Sole sheet with TPU (thermoplastic polyurethane) composite film and preparation method of sole sheet

Abstract

The invention relates to the field of polymer composite materials, in particular to a sole sheet with a TPU (thermoplastic polyurethane) composite film and a preparation method of the sole sheet. S2, preparing a glue solution B; s3, preparing a foamed polymer midsole; step S4, preparing a TPU outsole; and S5, coating the surface of the insole with the glue solution B, coating the surface of the TPU outsole membrane with the glue solution A, laminating the surfaces of the glue A and the glue B, drying, and carrying out hot press molding to obtain the sole sheet with the TPU composite membrane. According to the invention, the problems of low interface bonding strength, poor fatigue resistance and the like of the TPU outsole and the EVA foamed polymer insole are solved.

Description

Technical Field

[0001] The present invention relates to the field of polymer composite materials, and in particular to a shoe sole sheet with a TPU composite film and a preparation method thereof. Background Art

[0002] Traditional shoe soles often combine EVA midsoles with rubber outsoles, but these compounds suffer from issues like low bonding strength, easy delamination, and poor environmental performance. While TPU outsoles are wear-resistant and flex-resistant, they lack compatibility with foam midsoles, and conventional adhesives struggle to withstand repeated bending stress. Existing techniques employing single adhesives or hot-melt adhesives still suffer from drawbacks like insufficient hydrolysis resistance and delamination at high temperatures. Therefore, the development of a novel composite process and specialized adhesive system is urgently needed.

[0003] CN118021035B discloses a high-rebound, environmentally friendly TPU shoe midsole and its preparation method. This TPU shoe midsole comprises a midsole layer (such as EVA, TPU, or nylon) and a thick TPU base layer, bonded together with hot-melt adhesive. A UV-cured elastic resin layer (comprising a polyurethane acrylate polymer and epoxy resin) is coated on the surface of the thick TPU base layer. The thick TPU base layer is synthesized using a mixed diisocyanate (isophorone diisocyanate + modified trimer) to enhance water resistance and mechanical strength. The elastic resin layer contains a UV-cured layer containing a photoinitiator to enhance resilience. However, the elastic modulus between the midsole and outsole is mismatched, resulting in poor compatibility and low peel strength at the bonding interface, resulting in performance shortcomings. Summary of the Invention

[0004] In order to make up for the above shortcomings, the present invention provides a sole sheet with a TPU composite film and a preparation method thereof, which solves the problems of low interface bonding strength and poor fatigue resistance between the TPU outsole and the EVA foam polymer midsole.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions: A method for preparing a sole sheet with a TPU composite film comprises the following steps: Step S1, preparing glue solution A; Step S2, preparing glue solution B; Step S3, preparing a foamed polymer midsole; Step S4, preparing a TPU outsole; Step S5: Apply glue solution B to the midsole surface, apply glue solution A to the TPU outsole film surface, overlap glue solution A and glue solution B, dry and then perform hot pressing to obtain a sole sheet with a TPU composite film.

[0006] Preferably, the process for preparing glue solution A is as follows: adding a mixed solvent A and 3-5 parts by weight of oxazoline-terminated polyester to a reactor, dissolving them at 40°C for 30 minutes, then adding 10-15 parts by weight of a closed HDI trimer, stirring at 35°C for 60 minutes, stirring and dissolving at 35-45°C, adding 0.15-0.25 parts by weight of dibutyltin dilaurate, filtering, and obtaining glue solution A; the solid content of the obtained glue solution A is 18±0.5wt%.

[0007] Preferably, the mixed solvent A is prepared by compounding acetone and butanone in a volume ratio of 7:2-2.8.

[0008] Preferably, the oxazoline-terminated polyester needs to be prepared in advance, comprising the following steps: Synthesis of carboxyl-terminated polyester: Under nitrogen protection, add 45-50 parts of adipic acid, 25-30 parts of 1,4-butanediol, and 0.1-0.2 parts of antioxidant 1010 to the reactor; increase the temperature stepwise: react at 50°C for 1 hour (pre-esterification), 190°C for 4 hours, and 210°C for 2 hours; during the heating process, monitor the acid value and stop the reaction when it is ≤35mgKOH / g; Dehydration under reduced pressure: dehydration at -0.06MPa for 30min; dehydration at -0.095MPa for 60min; stop when the moisture content is ≤200ppm; if dehydration is not thorough, the moisture will cause the oxazoline to open and hydrolyze, resulting in a decrease in the end-capping rate and a high incidence of side reactions, which will lead to reduced water resistance and peel strength. Oxazoline end-capping reaction: After dehydration, cool to 100°C, add 20-25 parts of 2-isopropyl-2-oxazoline (IPOX) as an end-capping agent and 0.4-0.6 parts of p-toluenesulfonic acid (PTSA) as a condensation catalyst; react at 110-120°C for 2.5 hours. Side reactions may occur above 120°C.

