阅读说明：本技术 一种提高聚丙烯薄膜介电常数的方法 (Method for improving dielectric constant of polypropylene film ) 是由 张晨晨 丁国成 杨海涛 吴兴旺 尹睿涵 朱太云 秦少瑞 胡啸宇 于 2020-06-05 设计创作，主要内容包括：本发明提供了一种提高聚丙烯薄膜介电常数的方法,所述的方法包括将高介电常数的复合填充料置于通入直流电弧等离子体焰流的球化装置中,在表面张力的作用下发生球化,得到平均粒径在95-270nm,平均孔径在350-650nm的球化高介电常数的复合填充料；将所述球化高介电常数的复合填充料在微波辅助作用下进行表面处理以及预分散处理后,添加至制备聚丙烯薄膜的工艺中,在保证聚丙烯薄膜机械性能的前提下,不仅能解决填充料容易发生团聚的问题,还能提高聚丙烯薄膜的介电常数,且介质损耗低,击穿场强大于430KV/mm,在实际的应用中能获得更佳的应用可靠性。(The invention provides a method for improving the dielectric constant of a polypropylene film, which comprises the steps of placing a composite filler with high dielectric constant in a spheroidizing device introduced with direct current arc plasma flame flow, and spheroidizing under the action of surface tension to obtain the spheroidized composite filler with high dielectric constant, wherein the average particle size of the spheroidized composite filler is 95-270nm, and the average pore size of the spheroidized composite filler is 350-650 nm; the spheroidized composite filler with high dielectric constant is subjected to surface treatment and pre-dispersion treatment under the microwave assistance effect, and then is added into the process for preparing the polypropylene film, so that the problem that the filler is easy to agglomerate can be solved, the dielectric constant of the polypropylene film can be improved, the dielectric loss is low, the breakdown field strength is greater than 430KV/mm, and better application reliability can be obtained in practical application on the premise of ensuring the mechanical property of the polypropylene film.)

1. A method for improving the dielectric constant of a polypropylene film is characterized by comprising the following steps: the method comprises the steps of placing the composite filler with high dielectric constant in a spheroidizing device which is introduced with direct current arc plasma flame flow, and spheroidizing under the action of surface tension to obtain the spheroidized composite filler with high dielectric constant, wherein the average particle size of the spheroidized composite filler is 95-270nm, and the average pore diameter of the spheroidized composite filler is 350-650 nm; the spheroidized composite filler with high dielectric constant is subjected to surface treatment and pre-dispersion treatment under the microwave assistance effect, and then is added into the process for preparing the polypropylene film to improve the dielectric constant of the polypropylene film.

2. The method for increasing the dielectric constant of a polypropylene film as claimed in claim 1, wherein: the composite filler with high dielectric constant comprises the following components in a volume ratio of 1-4:1-2: 2-7: 1-4 of ceramic particles, barium titanate, carbon nano tubes and titanium dioxide.

3. The method for increasing the dielectric constant of a polypropylene film as claimed in claim 1, wherein: the conditions of the microwave assistance effect are as follows: the microwave frequency is 1.0-5.0Ghz, and the microwave power is 0.5-2.0 KW.

4. The method for increasing the dielectric constant of a polypropylene film as claimed in claim 1, wherein: the surface treatment comprises the following steps: adding a surface treating agent into the spheroidized composite filler with high dielectric constant, stirring at the stirring speed of 100-250r/min for 10-25min, and standing.

5. The method for increasing the dielectric constant of a polypropylene film as claimed in claim 1, wherein: the pre-dispersion treatment comprises the following steps: magnetically stirring and dispersing for 1-10min at the temperature of 65-90 ℃ and the power of 250-700W.

