Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
  • B27N—MANUFACTURE BY DRY PROCESSES OF ARTICLES, WITH OR WITHOUT ORGANIC BINDING AGENTS, MADE FROM PARTICLES OR FIBRES CONSISTING OF WOOD OR OTHER LIGNOCELLULOSIC OR LIKE ORGANIC MATERIAL
  • B27N3/00—Manufacture of substantially flat articles, e.g. boards, from particles or fibres
  • B27N3/02—Manufacture of substantially flat articles, e.g. boards, from particles or fibres from particles
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
  • B27N—MANUFACTURE BY DRY PROCESSES OF ARTICLES, WITH OR WITHOUT ORGANIC BINDING AGENTS, MADE FROM PARTICLES OR FIBRES CONSISTING OF WOOD OR OTHER LIGNOCELLULOSIC OR LIKE ORGANIC MATERIAL
  • B27N3/00—Manufacture of substantially flat articles, e.g. boards, from particles or fibres
  • B27N3/06—Making particle boards or fibreboards, with preformed covering layers, the particles or fibres being compressed with the layers to a board in one single pressing operation

Definitions

• the present invention relates to particle board and a method for manufacturing particle board.
• Patent Document 1 discloses that particleboard, which is made by applying adhesive to crushed wood chips, piling them into a mat-like shape and hot pressing them with a hot platen, can be used as an alternative to plywood.
• Particleboard can be made from waste materials and recycled materials, and by changing the size of the crushed wood chips used in the core layer and surface layer, wood can be used without waste, making it an excellent alternative to plywood in that it can be made relatively inexpensively.
• the present invention involves incorporating numerous extremely thin wood shavings into a single layer of particleboard.
• the first invention is based on a particle board made up of a large number of wood pieces glued together in a collective state.
• the first invention is characterized in that the numerous wood pieces are a mixture of numerous crushed wood pieces and numerous thin wood cutting pieces having a uniform thickness of 0.05 mm or more and 0.35 mm or less.
• the particle board is made of a large number of wood pieces that are a mixture of a large number of wood crushed pieces and a large number of wood cutting pieces that have an extremely thin and uniform thickness of 0.05 mm to 0.35 mm by cutting.
• the bending strength of the particle board is increased. Therefore, it is not necessary to increase the density of the wood pieces or use a large amount of adhesive to ensure the bending strength of the particle board.
• the particleboard of the first invention when relatively coarse wood crushed pieces are used, if some of them are replaced with wood cutting pieces having a uniform thickness thinner than the wood crushed pieces, a large number of wood cutting pieces thinner than the wood crushed pieces before replacement will be included evenly.
• wood cutting pieces have a uniform thickness and a flat surface
• the total surface area of the many wood pieces that make up the particleboard increases significantly and homogenization is achieved.
• relatively fine wood crushed pieces if some of them are replaced with wood cutting pieces having a uniform thickness and a flat surface, the total surface area of the many wood pieces that make up the particleboard will increase significantly.
• the particleboard of the first invention is more resistant to moisture penetration and has excellent water resistance compared to conventional particleboards made only of ground wood chips.
• the crushed wood chips which are not cut to a thin thickness, are crushed during press molding, and when moisture penetrates the interior, the crushed wood chips absorb the moisture and tend to swell, which can cause significant changes in dimensions (changes in length and thickness).
• the particle board of the first invention as described above, has a structure that makes it more difficult for moisture to penetrate into the interior than conventional particle boards, and because the many replaced wood cutting pieces are cut to a thin thickness, there is no significant change in dimensions (length and thickness) due to moisture absorption.
• the inventors of the present application conducted a test to verify the effect of including extremely thin flake-like wood chips with a thickness of 0.05 mm to 0.35 mm in particleboard.
• particleboards including wood chips have improved bending strength (MOR), water absorption length change rate (LE), moisture absorption and release length change rate (HLE), and wood screw retention strength (WS) compared to conventional particleboards that do not include wood chips.
• MOR bending strength
• LE water absorption length change rate
• HLE moisture absorption and release length change rate
• WS wood screw retention strength
• TS water absorption thickness expansion rate
