Method for making structural foam profiles

Claim 1

A METHOD FOR MAKING CONTINOUS LENGTHS OF RESIN PROFILES FROM THERMOPLASTIC RESIN MATERIAL CONTAINING A HEAT SENSITIVE FOAMING OR EXPANDING AGENT, COMPRISING DELIVERING THE RESIN MATERIAL UNDER PRESSURE THROUGH AND OUT OF A CONFINING PASSAGE INTO AN UNCONFINED ZONE OF LOWER PRESSURE, THE TEMPERATURE AND PRESSURE OF THE RESIN MATERIAL IN THE CONFINING PASSAGE PROVIDING A SOFTENED BUT UNEXPECTED CONDITION OF THE RESIN MATERIAL THEREIN AND THE PRESSURE OF THE RESIN MATERIAL IN THE UNCONFINED ZONE PROCIDING FOR PARTIAL EXPANSION OF THE RESIN MATERIAL BY THE ACTION OF THE FOAMING AGENT, DELIVERING THE EXPANDED RESIN MATERIAL FROM THE UNCONFINED ZONE INTO A SHAPING DIE PASSAGE HAVING CROSS SECTIONAL DIMENSIONS THE SAME AS THOSE OF THE PROFILE BEING MADE AND IN WHICH SAID CROSS SECTIONAL DIMENSIONS ARE UNIFORM THROUGHOUT A SUBSTANTIAL LENGTH OF THE DIE PASSAGE, SOLIDIFYING THE SURFACE LAYER OF THE PREVIOUSLY SOFTENED AND NOW EXPANDED RESIN MATERIAL WHILE IT IS IN THE SHAPING DIE PASSAGE BY COOLING THE SURFACE LAYER OF THE RESIN MATERIAL IN THE SHAPING DIE PASSAGE TO A TEMPERATURE BELOW THE SOFTENING POINT AND APPLYING AXIAL TENSION TO THE EXTRUDED MATERIAL IN THE DIE PASSAGE BY GRIPPING THE RESULTANT SHAPED PROFILE DOWNSTREAM OF THE DIE PASSAGE AND PULLING ON THE PROFILE TO ADVANCE THE RESIN MATERIAL FROM SAID UNCONFINED ZONE INTO AND THROUGH THE DIE PASSAGE IN SLIDING SURFACE CONTACT WITH THE DIE PASSAGE THE RATE OF DELIVERY OF THE RESIN MATERIAL OUT OF THE CONFINING PASSAGE INTO THE UNCONFINED ZONE BEING SUFFICIENT TO MAINTAIN A MASS OF PARTIALLUY EXPANDED RESIN MATERIAL IN SAID ZOONE WHICH MASS IS OF LARGER CROSS SECTIONAL AREA THEN THE DIE PASSAGE, AND THE RATE OF PULLING OF THE RESIN MATERIAL FROM THE UNCONFINED ZONE INTO THE DIE PASSAGE BEING SUFFICIENT TO ADVANCE THE RESIN MATERIAL INTO THE DIE PASSAGE BEFORE THE ESIN MATERIAL IS FULLY EXPANDED AND THEREBY PROVIDE FOR SOLIDIFYING OF THE SURFACE LAYER WHILE IN CONTACT WITH THE SURFACE OF THE SHAPING DIE PASSAGE UNDER RADIAL PRESSURE DEVELOPED BY FOAMING OF THE FOAMING AGENT IN THE INTERIOR PORTION OF THE MATERIAL AND THUS EFFECT FORMATION OF A PROFILE HAVING THE CROSS SECTIONAL DIMENSIONS OF THE DIE PASSAGE AND HAVING A DENSE SKIN AND EXPANDED CORE.

