Tenneco Protective Packaging, Inc.

Harris A Dunbar

Gary R Wilkes

Kim A Bly

Eugene R Uhl

Jeffrey J Stimler

James L Zwynenburg

A method of making a polyolefinic foam composition comprising the steps of:

Oxygenated hydrocarbon compatibilizing agent for carbon dioxide-blown

Members either of the polyglycol family of substances, more generally, or of the polyglycol ether subset of polyether compounds, more particularly, both for their gas absorption properties and for their plasticizing effect in a polyethylenic extrudate, are combined with physical atmospheric blowing agents, such as, nitrogen, argon, carbon dioxide, water, and blends thereof, to produce uncrosslinked polyethylenic foams having densities as low as 10 kg/m.sup.3.

Process for producing low density polethylenic foam with atmospheric

Process for producing low density polyethylenic foam with atmospheric

A propylene homopolymer or copolymer, or a blend thereof, possessing both sufficient strain hardening, viscoelastic behavior, and melt ductility is heated, melted, and mixed in an extruder with an organic or inorganic physical blowing agent, or a mixture of organic and inorganic physical blowing agents, and with optional compatibilizing agents, nucleating agents, stabilizers and miscellaneous additives. This mixture is pressurized and, subsequently, is cooled to an appropriate temperature at an elevated pressure, and is extruded through a die at rates in excess of 1000 kg/hr to produce an expanded and dimensionally-stable, predominately closed cell propylene polymer foam with a density of between 10 kg/m.sup.3 and 150 kg/m.sup.3, and with a thickness in excess of 1.3 cm. The resultant foamed structure is characterized by a Foamability Index of greater than 1.9 and an Ebullition Time of less than 2.0.times.10.sup.-4 seconds.

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Corinth, NY, United States of America

Harris A Dunbar