Upper-pulling waterproof and cold-proof shoe and manufacturing method thereof

Abstract

The invention relates to the technical field of shoe manufacturing, in particular to upper-pulling waterproof and cold-proof shoes and a manufacturing method thereof. A curing adhesive layer of the shoe is formed by pressing and post-curing a special adhesive film, and the adhesive film is prepared from polytetramethylene ether glycol, isophorone diisocyanate, nano silicon dioxide with the surface grafted with glycidyl carbamate groups, glycidol and a 2-methylimidazole latent microcapsule coated with polycaprolactone. The key point of the method is that the modified nano material and the latent microcapsule are prepared step by step, and a two-stage process of firstly pre-pressing at low temperature to enable an adhesive film to fully wet a base material and then carrying out high-temperature final pressing to trigger curing is adopted. According to the method, the low-temperature flexibility, the bonding stability and the long-acting waterproof performance of the upper-sole bonding interface can be synergistically improved.

Description

Technical Field

[0001] This invention relates to the field of footwear manufacturing technology, and in particular to a waterproof and cold-weather shoe with uppers and its manufacturing method. Background Technology

[0002] In the manufacturing of zip-up shoes, the bonding quality at the joint between the upper and sole directly determines the shoe's waterproofness, durability, and wearing comfort. To improve the performance of this crucial component, the industry has explored various technological approaches, but each has its own limitations.

[0003] Hot melt adhesives are widely used due to their ease of use and rapid curing, but their adhesive layers generally suffer from reduced flexibility in low-temperature environments. Under cold conditions, the hot melt adhesive layer tends to harden and become brittle, making it difficult to adapt to the repeated bending and deformation of the shoe body during walking. This leads to the initiation and gradual expansion of microcracks at the interface, eventually causing the adhesive to come unglued or leaking, failing to meet the stringent requirements for low-temperature flexibility in cold-weather shoes.

[0004] Using conventional polyurethane adhesives is another common solution, offering superior flexibility compared to hot melt adhesives. However, improving initial peel strength often requires increasing the proportion of hard segments or crosslinking density in the system, which sacrifices the material's inherent flexibility and increases the risk of embrittlement. More importantly, during the curing process of conventional polyurethane adhesives, the reaction occurs simultaneously with interface wetting and bonding, easily creating pre-cured voids at the microscopic unevenness of the upper-sole bonding surface due to curing shrinkage. These microscopic defects become preferential channels for moisture penetration in humid environments, severely weakening the shoe's static and dynamic waterproofing capabilities.

[0005] In addition, some technologies have attempted to add inorganic fillers (such as nano-silica) to adhesives to enhance mechanical properties and barrier properties. However, if nanoparticles are used as ordinary fillers in physical blending, their interfacial compatibility with the polymer matrix is ​​poor, and they are prone to agglomeration. Not only do they fail to form an effective water barrier, but they may also introduce stress concentration points at the interface, accelerating failure under bending stress. At the same time, latent curing agents introduced to improve storage stability or control curing speed may cause premature curing reactions if their activation mechanisms are not compatible with the interface formation process. This will also hinder the adhesive from fully wetting and flowing to the substrate, failing to form a dense and seamless bonding interface.

[0006] In summary, existing technologies often compromise on certain aspects when dealing with the combined harsh conditions of low temperature, humidity, and dynamic bending: pursuing high initial bond strength may lead to a decrease in flexibility and crack resistance; emphasizing barrier properties may sacrifice interfacial bonding strength; and improving processability may affect the density and integrity of the final interface. Therefore, developing a new method that can synergistically resolve the contradictions between low-temperature flexibility, interfacial bond stability, and long-term waterproofing has become a pressing technical challenge in this field. Summary of the Invention

[0007] In view of this, the purpose of this invention is to propose a waterproof and cold-proof shoe with upper and its manufacturing method, so as to solve the technical problem that existing shoe bonding technology is difficult to achieve high flexibility, high bonding strength and high density and waterproofness at the interface of upper and sole under the combined effects of low temperature, humidity and repeated bending, and is prone to micro-voids at the interface due to pre-curing.

[0008] To achieve the above objectives, the present invention provides a waterproof and cold-weather shoe with uppers, a sole, and a cured adhesive layer located between the upper part of the shoe and the adhesive part of the sole. The cured adhesive layer is formed by pressing and post-curing an adhesive film for waterproof and cold-weather shoes.

[0009] Furthermore, the waterproof and cold-proof shoe film is prepared from the following raw materials: 250-560 parts of polytetramethylene ether glycol with a number average molecular weight of 3000-6000, 40-55 parts of isophorone diisocyanate, 2-4 parts of nano-silica with surface grafted glycidyl urethane groups, 12-18 parts of glycidyl urethane and 7-11 parts of polycaprolactone-coated 2-methylimidazole latent microcapsules; Furthermore, the surface-grafted glycidyl urethane-based nano-silica is obtained by modifying nano-silica with 3-isocyanate propyltriethoxysilane, followed by reaction with glycidyl urethane in the presence of dibutyltin dilaurate; the amounts of nano-silica, 3-isocyanate propyltriethoxysilane, glycidyl urethane, and dibutyltin dilaurate, by mass, are 8-12:1.5-2.5:0.8-1.2:0.04-0.06.

[0010] Furthermore, the polycaprolactone-coated 2-methylimidazole latent microcapsules are prepared by emulsification of 2-methylimidazole with polycaprolactone and polyvinyl alcohol as a dispersant and stabilizer; the amount of polycaprolactone, 2-methylimidazole and polyvinyl alcohol is 8-12:4-6:2.5-3.5 by mass.