[0009] Neutralization and purification: add 6 times the mass of PTSA saturated NaHCO3 solution, stir at 80°C for 30 minutes and let stand to separate the layers. Take the organic phase and distill under reduced pressure at -0.098 MPa and 120°C to remove residual monomers and water to obtain a light yellow viscous liquid, which is the oxazoline-terminated polyester.

[0010] Preferably, the process for preparing the B glue solution is as follows: adding 80-85 parts of mixed solvent B to a dispersion kettle, stirring at 500 rpm, and slowly adding 10±1 parts of maleic anhydride-modified SEBS at the same time, controlling the feeding rate to be ≤1 part / min; heating to 55±5°C, and dispersing at 8000-12000 rpm for 30 minutes; maintaining the temperature at 55±5°C, adding 2.5±0.5 parts of N-hydroxymethyl acrylamide, and dispersing at 5000 rpm for 15 minutes to avoid local overheating and self-polymerization of N-hydroxymethyl acrylamide; cooling to 40±2°C at a rate of 2°C / min, adding 0.7-0.9 parts of DCP, and stirring at 300 rpm for 10 minutes. Excessive speed may cause decomposition of DCP; filtering through a 200-mesh stainless steel filter to remove gel particles to obtain the B glue solution; the solid content of the prepared B glue solution is 15±0.5wt%.

[0011] Preferably, the mixed solvent B is prepared by mixing n-hexane and ethyl acetate in a volume ratio of 8:1.8-2.2.

[0012] Preferably, the preparation process of the foamed polymer midsole comprises the following steps: preheating an internal mixer; sequentially adding, by weight, 50-60 parts by weight of EVA 7470M, 12-17 parts by weight of EVA V33121, 18-22 parts by weight of POE 8150, and 13-17 parts by weight of OBC 9107 into the internal mixer, mixing at 115-130° C. for 3-5 minutes, subsequently adding 3-5 parts by weight of maleic anhydride-modified polyolefin elastomer and 8-12 parts by weight of talc modified with silane coupling agent KH550, and mixing for 2-3 minutes; finally, adding 4-6 parts by weight of zinc oxide, 5-7 parts by weight of a foaming agent, and 1-2 parts by weight of a cross-linking agent, mixing for 2-3 minutes, and calendering to obtain the foamed polymer midsole.

[0013] Preferably, the grafting rate of the maleic anhydride modified polyolefin elastomer is 0.8-1.0 mmol / g; the foaming agent is azodicarbonamide, and the cross-linking agent is tert-butyl peroxyisopropylbenzene.

[0014] Preferably, the preparation process of the TPU outsole comprises the following steps: by weight, 65-75 parts by weight of polyester TPU and 18-22 parts by weight of polyether TPU are mixed and melted; then, 8-10 parts by weight of isocyanate-terminated polyether prepolymer and 3-5 parts by weight of nano zinc oxide are added, and mixed at 135-145°C for 5-8 minutes. If the temperature is higher than 145°C, the NCO in the prepolymer will react prematurely, resulting in uncontrolled cross-linking. If the mixing time is less than 5 minutes, the zinc oxide will be unevenly dispersed and the wear resistance will decrease; then, calendering is performed to obtain the TPU outsole.

[0015] Preferably, the NCO content of the isocyanate-terminated polyether prepolymer is 6-7%.

[0016] Preferably, the specific process of step S5 includes the following steps: S51 substrate pretreatment: The foamed polymer is plasma treated with an atmospheric pressure plasma spray gun to improve the surface energy of the midsole and enhance the wettability of the B glue; the TPU outsole film is wiped with ethanol and preheated at 60°C for 30 seconds with an infrared heating roller to eliminate thermal stress warping.

[0017] S52 double-sided coating: Apply glue B to the bottom surface by slit extrusion coating, with a thickness of 30±2μm and a coating amount of 15±0.5g / m 2 Apply glue A to the large bottom surface of TPU with a micro-gravure roller, with a glue layer thickness of 25±2μm and a coating amount of 12±0.5g / m 2 .

[0018] S53 Drying: Dry in stages after applying the glue; first, dry at a temperature of 50±2℃ and a wind speed of 8m / s for 60s to remove 60% of the volatile matter; then dry at a temperature of 60±1℃ and a wind speed of 12m / s for 120s to make the solvent residue ≤300ppm; finally, dry at a temperature of 45±2℃ and a wind speed of 3m / s for 30s to make the glue layer surface dry; insufficient drying may cause bubbles to form at the interface.

[0019] S54 lamination hot pressing: Laser alignment is used during lamination to minimize errors and prevent stress concentration. The hot pressing temperature is controlled at 115-125 degrees Celsius, the hot pressing pressure is controlled at 9.5-10.5 MPa, and the hot pressing time is 90 seconds. After cooling, the sole sheet with a TPU composite film is obtained.

