A di-ionic side group modified carboxymethyl cellulose and a method for preparing the same
Patent Information
- Application Number
- CN202611104313.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-07-24
- Publication Date
- 2026-08-21
AI Technical Summary
[0005]本发明的目的在于提供一种双离子侧基改性羧甲基纤维素及其制备方法，以解决羧甲基纤维素在含电解质尤其含二价金属离子的介质中易发生溶解性下降、析出增多和黏度衰减的问题
1.本发明在羧甲基纤维素骨架上同时引入第一固定环状季铵阳离子侧基和第二吡啶鎓羧基甜菜碱离子侧基；第一固定环状季铵阳离子侧基能够提供固定的阳离子水化锚点，第二吡啶鎓羧基甜菜碱离子侧基能够提供内盐型强水化结构和局部电荷缓冲环境；得到的双离子侧基改性羧甲基纤维素在含电解质尤其是Ca2+、Mg2+共存介质中具有更高的透光率、更低的不溶物率以及更高的溶解保持率。
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Abstract
Description
Technical Field
[0001] This invention relates to the field of polysaccharide derivatives technology, specifically to a biionic side-group modified carboxymethyl cellulose and its preparation method. Background Technology
[0002] Carboxymethyl cellulose and its salts are widely used in various water-based systems due to their good water solubility, thickening properties, suspension properties, and rheology regulation capabilities. However, in practical applications, the system often contains sodium (Na₂O₃). + Ca 2+ Mg 2+ Electrolyte ions, especially those containing Ca 2+ and Mg 2+ In complex ionic environments, the carboxylate sites on carboxymethyl cellulose chains readily undergo electrostatic association and ion bridging with divalent ions, leading to chain conformational shrinkage, inter-chain aggregation, decreased solubility, increased precipitation, and reduced viscosity retention, thus limiting its application in complex ionic environments.
[0003] In existing technologies, to improve the adaptability of cellulose derivatives in ionic media, methods such as introducing a single cationic group, introducing zwitterionic groups, or introducing other polar hydrophilic side groups are commonly used to enhance the hydration capacity and dispersion stability of the polymer chain. However, single-side-group modification routes often struggle to simultaneously achieve a fixed positive potential point, a locally strong hydration structure, and stable dispersion and rheological retention under complex electrolyte conditions, especially in the presence of divalent ions.
[0004] Therefore, it remains necessary to provide a new carboxymethyl cellulose modification scheme to achieve good performance in electrolyte media, especially in Ca2+. 2+ Mg 2+ Materials with better overall performance in coexisting systems. Summary of the Invention
[0005] The purpose of this invention is to provide a dual-ion side-group modified carboxymethyl cellulose and its preparation method, so as to solve the problems of decreased solubility, increased precipitation and viscosity decay of carboxymethyl cellulose in media containing electrolytes, especially divalent metal ions.
[0006] To achieve the above objectives, the present invention adopts the following technical solution: This invention provides a dual-ion side-group modified carboxymethyl cellulose, wherein the dual-ion side-group modified carboxymethyl cellulose uses carboxymethyl cellulose as a backbone and contains a first fixed cyclic quaternary ammonium cation side group and a second pyridinium carboxybetaine ion side group.
[0007] This invention also provides a method for preparing the dual-ionic side-group modified carboxymethyl cellulose, comprising the following steps: Step (1) Disperse sodium carboxymethyl cellulose in a mixed medium, add alkaline solution for alkalization and activation, and then add epichlorohydrin to react and obtain an intermediate containing a reactive chlorohydroxypropyl site; In the above process, sodium carboxymethyl cellulose undergoes alkaline activation under alkaline conditions, which puts some of the hydroxyl groups on the molecular chain into an activated state that is more prone to nucleophilic reactions. Subsequently, epichlorohydrin is introduced to react with the active sites on the carboxymethyl cellulose backbone, introducing chlorohydroxypropyl sites on the molecular chain that can further react.
[0008] Step (2) The intermediate containing the reactive chlorohydroxypropyl site is dispersed in a mixed medium of water and ethanol, and 1-methylpiperidine is added to react and introduce the first fixed cyclic quaternary ammonium cation side group to obtain the first ionic intermediate; In the above process, 1-methylpiperidine, as a nitrogen-containing nucleophile, undergoes a substitution reaction with the reactive chlorohydroxypropyl site introduced in step (1) to form a fixed cyclic quaternary ammonium cation side group on the carboxymethyl cellulose backbone.
