JP7174185B1 - wooden board - Google Patents

Abstract

Kind Code: A1 A wooden board As having high strength, excellent dimensional stability and surface properties, and easy to manufacture can be obtained.
SOLUTION: A wooden board As is formed by laminating a large number of small wooden flakes 1, 1, . has a thickness t of 0.05 mm or more and 0.35 mm or less, and an aspect ratio (d1/d2 ) is 1-80.
[Selection drawing] Fig. 1

Description

The present invention relates to wooden boards.

In general, as an existing wooden board, plywood made of South Sea wood such as lauan plywood is well known and widely used. However, in recent years, it has become difficult to obtain plywood made of plywood from the South Seas due to the depletion of raw materials and the prevention of environmental destruction.

Plywood made from domestic coniferous trees poses no problem in terms of raw material depletion, but its lack of surface properties limits its use to specialized strength.

OSB, PB (particle board), and MDF also pose no problem in terms of raw materials. However, although OSB has high strength, there is a problem that its surface property is insufficient. PB is inexpensive, but has a problem of insufficient strength. Although MDF has good surface properties, it does not have sufficient dimensional stability. In addition, OSB, PB, and MDF have a drawback in that their densities are higher than those of plywood made from South Sea wood.

Thus, at present, there is no wooden board that satisfies a plurality of factors such as strength, weight, surface properties, and dimensional stability in addition to the stability of raw materials.

As examples of this type of wooden board, conventionally, those shown in Patent Documents 1 to 4 have been proposed. The wood boards disclosed in Patent Documents 1 and 2 are provided with a core layer in which a large number of wooden flakes are assembled, and a surface layer laminated on at least one surface thereof and in which a large number of wooden flakes are assembled. is. In the wood board of Patent Document 1, the absolute value of the thickness of the wood flakes in the core layer is 0.50 to 1.50 mm, and the absolute value of the thickness of the wood flakes in the surface layer is 0.08 to 0.60 mm. is proposed.

On the other hand, in the technique disclosed in Patent Document 3, a fiber mat is pressure-bonded to the surface of plywood, OSB, laminated wood, or the like, and this fiber mat is compressed to produce a high-density fiber layer, thereby increasing the base material. It is used to fill in the dents on the surface.

In addition, in the decorative floor material disclosed in Patent Document 4, a moisture-proof film having a moisture permeability of 7 g/m ² for 24 hours or less is laminated on the back surface of a wooden base material such as MDF. Even if a low decorative sheet is attached, warping and bending due to the magnitude of dimensional change are suppressed.

JP-A-7-47514 JP-A-7-76004 JP 2019-31104 A JP 2019-107894 A

However, in the wood boards shown in Patent Documents 1 and 2, not only the size of the wood flakes constituting the wood board but also the thickness of the surface layer and the core layer are different. It is necessary to prepare different types of wood flakes, which inevitably requires time and effort for manufacturing and management. In addition, the wooden board using the wooden flakes described in the above patent document has unevenness on the surface, and cannot ensure the surface smoothness that can be used as, for example, a base material for floors.

In addition, the wooden board of Patent Document 3 not only requires time and effort to secondary process the base material, but also has a double structure of the base material and the fiber layer, so it is possible to reduce the thickness of the board. There are limits. In addition, it is not possible to suppress dimensional change due to moisture absorption.

Furthermore, in the decorative material of Patent Document 4, the secondary processing of the base material is not only time-consuming, but also the width of the base material that can be used is restricted by the width of the moisture-proof film.

The present invention has been made in view of these points, and its object is to improve the wood board structure in which a large number of wood flakes are laminated, thereby achieving high strength, excellent dimensional stability and surface properties, and a manufacturing method. To obtain a wooden board (base material) which is easy to obtain.

In order to achieve the above object, the present invention uses wood flakes whose size including thickness is limited to a very small range in contrast to cutting pieces that are commonly used as OSB constituent materials. Small wooden flakes of which the size is further limited to a minute range are used as constituent materials, and a large number of the small wooden flakes are laminated in an aggregated state to form a wooden board.

In the present invention, the core layer and the front and back layers are integrally laminated on the front and back surfaces of the wooden board by laminating and integrating the wooden material layers composed of the small wooden flakes whose size is further limited to a minute range. A wooden laminated board with

In this specification, the term "cut piece" refers to a piece cut from raw wood for OSB, and is commonly used as a constituent material of OSB. The "woody flake" according to the present invention is cut from raw wood in the same way as the "cut piece", but refers to a thin piece that is outside the normal thickness range of the "cut piece" and smaller than that. . The "woody flakes" according to the present invention refer to flakes smaller than the "woody flakes" within the same thickness range as the "woody flakes".

Specifically, the first invention is directed to a wooden board in which a large number of small wooden flakes having front and back surfaces along the fiber direction are laminated together and bonded together. The wooden flakes constituting the wooden board have a thickness between the front and back surfaces of 0.05 mm or more and 0.35 mm or less, and the first length along the fiber direction / the fiber orthogonal direction orthogonal to the fiber direction characterized by an aspect ratio defined by the second length along the .

In the first invention, the wooden board is formed by bonding and integrating a large number of small wooden flakes having a thickness of 0.05 mm or more and 0.35 mm or less and an aspect ratio of 4 2 to 80, which are laminated in an aggregated state. The thickness, the first length and the second length of the wood flakes are all average values.

Specifically, the wood board is produced by pulverizing wood flakes having a specific thickness obtained in step P1 described later in a first direction of the wood flakes and in a second direction orthogonal to the first direction in step P2 also described later. It consists of small wooden flakes of only one size, and the thickness of the small wooden flakes is extremely thin. Variation in thickness is small and uniform thickness is obtained. In addition, since the aspect ratio defined by the average first length/average second length of the small wood flakes is also within a certain range, the wooden board is made up of small wooden flakes having a uniform shape within a certain range. become something. As a result, not only does the strength of the wood board increase, but warpage due to moisture absorption and desorption is less likely to occur, and good dimensional stability comparable to that of plywood made of South Sea wood can be obtained. In addition, since a large number of small wooden flakes are uniform in thickness and shape, the surface of the wooden board does not have large irregularities unlike ordinary OSB, and the wooden board has excellent surface properties. In addition, since a large number of small wooden flakes of uniform size are collected and laminated, the production thereof is facilitated.

A second invention is the wooden board according to the first invention, wherein the wooden flakes have a thickness of 0.15 mm or more and 0.25 mm or less and an elongated shape with an aspect ratio of 4 to 40. Characterized by This further improves the dimensional stability and surface properties of the wooden board.

