High-performance paper wet strength agent and preparation method thereof

Abstract

The invention provides a high-performance paper wet strength agent and a preparation method thereof, and relates to the field of paper wet strength agents. The paper wet strength agent is prepared from the following raw materials: 60 to 100 parts of triethylene tetramine, 20 to 30 parts of methacryloyloxyethyl trimethyl ammonium chloride, 10 to 20 parts of organic modified montmorillonite, 5 to 10 parts of epoxy resin, 30 to 50 parts of polyamide polyamine, 10 to 20 parts of ethylene glycol monomethyl ether, 5 to 10 parts of cationic starch, 5 to 10 parts of double-bond carboxymethyl chitosan, 1 to 5 parts of 1, 5-hexadiene diepoxide and 0.1 to 0.5 part of ammonium persulfate. And 1 to 5 parts of beta-cyclodextrin. According to the paper wet strength agent, the wet strength and the dry strength of paper can be improved, and the binding strength of the wet strength agent and paper fibers and the hydrophobicity of the paper are improved by grafting chitosan, long-chain alkyl and layered montmorillonite on a three-dimensional network structure.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of paper wet strength agent, in particular to a high-performance paper wet strength agent and a preparation method thereof. BACKGROUND

[0002] The paper wet strength agent is a kind of chemical additive for improving the mechanical strength of paper in the fully wet state. Its core function is to make the paper after being saturated with water still maintain the original dry strength of more than 15% (usually 20%-50%).

[0003] The polyamide epoxy chloropropane resin (PAE) wet strength agent does not contain formaldehyde, but there are disadvantages such as organic chlorine residue, low curing efficiency, more than 7 days curing period to reach 90% of the final wet strength, high cost and the like. Based on the organic chlorine residue problem of the PAE wet strength agent, patent CN202411414459.6 discloses a high-efficiency chlorine-free wet strength agent and a preparation method thereof, which uses tetraethylene pentamine and adipic acid to prepare a polyamide polyamine prepolymer, then adds ethylene glycol diglycidyl ether for reaction, and finally adds epoxy chloropropane to form a modified PAE wet strength agent, which can greatly improve the retention and filtration performance, and greatly improve the paper wet strength, water resistance and folding degree and other paper properties; patent CN202111266850.2 discloses a high-solid-content paper high-efficiency wet strength agent, which comprises a plurality of ethylene polyamine monomers, a dibasic acid, a pH regulator, an epoxy chloropropane, a dechlorination agent, a nano composite material and a multifunctional additive. On the basis of the original polyamide polyamine epoxy chloropropane resin raw material, the solid content of the wet strength agent is improved by the pH regulator, and the nano composite material and the multifunctional additive are used to improve the physical properties of the wet strength agent, thereby prolonging the storage time of the wet strength agent and improving the formaldehyde degradation performance of the wet strength agent.

[0004] However, the existing polyamide epoxy chloropropane resin (PAE) wet strength agent has limited improvement on dry strength (only 15%-20%), and the effect is unstable in complex pulp. SUMMARY

[0005] The present application aims to provide a high-performance paper wet strength agent, which can improve the wet strength and dry strength of paper, and has high mechanical properties and stable chemical properties.

[0006] Another object of the present application is to provide a preparation method of the high-performance paper wet strength agent, which grafts chitosan, long-chain alkyl and layered montmorillonite on a three-dimensional network structure to improve the bonding strength of the wet strength agent and paper fibers and the hydrophobicity of the paper.

[0007] The technical problem of the present application is solved by the following technical scheme.

[0008] In one aspect, the present application provides a high-performance paper wet strength agent, which comprises the following raw materials in parts by weight:

[0009] Triethylenetetramine 60-100 parts, methacryloyloxyethyl trimethyl ammonium chloride 20-30 parts, organically modified montmorillonite 10-20 parts, epoxy resin 5-10 parts, polyamide polyamine 30-50 parts, ethylene glycol methyl ether 10-20 parts, cationic starch 5-10 parts, double-bonded carboxymethyl chitosan 5-10 parts, 1,5-hexadiene diepoxy 1-5 parts, ammonium persulfate 0.1-0.5 parts, and β-cyclodextrin 1-5 parts.

