Modified montmorillonite, method for preparing and using same, and polyamide composite

Abstract

This application provides modified montmorillonite, its preparation method and application, and polyamide composite materials, belonging to the technical field of modified montmorillonite. This application prepares a modified montmorillonite intermediate by using γ-aminopropyltriethoxysilane and montmorillonite in a first reaction, which enables pre-intercalation of γ-aminopropyltriethoxysilane, expanding the interlayer spacing of montmorillonite and reducing interlayer forces. Further, cerium salt is mixed with the first modified montmorillonite intermediate in the presence of a first solvent to carry out a second reaction. The amino group in γ-aminopropyltriethoxysilane can anchor cerium ions, providing sites for the in-situ generation of cerium phosphite. Then, phosphorous acid is mixed with a second modified montmorillonite intermediate in the presence of a second solvent to carry out a third reaction, generating cerium phosphite in-situ between the layers of the modified montmorillonite intermediate, achieving co-intercalation of γ-aminopropyltriethoxysilane and cerium phosphite, which can significantly improve the dispersibility and flame retardant properties of montmorillonite.

Description

Technical Field

[0001] This application relates to the field of modified montmorillonite technology, and in particular to modified montmorillonite, its preparation methods and applications, and polyamide composite materials. Background Technology

[0002] Montmorillonite, a layered silicate inorganic filler, is commonly used as a flame retardant carrier due to its wide availability, low cost, and halogen-free and environmentally friendly nature. However, montmorillonite is prone to agglomeration, and its flame-retardant effect is limited primarily through layered barrier properties. Modifying montmorillonite with coupling agents can improve its dispersibility and reduce agglomeration; modifying it with inorganic flame retardants can improve its flame retardancy. Nevertheless, traditionally modified montmorillonite still suffers from low flame-retardant efficiency and poor dispersibility.

[0003] Therefore, how to modify montmorillonite to improve its flame retardancy and dispersibility has become an urgent technical problem to be solved. Summary of the Invention

[0004] Based on this, the main objective of this application is to provide modified montmorillonite, its preparation method and application, and polyamide composite materials, so as to simultaneously improve the flame retardancy and dispersibility of modified montmorillonite.

[0005] The first aspect of this application provides a method for preparing modified montmorillonite, comprising the following steps:

[0006] A first modified montmorillonite intermediate was prepared by reacting γ-aminopropyltriethoxysilane with montmorillonite in a first reaction.

[0007] The cerium salt is mixed with the first modified montmorillonite intermediate in the presence of the first solvent to carry out a second reaction, thereby preparing the second modified montmorillonite intermediate.

[0008] Phosphorous acid and a second modified montmorillonite intermediate are mixed in the presence of a second solvent to carry out a third reaction, thereby preparing the modified montmorillonite.

[0009] In some embodiments, the mass ratio of the γ-aminopropyltriethoxysilane to the montmorillonite is (2-3):(8-10).

[0010] In some implementations, the conditions for the first reaction include a pH of 5.0-5.5.

[0011] In some implementations, the conditions for the first reaction include: a temperature of 60°C-80°C and a time of 5-6 hours.

[0012] In some embodiments, the step of carrying out the first reaction with γ-aminopropyltriethoxysilane and montmorillonite specifically includes:

[0013] After hydrolyzing γ-aminopropyltriethoxysilane, it is mixed with an ethanol-water solution of montmorillonite to carry out the first reaction.

[0014] In some embodiments, the volume ratio of ethanol to water in the montmorillonite aqueous solution is (1-2):(1-2).

[0015] In some embodiments, the step of hydrolyzing γ-aminopropyltriethoxysilane specifically includes:

[0016] γ-aminopropyltriethoxysilane was dissolved in anhydrous ethanol, water was added, and the mixture was stirred at 20℃-30℃ for 10-15 minutes to carry out hydrolysis.

[0017] In some embodiments, in the step of hydrolyzing γ-aminopropyltriethoxysilane, the volume ratio of anhydrous ethanol to water is (90-100):(3-5).

[0018] In some embodiments, the hydrolysis of γ-aminopropyltriethoxysilane is carried out under the following conditions: the mass-to-volume ratio of γ-aminopropyltriethoxysilane to anhydrous ethanol is (0.2 g - 0.4 g): 1 mL.

[0019] In some embodiments, the cerium salt includes CeCl3.

[0020] In some embodiments, the ratio of the total molar amount of montmorillonite cation exchange in the modified montmorillonite intermediate to the molar amount of cerium ions in the cerium salt is (1-1.5):(1-2).

[0021] In some embodiments, the first solvent includes water.

[0022] In some embodiments, the conditions for the second reaction include: a reaction temperature of 30°C-40°C and a reaction time of 1-1.5 hours.

[0023] In some embodiments, the molar ratio of the cerium salt to the phosphorous acid is (1-1.2):(3-3.5).

[0024] In some embodiments, the second solvent includes water.

[0025] In some embodiments, the conditions for the third reaction include: a reaction temperature of 50°C-60°C and a reaction time of 3-4 hours.

[0026] In a second aspect, this application provides a modified montmorillonite prepared by the method for preparing modified montmorillonite described in the first aspect.

[0027] The third aspect of this application provides the application of modified montmorillonite prepared by the method described in the first aspect in polyamide composites.

[0028] In a fourth aspect, this application provides a polyamide composite material comprising the following components in parts by weight:

[0029] 60-92 parts polyamide resin, 8-10 parts flame retardant, and 0.2-0.5 parts additives;

[0030] The flame retardant is modified montmorillonite prepared by the method described in the first aspect.

[0031] In some embodiments, the polyamide resin includes polycaprolactam and / or polyhexamethylene adipamide.

[0032] In some embodiments, the polyamide composite material further includes a reinforcing agent.

[0033] In some embodiments, the reinforcing agent in the polyamide composite material is 30 parts by mass.

[0034] In some embodiments, the reinforcing agent comprises glass fiber.

[0035] In some embodiments, the glass fiber comprises long glass fibers.

[0036] In some embodiments, the additives include at least one of antioxidants and lubricants.

[0037] In some embodiments, the polyamide composite material includes 0.2 parts by weight of an antioxidant.

[0038] In some embodiments, the antioxidant includes antioxidant 1010.

[0039] In some embodiments, the polyamide composite material includes 0.3 parts by weight of lubricant.

[0040] In some embodiments, the lubricant comprises vinyl bis-stearamide.

[0041] Compared with traditional technologies, this application has at least the following beneficial effects:

[0042] This application prepares a modified montmorillonite intermediate by using γ-aminopropyltriethoxysilane and montmorillonite in a first reaction, which enables the pre-intercalation of γ-aminopropyltriethoxysilane, expands the interlayer spacing of montmorillonite, and reduces the interlayer forces of montmorillonite. Further, a cerium salt is mixed with the first modified montmorillonite intermediate in the presence of a first solvent to carry out a second reaction. The amino group in the γ-aminopropyltriethoxysilane can anchor cerium ions, providing sites for the in-situ generation of cerium phosphite, further widening the interlayer spacing of montmorillonite. Then, phosphorous acid is mixed with a second modified montmorillonite intermediate in the presence of a second solvent to carry out a third reaction, generating cerium phosphite in-situ between the layers of the modified montmorillonite intermediate, thus preparing a modified montmorillonite with co-intercalation of γ-aminopropyltriethoxysilane and cerium phosphite, which can significantly improve the dispersibility and flame retardant properties of montmorillonite. Attached Figure Description

[0043] To better describe and illustrate the embodiments or examples provided in this application, reference may be made to one or more accompanying drawings. Additional details or examples used to describe the drawings should not be considered as limiting the scope of any of the disclosed applications, the currently described embodiments or examples, or the best mode of conduct of these applications as currently understood. Furthermore, the same reference numerals denote the same parts throughout the drawings.

