Production method of soft polyimide foam

Abstract

The invention provides a production method of soft polyimide foam, comprising the following steps: adding one or more than two kinds of aromatic dianhydride in polar solvent to be totally dissolved; then, adding aromatic diamine to generate amic acid; after reaction, adding two or more than two kinds of foaming agents, and adding one or more than two catalysts and surfactants; at room temperature, mixing the mixture with water and one or more than two kinds of aromatic isocyanate, and foaming; and finally, ripening generated foam in a microwave oven and a high temperature furnace. The polyimide foam obtained by the invention is soft, has elasticity and has favorable sound absorption performance and fire resistance; and the foam density is 4.0-8.0 kg / m3; foam stops firing when foam is far away from fire, so that the amount of emitted smog is small, and no drippage objects exist. Meanwhile, the polyimide foam of the invention has favorable thermal insulation property. The polyimide foam of the invention can be suitable for the fields of aerospace, military ships and the like.

Description

technical field [0001] The invention relates to a production method of polyimide foam, in particular to a production method of soft polyimide foam. Background technique [0002] The materials currently used for thermal insulation are mainly polyurethane foam and phenolic foam. However, polyurethane foam is not flame retardant at all, and produces a large amount of dripping and smoke when burning, with a smoke density of more than 80%; phenolic foam has good flame retardant performance, but the foam has no strength, is easy to pulverize, and the density is too high . However, polyimide foam does not drip when it burns, and its smoke density is only 8%. [0003] Polyimide is a polymer with excellent heat resistance. It has good mechanical and electrical properties, as well as 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 r...

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.

[0005] For example, in US 5,298,531 and 5,122,546,5,077,318, prepolymers are formed first, that is, one or two kinds of dianhydrides are dissolved in polar solvents, and small molecular alcohols such as methanol are added to make them esterified or half-esterified. Then add aromatic or aliphatic diamine to the solution. After the reaction is complete, the small molecules in the initial solution are removed to form a powder, and then the powder is foamed by high temperature to release small molecules such as water and methanol. The main disadvantage is that the drying of the prepolymer is extremely complicated and the density of the foam is too high to produce foams with lower densities

[0006] 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