| 摘要 |
<p>PURPOSE: To obtain a crosslinked polyethylene pipe, prominent in resistances to chemicals, high-temperature creap, shock as well as flexibility and improved in productivity, by a method wherein an inner layer is made of Engel crosslinked high-density polyethylene while an outer layer is made of silane crosslinked low-density polyethylene. CONSTITUTION: An inner layer is made of Engel crosslinked high-density polyethylene while an outer layer is made of silane crosslinked low-density polyethylene. The inner layer is made by mixing organic peroxide into high-density polyethylene or a base resin while the outer layer is made by mixing silane compound, organic peroxide and silane contracted catalyst into a base resin or the low-density polyethylene. The outer layer is formed on the inner layer through extrusion molding and, thereafter, is heated at a temperature lower than the decomposing temperature of the organic peroxide, then, is heated to a temperature higher than the decomposing temperature of the organic peroxide. Thereafter, crosslinking treatment is applied under the existence of moisture. The pipe, made by such a manner, is provided with the inner layer of Engel, crosslinking and only the outer layer is made through silane crosslinking whereby the pipe is prominent in flexibility and a silane crosslinking treatment time can be shortened.</p> |
