JP2022118559A - Woody board manufacturing method - Google Patents

Abstract

To provide a woody board A which is high in strength, excellent in size stability and surface nature, and easily manufactured.SOLUTION: A method for manufacturing a woody board A comprises: a woody thin piece manufacturing step P1 of cutting a raw wood to make a woody thin piece; a woody small thin piece manufacturing step P2 of crushing the woody thin piece to form woody small thin pieces 1 smaller than the woody thin piece; an adhesive application step P3 of applying an adhesive on the woody small thin pieces 1; a mat forming step P4 of stacking multiple adhesive-applied woody small thin pieces 1 in the state of being collected in a thickness direction to form mats of the woody small thin pieces 1; and a hot pressing step P5 of compressing and integrating the mats through a hot pressing process. Through the steps P1-P5, the woody board A is provided, which is formed by staking and adhesively integrating multiple woody small thin pieces 1 having front and rear surfaces in a fiber direction.SELECTED DRAWING: Figure 4

Description

TECHNICAL FIELD The present invention relates to a method for manufacturing a wooden board.

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

Plywood made from domestic coniferous trees poses no problem in terms of raw material depletion, but its surface properties are insufficient, so it is limited to applications that require special strength.

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

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

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

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

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

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

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

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

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

The present invention has been made in view of these points, and its object is to improve the wooden board structure in which a large number of wooden flakes are laminated, so that the wood flakes can be used only in a narrow and constant range of sizes. To obtain a wooden board which has high strength, is excellent in dimensional stability and surface properties, and is easy to manufacture.

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

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

Specifically, the first invention is directed to a method for manufacturing a wooden board in which a large number of small wooden flakes having front and back surfaces along the fiber direction are laminated in an aggregated state and bonded together. This manufacturing method comprises a wooden flake manufacturing process for cutting raw wood to produce wooden flakes, a small wooden flake manufacturing process for pulverizing the wooden flakes to form small wooden flakes smaller than the wooden flakes, and bonding to the small wooden flakes. an adhesive application step of applying an adhesive; a mat forming step of forming a mat of the small wood flakes by laminating a large number of small wood flakes coated with the adhesive while gathering them in the thickness direction; and a hot-pressing step of compressing and integrating by a hot-pressing process.

In the first aspect of the present invention, in the wooden flake manufacturing process, raw wood is cut to produce wooden flakes that are thinner and smaller than the cut pieces normally used as OSB constituent materials, and then in the wooden small flake manufacturing process, The wood flakes are crushed to form wood flakes that are smaller than the wood flakes. Since the small wooden flakes are produced through the two-step process in this manner, the small wooden flakes can be easily produced.

Further, in the adhesive application step, adhesive was applied to the small wood flakes formed in the above step, and then in the mat forming step, a large number of small wood flakes coated with the adhesive were assembled in the thickness direction. A mat of the small wood flakes is formed by laminating the wood flakes in a state, and finally, the mat is compressed and integrated by a hot-pressing process, so that a large number of small wood flakes are laminated in an aggregated state and integrated by adhesion. A wooden board is molded. Since the wooden board is manufactured through the three-step process after the two-step process of forming the small wooden flakes, the wooden board can be easily manufactured.

The wood board obtained in this way is made by crushing wood flakes having a specific thickness obtained in the wood flake manufacturing process in the fiber direction of the wood flakes in the wood flake manufacturing process. The thickness of the small wooden flakes is extremely thin, and a large number of small wooden flakes have a uniform thickness with little variation in thickness. In addition, since the length and width of the small wooden flakes are also within a certain range, the wooden board is made homogeneous by gathering the small wooden flakes of uniform size within a certain range. As a result, local defects and variations in density are greatly reduced, making it possible to stably develop the strength of the wooden board. In addition, warping due to moisture absorption and desorption is less likely to occur, and good dimensional stability comparable to that of plywood made of South Sea wood can be obtained. In addition, since a large number of small wooden flakes are uniform in size, the surface of the wooden board does not have large irregularities unlike ordinary OSB, and the wooden board has excellent surface properties. In addition, since a large number of small wooden flakes of uniform size are collected and laminated, the production thereof is facilitated.

A second aspect of the invention is characterized in that, in the method of manufacturing a wooden board according to the first aspect, in the step of manufacturing small wooden flakes, the wooden flakes are pulverized so as to split along the fiber direction. In this way, the wooden flakes can be smoothly split to easily form uniform small wooden flakes within the target size range, and the production of the small wooden flakes can be further facilitated.

