Compound enzyme preparation for pulping arrowhead pulp and application of compound enzyme preparation

Abstract

The invention belongs to the technical field of papermaking, and particularly relates to a compound enzyme preparation for pulping arrowhead pulp and application of the compound enzyme preparation. The complex enzyme preparation provided by the invention comprises xylanase and lysing polysaccharide monooxygenase, and further comprises mannase or feruloyl esterase. The compound enzyme preparation can remarkably improve the pulping effect of the arrowhead pulp, reduce the pulping energy consumption and increase the kink index, the water retention value and the brooming degree of fibers. After neosinocalamus affinis chemithermomechanical pulp and neosinocalamus affinis chemical pulp treated by the compound enzyme preparation are subjected to sheet making to form paper, the burst index and tensile strength of the paper are improved, and the paper shows excellent physical properties.

Description

Technical Field

[0001] This invention belongs to the field of papermaking technology, specifically relating to a compound enzyme preparation for beating bamboo pulp and its application. Background Technology

[0002] Bamboo stalks (Phyllostachys edulis) are an important clumping bamboo species in southwestern my country, characterized by rapid growth and high yield, making them an excellent raw material for pulping and papermaking. Bamboo stalk pulp mainly includes two types: chemimechanical pulp and chemical pulp. The dense cell wall structure of bamboo fibers, particularly the tight binding of non-cellulose components (such as hemicellulose and lignin) with cellulose, leads to high energy consumption and low efficiency in traditional pulping methods. To achieve the target freeness, it is often necessary to extend the pulping time or increase the pulping intensity, which not only exacerbates energy consumption but also easily causes excessive fiber cutting, reducing paper strength. To reduce pulping energy consumption and improve pulping quality, bio-enzymes are considered a green and efficient solution and have received widespread attention.

[0003] While cellulase can degrade cellulose, its target sites are mostly amorphous regions, making it inefficient at dense crystalline regions, which are the main sources of energy consumption in pulping. However, when cellulase is used in pulping experiments, although it can improve freeness, it can also easily over-degrade the overall structure of cellulose, causing excessive fiber breakage and reducing the physical strength of the paper. Summary of the Invention

[0004] To address the above problems, this invention provides a compound enzyme preparation for beating bamboo pulp and its application. This compound enzyme preparation can significantly improve the beating efficiency of both mechanical and chemical bamboo pulp, reduce beating energy consumption, and simultaneously improve the physical properties of paper.

[0005] To achieve the above-mentioned objectives, the present invention adopts the following technical solution: The first aspect of the present invention provides a compound enzyme preparation for pulping bamboo pulp, the compound enzyme preparation comprising xylanase and lytic polysaccharide monooxygenase (LPMO), and further comprising mannanase or ferulic acid esterase.

[0006] The cleavable polysaccharide monooxygenase can assist in the degradation of cellulose and hemicellulose. Its mechanism of action is not through hydrolysis, but through oxidation to directly destroy the crystalline cellulose structure, which efficiently achieves internal swelling and fiber separation of the fiber, thereby reducing pulping energy consumption. Moreover, the action mode is gentle and can preserve the integrity and strength of the fiber to the greatest extent.

[0007] Xylanase and mannanase are hemicellulases that can weaken the compactness of fiber structure by enzymatically hydrolyzing the hemicellulose components in the fiber cell wall, thereby softening the fiber and improving pulping effect.

[0008] Ferulic acid esterase relaxes the structure of fiber cell walls by breaking the "bond bridge" between lignin and hemicellulose, making the fibers easier to absorb water, swell, and fibrillate during mechanical pulping, thereby significantly reducing pulping energy consumption and improving pulping efficiency.

[0009] This invention creatively combines the above-mentioned enzymes to obtain the composite enzyme preparation. When the composite enzyme preparation is used for beating bamboo pulp, it can significantly improve the beating effect of bamboo pulp and reduce beating energy consumption, increase the fiber kink index, water retention value and fissuring degree, and improve the bursting index and tensile strength of pulp and paper, resulting in paper exhibiting excellent physical properties.

[0010] Preferably, the compound enzyme preparation comprises xylanase, cleaving polysaccharide monooxygenase, and mannanase, wherein the enzyme activity ratio of xylanase, cleaving polysaccharide monooxygenase, and mannanase is (20~40):(6~8):(25~45). This compound enzyme preparation can effectively improve the pulping effect of bamboo stalk mechanical pulp.

[0011] More preferably, the enzyme activity ratio of the xylanase, the cleaving polysaccharide monooxygenase, and the mannanase is 20:10:35.

[0012] Preferably, the compound enzyme preparation comprises xylanase, cleaving polysaccharide monooxygenase, and ferulic acid esterase, wherein the enzyme activity ratio of xylanase, cleaving polysaccharide monooxygenase, and ferulic acid esterase is (20~40):(4~8):(10~20). This compound enzyme preparation can effectively improve the pulping effect of bamboo chemical pulp.

[0013] Preferably, the enzyme activity ratio of xylanase, cleaving polysaccharide monooxygenase and ferulic acid esterase is 20:20:4.

[0014] The second aspect of this invention provides the application of the above-mentioned compound enzyme preparation in the mechanical pulping of bamboo.

[0015] The third aspect of this invention provides the application of the above-mentioned compound enzyme preparation in the pulping of bamboo chemical pulp.

[0016] The fourth aspect of this invention provides a method for pulping bamboo, specifically including the following steps: S1. Soak the bamboo pulp board in water for at least 4 hours, then tear it into pulp sheets. After the pulp sheets are dispersed evenly into the fiber in the pulp, take them out, spin off the water, break them up, and balance the moisture to obtain a standardized bamboo pulp wet pulp with uniform moisture content. S2. Add water to the standardized bamboo pulp wet slurry to adjust the slurry concentration to 2%~4%, heat to 40~50℃, add the compound enzyme preparation and react for 1.8~2.2 h, then terminate the enzyme reaction; filter, add water to the filter cake obtained by vacuum filtration to adjust the slurry concentration to 8%~12%; S3. The slurry obtained in S2 is pulped with a grinding gap of 0.15~0.2 mm and a grinding speed of 4000~8500 r.

[0017] In this method, "pulp concentration" has the conventional meaning of pulp concentration in the pulp and paper industry, expressed as the number of grams of oven-dry pulp per 100 mL of pulp. For example, a pulp concentration of 2% means that the mass of oven-dry pulp per 100 mL of pulp is 2 g.

