High-strength water-resistant corrugated paper and its application in waterproof cartons

Abstract

This invention belongs to the field of corrugated paper technology, specifically relating to a high-strength, water-resistant corrugated paper and its application in waterproof cartons. This invention involves comprehensively treating the corrugated core paper using an impregnation solution and a coating. The impregnation solution utilizes modified silica sol and boron quantum dots to modify titanium dioxide, while the coating is modified to remove hydroxyethyl cellulose. This process yields a high-strength, water-resistant corrugated paper that significantly increases edge crush strength, improves the oxygen index, and effectively reduces water absorption.

Description

Technical Field

[0001] This invention belongs to the field of corrugated paper technology, specifically relating to a high-strength, water-resistant corrugated paper and its application in waterproof cartons. Background Technology

[0002] Corrugated paper is a commonly used packaging material, consisting of one or more corrugated inner cores and one or two flat outer layers. Its low basis weight, low cost, high strength, excellent cushioning properties, and environmental friendliness make it a widely used paper packaging material. Since its inception, extensive research has been conducted on the various properties of corrugated paper, including the influence of factors such as corrugated paper materials, structure, manufacturing processes, external loads, and climatic environments on its static and dynamic properties. This research has provided a clear understanding of most of the properties of corrugated paper, laying a solid foundation for its application in packaging and other fields.

[0003] Chinese patent (publication number CN117661366A) discloses a preparation process for high-strength, water-resistant composite corrugated paper. This invention utilizes terminal-amino hyperbranched fluorinated polyamide-ester as a curing agent, containing hydrophobic benzene rings and trifluoromethyl groups. This enhances the hydrophobicity of the epoxy resin sizing agent, reduces water absorption, and thus forms a hydrophobic coating on the corrugated paper surface, improving its water resistance and waterproof performance. The terminal-amino hyperbranched fluorinated polyamide-ester possesses a hyperbranched molecular chain structure, forming a three-dimensional cross-linked network in the epoxy resin, effectively reinforcing and toughening the epoxy resin, improving its impact and flexural strength, and consequently increasing the ring crush index and ring crush strength of the corrugated paper. However, this patent does not address the problems of low edge crush strength, poor flame retardancy, and high water absorption in existing corrugated paper technologies, severely impacting its practical use.

[0004] Therefore, there is an urgent need for a high-strength, water-resistant corrugated paper. This paper is produced by comprehensively treating the corrugated core paper with impregnation liquid and coating, and by modifying the key components of the impregnation liquid and coating to increase the edge crush strength of the corrugated paper, improve the oxygen index, and effectively reduce water absorption. Summary of the Invention

[0005] The purpose of this invention is to provide a high-strength, water-resistant corrugated paper and its application in waterproof cartons. The corrugated core paper is comprehensively treated by using an impregnation solution and a coating. Modified silica sol and boron quantum dots are used to modify titanium dioxide in the impregnation solution, while hydroxyethyl cellulose in the coating is modified. This process produces a high-strength, water-resistant corrugated paper that significantly increases edge crush strength, improves oxygen index, and effectively reduces water absorption.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] The first aspect of the present invention provides a high-strength water-resistant corrugated paper, the high-strength water-resistant corrugated paper comprising a corrugated core paper and a functional coating coated on the surface of the corrugated core paper, wherein the corrugated core paper is subjected to impregnation modification treatment with an impregnation solution;

[0008] The corrugated paper is made by the following steps:

[0009] Step S1: By weight, mix 10-20 parts of tetraethyl orthosilicate, 6-10 parts of paraffin, 20-24 parts of anhydrous ethanol and 20-24 parts of deionized water evenly, stir at 46-48℃ for 20-30 min, adjust the pH to 4.2-4.8 with hydrochloric acid and stir for 2-4 h, then add 20-30 parts of magnesium chloride solution with a molar concentration of 0.1-0.3 mol / L, stir at 54-60℃ for 4-6 h, then add ammonia water dropwise to adjust the pH to 7.4-7.8 and stir for 1-2 h to obtain modified silica sol;

[0010] Step S2: By weight, add 4-6 parts of sodium hydroxide to 90-100 parts of the modified silica sol, stir at 70-80°C for 50-60 minutes, then add 4-6 parts of methylcellulose and 1-3 parts of titanium dioxide and continue stirring for 30-40 minutes to obtain the impregnation solution.

[0011] Step S3: Immerse the corrugated core paper in the impregnation solution at 50-60℃ for 10-20 seconds, and then dry it in a constant temperature drying oven at 56-60℃ for 50-60 minutes to obtain the impregnated corrugated core paper.

[0012] Step S4: Apply a coating to the impregnated corrugated core paper. After coating, let it stand at room temperature for 10-20 minutes, then cure it at 100-104°C for 70-80 minutes. Finally, process it with a corrugated roller to obtain high-strength water-resistant corrugated paper.

