Method for preparing high-strength corrugating medium from semi-chemical pulp

Abstract

The invention provides a method for preparing high-strength corrugated base paper from semi-chemical pulp, which comprises the following steps: S1, preparing the semi-chemical pulp: circularly cooking a fiber raw material in a vertical cooker by using cooking liquor to obtain the semi-chemical pulp with lignin and sugar molecules attached to the fiber surface; s2, preparing pulp of the high-strength corrugating base paper from the semi-chemical pulp, wherein the pulp of the high-strength corrugating base paper is prepared from the following components in percentage by mass: 25.0 percent to 35.0 percent of the semi-chemical pulp, 64.962 percent to 74.96 percent of the recycled paper pulp, 0.018 percent to 0.02 percent of a fatty alcohol defoaming agent and 0.02 percent to 0.022 percent of polyacrylamide. The semi-chemical pulp with a special structure that lignin and sugar molecules are attached to the surface of the fiber is prepared and used as a core component to prepare the high-strength corrugating base paper, a part of black liquor is recycled during production, energy consumption for evaporating and concentrating the part of black liquor is reduced, and the production cost is reduced. Meanwhile, the use amount of a reinforcing agent needed for producing the high-strength corrugating base paper is reduced, and compared with conventional chemimechanical pulp, the energy consumption needed for disc grinding of cork chips is reduced by about 35.41%.

Description

Technical Field

[0001] The present application relates to the technical field of pulping and papermaking, and in particular to a method for preparing high-strength corrugated base paper using semi-chemical pulp. Background Art

[0002] As a commonly used fiber material, pulp is in high demand. In 2023, the domestic pulp production will be about 27.5 million tons, and the pulp consumption will be about 53.2 million tons; among them, the corrugated paper production will be about 28 million tons, and the corrugated paper production and consumption will be about 31.4 million tons, an increase of about 4% year-on-year. Corrugated paper has the advantages of low cost, light weight, easy processing, high strength, excellent printing adaptability, convenient storage and transportation, and easy recycling. It is widely used as a packaging material for food or digital products. Especially today when online shopping platforms are well developed, the demand for corrugated paper as a packaging material is increasing year by year.

[0003] As the demand for corrugated paper increases, the output and import of corrugated paper will also increase. Therefore, it is necessary to pay more attention to the quality of corrugated paper and its influencing factors, produce higher quality corrugated paper products, and reduce resource waste. From the process system of pulping and papermaking, it can be seen that the quality of paper is directly related to the pulp. Therefore, in the process of producing corrugated paper, the selection of fiber raw materials, the optimization of pulping process, the proportion of pulp and the additives (fillers) added will cause the performance of the final product to change.

[0004] my country issued and implemented the first standard for corrugated paper in 1991, and updated the standard in 2008 to ensure high quality requirements for corrugated paper. In the current "GB / T13023-2008 Corrugated Core (Base) Paper", the quality grade of corrugated base paper is mainly determined by indicators such as density, transverse ring pressure index, flat pressure index, and longitudinal tear length; among them, the highest quality corrugated base paper - AAA grade superior product, has the following standard requirements: density ≥ 0.55g / cm3, transverse ring pressure index ≥ 7.5N·m / g, 8.5N·m / g, 10.0N·m / g, 11.5N·m / g (corresponding to quantitative ≤ 90g / m2, 90g / m2~140g / m2, 140g / m2~180g / m2, ≥180g / m2), flat pressure index ≥ 1.40Nm2 / g, and longitudinal tear length ≥ 5.00km. Summary of the invention

[0005] The main purpose of the present application is to provide a method for producing high-strength corrugated paper with semi-chemical pulp prepared by circulating cooking of black liquor as a key component, aiming to solve the technical problem of improving the strength of corrugated paper.

[0006] This application is implemented through the following technical solutions:

[0007] The present application proposes a method for preparing high-strength corrugated paper using semi-chemical pulp, comprising the following steps:

[0008] Step S1, preparing semi-chemical pulp, using cooking liquid to circulate and cook fiber raw materials in a vertical digester to obtain semi-chemical pulp with lignin and sugar molecules attached to the fiber surface;

[0009] Step S2, preparing a pulping material of high-strength corrugated base paper with semi-chemical pulp, wherein the proportion of each component of the pulping material of high-strength corrugated base paper in terms of mass percentage is:

[0010]

[0011] Step S3, using a Fourdrinier paper machine to make high-strength corrugated paper, and mixing the alkyl ketene dimer into the slurry during the making process.

