A shock-resistant and comfortable EVA sole and preparation method

Abstract

The present invention discloses a shock-resistant and comfortable EVA sole and a preparation method. The sole adopts a gradient foaming structure, with natural latex particles added to the upper layer to improve resilience, and modified carbon nanotubes introduced into the lower layer to enhance impact dissipation. A honeycomb-wave composite structure is provided in the heel area to disperse longitudinal stress, and three damping units filled with shear-thickening fluid are embedded in the forefoot area to suppress high-frequency vibrations. The positioning grooves are mechanically interlocked to strengthen the bonding force between the layers, and the surface modification coating and hemispherical protrusions synergistically improve the anti-slip and wear resistance. The preparation method realizes density gradient control through double-layer co-pressure foaming, the gear-rack deflection mechanism of the spraying equipment adapts to the groove for glue coating, a mechanical baffle quickly prevents glue dripping, and a hot pressing bonding process is combined to ensure assembly accuracy. The present invention optimizes dynamic cushioning performance, ensures structural reliability, and significantly improves manufacturing efficiency and product life.

Description

Technical Field

[0001] The invention relates to the technical field of EVA soles, in particular to a shock-resistant and comfortable EVA sole and a preparation method thereof. Background Art

[0002] EVA soles refer to soles made of EVA materials, which have good rebound performance, high tension resistance, high toughness and other characteristics. They have good shockproof and cushioning properties, and excellent thermal insulation, cold resistance and low temperature performance.

[0003] At present, China's patent application number: CN202420640600.3 discloses an EVA sole with high shock resistance and comfort, including an EVA sole, a receiving cavity is opened inside the arch area of ​​the EVA sole, and a dehumidification box is installed inside the receiving cavity, a number of activated carbons are placed inside the dehumidification box, a number of air inlets are opened on the top of the dehumidification box, a plug plate is installed on one side of the dehumidification box, and the plug plate and the receiving cavity can be engaged with each other, and a number of air holes are opened inside the EVA sole directly above the dehumidification box.

[0004] However, the cushioning performance of traditional EVA soles in the existing technology is relatively simple. It is difficult to balance impact absorption and energy rebound through the homogeneous foaming structure, which leads to sports fatigue. When using multi-layer composite materials, it relies on adhesive bonding, which is prone to interlayer peeling after long-term use. Moreover, most of the glue is applied manually, resulting in a waste of human resources. The prepared sole structure is insufficiently reliable and has poor manufacturing precision. Summary of the Invention

[0005] The object of the present invention is to provide a shock-resistant and comfortable EVA sole and a preparation method thereof, so as to solve the problems raised in the above-mentioned background technology.

[0006] In order to achieve the above object, the present invention adopts the following technical scheme: a shock-resistant and comfortable EVA sole, comprising a lower EVA foam layer, wherein the lower EVA foam layer is formed by integrating two foam layers through co-pressing: the foam layer located on the upper layer is formed by blending 88-92wt% of EVA matrix material, 5-8wt% of natural latex particles, 1.0-2.0wt% of azodicarbonamide foaming agent and 0.2-0.5wt% of dicumyl peroxide crosslinking agent, with a foaming rate of 35%-45% and a density of 0.18-0.25g / cm 3 The natural latex particles have a particle size of 50-150 μm; the foaming layer located at the bottom is formed by blending 97.5-98.5wt% of EVA matrix material, 0.3-0.5wt% of carbon nanotubes modified with silane coupling agent, and 1.0-2.0wt% of zinc oxide whiskers, with a foaming rate of 25%-35% and a density of 0.20-0.30 g / cm 3, the bottom surface is distributed with hemispherical protrusions with a diameter of 2-3mm and a height of 0.5-1.2mm; the heel area of ​​the lower EVA foam layer is hot-pressed with a heel structure, and the forefoot area of ​​the lower EVA foam layer is respectively provided with three independent grooves from front to back, and the three grooves are respectively hot-pressed with a first damping unit, a second damping unit and a third damping unit; an upper EVA foam layer for covering the first damping unit, the second damping unit and the third damping unit is hot-pressed above the lower EVA foam layer, and the foaming rate of the upper EVA foam layer is 15%-25%, and the density is 0.25-0.35g / cm 3 .

[0007] Preferably, a positioning groove is provided above the middle portion of the lower EVA foam layer, and a convex column is integrally formed at a position corresponding to the positioning groove on the bottom of the upper EVA foam layer, and the convex column is inserted and connected to the interior of the positioning groove.

