Foaming type polyurethane wave-absorbing material and preparation method thereof

Abstract

The invention discloses a foaming type polyurethane wave-absorbing material and a preparation method thereof. The foaming type polyurethane wave-absorbing material is prepared in the way that a wave-absorbing material, a fire retardant and an additive are directly added to semi-rigid foam and rigid foam polyurethane which serve as carriers. The preparation method comprises the steps of: firstly, dividing the polyurethane raw material into a component A and a component B, wherein the component A is diisocyanate or a derivative of diisocyanate, the component B is polyether glycol or polyester polyol; adding the additive into the component B, mixing and stirring uniformly for later use, adding the fire retardant and the wave absorbing material in the component A or B in any proportion, respectively pouring the prepared components A and B which are uniformly mixed into two material tanks of a low-pressure polyurethane pouring machine, then pouring the prepared material into a mould by using the pouring machine, foaming for 6-8min and then opening the mould, taking a product out, curing the product for 0.5-2 days, and finishing to obtain the foaming type polyurethane wave-absorbing material. The foaming type polyurethane wave-absorbing material has the advantages of strong wave absorbing property and stable reflectivity, and is suitable for mass production.

Description

technical field [0001] The invention relates to an electromagnetic wave-absorbing material, in particular to a foamed polyurethane wave-absorbing material and a preparation method thereof. Background technique [0002] It is known that absorbing materials are required in the anechoic chamber. The existing absorbing materials use soft polyurethane open-cell foam as the matrix, and then cut into pyramid shapes. The flame-retardant coating that absorbs electromagnetic waves is impregnated in polyurethane It is made by foaming, drying and other processes, and then pasted and installed in the dark room by adhesive. The specific implementation method is to dip and extrude the prepared wave-absorbing and flame-retardant coating into the soft polyurethane foam, and then dry it. Such substances are glued between the pores of polyurethane foam. Because of this processing technology, it is easy to cause uneven distribution of absorbent and flame retardant in the absorbing material, an...

AI Technical Summary

Problems solved by technology

The specific implementation method is to dip and extrude the prepared wave-absorbing and flame-retardant coating into the soft polyurethane foam, and then dry it. Such substances are glued between the pores of polyurethane foam. Because of this processing technology, it is easy to cause uneven distribution of absorbent and flame retardant in the absorbing material, and the consistency of mass production is poor. At the same time, due to the impregnation and drying process , the size of the material expands and shrinks differently, resulting in a large dimensional tolerance of the final wave-absorbing material, and as the wave-absorbing material increases in service life, the adhesive gradually ages, which causes the attached absorbent, flame retardant, etc. to fall off easily. The use environment is seriously polluted, and it is impossible to guarantee a clean test environment. At the same time, due to its own weight, the microwave-absorbing material with a high height (above 700 mm) is prone to bend after 2 years of use. The aesthetics deteriorate and the overall performance is affected; at the same time, the traditional carbon-impregnated polyurethane wave-absorbing materials also have the following technical problems: it is easy to cause uneven distribution of wave-absorbing agents and flame retardants in the matrix material, and poor consistency in mass production. In the impregnation and drying process, due to the inconsistent material size expansion and shrinkage rate, the final size tolerance of the finished microwave absorbing material will be large. Among them, the adhesion of electromagnetic wave absorbing agent and flame retardant in the base material is small, and the finished polyurethane absorbing material During the transportation and handling of microwave materials, wave absorbing agents and flame retardants are easy to lose powder and fall off, and with the increase of service life, aging sinks or elbows are prone to occur, resulting in the deterioration of the product's wave absorbing performance and flame retardant performance. Once it catches fire and burns, it will release a large amount of toxic and harmful gases, which will affect the rescue. The traditional foamed polyurethane absorbing materials basically use a single electromagnetic wave loss material, such as conductive carbon powder and conductive carbon fiber. The mechanism is a single type of electrical loss, which is very unfavorable for widening the frequency band and improving the absorbing performance

This structure is mainly used in occasions that require high flammability, the material is easy to get wet, the paint surface is easy to fall off, the strength is low and there is no elasticity, and the sharp cone is easy to deform when touched, etc. Therefore, in order to solve the problems of traditional absorbing materials Inventing a new type of environmentally friendly absorbing material has become a long-term technical demand for those skilled in the art

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