Two-section type sole structure, preparation process thereof and shoe with two-section type sole structure

Abstract

The invention provides a two-section type sole structure, a preparation process thereof and a shoe with the two-section type sole structure, and belongs to the technical field of shoemaking. The two-section type sole structure comprises a front-section foaming outsole, a rear-section foaming outsole and a middle rubber connecting piece for connecting the front-section foaming outsole and the rear-section foaming outsole; and the front section foaming outsole and the rear section foaming outsole are provided with lap joint surfaces in lap joint areas with the middle rubber connecting sheet. By optimizing the hardness, the thickness and the lap joint process of the middle rubber connecting piece, the deflection resistance and the interface bonding durability of the bending area are effectively improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of shoemaking, and particularly relates to a two-segment sole structure and a preparation process thereof, and a shoe with the same. BACKGROUND

[0002] In the shoemaking industry, the foamed material big sole is widely used in sports shoes, casual shoes and women's shoes due to its light weight, shock absorption and comfort.

[0003] However, the traditional integrated foamed big sole is prone to material fatigue, cracking or structural fracture in the long-term use or repeated bending area (such as the metatarsophalangeal joint part), which affects the service life of the shoe. SUMMARY

[0004] To solve at least one aspect of the technical problem in the background art, the application provides a two-segment sole structure, which effectively improves the bending resistance and interface bonding durability of the bending area by optimizing the hardness, thickness and lap joint process of the intermediate rubber connecting sheet.

[0005] The technical scheme adopted by the application is as follows: The first aspect of the application provides a two-segment sole structure, comprising: a front foamed big sole, a rear foamed big sole and an intermediate rubber connecting sheet connecting the front foamed big sole and the rear foamed big sole. The front foamed big sole and the rear foamed big sole are provided with a lap joint surface in the lap joint area with the intermediate rubber connecting sheet.

[0006] According to the two-segment sole structure provided by the first aspect of the application, the traditional integrated foamed big sole is designed in segments in the frequently bending metatarsophalangeal area, effectively decoupling the stress concentration problem in the dynamic stress process: the front segment and the rear segment adopt light weight and high elasticity foamed material (such as EVA or foamed TPU), ensuring the shock absorption and overall light weight of the sole; and the intermediate connecting area is physically connected by an independent rubber connecting sheet, which has flexibility and tear resistance suitable for bending requirements, and can withstand repeated deformation without breaking in each step of walking or movement. The design of the lap joint surface increases the bonding area between the foamed big sole and the rubber connecting sheet, providing a structural basis for subsequent interface treatment and firm combination, not only improving the feasibility of the assembly process, but also significantly enhancing the interlayer bonding strength and durability.

[0007] According to one embodiment of the application, the intermediate rubber connecting sheet has a 1.5 mm non-gluing area reserved at the edge of the bonding area with the front foamed big sole and the rear foamed big sole.

[0008] According to one embodiment of this application, the overlapping surfaces of the front foam outsole and the rear foam outsole are coated with a treatment agent and a water-based adhesive.

[0009] According to one embodiment of this application, the intermediate rubber connecting piece has a hardness of 40 to 45 Shore A and a thickness of 3 mm.

[0010] According to one embodiment of this application, the overlap width of the overlapping surface is 35 mm.

[0011] A second aspect of this application provides a manufacturing process for a two-section shoe sole structure, used to manufacture the two-section shoe sole structure described in any of the embodiments of the first aspect above, comprising: The overlapping surfaces of the front and rear foam outsoles are roughened using a soft wire wheel. Apply a treatment agent to the roughened overlapping surfaces and let them dry, followed by the application of a water-based adhesive; After the water-based adhesive has been left to stand for 24 hours, the middle rubber connecting piece is bonded between the front foam outsole and the rear foam outsole, and a 1.5mm non-adhesive area is reserved at the bonding edge. Pressure is applied to the bonding area using a pressing mold and held to complete the pressing and shaping process.

[0012] According to one embodiment of this application, the roughening treatment of the overlapping surface of the front and rear foam outsoles using a soft wire wheel specifically involves: Using a soft wire wheel with a grit size of 60–80 mesh, the overlapping surfaces are uniformly ground in one direction at a speed of 2800–3200 rpm, with the grinding depth controlled at 0.1–0.15 mm.

[0013] According to one embodiment of this application, the step of applying a treatment agent to the roughened overlapping surface and drying it, followed by applying a water-based adhesive, specifically involves: Apply the treatment agent evenly to the roughened overlapping surface, apply two coats, and allow each coat to dry at room temperature for 5–10 minutes. Apply water-based polyurethane adhesive in two coats, allowing it to stand at room temperature for 10–15 minutes after each coat.