A third invention is based on the method for manufacturing a wooden board according to the first or second invention, wherein at least one of the wooden flake manufacturing step and the wooden small flake manufacturing step includes: It is characterized by having a classification process for the purpose of sorting out the thickness. Specifically, only the wooden flake production process may include a classification step for the purpose of selecting wooden flakes having a size comparable to the small wooden flakes from among the wooden flakes obtained in the process. Only the small wooden flakes manufacturing process may include a classification process for the purpose of sorting out the sizes of the small wooden flakes obtained in the process so that the small wooden flakes obtained in the process are more uniform in size. , the wooden flake manufacturing process and the wooden small flake manufacturing process may include the above-described classification step. By doing so, small wooden flakes having a more uniform size can be obtained, so that the wooden board is made more uniform by gathering the flakes having a uniform size within a certain range. As a result, not only the strength of the wooden board but also the dimensional stability and surface properties can be improved.

A fourth invention is characterized in that, in the wood board manufacturing method of any one of the first to third inventions, the hot pressing step forms a wood board having a density of 500 to 800 kg/m ³ . do. This will further increase the strength of the wooden board.

As described above, according to the present invention, the small wooden flakes formed by the wooden flake manufacturing process and the wooden flake manufacturing process are further subjected to the adhesive application process, the mat forming process, and the heat pressing process, It is possible to easily manufacture a wooden board in which a large number of small wooden flakes having front and back surfaces along the fiber direction are laminated together and bonded together. In addition, due to the small wooden flakes manufacturing process, many small wooden flakes are uniform in size with little variation, and the strength of the wooden board can be increased. Dimensional stability and surface properties are obtained.

FIG. 1 is a cross-sectional view of a wooden board according to an embodiment of the present invention. FIG. 2 is an enlarged cross-sectional view of the main part of the wooden board. FIG. 3 is an enlarged perspective view schematically showing the wooden flakes. FIG. 4 is a diagram showing a manufacturing process of a wooden board. FIG. 5 is an enlarged cross-sectional view showing a state in which a wooden board is hot-pressed from a mat, which is an aggregate of small wooden flakes. FIG. 6 is a diagram showing the characteristics of wooden boards in comparison with boards of other materials.

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

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

The wooden board A, as enlarged in FIG. The wood flakes 1, 1, . . . have a narrow and constant range of thickness.

Regarding the small wooden flakes 1, as shown in an enlarged view in FIG. 0.10 to 0.30 mm (0.10 mm or more and 0.30 mm or less), more preferably 0.15 to 0.25 mm (0.15 mm or more and 0.25 mm or less), still more preferably 0.15 to 0.30 mm. 20 mm (0.15 mm or more and 0.20 mm or less). The characteristics of the wooden board A are determined by the flakes 1, 1, . . . of the thin thickness t. The thickness t of the wooden flakes 1 is an average value. In other words, the small wooden flakes 1 according to the present invention are strands (also referred to as cut pieces in the present invention) that are used as elements (constituent materials) of general OSBs and generally have a thickness of 0.6 to It is about 1.5 mm, but the thickness is thinner than that.

In addition, the small wood flakes 1 have fibers 1a, 1a, . It has an elongated shape (strip shape) longer than the dimension d2. When the fiber direction dimension d1 is the length and the fiber orthogonal direction dimension d2 is the width, the length d1 is 40 mm or less, preferably 35 mm or less, more preferably 30 mm or less, even more preferably 25 mm or less, still more preferably 10 to 20 mm ( 10 mm or more and 20 mm or less). Also, the width d2 is 40 mm or less, preferably 15 mm or less, more preferably 0.5 to 5 mm (0.5 mm or more and 5 mm or less). Both the length d1 and the width d2 of the wooden flakes 1 are average values. In other words, the small wooden flakes 1, 1, ... according to the present invention are cut pieces that are used as general OSB constituent materials, and generally have a length of 110 mm (about 150 to 250 mm if long). While the width is 15 to 25 mm (long ones are about 1/3 of the length), the flakes are smaller in size. Moreover, as will be described later, the small wood flakes 1 according to the present embodiment are wood flakes cut from raw wood (also referred to as wood flakes after cutting) as they are (also called wood flakes after cutting), which are then crushed and made smaller than the raw wood flakes (not shown). In order to define something different from the wood flakes after cutting, the wood flakes after cutting are referred to as "small wood flakes".

