Kaolin powder modification treatment method and application thereof

Abstract

The invention relates to the field of kaolin modification, and discloses a kaolin powder modification treatment method and application thereof, the method comprises the following steps: mixing diatomite powder with kaolin powder; medium mixing is conducted, 3-aminopropyltriethoxysilane and ethyl alcohol are mixed, and the concentration of the ethyl alcohol is 90%-95%; post-mixing: mixing the polyether polyol phosphate ester with deionized water; final mixing: mixing the primary mixture, the medium mixture and the post-mixture, then adding sodium citrate and polyvinylpyrrolidone, and uniformly mixing; fermenting, namely adding cellulase and succinic acid monoester into a mixture obtained by final mixing, uniformly stirring, and standing for fermenting; and after fermentation, drying and crushing to obtain the modified kaolin powder. After 3-aminopropyltriethoxysilane and polyether polyol phosphate are adopted, amino and phosphate functional groups are chemically bonded, silicon-oxygen bonds of silane react with hydroxyl groups of kaolin to generate silicon-oxygen bridges, and meanwhile, phosphate groups interact with metal ions, so that dispersity and compatibility are improved.

Description

Technical Field

[0001] The present invention relates to the field of kaolin modification, specifically to a method for modifying kaolin powder and its application. Background Art

[0002] Kaolin, as an important industrial raw material, is widely used in many fields such as coatings, plastics, rubbers, ceramics, and papers. With the continuous growth of industrial demands, the performance requirements for kaolin are also getting higher and higher, especially in terms of dispersibility, specific surface area, porosity, etc. Therefore, researchers have been committed to modifying kaolin to improve its performance in various applications. Traditional kaolin modification methods mostly adopt physical or chemical methods such as surface coating and surface grafting, but these methods often face the problem of unstable effects. In addition, the surface of kaolin often contains organic impurities and metal ions, which not only reduce the specific surface area and porosity of kaolin, but also affect its compatibility and dispersibility in polymers. Summary of the Invention

[0003] Aiming at the deficiencies of the prior art, the present invention provides a method for modifying kaolin powder and its application, which solves the problems that the traditional methods are complex in process and high in cost, and the modification effect is unstable; the organic impurities and metal ions on the surface of kaolin cannot be effectively removed, resulting in insufficient specific surface area, porosity and dispersibility, and thus affecting its compatibility in polymers.

[0004] To achieve the above objectives, the present invention is realized through the following technical solutions: A method for modifying kaolin powder, comprising the following steps: Prepare a modifier, and the modifier comprises the following components in parts by mass: 3-aminopropyltriethoxysilane: 5-15 parts, polyether polyol phosphate ester: 3-12 parts, cellulase: 1-5 parts, succinic acid monoester: 2-8 parts, ethanol: 10-25 parts, deionized water: 20-40 parts, polyvinylpyrrolidone: 1-5 parts, sodium citrate: 0.5-3 parts, diatomite: 2-6 parts, kaolin: 80-120 parts; Among them, 3-aminopropyltriethoxysilane: It is a surfactant with amphiphilic affinity characteristics. One end of the ethoxy group can form a covalent bond with the hydroxyl group on the surface of kaolin, improving surface activity and the compatibility of the organic phase; the amino group (-NH2) at the other end can enhance polar interactions, improve the binding force with the polymer matrix, and make kaolin more easily dispersed in the organic matrix.

[0005] Polyether polyol phosphate ester: This component can reduce the surface energy of kaolin, improve wettability, and enhance the stability between particles through the phosphate group (-PO4), prevent agglomeration, and improve the fluidity of modified kaolin.

[0006] Cellulase: It is a biological enzyme that can selectively degrade certain organic impurities during anaerobic fermentation. At the same time, it enhances the porous structure on the particle surface, increases the specific surface area, and promotes the absorption of other modifiers.

[0007] Succinic acid monoester: This additive can adjust the surface charge distribution of kaolin, improve its affinity with organic substances, and thus enhance its dispersion performance in resins or rubbers.

[0008] Ethanol: As an organic solvent, it promotes the uniform mixing of modifiers and helps with the hydrolysis and cross-linking reactions of silane coupling agents, enabling them to better adhere to the surface of kaolin.

[0009] Deionized water: It provides the necessary reaction medium and avoids the influence of metal ions on the modification effect.

[0010] Polyvinylpyrrolidone: This polymer can enhance the suspension stability of particles through intermolecular hydrogen bonding and improve the fluidity of the final product.

[0011] Sodium citrate: It is used to adjust the pH value, prevent agglomeration during the modification process, and can chelate impurity metal ions to improve the stability of the system.

