Midsole material, preparation method thereof and shoe

Abstract

The invention belongs to the field of shoe manufacturing, and particularly relates to an insole material, a preparation method thereof and a shoe. The preparation method comprises the following steps: molding a polymer material into an insole shape by adopting a molding process to obtain a sub-blank; placing the sub-blank in a high-pressure container, injecting supercritical gas into the high-pressure container, and filling the sub-blank to obtain a sub-blank filling material; and after filling is completed, pressure reduction is conducted on the high-pressure container, the supercritical gas is gradually recovered to be in a gaseous state and escapes from the filling sub-blank material so that the sub-blank can be foamed, the filling sub-blank material forms a micropore structure in the gas escaping process, curing is completed, and the insole material is obtained. By means of the technology, the performance of the shoe insole can be remarkably improved, including but not limited to improvement of the buffering performance, improvement of the rebound resilience and prolonging of the service life, meanwhile, light weight of the insole is achieved, and the environment-friendly requirement is met to a certain degree.

Description

Technical Field

[0001] The invention belongs to the field of shoe manufacturing, and in particular relates to a midsole material and a preparation method thereof and a shoe. Background Art

[0002] In the field of footwear manufacturing, the midsole is a key component that affects the comfort, cushioning and overall performance of shoes. Traditional midsole materials mainly include rubber, EVA (ethylene-vinyl acetate copolymer), PU (polyurethane), etc. These materials can provide basic cushioning and support functions to a certain extent, but as consumers' requirements for shoe performance continue to increase, traditional midsole materials have gradually exposed some limitations.

[0003] For example, although the rubber midsole has good wear resistance, it is relatively heavy and has limited elastic recovery performance; the EVA midsole is relatively light and has a certain elasticity, but it is prone to compression deformation during long-term use, resulting in a decrease in cushioning performance; although the PU midsole has certain advantages in elasticity and wear resistance, it is more expensive and the processing technology is relatively complex.

[0004] At present, in terms of midsole manufacturing technology, it is common to form midsole materials through injection molding, compression molding, etc. These traditional processes have bottlenecks in the microstructure control and performance improvement of materials. For example, during the injection molding process, the pore structure inside the material is difficult to accurately control, resulting in uneven density distribution of the midsole, affecting the overall comfort and stability of the shoe. Moreover, traditional processes make it difficult for materials with different properties to achieve an ideal composite structure inside the midsole, limiting the further improvement of the comprehensive performance of the midsole.

[0005] More specific:

[0006] In the traditional EVA midsole injection molding technology, the EVA granular raw material is added to the barrel of the injection molding machine, and the EVA material is heated and plasticized to become a molten state. Then, under a certain pressure, the molten EVA is injected into the pre-designed midsole mold cavity, and after cooling and shaping, the EVA midsole product is demolded. The disadvantage of this traditional technology is that, as mentioned above, the pore structure of the EVA material is difficult to accurately control during the injection molding process, and it is easy to have a local density that is too large or too small. During long-term wear, areas with lower density are prone to excessive compression and deformation, while areas with higher density may cause local pressure concentration on the foot, affecting wearing comfort. In addition, due to the performance limitations of the EVA material itself, its cushioning performance and elastic recovery ability will gradually decay after multiple compressions, and cannot meet the needs of some high-performance sports or long-term wear scenarios.

[0007] In the traditional rubber midsole compression molding technology, the rubber raw materials are pre-treated by mixing and molding, and then placed in the midsole mold. A certain pressure is applied by a press to form and vulcanize the rubber in the mold. The vulcanization process causes the rubber molecular chains to undergo a cross-linking reaction, thereby giving the rubber midsole a certain strength, elasticity and wear resistance. The disadvantage of this technology is that the density of rubber is relatively high, which increases the overall weight of the shoe, which is not conducive to the wearer's athletic performance. Moreover, the elastic recovery performance of the rubber midsole is relatively poor. When subjected to a large impact force, it cannot quickly and effectively absorb energy and convert it into elastic potential energy for release, resulting in an unsatisfactory cushioning effect. In addition, the production process of the rubber midsole is relatively complex, the production cycle is long, and the cost is also high, which is not conducive to large-scale production and market promotion.