[0020] In this preparation method, the midsole and TPU outsole are bonded via a dual adhesive system. The dual adhesive system reacts with the midsole and TPU outsole separately, forming an interpenetrating network between the two adhesives. This resolves the low peel strength issue caused by the polarity conflict between the TPU and midsole, significantly enhancing the sheet's peel strength and flex life. The midsole's four-component blend of EVA 7470M (high VA), POE 8150 (low-temperature toughness), and OBC 9107 (melt-reinforced) synergistically improves rebound and reduces compression set.

[0021] During the manufacturing process, parameters at each step must be strictly controlled to ensure material performance. The temperature, pressure, and time settings during the hot-press lamination process must take into account the physical properties of the midsole, adhesive, and outsole to avoid interlayer delamination or deformation.

[0022] This solution also proposes a sole sheet with a TPU composite film prepared by the above preparation solution.

[0023] Compared with the prior art, the present invention has the following advantages: 1. Synergistic enhancement is achieved through a double glue liquid system to resist shear stress: Glue A: After the closed HDI is unblocked, it reacts with the -NCO and -OH of TPU to form a covalent bond; Glue B: The anhydride group of maleic anhydride SEBS is entangled with the midsole polyolefin, and the primary amine reacts with oxazoline at the same time; Glue A and Glue B form an interpenetrating network, and the -NCO of Glue A is cross-linked with the -NH2 of Glue B, constructing a triple force of covalent bond + hydrogen bond + physical entanglement at the interface, and Glue A and Glue B synergistically resist shear stress.

[0024] 2. The high performance of this solution is closely related to the preparation process. Each component of this solution has its own appropriate process range. Exceeding this range may have a negative impact. For example, in the preparation of the TPU outsole, mixing temperature and time are very important. If the temperature is too high, the performance will be greatly reduced. DETAILED DESCRIPTION

[0025] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0026] Unless otherwise specified, the synthesis method of oxazoline polyester described in this scheme is as follows: under nitrogen protection, 48 parts of adipic acid, 28 parts of 1,4-butanediol, and 0.15 parts of antioxidant 1010 are added to a reactor by weight; the temperature is increased stepwise, and the reaction is carried out at 50°C for 1 hour, 190°C for 4 hours, and 210°C for 2 hours; during the heating process, the acid value needs to be monitored, and the reaction is stopped when it is ≤35mgKOH / g, and dehydration is carried out at -0.06MPa for 30min; dehydration is carried out at -0.095MPa for 60mi n; stop when the moisture content is ≤200ppm, cool to 100°C after dehydration, add 23 parts of 2-isopropyl-2-oxazoline (IPOX) and 0.5 parts of p-toluenesulfonic acid (PTSA); react at 110-120°C for 2.5 hours, add saturated NaHCO3 solution (6 times the mass of PTSA), stir at 80°C for 30 minutes, let stand and separate, take the organic phase and distill under reduced pressure at -0.098MPa and 120°C to remove residual monomers and moisture to obtain oxazoline-terminated polyester. Overall embodiment