[0018] Preferably, in step S1, the bamboo pulp board is soaked in water for 8-12 hours. This time range ensures that the bamboo pulp board is fully soaked in water. Within this time range, the soaking time has no significant impact on the final pulping effect or the physical properties of the paper.

[0019] Preferably, the size of the paddle in S1 is 4 cm × 4 cm.

[0020] Preferably, in step S2, water is added to the standardized bamboo pulp wet slurry to adjust the slurry concentration to 3%, and after heating to 43~47℃, the compound enzyme preparation is added and reacted for 2 hours, and then the enzyme reaction is terminated; the mixture is filtered, and water is added to the filter cake obtained by filtration to adjust the slurry concentration to 10%.

[0021] Preferably, when the *Cymbidium faberi* pulp is a chemimechanical pulp, the composite enzyme preparation in S2 includes xylanase, a polysaccharide-lysing monooxygenase, and mannanase. The amount of xylanase added is 20-40 U / g, the amount of the polysaccharide-lysing monooxygenase added is 6-8 U / g, and the amount of mannanase added is 25-45 U / g. "U / g" refers to the enzyme activity per gram of oven-dry *Cymbidium faberi* pulp.

[0022] Preferably, when the *Ciba* pulp is a chemical pulp of *Ciba*, the complex enzyme preparation in S2 includes xylanase, cleaving polysaccharide monooxygenase, and ferulic acid esterase. The amount of xylanase added is 20-40 U / g, the amount of cleaving polysaccharide monooxygenase added is 4-8 U / g, and the amount of ferulic acid esterase added is 10-20 U / g.

[0023] Preferably, the reaction in S2 is stirred for 4 to 6 minutes every 7 to 13 minutes. For example, it can be stirred for 5 minutes every 10 minutes.

[0024] Preferably, the method for terminating the enzyme reaction in S2 is to place the reaction system in a boiling water bath for 5 minutes.

[0025] The fifth aspect of the present invention provides the application of the above method in papermaking using bamboo as raw material.

[0026] The beneficial effects of this invention are: enzymatic beating using the invented compound enzyme preparation can effectively improve beating efficiency, reduce beating energy consumption, and significantly improve the physical properties of pulp and paper. Experiments have shown that the invented compound enzyme preparation can reduce beating energy consumption of bamboo chemimechanical pulp and chemical pulp by 26.09% and 20.59%, respectively, and can increase the tensile index and burst index of bamboo chemimechanical pulp paper by 20.90% and 13.59%, respectively, and increase the tensile index and burst index of bamboo chemical pulp paper by 5.66% and 1.26%, respectively. Attached Figure Description

[0027] Figure 1 This is the result of measuring the freeness of bamboo stalk mechanical pulp before and after treatment with different concentrations of xylanase in Example 2 of this invention. Figure 2 This is the result of measuring the freeness of bamboo mechanical pulp before and after treatment with different concentrations of mannanase in Example 2 of this invention; Figure 3 This is the result of measuring the freeness of bamboo pulp before and after beating with different concentrations of cellulase in Example 2 of this invention. Figure 4 This is the result of measuring the freeness of bamboo pulp before and after beating with different concentrations of LPMO in Example 2 of this invention. Figure 5 This is the measurement result of the freeness of bamboo pulp before and after treatment with different concentrations of xylanase in Example 2 of the present invention; Figure 6 This is the result of measuring the freeness of bamboo chemical pulp before and after treatment with different concentrations of mannanase in Example 2 of this invention; Figure 7 This is the result of measuring the degree of freeness of *Phyllostachys edulis* before and after chemical pulping with different concentrations of ferulic acid esterase in Example 2 of this invention. Figure 8 This is the result of measuring the freeness of bamboo chemical pulp before and after treatment with different concentrations of cellulase in Example 2 of this invention. Figure 9 This is the result of measuring the freeness of bamboo chemical pulp before and after beating with different concentrations of LPMO in Example 2 of this invention. Figure 10 These are scanning electron microscope images of the cylindrical pulp and chemical pulp of *Cymbidium goeringii* obtained by different treatment methods in Example 4 of this invention. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. All other embodiments obtained by those skilled in the art based on the implementation methods of this invention without inventive effort fall within the protection scope of this invention.

[0029] Traditional beating of bamboo pulp suffers from high energy consumption and low efficiency. Achieving the desired degree of freeness requires extending the beating time or increasing the beating intensity, which not only consumes a lot of energy but also easily causes excessive fiber cutting, damaging paper strength. While bio-enzymes, such as cellulase, can degrade cellulose, improve freeness, and reduce energy consumption, they also tend to cause excessive fiber cutting, leading to a decrease in the physical strength of the paper, and their application effect is not entirely ideal.

[0030] To address this problem, embodiments of the present invention provide a compound enzyme preparation for beating bamboo pulp. This compound enzyme preparation includes xylanase and lysin-degrading polysaccharide monooxygenase (LPMO), and also includes mannanase or ferulic acid esterase. Using this compound enzyme preparation for beating bamboo pulp can significantly improve the beating effect and reduce beating energy consumption, while also improving the physical properties of the pulp and paper.

[0031] This invention also provides the application of the above-mentioned compound enzyme preparation in the mechanical pulping of bamboo.

[0032] This invention also provides the application of the above-mentioned compound enzyme preparation in the pulping of bamboo chemical pulp.

[0033] This invention also provides a method for pulping bamboo, specifically including the following steps: S1. Soak the bamboo pulp board in water for at least 4 hours, then tear it into pulp sheets. After the pulp sheets are dispersed evenly into the fiber in the pulp, take them out, spin off the water, break them up, and balance the moisture to obtain a standardized bamboo pulp wet pulp with uniform moisture content. S2. Add water to the standardized bamboo pulp wet slurry to adjust the slurry concentration to 2%~4%, heat to 40~50℃, add the compound enzyme preparation and react for 1.8~2.2 h, then terminate the enzyme reaction; filter, add water to the filter cake obtained by vacuum filtration to adjust the slurry concentration to 8%~12%; S3. The slurry obtained in S2 is pulped with a grinding gap of 0.15~0.2 mm and a grinding speed of 4000~8500 r.

