PURPOSE: To use unvulcanized rubber for all of rubber sheets so as to completely integrate the joined sections thereby making the airtightness of a rubber bag favorable, by positioning unvulcanized rubber sheets containing reinforcing cloth or made up only of rubber to oppose to each other with a rubber member placed between their peripheries, and vulcanizing them.
CONSTITUTION: The joining surfaces of the rubber sheets 1, 2 having the same configuration and the joining rubber member 3 are applied thinly with an adhesive and they are pressed to be bonded tentatively. In this case, a releaser is applied on the opposed intermediate sections of the rubber sheets 1, 2. Then a venting sheet 7 in the form of a fabric or knitted cloth is placed on a lower press hot plate 5, the rubber sheets 1, 2 and the joining rubber member 3 are placed thereon within the periphery thereof, and then a sheet 6 similar to the sheet 7 is placed thereon. The lower press hot plate 5 is elevated, and the rubber bag materials 1, 2, 3 are vulcanized between the press hot plates 4, 5 via the venting sheets 6, 7.
HIROOKA KATSUMI
UEHA KATSUKUNI
NISHINO TOSHIO
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