Cationic etherifying agent with tackifying effect and preparation method thereof

Abstract

The invention relates to the technical field of fine chemical engineering etherifying agents, and discloses a cationic etherifying agent with a tackifying effect and a preparation method thereof, the etherifying agent is composed of trimethylamine hydrochloride, epichlorohydrin, a compound tackifying modified monomer, a compound catalyst, a compound initiator and deionized water. The preparation process comprises four steps of raw material pretreatment, premixing and initiation, etherification and graft copolymerization, and post-treatment refining, parameters such as pH, temperature, stirring rate and the like in each stage are accurately regulated and controlled, and the tackifying modified monomer is grafted to an etherifying agent main chain to form a three-dimensional network structure through synergism of etherification reaction and free radical graft copolymerization. The product is high in cationic activity, excellent in tackifying effect, high in raw material conversion rate, good in purity, mild and environment-friendly in preparation process and easy to industrialize, solves the problem that a tackifier needs to be additionally added to a traditional etherifying agent, and can be widely applied to the fields of papermaking, spinning, water treatment and the like.

Description

Technical Field

[0001] This invention relates to the field of fine chemical etherifying agents, specifically to a cationic etherifying agent with thickening effect and its preparation method. Background Technology

[0002] Cationic etherifying agents are a class of etherifying reagents with cationic groups (such as tertiary amine groups and quaternary ammonium groups). They are widely used in the cationic modification of polymer materials such as starch and cellulose. By introducing cationic groups, they improve the water solubility, adsorption, and binding ability of polymer materials to the matrix. They have important application value in papermaking, textiles, water treatment, daily chemical industry and other fields.

[0003] Currently, existing cationic etherifying agents, such as 3-chloro-2-hydroxypropyltrimethylammonium chloride and 2,3-epoxypropyltrimethylammonium chloride, primarily focus on cationic modification, exhibiting relatively weak self-tackifying properties. In practical applications, additional tackifiers (such as polyvinyl alcohol and carboxymethyl cellulose) are often required to meet the viscosity requirements of the system. This not only increases production costs but may also lead to decreased system compatibility and performance instability. The limitations of existing etherifying agents are particularly pronounced in scenarios requiring both viscosity and cationic activity, such as interlayer spraying in papermaking, textile sizing, and water treatment flocculation. Inaccurate pH control in traditional processes can easily lead to low raw material conversion rates and impurities, reducing product quality and potentially affecting the stability of thickening in subsequent applications. Furthermore, some preparation processes use highly toxic raw materials and require stringent reaction conditions, which are detrimental to industrial-scale safe production and environmental protection requirements. For example, Chinese patent application CN111875508A discloses a method for preparing a low-cost cationic etherifying agent. Traditional cationic etherifying agents of this type lack long-chain or network thickening groups in their molecular structure, often requiring the addition of additional thickening agents (such as polyvinyl alcohol, carboxymethyl cellulose, etc.) to meet the viscosity requirements of the system in practical applications. This not only increases production costs but may also lead to problems such as decreased system compatibility and unstable performance.

[0004] Therefore, developing a cationic etherifying agent that combines excellent cationic activity and thickening effect, and whose preparation process is simple, environmentally friendly, and produces high-purity products, has become a pressing technical problem to be solved in this field. Summary of the Invention

[0005] In order to overcome the shortcomings of the prior art, the present invention aims to provide a cationic etherifying agent with thickening effect and its preparation method. The etherifying agent has both cationic modification function and thickening function, and the preparation process is simple, environmentally friendly and safe, and suitable for large-scale industrial production.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a cationic etherifying agent with thickening effect, comprising the following weight components: 25-40 parts of trimethylamine hydrochloride, 20-35 parts of epichlorohydrin, 5-15 parts of thickening and modifying monomer, 0.5-3 parts of catalyst, 0.3-2 parts of initiator, and 30-50 parts of deionized water; The thickening and modifying monomer is a compound of acrylamide, hydroxypropyl methylcellulose, and coupling agent-modified cellulose, with a weight ratio of 1:(0.3-0.8):(0.4-0.5). This compound thickening and modifying monomer can form a graft copolymer structure with the etherifying agent, which improves the thickening performance of the product while ensuring cationic activity, and has excellent compatibility with the system.

