PURPOSE: To stabilize heat-shrinkable properties and to enhance production efficiency, by fusion bonding a heat shrinkable layer constituting material and a fusion bonded layer constituting material while sending a high temp. heating medium into a pipe in such a state that a pair of ribs are pressed to the surface of the pipe.
CONSTITUTION: After a fusion bonding layer constituting material 13 is wound around a pipe 10 in a necessary thickness, the circumferences of ribs 6 are pressed to mutually closely adhere a plate like protruded part 11, the fusion bonded layer constituting material 13 and a heat shrinkable layer constituting material 14. Subsequently, a high temp. heating medium is sent into the fluid passage 12 of the pipe to fusion bond the fusion bonded layer constituting material 13 while heating the same to a fusion bonding temp. In the next step, a low temp. heating medium is passed through the fluid passage 12 of the pipe 10 to cool both constituting materials 13, 14 through the pipe 10 to solidify the fusion bonded part and, upon the detachement from the pipe 10, a heat shrinkable sheet 3 having a fusion bonded layer 3a and a heat shrinkable layer 3b and having a specific configuration in the vicinity of a pair of the ribs 6 is obtained.
SUZUKI HIDEO
NAKANO KOUSAKU
ISHIZAKA YOSHIYUKI
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