JP2023164247A - Wooden board - Google Patents

Abstract

To provide a wooden board As that has high strength, is superior in dimensional stability and surface nature, and can be produced easily and simply.SOLUTION: A wooden board As is obtained by laminating, bonding, and integrating, in an aggregated state, a large number of small thin wood pieces 1 with top and bottom surfaces extending along the fibers. In the small thin wood pieces 1, the top and bottom surfaces have an area of 6 cm2 or less, and a thickness (t) ranges from 0.05 mm to 0.35 mm, or an aspect ratio (d1/d2) ranges from 4 to 80 as defined by (a first length d1 along the fibers)/(a second length d2 in a direction orthogonal to the fibers).SELECTED DRAWING: Figure 1

Description

The present invention relates to a wooden board.

In general, South Sea plywood such as lauan plywood is well known and widely used as an existing wood board. However, in recent years, it has become difficult to obtain South Sea plywood due to the depletion of raw materials and the prevention of environmental damage, and efforts are being made to replace it with other wood boards.

Plywood made from domestically produced coniferous trees has no problem in terms of raw material depletion, but due to its lack of surface properties, it is limited to applications focused on strength.

There is no problem with OSB, PB (particle board), and MDF as raw materials. However, although OSB has high strength, there is a problem in that its surface properties are insufficient. PB is cheap, but has the problem of lacking strength. Although MDF has good surface properties, it does not have sufficient dimensional stability. Furthermore, OSB, PB, and MDF have a disadvantage in that they have a higher density than South Sea plywood.

As described above, currently there is no wood board that satisfies multiple 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, those shown in Patent Documents 1 to 4 have been proposed. The wooden boards shown in Patent Document 1 and Patent Document 2 include a core layer made of a large number of wood flakes, and a surface layer laminated on at least one side of the core layer and made of a large number of wood flakes. It is. In the wooden 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. It is proposed that.

On the other hand, in the technology shown in Patent Document 3, a fiber mat is pressure-bonded to the surface of plywood, OSB, laminated wood, etc., and this fiber mat is compressed to create a high-density fiber layer. I'm trying to fill in the dents on the surface.

In addition, the floor decorative material shown in Patent Document 4 has a structure in which a moisture-proof film with a moisture permeability of 7 g/m ^2.24 hours or less is laminated on the back side of a wood base material such as MDF, so that the front side has a moisture-permeable layer. Even if a low decorative sheet is applied, warping and bending due to the magnitude of dimensional changes are suppressed.

Japanese Patent Application Publication No. 7-47514 Japanese Patent Application Publication No. 7-76004 JP 2019-31104 Publication JP 2019-107894 Publication

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

In addition, the wood 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 difficult to reduce the thickness of the board. There are limits. Further, dimensional changes due to moisture absorption cannot be suppressed.

Furthermore, in the decorative material of Patent Document 4, 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 the above points, and its purpose is to provide high strength, excellent dimensional stability and surface quality, and to improve manufacturing efficiency by applying improved technology to a wooden board with a structure in which a large number of wood flakes are laminated. The object of the present invention is to make it possible to easily obtain a wooden board (base material).

In order to achieve the above object, this invention uses wood flakes whose size including thickness is limited to a microscopic range, compared to cut pieces that are normally used as constituent materials of OSB. Small wood flakes whose size is further limited to a very small range are used as the constituent material, and a large number of these small wood flakes are laminated together in an aggregated state to form a wood board.

In addition, in this invention, a core layer and a front and back layer are laminated and integrated on the front and back surfaces of the wooden board, the wood layer is made of very small wood flakes whose size is further limited to a microscopic range. Made of wood laminated board.

In this specification, the term "cutting piece" refers to a piece cut from logs for OSB use, and a piece commonly used as a constituent material of OSB. The "wooden flakes" according to the present invention are those cut from logs in the same way as "cuttings", but are thinner and smaller flakes that are outside the normal thickness range of "cuttings". . A "small wood flake" according to the present invention refers to a thin flake smaller than the "wood flake" within the same thickness range as the "wood flake".

Specifically, the first invention is directed to a wooden board formed by laminating a large number of small wooden pieces having front and back surfaces along the fiber direction in a collective state and bonding them together. The small wooden pieces constituting this wooden board are characterized in that the area of the front and back surfaces is 6 cm ² or less, and the thickness between the front and back surfaces is 0.05 mm or more and 0.35 mm or less.

Similar to the first invention, the second invention is directed to a wooden board formed by laminating a large number of small wooden pieces having front and back surfaces along the fiber direction in a collective state and bonding them together. The small wooden flakes constituting this wooden board have an area of 6 cm ² or less on the front and back surfaces, and have a first length along the fiber direction/a second length along the fiber direction perpendicular to the fiber direction. It is characterized by an aspect ratio defined by 4 to 80.

In the first or second invention, the wooden board has a large number of small wooden flakes having an area of 6 cm ² or less and a thickness of 0.05 mm or more and 0.35 mm or less, or an aspect ratio of 4 to 80. It is constructed by laminating them together and bonding them together. The thickness, first length, and second length of the small wood flakes are all average values.

Specifically, the wood board is obtained by pulverizing wood flakes having a specific thickness obtained in the P1 step described below in a first direction of the wood flakes and in a second direction orthogonal to the first direction in the P2 step also described below. It is composed of small wood flakes of only one type of size, and the area of the front and back surfaces of the small wood flakes is within a narrow range of 6 cm ² or less, so the variation in area of the large number of small wood flakes is small. It becomes uniform in area (size). In addition, the thickness of small wood flakes is extremely thin and falls within a certain range, or the aspect ratio defined by average first length/average second length is also within a certain range, so wood boards have a constant shape. Small wood flakes arranged within a certain range gather together to form a homogeneous product. Therefore, not only does the strength of the wooden board become higher, but it also becomes less prone to warping due to moisture absorption and release, and can achieve good dimensional stability comparable to that of South Sea plywood. Furthermore, since the large number of small wood flakes are uniform in thickness and shape, the surface of the wood board does not have large irregularities unlike normal OSB, and the wood board has excellent surface properties. Furthermore, since a large number of small wooden pieces of uniform size are assembled and laminated, manufacturing thereof is also facilitated.

A third or fourth invention is directed to a wood board according to the first or second invention, in which wood layers are laminated and integrated on the front and back surfaces of the wood board. The wood layers constituting the front and back layers of this wood laminated board are characterized in that very small wood flakes having an area smaller than the above-mentioned small wood flakes are laminated in a cluster and bonded together. Note that the area refers to a value obtained by multiplying the first length and the second length, and refers to the area of the front and back surfaces along the fiber direction.

In the third or fourth aspect of the present invention, the wooden laminated board includes a wooden board constituting the core layer and a wooden material layer constituting the front and back layers, which are laminated together. The wood material layer is constructed by laminating a large number of very small wood flakes whose area is smaller than that of the small wood flakes in an aggregated state and bonding them together.

In this way, wood laminated boards are made by grinding wood flakes with a specific thickness obtained in the P1 process described below in two different sizes in the first and second directions of the wood flakes in the P2 process and P6 process, which will also be described later. It is composed of small woody flakes. Since the wood laminated board includes a wood board made of small wood flakes in the core layer, the same effect as the wood board of the first invention is achieved. Furthermore, the wood laminated board is made up of a large number of very small wood flakes with an area smaller than the small wood flakes, and the wood layer is laminated on both sides of the wood board to form the front and back layers. No large irregularities occur on the surface, and the surface properties can be further improved, and the material has excellent surface properties similar to MDF. In addition, the wood laminated board is an aggregate made up of many small wood flakes of uniform size, an aggregate made of a large number of small wood flakes of uniform size, and an aggregate made of very small wood flakes of uniform size. Since they are sequentially laminated and integrated, manufacturing is also facilitated.

A fifth invention is a wood board (wood laminated board) according to the third or fourth invention, wherein each wood layer has a thickness ratio of 5% to 40% of the entire wood board (wood laminated board). characterized by something. This makes it possible to achieve both strength and surface properties of the wood laminated board.

A sixth invention is characterized in that the wood board according to any one of the first to fourth 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 provides the wooden board according to any one of the first to fourth inventions, wherein the root mean square height Sq on the surface is 0.005 μm or more and 0.015 μm or less, or the arithmetic mean height Sa on the surface is 0.005 μm or more and 0.015 μm or less. 0.002 μm or more and 0.007 μm or less. This further improves the surface properties of the wooden board. In this specification, the surface quality of a wooden board refers to the surface quality of a wooden board that has been adjusted to a product thickness using, for example, a #150 sander.

As explained above, according to the present invention, a wooden board is formed by laminating a large number of small wood flakes having front and back surfaces along the fiber direction and bonding them together, and the surface of the small wood flakes is By setting the area of the back side to be 6 cm2 ^or less and the thickness to be 0.05 mm or more and 0.35 mm or less, or the aspect ratio defined by the first length/second length to be 4 to 80, a large number of small wood flakes can be It has a uniform size with little variation, making it possible to increase the strength of the wooden board, and it also has good dimensional stability and surface properties comparable to South Sea plywood, making it easy to make the wooden board. can be manufactured.

FIG. 1 is a sectional view of a wooden board according to a first embodiment of the present invention. FIG. 2 is an enlarged sectional view of the waist portion of the wooden board according to the first embodiment. FIG. 3 is an enlarged perspective view schematically showing small wooden pieces 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 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 pieces. 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 sectional view of a wooden board according to a second embodiment of the present invention. FIG. 8 is an enlarged sectional view of a main part of a wooden board according to a second embodiment. FIG. 9 is an enlarged perspective view schematically showing a very small wooden piece constituting the wooden material layer according to the second embodiment. FIG. 10 is a diagram showing a manufacturing process of a wooden board according to the second embodiment. FIG. 11 is an enlarged sectional view showing a state in which a wooden board according to the second embodiment is hot-pressed from a mat that is an aggregate of small wooden flakes and 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.

Hereinafter, embodiments of the present invention will be described in detail based on the drawings. The following description of the embodiments is merely illustrative in nature and is in no way intended to limit the present invention, its applications, or its uses.

[First embodiment]
<Wood board>
FIG. 1 shows a wooden board As according to a first embodiment of the present invention. This 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, for example. Thin wood boards As with a thickness of 3 mm or more and less than 6 mm are used, for example, as inner wall materials for loading beds of vehicles such as trucks, base materials for cushion floors constructed indoors, decorative surface materials, and interior building materials (riseers). It is constructed as an interior material such as panels (boards, etc.). The medium-thick wood 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 installed indoors, a floor base material for shoes, a doorway construction material, etc. In this way, the wood board As is used as a substitute for the existing plywood for the base plate. This wooden board As will be explained in detail.

As shown in an enlarged view in FIG. 2, the wooden board As is made up of a large number of small wooden pieces 1, 1,... having front and back surfaces along the fiber direction, which are laminated together and bonded together. The small wood flakes 1, 1, . . . have one type of thickness.

To explain the small wood flakes 1, as shown in an enlarged view in FIG. 3, the thickness t of the small wood flakes 1 is from 0.05 mm to 0.35 mm, preferably from 0.10 mm to 0.30 mm, Preferably it is 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 thin pieces 1, 1, . . . having a thin thickness t. The thickness t of the small wood flakes 1 is an average value. In other words, the small wood flake 1 is a strand (also referred to as a cut piece in the present invention) that is normally used as an element (constituent material) of a general OSB, and generally has a thickness of about 0.6 mm to 1.5 mm. However, it is a thinner flake than that.

