Board material and production method for board material

Abstract

This board material (1) is a slab-shaped body that has a prescribed thickness and density and comprises charred seed husks (2), wood fibers (3) in an amount that makes the total as added to the seed husks (2) 1–50 wt%, and a binding agent (4) that is principally at least one of cellulose nanofibers, bacterial cellulose, and lignocellulose nanofibers in an amount of 1–20 wt% relative to the total weight of the seed husks (2) and the wood fibers (3), the seed husks (2), the wood fibers (3), and the binding agent (4) being hardened in a mixed, dispersed state. The present invention provides a novel board material that uses natural starting materials, has heat insulation performance, and is particularly suited to use as a heat insulation material.

Description

Board material and method for manufacturing the same

[0001] The present invention relates to a board material and a method for manufacturing the board material, and more particularly to a board material suitable for use as a thermal insulating material and a method for manufacturing the board material.

[0002] In recent years, glass wool has been widely used as a thermal insulating material for buildings, but there are regions and countries where it is difficult to obtain glass wool, and there is also a demand to reuse natural materials that have been discarded until now in order to realize a sustainable society, so thermal insulating materials made from natural materials are being reconsidered.Board materials made from natural materials and that can be used as thermal insulating materials are disclosed in, for example, Patent Document 1 and Patent Document 2.

[0003] Patent Document 1 discloses an insulating material made from burnt rice husks, which is produced by burning rice husks to produce burnt rice husks (rice husk charcoal), adding a binder (adhesive) to the burnt rice husk raw material, and then placing the burnt rice husks in a mold and molding them under pressure.

[0004] Patent Document 2 discloses a composite building material having numerous voids, which is obtained by adding a material containing an inorganic binder to a natural fiber material (such as rice husks) and then firing the resulting molded body, and which is made of ash and charcoal of the natural fiber material and an inorganic binder.

[0005] JP 2001-271435 A JP 2001-181068 A

[0006] There is always a desire for new board materials that can be used as an alternative to glass wool, have insulating properties, and are made from natural materials.

[0007] In view of the above, an object of the present invention is to provide a new board material having heat insulating properties and made from natural materials, particularly a new board material suitable for use as a heat insulating material. Another object of the present invention is to provide a method for manufacturing such a new board material.

[0008] In order to solve the above problems, the board material of the present invention comprises charcoalized seed shells, wood fibers blended so that the content thereof is 1% or more and 50% or less of the combined weight of the seed shells, and a binder whose main component is at least one of cellulose nanofibers, bacterial cellulose, and lignocellulose nanofibers, blended in an amount of 1% or more and 20% or less of the combined weight of the seed shells and wood fibers, and is characterized by being a board-shaped body of a predetermined thickness and a predetermined density in which the seed shells, wood fibers, and binder are solidified in a dispersed and mixed state.

[0009] This board material has a thickness of 3 mm or more and a density of 0.35 g / cm 3 or less, and the thermal conductivity is 0.1 W / m·K or less.

[0010] In this board material, the seed husks are at least one of rice husks, wheat husks, buckwheat husks and soybean husks that are charcoalized in an uncrushed or crushed state.

[0011] In addition, in this board material, the wood fibers are obtained from at least one of conifers, broad-leaved trees, mulberry, mitsumata, gampi, hemp, bagasse, esparto, bamboo, kenaf, and flax, and have a diameter of 0.01 mm or more and a length of 50 mm or less.

[0012] The board material may further contain an insect repellent.

[0013] The method for manufacturing a board material according to the present invention comprises the following steps: a mixing step of adding and dispersing carbonized seed shells, wood fiber blended so that the content of the wood fiber combined with the seed shells is 1% to 50% of the combined weight of the seed shells, and a binder whose main component is at least one of cellulose nanofiber, bacterial cellulose, and lignocellulose nanofiber, blended in an amount of 1% to 20% by weight of the combined weight of the seed shells and wood fiber; a wet papermaking step of using a mesh material to remove moisture from the raw material containing the seed shells, wood fiber, and binder that have been dispersed and mixed in water in the mixing step, thereby extracting the moist fiber material; a cold-pressing step of sandwiching the moist fiber material extracted in the wet papermaking step between boards and applying pressure to further remove moisture and form it into a plate-like body; a drying step of drying the plate-like body formed in the cold-pressing step at a high temperature to solidify the seed shells, wood fiber, and binder in a dispersed and mixed state; and a curing step of curing the plate-like body solidified in the drying step until it reaches a stable state with a predetermined thickness and density.

