Talc powder composite filler, preparation method and application thereof

Abstract

This invention belongs to the field of composite filler technology. This invention provides a talc composite filler, its preparation method, and its application. The method comprises the following steps: S1, pretreating talc powder and wollastonite fiber separately using a silane coupling agent to obtain modified talc powder and modified wollastonite fiber; S2, mixing 5 parts by weight of the modified talc powder, 15 parts by weight of the modified wollastonite fiber, and 0.8-0.9 parts by weight of polyimide microsphere-nano silica dopant to obtain a mixture; S3, adding 1-1.2 parts by weight of aluminum borate whiskers to the mixture obtained in S2, mixing thoroughly, and obtaining the talc composite filler. This invention, by limiting the amount of wollastonite fiber added, ensures excellent tensile strength of the prepared polypropylene composite material while further improving its flexural strength.

Description

Technical Field

[0001] This invention belongs to the field of composite filler technology, specifically relating to a talc composite filler, its preparation method, and its application. Background Technology

[0002] Talc, a widely used mineral filler, plays a significant role in the modification of polypropylene (PP). It enhances the thermal stability and mechanical strength of PP and facilitates successful molding by regulating and balancing molding shrinkage. Wollastonite, a chain-like metasilicate mineral, often exists as needle-like or fibrous aggregates; even tiny particles retain a fibrous structure. With its unique crystal morphology, excellent dielectric properties, and superior heat resistance, wollastonite is favored not only in ceramic processing but also as a polymer filler. It can reduce production costs and optimize the overall performance of polymer products. High aspect ratio wollastonite is an excellent filler modifier, demonstrating outstanding performance in plastic reinforcement, effectively improving plastic properties and providing strong support for the development of the plastics industry.

[0003] In existing technologies, talc powder and wollastonite fibers are treated with a silane coupling agent to obtain a composite filler, which is then applied to polypropylene to produce composite materials. As the amount of wollastonite fiber increases, the flexural strength of the composite material continuously improves; however, when the amount of wollastonite fiber increases excessively, the tensile strength of the resulting composite material decreases with further increases in wollastonite fiber content. Summary of the Invention

[0004] To address the problems existing in the background art, the present invention provides a talc composite filler, its preparation method and application. By limiting the amount of wollastonite fiber added, the tensile strength of the obtained polypropylene composite material is ensured to be excellent, while its flexural strength is further improved.

[0005] To achieve the above objectives, in a first aspect, the present invention provides a method for preparing talc composite filler, comprising the following steps: S1. Talc powder and wollastonite fiber are pretreated with silane coupling agent to obtain modified talc powder and modified wollastonite fiber. S2. By weight, 5 parts of the modified talc powder, 15 parts of the modified wollastonite fiber and 0.8-0.9 parts of the polyimide microsphere-nano silica dopant are mixed to obtain a mixture; S3. Add 1-1.2 parts of aluminum borate whiskers to the mixture obtained in S2, mix well, and the talc composite filler is obtained.

[0006] Further, in S1, the specific operation of the pretreatment is as follows: talc powder / wollastonite fiber is added to a silane coupling agent alcohol dilution solution, and the amount of silane coupling agent is 0.8-0.9% of the mass of talc powder / wollastonite fiber; after stirring at room temperature, it is placed in a forced-air drying oven and dried to obtain the modified talc powder / modified wollastonite fiber.

[0007] Furthermore, the stirring speed is 220-300 r / min, and the stirring time is 5-8 min.

[0008] Furthermore, the drying temperature is 80±2℃, and the drying time is 2-2.5h.

[0009] Furthermore, in S3, the specific operation of mixing is as follows: stirring and mixing for 12-15 minutes at a rotation speed of 350-400 r / min.

[0010] Furthermore, the preparation method of the polyimide microsphere-nano silica dopant is as follows: A1. Dissolve 0.4 g of 4,4'-diaminodiphenyl ether (ODA) in 2 g of N,N-dimethylformamide (DMF) as the dispersed phase; Two surfactants, 0.96 g of Span85 and 0.24 g of Tween80, were compounded and dispersed in 8 g of liquid paraffin (LP) as a continuous phase. The dispersed phase and the continuous phase were mixed and stirred continuously to obtain a stable and homogeneous reverse emulsion system; then 0.2g of nano silica was added and ultrasonically stirred for 1h to uniformly disperse the nano silica and form a stable reverse non-aqueous emulsion. A2. Weigh 0.444 g of pyromellitic dianhydride (PMDA) according to the molar ratio of 4,4'-diaminodiphenyl ether (ODA): pyromellitic dianhydride (PMDA) 1:1.02, add it in batches to the reverse non-aqueous emulsion obtained in A1, and polymerize for 5 h to obtain PAA emulsion. A pyridine-acetic anhydride mixture was added dropwise to the PAA emulsion to carry out chemical imidization, precipitating polyimide particles. A3. The polyimide particles are washed, centrifuged, and thermally imidized at high temperature to obtain the polyimide microspheres-nano silica dopant.

