TPU (thermoplastic polyurethane) composite film for integrally forming and preparing sole and preparation method of TPU composite film

Abstract

The invention relates to the field of shoe materials, and particularly discloses a TPU composite film for integrally forming and preparing shoe soles and a preparation method thereof, the TPU composite film comprises the following raw materials: TPU particles, SEBS leftover materials, an antioxidant, an ultraviolet light absorber, a light stabilizer, a lubricant, a reinforcing filler, an adhesion promoter and a heat-resistant modifier; wherein the heat-resistant modifier is a mixture of polycarbonate diol and a graphene oxide-hydroxyl organic silicon modifier composite filler, and the graphene oxide-hydroxyl organic silicon modifier composite filler is prepared by adding hydroxyl-terminated polydimethylsiloxane into an ethanol water solution added with a silane coupling agent and graphene oxide to react and then drying; the preparation method comprises the following steps: fully and uniformly mixing the raw materials, then carrying out melt blending, and then carrying out film casting to prepare the TPU composite film. The TPU composite film has the characteristics that the TPU composite film with more excellent heat resistance and yellowing resistance is prepared, so that the requirement of integrally forming and preparing a sole is met.

Description

Technical Field

[0001] This application relates to the field of footwear materials, and more specifically, to a TPU composite film for one-piece molding of shoe soles and a method for preparing the same. Background Technology

[0002] In the footwear manufacturing industry, the sole, as a key component, directly affects the comfort, durability, and functionality of shoes. Traditional soles typically consist of an outsole and a midsole. The outsole provides abrasion resistance and slip resistance, while the midsole offers cushioning and support. However, in the traditional sole manufacturing process, the outsole and midsole need to be made separately and then glued together, a complex and energy-intensive process. Furthermore, defects such as air bubbles and pitting are prone to occur at the bonding interface. Moreover, traditional sole materials like rubber often struggle to balance abrasion resistance and flexibility, resulting in short product lifespans or poor comfort. For example, while rubber outsoles are abrasion-resistant, they lack flexibility, while EVA midsoles are soft but have poor abrasion resistance.

[0003] As consumers increasingly demand higher performance, comfort, and environmental friendliness in footwear products, the footwear manufacturing industry urgently needs to develop new materials and manufacturing processes. TPU (thermoplastic polyurethane), as a high-performance elastomer, is an ideal choice for shoe sole materials due to its excellent abrasion resistance, flexibility, chemical resistance, and biocompatibility. To address these issues, research has begun on using TPU materials for one-piece molding of shoe soles.

[0004] Currently, the common method for manufacturing one-piece shoe soles is to combine the outsole and midsole of the sole in the same mold through a specific process to form a complete sole structure. For example, in related technologies, a TPU composite film is laid on the bottom of the mold and made to fit tightly against the mold surface. Then, PU foam material is injected into the mold and covered on the TPU composite film. Foaming and molding are carried out in the mold. The heat and pressure generated during the foaming process make the PU foam material and the TPU composite film fit tightly together, forming the shape and texture of the sole. After the foam material solidifies and the mold is cooled, the sole is demolded to obtain a one-piece shoe sole.

[0005] When the aforementioned TPU composite film is used in the preparation of one-piece molded shoe soles, it needs to have good heat resistance. During the molding process, the TPU composite film and PU foam are molded simultaneously in the mold. The TPU composite film with excellent heat resistance can avoid material deformation or performance degradation caused by high temperature, ensuring the stability of the molding process and the consistency of the product. In addition, the TPU composite film needs to further improve its yellowing resistance. Yellowing resistance can ensure that the shoes maintain their original color and appearance under long-term wear and daily sunlight, extending the aesthetic life of the shoes. Summary of the Invention

[0006] In order to obtain a TPU composite film with better heat resistance and yellowing resistance to meet the requirements of one-piece molding of shoe soles, this application provides a TPU composite film for one-piece molding of shoe soles and a method for preparing the same.

[0007] In a first aspect, this application provides a TPU composite film for integral molding of shoe soles, employing the following technical solution: A TPU composite film for one-piece molding of shoe soles comprises the following raw materials in parts by weight: 60-80 parts TPU granules, 15-30 parts SEBS scraps, 1-3 parts antioxidant, 0.5-2 parts UV absorber, 0.5-2 parts light stabilizer, 0.5-2 parts lubricant, 5-15 parts reinforcing filler, 1-3 parts adhesion promoter and 8-15 parts heat-resistant modifier; Among them, the heat-resistant modifier is selected from polycarbonate diol and graphene oxide-hydroxyl organosilicon modifier composite filler. The graphene oxide-hydroxyl organosilicon modifier composite filler is prepared by adding hydroxyl-terminated polydimethylsiloxane into an ethanol aqueous solution containing silane coupling agent and graphene oxide, reacting and then drying.

