Preparation method of high-strength water-resistant special functional paperboard

Abstract

The invention discloses a preparation method of a high-strength water-resistant special functional paperboard, and belongs to the technical field of papermaking, the high-strength water-resistant special functional paperboard sequentially comprises a surface sizing layer, a surface paper layer, a core paper layer, a bottom paper layer and a bottom sizing layer from top to bottom, and the surface paper layer, the core paper layer and the bottom paper layer are made of waste paper pulp. The surface sizing layer and the bottom sizing layer are made of environment-friendly glue, through the surface paper layer, the core paper layer and the bottom paper layer, the functional paper has higher paperboard physical strength and better water resistance, and the functional paper is environmentally friendly, efficient and remarkable in superiority.

Description

Technical Field

[0001] This invention relates to the field of papermaking technology, specifically to a method for preparing a high-strength, water-resistant functional paperboard. Background Technology

[0002] Papermaking is an ancient and important technology that plays a vital role in our lives and work. With the development of science and technology, papermaking technology is constantly advancing, and various new papermaking equipment and methods have been developed to improve paper quality and yield. Among these, functional paperboard is an important paper product, possessing properties such as high strength and water resistance, and is widely used in packaging, construction, and decoration. However, traditional methods for preparing functional paperboard have some problems, such as insufficient inter-fiber bonding, poor paper uniformity, and inadequate water resistance.

[0003] Existing technological solutions: To address these issues, existing technologies primarily improve paper performance by adding chemical additives. For example, adding wet strength agents can increase the wet strength of paper, and adding water-repellent agents can improve its water resistance. Additionally, some technologies improve paper quality by altering the papermaking process, such as increasing the beating degree and adjusting the operating parameters of the paper machine.

[0004] Existing technological challenges: While existing technologies improve paper performance, they often introduce new problems. For example, adding chemical additives may pollute the environment and potentially affect human health. Furthermore, altering the papermaking process may increase production costs and reduce efficiency. Therefore, how to improve paper performance through improved papermaking processes without adding chemical additives is a pressing issue in the field of papermaking technology. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a method for preparing a high-strength, water-resistant functional paperboard.

[0006] The objective of this invention can be achieved through the following technical solutions: A method for preparing a high-strength, water-resistant functional paperboard, wherein the high-strength, water-resistant functional paperboard comprises, from top to bottom, a top sizing layer, a face paper layer, a core paper layer, a bottom paper layer, and a bottom sizing layer. The face paper layer, core paper layer, and bottom paper layer are made from waste paper pulp, and the top sizing layer and bottom sizing layer are made from environmentally friendly adhesives. The preparation method includes the following steps: Step 1, Pulping: Waste paper is processed through shredding, sand removal, coarse selection, fine selection, concentration, thermal dispersion, grading and concentration to obtain medium fiber pulp, long fiber pulp and short fiber pulp; Step 2, Pulping: The medium fiber pulp, long fiber pulp and short fiber pulp obtained in Step 1 are pulped separately using a disc mill; Step 3, Pulping: Add dye, dry strength agent, AKD, aluminum sulfate, and retention aid to the medium fiber pulp after beating in sequence to prepare the top slurry; add dry strength agent, AKD, aluminum sulfate, and retention aid to the long fiber pulp after beating in sequence to prepare the core slurry; add dry strength agent, AKD, aluminum sulfate, and retention aid to the short fiber pulp after beating in sequence to prepare the bottom slurry. Step 4: Papermaking: The face pulp, core pulp and bottom pulp are formed and dewatered through a three-layer wire forming machine to form the face paper layer, core paper layer and bottom paper layer in sequence, making a wet paper sheet with a concentration of 18-25%. After pressing, a press paper with a concentration of 48-52% is obtained. After drying, a base paper with a concentration of 80-85% is obtained. Step 5: Apply environmentally friendly adhesive to both sides of the base paper using a sizing machine to form a top sizing layer and a bottom sizing layer. The coating amount is 1-4 g / m². 2 .

[0007] Furthermore, in the flour paste, the weight ratio of dye, dry strength agent, AKD, aluminum sulfate, retention aid and medium fiber pulp after beating is 0.03-0.05%: 1.2-1.5%: 0.1-0.2%: 1%: 0.02-0.03%: 1.