[0011] Furthermore, in A2, the pyridine-acetic anhydride mixture contains 0.24 g of pyridine and 0.31 g of acetic anhydride.

[0012] In a second aspect, the present invention provides a talc composite filler prepared by the above-described preparation method.

[0013] Thirdly, the present invention provides an application of the talc composite filler prepared by the above-described preparation method in the preparation of polypropylene composite materials.

[0014] Further, 21.5g of the talc composite filler and 100g of polypropylene are uniformly mixed in a high-speed mixer for 5 minutes to obtain a blend; the blend is then extruded and granulated using a twin-screw extruder to obtain the polypropylene composite material.

[0015] This application has the following beneficial effects: This invention introduces polyimide microspheres-nano silica dopants; nano-SiO2 cores construct local rigid nodes, improving the matrix's resistance to bending deformation; SiO2 nanoparticles dispersed in the gaps between the filler network act as rigid support points, filling the voids created by the stacking of talc and wollastonite, forming discontinuous rigidity transmission channels, and enhancing the material's resistance to bending and deflection; the polyimide microspheres cross-link and overlap inorganic fillers, perfecting the rigidity transmission pathway; the polyimide aromatic ring rigid skeleton can form organic-inorganic connecting bridges between talc and wollastonite, allowing bending loads to be efficiently transmitted between fillers, reducing the degree of bending deformation and improving bending strength.

[0016] The polyimide organic shell buffers interfacial stress and improves interfacial compatibility; the outer polymer chains of the polyimide microspheres can form molecular entanglements with the surfaces of polypropylene and silane-modified talc / silica fibers, constructing a flexible transition interface layer. When the material is subjected to tensile force, the interface will not instantly debond, the load is evenly transferred, and tensile strength is guaranteed.

[0017] This invention also incorporates aluminum borate whiskers; the aluminum borate whiskers, as secondary rigid fibers, are interwoven within the wollastonite fiber network to form a multi-level fiber-reinforced skeleton with varying thicknesses. Furthermore, the elastic modulus of the aluminum borate whiskers is higher than that of the wollastonite fibers. When subjected to bending stress, the whiskers and fibers share the bending stress, thereby improving the bending strength.

[0018] Aluminum borate whiskers have a smaller diameter than wollastonite fibers, are uniformly interwoven and dispersed, and do not have large-sized agglomerates. Compared with directly increasing the amount of wollastonite fibers, a small number of whiskers will not generate a large number of crack initiation points. When the material is stretched, external force can induce the whiskers to be pulled out of the polypropylene matrix. The pull-out process consumes a large amount of fracture energy, ensuring that the tensile strength is not reduced.

[0019] 3. Aluminum borate whiskers intertwine and overlap with wollastonite fibers to form a linear and continuous bending-resistant main skeleton, responsible for transmitting bending loads over long distances. Polyimide microspheres and nano-silica dopants are uniformly filled in the micron-level voids formed by the interweaving of aluminum borate whiskers, wollastonite fibers, and talc powder. A large number of nano-rigid SiO2 nodes are distributed in the gaps between the skeleton to fill the voids and eliminate the weak bending areas caused by voids in the network. Finally, a three-dimensional inorganic reinforcement network of continuous fiber skeleton + nano-rigid nodes is formed, which synergistically improves bending strength. Attached Figure Description

[0020] Figure 1 This is a comparative trend chart of the tensile strength and flexural strength test data of polypropylene composite material samples prepared in Examples 1-3 and Comparative Examples 1-4 of the present invention. Detailed Implementation

[0021] The present application will be further described in detail below with reference to the embodiments.

[0022] Unless otherwise specified, the raw materials used in the embodiments and comparative examples of this application are all commercially available.

[0023] Example 1:

[0024] (1) Preparation of polyimide microspheres-nano silica doped materials, the preparation method is as follows: A1. Dissolve 0.4 g of 4,4'-diaminodiphenyl ether (ODA) in 2 g of N,N-dimethylformamide (DMF) as the dispersed phase; Two surfactants, 0.96 g of Span85 and 0.24 g of Tween80, were compounded and dispersed in 8 g of liquid paraffin (LP) as a continuous phase. The dispersed phase and the continuous phase were mixed and stirred continuously to obtain a reverse emulsion; then 0.2g of nano silica was added to the reverse emulsion and ultrasonically stirred for 1h to uniformly disperse the nano silica and form a stable reverse non-aqueous emulsion.

