CN117511208A - Polyetherimide-based composite dielectric film material and preparation method thereof - Google Patents

Abstract

The invention discloses a polyetherimide-based composite dielectric film material and a preparation method thereof, wherein the raw materials comprise PEI resin and nano barium titanate subjected to surface treatment, and the surface treatment steps of the nano barium titanate are as follows: treating nano barium titanate with hydrogen peroxide solution to obtain hydroxylated barium titanate; reacting the hydroxylated barium titanate with an epoxy silane coupling agent to obtain epoxidized barium titanate; reacting the epoxidized barium titanate with pentafluorophenol to obtain pentafluorophenol-modified barium titanate; reacting pentafluorophenol modified barium titanate with an aminosilane coupling agent to obtain aminated barium titanate; the aminated barium titanate and 4, 4-diaminodiphenyl ether and pyromellitic anhydride are copolymerized. In the invention, after the pentafluorophenol is modified on the surface of nano barium titanate, the nano barium titanate is polymerized with 4, 4-diaminodiphenyl ether and pyromellitic anhydride in situ to obtain the polyamide acid coated barium titanate, so that the dielectric property and the high-temperature energy storage property of the composite dielectric film material can be effectively improved.

Description

A polyetherimide-based composite dielectric film material and its preparation method

Technical field

The present invention relates to the technical field of dielectric materials, and in particular to a polyetherimide-based composite dielectric film material and a preparation method thereof.

Background technique

Film capacitors are an important basic electronic component. Compared with ceramic capacitors and aluminum/tantalum capacitors, film capacitors have excellent characteristics such as high insulation resistance, high withstand voltage, low dielectric loss, excellent frequency characteristics, and self-healing properties. Currently, the most commonly used film dielectric in film capacitors is BOPP. Its temperature resistance is around 105°C and its relative dielectric constant is only 2-3. Therefore, its energy storage density is less than 2J/cm ³ even under high field strength. , which means that a large volume is required to meet certain energy storage requirements.

Polyetherimide (PEI) is a slightly amber transparent or translucent polymer that can be used for a long time at 150°C. It has good thermal stability, hydrolysis resistance, good dimensional stability, and small molding shrinkage. It can maintain excellent mechanical properties at high temperatures and has excellent electrical properties over a wide temperature and frequency range. It is one of the most potential high-temperature resistant dielectric film polymers. However, the relative dielectric constant of simple polyetherimide materials is low. Generally, high dielectric constant ceramic fillers are added to polyetherimide to increase the dielectric constant of composite materials. Ferroelectric ceramic barium titanate has the characteristics of high dielectric constant, high energy density and excellent stability. Adding it to polyetherimide can effectively improve the dielectric constant of composite materials. For example, "a barium titanate/polyetherimide dielectric composite material and its preparation method" disclosed in Chinese patent documents, its publication number CN112280297A, this invention prepared a material with high breakdown strength (>62) and low-loss (<0.14) dielectric composite materials, and the dielectric properties of the dielectric composite materials can be easily controlled by adjusting the stack thickness.

However, when ceramic particles are combined with a polymer matrix in the existing technology, a larger amount of ceramic particles is generally required to make the composite material have a higher dielectric constant and better high-temperature energy storage performance. However, barium titanate nanoparticles Adding too much will cause the nanoparticles to agglomerate together due to the strong force, which will not only fail to improve the dielectric constant and reduce the dielectric loss, but will also greatly affect the toughness and processing performance of the composite material. It is not conducive to its application in film capacitors.

Contents of the invention

The present invention is to overcome the above-mentioned problems existing in polyetherimide/barium titanate composite dielectric film materials in the prior art, and provides a polyetherimide-based composite dielectric film material and a preparation method thereof. The electroceramic material nanometer barium titanate is used as a filler. After modifying pentafluorophenol on its surface, it is then in-situ polymerized with 4,4-diaminodiphenyl ether and pyromellitic anhydride to obtain polyamic acid-coated barium titanate. Effectively improve the dielectric properties and high-temperature energy storage properties of composite dielectric film materials.

