PURPOSE: To easily bond sheets within a relatively short time by a method wherein the joint parts of the sheets are superposed one upon another to bond or weld the sheets along the joint parts thereof in an almost strip-like state and a swellable substance layer is provided to the non-bonded or non-welded parts of the sheets.
CONSTITUTION: When the terminal part of a sheet 1a is welded to a sheet 1b, a swellable substance layer 2 may be formed to the entire surface of the sheet 1a or said layer 2 may be formed to the sheet 1b in the vicinity of the terminal part thereof but not formed to the other part thereof. A protective tape may be provided to the bonded end part of the sheet 1a. When the terminal part of the sheet 1a is bonded to the sheet 1b by an adhesive 4, the protective tape may be provided to the bonded end part of the sheet 1a. By this constitution, the sheets can be laid within a relatively short time and the leakage of water, an org. solvent, chemicals or oil can be prevented without lowering the strength of the sheets.
NAKAMURA GENZO
MURAKAMI HIROSHI
