Preparation method of high-viscosity sodium carboxymethyl cellulose

Abstract

The invention relates to the technical field of high polymer materials, in particular to high-viscosity sodium carboxymethyl cellulose. Comprising the following raw materials in parts by weight: 15-30 parts of a water-based acrylic resin emulsion, 8-20 parts of an organic pigment, 1-3 parts of modified corncob nanowhiskers, 1-3 parts of cerium-neodymium doped strontium tungstate nanosheets, 2-6 parts of a cyclodextrin hyperbranched emulsifier, 0.3-1 part of a pH buffer agent, 0.1-0.5 part of a flatting agent, 0.3-1 part of sodium polyacrylate and 0.1-0.2 part of a first auxiliary agent. According to the invention, hydrophobic groups are introduced to the surfaces of the modified corncob nanowhiskers through acetylation reaction, and the hydrophobic groups and carboxyl groups of the water-based acrylic resin form a dynamic hydrogen bond network, so that the problem that the storage stability and the printing leveling property of the ink are difficult to consider at the same time is solved, meanwhile, the dot expansion rate is effectively reduced, and the printing effect is improved.

Description

Technical Field

[0001] The invention relates to the technical field of polymer materials, in particular to a method for preparing high-viscosity sodium carboxymethyl cellulose. Background Art

[0002] Cellulose ether is a cellulose derivative obtained by chemically modifying natural cellulose. It is one of the most important water-soluble polymers in industry. It has thickening, dispersing, emulsifying, and bonding properties and is widely used in oil drilling, printing and dyeing textiles, papermaking, ceramics, food processing, and daily chemical industries.

[0003] Traditional sodium carboxymethyl cellulose uses a single etherification process, lacking a controllable cross-linking structure between molecular chains. This results in insufficient viscosity stability. During static storage, the molecular chains become disordered and entangled, easily forming localized high-viscosity regions. Under shear, the lack of reversible cross-linking points causes a sharp drop in viscosity. This uncontrollable rheological behavior performs poorly under complex operating conditions with alternating high and low shear rates. Based on this, the present invention provides a method for preparing high-viscosity sodium carboxymethyl cellulose. Summary of the Invention

[0004] The object of the present invention is to provide a method for preparing high-viscosity sodium carboxymethyl cellulose. The high-viscosity sodium carboxymethyl cellulose prepared by the present invention not only takes into account the requirements of fluidity and thickening performance, but also has good stability.

[0005] To achieve the above object, the present invention provides the following technical solution: a high-viscosity sodium carboxymethyl cellulose, comprising the following steps:

[0006] S1: preparing a pre-assembled mixture, wherein the raw materials of the pre-assembled mixture include cellulose pulp, sodium hydroxide aqueous solution, and ionic liquid modified montmorillonite;

[0007] S2: preparing a primary cross-linking solution, wherein the raw materials of the primary cross-linking solution include the pre-assembled mixture obtained in S1, sodium chloroacetate, and dialdehyde starch solution;

[0008] S3: preparing the ultimate cross-linked colloid, wherein the raw materials of the ultimate cross-linked colloid include the primary cross-linking liquid obtained in S2, a metal cross-linking agent, and a persimmon tannin extract;

[0009] S4: Freeze the ultimate cross-linked colloid at -20°C for 12 hours, then thaw at 25°C, repeating this cycle 3-5 times. The resulting product is dried to obtain high-viscosity sodium carboxymethyl cellulose.

[0010] Preferably, the preparation method of the ionic liquid modified montmorillonite is:

[0011] Step 1: Take calcium montmorillonite, add saturated sodium chloride solution at a solid-liquid ratio of 1:5, stir at 80°C for 3-4 hours, wash with water until there is no chloride ion, and then dry at 105°C to obtain the prepared material;

[0012] Step 2: a polyetheramine having a molecular weight of 1000 and chloroacetic acid are mixed in a molar ratio of 1:1.2 to obtain a mixture, the mixture is mixed with ethanol in a solid-liquid ratio of 1:5, and the mixture is refluxed at 70° C. for 6-7 hours to obtain a branched polyetheramine ionic liquid;

[0013] Step 3: The prepared material and the branched polyetheramine ionic liquid are mixed in a mass ratio of 10:1, stirred at 60° C. for 4-5 hours, centrifuged and filtered to obtain a precipitate, dried and crushed, and then passed through a 200-mesh sieve to obtain ionic liquid-modified montmorillonite.