In addition, the small wood flakes 1 have an average value 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 to 80. That is, the small wooden piece 1 may be square or elongated (rectangular). When the small wood flake 1 has an elongated shape, the first length d1 is the longitudinal dimension (length), and has fibers 1a, 1a, . is the fiber direction dimension. Further, the second length d2 is a dimension (width) in the lateral direction, and is, for example, a dimension in the direction perpendicular to the fibers along a direction orthogonal to the fiber direction. The aspect ratio is preferably 2 to 70, more preferably 3 to 55, even more preferably 4 to 40. As will be described later, the small wood flakes 1, although not shown, are wood flakes that have been cut from raw wood (also referred to as post-cut wood flakes) and have been crushed into smaller pieces. To define something different from a wood flake, the wood flake after cutting is referred to as a "small wood flake."

The area of the front and back surfaces of the small wooden piece 1 (the 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. Further, the lower limit of the area is, for example, 0.5 cm ² or more.

The tree species used for the small wood flakes 1, 1, . . . are not particularly limited, and, for example, South African trees and broad-leaved trees may be used, or other tree species may be used. For example, there are firs such as cedar, cypress, and Douglas fir, acacia, aspen, poplar, pine (hard pine, soft pine, radiata pine, etc.), birch, and rubber (rubber tree), but it is limited to these tree species. Furthermore, various tree species can be used. Various tree species include Sakhalin pine, Japanese larch, Ezo pine, Spanish mackerel, Japanese cypress, Japanese cypress, Japanese cypress, toga, Japanese pine, various pines, paulownia, maple, birch (white birch), shii, beech, Japanese oak, Japanese fir, Japanese oak, oak, camphor tree, and zelkova. Domestic materials such as rice cypress, rice cypress, rice cedar, rice fir, spruce, rice toga, redwood, etc., North American materials such as agathis, terminaria, lauan, meranti, juncon, chamelele, kalampayan, amberoi, melina, teak, apitong Any material can be used, including South Sea woods such as , Sengon Laut, balsa, cedro, mahogany, lignum vitae, acacia mangium, Mediterranean pine, bamboo, kolyang, and other foreign woods such as chameleon.

Regarding the physical properties of the small wood flakes 1, the density thereof 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. If the density is less than 250 kg/ ^m3 , the thickness of the mat required to form the wood board As of the same density and strength will increase, and the press pressure related to the hot press treatment in the press forming process will be increased. It is necessary to increase it.

Although the density of the small wood flakes 1 may exceed 800 kg/m ³ , it is difficult to easily obtain such small wood flakes 1. 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 small wood flakes 1 exceeding 800 kg/m ³ can be easily obtained.

Further, the moisture content of the small wood flakes 1 is preferably about 2 to 20%, more preferably 2 to 8%. When the water content is less than 2%, it takes time for softening in the hot press treatment in the press molding process, resulting in a long press time and a risk of a decrease in strength.

In addition, if the moisture content of the small wood flakes 1 exceeds 20%, it will take time to heat and compress during the hot press process, and furthermore, there is a risk that the curing of the adhesive will be inhibited and the strength will decrease. .

In the wood board As, the fiber direction (length direction) of the large number of small wood flakes 1, 1, ..., which is the direction along the fibers 1a, 1a, ..., may be oriented in the reference direction, This fiber orientation is not essential, and the fiber directions may be randomly oriented. Furthermore, the fact that the fiber direction (length direction) is oriented in the reference direction means that the fibers 1a, 1a, . . . of all the small wood flakes 1, 1, . In other words, the fiber directions of the oriented small wood flakes 1, 1, . . . are not limited to being parallel to each other. Some of the small wood flakes 1, 1,... may include small wood flakes 1, 1,... whose fiber direction is inclined to some extent (for example, about 20 degrees) with respect to the reference direction.

<Manufacturing method of wood board>
Next, a method for manufacturing the small wood flakes 1 and a method for manufacturing the wood board As from the small wood flakes 1 will be explained with reference to FIG. 4. The method for producing the small wood flakes 1 includes a wood flake manufacturing process P1 and a small wood flake manufacturing process P2. The method for manufacturing the wooden board As further includes subsequent adhesive application step P3, mat forming step P4, and hot pressing step P5.

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

At this time, each wooden flake is cut so that the fibers appear in a straight line on the front and back surfaces, and the cut thickness is the thickness t of the small wooden flake 1. In the subsequent steps, basically the thickness t of the small wood flake 1 does not change from the thickness of the wood flake after cutting, and the thickness of the wood flake after cutting becomes the thickness t of the small wood flake 1. be.

The cut wood flakes obtained in this step P1 are passed through a sieve (for example, a mesh with a diameter of 5 mm or more), and the size of the cut wood flakes is sorted (classified) (classification step). In some cases, wood flakes of a size comparable to the small wood flakes 1, 1, ... obtained after passing through the flake manufacturing process P2 (included in the size range of the first small wood flakes 1, 1, ...) are obtained. be. In that case, the wood flakes can be used as the small wood flakes 1, 1, . . . in the adhesive application process P3 without being subjected to the small wood flake manufacturing process P2.

(Small wood flake manufacturing process P2)
Next, after the above-mentioned cutting, the wood flakes classified as necessary (wood flakes after cutting) are crushed using a crusher that does not use a blade such as a hammer mill, pin mill, or jet mill, or a blade that does not use a blade such as a knife flaker or a cutter mill. The wood flakes are crushed using a machine and made smaller than the size of the wood flakes immediately after cutting in the direction orthogonal to the fibers, thereby forming small wood flakes 1, 1, . . . that constitute the wood board As. At this time, by crushing the wood flakes in the width direction so as to split them along the fiber direction (lengthwise direction) after cutting, small elongated wood flakes 1, 1, . . . can be produced. In other words, if a force (impact) is applied to a wood flake after cutting along a direction perpendicular to the fiber direction, it will not easily break, but if a force is applied parallel to the fiber direction, it will easily break. Even if the wood flakes are curled after cutting, they are divided into flat pieces by crushing. Note that the direction of the force applied to the wood flakes after cutting is not limited to the direction parallel to the fiber direction. When a force is applied in a random direction to a wood flake after cutting, the wood flake after cutting usually breaks from the part where the force is weaker (it tends to break in the direction of weaker force). The force that connects each fiber of a wood flake after cutting (force in the direction perpendicular to the fibers) is overwhelmingly weaker than the force in the fiber direction, so if you crush the wood flake in a random direction after cutting using the general crusher mentioned above, (When force is applied), the wood flakes after cutting are broken along the fiber direction and shortened in the direction perpendicular to the fibers, yielding small elongated wood flakes 1, 1, . . . .

Furthermore, even if there are wood knots in the wood flakes after cutting, the knots are more brittle than other parts, so the knots are turned into powder by pulverization and removed in a subsequent classification step.

In addition, in the case of a crusher that uses blades, there is a risk that the wood flakes may be unintentionally crushed in the direction perpendicular to the fibers after cutting, but in the case of a crusher that does not use blades, this risk is reduced. It is preferable to crush the wood flakes after cutting using a crusher that does not use a blade.

In this way, instead of just the one-step cutting process, by adding a crushing process and going through a two-step process, the cut wood flakes, which are thinner and smaller than the cut pieces, can be cut into knots of the required size. It is possible to easily produce high-strength small wood flakes 1, 1, . . . without parts.

A classification step may be included in which the small wood flakes 1, 1, ... obtained in the above-mentioned crushing step are passed through a sieve or the like, and the sizes of the small wood flakes 1, 1, ... are sorted (classified). As a result, the large number of small wood flakes 1, 1, . . . become fine and more uniform in size and shape. The small wood flakes 1 are manufactured by the above steps.

(Adhesive application process P3)
In the small wood flake manufacturing process P2, when a large number of small wood flakes 1, 1, ... which are fine and uniform in size and shape are obtained by sorting, an adhesive application process P3 is performed, and the small wood flakes 1 are , 1, ... are carried into an adhesive coating device and adhesive is applied thereto. 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 also be used. . Further, a commonly used water repellent may be used together with the adhesive.

(Matt forming process P4)
Next, as shown on the left side of FIG. 5, a large number of small wood flakes 1, 1, ... coated with the adhesive are assembled in the thickness direction, with or without orientation in the fiber direction. A mat A1 of the small wood flakes 1, 1, . . . is formed by laminating (stacking) them to a predetermined thickness (height). For example, when forming a wooden board As with a thickness of 4 mm, small wooden pieces 1, 1 with a thickness t of 0.2 mm, Accumulate...

(Heat pressure process P5)
This mat A1 is carried into a hot press machine and set between hot plates, and the hot press machine heats the mat A1 at a predetermined pressure and temperature to compress it, and then hardens the adhesive to make it into one piece. Shape. In this way, the wooden board As shown in FIG. 1 is formed.

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

In addition, the knots of the small wood flakes 1, 1, ... have been removed, and the sizes are kept within a small range without variation, so they are homogeneous throughout the mat A1, and as a result, There is no variation in the strength of the wooden board As. In other words, in a strand board that uses large strands (cut pieces), for example, uneven mats including knots may produce thin, low-strength areas in spots, resulting in variations in strength, but this is eliminated. Moreover, the thinner the small wooden pieces 1, 1, . . . , the higher the homogeneity of the mat A1 becomes, and the stronger the wooden board As becomes. In general, strand board using large strands (cuttings) can increase the strength, but in the present invention, the wood flakes 1 are thinner and smaller than the cuttings (wooden flakes after cutting) and are made smaller by crushing. It serves both the homogeneity and strength of the board As.

Furthermore, the small wood flakes 1, 1,... are small and uniform in size, and gaps are uniformly formed between the small wood flakes 1, 1,... in the mat A1. Even if the small wood flakes 1, 1, . . . are hot-pressed while still containing a relatively large amount of moisture, the 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, in the mat A1, there are many minute voids between the mutually adjacent small wooden pieces 1, 1, . . . . These voids communicate not only in the fiber direction and perpendicular direction to the fibers of the small wood flakes 1, 1, . . . but also in the thickness direction, and are three-dimensionally continuous. Therefore, punctures are less likely to occur when the pressure on the wooden board As is stopped.

Through these steps, a wood board As having a density of 500 kg/m ³ or more and 800 kg/m ³ or less and a bending Young of 3.5 GPa or more and 7.0 GPa or less is formed. As shown on the right side of FIG. 5, this wooden board As has (remains) many three-dimensionally continuous minute voids inside thereof. Therefore, the wooden board As also has excellent breathability.

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

<Surface properties of wood board>
The wooden board As preferably has a root mean square height Sq of 0.005 μm or more and 0.015 μm or less on the surface, or an arithmetic mean height Sa of 0.002 μm or more and 0.007 μm or less on the surface. Note that the surface of the wooden board As refers to the surface of the wooden board As after the above-mentioned finishing step, for example, the surface of the wooden board As that has been 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 surface properties defined by ISO25178. That is, the wooden board As has excellent surface properties by controlling the parameters Sq and Sa that specify the surface properties within specific ranges.

The root mean square height Sq is a parameter that corresponds to the standard deviation of the distance from the average plane, and corresponds to the standard deviation of the 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 surface irregularities, and the better the surface properties. Specifically, if the thickness t of the small wooden flakes 1, 1, ... is 0.35 mm or less, the root mean square height Sq on the surface of the wooden board As will be about 0.005 μm or more and 0.015 μm or less, If the thickness t of the small wooden pieces 1, 1, ... is 0.25 mm or less (preferably 0.20 mm or less), the root mean square height Sq on the surface of the wooden board As is 0.005 μm or more and 0.008 μm or less Since the surface roughness is comparable to that of MDF, which has excellent surface properties, wooden board As has even better surface properties and is therefore preferable.

