Preparation method for polymethacrylimide composite foam conductive wave-absorbing material

Abstract

The invention specifically relates to a preparation method for a polymethacrylimide composite foam conductive wave-absorbing material, belonging to the field of preparation of novel materials. The preparation method comprises the following steps: weighing (meth)acrylic acid, (meth)acrylonitrile, a third monomer, a functionalized wave-absorbing agent, a dispersing agent, an anti-settling agent, aninitiator, a nucleating agent, a polymerization inhibitor, a cerium-containing foaming material and a cross-linking agent, adding the weighed substances into a reaction vessel, and performing a polymerization reaction to prepare an expandable polymethacrylimide resin particle; and then mixing the expandable polymethacrylimide resin particle with a binder, an auxiliary agent, the functionalized wave-absorbing agent and a fibrous substance, and carrying out preheating and foaming to obtain the polymethacrylimide composite foam conductive wave-absorbing material. The material of the invention hasgood wave-absorbing properties, heat resistance and mechanical properties, can be used for preparing special-shaped parts, and can avoid defects such as complicated process and wasting of materials during mechanical processing of materials for acquisition of complicated shapes.

Description

technical field [0001] The invention relates to the field of material preparation, in particular to a preparation method of a polymethacrylimide composite foam conductive wave-absorbing material. Background technique [0002] Polymethacrylimide foam (PMI) is a cross-linked, uniform pore size distribution foam with excellent structural stability and high mechanical strength. Polymethacrylimide foam has higher specific strength, specific modulus, heat resistance and heat and humidity resistance than other polymer foam materials, as well as better high temperature creep resistance and dimensional stability. Its outstanding heat resistance and excellent creep resistance at high temperatures enable it to withstand the high temperature curing process conditions of thermosetting resin composite materials such as epoxy and Shuangma, and can realize one-time co-curing molding of foam sandwich and prepreg, It can be widely used in the manufacture of composite material foam sandwich s...

AI Technical Summary

Problems solved by technology

[0005] Chinese patent No. 200710117643.4 discloses a preparation method of polyacrylimide foam material and its products. The material produced by this method basically does not have wave-absorbing properties

[0006] Chinese patent application No. 200710159605.5 discloses a kind of expandable particles used to produce polymethacrylimide foam materials. Due to the polymerization characteristics of this type of polymer, it is easy to precipitate during the process of adding high-density wave absorbing agent , and it is not possible to add dense absorbers such as some magnetic absorbers, which cannot achieve low-frequency absorbing performance

[0008] The Chinese patent application with the application number 200810031468.1 uses the method of using functional powder additives in the polymerization raw material mixture. Due to the chemical characteristics, viscosity characteristics, density characteristics of the raw materials, and the characteristics of free radical polymerization, the types of additives, The amount used is limited, resulting in limited absorption of functional foams obtained in this way

Similarly, it does not carry out surface treatment on this type of absorbing material, and it cannot make the absorbing material evenly dispersed in the PMI system, so that the absorbing performance of each part of the PMI foam material is greatly different, which limits the use of this type of absorbing material. Practical Applications of Wave Materials

[0009] Chinese patent application CN200910102124.X discloses a method for preparing a wave-absorbing PMI foam sandwich structure composite material. This preparation method has the following defects in the actual use process: first, the added wave-absorbing agent has not been functionalized, and the absorbing When the wave agent is added in a small amount, the wave-absorbing performance is poor; when it is added in a large amount, it often has a great influence on the polymerization reaction, which makes the foamable foam material not evenly foamed or even normally foamed.

In actual use, the foam materials synthesized by this method often have defects such as insufficient foaming, easy settlement, poor mechanical properties, poor wave-absorbing performance, and low wave-absorbing strength.

Moreover, there are fewer types of absorbing agents added, which only have absorbing properties in certain frequency ranges, and do not have wider frequency absorbing properties.

The wave-absorbing performance of the foam sandwich structure is not uniform, and most of the wave-absorbing agent is concentrated on a certain interface, and the test results in different directions are quite different. If the structure is cut and tested, it will be found that the The absorbing performance is also very different

[0010] It can be seen from the above that polymethacrylimide foam materials with good mechanical properties and good wave-absorbing properties are relatively scarce at present.

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