Abstract
A recent development in heat insulating materials offers decreased energy consumption for air-conditioning and an improvement in the thermal performance of the insulating glass in windows and the openings of houses and buildings. In insulating glass, the use of a resin spacer, rather than an aluminum spacer, is useful for improving insulation efficiency, but water vapor is still transmitted into the air space of the insulating glass, leading to dew condensation and decreased transparency. The lifetime of resin spacers is predicted by the diffusion coefficient of water vapor without knowledge of the dew point of the insulating glass. The amount of water adsorbed in various resin spacers of polyisobutylene with zeolite 4A was measured at temperatures of 40–80°C and relative humidities of 15–95% at atmospheric pressure from one hour up to one month. In this study, the relationships between the lifetime of the insulating resin, the adsorbed amount of water, and the optimum resin spacer components for increased lifetime are discussed. In addition, a diffusion model for the transmission of water into the air space is proposed.
