Methods for forming footwear using recycled plastics
Presented are manufacturing systems, methods, and devices for forming footwear using scrap or waste plastic materials. A method for manufacturing an article of footwear, such as an athletic shoe, begins with receiving a batch of recycled plastic, which may include thermoplastic elastomers or ethylene-vinyl acetate, and grinding the batch of recycled plastic material. The ground recycled material is processed, for example, by adding a foaming agent that activates at elevated temperatures. The processed recycled material is placed into the internal cavity of a final mold that is shaped like a segment of the footwear, such as a unitary sole structure. To form the footwear segment, the processed recycled material is heated past the threshold activation temperature of the foaming agent such that the foaming agent causes the recycled material to expand and fill the internal cavity of the final mold. The formed footwear segment is then extracted from the mold.
1. A method for manufacturing an article of footwear, the method comprising:
receiving recycled plastic material;
grinding the recycled plastic material into ground recycled material;
processing the ground recycled material into processed recycled material, the processing including adding a resin and a foaming agent to the ground recycled material;
placing the processed recycled material into an internal cavity of a final mold, the internal cavity shaped like a footwear segment of the article of footwear, wherein placing the processed recycled material into the internal cavity includes:
forming a preform of the processed recycled material,
scattering a first portion of the ground recycled material around the internal cavity of the final mold, and
placing the preform into the internal cavity of the final mold;
forming the footwear segment including heating the processed recycled material past a threshold activation temperature of the foaming agent such that the foaming agent causes the processed recycled material to expand and fill the internal cavity of the final mold; and
extracting the formed footwear segment from the final mold.
2. The method of claim 1 , wherein the received recycled plastic material includes scrap and/or waste material comprising thermoplastic elastomer (TPE) plastic and/or ethylene-vinyl acetate (EVA) copolymer plastic.
3. The method of claim 1 , wherein the received recycled plastic material comprises a butadiene rubber.
4. The method of claim 1 , wherein forming the footwear segment further includes compression molding or injection molding the processed recycled material in the final mold.
5. The method of claim 1 , further comprising;
preforming virgin polymer material into a virgin plastic preform; and
prior to forming the footwear segment, placing the virgin plastic preform into the internal cavity of the final mold.
6. The method of claim 1 , wherein forming the processed recycled material into the preform includes compression molding or injection molding the processed recycled material in a preform mold.
7. The method of claim 6 , wherein forming the processed recycled material into the preform further includes adding a composition of virgin polymer material into the preform mold.
8. The method of claim 1 , wherein processing the ground recycled material further includes adding to the ground recycled material a filler, a pigment, a processing aid, and/or a crosslinking agent.
9. The method of claim 1 , further comprising placing a preform of virgin polymer material into the internal cavity of the final mold prior to forming the footwear segment.
10. The method of claim 1 , further comprising, after placing the preform into the internal cavity, scattering a second portion of the ground recycled material on an exposed surface of the preform.
11. The method of claim 1 , wherein the resin includes a polyurethane (PU) base material.
12. The method of claim 1 , wherein the resin includes a virgin synthetic rubber material.
13. The method of claim 1 , wherein the foaming agent includes a diazocarbamide.
14. A method for manufacturing an article of footwear, the method comprising:
receiving recycled plastic material;
grinding the recycled plastic material into ground recycled material;
processing the ground recycled material into processed recycled material, the processing including adding a resin and a foaming agent to the ground recycled material;
placing the processed recycled material into an internal cavity of a final mold, including:
forming a preform of the processed recycled material;
wetting the preform;
placing the wet preform into a container;
placing an amount of ground recycled material into the container;
agitating the container to coat the preform with the ground recycled material; and
placing the preform coated with the ground recycled material into the internal cavity of the final mold;
forming a footwear segment including heating the processed recycled material past a threshold activation temperature of the foaming agent such that the foaming agent causes the processed recycled material to expand and fill the internal cavity of the final mold; and
extracting the formed footwear segment from the final mold.
15. The method of claim 14 , further comprising, prior to placing the preform into the internal cavity, scattering a predefined portion of the ground recycled material around the internal cavity of the final mold.
16. The method of claim 14 , wherein the received recycled plastic material includes scrap and/or waste material comprising thermoplastic elastomer (TPE) plastic and/or ethylene-vinyl acetate (EVA) copolymer plastic.
17. The method of claim 14 , wherein the received recycled plastic material includes a butadiene rubber.
18. The method of claim 14 , wherein forming the footwear segment further includes compression molding or injection molding the processed recycled material in the final mold.
19. The method of claim 14 , wherein forming the processed recycled material into the preform includes compression molding or injection molding the recycled material in a preform mold.
20. The method of claim 19 , wherein forming the processed recycled material into the preform further includes adding a composition of virgin polymer material into the preform mold.
21. The method of claim 14 , wherein processing the ground recycled material further includes adding to the ground recycled material a filler, a pigment, a processing aid, and/or a crosslinking agent.
22. The method of claim 14 , further comprising placing a preform of virgin polymer material into the internal cavity of the final mold prior to forming the footwear segment.
23. The method of claim 14 , wherein the resin includes a polyurethane (PU) base material.
24. The method of claim 14 , wherein the resin includes a virgin synthetic rubber material.
25. The method of claim 14 , wherein the foaming agent includes a diazocarbamide.