Polymer material with high dielectric constant
By using the phase separation structure of two-phase polymers in high-dielectric constant polymer materials to form more microcapacitor structures, the cost and processability problems of existing materials when improving dielectric performance are solved, and efficient dielectric performance improvement and material performance stability are achieved.
Patent Information
- Application Number
- CN202510000909.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-02
- Publication Date
- 2025-05-23
AI Technical Summary
When improving dielectric properties, existing high-dielectric constant polymer materials often require a higher filling amount, resulting in an increase in material cost and a decrease in processability. The large amount of addition of conductive fillers will damage the physical properties of the material.
By using at least two-phase polymer and conductive filler, a phase separation structure of the second phase creates a locally filled-free region in the matrix phase, reducing the distance between the conductive fillers and forming more microcapacitance structures, thereby increasing the dielectric constant.
With the same amount, the dielectric constant of the material is greatly improved, the amount of conductive filler is used is reduced, the damage to material properties is avoided, the process flow is simplified, and the production cost is reduced.
Smart Images
Figure CN120025677A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of polymer material processing, and in particular relates to a high dielectric constant polymer material. Background Art
[0002] With the rapid development of electronic technology, the demand for high-performance polymer dielectric materials is growing. Due to their excellent energy storage properties, these materials have shown great application potential in fields such as capacitors, capacitive sensors, and nano-friction generators. In particular, high dielectric constant polymer materials have received special attention due to their low loss and high energy density storage capabilities under high frequency conditions.
[0003] At present, the methods for improving the dielectric properties of polymers mainly focus on two aspects: one is to use composite barium titanate (BaTiO 3 ) and other piezoelectric ceramic materials; the second is by adding conductive fillers, such as carbon nanotubes, graphene, etc. Although both methods can improve the dielectric properties of polymers to a certain extent, they also bring their own challenges. For example, when piezoelectric ceramics are used as fillers, in order to achieve a significant dielectric enhancement effect, a higher filling amount is usually required, which not only increases the cost of the material, but may also lead to a decrease in the flexibility and processability of the material. Although the use of conductive fillers can effectively improve the dielectric constant, the high price and impact on mechanical properties limit its widespread application, and large-scale addition will also damage the physical properties of the material.
[0004] In order to solve the above problems, researchers began to explore other possible solutions in order to achieve improved dielectric properties while reducing the use of fillers. On the one hand, improving the compatibility between fillers and polymer matrices becomes an option, but this often means a more complicated process flow. On the other hand, it is particularly important to start directly from the polymer processing process and find new ways to simplify the process and reduce costs. For example, by controlling the phase structure during the polymer blending process to achieve higher dielectric properties at the same amount of conductive filler, the purpose of reducing the amount of conductive filler can be achieved. At the same time, compared with modifying the filler, this method is simpler to operate and easier to industrialize. Summary of the invention
[0005] The object of the present invention is to provide a high dielectric constant polymer material, the raw materials of which include at least two phases of polymer and conductive filler, the at least two phases of polymer are thermodynamically immiscible with each other, and the distance between the conductive fillers in the matrix phase is reduced by the phase separation volume exclusion effect of the second phase that is immiscible with the matrix phase, thereby promoting the conductive filler to form a microcapacitor in the matrix phase.
[0006] The principle of the present invention is that due to the existence of the second phase and the phase separation structure of the two-phase polymer, it can create a local unfilled area in the matrix phase, so that the distance between the conductive fillers in the filling area is greatly reduced, thereby forming more micro-capacitor structures, and this microstructure can effectively increase the dielectric constant, while avoiding the negative impact of adding a large amount of conductive fillers, and the conductive fillers are distributed in the matrix phase through the regulation of the affinity of the polymer and the conductive filler, so as to obtain a composite material of a polymer and a conductive filler with a selectively dispersed structure. The selectively dispersed structure reduces the distance between the conductive fillers, thereby forming more micro-capacitor structures in the polymer matrix, thereby greatly improving the dielectric constant of the material under the same dosage. The obtained polymer / conductive filler composite material is subjected to hot pressing molding by a flat vulcanizer or injection molding by an injection molding machine, i.e., a polymer material with a high dielectric constant is obtained.
