Wood board

Abstract

To provide a woody board capable of enhancing the degree of freedom of the selection of a raw material while enhancing strength while achieving wt. reduction.SOLUTION: The woody board 1 includes slender woody small pieces 2 having a thickness of ≤ 0. 5mm and a length along a fiber direction of ≥ 20mm, and woody small pieces 3 having a length smaller than that of the slender woody small pieces, and is bonded and integrated.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to wood boards. [Background technology]

[0002] From the viewpoint of protecting forests and wood resources, particle boards, which are made by bonding together small pieces of wood with a binder, have been widely used as furniture and building materials. To improve the strength of such particle boards, it is necessary to increase the density and thickness, which tends to increase the mass. For example, Patent Document 1 below discloses a wooden board made by laminating and bonding together a large number of small, elongated wooden flakes. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 7064552 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the wood board described in Patent Document 1 above is made up of a large number of small, elongated wood flakes with little variation in thickness, length, and width within a certain range in order to increase strength, which has the problem of limiting the freedom of raw material selection.

[0005] The present disclosure has been made in consideration of the above-mentioned circumstances, and aims to provide a wood board that is lightweight, has improved strength, and allows for greater freedom in raw material selection. [Means for solving the problem]

[0006] In order to achieve the above-mentioned objective, the wood board of the present disclosure is characterized by including elongated wood pieces having a thickness of 0.5 mm or less and a length along the fiber direction of 20 mm or more, and wood pieces shorter than the elongated wood pieces, which are glued together. [Effects of the Invention]

[0007] The wood board according to the present disclosure has the above-described configuration, which allows for greater freedom in the selection of raw materials while also improving strength and reducing weight. [Brief explanation of the drawings]

[0008] [Figure 1] (a) is a schematic cross-sectional view showing an example of a wood board according to one embodiment of the present disclosure; (b) is a schematic plan view showing an example of an elongated wood piece included in the wood board; (c) is a schematic plan view showing an example of a wood piece included in the wood board; and (d) is a schematic plan view showing another example of the same wood piece. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. FIG. 1 is a diagram showing an example of a wood board according to this embodiment, and an example of the thin wood pieces and wood pieces included therein.

[0010] As shown in FIG. 1( a), the wood board 1 according to this embodiment includes thin wood pieces 2 (2) each having a thickness of 0.5 mm or less and a length in the fiber direction of 20 mm or more, and thin wood pieces 3 (3) shorter than the thin wood pieces 2, which are bonded together. This configuration allows the thin wood pieces 2 to connect the thin wood pieces 3, resulting in improved strength while still reducing weight compared to a typical particle board made of only thin wood pieces bonded together. In other words, even if the strength is comparable to that of a typical particle board, the board can be made thinner and lighter, resulting in a lower density. Furthermore, compared to a configuration made of only thin wood pieces 2 (2) with little shape variation, the inclusion of thin wood pieces 3, which are similar to those used in typical particle boards, allows for greater flexibility in raw material selection, which is expected to improve raw material procurement.

[0011] The wooden board 1 may be used as various interior building materials such as flooring, walling, ceilings, fittings, and undercoatings for these, as well as furniture. The shape and size of the wooden board 1 may be appropriate depending on the intended use of the wooden board 1. For example, the wooden board 1 may be rectangular in plan view (seen in the thickness direction). In this case, the wooden board 1 may be square in plan view or rectangular in shape with its length extended in a first direction. The dimensions of the wooden board 1 along the first direction (length) and along the second direction (width) may vary depending on the intended use of the wooden board 1, and may be, for example, approximately 600 mm to 2000 mm in length and approximately 100 mm to 400 mm in width. The thickness of the wooden board 1 may vary depending on the intended use of the wooden board 1, and may be, for example, approximately 2 mm to 20 mm, or approximately 3 mm to 15 mm. The specific gravity of the wooden board 1 may be, for example, 0.4 or more and 0.8 or less, although it depends on the use of the wooden board 1 and the like. Appropriate chamfered portions may be provided on the four peripheral edges on at least one of both sides in the thickness direction of the wood board 1. Appropriate solid portions may be provided on one or both of both ends in the first direction and both ends in the second direction of the wood board 1.