• the first invention it is possible to provide a particle board that has excellent surface properties, bending strength, screw pull-out strength, and water resistance, and has little dimensional change, without increasing cost or weight.
• the second invention is characterized in that in the first invention, the ground wood chips are first wood chips that pass through a first sieve with a mesh size of 16 mm or less and do not pass through a second sieve with a mesh size of 0.5 mm or more and smaller than the first sieve, or second wood chips that pass through both the first and second sieves.
• a large number of first wood chips that pass through a first sieve with a mesh size of 16 mm or less but do not pass through a second sieve with a mesh size of 0.5 mm or more and smaller than the first sieve, or fine second wood chips that pass through both the first and second sieves, are used as the ground wood pieces.
• a large number of thin wood cutting pieces of uniform thickness in such a large number of ground wood pieces it is possible to provide a particle board that has excellent surface properties, bending strength, screw pull-out strength, and water resistance, and has little dimensional change, without increasing cost or weight.
• the third invention is the first or second invention, characterized in that the wood cutting pieces are mixed in a ratio of 20% by weight to 90% by weight of the total weight of the numerous wood pieces.
• the inventors of the present application have found from the results of the above verification tests that by mixing multiple wood chips with wood cuttings in a ratio of 20% by weight to 90% by weight of the total weight of the wood chips, the normal bending strength (MOR), water absorption length change (LE), moisture absorption and release length change (HLE) and wood screw holding strength (WS) are improved, and that the higher the mixing ratio of wood cuttings, the greater the improvement rates of normal bending strength (MOR), water absorption length change (LE) and moisture absorption and release length change (HLE).
• MOR normal bending strength
• LE water absorption length change
• HLE moisture absorption and release length change
• WS wood screw holding strength
• wood chips are mixed into a large number of wood pieces in a ratio of 20% to 90% by weight of the total weight of the wood chips.
• the fourth invention is a method for manufacturing a particle board in which a large number of wood pieces are glued together in a collective state, comprising: a first crushing step of crushing a first wood material to produce a large number of wood chips; a first selection step of selecting at least one type of the large number of first to third wood chips obtained by a first classification step of classifying the large number of wood chips and the large number of wood chips using a first sieve with a mesh size of 16 mm or less and a second sieve with a mesh size of 0.5 mm or more and smaller than the first sieve, as a large number of crushed wood pieces; a cutting step of cutting the second wood material so that the fibers are linearly exposed on the surface to produce a large number of thin-flaky wood flakes having a uniform thickness of 0.05 mm to 0.35 mm; and a cutting step of cutting the large number of wood flakes and the large number of wood flakes so as to split them along the fiber direction.
• the method includes a second selection process for selecting at least one of the many small wood flakes having an elongated shape produced by the second crushing process, which crushes the wood into thin pieces, and the many first to third small wood flakes obtained by the second classification process, which classifies the many small wood flakes using a third sieve and a fourth sieve smaller than the third sieve, as many wood cutting pieces; a wood cutting mixing process for mixing the many crushed wood flakes and the many wood cutting pieces to produce the many wood pieces; an adhesive application process for applying an adhesive to the many wood pieces; a mat forming process for piling up the many adhesive-applied wood pieces to form a mat; and a hot pressing process for forming the particle board by applying a hot pressing process to the mat to harden the adhesive of the mat.
• crushing the first wood material means using a known crushing device to crush the first wood material finely until it passes through a sieve with a specified mesh size installed at the outlet of the crushing device, and wood chips of various shapes with non-uniform thickness are formed by crushing.
• cutting the second wood material means cutting the second wood material thinly and uniformly by a known cutting device having a blade that cuts material thinly and uniformly, and thin flake-like wood cutting pieces with uniform thickness are formed by cutting.