[0008] Furthermore, in the core pulp, the weight ratio of dry strength agent, AKD, aluminum sulfate, retention aid and long fiber pulp after beating is 1.2-1.5%: 0.1-0.2%: 1%: 0.02-0.03%: 1.

[0009] Furthermore, in the base slurry, the weight ratio of dry strength agent, AKD, aluminum sulfate, retention aid to the beaten short fiber pulp is 1.2-1.5%: 0.1-0.2%: 1%: 0.02-0.03%: 1.

[0010] Furthermore, the environmentally friendly adhesive is prepared through the following steps: Step S1: Add p-hydroxybenzaldehyde to a three-necked flask containing anhydrous ethanol, add sodium hydroxide, stir at room temperature for 30 min, then add 8-bromo-1-octene, stir magnetically and heat to 65-70℃, reflux for 12-16 h, filter under reduced pressure after the reaction is complete, and rotary evaporate (to remove solvent) to obtain intermediate 1. In step S1, the hydroxyl group on p-hydroxybenzaldehyde reacts with the bromine atom on 8-bromo-1-octene to prepare intermediate 1; Step S2: Add benzoyl hydrazide and intermediate 1 to acetonitrile, add glacial acetic acid, heat to 80-85℃ under nitrogen atmosphere, stir at a constant speed and react for 24h. After the reaction is completed, filter to obtain crude product, wash in isopropanol, dry and obtain functional monomer. In step S2, glacial acetic acid acts as a catalyst, and the aldehyde group on intermediate 1 reacts with the amino group on benzoyl hydrazine to prepare a functional monomer. This functional monomer has a Schiff base structure formed by the reaction, which can endow the monomer with certain antibacterial properties. It also has a long-chain alkyl group remaining from the reaction of 8-bromo-1-octene, which can bring hydrophobic properties to the monomer. Moreover, the carbon-carbon double bond retained in the structure can copolymerize with the starch structure, making it easy to integrate into the starch structure.

[0011] Step S3: Add cassava starch to deionized water, heat to 45-50℃, stir at a constant speed for 10 minutes to obtain a suspension, then add concentrated hydrochloric acid, keep warm and react for 2 hours. After the reaction, add 25% sodium hydroxide aqueous solution to adjust the pH until the system pH=5-5.5, add ammonium persulfate and functional monomer, stir at a constant speed and react for 4-6 hours, add sodium metaphosphate for crosslinking for 30-45 minutes, then add urea and sodium dodecyl sulfate in sequence, heat to 90℃, gelatinize for 30 minutes to obtain environmentally friendly adhesive.

[0012] In step S3, starch is used as the matrix, sodium metaphosphate as the crosslinking agent, and ammonium persulfate as the initiator. The carbon-carbon double bonds on the added functional monomer can undergo a grafting reaction with starch. The long-chain alkyl groups on the functional monomer can endow the starch structure with hydrophobic properties, preventing water from entering the wood and breaking hydrogen bonds after the starch-based adhesive is soaked in water, thus preventing the starch adhesive from becoming less durable. The introduced Schiff base structure can endow the adhesive with certain antibacterial properties, so that the prepared environmentally friendly adhesive can bring certain anti-mildew and antibacterial properties when used to coat paper.

[0013] Furthermore, in step S1, the ratio of p-hydroxybenzaldehyde, sodium hydroxide, 8-bromo-1-octene, and anhydrous ethanol is controlled to be 0.1-0.2 mol: 2-5 g: 0.1-0.2 mol: 100 mL.

[0014] Furthermore, in step S2, the ratio of benzoyl hydrazide, intermediate 1, glacial acetic acid and acetonitrile is controlled to be 0.1-0.2 mol: 0.1-0.2 mol: 0.2-0.3 mL: 100 mL.

[0015] Furthermore, in step S3, the ratio of cassava starch, concentrated hydrochloric acid, ammonium persulfate, functional monomer, sodium metaphosphate, urea, sodium dodecyl sulfate, and deionized water is controlled as follows: 15-20g: 0.5-0.8mL: 0.3-0.5g: 3-5g: 1-1.5g: 0.5-0.8g: 0.5-0.8g: 50mL.

