Wood substrates and decorative materials

Abstract

To provide a woody base material which inhibits the emission of harmful substances such as formaldehyde becoming a possible cause of sick house syndrome and comprises practical mechanical strength and water resistance, and to provide a decorative material comprising the woody base material and a production method for the woody base material.SOLUTION: A woody base material 20 according to the present embodiment includes a woody material 11 having at least one of a powder-like shape and a chip-like shape, a thermoplastic resin composition 12 and a water-soluble resin. The water-soluble resin is polyvinyl alcohol having a saponification degree of 90 mol% or more, and the content of this resin is in a range of 0.3 pts.mass to 5 pts.mass based on total 100 pts.mass of the woody material 11 and the thermoplastic resin composition 12, and a mass ratio of the woody material 11 to the thermoplastic resin composition 12 (woody material / thermoplastic resin composition) is 95 / 5 to 65 / 35.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a wood substrate, and makeup Material Regarding. [Background technology]

[0002] Wood substrates are made by heating and pressurizing a mixture of wood materials such as wood flour, wood chips, and wood fiber with an adhesive. These wood substrates are called particle boards, medium-density fiberboards, etc., depending on the type of wood material, and are used in a wide range of applications, including as underlayment for floors and walls, as well as for building materials and furniture.

[0003] Urea resin adhesives, melamine resin adhesives, or phenolic resin adhesives are typically used with formaldehyde-containing curing agents for wood substrates. Formaldehyde is a harmful substance that can cause sick building syndrome, so its emission from wood substrates is a problem. Various measures have been considered to reduce the amount of formaldehyde emitted, but it is not possible to completely suppress it.

[0004] In response to this, a method has been proposed in the past for producing fiberboards by using an adhesive whose main components are powdered sugars and powdered polycarboxylic acids as formaldehyde-free adhesives, mixing this with plant fibers, and molding it under heat and pressure (see paragraph

[0017] of Patent Document 1).Also, a method has been proposed for producing laminates containing wood substrates using an adhesive consisting of polyvinyl alcohol and water as a formaldehyde-free adhesive (see paragraph

[0017] and Figure 1 of Patent Document 2). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-55620 [Patent Document 2] Patent No. 5553279 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the wood substrates using the above-mentioned conventional adhesives are not practically sufficient in terms of mechanical properties such as bending strength and water resistance. The present invention has been made in view of the above-mentioned problems, and aims to provide a wood substrate that suppresses the emission of harmful substances such as formaldehyde that cause sick building syndrome and that has practical mechanical strength and water resistance, a decorative material that includes this wood substrate, and a method for manufacturing this wood substrate.

[0007] As a result of intensive research into solving the above-mentioned problems, the inventors have found that the above-mentioned problems can be solved by adding a polyvinyl alcohol solution to a powder mixture of a wood material and a thermoplastic resin composition, which is formed by heating and pressurizing the powder mixture, and have arrived at the present invention. [Means for solving the problem]

[0008] A wood substrate according to one embodiment of the present invention comprises a wood material in at least one of powder and chip form, a thermoplastic resin composition, and a water-soluble resin, wherein the water-soluble resin is polyvinyl alcohol with a saponification degree of 90 mol% or more, the content of which is in the range of 0.3 to 5 parts by mass per 100 parts by mass of the wood material and the thermoplastic resin composition combined, and the mass ratio of the wood material to the thermoplastic resin composition (wood material / thermoplastic resin composition) is 95 / 5 to 65 / 35.

[0009] Furthermore, one embodiment of the present invention provides a decorative material using a wood base material containing a wood material in at least one of powder and chip form, a thermoplastic resin composition, and a water-soluble resin, wherein the water-soluble resin is polyvinyl alcohol with a saponification degree of 90 mol% or more, and the content thereof is within the range of 0.3 to 5 parts by mass per 100 parts by mass of the wood material and the thermoplastic resin composition combined, and a decorative layer having a design effect is laminated on the wood base material.

