Paper product, paper pulp, micro-nano fiber material and preparation method thereof
Micronon cellulose is prepared by combining chemical hydrolysis and high-pressure homogeneity method, which solves the safety risks and environmental pollution problems of enhancers in traditional papermaking processes, and achieves the improvement of paper performance and the optimization of preparation process, which has green and environmental protection and economic advantages.
Patent Information
- Application Number
- CN202510524742.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-24
- Publication Date
- 2025-08-15
AI Technical Summary
The chemical enhancers used in traditional papermaking processes have safety risks and environmental pollution problems, and the preparation method of micro-nanocellulose has problems such as high energy consumption, poor dispersion or high cost.
Micro-nanofibers were prepared by combining chemical hydrolysis and high-pressure homogeneity. The fiber binding capacity was improved through cationic modification treatment, and micro-nanocellulose materials with uniform length and diameter ratios were prepared.
It significantly improves the tensile strength, tear strength and fold resistance of paper, reduces preparation energy consumption and pollution, solves the safety risks of traditional enhancers, and has broad market prospects and economic value.
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Figure CN120486157A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of papermaking pulp, and in particular to a paper product, pulp, micro-nano fiber material and a preparation method thereof. Background Art
[0002] With growing global environmental awareness and the need for improved resource efficiency, the papermaking industry is facing pressure to transform and upgrade. While traditional papermaking processes can meet basic paper production needs, they still require significant improvements in terms of resource consumption, environmental pollution, and product performance. In traditional papermaking, various chemical enhancers are often added to the pulp to improve paper properties such as tensile strength, tear resistance, and folding resistance. Common intra-pulp enhancers include cationic starch, polyacrylamide, and polyvinyl alcohol. These enhancers improve the physical properties of paper by forming hydrogen bonds or physical entanglements with cellulose fibers. Polyacrylamide-based enhancers are more widely used due to their diverse functionality. While synthetic enhancers based primarily on high molecular weight polymers can improve paper strength, their residual monomers or decomposition products may migrate to the paper surface, posing safety risks in contact applications (such as food packaging). They also have poor biodegradability, increasing the environmental burden of long-term use. Furthermore, some cationic enhancers are prone to charge neutralization with anionic impurities in the pulp (such as lignin and hemicellulose), leading to uneven fiber flocculation and affecting paper uniformity and air permeability.
[0003] Micro-nanocellulose (MFC), a new type of reinforcing material, offers advantages unmatched by traditional pulp reinforcements: Its high strength and high modulus significantly improve the tensile strength, tear strength, and folding resistance of paper. Furthermore, MFC is derived from renewable plant fiber resources, its preparation is environmentally friendly, and the product is fully biodegradable. Compared with traditional reinforcements, the use of nanocellulose can significantly reduce the use of chemical reagents and reduce environmental pollution during the papermaking process.
[0004] At present, the preparation process of micro-nanocellulose mainly includes three technical routes: mechanical treatment, chemical pretreatment and biological enzymatic hydrolysis:
[0005] Mechanical methods involve reducing cellulose fibers to nanometer scale through physical means such as high-pressure homogenization, microfluidics, or grinding. This method is simple to operate and low in cost, but the resulting nanocellulose has poor dispersibility and is prone to agglomeration.
[0006] Chemical methods generally include acid hydrolysis and alkaline hydrolysis: Acid hydrolysis uses strong acids (such as sulfuric acid) to hydrolyze cellulose, destroying the hydrogen bond network of cellulose to obtain nanocellulose. Alkaline hydrolysis uses alkaline conditions to destroy the crystalline structure of cellulose, and then further refines the fibers through mechanical treatment. Nanocellulose prepared by chemical methods has good dispersibility, but the use of chemical reagents may have a certain impact on the environment;
[0007] Enzymatic hydrolysis uses cellulases (such as xylanase and cellulase) to selectively degrade cellulose, destroying its microstructure and producing nanocellulose. This method is environmentally friendly and produces nanocellulose with high dispersibility and surface activity, but the production cost is high and the enzyme stability needs further optimization. Summary of the Invention
[0008] In a first aspect, an embodiment of the present application provides a method for preparing a micro-nano fiber material for papermaking, the method comprising:
[0009] Select plant fiber raw materials for chemical hydrolysis;
[0010] The obtained hydrolyzed fibers are subjected to high-pressure homogenization treatment;
[0011] The micro-nanofibers after high-pressure homogenization treatment are cation-modified.