[0012] Furthermore, the proportions of the components of the cooking liquid used in step S1 are as follows in terms of mass percentage:

[0013] Black liquor 50.0%-70.0%

[0014] Sodium hydroxide 11.5%-14.5%

[0015] Sodium carbonate 2.5%-3.5%.

[0016] Furthermore, the cooking temperature in the vertical cooker is 140° C.-170° C., and the cooking time is 3 h to 4 h.

[0017] Furthermore, the heating process of the vertical cooker is to first heat the temperature to 140°C-145°C and keep it for 1 hour, then heat the temperature to 155°C and keep it for 1 hour, and finally heat the temperature to 165°C-170°C and keep it for 1-2 hours.

[0018] Furthermore, in step S1, the fiber pulp after the circulating cooking is completed needs to be reversely washed five times in the pulp washing tank, and the washed fiber pulp is subjected to triple refining to obtain semi-chemical pulp, the beating degree of the semi-chemical pulp is 21°SR-23°SR, and the black liquor after the circulating cooking and the pulping wastewater generated by the first reverse pulping are re-added to the vertical digester after alkali recovery treatment.

[0019] Furthermore, in the step S2, the pulping of the high-strength corrugated base paper is prepared in a pulping tank, and a stirrer is provided in the pulping tank. During pulping, the semi-chemical pulp and the recycled pulp are first added to the pulping tank for stirring, and then 0.018%-0.02% fatty alcohol defoamer and 0.02%-0.022% polyacrylamide are added according to the total mass of the mixed pulp, and the pulping is fully mixed again to complete the pulping.

[0020] Furthermore, the beating degree of the recovered pulp is 23°SR-24°SR.

[0021] Furthermore, in the papermaking process of step S3, 42kg-45kg of starch solution and 2kg of alkyl ketene dimer are mixed into each ton of slurry.

[0022] Furthermore, when the fourdrinier papermaking machine is used for papermaking, the steam pressure is 0.3MPa-0.4MPa, the operating speed is 350m / min-400m / min, the drying temperature is 80℃-160℃, and the width of the high-strength corrugated paper is 4.0m-4.5m and the basis weight is 120g / m2-140g / m2.

[0023] Furthermore, the starch solution is prepared by mixing 98%-99% starch and 1%-2% ammonium persulfate, cooking at 95° C. for 60 min-70 min, and then keeping warm for 10 min to obtain the starch solution.

[0024] The beneficial effects of the present application are as follows: by preparing a semi-chemical pulp with a special structure in which lignin and sugar molecules are attached to the fiber surface, and using it as the core component to prepare high-strength corrugated paper, a portion of the black liquor is recycled during production, thereby reducing the energy consumption of evaporating and concentrating this portion of the black liquor, and at the same time reducing the amount of reinforcing agent required for the production of high-strength corrugated paper. Compared with conventional chemical mechanical pulp, the energy consumption required for disc grinding of cork chips is reduced by about 35.41%. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A production process flow chart of a method for preparing high-strength corrugated paper using semi-chemical pulp;

[0026] Figure 2 This is the quality diagram of high-strength corrugated paper products. DETAILED DESCRIPTION

[0027] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application, wherein the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0028] It should be noted that all directional indications in the embodiments of the present application (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0029] In addition, the descriptions of "first", "second", etc. in this application are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in this field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0030] like Figure 1 , Figure 2 As shown, Embodiment 1 of the present invention provides a method for preparing high-strength corrugated paper using semi-chemical pulp, comprising the following steps:

[0031] Step S1, preparing semi-chemical pulp, using cooking liquid to circulate and cook fiber raw materials in a vertical digester to obtain semi-chemical pulp with lignin and sugar molecules attached to the fiber surface; mainly using black liquor to circulate and cook wood chips or other fiber raw materials to obtain pulp with a special structure with lignin and sugar molecules attached to the fiber surface.

