| 摘要 |
PROBLEM TO BE SOLVED: To obtain an electromagnetic wave-shielding material comprising a metal salt crosslinked product of an expanded (co)polymer having excellent lightweight properties and electromagnetic wave-shielding properties, high compressive strength and heat insulation properties, by using anα,β-unsaturated carboxylic acid and optionally other vinyl monomers as the constituent monomers and simultaneously performing the expansion and polymerization in the presence of a (heavy) metal salt. SOLUTION: From the viewpoint of cost, theα,β-unsaturated carboxylic acid is desirably acrylic acid or methacrylic acid. The vinyl monomer is exemplified by (meth)acrylamide, (meth)acrylic acid/alkylene oxide adduct, acrylonitrile or vinyl acetate. It is desirable that theα,β-unsaturated carboxylic acid constitutes at least 30 wt.% of the (co)polymer. The (heavy) metal carbonate used is desirably a salt of a polyvalent metal such as Ca, Mg, Ba, Zn, Al, iron or copper, and the metal salt crosslinked product of the (co)polymer constitutes at least 30 wt.% of the total weight of the shielding material.
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