[0014] According to one embodiment of this application, the pressing pressure is 0.6–0.8 MPa, and the holding time is 30–60 seconds.

[0015] A third aspect of this application provides a shoe including a two-section sole structure as described in any of the embodiments of the first aspect. Attached Figure Description

[0016] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings: Figure 1 This is a schematic diagram of the two-section shoe sole structure provided in the embodiments of this application; Figure 2 This is a schematic diagram of the manufacturing process for a two-section shoe sole structure.

[0017] in, 11. Front section foam outsole; 12. Rear section foam outsole; 13. Middle rubber connecting piece. Detailed Implementation

[0018] To more clearly illustrate the overall concept of this application, a detailed explanation is provided below with reference to the accompanying drawings.

[0019] Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application may also be implemented in other ways different from those described herein. Therefore, the scope of protection of this application is not limited to the specific embodiments disclosed below. It should be noted that, unless otherwise specified, the embodiments of this application and the features thereof can be combined with each other.

[0020] Furthermore, it should be understood in the description of this application that the terms "top", "bottom", "inner", "outer", "axial", "radial", "circumferential", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0021] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a communication connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0022] In this application, unless otherwise expressly specified and limited, the "above" or "below" of the second feature can mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. In the description of this specification, references to terms such as "an embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described can be combined in any suitable manner in one or more embodiments or examples.

[0023] like Figure 1 As shown, a first aspect of this application provides a two-section shoe sole structure, including: Front section foam outsole 11, rear section foam outsole 12, and intermediate rubber connecting piece 13 connecting the front section foam outsole 11 and the rear section foam outsole 12; The front section foam outsole 11 and the rear section foam outsole 12 have overlapping surfaces in the overlapping area with the middle rubber connecting piece 13.

[0024] According to the two-section sole structure provided in the first aspect of this application, by segmenting the traditional one-piece foam outsole in the frequently bending metatarsophalangeal region, the stress concentration problem during dynamic stress is effectively decoupled: the front and rear sections use lightweight, highly elastic foam materials (such as EVA or foamed TPU) to ensure the cushioning and overall lightweight of the sole; while the middle connecting area is physically connected by an independent rubber connecting piece. This rubber piece has the flexibility to adapt to bending requirements and tear resistance, and can withstand repeated deformation during each step or movement without easily breaking. The overlapping surface design increases the bonding area between the foam outsole and the rubber connecting piece, providing a structural basis for subsequent interface treatment and firm bonding, which not only improves the feasibility of the assembly process, but also significantly enhances the interlayer bonding strength and durability.

[0025] In some embodiments of this application, the intermediate rubber connecting piece 13 has a 1.5 mm non-adhesive area reserved at the edge of the bonding area with the front foam outsole 11 and the rear foam outsole 12.

[0026] In actual use, the bonding edges of shoe soles are the areas with the most significant stress concentration, especially during repeated bending. Micro-cracks easily form at the interface between the adhesive layer and different materials and gradually expand, eventually leading to delamination or interface peeling. By proactively reserving a 1.5 mm uncoated area at the edge of the bonding area, it is possible to effectively prevent adhesive overflow during the pressing process, avoiding the formation of thick edges or stress concentration points. It also prevents rigid transitions caused by adhesive buildup at the edges, resulting in smoother and more continuous deformation between materials. Furthermore, this uncoated area reduces the risk of edge lifting caused by adhesive aging, thermal expansion and contraction, or moisture penetration, improving the long-term durability of the interface. From a process perspective, this design helps control the precision of adhesive application, preventing excess adhesive from contaminating the mold or affecting the appearance, and improving production consistency.

[0027] In some embodiments of this application, the overlapping surfaces of the front foam outsole 11 and the rear foam outsole 12 are coated with a treatment agent and a water-based adhesive. Because foam outsoles (such as EVA, TPU, etc.) have poor surface density, high porosity, and contain residual release agents, their surface energy is low, making them prone to insufficient adhesion and easy delamination when directly bonded to rubber. By first coating the overlapping surfaces with a treatment agent, the surface can be effectively cleaned, the release layer removed, and the foam material modified to enhance its wettability and chemical bonding with the adhesive. Subsequently, a water-based adhesive is applied, which is not only environmentally friendly and non-toxic, meeting modern green manufacturing requirements, but also possesses good initial tack, flexibility, and resistance to damp heat aging, enabling it to adapt to dynamic stress changes in complex environments. The water-based polyurethane adhesive also forms a strong and tough adhesive film after curing, firmly connecting the porous foam to the dense rubber material, ensuring no interlayer delamination occurs during repeated bending.