[0008] In summary, the existing shoe midsole manufacturing technology has certain limitations in terms of material properties and manufacturing process, and it is difficult to meet the comprehensive needs of modern consumers for shoe comfort, lightness, high performance, etc. Therefore, it is necessary to develop a new shoe midsole filling technology to overcome these problems. Based on this, the technical solution of the present invention is proposed. Summary of the invention

[0009] In order to solve the problems existing in the prior art, the present invention provides a method for preparing a midsole material, the preparation method comprising the following steps:

[0010] (1) using a molding process to mold the polymer material into a midsole shape to obtain a sub-embryo;

[0011] (2) placing the daughter embryo in a high-pressure container, and then injecting supercritical gas into the high-pressure container to fill the daughter embryo to obtain a filled daughter embryo material;

[0012] (3) After the filling is completed, the high-pressure container is depressurized to allow the supercritical gas to gradually return to a gaseous state and escape from the filling embryo material to foam the embryo. During the gas escape process, the filling embryo material forms a microporous structure and completes solidification, thereby obtaining the midsole material.

[0013] Preferably, in step (1), the molding process is an injection molding process or an extrusion molding process.

[0014] Preferably, in step (1), the polymer material is thermoplastic polyurethane elastomer rubber or polyether block amide.

[0015] Preferably, in step (2), the supercritical gas is supercritical nitrogen or supercritical carbon dioxide; wherein:

[0016] During the filling process, the circulation flow rate of the supercritical gas is 1 to 10 L / min, and the circulation time is 10 to 60 min.

[0017] Preferably, in step (2), a functional additive is added during the filling process; wherein:

[0018] The functional additives include one or a combination of two or more of nano silicon dioxide, nano calcium carbonate, anti-aging agents and antibacterial agents.

[0019] Preferably, the mass ratio of the functional additive to the daughter embryo is 0.1 to 10:100.

[0020] Preferably, in step (3), the rate of decompression is 0.1-1 MPa / min.

[0021] Preferably, in step (3), the diameter of the micropores is 0.1 to 1 mm, and the distribution density of the micropores is 10 to 100 per cm 2 .

[0022] Based on the same technical concept, another solution of the present invention is to provide a midsole material obtained by the above preparation method.

[0023] Based on the same technical concept, another solution of the present invention is to provide a shoe comprising the midsole material.

[0024] In order to facilitate understanding of the present invention, the process of the present invention is described in detail:

[0025] (I) First, you need to select a supercritical fluid, which can be supercritical nitrogen or supercritical carbon dioxide. Let's take supercritical carbon dioxide as an example: supercritical carbon dioxide (CO2) is used as the main supercritical fluid medium. Supercritical carbon dioxide has the advantages of being non-toxic, odorless, non-flammable, and having a relatively low critical temperature (31.1°C) and critical pressure (7.38MPa), which makes it easy to operate and control in industrial production. In use, the carbon dioxide gas will be pressurized to a pressure exceeding its critical pressure through a compressor, and heated to a temperature exceeding its critical temperature through a heat exchanger to make it reach a supercritical state.

[0026] (ii) Secondly, for the midsole material, high-performance polymer materials are selected as the base materials of the midsole, such as thermoplastic polyurethane elastomer rubber (TPU) or polyether block amide (PEBA). These materials have excellent mechanical properties, wear resistance and chemical resistance. In addition, the selected base material is made into the preliminary shape of the midsole through processes such as injection molding or extrusion molding.

[0027] (III) Again, in order to meet the filling requirements of supercritical dioxide, a corresponding filling device is required, which includes a high-pressure container, a pressure controller, a temperature controller, a fluid delivery system and a midsole fixing fixture. More specifically:

[0028] High-pressure container: It can withstand the high-pressure environment of supercritical carbon dioxide. Its internal volume is designed according to the production scale and the size of the bottom, generally between 0.1 and 1 cubic meter. The high-pressure container is cylindrical and made of high-strength alloy steel. Its inner wall is specially treated to prevent carbon dioxide corrosion. There is a sealing cover on the top of the container, which is tightened and sealed by bolts.

[0029] Pressure controller: The pressure in the high-pressure container is monitored in real time through the pressure sensor, and the pressure is accurately controlled within the required range of supercritical carbon dioxide through the regulating valve. The pressure control accuracy can reach ±0.1MPa. The pressure sensor is installed inside the high-pressure container to monitor the pressure in the container in real time and transmit the signal to the pressure controller. The pressure controller adjusts the pressure in the high-pressure container through the regulating valve according to the received signal.