In order to achieve the above objects, the present invention adopts the following technical solutions:

A polyetherimide-based composite dielectric film material. The raw materials include PEI resin with a mass ratio of 100:5~75 and surface-treated nano-barium titanate. The surface treatment steps of the nano-barium titanate are:

A) Treat nanometer barium titanate with hydrogen peroxide solution to obtain hydroxylated barium titanate;

B) React hydroxylated barium titanate with an epoxy silane coupling agent to obtain epoxidized barium titanate;

C) React epoxidized barium titanate with pentafluorophenol to obtain pentafluorophenol-modified barium titanate;

D) React pentafluorophenol-modified barium titanate with an aminosilane coupling agent to obtain aminated barium titanate;

E) Add aminated barium titanate and 4,4-diaminodiphenyl ether into an organic solvent, disperse and stir ultrasonically, then add pyromellitic anhydride, and react to obtain a polyamic acid-coated barium titanate glue solution. The glue solution is centrifuged and filtered to obtain surface-treated nanometer barium titanate.

In order to improve the dispersion and compatibility of nano-barium titanate in PEI resin and improve the performance at the interface between inorganic barium titanate and organic polymers, the present invention modifies pentafluorophenol on the surface of barium titanate and adds it to the titanium surface. Amino groups are introduced onto the surface of barium acid, and then pentafluorophenol-modified barium titanate is polymerized in situ with 4,4-diaminodiphenyl ether and pyromellitic anhydride to obtain polyamic acid-coated barium titanate. Coating polyamic acid on the surface of barium titanate through in-situ polymerization and adding it to the PEI matrix can effectively improve the dispersion and compatibility of barium titanate in the PEI matrix, significantly reduce interface defects, and reduce the film material's Dielectric loss. At the same time, after modifying pentafluorophenol on the surface of barium titanate, because the benzene ring in pentafluorophenol is negatively charged and the benzene ring in polyamic acid is positively charged, through the weak attraction between molecules, the benzene ring in pentafluorophenol is It can generate electrostatic force with the benzene ring in the polyamic acid, optimize the interface properties between the inorganic barium titanate particles and the surface organic polyamic acid, enhance the binding force at the interface, and further reduce the dielectric loss of the film material; Moreover, the benzene ring structure in pentafluorophenol can effectively hinder the transmission of carriers within the polymer at high temperatures, thereby effectively increasing the energy storage density of composite thin film materials at high temperatures.

When the present invention performs surface treatment on barium titanate, it first introduces hydroxyl groups on the surface of nano-barium titanate through step A), and then through step B), utilizing the reaction of the epoxy silane coupling agent and the hydroxyl groups on the surface of barium titanate, Introduce epoxy groups on the surface of barium titanate; then go through step C) to modify the pentafluorophenol on the surface of nanometer barium titanate through the ring-opening reaction of the phenolic hydroxyl group in pentafluorophenol and the epoxy group; then go through step D ) Use the reaction between the aminosilane coupling agent and the hydroxyl group on the surface of barium titanate to introduce amino groups on the surface of barium titanate; finally, through step E), the aminated barium titanate is reacted with 4,4-diaminodiphenyl ether and benzene. Tetracarboxylic anhydride is polymerized in situ to finally obtain polyamic acid-coated barium titanate.

Preferably, the epoxy silane coupling agent described in step B) is 3-glycidoxypropyltrimethoxysilane, and the mass ratio of hydroxylated barium titanate to the epoxy silane coupling agent is 1 :0.3~0.5; the mass ratio of pentafluorophenol and epoxidized barium titanate in step C) is 0.5~1:1; the aminosilane coupling agent described in step D) is 3-aminopropyltrimethoxy The mass ratio of silane, pentafluorophenol-modified barium titanate and aminosilane coupling agent is 1:1~2; the molar ratio of 4,4-diaminodiphenyl ether and pyromellitic anhydride added in step E) The ratio of the mass of aminated barium titanate to the total mass of 4,4-diaminodiphenyl ether and pyromellitic anhydride is 1:4~6.

As a preferred method, the treatment method in step A) is: add nanometer barium titanate with a particle size of 30 to 500 nm into the hydrogen peroxide solution, disperse it evenly with ultrasonic, react at 95 to 105°C for 2 to 4 hours, and separate the product. After cleaning and drying, hydroxylated barium titanate is obtained.

Preferably, the reaction conditions in step B) are: ultrasonically disperse the hydroxylated barium titanate into water and ethanol, then add an epoxy silane coupling agent, stir and react at 20 to 80°C for 8 to 24 hours, and the product After separation, cleaning and drying, epoxidized barium titanate is obtained.