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

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

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

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

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

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

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

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

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

The cut wooden flakes obtained in step P1 are passed through a sieve or the like to sort (classify) the size of the cut wooden flakes (classification step). In some cases, woody flakes having a size comparable to the obtained woody flakes 1, 1, . . . In that case, the wooden flakes can be used in the adhesive application step P3 as the small wooden flakes 1, 1, . . . without being subjected to the small wooden flake manufacturing step P2.

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

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

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

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

The small wood flakes 1, 1, . . . obtained in the pulverization step are passed through a sieve or the like to sort out (classify) the size of the small wood flakes 1, 1, . As a result, the large number of small wooden flakes 1, 1, . . . are finer and uniform in size and shape. The small wooden flakes 1 are manufactured as described above.

Specific manufacturing conditions for the wooden flake manufacturing step P2 are described below.
(1) Using a hammer mill with a diameter of 320 mm, the cut wooden flakes were pulverized at 1125 rpm (about 1130 m/min) for several seconds (for example, about 1 to 3 seconds). After that, it was screened through a mesh of Φ20 mm, and those that passed through the mesh were designated as small wooden flakes 1, 1, . . . As a result, small wooden flakes 1, 1, . . . which were fine and uniformly uniform in size and shape were obtained.
(2) Using a hammer mill with a diameter of 540 mm, the cut wooden flakes were pulverized at 1500 rpm (about 2545 m/min) for several seconds (for example, about 1 to 3 seconds). After that, it was sorted through a mesh of Φ15 mm, and those that passed through the mesh were designated as small wooden flakes 1, 1, . . . As a result, small wooden flakes 1, 1, . . . were obtained which were slightly finer than the small wooden flakes 1, 1, .
(3) Using a hammer mill with a diameter of 200 mm, the cut wooden flakes were pulverized at 2000 rpm (1256 m/min) for several seconds (for example, about 1 to 3 seconds). After that, it was screened with a mesh of Φ10 mm to Φ20 mm, and those that passed through the mesh were designated as small wooden flakes 1, 1, . . . As a result, small wooden flakes 1, 1, .

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

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

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

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

In addition, since the small wooden flakes 1, 1, . Variation in the strength of the wooden board A is eliminated. In other words, in a strand board using large strands (cutting pieces), for example, an uneven mat including knots causes thin and low-strength portions partially (spots), resulting in variations in strength, but this is eliminated. Moreover, the thinner the wooden flakes 1, 1, . . . In general, a strand board using large strands (cutting pieces) can increase the strength. It combines the homogeneity and strength of Board A.

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

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

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

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

The root-mean-square height Sq is a parameter corresponding to the standard deviation of the distance from the average plane, and corresponds to the standard deviation of height. Therefore, the smaller the value of the root-mean-square height Sq on the surface of the wooden board A, the smaller the variation in the size of the irregularities on the surface, and the better the surface properties. Specifically, if the thickness t of the small wooden flakes 1, 1, . . . , and the thickness t of the wooden flakes 1, 1, . . . 008 μm or less, the surface roughness of which is comparable to that of MDF, which has excellent surface properties.

The arithmetic mean height Sa represents the mean of the absolute values of the height differences of each point with respect to the mean plane of the surface. Therefore, the smaller the value of the arithmetic mean height Sa on the surface of the wooden board A, the less large unevenness the surface has and the more excellent the surface properties. Specifically, if the thickness t of the wooden flakes 1, 1, . . . If the thickness t of the wooden flakes 1, 1, ... is 0.25 mm or less (preferably 0.20 mm or less), the arithmetic mean height Sa on the surface of the wooden board A is 0.002 μm or more and 0.005 μm or less. The surface roughness of the wooden board A is even better than that of MDF, which has excellent surface properties.

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

Therefore, the manufacturing method of the woody board A of the above-described embodiment and the woody board A obtained by the manufacturing method can have the following effects.

The method for manufacturing the wooden board A further includes the wooden small flake manufacturing step P2 after the wooden flake manufacturing step P1, so that the average value of the thickness t is 0.05 to 0.35 mm, and the fiber direction dimension d1 along the fiber direction To easily manufacture a large number of small wooden flakes 1, 1, ... having an average value of (length) of 40 mm or less and an average value of dimension d2 (width) perpendicular to the fiber direction of 40 mm or less. can be done.

