Bifunctional high-elasticity shock-absorbing Hybrid insole and preparation method thereof

Abstract

The invention discloses a bifunctional hybrid insole with high elasticity and shock absorption and a preparation method of the hybrid insole, and relates to the field of insole manufacturing. According to the dual-function high-elasticity and shock-absorbing Hybrid insole and the preparation method thereof, the half sole area is made of a POE high-elasticity material, and through twin-screw extrusion molding and plasma surface treatment, high elasticity with the rebound rate being larger than or equal to 60% and the Shore hardness C being 55-65 is achieved; the heel area is made of a low-density microcellular foaming EVA shock absorption material, and a uniform structure with the pore diameter of 100-200 microns is obtained by accurately controlling foaming parameters. Through material innovation, structure optimization and process precise control, the leap-type upgrade of the insole function from single buffering to biomechanical adaptation is realized; the technical key point is that the performance coordination of the partitioned composite material, the process breakthrough of the interface strength and the dynamic mechanical transition design, and the actual effect is that the movement efficiency is improved, the joint protection is enhanced, and the service life of the product is prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of insole manufacturing, and specifically to a Hybrid insole with both dual functions of high elasticity and shock absorption and a preparation method thereof. Background Art

[0002] In recent years, with the development of sports science, the functional design of insoles has gradually evolved from single buffering to biomechanical adaptation; some domestic patents have attempted to improve the performance of insoles through regional material design. Among the existing technologies, some patented partitioned insoles use high-density EVA shock-absorbing materials in the forefoot and silicone cushions in the heel; however, this design still has significant deficiencies: First, the bonding of material interfaces relies on traditional hot pressing processes, and the interface peel strength only reaches 4-5 MPa, making delamination prone to occur during long-term use; second, the mechanical property transition between the forefoot and the heel is rigid, lacking a gradient design, resulting in low energy transfer efficiency during exercise; some other patents use gradient foaming technology to optimize the density distribution of insoles, but their material selection is limited to a single EVA shock-absorbing material system, and the forefoot rebound rate is only 45%-50%, which cannot meet the requirements of high-intensity exercise for ground pushing assistance; in addition, existing processes generally face problems such as low precision in controlling the foaming pore size (the pore size deviation of the micro-porous insoles disclosed in some patents reaches ±50 μm) and insufficient integration of antibacterial and support functions, which limit the comprehensive performance of insoles and the expansion of application scenarios.

[0003] In terms of biomechanical adaptability, the homogeneous structure of traditional insoles is difficult to match the different force requirements of the forefoot and the heel of the foot; the forefoot area requires high-elasticity materials (rebound rate ≥ 65%) to improve the ground pushing efficiency, while the heel area requires high-shock-absorbing materials (compression deformation ≥ 50%) to reduce joint impact; however, among some partitioned insoles in the existing technology, although they attempt to combine POE high-elasticity materials with EVA shock-absorbing materials, they have not solved the problem of insufficient interface bonding strength between the two, and lack a transition zone design, resulting in uneven foot pressure distribution during exercise; in addition, most patents do not consider the optimization of the arch support structure, which is likely to cause foot fatigue during long-term use; at the process level, traditional molding technologies are difficult to achieve precise regional control of material properties. In some patent applications for insole preparation methods, the fluctuation range of foaming temperature and pressure exceeds ±10%, resulting in poor product consistency.

[0004] In summary, the existing insole technologies have significant defects in material adaptability, interface bonding strength, process precision, and biomechanical optimization. There is an urgent need for an innovative solution that combines the dual functions of high elasticity and shock absorption and can achieve stable mass production. Summary of the Invention

[0005] (I) Technical Problems to be Solved

[0006] Through the collaborative innovation of materials and processes, the present invention realizes the dual functions of high-elasticity assistance in the forefoot and shock absorption in the heel, significantly improves the sports efficiency and joint protection, fills the gap of the single function of traditional insoles, and is applicable to the multi-scenario needs such as running, basketball, and fitness.