[0014] In this method of manufacturing board materials, in the curing process, the thickness is 3 mm or more and the density is 0.35 g / cm ３ The curing is carried out so that the temperature is stable at 0.10 W / m·K or less and the thermal conductivity is stable at 0.10 W / m·K or less.

[0015] In this method for manufacturing the board material, it is preferable to use at least one of rice husks, wheat husks, buckwheat husks, and soybean husks, which are charcoalized either uncrushed or crushed.

[0016] In this method for manufacturing board material, the wood fibers used should be those obtained from at least one of conifers, broad-leaved trees, paper mulberry, mitsumata, gampi, hemp, bagasse, esparto, bamboo, kenaf, and flax, and have a diameter of 0.01 mm or more and a length of 50 mm or less.

[0017] In this method for manufacturing a board material, it is also preferable to further blend an insect repellent in the mixing step and disperse and mix it.

[0018] In the method for manufacturing this board material, in the mixing step, water is added so that the concentration of charcoal and fiber is 1% or more and 2% or less, and the seed husks, wood fiber, and binder are mixed by rotating the mixing screw at a rotation speed of 500 rpm or more and 1000 rpm or less for 10 minutes or more and 30 minutes or less.

[0019] In this method of manufacturing a board material, it is preferable to use a wire mesh having a mesh size of 50 mesh or more and 100 mesh or less as the mesh material in the wet papermaking process.

[0020] In this method for manufacturing a board material, the cold pressing step is preferably performed at a pressure of 0.2 MPa or more and 0.6 MPa or less for 1 minute or more and 5 minutes or less.

[0021] In this method for manufacturing a board material, the drying step is preferably carried out at a temperature of 105° C. or higher and 110° C. or lower for 24 hours or longer and 48 hours or shorter.

[0022] In this method of manufacturing a board material, the curing step is preferably carried out in an environment with a temperature of 20° C. to 25° C. and a humidity of 60% to 70% for 7 to 10 days.

[0023] According to the present invention, it is possible to provide a new board material made of natural material having heat insulating properties, particularly a new board material suitable for use as a heat insulating material, and to manufacture such a new board material made of natural material.

[0024] It is a perspective view showing a board material according to an embodiment. It is a flowchart showing a method for manufacturing a board material according to an embodiment. It is an explanatory diagram of each manufacturing step in the method for manufacturing a board material according to an embodiment.

[0025] Fig. 1 is a perspective view showing a board material 1 according to an embodiment, Fig. 2 is a flowchart showing a manufacturing method of the board material 1, and Fig. 3 is an explanatory diagram of each step in the manufacturing method. The board material 1 will be described below with reference to these figures.

[0026] As shown in Figure 1, the board material 1 to which the present invention is applied comprises, as its main raw materials, charcoalized seed shells 2, wood fibers 3 derived from woody plants, and a binder 4 that binds the seed shells 2 and the wood fibers 3 (functioning as a binder), and the raw materials including these are solidified in a dispersed mixed state to form a plate-like body with a predetermined thickness and density. If the board material 1 is thinner than 3 mm, it becomes fragile and difficult to use, and if it is thicker than 100 mm, it becomes difficult to install and becomes heavy, which may result in high costs due to safety confirmation by structural calculations and load countermeasures such as reinforcement. Therefore, the board material 1 is configured to have a thickness of 3 mm or more and 100 mm or less. Furthermore, the board material 1 has a density of 0.03 g / cm, which is the same as that of wood fiber or glass wool. ３ However, if the board is too heavy, workability will be poor and the board may become too heavy, which may lead to increased costs due to safety confirmation through structural calculations and countermeasures against loads such as reinforcement. ３ Preferably, it is 0.35 g / cm, which is lighter than cedar. ３ The board material 1 is arranged on the roof, wall, floor, etc., and is arranged with a thermal conductivity of 0.10 W / m K or less, which is less than 70% of the thermal conductivity of plywood, 0.16 W / m K, so as to provide a heat insulating effect when arranged. In this way, the board material 1 has a thickness of 3 mm or more and a density of 1 g / cm ３ The board material 1 is configured as a plate-like body having a thermal conductivity of 0.10 W / m K or less and a thermal conductivity of 0.10 W / m K or less, and can be used not only as a heat insulating material but also as a substitute for bubble cushioning material. As an example preferable for use as a heat insulating material, the board material 1 has a square shape of 180 mm x 180 mm in plan view, a thickness of 20 mm or 30 mm, and a density of 0.2 g / cm ３ and the thermal conductivity can be configured as a plate-like body having a thermal conductivity of 0.05 to 0.06 W / m·K.

