JP2005103936A - Dry pressing method for bamboo fabric - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ecological dry pressing method for a bamboo fabric which uses a fabric manufactured not by a conventional wet paper making method using a pulp liquid but by a dry fabric processing method producing no waste liquid in a fabric processing process, and does not use water. <P>SOLUTION: When a raw bamboo material is defibrated to obtain a long fiber part which is not powdery nor granular, and the fiber part is hot-pressed to make a bamboo sheet (bamboo press paper), the fiber part can be hot-pressed without adjusting moisture by drying. The occurrence of a burn by heat, a stain related to water vapor, and a blister (defective bonding) on the surface and back of the sheet is prevented. Hygroscopic starch, which is a similar substance to saccharides, about 2% in weight ratio is added in order to avoid the influence of saccharides contained as much as 20% in the bamboo fabric. Alternatively, the fine powder of polyvinyl alcohol which demonstrates viscosity by moisture absorption is added as a bonding agent. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a dry molding method of bamboo fiber material, and in particular, an adhesive is added to a fiber material obtained by dry-disassembling bamboo that has been chopped in advance with a coarse crusher and a pulverizer. The present invention relates to a method for hot-pressing and a method for producing a bamboo molded product produced using the method.

Bamboo has a strength comparable to that of timber, and is promising as a raw material for structural materials because it can be bred in a relatively low mountain range and easily cut down. Patent Document 1 discloses a technique for obtaining a bamboo fiber and a fibrous vascular bundle that is an aggregate of the bamboo fiber by mechanical processing. About 80% of the fiber material can be obtained by the two-stage defibrating method including the drum impact defibrator shown here. Patent Document 2 discloses that a defibrating method comprising a first step of a crusher, a second step using a repelling machine, and a third step using a turbo mill can obtain substantially the same result as the previous method. It is shown. It has been described that cheap bamboo fibers can be used for building materials, fillers, reinforcing materials, livestock feeds, etc., using the fiber materials thus obtained.
Japanese Patent No. 2879979 JP-A-5-138617

  Technology for mixing defibrated waste paper with plastics has been established, promoting the use of recovered plastics. Therefore, after creating a defibrated material using a defibrating and crushing machine marketed using bamboo, the bamboo fiber material can be used as a plastic filler by mixing with a general resin. However, bamboo fiber is used as the main component of dry molding, and it has not been successfully used as a sheet-like single fiber or single molded product.

  Bamboo, which is abundant in Japan, was industrially used as a raw material until around 1965. Bamboo pulp that was chemically digested using bamboo was produced in Japan, and bamboo paper was made using Japanese paper techniques. There was to be. However, the production of chemical pulp using bamboo has declined because it is impossible to compete with wood pulp from imported wood chips and imported wood pulp in terms of cost.

  In this way, bamboo cannot continue to be used as an industry, and bamboo continues to increase in mountainous and hilly areas in Japan, resulting in a state of erosion of flat houses. This is unusual when the forest area is decreasing, and considering the fact that the production of bamboo has declined drastically since the end of the 1980s, it is a natural phenomenon because bamboo forests have become unmanaged more than forests. It is said that it is. Under such circumstances, various attempts have been made mainly by domestic machine makers to produce fibers only by mechanical processing rather than chemical cooking.

  In the background of this attempt, paying attention to the fact that the components of bamboo are lignin, which is a fiber binding component, is about half that of wood, and the bonding force between fiber objects is not as strong as wood, so it is easy to machine. Several manufacturers have succeeded in industrially producing dry and machined textiles. However, industrially, only the uses for building materials, fillers, and reinforcing materials are assumed. In other words, even if the bamboo material is successfully made into a fiber material, the state where the wood fiber which is advantageous in terms of strength and price cannot be beaten continues.

