Liquid crystal polymer material as well as preparation method and application thereof

Abstract

The invention discloses a liquid crystal polymer material as well as a preparation method and application thereof, and belongs to the technical field of high polymer materials, the liquid crystal polymer material adopts a high-melting-point liquid crystal polymer as a matrix, glass fibers, a talcum powder filler system and a flexibilizer are introduced, and when the liquid crystal polymer material is applied to a battery cell pole packaging material, the processing performance is excellent, and the service life is long. According to the invention, the insulation material has the advantages of no melting phenomenon during processing, high external force bearing degree, low cracking degree and high mechanical strength of a welding line remained in packaging, and can maintain long-term insulation of a pole in a battery cell and an outer layer aluminum shell.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, specifically to a liquid crystal polymer material, its preparation method, and its application. Background Technology

[0002] In new energy batteries, the cell serves as a storage unit and is generally composed of a cover plate, an aluminum shell, and connecting plates. The terminals on the cover plate are connected to the connecting plates by laser welding, and the terminals are covered with a layer of encapsulation material to insulate them from the aluminum shell.

[0003] The packaging material used in existing products is generally polyphenylene sulfide (PPS) composite material. This material is prone to melting during the welding process due to temperature fluctuations caused by power fluctuations. At the same time, after welding, it has low resistance to external forces and is very easy to be damaged by external forces.

[0004] On the other hand, the encapsulation material will inevitably leave weld lines during injection molding. During the electrode welding process, the weld lines are prone to cracking due to the force generated by the thermal expansion of the electrode. If the cracking degree is too high, it may cause the failure of the entire cell. If the weld line does not have sufficient mechanical properties, it will also be difficult to ensure the long-term insulation between the electrode and the aluminum shell in the cell during subsequent use. Summary of the Invention

[0005] Based on the deficiencies of existing technologies, the present invention aims to provide a liquid crystal polymer material. This product uses a high-melting-point liquid crystal polymer (LCP) as the matrix, and introduces a glass fiber, talc filler system and toughening agent. When applied to battery cell terminal packaging materials, it has excellent processing performance, does not melt during processing, has a high degree of external force resistance, low cracking degree of the weld lines left in the packaging, high mechanical strength, and can maintain the long-term insulation between the terminal and the outer aluminum shell in the battery cell.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A liquid crystal polymer material comprising the following components in parts by weight:

[0008] 100 parts liquid crystal polymer, 20-50 parts inorganic filler, and 1-20 parts toughening agent;

[0009] The melting point (Tm) of the liquid crystal polymer is 320–380°C;

[0010] The toughening agent is a binary and / or terpolymer containing ethylene methacrylate-glycidyl ester segments;

[0011] The inorganic filler includes glass fiber and talc;

[0012] The liquid crystal polymer material satisfies the following conditions:

[0013] (m1 / m2)*D=550~1050;

[0014] Where m1 is the weight of glass fiber, m2 is the weight of talc, and Dμm is the average length of glass fiber retained.