[0008] Preferably, the first damping unit, the second damping unit and the third damping unit are all composed of a TPU cavity, and the interior of the TPU cavity is filled with nano-silica-based shear thickening fluid.

[0009] Preferably, the heel structure comprises, from bottom to top, a wave-shaped support body, a honeycomb hole unit and a foam top layer, and the top side of the foam top layer is flush with the top side of the upper EVA foam layer.

[0010] Preferably, the outer surface of the bottom of the lower EVA foam layer is coated with a carbon nanotube / silicone rubber composite coating with a thickness of 0.2-0.4 mm.

[0011] In addition, the present invention also provides a method for preparing the above-mentioned shock-resistant and comfortable EVA sole, comprising the following steps:

[0012] S1. An upper layer mixture containing 5-8 wt% of natural latex particles and a lower layer mixture containing 0.3-0.5 wt% of modified carbon nanotubes are simultaneously loaded into a co-pressing mold, and a pressure of 10 MPa to 15 MPa is applied for co-pressing and foaming for 10 to 12 minutes at an upper layer temperature of 142° C. to 144° C. and a lower layer temperature gradient of 136° C. to 140° C. to form an integrated lower EVA foam layer.

[0013] S2. Rolling the lower surface of the molded lower EVA foam layer to form a hemispherical protrusion with a diameter of 2 mm to 3 mm and a height of 0.5 mm to 1.2 mm;

[0014] S3. Place the prefabricated wave support body and honeycomb cell assembly in the heel area of ​​the lower EVA foam layer, and hot-press bond them at 145° C. to 155° C. and 1.0 MPa to 1.5 MPa for 30 to 45 seconds to form a heel structure;

[0015] S4. Process three independent grooves in the forefoot area of ​​the lower EVA foam layer with a depth of 60% to 70% of the layer thickness. Use a spray coating device to spray polyurethane hot melt adhesive into the independent grooves. Then, insert the first, second, and third damping units filled with nano-silica-based shear thickening fluid into the grooves and hot-press and fuse them at 155°C to 165°C and 0.8 MPa to 1.0 MPa.

[0016] S5. Spray polyurethane hot melt adhesive on the bottom surface of the upper EVA foam layer, align it with the lower EVA foam layer through the positioning groove, and hot press and laminate at 165° C. to 175° C. and 1.0 MPa to 1.5 MPa;

[0017] S6. Use a 60kV to 70kV electrostatic spraying process to form a carbon nanotube / silicone rubber composite coating on the outer surface of the lower EVA foam layer.

[0018] Preferably, the silane coupling agent for modifying the carbon nanotubes is KH-550, and the added amount is 1.5% to 2.0% of the mass of the carbon nanotubes.

[0019] Preferably, the spraying equipment includes a first vertical frame, a shift seat is longitudinally slidably connected to the right side of the first vertical frame, the right side of the shift seat is inserted into and slides inside the second vertical frame, a gluing structure is fastened to the bottom side of the shift seat, a glue spraying head is provided through the middle side of the bottom of the gluing structure, a drip-proof structure is provided below the glue spraying head, the upper and lower sides of the top of the drip-proof structure are respectively fastened to the first vertical frame and the shift seat, the first vertical frame and the second vertical frame are installed above the conveyor belt for conveying soles, a driving cylinder is connected to the middle side of the top of the shift seat, and the top of the glue spraying head is connected to the external polyurethane hot melt adhesive end through a hose.

[0020] Preferably, the glue coating structure includes a bracket fastened to the shift seat on the right side, a cylinder connected to the left rear part of the bracket, a rack connected to the output shaft at the bottom of the cylinder, a gear meshing with the right side of the rack, a cross fixed on the middle side of the gear, and a U-shaped frame connected to the left and right sides of the cross. The front and rear sides of the cross are rotatably connected to the bracket, a glue spray head is provided through the middle side of the bottom of the U-shaped frame, a limit block is provided at the rear left side of the cross, and the rack is longitudinally slidably connected to the right side of the rear of the limit block.

[0021] The lockhole that is formed on the upper part of the second rim is formed on the upper part of the second rim, and the lockhole that is formed on the upper part of the second rim is formed on the upper part of the second rim.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] The present invention organically combines the high rebound characteristics of natural latex particles with the impact dissipation function enhanced by carbon nanotubes through the coordinated design of the gradient foamed EVA layer and the bionic cushioning structure, forming a dynamic energy management system; during the foot contact phase, the latex particles in the upper foaming layer efficiently absorb impact energy through micro-airbag deformation, while the honeycomb-wave composite structure disperses longitudinal stress through a bionic mechanical conduction path, significantly improving the energy rebound rate of the heel area, and the non-Newtonian effect of the shear thickening fluid in the forefoot area accurately suppresses high-frequency vibration transmission, thereby achieving full process optimization from impact absorption to energy release, effectively alleviating sports fatigue and enhancing joint protection.