[0034] This invention also provides the application of the above method in papermaking.

[0035] The present invention will be described below through specific embodiments.

[0036] In the following examples, "U / g" refers to the enzyme activity per gram of oven-dried bamboo pulp. For example, "xylanase 20 U / g" means that 20 U of xylanase is added per gram of oven-dried bamboo pulp. The term "pulp concentration" in the following examples has the conventional meaning in the pulp and paper industry, expressed as grams of oven-dried pulp per 100 mL of pulp. For example, a pulp concentration of 3% means that the mass of oven-dried pulp per 100 mL of pulp is 3 g.

[0037] The slurry boards used in the following examples were provided by the School of Light Industry Science and Engineering, Tianjin University of Science and Technology, and were natural-colored slurry boards. Cellulase and mannanase were provided by Baiyin Sainuo Biotechnology Co., Ltd.; xylanase was purchased from Shandong Sukehan Bioengineering Co., Ltd.; ferulic acid esterase was purchased from Guangdong Fangxin Biotechnology Co., Ltd.; other chemical reagents were all domestic brands.

[0038] The main equipment and instruments used in the following examples are: V-type PFI refiner (Norwegian Pulp and Paper Institute); TENSOR 27 Fourier transform infrared spectrometer (Bruck GmbH, Germany); Fiber Tester 912 fiber bundle analyzer (L&W GmbH, Sweden); LEO 1530VP scanning electron microscope (Carl Zeiss GmbH, Germany); 062 969921 tensile strength tester (L&W GmbH, Sweden); SE051 tear tester (L&W GmbH, Sweden); and 02 9699 20 burst strength tester (L&W GmbH, Sweden).

[0039] Unless otherwise specified, the technical means used in the following embodiments are conventional means well known to those skilled in the art; the materials and reagents used in the following embodiments are all commercially available.

[0040] Example 1 This embodiment provides a compound enzyme preparation for pulping bamboo pulp, which consists of xylanase, mannanase and LPMO, with an enzyme activity ratio of xylanase, mannanase and LPMO of 20:25:6.

[0041] Example 2 This embodiment provides a compound enzyme preparation for pulping bamboo pulp, which consists of xylanase, mannanase and LPMO, with an enzyme activity ratio of xylanase, mannanase and LPMO of 20:35:10.

[0042] Example 3 This embodiment provides a compound enzyme preparation for pulping bamboo pulp, which consists of xylanase, mannanase and LPMO, with an enzyme activity ratio of xylanase, mannanase and LPMO of 20:45:8.

[0043] Example 4 This embodiment provides a compound enzyme preparation for pulping bamboo pulp, which consists of xylanase, mannanase and LPMO, with an enzyme activity ratio of 30:25:10 for xylanase, mannanase and LPMO.

[0044] Example 5 This embodiment provides a compound enzyme preparation for pulping bamboo pulp, which consists of xylanase, mannanase and LPMO, with an enzyme activity ratio of 30:35:8.

[0045] Example 6 This embodiment provides a compound enzyme preparation for pulping bamboo pulp, which consists of xylanase, mannanase and LPMO, with an enzyme activity ratio of 30:45:6.

[0046] Example 7 This embodiment provides a compound enzyme preparation for pulping bamboo pulp, which consists of xylanase, mannanase and LPMO, with an enzyme activity ratio of xylanase, mannanase and LPMO of 40:25:8.

[0047] Example 8 This embodiment provides a compound enzyme preparation for pulping bamboo pulp, which consists of xylanase, mannanase and LPMO, with an enzyme activity ratio of xylanase, mannanase and LPMO of 40:35:6.

[0048] Example 9 This embodiment provides a compound enzyme preparation for pulping bamboo pulp, which consists of xylanase, mannanase and LPMO, with an enzyme activity ratio of 40:45:10.

[0049] Examples 10 to 18 Examples 10 to 18 respectively provide a method for mechanical pulping of *Cymbidium goeringii*, the specific steps of which are as follows: (1) Pretreatment method for Cizhu chemical mechanical pulp Soak the bamboo pulp board in water overnight (8-12 hours), then tear it into 4 cm × 4 cm pieces. Use a pulp descrambling machine to descramble the pulp pieces until the fibers in the pulp are evenly dispersed. Remove the pulp, spin dry, break it up, and place it in a sealed bag. Place it in a 4°C refrigerator overnight (8-12 hours) to balance the moisture and obtain a standardized bamboo pulp wet pulp with uniform moisture content. (2) Enzyme treatment Take the standardized bamboo pulp wet slurry obtained in step (1), place it in a 1000 ml glass beaker, add water to adjust the slurry concentration to 3%, preheat it in a 45 ℃ constant temperature water bath, and when the slurry temperature reaches 45 ℃, add the compound enzyme preparations from Examples 1 to 9 respectively, react under natural pH conditions for 2 h (stirring for 5 min every 10 min during this period), and then place it in boiling water for 5 min to terminate the enzyme reaction. Filter it using a Buchner funnel to obtain a slurry cake. Add water to the filtered slurry cake to adjust the slurry concentration to 10%. The source and amount of the compound enzyme preparations added in each example are shown in Table 1.

[0050] Table 1. Amounts of various enzymes added in Examples 10 to 18

[0051] (3) Pulping treatment The 10% slurry from step (2) was ground using a PFI grinder with a grinding gap of 0.2 mm and a grinding speed of 4000 r, and the ground slurry was collected.

[0052] Example 19 This embodiment provides a compound enzyme preparation for pulping bamboo pulp, which consists of xylanase, ferulic acid esterase and LPMO, with an enzyme activity ratio of xylanase, ferulic acid esterase and LPMO of 20:10:4.

[0053] Example 20 This embodiment provides a compound enzyme preparation for pulping bamboo pulp, which consists of xylanase, ferulic acid esterase and LPMO, with an enzyme activity ratio of xylanase, ferulic acid esterase and LPMO of 20:15:8.

[0054] Example 21 This embodiment provides a compound enzyme preparation for pulping bamboo pulp, which consists of xylanase, ferulic acid esterase and LPMO, with the enzyme activity ratio of xylanase, ferulic acid esterase and LPMO being 20:20:6.

[0055] Example 22 This embodiment provides a compound enzyme preparation for pulping bamboo pulp, which consists of xylanase, ferulic acid esterase and LPMO, with an enzyme activity ratio of 30:10:8.

