Preparation method of natural color bamboo fiber fluff pulp

Abstract

The invention discloses a preparation method of natural-color bamboo fiber fluff pulp. The preparation method comprises the steps of cold alkali treatment of bamboo chips, extrusion, pulp grinding, screening and pulp board papermaking. Cold alkali is adopted for treating bamboo wood, hemicelluloses and parenchyma cells influencing the water absorption capacity of the bamboo wood are removed, pulp obtained after cold alkali treatment is subjected to extrusion treatment, then natural-color bamboo pulp is obtained through mechanical pulp grinding and screening, and the bamboo pulp is squeezed and subjected to flat plate drying treatment to obtain the bamboo fluff pulp board. According to the invention, the bamboo fluff pulp has better raising and liquid absorption performance and higher pulping yield.

Description

Technical Field

[0001] The invention relates to the technical field of pulping and papermaking, and in particular to a method for preparing natural color bamboo fiber fluff pulp. Background Art

[0002] my country is one of the countries with the richest bamboo forest resources in the world. According to relevant statistics, the bamboo forest area in my country in 2020 is nearly 6.5 million hectares. Compared with wood, bamboo is more renewable and more environmentally friendly. Bamboo with a short rotation cycle and high economic value is the best substitute to solve the gap between wood supply and demand. Fluff pulp is an absorbent core pulp used in personal care products (such as disposable diapers, adult incontinence products, female hygiene / care products, absorbent towels, etc.). At present, the fluff pulp on the market is mainly wood pulp fiber products. The import volume of domestic fluff pulp reaches 800,000-1 million tons / year, and the annual growth rate is about 3%-4%. The shortage of pulping raw materials has seriously restricted the development of my country's fluff pulp industry. Bamboo has a high fiber content (usually 40%-60%) and a hemicellulose content of about 20%, which is basically the same as coniferous and broad-leaved wood. The fiber aspect ratio and wall cavity ratio are large, and the thick-walled fiber has strong compression resistance, which can give the pulp board a better fluffy structure. It can be used to replace wood pulp fiber fluff pulp and promote high value-added applications in the bamboo fiber industry.

[0003] There are two disadvantages in using bamboo fiber in the preparation of fluff pulp. First, the more miscells in bamboo fiber will fill the pores between fibers, thereby blocking the capillaries and promoting the bonding between fibers. Second, the hydroxyl groups in the hemicellulose molecules of bamboo fiber are bonded to each other. These two factors make it difficult for bamboo fluff pulp to build a fluffy structure and raise the nap. Currently, most bamboo fluff pulp is bleached pulp, and the bleaching process mostly uses chlorine bleaching, which increases the input, increases the pulping wastewater, and reduces the pulping yield. In addition, some wood pulp and fiber debonding agents are usually added to reduce the bonding between fibers, which increases the manufacturing process and cost. Summary of the invention

[0004] Based on this, the present invention provides a method for preparing natural color bamboo fiber fluff pulp, which uses bamboo raw materials to prepare high-yield natural color fluff pulp, removes hemicellulose through cold alkali treatment, reduces fiber loss and softens lignin, thereby reducing subsequent pulping energy consumption. The obtained natural color bamboo fiber fluff pulp has effectively improved water absorption and water absorption rate, and can be used for high-end sanitary product materials.

[0005] To achieve the above object, the present invention provides the following technical solutions: A method for preparing natural bamboo fiber fluff pulp, characterized by comprising the following steps: (1) Cold alkali treatment of bamboo strips: soak the bamboo strips in a 5% NaOH solution at a temperature of 15-40 °C for 4 h; (2) Extrusion: The slurry from step (1) is fed into a twin-screw extruder for extrusion with an extrusion diameter of 320 mm; (3) Refining: The extruded pulp is subjected to refining treatment to obtain bamboo pulp, and the number of refining stages is 2; (4) Screening: Screening the bamboo pulp using a 0.15 mm slotted screen; (5) Pulp board production: The bamboo pulp obtained in step (4) is squeezed and dried on a flat plate at 105°C to produce a bamboo fluff pulp board.

[0006] Preferably, in step (1), the solid-to-liquid ratio of the bamboo chips to the NaOH solution is 1:5.

[0007] Preferably, in the step (2), the extrusion is performed twice.

[0008] Preferably, in step (3), the clearances between the grinding discs used for refining are 5.0 mm, 2.0 mm, 1.0 mm, 0.5 mm and 0.1 mm, respectively.

[0009] Preferably, the bamboo pieces are bamboo of the Chinese wolfberry variety.

[0010] Based on the above technical solution, the embodiments of the present invention can at least produce the following technical effects: The present invention provides a method for preparing natural bamboo fiber fluff pulp. Compared with bleached chemical bamboo fluff pulp, the present invention does not use bleaching chemicals such as chlorine, thereby reducing environmental pollution and equipment investment. Cold alkali mild treatment of bamboo materials can remove hemicellulose and foreign cells, effectively improve the water absorption and liquid absorption rate of bamboo fibers, while reducing fiber loss and softening lignin, improving pulping yield, reducing subsequent grinding energy consumption, and achieving the purpose of reducing costs. High-yield natural bamboo fiber fluff pulp is prepared using bamboo raw materials. Cold alkali treatment removes hemicellulose while reducing fiber loss and softening lignin, so that subsequent grinding energy consumption is reduced. The obtained natural bamboo fiber fluff pulp has effectively improved water absorption and water absorption rate, and can be used for high-end sanitary product materials. DETAILED DESCRIPTION

[0011] The present invention will be further described below in conjunction with examples, which are intended to illustrate the present invention rather than to limit the scope of the present invention. Those skilled in the art can determine the essential features of the present invention, and can make various modifications and changes to the present invention without departing from the spirit and scope of the present invention to enable it to use various purposes and conditions.