[0011] Preferably, the thickness of the adhesive film is 0.15-0.25 mm.

[0012] Preferably, the upper is a polyester woven fabric composite polyurethane synthetic leather upper, and the sole is an EVA / rubber composite cold-proof sole.

[0013] Furthermore, the present invention also provides a waterproof and cold-weather shoe with uppers and a method for manufacturing the same, comprising the following steps: (1) Preparation of nano-silica with glycidyl urethane groups grafted on the surface; (2) Reaction of polytetramethylene ether diol with isophorone diisocyanate, and addition of nano-silica with glycidyl urethane groups grafted on the surface obtained in step (1) to disperse the reaction, to obtain isocyanate-terminated polyurethane prepolymer containing nano-rigid phase. (3) Glycidyl ether is added to the isocyanate-terminated polyurethane prepolymer obtained in step (2) to react and obtain the epoxy-terminated polyurethane prepolymer. (4) Preparation of polycaprolactone-coated 2-methylimidazole latent microcapsules; (5) The epoxy polyurethane prepolymer obtained in step (3) is mixed with the polycaprolactone-coated 2-methylimidazole latent microcapsules obtained in step (4), degassed, and made into a film. (6) Place the adhesive film obtained in step (5) between the upper part of the shoe upper blank and the bonding part of the sole blank. After positioning according to the lasting process, first pre-press at 50-60℃ and 0.15-0.25MPa for 25-35s, then final press at 88-92℃ and 0.6-0.8MPa for 65-75s, followed by pressure holding and cooling for 15-25s. After pressing, cure at 55-65℃ for 3-5h, and then place at room temperature for 24h to obtain the lasted waterproof and cold-proof shoes.

[0014] Preferably, in step (6), the upper part of the shoe blank and the bonding part of the sole blank are lightly sanded to a glossy surface with 180-220 grit sandpaper, wiped with anhydrous ethanol after dust removal, and baked at 45-55℃ for 2-4 minutes.

[0015] Preferably, in step (4), by mass, 8-12 parts of polycaprolactone are dissolved in 70-90 parts of dichloromethane as the oil phase, and 4-6 parts of 2-methylimidazole are dissolved in 8-12 parts of deionized water as the inner aqueous phase. The inner aqueous phase is added to the oil phase and emulsified at 2800-3200 r / min for 4-6 min to form a primary emulsion. Separately, 2.5-3.5 parts of polyvinyl alcohol are dissolved in 295-299 parts of deionized water to prepare an outer aqueous phase. The primary emulsion is added to the outer aqueous phase at 35-39°C and stirred at 750-850 r / min for 2.5-3.5 h. The mixture is then filtered, washed, and vacuum dried at 33-37°C for 10-12 h to obtain polycaprolactone-coated 2-methylimidazole latent microcapsules.

[0016] The beneficial effects of this invention are: Significantly improved low-temperature flexibility and fatigue resistance of the upper-sole bonding interface: By using polyether diols with a specific molecular weight range to construct the polyurethane backbone and using glycidyl ether to precisely position the reactive epoxy groups at the ends of the polyurethane chain, the resulting adhesive system maintains the good mobility of the polymer chain at low temperatures without significantly increasing the overall hard segment ratio, and provides clear and efficient active sites for subsequent curing reactions. This ensures that the bonding interface can still maintain good deformation recovery and crack resistance when the shoe body is repeatedly bent in cold environments.

[0017] Effectively enhances interfacial adhesion stability and water-blocking durability: By introducing nano-silica with a surface progressively modified surface of isocyanate propyltriethoxysilane and glycidyl ether during the polyurethane prepolymer stage, it enables preferential polar association and anchoring with the hard segment micro-regions in the prepolymer via the urethane groups on its surface. This pre-anchoring method allows nanoparticles to be stably dispersed in the hard segment neighborhood, not only acting as physical reinforcement points to improve peel strength, but also constructing tortuous nanoscale barrier paths at the interface, effectively delaying the diffusion and penetration of moisture along the interface, and improving the long-term durability of the adhesive joint in humid environments.

[0018] The timing of interface forming and curing reactions was optimized, ensuring the density and integrity of the interface: 2-methylimidazole was coated with polycaprolactone to form latent curing microcapsules, which were then mixed after the formation of an end-epoxy polyurethane prepolymer. Combined with a specific two-stage pressing process (low-temperature pre-pressing followed by high-temperature final pressing), the adhesive film can be fully softened, flowed, and wetted at a lower temperature, expelling internal air and achieving initial interface shaping and tight adhesion. Subsequently, the high temperature of the final pressing triggers the release of the curing agent from the microcapsules, initiating a cross-linking reaction of the epoxy groups. This mechanism of first wetting and bonding, then triggering curing, effectively avoids adhesive layer embrittlement and the formation of interfacial microvoids caused by premature curing, thereby significantly improving the static waterproof sealing and dynamic waterproof reliability of the upper-sole joint. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0020] Raw material sources and types: Polytetramethylene ether glycol uses PTMEG series polyether diols, with Example 1 using a number-average molecular weight of 4000, Example 2 using a number-average molecular weight of 3000, Example 3 using a number-average molecular weight of 5000, Example 4 using a number-average molecular weight of 6000, and Example 5 using a number-average molecular weight of 4500; Nano silica uses AEROSIL 200; Polycaprolactone uses CAPA 6800; Polyvinyl alcohol uses KURARAY POVAL PVA-205; Polyester release film uses a 50μm thick silicone oil release polyester film; Upper blank uses polyester woven fabric composite polyurethane synthetic leather upper blank; Sole blank uses EVA / rubber composite cold-proof sole blank.

