Bamboo material for processing, bamboo molded products, methods for manufacturing the same, and composites

Abstract

This invention provides a bamboo material for processing that, through molding processes such as bending and compression, suppresses defects such as cracking and splitting, resulting in a bamboo molded product with good bamboo fiber flow and color tone and superior appearance, as well as a method for manufacturing bamboo molded products using the same. [Solution] The bamboo material for processing according to the present invention is characterized in that the ratio of the total amount of monosaccharides derived from hemicellulose, excluding glucose, to the total amount of monosaccharides derived from the constituent sugar components contained herein is 15 to 32% by mass. The bamboo molded product manufacturing method of the present invention comprises a shaping step of subjecting the bamboo material for processing to bending or compression.

Description

Technical Field

[0001] The present invention relates to a processing bamboo material, a method for manufacturing a bamboo molded product, and a composite, which can suppress defects such as cracks and splits and provide a bamboo molded product with excellent appearance.

Background Art

[0002] Conventionally, as a measure to reduce carbon dioxide emissions for suppressing global warming, effective use of biomass resources such as wood, bamboo materials, rice straw, and wheat straw has been considered. For example, in the case of wood and bamboo materials, attempts have been made to manufacture various molded products using wood powder or bamboo powder generated by cutting or pulverizing them as raw material resources. As a method for manufacturing a bamboo molded body using the bamboo powder obtained by pulverization, Patent Document 1 discloses that pulverized bamboo and water are placed in a reaction vessel, the temperature in the vessel is maintained at 150 to 300°C, and hemicellulose contained in the bamboo is removed by hydrolysis, thereby obtaining a composition mainly composed of cellulose and lignin in a first step, and a second step of adding formaldehyde to the composition obtained in the first step and then heating and compressing to obtain a molded product.

[0003] In addition, a method for manufacturing a bamboo molded product using raw material resources other than bamboo powder is also known. For example, Patent Document 2 discloses a method for manufacturing a compressed bamboo material, which comprises plastifying bamboo material with an arc-shaped cross-section split in the fiber direction with hot water at a temperature of 70 to 120°C, and then compression molding it into a flat shape while applying pressure with both ends of the plastified bamboo material restrained, and fixing the shape by heating the obtained flat bamboo material at a temperature of 140 to 200°C. Patent Document 3 discloses a method for manufacturing bamboo material for bamboo products by fumigating bamboo in a smoke atmosphere containing superheated steam, and bamboo products obtained by processing the obtained bamboo material for bamboo products. Furthermore, Patent Document 4 discloses bamboo cutlery consisting of an action part and a gripping part, in which natural bamboo is processed into a 2 mm thick plate material and dried by irradiation with ultrasonic waves and ultraviolet rays to form a bamboo plate, and the action part and gripping part of a spoon, knife, or fork are made from this bamboo plate, and it is stated that the bamboo plate is dried to a moisture content of 6-7% by irradiation with ultrasonic waves and ultraviolet rays. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2015-214035 [Patent Document 2] Japanese Patent Application Publication No. 9-193105 [Patent Document 3] Japanese Patent Publication No. 2002-18815 [Patent Document 4] Utility Model Registration No. 3226388 Gazette [Overview of the project] [Problems that the invention aims to solve]

[0005] For example, when manufacturing a bamboo molded product by bending flat bamboo material, it is common practice to use bamboo material that has been softened beforehand. However, the composition of the bamboo material may change depending on the softening method. According to the present inventors, when bamboo material softened using hot water, as described above, and in which the ratio of the total amount of monosaccharides derived from hemicellulose (excluding glucose) to the total amount of monosaccharides derived from constituent sugar components (hereinafter referred to as "hemicellulose content") is 33.8% by mass, was subjected to bending, cracks and splits were observed. The object of the present invention is to provide a bamboo material for processing, a bamboo molded product, a method for manufacturing the same, and a composite including a bamboo molded product, which, when subjected to bending or compression processing, suppresses defects such as cracking and splitting, has good bamboo fiber flow and color tone, and exhibits excellent appearance. In this specification, the description of "bending or compression processing" also includes cases where both bending and compression processing are performed. [Means for solving the problem]

[0006] The inventors have found that when bamboo culms are dried, cut, and processed into plate-like bodies suitable for molding, and then brought into contact with a basic liquid to adjust the hemicellulose content to a specific range, and then subjected to bending or compression, defects such as cracking and splitting are suppressed, and a bamboo molded product with good bamboo fiber flow and color tone and excellent appearance can be obtained.