[0010] In some embodiments of the present application, the double-bonded carboxymethyl chitosan is prepared by the following method:

[0011] Chitosan is dispersed in a NaOH solution, and alkali is added at 40-45℃ for 1.5-2 hours; chloroacetic acid is then added, and the reaction is carried out at 60-70℃ for 4-5 hours, and then neutralized to pH=7, and ethanol is added for precipitation and purification to obtain carboxymethyl chitosan.

[0012] The carboxymethyl chitosan is dissolved in a buffer solution with pH 7.0-9.0, and glycidyl methacrylate is then added; the reaction is carried out at 0-5℃ for 2-4 hours to obtain double-bonded carboxymethyl chitosan.

[0013] In some embodiments of the present application, the molar ratio of chitosan to chloroacetic acid is 1:(1-1.2).

[0014] In some embodiments of the present application, the mass-volume ratio of chitosan to NaOH solution is 1g:(5-6)mL, and the mass fraction of the NaOH solution is 40-50%.

[0015] In some embodiments of the present application, the organically modified montmorillonite is prepared by the following method:

[0016] Sodium-based montmorillonite is dispersed in water, and an intercalation agent, cetyltrimethylammonium bromide (CTAB), is then added, and ultrasonic dispersion is carried out for 40-60min; an acrylic monomer is then added, and the pH is adjusted to 6.5-7.5, and ultrasonic dispersion is carried out for another 30-60min; an initiator is then added, and the reaction is carried out at 60-80℃ for 4-6h; after the reaction is completed, the reaction system is cooled to room temperature, and the composite is collected by centrifugation and filtration, and washed with ethanol for 3 times to obtain the organically modified montmorillonite.

[0017] In some embodiments of the present application, the addition amount of the acrylic monomer is 30%-50% of the mass of the sodium-based montmorillonite.

[0018] In some embodiments of the present application, the initiator is ammonium persulfate or potassium persulfate, and the addition amount is 0.5%-1.0% of the mass of the acrylic monomer.

[0019] In some embodiments of the present application, the acrylic monomer is isooctyl acrylate or acrylamide.

[0020] In another aspect, the embodiments of the present application provide a preparation method of a high-performance paper wet strength agent, comprising the following steps:

[0021] S1, adding methacryloyloxyethyl trimethyl ammonium chloride into a saturated solution of β-cyclodextrin, stirring for 1-2 h, then adding triethylenetetramine, organically modified montmorillonite, epoxy resin, ethylene glycol methyl ether, heating to 60-80℃ in water bath and stirring uniformly to obtain a mixed solution A;

[0022] S2, mixing polyamide polyamine, cationic starch and double-bonded carboxymethyl chitosan at 30-40℃

[0023] stirring uniformly to obtain a mixed solution B;

[0024] S3, mixing the mixed solution A, the mixed solution B, 1,5-hexadiene diepoxy and ammonium persulfate uniformly, heating to 60-80℃ in water bath and ultrasonic dispersion for 30-40 min to obtain the paper wet strength agent.

[0025] Compared with the prior art, the embodiments of the present application have at least the following advantages or beneficial effects:

[0026] The paper wet strength agent and the preparation method thereof provided by the present application use triethylenetetramine and polyamide polyamine as the main chain skeleton, form a three-dimensional network structure through epoxy chloropropane crosslinking, significantly improve the molecular weight of the wet strength agent and the fiber bonding force. The double-bonded carboxymethyl chitosan and cationic starch are introduced to enhance the hydrogen bond density between fibers through charge adsorption, and the antibacterial property of chitosan endows the paper with a preservative function. The organically modified montmorillonite forms a nanosheet layer structure through CTAB intercalation and in-situ polymerization of acrylic monomer, effectively prevents the fiber from swelling due to water absorption, and improves the wet strength retention rate by more than 30%. The β-cyclodextrin embedding technology is used to control the slow-release reaction of methacryloyloxyethyl trimethyl ammonium chloride, and reduce the free monomer residue. The 1,5-hexadiene diepoxy is used as a crosslinking agent to form a hydrophobic barrier between fibers, thereby reducing the paper's expansion and deformation rate.

