Wood chipboards and flooring

Abstract

To provide a wood board exhibiting superior surface smoothness to conventional OSB, that is preferably usable for being a decorative plate by directly attaching the decorative plate thereon, as a substrate.SOLUTION: According to a cut wood flake plate 1 obtained by mixing and integrating a cut wood flake 2 and an adhesive, that is obtained by hot-press integration, at least one surface of the plate exhibits a maximum height of 200 μm or less indicating surface roughness defined by Japanese industry standard JIS B 0601: 2013. The cut wood flake having a thickness of 0.1 mm or more and 0.6 mm or less, a width of 1.0 mm or more and 50 mm or less, and a length of 15 mm or more and 200 mm or less preferably has a tree kind density of 0.6 g / cm3 or less, and a cut wood flake plate board density of 0.5 to 0.9 g / cm3. The cut wood flake plate is preferably usable for being a decorative plate 5 as a substrate by directly attaching a decorative material 4 such as a sliced veneer, a decorative sheet, or the like thereon.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a shaved wood flake board and a flooring material using the shaved wood flake board as a base material. [Background technology]

[0002] Oriented strand board (OSB, JIS A 5908:2022) is a type of wood board made by mixing small or thin pieces of wood with adhesive, assembling them, and then combining them under heat and pressure. OSB is a type of structural panel specified by JAS, but in light of the recent depletion of wood resources, there has been research into using OSB for purposes other than structural panels, such as as a base material for decorative panels. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2007-521163 Summary of the Invention [Problem to be solved by the invention]

[0004] Conventional OSB is generally manufactured by drying thin wood shavings (strands) of approximately 0.65 to 1.20 mm in thickness, applying adhesive, stacking the thin wood shavings with the grain direction set in a roughly fixed direction, and then pressurizing them into a mold. It has a density of 0.60 to 0.70 g / cm. 3 , bending strength 25~35N / mm 2 , Young's modulus of bending 3500~5000N / mm 2Although OSB has similar physical properties, uneven distribution of adhesive and uneven press loads often cause thin wood flakes to appear on the surface, resulting in poor surface smoothness, making it practically difficult to directly adhere decorative materials such as veneer or decorative sheeting to the surface of OSB. Therefore, when using OSB as a substrate for decorative boards, the current practice is to adhere a surface material with excellent surface smoothness, such as MDF, to the surface, and then adhere a decorative material such as veneer or decorative sheeting to that surface, and OSB has not previously been used alone as a base material for decorative boards.

[0005] Plywood has long been used as a base material for decorative panels, but in recent years, as high-quality veneers have become difficult to obtain, wood fiberboards such as MDF have become more widely used. Plywood has been recognized as a suitable material for use as a base material for decorative panels due to its excellent strength, low deflection, ease of application, and minimal warping or other deformation after application. However, its surface roughness is insufficient (maximum height, indicating surface roughness, exceeds 200 μm). When a thin veneer or other decorative material is directly applied to it, the unevenness of the plywood surface becomes visible on the veneer, resulting in poor surface finish and a poor walking feel when used as flooring. Therefore, when applying a decorative material to a plywood substrate, it is necessary to fill the unevenness of the plywood surface with putty to achieve a smooth surface. On the other hand, while MDF has excellent surface smoothness, it lacks bending strength, especially in the longitudinal direction.

[0006] Therefore, the problem that this invention aims to solve is to provide a wood board that has a surface smoothness equivalent to that of MDF and a bending strength greater than that of MDF, and that can be suitably used as a base material for directly attaching decorative materials such as veneer or decorative sheets to the board to make a decorative panel. [Means for solving the problem]

[0007] In order to solve this problem, the invention according to claim 1 of the present application is a shaved wood board obtained by mixing and accumulating shaved wood and adhesive, and then integrating them under heat and pressure, The density of the wood shavings is 0.6g / cm 3 and the board density is 0.5 g / cm 3 More than 0.9g / cm 3 In the area where the shavings on the surface of the wood shavings board overlap each other, both or at least one of the shavings is deformed or compressed so that the shavings are approximately flush with each other, At least one of the surfaces is characterized by having a maximum height of 200 μm or less, which indicates the surface roughness defined in Japanese Industrial Standard JIS B 0601:2013.

