Classification method for industrially extracting natural bamboo fibers from solid bamboo wastes

Abstract

The invention discloses a grading method for industrially extracting natural bamboo fibers from solid bamboo wastes, which comprises the following steps of: grading the bamboo wastes into sheets, blocks and scraps through mechanical screening, cleaning, soaking in alkali liquor and heating and softening by microwaves, and respectively carrying out physical and chemical treatment, independent physical treatment or physical and biological treatment according to different forms. Filamentous, fluffy and powdery natural bamboo fibers are obtained. The method is free of steam, low in energy consumption and low in cost, the total proportion of the natural bamboo fibers is larger than or equal to 60%, the method can meet the requirements of multiple industries such as automobile interiors, composite materials and bioplastics, bamboo waste is efficiently utilized, the method is suitable for industrial production, and improvement of the economical efficiency and sustainable development of the bamboo industry is facilitated.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of bamboo waste grading, in particular to a grading method for extracting natural bamboo fibers from solid bamboo waste in industrialization. BACKGROUND

[0002] Bamboo is a plant resource with great advantages in China, and its species, area, volume and yield are all the largest in the world. However, 60%-70% of waste, including bamboo chips, bamboo blocks, bamboo shavings and other sheet-shaped, block-shaped and shaving-shaped processing residues, is generated during the processing and utilization of bamboo. These wastes have long lacked efficient and refined utilization methods: most of them are discarded, buried or burned at will, not only causing great waste of bamboo resources, but also easily causing environmental pollution; even if some of them are utilized, it is difficult to realize their potential value.

[0003] At the same time, bamboo fiber, as a natural and environmentally friendly green fiber, is widely used in furniture, building materials, textiles, automotive interiors and other fields, but the traditional bamboo fiber extraction technology has significant limitations: on the one hand, traditional methods mostly rely on intact bamboo, making it difficult to utilize the above-mentioned bamboo waste with different shapes; on the other hand, the process is complex, requiring high-temperature cooking, multiple fiber opening steps and relying on steam medium, resulting in high energy consumption, high cost, low efficiency and inability to meet the needs of industrial production.

[0004] In addition, the existing technology lacks targeted grading means for bamboo waste, and cannot process it in a refined manner according to the morphological differences (sheet-shaped, block-shaped, shaving-shaped) of bamboo waste, making it difficult to obtain diversified bamboo fiber products that meet the needs of different industries, further limiting the comprehensive utilization rate of bamboo resources and the economic benefits of the bamboo industry. SUMMARY

[0005] This section is intended to summarize some aspects of the embodiments of the present application and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the abstract and title of the specification to avoid obscuring the purpose of this section, abstract and title, and such simplifications or omissions cannot be used to limit the scope of the present application.

[0006] Therefore, the purpose of the present application is to provide a grading method for extracting natural bamboo fibers from solid bamboo waste in industrialization, which processes bamboo waste by means of "mechanical screening-physical + chemical / biological combination", overcoming the problem of high energy consumption, high cost and low efficiency caused by the use of steam medium in traditional bamboo fiber extraction methods.

[0007] To solve the above technical problems, according to one aspect of the present application, the present application provides the following technical scheme: A grading method for industrial extraction of natural bamboo fibers from solid bamboo waste, the steps are as follows: S1, mechanical screening grading of solid bamboo waste, obtaining at least one form of bamboo waste in the form of sheet, block and scrap; S2, the graded bamboo waste is sequentially washed, soaked in alkali and softened by microwave heating treatment; S3, different forms of bamboo waste are processed by physical treatment combined with chemical treatment, physical treatment alone or physical treatment combined with biological treatment, to obtain natural bamboo fibers of different forms and sizes.

[0008] As a preferred scheme of the grading method for industrial extraction of natural bamboo fibers from solid bamboo waste, wherein the mechanical screening grading is realized by a vibrating screen, and sheet-shaped, block-shaped and scrap-shaped bamboo waste is screened out from top to bottom according to size difference.

[0009] As a preferred scheme of the grading method for industrial extraction of natural bamboo fibers from solid bamboo waste, wherein the alkali soaking conditions are as follows: the bamboo waste is soaked in a mixed alkali solution containing NaOH, Na2SO3 and JFC penetrant for 24h at room temperature; Wherein, the concentration of NaOH is 50g / L, the concentration of JFC penetrant is 3g / L, and the amount of Na2SO3 added is 2% of the dry mass of the bamboo waste.