[0012] Diatomite: As a carrier and filler, it improves the mixing uniformity, optimizes the distribution of modifiers, and regulates the porosity of the final product.

[0013] Kaolin: The matrix material, whose dispersibility, fluidity are improved and its adhesion to polymers is enhanced after modification.

[0014] Pre-treat the kaolin, and the pre-treatment includes crushing, sieving and drying, and after completion, kaolin powder is obtained; Primary mixing: First, crush, sieve and dry diatomite to obtain diatomite powder, and then mix the diatomite powder with the kaolin powder; Intermediate mixing: Mix 3-aminopropyltriethoxysilane with ethanol, and the ethanol concentration is 90 - 95%; Post-mixing: Mix polyether polyol phosphate with deionized water; Final mixing: Mix the products obtained from primary mixing, intermediate mixing and post-mixing, and then add sodium citrate and polyvinylpyrrolidone and mix evenly; Fermentation: Add cellulase and succinic acid monoester to the product obtained from final mixing, stir evenly and then let it stand for fermentation; Drying: Dry and crush the fermented kaolin to obtain modified kaolin powder.

[0015] Preferably, in the pre-treatment, the particle diameter of the kaolin powder after crushing and sieving is 1 - 5 μm, and the drying is carried out at a temperature of 80 - 120 °C for 2 - 4 h.

[0016] The main component of kaolin is hydrated aluminosilicate (Al2Si2O5(OH)4), and its surface has a large number of hydroxyl groups. Crushing can break the lamellar structure, expose more active sites, and improve the adsorption capacity of subsequent modifiers. Drying helps to remove free water, reduce the hydrogen bond interaction between particles, and thus improve fluidity.

[0017] Preferably, in the primary mixing, the diameter of the diatomite particles after crushing and sieving is 1 - 5 μm, the drying is carried out at a temperature of 100 - 120 °C for 2 - 4 h, and the kaolin powder and the diatomite powder are mixed at a rotation speed of 500 - 1000 rpm for 10 - 30 min.

[0018] Diatomite is a porous siliceous material with excellent adsorption properties. After mixing it with kaolin, it can adjust the electrostatic interaction between particles, improve the dispersibility, and promote the uniform adsorption of modifiers in the subsequent modification process.

[0019] Preferably, in the intermediate mixing, 3 - aminopropyltriethoxysilane and ethanol are mixed at a rotation speed of 300 - 500 rpm for 15 - 20 min.

[0020] The silane coupling agent undergoes partial hydrolysis in an ethanol medium: Si(OR)3 + H2O → Si(OH)3 + ROH; The generated silanol (Si - OH) can further condense to form a cross - linked network, which helps to enhance its binding strength with kaolin.

[0021] Preferably, in the final mixing, polyether polyol phosphate and deionized water are mixed at a rotation speed of 450 - 600 rpm for 18 - 30 min.

[0022] The phosphate ester group (-PO4) of polyether polyol phosphate can form a complex with the aluminum ions on the surface of kaolin, thereby enhancing its stability, while reducing the surface energy, preventing agglomeration, and improving fluidity.

[0023] Preferably, in the final blending, the products obtained from the primary mixing, intermediate mixing, and final mixing are mixed at a rotation speed of 600 - 900 rpm for 30 - 40 min. After adding sodium citrate and polyvinylpyrrolidone, they are mixed at a rotation speed of 700 - 900 rpm for 40 - 50 min.

[0024] The purpose of this stage is to form a uniform modification system, where sodium citrate helps to adjust the pH value, and polyvinylpyrrolidone can form a stable colloidal structure to improve the dispersibility.

[0025] Preferably, after adding cellulase and succinic acid monoester, mix them under the condition of 300-500 rpm for 40-70 min, and then carry out anaerobic fermentation for 48-120 h at a temperature of 25-35 °C. After the fermentation is completed, dry it at 80-120 °C for 120-240 min to remove excess moisture, and obtain modified kaolin powder after pulverization.

[0026] Cellulase degrades organic impurities during the fermentation process, improves the purity of kaolin, and at the same time increases the surface porosity, making it easier for the modifier to adsorb. The anaerobic condition can prevent oxidation side reactions and improve the stability of the final product.

[0027] The kaolin powder modified by a kaolin powder modification treatment method is applied in the fields of plastics, rubbers, ceramics and coatings.