A third invention is characterized in that in the wooden board of the first invention, the area of the front and back surfaces of the wooden flakes is 6 cm ² or less. This further improves the dimensional stability and surface properties of the wooden board.

A fourth aspect of the invention is directed to a laminated wood board obtained by laminating and integrating wooden material layers on the front and back surfaces of the wood board according to the first invention. The wood material layers constituting the front and back layers of this wood laminate board are characterized in that the wood micro flakes having an area smaller than that of the wood flakes are laminated together and bonded together. In addition, an area means the numerical value which multiplied the 1st length and the 2nd length, and means the area of the front and back surface along a fiber direction.

In the fourth aspect of the invention, the wood laminate board is formed by laminating and integrating the wood board forming the core layer and the wood material layers forming the front and back layers. The wooden material layer is formed by laminating a large number of microscopic wooden flakes having an area smaller than that of the small wooden flakes and bonding them together.

In this way, the wood laminate board is produced by pulverizing wood flakes having a specific thickness obtained in the step P1 described later in the first and second directions of the wood flakes in the steps P2 and P6, which will also be described later. It consists of small wooden flakes. Since the wood laminate board has a wood board composed of small wood flakes in the core layer, it exhibits the same effects as the wood board of the first invention. Furthermore, in the wood laminate board, a wood material layer composed of a large number of small wood flakes having a smaller area than the small wood flakes is laminated on both sides of the wood board to form the front and back layers. Large unevenness does not occur on the surface of the sheet, and the surface properties can be further improved, resulting in excellent surface properties similar to MDF. In addition, the wood laminate board includes an assembly of a large number of evenly sized wooden microflakes, an assembly of a large number of uniformly sized wooden small flakes, and an assembly of woody microflakes. are laminated and integrated in order, the manufacture thereof becomes easy.

A fifth invention is the wooden board (laminated wood board) according to the fourth invention, wherein the ratio of the thickness of each wooden material layer to the whole wood board (laminated wood board) is 5% or more and 40% or less. Characterized by This makes it possible to achieve both strength and surface properties of the wood laminate board.

A sixth invention is characterized in that the wooden board of any one of the first to fifth inventions has a density of 500 kg/m ³ or more and 800 kg/m ³ or less. This further increases the strength of the wooden board.

A seventh invention is the wooden board according to any one of the first to fifth inventions, wherein the root mean square height Sq of the surface is 0.005 μm or more and 0.015 μm or less, or the arithmetic mean height Sa of the surface is 0.005 μm or more and 0.015 μm or less. 002 μm or more and 0.007 μm or less. This further improves the surface properties of the wooden board. In this specification, the surface property of a wooden board refers to the surface property of a wooden board adjusted to the product thickness with, for example, a #150 sander.

As described above, according to the present invention, a wooden board is formed by laminating a large number of small wooden flakes having front and back surfaces along the fiber direction and bonding and integrating them. By setting the length to 0.05 mm or more and 0.35 mm or less and the aspect ratio defined by the first length/second length to be 1 to 80, the large number of small wooden flakes are uniform in size with little variation. As a result, it is possible to increase the strength of the wood board, and obtain good dimensional stability and surface properties comparable to those of plywood made of plywood made of plywood of the South Seas, so that the wood board can be easily manufactured.

FIG. 1 is a cross-sectional view of a wooden board according to a first embodiment of the present invention. FIG. 2 is an enlarged cross-sectional view of the waist of the wooden board according to the first embodiment. FIG. 3 is an enlarged perspective view schematically showing small wooden flakes constituting the wooden board according to the first embodiment. FIG. 4 is a diagram showing the manufacturing process of the wooden board according to the first embodiment. FIG. 5 is an enlarged cross-sectional view showing a state in which the wooden board according to the first embodiment is hot-pressed from a mat that is an aggregate of small wooden flakes. FIG. 6 is a diagram showing the characteristics of the wooden board according to the first embodiment in comparison with boards made of other materials. FIG. 7 is a cross-sectional view of a wooden board according to a second embodiment of the present invention. FIG. 8 is an enlarged cross-sectional view of a main part of a wooden board according to the second embodiment. FIG. 9 is an enlarged perspective view schematically showing a wooden microflake forming a wooden material layer according to the second embodiment. FIG. 10 is a diagram showing the manufacturing process of the wooden board according to the second embodiment. FIG. 11 is an enlarged cross-sectional view showing a state in which the wooden board according to the second embodiment is hot-pressed from the mat, which is an aggregate of the small wooden flakes and the very small wooden flakes. FIG. 12 is a diagram showing the characteristics of the wooden board according to the second embodiment in comparison with boards made of other materials.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail based on the drawings. The following descriptions of the embodiments are merely exemplifications in nature, and are not intended to limit the invention, its applications, or its uses at all.

[First embodiment]
<wood board>
FIG. 1 shows a wooden board As according to a first embodiment of the present invention. For example, the wooden board As has a density of 500 kg/m ³ or more and 800 kg/m ³ or less and a thickness of 3 mm or more and 12 mm or less. Thin type wooden board As with a thickness of 3 mm or more and less than 6 mm is, for example, an inner wall material for a loading platform used for a loading platform of a vehicle such as a truck, a base material for a cushion floor installed indoors, a decorative surface material, an interior building material (riser It is constructed as an interior material such as a board, etc. A medium-thickness type wooden board As having a thickness of about 6 mm or more and 12 mm or less is used, for example, as a soundproof floor base material, a floor base material for shoes, an entrance fixture, and the like. In this way, the wooden board As is used as a substitute material for existing plywood for baseboards. This wooden board As will be described in detail.

As shown in an enlarged view in FIG. 2, the wooden board As is formed by laminating a large number of small wooden flakes 1, 1, . The wood flakes 1, 1, . . . have one kind of thickness.

To explain the small wooden flakes 1, as shown in an enlarged view in FIG. It is preferably 0.15 mm or more and 0.25 mm or less, more preferably 0.15 mm or more and 0.20 mm or less. The characteristics of the wooden board As are determined by the flakes 1, 1, . . . of the thin thickness t. The thickness t of the wooden flakes 1 is an average value. In other words, the small wooden flakes 1 are strands (also referred to as cut pieces in the present invention) that are used as elements (constituent materials) of ordinary OSBs, and generally have a thickness of about 0.6 mm to 1.5 mm. , whereas it is a flake with a thinner thickness than that.

