A kind of foaming fluorine-containing polyimide and preparation method thereof

Abstract

The invention discloses a foamed fluorine-containing polyimide and a preparation method of foam thereof, belonging to the field of foamed polyimides and preparation of foam thereof. The preparation method of the foamed fluorine-containing polyimide sequentially comprises the following steps: adding fluorine-containing diamine, fluorine-containing dianhydride and blocking agent which are dissolved in an organic solvent into a reactor; heating the reaction solution, and adding organic alkali while stirring; and dehydrating the reaction solution under reduced pressure. The preparation method of the fluorine-containing polyimide foam comprises the following steps: forming and foaming the fluorine-containing polyimide by microwaves, and curing at normal temperature to prepare the fluorine-containing polyimide foam. The prepared foam precursor solution has favorable storage stability, and is suitable for casting, spray coating, extrusion and other processing techniques. The prepared foam has the advantages of low density, very low hygroscopicity and favorable toughness, and does not need to add any toughening modifier.

Description

technical field [0001] The invention belongs to the field of foamed polyimide and its foam preparation. Background technique [0002] Polyimide is a polymer with excellent heat resistance. It has good mechanical and electrical properties, radiation resistance and corrosion resistance. It is widely used in aerospace, military, electronics and other fields. The polyimide material with foam structure not only maintains the excellent heat resistance and flame retardancy of the original resin, but also has outstanding wave transmission properties, light weight, good flexibility and rebound, and convenient use. Therefore, it is widely used in military equipment has extremely important uses. Compared with the polystyrene foam, polyvinyl chloride foam, polyurethane foam and other materials that dominated the market in the early stage, it has special excellent performance in terms of flame retardancy, its light weight, high rigidity, good dimensional stability, and chemical resistan...

AI Technical Summary

Problems solved by technology

Some soft thermoplastic polyimide foams are made of thermoplastic polyimide powder and foaming agent at high temperature, and the uniformity of the cells and the stability of the process are poor; the high temperature resistance of the foam is also poor.

However, some polyimide foams are obtained by directly using the esterification solution of dianhydride and isocyanate to react and ripen, and the mechanical properties of the foam are poor.

[0004] CN101402795A discloses a novel high-temperature-resistant polyimide foam, which also produces powder prepolymer by esterifying bisanhydrides and adding active diamines in the solution, and produces polyimide foam plastics by two-step method , and the foam is rigid foam with a density of 100-500kg / m 3 , not suitable for low density foam production

[0005] CN101402743A discloses a foam precursor solution formed by mixing aromatic dianhydride and / or aromatic acid ester, low-molecular alcohol, catalyst, and surfactant in a polar solvent in proportion, and the precursor solution reacts with isocyanate in a mold. Free foaming forms a foam intermediate, and then solid polyimide foam is obtained after microwave radiation or / and oven heating and curing. The residual solvent low-molecular alcohol and blowing agent toluene diisocyanate in the reaction reduce the flame retardancy and resistance of the foam. High temperature, high temperature curing energy consumption will increase in the later stage, and the use is limited

[0007] The method of improving the toughness of polyimide foam is generally to add toughening components in the polyimide resin foaming process. Although the addition of various toughening components can improve the toughness of the foam, it reduces the polyimide foam. Flame retardancy and other properties of imide foam

The addition of a large amount of toughening components will also affect the microstructure of the foam, increase the foam opening ratio, pore size, and thermal conductivity, thereby affecting the thermal insulation performance of the foam

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