[0012] In some optional embodiments, the step of selecting plant fiber raw materials for chemical hydrolysis includes: crushing the plant fiber raw materials and adding a dilute acid solution, reacting at a first preset temperature for a first preset time, then adding a dilute alkali to adjust the pH to neutral, and squeezing and concentrating to obtain hydrolyzed fiber.
[0013] In some optional embodiments, the plant fiber raw material includes one or more combinations of sulfate coniferous pulp, sulfate broadleaf pulp, wheat straw chemical pulp, and cotton pulp; the dilute acid includes one or more combinations of dilute sulfuric acid, dilute hydrochloric acid, and dilute nitric acid; and the dilute alkali includes one or more combinations of sodium hydroxide and sodium bicarbonate.
[0014] In some optional embodiments, the step of subjecting the obtained hydrolyzed fibers to high-pressure homogenization includes: configuring the hydrolyzed fibers into a fiber suspension of a preset concentration, and then subjecting the suspension to gradient homogenization, to ultimately obtain micro-nanofibers with an aspect ratio of 3000-8000.
[0015] In some optional embodiments, the step of performing gradient homogenization treatment includes: primary defibration: 3-5 cycles at 20-40 MPa; deep stripping: 5-8 cycles at 40-80 MPa; nano-treatment: 2-5 cycles at 80-120 MPa.
[0016] In some optional embodiments, the step of cationically modifying the micro-nanofibers after high-pressure homogenization treatment includes: pretreatment: adjusting the pH of the micro-nanofibers to 8-12 with dilute alkali, and heat-treating at a second preset temperature for a second preset time to activate the fiber hydroxyl groups; cationic modification: adding a cationizing agent to the activated micro-nanofibers and reacting for a third preset time; wherein the cationizing agent includes one or more combinations of 3-chloro-2-hydroxypropyltrimethylammonium chloride, glycidyltrimethylammonium chloride, acryloyloxyethyltrimethylammonium chloride, hexadecyltrimethylammonium bromide, and polydimethyldiallyl ammonium chloride.
[0017] In a second aspect, an embodiment of the present application provides a micro-nano fiber material for papermaking, and the micro-nano fiber material is prepared using the preparation method described in the above embodiment.
[0018] In a third aspect, an embodiment of the present application provides a pulp comprising the micro-nano fiber material described in the above embodiment.
[0019] In some optional embodiments, the pulp also includes wood pulp, 250-350 kg / ton of pulp filler, 5-15 kg / ton of pulp cationic starch, 0-5 kg / ton of pulp glyoxal-modified amphoteric polyacrylamide enhancer, 0.5-2.5 kg / ton of pulp alkenyl succinic anhydride, 0.1-0.3 kg / ton of pulp cationic polyacrylamide, and 1-5 kg / ton of pulp colloidal silica; wherein the added amount of micro-nano fiber material is 2-10 kg / ton of pulp.
[0020] In a fourth aspect, an embodiment of the present application provides a paper product, which is prepared using the pulp described in the above embodiment.
[0021] The preparation method of the micro-nano fiber material for papermaking provided in the embodiment of the present application is different from the conventional pulp reinforcing agent. The fiber raw material used in the preparation method in the embodiment of the present application comes from plants, which has the characteristics of abundant raw materials, health and environmental protection. The present invention innovatively proposes a micro-nano fiber preparation process, which ensures the uniform aspect ratio of the micro-nano fibers while optimizing the preparation process, reducing preparation energy consumption and pollution. Compared with traditional reinforcing agents such as polyacrylamide, the micro-nano fiber-based reinforcing agent prepared by a special treatment process has better performance in improving the mechanical strength of paper such as tensile strength, tear strength, and folding endurance. The micro-nano fiber-based reinforcing agent developed based on the present invention greatly solves the safety risk problem of traditional reinforcing agents, is of great significance to the promotion of high-end paper products, and has broad market prospects. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.
