Composite material and method for manufacturing same, stylus

Abstract

The application relates to the technical field of screen touch materials, in particular to a composite material, a preparation method thereof and a touch pen. The composite material comprises the following components in parts by weight: 100-150 parts of polyurethane, 6-10 parts of modified multi-walled carbon nanotubes, 10-20 parts of modified molybdenum disulfide and 0-3 parts of an antioxidant; wherein the modified multi-walled carbon nanotubes comprise multi-walled carbon nanotubes and polymethyl methacrylate connected with the multi-walled carbon nanotubes, and the multi-walled carbon nanotubes are doped with iodine; the modified molybdenum disulfide comprises molybdenum disulfide and polyamide connected with the molybdenum disulfide. The polyurethane is used as a base material, the modified multi-walled carbon nanotubes and the modified molybdenum disulfide are added to uniformly disperse the multi-walled carbon nanotubes and the molybdenum disulfide in the polyurethane base, so that the composite material has good conductivity and wear resistance, is not prone to deformation and can be well used as a pen head material of a touch pen.

Description

Technical Field

[0001] This application belongs to the field of screen touch material technology, and particularly relates to a composite material and its preparation method, and a stylus. Background Technology

[0002] As a primary tool for human-computer interaction (HCI or HMI), the stylus allows users to write directly on the screen and select documents or draw by tapping the touchscreen.

[0003] To improve user experience, stylus tip materials generally have certain requirements for conductivity, hardness, and wear resistance. Currently, the mainstream stylus tip materials on the market include metal, hard plastic, silicone, and fiber. However, the overall performance of these materials is not ideal and it is difficult to meet the user's writing experience needs. Summary of the Invention

[0004] The purpose of this application is to provide a composite material and its preparation method, as well as a stylus, in order to solve the technical problem that the overall performance of materials currently used for stylus pen tips is poor, which affects the user experience.

[0005] To achieve the above-mentioned objectives, the technical solution adopted in this application is as follows:

[0006] In a first aspect, this application provides a composite material comprising the following components in parts by weight:

[0007]

[0008] Among them, the modified multi-walled carbon nanotubes include multi-walled carbon nanotubes and polymethyl methacrylate connected to the multi-walled carbon nanotubes, and the multi-walled carbon nanotubes are doped with iodine; the modified molybdenum disulfide includes molybdenum disulfide and polyamide connected to molybdenum disulfide.

[0009] In some embodiments, the mass ratio of multi-walled carbon nanotubes to polymethyl methacrylate is 1:(7-15); and / or

[0010] The mass ratio of multi-walled carbon nanotubes to iodine is 1:(0.1-0.3).

[0011] In some embodiments, the polyamide is polymerized from ε-caprolactam and amino groups on the surface of molybdenum disulfide, and the mass ratio of molybdenum disulfide to ε-caprolactam is 1:(6-12).

[0012] In some embodiments, the aspect ratio of the multi-walled carbon nanotubes is 500-1500; and / or

[0013] Molybdenum disulfide includes molybdenum disulfide nanosheets with a particle size of 2000 mesh.

[0014] Secondly, this application provides a method for preparing a composite material, comprising the following steps:

[0015] Provide the components in parts by weight of the composite material provided in the first aspect of this application;

[0016] Polyurethane, modified multi-walled carbon nanotubes, modified molybdenum disulfide, and antioxidants were mixed to obtain a composite material.

[0017] In some embodiments, the preparation steps of modified multi-walled carbon nanotubes include: mixing purified multi-walled carbon nanotubes with methyl methacrylate and an initiator and performing a heated polymerization reaction to obtain multi-walled carbon nanotubes connected with polymethyl methacrylate; mixing the multi-walled carbon nanotubes connected with polymethyl methacrylate and iodine crystals and performing heat treatment to obtain modified multi-walled carbon nanotubes.

[0018] In some embodiments, the purified multi-walled carbon nanotubes comprise multi-walled carbon nanotubes purified using trifluoroacetic acid solvent; and / or,

[0019] The heating polymerization reaction was carried out under trifluoroacetic acid conditions.

[0020] In some embodiments, the preparation steps of modified molybdenum disulfide include: amination treatment of the stripped molybdenum disulfide powder to obtain amino-modified molybdenum disulfide powder; and ring-opening polymerization reaction of the amino-modified molybdenum disulfide powder with ε-caprolactam monomer to obtain modified molybdenum disulfide.

[0021] In some embodiments, the mixing process includes: melt blending at 160-165°C followed by hot pressing at 170-175°C, then cold pressing, and annealing.

