Casual shoes with microfiber leather surfaces

Abstract

The invention relates to the field of footwear products, and discloses a microfiber leather surface leisure shoe which comprises a vamp layer and a sole. The vamp layer is composed of a pretreated non-woven superfine fiber cloth base material and three functional coatings applied to the surface of the non-woven superfine fiber cloth base material; the three-layer functional coating comprises a bottom bonding layer, and the bottom bonding layer comprises the following components: polyether polyol, diisocyanate, a siloxane modifier, a chain extender, a neutralizer and deionized water; the middle functional layer is prepared from the following components: nano titanium dioxide and graphene oxide; the surface layer regulation and control layer comprises the following components: a transferable fluorine-containing terminal polyether; the vamp layer and the sole are bonded through a two-component hot-melt adhesive. Through gradient design of the three layers of functional coatings, bio-enzyme synergistic pretreatment and a silane end-capping bonding system, the interface bonding strength, antibacterial and anti-ultraviolet performance and durability of the microfiber leather vamp are remarkably improved, and integration of multiple functions is achieved.

Description

Technical Field

[0001] This invention relates to the field of footwear technology, and in particular to a casual shoe with a microfiber leather upper. Background Technology

[0002] Microfiber leather casual shoes hold an important position in the footwear industry due to their combination of the texture of natural leather and the designability of synthetic materials. However, traditional manufacturing processes face multiple challenges in terms of material performance and process adaptability: single-function coatings are insufficient to meet the comprehensive performance requirements of complex usage scenarios; substrate surface treatment methods present a contradiction between environmental impact and material damage; and the durability of bonding processes is limited by the interfacial bonding mechanism. These technical bottlenecks restrict further improvements in the comfort, functionality, and durability of microfiber leather footwear materials. To address these issues, technological breakthroughs are urgently needed through material system reconstruction, innovation in interfacial interaction mechanisms, and synergistic optimization of processes.

[0003] Currently, the industry generally uses a single-layer coating process to construct microfiber leather shoe uppers, achieving bonding between the substrate and the coating through physical adsorption. Substrate pretreatment often relies on strong acid and alkali chemical reagents to roughen the fiber surface, thereby improving coating adhesion. The coating curing process typically uses only a single thermosetting mode, relying on temperature-driven molecular chain movement to complete the cross-linking reaction. In the bonding stage between the shoe upper and the sole, traditional solutions mainly use ordinary EVA-based hot melt adhesives, forming an interfacial bond through physical cooling and setting.

[0004] While existing technologies have improved material properties to some extent through physical modification, several shortcomings remain. Single-layer coating structures, lacking functional gradient design, cannot achieve a balance between interfacial bonding strength, antibacterial and UV resistance, and dynamic hydrophobicity, resulting in limited material functionality and susceptibility to failure. Strong acid and alkali pretreatment, although increasing substrate surface roughness, can lead to excessive erosion of the fiber matrix, causing mechanical property degradation and presenting wastewater treatment challenges. Traditional thermosetting processes, lacking molecular-level cross-linking control mechanisms, struggle to build a synergistic network of physical entanglement and chemical cross-linking within the coating, making it difficult to achieve both material flexibility and aging resistance. Furthermore, the physical bonding mode of ordinary hot melt adhesives is prone to a sharp drop in strength due to interfacial hydrolysis in humid and hot environments, affecting product lifespan. Summary of the Invention

[0005] The purpose of this invention is to provide a microfiber leather casual shoe that solves the problems of existing microfiber leather casual shoes, such as limited coating functionality, insufficient interfacial bonding strength, damage to the substrate pretreatment, and poor durability of the adhesive layer.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a microfiber leather casual shoe, the casual shoe comprising an upper layer and a sole: The upper layer consists of a pretreated nonwoven microfiber fabric substrate and three functional coatings applied to its surface; the three functional coatings include: The bottom adhesive layer comprises the following components in parts by weight: polyether polyol: 45-55 parts, diisocyanate: 25-35 parts, siloxane modifier: 5-10 parts, chain extender: 5-10 parts, neutralizer: 1-3 parts, and deionized water: 150-250 parts. The bottom adhesive layer not only serves as an interface transition and bonding layer, but its core function lies in introducing siloxane-modified segments into the polyurethane network system generated by the reaction of polyether polyol and diisocyanate. This allows the adhesive layer to exhibit both high adhesion and excellent flexibility and hygrothermal stability. Furthermore, the simultaneous introduction of chain extender and neutralizer ensures that the emulsion system possesses highly controllable crosslinking density and molecular uniformity during formation, thereby guaranteeing the compatibility between subsequent coatings.