[0028] The present invention provides a kaolin powder modification treatment method and its application. It has the following beneficial effects: 1. In the present invention, by using 3-aminopropyltriethoxysilane and polyether polyol phosphate, the amino group of 3-aminopropyltriethoxysilane undergoes chemical bonding with the functional groups of polyether polyol phosphate, and the silane molecule reacts with the hydroxyl groups on the surface of kaolin through its siloxane bond, thereby forming a stable siloxane bridging structure. Moreover, the phosphate groups of polyether polyol phosphate interact with the metal ions on the surface of kaolin, further enhancing the dispersibility of kaolin and its compatibility in polymers.

[0029] 2. In the present invention, by introducing cellulase, using its unique biocatalytic ability to degrade some organic impurities on the surface of kaolin, the specific surface area and porosity of kaolin are enhanced. And cellulase catalyzes the hydrolysis of the sugar chain structure in cellulose or other organic substances to produce smaller molecular segments and remove the attached impurities on the surface. This process not only helps to clean the surface of kaolin, but also increases the active sites on its surface, thereby enhancing the binding force between the modifier and kaolin.

[0030] 3. In the present invention, by interacting succinic acid monoester with cellulase, when cellulase hydrolyzes organic impurities, the carboxylic acid groups of succinic acid monoester can undergo complexation reactions with metal ions such as aluminum and silicon on the surface of kaolin, further improving the surface structure of kaolin. Not only are the organic impurities on the surface of kaolin effectively removed, but also the generation of a surface porous structure is promoted, increasing the specific surface area of kaolin and providing more active sites for the adsorption of subsequent modifiers. Description of the Drawings

[0031] Figure 1 It is a schematic flow chart of the method of the present invention. Detailed Embodiments

[0032] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings in the specification of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0033] To better understand the present invention, the above content will be described in detail below in conjunction with specific embodiments.

[0034] Please refer to the attached Figure 1 : Example 1: Components: 3-aminopropyltriethoxysilane: 10 parts, polyether polyol phosphate: 8 parts, cellulase: 3 parts, succinic acid monoester: 5 parts, ethanol: 18 parts, deionized water: 10 parts, polyvinylpyrrolidone: 3 parts, sodium citrate: 2 parts, diatomaceous earth: 4 parts, kaolin: 100 parts; Modification steps: Pretreatment: Crush, sieve, and dry kaolin (at 100 °C for 3 h) to obtain kaolin powder, and the particle diameter of the kaolin powder is 3 μm; Initial mixing: Crush, sieve, and dry diatomaceous earth (at 110 °C for 3 h) to obtain diatomaceous earth powder, and the particle diameter of the diatomaceous earth powder is 3 μm, and mix the diatomaceous earth powder and kaolin powder at 800 rpm for 20 min; Intermediate mixing: Mix 3-aminopropyltriethoxysilane with ethanol, and the mixing conditions are (mixing at 400 rpm for 18 min), and the ethanol concentration is 95%; Final mixing: Mix the products obtained from initial mixing, intermediate mixing, and final mixing at 800 rpm for 35 min, add sodium citrate and polyvinylpyrrolidone, and then continue to mix at 800 rpm for 45 min; Final mixing: Mix the products obtained from initial mixing, intermediate mixing, and final mixing at 800 rpm for 35 min, add sodium citrate and polyvinylpyrrolidone, and then continue to mix at 800 rpm for 45 min; Fermentation: Add cellulase and succinic acid monoester and mix at 400 rpm for 50 min, and then ferment anaerobically at 30 °C for 84 h; Drying: After fermentation, dry at 100 °C for 200 min to remove excess moisture, and obtain modified kaolin powder after pulverization.

[0035] Example 2: Components: 3-aminopropyltriethoxysilane: 5 parts, polyether polyol phosphate: 3 parts, cellulase: 1 part, succinic acid monoester: 2 parts, ethanol: 10 parts, deionized water: 20 parts, polyvinylpyrrolidone: 1 part, sodium citrate: 0.5 part, diatomite: 2 parts, kaolin: 80 parts; Modification steps: Pretreatment: Crush, sieve and dry kaolin (80 °C, 2 h) to obtain kaolin powder, and the particle diameter of the kaolin powder is 1 μm; Primary mixing: Crush, sieve and dry diatomite (100 °C, 2 h) to obtain diatomite powder, and the particle diameter of the diatomite powder is 1 μm, and mix the diatomite powder and kaolin powder at 500 rpm for 10 min; Intermediate mixing: Mix 3-aminopropyltriethoxysilane with ethanol, and the mixing conditions are (mixing at 300 rpm for 15 min), and the ethanol concentration is 95%; Post-mixing: Mix polyether polyol phosphate with deionized water, and the mixing conditions are: mixing at 450 rpm for 18 min; Final mixing: Mix the products obtained from primary mixing, intermediate mixing and post-mixing at 600 rpm for 30 min, add sodium citrate and polyvinylpyrrolidone, and then continue to mix at 700 rpm for 40 min; Fermentation: Add cellulase and succinic acid monoester and mix at 300 rpm for 40 min, and then carry out anaerobic fermentation at 25 °C for 48 h; Drying: After fermentation, dry at 80 °C for 120 min to remove excess water, and obtain modified kaolin powder after crushing.

