Preparation method of papermaking pulp

Abstract

The invention provides a preparation method of papermaking pulp, which comprises the following steps: S100, pretreating plant fibers to obtain raw material fibers; s200, performing soaking treatment on the raw material fibers by adopting a chemical treatment agent to obtain softened fibers; and S300, feeding the softened fibers, the modified nano cellulose and the synthetic fibers into a disc mill for disc milling and pulping to obtain the papermaking pulp, wherein the modified nano cellulose is subjected to carboxylation modification treatment, and the synthetic fiber is polyamide fiber containing a molecular sieve. The invention provides a technical scheme for improving a pulping process by a chemical-mechanical method and considering the waterproof performance and the air permeability of a paper product.

Description

Technical Field

[0001] The present invention relates to the technical field of papermaking, and in particular to a method for preparing papermaking pulp. Background Art

[0002] Paper products such as packaging paperboard and corrugated paper have broad market prospects in the packaging field. Paper products such as packaging paperboard and corrugated paper are usually obtained through chemical mechanical pulping, papermaking, drying, calendering and other processes.

[0003] Chemimechanical pulping is a pulping method that uses chemical pretreatment and mechanical grinding post-treatment. First, a mild pretreatment (impregnation or cooking) is performed with chemicals to remove some hemicellulose in the wood chips, and the lignin is less dissolved or basically not dissolved, but the intercellular layer is softened. Then, the wood chips (or straw chips) are ground and softened by a disc grinder to separate the fibers into pulp.

[0004] The chemical pretreatment of paper pulp is much milder than the cooking process of chemical pulping. It has less delignification effect on the raw materials and less damage to cellulose. Only hemicellulose with lower molecular weight is dissolved. Therefore, the prepared paper pulp generally contains higher lignin and cellulose components and lower hemicellulose components.

[0005] The physical strength of this pulp is between chemical pulp and mechanical pulp, which can make the finished paper have very good stiffness. Its bleaching, hydration and drainage properties are relatively close to those of mechanical pulp.

[0006] The disadvantage of the existing technologies related to paper products such as packaging paperboard and corrugated paper is that it is difficult to balance waterproof and moisture-resistant properties with breathable properties. Summary of the invention

[0007] The present invention aims to solve at least one of the above-mentioned technical problems and provide a technical solution that takes into account both the waterproof performance and the air permeability of paper products by improving the process of chemical mechanical pulping.

[0008] To achieve the above-mentioned object of the present invention, the present invention provides a method for preparing papermaking pulp, the preparation method comprising:

[0009] S100, pretreating plant fibers to obtain raw fiber;

[0010] S200, soaking the raw fiber with a chemical treatment agent to obtain softened fiber;

[0011] S300, sending the softened fiber, modified nanocellulose, and synthetic fiber into a disc refiner for disc refining and beating to obtain the papermaking pulp;

[0012] Wherein, the modified nanocellulose is subjected to carboxyl modification treatment, and the synthetic fiber is a polyamide fiber containing a molecular sieve.

[0013] In any of the above technical solutions, in S200, the mass ratio of chemical treatment agent: raw fiber: water = (0.08-0.12): (12-16): 100.

[0014] In any of the above technical solutions, in S200, the temperature of the immersion treatment is 45° C. to 55° C., and the time of the immersion treatment is 1.5 h to 3 h.

[0015] In any of the above technical solutions, in S300, the mass ratio is softened fiber: modified nanocellulose: synthetic fiber = 100: (6-8): (4-6).

[0016] In any of the above technical solutions, in S300, the pulping concentration of the disc refiner is 20% to 25%, and the beating degree of the papermaking pulp is 35°SR to 45°SR.

