Balloon having a self sealing valve and method of making same

A method of making a balloon comprising the steps of:

• bonding first and second flexible valve sheets together in face-to-face relation to form a self-sealing valve having a valve inlet and a valve outlet, said first and second flexible valve sheets each having an inlet end, an outlet end, and an intermediate region between the inlet end and the outlet end, a bond resistant agent being within the valve sheets for selectively preventing bonding of the intermediate regions of the valve sheets, the inlet end of said second valve sheet extending beyond the inlet end of said first valve sheet to define an extended portion of said second valve sheet;
• bonding the valve to one of first and second balloon sheets, each balloon sheet having a body portion and a stem portion extending outwardly from the body portion and terminating at a stem end, the stem portion of said first balloon sheet being shorter than the stem portion of said second balloon sheet, the stem portions of said balloon sheets having edge margins extending from adjacent the body portions to their stem ends;
• positioning said first balloon sheet generally face to face with said second balloon sheet, and with at least a portion of said valve being disposed between the stem portions of said first and second balloon sheets;
• bonding said valve to said balloon sheets along the edge margins of the stems of said balloon sheets to form first and second edge seals extending from adjacent the body portions of said balloon sheets to adjacent the stem ends of said balloon sheets;
• and
• bonding said first and second balloon sheets together generally around the periphery of said balloon sheets with the stem end of said second balloon sheet extending beyond the stem end of said first balloon sheet to define an extended portion of said second balloon sheet, and with the inlet end of said second valve sheet overlying the extended portion of said second balloon sheet and being coterminous with the stem end of the second balloon sheet, the extended portion of said second balloon sheet and the extended portion of said second valve sheet combining to form a guide tongue for facilitating insertion of a gas supply nozzle into the valve inlet during inflation of the balloon.