Paper product, paper pulp, papermaking mechanical pulp and treatment method thereof

Abstract

The invention provides a paper product, paper pulp, papermaking mechanical pulp and a treatment method thereof. The treatment method comprises the following steps: grinding mechanical pulp; adding a dispersing agent into the ground mechanical pulp, and stirring; wherein the dispersing agent comprises any one of anionic polyacrylamide and sodium carboxymethyl cellulose; and adding a reinforcing agent into the mechanical pulp. According to the treatment method of the papermaking mechanical pulp provided by the embodiment of the invention, the dispersing agent is added into the mechanical pulp, the dispersing agent can fully disperse the mechanical pulp, and the dispersing agent can be uniformly dispersed and filled among the mechanical pulp, so that hydroxyl groups of the mechanical pulp can be fully exposed, and the binding opportunity of the mechanical pulp and other fibers or chemical drugs is improved, so that the strength is improved. According to the treatment method, the finished product mechanical pulp is mainly pretreated, and the strength of the mechanical pulp is improved, so that the use amount of the mechanical pulp in the papermaking process is increased, the papermaking cost of paper is reduced, and the method is more in line with the development trend of green and environment-friendly papermaking.

Description

Technical Field

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

[0002] With the continuous development of Internet media, the demand for paper-based books, magazines and other industries is decreasing. This has led to overcapacity in the papermaking industry and increasingly fierce competition in the industry. At the same time, the rise in raw material prices has led to a decline in product profits, and papermaking companies are under pressure to face transformation and suspension of production. Papermaking is a high-resource consumption industry. Under the current background of carbon neutrality and carbon peak, the papermaking industry needs to save energy and reduce emissions.

[0003] The raw materials used in conventional papermaking are mainly chemical pulp and mechanical pulp. Chemical pulp is characterized by high strength and low yield, while mechanical pulp (including BCTMP, APMP, etc.) is characterized by low strength, high thickness and high yield. In order to reduce the consumption of papermaking raw materials, increasing the amount of mechanical pulp can effectively reduce the consumption of plant resources, but the high amount of mechanical pulp is not good for the strength of paper, and the strength of paper needs to be improved. At present, the means to improve the strength of paper generally include using dry strength enhancers, increasing long fiber pulp, filler modification and other methods to improve strength. Summary of the invention

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

[0005] Grinding the mechanical pulp;

[0006] Adding a dispersant to the ground mechanical pulp and stirring the pulp; wherein the dispersant comprises any one of anionic polyacrylamide and sodium carboxymethyl cellulose;

[0007] Adding reinforcing agents to mechanical pulp.

[0008] In some embodiments, the dispersant is anionic polyacrylamide with a relative molecular weight of 2.5 million to 3.5 million.

[0009] In some embodiments, the dispersant is added in an amount of 0.5-2.0 kg / ton of slurry.

[0010] In some embodiments, in the step of grinding the mechanical pulp, the grinding concentration is 3.0-6.0%, and the grinding freeness is 150-350 ml.

[0011] In some embodiments, the enhancer includes cationic polyacrylamide and cationic starch; wherein the cationic polyacrylamide has a molecular weight of 8 million to 12 million and an ionicity of 20% to 40%.

[0012] In some embodiments, the amount of cationic polyacrylamide added is 0.5-1.5 kg / ton of pulp; the amount of cationic starch added is 5.0-20.0 kg / ton of pulp.

[0013] In some embodiments, the cationic starch is quaternary ammonium salt-etherified modified cassava starch with a degree of substitution of 0.03-0.07 and a molecular weight of 400,000 to 800,000.

[0014] In a second aspect, an embodiment of the present application provides a papermaking mechanical pulp, which is prepared by the processing method described in the above embodiment.

[0015] In a third aspect, an embodiment of the present application provides a pulp, wherein the pulp includes chemical pulp and the mechanical pulp described in the above embodiments.

[0016] 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.