[0014] Preferably, the preparation method of the pre-assembled mixture in S1 is: adding cellulose pulp and 30% by mass sodium hydroxide solution into a kneader, then adding ionic liquid modified montmorillonite, and stirring at a constant temperature of 60-70°C and 23-30rpm for 40-50min to obtain a pre-assembled mixture.

[0015] Preferably, the mass ratio of the cellulose pulp, sodium hydroxide solution and ionic liquid modified montmorillonite is (90-100):30:2, the polymerization degree of the cellulose pulp is ≥1500, the α-cellulose content is ≥95%, and the proportion of cellulose passing through an 80-mesh sieve is ≥80%.

[0016] Preferably, the preparation method of the dialdehyde starch solution in S2 is: corn starch and sodium periodate are mixed in water at a molar ratio of 1:1.2, reacted at a temperature of 35-45°C in the dark for 7-9 hours, and then the pH value is adjusted to 4.5 to prepare a 10wt% aqueous solution, which is the dialdehyde starch solution.

[0017] Preferably, the preparation method of the primary cross-linking liquid in S2 is: adding sodium chloroacetate to the pre-assembled mixture in 3-5 times, etherification reaction at 65-75°C for 80-90 minutes, washing the resulting product with a 20% ethanol solution with a mass fraction 3 times the mass of the product, and then adding 10 times the amount of deionized water to the resulting product for dissolution, then adjusting the pH to 7.5, and then adding dialdehyde starch solution, stirring at 40-45°C for 30-40 minutes to obtain a primary cross-linking liquid, wherein the mass ratio of the pre-assembled mixture, sodium chloroacetate, and dialdehyde starch solution is (20-30):7:2.

[0018] Preferably, the metal cross-linking agent is a mixed aqueous solution of ferric chloride and potassium ferrocyanide in a molar ratio of 1:2, wherein the concentration of ferric chloride is 0.25 mol / L and the concentration of potassium ferrocyanide is 0.5 mol / L.

[0019] Preferably, the preparation method of the persimmon tannin extract is: selecting fresh persimmon peel as raw material, air drying at 40-50°C for 7-8h, crushing and passing through a 20-mesh sieve to obtain dried persimmon peel powder, adding a 0.3% mass fraction of ascorbic acid aqueous solution at a solid-liquid ratio of 1:8, refluxing at 85°C for 2h under nitrogen protection to obtain a crude filtrate, filtering through a 0.45μm membrane and concentrating under reduced pressure to a solid content of ≥25% to obtain a concentrated solution, adding 0.1% pectinase by mass of the concentrated solution, and treating at 40°C and 25rpm for 1h to obtain a persimmon tannin extract.

[0020] Preferably, the preparation method of the ultimate cross-linked colloid in S3 is: adding a metal cross-linking agent to the primary cross-linking liquid at 2-3 ml / min, then letting it react for 20-30 minutes, then adding persimmon tannin extract, and stirring at a constant temperature of 45-55°C for 50-60 minutes to obtain the ultimate cross-linked colloid, wherein the mass ratio of the primary cross-linking liquid, the metal cross-linking agent, and the persimmon tannin extract is (80-100):2:3.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. In the present invention, a reversible cross-linked network is constructed by introducing dialdehyde starch and a metal cross-linking agent in stages. The aldehyde groups in the dialdehyde starch form dynamic covalent bonds with the hydroxyl groups on the cellulose molecular chains, maintaining moderate strength in the solution. This neither excessively restricts the movement of the molecular chains nor provides sufficient network support. This dynamic cross-linked network gives the product unique rheological properties, forming a high-strength network under static conditions and reversibly dissociating under shear, thereby enabling sodium carboxymethyl cellulose to meet the special requirements of different application scenarios for fluidity and thickening properties.

[0023] 2. In the present invention, the active ingredients in the persimmon tannin extract can form selective interactions with cellulose molecular chains, playing a molecular guiding role in the etherification reaction. By controlling the timing of adding the extract and the reaction conditions, the substitution position and degree of chloroacetic acid can be effectively regulated, so that the polyphenols in the extract produce hydrogen bonds with the cellulose molecules. This temporary binding can prevent local aggregation of the reaction reagents, promote the uniformity of the substitution reaction, and ensure the uniformity of the substitution.

