JP7280145B2 - Separation method of bamboo tissue - Google Patents

Description

The present invention relates to a method for separating fibers and parenchyma from bamboo material.

Bamboo material includes bamboo fibers consisting of vascular bundles and vascular bundle sheaths surrounding them, and a basic tissue consisting of parenchyma cells surrounding bamboo fibers. It is not easy to separate fibers (vascular bundle sheaths) and parenchyma from bamboo, and so far, steaming treatment, alkali treatment, or various mechanical processing treatments have been investigated. As one of the most common methods for separating bamboo fibers from bamboo, a steaming explosion treatment is known. However, in order to separate the fibers by this method, it is necessary to repeat the blasting treatment several times, and the bamboo fibers are easily damaged by the blasting. In addition, it is difficult to efficiently separate and recover the parenchyma cells of the bamboo material after the steaming and explosion treatment because the parenchyma cells are attached to the fibers in a wet state.

As a method for separating bamboo fibers from bamboo material without using blasting treatment, there is a method using machining. However, bamboo fibers separated from bamboo material by mechanical processing have short fiber lengths and tend to be uneven in length. The following patent documents 1 and 2 can be exemplified as documents disclosing a method for separating bamboo fibers from bamboo material without using blasting treatment.

Patent document 1 discloses a process of steaming vascular sheath fibers obtained from the steamed bamboo material with water, a process of crushing the steamed bamboo material to obtain vascular bundle sheaths, and obtaining fibers from the vascular bundle sheaths. Manufacturing by a method including steps is described. Patent Literature 1 describes crushing steamed bamboo by hitting it with a hammer to separate it into vascular bundle sheaths and parenchyma cells, and then stirring it with a mixer to defibrate it.

Patent Document 2 describes a method of bringing bamboo into contact with water vapor to loosen the bond between the parenchyma cells of bamboo and vascular bundle sheaths of bamboo fibers, and then removing the parenchyma to extract bamboo fibers. . In Patent Document 2, as a method for removing parenchyma cells, it is described that a bamboo material brought into contact with water vapor is massaged by hand or pressed with a roller to loosen it.

Conventionally, a method for separating and recovering parenchyma cells from bamboo has not been studied. Patent Documents 1 and 2 also remove the parenchyma cells to obtain fibers from the bamboo material, and do not describe separation of the parenchyma cells in a recoverable form.

JP-A-2008-23769 JP 2007-283661 A

Edited by Yu Ishimaru, Yuzo Furuta, Maki Sugiyama, "Wood Science Course 3, Physics of Wood", pp. 176-181, published by Kaiseisha

The method for separating bamboo fibers and parenchyma cells described in Patent Documents 1 and 2 is mainly aimed at extracting and using fibers from bamboo, and efficiently separating and recovering not only the fibers but also the parenchyma cells. The specific processing method of is not examined. In addition, the purpose of the collected fibers is not to recover the vascular bundle sheath from which long fibers can be obtained in good condition.

An object of the present invention is to provide a method for efficiently separating and recovering fibers (vascular bundle sheaths) and parenchyma cells from bamboo in good condition with little damage.

In the present invention, as a means for achieving the above object, there is provided a method for separating fibers and parenchyma cells from bamboo material, comprising:
a steam treatment step of treating a bamboo material having a minimum width of 1 mm or more on a cross section perpendicular to the direction along the fiber with steam;
a drying process for drying the bamboo material after the steam treatment;
a tissue separation step of applying a compressive force to the dried bamboo material in a direction perpendicular to the direction along the fibers to separate the fibers and the parenchyma cells;
to provide a method comprising:

In the method of the present invention, steam treatment of bamboo decomposes some of the adhesive components between cell tissues that make up the bamboo. occurs, promoting detachment between tissues. As a result, the tissue separation of the bamboo material by final mechanical processing can be performed under mild conditions, and the tissue is less likely to be damaged. In addition, since the bamboo material is machined in a dry state, it is very easy to separate and recover the vascular bundle sheath and parenchyma cells.