[0016] The beneficial effects of this invention are as follows: This invention prepares a high-strength, water-resistant functional paper. Through the face paper layer, core paper layer, and back paper layer, the functional paper has higher physical strength and better water resistance. It is also environmentally friendly and efficient, with significant advantages. In addition, an environmentally friendly adhesive is prepared using starch as a matrix, sodium metaphosphate as a crosslinking agent, and ammonium persulfate as an initiator. The carbon-carbon double bonds added to the functional monomer can undergo a grafting reaction with starch. The long-chain alkyl groups on the functional monomer can give the starch structure hydrophobic properties, preventing water from entering the wood and breaking hydrogen bonds after soaking in water, thus preventing the starch-based adhesive from becoming less durable. The introduced Schiff base structure can give the adhesive certain antibacterial properties, so that the prepared environmentally friendly adhesive can bring certain anti-mildew and antibacterial properties when used to coat paper. Detailed Implementation

[0017] 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.

[0018] Example 1: A method for preparing a high-strength, water-resistant functional paperboard, wherein the high-strength, water-resistant functional paperboard comprises, from top to bottom, a top sizing layer, a face paper layer, a core paper layer, a bottom paper layer, and a bottom sizing layer. The face paper layer, core paper layer, and bottom paper layer are made from waste paper pulp, and the top sizing layer and bottom sizing layer are made from environmentally friendly adhesives. The preparation method includes the following steps: Step 1, Pulping: Waste paper is processed through shredding, sand removal, coarse selection, fine selection, concentration, thermal dispersion, grading and concentration to obtain medium fiber pulp, long fiber pulp and short fiber pulp; Step 2, Pulping: The medium fiber pulp, long fiber pulp and short fiber pulp obtained in Step 1 are pulped separately using a disc mill; Step 3, Pulping: Add dye, dry strength agent, AKD, aluminum sulfate, and retention aid to the medium fiber pulp after beating in sequence to prepare the top slurry; add dry strength agent, AKD, aluminum sulfate, and retention aid to the long fiber pulp after beating in sequence to prepare the core slurry; add dry strength agent, AKD, aluminum sulfate, and retention aid to the short fiber pulp after beating in sequence to prepare the bottom slurry. Step 4: Papermaking: The face pulp, core pulp and bottom pulp are formed and dewatered through a three-layer wire forming machine to form the face paper layer, core paper layer and bottom paper layer in sequence, making a wet paper sheet with a concentration of 18-25%. After pressing, a press paper with a concentration of 48-52% is obtained. After drying, a base paper with a concentration of 80-85% is obtained. Step 5: Apply environmentally friendly adhesive to both sides of the base paper using a sizing machine to form a top sizing layer and a bottom sizing layer. The coating amount is 1-4 g / m². 2 .

[0019] The weight ratio of basic dyes, dry strength agent polyacrylamide, AKD, aluminum sulfate, retention aid cationic polyacrylamide to the medium fiber pulp after beating is 0.03%:1.2%:0.1%:1%:0.02%:1.

[0020] In the core pulp, the weight ratio of dry strength agent polyacrylamide, AKD, aluminum sulfate, retention aid cationic polyacrylamide to the beaten long fiber pulp is 1.2%:0.1%:1%:0.02%:1.

[0021] In the base slurry, the weight ratio of dry strength agent polyacrylamide, AKD, aluminum sulfate, retention aid cationic polyacrylamide to the beaten short fiber pulp is 1.2%:0.1%:1%:0.02%:1.