[0010] A method for producing a wood substrate according to one aspect of the present invention includes a step of mixing the water-soluble resin solution with a mixture of the wood material and the thermoplastic resin composition. [Effects of the Invention]

[0011] According to one aspect of the present invention, it is possible to provide a wood substrate that suppresses the emission of harmful substances such as formaldehyde that cause sick building syndrome and that has practical mechanical strength and water resistance, a decorative material that includes this wood substrate, and a method for manufacturing this wood substrate. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a schematic diagram illustrating the cross-sectional structure of a wood base material according to a first embodiment of the present invention and a manufacturing process for the wood base material. [Figure 2] FIG. 3 is a schematic cross-sectional view showing the structure of a decorative material according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The drawings are schematic, and the relationship between thickness and planar dimensions, the thickness ratio of each layer, etc., differ from the actual ones. Furthermore, the embodiments shown below are merely examples of configurations for embodying the technical idea of ​​the present invention, and the technical idea of ​​the present invention does not specify the materials, shapes, structures, etc. of the components to those described below. The technical idea of ​​the present invention can be modified in various ways within the technical scope defined by the claims.

[0014] (First embodiment) Fig. 1 is a schematic diagram showing the cross-sectional structure of a wood substrate according to a first embodiment of the present invention and a method for manufacturing the wood substrate. In Fig. 1, reference numeral 20 denotes the wood substrate according to the first embodiment of the present invention. The wood substrate 20 is called particle board, medium-density fiberboard, or the like depending on the type of wood material 11 that constitutes the wood substrate 20, and is used in a wide range of applications, such as underlayment for floors and walls, building materials, and furniture.

[0015] As shown in Figure 1, the wood substrate 20 is formed by heating and pressurizing a raw material mixture 10 containing a wood material 11 in at least one of powder and chip form, a powdered thermoplastic resin composition 12, and a water-soluble resin. The wood substrate 20 does not contain harmful substances that cause sick building syndrome, such as formaldehyde. Therefore, the emission of harmful substances that cause sick building syndrome, such as formaldehyde, from within the wood substrate 20 can be suppressed. The structure of the wood substrate 20 according to this embodiment will be described in detail below.

[0016] (Wood material 11) The wood material 11 has at least one of a powder and chip form. Here, the terms "powder" and "chip" do not generally have definitions of size or shape. In this embodiment, the term refers to a material whose size (average particle size) is generally in the range of several tens of microns to several centimeters. The average particle size (D50) of the wood material 11 in this embodiment is preferably in the range of 100 μm to 30 mm, for example.

[0017] Examples of the wood material 11 include wood flour, wood fiber, and wood crushed into chips, and as raw materials, thinned wood, sawdust, waste wood, and the like can also be used. Furthermore, materials other than wood can also be used as the wood material 11, such as bamboo, hemp, coconut fiber, and walnut shells, as long as they contain cellulose components similar to wood.

[0018] A suitable raw material for the wood material 11 is, for example, used mushroom beds, which are generated in large quantities during mushroom cultivation. The mushroom beds are a medium used for mushroom cultivation and are made by mixing wood chips and sawdust with nutrients such as wheat bran and rice bran. It is estimated that around 300,000 tons of mushroom beds are discarded annually in Japan after mushroom cultivation, making them a promising source of biomass, but recycling is currently not progressing well.

[0019] In this embodiment, when a fungal bed is used as the wood material 11, the proportion of the fungal bed in the total volume of the wood material 11 may be in the range of 1% to 100%, preferably in the range of 50% to 100%, and more preferably in the range of 80% to 100%. If the content of the fungal bed is within the above range, the production cost can be reduced compared to when ordinary wood chips are used.

[0020] (Thermoplastic resin composition 12) The raw material mixture 10 contains one or more thermoplastic resin compositions 12. The thermoplastic resin composition 12 contains one or more thermoplastic resins.

[0021] The thermoplastic resin contained in the thermoplastic resin composition 12 can be various, such as polyester, polyamide, polyolefin, ethylene-propylene-diene rubber, ethylene vinyl acetate, and silicone rubber, but polyethylene is preferred in terms of the mechanical strength and water resistance of the wood substrate 20.

[0022] The polyethylene is not particularly limited, and may be appropriately selected from existing materials such as high-density polyethylene (polyethylene with a specific gravity of approximately 0.92 to 0.96), low-density polyethylene (polyethylene with a specific gravity of approximately 0.91 to 0.92), ultra-low-density polyethylene (polyethylene with a specific gravity of less than 0.9), and linear low-density polyethylene (polyethylene with a specific gravity of less than 0.94), taking into consideration the fluidity of the raw material mixture 10. The thermoplastic resin may be a resin containing an acid to improve adhesion of the wood material 11 to the thermoplastic resin. Examples of the acid-containing resin that can be used include maleic anhydride-modified polyethylene, maleic anhydride polypropylene, maleic anhydride-modified polyolefin, ethylene (meth)acrylic acid copolymer, and itaconic anhydride-modified polyethylene.

