Method of manufacturing a fiberboard and compression material for manufacturing a fiberboard

Abstract

A method of producing a fiberboard, which includes a compression step, a steaming and fiber separation step, a molding step, and a hot-pressing step. The compression step includes compressing a mixture containing a ground product of a plant and a water-soluble boron compound to obtain a compressed material. The steaming and fiber separation step includes steaming and fiber separation of the compressed material to obtain a wood fiber. The molding step includes adding a binder to the wood fiber, and then molding the wood fiber to obtain a mat-like molded product. The hot-pressing step includes pressing the mat-like molded product while heating the mat-like molded product.

Description

Technical Field

[0001] The present invention generally relates to methods for preparing fiberboard and compression materials for preparing fiberboard, and more specifically, to a method for preparing fiberboard from a milled product of plants and compression materials for preparing fiberboard. Background Technology

[0002] Patent document 1 discloses a building material. The building material includes a base material, a surface material bonded to the base material with an adhesive, and pigments and coating materials applied to the surface material.

[0003] Here, wood with mite-repellent properties is used as both the base and surface materials. Specifically, examples of mite-repellent wood include Japanese cypress, northern white cedar, Japanese cypress, Lawson cypress, and Japanese cedar.

[0004] In addition, adhesives, pigments, and coating materials include acaricides incorporated therein. Specifically, examples of acaricides include ethfenprox, wasaouro, hinokitiol, IBTA, and natural pyrethroids.

[0005] However, Patent Document 1 does not discuss the case where wood without anti-mite properties is used. When wood without anti-mite properties is used as the base material and surface material, anti-mite substances added alone to adhesives, pigments, and coating materials are difficult to maintain their anti-mite effect for a long time.

[0006] Reference List

[0007] Patent documents

[0008] Patent Document 1: JP 2000-160716 A Summary of the Invention

[0009] The purpose of this invention is to provide a method for preparing fiberboard with long-term mite-proof properties and a compression material for preparing fiberboard.

[0010] According to one aspect of the present invention, a method for preparing a fiberboard includes: a compression step of compressing a mixture comprising a ground product of a plant and a water-soluble boron compound to obtain a compressed material; a steaming and fiber separation step of steaming and separating the compressed material to obtain wood fibers; a forming step of adding an adhesive to the wood fibers and then molding the wood fibers to obtain a cushion-shaped molded product; and a hot pressing step of pressing the cushion-shaped molded product while heating it.

[0011] According to one aspect of the invention, a compressed material for preparing fiberboard is a compressed material obtained by compressing a mixture comprising a milled product of a plant and a water-soluble boron compound. Detailed Implementation

[0012] 1. Overview

[0013] The method for preparing fiberboard according to this embodiment includes a compression step, a steaming and fiber separation step, a forming step, and a hot pressing step.

[0014] The compression step involves compressing a mixture containing a plant-based grinding product and a water-soluble boron compound to obtain a compressed material. The water-soluble boron compound is the component that imparts mite-repellent properties to the fiberboard. The water-soluble boron compound is readily soluble in water; therefore, when added to the plant-based grinding product, the water-soluble boron compound dissolves in the moisture within the grinding product and can penetrate into it.

[0015] The steaming and fiber separation steps involve steaming and separating the compressed material to obtain wood fibers. Since water-soluble boron compounds are inorganic compounds, they are not easily decomposed even in high-temperature and high-humidity environments. Therefore, water-soluble boron compounds retain their ability to impart anti-mite properties. Furthermore, water-soluble boron compounds are easily attached to wood fibers.

[0016] The molding step includes adding an adhesive to the wood fibers and then molding the wood fibers to obtain a mat-shaped molded product. Because water-soluble boron compounds readily adhere to the wood fibers, they can be uniformly dispersed in the mat-shaped molded product.

[0017] The hot-pressing step involves pressing the pad-shaped molded product while heating it. This yields a fiberboard. An adhesive fixes a water-soluble boron compound. Specifically, the water-soluble boron compound is fixed in a uniformly dispersed state within the fiberboard. More specifically, the water-soluble boron compound may be present not only on the surface of the fiberboard but also throughout the fiberboard.

[0018] Therefore, this implementation scheme enables the preparation of fiberboard with long-term mite-proof properties.

[0019] 2. Detailed Explanation

[0020] (1) First Implementation Plan

[0021] The method for preparing a fiberboard according to a first embodiment will now be described. Examples of fiberboard include insulation boards, medium-density fiberboard (MDF), and hardboard. Medium-density fiberboard is preferred.

[0022] The method for preparing fiberboard includes a compression step, a steaming and fiber separation step, a forming step, and a hot pressing step. These steps will be described in turn below.

[0023] <Compression Steps>

[0024] The compression step involves compressing a mixture comprising a ground plant product and a water-soluble boron compound to obtain a compressed material (hereinafter also referred to as "compressed material") for the preparation of fiberboard. The compressed material has, for example, a pellet shape. To obtain the compressed material, a pelletizing machine (pelletizer) can be used, for example. There are no particular limitations on pelletizing machines, examples of which include ring die forming machines and flat die forming machines. There are no particular limitations on the pressure during compression, for example, greater than or equal to 0.5 MPa and less than or equal to 1.0 MPa.