[0030] Temperature controller: Using heating elements and cooling elements, the temperature in the container is stabilized at the appropriate temperature of supercritical carbon dioxide according to process requirements, with a temperature control accuracy of ±0.5°C. The temperature sensor is also installed in the high-pressure container to monitor the temperature and transmit the information to the temperature controller, which maintains the temperature stability in the high-pressure container through heating wires and cooling water pipes.

[0031] Fluid delivery system: including high-pressure pumps, pipelines and valves, etc., used to deliver supercritical carbon dioxide to high-pressure containers and ensure stable flow and accurate measurement of the fluid. As the core component of the fluid delivery system, the high-pressure pump pressurizes carbon dioxide gas to a supercritical state and then delivers it to the high-pressure container. The pipeline connects the high-pressure pump and the container, and the pipeline is equipped with a valve to control the on / off and flow rate of the fluid.

[0032] Midsole Fixing Fixture: It can firmly fix the midsole with microporous structure in the corresponding position in the high-pressure container, ensuring that the supercritical carbon dioxide can be evenly filled into the micropores or channels of the midsole. The midsole fixing fixture is located at the bottom of the high-pressure container and consists of an adjustable bracket and a clamping device. The bracket can be adjusted in height and angle according to the size of the midsole, and the clamping device can firmly clamp the midsole to ensure the stability of the midsole during the filling process.

[0033] During the filling process, the embryo will first be placed on the midsole fixing fixture and installed in a high-pressure container. Supercritical carbon dioxide is injected into the high-pressure container through a fluid delivery system, and the pressure and temperature in the container are kept within the set supercritical state parameter range through a pressure controller and a temperature controller. In the supercritical state, carbon dioxide has a diffusivity similar to that of gas and a solubility similar to that of liquid, and can penetrate into the interior of the embryo. In order to improve the filling effect, a cyclic filling method can be adopted, that is, supercritical carbon dioxide is allowed to circulate in the midsole for a certain period of time. The cycle time is generally between 10 and 60 minutes, and the cycle flow rate is between 1 and 10L / min. During the filling process, an appropriate amount of functional additives, such as nanoparticles (such as nano-silicon dioxide, nano-calcium carbonate, etc.) or functional polymers (such as anti-aging agents, antibacterial agents, etc.) can be added to the supercritical carbon dioxide as needed. These additives can be pre-dissolved or dispersed in supercritical carbon dioxide, and then filled into the midsole together with carbon dioxide, thereby giving the midsole more functional characteristics. The amount of additives added is generally between 0.1 and 10% of the mass of the embryo. In fact, the filling materials can be selected according to the performance characteristics required by the footwear. For example, if you want to improve the support and stability of the midsole, you can choose nanofibers or ceramic particles with high strength and rigidity; if you focus on improving cushioning performance and elasticity, you tend to use rubber microspheres with high elastic modulus or polymer particles with special structures. These filling materials can be evenly dispersed inside the midsole material under the action of supercritical fluid, forming a unique micro-composite structure.

[0034] It should be noted that before supercritical filling, the embryo material needs to undergo pretreatment steps such as cleaning and drying to remove surface impurities and moisture, ensure that the supercritical fluid can smoothly penetrate into the interior of the embryo material, and avoid impurities from having adverse effects on the filling process and final product performance.

[0035] (IV) Finally, after the supercritical filling is completed, the pressure in the high-pressure container is slowly reduced through the pressure controller, so that the supercritical carbon dioxide gradually returns to the gaseous state and escapes from the midsole. The pressure will be released during the decompression process, and then the gas will escape and complete the foaming and form micropores. The diameter of the micropores is generally between 0.1 and 1 mm, and the distribution density is between 10 and 100 per square centimeter. These micropores are interconnected to form a continuous channel network in which additives can be dispersed. In addition, as the carbon dioxide in the micropores in the midsole material is gradually discharged, the midsole material will shrink and solidify to a certain extent due to its own elasticity and viscosity, thereby fixing the additives filled therein and the residual carbon dioxide gas inside the midsole to form a unique microstructure. The decompression rate is generally controlled between 0.1 and 1 MPa / min. The midsole after decompression curing is subjected to necessary post-processing, such as surface polishing, laminating the upper, etc., to finally make a complete footwear product.