[0025] A2. Weigh 0.444 g of pyromellitic dianhydride (PMDA) according to the molar ratio of 4,4'-diaminodiphenyl ether (ODA): pyromellitic dianhydride (PMDA) 1:1.02, add it to the reverse non-aqueous emulsion obtained in A1 in multiple portions, and polymerize for 5 h to obtain PAA emulsion. A pyridine-acetic anhydride mixture (0.24 g pyridine and 0.31 g acetic anhydride) was added dropwise to the PAA emulsion to perform chemical imidization, precipitating polyimide particles.

[0026] A3. The polyimide particles are washed, centrifuged, and thermally imidized at high temperature to obtain polyimide microspheres-nano silica dopants.

[0027] (2) A method for preparing a talc composite filler, comprising the following steps: S1. Talc powder and wollastonite fiber are pretreated with silane coupling agent to obtain modified talc powder and modified wollastonite fiber.

[0028] Specific operation: Add talc powder / wollastonite fiber to a silane coupling agent alcohol dilution solution, the amount of silane coupling agent is 0.85% of the mass of talc powder / wollastonite fiber; stir at room temperature at a speed of 240 r / min for 6 min; place in a forced-air drying oven and dry at a temperature of 80℃ for 2.2 h to obtain modified talc powder / modified wollastonite fiber.

[0029] S2. By weight, 5 parts of the modified talc powder, 15 parts of the modified wollastonite fiber and 0.85 parts of the polyimide microsphere-nano silica dopant are mixed to obtain a mixture; S3. Add 1.1 parts of aluminum borate whiskers to the mixture obtained in S2 and mix well. Specifically, stir and mix at 360 r / min for 13 min to obtain talc composite filler.

[0030] (3) Prepare polypropylene composite material. The preparation method is as follows: 21.5g of talc composite filler and 100g of polypropylene are uniformly mixed in a high-speed mixer for 5min to obtain a blend; the blend is extruded and granulated by a twin-screw extruder to obtain polypropylene composite material.

[0031] Example 2:

[0032] The difference between this embodiment and Embodiment 1 is that: a method for preparing a talc composite filler includes the following steps: S1. Talc powder and wollastonite fiber are pretreated with silane coupling agent to obtain modified talc powder and modified wollastonite fiber.

[0033] Specific operation: Add talc powder / wollastonite fiber to a silane coupling agent alcohol dilution solution, the amount of silane coupling agent is 0.85% of the mass of talc powder / wollastonite fiber; stir at room temperature at a speed of 240 r / min for 6 min; place in a forced-air drying oven and dry at a temperature of 80℃ for 2.2 h to obtain modified talc powder / modified wollastonite fiber.

[0034] S2. By weight, 5 parts of the modified talc powder, 15 parts of the modified wollastonite fiber and 0.8 parts of the polyimide microsphere-nano silica dopant are mixed to obtain a mixture; S3. Add 1 part of aluminum borate whiskers to the mixture obtained in S2 and mix well. The specific operation is as follows: stir and mix at 350 r / min for 15 min to obtain talc composite filler.

[0035] Example 3:

[0036] The difference between this embodiment and Embodiment 1 is that: a method for preparing a talc composite filler includes the following steps: S1. Talc powder and wollastonite fiber are pretreated with silane coupling agent to obtain modified talc powder and modified wollastonite fiber.

[0037] Specific operation: Add talc powder / wollastonite fiber to a silane coupling agent alcohol dilution solution, the amount of silane coupling agent is 0.85% of the mass of talc powder / wollastonite fiber; stir at room temperature at a speed of 240 r / min for 6 min; place in a forced-air drying oven and dry at a temperature of 80℃ for 2.2 h to obtain modified talc powder / modified wollastonite fiber.

[0038] S2. By weight, 5 parts of the modified talc powder, 15 parts of the modified wollastonite fiber and 0.9 parts of the polyimide microsphere-nano silica dopant are mixed to obtain a mixture; S3. Add 1.2 parts of aluminum borate whiskers to the mixture obtained in S2 and mix well. The specific operation is as follows: stir and mix at 400 r / min for 12 min to obtain talc composite filler.

[0039] Comparative Example 1: The difference between this comparative example and Example 1 is that: no polyimide microspheres-nano silica dopant and aluminum borate whiskers are added; and the amount of modified wollastonite fiber is increased to 18 parts.

