Cellulose ester derivative, high-concentration fiber oily solution and preparation method thereof
By modifying cellulose ester derivatives with co-reactants and combining them with a washing-filtration process, the problem of easy agglomeration of cellulose in non-polar solvents is solved, achieving stable dispersion of high-concentration cellulose oily solutions and simplifying production, which is suitable for applications such as lithium battery separators.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-01-07
- Publication Date
- 2026-04-03
AI Technical Summary
In existing technologies, high-concentration cellulose oily solutions tend to agglomerate in non-polar solvents. The dispersion process requires a large amount of organic solvents, which increases production costs and poses environmental and safety hazards. Furthermore, cellulose has poor compatibility with oily solvents and requires complex chemical modification.
Cellulose is pre-crosslinked and modified by co-reactant to introduce hydrophobic groups on the surface of cellulose, cellulose ester derivatives are prepared, and impurities are removed by washing-filtration process. A high-concentration cellulose oil solution is prepared by using a zirconium bead high-speed disperser.
It significantly improves the compatibility of cellulose with oily solvents, reduces impurity content, simplifies the dispersion process, enables stable dispersion and industrial production of high-concentration solutions, and is suitable for demanding applications such as lithium battery separators.
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Figure CN121779583A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of fiber material preparation technology, and more specifically, to a cellulose ester derivative, a high-concentration fiber oily solution, and a method for preparing the same. Background Technology
[0002] Nanofibers, due to their high specific surface area, excellent mechanical properties, and tunable functionality, are in high demand in fields such as composite material reinforcement and coating performance modification. Oily nanofiber solutions, with their compatibility with non-polar substrates and excellent water resistance after coating, have irreplaceable application advantages in demanding applications such as lithium battery separator coating. However, the preparation process of high-concentration oily nanofiber solutions still faces the following key problems in current technologies: 1. Nanofibers are prone to entanglement and aggregation in high-concentration systems, making it difficult to form a long-term stable dispersion solution; 2. The dispersion process consumes a large amount of organic solvent, which not only significantly increases production costs but also poses environmental and safety hazards due to solvent evaporation; 3. Natural nanofibers such as cellulose, due to their high molecular polarity, have poor compatibility with oily solvents, requiring complex chemical modification to achieve stable dispersion, which increases the complexity of the process and may also damage the original microstructure and properties of the fibers.
[0003] To address the aforementioned technical challenges, there is an urgent need in this field to develop a simple process for preparing an oily solution of nanofibers with excellent dispersion stability. By optimizing the raw material ratio and dispersion process parameters, the solution dispersion stability and application performance can be improved while reducing the cost and environmental impact of industrial production. Summary of the Invention
[0005] The purpose of this application is to provide a cellulose ester derivative and its preparation method, which can fundamentally solve the technical problem that natural cellulose is prone to agglomeration in non-polar solvents due to its high polarity.
[0006] Another objective of this application is to provide a high-concentration fibrous oily solution that has the advantage of being stable and not separating.
[0007] To solve the above-mentioned technical problems, the technical solution adopted in this application is as follows: On the one hand, this application provides a method for preparing a cellulose ester derivative, comprising the following steps: S1. Add cellulose, co-reactant and catalyst to an aprotic solvent, heat and stir until homogeneous to obtain a mixture; S2. The mixture is washed, filtered and dried to obtain the cellulose ester derivative; The molar ratio of cellulose, co-reactant and catalyst is 10:(10-20):(1-5).
[0008] On the other hand, this application provides a cellulose ester derivative prepared by the above method.
[0009] On the other hand, this application provides a high-concentration cellulose oily solution, which is obtained by adding the cellulose ester derivative prepared above into a non-polar solvent and dispersing it by stirring.
[0010] Compared with the prior art, the embodiments of this application have at least the following advantages or beneficial effects: 1. This application pre-crosslinks cellulose by using a co-reactant. The active groups of the co-reactant react with the hydroxyl groups on the cellulose molecular chain in a covalent reaction, thereby introducing hydrophobic groups onto the fiber surface and preparing modified cellulose, i.e., cellulose ester derivatives. This significantly improves its compatibility with oily solvents and fundamentally solves the technical problem that natural cellulose is prone to agglomeration in non-polar solvents due to its high polarity.
