Preparation method of corrugated paper

Abstract

The present invention belongs to the technical field of the preparation of corrugated paper, and specifically relates to a method for preparing corrugated paper. The method for preparing corrugated paper according to the present invention comprises the following steps: (1) preparing a mixed slurry; (2) preparing base paper and a corrugated paper core; (3) preparing corrugated paper. The method for preparing corrugated paper according to the present invention uses larch kraft pulp, bleached acacia pulp and bleached flax pulp as basic raw materials, which are modified by polyamidoamine, styrene-butadiene emulsion and poly(methyl ethylene carbonate), and at the same time, a self-made binder is selected for adhesion. The various steps cooperate with each other to ensure that the prepared corrugated paper has excellent bursting strength, puncture strength and edge crush strength.

Description

Technical Field

[0001] The present invention belongs to the technical field of the preparation of corrugated paper, and specifically relates to a method for preparing corrugated paper. Background Art

[0002] Corrugated paper is a composite material composed of a curled or wavy fiberboard (corrugation) and flat cardboard on both sides, with a hollow core structure. With the development of the economy and the improvement of people's living standards, corrugated paper is increasingly widely used in the packaging field. Corrugated paper has many advantages such as light weight, low cost, high strength, and good cushioning performance.

[0003] The preparation process of traditional corrugated paper is relatively simple, usually using virgin wood pulp as the main raw material and made through a certain processing technology. However, the strength of this kind of corrugated paper is limited. Especially when facing heavy objects or being impacted by a large external force, it is easy to deform, break, etc., affecting its packaging performance.

[0004] In addition, the strength of the existing corrugated paper will also be greatly affected when facing a humid environment. Due to the water absorption of the paper itself, when the environmental humidity is high or it comes into contact with water, the corrugated paper is prone to softening and deformation, resulting in a significant decline in its packaging performance. Therefore, how to improve the strength of corrugated paper has become an urgent problem to be solved. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for preparing corrugated paper. The corrugated paper prepared by using this method has excellent bursting strength, puncture strength, and edge crush strength.

[0006] The method for preparing corrugated paper described in the present invention comprises the following steps:

[0007] (1) Respectively crush and beat larch sulfate pulp, bleached acacia pulp, and bleached flax pulp to obtain the slurry of larch sulfate pulp, the slurry of bleached acacia pulp, and the slurry of bleached flax pulp, and then mix the slurry of larch sulfate pulp, the slurry of bleached acacia pulp, and the slurry of bleached flax pulp to prepare a mixed slurry;

[0008] (2) Add polyamidoamine and citric acid to the mixed slurry prepared in step (1), stir and mix for 25 - 30 min, heat up to 85 - 88 °C and condense for 12 - 14 min, then add styrene - butadiene emulsion and Tween - 80 and stir for 35 - 38 min, and finally add poly(methyl ethylene carbonate) and stir and mix for 15 - 20 min to prepare the base paper pulp. Use a paper machine to prepare the base paper from the base paper pulp, and the base paper is corrugated and formed to prepare a corrugated paper core;

[0009] (3) Uniformly coat the surface of the corrugated paper core with an adhesive, and then bond two pieces of base paper to the upper and lower sides of the corrugated paper core respectively, and obtain corrugated paper through drying and baking.

[0010] Among them:

[0011] The bleached acacia pulp described in step (1) is purchased from Asia Symbol (Shandong) Pulp & Paper Co., Ltd., the larch kraft pulp is purchased from Nine Dragons Xing'an Pulp & Paper (Inner Mongolia) Co., Ltd., and the bleached flax pulp is purchased from Mudanjiang Hengfeng Paper Co., Ltd.

[0012] In step (1), the mass ratio of larch kraft pulp, bleached acacia pulp, and bleached flax pulp is 5.7:2.5:1.8.

