阅读说明：本技术 可宽温使用的柔性薄膜电容及其制备方法 (Flexible thin film capacitor capable of being used at wide temperature and preparation method thereof ) 是由 李峰 刘侠侠 陶玉红 李露 卢星华 袁启斌 于 2019-10-14 设计创作，主要内容包括：本发明提供一种可宽温使用的柔性薄膜电容及其制备方法,通过使用两种不同的单体或预聚物进行加热固化,在介电材料层中形成互穿网络聚合物,通过扩宽聚合物的玻璃化转变温度,改善介电材料层的介电常数在0～80℃使用温度范围内出现的介电常数变化过大问题,并且把介电材料层的介电常数在使用温度范围内随温度变化率有效控制在10％以内。(The invention provides a flexible thin-film capacitor capable of being used at a wide temperature and a preparation method thereof, wherein two different monomers or prepolymers are used for heating and curing to form an interpenetrating network polymer in a dielectric material layer, the problem of overlarge change of the dielectric constant of the dielectric material layer within the use temperature range of 0-80 ℃ is solved by widening the glass transition temperature of the polymer, and the dielectric constant of the dielectric material layer within the use temperature range is effectively controlled within 10 percent along with the change rate of the temperature.)

1. A preparation method of a flexible thin film capacitor is characterized by comprising the following steps:

preparing a dispersion liquid, wherein the dispersion liquid comprises a first monomer, a curing agent, a second monomer, an initiator, a nano inorganic filler and a solvent;

coating the dispersion liquid on the surface of a first metal film, drying at low temperature to remove a solvent, and forming a dielectric material precursor layer on the surface of the first metal film;

covering a second metal film on the surface of the dielectric material precursor layer far away from the first metal film to form a film capacitor precursor; and

and heating and curing the film capacitor precursor to enable the first monomer to perform in-situ polymerization reaction under the action of the curing agent and the second monomer to perform in-situ polymerization reaction under the action of the initiator respectively to form a dielectric material layer with an interpenetrating polymer network, thereby preparing the flexible film capacitor.

2. The method according to claim 1, wherein the preparing the dispersion comprises the steps of: uniformly mixing 10-30 wt% of a first monomer, 10-30 wt% of a second monomer, 0.5-5 wt% of a curing agent, 0.01-5 wt% of an initiator, 40-60 wt% of a nano inorganic filler and the balance of a solvent to obtain the dispersion, wherein the sum of the mass percentages of the components is 100 wt%.

3. The method of claim 2, wherein: the step of uniformly mixing the prepared dispersion liquid comprises grinding; preferably, the grinding is performed on a grinder, and the grinding is performed 4 to 6 times at a rotation speed of 1000 to 2000 rpm.

4. The production method according to claim 1 or 2, characterized in that: wherein the first monomer undergoes addition polymerization, polycondensation reaction or ring-opening polymerization reaction only under the action of the curing agent;

preferably, the first monomer is selected from one or more of epoxy resin, polyurethane, reactive silicone and cyclic monomer; and/or the curing agent is selected from one or more of epoxy curing agent, polyurethane curing agent, organic silicon polyol and ring-opening polymerization initiator.

5. The production method according to claim 1 or 2, characterized in that: the second monomer is subjected to free radical polymerization reaction only under the action of the initiator;

preferably, the second monomer is selected from one or more of acrylic monomers, acrylic prepolymers, styrene, unsaturated polyesters; and/or the initiator is a free radical initiator and is selected from one or more of organic amine, acid anhydride, imidazole and derivatives thereof, peroxide, isonitrile acid prepolymer and organic metal compounds.

6. The method of claim 1, wherein: the low-temperature drying step is drying for 10-20 minutes at 40-60 ℃; and/or

The heating and curing step is to cure the mixture for 0.5 to 5 hours at a temperature of between 100 and 150 ℃.