In addition, since the manufacturing method of the wooden board A further includes the adhesive application step P3, the mat forming step P4, and the heat pressing step P5 after the small wooden flake manufacturing step P2, a large number of small wooden flakes 1 and 1 of uniform size can be obtained. 1, . . . are laminated in an aggregated state, and the wooden board A composed of a single layer by adhesion and integration can be easily manufactured.

The single-layer wooden board A formed by the above steps P1 to P5 is composed only of the small wooden flakes 1, 1, . Since the value is within the narrow range of 0.05 to 0.35 mm, the thickness t of the large number of small wooden flakes 1, 1, . . . In addition, since the average value of the fiber direction dimension d1 (length) and the fiber orthogonal direction dimension d2 (width) of the wooden flakes 1, 1, . . . Aligned small wooden flakes 1, 1, . . . Therefore, not only does the strength of the wood board A increase, warping due to moisture absorption and desorption is less likely to occur, and good dimensional stability comparable to that of plywood made of plywood from the South Seas can be obtained. In addition, since a large number of small wooden flakes 1, 1, . It becomes a thing.

In particular, the average value of the thickness t of the small wooden flakes 1, 1, ... in the wooden board A is 0.15 to 0.25 mm, the average value of the fiber direction dimension d1 is 20 mm or less, and the average value of the fiber orthogonal direction dimension d2 is 5 mm or less, the dimensional stability and surface properties of the wooden board A are further improved.

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

<Other embodiments>
In the above embodiment, the wood board A is composed of small wood flakes 1 obtained by crushing wood flakes cut from raw wood (wood flakes after cutting) to make them smaller. A wooden board can also be composed of wooden flakes cut from raw wood (wood flakes after cutting).

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

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

A Wooden board A1 Mat P1 Wooden flake manufacturing process P2 Small wooden flake manufacturing process P3 Adhesive application process P4 Mat forming process P5 Heat pressing process 1 Small wooden flake 1a Fiber t Thickness d1 Fiber direction dimension (length)
d2 Fiber orthogonal direction dimension (width)

TECHNICAL FIELD The present invention relates to a method for manufacturing a wooden board.

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

Plywood made from domestic coniferous trees poses no problem in terms of raw material depletion, but its surface properties are insufficient, so it is limited to applications that require special strength.

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

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

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

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

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

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

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

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

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

The present invention has been made in view of these points, and its object is to improve the wooden board structure in which a large number of wooden flakes are laminated, so that the wood flakes can be used only in a narrow and constant range of size. To obtain a wooden board which has high strength, is excellent in dimensional stability and surface properties, and is easy to manufacture.

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

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

Specifically, the first invention is directed to a method for manufacturing a wooden board in which a large number of elongated small wooden flakes having front and back surfaces along the fiber direction are laminated together and bonded together. be. This manufacturing method comprises a wooden flake manufacturing process for cutting raw wood to produce wooden flakes, a small wooden flake manufacturing process for pulverizing the wooden flakes to form small wooden flakes smaller than the wooden flakes, and bonding to the small wooden flakes. an adhesive application step of applying an adhesive; a mat forming step of forming a mat of the small wood flakes by laminating a large number of small wood flakes coated with the adhesive while gathering them in the thickness direction; in the step of producing small wooden flakes by pulverizing the wooden flakes so as to split them along the fiber direction, thereby It is characterized by producing elongated small wooden flakes in which the dimension in the direction orthogonal to the fiber along the direction of the fiber is shorter than that of the wooden flakes .

In the first aspect of the present invention, in the step of producing wooden flakes, raw wood is cut to produce wooden flakes that are thinner and smaller than the cut pieces normally used as OSB constituent materials. The wooden flakes are pulverized so as to split along the fiber direction . In this way, the woody flakes are smoothly split to form elongated small woody flakes smaller than the woody flakes, more specifically, shorter in the dimension perpendicular to the fiber than the woody flakes . In this way, through the two-step process , homogeneous small wooden flakes having a target size range are produced, so that the small wooden flakes can be easily produced.

Further, in the adhesive application step, adhesive was applied to the small wood flakes formed in the above step, and then in the mat forming step, a large number of small wood flakes coated with the adhesive were assembled in the thickness direction. A mat of the small wood flakes is formed by laminating the wood flakes in a state, and finally, the mat is compressed and integrated by a hot-pressing process, so that a large number of small wood flakes are laminated in an aggregated state and integrated by adhesion. A wooden board is molded. Since the wooden board is manufactured through the three-step process after the two-step process of forming the small wooden flakes, the wooden board can be easily manufactured.