[0008] By adopting the above technical solution, the TPU composite film in this application is mainly composed of TPU particles, supplemented with modified SEBS scrap. SEBS is obtained by hydrogenating special linear SBS to saturate the double bonds. The carbon-carbon double bonds of the butadiene segment are hydrogenated and saturated, thus exhibiting good weather resistance, heat resistance, compression set resistance, and excellent mechanical properties, especially excellent aging resistance and yellowing resistance. Adding it as an auxiliary filler can improve the yellowing resistance of the TPU composite film. In addition, the addition of antioxidants captures free radicals generated by thermo-oxidative aging, terminating the chain reaction. The ultraviolet absorber absorbs ultraviolet light, reducing the photo-induced breakage of TPU segments. The light stabilizer decomposes hydrogen peroxide, inhibiting photo-oxidative degradation. Moreover, the benzene ring structure in the SEBS scrap can absorb some ultraviolet light, reducing the photo-degradation of TPU. The final TPU composite film has excellent yellowing resistance.

[0009] In this application, to improve the heat resistance of TPU composite films, polycarbonate diol in the heat-resistant modifier restricts the movement of molecular chains at high temperatures through hydrogen bonding between its rigid carbonate groups and the soft segments of TPU, thereby improving its heat resistance. The addition of graphene oxide-hydroxyl organosilicon modifier composite filler allows the two-dimensional sheet structure of graphene oxide to form a physical barrier, hindering heat conduction. Moreover, the oxygen-containing functional groups on its surface can form chemical bonds with TPU segments, enhancing thermal stability. Hydroxyl-terminated polydimethylsiloxane is a multifunctional organosilicon polymer with hydroxyl groups at both ends of its molecular chain, enabling it to react with TPU containing isocyanate groups to form a cross-linked structure. Furthermore, the silicon-oxygen bonds significantly improve its thermal stability. The addition of a silane coupling agent allows graphene oxide to graft with hydroxyl-containing silane to form a three-dimensional network structure, improving its thermal barrier properties and ultimately significantly enhancing its heat resistance.

[0010] In this application, graphene oxide and hydroxyl-containing organosilicon are added in a composite manner. Compared with the direct addition of the two, the abundant oxygen-containing functional groups on the surface of graphene oxide result in strong interlayer molecular forces, making it prone to agglomeration in the TPU matrix, leading to uneven dispersion and affecting its performance improvement. By combining graphene oxide with hydroxyl-containing organosilicon, the hydroxyl-containing organosilicon coats the surface of graphene oxide, reducing its surface energy and improving its dispersibility in the TPU matrix. This allows graphene oxide to be uniformly dispersed in the TPU matrix, forming an effective heat-insulating network and improving its thermal stability. Ultimately, the TPU composite film prepared in this application has excellent anti-yellowing properties as well as excellent heat resistance, which is beneficial for subsequent integral molding processing and product performance improvement.

[0011] Optionally, the graphene oxide-hydroxyl organosilicon modifier composite filler is prepared by the following method: Graphene oxide was dissolved in water and then ultrasonically dispersed to obtain a graphene oxide solution. Then, an ethanol aqueous solution of silane coupling agent was added, mixed and dispersed to obtain a preliminary mixture. Hydroxyl-terminated polydimethylsiloxane was dissolved in carbon tetrachloride to prepare an organosilicon solution. The organosilicon solution was then added to the initial mixture, heated to 60-80℃, and the pH was adjusted to 4-6. After stirring for 2-3 hours, the mixture was distilled under reduced pressure, dried under vacuum, and then heat-treated at 120-130℃ for 1-2 hours before washing and drying to obtain a graphene oxide-hydroxyl organosilicon modifier composite filler.

[0012] By adopting the above technical solution, this application first prepares a preliminary mixture. The silane coupling agent hydrolyzes in the preliminary mixture to generate silanol groups, which condense with the hydroxyl or carboxyl groups on the surface of graphene oxide to form covalent bonds. At the same time, the amino and epoxy groups at the other end of the silane coupling agent react with the hydroxyl groups of the hydroxyl-terminated polydimethylsiloxane under acidic conditions to achieve the anchoring of hydroxyl organosilicon on the surface of graphene oxide. In addition, the hydroxyl groups in the hydroxyl organosilicon can also form hydrogen bonds with the functional groups of graphene oxide. Meanwhile, long-chain molecules are wrapped around the graphene oxide sheets to form physical coating, which ultimately improves the aggregation phenomenon of graphene oxide. Moreover, the synergy of the two has a better effect on improving heat resistance.

[0013] Optionally, in the preparation process of graphene oxide-hydroxyl organosilicon modifier composite filler, the amount of silane coupling agent added is 1-3 wt% of graphene oxide, the mass ratio of graphene oxide to water is 1:(5-6), and the amount of ethanol aqueous solution added is 3-4 times the mass of silane coupling agent. The ethanol aqueous solution is obtained by mixing ethanol and water at a volume ratio of 1:(1-1.2). The mass ratio of hydroxyl-terminated polydimethylsiloxane to graphene oxide is 1:(1.2-1.3), and the hydroxyl-terminated polydimethylsiloxane is dissolved in 1-2 times the mass of carbon tetrachloride.

[0014] By adopting the above technical solution, the above-mentioned addition amount control achieves the coating of graphene oxide with hydroxyl organosilicon, resulting in better performance of TPU composite film.