[0011] 2. This application can effectively remove unreacted co-reactants and residual catalysts from the reaction system through a washing-filtration process, significantly reducing the impurity content of the final solution, making the product suitable for applications with stringent requirements for raw material purity, such as lithium battery separators; a high-concentration cellulose oily solution can be obtained by dispersing the prepared cellulose ester derivative in a non-polar solvent. The dispersion process adopts a high-speed zirconium bead dispersion process, which does not require complex equipment or special process conditions, is simple to operate, and is easy to achieve industrial mass production. Attached Figure Description
[0012] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.
[0013] Figure 1 The infrared spectra of each experimental group in Experiment Example 1 of this application are shown in the comparison diagram. Figure 2 This is a SEM image of bacterial cellulose, the raw material used in Experimental Example 2 of this application. Figure 3 The above are the SEM test results of the cellulose ester derivatives obtained by modifying cellulose with diphenylmethane diisocyanate in Example 1 of Experimental Example 2 of this application; Figure 4 The above are the SEM test results of the cellulose ester derivatives obtained by modifying cellulose with toluene diisocyanate in Example 3 of Experimental Example 2 of this application; Figure 5 The image shows the actual product of the high-concentration fiber oily solution prepared in each experimental group in Experiment Example 3 after standing at 25°C for 12 hours. Detailed Implementation
[0014] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.
[0015] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present application will now be described in detail with reference to specific embodiments.
[0016] A method for preparing a cellulose ester derivative includes the following steps: S1. Add cellulose, co-reactant and catalyst to an aprotic solvent, heat and stir until homogeneous to obtain a mixture; S2. The mixture is washed, filtered and dried to obtain the cellulose ester derivative; The molar ratio of cellulose, co-reactant and catalyst is 10:(10-20):(1-5).
[0017] In some embodiments of this application, the cellulose mentioned above includes at least one of sugarcane cellulose, cassava cellulose, rice straw cellulose, corn straw cellulose, lignocellulose, cotton cellulose, flax cellulose, ramie cellulose, hydroxypropyl cellulose, carboxymethyl cellulose, bacterial cellulose, microcrystalline cellulose, regenerated cellulose, and nanocellulose.
[0018] In some embodiments of this application, the co-reactant includes at least one selected from toluene isocyanate, toluene diisocyanate, diphenylmethane diisocyanate, ethylene oxide, propylene oxide, glycidyl ether, epichlorohydrin, acetic acid, propionic acid, acetic anhydride, phthalic anhydride, maleic anhydride, acetyl chloride, benzoyl chloride, diethyl carbonate, isocyanurate, toluene sulfonate, and phosphorus oxychloride.
[0019] In some embodiments of this application, the catalyst includes at least one of stannous octoate, tributyltin chloride, dibutyltin dilaurate, monobutyltin oxide, p-toluenesulfonic acid, zinc chloride, tetrabutyl titanate, pyridine, triethylamine, N-methylimidazolium, sodium carbonate, sodium hydroxide, dimethylaminopyridine, aluminum trichloride, and dioctyltin dilaurate.
[0020] In some embodiments of this application, the aforementioned aprotic solvent includes at least one of xylene, cyclohexane, dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, dimethyl sulfoxide, tetrahydrofuran, and propylene carbonate.
[0021] In some embodiments of this application, the heating and stirring temperature is 40-100°C and the time is 6-30 hours; the S2 washing step uses the aprotic solvent from the S1 step, and the number of washing cycles is 3-5.
[0022] A cellulose ester derivative prepared by the above method.
[0023] A high-concentration cellulose oily solution is obtained by adding the cellulose ester derivative prepared above to a non-polar solvent, followed by stirring, dispersion, and redispersion.
