Paper, pulp and method for producing the same

Abstract

The application provides a paper product, a paper pulp and a preparation method thereof; the preparation method of the paper pulp comprises the following steps: spraying a cationic dry strength agent on the surface of an alkaline hydrogen peroxide mechanical pulp semi-dry pulp; adding polyaluminum chloride into pulp water; mixing the alkaline hydrogen peroxide mechanical pulp semi-dry pulp, on the surface of which the cationic dry strength agent is sprayed, with the pulp water, in which the polyaluminum chloride is added, to carry out pulp beating; performing grinding on the pulp after the pulp beating; and adding an amphoteric dry strength agent into the pulp after the grinding. The preparation method of the paper pulp provided in the application improves the comprehensive strength of APMP (alkaline hydrogen peroxide mechanical pulp) semi-dry pulp through a series of pretreatments, including fiber charge modification and coating enhancement, during the process of pulp beating of the APMP semi-dry pulp to pulp, so that the proportion of APMP pulp in paper is increased or the ash content of paper is increased, thereby reducing the consumption of chemical pulp fibers and saving costs.

Description

Technical Field

[0001] This application relates to the technical field of papermaking, specifically to a paper product, pulp, and a method for preparing the same. Background Technology

[0002] With the increasing severity of global climate change and environmental problems, governments worldwide are strengthening environmental regulations and carbon emission controls. Against this backdrop, achieving carbon peaking and carbon neutrality has become a global consensus and goal. Carbon peaking means that a country or region's carbon dioxide emissions reach a peak within a certain period and then cease to increase, while carbon neutrality involves offsetting carbon dioxide emissions through various measures to achieve net zero emissions. In this context, the use of high-yield pulp as a raw material for producing paper and other cellulose-based products is gradually becoming an industry trend. High-yield pulp is a process that extracts cellulose fibers from wood using purely mechanical or chemimechanical methods. Compared to traditional chemical or mechanical pulp, it has a higher fiber extraction rate, lower energy consumption, and fewer chemical additives used, thus reducing carbon emissions and environmental pollution during production. Several advantages of using high-yield pulp in terms of environmental protection and carbon peaking include: 1. High fiber extraction rate: High-yield pulp has a higher fiber extraction rate than traditional processes, meaning that more paper or other cellulose products can be produced from the same amount of wood, reducing the demand for raw materials. 2. Low Energy Consumption Production: Compared to traditional chemical pulp, high-yield pulp production consumes less energy, helping to reduce overall energy consumption and carbon emissions. 3. Reduced Chemical Additives: High-yield pulp production uses fewer chemical additives, reducing chemical pollution and lowering the cost and difficulty of wastewater treatment. 4. Circular Economy: Byproducts generated during high-yield pulp production, such as lignin, can be recycled and used to produce biofuels and chemical raw materials, promoting the development of a circular economy. 5. Policy Support: To promote environmental protection and achieve carbon peaking goals, the government has introduced a series of policies and incentives to support the research and application of environmentally friendly production processes such as high-yield pulp. 6. Market Demand: As consumers become more aware of environmental protection and sustainable development, the market demand for environmentally friendly paper and cellulose products is constantly growing. Using high-yield pulp can meet this market demand. Cost Reduction: The cost per ton of high-yield pulp is far lower than that of chemical pulp. Therefore, in a highly competitive market environment, paper companies can use high-yield pulp to balance production costs, cope with fierce market competition, and maintain profitability.

[0003] Although the use of mechanical pulp has many benefits for environmental protection and cost control, the low physical strength and low brightness of mechanical pulps such as APMP are the biggest problems limiting their application in paper. Summary of the Invention

[0004] The first aspect of this application provides a method for preparing pulp, the method comprising:

[0005] Spray a cationic dry strength agent onto the semi-dry surface of the alkaline hydrogen peroxide mechanical pulp;

[0006] Add polyaluminum chloride to the slurry water;

[0007] The semi-dry slurry of alkaline hydrogen peroxide mechanical slurry with a surface sprayed with a cationic dry strength agent is mixed with slurry water containing polyaluminum chloride for slurry spreading.