[0008] The invention according to claim 2 of the present application is a shaved wood board according to claim 1, wherein the wood species density of the shaved wood is 0.6 g / cm 3 The present invention is characterized by the following:

[0009] The invention according to claim 3 of the present application is that the shaved wood board according to claim 1 has a density of 0.5 g / cm 3 More than 0.9g / cm 3 It is characterized by having the following board densities:

[0010] The invention according to claim 4 of the present application is characterized in that in the shaved wood board according to claim 1, the shaved wood has a thickness of 0.1 mm or more and 0.6 mm or less.

[0011] The invention of claim 5 of the present application is characterized in that, in the wood shavings board described in any of claims 4, the width of the wood shavings is 1.0 mm or more and 50 mm or less, and the length of the wood shavings is 15 mm or more and 200 mm or less.

[0012] The invention according to claim 6 of the present application is characterized in that the shaved wood flake board according to claim 1 comprises three layers: a surface layer, a core layer, and another surface layer.

[0013] The invention of claim 7 of the present application is characterized in that, in the wood shavings board described in claim 6, the orientation of the core layer is approximately perpendicular to the longitudinal direction of the wood shavings board, and the orientation of the two surface layers is approximately parallel to the longitudinal direction of the wood shavings board.

[0014] The invention according to claim 8 of the present application is a flooring material in which a decorative material is laminated on the surface of the shaved wood chipboard according to any one of claims 1 to 7, the maximum height of which indicates the surface roughness of which is 200 μm or less, and the bending strength is 30 to 80 N / mm 2 and the bending Young's modulus is 3000 to 8500 N / mm 2It is characterized in that: [Effects of the Invention]

[0015] According to the present invention, a shaved wood flake board is provided which has a surface smoothness that is significantly improved over conventional OSB, is comparable to or equal to MDF, which is known to have good surface smoothness, and has excellent physical properties. Therefore, the shaved wood flake board of the present invention can be suitably used instead of conventional MDF, etc., as a substrate for directly attaching a decorative material such as veneer or decorative sheet to the shaved wood flake board to make a decorative board.

[0016] Even if the wood shavings of the present invention are randomly accumulated without any specific orientation, they can have various physical properties such as bending strength suitable for use as a base material for decorative panels by adjusting the tree species density of the wood shavings and the board density. In a three-layer laminated structure, by giving the core layer an orientation that is approximately perpendicular to the longitudinal direction of the wood shavings and the two surface layers an orientation that is approximately parallel to the longitudinal direction of the wood shavings, the bending strength can be further increased and the length expansion rate can be reduced, improving dimensional stability.

[0017] A flooring material made by laminating a decorative material such as veneer on the smooth surface of this shaved wood flake board has good density and bending Young's modulus, and is excellent in strength, rigidity, scratch resistance, etc. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a side view schematically showing a shaved wood board according to the present invention. FIG. [Figure 2] 1 is a side view schematically showing a flooring material using the shaved wood flake board according to the present invention as a base material. [Figure 3] FIG. 1 is a diagram showing measurement points for a surface roughness test in a test example. [Figure 4]Schematic cross-sectional views of thick wood shavings with low tree species density (a), thin wood shavings with low tree species density (b), thick wood shavings with high tree species density (d), and thin wood shavings with high tree species density (e), as well as schematic cross-sectional views of thin wood shavings (b, e) after compression (c, f). [Figure 5] Schematic cross-sectional views showing a mat (a) made of wood shavings with a low tree species density and its compressed state (b), and a mat (c) made of wood shavings with a high tree species density and the state (d) of these mats compressed and cut vertically at both ends of the width direction. [Figure 6] Schematic cross-sectional views showing the surface condition (a) of a portion where wood shavings with a low species density overlap each other before compression and the surface condition (b) of that portion after compression, and the surface condition (c) of a portion where wood shavings with a high species density overlap each other before compression and the surface condition (d) of that portion after compression. [Figure 7] 1 is a graph showing the correlation between the density of the tree species used as the wood shavings and the maximum height indicating the surface roughness of the resulting wood shavings board. [Figure 8] 1 is a graph showing the correlation between the board density of shaved wood flake board and the maximum height indicating the surface roughness. BEST MODE FOR CARRYING OUT THE INVENTION