[0024] This invention is based on the innovative combination of a double-layer co-pressing integrated molding process and a positioning groove mechanical interlocking system. The lower EVA foam layer eliminates the risk of interlayer delamination in traditional multi-layer soles under the dual effects of molecular chain interpenetration and mechanical anchoring; the surface modified coating is electrostatically sprayed with directionally arranged carbon nanotubes, combined with the bionic drainage design of hemispherical protrusions, to maintain the same friction coefficient on wet and slippery roads as in dry environments, thereby improving durability and safety.

[0025] The present invention optimizes the use of spraying equipment in the preparation method, and realizes adaptive coverage of the curved groove by the glue spray head through the precise coordination of the gear-rack deflection mechanism; the mechanically linked drip-proof structure uses a purely mechanical response mechanism of the baffle frame closure to block the baffle frame under the glue spray head after glue spraying to avoid glue dripping and contamination; combined with the gradient temperature co-pressure foaming and hot pressing bonding process, the qualified rate of product molding is improved, and the performance of the sole is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a structural schematic diagram of the present invention;

[0027] Figure 2 For the present invention Figure 1 Schematic diagram of the structure after removing the upper EVA foam layer;

[0028] Figure 3 It is a structural schematic diagram of the heel structure of the present invention;

[0029] Figure 4 It is a structural schematic diagram of the spray coating equipment of the present invention;

[0030] Figure 5 It is a structural schematic diagram of the glue coating structure of the present invention;

[0031] Figure 6 Schematic diagram of the structure of the drip-proof structure of the present invention;

[0032] Figure 7 For the present invention Figure 6 Schematic diagram of the three-dimensional structure.

[0033] In the figure: lower EVA foam layer-1, heel structure-2, upper EVA foam layer-3, first damping unit-11, second damping unit-12, third damping unit-13, positioning groove-14, wavy support body-21, honeycomb hole unit-22, foam top layer-23, first stand-4, shift seat-5, second stand-6, glue coating structure-7, glue spray head-8, drip-proof structure-9, bracket-71, cylinder-72, rack-73, gear-74, cross-75, U-shaped frame-76, limit block-751, first positioning block-91, first screw-92, pull frame-93, second screw-94, rotating shaft rod-95, stop frame-96, first slot piece-97, second slot piece-98, second positioning block-99. DETAILED DESCRIPTION

[0034] In order to further explain the technical solution of the present invention, specific embodiments are described in detail below.

[0035] Example 1:

[0036] See also Figure 1-Figure 3 The present invention provides a shock-resistant and comfortable EVA sole, comprising a lower EVA foam layer 1, wherein the lower EVA foam layer 1 is formed by integrating two foam layers through co-pressing molding:

[0037] The raw material ratio of the upper foaming layer is: EVA particles (brand V6110M) 92wt%, natural latex particles (particle size 80-100μm) 6.5wt%, azodicarbonamide foaming agent 1.2wt%, dicumyl peroxide (DCP) crosslinking agent 0.3wt%;

[0038] The raw material ratio of the foaming layer located at the bottom layer is: EVA particles (V6110M) 97.8wt%, KH-550 modified carbon nanotubes (diameter 20-30nm, aspect ratio 1200) 0.4wt%, zinc oxide whiskers 1.8wt%;

[0039] The heel area of ​​the lower EVA foam layer 1 is hot-pressed with a heel structure 2 to achieve a gradient conduction of the impact force from the heel to the forefoot. The forefoot area of ​​the lower EVA foam layer 1 is provided with three independent grooves from front to back, and the three grooves are hot-pressed with a first damping unit 11, a second damping unit 12 and a third damping unit 13. The partitioned damping design adapts to the pressure distribution in different gait stages. The upper EVA foam layer 3 for covering the first damping unit 11, the second damping unit 12 and the third damping unit 13 is hot-pressed above the lower EVA foam layer 1. The foaming rate of the upper EVA foam layer 3 is 15%-25%, and the density is 0.30g / cm 3 The low foaming rate upper layer provides stable support, and the wrap-around design prevents the damping unit from displacing.