[0015] Liquid crystal polymers are high-molecular-weight compounds that can exist as a liquid crystal phase under specific conditions. They have higher melting points and ordered orientation, resulting in higher stress uniformity and better processability compared to other plastic materials. They can be processed and welded at higher temperatures without melting. When liquid crystal polymers are used as encapsulation materials for the terminals of new energy battery cells, in addition to requiring sufficient external force resistance to prevent breakage or damage due to terminal expansion or external forces, the strength and toughness of the weld line after welding must also be considered. Otherwise, the required standards cannot be met during subsequent use. Therefore, in this application, a liquid crystal polymer with a high melting point is selected as the main material to avoid melting caused by power fluctuations during welding. Furthermore, based on the current properties of liquid crystal polymers, if the melting point is too high, exceeding 380°C, the mechanical properties of the material will significantly decrease, making it impossible to achieve ideal performance when used in the product described in this invention. Therefore, the temperature range of 320–380°C must be maintained. On the other hand, glass fiber is introduced as… The main purpose of using fillers is to improve the rigidity and strength of the weld line and the ability to withstand conventional external forces. However, the toughness of the weld line will be relatively reduced. Therefore, it is necessary to compound talc powder of a specific size so that the product can balance the rigidity and toughness of the weld line. However, in the liquid crystal polymer matrix, the reaction force and creep of talc powder and glass fiber are different under different temperature and pressure environments. During electrode welding, the product will be subjected to slow and low-level expansion force of the electrode at a higher temperature environment. At this time, the creep tendency of talc powder is stronger, and the retention length of glass fiber will also affect its force and creep tendency. On the other hand, the force that the product is subjected to at room temperature is instantaneous and high-level external force. At this time, the reaction force of glass fiber accounts for a higher proportion. The performance under the two conditions is not necessarily related. To ensure the product balances weldability and resistance to external forces under normal conditions, the inventors established a relationship based on the mass ratio of talc and glass fiber and the average retained length of glass fiber. Simultaneously, a specific type of binary and / or terpolymer of ethylene-glycidyl methacrylate segments was used as a toughening agent. With the action of this toughening agent and the specific gradation of the two fillers, the product maintains sufficient strength under high or low temperature, slow low pressure, or instantaneous external force. The degree of cracking after welding is minimal, and the product has a high resistance to external forces. If the ratio of talc to glass fiber is unbalanced, or if the glass fiber size is improperly selected, leading to an imbalance in the relationship, not only will the weld line strength and toughness be affected, but the product's weldability and resistance to external forces will also be compromised. Furthermore, different toughening agents have varying effects on liquid crystal polymers; if other types of toughening agents are selected, the product may not achieve the desired overall performance.

[0016] Preferably, the liquid crystal polymer material comprises the following components in parts by weight:

[0017] 100 parts liquid crystal polymer, 18-35 parts glass fiber, 3-20 parts talc, and 1-20 parts toughening agent;

[0018] More preferably, in the liquid crystal polymer material, the mass content of the liquid crystal polymer is ≥60wt%.

[0019] The method for testing the average retention length of glass fibers in the liquid crystal polymer material described in this invention is as follows:

[0020] First, the liquid crystal polymer material particles or products are fired at 650℃ for 30 minutes to remove the resin matrix and retain the inorganic matter. Glass fibers are then screened using ultrasonic treatment. The glass fibers are then evenly dispersed in water. The average length of the retained glass fibers is observed, tested, and confirmed using a two-dimensional microscope. 200 glass fibers are screened, and the average value is calculated.

[0021] It should be noted that the average length of glass fiber retention in the liquid crystal polymer material described in this invention refers to the average length of glass fiber retention in the product after the liquid crystal polymer material is melt-extruded and granulated.

[0022] Preferably, the liquid crystal polymer includes at least one of aromatic thermoplastic polyester and aromatic lyotropic polyester;

[0023] More preferably, the liquid crystal polymer includes, but is not limited to, at least one of the following structural units:

[0024]

[0025] Preferably, the melting point of the liquid crystal polymer is a range of one or any two of 320°C, 330°C, 340°C, 350°C, 360°C, 370°C, and 380°C.

[0026] The melting point of the liquid crystal polymer was determined directly by DSC calorimetry using an SR-1 tester with a heating rate of 10℃ / min and a maximum test temperature of 500℃.

[0027] Preferably, the melt viscosity of the liquid crystal polymer at a melting point of +20°C and a shear rate of 1000 / s is 10 to 150 Pa / s; more preferably, it is a value within the range of one or any two of 10 Pa / s, 30 Pa / s, 50 Pa / s, 80 Pa / s, 100 Pa / s, 120 Pa / s, 130 Pa / s, and 150 Pa / s.

[0028] More preferably, the melt viscosity is directly measured using a capillary rheometer.

[0029] Preferably, the average length of the retained glass fiber is 50–400 μm.

[0030] Preferably, the average length of the retained glass fiber is within the range of one or any two of the following: 50μm, 60μm, 70μm, 80μm, 90μm, 100μm, 150μm, 200μm, 250μm, 300μm, 350μm, and 400μm.

[0031] Preferably, the average length of the glass fiber is 1 to 10 mm, and the average diameter of the glass fiber is 8 to 12 μm.

[0032] It should be noted that the average length of the glass fiber in the liquid crystal polymer material described in this invention refers to the initial average length of the glass fiber before the liquid crystal polymer material is melt-extruded and granulated.

[0033] The test method for the average length and average diameter of the glass fiber is as follows: the glass fiber is uniformly dispersed in water by ultrasonication and then observed, tested and confirmed by a two-dimensional microscope. The number of glass fibers selected is 200, and the average value is calculated.