[0013] The paraffin in the modified silica sol can form a protective film on the surface. When it comes into contact with a flame, the paraffin melts and covers the paper, acting as a physical barrier and thus slowing down the combustion process. At the same time, magnesium hydroxide grows in situ on the silica surface. At high temperatures, magnesium hydroxide can decompose into water vapor and magnesium oxide and absorb a large amount of heat, while releasing non-flammable water vapor, diluting the concentration of flammable gases, reducing the flame temperature, and increasing the oxygen index of the corrugated paper.

[0014] As a preferred embodiment, the methylcellulose is carboxymethyl cellulose and hydroxypropyl methyl cellulose; the mass ratio of the carboxymethyl cellulose and hydroxypropyl methyl cellulose is (1-2):1.

[0015] By controlling the mass ratio of carboxymethyl cellulose and hydroxypropyl methyl cellulose to ensure appropriate dosage, the edge crush strength of corrugated paper is increased, the oxygen index is improved, and water absorption is effectively reduced due to the good compounding effect.

[0016] As a preferred embodiment, the titanium dioxide is boron quantum dot modified titanium dioxide; the preparation method of the boron quantum dot modified titanium dioxide includes: mixing and stirring 60-80 parts by weight of anhydrous ethanol, 20-40 parts by weight of deionized water, 2-4 parts by weight of boron quantum dots and 8-10 parts by weight of hydrochloric acid solution with a mass concentration of 20-30% for 10-20 minutes to obtain solution A; adding 60-80 parts by weight of tetrabutyl titanate to 90-100 parts by weight of anhydrous ethanol and stirring for 20-30 minutes, then using a hydrochloric acid solution with a mass concentration of 20-30%... The pH was adjusted to 3.2–3.6 with 30% hydrochloric acid solution, and stirred for 15–30 min to obtain solution B. 80–100 parts of solution A were added to 100–120 parts of solution B and stirred for 40–60 min. Then 20–40 parts of deionized water were added and stirred for 2–4 h to form a gel. The gel was allowed to stand at room temperature for 10–12 h, and then dried at 70–80 °C for 20–22 h. The gel was then transferred to a tube furnace and calcined at 480–500 °C for 2–4 h. After cooling to room temperature, boron quantum dot modified titanium dioxide was obtained.

[0017] As a preferred embodiment, the method for preparing the boron quantum dots includes: adding 2-4 parts by weight of ammonium pentaborate and 1-2 parts by weight of boric acid to 20-25 parts by weight of deionized water and stirring for 1-2 hours; conducting a hydrothermal reaction under an argon atmosphere; cooling to room temperature after the reaction is completed; adding 1-2 parts by weight of hydrazine hydrate and stirring for 1-2 hours; centrifuging to obtain the supernatant; and freeze-drying to obtain the boron quantum dots.

[0018] As a preferred embodiment, the hydrothermal reaction is carried out at a temperature of 180–190°C for 10–12 hours.

[0019] Boron quantum dots in boron quantum dot modified titanium dioxide can form strong physical adsorption with corrugated paper fibers, improving the bonding force between fibers and thus enhancing the stability of the overall structure. Titanium dioxide has high hardness and good weather resistance, and can fill the gaps between paper fibers, providing additional structural support and improving the edge crush strength of corrugated paper.

[0020] As a preferred embodiment, the preparation method of the coating includes: mixing 4-6 parts by weight of acetic acid and 60-70 parts by weight of deionized water evenly, then adding 90-100 parts by weight of polyurethane, 1-3 parts by weight of methanol and 4-8 parts by weight of hydroxyethyl cellulose and stirring for 4-6 hours to obtain the coating.

[0021] As a preferred embodiment, the hydroxyethyl cellulose is modified hydroxyethyl cellulose; the preparation method of the modified hydroxyethyl cellulose includes: adding 20-24 parts by weight of hydroxyethyl cellulose to 100-110 parts by weight of deionized water, stirring under a nitrogen atmosphere for 1-3 hours, adding 6-8 parts by weight of cerium ammonium nitrate and 10-14 parts by weight of [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide at 36-40°C, adjusting the pH to 7.2-7.4, reacting for 4-6 hours, and precipitating with acetone after the reaction is complete. Separate to obtain a precipitate; add 36-40 parts of 2-acrylamido-2-methylpropanesulfonic acid and 10-14 parts of sodium chloride to 200-220 parts of deionized water and stir for 30-40 min, then add 40-45 parts of dimethyl diallyl ammonium chloride and 20-30 parts of the aforementioned precipitate, stir for 1-3 h to obtain a mixture, transfer the mixture to a reaction vessel, under nitrogen atmosphere protection, add 2-4 parts of potassium persulfate and react for 6-8 h at 80-84 °C, after the reaction is completed, cool to room temperature, dry, pulverize, and obtain modified hydroxyethyl cellulose.

[0022] As a preferred embodiment, the viscosity of the hydroxyethyl cellulose is 800–1200 mPa·s.

[0023] Modified hydroxyethyl cellulose contains zwitterionic polymers, which can reduce the capillary effect inside the corrugated paper and inhibit moisture absorption by changing the microstructure of the corrugated paper surface. At the same time, the modified hydroxyethyl cellulose, together with polyurethane, can form a hydrophobic barrier on the surface of the corrugated paper, effectively reducing the paper's water absorption.