• wood cutting pieces with uniform thickness means that thickness variations due to processing errors are allowed, for example, thickness variations of about ⁇ 20% are allowed.
• the fifth invention is the fourth invention, characterized in that the cutting process, the second crushing process, and the second classification process are included in a manufacturing method for a wood board in which the numerous first small wood flakes are glued together in a collective state.
• the seventh invention is the fifth invention, characterized in that in the second selection process, the second small wood flakes that pass through both the third and fourth sieves and the third small wood flakes that do not pass through both the third and fourth sieves are selected as the numerous wood cutting pieces.
• wood chips other than the first small wood chips that are selected by classifying the small wood chips are used as the wood chips.
• waste wood that is generated during the formation of other wood boards and is not used for other wood boards is used as the wood chips that make up the particle board, making it possible to form particle boards more inexpensively.
• the second wood material of the other wood boards is used without waste, this leads to effective use of wood resources.
• the eighth invention is any one of the fourth to seventh inventions, characterized in that in the wood chip mixing process, the numerous crushed wood chips and the numerous wood chips are mixed so that the numerous wood chips make up 20% by weight or more and 90% by weight or less of the total weight of the numerous wood chips.
• wood chips are mixed with the numerous wood chips that make up the particle board in a ratio of 20% by weight to 90% by weight of the total weight of the numerous wood chips that make up the particle board.
• a single-layer particle board is made to contain numerous thin, uniformly-thick shaved wood chips, making it possible to provide a particle board with excellent surface properties, bending strength, screw pull-out strength and water resistance, and with little dimensional change, without increasing cost or weight.
• FIG. 1 is a cross-sectional view showing a part of a particle board according to a first embodiment.
• FIG. 2 is a diagram showing the process of producing ground wood pieces.
• FIG. 3 is a diagram showing the process of producing wood cutting pieces.
• FIG. 4 is an enlarged perspective view showing a first small wood piece.
• FIG. 5 is a diagram showing the manufacturing process of particle board.
• FIG. 6 is a partially enlarged cross-sectional view showing in comparison the mat before the hot pressing step and the particle board formed after the hot pressing step.
• FIG. 7 shows the results of an experiment to verify the effects of the first embodiment.
• FIG. 8 shows the results of an experiment to verify the effect of the second embodiment.
• the particle board 10 is a board in which a large number of wood pieces 1, ..., 1 are bonded together in a collective state.
• the particle board 10 contains a large number of wood pieces 1, ..., 1 and an adhesive.
• the feature of the present invention is the constituent material (wood pieces 1) of the particle board 10, and the thickness and density are not particularly limited.
• the particle board 10 can be configured, for example, as a particle board specified in JIS A5908, so that the thickness is 5 mm to 40 mm and the density is 400 kg/m 3 to 900 kg/m 3.
• the bending strength is superior to that of a conventional particle board containing only wood crushed pieces 2, ..., 2. Therefore, for example, even if the thickness is 3 mm or more but less than 5 mm, sufficient bending strength can be ensured, and even if the density is less than 400 kg/m 3, sufficient bending strength and peeling strength can be ensured.
• the numerous wood pieces 1, 1 constituting the particle board 10 are a mixture of numerous wood crushed pieces 2, 2 and numerous wood shavings 3, 3.
• the wood crushed pieces 2, 2 are used as wood pieces in conventional particle boards, and the wood shavings 3, 3 are used as a constituent material of another wood board 50, which will be described later.
• a mixture of the wood crushed pieces 2, 2 used in conventional particle boards and the wood shavings 3, 3 used as a constituent material of another wood board 50 is used as the numerous wood pieces 1, 1.
• the wood shavings 3, 3 are mixed in a ratio of 10% by weight to 90% by weight with respect to the total weight of the wood pieces 1, 1.
• the wood pulverized pieces 2, ..., 2 are obtained by finely crushing the wood material A with a known crushing device such as a crusher, hammer mill, pin mill, jet mill, ring flaker, cutter mill, etc. until it passes through a sieve with a predetermined opening provided at the outlet of the crushing device.