[0017] In any of the above technical solutions, the modified nanocellulose is prepared by the following steps:

[0018] S410, uniformly mixing the 4-oxygen-2,2,6,6-tetramethylpiperidin-1-oxygen free radical, the sodium bromide and the nanocellulose in the water at a mass ratio of 4-oxygen-2,2,6,6-tetramethylpiperidin-1-oxygen free radical: sodium bromide: nanocellulose: water = (0.2-0.8): (2-4): (16-18): 100 to obtain a first mixture;

[0019] S420, adding the sodium hypochlorite aqueous solution to the first mixture at a mass ratio of sodium hypochlorite aqueous solution: first mixture = (4-12): 100 while stirring simultaneously, continuing stirring for 6 to 8 hours after the addition is completed, maintaining the pH value of the reaction system at 10-11 by adding sodium hydroxide aqueous solution, filtering, washing, and obtaining the modified nanocellulose.

[0020] In any of the above technical solutions, the synthetic fiber is prepared by the following steps:

[0021] S510, placing the molecular sieve into a mixture of the 1,4-diaminocyclohexane and the water at a mass ratio of 1,4-diaminocyclohexane: molecular sieve: water = (6-8): (15-25): 100, and ultrasonically treating the mixture at a power of 400 W for 30 min to obtain a modified molecular sieve adsorbing the 1,4-diaminocyclohexane;

[0022] S520, first dissolving the N-hydroxysuccinimide trifluoromethanesulfonic acid and the terephthalaldehyde in the water, then dissolving the polyamide in the formic acid, according to the mass ratio of N-hydroxysuccinimide trifluoromethanesulfonic acid: terephthalaldehyde: modified molecular sieve: water: polyamide: formic acid = (0.1-0.2): (2-4): (6-10): (8-10): (40-50): 100, and finally adding the aqueous solution of the N-hydroxysuccinimide trifluoromethanesulfonic acid and the terephthalaldehyde to the mixture of the polyamide and the formic acid, and adding the modified molecular sieve, ultrasonically treating at a power of 800 W for 30 min and simultaneously applying ultraviolet light for 30 min with an 800 W ultraviolet light source of 200 nm to 245 nm to obtain a spinning solution;

[0023] S530, sending the spinning solution into the electrospinning machine, pushing the syringe to electrospin at a speed of 0.1 ml / h to 0.2 ml / h at a voltage of 20 kV, the distance between the needle tip of the syringe and the receiver is 20 cm to 30 cm, and the synthetic fiber is collected by a drum.

[0024] In any of the above technical solutions, the pretreatment in S100 specifically includes: cutting, crushing, screening and washing.

[0025] In any of the above technical solutions, the total added amount of the plant fiber is divided into 100 parts by mass, and the plant fiber in S100 includes: coniferous tree fiber, 40 parts by mass to 50 parts by mass; broad-leaved tree fiber, 30 parts by mass to 40 parts by mass; corn straw fiber, 15 parts by mass to 20 parts by mass.

[0026] In any of the above technical solutions, the total added amount of the chemical treatment agent is divided into 100 parts by mass, and the chemical treatment agent includes: sodium percarbonate, 30 to 35 parts by mass; sodium alkyl sulfonate, 20 to 25 parts by mass; sodium hydroxide, 15 to 20 parts by mass; urea, 15 to 20 parts by mass; sodium silicate, 4 to 6 parts by mass; sodium sulfate, 2 to 4 parts by mass; aluminum phosphate, 1 to 2 parts by mass.

[0027] After adopting the technical scheme of the present invention, the technical effects that can be achieved are as follows: the present invention first pre-treats the plant fiber to obtain raw fiber, then soaks the raw fiber with a chemical treatment agent to obtain softened fiber, and finally feeds the softened fiber, modified nanocellulose, and synthetic fiber into a disc grinder for disc grinding and pulping to obtain the papermaking pulp. Nanocellulose has a high aspect ratio and a network structure. After being added to pulp, it can form "nano bridges" between fibers, significantly enhancing the tensile strength, burst resistance, and folding resistance of paper. It can also fill the gaps between fibers, reduce porosity, and improve the density and surface smoothness of paper. Carboxylated nanocellulose can improve the tensile strength, burst resistance, and folding resistance of paper. The synthetic fiber is a polyamide fiber containing a molecular sieve. The hydrophobicity of polyamide fiber can reduce the strength loss of paper after absorbing water. The porous molecular sieve can make the paper product have better air permeability. Therefore, the paper product obtained by using the pulp of the present invention can take into account both waterproof performance and air permeability. DETAILED DESCRIPTION