[0022] Thirdly, this application provides a stylus, including a pen tip, the material of which includes the composite material provided in the first aspect of this application and / or the composite material prepared by the preparation method provided in the second aspect of this application.

[0023] The first aspect of this application provides a composite material comprising a certain weight proportion of polyurethane, modified multi-walled carbon nanotubes, and modified molybdenum disulfide. The modified multi-walled carbon nanotubes include those linked to polymethyl methacrylate (PMMA) and those doped with iodine. Due to the good compatibility between PMMA and polyurethane, the dispersion of the multi-walled carbon nanotubes in the polyurethane matrix can be improved. Simultaneously, the doped iodine can reduce surface structural defects in the multi-walled carbon nanotubes, thereby improving the overall electrical conductivity of the composite material. The modified molybdenum disulfide includes those linked to polyamide. Due to the good compatibility between polyamide and polyurethane, the dispersion of molybdenum disulfide in the polyurethane matrix is ​​improved, thereby reducing the overall coefficient of friction of the composite material. Therefore, the composite material of this application uses polyurethane as the matrix material. By adding modified multi-walled carbon nanotubes and modified molybdenum disulfide, the PMMA and molybdenum disulfide are uniformly distributed in the polyurethane matrix, resulting in a composite material with excellent electrical conductivity and wear resistance, and it is not easily deformed, making it suitable as a stylus tip material.

[0024] The method for preparing the composite material provided in the second aspect of this application involves mixing the components of the composite material provided in the first aspect of this application in different weight proportions. This preparation method is not only simple, but also yields a composite material with excellent electrical conductivity and wear resistance, and it is not easily deformed, making it well-suited for use as a stylus tip material.

[0025] The stylus provided in the third aspect of this application has a pen tip made of composite material provided in the first aspect of this application and / or composite material prepared by the preparation method provided in the second aspect of this application. Therefore, such a stylus has the advantages of high wear resistance, low deformation and high conductivity when writing on the screen. Because the writing is smooth, it can greatly improve the user experience. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the composite material preparation method provided in the embodiments of this application;

[0028] Figure 2 This is a schematic diagram of the specific process of the composite material preparation method provided in the embodiments of this application. Detailed Implementation

[0029] To make the technical problems, technical solutions, and beneficial effects of this application clearer, the following detailed description is provided in conjunction with embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0030] In this application, the term "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0031] In this application, "at least one" means one or more, and "more than one" means two or more. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of a single item or a plurality of items.

[0032] It should be understood that in the various embodiments of this application, the order of the above processes does not imply the order of execution. Some or all steps may be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0033] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The singular forms “a,” “the,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0034] The weights of the relevant components mentioned in the embodiments of this application can refer not only to the specific content of each component, but also to the proportional relationship between the weights of the components. Therefore, any scaling up or down of the content of the relevant components according to the embodiments of this application is within the scope disclosed in the embodiments of this application. Specifically, the mass described in the embodiments of this application can be a mass unit known in the chemical industry, such as μg, mg, g, or kg.

[0035] The terms "first" and "second" are used for descriptive purposes only, to distinguish objects, such as substances, from one another, and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. For example, without departing from the scope of the embodiments of this application, "first XX" may also be referred to as "second XX," and similarly, "second XX" may also be referred to as "first XX." Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of that feature.

[0036] With the widespread use of styluses, people have increasingly higher requirements for stylus tip materials. Currently, the mainstream stylus tip materials on the market include metal, hard plastic, silicone, and fiber. Generally, metal or plastic tips, which are harder, have high wear resistance, but produce loud writing noise, affecting the user's writing experience. Silicone tips are quieter, but they are prone to significant deformation during writing. Fiber tips offer low writing resistance, but after a period of use, they wear out quickly, significantly impacting the user's writing experience. Existing tip materials struggle to meet users' writing experience needs in all aspects.

[0037] Given that existing stylus tip materials either exhibit large deformation, poor conductivity, or high writing resistance, resulting in unsatisfactory overall performance, this application proposes a composite material that combines high wear resistance, low deformation, high conductivity, and smooth writing when used as a stylus tip material. The specific solution is as follows.

[0038] In a first aspect, embodiments of this application provide a composite material comprising the following components in parts by weight:

[0039]

[0040] Among them, the modified multi-walled carbon nanotubes include multi-walled carbon nanotubes and polymethyl methacrylate connected to the multi-walled carbon nanotubes, and the multi-walled carbon nanotubes are doped with iodine; the modified molybdenum disulfide includes molybdenum disulfide and polyamide connected to molybdenum disulfide.