Preferably, the reaction conditions in step C) are: add pentafluorophenol to a sodium hydroxide solution with a mass concentration of 50~60%, stir and dissolve, then add epoxidized barium titanate under inert gas protection, 60~ The reaction was stirred at 70°C for 1 to 3 hours, and the product was separated, washed, and dried to obtain pentafluorophenol-modified barium titanate.

Preferably, the reaction conditions in step D) are: ultrasonically disperse the pentafluorophenol-modified barium titanate into water and ethanol, then add an aminosilane coupling agent, stir and react at 20~80°C for 8~24h, and the product After separation, cleaning and drying, aminated barium titanate is obtained.

Preferably, the reaction time in step E) is 18~30h.

The invention also provides a method for preparing the above-mentioned polyetherimide-based composite dielectric film material, which includes the following steps:

(1) Add the PEI resin to the organic solvent and dissolve it to obtain a polyetherimide solution;

(2) Add the surface-treated nanobarium titanate into the polyetherimide solution, disperse it ultrasonically, and stir evenly to obtain a composite solution;

(3) Apply the composite solution on the substrate to form a composite film, and then perform imidization treatment after drying;

(4) Place the imidized substrate in deionized water to peel off the composite film, and vacuum-dry the composite film to obtain the polyetherimide-based composite dielectric film material.

Preferably, the mass concentration of the polyetherimide solution in step (1) is 10 to 50%.

Preferably, the ultrasonic power in step (2) is 1000-1800W, and the ultrasonic time is 30-60 minutes.

As a preference, the thickness of the composite solution in step (3) is 30~80 μm; the drying temperature is 30~80°C, the drying time is 2~6h; the temperature of the imidization treatment is 100~300°C, and the imidization treatment temperature is 100~300°C. The processing time is 4~8 hours.

Preferably, the vacuum drying temperature in step (4) is 50 to 100°C, and the vacuum drying time is 1 to 4 hours.

Therefore, the present invention has the following beneficial effects:

(1) Introduce amino groups on the surface of nanometer barium titanate, and then conduct in-situ polymerization with 4,4-diaminodiphenyl ether and pyromellitic anhydride to obtain polyamic acid-coated barium titanate, which is added to the PEI matrix. , can effectively improve the dispersion and compatibility of barium titanate in the PEI matrix, significantly reduce interface defects, and reduce the dielectric loss of composite film materials;

(2) Modifying pentafluorophenol on the surface of nanometer barium titanate can improve the interface properties between inorganic barium titanate and the organic polyamic acid on its surface, thereby further reducing the dielectric loss of the composite film material and improving its high-temperature energy storage performance. .

Detailed ways

The present invention will be further described below in conjunction with specific embodiments.

In the present invention, unless otherwise specified, all equipment and raw materials can be purchased from the market or are commonly used in this industry. The methods in the following examples, unless otherwise specified, are all conventional methods in this field.

In each embodiment of the present invention, nanobarium titanate was purchased from McLean Company, with a particle size of 30-500 nm; Sabic Ultem 1000 was used as the PEI resin.

Example 1:

A method for preparing a polyetherimide-based composite dielectric film material, including the following steps:

(1) Surface treatment of nanometer barium titanate:

A) Add nano-barium titanate into a hydrogen peroxide solution with a concentration of 30wt%. The mass-volume ratio of barium titanate nano-particles to hydrogen peroxide solution is 1g:50mL. After ultrasonic dispersion, reflux the reaction at 100°C for 3 hours. The product is separated, washed, and dried to obtain hydroxylated barium titanate;

B) Ultrasonically disperse the hydroxylated barium titanate into water and ethanol with a volume ratio of 1:9, then add 3-glycidoxypropyltrimethoxysilane, hydroxylated barium titanate and 3-glycidyl The mass ratio of etheroxypropyltrimethoxysilane is 1:0.4, and the reaction is stirred at 60°C for 12 hours. The product is separated, washed, and dried to obtain epoxidized barium titanate;

C) Add pentafluorophenol to a sodium hydroxide solution with a mass concentration of 55%, stir and dissolve, then add epoxidized barium titanate under nitrogen protection. The mass ratio of pentafluorophenol to epoxidized barium titanate is: 0.8:1; Stir the reaction at 65°C for 2 hours, separate, clean and dry the product to obtain pentafluorophenol-modified barium titanate;