[0009] Step (3) react methyl nicotinate with epichlorohydrin to obtain a reactive pyridinium intermediate, and then graft the reactive pyridinium intermediate with the first ionic intermediate to obtain an esterified intermediate; In the above process, the pyridine ring nitrogen atom in methyl nicotinate reacts with epichlorohydrin to form a reactive pyridinium intermediate; the pyridinium intermediate further undergoes a grafting reaction with the reactive site on the molecular chain of the first ionic intermediate, thereby introducing the ester-type second side group into the carboxymethyl cellulose backbone.
[0010] Step (4) The esterification intermediate obtained in step (3) is dispersed in an alcohol-water system, and an alkaline solution is added for hydrolysis to convert the second side group of the ester type into the second pyridinium carboxybetaine ion side group. After the reaction is completed, the mixture is neutralized, purified and dried to obtain the dual ion side group modified carboxymethyl cellulose.
[0011] In the above process, the ester-type second side group in the esterification intermediate undergoes hydrolysis under alkaline conditions, converting the ester group into a carboxyl group. This carboxyl group then forms an inner salt-type pyridinium carboxybetaine ion side group together with the original pyridinium cation moiety in the molecule. After this step, the resulting product simultaneously possesses a first fixed cyclic quaternary ammonium cation side group and a second pyridinium carboxybetaine ion side group, thereby constructing a dual-ion side group synergistic structure on the material's molecular chain.
[0012] Furthermore, the first fixed cyclic quaternary ammonium cation side group is derived from the nucleophilic substitution reaction between 1-methylpiperidine and the intermediate containing the reactive chlorohydroxypropyl site; the second pyridinium carboxybetaine ion side group is derived from the grafting of a reactive pyridinium intermediate formed by methyl nicotinate and epichlorohydrin, followed by alkaline hydrolysis.
[0013] Further, in step (1), the mixing medium is a mixture of isopropanol and water, and the volume ratio of isopropanol to water is 5:1 to 10:1.
[0014] Further, in step (1), the ratio of epichlorohydrin to sodium carboxymethyl cellulose is 0.2-1.0 mL:1 g; the alkaline solution is a sodium hydroxide aqueous solution with a mass fraction of 5-20%; the reaction temperature is 25-45℃, and the reaction time is 2-8 h.
[0015] Further, in step (2), the volume ratio of water to ethanol is 3:7 to 7:3; the mass ratio of 1-methylpiperidine to the intermediate containing the reactive chlorohydroxypropyl site is 0.2 to 1.2:1; the reaction temperature is 50 to 80°C; and the reaction time is 4 to 12 h.
[0016] Furthermore, in step (2), after the reaction is completed, it is preferable to use a dialysis bag or ultrafiltration membrane with a molecular weight cutoff of 5 to 20 kDa for desalting and purification.
[0017] Furthermore, in step (3), methyl nicotinic acid and epichlorohydrin are preferably reacted in anhydrous acetonitrile, ethanol or a mixture thereof, at a reaction temperature of 55-65°C and a reaction time of 8-12 h.
[0018] Furthermore, in step (3), the pH of the grafting reaction system is controlled at 8.0 to 10.5, the reaction temperature is 40 to 70°C, and the reaction time is 6 to 16 hours.
[0019] Further, in step (4), the volume ratio of alcohol to water in the alcohol-water system is 1:3 to 3:1, and the alcohol is methanol or ethanol.
[0020] Further, in step (4), the alkaline solution is a sodium hydroxide solution; after adding the alkaline solution, the pH of the system is controlled at 10.0 to 11.0, the reaction temperature is 35 to 45°C, and the reaction time is 4 to 8 h; after the reaction is completed, the pH is preferably adjusted to 6.5 to 7.5 with acid, and low molecular weight byproducts and inorganic salts are removed by dialysis, ultrafiltration or repeated alcohol washing.
[0021] Furthermore, the dual-ion side-group modified carboxymethyl cellulose obtained by this invention can be used to improve the solubility, dispersion stability and rheological retention in electrolyte-containing media.
[0022] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are: 1. This invention simultaneously introduces a first fixed cyclic quaternary ammonium cation side group and a second pyridinium carboxybetaine ion side group onto the carboxymethyl cellulose backbone; the first fixed cyclic quaternary ammonium cation side group can provide a fixed cation hydration anchor, and the second pyridinium carboxybetaine ion side group can provide an internal salt-type strong hydration structure and a local charge buffering environment; the resulting dual-ion side group modified carboxymethyl cellulose can withstand electrolytes, especially Ca... 2+ Mg 2+ It exhibits higher light transmittance, lower insoluble content, and higher solubility retention in the coexisting medium.