[0036] The beneficial effects of the present invention are:

[0037] The preparation method of the present invention utilizes the unique physical properties of supercritical carbon dioxide in a supercritical state. Its density is close to that of liquid, and it has strong solubility, and can dissolve or disperse various additives; at the same time, its viscosity is close to that of gas, and its diffusion coefficient is large, so it can quickly penetrate into the micropores of the midsole material. During the filling process, the supercritical carbon dioxide carries the additives to the inside of the midsole, and during the decompression process, as the carbon dioxide escapes, the midsole material shrinks and solidifies, and the additives are evenly fixed in the microstructure of the midsole, thereby changing the physical and chemical properties of the midsole. For example, nanoparticle additives can enhance the strength and wear resistance of the midsole, and functional polymer additives can give the midsole antibacterial, anti-aging and other properties. At the same time, since the supercritical carbon dioxide filling process does not require the use of a large amount of organic solvents or other chemicals, the pollution to the environment is reduced, and the micropores or channel structures inside the midsole not only reduce the weight, but also help to improve the cushioning performance and resilience of the midsole.

[0038] More specific:

[0039] 1. The supercritical process adopted by the present invention significantly reduces the material density of the midsole while ensuring sufficient structural strength and support. Under the condition of the same volume of the sole, the weight of the midsole using this technology can be reduced compared with the existing technology. This not only reduces the burden on the wearer's feet when walking or exercising, and improves the comfort of wearing, but also effectively reduces transportation costs and improves logistics efficiency when mass-producing footwear products, which meets the current market demand trend for lightweight footwear products.

[0040] 2. The present invention uses supercritical technology to precisely control the microporous structure and distribution of the belly-filling material, so that the midsole has more excellent elasticity and resilience. In repeated compression tests, the elastic deformation recovery rate of the midsole of the present invention is improved compared with the prior art. This means that during exercise, the sole can better absorb and release energy, provide the wearer with better cushioning and power-assisting effects, and effectively reduce the risk of sports injuries. It is particularly suitable for sports shoes, running shoes and other footwear products that have high requirements for sole performance, and significantly improves the sports performance and durability of the shoes.

[0041] 3. The supercritical midsole filling technology used in the present invention greatly reduces the use and emission of harmful chemicals during the production process. Compared with the traditional midsole manufacturing process, the emission of volatile organic compounds (VOC) is reduced, which reduces the pollution to the environment and the potential harm to the health of production workers. It complies with modern environmental protection concepts and relevant environmental protection laws and regulations, helps enterprises establish a good social image and avoid potential legal risks and economic losses caused by environmental problems.

[0042] 4. The supercritical process used in the present invention has unique rapid penetration and uniform filling characteristics, which can significantly shorten the processing time of midsole filling. Compared with the existing technology, the overall production cycle can be shortened, enabling enterprises to meet market order needs in a shorter time, improving production flexibility and market response speed, enhancing the competitiveness of enterprises in the fierce market competition, and also helping to reduce production costs and improve the economic benefits of enterprises. DETAILED DESCRIPTION

[0043] To make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described in detail below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other implementation methods obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present invention.

[0044] Example 1

[0045] This embodiment provides a method for preparing a midsole material, the method comprising the following steps:

[0046] (1) using an extrusion molding process to mold the thermoplastic polyurethane elastomer rubber into a midsole shape to obtain a sub-embryo;

[0047] (2) The sub-embroidery is first subjected to pretreatment steps such as cleaning and drying to remove surface impurities and moisture, thereby ensuring that the supercritical fluid can smoothly penetrate into the interior of the material and preventing impurities from having adverse effects on the filling process and final product performance; then the sub-embroidery is placed in a high-pressure container, and supercritical carbon dioxide is injected into the high-pressure container to fill the sub-embroidery to obtain a filled midsole;

[0048] The circulation flow rate of supercritical carbon dioxide in this process is 1L / min, and the circulation time is 60min. In addition, nano-silicon dioxide additive is added in this process, and the added mass is 0.1% of the mass of the embryo.

[0049] (3) After the filling is completed, the high-pressure container is decompressed at a rate of 0.1 MPa / min, so that the supercritical carbon dioxide gradually returns to a gaseous state and escapes from the bottom to foam the embryo. During the gas escape process, the filled embryo material forms a microporous structure (the diameter of the micropores is about 0.1 mm after final detection, and the distribution density of the micropores is about 50 / cm 2 ) and complete curing to obtain the midsole material.