[0015] Optionally, in the preparation process of graphene oxide-hydroxyl organosilicon modifier composite filler, after mixing and dispersing the ethanol aqueous solution with silane coupling agent, PAMAM is also added to obtain a preliminary mixture, and the amount of PAMAM added is 3-5 wt% of the amount of graphene oxide added.

[0016] By adopting the above technical solution, in this application, when preparing graphene oxide and hydroxyl organosilicon composite, PAMAM with polyamino groups is added to the initial mixture. This introduces amino groups into the graphene oxide, which can also chemically react with the hydroxyl groups in the hydroxyl organosilicon, thereby enhancing the interaction between the graphene oxide and the hydroxyl organosilicon and forming a more stable composite structure. This helps to reduce yellowing. Moreover, TPU undergoes an oxidation reaction under the action of light, heat, oxygen, etc., producing free radicals and other active substances, which leads to yellowing. In this application, the introduction of amino groups into the graphene oxide can react with the free radicals generated during the oxidation process, inhibiting the chain reaction of free radicals, reducing the generation of oxidation products, thereby delaying the yellowing process of the TPU film and improving its yellowing resistance.

[0017] Furthermore, the introduction of amino groups gives it better stability at high temperatures. The amino groups in graphene oxide form a stronger interaction with the TPU molecular chains, restricting the movement of the molecular chains and thus improving the heat resistance of the TPU film. Moreover, the amino groups can promote the dispersion and orientation of graphene oxide in the TPU matrix, resulting in a TPU film with better overall performance in terms of yellowing resistance and heat resistance.

[0018] Optionally, the SEBS scrap is added after modification treatment, specifically as follows: After cleaning and drying SEBS scraps, they are added to toluene solvent. The temperature is then raised to 90-110℃, and an initiator and ethyl isocyanate acrylate are added dropwise. After reacting for 40-60 minutes, the temperature is raised to 110-130℃, and maleic anhydride is added dropwise. The mixture is stirred and reacted for 1-2 hours under nitrogen protection. Then, the mixture is added to ethanol to precipitate the precipitate. The precipitate is then washed with ethanol and dried under vacuum to obtain modified SEBS scraps.

[0019] By adopting the above technical solution, this application uses ethyl isocyanate and maleic anhydride as modifiers to modify SEBS scraps. Ethyl isocyanate contains isocyanate groups and carbon-carbon double bonds. Under the action of an initiator, the SEBS molecular chain generates free radicals, forming large SEBS molecular free radicals, which have excellent reactivity. These free radicals attack the isocyanate groups in the ethyl isocyanate molecule, causing the unsaturated bonds of the carbon atoms to break after nucleophilic attack, forming new chemical bonds with the large SEBS molecular free radicals. This grafts the polar functional group ethyl acrylate onto the SEBS molecular chain, interacting with the polar groups on the TPU molecular chain. The use of this material enhances the interfacial adhesion between SEBS and TPU, significantly improving their compatibility and enabling their blending. Furthermore, the introduction of maleic anhydride introduces carboxyl polar ligands into the SEBS molecular chain, which can form hydrogen bonds with the TPU molecular chain, further improving the compatibility between SEBS and TPU. Moreover, the isocyanate groups and carboxyl groups in the modified SEBS can form chemical bonds with the hydroxyl groups on the TPU molecular chain, creating a cross-linked structure between SEBS and TPU. This restricts molecular chain movement, reduces the possibility of thermal oxidative degradation, and further improves the heat resistance and yellowing resistance of the composite film.

[0020] Optionally, when preparing modified SEBS scrap, the mass ratio of SEBS scrap to toluene solvent is 1:(3-4), the amount of initiator added is 0.5-2wt% of SEBS scrap, and the mass ratio of ethyl isocyanate acrylate, maleic anhydride and SEBS scrap is 1:(2-3):(6-8).

[0021] Optionally, during the preparation of modified SEBS scrap, before adding the initiator and ethyl isocyanate acrylate, hindered phenolic antioxidant 1010 is added first, and the amount of hindered phenolic antioxidant added is 0.1-0.5 wt% of the amount of SEBS scrap added.

[0022] By adopting the above technical solution, this application also adds an antioxidant during the SEBS modification process, which can inhibit the oxidation reaction during the modification process, reduce the generation of by-products, improve the yellowing resistance of modified SEBS scraps, and ultimately further improve the yellowing resistance of TPU composite film.

[0023] Optionally, the antioxidant is selected from pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] and dioctadecyl thiodipropionate in a mass ratio of 1:(0.5-0.7).

[0024] By adopting the above technical solution, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] is used as the main antioxidant and dioctadecyl thiodipropionate is used as the auxiliary antioxidant. The two work synergistically to inhibit the oxidation chain reaction and significantly improve the yellowing resistance of TPU composite film.

[0025] Optionally, the ultraviolet absorber is a benzophenone-based ultraviolet absorber, specifically UV-531; The light stabilizer is a hindered amine light stabilizer, specifically Tinuvin 770; The lubricant is calcium stearate, and the reinforcing filler is nano-silica or calcium carbonate. The adhesion promoter is a mixture of KH-550 and L-75 in a mass ratio of 1:(1-1.2).

