High polymer modified organic lipophilic hydrophobic bentonite and its preparation method

Abstract

The application provides a high polymer material modified organic lipophilic hydrophobic bentonite and a preparation method thereof, belongs to the technical field of coating materials, and is a product of sodium-based bentonite modified by intercalation modification of a high polymer modifier and hydrophobic propylene glycol methyl ether acetate. The high polymer modifier is prepared by the reaction of methacryloyloxyethyl trimethyl ammonium chloride, caprolactone acrylate, gamma-methacryloyloxypropyl trimethoxysilane, bis(dodecyl)-3,3'-thiobispropionic acid ester, ammonium mercaptoacetate and ammonium persulfate initiator. The bentonite preparation method comprises pre-synthesis of the high polymer modifier, preparation and purification of bentonite slurry, intercalation modification of the high polymer, post-treatment and hydrophobic modification of the modified product. The application solves the problems of strong hydrophilicity and poor dispersion of natural bentonite and weak interface combination and insufficient thixotropy of early organic bentonite from the molecular level, and realizes the performance upgrading of lipophilic hydrophobic, stable dispersion and long-acting protection.

Description

Technical Field

[0001] This invention pertains to the field of coating materials technology, specifically relating to a polymer-modified organic oleophilic and hydrophobic bentonite and its preparation method. Background Technology

[0002] In the field of high-performance industrial coatings, bentonite, as a key functional additive, is widely used in anti-corrosion coatings, high-temperature resistant coatings, and marine heavy-duty anti-corrosion coatings due to its unique layered silicate structure and excellent colloidal and suspension properties. It plays a crucial role in preventing sedimentation, thickening, thixotropy, and enhancing the mechanical properties of the coating. Industrial coatings are used in extremely demanding environments, requiring long-term resistance to acid and alkali corrosion, salt spray corrosion, high-temperature aging, and mechanical wear. This necessitates stable storage properties, uniform coatability, and long-lasting protection in the coating system, and the performance of bentonite directly determines the overall quality of the coating.

[0003] From a technological development perspective, bentonite used in industrial coatings has undergone an upgrade from natural sodium / calcium-based bentonite to organically modified bentonite. Natural bentonite, due to its rich hydroxyl content, exhibits strong hydrophilicity and poor dispersibility in solvent-based industrial coatings, easily agglomerating and forming precipitates, thus failing to provide a stable anti-settling and thickening effect. Early organically modified bentonite underwent intercalation treatment with quaternary ammonium salt cationic surfactants, which improved hydrophobicity and made it suitable for solvent-based systems. However, the degree of modification was limited, and the interlayer spacing could only be slightly increased. In high-performance coatings with high solids content and high viscosity, problems such as uneven dispersion and insufficient thixotropy still existed, leading to pigment sedimentation during coating storage and easy sagging or orange peel phenomena during application.

[0004] As industrial coatings develop towards higher protection, lower VOCs, and longer-lasting performance, the shortcomings of existing bentonite are becoming increasingly apparent. The following problems remain: the organic modification groups of traditional organic bentonite differ significantly in structure from the resin matrix (such as epoxy resin and polyimide resin) in high-performance coatings, resulting in weak interfacial bonding. This leads to the formation of micropores after coating curing, reducing the coating's impermeability and corrosion resistance, making it difficult to meet the long-lasting corrosion protection requirements of marine engineering, petrochemicals, and other fields. To address these issues, developing polymer-modified organic oleophilic and hydrophobic bentonite has become an inevitable trend. Summary of the Invention

[0005] To address the problems of high water absorption, poor oleophilicity, poor dispersibility, and poor interfacial compatibility in existing bentonite, this invention provides a polymer-modified organic oleophilic-hydrophobic bentonite and its preparation method. By replacing traditional small-molecule quaternary ammonium salts with polymer modifiers, this invention solves the problems of high hydrophilicity and poor dispersibility in natural bentonite, as well as the weak interfacial bonding and insufficient thixotropy in early organic bentonite at the molecular level, achieving performance upgrades in terms of oleophilic-hydrophobic properties, stable dispersion, and long-lasting protection. The specific technical solution is as follows:

[0006] A polymer-modified organic oleophilic and hydrophobic bentonite, wherein the bentonite is a sodium-based bentonite that has been intercalated with a polymer modifier and hydrophobized with propylene glycol methyl ether acetate; the polymer modifier is prepared by reacting methacryloyloxyethyltrimethylammonium chloride, caprolactone acrylate, γ-methacryloyloxypropyltrimethoxysilane, di(dodecyl)-3,3'-thiodipropionate, ammonium mercaptoacetate and ammonium persulfate initiator.

[0007] The polymer modifier is composed of methacryloyloxyethyltrimethylammonium chloride, caprolactone acrylate, γ-methacryloyloxypropyltrimethoxysilane, di(dodecyl)-3,3'-thiodipropionate and ammonium mercaptoacetate in a mass ratio of (8-12):(12-15):(5-8):(0.5-0.8):(0.1-0.3).

[0008] The sodium-based bentonite has a montmorillonite content of ≥85wt%.

[0009] The preparation method of the above-mentioned polymer-modified organic oleophilic and hydrophobic bentonite includes the following steps:

[0010] S1, Pre-synthesis of polymer modifier:

[0011] Isopropanol and deionized water were mixed and heated to 75℃~80℃ to obtain a solvent; methacryloyloxyethyltrimethylammonium chloride, caprolactone acrylate, γ-methacryloyloxypropyltrimethoxysilane, di(dodecyl)-3,3'-thiodipropionate and ammonium mercaptoacetate were mixed in a mass ratio of (8~12):(12~15):(5~8):(0.5~0.8):(0.1~0.3) to obtain a mixture; under nitrogen protection and continuous stirring, the mixture and ammonium persulfate initiator were added to the solvent, and the reaction was carried out at 75℃~80℃ for 6h~8h with continuous stirring; after cooling, a polymer modifier was obtained.