D) Add pentafluorophenol-modified barium titanate to a mixed solvent of water and ethanol with a volume ratio of 1:9, then add 3-aminopropyltrimethoxysilane, pentafluorophenol-modified barium titanate and 3- The mass ratio of aminopropyltrimethoxysilane is 1:1.5. After ultrasonic mixing, stir and react at 80°C for 18 hours. The product is separated, washed, and dried to obtain aminated barium titanate;

E) Add aminated barium titanate and 4,4-diaminodiphenyl ether to N,N-dimethylacetamide, disperse with ultrasonic and stir, then add pyromellitic anhydride in batches, add 4, The molar ratio of 4-diaminodiphenyl ether and pyromellitic anhydride is 1.4:1, and the ratio of the mass of aminated barium titanate to the total mass of 4,4-diaminodiphenyl ether and pyromellitic anhydride is 1:5; after 24 hours of reaction, a polyamic acid-coated barium titanate glue solution was obtained. The glue solution was centrifuged and filtered to obtain surface-treated nanometer barium titanate;

(2) Add PEI resin to N,N-dimethylacetamide, heat to 60°C and stir until completely dissolved to obtain a polyetherimide solution with a mass concentration of 20%;

(3) Add the surface-treated nano-barium titanate into the polyetherimide solution. The mass ratio of the surface-treated nano-barium titanate to PEI resin is 10:100. Stir for 30 minutes, and then stir at 1400 power. Ultrasonic for 30 minutes to obtain a uniform composite solution;

(4) Use a dropper to drop the composite solution evenly on the glass substrate, adjust the height of the scraper to 50 μm, and scrape to obtain a uniform composite film; place the glass substrate with the composite film scraped on it in a 50°C vacuum oven for vacuum drying. 2h, then raise the temperature to 80℃ and vacuum dry for 2h, then transfer to a high temperature blast oven for imidization treatment. The treatment process is 120℃/1h+160℃/1h+200℃/1h+240℃/1h+300℃/ 1h;

(5) Take out the glass substrate from the blast oven, place it in deionized water, peel off the composite film after 10 minutes, place it in a vacuum oven, and vacuum dry it at 60°C for 2 hours to obtain the polyetherimide base Composite dielectric film materials.

Example 2:

A method for preparing a polyetherimide-based composite dielectric film material, including the following steps:

(1) Surface treatment of nanometer barium titanate:

A) Add nano-barium titanate into a hydrogen peroxide solution with a concentration of 30wt%. The mass-volume ratio of barium titanate nano-particles to hydrogen peroxide solution is 1g:50mL. After ultrasonic dispersion, reflux the reaction at 95°C for 4 hours. The product is separated, washed, and dried to obtain hydroxylated barium titanate;

B) Ultrasonically disperse the hydroxylated barium titanate into water and ethanol with a volume ratio of 2:8, then add 3-glycidoxypropyltrimethoxysilane, hydroxylated barium titanate and 3-glycidyl The mass ratio of etheroxypropyltrimethoxysilane is 1:0.3, and the reaction is stirred at 25°C for 24 hours. The product is separated, washed, and dried to obtain epoxidized barium titanate;

C) Add pentafluorophenol to a sodium hydroxide solution with a mass concentration of 50%, stir and dissolve, and then add epoxidized barium titanate under nitrogen protection. The mass ratio of pentafluorophenol to epoxidized barium titanate is: 0.5:1; Stir the reaction at 60°C for 3 hours, separate, clean and dry the product to obtain pentafluorophenol-modified barium titanate;

D) Add pentafluorophenol-modified barium titanate to a mixed solvent of water and ethanol with a volume ratio of 2:8, then add 3-aminopropyltrimethoxysilane, pentafluorophenol-modified barium titanate and 3- The mass ratio of aminopropyltrimethoxysilane is 1:1. After ultrasonic mixing, the reaction is stirred for 24 hours at 25°C. The product is separated, washed, and dried to obtain aminated barium titanate;

E) Add aminated barium titanate and 4,4-diaminodiphenyl ether to N,N-dimethylacetamide, disperse with ultrasonic and stir, then add pyromellitic anhydride in batches, add 4, The molar ratio of 4-diaminodiphenyl ether and pyromellitic anhydride is 1.3:1, and the ratio of the mass of aminated barium titanate to the total mass of 4,4-diaminodiphenyl ether and pyromellitic anhydride is 1:4; After reacting for 24 hours, a polyamic acid-coated barium titanate glue solution was obtained. The glue solution was centrifuged and filtered to obtain surface-treated nanometer barium titanate;