• a known crushing device such as a crusher, hammer mill, pin mill, jet mill, ring flaker, cutter mill, etc.
• the wood chips 2a, ..., 2a obtained by crushing the wood material A are classified using two types of sieves, one large and one small. For classification, a first sieve with an opening of 16 mm or less and a second sieve with an opening of 0.5 mm or more and smaller than the first sieve are used.
• the first wood chips 2b, ..., 2b selected by classification i.e., passing through the first sieve and not passing through the second sieve
• a sieve having a mesh size of 16 mm or less for example, a sieve having a nominal mesh size of 2 mm or more and 16 mm or less as specified in JIS Z8801-1:2019 can be used, preferably a sieve having a nominal mesh size of 2.8 mm or more and 8 mm or less, and particularly preferably a sieve having a nominal mesh size of 4 mm or more and 5.6 mm or less.
• a sieve having a mesh size of 0.5 mm or more and smaller than the first sieve for example, a sieve having a nominal mesh size of 0.5 mm or more and 2 mm or less as specified in JIS Z8801-1:2019 can be used, preferably a sieve having a nominal mesh size of 0.5 mm or more and 1.4 mm or less, and particularly preferably a sieve having a nominal mesh size of 0.5 mm or more and 1 mm or less.
• the wood chips 2a, ..., 2a are classified using a sieve (first sieve) with a nominal mesh size of 4 mm and a sieve (second sieve) with a nominal mesh size of 1 mm, and the selected wood chips (i.e., the chips pass through the first sieve but do not pass through the second sieve) are used as the first wood chips 2b, ..., 2b.
• first sieve first sieve
• second sieve a sieve with a nominal mesh size of 1 mm
• the third wood chips 2d, ..., 2d which are coarser than the first wood chips 2b, ..., 2b, may not be used as wood crushed pieces 2, ..., 2, but may be returned to the crushing device and crushed again.
• the species of wood material A is not particularly limited, and any species of wood can be used as wood material A.
• fir wood such as cedar, cypress, and Douglas fir, acacia, aspen, poplar, pine (hard pine, soft pine, radiata pine, etc.), birch, rubber (rubber tree), etc. can be used as wood material A.
• domestic materials such as Abies sachalinensis, larch, Yezo spruce, sawara, hiba, kaya, tsuga, cypress, various pines, paulownia, maple, birch (white birch), shiitake, beech, oak, fir, Japanese oak, camphor, and zelkova; North American materials such as American cypress, American hiba, American cedar, American fir, spruce, American tsuga, and redwood; South Sea materials such as agathis, terminalia, lauan, meranti, junkon, chamerele, carampayan, amberoi, melina, teak, apitong, and sengon laut; and other imported materials such as balsa, cedar, mahogany, lignum vitae, acacia mangium, Mediterranean pine, sorghum, and chamerele.
• other imported materials such as balsa, cedar, mahogany,
• the wood cutting pieces 3, 3 are produced from the wood material B when a wood board 50 different from the particle board 10 according to the present invention is formed.
• the wood board 50 is formed by cutting the wood material B into a thin and uniform thickness using a known cutting device having a blade for cutting the material into a thin and uniform thickness, and then crushing the resulting wood flakes 3a, 3a with a uniform thickness t (0.05 mm to 0.35 mm) into a thin and uniform thickness using a known crushing device to form a thin and uniform thickness of many wood flakes 3b, 3b, which are then classified using two types of sieves, large and small, and the first wood flakes 3c, 3c selected by the classification are bonded together in a collective state.
• a number of small wood flakes 3b, ..., 3b are formed by further crushing a number of thin wood flakes 3a, ..., 3a having a uniform thickness t (thickness of 0.05 mm or more and 0.35 mm or less) formed by cutting the wood material B, and among these, a number of first small wood flakes 3c, ..., 3c selected by classification are used in appropriate amounts as wood cutting pieces 3, ..., 3 for the particle board 10.
• a third sieve with a mesh size of 35 mm or less and a fourth sieve with a mesh size of 0.5 mm or more and smaller than the third sieve are used.
• a large number of first small wood flakes 3c, ..., 3c are selected, and second small wood flakes 3d, ..., 3d that pass through both the third and fourth sieves (i.e., finer than the first small wood flakes 3c, ..., 3c) and third small wood flakes 3e, ..., 3e that do not pass through both the third and fourth sieves (i.e., coarser than the first small wood flakes 3c, ..., 3c) are also obtained.
• the first small wood flakes 3c, ..., 3c selected by this classification are used as the wood cutting pieces 3, ..., 3.
• those used for the wood board 50 are used as the wood cutting pieces 3, ..., 3 for the particle board 10.