[0040] Specifically, a method for preparing a talc composite filler includes the following steps: S1. Talc powder and wollastonite fiber are pretreated with silane coupling agent to obtain modified talc powder and modified wollastonite fiber.

[0041] Specific operation: Add talc powder / wollastonite fiber to a silane coupling agent alcohol dilution solution, the amount of silane coupling agent is 0.85% of the mass of talc powder / wollastonite fiber; stir at room temperature at a speed of 240 r / min for 6 min; place in a forced-air drying oven and dry at a temperature of 80℃ for 2.2 h to obtain modified talc powder / modified wollastonite fiber.

[0042] S2. By weight, 5 parts of the modified talc powder and 18 parts of the modified wollastonite fiber are mixed to obtain a mixture, which is the talc powder composite filler.

[0043] Comparative Example 2: The difference between this comparative example and Example 1 is that no polyimide microspheres-nano silica dopant and aluminum borate whiskers are added.

[0044] Specifically, a method for preparing a talc composite filler includes the following steps: S1. Talc powder and wollastonite fiber are pretreated with silane coupling agent to obtain modified talc powder and modified wollastonite fiber.

[0045] Specific operation: Add talc powder / wollastonite fiber to a silane coupling agent alcohol dilution solution, the amount of silane coupling agent is 0.85% of the mass of talc powder / wollastonite fiber; stir at room temperature at a speed of 240 r / min for 6 min; place in a forced-air drying oven and dry at a temperature of 80℃ for 2.2 h to obtain modified talc powder / modified wollastonite fiber.

[0046] S2. By weight, 5 parts of the modified talc powder and 15 parts of the modified wollastonite fiber are mixed to obtain a mixture, which is the talc powder composite filler.

[0047] Comparative Example 3: The difference between this comparative example and Example 1 is that no polyimide microspheres-nano silica dopant is added.

[0048] Specifically, a method for preparing a talc composite filler includes the following steps: S1. Talc powder and wollastonite fiber are pretreated with silane coupling agent to obtain modified talc powder and modified wollastonite fiber.

[0049] Specific operation: Add talc powder / wollastonite fiber to a silane coupling agent alcohol dilution solution, the amount of silane coupling agent is 0.85% of the mass of talc powder / wollastonite fiber; stir at room temperature at a speed of 240 r / min for 6 min; place in a forced-air drying oven and dry at a temperature of 80℃ for 2.2 h to obtain modified talc powder / modified wollastonite fiber.

[0050] S2. By weight, 5 parts of the modified talc powder and 15 parts of the modified wollastonite fiber are mixed to obtain a mixture; S3. Add 1.1 parts of aluminum borate whiskers to the mixture obtained in S2 and mix well. Specifically, stir and mix at 360 r / min for 13 min to obtain talc composite filler.

[0051] Comparative Example 4: The difference between this comparative example and Example 1 is that aluminum borate whiskers are not added.

[0052] Specifically, a method for preparing a talc composite filler includes the following steps: S1. Talc powder and wollastonite fiber are pretreated with silane coupling agent to obtain modified talc powder and modified wollastonite fiber.

[0053] Specific operation: Add talc powder / wollastonite fiber to a silane coupling agent alcohol dilution solution, the amount of silane coupling agent is 0.85% of the mass of talc powder / wollastonite fiber; stir at room temperature at a speed of 240 r / min for 6 min; place in a forced-air drying oven and dry at a temperature of 80℃ for 2.2 h to obtain modified talc powder / modified wollastonite fiber.

[0054] S2. By weight, 5 parts of the modified talc powder, 15 parts of the modified wollastonite fiber and 0.85 parts of the polyimide microsphere-nano silica dopant are mixed to obtain a mixture, which is the talc powder composite filler.

[0055] Experimental Example: Test Subjects: Polypropylene composite material samples prepared in Examples 1-3 and Comparative Examples 1-4. Test Items and Methods: ① Tensile Strength (MPa) - After injection molding dumbbell-shaped strips were allowed to stand for 24 hours, tensile mechanical properties were tested using a universal tensile testing machine according to GB / T 1040.2-2006. The tensile rate was 50 mm / min, and five strips were taken from each group, and the average value was taken. ② Flexural Strength (MPa) - Tested according to GB / T 9341-2008 Determination of Flexural Properties of Plastics. Test Results: See Table 1.

[0056] Table 1. Experimental Data:

[0057] Results Analysis: Combining the data in Table 1 and... Figure 1 Analysis of Examples 1-3 shows that the tensile strength of the polypropylene composite material samples prepared by the present invention (Examples 1-3) is as high as 25.66 MPa or more, and the flexural strength is as high as 35.42 MPa or more.