[0012] S2, Preparation and purification of bentonite slurry:

[0013] Sodium-based bentonite powder is added to hot deionized water and sheared to disperse it, forming a uniform slurry; centrifugation is performed, and the upper layer of bentonite colloid is collected.

[0014] S3, polymer intercalation modification:

[0015] Dilute the bentonite colloid with deionized water and adjust the pH to 4.5-5.0 to obtain a turbid liquid. Add a polymer modifier to the turbid liquid at 55℃-65℃ and 400rpm-500rpm, raise the temperature to 80℃-85℃, and continue stirring for 6h-8h. Filter by suction or pressure, and take the filter cake to obtain the modified product.

[0016] S4, Post-treatment and hydrophobicization of the modified product:

[0017] The modified material is washed with deionized water until no chloride ions are present. Finally, it is filtered by suction or pressure to obtain a purified filter cake. The purified filter cake is broken up and added to propylene glycol methyl ether acetate. It is sheared and dispersed, and solvent displacement is performed. The material is then filtered, dried, pulverized, and sieved to obtain polymer-modified organic oleophilic and hydrophobic bentonite.

[0018] In step S1 of the above preparation method, the volume ratio of isopropanol to deionized water is (1-1.5):1; the stirring speed is 250 rpm to 300 rpm; the amount of ammonium persulfate initiator added is 0.8% to 1.2% of the mass of the mixture; the amount of solvent used is 5 to 6 times the mass of the mixture; and the process involves cooling to room temperature.

[0019] In step S2 of the above preparation method, the amount of hot deionized water used is 5 to 6 times the mass of sodium-based bentonite powder; the temperature of the hot deionized water is 80℃ to 85℃; the shear dispersion is performed at 4000 rpm to 5000 rpm for 30 to 40 minutes; and the centrifugation is performed at 5000 rpm to 6000 rpm for 10 to 15 minutes.

[0020] In step S3 of the above preparation method, the bentonite colloid is diluted with deionized water to 4 to 5 times its volume; the pH value is adjusted with an aqueous solution of acetic acid with a concentration of 5 wt% to 8 wt%; and the amount of polymer modifier added is 15% to 20% of the volume of the turbid liquid.

[0021] In step S4 of the above preparation method, the amount of propylene glycol methyl ether acetate is 10 to 12 times the mass of the purified filter cake; the shear dispersion is performed at 4000 rpm to 5000 rpm for 20 to 30 minutes; the solid is extracted by vacuum filtration; the drying is performed by vacuum drying to constant weight; and the pulverization is performed by air jet pulverization.

[0022] In step S4 of the above preparation method, the particle size range of the polymer-modified organic oleophilic and hydrophobic bentonite is between 400 mesh and 2000 mesh.

[0023] The above-mentioned use of a polymer-modified organic oleophilic and hydrophobic bentonite in the preparation of coatings and suspending agents.

[0024] This invention provides a polymer-modified organic oleophilic and hydrophobic bentonite and its preparation method, the beneficial effects of which include:

[0025] I. This invention replaces traditional small-molecule quaternary ammonium salts with polymeric modifiers, addressing the problems of strong hydrophilicity and poor dispersion of natural bentonite, and weak interfacial bonding and insufficient thixotropy of early organic bentonite at the molecular level. This achieves performance upgrades in terms of oleophilicity and hydrophobicity, stable dispersion, and long-lasting protection. The polymeric modifier exhibits high stability and is compatible with various coatings. The in-situ crosslinking effect of the silane coupling agent eliminates micropores in the coating, meeting stringent corrosion protection requirements.

[0026] II. Synergistic effect of polymeric modifier monomers: The cationic sites of methacryloyloxyethyltrimethylammonium chloride provide Na+ between montmorillonite layers. + The ion exchange anchoring point of caprolactone acrylate enhances its compatibility with the resin through its flexible lipophilic chain; γ-methacryloyloxypropyltrimethoxysilane forms covalent bonds to strengthen interfacial bonding; di(dodecyl)-3,3'-thiodipropionate optimizes the polymer chain structure; and ammonium mercaptoacetate regulates the molecular weight to ensure intercalation efficiency. The five components work together to achieve synergistic effects of anchoring, compatibility, crosslinking, and chain control. The absence of any one of these components will result in a decrease in performance.

[0027] III. Matching Sodium-Based Bentonite with Modifiers: Sodium-based bentonite has a larger interlayer spacing, providing space for polymer chain intercalation, and Na... + It readily exchanges cations with modifiers, ensuring modification efficiency.

[0028] IV. Parameters for pre-synthesis of polymers: reaction temperature of 75℃-80℃, nitrogen protection to ensure stable polymerization reaction, isopropanol and deionized water solvent system to balance monomer solubility and polymerization rate, and precise control of ammonium persulfate dosage to improve initiation efficiency and avoid under- or over-polymerization.

[0029] V. Parameters for slurry purification: Shear dispersion in hot deionized water at 80℃-85℃ promotes the depolymerization of bentonite, and centrifugation removes sand and gravel impurities to ensure that the subsequent intercalation target is high-purity montmorillonite colloid.

[0030] VI. Intercalation modification parameters: pH 4.5-5.0 ensures silane hydrolysis-condensation equilibrium, preventing both rapid self-polymerization and insufficient hydrolysis; initial temperature of 55℃-65℃ and stepwise temperature increase of 80℃-85℃ to ensure uniform dispersion of the modifier before increasing the reaction rate; stirring to prevent colloidal agglomeration.