The arithmetic mean height Sa represents the average of the absolute values of the differences in height of each point with respect to the average 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 irregularities the surface has, and the better the surface properties. Specifically, if the thickness t of the small wooden flakes 1, 1, ... is 0.35 mm or less, the arithmetic mean height Sa on the surface of the wooden board As is about 0.002 μm or more and 0.007 μm or less, and the wood If the thickness t of the small flakes 1, 1, ... is 0.25 mm or less (preferably 0.20 mm or less), the arithmetic mean height Sa on the surface of the wooden board As will be about 0.002 μm or more and 0.005 μm or less. Since the surface roughness is comparable to that of MDF, which has excellent surface properties, wooden board As has even better surface properties and is therefore preferable.

Note that the surface quality of the wooden board As is not limited to the root mean square height Sq and the arithmetic mean height Sa, but for example, the skewness Ssk, the maximum valley depth Sv, the maximum peak height Sp, and the maximum valley depth Sv. It may be specified by the maximum height Sz indicating the sum, the kurtosis Sku, etc.

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

The wooden 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. The ratio of the second length d2 along the direction perpendicular to the fibers to the average value: 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 wood flakes 1, 1, . . . are laminated together in a single layer by adhesion and integration.

That is, the single-layer wooden board As is composed of only one type of small wood flakes 1, 1,..., and the thickness t of the small wood flakes 1, 1,... is extremely thin, ranging from 0.05 mm to 0.35 mm. Since the thickness falls within a narrow range of the following, the large number of small wood flakes 1, 1, . . . have a uniform thickness t with small variations in thickness t. In addition, since the aspect ratio (d1/d2) of the small wood flakes 1, 1, ... is within a certain range, the wood board As is made up of small wood flakes 1, 1, ... whose sizes are within a certain range. It becomes homogeneous. Therefore, not only the strength of the wooden board As is increased, but also warping due to moisture absorption and release is difficult to occur, and good dimensional stability comparable to that of South Sea wood plywood can be obtained. In addition, since the large number of small wooden flakes 1, 1, ... are uniform in size, there is no large unevenness on the surface of the wooden board unlike with normal OSB, and the wooden board As has excellent surface properties. It becomes something. Further, since a large number of uniformly shaped wood thin pieces 1, 1, .

In particular, if the average value of the thickness t of the small wooden flakes 1, 1, ... in the wooden board As is 0.15 mm or more and 0.25 mm or less, and the aspect ratio (d1/d2) is an elongated shape with an aspect ratio (d1/d2) of 4 to 40, , the dimensional stability and surface properties of the wooden board As are further improved.

FIG. 6 illustrates 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 has superior anisotropy in dimensional stability and color tone and color homogeneity in surface properties compared to lauan plywood. Furthermore, compared to OSB, wooden board As has uniform bending young in the vertical and horizontal directions, and has good anisotropy in dimensional stability, smoothness in surface properties, and color tone/color homogeneity. That is, the wooden board As has high strength and excellent dimensional stability and surface properties.

[Second embodiment]
<Wood board (wood laminated 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 also be called a wooden laminated board. Hereinafter, the wooden board Am will also be referred to as the wooden laminated board Am. Note that the configuration of the wooden board As other than the wooden layer constituting the wooden laminated board Am is the same as that of the first embodiment, so a detailed explanation will be omitted here. In addition, the same reference numerals are given to the same components as in the first embodiment, and the explanation thereof will be omitted.

The wood laminated 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. Thin type wood laminated 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 loading beds of vehicles such as trucks, as a base material for cushion floors installed indoors, as a decorative surface material, as an interior building material ( It is constructed as an interior material such as risers etc.). The medium-thick wood laminate board Am having a thickness of about 6 mm or more and 12 mm or less is used, for example, as a soundproof floor base material constructed indoors, a floor base material for shoes on, a doorway construction material, etc. In this way, the wood laminated board Am is used as an alternative material to the existing plywood for the base plate. Moreover, since the wood laminated board Am has surface properties similar to MDF, it can be suitably used as a decorative thin plywood.

The wood laminated board Am includes a first wood layer B and two wood layers (hereinafter also referred to as "second wood layers") C and C, and a second wood layer is formed on both sides of the first wood layer B. Material layers C and C are laminated and integrated. In other words, the first wood material layer B is interposed between the two second wood material layers C, C. That is, the first wood material layer B constitutes the core layer of the wood laminate board Am, and the two second wood material layers C and C constitute the front and back layers of the wood laminate board Am.

The ratio of the thickness of each second wood layer C to the entire wood laminate board Am is preferably 5% or more and 40% or less, more preferably 8% or more and 30% or less, and even more preferably 10% or more and 25% or less. be. That is, the ratio of the second wood layer C: the first wood layer B: the second wood layer C in the wood laminated board Am is preferably 5:90:5 to 40:20:40, more preferably 8:84: The ratio is 8 to 30:40:30, more preferably 10:80:10 to 25:50:25. By appropriately changing the ratio of the thickness of the first wood material layer B and each of the second wood material layers C, a wood laminated board Am that has both the necessary strength and excellent surface properties depending on the application can be obtained. .

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

(Second wood layer)
As shown in an enlarged view in FIG. 8, the second wood material layer C is made up of a large number of very small wood flakes 2, 2, ... having front and back surfaces along the fiber direction, which are laminated in an aggregate state and bonded together. , a large number of tiny wood flakes 2, 2, . . . have one type of thickness.

The very small wooden piece 2 is a thin piece that is smaller in size (the area of its front and back surfaces) than the small wooden piece 1. To explain in detail about the very small wooden flakes 2, as shown in an enlarged view in FIG. .30 mm or less, even more preferably 0.15 mm or more and 0.25 mm or less, still more preferably 0.15 mm or more and 0.20 mm or less. That is, the thickness t of the very small wooden piece 2 is equal to or smaller than the thickness t of the small wooden piece 1. As a result, the characteristics of the second wood layer C, that is, the characteristics of the wood laminated board Am, are determined by the very small wooden pieces 2, 2, . . . having a thin thickness t. The thickness t of the very small wooden slice 2 is an average value.

Further, the aspect ratio (d1/d2) of the very small wood flakes 2, which is defined similarly to the small wood flakes 1, is preferably 1 to 500. That is, the very small wooden piece 2 may have a square shape or an elongated shape (rectangular shape). When the very small wooden flake 2 has an elongated shape, the first length d1 is the longitudinal dimension (length), similar to the small wooden flake 1, and it has fibers 2a, 2a, . , is the fiber direction dimension in the direction along the fiber 2a. Further, the second length d2 is a dimension (width) in the lateral direction, and is, for example, a dimension in the direction perpendicular to the fibers along a direction orthogonal to the fiber direction. The aspect ratio is preferably 2 to 100, more preferably 3 to 12.5, even more preferably 5 to 10.

Note that the area of the front and back surfaces of the very small wooden flake 2 is not particularly limited as long as it is smaller than the area of the front and back surfaces of the small wooden flake 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 tree species used for the very small wood flakes 2, 2,... are not particularly limited, and the same tree species as the wood species used for the small wood flakes 1, 1,... may be used, or other tree species may be used. . Further, the tree species of the very small wood flakes 2, 2, . . . may be the same as or different from the tree species of the small wood flakes 1, 1, . From the viewpoint of easily producing the tiny wood flakes 2, 2,... using the small wood flakes 1, 1,..., the wood species of the tiny wood flakes 2, 2,... are the same as the wood species of the small wood flakes 1, 1,... Preferably they are the same.

Regarding the physical properties of the tiny wood flakes 2, the density thereof 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. If the density is less than 250 kg/ ^m3 , the thickness of the mat required to form the wood laminated board Am of the same density and strength will increase, and the press pressure related to the hot press treatment in the press molding process will increase. It is necessary to increase

Although the density of the very small wood flakes 2 may exceed 800 kg/m ³ , it is difficult to easily obtain such very small wood flakes 2. 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 it is possible to easily obtain the very small wood flakes 2 with a weight exceeding 800 kg/m ³ .

Further, the moisture content of the very small wooden flakes 2 is preferably about 2 to 20%, more preferably 2 to 8%.

In the second wood material layer C, a large number of very small wood flakes 2, 2, ... are oriented in the reference direction even if the fiber direction (length direction), which is the direction along the fibers 2a, 2a, ..., is oriented in the reference direction. However, this orientation of the fiber direction is not essential, and the fiber direction may be randomly oriented. Some of the very small wood flakes 2, 2, . . . may include those whose fiber direction is inclined to some extent (for example, about 20°) with respect to the reference direction.

<Manufacturing method of wood board (wood laminated board)>
Next, a method for producing the small wood flakes 1, 1,... and very small wood flakes 2, 2,..., and a method for producing the wood laminated board Am from these small wood flakes 1, 2,... will be explained with reference to FIG. . The method for producing the small wood flakes 1, 1, . . . includes a wood flake manufacturing process P1 and a small wood flake manufacturing process P2. The method for producing the very small wooden flakes 2, 2, . . . further includes a subsequent very small wood flake manufacturing step P6. The method for manufacturing the wood laminated board Am further includes subsequent adhesive application step P3, mat forming step P4, and hot pressing step P5.

(Wood flake manufacturing process P1)
Since the wood flake manufacturing process P1 is the same process as the wood flake manufacturing process P1 according to the first embodiment, detailed explanation will be omitted here. In the subsequent steps, basically the thickness t of the small wood flakes 1 and the very small wood flakes 2 does not change from the thickness of the wood flakes after cutting, and the thickness of the wood flakes after cutting remains unchanged. The thickness of the very small wooden piece 2 is t.

(Small wood flake manufacturing process P2)
Since the small wood flake manufacturing process P2 is also the same process as the small wood flake manufacturing process P2 according to the first embodiment, detailed explanation will be omitted here.

(Wood microscopic flake manufacturing process P6)
In the small wood flakes manufacturing process P2, from the small wood flakes 1, 1,... formed and the small wood flakes 3, 3,... (not shown) removed in the classification process of the small wood flakes 1, 1,... It is possible to obtain very small wood flakes 2, 2, . . . which are smaller in size than the small wood lamellas 1, 1, . Note that the small wood flakes 3 removed in the above classification process refer to small wood flakes other than the small wood flakes 1 formed in the small wood flake manufacturing process P2, and the size of the small wood flakes 1 (thickness t and refers to small wood flakes with at least one aspect ratio outside the range.

Specifically, the small wood flakes 1, 1, . . . and/or the small wood flakes 3, 3, . . . are further crushed using the same method as the small wood flake manufacturing process P2. As a result, the small wood flakes 1, 1,... and/or the small wood flakes 3, 3,... are crushed in the width direction so as to split along the fiber direction (first length direction), and the small wood flakes 1, 1,... and/or the small wood flakes 3, 3,... Compared to the thin pieces 1, 1, . . . , it is possible to make the very small wooden pieces 2, 2, . . . which are more elongated. In other words, the very small wooden piece 2 has a second length (width) d2 smaller than the small wooden piece 1. In addition, in the further crushing step in the manufacturing process P3, the small wood flakes 1, 1,... and/or the small wood flakes 3, 3,... are also crushed in the first length direction. As a result, the very small wooden piece 2 becomes a thin piece that has not only the second length (width) d2 but also the first length d1 smaller than the small wooden piece 1.

In addition, as another method, the small wooden flakes 3, 3, . . . may be sorted by a mesh of Φ2, for example, and those that pass through the mesh may be used as the very small wooden flakes 2, 2, .

In this way, the small wood flakes 1, 1,... formed in the small wood flake manufacturing process P2 and the removed small wood flakes 3, 3,... are used to crush these small wood flakes 1, 3,... By further passing through the step of separating or the step of classifying, the very small wood flakes 2, 2,... having the first length d1 and/or second length (width) d2 smaller than the small wood flakes 1, 1,... It can be easily manufactured.

