Molded article and method for manufacturing same

Abstract

This method for manufacturing a molded article comprises: a step for preparing a lignocellulose-containing solution obtained by dissolving a plant material containing lignocellulose in an organic acid; a step for mixing a pulverized product of the plant material containing lignocellulose with the lignocellulose-containing solution to obtain a mixture of the pulverized product; and a step for molding the solid content of the mixture to obtain a molded article. The mass ratio of the pulverized product of the plant material containing lignocellulose to the solid content of the lignocellulose-containing solution is 0.5:9.5 to 9.5:0.5, and the solid content of the mixture is substantially composed of a biomass-derived component.

Description

Molded article and method for manufacturing the same

[0001] This disclosure relates to molded articles and methods for manufacturing the same.

[0002] Traditionally, plant materials, such as wood, have been used in various applications, including building materials and furniture components. In particular, the use of high-quality wood is preferred for the surface of components due to its beautiful, luxurious appearance and pleasant feel; however, high-quality wood is generally expensive. Furthermore, the recent depletion of forest resources has made obtaining high-quality wood difficult. Additionally, wood is difficult to mold by pressure and requires cutting and processing.

[0003] Conventionally, techniques for bonding thin slices of wood to various substrates have been disclosed. For example, Japanese Utility Model Publication No. 5-35208 (Patent Document 1) proposes a decorative panel that expresses a more luxurious wood texture by carving different pseudo-vessel grooves into the surface of a wood-based panel without concealing its original surface vessel grooves. Japanese Patent Publication No. 5-50408 (Patent Document 2) discloses a decorative building material in which a wood-grain pattern is formed on the surface of a wood-based panel by pressing the surface of the wood-based panel to form a wood-grain-like uneven pattern and then coloring it, thereby giving the surface of the wood-based panel a luxurious feel. Japanese Patent Publication No. 8-60800 (Patent Document 3) proposes a composite wood column in which a rectangular prism-shaped core wood exists in the center, and a plate-shaped covering wood exists around this core wood, with the core wood and the covering wood being bonded together. Patent Document 3 discloses a technique for providing high-quality wood columns at low cost by using high-grade wood for the covering wood.

[0004] Japanese Patent Publication No. 2017-18543 (Patent Document 4) discloses a method for recovering old, large furniture made of solid wood, in which deteriorated wood is disassembled and taken apart, the solid wood surfaces of each piece are polished and painted, and then reassembled to create a furniture body. Japanese Patent Publication No. 2017-176992 (Patent Document 5) proposes a scratch repair painting method for repairing scratches on the surface of wood material. This method includes a putty application step, a surface leveling step, a hardening step, a surface polishing step, a sealer application step, a sealer removal step, and a coloring step. Japanese Patent No. 3956375 (Patent Document 6) discloses a method for repairing scratches on wood products, which includes a step of filling the scratched part of the wood product with a filler made of synthetic resin material, and a step of applying an instant adhesive and an instant adhesive hardening accelerator to the surface and surrounding area of ​​the filled part.

[0005] On the other hand, wood-based materials that do not use adhesives (binderless) are also being considered. For example, Japanese Patent Publication No. 2008-260238 (Patent Document 7) discloses a plant fiber molded body obtained by a matting process in which a mat containing plant fibers is formed, a steam treatment process in which the mat is exposed to steam at a temperature of 150°C or higher, and a molding process in which the steam-treated mat is shaped under pressure to obtain a molded body.

[0006] Japanese Patent Publication No. 2014-019033 (Patent Document 8) proposes an oil palm molded body obtained by stacking multiple oil palm sheets with their fiber directions intersecting each other, and then applying a compressive force perpendicular to the surface of the laminated oil palm sheets. Japanese Patent Publication No. 2018-64934 (Patent Document 9) discloses a laminated board derived from birch bark in which layers are fixed to each other by adhesive bonding generated by heat introduction.

[0007] In recent years, with the increasing severity of environmental pollution, pulp molds have attracted attention as a material that can help eliminate plastic. Pulp molds are paper molded products made by dissolving plant fibers (mainly recycled paper) in water, intertwining them, forming them in a mold, and then drying them. They are mainly used as packaging containers. Furthermore, molding techniques using thermoformed molds have been proposed to obtain thinner and more complex-shaped pulp molds. However, because pulp molds are made of paper, they are permeable to water and air, which presents challenges in their suitability for certain applications.

[0008] As a material that suppresses water permeability and breathability, Japanese Patent Publication No. 2000-309322 (Patent Document 10) discloses a water-resistant pulp molded container having a synthetic resin film layer laminated on one side of the pulp molded product, and a waterproof layer formed by laminating a synthetic resin film layer on the other side or by coating it with a waterproof paint.

[0009] Patent Document 1: Japanese Utility Model Publication No. 5-35208 Patent Document 2: Japanese Patent Publication No. 5-50408 Patent Document 3: Japanese Patent Publication No. 8-60800 Patent Document 4: Japanese Patent Publication No. 2017-18543 Patent Document 5: Japanese Patent Publication No. 2017-176992 Patent Document 6: Japanese Patent No. 3956375 Patent Document 7: Japanese Patent Publication No. 2008-260238 Patent Document 8: Japanese Patent Publication No. 2014-019033 Patent Document 9: Japanese Patent Publication No. 2018-64934 Patent Document 10: Japanese Patent Publication No. 2000-309322

[0010] The primary purpose of this disclosure is to provide a novel method for manufacturing molded articles composed substantially of biomass-derived components. Furthermore, this disclosure also aims to provide molded articles composed substantially of biomass-derived components that achieve both high mechanical strength and low density.

[0011] Through diligent research, the inventors of this disclosure have found that a method for producing a molded body is employed, comprising the steps of: preparing a lignocellulose-containing solution by dissolving lignocellulose-containing plant material in an organic acid; mixing pulverized lignocellulose-containing plant material with the lignocellulose-containing solution to obtain a mixture of the pulverized material; and molding the solid portion of the mixture to obtain a molded body. Furthermore, by setting the mass ratio of the pulverized lignocellulose-containing plant material to the solid portion of the lignocellulose-containing solution within a predetermined range, a molded body can be suitably produced that is substantially composed of biomass-derived components and achieves both high mechanical strength and low density.

[0012] In other words, we found that in a molded body using plant material containing lignocellulose, by including pulverized lignocellulose-containing plant material and solid components of a lignocellulose-containing solution in which the lignocellulose-containing plant material is dissolved in an organic acid, and by setting the mass ratio of the pulverized material to the solid components within a predetermined range, a molded body can be made that is substantially composed of biomass-derived components and achieves both high mechanical strength and low density.