[0028] In some embodiments of this application, the intermediate rubber connecting piece 13 has a hardness of 40 to 45 Shore A and a thickness of 3 mm. This parameter design is a key technical feature for achieving the optimal balance between flexibility, support, and durability in a two-piece sole structure. Controlling the hardness within the Shore A range of 40–45 gives the rubber connecting piece moderate elasticity and softness, allowing it to conform to the natural bending of the foot during walking or exercise, effectively alleviating stress concentration in the metatarsophalangeal joint area and avoiding the risk of cracking due to excessive stiffness. It also provides sufficient structural support to prevent excessive deformation that could lead to material fatigue or collapse. Compared to traditional rigid connectors or high-hardness rubbers (such as those above Shore A 60), this hardness range significantly improves wearing comfort and dynamic fit. Simultaneously, the 3 mm thickness design ensures connection strength and dimensional stability while balancing the overall thinness of the sole and space utilization. This thickness is sufficient to withstand the shear and tensile stresses generated by repeated bending and provides ample bonding volume for the overlapping surfaces, enhancing the reliability of the interface bonding. Practice has shown that when the hardness of the rubber connecting piece exceeds this range or the thickness is less than 2 mm, it is very easy for the material to break or the glue to come undone during the flex test. However, by using a Shore hardness of 40–45 and a thickness of 3 mm, combined with optimized processes, the performance of the finished shoe in 30,000 to 40,000 flex tests can be significantly improved, delaying the formation of cracks and meeting the dual requirements of high-end women's shoes for durability and comfort.

[0029] In some embodiments of this application, the overlap width of the overlapping surfaces is 35 mm. In the two-section sole structure, the forefoot foam outsole 11 and the rearfoot foam outsole 12 are bonded together in the overlapping area by a middle rubber connecting piece 13. The overlap width directly affects the bonding area and the interface load-bearing capacity. An overly narrow overlap width will result in insufficient effective bonding area, making it prone to local peeling or delamination due to stress concentration during repeated bending or dynamic stress. On the other hand, an overly wide design will increase material usage, leading to increased sole weight and potentially limiting bending flexibility, thus affecting wearing comfort. Actual testing and process optimization have shown that when the overlap width is set to 35 mm, it provides sufficient bonding contact surface, allowing stress to be evenly distributed along the bonding interface, significantly improving shear and peel resistance, and also adapting to the spatial layout of the transition area from the forefoot to the midfoot in conventional women's shoes or casual shoes, avoiding structural redundancy. This width, combined with surface treatment, special adhesives, and pressing processes, can effectively support the finished shoe to pass high-frequency flexing tests (such as more than 30,000 times), and no obvious material breakage or delamination was observed during two consecutive months of actual wear testing.

[0030] like Figure 2 As shown, a second aspect of this application provides a manufacturing process for a two-section shoe sole structure, used to manufacture the two-section shoe sole structure in any of the embodiments of the first aspect, comprising: Step 100: Roughen the overlapping surfaces of the front and rear foam outsoles with a soft wire wheel.

[0031] Step 200: Apply a treatment agent to the roughened overlapping surfaces and allow them to dry, then apply a water-based adhesive.

[0032] Step 300: After the water-based adhesive has been left to stand for 24 hours, bond the middle rubber connecting piece between the front foam outsole and the rear foam outsole, and leave a 1.5mm non-adhesive area at the bonding edge.

[0033] Step 400: Apply pressure to the bonding area using a pressing mold and maintain the pressure to complete the pressing and shaping.

[0034] Step 100: Roughen the overlapping surfaces of the front and rear foamed outsoles using a soft-grit wheel. Physical grinding removes the surface release agent and smoothing layer, exposing a fresh, porous substrate structure. This significantly increases the specific surface area and mechanical interlocking ability of the bonding interface, providing a good foundation for subsequent adhesive adhesion. Step 200: Apply a treatment agent to the roughened overlapping surfaces and allow them to dry. Then apply a water-based adhesive. The treatment agent further cleans and activates the surface, enhancing material polarity, while the water-based adhesive forms a flexible, aging-resistant adhesive film under environmentally friendly conditions, ensuring adhesion to the foamed material. Both the adhesive and rubber exhibit excellent adhesion properties. In step 300, after applying the adhesive, the mixture is allowed to stand for 24 hours to fully cure and release stress, allowing the adhesive layer to reach its optimal bonding state. Then, the intermediate rubber connecting piece is precisely bonded between the front and rear foamed outsoles, leaving a 1.5mm uncoated area at the bonding edge to effectively avoid stress concentration and edge lifting caused by adhesive layer accumulation, thus improving the stability of the interface under dynamic bending. In step 400, a special pressing mold is used to apply uniform pressure to the bonding area and maintain pressure for a certain time, promoting full wetting and tight adhesion of the adhesive layer, achieving molecular-level bonding, and completing the final pressing and shaping. This preparation process systematically solves the problems of interface compatibility, stress distribution, and long-term durability in the bonding of dissimilar materials. Each step is interconnected and works synergistically, not only improving production consistency and yield but also significantly enhancing the structural reliability of the finished shoe in high-cycle flexing tests and actual wear.

