2018 Volume 54 Issue 10 Pages 367-373
Water vapor transmission rates of nine kinds of adhesives were measured under conditions of temperature25 to 85 ℃ and 90 ％ relative humidity by the improved cup method we developed. A laminated film obtainedby coating an adhesive on a cellulose triacetate film was used as a test specimen and the water vaportransmission rate of the adhesive alone was estimated from the measured value of the laminated specimenmeasured by the cup method. For the high-temperature measurement conditions of 60 ℃ and 85 ℃, theimproved cup incorporating a pressure adjustment mechanism was used to avoid damage to the test specimendue to the variation of pressure in cup occurring during the measurement. The water vapor transmissionrate of the adhesive measured at 85 ℃ was quite different from that in the normal temperature range, whichwas 10 to 85 times as compared with 25 ℃ and 5 to 20 times as compared with 40 ℃. The silicone typeand polyurethane type adhesives had a water vapor transmission rate per unit thickness of 9 to 80 times ascompared with epoxy type adhesives in the entire measuring temperature range.