(2) Add PEI resin to N,N-dimethylacetamide, heat to 60°C and stir until completely dissolved to obtain a polyetherimide solution with a mass concentration of 20%;

(3) Add the surface-treated nano-barium titanate into the polyetherimide solution. The mass ratio of the surface-treated nano-barium titanate to PEI resin is 20:100. Stir for 30 minutes, and then stir at 1400 power. Ultrasonic for 30 minutes to obtain a uniform composite solution;

(4) Use a dropper to drop the composite solution evenly on the glass substrate, adjust the height of the scraper to 50 μm, and scrape to obtain a uniform composite film; place the glass substrate with the composite film scraped on it in a 50°C vacuum oven for vacuum drying. 2h, then raise the temperature to 80℃ and vacuum dry for 2h, then transfer to a high temperature blast oven for imidization treatment. The treatment process is 120℃/1h+160℃/1h+200℃/1h+240℃/1h+300℃/ 1h;

(5) Take out the glass substrate from the blast oven, place it in deionized water, peel off the composite film after 10 minutes, place it in a vacuum oven, and vacuum dry it at 60°C for 2 hours to obtain the polyetherimide base Composite dielectric film materials.

Example 3:

A method for preparing a polyetherimide-based composite dielectric film material, including the following steps:

(1) Surface treatment of nanometer barium titanate:

A) Add nano-barium titanate into a hydrogen peroxide solution with a concentration of 30wt%. The mass-volume ratio of barium titanate nano-particles to hydrogen peroxide solution is 1g:50mL. After ultrasonic dispersion, reflux the reaction at 105°C for 2 hours. The product is separated, washed, and dried to obtain hydroxylated barium titanate;

B) Ultrasonically disperse the hydroxylated barium titanate into water and ethanol with a volume ratio of 3:7, then add 3-glycidoxypropyltrimethoxysilane, hydroxylated barium titanate and 3-glycidyl The mass ratio of etheroxypropyltrimethoxysilane is 1:0.5, and the reaction is stirred at 80°C for 8 hours. The product is separated, washed, and dried to obtain epoxidized barium titanate;

C) Add pentafluorophenol to a sodium hydroxide solution with a mass concentration of 60%, stir and dissolve, and then add epoxidized barium titanate under nitrogen protection. The mass ratio of pentafluorophenol to epoxidized barium titanate is: 1:1; Stir the reaction at 70°C for 2 hours, separate, clean and dry the product to obtain pentafluorophenol-modified barium titanate;

D) Add pentafluorophenol-modified barium titanate to a mixed solvent of water and ethanol with a volume ratio of 3:7, then add 3-aminopropyltrimethoxysilane, pentafluorophenol-modified barium titanate and 3- The mass ratio of aminopropyltrimethoxysilane is 1:1. After ultrasonic mixing, the reaction is stirred at 80°C for 8 hours. The product is separated, washed, and dried to obtain aminated barium titanate;

E) Add aminated barium titanate and 4,4-diaminodiphenyl ether to N,N-dimethylacetamide, disperse with ultrasonic and stir, then add pyromellitic anhydride in batches, add 4, The molar ratio of 4-diaminodiphenyl ether and pyromellitic anhydride is 1.5:1, and the ratio of the mass of aminated barium titanate to the total mass of 4,4-diaminodiphenyl ether and pyromellitic anhydride is 1:6; After reacting for 24 hours, a polyamic acid-coated barium titanate glue solution was obtained. The glue solution was centrifuged and filtered to obtain surface-treated nanometer barium titanate;

(2) Add PEI resin to N,N-dimethylacetamide, heat to 60°C and stir until completely dissolved to obtain a polyetherimide solution with a mass concentration of 20%;

(3) Add the surface-treated nano-barium titanate into the polyetherimide solution. The mass ratio of the surface-treated nano-barium titanate to PEI resin is 30:100. Stir for 30 minutes, and then stir at 1400 power. Ultrasonic for 30 minutes to obtain a uniform composite solution;

(4) Use a dropper to drop the composite solution evenly on the glass substrate, adjust the height of the scraper to 50 μm, and scrape to obtain a uniform composite film; place the glass substrate with the composite film scraped on it in a 50°C vacuum oven for vacuum drying. 2h, then raise the temperature to 80℃ and vacuum dry for 2h, then transfer to a high temperature blast oven for imidization treatment. The treatment process is 120℃/1h+160℃/1h+200℃/1h+240℃/1h+300℃/ 1h;

(5) Take out the glass substrate from the blast oven, place it in deionized water, peel off the composite film after 10 minutes, place it in a vacuum oven, and vacuum dry it at 60°C for 2 hours to obtain the polyetherimide base Composite dielectric film materials.

