A high solid content wet strength agent and a method for preparing the same

Abstract

The application relates to the technical field of paper wet strength agent, and discloses a high-solid-content wet strength agent and a preparation method thereof. The preparation method comprises the following steps: reacting a dibasic acid and a dibasic amine under the action of an acid catalyst to obtain a polyamide prepolymer; after the polyamide prepolymer is cooled, deionized water is added to adjust the solid content, then allyl glycidyl ether, limonene, organic modified montmorillonite and an initiator are added, and a polyamide intermediate is obtained through reaction; the polyamide intermediate is cooled to room temperature, and epichlorohydrin is added dropwise, and after reaction at room temperature, the temperature is increased for reaction, and the solid content is adjusted, and the high-solid-content wet strength agent is obtained. After the limonene in the wet strength agent is grafted, hydrophobic microzones are formed in the polymer network, the combination and penetration capacity of water molecules, paper fibers and the wet strength agent can be reduced, the wet resistance and wet strength of paper can be improved, and the organic modified montmorillonite can form synergy with the hydrophobic microzones constructed by the limonene, so that the wet strength and wet resistance of the wet strength agent are further improved.

Description

Technical Field

[0001] This invention relates to the field of paper wet strength agent technology, and in particular to a high solids content wet strength agent and its preparation method. Background Technology

[0002] Polyamide epichlorohydrin (PAE) resin is a thermosetting resin and currently the most widely used cationic reactive wet strength agent in the papermaking industry. It is synthesized from polyamide polyamines and epichlorohydrin (ECH) as core raw materials through reactions such as polycondensation and epoxidation. As a wet strength agent, it is added to the pulp during the papermaking process, imparting excellent wet strength properties to the paper after molding and drying. Due to its efficient wet strength imparting ability, good papermaking compatibility, and cost-effectiveness, polyamide epichlorohydrin resin has become the mainstream choice for improving the wet mechanical properties of various types of paper, and is widely used in products with special requirements for wet strength, such as toilet paper, diapers, map paper, and paper bags.

[0003] However, PAE molecules contain highly reactive groups; the higher the solid content, the worse the system stability, making it prone to gelation and loss of flowability. This results in generally low solid content in PAE resins produced using existing technologies, leading to high transportation costs. Furthermore, during the production of PAE-type wet-strength agents, epichlorohydrin is prone to hydrolysis, generating toxic chlorine-containing organic byproducts such as 1,3-dichloro-2-propanol and 3-chloro-1,2-propanediol, posing potential health risks. Therefore, increasing the solid content of PAE resin, reducing residual organic chlorine, and enhancing its wet-strength properties are crucial for reducing transportation costs, improving paper quality, and enhancing market competitiveness. Summary of the Invention

[0004] In order to overcome the shortcomings of the prior art, one of the objectives of the present invention is to provide a high solids content moisture strength agent.

[0005] The second objective of this invention is to provide a method for preparing a high-solids-content wet strength agent.

[0006] To achieve the above objectives, the present invention employs the following technical solution: This invention provides a method for preparing a high-solids-content wet strength agent, comprising the following steps: (1) A dicarboxylic acid and a diamine are reacted at 120-170℃ for 8-12h under the action of an acidic catalyst to obtain a polyamide prepolymer; (2) Cool the polyamide prepolymer obtained in step (1) to 30-60°C, add deionized water to adjust the solid content to 30-50%, and then add allyl glycidyl ether, limonene, organic modified montmorillonite and initiator. After reacting at 50-80°C for 1-3 hours, the polyamide intermediate is obtained. (3) Cool the polyamide intermediate obtained in step (2) to room temperature, add epichlorohydrin dropwise, react at room temperature for 30-90 min, then heat to 50-60℃ and react for 1-4 h, adjust the pH to 3-5, add water to adjust the solid content to 35-45%, and you will get the product.

[0007] Preferably, the preparation process of the organically modified montmorillonite in step (2) is as follows: (2-1) Montmorillonite was ultrasonically dispersed in an aqueous ethanol solution, diethylaminomethyltriethoxysilane was added, the pH was adjusted to 4-5, and the reaction was carried out at 50-60℃ for 1-2 hours. After filtration, washing, and vacuum drying, amination montmorillonite was obtained. (2-2) Amine-modified montmorillonite was ultrasonically dispersed in acetonitrile, 1-azido-3-bromopropane was added, and the mixture was reacted at 60-70℃ for 24-36 h. After filtration, washing, and vacuum drying, montmorillonite azido-modified was obtained. (2-3) Azide-modified montmorillonite was ultrasonically dispersed in methanol, and 1-penten-4-yn-3 alcohol, copper sulfate solution and sodium ascorbate solution were added. Under nitrogen protection, the mixture was reacted at 40-50℃ for 15-20 h, filtered, washed and vacuum dried to obtain organically modified montmorillonite.

