Wood-based board manufacturing method, and woody biomass compressed material

Abstract

The present disclosure addresses the problem of providing a wood-based board manufacturing method wherein physical properties of the wood-based board can be improved by suppressing pulverization and breaking of a woody biomass crushed material, and thus maintaining the size of the same, in a woody biomass compressed material. This wood-based board manufacturing method includes a supply step, a compression step, a forming step, and a molding step. In the supply step, the woody biomass crushed material and an adhesive component are mixed to obtain a first mixture that is a mixture of the woody biomass crushed material and the adhesive component. In the compression step, the first mixture is compressed while the adhesive component is cured or solidified to obtain a woody biomass compressed material. In the forming step, the woody biomass compressed material is broken down to obtain a woody element, and a mat-shaped molded material is obtained from the woody element. In the molding step, the mat-shaped molded material is molded while being heated or dried.

Description

Wood board manufacturing method and compressed wood biomass

[0001] The present disclosure relates generally to a method for manufacturing a wood board and a compressed wood biomass product, and more particularly to a method for manufacturing a wood board containing wood biomass and a compressed wood biomass product.

[0002] Patent Document 1 discloses a method for producing a fiberboard. This method involves steaming and defibrating a wood material to obtain wood fibers, adding an adhesive to the resulting fibers, and then forming and thermo-compressing the wood material. The wood material includes a compressed material obtained by compressing and integrating dried pulverized materials of multiple palm family plants.

[0003] However, the fiberboard manufacturing method of Patent Document 1 has a problem in that the wood fibers are easily pulverized and broken when the crushed palm plant material is compressed into pellets, resulting in a relatively small fiber size in the compressed product. The physical properties of a fiberboard generally depend on the fiber size of the compressed product. Therefore, when attempting to manufacture a fiberboard using such a compressed product, it is difficult to improve the physical properties of the fiberboard because the average length and average diameter of the compressed product are relatively small.

[0004] International Publication No. 2022 / 080358

[0005] An object of the present disclosure is to provide a method for manufacturing a wood board and a compressed wood biomass product that can improve the physical properties of the wood board by suppressing powdering and breaking of the pulverized wood biomass material in the compressed wood biomass product and maintaining its size.

[0006] A method for manufacturing a wood board according to one embodiment of the present disclosure includes a supplying step of mixing pulverized wood biomass with an adhesive component to obtain a first mixture, which is a mixture of the pulverized wood biomass and the adhesive component; a compressing step of compressing the first mixture while hardening or solidifying the adhesive component to obtain a compressed wood biomass product; a forming step of decomposing the compressed wood biomass product to obtain wood elements and obtaining a mat-like molded product from the wood elements; and a molding step of molding the mat-like molded product while heating or drying it.

[0007] A compressed wood biomass product according to one embodiment of the present disclosure is a compressed product obtained by compressing a mixture of pulverized wood biomass and a hardened or solidified adhesive component.

[0008] 1. Overview As described above, the fiberboard manufacturing method of Patent Document 1 has a problem in that the compressed product, which is the raw material for fiberboard, contains relatively small wood fibers. The inventors believe that the cause of this problem is as follows: In other words, the compressed product of Patent Document 1 is prone to pulverization and breakage because the pressure and the amount of wood fiber supplied are high when molding into pellets, and as a result, the wood fibers contained in the compressed product are relatively small.

[0009] Therefore, the inventors conducted extensive research to improve the strength of wood boards, and as a result, by making ingenious efforts to manufacture compressed wood biomass products, they developed the following method for manufacturing wood boards.

[0010] That is, the method for manufacturing a wood board according to this embodiment includes a supplying step, a compressing step, a forming step, and a molding step. In the supplying step, pulverized wood biomass and an adhesive component are mixed to obtain a first mixture, which is a mixture of pulverized wood biomass and the adhesive component. In the compressing step, the first mixture is compressed while the adhesive component is cured or solidified to obtain a compressed wood biomass product. In the compressing step, the adhesive component improves the adhesion between the pulverized wood biomass particles, thereby reducing the pressure during compression and the amount of pulverized wood biomass supplied, thereby reducing the likelihood of pulverization and breakage of the pulverized wood biomass particles in the compressed wood biomass product. In the forming step, the compressed wood biomass is decomposed to obtain wood elements, and a mat-like molded product is obtained from the wood elements. In the molding step, the mat-like molded product is molded while being heated or dried. This allows a wood board to be obtained.

[0011] Although the wood elements may become somewhat smaller through these processes, since a large amount of relatively large wood biomass pulverized material remains in the compressed wood biomass product, the wood board still contains relatively large wood elements even after these processes compared to when no adhesive component is added, thereby improving the strength of the wood board.