[0012] The elongated thin wood pieces 2 included in this wood board 1 may have a width of 10 mm or less. With this configuration, the aspect ratio defined by "length of the elongated thin wood pieces 2" / "width of the elongated thin wood pieces 2" is 2 or more, and the elongated thin wood pieces 2 have an elongated shape as shown in Figure 1(b), so the elongated thin wood pieces 2 can more effectively improve the strength of the wood board 1. The elongated thin wood pieces 2 may have an aspect ratio of 2 to 40, or 4 to 25. The thin wood pieces 2 may have a thickness of 0.2 mm or more, a width of 1 mm or more, and a length of 50 mm or less. With this configuration, the thin wood pieces 2 are less likely to be crushed or tangled when mixed with the small wood pieces 3, compared to a configuration including thin wood pieces that are too small in thickness or width or too large in length. That is, the elongated wood pieces 2 may have a thickness of 0.2 mm to 0.5 mm, a width of 1 mm to 10 mm, and a length of 20 mm to 50 mm.

[0013] The dimensions (thickness, width, and length) of the elongated wood pieces 2 may all be within the above-mentioned ranges for the numerous elongated wood pieces 2 contained in the wood board 1, or the average values ​​may be within the ranges, including those outside the ranges. In this case, a predetermined number (e.g., approximately 20 to 100) of elongated wood pieces 2 may be randomly selected from the numerous elongated wood pieces 2 used as raw material to form the wood board 1 to reduce bias, and the dimensions (thickness, width, and length) of each of the selected elongated wood pieces 2 may be measured and the average values ​​calculated. The width and length of each elongated wood piece 2 may be measured on an image using, for example, a digital microscope. The thickness of each elongated wood piece 2 may be measured using, for example, a digital thickness gauge. The dimensions (thickness, width, and length) of the elongated wood pieces 2 are not limited to the average values ​​of a predetermined number of sample pieces as described above, but may also be target dimension values ​​when manufacturing a large number of elongated wood pieces 2 using a manufacturing method that results in relatively small variation in each dimension, as described below.

[0014] The raw wood (tree species) used for the long and thin wood pieces 2 may be various coniferous trees such as cedar, cypress, larch, red pine, Sakhalin fir, and radiata pine, or broadleaf trees such as beech, oak, white birch, acacia, birch, poplar, and lauan, or may be bamboo or other tree species. The tree species used for the long and thin wood pieces 2 contained in the wood board 1 may be one species or multiple species. The specific gravity of the long and thin wood pieces 2 may be about 0.3 to 0.8, or may be 0.6 or more. The moisture content of the long and thin wood pieces 2 may be about 2% to 25%, or preferably 15% or less. The length direction of the elongated wood piece 2 is along the fiber direction, which means that since it is natural wood, it is sufficient that it is generally along the fiber direction, and it is also possible that the fiber direction is partially along the width direction or diagonal direction due to knots, etc.

[0015] The elongated wood pieces 2 having the above-described structure may be manufactured, for example, as follows. A thin board with a relatively specific thickness (e.g., 0.2 mm), such as a sliced ​​veneer (veneer) formed by thinly slicing various natural wood materials or a rotary veneer formed using a rotary lathe, is cut parallel to the grain direction into multiple flat string-like pieces with a specific width (e.g., 2 mm) using an appropriate cutter. The thin board may be cut into multiple pieces using multiple cutters arranged at equal intervals (predetermined widths (e.g., 2 mm)) in the width direction (perpendicular to the grain). These multiple flat string-like pieces may then be cut to a specific length (e.g., 45 mm) to produce the elongated wood strips 2. Alternatively, the thin board may be cut perpendicular to the grain direction using an appropriate cutter to a specific length (e.g., 45 mm) corresponding to the length of the elongated wood strips 2, and then cut to a specific width (e.g., 2 mm) to produce the elongated wood strips 2. With this configuration, the variations in the dimensions of the many manufactured elongated wood pieces 2 can be made relatively small.

[0016] Alternatively, wood wool of a predetermined thickness and width may be produced using a wood wool production device, and then cut to a predetermined length to produce the thin wood pieces 2. Alternatively, square lumber of a size corresponding to the predetermined length of the thin wood pieces 2 may be cut to a predetermined thickness and width using a wood wool production device to produce the thin wood pieces 2. With these configurations, similar to the above, the variation in the dimensions of the many thin wood pieces 2 produced can be made relatively small. Alternatively, the thin boards described above may be cut perpendicular to the fiber direction using an appropriate cutter to a predetermined dimension corresponding to the length of the elongated wood pieces 2, and then crushed to a predetermined width using an appropriate crusher such as a cutter mill or hammer mill to produce the elongated wood pieces 2. In this case, if an impact crusher is used, the wood pieces are more likely to split along the fiber, making it easier to crush in the width direction. In this case, the width of the elongated wood pieces 2 is more likely to vary than the thickness and length, but the wood pieces may be sorted using an appropriate sieve or classifier to reduce variation.