[0013] This disclosure is an invention completed through further consideration based on these findings. Specifically, this disclosure provides inventions in the following embodiments.

[0014] (Method for manufacturing a molded body) A method for manufacturing a molded body comprising: a step of preparing a lignocellulose-containing solution obtained by dissolving a plant material containing lignocellulose in an organic acid; a step of mixing pulverized plant material containing lignocellulose with the lignocellulose-containing solution to obtain a mixture of the pulverized material; and a step of molding the solid portion of the mixture to obtain a molded body, wherein the mass ratio of the pulverized plant material containing lignocellulose to the solid portion of the lignocellulose-containing solution is 0.5:9.5 to 9.5:0.5, and the solid portion of the mixture is substantially composed of biomass-derived components.

[0015] (Molded body) A molded body comprising pulverized plant material containing lignocellulose and solid components of a lignocellulose-containing solution in which the lignocellulose-containing plant material is dissolved in an organic acid, wherein the mass ratio of the pulverized material to the solid components is 0.5:9.5 to 9.5:0.5, and the molded body is substantially composed of biomass-derived components.

[0016] This disclosure provides a novel method for manufacturing molded articles composed substantially of biomass-derived components. Furthermore, this disclosure provides molded articles that are substantially composed of biomass-derived components and achieve both high mechanical strength and low density.

[0017] The images shown are of the surface of the molded articles of Examples 1 and 2 and Comparative Examples 1 and 2, observed with a digital microscope (x50), the black and white converted versions of these images, and the formylation rate (%).

[0018] Each configuration and its combination in each embodiment is an example, and additions, omissions, substitutions, and other modifications can be made as appropriate without departing from the spirit of this disclosure. This disclosure is not limited by the embodiments.

[0019] In the numerical ranges described in stages in this disclosure, the upper or lower limit stated in one numerical range may be replaced with the upper or lower limit of another numerical range described in stages. Alternatively, the upper and lower limits, upper and lower limits, or lower and lower limits described separately may be combined to form numerical ranges. Furthermore, in the numerical ranges described in this disclosure, the upper or lower limit stated in one numerical range may be replaced with the values ​​shown in the examples.

[0020] Furthermore, unless otherwise noted, all test temperatures are room temperature (20°C ± 5°C), and weight percent refers to weight percentage, not mass concentration. Also, the unit of mass "t (ton)" refers to "metric ton."

[0021] [Method for Manufacturing a Molded Article] The method for manufacturing a molded article according to the present disclosure comprises the steps of: preparing a lignocellulose-containing solution by dissolving a plant material containing lignocellulose in an organic acid; mixing pulverized lignocellulose-containing plant material with the lignocellulose-containing solution to obtain a mixture of the pulverized material; and molding the solid portion of the mixture to obtain a molded article, wherein the mass ratio of the pulverized lignocellulose-containing plant material to the solid portion of the lignocellulose-containing solution is 0.5:9.5 to 9.5:0.5, and the solid portion of the mixture is substantially composed of biomass-derived components. By having these characteristics, the method for manufacturing a molded article according to the present disclosure can suitably produce a molded article that is substantially composed of biomass-derived components and achieves both high mechanical strength and low density. The method for manufacturing a molded article according to the present disclosure will be described in detail below.

[0022] (Step of preparing a lignocellulose-containing solution) In the method for producing a molded article of the present disclosure, a step is performed to prepare a lignocellulose-containing solution obtained by dissolving a plant material containing lignocellulose (hereinafter sometimes simply referred to as "plant material") in an organic acid.

[0023] The plant material containing lignocellulose is not particularly limited and includes, for example, at least one selected from the group consisting of woody biomass such as coniferous trees, broad-leaved trees, and the bark of coniferous or broad-leaved trees; herbaceous biomass such as herbaceous plants; crops; unused parts of crops; foliage; fruit peels; cotton; and hemp.

[0024] The woody biomass may be coniferous trees (such as Japanese cedar, cypress, and Japanese red pine) or broad-leaved trees (such as eucalyptus, beech, oak, olive, and citrus fruits). Two or more types may be used in combination. From the viewpoint of effectively utilizing declining forest resources, woody biomass that was previously discarded can be suitably used. For example, wood powder generated during lumbering, or small pieces (chips) that cannot be used as scraps, may be used as plant materials. From the viewpoint of giving molded products a high-quality appearance, so-called high-grade woods such as Japanese cedar and Japanese cypress are preferred. According to this disclosure, wood powder, chips, etc. generated during the lumbering of high-grade wood can be effectively utilized as plant materials.

[0025] The lignocellulosic biomass may be natural wood or a sawn product cut from natural wood. There is no particular limitation on the shape of the lignocellulosic biomass, and for example, it can be appropriately selected and used in the form of a plate, chip, powder, etc.

[0026] Examples of the herbaceous biomass include sugarcane bagasse, rice straw, wheat, bran, tomato, onion, bamboo, weeds, etc. Two or more of them may be used in combination.

[0027] Lignocellulose forms a higher-order structure in which cellulose, hemicellulose, and lignin are intricately intertwined. Specifically, cellulose, which is a linear polymer, forms a crystal structure through intramolecular and intermolecular hydrogen bonds to constitute strong microfibrils (cellulose microfibrils), and hemicelluloses such as xylan and glucomannan are intertwined with this, and furthermore, lignin, which is an irregular aromatic polymer, is filled in the voids of the matrix of these polysaccharides.

[0028] In the plant material containing lignocellulose, the total content of cellulose, hemicellulose, and lignin (or the content as lignocellulose) is not particularly limited. From the viewpoint of imparting an appearance similar to natural wood, the total content of cellulose, hemicellulose, and lignin may be 90% by weight or more, 95% by weight or more, 98% by weight or more, or 100% by weight. Some or all of the hydroxyl groups of this cellulose, hemicellulose, and lignin may be formylated.

[0029] In the molded body of the present disclosure, when preparing a lignocellulose-containing solution in which the plant material containing lignocellulose is dissolved in an organic acid, a pulverized product of the plant material containing lignocellulose can be used. That is, before mixing the plant material containing lignocellulose and the organic acid, the plant material containing lignocellulose can be pulverized and adjusted to a desired size. The size of the pulverized product is not particularly limited as long as the molded product of the present disclosure can be obtained, and the maximum diameter in a plan view may be 50 mm or less, 40 mm or less, or 30 mm or less. From the viewpoint of preventing dust, the size of the plant material is preferably 0.1 mm or more in the maximum diameter in a plan view.

