A cellulose solution containing a stabilizer, and a method for preparing and using the same

Abstract

The application discloses a cellulose solution containing a stabilizer and a preparation method and application thereof, and the preparation method comprises the following steps: stirring and mixing an ionic liquid and a stabilizer at room temperature until a uniform mixture is obtained; adding a cellulose raw material into the obtained mixture, fully stirring and pre-mixing at room temperature to form a pre-dissolved cellulose mixture; and heating and stirring the obtained cellulose mixture until the cellulose raw material is completely dissolved to form a uniform and transparent cellulose solution, that is, the cellulose solution containing the stabilizer is obtained. By adding the stabilizer, the application reduces the color deepening of the ionic liquid in the process of dissolving the cellulose under high temperature or water-containing conditions.

Description

Technical Field

[0001] This invention relates to a cellulose solution containing a stabilizer, its preparation method, and its application, belonging to the field of green chemistry and cellulose dissolution and processing technology. Background Technology

[0002] Cellulose is one of the most abundant natural polymers on Earth, widely found in plant cell walls. It consists of glucose units linked by β-1,4-glycosidic bonds, with numerous intramolecular and intermolecular hydrogen bond networks, resulting in a complex aggregate structure that makes the polymer chains difficult to slide and separate. Therefore, it is difficult to dissolve in conventional solvents and cannot be melt-processed, increasing the difficulty of its processing and applications. Existing industrial dissolution technologies include the viscose process and the lyocell process. The viscose process uses natural cellulose (such as wood, cotton linters, etc.) as raw material, which is alkalized and derivatized with carbon disulfide to produce cellulose xanthate, which is then dissolved and processed into films or filaments. This process requires the use of large amounts of strong acids and bases, and the finished product is prone to porosity and grooves. The lyocell process uses N-methylmorpholine-N-oxide (NMMO) solvent to physically dissolve cellulose, followed by dry-jet wet spinning to prepare regenerated cellulose filaments. This process has high equipment requirements, and the NMMO used has a cyclic ether structure, which easily triggers thermal runaway reactions, posing significant safety risks. Stabilizers such as propyl gallate are needed to control the reaction.

[0003] In recent years, ionic liquids (ILs), as a green solvent, have been regarded as a potential alternative to traditional cellulose solvents due to their low volatility, good solubility, and tunable structural properties. There is a rich variety of ILs, including imidazole, pyridine, quaternary ammonium salts, quaternary phosphonium salts, and superbasic ILs. Different types of ILs exhibit different advantages in cellulose dissolution, and their solubility can be further optimized by adjusting the structure of their cations and anions. Imidazole and pyridine ILs are widely used in cellulose dissolution processing due to their strong polarity and hydrogen bond breaking ability; quaternary ammonium salts and quaternary phosphonium salts have advantages in room-temperature homogeneous cellulose processing applications due to their mild reactivity; and superbasic ILs, due to their simple synthesis, non-corrosiveness, and extremely high cellulose dissolution capacity, show great promise in industrial spinning and film production applications. However, despite the significant advantages of solvents (ILs) in cellulose dissolution, all ILs capable of dissolving cellulose generally face degradation problems, especially under high temperature or high humidity environments. The active cations in ILs (such as imidazole, pyridinium, amidines, and guanidines) are prone to hydrolysis, oxidation, and other degradation reactions. These reactions lead to a darkening of the IL's color, deactivation of functional groups, and the potential generation of corrosive byproducts, thus affecting its solubility and limiting its continued application in cellulose dissolution. Furthermore, IL recycling technologies are still underdeveloped. If the degradation problems encountered during recycling cannot be effectively addressed, not only will its solubility be affected, but impurities may also be introduced, impacting the quality of subsequent cellulose conversion products and even creating new environmental burdens after large-scale use.

[0004] Therefore, inhibiting the degradation of cellulose leaching materials (ILs) is crucial for industrial production. This not only determines whether ILs can stably dissolve cellulose but also relates to their feasibility in large-scale industrial applications. Currently, stabilizer research mainly focuses on metal salts (such as lead salts and calcium-zinc salts) and polymer coatings (such as nylon and silica coatings). These methods are widely used in polymer processing, coatings, rubber, packaging, and metal corrosion protection, inhibiting material degradation at high temperatures through physical barriers or chemical interactions. However, research on dedicated stabilizers for IL degradation caused by high temperature or high humidity remains insufficient, severely restricting the practical application of ILs. Therefore, developing a general-purpose stabilizer, especially one that effectively prevents IL degradation under high temperature and high humidity conditions, is particularly important. In-depth research into the degradation characteristics of ILs and the development of corresponding stabilizers will provide key support for optimizing existing production processes, helping to overcome industrial bottlenecks, promoting the large-scale and high-quality production of cellulose-related products, thereby enhancing industrial competitiveness and promoting the economic development of the cellulose industry. In particular, developing a low-cost, environmentally friendly, and highly effective stabilizer to improve the stability of ILs has significant practical implications. This not only reduces the accumulation of solvent degradation waste and potential pollution, but also reduces the environmental burden of production, ensures the green properties of cellulose materials, conforms to the trend of sustainable development, and contributes to ecological and environmental protection. Summary of the Invention

[0005] In view of this, the main objective of the present invention is to provide a cellulose solution containing a stabilizer, a method for preparing the solution and its application. The technical problem to be solved is to reduce the color deepening of ILs during the dissolution of cellulose under high temperature or aqueous conditions by adding a stabilizer.

[0006] The objective of this invention and the technical problem it solves are achieved by the following technical solution. A method for preparing a cellulose solution containing a stabilizer according to this invention includes the following steps:

[0007] S1 involves stirring the ionic liquid and stabilizer at room temperature until a homogeneous mixture is obtained;

[0008] S2. Add cellulose raw material to the mixture obtained in step S1, stir and premix thoroughly at room temperature to form a pre-dissolved cellulose mixture;

[0009] S3. The cellulose mixture obtained in step S2 is heated and stirred until the cellulose raw material is completely dissolved to form a uniform and transparent cellulose solution, which is the cellulose solution containing the stabilizer.

[0010] The objectives of this invention and the technical problems solved can be further achieved by the following technical measures.

[0011] Preferably, in the aforementioned method for preparing a cellulose solution containing a stabilizer, in step S1, the ionic liquid is selected from at least one of imidazole ionic liquids, pyridine ionic liquids, quaternary ammonium salt ionic liquids, quaternary phosphonium salt ionic liquids, and superbasic ionic liquids.

[0012] Preferably, in the aforementioned method for preparing a cellulose solution containing a stabilizer, in step S1, the water content of the ionic liquid ranges from 0% to 30%.

[0013] Preferably, in the aforementioned method for preparing a cellulose solution containing a stabilizer, in step S1, the cellulose is dissolved at a temperature of 100–150 °C, rotated at a speed of 100–300 rpm, and subjected to a vacuum of 20–60 bar; the mass percentage concentration of the homogeneous cellulose solution is 2%–14%.

[0014] Preferably, in the aforementioned method for preparing a cellulose solution containing a stabilizer, in step S1, the stabilizer is selected from one of phenols, phosphate esters, organic acids and their salts, sulfites, amino compounds, metal complexes, organotin compounds, plant extracts, and esters.

[0015] Preferably, in the aforementioned method for preparing a cellulose solution containing a stabilizer, in step S1, the phenol is selected from one of butylated hydroxytoluene, tert-butylhydroquinone, butylated hydroxyanisole, butylated hydroxyanisole, ethyl gallate, and probucol.

[0016] Preferably, in the aforementioned method for preparing a cellulose solution containing a stabilizer, in step S1, the phosphate ester is selected from one of triethyl phosphite, tris(2,4-di-tert-butylphenyl) phosphite, phosphite, tris(2,4-di-tert-butylphenyl) phosphate, and di(2-ethylhexyl) phosphite.

[0017] Preferably, in the aforementioned method for preparing a cellulose solution containing a stabilizer, in step S1, the organic acid and its salts are selected from one of sodium citrate, malic acid, calcium pantothenate, ascorbic acid, sodium ascorbate, calcium ascorbate, potassium ascorbate, sodium lactate, calcium lactate, potassium lactate, fumaric acid, and potassium tartrate.

[0018] Preferably, in the aforementioned method for preparing a cellulose solution containing a stabilizer, in step S1, the sulfite is selected from one of sodium bisulfite, sodium thiosulfate, sodium metabisulfite, sodium hydrosulfite, calcium sulfite, and sodium hydrocyanate.

