High-strength paper tube base paper and preparation method thereof

Abstract

The invention discloses high-strength paper tube raw paper and a preparation method thereof, and relates to the technical field of paper tube raw paper. The method specifically comprises the following steps: S1, pulping a waste paper raw material, screening, and removing impurities to obtain paper pulp grinding liquid; s2, performing spin-drying on the pulp ground pulp to prepare pulp, adding starch particles, a dry strength agent, a waterproof agent and a modifier, and performing uniform ultrasonic dispersion to obtain pulp; s3, the paper pulp is subjected to papermaking treatment, squeezing dehydration, drying and calendaring, and paper tube body paper is obtained; according to tests, the paper tube base paper prepared by the invention has the characteristics of high internal bonding strength and large burst index.

Description

Technical Field

[0001] The present invention relates to the technical field of base paper for paper tubes, and specifically to a high-strength base paper for paper tubes and a preparation method thereof. Background Art

[0002] Base paper for paper tubes is a special paper specifically used for manufacturing paper tubes, usually made of wood pulp, waste paper pulp or other fiber raw materials. After being processed through processes such as multi-layer lamination, winding, and gluing, it forms a paper tube with certain strength and hardness. Base paper for paper tubes is the core material of paper tubes, and its performance directly affects the final quality of paper tubes.

[0003] The main raw material of base paper for paper tubes is waste paper pulp, which has a wide range of sources, including office documents, newspapers, magazines, cartons, and various packaging materials. Using waste paper pulp to prepare base paper for paper tubes can not only reduce the consumption of forest resources but also reduce the generation of solid waste, with significant economic and environmental benefits; waste paper pulp, as an important renewable resource, has an irreplaceable position in the paper-making industry. However, the fiber length and chemical components in waste paper pulp are unstable, resulting in difficulty in ensuring the strength and quality of the paper; in addition, the fibers in waste paper pulp will become keratinized after multiple recycling uses, further reducing the flexibility and bonding ability of the fibers, and there are more impurities, resulting in lower strength of the prepared paper tubes, which limits its application in high-end paper production.

[0004] In summary, to solve the above problems, it is of great significance to prepare a high-strength base paper for paper tubes. Summary of the Invention

[0005] The purpose of the present invention is to provide a high-strength base paper for paper tubes and a preparation method thereof to solve the problems raised in the prior art.

[0006] To achieve the above purpose, the present invention provides the following technical solutions:

[0007] A preparation method of a high-strength base paper for paper tubes, comprising the following steps:

[0008] S1: Pulping, screening, and impurity removal of waste paper raw materials to obtain pulp grinding slurry;

[0009] S2: Adding starch particles, dry strength agent, waterproof agent, and modifier to the slurry prepared after centrifugal dehydration of the pulp grinding slurry, and ultrasonic dispersing evenly to obtain pulp;

[0010] S3: Performing papermaking treatment on the pulp, pressing for dehydration, drying, and calendering to obtain base paper for paper tubes.

[0011] Preferably, in step S2, the concentration of the slurry prepared after centrifugal dehydration is 1.5-2 wt%.

[0012] More preferably, the pulp comprises the following raw materials by mass: 100 parts of pulp, 1 to 1.5 parts of starch granules, 0.1 to 0.2 parts of dry strength agent, 0.3 to 0.5 parts of waterproof agent, and 0.05 to 0.1 parts of modifier.

[0013] More preferably, the modifier comprises the following raw materials by mass: 0.01 to 0.02 parts of modified polyacrylamide, 0.04 to 0.06 parts of modified nano-silica.

[0014] More preferably, the preparation method of the modified polyacrylamide comprises the following steps: (1) Mix 40wt% acrylamide aqueous solution, N,N-bis(oxiran-2-ylmethyl)prop-2-enamide, and sodium methallylsulfonate evenly, add 30wt% sulfuric acid and diethylaminoethyl methacrylate and stir evenly to obtain a reaction monomer solution;

[0015] (2) Add disodium ethylenediaminetetraacetate to deionized water and stir evenly. Under a nitrogen atmosphere, heat to 90 - 95°C, add ammonium persulfate and stir evenly. Gradually dropwise add the reaction monomer solution, stir at 90 - 95°C for 2 - 3 h, filter, and dry to obtain modified polyacrylamide.