[0030] In the manufacturing method of this disclosure, a pulverized plant material containing lignocellulose is also used in the step of obtaining a mixture of pulverized materials, as described later. As the pulverized material, pulverized material of the aforementioned size can be used.

[0031] The type of organic acid is not particularly limited, but a typical organic acid is a carboxylic acid. It may be an aliphatic carboxylic acid or an aromatic carboxylic acid. From the viewpoint of excellent solubility of plant materials, α-keto acids and carboxylic acids having a formyl group are preferred, and organic acids selected from the group consisting of formic acid, glyoxylic acid, and pyruvic acid are particularly preferred. Formic acid, which can be produced using wood gas (a mixed gas of carbon dioxide and hydrogen) as a raw material, is particularly preferred. In the method for producing molded articles of this disclosure, when formic acid is used as the organic acid, in the resulting molded article, a formyl group is bonded to the solid content of the lignocellulose-containing solution in which the plant material containing lignocellulose is dissolved in the organic acid.

[0032] Here, "dissolution" refers to a state in which the shape of the plant material immersed in the organic acid cannot be visually recognized. Even if fibrous material derived from lignocellulose in the plant material can be observed by microscopic observation, if the shape of the plant material itself has disappeared, it is defined as "dissolution." In this disclosure, a liquid in such a "dissolved" state is defined as a "solution," and a solution in which lignocellulose-containing plant material is dissolved in an organic acid is referred to as a "lignocellulose-containing solution." It is preferable that the lignocellulose-containing plant material dissolves uniformly in the organic acid, but the plant material may be partially dissolved in the organic acid. In the case of partial dissolution, a lignocellulose-containing solution may be obtained by removing the undissolved portion by filtration or the like.

[0033] The amount of organic acid to be mixed with the lignocellulose-containing plant material is appropriately selected depending on the type and shape of the plant material, the type of organic acid, etc. From the viewpoint of improving dissolution efficiency, the amount of organic acid may be 4 parts by weight or more, or 9 parts by weight or more, per 1 part by weight of the lignocellulose-containing plant material. From the viewpoint of improving manufacturing efficiency, the amount of organic acid may be 200 parts by weight or less, 100 parts by weight or less, or 50 parts by weight or less, per 1 part by weight of the lignocellulose-containing plant material. As long as the effects of this disclosure are obtained, the organic acid may be added to the lignocellulose-containing plant material as is, or it may be added to the lignocellulose-containing plant material as a solution of a desired concentration.

[0034] As long as a lignocellulose-containing solution can be obtained, the dissolution conditions are not particularly limited and can be appropriately selected depending on the type and shape of the plant material containing lignocellulose, the type of organic acid, etc. For example, from the viewpoint of high dissolution efficiency, the dissolution temperature may be 20°C or higher, 30°C or higher, or 40°C or higher. From the viewpoint of energy reduction, the dissolution temperature may be 100°C or lower, 90°C or lower, or 80°C or lower. The dissolution time can be appropriately set according to the dissolution temperature.

[0035] From the viewpoint of promoting dissolution, after adding the plant material containing lignocellulose to the organic acid, stirring may be performed, or stirring may be performed with grinding. By performing stirring with grinding in the organic acid, dissolution of the plant material becomes possible under milder conditions. Examples of equipment for stirring with grinding include bead mills, colloid mills, disc refiners, and conical refiners.

[0036] From the viewpoint of promoting dissolution, pressurization or depressurization may be performed using pressure adjustment means before mixing the plant material with the organic acid, and / or after mixing the plant material containing lignocellulose with the organic acid. It is believed that the pressure fluctuations applied to the plant material by the pressure adjustment means relax the strong higher-order structure of cellulose, especially lignocellulose, in the plant material, thereby improving its solubility in the organic acid. Pressurization or depressurization allows for dissolution at relatively low temperatures, reducing the energy required for heating and / or maintaining temperature during dissolution. From the viewpoint that the organic acid is efficiently introduced into the tissue of the plant material by the pressure fluctuations, it is preferable to pressurize or depressurize after adding the organic acid to the plant material.

[0037] When reducing pressure, it is preferable to reduce the pressure in the range of 1.0 kPa to 10.0 kPa (absolute pressure). When increasing pressure, it is preferable to increase the pressure in the range of 200 kPa to 1000 kPa (gauge pressure). In this specification, absolute pressure is used when the pressure obtained by the reduced pressure treatment is lower than atmospheric pressure, and gauge pressure based on atmospheric pressure is used when the pressure obtained by the increased pressure treatment is higher than atmospheric pressure.

[0038] The pressure adjustment means used for pressurized or depressurized processing are not particularly limited. The pressure may be adjusted to the aforementioned pressure range using known means such as aspirators, ejectors, compressors, or mechanical pumps.

[0039] The solid content concentration of the plant solution obtained by dissolving plant material in an organic acid is not particularly limited, but from the viewpoint of ease of removal of liquid components, the solid content concentration of the plant solution may be 0.5 (w / v)% or more, 1.0 (w / v)% or more, 1.5 (w / v)% or more, or 2.0 (w / v)% or more. From the viewpoint of ease of manufacture, the solid content concentration of the plant solution may be 20 (w / v)% or less, 15 (w / v)% or less, or 10 (w / v)% or less. The plant solution may further contain known additives such as pigments, to the extent that the effects of this disclosure are not hindered.

[0040] (Step to obtain a mixture of pulverized materials) In the method for manufacturing a molded article according to the present disclosure, after the step of preparing a lignocellulose-containing solution, the pulverized material of a plant material containing lignocellulose is mixed with the lignocellulose-containing solution to obtain a mixture of pulverized materials. The size of the pulverized materials is as described above.

[0041] In the process described above, the mass ratio of the pulverized plant material containing lignocellulose to the solid content of the lignocellulose-containing solution is set to a range of 0.5:9.5 to 9.5:0.5. From the viewpoint of more favorably exhibiting the effects of the present invention, the mass ratio is preferably in the range of 1.0:9.0 to 9.0:1.0, more preferably in the range of 1.2:8.8 to 8.8:1.2, even more preferably in the range of 1.5:8.5 to 8.5:1.5, and particularly preferably in the range of 5.0:5.0 to 8.0:2.0.