[0019] Preferably, in the aforementioned method for preparing a cellulose solution containing a stabilizer, in step S1, the amino compound is selected from one of N-acetylcysteine, 30% hydroxylamine, mecobalamin, hydroxylamine hydrochloride, hydroxylamine sulfate, hydroxylamine nitrate, and sodium diethyldithiocarbamate.

[0020] Preferably, in the aforementioned method for preparing a cellulose solution containing a stabilizer, in step S1, the metal complex is selected from one of disodium edetate, ethylenediaminetetraacetate, ferrous chloride, and iron-manganese complex.

[0021] Preferably, in the aforementioned method for preparing a cellulose solution containing a stabilizer, in step S1, the organotin compound is selected from one of dibutyltin cinnamate, isooctyltin, and diethyldibutyltin.

[0022] Preferably, in the aforementioned method for preparing a cellulose solution containing a stabilizer, in step S1, the plant extract is selected from one of chlorogenic acid, proanthocyanidins, tocopherol, resveratrol, and olive leaf extract.

[0023] Preferably, in the aforementioned method for preparing a cellulose solution containing a stabilizer, in step S1, the ester is selected from one of polyethylene glycol succinate, ascorbate palmitate, tocopheryl palmitate, stearate antioxidants, and isophorone diester.

[0024] Preferably, in the aforementioned method for preparing a cellulose solution containing a stabilizer, in step S1, the concentration of the stabilizer ranges from 0.01% to 5% of the total mass of the ionic liquid.

[0025] Preferably, in the aforementioned method for preparing a cellulose solution containing a stabilizer, in step S2, the cellulose raw material is selected from at least one of microcrystalline cellulose, wood dissolving pulp, cotton pulp, wheat straw dissolving pulp, reed dissolving pulp, straw dissolving pulp, moso bamboo dissolving pulp, bamboo dissolving pulp, mian bamboo dissolving pulp, and hard-headed yellow bamboo dissolving pulp.

[0026] Preferably, in the aforementioned method for preparing a cellulose solution containing a stabilizer, in step S2, the degree of polymerization (DP) of the cellulose ranges from 100 to 1200.

[0027] Preferably, in the aforementioned method for preparing a cellulose solution containing a stabilizer, in step S2, the amount of cellulose raw material added is 2% to 14% of the total mass of the ionic liquid.

[0028] Preferably, in the aforementioned method for preparing a cellulose solution containing a stabilizer, in step S2, the premixing conditions of the cellulose raw material are carried out at room temperature and pressure, and the premixing speed is 200 rpm.

[0029] Preferably, in the aforementioned method for preparing a cellulose solution containing a stabilizer, in step S3, the heating conditions of the cellulose raw material are in the range of 100 ℃ to 150 ℃.

[0030] The objective of this invention and the technical problem it solves are achieved by the following technical solution. According to this invention, a cellulose solution containing a stabilizer is provided, which is prepared by the method described above.

[0031] The objective of this invention and the technical problem it solves are achieved by the following technical solution: The application of a cellulose solution containing a stabilizer in the preparation of regenerated cellulose films, according to this invention.

[0032] The objectives of this invention and the technical problems solved can be further achieved by the following technical measures.

[0033] Preferably, the application of the aforementioned cellulose solution containing a stabilizer in the preparation of regenerated cellulose films includes the following steps:

[0034] a. A cellulose solution is coated onto a glass substrate using a doctor blade, and then placed in a vacuum environment for degassing and leveling to form a thin film;

[0035] b. Immerse the coated glass plate in a coagulation bath, and after it is completely regenerated, remove it, rinse it with deionized water, and dry it in the air to form a film.

[0036] Preferably, in the application of the aforementioned cellulose solution containing stabilizer in the preparation of regenerated cellulose film, the coating thickness in step a is 0.25–0.80 mm.

[0037] Preferably, in the application of the aforementioned cellulose solution containing stabilizers in the preparation of regenerated cellulose films, in step b, the coagulation bath is selected from one of deionized water, anhydrous ethanol, methanol, isopropanol, dimethyl sulfoxide, acetone, acetic acid, and methoxyacetic acid, and the soaking time of the coagulation bath is 5 to 30 minutes.

[0038] The objective of this invention and the technical problem it solves are achieved by the following technical solution: The application of a cellulose solution containing a stabilizer in the preparation of regenerated cellulose fibers, according to this invention.

[0039] The objectives of this invention and the technical problems solved can be further achieved by the following technical measures.

[0040] Preferably, the application of the aforementioned cellulose solution containing a stabilizer in the preparation of regenerated cellulose fibers includes the following steps:

[0041] c. The cellulose solution is extruded into a coagulation bath at 80 °C via wet spinning or dry-jet wet spinning, and wet fibers are obtained through solvent exchange.

[0042] d. Place the wet fiber obtained in step c in a coagulation bath and let it stand for more than 24 hours, or repeatedly wind and move it through the coagulation bath to allow the wet fiber to fully exchange solvent with the solvent in the coagulation bath. Then, continuously dry or intermittently dry in an oven to obtain regenerated cellulose fiber.

[0043] Preferably, in the application of the aforementioned cellulose solution containing stabilizer in the preparation of regenerated cellulose fibers, in step c, the spinning needle used in the wet spinning or dry-jet wet spinning is one of 10G to 32G; the extrusion speed is 0.05 to 0.5 mL / min; and the extrusion temperature is 25 to 120℃.

[0044] Preferably, in the application of the aforementioned cellulose solution containing stabilizers in the preparation of regenerated cellulose fibers, in step d, the coagulation bath is selected from one of deionized water, anhydrous ethanol, methanol, isopropanol, dimethyl sulfoxide, acetone, acetic acid, and methoxyacetic acid.

[0045] Compared with existing technologies, the cellulose solution containing a stabilizer, its preparation method, and its application described in this invention have the following beneficial effects:

[0046] This invention involves mixing solvents (ILs) with different water contents and a stabilizer at room temperature with continuous stirring. Cellulose raw material is then added, and the mixture is heated to a specific temperature to obtain a uniform and transparent cellulose solution. Experiments showed that the cellulose solution with a small amount of stabilizer added was lighter in color than the solution without stabilizer, and this did not negatively affect the cellulose's solubility or trigger any side reactions. Further analysis indicated that no stabilizer residue was found in the resulting regenerated cellulose film or fiber. In summary, the method proposed in this invention is simple, effectively inhibits the degradation of ILs, prevents color deepening, significantly improves production efficiency, reduces capital investment, and achieves a dual optimization of efficiency and economy.

[0047] This invention effectively improves the stability of cellulose-soluble solvents (ILs) under high temperature or high water content conditions by adding a stabilizer during the cellulose dissolution process. This inhibits decomposition reactions, prevents color deepening, significantly reduces the formation of degradation byproducts, and improves the recycling efficiency of ILs. The stabilizer described in this invention is applicable to various ILs capable of dissolving cellulose, meeting the needs of industrial applications. It is mainly used in the preparation of regenerated cellulose membranes, filaments, granules, and other materials. Its advantages include being environmentally friendly, having a simple process, controllable cost, and aligning with sustainable development principles.

[0048] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the preferred embodiments of the present invention are described in detail below. Attached Figure Description

[0049] Figure 1 This is a graph showing the color changes of the cellulose solution obtained after degradation at different temperatures according to the present invention.

[0050] Figure 2 The ultraviolet spectra of the cellulose solutions obtained after degradation at different temperatures according to the present invention are shown.

[0051] Figure 3 The rheological properties of cellulose solutions obtained after degradation at different temperatures according to the present invention;

[0052] Figure 4 This is a color comparison diagram of the cellulose solution before and after the addition of the stabilizer in this invention.

[0053] Figure 5 CIE diagrams (International Commission on Illumination) of cellulose solutions before and after the addition of stabilizers according to this invention;

[0054] Figure 6 The tensile strength of the regenerated cellulose film prepared at a dissolution temperature of 130 °C before and after the addition of the stabilizer in this invention;

[0055] Figure 7 Comparison of the appearance of fibers after being soaked in a coagulation bath for the same time and dried before and after the addition of the stabilizer according to the present invention;

[0056] Figure 8 The infrared spectra of the regenerated cellulose fibers prepared at a dissolution temperature of 130 °C before and after the addition of the stabilizer are shown in this invention. Detailed Implementation

[0057] To further illustrate the technical means and effects adopted by the present invention to achieve its intended purpose, the following detailed description, in conjunction with preferred embodiments, provides a detailed explanation of the specific implementation methods, structures, features, and effects of a cellulose solution containing a stabilizer, its preparation method, and its application according to the present invention. In the following description, different "embodiments" or "embodiments" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable manner.