[0023] Figure 1 This is a flow chart of an embodiment of a method for preparing a micro-nano fiber material for papermaking according to the present application;
[0024] Figure 2 It is a schematic diagram of the process of selecting plant fiber raw materials for chemical hydrolysis;
[0025] Figure 3 is a schematic diagram of a process for subjecting the obtained hydrolyzed fibers to a high-pressure homogenization process;
[0026] Figure 4 It is a schematic diagram of the process of cationic modification of micro-nano fibers after high-pressure homogenization treatment;
[0027] Figure 5 It is a schematic block diagram of an embodiment of the papermaking process of the present application. DETAILED DESCRIPTION
[0028] The present application will be further described in detail below in conjunction with the accompanying drawings and examples. It is particularly noted that the following examples are only intended to illustrate the present application and are not intended to limit the scope of the present application. Similarly, the following examples are only some examples of the present application and not all examples. All other examples obtained by those of ordinary skill in the art without creative work are intended to fall within the scope of protection of this application.
[0029] The terms "first", "second" and "third" in the embodiments of the present application are used only for descriptive purposes and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first", "second" and "third" may explicitly or implicitly include at least one of such features. In the description of the present application, "multiple" means at least two, for example, two, three, etc., unless otherwise clearly and specifically defined. All directional indications in the embodiments of the present application (such as up, down, left, right, front, back...) are only used to explain the relative positional relationship, movement, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication also changes accordingly. The terms "including" and "having" in the embodiments of the present application and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but optionally also includes steps or units that are not listed, or optionally also includes other steps or components inherent to these processes, methods, products or devices.
[0030] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.
[0031] The reinforcing effect of micro-nanofibers in paper stems from their unique ability to construct three-dimensional networks: micro-nanofibers with a diameter of 50-100nm can penetrate into the pores between fibers, forming a "fiber-microfiber" composite interface through van der Waals forces and hydrogen bonds, thereby improving the strength of the paper; studies have shown that the aspect ratio of micro-nanofibers is significantly higher than that of ordinary pulp fibers, and they can effectively disperse stress when the paper is loaded, thereby improving the mechanical properties of the paper.
[0032] Conventional micro-nanofiber preparation methods, such as mechanical methods, can directly separate fibers, but have defects such as high energy consumption and uncontrollable fiber length; although chemical methods can improve fiber dissociation efficiency, they are prone to introduce chlorine-containing by-products and destroy fiber crystallinity; although the bioenzymatic method (cellulase treatment) has green characteristics, it has technical bottlenecks such as long reaction cycle and easy inactivation of cellulase, as well as preparation cost defects.
[0033] In view of this, the present invention provides a method for preparing micro-nano fiber materials for papermaking. Figure 1 , Figure 11 is a flow chart of an embodiment of a method for preparing micro-nano fiber materials for papermaking of the present application, and the preparation method includes but is not limited to the following steps.
[0034] Step S100: Select plant fiber raw materials for chemical hydrolysis.
[0035] See also Figure 2 , Figure 2 The present invention is a schematic flow chart of selecting plant fiber raw materials for chemical hydrolysis, in which the following steps may be specifically included.
[0036] Step S110: crushing the plant fiber raw material and adding a dilute acid solution.
[0037] In this step, a plant fiber raw material may be selected, crushed and passed through a 50-mesh sieve, and then a 2-10 wt% dilute acid solution may be added thereto. The plant fiber raw material may include one or a combination of softwood sulfate pulp, hardwood sulfate pulp, wheat straw chemical pulp, and cotton pulp; and the dilute acid may include one or a combination of dilute sulfuric acid, dilute hydrochloric acid, and dilute nitric acid.
[0038] Step S120 , reacting at a first preset temperature for a first preset time.
[0039] In step S120, the reaction may be carried out at 80-110°C for 60-180 minutes.
[0040] Step S130: adding dilute alkali to adjust the pH to neutral.
[0041] The dilute alkali includes one or a combination of sodium hydroxide and sodium bicarbonate.
[0042] Step S140: performing extrusion and concentration to obtain hydrolyzed fibers.
[0043] Please continue reading Figure 1 The preparation method in this embodiment further includes step S200, wherein the obtained hydrolyzed fiber is subjected to high-pressure homogenization treatment.
[0044] See also Figure 3 , Figure 3 This is a schematic diagram of a process for subjecting the obtained hydrolyzed fibers to high-pressure homogenization. This step may specifically include the following steps.
[0045] Step S210: preparing the hydrolyzed fibers into a fiber suspension of a preset concentration.
[0046] In this step, the hydrolyzed fibers may be prepared into a fiber suspension with a concentration of 0.5-1.5 wt%.