[0024] 3. In the present invention, a polyetheramine ionic liquid is inserted into the interlayer of montmorillonite to form a composite with a nanoscale interlayer spacing. During the freeze-thaw process, the layered structure of the modified montmorillonite can effectively block the continuous growth of ice crystals and divide large-sized ice crystals into multiple tiny areas. At the same time, the grafted ionic liquid segments have good low-temperature flexibility and can buffer freezing stress. In addition, a step-by-step alkalization treatment with increasing temperature is used to ensure that the montmorillonite is fully dispersed, creating a uniform nano-reaction environment for the subsequent etherification reaction. As a result, the prepared sodium carboxymethyl cellulose exhibits excellent network structure stability during freeze-thaw cycles, solving the problem that traditional sodium carboxymethyl cellulose is prone to phase separation and performance degradation in low-temperature environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The invention provides a flow chart of a method for preparing high-viscosity sodium carboxymethyl cellulose. DETAILED DESCRIPTION

[0026] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0027] Example 1:

[0028] A high-viscosity sodium carboxymethyl cellulose comprises the following steps:

[0029] S1: preparing a pre-assembled mixture, wherein the raw materials of the pre-assembled mixture include cellulose pulp, sodium hydroxide aqueous solution, and ionic liquid modified montmorillonite;

[0030] S2: preparing a primary cross-linking solution, wherein the raw materials of the primary cross-linking solution include the pre-assembled mixture obtained in S1, sodium chloroacetate, and dialdehyde starch solution;

[0031] S3: preparing the ultimate cross-linked colloid, the raw materials of which include the primary cross-linking solution obtained in S2, a metal cross-linking agent, and a persimmon tannin extract;

[0032] S4: Freeze the ultimate cross-linked colloid at -20°C for 12 hours, then thaw at 25°C, repeating this cycle three times. The resulting product is dried to obtain high-viscosity sodium carboxymethyl cellulose.

[0033] The preparation method of ionic liquid modified montmorillonite is:

[0034] Step 1: Take calcium montmorillonite, add saturated sodium chloride solution at a solid-liquid ratio of 1:5, stir at 80°C for 3 hours, wash with water until there is no chloride ion, and then dry at 105°C to obtain the prepared material;

[0035] Step 2: A polyetheramine with a molecular weight of 1000 and chloroacetic acid are mixed in a molar ratio of 1:1.2 to obtain a mixture, the mixture is mixed with ethanol in a solid-liquid ratio of 1:5, and the mixture is refluxed at 70° C. for 6 hours to obtain a branched polyetheramine ionic liquid;

[0036] Step 3: The prepared material and the branched polyetheramine ionic liquid were mixed in a mass ratio of 10:1, stirred at 60° C. for 4 h, and the precipitate was obtained after centrifugal filtration. The precipitate was dried, crushed, and passed through a 200-mesh sieve to obtain ionic liquid-modified montmorillonite.

[0037] The preparation method of the pre-assembled mixture in S1 is as follows: cellulose pulp and 30% by mass sodium hydroxide solution are added into a kneader, and then ionic liquid modified montmorillonite is added, and the mixture is stirred at a constant temperature of 60° C. and 23 rpm for 40 minutes to obtain the pre-assembled mixture.

[0038] The mass ratio of cellulose pulp, sodium hydroxide solution and ionic liquid modified montmorillonite is 90:30:2, the polymerization degree of cellulose pulp is ≥1500, the α-cellulose content is ≥95%, and the proportion of cellulose passing through an 80-mesh sieve is ≥80%.

[0039] The preparation method of the dialdehyde starch solution in S2 is as follows: corn starch and sodium periodate are mixed in water at a molar ratio of 1:1.2, reacted at a temperature of 35°C in the dark for 7 hours, and then the pH value is adjusted to 4.5 to prepare a 10 wt% aqueous solution, which is the dialdehyde starch solution.

[0040] The preparation method of the primary cross-linking liquid in S2 is as follows: sodium chloroacetate is added to the pre-assembled mixture three times, etherification reaction is carried out at 65°C for 80 minutes, the resulting product is washed with a 20% ethanol solution with a mass fraction of 3 times the mass of the product, and then 10 times the amount of deionized water is added to the resulting product for dissolution, and then the pH is adjusted to 7.5, and then dialdehyde starch solution is added, and stirred at 40°C for 30 minutes to prepare the primary cross-linking liquid, wherein the mass ratio of the pre-assembled mixture, sodium chloroacetate, and dialdehyde starch solution is 20:7:2.