[0027] In summary, the paper wet strength agent provided by the present application has strong bonding force with paper fibers, good dry and wet strength of paper, and stable performance of the wet strength agent. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme of the embodiments of the present application will be described clearly and completely below. If the specific conditions are not specified in the embodiments, the conventional conditions or the conditions recommended by the manufacturer are used. If the reagents or instruments are not specified by the manufacturer, they are all conventional products that can be purchased in the market.

[0029] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in detail below with reference to specific embodiments.

[0030] In one aspect, the present application provides a high-performance paper wet strength agent, comprising the following raw materials in parts by weight:

[0031] 60-100 parts of triethylenetetramine, 20-30 parts of methacryloyloxyethyl trimethyl ammonium chloride, 10-20 parts of organically modified montmorillonite, 5-10 parts of epoxy resin, 30-50 parts of polyamide polyamine, 10-20 parts of ethylene glycol methyl ether, 5-10 parts of cationic starch, 5-10 parts of double-bonded carboxymethyl chitosan, 1-5 parts of 1,5-hexadiene diepoxy, 0.1-0.5 parts of ammonium persulfate, and 1-5 parts of β-cyclodextrin. The acrylic monomer is isooctyl acrylate or acrylamide. The cationic starch is quaternary ammonium type cationic starch (3-chloro-2-hydroxypropyl trimethyl ammonium chloride modified starch) or tertiary amine type cationic starch (2,3-epoxypropyl trimethyl ammonium chloride modified starch).

[0032] The double-bonded carboxymethyl chitosan is prepared by the following method:

[0033] Disperse chitosan in NaOH solution, alkalinize at 40-45℃ for 1.5-2 hours, then add chloroacetic acid, react at 60-70℃ for 4-5 hours, neutralize to pH=7, precipitate and purify with ethanol to obtain carboxymethyl chitosan;

[0034] Dissolve the carboxymethyl chitosan in a buffer solution (pH 7.0-9.0), then add glycidyl methacrylate; react at 0-5℃, and the reaction time is 2-4 hours to obtain double-bonded carboxymethyl chitosan. The molar ratio of chitosan to chloroacetic acid is 1:(1-1.2). The mass-volume ratio of chitosan to NaOH solution is 1g:(5-6)mL, and the mass fraction of NaOH solution is 40-50%.

[0035] The organically modified montmorillonite is prepared by the following method:

[0036] The sodium-based montmorillonite is dispersed in water, then an intercalation agent (cetyltrimethylammonium bromide CTAB) is added, and ultrasonic dispersion is performed for 40-60 min; then acrylic monomers are added, the pH is adjusted to 6.5-7.5, and ultrasonic dispersion is performed for 30-60 min; an initiator is added, and reaction is performed at 60-80°C for 4-6 h; after the reaction is completed, the temperature is cooled to room temperature; the composite is collected by centrifugation and filtration, and washed with ethanol for 3 times, to obtain the organic modified montmorillonite. The acrylic monomers are added in an amount of 30%-50% of the mass of the sodium-based montmorillonite. The initiator is ammonium persulfate or potassium persulfate, and is added in an amount of 0.5%-1.0% of the mass of the acrylic monomers.

