High-strength cultural paper and preparation method thereof

Abstract

The invention belongs to the technical field of culture paper production, and particularly relates to high-strength culture paper and a preparation method thereof. The preparation method of the high-strength cultural paper comprises the following steps: grinding pulp: grinding and crushing NBKP pulp, LBKP pulp and BCTMP pulp, and mixing to obtain mixed pulp; chemical addition: adding a dry strength agent, a filler, an internal sizing agent and an auxiliary agent into the mixed slurry, and uniformly stirring; a paper machine is adopted for continuous papermaking forming, squeezing, pre-baking, sizing, post-baking, calendaring and reeling are conducted, and the high-strength cultural paper is obtained. According to the high-strength cultural paper provided by the invention, the use amount of chemicals such as a dry strength agent is reduced by optimizing the slurry ratio, so that the strength of the cultural paper is improved while the production cost is reduced, and the product quality consistency is greatly improved; in addition, the invention also provides a preparation method, the preparation process is simple, and the production is smooth.

Description

Technical Field

[0001] This invention belongs to the field of cultural paper production technology, specifically relating to a high-strength cultural paper and its preparation method. Background Technology

[0002] As a core basic material in printing, office, and writing fields, the quality of cultural paper directly determines the downstream application experience. Paper strength, quality consistency, production cost, and production stability are key indicators for measuring production. Among cultural papers, offset paper and electrostatic copying paper, as the main carriers for daily office, printing, and writing, not only need to meet basic writing and printing compatibility, but also have more stringent requirements on the mechanical properties of paper such as tensile strength and bursting strength.

[0003] CN116145465A discloses a double-sided offset paper and its preparation method. The method involves pulping mechanical pulp, softwood chemical pulp, and hardwood chemical pulp in a mass ratio of 20-35:10-30:35-70, combined with fillers and additives. The pulping process includes refining, papermaking, surface sizing, and calendering to produce the double-sided offset paper. The paper achieves a high yield with a free mechanical pulp content of 180-300ml and a fiber bundle oversize ratio of ≤0.1%. The surface sizing layer uses a nano-cationic styrene acrylic emulsion and starch compound system. While maintaining high bulk, this method improves the paper's smoothness, opacity, and anti-bleed-through properties. It increases the proportion of mechanical pulp and fillers, reducing production costs. However, the increased amount of mechanical pulp and fillers leads to insufficient surface strength, making the paper prone to linting and powdering during printing.

[0004] In summary, existing cultural paper preparation technologies still have significant shortcomings in balancing production costs, paper mechanical properties, and surface quality. Therefore, developing a preparation technology that can reduce production costs while ensuring paper mechanical properties, surface quality, and production stability has important practical significance and industrial value. Summary of the Invention

[0005] To overcome the aforementioned deficiencies in the existing technology, this invention provides high-strength cultural paper. By optimizing the pulp ratio, the amount of chemicals such as dry strength agents is reduced, thereby reducing production costs while improving the strength of the cultural paper and significantly enhancing product quality consistency. Furthermore, this invention also provides a preparation method for it, which is simple to prepare and allows for smooth production.

[0006] A method for preparing high-strength cultural paper includes the following steps: (1) Pulping: After the NBKP pulp board and LBKP pulp board are broken down by a hydraulic pulper, they are ground with BCTMP wet pulp in a multi-stage cone mill. After grinding, the three pulps are mixed to obtain a mixed pulp. (2) Adding chemicals: Add dry strength agent, filler, slurry sizing agent and additives to the mixed slurry and stir evenly; (3) Online forming: The paper machine is used for continuous papermaking, and the paper is pressed, pre-dryed, sized, post-dryed, calendered and wound to obtain high-strength cultural paper.

[0007] In the mixed slurry, the proportions of the three slurries by mass percentage are: NBKP 18-23 wt.%, LBKP 49-57 wt.%, and BCTMP 25-28 wt.%.