[0058] Unless otherwise specified, all materials and reagents mentioned below are commercially available products well-known to those skilled in the art; unless otherwise specified, all methods described are methods known in the art. Unless otherwise defined, the technical or scientific terms used should have the ordinary meaning understood by those skilled in the art. Where specific experimental steps or conditions are not specified below, they can be performed according to the conventional experimental steps or conditions described in the literature in this field.

[0059] Some embodiments of the present invention provide a method for preparing a cellulose solution containing a stabilizer, comprising the following steps:

[0060] S1 involves stirring the ionic liquid and stabilizer at room temperature until a homogeneous mixture is obtained;

[0061] S2. Add cellulose raw material to the mixture obtained in step S1, stir and premix thoroughly at room temperature to form a pre-dissolved cellulose mixture;

[0062] S3. The cellulose mixture obtained in step S2 is heated and stirred until the cellulose raw material is completely dissolved to form a uniform and transparent cellulose solution, which is the cellulose solution containing the stabilizer.

[0063] In the above technical solution, the present invention adds a stabilizer to an ionic liquid, sets different reaction temperatures and water contents, mixes thoroughly, and then dissolves the cellulose raw material until the cellulose raw material is completely dissolved and forms a uniform and transparent solution, thereby observing the effect of the stabilizer on the degradation.

[0064] In some optional embodiments, in step S1, the ionic liquid is selected from at least one of imidazole ionic liquids, pyridine ionic liquids, quaternary ammonium salt ionic liquids, quaternary phosphonium salt ionic liquids, and superbasic ionic liquids. These ionic liquids are selected because they ensure high efficiency, stability, environmental friendliness, compatibility with other components, and economy during the dissolution process. Superbasic ionic liquids and quaternary ammonium salt ionic liquids are preferred. Preferred ionic liquids can achieve high efficiency, stability, and controllability in the dissolution process while ensuring dissolution performance; simultaneously ensuring a balance between economy and environmental protection in the production process, making them particularly suitable for large-scale industrial applications. Furthermore, this selection ensures optimization of the dissolution process by fully leveraging the advantages of various ionic liquids; experiments have shown that the effect of adding a stabilizer is better than other ionic liquids, with more significant color suppression.

[0065] In some optional embodiments, the water content of the ionic liquid in step S1 ranges from 0% to 30%. Adding a certain amount of water to the ionic liquid can reduce the solvent viscosity, ensure that the cellulose can swell sufficiently before dissolving, and prevent the ionic liquid from crystallizing.

[0066] In some optional embodiments, in step S1, the cellulose dissolution temperature is 100–150 °C, the rotation speed is 100–300 rpm, and the vacuum degree is 20–60 bar. The temperature range of 100–150 °C is chosen because the industrial dissolution temperature of cellulose is within this range, and it also simulates the degradation phenomenon in industry, providing a reaction step for the subsequent addition of stabilizers to inhibit degradation. When the rotation speed is below 100 rpm, the mixing is insufficient, mass transfer is inadequate, and the dissolution is unstable. When the rotation speed is above 300 rpm, local cellulose preferentially dissolves, the viscosity of this part of the cellulose solution increases instantaneously, and the remaining cellulose cannot continue to dissolve, causing solid-liquid separation. When the vacuum degree is below 20 bar, it affects the rate and uniformity of the reaction process, reducing the dissolution effect of cellulose. When the vacuum degree is above 60 bar, it is easy to cause the liquid to boil and splash, which is not conducive to the removal of water. The mass percentage concentration of the homogeneous cellulose solution is 2% to 14%. Below 2%, regenerated cellulose materials cannot be prepared; above 14%, dissolution becomes difficult, viscosity is too high, and energy consumption increases. Preferably, it is 3% to 7%. Within this concentration range, cellulose can dissolve relatively completely without excessively high solution viscosity or excessively low dissolution efficiency. At this concentration, the viscosity and flowability of the solution are moderate, which is beneficial for subsequent processing.

[0067] In some alternative embodiments, in step S1, the stabilizer is selected from one of the following components:

[0068] Phenolic compounds: Butylated hydroxytoluene (BHT), tert-butylhydroquinone (TBHQ), butylated hydroxyanisole (BHA), butylated hydroxyanisole (BHM), ethyl gallate (EG), probucol (PB); phenolic stabilizers possess strong antioxidant properties, effectively inhibiting the generation of free radicals in the reaction system, thereby preventing oxidation reactions. When selecting them, their effectiveness in protecting the target dissolution process and the product must be considered.

[0069] Phosphate esters: Triethyl phosphite (TEP), tris(2,4-di-tert-butylphenyl) phosphite (TP), phosphite (PE), tris(2,4-di-tert-butylphenyl) phosphate (TBP), di(2-ethylhexyl) phosphite (DOPO); Phosphate esters are excellent antioxidants and stabilizers, effectively inhibiting oxidation reactions in liquids and preventing chemical degradation during dissolution. Furthermore, they exhibit good thermal stability at high temperatures, making them suitable for high-temperature dissolution processes. The selection of phosphate esters requires consideration of their chemical stability in the dissolution system, volatility, and potential environmental impact.

[0070] Organic acids and their salts include: sodium citrate (SC), malic acid (MA), calcium pantothenate (CP), ascorbic acid (AA), sodium ascorbate (SAC), calcium ascorbate (CAC), potassium ascorbate (KAC), sodium lactate, calcium lactate, potassium lactate, fumaric acid, and potassium tartrate. Organic acids and their salts help regulate the pH of the solution, providing a buffering effect and preventing adverse reactions caused by drastic changes in pH. Appropriate organic acids and their salts should be selected based on the acid-base properties of the reaction system to ensure system stability and avoid excessive acidity or alkalinity affecting the dissolution process.

[0071] Sulfites: Sodium bisulfite, sodium thiosulfate, sodium metabisulfite, sodium hydrosulfite, calcium sulfite, sodium hydrocyanate; sulfites have strong reducing properties and can effectively remove oxidants and free radicals in solution, preventing oxidation reactions. They play an important role in protecting solution components from oxidation, and are particularly suitable for processes requiring protection against oxidative degradation. When selecting sulfites, it is important to note their strong reducing properties, as they may affect other components in the solution; therefore, dosage control is necessary during use.

[0072] Amino compounds: N-acetylcysteine ​​(NAC), 30% hydroxylamine (HA), meclizine, hydroxylamine hydrochloride (HH), hydroxylamine sulfate (SH), hydroxylamine nitrate, sodium diethyldithiocarbamate (DETC); amino compounds generally have strong electrophilic properties and can react with oxidants in solution, thereby preventing oxidative degradation of the solution. The selection of amino compounds needs to consider their compatibility with other chemical components in the reaction system, as well as possible side reactions.

[0073] Metal complexes: Disodium edetate (EDTA), ethylenediaminetetraacetate, ferrous chloride, iron-manganese complexes; metal complexes are commonly used to inhibit catalytic reactions caused by metal ions in solution, preventing the oxidative degradation of target substances by metal ions. The selection of metal complex stabilizers should be based on the types of metal ions in the system and their potential interactions to avoid interference with the solution.

[0074] Organotin compounds: dibutyltin cinnamate (DBC), isooctyltin (IOT), diethyldibutyltin (DDBT); organotin compounds are mainly used for catalysis and stabilization of certain chemical reactions. In preventing oxidative degradation, these compounds act as catalysts, enhancing stability. They possess a certain degree of toxicity, and their concentration must be strictly controlled during selection to ensure safety and environmental compliance.

[0075] Plant extracts include chlorogenic acid (CGA), proanthocyanidins (PA), tocopherol (VE), resveratrol, and olive leaf extract. These plant extract stabilizers are rich in natural antioxidants, effectively preventing oxidative degradation of the solution, and exhibit low toxicity and good environmental friendliness. The selection of plant extracts must ensure their effective protection of the solution system while avoiding the introduction of excessive impurities or interference with dissolution.