[0024] In some embodiments of this application, the non-polar solvent includes at least one of toluene, ethylbenzene, pseudotrimethylbenzene, cyclohexane, n-hexane, liquid paraffin, gasoline, carbon tetrachloride, and diethyl ether; the solid content of the high-concentration fibrous oily solution is ≥2wt%.
[0025] In some embodiments of this application, the above-mentioned stirring and dispersing is carried out by at least one of grinding, ball milling and high-speed dispersing; the high-speed dispersing machine has a rotation speed of 1000-8000 rpm.
[0026] The features and performance of this application will be further described in detail below with reference to the embodiments. Example 1
[0027] 8g of bacterial cellulose, 14g of diphenylmethane diisocyanate, and 0.5g of triethylamine were added to 300ml of xylene and stirred at 65℃ for 24h. The mixture was then washed three times with xylene and filtered. Finally, it was dried at 60℃ for 24h to obtain modified bacterial cellulose (cellulose ester derivative).
[0028] Take 5g of the modified bacterial cellulose, add 110g of pseudotrimethylbenzene, stir and disperse, then transfer to a high-speed disperser equipped with zirconium beads and disperse at 1600 rpm to obtain a high-concentration cellulose oily solution. Example 2
[0029] 8g of bacterial cellulose, 7g of m-toluene isocyanate, and 0.5g of triethylamine were added to 300ml of xylene and stirred at 65℃ for 24h. The mixture was then washed three times with xylene and filtered. Finally, it was dried at 60℃ for 24h to obtain modified bacterial cellulose (cellulose ester derivative). Take 5g of modified bacterial cellulose, add 110g of pseudotrimethylbenzene, stir and disperse, then transfer to a high-speed disperser equipped with zirconium beads and disperse at 1700 rpm to obtain a high-concentration nanocellulose oily solution. Example 3
[0030] 8g of bacterial cellulose, 11g of toluene diisocyanate (TDI), and 0.5g of stannous octoate were added to 300ml of xylene. The mixture was stirred at 70℃ for 24h, then washed three times with xylene and filtered. The mixture was dried at 60℃ for 24h to obtain modified bacterial cellulose (cellulose ester derivative). Take 5g of modified bacterial cellulose, add 110g of pseudotrimethylbenzene, stir and disperse, then transfer to a high-speed disperser equipped with zirconium beads and disperse at 2000 rpm to obtain a high-concentration cellulose oil solution. Example 4
[0031] 10g of nanocellulose, 12g of diphenylmethane diisocyanate, and 0.5g of pyridine were added to 300ml of xylene. The mixture was stirred at 60℃ for 30h, then washed three times with xylene and filtered. The mixture was dried at 60℃ for 24h to obtain modified nanocellulose (cellulose ester derivative). Take 5g of modified nanocellulose, add 110g of pseudotrimethylbenzene, stir and disperse, then transfer to a high-speed disperser equipped with zirconium beads and disperse at 1600 rpm to obtain a high-concentration cellulose oil solution. Example 5
[0032] 10g of nanocellulose, 11g of toluene diisocyanate, and 0.5g of triethylamine were added to 300ml of xylene. The mixture was stirred at 75℃ for 12h, then washed three times with xylene and filtered. The mixture was dried at 60℃ for 24h to obtain modified nanocellulose (cellulose ester derivative). Take 5g of modified nanocellulose, add 110g of pseudotrimethylbenzene, stir and disperse, then transfer to a high-speed disperser equipped with zirconium beads and disperse at 1600 rpm to obtain a high-concentration cellulose oil solution.
[0033] Comparative Example 1
[0034] This comparative example follows the same steps as Example 1, except that it does not use a co-reactant and catalyst, but only bacterial cellulose. Specifically: 8g of bacterial cellulose was added to 300ml of xylene and stirred at 65℃ for 24h. The mixture was then washed three times with xylene and filtered. Finally, it was dried at 60℃ for 24h to obtain modified bacterial cellulose (cellulose ester derivative). Take 5g of modified bacterial cellulose, add 110g of pseudotrimethylbenzene, stir and disperse, then transfer to a high-speed disperser equipped with zirconium beads and disperse at 1600 rpm to obtain a high-concentration cellulose oily solution.