[0024] As a preferred embodiment, the coating amount in the coating process is 40–50 g / m². 2 .

[0025] The second aspect of the present invention provides an application of high-strength, water-resistant corrugated paper as described in the first aspect in waterproof cartons.

[0026] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows:

[0027] 1. In this invention, modified silica sol and boron quantum dot modified titanium dioxide are first introduced through an impregnation solution, and then modified hydroxyethyl cellulose is introduced through a coating. The zwitterionic polymer of modified hydroxyethyl cellulose can adsorb with modified silica sol and boron quantum dot modified titanium dioxide to form a dense network structure, thereby improving the edge crush strength of corrugated paper and reducing its water absorption.

[0028] 2. The magnesium hydroxide in the modified silica sol of this invention can absorb a large amount of heat and release non-flammable water vapor at high temperatures. The silicon element can promote the formation of a dense carbon layer on the material surface to improve fire resistance. The boron element in the boron quantum dot modified titanium dioxide will form a stable glassy film covering the material surface at high temperatures, effectively isolating oxygen and heat. The nitrogen element in the modified hydroxyethyl cellulose can react with the free radicals generated during combustion, thereby blocking the chain reaction and slowing down the combustion process. Through the synergistic effect of magnesium-silicon-boron-nitrogen, the oxygen index of corrugated paper is significantly improved.

[0029] 3. The paraffin in the modified silica sol of this invention can form a protective film on the surface. When it encounters a flame, the paraffin melts and covers the paper, playing a physical isolation role and thus delaying the combustion process. At the same time, magnesium hydroxide grows in situ on the silica surface. At high temperatures, magnesium hydroxide can decompose into water vapor and magnesium oxide and absorb a large amount of heat, while releasing non-flammable water vapor, diluting the concentration of flammable gas, reducing the flame temperature, and increasing the oxygen index of the corrugated paper.

[0030] 4. In this invention, the boron quantum dots in the boron quantum dot modified titanium dioxide can form a strong physical adsorption with the corrugated paper fibers, improve the bonding force between the fibers, and thus enhance the stability of the overall structure. Titanium dioxide has high hardness and good weather resistance, and can fill the gaps between paper fibers to provide additional structural support. The edge crush strength of the corrugated paper is improved through the combined effect of boron quantum dots and titanium dioxide.

[0031] 5. The modified hydroxyethyl cellulose of the present invention contains zwitterionic polymers, which can reduce the capillary effect inside the corrugated paper and inhibit the absorption of moisture by changing the microstructure of the corrugated paper surface; at the same time, the modified hydroxyethyl cellulose, together with polyurethane, can form a hydrophobic barrier on the surface of the corrugated paper, effectively reducing the water absorption of the paper. Detailed Implementation

[0032] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] The sources of some components in the examples and comparative examples are as follows:

[0034] Corrugated core paper, purchased from Lee & Man Paper Manufacturing Co., Ltd.

[0035] Commercially available silica sol, product number sy07, was purchased from Qingdao Shuoyuan Silica Technology Co., Ltd.

[0036] Sodium hydroxide, CAS No. 1310-73-2, was purchased from Sinopharm Chemical Reagent Co., Ltd.

[0037] Carboxymethyl cellulose, CAS No. 9004-32-4, was purchased from Sinopharm Chemical Reagent Co., Ltd.

[0038] Hydroxypropyl methylcellulose, CAS No. 9004-65-3, was purchased from Sinopharm Chemical Reagent Co., Ltd.

[0039] Titanium dioxide, CAS No. 13463-67-7, was purchased from Shanghai Maclean Biochemical Technology Co., Ltd.

[0040] Polyurethane, model AH-1610, was purchased from Anhui Dawei Huatai New Material Technology Co., Ltd.

[0041] Hydroxyethyl cellulose I, product number H104791, with a viscosity of 1100 mPa·s, was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0042] Hydroxyethyl cellulose II, product number H104786, with a viscosity of 200 mPa·s, was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0043] Hydroxyethyl cellulose III, product number H104788, with a viscosity of 4000 mPa·s, was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0044] Ethyl orthosilicate, CAS No. 78-10-4, Shanghai Aladdin Biochemical Technology Co., Ltd.

[0045] Paraffin wax, product number 4100511, was purchased from Shandong Yousuo Chemical Technology Co., Ltd.

[0046] Magnesium chloride, CAS number 7786-30-3, was purchased from Shanghai Jizhi Biochemical Technology Co., Ltd.

[0047] Ammonium pentaborate, CAS No. 12007-89-5, purchased from Merck Chemical Company;

[0048] Boric acid, CAS No. 10043-35-3, was purchased from Sinopharm Chemical Reagent Co., Ltd.

[0049] Hydrazine hydrate, CAS No. 7803-57-8, purchased from Sigma-Aldrich (Shanghai) Trading Co., Ltd.

[0050] Tetrabutyl titanate, CAS No. 5593-70-4, was purchased from Shanghai Maclean Biochemical Technology Co., Ltd.

[0051] Cerium ammonium nitrate, item number C3654, was purchased from Sigma-Aldrich (Shanghai) Trading Co., Ltd.