[0007] The present invention is as follows: (1) Bamboo material for processing, which is used as a raw material for manufacturing bamboo molded products by being subjected to molding processes, The processed bamboo material is characterized in that the ratio of the total amount of monosaccharides derived from hemicellulose, excluding glucose, to the total amount of monosaccharides derived from the constituent sugar components contained in the above processed bamboo material is 15 to 32% by mass. (2) A method for manufacturing a bamboo molded product, characterized by comprising a shaping step of subjecting the bamboo material for processing described in (1) above to bending or compression. (3) A bamboo molded product characterized by being obtained by the method described in (2) above. (4) The bamboo molded product according to (3) above, which has a coating on at least a part of its surface. (5) A composite material characterized by being formed by integrating the bamboo molded product described in (3) above with another article. [Effects of the Invention]

[0008] In the present invention, when processing bamboo material having a hemicellulose content within a specific range is subjected to bending or compression processing, defects such as cracking and splitting are suppressed, and bamboo molded products with good bamboo fiber flow and color tone and excellent appearance can be efficiently manufactured. As described above, the bamboo molded products of the present invention have excellent appearance and are therefore useful as everyday items such as tableware, cutlery, and trays, or as components for ornaments, decorations, furniture, musical instruments, audio equipment, electrical appliances, vehicle interiors, housing equipment, bathroom and toilet supplies, pet supplies, cosmetic tools, etc. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic cross-sectional view showing an example of bending (the method for manufacturing the bent plate used in Examples 2-1 to 2-3). [Figure 2] This is a schematic cross-sectional view showing that a bent plate was obtained by the manufacturing method shown in Figure 1. [Figure 3] This is a schematic cross-sectional view showing an example of bending and compression processing (a method for manufacturing a bamboo spoon used in Example 3-1). [Figure 4] Figure 3 is a schematic cross-sectional view showing that a bamboo spoon was obtained using the manufacturing method shown. [Figure 5] This is a perspective view of the front side of the bamboo spoon obtained in Example 3-1. [Figure 6] This is a schematic cross-sectional view showing other examples of bending and compression processes (manufacturing method for bamboo spoons used in Example 3-2). [Figure 7] This is a schematic cross-sectional view showing that a bamboo spoon was obtained by the manufacturing method shown in Figure 6. [Figure 8] This is a perspective view of the front side of the bamboo spoon obtained in Example 3-2. [Figure 9] This is a perspective view of the underside of the bamboo spoon obtained in Example 3-2. [Figure 10] This is a schematic cross-sectional view showing an example of compression processing (a method for manufacturing a bamboo coaster obtained in Example 3-3). [Figure 11]It is a schematic cross-sectional view showing that a bamboo-made coaster was obtained by the manufacturing method of FIG. 10. [Figure 12] It is a plan view of one side of the coaster obtained in Example 3-3. [Figure 13] It is a plan view of the other side of the coaster obtained in Example 3-3.

Embodiments for Carrying Out the Invention

[0010] The bamboo material for processing of the present invention is a material obtained by drying bamboo cut from a bamboo forest and preferably subjected to pretreatment using a basic liquid, and is based on the total amount of monosaccharides derived from the constituent sugar components contained therein. It is an article used for manufacturing a bamboo molded product with excellent appearance, in which the ratio (hemicellulose content) of the total amount of monosaccharides derived from hemicellulose excluding glucose is in a specific range. The constituent sugar components are glucose, arabinose, rhamnose, galactose, xylose and mannose, and the hemicellulose content is 15 to 32% by mass, preferably 17 to 31% by mass, more preferably 19 to 30% by mass.

[0011] If a bamboo material that has not been pretreated or that has been pretreated but has a hemicellulose content exceeding 32% by mass is subjected to bending or compression processing, cracks or splits will occur, so it cannot be used as a bamboo material for processing for manufacturing a bamboo molded product with good appearance. If a bamboo material with a content of less than 15% by mass is subjected to bending or compression processing, the shape of the resulting bamboo molded product may be difficult to maintain. However, the bamboo material for processing of the present invention is a "hemicellulose partially desorbed bamboo material" with a hemicellulose content in a specific range of 15 to 32% by mass, so the above-mentioned problems are solved in the resulting bamboo molded product.

