Method and system for manufacturing foamed polyolefin tapes at cost effective line speeds

Abstract

Making foamed polyeolefin tapes include combining a polyolefin resin and a chemical blowing agent to form a mixture. This mixture can then be heated in an extruder to create a supersaturated solution of gas within the polyolefin resin. A cooling device can be positioned adjacent to a die at a set distance for receiving extruded resin and for allowing exposure of the extruded resin to ambient air. This space between the cooling device and die outlet allows bubbles to grow in the extruded resin and to be shaped such that voids or empty spaces can be generated within the extruded polyolefin resin. The voids allow the formation of tapes which use less material but have adequate strength for various applications, such as carpet backings, geotextiles, packaging, housewrap, bags, wire insulation, and reinforcement elements in concrete.

1 - 23 . (canceled) 
     
     
         24 . A tape formed by
 heating and shearing a mixture comprising a polyolefin resin and a blowing agent in an extruder to create a supersaturated solution of gas within the polyolefin resin;   maintaining a pressure within the extruder and a die that keeps gas dissolved within the polyolefin resin;   feeding the polyolefin resin to the die;   positioning a heat removal device at a predetermined distance from an outlet of the die;   extruding the gas-saturated polyolefin resin through the die;   exposing the extruded resin to atmospheric pressure for a predetermined amount of time based on the predetermined distance between the cooling device and the outlet of the die;   removing heat from the foamed polyolefin resin with the heat removal device to form a foamed polyolefin resin sheet;   transferring the foamed polyolefin resin sheet away from the heat removal device;   dividing the drawn foamed polyolefin resin sheet into tapes;   extending the tapes by a predetermined factor above their original length; and   maintaining line speeds for the tapes at or in excess of 850 feet per minute wherein the void content of the tape comprises about 2.0% to about 15.0%.   
     
     
         25 . A system for manufacturing polyolefin tapes comprising:
 an extruder for heating and shearing a mixture comprising a polyolefin resin and a blowing agent to create a supersaturated solution of gas within the polyolefin resin,   a die for receiving and extruding the polyolefin resin;   a heat removal device positioned at a predetermined distance from an outlet of the die for receiving an extruded resin flowing through the outlet;   a heat removal device for removing heat from the resin to form a resin sheet, the heat removal device comprising a liquid quenching bath; and   a vacuum device for removing liquid from the resin sheet, the vacuum device comprising a plate with a plurality of grooves.   
     
     
         26 . The system of  claim 25 , wherein each groove has a varying depth. 
     
     
         27 . The system of  claim 25 , wherein each groove has a varying width. 
     
     
         28 . The system of  claim 25 , wherein the vacuum device comprises a conduit coupled to the plate. 
     
     
         29 . A tape formed by:
 providing a mixture comprising a polyolefin resin and a blowing agent;   heating and shearing the mixture in an extruder to create a supersaturated solution of gas within the polyolefin resin;   maintaining a pressure within the extruder and a die that keeps gas dissolved within the polyolefin resin;   feeding the polyolefin resin to the die;   positioning a heat removal device at a predetermined distance from an outlet of the die;   extruding the gas-saturated polyolefin resin through the die;   exposing the extruded resin to atmospheric pressure for a predetermined amount of time based on the predetermined distance between the cooling device and the outlet of the die;   removing heat from the foamed polyolefin resin with the heat removal device to form a foamed polyolefin sheet;   transferring the foamed polyolefin sheet away from the heat removal device;   dividing the drawn foamed polyolefin sheet into tapes;   extending the tapes by a predetermined factor above their original length; and   maintaining line speeds for the tapes at or in excess of 850 feet per minute wherein the maximum thickness of the foamed oriented polyolefin tape comprises 4 mils.   
     
     
         30 . A tape formed by:
 heating and shearing a mixture comprising a polyolefin resin and a blowing agent in an extruder to create a supersaturated solution of gas within the polyolefin resin;   maintaining a pressure within the extruder and a die that keeps gas dissolved within the polyolefin resin;   feeding the polyolefin resin to the die;   positioning a heat removal device at a predetermined distance from an outlet of the die;   extruding the gas-saturated polyolefin resin through the die;   exposing the extruded resin to atmospheric pressure for a predetermined amount of time based on the predetermined distance between the cooling device and the outlet of the die;   removing heat from the foamed polyolefin resin with the heat removal device to form a foamed polyolefin resin sheet;   transferring the foamed polyolefin resin sheet away from the heat removal device;   dividing the drawn foamed polyolefin resin sheet into tapes;   extending the tapes by a predetermined factor above their original length; and   maintaining line speeds for the tapes at or in excess of 850 feet per minute wherein the maximum thickness of the foamed oriented polyolefin tape comprises 4 mils.