[0032] During the cooking process, under the catalytic action of alkali, lignin and newly generated cellulose pulp fibers undergo dehydration condensation polymerization reaction to produce grafted polymers. In addition, the soluble sugar molecules and fine fibers in the black liquor can also undergo grafted dehydration condensation reaction with the new cellulose pulp produced during the cooking process to produce pulp with a special structure in which sugar molecules and fine fibers are attached to the surface. After five reverse washings, semi-chemical pulp with a special structure is obtained.

[0033] Step S2, preparing a pulping material of high-strength corrugated base paper with semi-chemical pulp, wherein the proportion of each component of the pulping material of high-strength corrugated base paper in terms of mass percentage is:

[0034]

[0035] Pulping process: First, 25.0%-35.0% semi-chemical pulp with a special structure and 64.962%-74.96% recycled pulp are mixed, and mixed evenly by spiral stirring in the pulping tank; then, 0.018%-0.02% fatty alcohol defoamer and 0.02% polyacrylamide are added according to the total mass of the mixed pulp, and the pulping is fully mixed again to complete the pulping. By mixing the semi-chemical pulp and waste paper pulp, different fiber raw materials are matched with each other to improve the physical properties and increase the output of corrugated paper.

[0036] Step S3, using a Fourdrinier paper machine to make high-strength corrugated paper, and mixing alkyl ketene dimer into the slurry during the making process. In the process of making corrugated paper, starch and alkyl ketene dimer need to be added to the mixed slurry to achieve the purpose of improving paper strength and preventing paper breakage, thereby ultimately improving the quality of corrugated paper.

[0037] The essential reasons why the semi-chemical pulp with special structure in the present invention can improve the strength of corrugated base paper are as follows:

[0038] (1) Compared with conventional chemical pulp, semi-chemical pulp with a special structure has the same bonding properties as chemical pulp, and has a higher tensile index and breaking length; at the same time, after structural modification by the attachment of lignin and sugar molecules, the semi-chemical pulp has a higher hardness, overcoming the disadvantage of a low ring crush index in papermaking with conventional chemical pulp.

[0039] (2) Compared with conventional chemical mechanical pulp, semi-chemical pulp with special structure has stronger bonding force, so it has better bonding force when mixed with recycled pulp; at the same time, it maintains a similar tightness to chemical mechanical pulp. Therefore, the strength of corrugated paper produced using semi-chemical pulp with special structure as the key component is greater.

[0040] Preferably, the proportions of the components of the cooking liquid used in step S1 are as follows in terms of mass percentage:

[0041] Black liquor 50.0%-70.0%

[0042] Sodium hydroxide 11.5%-14.5%

[0043] Sodium carbonate 2.5%-3.5%.

[0044] 50.0%-70.0% of the cooking liquor is supplemented with black liquor, the sodium hydroxide content is 11.5%-14.5%, and the sodium carbonate content is 2.5%-3.5%. The sodium hydroxide and sodium carbonate are all derived from the recovered alkali liquor, which improves the utilization rate of sodium hydroxide and sodium carbonate and reduces the production cost.

[0045] Preferably, the cooking temperature in the vertical cooker is 140° C.-170° C., and the cooking time is 3 h to 4 h.

[0046] Specifically, the vertical digester's heating process is to first heat to 140℃145℃ and keep it for 1h, then heat to 155℃ and keep it for 1h, and finally heat to 165℃-170℃ and keep it for 1-2h. During the cooking process, under the catalytic action of alkali, lignin and newly generated cellulose pulp fibers undergo dehydration condensation polymerization reaction to produce grafted polymers. In addition, the soluble sugar molecules and fine fibers in the black liquor can also undergo grafted dehydration condensation reaction with the new cellulose pulp generated during the cooking process, producing pulp with a special structure with sugar molecules and fine fibers attached to the surface.