[0008] The pulp after it has been loosened is then refined;

[0009] Add an amphoteric dry strength agent to the refined pulp.

[0010] In some embodiments, the cationic dry strength agent is a cationic polyacrylamide polymer; the molecular weight of the cationic polyacrylamide polymer is 6 million to 12 million.

[0011] In some embodiments, the concentration of the cationic dry strength agent is 0.1-1.0%.

[0012] In some embodiments, the amount of cationic dry strength agent added is 3-20 kg / ton of pulp.

[0013] In some embodiments, in the step of adding polyaluminum chloride to the pulp water, the amount of polyaluminum chloride used is 1000-20000 ppm relative to the oven-dry amount of the alkaline hydrogen peroxide mechanical pulp.

[0014] In some embodiments, the amount of polyaluminum chloride used is 2000-3000 ppm relative to the oven-dry amount of the alkaline hydrogen peroxide mechanical slurry.

[0015] In some embodiments, in the step of adding an amphoteric dry strength agent to the refined pulp, the amphoteric dry strength agent is amphoteric polyacrylamide, and the molecular weight of the amphoteric polyacrylamide is between 6 million and 12 million.

[0016] In some embodiments, the amount of amphoteric polyacrylamide used is 10-60 kg / ton of slurry.

[0017] Secondly, embodiments of this application provide a pulp, which is prepared using the preparation method described in the above embodiments.

[0018] Thirdly, this application provides a paper product, which is obtained by preparing the pulp as described in the above embodiments.

[0019] The pulp preparation method provided in this application improves the overall strength of APMP (alkaline hydrogen peroxide mechanical pulp) by a series of pretreatments during the process of APMP semi-dry pulp dispersal to pulping, including fiber charge modification and coating reinforcement. This increases the proportion of APMP pulp in the paper or increases the ash content of the paper, thereby reducing the consumption of chemical pulp fibers and saving costs. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic flowchart of an embodiment of the pulp preparation method of this application;

[0022] Figure 2 This is a flowchart illustrating the control group example;

[0023] Figure 3 This is a flowchart illustrating an embodiment of a conventional coating process.

[0024] Figure 4 This is a flowchart illustrating an example of adding and optimizing PAC.

[0025] Figure 5 This is a schematic diagram of the encapsulation scheme according to an embodiment of this application. Detailed Implementation

[0026] The present application will now be described in further detail with reference to the accompanying drawings and embodiments. It should be particularly noted that the following embodiments are for illustrative purposes only and do not limit the scope of the application. Similarly, the following embodiments are only some, not all, embodiments of the present application, and all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of the present application.

[0027] The terms "first," "second," and "third" used in the embodiments of this application are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first," "second," or "third" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified. All directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of this application are only used to explain the relative positional relationships and movement of components in a specific posture (as shown in the figures). If the specific posture changes, the directional indication will also change accordingly. The terms "comprising" and "having," and any variations thereof, in the embodiments of this application are intended to cover non-exclusive inclusion. 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 may optionally include steps or units not listed, or may optionally include other steps or components inherent to these processes, methods, products, or devices.

[0028] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0029] The technical solution provided in this application mainly involves a pretreatment and multi-layer coating process for APMP (alkaline hydrogen peroxide mechanical pulp) semi-dry pulp. This process enhances the bonding strength of the mechanical pulp while minimizing the adverse effects of increased APMP usage on paper strength, thereby reducing the cost per ton of paper while meeting paper quality requirements. This approach not only reduces raw material costs but also increases the proportion of high-yield pulp in the paper pulp structure, aligning with the trend towards green and environmentally friendly papermaking.

[0030] Please see Figure 1 , Figure 1 This is a schematic flowchart of an embodiment of the pulp preparation method of this application, which includes, but is not limited to, the following steps.

[0031] Step S100: Spray a cationic dry strength agent onto the semi-dry surface of the alkaline hydrogen peroxide mechanical slurry.