[0017] The method for processing mechanical pulp for papermaking provided in the embodiment of the present application is mainly to pre-treat the finished mechanical pulp to improve the strength of the mechanical pulp, thereby increasing the amount of mechanical pulp used in the papermaking process, reducing the cost of papermaking, and being more in line with the development trend of green and environmentally friendly papermaking. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] 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.

[0019] Figure 1 It is a schematic flow chart of an embodiment of a method for processing papermaking mechanical pulp of the present application. DETAILED DESCRIPTION

[0020] 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.

[0021] 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.

[0022] 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.

[0023] The present application embodiment first provides a method for processing papermaking mechanical pulp, see Figure 1 , Figure 1 It is a flow chart of an embodiment of a method for processing papermaking mechanical pulp of the present application. The method for processing papermaking mechanical pulp includes but is not limited to the following steps.

[0024] Step S100, grinding the mechanical pulp.

[0025] In step S100, the refining concentration is 3.0-6.0%, and the specific refining concentration can be 3%, 3.2%, 3.5%, 3.8%, 4.3%, 4.5%, 5%, 5.6%, 5.7%, 6% and other values; the refining freeness is 150-350ml, and specifically can be 150ml, 155ml, 180ml, 250ml, 350ml and other values, which are not specifically limited here. The mechanical pulp after refining is kept uniformly stirred in the storage tank.

[0026] Please continue reading Figure 1The papermaking mechanical pulp processing method in the embodiment of the present application also includes step S200, adding a dispersant to the ground mechanical pulp and stirring it.

[0027] Among them, the dispersant is a fiber dispersant. For the papermaking process, the fiber is insoluble in water and has a tendency to aggregate in an aqueous solution. The fiber dispersant can form a double-layer structure on the fiber surface. The polar end of the outer dispersant has a strong affinity with water, which increases the degree to which the fiber is wetted by water. The fibers are kept away from each other due to electrostatic repulsion, forming a good fiber dispersion. When using fiber dispersants, the chemicals that can be used as fiber dispersants are analyzed according to their mechanism of action. Such chemicals are generally divided into three categories: The first category is surfactants, which mainly include two types: 1) non-ionic dispersants, such as fatty alcohol polyoxyethylene ether methyl silane and oleic acid polyoxyethylene ester;

[0028] 2) Anionic dispersants, such as sodium sulfate of fatty alcohol polyoxyethylene ether, Turkey red oil, sodium cellulose sulfate, sodium alkyl diphenyl ether sulfonate, alkylphenol polyoxyethylene ether phosphate. The second category is some electrolyte inorganic salts, including potassium pyrophosphate, sodium hexametaphosphate, etc. The third category is water-soluble polymers, also known as water-soluble resins or water-soluble polymers. It is a hydrophilic polymer material that can dissolve or swell in water to form a solution or dispersion. It is currently used more in slurry dispersion. Its typical representatives are polyethylene oxide and polyacrylamide. When using synthetic polymers as dispersants, the choice of molecular weight is the key. For example, for polyacrylamide, it is an effective thickener for dispersed materials at low molecular weight, and an important flocculant at high molecular weight. Therefore, the selection of a suitable molecular weight has a decisive influence on the quality of the slurry dispersion state. Methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, etc. are typical water-soluble polymers and can also be used as fiber dispersants.