[0010] As a preferred scheme of the grading method for industrial extraction of natural bamboo fibers from solid bamboo waste, wherein the parameters of the microwave heating softening treatment are as follows: microwave power 400W, treatment time 4-6min.

[0011] As a preferred scheme of the grading method for industrial extraction of natural bamboo fibers from solid bamboo waste, wherein the physical treatment combined with chemical treatment is used for sheet-shaped bamboo waste, which specifically includes: Physical treatment: sequentially perform pressure cracking treatment and disc grinding treatment, the pressure cracking treatment is hot pressing under the condition of 150℃ and 0.2MPa, with a breathing interval of 5min, and the disc grinding treatment uses a three-disc single-rotor disc grinder; Chemical treatment: mix the product after physical treatment with an alkaline solution at a mass ratio of 1:10-20, react in a 30-40℃ water bath for 60-90min, and obtain silk-like bamboo raw fibers after freeze-drying and vacuum drying.

[0012] As a preferred scheme of the grading method for industrial extraction of natural bamboo fibers from solid bamboo waste, wherein the physical treatment alone is used for block-shaped bamboo waste, which specifically includes: Cutting treatment: the block-shaped bamboo waste is cut into granular particles with a length of 5-10 mm and a width of 3-6 mm by a knife roll bamboo cutting machine; Carding treatment: the granular bamboo waste is crushed to form fibrous and powdery materials; Dehydration treatment: cellulose and non-cellulose components are separated by high-speed stirring and shearing force to obtain fluff-like raw bamboo fibers.

[0013] As a preferred scheme of the grading method for extracting natural bamboo fibers from solid bamboo waste in the industrialization, the physical treatment and biological treatment are combined for the scrap bamboo waste, and the physical treatment specifically includes: Physical treatment: the planetary ball mill is used to grind the material in the zirconia ball mill tank for 20 min to obtain granular or crushed material; Biological treatment: the ground material is mixed with a composite enzyme solution, and a catalyst is added for pressure treatment at 160 DEG C for 3 h; Centrifugal treatment: centrifugal treatment is performed at a speed of 3000-10000 r / min for 10-30 min, and the powder-like raw bamboo fibers are obtained after cold drying at 60-30 DEG C for 12-36 h.

[0014] As a preferred scheme of the grading method for extracting natural bamboo fibers from solid bamboo waste in the industrialization, the total proportion of the natural bamboo fibers prepared is ≥60%, and the proportion of the silk-like raw bamboo fibers is ≥70%, the proportion of the fluff-like raw bamboo fibers is ≥60%, and the proportion of the powder-like raw bamboo fibers is ≥50%.

[0015] As a preferred scheme of the grading method for extracting natural bamboo fibers from solid bamboo waste in the industrialization, the composite enzyme solution includes polygalacturonate lyase, pectin lyase, polygalacturonate hydrolase, pectin hydrolase, pectin esterase, xylanase and glucanase.

[0016] As a preferred scheme of the grading method for extracting natural bamboo fibers from solid bamboo waste in the industrialization, the solid bamboo waste includes naturally occurring flaky, blocky, scrap bamboo waste or a combination of at least two thereof.

[0017] Compared with the prior art, the present application has the beneficial effects that: 1. The present application realizes efficient utilization through targeted grading treatment process for different forms of bamboo waste such as flaky, blocky and scrap, solves the problems of low utilization rate, serious waste and environmental pollution of traditional bamboo waste, and significantly improves the comprehensive utilization value of bamboo resources.

[0018] 2. By the hierarchical processing mode of "mechanical screening-physical + chemical / biological combination", natural bamboo fibers of different forms and sizes such as filamentous, fluffy and powdery can be obtained, wherein the total proportion of bamboo raw fibers is greater than or equal to 60%, and the proportion of each form of fiber meets the application requirements of the industry (filamentous is greater than or equal to 70%, fluffy is greater than or equal to 60%, and powdery is greater than or equal to 50%), which can provide strong adaptability raw materials for downstream industries such as automobile interior panels, disposable meal boxes, green composite materials and biological plastics, and expand the application range of bamboo fibers.

[0019] 3. The present application discards the dependence on steam medium in the traditional extraction method, and uses high-efficiency processing means such as microwave heating softening, shortens the process flow, and reduces energy consumption and operation cost; at the same time, the equipment such as vibrating screen, fracturing machine and disc mill used is simple and easy to obtain, which can realize large-scale industrial production, and solve the problems of high energy consumption, high cost and low efficiency of traditional technology.