Note that the very small wood flakes 2, 2, ... obtained in the above-mentioned further crushing step may be passed through a sieve or the like (for example, a mesh of Φ2) to sort (classify) the very small wood flakes 2, 2, .... As a result, the large number of tiny wooden pieces 2, 2, . . . become fine and uniform in size and shape. Through the above steps, extremely small wooden pieces 2, 2, . . . are manufactured.

(Adhesive application process P3)
In the small wood flake production process P2 and the small wood flake production process P6, a large number of small wood flakes 1, 1, ... and very small wood flakes 2, 2, ..., which are fine and uniform in size and shape, are obtained by sorting. After that, an adhesive application step P3 is carried out, and the small wooden pieces 1, 1, . . . and the very small wooden pieces 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, a melamine resin, or a natural adhesive may be used. Further, a commonly used water repellent may be used together with the adhesive.

(Matt forming process P4)
Next, as shown on the left side of FIG. 11, first, a large number of tiny wooden pieces 2, 2, ... coated with the adhesive were assembled in the thickness direction with or without orientation in the fiber direction. By laminating (piling up) them to a predetermined thickness (height) in this state, a mat C1 (second aggregate) consisting only of the very small wooden pieces 2, 2, . . . is formed. Next, on the formed mat C1, a large number of small wood flakes 1, 1, ... coated with the adhesive are assembled in the thickness direction, with or without orientation in the fiber direction. By laminating them to a predetermined thickness, a mat B1 (first aggregate) consisting only of the small wood flakes 1, 1, . . . is formed. Finally, on the formed mat B1, a mat C1 composed only of the very small wooden pieces 2, 2, . . . is formed in the same manner as described above. In this way, the mat C1, the mat B1, and the mat C1 are sequentially laminated to form a three-layered laminated mat A1.

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 wood material layer B and each of the second wood material layers C to the entire wood laminated board Am is a desired ratio. For example, the ratio of the thickness of each second wood layer C to the entire wood laminate board Am is 15% (second wood layer C: first wood layer B: second wood layer C = 15:70: 15), and when forming a wood laminated board Am with a thickness of 4 mm, first, the thickness t is 0.2 mm so that the thickness (height) of the mat C1 is about 5 mm. Stack the very small wooden pieces 2, 2... Subsequently, small wooden pieces 1, 1, . . . having a thickness t of 0.2 mm are stacked on the mat C1 so that the thickness of the mat B1 is about 24 mm. Finally, the very small wooden pieces 2, 2, . . . are stacked on the mat B1 so that the thickness of the mat C1 is about 5 mm. In this way, the thickness (height) of the three-layer laminated mat A1 consisting of the mats C1, B1, and C1 is about 34 mm.

(Heat pressure process P5)
The laminated mat A1 is first pressed and compacted a little, as is done with ordinary wooden boards, and then carried into a hot press machine and set between hot plates. The laminated mat A1 is compressed by hot-pressing at a predetermined pressure and temperature using a hot-pressing machine, and is integrally molded by curing the adhesive. In this way, the wood laminated 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 wood laminated board Am of, for example, 4 mm, and the thickness is compressed to 1/10. The pressing temperature for the hot press treatment is not particularly limited, but is, for example, 100 to 180°C. The press pressure involved in the hot press treatment is, for example, 2 to 4 N/mm ² and the pressing time is, for example, 1 to 2 minutes. The pressing time varies depending on the thickness of the wood laminated board Am, and may take less than 1 minute or more than 2 minutes. Further, before the hot press treatment using the hot press apparatus, preliminary heating treatment using a heating apparatus may be performed.

In addition, the small wood flakes 1, 1, ... and the smaller wood microfine pieces 2, 2, ... have their knots removed and are kept within a fine range of size without variation. Because of the sagging, mats B1 and C1 each become homogeneous. That is, the entire laminated mat A1 becomes homogeneous, thereby eliminating variations in the strength of the wood laminated board Am. In other words, in a strand board that uses large strands (cut pieces), for example, uneven mats including knots may produce thin, low-strength areas in spots, resulting in variations in strength, but this is eliminated. Moreover, the thinner the small wooden pieces 1, 1, . . . , the higher the homogeneity of the mat B1, and the greater the strength of the wooden laminated board Am. In general, strand board using large strands (cuttings) can increase the strength, but in the present invention, the wood flakes 1 are thinner and smaller than the cuttings (wooden flakes after cutting) and are made smaller by crushing. It serves both the homogeneity and strength of the laminated board Am.

Further, the small wood flakes 1, 1, . . . are small and uniform in size, and gaps are uniformly formed between the small wood flakes 1, 1, . . . in the mat B1. Similarly, the tiny wood flakes 2, 2,... are smaller and more uniform in size than the tiny wood flakes 1, 1,..., and in the mat C1, there are gaps between the tiny wood flakes 2, 2,... Uniformly formed. Therefore, even if the small wood flakes 1, 1, ... of mat B1 and the very small wood flakes 2, 2, ... of mat C1 are hot-pressed while still containing a relatively large amount of moisture, the moisture will evaporate. The generated steam smoothly escapes from the mat B1 and the mat C1. That is, as shown on the left side of FIG. 11, within the mat B1, there are many minute voids between the mutually adjacent small wooden pieces 1, 1, . . . . Similarly, within the mat C1, there are many minute voids between the mutually adjacent tiny wooden pieces 2, 2, . . . . These voids communicate not only in the fiber direction and the direction perpendicular to the fibers of the small wood flakes 1, 1, . . . and the very small wood flakes 2, 2, . . . but also in the thickness direction. Further, these voids are continuous not only within the mat B1 and the mat C1, but also between the mat B1 and the mat C1, and are three-dimensionally continuous throughout the laminated mat A1. Therefore, punctures are less likely to occur when the pressure on the wood laminated board Am is stopped.

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

Note that the density of the first wood material layer B and the density of each second wood material layer C may be approximately the same or may be different. The densities of the wood material layers B and C are preferably different from the viewpoint of preventing punctures during molding. When the first wood material layer B and each second wood material layer C have different densities, the difference in density between both layers B and C is, for example, 400 kg/m ³ or more. Further, the relationship in density between the first wood material layer B and each second wood material layer C is not particularly limited, and even if the density of the first wood material layer B is higher than the density of each second wood material layer C, It can be good or low. From the perspective of improving the surface smoothness and color tone/color homogeneity of the wood laminated board Am, each second wood layer C is a high-density wood layer with a higher density than the first wood layer B. preferable.

In addition, as shown on the right side of FIG. 11, the wood laminated board Am has a large number of three-dimensionally continuous minute voids inside the first wood layer B and each second wood layer C ( Remaining). Therefore, the wood laminated board Am also has excellent breathability.

(Other processes)
The method for manufacturing the wood laminated board Am includes, as other steps, after the heat-pressing step P5, curing the wood laminated board Am to an equilibrium moisture content, and then grinding the second wood material layer C as the front and back surfaces with a sander; It may also include a finishing step to adjust the final thickness. A commonly used sander can be used, such as #150 sander. By going through this finishing step, a wood laminated board Am with even more excellent surface properties can be obtained.

Therefore, the wood laminated board Am of this embodiment can have the following effects.

The wood laminated board Am is composed of two types of small wood flakes 1 and very small wood flakes 2 of different sizes within the same thickness range. Specifically, the wood laminated 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 is formed by laminating a large number of small wood flakes 1, 1, ... having an aspect ratio (d1/d2) of 1 to 80 in an aggregated state and forming a single layer by adhesion and integration; Two second wood material layers C, C are formed by laminating a large number of very small wood flakes 2, 2,..., which are smaller in area than the flakes 1, 1,... into a single layer by adhesion and integration. The second wood material layers C and C are arranged on both sides of the first wood material layer B, and are configured into three layers by adhesion and integration.

That is, the first wood material layer B that constitutes the core layer of the wood laminated board Am is constructed in the same manner as the wood board As. Therefore, not only the strength of the first wood material layer B (that is, the wood laminated board Am) is increased, but also warping due to moisture absorption and release is less likely to occur, and good dimensional stability comparable to that of South Sea wood plywood can be obtained. In addition, the two second wood layers C and C constituting the front and back layers of the wood laminate board Am have a larger area (specifically, a first length d1 and a second length Since the large number of tiny wooden thin slices 2, 2, etc. with a small width (at least one dimension of the width d2) are arranged in a more uniform size, there are no large irregularities on the surface of the wooden board like in a normal OSB. This does not occur, and the wood laminated board Am has even better surface properties, and has the same excellent surface properties as MDF. In addition, mat B1 and mat C1, which are aggregates of a large number of small wood flakes 1, 1, ... and very small wood flakes 2, 2, ... of uniform size, respectively, are used as mat C1, mat B1, and mat C1. Since they are laminated and integrated in this order, their manufacture becomes easy.

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

Further, the average value of the thickness of the very small wooden pieces 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 /d2) of 5 to 10, the surface properties of each second wood material layer C, that is, the wood laminated board Am are further improved.

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

FIG. 12 illustrates 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 has superior dimensional stability, anisotropy, surface smoothness, and color tone and color uniformity compared to lauan plywood. Furthermore, compared to OSB, the wood laminated board Am has uniform bending young in the vertical and horizontal directions, and has good anisotropy in dimensional stability, smoothness in surface properties, and color tone/color homogeneity. That is, the wood laminated board Am has high strength and excellent dimensional stability and surface properties. In addition, the wood laminated board Am not only has the above characteristics, but also has the above-mentioned characteristics, compared to a single-layer wood board (in other words, the first wood layer B) consisting only of small wood flakes 1, 1,... , it can be said that it is a wooden board that specializes in surface properties.

<Other embodiments>
In the above embodiment, the wooden board As (in the second embodiment, the first wooden material layer (core layer) B) is made by crushing the wooden flakes cut from the log (wooden flakes after cutting). Although the present invention is made up of small wood flakes 1 that have become smaller in size, the present invention can also be made of wood flakes that have been cut from logs (cut wood flakes).

In the above embodiment, both the wood flake production process P1 and the small wood flake production process P2 have a classification process, but in the present invention, only one of the processes P1 and P2 includes a classification process. The classification step may not be included in either of steps P1 and P2. From the viewpoint of further improving not only the strength but also the dimensional stability and surface properties of the wooden board As, it is preferable that the process P1 or P2 has a classification process, and the process P2 has a classification process. is more preferred, and it is even more preferred that both steps P1 and P2 include a classification step.

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

As Wooden board Am Wooden laminated board (wooden board)
A1 Mat B 1st wood material layer B1 Mat C 2nd wood material layer C1 Mat P1 Wood flake production process P2 Small wood flake production process P3 Adhesive application process P4 Mat forming process P5 Heat pressing process P6 Tiny wood flake production process 1 Wood Small flake 1a Fiber 2 Very small wood flake 2a Fiber t Thickness d1 First length d2 Second length

The present invention relates to a wooden board.

In general, South Sea plywood such as lauan plywood is well known and widely used as an existing wood board. However, in recent years, it has become difficult to obtain South Sea plywood due to the depletion of raw materials and the prevention of environmental damage, and efforts are being made to replace it with other wood boards.

Plywood made from domestically produced coniferous trees has no problem in terms of raw material depletion, but due to its lack of surface properties, it is limited to applications focused on strength.

There is no problem with OSB, PB (particle board), and MDF as raw materials. However, although OSB has high strength, there is a problem in that its surface properties are insufficient. PB is cheap, but has the problem of lacking strength. Although MDF has good surface properties, it does not have sufficient dimensional stability. Furthermore, OSB, PB, and MDF have a disadvantage in that they have a higher density than South Sea plywood.