[0023] The amount of the acid-containing resin added is preferably in the range of 5 to 50 parts by mass, more preferably 10 to 40 parts by mass, per 100 parts by mass of the entire thermoplastic resin composition. If the amount of the acid-containing resin added is less than 5 parts by mass, the adhesion between the wood material 11 and the thermoplastic resin composition 12 will be insufficient, and sufficient strength may not be imparted to the wood substrate 20. If the amount of the acid-containing resin added exceeds 50 parts by mass, the strength of the wood substrate 20 may decrease.

[0024] The raw material mixture 10, more specifically the thermoplastic resin composition 12, may contain an organic peroxide to crosslink the thermoplastic resin during the heat pressing process to form the substrate. Crosslinking may improve the strength and water resistance of the wood substrate 20. The organic peroxide to be added to the raw material mixture 10 may be appropriately selected from existing materials such as peroxyketals, dialkyl peroxides, diacyl peroxides, and peroxyesters, taking into consideration their reactivity and stability.

[0025] The amount of organic peroxide added is preferably in the range of 0.1 to 5 parts by mass, more preferably in the range of 0.5 to 4 parts by mass, per 100 parts by mass of the total thermoplastic resin composition. If the amount of organic peroxide added is less than 0.1 parts by mass, the raw material mixture 10 will not be sufficiently reactive when heated and pressurized, and will not contribute to improving the strength of the wood substrate 20. If the amount of organic peroxide added is more than 5 parts by mass, the amount of decomposition products produced during the reaction will increase, which may cause deformation of the wood substrate 20.

[0026] Among the thermoplastic resin compositions 12, those containing multiple components can be produced by various known methods. The thermoplastic resin composition 12 containing multiple components can be produced, for example, by using a single-screw kneader or a batch kneader to heat and knead a thermoplastic resin and other raw materials, and then pulverizing the mixture by a method such as mechanical crushing or freeze crushing.

[0027] The mass ratio of the wood material 11 to the thermoplastic resin composition 12 (wood material / thermoplastic resin composition) is within a range of 95 / 5 to 65 / 35. Furthermore, the mass ratio of the wood material 11 to the thermoplastic resin composition 12 (wood material / thermoplastic resin composition) is more preferably within a range of 95 / 5 to 75 / 25, and even more preferably within a range of 90 / 10 to 80 / 20. If the content of the wood material 11 is greater than the above-mentioned value (95 / 5), sufficient strength may not be imparted to the wood substrate 20. On the other hand, if the content of the wood material 11 is less than the above-mentioned value (65 / 35), the raw material mixture 10 may not be uniformly mixed, and the strength and water resistance of the wood substrate 20 may be reduced.

[0028] (Water-soluble resin) The water-soluble resin used is polyvinyl alcohol (PVA), which is mixed in the form of an aqueous solution into the raw material mixture 10. Because the aqueous polyvinyl alcohol solution is adhesive, the thermoplastic resin composition 12 adheres to the wood material 11 in the raw material mixture 10 via the polyvinyl alcohol, resulting in a uniformly mixed raw material mixture 10 and improving the water resistance and strength of the wood substrate 20.

[0029] The polyvinyl alcohol must have a degree of saponification of 90 mol% or more, and a degree of saponification of 97 mol% or more is more preferable from the viewpoint of the water resistance of the wood substrate 20. If the degree of saponification of polyvinyl alcohol is less than 90 mol%, the water resistance of the wood substrate will be significantly reduced. The saponification reaction of polyvinyl alcohol and the measurement of the degree of saponification of polyvinyl alcohol can be carried out by known methods.

[0030] The amount of polyvinyl alcohol blended per 100 parts by mass of the combined total of wood material 11 and thermoplastic resin composition 12 is within the range of 0.3 parts by mass or more and 5 parts by mass or less. Furthermore, the amount of polyvinyl alcohol blended per 100 parts by mass of the combined total of wood material 11 and thermoplastic resin composition 12 is more preferably within the range of 1.0 parts by mass or more and 3 parts by mass or less. If the amount of polyvinyl alcohol blended is less than the above value (0.3 parts by mass), the raw material mixture will not be sufficiently uniform, and the strength and water resistance of the wood substrate will be reduced. Furthermore, if the amount of polyvinyl alcohol blended is greater than the above value (5 parts by mass), not only will the strength and water resistance of the wood substrate be reduced, but the raw material mixture will be prone to clumping, causing problems in the manufacturing process.