[0016] More preferably, the reaction monomer solution comprises the following raw materials by mass: 110 - 120 parts of 40wt% acrylamide aqueous solution, 0.2 - 0.4 parts of N,N-bis(oxiran-2-ylmethyl)prop-2-enamide, 0.3 - 0.4 parts of sodium methallylsulfonate, 20 - 25 parts of deionized water, 8 - 10 parts of 30wt% sulfuric acid, 6.5 - 7 parts of diethylaminoethyl methacrylate;

[0017] The modified polyacrylamide comprises the following raw materials by mass: 0.05 - 0.1 parts of disodium ethylenediaminetetraacetate, 100 - 120 parts of deionized water, 0.1 - 0.3 parts of ammonium persulfate, 110 - 120 parts of reaction monomer solution.

[0018] More preferably, the preparation method of the modified nano-silica comprises the following steps: (1) Add nano-silica to 60% ethanol solution and disperse evenly by ultrasonic wave. Add 3-aminopropyltriethoxysilane and stir at 50 - 60°C for 40 - 60 min, filter, wash, and dry to obtain amino-modified nano-silica;

[0019] (2) Add amino-modified nano-silica to deionized water and disperse evenly by ultrasonic wave. Add N,N-diethyl-2-oxiranecarboxamide and potassium hydroxide and stir at 40 - 45°C for 2 - 3 h to obtain modified nano-silica.

[0020] More preferably, the amino-modified nano-silica comprises the following raw materials in parts by mass: 3-5 parts of nano-silica, 100-120 parts of 60% ethanol solution, and 1-3 parts of 3-aminopropyltriethoxysilane;

[0021] The modified nano-silica comprises the following raw materials in parts by mass: 2-4 parts of amino-modified nano-silica, 70-80 parts of deionized water, 1-2 parts of N,N-diethyl-2-epoxyethanecarboxamide, and 0.3-0.5 part of potassium hydroxide.

[0022] Among them, in step S3, the drying temperature is 100-105 °C

[0023] Compared with the prior art, the beneficial effects of the present application are as follows:

[0024] (1) In the present invention, the prepared modified polyacrylamide is introduced into the pulp. Polyacrylamide is a water-soluble high-molecular compound. By introducing cationic monomers for polymerization, cationic polyacrylamide is prepared. There are a large number of positively charged groups in the molecular chain segments, which can combine with the negatively charged fibers in the pulp, flocculate the small molecular particles in the pulp, and improve the mechanical interception, thereby improving the strength and uniformity of the base paper of the paper tube. However, cationic polyacrylamide has problems such as low molecular weight and poor stability, resulting in poor flocculation effect and low strength of the prepared base paper of the paper tube. In the preparation of the modified polyacrylamide in the present invention, N,N-bis(2-oxiranylmethyl)prop-2-enamide is introduced as a branched cross-linking agent. It has multiple reactive groups and can undergo a cross-linking reaction with polyacrylamide to form a three-dimensional network structure, improving the stability and molecular weight of polyacrylamide, and thus improving the strength of the base paper of the paper tube. However, the amount of N,N-bis(2-oxiranylmethyl)prop-2-enamide introduced should not be too much, which will cause the molecular chain segments of polyacrylamide to be too large and the cross-linking density to be too high, resulting in ineffective dispersion in the pulp and poor flocculation effect, leading to a decrease in the strength of the base paper of the paper tube.

[0025] (2) The present invention also introduces modified nano-silica into the pulp. Nano-silica has a high specific surface area. After being introduced into the pulp, it can improve the strength and flexibility of the base paper of the paper tube and contribute to the coating and dyeing of the functional coating in the subsequent process. In the present invention, nano-silica is surface-modified with 3-aminopropyltriethoxysilane to introduce amino groups and graft with N,N-diethyl-2-epoxyethanecarboxamide. On the one hand, it improves the dispersion of nano-silica in the system, and on the other hand, the grafted groups also contribute to the cross-linking of polyacrylamide, thereby improving the strength of the base paper of the paper tube. Specific embodiments

[0026] Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of the present invention.