[0007] In a possible implementation manner, the distribution state of the at least two phases of polymer and the conductive filler is as follows: When the at least two phases of polymer are sea-island phases, the conductive filler is dispersed in the sea phase; When the at least two phases of polymers are both in the form of continuous phases, the conductive filler is dispersed in any one of the continuous phases.
[0008] Compared with the prior art, the present invention has the following advantages by limiting the distribution state: 1. Advantages in the sea-island phase structure (conductive fillers are dispersed in the sea phase) Efficient use of space: In the sea-island phase structure, the conductive filler is effectively dispersed in the "sea" phase, while the "island" phase, as an immiscible second phase, plays a role in volume exclusion. This layout can maximize the use of available space, allowing the conductive filler to be arranged more densely in a limited area, thereby forming more micro-capacitor units and improving dielectric properties.
[0009] Wider adjustable range: For structures where the conductive filler tends to be dispersed in the sea phase, it is not limited to a certain extent by the ratio of the two-phase polymers.
[0010] Enhanced mechanical strength: The "island" phase not only acts as a physical barrier to prevent direct contact between conductive fillers, but also shares external stress, enhancing the overall mechanical strength and durability of the composite material.
[0011] Simplified manufacturing process: The sea-island phase structure in which the conductive filler is dispersed in the sea phase usually has a simpler preparation process and does not require complicated molding steps to achieve an ideal filler distribution. This not only reduces the difficulty of production, but also improves production efficiency, which is conducive to large-scale industrial applications.
[0012] 2. Advantages in continuous phase structure (conductive fillers are dispersed in any continuous phase) Flexibility and Adjustability: When both phases are continuous, the conductive filler can be optimally distributed in either phase, which gives designers greater flexibility to adjust the dielectric properties and other physical properties of the material. For example, the proportion of different phases can be changed or a specific phase can be selected as the main medium for carrying the conductive filler to meet specific application requirements.
[0013] Uniform dispersion and performance consistency: In the continuous phase, conductive fillers are more easily dispersed evenly, avoiding the problem of local concentration being too high or too low, and ensuring the stability and consistency of the overall performance of the material. In addition, uniform dispersion also helps to reduce internal defects in the material and improve its reliability in long-term use.
[0014] In a possible implementation, the conductive filler is a carbon material or a metal conductor.
[0015] Furthermore, the carbon material is selected from at least one of carbon nanotubes, graphene, reduced graphene oxide, graphite, and carbon black, and the metal conductor is selected from zinc oxide and / or silver particles.
[0016] Compared with the prior art, the present invention selects the above-mentioned conductive fillers for the following purposes: for example, carbon nanotubes have extremely high aspect ratios and excellent electrical conductivity, can form an effective conductive network in a polymer matrix, and significantly improve the dielectric constant; for example, graphene is a carbon material with a single layer or a few layers of atomic thickness, and has excellent electrical conductivity and thermal conductivity. It can be evenly dispersed in a polymer matrix to form an efficient conductive path, and improve dielectric properties without affecting the flexibility of the material; for example, carbon black, as a traditional conductive filler, has been widely used in rubber, plastic and other industries. Its particles are small and easy to disperse, and can effectively increase the conductivity of polymers.
[0017] In a possible embodiment, when the at least two phases of polymer are sea island phases and the conductive filler tends to be dispersed in the island phase, the preparation steps of the high dielectric constant polymer material are as follows: the conductive filler is first mixed with the sea phase, and then the island phase is added for blending, wherein the blending method is melt blending through an extruder or an internal mixer, and then hot pressing through a flat plate vulcanizer. Compared with the prior art, the present invention first mixes the conductive filler with the sea phase, and then adds the island phase for blending. This step-by-step addition method can achieve the effect of dynamically controlling the dispersion.