[0021] Example 1: Step 1: 10g of nano-silica was vacuum dried at 120℃ for 2h, then added to 120g of anhydrous toluene and ultrasonically dispersed for 10min. Under nitrogen protection, 2g of 3-isocyanate propyltriethoxysilane was added, and the mixture was stirred at 70℃ for 3h. After filtration, the mixture was washed twice with 30g of anhydrous toluene and vacuum dried at 60℃ for 2h to obtain nano-silica with isocyanate groups on the surface. The obtained powder was then dispersed in 80g of anhydrous ethyl acetate, and 1g of glycidyl ether and 0.05g of dibutyltin dilaurate were added dropwise at 30-35℃. The reaction was continued for 4h, and after filtration, the mixture was washed twice with anhydrous ethyl acetate and vacuum dried at 40℃ for 4h to obtain nano-silica with glycidyl urethane groups grafted on the surface. Step 2: Place 420g of polytetramethylene ether glycol in a conventional reactor equipped with a stirrer, thermometer, and nitrogen gas introduction. Dehydrate at 110℃ under vacuum for 2 hours, then lower the temperature to 80℃ and introduce dry nitrogen gas. Add 45g of isophorone diisocyanate and maintain the reaction at 80℃ for 3 hours. Then add 3g of nano-silica with glycidyl urethane groups grafted on the surface and continue to disperse and react at 75℃ for 1 hour to obtain an isocyanate-terminated polyurethane prepolymer containing a nano-rigid phase. Step 3: Cool the prepolymer obtained in Step 2 to 58°C, add 15g glycidyl ether dropwise over 30 min, then maintain the reaction at 58°C for 3 h, remove trace amounts of volatiles under reduced pressure, and cool to 40°C to obtain the end-epoxy polyurethane prepolymer. Step 4: Dissolve 10g of polycaprolactone in 80g of dichloromethane as the oil phase, and dissolve 5g of 2-methylimidazole in 10g of deionized water as the inner aqueous phase; slowly add the inner aqueous phase to the oil phase and emulsify at 3000r / min for 5min to form a primary emulsion; separately dissolve 3g of polyvinyl alcohol in 297g of deionized water to prepare the outer aqueous phase, and slowly add the primary emulsion to the outer aqueous phase at 37℃ and stir at 800r / min for 3h; filter, wash twice with deionized water, and vacuum dry at 35℃ for 12h to obtain polycaprolactone-coated 2-methylimidazole latent microcapsules; Step 5: Stir the epoxy polyurethane prepolymer obtained in Step 3 at 45°C, add 9g of polycaprolactone-coated 2-methylimidazole latent microcapsules, mix for 15min, vacuum degas for 10min, then coat it onto a polyester release film at 45°C and flatten it with a cold roller to form a film with a thickness of 0.2mm. Step 6: Lightly sand the upper part and the bonding part of the sole blank with 180-grit sandpaper until they are glossy. After dust removal, wipe with anhydrous ethanol and bake at 50℃ for 3 minutes. Place the adhesive film obtained in Step 5 into the bonding area between the upper and sole. After positioning according to the conventional lasting process, pre-press at 55℃ and 0.2MPa for 30 seconds, then final press at 90℃ and 0.7MPa for 70 seconds, followed by holding the pressure and cooling for 20 seconds. After pressing, cure at 60℃ for 4 hours and then place at room temperature for 24 hours to obtain the lasted waterproof and cold-proof shoe.

[0022] Example 2: Step 1: 8g of nano-silica was vacuum dried at 115℃ for 1.5h, added to 100g of anhydrous toluene and ultrasonically dispersed for 8min. Under nitrogen protection, 1.5g of 3-isocyanate propyltriethoxysilane was added, and the mixture was stirred at 65℃ for 2.5h. After filtration, the mixture was washed twice with 25g of anhydrous toluene and vacuum dried at 55℃ for 1.5h to obtain nano-silica with isocyanate groups on the surface. The obtained powder was then dispersed in 70g of anhydrous ethyl acetate, and 0.8g of glycidyl ether and 0.04g of dibutyltin dilaurate were added dropwise at 30℃. The reaction was continued for 3.5h. After filtration, the mixture was washed twice with anhydrous ethyl acetate and vacuum dried at 35℃ for 3h to obtain nano-silica with glycidyl urethane groups grafted on the surface. Step 2: 280g of polytetramethylene ether glycol with a number average molecular weight of 3000 was placed in a conventional reactor equipped with a stirrer, thermometer, and nitrogen gas introduction. It was dehydrated at 105℃ under vacuum for 1.5h, then cooled to 78℃ and dry nitrogen gas was introduced. 40g of isophorone diisocyanate was added, and the reaction was maintained at 78℃ for 2.5h. Then 2g of nano-silica with glycidyl urethane groups grafted on the surface was added, and the reaction was continued at 72℃ for 0.8h to obtain an isocyanate-terminated polyurethane prepolymer containing a nano-rigid phase. Step 3: Cool the prepolymer obtained in Step 2 to 55°C, add 12g glycidyl ether dropwise over 25 minutes, then maintain the reaction at 55°C for 2.5 hours. After removing trace amounts of volatiles under reduced pressure, cool to 40°C to obtain the end-epoxy polyurethane prepolymer. Step 4: Dissolve 8g of polycaprolactone in 70g of dichloromethane as the oil phase, and dissolve 4g of 2-methylimidazole in 8g of deionized water as the inner aqueous phase; slowly add the inner aqueous phase to the oil phase, and emulsify at 2800r / min for 4min to form a primary emulsion; separately dissolve 2.5g of polyvinyl alcohol in 295g of deionized water to prepare the outer aqueous phase, and slowly add the primary emulsion to the outer aqueous phase at 35℃, stirring at 750r / min for 2.5h; filter, wash twice with deionized water, and vacuum dry at 33℃ for 10h to obtain polycaprolactone-coated 2-methylimidazole latent microcapsules; Step 5: Stir the epoxy polyurethane prepolymer obtained in Step 3 at 40°C, add 7g of polycaprolactone-coated 2-methylimidazole latent microcapsules, mix for 12 minutes, then degas under vacuum for 8 minutes, and then coat it onto a polyester release film at 45°C and flatten it with a cold roller to form a film with a thickness of 0.15mm. Step 6: Lightly sand the upper part and the bonding part of the sole blank with 220-grit sandpaper until they are glossy. After dust removal, wipe with anhydrous ethanol and bake at 45℃ for 2 minutes. Place the adhesive film obtained in Step 5 into the bonding area between the upper and sole. After positioning according to the conventional lasting process, pre-press at 50℃ and 0.15MPa for 25 seconds, then final press at 88℃ and 0.6MPa for 65 seconds, followed by holding the pressure and cooling for 15 seconds. After pressing, cure at 55℃ for 3 hours and then place at room temperature for 24 hours to obtain the lasted waterproof and cold-proof shoe.