[0027] As an example, the seed husks 2 are charcoalized uncrushed or crushed rice husks. Alternatively, charcoalized wheat husks, buckwheat husks, or soybean husks are also suitable as the seed husks.

[0028] As an example, the wood fibers 3 are obtained by loosening coniferous wood and forming it into fibers having a diameter of 0.01 mm or more and a length of 50 mm or less, preferably a diameter of 0.02 to 0.03 mm and a length of 1 to 5 mm. The wood fibers 3 are blended in at a content of 1% to 50% of the combined weight of the wood fibers and the seed shells 2 (seed shells 2:wood fibers 3 = 99:1 to 50:50), preferably 25 to 35% (seed shells 2:wood fibers 3 = 75:25 to 65:35). Wood fibers 3 may also be obtained from at least one of broad-leaved trees, paper mulberry, mitsumata, gampi, hemp, bagasse, esparto, bamboo, kenaf, and flax.

[0029] The binder 4 is primarily composed of cellulose nanofibers (CNF). Alternatively, the binder 4 may be primarily composed of cellulose nanofibers containing bacterial cellulose (BC). Alternatively, the binder 4 may be primarily composed of lignocellulose nanofibers (LCNF), which contain lignin and hemicellulose, other major wood components, in addition to cellulose. The binder 4 is blended in at a weight ratio of 1% or more of the combined weight of the seed shells 2 and wood fibers 3. The binder 4 functions as a binder binding the seed shells 2 and wood fibers 3, and a larger amount is preferred because a solid plate-like body is formed. However, because the binder 4 is relatively expensive, it is blended in at a weight ratio of 20% or less of the combined weight of the seed shells 2 and wood fibers 3 to avoid excessively high costs for practical use.

[0030] The board material 1 made from such raw materials is primarily made of natural materials that are available in most regions, and is lightweight and has heat insulating properties, making it suitable for use as a heat insulating material or a cushioning material. Next, a method for manufacturing the board material 1 will be described in detail.

[0031] As shown in FIG. 2, the board material 1 is manufactured through a preparation step ST1, a mixing step ST2, a wet paper-making step ST3, a cold-pressing step ST4, a drying step ST5, and a curing step ST6.

[0032] In the preparation step ST1, the above-described seed husks 2, wood fiber 3, and binder 4 are prepared as raw materials. Specifically, the seed husks 2 are prepared by charcoaling rice husks, wheat husks, buckwheat husks, or soybean husks, either uncrushed or crushed. The wood fiber 3 is prepared from at least one of coniferous trees, broad-leaved trees, paper mulberry, Mitsumata, gampi, hemp, bagasse, esparto, bamboo, kenaf, and flax, and has a diameter of 0.01 mm or more and a length of 50 mm or less. The binder 4 is prepared by primarily containing at least one of cellulose nanofibers, bacterial cellulose, and lignocellulose nanofibers. Cellulose nanofibers containing bacterial cellulose may also be prepared as the binder 4.