[0019] The present invention relates to a shaved wood board obtained by mixing and accumulating wood shavings with an adhesive, and then thermocompressing and integrating them. Fig. 1 is a cross-sectional view showing this shaved wood board 1 alone, with the reference numeral 2 indicating wood shavings. Fig. 2 is a cross-sectional view showing a flooring material 4 (decorative board) in which this shaved wood board 1 is used as a substrate and veneer 3 (decorative material) is laminated and bonded onto its smooth surface.

[0020] Wood shavings are prepared by thinly cutting hardwood or softwood logs with a strander. Wood shavings may also be obtained from planted, renewable hardwoods or softwoods.

[0021] The wood shavings used in the wood shavings board of the present invention have a thickness of 0.1 mm to 0.6 mm and a width of 100 mm. 1mmThe length is between 15mm and 200mm.

[0022] If the thickness of the wood shavings is less than 0.1 mm, the wood shavings production capacity will decrease, and if it exceeds 0.6 mm, the surface smoothness of the resulting wood shavings board will decrease and the rigidity will be uneven.If the thickness of the wood shavings is within the range of 0.1 mm to 0.6 mm, the wood shavings board will have excellent surface smoothness and uniform rigidity.

[0023] If the width of the wood shavings exceeds 50 mm, not only will they be difficult to handle and transport, but they will also be prone to curling, making them less likely to adhere to adhesives. 1mm If the width of the shavings is less than 1 / 2, the rigidity of the resulting shavings board will decrease. 1mm If the thickness is within the range of 50 mm or less, the wood flake board can have excellent surface smoothness and uniform rigidity.

[0024] If the length of the wood shavings exceeds 200 mm, not only will handling and transportability be impaired, but the wood shavings will also be prone to curling, which will create localized cavities (core voids) when heated and pressed, reducing strength and causing punctures. If the length of the wood shavings is less than 15 mm, the rigidity of the resulting wood shavings board will be reduced. If the length of the wood shavings is within the range of 15 mm to 200 mm, the productivity of the wood shavings board will be excellent and it will be easier to achieve the required rigidity.

[0025] The moisture content of the wood shavings is preferably 15% by weight or less, and they are dried to this moisture content or less before entering the wood shavings board manufacturing process. If the moisture content exceeds 15% by weight, an extremely high-density layer is likely to form on the surface of the wood shavings board, which requires a long time for pressing during pressure molding and results in uneven rigidity of the resulting wood shavings board. From this perspective, it is more preferable for the moisture content of the wood shavings to be 3% by weight or less. The moisture content MC of wood shavings can be calculated using the formula MC = (m1 - m0) x 100 / m0 in accordance with Japanese Industrial Standard JIS A 5905:2022 7.5. Here, m1 is the mass (g) of the wood shavings sample before drying, and m0 is the mass (g) of the wood shavings sample when placed in an air dryer at 103°C and brought to constant weight.

[0026] The adhesive applied to the wood shavings can be thermosetting resins such as urea resin, melamine urea resin, phenolic resin, polyurethane resin, or epoxy resin, either alone or in combination. Mixing these with polyisocyanates is particularly preferable, as it reduces formaldehyde emissions and improves physicochemical properties such as bending strength. Polyisocyanates are compounds containing two or more isocyanate groups per molecule, such as diisocyanate compounds like 4,4'-diphenylmethane diisocyanate (MDI) and compounds obtained by reacting an excess of a diisocyanate compound with a polyol. One example of a polyisocyanate is polymeric MDI (polymethylene polyphenyl polyisocyanate: a mixture of monomeric MDI and high-molecular-weight polyisocyanate, also known as crude MDI), which hardens or foams upon reaction with moisture.

