# US 9,517,583 B2 · Method of forming natural fiber polymer composite > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,517,583 B2 - Document ID: US9517583B2 - Status: Granted - Kind: B2 - Application number: 13/710,540 - Filed: 2012-12-11 - Published: 2014-06-12 - Granted: 2016-12-13 - Earliest claimed: 2012-12-11 - Assignees: Ford Global Technologies, LLC - Applicants: Ford Global Technologies, LLC - Inventors: Ellen Cheng-Chi Lee; Angela Harris - Web page: https://patentgrep.com/patent/US9517583B2 ## CPC - B29C 48/92: Measuring, controlling or regulating - B29C 48/295: in gaseous form - B29C 48/82: Cooling (B29C48/84 takes precedence) - B29C 48/022: {characterised by the choice of material} - B29C 48/278: {of additives or processing aids} - B29C 48/286: {Raw material dosing} - B29C 48/2886: {of fillers or of fibrous materials, e.g. short-fibre reinforcements} - B29C 48/29: in liquid form - B29C 48/297: {at several locations, e.g. using several hoppers or using a separate additive feeding} - B29C 48/834: {Cooling} - B29C 2948/92695: Viscosity; Melt flow index [MFI]; Molecular weight - B29C 2948/92704: Temperature - Y02P 70/10: Greenhouse gas [GHG] capture, material saving, heat recovery or other energy efficient measures, e.g. motor control, characterised by manufacturing processes, e.g. for rolling metal or metal working - B29C: SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING (making preforms B29B11/00; making laminated products by combining previously unconnected layers which become one product whose layers will remain together B32B37/00 - B32B41/00) - Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS ## Abstract A method of forming a natural fiber polymer composite includes the steps of introducing into an extruder a polymer, a natural fiber and a supercritical fluid to form a natural fiber polymer mixture; and extruding the natural fiber polymer mixture to form the natural fiber polymer composite at a temperature below a standard melting temperature of the polymer alone. The supercritical fluid may be introduced after the polymer is introduced into the extruder. The supercritical fluid may be introduced before or after the natural fiber is introduced into the extruder. ## Claims ### Claim 1 A method comprising: (a) introducing a polymer into a first zone of an extruder; (b) melting the polymer in the first zone to form a molten polymer flowing downstream into a second zone of the extruder; (c) introducing a supercritical fluid into the second zone to lower the temperature of the molten polymer flowing downstream into a third zone of the extruder; (d) introducing a natural fiber into the third zone to form a natural fiber polymer mixture at a temperature lower than the melting point of the polymer; and (e) extruding the natural fiber polymer mixture through an exit of the extruder to form a polymer fiber composite having a first color change rating using steps (a), (b) and (d) but not (c) and a second color change rating using steps (a), (b), (c) and (d), the first color change rating represents a stronger visible color shift than the second color change rating. ### Claim 2 (depends on 1) The method of claim 1, wherein the temperature of the natural fiber polymer mixture in the third zone is at least 10° F. lower than the melting point of the polymer. ### Claim 3 (depends on 1) The method of claim 1, wherein the temperature of the natural fiber polymer mixture in the third zone is at least 80° F. lower than the melting point of the polymer. ### Claim 4 (depends on 1) The method of claim 1, wherein the molten polymer in the third zone is cooled with a temperature control device before introducing the natural fiber. ### Claim 5 (depends on 1) The method of claim 1, wherein the supercritical fluid is CO2. ### Claim 6 (depends on 1) The method of claim 1, wherein the polymer is introduced into the first zone in a solid form. ### Claim 7 (depends on 1) The method of claim 1, wherein the weight ratio of the supercritical fluid to the molten polymer in the second zone is no greater than 20%. ### Claim 8 (depends on 1) The method of claim 1, further comprising forming natural fiber polymer pellets from the natural fiber polymer mixture. ### Claim 9 (depends on 1) The method of claim 1, wherein the polymer includes a polyamide polymer. ### Claim 10 (depends on 1) The method of claim 1, wherein the polymer includes at least one of a nylon 6, a nylon 6,6, nylon 6,10 and a nylon 11 polymer. ### Claim 11 (depends on 1) The method of claim 1, wherein the natural fiber includes at least one of cellulose, soy flour and coconut shell powder. ### Claim 12 A method comprising: (a) introducing a near critical fluid into a molten polymer in a first zone of an extruder to lower the temperature of the molten polymer flowing downstream into a second zone of the extruder; and (b) introducing a natural fiber into the molten polymer in the second zone to form a natural fiber polymer mixture at a temperature lower than the melting point of the polymer; and (c) extruding the natural fiber polymer mixture through an exit of the extruder to form a polymer fiber composite having a first color change rating using steps (b) but not (a) and a second color change rating using steps (a) and (b), the first color change rating represents a stronger visible color shift than the second color change rating. ### Claim 13 (depends on 12) The method of claim 12, wherein the second zone is downstream of the first zone. ### Claim 14 (depends on 12) The method of claim 12, further comprising restricting the flow of the near critical fluid into the second zone. ### Claim 15 (depends on 12) The method of claim 12, wherein the molten polymer is polypropylene. ### Claim 16 (depends on 12) The method of claim 12, wherein the temperature of the natural fiber polymer mixture in the third zone is at least 80° F. lower than the melting point of the polymer. ### Claim 17 A method comprising: (a) introducing a polymer into a first zone of an extruder; (b) melting the polymer in the first zone to form a molten polymer flowing downstream into a second zone of the extruder; (c) introducing a supercritical fluid into the second zone to lower the temperature of the molten polymer flowing downstream into a third zone of the extruder; (d) introducing a soy fiber into the third zone to form a natural fiber polymer mixture; and (e) extruding the natural fiber polymer mixture through an exit of the extruder to form a polymer fiber composite having a first color change rating using steps (a), (b) and (d) but not (c) and a second color change rating using steps (a), (b), (c) and (d), the first color change rating represents a stronger visible color shift than the second color change rating. ### Claim 18 (depends on 17) The method of claim 17, wherein the third zone is downstream of the first and second zones. ### Claim 19 (depends on 17) The method of claim 17, wherein the second zone is downstream of the first zone. ### Claim 20 (depends on 17) The method of claim 17, wherein the polymer is polypropylene.