[0028] In order to more clearly understand the above-mentioned purpose, features and advantages of the present invention, the present invention is further described in detail below in conjunction with specific embodiments. It should be noted that the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.

[0029] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Therefore, the protection scope of the present invention is not limited to the specific embodiments disclosed below.

[0030] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below.

[0031] The present invention provides a method for preparing papermaking pulp, the preparation method comprising:

[0032] S100, pretreating plant fibers to obtain raw fiber;

[0033] S200, soaking the raw fiber with a chemical treatment agent to obtain softened fiber;

[0034] S300, sending the softened fiber, modified nanocellulose and synthetic fiber into a disc refiner for disc refining and pulping to obtain the papermaking pulp.

[0035] In some embodiments of the present invention, the total added amount of the plant fiber is divided into 100 parts by mass, and the plant fiber in S100 includes: coniferous tree fiber, 40 parts by mass to 50 parts by mass; broad-leaved tree fiber, 30 parts by mass to 40 parts by mass; corn straw fiber, 15 parts by mass to 20 parts by mass.

[0036] Preferably, the total added amount of the plant fibers is divided into 100 parts by mass, and the plant fibers in S100 include: coniferous tree fibers, 45 parts by mass; broadleaf tree fibers, 35 parts by mass; and corn stalk fibers, 20 parts by mass.

[0037] In the papermaking process, softwood fibers and hardwood fibers each have unique roles due to their differences in structure and performance. When used in synergy, paper performance and process economy can be optimized through complementarity. Softwood fibers (such as pine and fir) are generally 2-4 mm in length, with a high aspect ratio, thick fiber cell walls, and excellent mechanical strength (tensile strength, tear strength). Long fibers are easy to form a three-dimensional network structure, providing skeleton support to improve the tensile strength, bursting resistance and tear resistance of the finished paper, and are suitable for high-strength paper types such as packaging paper and paper bag paper. Hardwood fibers (such as eucalyptus and poplar) are generally 0-1.5 mm in length, short and thin. The fiber surface is smooth, the cell wall is thin, and it is easy to be crushed. Short fibers can fill the gaps between long fibers to form a dense structure. Short fibers are easier to pulp, reducing the energy consumption of pulping (the energy consumption required to beat hardwood fibers to the same freeness is lower than that of softwood). Coniferous wood fibers provide skeleton support, while broadleaf wood fibers fill the surface, making the paper have both high strength (such as tensile strength) and good flexibility (such as folding resistance). Broadleaf wood fibers improve smoothness, while coniferous wood fibers reduce hair loss and powder loss. Straw is an agricultural waste that is abundant and renewable. It can reduce dependence on wood and is especially suitable for areas with scarce forest resources. The cost of obtaining straw is lower than that of wood, making it suitable for the production of low value-added paper types (such as corrugated paper and packaging paper). Straw fibers are shorter (0.5-1.5 mm), similar to broadleaf wood fibers, and can fill the gaps between long fibers to improve the tightness and smoothness of paper. Straw fibers are completely degradable and suitable for the production of environmentally friendly packaging materials or disposable paper products.

[0038] In some embodiments of the present invention, the pretreatment in S100 specifically includes: cutting, crushing, screening and washing.

[0039] In some embodiments of the present invention, in S200, by mass ratio, chemical treatment agent: raw fiber: water = (0.08-0.12): (12-16): 100. Preferably, in S200, by mass ratio, chemical treatment agent: raw fiber: water = 0.1: 12: 100. In some embodiments of the present invention, in S200, the soaking treatment temperature is 45° C. to 55° C., and the soaking treatment time is 1.5 h to 3 h.