[0008] During the pulping process, the pulping concentrations of the three pulps are controlled as follows: NBKP pulp 3.9-4.5 wt.%, LBKP pulp 4.7-5.3 wt.%, and BCTMP pulp 3.7-4.3 wt.%.

[0009] The freeness of each slurry after refining is controlled as follows: NBKP slurry 290-310mL, LBKP slurry 330-350mL, and BCTMP slurry 230-250mL.

[0010] The dry strength agent is a cationic dry strength agent with a viscosity of 500-3000 mPa·s. It is preferably one or more of POLYSTRONCH-1600, POLYSTRONCH-1700, POLYSTRONCH-3100, and POLYSTRONCH-3200 from Nantong Arakawa Chemical Industry Co., Ltd., and more preferably POLYSTRONCH-1700 with a solid content of 20 wt.%.

[0011] The dry strength agent is added at a rate of 4-8 kg / ton of paper, based on the total mass of all components. Preferably, it is added after being diluted 10-15 times with water.

[0012] The filler is a mixture of heavy calcium carbonate and light calcium carbonate, and the amount of filler added is 250-270 kg / ton of paper. Preferably, the mass ratio of heavy calcium carbonate to light calcium carbonate is 7:3.

[0013] The sizing agent in the pulp is alkenyl succinic anhydride, and the addition amount is 1.0-1.3 kg / ton of paper, preferably 1.0 kg / ton of paper.

[0014] The additives are retention additives and color-correcting additives.

[0015] The retention aid is silica sol, and the color-matching aid is fluorescent whitening agent and dye / pigment color matching agent. The silica sol addition amount is 4-6 kg / ton of paper, preferably 4 kg / ton of paper. Further, the fluorescent whitening agent is divided into disulfonic acid fluorescent whitening agent added in the pulp in step (2) and hexasulfonic acid fluorescent whitening agent added in the surface sizing section in step (3). The two can be used at the same time. The amount of disulfonic acid fluorescent whitening agent is 4-8 kg / ton of paper, and the amount of hexasulfonic acid fluorescent whitening agent is 8-12 kg / ton of paper. The addition of dye / pigment color matching agent needs to be adjusted according to the color of the finished paper. Blue pigment, purple pigment, etc. can be added.

[0016] Furthermore, pressing, pre-drying, post-drying, calendering, and winding are all carried out according to conventional cultural paper production processes. Surface sizing uses corn starch: corn starch is prepared into a 20wt.% starch slurry, stirred evenly, then treated with a corn starch pretreatment agent for protein inhibition and pH adjustment, followed by enzymatic hydrolysis with amylase, and finally cooked at 135℃, simultaneously achieving enzyme inactivation and starch gelatinization. Hexasulfonic acid fluorescent whitening agent is added to the system at a rate of 10kg / ton of paper. When using, the solid content is adjusted to 12-13wt.%, and the paper is filtered before use. During surface sizing, the sizing machine linear pressure is 32.5±2.5kN / m, with double-sided sizing, using a film transfer sizing method to ensure a sizing amount of 1.2-1.5g / m on both sides. 2 .

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The high-strength cultural paper of the present invention reduces the amount of chemicals such as dry strength agent by optimizing the pulp ratio. While reducing production costs, the paper strength is significantly improved, the index fluctuation is small, and the product quality consistency is greatly improved.

[0018] (2) The high-strength cultural paper of the present invention uses a low-viscosity, low-addition cationic dry strength agent, which effectively improves the filtration speed and solves the problem of poor filtration during process scale-up; the paper breakage rate of the machine is significantly reduced, the production smoothness is significantly improved, and downtime losses are reduced.

[0019] (3) The preparation method of the high-strength cultural paper of the present invention is simple and has strong continuity. Detailed Implementation

[0020] The technical solution of the present invention will be further described below with reference to the embodiments and comparative examples. Unless otherwise specified, the raw materials used in the embodiments and comparative examples are all conventional commercial raw materials, and the process methods used are all conventional methods in the art unless otherwise specified.