[0025] The plant is ground into chips by grinding the plant using a shredder. There are no particular restrictions on the shape of each chip; for example, it can be cylindrical. The size of each chip is, for example, a length greater than or equal to 0.8 mm and less than or equal to 50 mm, and an outer diameter greater than or equal to 0.1 mm and less than or equal to 2 mm. There are no particular restrictions on the type of plant; examples include coniferous and broadleaf tree materials.

[0026] There are no particular restrictions on the species of coniferous material, and examples include Japanese yew, Japanese fir, Pihuta, Japanese larch, Yezomatsu, Japanese red pine, Japanese black pine, Japanese white pine, Tsuga, Japanese cedar, Japanese umbrella pine, Japanese cypress, Japanese cypress, Japanese thuja, and Hiba.

[0027] There are no particular restrictions on the species of broad-leaved trees used for this purpose. Examples include palm, monarchbirch, sweet chestnut, Japanese beech, Mizunara, Japanese elm, Japanese zelkova, Katsura, camphor tree, painted maple, Chinese red ash, apitong, redlauan, and teak.

[0028] Plants may or may not have anti-mite properties.

[0029] The preferred plant is a palm family (Arecaceae). There are no particular limitations on palm family plants; examples include oil palm. Oil palm is a palm tree grown in countries such as Malaysia, Indonesia, Thailand, and Colombia. Oil palm trunks (OPT) are insufficiently strong for building materials and are therefore disposed of as unused resources. Furthermore, oil palm trunks contain sugar and are easily decomposed, so currently they are left to rot. However, the decomposition of oil palm trunks produces greenhouse gases, thus raising environmental concerns. In the first embodiment, palm family plants can be used as plants for fiberboard manufacturing, thus making efficient use of resources. Note that the fruit of the oil palm is used to extract edible oil, etc.

[0030] When using palm plants, it is preferable to wash the milled product with water before supplying the water-soluble boron compound to reduce the ash and / or sugar content, then dry it to adjust the moisture content, and finally supply the water-soluble boron compound to the milled product. This reduces process failures caused by ash and / or sugar content in steps such as steaming, which will be described later.

[0031] Water-soluble boron compounds are the components that impart mite-resistant properties to fiberboard. Here, "mite-resistant properties" means the ability to inhibit mite proliferation for a prolonged period (at least 6 weeks).

[0032] Water-soluble boron compounds are readily soluble in water. Therefore, when a water-soluble boron compound is added to a plant grinding product, it dissolves in the moisture of the grinding product and can penetrate into it. Note that a water-soluble boron compound pre-dissolved in water can be supplied to the plant grinding product. In this case, the water-soluble boron compound, along with the moisture in the grinding product, can also penetrate into it.

[0033] Furthermore, since water-soluble boron compounds are inorganic compounds, they are less prone to decomposition even in high-temperature and high-humidity environments compared to the insecticidal components of organic compounds represented by pyrethroids. Here, "high temperature" means a temperature higher than or equal to 100°C, and additionally, "high temperature" includes, for example, the temperature conditions in the steaming and fiber separation steps described later. Furthermore, "high humidity" means a relative humidity higher than or equal to 90% RH, and additionally, "high humidity" includes, for example, the humidity conditions in the steaming and fiber separation steps described later.

[0034] Preferably, the water-soluble boron compound comprises at least one type of compound selected from the following: boric acid (B(OH)3), borax (Na2B4O5(OH)4·8H2O), disodium octaborate tetrahydrate (DOT, Na2B8O) 13 (·4H2O) and sodium polyborate. This further improves the mite-proof properties of the fiberboard. Among the above water-soluble boron compounds, sodium polyborate is preferred. This is because sodium polyborate is very soluble in water and also has the ability to impart flame retardancy.

[0035] The amount (content) of water-soluble boron compounds in the compression material is preferably managed based on the amount (content) of boron added to the compression material.

[0036] The amount (content) of boron in the water-soluble boron compound in the compressed material is preferably greater than or equal to 0.05% by mass and less than or equal to 0.5% by mass. An addition of greater than or equal to 0.05% by mass can further improve the mite-proof properties of the fiberboard. An addition of less than or equal to 0.5% by mass suppresses the reduction in the peel strength of the fiberboard. Note that the amount of boron added to the water-soluble boron compound in the compressed material refers to the amount of boron added to obtain the compressed material. Conversely, the boron content of the water-soluble boron compound in the compressed material refers to the amount of boron contained in the compressed material. The water-soluble boron compound does not decompose or react due to compression; therefore, in the first embodiment, the amount of boron added to the water-soluble boron compound in the compressed material and the boron content of the water-soluble boron compound in the compressed material are substantially equal to each other.

[0037] The specific gravity of the compressed material is preferably greater than or equal to 0.35 and less than or equal to 1.50, more preferably greater than or equal to 0.40 and less than or equal to 1.50. Therefore, the mechanical durability of the compressed material is improved, and it is less likely to break or fracture during transportation. Furthermore, the fibrous structure contained in the compressed material is less likely to be damaged by compression, which readily improves the strength properties of the resulting fiberboard.