• a sieve with a mesh size of 35 mm or less for example, a sieve with a nominal mesh size of 5.6 mm to 31.5 mm as specified in JIS Z8801-1:2019 can be used, preferably a sieve with a nominal mesh size of 5.6 mm to 16 mm, and particularly preferably a sieve with a nominal mesh size of 5.6 mm to 8 mm.
• a sieve with a nominal mesh size of 0.5 mm to 2 mm as specified in JIS Z8801-1:2019 can be used, preferably a sieve with a nominal mesh size of 0.5 mm to 1.4 mm, and particularly preferably a sieve with a nominal mesh size of 0.5 mm to 1 mm.
• the first small wood flakes 3c, ..., 3c selected by classification using a sieve with a nominal mesh size of 5.6 mm (third sieve) and a sieve with a nominal mesh size of 0.5 mm (fourth sieve) are used as wood cutting pieces 3, ..., 3 in the particle board 10.
• the thickness t of the wood flakes 3a is 0.05 mm or more and 0.35 mm or less, preferably 0.10 mm or more and 0.30 mm or less, more preferably 0.15 mm or more and 0.25 mm or less, and even more preferably 0.15 mm or more and 0.20 mm or less.
• the thickness t of the wood flakes 3a can be changed by changing the thickness setting (e.g., the speed at which the material is fed) of a known cutting device.
• the wood flakes 3a cut by the cutting device will have a uniform thickness t.
• multiple wood flakes 3a, ..., 3a cut by a cutting device whose thickness setting e.g., the speed at which the material is fed
• a cutting device whose thickness setting (e.g., the speed at which the material is fed) is set so that the thickness of the wood flakes 3a is t will have the same thickness t.
• the small wood flakes 3b and the first to third small wood flakes 3c to 3e that are obtained by classifying the small wood flakes 3b are crushed wood flakes 3a, they have a uniform thickness t, just like the wood flakes 3a.
• the numerous small wood flakes 3b, ..., 3b, the numerous small wood flakes 1 to 3c, ..., 3c, the numerous small second wood flakes 3d, ..., 3d, and the numerous small third wood flakes 3e, ..., 3e each have the same thickness t.
• the wood flakes 3a (as well as the smaller wood flakes 3b, the first smaller wood flakes 3c, the second smaller wood flakes 3b and the third smaller wood flakes 3e) have a uniform thickness t" means that thickness variations due to processing errors of the cutting device are allowed, for example, a thickness variation of about ⁇ 20% is allowed.
• the first small wood flakes 3c, ..., 3c selected by classification can be used as the wood cutting pieces 3, ..., 3 in the particle board 10.
• the wood cutting pieces 3, ..., 3 that constitute the particle board 10 are not limited to the first small wood flakes 3c, ..., 3c.
• the small wood flakes 3b, ..., 3b before classification after crushing, and the second small wood flakes 3d, ..., 3d and the third small wood flakes 3e, ..., 3e that are not used in the wood board 50 may also be used as the wood cutting pieces 3, ..., 3 that constitute the particle board 10.
• the species of wood material B is not particularly limited, and any species of wood can be used as wood material B.
• fir materials such as cedar, cypress, and Douglas fir, acacia, aspen, poplar, pine (hard pine, soft pine, radiata pine, etc.), birch, rubber (rubber tree), etc. can be used as wood material B.
• the moisture content of the wood pieces 1 is preferably 2% or more and 20% or less, and more preferably 2% or more and 8% or less. If the moisture content is less than 2%, it may take a long time to soften the wood during the hot press process in the press molding process, which may lengthen the pressing time and reduce the bending strength. On the other hand, if the moisture content of the wood pieces 1 exceeds 20%, it may take a long time to heat and compress the wood during the hot press process, and the hardening of the adhesive may be inhibited, which may reduce the bending strength.
• the adhesive used for the particle board 10 is not particularly limited as long as it is a thermosetting adhesive.
• an isocyanate-based adhesive can be used.
• amine-based adhesives such as phenolic resin, urea resin, and melamine resin, and natural adhesives can also be used.
• the adhesive is applied to the wood pieces 1, ..., 1 before they are piled up, and hardens when the mat on which the wood pieces 1, ..., 1 are piled up is hot-pressed. This causes the numerous wood pieces 1, ..., 1 to be bonded together in a collective state.
• (Material preparation step S111) First, prepare a wooden material A. When using raw wood such as logs or thinned wood, the logs are cut into short pieces and the bark is removed to prepare the wooden material A. When using scraps or waste materials generated at construction sites, waste pallet materials, recycled materials, etc., the logs are cut into short pieces to prepare the wooden material A.