[0032] Before the APMP (Alkaline Hydrogen Peroxide Mechanical Pulp) semi-dry pulp is fed into the pulper for spreading, a cationic dry strength agent is added to the fiber surface by spraying. The cationic dry strength agent is a CPAM (Polyacrylamide) positive polymer with a molecular weight of 6 million to 12 million, such as 6 million, 6.5 million, 7 million, 8 million, 10 million, and 12 million. In this embodiment, 6-8 million units can be selected; the concentration of the cationic dry strength agent can be 0.1-1.0%, and the specific concentration can be 0.1%, 0.2%, 0.21%, 0.32%, 0.4%, 0.5%, 0.7%, 0.9%, 1.0%, etc. In this embodiment, it can be 0.2-0.4%; the dosage of the cationic dry strength agent is 3-20 kg / ton of pulp, for example, 3 kg / ton of pulp, 3.8 kg / ton of pulp, 4.7 kg / ton of pulp, 5 kg / ton of pulp, 7 kg / ton of pulp, 9 kg / ton of pulp, 13 kg / ton of pulp, 16 kg / ton of pulp, 18 kg / ton of pulp, 20 kg / ton of pulp, etc. In this embodiment, 5-6 kg / ton of pulp can be selected.

[0033] Please continue reading. Figure 1 The preparation method in this embodiment also includes step S200, which involves adding polyaluminum chloride to the slurry water.

[0034] In step S200, PAC (polyaluminum chloride) is added to the APMP slurry in advance. Through charge adsorption and flocculation, the anionic waste in the APMP slurry is treated, reducing the adverse effects of anionic waste on the adsorption and coating of the dry strength agent and APMP fibers. The amount of PAC relative to the APMP slurry is 1000-20000 ppm (octane-dry to oven-dry), specifically 1000 ppm, 2000 ppm, 2300 ppm, 3400 ppm, 5000 ppm, 8700 ppm, 10000 ppm, 1200 ppm, 14000 ppm, 15000 ppm, 15600 ppm, 18000 ppm, 20000 ppm, etc. In this embodiment, it can be 2000-3000 ppm.

[0035] Please continue reading. Figure 1 The preparation method in this embodiment also includes step S300, which involves mixing the alkaline hydrogen peroxide mechanical slurry semi-dry slurry with a cationic dry strength agent sprayed on the surface with slurry water containing polyaluminum chloride to perform slurry spreading.

[0036] Step S400: Refining the pulp after it has been loosened.

[0037] Step S500: Add an amphoteric dry strength agent to the refined pulp.

[0038] An amphoteric dry strength agent is added after APMP pulping. Through the electrostatic adsorption and adhesion between the amphoteric dry strength agent and APMP fibers, the APMP fibers are coated, thereby increasing the bonding strength between APMP and other chemical fibers during subsequent papermaking. The amphoteric dry strength agent can be amphoteric polyacrylamide with a molecular weight of approximately 6 million to 12 million, such as 6 million, 6.5 million, 7 million, 8 million, 10 million, and 12 million. In this embodiment, a molecular weight of 8-9 million is specifically selected. The dosage of the amphoteric dry strength agent is 10-60 kg / ton of pulp (octane-dry to dope), such as 10 kg / ton of pulp, 10.9 kg / ton of pulp, 13 kg / ton of pulp, 15 kg / ton of pulp, 20 kg / ton of pulp, 23 kg / ton of pulp, 34 kg / ton of pulp, 45 kg / ton of pulp, 50 kg / ton of pulp, and 60 kg / ton of pulp. In this embodiment, it is 40-60 kg.