Claim 2

A METHOD FOR MAKING CONTINOUS LENGTHS OF RESIN PROFILES FROM THERMOPLASTIC RESIN MATERIAL CONTAINING A HEAT SENSITIVE FOAMING OR EXPANDING AGENT, COMPRISING DELIVERING THE RESIN MATERIAL UNDER PRESSURE THROUGH AND OUT OF A CONFINING PASSAGE INTO AN UNCONFINED ZONE OF LOWER PRESSURE, THE TEMPERATURE AND PRESSURE OF THE RESIN MATERIAL IN THE CONFINING PASSAGE PROVIDING A SOFTENED BUT UNEXPECTED CONDITION OF THE RESIN MATERIAL THEREIN AND THE PRESSURE OF THE RESIN MATERIAL IN THE UNCONFINED ZONE PROCIDING FOR PARTIAL EXPANSION OF THE RESIN MATERIAL BY THE ACTION OF THE FOAMING AGENT, DELIVERING THE EXPANDED RESIN MATERIAL FROM THE UNCONFINED ZONE INTO A SHAPING DIE PASSAGE HAVING CROSS SECTIONAL DIMENSIONS THE SAME AS THOSE OF THE PROFILE BEING MADE AND IN WHICH SAID CROSS SECTIONAL DIMENSIONS ARE UNIFORM THROUGHOUT A SUBSTANTIAL LENGTH OF THE DIE PASSAGE, SOLIDIFYING THE SURFACE LAYER OF THE PREVIOUSLY SOFTENED AND NOW EXPANDED RESIN MATERIAL WHILE IT IS IN THE SHAPING DIE PASSAGE BY COOLING THE SURFACE LAYER OF THE RESIN MATERIAL IN THE SHAPING DIE PASSAGE TO A TEMPERATURE BELOW THE SOFTENING POINT AND APPLYING AXIAL TENSION TO THE EXTRUDED MATERIAL IN THE DIE PASSAGE BY GRIPPING THE RESULTANT SHAPED PROFILE DOWNSTREAM OF THE DIE PASSAGE AND PULLING ON THE PROFILE TO ADVANCE THE RESIN MATERIAL FROM SAID UNCONFINED ZONE INTO AND THROUGH THE DIE PASSAGE IN SLIDING SURFACE CONTACT WITH THE DIE PASSAGE THE RATE OF DELIVERY OF THE RESIN MATERIAL OUT OF THE CONFINING PASSAGE INTO THE UNCONFINED ZONE BEING SUFFICIENT TO MAINTAIN A MASS OF PARTIALLUY EXPANDED RESIN MATERIAL IN SAID ZOONE WHICH MASS IS OF LARGER CROSS SECTIONAL AREA THEN THE DIE PASSAGE, AND THE RATE OF PULLING OF THE RESIN MATERIAL FROM THE UNCONFINED ZONE INTO THE DIE PASSAGE BEING SUFFICIENT TO ADVANCE THE RESIN MATERIAL INTO THE DIE PASSAGE BEFORE THE ESIN MATERIAL IS FULLY EXPANDED AND THEREBY PROVIDE FOR SOLIDIFYING OF THE SURFACE LAYER WHILE IN CONTACT WITH THE SURFACE OF THE SHAPING DIE PASSAGE UNDER RADIAL PRESSURE DEVELOPED BY FOAMING OF THE FOAMING AGENT IN THE INTERIOR PORTION OF THE MATERIAL AND THUS EFFECT FORMATION OF A PROFILE HAVING THE CROSS SECTIONAL DIMENSIONS OF THE DIE PASSAGE AND HAVING A DENSE SKIN AND EXPANDED CORE.

Claim 7

A method for making continuous lengths of resin profiles from softened thermoplastic resin material containing a foaming or expanding agent, comprising delivering the resin material under pressure through and out of a confining passage into an unconfined zone of lower pressure, the temperature and pressure of the resin material in the confining passage providing a softened but unexpanded condition of the resin material therein and the pressure of the resin material in the unconfined zone providing for expansion of the resin material, delivering the expanded resin material from the unconfined zone into a shaping die passage having cross sectional dimensions the same as those of the profile being made and in which said cross sectional dimensions are uniform throughout a substantial length of the die passage, the die passage having its delivery end submerged in a water bath, solidifying the surface layer of the previously softened and now expanded resin material while it is in the shaping die passage by cooling the surface layer of the resin material in the entrance end portion of the die passage to a temperature below the softening point, and applying axial tension to the expanded material in the die passage by gripping the resultant shaped profile downstream of the water bath and pulling on the profile to advance the resin material from said unconfined zone into the die passage.

Claim 8

A method for making continuous lengths of resin profiles from softened thermoplastic resin material containing a foaming or expanding agent, comprising delivering the resin material under pressure through and out of a confining passage into an unconfined zone of lower pressure, the temperature and pressure of the resin material in the confining passage providing a softened but unexpanded condition of the resin material therein and the pressure of the resin material in the unconfined zone providing for expansion of the resin material, delivering the expanded resin material from the unconfined zone into a shaping die passage having cross sectional dimensions the same as those of the profile being made and in which said cross sectional dimensions are uniform throughout a substantial length of the die passage, the die passage having its delivery end submerged in a water bath, solidifying the surface layer of the previously softened and now expanded resin material while it is in the shaping die passage by cooling the surface layer of the resin material in the entrance end portion of the die passage to a temperature below the softening point, and applying axial tension to the expanded material in the die passage by gripping the resultant shaped profile downstream of the water bath and pulling on the profile to advance the resin material from said unconfined zone into the die passage.