More preferably, the method of the present invention further includes a hot water treatment step of soaking the steamed bamboo in hot water to extract and remove water-soluble components between the steam treatment step and the drying step. According to this aspect, it is easy to remove the water-soluble component generated by the decomposition of the component that binds the tissue in the steam treatment step, and it is easy to separate the fibers and the parenchyma cells in the tissue separation step.

In the method of the present invention, it is more preferable that the bamboo material includes the entire thickness direction of the bamboo culm wall and the circumferential direction of the bamboo culm wall on a cross section perpendicular to the direction along the fiber before the steam treatment step. has a width of 20 mm or more. When bamboo material of this size is used, the internal stress generated during the drying process is increased, so that the fibers and parenchymal cells can be separated more easily in the tissue separation process.

The method of the present invention more preferably uses a bamboo that has been pre-dried before the steaming step as the bamboo. According to this aspect, the hemicellulose of the bamboo material can be decomposed by steam treatment for a relatively short period of time.

INDUSTRIAL APPLICABILITY According to the method of the present invention, fibers (vascular bundle sheaths) and parenchyma cells can be efficiently separated and collected from bamboo in good condition with little damage.

FIG. 1 shows the FT-IR spectra of bamboo treated with steam for 0.5 hours or 2 hours of dry bamboo and untreated bamboo. FIG. 2 shows photographs of shapes 1 (cut into pieces), shapes 2 (shredded), and shapes 3 (strands) of bamboo before steam treatment in Experiment 2. FIG. The upper part of FIG. 3 is a photograph of the dried bamboo of shapes 1 to 3 after being subjected to the treatment of step 1 including steam treatment for 2 hours and step 2 including drying after that. The lower part of FIG. 3 shows the results when dried bamboo materials of shapes 1 to 3 were subjected to step 1 including steam treatment for 2 hours, step 2 including subsequent drying, and step 3 including subsequent hot water treatment. It is a photograph of bamboo material after processing. The upper part of FIG. 4 is a photograph of undried bamboo materials of Shapes 1 to 3 after being subjected to the treatment of step 1 including steam treatment for 2 hours and step 2 including subsequent drying. The lower part of FIG. 4 shows the undried bamboo materials of Shapes 1 to 3 subjected to Step 1 including steam treatment for 2 hours, Step 2 including subsequent drying, and Step 3 including subsequent hot water treatment. 1 is a photograph of bamboo material after the treatment of . “After steam treatment” in FIG. 5 corresponds to 2.2.1. The steam treatment time in (2) of (2) was set to 3 hours, and the experiment 3, 2.2.1. (1) to (4) (steam treatment + drying treatment) are shown. 2.2.1. (1) to (7) (steam treatment+drying treatment+hot water treatment+drying treatment) of bamboo material. FIG. 6 shows the relationship between the steam treatment time and the moisture content of bamboo in Experiment 3. FIG. 7 shows the relationship between the steam treatment time in Experiment 3 and the weight reduction rate of the bamboo material in steam treatment and hot water treatment. FIG. 8 shows a photograph of the exit side of the roll press when the steam-treated bamboo (steamed + hot water + dried) in Experiment 3 was roll-pressed. FIG. 9 shows photographs of bamboo fiber after roll-pressing dried bamboo material for each steam treatment time (30 minutes, 1 hour, 2 hours, 3 hours) in Experiment 3. The left side of FIG. 10 shows a photograph of finely powdered parenchyma cells separated from fibers when the steam-treated bamboo obtained in Experiment 3 (one-hour steam treatment + hot water treatment + drying treatment) was roll-pressed. . The right side of FIG. 10 is a 200-fold enlarged photograph of the finely powdered parenchyma cells shown in the left side of FIG. FIG. 11 shows photographs of bamboo fibers after roll-pressing undried bamboo material for each steam treatment time (30 minutes, 1 hour, 2 hours) in Experiment 3.