[0040] In some embodiments of the present invention, in S300, the mass ratio of softened fiber: modified nanocellulose: synthetic fiber = 100: (6-8): (4-6). Preferably, in S300, the mass ratio of softened fiber: modified nanocellulose: synthetic fiber = 100: 6: 6. In S300, the pulping concentration of the disc refiner is 20% to 25%, and the beating degree of the papermaking pulp is 35° SR to 45° SR.

[0041] The chemical treatment agent includes sodium percarbonate, sodium alkyl sulfonate, sodium hydroxide, urea, sodium silicate, sodium sulfate, and aluminum phosphate; the biological enzyme treatment agent includes xylanase, cellulase, pectinase, laccase, and citric acid; and the filler includes triethyl phosphate, molecular sieve, and silicon dioxide.

[0042] In some embodiments of the present invention, the total added amount of the chemical treatment agent is divided into 100 parts by mass, and the chemical treatment agent includes: sodium percarbonate, 30 to 35 parts by mass; sodium alkyl sulfonate, 20 to 25 parts by mass; sodium hydroxide, 15 to 20 parts by mass; urea, 15 to 20 parts by mass; sodium silicate, 4 to 6 parts by mass; sodium sulfate, 2 to 4 parts by mass; aluminum phosphate, 1 to 2 parts by mass.

[0043] Preferably, the total added amount of the chemical treatment agent is divided into 100 parts by mass, and the chemical treatment agent includes: sodium percarbonate, 35 parts by mass; sodium alkyl sulfonate, 20 parts by mass; sodium hydroxide, up to 20 parts by mass; urea, 15 parts by mass; sodium silicate, 5 parts by mass; sodium sulfate, 4 parts by mass; and aluminum phosphate, 1 part by mass.

[0044] Sodium percarbonate, as an oxidant and bleaching agent, can release hydrogen peroxide (H2O2) and sodium carbonate, thereby oxidizing the chromophores in lignin, improving the whiteness of the pulp, and destroying the combination of lignin and cellulose, assisting in fiber separation. The present invention replaces the traditional chlorine-based bleaching agent with sodium percarbonate, which can achieve mild oxidation and reduce fiber damage. Sodium alkyl sulfonate (SodiumAlkylSulfonate) is a surfactant and wetting agent, which can reduce the surface tension of the liquid, promote the penetration of chemicals into the wood chips, and promote fiber dispersion, prevent agglomeration, and improve the uniformity of subsequent mechanical treatment. Sodium hydroxide (SodiumHydroxide), as a strong base, is the core reagent required for lignin removal. Sodium hydroxide can saponify the ester bonds and ether bonds in lignin, destroy its three-dimensional structure, and swell the fiber cell wall, soften the raw materials, and reduce the energy consumption of mechanical pulping. Urea (Urea) can be used as a fiber swelling promoter and reaction aid, which synergizes with alkali to enhance the dissolution of lignin and hemicellulose. In addition, urea decomposes at high temperatures to produce ammonia (NH3), which can adjust local pH and optimize reaction conditions. Sodium silicate (water glass) acts as a pH buffer and dispersant, which can stabilize the alkaline environment and prevent fiber degradation caused by drastic pH fluctuations. It can also be adsorbed on the fiber surface to reduce scaling and improve slurry uniformity. The role of sodium sulfate is to promote the penetration efficiency of chemicals. Aluminum phosphate is adsorbed on the fiber surface to improve the slurry filterability and physical properties of paper. The above raw materials cooperate with each other and work synergistically to destroy the lignin structure and promote chemical penetration and fiber dispersion.