[0038] The water content of the compressed material is preferably less than or equal to 25% by mass, more preferably less than or equal to 20% by mass. A water content of less than or equal to 25% by mass improves the shape retention of the compressed material. Furthermore, when the plant is a palm, a water content of less than or equal to 25% by mass can prevent the decay of the fibers contained in the compressed material, and thus improve the storage characteristics of the compressed material. Note that the water content of the compressed material can be determined by drying. The water content of the compressed material can be adjusted by drying the mixture after compression, but is preferably based on the water content of the plant's milled product during compression. Specifically, the water content of the compressed material can be adjusted based on the drying conditions after supplying the water-soluble boron compound to the plant's milled product. Note that the plant's milled product is dried and its water content is adjusted before supplying the water-soluble boron compound.

[0039] <Steaming and Fiber Separation Steps>

[0040] The steaming and fiber separation step is a step of fiberizing the compressed material. Specifically, the steaming and fiber separation step involves steaming and separating the compressed material to obtain lignocellulose. Specifically, saturated steam is introduced into the compressed material to soften the lignin and decompose the compressed material to obtain fibers or fiber bundles, thereby obtaining lignocellulose. In the steaming and fiber separation step, a known steaming and fiber separation apparatus can be used.

[0041] Here, there are no particular restrictions on the temperature during steaming, for example, above or equal to 150°C and below or equal to 200°C. There are no particular restrictions on the relative humidity during steaming, for example, above or equal to 90% RH. There are no particular restrictions on the time period of the steaming and fiber separation steps, for example, longer than or equal to 1 minute and shorter than or equal to 15 minutes.

[0042] During the steaming and fiber separation steps, the compressed material is subjected to high temperature and high humidity. However, as mentioned above, even when water-soluble boron compounds are exposed to high temperature and high humidity, they are not easily decomposed. Therefore, water-soluble boron compounds retain their ability to impart anti-mite properties. Furthermore, water-soluble boron compounds readily attach to wood fibers, thus suppressing the loss of water-soluble boron compounds in subsequent steps after steaming and fiber separation. Conversely, the insecticidal components of organic compounds, such as pyrethroids, are easily decomposed under high temperature and high humidity. Therefore, their ability to impart anti-mite properties is more likely to decrease.

[0043] Here, in the steaming and fiber separation steps, only the aforementioned compressed material (i.e., the compressed material for fiberboard according to the first embodiment) is used; however, in addition to the aforementioned compressed material, materials free of water-soluble boron compounds may also be used. Examples of materials free of water-soluble boron compounds include the following first and second materials.

[0044] The first material is a milled product used to prepare conventional medium-density fiberboard. Specifically, the first material is not particularly limited, and examples include milled products of South-sea wood and milled products of coniferous trees.

[0045] The second material is a compressed material obtained by simply compressing the ground product of the aforementioned plants (i.e., without adding water-soluble boron compounds).

[0046] In the steaming and fiber separation steps, when a material free of water-soluble boron compounds is used in addition to the aforementioned compressed material (i.e., the compressed material for fiberboard according to the first embodiment), it is preferable to increase the amount of water-soluble boron compounds added to the compressed material according to the mass ratio of the water-soluble boron compounds to the material free of water-soluble boron compounds. For example, the same amount of water-soluble boron compounds as the compressed material can also be used, and in this case, in order to ensure that the content of water-soluble boron compounds in the material as a whole is within the aforementioned preferred range (greater than or equal to 0.05% by mass and less than or equal to 0.5% by mass of boron), the amount of boron added to the water-soluble boron compounds in the compressed material falls within double the range (greater than or equal to 0.1% by mass and less than or equal to 1.0% by mass).

[0047] <Forming Steps>

[0048] The molding step involves adding an adhesive to the wood fibers and then molding the wood fibers to obtain a mat-shaped molded product. Molding is preferably performed by a drying method. In dry molding, a known gravity molding machine or a vacuum molding machine can be used. Note that, in addition to the adhesive, a water-repellent agent may also be added.

[0049] There are no particular limitations on the adhesives used here, and examples include diphenylmethane diisocyanate (MDI), urea-formaldehyde resin, urea-melamine cocondensate resin, and phenolic resin.

[0050] There are no particular restrictions on the amount of adhesive added relative to the total mass of wood fibers and adhesive, for example, greater than or equal to 1% by mass and less than or equal to 10% by mass.

[0051] <Hot pressing steps>

[0052] The hot pressing step involves pressing the pad-shaped molded product while heating it. A known hot press can be used in the hot pressing step. A spacer (thickness gauge) can be connected between the heating plates of the hot press. This spacer helps to ensure uniform thickness of the fiberboard.

[0053] There are no particular restrictions on the heating temperature, for example, above or equal to 140°C and below or equal to 230°C. There are no particular restrictions on the compression pressure, for example, above or equal to 0.5 MPa and below or equal to 10 MPa. There are no particular restrictions on the hot-pressing time period, for example, longer than or equal to 10 seconds and shorter than or equal to 3 minutes.