[0027] It should be noted that there are no special restrictions on the purchasing manufacturers of all raw materials involved in the present invention. Exemplarily, they include: waste paper raw materials, national waste COCC12, provided by Shanghai Jizhi; starch granules, S18760, provided by Shanghai Jizhi; dry strength agent, JH1216 (solid content 20%), provided by Qingzhou Jinhao; waterproof agent, EUM782 (solid content 41%), provided by Shanghai Aiken; 40wt% acrylamide aqueous solution, provided by Shandong Ruihai New Material Technology Co., Ltd.; CAS number of N,N-bis(oxiran-2-ylmethyl)prop-2-enamide: 87406-72-2; CAS number of sodium methallylsulfonate: 1561-92-8; CAS number of diethylaminoethyl methacrylate: 105-16-8; CAS number of disodium ethylenediaminetetraacetate: 139-33-3; nano-silica, with a particle size of 300-500nm, provided by Zhejiang Manli Nano Technology Co., Ltd.; CAS number of N,N-diethyl-2-oxirane carboxamide: 119163-27-8.

[0028] Among them, in the following examples, "parts" are parts by mass, and the raw materials mentioned above and used below but not mentioned are all commercially available.

[0029] Example 1: Step 1: Preparation of modified polyacrylamide: (1) Mix 90 parts of 40wt% acrylamide aqueous solution, 0.3 parts of N,N-bis(oxiran-2-ylmethyl)prop-2-enamide, and 0.35 parts of sodium methallylsulfonate evenly, add 9 parts of 30wt% sulfuric acid and 6.7 parts of diethylaminoethyl methacrylate and stir evenly to obtain a reaction monomer solution;

[0030] (2) Add 0.07 parts of disodium ethylenediaminetetraacetate to 110 parts of deionized water and stir evenly. Under a nitrogen atmosphere, heat to 90°C, add 0.2 parts of ammonium persulfate and stir evenly. Gradually add 115 parts of the reaction monomer solution and stir at 90°C for 2.5h, filter, and dry to obtain modified polyacrylamide;

[0031] Step 2: Preparation of modified nano-silica:

[0032] (1) Add 4 parts of nano-silica to 110 parts of 60% ethanol solution and disperse evenly by ultrasonic wave. Add 2 parts of 3-aminopropyltriethoxysilane and stir at 55°C for 50min, filter, wash, and dry to obtain amino-modified nano-silica;

[0033] (2) Add 3 parts of amino-modified nano-silica to 75 parts of deionized water and disperse evenly by ultrasonic wave. Add 1.5 parts of N,N-diethyl-2-oxirane carboxamide and 0.4 parts of potassium hydroxide and stir at 40°C for 2.5h to obtain modified nano-silica;

[0034] Step 3: Preparation of base paper for paper tubes:

[0035] S1: Pulping, screening, and impurity removal of waste paper raw materials to obtain pulp grinding slurry;

[0036] S2: After centrifuging the pulp grinding slurry to dryness, prepare 100 parts of a slurry with a concentration of 1.7 wt%, add 1.2 parts of starch granules, 0.1 part of dry strength agent, 0.4 part of waterproof agent, 0.07 part of modifier (0.02 part of modified polyacrylamide, 0.05 part of modified nano-silica), and ultrasonically disperse evenly to obtain pulp;

[0037] S3: Carry out papermaking on the pulp, press for dehydration, dry at 100 °C, and calender to obtain the base paper for paper tubes.

[0038] Example 2: Step 1: Preparation of modified polyacrylamide: (1) Mix 90 parts of 40 wt% acrylamide aqueous solution, 0.3 part of N,N-bis(oxiran-2-ylmethyl)prop-2-enamide, and 0.35 part of sodium methallylsulfonate evenly, add 9 parts of 30 wt% sulfuric acid and 6.7 parts of diethylaminoethyl methacrylate and stir evenly to obtain a reaction monomer solution;

[0039] (2) Add 0.07 part of disodium ethylenediaminetetraacetate to 110 parts of deionized water and stir evenly. Under a nitrogen atmosphere, heat to 90 °C, add 0.2 part of ammonium persulfate and stir evenly. Gradually add 115 parts of the reaction monomer solution, stir at 90 °C for 2.5 h, filter, and dry to obtain modified polyacrylamide;

[0040] Step 2: Preparation of modified nano-silica:

[0041] (1) Add 4 parts of nano-silica to 110 parts of 60% ethanol solution and ultrasonically disperse evenly. Add 2 parts of 3-aminopropyltriethoxysilane, stir at 55 °C for 50 min, filter, wash, and dry to obtain amino-modified nano-silica;

[0042] (2) Add 3 parts of amino-modified nano-silica to 75 parts of deionized water and ultrasonically disperse evenly. Add 1.5 parts of N,N-diethyl-2-oxiranecarboxamide and 0.4 part of potassium hydroxide, and stir at 40 °C for 2.5 h to obtain modified nano-silica;