[0036] Example 3: Components: 3-aminopropyltriethoxysilane: 15 parts, polyether polyol phosphate: 12 parts, cellulase: 5 parts, succinic acid monoester: 8 parts, ethanol: 25 parts, deionized water: 40 parts, polyvinylpyrrolidone: 5 parts, sodium citrate: 3 parts, diatomite: 6 parts, kaolin: 120 parts; Modification steps: Pretreatment: Crush, sieve and dry kaolin (120 °C, 4 h) to obtain kaolin powder, and the particle diameter of the kaolin powder is 5 μm; Primary mixing: Crush, sieve and dry diatomite (120 °C, 4 h) to obtain diatomite powder, and the particle diameter of the diatomite powder is 5 μm, and mix the diatomite powder and kaolin powder at 1000 rpm for 30 min; Intermediate mixing: Mix 3-aminopropyltriethoxysilane with ethanol, and the mixing conditions are (mixing at 500 rpm for 20 min), and the ethanol concentration is 95%; Post - mixing: Mix polyether polyol phosphate ester with deionized water under the conditions: mix at 600 rpm for 30 min; Final - mixing: The products obtained from preliminary - mixing, intermediate - mixing and post - mixing are mixed at 900 rpm for 40 min. After adding sodium citrate and polyvinylpyrrolidone, continue to mix at 900 rpm for 50 min; Fermentation: After adding cellulase and monoesters of succinic acid, mix at 500 rpm for 70 min, and then ferment anaerobically at 35 °C for 120 h; Drying: After the fermentation is completed, dry at 120 °C for 240 min to remove excess moisture, and obtain modified kaolin powder after pulverization.

[0037] Comparative Example 1: Based on Example 1, the differences are: without 3 - aminopropyltriethoxysilane, without the intermediate - mixing step, and add ethanol together with sodium citrate and polyvinylpyrrolidone to the final - mixing, and the rest are the same.

[0038] Comparative Example 2: Based on Example 2, the differences are: 4 parts of 3 - aminopropyltriethoxysilane, and the rest are the same.

[0039] Comparative Example 3: Based on Example 3, the differences are: 16 parts of 3 - aminopropyltriethoxysilane, and the rest are the same.

[0040] Comparative Example 4: Based on Example 1, the differences are: without polyether polyol phosphate ester, without the post - mixing step, and add deionized water together with sodium citrate and polyvinylpyrrolidone to the final - mixing, and the rest are the same.

[0041] Comparative Example 5: Based on Example 2, the differences are: 2 parts of polyether polyol phosphate ester, and the rest are the same.

[0042] Comparative Example 6: Based on Example 3, the differences are: 13 parts of polyether polyol phosphate ester, and the rest are the same.

[0043] Comparative Example 7: Based on Example 1, the differences are: without polyether polyol phosphate ester and 3 - aminopropyltriethoxysilane, without the intermediate - mixing and post - mixing steps, and add deionized water and ethanol together with sodium citrate and polyvinylpyrrolidone to the final - mixing, and the rest are the same.

[0044] Comparative Example 8: Based on Example 1, the differences are: without cellulase, without the fermentation step, and the rest are the same.

[0045] Comparative Example 9: Based on Example 2, the difference is that: 0.5 part of cellulase, and the rest are the same.

[0046] Comparative Example 10: Based on Example 3, the difference is that: 6 parts of cellulase, and the rest are the same.

[0047] Comparative Example 11: Based on Example 1, the difference is that: no succinic acid monoester, no fermentation step, and the rest are the same.

[0048] Comparative Example 12: Based on Example 2, the difference is that: 1 part of succinic acid monoester, and the rest are the same.

[0049] Comparative Example 13: Based on Example 3, the difference is that: 9 parts of succinic acid monoester, and the rest are the same.

[0050] Comparative Example 14: Based on Example 1, the difference is that: no succinic acid monoester and succinic acid monoester, no fermentation step, and the rest are the same.

[0051] Experiment 1: Experiment Purpose The purpose of this experiment is to explore the effects of 3-aminopropyltriethoxysilane and polyether polyol phosphate in the modification of kaolin. Through different modification processes and experimental conditions, analyze the particle size distribution, interfacial compatibility, thermal stability, dispersibility and chemical structure changes of the modified kaolin, and further evaluate the improvement effects of these modifiers on the properties of kaolin.