[0012] 2. Details The wood board according to this embodiment is not particularly limited, but includes, for example, insulation board, medium density fiberboard (MDF), hardboard, and particle board. The wood board is preferably medium density fiberboard.

[0013] The following embodiments are merely a portion of various embodiments of the present disclosure. Furthermore, the following embodiments can be modified in various ways depending on the design, etc., as long as the object of the present disclosure can be achieved. Furthermore, although the mechanism of action in the embodiments may be described, this description of the mechanism of action includes an explanation based on speculation, and the present disclosure is not bound by the description of the mechanism of action.

[0014] (First embodiment) A method for manufacturing a wood board according to the first embodiment will be described. The wood board according to the first embodiment is, for example, a medium-density fiberboard or an insulation board. The method for manufacturing a wood board according to the first embodiment includes a supplying process, a compressing process, a forming process, and a molding process. These processes will be described below in the order of the processes.

[0015] <Supplying Step> The supplying step is a step of mixing the pulverized wood biomass material (hereinafter sometimes simply referred to as "pulverized material") with the adhesive component to obtain a first mixture. The mixing method is not particularly limited, but examples include spraying using a sprayer or sprayer, immersion in a liquid adhesive component, direct application using a roller, and bead application using a nozzle or tube.

[0016] The pulverized material and adhesive component used in the supplying step will be described below.

[0017] <Pulverized Woody Biomass> Pulverized woody biomass is obtained by pulverizing woody biomass, which is a raw material, into small pieces.

[0018] Woody biomass is biomass made from wood-based materials. Biomass refers to renewable, organic resources derived from living organisms (excluding fossil fuels). Plants used for woody materials are broadly divided into woody plants (so-called trees) and herbaceous plants (so-called grasses), but they can be either woody or herbaceous. Specifically, woody biomass includes, for example, grasses, palms, hemp, bamboo, etc. Grass plants include, for example, sugarcane (bagasse). Palm plants include, for example, oil palm, borage palm, coconut palm, date palm, sago palm, acai, and palm. Hemp plants include, for example, kenaf and jute. Usable parts of palm plants include the trunk (OPT: Oil Palm Trunk), empty fruit bunch (EFB: Empty Fruit Bunch), leaves (OPF: Oil Palm Fronds), and stems.

[0019] The woody biomass is preferably a palm plant. It is particularly preferable to use oil palm. Oil palm is a type of palm tree planted in Malaysia, Indonesia, Thailand, Colombia, and other countries to obtain palm oil. Oil palm trunks are treated as an unused resource because they lack the strength required for construction materials. Furthermore, oil palm trunks have a high moisture content and contain sugars, making them prone to decay. Therefore, they are currently left to rot and disposed of, but the greenhouse gases generated during decay pose environmental concerns. From the above perspective, the use of oil palm can recycle unused resources and solve environmental problems.

[0020] The method for pulverizing woody biomass is not particularly limited, but examples thereof include a hammer mill, a cutter mill, a chipper, and a ball mill. The pulverization may be carried out once or twice or more times. The size of the pulverized material is not particularly limited.

[0021] The resulting pulverized material is preferably subjected to removal of foreign matter using a foreign matter remover. The foreign matter remover is not particularly limited, and any known foreign matter remover can be used.

[0022] The obtained pulverized material is preferably dried. The moisture content of the pulverized material is preferably 25% by mass or less, more preferably 20% by mass or less. In this case, the progression of decay of the pulverized material can be prevented, and the storage properties of the compressed wood biomass material for manufacturing wooden boards can be improved. The moisture content of the pulverized material can be determined by the total drying method. Drying may also be carried out before the pulverization step.

[0023] Here, woody biomass contains parenchyma tissue. Parenchyma tissue is tissue composed of parenchyma cells. Parenchyma tissue includes assimilation tissue, secretory tissue, storage tissue, etc., and has physiological functions such as synthesis, decomposition, and storage. The pulverized material mainly composed of parenchyma tissue is in the form of a fine powder and is smaller than pulverized materials mainly composed of vascular bundles. This pulverized material mainly composed of parenchyma tissue can cause a decrease in the strength of the wood board, variations in the quality of the wood board, poor drying, etc. Therefore, it is preferable to reduce the weight of the pulverized material mainly composed of parenchyma tissue from the woody biomass by classification. The classification method is not particularly limited, but examples include sieving, air sorting, water bathing, etc.

[0024] The length and diameter of the pulverized material after classification are preferably 0.8 mm to 50.0 mm in length and 0.10 mm to 2.00 mm in diameter (hereinafter, pulverized material after classification in this range may be referred to as "large-sized pulverized material"). When the length is 0.8 mm or more and the diameter is 0.10 mm or more, the strength of the wood board can be improved. When the length is 50.0 mm or less and the diameter is 2.00 mm or less, the deterioration of the surface smoothness of the wood board can be suppressed.