The wood board obtained in this way is made by crushing wood flakes having a specific thickness obtained in the wood flake manufacturing process in the fiber direction of the wood flakes in the wood flake manufacturing process. The thickness of the small wooden flakes is extremely thin, and a large number of small wooden flakes have a uniform thickness with little variation in thickness. In addition, since the length and width of the small wooden flakes are also within a certain range, the wooden board is made homogeneous by gathering the small wooden flakes of uniform size within a certain range. As a result, local defects and variations in density are greatly reduced, making it possible to stably develop the strength of the wooden board. In addition, warping due to moisture absorption and desorption is less likely to occur, and good dimensional stability comparable to that of plywood made of South Sea wood can be obtained. In addition, since a large number of small wooden flakes are uniform in size, the surface of the wooden board does not have large irregularities unlike ordinary OSB, and the wooden board has excellent surface properties. In addition, since a large number of small wooden flakes of uniform size are collected and laminated, the production thereof is facilitated .

A second invention is based on the method for manufacturing a wooden board according to the first invention, wherein at least one of the wooden flake manufacturing step and the wooden small flake manufacturing step comprises selecting the size of the obtained wooden flakes or small wooden flakes. It is characterized by having a classification step for the purpose of Specifically, only the wooden flake production process may include a classification step for the purpose of selecting wooden flakes having a size comparable to the small wooden flakes from among the wooden flakes obtained in the process. Only the small wooden flakes manufacturing process may include a classification process for the purpose of sorting out the sizes of the small wooden flakes obtained in the process so that the small wooden flakes obtained in the process are more uniform in size. , the wooden flake manufacturing process and the wooden small flake manufacturing process may include the above-described classification step. By doing so, small wooden flakes having a more uniform size can be obtained, so that the wooden board is made more uniform by gathering the flakes having a uniform size within a certain range. As a result, not only the strength of the wooden board but also the dimensional stability and surface properties can be improved.

A third aspect of the invention is characterized in that, in the method of manufacturing a wooden board according to the first or second aspect, the hot pressing step forms a wooden board having a density of 500 to 800 kg/m ³ . This will further increase the strength of the wooden board.

As described above, according to the present invention, the small wooden flakes formed by the wooden flake manufacturing process and the wooden flake manufacturing process are further subjected to the adhesive application process, the mat forming process, and the heat pressing process, It is possible to easily manufacture a wooden board in which a large number of small wooden flakes having front and back surfaces along the fiber direction are laminated together and bonded together. In addition, due to the small wooden flakes manufacturing process, many small wooden flakes are uniform in size with little variation, and the strength of the wooden board can be increased. Dimensional stability and surface properties are obtained.

FIG. 1 is a cross-sectional view of a wooden board according to an embodiment of the present invention. FIG. 2 is an enlarged cross-sectional view of the main part of the wooden board. FIG. 3 is an enlarged perspective view schematically showing the wooden flakes. FIG. 4 is a diagram showing a manufacturing process of a wooden board. FIG. 5 is an enlarged cross-sectional view showing a state in which a wooden board is hot-pressed from a mat, which is an aggregate of small wooden flakes. FIG. 6 is a diagram showing the characteristics of wooden boards in comparison with boards of other materials.

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

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

The wooden board A, as enlarged in FIG. The wood flakes 1, 1, . . . have a narrow and constant range of thickness.

Regarding the small wooden flakes 1, as shown in an enlarged view in FIG. 0.10 to 0.30 mm (0.10 mm or more and 0.30 mm or less), more preferably 0.15 to 0.25 mm (0.15 mm or more and 0.25 mm or less), still more preferably 0.15 to 0.30 mm. 20 mm (0.15 mm or more and 0.20 mm or less). The characteristics of the wooden board A are determined by the flakes 1, 1, . . . of the thin thickness t. The thickness t of the wooden flakes 1 is an average value. In other words, the small wooden flakes 1 according to the present invention are strands (also referred to as cut pieces in the present invention) that are used as elements (constituent materials) of general OSBs and generally have a thickness of 0.6 to It is about 1.5 mm, but the thickness is thinner than that.

