A double-layer foamed shoe sole and a method for manufacturing the same

Abstract

The present application relates to the technical field of foaming shoe sole, especially to a double-layer foaming shoe sole, comprising a first shoe sole and a second shoe sole, the first shoe sole is prepared from the following raw materials in percentage: 50%-60% EVA particles, 7%-9% talcum powder, 0.25%-0.27% stearic acid, 0.34%-0.38% DCP, 0.98%-1.2% AC, and 0.96%-1% zinc oxide; the second shoe sole is prepared from the following raw materials in percentage: 22%-27% EVA particles, 4%-6% POE, 1.8%-2.3% talcum powder, 0.14%-0.16% stearic acid, 0.18%-0.22% DCP, 1%-1.2% AC, and 0.4%-0.6% zinc oxide, which can produce an integrally injection-molded double-layer shoe sole, the first shoe sole and the second shoe sole are respectively adjusted for the ground and the sole, which not only ensures the wear resistance of the shoe sole, but also ensures the comfort of people wearing, and the structure is foamed twice in succession, the heat of the second foaming is used to make the EVA sheet hot melt, avoiding the use of glue and other adhesion, which is more firm, and the finished shoe sole is not easy to separate.

Description

Technical Field

[0001] This invention relates to the technical field of foamed shoe soles, and more particularly to a double-layer foamed shoe sole and its manufacturing method. Background Technology

[0002] The general method for manufacturing foam soles involves manually placing the foaming material into a molding mold or injecting it into a mold using an injection molding machine. The mold is then heated to a curing temperature before being opened. During the mold opening process, the foaming material inside the mold will foam, thus forming a lightweight and soft sole. However, these are all single-layer soles. If they are too soft, it will affect the wear resistance; if they are too hard, it will affect the wearing comfort, which cannot meet people's needs. Nowadays, some soles are spliced ​​together by gluing to form double-layer soles, but this is not very strong, and the soles are easy to separate. Summary of the Invention

[0003] The present invention provides a double-layer foamed shoe sole and its manufacturing method, so as to achieve the purpose of producing an integrated double-layer foamed shoe sole that ensures both wear resistance and comfort.

[0004] To achieve the above objectives, the present invention provides the following technical solution: a double-layer foamed shoe sole, comprising a first sole and a second sole.

[0005] The first sole is made from the following raw materials in percentage: 50%-60% EVA particles, 7%-9% talc, 0.25%-0.27% stearic acid, 0.34%-0.38% DCP, 0.98%-1.2% AC, and 0.96%-1% zinc oxide;

[0006] The second sole is made from the following raw materials in percentages: 22%-27% EVA particles, 4%-6% POE, 1.8%-2.3% talc, 0.14%-0.16% stearic acid, 0.18%-0.22% DCP, 1%-1.2% AC, and 0.4%-0.6% zinc oxide.

[0007] Furthermore, the EVA particles include 7350 EVA particles and 7470 EVA particles.

[0008] Furthermore, the EVA particles used in preparing the first sole include 26%-33% 7350EVA particles and 24%-27% 7470EVA particles, and the EVA particles used in preparing the second sole include 12%-15% 7350EVA particles and 10%-12% 7470EVA particles.

[0009] Furthermore, the raw materials of the first and second soles also include 5%-10% color masterbatch.

[0010] Furthermore, the raw material of the second sole also includes 0.9%-1.2% crosslinking agent.

[0011] A preparation method includes the following steps:

[0012] S1, mix the raw materials needed for the first and second soles according to the specified weight ratio;

[0013] S2, the raw material for the second sole is poured into a cold molding machine for injection to produce an EVA sheet;

[0014] S3, after fixing the EVA sheet, pour the raw material of the first shoe sole onto it, put it into a small foaming mold foaming machine for foaming, and obtain a semi-finished dual-density integrated EVA sheet;

[0015] S4, roughen the outer skin of the integrated EVA sheet;

[0016] S5 involves placing an integrated EVA sheet into a molding machine for heating, followed by cooling to obtain the final product.

[0017] Furthermore, in step S3, foaming needs to last for more than 650 seconds.

[0018] Furthermore, in step S5, the heating time is 500-550 seconds, and the heating temperature must reach above 300°C.

