Low-apparent-viscosity polyamide acid solution and preparation method thereof

Abstract

The invention discloses a preparation method of a low-apparent-viscosity polyamide acid solution. The preparation method comprises the following specific steps: (1) polymerizing diamine monomers with dianhydride monomers to obtain a polyamide acid solution, adding trimethylchlorosilane with the mass accounting for 5-40wt% of polyamide acid, and stirring at room temperature for 1-5 hours to obtain a polyamide acid solution with the apparent viscosity of 2,000-15,000 centipoises; or (2) polymerizing all the diamine monomers with 60wt%-90wt% of the dianhydride monomers to obtain the polyamide acid solution, adding the trimethylchlorosilane and the rest dianhydride monomers, and stirring at room temperature for 1-5 hours, wherein the molar ratio of the diamine monomers to the dianhydride monomers is 1:1 and the additive amount of the trimethylchlorosilane is 5%-25% of the total mass of the polyamide acid. The invention further provides the low-apparent-viscosity polyamide acid solution prepared by the method. When the polyamide acid solution is prepared by the method (1), the apparent viscosity of the solution is 2,000-15,000 centipoises; when the polyamide acid solution is prepared by the method (2), the apparent viscosity of the solution is 1,000-11,000 centipoises.

Description

technical field [0001] The invention belongs to the technical field of polyimide precursor polyamic acid and its preparation, and in particular relates to a low apparent viscosity polyamic acid solution and a preparation method thereof. Background technique [0002] Polyimide is a kind of polymer characterized by imide ring structure, because of its excellent mechanical properties, thermal properties, dimensional stability, chemical resistance, radiation resistance, low temperature resistance and electrical properties, etc. , are widely used in automobiles, national defense construction, new buildings, microelectronics, separation membranes, medical appliances and nanometers and other fields. Polyimide products come in a variety of forms, including resins, composites, films, fibers, foams, and more. [0003] Polyimide is usually synthesized by a "two-step method", that is, first adding dianhydride and diamine to a polar aprotic solvent for low-temperature polycondensation t...

AI Technical Summary

Problems solved by technology

This method not only has many process steps and complex operation, but more importantly, the degree of reaction in the liquid phase is small, the molecular weight is low, and it is difficult to obtain a higher molecular weight in the later stage of solid phase cross-linking polymerization, so the mechanical strength of the prepared polyimide resin not tall

In addition, although the apparent viscosity of the polyamic acid solution can be reduced to a certain extent by reducing the solid content of the polymer in the polyamic acid solution, the efficiency of this measure to reduce the viscosity is low, and the amount of solvent needs to be greatly increased, thereby increasing production. cost, increase the energy consumption of thermal imidization, and low solid content will significantly reduce production efficiency

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