| 摘要 |
PURPOSE:To establish the speaker rich in the heat resistance, light and highly efficient, by pressing and heating the polyparabanic acid foaming film of specific density made of the copolymer of methylenediisocyanate and hydrocyanic acid. CONSTITUTION:The polyparabanic acid foaming film 0.4-1.0 in density obtained with the copolymer of methylenediisocyanate and hydrocyanic acid is used to form the dome diaphragm plate by heating and pressing the material. Further, molten film is formed on one side of the foaming layer and porosity of foaming layer is choked with molten film. Thus, the speaker excellent in the heat resistance and light and highly efficient can be obtained. |