[0012] The hemicellulose content in the bamboo material for processing according to the present invention can be measured by contacting the bamboo material for processing with sulfuric acid to hydrolyze the constituent sugar components contained therein, then reducing the obtained sugars and performing derivatization (acetylation, silylation, etc. using acetic anhydride), and subjecting the resulting sugar derivatized product to gas chromatography. Specifically, it is as follows: The bamboo material for processing is preferably pulverized, and the powder sample is brought into contact with a 60-80% by mass aqueous sulfuric acid solution to perform primary hydrolysis. Next, water is added to this mixture to dilute the sulfuric acid concentration to 2-10% by mass and secondary hydrolysis is performed, after which the residue is removed and the processed solution is recovered. Next, this processed solution is neutralized to pH 5, the contained sugars are reduced with sodium borohydride, and then the above-mentioned derivatization is performed. The resulting derivatized product is then subjected to gas chromatography.

[0013] As described above, the bamboo material for processing in the present invention is derived from bamboo harvested from bamboo groves. The type of bamboo is not particularly limited and can include Madake (Phyllostachys bambusoides), Moso bamboo (Phyllostachys edulis), Hachiku (Phyllostachys nipponicus), Medake (Phyllostachys edulis), Kurochiku (Phyllostachys nipponicus), Hoteichiku (Phyllostachys japonica), Shihouchiku (Phyllostachys spp.), Touchiku (Phyllostachys taimensis), etc.

[0014] The bamboo material for processing according to the present invention is preferably obtained by cutting and processing the culm of a bamboo (even if only the interior with the surface layer removed) to obtain a predetermined shape for molding, and then subjecting it to a pretreatment (basic liquid treatment) to obtain a hemicellulose content within the above range. The shape of the bamboo material for processing is not particularly limited and can be plate-shaped, lumpy (polyhedron, cone, sphere, etc.), linear (rod-shaped), etc. In the case of a plate shape, it can be derived from a curved plate obtained by cutting and processing a bamboo culm, or from a substantially flat plate obtained by correcting the shape of this curved plate. When plate-shaped bamboo material for processing is used, a bamboo molded product can be obtained in which the flow of bamboo fibers is well observed throughout. The surface of the bamboo material for processing used when manufacturing a bamboo molded product by bending or compression may be a smooth surface, a rough surface, a surface with patterned convex parts, or a surface with patterned concave parts.

[0015] As described later, for example, when manufacturing a bamboo molded product by compression processing, one (1 sheet) or two (2 or more sheets) of bamboo material for processing can be used. Therefore, the size of the bamboo material for processing in the present invention is not particularly limited, but in particular, from the viewpoint of moldability by compression processing and the shape stability of the resulting bamboo molded product, the maximum value of the thickness in the compression direction (per sheet) when manufacturing the bamboo molded product is preferably 15 mm, more preferably 13 mm, and even more preferably 10 mm.

[0016] The bamboo material for processing in this invention may be either completely dry or hydrated.

[0017] The method for producing the bamboo material for processing according to the present invention preferably involves cutting or reshaping bamboo harvested from a bamboo forest as necessary, drying it, subjecting the resulting pre-treated bamboo to a basic liquid treatment, and then removing the basic liquid and drying it. Through the basic liquid treatment, the bamboo material for processing according to the present invention, having a hemicellulose content within a specific range, can be obtained.

[0018] The moisture content of the bamboo used for pretreatment before treatment with a basic liquid, i.e., the bamboo used for pretreatment after being cut and dried, is preferably 5 to 20% by mass, more preferably 8 to 12% by mass. The drying method and drying conditions for the cut bamboo are not particularly limited.

[0019] The basic liquid used in the basic liquid treatment may contain at least one basic compound selected from inorganic and organic materials, or a basic liquid organic compound, which dissolves in the medium and exhibits basic properties. The pH of the basic liquid is not particularly limited. To obtain the bamboo material for processing according to the present invention, which is suitable for bending or compression, it is preferable to use a basic aqueous solution obtained by dissolving a basic compound in water as the medium. In this case, the medium may, if necessary, contain a water-soluble organic solvent.

[0020] Inorganic materials used in the preparation of basic liquids include metal hydroxides, metal bicarbonates, and metal carbonates. The basic liquid may contain only one or more inorganic materials.

[0021] Examples of metal hydroxides include alkali metal hydroxides such as sodium hydroxide and potassium hydroxide; and alkaline earth metal hydroxides such as magnesium hydroxide and calcium hydroxide. Examples of metal bicarbonates include alkali metal bicarbonates such as sodium bicarbonate and potassium bicarbonate; and alkaline earth metal bicarbonates such as magnesium bicarbonate and calcium bicarbonate. Examples of metal carbonates include alkali metal carbonates such as sodium carbonate and potassium carbonate; and alkaline earth metal carbonates such as magnesium carbonate, calcium carbonate, and barium carbonate.