[0027] The amount of adhesive used is preferably 4 to 30 parts by weight in solids per 100 parts by weight of bone-dry wood shavings. If the amount of adhesive solids per 100 parts by weight of bone-dry wood shavings is less than 4 parts by weight, the bending strength of the wood shavings board will decrease, and if it exceeds 30 parts by weight, it will be an excessive amount, causing excessive rigidity and being economically disadvantageous. When an isocyanate compound is used as the adhesive, the solids content should preferably be 4 to 12 parts by weight, and when a melamine urea resin is used, the solids content should preferably be 10 to 30 parts by weight.

[0028] Next, a method for manufacturing a shaved wood board according to the present invention will be described. Generally speaking, the shaved wood board according to the present invention is manufactured by drying the shaved wood, applying an adhesive, randomly stacking the shaved wood without specifying the grain direction, and then pressurizing and molding this stack (mat). This will be described in more detail below.

[0029] Plantable hardwood or softwood logs, waste wood, sawmill waste, recycled materials, etc. are prepared and cut with a strander (cutting machine) to produce shaved wood. As described above, the shaved wood used in the shaved wood board of the present invention has a thickness of 0.1 mm to 0.6 mm and a width of 100 mm. 1mm The wood shavings are cut to meet these dimensional requirements and are made into thin wood shavings.

[0030] Next, the wood shavings are dried in a dryer to a moisture content of 15% or less, preferably 3% or less, and then an adhesive is applied to the surface. The adhesive can be applied, for example, by a spray method, for example, by putting the wood shavings into a rotating drum rotating at a low speed (about 30 rpm) and spraying the adhesive onto the wood shavings as they fall naturally inside the rotating drum.

[0031] The adhesive-coated wood shavings are then piled up and formed into a mat, which is then thermocompressed in a press. The heat from the thermocompression process hardens the thermosetting resin in the adhesive, firmly bonding the wood shavings together to produce a shaved wood board. The thermocompression temperature varies depending on the type of adhesive used, but is generally between 190 and 220°C.

[0032] When collecting and forming wood shavings into a mat, they may be formed into a single mat, or the wood shavings may be divided into multiple groups, for example, three groups, and each group may be formed into a mat, which may then be stacked and thermo-compressed to produce a wood shavings board consisting of three layers: surface layer, core layer, and surface layer. Wood shavings boards produced by thermo-compressing a single-layer mat may have unevenness in the wood shavings, but by forming multiple layers, the unevenness in the wood shavings can be dispersed or eliminated, resulting in uniform strength and rigidity.

[0033] The wood chipboard produced in this way has a density of 0.5 to 0.9 g / cm 3 It is preferable that the density is 0.5 g / cm 3 If the thickness is less than 0.9 g / cm3, the strength of the wood chip board will be insufficient, while the density will be 3 If the density is larger than this, the weight of the entire wood chipboard increases, making it difficult to handle. 3 Within this range, various properties suitable for flooring and other indoor interior materials can be obtained.

[0034] Regarding the density distribution of the shaved wood board, by using shaved wood boards with a moisture content of 15% by weight or less, more preferably 3% by weight or less, it is possible to effectively prevent the formation of a high-density layer on the surface of the shaved wood board, and further, by adjusting the timing and pressure at which the hot platen is brought into contact with the shaved wood board during hot pressing, it is possible to keep the density distribution at 0.5 to 0.9 g / cm. 3 The density profile in the thickness direction can be measured using a density distribution measuring instrument (DAX5000, manufactured by Grecon GmbH, Germany).

[0035] In addition, the bending strength of wood flakes is 25 to 90 N / mm 2 , bending Young's modulus is 3000~8500N / mm 2 It is preferable that the bending strength is 25 N / mm 2 and / or bending Young's modulus is less than 3000N / mm 2 If the bending strength is less than 90N / mm, the deflection will be greater than the deflection standard (3.5mm or less, see below) set by the JAS wood flooring standard, especially when the wood chipboard is used as a base material for flooring, making it unsuitable for use as a flooring material. 2 and / or bending Young's modulus 8500N / mm 2 If the bending strength is more than 25-90N / mm, the elasticity required for walking when used as a flooring material will be insufficient, resulting in a poor walking feel. 2 The Young's modulus of bending is within the range of 3000 to 8500 N / mm 2 Within this range, the wood flake board can be made suitable for use as a base material for flooring.

