Paper product, paper pulp and preparation method thereof

Abstract

The invention provides a paper product, 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 semi-dry pulp of alkaline hydrogen peroxide mechanical pulp; adding polyaluminum chloride into the slurry dispersing water; mixing the alkaline hydrogen peroxide mechanical pulp semi-dry pulp of which the surface is sprayed with the cationic dry strength agent with pulp dispersing water added with polyaluminum chloride for pulp dispersing; grinding the dispersed paper pulp; and adding an amphoteric dry strength agent into the ground paper pulp. According to the preparation method of the paper pulp provided by the embodiment of the invention, a series of pretreatment including fiber charge modification, coating enhancement and other treatment means are performed in the process from dispersing of the semi-dry pulp of the APMP (alkaline peroxide mechanical pulp) to pulping, so that the comprehensive strength of the APMP is improved, the proportion of the APMP pulp in the paper is increased or the ash content of the paper is increased, and the paper quality is improved. The consumption of chemical pulp fibers is reduced, and the cost is reduced.

Description

Technical Field

[0001] The present application relates to the technical field of papermaking, and in particular to a paper product, pulp and a preparation method thereof. Background Art

[0002] As global climate change and environmental problems become increasingly severe, governments around the world are strengthening environmental regulations and carbon emission control. Against this backdrop, achieving carbon peak and carbon neutrality has become a global consensus and goal. Carbon peak means that a country or region's carbon dioxide emissions will no longer increase after reaching a peak within a certain period of time, while carbon neutrality is to offset the carbon dioxide emissions through various measures to achieve zero net emissions. In this environment, the papermaking industry has gradually become a general trend in the industry to use high-yield pulp as a raw material for the production of paper and other cellulose-based products. High-yield pulp is a process for extracting cellulose fibers from wood by purely mechanical or chemical-mechanical methods. Compared with traditional chemical pulp or mechanical pulp, it has a higher fiber extraction rate, lower energy consumption and less use of chemical additives, thereby reducing carbon emissions and environmental pollution in the production process. Several advantages of using high-yield pulp in environmental protection and carbon peak: 1. High fiber extraction rate: The fiber extraction rate of high-yield pulp is higher than that of traditional processes, which means 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 production: Compared with traditional chemical pulp, the production process of high-yield pulp consumes less energy, which helps to reduce energy consumption and carbon emissions in the entire production process. 3. Reduce chemical additives: Fewer chemical additives are used in the production process of high-yield pulp, which reduces chemical pollution to the environment and reduces the cost and difficulty of treating wastewater. 4. Circular economy: By-products produced in the production process of high-yield pulp, such as lignin, can be recycled and used to produce biofuels, chemical raw materials, etc., which promotes the development of circular economy. 5. Policy support: In order to promote environmental protection and achieve carbon peak targets, the country has introduced a series of policies and incentives to support the research and development and application of environmentally friendly production processes such as high-yield pulp. 6. Market demand: As consumers' awareness of environmental protection and sustainable development increases, the market demand for environmentally friendly paper and cellulose products is also growing, and the use of high-yield pulp can meet this market demand. Cost reduction: The cost per ton of high-yield pulp is much lower than that of chemical pulp. Therefore, in the fierce market competition environment, papermaking companies can balance production costs through the use of high-yield pulp, cope with fierce market competition, and maintain corporate profitability.

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

[0004] A first aspect of an embodiment of the present application provides a method for preparing pulp, the method comprising:

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

[0006] Add polyaluminium chloride to the slurry water;

[0007] The semi-dry pulp of alkaline hydrogen peroxide mechanical pulp with a cationic dry strength agent sprayed on the surface is mixed with pulping water added with polyaluminium chloride to perform pulping;

[0008] Refining the pulp after pulping;

[0009] Add amphoteric dry strength agents 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 cationic dry strength agent is added in an amount of 3-20 kg / ton of pulp.

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

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

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

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

[0017] In a second aspect, an embodiment of the present application provides a pulp, which is prepared by the preparation method described in the above embodiment.

[0018] In a third aspect, an embodiment of the present application provides a paper product, which is prepared using the pulp described in the above embodiment.

[0019] The method for preparing pulp provided in the embodiment of the present application improves the comprehensive strength of APMP (alkaline peroxide mechanical pulp) through a series of pretreatments during the process of APMP (alkaline hydroperoxide mechanical pulp) semi-dry pulping to pulping, including fiber charge modification, coating reinforcement and other treatment methods, thereby increasing the proportion of APMP pulp in the paper or increasing the ash content of the paper, thereby reducing the consumption of chemical pulp fibers and reducing costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. 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 creative work.