<Bamboo shape>
The culm of bamboo has a hollow cylindrical structure, and the part surrounding the hollow part is the culm wall. Nodes are arranged at different positions in the axial direction of the bamboo culm. The culm wall consists of the outer epidermis (skin), the inner medullary layer, and the central pillar between the epidermis (skin) and the medullary layer. The epidermis of the culm wall is composed of epidermal cells and subepidermal cells. The central column consists of a basic tissue composed of parenchyma cells, a vascular bundle composed of ductal and sieve cells, and a vascular bundle composed of bast fiber cells surrounding the vascular bundle. Bamboo fibers consist of a vascular bundle and a vascular sheath surrounding it. The bamboo fibers are oriented substantially parallel to the axial direction of the bamboo culm and impart splitting properties to the culm wall. The structure of bamboo is described in detail in Non-Patent Document 1.

One of the characteristics of the present invention is that the bamboo used in the steam treatment step has a shape with a minimum width of 1 mm or more on a cross section perpendicular to the direction along the fibers.

As described above, bamboo fiber consists of vascular bundles and vascular bundle sheaths surrounding them. Since the diameter of the bamboo fiber is about 0.5 mm, the bamboo material having the above shape includes the entire diameter direction of the bamboo fiber. In the bamboo material having the above shape, the overall shape of the bamboo material is difficult to change in the drying process after the steam treatment process, which will be described later, and internal stress is likely to accumulate inside the bamboo material. Furthermore, as will be described later, components such as hemicellulose, which bonds the tissue of fibers and the tissue of parenchyma in bamboo, are decomposed by the steam treatment process. Therefore, in the bamboo that has been dried after the steam treatment process, the internal stress promotes the separation of the tissue of the fibers and the tissue of the parenchyma, and the fibers and the parenchyma are efficiently separated and collected from the bamboo. can do.

The minimum width of the bamboo material used in the present invention is preferably 2 mm or more, more preferably 3 mm or more, more preferably 5 mm or more, still more preferably 5 mm or more. The larger the narrow width, the larger the internal stress, which is preferable. The bamboo material used in the present invention is more preferably a bamboo material whose longitudinal direction is the direction along the fiber. The bamboo material used in the present invention is more preferably the width of the bamboo culm wall in the circumferential direction on a cross section that includes the entire thickness direction of the bamboo culm wall and is perpendicular to the direction along the bamboo fiber before the steam treatment step. is preferably 20 mm or more, more preferably 30 mm or more, more preferably 100 mm or less, more preferably 50 mm or less. When a bamboo material of this size is used, the internal stress tends to increase, and the tissue cells of the bamboo material are easily separated in the tissue separation process.

The bamboo material used in the present invention may be a bamboo material in a wet state (that is, a raw bamboo material) before the steam treatment process, or may be a bamboo material that has been dried in advance. It is dried bamboo. If bamboo that has been dried in advance is used, the steam will quickly act on the inside of the bamboo in the steam treatment process, and thus the decomposition of hemicellulose will easily proceed in the steam treatment process.

The pre-dried bamboo may be, for example, bamboo with a moisture content of 10% by weight or less, preferably 5% by weight or less.

<Steam treatment process>
The steam treatment step is a step of treating the bamboo in the shape described above with steam. In this process, components such as hemicellulose, which bonds the fibers and parenchyma cells in the bamboo, are decomposed by water vapor, and the separation of the tissue in the bamboo is promoted.

The water vapor is preferably water vapor with a temperature range of 160°C or higher and 200°C or lower, more preferably 170°C or higher and 190°C or lower.

Although the pressure of steam is not particularly limited, it is preferably 0.6 MPa or higher, more preferably 0.8 MPa or higher, preferably 1.6 MPa or lower, and more preferably 1.3 MPa or lower.

The steam treatment time is not particularly limited, but is preferably 20 minutes or longer, more preferably 30 minutes or longer, still more preferably 1 hour or longer, particularly preferably 2 hours or longer, preferably 10 hours or shorter, more preferably 5 hours or shorter. is.