[0044] Figure 1 A schematic diagram of scanning electron microscopy observation combined with EDS test results of modified montmorillonite; where A represents the EDS layered image of modified montmorillonite, B represents the elemental distribution map of Ce in the material, and C represents the EDS energy spectrum of modified montmorillonite.

[0045] Figure 2 The XRD pattern of Na-MMT;

[0046] Figure 3 XRD pattern of modified montmorillonite;

[0047] Figure 4 This is a schematic diagram showing the comparison between the XRD spectrum of Na-MMT and the standard XRD spectrum in the database.

[0048] Figure 5 A schematic diagram showing the comparison between the XRD pattern of modified montmorillonite and the standard XRD pattern in the database;

[0049] Figure 6 This is a schematic diagram of the FT-IR test results for modified montmorillonite. Detailed Implementation

[0050] The present application will be further described in detail below with reference to the embodiments and examples. These embodiments and examples are for illustrative purposes only and are not intended to limit the scope of the present application. The purpose of providing these embodiments and examples is to enable a more thorough and comprehensive understanding of the disclosure of the present application. It should also be understood that the present application can be implemented in many different forms and is not limited to the embodiments and examples described herein. Those skilled in the art can make various modifications or alterations without departing from the spirit of the present application, and the equivalent forms obtained also fall within the protection scope of the present application. Furthermore, numerous specific details are set forth in the following description to provide a fuller understanding of the present application. It should be understood that the present application can be implemented without one or more of these details.

[0051] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0052] To address the issues of low flame retardant efficiency and poor dispersibility in modified montmorillonite prepared by traditional methods, this application proposes a modified montmorillonite intermediate prepared by a first reaction involving γ-aminopropyltriethoxysilane and montmorillonite. This allows for the pre-intercalation of γ-aminopropyltriethoxysilane, expanding the interlayer spacing of montmorillonite and reducing interlayer forces. Furthermore, a cerium salt is mixed with the first modified montmorillonite intermediate in the presence of a first solvent for a second reaction. The amino groups in the γ-aminopropyltriethoxysilane anchor cerium ions, providing sites for the in-situ formation of cerium phosphite, further widening the interlayer spacing of montmorillonite. Then, phosphorous acid is mixed with a second modified montmorillonite intermediate in the presence of a second solvent for a third reaction, generating cerium phosphite in-situ between the layers of the modified montmorillonite intermediate. This process prepares a modified montmorillonite with co-intercalation of γ-aminopropyltriethoxysilane and cerium phosphite, significantly improving the dispersibility and flame retardant properties of montmorillonite.

[0053] The first aspect of this application provides a method for preparing modified montmorillonite, comprising the following steps:

[0054] A first modified montmorillonite intermediate was prepared by reacting γ-aminopropyltriethoxysilane with montmorillonite in a first reaction.

[0055] The cerium salt is mixed with the first modified montmorillonite intermediate in the presence of the first solvent to carry out a second reaction, thereby preparing the second modified montmorillonite intermediate.

[0056] Phosphorous acid and a second modified montmorillonite intermediate are mixed in the presence of a second solvent to carry out a third reaction, thereby preparing the modified montmorillonite.

[0057] This application prepares a modified montmorillonite intermediate by using γ-aminopropyltriethoxysilane and montmorillonite in a first reaction, which enables the pre-intercalation of γ-aminopropyltriethoxysilane, expands the interlayer spacing of montmorillonite, and reduces the interlayer forces of montmorillonite. Further, cerium salt is mixed with the first modified montmorillonite intermediate in the presence of a first solvent to carry out a second reaction. The amino group in γ-aminopropyltriethoxysilane can anchor cerium ions, providing sites for the in-situ generation of cerium phosphite, further widening the interlayer spacing of montmorillonite. Then, phosphorous acid is mixed with a second modified montmorillonite intermediate in the presence of a second solvent to carry out a third reaction, generating cerium phosphite in-situ between the layers of the modified montmorillonite intermediate, thus preparing a modified montmorillonite with γ-aminopropyltriethoxysilane and cerium phosphite co-intercalated. This constructs an integrated montmorillonite-based composite flame retardant structure integrating "interfacial modification-flame retardant activity-layered barrier," which can significantly improve the dispersibility and flame retardant properties of montmorillonite. Cerium phosphite, as an intercalating agent containing dual active components of phosphorus and rare earth elements, possesses both the flame-retardant activity of phosphorus and the catalytic char formation and smoke-suppressing activity of cerium. The two work synergistically to form a dual flame-retardant effect of "gas-phase quenching + dense char layer barrier". By loading the dual active components of phosphorus and rare earth elements between montmorillonite sheets through co-intercalation, it is beneficial to achieve the integration of "carrier + synergistic flame retardancy".

[0058] In this application, the chemical formula of cerium phosphate is Ce2(HPO3)3, and the water is deionized water.

[0059] In some embodiments, the mass ratio of the γ-aminopropyltriethoxysilane to the montmorillonite is (2-3):(8-10), which can be 2:8, 2:9, 2:10, 2.5:8, 2.5:9, 2.5:10, 3:8, 3:9 or 3:10.

[0060] In some embodiments, the montmorillonite is sodium-based montmorillonite.

[0061] In some implementations, the conditions for the first reaction include a pH of 5.0-5.5.

[0062] In some embodiments, the conditions for the first reaction include: a temperature of 60°C-80°C, which can be 60°C, 65°C, 70°C, 75°C or 80°C; and a time of 5h-6h, which can be 5h, 5.2h, 5.5h, 5.8h or 6h.

[0063] In some embodiments, the step of carrying out the first reaction with γ-aminopropyltriethoxysilane and montmorillonite specifically includes:

[0064] After hydrolyzing γ-aminopropyltriethoxysilane, it is mixed with an ethanol-water solution of montmorillonite to carry out the first reaction.

[0065] In this application, γ-aminopropyltriethoxysilane is hydrolyzed to produce silanol groups, which are then condensed with hydroxyl groups on the surface of montmorillonite to achieve pre-intercalation of γ-aminopropyltriethoxysilane between montmorillonite sheets.

[0066] In some embodiments, the step of hydrolyzing γ-aminopropyltriethoxysilane specifically includes:

[0067] Dissolve γ-aminopropyltriethoxysilane in anhydrous ethanol, add water, and hydrolyze by stirring at 20℃-30℃ for 10-15 minutes. Hydrolysis can also be carried out by stirring at 25℃ for 10-15 minutes.

[0068] In some embodiments, the γ-aminopropyltriethoxysilane is hydrolyzed, specifically including the following steps:

[0069] Dissolve γ-aminopropyltriethoxysilane in anhydrous ethanol, then add water dropwise at a rate of 1 mL / min. The volume ratio of the anhydrous ethanol to the water is (90-100):(3-5), which can be 90:3, 90:4, 90:5, 95:3, 95:4, 95:5, 100:3, 100:4, or 100:5. Then, stir at 20℃-30℃ for 10 min to carry out hydrolysis. Hydrolysis can be carried out at 20℃, 25℃, or 30℃ for 10 min.

