PURPOSE: To easily prepare a pipe having a uniform wall thickness and a large (inner diameter of about 300mm or more), by adhering the overlapped parts of a longitudinally overlapped water crosslinkable polyolefin long sheet by using a water closslinkable adhesive.
CONSTITUTION: Water crosslinkable polyolefine (e.g., water crosslinkable polyethylene obtained by graft-polymerizing polyethylene by using org. peroxide such as vinyl trimethoxysilane) is subjected to extrusion molding from a T-die to fabricate a sheet with a thickness of about 5W30mm. In the next step, this sheet is attached to a mandrel so as to longitudinally overlap both side edges thereof while hot air is blown to the overlapped part of the sheet to heat the same and melted water crosslinkable polyolefin is applied to the gap of the overlapped part which is, in turn, heated to a temp. about 60W160°C higher than the m.p. of the above mentioned polyolefin to be welded and cooled while pressed under proper pressure to prepare a pipe.
MOMOSE CHIAKI
TERASAKI KAZUNORI