[0023] Example 3: Step 1: 9g of nano-silica was vacuum dried at 118℃ for 1.8h, then added to 110g of anhydrous toluene and ultrasonically dispersed for 9min. Under nitrogen protection, 1.8g of 3-isocyanate propyltriethoxysilane was added, and the mixture was stirred at 68℃ for 2.8h. After filtration, the mixture was washed twice with 28g of anhydrous toluene and vacuum dried at 58℃ for 1.8h to obtain nano-silica with isocyanate groups on the surface. The obtained powder was then dispersed in 75g of anhydrous ethyl acetate, and 0.9g of glycidyl ether and 0.045g of dibutyltin dilaurate were added dropwise at 32℃. The reaction was continued for 3.8h, and after filtration, the mixture was washed twice with anhydrous ethyl acetate and vacuum dried at 38℃ for 3.5h to obtain nano-silica with glycidyl urethane groups grafted onto the surface. Step 2: 330g of polytetramethylene ether glycol with a number average molecular weight of 5000 was placed in a conventional reactor equipped with a stirrer, thermometer, and nitrogen gas introduction. It was dehydrated at 108℃ under vacuum for 1.8h, then cooled to 79℃ and dry nitrogen gas was introduced. 48g of isophorone diisocyanate was added, and the reaction was maintained at 79℃ for 2.8h. Then 2.5g of nano-silica with surface grafted glycidyl urethane groups was added, and the reaction was continued at 74℃ for 0.9h to obtain an isocyanate-terminated polyurethane prepolymer containing a nano-rigid phase. Step 3: Cool the prepolymer obtained in Step 2 to 57°C, add 14g of glycidyl ether dropwise over 28 min, then maintain the reaction at 57°C for 2.8 h, remove trace amounts of volatiles under reduced pressure, and cool to 40°C to obtain the end-epoxy polyurethane prepolymer. Step 4: Dissolve 9g of polycaprolactone in 75g of dichloromethane as the oil phase, and dissolve 4.5g of 2-methylimidazole in 9g of deionized water as the inner aqueous phase; slowly add the inner aqueous phase to the oil phase and emulsify at 2900r / min for 4.5min to form a primary emulsion; separately, dissolve 2.8g of polyvinyl alcohol in 296g of deionized water to prepare the outer aqueous phase, and slowly add the primary emulsion to the outer aqueous phase at 36℃ and stir at 780r / min for 2.8h; filter, wash twice with deionized water, and vacuum dry at 34℃ for 11h to obtain polycaprolactone-coated 2-methylimidazole latent microcapsules; Step 5: Stir the epoxy polyurethane prepolymer obtained in Step 3 at 45°C, add 8g of polycaprolactone-coated 2-methylimidazole latent microcapsules, mix for 14min, vacuum degas for 9min, then coat it onto a polyester release film at 45°C and flatten it with a cold roller to form a film with a thickness of 0.18mm. Step 6: Lightly sand the upper part and the bonding part of the sole blank with 200-grit sandpaper until they are glossy. After dust removal, wipe with anhydrous ethanol and bake at 48℃ for 2.5 minutes. Place the adhesive film obtained in Step 5 into the bonding area between the upper part and the sole. After positioning according to the conventional lasting process, pre-press at 53℃ and 0.18MPa for 28 seconds, then final press at 89℃ and 0.65MPa for 68 seconds, followed by holding the pressure and cooling for 18 seconds. After pressing, cure at 58℃ for 3.5 hours and then place at room temperature for 24 hours to obtain the lasted waterproof and cold-proof shoe.