[0007] (2) Technical Solution

[0008] To achieve the above object, the present invention provides the following technical solution: A Hybrid insole with both high elasticity and shock absorption functions, comprising the following structures:

[0009] a. Forefoot area, composed of POE high-elastic material, the rebound rate of the forefoot material ≥ 60%, and the hardness is Shore C55 - 65;

[0010] b. Heel area, composed of low-density microcellular foamed ethylene-vinyl acetate copolymer (EVA shock-absorbing material), the compression deformation of the heel material ≥ 55%, and the energy absorption rate ≥ 85%;

[0011] c. Gradient transition area, located between the forefoot area and the heel area, with a width of 10 - 15 mm, and the material hardness gradually decreases from Shore C60 to C40;

[0012] d. Bonding layer, containing nano-level polyurethane adhesive, and the interfacial bonding strength ≥ 8 MPa;

[0013] e. Arch support structure, embedded in the middle of the insole, and composed of a POE high-elastic material support sheet.

[0014] Preferably, the POE high-elastic material of the forefoot material is prepared by a twin-screw extruder, and the extrusion temperature is controlled in sections as follows: the feeding section is 160 °C, the compression section is 180 °C, the homogenization section is 190 °C, and the die head is 185 °C. The sheet thickness is 2.5 ± 0.2 mm; the surface of the forefoot material is treated by plasma, and the surface energy ≥ 60 mN / m, and laser micropores of 10 - 20 μm are formed.

[0015] Preferably, the microcellular EVA shock-absorbing material of the heel material is prepared by a compression molding and foaming process, the foaming pressure is 8 MPa, the temperature is 160 °C, the foaming ratio is 3.5 times, and the pore size distribution is 100 - 200 μm; the EVA shock-absorbing material premix contains blowing agent AC-3000 (3 wt%) and cross-linking agent DCP (0.8 wt%).

[0016] Preferably, the gradient transition area is formed by locally softening the junction of the POE high-elastic material and the EVA shock-absorbing material with a hot air gun, and the temperature is controlled at 120 °C to form a mechanical gradient interface with interpenetrating molecular chains.

[0017] Preferably, the coating amount of the nano-level polyurethane adhesive in the bonding layer is 20 g / m2, and it is activated by a hot pressing process at 160 ± 5 °C and a pressure of 6 MPa, with a holding pressure time of 40 seconds.

[0018] Preferably, the thickness of the POE high-elastic material support sheet of the arch support structure is 1.2 - 1.8 mm, and the surface is polished by a sand belt to a roughness ≤ Ra 3.2 μm.

[0019] A preparation method of a Hybrid insole, comprising the following steps:

[0020] S1. Preparation of the forefoot material: Extrude and mold the POE high-elastic material through a twin-screw extruder, and perform plasma treatment and laser micro-hole etching.

[0021] S2. Preparation of the heel material: Mix the EVA shock-absorbing material with a foaming agent and a cross-linking agent, then mold and foam, and cure for 24 hours.

[0022] S3. Composite lamination: After coating the forefoot and heel materials with a nano adhesive, hot press and laminate them at 160 ± 5 °C and 6 MPa, and remove air bubbles through vacuum adsorption.

[0023] S4. Mold pressing and forming: Place the composite sheet in a mold, and perform hydraulic forming at 120 °C and 12 MPa, and demold after cooling to 50 °C.

[0024] S5. Post-treatment: Laser cut and trim the edges, chamfer the edges, and perform tests on the resilience rate, compression deformation, and interfacial peel strength.

[0025] Preferably, in S3, the hot press lamination uses a multi-layer hot press, the vacuum degree is controlled at -0.08 MPa, and the temperature of the lamination interface ≥ 150 °C; in step (d), the mold design includes exhaust grooves (depth 0.2 mm, spacing 5 mm) and cooling water channels (diameter 6 mm, spacing 15 mm).