Claim 10

A method for making continuous lengths of resin profiles from softened thermoplastic resin material containing a foaming or expanding agent, comprising delivering the resin material under pressure through and out of a confining passage into an unconfined zone of lower pressure, the temperature and pressure of the resin material in the confining passage providing a softened but unexpanded condition of the resin material therein and the pressure of the resin material in the unconfined zone providing for expansion of the resin material to develop an enlarged mass of the resin material, delivering the unexpanded resin material from the unconfined zone into a shaping die passage, solidifying the surface layer of the previously softened and now expanded resin material while it is in the shaping die passage by cooling the surface layer of the resin material in the die passage to a temperature below the softening point and thereby provide a die shaped profile having a dense skin and expanded core, applying axial tension to the expanded material in the die passage by gripping the resultant shaped profile downstream of the die and pulling on the profile to advance the resin material from said unconfined zone into the die passage, and regulating the rate of advancement of the resin material from said unconfined zone into the die passage in accordance with the size of the mass of resin material in the unconfined zone, the control providing for maintenance of a mass of cross sectional larger than the cross section of the die passage.

Claim 11

A method for making continuous lengths of resin profiles from softened thermoplastic resin material containing a foaming or expanding agent, comprising delivering the resin material under pressure through and out of a confining passage into an unconfined zone of lower pressure, the temperature and pressure of the resin material in the confining passage providing a softened but unexpanded condition of the resin material therein and the pressure of the resin material in the unconfined zone providing for expansion of the resin material to develop an enlarged mass of the resin material, delivering the unexpanded resin material from the unconfined zone into a shaping die passage, solidifying the surface layer of the previously softened and now expanded resin material while it is in the shaping die passage by cooling the surface layer of the resin material in the die passage to a temperature below the softening point and thereby provide a die shaped profile having a dense skin and expanded core, applying axial tension to the expanded material in the die passage by gripping the resultant shaped profile downstream of the die and pulling on the profile to advance the resin material from said unconfined zone into the die passage, and regulating the rate of advancement of the resin material from said unconfined zone into the die passage in accordance with the size of the mass of resin material in the unconfined zone, the control providing for maintenance of a mass of cross sectional larger than the cross section of the die passage.

Claim 12

A method for making continuous lengths of resin profiles from softened thermoplastic resin material containing a foaminG or expanding agent, comprising delivering the resin material under pressure through and out of an annular confining passage into an unconfined zone of lower pressure, the temperature and pressure of the resin material in the confining passage providing a softened but unexpanded condition of the resin material therein and the pressure of the resin material in the unconfined zone providing for expansion of the resin material, delivering the expanded resin material from the unconfined zone into an annular shaping die passage, solidifying the inside and outside surface layers of the previously softened and now expanded resin material while it is in the die passage by cooling the inside and outside surface layers of the resin material in the die passage to a temperature below the softening point and thereby provide a die shaped tubular profile having an expanded core with a dense skin at the inside and outside surfaces, and applying axial tension to the expanded material in the die passage by gripping the resultant shaped profile downstream of the die and pulling on the profile to advance the resin material from said unconfined zone into the die passage.

Claim 13

A method for making continuous lengths of resin profiles from softened thermoplastic resin material containing a foaminG or expanding agent, comprising delivering the resin material under pressure through and out of an annular confining passage into an unconfined zone of lower pressure, the temperature and pressure of the resin material in the confining passage providing a softened but unexpanded condition of the resin material therein and the pressure of the resin material in the unconfined zone providing for expansion of the resin material, delivering the expanded resin material from the unconfined zone into an annular shaping die passage, solidifying the inside and outside surface layers of the previously softened and now expanded resin material while it is in the die passage by cooling the inside and outside surface layers of the resin material in the die passage to a temperature below the softening point and thereby provide a die shaped tubular profile having an expanded core with a dense skin at the inside and outside surfaces, and applying axial tension to the expanded material in the die passage by gripping the resultant shaped profile downstream of the die and pulling on the profile to advance the resin material from said unconfined zone into the die passage.