[0031] The polyvinyl alcohol preferably contains acetoacetyl groups, which crosslink with each other during thermocompression of the wood substrate 20, improving the strength and water resistance of the wood substrate 20. The content of structural units having acetoacetyl groups in the above-mentioned acetoacetyl group-containing polyvinyl alcohol is preferably in the range of 0.1 mol % to 20 mol %, more preferably in the range of 0.5 mol % to 15 mol %.

[0032] The polyvinyl alcohol aqueous solution may contain a crosslinking agent. Crosslinking of the polyvinyl alcohol during thermocompression of the wood substrate 20 is expected to improve the water resistance and strength of the wood substrate 20. Commercially available materials, such as crosslinked amines, hydrazide compounds, and metal salts such as zirconium, can be used as the crosslinking agent contained in the polyvinyl alcohol aqueous solution. The content of the crosslinking agent is preferably in the range of 1 to 10 parts by mass per 100 parts by mass of polyvinyl alcohol.

[0033] The concentration of the aqueous polyvinyl alcohol solution is appropriately set depending on the molecular weight of the polyvinyl alcohol, but is usually about 10 wt % or less.

[0034] (Preparation of raw material mixture 10) In the process for preparing raw material mixture 10, it is preferable to add and mix an aqueous polyvinyl alcohol solution having a saponification degree of 90 mol% or higher to a mixture of wood material 11 and thermoplastic resin composition 12 so that the blending amount is in the range of 0.3 parts by mass to 5 parts by mass per 100 parts by mass of the total of wood material 11 and thermoplastic resin composition 12. For example, raw material mixture 10 can be obtained by adding the aqueous polyvinyl alcohol solution with a sprayer or the like while stirring wood material 11 and thermoplastic resin composition 12.

[0035] (Heating and pressurizing raw material mixture 10) Various known methods can be used to heat and pressurize the raw material mixture 10, but press molding using a mold is preferred. The heating temperature must be equal to or higher than the melting point of the thermoplastic resin contained in the thermoplastic resin composition 12, and is typically 120°C to 250°C. Temperatures above 250°C cause significant thermal degradation of the wood material 11. The pressure applied is typically 10 to 200 kgf / cm. 2 and the value is set appropriately depending on the desired density of the wooden substrate 20. The density and shape of the wooden substrate 20 are determined appropriately depending on the application, but the density is preferably 0.5 to 1.2 g / cc, and more preferably 0.6 to 1.1 g / cc.

[0036] (Second embodiment) The second embodiment will be described with reference to Figure 2. Although the wooden substrate 20 can be used as a decorative material by itself, to provide a decorative element, a decorative substrate (design layer) 31 such as paper or film with a design such as a picture may be laminated onto the wooden substrate 20 to form a decorative element 30, as shown in Figure 2.

[0037] [Example] Below, examples 1 to 5 of the wood base material according to the first embodiment of the present invention and comparative examples 1 to 5 will be explained. Note that the present invention is not limited to the following examples 1 to 5.

[0038] Example 1 In Example 1, 90 parts by mass of low-density polyethylene resin and 10 parts by mass of acid-modified polyolefin resin (UMEX 100TS, manufactured by Sanyo Chemical Industries, Ltd.) were heated and kneaded in a batch kneader, and then mechanically pulverized to obtain a powdery thermoplastic resin composition.

[0039] The water-soluble resin solution was prepared by dissolving polyvinyl alcohol (PVA) (saponification degree 93 mol%), which is a water-soluble resin, in pure water to prepare a polyvinyl alcohol aqueous solution with a concentration of 5 wt %.

[0040] The wood material used was dried mushroom beds that had been washed after harvesting.

[0041] While stirring the above-mentioned wood material and thermoplastic resin composition in a mixer, the above-mentioned water-soluble resin solution was sprayed with an air spray, and stirring was continued to obtain a raw material mixture with the following mixing ratio (mass ratio) (wood material / thermoplastic resin composition / water-soluble resin = 85 / 15 / 2). Hereinafter, the mixing ratio of the constituent materials of the raw material mixture will be expressed as a mass ratio.