In addition, the wooden flakes 1 have an average length d1 as a ratio of the average value of the first length d1 along the first direction to the average value of the second length d2 along the second direction orthogonal to the first direction. The aspect ratio (d1/d2) defined by 1 length d1/average second length d2 is 1-80. In other words, the small wooden flakes 1 may be square-shaped or long and narrow (strip-shaped). When the wood flakes 1 have an elongated shape, the first length d1 is the longitudinal dimension (length), and has fibers 1a, 1a, . is the fiber direction dimension of Also, the second length d2 is the dimension in the transverse direction (width), for example, the dimension in the direction orthogonal to the fiber direction along the direction orthogonal to the fiber direction. The aspect ratio is preferably 2-70, more preferably 3-55, even more preferably 4-40. As will be described later, although not shown, the small wood flakes 1 are wood flakes that have been cut from raw wood (also referred to as wood flakes after cutting) and are crushed to become smaller than the wood flakes. In the sense of defining something different from wood flakes, the wood flakes after cutting are referred to as "small wood flakes."

The area of the front and back surfaces of the wooden flakes 1 (value obtained by multiplying the first length d1 and the second length d2) is preferably 64 cm ² or less, more preferably 32 cm ² or less, and even more preferably. is 16 cm ² or less, more preferably 6 cm ² or less. Also, the lower limit of the area is, for example, 0.5 cm ² or more.

The species of wood used for the small wooden flakes 1, 1, . . . is not particularly limited. For example, there are fir materials such as cedar, cypress, Douglas fir, etc., acacia, aspen, poplar, pine (hard pine, soft pine, radiata pine, etc.), birch, rubber (rubber tree), etc., but are limited to these tree species. In addition, various tree species can be used. Various tree species include Todomatsu, Japanese larch, Ezo spruce, Sawara, Hiba, Kaya, Japanese hemlock, Maki, various pine, paulownia, maple, birch (white birch), vertebrate, beech, oak, fir, oak, oak, camphor, zelkova. Japanese timber such as American cypress, rice cypress, rice cedar, rice fir, spruce, hemlock, redwood, etc., agathis, terminalaria, lauan, meranti, juncon, chamelele, kalampayan, Amberoi, melina, teak, apiton Any material can be used, such as South Sea timber such as sengonglaut, balsa, cedro, mahogany, lignum vita, acacia manguum, Mediterranean pine, bamboo, sorghum, and chamelele.

Regarding the physical properties of the wooden flakes 1, the density is preferably 250 kg/m ³ or more, more preferably 300 kg/m ³ or more, more preferably 800 kg/m ³ or less, more preferably 500 kg/m ³ or less, and still more preferably. is 400 kg/m ³ or less. If the density is less than 250 kg/m ³ , the thickness of the mat required to form the wood board As with the same density and strength is increased, and the press pressure related to the hot press treatment in the press molding process is increased. need to raise.

Although the density of the small wooden flakes 1 may exceed 800 kg/m ³ , it is difficult to obtain such small wooden flakes 1 easily. That is, the upper limit of the density is not limited to 800 kg/m ³ and may be a higher value as long as the small wood flakes 1 exceeding 800 kg/m ³ can be easily obtained.

Also, the moisture content of the small wooden flakes 1 is preferably about 2 to 20%, more preferably 2 to 8%. If the water content is less than 2%, softening takes a long time in the hot press treatment in the press molding process, and the pressing time becomes long, which may reduce the strength.

Moreover, if the moisture content of the small wooden flakes 1 exceeds 20%, it takes time to heat and compress in the same hot-pressing process, and there is a risk that the hardening of the adhesive will be hindered and the strength will decrease. .

In the wooden board As, the fiber direction (longitudinal direction) along the fibers 1a, 1a, . . . of the many small wooden flakes 1, 1, . The orientation of the fiber direction is not essential, and the fiber direction may be randomly oriented. The fiber direction (longitudinal direction) being oriented in the reference direction means that the fibers 1a, 1a, . . . of all the small wooden flakes 1, 1, . In other words, the fiber directions of the oriented wooden flakes 1, 1, . . . are parallel to each other. Some of the small wooden flakes 1, 1, . . . may include small wooden flakes 1, 1, .

<Manufacturing method of wooden board>
Next, a method for producing the small wooden flakes 1 and a method for producing the wooden board As from the small wooden flakes 1 will be described with reference to FIG. The method for manufacturing the wooden flakes 1 includes a wooden flake manufacturing step P1 and a wooden flake manufacturing step P2. The manufacturing method of wooden board As further includes the subsequent adhesive application step P3, mat forming step P4, and hot pressing step P5.

(Wood flake manufacturing process P1)
If necessary, raw wood such as logs and thinned wood are cut short and the bark is removed. If necessary, the moisture content is adjusted, and cutting equipment (strander) with outer or inner blade to form a large number of thin wood flakes (wood flakes after cutting) that are thinner and smaller than the cut pieces normally used as the constituent material of OSB. It can also be formed from offcuts, waste materials, and waste pallet materials generated at construction sites and the like. A common cutting device is used. The thickness of the wood flakes is adjusted by the speed at which the raw wood is fed into the cutting machine. The wooden flakes formed by this cutting (the wooden flakes after cutting) are different from the small wooden flakes 1 constituting the wooden board As of the present embodiment, and have a larger area (specifically, the length in the direction perpendicular to the fiber ) is large.

At this time, each wood flake is cut so that the fibers appear linearly on the front and back surfaces, and the cut thickness is the thickness t of the small wood flake 1 . This is because, in subsequent steps, the thickness t of the small wooden piece 1 basically does not change from the thickness of the wooden piece after cutting, and the thickness of the wooden piece after cutting becomes the thickness t of the small wooden piece 1 as it is. be.

The wood flakes after cutting obtained in this step P1 are passed through a sieve (for example, a mesh of Φ5 mm or more) or the like to sort (classify) the size of the wood flakes after cutting (classification step) to obtain the next wood flakes. In some cases, wooden flakes having a size comparable to the small wooden flakes 1, 1, . be. In that case, the wooden flakes can be used in the adhesive application step P3 as the small wooden flakes 1, 1, . . . without being subjected to the small wooden flake manufacturing step P2.