[0007] Furthermore, the preparation method of the coupling agent modified cellulose is as follows: carboxylated cellulose nanocrystals and dimethyl sulfoxide are added to a reaction flask, ultrasonically treated for 20-25 min, then KH-550 is added, and the reaction is carried out at 75-80℃ for 4-6 h. After the reaction is completed, the lower precipitate is centrifuged, and the lower precipitate is redispersed in anhydrous ethanol and centrifuged again to obtain the coupling agent modified cellulose.

[0008] Furthermore, the ratio of carboxylated cellulose nanocrystals, dimethyl sulfoxide, and KH-550 is 0.8-1g: 18-22mL: 0.05-0.08g.

[0009] Furthermore, the catalyst is a compound of tetrabutylammonium bromide and ferric chloride, with a weight ratio of 1:0.2-0.5. The synergistic effect of the compound catalyst can significantly improve the rate of etherification reaction and the conversion rate of raw materials, and reduce the generation of by-products.

[0010] Furthermore, the initiator is a compound of ammonium persulfate and sodium sulfite, with a weight ratio of 1:0.5-1. This redox initiation system can initiate graft copolymerization under medium and low temperature conditions, and the reaction is mild and easy to control, avoiding the decomposition of raw materials caused by high temperature.

[0011] Furthermore, it includes the following steps: S1. Raw material pretreatment: Add trimethylamine hydrochloride to deionized water, stir until completely dissolved, add pH adjuster to adjust the pH of the system to 3.5-4.5, and set aside; S2. Premixing and initiation: Transfer the trimethylamine hydrochloride aqueous solution pretreated in step (1) into the reactor, heat it to 40-50℃, stir at a speed of 200-300r / min, add the initiator and stir for 10-20min, then slowly add the thickening and modifying monomer and continue stirring for 30-40min to obtain the premixed system; S3. Etherification and graft copolymerization reaction: Slowly add epichlorohydrin to the premixed system at a rate of 1-2 drops / second. After the addition is complete, adjust the pH of the system to 8.4-9.0, add the catalyst, heat to 60-70℃, and maintain the temperature for reaction. During the reaction, stir continuously at a stirring rate of 250-350 r / min. S4. Post-processing and purification: After the reaction is completed, the temperature is lowered to 30-40℃, the pH of the system is adjusted to 5.0-5.5, and the primary product is obtained; after purification, activated carbon decolorization, filtration, vacuum distillation, and cooling to room temperature, the final product is obtained.

[0012] Furthermore, the heat preservation reaction time in S3 is 2-4 hours.

[0013] Furthermore, the temperature of vacuum distillation in S4 is 80-90℃, and the vacuum degree is 0.06-0.08MPa.

[0014] Compared with the prior art, the present invention has the following beneficial technical effects: This invention utilizes a specially formulated thickening and modifying monomer to undergo a graft copolymerization reaction with the etherifying agent, simultaneously introducing cationic groups and thickening side chains into the product's molecular structure. This eliminates the need for additional thickeners to meet viscosity requirements in applications such as papermaking, textiles, and water treatment, effectively reducing application costs. Furthermore, the thickening and modifying monomer exhibits excellent compatibility with the etherifying agent, avoiding issues such as system stratification and performance instability.

[0015] The preparation process uses dilute hydrochloric acid and sodium hydroxide aqueous solution as pH adjusters, which prevents the introduction of impurities and allows for precise control of pH value at each stage. Combined with compound catalysts and initiators, the conversion rate of raw materials is greatly improved and the generation of by-products and impurities is reduced. Subsequent purification, decolorization, filtration, vacuum distillation and other multi-step refining processes further improve the purity of the product and make the cationic activity and thickening properties of the product more stable.