[0027] A sole sheet with a TPU composite film and a preparation method thereof, comprising the following steps: Step S1, Preparation of Glue A: Add, by weight, a mixed solvent A (volume ratio of acetone: butanone = 7:2-2.8) and 3-5 parts by weight of oxazoline-terminated polyester to a reactor and dissolve at 40°C for 30 minutes. Then, add 10-15 parts by weight of a blocked HDI trimer and stir at 35°C for 60 minutes. After stirring and dissolving at 35-45°C, add 0.15-0.25 parts by weight of dibutyltin dilaurate and filter to obtain glue A; the solid content of glue A is 18±0.5wt%; Step S2, preparation of glue solution B: add 80-85 parts of mixed solvent B (volume ratio of n-hexane:ethyl acetate = 8:1.8-2.2) to a dispersion kettle, stir at 500 rpm, and slowly add 10±1 parts of maleic anhydride-modified SEBS at a feeding rate of ≤1 part / min; heat to 55±5°C, and disperse at 8000-12000 rpm for 30 minutes; maintain the temperature at 55±5°C, add 2.5±0.5 parts of N-hydroxymethyl acrylamide, and disperse at 5000 rpm for 15 minutes; cool to 40±2°C at a rate of 2°C / min, add 0.7-0.9 parts of DCP, and stir at 300 rpm for 10 minutes; filter through a 200-mesh stainless steel filter to remove gel particles to obtain glue solution B; the solid content of glue solution B is 15±0.5wt%; Step S3, preparing a foamed polymer midsole: preheating an internal mixer; placing, by weight, 50-60 parts by weight of EVA 7470M, 12-17 parts by weight of EVA V33121, 18-22 parts by weight of POE 8150, and 13-17 parts by weight of OBC 9107 into an internal mixer, mixing at 115-130° C. for 3-5 minutes, then adding 3-5 parts by weight of a maleic anhydride-modified polyolefin elastomer with a grafting rate of 0.8-1.0 mmol / g and 8-12 parts by weight of talc modified with a silane coupling agent KH550, and mixing for 2-3 minutes; finally, adding 4-6 parts by weight of zinc oxide, 5-7 parts by weight of azodicarbonamide, and 1-2 parts by weight of tert-butyl peroxyisopropylbenzene, mixing for 2-3 minutes, and calendering to obtain a foamed polymer midsole; Step S4, preparing a TPU outsole: by weight, 65-75 parts by weight of polyester TPU and 18-22 parts by weight of polyether TPU are mixed and melted, followed by adding 8-10 parts by weight of an isocyanate-terminated polyether prepolymer having an NCO content of 6-7% and 3-5 parts by weight of nano zinc oxide, and kneading at 135-145° C. for 5-8 minutes, followed by calendering to obtain a TPU outsole; Step S5: Double-sided gluing-hot pressing lamination: S51. Substrate pretreatment: The foamed polymer was plasma treated with an atmospheric pressure plasma spray gun; the TPU base film was wiped with ethanol and preheated with an infrared heating roller at 60°C for 30 seconds; S52. Double-sided glue coating: Apply glue B to the bottom surface by slot extrusion coating, with a glue layer thickness of 30±2μm and a coating amount of 15±0.5g / m 2 Apply glue A to the large bottom surface of TPU with a micro-gravure roller, with a glue layer thickness of 25±2μm and a coating amount of 12±0.5g / m 2 ; S53. Drying: After applying the adhesive, dry the adhesive in stages; first, dry the adhesive at 50±2°C with a wind speed of 8 m / s for 60 seconds to remove 60% of the volatile matter; then, dry the adhesive at 60±1°C with a wind speed of 12 m / s for 120 seconds to reduce the residual solvent to ≤300 ppm; finally, dry the adhesive at 45±2°C with a wind speed of 3 m / s for 30 seconds to allow the adhesive layer to dry. S54. Lamination hot pressing: Laser alignment is used during lamination to minimize errors and prevent stress concentration. The hot pressing temperature is controlled at 115-125°C, the hot pressing pressure is controlled at 9.5-10.5 MPa, and the hot pressing time is 90 seconds. After cooling, the sole sheet with a TPU composite film is obtained. Example 1

[0028] A sole sheet with a TPU composite film and a preparation method thereof, comprising the following steps: Step S1, preparation of glue solution A: adding, by weight, mixed solvent A (acetone: butanone = 7:2.4 by volume) and 4 parts by weight of oxazoline-terminated polyester to a reactor, dissolving at 40°C for 30 minutes, then adding 12 parts by weight of blocked HDI trimer, stirring at 35°C for 60 minutes, adding 0.2 parts by weight of dibutyltin dilaurate after stirring and dissolving at 40°C, and filtering to obtain glue solution A; the solid content of glue solution A is 18wt%; Step S2, preparation of glue solution B: add 52 parts of mixed solvent B (volume ratio of n-hexane:ethyl acetate = 8:2) to a dispersion kettle, stir at 500 rpm, and slowly add 10 parts of maleic anhydride-modified SEBS at the same time, controlling the feeding rate to ≤1 part / min; heat to 55°C, and disperse at 10,000 rpm for 30 minutes; maintain the temperature at 55°C, add 2.5 parts of N-hydroxymethyl acrylamide, and disperse at 5,000 rpm for 15 minutes; cool to 40°C at a rate of 2°C / min, add 0.8 parts of DCP, and stir at 300 rpm for 10 minutes; filter through a 200-mesh stainless steel filter to remove gel particles to obtain glue solution B; the solid content of glue solution B is 15wt%; Step S3, preparing a foamed polymer midsole: preheating an internal mixer; placing 55 parts by weight of EVA7470M, 15 parts by weight of EVA V33121, 20 parts by weight of POE 8150, and 15 parts by weight of OBC 9107 into an internal mixer, mixing at 120° C. for 4 minutes, then adding 4 parts by weight of a maleic anhydride-modified polyolefin elastomer with a grafting rate of 0.9 mmol / g and 10 parts by weight of talc modified with a silane coupling agent KH550, and mixing for 2.5 minutes; finally, adding 5 parts by weight of zinc oxide, 6 parts by weight of azodicarbonamide, and 1.5 parts by weight of tert-butyl peroxyisopropylbenzene, mixing for 2.5 minutes, and calendering to obtain a foamed polymer midsole; Step S4, preparing a TPU outsole: by weight, 70 parts by weight of polyester TPU and 20 parts by weight of polyether TPU were mixed and melted, followed by adding 9 parts by weight of an isocyanate-terminated polyether prepolymer with an NCO content of 6.5% and 4 parts by weight of nano zinc oxide, and kneading at 140° C. for 6 minutes, followed by calendering to obtain a TPU outsole; Step S5, double-sided gluing-drying-hot pressing lamination: S51. Substrate pretreatment: The foamed polymer was plasma treated with an atmospheric pressure plasma spray gun; the TPU base film was wiped with ethanol and preheated with an infrared heating roller at 60°C for 30 seconds; S52. Double-sided glue coating: Apply glue B to the bottom surface by slot extrusion coating, with a glue layer thickness of 30μm and a coating amount of 15g / m 2 ; Apply glue A to the large bottom surface of TPU with a micro-gravure roller, with a glue layer thickness of 25μm and a coating amount of 12g / m 2 ; S53. Drying: After applying the adhesive, dry the adhesive in stages; first, dry the adhesive at 50°C with a wind speed of 8 m / s for 60 seconds to remove 60% of the volatile matter; then, dry the adhesive at 60°C with a wind speed of 12 m / s for 120 seconds to reduce the residual solvent to ≤ 300 ppm; finally, dry the adhesive at 45°C with a wind speed of 3 m / s for 30 seconds to dry the adhesive layer. S54. Lamination and Hot Pressing: Laser alignment is used during lamination to minimize errors and prevent stress concentration. The hot pressing temperature is controlled at 120°C, the hot pressing pressure is controlled at 10.0 MPa, and the hot pressing time is controlled at 90 seconds. After cooling, the sole sheet with the TPU composite film is obtained. Example 2