(Wood flake manufacturing process P2)
After the above cutting, the wood flakes classified as necessary (wood flakes after cutting) are pulverized using a grinder such as a hammer mill, a pin mill, or a jet mill that does not use blades, a knife flaker, a cutter mill, or the like. The wood flakes 1, 1, . . . composing the wood board As are formed by pulverizing the wood flakes to a size smaller than that of the wood flakes immediately after cutting in the direction perpendicular to the fibers. At this time, when the wooden flakes after cutting are pulverized in the width direction so as to split along the fiber direction (longitudinal direction), elongated small wooden flakes 1, 1, . . . can be produced. In other words, if a force (impact) is applied along the fiber-perpendicular direction to the wood flake after cutting, it is difficult to break, but if a force is applied parallel to the fiber direction, the wood flakes are easily broken. Even if the wooden flakes are curled after cutting, they are divided into flat pieces by pulverizing them. The direction of the force applied to the wooden flake after cutting is not limited to the direction parallel to the fiber direction. When a force is applied in random directions to the wood flake after cutting, the wood flake after cutting usually cracks from the portion where the force is weaker (easier to crack in the direction where the force is weaker). The force that connects the fibers of the wood flakes after cutting (the force in the direction perpendicular to the fibers) is overwhelmingly weaker than the force in the direction of the fibers. (When a force is applied), after cutting, the wooden flakes are split along the fiber direction and shortened in the direction orthogonal to the fibers, and elongated small wooden flakes 1, 1, . . . are obtained.

Further, even if there are wood knots in the wood thin piece after cutting, the knots are more fragile than the other portions, so the knots are pulverized into powder and removed in the subsequent classification process.

In the case of a grinder that uses a knife, there is a risk that the wooden flakes will be unintentionally pulverized in the direction perpendicular to the fiber after cutting. It is preferable to pulverize the wooden flakes after cutting using a pulverizer that does not use a blade.

In this way, instead of a one-step cutting process, by adding a crushing process after that and going through a two-step process, the cut wood flakes that are thinner and smaller than the cut pieces are cut into knots of the required size. High-strength wooden flakes 1, 1, . . . without parts can be easily manufactured.

A classification step of passing the small wood flakes 1, 1, ... obtained in the pulverization step through a sieve or the like to select (classify) the size of the small wood flakes 1, 1, ... may be included. As a result, the large number of small wooden flakes 1, 1, . . . are finer and uniform in size and shape. The small wooden flakes 1 are manufactured as described above.

(Adhesive application step P3)
In the small wooden flake manufacturing process P2, when a large number of small wooden flakes 1, 1, . , 1, . As the adhesive, for example, an isocyanate-based adhesive can be used, and in addition, for example, an amine-based adhesive such as a phenol resin, a urea resin or a melamine resin, or a natural product (tannin)-based adhesive for wood may be used. . Also, a commonly used water repellent agent may be used together with the adhesive.

(Mat forming step P4)
Next, as shown on the left side of FIG. 5, a large number of small wooden flakes 1, 1, . A mat A1 of small wooden flakes 1, 1, . . . For example, when forming a wooden board As having a thickness of 4 mm, the small wooden flakes 1, 1, and 1 having a thickness t of 0.2 mm are arranged so that the thickness (height) of the mat A1 is about 40 mm. pile up.

(Thermal pressing process P5)
The mat A1 is carried into a hot press device and set between hot plates, and the mat A1 is subjected to hot press processing at a predetermined pressure and temperature by the hot press device to be compressed, and then integrated by curing the adhesive. to mold. Thus, the wooden board As shown in FIG. 1 is formed.

At this time, as shown in FIG. 5, the exemplified mat A1 having a thickness of about 40 mm is compressed into a wooden board As having a thickness of 4 mm, for example, and the thickness is compressed to 1/10. The pressing temperature for hot pressing is not particularly limited, but is, for example, 100 to 180.degree. The press pressure for the hot press treatment is, for example, 2 to 4 N/mm ² and the press time is, for example, 1 to 2 minutes. The pressing time varies depending on the thickness of the wood board As, and may be completed in less than 1 minute or may be completed in 2 minutes or more. Also, a preliminary heat treatment using a heating device may be performed before the hot pressing treatment using the hot pressing device.

In addition, since the small wooden flakes 1, 1, . There is no variation in the strength of the wooden board As. In other words, in a strand board using large strands (cutting pieces), for example, an uneven mat including knots causes thin and low-strength portions partially (spots), resulting in variations in strength, but this is eliminated. Moreover, the thinner the wooden flakes 1, 1, . In general, a strand board using large strands (cutting pieces) can increase the strength. It serves both the homogeneity and strength of the board As.

Furthermore, the small wooden flakes 1, 1, . Even if the small wooden flakes 1, 1, . . . contain a relatively large amount of moisture, even if they are hot-pressed, steam generated by the evaporation of the moisture smoothly escapes from the mat A1. That is, as shown on the left side of FIG. 5, a large number of minute voids exist between the mutually adjacent wooden flakes 1, 1, . . . in the mat A1. The voids communicate not only in the fiber direction and fiber orthogonal direction of the small wooden flakes 1, 1, . . . but also in the thickness direction, and are three-dimensionally continuous. Therefore, punctures are less likely to occur when pressurization of the wooden board As is stopped.

Through these steps, a wooden board As having a density of 500 kg/m ³ or more and 800 kg/m ³ or less and a bending Young's force of 3.5 GPa or more and 7.0 GPa or less is formed. As shown in the right side of FIG. 5, this wooden board As has (remains) a large number of three-dimensionally continuous minute voids therein. Therefore, wooden board As is also excellent in air permeability.

(Other processes)
The manufacturing method of the wooden board As includes, as another process, after the hot pressing process P5, the wooden board As is cured to the equilibrium moisture content, and then the front and back surfaces are ground with a sander to adjust the final thickness. You may have A commonly used sander can be used, for example, #150 sander. Through this finishing process, a wooden board As having even better surface properties can be obtained.

<Surface properties of wood board>
The wooden board As preferably has a surface root mean square height Sq of 0.005 μm or more and 0.015 μm or less, or an arithmetic mean surface height Sa of 0.002 μm or more and 0.007 μm or less. The surface of the wooden board As refers to the surface of the wooden board As after the finishing process, for example, the surface of the wooden board As adjusted to the product thickness with a #150 sander. The root-mean-square height Sq and the arithmetic mean height Sa are surface roughness parameters representing the surface properties defined in ISO25178. That is, the wooden board As has excellent surface properties by controlling the parameters Sq and Sa, which specify the surface properties, within specific ranges.