<Drying process>
The drying step is a step of drying the bamboo material after the steam treatment. Surprisingly, the present inventors found that when a bamboo material of a predetermined size is treated with steam to decompose hemicellulose and the like and then dried, internal stress is generated inside the bamboo material, and the bamboo material can be easily separated into fibers in the subsequent tissue separation process. It was found that the parenchyma cells were separated and the respective tissues could be separated and recovered.

In the drying step, the bamboo material is dried to a moisture content of, for example, 10% by weight or less, preferably 5% by weight or less.

<Hot water treatment process>
In a preferred embodiment of the present invention, it is preferable to further include, between the steaming process and the drying process, a hot water treatment step of soaking the steamed bamboo material in hot water to extract and remove water-soluble components.

By performing the hot water treatment step, the water-soluble component generated by the decomposition of the component that binds the fibers by the treatment with steam is extracted and removed in the hot water, so it is difficult to use in the drying step and the tissue separation step. Separation of the fibers and the parenchyma is further facilitated, and it becomes easier to obtain the fibers and the parenchyma from the bamboo material.

Hot water is, for example, water at 80° C. or higher, preferably 85° C. or higher, more preferably 90° C. or higher, and although the upper limit is not particularly limited, it is usually water at a temperature of less than 100° C. under normal pressure.

In the hot water treatment step, the bamboo material after the steam treatment is preferably soaked in hot water for 30 minutes or longer, more preferably 60 minutes or longer, and more preferably 90 minutes or longer. Hot water may be replaced as appropriate.

A drying step can be performed after the hydrothermal treatment step.

Moreover, a drying step for drying the bamboo material may be further included between the steam treatment step and the hot water treatment step. The drying process in this case can be performed under the same conditions as the drying process described above.

<Tissue Separation Process>
The tissue separation step is a step of applying a compressive force to the dried bamboo material in a direction perpendicular to the direction along the fibers to separate the fibers and the parenchyma cells. At the end of the drying process, the force that binds the vascular bundle sheath and parenchyma cells of the bamboo material is sufficiently reduced, so in the tissue separation process, the bamboo fibers and parenchyma cells can be easily separated by simply applying a relatively small compressive force to the bamboo material. can be separated and taken out.

In the tissue separation step, preferably, the dried bamboo material is treated with a roll press so that a compressive force is applied in a direction perpendicular to the direction along the fibers. Other means for applying compressive force in directions perpendicular to the fiber include flat plate presses, roll crushers, and hammer crushers.

The separated fibers and parenchyma cells can be collected and used individually.

The bamboo fibers separated and recovered according to the present invention can be used to form building materials such as boards in which fibers are accumulated, and bedding mats.

Bamboo parenchyma cells separated and collected by the present invention are porous granular substances having substantially uniform dimensions and shapes. Since hemicellulose is decomposed in the parenchyma, the parenchyma contains resin components such as lignin in the parenchyma in an easily extractable form. In addition, since the parenchyma has decomposed hemicellulose, the parenchyma contains the components of the parenchyma in a form that can be easily used by animals and plants. Therefore, the parenchyma cells can be used as a water absorbing material, a raw material for producing a bamboo-derived resin component, a feed component, a fertilizer component, and the like.

<Experiment 1: Analysis of structural change when bamboo is steam-treated>
1. Purpose From Experiment 2 onwards, it was confirmed that it was possible to extract fibers and parenchyma cells by steaming bamboo material. The reason for this is thought to be the influence of changes in the constituents of the bamboo during the steam treatment of the bamboo. Therefore, in this experiment, the steam-treated bamboo material is analyzed by FT-IR to confirm the change in the composition of the bamboo material due to the steam treatment.

2. Test A piece of dried bamboo (moisture content of 1-2%) was prepared. These dry bamboo materials were steam-treated in a small pressure-resistant container under two conditions: a steam pressure of 1 MPa (temperature of 180°C) and a treatment time of 0.5 hours and a treatment time of 2 hours. A test body was prepared. A hot water-treated bamboo material was used as an untreated sample (BM).