[0016] The reaction conditions of this invention are mild, all carried out at medium and low temperatures and at normal pressure (except for vacuum distillation), requiring no demanding reaction equipment; the raw materials used do not contain highly toxic components, the pH adjuster is a conventional dilute solution of inorganic acid and alkali, no harmful waste gas or residue is generated during the reaction, and unreacted raw materials can be recovered and reused through centrifugal washing, vacuum distillation, etc., which meets the requirements of industrial safety production and environmental protection; at the same time, the process steps are clear and the parameters are easy to control, making it suitable for large-scale industrial production.

[0017] The cationic etherifying agent of the present invention maintains excellent cationic modification effect while possessing good thickening, flocculation and film-forming properties. It can be widely used in many fields such as papermaking interlayer spraying, textile slurry preparation, water treatment flocculation, and daily chemical thickening. It has a significant modification effect on polymer materials such as starch and cellulose, and the water solubility, adsorption and binding force of the modified materials are greatly improved. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely. Obviously, the described embodiments are only some embodiments of the present invention, 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.

[0019] Preparation of carboxylated cellulose nanocrystals: Reference: Li Liling, et al. Food Research and Development, February 2023, Vol. 44, No. 4, pp. 128-135, "Optimization of Preparation Process and Performance Characterization of Carboxylated Cellulose Nanocrystals"; 3.0 g of microcrystalline cellulose (MCC) was weighed and dispersed in a certain amount of citric acid (3 mol / L) solution. Hydrolysis was carried out in a 250 mL flask with mechanical stirring using 6 mol / L hydrochloric acid (20%, volume fraction) as a catalyst. Different temperatures and times were set, and the resulting suspension was repeatedly centrifuged and washed with distilled water until neutral. Then, the suspension was treated in an ultrasonic cell disruptor (1400W) for 30 min to obtain an aqueous solution of carboxylated CNCs. Finally, it was freeze-dried under vacuum for 24 h to obtain carboxylated CNCs powder.

[0020] Example 1 A cationic etherifying agent with thickening effect comprises the following components by weight: 25 parts trimethylamine hydrochloride, 20 parts epichlorohydrin, 5 parts thickening and modifying monomer, 0.5 parts catalyst, 0.3 parts initiator, and 30 parts deionized water; The thickening and modifying monomer is a compound of acrylamide, hydroxypropyl methylcellulose, and coupling agent-modified cellulose, with a weight ratio of 1:0.3:0.4. The catalyst is a mixture of tetrabutylammonium bromide and ferric chloride in a weight ratio of 1:0.2.

[0021] The initiator is a mixture of ammonium persulfate and sodium sulfite in a weight ratio of 1:0.5.

[0022] The preparation method of the coupling agent modified cellulose is as follows: 0.8g of carboxylated cellulose nanocrystals and 18mL of dimethyl sulfoxide are added to a reaction flask, and the mixture is sonicated for 20min. Then, 0.05g of KH-550 is added, and the mixture is reacted at 75℃ for 4-6h. After the reaction is completed, the mixture is centrifuged, and the lower precipitate is redispersed in anhydrous ethanol. After further centrifugation, the coupling agent modified cellulose is obtained.

[0023] Preparation method: S1. Raw material pretreatment: Add trimethylamine hydrochloride to deionized water and stir until completely dissolved. Add 10% dilute hydrochloric acid solution to adjust the pH of the system to 3.5 and set aside. S2. Premixing and initiation: The trimethylamine hydrochloride aqueous solution pretreated in step (1) is transferred into the reactor, heated to 40°C, stirred at a rate of 200 r / min, and initiator is added and stirred for 10 min. Then, the thickening and modifying monomer is slowly added and stirred for another 30 min to obtain the premixed system. S3. Etherification and graft copolymerization reaction: Epichlorohydrin was slowly added dropwise to the premixed system at a rate of 1-2 drops / second. A 10% sodium hydroxide aqueous solution was added to adjust the pH of the system to 8.4. The catalyst was added, the temperature was raised to 60℃, and the reaction was maintained at this temperature for 2 hours. During this period, the mixture was continuously stirred at a stirring rate of 250 r / min. S4. Post-processing and purification: After the reaction is completed, the temperature is lowered to 30℃, and a 10% (w / w) dilute hydrochloric acid solution is added to adjust the pH of the system to 5.0 to obtain the primary product. After purification, decolorization with activated carbon, and filtration, the product is distilled under reduced pressure at 80℃ and 0.06MPa, and then cooled to room temperature to obtain the final product.