[0052] [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide, CAS No. 3637-26-1, purchased from Sinopharm Chemical Reagent Co., Ltd.

[0053] 2-Acrylamido-2-methylpropanesulfonic acid, CAS No. 15214-89-8, purchased from Shanghai Huayuan Century Trading Co., Ltd.;

[0054] Sodium chloride, CAS No. 7647-14-5, was purchased from Sinopharm Chemical Reagent Co., Ltd.

[0055] Dimethyl diallyl ammonium chloride, CAS No. 7398-69-8, was purchased from Sinopharm Chemical Reagent Co., Ltd.

[0056] Potassium persulfate, CAS No. 7727-21-1, purchased from Sinopharm Chemical Reagent Co., Ltd.

[0057] Example 1

[0058] This embodiment provides a high-strength water-resistant corrugated paper, which includes corrugated core paper and a functional coating applied to the surface of the corrugated core paper. The corrugated core paper is modified by impregnation with an impregnation solution.

[0059] The corrugated paper is made by the following steps:

[0060] Preparation of boron quantum dot modified titanium dioxide: (1) By weight, 4 parts ammonium pentaborate and 2 parts boric acid were added to 25 parts deionized water and stirred for 2 hours. The mixture was placed under an argon atmosphere for hydrothermal reaction (reaction temperature was 190℃ and reaction time was 10 hours). After the reaction was completed, the mixture was cooled to room temperature, 2 parts hydrazine hydrate were added and stirred for 2 hours. The mixture was then centrifuged to obtain the supernatant and freeze-dried to obtain boron quantum dots. (2) By weight, 80 parts of anhydrous ethanol, 40 parts of deionized water, 4 parts of boron quantum dots and 10 parts of 20% hydrochloric acid solution were mixed and stirred for 20 min to obtain solution A; 80 parts of tetrabutyl titanate were added to 100 parts of anhydrous ethanol and stirred for 30 min, then the pH was adjusted to 3.6 with 20% hydrochloric acid solution and stirred for 30 min to obtain solution B; 100 parts of solution A were added to 120 parts of solution B and stirred for 60 min, then 40 parts of deionized water were added and stirred for 4 h to form a gel, which was allowed to stand at room temperature for 12 h, then dried at 80 °C for 20 h, transferred to a tube furnace and calcined at 500 °C for 2 h, and cooled to room temperature to obtain boron quantum dot modified titanium dioxide.

[0061] Preparation of coating: (1) By weight, 24 parts of hydroxyethyl cellulose I (viscosity of 1100 mPa·s) were added to 110 parts of deionized water and stirred for 3 h under nitrogen atmosphere. 8 parts of cerium ammonium nitrate and 14 parts of [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide were added at 40 °C. The pH was adjusted to 7.4 and the reaction was carried out for 6 h. After the reaction was completed, acetone was used for precipitation separation to obtain the precipitate. 40 parts of 2-acrylamido-2-methylpropanesulfonic acid and 14 parts of sodium chloride were added to 220 parts of deionized water and stirred for 40 min. Then, 45 parts of dimethyl diallyl ammonium chloride and 30 parts of the aforementioned precipitate were added and stirred for 3 h to obtain a mixture. The mixture was transferred to a reaction vessel and, under nitrogen atmosphere protection, 4 parts of potassium persulfate were added at 84 °C and the reaction was carried out for 6 h. After the reaction was completed, the mixture was cooled to room temperature, dried, and pulverized to obtain modified hydroxyethyl cellulose. (2) By weight, 6 parts of acetic acid and 70 parts of deionized water are mixed evenly, and then 100 parts of polyurethane, 3 parts of methanol and 8 parts of modified hydroxyethyl cellulose are added and stirred for 6 hours to obtain the coating.

[0062] Step S1: By weight, mix 20 parts of tetraethyl orthosilicate, 10 parts of paraffin, 24 parts of anhydrous ethanol and 24 parts of deionized water evenly, stir at 48°C for 20 min, adjust the pH to 4.8 with hydrochloric acid and stir for 4 h, then add 30 parts of magnesium chloride solution with a molar concentration of 0.3 mol / L, stir at 60°C for 4 h, then add ammonia water dropwise to adjust the pH to 7.8 and stir for 2 h to obtain modified silica sol;

[0063] Step S2: By weight, add 6 parts of sodium hydroxide to 100 parts of the modified silica sol, stir at 80°C for 60 min, then add 6 parts of methylcellulose (4 parts of carboxymethylcellulose and 2 parts of hydroxypropyl methylcellulose) and 3 parts of boron quantum dot modified titanium dioxide and continue stirring for 40 min to obtain the impregnation solution.

[0064] Step S3: Immerse the corrugated core paper in the impregnation solution at 60℃ for 20s, and then dry it in a constant temperature drying oven at 60℃ for 50min to obtain the impregnated corrugated core paper.

[0065] Step S4: Apply a coating to the impregnated corrugated core paper using a coating agent (coating amount: 50 g / m²). 2 After the coating process is completed, the paper is first left to stand at room temperature for 20 minutes, then cured at 104℃ for 70 minutes, and finally processed by corrugated rollers to obtain high-strength water-resistant corrugated paper.

