Method for manufacturing wooden board

Abstract

The present disclosure addresses the problem of providing a method for manufacturing a wooden board, the method enabling manufacture of a wooden board having good quality. The present disclosure provides a method for manufacturing a wooden board using a plant biomass raw material or an intermediate material thereof. The method includes a sieving step for performing sieving on the basis of a correspondence relationship between a specific size and physical properties of a wooden board manufactured using a wooden element having the specific size.

Description

Wood board manufacturing method

[0001] The present disclosure relates generally to methods for manufacturing wood boards.

[0002] Patent Document 1 discloses a method for manufacturing a fiberboard. In this method, a wood material is steamed and defibrated to obtain wood fibers, to which an adhesive is added, and the board is then formed and thermo-compressed. In this case, the wood material includes a compressed material obtained by compressing and integrating dried pulverized materials of multiple palm family plants.

[0003] In Patent Document 1, it is believed that the fiber board is manufactured based on the empirical rule that the longer the wood fibers, the better.

[0004] However, the inventors have found that there are situations in which the above rule of thumb does not necessarily apply. Based on this finding, it is believed that it is possible to further improve the quality of wood boards.

[0005] International Publication No. 2022 / 080358

[0006] An object of the present disclosure is to provide a method for manufacturing a wood board that can produce a high-quality wood board.

[0007] A method for manufacturing a wood board according to one aspect of the present disclosure is a method for manufacturing a wood board using plant biomass raw materials or intermediate materials thereof, which includes a sieving step for sieving wood elements based on a correspondence between specific sizes and the physical properties of the wood board manufactured using the wood elements having the specific sizes.

[0008] Fig. 1 is a flowchart showing an example of a method for manufacturing a wood board (MDF) according to this embodiment. Fig. 2 is a flowchart showing another example of the method for manufacturing the same wood board (MDF). Fig. 3 is a flowchart showing another example of the method for manufacturing the same wood board (MDF). Fig. 4 is a flowchart showing an example of a method for manufacturing a wood board (particle board) according to this embodiment. Fig. 5 is a flowchart showing the manufacturing process of wood boards (fiber board and particle board).

[0009] 1. Overview The inventors of the present invention have conducted extensive research to obtain a wood board of higher quality than the fiber board of Patent Document 1, and as a result have developed the following method for manufacturing a wood board. Specifically, the method for manufacturing a wood board according to this embodiment is a method for manufacturing a wood board using plant biomass raw materials or intermediate materials thereof. The method for manufacturing a wood board includes a sieving step. The sieving step is a step of sieving based on the correspondence between specific sizes and the physical properties of a wood board manufactured using wood elements of the specific sizes (see Tables 1 and 2 below).

[0010] Here, when a fiberboard is manufactured as a wood board, "specific size" refers to a specific fiber length, more specifically, a certain range of sizes resulting from classification (for example, each classification fraction in Tables 1 and 2 described below). When a fiberboard is manufactured as a wood board, "wood elements" refers to defibrated fibers. When a particle board is manufactured as a wood board, "specific size" refers to the size of chips, more specifically, a certain range of sizes resulting from classification (each classification fraction). When a particle board is manufactured as a wood board, "wood elements" refers to chips. Furthermore, "physical properties" are not particularly limited, but examples thereof include mechanical properties. Mechanical properties are not particularly limited, but examples thereof include bending strength (Modulus of Rupture: MOR) and Young's modulus of elasticity (Modulus of Elasticity: MOE). Furthermore, "correspondence" can be considered the same as correlation.

[0011] The specific size may be the size of a wood element obtained by processing (defibrating, crushing, etc.) a plant biomass raw material or its intermediate material, or the size of the plant biomass raw material or its intermediate material itself.

[0012] In this embodiment, based on the above correspondence (see Tables 1 and 2 described below), sieving is performed in the sieving process so that the proportion of wood elements that contribute to high quality of the wood board is increased.