[0024] Example 2 A cationic etherifying agent with thickening effect comprises the following components by weight: 32 parts trimethylamine hydrochloride, 28 parts epichlorohydrin, 10.5 parts thickening and modifying monomer, 1.8 parts catalyst, 1.2 parts initiator, and 40 parts deionized water; The thickening and modifying monomer is a compound of acrylamide, hydroxypropyl methylcellulose, and coupling agent-modified cellulose, with a weight ratio of 1:0.5:0.45. The catalyst is a mixture of tetrabutylammonium bromide and ferric chloride in a weight ratio of 1:0.75.

[0025] The initiator is a mixture of ammonium persulfate and sodium sulfite in a weight ratio of 1:0.75.

[0026] The preparation method of the coupling agent modified cellulose is as follows: 0.9g of carboxylated cellulose nanocrystals and 20mL of dimethyl sulfoxide are added to a reaction flask, ultrasonically treated for 22min, and then 0.07g of KH-550 is added. The reaction is carried out at 78℃ for 5h. After the reaction is completed, the mixture is centrifuged, and the lower precipitate is redispersed in anhydrous ethanol. The mixture is then centrifuged again to obtain the coupling agent modified cellulose.

[0027] Preparation method: S1. Raw material pretreatment: Add trimethylamine hydrochloride to deionized water and stir until completely dissolved. Add 10% dilute hydrochloric acid solution to adjust the pH of the system to 4 and set aside. S2. Premixing and initiation: The trimethylamine hydrochloride aqueous solution pretreated in step (1) is transferred into the reactor, heated to 45°C, stirred at a speed of 250 r / min, and initiator is added and stirred for 15 min. Then, the thickening and modifying monomer is slowly added and stirred for another 35 min to obtain the premixed system. S3. Etherification and graft copolymerization reaction: Epichlorohydrin was slowly added dropwise to the premixed system at a rate of 1 drop / second. A 10% sodium hydroxide aqueous solution was added to adjust the pH of the system to 8.7. The catalyst was added, the temperature was raised to 65°C, and the reaction was maintained at this temperature for 3 hours. During this period, the mixture was continuously stirred at a stirring rate of 300 r / min. S4. Post-processing and purification: After the reaction is completed, the temperature is lowered to 35℃, and a 10% (w / w) dilute hydrochloric acid solution is added to adjust the pH of the system to 5.3 to obtain the primary product. After purification, decolorization with activated carbon, and filtration, the product is distilled under reduced pressure at 85℃ and 0.07MPa, and then cooled to room temperature to obtain the final product.

[0028] Example 3 A cationic etherifying agent with thickening effect comprises the following components by weight: 40 parts trimethylamine hydrochloride, 35 parts epichlorohydrin, 15 parts thickening and modifying monomer, 3 parts catalyst, 2 parts initiator, and 50 parts deionized water. The thickening and modifying monomer is a compound of acrylamide, hydroxypropyl methylcellulose, and coupling agent-modified cellulose, with a weight ratio of 1:0.8:0.5. The catalyst is a mixture of tetrabutylammonium bromide and ferric chloride in a weight ratio of 1:0.5.

[0029] The initiator is a mixture of ammonium persulfate and sodium sulfite in a weight ratio of 1:1.

[0030] The preparation method of the coupling agent modified cellulose is as follows: 1g of carboxylated cellulose nanocrystals and 22mL of dimethyl sulfoxide are added to a reaction flask, ultrasonically treated for 25min, and then 0.08g of KH-550 is added. The reaction is carried out at 80℃ for 6h. After the reaction is completed, the lower precipitate is centrifuged and redispersed in anhydrous ethanol. The mixture is then centrifuged again to obtain the coupling agent modified cellulose.

