Method for manufacturing bamboo fiber

Abstract

To provide a bamboo fiber having a maximum line width of ≤ 200 μm and a length of ≥ 5 μm without using water retting, chemical retting using caustic soda or the like, or heated steam.SOLUTION: The medium 20mm fiber having an average fiber length of ≤ 150 μm and a length of ≥ Hosodake can be obtained by using a Wakatake of 2 weeks to 9 months old of a bamboo, longitudinally cutting the juice to make a strip, subjecting the strip to (1) a roughly opening process by roller crushing, (2) a roughly opening process using a pin cylinder and (3) a medium finely opening process using a carding machine equipped with a coarse metallic wire. The fine Hosodake fibers having ≤ 80 μm average fiber widths and ≥ 10mm lengths can be provided by treating (3) the medium-bamboo fibers with (4) a carding machine equipped with a fine metallic wire.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a natural plant fiber used in nonwoven fabrics with thermoplastic resin binder fibers and in blended yarns with cotton, and more particularly to a method for producing bamboo fiber that can be used in nonwoven fabrics and blended yarns with cotton. [Background technology]

[0002] Generally, when manufacturing nonwoven fabrics using thermoplastic resins as binder fibers and natural plant fibers as reinforcing materials, hemp-based short fibers such as kenaf and jute are used (Non-Patent Document 1). In addition, for spun yarns, seed hair fibers such as cotton, bast fibers obtained from hemp such as flax, and leaf vein fibers obtained from bananas, sisal, pineapples, etc. are used (Non-Patent Document 2).

[0003] In the case of nonwoven fabrics made from kenaf fiber, the average fiber width (maximum width in both the vertical and horizontal directions) is 50 μm to 100 μm, and the fiber length is 30 mm to 60 mm. To make spun yarn, thin and long fibers are required. For example, in the case of ramie, the average fiber width is 60 μm, and the length is 60 mm to 200 mm. In the case of sisal fiber, the average fiber width is thick, at 100 μm to 200 μm, but the fiber length can reach 50 cm.

[0004] When extracting fibers from kenaf, jute, or flax, bio-retching is performed by pre-harvesting the stalks and soaking them in a river for a certain period of time. When extracting bamboo fibers other than bast fibers, the vascular bundle sheath (see Figure 1) that forms the bamboo fiber is strongly bonded to the surrounding parenchyma cell walls, so retching is required using a caustic soda (NaOH) solution with a concentration of 1% or higher (Non-Patent Document 3). In this case, if the strongly alkaline wastewater containing dissolved lignin is not properly treated, it will cause environmental pollution. However, treating the strongly alkaline wastewater, also known as black liquor, requires acid for neutralization, a large amount of water, and energy, so the use of natural plant fibers does not necessarily contribute to carbon neutrality.

[0005] One method for extracting bamboo fiber is the explosion method (Non-patent document (3)), but this method requires a lot of energy to produce superheated steam, and the superheated steam decomposes lignin, causing the extracted bamboo fiber to have an odor.

[0006] Furthermore, kenaf, jute, flax, ramie, sisal, banana, pineapple, etc. are not cultivated in Japan for the purpose of fiber extraction, and most of the fibers obtained from these are imported. Therefore, it is desirable to produce bamboo fiber using raw materials that do not rely on imports and that are environmentally friendly. [Prior art documents] [Non-patent literature]

[0007] [Non-Patent Document 1] N. Ramli1, N. Mazlan, Y. Ando, ​​Z. Leman, K. Abdan, AA. Aziz, NA. Sairy, “Natural fiber for green technology in automotive industry: A brief review”, DOI:10.1088 / 1757-899X / 368 / 1 / 012012(2018) [Non-patent document 2] http: / / kan5.sakura.ne.jp / konwa / KuramaeHandout / kohyama.pdf [Non-patent document 3] Toru Fujii, Kazuya Okubo, "Development and Application of Bamboo Fiber Reinforced Composite Materials," Research Journal of the Japan Agriculture, Forestry and Fisheries Technology Promotion Association, Vol. 28, No. 10 (2005) Summary of the Invention [Problem to be solved by the invention]

[0008] Therefore, the present invention has been made with a focus on the above-mentioned problems, and aims to provide a method for producing thin and long bamboo fibers that can be used to produce nonwoven fabrics and spun yarns using bamboo, which is abundant in Japan, without using any chemicals such as bio-retching, explosion, or caustic soda. [Means for solving the problem]

[0009] That is, in order to solve the above-mentioned problems, the present invention uses young bamboo that is not yet lignified and is between 2 weeks and less than 9 months old, preferably between 3 weeks and less than 5 weeks old.

[0010] Young bamboo is cut and split lengthwise into 2 to 12 equal pieces to obtain bamboo strips.

[0011] If it is not possible to immediately extract fiber from the cut young bamboo, store the cut young bamboo under running water.

