| 摘要 |
A procedure is disclosed for continuous extrusion coating by the use of a coating die of a hollow core material with a highly expanded polyolefin composition containing a volatile organic liquid blowing agent, the improvement comprising externally, cooling the outer surface of the extruded molten mass of expandable polyolefin resin, at the point at which the molten mass begins to foam, by by contacting the surface with a cooling gas or water to allow the pressure of foaming to be exerted inwardly and also to cause the growth of foam to proceed in the direction of the internal core for thereby enabling the polyolefin foam to adhere fast to the hollow core and giving rise to a coating having a smooth surface condition, wherein the expanded polyolefin foam has an expansion ratio of not less than 3. This thereby enhances the fastness of adhesion of the highly expanded polyolefin foam with the hollow core material and at the same time facilitates the release of the two materials thus joined. |