[0047] Preferably, in step S1, the fiber pulp after the circulation cooking is completed needs to be reversely washed five times in the pulp washing tank, and the washed fiber pulp is subjected to triple pulping to obtain semi-chemical pulp, and the beating degree of the semi-chemical pulp is 21°SR-23°SR. The black liquor after the circulation cooking is completed and the pulp washing wastewater generated by the first reverse pulp washing are re-added to the vertical digester after alkali recovery treatment, and a part of the black liquor is recycled to reduce the energy consumption of evaporating and concentrating this part of the black liquor, while avoiding the loss of fibers in the pulp washing wastewater generated by the first reverse pulp washing. Figure 2 As shown, after the recycling of black liquor, the various indicators of corrugated paper remain stable.

[0048] Furthermore, in step S2, the pulping of high-strength corrugated base paper is prepared in a pulping tank, and a stirrer is provided in the pulping tank. During pulping, semi-chemical pulp and recycled pulp are first added to the pulping tank for stirring, and then 0.018%-0.02% fatty alcohol defoamer and 0.02%-0.022% polyacrylamide are added according to the total mass of the mixed pulp, and the pulping is fully mixed again to complete the pulping, so that the semi-chemical pulp and recycled pulp are fully and evenly mixed to form the pulping of high-strength corrugated base paper. The semi-chemical pulp with a special structure has stronger bonding force, so it has better bonding force after mixing with the recycled pulp.

[0049] Specifically, the beating degree of recycled pulp is 23°SR-24°SR. By utilizing the strong bonding strength of semi-chemical pulp, it can be combined with recycled pulp to form high-strength corrugated paper, thereby ensuring the quality of corrugated paper while reducing the production cost of the product.

[0050] Furthermore, in step S3, during the papermaking process, 42kg-45kg of starch solution and 2kg of alkyl ketene dimer are mixed into each ton of pulp to achieve the purpose of improving paper strength and preventing paper breakage, thereby ultimately improving the quality of corrugated paper.

[0051] Furthermore, when the fourdrinier papermaking machine is used for papermaking, the steam pressure is 0.3MPa-0.4MPa, the operating speed is 350m / min-400m / min, the drying temperature is 80℃-160℃, and through appropriate process parameters, high-strength corrugated paper is produced. The width of the high-strength corrugated paper is 4.0m-4.5m and the basis weight is 120g / m2-140g / m2.

[0052] Specifically, the starch solution is prepared by mixing 98%-99% starch and 1%-2% ammonium persulfate, cooking at 95°C for 60min-70min, and then keeping warm for 10min to obtain a starch solution, and adding the starch solution and alkyl ketene dimer into the mixed slurry to achieve the purpose of improving paper strength and preventing paper breakage, thereby ultimately improving the quality of corrugated paper.

[0053] Taking the daily cooking of 300t of bone-dry eucalyptus as an example, this implementation uses 14% alkali and 25% semi-chemical pulp, and the specific steps are as follows:

[0054] 1. Preparation of semi-chemical pulp with special structure.

[0055] 418 tons (moisture content 28.23%, absolute dryness 300 tons) of eucalyptus raw materials were cut into wood chips of suitable thickness and size by a slicer;

[0056] Then the wood chips are cooked and pulped. The cooking method is: the mass ratio of absolute dry wood chips and cooking liquid is 1:2.8, that is, 300t absolute dry eucalyptus chips (moisture content 28.23%) require 840t cooking liquid. The eucalyptus chips contain 118t of water, and the 14% alkali amount requires 210t of recovered alkali solution (concentration 20%, providing 42t of sodium hydroxide required for cooking and 9.8t of residual sodium carbonate), which provides 158.2t of water, and the remaining 563.8t of cooking liquid is provided by 640.68t of black liquor (solid content 12%); the three-stage heating process of the cooking process is: first heat to 145℃ and keep warm for 1h, then heat to 155℃ and keep warm for 1h, and finally heat to 165℃ and keep warm for 1h. After cooking, 190.8t of semi-chemical coarse pulp with a special structure is obtained, and the pulp yield is 63.60%;

[0057] After five reverse washing processes for the raw pulp and triple refining, 190.8 tons of semi-chemical pulp with a special structure of 21°SR-23°SR was obtained; 385.7 tons of washing water was required for each washing process.

[0058] 2. Prepare the slurry.

[0059] Pulp formulation: 190.8t of semi-chemical pulp with special structure is the key and core component, and 572.4t of recycled pulp (beating degree 23°SR-24°SR), 152.64kg of fatty alcohol defoamer and 152.64kg of polyacrylamide are added.