The root-mean-square height Sq is a parameter corresponding to the standard deviation of the distance from the average plane, and corresponds to the standard deviation of height. Therefore, the smaller the value of the root-mean-square height Sq on the surface of the wooden board As, the smaller the variation in the size of the irregularities on the surface, and the better the surface properties. Specifically, if the thickness t of the small wooden flakes 1, 1, . . . If the thickness t of the wooden flakes 1, 1, ... is 0.25 mm or less (preferably 0.20 mm or less), the root mean square height Sq of the surface of the wooden board As is 0.005 μm or more and 0.008 μm or less. Since the surface roughness of As is comparable to that of MDF, which has excellent surface properties, the wood board As has even better surface properties and is preferable.

The arithmetic mean height Sa represents the mean of the absolute values of the height differences of each point with respect to the mean plane of the surface. Therefore, the smaller the value of the arithmetic mean height Sa on the surface of the wooden board As, the less large unevenness the surface has, and the better the surface properties. Specifically, if the thickness t of the small wooden flakes 1, 1, . . . If the thickness t of the small flakes 1, 1, . . . , the surface roughness of which is comparable to that of MDF, which has excellent surface properties. Therefore, wooden board As has even better surface properties and is therefore preferable.

The surface properties of the wooden board As are not limited to the root-mean-square height Sq and the arithmetic mean height Sa. It may be specified by the maximum height Sz indicating the sum, kurtosis Sku, or the like.

Therefore, the wood board As of the above embodiment can have the following effects.

The wood board As has an extremely thin thickness t, the average value of which is 0.05 mm or more and 0.35 mm or less, and the average value of the first length d1 along the first direction (fiber direction) and the second direction Ratio to the average value of the second length d2 along the (fiber orthogonal direction): the aspect ratio (d1/d2) defined by the average first length d1/average second length d2 is 1 to 80 A large number of small wooden flakes 1, 1, . . .

That is, the single-layer wooden board As is composed of only one type of small wooden flakes 1, 1, ..., and the thickness t of the small wooden flakes 1, 1, ... is extremely thin, 0.05 mm to 0.35 mm. Since the thickness is within the narrow range, the thickness t of the large number of small wooden flakes 1, 1, . . . In addition, since the aspect ratio (d1/d2) of the small wooden flakes 1, 1, . . . homogenous. As a result, not only is the strength of the wooden board As increased, warping due to moisture absorption and desorption is less likely to occur, and good dimensional stability comparable to that of plywood made of South Sea wood can be obtained. In addition, since a large number of small wooden flakes 1, 1, . It becomes a thing. In addition, since a large number of small wooden flakes 1, 1, .

In particular, the average value of the thickness t of the small wooden flakes 1, 1, . . . , the dimensional stability and surface properties of the wood board As are further improved.

FIG. 6 exemplifies the characteristics of the wooden board As according to the present invention in comparison with boards made of other materials. It is as large as lauan plywood, and is superior to lauan plywood in terms of anisotropy in dimensional stability and color tone and color uniformity in terms of surface properties. In addition, compared to OSB, the wood board As has uniform bending Young in the vertical and horizontal directions, and is excellent in anisotropy in dimensional stability, smoothness in surface properties, and color tone/color uniformity. That is, the wooden board As has high strength and excellent dimensional stability and surface properties.

[Second embodiment]
<Wood Board (Laminated Wood Board)>
FIG. 7 shows a wooden board Am according to a second embodiment of the present invention. The wooden board Am according to the present embodiment is obtained by laminating and integrating wooden material layers on the front and back surfaces of the wooden board As according to the first embodiment, and can be called a laminated wood board. Hereinafter, the wood board Am is also referred to as a wood laminate board Am. The configuration of the wooden board As, other than the wooden material layers forming the wooden laminated board Am, is the same as that of the first embodiment, so detailed description thereof will be omitted here. Also, the same reference numerals are assigned to the same components as in the first embodiment, and the description thereof will be omitted.

The wood laminate board Am used has, for example, a density of 500 kg/m ³ or more and 800 kg/m ³ or less and a thickness of 3 mm or more and 12 mm or less. The thin type laminated wood board Am with a thickness of 3 mm or more and less than 6 mm is used, for example, as an inner wall material for a loading platform of a vehicle such as a truck, a base material for a cushion floor installed indoors, a decorative surface material, an interior building material ( It is constructed as an interior material such as a riser board, etc.). A medium-thickness type laminated wood board Am having a thickness of about 6 mm or more and 12 mm or less is used as, for example, a soundproof floor base material, a floor base material for shoes, an entrance fixture, and the like. Thus, the wood laminate board Am is used as a substitute material for the existing plywood for baseboards. In addition, since the wood laminate board Am has surface properties similar to those of MDF, it can be suitably used for decorative thin plywood.

The wooden laminated board Am includes a first wooden material layer B and two wooden material layers (hereinafter also referred to as “second wooden material layers”) C, C. The material layers C, C are laminated and integrated. In other words, the first wooden material layer B is interposed between the two second wooden material layers C,C. That is, the first wooden material layer B constitutes the core layer of the laminated wooden board Am, and the two second wooden material layers C, C constitute the front and back layers of the laminated wooden board Am.

The ratio of the thickness of each second wooden material layer C to the whole wooden laminated board Am is preferably 5% or more and 40% or less, more preferably 8% or more and 30% or less, further preferably 10% or more and 25% or less. be. That is, the second wooden material layer C:first wooden material layer B:second wooden material layer C in the wooden laminated board Am is preferably 5:90:5 to 40:20:40, more preferably 8:84: 8-30:40:30, more preferably 10:80:10-25:50:25. By appropriately changing the thickness ratio between the first wooden material layer B and each of the second wooden material layers C, it is possible to obtain a wood laminated board Am that has both the required strength and excellent surface properties depending on the application. .

(First wooden material layer)
The first wooden material layer B is composed of the wooden board As according to the first embodiment, as described above. That is, the first wooden material layer B is applied with all the configurations described for the wooden board As.

(Second wooden material layer)
The second wooden material layer C, as shown in an enlarged view in FIG. 8, is formed by bonding and integrating a large number of microscopic wooden flakes 2, 2, . , a large number of wood microflakes 2, 2, . . . have one kind of thickness.