[0066] Example 2

[0067] This embodiment provides a high-strength water-resistant corrugated paper, which includes corrugated core paper and a functional coating applied to the surface of the corrugated core paper. The corrugated core paper is modified by impregnation with an impregnation solution.

[0068] The corrugated paper is made by the following steps:

[0069] Preparation of boron quantum dot modified titanium dioxide: (1) By weight, 2 parts ammonium pentaborate and 1 part boric acid were added to 20 parts deionized water and stirred for 1 hour. The mixture was placed under an argon atmosphere for hydrothermal reaction (reaction temperature was 180℃ and reaction time was 12 hours). After the reaction was completed, the mixture was cooled to room temperature, 1 part hydrazine hydrate was added and stirred for 1 hour. The mixture was then centrifuged to obtain the supernatant and freeze-dried to obtain boron quantum dots. (2) By weight, 60 parts of anhydrous ethanol, 20 parts of deionized water, 2 parts of boron quantum dots and 8 parts of 30% hydrochloric acid solution were mixed and stirred for 10 min to obtain solution A; 60 parts of tetrabutyl titanate were added to 90 parts of anhydrous ethanol and stirred for 20 min, then the pH was adjusted to 3.2 with 30% hydrochloric acid solution and stirred for 15 min to obtain solution B; 80 parts of solution A were added to 100 parts of solution B and stirred for 40 min, then 20 parts of deionized water were added and stirred for 2 h to form a gel, which was allowed to stand at room temperature for 10 h, then dried at 70 °C for 22 h, transferred to a tube furnace and calcined at 480 °C for 4 h, and cooled to room temperature to obtain boron quantum dot modified titanium dioxide.

[0070] Preparation of coating: (1) By weight, 20 parts of hydroxyethyl cellulose I (viscosity of 1100 mPa.s) were added to 100 parts of deionized water and stirred for 1 h under nitrogen atmosphere. 6 parts of cerium ammonium nitrate and 10 parts of [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide were added at 36°C. The pH was adjusted to 7.2 and the reaction was carried out for 4 h. After the reaction was completed, acetone was used for precipitation separation to obtain the precipitate. 36 parts of 2-acrylamido-2-methylpropanesulfonic acid and 10 parts of sodium chloride were added to 200 parts of deionized water and stirred for 30 min. Then, 40 parts of dimethyl diallyl ammonium chloride and 20 parts of the aforementioned precipitate were added and stirred for 1 h to obtain a mixture. The mixture was transferred to a reaction vessel and, under nitrogen atmosphere protection, 2 parts of potassium persulfate were added at 80°C and the reaction was carried out for 8 h. After the reaction was completed, the mixture was cooled to room temperature, dried, and pulverized to obtain modified hydroxyethyl cellulose. (2) By weight, mix 4 parts acetic acid and 60 parts deionized water evenly, then add 90 parts polyurethane, 1 part methanol and 4 parts modified hydroxyethyl cellulose and stir for 4 hours to obtain the coating.

[0071] Step S1: By weight, mix 10 parts tetraethyl orthosilicate, 6 parts paraffin, 20 parts anhydrous ethanol and 20 parts deionized water evenly, stir at 46℃ for 30 min, adjust the pH to 4.2 with hydrochloric acid and stir for 2 h, then add 20 parts magnesium chloride solution with a molar concentration of 0.1 mol / L, stir at 54℃ for 6 h, then add ammonia water dropwise to adjust the pH to 7.4 and stir for 1 h to obtain modified silica sol;

[0072] Step S2: By weight, add 4 parts of sodium hydroxide to 90 parts of the modified silica sol, stir at 70°C for 60 min, then add 4 parts of methylcellulose (2 parts of carboxymethylcellulose and 2 parts of hydroxypropyl methylcellulose) and 1 part of boron quantum dot modified titanium dioxide and continue stirring for 30 min to obtain the impregnation solution.

[0073] Step S3: Immerse the corrugated core paper in the impregnation solution at 50℃ for 20s, and then dry it in a constant temperature drying oven at 56℃ for 60min to obtain the impregnated corrugated core paper.

[0074] Step S4: Coat the impregnated corrugated core paper with a coating (coating amount 40g / m²). 2 After the coating process is completed, the paper is first left to stand at room temperature for 10 minutes, then cured at 100°C for 80 minutes, and finally processed by corrugated rollers to obtain high-strength water-resistant corrugated paper.

[0075] Example 3

[0076] This embodiment provides a high-strength water-resistant corrugated paper, which includes corrugated core paper and a functional coating applied to the surface of the corrugated core paper. The corrugated core paper is modified by impregnation with an impregnation solution.