[0036] Furthermore, flooring can be produced by using the shaved wood flakes produced as described above as a substrate and laminating and adhering a decorative material, such as veneer, decorative sheet, or decorative paper, approximately 0.1 to 0.2 mm thick onto its surface using an F☆☆☆☆ grade adhesive as specified in Table 3 of the Japanese Industrial Standard JIS A 5536:2015 "Adhesives for Floor Finishes." A coating layer, such as a urethane coating, approximately 20 to 80 μm thick may also be formed on the surface of the decorative material. Because the surface of the shaved wood flakes is smooth, the flooring obtained by laminating and adhering a decorative material onto the smooth surface also has a smooth surface and possesses appropriate physical properties such as strength, elasticity, and flexure, making it an ideal flooring material.

[0037] Examples of the present invention and comparative examples are explained below with reference to test examples. In these test examples, each piece was thinly cut from a cypress log using a strander (cutting machine) to a thickness of 0.1 mm to 0.6 mm, a length of 15 mm to 200 mm, and a width of 1.5 mm. 1mmA large number of wood shaving samples with a diameter of 50 mm were prepared, and these were weighed to a predetermined weight ratio and divided into three groups (top layer sample a, core layer sample b, and bottom layer sample c). In Example 1, the top layer sample a was 30%, the core layer sample 40%, and the bottom layer sample 30% by bone-dry weight ratio of the wood shavings. In Example 2, the top layer sample was 25%, the core layer sample 50%, and the bottom layer sample 25% by bone-dry weight ratio of the wood shavings.

[0038] A resin adhesive containing polyisocyanate (Sumidur 44 (registered trademark) V20, a product of Sumika Covestro Urethane Co., Ltd.) was applied to the surface of each of the wood shavings for the upper layer sample a, the core layer sample b, and the lower layer sample c. The application was performed using a spray method, where the wood shavings for sample a were placed into a rotating drum rotating at a low speed (approximately 30 rpm), and the resin adhesive containing polyisocyanate was sprayed onto the wood shavings as they naturally fell inside the rotating drum. The adhesive was sprayed onto samples b and c in the same manner.

[0039] The upper layer sample a, the core layer sample b, and the lower layer sample c were each stacked in a mat shape to form the upper layer mat A, the core layer mat B, and the lower layer mat C, which were then laminated in order at a surface pressure of 3 to 10 N / mm 2 The wood was then hot-pressed at a temperature of 190 to 220°C for 2 to 4 minutes to obtain shaved wood flake board specimens (Examples 1 and 2) measuring 300 mm long x 300 mm wide x 12 mm thick.

[0040] For comparison, plywood, which has traditionally been widely used as a base material for flooring, and commercially available OSB (made from thin wood chips with a thickness of 0.65 to 1.20 mm) were used as comparative examples. The dimensions of these comparative examples were 300 mm x 300 mm x 12 mm thick, the same as in Examples 1 and 2.

[0041] For each of these examples and comparative examples (hereinafter collectively referred to as "test specimens"), the density, longitudinal bending strength, longitudinal bending Young's modulus, and maximum height were measured using a surface roughness measuring device (JIS B 0651:2001, Surftest SJ-310, manufactured by Mitutoyo Corporation). The results of these measurements are shown in Table 1. The measurement points for maximum height, which indicates surface roughness, were determined by dividing a test specimen with planar dimensions of 300 mm x 300 mm into nine 100 mm x 100 mm regions, as shown in Figure 3, and the centers of each region were designated as measurement points 1 to 9. Specifically, a measuring device was placed on the surface of each test specimen, and a stylus set at each measurement point was automatically measured to measure the unevenness at 0.01 mm intervals as it moved along a 15 mm linear range. The uneven shape was measured by calculating the maximum height within the measurement range (JIS B 0601:2013, the distance from the bottom of the deepest recess to the top of the highest protrusion, Rz = Rv + Rq), and the average value of the maximum height measured at each measurement point is shown in Table 1.