[0041] Polyurethane, as the matrix material of composite materials, has excellent wear resistance and a wide range of adjustable hardness. It is less likely to damage the screen when writing on it, and by adjusting the hardness, it is less likely to cause large deformation during writing, resulting in a long service life.

[0042] Multi-walled carbon nanotubes (MWCNTs) possess excellent electrical conductivity and self-lubricating properties. The addition of MMCNTs can improve the conductivity of composite materials. However, pure MMCNTs exhibit poor dispersion in polyurethane matrices and are prone to aggregation. Therefore, this application uses modified MMCNTs, which are MMCNTs grafted with polymethyl methacrylate (PMMA) and simultaneously doped with iodine. Based on the good compatibility between PMMA and polyurethane, the dispersion of MMCNTs in the polyurethane matrix can be improved, forming conductive pathways and providing good conductivity to the composite material. Simultaneously, the iodine doping reduces surface structural defects in the MMCNTs. Therefore, such modified MMCNTs can reduce the percolation value of the composite material's conductivity with a relatively small addition amount, while simultaneously improving the composite material's conductivity.

[0043] Molybdenum disulfide (MoS2) possesses excellent anisotropy and a low coefficient of friction, making it a good inorganic lubricant. However, when used as an additive in polyurethane matrices, it is prone to agglomeration. Therefore, this application uses modified molybdenum disulfide, which is molybdenum disulfide linked to polyamide. Based on the good compatibility between polyamide and polyurethane, this improves the dispersibility of molybdenum disulfide in the polyurethane matrix, thereby reducing the overall coefficient of friction of the composite material, decreasing writing damping, and enhancing writing smoothness.

[0044] Therefore, the composite material of this application uses polyurethane as the matrix material. By adding modified multi-walled carbon nanotubes and modified molybdenum disulfide, the polyurethane matrix is ​​made to have a uniform fraction of multi-walled carbon nanotubes and molybdenum disulfide, thereby making the composite material have good electrical conductivity and wear resistance, and it is not easily deformed, so it can be well used as a pen tip material for styluses.

[0045] In one embodiment, the composite material comprises: 100-150 parts of polyurethane, 6-10 parts of modified multi-walled carbon nanotubes, 10-20 parts of modified molybdenum disulfide, and 0-3 parts of antioxidant; wherein, the polyurethane can be 100 parts, 110 parts, 120 parts, 125 parts, 130 parts, 140 parts, 145 parts, 150 parts, etc., the modified multi-walled carbon nanotubes can be 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, etc., the modified molybdenum disulfide can be 10 parts, 12 parts, 14 parts, 15 parts, 16 parts, 18 parts, 20 parts, etc., and the antioxidant can be added or not added according to actual needs. When added, it can be 0.5 parts, 1 part, 1.5 parts, 2 parts, 3 parts, etc.

[0046] In one embodiment, polyurethane, as the matrix material, can be a thermoplastic polyurethane elastomer material, which can include a soft segment portion and a hard segment portion; further, the mass ratio of the soft segment portion to the hard segment portion in the thermoplastic polyurethane elastomer material can be 1.1 to 1.3:1, for example, it can be 1.1:1, 1.2:1, 1.3:1, etc.

[0047] In one embodiment, the mass ratio of multi-walled carbon nanotubes to polymethyl methacrylate in the modified multi-walled carbon nanotubes is 1:(7-15), for example, 1:7, 1:8, 1:10, 1:12, 1:15, etc.; under this mass ratio, the conductivity permeation threshold of the composite material can be effectively reduced. Further, the mass ratio of multi-walled carbon nanotubes to doped iodine is 1:(0.1-0.3), for example, 1:0.1, 1:0.2, 1:0.3, etc.; under this mass ratio, the conductivity of the composite material can be effectively improved.

[0048] In one embodiment, the aspect ratio of the modified multi-walled carbon nanotubes is 500-1500, for example, it can be 500:1, 800:1, 1000:1, 1200:1, 1500:1, etc. Under this aspect ratio condition, the conductivity permeation threshold of the modified multi-walled carbon nanotubes in the composite material can be reduced.

[0049] The aforementioned multi-walled carbon nanotubes can be prepared by grafting purified carbon nanotubes with polymethyl methacrylate and doping with iodine.

[0050] In some embodiments, the polyamide in the modified molybdenum disulfide can be polymerized from ε-caprolactam and amino groups on the surface of molybdenum disulfide, wherein the mass ratio of molybdenum disulfide to ε-caprolactam is 1:(6-12), for example, 1:6, 1:8, 1:10, 1:12, etc.; under this mass ratio condition, it is beneficial to improve the dispersibility of modified molybdenum disulfide in the composite material.