• the wood chips 2a, ..., 2a obtained by crushing are classified into three sizes using two types of sieves (first and second sieves), large and small. Specifically, the wood chips 2a, ..., 2a are divided into first wood chips 2b, ..., 2b of the desired size that pass through the first sieve with a coarse mesh and do not pass through the second sieve with a fine mesh, second wood chips 2c, ..., 2c that are finer than the first wood chips 2b, ..., 2b that pass through both the first and second sieves, and third wood chips 2d, ..., 2d that are coarser than the first wood chips 2b, ..., 2b that do not pass through both the first and second sieves.
• first and second sieves two types of sieves
• the first wood chips 2b, ..., 2b classified and selected in this way are called wood crushed pieces 2, ..., 2.
• the third wood chips 2d, ..., 2d are not used as the wood pulverized pieces 2, ..., 2 but are returned to the pulverizing device and pulverized again.
• the wood cutting piece production process S12 includes a material preparation process S121, a cutting process S122, a crushing process S123, and a classification process S124. As described above, in the present embodiment 1, the first wood thin pieces 3c, ..., 3c generated during the formation of the wood board 50 are used as the wood cutting pieces 3, ..., 3. Therefore, the wood cutting piece production process S12 is a part of the process of the manufacturing method of the wood board 50.
• (Material preparation step S121) First, prepare a wood material B. When logs, thinned wood, or other raw wood are used, they are cut into short pieces and the bark is removed to prepare the wood material B. When scraps or waste materials generated at construction sites, waste pallet materials, recycled materials, or the like are used, they are cut into short pieces to prepare the wood material B.
• the prepared wood material B is cut into a thin and uniform thickness by a known cutting device having a blade for cutting the material into a thin and uniform thickness to form a large number of wood flakes 3a, ..., 3a with a uniform thickness t.
• the thickness setting of the cutting device e.g., the speed at which the wood material B is fed
• the thickness setting of the cutting device is adjusted to form a large number of wood flakes 3a, ..., 3a with a uniform thickness t and with fibers a appearing linearly on the surface.
• the thickness of the small wood pieces 3b, ..., 3b obtained in the next crushing process will also be thickness t.
• the wood flakes 3a, ..., 3a When force is applied to the wood flakes 3a, ..., 3a in a random direction, the wood flakes 3a, ..., 3a usually break from the parts where the force is weak (they tend to break in the direction of the weak force). Since the force connecting each fiber of the wood flakes 3a, ..., 3a (force perpendicular to the fiber direction) is overwhelmingly weaker than the force in the fiber direction, if the wood flakes 3a, ..., 3a are broken in the fiber direction by the above-mentioned crushing device (when force is applied), the wood flakes 3a, ..., 3a break along the fiber direction and shorten in the fiber direction, and small, slender wood flakes 3b, ..., 3b are obtained.
• the woody small flakes 3b, ..., 3b obtained by pulverization are classified into three sizes using two types of sieves (third and fourth sieves), large and small. Specifically, the woody small flakes 3b, ..., 3b are divided into the first woody small flakes 3c, ..., 3c of the desired size that pass through the coarse third sieve and do not pass through the fine fourth sieve, the second woody small flakes 3d, ..., 3d that pass through both the third and fourth sieves (i.e., finer than the first woody small flakes 3c, ..., 3c), and the third woody small flakes 3e, ..., 3e that do not pass through both the third and fourth sieves (i.e., coarser than the first woody small flakes 3c, ..., 3c).
• the first woody small flakes 3c, ..., 3c classified and selected in this way are called woody cutting pieces 3, ..., 3.
• wood pieces 1, ..., 1 (a mixture of first wood chips 2b, ..., 2b and first small wood pieces 3c, ..., 3c) are produced by the above-mentioned wood crushed piece production process S11, wood cutting piece production process S12, and wood piece mixing process S13.
• ⁇ Adhesive application step S2> The numerous wood pieces 1, ..., 1 produced in the wood piece production step S1 are carried into an adhesive applicator, where adhesive is applied.
• an isocyanate-based adhesive can be used, and other adhesives such as phenolic resin, amine-based adhesives such as urea resin and melamine resin, and natural wood (tannin)-based adhesives may also be used.
• a commonly used water repellent may also be used together with the adhesive.