[0026] By adopting the above technical solutions, silane coupling agents and isocyanate adhesive promoters can react with isocyanate groups in PU foam to form chemical bonds, significantly improving the interfacial adhesion strength between TPU composite film and PU foam. The addition of lubricant improves processing fluidity, and the addition of filler enhances mechanical strength.

[0027] Secondly, this application provides a method for preparing a TPU composite film for integral molding of shoe soles, using the following technical solution: A method for preparing a TPU composite film for one-piece molding of shoe soles includes the following steps: The raw materials are thoroughly mixed and then melt-blended and cast into a film to obtain a TPU composite film.

[0028] By adopting the above technical solution, the method provided in this application is simple, convenient, and easy to industrialize.

[0029] In summary, this application has the following beneficial effects: 1. The TPU composite film in this application is mainly composed of TPU particles, with modified SEBS scraps added as an auxiliary filler. SEBS is obtained by hydrogenating special linear SBS to saturate the double bonds. The carbon-carbon double bonds of the butadiene segment are hydrogenated and saturated, thus exhibiting good weather resistance, heat resistance, compression set resistance, and excellent mechanical properties, especially excellent aging resistance and yellowing resistance. Adding it as an auxiliary filler can improve the yellowing resistance of the TPU composite film. Combined with the effects of antioxidants, ultraviolet absorbers, and light stabilizers, the final TPU composite film has excellent yellowing resistance. 2. In this application, the polycarbonate diol in the heat-resistant modifier restricts the movement of molecular chains at high temperatures through hydrogen bonding between its rigid carbonate groups and the soft segments of TPU, thereby improving its heat resistance. The addition of graphene oxide-hydroxyl organosilicon modifier composite filler allows the two-dimensional sheet structure of graphene oxide to form a physical barrier, hindering heat conduction. Moreover, the oxygen-containing functional groups on the surface can form chemical bonds with TPU segments, enhancing thermal stability. Hydroxyl-terminated polydimethylsiloxane is a multifunctional organosilicon polymer with hydroxyl groups at both ends of its molecular chain, enabling it to react with TPU containing isocyanate groups to form a cross-linked structure. Furthermore, the silicon-oxygen bonds significantly improve its thermal stability. The addition of silane coupling agent allows graphene oxide to graft with hydroxyl-containing silane to form a three-dimensional network structure, improving its thermal barrier properties and ultimately significantly improving its heat resistance. Detailed Implementation

[0030] The following detailed description of this application is provided in conjunction with the embodiments. It should be noted that: unless otherwise specified, the conditions in the following embodiments are performed under conventional conditions or conditions recommended by the manufacturer. Unless otherwise specified, the raw materials used in the following embodiments are all from commercially available sources.

[0031] In the following preparation examples, the hydroxyl-terminated polydimethylsiloxane used is hydroxyl-terminated polydimethylsiloxane from Guangdong Wengjiang Chemical Reagent Co., Ltd.

[0032] SEBS scrap refers to the scraps obtained from cutting, repairing, and discarding SEBS materials during the production process.

[0033] The following preparation examples illustrate the preparation of graphene oxide-hydroxyl organosilicon modifier composite fillers. Preparation Example 1 A method for preparing a graphene oxide-hydroxyl organosilicon modifier composite filler includes the following steps: 1) Dissolve graphene oxide in 5 times its mass of water and then disperse it ultrasonically to obtain a graphene oxide solution. Then add an ethanol aqueous solution of silane coupling agent, mix and disperse to obtain a preliminary mixed solution. The amount of silane coupling agent added is 2 wt% of graphene oxide, and the amount of ethanol aqueous solution added is 3.5 times the mass of silane coupling agent. The ethanol aqueous solution is obtained by mixing ethanol and water at a volume ratio of 1:1.1. The silane coupling agents selected are aminosilane coupling agent KH-550 and epoxysilane coupling agent KH-560 with a mass ratio of 1:1. 2) Hydroxyl-terminated polydimethylsiloxane was dissolved in 1.5 times the mass of carbon tetrachloride to prepare an organosilicon solution. The mass ratio of hydroxyl-terminated polydimethylsiloxane to graphene oxide was 1:1.2. Then, the organosilicon solution was added to the initial mixture, the temperature was raised to 70℃, the pH was adjusted to 5, and the reaction was stirred for 2.5 h. After vacuum distillation, the mixture was dried under vacuum at 85℃ for 1.5 h, then heat-treated at 125℃ for 1.5 h, washed and dried to obtain the graphene oxide-hydroxy organosilicon modifier composite filler.