[0076] Esters: polyethylene glycol succinate (PES), ascorbate palmitate (AP), tocopheryl palmitate (TA), stearate antioxidants (SE), isophorone diester (ID); ester stabilizers have good antioxidant properties in solution, and can also improve the rheological properties of the solution and reduce precipitation. When selecting ester compounds, their impact on solution stability and potential side effects need to be considered.

[0077] Choosing a suitable stabilizer can improve the solution's temperature and oxidation resistance; control potential side reactions during dissolution; protect sensitive components in the reaction system and extend the product's shelf life; enhance environmental friendliness and reduce potential harm to the environment and human health.

[0078] In some optional embodiments, the concentration of the stabilizer in step S1 ranges from 0.01% to 5% of the total mass of the ILs. Choosing a lower concentration of stabilizer effectively prevents the degradation of ILs under high-temperature conditions, ensuring their stability and without negatively impacting the solubility of cellulose. Excessively high stabilizer concentrations may trigger unnecessary side reactions, generating additional byproducts, which not only affects the quality of the final product but may also lead to additional costs during production. Therefore, controlling the stabilizer concentration within this range balances stability and solubility, while optimizing production efficiency and cost. Below the lower limit (<0.01%), the stabilizer concentration is too low to effectively inhibit the degradation reaction of ionic liquids (ILs) under high-temperature or long-term use conditions. Above the upper limit (>5%), side reactions increase, leading to increased costs.

[0079] In some optional embodiments, in step S2, the cellulose raw material may be selected from at least one of microcrystalline cellulose, wood dissolving pulp, cotton pulp, wheat straw dissolving pulp, reed dissolving pulp, straw dissolving pulp, moso bamboo dissolving pulp, bamboo stalk dissolving pulp, bamboo mulberry dissolving pulp, and hard-headed yellow bamboo dissolving pulp. Wood dissolving pulp, cotton pulp, and bamboo dissolving pulp have wide supply channels, facilitating industrial production. Renewable raw materials such as crop straw and reeds can reduce costs, but the purity, impurities, and structure of cellulose may vary among different raw materials. Selecting high-quality raw materials (wood dissolving pulp, cotton pulp, and moso bamboo dissolving pulp) can reduce impurities and improve dissolution efficiency and uniformity. The crystallinity, fiber diameter, and microstructure of cellulose from different plant sources differ, which can affect the dissolution rate and solution viscosity. To balance solubility, processing controllability, and final product performance, wood dissolving pulp, cotton pulp, and moso bamboo dissolving pulp are preferred raw materials. The degree of polymerization (DP) of the cellulose ranges from 100 to 1200. If the DP is too low (e.g., <100), the cellulose molecular chains are too short, resulting in low solution viscosity, which may affect the mechanical properties of the final product. If the DP is too high (e.g., >1200), the molecular chains are too long, leading to slow dissolution and potentially uneven or incomplete dissolution. To ensure the uniformity and effective dissolution of the cellulose raw material, it needs to be dried at 40–80°C after pulverization. If the drying temperature is below the lower limit (40°C) or above the upper limit (80°C), incomplete moisture removal, uneven dissolution, or even structural damage may occur. Therefore, setting the drying temperature range to 40–80°C is to achieve the optimal balance between dissolution effect and product quality, maintaining the structural stability of the cellulose, ensuring uniform moisture removal, avoiding excessive moisture residue, improving the uniformity of the dissolution process, preventing incomplete dissolution, and resulting in lower energy consumption and production costs.

[0080] In some optional embodiments, in step S2, to ensure the cellulose raw material is fully dissolved in the ILs while avoiding excessively high viscosity or decreased dissolution efficiency of the cellulose solution, the amount of cellulose raw material added is 2% to 14% of the total mass of the ILs. Below 2%, the solution concentration is too low, resulting in low viscosity. Although easy to handle, this leads to low cellulose utilization and reduced production efficiency, resulting in insufficient cellulose content in the final product (such as membranes, fibers, or sheets), which may cause a decrease in mechanical properties, thickness uniformity, or structural stability. Above 14%, the cellulose content is too high, significantly increasing solution viscosity, making stirring and mass transfer difficult, and reducing dissolution efficiency. High-viscosity solutions increase the difficulty of operation during pumping, mixing, or molding, increase energy consumption, require more sophisticated equipment, and increase production costs.

[0081] In some optional embodiments, in step S2, the premixing conditions of the cellulose raw material are carried out at room temperature and pressure, and the premixing speed is 100~300 rpm to ensure that the cellulose raw material and the solvent are fully mixed to form a homogeneous pre-dissolved mixture. This setting can ensure that the cellulose raw material and ILs are fully mixed to form a homogeneous pre-dissolved mixture. The preferred speed is 200 rpm to balance mixing efficiency and solution stability, providing optimal conditions for most types of cellulose.

[0082] In some optional embodiments, the heating conditions of the cellulose raw material in step S3 are in the range of 100°C to 150°C. This is because excessively low temperatures, such as below 100°C, are insufficient to maintain the dissolution efficiency of cellulose. Temperatures exceeding 150°C are not suitable for industrial production, and excessively high temperatures may also lead to increased energy consumption, reducing the economic efficiency of the production process. Furthermore, the vacuum level is set in the range of 20 to 60 bar to ensure that water in the system is removed and that the cellulose raw material is fully dissolved at the required temperature. Setting the vacuum level to 20 to 60 bar ensures sufficient removal of moisture, allowing the cellulose to fully swell and dissolve uniformly at the predetermined temperature; a vacuum level below 20 bar results in insufficient dissolution, while a vacuum level above 60 bar is too high, easily leading to sudden boiling and splashing of the liquid, equipment pressure fluctuations, or operational risks.

[0083] In some optional embodiments, in step S3, the resulting uniform and transparent cellulose solution is observed using a polarizing microscope. The absence of bright colored fibers in the field of view indicates that the dissolution process is complete, ensuring the uniformity and transparency of the solution. The highly ordered molecular chains in the crystalline regions of cellulose will appear as bright, colored, or shimmering stripes under polarized light. Upon complete dissolution, the molecular arrangement of cellulose is disrupted, preventing the formation of polarized light differences and resulting in a completely bright appearance.

[0084] In the above technical solution, the present invention adds a certain amount of stabilizer to ILs, sets different reaction temperatures and water contents, mixes thoroughly, and then dissolves the cellulose raw material until the cellulose raw material is completely dissolved and forms a uniform and transparent solution, thereby observing the effect of the stabilizer on the degradation.

[0085] Some embodiments of the present invention also provide a cellulose solution containing a stabilizer, the cellulose solution containing the stabilizer being prepared by the method described above.

[0086] Some embodiments of the present invention also provide the application of a cellulose solution containing a stabilizer in the preparation of regenerated cellulose films and regenerated cellulose fibers.

[0087] In some alternative embodiments, the application includes the following steps:

[0088] a. A cellulose solution is coated onto a glass substrate using a doctor blade, and then placed in a vacuum environment for degassing and leveling to form a thin film;

[0089] b. Immerse the coated glass plate in a coagulation bath, and after it is completely regenerated, remove it, rinse it with deionized water, and dry it in the air to form a film.

[0090] In some optional embodiments, the coating thickness in step a is 0.25–0.80 mm. When the thickness is less than 0.25 mm, the film lacks sufficient mechanical strength during solidification and drying, making it prone to cracking or breakage, which affects operation and yield; while when the thickness is greater than 0.8 mm, the film is too thick, which is not conducive to the regeneration process and reduces production efficiency.

[0091] In some optional embodiments, in step b, a suitable coagulation bath solvent is selected based on the polarity, volatility, and ILs removal efficiency of the solvent. The coagulation bath can be selected from deionized water, anhydrous ethanol, methanol, isopropanol, dimethyl sulfoxide, acetone, acetic acid, and methoxyacetic acid; aqueous solvents are suitable for low-cost and efficient regeneration, while organic solvents (such as ethanol and isopropanol) can help improve other membrane properties. The soaking time in the coagulation bath is 5–30 min. A soaking time range of 5–30 min ensures sufficient ILs removal without causing over-coagulation. Within this time range, the membrane structure and performance remain balanced, exhibiting good mechanical properties.

[0092] Some embodiments of the present invention also provide the application of a cellulose solution containing a stabilizer in the preparation of regenerated cellulose fibers.