[0007] The intermediate functional layer comprises the following components in parts by weight: nano-titanium dioxide: 0.5-1.5 parts and graphene oxide: 0.1-0.5 parts; A composite system of nano-titanium dioxide and graphene oxide is used to introduce nanofillers with photoresponsiveness, thermal stability, and shielding functions into the material layer. This composite filler not only endows the coating with UV resistance and thermal resistance, but its disordered microstructure formed in a dispersed state also helps to improve the overall density of the coating, further shielding it from external particle erosion and moisture penetration, thereby improving the adaptability of the shoe upper material in the wearing environment.

[0008] The bottom adhesive layer decomposes organic matter through photocatalysis, while the middle functional layer constructs a physical barrier network with its two-dimensional sheet structure. The synergistic effect of the two forms a composite protection mechanism at the microscale.

[0009] Surface control layer, the surface control layer comprising the following components in parts by weight: 0.05-0.2 parts of migratory fluorinated terminal polyether; During the migration of fluorinated segments on the coating surface, they actively orient themselves toward the interface driven by the difference in surface energy, thereby forming a molecular arrangement structure with low surface energy and high hydrophobicity on the material surface.

[0010] The upper layer and the sole are bonded together by a two-component hot-melt adhesive, which is made of 50-70 parts modified polyester resin, 3-8 parts silane end-capping agent, and 30-60 parts diluent.

[0011] Preferably, the pretreatment uses a mixture prepared by mixing 1-3 parts cellulase, 0.5-2 parts lipase, and 100-200 parts deionized water.

[0012] Preferably, the three-layer functional coating is heat-treated at a temperature of 90-120°C.

[0013] This invention also provides a method for preparing a microfiber leather casual shoe, which includes the following steps: The nonwoven microfiber fabric substrate is pretreated by using a treatment solution containing cellulase and lipase, followed by rinsing and drying. Aqueous polyether-siloxane modified polyurethane emulsions were prepared by reacting polyether polyols with diisocyanates and adding siloxane modifiers, chain extenders and neutralizers during the reaction to form an emulsion suitable for coating. Functional additives are added to the emulsion to form a composite coating emulsion; The composite coating emulsion is sequentially applied to the surface of the base fabric and then dried appropriately. The coating is subjected to heat treatment and UV curing. The cured upper material is then heat-fused to the sole.

[0014] Preferably, the pretreatment step of the substrate includes: After the nonwoven microfiber fabric substrate is cut to the predetermined size, it is immersed in a treatment solution containing cellulase and lipase at a temperature of 40-55℃ for 10-30 minutes. Cellulase selectively hydrolyzes the ends of short fibers in nonwoven fabrics, exposing more active groups; lipase decomposes residual spinning oil on the fiber surface, forming a micron-scale rough surface. This dual bio-physical modification significantly increases the specific surface area and reactive sites of the substrate, providing an optimized interfacial environment for subsequent coating adhesion.

[0015] After processing, remove the substrate and rinse it with deionized water 2-3 times to remove residual enzyme solution. The substrate is then placed in an oven at 50-65℃ for drying for 10-20 minutes until it is completely dry.

[0016] Preferably, the preparation steps of the aqueous polyether-siloxane modified polyurethane emulsion include: Polyether polyol and diisocyanate are added to a reaction vessel, the temperature of which is controlled at 60-75℃, and the reaction is carried out at this temperature for 2-3 hours. After the reaction is complete, add siloxane modifier and chain extender, and continue the reaction for 1-2 hours; After the reaction is complete, add a neutralizing agent to adjust the pH of the emulsion to 6.5-7.5; Finally, the reactants are slowly emulsified with deionized water until a uniform aqueous polyurethane emulsion is formed, which is then ready for use.

[0017] Preferably, the step of adding the functional additive includes: Nano-titanium dioxide, graphene oxide, and fluorinated terminal polyethers are added to an aqueous polyurethane emulsion. The above-mentioned functional additives are slowly added to the emulsion and stirred continuously at 60-70℃ for 2-3 hours until the emulsion is fully homogeneous, ensuring that the functional additives are completely dissolved and evenly dispersed in the emulsion, thus obtaining a composite coating emulsion.