[0031] 7. Use propylene glycol methyl ether acetate solvent to completely remove residual moisture and hydrophilic impurities, shear dispersion to ensure uniform coating of hydrophobic solvent, and vacuum drying to avoid high temperature damage to the modified structure.

[0032] In summary, this invention designs an anchoring and compatible polymeric modifier. Through precise intercalation and solvent displacement processes, bentonite is modified, exhibiting comprehensive properties such as oleophilicity and hydrophobicity, stable dispersion, interfacial compatibility, and good rheological properties, forming a closed-loop synergy. Ion exchange ensures the initial anchoring of the modifier, silane hydrolysis and condensation of covalent bonds strengthen the binding between the modifier and bentonite, and propylene glycol methyl ether acetate solvent displacement eliminates hydrophilic residues. The synergistic effect of these three processes ensures that the bentonite is both firmly anchored and thoroughly oleophilic and hydrophobic, avoiding the problems of easy desorption of the modifier caused by single ion exchange and weak binding caused by single hydrophobic treatment, thus achieving synergistic effects. Detailed Implementation

[0033] The present invention will be further described below with reference to specific implementation examples, but the present invention is not limited to these embodiments.

[0034] Example 1

[0035] A polymer-modified organic oleophilic and hydrophobic bentonite, wherein the bentonite is a sodium-based bentonite that has been intercalated with a polymer modifier and hydrophobized by propylene glycol methyl ether acetate; the particle size of the sodium-based bentonite is between 270 mesh and 800 mesh.

[0036] The preparation method of the above-mentioned polymer-modified organic oleophilic and hydrophobic bentonite includes the following steps:

[0037] S1, Pre-synthesis of polymer modifier:

[0038] Isopropanol and deionized water were mixed in a volume ratio of 1.2:1 and heated to 78°C to obtain a solvent. Methacryloxyethyltrimethylammonium chloride, caprolactone acrylate, γ-methacryloxypropyltrimethoxysilane, di(dodecyl)-3,3'-thiodipropionate, and ammonium mercaptoacetate were mixed in a mass ratio of 10:13.5:6.5:0.7:0.2 to obtain a mixture. Under nitrogen protection and stirring at 280 rpm, the mixture and 1.0% (by mass) of ammonium persulfate initiator were added to a solvent at a mass of 5.5 times the mass of the mixture. The mixture was stirred continuously at 78°C for 7 hours. After cooling to room temperature, a polymer modifier was obtained.

[0039] Dissolve the ammonium persulfate initiator in a small amount of deionized water before adding it.

[0040] S2, Preparation and purification of bentonite slurry:

[0041] Sodium-based bentonite powder with a montmorillonite content of 89 wt% was added to 5.5 times its weight of hot deionized water at 82℃ and sheared and dispersed at 4500 rpm for 35 min to form a uniform slurry; centrifuged at 5500 rpm for 12 min, the bottom sand and gravel impurities were discarded, and the upper stable bentonite colloid was collected.

[0042] S3, polymer intercalation modification:

[0043] Bentonite colloid was diluted with deionized water to 4.5 times its volume, and the pH was adjusted to 4.7 with a 6.5 wt% acetic acid aqueous solution to obtain a turbid liquid. A polymer modifier, at 18% of the liquid volume, was added to the turbid liquid under stirring at 60℃ and 450 rpm. The temperature was raised to 82℃, and stirring was continued at 450 rpm for 7 hours (during which two key reactions occur simultaneously: ion exchange occurs between the cations on the polymer chains and the Na+ between the montmorillonite layers; the silane coupling agent is partially hydrolyzed and condenses with the silanol groups on the surface of the bentonite sheets to form strong covalent grafts). The mixture was then filtered, and the filter cake was collected to obtain the modified product.

[0044] S4, Post-treatment and hydrophobicization of the modified product:

[0045] The modified material was washed with deionized water until no chloride ions were present (no white precipitate was detected by AgNO3). Finally, it was filtered to obtain a purified filter cake. The purified filter cake was broken up and added to 11 times its mass of propylene glycol methyl ether acetate. It was sheared and dispersed at 4500 rpm for 25 min to perform solvent replacement (this process is a key step to thoroughly remove moisture and residual hydrophilic substances using organic solvents to achieve deep oleophilic-hydrophobic conversion). The solid was recovered by filtration, vacuum dried at 65℃ to constant weight, air-jet pulverized, and sieved (particle size range between 400 mesh and 2000 mesh) to obtain polymer-modified organic oleophilic-hydrophobic bentonite.

[0046] Example 2

[0047] A polymer-modified organic oleophilic and hydrophobic bentonite, wherein the bentonite is a sodium-based bentonite that has been intercalated with a polymer modifier and hydrophobized by propylene glycol methyl ether acetate; the particle size of the sodium-based bentonite is between 270 mesh and 800 mesh.

[0048] The preparation method of the above-mentioned polymer-modified organic oleophilic and hydrophobic bentonite includes the following steps:

[0049] S1, Pre-synthesis of polymer modifier:

[0050] Isopropanol and deionized water were mixed in a volume ratio of 1:1 and heated to 80°C to obtain a solvent. Methacryloxyethyltrimethylammonium chloride, caprolactone acrylate, γ-methacryloxypropyltrimethoxysilane, di(dodecyl)-3,3'-thiodipropionate, and ammonium mercaptoacetate were mixed in a mass ratio of 8:15:5:0.8:0.1 to obtain a mixture. Under nitrogen protection and stirring at 300 rpm, the mixture and 0.8% (by mass) of ammonium persulfate initiator were added to a solvent at a mass of 6 times the mass of the mixture. The mixture was stirred continuously at 75°C for 8 hours. After cooling to room temperature, a polymer modifier was obtained.

