Method of making a foamed plastic
AssigneeKabel-und Metallwerke Gutehoffnungshutte Aktiengesellschaft
InventorHans-Martin Schmidtchen
Life of this patent
Estimating the term…
Abstract
An elastomeric or thermoplastic polymer, such as polyethylene, is mixed with silane for grafting onto the polyethylene; after grafting the material is extruded around a cable, a conductor, tubing or the like, but just prior to extrusion moist nitrogen is forced into the extruder so that the material will expand to foam, the cells being filled with moist gas so that the cell walls crosslink to stabilize the resulting foam sheath.
Claims9
In a method of making a cellular, polymeric product, wherein a silane compound is grafted upon a thermoplastic or elastomeric material to permit crosslinking in the presence of moisture, after the grafting-on of the silane, the grafted material being in a fluid state, the improvement of introducing into the grafted material from the outside pressurized, moist gas as a foaming agent, subsequent to grafting, while the grafted material is still in the fluid state, for obtaining and producing cells in the material, the cell walls being exposed to the moisture in the gas and begin crosslinking, and immediately thereafter shaping the material into the desired product.
In a method of coating elongated stock, by means of a cross-linked foam of thermoplastic or elastomeric material, wherein a silane compound has been grafted upon the material, and wherein subsequently the material is extruded onto and around the stock, the improvement of introducing a pressurized, moist gas into the material just prior to extrusion for expanding the material in order to obtain cells and for beginning cross-linking of the cell walls by exposure to the moisture of the blowing gas.
Dependencies are inferred from the claim text.