[0042] Furthermore, in this disclosure, the solid content of the mixture is substantially composed of biomass-derived components. Specifically, the solid content of the mixture being substantially composed of biomass-derived components means that the content of biomass-derived components in the solid content is, for example, 80% by mass or more, preferably 90% by mass or more, more preferably 95% by mass or more, and even more preferably 98% by mass or more, and it is also preferable that the content is 100% by mass.

[0043] Regarding the method for mixing pulverized plant material containing lignocellulose with a lignocellulose-containing solution, any means of mixing the pulverized material and the solution is acceptable, such as using a stirrer. The mixing temperature can be, for example, around 10 to 40°C, and the mixing can be carried out, for example, under atmospheric pressure.

[0044] (Molding process to obtain a molded article) In the method for manufacturing a molded article according to the present disclosure, after the step of obtaining a mixture of pulverized materials, the solid portion of the mixture is molded to obtain a molded article (molding process).

[0045] In the molding process, the liquid component is removed from the mixture, and the solid component is recovered. By molding this solid component into a desired shape (e.g., a sheet), a molded article of the present disclosure, substantially formed from biomass-derived components, is obtained.

[0046] The method for obtaining a molded article by removing liquid components from a mixture of pulverized materials is not particularly limited. For example, the molded article of the disclosure may be obtained by casting the mixture into a container of a desired size and shape and drying it to remove the liquid components, or by molding the dried solids into a desired shape. Furthermore, from the viewpoint of improving drying efficiency, the plant solution may be concentrated before drying using known concentration methods such as evaporation concentration or vacuum concentration. Water or alkali may be added to the mixture as a precipitating agent, as long as the effects of the disclosure are obtained. The molded article of the disclosure may be obtained by forming the precipitated solids into a sheet and drying it. Since some of the components contained in the plant material may be lost in methods using precipitating agents, the casting method is preferred.

[0047] In the molded body obtained in this way, the organic acid added during dissolution is removed as a liquid component. This molded body is a mixture of pulverized lignocellulose-containing plant material and dissolved lignocellulose-containing plant material, which has been regenerated as a solid component, and is substantially composed solely of biomass-derived components (particularly plant-derived components).

[0048] The plant-derived components mainly consist of cellulose. The plant-derived components may also include lignin and hemicellulose along with cellulose. Preferably, the plant-derived components include one or more selected from the group consisting of cellulose, hemicellulose, and lignin. Some or all of the hydroxyl groups of cellulose, hemicellulose, and lignin may be formylated. The plant-derived components may further include tannins, catechins, polyphenols such as flavonoids, terpenes, etc.

[0049] Furthermore, the solid component obtained by removing the liquid component from the mixture of pulverized materials may be washed to further remove organic acid-derived components, alkali-derived components, etc. Distilled water can be used for washing.

[0050] The shape, size, etc., of the molded article of this disclosure are not particularly limited. Regarding the shape of the molded article, a sheet shape is preferred, for example. If the molded article is a sheet material, the thickness of the sheet material is not particularly limited and can be adjusted, for example, by the solid content concentration of the mixture. The average thickness of the sheet material may be, for example, 10 μm or more, 100 μm or more, or 200 μm or more. Furthermore, the average thickness of the sheet material may be, for example, 5000 μm or less, 1000 μm or less, 800 μm or less, or 600 μm or less. The "average thickness" described herein is the average value of measurements taken multiple times using known means. Also, "sheet material" refers to a thin, flat member, and is a concept that includes so-called sheets and films.

[0051] In the method for manufacturing a molded article according to the present disclosure, the molding step preferably includes a step of hot-pressing the solid components of the mixture in a mold. The conditions for hot-pressing are not particularly limited, but the pressure of the hot-pressing is preferably 1 MPa or more, more preferably 5 MPa or more, even more preferably 20 MPa or more, and also preferably 50 MPa or less, more preferably 40 MPa or less, even more preferably 30 MPa or less, with a preferred range being approximately 1 to 50 MPa.

[0052] Furthermore, the temperature of the hot press is preferably 80°C or higher, more preferably 100°C or higher, even more preferably 110°C or higher, and also preferably 300°C or lower, more preferably 250°C or lower, even more preferably 230°C or lower, with a preferred range being around 80 to 300°C.

[0053] Furthermore, the hot pressing time is preferably 5 minutes or more, more preferably 10 minutes or more, even more preferably 15 minutes or more, and also preferably 60 minutes or less, more preferably 45 minutes or less, even more preferably 30 minutes or less, with a preferred range being around 5 to 60 minutes.

[0054] In the molded article (100% by mass) obtained by the manufacturing method of the present disclosure, the total ratio of the solid content of the pulverized plant material containing lignocellulose and the lignocellulose-containing solution is preferably 50% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, even more preferably 98% by mass or more, and may be 100% by mass.

[0055] Furthermore, the molded articles of this disclosure may be used alone or laminated with other components. The molded articles of this disclosure can be suitably used, for example, as wood-based boards. As wood-based boards, there may be fiberboards (fiber boards) made by molding wood after it has been crushed into fibrous material, or particleboards made by molding wood after it has been crushed into chip-like material. Examples of fiberboards include hardboards, insulation boards, and MDF (medium-density fiberboard). Particleboards and fiberboards can be obtained by mixing small pieces or fibers (crushed material) of various types of wood with a plant solution containing lignocellulose to form a mixture, and then compressing it under high humidity and high pressure. These are wood-based boards made from 100% plant materials and do not contain chemicals such as organic solvents.

[0056] While this disclosure provides a molded article made entirely from plant materials, the molded article may contain plant-derived components and components other than plant materials, as long as they do not impair the effects of this disclosure. For example, when imparting a desired function to the molded article, the article may contain known additives. Examples of such additives include conductive agents, magnetic powders, antibacterial agents, flame retardants, antioxidants, and ultraviolet absorbers.

[0057] By adding a conductive agent to the molded body, a molded body can be obtained that suppresses the accumulation of static electricity and reduces electrostatic discharge during the drying period. Furthermore, by adding magnetic powder to the molded body, laminates that can be attracted and fixed by magnets, or laminates that can shield electromagnetic waves emitted from the sun, electronic equipment, etc., can be obtained. Molded bodies obtained by adding an antibacterial agent can be used in sanitary and toiletry fields and hygiene material applications where antibacterial and antiviral properties are required. In addition, the addition of an antibacterial agent has the effect of suppressing the biodegradation of the molded body itself and changes in appearance due to bacterial growth. Molded bodies obtained by adding a flame retardant can be used in the construction field where fire resistance is required. Molded bodies obtained by adding an antioxidant or ultraviolet absorber can be used in the construction field where weather resistance and light resistance are required.

[0058] Particleboard is classified into single-layer, three-layer, and multi-layer types based on its composition. Three-layer particleboard consists of fine particles in both surface layers (front and back layers) and a relatively coarse particle in the inner layer (core layer). Multi-layer particleboard consists of a continuous arrangement of fine particles to coarse particles from the surface to the core layer. The molded articles of this disclosure can be applied to any of these configurations.

[0059] When the molded body of this disclosure is applied to particleboard, in the particleboard manufacturing process, a lignocellulose-containing solution is sprayed as an adhesive using a glue blender onto wood chips obtained by cutting, crushing, and drying wood, etc., as pulverized plant material containing lignocellulose, to obtain a mixture. In this case, in the method for manufacturing the molded body of this disclosure, the mass ratio of the pulverized plant material containing lignocellulose to the solid content of the lignocellulose-containing solution is set to a specific range of 0.5:9.5 to 9.5:0.5. Furthermore, particleboard is manufactured by removing the liquid from the mixture and molding it. In the method for manufacturing the molded body of this disclosure, the lignocellulose-containing solution functions as an adhesive instead of conventional adhesives, resulting in a 100% plant-based particleboard that does not generate formaldehyde or other harmful substances.

[0060] [Molded Article] The molded article of the present disclosure comprises pulverized plant material containing lignocellulose and solid components of a lignocellulose-containing solution obtained by dissolving the lignocellulose-containing plant material in an organic acid, wherein the mass ratio of the pulverized material to the solid components is 0.5:9.5 to 9.5:0.5, and is characterized by being substantially composed of biomass-derived components. By having these characteristics, the molded article of the present disclosure is substantially composed of biomass-derived components and can achieve both high mechanical strength and low density.

[0061] The method for manufacturing the molded article described herein is not limited to a specific method, but it can be suitably manufactured by the method described in the section above, "Method for Manufacturing a Molded Article."

[0062] Details of the pulverized lignocellulose-containing plant material and the solid content of the lignocellulose-containing solution obtained by dissolving the lignocellulose-containing plant material in an organic acid, which constitute the molded article of this disclosure, are as described in the section [Method for Manufacturing the Molded Article] above.

[0063] As described above, in the molded article of this disclosure, the mass ratio of the pulverized plant material containing lignocellulose to the solid content of the lignocellulose-containing solution is set in the range of 0.5:9.5 to 9.5:0.5. From the viewpoint of more favorably exhibiting the effects of the invention of this disclosure, the mass ratio is preferably in the range of 1.0:9.0 to 9.0:1.0, more preferably in the range of 1.2:8.8 to 8.8:1.2, even more preferably in the range of 1.5:8.5 to 8.5:1.5, and particularly preferably in the range of 5.0:5.0 to 8.0:2.0.

[0064] As described above, in the molded article (100% by mass) of the present disclosure, the total ratio of the solid content of the pulverized plant material containing lignocellulose and the lignocellulose-containing solution is preferably 50% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, even more preferably 98% by mass or more, and may be 100% by mass.

[0065] Furthermore, as stated above, the shape, size, etc., of the molded article of this disclosure are not particularly limited. Moreover, as stated above, the molded article of this disclosure may be used alone or laminated with other components (for example, biomass material, plastic, metal, ceramic, glass, pulp mold, paper, etc.). The molded article of this disclosure can be suitably used, for example, as a wood-based board (such as the aforementioned fiberboard or particleboard).

[0066] The type of plastic used for other components is not particularly limited. Examples include polyethylene, polypropylene, ABS (acrylonitrile-butadiene-styrene copolymer), polystyrene, polymethyl methacrylate, polylactic acid, PEEK (polyetheretherketone resin), polycarbonate, polyurethane, polyester, PET (polyethylene phthalate), LCP (liquid crystal polymer), etc. The plastic may also be in foam form.

[0067] Other materials include, for example, metals such as iron, stainless steel, nickel, copper, silver, gold, aluminum, and tinplate. Ceramics include pottery and other fired materials.

[0068] Furthermore, regarding other components, the paper may be kraft paper, hardwood pulp (LBKP), or softwood pulp (NBKP). Softwood pulp (NBKP) is suitable because it is strong and tear-resistant even when thin, and has high strength, making it suitable for a wide range of applications. Depending on the relationship between the desired strength and cost, it may be hardwood pulp (LBKP) or a mixture of softwood pulp (NBKP).

[0069] Furthermore, as described above, when formic acid is used as the organic acid, the solid content of the lignocellulose-containing solution in the molded article of this disclosure contains formyl groups. That is, in the solid content, formyl groups are bonded to the lignocellulose. In the molded article of this disclosure, the formylated and non-formylated regions can be quantified by the following method.

[0070] (Quantitative analysis of formylated and non-formylated regions) A cross-section of the molded body is photographed in color using a digital microscope. The color data is converted to an 8-bit grayscale image using image processing software (ImageJ). Then, the image is extracted with a brightness value of 0 to 75 and binarized into black and white to determine the area ratio of the white region to the black region. The white region indicates the formylated region.

[0071] In the molded article of this disclosure, the ratio of the non-formylated region to the formylated region (non-formylated region: formylated region), measured by the above method using a digital microscope, is more preferably 8.5:1.5 to 1.5:8.5, more preferably 8.2:1.8 to 5.0:5.0, and even more preferably 8.0:2.0 to 5.5:4.5.

[0072] Furthermore, in the molded article of this disclosure, the formylated region and the non-formylated region can also be measured by the following two methods.

[0073] Method 1. Micro-IR method. Micro-IR is measured on the cross-section of the molded body. The measurement is performed by dividing a 1 cm x 1 cm area into 10 x 10 rows, for a total of 100 regions. The IR spectrum of each region is measured at 600 cm². -1 From 4000cm -1 The measurement is performed up to 1060 cm², which corresponds to the ether bond of cellulose. The measurement method is the ABS method. -1 Let P1 be the peak height, corresponding to the formyl group, and 1715 cm. -1Let the peak height be P2. Let the peak intensity of the formyl group be P2 / P1. Peak intensity of formyl group (M) = P2 / P1 In advance, perform the same measurement on the wood powder (the blended one), and obtain the value of P2 / P1 (=P3). When the value of P3 is less than 0.01, set P3 = 0.01. In the actual sample, when the value of P2 / P1 exceeds twice the value of P3, it is determined that the region is formylated. Region that is formylated: M > 2xP3 Region that is not formylated: M < 2xP3 Furthermore, for the sample obtained by molding wood powder (Sample 1), the sample obtained by molding only dissolved wood (Sample 2), and the samples obtained by molding a blend of wood powder and dissolved wood in a ratio of X1:X2 (Samples 3 to 5), perform the above measurement, and create the relationship (calibration curve) between the blending ratio and the measured ratio. In the measurement of the actual sample, the blending ratio can be measured by converting the measured ratio to the blending ratio using the calibration curve.

[0074] Method 2. Method using microscopic Raman. It is the same as the microscopic IR method of Method 1 above, except that Raman is used instead of IR.

[0075] The molded body of the present disclosure preferably has a density measured by the following measurement method of 1200 kg / m 3 Hereinafter, more preferably 1150 kg / m 3 Hereinafter, even more preferably 1050 kg / m 3 Hereinafter, and preferably 700 kg / m 3 Hereinafter, more preferably 750 kg / m 3 Hereinafter, even more preferably 800 kg / m 3 Hereinafter, and the preferable range is 700 to 1200 kg / m 3 、700 to 1150 kg / m 3 、700 to 1050 kg / m 3 、750 to 1200 kg / m 3 、750 to 1150 kg / m 3 、750 to 1050 kg / m 3 、800 to 1200 kg / m 3 、800 to 1150 kg / m 3 、800 to 1050 kg / m3 These are some examples.

[0076] (Density) In accordance with JIS A 5905 "Fiberboard" 7.4 Density Test, the apparent density of the molded body (g / cm³) 3 Measure the following. Use the average of each of the five measurements.

[0077] Furthermore, the molded article of this disclosure has a bending strength of preferably 2 N / mm², as measured by the following measurement method. 2 More specifically, 5 N / mm 2 More preferably 8 N / mm 2 The above is true, and preferably 120 N / mm 2 More preferably, 100 N / mm 2 More preferably, 80 N / mm 2 The following is a preferred range: 2 to 120 N / mm 2 These are some examples.

[0078] (Method for measuring bending strength) Bending strength is measured using a small universal testing machine. A three-point bending test fixture is used, with a support distance (span) of 60 mm. A load is applied to the surface of a test specimen that is 80 mm long and 10 mm wide at an average deformation rate of 2 mm / min, and the bending strength is measured.

[0079] The present disclosure will be described in detail below with reference to examples and comparative examples. However, the present disclosure is not limited to the examples.

[0080] (Manufacturing of molded bodies) [Example 1] 20 g of oak wood powder (a pulverized plant material containing lignocellulose), which is a plant material containing lignocellulose, was placed in a 1000 ml vial. 980 g of formic acid (manufactured by Nacalai Tesque) with a concentration of 70% by weight was added to this vial. The temperature was then raised to 55°C and stirring was started. After continuing stirring for 7 days under atmospheric pressure, it was confirmed by visual inspection that the oak wood powder had disappeared, and a uniform lignocellulose-containing solution was obtained.

[0081] Next, oak wood powder (a pulverized plant material containing lignocellulose) and the lignocellulose-containing solution obtained from the oak wood powder were mixed in a mass ratio (solid content ratio) of 4:1 (Table 1) to obtain an oak wood powder mixture. The liquid component of the obtained oak wood powder mixture was removed under conditions of 10-50 kPaA and 50°C to obtain the solid content of the oak wood powder mixture. The obtained solid content was subjected to hot-pressure at a temperature of 110°C, a pressure of 8 MPa, and for 15 minutes to obtain the molded body of Example 1. Fourier transform infrared spectroscopy (FTIR analysis) of this molded body was performed, and the infrared absorption spectrum was found to be in the range of 1715-1725 cm⁻¹. -1 We confirmed that the region exhibits an infrared absorption peak originating from the formyl group.

[0082] [Examples 2 and 3] Molded bodies of Examples 2 and 3 were obtained in the same manner as in Example 1, except that a mixture of oak wood powder (a pulverized plant material containing lignocellulose) and the lignocellulose-containing solution obtained from the oak wood powder was mixed in the mass ratio (solid content ratio) shown in Table 1 to obtain a mixture of oak wood powder. Fourier transform infrared spectroscopy (FTIR analysis) was performed on these molded bodies, and the infrared absorption spectrum was found to be between 1715 and 1725 cm⁻¹. -1 We confirmed that the region exhibits an infrared absorption peak originating from the formyl group.

[0083] [Comparative Example 1] Without using a lignocellulose-containing solution, a molded body of Comparative Example 1 was obtained by hot-pressing only oak wood powder (a pulverized plant material containing lignocellulose) at a temperature of 110°C, a pressure of 8 MPa, and for 15 minutes. Fourier transform infrared spectroscopy (FTIR analysis) of this molded body revealed an infrared absorption spectrum of 1715-1725 cm⁻¹. -1 We confirmed that no infrared absorption peak originating from the formyl group was observed in this region.

[0084] [Comparative Example 2] A homogeneous lignocellulose-containing solution was obtained in the same manner as in Example 1. Next, without using oak wood powder (a pulverized plant material containing lignocellulose), the liquid component of the lignocellulose-containing solution was removed under conditions of 10-50 kPaA and 50°C to obtain the solid component of the oak wood powder mixture. The obtained solid component was subjected to hot-pressure at a temperature of 110°C and a pressure of 8 MPa for 15 minutes to obtain the molded body (sheet material) of Comparative Example 2. Fourier transform infrared spectroscopy (FTIR analysis) of this molded body was performed, and the infrared absorption spectrum was found to be in the range of 1715-1725 cm⁻¹. -1 We confirmed that the region exhibits an infrared absorption peak originating from the formyl group.

[0085] [Example 4] 20 g of onion peel (a pulverized plant material containing lignocellulose), which is a plant material containing lignocellulose, was placed in a 1000 ml vial. 980 g of 70% by weight formic acid (manufactured by Nacalai Tesque) was added to this vial. The temperature was then raised to 55°C and stirring was started. After stirring continued for 7 days under atmospheric pressure, it was confirmed by visual inspection that the onion peel had disappeared, and a homogeneous lignocellulose-containing solution was obtained.

[0086] Next, oak wood flour (a pulverized plant material containing lignocellulose) and the lignocellulose-containing solution obtained from onion peels were mixed in a mass ratio (solid content ratio) of 4:1 (Table 2) to obtain a mixture of oak wood flour and onion peels. The liquid component of the obtained mixture of oak wood flour and onion peels was removed under conditions of 10-50 kPaA and 50°C to obtain the solid content of the mixture. The obtained solid content was subjected to hot-pressure at a temperature of 110°C, a pressure of 8 MPa, and for 15 minutes to obtain the molded body of Example 4. Fourier transform infrared spectroscopy (FTIR analysis) of this molded body was performed, and the infrared absorption spectrum was found to be in the range of 1715-1725 cm⁻¹. -1 We confirmed that the region exhibits an infrared absorption peak originating from the formyl group.

[0087] [Example 5] 20 g of weed (a pulverized plant material containing lignocellulose), which is a plant material containing lignocellulose, was placed in a 1000 ml vial. 980 g of 70% by weight formic acid (manufactured by Nacalai Tesque) was added to this vial. The temperature was then raised to 55°C and stirring was started. After stirring continued for two days under atmospheric pressure, the disappearance of the weed was confirmed by visual inspection, and a homogeneous lignocellulose-containing solution was obtained.

[0088] Next, oak wood powder (a pulverized plant material containing lignocellulose) and the lignocellulose-containing solution obtained from weeds were mixed in a mass ratio (solid content ratio) of 4:1 (Table 2) to obtain a mixture of oak wood powder and weeds. The solid content of the mixture was obtained by removing the liquid component from the obtained mixture of oak wood powder and weeds under conditions of 10-50 kPaA and 50°C. The obtained solid content was subjected to hot-pressure at a temperature of 110°C, a pressure of 8 MPa, and 15 minutes to obtain the molded body of Example 5. Fourier transform infrared spectroscopy (FTIR analysis) of this molded body was performed, and the infrared absorption spectrum was found to be in the range of 1715-1725 cm⁻¹. -1 We confirmed that the region exhibits an infrared absorption peak originating from the formyl group.

[0089] [Example 6] 20 g of mandarin orange peel (a pulverized plant material containing lignocellulose), which is a plant material containing lignocellulose, was placed in a 1000 ml vial. 980 g of 70% by weight formic acid (manufactured by Nacalai Tesque) was added to this vial. The temperature was then raised to 55°C and stirring was started. After stirring continued for two days under atmospheric pressure, it was confirmed by visual inspection that the mandarin orange peel had disappeared, and a homogeneous lignocellulose-containing solution was obtained.

[0090] Next, oak wood powder (a pulverized plant material containing lignocellulose) and the lignocellulose-containing solution obtained from mandarin orange peel were mixed in a mass ratio (solid content ratio) of 4:1 (Table 2) to obtain a mixture of oak wood powder and mandarin orange peel. The solid content of the mixture was obtained by removing the liquid component from the obtained mixture of oak wood powder and mandarin orange peel under conditions of 10-50 kPaA and 50°C. The obtained solid content was subjected to hot-pressure at a temperature of 110°C, a pressure of 8 MPa, and 15 minutes to obtain the molded body of Example 6. Fourier transform infrared spectroscopy (FTIR analysis) of this molded body was performed, and the infrared absorption spectrum was found to be in the range of 1715-1725 cm⁻¹. -1 We confirmed that the region exhibits an infrared absorption peak originating from the formyl group.

[0091] [Example 7] 20 g of olive leaves (a pulverized plant material containing lignocellulose), which is a plant material containing lignocellulose, was placed in a 1000 ml vial. 980 g of 70% by weight formic acid (manufactured by Nacalai Tesque) was added to this vial. The temperature was then raised to 55°C and stirring was started. After stirring continued for 7 days under atmospheric pressure, the disappearance of the olive leaves was confirmed by visual inspection, and a homogeneous lignocellulose-containing solution was obtained.

[0092] Next, oak wood powder (a pulverized plant material containing lignocellulose) and the lignocellulose-containing solution obtained from olive leaves were mixed in a mass ratio (solid content ratio) of 2:1 (Table 2) to obtain a mixture of oak wood powder and olive leaves. The liquid component of the obtained mixture of oak wood powder and olive leaves was removed under conditions of 10-50 kPaA and 50°C to obtain the solid content of the mixture. The obtained solid content was subjected to hot-pressure at a temperature of 110°C and a pressure of 8 MPa for 15 minutes to obtain the molded body of Example 7. Fourier transform infrared spectroscopy (FTIR analysis) of this molded body was performed, and the infrared absorption spectrum was found to be in the range of 1715-1725 cm⁻¹. -1 We confirmed that the region exhibits an infrared absorption peak originating from the formyl group.

[0093] [Example 8] The molded body of Example 8 was obtained in the same manner as in Example 1, except that the hot and pressure conditions for the solid portion of the oak wood powder mixture were changed from "temperature 110°C, pressure 8 MPa, 15 minutes" to "temperature 150°C, pressure 8 MPa, 15 minutes" (Table 3).

[0094] [Example 9] The molded body of Example 9 was obtained in the same manner as in Example 1, except that the hot and pressure conditions for the solid portion of the oak wood powder mixture were changed from "temperature 110°C, pressure 8 MPa, 15 minutes" to "temperature 175°C, pressure 8 MPa, 15 minutes" (Table 3).

[0095] [Example 10] The molded body of Example 10 was obtained in the same manner as in Example 1, except that the hot and pressure conditions for the solid portion of the oak wood powder mixture were changed from "temperature 110°C, pressure 8 MPa, 15 minutes" to "temperature 200°C, pressure 8 MPa, 15 minutes" (Table 3).

[0096] [Example 11] The molded body of Example 11 was obtained in the same manner as in Example 1, except that the hot and pressure conditions for the solid portion of the oak wood powder mixture were changed from "temperature 110°C, pressure 8 MPa, 15 minutes" to "temperature 225°C, pressure 8 MPa, 15 minutes" (Table 3).

[0097] [Example 12] The molded body of Example 12 was obtained in the same manner as in Example 1, except that the hot and pressure conditions for the solid portion of the oak wood powder mixture were changed from "temperature 110°C, pressure 8 MPa, 15 minutes" to "temperature 150°C, pressure 8 MPa, 30 minutes" (Table 3).

[0098] [Example 13] The molded body of Example 13 was obtained in the same manner as in Example 1, except that the hot and pressure conditions for the solid portion of the oak wood powder mixture were changed from "temperature 110°C, pressure 2 MPa, 15 minutes" to "temperature 150°C, pressure 8 MPa, 60 minutes" (Table 3).