[0026] Preferably, the tests in S5 include:

[0027] 1) Resilience rate test: According to the ASTM D2632 standard, the falling ball height is 500 mm;

[0028] 2) Compression deformation test: According to the ISO 3386 standard, the pressure is 500 N and maintained for 24 hours;

[0029] 3) Interfacial peel test: According to the ASTM D903 standard, the peel rate is 100 mm / min.

[0030] Preferably, the preparation method further includes an antibacterial mesh fabric composite step: thermally press the silver ion antibacterial mesh fabric (grammage 150 g / m2) and the composite sheet at 130 °C and 3 MPa for 20 seconds for the second time, and the thickness of the hot melt adhesive pre-coated on the surface of the mesh fabric is 0.1 mm.

[0031] (III) Beneficial effects

[0032] Compared with the prior art, the present invention provides a Hybrid insole with both dual functions of high elasticity and shock absorption and its preparation method, having the following beneficial effects:

[0033] Through the design of partitioned composite materials and process innovation, the present invention realizes the comprehensive improvement of the functions and performance of the insole; firstly, the forefoot adopts a POE high-elastic material with a rebound rate as high as 72%-75%, which is significantly better than that of traditional EVA shock-absorbing material insoles (45%-50%), providing efficient energy feedback for the pushing-off action; the heel area selects a low-density microcellular EVA shock-absorbing material with a compression deformation of 54%-58% and an energy absorption rate exceeding 85%, effectively reducing the knee joint impact force by 22%-25%; secondly, the gradient transition zone design (width 10-15 mm) makes the hardness of the forefoot and the heel smoothly transition from Shore C 60 to C 40, avoiding the mechanical mutation problem of traditional partitioned insoles and optimizing the plantar pressure distribution; combined with nano-level polyurethane adhesives and plasma surface treatment technology, the interfacial peel strength is increased to 8.5-9.0 MPa, almost doubling compared with the prior art (4-5 MPa), completely solving the delamination risk.

[0034] At the process level, the innovation of the present invention is reflected in the precise control of the whole process; for example, in the molding and foaming process, by regulating the pressure (8 MPa), temperature (160 °C) and the proportion of the foaming agent (the proportion of AC-3000 is 3%), the pore size deviation of the microcellular EVA shock-absorbing material is controlled within ±20 μm, ensuring the stability of the shock-absorbing performance; the thermocompression composite process introduces a vacuum adsorption device (vacuum degree -0.08 MPa) and a PID temperature control system (fluctuation ≤ ±2 °C), making the bonding interface dense and bubble-free; in addition, the arch support structure adopts a POE high-elastic material sheet (thickness 1.2-1.8 mm) and a sand belt polishing technology (roughness ≤ Ra 3.2 μm), enhancing the arch stability. Fatigue tests show that there is no cracking after 100,000 cycles, and the service life is extended by 50% compared with traditional insoles.

[0035] From the perspective of application value, the present invention is not only suitable for high-intensity sports such as running and basketball, but can also be expanded to the field of medical rehabilitation; biomechanical tests show that its ground pushing efficiency is improved by 18%-20%, and the reduction in knee joint impact force is far greater than that of the control group (10%-15%); in terms of industrialization, the automated production line integrates a robotic arm and an AI visual inspection system, with a mass production yield of 99.5%, and the material cost only increases by 15%, but the overall performance is significantly improved, and it has strong market competitiveness; in terms of environmental protection, the recyclability of POE high-elastic materials and EVA shock-absorbing materials and the use of water-soluble adhesives reduce VOC emissions in the production process by 90%, which is in line with the trend of green manufacturing. DETAILED DESCRIPTION

[0036] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] Embodiment 1:

[0038] Materials and process parameters

[0039] Forefoot material: POE high elastic material, extrusion temperature: feeding section 160℃, compression section 180℃, homogenization section 190℃, die head 185℃, sheet thickness 2.5mm;

[0040] Heel material: microporous EVA shock-absorbing material (density 0.2g / cm3), foaming pressure 8MPa, temperature 160℃, foaming ratio 3.5 times;

[0041] Gradient transition zone: width 12mm, hot air gun treatment temperature 120℃;

[0042] Bonding layer: Nano polyurethane adhesive coating amount 20g / m2, hot pressing parameters 160℃, 6MPa, 40s;

[0043] Arch support sheet: POE high elastic material thickness 1.5mm, surface roughness Ra 3.0μm.