[0051] Dissolve the ammonium persulfate initiator in a small amount of deionized water before adding it.

[0052] S2, Preparation and purification of bentonite slurry:

[0053] Sodium-based bentonite powder with a montmorillonite content of 85 wt% was added to 5 times its weight of hot deionized water at 85℃ and sheared and dispersed at 4000 rpm for 40 min to form a uniform slurry; centrifuged at 5000 rpm for 15 min, the bottom sand and gravel impurities were discarded, and the upper stable bentonite colloid was collected.

[0054] S3, polymer intercalation modification:

[0055] Bentonite colloid was diluted with deionized water to four times its volume, and the pH was adjusted to 4.5 with an 8wt% acetic acid aqueous solution to obtain a turbid liquid. A polymer modifier, at 20% of the liquid volume, was added to the turbid liquid under stirring at 65℃ and 400rpm. The temperature was raised to 80℃, and stirring was continued at 400rpm for 6 hours (during which two key reactions occur simultaneously: ion exchange occurs between the cations on the polymer chains and the Na+ between the montmorillonite layers; the silane coupling agent is partially hydrolyzed and condenses with the silanol groups on the surface of the bentonite sheets to form strong covalent grafts). The mixture was then filtered, and the filter cake was collected to obtain the modified product.

[0056] S4, Post-treatment and hydrophobicization of the modified product:

[0057] The modified material was washed with deionized water until no chloride ions were present (no white precipitate was detected by AgNO3), and finally filtered to obtain a purified filter cake. The purified filter cake was broken up and added to 12 times its mass of propylene glycol methyl ether acetate. It was sheared and dispersed at 4000 rpm for 30 min to perform solvent replacement (this process is a key step to thoroughly remove moisture and residual hydrophilic substances using organic solvents to achieve deep oleophilic-hydrophobic conversion). The solid was recovered by vacuum filtration, dried under vacuum at 60℃ to constant weight, air-jet pulverized, and sieved (particle size range between 400 mesh and 2000 mesh) to obtain polymer-modified organic oleophilic-hydrophobic bentonite.

[0058] Example 3

[0059] A polymer-modified organic oleophilic and hydrophobic bentonite, wherein the bentonite is a sodium-based bentonite that has been intercalated with a polymer modifier and hydrophobized by propylene glycol methyl ether acetate; the particle size of the sodium-based bentonite is between 270 mesh and 800 mesh.

[0060] The preparation method of the above-mentioned polymer-modified organic oleophilic and hydrophobic bentonite includes the following steps:

[0061] S1, Pre-synthesis of polymer modifier:

[0062] Isopropanol and deionized water were mixed in a volume ratio of 1.5:1 and heated to 75°C to obtain a solvent. Methacryloxyethyltrimethylammonium chloride, caprolactone acrylate, γ-methacryloxypropyltrimethoxysilane, di(dodecyl)-3,3'-thiodipropionate, and ammonium mercaptoacetate were mixed in a mass ratio of 12:12:8:0.5:0.3 to obtain a mixture. Under nitrogen protection and stirring at 250 rpm, the mixture and 1.2% (by mass) of ammonium persulfate initiator were added to a solvent five times the mass of the mixture. The mixture was stirred continuously at 80°C for 6 hours. After cooling to room temperature, a polymer modifier was obtained.

[0063] Dissolve the ammonium persulfate initiator in a small amount of deionized water before adding it.

[0064] S2, Preparation and purification of bentonite slurry:

[0065] Sodium-based bentonite powder with a montmorillonite content of 87wt% was added to 6 times its weight of hot deionized water at 80℃ and sheared and dispersed at 5000rpm for 30min to form a uniform slurry; centrifuged at 6000rpm for 10min, the bottom sand and gravel impurities were discarded, and the upper stable bentonite colloid was collected.

[0066] S3, polymer intercalation modification:

[0067] Bentonite colloid was diluted with deionized water to 5 times its volume, and the pH was adjusted to 5.0 with 5wt% acetic acid aqueous solution to obtain a turbid liquid. A polymer modifier (15% of the liquid volume) was added to the turbid liquid under stirring at 55℃ and 500rpm. The temperature was raised to 85℃, and stirring was continued at 500rpm for 8 hours (during which two key reactions occur simultaneously: ion exchange occurs between the cations on the polymer chains and the Na+ between the montmorillonite layers; the silane coupling agent is partially hydrolyzed and condenses with the silanol groups on the surface of the bentonite sheets to form strong covalent grafts). The mixture was then filtered, and the filter cake was collected to obtain the modified product.

[0068] S4, Post-treatment and hydrophobicization of the modified product:

[0069] The modified material was washed with deionized water until no chloride ions were present (no white precipitate was detected by AgNO3). Finally, it was filtered to obtain a purified filter cake. The purified filter cake was broken up and added to 10 times its mass of propylene glycol methyl ether acetate. It was sheared and dispersed at 5000 rpm for 20 min to perform solvent replacement (this process is a key step to thoroughly remove moisture and residual hydrophilic substances using organic solvents to achieve deep oleophilic-hydrophobic conversion). The solid was recovered by filtration, vacuum dried at 70℃ to constant weight, air-jet pulverized, and sieved (particle size range between 400 mesh and 2000 mesh) to obtain polymer-modified organic oleophilic-hydrophobic bentonite.

