example, building materials. Flooring materials, in particular, require numerous strength and durability characteristics. For example, dent resistance sufficient to withstand heavy objects such as office furniture, surface hardness sufficient to resist scratches caused by dropped objects, and peel resistance sufficient to prevent peeling due to repeated use of furniture with casters. Among flooring materials, decorative materials, being exposed on the surface of the flooring's components, also require high designability. In addition, particularly for such interior building materials, it is desirable that they do not contain harmful substances. Furthermore, lightweight high-strength wood decorative materials can reduce transportation costs and are easy to handle during installation, leading to the expected expansion of their use. Given this background, there is a need for a highly safe method that uses almost no highly harmful VOCs and that improves strength without compromising design while maintaining the lightweight advantage of wood containing tubular cells.

[0011] In recent years, modified wood, in which wood is chemically modified to alter properties such as strength and dimensional stability, has attracted attention. For example, Non-Patent Document 1 discloses modified wood in which styrene or methyl methacrylate is injected into the cell cavities of pine and eucalyptus wood and polymerized to fill the cell cavities. Wood modified in this manner and materials containing it are called WPC (Wood-Polymer Composites, or Wood-Plastic Composites). However, because WPC fills almost all of the intracellular voids, it has the problem of compromising the lightweight nature of wood. Another issue is that the appearance of WPC is similar to that of resin products, and it loses the mellow luster characteristic of wood. This is due to the similar refractive index between wood cells and resin. Designability is an essential factor when using wood as a decorative material.

[0012] Furthermore, for example, Non-Patent Document 2 discloses modified poplar wood, a type of hardwood, in which the surface of the cell cavity of the cell wall is coated with a polymer. However, highly toxic VOCs are used to obtain the modified poplar wood described in Non-Patent Document 2, which raises safety concerns when using the modified poplar wood for industrial purposes.

[0013] The present inventors discovered that by injecting a hydrophobic polymer dispersed in an aqueous or alcoholic solvent into wood and then removing the aqueous or alcoholic solvent from the wood, it is possible to obtain a wood decorative material in which the hydrophobic polymer contacts the lumen-side surface of the cell walls of the tubular cells while retaining voids in the lumen of the tubular cells of the wood, and thus arrived at the present disclosure. The wood decorative material according to the present disclosure has high strength and retains the design characteristics of wood.

[0014] Each aspect of the present disclosure will be described below.

[0015] The wood decorative material of the first aspect comprises wood material and a hydrophobic polymer injected into the wood material, wherein the hydrophobic polymer has voids in the lumen of the tubular cells of the wood material and is in contact with the surface of the cell wall on the lumen side of the tubular cells.

[0016] The wood decorative material of the second aspect may have a polymer impregnation rate of 14% to 80% by weight, which is the ratio of the weight of the injected hydrophobic polymer to the weight of the hydrophobic polymer when the entire volume of the voids in the cell lumen is filled with the hydrophobic polymer in the first aspect.

[0017] A wood decorative material according to a third aspect may be the wood decorative material according to the second aspect, wherein the polymer impregnation rate is 14% by weight to 55% by weight.

[0018] The method for manufacturing a wood decorative material according to the fourth aspect includes the steps of injecting a hydrophobic polymer dispersed in an aqueous or alcoholic solvent into wood material, and removing the aqueous or alcoholic solvent from the wood material, and attaching the hydrophobic polymer to the surface of the cell wall facing the lumen of the tubular cells of the wood material while leaving voids in the lumen of the tubular cells.

[0019] In the fifth aspect of the method for manufacturing a wood decorative material, in the fourth aspect described above, the step of injecting a hydrophobic polymer into the wood material may include the steps of immersing the wood material in a polymer solution in which the hydrophobic polymer is dispersed in an aqueous solvent or an alcohol solvent, and removing the wood material from the polymer solution.

[0020] Hereinafter, wood decorative materials and manufacturing methods thereof according to embodiments of the present disclosure will be described with reference to the accompanying drawings. The present disclosure is not limited to the following embodiments.

[0021] (Embodiment 1) Figure 1A is an SEM image of a cross section of a cell wall of early wood of a cedar tree, which has a hydrophobic polymer in contact with the surface of the cell lumen of the cell wall in a wood decorative material according to embodiment 1. Figure 1B is a schematic cross section showing a cross section of the lumen of a tubular cell in a wood decorative material according to embodiment 1. Wood decorative material 10 according to embodiment 1 has tubular cells and a hydrophobic polymer 7 in contact with at least a portion of the surface of the cell lumen of the cell wall 2 of the tubular cells. The wood decorative material according to embodiment 1 has high strength and can retain a design that resembles wood.