  Therefore, the present invention is a material that is not found in wood if it can easily make a molded product by taking advantage of the fact that there is a lot of sugar due to the small amount of lignin, which is a characteristic of bamboo that is not found in defibrated and crushed materials of wood. As a part of this molded product, there is a thin paper-like bamboo sheet. It is an object of the present invention to find a method for forming a bamboo sheet having characteristics as an analog of paper.

  The environmentally friendly bamboo fiber that does not use water by using a fiber material made by a dry fiberization method that does not generate waste liquid during the fiberization process, rather than the wet papermaking method that uses pulp liquid, which is a conventional paper manufacturing method. It is to provide a dry molding method.

  In order to solve the problem, the present invention maintains a bamboo fiber at a high moisture content, and when heated, excess moisture is released as water vapor, but a hot plate that is considered to contain a large amount of saccharides and In order to obtain an appearance and sheet strength that can be used as a bamboo sheet by preventing scorching (burning), staining, and swelling of the contact surface of bamboo, unsorted bamboo fiber material that has been defibrated to the vascular bundle level This is a dry molding method of bamboo fiber material in which a hygroscopic thermoplastic resin is added and hot pressed to a raw material to be used as it is, or a selected bamboo fiber material from which defibrated material and powdered fine fibers have been removed.

  Furthermore, the present invention is a molding method in which the hygroscopic thermoplastic resin is a hot-pressing material for bamboo defibrated material, which is a general thermoplastic resin and a hygroscopic material, and a dry molded product of bamboo defibrated material such as bamboo sheet. .

Further, the present invention is a dry molding method for bamboo defibrated material, wherein the molding temperature is 100 ° C. or more and 140 ° C. or less and pressing is performed at a pressure of 0.5 kg / cm ² or more. .

Further, in the present invention, the temperature of the upper heating plate is 100 ° C. or more and 130 ° C. or less, the temperature of the lower heating plate is 110 ° C. or more and 140 ° C. or less, and 0.5 kg / cm ² or more. It is a dry forming method of bamboo defibrated material, characterized by pressing with pressure.

  In molded products such as bamboo sheets made by heat-pressing high moisture content fibers made of vascular bundles made by defibrating bamboo with high moisture content, hygroscopic fine particles such as starch are added in addition to thermoplastic resin as a binder. By including or selecting a hygroscopic resin as a thermoplastic resin and blending it, it is possible to solve the problem of scorching at the time of hot pressing due to containing a large amount of sugar.

  By holding bamboo fiber at a high moisture content and heating it, excess moisture is released as water vapor, but the contact surface with the hot plate that seems to involve a large amount of sugar is burned, stained In order to prevent the occurrence of blistering and obtain an appearance and sheet strength that can be used as a bamboo sheet, raw materials that use unselected bamboo fiber material that has been defibrated to the vascular bundle level, or undefibrated material and powder This is a dry molding method for bamboo fiber products obtained by adding a hygroscopic thermoplastic resin to a selected bamboo fiber product from which fine fibers have been removed, and then hot pressing.

  Further, one embodiment of the present invention will be described in detail. An unselected bamboo raw material using a bamboo defibrated material in which the moisture content of the defibrated material obtained through the refining process is about 25% or more, or It is possible to form a molding raw material by adding a thermoplastic resin and a hygroscopic material to a selected bamboo raw material from which the non-defibrated material that is an impurity and powdered fine fibers have been removed from the fine material, and then forming it into an arbitrary shape by hot pressing It consists of the dry molding method of the characteristic bamboo fiber thing.

  Further, another embodiment of the present invention will be described in detail. Unsorted bamboo raw materials that use bamboo defibrated material that has passed through the defibrating process as it is or finely powdered with non-defibrated material that is an impurity from the defibrated material The method comprises a bamboo fiber material dry molding method characterized in that a molding raw material obtained by adding a hygroscopic thermoplastic resin to a selected bamboo raw material from which fibers have been removed and mixed is formed into an arbitrary shape by hot pressing.