[0024] Example 4: Step 1: 12g of nano-silica was vacuum dried at 120℃ for 2.5h, added to 140g of anhydrous toluene and ultrasonically dispersed for 12min. 2.5g of 3-isocyanate propyltriethoxysilane was added under nitrogen protection, and the mixture was stirred at 75℃ for 3.5h. After filtration, the mixture was washed twice with 35g of anhydrous toluene and vacuum dried at 65℃ for 2.5h to obtain nano-silica with isocyanate groups on the surface. The obtained powder was then dispersed in 90g of anhydrous ethyl acetate, and 1.2g of glycidyl ether and 0.06g of dibutyltin dilaurate were added dropwise at 35℃. The reaction was continued for 4.5h, filtered, washed twice with anhydrous ethyl acetate, and vacuum dried at 45℃ for 5h to obtain nano-silica with glycidyl urethane groups grafted onto the surface. Step 2: 560g of polytetramethylene ether glycol with a number average molecular weight of 6000 was placed in a conventional reactor equipped with a stirrer, thermometer, and nitrogen gas introduction. It was dehydrated at 112℃ under vacuum for 2.5h, then cooled to 82℃ and dry nitrogen gas was introduced. 55g of isophorone diisocyanate was added, and the reaction was maintained at 82℃ for 3.5h. Then 4g of nano-silica with glycidyl urethane groups grafted on the surface was added, and the reaction was continued at 78℃ for 1.2h to obtain an isocyanate-terminated polyurethane prepolymer containing a nano-rigid phase. Step 3: Cool the prepolymer obtained in Step 2 to 60°C, add 18g of glycidyl ether dropwise over 35 minutes, then maintain the reaction at 60°C for 3.5 hours. After removing trace amounts of volatiles under reduced pressure, cool to 40°C to obtain the end-epoxy polyurethane prepolymer. Step 4: Dissolve 12g of polycaprolactone in 90g of dichloromethane as the oil phase, and dissolve 6g of 2-methylimidazole in 12g of deionized water as the inner aqueous phase; slowly add the inner aqueous phase to the oil phase, and emulsify at 3200r / min for 6min to form a primary emulsion; separately dissolve 3.5g of polyvinyl alcohol in 299g of deionized water to prepare the outer aqueous phase, and slowly add the primary emulsion to the outer aqueous phase at 39℃, and stir at 850r / min for 3.5h; filter, wash twice with deionized water, and vacuum dry at 37℃ for 12h to obtain polycaprolactone-coated 2-methylimidazole latent microcapsules; Step 5: Stir the epoxy polyurethane prepolymer obtained in Step 3 at 45°C, add 11g of polycaprolactone-coated 2-methylimidazole latent microcapsules, mix for 18min, vacuum degas for 12min, then coat it onto a polyester release film at 45°C and flatten it with a cold roller to form a film with a thickness of 0.25mm. Step 6: Lightly sand the upper part and the bonding part of the sole blank with 180-grit sandpaper until they are glossy. After dust removal, wipe with anhydrous ethanol and bake at 55℃ for 4 minutes. Place the adhesive film obtained in Step 5 into the bonding area between the upper and sole. After positioning according to the conventional lasting process, pre-press at 60℃ and 0.25MPa for 35 seconds, then final press at 92℃ and 0.8MPa for 75 seconds, followed by holding the pressure and cooling for 25 seconds. After pressing, cure at 65℃ for 5 hours and then place at room temperature for 24 hours to obtain the lasted waterproof and cold-proof shoe.

[0025] Example 5: Step 1: 11g of nano-silica was vacuum dried at 118℃ for 2.2h, then added to 130g of anhydrous toluene and ultrasonically dispersed for 11min. Under nitrogen protection, 2.2g of 3-isocyanate propyltriethoxysilane was added, and the mixture was stirred at 72℃ for 3.2h. After filtration, the mixture was washed twice with 32g of anhydrous toluene and vacuum dried at 62℃ for 2.2h to obtain nano-silica with isocyanate groups on the surface. The obtained powder was then dispersed in 85g of anhydrous ethyl acetate, and 1.1g of glycidyl ether and 0.055g of dibutyltin dilaurate were added dropwise at 33℃. The reaction was continued for 4.2h, and after filtration, the mixture was washed twice with anhydrous ethyl acetate and vacuum dried at 42℃ for 4.5h to obtain nano-silica with glycidyl urethane groups grafted onto the surface. Step 2: 390g of polytetramethylene ether glycol with a number average molecular weight of 4500 was placed in a conventional reactor equipped with a stirrer, thermometer, and nitrogen gas introduction. It was dehydrated at 111℃ under vacuum for 2.2h, then cooled to 81℃ and dry nitrogen gas was introduced. 50g of isophorone diisocyanate was added, and the reaction was maintained at 81℃ for 3.2h. Then 3.5g of nano-silica with surface grafted glycidyl urethane groups was added, and the reaction was continued at 76℃ for 1.1h to obtain an isocyanate-terminated polyurethane prepolymer containing a nano-rigid phase. Step 3: Cool the prepolymer obtained in Step 2 to 59°C, add 16g glycidyl ether dropwise over 32 min, then maintain the reaction at 59°C for 3.2 h, remove trace amounts of volatiles under reduced pressure, and cool to 40°C to obtain the end-epoxy polyurethane prepolymer. Step 4: Dissolve 11g of polycaprolactone in 85g of dichloromethane as the oil phase, and dissolve 5.5g of 2-methylimidazole in 11g of deionized water as the inner aqueous phase; slowly add the inner aqueous phase to the oil phase and emulsify at 3100r / min for 5.5min to form a primary emulsion; separately, dissolve 3.2g of polyvinyl alcohol in 298g of deionized water to prepare the outer aqueous phase, and slowly add the primary emulsion to the outer aqueous phase at 38℃ and stir at 820r / min for 3.2h; filter, wash twice with deionized water, and vacuum dry at 36℃ for 11.5h to obtain polycaprolactone-coated 2-methylimidazole latent microcapsules; Step 5: Stir the epoxy polyurethane prepolymer obtained in Step 3 at 40°C, add 10g of polycaprolactone-coated 2-methylimidazole latent microcapsules, mix for 16min, vacuum degas for 11min, then coat it onto a polyester release film at 45°C and flatten it with a cold roller to form a film with a thickness of 0.22mm. Step 6: Lightly sand the upper part and the bonding part of the sole blank with 180-grit sandpaper until they are glossy. After dust removal, wipe with anhydrous ethanol and bake at 52℃ for 3.5 minutes. Place the adhesive film obtained in Step 5 into the bonding area between the upper and sole. After positioning according to the conventional lasting process, pre-press at 58℃ and 0.22MPa for 32 seconds, then final press at 91℃ and 0.75MPa for 72 seconds, followed by holding the pressure and cooling for 22 seconds. After pressing, cure at 62℃ for 4.5 hours and then place at room temperature for 24 hours to obtain the lasted waterproof and cold-proof shoe.