[0008] Preferably, in step (2-1), the ratio of montmorillonite, diethylaminomethyltriethoxysilane and ethanol aqueous solution is 1g:0.6-0.8g:20-30mL; the ethanol aqueous solution is a mixture of ethanol and deionized water in a volume ratio of 1:(2-3).

[0009] Preferably, in step (2-2), the ratio of aminated montmorillonite, 1-azido-3-bromopropane and acetonitrile is 1g:0.5-0.9g:20-30mL.

[0010] Preferably, in step (2-3), the amounts of montmorillonite azide, 1-penten-4-yn-3 alcohol, copper sulfate solution, sodium ascorbate solution, and methanol are 1g:0.3-0.5g:2-3mL:1-1.5mL:20-30mL; the concentration of copper sulfate solution is 0.1M; and the concentration of sodium ascorbate solution is 1M.

[0011] Preferably, in step (1), the molar ratio of dicarboxylic acid, diamine, and acidic catalyst is 1:(0.85-0.95):(0.02-0.03); the dicarboxylic acid is adipic acid and fumaric acid, and the mass ratio of adipic acid to fumaric acid is (5-8):1.

[0012] Preferably, in step (2), the mass ratio of allyl glycidyl ether, limonene, organically modified montmorillonite and initiator is 1:(0.36-0.6):(0.2-0.4):(0.001-0.005); the amount of allyl glycidyl ether is 0.05-0.1 times the molar amount of the dicarboxylic acid.

[0013] Preferably, in step (3), the amount of epichlorohydrin used is 0.2-0.5 times the molar amount of the dicarboxylic acid.

[0014] Preferably, in step (1), the acidic catalyst is p-toluenesulfonic acid or dodecylbenzenesulfonic acid; the diamine is any one or more of diethylenetriamine, triethylenetetramine, or tetraethylenepentamine; and in step (2), the initiator is any one or more of ammonium persulfate, sodium persulfate, or azobisisobutyronitrile.

[0015] This invention provides a high solids content moisture-strength agent, which is prepared according to the preparation method described above.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention provides a high-solids-content wet-strength agent. First, a polyamide prepolymer containing carbon-carbon double bonds is synthesized via a condensation reaction of a diamine and a diacid (containing unsaturated fumaric acid). Then, the double bonds of this prepolymer are used to undergo free radical polymerization with organically modified montmorillonite, limonene, and allyl glycidyl ether to form a multi-branched polymer network. Finally, the agent is cross-linked with epichlorohydrin and quaternized to obtain the high-solids-content wet-strength agent. Detailed analysis is as follows: (1) In this invention, limonene participates in the free radical copolymerization reaction during the preparation of wet strength agent through double bonds in its molecule, and is covalently grafted onto the polyamide prepolymer backbone. After grafting, the cyclic hydrophobic hydrocarbon groups of limonene form hydrophobic microdomains in the polymer network, reducing the binding and penetration ability of water molecules with paper fibers and wet strength agent, reducing the damage of hydrogen bonds between fibers by water molecules, and helping to improve the wet resistance and wet strength of paper. In addition, its steric hindrance directly hinders the physical entanglement between molecular chains and the contact of active groups, and inhibits the side reactions between chains from the kinetic level by reducing the flexibility of the main chain; at the same time, its hydrophobicity causes the molecular chains to adopt a more compact "inward contraction" conformation. The synergy of the two can effectively avoid the gelation caused by excessive cross-linking or molecular aggregation of wet strength agent during reaction and storage and transportation, so that the system can maintain a stable flow state at high solid content, thereby reducing transportation and storage costs.