[0021] In the following examples and comparative examples, some raw materials and steps are described below: The color-matching additives are all applied in the pulp, including disulfonic acid fluorescent whitening agent, blue pigment and purple pigment. The amount of disulfonic acid fluorescent whitening agent added is 4 kg / ton of paper, blue pigment is 80 g / ton of paper and purple pigment is 160 g / ton of paper. When using a paper machine for continuous papermaking, the basis weight is controlled to be 80 g / m³. 2 The surface sizing uses corn starch, and hexasulfonic acid fluorescent whitening agent is added simultaneously to the surface sizing system at a rate of 10 kg / ton of paper. During use, the solid content is adjusted to 13 wt.%, and the paper is filtered through a 200-mesh sieve. The sizing machine has a linear pressure of 32.5 ± 2.5 kN / m, and double-sided sizing is performed using a film transfer sizing method to ensure that the sizing amount on both sides is 1.4 g / m². 2 .

[0022] The method for preparing the high-strength cultural paper includes the following steps: (1) Pulping: After the NBKP pulp board and LBKP pulp board are broken down by a hydraulic pulper, they are then subjected to multi-stage conical milling with BCTMP wet pulp. During the pulping process, the pulping concentrations of the three pulps are controlled as follows: NBKP pulp 3.9-4.5 wt.%, LBKP pulp 4.7-5.3 wt.%, BCTMP pulp 3.7-4.3 wt.%. After pulping, the freeness of each pulp is controlled as follows: NBKP pulp 290-310 mL, LBKP pulp 330-350 mL, BCTMP pulp 230-250 mL. After the pulping is completed, the three pulps are mixed to obtain a mixed pulp. The ratio of the three pulps by mass percentage is: NBKP pulp 18-23 wt.%, LBKP pulp 49-57 wt.%, BCTMP pulp 25-28 wt.%. (2) Adding chemicals: Add diluted cationic dry strength agent, calcium carbonate filler mixture, sizing agent alkenyl succinic anhydride, retention aid silica sol, color-matching aid fluorescent whitening agent, and dye / pigment colorant to the mixed slurry, and stir evenly; (3) Paper forming: Continuous paper forming is carried out using a paper machine, and the basis weight is controlled at 80g / m². 2 Care should be taken to control the filtration speed to ensure the uniformity of the fibers. Then, pressing, pre-drying, sizing, post-drying, calendering, and winding are carried out to obtain high-strength cultural paper.

[0023] Example 1 The method for preparing the high-strength cultural paper includes the following steps: (1) Pulping: After the NBKP pulp board and LBKP pulp board are broken down by a hydraulic pulper, they are then subjected to multi-stage conical milling with BCTMP wet pulp. During the pulping process, the pulping concentrations of the three pulps are controlled as follows: NBKP pulp 3.9 wt.%, LBKP pulp 5.0 wt.%, BCTMP pulp 3.7 wt.%. After pulping, the freeness of each pulp is controlled as follows: NBKP pulp 290 mL, LBKP pulp 340 mL, BCTMP pulp 230 mL. After the pulping is completed, the three pulps are mixed to obtain a mixed pulp. The ratio of the three pulps by mass percentage is: NBKP pulp 18 wt.%, LBKP pulp 57 wt.%, BCTMP pulp 25 wt.%. (2) Adding chemicals: Add the cationic dry strength agent POLYSTRONCH-1700 diluted 10 times, the filler calcium carbonate mixture, the pulp sizing agent alkenyl succinic anhydride, the retention aid silica sol, the color-matching aid fluorescent whitening agent, and the dye / pigment color-matching agent to the mixed pulp, and stir evenly; the addition amount of POLYSTRONCH-1700 is 4 kg / ton of paper, the filler calcium carbonate mixture is 250 kg / ton of paper, the pulp sizing agent alkenyl succinic anhydride is 1.0 kg / ton of paper, the retention aid silica sol is 4 kg / ton of paper, the disulfonic acid fluorescent whitening agent is 4 kg / ton of paper, the blue pigment is 80 g / ton of paper, and the purple pigment is 160 g / ton of paper; (3) Paper forming: The paper machine is used for continuous paper forming. The water filtration speed is controlled to ensure the uniformity of the fibers. Then, the paper is pressed, pre-dryed, sized, post-dryed, calendered, and wound to obtain high-strength cultural paper.