[0026] Comparative Example 1: The difference between Comparative Example 1 and Example 1 is that the polytetramethylene ether glycol in step 2 is replaced with polytetramethylene ether glycol with a number average molecular weight of 2000, while the other conditions are the same as in Example 1.

[0027] Comparative Example 2: The difference between Comparative Example 2 and Example 1 is that the polytetramethylene ether glycol in step 2 is replaced with polytetramethylene ether glycol with a number average molecular weight of 7000, while the other conditions are the same as in Example 1.

[0028] Comparative Example 3: The difference between Comparative Example 3 and Example 1 is that glycidol is not added in step 3, while the other conditions are the same as in Example 1.

[0029] Comparative Example 4: The difference between Comparative Example 4 and Example 1 is that the 3g of surface-grafted glycidyl urethane-based nano-silica in step 2 was replaced with 3g of nano-silica, while the other conditions were the same as in Example 1.

[0030] Comparative Example 5: The difference between Comparative Example 5 and Example 1 is that: in step 2, 3g of nano-silica with surface-grafted glycidyl carbamate groups is not added, and in step 5, 3g of nano-silica with surface-grafted glycidyl carbamate groups is added at the same time as polycaprolactone-coated 2-methylimidazole latent microcapsules. The other conditions are the same as in Example 1.

[0031] Comparative Example 6: The difference between Comparative Example 6 and Example 1 is that the 9g polycaprolactone-coated 2-methylimidazole latent microcapsules in step 5 were replaced with 6g polycaprolactone and 3g 2-methylimidazole, while the other conditions were the same as in Example 1.

[0032] Comparative Example 7: The difference between Comparative Example 7 and Example 1 is that the pre-compression at 55°C and 0.2MPa for 30s is omitted in step 6, and the final compression at 90°C and 0.7MPa for 70s is carried out directly. The other conditions are the same as in Example 1.

[0033] To conduct performance testing of this invention, the waterproof and cold-proof shoes obtained in Examples 1-5 and Comparative Examples 1-7 were used as whole shoe samples. Simultaneously, to conduct intrinsic characterization and interface performance testing of the samples, the same pretreatment, pressing, and post-curing conditions as in step 6 were used. The adhesive films obtained in step 5 of each example and comparative example were sandwiched between a polyester woven fabric composite polyurethane synthetic leather sheet and an EVA / rubber composite sole sheet after light grinding, dust removal, and wiping with anhydrous ethanol, respectively, to prepare 100mm×25mm upper-sole peel test strips. The adhesive films obtained in step 5 of each example and comparative example were placed between polyester release films and hot-pressed under corresponding pressing temperature, pressure, and post-curing conditions. After peeling off the release film, 40mm×40mm film samples were cut for water absorption testing. Except for low-temperature related items, all samples were placed in a 23℃, 50%RH environment for 48 hours before testing. Low-temperature related items were pretreated in a -20℃ environment for 4 hours before testing.

[0034] Performance testing: Water absorption rate of the adhesive film in 24 hours: Take the cured adhesive film samples obtained from each example and comparative example, and test the water absorption rate according to GB / T 1034-2008; after the 40mm×40mm sample is vacuum dried to constant weight at 50℃, it is placed in a desiccator to cool for 30min, and the initial mass m0 is weighed. Then, the sample is completely immersed in deionized water at 23℃ for 24 hours. After taking it out, the surface moisture is gently absorbed with dust-free filter paper and the mass m1 is weighed within 30s. The water absorption rate in 24 hours is calculated as [(m1-m0) / m0]×100%; each sample is measured in parallel 3 times and the arithmetic mean is taken.

[0035] Initial peel strength: Whole shoe samples prepared in each example and comparative example and left for 48 hours were tested according to GB / T3903.3-2011. Three pairs of shoes were used in each group, with one test site each on the inner forefoot, outer forefoot, and groin area of ​​each pair. The samples were mounted on a whole shoe peel strength testing machine, with the blade width uniformly adjusted to 10mm and the blade speed adjusted to (20±2)mm / min. Peeling was performed continuously from the upper-sole joint until an effective peel length of at least 30mm was achieved. The average force value of the stable peel section was recorded, expressed in N / cm. If no effective peel occurred at 100N / cm, it was recorded as >100N / cm. The average value of the three sites for each pair of shoes was taken, and the arithmetic mean of the three pairs of shoes in each group was taken.

[0036] Low-temperature bending and the retention rate of upper-sole peeling after bending: The whole shoe samples prepared by each example and comparative example were pretreated in an environment of -20℃ for 4 hours, and then the whole shoe flexural endurance test was carried out according to GB / T 3903.1-2017; 3 pairs of shoes were taken from each group and continuously bent 30,000 times on the flexural endurance tester. After the test, the maximum glue separation length and the maximum crack length were measured; at the same time, another 3 pairs of shoes were taken from the same batch of samples and subjected to the same low-temperature pretreatment and bending conditions to complete 30,000 bends. Then, the upper-sole peeling strength after bending was determined according to GB / T 3903.3-2011.