[0020] 4. By efficiently utilizing bamboo waste, the pollution to the environment caused by waste incineration, burial and other treatment methods is reduced, and the dependence on raw bamboo is also reduced, which is in line with the concept of green development and has important significance for promoting the sustainable development of bamboo industry. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the present application will be described in detail below in combination with the drawings and detailed embodiments. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor. Among them: Figure 1 The flow chart of the present application is a kind of industrialization from solid bamboo waste to extract natural bamboo fiber grading method. DETAILED DESCRIPTION

[0022] In order to make the above-mentioned purposes, features and advantages of the present application more apparent and easy to understand, the specific embodiments of the present application will be described in detail below in combination with the drawings.

[0023] The present application provides a kind of industrialization from solid bamboo waste to extract natural bamboo fiber grading method, by "mechanical screening-physical + chemical / biological combination" to bamboo waste processing, overcome the traditional bamboo raw fiber extraction mode needs to use steam medium, lead to the problem of large classification energy consumption, high cost and low efficiency.

[0024] Figure 1 The flow chart of the present application is a kind of industrialization from solid bamboo waste to extract natural bamboo fiber grading method, and the above-mentioned industrialization from solid bamboo waste to extract natural bamboo fiber grading method will be described in detail below in combination with Figure 1 and examples 1-3.

[0025] Example 1: Grading method for extracting natural bamboo fiber from sheet bamboo waste This embodiment targets sheet-like bamboo waste (2-5mm thick, 10-20mm long) and employs a "mechanical screening-physical + chemical combination method" to extract natural bamboo fiber. The specific steps are as follows: 1) Mechanical screening and cleaning: Put the sheet bamboo waste into a vibrating screen (screen mesh size 8mm), adjust the vibration frequency to 30Hz and the amplitude to 5mm, and screen from top to bottom to remove impurities to obtain pure sheet bamboo waste; rinse with clean water until the outflow is clear, and drain the water; 2) Alkaline solution soaking: Place the cleaned sheet bamboo waste in a mixed alkaline solution (composition: NaOH 50g / L, JFC permeation 3g / L, Na2SO3 added at 2% of the dry mass of bamboo waste) and soak at room temperature (25℃) for 24 hours, stirring once every 6 hours to ensure that the bamboo waste is fully soaked; 3) Microwave heating softening: Take out the soaked sheet bamboo waste, rinse it with clean water until pH=7, put it into a microwave heating softening machine, set the power to 400W, and the processing time to 5min to achieve degumming and softening and shaping. After taking it out, let it cool naturally to room temperature.

[0026] 4) Physical treatment (fracturing + disc milling): Fracturing treatment: The softened sheet bamboo waste is placed into a horizontal press, and the hot pressing temperature is set to 150℃ and the pressure to 0.2MPa. The breathing interval is 5min (that is, the pressure is released for 10s every 5min and then repressurized) to separate the vascular tissue from the parenchyma tissue in one step, so as to obtain fiber bundles or fiber fragments. Disc grinding: The fiber bundles / fragments mentioned above are fed into a three-disc single-action disc grinding machine. The disc spacing is adjusted to 0.3 mm, and the discs are ground three times to achieve secondary dissociation of vascular tissue and thin-walled tissue, resulting in preliminarily separated fibers.

[0027] 5) Chemical treatment (alkali purification): The milled fibers are mixed with an alkaline solution (NaOH concentration 30g / L) at a mass ratio of 1:15 and reacted in a 40℃ water bath for 75min to remove residual non-cellulose substances; after the reaction, the fibers are rinsed with water until pH=7, then freeze-dried at -20℃ for 36h, and then vacuum dried (60℃, 12h) to obtain filamentous bamboo fibers.

[0028] Testing revealed that the filamentous bamboo fibers obtained in this embodiment have a diameter of 125-140 μm, a length of 1-4 mm, account for 72% of the total mass of sheet bamboo waste, and have a purity of ≥90%. They can be used to produce automotive interior panels, disposable lunch boxes, etc.

[0029] Example 2: Grading method for extracting natural bamboo fiber from block bamboo waste The embodiment is directed to blocky bamboo waste (5-15 mm in length), and natural bamboo fibers are extracted by "mechanical screening-physical method", and the specific steps are as follows: 1) Mechanical screening and cleaning: put the blocky bamboo waste into a vibrating screen (screen aperture 5 mm), adjust the vibration frequency to 25 Hz and the amplitude to 4 mm, screen out the debris and impurities, and obtain pure blocky bamboo waste; rinse with clean water until the effluent is clear, and drain the water; 2) Alkali immersion: put the cleaned blocky bamboo waste into a mixed alkali solution (NaOH 50 g / L, JFC penetrant 3 g / L, and Na2SO3 2% of the dry mass), soak at room temperature (25°C) for 24 h, and stir every 8 h during the soaking.