Further, these inventions are characterized in that the molding raw material is heated at a temperature of 140 ° C. or lower and 100 ° C. or higher and pressed at a pressure of 0.5 kgf / cm ² or higher.

  And these inventions are characterized in that the lower heating plate is heated at a temperature of 140 ° C. or lower and 110 ° C. or higher, and the upper heating plate is heated at a temperature of 130 ° C. or lower and 100 ° C. or higher. It is a dry molded product of bamboo defibrated.

  And as a machine for obtaining a defibrated bamboo fiber material, a continuous device used as a used paper defibrating machine such as newspaper was used. Before putting into this machine, bamboo is chopped into small pieces and adjusted to the size corresponding to the processing capacity of the machine. This is a pretreatment step that is usually performed using an extrusion-type dividing device or the like used to bake bamboo charcoal so that it is easily crushed, and this is the first step.

  Next, a vertical rotating drum type crusher (manufactured by West Japan Technological Development (Yes)) is used for the machine in the second step for rough crushing. In the next important third step, a pin mill (“Fiber Laser” from West Japan Technology Development Co., Ltd.) is used. Rather than hitting a small piece of bamboo produced in the second step (mainly the size of a matchstick) between the rotating pin and the fixed pin of the machine until it becomes powdery, peel off the fibers without breaking long fibers It is processed using a precision crusher with a pin that has been arranged in a structure that generates a strong force and the shape of the pin adjusted.

  In these mechanical treatments, the pore size of the screen and the water content of the bamboo are important, and as a result of various tests, it has been found that the following combination conditions enable good fiberization.

良好な繊維化ができた解繊条件は伐採直後の竹を使用した場合で、第二工程の粗砕機のスクリーン径は２０ミリにし、第三工程の精砕機のスクリーン径は４ミリの場合であった。この条件で繊維化ができた最大の原因は最終の精砕機で摩擦熱により繊維を切らずに剥離させる作用を生じさせるには竹材の水分を６０％以上に含ませた繊維間・維管束間が弱い結合状態になっていること、また水分が多いことで維管束に弾性があり柔軟であることが重要になっていると推察される。

The defibrating conditions that resulted in good fiberization were when bamboo was used immediately after logging, the screen diameter of the crusher in the second step was 20 mm, and the screen diameter of the crusher in the third step was 4 mm. there were. The biggest cause of fiberization under these conditions is that between the fibers and vascular bundles containing more than 60% of the moisture of the bamboo material in order to cause the final pulverizer to peel the fibers without cutting them by frictional heat. It is presumed that it is important that the vascular bundle is elastic and flexible due to the weakly bonded state and the high water content.

  The produced fiber material is the largest with about 60% of vascular bundles having a length of 10-30 mm and an average diameter of 0.5 mm, and then a length of 5-10 mm formed by rupturing the vascular bundle. Thus, fibers with an average diameter of 0.05 mm were produced at a rate of approximately 10%, and powdered and crushed endothelium (nods) at a rate of approximately 30%.

  The moisture of the final crushed material is about 29% for bamboo with the best initial moisture of 62%, about 25% for bamboo with an initial moisture of 50%, and about 18% for bamboo with an initial moisture of 38%. Met.

A flat bamboo sheet (1) was formed using the fiber material obtained by defibrating the raw bamboo. Using a stainless steel plate (30 cm x 30 cm, 20 cm x 20 cm, 15 cm x 15 cm: thickness is 3 mm for both), adjusted to a basis weight of around 620 g / cm ² and having three types of areas between the heat plates of the heat compressor A thin mat with evenly dispersed fibers is formed and hot pressed. In practice, the molded sheet is easily peeled off with an aluminum foil between the stainless steel bamboo mat. Next, it is sandwiched between preheated upper and lower press plates and pressed at a predetermined pressure to raise the temperature to a predetermined temperature. Then, the switch is turned off and the electric fan cools to the predetermined temperature.