[0052] Experimental Steps 1. Sample Setting: Select Examples 1-3 and Comparative Examples 1-7 as samples.

[0053] 2. Test Items and Experimental Basis: Particle Size Distribution (Laser Particle Size Analyzer): Use a laser particle size analyzer to measure the particle size distribution of the modified samples and evaluate the uniformity of the particle size.

[0054] Interfacial Compatibility (Contact Angle Measurement): Evaluate the hydrophilic and hydrophobic changes of the modified samples through contact angle measurement.

[0055] Thermal Stability (TGA / DSC): Use thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) to test the thermal stability and thermal decomposition characteristics of the modified materials.

[0056] Dispersibility Test (Zeta Potential): Measure the dispersibility of the samples in different solvents and evaluate the dispersibility changes of the modified kaolin.

[0057] Chemical structure changes (FTIR / XPS): Fourier Transform Infrared Spectroscopy (FTIR) and X-ray Photoelectron Spectroscopy (XPS) techniques were used to analyze the chemical bonding between the modifier and kaolin to determine the modification effect.

[0058] 3. The experimental data are recorded as shown in Table 1: Table 1: Performance test results of modified kaolin 4. Experimental summary Particle size distribution (particle size) The particle size of Example 1 is 3.2 μm, which is smaller than that of Comparative Example 1 (4.5 μm) and Comparative Example 2 (3.0 μm), and is relatively uniform. The particle size of Example 1 shows an ideal balance, neither too small nor too large, suitable for a wide range of application scenarios.

[0059] The particle size of Example 2 is 1.8 μm, which is small, but may be slightly worse in terms of dispersibility because small particles tend to agglomerate. In contrast, the particle size of Example 1 is more ideal and is more conducive to the stable dispersion of kaolin.

[0060] The particle size of Example 3 is relatively large, reaching 5.1 μm, which indicates that its particles may be relatively coarse and may be limited in terms of dispersibility. However, the advantage of its large particle size is that it can provide strong thermal stability.

[0061] Compared with the comparative example group, the particle size of Example 1 is 3.2 μm, showing a more uniform distribution and better performance.

[0062] Hydrophobicity (contact angle) The contact angle of Example 1 is 82°, which is significantly higher than that of Comparative Example 1 (72°) and Comparative Example 4 (70°), but slightly lower than that of Example 2 (95°) and Example 3 (90°). This indicates that the hydrophobicity of Example 1 is better than that of most of the comparative example groups and can effectively reduce the contact between water and the material surface.

[0063] The contact angle of Example 2 is as high as 95°, which is the highest among all samples, showing its very strong hydrophobicity. The high contact angle indicates that its surface can effectively repel water and is suitable for applications that require high hydrophobicity.

[0064] The contact angle of Example 3 is 90°, which is also relatively high, showing good hydrophobicity. Its performance is better than that of most of the comparative example groups, indicating that the synergistic effect of the composite modifier can effectively improve the hydrophobicity.

[0065] Compared with Comparative Example 1 (contact angle 72°) and Comparative Example 4 (contact angle 70°), the hydrophobicity of Example 1 has been significantly improved, indicating that the modification treatment effectively enhances the hydrophobicity of kaolin.

[0066] Thermal stability (thermal decomposition temperature) The thermal decomposition temperature of Example 3 is 620 °C, which is the highest among all experimental groups, showing the strongest thermal stability. This indicates that the composite modifier can effectively improve the heat resistance of kaolin and is suitable for use in high-temperature environments.

[0067] The thermal decomposition temperature of Example 1 is 600 °C, ranking second among all groups. Although slightly inferior to Example 3, it still exhibits relatively high thermal stability.

[0068] The thermal decomposition temperature of Example 2 is 580 °C, slightly lower than that of Example 1 and Example 3, indicating that its thermal stability is relatively poor, but still superior to the control group.

[0069] In contrast, the thermal stability of the control group is generally poor, especially for Control Example 4 (570 °C) and Control Example 2 (580 °C). This further proves that the combined use of 3-aminopropyltriethoxysilane and polyether polyol phosphate significantly improves the thermal stability.

[0070] Dispersion (Zeta potential) The Zeta potential of Example 1 is -28 mV, which is the highest among all experimental groups, indicating the best dispersion. A higher Zeta potential means stronger repulsive forces between kaolin particles, preventing particle aggregation and agglomeration.

[0071] The Zeta potential of Example 2 is -25 mV. Although not as good as Example 1, it still shows good dispersion. Compared with Control Example 1 (-15 mV) and Control Example 4 (-12 mV), its dispersion is significantly better.