[0012] The present invention provides a method for preparing natural bamboo fiber fluff pulp, comprising: (1) Cold alkali treatment of bamboo strips: Bamboo strips with a length of 18-55 mm and a width of 10-20 mm were immersed in a 5% NaOH solution with a solid-liquid ratio of 1:5 at a temperature of 15-40 °C for 4 h to remove most of the hemicellulose and miscellaneous cells in the bamboo. (2) Extrusion: The slurry from step (1) is fed into a twin-screw extruder for extrusion, with an extrusion diameter of 320 mm and a number of extrusions of 2 times; (3) Refining: The extruded pulp is subjected to refining treatment to obtain bamboo pulp. The number of refining stages is 2, and the gaps between the grinding discs are 5.0 mm, 2.0 mm, 1.0 mm, 0.5 mm, and 0.1 mm, respectively. (4) Screening: Screening the bamboo pulp with a 0.15 mm slotted screen to remove short fibers, impurities and miscellaneous cells; (5) Pulp board production: The bamboo pulp obtained in step (4) is squeezed and dried on a flat plate at 105° C. to produce a bamboo fluff pulp board. Example 1

[0013] 500 tons of bamboo chips were immersed in 2500 tons of 5% NaOH solution at 40℃ and stirred for 4 hours to remove hemicellulose and miscellaneous cells in the bamboo and soften the lignin in the bamboo fiber. The obtained slurry was sent to a twin-screw extruder for two extrusions, and the extruder diameter was adjusted to 320 mm; The extruded slurry was refined in two stages using a refiner, with the gaps between the grinding discs being 5.0 mm, 2.0 mm, 1.0 mm, 0.5 mm, and 0.1 mm, respectively; The pulp after refining is screened with a 0.15 mm slotted screen to remove short fibers, miscellaneous cells and impurities; The screened pulp is pressed and dried on a flat plate at 105°C to obtain a bamboo fluff pulp board. Example 2

[0014] One ton of bamboo slices of the Chinese bamboo were immersed in 5 tons of 5% NaOH solution, the temperature was adjusted to 15 °C, and the mixture was stirred for 4 h to remove hemicellulose and foreign cells in the bamboo material and soften the lignin in the bamboo fiber. The obtained slurry was sent to a twin-screw extruder for two extrusions, and the extruder diameter was adjusted to 320 mm; The extruded slurry was refined in two stages using a refiner, with the gaps between the grinding discs being 5.0 mm, 2.0 mm, 1.0 mm, 0.5 mm, and 0.1 mm, respectively; The pulp after refining is screened with a 0.15 mm slotted screen to remove short fibers, miscellaneous cells and impurities; The screened pulp is pressed and dried on a flat plate at 105°C to obtain a bamboo fluff pulp board. Example 3

[0015] 10 tons of bamboo pieces of Bamboo stalks were immersed in 50 tons of 5% NaOH solution at 25℃ and stirred for 4 hours to remove hemicellulose and miscellaneous cells in the bamboo and soften the lignin of bamboo fiber. The obtained slurry was sent to a twin-screw extruder for two extrusions, and the extruder diameter was adjusted to 320 mm; The extruded slurry was refined in two stages using a refiner, with the gaps between the grinding discs being 5.0 mm, 2.0 mm, 1.0 mm, 0.5 mm, and 0.1 mm, respectively; The pulp after refining is screened with a 0.15 mm slotted screen to remove short fibers, miscellaneous cells and impurities; The screened pulp is pressed and dried on a flat plate at 105°C to obtain a bamboo fluff pulp board.

[0016] Cold alkali mild treatment of bamboo can remove hemicellulose and foreign cells, effectively improve the water absorption and liquid absorption speed of bamboo fiber, reduce fiber loss and soften lignin, increase pulping yield, reduce subsequent pulping energy consumption, and achieve the purpose of reducing costs. High-yield natural fluff pulp is prepared from bamboo raw materials. Cold alkali treatment removes hemicellulose, reduces fiber loss and softens lignin, and reduces subsequent pulping energy consumption. The obtained natural bamboo fiber fluff pulp can be used as a material for high-end sanitary products.

[0017] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for preparing natural bamboo fiber fluff pulp, characterized in that: The following steps are involved: (1) Cold alkali treatment of bamboo strips: soak the bamboo strips in a 5% NaOH solution at a temperature of 15-40 °C for 4 h; (2) Extrusion: The slurry from step (1) is fed into a twin-screw extruder for extrusion with an extrusion diameter of 320 mm; (3) Refining: The extruded pulp is subjected to a refining treatment to obtain bamboo pulp, and the number of refining stages is 2; (4) Screening: Screening the bamboo pulp using a 0.15 mm slotted screen; (5) Pulp board production: The bamboo pulp obtained in step (4) is squeezed and dried on a flat plate at 105°C to produce a bamboo fluff pulp board.

2. The method for preparing natural bamboo fiber fluff pulp according to claim 1, characterized in that: In the step (1), the solid-to-liquid ratio of the bamboo chips to the NaOH solution is 1:

5.

3. The method for preparing natural bamboo fiber fluff pulp according to claim 1, characterized in that: In the step (2), the extrusion is performed twice.

4. The method for preparing natural bamboo fiber fluff pulp according to claim 1, characterized in that: In the step (3), the grinding disc gaps used for the refining are 5.0 mm, 2.0 mm, 1.0 mm, 0.5 mm, and 0.1 mm, respectively.

5. The method for preparing natural bamboo fiber fluff pulp according to claim 1, characterized in that: The bamboo pieces are Phyllostachys chinensis.