The small woody flakes 2 are flakes smaller in size (areas of the front and back surfaces thereof) than the small woody flakes 1 . To explain in detail the microscopic wood flakes 2, as shown in an enlarged view in FIG. 0.30 mm or less, more preferably 0.15 mm or more and 0.25 mm or less, and still more preferably 0.15 mm or more and 0.20 mm or less. In other words, the thickness t of the small wooden flakes 2 is equal to or smaller than the thickness t of the small wooden flakes 1 . Thus, the characteristics of the second wooden material layer C, that is, the characteristics of the laminated wood board Am are determined by the small wooden flakes 2, 2, . . . having the thin thickness t. The thickness t of the wooden microflakes 2 is an average value.

The aspect ratio (d1/d2) of the wooden microflakes 2, which is defined similarly to the wooden microflakes 1, is preferably 1-500. In other words, the woody microflakes 2 may be square or long and narrow (rectangular). When the woody microflakes 2 have an elongated shape, the first length d1 is the longitudinal dimension (length) as in the case of the woody microflakes 1, and has fibers 2a, 2a, . , is the fiber direction dimension in the direction along the fiber 2a. Also, the second length d2 is the dimension in the transverse direction (width), for example, the dimension in the direction orthogonal to the fiber direction along the direction orthogonal to the fiber direction. The aspect ratio is preferably 2-100, more preferably 3-12.5, even more preferably 5-10.

The area of the front and back surfaces of the wooden microflakes 2 is not particularly limited as long as it is smaller than the area of the front and back surfaces of the small wooden flakes 1, but it is preferably 5 cm ² or less, more preferably 2 cm ² or less, and even more preferably. is 1 cm ² or less, more preferably 0.5 cm ² or less.

The species of wood used for the microscopic wood flakes 2, 2, . . . is not particularly limited. . Moreover, the species of wood of the microscopic wood flakes 2, 2, . . . may be the same as or different from the species of wood of the small wood flakes 1, 1, . From the viewpoint of easily producing the woody microflakes 2, 2, ... using the small woody flakes 1, 1, ..., the tree species of the woody microflakes 2, 2, ... is the same as the woody flakes 1, 1, ... preferably the same.

With respect to the physical properties of the wooden microflakes 2, the density is preferably 250 kg/m ³ or more, more preferably 300 kg/m ³ or more, and preferably 800 kg/m ³ or less, more preferably 500 kg/m ³ or less, and even more preferably. is 400 kg/m ³ or less. When the density is less than 250 kg/m ³ , the thickness of the mat required to form the wood laminate board Am with the same density and strength increases, and the press pressure related to the hot press treatment in the press molding process increases. need to be increased.

Although the density of the woody microflakes 2 may exceed 800 kg/m ³ , it is difficult to obtain such woody microflakes 2 easily. That is, the upper limit of the density is not limited to 800 kg/m ³ and may be a higher value as long as the wood microflakes 2 exceeding 800 kg/m ³ can be easily obtained.

Also, the moisture content of the wood microflakes 2 is preferably about 2 to 20%, more preferably 2 to 8%.

In the second wooden material layer C, even if the fiber direction (longitudinal direction), which is the direction along the fibers 2a, 2a, . However, the orientation of the fiber direction is not essential, and the fiber direction may be randomly oriented. The woody micro flakes 2, 2, .

<Method for producing wooden board (laminated wooden board)>
Next, a method for manufacturing the small wooden flakes 1, 1, . . . and the extremely small wooden flakes 2, 2, . . The manufacturing method of the wooden flakes 1, 1, . . . has a wooden flake manufacturing step P1 and a wooden flake manufacturing step P2. The manufacturing method of the wooden micro flakes 2, 2, . . . further includes the subsequent wood micro flake manufacturing step P6. The manufacturing method of the wooden laminate board Am further includes an adhesive application step P3, a mat forming step P4, and a hot pressing step P5.

(Wood flake manufacturing process P1)
The wooden flake manufacturing process P1 is the same as the wooden flake manufacturing process P1 according to the first embodiment, and thus detailed description thereof is omitted here. In the subsequent steps, the thickness t of the small wood flakes 1 and the very small wood flakes 2 basically does not change from the thickness of the wood flakes after cutting, and the thickness of the wood flakes after cutting remains as it is. The thickness of the woody microflake 2 is t.

(Wood flake manufacturing process P2)
Since the small wooden flake manufacturing process P2 is also the same as the small wooden flake manufacturing process P2 according to the first embodiment, detailed description thereof will be omitted here.

(Woody ultra-thin piece manufacturing process P6)
From the small wooden flakes 1, 1, . Small wooden flakes 2, 2, . . . smaller than the small wooden flakes 1, 1, . The small wooden flakes 3 removed in the above classification step refer to small wooden flakes other than the small wooden flakes 1 formed in the small wooden flake manufacturing step P2, and the size of the small wooden flakes 1 (thickness t and At least one aspect ratio) is out of range.

Specifically, the small wooden flakes 1, 1, . . . and/or the small wooden flakes 3, 3, . . . and/or the small wood flakes 3, 3, . Compared with the flakes 1, 1, . That is, the wooden micro flakes 2 are smaller than the wooden micro flakes 1 in the second length (width) d2. Further, in the further pulverizing step in the manufacturing process P3, the small wooden flakes 1, 1, . . . and/or the small wooden flakes 3, 3, . As a result, the wooden micro flakes 2 are smaller than the wooden flakes 1 in not only the second length (width) d2 but also the first length d1.

As another method, the small wooden flakes 3, 3, . . .

Thus, by using the small wooden flakes 1, 1, ... formed in the small wooden flake manufacturing process P2 and the small wooden flakes 3, 3, ... removed, these small wooden flakes 1, 3, ... are crushed. By further passing through the step of classifying or classifying, the small wooden flakes 2, 2, . It can be manufactured easily.

Obtained in the further pulverization step may be passed through a sieve or the like (for example, a Φ2 mesh) to screen (classify) the very small wood flakes 2, 2, . As a result, the large number of microscopic woody flakes 2, 2, . . . are fine and uniform in size and shape. As described above, the wood micro flakes 2, 2, . . . are manufactured.

(Adhesive application step P3)
In the small wood flake manufacturing process P2 and the wood micro flake manufacturing process P6, a large number of small wood flakes 1, 1, ... and wood micro flakes 2, 2, ... fine and uniform in size and shape are obtained by sorting. Then, an adhesive application step P3 is performed, and the small wooden flakes 1, 1, . . . and the very small wooden flakes 2, 2, . As the adhesive, for example, an isocyanate-based adhesive can be used, and in addition, for example, an amine-based adhesive such as a phenol resin, a urea resin or a melamine resin, or a natural-based adhesive may be used. Also, a commonly used water repellent agent may be used together with the adhesive.