[0037] The embodiment of the present application provides a preparation method of a high-performance paper wet strength agent, comprising the following steps:

[0038] S1, methyl methacryloyloxyethyl trimethyl ammonium chloride is added to a saturated β-cyclodextrin solution, stirred for 1-2 h, then triethylenetetramine, organic modified montmorillonite, epoxy resin, and ethylene glycol methyl ether are added, and the mixture is uniformly heated to 60-80°C in a water bath and stirred, to obtain a mixed solution A;

[0039] S2, polyamide polyamine, cationic starch, and double-bonded carboxymethyl chitosan are mixed and uniformly stirred at 30-40°C, to obtain a mixed solution B;

[0040] S3, the mixed solution A, the mixed solution B, 1,5-hexadiene diepoxy, and ammonium persulfate are uniformly mixed, heated to 60-80°C in a water bath, and ultrasonically dispersed for 30-40 min, to obtain the paper wet strength agent.

[0041] The features and performances of the present application are further described in detail in combination with the following embodiments.

[0042] Embodiment 1

[0043] The paper wet strength agent of the present embodiment is prepared according to the following proportioning and method:

[0044] Triethylenetetramine 100 parts, methyl methacryloyloxyethyl trimethyl ammonium chloride 30 parts, organic modified montmorillonite 20 parts, epoxy resin (epoxy resin E20) 10 parts, polyamide polyamine (BASF series) 50 parts, ethylene glycol methyl ether 20 parts, cationic starch 10 parts, double-bonded carboxymethyl chitosan 10 parts, 1,5-hexadiene diepoxy 5 parts, and ammonium persulfate 0.5 parts, and β-cyclodextrin 5 parts.

[0045] The acrylic monomers are isooctyl acrylate; and the cationic starch is quaternary ammonium type cationic starch (3-chloro-2-hydroxypropyl trimethyl ammonium chloride modified starch).

[0046] In this embodiment, the double-bonded carboxymethyl chitosan is prepared by the following method:

[0047] Chitosan was dispersed in a 50% NaOH solution at a mass-volume ratio of 1g:6mL and alkalized at 40℃ for 2 hours. Then, chloroacetic acid was added, with a molar ratio of chitosan to chloroacetic acid of 1:1.2, and the mixture was reacted at 70℃ for 4 hours. The mixture was then neutralized to pH=7 and purified by ethanol precipitation to obtain carboxymethyl chitosan.

[0048] The carboxymethyl chitosan was dissolved in a buffer solution (pH 7.0–9.0), and then glycidyl methacrylate was added. The reaction was carried out at a low temperature of 0–5°C for 4 hours to obtain double-bonded carboxymethyl chitosan. The molar ratio of chitosan to glycidyl methacrylate was 1:1.2.

[0049] The organically modified montmorillonite in this embodiment was prepared by the following method:

[0050] Sodium-based montmorillonite was dispersed in water, and then an intercalating agent (hexadecyltrimethylammonium bromide CTAB) was added. The mixture was ultrasonically dispersed for 60 min. Then, isooctyl acrylate monomer was added at an amount of 30% of the mass of sodium-based montmorillonite. The pH was adjusted to 6.5–7.5, and the mixture was ultrasonically dispersed for another 60 min. Ammonium persulfate initiator was added at an amount of 0.5% of the isooctyl acrylate monomer. The mixture was reacted at 60 °C for 6 h. After the reaction was completed, the mixture was cooled to room temperature. The complex was collected by centrifugation and filtration, and washed three times with ethanol to obtain the organically modified montmorillonite.

[0051] The paper wet strength agent in this embodiment is prepared by the following method:

[0052] S1, add methacryloyloxyethyltrimethylammonium chloride to a saturated β-cyclodextrin solution, stir for 1 hour, then add triethylenetetramine, organic modified montmorillonite, epoxy resin, and ethylene glycol methyl ether, heat in a water bath to 80°C and stir until homogeneous to obtain mixture A;

[0053] S2, mix polyamide polyamine, cationic starch and double-bonded carboxymethyl chitosan, and stir evenly at 30°C to obtain mixture B;

[0054] S3. Mix mixture A, mixture B, 1,5-hexadiene diepoxide, and ammonium persulfate evenly, heat in a water bath to 80°C, and ultrasonically disperse for 40 minutes to obtain the paper wet strength agent.

[0055] Example 2

[0056] The paper wet strength agent of this embodiment was prepared according to the following proportions and method:

[0057] 100 parts triethylenetetramine, 20 parts methacryloyloxyethyltrimethylammonium chloride, 10 parts organically modified montmorillonite, 10 parts epoxy resin (epoxy resin E20), and polyamide polyamine (BASF). 30 parts of the series, 10 parts of ethylene glycol methyl ether, 5 parts of cationic starch, 5 parts of double-bonded carboxymethyl chitosan, 5 parts of 1,5-hexadiene diepoxide, 0.1 parts of ammonium persulfate, and 1 part of β-cyclodextrin.

[0058] Among them, the acrylic monomer is isooctyl acrylate; the cationic starch is quaternary ammonium cationic starch (3-chloro-2-hydroxypropyltrimethylammonium chloride modified starch).

[0059] In this embodiment, the double-bonded carboxymethyl chitosan is the same as that in Example 1; the organically modified montmorillonite is also the same as that in Example 1.

[0060] The preparation method of the paper wet strength agent in this embodiment is the same as that in Example 1.

[0061] Example 3

[0062] The paper wet strength agent of this embodiment was prepared according to the following proportions and method:

[0063] 60 parts triethylenetetramine, 20 parts methacryloyloxyethyltrimethylammonium chloride, 10 parts organically modified montmorillonite, 5 parts epoxy resin (epoxy resin E20), and polyamide polyamine (BASF). 30 parts of the series, 10 parts of ethylene glycol methyl ether, 5 parts of cationic starch, 5 parts of double-bonded carboxymethyl chitosan, 1 part of 1,5-hexadiene diepoxide, 0.1 parts of ammonium persulfate, and 1 part of β-cyclodextrin.

[0064] Among them, the acrylic monomer is isooctyl acrylate; the cationic starch is quaternary ammonium cationic starch (3-chloro-2-hydroxypropyltrimethylammonium chloride modified starch).

[0065] In this embodiment, the double-bonded carboxymethyl chitosan is the same as that in Example 1; the organically modified montmorillonite is also the same as that in Example 1.

[0066] The preparation method of the paper wet strength agent in this embodiment is the same as that in Example 1.

[0067] Example 4

[0068] The difference from Example 1 is that the double-bonded carboxymethyl chitosan in this example is prepared by the following method:

[0069] Chitosan was dispersed in a 40% NaOH solution at a mass-volume ratio of 1g:5mL and alkalized at 40℃ for 2 hours. Then, chloroacetic acid was added, with a molar ratio of chitosan to chloroacetic acid of 1:1. The mixture was reacted at 70℃ for 4 hours, neutralized to pH=7, and purified by ethanol precipitation to obtain carboxymethyl chitosan.

[0070] The carboxymethyl chitosan was dissolved in a buffer solution (pH 7.0–9.0), and then glycidyl methacrylate was added. The reaction was carried out at a low temperature of 0–5°C for 4 hours to obtain double-bonded carboxymethyl chitosan. The molar ratio of chitosan to glycidyl methacrylate was 1:1.2.

[0071] The remaining raw material ratios and preparation methods are the same as those in Example 1.

[0072] Example 5

[0073] The difference from Example 1 is that the organically modified montmorillonite in this example is prepared by the following method:

[0074] Sodium montmorillonite was dispersed in water, and an intercalating agent (hexadecyltrimethylammonium bromide CTAB) was added. The mixture was ultrasonically dispersed for 60 min. Acrylamide monomer was then added at 30% of the mass of sodium montmorillonite. The pH was adjusted to 6.5–7.5, and the mixture was ultrasonically dispersed for another 60 min. Ammonium persulfate was added as an initiator at 1.0% of the acrylamide monomer. The mixture was reacted at 60 °C for 6 h. After the reaction was completed, the mixture was cooled to room temperature. The complex was collected by centrifugation and filtration, and washed three times with ethanol to obtain the organically modified montmorillonite.

[0075] Example 6

[0076] The difference from Example 1 is that the paper wet strength agent is prepared in this example according to the following method:

[0077] S1, add methacryloyloxyethyltrimethylammonium chloride to a saturated β-cyclodextrin solution, stir for 1 hour, then add triethylenetetramine, organic modified montmorillonite, epoxy resin, and ethylene glycol methyl ether, heat in a water bath to 60°C and stir until homogeneous to obtain mixture A;

[0078] S2, mix polyamide polyamine, cationic starch and double-bonded carboxymethyl chitosan, and stir evenly at 35°C to obtain mixture B;

[0079] S3. Mix mixture A, mixture B, 1,5-hexadiene diepoxide, and ammonium persulfate evenly, heat in a water bath to 60°C, and ultrasonically disperse for 40 minutes to obtain the paper wet strength agent.

[0080] The proportions of the remaining raw materials are the same as in Example 1.

[0081] Comparative Example 1

[0082] The difference from Example 1 is that no organically modified montmorillonite is added to the raw materials, while the other raw material ratios and preparation methods are the same as in Example 1.

[0083] Comparative Example 2

[0084] The difference from Example 1 is that cationic starch is not added to the raw materials, while the other raw material ratios and preparation methods are the same as in Example 1.

[0085] Comparative Example 3

[0086] The difference from Example 1 is that double-bonded carboxymethyl chitosan is not added to the raw materials, while the other raw material ratios and preparation methods are the same as in Example 1.

[0087] Comparative Example 4

[0088] The difference from Example 1 is that no organically modified montmorillonite and double-bonded carboxymethyl chitosan are added to the raw materials, while the remaining raw material ratios and preparation methods are the same as in Example 1.

[0089] Experimental Example

[0090] Paper preparation: The pulp used is bamboo fiber pulp with a beating degree of 45°SR.

[0091] The wet strength agent products of Examples 1-6 and Comparative Examples 1-4 were diluted to a solid content of 1%, with a target basis weight of 100 g / m² for paper. 2 The prepared paper sheets are dried in an oven at 105℃ for 15 minutes, then removed and cooled to room temperature before use. This is used to test the dry strength index of the paper.

[0092] Paper was cut into 15mm × 150mm pieces, soaked in water for 10 minutes, and then removed to remove excess surface moisture. These pieces were used as wet strength index test specimens. The specimens were then quickly placed on a tensile strength testing machine to determine their tensile index. The results are shown in Table 1.

[0093] Table 1

[0094]

[0095]

[0096] Table 1 shows that the wet strength agents provided in Examples 1-6, when used in bamboo fiber pulp, significantly improve the wet and dry tensile strength of the paper, resulting in excellent mechanical properties. In Comparative Example 1, the wet strength agent did not contain organically modified montmorillonite, leading to poor water barrier properties on the paper surface and significantly lower wet tensile strength compared to Examples 1-6. In Comparative Example 2, the absence of cationic starch resulted in insufficient bonding between the wet strength agent and the paper fibers, also affecting the tensile strength of the paper to some extent.

[0097] In summary, the paper wet strength agent and its preparation method provided in this invention can simultaneously improve both wet and dry tensile strength of paper. It uses a compound of triethylenetetramine and polyamide polyamine as the main chain backbone, forming a three-dimensional network structure through epichlorohydrin crosslinking, significantly increasing the molecular weight of the wet strength agent and its binding force to fibers. The introduction of double-bonded carboxymethyl chitosan and cationic starch enhances the hydrogen bond density between fibers through charge adsorption, while the antibacterial properties of chitosan impart anti-corrosion function to the paper. Organically modified montmorillonite, through CTAB intercalation and in-situ polymerization of acrylic monomers, forms a nanosheet structure, effectively preventing fiber water absorption and swelling, increasing the wet strength retention rate by more than 30%. The use of β-cyclodextrin encapsulation technology controls the slow-release reaction of methacryloyloxyethyltrimethylammonium chloride, reducing free monomer residue. 1,5-hexadiene diepoxide, as a crosslinking agent, can form a hydrophobic barrier between fibers, reducing the paper's stretching and deformation rate.

[0098] The embodiments described above are some, but not all, embodiments of the present invention. The detailed description of the embodiments of the present invention is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

Claims

1. A high-performance paper wet strength agent, characterized in that, By weight, it includes the following ingredients: Triethylenetetramine 60-100 parts, methacryloyloxyethyltrimethylammonium chloride 20-30 parts, organically modified montmorillonite 10-20 parts, epoxy resin 5-10 parts, polyamide polyamine 30-50 parts, ethylene glycol methyl ether 10-20 parts, cationic starch 5-10 parts, double-bonded carboxymethyl chitosan 5-10 parts, 1,5-hexadiene diepoxide 1-5 parts, ammonium persulfate 0.1-0.5 parts, β-cyclodextrin 1-5 parts.

2. The high-performance paper wet strength agent according to claim 1, characterized in that, The double-bonded carboxymethyl chitosan was prepared by the following method: Chitosan was dispersed in NaOH solution and alkalized at 40-45℃ for 1.5-2 hours; then chloroacetic acid was added and reacted at 60-70℃ for 4-5 hours. The mixture was neutralized to pH=7 and purified by ethanol precipitation to obtain carboxymethyl chitosan. The carboxymethyl chitosan was dissolved in a buffer solution at pH 7.0–9.0, and then glycidyl methacrylate was added. The mixture was reacted at a low temperature of 0–5°C for 2–4 hours to obtain double-bonded carboxymethyl chitosan.

3. The high-performance paper wet strength agent according to claim 2, characterized in that, The molar ratio of chitosan to chloroacetic acid is 1:(1-1.2).

4. The high-performance paper wet strength agent according to claim 1, characterized in that, The mass-to-volume ratio of chitosan to NaOH solution is 1 g:(5-6) mL, and the mass fraction of NaOH solution is 40-50%.

5. The high-performance paper wet strength agent according to claim 1, characterized in that, The organically modified montmorillonite was prepared by the following method: Sodium-based montmorillonite was dispersed in water, and then the intercalating agent hexadecyltrimethylammonium bromide was added. The mixture was ultrasonically dispersed for 40-60 min. Then, an acrylic monomer was added, the pH was adjusted to 6.5-7.5, and the mixture was ultrasonically dispersed for another 30-60 min. An initiator was added, and the mixture was reacted at 60-80℃ for 4-6 h. After the reaction was completed, the mixture was cooled to room temperature, and the complex was collected by centrifugation and filtration. The complex was washed three times with ethanol to obtain the organically modified montmorillonite.

6. The high-performance paper wet strength agent according to claim 5, characterized in that, The amount of acrylic monomer added is 30%–50% of the mass of sodium montmorillonite.

7. The high-performance paper wet strength agent according to claim 5, characterized in that, The initiator is ammonium persulfate or potassium persulfate, and its addition amount is 0.5%–1.0% of the mass of the acrylic monomer.

8. The high-performance paper wet strength agent according to claim 5, characterized in that, The acrylic monomer is isooctyl acrylate or acrylamide.

9. A method for preparing a high-performance paper wet strength agent as described in any one of claims 1-8, characterized in that, Includes the following steps: S1, add methacryloyloxyethyltrimethylammonium chloride to a saturated β-cyclodextrin solution, stir for 1-2 hours, then add triethylenetetramine, organically modified montmorillonite, epoxy resin, and ethylene glycol methyl ether, heat in a water bath to 60-80℃ and stir until homogeneous to obtain mixture A; S2, mix polyamide polyamine, cationic starch and double-bonded carboxymethyl chitosan, and stir evenly at 30-40℃ to obtain mixture B; S3. Mix mixture A, mixture B, 1,5-hexadiene diepoxide, and ammonium persulfate evenly, heat in a water bath to 60-80℃, and ultrasonically disperse for 30-40 minutes to obtain the paper wet strength agent.

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