Wood chipboard and its manufacturing method

Abstract

To provide a wooden board which has superior surface smoothness than conventional OSB and which can be suitably used as a substrate serving as a decorative board by adhering a decorative material directly on itself.SOLUTION: A wood chip lamina board 1 has an average value of 40 μm or less of a maximum height showing surface roughness defined by Japanese Industrial Standards JIS B 0601:2013 and a maximum value of 50 μm or less. A first wood chip lamina group consisting of an aggregation of wood chip laminas 2 having a thickness of 0.6 mm or less and a second wood chip lamina group consisting of the aggregation of wood chip laminas 3 having the thickness of greater than 0.6 mm or more are prepared, 68 wt% or more, preferably 70 wt% or more, of the first wood chip lamina group to a total amount of the first and second wood chip lamina groups is mixed to obtain a raw material wood chip lamina, adhesive agent is applied, mixed, aggregated on the raw material wood chip lamina, integrated by hot pressing and manufactured. The wood chip lamina board can be suitably used as a substrate serving as a decorative board 5 by adhering a decorative material 4 such as a veneer or decorative sheet directly on itself.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a shaved wood board and a method for producing the same. [Background technology]

[0002] Oriented strand board (OSB) is a type of wood board made by mixing small or thin pieces of wood with adhesive, piling them up, and then combining them under heat and pressure. OSB is a type of structural panel specified by JAS, and is standardized as a type of particle board by JIS. However, with the recent depletion of wood resources, there is also research underway 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 laminating numerous 0.7 to 1.2 mm thick wood shavings together in an overlapping state using a thermosetting resin adhesive, and then pressing this laminate at high temperature to form a board. However, due to uneven distribution of the adhesive and uneven pressing load, some of the wood shavings often appear to be curled up on the surface, and the surface is poor in smoothness, making it practically difficult to directly attach decorative materials such as veneer or decorative sheet to the surface of OSB. Therefore, when using OSB as a substrate for decorative boards, a surface material with excellent surface smoothness, such as MDF, is attached to the surface, and then a decorative material such as veneer or decorative sheet is attached to that surface to form the decorative board. However, OSB has not previously been used alone as a base material for decorative boards.

[0005] Therefore, the problem that the present invention aims to solve is to provide a wood board with improved surface smoothness that can be used as a base material for directly attaching decorative materials such as veneer or decorative sheets to the board to make a decorative board. [Means for solving the problem]

[0006] In order to solve this problem, the invention according to claim 1 of the present application is as follows: Wood shavings obtained by cutting wood, 10-200mm long, 1-50mm wide, and 0.6mm thick or less, and 10-200mm long, 1-50mm wide, and more than 0.6mm thick and an adhesive are mixed and accumulated, and then heat-pressed and integrated to obtain a shaved wood board, The wood shavings are stacked one on top of the other, and the surface of the wood shavings board is formed by compressed wood shavings. It is characterized by having an average maximum height of 40 μm or less and a maximum value of 50 μm or less, which indicates the surface roughness defined in Japanese Industrial Standard JIS B 0601:2013.

[0007] The invention of claim 2 of the present application is a method for producing a wood shavings board, characterized in that a first wood shavings group consisting of an aggregate of wood shavings having a thickness of 0.6 mm or less and a second wood shavings group consisting of an aggregate of wood shavings having a thickness of more than 0.6 mm are prepared, and the first wood shavings group is used to form raw wood shavings at 68% by weight or more of the total blend amount, which is the sum of the first wood shavings group and the second wood shavings group, and an adhesive is applied to these raw wood shavings, mixed, accumulated, and then thermo-pressed together.

[0008] The invention according to claim 3 of the present application is characterized in that in the method for manufacturing a shavings board according to claim 2, the first shavings group includes shavings generated when obtaining the shavings.

[0009] The invention according to claim 4 of the present application is a shaved wood board manufactured by the manufacturing method according to claim 2 or 3. [Effects of the Invention]

[0010] 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 a board or decorative sheet to form a decorative board. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a side view schematically showing a wood flake board according to the present invention. [Figure 2] 1 is a side view schematically showing a decorative board using a wood flake board according to the present invention as a substrate. [Figure 3] FIG. 1 is a diagram showing measurement points for a surface roughness test in a test example. BEST MODE FOR CARRYING OUT THE INVENTION

[0012] The present invention relates to a shaved wood board obtained by mixing and accumulating wood shavings with an adhesive, and then thermocompressing the mixture. Fig. 1 is a cross-sectional view of this shaved wood board 1 alone, with reference numeral 2 indicating wood shavings with a thickness of 0.6 mm or less and reference numeral 3 indicating wood shavings with a thickness of more than 0.6 mm. Fig. 2 is a cross-sectional view of a decorative board 5 obtained by using this shaved wood board 1 as a substrate and adhering a decorative material 4 onto it.

[0013] Wood shavings are prepared by thinly cutting hardwood or softwood logs with a flaker. Wood shavings may also be obtained from planted, renewable hardwoods or softwoods.

[0014] The moisture content of 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, requiring a long time for pressing during pressure molding. The moisture content of wood shavings can be calculated using the formula (m1-m0) x 100 / m0 in accordance with Japanese Industrial Standard JIS A 5905-2003 6.4. 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.

[0015] The wood shavings used for wood shaving boards are 10 to 200 mm in length and 1 to 200 mm in width. 50mm If the length of the wood shavings exceeds 200 mm, they will curl when they dry, and if they are heated and pressed in this curled state, localized voids will form, causing poor adhesion and resulting in punctures or poor strength.

[0016] As mentioned above, conventional OSB uses wood shavings with a thickness of 0.7 to 1.2 mm. In the present invention, a first wood shavings group consisting of a collection of wood shavings with a thickness of 0.6 mm or less and a second wood shavings group consisting of a collection of wood shavings with a thickness of more than 0.6 mm are prepared. The first wood shavings group is mixed with an adhesive at a ratio of 68% by weight or more, preferably 70% by weight or more, and more preferably 80% by weight or more of the total weight of the first and second wood shavings groups. That is, if the weight of the first wood shavings group is A and the weight of the second wood shavings group is B, the mixture is used so that A / (A+B) ≥ 68%, preferably ≥ 70%, and more preferably ≥ 80%. This point will be explained in detail later with test examples. The reason for classifying the first wood shavings group and the second wood shavings group at a thickness of 0.6 mm is as follows.

[0017] As mentioned above, conventional OSB was primarily intended for use as a structural panel, not as a base material for attaching decorative materials such as veneer or decorative sheeting to the surface to create a decorative board. Therefore, the raw material for OSB was wood shavings with a thickness of 0.6 mm or more, primarily 0.7 to 1.2 mm, which can be produced with relatively low cost and high productivity. While it would be expected that reducing the thickness of the wood shavings used as raw material would improve the surface smoothness for use as a base material for decorative boards, the thinner the wood shavings, the more bulky they become, making management difficult and increasing costs, making this approach uncommon. Furthermore, when attempting to produce OSB using only thin wood shavings with a thickness of 0.6 mm or less, the mats would become unstable on the production line, often tilting, collapsing, or tipping over, causing line stoppages. Therefore, in the present invention, we have focused on the fact that by using wood shavings with a thickness of more than 0.6 mm (thickness 0.7 to 1.2 mm) that have been commonly produced in the past, and by blending or mixing a certain amount of thinner wood shavings, it is possible to produce wood shavings boards with surface smoothness that can be suitably used as a base material for decorative panels at relatively low cost and efficiently.

[0018] Furthermore, the wood shavings of the first wood shavings group, which are 0.6 mm or less thick, are assumed to have an average thickness of approximately 0.35 mm, and if they are compressed to half their thickness by heat and pressure, or if the wood shavings are sandwiched between each other by half their thickness, the average depth of irregularities on the surface of the resulting wood shavings board is expected to be approximately 0.175 mm. When this wood shavings board is used as the base material for a decorative board, the decorative material such as veneer or decorative sheet attached to the surface is generally 0.2 mm or thicker, so even if there are irregularities of about 0.175 mm on the surface of the wood shavings board, these can be absorbed by attaching a decorative material with a thickness that exceeds this unevenness depth, and irregularities are less likely to appear on the decorative surface. On the other hand, if the upper limit of the thickness of the wood shavings constituting the first wood shavings group is larger (for example, 0.7 mm), the unevenness appearing on the surface of the resulting wood shavings board will be approximately the same as or larger than the thickness of the decorative material, and even if the decorative material is attached, it will not be able to absorb the surface unevenness, resulting in unevenness appearing on the decorative surface, which will significantly impair the commercial value of the decorative board.For this reason, when classifying the first wood shavings group and the second wood shavings group, a thickness of 0.6 mm is used as the standard, and wood shavings with a thickness of 0.6 mm or less are classified as the first wood shavings group, and wood shavings with a thickness of more than 0.6 mm are classified as the second wood shavings group.

[0019] The adhesive applied to the wood shavings can be a thermosetting resin such as urea resin, melamine urea resin, phenolic resin, polyurethane resin, or epoxy resin, either alone or in combination. However, polyurethane resin or melamine urea resin is preferred, as it shortens the press time during pressure molding and improves the water resistance of the molded product. As the polyurethane resin, an isocyanate compound having two or more isocyanate groups in the molecule, such as crude diphenylmethane-4,4'-diisocyanate (Sumidur 44V20, a product of Sumika Covestro Urethane Co., Ltd.), can be used.

[0020] 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, making it unsuitable as a base material for decorative laminates. If it exceeds 30 parts by weight, the amount will be excessive, resulting in more rigidity than necessary and being economically disadvantageous. More specifically, if an isocyanate compound is used as the adhesive, the solids content should preferably be 4 to 12 parts by weight, and if a melamine urea resin is used, the solids content should preferably be 15 to 25 parts by weight.

[0021] Next, the method for manufacturing the wood shavings board according to the present invention will be described. As described above, a first wood shavings group consisting of an aggregate of wood shavings with a thickness of 0.6 mm or less and a second wood shavings group consisting of an aggregate of wood shavings with a thickness of more than 0.6 mm are mixed so that the first wood shavings group accounts for 70% by weight or more, preferably 80% by weight or more, of the total amount of the first wood shavings group and the second wood shavings group combined to prepare raw wood shavings, and then the adhesive described above is applied to the surface and mixed. A spray method can be used as the application method. For example, the raw wood shavings are placed in a rotating drum rotating at a low speed, and the adhesive is sprayed onto the raw wood shavings as they fall naturally from the rotating drum.

[0022] Next, the adhesive-coated raw wood shavings are formed into a mat and then thermocompressed in a press. The heat from the thermocompression hardens the thermosetting adhesive, firmly bonding the raw wood shavings together to produce a wood shavings board. The thermocompression temperature varies depending on the type of adhesive used, but is generally between 150 and 230°C.

[0023] The shaved wood board manufactured in this way has a significantly improved surface smoothness compared to conventional OSB, and a density distribution of 0.3 to 0.95 g / cm3, as demonstrated by the following test examples. 3It has a bending strength of 25 to 100 MPa and a peel strength of 0.3 to 3.0 MPa, and can be suitably used as a substrate for directly adhering a decorative material such as sliced ​​veneer or decorative sheet onto it to make a decorative board. Regarding the density distribution of the wood shavings board, by using raw wood shavings with a moisture content of 15% by weight or less, it is possible to effectively prevent the formation of a high-density layer on the surface of the wood shavings board, and further, by adjusting the timing and pressure at which the hot platen is brought into contact with the wood shavings mat during hot pressing, it is possible to keep the density distribution at 0.3 to 0.95 g / m. 3 The density of the wood chipboard can be within the range of 0.1 to 1.0 μm, and a wood chipboard having a uniform density distribution can be produced.

[0024] The following test examples will explain the examples and comparative examples of the present invention. In these test examples, cypress logs were cut with a flaker to obtain sample A (mainly shavings of 0.1 to 0.6 mm thick, but also including wood powder and debris less than 0.1 mm thick that inevitably occurs when obtaining these thin shavings) with a thickness of 0.6 mm or less, and sample B with a thickness of 0.7 to 1.2 mm. The length and width of the shavings for samples A and B were the same, with a length of 10 to 200 mm and a width of 1 to 50 mm. These samples A and B were used to make raw wood shavings, with the weight blending ratio of sample A to the total weight (A+B) being changed in 9 ways: 80%, 70%, 68%, 66%, 64%, 62%, 60%, 50%, and 30%. An adhesive consisting of crude diphenylmethane-4,4'-diisocyanate was applied to these pieces using the spray method described above to form a mat, and then the pieces were dried at a temperature of 190°C and a surface pressure of 17 kg / cm. 2 The mixture was subjected to hot pressing for 9 minutes under the above conditions to obtain test specimens 1 to 9 each having a size of 300 mm x 300 mm x 12 mm thick.

[0025] For comparison, MDF, known for its excellent surface smoothness, and OSB made using conventional technology (using only sample B as the raw wood shavings) were used as comparative examples A to D. Comparative examples A and B are MDF that is actually commercially available as a floor base material, while comparative examples C and D are OSB that is actually commercially available as a structural panel. The dimensions of comparative examples A to D were 300 mm x 300 mm x 12 mm thick, the same as the test specimens.

[0026] The surface profile of each of these specimens 1 to 9 and comparative examples A to D (hereinafter collectively referred to as "specimens") was measured using a surface roughness measuring instrument (JIS B 0651:2001, Surftest SJ-310, manufactured by Mitutoyo Corporation). As shown in Figure 3, the specimen, with planar dimensions of 300 mm × 300 mm, was divided into nine 100 mm × 100 mm regions, and the centers of each region were designated as measurement points 1 to 9. Specifically, the measuring instrument was placed on the surface of each specimen, and the stylus attached to each measurement point automatically measured the uneven profile at 0.01 mm intervals as it moved along a 15 mm linear range. The uneven profile was measured by calculating the maximum height (JIS B 0601:2013, the distance from the bottom of the deepest recess to the apex of the highest protrusion, Rz = Rv + Rq) within this measurement range, and the average and maximum values ​​of the maximum heights measured at each measurement point are listed in Table 1.

[0027] [Table 1]

[0028] Furthermore, for each of these test specimens 1 to 9 and comparative examples A to D, the surface condition when a decorative sheet was directly applied thereon was visually evaluated, and the results are shown in Table 2. In this table, a circle indicates that the unevenness of the substrate surface was not visible on the decorative sheet surface, and a good surface condition was observed, and an X indicates that the unevenness of the substrate surface was visible on the decorative sheet surface, and a poor surface condition was observed.

[0029] [Table 2]

[0030] As can be seen from the results shown in Table 1, there is a tendency for the average and maximum values ​​of the maximum height Rz of the surface irregularities to decrease as the weight blending ratio of sample A increases. Specimens 1 to 9, which contain 30% or more sample A, all have smaller average and maximum values ​​of maximum height Rz than conventional OSB (Comparative Examples C and D: both have very large average and maximum values ​​of maximum height Rz, indicating significant surface irregularities). While this improves surface smoothness, specimens 4 to 9, which contain 66% or less sample A by weight, do not achieve values ​​comparable to those of MDF (Comparative Examples A and B). In contrast, specimens 1 to 3, which contain 68% or more sample A by weight, achieve surface smoothness similar to that of MDF (Specimens A and B). In particular, specimens 1 and 2, which contain 70% or more sample A by weight, achieve surface smoothness approximately equivalent to that of MDF (Comparative Examples A and B).