[0018] In one possible embodiment, when the at least two phases of polymers are in the form of continuous phases, the preparation steps of the high dielectric constant polymer material are as follows: melt blending the components of the at least two phases of polymers and the conductive filler through an extruder or an internal mixer, then hot pressing through a flat plate vulcanizer, and finally saturating and releasing the pressure for foaming through an autoclave.
[0019] Compared with the existing technology, since all ingredients (including two continuous phase polymers and conductive fillers) can be mixed at one time in the same equipment, this greatly simplifies the production process, reduces the number of operating steps and required equipment, and when melt blending in an extruder or internal mixer, key parameters such as temperature and pressure can be precisely controlled to ensure uniform dispersion of each component and improve the consistency of product quality. By optimizing the distribution of fillers in any continuous phase, the use of expensive conductive fillers can be reduced without sacrificing dielectric properties, thereby reducing production costs. The uniform dispersion of conductive fillers in any continuous phase helps to maintain the uniformity and stability of the internal structure of the material, thereby ensuring the consistency and long-term reliability of dielectric properties.
[0020] In one possible embodiment, when the at least two phases of polymer are sea island phases and the conductive filler tends to be dispersed in the sea phase, the preparation steps of the high dielectric constant polymer material are as follows: melt blending the components of the at least two phases of polymer and the conductive filler through an extruder or an internal mixer, and then hot pressing through a flat plate vulcanizer.
[0021] Since the conductive fillers are mainly distributed in the "sea" phase, the "island" phase, as an immiscible second phase, plays a role of volume exclusion, allowing the conductive fillers to be arranged more densely in a limited area to form more micro-capacitor units, thereby improving the dielectric properties. The presence of the "island" phase effectively prevents direct contact and agglomeration between the conductive fillers in the "sea" phase, ensuring the uniformity and stability of the internal structure of the material, and thus ensuring the consistency of the dielectric properties. All ingredients (including two polymer components and conductive fillers) can be mixed at one time in the same equipment, which greatly simplifies the production process and reduces the number of operating steps and required equipment.
[0022] In a possible implementation manner, the parameters of melt blending are as follows: temperature is 190° C., rotation speed is 50 rpm, and time is 8 min.
[0023] Compared with the prior art, the effect of the above method adopted in the present invention is that: the temperature of 190°C is sufficient to completely melt the polymer matrix, ensuring good contact and mixing between the components, which is crucial for forming a uniform composite material. At the same time, this temperature is selected moderately, which can not only meet the melting requirements but also will not cause thermal degradation of the polymer or conductive filler, thereby protecting the physical and chemical properties of the material. Moreover, the appropriate high temperature can increase the fluidity of the polymer, making the conductive filler easier to disperse, which is helpful to form an ideal microstructure, such as a microcapacitor unit; the rotation speed of 50rpm provides a moderate shear force, which can effectively promote the mixing and dispersion of the materials without excessively destroying the structure of the polymer chain or the conductive filler; 8 minutes is enough for all components to reach a good mixing state, forming a stable sea island phase structure or a continuous phase structure, while ensuring that the conductive filler is uniformly dispersed in the sea phase or any continuous phase.
[0024] In one possible implementation, the temperature of hot pressing is 190°C.
[0025] The temperature of 190°C is sufficient to keep the polymer matrix in good fluidity, ensuring sufficient contact and bonding between the components. At appropriately high temperatures, the polymer segments can move more freely, which helps to enhance the interfacial interaction between the island phase and the sea phase and between the conductive filler and the polymer matrix, thereby improving the overall mechanical strength and durability of the material.
[0026] In a possible implementation, 20 MPa supercritical carbon dioxide is introduced into the autoclave, and after saturation for half an hour, the pressure is released for foaming.