[0018] Preferably, the coating step of the composite coating emulsion includes: The composite coating emulsion is applied to the surface of the substrate in three layers using a roller coating machine. The base coat application rate is 30-50 g / m². 2 After coating, first dry in an oven at 50-70℃ for 5-10 minutes; the intermediate coating amount is 20-30g / m². 2 After coating, dry for 5-8 minutes under the same temperature conditions; The surface coating amount is 10-20 g / m². 2 After coating, dry at 50-70℃ for 5-8 minutes to ensure the coating is uniform and free of bubbles.

[0019] Before coating, nano-titanium dioxide, graphene oxide, and fluorinated terminal polyethers are added to the composite coating emulsion to ensure uniform distribution and enhance the coating's functionality. These coatings, through a multi-layered coating and drying process, progressively strengthen the adhesion and durability between layers. The thickness and curing conditions of each layer are strictly controlled to ensure a robust multi-layered structure is formed between the coatings without affecting the flexibility and comfort of the final product.

[0020] Preferably, the heat treatment and UV curing steps include: The coated and dried substrate is treated in a hot air oven at 90-120℃ for 5-10 minutes to promote initial curing of the coating; subsequently, the treated substrate is placed in an ultraviolet curing device for UV curing, using ultraviolet light with a wavelength of 355-375nm and a curing power of 80-120mW / cm². 2 The irradiation time should be controlled at 30-60 seconds to ensure that the coating is fully cured and forms a durable surface.

[0021] The thermosetting stage promotes the reorganization and movement of polyurethane chain segments, forming a physically entangled network; the UV curing stage establishes chemical crosslinking points through photo-initiated free radical reactions. This dual curing mechanism ensures the coating's flexibility while improving its aging resistance. The selective absorption of specific wavelengths of ultraviolet light ensures the effective activation of the initiator, while precise control of irradiation intensity avoids excessive crosslinking on the coating surface.

[0022] Preferably, the bonding step between the cured upper material and the sole includes: A hot-melt two-component adhesive is prepared, comprising modified polyester resin, silane end-capping agent, and diluent, and mixed evenly. Apply the adhesive evenly to the joint surface of the shoe upper and sole, with an application rate of 5-10 g / m². 2 ; The glued upper and sole are pressed together using a hot press. The hot pressing temperature is 120-150℃, the applied pressure is 0.5-1.5MPa, and the pressing time is 15-25 seconds. After pressing, the shoe body is cooled to room temperature to form a strong bond between the upper and the sole.

[0023] During hot pressing, the silane end-capping agent undergoes a desealing reaction with the polyester resin, releasing silanol groups that simultaneously form chemical bonds with the upper coating and sole material. The diluent's evaporation gradient design achieves a balance between the cohesive strength and interfacial bonding of the adhesive layer. Furthermore, the hot pressing temperature, pressure, and time regulate polymer chain movement, enabling the adhesive interface to form an interpenetrating network structure.

[0024] In summary, the present invention has at least one of the following beneficial technical effects: 1. Through the gradient distribution design of three functional coatings, multi-dimensional synergy of material properties is achieved. The bottom bonding layer significantly improves the interfacial bonding strength by chemically bonding the polyurethane modified with siloxane to the substrate; the middle functional layer utilizes the heterogeneous structure of nano-titanium dioxide and graphene oxide to construct a composite protective network, endowing the material with excellent antibacterial and UV-resistant properties; the surface regulating layer achieves a balance between hydrophobicity and breathability through the dynamic migration characteristics of fluorinated polyether, solving the technical defects of the single function of traditional microfiber leather footwear materials.

[0025] 2. A synergistic treatment process using cellulase and lipase was employed to construct a micron-nano composite structure on the surface of nonwoven microfiber fabric. This process selectively hydrolyzes fiber ends and removes surface oils, exposing more active groups and increasing the specific surface area, thus providing an optimized interfacial environment for subsequent coating adhesion. This biocatalytic modification method avoids the damage to the fiber matrix caused by traditional strong acid and alkali treatments, significantly improving the surface functionalization efficiency while ensuring the mechanical properties of the substrate.

[0026] 3. The synergistic effect of thermosetting and UV curing enables the controllable construction of the coating structure. During the thermosetting stage, a physically entangled network is formed through the movement and recombination of polyurethane segments, while the UV curing stage establishes chemical cross-linking points through photo-initiated free radical reactions. This staged energy input method ensures both the coating's flexibility and its aging resistance, while the selective absorption of ultraviolet light prevents excessive surface cross-linking, resulting in a stable structure with balanced internal and external properties.