[0022] The environmentally friendly adhesive is prepared through the following steps: Step S1: Add p-hydroxybenzaldehyde to a three-necked flask containing anhydrous ethanol, add sodium hydroxide, stir at room temperature for 30 min, then add 8-bromo-1-octene, stir magnetically and heat to 65℃, reflux for 12 h, filter under reduced pressure after the reaction, and rotary evaporate (to remove solvent) to obtain intermediate 1. Control the ratio of p-hydroxybenzaldehyde, sodium hydroxide, 8-bromo-1-octene and anhydrous ethanol to be 0.1 mol: 2 g: 0.1 mol: 100 mL. Step S2: Add benzoyl hydrazide and intermediate 1 to acetonitrile, add glacial acetic acid, heat to 80°C under nitrogen atmosphere, stir at a constant speed and react for 24 hours. After the reaction is completed, filter to obtain crude product, wash in isopropanol, dry to obtain functional monomer. Control the ratio of benzoyl hydrazide, intermediate 1, glacial acetic acid and acetonitrile to be 0.1 mol: 0.1 mol: 0.2 mL: 100 mL. Step S3: Add cassava starch to deionized water, heat to 45℃, and stir at a constant speed for 10 minutes to obtain a suspension. Then add concentrated hydrochloric acid, keep warm and react for 2 hours. After the reaction, add 25% sodium hydroxide aqueous solution to adjust the pH until the system pH=5-5.5. Add ammonium persulfate and functional monomer, stir at a constant speed and react for 4 hours. Add sodium metaphosphate for crosslinking for 30-45 minutes, then add urea and sodium dodecyl sulfate in sequence. Heat to 90℃ and gelatinize for 30 minutes to obtain an environmentally friendly adhesive. Control the ratio of cassava starch, concentrated hydrochloric acid, ammonium persulfate, functional monomer, sodium metaphosphate, urea, sodium dodecyl sulfate and deionized water to be 15g:0.5mL:0.3g:3g:1g:0.5g:0.5-0.8g:50mL.

[0023] Example 2: A method for preparing a high-strength, water-resistant functional paperboard, wherein the high-strength, water-resistant functional paperboard comprises, from top to bottom, a top sizing layer, a face paper layer, a core paper layer, a bottom paper layer, and a bottom sizing layer. The face paper layer, core paper layer, and bottom paper layer are made from waste paper pulp, and the top sizing layer and bottom sizing layer are made from environmentally friendly adhesives. The preparation method includes the following steps: Step 1, Pulping: Waste paper is processed through shredding, sand removal, coarse selection, fine selection, concentration, thermal dispersion, grading and concentration to obtain medium fiber pulp, long fiber pulp and short fiber pulp; Step 2, Pulping: The medium fiber pulp, long fiber pulp and short fiber pulp obtained in Step 1 are pulped separately using a disc mill; Step 3, Pulping: Add dye, dry strength agent, AKD, aluminum sulfate, and retention aid to the medium fiber pulp after beating in sequence to prepare the top slurry; add dry strength agent, AKD, aluminum sulfate, and retention aid to the long fiber pulp after beating in sequence to prepare the core slurry; add dry strength agent, AKD, aluminum sulfate, and retention aid to the short fiber pulp after beating in sequence to prepare the bottom slurry. Step 4: Papermaking: The face pulp, core pulp and bottom pulp are formed and dewatered through a three-layer wire forming machine to form the face paper layer, core paper layer and bottom paper layer in sequence, making a wet paper sheet with a concentration of 18-25%. After pressing, a press paper with a concentration of 48-52% is obtained. After drying, a base paper with a concentration of 80-85% is obtained. Step 5: Apply environmentally friendly adhesive to both sides of the base paper using a sizing machine to form a top sizing layer and a bottom sizing layer. The coating amount is 1-4 g / m². 2 .

[0024] In the pulp, the weight ratio of basic dyes, dry strength agent polyacrylamide, AKD, aluminum sulfate, retention aid cationic polyacrylamide to the medium fiber pulp after beating is 0.03-0.05%: 1.2-1.5%: 0.1-0.2%: 1%: 0.02-0.03%: 1.

[0025] In the core pulp, the weight ratio of dry strength agent polyacrylamide, AKD, aluminum sulfate, retention aid cationic polyacrylamide to the beaten long fiber pulp is 1.3%:0.15%:1%:0.02%:1.

[0026] In the base slurry, the weight ratio of dry strength agent polyacrylamide, AKD, aluminum sulfate, retention aid cationic polyacrylamide to the beaten short fiber pulp is 1.4%:0.15%:1%:0.02%:1.