[0013] In step (1), the beating degree of the larch kraft pulp slurry is 30°SR, and the mass concentration of the larch kraft pulp slurry is 4.4%; the beating degree of the bleached acacia pulp slurry is 35°SR, and the mass concentration of the bleached acacia pulp slurry is 5.2%; the beating degree of the bleached flax pulp slurry is 25°SR, and the mass concentration of the bleached flax pulp slurry is 3.5%.

[0014] In step (2), the mass of polyamidoamine accounts for 1.2 - 1.3% of the total mass of larch kraft pulp, bleached acacia pulp, and bleached flax pulp; the mass of styrene-butadiene emulsion accounts for 2.5 - 2.7% of the total mass of larch kraft pulp, bleached acacia pulp, and bleached flax pulp; the mass of poly(methyl ethylene carbonate) accounts for 0.8 - 1.0% of the total mass of larch kraft pulp, bleached acacia pulp, and bleached flax pulp; the mass of Tween-80 accounts for 0.2% of the total mass of larch kraft pulp, bleached acacia pulp, and bleached flax pulp; citric acid is added to adjust the pH value of the system to 5.5.

[0015] In step (2), the temperature of corrugating and forming is 175 - 178 °C.

[0016] In step (3), the drying temperature is 40 - 45 °C, the drying time is 1 - 1.2 h, the baking temperature is 105 - 108 °C, and the baking time is 38 - 40 min.

[0017] The preparation method of the adhesive described in step (3) consists of the following steps: Mix modified corn starch, phosphate starch, and water, stir and dissolve at 78 - 80 °C for 35 - 38 min, then add epichlorohydrin and continue to stir for 23 - 25 min, and cool to 30 - 33 °C after vacuum pumping to obtain the adhesive.

[0018] Among them:

[0019] The mass ratio of modified corn starch to phosphate starch is 6 - 7:1.

[0020] The mass of water is 2.8 times the sum of the masses of modified corn starch and phosphate starch.

[0021] The mass of epichlorohydrin accounts for 2.4 - 2.6% of the mass of modified corn starch.

[0022] The preparation method of the modified corn starch comprises the following steps:

[0023] ① Mix corn starch and hydrochloric acid, stir and dissolve at 55 °C for 2.2 h, then add sodium hydroxide to adjust the system to a neutral environment, raise the temperature to 70 °C and continue stirring for 40 min to gelatinize it;

[0024] ② Cool the reaction system to 55 °C, add dodecyldimethylbetaine, styrene - acrylic acid copolymer and ammonium persulfate, then add hydrochloric acid to adjust the pH value of the reaction system to 4.5, and finally raise the temperature to 75 °C and continue reacting for 1.6 h. After the reaction is completed, add resorcinol to terminate the reaction;

[0025] ③ Add sodium bicarbonate to adjust the pH value of the reaction system to 6.0, and prepare the modified corn starch through post - treatment.

[0026] Among them:

[0027] In step ①, the mass - to - volume ratio of corn starch to hydrochloric acid is 1:2.4, with the unit of g / mL.

[0028] In step ②, the mass of dodecyldimethylbetaine accounts for 2.5% of the mass of corn starch, the mass of styrene - acrylic acid copolymer accounts for 22% of the mass of corn starch, the mass of ammonium persulfate accounts for 0.4% of the mass of corn starch, and the mass of resorcinol accounts for 3.5% of the mass of corn starch.

[0029] In step ③, the post - treatment is ethanol precipitation, washing with distilled water, centrifugation, and then drying at 55 °C for 8 h.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] (1) In the preparation method of the corrugated paper of the present invention, larch kraft pulp, bleached acacia pulp and bleached flax pulp are used as the main papermaking raw materials, and the three are used in combination. Fundamentally, it ensures the strength of the prepared corrugated paper. Among them, larch kraft pulp itself has good moisture - resistance, strength and good tear - resistance, playing a role of skeleton support, but its flexibility is poor; while bleached acacia pulp can fill the fiber gaps, improve the evenness and increase the inter - layer bonding strength; in addition, bleached flax pulp is added, which can enhance the flexibility of the corrugated paper, reduce the delamination and brittleness of the corrugated paper, and improve the durability of the corrugated paper.