[0025] The length and diameter of the large-sized pulverized particles in the pulverized product can be measured as follows: For a predetermined amount of classified pulverized product, the length and diameter of each pulverized particle are measured using a magnifying glass, microscope, etc., and the arithmetic mean value of the results is calculated.

[0026] The content (mass ratio) of large-sized pulverized material relative to the total amount of pulverized material is preferably 70% by mass or more, more preferably 75% by mass or more. In this case, the strength of the wood board can be improved. The upper limit of the large-sized pulverized material content is not particularly limited, but is, for example, 100% by mass or less.

[0027] The content of large-sized pulverized material in the pulverized material after classification can be obtained by measuring the length and diameter of a predetermined amount of pulverized material after classification using a magnifying glass, microscope, etc., classifying it according to whether or not the length is between 0.8 mm and 50.0 mm and the diameter is between 0.10 mm and 2.00 mm, and then calculating the mass ratio of the material that falls within this range (large-sized pulverized material) to the material that does not fall within this range.

[0028] <Adhesive Component> The adhesive component is a component that bonds pulverized materials together. By improving the adhesiveness between pulverized materials, powdering and breaking of the pulverized materials in the compressed wood biomass product (hereinafter sometimes simply referred to as "compressed product") can be suppressed and the size can be maintained, thereby improving the strength of the wood board. In addition, since the pulverized materials are easily pressed together in the subsequent compression process, a compressed product can be formed without strong compression. Since a compressed product can be formed without strong compression, it is also possible to produce compressed products with low specific gravity that could not be produced in the past without compromising the mechanical durability of the compressed product. In addition, the adhesive component also acts as a binder, as described below, which can further improve the strength of the wood board.

[0029] The adhesive component is not particularly limited as long as it has adhesive properties. For example, the adhesive component preferably includes at least one selected from the group consisting of naturally occurring substances and fossil resource-derived substances. In this case, the adhesive properties between the pulverized materials and the mechanical durability of the compressed product can be improved.

[0030] Naturally occurring substances are not particularly limited, but examples thereof include proteins such as glue, gelatin, and casein; sugars such as starch, glucose, fructose, sucrose, and chitosan; acids having two or more carboxy groups such as citric acid, aspartic acid, glutamic acid, and malic acid; persimmon tannins; and natural rubber latex.

[0031] The fossil resource-derived substance is not particularly limited, but examples thereof include melamine resin, urea resin, phenol resin, vinyl acetate resin, epoxy resin, urethane resin, polyethylene glycol, polyvinyl alcohol, and aqueous polymeric isocyanate.

[0032] The adhesive component preferably contains at least one selected from the group consisting of starch and urea resin. In this case, the adhesive component is decomposed into smaller molecules during the steaming and defibration treatment described below, which improves the adhesiveness of the wood elements during the molding process and can increase the strength of the wood board.

[0033] The content of the adhesive component relative to the total mass (bone dry mass) of the pulverized material and the total mass of the adhesive component is preferably 0.1% by mass or more and 50% by mass or less, more preferably 1% by mass or more and 25% by mass or less, and even more preferably 3% by mass or more and 15% by mass or less. When the content is 0.1% by mass or more, the adhesiveness of the pulverized material is improved, powdering and breakage of the pulverized material are suppressed, and the strength of the wood board can be improved. When the content is 50% by mass or less, the shape of the compressed material is easily maintained, and a decrease in the mechanical durability of the compressed material can be suppressed.

[0034] <Compression Process> The compression process is a process for obtaining a compressed wood biomass product for a wooden board by compressing the first mixture while hardening or solidifying the adhesive component in the first mixture. As described above, because the first mixture contains the adhesive component, the pressure and amount of pulverized material supplied can be reduced compared to the manufacturing conditions for conventional compressed products. This prevents excessive pressure from being applied to the compressed product, suppresses pulverization and breakage of the pulverized material in the compressed product, and maintains its size, thereby improving the strength of the wood board manufactured using this compressed product. Furthermore, because the compressed product can be formed without strong compression, it is possible to produce compressed products with low specific gravity, which were previously not possible to produce, without compromising the mechanical durability of the compressed product.

[0035] To obtain a compressed product, for example, a tablet press, a pelletizer, etc. can be used. From the viewpoint of production efficiency, a pelletizer is preferred. The pelletizer is not particularly limited, but examples thereof include a flat die type and a ring die type.

[0036] The shape of the compressed product is not particularly limited, but may be, for example, a cylindrical shape. The size of the compressed product is not particularly limited, but in the case of a cylindrical shape, it may have an average length of 5 mm to 50 mm and an average diameter of 4 mm to 10 mm.