[0034] Preparation Example 2 A method for preparing a graphene oxide-hydroxyl organosilicon modifier composite filler includes the following steps: 1) Dissolve graphene oxide in 5 times its mass of water and then disperse it ultrasonically to obtain a graphene oxide solution. Then add an ethanol aqueous solution of silane coupling agent, mix and disperse to obtain a preliminary mixed solution. The amount of silane coupling agent added is 1 wt% of graphene oxide, the amount of ethanol aqueous solution added is 3 times the mass of silane coupling agent, and the ethanol aqueous solution is obtained by mixing ethanol and water in a volume ratio of 1:1. The silane coupling agents selected are aminosilane coupling agent KH-550 and epoxysilane coupling agent KH-560 with a mass ratio of 1:1. 2) Hydroxyl-terminated polydimethylsiloxane was dissolved in carbon tetrachloride at a mass ratio of 1 to obtain an organosilicon solution. The mass ratio of hydroxyl-terminated polydimethylsiloxane to graphene oxide was 1:1.2. Then, the organosilicon solution was added to the initial mixture, the temperature was raised to 60℃, the pH was adjusted to 4, and the reaction was stirred for 3 hours. After vacuum distillation, the mixture was dried under vacuum at 80℃ for 2 hours, then heat-treated at 120℃ for 2 hours, and finally washed and dried to obtain the graphene oxide-hydroxy organosilicon modifier composite filler.

[0035] Preparation Example 3 A method for preparing a graphene oxide-hydroxyl organosilicon modifier composite filler includes the following steps: 1) Dissolve graphene oxide in 6 times the mass of water and then disperse it by ultrasonication to obtain a graphene oxide solution. Then add an ethanol aqueous solution of silane coupling agent, mix and disperse to obtain a preliminary mixed solution. The amount of silane coupling agent added is 3 wt% of graphene oxide, and the amount of ethanol aqueous solution added is 4 times the mass of silane coupling agent. The ethanol aqueous solution is obtained by mixing ethanol and water at a volume ratio of 1:1.2. The silane coupling agents selected are aminosilane coupling agent KH-550 and epoxysilane coupling agent KH-560 with a mass ratio of 1:1. 2) Hydroxyl-terminated polydimethylsiloxane was dissolved in carbon tetrachloride at a mass ratio of 2 to obtain an organosilicon solution. The mass ratio of hydroxyl-terminated polydimethylsiloxane to graphene oxide was 1:1.3. Then, the organosilicon solution was added to the initial mixture, the temperature was raised to 80℃, the pH was adjusted to 6, and the reaction was stirred for 2 hours. After vacuum distillation, the mixture was dried under vacuum at 90℃ for 1 hour, then heat-treated at 130℃ for 1 hour, and finally washed and dried to obtain the graphene oxide-hydroxy organosilicon modifier composite filler.

[0036] Preparation Example 4 A method for preparing a graphene oxide-hydroxyl organosilicon modifier composite filler is carried out according to the method in Preparation Example 1, except that in step 1), after mixing and dispersing the ethanol aqueous solution with the addition of silane coupling agent, PAMAM is also added, and a preliminary mixture is obtained after dispersion, and the amount of PAMAM added is 4 wt% of the amount of graphene oxide added.

[0037] Preparation Example 5 A method for preparing a graphene oxide-hydroxyl organosilicon modifier composite filler is carried out according to the method in Preparation Example 1, except that in step 1), after mixing and dispersing the ethanol aqueous solution with the addition of silane coupling agent, PAMAM is also added, and a preliminary mixture is obtained after dispersion, and the amount of PAMAM added is 3wt% of the amount of graphene oxide added.

[0038] Preparation Example 6 A method for preparing a graphene oxide-hydroxyl organosilicon modifier composite filler is carried out according to the method in Preparation Example 1, except that in step 1), after mixing and dispersing the ethanol aqueous solution with the addition of silane coupling agent, PAMAM is also added, and a preliminary mixture is obtained after dispersion, and the amount of PAMAM added is 5 wt% of the amount of graphene oxide added.

[0039] Comparative Preparation Example 1 A method for preparing a graphene oxide-hydroxyl organosilicon modifier composite filler is carried out according to the method in Preparation Example 1. In step 1), no silane coupling agent is added to the ethanol aqueous solution, and the obtained graphene oxide solution is directly used as the initial mixture for subsequent step 2).

[0040] The TPU particles used in the following examples are aliphatic polyurethane TPUs from Dongguan Leishuo New Materials Co., Ltd., model L785A10, branded by BASF.

[0041] In the following examples, the ultraviolet absorber selected is a benzophenone-based ultraviolet absorber, specifically UV-531; The light stabilizer selected is a hindered amine light stabilizer, specifically Tinuvin 770. Example

[0042] A method for preparing a TPU composite film for one-piece molding of shoe soles includes the following steps: Raw material premix: Add 70kg TPU granules, 22kg SEBS scraps, 12kg heat-resistant modifier, 2kg antioxidant, 1kg UV absorber, 1kg light stabilizer, 1kg lubricant, 10kg reinforcing filler and 2kg adhesion promoter to a high-speed mixer and mix thoroughly to obtain a premix. Melt blending: The premixed material is added to a twin-screw extruder for melt blending, then extruded and granulated to obtain granules; Casting film formation: The granules are added to the casting machine, melted and extruded at 200°C, and cooled and shaped by a three-roll calender to obtain a TPU composite film with a thickness of 0.04 mm.