[0047] Step S220 , performing gradient homogenization treatment to finally obtain micro-nano fibers with an aspect ratio of 3000-8000.
[0048] In step S220, the step of performing gradient homogenization treatment may include: primary defibration: 3-5 cycles at 20-40 MPa; deep stripping: 5-8 cycles at 40-80 MPa; nano-treatment: 2-5 cycles at 80-120 MPa.
[0049] Please continue reading Figure 1 The preparation method in this embodiment further includes step S300 of cationically modifying the micro-nanofibers after high-pressure homogenization treatment.
[0050] See also Figure 4 , Figure 4 This is a schematic diagram of a process for cationic modification of micro-nano fibers after high-pressure homogenization treatment. This step may specifically include the following steps.
[0051] Step S310, pretreatment: adjusting the pH of the micro-nano fibers to 8-12 with a dilute alkali, and preserving the micro-nano fibers at a second preset temperature for a second preset time to activate the fiber hydroxyl groups.
[0052] In this step, the pH of the micro-nano fibers can be adjusted to 8-12 with a dilute alkali (including one or a combination of sodium hydroxide and sodium bicarbonate), and then heat-treated at 50-80° C. for 20-60 minutes.
[0053] Step S320, cationic modification: adding a cationic agent to the activated micro-nanofibers and reacting for a third preset time.
[0054] In this step, 5-15 wt% of a cationizing agent is added to the activated micro-nanofibers and allowed to react for 2-6 hours to produce a modified micro-nanofiber material having high reactivity and a high fiber cationic charge density. The cationizing agent may include one or more of 3-chloro-2-hydroxypropyltrimethylammonium chloride, glycidyltrimethylammonium chloride, acryloyloxyethyltrimethylammonium chloride, hexadecyltrimethylammonium bromide, and polydimethyldiallylammonium chloride.
[0055] The method for preparing micro-nano fiber materials for papermaking in the embodiments of the present application innovatively develops a two-step method for preparing micro-nano fibers, namely a combination of chemical hydrolysis and high-pressure homogenization, which breaks through the technical bottlenecks of high energy consumption, severe fiber damage, and insufficient homogenization in the traditional single method for preparing micro-nano cellulose. Chemical hydrolysis pretreatment preferentially breaks the non-crystalline region of cellulose and the hemicellulose connection, significantly reducing the strength of hydrogen bonds between fibers, and reducing the pressure required for subsequent high-pressure homogenization by 40%-60%; the cavitation effect and shear force generated by the high-pressure homogenization process act precisely on the pre-depolymerization area, achieving longitudinal peeling of the fibers rather than transverse breakage, and obtaining high-quality micro-nano fibers. New micro-nano fiber modification method: through surface charge modification, cationic groups are introduced into micro-nano fibers to enhance the binding ability of micro-nano cellulose with pulp fibers and fillers. This is not only beneficial to the retention of micro-nano fibers in the papermaking system, but also more beneficial to the improvement of paper strength.
[0056] The preparation method of the micro-nano fiber material for papermaking provided in the embodiment of the present application is different from the conventional pulp reinforcing additives. The fiber raw materials used in the preparation method in the embodiment of the present application come from plants, which have the characteristics of abundant raw materials, health and environmental protection; the present invention innovatively proposes a micro-nano fiber preparation process, which ensures the uniform aspect ratio of the micro-nano fibers while optimizing the preparation process, reducing preparation energy consumption and pollution; compared with traditional reinforcing agents such as polyacrylamide, the micro-nano fiber-based reinforcing agent prepared by a special treatment process has better performance in improving the mechanical strength of paper such as tensile strength, tear strength, and folding resistance. The micro-nano fiber-based reinforcing agent developed based on the present invention greatly solves the safety risk problem of traditional reinforcing agents, is of great significance to the promotion of high-end paper products, and has broad market prospects. The micro-nano fiber material in the embodiment of the present application not only has better performance in improving paper strength, but also has the advantages of being green, environmentally friendly, energy-saving and consumption-reducing, and has broad economic value and social value.