[0051] In some embodiments, the modified molybdenum disulfide comprises molybdenum disulfide nanosheets with a particle size of 2000 mesh. The molybdenum disulfide nanosheets can further reduce the coefficient of friction of molybdenum disulfide and enhance its interfacial bonding with the polyurethane matrix.

[0052] Specifically, the modified molybdenum disulfide can be prepared by amination of the stripped molybdenum disulfide powder, followed by in-situ ring-opening polymerization with caprolactam monomer.

[0053] In some embodiments, antioxidants include, but are not limited to, at least one of antioxidant 1010 [i.e., pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]], antioxidant 1135 [i.e., isooctyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], antioxidant 245 [i.e., triethylene glycol bis[β-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionate]], and antioxidant 1076 [i.e., octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], etc. These antioxidants have good compatibility with polyurethane and good antioxidant properties, which can improve the overall lifespan of the composite material.

[0054] Secondly, embodiments of this application provide a method for preparing a composite material, such as... Figure 1 As shown, the preparation method includes the following steps:

[0055] S01: Provide the components in the composite material provided in the first aspect of this application, in parts by weight;

[0056] S02: Polyurethane, modified multi-walled carbon nanotubes, modified molybdenum disulfide and antioxidants are mixed to obtain a composite material.

[0057] This application embodiment obtains the composite material by mixing the components in each weight proportion provided in the first aspect above. This preparation method is not only simple, but the resulting composite material also has excellent electrical conductivity and wear resistance, is not easily deformed, and can be well used as a stylus tip material.

[0058] Step S01 is the raw material preparation process. The composition of each part by weight in the provided composite material is described above.

[0059] In some embodiments, the preparation steps of modified multi-walled carbon nanotubes include: mixing purified multi-walled carbon nanotubes with methyl methacrylate and an initiator and performing a heated polymerization reaction to obtain multi-walled carbon nanotubes connected with polymethyl methacrylate; mixing the multi-walled carbon nanotubes connected with polymethyl methacrylate and iodine crystals and performing heat treatment to obtain modified multi-walled carbon nanotubes.

[0060] Furthermore, the purified multi-walled carbon nanotubes can include those purified using trifluoroacetic acid as a solvent. The purification process with trifluoroacetic acid helps remove some carbonaceous particles, metal catalysts, and other impurities from the multi-walled carbon nanotubes, thereby improving their electrical conductivity.

[0061] Furthermore, trifluoroacetic acid was added during the heated polymerization reaction of purified multi-walled carbon nanotubes with methyl methacrylate and an initiator. The heated polymerization reaction was carried out under trifluoroacetic acid conditions, which allowed the multi-walled carbon nanotubes to be grafted with PMMA, thus improving the grafting efficiency.

[0062] Furthermore, the temperature for heating and polymerization of the purified multi-walled carbon nanotubes mixed with methyl methacrylate and an initiator can be 100-110°C, and the reaction time can be 20-28 hours. The temperature for heat treatment of the multi-walled carbon nanotubes linked with polymethyl methacrylate and iodine crystals can be 120-140°C, and the time can be 10-14 hours.

[0063] In some embodiments, the preparation method of modified multi-walled carbon nanotubes includes the following steps:

[0064] First, purify the multi-walled carbon nanotubes: Add 10-15 parts by weight of multi-walled carbon nanotubes to 350-450 parts by weight of trifluoroacetic acid and 2000-2500 parts by weight of DMF (N,N-dimethylformamide), and disperse by ultrasonication (20-25 kHz at 250-350 W). Then, centrifuge and stir at 5000-6000 rpm for 6-8 min. Filter and discard the supernatant. Repeat the above operation 3-5 times to obtain purified multi-walled carbon nanotubes.

[0065] Modification of purified multi-walled carbon nanotubes: 9.4-14.1 parts by weight of the purified multi-walled carbon nanotubes obtained above, 100-150 parts by weight of methyl methacrylate, and 1-2 parts by weight of initiator (such as azobisisobutyronitrile) were added to 250-300 parts by weight of trifluoroacetic acid and 1400-1700 parts by weight of DMF. The mixture was ultrasonically dispersed for 1-2 hours (350-450W at 20-25 kHz), and then heated at 100-110℃ for 20-28 hours. After cooling, the solution was filtered. The obtained product was stirred with 2000-2500 parts by weight of dichloromethane at 200-300 r / min, and then filtered again. This process was repeated 3-5 times. The product was then dried in an oven at 70-80℃ for 4-6 hours to obtain multi-walled carbon nanotubes grafted with PMMA. Then, by weight, 9.7-14.5 parts of the above-obtained PMMA-grafted multi-walled carbon nanotubes and 1-2 parts of iodine crystals were placed into a reaction vessel, quickly sealed, and placed in a resistance furnace for reaction at 120-140℃ for 10-14 hours. After the product cooled to room temperature (25-27℃), it was washed with alcohol until the washing solution was colorless, yielding iodine-doped modified multi-walled carbon nanotubes.