[0019] Furthermore, the cooling time in step S5 is greater than 500 seconds.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows: with the raw materials in this formulation and the preparation method, a double-layer shoe sole can be produced by one-piece injection molding. The first and second shoe soles are designed to be adjusted for the ground and the sole of the foot, respectively, which ensures both the wear resistance of the shoe sole and the comfort of people wearing it. At the same time, the structure is formed by two foaming processes, and the heat of the second foaming process is used to heat-melt and bond the EVA sheet together, avoiding the use of glue or other bonding agents, making it more secure and the finished shoe sole is not easy to separate. Detailed Implementation

[0021] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] This invention discloses a double-layer foamed shoe sole, comprising a first sole and a second sole.

[0023] The first sole is made from the following raw materials in percentage: 50%-60% EVA particles, 7%-9% talc, 0.25%-0.27% stearic acid, 0.34%-0.38% DCP, 0.98%-1.2% AC, and 0.96%-1% zinc oxide;

[0024] The second sole is made from the following raw materials in percentages: 22%-27% EVA particles, 4%-6% POE, 1.8%-2.3% talc, 0.14%-0.16% stearic acid, 0.18%-0.22% DCP, 1%-1.2% AC, and 0.4%-0.6% zinc oxide. The main function of talc is for demolding. Stearic acid and zinc oxide are used to control the foaming rate. The percentages are adjusted within this range. Too little will easily result in incomplete foaming. The amount of stearic acid and zinc oxide in the first and second soles depends on the increase or decrease of the proportion of EVA particles. The first and second soles are made of the same material, both being EVA. This technical solution can produce two soles with different hardnesses under the same material and produce a strong and reliable sole in one piece.

[0025] In this embodiment, the EVA particles include 7350 EVA particles and 7470 EVA particles.

[0026] In this embodiment, the EVA particles used to prepare the first shoe sole include 26%-33% 7350EVA particles and 24%-27% 7470EVA particles, and the EVA particles used to prepare the second shoe sole include 12%-15% 7350EVA particles and 10%-12% 7470EVA particles.

[0027] In this embodiment, the raw materials of the first and second soles also include 5%-10% color masterbatch, which is mainly used for coloring. The raw materials of the second sole also include 0.9%-1.2% crosslinking agent, which is mainly used to make the first and second soles fit together better.

[0028] A preparation method includes the following steps:

[0029] S1, mix the raw materials needed for the first and second soles according to the specified weight ratio;

[0030] S2, the raw material for the second sole is poured into a cold molding machine for injection to produce an EVA sheet;

[0031] S3, after fixing the EVA sheet, pour the raw material of the first shoe sole onto it, put it into a small foaming mold foaming machine for foaming, and obtain a semi-finished dual-density integrated EVA sheet;

[0032] S4, roughen the outer skin of the integrated EVA sheet;

[0033] S5 involves placing an integrated EVA sheet into a molding machine for heating, followed by cooling to obtain the final product.

[0034] In this embodiment, foaming for more than 650 seconds is required in step S3, heating for 500-550 seconds and reaching a temperature of 300°C or higher is required in step S5, and cooling for more than 500 seconds is required in step S5. This temperature allows the first and second soles to fit together more firmly. The heating and cooling times ensure the molding process. If the cooling time is insufficient, the soles may deform or have other defects. The heating time is mainly related to the environment or weather. When the ambient temperature is low, the heating time can be appropriately extended. Granulation should be performed before step S1. Raw materials such as EVA particles are cut and granulated using a granulator. The granulator processing time is about 15 minutes per 3KG of raw material.

[0035] The manufacturing sequence is to first form the second sole (soft padding layer) and then the first sole (hard bottom layer). Using this ratio of raw materials and the preparation method, a one-piece injection-molded double-layer sole can be produced. The design of the first and second soles is adjusted for the ground and the sole of the foot, respectively, which ensures both the wear resistance of the sole and the comfort of the wearer. At the same time, this structure involves two foaming processes, using the heat from the second foaming to heat-melt and bond the EVA sheets together, avoiding the use of glue or other bonding agents, making it more secure and less prone to separation after the sole is finished.

[0036] Example 1: The first sole is composed of 50% EVA particles, 7% talc, 0.25% stearic acid, 0.34% DCP, 0.98% AC, and 0.96% zinc oxide. The 50% EVA particles include 26% 7350 EVA particles and 24% 7470 EVA particles. The second sole is composed of 22% EVA particles, 4% POE, 1.8% talc, 0.14% stearic acid, 0.18% DCP, 1% AC, and 0.4% zinc oxide. The 22% EVA particles include 12% 7350 EVA particles and 10% 7470 EVA particles. The second sole also includes a color masterbatch for coloring. This mixture, following the preparation method, produces an integrated double-layer sole. However, it may have defects such as insufficient sole hardness, difficulty in demolding during production, poor adhesion, and lack of firmness.