[0034] Preferably, the average particle size of the talc powder is 2.5 to 7 μm.

[0035] More preferably, the average particle size of the talc powder is 4 to 5 μm.

[0036] The method for testing the average particle size of the talc powder is as follows: the talc powder is placed in water and ultrasonically dispersed, and then the average particle size of the talc powder is observed, tested and confirmed using a two-dimensional microscope. The number of talc powder particles screened is 200, and the average value is calculated.

[0037] As mentioned above, when talc powder and glass fiber are compounded in a liquid crystal polymer matrix, the creep activity is higher during the welding process. The creep tendency naturally varies with different sizes. The size of talc powder is also related to its dispersibility and compatibility in the product. After screening, the product prepared with talc powder in the above ratio has better overall performance.

[0038] Preferably, the average particle size of the talc is 2–6 μm.

[0039] The method for testing the retained average particle size of talc in the liquid crystal polymer material of the present invention is as follows:

[0040] First, the liquid crystal polymer material particles or products are fired at 650℃ for 30 minutes to remove the resin matrix and retain the inorganic matter. The talc powder is then screened by ultrasonic treatment. The talc powder is then evenly dispersed in water. The average particle size of the retained talc powder is observed, tested and confirmed using a two-dimensional microscope. The number of talc powder particles screened is 200, and the average value is calculated.

[0041] It should be noted that the average retained particle size of talc in the liquid crystal polymer material described in this invention refers to the average retained particle size of talc in the product after the liquid crystal polymer material is melt-extruded and granulated.

[0042] Preferably, the toughening agent contains ≥6 wt% glycidyl methacrylate.

[0043] Preferably, the toughening agent is at least one of ethylene-glycidyl methacrylate binary copolymer, ethylene-glycidyl methacrylate-methyl methacrylate terpolymer, ethylene-glycidyl methacrylate-butyl acrylate terpolymer, and ethylene-glycidyl methacrylate-vinyl acetate terpolymer.

[0044] Preferably, the toughening agent is an ethylene-glycidyl methacrylate copolymer;

[0045] More preferably, the glycidyl methacrylate content in the ethylene-glycidyl methacrylate binary copolymer is ≥10wt%.

[0046] The glycidyl methacrylate content in the toughening agent can be directly quantitatively determined by infrared spectroscopy or by titration: M g of the sample is heated to dissolve under reflux in an organic solvent, V1 (L) of trichloroacetic acid-xylene standard solution (concentration C1, mol / L) is added and refluxed, followed by the addition of several drops of phenolphthalein reagent. After turning on the vortex and confirming that no flocculent matter precipitates out, titration is performed at 75°C using KOH-methanol standard solution (concentration C2, mol / L) until the solution changes color. The volume of KOH-methanol standard solution consumed, V2 (L), is recorded. The content of the GMA segment is determined to be 14.22 × (C2 × V1 - C1 × V2) / M.

[0047] Due to the different types of chain segments, the binary or ternary copolymers of ethylene and glycidyl methacrylate (GMA) graft copolymers have different crosslinking properties and compatibility with liquid crystal polymers. When ethylene-glycidyl methacrylate binary copolymers are selected and their GMA content reaches more than 10wt%, the weldability and external force resistance of the product are improved more significantly, and the overall performance of the product is better.

[0048] More preferably, the liquid crystal polymer material further comprises 0.01 to 1 part of processing aids, wherein the processing aids include at least one of antioxidants and lubricants.

[0049] Based on the needs of actual products, those skilled in the art may appropriately introduce some components commonly used in LCP products without affecting product performance, such as antioxidants to improve the product's conventional oxidation resistance, lubricants to improve the product's processing performance, etc.

[0050] More preferably, the antioxidant is at least one of hindered phenolic antioxidants and phosphite antioxidants, and the lubricant is at least one of organosilicon lubricants and stearic acid lubricants.

[0051] Another object of the present invention is to provide a method for preparing the liquid crystal polymer material, comprising the following steps:

[0052] The components are added to a screw extruder for melt extrusion and granulation to obtain the liquid crystal polymer material.

[0053] Preferably, the heating temperature of the screw extruder is the melting point of the liquid crystal polymer + 10°C, and the screw speed is 200-400 rpm.