[0031] Preparation method: S1. Raw material pretreatment: Add trimethylamine hydrochloride to deionized water, stir until completely dissolved, add 10% dilute hydrochloric acid solution to adjust the pH of the system to 4.5, and set aside; S2. Premixing and initiation: The trimethylamine hydrochloride aqueous solution pretreated in step (1) is transferred into the reactor, heated to 50°C, stirred at a rate of 300 r / min, and initiator is added and stirred for 20 min. Then, the thickening and modifying monomer is slowly added and stirred for another 40 min to obtain the premixed system. S3. Etherification and graft copolymerization reaction: Epichlorohydrin was slowly added dropwise to the premixed system at a rate of 2 drops / second. A 10% sodium hydroxide aqueous solution was added to adjust the pH of the system to 9.0. The catalyst was added, the temperature was raised to 70℃, and the reaction was maintained at this temperature for 4 hours. During this period, the mixture was continuously stirred at a stirring rate of 350 r / min. S4. Post-processing and purification: After the reaction is completed, the temperature is lowered to 40℃, and a 10% (w / w) dilute hydrochloric acid solution is added to adjust the pH of the system to 5.5 to obtain the primary product. After purification, decolorization with activated carbon, and filtration, the product is distilled under reduced pressure at 90℃ and 0.08MPa, and then cooled to room temperature to obtain the final product.

[0032] Comparative Example 1 The difference between this comparative example and Example 3 is that acrylamide was used instead of the thickening and modifying monomer.

[0033] Comparative Example 2 The difference between this comparative example and Example 3 is that carboxylated cellulose nanocrystals were used instead of coupling agent-modified cellulose.

[0034] Comparative Example 3 The difference between this comparative example and Example 3 is that the catalyst was replaced with a single tetrabutylammonium bromide (3 parts), and the ferric chloride compound was omitted.

[0035] Comparative Example 4 Compared to Example 3, the difference in this comparative example is that the total amount of thickening and modifying monomers is changed to 20 parts (exceeding the range of 5-15 parts), while the ratio remains 1:0.8:0.5.

[0036] Comparative Example 5 The difference between this comparative example and Example 3 is that the epichlorohydrin dropping rate was changed to 3 drops / second (exceeding the range of 1-2 drops / second).

[0037] Viscosity test of 1% aqueous solution: Prepare the finished product into an aqueous solution with a certain mass fraction (1%), and measure its apparent viscosity (unit: mPa·s) at room temperature (e.g., 25℃) using a rotational viscometer.

[0038] Cationic activity (degree of substitution / cationicity) test: The concentration of the solution in the product is determined by colloidal titration, and the degree of cation substitution is calculated.

[0039] Raw material conversion rate test: Raw material conversion rate test (high performance liquid chromatography, HPLC) Weigh the epichlorohydrin precisely before the reaction and record the initial feed amount; After the reaction is complete, take an appropriate amount of the purified product, dissolve it in methanol and make up to volume, filter it through a 0.22μm organic filter membrane to obtain the sample solution to be tested; The amount of unreacted epichlorohydrin residue in the sample solution was detected by high performance liquid chromatography. The conversion rate of raw materials (%) was calculated according to the formula: (initial feed amount - residual amount) / initial feed amount × 100%. The average value of the conversion rates of the two core raw materials was taken as the final result.

[0040] Storage stability test: The finished product to be tested was sealed in a transparent reagent bottle and stored in a high temperature (40℃) environment for 30 days; After storage, the viscosity of its 1% aqueous solution is tested. The viscosity retention rate (%) is calculated according to the formula = viscosity after storage / initial viscosity × 100%. A viscosity retention rate of ≥90% is considered qualified.