[0041] The metal cross-linking agent is a mixed aqueous solution of ferric chloride and potassium ferrocyanide in a molar ratio of 1:2, wherein the concentration of ferric chloride is 0.25 mol / L and the concentration of potassium ferrocyanide is 0.5 mol / L.

[0042] The preparation method of persimmon tannin extract is as follows: fresh persimmon peel is selected as raw material, air-dried at 40°C for 7 hours, crushed and sieved through a 20-mesh sieve to obtain dried persimmon peel powder, 0.3% by mass ascorbic acid aqueous solution is added at a solid-liquid ratio of 1:8, refluxed at 85°C for 2 hours under nitrogen protection to obtain a crude filtrate, filtered through a 0.45 μm membrane, and then concentrated under reduced pressure to a solid content of ≥25% to obtain a concentrated solution, pectinase is added at 0.1% by mass of the concentrated solution, and the solution is treated at 40°C and 25 rpm for 1 hour to obtain a persimmon tannin extract.

[0043] The preparation method of the ultimate cross-linked colloid in S3 is: add the metal cross-linking agent to the primary cross-linking liquid at 2 ml / min, then let it react for 20 minutes, then add the persimmon tannin extract, and stir at a constant temperature of 45°C for 50 minutes to obtain the ultimate cross-linked colloid, wherein the mass ratio of the primary cross-linking liquid, the metal cross-linking agent, and the persimmon tannin extract is 80:2:3.

[0044] Example 2:

[0045] A high-viscosity sodium carboxymethyl cellulose comprises the following steps:

[0046] S1: preparing a pre-assembled mixture, wherein the raw materials of the pre-assembled mixture include cellulose pulp, sodium hydroxide aqueous solution, and ionic liquid modified montmorillonite;

[0047] S2: preparing a primary cross-linking solution, wherein the raw materials of the primary cross-linking solution include the pre-assembled mixture obtained in S1, sodium chloroacetate, and dialdehyde starch solution;

[0048] S3: preparing the ultimate cross-linked colloid, the raw materials of which include the primary cross-linking solution obtained in S2, a metal cross-linking agent, and a persimmon tannin extract;

[0049] S4: Freeze the ultimate cross-linked colloid at -20°C for 12 hours, then thaw at 25°C, repeating the cycle four times. The resulting product is dried to obtain high-viscosity sodium carboxymethyl cellulose.

[0050] The preparation method of ionic liquid modified montmorillonite is:

[0051] Step 1: Take calcium montmorillonite, add saturated sodium chloride solution at a solid-liquid ratio of 1:5, stir at 80°C for 3.5h, wash with water until there is no chloride ion, and then dry at 105°C to obtain the prepared material;

[0052] Step 2: A polyetheramine with a molecular weight of 1000 and chloroacetic acid are mixed in a molar ratio of 1:1.2 to obtain a mixture, the mixture is mixed with ethanol in a solid-liquid ratio of 1:5, and the mixture is refluxed at 70° C. for 6.5 hours to obtain a branched polyetheramine ionic liquid;

[0053] Step 3: The prepared material and the branched polyetheramine ionic liquid were mixed in a mass ratio of 10:1, stirred at 60°C for 4.5 hours, and the precipitate was obtained after centrifugal filtration. The precipitate was dried and crushed and then passed through a 200-mesh sieve to obtain ionic liquid-modified montmorillonite.

[0054] The pre-assembled mixture in S1 is prepared by adding cellulose pulp and 30% by mass sodium hydroxide solution into a kneader, then adding ionic liquid modified montmorillonite, and stirring at a constant temperature of 65° C. and 26 rpm for 45 minutes to prepare the pre-assembled mixture.

[0055] The mass ratio of cellulose pulp, sodium hydroxide solution and ionic liquid modified montmorillonite is 95:30:2, the polymerization degree of cellulose pulp is ≥1500, the α-cellulose content is ≥95%, and the proportion of cellulose passing through an 80-mesh sieve is ≥80%.