[0066] In some embodiments, the preparation steps of modified molybdenum disulfide include: amination treatment of the stripped molybdenum disulfide powder to obtain amino-modified molybdenum disulfide powder; and ring-opening polymerization reaction of the amino-modified molybdenum disulfide powder with ε-caprolactam monomer to obtain modified molybdenum disulfide.

[0067] Furthermore, amination can be performed using an amination reagent. The ring-opening polymerization reaction conditions can include: reacting at 180-230℃ for 1-2 hours, followed by heating to 250-300℃ for 2-4 hours.

[0068] In this embodiment, molybdenum disulfide is treated using a lithium-ion intercalation method to prepare molybdenum disulfide nanosheets, thereby reducing the friction coefficient of molybdenum disulfide and enhancing its interfacial bonding with the polyurethane matrix. The surface of the molybdenum disulfide sheets is then aminated with an amination agent (such as mercaptoethylamine) to obtain aminated molybdenum disulfide (MoS2-NH2). This is then reacted with ε-caprolactam monomer in an in-situ ring-opening polymerization reaction to obtain molybdenum disulfide-grafted polyamide (PA-g-MoS2).

[0069] In some embodiments, the preparation method of modified molybdenum disulfide includes the following steps:

[0070] Stripping molybdenum disulfide: Dissolve 80-160 parts by weight of n-butyllithium in 260-500 parts by weight of n-hexane, mix thoroughly, then add 4-8 parts by weight of molybdenum disulfide powder and pour into a reaction vessel. After cooling the mixture to room temperature, stir the reaction at 2000-2500 rpm. After the reaction is complete, filter under vacuum. Wash the obtained product with n-hexane until the washing liquid is colorless and dry to obtain the stripped molybdenum disulfide powder.

[0071] Modification of the stripped molybdenum disulfide: Again, by weight, dissolve 3.8-7.6 parts of the above-obtained molybdenum disulfide powder in 60-80 parts of deionized water, and ultrasonically disperse (150-200W at 30-40kHz) to obtain an aqueous molybdenum disulfide solution. Dissolve 2-5 parts of mercaptoethylamine in 35-50 parts of deionized water, mix thoroughly, and pour into the above molybdenum disulfide aqueous solution. Sonicate for 24 hours (150-200W at 30-40kHz). Dry the product at 80-130℃ for 2-4 hours to obtain amination-treated molybdenum disulfide powder (MoS2-NH2). Again, by weight, mix 6.6-13 parts of the above-obtained amination-treated molybdenum disulfide powder and 40-60 parts of ε-caprolactam, and melt-sonicate disperse at 70-80℃ for 1-3 hours (200-250W at 30-40kHz). After thorough mixing, add 1-5 parts of 6-aminohexanoic acid and stir at 800-1000 r / min for 1-3 h. Heat the mixed solution to 180-230℃ and react for 1-2 h, then heat to 250-300℃ and react for 2-4 h. Filter the product with boiling deionized water under back-vacuum and dry under vacuum at 70-90℃ for 4-6 h to obtain molybdenum disulfide grafted with polyamide.

[0072] Step S02 is the mixing process. It should be noted that when no antioxidant is needed in the composite material, the mixing process can be performed by directly mixing polyurethane, modified multi-walled carbon nanotubes, and modified molybdenum disulfide; when an antioxidant is needed in the composite material, the mixing process involves mixing polyurethane, modified multi-walled carbon nanotubes, modified molybdenum disulfide, and the antioxidant.

[0073] In some embodiments, the mixing process includes: melt blending at 160-165°C followed by hot pressing at 170-175°C, then cold pressing, and annealing.

[0074] This application presents a composite material prepared using a melt blending-annealing method. This process is simple, and through melt blending, polyurethane, modified multi-walled carbon nanotubes, and modified molybdenum disulfide are fully contacted and bonded together, forming a well-bonded and stable system. Annealing further enhances the formation of a multi-walled carbon nanotube-multi-walled carbon nanotube network structure, reducing the material's conductivity percolation value. Simultaneously, this unique structure induces flocculation, resulting in improved conductivity and elasticity. Consequently, the resulting composite material exhibits advantages such as high wear resistance, smooth writing, low deformation, and high conductivity.