[0029] A sole sheet with a TPU composite film and a preparation method thereof, comprising the following steps: Step S1, Preparation of Glue A: Add, by weight, a mixed solvent A (acetone:butanone = 7:2.4 by volume) and 3 parts by weight of oxazoline-terminated polyester to a reactor and dissolve at 40°C for 30 minutes. Then, add 10 parts by weight of a blocked HDI trimer and stir at 35°C for 60 minutes. After stirring and dissolving at 38°C, add 0.15 parts by weight of dibutyltin dilaurate and filter to obtain glue A; the solid content of glue A is 18.2 wt%; Step S2, preparation of glue solution B: add 52 parts of mixed solvent B (volume ratio of n-hexane:ethyl acetate = 8:2) to a dispersion kettle, stir at 500 rpm, and slowly add 10 parts of maleic anhydride-modified SEBS at the same time, controlling the feeding rate to ≤1 part / min; heat to 55°C, and disperse at 10,000 rpm for 30 minutes; maintain the temperature at 55°C, add 2.5 parts of N-hydroxymethyl acrylamide, and disperse at 5,000 rpm for 15 minutes; cool to 40°C at a rate of 2°C / min, add 0.8 parts of DCP, and stir at 300 rpm for 10 minutes; filter through a 200-mesh stainless steel filter to remove gel particles to obtain glue solution B; the solid content of glue solution B is 15.3wt%; Step S3, preparing a foamed polymer midsole: preheating an internal mixer; placing 50 parts by weight of EVA7470M, 15 parts by weight of EVA V33121, 18 parts by weight of POE 8150, and 15 parts by weight of OBC 9107 into an internal mixer, mixing at 120° C. for 4 minutes, then adding 4 parts by weight of a maleic anhydride-modified polyolefin elastomer with a grafting rate of 0.9 mmol / g and 10 parts by weight of talc modified with a silane coupling agent KH550, and mixing for 2.5 minutes; finally, adding 5 parts by weight of zinc oxide, 6 parts by weight of azodicarbonamide, and 1.5 parts by weight of tert-butyl peroxyisopropylbenzene, mixing for 2.5 minutes, and calendering to obtain a foamed polymer midsole; Step S4, preparing a TPU outsole: by weight, 70 parts by weight of polyester TPU and 20 parts by weight of polyether TPU were mixed and melted, followed by adding 9 parts by weight of an isocyanate-terminated polyether prepolymer with an NCO content of 6.5% and 4 parts by weight of nano zinc oxide, and kneading at 140° C. for 6 minutes, followed by calendering to obtain a TPU outsole; Step S5, double-sided gluing-drying-hot pressing lamination: S51. Substrate pretreatment: The foamed polymer was plasma treated with an atmospheric pressure plasma spray gun; the TPU base film was wiped with ethanol and preheated with an infrared heating roller at 60°C for 30 seconds; S52. Double-sided glue coating: Apply glue B to the bottom surface by slot extrusion coating, with a glue layer thickness of 30μm and a coating amount of 15g / m 2 ; Apply glue A to the large bottom surface of TPU with a micro-gravure roller, with a glue layer thickness of 25μm and a coating amount of 12g / m2 ; S53. Drying: After applying the adhesive, dry the adhesive in stages; first, dry the adhesive at 50°C with a wind speed of 8 m / s for 60 seconds to remove 60% of the volatile matter; then, dry the adhesive at 60°C with a wind speed of 12 m / s for 120 seconds to reduce the residual solvent to ≤ 300 ppm; finally, dry the adhesive at 45°C with a wind speed of 3 m / s for 30 seconds to dry the adhesive layer. S54. Lamination and Hot Pressing: Laser alignment is used during lamination to minimize errors and prevent stress concentration. The hot pressing temperature is controlled at 115°C, the hot pressing pressure is controlled at 9.5 MPa, and the hot pressing time is controlled at 90 seconds. After cooling, the sole sheet with the TPU composite film is obtained. Example 3