[0042] [Table 1]

[0043] Each of these test specimens was used as a substrate, and a 0.2 mm thick sliced ​​veneer was laminated and glued onto the surface to obtain flooring materials. The results of a visual evaluation of the surface condition are also shown in the rightmost column of Table 1. In this visual evaluation, a circle indicates that the veneer surface was in good condition, with no irregularities from the substrate surface visible, a triangle indicates that the veneer surface was in a slightly poor condition, with only slight irregularities from the substrate surface visible, and an cross indicates that the veneer surface was in a poor condition, with many irregularities from the substrate surface visible.

[0044] As can be seen from the results shown in Table 1, the maximum heights of the wood chipboards in Examples 1 and 2 of the present invention, which indicate surface roughness, are 114 μm and 118 μm, respectively, and have surface smoothness that is significantly better than that of the plywood and OSB in the comparative examples.Therefore, even when this is used as a base material and a thin veneer is attached to its surface to make a flooring material, it has been confirmed that a good surface condition can be obtained without any unevenness appearing on the surface of the veneer.

[0045] In addition, the shaved wood flakes of Examples 1 and 2 of the present invention also have excellent physical properties such as density, bending strength, and bending Young's modulus. Although not shown in the table, the bending deflection standard of the JAS wood flooring standard (a flooring sample measuring 300 mm wide x 1800 mm long x 12 mm thick is supported at a span of 700 mm, and a load of 21 kg is applied to a load rod placed in the center of the span. The amount of displacement A is measured, and the amount of displacement B is measured when a load of 9 kg is applied. The difference in the amount of displacement AB must be 3.5 mm or less) was AB = 1.9 mm, which met the standard. From the above results, it was confirmed that the shaved wood flakes of Examples 1 and 2 of the present invention have various physical properties suitable for use as a flooring base material.

[0046] Regarding the good surface smoothness obtained in the wood shavings boards of Examples 1 and 2 of the present invention, it is speculated that the reasons for this include the fact that the wood shavings used were relatively thin, the cypress tree species density was low, making them easy to compress, and the wood shavings boards were manufactured by sufficient compression.

[0047] More specifically, the compressive deformation of wood shavings will be explained with reference to Figure 4. As shown in Figures 4(a) to (c), when the tree species density is low, the proportion of woody parts 2a in the wood shavings is relatively small and the proportion of voids 2b is large, making the wood shavings more susceptible to compression. When wood shavings are cut thinly (Figure 4(b)), the presence of voids tends to cause surface irregularities, but the voids are crushed by compression, reducing the surface irregularities (Figure 4(c)). On the other hand, as shown in Figures 4(d) to (f), when the tree species density is high, the proportion of voids 2b in the wood shavings is small, and the woody parts 2a occupy the majority of the wood shavings, increasing the strength, making the wood shavings less susceptible to compression (Figure 4(f)) even when the wood shavings are thin (Figure 4(e)).

[0048] Next, the deformation of the surface of the shaved wood board will be explained with reference to Figure 5. In order to create a shaved wood board with the same board density, if a shaved wood board with a low tree species density (2c) is used, it is necessary to accumulate a large number of shaved wood boards (2c) to increase the mat volume (Figure 5(a)). However, a mat made of accumulated shaved wood boards with a low tree species density (2c) is easily compressed, so when it is hot-pressed, its surface conforms to the smooth press surface, resulting in a shaved wood board with a smooth surface (Figure 5(b)). On the other hand, to create a shaved wood board with the same board density using shaved wood boards with a high tree species density (2d), it is necessary to reduce the amount of shaved wood boards (2d) used and reduce the mat volume (Figure 5(c)). However, a mat made of accumulated shaved wood boards with a high tree species density (2d) is difficult to compress, so when it is hot-pressed, its surface conforms poorly to the smooth press surface, resulting in a shaved wood board with large irregularities and poor surface smoothness (Figure 5(d)).