[0056] Example 23 This embodiment provides a compound enzyme preparation for pulping bamboo pulp, which consists of xylanase, ferulic acid esterase and LPMO, with an enzyme activity ratio of 30:20:4.

[0057] Example 24 This embodiment provides a compound enzyme preparation for pulping bamboo pulp, which consists of xylanase, ferulic acid esterase and LPMO, with an enzyme activity ratio of xylanase, ferulic acid esterase and LPMO of 40:10:6.

[0058] Example 25 This embodiment provides a compound enzyme preparation for pulping bamboo pulp, which consists of xylanase, ferulic acid esterase and LPMO, with an enzyme activity ratio of xylanase, ferulic acid esterase and LPMO of 40:15:4.

[0059] Example 26 This embodiment provides a compound enzyme preparation for pulping bamboo pulp, which consists of xylanase, ferulic acid esterase and LPMO, with the enzyme activity ratio of xylanase, ferulic acid esterase and LPMO being 20:20:6.

[0060] Examples 27 to 36 Examples 27 to 36 respectively provide a method for pulping bamboo chemical pulp, the specific steps of which are as follows: (1) Pretreatment method of bamboo chemical pulp Soak the bamboo chemical pulp board in water overnight (8-12 hours), then tear it into 4 cm × 4 cm pulp sheets. Use a pulp descrambling machine to descramble the pulp sheets until the fibers in the pulp are evenly dispersed. Remove the pulp sheets, shake off the water, break them up, and place them in a sealed bag. Place them in a 4℃ refrigerator overnight (8-12 hours) to balance the moisture content and obtain standardized bamboo wet pulp with uniform moisture content.

[0061] (2) Enzyme treatment Take the standardized bamboo pulp wet slurry obtained in step (1), place it in a 1000 ml glass beaker, add water to adjust the slurry concentration to 3%, preheat it in a 45 ℃ constant temperature water bath, and when the slurry temperature reaches 45 ℃, add the enzyme preparations from Examples 19 to 26 respectively (wherein the enzyme preparation of Example 19 is added in different amounts in different examples), react under natural pH conditions for 2 h (stirring for 5 min every 10 min during this period), and then place it in boiling water for 5 min to terminate the enzyme reaction. Filter it using a Buchner funnel to obtain a slurry cake. Add water to the filtered slurry cake to adjust the slurry concentration to 10%. The source and amount of the compound enzyme preparation added in each example are shown in Table 2.

[0062] Table 2. Amounts of various enzymes added in Examples 27 to 36

[0063] (3) Pulping treatment The 10% slurry from step (2) was ground using a PFI grinder with a grinding gap of 0.2 mm and a grinding speed of 4000 r, and the ground slurry was collected.

[0064] Test Example 1 The freeness of the pulp obtained using Examples 10-18 and Examples 27-36 was determined. The method was as follows: 20.00 g of pulp was weighed, added to distilled water at 20°C, diluted, and brought to a final volume of 1000 ml, at which point the pulp concentration was 0.2%. The mixture was thoroughly stirred and then quickly poured into the raised side-flow tube of the freeness tester, sealed with a conical nozzle. The conical nozzle was then smoothly and quickly removed, allowing the pulp to filter under gravity. Water passed through the sieve, while fibers were retained. Once the water flow in the side-flow tube stopped, the scale value on the bottom tube was immediately read. This value is the freeness value of the pulp, expressed in °SR.

[0065] The measurement results of Examples 10 to 18 are shown in Table 3.

[0066] Table 3. Measurement results of Examples 10 to 18

[0067] The measurement results of Examples 27 to 36 are shown in Table 4.

[0068] Table 4. Measurement results of Examples 27 to 36

[0069] Example 37 This embodiment provides a method for pulping bamboo stalks using mechanical pulping, the specific steps of which are as follows: (1) Pretreatment method of Cizhu chemical mechanical pulp: same as in Example 10.

[0070] (2) Enzyme treatment Take the standardized bamboo pulp wet slurry obtained in step (1), place it in a 1000 ml glass beaker, add water to adjust the slurry concentration to 3%, preheat it in a 45 ℃ constant temperature water bath, and when the slurry temperature reaches 45 ℃, add the compound enzyme preparation from Example 2 (addition amount: xylanase 20 U / g, mannanase 35 U / g, LPMO 10 U / g), react under natural pH conditions for 2 h (stirring for 5 min every 10 min during this period), then place it in boiling water for 5 min to terminate the enzyme reaction, filter it using a Buchner funnel to obtain a slurry cake. Add water to the filtered slurry cake to adjust the slurry concentration to 10%.

[0071] (3) Pulping treatment The 10% slurry from step (2) was ground using a PFI grinder with a grinding gap of 0.15 mm and a grinding speed of 8500 r, and the ground slurry was collected.

[0072] Example 38 This embodiment provides a method for pulping bamboo chemical pulp, the specific steps of which are as follows: (1) Pretreatment method of bamboo chemical pulp: same as in Example 27.

[0073] (2) Enzyme treatment Take the standardized bamboo pulp wet slurry obtained in step (1), place it in a 1000 ml glass beaker, add water to adjust the slurry concentration to 3%, preheat it in a 45 ℃ constant temperature water bath, and when the slurry temperature reaches 45 ℃, add the compound enzyme preparation from Example 26 (addition amount: xylanase 20 U / g, ferulic acid esterase 20 U / g, LPMO 4 U / g), react under natural pH conditions for 2 h (stirring for 5 min every 10 min during this period), then place it in boiling water for 5 min to terminate the enzyme reaction, filter it using a Buchner funnel to obtain a slurry cake. Add water to the filtered slurry cake to adjust the slurry concentration to 10%.

[0074] (3) Pulping treatment The 10% slurry from step (2) was ground using a PFI grinder with a grinding gap of 0.15 mm and a grinding speed of 7000 r, and the ground slurry was collected.

[0075] Comparative Example 1 This comparative example provides a method for mechanical pulping of *Cymbidium goeringii*, with the specific steps as follows: (1) Pretreatment method of Cizhu chemical mechanical pulp: same as in Example 10.