[0037] Example 2: A first sole was composed of 60% EVA particles (33% 7350 EVA particles and 27% 7470 EVA particles), 9% talc, 0.27% stearic acid, 0.38% DCP, 1.2% AC, and 1% zinc oxide. A second sole was composed of 27% EVA particles (15% 7350 EVA particles and 12% 7470 EVA particles), 6% POE, 2.3% talc, 0.16% stearic acid, 0.22% DCP, 1.2% AC, and 0.6% zinc oxide. This resulted in an integrated double-layer sole with excessive hardness, which affected comfort.

[0038] Example 3: A one-piece double-layer shoe sole is made by using raw materials consisting of 55% EVA particles (29% 7350 EVA particles and 26% 7470 EVA particles), 8% talc, 0.26% stearic acid, 0.36% DCP, 1% AC, and 0.98% zinc oxide as the first sole and 25% EVA particles (15% 7350 EVA particles and 10% 7470 EVA particles), 5% POE, 2% talc, 0.15% stearic acid, 0.2% DCP, 1.1% AC, and 0.5% zinc oxide as the second sole. The second sole has a hardness of 20-25, and the first sole has a hardness of 30-35. This design is both wear-resistant and comfortable. Production is normal with no demolding difficulties. Occasionally, there may be some flash, which can be removed. A crosslinking agent can be added to make the bonding stronger.

[0039] In Example 4, color masterbatch can be added to either the first or second sole when the EVA sheet is made, or color masterbatch can be added to both soles at the same time, thereby forming a two-color combination of the first and second soles, or a unified color scheme, to improve aesthetics.

[0040] The above embodiments are preferred embodiments of the present invention. Any structures similar to those of the present invention and any equivalent changes thereof should fall within the protection scope of the present invention.

Claims

1. A double-layer foamed shoe sole, comprising a first sole and a second sole, characterized in that: The first sole is made from the following raw materials in percentages: 50%-60% EVA particles, 7%-9% talc, 0.25%-0.27% stearic acid, 0.34%-0.38% DCP, 0.98%-1.2% AC, and 0.96%-1% zinc oxide; the second sole is made from the following raw materials in percentages: 22%-27% EVA particles, 4%-6% POE, 1.8%-2.3% talc, 0.14%-0.16% stearic acid, 0.18%-0.22% DCP, 1%-1.2% AC, 0.4%-0.6% zinc oxide, and 0.9%-1.2% crosslinking agent; The EVA particles include 7350 EVA particles and 7470 EVA particles; The EVA particles used in the preparation of the first shoe sole include 26%-33% 7350EVA particles and 24%-27% 7470EVA particles, while the EVA particles used in the preparation of the second shoe sole include 12%-15% 7350EVA particles and 10%-12% 7470EVA particles.

2. The double-layer foamed shoe sole according to claim 1, characterized in that: The raw materials of the first and second soles also include 5%-10% color masterbatch.

3. The method for preparing a double-layer foamed shoe sole according to claim 1, characterized in that: The steps include the following: S1, mix the raw materials needed for the first and second soles according to the specified weight ratio; S2, the raw material for the second sole is poured into a cold molding machine for injection to produce an EVA sheet; S3, after fixing the EVA sheet, pour the raw material of the first shoe sole onto it, put it into a small foaming mold foaming machine for foaming, and obtain a semi-finished dual-density integrated EVA sheet; S4, roughen the outer skin of the integrated EVA sheet; S5 involves placing an integrated EVA sheet into a molding machine for heating, followed by cooling to obtain the final product.

4. The method for preparing a double-layer foamed shoe sole according to claim 3, characterized in that: In step S3, foaming needs to last for more than 650 seconds.

5. The method for preparing a double-layer foamed shoe sole according to claim 3, characterized in that: In step S5, the heating time is 500-550 seconds, and the heating temperature must reach above 300°C.

6. The method for preparing a double-layer foamed shoe sole according to claim 3, characterized in that: The cooling time in step S5 is greater than 500 seconds.