[0077] The corrugated paper is made by the following steps:

[0078] Preparation of boron quantum dot modified titanium dioxide: (1) By weight, 3 parts ammonium pentaborate and 1 part boric acid were added to 22 parts deionized water and stirred for 1 hour. The mixture was placed under an argon atmosphere for hydrothermal reaction (reaction temperature was 185℃ and reaction time was 11 hours). After the reaction was completed, the mixture was cooled to room temperature, 1 part hydrazine hydrate was added and stirred for 1 hour. The mixture was then centrifuged to obtain the supernatant and freeze-dried to obtain boron quantum dots. (2) By weight, 70 parts of anhydrous ethanol, 30 parts of deionized water, 3 parts of boron quantum dots and 9 parts of 25% hydrochloric acid solution were mixed and stirred for 15 min to obtain solution A; 70 parts of tetrabutyl titanate were added to 95 parts of anhydrous ethanol and stirred for 25 min, then the pH was adjusted to 3.4 with 25% hydrochloric acid solution and stirred for 20 min to obtain solution B; 90 parts of solution A were added to 110 parts of solution B and stirred for 50 min, then 30 parts of deionized water were added and stirred for 3 h to form a gel, which was allowed to stand at room temperature for 11 h, then dried at 75 °C for 21 h, transferred to a tube furnace and calcined at 490 °C for 3 h, and cooled to room temperature to obtain boron quantum dot modified titanium dioxide.

[0079] Preparation of coating: (1) By weight, 22 parts of hydroxyethyl cellulose I (viscosity of 1100 mPa.s) were added to 105 parts of deionized water and stirred for 2 h under nitrogen atmosphere. 7 parts of cerium ammonium nitrate and 12 parts of [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide were added at 38°C. The pH was adjusted to 7.3 and the reaction was carried out for 5 h. After the reaction was completed, acetone was used for precipitation separation to obtain the precipitate. 38 parts of 2-acrylamido-2-methylpropanesulfonic acid and 12 parts of sodium chloride were added to 210 parts of deionized water and stirred for 35 min. 42 parts of dimethyl diallyl ammonium chloride and 25 parts of the aforementioned precipitate were added and stirred for 2 h to obtain a mixture. The mixture was transferred to a reaction vessel and, under nitrogen atmosphere protection, 3 parts of potassium persulfate were added at 82°C and the reaction was carried out for 7 h. After the reaction was completed, the mixture was cooled to room temperature, dried, and pulverized to obtain modified hydroxyethyl cellulose. (2) By weight, 5 parts of acetic acid and 65 parts of deionized water are mixed evenly, and then 95 parts of polyurethane, 2 parts of methanol and 6 parts of modified hydroxyethyl cellulose are added and stirred for 5 hours to obtain the coating.

[0080] Step S1: By weight, mix 15 parts tetraethyl orthosilicate, 8 parts paraffin, 22 parts anhydrous ethanol and 22 parts deionized water evenly, stir at 47°C for 25 min, adjust the pH to 4.5 with hydrochloric acid and stir for 3 h, then add 25 parts magnesium chloride solution with a molar concentration of 0.2 mol / L, stir at 58°C for 5 h, then add ammonia water dropwise to adjust the pH to 7.6 and stir for 1 h to obtain modified silica sol;

[0081] Step S2: By weight, add 5 parts of sodium hydroxide to 95 parts of the modified silica sol, stir at 75°C for 55 min, then add 5 parts of methylcellulose (3 parts of carboxymethylcellulose and 2 parts of hydroxypropyl methylcellulose) and 2 parts of boron quantum dot modified titanium dioxide and continue stirring for 35 min to obtain the impregnation solution.

[0082] Step S3: Immerse the corrugated core paper in the impregnation solution at 55℃ for 15s, and then dry it in a constant temperature drying oven at 58℃ for 55min to obtain the impregnated corrugated core paper.

[0083] Step S4: Coat the impregnated corrugated core paper with a coating (coating amount 45g / m²). 2 After the coating process is completed, the paper is first left to stand at room temperature for 15 minutes, then cured at 102℃ for 75 minutes, and finally processed by corrugated rollers to obtain high-strength water-resistant corrugated paper.

[0084] Comparative Example 1

[0085] The difference between this comparative example and Example 1 is that commercially available silica sol (product number sy07, purchased from Qingdao Shuoyuan Silica Technology Co., Ltd.) was used instead of modified silica sol.

[0086] Comparative Example 2

[0087] The difference between this comparative example and Example 1 is that the amount of carboxymethyl cellulose in the impregnation solution is changed to 5 parts, and the amount of hydroxypropyl methyl cellulose is changed to 1 part.

[0088] Comparative Example 3

[0089] The difference between this comparative example and Example 1 is that the amount of carboxymethyl cellulose in the impregnation solution is changed to 2 parts, and the amount of hydroxypropyl methyl cellulose is changed to 4 parts.

[0090] Comparative Example 4

[0091] The difference between this comparative example and Example 1 is that commercially available titanium dioxide (CAS No. 13463-67-7, purchased from Shanghai McLean Biochemical Technology Co., Ltd.) was used instead of boron quantum dot modified titanium dioxide.

[0092] Comparative Example 5

[0093] The difference between this comparative example and Example 1 is that hydroxyethyl cellulose I is used instead of modified hydroxyethyl cellulose.