[0070] In some embodiments, in the step of hydrolyzing γ-aminopropyltriethoxysilane, the volume ratio of anhydrous ethanol to water is (90-100):(3-5), which can be 90:3, 90:4, 90:5, 95:3, 95:4, 95:5, 100:3, 100:4 or 100:5.

[0071] In some embodiments, the hydrolysis conditions include a mass-to-volume ratio of γ-aminopropyltriethoxysilane to anhydrous ethanol of (0.2g-0.4g):1mL, which can be 0.2g:1mL, 0.25g:1mL, 0.3g:1mL, 0.35g:1mL, or 0.4g:1mL.

[0072] In some embodiments, the volume ratio of ethanol to water in the montmorillonite aqueous solution is (1-2):(1-2), which can be 1:1, 1:1.5, 1:2 or 2:1.

[0073] In some embodiments, the ethanol-water solution of montmorillonite is prepared by the following method:

[0074] Montmorillonite was mixed with an ethanol-water mixture and then subjected to ultrasonic treatment. The ultrasonic conditions included: ultrasonic power of 350W-450W (350W, 370W, 400W, 420W, or 450W); working mode of "working for 3s-5s-stopping for 1s-2s" (3s-2s); and ultrasonic time of 30min-40min (30min, 31min, 32min, 33min, 34min, 35min, 36min, 37min, 38min, 39min, or 40min) to prepare an ethanol-water solution of montmorillonite.

[0075] In some embodiments, the cerium salt includes CeCl3.

[0076] In some embodiments, the CeCl3 solution is an aqueous solution of CeCl3.

[0077] In some embodiments, the ratio of the total molar amount of montmorillonite cation exchange in the modified montmorillonite intermediate to the molar amount of cerium ions in the cerium salt is (1-1.5):(1-2), which can be 1:1, 1:1.5, 1:2, 1.5:1 or 1.5:2.

[0078] In some embodiments, the first solvent includes water.

[0079] In some embodiments, the conditions for the second reaction include: a temperature of 30°C-40°C, which can be 30°C, 31°C, 32°C, 33°C, 34°C, 35°C, 36°C, 37°C, 38°C, 39°C, or 40°C; and a time of 1h-1.5h, which can be 1h, 1.1h, 1.2h, 1.3h, 1.4h, or 1.5h.

[0080] In some embodiments, in the step of mixing the cerium salt with the first modified montmorillonite intermediate in the presence of a first solvent to carry out a second reaction, the concentration of the cerium salt in the reaction system of the second reaction is 0.03 mmol / mL-0.04 mmol / mL, and can be 0.03 mmol / mL, 0.031 mmol / mL, 0.032 mmol / mL, 0.033 mmol / mL, 0.034 mmol / mL, 0.035 mmol / mL, 0.036 mmol / mL, 0.037 mmol / mL, 0.038 mmol / mL, 0.039 mmol / mL or 0.04 mmol / mL.

[0081] In some embodiments, the step of mixing the cerium salt with the first modified montmorillonite intermediate in the presence of a first solvent specifically includes:

[0082] A cerium salt solution is prepared by dissolving a portion of the cerium salt in a first solvent; the concentration of the cerium salt solution is 0.4 mmol / mL to 0.5 mmol / mL, and may be 0.4 mmol / mL, 0.41 mmol / mL, 0.42 mmol / mL, 0.43 mmol / mL, 0.44 mmol / mL, 0.45 mmol / mL, 0.46 mmol / mL, 0.47 mmol / mL, 0.48 mmol / mL, 0.49 mmol / mL, or 0.5 mmol / mL.

[0083] The first modified montmorillonite intermediate was dissolved in the remaining first solvent to prepare a first modified montmorillonite intermediate solution;

[0084] The cerium salt solution was added to the first modified montmorillonite intermediate solution and mixed.

[0085] In some embodiments, the molar ratio of the cerium salt to the phosphorous acid is (1-1.2):(3-3.5), which can be 1:3, 1.1:3, 1.2:3, 1:3.2, 1.1:3.2, 1.2:3.2, 1:3.5, 1.1:3.5, 1.2:3, 1.2:3.2, or 1.2:3.5.

[0086] In some embodiments, the second solvent includes water.

[0087] In some embodiments, in the step of mixing phosphorous acid with the second modified montmorillonite intermediate in the presence of a second solvent to carry out a third reaction, the concentration of phosphorous acid in the reaction system of the third reaction is 0.1 mmol / mL to 0.12 mmol / mL, which can be 0.1 mmol / mL, 0.11 mmol / mL or 0.12 mmol / mL.

[0088] In some embodiments, the step of mixing phosphorous acid with the second modified montmorillonite intermediate in the presence of a second solvent specifically includes:

[0089] The first modified montmorillonite intermediate is dissolved in part of the second solvent to form a first modified montmorillonite intermediate solution;

[0090] Phosphorous acid is dissolved in the remaining second solvent to prepare a phosphorous acid solution; the concentration of the phosphorous acid solution is 1 mmol / mL-1.5 mmol / mL, and can be 1 mmol / mL, 1.1 mmol / mL, 1.2 mmol / mL, 1.3 mmol / mL, 1.4 mmol / mL or 1.5 mmol / mL;

[0091] The phosphorous acid solution was added to the second modified montmorillonite intermediate solution and mixed.

[0092] In some embodiments, after mixing the cerium salt with the first modified montmorillonite intermediate in the presence of a first solvent and carrying out a second reaction, the process further includes washing the precipitate and drying it.

[0093] In some embodiments, after mixing the cerium salt with the first modified montmorillonite intermediate in the presence of a first solvent and carrying out a second reaction, the process further includes a step of washing the precipitate; the conditions for washing the precipitate include washing it sequentially with anhydrous ethanol and deionized water. In some embodiments, the conditions for the third reaction include: a reaction temperature of 50°C-60°C, which can be 50°C, 52°C, 55°C, 57°C, or 60°C; and a reaction time of 3h-4h, which can be 3h, 3.2h, 3.5h, or 4h.

[0094] In some embodiments, after the third reaction, the process further includes steps of filtration, washing, and drying.

[0095] In some embodiments, after the third reaction, the process further includes steps of filtration, washing, and drying; the washing conditions include washing until the pH of the filtrate is 6-7.

[0096] In some embodiments, after the third reaction, the process further includes steps of filtration, washing, and drying; the drying conditions include a temperature of 70°C.

[0097] In a second aspect, this application provides a modified montmorillonite prepared by the method for preparing modified montmorillonite described in the first aspect.

[0098] The third aspect of this application provides the application of modified montmorillonite prepared by the method described in the first aspect in polyamide composites.

[0099] In a fourth aspect, this application provides a polyamide composite material comprising the following components in parts by weight:

[0100] 60-92 parts polyamide resin, 8-10 parts flame retardant, and 0.2-0.5 parts additives;

[0101] The flame retardant is modified montmorillonite prepared by the method described in the first aspect or modified montmorillonite described in the second aspect.

[0102] Polyamide resin (PA), as a class of high-performance engineering plastics, possesses excellent mechanical strength, wear resistance, corrosion resistance, and electrical insulation properties, and is widely used in electronics, transportation, automotive parts, and precision instruments. However, polyamide resin has inherent flammability, with a limiting oxygen index (LOI) of only 20%-22%. When burning, it is accompanied by severe melting and dripping, which can easily cause the fire to spread, severely limiting its application in scenarios with stringent fire safety requirements.

