Article of footwear with coffee grinds

1. A method for forming an article of footwear, comprising:

fabricating a mixture of polyurethane (PU) precursors and coffee grounds of a selected grind group using a two-step mixing, wherein using the two-step mixing includes a second step, executed after a first step, of further mixing the PU precursors with the coffee grounds in an agitation tank fitted with at least two impellers;

transferring the mixture from the agitation tank to a direct soling instrument and mixing the mixture with other PU precursors to form a foam in a mixing chamber of the direct soling instrument; and

injection molding one or more components of the article of footwear onto another component of the article of footwear using the mixture, the one or more components of the article of footwear formed of a coffee grounds-PU composite material.

2. The method of claim 1 , wherein using the two-step mixing includes a first step of combining the PU precursors with dried coffee grounds of the selected grind group in a container and mixing the PU precursors with the coffee grounds using a mechanical mixer including a mixing head.

3. The method of claim 2 , wherein the mixing head is a rotating helix and rotation of the mixing head is driven by a motor.

4. The method of claim 1 , wherein mixing the PU precursors with the coffee grounds in the agitation tank includes pushing the mixture upwards within the agitation tank via rotation of one of the at least two impellers and pushing the mixture downwards within the agitation tank via rotation of the other of the at least two impellers.

5. The method of claim 1 , wherein injection molding includes transferring the mixture to the mixing chamber via a valve, the valve having a nozzle with an aperture of at least 3 mm.

6. The method of claim 5 , wherein injection molding includes placing the another component of the article of footwear above or below a cavity of a mold and injecting the mixture from the mixing chamber into the mold to form the one or more components of the article of footwear directly above or below the another component of the article of footwear.

7. The method of claim 1 , wherein injection molding the one or more components of the article of footwear onto the another component of the article of footwear includes injection molding a midsole and a toe cap onto an upper part of the article of footwear.

8. The method of claim 1 , further comprising drying the coffee grounds via sunlight and/or a source of heat prior to fabricating the mixture of the PU precursors and the coffee grounds.

9. The method of claim 8 , further comprising sorting the dried coffee grounds into at least three distinct grind groups and then fabricating separate batches of coffee grounds-PU composites with one distinct size of the coffee grounds.

10. A method for forming a midsole of a footwear, comprising:

drying coffee grounds;

sorting the dried coffee grounds into size groups according to grind;

mixing an amount of the dried coffee grounds of at least one of the size groups with chemical precursors of polyurethane (PU) using each of a mechanical mixer and an agitation tank, the agitation tank including at least two impellers; and

injection molding the midsole of the footwear with a coffee grounds-PU composite formed from the dried coffee grounds and the chemical precursors of the PU via a direct soling instrument fitted with a valve having an aperture corresponding to a maximum size of the dried coffee grounds.

11. The method of claim 10 , wherein injecting molding the midsole includes maintaining a consistent flow of the coffee grounds-PU composite by selecting a diameter of the aperture based on a largest size group of the dried coffee grounds used for mixing, and wherein the valve has one or fixed or adjustable aperture.

12. The method of claim 10 , wherein sorting the dried coffee grounds into the size groups includes sorting the dried coffee grounds according to a first size group of less than 2 sq. mm and greater than or equal to 1 sq. mm, a second size group of less than 1 sq. mm and greater than or equal to 0.5 sq. mm, and a third size group of less than 0.5 sq. mm.

13. The method of claim 10 , wherein mixing the amount of the dried coffee grounds with the chemical precursors of the PU includes mixing 3% to 5% by weight of the dried coffee grounds in the coffee grounds-PU composite.

14. The method of claim 10 , wherein mixing using the agitation tank includes agitating the dried coffee grounds and the chemical precursors of the PU in the agitation tank with one of the at least two impellers positioned proximate to a top of the agitation tank and another of the at least two impellers positioned proximate to a bottom of the agitation tank.

15. A method for forming an article of footwear, comprising:

fabricating a mixture of polyurethane (PU) precursors and coffee grounds of a selected grind group using a two-step mixing; and

injection molding one or more components of the article of footwear onto another component of the article of footwear using the mixture, the one or more components of the article of footwear formed of a coffee grounds-PU composite material, and wherein injection molding the one or more components of the article of footwear onto the another component of the article of footwear includes injection molding a midsole and a toe cap onto an upper part of the article of footwear.