6. The method for increasing the dielectric constant of a polypropylene film as claimed in claim 1, wherein: the method further comprises the following steps:

s1, adding a coupling agent into the pre-dispersed spheroidized composite filler with high dielectric constant and polypropylene mixed system, and stirring for 1-3h under the condition of ultrasonic oscillation to obtain a fully coupled mixture A;

s2, performing dispersion treatment on the mixture A to obtain a uniformly dispersed mixture B;

and S3, defoaming the mixture B, and placing the mixture B in a vacuum hot press for hot press molding to obtain the polypropylene film.

7. The method as claimed in claim 6, wherein the frequency of the ultrasonic vibration in step S1 is 20-45 Hz.

8. The method for improving the dielectric constant of a polypropylene film as claimed in claim 6, wherein the coupling agent is a 96% by mass solution of 3-aminopropyltriethoxysilane or a 95% by mass solution of (3-mercaptopropyl) trimethoxysilane.

9. The method for improving the dielectric constant of the polypropylene film as claimed in claim 6, wherein the spheroidized composite filler with high dielectric constant and polypropylene in the mixed system comprise the following components in parts by weight: 1-25 parts of spheroidized composite filler with high dielectric constant and 95-140 parts of polypropylene.

Technical Field

The invention relates to the field of material preparation, in particular to a method for improving the dielectric constant of a polypropylene film.

Background

Polymer-based composite dielectric materials have received attention from researchers because of their good mechanical, processing, and insulating properties. At present, polymer matrix composite dielectric materials mainly add high dielectric ceramic materials to polymer bodies. However, the method has the defects that the dielectric constant of the composite material is slowly increased along with the increase of the filling amount of the ceramic material, the mechanical property of the composite material is easily damaged when the filling amount of the ceramic material is too high, the dielectric constant of the obtained polypropylene film is not very high, and in addition, the addition of some nano particles often has higher surface energy and is easy to agglomerate in a system to form a conductive channel, so that the dielectric property of the polypropylene film is lost, and the reliability of the polypropylene film in practical application is greatly limited.

For example, patent No. CN108794941A provides a high dielectric constant inorganic/organic composite material film and a preparation method thereof, which belong to the field of high dielectric films and preparation methods thereof, and the film with extremely high dielectric constant at low frequency is prepared. For another example, patent No. CN104985896B discloses a ceramic-polymer composite material with high dielectric constant and a preparation method thereof, which can prepare a material with improved dielectric constant and reduced dielectric loss. However, the above solution still cannot solve the problem of easy agglomeration of the filling material in the prior art.

In summary, in the field of increasing the dielectric constant of polypropylene films, the above unsolved technical problems exist at all, and the development of new composite fillers and the preparation of polypropylene films with higher dielectric constant are also important approaches for solving the use limitations thereof.

Disclosure of Invention

The invention provides a method for improving the dielectric constant of a polypropylene film, which aims to solve the problems that in the prior art, high-dielectric-constant filler is added into the polypropylene film and is easy to agglomerate, and the added filler in the prior art cannot obviously improve the dielectric constant of the polypropylene film, so that the reliability of the polypropylene film is low in practical application.

In order to achieve the purpose, the invention adopts the following technical scheme:

a method for improving the dielectric constant of a polypropylene film comprises the steps of placing composite filler with high dielectric constant in a spheroidizing device which is introduced with direct current arc plasma flame flow, and spheroidizing under the action of surface tension to obtain the spheroidized composite filler with high dielectric constant, wherein the average particle diameter of the spheroidized composite filler is 95-270nm, and the average pore diameter of the spheroidized composite filler is 350-650 nm; the spheroidized composite filler with high dielectric constant is subjected to surface treatment and pre-dispersion treatment under the microwave assistance effect, and then is added into the process for preparing the polypropylene film to improve the dielectric constant of the polypropylene film.

Optionally, the high dielectric constant composite filler comprises, by volume, 1-4:1-2: 2-7: 1-4 ceramic particles, barium titanate, carbon nano tubes and titanium dioxide.

Optionally, the conditions of the microwave assistance are: the microwave frequency is 1.0-5.0Ghz, and the microwave power is 0.5-2.0 KW.