[0024] Example 2 The method for preparing the high-strength cultural paper includes the following steps: (1) Pulping: After the NBKP pulp board and LBKP pulp board are broken down by a hydraulic pulper, they are then subjected to multi-stage conical milling with BCTMP wet pulp. During the pulping process, the pulping concentrations of the three pulps are controlled as follows: NBKP pulp 4.5 wt.%, LBKP pulp 5.3 wt.%, BCTMP pulp 4.0 wt.%. After pulping, the freeness of each pulp is controlled as follows: NBKP pulp 300 mL, LBKP pulp 330 mL, BCTMP pulp 240 mL. After the pulping is completed, the three pulps are mixed to obtain a mixed pulp. The ratio of the three pulps by mass percentage is: NBKP pulp 23 wt.%, LBKP pulp 49 wt.%, BCTMP pulp 28 wt.%. (2) Addition of chemicals: Add the cationic dry strength agent POLYSTRONCH-1700 diluted 13 times, the filler calcium carbonate mixture, the pulp sizing agent alkenyl succinic anhydride, the retention aid silica sol, the color-matching aid fluorescent whitening agent, and the dye / pigment colorant to the mixed pulp, and stir evenly; the addition amount of POLYSTRONCH-1700 is 6 kg / ton of paper, the filler calcium carbonate mixture is 260 kg / ton of paper, the pulp sizing agent alkenyl succinic anhydride is 1.0 kg / ton of paper, the retention aid silica sol is 4 kg / ton of paper, the disulfonic acid fluorescent whitening agent is 4 kg / ton of paper, the blue pigment is 80 g / ton of paper, and the purple pigment is 160 g / ton of paper; (3) Paper forming: The paper machine is used for continuous paper forming. The water filtration speed is controlled to ensure the uniformity of the fibers. Then, the paper is pressed, pre-dryed, sized, post-dryed, calendered, and wound to obtain high-strength cultural paper.

[0025] Example 3 The method for preparing the high-strength cultural paper includes the following steps: (1) Pulping: After the NBKP pulp board and LBKP pulp board are broken down by a hydraulic pulper, they are then subjected to multi-stage conical milling with BCTMP wet pulp. During the pulping process, the pulping concentrations of the three pulps are controlled as follows: NBKP pulp 4.3 wt.%, LBKP pulp 4.7 wt.%, and BCTMP pulp 4.3 wt.%. After pulping, the freeness of each pulp is controlled as follows: NBKP pulp 310 mL, LBKP pulp 350 mL, and BCTMP pulp 250 mL. After the pulping is completed, the three pulps are mixed to obtain a mixed pulp. The ratio of the three pulps by mass percentage is: NBKP pulp 20 wt.%, LBKP pulp 53 wt.%, and BCTMP pulp 27 wt.%. (2) Addition of chemicals: Add the cationic dry strength agent POLYSTRONCH-1700 diluted 15 times, the filler calcium carbonate mixture, the pulp sizing agent alkenyl succinic anhydride, the retention aid silica sol, the color-matching aid fluorescent whitening agent, and the dye / pigment colorant to the mixed pulp, and stir evenly; the addition amount of POLYSTRONCH-1700 is 8 kg / ton of paper, the filler calcium carbonate mixture is 270 kg / ton of paper, the pulp sizing agent alkenyl succinic anhydride is 1.0 kg / ton of paper, the retention aid silica sol is 4 kg / ton of paper, the disulfonic acid fluorescent whitening agent is 4 kg / ton of paper, the blue pigment is 80 g / ton of paper, and the purple pigment is 160 g / ton of paper; (3) Paper forming: The paper machine is used for continuous paper forming. The water filtration speed is controlled to ensure the uniformity of the fibers. Then, the paper is pressed, pre-dryed, sized, post-dryed, calendered, and wound to obtain high-strength cultural paper.