Example 4:

In step (3) of Example 4, the mass ratio of the surface-treated nanobarium titanate to the polyetherimide resin is 40:100, and the rest are the same as in Example 1.

Example 5:

In step (3) of Example 5, the mass ratio of the surface-treated nanobarium titanate to the polyetherimide resin is 50:100, and the rest are the same as in Example 1.

Comparative Example 1 (without adding nano-barium titanate):

A method for preparing polyetherimide film material, including the following steps:

(1) Add PEI resin to N,N-dimethylacetamide solvent, heat to 60°C and stir until completely dissolved to obtain a polyetherimide solution with a mass concentration of 20%;

(2) Use a dropper to drop the polyetherimide solution evenly on the glass substrate, adjust the height of the scraper to 50 μm, and scrape to obtain a uniform polyetherimide film; scrape the glass substrate with the polyetherimide film. , first placed in a 40°C vacuum oven for vacuum drying for 4 hours, and then transferred to a 180°C blast oven to dry for 4 hours to remove the organic solvent;

(3) Take out the glass substrate from the blast oven, place it in deionized water, peel off the polyetherimide film after 10 minutes, place it in a vacuum oven, and vacuum dry it at 50°C for 4 hours to obtain the polyether Imide film material.

Comparative Example 2 (nano-barium titanate is directly mixed with PEI resin):

A preparation method of polyetherimide/barium titanate film material, including the following steps:

(1) Add PEI resin to N,N-dimethylacetamide solvent, heat to 60°C and stir until completely dissolved to obtain a polyetherimide solution with a mass concentration of 20%;

(2) Add nano-barium titanate to the polyetherimide solution. The mass ratio of nano-barium titanate to polyetherimide is 10:100. Stir for 30 minutes, and then ultrasonic for 30 minutes at 1400 power to obtain a uniform composite solution. ;

(3) Use a dropper to drop the composite solution evenly on the glass substrate, adjust the height of the scraper to 50 μm, and scrape to obtain a uniform composite film; place the glass substrate with the composite film scraped on it in a 40°C vacuum oven for vacuum drying. 4h, and then transferred to a blast oven at 180°C to dry for 4h to remove the organic solvent;

(4) Take out the glass substrate from the blast oven, place it in deionized water, peel off the composite film after 10 minutes, place it in a vacuum oven, and vacuum dry it at 50°C for 4 hours to obtain the polyetherimide/ Barium titanate composite dielectric film material.

Comparative Example 3 (no pentafluorophenol surface modification on nanobarium titanate):

The difference between Comparative Example 3 and Example 1 is that the surface treatment method of nanobarium titanate in step (1) is:

A) Add nano-barium titanate into a hydrogen peroxide solution with a concentration of 30wt%. The mass-volume ratio of barium titanate nano-particles to hydrogen peroxide solution is 1g:50mL. After ultrasonic dispersion, reflux the reaction at 100°C for 3 hours. The product is separated, washed, and dried to obtain hydroxylated barium titanate;

B) Add hydroxylated barium titanate to a mixed solvent of water and ethanol with a volume ratio of 1:9, then add 3-aminopropyltrimethoxysilane, hydroxylated barium titanate and 3-aminopropyltrimethyl The mass ratio of oxysilane is 1:1.5. After ultrasonic mixing, the reaction is stirred at 80°C for 18 hours. The product is separated, washed, and dried to obtain aminated barium titanate;

C) Add aminated barium titanate and 4,4-diaminodiphenyl ether to N,N-dimethylacetamide, disperse with ultrasonic and stir, then add pyromellitic anhydride in batches, add 4, The molar ratio of 4-diaminodiphenyl ether and pyromellitic anhydride is 1.4:1, and the ratio of the mass of aminated barium titanate to the total mass of 4,4-diaminodiphenyl ether and pyromellitic anhydride is 1:5; after 24 hours of reaction, a polyamic acid-coated barium titanate glue solution was obtained. The glue solution was centrifuged and filtered to obtain surface-treated nanometer barium titanate;

The rest are the same as in Example 1.

