Preparation method of polyimide film

Abstract

The invention discloses a preparation method of a polyimide film, which includes steps of S1, dividing benzenetetracarboxylic anhydride into two equal parts; adding two parts to a reaction filled withfluorinated diamine N-methyl pyrrolidon solution from different feeding openings at the same time, and reacting for 3-7 hours, wherein the mole ratio of benzenetetracarboxylic anhydride and fluorinated diamine is 1: 1.05-1.15; S2, adding dewatering agent, and fully stirring at 4-10 DEG C to obtain fluorine-containing polyamide acid solution; S3, coating the fluorine-containing polyamide acid solution on a glass plate; orderly heating for 1 h in an argon oven under the temperatures of 50 DEG C, 250 DEG C, 200 DEG C, 250 DEG C, 300 DEG C and 400 DEG C every time; and preparing the polyimide film. Through wide back ring type heating method, the film is repeatedly heated and cooled so as to ensure that the involatile matter can befully volatilized; the thin film material is free from pore, better in heat resistance and thermal stability, and high in quality.

Description

technical field [0001] The invention relates to the technical field of polymer materials. More particularly, the present invention relates to a kind of preparation method of polyimide film. Background technique [0002] Polyimide has excellent mechanical properties, heat resistance, low temperature resistance, flame retardancy, solvent resistance and electrical properties. It can be used as a structural composite material and is widely used in aerospace, aviation, precision machinery, microelectronic devices and Transparent conductive film, TFT substrate and flexible printed circuit substrate, etc. [0003] Polyimide is usually synthesized in two steps: the first step is the formation of polyamic acid (PAA) by dianhydride and diamine in a polar aprotic reaction solvent; the second step is the thermal imidization of PAA to poly Imide, the following problems mainly exist in the preparation process: the high-boiling-point protic solvent is difficult to volatilize cleanly duri...

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Problems solved by technology

[0003] Polyimide is usually synthesized in two steps: the first step is the formation of polyamic acid (PAA) by dianhydride and diamine in a polar aprotic reaction solvent; the second step is the thermal imidization of PAA to poly Imide, the following problems mainly exist in the preparation process: the high-boiling-point protic solvent is difficult to volatilize cleanly during the preparation process, and volatiles are also emitted during the cyclization (imidization) of polyamic acid, which is easy to produce in composite products. It is difficult to obtain high-quality composite materials without pores; due to the characteristics of rigid chains, polyimide has a high melting temperature and is not easy to process, and the film made of traditional polyimide is generally hard, brittle, The strength is not enough, and there are still defects in the microelectronics industry that reduce the linear expansion coefficient and mechanical strength; due to the formation of intramolecular and intermolecular charge transfer complexes (CTC) and electronic polarization, traditional PI films are often yellow or yellow. Dark brown, cannot meet the requirements of optical waveguide materials in the communication field, alignment films of liquid crystal displays, flexible transparent conductive substrates, etc. for the transparency of PI thin films in the optical field

[0004] At the same time, due to the high price of raw materials, the production cost of polyimide has been high

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