[0054] The preparation method of the liquid crystal polymer material described in this invention is simple, requires little equipment, and can be industrialized for large-scale production.

[0055] Preferably, the screw extruder is a twin-screw extruder.

[0056] The average retained length of the glass fibers in the liquid crystal polymer material described in this invention can be adjusted by selecting the initial length of the glass fibers, the location of the glass fibers (the position of the side feed inlet), the screw speed of the twin-screw extruder, and the length-to-diameter ratio of the screw. Methods known in the art for controlling the average retained length of glass fibers (such as controlling the initial average length of the glass fibers, changing the location of the glass fibers, controlling the screw speed of the twin-screw extruder, or controlling the length-to-diameter ratio of the screw) can all be applied to this invention. In this invention, by keeping the screw speed and length-to-diameter ratio of the twin-screw extruder constant, the location of the glass fibers can be changed to alter the retained length and its distribution. Specifically, the twin-screw extruder of the present invention has four side feed ports, with the first, second, third, and fourth side feed ports located sequentially away from the motor end and close to the extruder outlet. Since the glass fiber breaks and shortens in length when sheared by the screw in the extruder, glass fibers with different average retention lengths can be obtained by adding them from side feed ports at different positions. If the glass fiber is added from the side feed port close to the motor end (e.g., the first side feed port), the glass fiber is sheared for a longer time in the extruder, resulting in a shorter average retention length. If the glass fiber is added from the side feed port away from the motor end (e.g., the fourth side feed port), the glass fiber is sheared for a shorter time in the extruder, resulting in a longer average retention length.

[0057] Another object of the present invention is to provide the application of the liquid crystal polymer material in the preparation of battery terminal encapsulation materials.

[0058] Preferably, the battery terminal encapsulation material includes a terminal ring sealant or a terminal elliptical ring sealant.

[0059] Another object of the present invention is to provide a battery cell comprising the aforementioned terminal ring sealant, or a battery terminal encapsulation material comprising the liquid crystal polymer of the present invention.

[0060] When the liquid crystal polymer material described in this invention is used as an electrode encapsulation material, it can withstand the temperature surge caused by power fluctuations during electrode welding without melting. Furthermore, it does not exhibit significant cracking or even penetration due to the thermal expansion of the metal electrode during welding. It has excellent processing performance, and the weld line remaining after welding possesses ideal strength and toughness, ensuring long-term stability and preventing damage, thus avoiding contact between the electrode and the battery cell casing. As an encapsulation material covering the electrode, it has high resistance to external forces, withstanding destructive thrusts exceeding 1700N. Its overall processing and performance are excellent, making it a complete replacement for existing products such as the PPS system.

[0061] The beneficial effects of this invention are that it provides a liquid crystal polymer material. This product uses a high-melting-point liquid crystal polymer (LCP) as the matrix and introduces a glass fiber, talc filler system and toughening agent. When applied to the battery cell terminal packaging material, it has excellent processing performance, does not melt during processing, has a high degree of external force resistance, low cracking degree of the weld lines left in the packaging, high mechanical strength, and can maintain the long-term insulation between the terminal and the outer aluminum shell in the battery cell. Detailed Implementation

[0062] To better illustrate the purpose, technical solution, and advantages of this invention, the invention will be further described below with reference to specific embodiments and comparative examples. The purpose of this description is to provide a detailed understanding of the invention, not to limit its scope. All other embodiments obtained by those skilled in the art without inventive effort are within the protection scope of this invention. Unless otherwise specified, the experimental reagents and instruments involved in the implementation of this invention are commonly used reagents and instruments.

[0063] Examples 1-13

[0064] An embodiment of the liquid crystal polymer material, its preparation method, and its application described in this invention is shown in Table 1.

[0065] The method for preparing the liquid crystal polymer material includes the following steps:

[0066] The components are mixed evenly, and then melt-extruded and granulated in a screw extruder to obtain the liquid crystal polymer material.

[0067] During melt extrusion, the temperature zone of the twin-screw extruder is set to the melting point of the liquid crystal polymer used +10°C, the screw speed is 300 rpm, and the screw length-to-diameter ratio is 48:1.