[0094] Comparative Example 6

[0095] The difference between this comparative example and Example 1 is that hydroxyethyl cellulose II was used instead of hydroxyethyl cellulose I in the preparation of modified hydroxyethyl cellulose.

[0096] Comparative Example 7

[0097] The difference between this comparative example and Example 1 is that hydroxyethyl cellulose III was used instead of hydroxyethyl cellulose I in the preparation of modified hydroxyethyl cellulose.

[0098] Performance testing

[0099] The corrugated paper from the above examples and comparative examples was subjected to the following tests:

[0100] (1) Edge pressure strength test

[0101] The edge crush strength was tested in accordance with the requirements of GB / T 2679.17-1997 Determination of edge crush strength of corrugated board (edge ​​reinforcement method).

[0102] (2) Oxygen Index Test

[0103] The oxygen index was tested in accordance with the requirements of GB / T 5454-1997 "Test for Burning Performance of Textiles - Oxygen Index Method".

[0104] (3) Water absorption test

[0105] The water absorption was tested in accordance with the requirements of GB / T 461.3-2005 Determination of water absorption of paper and paperboard (immersion method).

[0106] The test results are shown in Table 1.

[0107] Table 1 Performance Test Results

[0108] Edge compressive strength (kN / m) Oxygen Index (LOI) <![CDATA[Water absorption (g / m 2 )]]> Example 1 7.46 32.9 4.85 Example 2 7.28 32.2 4.93 Example 3 7.35 32.6 4.89 Comparative Example 1 5.19 24.3 8.63 Comparative Example 2 6.54 27.8 6.27 Comparative Example 3 6.61 28.4 6.21 Comparative Example 4 5.32 25.1 8.45 Comparative Example 5 5.25 24.7 8.56 Comparative Example 6 6.73 29.2 6.08 Comparative Example 7 6.68 28.9 6.13

[0109] The performance test results above show that the corrugated paper of Examples 1-2 has the best overall performance, with an edge crush strength of 7.28–7.46 kN / m, an oxygen index (LOI) of 32.2–32.9, and a water absorption of 4.85–4.93 g / m³. 2 This is mainly because it uses impregnation liquid and coating to comprehensively treat corrugated core paper, and uses modified silica sol and boron quantum dot modified titanium dioxide in the impregnation liquid, while modifying hydroxyethyl cellulose in the coating, which significantly increases edge crush strength, improves oxygen index and effectively reduces water absorption.

[0110] The comparative examples, lacking the necessary technical solutions, showed significantly inferior performance compared to the examples. Compared to Example 1, Comparative Example 1 used commercially available silica sol instead of modified silica sol, resulting in reduced edge crush strength, lower oxygen index, and increased water absorption. In Comparative Example 2, the amount of carboxymethyl cellulose in the impregnation solution was changed to 5 parts and hydroxypropyl methyl cellulose to 1 part. Excessive carboxymethyl cellulose resulted in poor compounding, leading to reduced edge crush strength, lower oxygen index, and increased water absorption. In Comparative Example 3, the amount of carboxymethyl cellulose in the impregnation solution was changed to 2 parts and hydroxypropyl methyl cellulose to 4 parts. Insufficient carboxymethyl cellulose resulted in poor compounding, leading to reduced edge crush strength, lower oxygen index, and increased water absorption. Compared to Example 1… In Comparative Example 4, commercially available titanium dioxide was used instead of boron quantum dot-modified titanium dioxide, resulting in decreased edge crush strength, a lower oxygen index, and increased water absorption. Compared to Example 1, Comparative Example 5 used hydroxyethyl cellulose I instead of modified hydroxyethyl cellulose, resulting in decreased edge crush strength, a lower oxygen index, and increased water absorption. Compared to Example 1, Comparative Example 6 used hydroxyethyl cellulose II instead of hydroxyethyl cellulose I for the preparation of modified hydroxyethyl cellulose. Due to the low viscosity of hydroxyethyl cellulose II, the modification effect was poor, resulting in decreased edge crush strength, a lower oxygen index, and increased water absorption. Compared to Example 1, Comparative Example 7 used hydroxyethyl cellulose III instead of hydroxyethyl cellulose I for the preparation of modified hydroxyethyl cellulose. Due to the high viscosity of hydroxyethyl cellulose III, the modification effect was poor, resulting in decreased edge crush strength, a lower oxygen index, and increased water absorption. These experimental results further demonstrate the importance of the technical solutions defined in this invention for their technical effects.