Optionally, the surface treatment is: adding a surface treating agent into the spheroidized composite filler with high dielectric constant, stirring at the stirring speed of 100-250r/min for 10-25min, and standing.

Optionally, the pre-dispersion processing is: magnetically stirring and dispersing for 1-10min at the temperature of 65-90 ℃ and the power of 250-700W.

In addition, the method of the invention also comprises the following steps:

s1, adding a coupling agent into the pre-dispersed spheroidized composite filler with high dielectric constant and polypropylene mixed system, and stirring for 1-3h under the condition of ultrasonic oscillation to obtain a fully coupled mixture A;

s2, performing dispersion treatment on the mixture A to obtain a uniformly dispersed mixture B;

and S3, defoaming the mixture B, and placing the mixture B in a vacuum hot press for hot press molding to obtain the polypropylene film.

Optionally, the frequency of the ultrasonic oscillation in step S1 is 20-45 Hz.

Alternatively, the coupling agent is a 96% by mass solution of 3-aminopropyltriethoxysilane or a 95% by mass solution of (3-mercaptopropyl) trimethoxysilane.

Optionally, in the mixed system, the weight parts of the composite filler with a high dielectric constant and the polypropylene are as follows: 1-25 parts of high-dielectric-constant composite filler and 95-140 parts of polypropylene.

Compared with the prior art, the invention has the beneficial technical effects that:

1. the method for improving the dielectric constant of the polypropylene film spheroidizes the composite filler with high dielectric constant, the spheroidized composite filler has a certain aperture, the probability of the composite filler forming a conductive channel in the polypropylene film can be reduced, and then the spheroidized filler with high dielectric constant is subjected to surface treatment and pre-dispersion, so that the interfacial compatibility between the spheroidized composite filler and the polypropylene can be effectively improved, the spheroidized composite filler with high dielectric constant has better dispersibility in the polypropylene, and the problem of agglomeration is avoided.

2. In the method, the agglomeration probability of a mixed system of the spheroidized high-dielectric-constant composite filler and the polypropylene can be further reduced by combining ultrasonic oscillation treatment, and the spheroidized high-dielectric-constant composite filler with the average particle size of 95-270nm and the average pore diameter of 350-650nm obtains more contact area in a system formed by the spheroidized high-dielectric-constant composite filler and the polypropylene, so that the dielectric loss is reduced, and the dielectric constant of the polypropylene film can be further effectively improved.

3. The method adopts the following components in a volume ratio of 1-4:1-2: 2-7: 1-4 ceramic particles, barium titanate, carbon nano tubes and titanium dioxide are used as composite filling materials, the components which are utilized in a composite mode have a synergistic effect, a better interaction force is achieved, the components can be arranged in a polypropylene body to be neat, good lap joints are formed among the components, the dielectric constant of the polypropylene film is improved, and meanwhile the mechanical properties related to the polypropylene film cannot be damaged.

4. The polypropylene film prepared by the method has the advantages of higher dielectric constant, low dielectric loss and breakdown field intensity of more than 430KV/mm, and can obtain better application reliability in practical application.

Drawings

The invention will be further understood from the following description in conjunction with the accompanying drawings.

FIG. 1 is a schematic flow chart of a method for increasing the dielectric constant of a polypropylene film according to one embodiment of the present invention;

FIG. 2 is a schematic view of an electron microscope for improving the scanning of a polypropylene film during the preparation process in one embodiment of the present invention;

FIG. 3 is a schematic diagram of an electron microscope for scanning the enhanced polypropylene film in comparative example 2 of the present invention during the preparation process;

FIG. 4 is a schematic view of a surface electron microscope for scanning an enhanced polypropylene film in comparative example 4 of the present invention after the preparation;

fig. 5 is a partially enlarged view of fig. 4.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.

The present invention is a method for increasing the dielectric constant of a polypropylene film, which comprises the following steps according to the embodiments shown in FIGS. 1 to 5: