Wood board

Abstract

To provide a woody board capable of improving strength and dimensional stability while reducing weight.SOLUTION: The woody board 1 is formed by bonding and integrating a large number of slender woody small pieces 2 which are formed of conifer and have lengths along the fiber direction of 15mm or more, widths of 10mm or less, and thicknesses of 0. 5mm or less.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, Patent Document 1 lists many tree species as species that can be used for the thin wood flakes, and further improvements are desired from the standpoints of strength, dimensional stability, and the like.

[0005] The present disclosure has been made in consideration of the above-mentioned circumstances, and aims to provide a wood board that can be made lighter while improving strength and dimensional stability. [Means for solving the problem]

[0006] In order to achieve the above-mentioned objective, the wood board of the present disclosure is characterized in that it is formed by gluing together a large number of elongated wood pieces made from coniferous wood, each having a length along the fiber direction of 15 mm or more, a width of 10 mm or less, and a thickness of 0.5 mm or less. [Effects of the Invention]

[0007] The wood board according to the present disclosure has the above-described configuration, which allows for weight reduction while improving strength and dimensional stability. [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, and (b) is a schematic plan view showing an example of an elongated wood piece included in the wood board. 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 an elongated wood piece included therein.

[0010] As shown in FIG. 1( a), the wood board 1 according to this embodiment is formed by gluing together numerous elongated wood pieces 2 each having a length along the fiber direction of 15 mm or more, a width of 10 mm or less, and a thickness of 0.5 mm or less. This configuration allows the wood board 1 to be constructed from numerous relatively long elongated wood pieces 2 with little variation in shape. This allows for improved strength while still reducing weight compared to typical particle boards constructed solely from glued together wood pieces. In other words, even when maintaining the same strength as typical particle boards, the board can be made thinner and lighter, resulting in a lower density. Furthermore, the elongated wood pieces 2 that make up the wood board 1 are made from softwood. This configuration offers superior strength and dimensional stability compared to boards made from hardwood, and is also expected to facilitate the procurement of raw materials.

[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 thin wood pieces 2 included in this wood board 1 may be 20 mm or longer in length. This configuration results in better bending strength and bending Young's modulus than configurations in which the thin wood pieces 2 are too short. In other words, the aspect ratio defined by "length of thin wood pieces 2" / "width of thin wood pieces 2" is 2 or greater, and the thin wood pieces 2 are thin, as shown in Figure 1(b), so the thin wood pieces 2 can more effectively improve the strength of the wood board 1. The aspect ratio of the thin wood pieces 2 may be 2 or greater and 40 or less, or 4 or greater and 25 or less.

[0013] The elongated wood pieces 2 may have a length of 50 mm or less, a width of 1 mm or more, and a thickness of 0.2 mm or more. 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 15 mm or more (preferably 20 mm or more) to 50 mm or less. With this configuration, the elongated wood pieces 2 are less likely to be crushed or tangled during the molding process, compared to a configuration including elongated wood pieces that are too long or too small in width or thickness. More specifically, the length of the thin wood pieces 2 may be 40 mm or less. With this configuration, the peel strength is better than when the thin wood pieces 2 are too long. The width of the thin wood pieces 2 may be 5 mm or less. This configuration provides better peel strength and dimensional stability than a configuration in which the thin wood pieces 2 are too wide.

[0014] The dimensions (length, width, and thickness) of the above-mentioned 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 (length, width, and thickness) of each of these selected elongated wood pieces 2 may be measured and the average values ​​calculated. The length and width 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 (length, width, and thickness) 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.

[0015] 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, Radiata pine, etc. The long and thin wood pieces 2 included in the wood board 1 may be made of one or more tree 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.

[0016] 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.

[0017] 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.

[0018] 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.

[0019] The adhesive used to bond the numerous thin wood pieces 2 may be a thermosetting resin adhesive similar to that used in the manufacture of ordinary particle boards, such as an isocyanate adhesive, a phenolic resin, or a urea-melamine resin. Such adhesives may be applied to the thin wood pieces 2 by spraying or the like. The amount of adhesive applied (amount applied) may be approximately 5% to 15% by mass of the mass of the wood board 1.

[0020] The manufacturing method of the wood board 1 may be substantially the same as that of a general particle board, or may be another method. For example, the wood board 1 may be manufactured by stacking the adhesive-coated elongated wood pieces 2 into a mat, forming this mat into a predetermined thickness using a hot platen press, and then cutting it into appropriate widths and lengths. When stacking in a mat shape, the boards may be stacked to an appropriate mat thickness so that the wooden board 1 has a target specific gravity. For example, the mat thickness may be about 5 to 15 times the target thickness of the wooden board 1.

[0021] 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 ways.

[0022] 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 6 and Comparative Examples 1 to 6, the dimensions of the elongated wood pieces are target dimensional values ​​when manufactured using the manufacturing method described above that minimizes variability in the dimensions. In each of Examples 1 to 6 and Comparative Examples 1 to 6, wooden boards were used that were manufactured to have a total thickness of 3 mm and a specific gravity of 0.65. In each of Examples 1 to 6 and Comparative Examples 1 to 6, the adhesive used when molding the wooden boards was MDI (diphenylmethane diisocyanate), and the amount of application was 6 mass %.

[0023] In each of Examples 1 to 6, 0.2 mm thick cedar pieces were used as the elongated wood pieces formed from coniferous trees, and in each of Comparative Examples 1 to 6, 0.2 mm thick beech pieces were used as the elongated wood pieces formed from broad-leaved trees. In Example 1, small pieces of cedar having a length of 15 mm and a width of 2 mm were used. In Example 2, small pieces of cedar having a length of 30 mm and a width of 2 mm were used. In Example 3, small pieces of cedar measuring 45 mm in length and 2 mm in width were used. In Example 4, small pieces of cedar measuring 15 mm in length and 7 mm in width were used. In Example 5, small pieces of cedar having a length of 30 mm and a width of 7 mm were used. In Example 6, small pieces of cedar measuring 45 mm in length and 7 mm in width were used.

[0024] In Comparative Example 1, a small piece of beach with a length of 15 mm and a width of 2 mm was used. In Comparative Example 2, a small piece of beach having a length of 30 mm and a width of 2 mm was used. In Comparative Example 3, a small piece of beach having a length of 60 mm and a width of 2 mm was used. In Comparative Example 4, a small piece of beach having a length of 15 mm and a width of 7 mm was used. In Comparative Example 5, a small piece of beach having a length of 30 mm and a width of 7 mm was used. In Comparative Example 6, a small piece of beach having a length of 45 mm and a width of 7 mm was used.

[0025] The test specimens of the wooden boards of Examples 1 to 6 and Comparative Examples 1 to 6 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 46.3 MPa, in Example 2, 53.7 MPa, in Example 3, 55.5 MPa, in Example 4, 46.0 MPa, in Example 5, 63.0 MPa, in Example 6, 71.6 MPa, in Comparative Example 1, 26.9 MPa, in Comparative Example 2, 29.7 MPa, in Comparative Example 3, 36.4 MPa, in Comparative Example 4, 13.7 MPa, in Comparative Example 5, 13.7 MPa, and in Comparative Example 6, 21.5 MPa. <Bending Young's modulus test> In Example 1, the pressure was 4.9 GPa, in Example 2, 5.6 GPa, in Example 3, 5.7 GPa, in Example 4, 5.1 GPa, in Example 5, 6.3 GPa, in Example 6, 7.4 GPa, in Comparative Example 1, 3.2 GPa, in Comparative Example 2, 3.7 GPa, in Comparative Example 3, 4.1 GPa, in Comparative Example 4, 2.7 GPa, in Comparative Example 5, 2.4 GPa, and in Comparative Example 6, 3.5 GPa. <Peel strength test> In Example 1, the pressure was 1.6 MPa, in Example 2, 1.7 MPa, in Example 3, 1.5 MPa, in Example 4, 1.3 MPa, in Example 5, 1.5 MPa, in Example 6, 1.3 MPa, in Comparative Example 1, 1.4 MPa, in Comparative Example 2, 1.1 MPa, in Comparative Example 3, 0.9 MPa, in Comparative Example 4, 0.6 MPa, in Comparative Example 5, 0.6 MPa, and in Comparative Example 6, 0.9 MPa. <Water absorption thickness expansion rate test> In Example 1, it was 10%, in Example 2, it was 11%, in Example 3, it was 10%, in Example 4, it was 9%, in Example 5, it was 10%, in Example 6, it was 10%, in Comparative Example 1, it was 18%, in Comparative Example 2, it was 21%, in Comparative Example 3, it was 20%, in Comparative Example 4, it was 13%, in Comparative Example 5, it was 17%, and in Comparative Example 6, it was 13%. [Table 1] From the above results, Examples 1 to 6, which used cedar pieces as the elongated wood pieces, achieved better results in bending strength, Young's modulus in bending, peel strength, and thickness swelling due to water absorption than Comparative Examples 1 to 6, which used beech pieces as the elongated wood pieces. Furthermore, Examples 2, 3, 5, and 6, in which the length of the cedar pieces was greater than Examples 1 and 4, achieved better bending strength and Young's modulus in bending than Examples 1 and 4. Furthermore, Examples 2 and 5, in which the length of the cedar pieces was smaller than Examples 3 and 6, achieved better peel strength than Examples 3 and 6. Furthermore, Examples 4 and 5, in which the width of the cedar pieces was greater than Examples 1 and 2, achieved better thickness swelling due to water absorption than Examples 1 and 2. Furthermore, Examples 5 and 6, in which the width of the cedar pieces was greater than Examples 2 and 3, achieved better bending strength and Young's modulus in bending than Examples 2 and 3. Furthermore, in Examples 1 to 3, in which the width of the cedar pieces was smaller than in Examples 4 to 6, the peel strength was better than in Examples 4 to 6.

[0026] <Additional Notes> The above description of the embodiments discloses the following techniques. <Technology 1> A wood board made from coniferous trees, consisting of numerous thin, long pieces of wood glued together in the direction of the grain, each measuring 15 mm or more in length, 10 mm or less in width, and 0.5 mm or less in thickness. <Technology 2> The wood board according to claim 1, wherein the elongated wood pieces have a length of 50 mm or less, a width of 1 mm or more, and a thickness of 0.2 mm or more. <Technology 3> The wood board according to Technology 1 or Technology 2, wherein the elongated wood pieces are 20 mm or more in length. <Technology 4> The wood board according to any one of Techniques 1 to 3, wherein the elongated wood pieces have a length of 40 mm or less. <Technology 5> The wood board according to any one of Techniques 1 to 4, wherein the elongated wood pieces have a width of 5 mm or less. [Explanation of symbols]

[0027] 1. Wood board 2 Small elongated woody piece

Claims

1. The wood board is made of coniferous wood and is characterized by being formed by bonding and integrating a large number of elongated wood pieces, each having a length of 15 mm or more along the fiber direction, a width of 10 mm or less, and a thickness of 0.5 mm or less.

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

3. In claim 1 or 2, The wooden board is characterized in that the elongated wooden pieces are 20 mm or more in length.

4. In claim 1 or 2, The wooden board is characterized in that the elongated wooden pieces are 40 mm or less in length.

5. In claim 1 or 2, The wooden board is characterized in that the elongated wooden pieces have a width of 5 mm or less.

Images