[0070] The raw materials used in the above embodiments are sourced as follows: Isopropanol from Shandong Zhengxing New Materials Co., Ltd.; Methacryloxyethyltrimethylammonium chloride from Hubei Wande Chemical Co., Ltd.; Caprolactone acrylate from Hubei Xinhongli Chemical Co., Ltd.; γ-Methacryloxypropyltrimethoxysilane from Tianmen Hengchang Chemical Co., Ltd.; Di(dodecyl)-3,3'-thiodipropionate from Hubei Xinrunde Chemical Co., Ltd.; Ammonium mercaptoacetate from Hubei Yongkuo Technology Co., Ltd.; Ammonium persulfate initiator from Nanjing Sifanke Chemical Co., Ltd.; Sodium bentonite with a montmorillonite content ≥85% and a particle size range of 270 mesh to 800 mesh; and Propylene glycol methyl ether acetate from Shandong Jinyueyuan New Materials Co., Ltd.

[0071] Comparative Example 1

[0072] The difference between the preparation method of bentonite and Example 1 is that in S1, ammonium mercaptoacetate is not added.

[0073] Comparative Example 2

[0074] The difference between the preparation method of bentonite and Example 1 is that in S1, the mass ratio of methacryloyloxyethyltrimethylammonium chloride, caprolactone acrylate, γ-methacryloyloxypropyltrimethoxysilane, di(dodecyl)-3,3'-thiodipropionate and mercaptoacetate is changed to 18:5.5:6.5:0.7:0.2.

[0075] Comparative Example 3

[0076] The difference between the preparation method of bentonite and Example 1 is that in S1, the mass ratio of methacryloyloxyethyltrimethylammonium chloride, caprolactone acrylate, γ-methacryloyloxypropyltrimethoxysilane, di(dodecyl)-3,3'-thiodipropionate and mercaptoacetate is changed to 3.5:20::6.5:0.7:0.2.

[0077] Comparative Example 4

[0078] The difference between the preparation method of bentonite and Example 1 is that in S1, the mass ratio of methacryloyloxyethyltrimethylammonium chloride, caprolactone acrylate, γ-methacryloyloxypropyltrimethoxysilane, di(dodecyl)-3,3'-thiodipropionate and mercaptoacetate is changed to 10:18:2:0.7:0.2.

[0079] Comparative Example 5

[0080] The difference between the preparation method of bentonite and Example 1 is that in S3, the pH value is adjusted to 4.0 with a 6.5wt% acetic acid aqueous solution to obtain a turbid liquid.

[0081] Comparative Example 6

[0082] The difference between the preparation method of bentonite and Example 1 is that in S3, the pH value is adjusted to 5.5 with a 6.5wt% acetic acid aqueous solution to obtain a turbid liquid.

[0083] Comparative Example 7

[0084] The difference between the preparation method of bentonite and Example 1 is that in S3, the amount of polymer modifier added is 5% of the volume of the turbid liquid.

[0085] Comparative Example 8

[0086] The difference between the preparation method of bentonite and that in Example 1 is that in S3, a polymer modifier is added and then the reaction is carried out at room temperature with stirring.

[0087] The bentonite samples were dried in a vacuum drying oven at 65°C for 2 hours, then removed and cooled to room temperature in a desiccator to obtain pretreated samples.

[0088] I. Hydrophobicity Test:

[0089] A powder tablet press was used to compress 1.0 g of pretreated sample into uniform discs with a diameter of 10 mm and a thickness of 2 mm under a pressure of 10 MPa. Using a contact angle meter, 5 μL of ultrapure water was dropped at different positions on the disc surface, and the static contact angle was recorded for 2 seconds. Five points were measured for each sample, and the average value was taken.

[0090] II. Oil Absorption Test:

[0091] Weigh 1.00g of the pretreated sample onto a glass plate, and add linseed oil dropwise at a uniform rate using a burette while continuously grinding and stirring with a spatula until the sample is completely wetted and agglomerated into a paste with no loose particles and a uniform feel. Record the volume of linseed oil consumed and calculate the oil absorption value; oil absorption value = mass of linseed oil consumed (g) / mass of sample (g), and convert the density of linseed oil to 0.93g / mL; the relative standard deviation of the determination of 5 parallel samples is ≤3%.

[0092] III. Dispersion stability test:

[0093] Weigh the raw materials according to the mass ratio of epoxy resin (E-51): curing agent (polyamide 650): pretreated sample: titanium dioxide (D50 is 0.3μm) = 100:30:5:20, add xylene, and use a high-speed disperser to stir at 1500 rpm for 30 min to ensure uniform dispersion. Adjust the viscosity of the system to 500 mPa·s (25℃) to obtain the coating system.

[0094] Centrifugal sedimentation rate test: Take 10.0 mL of the coating system, place it in a centrifuge tube, centrifuge at 5000 rpm for 30 min, and weigh the mass of the precipitate (g) and the total mass of the coating system (g); 3 parallel samples per group; centrifugal sedimentation rate = (mass of precipitate / total mass of coating system) × 100%.

[0095] Settling rate test: Pour 200 mL of the coating system into a graduated glass container, seal it, and record the initial liquid level (mm). Store it in a constant temperature oven at 50℃ for 30 days and record the settling layer height (mm); Settling rate = (settling layer height / initial liquid level) × 100%.

[0096] IV. Interface compatibility testing:

[0097] Weigh the raw materials according to the mass ratio of epoxy resin (E-51):curing agent (polyamide 650):pretreated sample = 100:30:5, add xylene, and stir at 1500 rpm for 30 min using a high-speed disperser to ensure uniform dispersion. Adjust the system viscosity to 500 mPa·s (25℃) to obtain the coating system. Apply the coating system to a Q235 steel plate and cure at 80℃ for 2 h, with a final dry film thickness of 85±2 μm. Place the cured paint plate at 25℃ and 50%RH for 24 h, and perform a bending test using a Φ1mm shaft at a bending angle of 180°. Test three parallel samples per group and observe the paint film condition.