(1) Preparation of powder for FT-IR analysis Each specimen was ground with an electric grinder to prepare powder. At this time, the entire bamboo (outer skin, inner skin, and inside) was scraped evenly to recover the powder.

(2) FT-IR measurement (tablet method)
About 4 mg of each test powder and about 200 mg of KBr dried at 130 ° C. are ground while being mixed in an agate mortar, tablets are prepared with a disc molding machine, and FT-IR measurement is performed with FT / IR-4100 (Jasco). bottom. In addition, background measurement was performed on a KBr tablet alone (produced with 200 mg of KBr), and corrections for CO ₂ and H ₂ O were performed to confirm the results.

(3) Acquisition of bamboo holocellulose and bamboo cellulose and FT-IR analysis On the other hand, holocellulose (a mixture of hemicellulose and cellulose) and cellulose were separated from the defatted bamboo sample by the method described in “Wood Science Experiment Manual (Buneidou Publishing)”. , and the FT-IR spectrum was obtained under the same conditions as above.

3. Results FIG. 1 shows the FT-IR spectra of dried bamboo that was steam-treated for 0.5 hours or 2 hours.

It was confirmed that the peak at 1735 cm ⁻¹ and the peak at 1245 cm ⁻¹ decreased due to the steam treatment. It was confirmed that most of these peaks disappeared after 2 hours of steaming.

On the other hand, bamboo holocellulose shows characteristic absorption peaks near 1735 cm ^-1 and 1245 cm ^-1 , whereas bamboo cellulose does not have absorption peaks at these positions. Since bamboo holocellulose is a mixture of hemicellulose and cellulose, it was confirmed that bamboo hemicellulose exhibits specific absorption peaks near 1735 cm ⁻¹ and 1245 cm ⁻¹ .

From the above results, it was shown that steam treatment of bamboo reduced hemicellulose, and that hemicellulose almost disappeared after 2 hours of steam treatment.

<Experiment 2: Investigation of the influence of bamboo shape before steam treatment on tissue separability>
(Summary of results)
Bamboo materials with different shapes (sizes) were subjected to steam treatment, and the separability of the bamboo structure was evaluated. As a result, the following was confirmed.
・Bamboo that is to be steam treated has a certain size, such as small pieces or shredded pieces, so that the separation of the structure is easier to progress during the treatment.
・Bamboo material that has been steamed for 2 hours at a steam pressure of 1 MPa (equivalent to a temperature of 180°C) is boiled and dried after the steam treatment to further promote the separation of fibers and parenchyma cells.

(detail)
1. Purpose Bamboo fibers and parenchyma were separated by steam treatment. In addition, we investigated the effect of different shapes (dimensions) of bamboo on the separability of the tissue.

2. Test 2.1. Specimen Type of bamboo material: Moso bamboo Shape of bamboo material:
(Shape 1) Subdivided material: Width 30 mm in the circumferential direction of the bamboo stalk wall and length 70 mm in the fiber direction perpendicular to the fiber direction,
(Shape 2) Shredded material: Width around 3 mm in the circumferential direction of the bamboo culm wall perpendicular to the fiber direction × length in the fiber direction 70 mm,
(Shape 3) Strand: Width around 0.3 mm perpendicular to the fiber direction and in the circumferential direction of the bamboo culm wall x length in the fiber direction 70 mm
Moisture content of bamboo material before steam treatment: (1) Dried material (4.8% moisture content, dried at 80°C), (2) Undried material (average moisture content 42.8%)
Others: No pretreatment such as hot water extraction of bamboo material.

FIG. 2 shows a photograph of the shape 1 (small pieces), shape 2 (shredded material), and shape 3 (strand) before the steam treatment.

2.2. Test method Steam treatment and treatment conditions of bamboo were evaluated.
Bamboo materials with different shapes and moisture contents were steam-treated using a small pressure vessel, and the state after treatment was observed.