  The raw materials were adjusted by adding additives to the bamboo fiber to enhance the bond and improve the finish. The contents and notation of the mixing are summarized in Table 2. The mixing ratio is indicated by mass% (unconditioned humidity).

ウレタン微粉末は日本ウレタン工業（株）のパールセンＵ−１００（商品名）、澱粉は片栗粉、ＰＶＡ微粉末はクラレ（株）の一般グレードを用いた。

The urethane fine powder used was Pearlsen U-100 (trade name) manufactured by Nippon Urethane Industry Co., Ltd., the starch was potato starch, and the PVA fine powder was a general grade of Kuraray Co., Ltd.

Heating was performed using a test heat press (Imoto Seisakusho, maximum press: 200 kgf / 40 cm × 30 cm). Various molded samples were prepared using the raw material, heating temperature, and pressing pressure as parameters.
The test results are summarized in the table below. When hot pressing bamboo fiber (moisture: 29.4%), the temperature is raised from around 90 ° C., and after reaching a predetermined temperature, it is gradually cooled by an electric fan, and when the temperature falls below 100 ° C., the press is opened. Only the maximum temperature of the upper and lower panels is shown in Table 3 as the heating conditions.

［比較例１−４］
熱プレス面は高水分の原料を使用するため、１００℃付近を通過する熱プレスの際に水蒸気がプレス盤の間から噴出し、所定の温度に達したときには水蒸気は消失している。この高圧蒸気の発生に伴って竹繊維物のセルロース、リグニンは軟化し、プレスによって繊維物は平板化する（成形後の竹シート表面の繊維物は潰れている。）。従って、加熱の最終段階においては設定値まで上げたプレスゲージ値は竹繊維物の平板化により幾分低下する。竹繊維物のプレス盤との接触面は熱により焦げによる褐変が生じ易い。

[Comparative Example 1-4]
Since the hot press surface uses a high-moisture raw material, water vapor is ejected from between the press plates during hot pressing that passes around 100 ° C., and the water vapor disappears when a predetermined temperature is reached. As the high-pressure steam is generated, the cellulose and lignin in the bamboo fiber are softened, and the fiber is flattened by pressing (the fiber on the surface of the bamboo sheet after molding is crushed). Therefore, in the final stage of heating, the press gauge value raised to the set value is somewhat lowered by flattening the bamboo fiber material. The contact surface of the bamboo fiber material with the press board tends to brown due to scorching due to heat.

  Common paper is wet papermaking and obtains paper strength through hydrogen bonding and mechanical entanglement, but bamboo fiber is a thermoplastic synthetic resin because the fiber is rigid and the hydrogen bonding force is not exhibited in hot press. Urethane fine particles rich in flexibility were added as a binding aid. This urethane contains about twice as much as wood (20% or more), and functions as an auxiliary material for saccharides that can contribute to the fixation of fibers by being treated at high temperature and high pressure without elution. Comparative Examples 1 to 4 in which sheet forming is performed using a conventional hot press technique is formed using a raw material in which only general urethane fine particles are added and mixed.