[0068] In Examples 2, 4, 16 and 8, the glass fibers were fed into the fourth feed port of the screw extruder; in Examples 14 and 10, the glass fibers were fed into the first feed port of the screw extruder; in Examples 15, 17 and 7, the glass fibers were fed into the first feed port of the screw extruder; and in the other examples and comparative examples, the glass fibers were fed into the second feed port of the screw extruder.

[0069] Comparative Examples 1-8

[0070] The only difference between each comparative example and the embodiment is the type and ratio of components, as shown in Table 2.

[0071] In the components described in each embodiment and comparative example,

[0072] The liquid crystal polymer 1 is Vicryst R85 produced by Zhuhai Wantong, with a melting point of 330±10℃.

[0073] The liquid crystal polymer 2 is Vicryst R8 produced by Zhuhai Wantong, with a melting point of 350±10℃.

[0074] The liquid crystal polymer 3 is Vicryst R82 produced by Zhuhai Wantong, with a melting point of 370±10℃.

[0075] The liquid crystal polymer 4 is Vicryst R80 produced by Zhuhai Wantong, with a melting point of 280±10℃.

[0076] The liquid crystal polymer 5 is Vicryst R8ST produced by Zhuhai Wantong, with a melting point of 420±10℃.

[0077] The toughening agent 1 is BF-E, an ethylene-glycidyl methacrylate copolymer produced by Sumitomo Chemicals of Japan, with a glycidyl methacrylate content of 12 wt%.

[0078] The toughening agent 2 is BF-2C, an ethylene-glycidyl methacrylate copolymer produced by Sumitomo Chemicals of Japan, with a glycidyl methacrylate content of 6 wt%.

[0079] The toughening agent 3 is BF-2B produced by Sumitomo Chemicals of Japan, an ethylene-glycidyl methacrylate-vinyl acetate terpolymer, with a glycidyl methacrylate content of 12wt%.

[0080] The toughening agent 4 is BF-7M produced by Sumitomo Chemicals of Japan, an ethylene-glycidyl methacrylate-methyl methacrylate terpolymer, with a glycidyl methacrylate content of 6 wt%.

[0081] The toughening agent 5 is Elvaloy AC 1820 produced by DuPont Chemicals, an ethylene-methyl acrylate copolymer with a methyl acrylate content of 20 wt%.

[0082] The toughening agent 6 is Surlyn 9910 produced by DuPont Chemicals, a zinc ion polymer based on ethylene-methacrylic acid;

[0083] The glass fiber 1 is Owens Corning 923 product, with an initial average length of 3 mm and a diameter of 10 μm.

[0084] The glass fiber 2 is HMG436S-10-4 produced by Taishan Glass Fiber, with an initial average length of 4mm and a diameter of 10μm.

[0085] The talc powder 1 is AH3000 produced by Liaoning Aihai Talc, and its average particle size is 2.5μm after screening;

[0086] The talc powder 2 is AH 51215 produced by Liaoning Aihai Talc Co., Ltd., and its average particle size is 4μm after screening;

[0087] The talc powder 3 is from the same source as talc powder 2, and its average particle size is 4.5 μm after screening;

[0088] The talc powder 4 is AH 51220 produced by Liaoning Aihai Talc Co., Ltd., and its average particle size is 6μm after screening;

[0089] The mica powder is SM-515 produced by Green Mining Co., Ltd., with an average particle size of 5μm.

[0090] Unless otherwise specified, all components and raw materials used in the embodiments and comparative examples of this invention are commercially available, and the same type of components and raw materials are used in each parallel experiment.

[0091] In each embodiment and comparative example, the liquid crystal polymer material was calcined at 650°C for 30 minutes to remove the resin matrix and retain the inorganic matter. Glass fiber and talc particles were screened using ultrasonic treatment. The glass fiber and talc particles were uniformly dispersed in water. The average length of the retained glass fiber was observed and confirmed using a two-dimensional microscope. 200 glass fibers were screened, and the average value was calculated. Simultaneously, the average particle size of the retained talc was observed and confirmed using a two-dimensional microscope. 200 talc particles were screened, and the average value was calculated.

