(57) The invention relates to the field of physical foaming, in particular to C08J9/12.
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, to promote the foaming ratio and the cell uniformity.
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