[0033] In the mixing step ST2, water is added to disperse and mix the charcoalized seed shells 2 prepared in the preparation step ST1, wood fibers 3 blended so that the content is 1% to 50% of the combined weight of the seed shells 2, and binder 4 blended in an amount of 1% to 20% by weight of the combined weight of the seed shells 2 and wood fibers 3. Specifically, in the mixing step ST2, as shown in Figure 3(a), the seed shells 2, wood fibers 3, and binder 4 prepared in the preparation step ST1 are blended in a predetermined ratio and placed in a stirring vessel, water is added so that the charcoal and fiber concentrations are 1% to 2%, preferably 1.5%, and the seed shells 2, wood fibers 3, and binder 4 are stirred using the stirring screw 11, which is rotated at a speed of 500 to 1000 rpm for 10 minutes to 30 minutes, preferably 10 minutes at a speed of 750 rpm.

[0034] In the wet paper-making step ST3, the raw material containing the seed husks 2, wood fibers 3, and binder 4 dispersed and mixed in water in the mixing step ST2 is passed through a mesh material to remove moisture and form a wet fibrous material. Specifically, in the wet paper-making step ST3, as shown in Figure 3(b), for example, a required amount of the seed husks 2, wood fibers 3, and binder 4 mixed in the mixing step ST2 is poured into a frame 12 having an inner dimension of 180 mm x 180 mm and a predetermined height, while removing moisture using a wire mesh 13 with a mesh size of 50 mesh or more and 100 mesh or less, preferably 100 mesh, placed under the frame 12, to form a wet fibrous material of a predetermined thickness.

[0035] In the cold-pressing step ST4, the wet fibrous material formed in the wet paper-making step ST3 is sandwiched between plates and pressurized, and the moisture is further removed and molded into a plate-like body. Specifically, in the cold-pressing step ST4, as shown in Fig. 3(c), for example, a 180 mm x 180 mm frame is cut out using distance bars 14 of a height corresponding to the thickness of the final product, the wet fibrous material formed in the wet paper-making step ST3 is placed inside the frame and sandwiched between 100-mesh wire meshes 13 from above and below, and the wire meshes 13 are further sandwiched between iron plates 15 from above and below, and the iron plates 15 are pressed vertically inward at a pressure of 0.2 MPa to 0.6 MPa for 1 minute to 5 minutes, preferably 0.6 MPa, to further remove moisture and mold into a plate-like body.

[0036] In the drying step ST5, the plate-shaped body formed in the cold-pressing step ST4 is dried at a high temperature to solidify the seed husks 2, wood fibers 3, and binder 4 in a dispersed and mixed state. Specifically, in the drying step ST5, as shown in Fig. 3(d), for example, the fiber material from which moisture has been further removed in the cold-pressing step ST4, which is surrounded by distance bars 14 and sandwiched from above and below between wire mesh 13 and iron plate 15, is held in a vice 16 with iron plate 15 sandwiched between them, and dried in this state at a temperature of 105°C to 110°C for 24 to 48 hours, preferably at 105°C for 24 hours, to solidify the seed husks 2, wood fibers 3, and binder 4 in a dispersed and mixed state.

[0037] In the curing step ST6, the plate-shaped body solidified in the drying step ST5 is cured until it reaches a stable state with a predetermined thickness and a predetermined density. ３ The curing is performed so that the temperature is stable at 0.10 W / m K or less and the thermal conductivity is stable at 0.10 W / m K or less. Specifically, in the curing step ST6, as shown in FIG. 3( e), for example, the vice 16, iron plate 15, and wire mesh 13 are removed, and the uncured board material that has solidified into a plate shape is removed from the formwork formed by the distance bars 14, arranged in a predetermined position (for example, upright), and cured for 7 to 10 days in an environment where the temperature is 20° C. to 25° C. and the humidity is 60% to 70%, preferably for 7 days in an environment where the temperature is 20° C. and the humidity is 65%. In this way, the board material 1 is manufactured, and performance evaluation and the like are performed before completion.

[0038] The board material 1 and the method for manufacturing the board material 1 of the embodiment include, as raw materials, charcoalized seed shells 2, wood fibers 3, and a binder 4 primarily composed of at least one of cellulose nanofibers, bacterial cellulose, and lignocellulose nanofibers. The binder 4 acts as a binder, allowing the seed shells 2 and wood fibers 3 to solidify in a mixed state to a thickness of 3 mm or more, resulting in a board material not previously available. This board material 1 is primarily made from fibers such as seed shells 2 and wood fibers 3. As a result, the board material 1 contains a large amount of air between the fibers, resulting in lightweight and insulating properties. In addition to the insect repellent properties of the cellulose nanofibers, bacterial cellulose, or lignocellulose nanofibers in the binder 4, the charcoalized seed shells 2 make the board material 1 less susceptible to termite infestation. Furthermore, because the board material 1 is primarily made from natural materials available in most regions, such as the seed shells 2 and wood fibers 3, it can be manufactured locally even in areas where glass wool is difficult to obtain. Therefore, if the board material 1 of the embodiment is constructed as described above, it will be a new board material made from natural materials and having heat insulating properties. Also, if the board material 1 of the embodiment is manufactured using the manufacturing method described above, it will be possible to manufacture a new board material made from natural materials and having heat insulating properties.

[0039] Although the present invention has been described based on the above embodiment, the present invention is not limited to the above embodiment and can be embodied in various forms without departing from the spirit of the present invention, and for example, the following modifications are also possible.

[0040] (1) The specific planar size, thickness, shape, temperature, time, speed, pressure, ratio, physical property values, orientation or posture during manufacturing, materials and types of equipment and tools used in manufacturing, etc. described in the above embodiments are examples and can be changed within the scope that does not impair the effects of the present invention.

[0041] (2) In the above-described embodiment, the board material 1 was constructed using only the seed shells 2, wood fibers 3, and binder 4 as raw materials, but the present invention is not limited to this. For example, additives such as insect repellents (e.g., termite repellents) may be blended depending on the intended use. When manufacturing a board material blended with additives such as insect repellents, the additives may be blended by using any of the following methods: mixing the additives with the seed shells, wood fibers, and binder in a mixing step; impregnating the wood fibers or seed shells with the additives before the mixing step; or spraying the additives onto the molded board after any step after the cold-pressing step.

[0042] (3) In the above embodiment, the board material 1 is described as being used primarily as a heat insulating material for buildings, but the present invention is not limited to this. As mentioned above, the board material 1 may be used as a substitute for bubble cushioning material or for other purposes.

[0043] Next, as an example, two specimens (hereinafter referred to as "first specimen" and "second specimen") of board material to which the present invention is applied were manufactured, and the performance thereof was evaluated as follows.

[0044] For the first test piece, rice husks that had been charcoalized and wood fibers made from coniferous trees in the form of fibers with a diameter of 0.02 to 0.03 mm and a length of 1 to 5 mm were mixed in a ratio of 7:3, and a binder made of cellulose nanofiber was further added at a concentration of 10% by weight. These were then mixed and solidified to a thickness of 20 mm to produce a board material. As a result of evaluating the performance of this first test piece, it was found that the density was 0.2 g / cm ３ The thermal conductivity was 0.0585 W / m·K, and it was found that the effect as a heat insulating material was sufficiently obtained.

[0045] For the second test piece, rice husks that had been charcoalized and wood fibers made from coniferous trees in the form of fibers with a diameter of 0.02 to 0.03 mm and a length of 1 to 5 mm were mixed in a ratio of 7:3, and a binder made of cellulose nanofibers was further added at a concentration of 10% by weight. These were then mixed and solidified to a thickness of 30 mm to produce a board material. As a result of evaluating the performance of this second test piece, it was found that the density was 0.2 g / cm ３ The thermal conductivity was 0.0531 W / m·K, and it was found that the effect as a heat insulating material was sufficiently obtained.

Claims

1. A board material comprising: charcoalized seed shells; wood fibers mixed in such that the content thereof is 1% or more and 50% or less of the combined weight of the seed shells; and a binder whose main component is at least one of cellulose nanofibers, bacterial cellulose, and lignocellulose nanofibers, mixed in an amount of 1% or more and 20% or less of the combined weight of the seed shells and the wood fibers; and characterized in that the seed shells, the wood fibers, and the binder are solidified in a dispersed and mixed state in a board-like body having a specified thickness and density.