[0023] 2. In this invention, the alkaline hydrolysis in step (4) converts the second ester-type side group into a second pyridinium carboxylated betaine ion side group, which is beneficial to improving the ionization degree and stable hydration ability of the side group, reducing the performance limitations of the ester-type precursor in the composite electrolyte medium, and enabling the dual-ion side group modified carboxymethyl cellulose to be hydrated in Ca2+ electrolytes. 2+ Mg 2+ The coexisting system exhibits better precipitation inhibition, sustained stability, and viscosity retention.
[0024] 3. By controlling the reaction conditions in steps (1) to (4), this invention facilitates the effective introduction of the first fixed cyclic quaternary ammonium cation side group and the second pyridinium carboxylic betaine ion side group, thereby achieving a better overall balance between solubility, dispersion stability and rheological retention ability in the obtained dual-ion side group modified carboxymethyl cellulose. Attached Figure Description
[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0026] Figure 1 This is a process flow diagram for preparing the dual-ion side-group modified carboxymethyl cellulose of the present invention.
[0027] Figure 2 This is a graph showing the viscosity retention rate of a representative sample of the dual-ion side-group modified carboxymethyl cellulose of the present invention under different total hardness conditions in a hard water gradient system where CaCl2 and MgCl2 coexist.
[0028] Figure 3 This is a graph showing the change in insoluble content of a representative sample of the dual-ion side-group modified carboxymethyl cellulose of the present invention under different total hardness conditions in a hard water gradient system where CaCl2 and MgCl2 coexist.
[0029] Figure 4This is a comparison chart of the transmittance of various samples of the dual-ion side-group modified carboxymethyl cellulose of the present invention in a composite hard water system with CaCl2 and MgCl2 coexisting (total hardness of 3000 mg / L, calculated as CaCO3).
[0030] Figure 5 This is a comparison chart of the viscosity retention rate of various samples of the dual-ion side-group modified carboxymethyl cellulose of the present invention in a CaCl2 and MgCl2 coexisting system over 7 days. Detailed Implementation
[0031] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0032] The sodium carboxymethyl cellulose used in this application is a commercially available product. The degree of substitution (DS) of the sodium carboxymethyl cellulose is 0.65–0.90; the average molecular weight is approximately 250,000; the viscosity of its aqueous solution is 200–500 mPa·s for a 1% aqueous solution (at 25°C); and the loss on drying is not higher than 10.0%. Before use, the sodium carboxymethyl cellulose is dried to constant weight at 60°C or for at least 8 hours. Example 1
[0033] This embodiment discloses a method for preparing biionic side-group modified carboxymethyl cellulose, including the following steps: Step (1) Weigh 10g of dried sodium carboxymethyl cellulose and add it to a mixed medium consisting of 300mL isopropanol and 40mL deionized water. After dispersing at room temperature for 30min, add 20mL of 10% sodium hydroxide aqueous solution for alkalization and activation. Then add 8mL of epichlorohydrin and react at 40℃ for 4h. Filter and wash to obtain an intermediate containing a reactive chlorohydroxypropyl site.
[0034] Step (2) The above intermediate was dispersed in a mixed medium consisting of 250 mL of deionized water and 250 mL of ethanol. 6 g of 1-methylpiperidine was added and reacted at 60 °C for 8 h. After the reaction was completed, the intermediate was desalted and purified using a 10 kDa dialysis bag. The intermediate was dialyzed in deionized water for 36 h, and the dialysate was replaced every 10 h until the conductivity of the external liquid was close to that of deionized water, thus obtaining the first ionic intermediate.
[0035] Step (3) Take another 3g of methyl nicotinate and add it to 80mL of anhydrous acetonitrile. After stirring and dissolving, add 4mL of epichlorohydrin and react at 60℃ for 10h to obtain a reactive pyridinium intermediate reaction solution. Add the reaction solution to the above first ionic intermediate dispersion, adjust the pH of the system to 9.0, and react at 55℃ for 10h to obtain an esterification intermediate.