[0037] Dynamic waterproof performance of the whole shoe: Take the whole shoe samples prepared by each example and comparative example, and test the dynamic waterproof performance according to GB / T 16641-2019. Take 3 pairs of shoes in each group; clamp the samples on the dynamic waterproof bending tester, control the test water temperature at 23℃, place the pre-weighed absorbent paper in the forefoot area of ​​the shoe, start the test and bend continuously, set the maximum number of bends to 50,000; record the number of bends corresponding to the first water seepage, and weigh the increase in weight of the absorbent paper at the same time.

[0038] Static waterproof performance of the whole shoe: Take the whole shoe samples prepared by each example and comparative example, and conduct static waterproof evaluation according to the leak-proof and waterproof methods of finished shoes in GB / T 20991-2024. Take 3 pairs of shoes in each group. First, seal the shoe opening, then add 23℃ deionized water into the shoe, so that the liquid level is 20mm away from the upper opening, let it stand for 60 minutes, observe whether leakage occurs in the upper and sole joint area, the forefoot flexion area and the transition area of ​​the welt, and record the time of the first leakage.

[0039] Insulation performance of the whole shoe: Whole shoe samples prepared in each example and comparative example were tested for insulation performance according to GB / T 21284-2015. Two pairs of shoes were used in each group. A foot mold with an initial temperature of 32.0±0.5℃ was placed inside the whole shoe, and then placed in a low-temperature environment chamber at -20±1℃. The temperature of the foot mold was recorded at 0 min, 15 min, 30 min, 45 min, and 60 min. The temperature drop ΔT at 60 min was calculated, and the average value was taken for both left and right feet. The test results are shown in Table 1.

[0040] Table 1 Performance Test Results Data Analysis: As can be seen from the data in Table 1, the waterproof and cold-proof shoes prepared by the present invention achieve comprehensive improvement in terms of film water absorption rate, upper-to-sole peel strength, interface stability after low-temperature bending, and dynamic and static waterproof performance of the entire shoe. It is speculated that the reason is that polytetramethylene ether glycol provides flexible segments that can still deform at low temperatures, glycidyl ether causes epoxy reaction sites to be oriented at the polyurethane chain ends, and the pre-added glyceryl oxycarbamate-modified nano-silica forms a relatively stable nano-rigid phase in the hard segment neighborhood. The polycaprolactone-coated 2-methylimidazole latent microcapsules ensure that curing mainly occurs after pressing and wetting, thus taking into account interface density, waterproof stability, bending crack resistance, and heat preservation performance.

[0041] As can be seen from the data in Table 1 for Examples 1, 1, and 2, when the number-average molecular weight of polytetramethylene ether glycol deviates from the range set in this invention, the overall performance of the bonding region decreases, but the manner of decrease differs. When the number-average molecular weight is low, the urethane segments in the system are relatively dense. Although the initial adhesion can still be maintained at a certain level, molecular chain rotation is restricted at low temperatures, making it more prone to delamination and cracking after bending. When the number-average molecular weight is high, flexibility increases, but the density of effective reaction sites at the chain ends and the interfacial support after compression are insufficient, resulting in a negative impact on initial peel strength and waterproof stability. This indicates that the molecular weight range defined in this invention is not arbitrarily chosen, but rather a balanced window that considers low-temperature flexibility, interfacial density, and subsequent curing efficiency.

[0042] As can be seen from the data in Table 1 for Example 1 and Comparative Example 3, without the addition of glycidol in step 3, several interface-related indicators decreased simultaneously, particularly in terms of peeling after bending and the reduction in waterproof stability. The main reason for this is that glycidol not only provides epoxy reaction sites at the polyurethane chain ends, but also allows the subsequent effect of polycaprolactone-coated 2-methylimidazole latent microcapsules to be effectively released at the interface. Without this structure, subsequent curing makes it difficult to form a sufficiently dense network, and the bonding zone relies more on the physical action of the original polyurethane chain segments, making it more prone to microcrack propagation when exposed to water and bent at low temperatures.

[0043] As can be seen from the data in Table 1 for Examples 1, 4, and 5, adding nano-silica directly as a common filler, or adding it before or after film formation despite surface epoxidation treatment, fails to achieve the comprehensive effect of Example 1. The former, due to its high surface hydroxyl content, has limited compatibility with the polyurethane prepolymer, easily leading to localized agglomeration and the introduction of hydrophilic weak regions. The latter, while retaining surface reactive groups, lacks pre-anchoring in the isocyanate-terminated polyurethane prepolymer stage, making it more difficult for nanoparticles to stably enter the hard segment neighborhood, resulting in insufficient interfacial water-blocking pathways and continuity of force transmission. Therefore, a significant synergistic effect exists between the surface modification of glycerol-oxycarbamate-modified nano-silica and the timing of its addition; only when both are combined can the interfacial density, water resistance, and low-temperature bending stability be simultaneously improved.

[0044] As can be seen from the data in Table 1 for Example 1 and Comparative Example 6, when 2-methylimidazole was added directly to polycaprolactone simultaneously, although curing components were still present in the system, the overall waterproofing and adhesion after bending were significantly reduced. It is speculated that the free 2-methylimidazole promotes the reaction of the epoxy polyurethane prepolymer in the early stages of mixing and heating, causing the adhesive film to cure prematurely in certain areas before the interface is fully wetted. This makes it difficult to fully fill the fine unevenness formed after sanding the upper and sole blanks, resulting in more residual micro-voids after pressing.