[0032] (2) In the method for preparing corrugated paper according to the present invention, polyamidoamine forms a cross-linked network through chemical interaction with the hydroxyl functional groups on the fiber surface, enhancing the dry strength and wet strength of the paper. Citric acid acts as a catalyst to accelerate the condensation reaction. The added styrene-butadiene emulsion forms a film on the fiber surface, enhancing the bonding force between fibers and improving the tensile strength and folding endurance of the paper. The carbonate groups of poly(ethylene carbonate) have a weak interaction with cellulose hydroxyl groups, and its addition can improve the waterproof performance of the corrugated paper. Thus, the synergistic effect of these three ensures the strength of the prepared corrugated paper.

[0033] (3) In the method for preparing corrugated paper according to the present invention, modified corn starch and phosphate starch are used in combination as the binder, and epichlorohydrin is used as the cross-linking agent. Modified corn starch has good bonding properties and water resistance, while phosphate starch has better film-forming properties. Epichlorohydrin undergoes a cross-linking reaction with starch molecules to form epoxy starch with a three-dimensional network structure, thereby improving the strength and water resistance of the binder. Among them, the modified corn starch is first acid-modified to gelatinize it, and then ammonium persulfate is used as an initiator to initiate a free radical polymerization reaction between styrene-acrylic copolymer and starch molecules to form modified corn starch with a graft structure. Dodecyl dimethyl betaine can accelerate the penetration of the starch adhesive into the paper product and improve the bonding speed. Thus, the prepared binder has good bonding properties and water resistance.

[0034] (4) In the method for preparing corrugated paper according to the present invention, larch kraft pulp, bleached acacia pulp and bleached flax pulp are used as the basic raw materials, modified by polyamidoamine, styrene-butadiene emulsion and poly(ethylene carbonate), and a self-made binder is selected for adhesion. The synergistic effect between each step ensures that the prepared corrugated paper has excellent bursting strength, puncture strength and edge crush strength. Detailed implementation mode

[0035] The present invention will be further described below in conjunction with embodiments.

[0036] Example 1

[0037] The method for preparing corrugated paper described in this Example 1 consists of the following steps:

[0038] (1) The larch kraft pulp, bleached acacia pulp and bleached flax pulp are respectively subjected to crushing and beating treatments to obtain the larch kraft pulp slurry, bleached acacia pulp slurry and bleached flax pulp slurry, and then the larch kraft pulp slurry, bleached acacia pulp slurry and bleached flax pulp slurry are mixed to prepare a mixed slurry;

[0039] (2) Add polyamidoamine and citric acid to the mixed slurry prepared in step (1), stir and mix for 27 min, heat up to 86 °C and condense for 13 min, then add styrene-butadiene emulsion and Tween-80 and stir for 36 min, and finally add poly(ethylene carbonate) and stir and mix for 17 min to prepare the base paper pulp. Use a paper machine to prepare the base paper from the base paper pulp, and prepare the corrugated paper core by corrugating and forming the base paper.

[0040] (3) Uniformly coat the surface of the corrugated paper core with an adhesive, and then bond two pieces of base paper to the upper and lower sides of the corrugated paper core respectively, and obtain the corrugated paper through drying and baking.

[0041] Among them:

[0042] The bleached acacia pulp described in step (1) is purchased from APP (Shandong) Pulp & Paper Co., Ltd., the larch kraft pulp is purchased from Nine Dragons Xing'an Pulp & Paper (Inner Mongolia) Co., Ltd., and the bleached flax pulp is purchased from Mudanjiang Hengfeng Paper Co., Ltd.

[0043] In step (1), the mass ratio of larch kraft pulp, bleached acacia pulp, and bleached flax pulp is 5.7:2.5:1.8.