[0076] (2) Water treatment Take the standardized bamboo pulp wet slurry obtained in step (1), place it in a 1000 ml glass beaker, add water to adjust the slurry concentration to 3%, preheat it in a 45 ℃ constant temperature water bath, and when the slurry temperature reaches 45 ℃, keep it at the natural pH condition for 2 hours (stirring for 5 minutes every 10 minutes during this period), then place it in boiling water and keep it at that temperature for 5 minutes. Filter it using a Buchner funnel to obtain a slurry cake. Add water to the filtered slurry cake to adjust the slurry concentration to 10%.

[0077] (3) Pulping treatment: The 10% slurry from step (2) is pulped using a PFI mill with a grinding gap of 0.15 mm and a grinding speed of 8000 r, and the pulped slurry is collected.

[0078] Comparative Examples 2-5 Comparative Examples 2-5 each provide a method for mechanical pulping of *Cymbidium goeringii*, with the specific steps as follows: (1) Pretreatment method of Cizhu chemical mechanical pulp: same as in Example 10.

[0079] (2) Enzyme treatment Take the standardized bamboo pulp wet slurry obtained in step (1), place it in a 1000 ml glass beaker, add water to adjust the slurry concentration to 3%, preheat it in a 45 ℃ constant temperature water bath, and when the slurry temperature reaches 45 ℃, add 10 U / g, 20 U / g, 30 U / g, and 40 U / g xylanase respectively, react under natural pH conditions for 2 h (stirring for 5 min every 10 min during this period), then place it in boiling water for 5 min to terminate the enzyme reaction, filter it using a Buchner funnel to obtain a slurry cake. Add water to the filtered slurry cake to adjust the slurry concentration to 10%.

[0080] (3) Pulping treatment: Same as comparative example 1.

[0081] Comparative Examples 6-9 Comparative Examples 6-9 each provide a method for mechanical pulping of *Cymbidium goeringii*, with the specific steps as follows: (1) Pretreatment method of Cizhu chemical mechanical pulp: same as in Example 10.

[0082] (2) Enzyme treatment Take the standardized bamboo pulp wet slurry obtained in step (1), place it in a 1000 ml glass beaker, add water to adjust the slurry concentration to 3%, preheat it in a 45 ℃ constant temperature water bath, and when the slurry temperature reaches 45 ℃, add 15 U / g, 25 U / g, 35 U / g, and 45 U / g mannanase respectively, react under natural pH conditions for 2 h (stirring for 5 min every 10 min during this period), then place it in boiling water for 5 min to terminate the enzyme reaction, filter it using a Buchner funnel to obtain a slurry cake. Add water to the filtered slurry cake to adjust the slurry concentration to 10%.

[0083] (3) Pulping treatment: Same as comparative example 1.

[0084] Comparative Examples 10-13 Comparative Examples 10-13 each provide a method for mechanical pulping of *Cymbidium goeringii*, with the specific steps as follows: (1) Pretreatment method of Cizhu chemical mechanical pulp: same as in Example 10.

[0085] (2) Enzyme treatment Take the standardized bamboo pulp wet slurry obtained in step (1), place it in a 1000 ml glass beaker, add water to adjust the slurry concentration to 3%, preheat it in a 45 ℃ constant temperature water bath, and when the slurry temperature reaches 45 ℃, add 4 U / g, 6 U / g, 8 U / g, and 10 U / g cellulase respectively, react under natural pH conditions for 2 h (stirring for 5 min every 10 min during this period), then place it in boiling water for 5 min to terminate the enzyme reaction, filter it using a Buchner funnel to obtain a slurry cake. Add water to the filtered slurry cake to adjust the slurry concentration to 10%.

[0086] (3) Pulping treatment: Same as comparative example 1.

[0087] Comparative Examples 14-17 Comparative Examples 14-17 each provide a method for mechanical pulping of *Cymbidium goeringii*, with the specific steps as follows: (1) Pretreatment method of Cizhu chemical mechanical pulp: same as in Example 10.

[0088] (2) Enzyme treatment Take the standardized bamboo pulp wet slurry obtained in step (1), place it in a 1000 ml glass beaker, add water to adjust the slurry concentration to 3%, preheat in a 45 ℃ constant temperature water bath, and when the slurry temperature reaches 45 ℃, add 4 U / g, 6 U / g, 8 U / g, and 10 U / g LPMO respectively, react under natural pH conditions for 2 h (stirring for 5 min every 10 min during this period), then place it in boiling water for 5 min to terminate the enzyme reaction, filter using a Buchner funnel to obtain a slurry cake. Add water to the filtered slurry cake to adjust the slurry concentration to 10%.

[0089] (3) Pulping treatment: Same as comparative example 1.

[0090] Comparative Example 18 This comparative example provides a method for pulping bamboo chemical pulp, the specific steps of which are as follows: (1) Pretreatment method of bamboo chemical pulp: same as in Example 27.

[0091] (2) Water treatment Take the standardized bamboo pulp wet slurry obtained in step (1), place it in a 1000 ml glass beaker, add water to adjust the slurry concentration to 3%, preheat it in a 45 ℃ constant temperature water bath, and when the slurry temperature reaches 45 ℃, keep it at the natural pH condition for 2 hours (stirring for 5 minutes every 10 minutes during this period), then place it in boiling water and keep it at that temperature for 5 minutes. Filter it using a Buchner funnel to obtain a slurry cake. Add water to the filtered slurry cake to adjust the slurry concentration to 10%.

[0092] (3) Pulping treatment: Same as comparative example 1.

[0093] Comparative Examples 19-22 Comparative Examples 19-22 each provide a method for pulping *Bambusa textilis* using chemical pulp, with the specific steps as follows: (1) Pretreatment method of bamboo chemical pulp: same as in Example 27.

[0094] (2) Enzyme treatment Take the standardized bamboo pulp wet slurry obtained in step (1), place it in a 1000 ml glass beaker, add water to adjust the slurry concentration to 3%, preheat it in a 45 ℃ constant temperature water bath, and when the slurry temperature reaches 45 ℃, add 10 U / g, 20 U / g, 30 U / g, and 40 U / g xylanase respectively, react under natural pH conditions for 2 h (stirring for 5 min every 10 min during this period), then place it in boiling water for 5 min to terminate the enzyme reaction, filter it using a Buchner funnel to obtain a slurry cake. Add water to the filtered slurry cake to adjust the slurry concentration to 10%.

[0095] (3) Pulping treatment: Same as comparative example 1.