[0057] In addition, the embodiment of the present application also provides an application of micro-nano fiber materials, that is, application in pulp. Among them, the ingredients of the pulp may include: 0-100 parts of bleached sulfate softwood pulp, beating degree 30-50°SR; 0-100 parts of bleached sulfate broadleaf pulp, beating degree 30-50°SR; 0-10 parts of bleached chemical thermomechanical pulp, beating degree 30-50°SR; add 2-10kg / ton of pulp micro-nano fiber-based reinforcing agent at the outlet of the mixing pulp tank, mix evenly in a static mixer, add filler 250-350kg / ton of pulp, cationic starch 5-15kg / ton of pulp, glyoxal modified amphoteric polyacrylamide reinforcing agent 0-5kg / ton of pulp, alkenyl succinic anhydride (ASA) 0.5-2.5kg / ton of pulp, cationic polyacrylamide (CPAM) 0.1-0.3kg / ton of pulp, colloidal silica 1-5kg / ton of pulp, and control the paper weight to 160g / m2 .
[0058] See also Figure 5 , Figure 5 This is a schematic block diagram of an embodiment of the papermaking process of the present application, wherein the micro-nano fiber material 81 in this embodiment can be added between the mixing pulp tank 82 and the pulping tank 83. Other papermaking processes are within the scope of understanding of those skilled in the art and will not be described here.
[0059] Several specific embodiments and comparative embodiments are introduced below to illustrate the effects.
[0060] Comparative Example 1
[0061] Commercially available micro-nanofibers;
[0062] Comparative Example 2
[0063] The pulp was prepared by mixing 10 parts of bleached softwood sulfate pulp with a beating degree of 40°SR; 70 parts of bleached hardwood sulfate pulp with a beating degree of 45°SR; and 20 parts of bleached chemical thermomechanical pulp with a beating degree of 45°SR. The pulp was then added with 250 kg of filler per ton of pulp, 8 kg of cationic starch per ton of pulp, 5 kg of glyoxal-modified amphoteric polyacrylamide enhancer per ton of pulp, 0.9 kg of alkenyl succinic anhydride (ASA) per ton of pulp, 0.2 kg of cationic polyacrylamide (CPAM) per ton of pulp, and 3 kg of colloidal silica per ton of pulp. The paper weight was 160 g / m 2 .
[0064] Comparative Example 3
[0065] The bleached softwood sulfate pulp (10 parts) and the beating degree (40°SR) were controlled; the bleached hardwood sulfate pulp (70 parts) and the beating degree (45°SR) were controlled; the bleached chemical thermomechanical pulp (20 parts) and the beating degree (45°SR) were controlled; 5 kg / ton of commercially available micro-nano fibers were added at the outlet of the mixing tank; 250 kg / ton of filler, 8 kg / ton of cationic starch, 0.9 kg / ton of alkenyl succinic anhydride (ASA), 0.2 kg / ton of cationic polyacrylamide (CPAM), and 3 kg / ton of colloidal silica were added; and the paper weight was 160 g / m 2 .
[0066] Example 1
[0067] Kraft softwood pulp was pulverized and passed through a 50-mesh sieve. An 8wt% dilute sulfuric acid solution was added and reacted at 85°C for 120 minutes. The pH was then adjusted to neutral with dilute NaOH, followed by extrusion and concentration to produce hydrolyzed fibers. The hydrolyzed fibers were then prepared into a 1.0wt% fiber suspension and subjected to a gradient homogenization process: a. Primary defibration: three cycles at 20 MPa; b. Deep stripping: six cycles at 60 MPa; c. Nanofiberization: three cycles at 90 MPa. The resulting fibers had an aspect ratio of 4100.
[0068] The micro-nano fibers were treated with diluted NaOH to a pH of 9 and then incubated at 65°C for 30 minutes to activate the fiber hydroxyl groups. 8 wt% acryloyloxyethyltrimethylammonium chloride was added to the activated micro-nano fibers and allowed to react for 3 hours to produce a modified micro-nano fiber-based reinforcing agent.
[0069] The following steps were used to control the mixing of 10 parts of bleached softwood sulfate pulp with a beating degree of 40°SR; 70 parts of bleached hardwood sulfate pulp with a beating degree of 45°SR; and 20 parts of bleached chemical thermomechanical pulp with a beating degree of 45°SR. 5 kg / ton of modified micro-nano fiber-based reinforcing agent was added to the outlet of the mixing tank. 250 kg / ton of filler, 8 kg / ton of cationic starch, 0.9 kg / ton of alkenyl succinic anhydride (ASA), 0.2 kg / ton of cationic polyacrylamide (CPAM), and 3 kg / ton of colloidal silica were also added. The paper weight was 160 g / m 2 .