[0098] V. Thixotropic index test:

[0099] A propylene glycol methyl ether acetate dispersion containing 5.0 wt% pretreated sample was prepared. The dispersion was stirred at 1500 rpm for 30 min using a high-speed disperser to ensure uniform dispersion. 100 g of the dispersion was incubated in a 25°C water bath for 30 min, and then tested using a rotational rheometer at 25°C: the shear rate decreased from 0.1 s⁻¹. -1 linearly increase to 100s -1 (Upward line), record for 0.5 seconds -1 and 100s -1 The viscosity values ​​η1 and η2 are calculated. Thixotropic index (TI) = η1 / η2; the average of 3 parallel samples is taken.

[0100] Table 1. Test Results (Average Values)

[0101]

[0102] Examples 1 to 3 achieved a comprehensive improvement in the performance of bentonite by optimizing the monomer ratio and preparation process of the polymer modifier. In the polymer modifier synthesis stage, the proportions of methacryloyloxyethyltrimethylammonium chloride, caprolactone acrylate, and γ-methacryloyloxypropyltrimethoxysilane were balanced, and ammonium mercaptoacetate (chain transfer agent) was used to precisely control the molecular weight distribution, ensuring that the polymer chains possessed sufficient cationic sites and interlayer Na+ in montmorillonite. + It can undergo ion exchange and improve lipophilicity through flexible segments. At the same time, the silane coupling agent can hydrolyze to generate silanol groups, which can then form covalent bonds with the silanol groups of bentonite sheets.

[0103] During the intercalation modification stage, the optimization of pH and temperature ensured the full progress of ion exchange and silane condensation reactions, effectively expanding the interlayer spacing of bentonite and allowing the modifier to be uniformly loaded on the surface and between layers. Subsequent solvent replacement with propylene glycol methyl ether acetate thoroughly removed residual moisture and hydrophilic substances, achieving deep hydrophobicity. Ultimately, the bentonite and the coating resin matrix formed molecular-level compatibility, with no micropores at the interface, and exhibited excellent dispersion stability, thixotropy, and mechanical properties.

[0104] The effect of missing chain transfer agent in Comparative Example 1: Ammonium mercaptoacetate, as a chain transfer agent, plays a crucial role in inhibiting excessive polymer chain growth and narrowing the molecular weight distribution. Without its addition, the polymer chains in the polymerization reaction are prone to random growth, resulting in excessively large molecular weights and uneven distribution. On the one hand, excessively long molecular chains struggle to penetrate the interlayer channels of montmorillonite, significantly reducing intercalation efficiency and interlayer spacing. This reduces the loading of hydrophilic and oleophilic groups on the surface and between layers, directly leading to decreased hydrophobicity and oleophilicity. On the other hand, the binding force between the modifier with uneven molecular weight and the bentonite sheets differs, preventing the formation of a uniform and stable dispersion network in the coating system. This increases the tendency for particle agglomeration, manifested as increased centrifugal and static settling rates. Simultaneously, the interfacial interaction between the abnormally molecular weight polymer chains and the resin matrix weakens, reducing the mechanical toughness of the coating and causing slight cracking during bending tests.

[0105] The chain reaction of monomer imbalance in Comparative Examples 2 and 3: In Comparative Example 2, the excess of methacryloyloxyethyltrimethylammonium chloride led to an excessively high cation density in the montmorillonite interlayers, abnormally enhancing the electrostatic repulsion between the layers, which in turn damaged the dispersion stability and caused particle agglomeration and sedimentation. Insufficient caprolactone acrylate reduced the coverage of lipophilic groups on the bentonite surface, decreased the oil absorption value, and worsened the structural compatibility between the flexible segments and the resin matrix, weakening the interfacial bonding force, increasing the brittleness of the coating, and causing significant cracking in the bending test. Furthermore, insufficient hydrophobic groups directly led to a decrease in the water contact angle, weakened the hydrophobic interaction between particles in the dispersion system, and decreased the thixotropic index. In Comparative Example 3, the insufficient amount of methacryloyloxyethyltrimethylammonium chloride reduced the number of ion exchange sites, resulting in insufficient driving force for intercalation modification. The polymer modifier was difficult to effectively anchor in the montmorillonite interlayers and surface, leading to a significant decrease in the modifier loading. The interlayer spacing failed to expand effectively, and the number of oleophilic and hydrophobic groups was insufficient, resulting in a significant decrease in the water contact angle and oil absorption value. The modifier and bentonite were not firmly bonded, and desorption easily occurred in the coating system, failing to play a stable dispersion role, exacerbating particle agglomeration, and significantly increasing the sedimentation rate. Excessive caprolactone acrylate, due to ineffective loading, allowed free flexible chains to easily entangle with each other, further aggravating particle agglomeration. At the same time, excessive flexible chains reduced the mechanical strength of the coating, leading to cracking and peeling in bending tests. The dispersion system lacked sufficient modifiers to construct a stable rheological network, and the thixotropic index dropped to a low level.