[0029] After many tests and screenings, the treatment method in the embodiment of the present application selects any one of anionic polyacrylamide (PAM) and sodium carboxymethyl cellulose as a dispersant. Further, anionic polyacrylamide (PAM) can be selected, and its sodium salt can be used as a fiber dispersant. The relative molecular weight is selected from 2.5 million to 3.5 million, such as a product of about 3 million. The PAM molecular chain contains carboxyl groups, which has the effect of reducing surface tension and helps water to wet the fiber. When PAM is added to the slurry, a bimolecular structure can be formed on the surface of the fiber and filler. The outer layer of the dispersant has a strong affinity with water, which increases the degree to which solid particles such as fibers and fillers are wetted by water. Solid particles such as fibers and fillers are kept away from each other due to electrostatic repulsion, achieving a good dispersion effect. Therefore, adding a polyacrylamide fiber dispersant to the mechanical pulp is beneficial to improving the bonding strength of the mechanical pulp with the cationic reinforcing polymer added thereafter. Laboratory experiments have verified that the mechanical pulp fibers treated by the above method have significantly improved the strength of the hand-made sheets. After test comparison, the addition amount of pretreatment agent 1 (dispersant) is 0.5-2.0kg / ton pulp, specifically 0.5kg / ton pulp, 0.55kg / ton pulp, 0.6kg / ton pulp, 0.68kg / ton pulp, 0.8kg / ton pulp, 1.0kg / ton pulp, 1.5kg / ton pulp, 2.0kg / ton pulp, etc. If the addition amount is too small, the dispersion effect is not good, and if the addition amount is too large, the refining energy consumption increases, and the fiber water filtration performance is affected to a certain extent. After test screening and combined with the actual conditions of the paper mill, the recommended mechanical pulp refining concentration is 3.5-4.5%, and the specific refining concentration can be 3.5%, 3.62%, 3.75%, 3.8%, 4.0%, 4.3%, 4.5% and other values; the refining freeness is 200-300ml, and can be 200ml, 210ml, 215ml, 245ml, 250ml, 280ml, 300ml and other values, which are not specifically limited here. The addition amount of pretreatment agent 1 is 1.0-1.5kg / ton pulp, and can be 1.0kg / ton pulp, 1.05kg / ton pulp, 1.2kg / ton pulp, 1.25kg / ton pulp, 1.38kg / ton pulp, 1.4kg / ton pulp, 1.45kg / ton pulp, 1.5kg / ton pulp and other values.

[0030] Please continue reading Figure 1 The papermaking mechanical pulp processing method in the embodiment of the present application also includes step S300, adding a reinforcing agent to the mechanical pulp.

[0031] In this step, while maintaining uniform stirring for 10 minutes, pretreatment agent 2 (i.e., enhancer) is added to the mechanical pulp. Pretreatment agent 2 is a high molecular weight organic polymer with a molecular weight range of 4 million to 12 million, and may include cationic polyacrylamide, cationic starch, modified chitosan, carboxymethyl cellulose, etc. The high molecular weight and the combination of cation and cation charges and the flocculation effect of the high molecular weight polymer form a spatial network structure, which is beneficial to the combination of mechanical pulp and fiber, and tightly wraps the mechanical pulp fiber, thereby giving the mechanical pulp more bondable hydroxyl groups. At the same time, since the surface of the filler is wrapped with the cationic polymer, the bonding strength between the filler and the fiber can be improved, thereby ultimately improving the strength of the papermaking paper.

[0032] In the treatment method of this embodiment, after many tests and screenings, cationic polyacrylamide and cationic starch are selected as the pretreatment agent 2. The selected cationic polyacrylamide (CPAM) can have a molecular weight of 8 million to 12 million, an ionicity of 20% to 40%, and a preferred dosage of 0.5 to 1.5 kg / ton of pulp, specifically 0.5 kg / ton of pulp, 0.55 kg / ton of pulp, 0.6 kg / ton of pulp, 0.68 kg / ton of pulp, 0.8 kg / ton of pulp, 1.0 kg / ton of pulp and other values.