In addition, the small wood flakes 1 have fibers 1a, 1a, . It has an elongated shape (strip shape) longer than the dimension d2. When the fiber direction dimension d1 is the length and the fiber orthogonal direction dimension d2 is the width, the length d1 is 40 mm or less, preferably 35 mm or less, more preferably 30 mm or less, even more preferably 25 mm or less, still more preferably 10 to 20 mm ( 10 mm or more and 20 mm or less). Also, the width d2 is 40 mm or less, preferably 15 mm or less, more preferably 0.5 to 5 mm (0.5 mm or more and 5 mm or less). Both the length d1 and the width d2 of the wooden flakes 1 are average values. In other words, the small wooden flakes 1, 1, ... according to the present invention are cut pieces that are used as general OSB constituent materials, and generally have a length of 110 mm (about 150 to 250 mm if long). While the width is 15 to 25 mm (long ones are about 1/3 of the length), the flakes are smaller in size. Moreover, as will be described later, the small wood flakes 1 according to the present embodiment are wood flakes cut from raw wood (also referred to as wood flakes after cutting) as they are (also called wood flakes after cutting), which are then crushed and made smaller than the raw wood flakes (not shown). In order to define something different from the wood flakes after cutting, the wood flakes after cutting are referred to as "small wood flakes".

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

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

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

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

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

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

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

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

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

The cut wooden flakes obtained in step P1 are passed through a sieve or the like to sort (classify) the size of the cut wooden flakes (classification step). In some cases, woody flakes having a size comparable to the obtained woody flakes 1, 1, . . . In that case, the wooden flakes can be used in the adhesive application step P3 as the small wooden flakes 1, 1, . . . without being subjected to the small wooden flake manufacturing step P2.

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

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

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

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

The small wood flakes 1, 1, . . . obtained in the pulverization step are passed through a sieve or the like to sort out (classify) the size of the small wood flakes 1, 1, . As a result, the large number of small wooden flakes 1, 1, . . . are finer and uniform in size and shape. The small wooden flakes 1 are manufactured as described above.

Specific manufacturing conditions for the wooden flake manufacturing step P2 are described below.
(1) Using a hammer mill with a diameter of 320 mm, the cut wooden flakes were pulverized at 1125 rpm (about 1130 m/min) for several seconds (for example, about 1 to 3 seconds). After that, it was screened through a mesh of Φ20 mm, and those that passed through the mesh were designated as small wooden flakes 1, 1, . . . As a result, small wooden flakes 1, 1, . . . which were fine and uniformly uniform in size and shape were obtained.
(2) Using a hammer mill with a diameter of 540 mm, the cut wooden flakes were pulverized at 1500 rpm (about 2545 m/min) for several seconds (for example, about 1 to 3 seconds). After that, it was sorted through a mesh of Φ15 mm, and those that passed through the mesh were designated as small wooden flakes 1, 1, . . . As a result, small wooden flakes 1, 1, . . . were obtained which were slightly finer than the small wooden flakes 1, 1, .
(3) Using a hammer mill with a diameter of 200 mm, the cut wooden flakes were pulverized at 2000 rpm (1256 m/min) for several seconds (for example, about 1 to 3 seconds). After that, it was screened with a mesh of Φ10 mm to Φ20 mm, and those that passed through the mesh were designated as small wooden flakes 1, 1, . . . As a result, small wooden flakes 1, 1, .

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

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

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

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

In addition, since the small wooden flakes 1, 1, . Variation in the strength of the wooden board A is eliminated. In other words, in a strand board using large strands (cutting pieces), for example, an uneven mat including knots causes thin and low-strength portions partially (spots), resulting in variations in strength, but this is eliminated. Moreover, the thinner the wooden flakes 1, 1, . . . In general, a strand board using large strands (cutting pieces) can increase the strength. It combines the homogeneity and strength of Board A.

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

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

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

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

The root-mean-square height Sq is a parameter corresponding to the standard deviation of the distance from the average plane, and corresponds to the standard deviation of height. Therefore, the smaller the value of the root-mean-square height Sq on the surface of the wooden board A, the smaller the variation in the size of the irregularities on the surface, and the better the surface properties. Specifically, if the thickness t of the small wooden flakes 1, 1, . . . , and the thickness t of the wooden flakes 1, 1, . . . 008 μm or less, the surface roughness of which is comparable to that of MDF, which has excellent surface properties.