[0022] When pre-treatment bamboo is treated with a basic liquid, it is preferable to contact the pre-treatment bamboo with the basic liquid under mild conditions as described below. That is, in order to prevent excessive removal of lignin from the pre-treatment bamboo and to remove a portion of the hemicellulose that binds to cellulose by hydrogen bonding, mild conditions can be established by adjusting, for example, the concentration of the basic compound in the basic liquid, the temperature of the basic liquid that comes into contact with the pre-treatment bamboo, and the contact time between the pre-treatment bamboo and the basic liquid. This makes it possible to obtain a bamboo material for processing that can be used to manufacture bamboo molded products with excellent appearance by bending or compressing the pre-treatment bamboo.

[0023] The concentration of the basic compound in the basic liquid is preferably 0.01 to 25% by mass, more preferably 0.05 to 15% by mass, and even more preferably 1 to 7.5% by mass. The temperature of the basic liquid brought into contact with the pre-treatment bamboo is preferably 20°C to 170°C, more preferably 50°C to 160°C, and even more preferably 80°C to 150°C. The contact time between the pretreatment bamboo and the basic liquid is preferably 0.5 to 48 hours.

[0024] The method for treating the bamboo for pretreatment with a basic liquid is not particularly limited. For example, it can be a method of bringing the bamboo for pretreatment into contact with the basic liquid in a container, or a method of continuously applying the basic liquid, such as spraying it onto the bamboo for pretreatment that has been placed (fixed) in a predetermined position.

[0025] When bamboo for pretreatment is treated with a basic liquid, bamboo material for processing that is wet with the basic liquid is obtained. Subsequently, in order to obtain clean bamboo material for processing, washing (basic liquid removal) is performed to remove the basic liquid adhering to the bamboo material for processing.

[0026] As a method for removing basic liquids, washing with neutral liquids, acidic liquids, etc., can be applied. Examples of neutral liquids include water, and examples of acidic liquids include citric acid aqueous solution. Basic liquid removal can consist of a washing step using one type of neutral liquid (preferably water), or a multi-stage washing step using two or more types of neutral liquids. In the case of a multi-stage washing step, it is preferable to use water as the final step. When removing basic liquids, vibration using ultrasound may be utilized. The neutral liquids and acidic liquids used may also be heated.

[0027] When water is used to remove the basic liquid, a hydrated bamboo material for processing can be obtained. Since the bamboo material used for processing in the manufacture of molded bamboo products may contain an appropriate amount of moisture, if the basic liquid is removed using water, it may be dried afterward to achieve a suitable moisture content. Furthermore, in order to produce bamboo material for processing that is relatively dry and easy to handle before the manufacture of molded bamboo products, and in order to improve the moisture content before the manufacture of molded bamboo products, it is preferable to remove the basic liquid and then dry it thoroughly. In any case, drying methods such as heat drying, vacuum drying, and air drying can be applied.

[0028] The present invention provides a method for manufacturing a bamboo molded product (hereinafter referred to as "the present invention's bamboo molded product manufacturing method") which includes a shaping step of subjecting a bamboo material for processing to bending or compression. The present invention's bamboo molded product manufacturing method may, if necessary, further include a shape adjustment step of polishing the bamboo molded product, a film formation step of forming a protective film or the like on the surface of the bamboo molded product, etc., after the shaping step.

[0029] In the shaping process according to the present invention, bending or compression can be performed regardless of the direction in which the fibers are aligned. At this time, not only simple thinning and bending may be performed, but deformation such as twisting may also occur. The bamboo material used for processing in this shaping process may be one (1 sheet) or two (2 or more sheets). Even if compression is performed with multiple bamboo materials for processing combined, an integrated bamboo molded product with excellent appearance and shape stability can be manufactured. In the present invention, when multiple bamboo materials for processing are used, such a bamboo molded product can be obtained without using adhesive.

[0030] The bamboo material used in the shaping process is preferably a hydrated material from the viewpoint of moldability. In this case, the lower limit of the moisture content of the bamboo material is preferably 5% by mass, more preferably 15% by mass, and even more preferably 25% by mass. However, if the bamboo material used in the shaping process is an oven-dried material or otherwise has too low a moisture content, it is preferable to include a moisture adjustment step before the shaping process to adjust the moisture content of the bamboo material to 5% by mass or more. To achieve such a moisture content, water or a mixture of water and an organic solvent can be used. Methods for bringing the bamboo material into contact with water or the above mixture include bringing the bamboo material into contact with water or the above mixture in a container, spraying water or the above mixture onto the bamboo material, and exposing it to an atmosphere containing water vapor.