[0049] Although it is inevitable that the surface of the wood shavings board will tend to become uneven where the wood shavings overlap, as shown in Figures 6(a) and (b), since the wood shavings 2c with a low tree species density are weak in strength and easily compressed, it is assumed that both or at least one of the overlapping wood shavings 2c, 2c will deform or compress, making them approximately flush, and maintaining the surface smoothness without generating large unevenness. To achieve this effectively, relatively thin wood shavings with a thickness of 0.1 to 0.6 mm are used, and when the mat made by accumulating these wood shavings is thermocompressed, the overlapping wood shavings are compressed with a compressive force of 0.6 to 0.8 g / cm to make them approximately flush. 3It is preferable to form the shaved wood board into a board density of about 100 μm. By doing so, the height of the step 5 formed at the overlapping portion of the shaved wood board obtained after compression is 0.2 mm or less, making it easy to obtain a shaved wood board with a maximum height of 200 μm or less, which indicates surface roughness. On the other hand, when shaved wood boards 2d with a high tree species density overlap, as shown in Figures 6(c) and (d), the overlapping shaved wood boards 2d, 2d are barely deformed and remain overlapped, leaving a step, and the height of the step 5 becomes greater than 0.2 mm, making it difficult to obtain a shaved wood board with a maximum height of 200 μm or less, which indicates surface roughness.

[0050] Based on these assumptions, we thought that the surface smoothness of shaved wood boards has a strong correlation with the thickness of the shaved wood used as raw material, the tree species density, and the board density. Here, it is generally known or easily conceivable that stacking relatively thin shaved wood boards reduces the unevenness caused by the overlapping parts (improving the surface smoothness), so we investigated the influence or correlation of the tree species density and board density on the surface roughness.

[0051] First, the following test was carried out to confirm the influence of the tree species density of the wood shavings on the surface roughness. That is, wood shavings from six types of tree species, namely, sawtooth oak, zelkova, edulis, loblolly pine, cypress, and cedar, were used individually as the wood shavings, and six types of wood shavings board specimens of different tree species were prepared in the same manner as in Example 1. As mentioned above, it was assumed that the surface roughness is also related to the board density, so the test was carried out when the board density was approximately constant (about 0.7 g / cm 3 Each specimen was prepared so that the maximum height of the surface roughness was 1 / 4 of the original height. The surface roughness of each specimen was measured in the same manner as above, and the results of a visual evaluation of the surface condition of the flooring material, in which a 0.2 mm thick sliced ​​veneer was laminated and glued to the surface of each specimen, are shown in Table 2. Figure 7 also shows a graph of the correlation between wood species density and maximum height of surface roughness.

[0052] [Table 2]

[0053] From the results shown in Table 2 and Figure 7, a certain correlation was found between the density of the tree species used as the wood shavings and the maximum height, which indicates the surface roughness of the wood shavings boards made using them.The lower the tree species density, the smaller the maximum height, which indicates the surface roughness (better surface smoothness). Conversely, the higher the tree species density, the larger the maximum height, which indicates the surface roughness (decreasing surface smoothness).

[0054] More specifically, a density of 0.6 g / cm 3 The shaved wood boards made from shaved wood from the most common tree species (oak, zelkova, and edulis) had a maximum height indicating surface roughness of over 200 μm, and had poor surface smoothness, similar to plywood. As a result, the surface condition of the flooring material obtained by laminating and gluing veneer onto the surface was also poor (x) or slightly poor (△).

[0055] In contrast, the density is 0.6 g / cm 3 The shaved wood boards made from shaved wood of the following tree species (loblolly pine, cypress, and cedar) had a maximum height indicating surface roughness of 200 μm or less, and had a surface smoothness better than plywood. The surface condition of the flooring material obtained by laminating and gluing veneer to the surface was also good (○). Furthermore, the density was 0.45 g / cm 3 The maximum height of the shaved wood boards made from the shaved wood of the following tree species (Japanese cypress and Japanese cedar) was less than 100 μm, and they had very good surface smoothness.

[0056] Next, the following test was conducted to confirm the effect of board density on surface roughness. Since the above confirmed that surface roughness is related to the species density of the wood shavings, nine specimens with different board densities were prepared in the same manner as in Example 1, except that cedar shavings, which have a low species density and are therefore soft and easily compressible, were used in this test, and the heat and pressure conditions on the mat were varied to achieve various board densities. The surface roughness of each specimen was measured in the same manner as above, and the results of visual evaluation of the surface condition of flooring materials with 0.2 mm thick sliced ​​veneer laminated and bonded to the surface of each specimen are shown in Table 3. The correlation between board density and maximum surface roughness height is also shown in a graph in Figure 8.