[0075] Furthermore, the cold pressing process is carried out in a cold press at a pressure of 10-15 MPa for 1-2 hours. Furthermore, the annealing temperature is 180-185°C, specifically at the aforementioned annealing temperature and a pressure of 15-20 MPa for 1-2 hours. In this embodiment, the materials are melt-blended, hot-pressed, then cold-pressed and annealed to form a carbon composite material with high wear resistance, smooth writing surface, low deformation, and high electrical conductivity.

[0076] In some embodiments, the mixing process includes: drying 100-150 parts by weight of thermoplastic polyurethane elastomer in an oven at 110-115°C for 2-3 hours; heating a two-roll mill to 160-165°C, and then preheating the dried thermoplastic polyurethane elastomer in the gap of the mill for 3-5 minutes; then adding 1-3 parts of antioxidant for plasticizing; after uniformly wrapping the rolls, adding 6-10 parts of modified multi-walled carbon nanotubes and 10-20 parts of modified molybdenum disulfide, mixing for 5-10 minutes, and then sheeting. The resulting blend is placed in a mold, preheated on a flat vulcanizing press at 170-175°C, and then pressurized in 3-5 stages until the pressure reaches 15-20 MPa, followed by hot pressing for 10-20 minutes; then the plasticized molded product is placed in a cold press for cold pressing and allowed to cool. The cooled composite material is then annealed: the sample is placed in a mold and slowly pressurized on a flat vulcanizing machine at 180-185℃. When the pressure reaches 15-20MPa, it is held for 1-2 hours. The plasticized molded product is then placed in a cold press for cold pressing. After cooling, the annealing is completed, and the product can be removed.

[0077] In one embodiment, such as Figure 2As shown, the preparation method of the composite material in this application specifically includes: (1) purifying multi-walled carbon nanotube powder and then grafting PMMA and doping with iodine to obtain modified multi-walled carbon nanotubes; (2) peeling molybdenum disulfide powder, then amylating it with mercaptoethylamine, and then reacting it with ε-caprolactam monomer through ring-opening polymerization to obtain modified molybdenum disulfide; (3) drying and preheating thermoplastic polyurethane elastomer to obtain polyurethane-based adhesive; (4) melting and mixing the modified multi-walled carbon nanotubes, modified molybdenum disulfide, and polyurethane-based adhesive, and then annealing to obtain the composite material.

[0078] Thirdly, embodiments of this application provide a stylus, including a pen tip, the material of which includes the composite material provided in the first aspect of this application and / or the composite material prepared by the preparation method provided in the second aspect of this application.

[0079] The stylus tip material of the embodiment of this application uses the composite material unique to this application. Therefore, such a stylus has the advantages of high wear resistance, low deformation and high conductivity when writing on the screen. Because the writing is smooth, it can greatly improve the user experience.

[0080] The following description is based on specific embodiments.

[0081] Example 1

[0082] A composite material, by weight, comprises 100 parts of thermoplastic polyurethane elastomer (where the mass ratio of soft segment to hard segment is 1.2:1), 6 parts of modified multi-walled carbon nanotubes, 10 parts of modified molybdenum disulfide, and 1 part of antioxidant. The preparation method of this composite material includes the following steps:

[0083] S1: Preparation of modified multi-walled carbon nanotubes

[0084] By weight, 10 parts of multi-walled carbon nanotubes were added to 350 parts of trifluoroacetic acid and 2000 parts of DMF, and ultrasonically dispersed for 20 min (ultrasonic conditions: 20 kHz, 250 W), followed by centrifugation at 5000 r / min for 6 min. The supernatant was filtered off, and the above operation was repeated 3 times to obtain purified multi-walled carbon nanotubes.

[0085] Re-add 9.4 parts by weight of the purified multi-walled carbon nanotubes obtained above, 100 parts by weight of methyl methacrylate, and 1 part by weight of azobisisobutyronitrile to 250 parts by weight of trifluoroacetic acid and 1400 parts by weight of DMF. Disperse the mixture ultrasonically for 1 hour (ultrasonic conditions: 20 kHz, 350 W), then heat at 105 °C for 24 hours. After cooling, filter the solution. Stir the resulting product with 2000 parts by weight of dichloromethane at 200 rpm for 15 minutes, then filter again. Repeat this process three times. Finally, dry the product in a 70 °C oven for 4 hours to obtain PMMA-grafted multi-walled carbon nanotubes.