[0103] Therefore, flame retardants are often introduced into polyamide composites to improve their flame retardant properties. However, traditional flame retardants used in polyamide composites have the drawbacks of high addition amount and poor dispersion, which seriously restricts the flame retardant properties, mechanical properties, electrical properties and thermal stability of polyamide composites, and cannot meet the requirements of high-end applications. For example, montmorillonite (MMT) alone has strong interlayer forces and a low intercalation rate, making it prone to agglomeration in polyamide resin matrices and difficult to disperse at the nanoscale. The flame retardant effect of the layered structure of montmorillonite is weak, requiring high addition levels to achieve the basic flame retardant rating, and it also cannot solve the problem of polyamide combustion dripping. Cerium phosphite flame retardant alone requires high addition levels (≥15%) to achieve flame retardant effect, but excessive addition of flame retardant will seriously degrade the tensile strength, impact toughness and other mechanical properties of polyamide composites. Silane coupling agent KH-550 contains amino groups at its molecular ends, which can form hydrogen bonds with polyamide resin molecular chains. At the same time, the alkoxy group at the other end can react with the hydroxyl groups on the surface of montmorillonite, which is beneficial to improving the compatibility between montmorillonite and polyamide resin. However, KH-550 alone can only improve the interfacial compatibility of polyamide composites without additional flame retardant activity. It requires additional compounding of a large amount of flame retardant to achieve flame retardancy. However, additional compounding causes a double deterioration in the system compatibility and processing suitability of polyamide composites. Therefore, traditional intercalated modified montmorillonite cannot simultaneously achieve the high flame retardancy, mechanical properties, and electrical properties of polyamide composites.

[0104] The polyamide composite material of this application uses the modified montmorillonite described in the first aspect, which can improve the mechanical properties, flame retardant properties, and electrical properties of the polyamide composite material. Specifically, the intercalation of KH-550 effectively expands the interlayer spacing of montmorillonite and strengthens its interfacial bonding with the polyamide resin, improving the problems of montmorillonite's tendency to agglomerate and poor compatibility. Simultaneously, the in-situ intercalation of cerium phosphite enables the loading of "phosphorus-rare earth" dual active components between the montmorillonite layers, synergistically constructing a triple flame retardant mechanism of "phosphorus-based gas-phase quenching + rare earth catalytic char formation + montmorillonite layered barrier" with KH-550 and montmorillonite. The modified montmorillonite, at low addition levels, enables the polyamide composite material to achieve V-0 flame retardancy (UL94 standard), limiting oxygen index ≥32%, CTI ≥600V, and retains ≥85% of mechanical properties such as tensile strength and impact toughness after adding the flame retardant, simultaneously achieving efficient smoke suppression, anti-melt dripping, and excellent processing stability and long-term durability.

[0105] In some embodiments, the polyamide resin in the polyamide composite material is 60-92 parts by weight, and can be 60, 65, 70, 75, 80, 85, 90 or 92 parts.

[0106] In some embodiments, the flame retardant in the polyamide composite material is 8-10 parts by mass, specifically 8, 8.5, 9, 9.5, or 10 parts. In the polyamide composite material described in this application, modified montmorillonite achieves a synergistic flame retardant effect through cerium phosphite intercalation within the montmorillonite layers, resulting in a triple effect of "gas-phase flame retardancy - condensed-phase flame retardancy - physical barrier." Specifically, cerium phosphite decomposes upon heating to generate PO· and HPO· free radicals, which can capture H· and OH· free radicals generated during the combustion of the polyamide resin, thereby interrupting the combustion chain reaction of the polyamide composite material. 3+ Lewis acid catalyzes the crosslinking and aromatization of polyamide resins, forming a dense carbon layer that blocks heat and oxygen. Montmorillonite sheets create a "maze effect" within the carbon layer, extending the heat / gas transfer path and enhancing the stability of the carbon layer.

[0107] In the polyamide composite material described in this application, the modified montmorillonite forms hydrogen bonds with the polyamide resin molecular chain through the amino group of KH-550. At the same time, its long organic chain reduces the interfacial tension between the flame retardant modified montmorillonite and the polyamide resin melt, reduces dispersion defects, and ensures the retention of the mechanical properties of the polyamide composite material.

[0108] In the polyamide composite material described in this application, modified montmorillonite blocks current conduction through its layered structure, cerium phosphite enhances the surface wear resistance of the polyamide composite material, and KH-550 improves the surface resistivity of the polyamide composite material. The three components work synergistically to improve the CTI performance of the polyamide composite material and achieve optimized electrical performance.

[0109] In some embodiments, the mass fraction of the additive in the polyamide composite material is 0.2-0.5 parts, which can be 0.2 parts, 0.3 parts, 0.4 parts or 0.5 parts.

[0110] In some embodiments, the polyamide resin includes polycaprolactam (PA6) and / or polyhexamethylene adipamide (PA66).

[0111] In some embodiments, the polyamide resin is PA6, which satisfies the following condition: relative viscosity at 25°C is 2.8.

[0112] In some embodiments, the polyamide resin is PA66, which satisfies the following condition: relative viscosity at 25°C is 2.9.

[0113] In some embodiments, the polyamide composite material further includes a reinforcing agent.

[0114] In some embodiments, the reinforcing agent in the polyamide composite material is 30 parts by mass.

[0115] In some embodiments, the reinforcing agent comprises glass fiber.

[0116] In some embodiments, the glass fiber comprises long glass fibers.

[0117] In some embodiments, the glass fiber comprises alkali-free glass fiber roving for thermoplastics of China Jushi Co., Ltd., grade 910A.

[0118] In some embodiments, the additives include at least one of antioxidants and lubricants.

[0119] In some embodiments, the polyamide composite material includes 0.2 parts by weight of an antioxidant.

[0120] In some embodiments, the antioxidant includes antioxidant 1010.

[0121] In some embodiments, the polyamide composite material includes 0.3 parts by weight of lubricant.

[0122] In some embodiments, the lubricant includes vinyl distearate (EBS).

[0123] In some embodiments, the additives are antioxidants and lubricants; in the polyamide composite material, the antioxidant is 0.2 parts by mass and the lubricant is 0.3 parts by mass.

[0124] In some embodiments, the polyamide composite material comprises the following components in parts by weight:

[0125] PA6 60-62 parts, flame retardant 8-10 parts, reinforcing agent 30 parts and additives 0.5 parts;

[0126] Wherein, the flame retardant is modified montmorillonite prepared by the method described in the first aspect;

[0127] The additives include antioxidants and lubricants.

[0128] In some embodiments, the polyamide composite material comprises the following components in parts by weight:

[0129] PA6 90-92 parts, flame retardant 8-10 parts and additives 0.5 parts;

[0130] Wherein, the flame retardant is modified montmorillonite prepared by the method described in the first aspect;

[0131] The additives include antioxidants and lubricants.

[0132] In some embodiments, the polyamide composite material comprises the following components in parts by weight:

[0133] PA66 60-62 parts, flame retardant 8-10 parts, reinforcing agent 30 parts and additives 0.5 parts;

[0134] Wherein, the flame retardant is modified montmorillonite prepared by the method described in the first aspect;

[0135] The additives include antioxidants and lubricants.

