Patent ID: 8507791

Claim:
A sheet for sealing a rear surface of a solar cell comprising: a laminate in which at least two substrates are attached by an polyurethane-based adhesive, the polyurethane-based adhesive comprising an adhesive having hydrolysis resistance which satisfies the following conditions: condition 1: the lamination strength of the adhesive is 1 N/15 mm or more after keeping the laminate in a chamber which acts as a highly accelerated stress test system under pressurized steam conditions of 105° C. and 1.05 atm for 168 hours; and condition 2: the adhesive does not bring on a delamination and a blister between the substrates after keeping the laminate in a chamber which acts as a highly accelerated stress test system under pressurized steam conditions of 105° C. and 1.05 atm for 168 hours, the polyurethane-based adhesive being an adhesive composition comprising 1 to 50 parts by weight of at least one compound selected from the group consisting of a carbodiimide compound, an oxazoline compound, and an epoxy compound, relative to 100 parts by weight of a composition comprising polyol A and a crosslinking agent, and the polyol A being at least one of polyester polyol and polyester urethane polyol of which a chain is elongated by an isocyanate compound having two or greater functional groups.