7. The production method according to claim 1 or 2, characterized in that: the nano inorganic filler is selected from one or more of barium sodium titanate, barium titanate, copper calcium titanate, strontium titanate, barium strontium titanate, calcium titanate, barium calcium titanate, lead zirconate titanate, lead sodium titanate and lead titanate; and/or

The nano inorganic filler has dielectric constant not less than 100, dielectric loss not more than 0.05 and particle size D₅₀50-100 nm; and/or the solvent is selected from one or more of dichloromethane, trichloromethane, ethylene glycol dimethyl ether, ethylene glycol dibutyl ether, acetone, butanone, ethyl acetate and xylene; and/or

The first metal film and the second metal film are made of the same or different materials, and are respectively selected from one of copper foil, nickel foil, aluminum foil, silver foil or tin foil, and the thicknesses of the first metal film and the second metal film are respectively 10-50 mu m.

8. A flexible thin film capacitor, prepared by the method according to any one of claims 1 to 7, comprising a first metal film, a second metal film, and a dielectric material layer between the first metal film and the second metal film, wherein: the dielectric material layer comprises an organic polymer matrix and nano inorganic filler uniformly dispersed in the organic polymer matrix, wherein the organic polymer matrix has an interpenetrating polymer network structure.

9. The flexible thin film capacitor of claim 8, wherein: the flexible film capacitor has a dielectric constant change rate of less than 10% with temperature in the use temperature range of 0-80 ℃.

Technical Field

The invention belongs to the technical field of flexible thin film capacitors, and particularly relates to a flexible thin film capacitor capable of being used at a wide temperature range and a preparation method thereof.

Background

The high dielectric material has good functions of storing electric energy and homogenizing an electric field, and has very important application in the industries of electronics, motors and cables. With the rapid development of information, electronics and power industries and the maturation of nanotechnology, the production of polymer-based nanocomposites with high dielectric constant and low dielectric loss at low cost has become a hot point of interest for the industry. The polymer-based composite material filled with the high-dielectric ceramic particles can simultaneously have the excellent performances of high dielectric constant, low dielectric loss, easy processing and the like, and becomes a trend for preparing high-dielectric-constant and low-loss materials.

However, the dielectric constant of this material greatly changes with temperature, and in the use temperature range of 0 to 80 ℃, the dielectric constant gradually increases with the increase of the use temperature, and usually deviates from the initial value by 20 to 30%. Such a large change in dielectric constant can cause a large change in capacitance of the embedded component, thereby greatly affecting the performance of the product.

In view of the above, it is desirable to provide a flexible thin film capacitor that can be used at a wide temperature range, and improve the problem of the dielectric constant of the product varying with temperature.

Disclosure of Invention

In order to solve the problems, the invention provides a flexible thin film capacitor capable of being used at a wide temperature range and a preparation method thereof for the first time starting from an organic polymer matrix material of the flexible thin film capacitor.

The invention provides a preparation method of a flexible thin film capacitor, which comprises the following steps: firstly, preparing a dispersion liquid, wherein the dispersion liquid comprises a first monomer, a curing agent, a second monomer, an initiator, a nano inorganic filler and a solvent; then, coating the dispersion liquid on the surface of a first metal film, drying at low temperature to remove the solvent, and forming a dielectric material precursor layer on the surface of the first metal film; then, covering a second metal film on the surface of the dielectric material precursor layer far away from the first metal film to form a film capacitor precursor; and heating and curing the film capacitor precursor to enable the first monomer to perform in-situ polymerization reaction under the action of the curing agent and the second monomer to perform in-situ polymerization reaction under the action of the initiator respectively to form a dielectric material layer with an interpenetrating polymer network, so that the flexible film capacitor is prepared.

According to one embodiment of the invention, the preparation of the dispersion comprises the steps of: uniformly mixing 10-30 wt% of a first monomer, 10-30 wt% of a second monomer, 0.5-5 wt% of a curing agent, 0.01-5 wt% of an initiator, 40-60 wt% of an inorganic filler and the balance of a solvent to obtain the dispersion, wherein the sum of the mass percentages of the components is 100 wt%.

Further, the step of preparing the dispersion liquid and uniformly mixing comprises grinding; preferably, the grinding is performed on a grinder, and the grinding is performed 4 to 6 times at a rotation speed of 1000 to 2000 rpm.

In the present invention, the first monomer undergoes addition polymerization, polycondensation reaction or ring-opening polymerization reaction only under the action of the curing agent; the first monomer is selected from one or more of epoxy resin, polyurethane, reactive organosilicon and cyclic monomer; and/or the curing agent is selected from one or more of epoxy curing agent, polyurethane curing agent, organic silicon polyol and ring-opening polymerization initiator.