[0070] Example 2
[0071] Kraft softwood pulp was pulverized and passed through a 50-mesh sieve. A 10 wt% dilute sulfuric acid solution was added and reacted at 100°C for 120 minutes. The pH was then adjusted to neutral with dilute NaOH, followed by extrusion and concentration to produce hydrolyzed fibers. The hydrolyzed fibers were then prepared into a 1.0 wt% fiber suspension and subjected to a gradient homogenization process: a. Primary defibration: three cycles at 30 MPa; b. Deep defiberization: six cycles at 70 MPa; c. Nanofiberization: five cycles at 100 MPa. The resulting fibers had an aspect ratio of 6500.
[0072] The micro-nano fibers were adjusted to pH 9 with dilute NaOH and treated at 80°C for 50 minutes to activate the fiber hydroxyl groups. 8 wt% 3-chloro-2-hydroxypropyltrimethylammonium chloride was added to the activated micro-nano fibers and allowed to react for 4 hours to produce a modified micro-nano fiber-based reinforcing agent.
[0073] The following steps were used to control the mixing of 10 parts of bleached softwood sulfate pulp with a beating degree of 40°SR; 70 parts of bleached hardwood sulfate pulp with a beating degree of 45°SR; and 20 parts of bleached chemical thermomechanical pulp with a beating degree of 45°SR. 5 kg / ton of modified micro-nano fiber-based reinforcing agent was added to the outlet of the mixing tank. 250 kg / ton of filler, 8 kg / ton of cationic starch, 0.9 kg / ton of alkenyl succinic anhydride (ASA), 0.2 kg / ton of cationic polyacrylamide (CPAM), and 3 kg / ton of colloidal silica were also added. The paper weight was 160 g / m 2 .
[0074] Example 3
[0075] Kraft softwood pulp was pulverized and passed through a 50-mesh sieve. A 10 wt% dilute sulfuric acid solution was added and reacted at 100°C for 120 minutes. The pH was then adjusted to neutral with dilute NaOH, followed by extrusion and concentration to produce hydrolyzed fibers. The hydrolyzed fibers were then prepared into a 1.0 wt% fiber suspension and subjected to a gradient homogenization process: a. Primary defibration: three cycles at 30 MPa; b. Deep defiberization: six cycles at 70 MPa; c. Nanofiberization: five cycles at 100 MPa. The resulting fibers had an aspect ratio of 6500.
[0076] The micro-nano fibers were adjusted to pH 9 with dilute NaOH and treated at 80°C for 50 minutes to activate the fiber hydroxyl groups. 8 wt% 3-chloro-2-hydroxypropyltrimethylammonium chloride was added to the activated micro-nano fibers and allowed to react for 4 hours to produce a modified micro-nano fiber-based reinforcing agent.
[0077] Control the bleached softwood sulfate pulp to 5 parts and the beating degree to 40°SR; bleached hardwood sulfate pulp to 65 parts and the beating degree to 45°SR; bleached chemical thermomechanical pulp to 35 parts and the beating degree to 45°SR; add 5kg / ton of modified micro-nano fiber-based reinforcing agent at the outlet of the mixed pulp tank, add 330kg / ton of filler, 8kg / ton of cationic starch, 0.9kg / ton of alkenyl succinic anhydride (ASA), 0.2kg / ton of cationic polyacrylamide (CPAM), and 3kg / ton of colloidal silica, and the paper weight is 160g / m 2 .
[0078] The main tested physical properties of each example and the comparison are shown in the following table.
[0079]
[0080]
[0081] The results show that the preparation method of the micro-nano fiber material in the embodiments of this application and its reinforcing effect in paper: the micro-nano fibers produced by the combination of chemical hydrolysis + high-pressure homogenization have a better aspect ratio than commercially available products and stable quality; after cationic modification, the obtained micro-nano fiber-based reinforcing agent has a larger positive charge and a stronger ability to bind with pulp fibers; adding it to the wet end system of the pulp to replace the polyacrylamide reinforcing agent and the commercially available micro-nano fiber product in equal amounts has the best reinforcing effect on paper; after increasing the mechanical pulp ratio and ash ratio, the paper strength is still slightly better than that of using polyacrylamide reinforcing agents and commercially available micro-nano fiber products, and has strong economic and social value.