[0041] Table 1: Performance Tests project Apparent viscosity (mPa·s) Cationicity (mmol / g) Raw material conversion rate (%) Viscosity retention rate (%) after 30 days of storage at 40℃ Example 1 1100 1.93 92.6 93.5 Example 2 1200 1.92 94.0 94.2 Example 3 1550 1.95 96.2 93.4 Comparative Example 1 420 1.90 95.5 91.2 Comparative Example 2 950 1.85 91.1 82.3 Comparative Example 3 1480 1.25 74.2 86.5 Comparative Example 4 6000 1.40 93.5 81.1 Comparative Example 5 780 0.85 58.3 79.6 Table 1 shows that in Comparative Example 1, the compounding process was eliminated, and only single acrylamide was used, replacing the compounded thickening and modifying monomers. Data showed a decrease in apparent viscosity, reaching only 420 mPa·s (compared to 1550 mPa·s in Example 3). Analysis: Using only acrylamide resulted in the absence of the macromolecular framework provided by cellulose, preventing the effective formation of a three-dimensional network graft copolymer structure with the etherifying agent, thus losing its excellent thickening effect.

[0042] Comparative Example 2: No KH-550 coupling agent modification was performed. Differences in variables: Unmodified carboxylated cellulose nanocrystals were used instead of KH-550 modified cellulose. Data performance: The viscosity retention rate decreased significantly to 82.3% after 30 days of storage at 40°C (compared to 93.4% in Example 3), and the initial viscosity also decreased (950 mPa·s).

[0043] Cause analysis: KH-550 modification aims to improve the compatibility of the thickening monomer with the system, enabling it to better participate in graft copolymerization. Unmodified cellulose nanocrystals lack effective reactive groups, resulting in their inability to stably attach to the main chain, leading to poor system compatibility and potential performance instability (low viscosity retention) after prolonged storage.

[0044] Comparative Example 3: Synergistic Effect of Missing Composite Catalysts Differences in variables: Only tetrabutylammonium bromide was used as the catalyst, and the ferric chloride compound was omitted. Data performance: The feed conversion rate plummeted to 74.2% (96.2% in Example 3), and the cation content decreased significantly to 1.25 mmol / g.

[0045] Cause analysis: The combined catalyst (tetrabutylammonium bromide + ferric chloride) has a synergistic effect, aiming to significantly improve the rate of etherification reaction and the conversion rate of raw materials, while reducing the formation of by-products. Removing ferric chloride eliminates this synergistic effect, resulting in a large amount of raw materials failing to undergo the etherification grafting reaction successfully, directly lowering the overall conversion rate and the cationic activity of the product.

[0046] Comparative Example 4: Severely excessive thickening monomer Differences in variables: The total amount of thickening and modifying monomers increased to 20 parts, exceeding the preferred range of 5-15 parts.

[0047] Data Performance: Viscosity abnormally spiked to 6000 mPa·s, while cationicity decreased to 1.40 mmol / g, and viscosity retention dropped to 81.1%. Analysis: Although thickening monomers can increase viscosity, excessive addition leads to over-crosslinking of the system, resulting in excessively high viscosity (potentially causing poor water solubility and flowability). Furthermore, the over-crosslinked structure is more susceptible to damage during prolonged high-temperature storage, leading to decreased stability (retention rate).

[0048] Comparative Example 5: Process parameters out of control (dropping acceleration too fast) Difference in variables: The dropping rate of epichlorohydrin was changed to 3 drops / second, far exceeding the specified 1-2 drops / second.

[0049] Data performance: All indicators collapsed. The raw material conversion rate was extremely low (58.3%), the cationicity dropped to the lowest level (0.85 mmol / g), and the viscosity (780 mPa·s) and retention rate (79.6%) were also low.

[0050] Cause Analysis: The dropwise addition of epichlorohydrin is usually exothermic or requires a specific reaction rhythm. Adding too quickly can lead to excessively high local concentrations, triggering numerous side reactions (such as ineffective ring-opening hydrolysis of epoxy groups). This not only wastes the core reaction raw materials (resulting in extremely low conversion rates) but also prevents the expected cationization and etherification reactions from proceeding normally, severely impacting the quality and stability of the final product.