[0030] A sole sheet with a TPU composite film and a preparation method thereof, comprising the following steps: Step S1, Preparation of Glue A: Add, by weight, a mixed solvent A (acetone:butanone = 7:2.4 by volume) and 5 parts by weight of oxazoline-terminated polyester to a reactor and dissolve at 40°C for 30 minutes. Then, add 15 parts by weight of a blocked HDI trimer and stir at 35°C for 60 minutes. After stirring and dissolving at 40°C, add 0.25 parts by weight of dibutyltin dilaurate and filter to obtain glue A; the solid content of glue A is 17.8 wt%; Step S2, preparation of glue solution B: add 52 parts of mixed solvent B (volume ratio of n-hexane:ethyl acetate = 8:2) to a dispersion kettle, stir at 500 rpm, and slowly add 10 parts of maleic anhydride-modified SEBS at the same time, controlling the feeding rate to ≤1 part / min; heat to 55°C, and disperse at 10,000 rpm for 30 minutes; maintain the temperature at 55°C, add 2.5 parts of N-hydroxymethyl acrylamide, and disperse at 5,000 rpm for 15 minutes; cool to 40°C at a rate of 2°C / min, add 0.8 parts of DCP, and stir at 300 rpm for 10 minutes; filter through a 200-mesh stainless steel filter to remove gel particles to obtain glue solution B; the solid content of glue solution B is 14.6wt%; Step S3, preparing a foamed polymer midsole: preheating an internal mixer; placing 55 parts by weight of EVA7470M, 17 parts by weight of EVA V33121, 20 parts by weight of POE 8150, and 17 parts by weight of OBC 9107 into an internal mixer, mixing at 120° C. for 4 minutes, then adding 4 parts by weight of a maleic anhydride-modified polyolefin elastomer with a grafting rate of 0.9 mmol / g and 10 parts by weight of talc modified with a silane coupling agent KH550, and mixing for 2.5 minutes; finally, adding 5 parts by weight of zinc oxide, 6 parts by weight of azodicarbonamide, and 1.5 parts by weight of tert-butyl peroxyisopropylbenzene, mixing for 2.5 minutes, and calendering to obtain a foamed polymer midsole; Step S4, preparing a TPU outsole: by weight, 70 parts by weight of polyester TPU and 20 parts by weight of polyether TPU were mixed and melted, followed by adding 9 parts by weight of an isocyanate-terminated polyether prepolymer with an NCO content of 6.5% and 4 parts by weight of nano zinc oxide, and kneading at 140° C. for 6 minutes, followed by calendering to obtain a TPU outsole; Step S5, double-sided gluing-drying-hot pressing lamination: S51. Substrate pretreatment: The foamed polymer was plasma treated with an atmospheric pressure plasma spray gun; the TPU base film was wiped with ethanol and preheated with an infrared heating roller at 60°C for 30 seconds; S52. Double-sided glue coating: Apply glue B to the bottom surface by slot extrusion coating, with a glue layer thickness of 30μm and a coating amount of 15g / m 2 ; Apply glue A to the large bottom surface of TPU with a micro-gravure roller, with a glue layer thickness of 25μm and a coating amount of 12g / m 2 ; S53. Drying: After applying the adhesive, dry the adhesive in stages; first, dry the adhesive at 50°C with a wind speed of 8 m / s for 60 seconds to remove 60% of the volatile matter; then, dry the adhesive at 60°C with a wind speed of 12 m / s for 120 seconds to reduce the residual solvent to ≤ 300 ppm; finally, dry the adhesive at 45°C with a wind speed of 3 m / s for 30 seconds to dry the adhesive layer. S54. Lamination and hot pressing: Laser alignment is used during lamination to minimize errors and prevent stress concentration. The hot pressing temperature is controlled at 125°C, the hot pressing pressure is controlled at 10.5 MPa, and the hot pressing time is controlled at 90 seconds. After cooling, the sole sheet with a TPU composite film is obtained.

[0031] Comparative Example 1 The difference from Example 1 is that the oxazoline polyester is replaced by the terminal hydroxyl polyester in glue A.