[0060] Pulping process: First, 190.8t of semi-chemical pulp with a special structure (25% of the pulp) and 572.4t of recycled pulp are mixed and evenly mixed by spiral stirring in the pulping tank; then, 152.64kg of fatty alcohol defoamer and 152.64kg of polyacrylamide are added in sequence according to the total mass of the mixed pulp, and the pulping is fully mixed again to complete the pulping.

[0061] 3. Production of high-strength corrugated paper.

[0062] The prepared slurry is sent to the Fourdrinier through a power screen. During the papermaking process, 34.34 tons of starch solution (34.00 tons of starch and 0.34 tons of ammonium persulfate are cooked at 95°C) and 1.53 tons of alkyl ketene dimer are mixed into the prepared slurry. The steam pressure is 0.3MPa-0.4MPa, the operating speed is 390m / min and the drying temperature is 80°C-160°C (48 cylinders) to produce about 799.07 tons of high-strength corrugated paper with a width of 4.5m and a basis weight of 130g / m2.

[0063] 4. Product quality test results

[0064] The sampled products were tested and their main properties, including tensile index of 51.94N·m / g, tear length of 5.3km, ring pressure index of 8.56N·m / g and compactness of 0.56g·cm3, were better than the standard requirements of GB / T13023-2008 Corrugated Core (Base) Paper, which stipulates that the tensile index is not less than 49.00N·m / g, the tear length is not less than 5.00km, the ring pressure index is not less than 8.5N·m / g and the compactness is not less than 0.55g·cm3. Therefore, the corrugated base paper products meet the AAA grade requirements of the standard.

[0065] Embodiment 2

[0066] Taking the daily cooking of 300t of bone-dry eucalyptus as an example, this implementation uses 12% alkali and 25% semi-chemical pulp, and the specific steps are as follows:

[0067] 1. Preparation of semi-chemical pulp with special structure.

[0068] 418t (moisture content 28.23%, absolute dryness 300t) of eucalyptus raw material was cut into wood chips of suitable thickness and size by a slicer.

[0069] Then the wood chips are cooked and pulped. The cooking method is: the mass ratio of absolute dry wood chips to cooking liquid is 1:2.8, that is, 300t absolute dry eucalyptus chips (moisture content 28.23%) require 840t cooking liquid. Among them, the eucalyptus chips contain 118t of water, and the 12% alkali requires 180t of recovered alkali solution (concentration 20%, providing 36t of sodium hydroxide required for cooking and 8.4t of sodium carbonate remaining), which provides 135.6t of water, and the remaining 586.4t of cooking liquid is provided by 666.36t of black liquor (solid content 12%); the three-stage heating process of the cooking process is: first heating to 145℃ and keeping warm for 1h, then heating to 155℃ and keeping warm for 1h, and finally heating to 165℃ and keeping warm for 1h. After cooking, 192.6t of semi-chemical brown pulp with special structure is obtained, and the pulp yield is 64.20%.

[0070] After five reverse washing processes for the raw pulp and triple refining, 192.6 tons of semi-chemical pulp with a special structure of 21°SR-23°SR was obtained; 385.2 tons of washing water was required for each washing process.

[0071] 2. Prepare the slurry.

[0072] Pulp preparation formula: 192.6t semi-chemical pulp with special structure is used as the key and core component (pulp preparation proportion is 25%), and then 577.49t recycled pulp (beating degree 23°SR-24°SR), 154.08kg fatty alcohol defoamer and 154.08kg polyacrylamide are added.

[0073] Pulping process: First, 192.6t of semi-chemical pulp with a special structure (25% of the pulp) and 577.49t of recycled pulp are mixed and evenly mixed by spiral stirring in the pulping tank; then, 154.08kg of fatty alcohol defoaming agent and 154.08kg of polyacrylamide are added in sequence according to the total mass of the mixed pulp, and the pulping is fully mixed again to complete the pulping.