[0093] In some alternative embodiments, the application includes the following steps:

[0094] c. The cellulose solution is loaded into a spinning tube and placed in an oven at 60-90°C. Using a wet spinning machine or a dry-jet wet spinning machine, the cellulose solution is extruded through a needle into a coagulation bath, where wet fibers are obtained through solvent exchange. Below the lower limit (<60°C), the cellulose solution has high viscosity and poor flowability, hindering the extrusion process and potentially causing needle blockage or fiber discontinuity. Above the upper limit (>90°C), high-temperature operation increases the risk of solvent evaporation and flammability, requiring strict safety control.

[0095] d. Place the wet fibers obtained in step c in a coagulation bath and let them stand for at least 24 hours, or repeatedly wind and move them through the coagulation bath to ensure sufficient solvent exchange between the wet fibers and the solvent in the coagulation bath. Then, perform continuous drying or intermittent drying in an oven, and finally wind them onto a roller to obtain regenerated cellulose fibers. Choosing to stand in the coagulation bath for at least 24 hours ensures sufficient solvent replacement in the wet fibers, uniform regeneration of the cellulose chains, and stable dry fiber quality and mechanical properties. Less than 24 hours will directly lead to decreased fiber strength, uneven shrinkage, surface defects, and large batch-to-batch variations, affecting product quality and industrial production stability. In the step of repeatedly winding and moving the fibers through the coagulation bath, each pass through the coagulation bath should be 5-10 minutes, and each winding should be performed 3-5 times.

[0096] In some optional embodiments, in step c, the wet spinning machine or dry-jet wet spinning machine uses a gear pump, vacuum pump, peristaltic pump, or injection pump. Gear pumps are suitable for high-viscosity liquids, providing a stable flow rate; vacuum pumps are used to extract solvents or gases, helping to maintain pressure balance and prevent air bubbles. Peristaltic pumps are suitable for precise flow control and are suitable for low-viscosity liquids; injection pumps are suitable for precise liquid flow control and continuous, stable liquid delivery. The spinning needle is one of 10G to 32G; larger needles are suitable for higher flow rates of solutions or coarser fibers. Smaller needles are suitable for fine fibers or low flow rates of solutions. Needles smaller than 10G may result in excessively fine fibers, easily causing blockages, or excessively slow flow rates, affecting production efficiency. Needles larger than 32G may result in excessively large fibers, potentially failing to meet the required fiber performance requirements, leading to unsatisfactory mechanical properties of the final product. The extrusion speed is 0.05–0.5 mL / min; lower speeds are suitable for applications requiring high fiber precision, helping to ensure fiber consistency. Higher extrusion speeds are suitable for high-volume production environments, appropriately improving production efficiency. Extrusion speeds below 0.05 mL / min are too slow, potentially leading to poor solution flowability and even discontinuous fiber formation, affecting fiber uniformity and quality. Speeds above 0.5 mL / min are too fast, potentially causing the solution to fail to solidify in time, resulting in uneven fiber formation, or even bubble formation or fiber breakage. The extrusion temperature is 25–120℃. Lower temperatures are suitable for solutions that are relatively stable or can maintain a stable state at room temperature. Higher temperatures are suitable for improving solution flowability and reducing cellulose solution viscosity, generally applicable to higher concentration cellulose solutions. Temperatures below the lower limit (<25℃) may result in excessively high solution viscosity. At lower temperatures, the cellulose solution has poor flowability, potentially causing needle blockage during spinning or uneven fiber formation. Temperatures above the upper limit (>120℃) may cause the solution to evaporate too quickly, leading to uneven fiber formation and even affecting fiber shrinkage and strength.

[0097] In some optional embodiments, in step d, the coagulation bath may be selected from one of deionized water, anhydrous ethanol, methanol, isopropanol, dimethyl sulfoxide, acetone, acetic acid, and methoxyacetic acid. This selection has the following advantages: ensuring complete cellulose regeneration; removing ionic liquids or other solvents from the original solution through solvent exchange; controlling fiber quality: different solvents can adjust fiber surface smoothness, porosity, and diameter uniformity; balancing production efficiency and safety: selecting a suitable solvent ensures effective fiber regeneration while facilitating operation, reducing costs, and minimizing safety risks.

[0098] In some optional embodiments, step d involves continuous drying using online equipment or intermittent drying in an oven. Sufficient time must be allowed for the fibers to pass through the drying zone to ensure complete removal of moisture or solvents; the drying temperature must be controlled within the tolerance range of cellulose to prevent degradation; wind speed, heating method, and humidity must be coordinated to prevent excessively rapid drying of the fiber surface, resulting in wrinkles or uneven shrinkage. Ensuring fiber stability: forming a stable solid structure to guarantee consistent mechanical properties and dimensions. Ensuring fiber surface quality: smooth, wrinkle-free, and bubble-free. Improving industrial controllability: continuous or intermittent drying can be selected according to production needs, achieving a balance between output and quality. Preventing safety risks: reasonable control of temperature and humidity to avoid solvent residue and evaporation of flammable solvents.

[0099] The present invention will be further described below with reference to specific embodiments, but this should not be construed as a limitation on the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the above description of the present invention still fall within the scope of protection of the present invention.

[0100] Unless otherwise specified, all materials and reagents mentioned below are commercially available products well known to those skilled in the art; unless otherwise specified, all methods described are methods known in the art. Unless otherwise defined, the technical or scientific terms used should have the ordinary meaning understood by those skilled in the art to which this invention pertains.

[0101] I. Preparation of Cellulose Solution

[0102] Example 1

[0103] Take 20g of anhydrous tetrabutylammonium chloride ([N(Bu)4][Cl]), add 0.07wt% of the phosphate ester stabilizer tris(2,4-di-tert-butylphenyl) phosphite (TP), mix thoroughly at room temperature, then add 1g of cotton pulp dissolving slurry (purchased from Shandong Yinying Co., Ltd., DP=898), and premix using a rotary evaporator at room temperature for 30min at 200rpm. Then heat to 140℃ and apply a vacuum of 20bar to prepare a homogeneous cellulose solution containing the phosphate ester stabilizer. The viscosity of the resulting cellulose solution is 23.26 Pa·s. The method for preparing the regenerated solution for measuring UV absorbance is the same as in Comparative Example 1.

[0104] Example 2

[0105] Take 20g of anhydrous 1-allyl-3-methylimidazolium chloride, add 0.5wt% of tocopherol (VE) to the 1-allyl-3-methylimidazolium chloride, mix thoroughly at room temperature, then add 1g of bamboo dissolving pulp (purchased from Sichuan Yibin Paper Industry Co., Ltd., DP=695), and premix using a rotary evaporator at room temperature for 30min at a speed of 200rpm. Then heat to 130℃ and apply a vacuum of 30bar to prepare a homogeneous cellulose solution containing plant extract stabilizers. The viscosity of the resulting cellulose solution is 132.68 Pa·s. The method for preparing the regenerated solution for measuring UV absorbance is the same as in Comparative Example 1.

[0106] Example 3

[0107] Take 20g of anhydrous N-allylpyridinium chloride ([APy][Cl]), add 0.8wt% ascorbic acid (AA) to the N-allylpyridinium chloride, mix thoroughly at room temperature, then add 1g of wood dissolving pulp (purchased from Xinjiang Zhongtai (Group) Co., Ltd., DP=800), and premix using a rotary evaporator at room temperature for 30min at 180rpm. Then heat to 125℃ and apply a vacuum of 20bar to prepare a homogeneous cellulose solution containing organic acids and their salt stabilizers. The viscosity of the resulting cellulose solution is 43.53 Pa·s. The method for preparing the regenerated solution for measuring UV absorbance is the same as in Comparative Example 1.

[0108] Example 4

[0109] Take 20g of anhydrous 1,8-diazabicyclo[5.4.0]undec-7-ene acetate ([DBUH][CH3COO]), add 0.06wt% of tocopheryl palmitate (TA) to the mixture, and mix thoroughly at room temperature. Then add 1g of wood dissolving pulp (purchased from Xinjiang Zhongtai (Group) Co., Ltd., DP=800), and premix using a rotary evaporator at room temperature for 30min at 150rpm. Subsequently, heat to 130℃ and apply a vacuum of 20bar to prepare a homogeneous cellulose solution containing ester stabilizers. The viscosity of the resulting cellulose solution is 44.68 Pa·s. The method for preparing the regenerated solution for measuring UV absorbance is the same as in Comparative Example 1.