The sample of Comparative Example 1 was not good in appearance due to the occurrence of scorching, but the smoothness and tensile strength were good. If the temperature is lowered to the point where the scorch is eliminated, the hot press effect is lowered and the finished state is deteriorated. In particular, there is a situation where scorching tends to occur on the upper board side, and when the temperature of the upper and lower boards is almost the same, there is no scorching on the lower board side, but scorching occurs on the upper board side (the smell of burnt grains) ). That is, in order to keep both surfaces of the bamboo sheet (1) on a good surface, it is necessary to select a relatively high temperature by lowering the temperature of the upper surface from the lower surface. When the heating temperature is lowered to such an extent as to suppress this browning, the adhesion state between the fibrous materials deteriorates, and the adhesive effect between the saccharide and the urethane fine particles cannot be obtained sufficiently, and the flexibility as a sheet cannot be obtained (Comparative Example 4). . Even when the upper board is lowered to 118 ° C. and the lower board is lowered to 132 ° C., the upper and lower surfaces of the molded sheet are partially burnt (Comparative Example 3).
[Comparative Example 1-3]
To improve both the heat press effect and the finished appearance, when the moisture contained in the raw material is dissipated, the sugar moves to the heating plate (the phenomenon that the upper side of the sheet becomes more scorched by heating than the lower side). In order to reduce (estimation from being), saccharides should be retained in the sheet, and starch (starch flour) which is similar to saccharides was added. Initially, the same weight percent of urethane was added to adjust the temperature of the upper and lower panels, and repeated tests to suppress poor appearance. The raw material was prepared by mixing 100 parts of bamboo fiber, 4 parts of urethane fine particles and 4 parts of starch. As a result, the burning phenomenon when only urethane was added was eliminated, but the bamboo sheet (1) was slightly swollen near the end of the bamboo sheet (1) even though the press panel was opened after the temperature was lowered to 95 ° C or lower. A stain with a width of 3 or 4 mm was generated around the swelling.

In the area surrounded by the stain, the fibers are extremely weakly adhered to each other and do not have strength. Even if the temperature was adjusted downward and the upper board temperature was 114 ° C. and the lower board temperature was 132 ° C., the swelling of the upper surface was not eliminated. (Examples 1 to 3) In order to confirm the cause of this stain and swelling (bonding failure), only starch was added (Comparative Example 5). As a result, it was found that the same stain and swelling (bonding failure) occurred and excessive starch was involved in this (the finished sheet was brittle because there was no mixing of urethane).
[Comparative Example 4-5]
Next, the effect of suppressing swelling by adding a small amount of starch to be added was tested. In Example 4, when the amount of starch was reduced to half of the amount of urethane and hot pressing was performed under the same heating conditions, the previous blistering was eliminated, and the charring was also significantly improved and eliminated except for a part. In order to prevent this partial burning, the temperature was lowered somewhat, and a good appearance could be obtained. In this condition, the press is 0.5 kgf / cm ² , the upper board temperature is 110 ° C., and the lower board temperature is 130 ° C. (Example 5)
[Example 6]
When the amount of starch was further reduced to 100 parts of bamboo fiber material, 1 part of starch resulted in thin burns on the upper and lower surfaces of the molded sheet. From this, it was found that the starch that suppresses the influence of moisture in the bamboo fiber material in the heat press is about 2 starch compared to the bamboo fiber material 100. Additives that improve the appearance of the bamboo sheet (1) after molding include, in addition to starch, water-absorbing substances such as water glass dry powder, gelatin fine powder, cellulose fine powder, and defibrated fibers of waste office paper Can be used.

