| 摘要 |
PURPOSE:To obtain a pressure diaphragm useful for industrial pressure sensor, having excellent pressure resistance, dimensional stability and heat resistance by adding a specific amount of a swelling agent to a para-based aramid polymer, setting a film in a given retaining frame and removing the swelling agent. CONSTITUTION:A para-based aramid polymer (e.g. poly p-phenylene terephthalamide) having 5.5 logarithmic viscosity is dissolved in 99.5% conc. sulfuric acid to give 12wt.% dope, the dope is cast into a tantalum endless belt, air having 40% relative humidity and room temperature is heated to 90 deg.C and blown on the film, and the film is coagulated in 40% aqueous solution of sulfuric acid at 0 deg.C, then the acid is neutralized with a aqueous solution of sodium hydroxide and the film is washed with water to give a gelationus film having >=7% based on the polymer of water of a swelling agent. The gelatinous film 1 is extended and stuck to a protecting film 2 so as not to produce wrinkles, fixed by a pressing metal 3, dried in a hot-air oven at 150 deg.C and the swelling agent in the film is removed to give the objective pressure diaphragm. |