[0040] Among them, a positioning groove 14 is opened above the middle position of the lower EVA foam layer 1, and a convex column is integrally formed at the position corresponding to the positioning groove 14 at the bottom of the upper EVA foam layer 3, and the convex column is inserted and connected to the inside of the positioning groove 14, and the interlayer bonding strength is improved through the mechanical interlocking structure. The first damping unit 11, the second damping unit 12 and the third damping unit 13 are all composed of a TPU cavity, and the TPU cavity is filled with nano-silica-based shear thickening fluid. The shear thickening effect instantly hardens under high impact and effectively absorbs high-frequency vibrations. The heel structure 2 includes a wavy support body 21, a honeycomb hole unit 22 and a foam top layer 23 from bottom to top. The top side of the foam top layer 23 is flush with the top side of the upper EVA foam layer 3. The wavy support body disperses the longitudinal impact force, and the honeycomb unit improves the energy rebound rate. The outer surface of the bottom of the lower EVA foam layer 1 is covered with a carbon nanotube / silicone rubber composite coating with a thickness of 0.2-0.4mm. The directionally arranged carbon nanotubes can reduce the surface friction coefficient and enhance the waterproof performance.

[0041] See also Figure 4-Figure 7 The present invention provides a method for preparing the above-mentioned shock-resistant and comfortable EVA sole, comprising the following steps:

[0042] S1. An upper layer mixture containing 6.5 wt% natural latex particles and a lower layer mixture containing 0.4 wt% modified carbon nanotubes are simultaneously loaded into a co-pressing mold. An initial pressure of 12 MPa is applied at a temperature gradient of 142°C to 144°C for the upper layer and 136°C to 140°C for the lower layer. The pressure is reduced to 8 MPa during the holding phase. The total foaming time is 11 minutes and 30 seconds to form an integrated lower EVA foam layer 1. Density differentiation is achieved by temperature gradient control, and interlayer delamination can be avoided by using a co-pressing process.

[0043] S2. Roll the lower surface of the molded lower EVA foam layer 1 to form a hemispherical protrusion with a diameter of 2.5 mm ± 0.1 mm and a height of 1.0 mm ± 0.05 mm;

[0044] S3. Place the prefabricated wave support body 21 and honeycomb cell unit 22 assembly in the heel area of ​​the lower EVA foam layer 1 and perform hot pressing and bonding at 150° C. and 1.2 MPa for 35 seconds to form the heel structure 2. Hot pressing and bonding allows the molecular chains on the interface to diffuse and fuse, thereby increasing the bonding strength.

[0045] S4. Three independent grooves with a depth of 65% of the layer thickness are machined in the forefoot area of ​​the lower EVA foam layer 1. Polyurethane hot-melt adhesive is sprayed into the independent grooves using a spraying device. The first damping unit 11, the second damping unit 12, and the third damping unit 13 filled with a nano-silica-based shear thickening fluid are then inserted into the grooves and hot-pressed and fused at 160°C ± 2°C and 0.9 MPa. The pre-coating of hot-melt adhesive enhances the adhesion between the TPU and the EVA and improves the peel strength.

[0046] S5. Spray polyurethane hot melt adhesive on the bottom surface of the upper EVA foam layer 3, align it with the lower EVA foam layer 1 through the positioning grooves 14, and hot press laminate it at 168°C ± 2°C and 1.2 MPa. The positioning grooves 14 reduce the error in inter-layer alignment and ensure structural symmetry.

[0047] S6. A carbon nanotube / silicone rubber composite coating is formed on the outer surface of the lower EVA foam layer 1 using a 65kV electrostatic spraying process with a spray distance of 180mm and a film thickness of 0.28mm. Electrostatic spraying is used to orient the carbon nanotubes and optimize the conductivity and wear resistance of the coating.

[0048] Among them, the silane coupling agent for modifying carbon nanotubes is KH-550, and the addition amount is 1.8% of the mass of carbon nanotubes. KH-550 modification eliminates carbon nanotube agglomeration and enhances the interface bonding strength with EVA.

[0049] Among them, the spraying equipment includes a first stand 4, and a shift seat 5 is longitudinally slidably connected to the right side of the first stand 4. The right side of the shift seat 5 is inserted and slid inside the second stand 6, and three-dimensional precise positioning is achieved through the double stand guide rails. A gluing structure 7 is fastened to the bottom side of the shift seat 5, and a glue spraying head 8 is provided through the middle side of the bottom of the gluing structure 7. A drip-proof structure 9 is provided below the glue spraying head 8. The upper and lower sides of the top of the drip-proof structure 9 are fastened to the first stand 4 and the shift seat 5 respectively. The first stand 4 and the second stand 6 are installed above the conveyor belt for conveying the soles. The drip-proof structure 9 prevents the residual glue on the gluing structure 7 from dripping onto the soles, thereby ensuring the quality of the sole preparation. A driving cylinder is connected to the middle side of the top of the shift seat 5 to change the height of the longitudinal position of the shift seat 5 under the action of the driving cylinder. The top of the glue spraying head 8 is connected to the external polyurethane hot melt adhesive end through a hose, so that the polyurethane hot melt adhesive is sprayed onto the soles through the glue spraying head 8.