[0072] The Zeta potential of Example 3 is -22 mV, which is also better than that of most control groups. Although its dispersion is not as good as Example 1, it is still superior to the control group.

[0073] Compared with the control group, the Zeta potential of Example 1 and Example 3 is higher, indicating that the use of the composite modifier effectively improves the stability and dispersion of the particles.

[0074] Chemical structure (FTIR and XPS analysis) The characteristic FTIR peaks of Example 1, Example 2, and Example 3 are 3400 cm -1 (-OH groups), which correspond to the functional functional groups of their surface modifiers, indicating that the modified molecules have been successfully grafted onto the surface. Through XPS analysis, significant changes in the surface chemical structure can be seen, indicating that the modifier has successfully reacted with kaolin.

[0075] The FTIR peaks of the comparative example group were relatively single, and the XPS results showed that the surface modification effect was weak, indicating that the modifier used alone failed to effectively optimize the surface properties of kaolin.

[0076] Examples 1, 2, and 3 showed superior performance in many aspects compared to Comparative Examples 1-7. Especially in terms of particle size distribution, hydrophobicity, thermal stability, dispersibility, and chemical stability, the combined use of 3-aminopropyltriethoxysilane and polyether polyol phosphate played a significant synergistic effect.

[0077] Example 1 demonstrated relatively balanced superior performance in terms of particle size, dispersibility, hydrophobicity, and thermal stability.

[0078] Example 2 exhibited extremely high hydrophobicity and was suitable for applications that require highly hydrophobic materials.

[0079] Example 3 showed the best performance in terms of thermal stability and was suitable for high-temperature application environments.

[0080] Through the comparison of these data, it can be clearly seen that the combined use of 3-aminopropyltriethoxysilane and polyether polyol phosphate significantly improved the various properties of kaolin, especially its enhanced effects in thermal stability, dispersibility, and hydrophobicity, making it show obvious advantages in various industrial applications.

[0081] Experiment 2 Experimental Purpose This experiment aimed to explore the effects of cellulase and succinic acid monoester on the modification properties of kaolin. By comparing the modification effects of each group, the improvement effects of these two components on the surface properties of kaolin were evaluated. The focus was on analyzing their action mechanisms in terms of particle size distribution, hydrophobicity, thermal stability, dispersibility, and chemical stability.

[0082] Experimental Procedures 1. Sample Setting: Examples 1-3 and Comparative Examples 8-14 were selected as samples.

[0083] 2. Test Items and Experimental Basis: Particle Size Distribution (Laser Particle Size Analyzer): The laser particle size analyzer was used to measure the particle size distribution of the modified samples to evaluate the uniformity of particle size.

[0084] Interface Compatibility (Contact Angle Measurement): The contact angle measurement was used to evaluate the changes in hydrophilicity and hydrophobicity of the modified samples.

[0085] Thermal Stability (TGA / DSC): Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) were used to test the thermal stability and thermal decomposition characteristics of the modified materials.

[0086] Dispersion test (Zeta potential): Measure the dispersion of the sample in different solvents and evaluate the change in the dispersion of the modified kaolin.

[0087] Chemical structure change (FTIR / XPS): Use Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) techniques to analyze the chemical bonding between the modifier and kaolin, and determine the modification effect.

[0088] 3. The experimental data are recorded as shown in Table 2: Table 2: Test results of the properties of modified kaolin 4. Experimental summary Particle size (μm) analysis The particle sizes of kaolin in Examples 1, 2, and 3 are 3.2 μm, 1.9 μm, and 5.3 μm, respectively.

[0089] The particle size of Comparative Example 8 is 4.8 μm, Comparative Example 9 is 3.1 μm, Comparative Example 10 is 5.0 μm, Comparative Example 11 is 4.6 μm, Comparative Example 12 is 2.8 μm, Comparative Example 13 is 5.2 μm, and Comparative Example 14 is 5.4 μm.

[0090] Analysis: Example 2 shows the smallest particle size (1.9 μm), which means that its modification effect has a greater advantage in refining the particle size, can increase the surface area of kaolin, and is beneficial to improving its performance in different industrial applications, such as catalysis, adsorption, etc.

[0091] The particle sizes of Example 1 and Example 3 are 3.2 μm and 5.3 μm, respectively. Although the particle sizes are larger, through the fermentation and modification processes, other properties of kaolin are improved.

[0092] Among Comparative Examples 8, 9, 10, 11, 12, 13, and 14, the particle sizes are generally larger, especially the particle size of Comparative Example 14 is the largest, indicating that when not fully modified (such as lacking cellulase and succinic acid monoester), the particles of kaolin do not significantly become smaller, and the modification effect is poor.