[0030] 3) Microwave heating softening: take out the soaked blocky bamboo waste, rinse with clean water until pH=7, put it into a microwave heating softening machine, set the power to 400 W, and the processing time to 4 min, after degumming and softening and shaping, naturally cool to room temperature.

[0031] 4) Physical treatment (cutting + carding + dehydration): Cutting treatment: put the softened blocky bamboo waste into a knife roll bamboo cutting machine, adjust the tool spacing, and cut it into granular bamboo waste with a length of 6-8 mm and a width of 4-5 mm; Carding treatment: put the granular bamboo waste into a carding machine, set the carding speed to 300 r / min, and card twice to obtain a mixture of fibrous and powdery materials; Dehydration treatment: transfer the mixture to a dehydration machine, add 3 times the mass of clean water, high-speed stir (800 r / min) for 30 min, so that the cellulose part is suspended in water and the non-cellulose part is deposited; use centrifugal separation (5000 r / min, 15 min) to collect the suspended cellulose part on the upper layer.

[0032] 5) Drying: dry the separated cellulose at 60°C for 24h to obtain fluffy bamboo raw fibers.

[0033] After detection, the fluffy bamboo raw fibers obtained in this embodiment have a diameter of 35-120 μm, a length of 20-25 nm, and account for 63% of the total mass of the blocky bamboo waste, and can be used to prepare high-strength shaving board and other green composite materials.

[0034] Example 3: Classification method for extracting natural bamboo fibers from scrap bamboo waste The embodiment is directed to blocky bamboo waste (5-15 mm in length), and natural bamboo fibers are extracted by "mechanical screening-physical + biological combined method", and the specific steps are as follows: 1) Mechanical screening and cleaning: The shavings of bamboo waste are put into a vibrating screen (screen mesh aperture 1 mm), the vibration frequency is adjusted to 35 Hz, and the amplitude is 3 mm. Large particle impurities are removed by screening to obtain pure shavings of bamboo waste. The shavings are washed with clean water until the effluent is clear, and then the water is drained.

[0035] 2) Alkali immersion: The cleaned shavings of bamboo waste are placed in a mixed alkali solution (same as in Example 1, NaOH 50 g / L, JFC penetrant 3 g / L, and Na2SO3 2% of the dry mass), and soaked at room temperature (25°C) for 24 h, with continuous stirring (100 r / min) during the soaking.

[0036] 3) Microwave heating softening: The soaked shavings of bamboo waste are taken out, washed with clean water until the pH is 7, and then put into a microwave heating softening machine. The power is set to 400 W, and the treatment time is 6 min. After degumming and softening and shaping, the shavings are naturally cooled to room temperature.

[0037] 4) Physical treatment (grinding): The softened shavings of bamboo waste are put into a planetary ball mill with a zirconia ball mill tank (ball-to-material ratio 5:1). The rotation speed is set to 400 r / min, and the grinding time is 20 min. Granular material with a particle size of ≤16 μm is obtained.

[0038] 5) Biological treatment (enzymatic hydrolysis): Preparation of the mixed solution: The ground material is mixed with a complex enzyme solution (containing polygalacturonase 1%, pectinase 0.5%, and xylanase 0.8%, with the rest being water) at a mass ratio of 1:20. 0.3% (based on the total mass of the mixed solution) of a catalyst (ferrous sulfate) is added. Enzymatic hydrolysis reaction: The mixed solution is placed in a high-pressure reaction kettle and reacted at 160°C under pressure (0.5 MPa) for 3 h. The non-cellulose components are degraded into soluble products.

[0039] 6) Centrifugation and drying: The enzymatically hydrolyzed mixed solution is centrifuged at 8000 r / min for 20 min, and the precipitated cellulose part is collected. The cellulose is freeze-dried at -30°C for 36 h to obtain powdered bamboo raw fibers.

[0040] It is detected that the particle size of the powdered bamboo raw fibers obtained in this example is 8-16 μm, accounting for 55% of the total mass of the shavings of bamboo waste, and can be used to prepare bamboo fiber reinforced PE composite boards, bamboo-based bioplastics, etc.

[0041] Although the present application has been described with reference to the embodiments above, various changes and modifications can be suggested to one skilled in the art, and it is intended that the present application encompass such changes and modifications as fall within the scope of the appended claims. Particularly, each feature disclosed in the description and / or the claims can be used in the combination with each of the features disclosed in the description and / or the claims, unless specifically stated otherwise. Therefore, the present application is not intended to be limited to the particular embodiments disclosed in the description and / or the claims.