[0044] Preparation steps:

[0045] POE high elastic material is plasma treated after extrusion molding (surface energy 62mN / m), and laser etched with micropores (pore diameter 15μm);

[0046] The EVA shock-absorbing material is foamed and matured for 24 hours;

[0047] After hot pressing and laminating, it is laminated with the antibacterial mesh for the second time;

[0048] Compression molding (pressure 12 MPa, mold temperature 120 °C);

[0049] Laser cutting for trimming and inspection.

[0050] Example 2:

[0051] Adjust parameters:

[0052] Forefoot material: POE high-elastic material, other parameters are the same as in Example 1;

[0053] Heel material: The density of the microcellular EVA shock-absorbing material is adjusted to 0.18 g / cm3, and the foaming ratio is 4.0 times;

[0054] Gradient transition zone: Width 15 mm.

[0055] Preparation steps:

[0056] Same as Example 1, only adjust the material ratio and foaming parameters.

[0057] Example 3:

[0058] Adjust parameters:

[0059] Arch support sheet: POE high-elastic material with a thickness of 1.8 mm and a surface roughness Ra of 2.5 μm;

[0060] Gradient transition zone: Width 10 mm;

[0061] Bonding layer: Coating amount increased to 25 g / m2, hot pressing pressure 7 MPa.

[0062] Preparation steps:

[0063] Same as Example 1, only optimize the arch structure and bonding process.

[0064] Inspection:

[0065] 1. Rebound rate test (test standard method: ASTM D2632)

[0066] Steps: Fix the forefoot area of the insole, and a steel ball (diameter 20 mm, mass 50 g) freely falls from a height of 500 mm. Record the rebound height and calculate the rebound rate (rebound height / initial height × 100%).

[0067] Number of repetitions: Take the average value for 5 times.

[0068] 2. Compression deformation test (test standard: ISO 3386)

[0069] Steps: Apply a pressure of 500 N to the heel area and keep it for 24 hours. Measure the deformation amount (initial thickness - deformed thickness) / initial thickness × 100%.

[0070] 3. Interface Peel Strength Test (Test Standard Method: ASTM D903)

[0071] Steps: Use a universal material testing machine to peel the forefoot and heel bonding layer at a rate of 100 mm / min, and record the maximum peel force (unit: MPa).

[0072] 4. Fatigue Test

[0073] Steps: Simulate 100,000 walking cycles (frequency 2 Hz, load 800 N), and observe whether the insole cracks or delaminates.

[0074] 5. Biomechanics Test

[0075] Equipment: Plantar pressure distribution test system (Model: RSscan International).

[0076] Indicators: Vertical impact force of the knee joint (N), push-off efficiency (energy recovery rate %)

[0077] Comparison Detection Design:

[0078] Control Group 1: Traditional full-EVA shock-absorbing material insole (density 0.25 g / cm3, no zoning design).

[0079] Control Group 2: Existing zoned insole (forefoot EVA shock-absorbing material hardness Shore C 50, heel silicone compression deformation 40%, no gradient transition zone).