• ⁇ Heat pressing step S4> The mat 9 formed in the mat forming process S3 is carried into a hot press device and set between hot plates, where the mat 9 is compressed by hot pressing at a predetermined pressure and temperature. At this time, the adhesive hardens, bonding the numerous wood pieces 1, 1 together. As a result, the particle board 10 shown on the right side of Fig. 6 is formed.
• the crushed wood chips which are not cut to a thin thickness, are crushed during press molding, and when moisture penetrates the interior, the crushed wood chips absorb the moisture and tend to swell, resulting in large changes in dimensions (changes in length and thickness).
• the particle board 10 of this embodiment 1 has a structure that makes it more difficult for moisture to penetrate into the interior than conventional particle boards, as described above, and the numerous replaced wood cutting pieces 3, ..., 3 are cut to a thin thickness, so there is no large change in dimensions (length and thickness) due to absorption of moisture.
• Test specimen X0 was constructed in the same manner as a conventional particle board that does not include wood cuttings 3, ..., 3, and test specimens X1 to X4 have different mixing ratios of wood cuttings 3, ..., 3, and the other configurations are constructed in the same manner as the particle board 10 of embodiment 1 (the first wood chip 2b was selected as the wood crushed piece 2, and the first wood thin piece 3c was selected as the wood cutting piece 3).
• FIG. 7 shows the results of each test of test specimens X1 to X4 in a relative ratio when the result of each test of test specimen X0 is set to 100.
• the particleboard 10 (specimens X1 to X4) containing the wood shavings 3, ..., 3 showed improved water absorption thickness expansion rate (TS) and water absorption length change rate (LE) compared to the conventional particleboard (specimen X0) that did not contain the wood shavings 3, ..., 3.
• TS water absorption thickness expansion rate
• LE water absorption length change rate
• the improvement rate of water absorption thickness expansion rate (TS) was slightly lower than that of water absorption length change rate (LE)
• the absolute value of water absorption thickness expansion rate (TS) fully met the standard (12% or less) required for structural particleboard.
• the improvement rate of water absorption length change rate (LE) increased as the mixing ratio of the wood shavings 3, ..., 3 increased.
• the particle boards 10 containing wood shavings 3, ..., 3 showed improved strength compared to the conventional particle board (test specimen X0) that did not contain wood shavings 3, ..., 3.
• the particle board 10 of the second embodiment contains not only the normally contained pulverized wood chips 2, ..., 2, but also extremely thin shaved wood chips 3, ..., 3 with a thickness of 0.05 mm to 0.35 mm, so that it can achieve the same effects as the particle board 10 of the first embodiment.
• the inventors of the present application also prepared the following five types of particle boards 10 (specimens X10 to X14) in the second embodiment, and conducted bending strength tests, water absorption thickness swelling tests, water absorption length change tests, and wood screw holding strength tests in accordance with JIS A5908 and JIS A5905 to determine the normal bending strength (MOR), water absorption thickness swelling test (TS), water absorption length change test (LE), and wood screw holding strength (WS). They also conducted a moisture absorption and release test to determine the moisture absorption and release length change test (HLE), with the results shown in Figure 8.
• Specimen X10 Wood cuttings 3, ..., 3 mixed at 0% by weight
• Specimen X11 Wood cuttings 3, ..., 3 mixed at 20% by weight
• Specimen X12 Wood cuttings 3, ..., 3 mixed at 40% by weight
• Specimen X13 Wood cuttings 3, ..., 3 mixed at 60% by weight
• Specimen X14 Wood cuttings 3, ..., 3 mixed at 80% by weight
• particle boards 10 (specimens X11-X14) containing 20% or more by weight of wood cuttings 3, ..., 3 had improved MOR (materials of normal operation) compared to conventional particle board (specimen X10) that did not contain wood cuttings 3, ..., 3, and when the mixing ratio of wood cuttings 3, ..., 3 was 40% or more by weight, the improvement rate was extremely high at 50% or more. The higher the mixing ratio of wood cuttings 3, ..., 3, the higher the improvement rate of MOR, resulting in improved bending strength.
• the particleboard 10 containing the wood shavings 3, ..., 3 showed no improvement in water absorption thickness expansion rate (TS) compared to the conventional particleboard (specimen X10) that did not contain the wood shavings 3, ..., 3, but the absolute value of the water absorption thickness expansion rate (TS) fully met the standard (12% or less) required for structural particleboards.
