| 摘要 |
PROBLEM TO BE SOLVED: To omit a crosslinking process by leaving crosslinker-containing polyethylene tubes formed by extrusion stand in the atmosphere, in lots, to be crosslinked, sampling it periodically to determine the degree of crosslinking, and shipping the tubes having reached a target degree of crosslinking. SOLUTION: Polyethylene to which a silane crosslinker is added is extruded from an extruding machine, so that a crosslinker-containing polyethylene tube be formed. This tube is cut at each prescribed length and the crosslinker- containing polyethylene tubes prepared in this way and bundled are left, as it is, on a floor surface in a building. They are sampled respectively just after the forming, on the 10th day, on the 17th day and after one month, for instance, and a gel molar fraction of the sampled polyethylene tube is measured. Herein the gel molar fraction is made an index of the degree of crosslinking. Shipping is made for the tubes having reached a target gel molar fraction, e.g. for those having been left for 10 days or longer. According to this constitution, a crosslinking process can be omitted and thereby the cost can be reduced. |