[0035] Experimental Example 1
[0036] Infrared spectroscopy was performed on the cellulose ester derivatives obtained in Examples 1, 2, and 3, as well as the raw material bacterial cellulose. The results are as follows: Figure 1 As shown.
[0037] Wherein BC represents the infrared spectrum results of bacterial cellulose. BC-MDI represents the infrared spectrum results of the cellulose ester derivative obtained by modifying cellulose with diphenylmethane diisocyanate in Example 1. BC-mTI represents the infrared spectrum results of the cellulose ester derivative obtained by modifying cellulose with m-toluene isocyanate in Example 2. BC-TDI represents the infrared spectrum results of the cellulose ester derivative obtained by modifying cellulose with toluene diisocyanate in Example 3 of this invention.
[0038] Depend on Figure 1 It can be seen from the comparison of the infrared characteristic peaks of bacterial cellulose and the modified product that an esterification reaction has occurred. Specifically, the characteristic peaks of bacterial cellulose at 3300-3500 cm⁻¹ are... - The broad, intense peak at ¹ (due to the stretching vibration of -OH) shows a significant decrease in intensity in the corresponding region of the modified product, indicating that -OH participates in the reaction. Meanwhile, the peak intensity at 1700-1750 cm⁻¹ is also significant. - A new peak appears at ¹ (corresponding to the stretching vibration of C=O in carbamates), and a peak also appears at 1500-1600 cm⁻¹. - The appearance of the NH bending vibration peak at position ¹ proves that bacterial cellulose and isocyanate have formed an esterification product.
[0039] The slight differences in characteristic peak shifts observed in this experimental example using different co-reactants indicate that the substituent structures of different isocyanates differ. This demonstrates that the structure of the modified product can be controlled by adjusting the type of co-reactant. This invention can be used for the preparation of various cellulose ester derivatives.
[0040] Experiment Example 2
[0041] The raw material bacterial cellulose and the cellulose ester derivatives obtained in Examples 1 and 3 were subjected to SEM testing, such as... Figures 2-4 As shown.
[0042] Figure 2 The image shows an SEM image of the raw material bacterial cellulose. As can be seen, the bacterial cellulose used in this invention exhibits a three-dimensional porous network structure with interwoven nanofibers, which enables the fibers to disperse excellently in oily solutions.
[0043] Figure 3 The figure shows the SEM test results of the cellulose ester derivative obtained by modifying cellulose with diphenylmethane diisocyanate in Example 1. As can be seen from the figure, the bacterial cellulose ester derivative modified with diphenylmethane diisocyanate forms a hydrophobic aggregate structure, with a roughened surface and interfacial compatibility adapted to the oil phase, which significantly improves the dispersion concentration of the derivative in oily solutions.
[0044] Figure 4The figures show the SEM results of the cellulose ester derivatives obtained by modifying cellulose with toluene diisocyanate in Example 3. As can be seen from the figures, the toluene diisocyanate-modified cellulose ester derivatives used in this invention exhibit a porous, aggregated fibrous aggregate morphology: the original nanoscale filamentous structure of the fibers is cross-linked and entangled after modification, forming blocky aggregates with multi-level pores. The hydrophobic groups introduced by toluene diisocyanate synergistically work with the rough interface of the aggregates to significantly reduce the interfacial tension between the fibers and the oily medium, ensuring that the high-concentration fiber oily solution remains homogeneous and stable at room temperature, thus avoiding the problem of cellulose easily separating and settling in the oil phase.
[0045] Experimental Example 3
[0046] The high-concentration fiber oily solutions prepared in Examples 1-3 and Comparative 1 were allowed to stand at 25°C for 12 hours. The test results are as follows. Figure 5 As shown in the figure. (a) represents Comparative Example 1, (b) represents Example 1, (c) represents Example 2, and (d) represents Example 3.