Comparative Example 4 (direct mixing of pentafluorophenol):

The difference between Comparative Example 4 and Example 1 is that the surface treatment method of nanobarium titanate in step (1) is:

A) Add nano-barium titanate into a hydrogen peroxide solution with a concentration of 30wt%. The mass-volume ratio of barium titanate nano-particles to hydrogen peroxide solution is 1g:50mL. After ultrasonic dispersion, reflux the reaction at 100°C for 3 hours. The product is separated, washed, and dried to obtain hydroxylated barium titanate;

B) Add hydroxylated barium titanate to a mixed solvent of water and ethanol with a volume ratio of 1:9, then add 3-aminopropyltrimethoxysilane, hydroxylated barium titanate and 3-aminopropyltrimethyl The mass ratio of oxysilane is 1:1.5. After ultrasonic mixing, the reaction is stirred at 80°C for 18 hours. The product is separated, washed, and dried to obtain aminated barium titanate;

C) Add aminated barium titanate, pentafluorophenol and 4,4-diaminodiphenyl ether to N,N-dimethylacetamide, disperse with ultrasonic and stir, then add pyromellitic anhydride in batches, The mass ratio of the added pentafluorophenol to the aminated barium titanate is 0.8:1, the molar ratio of 4,4-diaminodiphenyl ether and pyromellitic anhydride is 1.4:1, and the mass ratio of the aminated barium titanate is The ratio to the total mass of 4,4-diaminodiphenyl ether and pyromellitic anhydride is 1:5; after 24 hours of reaction, the polyamic acid-coated barium titanate glue is obtained. The glue is centrifuged and filtered to obtain the Nano-barium titanate after surface treatment;

The rest are the same as in Example 1.

The dielectric constant and dielectric loss of the thin film materials prepared in the above embodiments and comparative examples were tested, and the polarization curve and energy storage density were tested at a frequency of 10 Hz. The relevant performance test results are shown in Table 1.

Table 1: Film material performance test results

As can be seen from Table 1, in Examples 1 to 5 using the method of the present invention, the dielectric constant and energy storage density of the composite dielectric film material are obtained compared with the pure polyetherimide film in Comparative Example 1. Significantly improved and has lower dielectric loss.

In Comparative Example 2, barium titanate is directly compounded with PEI resin, and the dielectric loss of the composite material increases significantly compared with the example; the reason is that in the example of the present invention, aminated barium titanate is combined with 4,4-diamino In-situ polymerization of diphenyl ether and pyromellitic anhydride allows barium titanate nanoparticles to be directly connected to the polyamic acid molecular chain, achieving molecular level dispersion. At the same time, due to the compatibility of polyamic acid and polyetherimide matrix Excellent dispersion of barium titanate nanoparticles in the final composite film, reducing the dielectric loss of the composite film material, reducing the leakage current of the composite film material, and improving the performance of the composite film material at high temperatures The breakdown field strength significantly improves the energy storage density of composite thin film materials at high temperatures.

In Comparative Example 3, pentafluorophenol was not modified on the surface of nanobarium titanate, and the dielectric loss and energy storage density of the composite material decreased compared with Example 1; in Comparative Example 4, pentafluorophenol was not chemically bonded to The surface of barium titanate is directly blended with aminated barium titanate, 4,4-diaminodiphenyl ether and pyromellitic anhydride during the polymerization process. The energy storage density of the composite material is the same as in Example 1. There has also been a decrease in comparison. It shows that modifying fluorine-free phenol on the surface of barium titanate can improve the interface properties between inorganic particles and their polymer coating layer, thereby helping to further improve the dielectric energy storage performance of composite materials.