[0136] In some embodiments, the polyamide composite material comprises the following components in parts by weight:

[0137] PA66 90-92 parts, flame retardant 8-10 parts and additives 0.5 parts;

[0138] Wherein, the flame retardant is modified montmorillonite prepared by the method described in the first aspect;

[0139] The additives include antioxidants and lubricants.

[0140] In some embodiments, the polyamide composite material is prepared by the following method:

[0141] The components are mixed and melt-extruded to prepare the polyamide composite material.

[0142] In some embodiments, the process of drying the components is included before mixing them.

[0143] In some embodiments, the mixing conditions for each component include: a mixing temperature of 20°C-30°C, which can be 20°C, 22°C, 25°C, 27°C, or 30°C; a rotation speed of 800 r / min-2000 r / min, which can be 800 r / min, 1000 r / min, 1500 r / min, or 2000 r / min; and a mixing time of 5 min-8 min, which can be 5 min, 6 min, 7 min, or 8 min.

[0144] In the following embodiments, the melt extrusion conditions include: melt extrusion using a twin-screw extruder with a screw speed of 280 r / min-350 r / min, which can be 280 r / min, 290 r / min, 300 r / min, 310 r / min, 320 r / min, 330 r / min, 340 r / min or 350 r / min.

[0145] In some embodiments, the polyamide resin in the polyamide composite material is PA6, and in the step of melt extrusion using a twin-screw extruder, the processing temperature of the twin-screw extruder is 230℃-250℃; the processing temperature of each zone in the twin-screw extruder can be set as follows: Zone 1 230℃, Zone 2 240℃, Zone 3 250℃, and Die Head 245℃.

[0146] In some embodiments, the polyamide resin in the polyamide composite material is PA66, and in the step of melt extrusion using a twin-screw extruder, the processing temperature of the twin-screw extruder is 250℃-270℃; the processing temperature of each zone in the twin-screw extruder can be set as follows: Zone 1 250℃, Zone 2 260℃, Zone 3 270℃, and Die Head 265℃.

[0147] The embodiments of this application will be described in detail below with reference to examples. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of this application. For experimental methods in the following embodiments where specific conditions are not specified, please refer to the guidelines given in this application, or follow experimental manuals or conventional conditions in the art, or follow the conditions recommended by the manufacturer, or refer to experimental methods known in the art.

[0148] The raw materials used in this embodiment are as follows:

[0149] Sodium-based montmorillonite (Na-MMT): Cation exchange capacity (CEC) ≈ 100 mmol / 100 g, dried and passed through a 300-mesh sieve;

[0150] γ-aminopropyltriethoxysilane (KH-550): analytical grade;

[0151] Cerium chloride hexahydrate (CeCl3·6H2O): analytical grade;

[0152] Phosphorous acid (H3PO3): analytical grade;

[0153] Auxiliary reagents: anhydrous ethanol (analytical grade), 0.1 mol / L dilute hydrochloric acid, deionized water.

[0154] Example 1

[0155] The preparation method of modified montmorillonite is as follows:

[0156] (1) Weigh 20g Na-MMT (total cation exchange capacity is 20mmol), add 100mL 50% ethanol-water mixed solution (volume ratio of ethanol to water is 1:1), place it in an ultrasonic cell disruptor, and sonicate for 40min at 400W power and "work 3s-stop 2s" mode to form a uniform suspension and obtain sodium montmorillonite ethanol aqueous solution.

[0157] Weigh 6g of KH-550 (27mmol, the mass ratio of KH-550 to Na-MMT is 3:10), dissolve it in 20mL of anhydrous ethanol, add 12 drops of deionized water (0.6mL), and stir at room temperature (25℃) for 10min to hydrolyze the solution and prepare the hydrolyzed KH-550 solution.

[0158] 0.1 mol / L dilute hydrochloric acid was added dropwise to the prepared sodium-based montmorillonite aqueous solution to adjust the pH of the system to 5.0-5.5. The solution was then transferred to a thermostatic magnetic stirrer, heated to 60℃, and stirred at 300 r / min. Simultaneously, the hydrolyzed KH-550 solution was slowly added dropwise at a rate of 1 mL / min. After the addition was complete, the mixture was kept at this temperature and stirred for 5 h to carry out the first reaction. After the reaction was completed, the reaction solution was poured into a pre-wetted Buchner funnel, filtered, and the precipitate was collected. The precipitate was then washed with 50 mL of anhydrous ethanol, and the washing was repeated 3 times to remove free KH-550. Finally, the solution was rinsed once with deionized water to prepare the wet first modified montmorillonite intermediate (KH550-MMT), in which the total cation exchange capacity of montmorillonite was 20 mmol.

[0159] (2) Add the wet first modified montmorillonite intermediate prepared in step 1 to 500 mL of deionized water and sonicate at 300 W power for 30 min to disperse it into a uniform suspension of the first modified montmorillonite intermediate.

[0160] Based on 1.0 times the CEC (cation exchange capacity) of Na-MMT, weigh 7.09 g CeCl3·6H2O (20 mmol), dissolve it in 50 mL of deionized water, and prepare a cerium salt solution.

[0161] According to Ce 3+ With a molar ratio of 1:3 to phosphorous acid, weigh 4.86 g of phosphorous acid (H3PO3, 60 mmol) and prepare a phosphorous acid solution with 50 mL of deionized water;

[0162] A cerium salt solution was added dropwise to the suspension of the first modified montmorillonite intermediate at a rate of 1 mL / min. The mixture was stirred at 300 r / min for 1 h at 30 °C to carry out the second reaction, preparing the second modified montmorillonite intermediate. This was achieved through the reaction of the amino group of KH-550 with Ce. 3+ Coordination adsorption to achieve Ce 3+ Anchoring; then slowly add phosphorous acid solution, stir for 10 min, and check the pH in the range of 3.5-4.5. No additional pH adjustment is needed. Raise the temperature to 50℃ to carry out the third reaction, and keep the reaction at this temperature with stirring for 3 h to allow Ce to be anchored. 3+ With HPO3 2- Cerium phosphite (chemical formula Ce2(HPO3)3) was generated in situ between the layers of the modified montmorillonite intermediate. After the reaction was completed, the reaction solution was filtered and the precipitate was collected. The precipitate was repeatedly washed with deionized water until the pH of the filtrate was 6-7. Then the precipitate was placed in a vacuum drying oven and dried at 70°C for 10 h. After grinding, modified montmorillonite with KH-550 and cerium phosphite co-intercalated was obtained.

[0163] The Na-MMT, the prepared modified montmorillonite intermediate, and the prepared modified montmorillonite were observed by scanning electron microscopy, as well as by energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR) to verify the intercalation effect of KH-550 and cerium phosphate.

[0164] The XRD test conditions were as follows: Cu Kα rays (incident wavelength of 0.154 nm), scanning range 2θ = 1~85°, step size 2°.

[0165] The Fourier transform infrared spectrometer (FT-IR) has a detection wavenumber range of 4000–400 cm⁻¹. -1 .

[0166] The scanning electron microscopy observations combined with EDS test results of the modified montmorillonite are shown in Figure 1. Figure 1 In the image, A represents the EDS layered image of modified montmorillonite, B represents the elemental distribution map of Ce, and C represents the EDS energy spectrum of modified montmorillonite. From... Figure 1 As can be seen, the modified montmorillonite particles contain a large number of cerium and phosphorus ions, proving that the cerium phosphite intercalation was successful.