[0043] The heat-resistant modifier is a mixture of polycarbonate diol and graphene oxide-hydroxyl organosilicon modifier composite filler with a mass ratio of 1:1.6, and the graphene oxide-hydroxyl organosilicon modifier composite filler is the graphene oxide-hydroxyl organosilicon modifier composite filler prepared in Preparation Example 1. The adhesion promoter is a mixture of KH-550 and isocyanate L-75 in a mass ratio of 1:1.1; The lubricant is calcium stearate, the reinforcing filler is nano-silica, the light stabilizer is hindered amine light stabilizer, and the ultraviolet absorber is benzophenone-based ultraviolet absorber. Example

[0044] A method for preparing a TPU composite film for one-piece molding of shoe soles includes the following steps: Raw material premix: Add 60kg TPU granules, 15kg SEBS scraps, 8kg heat-resistant modifier, 1kg antioxidant, 0.5kg UV absorber, 0.5kg light stabilizer, 0.5kg lubricant, 5kg reinforcing filler and 1kg adhesion promoter to a high-speed mixer and mix thoroughly to obtain a premix. Melt blending: The premixed material is added to a twin-screw extruder for melt blending, then extruded and granulated to obtain granules; Casting film formation: The granules are added to the casting machine, melted and extruded at 190°C, and cooled and shaped by a three-roll calender to obtain a TPU composite film with a thickness of 0.03 mm.

[0045] The heat-resistant modifier is a mixture of polycarbonate diol and graphene oxide-hydroxyl organosilicon modifier composite filler with a mass ratio of 1:1.5, and the graphene oxide-hydroxyl organosilicon modifier composite filler is the graphene oxide-hydroxyl organosilicon modifier composite filler prepared in Preparation Example 2. The adhesion promoter is a mixture of KH-550 and isocyanate L-75 in a mass ratio of 1:1; The lubricant is calcium stearate, the reinforcing filler is nano-silica, the light stabilizer is hindered amine light stabilizer, and the ultraviolet absorber is benzophenone-based ultraviolet absorber. Example

[0046] A method for preparing a TPU composite film for one-piece molding of shoe soles includes the following steps: Raw material premix: Add 80kg TPU granules, 30kg SEBS scraps, 15kg heat-resistant modifier, 3kg antioxidant, 2kg UV absorber, 2kg light stabilizer, 2kg lubricant, 15kg reinforcing filler and 3kg adhesion promoter to a high-speed mixer and mix thoroughly to obtain a premix. Melt blending: The premixed material is added to a twin-screw extruder for melt blending, then extruded and granulated to obtain granules; Casting film formation: The granules are added to the casting machine, melted and extruded at 210°C, and cooled and shaped by a three-roll calender to obtain a TPU composite film with a thickness of 0.05 mm.

[0047] The heat-resistant modifier is a mixture of polycarbonate diol and graphene oxide-hydroxyl organosilicon modifier composite filler with a mass ratio of 1:1.8, and the graphene oxide-hydroxyl organosilicon modifier composite filler is the graphene oxide-hydroxyl organosilicon modifier composite filler prepared in Preparation Example 3. The adhesion promoter is a mixture of KH-550 and isocyanate L-75 in a mass ratio of 1:1.2; The lubricant is calcium stearate, the reinforcing filler is nano-silica, the light stabilizer is hindered amine light stabilizer, and the ultraviolet absorber is benzophenone-based ultraviolet absorber.

[0048] Examples 4-6 A method for preparing a TPU composite film for one-piece molding of shoe soles is carried out according to the method in Example 1, except that the graphene oxide-hydroxyl organosilicon modifier composite filler is selected from the graphene oxide-hydroxyl organosilicon modifier composite filler prepared in Examples 4-6. Example

[0049] A method for preparing a TPU composite film for one-piece molding of shoe soles, following the method in Example 1, except that SEBS scraps are added after modification. The specific steps are as follows: After cleaning and drying, SEBS scraps were added to toluene solvent at a concentration of 3.5 times their mass. The mixture was then heated to 100°C, and benzoyl peroxide and ethyl isocyanate were added dropwise. After reacting for 50 minutes, the temperature was raised to 120°C, and maleic anhydride was added dropwise. The mixture was stirred and reacted for 1.5 hours under nitrogen protection. The mixture was then added to ethanol to precipitate the precipitate. The precipitate was washed with ethanol and then with water. Finally, it was dried under vacuum to obtain modified SEBS scraps.

[0050] The initiator was added at 1 wt% of the SEBS scrap, and the mass ratio of ethyl isocyanate acrylate, maleic anhydride and SEBS scrap was 1:2.5:7. Example

[0051] A method for preparing a TPU composite film for one-piece molding of shoe soles, following the method in Example 1, except that SEBS scraps are added after modification. The specific steps are as follows: After cleaning and drying, SEBS scraps were added to toluene solvent at a concentration of 3 times their mass. The mixture was then heated to 90°C, and benzoyl peroxide and ethyl isocyanate were added dropwise. After reacting for 60 minutes, the temperature was raised to 110°C, and maleic anhydride was added dropwise. The mixture was stirred and reacted for 2 hours under nitrogen protection. The mixture was then added to ethanol to precipitate the precipitate. The precipitate was washed with ethanol and then with water. Finally, it was dried under vacuum to obtain modified SEBS scraps.