[0047] As shown in the figure, the experimental group solutions of Examples 1-3 all maintained a uniform milky white appearance, without layering, precipitation or exudation. This indicates that the high-concentration cellulose oily solution prepared in the examples of this application has excellent storage stability under room temperature conditions.
[0048] In Comparative Example 1, since no isocyanate or catalyst was added, the bacterial cellulose treated only by soaking in xylene still retained a large number of hydroxyl groups on its surface, resulting in strong intermolecular hydrogen bonding and extremely poor solubility in the hydrophobic solvent pseudotrimethylbenzene. The solution prepared in Comparative Example 1 contained clearly visible fiber aggregates, and after standing at 25°C for 12 hours, significant stratification occurred: the upper layer was clear pseudotrimethylbenzene solvent, and the lower layer was a dense fiber precipitate, indicating severely insufficient dispersion uniformity.
[0049] The embodiments described above are some, but not all, of the embodiments of this application. The detailed description of the embodiments of this application is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.
Claims
1. A method for preparing a cellulose ester derivative, characterized in that, Includes the following steps: S1. Add cellulose, co-reactant and catalyst to an aprotic solvent, heat and stir until homogeneous to obtain a mixture; S2. The mixture is washed, filtered and dried to obtain the cellulose ester derivative; The molar ratio of cellulose, co-reactant and catalyst is 10:(10-20):(1-5).
2. The method for preparing a cellulose ester derivative according to claim 1, characterized in that, The cellulose includes at least one of sugarcane cellulose, cassava cellulose, rice straw cellulose, corn straw cellulose, lignocellulose, cotton cellulose, flax cellulose, ramie cellulose, hydroxypropyl cellulose, carboxymethyl cellulose, bacterial cellulose, microcrystalline cellulose, regenerated cellulose, and nanocellulose.
3. The method for preparing a cellulose ester derivative according to claim 1, characterized in that, The co-reactants include at least one of toluene isocyanate, toluene diisocyanate, diphenylmethane diisocyanate, ethylene oxide, propylene oxide, glycidyl ether, epichlorohydrin, acetic acid, propionic acid, acetic anhydride, phthalic anhydride, maleic anhydride, acetyl chloride, benzoyl chloride, diethyl carbonate, isocyanurate, toluene sulfonate, and phosphorus oxychloride.
4. The method for preparing a cellulose ester derivative according to claim 1, characterized in that, The catalyst comprises at least one of the following: stannous octoate, tributyltin chloride, dibutyltin dilaurate, monobutyltin oxide, p-toluenesulfonic acid, zinc chloride, tetrabutyl titanate, pyridine, triethylamine, N-methylimidazolium, sodium carbonate, sodium hydroxide, dimethylaminopyridine, aluminum trichloride, and dioctyltin dilaurate.
5. The method for preparing a cellulose ester derivative according to claim 1, characterized in that, The aprotic solvent includes at least one of xylene, cyclohexane, dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, dimethyl sulfoxide, tetrahydrofuran, and propylene carbonate.
6. The method for preparing a cellulose ester derivative according to claim 1, characterized in that, The heating and stirring temperature is 40-100℃, and the time is 6-30h; the S2 washing step uses the aprotic solvent from the S1 step, and the washing is performed 3-5 times.
7. A cellulose ester derivative, characterized in that, It is prepared by the method described in any one of claims 1-6.
8. A high-concentration fiber-based oily solution, characterized in that, The cellulose ester derivative of claim 7 is added to a nonpolar solvent and dispersed by stirring to obtain a high-concentration cellulose oily solution.
9. The method for preparing a cellulose ester derivative according to claim 8, characterized in that, The nonpolar solvent includes at least one of toluene, ethylbenzene, pseudotrimethylbenzene, cyclohexane, n-hexane, liquid paraffin, gasoline, carbon tetrachloride, and diethyl ether; the solid content of the high-concentration fiber oily solution is ≥2wt%.
10. A method for preparing a cellulose ester derivative according to claim 8, characterized in that, The stirring and dispersing is performed using at least one of grinding, ball milling, and high-speed dispersing; the high-speed dispersing machine operates at a speed of 1000-8000 rpm.