[0027] Supercritical carbon dioxide (scCO 2 ) is an environmentally friendly and efficient foaming agent that can penetrate deeply into the polymer matrix at a pressure of 20 MPa. When the pressure is subsequently released, scCO 2 Rapidly expand and escape, forming a uniform and fine microporous structure. This structure not only reduces the weight of the material, but also gives it compressibility and flexibility. In addition, the microporous structure can also reduce the direct contact between conductive fillers, avoid the formation of unnecessary conductive paths, and thus maintain good insulation properties. BRIEF DESCRIPTION OF THE DRAWINGS
[0028] Figure 1 This is a dispersion diagram of the high dielectric constant polymer material prepared in Example 1 of the present invention; Figure 2 This is a dispersion diagram of a high dielectric constant polymer material prepared in Example 2 of the present invention; Figure 3 This is a dispersion diagram of a high dielectric constant polymer material prepared in Example 3 of the present invention; Figure 4 This is a dispersion diagram of the polymer material obtained in Comparative Example 1 of the present invention. DETAILED DESCRIPTION
[0029] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below. It should be noted that the following embodiments are only used to illustrate the implementation method and typical parameters of the present invention, and are not used to limit the parameter range described in the present invention. Reasonable changes derived therefrom are still within the scope of protection of the claims of the present invention.
[0030] It should be noted that the endpoints and any values of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoint values of each range, the endpoint values of each range and the individual point values, and the individual point values can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed in this article.
[0031] Unless otherwise defined, all terms, symbols and other scientific terms used herein are intended to have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. In some cases, terms with conventionally understood meanings are defined herein for the purpose of clarification or ease of reference, and such definitions herein should not be construed as indicating significant differences from conventional understandings in the art. The technical methods described or cited herein are generally well understood by those skilled in the art and are adopted by conventional methods. Unless otherwise stated, the use of commercially available kits, reagents and instruments is carried out in accordance with the protocols and parameters given by the manufacturer.
[0032] The technical effects of the present invention are described below in conjunction with specific embodiments.
[0033] Example 1 The present embodiment provides a method for preparing a high dielectric constant polymer material, and the specific operating steps are: thermoplastic polyurethane, polyolefin elastomer and multi-walled carbon nanotubes are melt-blended in a mass fraction of 80 / 20 / 1.5 through an internal mixer at 190°C and 50 rpm for 8 minutes to obtain a thermoplastic polyurethane composite material, and then the material is hot-pressed at 190°C on a flat vulcanizer, and the hot-pressed block is placed in an autoclave, and 20MPa supercritical carbon dioxide is introduced. After saturation for half an hour, the pressure is quickly released for foaming to obtain a high dielectric constant polyurethane foam material.
[0034] After testing, the weight loss rate of the high dielectric constant polyurethane foam material prepared in this embodiment is 44%, and the dielectric constant of the foam material at 100 Hz is 217.2, the dielectric loss is 0.91, and the dispersion of the polymer is as follows: Figure 1As shown in the figure, it can be seen that the conductive filler is selectively dispersed in the thermoplastic polyurethane phase, that is, the sea phase. The island phase is a polyolefin elastomer phase, and it can be clearly seen from the figure that there is no conductive filler distributed therein.
[0035] Example 2 The present embodiment provides a method for preparing a high dielectric constant polymer material, and the specific operating steps are: thermoplastic polyurethane, polyolefin elastomer and multi-walled carbon nanotubes are melt-blended in a mass fraction of 60 / 40 / 1.5 through an internal mixer at 190°C and 50 rpm for 8 minutes to obtain a thermoplastic polyurethane composite material, and then the material is hot-pressed at 190°C on a flat vulcanizer, and the hot-pressed block is placed in an autoclave, and 20MPa supercritical carbon dioxide is introduced. After saturation for half an hour, the pressure is quickly released for foaming to obtain a high dielectric constant polyurethane foam material.
[0036] After testing, the weight loss rate of the high dielectric constant polyurethane foam material prepared in this embodiment is 47%, and the dielectric constant of the foam material at 100 Hz is 241.3, and the dielectric loss is 1.22. Compared with the dispersion of the dielectric constant polymer in Comparative Example 1, Figure 2 As shown, from Figure 2 It can be seen that the conductive filler is selectively dispersed in the thermoplastic polyurethane phase, that is, the sea phase. The island phase is a polyolefin elastomer phase, and it can be clearly seen from the figure that there is no conductive filler distributed therein.