[0167] XRD test results are as follows Figures 2-3 As shown, where, Figure 2 The image shows the XRD pattern of Na-MMT. Figure 3 The image shows the XRD pattern of modified montmorillonite. Figures 2-3 It can be seen that Na-MMT exhibits a strong diffraction peak at 2θ=5.7°, while the strong diffraction peak of the prepared modified montmorillonite shifts to 2θ=4.95°. Based on the Bragg equation nλ=2dsinθ (n=1; d is the interlayer spacing of montmorillonite, i.e., the distance between the (001) planes; λ is the wavelength of the incident ray), the interlayer spacing of montmorillonite is calculated. The calculated interlayer spacing of Na-MMT is 1.55 nm, and that of the modified montmorillonite is 1.78 nm. Among these, Ce... 3+ Both the ionic radius and hydration radius of Na are greater than those of Na. + Ce 3+ The insertion of ions increases the interlayer spacing of montmorillonite. The XRD pattern of Na-MMT was compared with standard XRD patterns in the database, and the results are as follows... Figure 4 As shown, it can be seen that Na-MMT (such as Figure 4 The compound matched by Na-MMT is sodium aluminosilicate (Na) 23 Al 23 Si 25 O 96 ) and low-alumina feldspar (Na(AlSi3O8)), which together constitute the chemical composition of Na-MMT, Na 23 Al 23 Si25 O 96 (like Figure 4 As shown in Figure A) and Na(AlSi3O8) (as shown in Figure A) Figure 4 The semi-quantitative results for (as shown in Figure B) were 80.5 wt% and 19.5 wt%, respectively. The XRD patterns of the modified montmorillonite (as shown in the figure) were compared with standard XRD patterns in the database, and the results are as follows: Figure 5 As shown, lanthanum phosphite (H3La(PHO3)3(H2O) (as shown) Figure 5 The semi-quantitative proportion of Li2(Al,Fe,Mg)5Si8O (as shown in Figure B) was 80.89 wt%. 22 (OH)2 (such as) Figure 5 (as shown in A) and Mg 5.16 Al 10.32 Si 37.68 O 96 (like Figure 5 The sum of the semi-quantitative proportions (shown in C) is 19.11 wt%. Since the standard spectra of cerium compounds in the XRD database are incomplete, and cerium salts rather than lanthanum salts are used in the preparation of modified montmorillonite, and since cerium and lanthanum both belong to the lanthanide series and have similar electronic configurations, combined with the EDS energy spectrum of modified montmorillonite, the lanthanum phosphite in modified montmorillonite should be cerium phosphite.

[0168] The FT-IR test results of Na-MMT and modified montmorillonite are as follows: Figure 6 As shown, the FT-IR test results of modified montmorillonite at 1030 cm⁻¹ indicate that... -1 The characteristic peak of stretching vibration belonging to the CN bond in KH-550 appears at 1600 cm⁻¹. -1 The presence of bending vibration characteristic peaks at 1050 cm⁻¹, attributed to the NH bonds in KH-550, proves the successful intercalation of KH-550 in montmorillonite; the modified montmorillonite at 1050 cm⁻¹... -1 -1150cm -1 The presence of a characteristic peak representing the stretching vibration of phosphate (PO bond) at 3620 cm⁻¹ confirms successful intercalation of cerium phosphate in montmorillonite. Comparing the FT-IR spectra of Na-MMT and modified montmorillonite, it can be seen that the stretching vibration absorption peak of the interlayer hydroxyl (-OH) group in Na-MMT is at 3620 cm⁻¹. -1 Around 1000 saturates, after KH-550 is intercalated into the interlayer of montmorillonite to prepare modified montmorillonite, KH-550 interacts with the hydroxyl groups in the montmorillonite interlayers through silanol groups. Simultaneously, KH-550 is anchored to cerium ions through amino groups, resulting in a red shift of the absorption peak towards lower wavenumbers, a decrease in peak intensity, and a broadening of the peak shape. The stretching vibration absorption peak of the silicon-oxygen tetrahedron (Si-O-Si) in Na-MMT is at 1040 cm⁻¹. -1 -1050cm -1Its antisymmetric stretching vibration peak is at 1110 cm⁻¹ -1 The introduction of cerium ions into the interlayer of modified montmorillonite alters the interlayer environment, causing a slight shift in these two peaks and a decrease in peak intensity. The stretching vibration absorption peak of adsorbed water in the interlayer of Na-MMT is at 3400 cm⁻¹. -1 -3500cm -1 Its bending vibration peak is at 1630 cm. -1 The cerium ions introduced into the interlayer of modified montmorillonite will occupy part of the space between the montmorillonite layers, reducing the content of adsorbed water, and the intensity of the two peaks of adsorbed water will be significantly reduced.

[0169] Example 2

[0170] The preparation method of modified montmorillonite is as follows:

[0171] (1) Weigh 20g Na-MMT (total cation exchange capacity is 20mmol), add 100mL 50% ethanol-water mixed solution (volume ratio of ethanol to water is 1:1), place it in an ultrasonic cell disruptor, and sonicate for 30min at 450W power and "work 5s-stop 2s" mode to form a uniform suspension and obtain sodium montmorillonite ethanol aqueous solution.

[0172] Weigh 6g of KH-550 (27mmol, the mass ratio of KH-550 to Na-MMT is 3:10), dissolve it in 20mL of anhydrous ethanol, add 12 drops of deionized water (0.6mL), and stir at room temperature (25℃) for 10min to hydrolyze the solution and prepare the hydrolyzed KH-550 solution.

[0173] 0.1 mol / L dilute hydrochloric acid was added dropwise to the prepared sodium-based montmorillonite aqueous solution to adjust the pH of the system to 5.0-5.5. The solution was then transferred to a thermostatic magnetic stirrer, heated to 60℃, and stirred at 300 r / min. Simultaneously, the hydrolyzed KH-550 solution was slowly added dropwise at a rate of 1 mL / min. After the addition was complete, the mixture was kept at this temperature and stirred for 5 h to carry out the first reaction. After the reaction was completed, the reaction solution was poured into a pre-wetted Buchner funnel, filtered, and the precipitate was collected. The precipitate was then washed with 50 mL of anhydrous ethanol, and the washing was repeated 3 times to remove free KH-550. Finally, the solution was rinsed once with deionized water to prepare the wet first modified montmorillonite intermediate (KH550-MMT), in which the total cation exchange capacity of montmorillonite was 20 mmol.

[0174] (2) Add the wet first modified montmorillonite intermediate prepared in step 1 to 500 mL of deionized water and sonicate at 300 W power for 30 min to disperse it into a uniform suspension of the first modified montmorillonite intermediate.