[0037] The specific gravity of the compressed product is preferably 0.1 or more, more preferably 0.3 or more, and even more preferably 0.6 or more. The specific gravity of the compressed product is preferably 1.3 or less, more preferably 1.1 or less, and even more preferably 0.9 or less. When the specific gravity is 0.1 or more, the mechanical durability of the compressed product is improved, and the compressed product is less likely to break or crack during transportation. When the specific gravity is 1.3 or less, the reduction in the length and diameter of the pulverized product is suppressed, and the strength of the wood board can be improved.

[0038] The moisture content of the compressed product is preferably 25% by mass or less, more preferably 20% by mass or less. In this case, the progression of decay of the compressed product can be prevented, and the storage stability of the compressed product can be improved. The moisture content of the compressed product can be determined by the total drying method.

[0039] The length and diameter of the pulverized material in the compressed product are preferably 0.6 mm to 40.0 mm in length and 0.08 mm to 1.60 mm in diameter (hereinafter, pulverized material in the compressed product within this range may be referred to as "good-sized pulverized material"). When the length is 0.6 mm or more and the diameter is 0.08 mm or more, the strength of the wood board can be improved. When the length is 40.0 mm or less and the diameter is 1.60 mm or less, the deterioration of the surface smoothness of the wood board can be suppressed.

[0040] The length and diameter of the pulverized particles in the compressed product can be measured as follows. First, a predetermined amount of the obtained compressed product is immersed in water and then stirred to obtain decomposition products of the compressed product. The length and diameter of each decomposition product are measured using a magnifying glass, microscope, etc., and the arithmetic mean value of the results is calculated.

[0041] The content (mass ratio) of the fine-sized pulverized material relative to the total amount of the compressed material is preferably 40% by mass or more, more preferably 55% by mass or more, and even more preferably 70% by mass or more. In this case, the strength of the wood board can be improved. The upper limit of the fine-sized pulverized material content is not particularly limited, but is, for example, 100% by mass or less.

[0042] The content of good-sized pulverized material in the compressed material can be obtained by measuring the length and diameter of a predetermined amount of compressed material using a magnifying glass, microscope, etc., classifying it according to whether or not the length is between 0.6 mm and 40.0 mm and the diameter is between 0.08 mm and 1.60 mm, and then calculating the mass ratio of the material that falls within this range (good-sized pulverized material) to the material that does not fall within this range.

[0043] <Forming process> The forming process is a process in which the compressed material is decomposed to obtain wood elements, a binder is added to the wood elements to obtain a second mixture, and the second mixture is layered and formed to obtain a mat-like molded product. Specifically, the decomposition method of the compressed material involves steaming and defibrating the compressed material to obtain wood fibers, which are the wood elements.

[0044] The steaming and defibrating process is a process in which the compressed material is softened by steaming and then decomposed into fibers or fiber bundles by defibrating. That is, by steaming the compressed material and defibrating it, wood fibers that are wood elements can be obtained.

[0045] Steaming involves treating the compressed material with high-temperature, high-pressure saturated steam. Steaming conditions are not particularly limited, but include, for example, a temperature of 150°C to 200°C, a pressure of 0.5 MPa to 2.0 MPa, and a time of 1 minute to 15 minutes. Steaming and defibration can be performed using a known steaming and defibration device, such as a pressurized refiner.

[0046] After the steaming and defibration treatment, drying may be carried out as needed. Drying is a treatment to reduce the moisture content of the defibrated wood fibers. Drying can be carried out by supplying hot air to the defibrated wood fibers.

[0047] The moisture content of the dried wood fibers is not particularly limited, but is, for example, 20% by mass or less of the total amount of bone-dried wood fibers. The drying can be performed at any time before or after the binder addition process described below. That is, the drying can be performed after adding the binder to the wood fibers, before adding the binder to the wood fibers, while adding the binder to the wood fibers, or by adding the binder to the wood fibers, drying the fibers, and then adding the binder again.

[0048] The binder added to the wood elements hardens or solidifies to bond the wood elements together. The binder is preferably a thermosetting resin, more preferably diphenylmethane diisocyanate (MDI), urea resin, urea-melamine co-condensation resin, or phenolic resin. A water repellent may also be added to the binder.

[0049] The amount of binder added relative to the total mass of the wood elements and binder is not particularly limited, but is, for example, 1 mass % or more and 10 mass % or less.

[0050] The wood elements to which the binder has been added are then stacked and formed into a mat-like molded product, which can be obtained using a known gravity former or suction former.

[0051] <Molding Step> In the molding step, the formed mat-like product is heated to harden or solidify the added binder, thereby forming a wooden board.