[0037] Example 3 This embodiment provides a method for preparing a thermoplastic polyurethane foam material with a high dielectric constant, and the specific operation steps are: melt blending thermoplastic polyurethane, polyolefin elastomer and multi-walled carbon nanotubes in a mass fraction of 60 / 40 / 1 through an internal mixer at 190°C and 50rpm for 8 minutes to obtain a thermoplastic polyurethane composite material, and then hot pressing the material in a flat vulcanizer at 190°C. The hot-pressed block is placed in an autoclave, and 20MPa supercritical carbon dioxide is introduced. After saturation for half an hour, the pressure is quickly released for foaming, and a thermoplastic polyurethane foam material with a high dielectric constant is obtained.
[0038] After testing, the weight loss rate of the thermoplastic polyurethane foam material prepared in this embodiment is 43%, and the dielectric constant of the foam material at 100 Hz is 92.4, and the dielectric loss is 0.66. It can be seen that compared with the dielectric constant in Comparative Example 1, the same level is achieved at a lower content of conductive filler, which further proves that the method proposed in the present invention to promote the formation of microcapacitors through selective dispersion structure to improve the dielectric constant has significant advantages. The dispersion of the polymer is shown in FIG. Figure 3As shown in the figure, the conductive filler is selectively dispersed in the thermoplastic polyurethane phase, that is, the sea phase. The island phase is a polyolefin elastomer phase, and it can be clearly seen from the figure that there is no conductive filler distributed therein.
[0039] Example 4 The present embodiment provides a method for preparing a thermoplastic polyurethane material with a high dielectric constant. The specific operation steps are: thermoplastic polyurethane, polyolefin elastomer and carbon black are melt-blended in a mass fraction of 70 / 30 / 5 through an internal mixer at 190° C. and 50 rpm for 8 minutes to obtain a thermoplastic polyurethane composite material, and then the material is hot-pressed in a flat vulcanizer at 190° C. to obtain a thermoplastic polyurethane material with a high dielectric constant.
[0040] After testing, the dielectric constant of the polymer material at 80Hz is 114.5, and the dielectric loss is 0.49. Compared with the dielectric constant in Comparative Example 2, it reaches a higher level at the same content of conductive filler, further proving that the method proposed in the present invention of promoting the formation of microcapacitors through selectively dispersed structures to improve the dielectric constant has significant advantages.
[0041] Example 5 This embodiment provides a method for preparing a thermoplastic polyurethane material, and the specific operation steps are: melt-blending thermoplastic polyurethane, polyolefin elastomer and carbon black in a mass fraction of 80 / 20 / 5 at 190° C. and 50 rpm for 8 minutes in an internal mixer to obtain a thermoplastic polyurethane composite material, and then hot-pressing the material at 190° C. in a flat vulcanizer to obtain a thermoplastic polyurethane material.
[0042] After testing, the dielectric constant of the polymer material at 80 Hz is 21.8, and the dielectric loss is 0.08. Compared with the dielectric constant in Comparative Example 2, it reaches a higher level at the same content of conductive filler, further proving that the method proposed in the present invention of promoting the formation of microcapacitors through selectively dispersed structures to improve the dielectric constant has significant advantages.
[0043] Comparative Example 1 This comparative example provides a thermoplastic elastomer foam material prepared by ordinary melt blending, which is intended to be compared with the embodiment, so as to prove the advantages of the method proposed by the present invention of promoting the formation of microcapacitors through selective dispersion structure to improve the dielectric constant of the material. The specific operation steps are: thermoplastic polyurethane and multi-walled carbon nanotubes are melt blended for 8 minutes at 50rpm at 190°C through an internal mixer according to a mass fraction of 100 / 1.5 to obtain a thermoplastic polyurethane composite material, and then the material is hot-pressed at 190°C on a flat vulcanizer. The hot-pressed block is placed in an autoclave, and 20MPa supercritical carbon dioxide is introduced. After saturation for half an hour, the pressure is quickly released and foamed, and a thermoplastic polyurethane foam material with a high dielectric constant and a weight loss rate of 48% is obtained.
