HIGH STRENGTH EXTRUDED THERMOPLASTIC POLYMER FOAM
First Claim
1. An extrusion foam process, the process comprising preparing at a mixing pressure a foamable polymer mixture comprising a thermoplastic polymer and a blowing agent, cooling the foamable polymer mixture and extruding it in an extrusion direction through a foaming die at a die pressure and out of the foaming die through a die opening at a flow rate into an atmosphere of low enough pressure to allow the foamable polymer mixture to expand into a polymer foam while traveling in the extrusion direction at an extrusion rate, the extrusion foam process being further characterized by:
- a. the die pressure being at least 90 bars lower than the mixing pressure;
b. all cross sectional dimensions of the die opening being at least 2.5 millimeters and the cross sectional area of the die opening being at least 700 square millimeters;
c. the flow rate of the foamable polymer mixture through the die opening being greater than 500 kilograms per hour;
d. the foamable polymer mixture expands between restraining elements positioned immediately after the foaming die;
e. a device positioned after the restraining elements that restrains the extrusion rate of the polymer foam relative to its unrestrained extrusion rate;
and wherein the polymer foam characterized by having a continuous thermoplastic polymer matrix defining cells therein, a void volume of 96 volume percent or less based on total polymer foam volume, a cell size dimensional ratio in the polymer foam thickness dimension to its width and length dimension that is greater than one, and a thickness of 50 millimeters or more, a compressive modulus and tensile modulus in the thickness dimension that is greater than 35 mega pascals and an average shear modulus between its thickness/width and thickness/length dimensions that is greater than sixteen mega pascals.
5 Assignments
0 Petitions
Accused Products
Abstract
Prepare extruded thermoplastic polymer foam by preparing a foamable polymer mixture containing thermoplastic polymer and blowing agent at a mixing pressure, cooling the foamable polymer mixture and extruding it through a foaming die at a die pressure at least 90 bars lower than the mixing pressure and out through a die opening having cross sectional dimensions of 2.5 millimeter or more and a cross sectional area of at least 700 square millimeters at a flow rate greater than 500 kilograms per hour and allow it to expand into a polymer foam between shaping elements while restraining the extrusion rate with a restraining device so as to form polymer foam having 96 volume percent or less void volume, anisotropic cell size, a thickness of 50 millimeter or greater, compressive and tensile moduli in the thickness dimension greater than 35 mega pascals and an average shear modulus greater than 16 mega pascals.
9 Citations
12 Claims
-
1. An extrusion foam process, the process comprising preparing at a mixing pressure a foamable polymer mixture comprising a thermoplastic polymer and a blowing agent, cooling the foamable polymer mixture and extruding it in an extrusion direction through a foaming die at a die pressure and out of the foaming die through a die opening at a flow rate into an atmosphere of low enough pressure to allow the foamable polymer mixture to expand into a polymer foam while traveling in the extrusion direction at an extrusion rate, the extrusion foam process being further characterized by:
-
a. the die pressure being at least 90 bars lower than the mixing pressure; b. all cross sectional dimensions of the die opening being at least 2.5 millimeters and the cross sectional area of the die opening being at least 700 square millimeters; c. the flow rate of the foamable polymer mixture through the die opening being greater than 500 kilograms per hour; d. the foamable polymer mixture expands between restraining elements positioned immediately after the foaming die; e. a device positioned after the restraining elements that restrains the extrusion rate of the polymer foam relative to its unrestrained extrusion rate; and wherein the polymer foam characterized by having a continuous thermoplastic polymer matrix defining cells therein, a void volume of 96 volume percent or less based on total polymer foam volume, a cell size dimensional ratio in the polymer foam thickness dimension to its width and length dimension that is greater than one, and a thickness of 50 millimeters or more, a compressive modulus and tensile modulus in the thickness dimension that is greater than 35 mega pascals and an average shear modulus between its thickness/width and thickness/length dimensions that is greater than sixteen mega pascals. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
-
-
9. An extruded thermoplastic polymer foam comprising a continuous thermoplastic polymer matrix defining cells therein and characterized by having a void volume of 96 percent or less based on total polymer foam volume, a cell size dimensional ratio in the polymer foam thickness dimension to any orthogonal polymer foam dimension that is greater than one;
- a thickness of 50 millimeters or more;
a compressive modulus and tensile modulus in the thickness dimension that is greater than 35 mega pascals and an average shear modulus between thickness/width and thickness/length dimensions that is greater than 16 mega pascals. - View Dependent Claims (10, 11, 12)
- a thickness of 50 millimeters or more;
Specification