[0045] As can be seen from the data in Example 1 and Comparative Example 7 in Table 1, when the material composition remains unchanged, the water absorption rate of the adhesive film does not change significantly after the pre-compression step is removed, but the peeling between the upper and lower surfaces, dynamic waterproofing, and static waterproofing all deteriorate significantly. This indicates that the problem is not mainly with the base material, but with the interface formation process. The pre-compression stage helps the adhesive film soften, spread, and expel trapped air, making the bonding area between the upper and lower surfaces more continuous and denser during the subsequent final compression. If the final compression is performed directly, the areas that are not sufficiently wetted are more likely to become channels for moisture to preferentially penetrate, and stress concentration can be induced during low-temperature bending.

[0046] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention is limited to these examples; within the framework of the invention, the technical features of the above embodiments or different embodiments can also be combined, and there are many other variations of the different aspects of the invention as described above, which are not provided in detail for the sake of brevity.

Claims

1. A type of waterproof and cold-weather shoe with uppers, characterized in that, Includes an upper, a sole, and a cured adhesive layer located between the upper part and the sole bonding part, wherein the cured adhesive layer is formed by pressing and post-curing a waterproof and cold-proof shoe film; The waterproof and cold-proof shoe film is prepared from the following raw materials: 250-560 parts of polytetramethylene ether glycol with a number average molecular weight of 3000-6000, 40-55 parts of isophorone diisocyanate, 2-4 parts of nano-silica with surface grafted glycidyl urethane groups, 12-18 parts of glycidyl urethane and 7-11 parts of polycaprolactone-coated 2-methylimidazole latent microcapsules.

2. The waterproof and cold-proof shoes according to claim 1, characterized in that, The surface-grafted glycidyl carbamate-based nano-silica is obtained by modifying nano-silica with 3-isocyanate propyltriethoxysilane, followed by reaction with glycidyl in the presence of dibutyltin dilaurate; the amounts of nano-silica, 3-isocyanate propyltriethoxysilane, glycidyl and dibutyltin dilaurate, by mass, are 8-12:1.5-2.5:0.8-1.2:0.04-0.

06.

3. The waterproof and cold-proof shoes according to claim 1, characterized in that, The polycaprolactone-coated 2-methylimidazole latent microcapsules are prepared by emulsification of 2-methylimidazole with polycaprolactone and polyvinyl alcohol as a dispersant and stabilizer; the amount of polycaprolactone, 2-methylimidazole and polyvinyl alcohol is 8-12:4-6:2.5-3.5 by mass.

4. The waterproof and cold-proof shoes according to claim 1, characterized in that, The thickness of the adhesive film is 0.15-0.25 mm.

5. The waterproof and cold-proof shoes according to claim 1, characterized in that, The upper is made of polyester woven fabric combined with polyurethane synthetic leather, and the sole is made of EVA / rubber composite cold-proof sole.

6. A method for preparing a waterproof and cold-proof shoe with uppers according to any one of claims 1-5, characterized in that, Includes the following steps: (1) Preparation of nano-silica with glycidyl urethane groups grafted on the surface; (2) Reaction of polytetramethylene ether diol with isophorone diisocyanate, and addition of nano-silica with glycidyl urethane groups grafted on the surface obtained in step (1) to disperse the reaction, to obtain isocyanate-terminated polyurethane prepolymer containing nano-rigid phase. (3) Glycidyl ether is added to the isocyanate-terminated polyurethane prepolymer obtained in step (2) to react and obtain the epoxy-terminated polyurethane prepolymer. (4) Preparation of polycaprolactone-coated 2-methylimidazole latent microcapsules; (5) The epoxy polyurethane prepolymer obtained in step (3) is mixed with the polycaprolactone-coated 2-methylimidazole latent microcapsules obtained in step (4), degassed, and made into a film. (6) Place the adhesive film obtained in step (5) between the upper part of the shoe upper blank and the bonding part of the shoe sole blank. After positioning according to the lasting process, pre-press and then final press; after pressing, cure and then place at room temperature to obtain lasted waterproof and cold-proof shoes.

7. The method for preparing the waterproof and cold-proof shoes according to claim 6, characterized in that, In step (6), the upper part of the shoe blank and the bonding part of the sole blank are lightly sanded with 180-220 grit sandpaper until they are glossy. After dust removal, they are wiped with anhydrous ethanol and baked at 45-55℃ for 2-4 minutes.

8. The method for preparing the waterproof and cold-proof shoes according to claim 6, characterized in that, In step (4), by mass, 8-12 parts of polycaprolactone are dissolved in 70-90 parts of dichloromethane as the oil phase, and 4-6 parts of 2-methylimidazole are dissolved in 8-12 parts of deionized water as the inner aqueous phase. The inner aqueous phase is added to the oil phase and emulsified at 2800-3200 r / min for 4-6 min to form a primary emulsion. Separately, 2.5-3.5 parts of polyvinyl alcohol are dissolved in 295-299 parts of deionized water to prepare an outer aqueous phase. The primary emulsion is added to the outer aqueous phase at 35-39°C and stirred at 750-850 r / min for 2.5-3.5 h. The mixture is then filtered, washed, and vacuum dried at 33-37°C for 10-12 h to obtain polycaprolactone-coated 2-methylimidazole latent microcapsules.

9. The method for preparing the waterproof and cold-proof shoes according to claim 6, characterized in that, In step (6), the pre-pressure is applied at 50-60℃ and 0.15-0.25MPa for 25-35s; the final pressure is applied at 88-92℃ and 0.6-0.8MPa for 65-75s, followed by pressure holding and cooling for 15-25s.

10. The method for preparing the waterproof and cold-proof shoes according to claim 6, characterized in that, In step (6), the curing process is carried out at 55-65℃ for 3-5 hours.

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