[0045] The modified nanocellulose is subjected to carboxylation modification treatment, and the modified nanocellulose is prepared by the following steps:

[0046] S410, uniformly mixing the 4-oxygen-2,2,6,6-tetramethylpiperidin-1-oxygen free radical, the sodium bromide and the nanocellulose in the water at a mass ratio of 4-oxygen-2,2,6,6-tetramethylpiperidin-1-oxygen free radical: sodium bromide: nanocellulose: water = (0.2-0.8): (2-4): (16-18): 100 to obtain a first mixture;

[0047] S420, adding the sodium hypochlorite aqueous solution to the first mixture at a mass ratio of sodium hypochlorite aqueous solution: first mixture = (4-12): 100 while stirring simultaneously, continuing stirring for 6 to 8 hours after the addition is completed, maintaining the pH value of the reaction system at 10-11 by adding sodium hydroxide aqueous solution, filtering, washing, and obtaining the modified nanocellulose.

[0048] The above steps can introduce carboxyl groups into cellulose. After natural cellulose is oxidized by 4-oxy-2,2,6,6-tetramethylpiperidine-1-oxyl free radical, the C6-aldehyde group of cellulose is catalytically oxidized to generate C6-carboxyl groups. Sodium hypochlorite is used as an oxidant in this process. It first forms sodium hypobromite with sodium bromide, and then sodium hypobromite oxidizes 4-oxy-2,2,6,6-tetramethylpiperidine-1-oxyl free radical into nitrite ions. Nitrite ions oxidize primary alcohol hydroxyl groups into aldehyde intermediates and finally generate carboxyl groups.

[0049] The surface of carboxylated nanocellulose carries a negative charge (-COO-), which forms a stronger hydrogen bond network with the hydroxyl groups (-OH) of pulp fibers. At the same time, it adsorbs positively charged pulp components through electrostatic action, thereby enhancing the bonding strength between fibers and improving the tensile strength, bursting resistance and folding resistance of paper.

[0050] The synthetic fiber is a polyamide fiber containing a molecular sieve, and the synthetic fiber is prepared by the following steps:

[0051] S510, placing the molecular sieve into a mixture of the 1,4-diaminocyclohexane and the water at a mass ratio of 1,4-diaminocyclohexane: molecular sieve: water = (6-8): (15-25): 100, and ultrasonically treating the mixture at a power of 400 W for 30 min to obtain a modified molecular sieve adsorbing the 1,4-diaminocyclohexane;

[0052] S520, first dissolving the N-hydroxysuccinimide trifluoromethanesulfonic acid and the terephthalaldehyde in the water, then dissolving the polyamide in the formic acid, according to the mass ratio of N-hydroxysuccinimide trifluoromethanesulfonic acid: terephthalaldehyde: modified molecular sieve: water: polyamide: formic acid = (0.1-0.2): (2-4): (6-10): (8-10): (40-50): 100, and finally adding the aqueous solution of the N-hydroxysuccinimide trifluoromethanesulfonic acid and the terephthalaldehyde to the mixture of the polyamide and the formic acid, and adding the modified molecular sieve, ultrasonically treating at a power of 800 W for 30 min and simultaneously applying ultraviolet light for 30 min with an 800 W ultraviolet light source of 200 nm to 245 nm to obtain a spinning solution;

[0053] S530, sending the spinning solution into the electrospinning machine, pushing the syringe to electrospin at a speed of 0.1 ml / h to 0.2 ml / h at a voltage of 20 kV, the distance between the needle tip of the syringe and the receiver is 20 cm to 30 cm, and the synthetic fiber is collected by a drum.

[0054] Polyamide fiber has high strength, high modulus and excellent tensile properties, which can make up for the brittle defects of plant fibers and significantly improve the tensile strength, burst resistance and folding resistance of paper. The toughness of polyamide fiber can reduce the risk of tearing of paper under dynamic loads, and is suitable for high-durability packaging materials or industrial paper. The hydrophobicity of polyamide fiber can reduce the strength loss of paper after absorbing water, and is suitable for packaging paper or label paper in humid environments. Porous molecular sieves can make paper products have better air permeability.