[0036] Step (4) The obtained esterification intermediate was dispersed in an alcohol-water system consisting of 150 mL methanol and 150 mL deionized water. Sodium hydroxide solution was added to adjust the pH of the system to 10.5. The reaction was carried out at 40 °C for 6 h. After the reaction was completed, the pH was adjusted to 7.0 with dilute hydrochloric acid. After purification by dialysis, ultrafiltration or repeated alcohol washing, the product was dried and dried under reduced pressure at 50 °C to constant weight to obtain biionic side-group modified carboxymethyl cellulose. Example 2
[0037] This embodiment discloses a method for preparing biionic side-group modified carboxymethyl cellulose, including the following steps: Step (1) Weigh 10g of dried sodium carboxymethyl cellulose and add it to a mixed medium consisting of 250mL isopropanol and 50mL deionized water. Add 15mL of 5% sodium hydroxide aqueous solution for alkalization and activation. Then add 2mL of epichlorohydrin and react at 25℃ for 2h to obtain an intermediate containing a reactive chlorohydroxypropyl site.
[0038] Step (2) The intermediate was dispersed in a mixed medium consisting of 150 mL of deionized water and 350 mL of ethanol, and 2 g of 1-methylpiperidine was added. The mixture was reacted at 50 °C for 4 h. After desalting and purification, the first ionic intermediate was obtained.
[0039] Step (3) methyl nicotinate and epichlorohydrin were reacted in ethanol at 55°C for 8 hours to obtain a reactive pyridinium intermediate, which was then grafted with the first ionic intermediate at pH 8.0 and 40°C for 6 hours to obtain an esterified intermediate.
[0040] Step (4) The esterification intermediate was dispersed in an alcohol-water system with a volume ratio of ethanol and water of 1:3, the pH of the system was adjusted to 10.0, and the reaction was carried out at 35°C for 4 hours. After post-treatment, neutralization, purification and drying were performed to obtain biionic side-group modified carboxymethyl cellulose. Example 3
[0041] This embodiment discloses a method for preparing biionic side-group modified carboxymethyl cellulose, including the following steps: Step (1) Weigh 10g of dried sodium carboxymethyl cellulose and add it to a mixed medium consisting of 400mL isopropanol and 40mL deionized water. Add 25mL of sodium hydroxide aqueous solution with a mass fraction of 20% for alkalization and activation. Then add 10mL of epichlorohydrin and react at 45℃ for 8h to obtain an intermediate containing a reactive chlorohydroxypropyl site.
[0042] Step (2) The intermediate was dispersed in a mixed medium consisting of 350 mL of deionized water and 150 mL of ethanol, and 12 g of 1-methylpiperidine was added. The mixture was reacted at 80 °C for 12 h. After desalting and purification, the first ionic intermediate was obtained.
[0043] Step (3) methyl nicotinate and epichlorohydrin were reacted in a mixed solvent of acetonitrile and ethanol at 65°C for 12 h to obtain a reactive pyridinium intermediate; then, the intermediate was grafted with the first ionic intermediate at pH 10.5 and 70°C for 16 h to obtain an esterified intermediate.
[0044] Step (4) The esterification intermediate was dispersed in an alcohol-water system with a volume ratio of methanol and water of 3:1. The pH of the system was adjusted to 11.0 and reacted at 45°C for 8 hours. After neutralization, purification and drying, the biionic side-group modified carboxymethyl cellulose was obtained. Example 4
[0045] This embodiment discloses a method for preparing biionic side-group modified carboxymethyl cellulose, including the following steps: Step (1) Weigh 10g of dried sodium carboxymethyl cellulose and add it to a mixed medium consisting of 300mL isopropanol and 50mL deionized water. Add 18mL of sodium hydroxide aqueous solution with a mass fraction of 12% for alkalization and activation. Then add 6mL of epichlorohydrin and react at 35℃ for 5h to obtain an intermediate containing a reactive chlorohydroxypropyl site.
[0046] Step (2) The intermediate was dispersed in a mixed medium consisting of 200 mL of deionized water and 300 mL of ethanol, and 5 g of 1-methylpiperidine was added. The mixture was reacted at 65 °C for 8 h. After desalting and purification, the first ionic intermediate was obtained.
[0047] Step (3) methyl nicotinate and epichlorohydrin are reacted in ethanol at 60°C for 10 h to obtain a reactive pyridinium intermediate, which is then grafted with the first ionic intermediate at pH 9.5 and 60°C for 12 h to obtain an esterified intermediate.