The arithmetic mean height Sa represents the mean of the absolute values of the height differences of each point with respect to the mean plane of the surface. Therefore, the smaller the value of the arithmetic mean height Sa on the surface of the wooden board A, the less large unevenness the surface has and the more excellent the surface properties. Specifically, if the thickness t of the wooden flakes 1, 1, . . . If the thickness t of the wooden flakes 1, 1, ... is 0.25 mm or less (preferably 0.20 mm or less), the arithmetic mean height Sa on the surface of the wooden board A is 0.002 μm or more and 0.005 μm or less. The surface roughness of the wooden board A is even better than that of MDF, which has excellent surface properties.

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

Therefore, the manufacturing method of the woody board A of the above-described embodiment and the woody board A obtained by the manufacturing method can have the following effects.

The method for manufacturing the wooden board A further includes the wooden small flake manufacturing step P2 after the wooden flake manufacturing step P1, so that the average value of the thickness t is 0.05 to 0.35 mm, and the fiber direction dimension d1 along the fiber direction To easily manufacture a large number of small wooden flakes 1, 1, ... having an average value of (length) of 40 mm or less and an average value of dimension d2 (width) perpendicular to the fiber direction of 40 mm or less. can be done.

In addition, since the manufacturing method of the wooden board A further includes the adhesive application step P3, the mat forming step P4, and the heat pressing step P5 after the small wooden flake manufacturing step P2, a large number of small wooden flakes 1 and 1 of uniform size can be obtained. 1, . . . are laminated in an aggregated state, and the wooden board A composed of a single layer by adhesion and integration can be easily manufactured.

The single-layer wooden board A formed by the above steps P1 to P5 is composed only of the small wooden flakes 1, 1, . Since the value is within the narrow range of 0.05 to 0.35 mm, the thickness t of the large number of small wooden flakes 1, 1, . . . In addition, since the average value of the fiber direction dimension d1 (length) and the fiber orthogonal direction dimension d2 (width) of the wooden flakes 1, 1, . . . Aligned small wooden flakes 1, 1, . . . Therefore, not only does the strength of the wood board A increase, warping due to moisture absorption and desorption is less likely to occur, and good dimensional stability comparable to that of plywood made of plywood from the South Seas can be obtained. In addition, since a large number of small wooden flakes 1, 1, . It becomes a thing.

In particular, the average value of the thickness t of the small wooden flakes 1, 1, ... in the wooden board A is 0.15 to 0.25 mm, the average value of the fiber direction dimension d1 is 20 mm or less, and the average value of the fiber orthogonal direction dimension d2 is 5 mm or less, the dimensional stability and surface properties of the wooden board A are further improved.

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

<Other embodiments>
In the above embodiment, the wood board A is composed of small wood flakes 1 obtained by crushing wood flakes cut from raw wood (wood flakes after cutting) to make them smaller. A wooden board can also be composed of wooden flakes cut from raw wood (wood flakes after cutting).

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

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

A Wooden board A1 Mat P1 Wooden flake manufacturing process P2 Small wooden flake manufacturing process P3 Adhesive application process P4 Mat forming process P5 Heat pressing process 1 Small wooden flake 1a Fiber t Thickness d1 Fiber direction dimension (length)
d2 Fiber orthogonal direction dimension (width)

Claims (4)

A method for manufacturing a wooden board in which a large number of small wooden flakes having front and back surfaces along the fiber direction are laminated together and bonded together,
A wooden flake manufacturing process in which raw wood is cut to make wooden flakes,
a small wooden flake manufacturing step of pulverizing the wooden flakes to form small wooden flakes smaller than the wooden flakes;
an adhesive application step of applying an adhesive to the wooden flakes;
a mat forming step of forming a mat of the small wood flakes by laminating a large number of the small wood flakes coated with the adhesive in a state of being aggregated in the thickness direction;
A method for producing a wooden board, comprising: a hot-pressing step of compressing and integrating the mat by hot-pressing. In the method for manufacturing a wooden board according to claim 1,
A method for producing a wooden board, wherein in the step of producing small wooden flakes, the wooden flakes are pulverized so as to split along the fiber direction. In the method for manufacturing a wooden board according to claim 1 or 2,
At least one of the wooden flake manufacturing process and the wooden small flake manufacturing process has a classification step for the purpose of selecting the size of the obtained wooden flakes or small wooden flakes. Production method. In the method for manufacturing a wooden board according to any one of claims 1 to 3,
A method for producing a wooden board, wherein the hot pressing step forms a wooden board having a density of 500 to 800 kg/m ³ .

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