A part or all of the following three processes were performed on the bamboo specimen.
Step 1 (steam treatment): Steam treatment was performed at a steam pressure of 1 MPa (equivalent to a steam temperature of 180° C.) for 30 minutes and 2 hours.
Step 2 (drying): The bamboo material after the steam treatment in step 1 was dried at 80°C, and the condition after the steam treatment was observed.
Step 3 (hot water treatment): The steam treated material dried in step 2 was boiled in water for 2 hours, dried at 80°C, and then observed after the hot water treatment.

3. Results Figures 3 and 4 show the results of the state change due to steam treatment of bamboo.
The upper part of FIG. 3 is a photograph of the dried bamboo of shapes 1 to 3 after being subjected to the treatment of step 1 including steam treatment for 2 hours and step 2 including drying after that.

The lower part of FIG. 3 shows the results when dried bamboo materials of shapes 1 to 3 were subjected to step 1 including steam treatment for 2 hours, step 2 including subsequent drying, and step 3 including subsequent hot water treatment. It is a photograph of bamboo material after processing.

The upper part of FIG. 4 is a photograph of undried bamboo materials of Shapes 1 to 3 after being subjected to the treatment of step 1 including steam treatment for 2 hours and step 2 including subsequent drying.

The lower part of FIG. 4 shows the undried bamboo materials of Shapes 1 to 3 subjected to Step 1 including steam treatment for 2 hours, Step 2 including subsequent drying, and Step 3 including subsequent hot water treatment. 1 is a photograph of bamboo material after the treatment of .

The results shown in FIGS. 3 and 4 reveal the following.

For wood pieces that have been steamed for 2 hours and dried (steps 1+2), cracks and tissue detachment have occurred in the epidermis and inner bark of the bamboo, regardless of whether pre-dried or undried wood is used. occurred.

Bamboo that was steamed and dried for 2 hours (steps 1 + 2) was compared to bamboo that was steamed for 2 hours, dried and treated with hot water (steps 1 + 2 + 3). A clear change of state was observed regardless of the use. Specifically, in addition to Steps 1+2, Step 3 was further performed, which clearly accelerated the progress of the separation between bamboo fibers and parenchyma cells.

In addition, when the bamboo wood cut into small pieces or shredded is subjected to steam treatment, drying and hot water treatment (steps 1 + 2 + 3) for 2 hours, the dried material (Fig. 3 lower left, middle lower) is better than the undried material 4 lower left, lower middle), the separation between fibers and parenchyma cells was remarkably promoted.

On the other hand, the dried or undried bamboo strands were subjected to steam treatment and drying (steps 1+2) for 2 hours (Fig. 3 upper right, Fig. 4 upper right) and 2 hours steam treatment, drying and hot water treatment ( When steps 1+2+3) were performed (lower right in FIG. 3 and lower right in FIG. 4), the strand itself was deformed and the separation between the fibers and the parenchyma cells was slight.

From the above results, it was shown that the separation of bamboo fibers and parenchyma cells was more pronounced when dried bamboo was used than undried bamboo. Regarding the shape (size) of the bamboo material, it was shown that bamboo fibers of a certain size, such as finely chopped material and shredded material, facilitate separation of bamboo fibers from other tissues.

<Experiment 3: Investigation of the effect of bamboo steam treatment time and moisture content on separation processability>
(Summary of results)
A detailed study was carried out on the state change when bamboo was treated with steam, and the following things were confirmed.
・The ratio of components that were decomposed by steaming and became soluble in hot water and eluted from the bamboo material was 26-30%, and reached that ratio in about 1 hour of steaming.
We investigated the effect of the moisture content of the steamed bamboo when separating it with a roll press machine, and confirmed the following.
・When steam-treated bamboo was dried after steam treatment and then roll-pressed, it was possible to separate the fibers and parenchyma cells regardless of the steam treatment time (30 minutes to 3 hours).
・When steam-treated bamboo is roll-pressed without being dried after steam treatment, the separation between fibers and parenchyma cells is poor, and fiber breakage occurs.