[0110] Example 5

[0111] Take 20 g of anhydrous tetrabutylammonium acetate (TBAAc), add 0.3% (by mass) of butylated hydroxytoluene (BHT) to the mixture, and mix thoroughly at room temperature. Then add 1 g of *Cibotium barbarum* dissolving pulp (purchased from Sichuan Yibin Paper Industry Co., Ltd., DP=770), and premix using a rotary evaporator at room temperature for 30 min at 100 rpm. Subsequently, heat to 100 °C and apply a vacuum of 35 bar to prepare a homogeneous cellulose solution containing phenolic stabilizers. The viscosity of the resulting cellulose solution is 62.97 Pa·s. The method for preparing the regenerated solution for measuring UV absorbance is the same as in Comparative Example 1.

[0112] Example 6

[0113] Take 20 g of anhydrous 1,5-diazabicyclo[4.3.0]non-5-enium acetate ([DBNH][CH3COO]), add 0.05 wt% hydroxylamine sulfate (SH) of the 1,5-diazabicyclo[4.3.0]non-5-enium acetate, mix thoroughly at room temperature, then add 1 g of bamboo dissolving pulp (purchased from Sichuan Yibin Paper Industry Co., Ltd., DP=695), and premix using a rotary evaporator at room temperature for 30 min at a speed of 300 rpm. Then heat to 130 ℃ and apply a vacuum of 20 bar to prepare a homogeneous cellulose solution containing an amino compound stabilizer. The viscosity of the resulting cellulose solution is 27.11 Pa·s. The method for preparing the regenerated solution for measuring UV absorbance is the same as in Comparative Example 1.

[0114] Example 7

[0115] Take 20 g of anhydrous 1,8-diazabicyclo[5.4.0]undec-7-enonium methoxyacetate ([DBUH][CH3OCH2COO]), add hydroxylamine (HA) at 1.00 wt% of the mass of the 1,8-diazabicyclo[5.4.0]undec-7-enonium methoxyacetate, mix thoroughly at room temperature, then add 1 g of wood dissolving pulp (purchased from Xinjiang Zhongtai (Group) Co., Ltd., DP=800), and premix using a rotary evaporator at room temperature for 30 min at a speed of 200 rpm. Then heat to 140 ℃ and apply a vacuum of 20 bar to prepare a homogeneous cellulose solution containing an amino compound stabilizer. The viscosity of the resulting cellulose solution is 31.08 Pa·s. The method for preparing the regenerated solution for measuring UV absorbance is the same as in Comparative Example 1.

[0116] Example 8

[0117] Take 20 g of 1,8-diazabicyclo[5.4.0]undec-7-enium methoxy acetate ([DBUH][CH3OCH2COO]) with a water content of 20 wt%, then add hydroxylamine (HA) at 2.5 wt% of the mass of the 1,8-diazabicyclo[5.4.0]undec-7-enium methoxy acetate. After thoroughly mixing at room temperature, add 1 g of *Cibotium barbarum* dissolving pulp (purchased from Sichuan Yibin Paper Industry Co., Ltd., DP=770). Premix using a rotary evaporator at room temperature for 30 min at a speed of 200 rpm. Then heat to 100 ℃ and apply a vacuum of 20 bar to dissolve the cellulose while removing water under vacuum, thus preparing a homogeneous cellulose solution containing an amino compound stabilizer. The viscosity of the obtained cellulose solution is 27.65 Pa·s. The method for preparing the regenerated solution for measuring UV absorbance is the same as in Comparative Example 1.

[0118] Example 9

[0119] Take 20 g of tetrabutylammonium acetate (TBAAc) with a water content of 5 wt%, then add 0.6 wt% ascorbyl palmitate (AP) of the tetrabutylammonium acetate (TBAAc), and mix thoroughly at room temperature. Then add 1 g of wood dissolving pulp (purchased from Xinjiang Zhongtai (Group) Co., Ltd., DP=800), and premix using a rotary evaporator at room temperature for 30 min at a speed of 200 rpm. Subsequently, heat to 120 ℃, apply a vacuum of 20 bar, and dissolve while removing water under vacuum to prepare a homogeneous cellulose solution containing an amino compound stabilizer. The viscosity of the resulting cellulose solution is 30.22 Pa·s. The method for preparing the regenerated solution for measuring UV absorbance is the same as in Comparative Example 1.

[0120] Example 10

[0121] Take 20 g of 1,5-diazabicyclo[4.3.0]non-5-enium methoxy acetate [DBNH][CH3OCH2COO] with a water content of 30 wt%, then add 1.5 wt% butylated hydroxyanisole (BHA) based on the mass of the 1,5-diazabicyclo[4.3.0]non-5-enium methoxy acetate. After thoroughly mixing at room temperature, add 1 g of bamboo dissolving pulp (purchased from Sichuan Yibin Paper Industry Co., Ltd., DP=695). Premix using a rotary evaporator at room temperature for 30 min at a speed of 200 rpm. Then raise the temperature to 120 ℃ and apply a vacuum of 20 bar to dissolve the cellulose while removing water under vacuum, thus preparing a homogeneous cellulose solution containing an amino compound stabilizer. The viscosity of the obtained cellulose solution is 36.74 Pa·s. The method for preparing the regenerated solution for measuring UV absorbance is the same as in Comparative Example 1.

[0122] Comparative Example 1

[0123] 20 g of anhydrous 1,8-diazabicyclo[5.4.0]undec-7-enium methoxy acetate ([DBUH][CH3OCH2COO]) was added to 1 g of wood solvent (DP=800, purchased from Xinjiang Zhongtai (Group) Co., Ltd.) at room temperature. The mixture was premixed using a rotary evaporator at 200 rpm for 30 min. This premixing process facilitated initial contact and dispersion of the solvents with the wood solvent, ensuring uniformity in the subsequent dissolution process. Next, the temperature was raised to 140 °C, and the system vacuum was maintained at 40 bar to dissolve the cellulose, yielding a cellulose solution. The viscosity of the cellulose solution was measured to be 28.14 Pa·s. Subsequently, 5 g of the cellulose solution was pressed into a film and immersed in 150 times its weight of deionized water, allowing it to stand for 24 h until the solvents were completely replaced. Finally, the absorbance curve of the immersed solution was measured using a UV-Vis spectrophotometer, with the scanning range set to 200–500 nm.

[0124] Comparative Example 2

[0125] 20 g of 1,8-diazabicyclo[5.4.0]undec-7-enium acetate ([DBNH][CH3COO]) with a water content of 30 wt% was taken and thoroughly mixed at room temperature. Then, 1 g of wood dissolving pulp (purchased from Xinjiang Zhongtai (Group) Co., Ltd., DP=800) was added. The mixture was premixed for 30 min at room temperature using a rotary evaporator at a speed of 200 rpm. Subsequently, the temperature was raised to 100 ℃, and a vacuum of 20 bar was applied to dissolve the cellulose while removing water under vacuum, thus preparing a homogeneous cellulose solution without stabilizers. The viscosity of the resulting cellulose solution was 25.72 Pa·s. The method for preparing the regenerated solution for measuring UV absorbance was the same as in Comparative Example 1.

[0126] The parameters and absorbance obtained in the comparative examples and Examples 1-10 are summarized in Table 1.

[0127] Table 1

[0128]

[0129] Where “—” indicates that it does not exist; the viscosity is the rheology of the cellulose solution at 100 °C.