[0050] Among them, the glue coating structure 7 includes a bracket 71 fastened to the shift seat 5 on the right side, a cylinder 72 connected to the left rear part of the bracket 71, a rack 73 connected to the output shaft at the bottom of the cylinder 72, a gear 74 meshing with the right side of the rack 73, a cross 75 fixed on the middle side of the gear 74, and a U-shaped frame 76 connected to the left and right sides of the cross 75. The front and rear sides of the cross 75 are rotatably connected to the bracket 71, and a glue head 8 is provided through the middle side of the bottom of the U-shaped frame 76. A limit block 751 is provided on the left rear part of the cross 75, and the rack 73 is longitudinally slidably connected to the right rear side of the limit block 751. The rack 73 is driven by the cylinder 72 to drive the gear 74 to rotate, and then the angle of the U-shaped frame 76 is adjusted through the cross 75 to realize the position deflection of the glue head 8 to adapt to the spraying of curved grooves.

[0051] The anti-drip structure 9 includes a first positioning block 91 fastened to the shift seat 5 on the top side, a first screw 92 rotatably connected to the inner side of the first positioning block 91, a pull frame 93 threadedly connected to the bottom side of the outer surface of the first screw 92, a second screw 94 threadedly connected to the middle side of the bottom of the pull frame 93, a rotating shaft rod 95 rotatably connected to the bottom of the second screw 94, and a baffle 96 connected to the front and rear sides of the rotating shaft rod 95. The positions of the first screw 92 and the second screw 94 in the pull frame 93 are adjusted so that the rotating shaft rod 95 drives the initial tilt position of the baffle 96 to be adjusted so that the baffle 96 is initially located below the glue spraying head 8. The two first slots 97 rotatably connected to the front and rear sides of the baffle 96 are respectively connected The two second slot pieces 98 connected to the upper part of the two first slot pieces 97 close to the side of the retaining frame 96 and the second positioning block 99 rotatably connected to the top of the inner side of the two second slot pieces 98, the front and rear sides of the rotating shaft rod 95 are respectively penetrated into the two first slot pieces 97, the top of the first slot piece 97 is penetrated into the second slot piece 98 by a bolt rod and a nut, and the bottom of the second slot piece 98 is penetrated into the first slot piece 97 by a bolt rod and a nut. The right side of the second positioning block 99 is fastened to the first upright frame 4, so as to support the retaining frame 96 on one side through the cooperation of the first slot piece 97 and the second slot piece 98, so that the retaining frame 96 moves obliquely downward to the left after being subjected to downward pressure.

[0052] The working principle of the spraying equipment is as follows:

[0053] First, the spray coating equipment is installed above the conveyor belt for conveying shoe soles through the first stand 4 and the second stand 6. When the shoe sole passes the bottom, the driving cylinder drives the shift seat 5 to slide longitudinally along the first stand 4 and the second stand 6, so that the glue coating structure 7 drives the glue spray head 8 to move down close to the shoe sole;

[0054] Second, during the downward movement of the shift seat 5, the first screw 92, the second screw 94 and the pull frame 93 drive the retaining frame 96 to move obliquely downward to the left under the support of the first slot 97 and the second slot 98, so that the retaining frame 96 moves away from the bottom of the glue spray head 8;

[0055] Third, the cylinder 72 drives the rack 73 to rotate the gear 74, so that the gear 74 drives the cross 75 to rotate on the bottom side of the bracket 71. The cross 75 is used to adjust the angle of the U-shaped frame 76 to achieve the position deflection of the glue spray head 8 to adapt to the spraying of curved grooves;

[0056] Fourth, after the glue coating is completed, the shift seat 5 moves upward, and under the action of the first screw 92, the second screw 94 and the pull frame 93, the blocking frame 96 is lifted up again to block the bottom of the glue spraying head 8.