[0031] When performing compression processing, a mold is preferably used that has a cavity size close to the shape of the bamboo molded product to be manufactured, or a cavity slightly larger than that shape. Figure 3 is a cross-sectional view showing an example of a method for manufacturing a bamboo molded product (bamboo spoon) having the shape of the part indicated by reference numeral 24 in Figure 4, by subjecting a single piece of bamboo material 11 to compression processing using a mold comprising an upper mold 13 and a lower mold 15. In the present invention, even for curved surfaces such as spoons, defects such as cracks and splits are suppressed, and bamboo molded products with good bamboo fiber flow and color tone and excellent appearance can be efficiently manufactured.

[0032] In the case of compression processing, shearing may occur during compression processing depending on the shape of the bamboo molded product to be manufactured and the shape of the bamboo material used for processing. For example, when manufacturing a bamboo molded product with a recess, if a punch is performed in the center of a block of bamboo material for processing, or in the center of multiple stacked sheets of bamboo material for processing, to form a recess that reflects the shape of the punch tip, the side surface of the edge of the punch tip that bites into the bamboo material for processing may undergo sliding shear deformation during punching. In the present invention, even if such shearing occurs, a bamboo molded product with excellent appearance can be manufactured.

[0033] In the case of bending, it is preferable to fix the bamboo material being processed at least at two points, such as the peripheral edge. A die used in compression processing may also be used.

[0034] In the shaping process according to the present invention, the bending or compression of the bamboo material for processing may be performed while heating, as long as the bamboo material for processing does not deteriorate. The heating temperature is preferably 60°C to 160°C, more preferably 90°C to 120°C. When shaping using a mold, it is preferable to form at 90°C or higher.

[0035] The shaping process according to the present invention may be a process in which bending or compression is performed only once, or it may be a process in which these processes are performed in multiple stages, depending on the shape of the bamboo molded product to be manufactured. In the latter case, it is preferable to bring the bamboo material to be processed into contact with water or the above mixture before performing the second and subsequent processes.

[0036] As described above, the bamboo molded product manufacturing method of the present invention may further include a shape adjustment step, a coating formation step, etc., after the shaping step. The bamboo molded product obtained by the present invention can be used alone or as a component of a composite that is integrated with other articles. In such cases, it is preferable to include a shape adjustment step such as polishing or drilling. Furthermore, in the film formation process, paint or the like is applied to at least a portion of the surface of the bamboo molded product and dried, and if necessary, irradiation with radiation (ultraviolet light, etc.) or heating can be performed. When a transparent film is formed, the clear flow of bamboo fibers exhibited in the bamboo molded product before the application of paint or the like can be suitably observed even in the film-coated bamboo molded product.

[0037] As described above, the bamboo molded product of the present invention can be not only a structure having a curved surface or a structure having a coating on at least a part of its surface, but also a structure with clearly defined ridges, a structure with varying plate thickness, and the like.

[0038] The composite of the present invention is formed by integrating a bamboo molded product with excellent appearance with another article. This integration can be achieved by adhesive, joining members, or fitting, and it is preferable that the structure exposes at least a portion of the surface of the bamboo molded product that has a good appearance. The constituent material of the other article is not particularly limited and can be wood, organic materials such as resin, inorganic materials such as metal, or a combination thereof. [Examples]

[0039] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.

[0040] 1. Manufacturing of bamboo lumber for processing. As raw bamboo, Moso bamboo harvested in Fujian Province, People's Republic of China, was naturally dried (for 3 years), then split in half and dried again (60°C, 16 hours). After importing to Japan, it was dried again (60°C ± 5°C, 10 minutes or more) to reduce the moisture content to 7% by mass or less. Then, pre-processing bamboo of a predetermined size was prepared by cutting. Next, this pre-processing bamboo was immersed in a sodium hydroxide solution to obtain several processing bamboo materials with different hemicellulose content (the ratio of the total amount of monosaccharides derived from hemicellulose, excluding glucose). The hemicellulose content was also measured for the pre-processing bamboo before contact with the sodium hydroxide solution. The method for measuring the hemicellulose content is as follows.

