CN-119060336-B - Hyperbranched polyimide flexible foam and preparation method thereof

Abstract

A hyperbranched polyimide flexible foam and a preparation method thereof comprise the steps of sequentially mixing a first difunctional aromatic dianhydride, an alcohol solvent, an ether solvent and a polar organic solvent, obtaining a first monoacid monoester mixed solution through reflux stirring reaction, sequentially mixing a second difunctional aromatic dianhydride, an alcohol solvent, an ether solvent, a ring-opening catalyst and a polar organic solvent, obtaining a second monoacid monoester mixed solution through reflux stirring reaction, mixing the first monoacid monoester mixed solution obtained in the step 01 and the second monoacid monoester mixed solution obtained in the step 02, adding polyfunctional isocyanate, stirring until gas volatilizes, adding foam stabilizer and deionized water into the mixed solution obtained in the step 03, stirring, and injecting air into the mixed solution obtained in the step 04 to obtain the hyperbranched polyimide flexible foam.

Inventors

• LIU LIHUI
• LIU YINGXI
• LI YINGDE
• Yu Xutian
• HUANG YONG
• LUO JIYONG

Assignees

• 自贡中天胜新材料科技有限公司

Dates

Publication Date

20260505

Application Date

20241012

Claims (1)

1. 1. A preparation method of hyperbranched polyimide flexible foam comprises the following steps: Step 01, adding 322.2g of 3,3', 4' -benzophenone tetracarboxylic dianhydride, 46.0g of ethanol, 1288.8g of tetrahydrofuran, 322.2g of N, N-dimethylformamide and 3.2g of dimethyl imidazole into a flask in sequence, and carrying out reflux stirring reaction at 55 ℃ for 10 hours until the mixed solution is clear and transparent to obtain a first single acid monoester mixed solution; Step 02, sequentially adding 310.2g of 3,3', 4' -tetracarboxylic diphenyl ether dianhydride, 46.0g of ethanol, 1240.8g of tetrahydrofuran, 310.2g of N, N-dimethylformamide and 3.2g of dimethyl imidazole into a flask, and carrying out reflux stirring reaction at 55 ℃ for 10 hours until the mixed solution is clear and transparent to obtain a second single acid monoester mixed solution; Step 03, mixing a first single-acid single-fat mixed solution and a second single-acid single-fat mixed solution, adding 554.4g of polyphenyl polymethylene polyisocyanate, continuously stirring until the gas is completely volatilized, adding 6.3g of AK-8805 and 63g of deionized water, continuously stirring for 2 hours at 1000r/min by using mechanical stirring, and then stirring for 2 hours at 20kHz by using microwaves; and 04, injecting air into the mixed solution at a speed of 0.8NL/min, transferring the mixed solution to a mould, and performing free foaming molding under the conditions of 60 ℃ multiplied by 4h, 150 ℃ multiplied by 4h and 220 ℃ multiplied by 4h in sequence to obtain the hyperbranched polyimide flexible foam.

Description

Hyperbranched polyimide flexible foam and preparation method thereof Technical Field The invention relates to the technical field of high polymer materials, in particular to hyperbranched polyimide flexible foam and a preparation method thereof. Background Polyimide foam (PI) is a foam material obtained by a polymerization foaming reaction of a polyimide resin raw material and an auxiliary agent such as a foaming agent and a filler. The polyimide foam molecular chain contains imide ring, the imide ring structure contains heterocycle of nitrogen and oxygen atoms, and the unique rigid imide ring molecular structure endows good heat and oxidation resistance, insulativity, irradiation resistance, low temperature resistance and other performances; the high-performance polyimide foam can resist even extremely low temperature, has the advantage of not breaking at 267 ℃ below zero, is widely applied to the fields of aerospace, aviation, engineering materials and the like, and simultaneously promotes the rapid development of the polyimide foam industry. Chinese patent CN118005987a discloses a method for preparing polymethacrylimide foam (PMI). The copolymer plate is prepared by mixing methacrylic acid, 1-amino octadecane, allyl methacrylate, tridecyl methacrylate, an initiator, a foaming agent and a solvent, stirring, reacting and polymerizing, and then heating and drying stepwise to obtain the polymethacrylimide foam (PMI). In addition, CN in a MAN chain segment can be rearranged to form a trapezoid structure, so that the foam has high strength and high temperature resistance, can be used as a substitute of steel materials in various industries, has high rigidity and high foam density, and is extremely limited in application in the fields of ships, aviation, aerospace and the like. W02004072032A2, U.S. Pat. No. 6956066B2, U.S. Pat. No. 7541388,US 2006063848 and Chinese patent CN114854009A disclose a method for preparing a diacid diester precursor solution by reacting dianhydride, alcohol, catalyst, cross-linking agent, auxiliary material and solvent, and then adding isocyanate into the precursor solution to foam and prepare polyimide foam. The polyimide foam prepared by the method has good comprehensive performance, but the foam has serious slag falling and low tensile strength, and gas can be generated spontaneously and rapidly after isocyanate is added in the processing process, so that the polyimide foam is difficult to stir uniformly, the foaming process is difficult to control, and the yield of foam products is low. U.S. Pat. No. 3, 4804504, 4814357, U.S. Pat. No. 5, 4855332, U.S. Pat. No. 5, 4952611, U.S. Pat. No. 3, 5064867 and Chinese patent CN114044903A disclose a process for preparing a rigid polyimide foam. The polyimide foam is prepared by taking anhydride, norbornyl alcohol, polar solvent, catalyst, aromatic diamine and the like as raw materials to react to generate polyester ammonium salt (PEAS), and heating and foaming the raw materials. The polyimide foam has the advantages of high temperature resistance, good toughness, small compression deformation at high temperature and recycling, but complex flow, and the polyimide chain segment in the foam is of a one-dimensional linear structure and does not generate three-dimensional reticular crosslinking, so that the product has low strength and high temperature resistance deviation, and is difficult to use for a long time in a high-temperature and high-strength complex environment. At present, the polyimide foam is prepared by adopting a self-foaming mode, and the problems of excessively severe foaming process, serious foam collapse and low yield still exist. Therefore, a polyimide flexible foam which has low density, uniform foam cells, qualified strength and low slag drop rate and can be used as a weight-reducing heat-insulating flame-retardant material in the fields of aviation, aerospace, ships and the like is needed to be prepared. Disclosure of Invention The invention provides hyperbranched polyimide flexible foam and a preparation method thereof, which are used for solving the defects of the prior art, and the polyimide foam intermediate prepared by the invention is of a mono-acid mono-lipid structure instead of a diacid di-lipid structure, so that the quality problems of high slag dropping rate and low strength of foam products can be improved. In order to achieve the object of the present invention, the following techniques are proposed: A hyperbranched polyimide flexible foam has a chemical structural formula: ; Wherein, the R1 is selected from: 。 A preparation method of hyperbranched polyimide flexible foam comprises the following steps: step 01, sequentially mixing a first difunctional aromatic dianhydride, an alcohol solvent, an ether solvent and a polar organic solvent, and carrying out reflux stirring reaction to obtain a first single-acid single-fat mixed solution, wherein the reaction temperature is about 55 ℃ and the reaction time is 10-