Low density oriented polymer composition with inert inorganic filler

Abstract

An oriented polymer composition containing thirty to 95 weight-percent inert inorganic filler and a continuous phase of at least one orientable polymer contains void spaces due to cavitation and has a density of less than 0.8 grams per cubic centimeter, a flexural modulus of 1.4 gigapascals or more, cross section dimensions all greater than 1.5 millimeters, a delamination force value of 44.5 Newtons (ten pounds force) or more and little or no blowing agent.

1 . An oriented polymer composition comprising thirty weight-percent or more and 95 weight-percent or less inert inorganic filler based on oriented polymer composition weight and a continuous phase of at least one orientable polymer, wherein the oriented polymer composition has: (a) a density of less than 0.8 grams per cubic centimeter according to ASTM method 792-00; (b) a flexural modulus of 1.4 gigapascals (200,000 pounds per square inch) or more according to ASTM method D-790-03; (c) cross section dimensions all greater than 1.5 millimeters; (d) a delamination force value greater than 44.5 Newtons (ten pounds force); and wherein the oriented polymer composition contains less than three weight-percent blowing agent based on oriented polymer composition weight. 
     
     
         2 . The oriented polymer composition of  claim 1 , wherein the filler is selected from a group consisting of talc, calcium carbonate, clay and fly ash. 
     
     
         3 . The oriented polymer composition of  claim 1 , wherein the orientable polymer is one or more than one semi-crystalline polymer. 
     
     
         4 . The oriented polymer composition of  claim 1 , wherein the orientable polymer is selected from polypropylene-based polymers, polyethylene-based polymers, polyvinyl chloride, polyesters and polyester-based polymers. 
     
     
         5 . The oriented polymer composition of  claim 1 , wherein the oriented polymer composition is free of blowing agent. 
     
     
         6 . A process for solid state drawing a polymer composition comprising the steps: (a) providing a polymer composition comprising thirty weight-percent or more and 95 weight-percent or less of an inert inorganic filler based on polymer composition weight and a continuous phase of at least one orientable polymer, the polymer composition having a melt temperature; (b) conditioning the temperature of the polymer composition to a drawing temperature that is ten degrees Celsius or more below the polymer composition's softening temperature; (c) drawing the polymer composition though a drawing die at a drawing rate of at least 0.25 meters per minute; and (d) optionally, cooling the polymer composition after it exits the drawing die; wherein the polymer composition comprises less than three weight-percent blowing agent based on polymer composition weight. 
     
     
         7 . The process of  claim 6 , wherein drawing in step (c) achieves a linear draw ratio of 10 or less. 
     
     
         8 . The process of  claim 6 , wherein the orientable polymer is one or more than one semi-crystalline polymer. 
     
     
         9 . The process of  claim 6 , wherein the orientable polymer is selected from polypropylene-based polymers, polyethylene-based polymers, polyvinyl chloride and polyester-based polymers. 
     
     
         10 . The process of  claim 6 , wherein the draw rate is 0.5 meters per minute or faster. 
     
     
         11 . The process of  claim 6 , wherein the draw rate is one meter per minute or faster. 
     
     
         12 . The process of  claim 6 , wherein the drawing temperature is at least fifteen degrees Celsius below the polymer composition's softening temperature. 
     
     
         13 . The process of  claim 6 , wherein the drawing temperature is at least twenty degrees Celsius below the polymer composition's softening temperature. 
     
     
         14 . The process of  claim 6 , wherein the draw temperature is forty degrees Celsius or less below the polymer composition's softening temperature. 
     
     
         15 . The process of  claim 6 , wherein the filler is selected from talc, clay, calcium carbonate and fly ash. 
     
     
         16 . The process of  claim 6 , wherein the filler is present at a concentration of 40 percent by weight or more relative to polymer composition weight before drawing. 
     
     
         17 . The process of  claim 6 , wherein the polymer composition experiences a nominal draw ratio of 1.25 or more and less than five. 
     
     
         18 . The process of  claim 6 , wherein drawing is done through a drawing die that induces proportional drawing of the polymer composition. 
     
     
         19 . The process of  claim 6 , wherein the polymer composition is free of blowing agent.