Method for preparing composite dielectric film

Abstract

The invention discloses a method for preparing a composite dielectric film. According to the method, the film is prepared by mixing fluorine-containing polymer and mixed crystal nanometer TiO2 and casting, wherein the molar ratio of two crystal forms in the mixed crystal nanometer TiO2 can be controlled according to reaction time, anatase accounts for 36 to 45 percent, and rutile accounts for 55 to 64 percent; and the composite dielectric film consists of the following components in percentage by mass: 5 to 40 percent of mixed crystal nanometer TiO2 and 60 to 95 percent of fluorine-containingpolymer. The composite dielectric film is a novel dielectric material with a high dielectric constant and low dielectric loss; the composite dielectric film with the required dielectric constant can be prepared by controlling the addition amount of a filler and the ratio of the filler to the crystal forms; and the composite dielectric film is easy to prepare, low in composite temperature and environment-friendly and has a wide application prospect.

Description

technical field [0001] The invention belongs to the field of preparation of composite dielectric films, in particular to a preparation method of composite dielectric films. Background technique [0002] Polymer-based composite dielectric materials with high dielectric constant, low dielectric loss, and easy processability are functional materials with unique functions and wide applications due to their good flexibility, ability to store charges, and uniform electric field. It has a wide range of applications in the fields of hybrid locomotives, sensors, aerospace military and electric energy storage. Currently, there are three main types of dielectric materials: [0003] 1. Ordinary dielectric ceramic materials: such as copper calcium titanate (CCTO), which has a large capacitance and a dielectric constant of up to 10 4 -10 5 (Lin Zhang, et al., Ferroelectrics.2010, 405, 92.), but the material has a high sintering temperature and is brittle, which affects the machinabilit...

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Problems solved by technology

[0003] 1. Ordinary dielectric ceramic materials: such as copper calcium titanate (CCTO), which has a large capacitance and a dielectric constant of up to 10 4 -10 5 (Lin Zhang, et al., Ferroelectrics.2010, 405, 92.), but the material is sintered at a high temperature, brittle, and the machinability is affected

2. Polymer materials: such as polyvinylidene fluoride (PVDF) has high flexibility and low dielectric loss, but its own dielectric constant is too small (Baojin Chu, et al., science.2006, 313, 334.), severely limit its application

3. Polymer-based composite material with high dielectric properties: conductive titanium carbide (TiC) is used as an additive and filled into PVDF to form a composite material. The dielectric constant of the composite material can reach 540 at 100 Hz (Fajun Wang, et a., Phys .Status Solidi (RRL).2009, 3, 22.), but it is severely limited by the seepage threshold, and the dielectric loss will be greatly increased near the seepage threshold, and it is difficult to control the filling amount

[0004] However, the disadvantage of this method is that the preparation method of most ceramic additive materials is relatively complicated, and its compatibility with polymers is poor, and it is not easy to make thin films.

The ultra-high dielectric constant of most ceramic materials is quite different from that of polymer substrates. When subjected to an external electric field, an inhomogeneous electric field will be generated inside the composite material, which will greatly reduce the compressive strength of the composite material.

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