[0099] [Evaluation of physical properties of molded articles] (Density) In accordance with JIS A 5905 "Fiberboard" 7.4 Density Test, the apparent density (g / cm³) of the molded article is determined. 3 The following measurements were taken. The average of each of the five measurements is shown in Table 1-3 below.

[0100] (Bending strength) Under the following measurement conditions, the bending strength (N / mm²) of the molded body was measured. 2 The bending strength was measured using a small, universal testing machine, the EZ Test, manufactured by Shimadzu Corporation. A three-point bending test fixture was used, with a support distance (span) of 60 mm. A load was applied to the surface of a test specimen measuring 80 mm in length and 10 mm in width at an average deformation rate of 2 mm / min, and the bending strength was measured. The results are shown in Table 1-3 below.

[0101] (Formylation Rate) The formylation rate of the molded article was measured under the following measurement conditions. The results are shown in Figure 1.

[0102] The cross-section of the molded body is photographed in color using a digital microscope. The color data is then converted to an 8-bit grayscale image using image processing software (ImageJ). The image is then extracted at a brightness value of 0 to 75 and binarized into black and white to determine the area ratio of the white region to the black region. The white region represents the formylated region.

[0103]

[0104]

[0105]

[0106] [Disclosure Items] Each of the following items discloses a preferred embodiment. Item 1. A method for producing a molded article, comprising: a step of preparing a lignocellulose-containing solution obtained by dissolving a plant material containing lignocellulose in an organic acid; a step of mixing pulverized lignocellulose-containing plant material with the lignocellulose-containing solution to obtain a mixture of the pulverized material; and a molding step of molding the solid content of the mixture to obtain a molded article, wherein the mass ratio of the pulverized material to the solid content of the lignocellulose-containing solution is 0.5:9.5 to 9.5:0.5, and the solid content of the mixture is substantially composed of biomass-derived components. Item 2. The method for producing a molded article according to Item 1, wherein the plant material containing lignocellulose for dissolution in the organic acid and the plant material containing lignocellulose for obtaining the pulverized material are each independently at least one selected from the group consisting of woody biomass, herbaceous biomass, crops, unused parts of crops, foliage, fruit peels, cotton, and hemp. Item 3. The method for manufacturing a molded article according to item 1 or 2, wherein the molding step includes a step of hot-pressing the solids in a mold. Item 4. The method for manufacturing a molded article according to item 3, wherein the pressure of the hot-press is 1 MPa or more and 50 MPa or less. Item 5. The method for manufacturing a molded article according to item 3 or 4, wherein the temperature of the hot-press is 80°C or more and 300°C or less. Item 6. A molded article comprising pulverized plant material containing lignocellulose and solids of a lignocellulose-containing solution in which the lignocellulose-containing plant material is dissolved in an organic acid, wherein the mass ratio of the pulverized material to the solids of the lignocellulose-containing solution is 0.5:9.5 to 9.5:0.5, and which is substantially composed of biomass-derived components. Item 7. The molded article according to claim 6, wherein the plant material containing lignocellulose for dissolving in the organic acid and the plant material containing lignocellulose for obtaining the pulverized product are each independently at least one selected from the group consisting of woody biomass, herbaceous biomass, crops, unused parts of crops, foliage, fruit peels, cotton, and hemp. Claim 8. The molded article according to claim 6 or 7, wherein the solid content contains formyl groups. Claim 9. The density is 1200 kg / m³ 3The molded article described in any one of items 6 to 8 below. Item 10. The bending strength, as measured by the following measurement method, is 2 N / mm 2 The above applies to the molded body described in any one of items 6 to 9. (Method for measuring bending strength) Bending strength shall be measured using a small universal testing machine. A three-point bending test fixture shall be used, with a support distance (span) of 60 mm. A load shall be applied to the surface of a test piece 80 mm in length and 10 mm in width at an average deformation rate of 2 mm / min, and the bending strength shall be measured.

Claims

1. A method for producing a molded body, comprising the steps of: preparing a lignocellulose-containing solution by dissolving a plant material containing lignocellulose in an organic acid; mixing pulverized plant material containing lignocellulose with the lignocellulose-containing solution to obtain a mixture of the pulverized material; and molding the solid portion of the mixture to obtain a molded body, wherein the mass ratio of the pulverized material to the solid portion of the lignocellulose-containing solution is 0.5:9.5 to 9.5:0.5, and the solid portion of the mixture is substantially composed of biomass-derived components.

2. The method for producing a molded article according to claim 1, wherein the plant material containing lignocellulose for dissolving in the organic acid and the plant material containing lignocellulose for obtaining the pulverized product are each independently at least one selected from the group consisting of woody biomass, herbaceous biomass, crops, unused parts of crops, leaves, fruit peels, cotton, and hemp.

3. The method for manufacturing a molded article according to claim 1 or 2, wherein the molding step includes a step of heat-pressing the solid content in a mold.

4. The method for manufacturing a molded article according to claim 3, wherein the pressure of the hot press is 1 MPa or more and 50 MPa or less.

5. The method for manufacturing a molded article according to claim 3, wherein the temperature of the hot press is 80°C or higher and 300°C or lower.

6. A molded body comprising pulverized plant material containing lignocellulose and solids of a lignocellulose-containing solution in which the lignocellulose-containing plant material is dissolved in an organic acid, wherein the mass ratio of the pulverized material to the solids of the lignocellulose-containing solution is 0.5:9.5 to 9.5:0.5, and which is substantially composed of biomass-derived components.

7. The molded article according to claim 6, wherein the lignocellulose-containing plant material for dissolving in the organic acid and the lignocellulose-containing plant material for obtaining the pulverized product are each independently at least one selected from the group consisting of woody biomass, herbaceous biomass, crops, unused parts of crops, foliage, fruit peels, cotton, and hemp.

8. The molded article according to claim 6 or 7, wherein the solid content includes a formyl group.

9. Density is 1200 kg / m³ 3 The molded article according to claim 6 or 7, which is as follows:

10. The bending strength measured by the following measurement method is 2 N / mm 2 The molded article according to claim 6 or 7. (Method for measuring bending strength) The bending strength is measured using a small universal testing machine. A three-point bending test fixture is used, and the distance between supports (span) is 60 mm. A load is applied to the surface of a test piece with a length of 80 mm and a width of 10 mm at an average deformation rate of 2 mm / min, and the bending strength is measured.

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