As described above, currently there is no wood board that satisfies multiple 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, those shown in Patent Documents 1 to 4 have been proposed. The wooden boards shown in Patent Document 1 and Patent Document 2 include a core layer made of a large number of wood flakes, and a surface layer laminated on at least one side of the core layer and made of a large number of wood flakes. It is. In the wooden 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. It is proposed that.

On the other hand, in the technology shown in Patent Document 3, a fiber mat is pressure-bonded to the surface of plywood, OSB, laminated wood, etc., and this fiber mat is compressed to create a high-density fiber layer. I'm trying to fill in the dents on the surface.

In addition, the floor decorative material shown in Patent Document 4 has a structure in which a moisture-proof film with a moisture permeability of 7 g/m ^2.24 hours or less is laminated on the back side of a wood base material such as MDF, so that the front side has a moisture-permeable layer. Even if a low decorative sheet is applied, warping and bending due to the magnitude of dimensional changes are suppressed.

Japanese Unexamined Patent Publication No. 7-47514 Japanese Patent Application Publication No. 7-76004 JP 2019-31104 Publication JP 2019-107894 Publication

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

In addition, the wood 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 difficult to reduce the thickness of the board. There are limits. Further, dimensional changes due to moisture absorption cannot be suppressed.

Furthermore, in the decorative material of Patent Document 4, 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 the above points, and its purpose is to provide high strength, excellent dimensional stability and surface quality, and to improve manufacturing efficiency by applying improved technology to a wooden board with a structure in which a large number of wood flakes are laminated. The object of the present invention is to make it possible to easily obtain a wooden board (base material).

In order to achieve the above object, this invention uses wood flakes whose size including thickness is limited to a microscopic range, compared to cut pieces that are normally used as constituent materials of OSB. Small wood flakes whose size is further limited to a very small range are used as the constituent material, and a large number of these small wood flakes are laminated together in an aggregated state to form a wood board.

In addition, in this invention, a core layer and a front and back layer are laminated and integrated on the front and back surfaces of the wooden board, the wood layer is made of very small wood flakes whose size is further limited to a microscopic range. Made of wood laminated board.

In this specification, the term "cutting piece" refers to a piece cut from logs for OSB use, and a piece commonly used as a constituent material of OSB. The "wooden flakes" according to the present invention are those cut from logs in the same way as "cuttings", but are thinner and smaller flakes that are outside the normal thickness range of "cuttings". . A "small wood flake" according to the present invention refers to a thin flake smaller than the "wood flake" within the same thickness range as the "wood flake".

Specifically, the first invention is directed to a wooden board formed by laminating a large number of small wooden pieces having front and back surfaces along the fiber direction in a collective state and bonding them together. The density of this wood board is 500 kg/m ³ or more and 800 kg/m ³ or less, and the small wood flakes constituting the wood board have an area of 6 cm ² or less on the front and back surfaces, and a thickness between the front and back surfaces. The fiber length is 0.05 mm or more and 0.35 mm or less, and the fiber direction is randomly oriented .

Similar to the first invention, the second invention is directed to a wooden board formed by laminating a large number of small wooden pieces having front and back surfaces along the fiber direction in a collective state and bonding them together. The density of this wood board is 500 kg/m ³ or more and 800 kg/m ³ or less, and the small wood flakes constituting the wood board have an area of 6 cm ² or less on the front and back surfaces, and the first The aspect ratio defined by length/second length along the fiber orthogonal direction perpendicular to the fiber direction is 4 to 80, and the fiber direction is randomly oriented .

In the first or second invention, the wooden board has a large number of small wooden flakes having an area of 6 cm ² or less and a thickness of 0.05 mm or more and 0.35 mm or less, or an aspect ratio of 4 to 80. It is constructed by laminating them together and bonding them together. The thickness, first length, and second length of the small wood flakes are all average values.

Specifically, the wood board is obtained by pulverizing wood flakes having a specific thickness obtained in the P1 step described below in a first direction of the wood flakes and in a second direction orthogonal to the first direction in the P2 step also described below. It is composed of small wood flakes of only one type of size, and the area of the front and back surfaces of the small wood flakes is within a narrow range of 6 cm ² or less, so the variation in area of the large number of small wood flakes is small. It becomes uniform in area (size). In addition, the thickness of small wood flakes is extremely thin and falls within a certain range, or the aspect ratio defined by average first length/average second length is also within a certain range, so wood boards have a constant shape. Small wood flakes arranged within a certain range gather together to form a homogeneous product. Further, the fiber directions of the large number of small wood flakes are randomly oriented, and the density of the obtained wood board is 500 kg/m 3 or more and ⁸⁰⁰ kg/m ³ or less. Therefore, not only does the strength of the wooden board become higher, but it also becomes less prone to warping due to moisture absorption and release, and can achieve good dimensional stability comparable to that of South Sea plywood. Furthermore, since the large number of small wood flakes are uniform in thickness and shape, the surface of the wood board does not have large irregularities unlike normal OSB, and the wood board has excellent surface properties. Furthermore, since a large number of small wooden pieces of uniform size are assembled and laminated, manufacturing thereof is also facilitated.

A third or fourth invention is directed to a wood board according to the first or second invention, in which wood layers are laminated and integrated on the front and back surfaces of the wood board. The wood layers constituting the front and back layers of this wood laminated board are characterized in that very small wood flakes having an area smaller than the above-mentioned small wood flakes are laminated in a cluster and bonded together. Note that the area refers to a value obtained by multiplying the first length and the second length, and refers to the area of the front and back surfaces along the fiber direction.

In the third or fourth aspect of the present invention, the wooden laminated board includes a wooden board constituting the core layer and a wooden material layer constituting the front and back layers, which are laminated together. The wood material layer is constructed by laminating a large number of very small wood flakes whose area is smaller than that of the small wood flakes in an aggregated state and bonding them together.

In this way, wood laminated boards are made by grinding wood flakes with a specific thickness obtained in the P1 process described below in two different sizes in the first and second directions of the wood flakes in the P2 process and P6 process, which will also be described later. It is composed of small woody flakes. Since the wood laminated board includes a wood board made of small wood flakes in the core layer, the same effect as the wood board of the first invention is achieved. Furthermore, the wood laminated board is made up of a large number of very small wood flakes with an area smaller than the small wood flakes, and the wood layer is laminated on both sides of the wood board to form the front and back layers. No large irregularities occur on the surface, and the surface properties can be further improved, and the material has excellent surface properties similar to MDF. In addition, the wood laminated board is an aggregate made up of many small wood flakes of uniform size, an aggregate made of a large number of small wood flakes of uniform size, and an aggregate made of very small wood flakes of uniform size. Since they are sequentially laminated and integrated, manufacturing is also facilitated.

A fifth invention is a wood board (wood laminated board) according to the third or fourth invention, wherein each wood layer has a thickness ratio of 5% to 40% of the entire wood board (wood laminated board). characterized by something. This makes it possible to achieve both strength and surface properties of the wood laminated board .

A sixth invention provides the wooden board according to any one of the first to fourth inventions, wherein the root mean square height Sq on the surface is 0.005 μm or more and 0.015 μm or less, or the arithmetic mean height Sa on the surface is 0.005 μm or more and 0.015 μm or less. 0.002 μm or more and 0.007 μm or less. This further improves the surface properties of the wooden board. In this specification, the surface quality of a wooden board refers to the surface quality of a wooden board that has been adjusted to a product thickness using, for example, a #150 sander.

As explained above, according to the present invention, a wooden board is formed by laminating a large number of small wood flakes having front and back surfaces along the fiber direction and bonding them together, and the surface of the small wood flakes is By setting the area of the back side to be 6 cm2 ^or less and the thickness to be 0.05 mm or more and 0.35 mm or less, or the aspect ratio defined by the first length/second length to be 4 to 80, a large number of small wood flakes can be It has a uniform size with little variation, making it possible to increase the strength of the wooden board, and it also has good dimensional stability and surface properties comparable to South Sea plywood, making it easy to make the wooden board. can be manufactured.

FIG. 1 is a sectional view of a wooden board according to a first embodiment of the present invention. FIG. 2 is an enlarged sectional view of a main part of the wooden board according to the first embodiment. FIG. 3 is an enlarged perspective view schematically showing small wooden pieces 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 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 pieces. 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 sectional view of a wooden board according to a second embodiment of the present invention. FIG. 8 is an enlarged sectional view of a main part of a wooden board according to a second embodiment. FIG. 9 is an enlarged perspective view schematically showing a very small wooden piece constituting the wooden material layer according to the second embodiment. FIG. 10 is a diagram showing a manufacturing process of a wooden board according to the second embodiment. FIG. 11 is an enlarged sectional view showing a state in which a wooden board according to the second embodiment is hot-pressed from a mat that is an aggregate of small wooden flakes and 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.

Hereinafter, embodiments of the present invention will be described in detail based on the drawings. The following description of the embodiments is merely illustrative in nature and is in no way intended to limit the present invention, its applications, or its uses.

[First embodiment]
<Wood board>
FIG. 1 shows a wooden board As according to a first embodiment of the present invention. This 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, for example. Thin wood boards As with a thickness of 3 mm or more and less than 6 mm are used, for example, as inner wall materials for loading beds of vehicles such as trucks, base materials for cushion floors constructed indoors, decorative surface materials, and interior building materials (riseers). It is constructed as an interior material such as panels (boards, etc.). The medium-thick wood 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 installed indoors, a floor base material for shoes, a doorway construction material, etc. In this way, the wood board As is used as a substitute for the existing plywood for the base plate. This wooden board As will be explained in detail.

As shown in an enlarged view in FIG. 2, the wooden board As is made up of a large number of small wooden pieces 1, 1,... having front and back surfaces along the fiber direction, which are laminated together and bonded together. The small wood flakes 1, 1, . . . have one type of thickness.

To explain the small wood flakes 1, as shown in an enlarged view in FIG. 3, the thickness t of the small wood flakes 1 is from 0.05 mm to 0.35 mm, preferably from 0.10 mm to 0.30 mm, Preferably it is 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 thin pieces 1, 1, . . . having a thin thickness t. The thickness t of the small wood flakes 1 is an average value. In other words, the small wood flake 1 is a strand (also referred to as a cut piece in the present invention) that is normally used as an element (constituent material) of a general OSB, and generally has a thickness of about 0.6 mm to 1.5 mm. However, it is a thinner flake than that.

In addition, the small wood flakes 1 have an average value 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 one length d1/average second length d2 is 1 to 80. That is, the small wooden piece 1 may be square or elongated (rectangular). When the small wood flake 1 has an elongated shape, the first length d1 is the longitudinal dimension (length), and has fibers 1a, 1a, . is the dimension in the fiber direction. Further, the second length d2 is a dimension (width) in the lateral direction, and is, for example, a dimension in the direction perpendicular to the fibers along a direction orthogonal to the fiber direction. The aspect ratio is preferably 2 to 70, more preferably 3 to 55, and still more preferably 4 to 40. As will be described later, the small wood flakes 1, although not shown, are wood flakes that have been cut from raw wood (also referred to as post-cut wood flakes) and have been crushed into smaller pieces. To define something different from a wood flake, the wood flake after cutting is referred to as a "small wood flake."

The area of the front and back surfaces of the small wooden piece 1 (the 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. Further, the lower limit of the area is, for example, 0.5 cm ² or more.