[0032] Comparative Example 2 The difference from Example 1 is that DCP in glue B is eliminated.

[0033] Comparative Example 3 The difference from Example 1 is that glue A is eliminated and only glue B is used.

[0034] Comparative Example 4 The difference from Example 1 is that glue B is eliminated and only glue A is used.

[0035] Comparative Example 5 The difference from Example 1 is that the hot pressing temperature is reduced to 110°C.

[0036] Comparative Example 6 The difference from Example 1 is that the hot pressing temperature is increased to 130°C.

[0037] Comparative Example 7 The difference from Example 1 is that no prepolymer is added to the TPU outsole.

[0038] Comparative Example 8 The difference from Example 1 is that during the preparation of the TPU outsole, the mixing temperature is too high: Step S4, preparing a TPU outsole: by weight, 70 parts by weight of polyester TPU and 20 parts by weight of polyether TPU were mixed and melted, followed by adding 9 parts by weight of an isocyanate-terminated polyether prepolymer with an NCO content of 6.5% and 4 parts by weight of nano zinc oxide. The mixture was kneaded at 160° C. for 6 minutes, and then calendered to obtain a TPU outsole.

[0039] Detection method: Peel strength test: Refer to GB / T2791-1995, cut a 200mm × 25mm specimen, apply glue to one end of the specimen, and place release tape on the non-adhesive area. Clamp the non-adhesive ends of the specimen symmetrically between the upper and lower clamps, and peel at a rate of 100±10mm / min. Record the peel strength in N / mm.

[0040] Rebound rate test: Take a square specimen with a side length of 80mm, mark the center as the test point, and condition it in an environment with a temperature of 23±2℃ and a relative humidity of 50±10% for ≥4 hours. Use a stainless steel spherical impact head with a mass of 8.50±0.01kg, a diameter of 45.0±0.5mm, and a spherical radius of 37.5±0.5mm. Adjust the impact device base to a horizontal level, ensure that the impact guide rod is vertical, align the mark point with the center of the impact head, fix the specimen with a clamp, and lift the impact head until the displacement sensor shows h 0= Release the impact head at 50.0±0.5mm and let it fall freely. After impact, it stays for 2±1 seconds to reset. Repeat this 5 times. Only the valid data of the last 3 times are taken. The maximum rebound height h is recorded and the rebound rate is calculated.

[0041] Wear resistance test: Refer to GB / T3903.2. A rotating T12 steel grinding wheel rubs the specimen surface under vertical pressure. After a set wear time, the wear scar length is measured. The longer the wear scar, the worse the wear resistance. Take a specimen with a thickness of 6mm or more, remove surface impurities, and condition at room temperature for ≥4 hours, avoiding direct sunlight. Fix the specimen with the large bottom side facing up to the left end of the testing machine balance. Adjust the level to ensure that the worn area is flat. Align the grinding wheel with the flat area of ​​the specimen. After zeroing the balance, add a 500g weight to the right end to make the grinding wheel contact the specimen. Set the speed to 191 r / min, wear for 20 minutes, and after automatic shutdown, use a vernier caliper to measure the length of both edges of the wear scar.

[0042] Compression deformation test: refer to ISO1856, place the sample in a compression fixture and place it in a constant temperature box at 70℃ for 22 hours. The sample is allowed to recover in an environment of 23℃. The thickness after recovery is measured and the compression deformation rate is calculated.

[0043] Bending life test: refer to SATRATM92, use a bending tester to test at -20℃, and record the bending life.

[0044] Hygrothermal aging rate test: The sample was placed in an 85℃ / 85%RH environment for 72 hours and then the strength was measured.

[0045] The test results are recorded in Table 1.

[0046] Table 1 Performance test results of examples and comparative examples

[0047] The embodiment of the scheme greatly improves the problem of poor compatibility between the TPU outsole and the EVA midsole by designing two types of glue A / B as a transition layer. Further, through process control and interface optimization, a composite sole with balanced performance is achieved, which has great advantages over traditional solutions and even comparative examples.