[0042] This raw material mixture was placed in an aluminum mold and heated and pressurized in a heat press to obtain a wood substrate with a density of 0.7 g / cc (pressing conditions: 30 kgf / cm 2 , 170℃ for 10 minutes, base material thickness: 10mm). In this embodiment, the wood base material does not contain harmful substances such as formaldehyde that can cause sick house syndrome.

[0043] Example 2 In Example 2, a wood substrate was obtained in the same manner as in Example 1, except that the polyvinyl alcohol in the water-soluble resin solution in Example 1 was replaced with polyvinyl alcohol having a saponification degree of 98 mol %.

[0044] Example 3 In Example 3, the mixing ratio of the raw material mixture (wood material / thermoplastic resin composition / water-soluble resin) was changed from "85 / 15 / 2" in Example 2 to "85 / 15 / 4," and otherwise the wood base material was obtained in the same manner as in Example 2.

[0045] Example 4 In Example 4, the mixing ratio of the raw material mixture (wood material / thermoplastic resin composition / water-soluble resin) was changed from "85 / 15 / 2" in Example 2 to "70 / 30 / 2," and otherwise the wood base material was obtained in the same manner as in Example 2.

[0046] Example 5 In Example 5, the polyvinyl alcohol in the water-soluble resin solution of Example 2 was replaced with an acetoacetyl group-containing polyvinyl alcohol (Gohsenex Z300, saponification degree 98 mol%, manufactured by Mitsubishi Chemical Corporation), and the wood substrate was obtained in the same manner as in Example 2.

[0047] (Comparative Example 1) In Comparative Example 1, the mixing ratio of the raw material mixture (wood material / thermoplastic resin composition / water-soluble resin) was changed from "85 / 15 / 2" in Example 1 to "85 / 15 / 0.2," and otherwise the wood base material was obtained in the same manner as in Example 1.

[0048] (Comparative Example 2) In Comparative Example 2, a wood base material was obtained in the same manner as in Example 1, except that the polyvinyl alcohol in the water-soluble resin solution in Example 1 was replaced with polyvinyl alcohol having a degree of saponification of 87 mol %.

[0049] (Comparative Example 3) In Comparative Example 3, the mixing ratio of the raw material mixture (wood material / thermoplastic resin composition / water-soluble resin) was changed from "85 / 15 / 2" in Example 2 to "85 / 15 / 6," and otherwise the wood base material was obtained in the same manner as in Example 2.

[0050] Comparative Example 4 In Comparative Example 4, the mixing ratio of the raw material mixture (wood material / thermoplastic resin composition / water-soluble resin) was changed from "85 / 15 / 2" in Example 2 to "60 / 40 / 2," and otherwise the wood base material was obtained in the same manner as in Example 2.

[0051] (Comparative Example 5) In Comparative Example 5, a wood base material was obtained in the same manner as in Example 1, except that the polyvinyl alcohol in the water-soluble resin solution in Example 1 was replaced with polyacrylic acid.

[0052] (Evaluation of wood substrates) The physical properties of the wood substrate were evaluated based on the following two points: (1) mechanical strength and (2) water resistance.

[0053] (1) Mechanical strength The mechanical strength was measured by bending strength according to the method of JISA5908. The measured value (unit: N / mm 2 The evaluation criteria for mechanical strength of the test piece were four levels: ◎, ○, △, and ×, with ◎, ○, and △ being considered pass, and × being fail.

[0054] ◎:18 or above (pass) ○: 13 or more and under 18 (pass) △: 8 or more but less than 13 (pass) ×: Less than 8 (fail)

[0055] (2) Water resistance Water resistance was measured by measuring the water absorption thickness swelling rate in accordance with JISA 5908. The evaluation criteria for the measured value (unit: %) were as follows: "○", "△", and "×", with "○" and "△" representing pass and "×" representing fail.

[0056] ○: Less than 8 (pass) △: 8 or more but less than 12 (pass) ×: 12 or more (fail)

[0057] (Evaluation results) The evaluation results of the wood base materials are shown in Table 1. Examples 1 to 5 were "passed" in both physical property evaluation points, while Comparative Examples 1 to 5 all failed in water resistance.

[0058] [Table 1]

[0059] It is presumed that the causes of the problem in Comparative Example 1 are that the content of the water-soluble resin contained in the raw material mixture is too low, that in Comparative Example 2 the saponification degree of the polyvinyl alcohol is too low, that in Comparative Example 3 the amount of water-soluble resin blended is excessive, that in Comparative Example 4 the amount of thermoplastic resin blended is excessive, and that in Comparative Example 5 a water-soluble resin other than polyvinyl alcohol is used.