[0082] The micro-nano fiber material in the embodiment of the present application is applied to paper pulp. In order to ensure the full combination of micro-nano fibers and pulp fibers to the greatest extent, it is designed to be added during the wet end process of the pulp: the micro-nano fibers are combined with pulp fibers and fillers before other additives to avoid affecting the combination of micro-nano fibers; it is designed to add micro-nano fiber-based reinforcing agents to paper with high mechanical pulp ratio and high ash ratio, which not only improves the strength of the paper, but also further increases the application limit of mechanical pulp and ash ratio, fully reflecting the economic value and social value of micro-nano fibers.
[0083] The above descriptions are only some embodiments of the present application and do not limit the scope of protection of the present application. Any equivalent device or equivalent process transformation made using the contents of the description and drawings of this application, or directly or indirectly applied in other related technical fields, are also included in the scope of patent protection of this application.
Claims
1. A method for preparing micro-nano fiber materials for papermaking, characterized in that: The preparation method comprises: Select plant fiber raw materials for chemical hydrolysis; The obtained hydrolyzed fibers are subjected to high-pressure homogenization treatment; The micro-nanofibers after high-pressure homogenization treatment are cation-modified.
2. The preparation method according to claim 1, characterized in that The step of selecting plant fiber raw materials for chemical hydrolysis includes: crushing the plant fiber raw materials and adding a dilute acid solution, reacting at a first preset temperature for a first preset time, then adding a dilute alkali to adjust the pH to neutral, and squeezing and concentrating to obtain hydrolyzed fiber.
3. The preparation method according to claim 2, characterized in that The plant fiber raw material includes one or a combination of sulfate coniferous wood pulp, sulfate broadleaf wood pulp, wheat straw chemical pulp, and cotton pulp; the dilute acid includes one or a combination of dilute sulfuric acid, dilute hydrochloric acid, and dilute nitric acid; and the dilute alkali includes one or a combination of sodium hydroxide and sodium bicarbonate.
4. The preparation method according to claim 1, characterized in that The step of subjecting the obtained hydrolyzed fibers to high-pressure homogenization treatment includes: configuring the hydrolyzed fibers into a fiber suspension of a preset concentration, and then subjecting the suspension to gradient homogenization treatment, to ultimately obtain micro-nano fibers with an aspect ratio of 3000-8000.
5. The preparation method according to claim 4, characterized in that The steps of performing gradient homogenization treatment include: primary defibration: 3-5 cycles at 20-40 MPa; deep stripping: 5-8 cycles at 40-80 MPa; and nano-treatment: 2-5 cycles at 80-120 MPa.
6. The preparation method according to claim 1, characterized in that The step of cationic modification of the micro-nano fibers after high-pressure homogenization treatment The pretreatment includes: adjusting the pH of the micro-nano fibers to 8-12 with a dilute alkali, and heat-treating at a second preset temperature for a second preset time to activate the fiber hydroxyl groups; Modification: adding a cationizing agent to the activated micro-nanofibers and reacting for a third preset time; wherein the cationizing agent includes one or more combinations of 3-chloro-2-hydroxypropyltrimethylammonium chloride, glycidyltrimethylammonium chloride, acryloyloxyethyltrimethylammonium chloride, hexadecyltrimethylammonium bromide, and polydimethyldiallyl ammonium chloride.
7. A micro-nano fiber material for papermaking, characterized in that: The micro-nano fiber material is prepared by the preparation method according to any one of claims 1 to 6.
8. A pulp, characterized in that: The pulp comprises the micro-nano fiber material according to claim 7.
9. The pulp according to claim 8, characterized in that The paper pulp also includes wood pulp, 250-350 kg / ton of filler, 5-15 kg / ton of cationic starch, 0-5 kg / ton of glyoxal-modified amphoteric polyacrylamide enhancer, 0.5-2.5 kg / ton of alkenyl succinic anhydride, 0.1-0.3 kg / ton of cationic polyacrylamide, and 1-5 kg / ton of colloidal silicon dioxide; wherein the added amount of micro-nano fiber material is 2-10 kg / ton of pulp.
10. A paper product, characterized in that: The paper product is prepared using the pulp according to claim 8 or 9.