(Mat forming step P4)
Next, as shown on the left side of FIG. 11, first, a large number of wood microflakes 2, 2, . By laminating (stacking) them up to a predetermined thickness (height) in this state, a mat C1 (second aggregate) composed only of the wooden microflakes 2, 2, . . . is formed. Subsequently, on the formed mat C1, a large number of small wooden flakes 1, 1, . By stacking them up to a predetermined thickness, a mat B1 (first assembly) composed only of the small wooden flakes 1, 1, . . . is formed. Finally, on the formed mat B1, a mat C1 composed only of the wooden microflakes 2, 2, . . . is formed in the same manner as described above. By laminating the mat C1, the mat B1 and the mat C1 in this order, the laminated mat A1 having a three-layer structure is formed.

At this time, the thicknesses of the mat B1 and the mat C1 are adjusted so that the ratio of the thickness of the first wooden material layer B and each of the second wooden material layers C to the entire wooden laminated board Am is set to a desired ratio. For example, the ratio of the thickness of each second wooden material layer C to the whole laminated wood board Am is 15% (second wooden material layer C: first wooden material layer B: second wooden material layer C=15:70: 15) In order to form a wood laminate board Am with a thickness of 4 mm, first, the thickness t is set to 0.2 mm so that the thickness (height) of the mat C1 is about 5 mm. 2, 2, . . . are piled up. Subsequently, the small wooden flakes 1, 1, . . . having a thickness t of 0.2 mm are stacked on the mat C1 so that the mat B1 has a thickness of about 24 mm. Finally, the micro-wood flakes 2, 2... are stacked on the mat B1 so that the mat C1 has a thickness of about 5 mm. Thus, the thickness (height) of the laminated mat A1 having a three-layer structure composed of the mats C1, B1 and C1 is about 34 mm.

(Thermal pressing process P5)
The laminated mat A1 is first pressed and compacted a little like an ordinary wooden board, and then carried into a hot press and set between hot plates. The laminated mat A1 is subjected to hot press processing at a predetermined pressure and temperature by a hot press device, and is compressed, and the adhesive is cured to integrally mold it. As a result, the wood laminate board Am shown in FIG. 7 is formed.

At this time, as shown in FIG. 11, the laminated mat A1 having a thickness of about 40 mm as exemplified above is compressed into a wooden laminated board Am having a thickness of, for example, 4 mm, and the thickness is compressed to 1/10. The pressing temperature for hot pressing is not particularly limited, but is, for example, 100 to 180.degree. The press pressure for the hot press treatment is, for example, 2 to 4 N/mm ² and the press time is, for example, 1 to 2 minutes. The pressing time varies depending on the thickness of the wood laminate board Am, and may be completed in less than 1 minute or may be completed in 2 minutes or more. Also, a preliminary heat treatment using a heating device may be performed before the hot pressing treatment using the hot pressing device.

In addition, the small wood flakes 1, 1, ... and the smaller wood flakes 2, 2, ... have their knots removed and are kept within a fine range without variation. Being drooped, mats B1 and C1 are each homogenous. In other words, the entire laminated mat A1 becomes homogeneous, thereby eliminating variations in the strength of the wooden laminated board Am. In other words, in a strand board using large strands (cutting pieces), for example, an uneven mat including knots causes thin and low-strength portions partially (spots), resulting in variations in strength, but this is eliminated. Moreover, the thinner the wooden flakes 1, 1, . In general, a strand board using large strands (cutting pieces) can increase the strength. It serves both the homogeneity and the strength of the laminated board Am.

Further, the small wooden flakes 1, 1, . . . are small and uniform in size, and gaps are uniformly formed between the small wooden flakes 1, 1, . Similarly, the wood microflakes 2, 2, . . . are smaller and more uniform in size than the wood microflakes 1, 1, . uniformly formed. Therefore, even if the small wooden flakes 1, 1, . . . of the mat B1 and the microscopic wooden flakes 2, 2, . . . The generated steam smoothly escapes from the mats B1 and C1. That is, as shown on the left side of FIG. 11, a large number of minute voids exist between the mutually adjacent wooden flakes 1, 1, . . . in the mat B1. Similarly, in the mat C1 as well, there are many fine voids between the woody microflakes 2, 2, . . . adjacent to each other. These voids communicate not only in the fiber direction and the fiber orthogonal direction of the small wooden flakes 1, 1, ... and the very small wooden flakes 2, 2, ..., but also in the thickness direction. Moreover, these voids are continuous not only within the mats B1 and C1, but also between the mats B1 and C1, and are continuous three-dimensionally throughout the laminated mat A1. Therefore, punctures are less likely to occur when the pressure applied to the wooden laminate board Am is stopped.

Through such steps, each density of the first wooden material layer B and each of the second wooden material layers C (the density of the entire wooden laminated board Am) is 500 kg/m ³ or more and 800 kg/m ³ or less, and the bending Young is A laminated wood board Am having a pressure of 3.5 GPa or more and 5.0 GPa or less is formed.

The density of the first wooden material layer B and the density of each of the second wooden material layers C may be the same or different. It is preferable that the wood material layers B and C have different densities from the viewpoint of preventing puncture during molding. When the densities of the first wooden material layer B and each of the second wooden material layers C are different, the density difference between the two layers B and C is, for example, 400 kg/m ³ or more. Also, the magnitude relationship between the densities of the first wooden material layer B and each of the second wooden material layers C is not particularly limited. Good or low. From the viewpoint of improving smoothness and color tone/color uniformity in the surface properties of the wood laminate board Am, each second wood material layer C should be a high-density wood material layer having a density higher than that of the first wood material layer B. preferable.

In addition, as shown on the right side of FIG. 11, the wood laminate board Am has a large number of microscopic voids that are three-dimensionally continuous inside the first wood material layer B and each of the second wood material layers C ( Remaining). Therefore, the wood laminate board Am is also excellent in air permeability.

(Other processes)
In the method of manufacturing the laminated wood board Am, as other steps, after the heat pressing step P5, the laminated wood board Am is cured to the equilibrium moisture content, and then the second wooden material layers C as the front and back surfaces are ground with a sander, It may have a finishing step to adjust the final thickness. A commonly used sander can be used, for example, #150 sander. Through this finishing process, a wood laminate board Am having even better surface properties can be obtained.

Therefore, the wood laminate board Am of the present embodiment can have the following effects.