[0039] The pulp preparation method in this application has the following characteristics: ① Cationic dry strength agent (CPAM) is added in the semi-dry state of APMP pulp. Through atomized spraying, the dry strength agent is uniformly adsorbed onto the surface via adsorption, achieving a uniform coating of the APMP fiber surface even with a small amount added. ② PAC is added in the APMP pulp dispersing water, allowing PAC to first treat the anionic waste in the clarified water, and then further treat the anionic waste in the APMP pulp during the APMP dispersing process, maximizing the treatment effect. With the addition of PAC in this method, the PCD of 4% APMP pulp after dispersing is -200 to -300 μeq / L (while adding PAC after APMP dispersing results in a PCD of approximately -500 to -600 μeq / L for 4% APMP pulp). ③ A multi-layer coating scheme, employing cationic coating followed by amphoteric coating, allows dry strength agents with different charges to better coat the fiber surface, improving adhesion. Simultaneously, it increases the retention rate of the dry strength agent in the paper during high-vacuum suction and pressing processes on the paper machine, thereby enhancing the reinforcing effect. ④ Adding amphoteric polyacrylamide dry strength agent to coat APMP after APMP refining avoids the impact of refining on the coating effect of the amphoteric polyacrylamide dry strength agent.

[0040] The following section will describe several detailed comparative embodiments and the solution of this embodiment.

[0041] Implementation Case 1: (Control Group)

[0042] Please see Figure 2 , Figure 2This is a schematic diagram of the control group example, which includes 201-APMP semi-dry pulp, 202-pulp dispersing, 203-APMP pulp tower, 204-disc mill, 205-pulp forming tower, 206-pulp mixing and sheet forming, and 207-clarification water tower. APMP semi-dry pulp with a dryness of 30% was diluted with clarified water and dispersed into a 4% concentration APMP pulp in a pulp dispersing mill. After grinding in a disc mill, a mechanical pulp with a freeness of 220 mL was obtained. Its strength was evaluated by mixing it with NBKP / LBKP pulp and forming sheets. Specific test results are shown in Appendix Table 1.

[0043] Implementation Case 2: (Conventional Coating Treatment Solution)

[0044] Please see Figure 3 , Figure 3 This is a schematic diagram of a conventional coating treatment scheme embodiment, which can also include 201-APMP semi-dry pulp, 202-dispersed pulp, 203-APMP pulp tower, 204-disc mill, 205-pulp forming tower, 206-pulp mixing and papermaking, and 207-clarification water tower; take APMP semi-dry pulp with 30% dryness, dilute it with clarified water, disperse the APMP semi-dry pulp into APMP pulp with 4% concentration in the dispersed pulper, add 3000ppm PAC to treat (208) the anionic waste in the APMP pulp, and then add 40kg of glyoxal modified polyacrylamide GPAM (ordinary GPAM 209) for coating. After grinding in the disc mill, a mechanical pulp with a freeness of 220mL is obtained. The strength is evaluated by mixing NBKP / LBKP pulp and papermaking. The specific test results are shown in Appendix Table 1.

[0045] Implementation Case 3: (PAC Addition and Optimization Improves Anion Waste Treatment)

[0046] Please see Figure 4 , Figure 4 This is a schematic diagram of the PAC addition and optimization implementation example, which can also include 201-APMP semi-dry pulp, 202-slurry dispersing, 203-APMP pulp tower, 204-disc mill, 205-slurry forming tower, 206-slurry mixing and papermaking, and 207-clarification water tower; take APMP semi-dry pulp with 30% dryness, add 3000ppm PAC (208) to the clarified water required for dispersing, dissipate the APMP semi-dry pulp into APMP slurry with a concentration of 4% in the dispersing mill, and then add 40kg of glyoxal modified polyacrylamide GPAM (ordinary GPAM 209) for coating. After grinding in the disc mill, a mechanical pulp with a freeness of 220mL is obtained. The strength is evaluated by mixing and papermaking with NBKP / LBKP slurry. The specific test results are shown in Appendix Table 1.

[0047] Implementation Example 4: (An embodiment of the coating scheme of this application, a multi-layer reinforced coating scheme)

[0048] Please see Figure 5 , Figure 5 This is a schematic diagram of the coating scheme according to an embodiment of this application, which may include 201-APMP semi-dry pulp, 202-pulp dispersing, 203-APMP pulp tower, 204-disc mill, 205-pulp forming tower, 206-pulp preparation and sheet forming, and 207-clarification water tower; 30% dryness of APMP semi-dry pulp is taken, and 5 kg of cationic polyacrylamide dry strength agent (210) is added to the semi-dry pulp conveyor belt to the pulp dispersing machine by atomization spraying; 3000 ppm PAC (208) is added to the clarified water required for pulp dispersing, and the APMP semi-dry pulp is dispersed into APMP slurry with a concentration of 4% in the pulp dispersing machine. After being milled by the disc mill, a mechanical pulp with a freeness of 220 mL is obtained, and then 40 kg of amphoteric dry strength agent (211) is added. The APMP is uniformly coated by a static mixer and enters the pulp forming tower. The strength is evaluated by mixing and forming sheets with NBKP / LBKP, and the specific test results are shown in Appendix Table 1.