[0048] The performance disadvantages of each comparative example relative to Example 1 are due to the destruction of the core reaction mechanism and the decrease in structural stability caused by the lack of key materials and processes: in Comparative Example 1, the terminal hydroxy polyester replaces the oxazoline polyester, which loses the ring-opening addition ability of its closed-ring group to maleic anhydride during hot pressing, causing a sharp drop in the chemical crosslinking density; in Comparative Example 2, the cancellation of DCP makes the crosslinking reaction of N-hydroxymethyl acrylamide in the SEBS phase initiated by free radicals fail, resulting in the weakening of the cohesive energy of the rubber phase; in Comparative Example 3 / 4, the single glue liquid fails to reconcile and solve the compatibility problem of TPU and EVA, so the transition layer bonding effect is poor and the peel strength is low; in Comparative Example 5, the hot pressing temperature is insufficient to inhibit the ring-opening efficiency of the oxazoline ring, resulting in incomplete curing, and in Comparative Example 6, the excessively high temperature triggers the foaming of the bottom polymer. The molecular chain of the compound is broken; in Comparative Example 7, the TPU prepolymer is cancelled, which destroys the in-situ bonding effect between the isocyanate group and the active hydrogen of the adhesive layer, and the penetration of interface molecules is hindered; in Comparative Example 8, the mixing temperature of the TPU outsole is increased to 160°C, which triggers multiple chain failures: the excessively high temperature domain first causes the NCO groups in the isocyanate-terminated prepolymer to self-polymerize in advance to form rigid brittle cross-linked clusters, which not only consumes the key active sites that react with the oxazoline groups of the A glue, but also triggers the β-fracture of the ester group in the polyester TPU molecular chain and the oxidative cracking of the polyether chain segment; nano-zinc oxide is converted into a Lewis acid catalytic center at high temperature, which accelerates the condensation of the decomposition products of the prepolymer and the broken chain residues of the TPU to form a metal complex with poor thermal stability, causing the matrix phase to switch from tough-plastic equilibrium to brittle fracture.

Claims

1. A method for preparing a sole sheet with a TPU composite film, characterized in that: The following steps are involved: Step S1, preparing glue solution A: Add a mixed solvent A to a reactor, wherein the mixed solvent A comprises acetone and butanone in a volume ratio of 7:2.8-3.2; then add 10-15 parts by weight of a blocked HDI trimer and 3-5 parts by weight of an oxazoline-terminated polyester; stir and dissolve at 35-45° C., then add 0.15-0.25 parts by weight of dibutyltin dilaurate, and filter to obtain a glue solution A with a solid content of 18±0.5wt%; Step S2, preparing glue solution B: In parts by weight, a mixed solvent B was added to the dispersion vessel, wherein the mixed solvent B was a volume ratio of 8:1.8-2.2 of n-hexane - ethyl acetate, followed by the addition of 10 ± 1 parts by mass of a maleic anhydride-modified styrene-ethylene-butylene-styrene block copolymer with a grafting rate of 1.6-2.0%, 2.5 ± 0.5 parts by mass of N-hydroxymethyl acrylamide, and dispersed at 50-60 ° C with high shear, then cooled to 38-42 ° C and 0.7-0.9 parts by mass of diisopropyl benzene peroxide was added and filtered to obtain a solid content of 15 ± 0.5wt% of B glue; Step S3, preparing a foamed polymer midsole; Step S4, preparing a TPU outsole; Step S5: Apply glue solution B to the midsole surface, apply glue solution A to the TPU outsole film surface, overlap glue solution A and glue solution B, dry and then perform hot pressing to obtain a sole sheet with a TPU composite film.

2. The method for preparing a sole sheet having a TPU composite film according to claim 1, wherein: The preparation process of the foamed polymer midsole comprises the following steps: The method comprises the following steps: mixing 50-60 parts by weight of EVA 7470M, 12-17 parts by weight of EVA V33121, 18-22 parts by weight of POE8150, and 13-17 parts by weight of OBC 9107, and kneading the mixture at 115-130° C. for 3-5 minutes; then adding 3-5 parts by weight of a maleic anhydride-modified polyolefin elastomer and 8-12 parts by weight of talc powder modified with a silane coupling agent KH550, and kneading the mixture for 2-3 minutes; finally, adding 4-6 parts by weight of zinc oxide, 5-7 parts by weight of a foaming agent, and 1-2 parts by weight of a cross-linking agent, and kneading the mixture for 2-3 minutes, followed by calendaring to obtain a foamed polymer midsole.

3. The method for preparing a shoe sole sheet having a TPU composite film according to claim 2, wherein: The grafting rate of the maleic anhydride modified polyolefin elastomer is 0.8-1.0 mmol / g; the foaming agent is azodicarbonamide, and the crosslinking agent is tert-butyl peroxyisopropylbenzene.

4. The method for preparing a sole sheet having a TPU composite film according to claim 1, wherein: The preparation process of the TPU outsole comprises the following steps: By weight, 65-75 parts by weight of polyester TPU and 18-22 parts by weight of polyether TPU are mixed and melted, and then 8-10 parts by weight of isocyanate-terminated polyether prepolymer and 3-5 parts by weight of nano zinc oxide are added. The mixture is kneaded at 135-145°C for 5-8 minutes, and then calendered to obtain a TPU outsole.

5. The method for preparing a sole sheet having a TPU composite film according to claim 4, wherein: The NCO content of the isocyanate-terminated polyether prepolymer is 6-7%.

6. A sole sheet with a TPU composite film prepared by the method for preparing a sole sheet with a TPU composite film according to any one of claims 1 to 5.

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