[0027] 4. A silane-terminated polyester resin is used as the adhesive material. During hot pressing, a desealing reaction occurs, releasing silanol groups that form chemical bonds with the upper coating and sole material. This system controls the balance between the cohesive strength and interfacial bonding of the adhesive layer through a diluent evaporation gradient design, resulting in an interpenetrating network structure at the adhesive interface. This combined mechanism of chemical bonding and physical penetration significantly improves adhesive durability and solves the problem of rapid strength drop in traditional hot melt adhesives under humid and hot environments. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the preparation method of the present invention. Detailed Implementation

[0029] The following is in conjunction with the appendix Figure 1 The present invention will be further described in detail below.

[0030] Unless otherwise stated, the raw materials and reagents used in the following examples are commercially available products or can be prepared by known methods.

[0031] like Figure 1 As shown: Example 1: This invention provides a microfiber leather casual shoe, which includes an upper layer and a sole: The upper layer consists of a pre-treated non-woven microfiber fabric substrate and three functional coatings applied to its surface; The three-layer functional coating includes: Bottom adhesive layer: 50 parts polyether polyol, 30 parts diisocyanate, 7 parts siloxane modifier, 8 parts chain extender, 2 parts neutralizer, and 200 parts deionized water; Middle functional layer: 1.0 part of nano-titanium dioxide, 0.3 parts of graphene oxide; Surface control layer: 0.12 parts of fluorinated terminal polyether; The adhesive is made of 60 parts modified polyester resin, 5 parts silane end-capping agent, and 45 parts diluent.

[0032] The method for preparing the microfiber leather casual shoes includes: S1. Substrate Pretreatment: After cutting the nonwoven microfiber fabric, immerse it in a treatment solution containing a mixture of cellulase, lipase, and deionized water, and treat at 45°C for 20 minutes. After removal, rinse 3 times and dry at 60°C for 15 minutes.

[0033] S2. Preparation of polyurethane emulsion: Polyether polyol and diisocyanate are reacted at 68°C for 2.5 hours, followed by the addition of siloxane modifier and chain extender, and the reaction continues for another 1.5 hours. A neutralizing agent is added until the pH reaches 7.0, and then the mixture is emulsified to obtain the emulsion.

[0034] S3. Preparation of functional layer: Add nano-TiO2, graphene oxide and fluorinated polyether to the emulsion, stir at 65°C for 2.5 hours to obtain coating emulsion.

[0035] S4. Coating Application: Using a roller coating machine, the composite coating emulsion is applied to the surface of the substrate in three layers, with the bottom layer at 40g / m². 2 (Dry at 60℃ for 8 minutes), middle layer 25g / m 2 (Dry at 60℃ for 6 minutes), surface layer 15g / m 2 (Dry at 60℃ for 6 minutes).

[0036] S5. Curing treatment: Curing with hot air at 105℃ for 8 minutes, followed by 365nm UV light (100mW / cm²). 2 Irradiate for 45 seconds.

[0037] S6. Shoe sole bonding: Adhesive application rate 8g / m 2 Press at 135℃ (1.0MPa) for 20 seconds, then allow to cool and set naturally.

[0038] Example 2: The three-layer functional coating includes: Bottom adhesive layer: 45 parts polyether polyol, 25 parts diisocyanate, 5 parts siloxane modifier, 5 parts chain extender, 1 part neutralizer, and 150 parts deionized water. Middle functional layer: 0.5 parts nano-titanium dioxide, 0.1 parts graphene oxide; Surface control layer: 0.05 parts of fluorinated terminal polyether; The adhesive is made of 50 parts modified polyester resin, 3 parts silane end-capping agent, and 30 parts diluent.

[0039] The method for preparing the microfiber leather casual shoes includes: S1. Substrate Pretreatment: After cutting the nonwoven microfiber fabric, immerse it in a treatment solution containing a mixture of cellulase, lipase, and deionized water, and treat at 40°C for 30 minutes. Rinse twice and then dry at 50°C for 20 minutes.

[0040] S2. Preparation of polyurethane emulsion: 45 parts of polyether polyol and 25 parts of diisocyanate were reacted at 60°C for 3 hours. 5 parts of siloxane modifier and 5 parts of chain extender were added, and the reaction continued for 2 hours. A neutralizing agent was added until the pH reached 6.5, and then emulsified to obtain the emulsion.