[0035] In some embodiments of this application, the overlapping surfaces of the front and rear foam outsoles are roughened using a soft wire wheel, specifically as follows: Using a soft wire wheel with a grit size of 60–80 mesh, the overlapping surfaces are uniformly ground in one direction at a speed of 2800–3200 rpm, with the grinding depth controlled at 0.1–0.15 mm.

[0036] The 60–80 mesh soft wire wheel has moderate hardness, effectively removing common mold release agents, oil stains, and aged layers from the surface of foamed outsoles, while avoiding excessive cutting or surface tearing caused by using coarse grinding wheels (such as those below 40 mesh), thus preventing localized strength reduction due to material damage. Combined with a rotation speed of 2800–3200 rpm, the grinding process is ensured to be smooth and uniform, forming a continuous and controllable rough texture, significantly increasing the specific surface area of ​​the bonding interface, which is beneficial for the full wetting and anchoring of subsequent treatment agents and adhesives. Unidirectional uniform grinding avoids stress intersections caused by cross-grinding, reducing the risk of microcrack initiation and improving overall interface consistency. More importantly, precisely controlling the grinding depth within the range of 0.1–0.15 mm exposes the fresh, unaged foamed substrate, improving chemical bonding, without weakening the structural strength of the overlapping area due to excessive grinding, thus affecting overall flexural resistance.

[0037] In some embodiments of this application, a treatment agent is applied to the roughened overlapping surface and allowed to dry, followed by the application of a water-based adhesive, specifically: Apply the treatment agent evenly to the roughened overlapping surface, apply two coats, and allow each coat to dry at room temperature for 5–10 minutes. Apply water-based polyurethane adhesive in two coats, allowing it to stand at room temperature for 10–15 minutes after each coat.

[0038] This step-by-step coating process, through precise parameter control, significantly improves the bonding reliability and durability between the foamed outsole and the intermediate rubber connecting piece. First, after roughening with a soft wire wheel, two coats of a treatment agent (such as a specially formulated halogenated or primer activator) thoroughly remove residual impurities. Simultaneously, the low surface energy foaming material (such as EVA and TPU) undergoes chemical polarity modification, enhancing its affinity and wettability with the adhesive, laying the foundation for a strong interfacial bond. Each coat is followed by 5–10 minutes of room temperature drying to ensure complete solvent evaporation and prevent the formation of a weak interfacial layer due to moisture or solvent residue. Subsequently, two coats of water-based polyurethane adhesive are applied. This water-based adhesive is environmentally friendly, non-toxic, flexible, and exhibits excellent resistance to damp heat aging and dynamic fatigue after curing. The two-coat application ensures uniform adhesive thickness and complete coverage, preventing localized debonding caused by missed areas or thin spots, while also avoiding defects such as sagging or bubbles caused by a single thick coat. After each coat of adhesive, allow it to stand for 10–15 minutes to allow the adhesive film to dry at room temperature, forming a continuous and dense adhesive layer. This facilitates optimal initial tack and final bond strength during subsequent bonding processes. This "double-coat, double-dry" process design not only improves process controllability and production consistency but also significantly enhances the stability of interfacial bonding through the multi-layer superposition effect.

[0039] In some embodiments of this application, the pressing pressure is 0.6–0.8 MPa, and the holding time is 30–60 seconds. These parameters are key process conditions to ensure a high-strength, highly consistent bond at the interface of the two-section outsole. After positioning and bonding the intermediate rubber connector to the front and rear foam outsoles, a dedicated pressing mold is used within this pressure and time range for pressing and shaping. This effectively promotes the full flow and wetting of the adhesive layer, allowing the water-based polyurethane adhesive to fully penetrate the roughened microporous structure of the foam outsole and the surface of the rubber connector, forming a strong and tough bonding interface with the synergy of mechanical anchoring and intermolecular forces. Controlling the pressing pressure between 0.6–0.8 MPa is sufficient to eliminate air and volatiles between the interfaces, eliminating bubbles and loose adhesion, while also preventing excessive pressure from causing over-compression of the foam material, decreased resilience, or displacement and deformation of the rubber connector. This ensures both a dense bond and maintains the original cushioning and flexibility of the outsole. The holding time is set to 30–60 seconds, which can achieve the initial cross-linking and curing of the adhesive under normal temperature or moderate heating conditions, ensuring that the bonded structure has sufficient initial strength after demolding and preventing misalignment or delamination caused by elastic rebound or external force disturbance.