[0044] In step (1), the beating degree of the larch kraft pulp slurry is 30 °SR, and the mass concentration of the larch kraft pulp slurry is 4.4%; the beating degree of the bleached acacia pulp slurry is 35 °SR, and the mass concentration of the bleached acacia pulp slurry is 5.2%; the beating degree of the bleached flax pulp slurry is 25 °SR, and the mass concentration of the bleached flax pulp slurry is 3.5%.

[0045] In step (2), the mass of polyamidoamine accounts for 1.25% of the total mass of larch kraft pulp, bleached acacia pulp, and bleached flax pulp; the mass of styrene-butadiene emulsion accounts for 2.6% of the total mass of larch kraft pulp, bleached acacia pulp, and bleached flax pulp; the mass of poly(ethylene carbonate) accounts for 0.9% of the total mass of larch kraft pulp, bleached acacia pulp, and bleached flax pulp; the mass of Tween-80 accounts for 0.2% of the total mass of larch kraft pulp, bleached acacia pulp, and bleached flax pulp; add citric acid to adjust the pH value of the system to 5.5.

[0046] In step (2), the temperature of corrugating and forming is 176 °C.

[0047] In step (3), the drying temperature is 43 °C, the drying time is 1.1 h, the baking temperature is 106 °C, and the baking time is 39 min.

[0048] The preparation method of the binder described in step (3) consists of the following steps: Mix modified corn starch, phosphate starch, and water, stir and dissolve at 79 °C for 36 min, then add epichlorohydrin and continue stirring for 24 min. After vacuum pumping, cool to 31 °C to obtain the binder.

[0049] Among them:

[0050] The mass ratio of modified corn starch to phosphate starch is 6.5:1.

[0051] The mass of water is 2.8 times the sum of the masses of modified corn starch and phosphate starch.

[0052] The mass of epichlorohydrin accounts for 2.5% of the mass of modified corn starch.

[0053] The preparation method of the modified corn starch consists of the following steps:

[0054] ① Mix corn starch and hydrochloric acid, stir and dissolve at 55 °C for 2.2 h, then add sodium hydroxide to adjust the system to a neutral environment, and raise the temperature to 70 °C and continue stirring for 40 min to gelatinize it;

[0055] ② Cool the reaction system to 55 °C, add dodecyldimethylbetaine, styrene-acrylic copolymer, and ammonium persulfate, then add hydrochloric acid to adjust the pH value of the reaction system to 4.5, and finally raise the temperature to 75 °C and continue reacting for 1.6 h. After the reaction is completed, add resorcinol to terminate the reaction;

[0056] ③ Add sodium bicarbonate to adjust the pH value of the reaction system to 6.0, and obtain the modified corn starch through post-treatment.

[0057] Among them:

[0058] In step ①, the mass-volume ratio of corn starch to hydrochloric acid is 1:2.4, with the unit of g / mL.

[0059] In step ②, the mass of dodecyldimethylbetaine accounts for 2.5% of the mass of corn starch, the mass of styrene-acrylic copolymer accounts for 22% of the mass of corn starch, the mass of ammonium persulfate accounts for 0.4% of the mass of corn starch, and the mass of resorcinol accounts for 3.5% of the mass of corn starch.

[0060] The post-treatment in step ③ is ethanol precipitation, washing with distilled water, centrifugation, and then drying at 55 °C for 8 h.

[0061] Example 2

[0062] The preparation method of the corrugated paper described in this Example 2 consists of the following steps:

[0063] (1) The larch sulfate pulp, bleached acacia pulp, and bleached flax pulp are respectively broken and beaten to obtain the slurry of larch sulfate pulp, the slurry of bleached acacia pulp, and the slurry of bleached flax pulp. Then, the slurry of larch sulfate pulp, the slurry of bleached acacia pulp, and the slurry of bleached flax pulp are mixed to prepare a mixed slurry.