Claims (10)

1. The polyetherimide-based composite dielectric film material is characterized by comprising PEI resin and nano barium titanate subjected to surface treatment, wherein the mass ratio of the PEI resin to the nano barium titanate is 100:5-75, and the surface treatment steps of the nano barium titanate are as follows:

a) Treating nano barium titanate with hydrogen peroxide solution to obtain hydroxylated barium titanate;

b) Reacting the hydroxylated barium titanate with an epoxy silane coupling agent to obtain epoxidized barium titanate;

c) Reacting the epoxidized barium titanate with pentafluorophenol to obtain pentafluorophenol-modified barium titanate;

d) Reacting pentafluorophenol modified barium titanate with an aminosilane coupling agent to obtain aminated barium titanate;

e) Adding the aminated barium titanate and 4, 4-diaminodiphenyl ether into an organic solvent, performing ultrasonic dispersion and stirring, adding pyromellitic anhydride, reacting to obtain polyamic acid coated barium titanate glue solution, centrifuging the glue solution, and filtering to obtain the nano barium titanate after surface treatment.

2. The polyetherimide based composite dielectric film material according to claim 1, wherein the epoxy silane coupling agent in the step B) is 3-glycidoxypropyl trimethoxysilane, and the mass ratio of the hydroxylated barium titanate to the epoxy silane coupling agent is 1:0.3-0.5;

the mass ratio of pentafluorophenol to the epoxidized barium titanate in the step C) is 0.5-1:1;

the aminosilane coupling agent in the step D) is 3-aminopropyl trimethoxy silane, and the mass ratio of the pentafluorophenol modified barium titanate to the aminosilane coupling agent is 1:1-2;

the molar ratio of the 4, 4-diaminodiphenyl ether to the pyromellitic anhydride added in the step E) is 1.3-1.5:1, and the ratio of the mass of the aminated barium titanate to the total mass of the 4, 4-diaminodiphenyl ether and the pyromellitic anhydride is 1:4-6.

3. The polyetherimide based composite dielectric film material of claim 1, wherein the processing method in step a) is: adding nano barium titanate with the particle size of 30-500nm into hydrogen peroxide solution, carrying out ultrasonic dispersion uniformly, reacting for 2-4 hours at the temperature of 95-105 ℃, separating, cleaning and drying the product, and thus obtaining the hydroxylated barium titanate.

4. The polyetherimide based composite dielectric film material of claim 1 or 2, wherein the reaction conditions in step B) are: and (3) ultrasonically dispersing the hydroxylated barium titanate into water and ethanol, adding an epoxy silane coupling agent, stirring at 20-80 ℃ for reaction for 8-24 hours, separating, cleaning and drying the product to obtain the epoxidized barium titanate.

5. The polyetherimide based composite dielectric film material of claim 1 or 2, wherein the reaction conditions in step C) are: and adding pentafluorophenol into a sodium hydroxide solution with the mass concentration of 50-60%, stirring and dissolving, adding epoxidized barium titanate under the protection of inert gas, stirring and reacting for 1-3 hours at the temperature of 60-70 ℃, and separating, cleaning and drying the product to obtain the pentafluorophenol modified barium titanate.

6. The polyetherimide based composite dielectric film material of claim 1 or 2, wherein the reaction conditions in step D) are: dispersing the pentafluorophenol modified barium titanate into water and ethanol by ultrasonic, adding an aminosilane coupling agent, stirring at 20-80 ℃ for reaction for 8-24 hours, and separating, cleaning and drying the product to obtain the aminated barium titanate.

7. The polyetherimide based composite dielectric film material of claim 1 or 2, wherein the reaction time in step E) is 18 to 30 hours.

8. A method for preparing the polyetherimide-based composite dielectric film material according to any one of claims 1 to 7, comprising the steps of:

(1) Adding PEI resin into an organic solvent, and dissolving to obtain a polyetherimide solution;

(2) Adding the nano barium titanate subjected to surface treatment into a polyetherimide solution, performing ultrasonic dispersion, and uniformly stirring to obtain a composite solution;

(3) The composite solution is coated on a substrate in a scraping way to form a composite film, and imidization treatment is carried out after drying;

(4) And (3) placing the imidized substrate in deionized water to strip the composite film, and vacuum drying the composite film to obtain the polyetherimide-based composite dielectric film material.

9. The preparation method of claim 8, wherein the mass concentration of the polyetherimide solution in the step (1) is 10-50%.

10. The preparation method of claim 8, wherein the doctor blade thickness of the composite solution in the step (3) is 30-80 μm; the drying temperature is 30-80 ℃ and the drying time is 2-6 hours; the imidization treatment is carried out at a temperature of 100-300 ℃ for 4-8 hours.