[0027] The environmentally friendly adhesive is prepared through the following steps: Step S1: Add p-hydroxybenzaldehyde to a three-necked flask containing anhydrous ethanol, add sodium hydroxide, stir at room temperature for 30 min, then add 8-bromo-1-octene, stir magnetically and heat to 65-70℃, reflux for 12-16 h, filter under reduced pressure after the reaction, and rotary evaporate (to remove solvent) to obtain intermediate 1. Control the ratio of p-hydroxybenzaldehyde, sodium hydroxide, 8-bromo-1-octene and anhydrous ethanol to be 0.15 mol: 3 g: 0.15 mol: 100 mL; Step S2: Add benzoyl hydrazide and intermediate 1 to acetonitrile, add glacial acetic acid, heat to 82°C under nitrogen atmosphere, stir at a constant speed and react for 24 hours. After the reaction is completed, filter to obtain crude product, wash in isopropanol, dry to obtain functional monomer. Control the ratio of benzoyl hydrazide, intermediate 1, glacial acetic acid and acetonitrile to be 0.15mol:0.15mol:0.25mL:100mL. Step S3: Add cassava starch to deionized water, heat to 48℃, and stir at a constant speed for 10 minutes to obtain a suspension. Then add concentrated hydrochloric acid, keep warm and react for 2 hours. After the reaction, add 25% sodium hydroxide aqueous solution to adjust the pH until the system pH=5-5.5. Add ammonium persulfate and functional monomer, stir at a constant speed and react for 5 hours. Add sodium metaphosphate for crosslinking for 40 minutes, then add urea and sodium dodecyl sulfate in sequence. Heat to 90℃ and gelatinize for 30 minutes to obtain an environmentally friendly adhesive. Control the ratio of cassava starch, concentrated hydrochloric acid, ammonium persulfate, functional monomer, sodium metaphosphate, urea, sodium dodecyl sulfate and deionized water to be 18g:0.6mL:0.4g:4g:1.2g:0.6g:0.6g:50mL.

[0028] Example 3: A method for preparing a high-strength, water-resistant functional paperboard, wherein the high-strength, water-resistant functional paperboard comprises, from top to bottom, a top sizing layer, a face paper layer, a core paper layer, a bottom paper layer, and a bottom sizing layer. The face paper layer, core paper layer, and bottom paper layer are made from waste paper pulp, and the top sizing layer and bottom sizing layer are made from environmentally friendly adhesives. The preparation method includes the following steps: Step 1, Pulping: Waste paper is processed through shredding, sand removal, coarse selection, fine selection, concentration, thermal dispersion, grading and concentration to obtain medium fiber pulp, long fiber pulp and short fiber pulp; Step 2, Pulping: The medium fiber pulp, long fiber pulp and short fiber pulp obtained in Step 1 are pulped separately using a disc mill; Step 3, Pulping: Add dye, dry strength agent, AKD, aluminum sulfate, and retention aid to the medium fiber pulp after beating in sequence to prepare the top slurry; add dry strength agent, AKD, aluminum sulfate, and retention aid to the long fiber pulp after beating in sequence to prepare the core slurry; add dry strength agent, AKD, aluminum sulfate, and retention aid to the short fiber pulp after beating in sequence to prepare the bottom slurry. Step 4: Papermaking: The face pulp, core pulp and bottom pulp are formed and dewatered through a three-layer wire forming machine to form the face paper layer, core paper layer and bottom paper layer in sequence, making a wet paper sheet with a concentration of 18-25%. After pressing, a press paper with a concentration of 48-52% is obtained. After drying, a base paper with a concentration of 80-85% is obtained. Step 5: Apply environmentally friendly adhesive to both sides of the base paper using a sizing machine to form a top sizing layer and a bottom sizing layer. The coating amount is 1-4 g / m². 2 .

[0029] The weight ratio of basic dyes, dry strength agent polyacrylamide, AKD, aluminum sulfate, retention aid cationic polyacrylamide to the medium fiber pulp after beating is 0.05%: 0.5%: 0.2%: 1%: 0.03%: 1.

[0030] In the core pulp, the weight ratio of dry strength agent polyacrylamide, AKD, aluminum sulfate, retention aid cationic polyacrylamide to the beaten long fiber pulp is 1.5%:0.2%:1%:0.03%:1.