[0054] As described above, a fiberboard according to the first embodiment was obtained. The thickness of the fiberboard is not particularly limited, for example, greater than or equal to 1 mm and less than or equal to 20 mm.

[0055] <Other>

[0056] The method for preparing fiberboard may further include a humidity conditioning step. This humidity conditioning step includes leaving the fiberboard in the atmosphere for a period of time after the hot-pressing step, or treating the fiberboard in a humidity controller after the hot-pressing step. Since the moisture content of the fiberboard is very low after the hot-pressing step, it is preferable to increase the humidity to a level close to the moisture content of the equilibrium operating conditions.

[0057] <Operation and Advantages>

[0058] As described above, the method for preparing fiberboard according to the first embodiment includes a compression step, a steaming and fiber separation step, a forming step, and a hot pressing step.

[0059] The compression step involves compressing a mixture containing a plant-derived mill product and a water-soluble boron compound to obtain a compressed material. The water-soluble boron compound is readily soluble in water; therefore, when added to the plant-derived mill product, the compound dissolves in the moisture content of the mill product and can permeate into it. Thus, adding the water-soluble boron compound to the compressed material in the initial stage of fiberboard preparation ultimately promotes the presence of the water-soluble boron compound in the fiberboard.

[0060] The steaming and fiber separation steps involve steaming and separating the compressed material to obtain wood fibers. Since water-soluble boron compounds are inorganic compounds, they are not easily decomposed even in high-temperature and high-humidity environments. Therefore, water-soluble boron compounds retain their ability to impart anti-mite properties. Furthermore, water-soluble boron compounds readily attach to wood fibers. Thus, the separation of water-soluble boron compounds from wood fibers and their loss during fiberboard preparation are suppressed.

[0061] The molding step includes adding an adhesive to the wood fibers and then molding the wood fibers to obtain a mat-shaped molded product. Because water-soluble boron compounds readily adhere to the wood fibers, they can be uniformly dispersed in the mat-shaped molded product.

[0062] The hot-pressing step involves pressing the pad-shaped molded product while heating it. This yields a fiberboard. An adhesive fixes a water-soluble boron compound. Specifically, the water-soluble boron compound is fixed in a uniformly dispersed state within the fiberboard. More specifically, the water-soluble boron compound may be present not only on the surface of the fiberboard but also throughout the fiberboard.

[0063] Therefore, the first embodiment enables the preparation of fiberboard with long-term mite-proof properties.

[0064] Furthermore, as mentioned above, water-soluble boron compounds can be present in the fiberboard, thus increasing the range of available plants. That is, the plants themselves do not necessarily need to possess mite-resistant properties.

[0065] Therefore, palm trees, which are currently causing environmental problems, can be effectively used as fiberboard.

[0066] Note that after steaming and fiber separation of the plant grinding products to obtain lignocellulose, water-soluble boron compounds can be added to the lignocellulose, followed by forming and hot-pressing steps to prepare fiberboard. However, in this case, the surface area of ​​the lignocellulose is larger than that of the plant grinding products; therefore, the water-soluble boron compounds are unlikely to be uniformly dispersed. As a result, the distribution of water-soluble boron compounds in the obtained fiberboard is more likely to be uneven, and stable anti-mite properties are difficult to obtain.

[0067] Conversely, in the method for preparing fiberboard according to the first embodiment, a water-soluble boron compound is added to the milled product of plants with a relatively small surface area, thus the water-soluble boron compound is easily and uniformly dispersed. Furthermore, during the steaming and fiber separation steps, the wood fibers are vigorously stirred, therefore the distribution of the water-soluble boron compound fixed to the wood fibers is more likely to be uniform. As a result, the obtained fiberboard tends to have a uniformly distributed water-soluble boron compound and exhibits stable anti-mite properties.

[0068] (2) Second Implementation Plan

[0069] Next, a method for preparing a fiberboard according to a second embodiment will be described. In the second embodiment, detailed descriptions of components similar to those in the first embodiment may be omitted.

[0070] The mixture of the second embodiment differs from the mixture of the first embodiment in that the mixture of the second embodiment also contains a silicate compound. That is, the mixture of the first embodiment contains a ground plant product and a water-soluble boron compound, while the mixture of the second embodiment contains a ground plant product, a water-soluble boron compound, and a silicate compound.

[0071] <Compression Steps>

[0072] The compression step of the second embodiment includes compressing a mixture comprising a ground plant product, a water-soluble boron compound, and a silicate compound to obtain a compressed material. The description of the ground plant product and the water-soluble boron compound is similar to that of the first embodiment.

[0073] When subjected to a water absorption and drying cycle test on fiberboard, the silica compound exhibits the function of inhibiting the reduction of its anti-mite properties. Here, the water absorption and drying cycle test refers to a load test involving repeated cycles of water immersion and drying on the fiberboard (see also [Examples]). When the fiberboard is subjected to this cycle test, the function of the water-soluble boron compound (the function that imparts anti-mite properties to the fiberboard) may decrease. However, since the silica compound and the water-soluble boron compound coexist, the silica compound can inhibit the reduction of the water-soluble boron compound's function. Furthermore, similar to the water-soluble boron compound, the silica compound is an inorganic compound; therefore, it is not easily decomposed even in high-temperature and high-humidity environments.