[0060] (Evaluation Results of Examples 1 to 5) Comparing the evaluation results of Examples 1 to 5, only two examples, Example 2 and Example 5, received evaluation results of "◯" or "◎" for both points, and Example 5 is the most preferable embodiment.

[0061] The three examples with a "△" in the evaluation results for water resistance are Example 1, Example 3, and Example 4. It can be assumed that the reasons for the reduced water resistance in each example are that Example 1 has a low degree of saponification of polyvinyl alcohol, which makes it prone to swelling with water, Example 3 has a high blending amount of polyvinyl alcohol, which makes it susceptible to the effects of swelling with water, and Example 4 has a high amount of thermoplastic resin composition, which makes the raw material mixture less uniform.

[0062] Furthermore, in the above-described examples and comparative examples, the wood base materials do not contain harmful substances that cause sick house syndrome, such as formaldehyde, and therefore the emission of harmful substances that cause sick house syndrome, such as formaldehyde, from the inside of the wood base materials according to the above-described examples and comparative examples can be suppressed. As is clear from Table 1, it has been demonstrated that the wood substrate of the present invention has excellent mechanical strength and water resistance. [Explanation of symbols]

[0063] 10... raw material mixture, 11... wood material, 12... thermoplastic resin composition, 20... wood substrate, 30... decorative material, 31... design layer (design substrate)

Claims

1. A wood substrate comprising a wood material in at least one of powder and chip form, a thermoplastic resin composition, and a water-soluble resin, the water-soluble resin is polyvinyl alcohol having a saponification degree of 90 mol% or more, and the content thereof is within a range of 0.3 parts by mass or more and 5 parts by mass or less per 100 parts by mass of the total of the wood material and the thermoplastic resin composition; the mass ratio of the wood material to the thermoplastic resin composition (wood material / thermoplastic resin composition) is 95 / 5 to 65 / 35; The thermoplastic resin composition is a wood substrate characterized in that it contains, as thermoplastic resins, a polyethylene resin and an acid-modified polyolefin resin different from the polyethylene resin.

2. 2. The wood substrate according to claim 1, wherein the wood substrate does not contain at least one inorganic fine particle selected from the group consisting of silica, calcium carbonate, calcium magnesium carbonate, talc, and clay.

3. A wood substrate as described in claim 1 or 2, characterized in that the water-soluble resin contains only one type of polyvinyl alcohol as the polyvinyl alcohol.

4. A wood substrate comprising a wood material in at least one of powder and chip form, a thermoplastic resin composition, and a water-soluble resin, the water-soluble resin is polyvinyl alcohol having a saponification degree of 90 mol% or more, and the content thereof is within a range of 0.3 parts by mass or more and 5 parts by mass or less per 100 parts by mass of the total of the wood material and the thermoplastic resin composition; the mass ratio of the wood material to the thermoplastic resin composition (wood material / thermoplastic resin composition) is 95 / 5 to 65 / 35; The thermoplastic resin composition contains a polyethylene resin as a thermoplastic resin, The wood substrate, wherein the polyvinyl alcohol contains an acetoacetyl group.

5. A wood substrate comprising a wood material in at least one of powder and chip form, a thermoplastic resin composition, and a water-soluble resin, the water-soluble resin is polyvinyl alcohol having a saponification degree of 90 mol% or more, and the content thereof is within a range of 0.3 parts by mass or more and 5 parts by mass or less per 100 parts by mass of the total of the wood material and the thermoplastic resin composition; the mass ratio of the wood material to the thermoplastic resin composition (wood material / thermoplastic resin composition) is 95 / 5 to 65 / 35; The wood substrate, wherein the polyvinyl alcohol contains an acetoacetyl group.

6. A decorative material using a wood substrate containing a wood material in at least one of powder and chip form, a thermoplastic resin composition, and a water-soluble resin, the water-soluble resin is polyvinyl alcohol having a saponification degree of 90 mol% or more, and the content thereof is within a range of 0.3 parts by mass or more and 5 parts by mass or less per 100 parts by mass of the total of the wood material and the thermoplastic resin composition; The thermoplastic resin composition contains, as thermoplastic resins, a polyethylene resin and an acid-modified polyolefin resin different from the polyethylene resin, A decorative material characterized in that a decorative layer having a design is laminated on the wood substrate.

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