[0096] Comparative Examples 23-26 Comparative Examples 23-26 each provide a method for pulping *Bambusa textilis* using chemical pulp, with the specific steps as follows: (1) Pretreatment method of bamboo chemical pulp: same as in Example 27.

[0097] (2) Enzyme treatment Take the standardized bamboo pulp wet slurry obtained in step (1), place it in a 1000 ml glass beaker, add water to adjust the slurry concentration to 3%, preheat it in a 45 ℃ constant temperature water bath, and when the slurry temperature reaches 45 ℃, add 15 U / g, 25 U / g, 35 U / g, and 45 U / g mannanase respectively, react under natural pH conditions for 2 h (stirring for 5 min every 10 min during this period), then place it in boiling water for 5 min to terminate the enzyme reaction, filter it using a Buchner funnel to obtain a slurry cake. Add water to the filtered slurry cake to adjust the slurry concentration to 10%.

[0098] (3) Pulping treatment: Same as comparative example 1.

[0099] Comparative Examples 27-30 Comparative Examples 27-30 each provide a method for pulping *Bambusa textilis* using chemical pulp, with the specific steps as follows: (1) Pretreatment method of bamboo chemical pulp: same as in Example 27.

[0100] (2) Enzyme treatment Take the standardized bamboo pulp wet slurry obtained in step (1), place it in a 1000 ml glass beaker, add water to adjust the slurry concentration to 3%, preheat in a 45 ℃ constant temperature water bath, and when the slurry temperature reaches 45 ℃, add 5 U / g, 10 U / g, 15 U / g, and 20 U / g ferulic acid esterase respectively, react under natural pH conditions for 2 h (stirring for 5 min every 10 min during this period), then place it in boiling water for 5 min to terminate the enzyme reaction, filter using a Buchner funnel to obtain a slurry cake. Add water to the filtered slurry cake to adjust the slurry concentration to 10%.

[0101] (3) Pulping treatment: Same as comparative example 1.

[0102] Comparative Examples 31-34 Comparative Examples 31-34 each provide a method for pulping *Bambusa textilis* using chemical pulp, with the specific steps as follows: (1) Pretreatment method of bamboo chemical pulp: same as in Example 27.

[0103] (2) Enzyme treatment Take the standardized bamboo pulp wet slurry obtained in step (1), place it in a 1000 ml glass beaker, add water to adjust the slurry concentration to 3%, preheat it in a 45 ℃ constant temperature water bath, and when the slurry temperature reaches 45 ℃, add 4 U / g, 6 U / g, 8 U / g, and 10 U / g cellulase respectively, react under natural pH conditions for 2 h (stirring for 5 min every 10 min during this period), then place it in boiling water for 5 min to terminate the enzyme reaction, filter it using a Buchner funnel to obtain a slurry cake. Add water to the filtered slurry cake to adjust the slurry concentration to 10%.

[0104] (3) Pulping treatment: Same as comparative example 1.

[0105] Comparative examples 35-38 Comparative Examples 35-38 each provide a method for pulping *Bambusa textilis* using chemical pulp, with the specific steps as follows: (1) Pretreatment method of bamboo chemical pulp: same as in Example 27.

[0106] (2) Enzyme treatment Take the standardized bamboo pulp wet slurry obtained in step (1), place it in a 1000 ml glass beaker, add water to adjust the slurry concentration to 3%, preheat in a 45 ℃ constant temperature water bath, and when the slurry temperature reaches 45 ℃, add 4 U / g, 6 U / g, 8 U / g, and 10 U / g LPMO respectively, react under natural pH conditions for 2 h (stirring for 5 min every 10 min during this period), then place it in boiling water for 5 min to terminate the enzyme reaction, filter using a Buchner funnel to obtain a slurry cake. Add water to the filtered slurry cake to adjust the slurry concentration to 10%.

[0107] (3) Pulping treatment: Same as comparative example 1.

[0108] Test Example 2 Take the 10% slurry obtained in step (2) of Comparative Examples 1 to 38 and measure the freeness before slurrying using the method of Test Example 1. Then take the slurry obtained in step (3) of Comparative Examples 1 to 38 and measure the freeness after slurrying using the method of Test Example 1.

[0109] The test results of comparative examples 1-5 are as follows Figure 1 As shown, the measurement results of Comparative Examples 1, 6-9 are as follows: Figure 2 As shown, the measurement results of Comparative Examples 1, 10~13 are as follows: Figure 3 As shown, the measurement results of Comparative Examples 1, 14-17 are as follows: Figure 4 As shown: Compared to Comparative Example 1 (CK in the figure), enzymatic beating with different concentrations of xylanase, mannanase, cellulase, and LPMO effectively improved the freeness of bamboo pulp before and after beating. The highest freeness (SR) was achieved when xylanase was added at 30 U / g, reaching 20.00 °SR; when mannanase was added at 35 U / g, the highest freeness (SR) was achieved at 20.50 °SR; when cellulase was added at 4 U / g, the highest freeness (SR) was achieved at 19.50 °SR; and when LPMO was added at 8 U / g, the highest freeness (SR) was achieved at 23.20 °SR. However, when LPMO was added at 10 U / g, the freeness decreased significantly.

[0110] The determination results of comparative examples 18-22 are as follows Figure 5 As shown: When xylanase was added, there was no significant change in the freeness. The results for comparative examples 23-26 are as follows. Figure 6As shown, the beating degree did not change significantly when mannanase was added. This may be because the chemical pulp made from *Cymbidium faberi* contains a large amount of chemicals that remove most impurities and unstable hemicellulose from the fiber raw material. The resulting pulp has a more stable hemicellulose structure that is less susceptible to enzymatic hydrolysis.

[0111] The determination results of comparative examples 18 and 27-30 are as follows Figure 7 As shown, enzymatic beating with different concentrations of ferulic acid esterase can effectively improve the degree of beating. When the addition amount reaches 15 U / g, the degree of beating after beating is basically the highest, which is 36.83°SR.

[0112] The determination results of comparative examples 18 and 31-34 are as follows: Figure 8 As shown, when cellulase is used to treat pulp, the freeness of the pulp decreases after beating, indicating that cellulase treatment damages the chemical pulp fibers of *Bambusa textilis*.