[0093] Contact angle (°) analysis The contact angles of Examples 1, 2, and 3 are 82°, 85°, and 89°, respectively.

[0094] The contact angle of Comparative Example 8 is 75°, Comparative Example 9 is 80°, Comparative Example 10 is 87°, Comparative Example 11 is 73°, Comparative Example 12 is 79°, Comparative Example 13 is 92°, and Comparative Example 14 is 76°.

[0095] Analysis: The contact angle of Example 3 is 89°, indicating that the modified kaolin has stronger hydrophobicity, showing better waterproof and water resistance properties, and is suitable for application scenarios that require good hydrophobicity.

[0096] The contact angle of Example 2 is 85°, still being relatively hydrophobic, indicating that the hydrophobicity has been improved even at lower cellulase and succinic acid monoester contents.

[0097] The contact angle of Example 1 is 82°, which is slightly inferior in comparison but still maintains good hydrophobicity.

[0098] The contact angles in Comparative Examples 8, 9, 10, 11, 12, 13, and 14 are generally low. In particular, the contact angle of Comparative Example 11 is 73°, indicating that the modification effect is significantly inferior to that of the Example group in the absence of cellulase or succinic acid monoester.

[0099] Thermal decomposition temperature (°C) analysis The thermal decomposition temperatures of Examples 1, 2, and 3 are 600 °C, 580 °C, and 620 °C respectively.

[0100] For Comparative Example 8, it is 590 °C; for Comparative Example 9, it is 590 °C; for Comparative Example 10, it is 615 °C; for Comparative Example 11, it is 570 °C; for Comparative Example 12, it is 580 °C; for Comparative Example 13, it is 625 °C; for Comparative Example 14, it is 590 °C.

[0101] Analysis: The thermal decomposition temperature of Example 3 is 620 °C, showing the highest thermal stability, indicating that the modified kaolin can withstand higher temperatures and is suitable for more severe high-temperature environments.

[0102] The thermal decomposition temperatures of Examples 1 and 2 are 600 °C and 580 °C respectively, both showing good thermal stability and being able to maintain their properties at higher temperatures.

[0103] The thermal decomposition temperature of Comparative Example 11 is the lowest (570 °C), indicating that the lack of succinic acid monoester or the fermentation step will affect the thermal stability of kaolin, resulting in a lower thermal decomposition temperature.

[0104] Zeta potential (mV) analysis The Zeta potentials of Examples 1, 2, and 3 are -28 mV, -25 mV, and -22 mV respectively.

[0105] For Comparative Example 8, it is -15 mV; for Comparative Example 9, it is -20 mV; for Comparative Example 10, it is -18 mV; for Comparative Example 11, it is -12 mV; for Comparative Example 12, it is -21 mV; for Comparative Example 13, it is -19 mV; for Comparative Example 14, it is -25 mV.

[0106] Analysis: The Zeta potential in Examples 1, 2, and 3 is relatively low, indicating that the surface of kaolin has strong charges after modification, making the particles more likely to disperse. A lower Zeta potential (such as -28 mV in Example 1) can effectively improve the dispersibility of the material and reduce the tendency to agglomerate.

[0107] The Zeta potential of Comparative Examples 8, 9, 10, 11, 12, 13, and 14 is generally high, indicating poor dispersibility, which may lead to easy aggregation of kaolin particles and is not conducive to applications.

[0108] FTIR characteristic peak analysis The FTIR characteristic peaks of Examples 1, 2, and 3 are at 3400 cm -1 , 3450 cm -1 , and 3375 cm -1 respectively, showing the presence of hydration groups and hydrophilic groups to varying degrees.

[0109] The FTIR characteristic peaks of Comparative Examples 8 to 14 are generally around 3410 cm -1 , with slight differences, indicating that the hydration groups on the surface of kaolin cannot be fully modified in the absence of a modifier.

[0110] XPS analysis The XPS analysis peaks of Examples 1, 2, and 3 are 1022 eV, 1019 eV, and 1020 eV respectively.

[0111] For Comparative Example 8, it is 1018 eV, for Comparative Example 9, it is 1016 eV, for Comparative Example 10, it is 1021 eV, for Comparative Example 11, it is 1017 eV, for Comparative Example 12, it is 1019 eV, for Comparative Example 13, it is 1022 eV, and for Comparative Example 14, it is 1018 eV.

[0112] Analysis: The XPS peaks of Examples 1, 2, and 3 are relatively high, indicating that there are more siloxane groups on the surface of the modified kaolin, and these modified groups can increase the surface reactivity and binding force of kaolin.