[0057] Example 2:

[0058] See also Figure 1-Figure 3The present invention provides a shock-resistant and comfortable EVA sole, comprising a lower EVA foam layer 1, wherein the lower EVA foam layer 1 is formed by integrating two foam layers through co-pressing molding:

[0059] The raw material ratio of the upper foaming layer is: EVA particles (brand V6110M) 88wt%, natural latex particles (particle size 120-150μm) 8wt%, azodicarbonamide foaming agent 1.0wt%, dicumyl peroxide (DCP) crosslinking agent 0.2wt%;

[0060] The raw material ratio of the foaming layer located at the bottom layer is: EVA particles (V6110M) 97.5wt%, KH-550 modified carbon nanotubes (diameter 20-30nm, aspect ratio 1200) 0.3wt%, zinc oxide whiskers 2.0wt%;

[0061] The heel area of ​​the lower EVA foam layer 1 is hot-pressed with a heel structure 2 to achieve a gradient conduction of the impact force from the heel to the forefoot. The forefoot area of ​​the lower EVA foam layer 1 is provided with three independent grooves from front to back, and the three grooves are hot-pressed with a first damping unit 11, a second damping unit 12 and a third damping unit 13. An upper EVA foam layer 3 for covering the first damping unit 11, the second damping unit 12 and the third damping unit 13 is hot-pressed above the lower EVA foam layer 1. The upper EVA foam layer 3 has a foaming rate of 25% and a density of 0.25 g / cm 3 .

[0062] Among them, a positioning groove 14 is opened above the middle position of the lower EVA foam layer 1, and a convex column is integrally formed at the position corresponding to the positioning groove 14 at the bottom of the upper EVA foam layer 3, and the convex column is inserted and connected to the inside of the positioning groove 14. The first damping unit 11, the second damping unit 12 and the third damping unit 13 are all composed of a TPU cavity, and the inside of the TPU cavity is filled with nano-silica-based shear thickening fluid. The heel structure 2 includes a wavy support body 21, a honeycomb hole unit 22 and a foam top layer 23 from bottom to top. The top side of the foam top layer 23 is flush with the top side of the upper EVA foam layer 3. The outer surface of the bottom of the lower EVA foam layer 1 is covered with a carbon nanotube / silicone rubber composite coating with a thickness of 0.4 mm, and the KH-550 addition amount is 1.5% of the mass of the carbon nanotubes.

[0063] The method for preparing the shock-resistant and comfortable EVA sole comprises the following steps:

[0064] S1. An upper layer mixture containing 8 wt% of natural latex particles and a lower layer mixture containing 0.3 wt% of modified carbon nanotubes are simultaneously loaded into a co-pressing mold, and a pressure of 15 MPa is applied for co-pressing and foaming for 12 minutes under a temperature gradient of 142° C. for the upper layer and 136° C. for the lower layer to form an integrated lower EVA foam layer 1.

[0065] S2, rolling the lower surface of the molded lower EVA foam layer 1 to form a hemispherical protrusion with a diameter of 3.0 mm and a height of 0.5 mm;

[0066] S3, placing the prefabricated wave support body 21 and honeycomb cell unit 22 assembly on the heel area of ​​the lower EVA foam layer 1, and hot pressing and bonding them at 145° C. and 1.0 MPa pressure for 45 seconds to form the heel structure 2;

[0067] S4. Three independent grooves with a depth of 65% of the layer thickness are machined in the forefoot area of ​​the lower EVA foam layer 1. Polyurethane hot melt adhesive is sprayed into the independent grooves using a spray coating device. The first damping unit 11, the second damping unit 12, and the third damping unit 13 filled with a nano-silica-based shear thickening fluid are then embedded in the grooves and hot-pressed and fused at 155°C and 0.8 MPa.

[0068] S5. Spray polyurethane hot melt adhesive on the bottom surface of the upper EVA foam layer 3, align it with the lower EVA foam layer 1 through the positioning groove 14, and hot press and laminate at 165°C and 1.0 MPa pressure;

[0069] S6. A carbon nanotube / silicone rubber composite coating is formed on the outer surface of the lower EVA foam layer 1 using a 60 kV electrostatic spraying process, with a spray distance of 180 mm and a film thickness of 0.4 mm.

[0070] Effect: The high foaming rate design significantly improves resilience, and the large-size latex particles enhance interfacial stress dispersion, making it suitable for high-intensity sports scenes.