In the present invention, the second monomer is free-radically polymerized only by the initiator; the second monomer is selected from one or more of acrylic acid monomer, acrylic acid prepolymer, styrene and unsaturated polyester; and/or the initiator is a free radical initiator and is selected from one or more of organic amine, acid anhydride, imidazole and derivatives thereof, peroxide, isonitrile acid prepolymer and organic metal compounds.

According to one embodiment of the invention, the low-temperature drying step is drying at 40-60 ℃ for 10-20 minutes; and/or the heating curing step is curing at 100-150 ℃ for 0.5-5 hours.

According to one embodiment of the present invention, the nano inorganic filler is selected from one or more of barium sodium titanate, barium titanate, copper calcium titanate, strontium titanate, barium strontium titanate, calcium titanate, barium calcium titanate, lead zirconate titanate, lead sodium titanate, lead titanate; and/or the nano inorganic filler has a dielectric constant of more than or equal to 100, a dielectric loss of less than or equal to 0.05 and a particle size D₅₀50-100 nm; and/or the solvent is selected from one or more of dichloromethane, trichloromethane, ethylene glycol dimethyl ether, ethylene glycol dibutyl ether, acetone, butanone, ethyl acetate and xylene; and/or the first metal film and the second metal film are made of the same or different materials, and are respectively selected from one of copper foil, nickel foil, aluminum foil, silver foil or tin foil, and the thicknesses of the first metal film and the second metal film are respectively 10-50 mu m.

The invention also provides a flexible film capacitor prepared by the preparation method, which comprises a first metal film, a second metal film and a dielectric material layer positioned between the first metal film and the second metal film, wherein the dielectric material layer comprises an organic polymer matrix and nano inorganic filler uniformly dispersed in the organic polymer matrix, and the organic polymer matrix has an interpenetrating polymer network structure. The flexible film capacitor has a dielectric constant change rate of less than 10% with temperature in the use temperature range of 0-80 ℃.

In the invention, an interpenetrating network polymer structure is formed on the dielectric material layer, the problem of overlarge change of the dielectric constant of the dielectric material layer within the use temperature range of 0-80 ℃ is solved by widening the glass transition temperature of the polymer, and the change rate of the dielectric constant of the dielectric material layer along with the temperature within the use temperature range is effectively controlled within 10 percent.

The foregoing description is only an overview of the technical solutions of the present invention, and in order to make the technical means of the present invention more clearly understood, the present invention may be implemented in accordance with the content of the description, and in order to make the above and other objects, features, and advantages of the present invention more clearly understandable, the following specific preferred embodiments are described in detail.

Detailed Description

To further illustrate the technical means and effects of the present invention adopted to achieve the predetermined objects, the present invention will be described in detail with reference to the following embodiments. It is to be understood that the following examples are illustrative of the invention only and are not limiting thereof.

The invention provides a preparation method of a flexible thin film capacitor capable of being used at a wide temperature, which comprises the following steps: firstly, preparing a dispersion liquid, wherein the dispersion liquid comprises a first monomer, a curing agent, a second monomer, an initiator, a nano inorganic filler and a solvent. And then coating the dispersion liquid on the surface of a first metal film, drying at low temperature to remove the solvent, and forming a dielectric material precursor layer on the surface of the first metal film. And then, covering a second metal film on the surface of the dielectric material precursor layer far away from the first metal film to form a film capacitor precursor. And finally, heating and curing the film capacitor precursor to form a dielectric material layer with an interpenetrating polymer network on the dielectric material precursor layer, thereby preparing the flexible film capacitor. Wherein the first monomer undergoes addition polymerization, polycondensation reaction or ring-opening polymerization reaction only under the action of the curing agent; the second monomer is free-radically polymerized only by the initiator.

In the above preparation method, the preparation of the dispersion liquid specifically includes the steps of: uniformly mixing 10-30 wt% of first monomer, 10-30 wt% of second monomer, 0.5-30 wt% of curing agent, 0.01-5 wt% of initiator, 40-60 wt% of inorganic filler and the balance of solvent to prepare the dispersion. The sum of the mass percentages of the components is 100 wt%.

