Preparation and application methods of small-grain-size polyimide powder

Abstract

The invention provides a preparation method of a small-grain-size polyimide powder. The preparation method of the small-grain-size polyimide powder comprises the following steps of dissolving diamineinto organic solvent, then adding in dianhydride for reaction for 3-7 hours, then adding in water separating agent, increasing the temperature to 140-160 DEG C, inletting and mixing in inert gas for dewatering for 6-12 hours, cooling down to 70-90 DEG C, pouring the hot reaction liquid into separated solution, cooling down to 0-35 DEG C for crystallization, and performing filtering and drying to obtain the small-grain-size polyimide powder. The preparation method of the small-grain-size polyimide powder has the advantage that the fine powder is directly obtained after reaction is completed, sothat crushing and screening can be saved, granularity can be uniform, production devices can be simplified, the problem of feeding difficulty during processing can be solved, and industrial values can be achieved. The prepared small-grain-size polyimide powder can be fed into a double-screw extruder for extrusion pelletizing to obtain polyimide granules, which are then injection-molded into standard mechanical testing sample bars for standard mechanical testing, thereby improving the overall mechanical performance.

Description

technical field [0001] The invention relates to a preparation method and application of small-diameter polyimide powder. Background technique [0002] Polyimide is a kind of high-performance polymer containing aromatic ring and imide ring repeating unit structure, which has good mechanical properties and thermal stability. After decades of development, polyimide has developed into a class of high-performance materials with a wide range of products and products, and has always been the focus of research and development in various countries. Especially for its excellent heat resistance and oxidation stability, outstanding mechanical properties at high temperature, radiation resistance and good chemical and physical stability, it has been widely used in many fields such as aerospace, weaponry, automobiles and electronic appliances. application. [0003] The existing polyimide two-step synthesis method is a commonly used method in industrialization now. Add toluene or xylene t...

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Problems solved by technology

[0003] The existing polyimide two-step synthesis method is a commonly used method in industrialization now. Add toluene or xylene to separate water or add acetic anhydride and triethylamine to chemically dehydrate, then precipitate in methanol, ethanol or other solvents, and filter to obtain Polyimide resin, but the polyimide resin obtained by this method is often in the form of flakes or strips, and the particles are not uniform. It needs to be mechanically crushed, sieved and other processes in the later stage to obtain powdered polyimide. Even if the bulk density of the powder obtained in this way is small, the powder is relatively foamy, which makes it difficult to cut the material in the later processing

CN103261277A, CN101253223A disclose the preparation method of polyimide particle, this method needs special ultrasonic equipment, and needs modifier to prepare, and cost is higher, and process is complicated

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