[0017] (2) The organically modified montmorillonite of this invention is modified in three steps: silane coupling, quaternization, and click chemistry, introducing quaternary ammonium cations, terminal alkenyl groups, hydroxyl groups, and triazole rings into the interlayer of montmorillonite. Among them, the quaternary ammonium cations can significantly increase the cationic charge density of the system, which can not only greatly enhance the retention rate of wet strength agents, but also reduce the system's dependence on epichlorohydrin, thereby reducing the generation of organochlorine byproducts from the source; the terminal alkenyl groups participate in the free radical copolymerization reaction to achieve chemical bonding and anchoring between montmorillonite and polyamide prepolymers. The nano-reinforcing effect and physical barrier effect brought by montmorillonite can synergize with the hydrophobic microdomains constructed by limonene, effectively improving the wet strength and moisture resistance of the wet strength agent; the triazole ring and hydroxyl groups can provide additional hydrogen bonding sites and reactive sites, synergistically enhancing the crosslinking density of the polymer network. Attached Figure Description

[0018] Figure 1 This is a scanning electron microscope image of the organically modified montmorillonite obtained in Example 1 of the present invention. Detailed Implementation

[0019] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments. Specific conditions not specified in the embodiments shall be performed according to conventional conditions or conditions recommended by the manufacturer. Unless otherwise specified, all reagents or instruments used are conventional products obtained through commercial channels. Example 1

[0020] This embodiment provides a method for preparing a high solids content wet strength agent, including the following steps: (1) A dicarboxylic acid (the mass ratio of adipic acid to fumaric acid is 7:1) and a diamine (diethylenetriamine) are reacted at 150°C for 10 h under the action of an acidic catalyst (p-toluenesulfonic acid), wherein the molar ratio of dicarboxylic acid, diamine and acidic catalyst is 1:0.9:0.025, to obtain a polyamide prepolymer; (2) Cool the polyamide prepolymer obtained in step (1) to 50°C, add deionized water to adjust the solid content to 50%, add allyl glycidyl ether, limonene, organic modified montmorillonite and initiator (ammonium persulfate), wherein the mass ratio of allyl glycidyl ether, limonene, organic modified montmorillonite and initiator is 1:0.5:0.3:0.004; the amount of allyl glycidyl ether is 0.07 times the molar amount of diacid; after reacting at 70°C for 2 hours, a polyamide intermediate is obtained; (3) Cool the polyamide intermediate obtained in step (2) to room temperature, add epichlorohydrin dropwise, wherein the amount of epichlorohydrin is 0.2 times the molar amount of the diacid; react at room temperature for 60 min, then heat to 55℃ and react for 3 h, then adjust the pH to 4 with organic acid (citric acid) to terminate the reaction, add water to adjust the solid content to 45%, and the high solid content moisture strength agent is obtained.

[0021] The preparation process of the organically modified montmorillonite in this embodiment is as follows: (2-1) Montmorillonite was ultrasonically dispersed in an ethanol-water solution (volume ratio of ethanol to deionized water was 1:2), and diethylaminomethyltriethoxysilane was added. The volume ratio of montmorillonite, diethylaminomethyltriethoxysilane and ethanol-water solution was 1 g: 0.7 g: 25 mL. The pH of the system was adjusted to 5 with glacial acetic acid. After reacting at 55 °C for 1.5 h, the mixture was filtered, washed with ethanol, and dried under vacuum to obtain amination-modified montmorillonite. (2-2) Amine montmorillonite was ultrasonically dispersed in acetonitrile, and 1-azido-3-bromopropane was added, wherein the ratio of amine montmorillonite, 1-azido-3-bromopropane and acetonitrile was 1 g: 0.7 g: 25 mL; after reacting at 65 °C for 32 h, the mixture was filtered, washed with acetonitrile, and dried under vacuum to obtain amine montmorillonite; (2-3) Azide-modified montmorillonite was ultrasonically dispersed in methanol, and 1-penten-4-yn-3-ol, copper sulfate solution (0.1M), and sodium ascorbate solution (1M) were added. The amounts of montmorillonite azide, 1-penten-4-yn-3-ol, copper sulfate solution, sodium ascorbate solution, and methanol were 1 g: 0.4 g: 2.5 mL: 1.5 mL: 25 mL. The mixture was reacted at 45 °C for 18 h under nitrogen protection, filtered, washed with ethanol and deionized water, and vacuum dried to obtain organically modified montmorillonite. The scanning electron microscope image of the obtained organically modified montmorillonite is shown below. Figure 1 As shown.