[0021] Figure 1 It is a schematic flow chart of an embodiment of a method for preparing pulp of the present application;

[0022] Figure 2 is a schematic flow diagram of an embodiment of a control group;

[0023] Figure 3 It is a schematic diagram of a flow chart of an embodiment of a conventional coating treatment scheme;

[0024] Figure 4 It is a flow chart of an embodiment of adding optimization adjustment of PAC;

[0025] Figure 5 It is a schematic diagram of the coating solution process of one embodiment of the present application. DETAILED DESCRIPTION

[0026] The present application is further described in detail below in conjunction with the accompanying drawings and examples. It is particularly noted that the following examples are only used to illustrate the present application, but are not intended to limit the scope of the present application. Similarly, the following examples are only some embodiments of the present application rather than all embodiments, and all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present application.

[0027] The terms "first", "second", and "third" in the embodiments of the present application are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. Thus, the features defined as "first", "second", and "third" can expressly or implicitly include at least one of the features. In the description of the present application, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined. In the embodiments of the present application, all directional indications (such as up, down, left, right, front, back...) are only used to explain the relative position 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 of their variations 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.

[0028] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0029] The technical solution provided in this application is mainly to improve the bonding strength of mechanical pulp while minimizing the adverse effect of increased APMP dosage on paper strength through semi-dry pulp pretreatment and multi-layer coating treatment process of APMP (alkaline hydrogen peroxide mechanical pulp), thereby reducing the cost per ton of paper on the basis of meeting the paper quality requirements. It not only reduces the cost of paper raw materials, but also increases the proportion of high-yield pulp in the paper pulp structure, which is more in line with the development trend of green and environmentally friendly papermaking.

[0030] See also Figure 1 , Figure 1 1 is a flow chart of an embodiment of a method for preparing pulp of the present application, and the method for preparing pulp includes but is not limited to the following steps.

[0031] Step S100, spraying a cationic dry strength agent onto the surface of the semi-dry pulp of the alkaline hydrogen peroxide mechanical pulp.

[0032] Before APMP (alkaline peroxide mechanical pulp) semi-dry pulp is transported to the pulping machine for pulping, a cationic dry strength agent is added to the fiber surface by spraying. The cationic dry strength agent is CPAM positive polyacrylamide 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, the specific value is 6-8 million; the added 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% and other values. In this embodiment, it can be 0.2-0.4%; the amount of cationic dry strength agent is 3-20kg / ton of pulp, for example, it can be 3kg / ton of pulp, 3.8kg / ton of pulp, 4.7kg / ton of pulp, 5kg / ton of pulp, 7kg / ton of pulp, 9kg / ton of pulp, 13kg / ton of pulp, 16kg / ton of pulp, 18kg / ton of pulp, 20kg / ton of pulp and other values. In this embodiment, 5-6kg / ton of pulp can be selected.

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

[0034] In step S200, PAC (polyaluminium chloride) is added to the APMP slurry water in advance to treat the anionic garbage in the APMP slurry through charge adsorption and flocculation, thereby reducing the adverse effects of the anionic garbage on the adsorption and coating effects of the dry strength agent and APMP fibers. The amount of PAC relative to the APMP slurry is 1000-20000ppm (absolute dry to absolute dry), for example, it can be 1000ppm, 2000ppm, 2300ppm, 3400ppm, 5000ppm, 8700ppm, 10000ppm, 1200ppm, 14000ppm, 15000ppm, 15600ppm, 18000ppm, 20000ppm, etc., and in this embodiment, it can be 2000-3000ppm.

[0035] Please continue reading Figure 1 The preparation method in this embodiment further includes step S300, mixing the semi-dry pulp of alkaline hydrogen peroxide mechanical pulp with a cationic dry strength agent sprayed on the surface with pulping water added with polyaluminium chloride for pulping.

[0036] Step S400, refining the pulp after pulping.

[0037] Step S500, adding an amphoteric dry strength agent to the refined pulp.

[0038] After APMP is refined, an amphoteric dry strength agent is added to coat the APMP fiber through the charge adsorption and adhesion of the amphoteric dry strength agent and the APMP fiber, thereby increasing the bonding strength between APMP and other chemical fibers in the subsequent papermaking process. The amphoteric dry strength agent can be amphoteric polyacrylamide, with a molecular weight of about 6 million to 12 million, such as 6 million, 6.5 million, 7 million, 8 million, 10 million and 12 million. In this embodiment, 8 million to 9 million can be specifically selected. Among them, the amount of the amphoteric dry strength agent is 10-60 kg / ton of pulp (absolute dry to stock solution), for example, it can be 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, 60 kg / ton of pulp, etc., and in this embodiment, it can be 40-60 kg.

[0039] The method for preparing pulp in the embodiment of the present application has the following characteristics: ① A cationic dry strength agent (CPAM) is added in the semi-dry pulp state of APMP, and the dry strength agent is uniformly adsorbed on the surface by adsorption through atomization spraying. When the amount added is small, it can have the effect of uniformly coating the surface of APMP fibers. ② PAC is added to the APMP pulping water, so that PAC first treats the anionic garbage in the clarified water, and then further treats the anionic garbage in the APMP pulp during the APMP pulping process, thereby ensuring the treatment effect to the maximum extent. In this scheme, PAC is added, and the PCD of the 4% APMP pulp after pulping is -200 to -300μeq / L (while PAC is added after APMP pulping, the PCD of the 4% APMP pulp is about -500 to -600μeq / L). ③ The multi-layer coating scheme of first cationic coating and then amphoteric coating can better wrap the dry strength agents with different charges on the fiber surface, improve the adhesion, and at the same time increase the retention rate of the dry strength agent in the paper during the high vacuum suction and pressing process of the paper machine, thereby improving the strengthening effect. ④ After APMP is refined, the amphoteric polyacrylamide dry strength agent is added to coat APMP, which can avoid the influence of refining on the coating effect of the amphoteric polyacrylamide dry strength agent.

[0040] Several detailed comparative embodiments and the scheme description of this embodiment will be introduced below.

[0041] Implementation Case 1: (Control Group)

[0042] See also Figure 2 , Figure 2201-APMP semi-dry pulp, 202-loose pulp, 203-APMP pulp tower, 204-disc mill, 205-slurry tower, 206-slurry preparation and 207-clarification water tower. Take 30% dryness of APMP semi-dry pulp, dilute with clarified water, and disperse the APMP semi-dry pulp into 4% APMP slurry in the pulping machine. After grinding in the disc mill, the mechanical pulp with a freeness of 220mL is obtained, and the strength of the sheet is evaluated by mixing with NBKP / LBKP pulp. The specific test results are shown in Appendix 1.

[0043] Implementation case 2: (conventional coating treatment solution)

[0044] See also Figure 3 , Figure 3 It is a flow diagram of an embodiment of a conventional coating treatment scheme, which may also include 201-APMP semi-dry pulp, 202-loose pulp, 203-APMP pulp tower, 204-disc mill, 205-slurry tower, 206-slurry preparation and 207-clarification water tower; take APMP semi-dry pulp with a dryness of 30%, dilute it with clarified water, and disperse the APMP semi-dry pulp into APMP pulp with a concentration of 4% in a pulp disperser, add 3000ppm PAC to treat (208) anionic garbage in the APMP pulp, and then add 40kg of glyoxal-modified polyacrylamide GPAM (ordinary GPAM 209) for coating, and obtain mechanical pulp with a freeness of 220mL after grinding in a disc mill, and evaluate the strength of the pulp sheet made with NBKP / LBKP. The specific test results are shown in Appendix 1.

[0045] Implementation case 3: (PAC addition optimization adjustment, anion waste treatment effect improvement)

[0046] See also Figure 4 , Figure 4 It is a flow chart of an embodiment of PAC addition optimization adjustment, which may also include 201-APMP semi-dry pulp, 202-loose pulp, 203-APMP pulp tower, 204-disc mill, 205-slurry tower, 206-slurry preparation and 207-clarification water tower; take APMP semi-dry pulp with 30% dryness, add 3000ppm PAC (208) to the clarified water required for the loose pulp, and disperse the APMP semi-dry pulp into 4% APMP slurry in the pulping machine, and then add 40kg of glyoxal-modified polyacrylamide GPAM (ordinary GPAM 209) for coating, and obtain mechanical pulp with a freeness of 220mL after grinding in the disc mill, and evaluate the strength of the pulp sheet made with NBKP / LBKP. The specific test results are shown in Appendix 1.

[0047] Implementation Case 4: (Coating solution of an embodiment of the present application, multi-layer enhanced coating solution)

[0048] See also Figure 5 , Figure 5 This is a schematic diagram of the coating scheme flow of an embodiment of the present application, which can also include 201-APMP semi-dry pulp, 202-loose pulp, 203-APMP pulp tower, 204-disc mill, 205-slurry tower, 206-slurry preparation and papermaking, and 207-clarification water tower; take APMP semi-dry pulp with a dryness of 30%, add 5kg of cationic polyacrylamide dry strength agent (210) by atomization spraying on the conveyor belt of the semi-dry pulp to the pulping machine; add 3000ppm PAC (208) to the clarified water required for the pulping, and in the pulping machine, the APMP semi-dry pulp is decomposed into 4% APMP slurry, and after the pulping is refined by the disc mill, a mechanical pulp with a freeness of 220mL is obtained, and then 40kg of amphoteric dry strength agent (211) is added, and the APMP is uniformly coated by a static mixer and enters the pulping tower. The strength of the sheet is evaluated with NBKP / LBKP mixed pulp, and the specific test results are shown in Appendix 1.

[0049] Appendix 1 (Strength data of paper made with APMP slurry with different coating processes) is as follows:

[0050]

[0051] In the past, APMP slurry pretreatment and coating were mainly carried out in APMP dilute slurry (4-6% concentration), while this scheme starts coating in the semi-dry APMP slurry state, making full use of the entire process of APMP semi-dry slurry → loose slurry → grinding → slurry preparation and papermaking, and adopts a multi-layer coating scheme. It not only utilizes the adhesion effect of dry strength agent polymers, but also selects two types of charge dry strength agents. Through the adsorption effect of "+" and "-" charges, the adhesion strength of the dry strength agent on the APMP fiber surface is enhanced; in addition, the optimized selection of PCA addition points has significantly improved the anionic waste treatment effect of PAC on APMP slurry, and further promoted the improvement of APMP strength after coating under the same coating drug dosage.

[0052] The pulp obtained by the preparation method of the embodiment of the present application undergoes a series of pretreatments during the process from APMP (alkaline peroxide mechanical pulp) semi-dry pulping to pulping, including fiber charge modification, coating reinforcement and other treatment methods, so as to improve the comprehensive strength of APMP, thereby increasing the proportion of APMP pulp in the paper or increasing the ash content of the paper, thereby reducing the consumption of chemical pulp fibers and reducing costs.

[0053] In addition, the embodiment of the present application further provides a paper product, which can be obtained by using the pulp in the above embodiment. Other preparation process characteristics and parameters of the paper product are within the scope of understanding of those skilled in the art and will not be described in detail here.

[0054] The above descriptions are only some embodiments of the present application, and do not limit the protection scope of the present application. Any equivalent device or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly used in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A method for preparing pulp, characterized in that: The preparation method comprises: Spraying a cationic dry strength agent onto the semi-dry pulp surface of alkaline hydrogen peroxide mechanical pulp; Add polyaluminium chloride to the slurry water; The semi-dry pulp of alkaline hydrogen peroxide mechanical pulp with a cationic dry strength agent sprayed on the surface is mixed with pulping water added with polyaluminium chloride to perform pulping; Refining the pulp after pulping; Add amphoteric dry strength agents to the refined pulp.

2. The preparation method according to claim 1, characterized in that: The cationic dry strength agent is a positive polyacrylamide polymer; the molecular weight of the positive polyacrylamide polymer is 6 million to 12 million.

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

4. The preparation method according to claim 1, characterized in that: The added amount of the cationic dry strength agent is 3-20 kg / ton of pulp.

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

6. The preparation method according to claim 5, characterized in that: The dosage of the polyaluminium chloride is 2000-3000 ppm relative to the absolute dry dosage of the alkaline hydrogen peroxide mechanical pulp.

7. The preparation method according to claim 1, characterized in that: In the step of adding an amphoteric dry strength agent to the pulp after refining, the amphoteric dry strength agent is an amphoteric polyacrylamide, and the molecular weight of the amphoteric polyacrylamide is between 6 million and 12 million.

8. The preparation method according to claim 7, characterized in that: The dosage of the amphoteric polyacrylamide is 10-60kg / ton of pulp.

9. A pulp, characterized in that: The pulp is prepared by the preparation method according to any one of claims 1 to 8.

10. A paper product, characterized in that: The paper product is prepared by using the pulp described in claim 9.

Images