[0064] (2) Polyamidoamine and citric acid are added to the mixed slurry prepared in step (1), and stirred and mixed for 30 min. Then, the temperature is raised to 88 °C and condensed for 14 min. Subsequently, styrene-butadiene emulsion and Tween-80 are added and stirred for 38 min. Finally, poly(methyl ethylene carbonate) is added and stirred and mixed for 15 min to prepare the base paper pulp. The base paper pulp is made into base paper by a paper machine, and the base paper is corrugated and formed to prepare a corrugated paper core.

[0065] (3) The surface of the corrugated paper core is evenly coated with an adhesive, and then two pieces of base paper are respectively bonded to the upper and lower sides of the corrugated paper core, and dried and baked to prepare a corrugated paper.

[0066] Among them:

[0067] The bleached acacia pulp described in step (1) is purchased from APP (Shandong) Pulp & Paper Co., Ltd., the larch sulfate pulp is purchased from Nine Dragons Xing'an Pulp & Paper (Inner Mongolia) Co., Ltd., and the bleached flax pulp is purchased from Mudanjiang Hengfeng Paper Co., Ltd.

[0068] In step (1), the mass ratio of larch sulfate pulp, bleached acacia pulp, and bleached flax pulp is 5.7:2.5:1.8.

[0069] In step (1), the beating degree of the larch sulfate pulp slurry is 30 °SR, and the mass concentration of the larch sulfate pulp slurry is 4.4%; the beating degree of the bleached acacia pulp slurry is 35 °SR, and the mass concentration of the bleached acacia pulp slurry is 5.2%; the beating degree of the bleached flax pulp slurry is 25 °SR, and the mass concentration of the bleached flax pulp slurry is 3.5%.

[0070] In step (2), the mass of polyamidoamine accounts for 1.3% of the total mass of larch sulfate pulp, bleached acacia pulp, and bleached flax pulp; the mass of styrene-butadiene emulsion accounts for 2.7% of the total mass of larch sulfate pulp, bleached acacia pulp, and bleached flax pulp; the mass of poly(methyl ethylene carbonate) accounts for 0.8% of the total mass of larch sulfate pulp, bleached acacia pulp, and bleached flax pulp; the mass of Tween-80 accounts for 0.2% of the total mass of larch sulfate pulp, bleached acacia pulp, and bleached flax pulp; citric acid is added to adjust the pH value of the system to 5.5.

[0071] In step (2), the temperature of corrugating and forming is 178 °C.

[0072] In step (3), the drying temperature is 45°C, the drying time is 1.2 h, the baking temperature is 108°C, and the baking time is 38 min.

[0073] The preparation method of the binder in step (3) consists of the following steps: Mix modified corn starch, phosphate starch, and water, stir and dissolve at 78°C for 35 min, then add epichlorohydrin and continue stirring for 25 min, and cool to 33°C after vacuum pumping to obtain the binder.

[0074] Among them:

[0075] The mass ratio of modified corn starch to phosphate starch is 7:1.

[0076] The mass of water is 2.8 times the sum of the masses of modified corn starch and phosphate starch.

[0077] The mass of epichlorohydrin accounts for 2.6% of the mass of modified corn starch.

[0078] The preparation method of the modified corn starch consists of the following steps:

[0079] ① Mix corn starch and hydrochloric acid, stir and dissolve at 55°C for 2.2 h, then add sodium hydroxide to adjust the system to a neutral environment, and raise the temperature to 70°C and continue stirring for 40 min to gelatinize it;

[0080] ② Cool the reaction system to 55°C, add dodecyldimethylbetaine, styrene-acrylic acid copolymer, and ammonium persulfate, then add hydrochloric acid to adjust the pH value of the reaction system to 4.5, and finally raise the temperature to 75°C and continue reacting for 1.6 h. After the reaction is completed, add resorcinol to terminate the reaction;

[0081] ③ Add sodium bicarbonate to adjust the pH value of the reaction system to 6.0, and obtain the modified corn starch through post-treatment.

[0082] Among them:

[0083] In step ①, the mass-volume ratio of corn starch to hydrochloric acid is 1:2.4, with the unit of g / mL.