[0041] S3. Preparation of functional layer: Add nano TiO2, 0.1 parts graphene oxide and 0.05 parts fluorinated polyether, stir at 60°C for 3 hours to obtain coating emulsion.

[0042] S4. Coating Application: Using a roller coating machine, the composite coating emulsion is applied to the surface of the substrate in three layers, with the bottom layer at 30g / m². 2 (Dry at 50℃ for 10 minutes), middle layer 20g / m 2 (Dry at 50℃ for 8 minutes), surface layer 10g / m 2 (Dry at 50℃ for 8 minutes).

[0043] S5. Curing treatment: After treatment at 90℃ for 10 minutes, apply 355nm UV light (80mW / cm²). 2 Irradiate for 60 seconds.

[0044] S6. Sole bonding: Adhesive application rate 5g / m 2 Hot-pressed at 120℃ (0.5MPa) for 25 seconds and then cooled.

[0045] Example 3: The three-layer functional coating includes: Bottom adhesive layer: 55 parts polyether polyol, 35 parts diisocyanate, 10 parts siloxane modifier, 10 parts chain extender, 3 parts neutralizer, and 250 parts deionized water. Middle functional layer: 1.5 parts nano-titanium dioxide, 0.5 parts graphene oxide; Surface control layer: 0.2 parts of fluorinated terminal polyether; The adhesive is made of 70 parts modified polyester resin, 8 parts silane end-capping agent, and 60 parts diluent.

[0046] The method for preparing the microfiber leather casual shoes includes: S1. Substrate Pretreatment: After cutting the nonwoven microfiber fabric, immerse it in a treatment solution containing a mixture of cellulase, lipase, and deionized water, and treat at 55°C for 10 minutes. Rinse 3 times and then dry at 65°C for 10 minutes.

[0047] S2. Preparation of polyurethane emulsion: 55 parts of polyether polyol and 35 parts of diisocyanate were reacted at 75°C for 2 hours. Then, 10 parts of siloxane modifier and 10 parts of chain extender were added, and the reaction was continued for 1 hour. After adding a neutralizing agent until the pH reached 7.5, the mixture was emulsified to obtain the emulsion.

[0048] S3. Preparation of functional layer: Add nano TiO2, 0.5 parts graphene oxide and 0.2 parts fluorinated polyether, stir at 70°C for 2 hours to obtain coating emulsion.

[0049] S4. Coating Application: Using a roller coating machine, the composite coating emulsion is applied to the surface of the substrate in three layers, with the bottom layer at 50g / m². 2 (Dry at 70℃ for 5 minutes), middle layer 30g / m 2 (Dry at 70℃ for 5 minutes), surface layer 20g / m 2 (Dry at 70℃ for 5 minutes).

[0050] S5. Curing treatment: After treatment at 120℃ for 5 minutes, apply 375nm UV light (120mW / cm²). 2 Irradiate for 30 seconds.

[0051] S6. Shoe sole bonding: Adhesive application rate 10g / m 2 Hot-pressed at 150℃ (1.5MPa) for 15 seconds, then cooled and shaped.

[0052] Comparative Example 1: Compared with Example 1, the difference is that no siloxane modifier was added to the bottom adhesive layer, while the other components and process parameters are the same.

[0053] Comparative Example 2: Compared with Example 1, the difference is that the enzyme treatment is omitted in the pretreatment step, and pure water soaking is used directly. All other process parameters are the same.

[0054] Comparative Example 3: Compared with Example 1, the difference is that the curing process only uses heat curing (105°C for 15 minutes), the UV curing step is omitted, and the other process parameters are the same.

[0055] Comparative Example 4: Compared with Example 1, the difference is that only 1.3 parts of nano-titanium dioxide were added to the middle functional layer, and no graphene oxide was added. The other components and process parameters are the same.

[0056] Comparative Example 5: Compared with Example 1, the difference is that the adhesive used is ordinary EVA hot melt adhesive (without silane end-capping agent), while the other components and process parameters are the same.

[0057] Comparative Example 6: Compared with Example 1, the difference is that the three-layer coating is replaced with a single-layer coating, while the other components and process parameters are the same.

[0058] Comparative Example 7: Compared with Example 1, the difference is that the amount of siloxane modifier added during the synthesis of polyurethane emulsion is increased to 15 parts, while the other components and process parameters are the same.

[0059] Comparative Example 8: Compared with Example 1, the difference is that heating and stirring were not performed during the functional additive addition stage, while the other process parameters are the same.