[0041] <Method for measuring hemicellulose content> The analyte (bamboo for pretreatment or bamboo material for processing) was dried to an air-dry state. Then, this dried sample was pulverized using an Osaka Chemical Co., Ltd. grinder, "Absolute Mill ABS-W" (product name), and the resulting powder was used as the measurement sample. Subsequently, 6 ml of 72% by mass sulfuric acid was added to 0.3 g of the sample, and hydrolysis was carried out (room temperature, 2.5 hours). Then, 168 ml of pure water was added to this reaction solution, and the mixture was placed in a sterilization autoclave for further hydrolysis (121°C, 1 hour). Next, the hydrolysate was cooled to room temperature, filtered, and the filtrate was collected. The filtrate was then placed in a volumetric flask, and pure water was added to make a total of 500 milliliters (hereinafter referred to as "sugar component-containing solution"). Subsequently, myo-inositol was added to this sugar component-containing solution as an internal standard. The monosaccharides contained in the sugar component-containing solution (glucose, arabinose, rhamnose, galactose, xylose, and mannose) and the internal standard myo-inositol were reduced with sodium borohydride and acetylated with acetic anhydride. The resulting algitol acetate of sugars was subjected to gas chromatography. The obtained chromatogram was analyzed, and the total amount of hemicellulose-derived sugar components (arabinose, rhamnose, galactose, xylose, and mannose) without conversion to anhydrous sugar was divided by the total amount of glucose, arabinose, rhamnose, galactose, xylose, and mannose, also without conversion to anhydrous sugar, and the percentage was calculated, which was defined as the "hemicellulose content." The measurement conditions for gas chromatography are as follows: Analytical instrument: Shimadzu Corporation gas chromatograph "GC-2010" (model name) Column: SPELCO capillary column "SP-2380" (Size: φ0.53mm x 30m) Column temperature: The column temperature is set to 200°C for the first minute from the start of the analysis, then increased to 250°C at a rate of 5°C per minute, and held at this temperature for 6 minutes. Detector: Flame ionization detector

[0042] Example 1-1 (Manufacturing of bamboo material for processing) A pre-treatment bamboo sample measuring 15 mm (length direction of fiber) x 15 mm (direction perpendicular to fiber) x 3 mm (thickness) was placed in a reaction vessel containing a 3.85% by mass NaOH aqueous solution (135°C), immersed for 3 hours, then removed and washed with water. The basic liquid-treated bamboo material was then sandwiched between two wire meshes and dried at 30°C to obtain a processing bamboo material (hereinafter referred to as "processing bamboo material B1") with a hemicellulose content of 20.2% by mass.

[0043] Example 1-2 (Manufacturing of bamboo material for processing) Except for using a 2.0% by mass NaOH aqueous solution (135°C) instead of a 3.85% by mass NaOH aqueous solution (135°C), the same procedure as in Example 1-1 was carried out to obtain a bamboo material for processing (hereinafter referred to as "bamboo material for processing B2") with a hemicellulose content of 26.4% by mass.

[0044] Example 1-3 (Manufacturing of bamboo material for processing) Except for using a 1.0% by mass NaOH aqueous solution (135°C) instead of a 3.85% by mass NaOH aqueous solution (135°C), the same procedure as in Example 1-1 was carried out to obtain a bamboo material for processing (hereinafter referred to as "bamboo material for processing B3") with a hemicellulose content of 29.1% by mass.

[0045] Example 1-4 (Manufacturing of bamboo material for processing) The same procedure as in Example 1-1 was followed, except that a pre-treatment bamboo piece measuring 105 mm (length direction of fiber) x 105 mm (orthogonal direction of fiber) x 12 mm (thickness) was placed in a reaction vessel containing a 3.85% by mass NaOH aqueous solution (140°C) and immersed for 3 hours to obtain a bamboo material for processing with a hemicellulose content of 28.7% by mass. Under the same conditions, a pre-treatment bamboo piece measuring 180 mm (length direction of fiber) x 50 mm (orthogonal direction of fiber) x 10 mm (thickness) was treated with a basic liquid to obtain the bamboo material for processing used in Example 2-1 (hereinafter referred to as "bamboo material for processing B4").

[0046] Examples 1-5 (Manufacturing of bamboo material for processing) The same procedure as in Example 1-1 was followed, except that a pre-treatment bamboo piece measuring 105 mm (length direction of fiber) × 105 mm (orthogonal direction of fiber) × 12 mm (thickness) was placed in a reaction vessel containing a 5.0 mass% NaOH aqueous solution (140°C) and immersed for 3 hours to obtain a processing bamboo material with a hemicellulose content of 27.6 mass%. Under the same conditions, a pre-treatment bamboo piece measuring 150 mm (length direction of fiber) × 15 mm (orthogonal direction of fiber) × 10 mm (thickness) and a pre-treatment bamboo piece measuring 180 mm (length direction of fiber) × 50 mm (orthogonal direction of fiber) × 10 mm (thickness) were treated with a basic liquid to obtain processing bamboo materials to be used in Examples 2-2 and 2-3 (hereinafter referred to as "processing bamboo material B5X" and "processing bamboo material B5Y," respectively).