[0175] Based on the calculation of 1.2 times the CEC (cation exchange capacity) of Na-MMT, weigh 8.51 g CeCl3·6H2O (24 mmol), dissolve it in 50 mL of deionized water, and prepare a cerium salt solution;

[0176] According to Ce 3+ With a molar ratio of 1:3 to phosphorous acid, weigh 5.83 g of phosphorous acid (H3PO3, 72 mmol) and prepare a phosphorous acid solution with 50 mL of deionized water;

[0177] A cerium salt solution was added dropwise to the suspension of the first modified montmorillonite intermediate at a rate of 1 mL / min. The mixture was stirred at 300 r / min for 1 h at 40 °C to carry out the second reaction, preparing the second modified montmorillonite intermediate. This was achieved through the reaction of the amino group of KH-550 with Ce. 3+ Coordination adsorption to achieve Ce 3+ Anchoring; then slowly add phosphorous acid solution, stir for 10 min, and check the pH to be within the range of 3.5-4.5. No additional pH adjustment is needed. Raise the temperature to 50℃ to carry out the third reaction, and keep the reaction at this temperature with stirring for 3.5 h to allow Ce to be anchored. 3+ With HPO3 2- Cerium phosphite (chemical formula Ce2(HPO3)3) was generated in situ between the layers of the modified montmorillonite intermediate. After the reaction was completed, the reaction solution was filtered and the precipitate was collected. The precipitate was repeatedly washed with deionized water until the pH of the filtrate was 6-7. Then the precipitate was placed in a vacuum drying oven and dried at 70°C for 10 h. After grinding, modified montmorillonite with KH-550 and cerium phosphite co-intercalated was obtained.

[0178] Comparative Example 1

[0179] The preparation method for KH-550 surface-modified montmorillonite is as follows:

[0180] Weigh 20g Na-MMT (total cation exchange capacity of 20mmol), add 100mL of 50% ethanol-water mixed solution (volume ratio of ethanol to water is 1:1), place it in an ultrasonic cell disruptor, and sonicate for 40min at 400W power in "work 3s-stop 2s" mode to form a uniform suspension, thus obtaining an ethanol aqueous solution of sodium montmorillonite.

[0181] Weigh 6g of KH-550 (27mmol, the mass ratio of KH-550 to Na-MMT is 3:10), dissolve it in 20mL of anhydrous ethanol, add 12 drops of deionized water (0.6mL), and stir at room temperature (25℃) for 10min to hydrolyze the solution and prepare the hydrolyzed KH-550 solution.

[0182] Add 0.1 mol / L dilute hydrochloric acid dropwise to the prepared sodium-based montmorillonite aqueous solution to adjust the pH of the system to 5.0-5.5. Transfer the solution to a constant temperature magnetic stirrer, heat to 60℃, stir at 300 r / min, and simultaneously slowly add the prepared hydrolyzed KH-550 solution dropwise at a rate of 1 mL / min. After the addition is complete, continue to keep the solution warm and stir for 5 h to carry out the first reaction. After the reaction is completed, pour the reaction solution into a pre-wetted Buchner funnel, filter and collect the precipitate, then wash the precipitate with 50 mL of anhydrous ethanol, repeat the washing 3 times to remove free KH-550, and finally rinse once with deionized water to prepare the wet first modified montmorillonite (KH550-MMT). Place it in a vacuum drying oven and dry at 80℃ for 8 h. Grind to obtain KH-550 surface-modified montmorillonite.

[0183] Comparative Example 2

[0184] The preparation method for cerium phosphite-intercalated modified montmorillonite is as follows:

[0185] Weigh 20g Na-MMT (total cation exchange capacity of 20mmol), add 100mL of 50% ethanol-water mixed solution (volume ratio of ethanol to water is 1:1), place it in an ultrasonic cell disruptor, and sonicate for 40min at 400W power in "work 3s-stop 2s" mode to form a uniform suspension, thus obtaining an ethanol aqueous solution of sodium montmorillonite.

[0186] Based on 1.0 times the CEC (cation exchange capacity) of Na-MMT, weigh 7.09 g CeCl3·6H2O (20 mmol), dissolve it in 50 mL of deionized water, and prepare a cerium salt solution.

[0187] According to Ce 3+ With a molar ratio of 1:3 to phosphorous acid, weigh 4.86 g of phosphorous acid (H3PO3, 60 mmol) and prepare a phosphorous acid solution with 50 mL of deionized water;

[0188] Cerium salt solution was added dropwise to an ethanol-water solution of sodium montmorillonite at a rate of 1 mL / min, and stirred at 300 r / min for 1 h at 30 °C. Then, phosphorous acid solution was slowly added dropwise to the reaction system, and the mixture was stirred for 10 min. The pH was monitored and found to be within the range of 3.5-4.5, requiring no additional pH adjustment. The temperature was raised to 50 °C for the third reaction, and the reaction was maintained at this temperature with stirring for 3 h. The cerium salt solution was then added dropwise to an ethanol-water solution of sodium montmorillonite at 300 r / min for 1 h. 3+ With HPO3 2-Cerium phosphite (chemical formula Ce2(HPO3)3) was generated in situ between the layers of the modified montmorillonite intermediate. After the reaction was completed, the reaction solution was filtered and the precipitate was collected. The precipitate was repeatedly washed with deionized water until the pH of the filtrate was 6-7. Then the precipitate was placed in a vacuum drying oven and dried at 70°C for 10 h. After grinding, cerium phosphite-intercalated modified montmorillonite was obtained.

[0189] Application Example 1

[0190] The polyamide composite material is composed of the following components in parts by weight:

[0191] 92 parts PA6 granules, 8 parts composite flame retardant and 0.5 parts additives (the additives consist of 0.2 parts antioxidant 1010 and 0.3 parts lubricant EBS).

[0192] Among them, the PA6 particles are PA6 material of model N6100 from Guangdong Qide New Material Co., Ltd.;

[0193] The composite flame retardant is the modified montmorillonite prepared in Example 1.

[0194] The preparation method of polyamide composite material is as follows:

[0195] PA6 granules were dried in an 80℃ vacuum drying oven for 4 hours to remove moisture (to avoid hydrolysis during processing); the composite flame retardant (modified montmorillonite) and additives were dried at room temperature for 2 hours.

[0196] Add each component to a high-speed mixer according to the formula ratio, and stir and mix at room temperature (25℃) and 1000r / min for 5 minutes to prepare a mixture.

[0197] The mixture is added to a twin-screw extruder, and the twin-screw extruder parameters are set as follows: screw speed is 300 r / min, processing temperature: zone 1 230℃, zone 2 240℃, zone 3 250℃, die head 245℃); after melt blending, it is extruded and granulated to produce a polyamide composite material.

[0198] The polyamide composite material was vacuum dried at 80℃ for 2 hours, and then injection molded into standard test specimens using an injection molding machine. The injection temperature was set to 245℃, the injection pressure to 90MPa, and the holding time to 18s.

[0199] Test strip preparation: Prepare 1.6 mm thick strips according to UL94 standard and test their vertical flammability rating. Prepare 80 mm × 10 mm × 4 mm strips according to ISO 4589-2 standard and test their limiting oxygen index (LOI). Prepare 3.0 mm thick strips according to IEC60695-2-12:2021 standard and test their glow wire flammability index (GWIT). Prepare 3.0 mm thick CTI strips according to IEC60112 standard and test their tracking index (CTI). Prepare tensile strips according to ISO 527-2 standard and test their tensile strength. Prepare impact strips according to ISO 179-1 standard and test their notched impact toughness.

[0200] The performance test methods and results for each spline are shown in Table 1.

[0201] Table 1

[0202]

[0203] Application Example 2

[0204] The polyamide composite material is composed of the following components in parts by weight:

[0205] The product contains 61 parts PA66 granules, 9 parts composite flame retardant, 30 parts glass fiber, and 0.5 parts additives (the additives consist of 0.2 parts antioxidant 1010 and 0.3 parts lubricant EBS).

[0206] Among them, the PA66 particles are PA66 material of model N6200 from Guangdong Qide New Material Co., Ltd.