[0060] Comparative Example 9: Compared with Example 1, the difference is that the amount of fluorinated polyether added to the surface control layer is increased to 0.3 parts, while the other components and process parameters are the same.

[0061] Test Example 1: Experimental steps: Coating peel strength test: Sample preparation: Take the shoe upper material of Example 1 and Comparative Examples 1 / 4 / 6 / 7 / 9 and cut it into 25mm×150mm test pieces; Test conditions: tensile testing machine speed 100mm / min, clamp spacing 50mm; Bonding method: Use 3M double-sided tape to bond the coated surface to the stainless steel plate (contact pressure 0.2MPa, hold for 30s); Data acquisition: Record the average value of the stable peel force segment (50-100mm stroke).

[0062] Yellowing resistance test: Equipment parameters: UV aging chamber; Test cycle: 48 hours of continuous irradiation, with a break every 12 hours for observation; Rating method: Use a grayscale card to compare the initial sample and the aged sample, and record the ΔE color difference value; Dynamic waterproofing test: Testing apparatus: Water pressure tester (pressurization rate 6 kPa / min); Endpoint determination: Observe the pressure value when the third water droplet appears on the back of the coating; Pretreatment: The sample was pre-soaked in distilled water at 23℃ for 5 minutes. The experimental results are shown in Table 1.

[0063] Table 1. Comparison Test Data of Coating System Performance From Table 1, we can obtain: Experimental data show that when the siloxane modifier is missing (Comparative Example 1), the peel strength drops sharply, which verifies the crucial role of the chemical bonding mechanism between the siloxane groups and the hydroxyl groups on the fiber surface in interfacial bonding. The significant deterioration of the water pressure resistance of the single-layer coated sample (Comparative Example 6) confirms that the synergistic protection mechanism of the bottom highly cross-linked structure, the middle physical barrier network, and the surface dynamic hydrophobic layer is indispensable.

[0064] The absence of graphene oxide (Comparative Example 4) resulted in a 19% decrease in water pressure resistance, which is directly related to the tortuous barrier effect formed by its two-dimensional sheet structure. Although excessive fluorinated polyether (Comparative Example 9) temporarily improved yellowing resistance, it disrupted the surface energy balance, and subsequent tests showed that its antifouling performance deteriorated, confirming the critical control requirements for the migration rate of fluorinated segments.

[0065] Excessive addition of siloxane (Comparative Example 7) triggered phase separation, leading to localized defects in the coating. This is closely related to the optimal grafting efficiency of the siloxane modifier during the prepolymerization stage. Simultaneously, precise control of the undercoat amount in the gradient coating process (40 g / m² in Example 1) is crucial. 2 This ensures the effective construction of the stress buffer layer between coatings, avoiding the stress concentration problem caused by single-layer thick coating.

[0066] Test Example 2: Experimental steps: Sample preparation: Take samples from Example 1 and Comparative Examples 2, 3, and 8; Substrate water absorption test: Sample preparation: Cut the substrates of each control group into 100mm×100mm squares and bake at 105℃ to constant weight; Test method: Immerse in 23℃ distilled water for 30 minutes, remove and drain the surface water, then weigh immediately; Calculation formula: Water absorption rate (%) = [(wet weight - dry weight) / dry weight] × 100; Coating curing time measurement: Testing tool: Curing time meter (indentation method); Judgment criteria: The time point at which the needle indentation completely springs back without leaving any residue; Test conditions: Indenter load 500g, ambient temperature 23±1℃.

[0067] Analysis of failure modes at the adhesive interface: Sample preparation: After the bonded sample is frozen and brittle, it is treated with gold spraying. Observation method: Statistical analysis of the percentage of the three types of damage: Cohesive failure (internal fracture of the coating); Interface damage (coating-substrate separation); Mixed destruction, experimental results are shown in Table 2; Table 2 Validation data of preparation process parameters From Table 2, we can obtain: Comparative Example 2 shows a significant increase in water absorption of the untreated substrate. This is attributed to the selective hydrolysis of amorphous regions on the fiber surface by cellulase, exposing more hydroxyl active sites. Simultaneously, lipase decomposes residual lipids. The synergistic effect of these two processes forms a uniform micron-nano composite structure on the substrate surface, providing an ideal interface for subsequent coating wetting. The synergistic effect of the dual-curing process is fully demonstrated in Comparative Example 3. Single thermosetting results in an incomplete cross-linking network, while UV-induced free radical reactions effectively replenish the chemical bonds between molecular chains. This energy gradient application method gives the coating both flexibility and creep resistance.