[0047] Comparative Example 1-1 (Manufacturing of bamboo material for processing) Except for using a 7.5% by mass NaOH aqueous solution (135°C) instead of a 3.85% by mass NaOH aqueous solution (135°C), the same procedure as in Example 1-1 was carried out to obtain a bamboo material for processing with a hemicellulose content of 12.5% ​​by mass (hereinafter referred to as "bamboo material for processing BB1").

[0048] Comparative Example 1-2 (Manufacturing of bamboo material for processing) Except for using hot water instead of 3.85% by mass-aqueous NaOH aqueous solution (135°C), the same procedure as in Example 1-1 was carried out to obtain bamboo material for processing (hereinafter referred to as "bamboo material for processing BB2") with a hemicellulose content of 33.8% by mass.

[0049] 2. Manufacturing and evaluation of bamboo molded products (1) Bamboo material that had not undergone any pretreatment, and bamboo material for processing obtained in Examples 1-1 to 1-3 and Comparative Examples 1-1 to 1-2 were each subjected to bending, and the appearance of the resulting bent plates was visually evaluated.

[0050] Example 2-1 The bamboo material B1 for processing (hemicellulose content: 20.2% by mass) prepared in Example 1-1 was placed in a constant temperature and humidity chamber and left to stand under conditions of 40°C and 90% humidity. After 48 hours, it was removed and its moisture content was reduced to 30%. Next, the bamboo material 11 for processing was bent using a bending die, as shown in Figure 1, which is equipped with an upper die 13 and a lower die 15 and forms a hemispherical cavity with a radius of curvature of 12 mm when the die is clamped, to obtain a bent plate 21. Specifically, the bamboo material 11 for processing was placed in the die set to 90°C, and the upper die 13 was lowered at a speed of 30 mm per second until the clearance became 3 mm and stopped (see Figure 2). One minute later, the temperature of the die was cooled to approximately 30°C. After 5 minutes, the die was removed to obtain the bent plate 21. Visual inspection of the obtained bent plate revealed that there were no cracks or tears on the surface, and the appearance was good.

[0051] Example 2-2 A bent plate was obtained by performing the same procedure as in Example 2-1, except that processing bamboo material B2 (hemicellulose content: 26.4% by mass) prepared in Example 1-2 was used instead of processing bamboo material B1 (hemicellulose content: 20.2% by mass). When the obtained bent plate was visually inspected, there were no cracks or splits on the surface, and the appearance was good.

[0052] Examples 2-3 A bent plate was obtained by performing the same procedure as in Example 2-1, except that processing bamboo material B3 (hemicellulose content: 29.1% by mass) prepared in Example 1-2 was used instead of processing bamboo material B1 (hemicellulose content: 20.2% by mass). When the obtained bent plate was visually inspected, there were no cracks or splits on the surface, and the appearance was good.

[0053] Comparative Example 2-1 A bent plate was obtained by performing the same procedure as in Example 2-1, except that untreated bamboo material (hemicellulose content: 45.08% by mass) was used instead of processing bamboo material B1 (hemicellulose content: 20.2% by mass). When the obtained bent plate was visually inspected, cracks and splits were observed on the surface.

[0054] Comparative Example 2-2 A bent plate was obtained by performing the same procedure as in Example 2-1, except that processing bamboo material BB1 (hemicellulose content: 12.5% ​​by mass) prepared in Comparative Example 1-1 was used instead of processing bamboo material B1 (hemicellulose content: 20.2% by mass). When the obtained bent plate was visually inspected, cracks were observed on the surface.

[0055] Comparative Example 2-3 A bent plate was obtained by performing the same procedure as in Example 2-1, except that processing bamboo material BB2 (hemicellulose content: 33.8% by mass) prepared in Comparative Example 1-2 was used instead of processing bamboo material B1 (hemicellulose content: 20.2% by mass). When the obtained bent plate was visually inspected, cracks and splits were observed on the surface.

[0056] 3. Manufacturing and evaluation of bamboo molded products (2) The bamboo materials for processing obtained in Examples 1-4 and 1-5 were subjected to compression processing to produce molded products (bamboo spoons or bamboo coasters), and the appearance of each resulting molded product was evaluated.