The first monomer reacts only under the action of the curing agent and does not act on the initiator; the reaction type between the first monomer and the curing agent is addition polymerization, polycondensation reaction and ring-opening polymerization. The first monomer is selected from one or more of the following: epoxy resin prepolymer, polyurethane, reactive silicone and cyclic monomer. The curing agent is selected from one or more of the following substances: epoxy curing agent, polyurethane curing agent, organic silicon polyol and ring-opening polymerization initiator.

Epoxy resins generally refer to organic compounds containing two or more epoxy groups in the molecular structure. The epoxy groups in the molecular chain may be located at the ends of the molecular chain, in the middle of the molecular chain, or in a ring structure. Because the molecular structure contains active epoxy groups, the epoxy groups can generate cross-linking reaction with various curing agents to form insoluble high polymers with a three-dimensional network structure. In one embodiment of the present invention, the epoxy resin is one or more of bisphenol a type epoxy resin, bisphenol F type epoxy resin, novolac type epoxy resin, and glycidyl ether type epoxy resin.

In one embodiment, a reactive polyamide is used for the epoxy resin curing agent. The epoxy curing agent is polyamide which is prepared by the reaction of aliphatic diacid and aliphatic diamine. In one embodiment, the polyamide resin is one or more of polyamide resin 250, polyamide resin 300, polyamide resin 600, and polyamide resin 651.

The cyclic monomer refers to a cyclic compound which can be converted into macromolecules by ring-opening polymerization under the action of an initiator or a catalyst, such as cycloparaffin, cyclic ether, cyclic amine naphthenate, cyclic acetal, cyclic siloxane and cyclic sulfide.

The second monomer is free-radically polymerized only by the initiator, to which the curing agent does not act. The initiator is a free radical initiator. The second monomer is selected from acrylic monomers, acrylic prepolymers, styrene, unsaturated polyesters. The initiator is a free radical initiator and is selected from one or more of organic amine, acid anhydride, imidazole and derivatives thereof, peroxide, isonitrile acid prepolymer and organic metal compounds.

The dielectric constant of the nano inorganic filler is more than or equal to 100, and the dielectric loss is less than or equal to 0.05. In one embodiment, the nano inorganic filler is selected from one or more of the following: sodium barium titanate, calcium copper titanate, strontium barium titanate, calcium titanate,Barium calcium titanate, lead zirconate titanate, sodium lead titanate, and lead titanate. The particle diameter D of the nano inorganic filler₅₀＝50～100nm。

The solvent is selected from one or more of dichloromethane, trichloromethane, ethylene glycol dimethyl ether, ethylene glycol dibutyl ether, acetone, butanone, ethyl acetate and xylene. The solvent can dissolve both the first monomer and the second monomer.

Optionally, in one embodiment, after mixing uniformly, a grinding process is performed. In one embodiment, the grinding process is performed in a grinder at a rotation speed of 1000-2000 rpm for 4-6 times.

In one embodiment, the low-temperature drying temperature is 40-60 ℃ and the time is 10-20 minutes. This drying step removes only the solvent and no polymerization of the monomers occurs. The temperature control of the desolventizing agent is more critical, the formed film can be curled when the temperature is slightly high, and the polymerization reaction of the prepolymer monomer can be easily caused when the temperature is higher; too low a temperature can result in non-uniform composition throughout the film due to evaporation of the solvent for too long a period of time.

The first metal film and the second metal film are selected from one of the following substances: one of copper foil, nickel foil, aluminum foil, silver foil and tin foil. In one embodiment, the first metal film and the second metal film are made of the same material; in another embodiment, the first metal film and the second metal film are made of different materials. The thickness of the first metal film and the second metal film is 10 to 50 μm. The thickness of the resulting dielectric material precursor layer is 3-20 μm.

In the above preparation method, in an embodiment, the step of heating and curing the thin-film capacitor precursor is specifically performed by placing the thin-film capacitor precursor into an oven, and the heating and curing conditions are that the thin-film capacitor precursor is cured at 100-150 ℃ for 0.5-5 hours.

The interpenetrating polymer network structure is formed by respectively carrying out in-situ polymerization reaction on a first monomer under the action of a curing agent and a second monomer under the action of an initiator in the heating and curing process of the dielectric material precursor layer.