[0074] 3. Production of high-strength corrugated paper

[0075] The prepared slurry is sent to the Fourdrinier through a power screen. During the papermaking process, 34.65t of starch solution (34.30t of starch and 0.35t of ammonium persulfate are cooked at 95°C) and 1.54t of alkyl ketene dimer are mixed into the prepared slurry. The slurry is then dried at a steam pressure of 0.3MPa-0.4MPa, a running speed of 390m / min and a drying temperature of 80°C-160°C (48 cylinders) to produce about 804.74t of high-strength corrugated paper with a width of 4.5m and a basis weight of 130g / m2.

[0076] 4. Product quality test results

[0077] The sampled products were tested and their main properties, including tensile index of 52.92N·m / g, tear length of 5.4km, ring pressure index of 8.56N·m / g and compactness of 0.57g·cm3, were better than the standard requirements of GB / T 13023-2008 Corrugated Core (Base) Paper, which stipulates that the tensile index is not less than 49.00N·m / g, the tear length is not less than 5.00km, the ring pressure index is not less than 8.5N·m / g and the compactness is not less than 0.55g·cm3. Therefore, the corrugated base paper products meet the AAA grade requirements stipulated in the standard.

[0078] Embodiment 3

[0079] Taking the daily cooking of 300t of bone-dry eucalyptus as an example, this implementation uses 12% alkali and 35% semi-chemical pulp, and the specific steps are as follows:

[0080] 1. Preparation of semi-chemical pulp with special structure.

[0081] 418t (moisture content 28.23%, absolute dryness 300t) of eucalyptus raw material was cut into wood chips of suitable thickness and size by a slicer.

[0082] Then the wood chips are cooked and pulped. The cooking method is: the mass ratio of absolute dry wood chips to cooking liquid is 1:2.8, that is, 300t absolute dry eucalyptus chips (moisture content 28.23%) require 840t cooking liquid. Among them, the eucalyptus chips contain 118t of water, and the 12% alkali requires 180t of recovered alkali solution (concentration 20%, providing 36t of sodium hydroxide required for cooking and 8.4t of sodium carbonate remaining), which provides 135.6t of water, and the remaining 586.4t of cooking liquid is provided by 666.36t of black liquor (solid content 12%); the three-stage heating process of the cooking process is: first heating to 145℃ and keeping warm for 1h, then heating to 155℃ and keeping warm for 1h, and finally heating to 165℃ and keeping warm for 1h. After cooking, 192.6t of semi-chemical brown pulp with special structure is obtained, and the pulp yield is 64.20%.

[0083] After five reverse washing processes for the raw pulp and triple refining, 192.6 tons of semi-chemical pulp with a special structure of 21°SR-23°SR was obtained; 385.2 tons of washing water was required for each washing process.

[0084] 2. Prepare the slurry.

[0085] Pulping formula: 192.6t semi-chemical pulp with special structure is used as the key and core component (pulping proportion is 35%), and then 357.48t recycled pulp (beating degree 23°SR-24°SR), 99.05kg fatty alcohol defoamer and 110.06kg polyacrylamide are added.

[0086] Pulping process: First, 192.6t of semi-chemical pulp with a special structure (35% of the pulp) and 357.48t of recycled pulp are mixed and evenly mixed by spiral stirring in the pulping tank; then, 99.05kg of fatty alcohol defoaming agent and 110.06kg of polyacrylamide are added in sequence according to the total mass of the mixed pulp, and the pulping is fully mixed again to complete the pulping.

[0087] 3. Production of high-strength corrugated paper.

[0088] The prepared slurry is sent to the Fourdrinier through a power screen. During the papermaking process, 23.1t of starch solution (made by cooking 22.64t of starch and 0.46t of ammonium persulfate at 95°C) and 1.1t of alkyl ketene dimer are mixed into the prepared slurry. The slurry is then dried at a steam pressure of 0.3MPa-0.4MPa, a running speed of 390m / min and a drying temperature of 80°C-160°C (48 cylinders) to produce about 573.18t of high-strength corrugated paper with a width of 4.5m and a basis weight of 130g / m2.

[0089] 4. Product quality test results

[0090] The sampled products were tested and their main properties, including tensile index of 54.88N·m / g, tear length of 5.6km, ring pressure index of 8.64N·m / g and compactness of 0.58g·cm3, were better than the standard requirements of GB / T13023-2008 Corrugated Core (Base) Paper, which stipulates that the tensile index is not less than 49.00N·m / g, the tear length is not less than 5.00km, the ring pressure index is not less than 8.5N·m / g and the compactness is not less than 0.55g·cm3. Therefore, the corrugated base paper products meet the AAA grade requirements stipulated in the standard.