[0049] Appendix 1 (Paper Strength Data for APMP Pulp with Different Coating Processes) is as follows:

[0050]

[0051] Previous APMP slurry pretreatment and coating were mainly carried out in APMP thin slurry (4-6% concentration). However, this scheme begins coating in the semi-dry state of APMP slurry, making full use of the entire process of APMP semi-dry slurry → slurry dispersing → grinding → slurry preparation and papermaking. The multi-layer coating scheme not only utilizes the adhesion effect of dry strength agent polymers, but also selects two types of dry strength agents with different charges. Through the adsorption effect of "+" and "-" charges, the adhesion of the dry strength agent to the surface of APMP fibers is enhanced. In addition, the optimized selection of PCA addition points has significantly improved the effect of PAC on the anionic waste treatment of APMP slurry. Under the same amount of coating agent, it further promotes the improvement of APMP strength after coating.

[0052] The pulp prepared by the method in this application undergoes a series of pretreatments during the process of separating APMP (alkaline hydrogen peroxide mechanical pulp) semi-dry pulp into finished pulp, including fiber charge modification and coating reinforcement, to improve the overall strength of APMP, thereby increasing the proportion of APMP pulp in the paper or increasing the ash content of the paper, thus reducing the consumption of chemical pulp fibers and saving costs.

[0053] In addition, this application also provides a paper product, which can be obtained by preparing the pulp as described in the above embodiments. Other preparation process features and parameters of the paper product are within the understanding of those skilled in the art and will not be described here.

[0054] The above description is only a part of the embodiments of this application and does not limit the scope of protection of this application. Any equivalent device or equivalent process transformation made based on the content of this application specification and drawings, or direct or indirect application in other related technical fields, are similarly included in the patent protection scope of this application.

Claims

1. A method for preparing pulp, characterized in that, The preparation method includes: A cationic dry strength agent is sprayed onto the surface of a semi-dry pulp of an alkaline hydrogen peroxide mechanical pulp with a dryness of 30%. The cationic dry strength agent is a cationic polyacrylamide polymer with a molecular weight of 6 million to 12 million. Add polyaluminum chloride to the slurry water; The semi-dry slurry of alkaline hydrogen peroxide mechanical slurry with a surface sprayed with a cationic dry strength agent is mixed with slurry water containing polyaluminum chloride to form a slurry. The pulp after it has been loosened is then refined; An amphoteric dry strength agent, namely amphoteric polyacrylamide, is added to the refined pulp. The amphoteric dry strength agent has a molecular weight of 6 million to 12 million. The amount of the cationic dry strength agent added is 3-20 kg / ton of slurry.

2. The preparation method according to claim 1, characterized in that, The concentration of the cationic dry strength agent is 0.1-1.0%.

3. The preparation method according to claim 1, characterized in that, In the step of adding polyaluminum chloride to the pulp water, the amount of polyaluminum chloride used is 1000-20000 ppm relative to the oven-dry amount of the alkaline hydrogen peroxide mechanical pulp.

4. The preparation method according to claim 3, characterized in that, The amount of polyaluminum chloride used is 2000-3000 ppm relative to the oven-dry amount of the alkaline hydrogen peroxide mechanical slurry.

5. The preparation method according to claim 1, characterized in that, The dosage of the amphoteric polyacrylamide is 10-60 kg / ton of slurry.

6. A type of pulp, characterized in that, The pulp is prepared by the preparation method according to any one of claims 1-5.

7. A paper product, characterized in that, The paper product is obtained by preparing the pulp according to claim 6.

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