The tree species used for the small wood flakes 1, 1, . . . are not particularly limited, and, for example, South African trees and broad-leaved trees may be used, or other tree species may be used. For example, there are firs such as cedar, cypress, and Douglas fir, acacia, aspen, poplar, pine (hard pine, soft pine, radiata pine, etc.), birch, and rubber (rubber tree), but it is limited to these tree species. Furthermore, various tree species can be used. Various tree species include Sakhalin pine, Japanese larch, Ezo pine, Spanish mackerel, Japanese cypress, Japanese cypress, Japanese cypress, toga, Japanese pine, various pines, paulownia, maple, birch (white birch), shii, beech, Japanese oak, Japanese fir, Japanese oak, oak, camphor tree, and zelkova. Domestic materials such as rice cypress, rice cypress, rice cedar, rice fir, spruce, rice toga, redwood, etc., North American materials such as agathis, terminaria, lauan, meranti, juncon, chamelele, kalampayan, amberoi, melina, teak, apitong Any material can be used, including South Sea woods such as , Sengon Laut, balsa, cedro, mahogany, lignum vitae, acacia mangium, Mediterranean pine, bamboo, kolyang, and other foreign woods such as chameleon.

Regarding the physical properties of the small wood flakes 1, the density thereof 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. If the density is less than 250 kg/ ^m3 , the thickness of the mat required to form the wood board As of the same density and strength will increase, and the press pressure related to the hot press treatment in the press forming process will be increased. It is necessary to increase it.

Although the density of the small wood flakes 1 may exceed 800 kg/m ³ , it is difficult to easily obtain such small wood flakes 1. 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 small wood flakes 1 exceeding 800 kg/m ³ can be easily obtained.

Further, the moisture content of the small wood flakes 1 is preferably about 2 to 20%, more preferably 2 to 8%. When the water content is less than 2%, it takes time for softening in the hot press treatment in the press molding process, resulting in a long press time and a risk of a decrease in strength.

In addition, if the moisture content of the small wood flakes 1 exceeds 20%, it will take time to heat and compress during the hot press process, and furthermore, there is a risk that the curing of the adhesive will be inhibited and the strength will decrease. .

In the wood board As, the fiber direction (length direction) of the large number of small wood flakes 1, 1, ..., which is the direction along the fibers 1a, 1a, ..., may be oriented in the reference direction, This fiber orientation is not essential, and the fiber directions may be randomly oriented. Furthermore, the fact that the fiber direction (length direction) is oriented in the reference direction means that the fibers 1a, 1a, . . . of all the small wood flakes 1, 1, . In other words, the fiber directions of the oriented small wood flakes 1, 1, . . . are not limited to being parallel to each other. Some of the small wood flakes 1, 1,... may include small wood flakes 1, 1,... whose fiber direction is inclined to some extent (for example, about 20 degrees) with respect to the reference direction.

<Manufacturing method of wood board>
Next, a method for manufacturing the small wood flakes 1 and a method for manufacturing the wood board As from the small wood flakes 1 will be explained with reference to FIG. 4. The method for producing the small wood flakes 1 includes a wood flake manufacturing process P1 and a small wood flake manufacturing process P2. The method for manufacturing the wooden board As further includes subsequent adhesive application step P3, mat forming step P4, and hot pressing step P5.

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

At this time, each wooden flake is cut so that the fibers appear in a straight line on the front and back surfaces, and the cut thickness is the thickness t of the small wooden flake 1. In the subsequent steps, basically the thickness t of the small wood flake 1 does not change from the thickness of the wood flake after cutting, and the thickness of the wood flake after cutting becomes the thickness t of the small wood flake 1. be.

The cut wood flakes obtained in this step P1 are passed through a sieve (for example, a mesh with a diameter of 5 mm or more), and the size of the cut wood flakes is sorted (classified) (classification step). In some cases, wood flakes of a size comparable to the small wood flakes 1, 1, ... obtained after passing through the flake manufacturing process P2 (included in the size range of the first small wood flakes 1, 1, ...) are obtained. be. In that case, the wood flakes can be used as the small wood flakes 1, 1, . . . in the adhesive application process P3 without being subjected to the small wood flake manufacturing process P2.

(Small wood flake manufacturing process P2)
Next, after the above-mentioned cutting, the wood flakes classified as necessary (wood flakes after cutting) are crushed using a crusher that does not use a blade such as a hammer mill, pin mill, or jet mill, or a blade that does not use a blade such as a knife flaker or a cutter mill. The wood flakes are crushed using a machine and made smaller than the size of the wood flakes immediately after cutting in the direction orthogonal to the fibers, thereby forming small wood flakes 1, 1, . . . that constitute the wood board As. At this time, by crushing the wood flakes in the width direction so as to split them along the fiber direction (lengthwise direction) after cutting, small elongated wood flakes 1, 1, . . . can be produced. In other words, if a force (impact) is applied to a wood flake after cutting along a direction perpendicular to the fiber direction, it will not easily break, but if a force is applied parallel to the fiber direction, it will easily break. Even if the wood flakes are curled after cutting, they are divided into flat pieces by crushing. Note that the direction of the force applied to the wood flakes after cutting is not limited to the direction parallel to the fiber direction. When a force is applied in a random direction to a wood flake after cutting, the wood flake after cutting usually breaks from the part where the force is weaker (it tends to break in the direction of weaker force). The force that connects each fiber of a wood flake after cutting (force in the direction perpendicular to the fibers) is overwhelmingly weaker than the force in the fiber direction, so if you crush the wood flake in a random direction after cutting using the general crusher mentioned above, (When force is applied), the wood flakes after cutting are broken along the fiber direction and shortened in the direction perpendicular to the fibers, yielding small elongated wood flakes 1, 1, . . . .

Furthermore, even if there are wood knots in the wood flakes after cutting, the knots are more brittle than other parts, so the knots are turned into powder by pulverization and removed in a subsequent classification process.

In addition, in the case of a crusher that uses blades, there is a risk that the wood flakes may be unintentionally crushed in the direction perpendicular to the fibers after cutting, but in the case of a crusher that does not use blades, this risk is reduced. It is preferable to crush the wood flakes after cutting using a crusher that does not use a blade.

In this way, instead of just the one-step cutting process, by adding a crushing process and going through a two-step process, the cut wood flakes, which are thinner and smaller than the cut pieces, can be cut into knots of the required size. It is possible to easily produce high-strength small wood flakes 1, 1, . . . without parts.

A classification step may be included in which the small wood flakes 1, 1, ... obtained in the above-mentioned crushing step are passed through a sieve or the like, and the sizes of the small wood flakes 1, 1, ... are sorted (classified). As a result, the large number of small wood flakes 1, 1, . . . become fine and more uniform in size and shape. The small wood flakes 1 are manufactured by the above steps.

(Adhesive application process P3)
In the small wood flake manufacturing process P2, when a large number of small wood flakes 1, 1, ... which are fine and uniform in size and shape are obtained by sorting, an adhesive application process P3 is performed, and the small wood flakes 1 are , 1, ... are carried into an adhesive coating device and adhesive is applied thereto. 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 also be used. . Further, a commonly used water repellent may be used together with the adhesive.

(Matt forming process P4)
Next, as shown on the left side of FIG. 5, a large number of small wood flakes 1, 1, ... coated with the adhesive are assembled in the thickness direction, with or without orientation in the fiber direction. A mat A1 of the small wood flakes 1, 1, . . . is formed by laminating (stacking) them to a predetermined thickness (height). For example, when forming a wooden board As with a thickness of 4 mm, small wooden pieces 1, 1 with a thickness t of 0.2 mm, Accumulate...

(Heat pressure process P5)
This mat A1 is carried into a hot press machine and set between hot plates, and the hot press machine heats the mat A1 at a predetermined pressure and temperature to compress it, and then hardens the adhesive to make it into one piece. Shape. In this way, the wooden board As shown in FIG. 1 is formed.

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

In addition, the knots of the small wood flakes 1, 1, ... have been removed, and the sizes are kept within a small range without variation, so they are homogeneous throughout the mat A1, and as a result, There is no variation in the strength of the wooden board As. In other words, in a strand board that uses large strands (cut pieces), for example, uneven mats including knots may produce thin, low-strength areas in spots, resulting in variations in strength, but this is eliminated. Moreover, the thinner the small wooden pieces 1, 1, . . . , the higher the homogeneity of the mat A1 becomes, and the stronger the wooden board As becomes. In general, strand board using large strands (cuttings) can increase the strength, but in the present invention, the wood flakes 1 are thinner and smaller than the cuttings (wooden flakes after cutting) and are made smaller by crushing. It serves both the homogeneity and strength of the board As.

Furthermore, the small wood flakes 1, 1,... are small and uniform in size, and gaps are uniformly formed between the small wood flakes 1, 1,... in the mat A1. Even if the small wood flakes 1, 1, . . . are hot-pressed while still containing a relatively large amount of moisture, the 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, in the mat A1, there are many minute voids between the mutually adjacent small wooden pieces 1, 1, . . . . These voids communicate not only in the fiber direction and perpendicular direction to the fibers of the small wood flakes 1, 1, . . . but also in the thickness direction, and are three-dimensionally continuous. Therefore, punctures are less likely to occur when the pressure on the wooden board As is stopped.

Through these steps, a wood board As having a density of 500 kg/m ³ or more and 800 kg/m ³ or less and a bending Young of 3.5 GPa or more and 7.0 GPa or less is formed. As shown on the right side of FIG. 5, this wooden board As has (remains) many three-dimensionally continuous minute voids inside thereof. Therefore, the wooden board As also has excellent breathability.

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

<Surface quality of wood board>
The wooden board As preferably has a root mean square height Sq of 0.005 μm or more and 0.015 μm or less on the surface, or an arithmetic mean height Sa of 0.002 μm or more and 0.007 μm or less on the surface. Note that the surface of the wooden board As refers to the surface of the wooden board As after the above-mentioned finishing step, for example, the surface of the wooden board As that has been 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 surface properties defined by ISO25178. That is, the wooden board As has excellent surface properties by controlling the parameters Sq and Sa that specify the surface properties within specific ranges.

The root mean square height Sq is a parameter that corresponds to the standard deviation of the distance from the average plane, and corresponds to the standard deviation of the 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 surface irregularities, and the better the surface properties. Specifically, if the thickness t of the small wooden flakes 1, 1, ... is 0.35 mm or less, the root mean square height Sq on the surface of the wooden board As will be about 0.005 μm or more and 0.015 μm or less, If the thickness t of the small wooden pieces 1, 1, ... is 0.25 mm or less (preferably 0.20 mm or less), the root mean square height Sq on the surface of the wooden board As is 0.005 μm or more and 0.008 μm or less Since the surface roughness is comparable to that of MDF, which has excellent surface properties, wooden board As has even better surface properties and is therefore preferable.

The arithmetic mean height Sa represents the average of the absolute values of the differences in height of each point with respect to the average 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 irregularities the surface has, and the better the surface properties. Specifically, if the thickness t of the small wooden flakes 1, 1, ... is 0.35 mm or less, the arithmetic mean height Sa on the surface of the wooden board As is about 0.002 μm or more and 0.007 μm or less, and the wood If the thickness t of the small flakes 1, 1, ... is 0.25 mm or less (preferably 0.20 mm or less), the arithmetic mean height Sa on the surface of the wooden board As will be about 0.002 μm or more and 0.005 μm or less. Since the surface roughness is comparable to that of MDF, which has excellent surface properties, wooden board As has even better surface properties and is therefore preferable.

Note that the surface quality of the wooden board As is not limited to the root mean square height Sq and the arithmetic mean height Sa, but for example, the skewness Ssk, the maximum valley depth Sv, the maximum peak height Sp, and the maximum valley depth Sv. It may be specified by the maximum height Sz indicating the sum, the kurtosis Sku, etc.