[0026] Comparative Example 1 This comparative example is the same as Example 2, except that the ratio of the three pulps in the mixed pulp in step (1) is adjusted. By mass percentage, NBKP pulp is 20wt.%, LBKP pulp is 50wt.%, and BCTMP pulp is 30wt.%. The remaining steps are the same as in Example 2.

[0027] Comparative Example 2 This comparative example is the same as Example 2, except that the degree of freeness of each slurry after grinding in step (1) is adjusted to: 300 mL of NBKP slurry, 330 mL of LBKP slurry, and 260 mL of BCTMP slurry. The remaining steps are the same as in Example 2.

[0028] The cultural papers prepared in Examples 1-3 and Comparative Examples 1-2 were subjected to performance tests. The interlayer bonding strength was tested according to standard GB / T26203-2023, and the tensile index was tested according to standard GB / T 12914-2018. The test results are shown in Table 1.

[0029] Table 1 Product Performance Test Results

[0030] As shown in Table 1, the preparation method of this embodiment, by controlling the pulp ratio, refining parameters, and additive dosage, produces cultural paper with excellent performance in terms of interlayer bond strength, tensile index, and transverse folding endurance: interlayer bond strength ≥226J / m. 2 Tensile index ≥69.7 N·m / g.

Claims

1. A method for preparing high-strength cultural paper, characterized in that, Includes the following steps: (1) Pulping: After the NBKP pulp board and LBKP pulp board are broken down by a hydraulic pulper, they are ground with BCTMP wet pulp in a multi-stage cone mill. After grinding, the three pulps are mixed to obtain a mixed pulp. (2) Adding chemicals: Add dry strength agent, filler, slurry sizing agent and additives to the mixed slurry and stir evenly; (3) Online forming: The paper machine is used for continuous papermaking, which involves pressing, pre-drying, sizing, post-drying, calendering, and winding to obtain high-strength cultural paper; In the mixed pulp, the proportions of the three pulps by mass percentage are: NBKP pulp 18-23 wt.%, LBKP pulp 49-57 wt.%, and BCTMP pulp 25-28 wt.%; the freeness of each pulp after refining is controlled as follows: NBKP pulp 290-310 mL, LBKP pulp 330-350 mL, and BCTMP pulp 230-250 mL.

2. The method for preparing high-strength cultural paper according to claim 1, characterized in that, During the pulping process, the pulping concentrations of the three pulps are controlled as follows: NBKP pulp 3.9-4.5 wt.%, LBKP pulp 4.7-5.3 wt.%, and BCTMP pulp 3.7-4.3 wt.%.

3. The method for preparing high-strength cultural paper according to claim 1, characterized in that, The dry strength agent is a cationic dry strength agent with a viscosity of 500-3000 mPa·s, and the addition amount of the dry strength agent is 4-8 kg / ton of paper.

4. The method for preparing high-strength cultural paper according to claim 1, characterized in that, The filler is a mixture of heavy calcium carbonate and light calcium carbonate, and the amount of filler added is 250-270 kg / ton of paper.

5. The method for preparing high-strength cultural paper according to claim 1, characterized in that, The sizing agent used in the pulp is alkenyl succinic anhydride, and the addition amount is 1.0-1.3 kg / ton of paper.

6. The method for preparing high-strength cultural paper according to claim 1, characterized in that, The additives are retention additives and color-correcting additives.

7. The method for preparing high-strength cultural paper according to claim 6, characterized in that, The retention aid is silica sol, and the amount of silica sol added is 4-6 kg / ton of paper; the color-matching aid is fluorescent whitening agent and dye / pigment colorant.

8. A high-strength cultural paper, characterized in that, It is prepared by the preparation method described in any one of claims 1-7.

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