[0113] The determination results of comparative examples 18 and 35-38 are as follows: Figure 9 As shown, when enzymatic beating is performed with different concentrations of LPMO, the degree of beating can be effectively improved. When the addition amount is 6 U / g, the degree of beating after beating reaches the highest level, which is 35.00°SR.

[0114] Test Example 3 The mechanical pulp of *Cymbidium goeringii* was treated using the methods of Example 37 and Comparative Example 1, and the chemical pulp of *Cymbidium goeringii* was treated using the methods of Example 38 and Comparative Example 18. Then, the pulp with a concentration of 10% in step (2) was refined using a PFI refiner (refining gap 0.15 mm). Under the condition that the freeness was basically the same, the refining revolutions and energy consumption were recorded. The results are shown in Table 5. Table 5 shows that, compared with untreated (Comparative Example 1) chemimechanical pulp, when achieving the same degree of freeness, the number of re-rating revolutions required for enzyme-treated chemimechanical pulp decreased from 12,000 r to 8,500 r, and the re-rating energy consumption decreased from 46 KJ to 34 KJ, a reduction of 26.09%. Similarly, compared with the untreated method (Comparative Example 18), when achieving essentially the same degree of freeness, the number of re-rating revolutions required for enzyme-treated chemimechanical pulp decreased from 9,000 r to 7,000 r, and the re-rating energy consumption decreased from 34 KJ to 27 KJ, a reduction of 20.59%.

[0115] Table 5. Effects of enzyme treatment on the energy consumption of pulping two types of bamboo pulp.

[0116] This may be because the fiber surface and internal structure are adjusted by the synergistic catalytic effect of the compound enzyme preparation in this application, the rigidity is reduced, the fiber becomes soft, and the fiber is easy to defibril during pulping, thereby improving the pulping degree and reducing pulping energy consumption; while the untreated bamboo mechanical pulp fiber has a low degree of surface fine fiberization due to the protection of the lignin-carbohydrate complex (LCC) on the fiber surface, and more pulping revolutions are required to break the fiber surface layer and achieve defibrilization during pulping, resulting in greater energy consumption.

[0117] Meanwhile, compared with the data in Test Examples 1 and 2, it can be seen that after treating the bamboo pulp with the compound enzyme preparation of the present invention, the degree of beating can be significantly increased when the beating speed is increased. Compared with the degree of beating of each comparative example, when the beating speed is similar, the bamboo pulp treated with the compound enzyme preparation of the present invention can obtain a significantly higher degree of beating. When the beating speed is only half that of the comparative examples, the degree of beating is close to or even higher than that achievable by most of the comparative examples.

[0118] These results indicate that the compound enzyme preparation of the present invention can effectively improve the beating degree and reduce beating energy consumption when treating bamboo pulp, whether it is mechanical or chemical pulp.

[0119] Test Example 4 The chemical pulp of *Bambusa textilis* was treated using the methods of Example 37 and Comparative Example 1, with the pulping parameters following step (3) of Example 37. The chemical pulp of *Bambusa textilis* was treated using the methods of Example 38 and Comparative Example 18, with the pulping parameters following step (3) of Example 38. After freeze-drying and gold sputtering, the pulps were observed using a scanning electron microscope. The results are as follows: Figure 10 As shown. From Figure 10 It can be seen that the epidermis of bamboo pulp fibers is damaged after enzyme treatment, resulting in more complete fiber separation, a rougher surface, and obvious fibrillation. The resulting microfilaments have a higher fiber binding capacity. Therefore, treatment with the composite enzyme preparation of this invention can not only improve pulp freeness and reduce beating energy consumption, but also enhance paper strength.

[0120] Test Example 5 The chemimechanical pulp of *Cymbidium goeringii* was treated according to the methods of Example 37 and Comparative Example 1, with the beating parameters all following step (3) of Example 37; the chemical pulp of *Cymbidium goeringii* was treated according to the methods of Example 38 and Comparative Example 18, with the beating parameters all following step (3) of Example 38. The beated pulp was then used to form sheets using a small high-speed paper forming machine, with a basis weight of 60 g / m³. 2Each group produced 5-10 sheets. After equilibration in a constant temperature and humidity laboratory at (23±1) ℃ and (50±2)% for 4 hours, the tensile strength of the hand-made sheets was determined using a tensile strength tester according to GB / T 12914—2018 "Determination of Tensile Strength of Paper and Paperboard - Constant Speed ​​Tensile Method (20 mm / min)". The bursting strength of the hand-made sheets was determined using a bursting strength tester according to GB / T 454—2020 "Determination of Bursting Strength of Paper". The tearing strength of the hand-made sheets was determined using a tear tester according to GB / T 455—2002 "Determination of Tear Strength of Paper and Paperboard".

[0121] The results are shown in Table 6. Table 6 shows that both types of *Cymbidium goeringii* pulp showed significantly improved freeness after treatment with the compound enzyme preparation of this invention. The freeness of the mechanical pulping enzyme increased from 50 °SR to 58 °SR, an increase of 16.00%; the freeness of the chemical pulping enzyme increased from 42 °SR to 47 °SR, an increase of approximately 11.90%. This may be because treatment with the compound enzyme preparation of this invention promotes fiber fibrillation. Furthermore, after treatment with the compound enzyme preparation of this invention, the tear index of paper made from the beaten pulp decreased, possibly due to the alteration of fiber length caused by the enzyme treatment; both burst index and tensile index were improved, with the tensile index showing the most significant increase. The tensile index of paper made from Cizhu chemimechanical pulp and Cizhu chemical pulp increased from 37.42 N•m / g to 45.24 N•m / g and from 56.17 N•m / g to 59.35 N•m / g, respectively, representing increases of approximately 20.90% and 5.66%; the burst index increased by 13.59% and 1.26%, respectively. The improvement in burst index and tensile index is likely due to the significant increase in freeness and fiber fibrillation under the same conditions after compound enzyme treatment, which effectively improved the bonding force between fibers and enhanced the bonding strength between fibers, thereby improving the tensile strength of the hand-made sheets.

[0122] Table 6 Physical Strength of Hand-copied Sheets

[0123] Test Example 6 The chemimechanical pulp of *Cymbidium goeringii* was treated according to the methods of Example 37 and Comparative Example 1, with the beating parameters all following step (3) of Example 37; the chemical pulp of *Cymbidium goeringii* was treated according to the methods of Example 38 and Comparative Example 18, with the beating parameters all following step (3) of Example 38. The water retention value of the pulp after beating was determined according to GB / T 29286—2012 "Determination of Water Retention Value of Pulp".