[0040] A third aspect of this application provides a shoe including the two-section sole structure described in any of the first aspects above.

[0041] This shoe effectively solves the technical problems of fatigue cracking and structural breakage that traditional one-piece foam outsoles are prone to during long-term wear or repeated bending by employing a segmented high-performance outsole design. The two-section outsole structure uses lightweight, highly elastic foam material in the forefoot and heel areas for cushioning and weight reduction. Simultaneously, a 3 mm thick intermediate rubber connecting piece with a hardness of 40–45 Shore A is introduced in the metatarsophalangeal flex area, giving this area excellent flexibility and tear resistance. This allows the outsole to conform to the natural flexion of the foot during walking or exercise, significantly reducing localized stress concentration. A 35 mm overlap bonding surface, combined with surface treatment and water-based adhesive bonding technology, ensures a strong and durable interface between the forefoot and rear foam outsole and the rubber connecting piece. The 1.5 mm non-adhesive area reserved at the bonding edge further enhances edge peel resistance, preventing lifting or cracking caused by adhesive layer buildup. Actual wear testing showed that after two months of continuous wear, the sole of the shoe showed normal wear, and there was no glue separation or breakage at the joints, demonstrating excellent structural stability and durability.

[0042] For any parts not mentioned in this application, existing technologies may be used or referenced.

[0043] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0044] The above description is merely an embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A two-section shoe sole structure, characterized in that, include: A front section of foamed outsole, a rear section of foamed outsole, and an intermediate rubber connecting piece connecting the front section of foamed outsole and the rear section of foamed outsole; The front foam outsole and the rear foam outsole have overlapping surfaces in the overlapping area with the middle rubber connecting piece.

2. The two-section sole structure according to claim 1, characterized in that, The intermediate rubber connecting piece has a 1.5 mm non-adhesive area reserved at the edge of the bonding area with the front foam outsole and the rear foam outsole.

3. The two-section sole structure according to claim 1, characterized in that, The overlapping surfaces of the front and rear foam outsoles are coated with a treatment agent and a water-based adhesive.

4. The two-section sole structure according to claim 1, characterized in that, The intermediate rubber connecting piece has a hardness of 40 to 45 Shore A and a thickness of 3 mm.

5. The two-section sole structure according to claim 1, characterized in that, The overlap width of the overlapping surfaces is 35 mm.

6. A manufacturing process for a two-section shoe sole structure, used to manufacture the two-section shoe sole structure as described in any one of claims 1 to 5, characterized in that, include: The overlapping surfaces of the front and rear foam outsoles are roughened using a soft wire wheel. Apply a treatment agent to the roughened overlapping surfaces and let them dry, followed by the application of a water-based adhesive; After the water-based adhesive has been left to stand for 24 hours, the middle rubber connecting piece is bonded between the front foam outsole and the rear foam outsole, and a 1.5mm non-adhesive area is reserved at the bonding edge. Pressure is applied to the bonding area using a pressing mold and held to complete the pressing and shaping process.

7. The manufacturing process of the two-section shoe sole structure according to claim 6, characterized in that, The roughening treatment of the overlapping surface of the front and rear foam outsoles using a soft wire wheel specifically involves: Using a soft wire wheel with a grit size of 60–80 mesh, the overlapping surfaces are uniformly ground in one direction at a speed of 2800–3200 rpm, with the grinding depth controlled at 0.1–0.15 mm.

8. The manufacturing process of the two-section shoe sole structure according to claim 6, characterized in that, The process of applying a treatment agent to the roughened overlapping surface and allowing it to dry, followed by applying a water-based adhesive, specifically involves: Apply the treatment agent evenly to the roughened overlapping surface, apply two coats, and allow each coat to dry at room temperature for 5–10 minutes. Apply water-based polyurethane adhesive in two coats, allowing it to stand at room temperature for 10–15 minutes after each coat.

9. The manufacturing process of the two-section shoe sole structure according to claim 6, characterized in that, The pressing pressure is 0.6–0.8 MPa, and the holding time is 30–60 seconds.

10. A shoe, characterized in that, Includes the two-section sole structure as described in any one of claims 1 to 5.

Images