Plastic composite material comprising coffee grounds and method for preparing same, and product using same and characteristics of product

A method for manufacturing a plastic composite material comprising coffee grounds, the method comprising:

• preparing coffee grounds and biomass;
• drying the coffee grounds and the biomass;
• freeze-grinding the dried coffee grounds, wherein the coffee grounds formed by grinding the dried coffee grounds have a particle size distribution of 94% by weight or more for coffee grounds particles with a particle size greater than and 250 μm less than or equal to 850 μm;
• primarily extruding a first mixture obtained by mixing a polymer resin, the ground coffee grounds, the dried biomass, and a first additive;
• secondarily extruding a second mixture obtained by mixing the first extrudate extruded in the primary extrusion process and a second additive;
• and
• drying the second extrudate extruded in the secondary extrusion process.