[0012] The bamboo strips are crushed by two rotating rollers to roughly defibrate them. The crushing force applied to the rollers is 500N to 5000N per strip. This causes the bamboo strips to spread horizontally, separating the fibers from the parenchyma cells. The crushing force is adjusted within the range of 500N to 5000N depending on the age of the bamboo, the thickness and width of the strip. If the crushing force is too strong, the fibers will be cut in the middle, and long coarse fibers will not be obtained.

[0013] The bamboo strips that have been roughly defibrated by roller crushing are cut into pieces of 50mm to 200mm and then roughly defibrated using a rotating pin cylinder with sawtooth or nail-shaped pins attached to the surface of a cylindrical drum.

[0014] The coarsely defibrated bamboo short fibers are then defibrated in a carding machine or a depilator with equivalent functionality to obtain thin, long fibers. The medium-fine fiber obtained in the first carding process is defibrated using coarse metallic wires with a height of 5 mm or more. This produces medium-fine fibers with an average fiber width of 150 μm or less. These medium-fine fibers are used to manufacture nonwoven fabrics.

[0015] Bamboo fibers that can be used in blended yarns with cotton must be fine fibers with an average fiber width of 80 μm or less. They are produced by opening up fine bamboo fibers in a carding machine or a depilator equipped with metallic wires of 3 mm or less in height and 0.8 mm or less in width. [Brief explanation of the drawings]

[0016] [Figure 1] Cross section of bamboo fiber, showing the vascular bundle sheath [Figure 2] Diagram showing the manufacturing process of bamboo fine fiber [Figure 3] Roller crushing process and the resulting bamboo fiber [Figure 4] Pin cylinder coarse fiber defibration process and the resulting bamboo coarse fiber [Figure 5] Fiber defibration process using a carding machine, and the resulting medium-fine bamboo fiber and fine bamboo fiber slivers blended with cotton DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0018] In this embodiment, medium-fine and fine bamboo fibers are produced using madake bamboo that is 3.5 weeks old. The day when the bamboo shoots emerge from the ground at a length of less than 10 cm is considered the birthday. At this time, the sides of the shoots are painted red to record the bamboo's birthday. 25 days after birth, the madake bamboo is cut down from the base. The diameter of the cut bamboo at the base is 9 cm.

[0019] The process shown in Figure 2 can be used to produce medium-fine bamboo fibers for nonwoven fabrics and fine bamboo fibers for blended yarns with cotton.

[0020] First, the branches and leaves of the cut bamboo were removed and cut into lengths of 2m. Then, using a two-handed bamboo splitter, the bamboo was split into four equal pieces, yielding bamboo strips 2.5cm wide and 2m long. If the bamboo was thick, it was split into six or eight pieces, each 2cm to 3cm wide.

[0021] The strips were passed through a roller crusher with a roller diameter of 10 cm, and the strips were spread laterally to obtain the bamboo rough fiber shown in Figure 3. A spring applied a crushing force of 1000 N to the upper roller.

[0022] The crude fibers are held together by parenchyma cells and are not separated into individual strands. Next, these crude fibers are cut into lengths of 100 mm and then roughly defibrated using a pin cylinder with sharp, nail-like pins attached to a drum. This results in crude fibers with several fibers still stuck together, as shown in Figure 4.

[0023] Next, the fibers were defibrated in a carding machine equipped with a coarse metallic wire to obtain medium-fine fibers for nonwoven fabric, as shown in Figure 5. The minimum fiber width was 65 μm, the maximum fiber width was 190 μm, the average fiber width was 135 μm, the minimum length was 20 mm, the maximum length was 83 mm, and the average fiber length was 53 mm. The metallic wire used for the dofer was DU34IH (manufactured by Kanai Juyo Kogyo).

[0024] To blend with cotton to produce spun yarn, the medium-fine fibers needed to contain less than 10% bamboo fiber and could only produce extremely thick blended yarn with a cotton count of 10 or less. Therefore, the medium-fine fibers were then defibrated using a carding machine equipped with an ultra-fine metallic wire (CC96XXFF: manufactured by Kanai Juyo Kogyo Co., Ltd.) attached to the cylinder. This resulted in fine fibers suitable for thin blended yarn with a bamboo fiber content of 30% or more and a cotton count of 20 or more.

[0025] The fine bamboo fibers are shown in Figure 5. The minimum fiber width was 35 μm, the maximum fiber width was 78 μm, the average fiber width was 71 μm, the minimum length was 10 mm, the maximum length was 48 mm, and the average fiber length was 32 mm.

Claims

1. Medium-fine bamboo fibers with an average fiber width of 150 μm or less and a length of 20 mm or more are extracted by mechanical processing only from the vascular bundles of young bamboo that is between two weeks and nine months old.

2. Fine bamboo fibers with an average fiber width of 80 μm or less and a length of 10 mm or more are extracted from the vascular bundles of young bamboo that is between two weeks and nine months old by mechanical processing alone.

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