[0092] In Table 1, X = (m1 / m2) * D;

[0093] Table 1

[0094]

[0095]

[0096] Table 2

[0097]

[0098] To verify the performance of the liquid crystal polymer material described in this invention, the products prepared in each embodiment and comparative example were subjected to the following performance tests, the specific steps of which are as follows:

[0099] (1) Tensile strength and elongation at break of the weld line: First, the product is injection molded into a 115*10*0.75mm sample using a mold with glue at both ends. The sample has a weld line. Then, the tensile strength and elongation at break of the weld line are tested according to ISO 527-2-2012. The test temperature is 23℃ and the test speed is 2mm / min.

[0100] (2) Welding performance test: The product was injection molded into a ring-shaped encapsulation material with an inner diameter of 13mm, an outer diameter of 17mm, and a thickness of 0.5mm using a single-screw injection molding machine. Then, 100 negative electrode posts of the battery cell were assembled using commercially available materials. Subsequently, the product was welded using commercially available connecting pieces with a 3300W power laser welding machine. The melting phenomenon of the encapsulation material was observed during the welding process. Under a two-dimensional microscope, the cracking situation and cracking area ratio of the product after welding were statistically analyzed using measurement-observation software. The product was then rated according to the following standards.

[0101] Grade A: No cracks in the pole;

[0102] Grade B: The area of ​​the pole crack is ≤20%, with no through-crack phenomenon, which meets the product usage requirements;

[0103] Grade C: The area of ​​the pole crack is greater than 20%, with no through-crack phenomenon, and can only meet the requirements of specific products;

[0104] Grade D: The pole is pierced and cannot be used.

[0105] One hundred parallel samples for each product are statistically analyzed at the lowest level for each individual sample.

[0106] (3) Test of the destructive thrust of the pole: Select 10 products rated B in each product in step (2) (if insufficient, make new samples to make up the difference), fix them, and then place them on a specific fixture. The metal pole is held in place by the fixed top rod. Use a thrust gauge to destroy the outer plastic and record the maximum force when the plastic is destroyed, which is the magnitude of the pole destruction thrust. Record the maximum thrust when the packaging material is destroyed.

[0107] The test results are shown in Tables 3 and 4.

[0108] Table 3

[0109]

[0110] Table 4

[0111]

[0112] As can be seen from Tables 3 and 4, the liquid crystal polymer material described in this invention has ideal comprehensive performance. The tensile strength of the weld line can reach 35 MPa or above, and the elongation at break can reach 0.9% or above. No melting phenomenon occurred during the welding process, and the cracking level after welding can be maintained at A to B level, which fully meets the usage standards of battery cell terminals. Furthermore, as an encapsulation material, it has high resistance to external forces and can withstand external forces of at least 1750 N. This is mainly due to the combination of a liquid crystal polymer matrix with a specific melting point and a specific type of binary and / or ternary copolymer toughening agent, while optimizing and controlling the mass / length relationship of the glass fiber and talc used.

[0113] As can be seen from Examples 1, 6-7 and Comparative Examples 1-2, liquid crystal polymers with different melting points result in different degrees of crosslinking and compatibility with inorganic materials and toughening agents after product preparation. Liquid crystal polymers with low melting points will melt during welding, resulting in poor processing performance and poor welding performance. On the other hand, products prepared from liquid crystal polymers with excessively high melting points also have unsatisfactory weld line mechanical properties and poor processing performance. Therefore, it is necessary to specifically select the melting point of the liquid crystal polymer.

[0114] As can be seen from Examples 1, 8-10, and Comparative Examples 4-5, different types of toughening agents have different modification effects on the liquid crystal polymer material system described in this invention. If a toughening agent other than ethylene-glycidyl methacrylate system is selected, the product cannot achieve the ideal toughening effect, cannot maintain the balance between weld line tensile strength and elongation at break, and may lead to a decrease in the product's ability to withstand external forces. Among binary and / or ternary polymers containing ethylene-glycidyl methacrylate segments, ethylene-glycidyl methacrylate binary copolymers, especially those with a glycidyl methacrylate content greater than 10 wt%, have the best effect.

[0115] As can be seen from Examples 1, 3-4 and Comparative Example 3, the amount of toughening agent added is not necessarily better the more it is added. With the addition of toughening agent, the tensile strength of the weld line of the product gradually decreases, and the external force bearing capacity also decreases. Although the cracking grade of the product is improved, if too much is introduced, the stress stability during the welding process will drop sharply, and the cracking grade of the product will drop again. Therefore, it is necessary to limit the amount added to a specific range.

