KR-20260062186-A - Eco-friendly insole with a multi-layer structure

Abstract

The present invention relates to a shoe insole composed of a plurality of layers having different coffee grounds content and cell structures. To this end, an eco-friendly shoe insole having a multilayer structure according to the present invention comprises an upper layer having an open cell structure comprising 25 to 30 parts by weight of coffee grounds powder and 70 to 75 parts by weight of thermoplastic polyurethane (TPU); a middle layer having an open cell structure and a closed cell structure comprising 20 to 25 parts by weight of coffee grounds powder and 75 to 80 parts by weight of thermoplastic polyurethane (TPU); and a lower layer having a closed cell structure comprising 15 to 20 parts by weight of coffee grounds powder and 80 to 85 parts by weight of thermoplastic polyurethane (TPU).

Inventors

• 양지민

Assignees

• 양지민

Dates

Publication Date

20260507

Application Date

20241025

Claims (3)

1. An upper layer having an open-cell structure comprising 25 to 30 parts by weight of coffee grounds powder and 70 to 75 parts by weight of thermoplastic polyurethane (TPU), and An intermediate layer having an open-cell structure and a closed-cell structure comprising 20 to 25 parts by weight of coffee grounds powder and 75 to 80 parts by weight of thermoplastic polyurethane (TPU), An eco-friendly shoe insole having a multilayer structure comprising a lower layer having a closed-cell structure comprising 15 to 20 parts by weight of coffee grounds powder and 80 to 85 parts by weight of thermoplastic polyurethane (TPU).
2. In paragraph 1, The upper layer comprises a wetting agent including at least one of glycerin and sodium lauryl sulfate (SLS), and An eco-friendly shoe insole having a multilayer structure characterized by containing a thickener comprising at least one of starch and gelatin.
3. A step of manufacturing an upper layer by placing a first coffee grounds paste, composed of 25 to 30 parts by weight of coffee grounds powder and 70 to 75 parts by weight of thermoplastic polyurethane (TPU), into a press mold, adding a foaming agent, and then compression molding with a press; A step of manufacturing an intermediate layer by placing a second coffee grounds dough, composed of 20 to 25 parts by weight of coffee grounds powder and 75 to 80 parts by weight of thermoplastic polyurethane (TPU), into a press mold and compression molding it with a press without a foaming agent, and then placing the second coffee grounds dough again, adding a foaming agent, and compression molding it with a press; A method for manufacturing an eco-friendly shoe insole having a multilayer structure, comprising the step of placing a third coffee grounds paste, composed of 15 to 20 parts by weight of coffee grounds powder and 80 to 85 parts by weight of thermoplastic polyurethane (TPU), into a press mold and compression molding it with a press without a foaming agent to produce a lower layer.

Description

Eco-friendly shoe insole with a multi-layer structure The present invention relates to a shoe insole composed of a plurality of layers with different coffee grounds content and cell structures. When engaging in activities for a long time while wearing shoes, there is a problem in that sweat from the feet mixes with foreign substances and decomposes due to stagnant internal air, causing bacteria to multiply inside the shoes and resulting in a severe odor. Attempts are being made to add deodorizing and antibacterial functions to shoe insoles to reduce bacterial growth and odor generation inside the shoes. A representative example is the use of coffee grounds, an eco-friendly material, to make insoles. Coffee grounds are a waste product that is discarded in large quantities worldwide, and they are used in the manufacture of shoe insoles due to their antibacterial, deodorizing, and moisture-regulating properties. However, conventional coffee grounds shoe insoles are manufactured with a single-layer structure about 2mm thick, lacking functionality such as shock absorption or pressure dispersion. Meanwhile, conventional shoe insoles are made of a polyurethane open-cell structure about 4mm thick, which provides excellent breathability but is excessively soft, causing unnecessary force to be applied to the toes and ankles when walking. FIG. 1 is a drawing showing a shoe insole according to the present invention. FIG. 2 is a side cross-sectional view of a shoe insole according to the present invention. The objects, specific advantages, and novel features of the present invention will become more apparent from the following detailed description and preferred embodiments in conjunction with the accompanying drawings. The terms used are defined with consideration of their functions in the present invention, and these may vary depending on the intent or convention of the user or a person skilled in the relevant technical field. Therefore, the definitions of these terms should be based on the content throughout this specification. Coffee grounds powder production Since coffee grounds have a high moisture content, a heat drying process is required. The moisture content of the coffee grounds must be less than 3%, and molding is impossible if it exceeds this amount. To do this, coffee grounds are heated to a temperature of 100 to 150°C for about 2 to 3 hours to dry them, and the dried coffee grounds are ground to 200 to 300 mesh to produce coffee grounds powder with fine particles. Manufacturing process of multi-layered shoe insoles The eco-friendly shoe insole having a multilayer structure according to the present invention is composed of an upper layer, an intermediate layer, and a lower layer. The upper layer, which comes into direct contact with the sole of the foot, adopts an open-cell structure to maximize breathability and odor removal. This open-cell structure efficiently dissipates heat and moisture generated from the sole, absorbs shock, and enhances comfort. The middle layer primarily performs shock absorption and pressure distribution functions; by combining open-cell and closed-cell structures, it optimizes shock absorption performance while dispersing pressure applied to the foot and effectively absorbing impact energy. The closed-cell structure complements the flexibility of the open-cell design, providing stable support for the toes and the entire foot, and maintains durability even during prolonged wear. The middle layer is designed to efficiently cushion the impact generated when walking by making the heel and midfoot thicker than other layers. The sublayer provides support and stability to the toes and forefoot. Utilizing a closed-cell structure, it enhances rigidity and durability, while its high density ensures stable support for the foot. This sublayer reduces toe fatigue, exhibits minimal deformation even with prolonged wear, and maintains foot balance without loss of support. 1) Manufacturing of the upper layer 25 to 30 parts by weight of the coffee grounds powder prepared above and 70 to 75 parts by weight of thermoplastic polyurethane (TPU) are placed in a mixer and mixed to make a coffee grounds paste. Thermoplastic polyurethane (TPU) is widely used in a wide range of fields because it has superior low-temperature properties and high flexibility compared to other resins, good durability and wear resistance, excellent mechanical properties such as tensile strength, elongation, and fatigue resistance, and excellent flexural resistance, cold resistance, and oil resistance. Here, if the coffee grounds contain 30 parts by weight or more, the mechanical strength decreases, and if they contain 25 parts by weight or less, the mechanical strength increases but the deodorizing and dehumidifying functions decrease. Meanwhile, when making the coffee grounds paste, a wetting agent or a thickening agent may be added. Humectants perform the function of assisting shoe insoles in effectively absorbing moisture or