[0207] The composite flame retardant is the modified montmorillonite prepared in Example 1;

[0208] The glass fiber is alkali-free glass fiber roving for thermoplastic plastics, grade 910A, manufactured by China Jushi Co., Ltd.

[0209] The preparation method of polyamide composite material is as follows:

[0210] PA66 granules were dried in an 80℃ vacuum drying oven for 4 hours to remove moisture (to avoid hydrolysis during processing); the composite flame retardant (modified montmorillonite), glass fiber and additives were dried at room temperature for 2 hours.

[0211] Add each component to a high-speed mixer according to the formula ratio, and stir and mix at room temperature (25℃) and 1000r / min for 5 minutes to prepare a mixture.

[0212] The mixture is added to a twin-screw extruder, and the twin-screw extruder parameters are set as follows: screw speed 300 r / min, processing temperature: zone 1 250℃, zone 2 260℃, zone 3 270℃, die head 265℃); after melt blending, it is extruded and granulated to produce a polyamide composite material.

[0213] The polyamide composite material was vacuum dried at 80℃ for 2 hours, and then injection molded into standard test specimens using an injection molding machine. The injection temperature was set to 280℃, the injection pressure to 100MPa, and the holding time to 20s.

[0214] Test specimens were prepared according to the method in Application Example 1, and the performance of each specimen was tested according to the method in Application Example 1. The results are shown in Table 2.

[0215] Table 2

[0216]

[0217] Comparative Application Example 1

[0218] The composition of the polyamide composite materials in Application Example 1 and Application Example 2 is basically the same, except that the composite flame retardant in the polyamide composite material is 15 parts by mass, and the composite flame retardant is composed of the following components by mass:

[0219] Five parts of KH-550 surface-modified montmorillonite prepared in Comparative Example 1 and ten parts of aluminum diethylphosphite (ADP).

[0220] Polyamide composite materials and test specimens were prepared according to the method in Application Example 2, and the properties of each specimen were tested.

[0221] The results are shown in Table 3.

[0222] Table 3

[0223]

[0224] As shown in Table 3, the polyamide composite system of Application Example 1 has poor compatibility, mechanical properties and electrode properties compared to the previous system.

[0225] Comparative Application Example 2

[0226] The polyamide composite material is composed of the following components in parts by weight:

[0227] The product contains 82 parts PA6 granules, 10 parts flame retardant, and 0.5 parts additives (including 0.2 parts antioxidant 1010 and 0.3 parts lubricant EBS).

[0228] Among them, PA6 particles are the same as in application example 1;

[0229] The flame retardant is a composite flame retardant, which is a modified montmorillonite prepared in Comparative Example 2.

[0230] Polyamide composite materials and test specimens were prepared according to the method in Application Example 1, and the properties of each specimen were tested.

[0231] The results are shown in Table 4.

[0232] Table 4

[0233]

[0234] As shown in Table 4, the modified montmorillonite with cerium phosphate intercalation used as a flame retardant in the polyamide composite material of Application Example 2 can only achieve a vertical burning rating of V-1, which cannot meet the requirements of UL94 V-0. Moreover, the LOI is only 23.5%, and the CTI is 530V (with slight traces). Compared with Application Example 1, there is a significant problem of electrical performance degradation.

[0235] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0236] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A method for preparing modified montmorillonite, characterized in that, Includes the following steps: A first modified montmorillonite intermediate was prepared by reacting γ-aminopropyltriethoxysilane with montmorillonite in a first reaction. The cerium salt is mixed with the first modified montmorillonite intermediate in the presence of the first solvent to carry out a second reaction, thereby preparing the second modified montmorillonite intermediate. Phosphorous acid and a second modified montmorillonite intermediate are mixed in the presence of a second solvent to carry out a third reaction, thereby preparing the modified montmorillonite.

2. The method for preparing modified montmorillonite according to claim 1, characterized in that, It meets at least one of the following characteristics: (1) The mass ratio of the γ-aminopropyltriethoxysilane to the montmorillonite is (2-3):(8-10); (2) The conditions for the first reaction include: pH 5.0-5.5; (3) The conditions for the first reaction include: temperature of 60℃-80℃; time of 5h-6h.

3. The method for preparing modified montmorillonite according to claim 1 or 2, characterized in that, The specific steps of the first reaction between γ-aminopropyltriethoxysilane and montmorillonite include: After hydrolyzing γ-aminopropyltriethoxysilane, it is mixed with an ethanol-water solution of montmorillonite to carry out the first reaction.

4. The method for preparing modified montmorillonite according to claim 3, characterized in that, It meets at least one of the following characteristics: (1) In the ethanol-water solution of the montmorillonite, the volume ratio of ethanol to water is (1-2):(1-2). (2) The specific steps for hydrolyzing γ-aminopropyltriethoxysilane include: γ-aminopropyltriethoxysilane was dissolved in anhydrous ethanol, water was added, and the mixture was stirred at 20℃-30℃ for 10 min-15 min to carry out hydrolysis. Optionally, the volume ratio of the anhydrous ethanol to water is (90-100):(3-5); Optionally, the hydrolysis conditions include a mass-to-volume ratio of γ-aminopropyltriethoxysilane to anhydrous ethanol of (0.2 g - 0.4 g): 1 mL.

5. The method for preparing modified montmorillonite according to claim 1, characterized in that, It meets at least one of the following characteristics: (1) The cerium salt includes CeCl3; (2) The ratio of the total molar amount of montmorillonite cation exchange in the modified montmorillonite intermediate to the molar amount of cerium ions in the cerium salt is (1-1.5):(1-2). (3) The first solvent includes water; (4) The conditions for the second reaction include: reaction temperature of 30℃-40℃; reaction time of 1h-1.5h.

6. The method for preparing modified montmorillonite according to claim 1 or 5, characterized in that, It meets at least one of the following characteristics: (1) The molar ratio of the cerium salt to the phosphorous acid is (1-1.2):(3-3.5); (2) The second solvent includes water; (3) The conditions for the third reaction include: the reaction temperature is 50℃-60℃; the reaction time is 3h-4h.

7. A modified montmorillonite, characterized in that, Prepared by the method for preparing modified montmorillonite according to any one of claims 1-6.

8. The application of modified montmorillonite prepared by the method of any one of claims 1-6 in polyamide composites.

9. A polyamide composite material, characterized in that, The components include the following parts by mass: 60-92 parts polyamide resin, 8-10 parts flame retardant, and 0.2-0.5 parts additives; Wherein, the flame retardant is modified montmorillonite prepared by the method of preparing modified montmorillonite according to any one of claims 1-6 or modified montmorillonite according to claim 7.

10. The polyamide composite material according to claim 9, characterized in that, It meets at least one of the following characteristics: (1) The polyamide resin includes polycaprolactam and / or polyhexamethylene adipamide; (2) The polyamide composite material further includes a reinforcing agent; Optionally, the reinforcing agent in the polyamide composite material is 30 parts by mass; Optionally, the reinforcing agent comprises glass fiber; Optionally, the glass fiber comprises long glass fibers; (3) The additives include at least one of antioxidants and lubricants; Optionally, the polyamide composite material includes 0.2 parts by weight of an antioxidant; Optionally, the antioxidant includes antioxidant 1010; Optionally, the polyamide composite material includes 0.3 parts by weight of lubricant; Optionally, the lubricant includes vinyl bis-stearamide.

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