[0074] Silicates (silicic acid compounds) are salts containing silicon dioxide and metal oxides. There are no particular limitations on silicic acid compounds; examples include sodium silicate (a common name for compounds containing silicon dioxide and sodium oxide), calcium silicate (a common name for compounds containing silicon dioxide and calcium oxide), aluminum silicate (a common name for compounds containing silicon dioxide and aluminum oxide), ferric silicate (a common name for compounds containing silicon dioxide and iron oxide), magnesium silicate (a common name for compounds containing silicon dioxide and magnesium oxide), and potassium silicate (a common name for compounds containing silicon dioxide and potassium oxide).

[0075] The amount (content) of silicate compound added to the compression material is preferably greater than or equal to 40 parts by mass and less than or equal to 60 parts by mass relative to 1 part by mass of boron. In other words, the ratio of silicate compound to boron in the compression material is preferably such that the amount of silicate compound is 40 times or more, and 60 times or less, than the amount of boron. An amount of silicate compound greater than or equal to 40 parts by mass can further suppress the functional degradation of water-soluble boron compounds during cyclic testing of the fiberboard. Even when the amount of silicate compound added is increased to greater than 60 parts by mass, the effect of suppressing the functional degradation of water-soluble boron compounds no longer shows a significant difference; therefore, adding more than 60 parts by mass of silicate compound is uneconomical. Note that the amount of silicate compound added to the compression material refers to the amount of silicate compound added to obtain the compression material. Conversely, the content of silicate compound in the compression material refers to the amount of silicate compound contained in the compression material. Since silicate compounds do not decompose or react due to compression, in the second embodiment, the amount of silicate compound added and the content of silicate compound are substantially equal to each other. Furthermore, 1 part by mass of boron refers to 1 part by mass of boron in a water-soluble boron compound.

[0076] <Steaming and Fiber Separation Steps>

[0077] The steaming and fiber separation steps in the second embodiment are similar to those in the first embodiment. The steaming and fiber separation steps involve subjecting the compressed material to high temperature and high humidity. However, similar to water-soluble boron compounds, as mentioned above, even when exposed to high temperature and high humidity, the silicate compounds are not easily decomposed. Therefore, the silicate compounds retain their ability to inhibit the functional degradation of water-soluble boron compounds.

[0078] <Forming Steps>

[0079] The molding steps of the second embodiment are similar to those of the first embodiment. Similar to water-soluble boron compounds, silica compounds can also be uniformly dispersed in the pad-shaped molded product.

[0080] <Hot pressing steps>

[0081] The hot-pressing step in the second embodiment is similar to that in the first embodiment. Similar to the water-soluble boron compound, the silicate compound is also fixed by an adhesive. That is, similar to the water-soluble boron compound, the silicate compound is fixed in a state where it is uniformly dispersed in the fiberboard. Specifically, similar to the water-soluble boron compound, the silicate compound can exist not only in the surface layer of the fiberboard but also within the fiberboard itself.

[0082] <Other>

[0083] The remainder of the second implementation scheme is similar to the first implementation scheme.

[0084] <Operation and Advantages>

[0085] Similar to the first embodiment, the second embodiment enables the preparation of fiberboard with long-term mite-proof properties.

[0086] Furthermore, in the second embodiment, similar to water-soluble boron compounds, silicate compounds can be present not only on the surface of the fiberboard but also within the fiberboard itself. Therefore, due to the coexistence of silicate compounds and water-soluble boron compounds, the silicate compounds can suppress the functional degradation of the water-soluble boron compounds. That is, when the fiberboard is subjected to cyclic testing (a load test with repeated cycles of water immersion and drying), the silicate compounds suppress the reduction of the fiberboard's anti-mite properties.

[0087] 3. Aspects

[0088] As can be seen from the above implementation scheme, the present invention includes the following aspects.

[0089] The first aspect is a method for preparing fiberboard, comprising a compression step, a steaming and fiber separation step, a forming step, and a hot-pressing step. The compression step comprises compressing a mixture containing a ground plant product and a water-soluble boron compound to obtain a compressed material. The steaming and fiber separation step comprises steaming and separating the fibers from the compressed material to obtain wood fibers. The forming step comprises adding an adhesive to the wood fibers and then molding the wood fibers to obtain a mat-shaped molded product. The hot-pressing step comprises pressing the mat-shaped molded product while heating it.

[0090] This aspect enables the production of fiberboard with long-term mite-proof properties.

[0091] The second aspect is a method for preparing fiberboard based on the first aspect. In the second aspect, the water-soluble boron compound comprises at least one type of compound selected from the group consisting of boric acid, borax, disodium octaborate tetrahydrate, and sodium polyborate.

[0092] This aspect allows for further improvement in the mite-proof properties of fiberboard.