[0052] In the molding process, the mat-shaped product is pressed while being heated. A known hot press can be used for pressing. A distance bar (thickness gauge) may be attached between the hot plates of the hot press. The distance bar can ensure that the thickness of the wood board is constant.

[0053] The heating temperature is not particularly limited, but is, for example, 140° C. to 230° C. The pressure during pressing is not particularly limited, but is, for example, 0.5 MPa to 10 MPa. The heat-pressing time is not particularly limited, but is, for example, 10 seconds to 3 minutes.

[0054] In this manner, the wood board according to this embodiment can be obtained. The thickness of the wood board is not particularly limited, but is, for example, 20 mm or less.

[0055] Second Embodiment A method for manufacturing a wood board according to a second embodiment will be described. The wood board according to the second embodiment is, for example, a particle board. Note that the description of the same configuration as in the first embodiment will be omitted as appropriate.

[0056] The manufacturing method of the wood board according to the second embodiment differs from the manufacturing method of the wood board according to the first embodiment in that a suitable adhesive component is used in the supplying step, and that small wood pieces are obtained as wood elements by cutting or crushing the compressed material in the forming step. That is, the compressing step and molding step are the same as those of the first embodiment.

[0057] The adhesive component according to the second embodiment preferably contains at least one selected from the group consisting of urea resin and melamine resin. In this case, the adhesive component is thermally cured during the molding process, which can improve the strength of the wood board.

[0058] In the second embodiment, in the forming process, wood chips that are wood elements are obtained from the compressed material by cutting or crushing. Cutting or crushing is a process of breaking down the compressed material by applying shear. For cutting or crushing, known devices can be used, such as crushers such as hammer mills, drum flakers, and ring flakers, cutting machines, and dry fiberizers.

[0059] Third Embodiment A method for manufacturing a wood board according to a third embodiment will be described. The wood board according to the third embodiment is, for example, a hardboard or an insulation board. Note that the description of the same configuration as in the first or second embodiment will be omitted as appropriate.

[0060] The manufacturing method of the wood board according to the third embodiment differs from that of the first embodiment in that a suitable adhesive component is used in the supplying step, and that a mat-like molded product is obtained by forming using a wet papermaking method in the forming step. That is, the compression step and molding step are the same as those of the first embodiment.

[0061] The adhesive component according to the third embodiment preferably contains at least one selected from the group consisting of urea resin, starch, sucrose, and citric acid. These adhesive components are water-soluble and dissolve in water during the wet papermaking process described below. They are dispersed uniformly in the mat-like molding, thereby acting as a binder, improving the strength of the wood board and suppressing quality variations.

[0062] In the third embodiment, a mat-like molded product is obtained by a wet papermaking process in the forming step. The wet papermaking process involves dispersing wood fibers as wood elements in water, forming the material into a paper using a papermaking machine, and then compressing and dehydrating the material while adjusting the thickness, shape, etc. using a roll press to obtain a mat-like molded product. Papermaking refers to the process of uniformly dispersing and mixing materials in water, which is known as papermaking. Well-known devices can be used for the wet papermaking process, such as a cylinder papermaking machine or a Fourdrinier papermaking machine.

[0063] The binder used in the wet papermaking method can be any of those described in the first embodiment, but a water-soluble binder is more preferable. A sizing agent may be added in addition to the binder. The binder may be added when dispersing the wood elements in water, when papermaking is performed using a papermaking machine, when compressing and dehydrating the wood elements using a roll press, or after the roll press.

[0064] (Fourth embodiment) A method for manufacturing a wood board according to the fourth embodiment will be described. The wood board according to the fourth embodiment is, for example, a hardboard or an insulation board. Note that the description of the same configuration as in the first to third embodiments will be omitted as appropriate.

[0065] The manufacturing method of the wood board according to the fourth embodiment differs from that of the third embodiment in that wood fibers are obtained as wood elements by cutting or crushing the compressed material in the forming process. That is, the supplying process, compressing process, and molding process are the same as those of the third embodiment.

[0066] In the fourth embodiment, wood fibers, which are wood elements, are obtained from the compressed product by cutting or crushing in the forming process. The same equipment as that used in the cutting or crushing process of the second embodiment can be used for cutting or crushing.

[0067] Fifth Embodiment A method for manufacturing a wood board according to a fifth embodiment will be described. The wood board according to the fifth embodiment is, for example, an insulation board. Note that the description of the same configuration as in the first to fourth embodiments will be omitted as appropriate.

[0068] The manufacturing method for a wood board according to the fifth embodiment differs from the third or fourth embodiment in that the mat-like product is dried in the molding process and then molded into a wood board. That is, the supplying process, compressing process, and forming process are the same as those of the third or fourth embodiment. Note that the wood fibers that are the wood elements in the forming process can be obtained by steaming and defibrating, crushing, or cutting.