[0130] Following the methods of the comparative examples and embodiments described above, color change is the most intuitive physical characteristic. The results of Comparative Examples 1 and 2 show that ILs undergo significant degradation under high temperature or aqueous conditions, resulting in a marked deepening of color. Figure 1 This demonstrates that the color of the cellulose solution gradually deepens with increasing temperature, indicating that high temperature leads to degradation. This was confirmed by UV-Vis spectroscopy analysis (e.g., ...). Figure 2 As shown in the image, ILs exhibited a strong absorption band in the 200–250 nm wavelength range, primarily attributed to the absorption characteristics of chemical groups such as CN, CN2, and -COOH. Notably, a significant absorption peak appeared at 298 nm, indicating the formation of new chromophores (-NH2) and chromophores (-CONH) within the ILs during degradation. These newly formed groups are key factors contributing to the deepening color of the ILs. Furthermore, Figure 3 The data in the comparative examples show that the viscosity of ILs decreases with increasing temperature, further verifying the degradation of ILs at high temperatures. Experimental results from Examples 1-7 revealed that ILs exhibited varying degrees of color change under different stabilizers. The UV spectroscopy results in Table 1 further demonstrate that different stabilizers have varying effects on inhibiting the color deepening of ILs at high temperatures, indicating that the rational selection and use of stabilizers is crucial for improving the thermal stability of ILs and the quality of regenerated cellulose. Furthermore, experimental results from Examples 6 and 7 further demonstrate that the amount of stabilizer added significantly affects the color inhibition effect. Excessive stabilizer addition not only increases the economic cost of the system but may also lead to increased solution viscosity and the introduction of byproducts; while insufficient stabilizer dosage makes it difficult to effectively inhibit degradation. Therefore, the use of stabilizers should follow the principle of "minimum effective dose" to balance cost, process, and performance. In Example 6, after adding the stabilizer at 130°C, the color of the cellulose solution became lighter, with its color value even lower than the result under conventional 80°C dissolution conditions (e.g., ...). Figure 4(As shown in the figure). This phenomenon indicates that the stabilizer has excellent protective effects in high-temperature environments. The mechanism may lie in the high reactivity of the hydroxyl groups within the amino compound stabilizer molecule, which can act as hydrogen atom donors, thereby exerting an antioxidant effect; simultaneously, the generated nitroxide radicals can capture the alkyl and carbonyl radicals of ILs before they oxidize, effectively blocking subsequent oxidation reactions. Therefore, the stabilizer described in this invention can significantly improve the stability of ILs at high temperatures through the dual effects of free radical scavenging and antioxidant activity.

[0131] Furthermore, the experimental results of Comparative Examples 2 and Examples 8-10 show that the stabilizer can effectively inhibit the hydrolysis reaction of ILs under high humidity conditions. This finding significantly expands the application scope of the stabilizer of the present invention. Specifically, the stabilizer has a significant inhibitory effect on the hydrolysis reaction under certain humidity conditions. However, when the moisture content in the environment exceeds a certain proportion (e.g., 30%), the intensity of the hydrolysis reaction increases significantly, and the inhibitory effect of the stabilizer is no longer significant. This indicates that the inhibitory effect of the stabilizer is only effective within a certain range of moisture content; excessively high moisture content weakens the effect of the stabilizer.

[0132] II. Preparation of Regenerated Cellulose Film

[0133] Example 1

[0134] Weigh 0.10 g of butylated hydroxytoluene (BHT) and 20 g of anhydrous 1,8-diazabicyclo[5.4.0]undec-7-enium acetate ([DBNH][CH3COO]), and mix thoroughly at room temperature until homogeneous. Then add 0.6 g of wood solvent (purchased from Xinjiang Zhongtai (Group) Co., Ltd., DP=800). Premix at room temperature for 30 min at 200 rpm. Then heat the mixture to 130°C, set the stirring speed to 300 rpm, and continue stirring under a vacuum of 30 bar until the wood solvent is completely dissolved. Finally, pour the cellulose solution onto a glass plate preheated to 130°C for 20 min, and uniformly coat it into a film using a 0.25 mm doctor blade. Regenerate the resulting film in deionized water for 10 min. Then wash the resulting film five times with deionized water to ensure complete removal of impurities. The cleaned regenerated membrane was dried in an oven at 120 °C for 15 min to obtain the final regenerated cellulose film.

[0135] This embodiment obtains the CIE diagram (e.g., by detecting the coagulation bath of the regenerated film) Figure 5(As shown). Experimental results show that the color saturation (coordinates: X=0.179, Y=0.184) after adding 0.5% stabilizer at 130℃ is significantly lower than the color saturation (coordinates: X=0.228, Y=0.284) after complete degradation (130℃), and close to the color saturation obtained by normal dissolution at 80℃ (coordinates: X=0.286, Y=0.281). This change indicates that the addition of stabilizer significantly inhibits the degradation reaction and effectively slows down the color deepening process, and the value approaches the center position of the CIE graph, further verifying the inhibitory effect of the stabilizer. To further evaluate the performance of the regenerated film, the regenerated cellulose film was cut to a fixed size and placed in the fixture of the Zwick / Roell tensile testing machine, with the longitudinal axis of the film aligned with the center of the fixture. The tensile test was started until the film broke. Test results show that the tensile strength of the film obtained after simulated degradation is 9.04 MPa, while the strength of the regenerated cellulose film with added stabilizer reaches 16.30 MPa, almost twice the strength of the film without stabilizer (e.g., Figure 6 (As shown in the image). This significant enhancement not only demonstrates that the stabilizer, while inhibiting the high-temperature degradation of ILs, also improves the mechanical properties of the recycled material. This result further broadens the application areas of regenerated cellulose films, especially in applications requiring high strength and durability. The addition of the stabilizer can significantly extend their service life and improve their versatility and stability in industrial applications.

[0136] Example 2

[0137] Weigh 20 g of tetrabutylammonium acetate (TBAAc) with a water content of 30 wt%, add 0.24 g of tocopheryl palmitate (TA), and mix thoroughly at room temperature to ensure homogeneity. Then add 0.8 g of bamboo dissolving pulp (purchased from Sichuan Yibin Paper Industry Co., Ltd., DP=695). Premix using a rotary evaporator at room temperature for 30 min at a speed of 200 rpm. Subsequently, heat to 100 °C, apply a vacuum of 10 bar, and dissolve while removing water under vacuum to prepare a homogeneous cellulose solution containing ester stabilizers. Finally, pour the cellulose solution onto a glass plate preheated at 100 °C for 20 min, and uniformly coat it into a film using a 0.25 mm doctor blade. The resulting film is coagulated in ethanol at room temperature for 20 min. Then, wash the resulting film five times with deionized water, and finally dry it in a 120 °C oven for 15 min to obtain a regenerated cellulose film. To further evaluate the performance of the recycled film, the recycled cellulose film was cut to a fixed size and placed in the fixture of a Zwick / Roell tensile testing machine, with the longitudinal axis of the film aligned with the center of the fixture. The tensile test was started until the film broke. The test results showed that the tensile strength of the film obtained after simulated degradation was 3.17 MPa, while the strength of the recycled cellulose film with the addition of the stabilizer reached 3.42 MPa. The test results indicate that this type of stabilizer has no adverse effects on the mechanical properties of the recycled film under high humidity conditions.

[0138] III. Preparation of Regenerated Cellulose Fibers

[0139] Example 1

[0140] 0.01 g of hydroxylamine (HA) was weighed and added to 20 g of anhydrous [DBUH][CH3OCH2COO], and thoroughly mixed at room temperature. Then, 0.8 g of bamboo dissolving pulp (purchased from Sichuan Yibin Paper Industry Co., Ltd., DP=695) was added, and the mixture was premixed at 200 rpm for 30 min. Next, the mixture was heated to 130℃, the stirring speed was increased to 300 rpm, and stirring continued under a vacuum of 30 bar until the cellulose was completely dissolved, obtaining a homogeneous cellulose solution. The resulting cellulose solution was used as the spinning solution and extruded into a 25℃ ethanol (95% purity) coagulation bath at 0.3 mL / min under 0.4 MPa pressure and 80℃. After soaking in the coagulation bath for 12 h, the cellulose filaments were dried in a 60℃ oven to obtain regenerated cellulose fibers. As a control experiment, the above steps were repeated under the same process conditions, but without the addition of stabilizers, to prepare high-temperature degradable regenerated cellulose fibers. Both groups of fibers underwent spinning and drying processes in the same manner. Finally, the performance of regenerated cellulose fibers with and without stabilizers was compared. The results showed that after soaking in the same coagulation bath for the same time, the regenerated cellulose fibers with stabilizers appeared more translucent and had a lighter color; while the control group fibers without stabilizers appeared slightly cloudy and had a darker yellow color (e.g., ...). Figure 7 (As shown). In addition, the surface functional groups (e.g., cellulose raw materials, unstabilized regenerated cellulose fibers, and stabilized regenerated cellulose fibers) were analyzed. Figure 8 (As shown). Regenerated cellulose fibers at 3359, 2894, 1161, and 1023 cm⁻¹. −1 A series of absorption bands appear at the point, corresponding to -OH, -CH2, COC, and CO groups, respectively. After regeneration, the COC vibration of the cellulose feedstock is between 1180 and 1058 cm⁻¹. −1 The broadband range still exists, indicating that the macromolecular structure of cellulose did not degrade during the high-temperature dissolution process. (The text abruptly shifts to a seemingly unrelated topic about cellulose raw materials at 3313 cm⁻¹.) −1 Compared to the OH vibration absorption band at 3359 cm⁻¹, the OH vibration absorption band of regenerated cellulose fibers is oriented towards 3359 cm⁻¹. −1 The blue shift indicates that the hydrogen bond network of the raw material was disrupted to some extent. Furthermore, the characteristic peaks of the stabilizer were not detected in the regenerated cellulose fibers without the added stabilizer, suggesting that the stabilizer is completely dissolved in the ILs and displaced into the coagulation bath along with the ILs during regeneration, without remaining in the regenerated cellulose material.