[0013] Therefore, according to this embodiment, it is possible to manufacture a high-quality wooden board. More specifically, it is possible to manufacture a wooden board having high strength and reduced variations in strength.

[0014] 2. Details The method for manufacturing a wood board according to this embodiment will now be described with reference to Figures 1 to 5. First, the wood board (types and materials) will be described, and then the method for manufacturing the wood board will be described.

[0015] (1) Wood Board (1.1) Types The wood board according to this embodiment is, for example, a fiberboard, a particleboard, etc. Fiberboard is classified into medium-density fiberboard, hardboard, and insulation board depending on the density, application, and manufacturing method.

[0016] Thus, in this embodiment, the wood board is medium density fiberboard (MDF), hardboard (HB), insulation board (IB), or particle board (PB). Hereinafter, abbreviations in parentheses may be used.

[0017] (1.2) Materials In this embodiment, plant biomass raw materials or intermediate materials thereof (described later) are used as the material for the wood board. Preferably, the plant biomass raw materials include at least one species selected from the group consisting of conifers, broad-leaved trees, and herbaceous plants. Herbaceous plants include palm, bamboo, rice straw, bagasse, etc. Specific examples of materials for the wood board include oil palm trunks (OPT), empty fruit bunches (EFB), and oil palm fronds (OPF). Plant biomass raw materials may also be raw wood logs, demolition materials, agricultural waste, etc.

[0018] (2) Manufacturing Method of Wood Board The manufacturing method of wood board will be explained separately for the manufacturing method of fiberboard and the manufacturing method of particleboard (see FIG. 5). In addition, since the manufacturing method of wood board includes a sieving process (see FIGS. 1 to 5), the sieving process will also be explained in a separate section. In FIG. 5, the manufacturing method of fiberboard includes three sieving processes from start to finish, but it is sufficient to include at least one sieving process. The same applies to the manufacturing method of particleboard.

[0019] <Method for Producing Fiberboard> The method for producing fiberboard will be further divided into the methods for producing MDF, HB, and IB and will be explained.

[0020] <<MDF Manufacturing Method>> Generally, MDF is manufactured through the steps of fiberizing the raw material (steaming and defibrating), drying, adding adhesives and water repellents, dry forming, heat pressing, humidity control, and finishing.

[0021] <<HB Manufacturing Method>> Generally, HB is manufactured through the steps of fiberizing the raw material (steaming and defibrating), adding water, adding a sizing agent, wet forming, heat pressing, humidity adjustment, and finishing.

[0022] <<Method for Producing IB>> Generally, IB is produced through the steps of fiberizing the raw material (steaming and defibrating), adding water, adding a sizing agent, wet forming, drying, adjusting the humidity, and finishing.

[0023] In particular, in the fiberboard manufacturing method of this embodiment, pretreatment is performed using a pretreatment means before the raw material is fiberized (steamed and defibrated) (see FIGS. 1 to 3 and 5). The pretreatment includes inputting production conditions, feeding raw material, and an intermediate material production process. In this way, the fiberboard manufacturing method has an intermediate material production process and a defibrating process. Note that the fiberization of raw material (steamed and defibrated) corresponds to the "defibrating (process)" in FIG. 5, dry forming corresponds to the "dry board process" in FIG. 5, and wet forming corresponds to the "wet board process" in FIG. 5.

[0024] Here, the pretreatment means in the fiberboard manufacturing method is not particularly limited, but examples thereof include a tablet press, a pelletizer, a briquette, a baler (roll, square), and the like.

[0025] Pretreatment using the above pretreatment means produces a pretreated product. Examples of pretreated products include, but are not limited to, tablets, pellets, briquettes, square bales, and roll bales. These are intermediate materials used in the production of fiberboard (see FIG. 5).

[0026] <PB Manufacturing Method> Generally, PB is manufactured through the steps of breaking down raw materials into small pieces (cutting and crushing), drying, adding adhesives and water repellents, dry forming, heat pressing, humidity adjustment, and finishing.

