グラファイトとポリ塩化ビニルを複合化したスピーカの振動板用材料

概要

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Graphite/Polymer composite named PG is studied for loudspeaker diaphragm material. Polyvinyl chloride(PVC)and graphite powder with flake shape(the mean grain size5μm)are mainly used as raw materials for PG. Increment of the graphite contents results in a high Young's modulus and a high breaking strength provided with an almost equal internal loss. However, the maximum graphite content is found to be 65wt%. In this case following physical properties are obtained:the sound velocity of about6×10^3m/sec, which is20% faster than that of aluminum or titanium, and tanδ of about 0. 02. This latter value can be further increased up to 0. 045by adding 30wt% polyvinylidene chloride into the PVC. The temperature and frequency dependences of Young's modulus and tanδ of the PG are small up to40℃. The heat deformation temperature(HDT)of the PG cone-type diaphragm with 45mm diameter and 0. 07mm thickness is about 70℃. By replacing usaual PVC with post chlorinated PVC, the HDT can be raised about 100℃. Examining the orientation of the graphite flakes with an X-ray diffractometer, it is proved that the high Young's modulus in the PG sheet is attributed by highly oriented graphite flakes. A 12cm shallow type cone loudspeaker using the PG diaphragm(88mm diameter, 8mm depth)has a smooth frequency response up to 20kHz and has very low harmonic distortion cahracteristics.
社団法人日本音響学会の論文
1982-10-01