[0084] In step ②, the mass of dodecyldimethylbetaine accounts for 2.5% of the mass of corn starch, the mass of styrene-acrylic acid copolymer accounts for 22% of the mass of corn starch, the mass of ammonium persulfate accounts for 0.4% of the mass of corn starch, and the mass of resorcinol accounts for 3.5% of the mass of corn starch.

[0085] The post-treatment in step ③ is precipitation with ethanol, washing with distilled water, centrifugation, and then drying at 55°C for 8 h.

[0086] Example 3

[0087] The preparation method of the corrugated paper described in this Embodiment 3 consists of the following steps:

[0088] (1) Respectively crush and beat the larch sulfate pulp, bleached acacia pulp and bleached flax pulp to obtain the larch sulfate pulp slurry, bleached acacia pulp slurry and bleached flax pulp slurry, and then mix the larch sulfate pulp slurry, bleached acacia pulp slurry and bleached flax pulp slurry to prepare a mixed slurry;

[0089] (2) Add polyamidoamine and citric acid to the mixed slurry prepared in step (1), stir and mix for 25 min, heat up to 85 °C and condense for 12 min, then add styrene-butadiene emulsion and Tween-80 and stir for 35 min, and finally add poly(methyl ethylene carbonate) and stir and mix for 20 min to prepare the base paper pulp. Use a paper machine to prepare the base paper from the base paper pulp, and prepare the corrugated paper core by corrugating and forming the base paper;

[0090] (3) Uniformly coat the surface of the corrugated paper core with an adhesive, and then bond two pieces of base paper on the upper and lower sides of the corrugated paper core respectively, and prepare the corrugated paper through drying and baking.

[0091] Among them:

[0092] In step (1), the bleached acacia pulp is purchased from Asia Symbol (Shandong) Pulp & Paper Co., Ltd., the larch sulfate pulp is purchased from Nine Dragons Xing'an Pulp & Paper (Inner Mongolia) Co., Ltd., and the bleached flax pulp is purchased from Mudanjiang Hengfeng Paper Co., Ltd.

[0093] In step (1), the mass ratio of the larch sulfate pulp, bleached acacia pulp and bleached flax pulp is 5.7:2.5:1.8.

[0094] In step (1), the beating degree of the larch sulfate pulp slurry is 30 °SR, and the mass concentration of the larch sulfate pulp slurry is 4.4%; the beating degree of the bleached acacia pulp slurry is 35 °SR, and the mass concentration of the bleached acacia pulp slurry is 5.2%; the beating degree of the bleached flax pulp slurry is 25 °SR, and the mass concentration of the bleached flax pulp slurry is 3.5%.

[0095] In step (2), the mass of polyamidoamine accounts for 1.2% of the total mass of the larch sulfate pulp, bleached acacia pulp and bleached flax pulp; the mass of styrene-butadiene emulsion accounts for 2.5% of the total mass of the larch sulfate pulp, bleached acacia pulp and bleached flax pulp; the mass of poly(methyl ethylene carbonate) accounts for 1.0% of the total mass of the larch sulfate pulp, bleached acacia pulp and bleached flax pulp; the mass of Tween-80 accounts for 0.2% of the total mass of the larch sulfate pulp, bleached acacia pulp and bleached flax pulp; add citric acid to adjust the pH value of the system to 5.5.

[0096] In step (2), the temperature for corrugating forming is 175 °C.

[0097] In step (3), the drying temperature is 40 °C, the drying time is 1 h, the baking temperature is 105 °C, and the baking time is 38 min.

[0098] The preparation method of the binder in step (3) consists of the following steps: Mix modified corn starch, phosphate starch, and water, stir and dissolve at 78 °C for 35 min, then add epichlorohydrin and continue stirring for 23 min, cool to 30 °C after vacuum pumping to obtain the binder.

[0099] Among them:

[0100] The mass ratio of modified corn starch to phosphate starch is 6:1.

[0101] The mass of water is 2.8 times the sum of the masses of modified corn starch and phosphate starch.