[0043] Step 3: Preparation of base paper for paper tubes:

[0044] S1: Pulping, screening, and impurity removal of waste paper raw materials to obtain pulp grinding slurry;

[0045] S2: After centrifuging and dehydrating the pulp grinding slurry, prepare 100 parts of a slurry with a concentration of 1.5 wt%, add 1 part of starch granules, 0.1 part of dry strength agent, 0.3 part of water repellent, 0.05 part of modifier (0.01 part of modified polyacrylamide, 0.04 part of modified nano-silica), and disperse evenly by ultrasonic treatment to obtain pulp.

[0046] S3: Perform papermaking on the pulp, press for dehydration, dry at 100 °C, and calender to obtain the base paper for paper tubes.

[0047] Example 3: Step 1: Preparation of modified polyacrylamide: (1) Mix 90 parts of 40 wt% acrylamide aqueous solution, 0.3 part of N,N-bis(2-(2-oxiranylmethoxy)ethyl) acrylamide, and 0.35 part of sodium methallyl sulfonate evenly, add 9 parts of 30 wt% sulfuric acid and 6.7 parts of diethylaminoethyl methacrylate and stir evenly to obtain a reaction monomer solution.

[0048] (2) Add 0.07 part of disodium ethylenediaminetetraacetate to 110 parts of deionized water and stir evenly. Under a nitrogen atmosphere, heat to 90 °C, add 0.2 part of ammonium persulfate and stir evenly. Gradually add 115 parts of the reaction monomer solution, stir at 90 °C for 2.5 h, filter, and dry to obtain modified polyacrylamide.

[0049] Step 2: Preparation of modified nano-silica:

[0050] (1) Add 4 parts of nano-silica to 110 parts of 60% ethanol solution and disperse evenly by ultrasonic treatment. Add 2 parts of 3-aminopropyltriethoxysilane, stir at 55 °C for 50 min, filter, wash, and dry to obtain amino-modified nano-silica.

[0051] (2) Add 3 parts of amino-modified nano-silica to 75 parts of deionized water and disperse evenly by ultrasonic treatment. Add 1.5 parts of N,N-diethyl-2-(2-oxiranylmethoxy)acetamide and 0.4 part of potassium hydroxide, and stir at 40 °C for 2.5 h to obtain modified nano-silica.

[0052] Step 3: Preparation of the base paper for paper tubes:

[0053] S1: Pulverize, screen, and remove impurities from waste paper raw materials to obtain pulp grinding slurry.

[0054] S2: After centrifuging and dehydrating the pulp grinding slurry, prepare 100 parts of a slurry with a concentration of 2 wt%, add 1.5 parts of starch granules, 0.2 part of dry strength agent, 0.5 part of water repellent, 0.08 part of modifier (0.02 part of modified polyacrylamide, 0.06 part of modified nano-silica), and disperse evenly by ultrasonic treatment to obtain pulp.

[0055] S3: Perform papermaking on the pulp, press for dehydration, dry at 100 °C, and calender to obtain the base paper for paper tubes.

[0056] Comparative Example 1: Based on Example 1, N,N-bis(oxiran-2-ylmethyl)prop-2-enamide was not added during the preparation of the modified polyacrylamide, and the remaining processes remained unchanged. The details are as follows:

[0057] Step 1: Preparation of the modified polyacrylamide: (1) 90 parts of a 40 wt% acrylamide aqueous solution and 0.35 part of sodium methallylsulfonate were mixed evenly, 9 parts of 30 wt% sulfuric acid and 6.7 parts of diethylaminoethyl methacrylate were added and stirred evenly to obtain a reaction monomer solution;

[0058] (2) 0.07 part of disodium ethylenediaminetetraacetate was added to 110 parts of deionized water and stirred evenly. Under a nitrogen atmosphere, it was heated to 90 °C, 0.2 part of ammonium persulfate was added and stirred evenly. 115 parts of the reaction monomer solution were gradually added dropwise, and it was stirred at 90 °C for 2.5 h, filtered, and dried to obtain the modified polyacrylamide;

[0059] Step 2: Preparation of the modified nano-silica:

[0060] (1) 4 parts of nano-silica were added to 110 parts of a 60% ethanol solution and ultrasonically dispersed evenly. 2 parts of 3-aminopropyltriethoxysilane were added, and it was stirred at 55 °C for 50 min, filtered, washed, and dried to obtain amino-modified nano-silica;

[0061] (2) 3 parts of the amino-modified nano-silica were added to 75 parts of deionized water and ultrasonically dispersed evenly. 1.5 parts of N,N-diethyl-2-oxiranecarboxamide and 0.4 part of potassium hydroxide were added, and it was stirred at 40 °C for 2.5 h to obtain the modified nano-silica;

[0062] Step 3: Preparation of the base paper for paper tubes:

[0063] S1: The waste paper raw material was pulped, screened, and decontaminated to obtain a pulp grinding slurry;

[0064] S2: After the pulp grinding slurry was dewatered by centrifugation, it was formulated into 100 parts of a slurry with a concentration of 1.7 wt%. 1.2 parts of starch granules, 0.1 part of dry strength agent, 0.4 part of water repellent, 0.07 part of modifier (0.02 part of modified polyacrylamide, 0.05 part of modified nano-silica) were added and ultrasonically dispersed evenly to obtain pulp;

[0065] S3: The pulp was subjected to papermaking, press dewatering, drying at 100 °C, and calendering to obtain the base paper for paper tubes.

[0066] Comparative Example 2: Based on Example 1, the addition amount of N,N-bis(oxiran-2-ylmethyl)prop-2-enamide was increased during the preparation of the modified polyacrylamide, and the remaining processes remained unchanged. The details are as follows:

[0067] Step 1: Preparation of modified polyacrylamide: (1) Mix 90 parts of 40 wt% acrylamide aqueous solution, 1 part of N,N-bis(oxiran-2-ylmethyl)prop-2-enamide, and 0.35 part of sodium methallylsulfonate evenly, add 9 parts of 30 wt% sulfuric acid and 6.7 parts of diethylaminoethyl methacrylate and stir evenly to obtain a reaction monomer solution;

[0068] (2) Add 0.07 part of disodium ethylenediaminetetraacetate to 110 parts of deionized water and stir evenly. Under a nitrogen atmosphere, heat to 90 °C, add 0.2 part of ammonium persulfate and stir evenly. Gradually add 115 parts of the reaction monomer solution, stir at 90 °C for 2.5 h, filter, and dry to obtain modified polyacrylamide;

[0069] Step 2: Preparation of modified nano-silica:

[0070] (1) Add 4 parts of nano-silica to 110 parts of 60% ethanol solution and disperse evenly by ultrasonic wave. Add 2 parts of 3-aminopropyltriethoxysilane, stir at 55 °C for 50 min, filter, wash, and dry to obtain amino-modified nano-silica;

[0071] (2) Add 3 parts of amino-modified nano-silica to 75 parts of deionized water and disperse evenly by ultrasonic wave. Add 1.5 parts of N,N-diethyl-2-oxiranecarboxamide and 0.4 part of potassium hydroxide, stir at 40 °C for 2.5 h to obtain modified nano-silica;

[0072] Step 3: Preparation of paper tube base paper:

[0073] S1: Pulverize, screen, and remove impurities from waste paper raw materials to obtain pulp grinding slurry;

[0074] S2: After centrifuging the pulp grinding slurry to dryness, prepare 100 parts of slurry with a concentration of 1.7 wt%, add 1.2 parts of starch granules, 0.1 part of dry strength agent, 0.4 part of waterproof agent, 0.07 part of modifier (0.02 part of modified polyacrylamide, 0.05 part of modified nano-silica), and disperse evenly by ultrasonic wave to obtain pulp;

[0075] S3: Carry out papermaking treatment on the pulp, press for dehydration, dry at 100 °C, and calender to obtain paper tube base paper.

