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).

Description

Technology Field

[0001] The present invention relates to a shoe insole composed of a plurality of layers with different coffee grounds content and cell structures. Background Technology

[0002] 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.

[0003] Attempts are being made to add deodorizing and antibacterial functions to shoe insoles to reduce bacterial growth and odor generation inside the shoes.

[0004] 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.

[0005] 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.

[0006] 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. Prior art literature

[0007] (Prior Art 1) Korean Published Patent No. 10-2018-0093644 The problem to be solved

[0008] The present invention was devised to solve the above-mentioned problems, and the objective of the present invention is to provide an eco-friendly shoe insole that uses coffee grounds to improve not only the odor removal function but also the functions of shock absorption, pressure distribution, and toe support. means of solving the problem

[0009] To this end, the 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), 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), 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).

[0010] Here, the upper layer is characterized by comprising a wetting agent comprising at least one of glycerin and sodium lauryl sulfate (SLS), and a thickening agent comprising at least one of starch and gelatin.

[0011] In addition, the method for manufacturing an eco-friendly shoe insole having a multilayer structure according to the present invention comprises the steps 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; manufacturing an intermediate layer by placing a second coffee grounds paste 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 with a press without a foaming agent, and then placing the second coffee grounds paste again, adding a foaming agent, and then compression molding with a press; and manufacturing a lower layer by 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 then compression molding with a press without a foaming agent. Effects of the invention

[0012] As described above, the present invention has the effect of improving not only environmental benefits but also functional performance by applying a multi-layer structure to a shoe insole, varying the cell structure according to the function of each layer of the insole, and applying coffee grounds at a weight ratio of 15% to 30% to provide an optimized content.

[0013] In other words, the shoe insole according to the present invention can provide users with an eco-friendly product that protects foot health by exhibiting various functions such as shock absorption, pressure dispersion, toe support, and odor removal, thereby securing competitiveness as a functional eco-friendly product in the market. Brief explanation of the drawing

[0014] 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. Specific details for implementing the invention

[0015] 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.

[0016] 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.

[0018] Coffee grounds powder production

[0019] 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.

[0020] 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.

[0022] Manufacturing process of multi-layered shoe insoles

[0023] 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.

[0024] 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.

[0025] 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.

[0026] The middle layer is designed to efficiently cushion the impact generated when walking by making the heel and midfoot thicker than other layers.

[0027] 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.

[0029] 1) Manufacturing of the upper layer

[0030] 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.

[0031] 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.

[0032] 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.

[0033] Meanwhile, when making the coffee grounds paste, a wetting agent or a thickening agent may be added.

[0034] Humectants perform the function of assisting shoe insoles in effectively absorbing moisture or sweat from the feet. Glycerin, sodium lauryl sulfate (SLS), etc., may be used as humectants.

[0035] Thickeners are additives used to control the texture and shape of products by increasing the viscosity of materials, and they can enhance product stability and provide uniform performance. Starch and gelatin may be used as thickeners.

[0036] The above coffee grounds paste is placed into a press mold, and a suitable foaming agent (water, carbon dioxide, etc.) is added. Then, by compression molding with a press having a temperature of 100 to 180°C, an upper layer having an open-cell structure is produced.

[0038] 2) Preparation of intermediate layer

[0039] 20 to 25 parts by weight of the coffee grounds powder prepared above and 75 to 80 parts by weight of thermoplastic polyurethane (TPU) are placed in a mixer and mixed to make a coffee grounds paste.

[0040] If the coffee grounds contain 25 parts by weight or more, the shock absorption and pressure dispersion functions may be reduced, and if they contain 20 parts by weight or less, the deodorizing and dehumidifying functions exhibited in the multilayer structure may be somewhat reduced.

[0041] The above coffee grounds paste is placed into a press mold and compressed into a press having a temperature of 80 to 160°C without a foaming agent to create a closed-cell structure, and then the coffee grounds paste is placed again on the closed-cell structure, a suitable foaming agent is added, and then compressed into a press having a temperature of 100 to 180°C to produce an intermediate layer having a combination of an open-cell structure and a closed-cell structure.

[0043] 3) Sublayer manufacturing

[0044] 15 to 20 parts by weight of the coffee grounds powder prepared above and 80 to 85 parts by weight of thermoplastic polyurethane (TPU) are placed in a mixer and mixed to make a coffee grounds paste.

[0045] If the coffee grounds contain 20 parts by weight or more, the foot support function and stability decrease, and if they contain 15 parts by weight or less, the deodorizing and dehumidifying functions exhibited in the multilayer structure may decrease somewhat.

[0046] The above coffee grounds paste is placed into a press mold and compressed with a press having a temperature of 100 to 180°C without a foaming agent to produce a lower layer having a closed-cell structure.

[0048] 4) Manufacture of multi-layered insoles

[0049] Once the upper layer, middle layer, and lower layer are each made, an adhesive is applied between each layer, and then the three layers are bonded together to produce a multi-layered insole.

[0050] As described above, by varying the coffee grounds content in each of the three layers and providing structural differentiation, it simultaneously offers multifunctionality (shock absorption, support, breathability) that is difficult to achieve with a single material or single structure, thereby reducing fatigue for the insole user and protecting foot health.

[0051] In addition, through customized functions designed for each individual layer, it can disperse the impact and pressure applied to the feet, minimize discomfort during walking, and support the natural movement of the feet.

[0052] Although embodiments of the present invention have been described in detail, the scope of the present invention is not limited thereto, and various modifications and improvements by those skilled in the art using the basic concept of the present invention as defined in the following claims also fall within the scope of the present invention. Explanation of the symbols

[0053] 10: Upper layer 20: Middle layer 30: Lower layer

Claims

Claim 1 An eco-friendly shoe insole having a multilayer structure comprising: 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); 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); 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). Claim 2 An eco-friendly shoe insole having a multilayer structure, characterized in that, in the upper layer of claim 1, the upper layer comprises a wetting agent comprising at least one of glycerin and sodium lauryl sulfate (SLS), and a thickening agent comprising at least one of starch and gelatin. Claim 3 A method for manufacturing an eco-friendly shoe insole having a multilayer structure, comprising the steps of: 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 to produce an upper layer; placing a second coffee grounds paste 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 with a press without a foaming agent, and then placing the second coffee grounds paste again, adding a foaming agent, and then compression molding with a press to produce an intermediate layer; and 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 then compression molding with a press without a foaming agent to produce a lower layer.

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