Claim 15

A method for making continuous lengths of resin profiles from thermoplastic resin material containing a foaming or expanding agent, comprising heating the resin material sufficiently to soften the resin material to flowable condition, delivering the softened resin material under pressure through and out of a confining passage into an unconfined zone of lower pressure, the temperature and pressure of the resin material in the confining passage maintaining a softened but unexpanded condition of the resin material therein and the pressure of the resin material in the unconfined zone providing for partial expansion of the resin material under action of the foaming agent, delivering the partially expanded resin material from the unconfined zone into a shaping die passage having cross sectional dimensions the same as those of the profile being made and in which said cross sectional dimensions are uniform throughout a substantial length of the die passage, delivering the profile from the shaping die passage through a water bath, solidifying the surface layer of the previously softened resin material while it is in the shaping die passage by cooling the surface layer of the resin material in the entrance end portion of the die passage to a temperature below the softening point, applying axial tension to the expanded material in the die passage by gripping the resultant shaped profile downstream of the water bath and pulling on the profile to advance the resin material from said unconfined zone into the die passage, and effecting flow of water along the surface of the profile in the die passage in a direction upstream of advancement of the profile, while the profile is being advanced through the die passage.

Claim 16

A method for making continuous lengths of resin profiles from thermoplastic resin material containing a foaming or expanding agent, comprising heating the resin material sufficiently to soften the resin material to flowable condition, delivering the softened resin material under pressure through and out of a confining passage into an unconfined zone of lower pressure, the temperature and pressure of the resin material in the confining passage maintaining a softened but unexpanded condition of the resin material therein and the pressure of the resin material in the unconfined zone providing for partial expansion of the resin material under action of the foaming agent, delivering the partially expanded resin material from the unconfined zone into a shaping die passage having cross sectional dimensions the same as those of the profile being made and in which said cross sectional dimensions are uniform throughout a substantial length of the die passage, delivering the profile from the shaping die passage through a water bath, solidifying the surface layer of the previously softened resin material while it is in the shaping die passage by cooling the surface layer of the resin material in the entrance end portion of the die passage to a temperature below the softening point, applying axial tension to the expanded material in the die passage by gripping the resultant shaped profile downstream of the water bath and pulling on the profile to advance the resin material from said unconfined zone into the die passage, and effecting flow of water along the surface of the profile in the die passage in a direction upstream of advancement of the profile, while the profile is being advanced through the die passage.

Claim 17

A method for making continuous lengths of resin profiles from thermoplastic resin material containing a foaming or expanding agent, comprising heating the resin material sufficiently to soften the resin material to flowable condition, delivering the softened resin material under pressure through and out of a confining passage into an unconfined zone of lower pressure, the temperature and pressure of the resin material in the confining passage maintaining a softened but unexpanded condition of the resin material therein and the pressure of the resin material in the unconfined zone providing for partial expansion of the resin material under action of the foaming agent, delivering the partially expanded resin material from the unconfined zone into a shaping die passage having cross sectional dimensions the same as those of thE profile being made and in which said cross sectional dimensions are uniform throughout a substantial length of the die passage, solidifying the surface layer of the previously softened resin material while it is in the shaping die passage by cooling the surface layer of the resin material in the entrance end portion of the die passage to a temperature below the softening point, applying axial tension to the expanded material in the die passage by gripping the resultant shaped profile downstream of the shaping die passage and pulling on the profile to advance the resin material from said unconfined zone into and through the die passage, and regulating the pulling and thus the rate of advancement of the profile in accordance with the cross sectional area of the mass of resin material in the unconfined zone, the regulation providing for maintenance of a mass of cross sectional area greater than that of the shaping die passage.

Claim 18

A method for making continuous lengths of resin profiles from thermoplastic resin material containing a foaming or expanding agent, comprising heating the resin material sufficiently to soften the resin material to flowable condition, delivering the softened resin material under pressure through and out of a confining passage into an unconfined zone of lower pressure, the temperature and pressure of the resin material in the confining passage maintaining a softened but unexpanded condition of the resin material therein and the pressure of the resin material in the unconfined zone providing for partial expansion of the resin material under action of the foaming agent, delivering the partially expanded resin material from the unconfined zone into a shaping die passage having cross sectional dimensions the same as those of thE profile being made and in which said cross sectional dimensions are uniform throughout a substantial length of the die passage, solidifying the surface layer of the previously softened resin material while it is in the shaping die passage by cooling the surface layer of the resin material in the entrance end portion of the die passage to a temperature below the softening point, applying axial tension to the expanded material in the die passage by gripping the resultant shaped profile downstream of the shaping die passage and pulling on the profile to advance the resin material from said unconfined zone into and through the die passage, and regulating the pulling and thus the rate of advancement of the profile in accordance with the cross sectional area of the mass of resin material in the unconfined zone, the regulation providing for maintenance of a mass of cross sectional area greater than that of the shaping die passage.