[0076] Comparative Example 3: Based on Example 1, without introducing modified nano-silica, and the rest of the processes remain unchanged. Specifically as follows:

[0077] Step 1: Preparation of modified polyacrylamide: (1) Mix 90 parts of 40 wt% acrylamide aqueous solution, 0.3 part of N,N-bis(oxiran-2-ylmethyl)prop-2-enamide, and 0.35 part of sodium methallylsulfonate uniformly, add 9 parts of 30 wt% sulfuric acid and 6.7 parts of diethylaminoethyl methacrylate and stir evenly to obtain a reaction monomer solution;

[0078] (2) Add 0.07 part of disodium ethylenediaminetetraacetate to 110 parts of deionized water and stir evenly. Under a nitrogen atmosphere, heat to 90 °C, add 0.2 part of ammonium persulfate and stir evenly. Gradually dropwise add 115 parts of the reaction monomer solution, stir at 90 °C for 2.5 h, filter, and dry to obtain modified polyacrylamide;

[0079] Step 2: Preparation of base paper for paper tubes:

[0080] S1: Pulverize, screen, and remove impurities from waste paper raw materials to obtain pulp grinding slurry;

[0081] S2: After dehydrating the pulp grinding slurry by centrifugation, prepare 100 parts of a slurry with a concentration of 1.7 wt%, add 1.2 parts of starch granules, 0.1 part of dry strength agent, 0.4 part of waterproof agent, 0.02 part of modifier (0.02 part of modified polyacrylamide), and disperse evenly by ultrasonic treatment to obtain pulp;

[0082] S3: Perform papermaking on the pulp, press and dehydrate, dry at 100 °C, and calender to obtain base paper for paper tubes.

[0083] Comparative Example 4: Based on Example 1, the nano-silica is not modified, and the rest of the process remains unchanged. Specifically as follows:

[0084] Step 1: Preparation of modified polyacrylamide: (1) Mix 90 parts of 40 wt% acrylamide aqueous solution, 0.3 part of N,N-bis(oxiran-2-ylmethyl)prop-2-enamide, and 0.35 part of sodium methallylsulfonate uniformly, add 9 parts of 30 wt% sulfuric acid and 6.7 parts of diethylaminoethyl methacrylate and stir evenly to obtain a reaction monomer solution;

[0085] (2) Add 0.07 part of disodium ethylenediaminetetraacetate to 110 parts of deionized water and stir evenly. Under a nitrogen atmosphere, heat to 90 °C, add 0.2 part of ammonium persulfate and stir evenly. Gradually dropwise add 115 parts of the reaction monomer solution, stir at 90 °C for 2.5 h, filter, and dry to obtain modified polyacrylamide;

[0086] Step 2: Preparation of base paper for paper tubes:

[0087] S1: Pulverize, screen, and remove impurities from waste paper raw materials to obtain pulp grinding slurry;

[0088] S2: After centrifuging and drying the ground pulp slurry, prepare 100 parts of pulp with a concentration of 1.7 wt%, add 1.2 parts of starch granules, 0.1 part of dry strength agent, 0.4 part of water repellent, and 0.07 part of modifier (0.02 part of modified polyacrylamide, 0.05 part of nano-silica), and disperse evenly by ultrasonic treatment to obtain pulp.

[0089] S3: Carry out papermaking treatment on the pulp, press for dehydration, dry at 100 °C, and calender to obtain the base paper for paper tubes.

[0090] Performance test: (1) Use an internal bond strength tester to test the internal bond strength of the base paper for paper tubes prepared in each example and comparative example according to GB / T 26203-2023. Measure each sample ten times and take the average value. The experimental data are shown in Table 1. (2) Use a bursting strength tester to test the bursting index of the base paper for paper tubes prepared in each example and comparative example according to GB / T 454-2020. Measure each sample ten times and take the average value. The experimental data are shown in Table 1.

[0091] Table 1

[0092]

[0093] Conclusion: As can be seen from Table 1, in Comparative Example 1, N,N-bis(2-(oxiran-2-yl)methyl)prop-2-enamide is not added, and the molecular weight of polyacrylamide is relatively low and its stability is poor, resulting in poor flocculation effect, thus reducing the internal bond strength and bursting index. In Comparative Example 2, the addition amount of N,N-bis(2-(oxiran-2-yl)methyl)prop-2-enamide is increased in the preparation of modified polyacrylamide, the molecular chain segment of polyacrylamide is too large and the crosslinking density is too high, which cannot be effectively dispersed in the pulp, resulting in poor flocculation effect, thus reducing the internal bond strength and bursting index. In Comparative Example 3, without introducing modified nano-silica, it is significantly inferior to Example 1. In Comparative Example 4, nano-silica is not modified, and its dispersibility in the system is poor, resulting in a decrease in the internal bond strength and bursting index.

[0094] In summary, by introducing modified polyacrylamide and modified nano-silica in the process of preparing the base paper for paper tubes, the present invention successfully provides a high-strength base paper for paper tubes and its preparation method, which has the characteristics of high internal bond strength and large bursting index.