[0106] Interfacial defects due to insufficient silane coupling agent in Comparative Example 4: γ-methacryloxypropyltrimethoxysilane, as a silane coupling agent, generates silanol groups through hydrolysis, which condense with silanol groups on the surface of bentonite sheets to form covalent grafts. Simultaneously, its organic segments enhance interfacial compatibility with the resin matrix. When this component is insufficient, the covalent grafting efficiency decreases, and the binding of the polymer modifier to bentonite becomes primarily ion exchange, significantly weakening the bond strength. During dispersion, the modifier easily detaches from the sheets, leading to a decline in oleophilic and hydrophobic properties. More critically, the "bridging" effect provided by the silane coupling agent is insufficient, weakening the interfacial bonding between bentonite and the resin matrix. Micropores easily form at the coating interface, reducing mechanical toughness and causing slight cracking during bending tests. Furthermore, insufficient covalent grafting makes it difficult for the bentonite sheets to form a stable spatial network structure in the system, resulting in poor dispersion stability, increased sedimentation rate, and decreased thixotropic index.

[0107] The effect of pH deviation on reaction efficiency in Comparative Examples 5 and 6: The acidity of Comparative Example 5 was too strong. The pH value during the intercalation modification stage directly controlled the hydrolysis-condensation equilibrium of the silane coupling agent and the dissociation efficiency of the cationic monomer. At pH=4.0, the strongly acidic environment accelerated the hydrolysis of the silane coupling agent. The generated silanol groups easily underwent a rapid self-condensation reaction to form oligomers, rather than combining with the silanol groups on the surface of the bentonite sheets. This resulted in a significant decrease in covalent bond grafting efficiency and insufficient loading of the modifier. At the same time, the strong acidity inhibited the cationic dissociation of methacryloyloxyethyltrimethylammonium chloride, reducing the rate and extent of the ion exchange reaction, and limiting the expansion of interlayer spacing. The combined effect of these two factors resulted in oleophilic and hydrophobic properties and dispersion stability that were better than some comparative examples, but still inferior to the examples. The interfacial adhesion of the coating decreased slightly, and the bending test showed no cracking but slight wrinkling. The rheological properties decreased due to insufficient interparticle interaction, and the thixotropic index decreased. Comparative Example 6 is weakly acidic. At pH 5.5, the weakly acidic environment significantly slows down the hydrolysis rate of the silane coupling agent, resulting in insufficient silanol groups. This hinders the condensation reaction with the silanol groups on the bentonite sheet surface, leading to low covalent grafting efficiency. Simultaneously, the cation dissociation of methacryloyloxyethyltrimethylammonium chloride is insufficient in the weakly acidic environment, resulting in incomplete ion exchange and limited interlayer spacing expansion. Similar to Comparative Example 5, its oleophilic and hydrophobic properties, dispersion stability, and rheological properties fall between those of the examples and inferior comparative examples. The interfacial adhesion of the coating is slightly lower than that of the examples, and slight wrinkling occurs during bending tests.

[0108] In Comparative Example 7, the modifier dosage was insufficient: the amount of polymeric modifier added (5% of the turbid liquid volume) was far below the requirement, failing to completely cover the active sites on the surface and between layers of the bentonite sheets; ion exchange and covalent grafting reactions were incomplete, resulting in limited interlayer spacing expansion and insufficient loading of oleophilic and hydrophobic groups, leading to a low water contact angle and low oil absorption value; the uncovered hydroxyl groups have strong hydrophilicity and easily combine with water or polar substances in the system through hydrogen bonds, causing particle aggregation and increased sedimentation rate. Simultaneously, insufficient modifier prevented the construction of an effective spatial network structure in the coating system, resulting in a decrease in the thixotropic index, weakened adhesion at the coating interface due to insufficient modifier loading, and slight cracking during bending tests.

[0109] Kinetic obstacle due to insufficient reaction temperature in Comparative Example 8: Heating during the intercalation modification stage (80℃-85℃) is a key kinetic condition to ensure the full progress of ion exchange and silane condensation reactions. During stirring at room temperature, the molecular thermal motion rate decreases significantly: on the one hand, the cations of methacryloyloxyethyltrimethylammonium chloride react with the Na+ in the montmorillonite interlayer. +The exchange rate slows down, and the ion exchange reaction is incomplete. On the other hand, the activation energy of the hydrolysis and condensation reaction of the silane coupling agent is insufficient, making it difficult to start the reaction. Only a small amount of silanol groups are generated, and they cannot effectively bind with the bentonite layers. Ultimately, the modifier is only loaded in small amounts on the surface and between the layers of bentonite, with almost no increase in interlayer spacing, resulting in extremely poor oleophilic and hydrophobic properties. The binding force between the modifier and bentonite is extremely weak, making it easy to detach in the coating system. The particles completely agglomerate, and the sedimentation rate increases significantly. The coating interface has extremely poor bonding force due to the lack of effective modification, and cracking and peeling occur in the bending test. There is no stable network structure in the dispersion system, and the rheological properties reach the lowest level.