[0124] Weigh approximately 0.10 g of pulp (based on oven-dry pulp weight) and place it in 1000 mL of water. Stir and disperse until evenly dispersed. Then, weigh 250-300 mL of pulp and pour it into a beaker. Analyze the pulp using a fiber morphology analyzer. Analyze approximately 15,000 fibers for each sample. Record all data after testing.

[0125] The results are shown in Tables 7 and 8.

[0126] For bamboo chemimechanical pulp, compared with untreated bamboo chemimechanical pulp, the fiber length decreased by 21.93%, the kink index increased by 49.83%, and the water retention value increased by 11.98% after treatment with the compound enzyme preparation of this invention, while the fiber width did not change significantly. This may be because xylanase and mannanase specifically hydrolyze hemicellulose in the secondary fiber wall, weakening the mechanical strength of the cell wall. Combined with the oxidative breaking effect of LPMO on the cellulose chains, this makes the fibers more prone to axial breakage during beating, resulting in shorter fiber length. The degradation of hemicellulose reduces fiber rigidity, and the oxidation effect of LPMO exposes more hydroxyl groups in the fibers, increasing inter-fiber friction. These factors synergistically promote plastic deformation rather than brittle fracture of the fibers during beating, leading to an increase in the kink index. After enzyme pretreatment, the pulp fibers have more weak points, which are more likely to generate fine molecules during beating. The higher the content of fine fibers, the more hydroxyl groups are exposed, and the greater the probability of interaction with water molecules, thus increasing the fiber water retention value.

[0127] For *Phyllostachys edulis* chemical pulp, the fiber width increased by 1.98%, the kink index increased by 49.13%, and the water retention value increased by 5.64% after enzyme treatment, while the fiber length did not change significantly. The widening of the fibers without a significant change in length may be due to the selective degradation and structural remodeling of the fiber cell walls by enzymes. Xylanase specifically hydrolyzes xylan in the secondary fiber wall, disrupting the hemicellulose network structure and weakening the cell wall rigidity. Ferulic acid esterase decomposes the lignin-carbohydrate complex (LCC), further releasing the binding in the fiber structure and promoting fiber water absorption, swelling, and widening.

[0128] Table 7 Fiber characteristics of bamboo pulp after beating

[0129] Table 8 Fiber characteristics of bamboo pith after beating chemical pulp

[0130] These results indicate that the effects of different compound enzyme preparations on fiber quality vary for bamboo pulp prepared by different processes.

[0131] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A compound enzyme preparation for pulping bamboo pulp, characterized in that, It includes xylanase and polysaccharide monooxygenase, as well as mannanase or ferulic acid esterase.

2. The compound enzyme preparation according to claim 1, characterized in that, The compound enzyme preparation includes xylanase, cleaving polysaccharide monooxygenase and mannanase, and the enzyme activity ratio of xylanase, cleaving polysaccharide monooxygenase and mannanase is (20~40): (6~8): (25~45).

3. The compound enzyme preparation according to claim 2, characterized in that, The enzyme activity ratio of the xylanase, cleaving polysaccharide monooxygenase, and mannanase is 20:10:

35.

4. The compound enzyme preparation according to claim 1, characterized in that, The compound enzyme preparation includes xylanase, cleaving polysaccharide monooxygenase and ferulic acid esterase, wherein the enzyme activity ratio of xylanase, cleaving polysaccharide monooxygenase and ferulic acid esterase is (20~40): (4~8): (10~20).

5. The compound enzyme preparation according to claim 4, characterized in that, The enzyme activity ratio of the xylanase, cleaving polysaccharide monooxygenase, and ferulic acid esterase is 20:20:

4.

6. The application of the compound enzyme preparation according to claim 2 or 3 in the mechanical pulping of bamboo.

7. The application of the compound enzyme preparation according to claim 4 or 5 in the pulping of bamboo chemical pulp.

8. A method for pulping bamboo, characterized in that, Specifically, the following steps are included: S1. Soak the bamboo pulp board in water for at least 4 hours, then tear it into pulp sheets. After the pulp sheets are dispersed evenly into the fiber in the pulp, take them out, spin off the water, break them up, and balance the moisture to obtain a standardized bamboo pulp wet pulp with uniform moisture content. S2. Add water to the standardized bamboo pulp wet slurry to adjust the slurry concentration to 2%~4%, heat to 40~50℃, add the compound enzyme preparation and react for 1.8~2.2 h, then terminate the enzyme reaction; filter, add water to the filter cake obtained by vacuum filtration to adjust the slurry concentration to 8%~12%; S3. The slurry obtained in S2 is pulped with a grinding gap of 0.15~0.2 mm and a grinding speed of 4000~8500 r.

9. The method according to claim 8, characterized in that, The size of the paddle in S1 is 4 cm × 4 cm; and / or In step S2, water is added to the standardized bamboo pulp wet slurry to adjust the slurry concentration to 3%. After heating to 43-47°C, the compound enzyme preparation is added and reacted for 2 hours, then the enzyme reaction is terminated. The mixture is then filtered, and water is added to the resulting filter cake to adjust the slurry concentration to 10%. And / or When the *Cibotium barometz* pulp is a chemiluminescent pulp, the complex enzyme preparation in S2 includes xylanase, a polysaccharide-cleaving monooxygenase, and mannanase. The amount of xylanase added is 20-40 U / g, the amount of the polysaccharide-cleaving monooxygenase added is 6-8 U / g, and the amount of mannanase added is 25-45 U / g; and / or When the *Cibotium barometz* pulp is a chemical pulp, the composite enzyme preparation in S2 includes xylanase, cleaving polysaccharide monooxygenase, and ferulic acid esterase. The amount of xylanase added is 20-40 U / g, the amount of cleaving polysaccharide monooxygenase added is 4-8 U / g, and the amount of ferulic acid esterase added is 10-20 U / g; and / or During the reaction described in S2, stirring should be performed for 4-6 minutes every 7-13 minutes; and / or The method for terminating the enzyme reaction described in S2 is to place the reaction system in a boiling water bath for 5 minutes.

10. The application of the method of claim 8 or 9 in papermaking using bamboo as raw material.

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