Electrically insulating, curable polyurethane compositions and electric or electronic device made therewith

摘要

The present invention has for its object to provide a urethane-forming curable composition which has a low viscosity and therefore can sufficiently go round to details or minute cavities or the like of electric or electronic parts or devices to seal the same and which can give flexible curing products excellent in heat resistance, hydrolysis resistance (wet heat resistance) and moistureproofness and capable of preventing hardness changes as well as reductions in insulating performance over a long period of time even under severe conditions and therefore can reliably protect the electric or electronic parts or devices, and to provide insulated electric or electronic parts or devices treated for moistureproofness with the curing product produced from the composition. A hydrogenated OH-containing liquid polyisoprene (X) and a polyester polyol (Y) which is liquid at ordinary temperature and is constituted of fatty acid units (A) and polyhydric alcohol units (B) and which has an iodine value of not more than 50 are combinedly used as the polyol component. The fatty acid units (A) of this polyester polyol (Y) at least partly comprise hydroxy fatty acid oligomer (at least dimer) units (a). Electric or electronic parts or devices are treated for moistureproofness with the curing product of this urethane-forming curable composition.