[0069] In the molding step, the mat-like molded product obtained by the wet papermaking method is dried to form a wood board. Drying may be performed by supplying hot air or the like, by compressing without heating, or by leaving at room temperature. For drying, known devices can be used, such as a jet dryer, a steam dryer, a high-frequency dryer, a combined steam and high-frequency dryer, or an oven.

[0070] 3. Aspects As is apparent from the above embodiments, the present disclosure includes the following aspects.

[0071] The first aspect is a method for manufacturing a wood board, including a supplying step, a compressing step, a forming step, and a molding step. In the supplying step, pulverized wood biomass and an adhesive component are mixed to obtain a first mixture, which is a mixture of the pulverized wood biomass and the adhesive component. In the compressing step, the first mixture is compressed while the adhesive component is cured or solidified to obtain a compressed wood biomass product. In the forming step, the compressed wood biomass product is decomposed to obtain wood elements, and a mat-like molded product is obtained from the wood elements. In the molding step, the mat-like molded product is molded while being heated or dried.

[0072] According to this aspect, the physical properties of the wood board can be improved by suppressing pulverization and breakage of the pulverized wood biomass in the compressed wood biomass product and maintaining its size. In addition, the mechanical durability of the compressed wood biomass product can be improved and the reduction in the length and diameter of the pulverized wood biomass product can be suppressed, thereby improving the physical properties of the wood board.

[0073] A second aspect is a method for manufacturing a wood board based on the first aspect. In the second aspect, the specific gravity of the compressed product is 0.1 or more and 1.3 or less.

[0074] According to this aspect, the mechanical durability of the compressed wood biomass material is improved, making it less likely to break or crack during transportation. In addition, the reduction in the length and diameter of the pulverized wood biomass material is suppressed, improving the physical properties of the wood board.

[0075] A third aspect is a method for manufacturing a wood board according to the first or second aspect. In the third aspect, the forming step includes a step of obtaining wood fibers, which are wood elements, by steaming and defibrating the compressed wood biomass.

[0076] According to this aspect, wood fibers can be obtained as wood elements for obtaining a wood board.

[0077] A fourth aspect is a method for manufacturing a wood board based on the first or second aspect. In the fourth aspect, the forming step includes a step of cutting or crushing the compressed wood biomass material to obtain wood chips that are wood elements.

[0078] According to this aspect, small wood pieces can be obtained as wood elements for obtaining a wood board.

[0079] A fifth aspect is a method for manufacturing a wood board based on any one of aspects 1 to 4. In the fifth aspect, the forming step includes a step of mixing wood elements and a thermosetting resin to obtain a second mixture of the wood elements and the thermosetting resin, and a step of stacking the second mixture to obtain the mat-like molding.

[0080] According to this embodiment, a mat-like molding for obtaining a wood board can be obtained by a dry method.

[0081] A sixth aspect is a method for manufacturing a wood board according to the first or second aspect. In the sixth aspect, the forming step includes a step of cutting or crushing the compressed wood biomass material to obtain wood fibers, which are wood elements.

[0082] According to this aspect, wood fibers can be obtained as wood elements for obtaining a wood board.

[0083] A seventh aspect is a method for manufacturing a wood board according to any one of the first, second, third, and sixth aspects. In the seventh aspect, the forming step includes a step of forming the wood elements into a mat-like molding in water.

[0084] According to this embodiment, a mat-like molding for producing a wood board can be obtained by a wet method.

[0085] An eighth aspect is a method for producing a wood board based on any one of the first to seventh aspects. In the eighth aspect, the pulverized wood biomass contains pulverized material from a palm plant.

[0086] According to this aspect, palm plants can be effectively utilized.

[0087] A ninth aspect is a method for producing a wood board based on any one of the first to eighth aspects. In the ninth aspect, the adhesive component includes at least one selected from the group consisting of naturally occurring substances and fossil resource-derived substances.

[0088] According to this aspect, the adhesiveness between the pulverized wood biomass materials is improved, which prevents the pulverization and breaking of the pulverized wood biomass materials in the compressed wood biomass material, thereby maintaining their size and further improving the physical properties of the wood board.

[0089] A tenth aspect is a method for producing a wood board based on any one of the first, second, third, and fifth aspects. In the tenth aspect, the adhesive component includes at least one selected from the group consisting of starch and urea resin.

[0090] According to this embodiment, the adhesive components are broken down into smaller molecules during the steaming and defibration process, which improves the adhesion between the pulverized wood biomass materials during the molding process, thereby further improving the physical properties of the wood board.

