Solventless laminating adhesive with barrier properties

A method of laminating a first film of polymeric material to a second film of polymeric material comprising

• providing, in molten form, a solventless, hydroxyl-terminated polyester A) formed from a single species of a linear aliphatic diol having from 2 to 10 carbons and a single species of a linear dicarboxylic acid, said polyester having a number average molecular weight from about 300 to about 5000 and a melting point of 80° C. or below,
• providing, in liquid form, a single species of diisocyanate B),
• either
• mixing said diisocyanate B) and said polyester A) at an NCO/OH ratio of between about 1 and about 1.1 to form an adhesive mixture (I),
• or
• reacting all of or a portion B′) of said diisocyanate B) with a portion A′) of said polyester A) at an NCO/OH ratio of between about 2 and about 8 to form a urethane prepolymer C) and mixing the remaining portion A″) of said polyester A) and any remaining portion B″) of said diisocyanate B) with said urethane prepolymer C) to form an adhesive mixture (II), the NCO/OH ratio of A) to B) being between about 1 and about 1.1,
• adhering said first and said second film with either of said adhesive mixtures (I) or (II),
• and
• allowing said diisocyanate B) and sad polyester A) to fully react.