[0052] The initiator was added at 0.5 wt% of the SEBS scrap, and the mass ratio of ethyl isocyanate acrylate, maleic anhydride and SEBS scrap was 1:2:6. Example

[0053] A method for preparing a TPU composite film for one-piece molding of shoe soles, following the method in Example 1, except that SEBS scraps are added after modification. The specific steps are as follows: After cleaning and drying, SEBS scraps were added to toluene solvent at a mass ratio of 4. The mixture was then heated to 110°C. Benzoyl peroxide and ethyl isocyanate were added dropwise. After reacting for 40 minutes, the mixture was heated to 130°C and maleic anhydride was added dropwise. The mixture was stirred and reacted for 1 hour under nitrogen protection. The mixture was then added to ethanol to precipitate the precipitate. The precipitate was washed with ethanol and then with water. Finally, it was dried under vacuum to obtain modified SEBS scraps.

[0054] The initiator was added at 2 wt% of the SEBS scrap, and the mass ratio of ethyl isocyanate acrylate, maleic anhydride and SEBS scrap was 1:3:8. Example

[0055] A method for preparing a TPU composite film for one-piece molding of shoe soles is carried out according to the method in Example 7, except that ethyl isocyanate acrylate is not added during SEBS modification treatment. Example

[0056] A method for preparing a TPU composite film for one-piece molding of shoe soles is carried out according to the method in Example 7, except that before adding the initiator and ethyl isocyanate acrylate, hindered phenolic antioxidant 1010 is added first, and then the initiator and ethyl isocyanate acrylate are added, and the amount of hindered phenolic antioxidant added is 0.3 wt% of the amount of SEBS scrap added. Example

[0057] A method for preparing a TPU composite film for one-piece molding of shoe soles is carried out according to the method in Example 7, except that before adding the initiator and ethyl isocyanate acrylate, hindered phenolic antioxidant 1010 is added first, and then the initiator and ethyl isocyanate acrylate are added, and the amount of hindered phenolic antioxidant added is 0.1 wt% of the amount of SEBS scrap added. Example

[0058] A method for preparing a TPU composite film for one-piece molding of shoe soles is carried out according to the method in Example 7, except that before adding the initiator and ethyl isocyanate acrylate, hindered phenolic antioxidant 1010 is added first, and then the initiator and ethyl isocyanate acrylate are added, and the amount of hindered phenolic antioxidant added is 0.5 wt% of the amount of SEBS scrap added.

[0059] Comparative Example 1 A method for preparing a TPU composite film for one-piece molding of shoe soles is carried out according to the method in Example 1, except that the graphene oxide-hydroxyl organosilicon modifier composite filler is selected from the graphene oxide-hydroxyl organosilicon modifier composite filler in Comparative Preparation Example 1.

[0060] Comparative Example 2 A method for preparing a TPU composite film for one-piece molding of shoe soles is carried out according to the method in Example 1, except that the graphene oxide-hydroxyl organosilicon modifier is replaced in equal amounts with a mixture of graphene oxide and hydroxyl-terminated polydimethylsiloxane, and the mass ratio of hydroxyl-terminated polydimethylsiloxane to graphene oxide is 1:1.2.

[0061] Comparative Example 3 A method for preparing a TPU composite film for one-piece molding of shoe soles is carried out according to the method in Example 1, except that the heat-resistant modifier is selected from polycarbonate diol and graphene oxide in a mass ratio of 1:1.6.

[0062] Comparative Example 4 A method for preparing a TPU composite film for one-piece molding of shoe soles is carried out according to the method in Example 1, except that no heat-resistant modifier is added to the raw materials.

[0063] Comparative Example 5 A method for preparing a TPU composite film for one-piece molding of shoe soles is carried out according to the method in Example 1, except that SEBS scraps are not added to the raw materials.

[0064] Performance testing The TPU composite films prepared in the examples and comparative examples were tested for yellowing resistance according to HG / T 3689-2014 using SUNTEST (sun lamp method) and QUV (ultraviolet lamp method). The SUNTEST test conditions were as follows: (1) The sample surface was parallel to the bottom cut surface of the lamp and the distance was 250 mm; the sample tray rotation speed was 3 r / min; (2) The power of the sun lamp was 300 W, the wavelength of the ultraviolet light of the sun lamp was 280-400 nm and there was some visible light, and the intensity of the ultraviolet light of the sun lamp was 5 W / m. 2 Irradiate continuously at 50℃ for 24 hours.

[0065] The testing conditions for QUV (ultraviolet lamp method) were as follows: (1) Irradiation cycle temperature: 50℃ for UV irradiation; (2) Condensation cycle temperature: no condensation system; (3) Irradiance: 340nm; (4) Irradiance intensity: 0.89W / (m²·nm); (5) Irradiation duration: 24h; (6) Lamp type: UVA-340. After irradiation under the above conditions, the yellowing resistance level was assessed by comparing the color changes of the samples before and after the test using the gray scale card for assessing color fastness to textiles (GB / T 250-2008). The results are shown in Table 1 below.