[0051] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0052] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

[0053] Those skilled in the art should understand that the above descriptions are merely several specific embodiments of the present invention, and not all embodiments.

Claims

1. A cationic etherifying agent with a thickening effect, characterized in that, It comprises the following components by weight: 25-40 parts trimethylamine hydrochloride, 20-35 parts epichlorohydrin, 5-15 parts thickening and modifying monomer, 0.5-3 parts catalyst, 0.3-2 parts initiator, and 30-50 parts deionized water; The thickening and modifying monomer is a compound of acrylamide, hydroxypropyl methylcellulose, and coupling agent-modified cellulose, with a weight ratio of 1:(0.3-0.8):(0.4-0.5). During the preparation of the cationic etherifying agent with thickening effect, the dropping rate of epichlorohydrin is 1-2 drops / second.

2. The cationic etherifying agent with thickening effect according to claim 1, characterized in that, The preparation method of the coupling agent modified cellulose is as follows: carboxylated cellulose nanocrystals and dimethyl sulfoxide are added to a reaction flask, ultrasonically treated for 20-25 min, then KH-550 is added, and the reaction is carried out at 75-80℃ for 4-6 h. After the reaction is completed, the mixture is centrifuged, and the lower precipitate is redispersed in anhydrous ethanol and centrifuged again to obtain the coupling agent modified cellulose.

3. The cationic etherifying agent with thickening effect according to claim 2, characterized in that, The ratio of carboxylated cellulose nanocrystals, dimethyl sulfoxide, and KH-550 is 0.8-1g: 18-22mL: 0.05-0.08g.

4. The cationic etherifying agent with thickening effect according to claim 1, characterized in that, The catalyst is a mixture of tetrabutylammonium bromide and ferric chloride, with a weight ratio of 1:0.2-0.

5.

5. The cationic etherifying agent with thickening effect according to claim 1, characterized in that, The initiator is a compound of ammonium persulfate and sodium sulfite, with a weight ratio of 1:0.5-1.

6. A method for preparing a cationic etherifying agent with thickening effect as described in any one of claims 1-5, characterized in that, Includes the following steps: S1. Raw material pretreatment: Add trimethylamine hydrochloride to deionized water and stir until completely dissolved. Add a pH adjuster to adjust the pH of the system to 3.5-4.5 and set aside. The pH adjuster is a 10% (w / w) dilute hydrochloric acid solution. S2. Premixing and initiation: Transfer the trimethylamine hydrochloride aqueous solution pretreated in step (1) into the reactor, heat it to 40-50℃, stir at a speed of 200-300r / min, add the initiator and stir for 10-20min, then slowly add the thickening and modifying monomer and continue stirring for 30-40min to obtain the premixed system; S3. Etherification and graft copolymerization reaction: Epichlorohydrin is slowly added dropwise to the premixed system at a rate of 1-2 drops / second. After the addition is complete, the pH of the system is adjusted to 8.4-9.0, the catalyst is added, the temperature is raised to 60-70℃, and the reaction is maintained at this temperature with continuous stirring at a stirring rate of 250-350 r / min. The pH of the system is adjusted using a 10% (w / w) sodium hydroxide aqueous solution. S4. Post-processing and purification: After the reaction is completed, the temperature is lowered to 30-40℃, and the pH of the system is adjusted to 5.0-5.5 to obtain the primary product; after purification, activated carbon decolorization, filtration, vacuum distillation, and cooling to room temperature, the finished product is obtained; the pH of the system is adjusted using a 10% (w / w) dilute hydrochloric acid solution.

7. The method for preparing the cationic etherifying agent with thickening effect according to claim 6, characterized in that, The heat preservation reaction time in S3 is 2-4 hours.

8. The method for preparing the cationic etherifying agent with thickening effect according to claim 6, characterized in that, The vacuum distillation in S4 is carried out at a temperature of 80-90℃ and a vacuum degree of 0.06-0.08MPa.