[0017] The raw wood material used to produce the elongated thin wood pieces 2 may be logs, sawn lumber processed into an appropriate shape, chips, or demolition materials. The raw wood material used to produce the elongated thin wood pieces 2 may be made wet by immersing it in water, impregnating it with water under reduced pressure, or steaming it, and then processed into the elongated thin wood pieces 2 in that state and dried. Alternatively, the wet raw wood material may be processed into an appropriate shape, dried, and then crushed or cut to produce the elongated thin wood pieces 2. The method for manufacturing the elongated wood pieces 2 is not limited to the above-described method, but may also be produced using a strander that produces strands (pieces) or a flaker that produces chips, or may be produced in various other ways.

[0018] The wood pieces 3 included in the wood board 1 have an average length that is shorter than the length of the elongated wood pieces 2. The wood pieces 3 may also have an average thickness that is greater than the thickness of the elongated wood pieces 2. The wood pieces 3 may have a thickness of 0.6 mm or more and a length of 15 mm or less. This configuration makes it easier to arrange the elongated wood pieces 2 so that they connect the wood pieces 3 that are thicker and shorter than the elongated wood pieces 2, thereby effectively improving the strength of the wood board 1. Furthermore, because the length is about the same as the wood pieces that make up general particle boards obtained by crushing and shredding waste materials such as building demolition materials and thinning materials, raw material procurement can be improved. The wood pieces 3 may have a thickness of 3 mm or less, a length of 2 mm or more, and a width of 0.6 mm to 15 mm or less. In other words, the wood pieces 3 may have a thickness of 0.6 mm to 3 mm, a length of 2 mm to 15 mm, and a width of 0.6 mm to 15 mm.

[0019] As described above, each dimension (thickness, width, and length) of the wood pieces 3 may be within the above-mentioned range for all of the many wood pieces 3 included in the wood board 1, or the average value may be within the range for each dimension, including those outside the range. In this case, each dimension (thickness, width, and length) of the wood pieces 3 may be the average value obtained by measuring the dimensions of a predetermined number of sample pieces taken from the many wood pieces 3 used as raw material to form the wood board 1 in the same manner as described above. Furthermore, each dimension (thickness, width, and length) of the wood pieces 3 is not limited to the average value of such a predetermined number of sample pieces, but may also be a target dimension value when manufacturing a large number of wood pieces 3 using a manufacturing method that results in relatively small variation in each dimension.

[0020] 1(c) shows an example of granular wood pieces 3 with relatively small variations in dimensions (thickness, width, and length) and shape. Such wood pieces 3 may be manufactured by a manufacturing method similar to that of the above-described elongated wood pieces 2, or may be manufactured by other manufacturing methods. The wood chips contained in the wood board 1 are not limited to such granular wood chips 3, but may also be flake-like wood chips 4, which have relatively large variations in dimensions (thickness, width, and length) and shape, as shown in Figure 1(d). Such wood chips 4 may be obtained by crushing or pulverizing demolition materials used in general particle boards. The raw wood used for such wood pieces 3, 4 (hereinafter collectively referred to as wood pieces 3) may be various tree species similar to those described above, and may not be limited to one species but may be multiple species, and may also be waste wood such as demolished building materials or thinning materials. The specific gravity of the wood pieces 3 may be about 0.3 to 0.7, which may be lower than that of the above-mentioned elongated wood pieces 2. Furthermore, the moisture content of the wood pieces 3 may be about 2% to 25%, as above, and preferably 15% or less.

[0021] The mass ratio of the elongated wood pieces 2 to the wood pieces 3 contained in the wood board 1 may be 5:95 to 95:5. That is, the elongated wood pieces 2 may be contained in a proportion of 5 to 95 mass% of the wood material contained in the wood board 1 (100 mass%), with the wood pieces 3 being contained in the remainder. Preferably, the mass ratio of the elongated wood pieces 2 to the wood pieces 3 may be 5:95 to 50:50. That is, the elongated wood pieces 2 may be contained in a proportion of 5 to 50 mass% of the wood material contained in the wood board 1 (100 mass%). This configuration ensures strength compared to a configuration in which the proportion of the elongated wood pieces 2 to the total wood material contained in the wood board 1 is too small, and also provides greater freedom in raw material selection compared to a configuration in which the proportion of the elongated wood pieces 2 is too large. In other words, the wood chips 3 account for half or more of the mass of the entire wood material contained in the wood board 1, which allows for greater freedom in the selection of raw materials.