[0086] Re-weighted, 9.7 parts of the above-obtained PMMA-grafted multi-walled carbon nanotubes and 1 part of iodine crystals were placed into a reaction vessel, quickly sealed, and placed in a resistance furnace. The temperature was set at 130°C, the heating rate was 0.5°C / min, and the reaction was carried out for 12 hours. After the product cooled to room temperature, it was washed with alcohol until the washing solution was colorless, yielding the modified multi-walled carbon nanotubes.

[0087] S2: Preparation of modified molybdenum disulfide

[0088] By weight, 80 parts of n-butyllithium were dissolved in 260 parts of n-hexane, mixed thoroughly, and then 4 parts of molybdenum disulfide powder were added. The mixture was poured into a reactor and reacted at 100°C for 4 hours. After the mixture was cooled to room temperature, it was stirred at 2000 r / min for 48 hours. After the reaction was completed, it was filtered under vacuum. The product was washed with n-hexane until the washing liquid was colorless, and then dried at 60°C for 2 hours to obtain the stripped molybdenum disulfide powder.

[0089] Re-dissolve 3.8 parts by weight of the above-obtained stripped molybdenum disulfide powder in 60 parts of deionized water and ultrasonically disperse for 12 h (ultrasonic conditions: 30 kHz, 150 W) to obtain an aqueous solution of molybdenum disulfide. Dissolve 2 parts of mercaptoethylamine in 35 parts of deionized water, mix thoroughly, and pour into the above aqueous solution of molybdenum disulfide. Sonicate for 24 h (ultrasonic conditions: 30 kHz, 150 W). Dry the product at 80 °C for 2 h to obtain aminated molybdenum disulfide powder.

[0090] Re-disperse 6.6 parts by weight of the above-obtained amination-modified molybdenum disulfide powder with 40 parts by weight of ε-caprolactam at 70°C using ultrasonication for 1 hour (ultrasonic conditions: 30 kHz, 200 W). After thorough mixing, add 1 part of 6-aminohexanoic acid and stir at 800 r / min for 1 hour. Heat the mixture to 180°C for 1 hour, then heat to 250°C for 2 hours. Filter the product with boiling deionized water using back-vacuum filtration and dry under vacuum at 70°C for 4 hours to obtain modified molybdenum disulfide.

[0091] S3: Based on the required weight proportions of each component for the composite material, dry 100 parts of thermoplastic polyurethane elastomer in an oven at 110℃ for 2 hours; heat the two-roll mill to 160℃, then place the dried thermoplastic polyurethane elastomer into the gap of the mill for preheating for 3 minutes. Add 1 part of antioxidant for plasticizing (roller gap 2mm, roll speed 60r / min); after uniformly wrapping the rolls, add 6 parts of modified multi-walled carbon nanotubes and 10 parts of modified molybdenum disulfide, mix for 5 minutes, and then sheet. Place the resulting blend into a mold, preheat it on a flat vulcanizing machine at 170℃, then apply pressure in 3 stages. When the pressure reaches 15MPa, hot press for 10 minutes, then place the plasticized molded product into a cold press for cold pressing and allow it to cool. The cooled composite material is then annealed: the sample is placed in a mold and pressurized on a flat vulcanizing machine at 180°C. When the pressure reaches 15MPa, it is held for 1 hour. The plasticized molded product is then placed in a cold press for cold pressing. After cooling, the annealing is completed, and the product can be removed.

[0092] Example 2

[0093] A composite material. By weight, it comprises 125 parts of thermoplastic polyurethane elastomer, 8 parts of modified multi-walled carbon nanotubes, 15 parts of modified molybdenum disulfide, and 2 parts of antioxidant.

[0094] Except for the different weights of each component compared to Example 1, the raw materials and process parameters used in the preparation of this composite material are the same as those in Example 1.

[0095] Example 3

[0096] A composite material. By weight, it comprises 150 parts of thermoplastic polyurethane elastomer, 10 parts of modified multi-walled carbon nanotubes, 20 parts of modified molybdenum disulfide, and 3 parts of antioxidant.

[0097] Except for the different weights of each component compared to Example 1, the raw materials and process parameters used in the preparation of this composite material are the same as those in Example 1.

[0098] Comparative Example 1

[0099] A composite material, differing from Example 2 only in that the modified multi-walled carbon nanotubes of Example 2 are replaced with unmodified multi-walled carbon nanotubes (i.e., purified multi-walled carbon nanotubes).