Claims

1. A graded method of industrial extraction of natural bamboo fibers from solid bamboo waste, characterized by, The steps are as follows: S1, mechanically screening and grading the solid bamboo waste to obtain at least one of bamboo waste in the form of sheet, block and scrap; S2, sequentially washing, alkali immersion and microwave heating softening treatment on the graded bamboo waste; S3, processing the bamboo waste in different forms by physical treatment combined with chemical treatment, physical treatment alone or physical treatment combined with biological treatment to obtain natural bamboo fibers in different forms and sizes.

2. A method of fractionation of natural bamboo fibers from solid bamboo waste as claimed in claim 1, wherein, The mechanical screening and grading is realized by a vibrating screen, and the bamboo waste in the form of sheet, block and scrap is screened according to the size difference from top to bottom.

3. A method of fractionation of natural bamboo fibers from solid bamboo waste as claimed in claim 1, wherein, The conditions of the alkali immersion are as follows: the bamboo waste is immersed in a mixed alkali solution containing NaOH, Na2SO3 and JFC penetrant for 24 hours at room temperature. Among them, the concentration of NaOH is 50g / L, the concentration of JFC penetrant is 3g / L, and the amount of Na2SO3 added is 2% of the dry mass of the bamboo waste.

4. A method of fractionation of natural bamboo fibers from solid bamboo waste as claimed in claim 1, wherein, The parameters of the microwave heating softening treatment are as follows: microwave power 400W, treatment time 4-6min.

5. A method of fractionation of natural bamboo fibers from solid bamboo waste as claimed in claim 1, wherein, For the sheet-shaped bamboo waste, the physical treatment combined with chemical treatment is adopted, which specifically includes: Physical treatment: sequentially performing pressure cracking treatment and disc grinding treatment, the pressure cracking treatment is hot pressing under the condition of 150℃ and 0.2MPa, and the breathing interval is 5min, and the disc grinding treatment adopts three-disc single-acting disc grinder; Chemical treatment: mixing the product after physical treatment with an alkaline solution at a mass ratio of 1:10-20, reacting in a water bath at 30-40℃ for 60-90min, and obtaining silk-like bamboo raw fibers after freeze-drying and vacuum drying.

6. A method of industrial extraction of natural bamboo fibers from solid bamboo waste according to claim 1, characterized by, For the block-shaped bamboo waste, the physical treatment alone is adopted, which specifically includes: Cutting treatment: cutting the block-shaped bamboo waste into granular shape with a length of 5-10mm and a width of 3-6mm by a knife roll cutting machine; Combing treatment: decomposing the granular bamboo waste to form fibrous and powdery materials; Dewatering treatment: separating cellulose and non-cellulose components by high-speed stirring and shearing force to obtain velvet-like bamboo raw fibers.

7. A method as claimed in claim 1, wherein the said method is an industrialized grading method for extracting natural bamboo fibers from solid bamboo waste. For the scrap-shaped bamboo waste, the physical treatment combined with biological treatment is adopted, which specifically includes: Physical treatment: grinding for 20min with a planetary ball mill with zirconia ball mill tank; Biological treatment: mixing the ground material with a composite enzyme solution, adding a catalyst, and then treating at 160℃ for 3h; Centrifugal treatment: centrifuging at a speed of 3000-10000r / min for 10-30min, and obtaining powdery bamboo raw fibers after cold drying at 60-30℃ for 12-36h.

8. A method of industrial extraction of natural bamboo fibers from solid bamboo waste according to claim 1, characterized by, In the prepared natural bamboo fibers, the total proportion of bamboo raw fibers is ≥60%; among them, the proportion of silk-like bamboo raw fibers is ≥70%, the proportion of velvet-like bamboo raw fibers is ≥60%, and the proportion of powdery bamboo raw fibers is ≥50%.

9. A method of industrial extraction of natural bamboo fibers from solid bamboo waste according to claim 7, characterized by, The composite enzyme solution includes polygalacturonate lyase, pectin lyase, polygalacturonate hydrolase, pectin hydrolase, pectin esterase, xylanase and glucanase.

10. A method of industrial extraction of natural bamboo fibers from solid bamboo waste according to claim 1, characterized by, The solid bamboo waste includes naturally occurring sheet-shaped, block-shaped and scrap-shaped bamboo waste or a combination of at least two of them.

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