[0050] Example 2

[0051] This embodiment provides a method for preparing a midsole material, the method comprising the following steps:

[0052] (1) using an extrusion molding process to mold the polyether block amide into a midsole shape to obtain a sub-embryo;

[0053] (2) The sub-embroidery is first subjected to pretreatment steps such as cleaning and drying to remove surface impurities and moisture, thereby ensuring that the supercritical fluid can smoothly penetrate into the interior of the material and preventing impurities from having adverse effects on the filling process and final product performance; then the sub-embroidery is placed in a high-pressure container, and supercritical carbon dioxide is injected into the high-pressure container to fill the sub-embroidery to obtain a filled midsole;

[0054] The circulation flow rate of supercritical carbon dioxide in the process is 10L / min, and the circulation time is 10min. In addition, nano-silicon dioxide additives are added in the process, and the added mass is 10% of the mass of the midsole with microporous structure.

[0055] (3) After the filling is completed, the high-pressure container is decompressed at a rate of 1 MPa / min, so that the supercritical carbon dioxide gradually returns to a gaseous state and escapes from the bottom to foam the embryo. During the gas escape process, the filled embryo material forms a microporous structure (the diameter of the micropores is about 1 mm after final detection, and the distribution density of the micropores is about 10 / cm 2 ) and complete curing to obtain the midsole material.

[0056] Example 3

[0057] This embodiment provides a method for preparing a midsole material, the method comprising the following steps:

[0058] (1) using an extrusion molding process to mold the thermoplastic polyurethane elastomer rubber into a midsole shape to obtain a sub-embryo;

[0059] (2) The sub-embroidery is first subjected to pretreatment steps such as cleaning and drying to remove surface impurities and moisture, thereby ensuring that the supercritical fluid can smoothly penetrate into the interior of the material and preventing impurities from having adverse effects on the filling process and final product performance; then the sub-embroidery is placed in a high-pressure container, and supercritical carbon dioxide is injected into the high-pressure container to fill the sub-embroidery to obtain a filled midsole;

[0060] The circulation flow rate of supercritical carbon dioxide in this process is 5L / min, and the circulation time is 30min. In addition, nano-silicon dioxide additive is added in this process, and the added mass is 5% of the embryo mass.

[0061] (3) After the filling is completed, the high-pressure container is decompressed at a rate of 0.5 MPa / min, so that the supercritical carbon dioxide gradually returns to a gaseous state and escapes from the bottom to foam the embryo. During the gas escape process, the filled embryo material forms a microporous structure (the diameter of the micropores is about 0.5 mm after final detection, and the distribution density of the micropores is about 20 / cm 2 ) and complete curing, and then the filled midsole completes curing to obtain the midsole material.

[0062] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for preparing a midsole material, characterized in that: The preparation method comprises the following steps: (1) using a molding process to mold the polymer material into a midsole shape to obtain a sub-embryo; (2) placing the daughter embryo in a high-pressure container, and then injecting supercritical gas into the high-pressure container to fill the daughter embryo to obtain a filled daughter embryo material; (3) After the filling is completed, the high-pressure container is depressurized to allow the supercritical gas to gradually return to a gaseous state and escape from the filling embryo material to foam the embryo. During the gas escape process, the filling embryo material forms a microporous structure and completes solidification, thereby obtaining the midsole material.

2. The method for preparing the midsole material according to claim 1, characterized in that: In step (1), the molding process is an injection molding process or an extrusion molding process.

3. The method for preparing the midsole material according to claim 1, characterized in that: In step (1), the polymer material is thermoplastic polyurethane elastomer rubber or polyether block amide.

4. The method for preparing the midsole material according to claim 1, characterized in that: In step (2), the supercritical gas is supercritical nitrogen or supercritical carbon dioxide; wherein: During the filling process, the circulation flow rate of the supercritical gas is 1 to 10 L / min, and the circulation time is 10 to 60 min.

5. The method for preparing the midsole material according to claim 1, characterized in that: In step (2), a functional additive is added during the filling process; wherein: The functional additives include one or a combination of two or more of nano silicon dioxide, nano calcium carbonate, anti-aging agents and antibacterial agents.

6. The method for preparing the midsole material according to claim 5, characterized in that: The mass ratio of the functional additive to the daughter embryo is 0.1 to 10:

100.

7. The method for preparing the midsole material according to claim 1, characterized in that: In step (3), the rate of decompression is 0.1-1 MPa / min.

8. The method for preparing the midsole material according to claim 1, characterized in that: In step (3), the diameter of the micropores is 0.1 to 1 mm, and the distribution density of the micropores is 10 to 100 per cm 2 .

9. The midsole material obtained by the preparation method according to any one of claims 1 to 8.

10. A shoe, characterized in that: The midsole material according to claim 9 is included.