Method for production of low density polyester foam and articles made thereof utilizing low I.V. polyester feedstock

A method for producing a polyester foam comprising:

• providing a low intrinsic viscosity raw material, wherein the low intrinsic viscosity raw material includes between 25% to 100% of a post consumer polyester, wherein the low intrinsic viscosity raw material provided has an intrinsic viscosity of less than 0.8 dl/g, wherein the low intrinsic viscosity raw material includes:
• virgin polyester;
• the post consumer polyester is a polyester feedstock that consists of a post-industrial waste resin;
• and
• process regrind;
• wherein the post-industrial waste resin of the low intrinsic viscosity raw material consists of post-consumer scrap bottle flake;
• crystallizing the low intrinsic viscosity raw material in a crystallizer, wherein the crystallizing is configured to prevent the low intrinsic viscosity raw material from melting during a de-condensation reaction;
• increasing the intrinsic viscosity of the low intrinsic viscosity raw material via the de-condensation reaction configured to support foaming, wherein the intrinsic viscosity of the low intrinsic viscosity raw material is increased to 1.1 dl/g or greater including increasing a molecular weight of the low intrinsic viscosity raw material by feeding the low intrinsic viscosity raw material into a solid-state reactor;
• creating a starting formulation including the low intrinsic viscosity raw material with the increased intrinsic viscosity including adding:
• a cross-linking agent configured to fine tune the viscosity of the low intrinsic viscosity raw material;
• and
• a nucleating agent configured for aiding in nucleating the low intrinsic viscosity raw material, wherein the nucleating agent consists of a poly-flouro-ethylene particle;
• foaming the starting formulation to create the polyester foam including tandem extrusion of the starting formulation to create the polyester foam, wherein the tandem extrusion of the starting formulation to create the polyester foam including:
• a primary twin screw extruder including an injection system and a blowing agent storage system configured to introduce a blowing agent into the starting formulation once the starting formulation is melted and mixed via the primary twin screw extruder, whereby a homogenous mixture exits the primary twin screw extruder, wherein the blowing agent consists of a hydrocarbon selected from a group consisting of:
• C5 hydrocarbons;
• and C6 hydrocarbons;
• a secondary cooling extruder configured to cool the homogenous mixture that exits the primary twin screw extruder for giving a necessary rheology needed to the homogenous solution for successful foaming, the secondary cooling extruder is configured to give heat exchange with minimal shear heat generation, the secondary cooling extruder includes a screw configured to act as a heat exchanger for removing heat from the homogenous mixture and increasing viscosity;
• screening for solid impurities via a screen changer between the primary twin screw extruder and the secondary cooling extruder;
• and
• pressurizing the homogenous mixture exiting the primary twin screw extruder via a gear pump between the primary twin screw extruder and the secondary cooling extruder, said gear pump is configured to impart minimal additional shear heat while pressurizing the homogenous mixture;
• forming the polyester foam using a die, wherein the die is a board die or a sheet die configured with associated finishing equipment, wherein the associating finishing equipment including:
• a sizing drum;
• a pull unit;
• and
• a winder configured for creating a roll of the polyester foam;
• wherein the pull unit is configured to pull a bubble of the polyester foam over the sizing drum and slit the bubble to open a flat sheet, wherein the polyester foam is produced as the flat sheet in a roll stock form to a thickness of at least 0.040 inches and of up to 0.375 inches thick;
• wherein the polyester foam is produced with the thicknesses greater than 0.5 inches and widths of greater than 6 inches;
• wherein, the polyester foam produced has a specific gravity of less than 0.65 g/cc.