[0141] Example 2

[0142] 0.12 g of hydroxylamine sulfate (SH) was weighed and added to 20 g of [DBUH][CH3OCH2COO] with a water content of 10 wt%, and stirred thoroughly at room temperature. Then, 0.6 g of *Cibotium barometz* dissolving pulp (purchased from Sichuan Yibin Paper Industry Co., Ltd., DP=770) was added, and the mixture was premixed for 30 min at room temperature using a rotary evaporator at a speed of 200 rpm. The mixture was then heated to 120 ℃ and subjected to a vacuum of 20 bar, dissolving the cellulose while removing water under vacuum to prepare a homogeneous cellulose solution containing an amino compound stabilizer. The resulting cellulose solution was used as the spinning solution and extruded into a 25 ℃ deionized water coagulation bath at 0.2 mL / min under a pressure of 0.3 MPa and a temperature of 90 ℃. After soaking in the coagulation bath for 12 h, the cellulose fibers were dried in a 60 ℃ oven to obtain regenerated cellulose fibers. As a control experiment, the above steps were repeated under the same process conditions, but without the addition of stabilizers, to prepare regenerated cellulose fibers with high water content degradation. Both groups of fibers were spun and dried in the same manner. The final dry tensile strengths of the regenerated cellulose fibers with and without stabilizers were 2.32 cN / dtex and 1.99 cN / dtex, respectively. The test results indicate that the stabilizer can inhibit the hydrolysis of ILs and enhance the mechanical properties of the regenerated fibers even under high humidity conditions.

[0143] In summary, by rationally selecting stabilizers and their dosage, this invention effectively inhibits the degradation and hydrolysis reactions of ILs under high temperature and high humidity environments, significantly improving the stability of ILs and the quality of regenerated cellulose, and providing important technical support for applications in related fields.

[0144] Numerous specific details are set forth in this specification. However, it will be understood that embodiments of the invention may be practiced without these specific details. In some embodiments, well-known methods, structures, and techniques have not been shown in detail so as not to obscure the understanding of this specification.

[0145] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0146] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

[0147] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A method for preparing a cellulose solution containing a stabilizer, characterized in that, Includes the following steps: S1. The ionic liquid and stabilizer are stirred and mixed at room temperature until a homogeneous mixture is obtained; the ionic liquid is selected from at least one of imidazole ionic liquids, pyridine ionic liquids, quaternary ammonium salt ionic liquids, quaternary phosphonium salt ionic liquids, and superbasic ionic liquids; the stabilizer is selected from one of phenols, phosphate esters, organic acids and their salts, sulfites, amino compounds, metal complexes, organotin compounds, plant extracts, and esters; the concentration range of the stabilizer is 0.01% to 5% of the total mass of the ionic liquid; S2. Add cellulose raw material to the mixture obtained in step S1, stir and premix thoroughly at room temperature to form a pre-dissolved cellulose mixture; S3 The cellulose mixture obtained in step S2 is heated and stirred at 100 ℃~150 ℃ and 20~60 bar until the cellulose raw material is completely dissolved to form a uniform and transparent cellulose solution, which is the cellulose solution containing the stabilizer.

2. The method for preparing a cellulose solution containing a stabilizer as described in claim 1, characterized in that, In step S1, the water content of the ionic liquid ranges from 0% to 30%; the mass percentage concentration of the homogeneous cellulose solution is from 2% to 14%.

3. The method for preparing a cellulose solution containing a stabilizer as described in claim 2, characterized in that, In step S1, the phenols are selected from one of butylated hydroxytoluene, tert-butylhydroquinone, butylated hydroxyanisole, butylated hydroxyanisole, ethyl gallate, and probucol; the phosphates are selected from one of triethyl phosphite, tris(2,4-di-tert-butylphenyl) phosphite, phosphite, tris(2,4-di-tert-butylphenyl) phosphate, and di(2-ethylhexyl) phosphite; the organic acids and their salts are selected from one of sodium citrate, malic acid, calcium pantothenate, ascorbic acid, sodium ascorbate, calcium ascorbate, potassium ascorbate, sodium lactate, calcium lactate, potassium lactate, fumaric acid, and potassium tartrate; the sulfites are selected from one of sodium bisulfite, sodium thiosulfate, and pyroxene. The compound is selected from sodium sulfite, sodium hydrosulfite, calcium sulfite, and sodium hydrocyanate; the amino compound is selected from N-acetylcysteine, 30% hydroxylamine, mecobalamin, hydroxylamine hydrochloride, hydroxylamine sulfate, hydroxylamine nitrate, and sodium diethyldithiocarbamate; the metal complex is selected from disodium edetate, ferrous chloride, and iron-manganese complex; the organotin compound is selected from isooctylstannous and diethyldibutyltin; the plant extract is selected from chlorogenic acid, proanthocyanidins, tocopherol, resveratrol, and olive leaf extract; the ester is selected from polyethylene glycol succinate, ascorbyl palmitate, tocopheryl palmitate, stearate antioxidants, and isophorone diester.

4. The method for preparing a cellulose solution containing a stabilizer as described in claim 1, characterized in that, In step S2, the cellulose raw material is selected from at least one of microcrystalline cellulose, wood dissolving pulp, cotton pulp, wheat straw dissolving pulp, reed dissolving pulp, straw dissolving pulp, moso bamboo dissolving pulp, bamboo dissolving pulp, mian bamboo dissolving pulp, and hard-headed yellow bamboo dissolving pulp; the degree of polymerization of the cellulose raw material is in the range of 100 to 1200; the amount of cellulose raw material added is 2% to 14% of the total mass of the ionic liquid; the premixing conditions of the cellulose raw material are carried out at room temperature and pressure, and the premixing speed is 100 to 300 rpm.

5. A cellulose solution containing a stabilizer, characterized in that, The cellulose solution containing the stabilizer is prepared by the method according to any one of claims 1-4.

6. The use of the cellulose solution containing a stabilizer as described in claim 5 in the preparation of regenerated cellulose films.

7. The application of the cellulose solution containing a stabilizer as described in claim 6 in the preparation of regenerated cellulose films, characterized in that, The application includes the following steps: a. A cellulose solution is coated onto a glass substrate using a doctor blade, and then placed in a vacuum environment for degassing and leveling to form a thin film; b. Immerse the coated glass plate in a coagulation bath, and after it is completely regenerated, remove it, rinse it with deionized water, and dry it in the air to form a film. In step a, the coating thickness is 0.25–0.80 mm; in step b, the coagulation bath is selected from one of deionized water, anhydrous ethanol, methanol, isopropanol, dimethyl sulfoxide, acetone, acetic acid, and methoxyacetic acid, and the soaking time in the coagulation bath is 5–30 min.

8. The use of the cellulose solution containing a stabilizer as described in claim 5 in the preparation of regenerated cellulose fibers.

9. The application of the cellulose solution containing a stabilizer as described in claim 8 in the preparation of regenerated cellulose fibers, characterized in that, The application includes the following steps: c. The cellulose solution is spun at 80 °C by wet spinning or dry-jet wet spinning and then extruded through a needle into a coagulation bath to obtain wet fibers through solvent exchange. d. Place the wet fiber obtained in step c in a coagulation bath and let it stand for more than 24 hours, or repeatedly wind and move it through the coagulation bath to allow the wet fiber to fully exchange solvent with the solvent in the coagulation bath. Then, continuously dry or intermittently dry in an oven to obtain regenerated cellulose fiber. In step c, the spinning needle used in the wet spinning or dry-jet wet spinning is one of 10G to 32G; the extrusion speed is 0.05 to 0.5 mL / min; and the extrusion temperature is 25 to 120℃. In step d, the coagulation bath is selected from one of deionized water, anhydrous ethanol, methanol, isopropanol, dimethyl sulfoxide, acetone, acetic acid, and methoxyacetic acid.

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