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

The wooden 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. The ratio of the second length d2 along the direction perpendicular to the fibers to the average value: 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 wood flakes 1, 1, . . . are laminated together in a single layer by adhesion and integration.

That is, the single-layer wooden board As is composed of only one type of small wood flakes 1, 1,..., and the thickness t of the small wood flakes 1, 1,... is extremely thin, ranging from 0.05 mm to 0.35 mm. Since the thickness falls within a narrow range of the following, the large number of small wood flakes 1, 1, . . . have a uniform thickness t with small variations in thickness t. In addition, since the aspect ratio (d1/d2) of the small wood flakes 1, 1, ... is within a certain range, the wood board As is made up of small wood flakes 1, 1, ... whose sizes are within a certain range. It becomes homogeneous. Therefore, not only the strength of the wooden board As is increased, but also warping due to moisture absorption and release is difficult to occur, and good dimensional stability comparable to that of South Sea wood plywood can be obtained. In addition, since the large number of small wooden flakes 1, 1, ... are uniform in size, there is no large unevenness on the surface of the wooden board unlike with normal OSB, and the wooden board As has excellent surface properties. It becomes something. Further, since a large number of uniformly shaped wood thin pieces 1, 1, .

In particular, if the average value of the thickness t of the small wooden flakes 1, 1, ... in the wooden board As is 0.15 mm or more and 0.25 mm or less, and the aspect ratio (d1/d2) is an elongated shape with an aspect ratio (d1/d2) of 4 to 40, , the dimensional stability and surface properties of the wooden board As are further improved.

FIG. 6 illustrates 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 has superior anisotropy in dimensional stability and color tone and color homogeneity in surface properties compared to lauan plywood. Furthermore, compared to OSB, wooden board As has uniform bending young in the vertical and horizontal directions, and has good anisotropy in dimensional stability, smoothness in surface properties, and color tone/color homogeneity. That is, the wooden board As has high strength and excellent dimensional stability and surface properties.

[Second embodiment]
<Wood board (wood laminated 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 also be called a wooden laminated board. Hereinafter, the wooden board Am will also be referred to as the wooden laminated board Am. Note that the configuration of the wooden board As other than the wooden layer constituting the wooden laminated board Am is the same as that of the first embodiment, so a detailed explanation will be omitted here. In addition, the same reference numerals are given to the same components as in the first embodiment, and the explanation thereof will be omitted.

The wood laminated 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. Thin type wood laminated 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 loading beds of vehicles such as trucks, as a base material for cushion floors installed indoors, as a decorative surface material, as an interior building material ( It is constructed as an interior material such as risers etc.). The medium-thick wood laminate board Am having a thickness of about 6 mm or more and 12 mm or less is used, for example, as a soundproof floor base material constructed indoors, a floor base material for shoes on, a doorway construction material, etc. In this way, the wood laminated board Am is used as an alternative material to the existing plywood for the base plate. Moreover, since the wood laminated board Am has surface properties similar to MDF, it can be suitably used as a decorative thin plywood.

The wood laminated board Am includes a first wood layer B and two wood layers (hereinafter also referred to as "second wood layers") C and C, and a second wood layer is formed on both sides of the first wood layer B. Material layers C and C are laminated and integrated. In other words, the first wood material layer B is interposed between the two second wood material layers C, C. That is, the first wood material layer B constitutes the core layer of the wood laminate board Am, and the two second wood material layers C and C constitute the front and back layers of the wood laminate board Am.

The ratio of the thickness of each second wood layer C to the entire wood laminate board Am is preferably 5% or more and 40% or less, more preferably 8% or more and 30% or less, and even more preferably 10% or more and 25% or less. be. That is, the ratio of the second wood layer C: the first wood layer B: the second wood layer C in the wood laminated board Am is preferably 5:90:5 to 40:20:40, more preferably 8:84: The ratio is 8 to 30:40:30, more preferably 10:80:10 to 25:50:25. By appropriately changing the ratio of the thickness of the first wood material layer B and each of the second wood material layers C, a wood laminated board Am that has both the necessary strength and excellent surface properties depending on the application can be obtained. .

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

(Second wood layer)
As shown in an enlarged view in FIG. 8, the second wood material layer C is made up of a large number of very small wood flakes 2, 2, ... having front and back surfaces along the fiber direction, which are laminated in an aggregate state and bonded together. , a large number of tiny wood flakes 2, 2, . . . have one type of thickness.

The very small wooden piece 2 is a thin piece that is smaller in size (the area of its front and back surfaces) than the small wooden piece 1. To explain in detail about the very small wooden flakes 2, as shown in an enlarged view in FIG. .30 mm or less, even more preferably 0.15 mm or more and 0.25 mm or less, still more preferably 0.15 mm or more and 0.20 mm or less. That is, the thickness t of the very small wooden piece 2 is equal to or smaller than the thickness t of the small wooden piece 1. As a result, the characteristics of the second wood layer C, that is, the characteristics of the wood laminated board Am, are determined by the very small wooden pieces 2, 2, . . . having a thin thickness t. The thickness t of the very small wooden slice 2 is an average value.

Further, the aspect ratio (d1/d2) of the very small wood flakes 2, which is defined similarly to the small wood flakes 1, is preferably 1 to 500. That is, the very small wooden piece 2 may have a square shape or an elongated shape (rectangular shape). When the very small wooden flake 2 has an elongated shape, the first length d1 is the longitudinal dimension (length), similar to the small wooden flake 1, and it has fibers 2a, 2a, . , is the fiber direction dimension in the direction along the fiber 2a. Further, the second length d2 is a dimension (width) in the lateral direction, and is, for example, a dimension in the direction perpendicular to the fibers along a direction orthogonal to the fiber direction. The aspect ratio is preferably 2 to 100, more preferably 3 to 12.5, even more preferably 5 to 10.

Note that the area of the front and back surfaces of the very small wooden flake 2 is not particularly limited as long as it is smaller than the area of the front and back surfaces of the small wooden flake 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 tree species used for the very small wood flakes 2, 2,... are not particularly limited, and the same tree species as the wood species used for the small wood flakes 1, 1,... may be used, or other tree species may be used. . Further, the tree species of the very small wood flakes 2, 2, . . . may be the same as or different from the tree species of the small wood flakes 1, 1, . From the viewpoint of easily producing the tiny wood flakes 2, 2,... using the small wood flakes 1, 1,..., the wood species of the tiny wood flakes 2, 2,... are the same as the wood species of the small wood flakes 1, 1,... Preferably they are the same.

Regarding the physical properties of the tiny wood flakes 2, the density thereof 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. If the density is less than 250 kg/ ^m3 , the thickness of the mat required to form the wood laminated board Am of the same density and strength will increase, and the press pressure related to the hot press treatment in the press molding process will increase. It is necessary to increase

Although the density of the very small wood flakes 2 may exceed 800 kg/m ³ , it is difficult to easily obtain such very small wood flakes 2. 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 it is possible to easily obtain the very small wood flakes 2 with a weight exceeding 800 kg/m ³ .

Further, the moisture content of the very small wooden flakes 2 is preferably about 2 to 20%, more preferably 2 to 8%.

In the second wood material layer C, a large number of very small wood flakes 2, 2, ... are oriented in the reference direction even if the fiber direction (length direction), which is the direction along the fibers 2a, 2a, ..., is oriented in the reference direction. However, this orientation of the fiber direction is not essential, and the fiber direction may be randomly oriented. Some of the very small wood flakes 2, 2, . . . may include those whose fiber direction is inclined to some extent (for example, about 20°) with respect to the reference direction.

<Manufacturing method of wood board (wood laminated board)>
Next, a method for producing the small wood flakes 1, 1,... and very small wood flakes 2, 2,..., and a method for producing the wood laminated board Am from these small wood flakes 1, 2,... will be explained with reference to FIG. . The method for producing the small wood flakes 1, 1, . . . includes a wood flake manufacturing process P1 and a small wood flake manufacturing process P2. The method for producing the very small wooden flakes 2, 2, . . . further includes a subsequent very small wood flake manufacturing step P6. The method for manufacturing the wood laminated board Am further includes subsequent adhesive application step P3, mat forming step P4, and hot pressing step P5.

(Wood flake manufacturing process P1)
Since the wood flake manufacturing process P1 is the same process as the wood flake manufacturing process P1 according to the first embodiment, detailed explanation will be omitted here. In the subsequent steps, basically the thickness t of the small wood flakes 1 and the very small wood flakes 2 does not change from the thickness of the wood flakes after cutting, and the thickness of the wood flakes after cutting remains unchanged. The thickness of the very small wooden piece 2 is t.

(Small wood flake manufacturing process P2)
Since the small wood flake manufacturing process P2 is also the same process as the small wood flake manufacturing process P2 according to the first embodiment, detailed explanation will be omitted here.

(Wood microscopic flake manufacturing process P6)
In the small wood flakes manufacturing process P2, from the small wood flakes 1, 1,... formed and the small wood flakes 3, 3,... (not shown) removed in the classification process of the small wood flakes 1, 1,... It is possible to obtain very small wood flakes 2, 2, . . . which are smaller in size than the small wood lamellas 1, 1, . Note that the small wood flakes 3 removed in the above classification process refer to small wood flakes other than the small wood flakes 1 formed in the small wood flake manufacturing process P2, and the size of the small wood flakes 1 (thickness t and refers to small wood flakes with at least one aspect ratio outside the range.

Specifically, the small wood flakes 1, 1, . . . and/or the small wood flakes 3, 3, . . . are further crushed using the same method as the small wood flake manufacturing process P2. As a result, the small wood flakes 1, 1,... and/or the small wood flakes 3, 3,... are crushed in the width direction so as to split along the fiber direction (first length direction), and the small wood flakes 1, 1,... and/or the small wood flakes 3, 3,... Compared to the thin pieces 1, 1, . . . , it is possible to make the very small wooden pieces 2, 2, . . . which are more elongated. In other words, the very small wooden piece 2 has a second length (width) d2 smaller than the small wooden piece 1. In addition, in the further crushing step in the manufacturing process P6 , the small wood flakes 1, 1,... and/or the small wood flakes 3, 3,... are also crushed in the first length direction. As a result, the very small wooden piece 2 becomes a thin piece that has not only the second length (width) d2 but also the first length d1 smaller than the small wooden piece 1.

In addition, as another method, the small wooden flakes 3, 3, . . . may be sorted by a mesh of Φ2, for example, and those that pass through the mesh may be used as the very small wooden flakes 2, 2, .

In this way, the small wood flakes 1, 1,... formed in the small wood flake manufacturing process P2 and the removed small wood flakes 3, 3,... are used to crush these small wood flakes 1, 3,... By further passing through the step of separating or the step of classifying, the very small wood flakes 2, 2,... having the first length d1 and/or second length (width) d2 smaller than the small wood flakes 1, 1,... It can be easily manufactured.

Note that the very small wood flakes 2, 2, ... obtained in the above-mentioned further crushing step may be passed through a sieve or the like (for example, a mesh of Φ2) to sort (classify) the very small wood flakes 2, 2, .... As a result, the large number of tiny wooden pieces 2, 2, . . . become fine and uniform in size and shape. Through the above steps, extremely small wooden pieces 2, 2, . . . are manufactured.

(Adhesive application process P3)
In the small wood flake production process P2 and the small wood flake production process P6, a large number of small wood flakes 1, 1, ... and very small wood flakes 2, 2, ..., which are fine and uniform in size and shape, are obtained by sorting. After that, an adhesive application step P3 is carried out, and the small wooden pieces 1, 1, . . . and the very small wooden pieces 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, a melamine resin, or a natural adhesive may be used. Further, a commonly used water repellent may be used together with the adhesive.