[0111] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A high-strength water-resistant corrugated paper, characterized by, The high-strength water-resistant corrugated paper comprises a corrugated core paper and a functional coating applied to the surface of the corrugated core paper, wherein the corrugated core paper is subjected to a modification treatment by impregnation with an impregnation liquid; The corrugated paper is prepared by the following steps: Step S1: uniformly mix 10-20 parts of tetraethyl orthosilicate, 6-10 parts of paraffin wax, 20-24 parts of anhydrous ethanol and 20-24 parts of deionized water by weight, stir at 46-48 DEG C for 20-30 min, adjust the pH to 4.2-4.8 with hydrochloric acid and stir for 2-4 h, then add 20-30 parts of a magnesium chloride solution with a molar concentration of 0.1-0.3 mol / L, stir at 54-60 DEG C for 4-6 h, dropwise add ammonia water to adjust the pH to 7.4-7.8 and stir for 1-2 h to obtain a modified silica sol; Step S2: add 4-6 parts of sodium hydroxide to 90-100 parts of the modified silica sol by weight, stir at 70-80 DEG C for 50-60 min, then add 4-6 parts of methyl cellulose and 1-3 parts of titanium dioxide and continue to stir for 30-40 min to obtain an impregnation liquid; Step S3: immerse the corrugated core paper in the impregnation liquid at 50-60 DEG C for 10-20 s, then dry in a constant-temperature air drying oven at 56-60 DEG C for 50-60 min to obtain the corrugated core paper after impregnation treatment; Step S4: perform coating treatment on the corrugated core paper after impregnation treatment using a coating, after the coating treatment is completed, first stand still at room temperature for 10-20 min, then cure at 100-104 DEG C for 70-80 min, and finally process by a corrugating roller to obtain the high-strength water-resistant corrugated paper; The titanium dioxide is boron quantum dot modified titanium dioxide; The preparation method of the boron quantum dot modified titanium dioxide comprises: uniformly mix 60-80 parts of anhydrous ethanol, 20-40 parts of deionized water, 2-4 parts of boron quantum dots and 8-10 parts of a hydrochloric acid solution with a mass concentration fraction of 20-30% by weight and stir for 10-20 min to obtain A liquid; add 60-80 parts of tetrabutyl titanate to 90-100 parts of anhydrous ethanol and stir for 20-30 min, then adjust the pH to 3.2-3.6 with the hydrochloric acid solution with a mass concentration fraction of 20-30% and stir for 15-30 min to obtain B liquid; add 80-100 parts of the A liquid to 100-120 parts of the B liquid and stir for 40-60 min, then add 20-40 parts of deionized water and stir for 2-4 h to form a gel, stand still at room temperature for 10-12 h, then dry at 70-80 DEG C for 20-22 h, transfer to a tube furnace and calcine at 480-500 DEG C for 2-4 h, and cool to room temperature to obtain the boron quantum dot modified titanium dioxide; The preparation method of the coating comprises: uniformly mix 4-6 parts of acetic acid and 60-70 parts of deionized water by weight, then add 90-100 parts of polyurethane, 1-3 parts of methanol and 4-8 parts of hydroxyethyl cellulose and stir for 4-6 h to obtain the coating; The hydroxyethyl cellulose is modified hydroxyethyl cellulose; The preparation method of the modified hydroxyethyl cellulose comprises the following steps: adding 20-24 parts of hydroxyethyl cellulose into 100-110 parts of deionized water in terms of weight, stirring for 1-3 hours under a nitrogen atmosphere, adding 6-8 parts of cerium ammonium nitrate and 10-14 parts of [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide at 36-40 DEG C, adjusting pH to 7.2-7.4, reacting for 4-6 hours, precipitating and separating by using acetone after the reaction is completed, and obtaining a precipitate; adding 36-40 parts of 2-acrylamido-2-methylpropanesulfonic acid and 10-14 parts of sodium chloride into 200-220 parts of deionized water, stirring for 30-40 minutes, then adding 40-45 parts of dimethyldiallylammonium chloride and 20-30 parts of the aforementioned precipitate, stirring for 1-3 hours to obtain a mixed solution, transferring the mixed solution into a reaction kettle, adding 2-4 parts of potassium persulfate under the protection of a nitrogen atmosphere at 80-84 DEG C, reacting for 6-8 hours, cooling to room temperature after the reaction is completed, drying, crushing, and obtaining the modified hydroxyethyl cellulose.

2. The high-strength water-resistant corrugated paper according to claim 1, wherein, The methyl cellulose is carboxymethyl cellulose and hydroxypropyl methyl cellulose; and the mass ratio of the carboxymethyl cellulose to the hydroxypropyl methyl cellulose is (1-2):

1.

3. The high-strength water-resistant corrugated paper according to claim 1, wherein, The preparation method of the boron quantum dots comprises the following steps: adding 2-4 parts of ammonium pentaborate and 1-2 parts of boric acid into 20-25 parts of deionized water in terms of weight, stirring for 1-2 hours, carrying out hydrothermal reaction under an argon atmosphere, cooling to room temperature after the reaction is completed, adding 1-2 parts of hydrazine hydrate, stirring for 1-2 hours, then centrifuging to obtain supernatant, and freeze-drying to obtain the boron quantum dots.

4. The high-strength water-resistant corrugated paper according to claim 3, wherein, The reaction temperature of the hydrothermal reaction is 180-190 DEG C, and the reaction time is 10-12 hours.

5. The high-strength water-resistant corrugated paper according to claim 1, wherein The viscosity of the hydroxyethyl cellulose is 800-1200 mPa.s.

6. The high-strength water-resistant corrugated paper according to claim 1, wherein, The coating amount in the coating treatment is 40-50 g / m2.

7. Use of the high-strength water-resistant corrugated paper according to any one of claims 1-6 in a waterproof carton.