[0048] Step (4) The esterification intermediate was dispersed in an alcohol-water system with a volume ratio of 1:1 of ethanol and water, the pH of the system was adjusted to 10.8, and the reaction was carried out at 42°C for 6 hours. After post-treatment, neutralization, purification and drying were performed to obtain biionic side-group modified carboxymethyl cellulose.
[0049] Comparative Example 1 Comparative Example 1 was not modified in any way and sodium carboxymethyl cellulose was used directly as the sample.
[0050] Comparative Example 2 Compared with Example 1, Comparative Example 2 followed the steps (1) and (2) of Example 1. After obtaining the first ionic intermediate, steps (3) and (4) were not performed. The sample was obtained after purification and drying.
[0051] Comparative Example 3 Compared with Example 1, Comparative Example 3 was performed according to the steps of Example 1 (1), and then without adding 1-methylpiperidine, the intermediate obtained in step (1) was directly grafted with the reactive pyridinium intermediate formed by methyl nicotinate and epichlorohydrin, and the hydrolysis, neutralization, purification and drying in step (4) were continued to obtain the sample.
[0052] Comparative Example 4 Compared with Example 1, Comparative Example 4 followed steps (1) to (3) of Example 1, but did not perform the hydrolysis treatment in step (4). The esterification intermediate was directly purified and dried as a sample.
[0053] Comparative Example 5 Compared with Example 1, Comparative Example 5 did not change the preparation route of the single-sided sample. The samples obtained from Comparative Example 2 and Comparative Example 3 were taken and physically blended at a dry basis mass ratio of 1:1. The samples were then prepared in deionized water to form a sample solution with the same concentration as in Example 1. The solution was stirred and hydrated at 25°C for 4 hours. If necessary, it was allowed to stand to remove bubbles before use.
[0054] Performance testing methods Each sample was first prepared as a 1.0 wt% aqueous solution, stirred and hydrated at 25°C for 4 hours, and allowed to stand to remove bubbles if necessary before use.
[0055] To examine the adaptability of each sample to different ionic environments, the following test media were prepared: a NaCl single-salt system, a CaCl2 single-salt system, a MgCl2 single-salt system, a CaCl2 and MgCl2 coexistence system, and a NaCl and CaCl2 coexistence system. Unless otherwise specified, each test system was prepared by mixing the sample solution with the corresponding electrolyte stock solution to achieve a final polymer concentration of 0.5 wt%.
[0056] Among the representative ionic media shown in Table 1, the NaCl system uses 0.50 mol / L NaCl, the CaCl2 system uses 20 mmol / L CaCl2, the MgCl2 system uses 20 mmol / L MgCl2, and the CaCl2 and MgCl2 coexistence system uses CaCl2. 2+ With Mg 2+The molar ratio was 2:1 and the total hardness was 3000 mg / L (calculated as CaCO3). The NaCl and CaCl2 system was designed with 0.30 mol / L NaCl and 10 mmol / L CaCl2 in coexistence.
[0057] Table 2 shows the hard water gradient system in which CaCl2 and MgCl2 coexist. (CaCl2 and MgCl2 are listed in Table 2.) 2+ With Mg 2+ The molar ratio was 2:1 for all samples, and the total hardness was set at 500 mg / L, 1000 mg / L, 3000 mg / L, and 5000 mg / L, respectively, as CaCO3. The mixed system was allowed to stand at 25℃ for 24 hours before testing.
[0058] Transmittance was measured using a 1cm cuvette at a wavelength of 600nm, with a blank medium free of polymers under corresponding ionic conditions used as a reference.
[0059] The method for testing the insoluble content is as follows: After allowing the sample system to stand for a specified time, centrifuge, collect the precipitate, wash with deionized water, and dry to constant weight. The insoluble content is calculated using the following formula: Insoluble matter percentage (%) = (dry weight of precipitate / initial dry weight of sample) × 100%.
[0060] The method for testing the solubility retention rate is as follows: Take the supernatant after centrifugation, determine the polymer concentration in the supernatant by drying and weighing, and calculate it according to the following formula: Dissolution retention rate (%) = (polymer concentration in the supernatant after treatment / initial polymer concentration) × 100%.
[0061] Apparent viscosity was measured using a Brookfield viscometer at 25°C with an LV-4 (size 64) rotor at 60 rpm. Viscosity retention was calculated using the following formula: Viscosity retention rate (%) = (apparent viscosity of sample in electrolyte medium / apparent viscosity of sample in deionized water system of the same concentration) × 100%.
[0062] The stability test under continuous storage conditions was conducted as follows: The samples were placed in a specified ionic medium at 25°C for 48 hours or 7 days, and their appearance changes were observed. The insoluble matter rate and viscosity retention rate were also tested to evaluate their stability under continuous storage conditions. The test results are shown in Tables 1-3.
[0063] Table 1. Stability results in representative ionic media
[0064] As shown in Table 1, Example 1 maintains high transmittance and low insoluble content in the monovalent ion system, while in Ca... 2+ Mg 2+High transmittance and low precipitation levels were maintained in the coexisting system. Comparative Examples 1-5 showed significantly reduced transmittance and significantly increased insoluble matter content in the complex divalent ion system. This indicates that the synergistic presence of the first fixed cyclic quaternary ammonium cation side group and the second pyridinium carboxylic betaine ion side group is more conducive to maintaining the solubility and dispersion stability of the material in the composite electrolyte medium.
[0065] Table 2. Results of the comprehensive performance of hard water gradient when CaCl2 and MgCl2 coexist.
[0066] As can be seen from Table 2, with Ca 2+ / Mg 2+ With increasing coexisting hardness, all samples exhibited varying degrees of decreased transmittance, increased insoluble content, decreased solubility retention, and decreased viscosity retention. Specifically, Example 1 outperformed Comparative Examples 1-5 at all four hardness points, indicating that the synergistic introduction of dual side groups and the completion of hydrolysis of the second side group more effectively suppressed divalent ion-induced interchain association, precipitation, and rheological decay. Comparative Example 5, as a physical blend system, generally outperformed some results from samples with a single weaker side group, but was still significantly lower than Example 1, indicating that physical blending of a single side group sample alone cannot achieve the synergistic effect of two types of functional side groups on the same polymer chain. The results of Examples 2 and 4 were close to those of Example 1, demonstrating that within the scope defined by the claims, the lower limit or intermediate window can also achieve the desired effect. Example 3 was slightly inferior to Example 1 under high hardness conditions, indicating that excessively high reaction intensity or substitution levels may actually decrease overall performance.
[0067] Table 3 Ca 2+ and Mg 2+ Rheological preservation and sustained stability results in coexisting systems
[0068] As shown in Table 3, in the CaCl2 and MgCl2 coexisting system, Example 1 exhibits a higher viscosity retention rate, a lower 48-hour insoluble matter rate, and a higher 7-day viscosity retention rate, and after long-term storage, it only shows slight turbidity with no visible sedimentation. In contrast, Comparative Examples 1-5 are more prone to significant sedimentation, stratification, local flocculation, or viscosity decay. Although Comparative Example 5 is a physical blend system of a single-side-group sample, its sustained stability and rheological retention ability are still significantly lower than those of Example 1. This indicates that the present invention, by simultaneously introducing a first fixed cyclic quaternary ammonium cation side group and a second pyridinium carboxybetaine ion side group, and completing the hydrolytic transformation of the second side group, can effectively improve the sustained stability and rheological retention ability of the material in a composite divalent ionic medium.
[0069] As shown in Tables 1-3, the dual-ion side-group modified carboxymethyl cellulose obtained in Example 1 exhibits good solubility stability, low insoluble content, and high viscosity retention in different electrolyte media; especially in Ca... 2+ and Mg 2+ In the coexistence system, its overall performance is significantly better than that of unmodified carboxymethyl cellulose, samples containing only the first side group, samples containing only the second side group, samples that have not completed the hydrolysis and transformation of the second side group, and samples obtained by physical blending of two single-side group samples.
[0070] The comparative results show that the unmodified sample, the sample containing only the first side group, the sample containing only the second side group, the sample where the second side group has not been hydrolyzed and transformed, and the physical blend system of the two single side group samples all failed to reach the comprehensive performance level of Example 1. This indicates that the present invention, by synergistically introducing the first fixed cyclic quaternary ammonium cation side group and the second pyridinium carboxybetaine ion side group on the same carboxymethyl cellulose backbone and completing the hydrolysis and transformation of the second side group, is beneficial to improving the dissolution stability, continuous storage stability and rheological retention ability of the material in the composite divalent ionic medium.
[0071] Figure 2 and Figure 3 Example 1 and Comparative Examples 1, 2, 3 and 5 were selected as representative samples for graphical analysis.