[0093] The third aspect is a method for preparing fiberboard based on the first or second aspect. In the third aspect, the mixture further comprises a silicate compound.

[0094] This aspect inhibits the reduction of anti-mite properties, even when the fiberboard is repeatedly cyclically loaded with water for soaking and drying.

[0095] The fourth aspect is a method for preparing fiberboard based on the third aspect. In the fourth aspect, the amount of silicate compound added to the compressed material is greater than or equal to 40 parts by mass and less than or equal to 60 parts by mass relative to 1 part by mass of boron in the water-soluble boron compound.

[0096] This further inhibits the reduction of anti-mite properties, even when the fiberboard is repeatedly cyclically loaded with water for soaking and drying.

[0097] The fifth aspect is a method for preparing fiberboard based on any one of the first to fourth aspects. In the fifth aspect, the plant is a palm tree.

[0098] This aspect enables the efficient use of resources.

[0099] The sixth aspect is a compressed material for preparing fiberboard, wherein the compressed material is obtained by compressing a mixture comprising a milled product of plants and a water-soluble boron compound.

[0100] When using compressed materials based on this aspect for preparing fiberboard, water-soluble boron compounds can be present not only in the surface layer of the fiberboard but also in the fiberboard itself, thereby preparing fiberboard with long-term mite-proof properties.

[0101] The seventh aspect is a compressed material for preparing fiberboard based on the sixth aspect. In the seventh aspect, the water-soluble boron compound comprises at least one type of compound selected from the group consisting of boric acid, borax, disodium octaborate tetrahydrate, and sodium polyborate.

[0102] This aspect allows for further improvement in the mite-proof properties of fiberboard.

[0103] The eighth aspect is a compressed material for preparing fiberboard based on the sixth or seventh aspect. In the eighth aspect, the mixture further comprises a silicate compound.

[0104] This aspect inhibits the reduction of anti-mite properties, even when the fiberboard is repeatedly cyclically loaded with water for soaking and drying.

[0105] The ninth aspect is a compression material for preparing fiberboard based on the eighth aspect. In the ninth aspect, the amount of silicate compound added to the compression material is greater than or equal to 40 parts by mass and less than or equal to 60 parts by mass relative to 1 part by mass of boron in the water-soluble boron compound.

[0106] This further inhibits the reduction of anti-mite properties, even when the fiberboard is repeatedly cyclically loaded with water for soaking and drying.

[0107] The tenth aspect is a compressed material for preparing fiberboard based on any one of aspects six through nine. In the tenth aspect, the plant is a palm tree.

[0108] This aspect enables the efficient use of resources.

[0109] Example

[0110] The present invention will now be described in detail with reference to the embodiments. Note that the present invention is not limited to the following embodiments.

[0111] 1. Sample

[0112] (Comparative Example (Blank Sample))

[0113] First, the milled product of the plant (oil palm trunk) was steamed for 10 minutes at 150°C and 100% RH to separate the fibers, thereby obtaining wood fibers. Then, an adhesive (MDI) was added to the wood fibers, and the wood fibers were molded to obtain a mat-like molded product. The amount of adhesive added was 3% by mass.

[0114] Then, the pad-shaped molded product was pressed at 4.9 MPa for 1 minute while being heated at 200°C.

[0115] Therefore, a fiberboard with a thickness of 2 mm is obtained.

[0116] (Refer to Example 1)

[0117] After drying the milled product of the plant (oil palm trunk), the milled product is compressed to obtain a compressed material with a specific gravity of 0.61 and a water content of 9% by mass. The compressed material is then steamed at 150°C and 100% RH for 10 minutes, and fiber separation is performed to obtain wood fibers. A water-soluble boron compound (an aqueous solution of sodium polyborate manufactured by Soufa inc.) is added to the wood fibers, mixed, and then dried. The amount of water-soluble boron compound added to the wood fibers is 0.18% by mass of the amount of boron in the water-soluble boron compound.

[0118] Then, binder (MDI) is added to the wood fibers, and the wood fibers are molded to obtain a mat-like molded product. The amount of binder added is 3% by mass.

[0119] Then, the pad-shaped molded product was pressed at 4.9 MPa for 1 minute while being heated at 200°C.

[0120] Therefore, a fiberboard with a thickness of 2 mm is obtained.

[0121] (Example 1)

[0122] A water-soluble boron compound (an aqueous solution of sodium polyborate manufactured by Soufa inc.) was added to the ground product of the plant (oil palm trunk), and then dried to obtain a mixture. The mixture was then compressed to obtain a compressed material with a specific gravity of 0.61 and a water content of 9% by mass. The amount of water-soluble boron compound added to the mixture was 0.18% by mass of the amount of boron in the water-soluble boron compound.

[0123] Then, the compressed material is steamed for 10 minutes at 150°C and 100% RH, and fiber separation is performed to obtain wood fibers.

[0124] Then, binder (MDI) is added to the wood fibers, and the wood fibers are molded to obtain a mat-like molded product. The amount of binder added is 3% by mass.