[0080] Comparison Table of Test Results:

[0081]

[0082]

[0083] The core technical solution of this patent lies in designing a dual-functional Hybrid insole with high-elastic support in the forefoot and shock absorption protection in the heel through material zoning composite and process innovation. The forefoot area uses POE high-elastic material, and through twin-screw extrusion molding and plasma surface treatment, a high-elastic performance with a rebound rate ≥ 60% and a Shore C hardness of 55 - 65 is achieved. The heel area selects low-density microcellular foamed EVA shock-absorbing material, and by precisely controlling the foaming parameters (pressure 8 MPa, temperature 160 °C, foaming ratio 3.5 times), a uniform structure with a pore size of 100 - 200 μm is obtained, with a compression deformation ≥ 55% and an energy absorption rate exceeding 85%. A 10 - 15 mm gradient transition zone is designed between the forefoot and the heel. Through local softening with a hot air gun and coating with nano-level polyurethane adhesive (coating amount 20 g / m²), a gradient interface with interpenetrating molecular chains is formed, and the interface peel strength reaches above 8.5 MPa, significantly superior to traditional processes. In addition, a POE high-elastic material arch support piece (thickness 1.2 - 1.8 mm) is embedded in the middle of the insole and polished with a sanding belt to a roughness ≤ Ra3.2 μm to further improve the arch stability. The preparation process covers the entire process of material pretreatment, hot pressing composite, molding, and post-treatment testing. Key parameters such as hot pressing temperature (160 ± 5 °C), pressure (6 MPa), and vacuum adsorption (-0.08 MPa) ensure product consistency.

[0084] Through the above technical solutions, this patent significantly improves the comprehensive performance and practical application value of the insole. In terms of function, the high-elastic material in the forefoot (rebound rate 72% - 75%) provides efficient assistance for the pushing-off action, which is nearly 60% higher than that of traditional EVA shock-absorbing material insoles (rebound rate 45%). The compression deformation of the microcellular EVA shock-absorbing material in the heel reaches 54% - 58%, the energy absorption rate exceeds 85%, and the vertical impact force on the knee joint is reduced by 20% - 25%, which is better than that of existing silicone insoles (reduction of 15%). The gradient transition zone design eliminates the sudden change in mechanical properties and optimizes the plantar pressure distribution. Combining nano-adhesive and plasma treatment technologies, the interface peel strength (8.5 - 9.0 MPa) is nearly doubled compared with existing zoned insoles (4 - 5 MPa), reducing the risk of delamination. In terms of process, the deviation of the molded foam pore size is controlled within ±20 μm. Vacuum adsorption and PID temperature control are introduced in the hot pressing composite, and the mass production yield is as high as 99.5%, and the service life is extended by 50%. Biomechanical tests show that its pushing-off efficiency is increased by 18% - 20%, and there is no failure after 100,000 cycles of fatigue testing, far exceeding the control group (cracking after 50,000 cycles). The application scenarios cover sports, medical rehabilitation, and elderly fall prevention fields, and the materials are recyclable and the process is environmentally friendly (VOC emissions are reduced by 90%), combining technological advancement and industrial feasibility.

[0085] Generally speaking, through material innovation, structural optimization and precise process control, this patent has achieved a leapfrog upgrade of the insole function from single buffering to biomechanical adaptation; the key technical points lie in the performance coordination of the partitioned composite materials, the process breakthrough of the interfacial strength, and the dynamic mechanical transition design, and the actual effects are reflected in the improvement of the sports efficiency, the enhancement of joint protection and the extension of the product life; the test data have comprehensively verified its significant advantages compared with the traditional solutions, providing an innovative solution for the fields of sports equipment and medical aids.

Claims

1. A hybrid insole with dual functions of high elasticity and shock absorption, characterized in that: include: a. The forefoot area is made of POE high-elastic material, the rebound rate of the forefoot material is ≥ 60%, and the hardness is Shore C 55-65; b. The heel area is composed of low-density microporous foamed ethylene-vinyl acetate copolymer (EVA shock-absorbing material), and the compression deformation of the heel material is ≥55%, and the energy absorption rate is ≥85%; c. Gradient transition zone, located between the forefoot area and the heel area, with a width of 10-15mm, and the material hardness gradually decreases from Shore C 60 to C 40; d. A bonding layer comprising a nano-scale polyurethane adhesive having an interface bonding strength ≥ 8 MPa; e. The arch support structure is embedded in the middle of the insole and is composed of a POE high-elastic material support sheet.