[0044] After testing, the dielectric constant of the foam material at 100 Hz is 100.2, and the dielectric loss is 0.5. The dielectric constant of the comparative example is significantly lower than that of the same conductive filler in the embodiment. The dispersion of the polymer is as follows: Figure 4 As shown, the polymer is a single phase in which the conductive filler is uniformly dispersed.
[0045] Comparative Example 2 This comparative example provides a thermoplastic polyurethane elastomer material prepared by ordinary melt blending, which is intended to be compared with the embodiment to prove the advantages of the method proposed by the present invention of promoting the formation of microcapacitors through selective dispersion structure to improve the dielectric constant of the material. The specific operation steps are: thermoplastic polyurethane and multi-walled carbon nanotubes are melt blended in an internal mixer at 190°C and 50rpm for 8 minutes according to a mass fraction of 100 / 5 to obtain a thermoplastic polyurethane composite material, and then the material is hot-pressed at 190°C in a flat vulcanizer.
[0046] After testing, the dielectric constant of the polymer material at 80Hz is 13.4, and the dielectric constant of the comparative example is significantly lower than the dielectric constant of the same conductive filler in the embodiment. Although the disclosure is disclosed as above, the protection scope of the disclosure is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the disclosure, and these changes and modifications will fall within the protection scope of the present invention.
Claims
1. A high dielectric constant polymer material, characterized in that: The raw materials of the high dielectric constant polymer material include at least two phases of polymer and conductive filler. The at least two phases of polymer are thermodynamically immiscible with each other. The volume exclusion effect of the second phase that is immiscible with the matrix phase reduces the distance between the conductive fillers in the matrix phase, thereby promoting the conductive fillers to form microcapacitors in the matrix phase.
2. The high dielectric constant polymer material according to claim 1, characterized in that: The distribution state of the at least two phases of polymer and conductive filler is as follows: When the at least two phases of polymer are sea-island phases, the conductive filler is dispersed in the sea phase; When the at least two phases of polymers are both in the form of continuous phases, the conductive filler is dispersed in any one of the continuous phases.
3. The high dielectric constant polymer material according to claim 1, characterized in that: The conductive filler is a carbon material or a metal conductor.
4. The high dielectric constant polymer material according to claim 1, characterized in that: The carbon material is selected from at least one of carbon nanotubes, graphene, reduced graphene oxide, graphite, and carbon black, and the metal conductor is selected from zinc oxide and / or silver particles.
5. The high dielectric constant polymer material according to claim 1, characterized in that: When the at least two phases of polymer are sea island phases and the conductive filler tends to be dispersed in the island phase from a thermodynamic point of view, the preparation steps of the high dielectric constant polymer material are as follows: the conductive filler is first blended with the sea phase and then blended with the island phase, so as to kinetically control the distribution of the conductive filler in the sea phase, wherein the blending method is melt blending through an extruder or an internal mixer, and then hot pressing molding through a flat plate vulcanizer or injection molding through an injection molding machine.
6. The high dielectric constant polymer material according to claim 1, characterized in that: When the at least two-phase polymer is a sea-island phase and the conductive filler tends to be dispersed in the sea phase from a thermodynamic point of view, the preparation steps of the high dielectric constant polymer material are as follows: directly blending the conductive filler with the two-phase polymer, wherein the blending method is melt blending through an extruder or an internal mixer, and then hot pressing molding through a flat plate vulcanizer or injection molding through an injection molding machine.
7. The high dielectric constant polymer material according to claim 1, characterized in that: When the at least two phases of polymer are both in the form of continuous phases, the preparation steps of the high dielectric constant polymer material are as follows: melt blending the components of the at least two phases of polymer and the conductive filler through an extruder or an internal mixer, and then hot pressing through a flat plate vulcanizer or injection molding through an injection molding machine.
8. The high dielectric constant polymer material according to any one of claims 5 to 7, characterized in that: The parameters of melt blending are as follows: temperature is 190°C, rotation speed is 50 rpm, and time is 8 min.
9. The high dielectric constant polymer material according to any one of claims 5 to 7, characterized in that: The temperature of hot pressing was 190°C.