[0095] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent substitution on some of the technical features. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A preparation method of high-strength base paper for paper tubes, characterized in that, It includes the following steps: S1: Pulping, screening, and impurity removal of waste paper raw materials to obtain pulp grinding slurry; S2: Adding starch particles, dry strength agent, waterproof agent, and modifier to the slurry prepared after centrifugal dehydration of the pulp grinding slurry, and ultrasonically dispersing evenly to obtain pulp; S3: Performing papermaking treatment on the pulp, pressing for dehydration, drying, and calendering to obtain base paper for paper tubes.

2. The preparation method of a high-strength paper tube base paper according to claim 1, characterized in that: In step S2, the concentration of the slurry prepared after centrifugal dehydration is 1.5 - 2 wt%.

3. The preparation method of a high-strength paper tube base paper according to claim 1, wherein: The pulp includes the following raw materials by mass: 100 parts of slurry, 1 - 1.5 parts of starch particles, 0.1 - 0.2 parts of dry strength agent, 0.3 - 0.5 parts of waterproof agent, 0.05 - 0.1 parts of modifier.

4. The preparation method of a high-strength base paper for paper tubes according to claim 1, characterized in that: The modifier includes the following raw materials by mass: 0.01 - 0.02 parts of modified polyacrylamide, 0.04 - 0.06 parts of modified nano - silica.

5. The preparation method of a high-strength paper tube base paper according to claim 4, characterized in that: The preparation method of the modified polyacrylamide includes the following steps: (1) Mix 40 wt% acrylamide aqueous solution, N,N - bis(oxiran - 2 - ylmethyl)prop - 2 - enamide, and sodium methallylsulfonate evenly, add 30 wt% sulfuric acid and diethylaminoethyl methacrylate and stir evenly to obtain a reaction monomer solution; (2) Add disodium ethylenediaminetetraacetate to deionized water and stir evenly. Under a nitrogen atmosphere, heat to 90 - 95 °C, add ammonium persulfate and stir evenly. Gradually dropwise add the reaction monomer solution, stir at 90 - 95 °C for 2 - 3 h, filter, and dry to obtain modified polyacrylamide.

6. The preparation method of a high-strength paper tube base paper according to claim 5, characterized in that: The reaction monomer solution includes the following raw materials by mass: 110 - 120 parts of 40 wt% acrylamide aqueous solution, 0.2 - 0.4 parts of N,N - bis(oxiran - 2 - ylmethyl)prop - 2 - enamide, 0.3 - 0.4 parts of sodium methallylsulfonate, 20 - 25 parts of deionized water, 8 - 10 parts of 30 wt% sulfuric acid, 6.5 - 7 parts of diethylaminoethyl methacrylate; The modified polyacrylamide includes the following raw materials by mass: 0.05 - 0.1 parts of disodium ethylenediaminetetraacetate, 100 - 120 parts of deionized water, 0.1 - 0.3 parts of ammonium persulfate, 110 - 120 parts of reaction monomer solution.

7. The preparation method of a high-strength base paper for paper tubes according to claim 4, characterized in that: The preparation method of the modified nano - silica includes the following steps: (1) Add nano - silica to 60% ethanol solution and ultrasonically disperse evenly. Add 3 - aminopropyltriethoxysilane and stir at 50 - 60 °C for 40 - 60 min, filter, wash, and dry to obtain amino - modified nano - silica; (2) Add the amino - modified nano - silica to deionized water and ultrasonically disperse evenly. Add N,N - diethyl - 2 - oxiranecarboxamide and potassium hydroxide and stir at 40 - 45 °C for 2 - 3 h to obtain modified nano - silica.

8. A method for preparing the base paper of a high-strength paper tube according to claim 7, characterized in that: The amino - modified nano - silica includes the following raw materials by mass: 3 - 5 parts of nano - silica, 100 - 120 parts of 60% ethanol solution, 1 - 3 parts of 3 - aminopropyltriethoxysilane; The modified nano-silica comprises the following raw materials in parts by mass: 2-4 parts of amino-modified nano-silica, 70-80 parts of deionized water, 1-2 parts of N,N-diethyl-2-oxazolidinone, and 0.3-0.5 part of potassium hydroxide.

9. The base paper for paper tubes prepared by the method for preparing a base paper for high-strength paper tubes according to any one of claims 1-8.

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