2. The hybrid insole with dual functions of high elasticity and shock absorption according to claim 1, characterized in that: The POE high-elastic material of the forefoot material is prepared by a twin-screw extruder, and the extrusion temperature is controlled in sections as 160°C in the feeding section, 180°C in the compression section, 190°C in the homogenization section, and 185°C in the die head, and the sheet thickness is 2.5±0.2mm; the surface of the forefoot material is plasma treated, the surface energy is ≥60mN / m, and laser micropores of 10-20μm are formed.

3. The hybrid insole with dual functions of high elasticity and shock absorption according to claim 1, characterized in that: The microporous EVA shock-absorbing material of the heel material is prepared by a compression foaming process with a foaming pressure of 8 MPa, a temperature of 160° C., a foaming ratio of 3.5 times, and a pore size distribution of 100-200 μm; the EVA shock-absorbing material premix contains a foaming agent AC-3000 (3wt%) and a cross-linking agent DCP (0.8wt%).

4. The hybrid insole with dual functions of high elasticity and shock absorption according to claim 1, characterized in that: The gradient transition zone is locally softened at the junction of the POE high elastic material and the EVA shock absorbing material by a hot air gun, and the temperature is controlled at 120° C. to form a mechanical gradient interface in which molecular chains interpenetrate.

5. The hybrid insole with dual functions of high elasticity and shock absorption according to claim 1, characterized in that: The nano-scale polyurethane adhesive of the bonding layer has a coating amount of 20g / m² and is activated by a hot pressing process at 160±5°C and 6MPa pressure, with a holding time of 40 seconds.

6. The hybrid insole with dual functions of high elasticity and shock absorption according to claim 1, characterized in that: The POE high-elastic material support sheet of the arch support structure has a thickness of 1.2-1.8 mm, and its surface is polished with a sand belt to a roughness of ≤Ra3.2 μm.

7. A method for preparing a hybrid insole according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1. Preparation of forefoot material: POE high elastic material is extruded into shape by a twin-screw extruder, and then plasma treated and laser micro-pore etched; S2, preparation of heel material: mixing EVA shock absorbing material with foaming agent and cross-linking agent, and then performing mold foaming, and ripening for 24 hours; S3, composite bonding: After coating the forefoot and heel materials with nano adhesive, hot pressing and bonding at 160±5℃ and 6MPa, and removing bubbles by vacuum adsorption; S4, compression molding: placing the composite sheet in a mold, hydraulically molding at 120°C and 12MPa, and demolding after cooling to 50°C; S5. Post-processing: laser cutting and trimming, edge chamfering, and testing of springback rate, compression deformation and interface peeling strength.

8. The preparation method according to claim 7, characterized in that: The hot pressing bonding described in S3 uses a multi-layer hot press, the vacuum degree is controlled to be -0.08MPa, and the bonding interface temperature is ≥150°C; the mold design in step (d) includes exhaust grooves (depth 0.2mm, spacing 5mm) and cooling water channels (diameter 6mm, spacing 15mm).

9. The preparation method according to claim 7, characterized in that: The detection in S5 includes: 1) Rebound rate test: ASTM D2632 standard, ball drop height 500mm; 2) Compression deformation test: ISO 3386 standard, pressure 500N maintained for 24 hours; 3) Interface peeling test: ASTM D903 standard, peeling rate 100mm / min.

10. The preparation method according to claim 7, characterized in that: The preparation method also includes an antibacterial mesh composite step: the silver ion antibacterial mesh (weight 150g / m²) and the composite sheet are hot-pressed for a second time at 130°C and 3MPa for 20 seconds, and the mesh surface is pre-coated with hot melt adhesive with a thickness of 0.1mm.

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