[0055] In addition, considering that the surface properties of molecular sieves are quite different from those of polyamide, they are difficult to disperse evenly in polyamide and are prone to agglomeration, resulting in poor homogeneity of polyamide fibers and affecting parameters such as mechanical properties and mechanical properties after pulping and papermaking. Therefore, the present invention modifies the molecular sieves and adjusts the composition and preparation method of the spinning solution.

[0056] The present invention dissolves 1,4-diaminocyclohexane having an amino group in water, immerses a porous molecular sieve therein, and uses ultrasonic treatment to allow the porous molecular sieve to adsorb 1,4-diaminocyclohexane. In the preparation of the spinning solution of polyamide, the present invention uses formic acid as a solvent, and adds N-hydroxysuccinimide trifluoromethanesulfonic acid, terephthalaldehyde and a modified molecular sieve. By subjecting the spinning solution to ultraviolet light, N-hydroxysuccinimide trifluoromethanesulfonic acid can generate free radicals, catalyzing the condensation reaction of 1,4-diaminocyclohexane and terephthalaldehyde on the surface and in the gaps of the molecular sieve, so that the molecular sieve forms new chemical bonds through aldehyde-amine condensation, and is evenly and tightly combined with the polyamide, ensuring that the molecular sieve is evenly dispersed in the polyamide, avoiding agglomeration, and ensuring the mechanical properties and mechanical properties after pulping and papermaking.

[0057] Example 1

[0058] This embodiment provides a modified nanocellulose sample, and the preparation method thereof is as follows.

[0059] S1, mixing the 4-oxygen-2,2,6,6-tetramethylpiperidin-1-oxygen free radical, the sodium bromide and the nanocellulose in the water at a mass ratio of 4-oxygen-2,2,6,6-tetramethylpiperidin-1-oxygen free radical: sodium bromide: nanocellulose: water = 0.4:4:16:100 to obtain a first mixture;

[0060] S2. Add the sodium hypochlorite aqueous solution to the first mixture at a mass ratio of sodium hypochlorite aqueous solution: first mixture = 10:100 while stirring simultaneously. After the addition is completed, continue stirring for 6 hours. Maintain the pH value of the reaction system at 10 by adding sodium hydroxide aqueous solution, filter, wash, and obtain the modified nanocellulose.

[0061] Example 2

[0062] This embodiment provides a synthetic fiber sample 1, and the preparation method thereof is as follows.

[0063] S1. According to the mass ratio of 1,4-diaminocyclohexane: molecular sieve: water = 6:20:100, the molecular sieve is placed in a mixture of the 1,4-diaminocyclohexane and the water, and ultrasonically treated at a power of 400 W for 30 minutes to obtain a modified molecular sieve adsorbed with the 1,4-diaminocyclohexane;

[0064] S2, according to the mass ratio of N-hydroxysuccinimide trifluoromethanesulfonic acid: terephthalaldehyde: modified molecular sieve: water: polyamide: formic acid = 0.2:4:6:10:40:100, first dissolve the N-hydroxysuccinimide trifluoromethanesulfonic acid and the terephthalaldehyde in the water, then dissolve the polyamide in the formic acid, finally add the aqueous solution of the N-hydroxysuccinimide trifluoromethanesulfonic acid and the terephthalaldehyde to the mixture of the polyamide and the formic acid, add the modified molecular sieve, ultrasonically treat at a power of 800 W for 30 minutes and simultaneously apply ultraviolet light for 30 minutes with an 800 W ultraviolet light source of 200 nm to 245 nm to obtain a spinning solution;

[0065] S3, sending the spinning solution into the electrospinning machine, pushing the syringe to electrospin at a speed of 0.15 ml / h at a voltage of 20 kV, the distance between the needle tip of the syringe and the receiver is 20 cm, and the synthetic fiber is collected by a drum.

[0066] Example 3

[0067] This embodiment provides a synthetic fiber sample 2, and the preparation method thereof is as follows.