[0022] The adhesive used to bond the small wood strips 2 and 3 may be a thermosetting resin adhesive similar to that used in the manufacture of general particle boards, such as an isocyanate adhesive, a phenol resin, or a urea-melamine resin. Such an adhesive may be applied by spraying or the like after mixing the small wood strips 2 and 3, or may be applied by spraying or the like while mixing the small wood strips 2 and 3. Alternatively, the adhesive may be applied to each of the small wood strips 2 and 3 and then mixed. The amount of adhesive supplied (amount applied) may be approximately 5% to 15% by mass of the mass of the wood board 1.

[0023] The wood board 1 may be manufactured by a method similar to that used for manufacturing a general particle board. For example, the thin wood pieces 2 and 3 coated with adhesive as described above may be stacked in a mat shape, and the mat-like assembly may be formed into a predetermined thickness by a hot platen press, and then cut into appropriate widths and lengths to manufacture the wood board 1. When stacking in a mat shape, the thin wood pieces 2 and the thin wood pieces 3 may be mixed and stacked to achieve the above-mentioned mass ratio, or the thin wood pieces 2 and the thin wood pieces 3 may be alternately stacked in multiple layers to achieve the above-mentioned mass ratio. In this case, an appropriate mat thickness may be set so that the wood board 1 has a target specific gravity. For example, the mat thickness may be set to about 5 to 15 times the target thickness of the wood board 1. Furthermore, to improve the smoothness of both thickness-wise sides of the wood board 1, layers of fine wood pieces 3 or wood micro-pieces smaller than the thin wood pieces 3 may be provided on both thickness-wise sides of the mat-like aggregate. In other words, layers not containing the thin wood pieces 2 may be provided on both thickness-wise layers of the wood board 1. In this case, the mass of the wood micro-pieces may be included in the mass of the wood pieces 3. In other words, the mat-like aggregate may be formed so that the mass of the small wood pieces 3, including the mass of the minute wood pieces, and the mass of the small elongated wood pieces 2 have the above-mentioned mass ratio.

[0024] The pressing temperature when hot-pressing the mat-like assembly formed as described above may be approximately 160°C to 220°C. The pressing pressure when hot-pressing may be 1.5 MPa or more and 5 MPa or less, depending on the target density of the wood board 1, etc. The pressing time when hot-pressing may be set appropriately depending on the target thickness of the wood board 1, and may be approximately 10 to 20 seconds, or even approximately 15 seconds, for a target thickness of 1 mm of the wood board 1. In other words, if the target thickness of the wood board 1 is 10 mm, the pressing time may be approximately 100 to 200 seconds, or even approximately 150 seconds. The board formed by hot pressing as described above may be cooled and cured to an appropriate moisture content. The cured board may then be adjusted to the appropriate size, and at least one of the two thickness-wise sides may be polished or otherwise surface-finished to produce the wood board 1. If necessary, at least one of the thickness-wise sides of the wood board 1 may be painted or a decorative sheet such as a decorative veneer or resin film may be attached. The manufacturing method of the wood board 1 described above is merely an example, and various other modifications are possible. The wood board 1 according to this embodiment is not limited to the above-described configuration or the configurations of the examples described below, and may be configured in other configurations.

[0025] Next, an example of an embodiment of a wood board according to the present disclosure and a comparative example will be described with reference to Table 1. In the following Examples 1 to 5 and Comparative Examples 1 and 2, the dimensions of the wood pieces are the average values ​​of a predetermined number (40 pieces) of sample pieces, and the dimensions of the thin wood pieces are the target dimensional values ​​when manufactured using the manufacturing method described above that minimizes the variability of each dimension. In each of Examples 1 to 5 and Comparative Examples 1 and 2, wooden boards were used that were manufactured to have a total thickness of 12 mm and a specific gravity of 0.6. In each of Examples 1 to 5 and Comparative Examples 1 and 2, the adhesive used when molding the wooden boards was MDI (diphenylmethane diisocyanate), and the amount of application was 6 mass %. In Examples 1 and 2 and Comparative Example 1, small granular pieces of cedar measuring 9.9 mm in length, 6.3 mm in width, and 2.1 mm in thickness were used as the small wood pieces. In Examples 3 to 5 and Comparative Example 2, small granular pieces of Japanese cypress measuring 9.2 mm in length, 6.4 mm in width, and 1.4 mm in thickness were used as the small wood pieces. In Examples 1 to 5, the long and thin wood pieces used were beach pieces measuring 45 mm in length, 2 mm in width, and 0.2 mm in thickness.

