| 摘要 |
A metallized film capacitor is provided with a polyurethane oil insulating fluid. The insulating fluid has a viscosity in the range of about 500 to 3000 poise at 25 DEG C. The polyurethane oil insulating fluid is produced by reacting an organic polyisocyanate with a primary polyol selected from the group consisting of castor oil, ricinoleic acid derivatives of castor oil and mixtures thereof. The reaction may be carried out in the presence of a secondary polyol chain extender such as a hydroxy-terminated polybutadiene diol. The reaction to produce the insulating fluid is carried out under conditions wherein the ratio of NCO groups of the organic polyisocyanate to OH groups of the primary and secondary polyols, if present, is in the range of about 0.1 to 1 to about 0.6 to 1. The ratio ensures that there is no excess of unreacted NCO groups in the insulating fluid and that the reaction produces a viscous fluid, not a substantially solid elastomer.
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