[0056] The preparation method of the dialdehyde starch solution in S2 is as follows: corn starch and sodium periodate are mixed in water at a molar ratio of 1:1.2, reacted at 40°C in the dark for 7-9 hours, and then the pH value is adjusted to 4.5 to prepare a 10 wt% aqueous solution, which is the dialdehyde starch solution.

[0057] The preparation method of the primary cross-linking liquid in S2 is as follows: sodium chloroacetate is added to the pre-assembled mixture in 4 times, etherification reaction is carried out at 70°C for 85 minutes, the obtained product is washed with a 20% ethanol solution with a mass fraction of 3 times the mass of the product, and then 10 times the amount of deionized water is added to the obtained product for dissolution, and then the pH is adjusted to 7.5, and then dialdehyde starch solution is added, and stirred at 43°C for 35 minutes to obtain a primary cross-linking liquid, wherein the mass ratio of the pre-assembled mixture, sodium chloroacetate, and dialdehyde starch solution is 25:7:2.

[0058] The metal cross-linking agent is a mixed aqueous solution of ferric chloride and potassium ferrocyanide in a molar ratio of 1:2, wherein the concentration of ferric chloride is 0.25 mol / L and the concentration of potassium ferrocyanide is 0.5 mol / L.

[0059] The preparation method of persimmon tannin extract is as follows: fresh persimmon peel is selected as raw material, air-dried at 48°C for 7.5 hours, crushed and sieved through a 20-mesh sieve to obtain dried persimmon peel powder, 0.3% by mass ascorbic acid aqueous solution is added at a solid-liquid ratio of 1:8, refluxed at 85°C for 2 hours under nitrogen protection to obtain a crude filtrate, filtered through a 0.45μm membrane, and then concentrated under reduced pressure to a solid content of ≥25% to obtain a concentrated solution, 0.1% pectinase by mass of the concentrated solution is added, and the solution is treated at 40°C and 25rpm for 1 hour to obtain a persimmon tannin extract.

[0060] The preparation method of the ultimate cross-linked colloid in S3 is: add the metal cross-linking agent to the primary cross-linking liquid at 2.5 ml / min, then let it react for 25 minutes, then add the persimmon tannin extract, and stir at a constant temperature of 50°C for 55 minutes to obtain the ultimate cross-linked colloid, wherein the mass ratio of the primary cross-linking liquid, the metal cross-linking agent, and the persimmon tannin extract is 90:2:3.

[0061] Example 3:

[0062] A high-viscosity sodium carboxymethyl cellulose comprises the following steps:

[0063] S1: preparing a pre-assembled mixture, wherein the raw materials of the pre-assembled mixture include cellulose pulp, sodium hydroxide aqueous solution, and ionic liquid modified montmorillonite;

[0064] S2: preparing a primary cross-linking solution, wherein the raw materials of the primary cross-linking solution include the pre-assembled mixture obtained in S1, sodium chloroacetate, and dialdehyde starch solution;

[0065] S3: preparing the ultimate cross-linked colloid, the raw materials of which include the primary cross-linking solution obtained in S2, a metal cross-linking agent, and a persimmon tannin extract;

[0066] S4: Freeze the ultimate cross-linked colloid at -20°C for 12 hours, then thaw at 25°C, repeating this cycle five times. The resulting product is dried to obtain high-viscosity sodium carboxymethyl cellulose.

[0067] The preparation method of ionic liquid modified montmorillonite is:

[0068] Step 1: Take calcium montmorillonite, add saturated sodium chloride solution at a solid-liquid ratio of 1:5, stir at 80°C for 4 hours, wash with water until there is no chloride ion, and then dry at 105°C to obtain the prepared material;

[0069] Step 2: A polyetheramine with a molecular weight of 1000 and chloroacetic acid are mixed in a molar ratio of 1:1.2 to obtain a mixture, the mixture is mixed with ethanol in a solid-liquid ratio of 1:5, and the mixture is refluxed at 70° C. for 7 hours to obtain a branched polyetheramine ionic liquid;

[0070] Step 3: The prepared material and the branched polyetheramine ionic liquid were mixed in a mass ratio of 10:1, stirred at 60°C for 5 hours, centrifuged and filtered to obtain a precipitate, dried and crushed, and then passed through a 200-mesh sieve to obtain an ionic liquid-modified montmorillonite.

