A kind of preparation method of polyimide resin and film thereof

Abstract

The present invention relates to the field of polyimide, in particular to a preparation method of polyimide resin, comprising the following steps: S1, after dissolving the first batch of polydiamine in a solvent under an inert gas atmosphere, heat the polyimide at 30°C and In the following low temperature environment, add 105‑110% of the first batch of polyvalent diamine molar total polyvalent dianhydride to polymerize first to form a resin solution, and control the viscosity of the resin solution at 50000‑70000cps; Gradually raise the temperature inside, add the second batch of polydiamines in batches, first more and then less gradually, until the viscosity of the resin solution is 180000-200000cps; S3, add fluorine-containing end-capping agent and mix evenly, and obtain polyimide after high-vacuum defoaming Resin solution, the polyimide coating formed has strong thermal stability, and the thermal expansion coefficient is close to that of the base film.

Description

technical field [0001] The invention relates to the field of polyimide films, in particular to a preparation method of polyimide resin and a film thereof. Background technique [0002] At present, polyamic acid is usually synthesized by low-temperature polycondensation reaction by adding diamine and then dianhydride in a suitable organic solvent in equal moles, and then casting a film on the substrate, and finally thermal imidization to form a film. However, this preparation method makes polyamic acid It is difficult to control the apparent viscosity of amic acid in an ideal demand range with high viscosity, the length of the polymer molecular chain is unbalanced, the viscosity of the resin is difficult to stabilize, and the amount of bubbles in the resin is large. When the molar ratio is equal, the viscosity will show a similar exponential jump. Therefore, it is difficult to control the apparent viscosity of the resin during polymerization in a low-temperature environment b...

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Problems solved by technology

[0002] At present, polyamic acid is usually synthesized by low-temperature polycondensation reaction by adding diamine and then dianhydride in a suitable organic solvent in equal moles, and then casting a film on the substrate, and finally thermal imidization to form a film. However, this preparation method makes polyamic acid It is difficult to control the apparent viscosity of amic acid in an ideal demand range with high viscosity, the length of the polymer molecular chain is unbalanced, the viscosity of the resin is difficult to stabilize, and the amount of bubbles in the resin is large. When the molar ratio is equal, the viscosity will show a similar exponential jump. Therefore, it is difficult to control the apparent viscosity of the resin during polymerization in a low-temperature environment by conventional feeding methods. Often, the viscosity of a very small amount of dianhydride will increase far beyond the expected range, or short-term viscosity at room temperature. Significant decline will bring great difficulties to industrial batch production. Direct addition of diamine solids to control viscosity is prone to local high-level agglomeration and difficult polycondensation, which will reduce the performance and quality of polyimide resin. The film performance thus prepared is also not excellent

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