Claims

1. A polymer-modified organic oleophilic and hydrophobic bentonite, characterized in that, The bentonite is a sodium-based bentonite product obtained by intercalation modification with a polymer modifier and hydrophobication with propylene glycol methyl ether acetate; the polymer modifier is prepared by reacting methacryloyloxyethyltrimethylammonium chloride, caprolactone acrylate, γ-methacryloyloxypropyltrimethoxysilane, di(dodecyl)-3,3'-thiodipropionate, ammonium mercaptoacetate and ammonium persulfate initiator. The method for preparing the bentonite includes the following steps: S1, Pre-synthesis of polymer modifier: Isopropanol and deionized water were mixed and heated to 75℃~80℃ to obtain a solvent; methacryloyloxyethyltrimethylammonium chloride, caprolactone acrylate, γ-methacryloyloxypropyltrimethoxysilane, di(dodecyl)-3,3'-thiodipropionate and ammonium mercaptoacetate were mixed in a mass ratio of (8~12):(12~15):(5~8):(0.5~0.8):(0.1~0.3) to obtain a mixture; under nitrogen protection and continuous stirring, the mixture and ammonium persulfate initiator were added to the solvent, and the reaction was carried out at 75℃~80℃ for 6h~8h with continuous stirring; after cooling, a polymer modifier was obtained. S2, Preparation and purification of bentonite slurry: Sodium-based bentonite powder is added to hot deionized water and sheared to disperse it, forming a uniform slurry; centrifugation is performed, and the upper layer of bentonite colloid is collected. S3, polymer intercalation modification: Dilute the bentonite colloid with deionized water and adjust the pH to 4.5–5.0 to obtain a turbid liquid. Add 15%–20% of the volume of the turbid liquid as a polymer modifier to the turbid liquid while stirring at 55℃–65℃ and 400rpm–500rpm. Heat the mixture to 80℃–85℃ and continue stirring for 6h–8h. Filter the mixture by suction or pressure and collect the filter cake to obtain the modified product. S4, Post-treatment and hydrophobicization of the modified product: The modified material is washed with deionized water until no chloride ions are present. Finally, it is filtered by suction or pressure to obtain a purified filter cake. The purified filter cake is broken up and added to propylene glycol methyl ether acetate. It is sheared and dispersed, and solvent displacement is performed. The material is then filtered, dried, pulverized, and sieved to obtain polymer-modified organic oleophilic and hydrophobic bentonite.

2. The polymer-modified organic oleophilic and hydrophobic bentonite according to claim 1, characterized in that, The sodium-based bentonite has a montmorillonite content of ≥85wt%.

3. The preparation method of polymer-modified organic oleophilic and hydrophobic bentonite according to claim 1, characterized in that, Includes the following steps: S1, Pre-synthesis of polymer modifier: Isopropanol and deionized water were mixed and heated to 75℃~80℃ to obtain a solvent; methacryloyloxyethyltrimethylammonium chloride, caprolactone acrylate, γ-methacryloyloxypropyltrimethoxysilane, di(dodecyl)-3,3'-thiodipropionate and ammonium mercaptoacetate were mixed in a mass ratio of (8~12):(12~15):(5~8):(0.5~0.8):(0.1~0.3) to obtain a mixture; under nitrogen protection and continuous stirring, the mixture and ammonium persulfate initiator were added to the solvent, and the reaction was carried out at 75℃~80℃ for 6h~8h with continuous stirring; after cooling, a polymer modifier was obtained. S2, Preparation and purification of bentonite slurry: Sodium-based bentonite powder is added to hot deionized water and sheared to disperse it, forming a uniform slurry; centrifugation is performed, and the upper layer of bentonite colloid is collected. S3, polymer intercalation modification: Dilute the bentonite colloid with deionized water and adjust the pH to 4.5–5.0 to obtain a turbid liquid. Add 15%–20% of the volume of the turbid liquid as a polymer modifier to the turbid liquid while stirring at 55℃–65℃ and 400rpm–500rpm. Heat the mixture to 80℃–85℃ and continue stirring for 6h–8h. Filter the mixture by suction or pressure and collect the filter cake to obtain the modified product. S4, Post-treatment and hydrophobicization of the modified product: The modified material is washed with deionized water until no chloride ions are present. Finally, it is filtered by suction or pressure to obtain a purified filter cake. The purified filter cake is broken up and added to propylene glycol methyl ether acetate. It is sheared and dispersed, and solvent displacement is performed. The material is then filtered, dried, pulverized, and sieved to obtain polymer-modified organic oleophilic and hydrophobic bentonite.

4. The method for preparing polymer-modified organic oleophilic and hydrophobic bentonite according to claim 3, characterized in that, In S1, the volume ratio of isopropanol to deionized water is (1-1.5):1; the stirring speed is 250 rpm to 300 rpm; the amount of ammonium persulfate initiator added is 0.8% to 1.2% of the mass of the mixture; the amount of solvent used is 5 to 6 times the mass of the mixture; and the mixture is cooled to room temperature.

5. The method for preparing polymer-modified organic oleophilic and hydrophobic bentonite according to claim 3, characterized in that, In S2, the amount of hot deionized water used is 5 to 6 times the mass of sodium-based bentonite powder; the temperature of the hot deionized water is 80℃ to 85℃; the shear dispersion is performed at 4000 rpm to 5000 rpm for 30 to 40 minutes; and the centrifugation is performed at 5000 rpm to 6000 rpm for 10 to 15 minutes.

6. The method for preparing polymer-modified organic oleophilic and hydrophobic bentonite according to claim 3, characterized in that, In step S3, the bentonite colloid is diluted with deionized water to 4 to 5 times its volume; the pH value is adjusted using an aqueous solution of acetic acid with a concentration of 5 wt% to 8 wt%.

7. The method for preparing polymer-modified organic oleophilic and hydrophobic bentonite according to claim 3, characterized in that, In step S4, the amount of propylene glycol methyl ether acetate is 10 to 12 times the mass of the purified filter cake; the shear dispersion is performed at 4000 rpm to 5000 rpm for 20 to 30 minutes; the solid is extracted by vacuum filtration; the drying is performed by vacuum drying to constant weight; and the pulverization is performed by air jet pulverization.

8. The method for preparing polymer-modified organic oleophilic and hydrophobic bentonite according to claim 3, characterized in that, In S4, the particle size range of the polymer-modified organic oleophilic and hydrophobic bentonite is between 400 mesh and 2000 mesh.

9. The use of the polymer-modified organic oleophilic and hydrophobic bentonite according to claim 1 in the preparation of coatings and suspending agents.

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