[0071] The preparation method of the pre-assembled mixture in S1 is as follows: cellulose pulp and 30% by mass sodium hydroxide solution are added into a kneader, and then ionic liquid modified montmorillonite is added, and the mixture is stirred at a constant temperature of 70° C. and 30 rpm for 50 minutes to obtain the pre-assembled mixture.

[0072] The mass ratio of cellulose pulp, sodium hydroxide solution and ionic liquid modified montmorillonite is 100:30:2, the polymerization degree of cellulose pulp is ≥1500, the α-cellulose content is ≥95%, and the proportion of cellulose passing through an 80-mesh sieve is ≥80%.

[0073] The preparation method of the dialdehyde starch solution in S2 is as follows: corn starch and sodium periodate are mixed in water at a molar ratio of 1:1.2, reacted at a temperature of 45°C in the dark for 9 hours, and then the pH value is adjusted to 4.5 to prepare a 10 wt% aqueous solution, which is the dialdehyde starch solution.

[0074] The preparation method of the primary cross-linking liquid in S2 is as follows: sodium chloroacetate is added to the pre-assembled mixture in 5 times, etherification reaction is carried out at 75°C for 90 minutes, the resulting product is washed with a 20% ethanol solution with a mass fraction 3 times the mass of the product, and then 10 times the amount of deionized water is added to the resulting product for dissolution, and then the pH is adjusted to 7.5, and then dialdehyde starch solution is added, and stirred at 45°C for 40 minutes to obtain a primary cross-linking liquid, wherein the mass ratio of the pre-assembled mixture, sodium chloroacetate, and dialdehyde starch solution is 30:7:2.

[0075] The metal cross-linking agent is a mixed aqueous solution of ferric chloride and potassium ferrocyanide in a molar ratio of 1:2, wherein the concentration of ferric chloride is 0.25 mol / L and the concentration of potassium ferrocyanide is 0.5 mol / L.

[0076] The preparation method of persimmon tannin extract is as follows: fresh persimmon peel is selected as raw material, air-dried at 50°C for 8 hours, crushed and sieved through a 20-mesh sieve to obtain dried persimmon peel powder, 0.3% by mass ascorbic acid aqueous solution is added at a solid-liquid ratio of 1:8, refluxed at 85°C for 2 hours under nitrogen protection to obtain a crude filtrate, filtered through a 0.45μm membrane, and then concentrated under reduced pressure to a solid content of ≥25% to obtain a concentrated solution, pectinase is added at 0.1% by mass of the concentrated solution, and the solution is treated at 40°C and 25rpm for 1 hour to obtain a persimmon tannin extract.

[0077] The preparation method of the ultimate cross-linked colloid in S3 is: add the metal cross-linking agent to the primary cross-linking liquid at 3 ml / min, then let it react for 30 minutes, then add the persimmon tannin extract, and stir at a constant temperature of 55°C for 60 minutes to obtain the ultimate cross-linked colloid, wherein the mass ratio of the primary cross-linking liquid, the metal cross-linking agent, and the persimmon tannin extract is 100:2:3.

[0078] Comparative Example 1: The difference between this comparative example and Example 1 is that an equal amount of ordinary sodium-montmorillonite is used in this comparative example to replace the ionic liquid-modified montmorillonite.

[0079] Comparative Example 2: This comparative example differs from Example 1 in that no dialdehyde starch solution is added in this comparative example.

[0080] Comparative Example 3: This comparative example differs from Example 1 in that an equal amount of pure water is used in this comparative example instead of the persimmon tannin extract.

[0081] Performance test: The high viscosity sodium carboxymethyl cellulose prepared in Examples 1-3 and Comparative Examples 1-3 was subjected to performance tests, and the test data obtained are recorded in the following table:

[0082]

[0083]

[0084] In the performance test, the sodium carboxymethyl cellulose prepared in Examples 1-3 and Comparative Examples 1-3, Example 1, Example 2, Example 3, Comparative Example 1, Comparative Example 2, Comparative Example 3 and Comparative Example 4 were tested, respectively. The viscosity test was based on the GB / T29596-2013 standard, the freeze-thaw stability test was based on the GB / T41931-2022 standard, and the uniformity test was replaced by infrared spectroscopy.