The wood laminate board Am is composed of two kinds of small wood flakes 1 and micro wood flakes 2 of the same thickness range but different sizes. Specifically, the wood laminate board Am has an extremely thin thickness t, the average value of which is 0.05 mm or more and 0.35 mm or less, and is defined by the average first length d1/average second length d2. A first wooden material layer B in which a large number of small wooden flakes 1, 1, . Two second wooden material layers C, C, which are composed of a single layer formed by bonding and integrating a large number of small wooden flakes 2, 2, . . . , and the second wooden material layers C, C are arranged on both sides of the first wooden material layer B, and are composed of three layers by adhesion and integration.

That is, the first wooden material layer B constituting the core layer of the wooden laminated board Am is constructed in the same manner as the wooden board As. Therefore, not only is the strength of the first wood material layer B (that is, the wood laminate board Am) increased, warping due to moisture absorption and desorption is less likely to occur, and good dimensional stability comparable to that of plywood made of South Sea wood can be obtained. In addition, the two second wooden material layers C, C constituting the front and back layers of the wooden laminate board Am have an area (specifically, the first length d1 and the second length At least one dimension of the width (width) d2) is small, and the large number of small wooden flakes 2, 2, . . . Thus, the wood laminate board Am has even better surface properties, and has excellent surface properties similar to MDF. Also, the mat B1 and the mat C1, which are aggregates in which a large number of small wood flakes 1, 1, . . . and micro wood flakes 2, 2, . Since the layers are laminated and integrated in the order of , the manufacturing thereof is also facilitated.

In particular, the average value of the thickness t of the small wooden flakes 1, 1, ... in the first wooden material layer B constituting the core layer of the wooden laminated board Am is 0.15 mm or more and 0.25 mm or less, and the aspect ratio (d1 When /d2) is 4 to 40, the dimensional stability of the first wood material layer B is improved, and as a result, the dimensional stability of the wood laminate board Am is improved. In addition, since the smoothness of the surface of the first wooden material layer B is improved, the surfaces of the second wooden material layers C, C laminated on the first wooden material layer B also have smoothness and color tone/color uniformity. improves. As a result, a wood laminate board Am having even better surface properties can be obtained.

In addition, the average value of the thickness of the wooden microflakes 2, 2, ... in each of the second wooden material layers C constituting the front and back layers of the wooden laminated board Am is 0.15 mm or more and 0.25 mm or less, and the aspect ratio (d1 When /d2) is 5 to 10, the surface property of each second wood material layer C, that is, the wood laminate board Am is further improved.

Moreover, when the ratio of the thickness of each second wooden material layer C to the whole laminated wood board Am is 5% or more and 40% or less, both the strength and surface properties of the laminated wood board Am can be achieved.

FIG. 12 exemplifies the characteristics of the wood laminate board Am according to the present invention in comparison with boards made of other materials. It is as large as plywood, and is superior to lauan plywood in terms of anisotropy in dimensional stability, smoothness in surface properties, and color tone/color uniformity. In addition, compared with OSB, the wood laminate board Am has uniform bending Young in the vertical and horizontal directions, and is excellent in anisotropy in dimensional stability, smoothness in surface properties, and color tone/color uniformity. That is, the wood laminate board Am has high strength and excellent dimensional stability and surface properties. In addition, the wood laminate board Am has not only the above characteristics, but also the single-layer wood board (in other words, the first wood material layer B) composed only of the small wood flakes 1, 1, . . . In addition, it can be said that it is a wooden board that specializes in surface properties.

<Other embodiments>
In the above embodiment, the wood board As (in the second embodiment, the first wood material layer (core layer) B) is obtained by crushing wood flakes cut from raw wood (wood flakes after cutting). However, the present invention can also be composed of wood flakes cut from raw wood (wood flakes after cutting).

In the above-described embodiment, both the wooden flake manufacturing process P1 and the small wooden flake manufacturing process P2 have a classifying step, but in the present invention, only one of the steps P1 and P2 includes a classifying step. None of the steps P1 and P2 may include the classification step. From the viewpoint of further improving not only the strength of the wooden board As but also the dimensional stability and surface properties, the step P1 or P2 preferably includes a classification step, and the step P2 includes a classification step. is more preferred, and it is even more preferred that both steps P1 and P2 have a classification step.

INDUSTRIAL APPLICABILITY The present invention is extremely useful because it can easily produce a wooden board composed of small wooden flakes of a uniform size and having high strength and good dimensional stability and surface properties comparable to those of plywood made from South Sea wood. and has high industrial applicability.

As wood board Am wood laminate board (wood board)
A1 Mat B First wooden material layer B1 Mat C Second wooden material layer C1 Mat P1 Wood flake manufacturing process P2 Small wood flake manufacturing process P3 Adhesive application process P4 Mat forming process P5 Heat pressing process P6 Wood micro flake manufacturing process 1 Wood Small flake 1a Fiber 2 Wood microflake 2a Fiber t Thickness d1 First length d2 Second length

Claims (7)

A wooden board in which a large number of small wooden flakes having front and back surfaces along the fiber direction are laminated together and bonded together,
The wooden flake has a thickness between the front and back surfaces of 0.05 mm or more and 0.35 mm or less, and has a first length along the fiber direction/a second length along the fiber orthogonal direction orthogonal to the fiber direction. A wooden board characterized by having an aspect ratio defined by length of 4 to 80. In the wooden board according to claim 1,
A wooden board, wherein the wooden flakes have a thickness of 0.15 mm or more and 0.25 mm or less and an elongated shape with an aspect ratio of 4 to 40. In the wooden board according to claim 1,
The area of the front and back surfaces of the wooden flakes is 6 cm. ² A wooden board characterized by: In the wooden board according to claim 1,
Wooden material layers are laminated and integrated on the front and back surfaces of the wooden board,
A wooden board, wherein said wooden material layer is formed by stacking and bonding together microscopic wooden flakes having an area smaller than that of said small wooden flakes. In the wooden board according to claim 4 ,
A wooden board, wherein the ratio of the thickness of the wooden material layer to the entire wooden board is 5% or more and 40% or less. In the wooden board according to any one of claims 1 to 5 ,
A wood board having a density of 500 kg/m ³ or more and 800 kg/m ³ or less. In the wooden board according to any one of claims 1 to 5 ,
A wood board characterized by having a surface root mean square height Sq of 0.005 μm or more and 0.015 μm or less, or a surface arithmetic mean height Sa of 0.002 μm or more and 0.007 μm or less.

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