[0091] An eleventh aspect is a method for producing a wood board according to any one of the first, second, fourth, and fifth aspects. In the eleventh aspect, the adhesive component includes at least one selected from the group consisting of urea resin and melamine resin.

[0092] According to this embodiment, the adhesive component is thermally cured by heating during the molding process, thereby further improving the physical properties of the wood board.

[0093] A twelfth aspect is a method for producing a wood board based on any one of the first, second, third, sixth, and seventh aspects. In the twelfth aspect, the adhesive component includes at least one selected from the group consisting of urea resin, starch, sucrose, and citric acid.

[0094] According to this embodiment, the adhesive component dissolves in water and is uniformly dispersed in the mat-like molding, which further improves the physical properties of the wood board and further reduces quality variations.

[0095] A thirteenth aspect is a compressed wood biomass product, which is a compressed product obtained by compressing a mixture of pulverized wood biomass and a hardened or solidified adhesive component.

[0096] According to this embodiment, it is possible to obtain a compressed wood biomass material that can improve the physical properties of the wood board, since the mechanical durability is improved and the decrease in the length and diameter of the pulverized material is suppressed.

[0097] The present disclosure will be specifically described below using examples, but the present disclosure is not limited to the following examples.

[0098] (Example) As shown in Table 1, oil palm trunks (OPT) were extracted as wood biomass, the raw material for wood boards, and then placed in a chipper to obtain 30 mm to 40 mm square wood biomass pulverized material. Next, foreign matter was removed using a foreign matter remover, and the material was placed in a wet grinder and re-pulverized, and then dried to a predetermined moisture content using a rotary kiln. The material was then sieved through an 8.6 mesh sieve and further sieved through a 50 mesh sieve to reduce the proportion of palm plant parenchyma tissue, resulting in a pulverized material with an average length of 25.0 mm and an average diameter of 1.10 mm. The pulverized material after classification contained 80% by mass of pulverized material with a length of 0.8 mm to 50.0 mm and a diameter of 0.10 mm to 2.00 mm (large-sized pulverized material).

[0099] Urea resin (manufactured by Oshika Corporation, product name: Oshika Resin (registered trademark) LS-12A) diluted with water as an adhesive component was uniformly added to the entire classified pulverized material using a spray gun to obtain a first mixture. The content of the added adhesive component was 10% by mass based on the total mass (bone dry mass) of the classified pulverized material and the total mass of the adhesive component. The obtained first mixture was compressed using a pelletizer into cylindrical pellets with an average length of 40 mm and an average diameter of 8 mm, yielding a woody biomass compressed product with a specific gravity of 0.65 and a moisture content of 8% by mass. Next, a predetermined amount of the obtained compressed product was immersed in water and stirred to decompose the compressed product. This decomposed product contained pulverized material with an average length of 13.8 mm and an average diameter of 0.82 mm. Furthermore, the decomposition products contained 72% by mass of pulverized material having a length of 0.6 mm or more and 40.0 mm or less and a diameter of 0.08 mm or more and 1.60 mm or less (good-sized pulverized material).

[0100] This compressed material was placed in a pressure refiner, steamed at 170°C for 5 minutes, defibrated, and dried in a jet dryer at 180°C to obtain dried fiber (wood fiber). Diphenylmethane diisocyanate (MDI) was dispersed and applied to this dried fiber as a binder at 3% by mass, and then compressed at 200°C for 90 seconds to produce a fiber with a thickness of 3 mm and a density of 800 kg / m. ３ I got a wooden board.

[0101] (Comparative Example) A wood board was obtained in the same manner as in the Example, except that no adhesive component was used when producing the pellet-shaped compressed wood biomass product, and the specific gravity of the compressed wood biomass product was set to 1.10. The load during compression was the same for both the Example and the Comparative Example. In this case, the crushed product after classification in the Comparative Example was less likely to form pellets than the first mixture in the Example, and the amount of crushed product after classification supplied to form pellets was greater than the amount of the first mixture in the Example, resulting in a higher specific gravity. In addition, the compressed wood biomass product was produced using raw materials from the same lot as those used in the Example.

[0102] <Evaluation Method> The evaluation methods and evaluation criteria for each evaluation item for the compressed product and wood board are explained below. Regarding the evaluation criteria, C means that the target is not achieved, B means that the result is satisfactory, and A means that the result is more satisfactory.

[0103] <<Mechanical Durability of Compressed Wood Biomass>> The mechanical durability (DU) of the compressed wood biomass after molding was measured based on the wood pellet quality standard of the Japan Wood Pellet Association. This test evaluates the resistance of the compressed material to pulverization due to mechanical impact, and evaluates the ratio of the mass of the compressed material after removing the pulverized compressed material due to mechanical impact using a sieve with a circular hole diameter (nominal mesh size) of 3.15 mm to the mass of the compressed material before the test.