[0022] This embodiment provides a high solids content moisture-strength agent, which is prepared according to the preparation method described above. Example 2

[0023] This embodiment provides a method for preparing a high solids content wet strength agent, including the following steps: (1) A dicarboxylic acid (the mass ratio of adipic acid to fumaric acid is 8:1) and a diamine (tetraethylenepentamine) were reacted at 170°C for 8 hours under the action of an acidic catalyst (dodecylbenzenesulfonic acid), wherein the molar ratio of the dicarboxylic acid, the diamine and the acidic catalyst was 1:0.95:0.03, to obtain a polyamide prepolymer; (2) Cool the polyamide prepolymer obtained in step (1) to 60°C, add deionized water to adjust the solid content to 40%, and add allyl glycidyl ether, limonene, organic modified montmorillonite and initiator (sodium persulfate). The mass ratio of allyl glycidyl ether, limonene, organic modified montmorillonite and initiator is 1:0.6:0.4:0.005. The amount of allyl glycidyl ether is 0.1 times the molar amount of diacid. After reacting at 80°C for 1 h, a polyamide intermediate is obtained. (3) Cool the polyamide intermediate obtained in step (2) to room temperature, add epichlorohydrin dropwise, wherein the amount of epichlorohydrin is 0.3 times the molar amount of the diacid; react at room temperature for 90 min, then heat to 60℃ and react for 1 h, then adjust the pH to 5 with organic acid (citric acid) to terminate the reaction, add water to adjust the solid content to 40%, and the high solid content moisture strength agent is obtained.

[0024] The preparation process of the organically modified montmorillonite in this embodiment is as follows: (2-1) Montmorillonite was ultrasonically dispersed in an ethanol-water solution (ethanol to deionized water volume ratio of 1:3), and diethylaminomethyltriethoxysilane was added, wherein the volume ratio of montmorillonite, diethylaminomethyltriethoxysilane and ethanol-water solution was 1 g: 0.8 g: 30 mL; the pH of the system was adjusted to 5 with glacial acetic acid, and the reaction was carried out at 60 °C for 1 h. After filtration, washing with ethanol, and vacuum drying, amination montmorillonite was obtained. (2-2) Amine montmorillonite was ultrasonically dispersed in acetonitrile, and 1-azido-3-bromopropane was added, wherein the ratio of amine montmorillonite, 1-azido-3-bromopropane and acetonitrile was 1 g: 0.9 g: 30 mL; after reacting at 70 °C for 24 h, the mixture was filtered, washed with acetonitrile, and dried under vacuum to obtain amine montmorillonite; (2-3) Azide-modified montmorillonite was ultrasonically dispersed in methanol, and 1-penten-4-yn-3 alcohol, copper sulfate solution (0.1M) and sodium ascorbate solution (1M) were added. The amounts of azide-modified montmorillonite, 1-penten-4-yn-3 alcohol, copper sulfate solution, sodium ascorbate solution and methanol were 1g:0.5g:3mL:1.5mL:30mL. After reacting at 50℃ for 15h under nitrogen protection, the mixture was filtered, washed with ethanol and deionized water, and dried under vacuum to obtain organically modified montmorillonite.

[0025] This embodiment provides a high solids content moisture-strength agent, which is prepared according to the preparation method described above. Example 3

[0026] This embodiment provides a method for preparing a high solids content wet strength agent, including the following steps: (1) A dicarboxylic acid (the mass ratio of adipic acid to fumaric acid is 5:1) and a diamine (triethylenetetramine) are reacted at 120°C for 12 h under the action of an acidic catalyst (p-toluenesulfonic acid), wherein the molar ratio of dicarboxylic acid, diamine and acidic catalyst is 1:0.85:0.02, to obtain a polyamide prepolymer; (2) Cool the polyamide prepolymer obtained in step (1) to 30°C, add deionized water to adjust the solid content to 30%, and add allyl glycidyl ether, limonene, organic modified montmorillonite and initiator (azobisisobutyronitrile). The mass ratio of allyl glycidyl ether, limonene, organic modified montmorillonite and initiator is 1:0.36:0.2:0.001. The amount of allyl glycidyl ether is 0.05 times the molar amount of diacid. After reacting at 50°C for 3 hours, a polyamide intermediate is obtained. (3) Cool the polyamide intermediate obtained in step (2) to room temperature, add epichlorohydrin dropwise, wherein the amount of epichlorohydrin is 0.5 times the molar amount of the diacid; react at room temperature for 30 min, then heat to 50℃ and react for 4 h, then use organic acid (citric acid) to adjust the pH to 3 to terminate the reaction, add water to adjust the solid content to 35%, and the high solid content moisture strength agent is obtained.