[0026] In Example 1, the mass ratio of the cedar chips (wood chips) to the beech chips (long, thin wood chips) was 90:10. In Example 2, the mass ratio of cedar chips (wood chips) to beech chips (long, thin wood chips) was 80:20. In Example 3, the mass ratio of the cypress pieces (wood pieces) to the beech pieces (long, thin wood pieces) was 95:5. In Example 4, the mass ratio of the cypress pieces (wood pieces) to the beech pieces (long, thin wood pieces) was 90:10. In Example 5, the mass ratio of the cypress pieces (wood pieces) to the beech pieces (long, thin wood pieces) was 80:20. In Comparative Example 1, only cedar pieces (wood pieces) were used without including beach pieces (long, thin wood pieces), and in Comparative Example 2, only cypress pieces (wood pieces) were used without including beach pieces (long, thin wood pieces).

[0027] The test specimens of the wooden boards of Examples 1 to 5 and Comparative Examples 1 and 2 having the above-described configuration were subjected to the following evaluation tests in accordance with JIS A5908. <Bending strength test> In Example 1, the pressure was 19 MPa, in Example 2, 22 MPa, in Example 3, 14 MPa, in Example 4, 16 MPa, in Example 5, 17 MPa, in Comparative Example 1, 16 MPa, and in Comparative Example 2, 14 MPa. <Peel strength test> In Example 1, the pressure was 1.17 MPa, in Example 2, 0.93 MPa, in Example 3, 1.05 MPa, in Example 4, 0.87 MPa, in Example 5, 0.68 MPa, in Comparative Example 1, 0.88 MPa, and in Comparative Example 2, 0.98 MPa. <Water absorption thickness expansion rate test> In Example 1, it was 5.1%, in Example 2, 4.4%, in Example 3, 4.1%, in Example 4, 4.6%, in Example 5, 4.7%, in Comparative Example 1, 5.6%, and in Comparative Example 2, 4.2%. [Table 1] From the above results, Examples 1 and 2, which contained small beech pieces (small, thin wood pieces), showed better results in bending strength, peel strength, and water absorption thickness swelling rate than Comparative Example 1, which contained only small cedar pieces (small wood pieces). Example 3, which contained small beech pieces (small, thin wood pieces), showed better results in both peel strength and water absorption thickness swelling rate than Comparative Example 2, which contained only small cypress pieces (small wood pieces). Examples 4 and 5, which contained small beech pieces (small, thin wood pieces), showed better bending strength than Comparative Example 2, which contained only small cypress pieces (small wood pieces).

[0028] <Additional Notes> The above description of the embodiments discloses the following techniques. <Technology 1> The wooden board includes thin wooden pieces each having a thickness of 0.5 mm or less and a length of 20 mm or more along the fiber direction, and thin wooden pieces each having a length smaller than the thin wooden pieces, which are bonded together. <Technology 2> The wood board according to claim 1, wherein the elongated wood pieces have a width of 10 mm or less. <Technology 3> The wood board according to Technology 1 or Technology 2, wherein the elongated wood pieces have a thickness of 0.2 mm or more, a width of 1 mm or more, and a length of 50 mm or less. <Technology 4> The wood board according to any one of Techniques 1 to 3, wherein the mass ratio of the elongated wood pieces to the wood pieces is 5:95 to 50:50. <Technology 5> The wood board according to any one of Techniques 1 to 4, wherein the wood chips have a thickness of 0.6 mm or more and a length of 15 mm or less. [Explanation of symbols]

[0029] 1. Wood board 2 Small elongated woody piece 3,4 Wood chips

Claims

1. The wood board is characterized by including small elongated wood pieces each having a thickness of 0.5 mm or less and a length along the fiber direction of 20 mm or more, and small elongated wood pieces each having a length shorter than the small elongated wood pieces, and being bonded together.

2. In claim 1, The wooden board is characterized in that the elongated wooden pieces have a width of 10 mm or less.

3. In claim 1 or 2, The wooden board is characterized in that the elongated wooden pieces have a thickness of 0.2 mm or more, a width of 1 mm or more, and a length of 50 mm or less.

4. In claim 1 or 2, A wood board characterized in that the mass ratio of the elongated wood chips to the wood chips is 5:95 to 50:

50.

5. In claim 1 or 2, The wood board is characterized in that the wood chips have a thickness of 0.6 mm or more and a length of 15 mm or less.

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