[0027] In particular, in the PB manufacturing method of this embodiment, pre-processing is performed using a pre-processing means before the raw material is broken down into small pieces (cutting and crushing) (see FIG. 5). The pre-processing includes inputting production conditions, adding raw material, and an intermediate material production process. In this way, the PB manufacturing method includes an intermediate material production process and a crushing process. The breaking down of raw material into small pieces (cutting and crushing) corresponds to the "crushing (process)" in FIG. 5, and dry forming corresponds to the "dry board process" in FIG. 5.

[0028] Here, the pretreatment means in the PB production method is not particularly limited, but examples thereof include a rotary race, a crusher, a classifier, a hammer mill, a ball mill, a ring flaker, a horizontal vibrating screen, a vertical vibrating screen, and a baler (roll, square).

[0029] Pretreatment using the above pretreatment means produces a pretreated product. Examples of pretreated products include, but are not limited to, veneers, crushed chips, classified chips, square bales, and roll bales. These are intermediate materials used in the production of PB (see FIG. 5).

[0030] <Sieving Step> The method for manufacturing a wood board according to this embodiment includes a sieving step.

[0031] That is, the method for manufacturing a fiberboard includes a sieving step (see FIGS. 1 to 3). In FIG. 3, the sieving step is a step before the intermediate material production step. In FIG. 2, the sieving step is a step between the intermediate material production step and the defibrating step. In FIG. 1, the sieving step is a step after the defibrating step. In FIG. 5, the method for manufacturing a fiberboard includes three sieving steps from start to finish, but it is sufficient to include at least one sieving step.

[0032] On the other hand, the manufacturing method of particle board also includes a sieving step (see FIG. 4). In FIG. 4, the sieving step is a step that follows the crushing step. In FIG. 4, the pre-treatment is omitted. In this way, the pre-treatment may be omitted in the manufacturing method of wood board. In FIG. 5, the manufacturing method of particle board includes three sieving steps from start to finish, but it is sufficient to include at least one sieving step.

[0033] The sieving process is a process of sieving based on the correspondence between specific sizes and the physical properties of a wood board manufactured using wood elements of specific sizes. Specifically, the sieving process sets optimal sieving conditions based on the correspondence in order to obtain desired physical properties, and is, for example, a process of sieving wood elements after a defibrating process or a crushing process, or a process of sieving wood elements before a defibrating process or a crushing process (see FIG. 5).

[0034] In the following, we will explain the case where a fiberboard is manufactured as a wood board. Therefore, "specific size" and "wood elements" will be referred to as "specific fiber length" and "defibrated fiber," respectively. Furthermore, "the correspondence between a specific size and the physical properties of a wood board manufactured using wood elements of a specific size" may be simplified to "the correspondence between a specific fiber length and the physical properties of the wood board."

[0035] <<Correspondence between specific fiber lengths and physical properties of wood boards>> A method for determining the correspondence between specific fiber lengths and physical properties of wood boards will be described using specific examples. However, the "correspondence between specific fiber lengths and physical properties of wood boards" in this embodiment is not limited to the following specific examples.

[0036] Table 1 shows an example of the correspondence between specific fiber lengths and the physical properties of wood boards.

[0037]

[0038] Bending strength evaluation (judgment) A: 25 MPa or more B: 20 ​​MPa or more and less than 25 MPa C: Less than 20 MPa.

[0039] Bending Young's modulus evaluation (judgment) A: 2.5 GPa or more B: 2.0 GPa or more and less than 2.5 GPa C: Less than 2.0 GPa.

[0040] The correspondence between the specific fiber lengths and the physical properties of the wood board shown in Table 1 can be created, for example, as follows.

[0041] The raw material is air-dried OPT chips, which are fed into a pelletizer to produce compressed pellets.

