Preparation method for polyimide film with low water absorption

Abstract

The invention discloses a preparation method for a polyimide film with low water absorption. The preparation method comprises the following steps: under the protection of N2, mixing a diamine monomer A and a dianhydride monomer A in a polar solvent to obtain a flexible polyamide acid resin solution A; under the protection of N2, mixing a diamine monomer B and a dianhydride monomer B in the polar solvent to obtain a rigid polyamide acid resin solution B; under the protection of N2, co-mixing the flexible polyamide acid resin solution A with the rigid polyamide acid resin solution B, stirring, stopping reaction when viscosity of a to-be-reacted matter reaches 2000-3500 poises; and finally, adding an accelerant and a dehydrator to uniformly mix, salivating to form a film, and performing imidization treatment to obtain the polyimide film with the low water absorption. The polyimide film obtained by the preparation method provided by the invention has a water absorption rate lower than 1.2% which is far lower than a water absorption rate (2.3%-2.4%) of conventional polyimide; and meanwhile, excellent comprehensive performance such as mechanical and electrical performance is kept.

Description

technical field [0001] The invention belongs to the field of insulating materials for electric appliances, and in particular relates to a preparation method of a polyimide film with low water absorption. Background technique [0002] Polyimide (PI) film is a key insulating material for electrical appliances, and is widely used in printed circuit boards, power transmission and distribution equipment, wind power generation equipment, frequency conversion motors, high-speed traction motors and high-voltage transformers. [0003] Due to the special molecular structure of PI material, it contains a large number of polar groups, which is easy to absorb water. The water absorption rate of traditional polyimide film is as high as 2.3% to 2.4%, which leads to the explosion and separation of printed circuit boards during the production process. Layer and other quality defects seriously affect the performance and yield of printed circuit boards. In addition, the PI film absorbs water ...

AI Technical Summary

Problems solved by technology

Although the water absorption rate of the polyimide film obtained by this method is significantly reduced, the introduction of fluorine-containing diamine reduces the inherent solvent resistance and other properties of the polyimide film, and the industrial production of fluorine-containing monomers is too difficult, making the industrial production of the film difficult. cost too high

[0005] Patent CN105601923A discloses a fluorine-containing soft-hard block polyimide film and its preparation method and application. Electric constant and low water absorption, but this type of polyimide film also belongs to fluorine-containing polyimide film. In addition to high cost and poor solvent resistance, this method makes the molecular chain structure and film performance It is difficult to control, the production process is complicated, and it is difficult to realize industrial production

[0006] Patent CN101084254B proposes low water-absorbing polyimide and its preparation method, which combines 1,2,4,5-cyclohexanetetracarboxylic acid, the acid dianhydride and their reactive derivatives with compounds selected from Have at least one phenylene and one isopropylidene diamine and the compound in the diisocyanate to react, obtain the polyimide resin of colorless transparency, high heat resistance, low water absorption rate, but the prepared by this method Polyimide film has a water absorption rate of 1.5%, which is still high

[0007] As for the high-performance PI film, there are few mature products in foreign countries at present, and its specific preparation process is still in strict secrecy, and it is still in its infancy in China. Most of them are experimental research conducted by universities and research institutes, and the technology is not yet mature.