[0085] By comparing the data in the table, it can be seen that the high viscosity sodium carboxymethyl cellulose prepared in Examples 1-3 has better performance than the high viscosity sodium carboxymethyl cellulose prepared in Comparative Examples 1-3 in all test performances;

[0086] This shows that by introducing dialdehyde starch and metal crosslinkers in stages, a reversible crosslinked network is constructed. The aldehyde groups in the dialdehyde starch form dynamic covalent bonds with the hydroxyl groups on the cellulose molecular chains, maintaining moderate strength in solution. This neither excessively restricts the movement of the molecular chains nor provides sufficient network support. This dynamic crosslinked network gives the product unique rheological properties, forming a high-strength network under static conditions and reversibly dissociating under shear, allowing sodium carboxymethyl cellulose to meet the special requirements of different application scenarios for fluidity and thickening properties.

[0087] The active ingredients in the persimmon tannin extract can selectively interact with cellulose molecular chains, acting as molecular guides in the etherification reaction. By controlling the timing of extract addition and reaction conditions, the position and degree of chloroacetic acid substitution can be effectively regulated, allowing the polyphenols in the extract to form hydrogen bonds with the cellulose molecules. This temporary bond prevents localized aggregation of the reactants, promotes uniform substitution, and ensures uniform substitution.

[0088] By inserting polyetheramine ionic liquid into the interlayers of montmorillonite, a composite with nano-scale interlayer spacing is formed. During the freeze-thaw process, the layered structure of this modified montmorillonite can effectively block the continuous growth of ice crystals and divide large-sized ice crystals into multiple tiny areas. At the same time, the grafted ionic liquid chain segments have good low-temperature flexibility and can buffer freezing stress. The step-by-step alkalization treatment is used to ensure that the montmorillonite is fully dispersed, creating a uniform nano-reaction environment for the subsequent etherification reaction. The prepared sodium carboxymethyl cellulose exhibits excellent network structure stability during the freeze-thaw cycle, solving the problem that traditional sodium carboxymethyl cellulose is prone to phase separation and performance degradation in low-temperature environments.

[0089] By comparing and analyzing the relevant data in the table, it can be seen that the high-viscosity sodium carboxymethyl cellulose prepared by the present invention not only takes into account the requirements of fluidity and thickening performance, but also has good stability. This shows that the high-viscosity sodium carboxymethyl cellulose provided by the present invention has a broader market prospect and is more suitable for promotion.

[0090] Throughout this specification, references to terms such as "one embodiment," "example," or "specific example" indicate that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0091] The preferred embodiments of the present invention disclosed above are intended only to help illustrate the present invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the present invention to the specific embodiments described. Obviously, many modifications and variations are possible based on the content of this specification. These embodiments are selected and described in detail in this specification to better explain the principles and practical applications of the present invention, thereby enabling those skilled in the art to better understand and utilize the present invention. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A high viscosity sodium carboxymethyl cellulose, characterized in that The following steps are involved: S1: preparing a pre-assembled mixture, wherein the raw materials of the pre-assembled mixture include cellulose pulp, sodium hydroxide aqueous solution, and ionic liquid modified montmorillonite; S2: preparing a primary cross-linking solution, wherein the raw materials of the primary cross-linking solution include the pre-assembled mixture obtained in S1, sodium chloroacetate, and dialdehyde starch solution; S3: preparing the ultimate cross-linked colloid, wherein the raw materials of the ultimate cross-linked colloid include the primary cross-linking liquid obtained in S2, a metal cross-linking agent, and a persimmon tannin extract; S4: Freeze the ultimate cross-linked colloid at -20°C for 12 hours, then thaw at 25°C, repeating this cycle 3-5 times. The resulting product is dried to obtain high-viscosity sodium carboxymethyl cellulose.

2. The high viscosity sodium carboxymethyl cellulose according to claim 1, characterized in that The preparation method of the ionic liquid modified montmorillonite is: Step 1: Take calcium montmorillonite, add saturated sodium chloride solution at a solid-liquid ratio of 1:5, stir at 80°C for 3-4 hours, wash with water until there is no chloride ion, and then dry at 105°C to obtain the prepared material; Step 2: a polyetheramine having a molecular weight of 1000 and chloroacetic acid are mixed in a molar ratio of 1:1.2 to obtain a mixture, the mixture is mixed with ethanol in a solid-liquid ratio of 1:5, and the mixture is refluxed at 70° C. for 6-7 hours to obtain a branched polyetheramine ionic liquid; Step 3: The prepared material and the branched polyetheramine ionic liquid are mixed in a mass ratio of 10:1, stirred at 60° C. for 4-5 hours, centrifuged and filtered to obtain a precipitate, dried and crushed, and then passed through a 200-mesh sieve to obtain ionic liquid-modified montmorillonite.