[0102] The mass of epichlorohydrin accounts for 2.4% of the mass of modified corn starch.

[0103] The preparation method of the modified corn starch consists of the following steps:

[0104] ① Mix corn starch and hydrochloric acid, stir and dissolve at 55 °C for 2.2 h, then add sodium hydroxide to adjust the system to a neutral environment, and raise the temperature to 70 °C and continue stirring for 40 min to gelatinize it;

[0105] ② Cool the reaction system to 55 °C, add dodecyldimethylbetaine, styrene-acrylic copolymer, and ammonium persulfate, then add hydrochloric acid to adjust the pH value of the reaction system to 4.5, and finally raise the temperature to 75 °C and continue reacting for 1.6 h. After the reaction is completed, add resorcinol to terminate the reaction;

[0106] ③ Add sodium bicarbonate to adjust the pH value of the reaction system to 6.0, and obtain the modified corn starch through post-treatment.

[0107] Among them:

[0108] In step ①, the mass-volume ratio of corn starch to hydrochloric acid is 1:2.4, with the unit of g / mL.

[0109] In step ②, the mass of dodecyldimethylbetaine accounts for 2.5% of the mass of corn starch, the mass of styrene-acrylic copolymer accounts for 22% of the mass of corn starch, the mass of ammonium persulfate accounts for 0.4% of the mass of corn starch, and the mass of resorcinol accounts for 3.5% of the mass of corn starch.

[0110] The post-treatment in step ③ is ethanol precipitation, distilled water washing, centrifugation, and then drying at 55 °C for 8 h.

[0111] Comparative Example 1

[0112] The preparation method of the corrugated paper described in this Comparative Example 1 is the same as that of Example 1. The only difference is that in step (2), styrene-butadiene emulsion, Tween-80 and poly(methyl ethylene carbonate) are no longer added, and only the condensation reaction is carried out.

[0113] Comparative Example 2

[0114] The preparation method of the corrugated paper described in this Comparative Example 2 is the same as that of Example 1. The only difference is that in step (3), when preparing the binder, instead of using modified corn starch, corn starch is directly used.

[0115] The performance of the corrugated papers prepared in Examples 1-3 and Comparative Examples 1-2 was tested. Among them, the water absorption was tested according to GB / T 1540-2002 "Determination of water absorption of paper and paperboard", the bursting strength was tested according to GB / T 6545-1998 "Determination method for bursting strength of corrugated board", the puncture strength was tested according to GB / T 2679.7-2005 "Determination of puncture strength of paperboard", and the edge crush strength was tested according to GB / T 6546-1998 "Determination method for edge crush strength of corrugated board". The test results are shown in Table 1 below:

[0116] Table 1 Test results of corrugated paper performance

[0117]

Claims

1. A method for preparing corrugated paper, characterized in that: It consists of the following steps: (1) crushing and beating larch kraft pulp, bleached acacia pulp and bleached flax pulp respectively to obtain larch kraft pulp slurry, bleached acacia pulp slurry and bleached flax pulp slurry, and then mixing the larch kraft pulp slurry, bleached acacia pulp slurry and bleached flax pulp slurry to prepare a mixed slurry; (2) adding polyamide amine and citric acid to the mixed slurry prepared in step (1) and stirring for 25-30 minutes, heating to 85-88° C. for condensation for 12-14 minutes, then adding styrene-butadiene emulsion and Tween-80 and stirring for 35-38 minutes, and finally adding polymethyl ethylene carbonate and stirring for 15-20 minutes to prepare base paper pulp, using a papermaking machine to prepare base paper from the base paper pulp, and preparing a corrugated paper core by corrugating the base paper; (3) The surface of the corrugated paper core is evenly coated with an adhesive, and then two pieces of base paper are respectively bonded to the upper and lower sides of the corrugated paper core, and then dried and baked to obtain corrugated paper; in: The method for preparing the binder in step (3) comprises the following steps: mixing modified corn starch, phosphate starch and water, stirring and dissolving at 78-80° C. for 35-38 minutes, then adding epichlorohydrin and continuing stirring for 23-25 ​​minutes, and cooling to 30-33° C. after vacuuming to prepare the binder; The preparation method of the modified corn starch consists of the following steps: ① Mix corn starch and hydrochloric acid and stir to dissolve at 55℃ for 2.2h, then add sodium hydroxide to adjust the system to a neutral environment, raise the temperature to 70℃ and continue stirring for 40min to gelatinize; ② Cool the reaction system to 55°C, add dodecyl dimethyl betaine, styrene-acrylic acid copolymer and ammonium persulfate, then add hydrochloric acid to adjust the pH value of the reaction system to 4.5, and finally raise the temperature to 75°C to continue the reaction for 1.6 hours. After the reaction is completed, add resorcinol to terminate the reaction; ③ Sodium bicarbonate was added to adjust the pH value of the reaction system to 6.0, and modified corn starch was prepared through post-treatment.