(detail)
1. Purpose In experiment 2, it was confirmed that when steam treatment is performed for the purpose of separating bamboo fibers and parenchyma cells, tissue separation proceeds efficiently by using pre-dried small pieces of wood. In this experiment, the effect of steam treatment time on the state change of bamboo will be examined in detail.

In addition, the effect of the moisture content on the tissue separability of bamboo after steam treatment before the tissue separation by mechanical processing (such as roll press processing) is examined.

2. Test 2.1. Specimen Type of bamboo: Moso bamboo Shape: Small pieces, perpendicular to the fiber direction and in the circumferential direction of the bamboo culm wall 30 to 35 mm in width × 9 to 12 mm in thickness of the bamboo culm wall × 160 mm in length in the fiber direction
Moisture content: Dry material dried before steam treatment (completely dry, dried at 105°C)

2.2. Test method 2.2.1. Evaluation of state change of bamboo due to steam treatment (1) Preparation for test: Bamboo cut into small pieces dried at 105°C was prepared and the total dry weight was confirmed.
(2) Steam treatment: Bamboo material was treated under four conditions: steam pressure 1 MPa (equivalent to steam temperature 180° C.), treatment time 30 minutes, 1 hour, 2 hours, and 3 hours.
(3) Weight measurement: In order to confirm the moisture content of the bamboo material immediately after the steam treatment, the weight was measured immediately after the treatment.
(4) Drying: The treated bamboo was dried at 105°C and the weight was measured in order to evaluate the change in moisture content and weight loss rate associated with the steam treatment.
(5) Observation: A change in the state of the bamboo due to the steam treatment was confirmed.
(6) Hot water treatment: The dried steamed bamboo was boiled in water for 2 hours to remove hot water soluble components.
(7) Weight measurement: Bamboo was dried at 105°C and weighed in order to evaluate the weight reduction rate of the bamboo due to the hot water treatment.
(8) Observation: A change in the condition of the bamboo material after the hot water treatment was confirmed.

The observation results of the bamboo "after steam treatment" described later show the observation results in (5) above for the bamboo that was subjected to the treatments (1) to (4) (steam treatment + drying treatment).

The observation results of the bamboo material "after steam treatment + hot water treatment + drying" described later show that the bamboo material subjected to the treatments (1) to (7) (steam treatment + drying treatment + hot water treatment + drying treatment) The observation results in (8) above are shown.

2.2.2. Evaluation of machinability of steam-treated bamboo (dry wood) The steam-treated bamboo (steam treatment + hot water treatment + drying treatment) subjected to the above treatments (1) to (7) was machined using a roll press machine. , evaluated the separability of fibers and parenchyma.

2.2.3. Evaluation of machinability of steam-treated bamboo material (undried material) After the steam-treated bamboo material subjected to the treatments (1) to (3) above was naturally cooled, the above 2.2.2. In the same way as in , we processed with a roll press machine and evaluated the separability of fibers and parenchyma cells.

3. Results 3.1. Evaluation of state change due to steam treatment of bamboo material "After steam treatment" in Fig. 5 indicates that the steam treatment time in (2) is 3 hours, and the treatments in (1) to (4) (steam treatment + drying treatment). FIG. 5, “after steam treatment + hot water treatment + drying”, is the same steam treatment time, and the above (1) to (7) treatments (steam treatment + drying treatment + hot water treatment) are shown. A photograph of a bamboo material subjected to treatment + drying treatment) is shown.

It was shown that the shape of the bamboo collapsed and the separation of the tissue containing the parenchyma cells from the fibers progressed by drying the bamboo after steam treatment. Furthermore, it was shown that steam treatment, drying, further hydrothermal treatment, and subsequent drying of the bamboo pieces further facilitated the separation of fibers from tissue containing parenchyma cells.

3.2. Evaluation of moisture content change by steam treatment of bamboo 3.2.1. Change in moisture content of bamboo due to steam treatment From the weight of bamboo immediately after steam treatment (water content) measured in (3) above and the weight of bamboo dried after steam treatment (dry weight) measured in (4) above, , the moisture content was determined.