[0116] As can be seen from Examples 1 and 11-13, in addition to the length of the glass fiber, the size of the talc powder also affects its tightness and dispersion when riveted with glass fiber composites, which in turn leads to different product performance. After optimization, talc powder with an average particle size of 4-5 μm has better performance.

[0117] As can be seen from Examples 1, 2, 5, and 14-17, the ratio of the two inorganic fillers, the length of the glass fiber, and the amount of toughening agent added in the product change in real time, and all kinds of properties of the product will change accordingly. Although the properties are related, they are not actually the same. For example, the weld line performance and cracking grade of the products in Examples 1 and 17 are similar, but the maximum thrust of the pole breaking is significantly different. The weld line elongation at break in Example 5 is higher than that in Examples 1 and 2, but there is no similar pattern in the comparison of the maximum thrust of the pole breaking among the three. Based on this, if the ratio of toughening agent is fixed, adjusting (m1 / m2)*D will cause the various properties of the product to change. The main reason is that glass fiber and talc, two fillers with different morphologies, have different degrees of bonding with the resin matrix, different degrees of dispersion, and different creep properties during processing. If the formulation is not appropriate, as shown in Comparative Examples 7-10, the product cannot take into account the weld line performance, welding performance, and external force resistance. Only when (m1 / m2)*D is in the range of 550-1050 can the product achieve the expected effect. As can be seen from Comparative Example 6, when the filler system is replaced from glass fiber + talc powder to glass fiber + mica powder, even if the product meets the requirement that (m1 / m2)*D is within 550~1050, the product cannot meet the ideal riveting effect and dispersion effect. The maximum destructive thrust of the product's pole is only 1500N, which is not good. Other properties are also weakened compared to the product of Example 2 with the same formula.

[0118] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A liquid crystal polymer material, comprising the following components in parts by weight: 100 parts liquid crystal polymer, 20-50 parts inorganic filler, and 1-20 parts toughening agent; The melting point of the liquid crystal polymer is 320–380°C; The toughening agent is a binary and / or terpolymer containing ethylene-glycidyl methacrylate segments; The inorganic filler includes glass fiber and talc; The liquid crystal polymer material satisfies the following conditions: (m1 / m2)*D=550~1050; Where m1 is the weight of glass fiber, m2 is the weight of talc, and Dμm is the average retention length of glass fiber.

2. The liquid crystal polymer material as described in claim 1, characterized in that, The glass fiber has an average length of 1–10 mm and an average diameter of 8–12 μm; the talc powder has an average particle size of 2.5–7 μm.

3. The liquid crystal polymer material as described in claim 1, characterized in that, The average length of the glass fiber retained in the liquid crystal polymer material is 50–400 μm, and the average particle size of the talc is 2–6 μm.

4. The liquid crystal polymer material as described in claim 1, characterized in that, The toughening agent contains ≥6 wt% glycidyl methacrylate; the toughening agent is at least one of ethylene-glycidyl methacrylate binary copolymer, ethylene-glycidyl methacrylate-methyl methacrylate terpolymer, ethylene-glycidyl methacrylate-butyl acrylate terpolymer, and ethylene-glycidyl methacrylate-vinyl acetate terpolymer.

5. The liquid crystal polymer material as described in claim 4, characterized in that, The toughening agent is an ethylene-glycidyl methacrylate binary copolymer; preferably, the mass content of glycidyl methacrylate in the ethylene-glycidyl methacrylate binary copolymer is ≥10wt%.

6. The method for preparing the liquid crystal polymer material according to any one of claims 1 to 5, characterized in that, Includes the following steps: The components are added to a screw extruder for melt extrusion and granulation to obtain the liquid crystal polymer material.

7. The use of the liquid crystal polymer material as described in any one of claims 1 to 5 in the preparation of battery terminal encapsulation materials.

8. The application as described in claim 7, characterized in that, The battery terminal encapsulation material includes a terminal ring or an elliptical terminal ring sealant.

9. A type of electrode ring sealant, characterized in that, Includes the liquid crystal polymer material according to any one of claims 1 to 5.

10. A battery cell, characterized in that, It includes the electrode ring sealant as described in claim 9, or the battery electrode encapsulation material including the liquid crystal polymer material as described in any one of claims 1 to 5.

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