[0057] Example 3-1 (Manufacturing of bamboo spoons) The bamboo material B4 for processing (hemicellulose content: 28.7% by mass) prepared in Examples 1-4 was placed in a constant temperature and humidity chamber and left to stand under conditions of 40°C and 90% humidity. After 48 hours, it was removed and its moisture content was reduced to 30%. Next, the bamboo material for processing 11 was subjected to compression processing using a spoon manufacturing mold, as shown in Figure 3, which comprises an upper mold 13 and a lower mold 15 and forms a spoon-shaped cavity with a length of approximately 160 mm when the mold is clamped, to obtain a bamboo spoon 24 that reflects the cavity shape (see Figure 4). Specifically, the spoon manufacturing mold was preheated to 120°C, the bamboo material for processing 11 was placed in a predetermined position on the lower mold 15, and the upper mold 13 was lowered at a speed of 5 mm per second to compress the bamboo material 11. The mold was clamped for 15 minutes, after which the mold temperature was cooled to approximately 30°C and demolded to obtain the bamboo spoon 24. Figure 5 shows an image of the front surface of the obtained bamboo spoon. As is clear from Figure 5, there were no cracks or splits on either side of the obtained bamboo spoon, and the bamboo fiber flow and color tone were good.

[0058] Example 3-2 (Manufacturing of bamboo spoons) The bamboo material B5X (hemicellulose content: 27.6% by mass) prepared in Example 1-5 was placed in a constant temperature and humidity chamber and left to stand under conditions of 40°C and 90% humidity. After 48 hours, it was removed and the moisture content was reduced to 30%. Next, using a spoon manufacturing mold, as shown in Figure 6, which includes an upper mold 13 and a lower mold 15 and forms a spoon-shaped cavity approximately 150 mm in length when clamped, two pieces of bamboo material B5X were stacked to form bamboo material 11A. This was then subjected to compression processing in the same manner as in Example 3-1 to obtain a bamboo spoon 26 that reflected the cavity shape (see Figure 7). Images of the front and back surfaces of the obtained bamboo spoon are shown in Figures 8 and 9, respectively. As is clear from these figures, there were no cracks or splits on either side of the obtained bamboo spoon, and the bamboo fiber flow and color tone were good.

[0059] Example 3-3 (Manufacturing of bamboo coasters) The bamboo material B5Y (hemicellulose content: 27.6% by mass) prepared in Example 1-5 was placed in a constant temperature and humidity chamber and left to stand under conditions of 40°C and 90% humidity. After 48 hours, it was removed and the moisture content was reduced to 30%. Next, using a coaster manufacturing mold, as shown in Figure 10, which includes an upper mold 13 and a lower mold 15, and which forms a cavity that is a rounded square (96mm x 96mm) plate when clamped and has a convex pattern on the inner surface of the mold to form a design pattern on both sides, the bamboo material 11 was subjected to compression processing in the same manner as in Example 3-1 to obtain a bamboo coaster 28 that reflects the shape of the cavity (see Figure 11). Images of the front and back surfaces of the obtained bamboo coaster are shown in Figures 12 and 13, respectively. As is clear from these figures, there were no cracks or splits on either side of the obtained bamboo coaster, and the bamboo fiber flow and color tone were good. [Industrial applicability]

[0060] The bamboo material for processing according to the present invention has good bamboo fiber flow and color tone, and is suitable as a material for manufacturing bamboo molded products that have excellent appearance. The bamboo molded product of the present invention, and composite products formed by integrating this bamboo molded product with other articles, are useful as everyday items (tableware, cutlery, trays, etc.), ornaments, decorative items, furniture, musical instruments, audio equipment, electrical products, vehicle interior parts, housing equipment, bathroom and toilet supplies, pet supplies, cosmetic tools, etc. [Explanation of Symbols]

[0061] 11: Bamboo lumber for processing 13: Upper mold 15: Lower mold 21: Bent plate 24: Bamboo spoon 26: Bamboo spoon 28: Take coaster

Claims

1. A bamboo material for processing, used as a raw material for manufacturing bamboo molded products by being subjected to molding processes, The bamboo material for processing is characterized in that the ratio of the total amount of monosaccharides derived from hemicellulose, excluding glucose, to the total amount of monosaccharides derived from constituent sugar components contained in the bamboo material for processing is 15 to 32% by mass.

2. A method for manufacturing a bamboo molded product, characterized by comprising a shaping step of subjecting the bamboo material for processing described in claim 1 to bending or compression processing.

3. A bamboo molded product characterized by being obtained by the method described in claim 2.

4. The bamboo molded article according to claim 3, comprising a coating on at least a portion of its surface.

5. A composite material characterized by being formed by integrating the bamboo molded product described in claim 3 with another article.

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