[0113] The XPS peaks of Comparative Examples 8, 9, 10, 11, 12, 13, and 14 are slightly lower, showing that when there is a lack of effective modification, there are fewer surface groups on kaolin and the performance improvement is limited.

[0114] From the comparison of the above data, Examples 1, 2, and 3 have significant advantages over Comparative Examples 8 - 14 in many aspects: Particle size: Example 2 has the smallest particle size (1.9 μm), which helps to increase the surface area and reactivity.

[0115] Contact angle: Example 3 shows the strongest hydrophobicity (89°), which is suitable for applications such as waterproofing that require hydrophobicity.

[0116] Thermal stability: The thermal decomposition temperature of Example 3 is the highest (620 °C), which is suitable for high-temperature environments.

[0117] Zeta potential: The Zeta potential of Example 1 is the smallest (-28 mV), showing the best dispersibility.

[0118] FTIR and XPS: The modification effects of Examples 1, 2, and 3 are more prominent, showing more functional functional groups and better surface reactivity.

[0119] In summary, through the synergistic effect of cellulase and succinic acid monoester, Examples 1, 2, and 3 have significantly improved the properties of kaolin such as particle size, hydrophobicity, thermal stability, and dispersibility, and the modification effect is more superior than that of Comparative Examples 8-14.

[0120] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for modifying kaolin powder, characterized in that, It includes the following steps: Prepare a modifier, and the modifier includes the following components in parts by mass: 3-aminopropyltriethoxysilane: 5-15 parts, polyether polyol phosphate: 3-12 parts, cellulase: 1-5 parts, succinic acid monoester: 2-8 parts, ethanol: 10-25 parts, deionized water: 20-40 parts, polyvinylpyrrolidone: 1-5 parts, sodium citrate: 0.5-3 parts, diatomite: 2-6 parts, kaolin: 80-120 parts; Pretreat the kaolin, and the pretreatment includes crushing, sieving and drying, and after completion, kaolin powder is obtained; Perform primary mixing. First, crush, sieve and dry the diatomite to obtain diatomite powder, and then mix the diatomite powder with the kaolin powder; Perform medium mixing. Mix 3-aminopropyltriethoxysilane with ethanol, and the ethanol concentration is 90-95%; Perform post mixing. Mix polyether polyol phosphate with deionized water; Perform final mixing. Mix the products obtained from primary mixing, medium mixing and post mixing, and then add sodium citrate and polyvinylpyrrolidone and mix evenly; Ferment. Add cellulase and succinic acid monoester to the product obtained from final mixing, stir evenly and then let it stand for fermentation; Dry. Dry and crush the fermented kaolin to obtain modified kaolin powder.

2. The kaolin powder modification method according to claim 1, characterized in that, In the pretreatment, the particle diameter of the kaolin powder after crushing and sieving is 1-5 μm, and the drying is carried out at a temperature of 80-120 °C for 2-4 h.

3. The kaolin powder modification method according to claim 1, characterized in that In the primary mixing, the particle diameter of the diatomite after crushing and sieving is 1-5 μm, the drying is carried out at a temperature of 100-120 °C for 2-4 h, and the kaolin powder and the diatomite powder are mixed at a rotation speed of 500-1000 rpm for 10-30 min.

4. The kaolin powder modification method according to claim 1, characterized in that In the medium mixing, 3-aminopropyltriethoxysilane and ethanol are mixed at a rotation speed of 300-500 rpm for 15-20 min.

5. The kaolin powder modification method according to claim 1, characterized in that, In the post mixing, polyether polyol phosphate and deionized water are mixed at a rotation speed of 450-600 rpm for 18-30 min.

6. The kaolin powder modification method according to claim 1, characterized in that, In the final mixing, the products obtained from primary mixing, medium mixing and post mixing are mixed at a rotation speed of 600-900 rpm for 30-40 min. After adding sodium citrate and polyvinylpyrrolidone, they are mixed at a rotation speed of 700-900 rpm for 40-50 min.

7. The kaolin powder modification method according to claim 1, characterized in that, In the fermentation, after adding cellulase and succinic acid monoester, they are mixed at a rotation speed of 300-500 rpm for 40-70 min. Then, under the condition of a temperature of 25-35 °C, anaerobic fermentation is carried out for 48-120 h. After the fermentation is completed, it is dried at a temperature of 80-120 °C for 120-240 min to remove excess moisture, and after crushing, modified kaolin powder is obtained.

8. The kaolin powder treated by the method for modifying kaolin powder according to any one of claims 1-7 is applied in the fields of plastics, rubbers, ceramics and coatings.

Images