(Matt forming process P4)
Next, as shown on the left side of FIG. 11, first, a large number of tiny wooden pieces 2, 2, ... coated with the adhesive were assembled in the thickness direction with or without orientation in the fiber direction. By laminating (piling up) them to a predetermined thickness (height) in this state, a mat C1 (second aggregate) consisting only of the very small wooden pieces 2, 2, . . . is formed. Next, on the formed mat C1, a large number of small wood flakes 1, 1, ... coated with the adhesive are assembled in the thickness direction, with or without orientation in the fiber direction. By laminating them to a predetermined thickness, a mat B1 (first aggregate) consisting only of the small wood flakes 1, 1, . . . is formed. Finally, on the formed mat B1, a mat C1 composed only of the very small wooden pieces 2, 2, . . . is formed in the same manner as described above. In this way, the mat C1, the mat B1, and the mat C1 are sequentially laminated to form a three-layered laminated mat A1.

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 wood material layer B and each of the second wood material layers C to the entire wood laminated board Am is a desired ratio. For example, the ratio of the thickness of each second wood layer C to the entire wood laminate board Am is 15% (second wood layer C: first wood layer B: second wood layer C = 15:70: 15), and when forming a wood laminated board Am with a thickness of 4 mm, first, the thickness t is 0.2 mm so that the thickness (height) of the mat C1 is about 5 mm. Stack the very small wooden pieces 2, 2... Subsequently, small wooden pieces 1, 1, . . . having a thickness t of 0.2 mm are stacked on the mat C1 so that the thickness of the mat B1 is about 24 mm. Finally, the very small wooden pieces 2, 2, . . . are stacked on the mat B1 so that the thickness of the mat C1 is about 5 mm. In this way, the thickness (height) of the three-layer laminated mat A1 consisting of the mats C1, B1, and C1 is about 34 mm.

(Heat pressure process P5)
The laminated mat A1 is first pressed and compacted a little, as is done with ordinary wooden boards, and then carried into a hot press machine and set between hot plates. The laminated mat A1 is compressed by hot-pressing at a predetermined pressure and temperature using a hot-pressing machine, and is integrally molded by curing the adhesive. In this way, the wood laminated 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 wood laminated board Am of, for example, 4 mm, and the thickness is compressed to 1/10. The pressing temperature for the hot press treatment is not particularly limited, but is, for example, 100 to 180°C. The press pressure involved in the hot press treatment is, for example, 2 to 4 N/mm ² and the pressing time is, for example, 1 to 2 minutes. The pressing time varies depending on the thickness of the wood laminated board Am, and may take less than 1 minute or more than 2 minutes. Further, before the hot press treatment using the hot press apparatus, preliminary heating treatment using a heating apparatus may be performed.

In addition, the small wood flakes 1, 1, ... and the smaller wood microfine pieces 2, 2, ... have their knots removed and are kept within a fine range of size without variation. Because of the sagging, mats B1 and C1 each become homogeneous. That is, the entire laminated mat A1 becomes homogeneous, thereby eliminating variations in the strength of the wood laminated board Am. In other words, in a strand board that uses large strands (cut pieces), for example, uneven mats including knots may produce thin, low-strength areas in spots, resulting in variations in strength, but this is eliminated. Moreover, the thinner the small wooden pieces 1, 1, . . . , the higher the homogeneity of the mat B1, and the greater the strength of the wooden laminated board Am. In general, strand board using large strands (cuttings) can increase the strength, but in the present invention, the wood flakes 1 are thinner and smaller than the cuttings (wooden flakes after cutting) and are made smaller by crushing. It serves both the homogeneity and strength of the laminated board Am.

Further, the small wood flakes 1, 1, . . . are small and uniform in size, and gaps are uniformly formed between the small wood flakes 1, 1, . . . in the mat B1. Similarly, the tiny wood flakes 2, 2,... are smaller and more uniform in size than the tiny wood flakes 1, 1,..., and in the mat C1, there are gaps between the tiny wood flakes 2, 2,... Uniformly formed. Therefore, even if the small wood flakes 1, 1, ... of mat B1 and the very small wood flakes 2, 2, ... of mat C1 are hot-pressed while still containing a relatively large amount of moisture, the moisture will evaporate. The generated steam smoothly escapes from the mat B1 and the mat C1. That is, as shown on the left side of FIG. 11, within the mat B1, there are many minute voids between the mutually adjacent small wooden pieces 1, 1, . . . . Similarly, within the mat C1, there are many minute voids between the mutually adjacent tiny wooden pieces 2, 2, . . . . These voids communicate not only in the fiber direction and the direction perpendicular to the fibers of the small wood flakes 1, 1, . . . and the very small wood flakes 2, 2, . . . but also in the thickness direction. Further, these voids are continuous not only within the mat B1 and the mat C1, but also between the mat B1 and the mat C1, and are three-dimensionally continuous throughout the laminated mat A1. Therefore, punctures are less likely to occur when the pressure on the wood laminated board Am is stopped.

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

Note that the density of the first wood material layer B and the density of each second wood material layer C may be approximately the same or may be different. The densities of the wood material layers B and C are preferably different from the viewpoint of preventing punctures during molding. When the first wood material layer B and each second wood material layer C have different densities, the difference in density between both layers B and C is, for example, 400 kg/m ³ or more. Further, the relationship in density between the first wood material layer B and each second wood material layer C is not particularly limited, and even if the density of the first wood material layer B is higher than the density of each second wood material layer C, It can be good or low. From the perspective of improving the surface smoothness and color tone/color homogeneity of the wood laminated board Am, each second wood layer C is a high-density wood layer with a higher density than the first wood layer B. preferable.

In addition, as shown on the right side of FIG. 11, the wood laminated board Am has a large number of three-dimensionally continuous minute voids inside the first wood layer B and each second wood layer C ( Remaining). Therefore, the wood laminated board Am also has excellent breathability.

(Other processes)
The method for manufacturing the wood laminated board Am includes, as other steps, after the heat-pressing step P5, curing the wood laminated board Am to an equilibrium moisture content, and then grinding the second wood material layer C as the front and back surfaces with a sander; It may also include a finishing step to adjust the final thickness. A commonly used sander can be used, such as #150 sander. By going through this finishing step, a wood laminated board Am with even more excellent surface properties can be obtained.

Therefore, the wood laminated board Am of this embodiment can have the following effects.

The wood laminated board Am is composed of two types of small wood flakes 1 and very small wood flakes 2 of different sizes within the same thickness range. Specifically, the wood laminated 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 is formed by laminating a large number of small wood flakes 1, 1, ... having an aspect ratio (d1/d2) of 1 to 80 in an aggregated state and forming a single layer by adhesion and integration; Two second wood material layers C, C are formed by laminating a large number of very small wood flakes 2, 2,..., which are smaller in area than the flakes 1, 1,... into a single layer by adhesion and integration. The second wood material layers C and C are arranged on both sides of the first wood material layer B, and are configured into three layers by adhesion and integration.

That is, the first wood material layer B that constitutes the core layer of the wood laminated board Am is constructed in the same manner as the wood board As. Therefore, not only the strength of the first wood material layer B (that is, the wood laminated board Am) is increased, but also warping due to moisture absorption and release is less likely to occur, and good dimensional stability comparable to that of South Sea wood plywood can be obtained. In addition, the two second wood layers C and C constituting the front and back layers of the wood laminate board Am have a larger area (specifically, a first length d1 and a second length Since the large number of tiny wooden thin slices 2, 2, etc. with a small width (at least one dimension of the width d2) are arranged in a more uniform size, there are no large irregularities on the surface of the wooden board like in a normal OSB. This does not occur, and the wood laminated board Am has even better surface properties, and has the same excellent surface properties as MDF. In addition, mat B1 and mat C1, which are aggregates of a large number of small wood flakes 1, 1, ... and very small wood flakes 2, 2, ... of uniform size, respectively, are used as mat C1, mat B1, and mat C1. Since they are laminated and integrated in this order, their manufacture becomes easy.

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

Further, the average value of the thickness of the very small wooden pieces 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 /d2) of 5 to 10, the surface properties of each second wood material layer C, that is, the wood laminated board Am are further improved.

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

FIG. 12 illustrates 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 has superior dimensional stability, anisotropy, surface smoothness, and color tone and color uniformity compared to lauan plywood. Furthermore, compared to OSB, the wood laminated board Am has uniform bending young in the vertical and horizontal directions, and has good anisotropy in dimensional stability, smoothness in surface properties, and color tone/color homogeneity. That is, the wood laminated board Am has high strength and excellent dimensional stability and surface properties. In addition, the wood laminated board Am not only has the above characteristics, but also has the above-mentioned characteristics, compared to a single-layer wood board (in other words, the first wood layer B) consisting only of small wood flakes 1, 1,... , it can be said that it is a wooden board that specializes in surface properties.

<Other embodiments>
In the above embodiment, the wooden board As (in the second embodiment, the first wooden material layer (core layer) B) is made by crushing the wooden flakes cut from the log (wooden flakes after cutting). Although the present invention is made up of small wood flakes 1 that have become smaller in size, the present invention can also be made of wood flakes that have been cut from logs (cut wood flakes).

In the above embodiment, both the wood flake production process P1 and the small wood flake production process P2 have a classification process, but in the present invention, only one of the processes P1 and P2 includes a classification process. The classification step may not be included in either of steps P1 and P2. From the viewpoint of further improving not only the strength but also the dimensional stability and surface properties of the wooden board As, it is preferable that the process P1 or P2 has a classification process, and the process P2 has a classification process. is more preferred, and it is even more preferred that both steps P1 and P2 include a classification step.

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

As Wooden board Am Wooden laminated board (wooden board)
A1 Mat B 1st wood material layer B1 Mat C 2nd wood material layer C1 Mat P1 Wood flake production process P2 Small wood flake production process P3 Adhesive application process P4 Mat forming process P5 Heat pressing process P6 Tiny wood flake production process 1 Wood Small flake 1a Fiber 2 Very small wood flake 2a Fiber t Thickness d1 First length d2 Second length

Claims (7)

A wooden board formed by laminating a large number of small wooden pieces having front and back surfaces along the fiber direction in an aggregate state and bonding them together,
A wooden board characterized in that the small wooden pieces have an area of 6 cm ² or less on the front and back surfaces, and a thickness between the front and back surfaces of 0.05 mm or more and 0.35 mm or less. A wooden board formed by laminating a large number of small wooden pieces having front and back surfaces along the fiber direction in an aggregate state and bonding them together,
The small wood flakes have an area of 6 cm ² or less on the front and back surfaces, and have an aspect ratio defined by a first length along the fiber direction/a second length along the fiber direction perpendicular to the fiber direction. A wooden board characterized by a ratio of 4 to 80. The wooden board according to claim 1,
Wooden layers are laminated and integrated on the front and back sides of the wood board,
The wood board is characterized in that the wood layer is formed by laminating very small wood flakes whose area is smaller than the small wood flakes in an aggregated state and bonding them together. The wooden board according to claim 2,
Wooden layers are laminated and integrated on the front and back sides of the wood board,
The wood board is characterized in that the wood layer is formed by laminating very small wood flakes whose area is smaller than the small wood flakes in an aggregated state and bonding them together. The wooden board according to claim 3 or 4,
A wood board characterized in that a thickness ratio of the wood layer to the entire wood board is 5% or more and 40% or less. The wooden board according to any one of claims 1 to 4,
A wooden board having a density of 500 kg/m ³ or more and 800 kg/m ³ or less. The wooden board according to any one of claims 1 to 4,
A wooden board characterized in that the root mean square height Sq on the surface is 0.005 μm or more and 0.015 μm or less, or the arithmetic mean height Sa on the surface is 0.002 μm or more and 0.007 μm or less.