[0027] The preparation process of the organically modified montmorillonite in this embodiment is as follows: (2-1) Montmorillonite was ultrasonically dispersed in an ethanol-water solution (volume ratio of ethanol to deionized water was 1:2), and diethylaminomethyltriethoxysilane was added. The volume ratio of montmorillonite, diethylaminomethyltriethoxysilane and ethanol-water solution was 1 g: 0.6 g: 20 mL. The pH of the system was adjusted to 4 with glacial acetic acid. After reacting at 50 °C for 2 h, the mixture was filtered, washed with ethanol, and dried under vacuum to obtain amination-modified montmorillonite. (2-2) Amine montmorillonite was ultrasonically dispersed in acetonitrile, and 1-azido-3-bromopropane was added, wherein the ratio of amine montmorillonite, 1-azido-3-bromopropane and acetonitrile was 1 g: 0.5 g: 20 mL; after reacting at 60 °C for 36 h, the mixture was filtered, washed with acetonitrile, and dried under vacuum to obtain amine montmorillonite; (2-3) Azide-modified montmorillonite was ultrasonically dispersed in methanol, and 1-penten-4-yn-3 alcohol, copper sulfate solution (0.1M) and sodium ascorbate solution (1M) were added. The amounts of azide-modified montmorillonite, 1-penten-4-yn-3 alcohol, copper sulfate solution, sodium ascorbate solution and methanol were 1g:0.3g:2mL:1mL:20mL. After reacting at 40℃ for 20h under nitrogen protection, the mixture was filtered, washed with ethanol and deionized water, and dried under vacuum to obtain organically modified montmorillonite.

[0028] This embodiment provides a high solids content moisture-strength agent, which is prepared according to the preparation method described above.

[0029] Comparative Example 1 The difference between this comparative example and Example 1 is that the organic modified montmorillonite in step (2) is replaced with montmorillonite, while the rest is the same as in Example 1.

[0030] Comparative Example 2 The difference between this comparative example and Example 1 is that limonene in step (2) is omitted, while the rest remains the same as in Example 1.

[0031] Experimental Example 1 The contents of organochlorohydrins DCP (1,3-dichloro-2-propanol) and MCPD (3-chloro-1,2-propanediol) in the wet strength agents prepared in Examples 1-3 were determined. The results are shown in Table 1.

[0032]

[0033] As shown in Table 1, the content of organochlorohydrins in the wet strength agents obtained in Examples 1-3 of the present invention is extremely low (all below 100 ppm). This is because the introduction of organically modified montmorillonite in the wet strength agents of the present invention can reduce the system's dependence on epichlorohydrin and reduce the generation of organochlorine byproducts from the source.

[0034] Experimental Example 2 Hardwood pulp and softwood pulp were mixed and beaten at a mass ratio of 4:1, achieving a freeness of 38°SR. Wet strength agents prepared in Examples 1-3 and Comparative Examples 1-2 were added, with an addition amount of 0.3% (wet strength agent oven-dry weight / pulp oven-dry weight). The paper basis weight was 80 g / m³. 2 Hand-made sheets were prepared for each experimental group, and a blank sample was prepared without the addition of wet strength agent. The tensile strength, water absorption value and other properties were measured as follows. (1) The dry tensile index and wet tensile index were tested according to GB / T12914-2008 "Determination of tensile strength of paper and paperboard" and GB / T465.2-2008 "Determination of tensile strength of paper and paperboard after immersion in water", and the wet strength was calculated. Wet strength = wet tensile index / dry tensile index × 100%. (2) According to GB / T461.3-2005 "Determination of water absorption of paper and paperboard", the Cobb surface water absorption weight method was used to determine the mass of water absorbed per unit area of ​​the paper after immersion in water. The results are shown in Table 2.

[0035]

[0036] As shown in Table 2, the wet strength agents obtained in Examples 1-3 of this invention significantly improve the wet strength and moisture resistance of paper compared to Comparative Examples 1-2. This is because the cyclic hydrophobic hydrocarbon groups of limonene grafted into the wet strength agent of this invention form hydrophobic microdomains in the polymer network, which can reduce the binding and penetration ability of water molecules with paper fibers and the wet strength agent, and reduce the damage of water molecules to inter-fiber hydrogen bonds, thus helping to improve the moisture resistance and wet strength of the paper. The organically modified montmorillonite can synergistically form with the hydrophobic microdomains constructed by limonene, further improving the wet strength and moisture resistance of the wet strength agent.