[0031] In the base slurry, the weight ratio of dry strength agent polyacrylamide, AKD, aluminum sulfate, retention aid cationic polyacrylamide to the beaten short fiber pulp is 1.5%:0.2%:1%:0.03%:1.

[0032] The environmentally friendly adhesive is prepared through the following steps: Step S1: Add p-hydroxybenzaldehyde to a three-necked flask containing anhydrous ethanol, add sodium hydroxide, stir at room temperature for 30 min, then add 8-bromo-1-octene, stir magnetically and heat to 65-70℃, reflux for 12-16 h, filter under reduced pressure after the reaction, and rotary evaporate (to remove solvent) to obtain intermediate 1. Control the ratio of p-hydroxybenzaldehyde, sodium hydroxide, 8-bromo-1-octene and anhydrous ethanol to be 0.2 mol: 5 g: 0.2 mol: 100 mL. Step S2: Add benzoyl hydrazide and intermediate 1 to acetonitrile, add glacial acetic acid, heat to 85°C under nitrogen atmosphere, stir at a constant speed and react for 24 hours. After the reaction is completed, filter to obtain crude product, wash in isopropanol, dry to obtain functional monomer, and control the ratio of benzoyl hydrazide, intermediate 1, glacial acetic acid and acetonitrile to be 0.2mol:0.2mol:0.3mL:100mL. Step S3: Add cassava starch to deionized water, heat to 50℃, and stir at a constant speed for 10 minutes to obtain a suspension. Then add concentrated hydrochloric acid, keep warm and react for 2 hours. After the reaction, add 25% sodium hydroxide aqueous solution to adjust the pH until the system pH=5-5.5. Add ammonium persulfate and functional monomer, stir at a constant speed and react for 4-6 hours. Add sodium metaphosphate for crosslinking for 30-45 minutes, then add urea and sodium dodecyl sulfate in sequence. Heat to 90℃ and gelatinize for 30 minutes to obtain an environmentally friendly adhesive. Control the ratio of cassava starch, concentrated hydrochloric acid, ammonium persulfate, functional monomer, sodium metaphosphate, urea, sodium dodecyl sulfate and deionized water to be 20g:0.8mL:0.5g:5g:1.5g:0.8g:0.8g:50mL.

[0033] Comparative Example 1: Compared with Example 1, this comparative example uses a commercially available starch-based adhesive instead of an environmentally friendly adhesive, and the rest is the same as in Example 1.

[0034] The performance of the functional papers prepared in Examples 1-3 and Comparative Example 1 was tested, and the results are shown in Table 1 below: As can be seen from Table 1 above, the paper prepared in Examples 1-3 of the present invention has excellent waterproof properties and antibacterial and antifungal properties.

[0035] The above description is merely an example and illustration of the concept of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described or use similar methods to replace them, as long as they do not deviate from the concept of the invention or exceed the scope defined in the claims, they should all fall within the protection scope of the present invention.

Claims

1. A method for preparing a high-strength, water-resistant functional paperboard, characterized in that, This high-strength, water-resistant functional paperboard consists of, from top to bottom, a top sizing layer, a face paper layer, a core paper layer, a back paper layer, and a bottom sizing layer. The face paper layer, core paper layer, and back paper layer are made from waste paper pulp, while the top sizing layer and bottom sizing layer are made with environmentally friendly adhesives. The preparation method includes the following steps: Step 1, Pulping: Waste paper is processed through shredding, sand removal, coarse selection, fine selection, concentration, thermal dispersion, grading and concentration to obtain medium fiber pulp, long fiber pulp and short fiber pulp; Step 2, Pulping: The medium fiber pulp, long fiber pulp and short fiber pulp obtained in Step 1 are pulped separately using a disc mill; Step 3, Pulping: Add dye, dry strength agent, AKD, aluminum sulfate, and retention aid to the medium fiber pulp after beating in sequence to prepare the top slurry; add dry strength agent, AKD, aluminum sulfate, and retention aid to the long fiber pulp after beating in sequence to prepare the core slurry; add dry strength agent, AKD, aluminum sulfate, and retention aid to the short fiber pulp after beating in sequence to prepare the bottom slurry. Step 4: Papermaking: The face pulp, core pulp and bottom pulp are formed and dewatered through a three-layer wire forming machine to form the face paper layer, core paper layer and bottom paper layer in sequence, making a wet paper sheet with a concentration of 18-25%. After pressing, a press paper with a concentration of 48-52% is obtained. After drying, a base paper with a concentration of 80-85% is obtained. Step 5: Apply environmentally friendly adhesive to both sides of the base paper using a sizing machine to form a top sizing layer and a bottom sizing layer. The coating amount is 1-4 g / m². 2 .

