Method for preparing foaming materials by nitrogen foaming

Abstract

The invention relates to the field of physical foaming. The method includes the following steps: crosslink the foaming matrix to obtain a plurality of crosslinked prefabricated products, add the crosslinked prefabricated products into a reaction reactor filled with polar liquid, add nitrogen for foaming, relieve pressure, and heat for foaming to obtain the foaming materials. In the polar liquid system, the inventor finds that the ratio of the distance between the adjacent crosslinked prefabricated products to the thickness of the prefabricated products as well as the difference between the melting temperature of the polymer and the temperature of the polar liquid need to be controlled to promote the adjacent prefabricated products in full contact with the polar liquid, and prefoaming can be carried out under the condition of low temperature difference, namely, at the low temperature of the polar liquid.