[0042] The compressed material is then pressure-defibrated in a pressure single-disc refiner to obtain defibrated fibers. The obtained defibrated fibers are classified using the same method as used to measure the size distribution of the chips contained in the compressed material, and the fiber length distribution of the defibrated fibers is determined from the total weight of the defibrated fibers in each classified fraction obtained.

[0043] Next, using only the fibers separated into each classification fraction, wood boards (target density 0.8 g / cm ３ Then, the bending strength and Young's modulus of bending of the obtained wood board are measured (see JIS A5905:2022).

[0044] The above results are summarized in Table 1. Table 1 shows the bending strength and bending Young's modulus of wood boards obtained using only each of the fibers "over 3.35 mm", "0.6-3.35 mm", "0.3-0.6 mm", and "under 0.3 mm".

[0045] Here, specific examples of the "specific fiber length" correspond to the OPT defibrated fiber classification fractions of "over 3.35 mm," "0.6-3.35 mm," "0.3-0.6 mm," and "under 0.3 mm" in Table 1. However, the "specific fiber length" (range of classification fractions and number of classification fractions) can be changed depending on the mesh size and number of sieves used.

[0046] From Table 1, it can be seen that among the four classification fractions of "over 3.35 mm," "0.6-3.35 mm," "0.3-0.6 mm," and "under 0.3 mm," "0.6-3.35 mm" has the best mechanical properties (flexural strength and bending Young's modulus). Thus, from Table 1, it can be seen that the empirical rule that the longer the fiber length, the better, is not necessarily valid.

[0047] Table 2 shows another example of the relationship between specific fiber lengths and the physical properties of wood boards. Table 2 was prepared in the same manner as Table 1, except that completely dry EFB chips were used as raw materials and sieves with openings of 1.0 mm, 0.85 mm, and 0.425 mm were used.

[0048]

[0049] The bending strength evaluation and bending Young's modulus evaluation in Table 2 are the same as those in Table 1.

[0050] From Table 2, it can be seen that among the four classification fractions of "over 1.0 mm," "0.85-1.0 mm," "0.425-0.85 mm," and "under 0.425 mm," "0.85-1.0 mm" is the most excellent in terms of mechanical properties (flexural strength and bending Young's modulus). Thus, from Table 2, it can be seen that the empirical rule that the longer the fiber length, the better, is not necessarily valid.

[0051] In the sieving process, sieving is performed based on the correspondence between specific fiber lengths and the physical properties of the wood board. Specifically, based on the correspondence shown in Table 1 or Table 2, sieving is performed to remove classified fractions that do not contribute to improving the quality of the wood board, and to increase the proportion of classified fractions that can contribute to improving the quality of the wood board. Here, classified fractions that do not contribute to improving the quality of the wood board refer, for example, to "under 0.3 mm" in Table 1 (because both the bending strength and the bending Young's modulus are C rank) and "under 0.425 mm" in Table 2 (because both the bending strength and the bending Young's modulus are C rank). On the other hand, classified fractions that can contribute to improving the quality of the wood board refer, for example, to "0.6-3.35 mm" in Table 1 (because both the bending strength and the bending Young's modulus are A rank) and "0.85-1.0 mm" in Table 2 (because the bending strength is A rank and the bending Young's modulus is B rank).

[0052] As described above, in the method for producing fiberboard, the sieving in the sieving step may be carried out after the defibrating step as shown in FIG. 1, or may be carried out as a pretreatment as shown in FIGS.

[0053] On the other hand, in the method for producing particle board, the sieving in the sieving step may be carried out after the crushing step as shown in FIG.

[0054] (3) Effects According to this embodiment, based on the correspondence between specific fiber lengths and the physical properties of the wood board (see Tables 1 and 2), the sieving process is performed to increase the proportion of wood elements that contribute to improving the quality of the wood board.

[0055] Therefore, according to this embodiment, it is possible to manufacture a high-quality wooden board. More specifically, it is possible to manufacture a wooden board having high strength and reduced variations in strength.