[0031] Furthermore, as can be seen from the results shown in Table 2, the surface condition of all of these specimens 1 to 3 was good when a decorative sheet was directly attached to them. These results demonstrate that wood flake boards manufactured with a weight blending ratio of sample A of 68% or more, more preferably 70% or more, are suitable for use as a base material for decorative boards in place of MDF.

[0032] In the above test example, the weight blending ratio of Sample A was set to a maximum of 80% (Specimen 1). Based on the results shown in Table 1, it is predicted that incorporating a larger amount of Sample A would result in smaller average and maximum values ​​of the maximum surface height Rz, resulting in a surface smoothness equal to or greater than that of MDF (Specimens A and B). It is predicted that incorporating 100% Sample A would achieve the maximum effect. However, producing wood shavings with a thickness of 0.1–0.6 mm is less productive and more costly than producing wood shavings with a thickness of 0.7 mm or greater, making it impractical to incorporate excessive amounts of Sample A. Furthermore, by incorporating a certain amount of Sample B, which is made of relatively thick wood shavings, the weight of Sample B serves to sink the entire mat, stabilizing it on the production line and preventing line stoppages due to tilting, collapse, or tipping. From these perspectives, it is preferable to keep the weight blending ratio of Sample A below 95%.

[0033] Furthermore, in the above test examples, as mentioned above, Sample A was prepared by mixing not only 0.1-0.6 mm thick wood shavings, but also wood powder and chips, etc., that are inevitably generated when obtaining these thin wood shavings, with a thickness of less than 0.1 mm. The shavings contained in Sample A can be obtained without the need for separation from the 0.1-0.6 mm thick wood shavings after obtaining them, which not only improves workability and cost benefits but also reduces raw material waste. Furthermore, by mixing the shavings into the raw wood shavings, the shavings penetrate into the gaps between the wood shavings during hot pressing and fill the gaps, thereby improving the surface smoothness of the resulting wood shavings board and contributing to various physical properties.

[0034] 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]

[0035] 1 Wood cut thin plate (base material) 2. Wood shavings less than 0.6 mm thick 3. Wood shavings over 0.6 mm thick 4. Cosmetic materials 5 Decorative panels

Claims

1. A shaved wood board obtained by cutting wood and mixing and aggregating shaved wood flakes of 10 to 200 mm in length, 1 to 50 mm in width, and 0.6 mm or less in thickness, and 10 to 200 mm in length, 1 to 50 mm in width, and more than 0.6 mm in thickness with adhesive, and then thermo-compressing the mixture together, wherein the shaved wood flakes are stacked one on top of the other, and the surface of the shaved wood board is formed by compressed shaved wood flakes, and the average maximum height indicating the surface roughness defined in Japanese Industrial Standard JIS B 0601:2013 is 40 μm or less, and the maximum value is 50 μm or less.

2. A method for producing a wood shavings board is characterized in that a first wood shavings group consisting of an aggregate of wood shavings having a thickness of 0.6 mm or less and a second wood shavings group consisting of an aggregate of wood shavings having a thickness of more than 0.6 mm are prepared, the first wood shavings group is mixed with the total amount of the first wood shavings group and the second wood shavings group at 68% by weight or more to form raw wood shavings, and an adhesive is applied to these raw wood shavings, mixed, accumulated, and thermocompressed together.

3. 3. The method for manufacturing a shaved wood board according to claim 2, wherein the first group of shavings includes shavings generated when obtaining the shavings.

4. A shaved wood board manufactured by the manufacturing method of claim 2 or 3.

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