[0100] Comparative Example 2

[0101] A composite material, differing from Example 2 only in that the modified molybdenum disulfide of Example 2 is replaced with unmodified molybdenum disulfide (i.e., the stripped molybdenum disulfide).

[0102] Performance testing

[0103] The composite materials prepared in Examples 1-3 and Comparative Examples 1-2 were subjected to performance tests. The specific test methods for friction resistance (wear amount), friction coefficient, hardness, electrical conductivity, and deformation resistance (deformation amount) are shown in Table 1. The test data results are shown in Table 2.

[0104] Table 1

[0105]

[0106] Table 2

[0107] Example 1 64 98 <0.4mm 0.246 <0.6mm Example 2 71 83 <0.2mm 0.213 <0.3mm Example 3 75 75 <0.2mm 0.201 <0.4mm Comparative Example 1 63 196 <0.5mm 0.312 <0.7mm Comparative Example 2 60 86 <0.7mm 0.428 <1.1mm

[0108] As shown in Table 1, Example 2 of this application exhibits higher hardness and lower electrical resistance (i.e., better conductivity) compared to Comparative Examples 1-2. Furthermore, it shows lower deformation and coefficient of friction, resulting in less wear. Therefore, the composite material of Example 2 uses polyurethane as the matrix material. By adding modified multi-walled carbon nanotubes and modified molybdenum disulfide to achieve a uniform fraction of multi-walled carbon nanotubes and molybdenum disulfide in the polyurethane matrix, the composite material exhibits better conductivity and wear resistance compared to Comparative Examples 1-2, and is less prone to deformation, making it well-suited for use as a stylus tip material. Examples 1 and 3 also achieve corresponding improvements by adjusting the proportions of each component.

[0109] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A composite material, characterized in that, The components include the following parts by weight: 100-150 parts of polyurethane 6-10 parts of modified multi-walled carbon nanotubes 10-20 parts of modified molybdenum disulfide Antioxidant 0-3 parts; The modified multi-walled carbon nanotubes include multi-walled carbon nanotubes and polymethyl methacrylate connected to the multi-walled carbon nanotubes, wherein the multi-walled carbon nanotubes are doped with iodine; the modified molybdenum disulfide includes molybdenum disulfide and polyamide connected to the molybdenum disulfide. The preparation steps of the modified multi-walled carbon nanotubes include: mixing purified multi-walled carbon nanotubes with methyl methacrylate and an initiator and heating them for polymerization to obtain multi-walled carbon nanotubes connected with methyl methacrylate; mixing the multi-walled carbon nanotubes connected with methyl methacrylate and iodine crystals and heat-treating them to obtain the modified multi-walled carbon nanotubes. The preparation steps of the modified molybdenum disulfide include: amination treatment of the stripped molybdenum disulfide powder to obtain amino-modified molybdenum disulfide powder; and ring-opening polymerization reaction of the amino-modified molybdenum disulfide powder with ε-caprolactam monomer to obtain the modified molybdenum disulfide.

2. The composite material as described in claim 1, characterized in that, The mass ratio of the multi-walled carbon nanotubes to the polymethyl methacrylate is 1:(7-15); and / or The mass ratio of the multi-walled carbon nanotubes to the doped iodine is 1:(0.1-0.3).

3. The composite material as described in claim 1, characterized in that, The mass ratio of molybdenum disulfide to ε-caprolactam is 1:(6-12).

4. The composite material according to any one of claims 1-3, characterized in that, The aspect ratio of the multi-walled carbon nanotubes is 500-1500; and / or The molybdenum disulfide comprises molybdenum disulfide powder with a particle size of 2000 mesh.

5. A method for preparing a composite material, characterized in that, Includes the following steps: Provide the components in parts by weight of the composite material according to any one of claims 1-4; The polyurethane, the modified multi-walled carbon nanotubes, the modified molybdenum disulfide, and the antioxidant are mixed to obtain the composite material.

6. The preparation method according to claim 5, characterized in that, The purified multi-walled carbon nanotubes include multi-walled carbon nanotubes purified with trifluoroacetic acid; and / or, The heating polymerization reaction was carried out under trifluoroacetic acid conditions.

7. The preparation method according to any one of claims 5-6, characterized in that, The mixing process includes: melt blending at 160-165℃ followed by hot pressing at 170-175℃, then cold pressing, and annealing.

8. A stylus, comprising a pen tip, characterized in that, The material of the pen tip includes the composite material according to any one of claims 1-4 or the composite material prepared by the preparation method according to any one of claims 5-7.

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