[0125] Then, the pad-shaped molded product was pressed at 4.9 MPa for 1 minute while being heated at 200°C.

[0126] Therefore, a fiberboard with a thickness of 2 mm is obtained.

[0127] (Refer to Example 2)

[0128] Except that the amount of water-soluble boron compound added was changed to 0.13% by mass, a fiberboard with a thickness of 2 mm was obtained in a manner similar to that of Reference Example 1.

[0129] (Example 2)

[0130] Except that the amount of water-soluble boron compound added was changed to 0.13% by mass, a fiberboard with a thickness of 2 mm was obtained in a manner similar to that in Example 1.

[0131] (Refer to Example 3)

[0132] Except that the amount of water-soluble boron compound added was changed to 0.09% by mass, a fiberboard with a thickness of 2 mm was obtained in a manner similar to that of Reference Example 1.

[0133] (Example 3)

[0134] Except that the amount of water-soluble boron compound added was changed to 0.09% by mass, a fiberboard with a thickness of 2 mm was obtained in a manner similar to that in Example 1.

[0135] (Example 4)

[0136] A water-soluble boron compound (boric acid) and a silica compound (sodium silicate) were added to a ground product of plant material (oil palm trunk), which was then dried to obtain a mixture. The mixture was then compressed to obtain a compressed material with a specific gravity of 0.61 and a water content of 9% by mass. The amount of water-soluble boron compound added to the mixture was 0.10% by mass of the boron content in the water-soluble boron compound. The amount of silica compound added was 40 times the mass of the boron content in the water-soluble boron compound.

[0137] Then, the compressed material is steamed for 10 minutes at 150°C and 100% RH, and fiber separation is performed to obtain wood fibers.

[0138] Then, binder (MDI) is added to the wood fibers, and the wood fibers are molded to obtain a mat-like molded product. The amount of binder added is 3% by mass.

[0139] Then, the pad-shaped molded product was pressed at 4.9 MPa for 1 minute while being heated at 200°C.

[0140] Therefore, a fiberboard with a thickness of 2 mm is obtained.

[0141] (Example 5)

[0142] Except that the amount of water-soluble boron compound added was changed to 0.20% by mass, a fiberboard with a thickness of 2 mm was obtained in a manner similar to that in Example 4.

[0143] (Example 6)

[0144] Except for using Japanese cedar instead of oil palm trunk as the plant, using borax instead of boric acid as the water-soluble boron compound, and changing the amount of water-soluble boron compound added to 0.3% by mass, a fiberboard with a thickness of 2 mm was obtained in a manner similar to that in Example 4.

[0145] (Example 7)

[0146] Except for using calcium silicate instead of sodium silicate as the silicate compound and changing the amount of water-soluble boron compound added to 0.45% by mass, a fiberboard with a thickness of 2 mm was obtained in a manner similar to that in Example 4.

[0147] (Example 8)

[0148] Except for using sodium polyborate instead of boric acid as the water-soluble boron compound, and changing the amount of silica compound added to 50 times the mass of boron in sodium polyborate, a fiberboard with a thickness of 2 mm was obtained in a manner similar to that in Example 4.

[0149] (Example 9)

[0150] Except for using disodium tetraborate octaborate (DOT) instead of boric acid as the water-soluble boron compound, and changing the amount of silica compound added to 60 times the mass of boron in disodium tetraborate octaborate, a fiberboard with a thickness of 2 mm was obtained in a manner similar to that in Example 4.

[0151] (Example 10)

[0152] Except that no silica compound was used, a fiberboard with a thickness of 2 mm was obtained in a manner similar to that of Example 4.

[0153] (Example 11)

[0154] Except that the amount of silica compound added was changed to 30 times the mass of boron in the water-soluble boron compound, a fiberboard with a thickness of 2 mm was obtained in a manner similar to that in Example 4.

[0155] (Example 12)

[0156] Except that the amount of water-soluble boron compound added was changed to 0.55% by mass, a fiberboard with a thickness of 2 mm was obtained in a manner similar to that in Example 4.

[0157] (Sample size)

[0158] Cut the fiberboard of each of the comparative examples, reference examples 1 to 3 and examples 1 to 12 to obtain a sample with a size of 45 mm in length × 45 mm in width × 2 mm in height.

[0159] 2. Testing

[0160] (1) Examples 1 to 3, Reference Examples 1 to 3 and Comparative Examples

[0161] (Anti-mite properties)

[0162] According to JIS L 1920 "Testing methods for efficacy against house dust mite of textiles", a repellency test (petition dish method) was conducted.

[0163] The proliferation inhibition rate is classified based on the following evaluation criteria, and the mite-proof properties are evaluated.

[0164] The test results are shown in Table 1.

[0165] <<Evaluation Criteria>>

[0166] A: The proliferation inhibition rate is higher than or equal to 50%.

[0167] B: The proliferation inhibition rate is higher than or equal to 25% and lower than 50%.

[0168] C: The proliferation inhibition rate is less than 25%.

[0169]

[0170] In each of Examples 1 to 3 and Reference Examples 1 to 3, a water-soluble boron compound was added. Conversely, in the comparative examples, no water-soluble boron compound was added (no additives).

