| 摘要 |
PROBLEM TO BE SOLVED: To provide a panel excellent in sound-insulating properties by polarizing a molding made from a polyamide nm(in which n and m are each an odd number) in an electric field of a specified intensity to cause the molding to have a specified residual polarization. SOLUTION: A dicarboylic acid component (e.g. 1,7-heptanedicarboxylic acid) and a diamine component (e.g. an aq. 1,9-nonamethylenediammoniuym soln.) are copolymerized in the presence of a polymn. modifier (e.g. acetic acid) at a predetermined temp. under pressure and then the pressure is removed. The resultant polyamide nm (in which n and m are each an odd number) is taken out, dried, and extruded through an extruder to give a sheet, which is cooled and solidified on a metal roll and stretched oat room temp. to give a stretched film. The film is polarized in an electric field of 100V/μm or higher to give a polyamide molding having a residual polarization of 45mC/m<2> or higher. The molding 1 is laminated on a porous substrate 2 made from thermoplastic resin fibers, then laminated rock wool 4, and inserted into between plastic boards 3, thus giving a sound-insulating panel.
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