[0022] The elements that make up this wood decorative material are described below.

[0023] <Regarding Wood Materials> Wood materials such as lumber and bamboo can be used. Examples of the wood materials that can be used include solid wood, laminated wood, rotary-laced veneer, and sliced ​​veneer. Wood species that can be used include both softwood and hardwood, and bamboo can also be used. Examples of hardwoods include ash, blue ash, red oak, asada, racemosum, silver maple, silver maple, Japanese snowbell, Japanese walnut, persimmon, katsura, amber oak, paulownia, camphor tree, chestnut, zelkova, Japanese zelkova, cherry tree, Japanese walnut, hornbeams, linden, white oak, white birch, Machilus thunbergii, boxwood, horse chestnut, poplar, black locust, Japanese elm, Japanese alder, beech, magnolia, makamba, dogwood, oak, beech, Japanese beech, Japanese ash, willow, and willow. Some examples include mulberry, acacia mangium, apitong, African mahogany, yellow birch, yellow poplar, yellow meranti, ipe, silver beech, soft maples, dark red meranti, hard maple, basswood, balsa, beech, hickory, bubinga, black walnut, black cherry, white ash, white oak, white meranti, mahogany, light red meranti, and red oak. Examples of coniferous wood include cedar, cypress, red pine, black pine, yew, ginkgo, Japanese yew, Siberian yew, Japanese knotweed, larch, Japanese cedar, sawara, hemlock, Doga sawara, Sakhalin fir, Japanese juniper, hiba, Himekomatsu, fir, agathis, Scots pine, Caribbean pine, pine, Clinky pine, Southern yellow pine, Ponderosa pine, Radiata pine, lodgepole pine, spruce, Japanese holly, Western red cedar, Western hemlock, Japanese hiba, Douglas fir, Japanese fir, Beni pine, Honsun, Japanese larch, Mexican pine, Mexican cypress, redwood, etc. Examples of bamboo include Madake bamboo, Moso bamboo, Hachiku bamboo, and Medake bamboo. The wood decorative material according to this embodiment is particularly effective for low-strength wood species such as cedar.

[0024] Figure 2A is a schematic cross-sectional view of a tubular cell of wood, taken perpendicular to the fiber direction. Figure 2B is an SEM image showing the earlywood 5 and latewood 6 arranged along the radial direction 11 of a cell wall cross-section of coniferous wood (cedar). As shown in Figure 2B, wood is an aggregate of various tubular cells. Among the grains that make up the annual rings, the earlywood 5 is composed of cells that grow rapidly from spring to early summer. On the other hand, among the grains, the latewood 6 is composed of cells that grow rapidly toward the end of summer. In particular, in coniferous wood, the cells that make up the earlywood 5 and latewood 6 are significantly different. The earlywood 5 has a large cell outer diameter of up to approximately 70 μm, a thin cell wall, and a large void 4 in the cell lumen 3, with the thinnest cell being less than 1 μm thick. Therefore, it is believed that the high porosity and low density are the causes of low strength. On the other hand, latewood 6 is characterized by a low porosity due to its small cell outer diameter of 10 μm or less and thick cell walls, with the thickest cells being nearly 5 μm thick. Compared to hardwoods, softwoods grow straighter and have fewer branches, making it easier to procure homogeneous raw materials and more suitable for industrial use. Furthermore, their high porosity makes them lightweight and easy to handle. Furthermore, softwoods have fewer cell types and a simple tissue structure, meaning that differences in properties between tree species are relatively small.

[0025] <About the Hydrophobic Polymer> The hydrophobic polymer is in contact with the wood. For example, the hydrophobic polymer is in contact with the surface of the cell wall of a tubular cell of the wood, the surface facing the lumen of the cell wall. Alternatively, the hydrophobic polymer 7 may be a membrane formed along the cell wall 2 of the lumen of the tubular cell 1 (FIGS. 3A and 3B). FIG. 3A shows an example of a schematic perspective view of a tubular cell 1 in the case where the polymer is not in contact (i.e., untreated), a cross-sectional view showing a cross-sectional structure perpendicular to the fiber direction of the tubular cell 1, and a cross-sectional view showing a cross-sectional structure parallel to the fiber direction of the tubular cell 1. For each structure similar to FIG. 3A, FIG. 3B shows an example in which the polymer 7 covers almost the entire surface of the cell wall 2, FIG. 3C shows an example in which the polymer 7 covers approximately half of the cell wall 2, and FIG. 3D shows an example in which the polymer 7 contacts only a portion of the cell wall 2. Contact with at least a portion of the surface of the cell lumen side of the cell wall of wood does not necessarily mean that the polymer 7 is in contact with almost the entire surface of the cell wall 2, as shown in Fig. 3B. It may also mean that the polymer 7 is in contact with about half of the cell wall 2, as shown in Fig. 3C, or that the polymer 7 is in contact with only a portion of the cell wall 2, as shown in Fig. 3D.

[0026] Furthermore, the polymer does not need to be in uniform contact with the surface of the cell wall facing the lumen; for example, as shown in Figure 3C, there may be areas where the amount of polymer is locally high or low. The amount of polymer in contact with the surface of the cell wall facing the lumen also does not need to be uniform; for example, in multiple cross sections perpendicular to the fiber direction of a tubular cell at any position, the polymer may be formed to completely fill the voids in one cross section, while no polymer is formed at all in another cross section. Furthermore, in a cross section perpendicular to the fiber direction of a tubular cell, some of the cell walls may have polymer formed to completely fill the voids, some have polymer formed on the surface facing the lumen, and some have no polymer formed at all. In other words, the main structure of the cross sections of the multiple tubular cells that make up the woody material may be a hollow cell wall structure, as shown in Figure 1B, in which the polymer is in contact with the surface facing the lumen of the cell wall.

[0027] The hydrophobic polymer is a polymer capable of forming a film and is made of a thermoplastic resin that can promote fusion of resin particles and film formation by heating. Examples of thermoplastic resins include vinyl acetate resin, acrylic resin, styrene-based resin, styrene-acrylic copolymer resin, polyolefin-based resin, polyvinyl chloride resin, polyurethane resin, ABS resin, polyamide resin, polyacetal resin, polycarbonate resin, polyester resin, polyvinyl alcohol, and polyethylene glycol. The hydrophobic polymer may be a copolymer of multiple components or a mixture of multiple thermoplastic resins. It can be used as a dispersion in an aqueous medium or an alcohol solvent, and from the viewpoint of film-forming properties and film hardness after impregnation, vinyl acetate resin, acrylic resin, and styrene-acrylic copolymer resin are particularly preferred.

[0028] <Regarding the manufacturing method of wood decorative material> The manufacturing method of wood decorative material according to embodiment 1 includes the following steps. Figures 4A to 4C are schematic cross-sectional views of each step of the manufacturing method of wood decorative material according to embodiment 1. (1) A step of injecting a hydrophobic polymer dispersed in an aqueous solvent or alcohol solvent into wood material. (2) A step of removing the aqueous solvent or alcohol solvent from the wood material. Through these steps, a wood decorative material can be obtained in which the hydrophobic polymer is attached to the surface of the cell wall facing the lumen of the cell while retaining voids in the cell lumen of the wood material.

[0029] (1) Step of Injecting Hydrophobic Polymer into Wood Material Various methods can be used to inject the hydrophobic polymer. For example, in addition to the atmospheric pressure immersion method, in which the wood material is immersed in a polymer solution in which the hydrophobic polymer is dispersed in an aqueous solvent or an alcohol solvent under atmospheric pressure, a reduced-pressure atmospheric pressure method, in which the wood material is immersed under reduced pressure and then immersed under atmospheric or pressurized pressure, or a reduced-pressure pressurized method can also be used. Furthermore, the hydrophobic polymer may be injected by a coating impregnation method in which the hydrophobic polymer is applied to the wood material and then the surface of the wood material is pressurized. Furthermore, a combination of these methods may be used for injection.

[0030] 4A and 4B, the process of injecting a hydrophobic polymer into wood material may include the following steps: (1-1) immersing the wood material in a polymer solution prepared by dispersing a hydrophobic polymer in an aqueous or alcoholic solvent (FIGS. 4A and 4B), and (1-2) removing the immersed wood material from the polymer solution. When the wood material is immersed in the polymer solution 12, only the water solvent 16 penetrates the cell walls 2, and the polymer particles 14 dispersed in the wood material 12 increase in local concentration on the surface of the cell lumen side of the cell walls 2, fusing together at the surface of the cell walls to form a fused mass 15.

[0031] <Hydrophobic Polymer> The hydrophobic polymer is a hydrophobic polymer dispersed in an aqueous or alcoholic solvent, preferably a polymer whose main component is, for example, a vinyl acetate resin, an acrylic resin, or a styrene-acrylic copolymer resin. Because polymer particles made of a hydrophobic polymer dispersed in an aqueous or alcoholic solvent are hydrophobic, they do not penetrate into the cell walls of the lumen of the tubular cells of hydrophilic wood. Furthermore, the viscosity can be adjusted by controlling the solids concentration and temperature.

[0032] <Water-based or alcoholic solvent> The solvent is a water-based or alcoholic solvent. Therefore, no highly harmful volatile organic solvent (VOC) is used, the resulting wood decorative material can be prevented from inducing sick house syndrome, and it also has excellent workability.

[0033] (2) Step of Removing the Aqueous Solvent or Alcohol Solvent from the Wood Material After the hydrophobic polymer is injected, the treated wood material is dried to evaporate the aqueous or alcohol solvent, and then heated to a temperature equal to or higher than the curing temperature of the hydrophobic polymer to cure the hydrophobic polymer. Methods for evaporating the aqueous or alcohol solvent include air drying, forced drying with warm or hot air, and vacuum drying under reduced pressure. Alternatively, a combination of methods may be used to remove the aqueous or alcohol solvent.

[0034] <About the Amount of Hydrophobic Polymer Impregnated> The amount of hydrophobic polymer impregnated can be determined as appropriate within a range that increases the strength of the wood material while maintaining the woody texture, such as the appearance and feel unique to wood material. As shown in the following formula, the polymer impregnation rate (wt % or wt %) is the ratio of the weight of the injected hydrophobic polymer to the weight of the hydrophobic polymer when the entire volume of the cell lumen is filled with the hydrophobic polymer. Polymer impregnation rate (wt %) = (weight of injected hydrophobic polymer) / (weight of hydrophobic polymer when the entire volume of the cell lumen is filled with the hydrophobic polymer (weight of hydrophobic polymer when completely filled)). Specifically, the polymer impregnation rate when the voids in the wood material are completely filled with the polymer is defined as 100 wt %. A polymer impregnation rate of 14 wt % or higher provides sufficient compressive strength for use as a decorative material, while a polymer impregnation rate of 80 wt % or lower allows the woody texture to be retained. Preferably, a polymer impregnation rate of 14 to 55 wt % provides wood decorative materials with sufficient compressive strength and a high woody texture.

[0035] To calculate the "polymer impregnation rate," a piece of wood having the same density and voids as the wood to be used is completely filled with the hydrophobic polymer, and the weight change is measured to determine the weight of the hydrophobic polymer when the polymer impregnation rate is 100% by weight. In reality, different pieces of wood are used each time, so the wood used in the "completely filled" case at the bottom is not in exactly the same condition as the wood to be used subsequently, but is used only as if approximately the same wood were used.

[0036] <Determining the range of polymer impregnation rate to achieve lateral compressive strength (5.9 MPa or more) equivalent to that of Japanese cypress, suitable for use as a wood decorative material> Samples with different polymer impregnation rates were prepared by varying the concentration of the polymer solution, in which a hydrophobic polymer was dispersed in an aqueous or alcoholic solvent, and the number of impregnation times, and the samples were evaluated for lateral compressive strength. The relationship between polymer impregnation rate (wt%) and lateral compressive strength is shown in Table 1 below.

[0037]

[0038] As shown in Table 1 above, when the polymer impregnation rate (wt%) is 0 wt%, i.e., when the wood is untreated, the lateral compressive strength is only 3.0 MPa. In contrast, as the polymer impregnation rate (wt%) increases, the lateral compressive strength also increases. It was found that by increasing the polymer impregnation rate (wt%) to 14 wt% or more, the lateral compressive strength can be increased to 5.9 MPa or more, equivalent to that of Japanese cypress.

[0039] <Determining the range of polymer impregnation rate that does not impair the wood texture (wood-likeness)> Samples were prepared by changing the polymer impregnation rate by varying the concentration of the polymer solution, and the appearance was evaluated. The relationship between the polymer impregnation rate (wt%) and the wood texture evaluated based on the appearance and tactile sensation is shown in Table 2 below.

[0040]

[0041] As shown in Table 2 above, when the polymer impregnation rate (wt%) was 0 wt%, the original wood texture remained, whereas when the polymer impregnation rate (wt%) was 100 wt%, the product resembled a resin product and no wood texture remained. As the polymer impregnation rate (wt%) was increased, the wood texture gradually disappeared, but it was found that by setting the polymer impregnation rate (wt%) to 80 wt% or less, it was possible to maintain a state in which the wood texture, as evaluated based on appearance and tactile sensation, remained.

[0042] Example 1: A cedar block (10 mm x 10 mm x 2 mm in the fiber direction) was immersed in an emulsion (Polysol BX-8004, manufactured by Resonac Corporation) primarily composed of vinyl acetate resin and held at a reduced pressure of -0.09 MPa (approximately 0.01 MPa (0.1 atm)) for 10 minutes to remove air bubbles from the wood. The pressure was then increased to 0.85 MPa (8.5 atm) with air gas and held for 30 minutes to allow impregnation. The cedar block was removed, excess liquid was wiped off, and the block was dried at room temperature and pressure for 24 hours. The remaining moisture was then removed, and the block was further heated and dried at 110°C for 60 hours to promote fusion and film formation of the hydrophobic polymer particles.

[0043] A 2mm square sample was cut from the treated wood and subjected to a lateral compression test. Assuming use as plain grain lumber, the test was conducted using a universal testing machine (Shimadzu Corporation) so that a compressive load was applied in the radial direction of the annual rings (N=3). The relationship between the solids concentration (wt%) of the polymer solution, the polymer impregnation rate (wt%), and the lateral compressive strength (MPa) is shown in Table 3 below.

[0044]

[0045] As shown in Table 3, the polymer impregnation rate (wt%) can be increased by increasing the concentration of the polymer solution. However, in order to increase the polymer impregnation rate (wt%) beyond 50 wt%, it was necessary to perform the impregnation treatment multiple times.

[0046] Unlike the WPC manufacturing method, in which reactive monomers are impregnated into wood and cured within the wood, the wood decorative material according to the present disclosure does not leave a large amount of uncured monomers in the wood decorative material. The emulsion used here (mainly composed of vinyl acetate resin) contains less than 1% uncured monomers. This significantly reduces the possibility of VOCs being released from the resulting wood decorative material, which can cause sick building syndrome and other symptoms.

[0047] The wood decorative material according to the present disclosure has high strength and retains the design characteristics of wood, and therefore can be used as architectural interior materials such as flooring and as structural materials.

[0048] REFERENCE SIGNS LIST 1 tubular cell 2 cell wall 3 cell lumen 4 cavity 5 earlywood 6 latewood 7 polymer 10, 10a wood decorative material 11 radial direction 12 emulsion 14 polymer particle 15 fused material 16 solvent (water)

Claims

1. A wood decorative material comprising: a wood material; and a hydrophobic polymer injected into the wood material, wherein the hydrophobic polymer has voids in the lumen of tubular cells of the wood material and is in contact with the surface of the cell lumen side of the cell wall of the tubular cells.

2. The wood decorative material according to claim 1, wherein the polymer impregnation rate, expressed as the ratio of the weight of the hydrophobic polymer injected to the weight of the hydrophobic polymer when the entire volume of the voids in the cell lumen is filled with the hydrophobic polymer, is 14% by weight to 80% by weight.

3. The wood decorative material according to claim 2, wherein the polymer impregnation rate is 14% by weight to 55% by weight.

4. A method for producing a wood decorative material, comprising: a step of injecting a hydrophobic polymer dispersed in an aqueous or alcoholic solvent into wood material; and a step of removing the aqueous or alcoholic solvent from the wood material, wherein the hydrophobic polymer is attached to the surface of the cell lumen side of the cell wall of the tubular cells of the wood material while leaving gaps in the lumen of the tubular cells.

5. A method for manufacturing a wood decorative material as described in claim 4, wherein the step of injecting the hydrophobic polymer into the wood material includes the steps of: immersing the wood material in a polymer solution in which the hydrophobic polymer is dispersed in the aqueous solvent or alcohol solvent; and removing the wood material from the polymer solution.

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