[0068] The room-temperature stirring in Comparative Example 8 led to nanoparticle aggregation, which is closely related to the change in its zeta potential within the polyurethane emulsion. The 65°C stirring process, by increasing the system's kinetic energy, enabled the graphene oxide sheets to overcome van der Waals forces and fully exfoliate. Simultaneously, the migration rate of the fluorinated polyether reached a dynamic equilibrium with the stirring shear force, ensuring a gradient distribution of functional components in the coating. This temperature-shear synergistic mechanism is essential for obtaining a stable functional coating.

[0069] Test Example 3: Experimental steps: Sample preparation: Take three sets of bonding samples from Example 1 and Comparative Example 5, cut them into standard samples of 25mm × 100mm, and label them as A (soaked in distilled water), B (acidic solution of pH=3), and C (alkaline solution of pH=11), respectively.

[0070] Chemical treatment: Immerse each group of samples in the corresponding solution and soak at room temperature (23±2℃) for 24 hours; After soaking, remove the sample, blot the surface liquid with filter paper, and immediately perform a peel test.

[0071] Peel strength test: Use a tensile testing machine (range 50N, accuracy 0.1N), clamp spacing 50mm, tensile speed 50mm / min; Record the maximum force (N) when the sample is completely peeled off, and calculate the residual strength ratio (% = post-treatment strength / initial strength × 100).

[0072] Duplicate Validation: Five parallel samples were tested in each group, and the average value was taken as the final result. The experiment was repeated three times to verify the stability of the data. The experimental results are shown in Table 3.

[0073] Table 3 Results of Chemical Resistance Tests for Adhesion From Table 3, we can obtain: By comparing the adhesive performance differences between Example 1 and Comparative Example 5 in different chemical environments, it can be inferred that the silane end-capping agent plays a dual role at the interface: on the one hand, the silanol groups generated by its hydrolysis form stable covalent bonds with the metal oxides or hydroxyl groups on the surface of the shoe sole material; on the other hand, a transition layer is constructed through the gradient distribution of molecular chain segments. This combined mechanism of chemical bonding and physical entanglement allows Example 1 to maintain high adhesive strength in acidic or alkaline media, while the ordinary hot melt adhesive of Comparative Example 5, which relies solely on physical adsorption, experiences rapid interface failure due to environmental erosion.

[0074] Under heating and pressurization, the desealing reaction of the silane end-capping agent and the volatilization process of the diluent reach a dynamic equilibrium. This energy gradient regulation promotes the full movement and reorientation of polymer chain segments. In the experimental data, the residual strength ratio of Example 1 is significantly higher than that of Comparative Example 5, confirming the molecular-level reconstruction process of the adhesive interface: the directional migration of silane groups not only enhances the chemical bonding with the substrate, but also alleviates stress concentration through the interpenetrating network structure between molecular chains.

[0075] The structural characteristics of the three-layer coating determine the surface energy gradient and mechanical response of the upper material, and the introduction of the silane end-capping agent enables the adhesive layer to adapt to this gradient change. The differences in peel strength data observed in the experiment indicate that when the adhesive and coating system work synergistically, the stress transfer efficiency at the interface is significantly improved.

[0076] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A casual shoe with a microfiber leather upper, characterized in that, The casual shoe includes an upper and a sole: The upper layer consists of a pretreated nonwoven microfiber fabric substrate and three functional coatings applied to its surface. The three-layer functional coating includes: The bottom adhesive layer comprises the following components in parts by weight: polyether polyol: 45-55 parts, diisocyanate: 25-35 parts, siloxane modifier: 5-10 parts, chain extender: 5-10 parts, neutralizer: 1-3 parts, and deionized water: 150-250 parts. The intermediate functional layer comprises the following components in parts by weight: nano-titanium dioxide: 0.5-1.5 parts and graphene oxide: 0.1-0.5 parts; Surface control layer, the surface control layer comprising the following components in parts by weight: 0.05-0.2 parts of migratory fluorinated terminal polyether; The upper layer and the sole are bonded together by a two-component hot-melt adhesive, which is made of 50-70 parts modified polyester resin, 3-8 parts silane end-capping agent, and 30-60 parts diluent.

2. The microfiber leather casual shoe according to claim 1, characterized in that, The pretreatment uses a mixture made of 1-3 parts cellulase, 0.5-2 parts lipase, and 100-200 parts deionized water.

