Preparation method for thermoplastic polyimide foaming particle and formed body thereof

Abstract

The invention provides a preparation method for a thermoplastic polyimide foaming particle. The preparation method comprises the following steps of: firstly, producing the thermoplastic polyimide particle into a polyimide particle by a melt extrusion method; secondly, feeding the polyimide particle into a high-pressure autoclave, injecting high-pressure mixed fluid consisting of high-pressure fluid such as CO2, N2, HFC and HCFC and organic solves such as tetrahydrofuran, chloroform, ethanol and methanol and enabling the high-pressure mixed fluid to reach a saturated state in the thermoplastic polyimide particle; and finally, heating and foaming the saturated thermoplastic polyimide particle in continuous hot air to obtain the thermoplastic polyimide particle with high expansion degree and a cellular structure in a closed-cell structure. An adhesive solution is uniformly coated on the foaming particle for die pressing and thermal curing to obtain a thermoplastic polyimide foaming particle formed body with low density, controllable shape and size and favorable mechanical property. The preparation method is a preparation method with a favorable application prospect for the polyimide foaming particle.

Description

technical field [0001] The present invention relates to the technical field of preparation of polyimide foaming materials, in particular to a method for preparing thermoplastic polyimide foaming particles, and a method for preparing foamed particle moldings by using the thermoplastic polyimide foaming particles . Background technique [0002] Polyimide foam is widely used in military and civilian fields such as aerospace aircraft, surface ships, submarines, rail transit, etc. due to its light weight, excellent heat insulation performance, high and low temperature resistance, impact resistance, and self-flammability. [0003] A large number of patents at home and abroad disclose the preparation methods of polyimide foam materials, mainly including paste foaming method, powder foaming method and ball foaming method. U.S. Patents US5077318A, US5122546A, etc. disclose a paste foaming method, which uses a high-solid-content polyimide precursor paste for heating and foaming. The...

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Problems solved by technology

[0004] The above-mentioned traditional polyimide foaming material preparation methods all involve the imidization reaction of the polyimide precursor in the foaming process, and the prepared foaming materials mostly have incomplete imidization reaction, foaming material Unstable performance and other issues

More importantly, the polyimide foam materials prepared by traditional methods are prone to powder peeling, which not only damages the health of operators, but also poses safety hazards

Further, lightweight polyimide foam materials often contain a large number of functional particles, and the peeling off of functional particles during construction and use will weaken the functionality of the material.

In addition, the traditional polyimide foam material has the defects of high open cell content and high water absorption, which limits the application range of this material

[0005] The preparation process of traditional polyimide foam materials often requires the use of molds. The size of foam materials is limited by the size of the mold. The preparation process of foam materials is complicated, the production efficiency is low, and the material properties between batches are not easy to control stably.

In order to solve the problem of temperature gradient in the mold during the preparation of thick foam materials and the problem of slow heating rate in large-size molds, researchers often use microwave heating to reduce the temperature gradient of the mold. This method has expensive equipment and production high cost problem

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