[0037] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A method for preparing a high-solids-content moisture-strength agent, characterized in that, Includes the following steps: (1) A dicarboxylic acid and a diamine are reacted at 120-170℃ for 8-12h under the action of an acidic catalyst to obtain a polyamide prepolymer; (2) Cool the polyamide prepolymer obtained in step (1) to 30-60°C, add deionized water to adjust the solid content to 30-50%, and then add allyl glycidyl ether, limonene, organic modified montmorillonite and initiator. After reacting at 50-80°C for 1-3 hours, the polyamide intermediate is obtained. (3) Cool the polyamide intermediate obtained in step (2) to room temperature, add epichlorohydrin dropwise, react at room temperature for 30-90 min, then heat to 50-60℃ and react for 1-4 h, adjust the pH to 3-5, add water to adjust the solid content to 35-45%, and you will get the product.

2. The method for preparing the high solids content wet strength agent according to claim 1, characterized in that, The preparation process of the organically modified montmorillonite in step (2) is as follows: (2-1) Montmorillonite was ultrasonically dispersed in an aqueous ethanol solution, diethylaminomethyltriethoxysilane was added, the pH was adjusted to 4-5, and the reaction was carried out at 50-60℃ for 1-2 hours. After filtration, washing, and vacuum drying, amination montmorillonite was obtained. (2-2) Amine-modified montmorillonite was ultrasonically dispersed in acetonitrile, 1-azido-3-bromopropane was added, and the mixture was reacted at 60-70℃ for 24-36 h. After filtration, washing, and vacuum drying, montmorillonite azido-modified was obtained. (2-3) Azide-modified montmorillonite was ultrasonically dispersed in methanol, and 1-penten-4-yn-3 alcohol, copper sulfate solution and sodium ascorbate solution were added. Under nitrogen protection, the mixture was reacted at 40-50℃ for 15-20 h, filtered, washed and vacuum dried to obtain organically modified montmorillonite.

3. The method for preparing the high solids content wet strength agent according to claim 2, characterized in that, In step (2-1), the ratio of montmorillonite, diethylaminomethyltriethoxysilane and ethanol aqueous solution is 1g:0.6-0.8g:20-30mL; the ethanol aqueous solution is a mixture of ethanol and deionized water in a volume ratio of 1:(2-3).

4. The method for preparing the high solids content wet strength agent according to claim 2, characterized in that, In step (2-2), the ratio of amination montmorillonite, 1-azido-3-bromopropane and acetonitrile is 1g:0.5-0.9g:20-30mL.

5. The method for preparing the high solids content wet strength agent according to claim 2, characterized in that, In steps (2-3), the amounts of montmorillonite azido, 1-penten-4-yn-3 alcohol, copper sulfate solution, sodium ascorbate solution, and methanol are 1g:0.3-0.5g:2-3mL:1-1.5mL:20-30mL; the concentration of copper sulfate solution is 0.1M; and the concentration of sodium ascorbate solution is 1M.

6. The method for preparing the high solids content wet strength agent according to claim 1, characterized in that, In step (1), the molar ratio of dicarboxylic acid, diamine, and acidic catalyst is 1:(0.85-0.95):(0.02-0.03); the dicarboxylic acid is adipic acid and fumaric acid, and the mass ratio of adipic acid to fumaric acid is (5-8):

1.

7. The method for preparing the high solids content wet strength agent according to claim 1, characterized in that, In step (2), the mass ratio of allyl glycidyl ether, limonene, organically modified montmorillonite and initiator is 1:(0.36-0.6):(0.2-0.4):(0.001-0.005); the amount of allyl glycidyl ether is 0.05-0.1 times the molar amount of the dicarboxylic acid.

8. The method for preparing the high solids content wet strength agent according to claim 1, characterized in that, In step (3), the amount of epichlorohydrin used is 0.2-0.5 times the molar amount of the dicarboxylic acid.

9. The method for preparing the high solids content wet strength agent according to claim 1, characterized in that, In step (1), the acidic catalyst is p-toluenesulfonic acid or dodecylbenzenesulfonic acid; the diamine is any one or more of diethylenetriamine, triethylenetetramine, or tetraethylenepentamine; in step (2), the initiator is any one or more of ammonium persulfate, sodium persulfate, or azobisisobutyronitrile.

10. A high solids content moisture strength agent, characterized in that, The high solids content moisture strength agent is prepared according to any one of claims 1-9.

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