2. The method for preparing a high-strength, water-resistant functional paperboard according to claim 1, characterized in that, In the pulp, the weight ratio of dye, dry strength agent, AKD, aluminum sulfate, retention aid and medium fiber pulp after beating is 0.03-0.05%: 1.2-1.5%: 0.1-0.2%: 1%: 0.02-0.03%:

1.

3. The method for preparing a high-strength, water-resistant functional paperboard according to claim 1, characterized in that, In the core pulp, the weight ratio of dry strength agent, AKD, aluminum sulfate, retention aid and long fiber pulp after beating is 1.2-1.5%: 0.1-0.2%: 1%: 0.02-0.03%:

1.

4. The method for preparing a high-strength, water-resistant functional paperboard according to claim 1, characterized in that, In the base slurry, the weight ratio of dry strength agent, AKD, aluminum sulfate, retention aid and short fiber pulp after beating is 1.2-1.5%: 0.1-0.2%: 1%: 0.02-0.03%:

1.

5. The method for preparing a high-strength, water-resistant functional paperboard according to claim 1, characterized in that, The environmentally friendly adhesive is prepared through the following steps: Step S1: Add p-hydroxybenzaldehyde to a three-necked flask containing anhydrous ethanol, add sodium hydroxide, stir at room temperature for 30 min, then add 8-bromo-1-octene, stir magnetically and heat to 65-70℃, reflux for 12-16 h, filter under reduced pressure after the reaction is complete, and rotary evaporate (to remove solvent) to obtain intermediate 1. Step S2: Add benzoyl hydrazide and intermediate 1 to acetonitrile, add glacial acetic acid, heat to 80-85℃ under nitrogen atmosphere, stir at a constant speed and react for 24h. After the reaction is completed, filter to obtain crude product, wash in isopropanol, dry and obtain functional monomer. Step S3: Add cassava starch to deionized water, heat to 45-50℃, stir at a constant speed for 10 minutes to obtain a suspension, then add concentrated hydrochloric acid, keep warm and react for 2 hours. After the reaction, add 25% sodium hydroxide aqueous solution to adjust the pH until the system pH=5-5.5, add ammonium persulfate and functional monomer, stir at a constant speed and react for 4-6 hours, add sodium metaphosphate for crosslinking for 30-45 minutes, then add urea and sodium dodecyl sulfate in sequence, heat to 90℃, gelatinize for 30 minutes to obtain environmentally friendly adhesive.

6. The method for preparing a high-strength, water-resistant functional paperboard according to claim 5, characterized in that, In step S1, the ratio of p-hydroxybenzaldehyde, sodium hydroxide, 8-bromo-1-octene, and anhydrous ethanol is controlled to be 0.1-0.2 mol: 2-5 g: 0.1-0.2 mol: 100 mL.

7. The method for preparing a high-strength, water-resistant functional paperboard according to claim 5, characterized in that, In step S2, the ratio of benzoyl hydrazide, intermediate 1, glacial acetic acid and acetonitrile is controlled to be 0.1-0.2 mol: 0.1-0.2 mol: 0.2-0.3 mL: 100 mL.

8. The method for preparing a high-strength water-resistant functional paperboard according to claim 5, characterized in that, In step S3, the ratio of cassava starch, concentrated hydrochloric acid, ammonium persulfate, functional monomer, sodium metaphosphate, urea, sodium dodecyl sulfate, and deionized water is controlled as follows: 15-20g: 0.5-0.8mL: 0.3-0.5g: 3-5g: 1-1.5g: 0.5-0.8g: 0.5-0.8g: 50mL.

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