2. The method for preparing corrugated paper according to claim 1, characterized in that: In step (1), the mass ratio of larch kraft pulp, bleached acacia pulp and bleached flax pulp is 5.7:2.5:1.8; In step (1), the beating degree of larch kraft pulp slurry is 30°SR, and the mass concentration of larch kraft pulp slurry is 4.4%; the beating degree of bleached acacia pulp slurry is 35°SR, and the mass concentration of bleached acacia pulp slurry is 5.2%; the beating degree of bleached flax pulp slurry is 25°SR, and the mass concentration of bleached flax pulp slurry is 3.5%.

3. The method for preparing corrugated paper according to claim 1, characterized in that: In step (2), the mass of the polyamide amine accounts for 1.2-1.3% of the total mass of larch kraft pulp, bleached acacia pulp and bleached flax pulp; the mass of the styrene-butadiene emulsion accounts for 2.5-2.7% of the total mass of larch kraft pulp, bleached acacia pulp and bleached flax pulp; the mass of the polymethyl ethylene carbonate accounts for 0.8-1.0% of the total mass of larch kraft pulp, bleached acacia pulp and bleached flax pulp; the mass of Tween-80 accounts for 0.2% of the total mass of larch kraft pulp, bleached acacia pulp and bleached flax pulp; and citric acid is added to adjust the pH value of the system to 5.

5.

4. The method for preparing corrugated paper according to claim 1, characterized in that: The temperature of corrugating in step (2) is 175-178°C.

5. The method for preparing corrugated paper according to claim 1, characterized in that: In step (3), the drying temperature is 40-45°C, the drying time is 1-1.2h, the drying temperature is 105-108°C, and the drying time is 38-40min.

6. The method for preparing corrugated paper according to claim 1, characterized in that: In the preparation method of the binder, the mass ratio of modified corn starch to phosphate starch is 6-7:1; In the preparation method of the binder, the mass of water is 2.8 times the mass of the modified corn starch and the phosphate starch; In the preparation method of the binder, the mass of epichlorohydrin accounts for 2.4-2.6% of the mass of the modified corn starch.

7. The method for preparing corrugated paper according to claim 1, characterized in that: In step ① of the preparation method of the modified corn starch, the mass volume ratio of corn starch to hydrochloric acid is 1:2.4, in units of g / mL; In step ② of the preparation method of the modified corn starch, the mass of dodecyl dimethyl betaine accounts for 2.5% of the mass of corn starch, the mass of styrene-acrylic acid copolymer accounts for 22% of the mass of corn starch, the mass of ammonium persulfate accounts for 0.4% of the mass of corn starch, and the mass of resorcinol accounts for 3.5% of the mass of corn starch.

8. The method for preparing corrugated paper according to claim 1, characterized in that: The post-treatment in step ③ of the preparation method of the modified corn starch is ethanol precipitation, distilled water washing, centrifugation, and then drying at 55° C. for 8 hours.

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