초록 ▼

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 age

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.

대표청구항 ▼

[ What is claimed is:] [1.] A short time frame extrusion foaming process for producing a closed-cell propylene polymer foam, comprising the steps of:(a) feeding a propylene polymer resin into an extruder;(b) adding a nucleating agent to the resin feed;(c) plasticating the mixture in an extruder to f

[ What is claimed is:] [1.] A short time frame extrusion foaming process for producing a closed-cell propylene polymer foam, comprising the steps of:(a) feeding a propylene polymer resin into an extruder;(b) adding a nucleating agent to the resin feed;(c) plasticating the mixture in an extruder to form a polymeric melt;(d) incorporating at least one member selected from the group consisting of at least one organic blowing agent, at least one inorganic blowing agent and blends thereof, into the polymeric melt to form a foamable composition;(e) uniformly mixing and cooling the foamable composition to a temperature effective for the expansion of the low-density propylene polymer foam; and(f) extruding or ejecting the foamable composition mixture through a die at a sufficiently high rate to form a low density closed-cell propylene polymer foam characterized by a Foamability Index greater than 1.9 and an Ebullition Time less than 2.0.times.10.sup.-4 seconds.