Insulating Urethane-forming curable compositions and insulated electric or electronic part or device

Abstract

A urethane-forming curable composition which has a low viscosity and therefore can sufficiently flow around to details or minute cavities 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. 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.

Dependencies are inferred from the claim text.