3. A casual shoe with microfiber leather upper according to claim 1, characterized in that, The three-layer functional coating is heat-treated at a temperature of 90-120℃.

4. A method for preparing a casual shoe with microfiber leather upper, characterized in that, The preparation of a microfiber leather casual shoe according to any one of claims 1-3 includes the following steps: The nonwoven microfiber fabric substrate is pretreated by using a treatment solution containing cellulase and lipase, followed by rinsing and drying. Aqueous polyether-siloxane modified polyurethane emulsions were prepared by reacting polyether polyols with diisocyanates and adding siloxane modifiers, chain extenders and neutralizers during the reaction to form an emulsion suitable for coating. Functional additives are added to the emulsion to form a composite coating emulsion; The composite coating emulsion is sequentially applied to the surface of the base fabric and then dried appropriately. The coating is subjected to heat treatment and UV curing. The cured upper material is then heat-fused to the sole.

5. The method for preparing a microfiber leather casual shoe according to claim 4, characterized in that, The pretreatment steps for the substrate include: After the nonwoven microfiber fabric substrate is cut to the predetermined size, it is immersed in a treatment solution containing cellulase and lipase at a temperature of 40-55℃ for 10-30 minutes. After processing, remove the substrate and rinse it with deionized water 2-3 times to remove residual enzyme solution. The substrate is then placed in an oven at 50-65℃ for drying for 10-20 minutes until it is completely dry.

6. The method for preparing a microfiber leather casual shoe according to claim 4, characterized in that, The preparation steps of the aqueous polyether-siloxane modified polyurethane emulsion include: Polyether polyol and diisocyanate are added to a reaction vessel, the temperature of which is controlled at 60-75℃, and the reaction is carried out at this temperature for 2-3 hours. After the reaction is complete, add siloxane modifier and chain extender, and continue the reaction for 1-2 hours; After the reaction is complete, add a neutralizing agent to adjust the pH of the emulsion to 6.5-7.5; Finally, the reactants are slowly emulsified with deionized water until a uniform aqueous polyurethane emulsion is formed.

7. The method for preparing a microfiber leather casual shoe according to claim 4, characterized in that, The step of adding the functional additive includes: Nano-titanium dioxide, graphene oxide, and fluorinated terminal polyethers are added to an aqueous polyurethane emulsion. The above-mentioned functional additives are slowly added to the emulsion and stirred continuously at 60-70℃ for 2-3 hours until the emulsion is fully homogeneous, ensuring that the functional additives are completely dissolved and evenly dispersed in the emulsion, thus obtaining a composite coating emulsion.

8. The method for preparing a microfiber leather casual shoe according to claim 4, characterized in that, The coating process of the composite coating emulsion includes: The composite coating emulsion is applied to the surface of the substrate in three layers using a roller coating machine. The base coat application rate is 30-50 g / m². 2 After coating, first dry in an oven at 50-70℃ for 5-10 minutes; The intermediate coating amount is 20-30 g / m² 2 After coating, dry for 5-8 minutes under the same temperature conditions; The surface coating amount is 10-20 g / m². 2 After coating, dry at 50-70℃ for 5-8 minutes to ensure the coating is uniform and free of bubbles.

9. The method for preparing a microfiber leather casual shoe according to claim 4, characterized in that, The heat treatment and UV curing steps include: Treat the coated and dried substrate in a hot air oven at 90-120℃ for 5-10 minutes to promote the initial curing of the coating. Subsequently, the treated substrate is placed in an ultraviolet curing device for UV curing, using ultraviolet light with a wavelength of 355-375nm and a curing power of 80-120mW / cm². 2 The irradiation time should be controlled at 30-60 seconds to ensure that the coating is fully cured and forms a durable surface.

10. The method for preparing a microfiber leather casual shoe according to claim 4, characterized in that, The bonding steps between the cured upper material and the sole include: A hot-melt two-component adhesive is prepared, comprising modified polyester resin, silane end-capping agent, and diluent, and mixed evenly. Apply the adhesive evenly to the joint surface of the shoe upper and sole, with an application rate of 5-10 g / m². 2 ; The glued upper and sole are pressed together using a hot press. The hot pressing temperature is 120-150℃, the applied pressure is 0.5-1.5MPa, and the pressing time is 15-25 seconds. After pressing, the shoe body is cooled to room temperature to form a strong bond between the upper and the sole.

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