[0104] DU = (m1 / m0) x 100 (%) m0: mass of the compressed product before the test m1: mass of the compressed product after the test

[0105] (Judgment) A: 97.5% or more B: 96.5% or more but less than 97.5% C: Less than 96.5%.

[0106] <Storage Properties of Compressed Woody Biomass> The mold resistance of compressed woody biomass was measured based on "JIS Z 2911 Mold Resistance Test Method." This test evaluates the number of days until mold appears on the compressed woody biomass. If mold does not appear after 14 days, the compressed woody biomass is judged to have a shelf life of 14 days or more.

[0107] (Judgment) A: 14 days or more B: 10 days or more but less than 14 days C: Less than 10 days.

[0108] <Strength of Wood Board> A bending test was carried out on the wood board based on "JIS A 5905 Fiberboard" to measure the bending strength.

[0109] (Judgment) A: 25 MPa or more B: 20 ​​MPa or more but less than 25 MPa C: Less than 20 MPa.

[0110] <Surface Smoothness of Wood Board> The center line average roughness Ra of the wood board was measured in accordance with "JIS B 0601 Surface Roughness."

[0111] A: 5 μm or less B: More than 5 μm and 15 μm or less C: More than 15 μm.

[0112]

[0113]

[0114] As shown in Table 1, the properties of the pulverized material after classification were almost the same, but the average length and average diameter of the decomposed material of the compressed material were larger in the Examples than in the Comparative Examples, and the good size content was better in the Examples than in the Comparative Examples. In other words, the powdering and breaking of the pulverized material was suppressed in the Examples compared to the Comparative Examples, confirming that adding an adhesive component to the pulverized material was effective.

[0115] Furthermore, with regard to the strength of the wood boards made using the compressed material, the comparative example was rated C and did not achieve the target, whereas the example was rated A, which was a more favorable result, confirming that a good size content of 40% by mass or more is effective.

Claims

1. A method for manufacturing a wood board, comprising: a supplying step of mixing pulverized wood biomass with an adhesive component to obtain a first mixture, which is a mixture of the pulverized wood biomass and the adhesive component; a compressing step of compressing the first mixture while hardening or solidifying the adhesive component to obtain a compressed wood biomass product; a forming step of decomposing the compressed wood biomass product to obtain wood elements and obtaining a mat-like molded product from the wood elements; and a molding step of molding the mat-like molded product while heating or drying it.

2. The method for manufacturing a wood board according to claim 1, wherein the specific gravity of the compressed wood biomass material is 0.1 or more and 1.3 or less.

3. A method for manufacturing a wood board according to claim 1 or 2, wherein the forming process includes a step of obtaining wood fibers, which are the wood elements, by steaming and defibrating the compressed wood biomass material.

4. A method for manufacturing a wood board according to claim 1 or 2, wherein the forming process includes a step of cutting or crushing the compressed wood biomass material to obtain wood chips that are the wood elements.

5. A method for manufacturing a wood board according to any one of claims 1 to 4, wherein the forming process includes a step of mixing the wood elements with a thermosetting resin to obtain a second mixture which is a mixture of the wood elements and the thermosetting resin, and stacking the second mixture to obtain the mat-like molding.

6. A method for manufacturing a wood board according to claim 1 or 2, wherein the forming process includes a step of cutting or crushing the compressed wood biomass material to obtain wood fibers that are the wood elements.

7. A method for manufacturing a wood board according to any one of claims 1, 2, 3 and 6, wherein the forming step comprises a step of forming the wood elements into paper in water to obtain the mat-like molding.

8. A method for manufacturing a wood board according to any one of claims 1 to 7, wherein the pulverized wood biomass contains pulverized palm plants.

9. A method for manufacturing a wood board according to any one of claims 1 to 8, wherein the adhesive component comprises at least one selected from the group consisting of naturally occurring substances and substances derived from fossil resources.

10. A method for manufacturing a wood board according to any one of claims 1, 2, 3 and 5, wherein the adhesive component comprises at least one selected from the group consisting of starch and urea resin.

11. A method for manufacturing a wood board according to any one of claims 1, 2, 4 and 5, wherein the adhesive component comprises at least one selected from the group consisting of urea resin and melamine resin.

12. A method for manufacturing a wood board according to any one of claims 1, 2, 3, 6 and 7, wherein the adhesive component comprises at least one selected from the group consisting of urea resin, starch, sucrose and citric acid.

13. A compressed wood biomass product, which is a compressed product obtained by compressing a mixture of ground wood biomass and a hardened or solidified adhesive component.

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