[0056] In this embodiment, the plant biomass raw material includes at least one species selected from the group consisting of coniferous trees, broad-leaved trees, and herbaceous plants. In this way, a wide range of tree species can be used as materials for the wood board.

[0057] In this embodiment, the wood board is a medium density fiberboard (MDF), a hardboard (HB), an insulation board (IB), or a particle board (PB). As such, there are a wide variety of applicable wood boards.

[0058] 3. Aspects As is apparent from the above embodiments, the present disclosure includes the following aspects.

[0059] The first aspect is a method for manufacturing a wood board using plant biomass raw materials or their intermediate materials, which includes a screening process in which screening is performed based on the correspondence between a specific size and the physical properties of a wood board manufactured using wood elements having said specific size.

[0060] According to this aspect, it is possible to manufacture a high-quality wooden board, more specifically, a wooden board having high strength and reduced variations in strength.

[0061] A second aspect is a method for producing a wood board based on the first aspect. In the second aspect, the plant biomass raw material includes at least one species selected from the group consisting of coniferous trees, broad-leaved trees, and herbaceous plants.

[0062] According to this embodiment, a wide range of tree species can be used as the material for the wood board.

[0063] A third aspect is a method for manufacturing a wood board based on the first or second aspect, in which the specific size is the size of a plant biomass material or an intermediate material thereof, or the size of a wood element obtained by processing the plant biomass material or the intermediate material thereof.

[0064] According to this embodiment, a wide variety of material forms can be applied.

[0065] A fourth aspect is a method for manufacturing a wood board based on any one of the first to third aspects. In the fourth aspect, the wood board is a medium density fiberboard, a hardboard, an insulation board, or a particle board.

[0066] According to this aspect, a wide variety of wood boards can be used.

[0067] A fifth aspect is a method for manufacturing a wood board based on any one of the first to third aspects. In the fifth aspect, the method for manufacturing a wood board further includes an intermediate material generating step and a defibrating step. The sieving step is at least one of a step before the intermediate material generating step, a step between the intermediate material generating step and the defibrating step, and a step after the defibrating step.

[0068] According to this embodiment, a high-quality wood board (fiberboard) can be manufactured.

[0069] A sixth aspect is a method for manufacturing a wood board based on any one of the first to third aspects. In the sixth aspect, the method for manufacturing a wood board further includes an intermediate material generating step and a crushing step. The sieving step is at least one of a step before the intermediate material generating step, a step between the intermediate material generating step and the crushing step, and a step after the crushing step.

[0070] According to this embodiment, a high-quality wood board (particle board) can be manufactured.

Claims

1. A method for manufacturing a wood board using plant biomass raw materials or intermediate materials thereof, comprising a screening step in which screening is performed based on the correspondence between a specific size and the physical properties of a wood board manufactured using wood elements having said specific size.

2. The method for manufacturing a wood board according to claim 1, wherein the plant biomass raw material includes at least one species selected from the group consisting of coniferous trees, broad-leaved trees, and herbaceous plants.

3. The method for manufacturing a wood board according to claim 1, wherein the specific size is the size of a plant biomass raw material or its intermediate material, or the size of a wood element obtained by processing the plant biomass raw material or its intermediate material.

4. The method for manufacturing a wood board according to claim 1, wherein the wood board is a medium density fiberboard, a hardboard, an insulation board, or a particle board.

5. A method for manufacturing a wood board according to any one of claims 1 to 3, further comprising an intermediate material production process and a defibrating process, and the sieving process is at least one of the following processes: a process before the intermediate material production process, a process between the intermediate material production process and the defibrating process, and a process after the defibrating process.

6. A method for manufacturing a wood board according to any one of claims 1 to 3, further comprising an intermediate material production step and a crushing step, and the sieving step is at least one of the steps preceding the intermediate material production step, between the intermediate material production step and the crushing step, and after the crushing step.

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