[0091] Of course, the present application may have many other implementations. Based on the present implementation, other implementations obtained by ordinary technicians in this field without any creative work are all within the scope of protection of the present application.

Claims

1. A method for preparing high-strength corrugated paper using semi-chemical pulp, characterized in that: The following steps are involved: Step S1, preparing semi-chemical pulp, using cooking liquid to circulate and cook fiber raw materials in a vertical digester to obtain semi-chemical pulp with lignin and sugar molecules attached to the fiber surface; Step S2, preparing a pulping material of high-strength corrugated base paper with semi-chemical pulp, wherein the proportion of each component of the pulping material of high-strength corrugated base paper in terms of mass percentage is: Step S3, using a Fourdrinier paper machine to make high-strength corrugated paper, and mixing the alkyl ketene dimer into the slurry during the making process.

2. The method for preparing high-strength corrugated paper with semi-chemical pulp according to claim 1, characterized in that: The proportions of the components of the cooking liquid used in step S1 are as follows in terms of mass percentage: Black liquor 50.0%-70.0% Sodium hydroxide 1 1.5%-14.5% Sodium carbonate 2.5%-3.5%.

3. The method for preparing high-strength corrugated paper with semi-chemical pulp according to claim 2, characterized in that: The cooking temperature in the vertical cooker is 140° C.-170° C., and the cooking time is 3 to 4 hours.

4. The method for preparing high-strength corrugated paper with semi-chemical pulp according to claim 3, characterized in that: The heating process of the vertical steamer is to first heat the temperature to 140°C-145°C and keep it for 1 hour, then heat the temperature to 155°C and keep it for 1 hour, and finally heat the temperature to 165°C-170°C and keep it for 1-2 hours.

5. The method for preparing high-strength corrugated paper with semi-chemical pulp according to claim 4, characterized in that: In the step S1, the fiber pulp after the circulation cooking is completed needs to be reversely washed five times in the pulp washing tank, and the washed fiber pulp is subjected to triple pulping to obtain semi-chemical pulp, and the beating degree of the semi-chemical pulp is 21°SR-23°SR. The black liquor after the circulation cooking is completed and the pulping wastewater generated by the first reverse pulping are re-added to the vertical digester after alkali recovery treatment.

6. The method for preparing high-strength corrugated paper with semi-chemical pulp according to claim 1, characterized in that: In the step S2, the pulping of the high-strength corrugated base paper is prepared in a pulping tank, and a stirrer is provided in the pulping tank. During pulping, semi-chemical pulp and recycled pulp are first added to the pulping tank for stirring, and then 0.018%-0.02% fatty alcohol defoamer and 0.02%-0.022% polyacrylamide are added according to the total mass of the mixed pulp, and the pulping is fully mixed again to complete the pulping.

7. The method for preparing high-strength corrugated paper with semi-chemical pulp according to claim 6, characterized in that: The beating degree of the recycled pulp is 23°SR-24°SR.

8. The method for preparing high-strength corrugated paper with semi-chemical pulp according to claim 1, characterized in that: In the step S3, during the papermaking process, 42kg-45kg of starch solution and 2kg of alkyl ketene dimer are mixed into each ton of slurry.

9. The method for preparing high-strength corrugated paper with semi-chemical pulp according to claim 8, characterized in that: When the fourdrinier papermaking machine is used for papermaking, the steam pressure is 0.3MPa-0.4MPa, the operating speed is 350m / min-400m / min, the drying temperature is 80℃-160℃, the width of the high-strength corrugated paper is 4.0m-4.5m, and the basis weight is 120g / m2-140g / m2.

10. The method for preparing high-strength corrugated paper with semi-chemical pulp according to claim 8, characterized in that: The starch solution is prepared by mixing 98%-99% starch and 1%-2% ammonium persulfate, cooking at 95° C. for 60 min-70 min, and then keeping the mixture warm for 10 min to obtain the starch solution.

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