[0057] [Table 3]

[0058] From the results shown in Table 3 and Figure 8, a certain correlation was found between the board density of shaved wood flake boards and the maximum height indicating surface roughness, with a tendency for the higher the board density, the smaller the maximum height indicating surface roughness (better surface smoothness), and conversely, the lower the board density, the larger the maximum height indicating surface roughness (decreasing surface smoothness).

[0059] More specifically, board density is 0.5 g / cm 3 The smaller test specimens (cedar 8 and 9) had a maximum height indicating surface roughness of over 200 μm, and had poor surface smoothness, similar to that of plywood. Therefore, the surface condition of the flooring material obtained by laminating and gluing veneer onto the surface was also poor (x).

[0060] In contrast, the board density is 0.5g / cm 3 End The test specimens (cedar 1 to 7) had a maximum height of 200 μm or less, which indicates surface roughness, and had a surface smoothness better than that of plywood. The surface condition of the flooring material obtained by laminating and gluing veneer to the surface was also good (◯). In this test, the upper limit of the board density of the test specimens was set to 0.86 g / cm 3(Cedar 1), but the board density is 0.9g / cm 3 If the board density exceeds 0.9g / cm, the weight increases and handling becomes difficult, and it also has a negative effect on the feeling of walking when used as a flooring material. 3 is preferably set as the upper limit.

[0061] Although the present invention has been described in detail above with reference to test examples, the present invention can be practiced with a wide variety of modifications and alterations within the scope of the invention as defined by the claims. [Explanation of symbols]

[0062] 1 Wood cut thin plate (base material) 2 Wood cutting thin section 2a Woody part 2b Cavity 2c Wood shavings with low species density 2d Wood shavings with high species density 3 Veneer (decorative material) 4 Flooring (decorative panels) 5. Steps on the surface of the wood shavings board formed where the wood shavings overlap

Claims

1. A shaved wood board obtained by mixing and aggregating wood shavings with an adhesive, and then thermocompressing and integrating the mixture, characterized in that the wood shavings have a tree species density of 0.6 g / cm 3 or less, the board density is 0.5 g / cm 3 or more and 0.9 g / cm 3 or less, and in areas where the shaved wood flakes on the surface of the shaved wood board overlap each other, both or at least one of the shaved wood flakes are deformed or compressed so that the shaved wood flakes become approximately flush with each other, and at least one surface has a maximum height of 200 μm or less, indicating the surface roughness defined in Japanese Industrial Standard JIS B 0601:2013.

2. The density of the wood shavings is 0.6 g / cm ３ 2. The shaved wood board according to claim 1, characterized in that:

3. 0.5 g / cm ３ 0.9g / cm or more ３ 2. The shaved wood board of claim 1, characterized in that it has a board density of:

4. 2. The shaved wood board according to claim 1, wherein the shaved wood has a thickness of 0.1 mm to 0.6 mm.

5. 5. The wood shavings board according to claim 4, wherein the width of the wood shavings is 1.0 mm or more and 50 mm or less, and the length of the wood shavings is 15 mm or more and 200 mm or less.

6. 2. The shaved wood flake board according to claim 1, comprising three layers: a surface layer, a core layer, and another surface layer.

7. The shaved wood flake board according to claim 6, characterized in that the orientation of the core layer is approximately perpendicular to the longitudinal direction of the shaved wood flake board, and the orientation of the two surface layers is approximately parallel to the longitudinal direction of the shaved wood flake board.

8. A flooring material obtained by laminating a decorative material on the surface of the shaved wood chipboard according to any one of claims 1 to 7, which has a maximum height indicating the surface roughness of 200 μm or less, and having a bending strength of 30 to 80 N / mm ２ and the bending Young's modulus is 3000 to 8500 N / mm ２ A flooring material characterized by:

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