3. The high viscosity sodium carboxymethyl cellulose according to claim 2, characterized in that The preparation method of the pre-assembled mixture in S1 is as follows: cellulose pulp and 30% by mass sodium hydroxide solution are added into a kneader, and then ionic liquid modified montmorillonite is added, and the mixture is stirred at a constant temperature of 60-70° C. and 23-30 rpm for 40-50 minutes to obtain the pre-assembled mixture.

4. The high viscosity sodium carboxymethyl cellulose according to claim 3, characterized in that The mass ratio of the cellulose pulp, sodium hydroxide solution and ionic liquid modified montmorillonite is (90-100):30:

2. The polymerization degree of the cellulose pulp is ≥1500, the α-cellulose content is ≥95%, and the proportion of cellulose passing through an 80-mesh sieve is ≥80%.

5. The high viscosity sodium carboxymethyl cellulose according to claim 1, characterized in that The dialdehyde starch solution in S2 is prepared by mixing corn starch and sodium periodate in a molar ratio of 1:1.2 in water, reacting at a temperature of 35-45° C. in the dark for 7-9 hours, and then adjusting the pH value to 4.5 to prepare a 10 wt % aqueous solution, which is the dialdehyde starch solution.

6. The high viscosity sodium carboxymethyl cellulose according to claim 5, characterized in that The preparation method of the primary cross-linking liquid in S2 is as follows: sodium chloroacetate is added to the pre-assembled mixture in 3-5 times, etherification reaction is carried out at 65-75°C for 80-90 minutes, the resulting product is washed with a 20% ethanol solution with a mass fraction 3 times the mass of the product, and then 10 times the amount of deionized water is added to the resulting product for dissolution, and then the pH is adjusted to 7.5, and then a dialdehyde starch solution is added, and stirred at 40-45°C for 30-40 minutes to obtain a primary cross-linking liquid, wherein the mass ratio of the pre-assembled mixture, sodium chloroacetate, and dialdehyde starch solution is (20-30):7:

2.

7. The high viscosity sodium carboxymethyl cellulose according to claim 1, characterized in that The metal cross-linking agent is a mixed aqueous solution of ferric chloride and potassium ferrocyanide in a molar ratio of 1:2, wherein the concentration of ferric chloride is 0.25 mol / L and the concentration of potassium ferrocyanide is 0.5 mol / L.

8. The high viscosity sodium carboxymethyl cellulose according to claim 1, characterized in that The preparation method of the persimmon tannin extract comprises the following steps: selecting fresh persimmon peel as a raw material, drying with forced air at 40-50° C. for 7-8 hours, crushing and filtering through a 20-mesh sieve to obtain dried persimmon peel powder, adding a 0.3% by mass ascorbic acid aqueous solution at a solid-liquid ratio of 1:8, refluxing at 85° C. for 2 hours under nitrogen protection to obtain a crude filtrate, filtering through a 0.45 μm membrane, and concentrating under reduced pressure to a solid content of ≥25% to obtain a concentrated solution, adding pectinase in an amount of 0.1% by mass of the concentrated solution, and treating at 40° C. and 25 rpm for 1 hour to obtain the persimmon tannin extract.

9. The high viscosity sodium carboxymethyl cellulose according to claim 8, characterized in that The preparation method of the ultimate cross-linked colloid in S3 is: adding a metal cross-linking agent to the primary cross-linking liquid at 2-3 ml / min, then standing to react for 20-30 minutes, then adding persimmon tannin extract, and stirring at a constant temperature of 45-55°C for 50-60 minutes to obtain the ultimate cross-linked colloid, wherein the mass ratio of the primary cross-linking liquid, the metal cross-linking agent, and the persimmon tannin extract is (80-100):2:

3.

10. A high viscosity sodium carboxymethyl cellulose, characterized in that The high-viscosity sodium carboxymethyl cellulose is prepared by the preparation method of any one of claims 1 to 9.

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