2. The board material according to claim 1, wherein the thickness is 3 mm or more and 100 mm or less, and the density is 1 g / cm 3 and a thermal conductivity of the board material is 0.1 W / m·K or less.

3. A board material according to claim 1, wherein the seed husks are at least one of rice husks, wheat husks, buckwheat husks and soybean husks, which are charcoalized in an uncrushed or crushed state.

4. A board material according to claim 1, wherein the wood fibres are obtained from at least one of conifers, broad-leaved trees, paper mulberry, mitsumata, gampi, hemp, bagasse, esparto, bamboo, kenaf and flax, and have a diameter of 0.01 mm or more and a length of 50 mm or less.

5. The board material according to claim 1, further comprising an insect repellent.

6. A mixing process in which charcoalized seed shells, wood fibers that are blended so that the content of the seed shells combined with the wood fibers is 1% or more and 50% or less of the combined weight of the seed shells, and a binder whose main component is at least one of cellulose nanofibers, bacterial cellulose, and lignocellulose nanofibers, which is blended in an amount of 1% or more and 20% or less of the combined weight of the seed shells and the wood fibers, are added with water to disperse and mix them; a wet papermaking process in which the raw material containing the seed shells, the wood fibers, and the binder that have been dispersed and mixed in water in the mixing process is papered using a mesh material to remove moisture and extract the moist fiber material; a cold pressing process in which the moist fiber material extracted in the wet papermaking process is sandwiched between plates and pressed, and further moisture is removed and formed into a plate-shaped body; and a drying process in which the plate-shaped body formed in the cold pressing process is dried at high temperature to solidify the seed shells, the wood fibers, and the binder in a dispersed and mixed state. a curing step of curing the plate-like body solidified in the drying step until it becomes stable with a predetermined thickness and a predetermined density.

7. The method for manufacturing a board material according to claim 6, wherein the curing step is carried out to obtain a board material having a thickness of 3 mm or more and a density of 1 g / cm ３ and a method for manufacturing a board material in which the board is cured so that the thermal conductivity is stable at 0.10 W / m K or less.

8. A method for manufacturing a board material as claimed in claim 6, wherein the seed husks used are at least one of rice husks, wheat husks, buckwheat husks and soybean husks, either uncrushed or charcoalized in a crushed state.

9. A method for manufacturing a board material as claimed in claim 6, wherein the wood fibres are obtained from at least one of conifers, broad-leaved trees, paper mulberry, mitsumata, gampi, hemp, bagasse, esparto, bamboo, kenaf and flax, and have a diameter of 0.01 mm or more and a length of 50 mm or less.

10. A method for manufacturing a board material as set forth in claim 6, wherein the mixing step further comprises compounding, dispersing and mixing an insect repellent.

11. A method for manufacturing a board material as claimed in any one of claims 6 to 10, wherein in the mixing step, water is added so that the concentration of charcoal and fiber is 1% or more and 2% or less, and a mixing screw is used to mix the seed shells, the wood fiber, and the binder by rotating the mixing screw at a rotation speed of 500 rpm or more and 1000 rpm or less for 10 minutes or more and 30 minutes or less.

12. A method for manufacturing a board material according to any one of claims 6 to 10, wherein in the wet papermaking process, a wire mesh having a mesh size of 50 mesh or more and 100 mesh or less is used as the mesh material.

13. A method for manufacturing a board material according to any one of claims 6 to 10, wherein in the cold pressing step, pressure is applied at a pressure of 0.2 MPa or more and 0.6 MPa or less for 1 minute or more and 5 minutes or less.

14. A method for manufacturing a board material according to any one of claims 6 to 10, wherein in the drying step, the board material is dried at a temperature of 105°C or higher and 110°C or lower for 24 hours or longer and 48 hours or shorter.

15. A method for manufacturing a board material according to any one of claims 6 to 10, wherein the curing step involves curing the board for 7 to 10 days in an environment with a temperature of 20°C to 25°C and a humidity of 60% to 70%.

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