In the invention, in the heating and curing process, the first monomer and the second monomer are respectively subjected to in-situ polymerization reaction, so that the dielectric material precursor layer is cured into the dielectric material layer, and the dielectric material layer has an interpenetrating polymer network. In the invention, the first monomer and the second monomer are uniformly dispersed in the dispersion liquid, so that during heating and curing, the first monomer is subjected to in-situ polymerization under the action of a curing agent, and the second monomer is subjected to in-situ polymerization under the action of an initiator and interpenetrated polymerization, thereby forming an interpenetrating polymer network structure.

The invention also provides a flexible thin film capacitor formed by the preparation method and capable of being used at wide temperature, which comprises the following components: the device comprises a first metal film, a second metal film and a dielectric material layer positioned between the first metal film and the second metal film; the dielectric material layer comprises an organic polymer matrix and nano inorganic filler uniformly dispersed in the organic polymer matrix, wherein the organic polymer matrix has an interpenetrating polymer network structure.

In the present invention, the inventor found out the root cause of the change of the dielectric constant of the polymer matrix material with the temperature change is: the dielectric constant of the organic polymer matrix is related to the polarization motion of a specific group, while the amplitude of the polarization motion of the group in a common use temperature range (such as 0-100 ℃) is related to the motion range of a high molecular chain segment, and the motion range of the high molecular chain segment is determined by the glass transition temperature (T)_g) And (6) determining. The problem that the dielectric constant of a polymer matrix material is changed too much along with the temperature is solved by expanding the motion range of the polymer chain segment. The motion range of the polymer chain segment is expanded by selecting two polymer monomers to be fully mixed in a dielectric material precursor layer, and the two polymers are interpenetrated and blended in the polymerization process during heating and curing to form a synchronous network interpenetrating polymer, so that the glass transition temperature of the organic polymer matrix is expanded.

On the other hand, the dielectric constant of the material is greatly dependent on the number of polar groups in the polymerThe polar groups have the directional arrangement capacity under the action of an external electric field. The smaller the intermolecular force of the polymer is, the smaller the resistance to the orientation arrangement is, the easier the orientation arrangement is carried out with the electric field, and the higher the dielectric constant is. The intermolecular force changes greatly around the glass transition temperature, below T_gThe time-sharing subchain is in a frozen state, and the intermolecular acting force is large; higher than T_gThe time-division strand begins to move, at which time the intermolecular forces begin to diminish.

For a single component polymer composite, due to the glass transition temperature T_gIn the temperature range of use, the dielectric constant of the material can change greatly along with the temperature change in the use process. In contrast, for the two-component polymer of the present invention, the T of the polymer constituting the dielectric material layer is formed by an interpenetrating network blending (IPN) technique_gThe range of the use temperature is widened to cover, and the fluctuation of the dielectric constant caused by different resistances to the movement of the polar groups is avoided. Therefore, the IPN interpenetrating network blending technology can improve the problem that the dielectric constant of the organic polymer matrix material changes along with the temperature, and improve the dielectric constant stability of the composite material.

Under an electron microscope, the two polymers constituting the interpenetrating network in the dielectric material layer both exist in their respective phases and are each a continuous phase, thereby forming a complex "cell" structure, the "cell" wall and the "cell" interior being respectively constituted by the two polymers, and a smaller microstructure also existing inside the "cell" wall and the "cell" which is also caused by the interpenetration of the network. With the interpenetrating network polymer of this structure, the glass transition regions of the two phases are shifted and significantly broadened, thereby making the dielectric constant of the dielectric material layer substantially constant over a wide temperature range.

The present invention will be described in further detail with reference to examples. It is also to be understood that the following examples are illustrative of the present invention and are not to be construed as limiting the scope of the invention, and that certain insubstantial modifications and adaptations of the invention by those skilled in the art may be made in light of the above teachings.The specific process parameters and the like of the following examples are also only one example of suitable ranges, i.e., those skilled in the art can select the appropriate ranges through the description herein, and are not limited to the specific values exemplified below. In the following examples and comparative examples, the particle size D of the selected nano inorganic filler (also called high dielectric constant ceramic material) is not particularly specified₅₀＝50～100nm。