[0072] like Figure 1 As shown, the preparation method of the present invention includes four steps: intermediate activation, introduction of a first fixed cyclic quaternary ammonium cation side group, grafting of a second side group precursor, and hydrolysis conversion.
[0073] like Figure 2 and Figure 3 As shown, in the hard water gradient system where CaCl2 and MgCl2 coexist, Example 1 exhibits a high viscosity retention rate and a low insoluble matter rate under different total hardness conditions.
[0074] like Figure 4 and Figure 5 As shown, in the CaCl2 and MgCl2 coexisting system, the transmittance and 7-day viscosity retention of Example 1 are both superior to those of the comparative examples.
[0075] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. All equivalent substitutions, modifications, or improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.
Claims
1. A method for preparing biionic side-group modified carboxymethyl cellulose, characterized in that, Includes the following steps: Step (1) Disperse sodium carboxymethyl cellulose in a mixed medium, add alkaline solution for alkalization and activation, and then add epichlorohydrin to react and obtain an intermediate containing a reactive chlorohydroxypropyl site; Step (2) Disperse the intermediate containing the reactive chlorohydroxypropyl site in a mixed medium, then add 1-methylpiperidine to react and introduce the first fixed cyclic quaternary ammonium cation side group to obtain the first ionic intermediate; Step (3) react methyl nicotinate with epichlorohydrin to obtain a reactive pyridinium intermediate, and then graft the reactive pyridinium intermediate with the first ionic intermediate to obtain an esterified intermediate; Step (4) The esterification intermediate is dispersed in an alcohol-water system, and an alkaline solution is added for hydrolysis to convert the second side group of the ester type into the second pyridinium carboxybetaine ion side group. After the reaction is completed, the mixture is neutralized, purified and dried to obtain the dual ion side group modified carboxymethyl cellulose.
2. The preparation method according to claim 1, characterized in that, In step (1), the mixing medium is a mixture of isopropanol and water in a volume ratio of 5:1 to 10:
1.
3. The preparation method according to claim 1, characterized in that, In step (1), the ratio of epichlorohydrin to sodium carboxymethyl cellulose is 0.2-1.0 mL:1 g; the alkali solution is a sodium hydroxide aqueous solution with a mass fraction of 5-20%; the reaction temperature is 25-45℃; and the reaction time is 2-8 h.
4. The preparation method according to claim 1, characterized in that, In step (2), the volume ratio of water to ethanol is 3:7 to 7:3; the mass ratio of 1-methylpiperidine to the intermediate containing the reactive chlorohydroxypropyl site is 0.2 to 1.2:
1.
5. The preparation method according to claim 1, characterized in that, In step (2), the reaction temperature is 50-80℃ and the reaction time is 4-12h. After the reaction, a dialysis bag or ultrafiltration membrane with a molecular weight cutoff of 5-20kDa is used for desalting and purification.
6. The preparation method according to claim 1, characterized in that, In step (3), methyl nicotinic acid reacts with epichlorohydrin in anhydrous acetonitrile, ethanol or a mixture thereof, at a reaction temperature of 55-65°C for 8-12 hours.
7. The preparation method according to claim 1, characterized in that, In step (3), the pH of the grafting reaction system is controlled at 8.0 to 10.5, the reaction temperature is 40 to 70°C, and the reaction time is 6 to 16 hours.
8. The preparation method according to claim 1, characterized in that, In step (4), the volume ratio of alcohol to water in the alcohol-water system is 1:3 to 3:1, and the alcohol is methanol or ethanol.
9. The preparation method according to claim 1, characterized in that, In step (4), the alkaline solution is a sodium hydroxide solution. After adding the alkaline solution, the pH of the system is controlled at 10.0 to 11.0, the reaction temperature is 35 to 45°C, and the reaction time is 4 to 8 hours. After the reaction is completed, the pH is adjusted to 6.5 to 7.5 with acid, and low molecular weight byproducts and inorganic salts are removed by dialysis, ultrafiltration or repeated alcohol washing.
10. A dual-ionic side-group modified carboxymethyl cellulose, characterized in that, The dual-ion modified carboxymethyl cellulose has a carboxymethyl cellulose backbone and contains a first fixed cyclic quaternary ammonium cation side group derived from 1-methylpiperidine and a second pyridinium carboxybetaine ion side group formed by the reaction and hydrolysis of methyl nicotinate. The modified carboxymethyl cellulose can be prepared by the method described in any one of claims 1-9.