A kind of preparation method of solvent-resistant porous polyimide film

Abstract

The invention relates to a preparation method of a solvent-resistant porous polyimide thin film. The preparation method comprises the following steps of S1, dispersing an inorganic pore-forming matter coated by a protective agent into a polyamide acid solution, so as to obtain a film forming precursor mixed solution; S2, coating the film forming precursor mixed solution onto the surface of a substrate, drying, performing thermal imidization, and demolding, so as to obtain a polyimide and inorganic pore forming matter composite thin film; S3, soaking the composite thin film into an etching solution, removing forming matter, washing, and drying, so as to obtain the solvent-resistant porous polyimide thin film. The preparation method has the beneficial effects that the inorganic pore-forming matter is coated by the protective agent, then the inorganic pore-forming matter can be quickly and uniformly dispersed into the polyamide acid, the forming of relatively strong hydrogen bonds by the carboxyhydroxyl in the polyamide acid and the oxygen in the inorganic pore-forming matter or the production of trace water by reaction is avoided, the degree of imidization of polyamide acid being converted into polyimide is improved, and the obtained porous thin film has a relatively good mechanical property, high porosity and a good lithium iron-resistant electrolyte property.

Description

technical field [0001] The invention belongs to the field of polymer material preparation, and in particular relates to a preparation method of a solvent-resistant porous polyimide film. Background technique [0002] Polyimide materials have excellent mechanical properties, high temperature resistance, organic chemical corrosion resistance and environmental friendliness, and are widely used in structural materials and functional materials. Among them, the research of porous polyimide materials in filter membranes and battery separators has become a hot spot today. [0003] The preparation methods of porous polyimide film materials include electrospinning film making method, selective corrosion method of polyimide / inorganic pore-forming substance composite film, etc. The selective etching method of polyimide / inorganic pore-forming material composite film to prepare porous polyimide film technology is relatively cheap and simple in process, and the structure and shape of the ...

AI Technical Summary

Problems solved by technology

When metal powders such as nano-aluminum are used as inorganic pore-forming substances, the structure and shape of the micropores of the porous polyimide film can be conveniently controlled through the shape and structure of the nano-materials, and the mechanical properties are also good. However, due to the preparation of nano-metal materials The process is complicated and expensive, and it is not suitable for mass production; relatively speaking, the cost of inorganic pore-forming substances such as nano-calcium carbonate is much lower, and when using inorganic compounds as pore-forming substances, polyamic acid and inorganic pore-forming substances After a long time of dispersion, the porous polyimide film that can be obtained has uniform distribution of nanopores and good microstructure. The material affects the degree of imidization of polyimide, the mechanical properties of the obtained porous polyimide film are not good, and the porous film is brittle

In the prior art, when using inorganic and inorganic pore-forming substances such as calcium carbonate to prepare porous polyimide films, in order to ensure that the material has certain mechanical properties, either only porous films with low porosity can be prepared (for example, CN104910409A, CN104927082A highest porosity Only 18%), or use a multilayer film structure to enhance the mechanical properties of the film. The low porosity of the former limits its usable range, and the latter requires a relatively complicated process to obtain a multilayer film structure, which increases production costs.