[0033] Among them, cationic starch is a chemically modified starch, which is a starch ether derivative containing amino groups and carrying a positive charge on the nitrogen atom, which is generated by etherification reaction of various organic amine compounds containing halogen groups or epoxy groups with hydroxyl groups in starch molecules. In the embodiment of the present application, homemade quaternary ammonium salt etherified modified cassava starch was screened, and the degree of substitution was 0.03-0.07, and the molecular weight was controlled at 400,000 to 800,000 after modification. After experimental comparison, the addition amount is 5 to 20 kg / ton of pulp, and specifically can be 5 kg / ton of pulp, 6 kg / ton of pulp, 8 kg / ton of pulp, 8.7 kg / ton of pulp, 10 kg / ton of pulp, 13 kg / ton of pulp, 15 kg / ton of pulp, 18 kg / ton of pulp, 18.6 kg / ton of pulp, 20 / ton of pulp and other values. After experimental screening, the recommended addition amount of pretreatment agent 2 is 8 to 12 kg / ton of pulp.

[0034] In the method for treating mechanical pulp for papermaking in the embodiment of the present application, a dispersant is added to the mechanical pulp, and the dispersant can fully disperse the mechanical pulp, and the dispersant can be evenly dispersed and filled between the mechanical pulps, and the hydroxyl groups of the mechanical pulp can be fully exposed, and its chance of combining with other fibers or chemicals is increased, thereby increasing the strength. The cationic enhancer used can form positive and negative ionic bonds with the anionic dispersant, and in addition, when the anionic dispersant and the cationic enhancer are selected, the two can also form covalent bonds under certain conditions, which can not only tightly wrap the mechanical pulp fibers, but also provide more hydroxyl groups, which is more conducive to hydrogen bonding with the chemical pulp, thereby improving the strength.

[0035] The application of mechanical pulp in papermaking will be introduced below.

[0036] The treated mechanical pulp is mixed with other pulps, and a simulated papermaking process is carried out to add fillers to the paper sheets. This allows the fillers to be effectively adsorbed on the surface of the mechanical pulp fibers to form APMP / filler inclusions, reducing the adverse effects of the fillers on the hydrogen bonding between the fibers. At the same time, it can effectively save the amount of wet-end cationic starch and significantly improve the strength. It can effectively increase the amount of mechanical pulp and reduce the amount of chemical pulp, thereby reducing the consumption of plant fiber resources in the papermaking process.

[0037] Several specific embodiments are described below.

[0038] Implementation Case 1:

[0039] Take a mechanical pulp with a concentration of 4% and a freeness of 250 mL, add cationic starch (addition amount 10 kg / ton pulp) under uniform stirring, and obtain mechanical pulp after uniform stirring (specific results are shown in Table 1). Then simulate the papermaking process of the paper machine, keep the pulp ratio (NBKP: 20 parts; LBKP: 60 parts; mechanical pulp: 20 parts), filler, wet end chemical addition and other conditions the same, and carry out pulp preparation and sheeting to evaluate the strength change. The specific test results are shown in Table 2.

[0040] Implementation Case 2:

[0041] Take a mechanical pulp with a concentration of 4% and a freeness of 250 mL, add dispersant PAM (addition amount 1.0 kg / ton of pulp) under uniform stirring, keep stirring evenly for 10 minutes, then add cationic polyacrylamide (addition amount 0.5 kg / ton of pulp), keep stirring evenly, add cationic starch (addition amount 8 kg / ton of pulp), stir evenly to obtain mechanical pulp (specific results are shown in Table 1), then simulate the papermaking process of the paper machine, keep the pulp ratio (NBKP: 20 parts; LBKP: 60 parts; mechanical pulp: 20 parts), filler, wet end chemical addition and other conditions are the same, carry out pulp preparation and sheeting to evaluate the strength change, the specific test results are shown in Table 2.

[0042] Implementation Case 3:

[0043] Take a mechanical pulp with a concentration of 4% and a freeness of 250 mL, add dispersant PAM (addition amount 1.25 kg / ton of pulp) under uniform stirring, keep stirring evenly for 10 minutes, then add cationic polyacrylamide (addition amount 1.0 kg / ton of pulp), keep stirring evenly, add cationic starch (addition amount 10 kg / ton of pulp), stir evenly to obtain mechanical pulp (specific results are shown in Table 1), then simulate the papermaking process of the paper machine, keep the pulp ratio (NBKP: 20 parts; LBKP: 60 parts; mechanical pulp: 20 parts), filler, wet end chemical addition and other conditions are the same, carry out pulp preparation and sheeting to evaluate the strength change, the specific test results are shown in Table 2.

[0044] Implementation Case 4:

[0045] Take a mechanical pulp with a concentration of 4% and a freeness of 250 mL, add dispersant PAM (addition amount 1.5 kg / ton pulp) under uniform stirring, keep stirring evenly for 10 minutes, then add cationic polyacrylamide (addition amount 1.5 kg / ton pulp), keep stirring evenly, add cationic starch (addition amount 12 kg / ton pulp), stir evenly to obtain mechanical pulp (specific results are shown in Table 1), then simulate the papermaking process of the paper machine, keep the pulp ratio (NBKP: 20 parts; LBKP: 60 parts; mechanical pulp: 20 parts), filler, wet end chemical addition and other conditions are the same, carry out pulp preparation and sheeting to evaluate the strength change, the specific test results are shown in Table 2.

[0046] Table 1 - Mechanical pulp pretreatment strength data.

[0047]

[0048]

[0049] Table 2-Simulated paper machine pulping sheet strength evaluation parameters

[0050]

[0051] By pre-treating the mechanical pulp, dispersing it first, and then adding a polymer cationic enhancer, the positive and negative charges between the polymers are used to form a spatial network structure, tightly wrap the mechanical pulp, provide hydrogen bonding points, and form more bonds with chemical pulp and chemicals, thereby improving the strength of the mechanical pulp. It is mainly to pre-treat the finished mechanical pulp to improve the strength of the mechanical pulp, thereby increasing the amount of mechanical pulp used in the papermaking process, saving papermaking costs, and more in line with the development trend of green and environmentally friendly papermaking.

[0052] When the proportion of mechanical pulp treated by the above method is increased, the amount of chemical pulp can be reduced, and the strength of paper can still be maintained. The mechanical pulp obtained by this treatment method can increase the amount of mechanical pulp and reduce the amount of chemical pulp, thereby saving the consumption of plant resources for papermaking.

[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 treating papermaking mechanical pulp, characterized in that: The processing method comprises: Grinding the mechanical pulp; Adding a dispersant to the ground mechanical pulp and stirring the pulp; wherein the dispersant comprises any one of anionic polyacrylamide and sodium carboxymethyl cellulose; Adding reinforcing agents to mechanical pulp.

2. The processing method according to claim 1, characterized in that: The dispersant is anionic polyacrylamide with a relative molecular weight of 2.5 million to 3.5 million.

3. The processing method according to claim 2, characterized in that: The added amount of the dispersant is 0.5-2.0 kg / ton of slurry.

4. The processing method according to claim 1, characterized in that: In the step of grinding the mechanical pulp, the grinding concentration is 3.0-6.0%, and the grinding freeness is 150-350 ml.

5. The processing method according to claim 1, characterized in that: The reinforcing agent comprises cationic polyacrylamide and cationic starch; wherein the molecular weight of the cationic polyacrylamide is 8 million to 12 million, and the ionicity is 20% to 40%.

6. The processing method according to claim 5, characterized in that: The added amount of the cationic polyacrylamide is 0.5-1.5 kg / ton of pulp; the added amount of the cationic starch is 5.0-20.0 kg / ton of pulp.

7. The processing method according to claim 6, characterized in that: The cationic starch is quaternary ammonium salt etherified modified cassava starch with a substitution degree of 0.03-0.07 and a molecular weight of 400,000 to 800,000.

8. A papermaking mechanical pulp, characterized in that: The papermaking mechanical pulp is prepared by the treatment method described in any one of claims 1-7.

9. A pulp, characterized in that: The pulp includes chemical pulp and the mechanical pulp as claimed in claim 8.

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

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