Moisture contained excessively in bamboo (a high moisture state like raw bamboo is desirable for sufficient defibration of bamboo) to obtain thermoplasticity and increase the bonding strength between fiber materials It is indispensable. However, this excess moisture interferes with surface formation when pressing at high temperatures in conjunction with sugars. After defibration, it can be adjusted to moisture suitable for hot pressing by microwave heating or the like, but it is a difficult process when economic efficiency and uniformity are obtained. Therefore, it is necessary to suppress the influence of the saccharide acting on the minus while keeping the moisture at the time of defibration. The effect of adding starch, which is an analog of hygroscopic bamboo saccharides, was confirmed.
[Comparative Example 9-10]
Further, there is a fine powder of polyvinyl alcohol (PVA) as an analog of the same type of hygroscopic saccharide. This additive has a property of dissolving in warm water, and when used as fine particles, it exhibits hygroscopicity like starch. Moreover, it has thermoplasticity like urethane. That is, it can be said that it is a substance having both the functions of urethane fine powder and starch. As a result of testing by changing the amount of PVA added, it was found that if the PVA is about 10, a bamboo sheet with good bonding strength between the fibers and rich in flexibility can be formed with respect to the bamboo fiber object 100. Instead of PVA, a dry powder of a water-dispersible resin processed product such as vinyl acetate emulsion, SBR, or acrylic latex can be used.
[Comparative Example 7-8]
Next, the press pressure was examined in order to enhance the bond between the fibers (vascular bundles) during the thermoforming of the bamboo sheet (1). The standard pressure was set to 0.5 kgf / cm ^{2 because} of the ability of the hot press machine in the test, but when the mold was lowered to 0.3 kgf / cm ² , the fiber was crushed lightly, and the smoothness of the sheet The gloss is poor and the strength is significantly reduced. On the contrary, it was found that when the pressure was increased to 0.9 kgf / cm ² , the crushing of the fiber increased by the press, the smoothness of the sheet surface was improved, and the gloss was increased. Although the test could not be performed at a pressure exceeding 0.9 kgf / cm ² due to the limitations of the testing machine, it can be assumed that if a pressure exceeding this is applied under heating, a sheet having more excellent strength characteristics can be formed. In order to improve the appearance of the bamboo sheet, it is appropriate to set conditions for suppressing the heating temperature and increasing the press pressure.

If the basis weight is about 620 g / m ² as the flat sheet shown in the examples, the thickness is less than 1 mm and it can be used as a paperboard for bamboo dry press molding. Further, the shape to be molded can be any shape such as a dish shape using male and female molds or a lid-type container formed with a hinge portion. A bamboo sheet having a predetermined dimension can be manufactured by using a batch type pressing device (the structural drawing is omitted). Moreover, a continuous bamboo sheet (bamboo pressure paper) can be manufactured with a continuous belt type device (structural drawing is omitted).

  It can also be finished in a plywood shape with a thickness of about 5-20 mm. If the appearance defect such as scorch is ignored, the strength as a material is improved by pressing both sides at about 150 ° C.

  According to the present invention, a practical dry molding method is established by providing a method of making a product by utilizing the feature that there is a lot of saccharides as much as there is less lignin, which is a characteristic of bamboo only, using bamboo, and It has industrial applicability in terms of contributing.

It is explanatory drawing which shows the various components of the bamboo defibrated material used for this invention, (A) is a vascular bundle, (B) is a fiber and cotton-like material, (C) is a nod (undefibrated material, soft material). Tissue fragment). It is a surface enlarged view of the bamboo sheet | seat used for this invention.

Explanation of symbols

1 Bamboo sheet

Claims (4)

  Unsorted bamboo raw material that uses bamboo defibrated material that has a moisture content of about 25% or more obtained through the refining treatment process, or non-defibrated material that is an impurity from the defibrated material and pulverized A dry forming method for bamboo fiber, wherein a forming raw material obtained by adding a thermoplastic resin and a hygroscopic material to a selected bamboo raw material from which fine fibers have been removed is mixed and formed into an arbitrary shape by hot pressing.   A hygroscopic thermoplastic resin is applied to the unsorted bamboo raw material that uses the defibrated material of the bamboo that has passed through the defibrating process as it is, or to the selected bamboo raw material from which the defibrated material and non-defibrated material that have been pulverized are removed A dry forming method for bamboo fiber, wherein the forming raw material added and mixed is formed into an arbitrary shape by hot pressing. 3. The method for dry-molding bamboo fiber according to claim 1, wherein the forming raw material is heated at a temperature of 140 ° C. or lower and 100 ° C. or higher and pressed at a pressure of 0.5 kgf / cm ² or higher. .   4. The bamboo according to claim 3, wherein the forming raw material is heated at a lower heating plate at a temperature of 140 ° C. or lower and 110 ° C. or higher, and the upper heating plate is heated at a temperature of 130 ° C. or lower and 100 ° C. or higher. A dry molding method for textiles.

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