[0068] S1, molecular sieve: polyamide: formic acid = 6:40:100 mass ratio, dissolving the polyamide in the formic acid, adding the modified molecular sieve, ultrasonically treating at a power of 800 W for 30 min, and simultaneously applying ultraviolet light with an 800 W ultraviolet light source of 200 nm to 245 nm for 30 min, to obtain a spinning solution;

[0069] S2. The spinning solution is fed into an electrospinning machine, and the syringe is pushed to perform electrospinning at a speed of 0.15 ml / h at a voltage of 20 kV. The distance between the needle tip of the syringe and the receiver is 20 cm. The synthetic fiber is collected by a drum.

[0070] Example 4

[0071] This embodiment provides a paper sample 1, and the preparation method thereof is as follows.

[0072] S1. Weigh the materials according to the mass ratio of coniferous tree fiber: broadleaf tree fiber: corn straw fiber = 45:35:20, cut them respectively, crush them into target particle size range, screen them, wash them with water, and mix them to obtain raw fiber;

[0073] S2. Prepare a soaking solution according to the mass ratio of chemical treatment agent: raw fiber: water = 0.1:12:100, soak the raw fiber at a soaking temperature of 48° C. for 2 hours to obtain softened fiber;

[0074] S3, feeding the softened fiber, modified nanocellulose and synthetic fiber into a disc refiner for disc refining and beating according to a mass ratio of softened fiber: modified nanocellulose: synthetic fiber = 100:6:6, to obtain the papermaking pulp;

[0075] S4, after preparing the papermaking pulp, add the wet strength agent or the wet strength agent and the softener, mix them evenly, and then carry out papermaking, pre-drying, sizing (sizing amount 40kg / T), and post-drying to obtain the corrugated paper sample (100g / m 2 ).

[0076] Wherein, the total amount of the chemical treatment agent added is 100 parts by mass, and the chemical treatment agent includes: sodium percarbonate, 35 parts by mass; sodium alkyl sulfonate, 20 parts by mass; sodium hydroxide, 20 parts by mass; urea, 15 parts by mass; sodium silicate, 5 parts by mass; sodium sulfate, 4 parts by mass; aluminum phosphate, 1 part by mass. The modified nanocellulose is obtained by Example 1, and the synthetic fiber is obtained by Example 2.

[0077] Example 5

[0078] This example provides a paper sample 2, the preparation method of which is the same as that of Example 4, except that the synthetic fiber is obtained by Example 3.

[0079] Performance Testing

[0080] The performance test results of paper sample 1-2 are shown in Table 1.

[0081] Table 1

[0082] performance Sample 1 Sample 2 Tear Index <![CDATA[9.6mN m 2 / g]]> <![CDATA[8.8mN m 2 / g]]> Cobb value <![CDATA[28.5g / m 2 ]]> <![CDATA[30.1g / m 2 ]]> Gurley Value 19.2s / 100ml 19.7s / 100ml

[0083] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope defined by the claims.

Claims

1. A method for preparing papermaking pulp, characterized in that: The preparation method comprises: S100, pretreating plant fibers to obtain raw fiber; S200, soaking the raw fiber with a chemical treatment agent to obtain softened fiber; S300, sending the softened fiber, modified nanocellulose, and synthetic fiber into a disc refiner for disc refining and beating to obtain the papermaking pulp; Wherein, the modified nanocellulose is subjected to carboxyl modification treatment, and the synthetic fiber is a polyamide fiber containing a molecular sieve.

2. The preparation method according to claim 1, characterized in that: In S200, the mass ratio of chemical treatment agent: raw fiber: water = (0.08-0.12): (12-16):

100.

3. The preparation method according to claim 1, characterized in that: In S200, the temperature of the immersion treatment is 45°C to 55°C, and the time of the immersion treatment is 1.5h to 3h.