[0058] Combining the data in Table 1 and Figure 1 The analysis focused on Example 1 and Comparative Examples 1-4: Specifically, comparing Comparative Example 1 and Comparative Example 2, it can be seen that compared to 18 parts of modified wollastonite fiber in Comparative Example 1, the amount of modified wollastonite fiber in Comparative Example 2 was reduced to 15 parts. As a result, the tensile strength of the polypropylene composite sample was significantly improved, but the flexural strength decreased. This indicates that limiting the amount of modified wollastonite fiber (to avoid excessive use) helps ensure better tensile strength in the polypropylene composite sample, but it also limits the improvement in its flexural strength.

[0059] Specifically, by comparing Comparative Example 2 and Comparative Example 3, it can be seen that, compared with Comparative Example 2, the addition of aluminum borate whiskers in the preparation of talc composite filler in Comparative Example 3 significantly improved the flexural strength of the polypropylene composite sample.

[0060] Specifically, by comparing Comparative Example 2 and Comparative Example 4, it can be seen that, compared with Comparative Example 2, in the preparation of talc composite filler in Comparative Example 4, the addition of polyimide microspheres-nano silica dopants alone resulted in an improvement in the flexural strength of the polypropylene composite sample.

[0061] In comparison with Example 1, it can be seen that in the preparation of talc composite filler, the simultaneous introduction of aluminum borate whiskers and polyimide microspheres-nano silica dopants can produce a synergistic effect, which can synergistically improve the flexural strength of the final polypropylene composite sample.

[0062] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable way without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0063] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A method for preparing a talc composite filler, characterized in that, Includes the following steps: S1. Talc powder and wollastonite fiber are pretreated with silane coupling agent to obtain modified talc powder and modified wollastonite fiber. S2. By weight, 5 parts of the modified talc powder, 15 parts of the modified wollastonite fiber and 0.8-0.9 parts of the polyimide microsphere-nano silica dopant are mixed to obtain a mixture; S3. Add 1-1.2 parts of aluminum borate whiskers to the mixture obtained in S2, mix well, and the talc composite filler is obtained.

2. The method for preparing talc composite filler according to claim 1, characterized in that, In S1, the specific operation of the pretreatment is as follows: talc powder / wollastonite fiber is added to a silane coupling agent alcohol dilution solution, and the amount of silane coupling agent is 0.8-0.9% of the mass of talc powder / wollastonite fiber; after stirring at room temperature, it is dried to obtain the modified talc powder / modified wollastonite fiber.

3. The method for preparing talc composite filler according to claim 2, characterized in that, The stirring speed is 220-300 r / min, and the stirring time is 5-8 min.

4. The method for preparing talc composite filler according to claim 2, characterized in that, The drying temperature is 80±2℃, and the drying time is 2-2.5h.

5. The method for preparing talc composite filler according to claim 1, characterized in that, In S3, the specific operation of mixing is as follows: stirring and mixing for 12-15 minutes at a speed of 350-400 r / min.

6. The method for preparing talc composite filler according to claim 1, characterized in that, The preparation method of the polyimide microsphere-nano silica dopant is as follows: A1. Dissolve 0.4g of 4,4'-diaminodiphenyl ether in 2g of N,N-dimethylformamide as the dispersed phase; disperse 1.2g of surfactant in 8g of liquid paraffin as the continuous phase; mix the dispersed phase and the continuous phase, stir continuously, then add 0.2g of nano silica and stir ultrasonically to obtain a reversed non-aqueous emulsion. A2. Add 0.444 g of pyromellitic dianhydride to the reverse non-aqueous emulsion obtained in A1, polymerize, and then add pyridine-acetic anhydride mixture dropwise to carry out chemical imidization and precipitate polyimide particles. A3. The polyimide particles are washed, centrifuged, and thermally imidized to obtain the polyimide microspheres-nano silica dopant.

7. The method for preparing talc composite filler according to claim 6, characterized in that, In A2, the pyridine-acetic anhydride mixture contains 0.24 g of pyridine and 0.31 g of acetic anhydride.

8. A talc composite filler prepared by the preparation method according to any one of claims 1 to 7.

9. The application of a talc composite filler prepared by the preparation method according to any one of claims 1 to 7, characterized in that, Used in the preparation of polypropylene composite materials.

10. The application according to claim 9, characterized in that, 21.5g of the talc composite filler and 100g of polypropylene were uniformly mixed in a high-speed mixer for 5 minutes to obtain a blend; the blend was then extruded and granulated using a twin-screw extruder to obtain the polypropylene composite material.

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