FIG. 6 shows the relationship between the steam treatment time in (2) and the moisture content of bamboo. It was confirmed that steam treatment of bamboo increased the moisture content to around 50%.

3.2.2. Weight reduction rate of bamboo by steam treatment and hot water treatment (proportion of hot water soluble content)
Based on the total dry weight of bamboo before treatment measured in (1) above and the weight of bamboo dried after steam treatment and hot water treatment measured in (7) above, weight of bamboo after steam treatment and hot water treatment Decrease rate was calculated.

FIG. 7 shows the relationship between the steam treatment time in (2) above and the weight reduction rate of bamboo through steam treatment and hot water treatment.

It was confirmed that the weight reduction rate of the bamboo material was a substantially constant value of 26 to 30% after one hour or more of steam treatment. Since the ratio of bamboo components that became soluble in hot water by steam treatment is equivalent to the ratio of hemicellulose in bamboo (around 30%), it can be said that the hemicellulose in bamboo solubilized by steam treatment was extracted by hot water treatment. Presumed.

3.3. Separability evaluation by roll press processing of steam-treated bamboo (dry material) 3.3.1. Situation of separation by roll press processing of dried bamboo after steam treatment 2.2.2. 8 shows a photograph of the exit side of the roll press when the steam-treated bamboo material (steam treatment + hot water treatment + drying treatment) subjected to the treatments (1) to (7) above is roll-pressed.

The steam-treated bamboo material was discharged with the fibers and parenchyma separated when passing through the roll press. The parenchyma cells fell as fine powder under the roll during roll press processing and could be easily collected.

FIG. 9 shows photographs of bamboo fibers after roll-pressing for each steam treatment time (30 minutes, 1 hour, 2 hours, and 3 hours) in (2) above. Straight bamboo fibers could be separated and recovered from parenchyma cells through roll-press processing, regardless of the steam treatment time.

The left side of FIG. 10 shows the fine powder separated from the fiber when the steam-treated bamboo material (one-hour steam treatment + hot water treatment + drying treatment) subjected to the treatments (1) to (7) above is roll-pressed. A photograph of a parenchymal cell having a shape is shown. The right side of FIG. 10 is a 200-fold enlarged photograph of the finely powdered parenchyma cells shown in the left side of FIG. The separated parenchyma cells were collected as a uniform fine powder having a size of about 100 μm and having a relatively uniform shape and size.

3.3.2. Situation of separation by roll press processing of undried bamboo after steam treatment 2.2.3. In step (1) to (3) above, the steam-treated bamboo material was naturally cooled and then roll-pressed in an undried state.

FIG. 11 shows photographs of bamboo fibers after roll-pressing for each steam treatment time (30 minutes, 1 hour, and 2 hours) in (2) above. When the steam-treated bamboo was roll-pressed in an undried state with a high moisture content, the separation between the bamboo tissue and the parenchyma did not proceed sufficiently, and fiber breakage occurred. Moreover, when roll pressing was performed in an undried state, part of the structure of the bamboo adhered to the roll surface during processing.

Claims (4)

A method for separating fibers and parenchyma cells from bamboo, comprising:
a steam treatment step of treating a bamboo material having a minimum width of 1 mm or more on a cross section perpendicular to the direction along the fiber with steam;
a drying process for drying the bamboo material after the steam treatment;
a tissue separation step of applying a compressive force to the dried bamboo material in a direction perpendicular to the direction along the fibers to separate the fibers and the parenchyma cells;
method including. Between the steaming process and the drying process,
2. The method according to claim 1, further comprising a hot water treatment step of immersing the steamed bamboo in hot water to extract and remove water-soluble components. Before the steam treatment process, the bamboo material has a shape that includes the entire thickness direction of the bamboo culm wall and has a width of 20 mm or more in the circumferential direction of the bamboo culm wall on a cross section perpendicular to the direction along the fiber. 3. A method according to claim 1 or 2. A method according to any one of claims 1 to 3, wherein the bamboo material is pre-dried bamboo material prior to the steaming step.

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