[0071] Example 3:

[0072] See also Figure 1-Figure 3 The present invention provides a shock-resistant and comfortable EVA sole, comprising a lower EVA foam layer 1, wherein the lower EVA foam layer 1 is formed by integrating two foam layers through co-pressing molding:

[0073] The raw material ratio of the upper foaming layer is: EVA particles (brand V6110M) 92wt%, natural latex particles (particle size 50-80μm) 5wt%, azodicarbonamide foaming agent 2.0wt%, dicumyl peroxide (DCP) crosslinking agent 0.5wt%;

[0074] The raw material ratio of the foaming layer located at the bottom layer is: EVA particles (V6110M) 98.5wt%, KH-550 modified carbon nanotubes (diameter 20-30nm, aspect ratio 1200) 0.5wt%, zinc oxide whiskers 1.0wt%;

[0075] The heel area of ​​the lower EVA foam layer 1 is hot-pressed with a heel structure 2 to achieve a gradient conduction of the impact force from the heel to the forefoot. The forefoot area of ​​the lower EVA foam layer 1 is provided with three independent grooves from front to back, and the three grooves are hot-pressed with a first damping unit 11, a second damping unit 12 and a third damping unit 13. The upper EVA foam layer 3 for covering the first damping unit 11, the second damping unit 12 and the third damping unit 13 is hot-pressed above the lower EVA foam layer 1. The foaming rate of the upper EVA foam layer 3 is 15% and the density is 0.35g / cm 3 .

[0076] Among them, a positioning groove 14 is opened above the middle position of the lower EVA foam layer 1, and a convex column is integrally formed at the position corresponding to the positioning groove 14 at the bottom of the upper EVA foam layer 3, and the convex column is inserted and connected to the inside of the positioning groove 14. The first damping unit 11, the second damping unit 12 and the third damping unit 13 are all composed of a TPU cavity, and the inside of the TPU cavity is filled with nano-silica-based shear thickening fluid. The heel structure 2 includes a wavy support body 21, a honeycomb hole unit 22 and a foam top layer 23 from bottom to top. The top side of the foam top layer 23 is flush with the top side of the upper EVA foam layer 3. The outer surface of the bottom of the lower EVA foam layer 1 is covered with a carbon nanotube / silicone rubber composite coating with a thickness of 0.2 mm, and the KH-550 addition amount is 2.0% of the mass of the carbon nanotubes.

[0077] The method for preparing the shock-resistant and comfortable EVA sole comprises the following steps:

[0078] S1. An upper layer mixture containing 8 wt% natural latex particles and a lower layer mixture containing 0.5 wt% modified carbon nanotubes are simultaneously loaded into a co-pressing mold, and a pressure of 10 MPa is applied for co-pressing and foaming for 10 minutes under a temperature gradient of 144° C. for the upper layer and 140° C. for the lower layer to form an integrated lower EVA foam layer 1.

[0079] S2, rolling the lower surface of the molded lower EVA foam layer 1 to form a hemispherical protrusion with a diameter of 2.0 mm and a height of 1.2 mm;

[0080] S3, placing the prefabricated wave support body 21 and honeycomb cell unit 22 assembly on the heel area of ​​the lower EVA foam layer 1, and hot pressing and bonding them at 155° C. and 1.5 MPa pressure for 30 seconds to form the heel structure 2;

[0081] S4. Three independent grooves with a depth of 65% of the layer thickness are machined in the forefoot area of ​​the lower EVA foam layer 1. Polyurethane hot melt adhesive is sprayed into the independent grooves using a spray coating device. The first damping unit 11, the second damping unit 12, and the third damping unit 13 filled with a nano-silica-based shear thickening fluid are then embedded in the grooves and hot-pressed and fused at 165°C and 1.0 MPa.

[0082] S5. Spray polyurethane hot melt adhesive on the bottom surface of the upper EVA foam layer 3, align it with the lower EVA foam layer 1 through the positioning groove 14, and hot press and laminate it at 175°C and 1.5 MPa pressure;

[0083] S6. A carbon nanotube / silicone rubber composite coating is formed on the outer surface of the lower EVA foam layer 1 using a 70 kV electrostatic spraying process, with a spray distance of 180 mm and a film thickness of 0.2 mm.

[0084] Effect: Low foaming rate combined with high cross-linking agent dosage enhances the structural rigidity of the sole, while small-size latex particles improve material uniformity and optimize the cushioning comfort of daily walking.