4. The preparation method according to claim 1, characterized in that: In S300, the mass ratio is: softened fiber: modified nanocellulose: synthetic fiber = 100: (6-8): (4-6).

5. The preparation method according to claim 1, characterized in that: In S300, the pulping concentration of the disc refiner is 20% to 25%, and the beating degree of the papermaking pulp is 35°SR to 45°SR.

6. The preparation method according to any one of claims 1 to 5, characterized in that The modified nanocellulose is prepared by the following steps: S410, uniformly mixing the 4-oxygen-2,2,6,6-tetramethylpiperidin-1-oxygen free radical, the sodium bromide and the nanocellulose in the water at a mass ratio of 4-oxygen-2,2,6,6-tetramethylpiperidin-1-oxygen free radical: sodium bromide: nanocellulose: water = (0.2-0.8): (2-4): (16-18): 100 to obtain a first mixture; S420, adding the sodium hypochlorite aqueous solution to the first mixture at a mass ratio of sodium hypochlorite aqueous solution: first mixture = (4-12): 100 while stirring simultaneously, continuing stirring for 6 to 8 hours after the addition is completed, maintaining the pH value of the reaction system at 10-11 by adding sodium hydroxide aqueous solution, filtering, washing, and obtaining the modified nanocellulose.

7. The preparation method according to any one of claims 1 to 5, characterized in that The synthetic fiber is prepared by the following steps: S510, according to 1,4-diaminocyclohexane: The molecular sieve: water = (6-8): (15-25): 100 mass ratio, the molecular sieve is placed in a mixture of the 1,4-diaminocyclohexane and the water, and ultrasonically treated at a power of 400 W for 30 minutes to obtain a modified molecular sieve adsorbed with the 1,4-diaminocyclohexane; S520, according to N-hydroxysuccinimide trifluoromethanesulfonic acid: terephthalaldehyde: modified molecular sieve: water: The mass ratio of polyamide: formic acid is (0.1-0.2): (2-4): (6-10): (8-10): (40-50): 100, firstly dissolving the N-hydroxysuccinimide trifluoromethanesulfonic acid and the terephthalaldehyde in the water, then dissolving the polyamide in the formic acid, finally adding the aqueous solution of the N-hydroxysuccinimide trifluoromethanesulfonic acid and the terephthalaldehyde to the mixture of the polyamide and the formic acid, adding the modified molecular sieve, ultrasonically treating at a power of 800 W for 30 minutes and simultaneously applying ultraviolet light for 30 minutes with an 800 W ultraviolet light source of 200 nm to 245 nm to obtain a spinning solution; S530, sending the spinning solution into the electrospinning machine, pushing the syringe to electrospin at a speed of 0.1 ml / h to 0.2 ml / h at a voltage of 20 kV, the distance between the needle tip of the syringe and the receiver is 20 cm to 30 cm, and the synthetic fiber is collected by a drum.

8. The preparation method according to any one of claims 1 to 5, characterized in that The pretreatment in S100 specifically includes: cutting, crushing, screening and washing.

9. The preparation method according to any one of claims 1 to 5, characterized in that Taking the total added amount of the plant fibers as 100 parts by mass, the plant fibers in S100 include: coniferous tree fibers, 40 parts by mass to 50 parts by mass; broadleaf tree fibers, 30 parts by mass to 40 parts by mass; and corn stalk fibers, 15 parts by mass to 20 parts by mass.

10. The preparation method according to any one of claims 1 to 5, characterized in that: The total added amount of the chemical treatment agent is divided into 100 parts by mass, and the chemical treatment agent includes: sodium percarbonate, 30 to 35 parts by mass; sodium alkyl sulfonate, 20 to 25 parts by mass; sodium hydroxide, 15 to 20 parts by mass; urea, 15 to 20 parts by mass; sodium silicate, 4 to 6 parts by mass; sodium sulfate, 2 to 4 parts by mass; aluminum phosphate, 1 to 2 parts by mass.