• the particleboard 10 containing the wood shavings 3, ..., 3 showed an improvement in water absorption length change rate (LE) compared to the conventional particleboard (specimen X10) that did not contain the wood shavings 3, ..., 3, and the higher the mixing ratio of the wood shavings 3, ..., 3, the higher the improvement rate, resulting in less dimensional change due to water absorption.
• the particle board 10 (specimens X11-X14) containing the wood shavings 3, ..., 3 showed an improved moisture absorption and release length change rate (HLE) compared to the conventional particle board (specimen X10) that did not contain the wood shavings 3, ..., 3.
• the moisture absorption and release length change rate (HLE) improved more as the mixing ratio of the wood shavings 3, ..., 3 increased, and dimensional change due to moisture absorption and release became less likely to occur.
• the mixing ratio of the wood shavings 3, ..., 3 was 40% by weight or more, the improvement rate exceeded 40%, resulting in an extremely high rate.
• the particle board 10 containing the wood shavings 3, ..., 3 showed improved results compared to the conventional particle board (test specimen X10) that did not contain the wood shavings 3, ..., 3.
• the root mean square height Sq and arithmetic mean height Sa (indicators of surface quality) of the surfaces of test specimen X10 and test specimens X11 to X14 were measured and compared, and all were found to be roughly the same, with only differences of about 1 to 4 ⁇ m.
• the particleboard 10 (specimens X11-X14) containing the wood shavings 3, ..., 3 had higher bending strength (MOR) and wood screw holding power (WS) (bending strength and screw pull-out strength were improved) and lower water absorption length change (LE) and moisture absorption/desorption length change (HLE) (dimensional changes due to water absorption and moisture absorption/desorption were less likely to occur) compared to the conventional particleboard (specimen X10) that did not contain the wood shavings 3, ..., 3.
• MOR bending strength
• WS wood screw holding power
• HLE moisture absorption/desorption length change
• the particleboard 10 (specimens X11-X14) containing the wood shavings 3, ..., 3 had similar root mean square height Sq and arithmetic mean height Sa (indicators of surface properties) on the surface to the conventional particleboard (specimen X10) that did not contain the wood shavings 3, ..., 3.
• Sq root mean square height
• Sa arithmetic mean height
• the wood cutting pieces 3, ..., 3 used in the particle board 10 are not limited to the first small wood flakes 3c, ..., 3c, and at least one type of wood flakes 3a, ..., 3a, small wood flakes 3b, ..., 3b, first small wood flakes 3c, ..., 3c, second small wood flakes 3d, ..., 3d, and third small wood flakes 3e, ..., 3e can be used.
• the particle board 10 can be formed more inexpensively, and the wood material B of the other wood boards 50 is used without waste, which leads to effective use of wood resources.
• the first wood chips 2b, ..., 2b are used as the wood crushed chips 2, ..., 2
• the second wood chips 2c, ..., 2c are used as the wood crushed chips 2, ..., 2
• the wood crushed chips 2, ..., 2 used in the particle board 10 are not limited to the above examples.
• the wood crushed chips 2, ..., 2 used in the particle board 10 may be third wood chips 2d, ..., 2d that do not pass through both the first and second sieves during classification (i.e., coarser than the first wood chips 2b, ..., 2b) or wood chips 2a, ..., 2a before classification.
• any two, or any three of the wood chips 2a, ..., 2a, the first wood chips 2b, ..., 2b, the second wood chips 2c, ..., 2c, and the third wood chips 2d, ..., 2d may be combined and used as the wood pulverized pieces 2, ..., 2.
• at least one of the wood chips 2a, ..., 2a, the first wood chips 2b, ..., 2b, the second wood chips 2c, ..., 2c, and the third wood chips 2d, ..., 2d may be used as the wood pulverized pieces 2, ..., 2.
• the present invention is useful for particle boards and methods for manufacturing particle boards.

Landscapes

• Life Sciences & Earth Sciences (AREA)
• Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Wood Science & Technology (AREA)
• Forests & Forestry (AREA)
• Dry Formation Of Fiberboard And The Like (AREA)
• Debarking, Splitting, And Disintegration Of Timber (AREA)

Priority Applications (1)

Applications Claiming Priority (2)

Publications (1)

Family

ID=92419371

Family Applications (1)

Country Status (2)

Citations (9)

Family Cites Families (2)

• 2023
  • 2023-09-12 JP JP2023147940A patent/JP7536157B1/ja active Active
• 2024
  • 2024-08-05 WO PCT/JP2024/027978 patent/WO2025057615A1/ja active Pending
  • 2024-08-05 JP JP2024565028A patent/JP7802207B2/ja active Active

Patent Citations (9)

Also Published As

Similar Documents

Legal Events