Method for extruding a cross-linked material

Claim 1

A method for continuously extruding in a closed environment an insulating material cross-linked by the separate addition of a cross-linking agent, which method comprises the following steps: (1) passing a cross-linkable insulating material through an extrusion machine provided adjacent its outlet end with a filtering means and at said outlet end with an extrusion head, said extrusion machine being heated to a temperature between about 200° and 220° C., said temperature being about the maximum temperature admissible for said material, so as to bring said material in a substantially fluid condition; (2) cooling the thus filtered material to a temperature between about 140° and 150° C. which temperature is slightly lower than the reaction temperature of the cross-linking agent; (3) injecting said cross-linking agent into said thus cooled material; and (4) conveniently mixing said cross-linkable material and said cross-linking agent; and thereafter (5)elevating the temperature of the mixture of step (4) to a temperature about the maximum temperature admissible for the extrusion of said extrudate before it leaves said extrusion head.

Claim 2

A method for continuously extruding in a closed environment an insulating material cross-linked by the separate addition of a cross-linking agent, which method comprises the following steps: (1) passing a cross-linkable insulating material through an extrusion machine provided adjacent its outlet end with a filtering means and at said outlet end with an extrusion head, said extrusion machine being heated to a temperature between about 200° and 220° C., said temperature being about the maximum temperature admissible for said material, so as to bring said material in a substantially fluid condition; (2) cooling the thus filtered material to a temperature between about 140° and 150° C. which temperature is slightly lower than the reaction temperature of the cross-linking agent; (3) injecting said cross-linking agent into said thus cooled material; and (4) conveniently mixing said cross-linkable material and said cross-linking agent; and thereafter (5)elevating the temperature of the mixture of step (4) to a temperature about the maximum temperature admissible for the extrusion of said extrudate before it leaves said extrusion head.

Claim 10

A method for continuously extruding a cross-linked insulating material in an extrusion machine comprising a housing and an extrusion head, said method comprising the steps of: introducing a cross-linkable material within said housing, forcing said material towards said extrusion head while heating same at a first elevated temperature, filtering said thus heated material at said first temperature, cooling said thus filtered material at a second temperature lower than said first temperature, injecting into said thus cooled material a cross-linking agent, and heating the thus obtained mixture at a third temperature higher than said second temperature and extruding said mixture.

Claim 11

A method for continuously extruding a cross-linked insulating material in an extrusion machine comprising a housing and an extrusion head, said method comprising the steps of: introducing a cross-linkable material within said housing, forcing said material towards said extrusion head while heating same at a first elevated temperature, filtering said thus heated material at said first temperature, cooling said thus filtered material at a second temperature lower than said first temperature, injecting into said thus cooled material a cross-linking agent, and heating the thus obtained mixture at a third temperature higher than said second temperature and extruding said mixture.