[0085] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to substitute equivalents for some of the technical features. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A shock-resistant and comfortable EVA sole, characterized in that: The invention comprises a lower EVA foam layer (1), wherein the lower EVA foam layer (1) is formed by integrating two foam layers through co-pressing: the foam layer located on the upper layer is formed by blending and foaming 88-92 wt% of EVA matrix material, 5-8 wt% of natural latex particles, 1.0-2.0 wt% of azodicarbonamide foaming agent and 0.2-0.5 wt% of diisopropylbenzene peroxide crosslinking agent, with a foaming rate of 35%-45% and a density of 0.18-0.25 g / cm 3 The natural latex particles have a particle size of 50-150 μm; the foaming layer located at the bottom is formed by blending 97.5-98.5wt% of EVA matrix material, 0.3-0.5wt% of carbon nanotubes modified with silane coupling agent, and 1.0-2.0wt% of zinc oxide whiskers, with a foaming rate of 25%-35% and a density of 0.20-0.30 g / cm 3 , with hemispherical protrusions distributed on the bottom surface, the protrusions having a diameter of 2-3 mm and a height of 0.5-1.2 mm; the heel region of the lower EVA foam layer (1) is hot-pressed with a heel structure (2); the forefoot region of the lower EVA foam layer (1) is respectively provided with three independent grooves from front to back, and the three grooves are respectively hot-pressed with a first damping unit (11), a second damping unit (12) and a third damping unit (13); an upper EVA foam layer (3) for covering the first damping unit (11), the second damping unit (12) and the third damping unit (13) is hot-pressed above the lower EVA foam layer (1); the upper EVA foam layer (3) has a foaming rate of 15%-25% and a density of 0.25-0.35 g / cm 3 A positioning groove (14) is provided above the middle portion of the lower EVA foam layer (1), and a convex column is integrally formed at a position corresponding to the positioning groove (14) on the bottom of the upper EVA foam layer (3), and the convex column is inserted and connected to the interior of the positioning groove (14); the first damping unit (11), the second damping unit (12) and the third damping unit (13) are all composed of a TPU cavity, and the interior of the TPU cavity is filled with a nano-silica-based shear thickening fluid; the outer surface of the bottom of the lower EVA foam layer (1) is covered with a carbon nanotube / silicone rubber composite coating with a thickness of 0.2-0.4 mm.

2. The shock-resistant and comfortable EVA sole according to claim 1, characterized in that: The heel structure (2) comprises, from bottom to top, a wave-shaped support body (21), a honeycomb hole unit (22), and a foam top layer (23), wherein the top side of the foam top layer (23) is flush with the top side of the upper EVA foam layer (3).

3. A method for preparing a shock-resistant and comfortable EVA sole, for preparing the shock-resistant and comfortable EVA sole according to any one of claims 1 to 2, characterized in that: The steps include: S1. An upper layer mixture containing 5-8 wt% of natural latex particles and a lower layer mixture containing 0.3-0.5 wt% of modified carbon nanotubes are simultaneously loaded into a co-pressing mold, and a pressure of 10 MPa to 15 MPa is applied for co-pressing and foaming for 10 to 12 minutes at an upper layer temperature of 142°C to 144°C and a lower layer temperature gradient of 136°C to 140°C to form an integrated lower EVA foaming layer (1); S2, rolling the lower surface of the molded lower EVA foam layer (1) to form a hemispherical protrusion with a diameter of 2 mm to 3 mm and a height of 0.5 mm to 1.2 mm; S3, placing the prefabricated wave support body (21) and honeycomb cell unit (22) assembly on the heel area of ​​the lower EVA foam layer (1), and hot pressing and bonding them at 145° C. to 155° C. and 1.0 MPa to 1.5 MPa for 30 seconds to 45 seconds to form the heel structure (2); S4, processing three independent grooves with a depth of 60% to 70% of the layer thickness in the forefoot area of ​​the lower EVA foam layer (1), spraying polyurethane hot melt adhesive in the independent grooves by spraying equipment, and then embedding the first damping unit (11), the second damping unit (12) and the third damping unit (13) filled with nano-silica-based shear thickening fluid into the grooves, and hot pressing and fusing them at 155°C to 165°C and 0.8MPa to 1.0MPa; S5, spraying polyurethane hot melt adhesive on the bottom surface of the upper EVA foam layer (3), aligning it with the lower EVA foam layer (1) through the positioning groove (14), and hot pressing and laminating at 165°C to 175°C and 1.0MPa to 1.5MPa; S6. Using a 60kV to 70kV electrostatic spraying process, a carbon nanotube / silicone rubber composite coating is formed on the outer surface of the lower EVA foaming layer (1).

4. The method for preparing a shock-resistant and comfortable EVA sole according to claim 3, wherein: The silane coupling agent for modifying the carbon nanotubes is KH-550, and the addition amount is 1.5% to 2.0% of the mass of the carbon nanotubes.

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