[0171] Therefore, compared with the comparative examples in which no water-soluble boron compound was added, Examples 1 to 3 and Reference Examples 1 to 3, each of which contained a water-soluble boron compound, exhibited excellent long-term anti-mite properties.

[0172] Furthermore, in each of Examples 1 to 3, a water-soluble boron compound was added to the milled plant product (pre-loading) prior to the steaming and fiber separation steps. Therefore, the water-soluble boron compound was subjected to high temperature and high humidity during the steaming and fiber separation steps.

[0173] Conversely, in Reference Examples 1 to 3, the water-soluble boron compound was added to the lignocellulose after the steaming and fiber separation steps (post-loading). Therefore, the water-soluble boron compound was not subjected to high temperature and high humidity.

[0174] When each of Examples 1 to 3, which are preloaded with a water-soluble boron compound, is compared with each of Reference Examples 1 to 3, which are postloaded with a water-soluble boron compound, the anti-mite properties of Examples 1 to 3 and Reference Examples 1 to 3 are both excellent. Therefore, it can be seen that the water-soluble boron compound is not easily decomposed even when exposed to high temperature and high humidity.

[0175] (2) Examples 4 to 12 and Comparative Examples

[0176] (Anti-mite properties)

[0177] According to JIS K 1571:2010 "wood preservatives—performance requirements and their test methods for determining effectiveness," the anti-mite properties were evaluated both with and without performing the following cyclic tests. The anti-mite properties were evaluated as explained. The test results are shown in Table 2. Note that specific values, such as proliferation inhibition rate, are omitted in Table 2.

[0178] <<Loop Test>>

[0179] Each sample was placed in water at 25°C for 8 hours, and then dried at 60°C for 16 hours. This process was repeated 10 times.

[0180] (Peel strength)

[0181] Each sample was bonded to a metal block using an epoxy-based adhesive, and the metal block was peeled off at a speed of 2 mm / min to measure the peel strength. The measured values ​​were classified and the peel strength was evaluated based on the following evaluation criteria. The test results are shown in Table 2.

[0182] <<Evaluation Criteria>>

[0183] A: Peel strength is greater than or equal to 0.65 MPa.

[0184] B: Peel strength is less than 0.65 MPa.

[0185] [Table 2]

[0186]

[0187] *1. Amount of boron added (mass%) of water-soluble boron compounds in the compression material.

[0188] *2 Water-soluble boron compounds may or may not be treated with high temperature and high humidity.

[0189] *3 The amount of boron added relative to 1 part by mass in the compressed material is the same as the amount (parts by mass) of silica compound added.

[0190] *4 Test involving repeated cycles of water immersion and drying.

[0191] *5 is the same as the comparative example in Table 1.

[0192] When comparing Example 10, in which no silica compound was added, with Examples 4 to 9, 11, and 12, in which each of them was added with a silica compound, it can be seen that the anti-mite properties of each of Examples 4 to 9, 11, and 12 are unlikely to decrease even when subjected to repeated cycles of soaking and drying with water.

Claims

1. A method for preparing fiberboard, the method comprising: The compression step involves compressing a mixture containing ground plant material and a water-soluble boron compound to obtain a compressed material. The compressed material is subjected to steaming and fiber separation steps to obtain wood fibers. In the molding step, an adhesive is added to the wood fibers, and then the wood fibers are molded to obtain a mat-shaped molded product; as well as The hot pressing step involves pressing the pad-shaped molded product while heating it, wherein... The amount of boron added to the water-soluble boron compound in the compressed material is greater than or equal to 0.05% by mass and less than or equal to 0.5% by mass.

2. The method according to claim 1, wherein The water-soluble boron compound includes at least one type of compound selected from the following: boric acid, borax, disodium octaborate tetrahydrate, and sodium polyborate.

3. The method according to claim 1, wherein The mixture also contains silica compounds.

4. The method according to claim 3, wherein The amount of the silica compound added to the compressed material is greater than or equal to 40 parts by mass and less than or equal to 60 parts by mass relative to 1 part by mass of boron in the water-soluble boron compound.

5. The method according to any one of claims 1 to 4, wherein The plant in question is a palm family (palm family).

6. Compressed material used in the preparation of fiberboard, The compressed material is obtained by compressing a mixture containing a ground plant product and a water-soluble boron compound. The boron content of the water-soluble boron compound in the compressed material is greater than or equal to 0.05% by mass and less than or equal to 0.5% by mass.

7. The compression material according to claim 6, wherein... The water-soluble boron compound includes at least one type of compound selected from the following: boric acid, borax, disodium octaborate tetrahydrate, and sodium polyborate.

8. The compression material according to claim 6, wherein The mixture also contains silica compounds.

9. The compression material according to claim 8, wherein The content of the silica compound in the compressed material is greater than or equal to 40 parts by mass and less than or equal to 60 parts by mass relative to 1 part by mass of boron in the water-soluble boron compound.

10. The compression material according to any one of claims 6 to 9, wherein The plant in question is a palm family (palm family).

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