[0066] In addition, the temperature resistance of the TPU composite films prepared in the examples and comparative examples was tested. Specifically, the shrinkage rate of the prepared TPU composite films with a size of 100*100mm was statistically analyzed after baking at 150°C for 2 hours. The statistical results are shown in Table 1 below.

[0067] Table 1:

[0068] By adopting the above technical solution, a yellowing resistance level greater than 3 is considered qualified. The higher the level, the better the yellowing resistance. The TPU film prepared in this application has excellent yellowing resistance and good heat resistance. Referring to the test results in Examples 1 and 4-6, when PAMAM was added during the preparation of the graphene oxide-hydroxyl organosilicon modifier composite filler in Examples 4-6, it not only helps graphene oxide and hydroxyl organosilicon to form a more stable composite structure, but also helps to improve its interaction with the TPU matrix, ultimately further improving both yellowing resistance and heat resistance. Combining the test results of Examples 7-9, it can be seen that the addition of modified SEBS scraps helps to improve the compatibility between SEBS and the TPU matrix, thereby better improving its yellowing resistance and heat resistance. Combining the test results of Example 10, when no isocyanate ethyl acrylate modifier was added during the SEBS modification treatment, its yellowing resistance and temperature resistance were reduced. The introduction of isocyanate groups in ethyl isocyanate ethyl acrylate further improves the interfacial bonding and compatibility between SEBS and the TPU matrix, thereby helping to enhance the yellowing resistance and temperature resistance of SEBS.

[0069] Referring to the test results of Examples 7 and 11-13, the addition of antioxidants during the SEBS modification process helps to inhibit the oxidation reaction during modification, thereby further improving the yellowing resistance. Combining the test results of Example 1 and Comparative Example 1, in the preparation of the graphene oxide-hydroxyl organosilicon modified composite filler in Comparative Example 1, the heat resistance was significantly reduced when hydroxyl organosilicon was directly added to the graphene oxide solution for modification. The addition of silane coupling agent can achieve good bonding between hydroxyl organosilicon and graphene oxide. The coating of graphene oxide by hydroxyl organosilicon can improve the aggregation phenomenon of graphene oxide and better improve the heat resistance. Combining the test results of Comparative Example 2, the heat resistance was significantly reduced when graphene oxide and hydroxyl organosilicon modifier were directly added in Comparative Example 2. The agglomeration of graphene oxide actually leads to a significant reduction in its performance. Combined with the test results of Comparative Example 3, the heat resistance of graphene oxide directly added to the heat-resistant modifier in Comparative Example 3 without modification or addition of hydroxyl organosilicon further reduced its heat resistance. The introduction of siloxane groups in hydroxyl organosilicon helps to further improve its heat resistance. Combined with the test results of Comparative Example 4, the heat resistance of the raw material was significantly reduced when no heat-resistant modifier was added. Combined with the test results of Comparative Example 5, the yellowing resistance and heat resistance were slightly reduced when SEBS scraps were not added to the raw material in Comparative Example 5.

[0070] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A TPU composite film for integral molding of shoe soles, characterized in that, Including the following parts by weight of raw materials: 60-80 parts TPU granules, 15-30 parts SEBS scraps, 1-3 parts antioxidant, 0.5-2 parts UV absorber, 0.5-2 parts light stabilizer, 0.5-2 parts lubricant, 5-15 parts reinforcing filler, 1-3 parts adhesion promoter and 8-15 parts heat-resistant modifier; The heat-resistant modifier is a mixture of polycarbonate diol and graphene oxide-hydroxyl organosilicon modifier composite filler. The graphene oxide-hydroxyl organosilicon modifier composite filler is prepared by adding hydroxyl-terminated polydimethylsiloxane to an ethanol aqueous solution containing silane coupling agent and graphene oxide, reacting and then drying.

2. The TPU composite film for integral molding of shoe soles according to claim 1, characterized in that: The graphene oxide-hydroxyl organosilicon modifier composite filler was prepared by the following method: Graphene oxide was dissolved in water and then ultrasonically dispersed to obtain a graphene oxide solution. Then, an ethanol aqueous solution of silane coupling agent was added, mixed and dispersed to obtain a preliminary mixture. Hydroxyl-terminated polydimethylsiloxane was dissolved in carbon tetrachloride to prepare an organosilicon solution. The organosilicon solution was then added to the initial mixture, heated to 60-80℃, and the pH was adjusted to 4-6. After stirring for 2-3 hours, the mixture was distilled under reduced pressure, dried under vacuum, and then heat-treated at 120-130℃ for 1-2 hours before washing and drying to obtain a graphene oxide-hydroxyl organosilicon modifier composite filler.

3. The TPU composite film for integral molding of shoe soles according to claim 2, characterized in that: In the preparation of graphene oxide-hydroxyl organosilicon modifier composite filler, the amount of silane coupling agent added is 1-3 wt% of graphene oxide, the mass ratio of graphene oxide to water is 1:(5-6), and the amount of ethanol aqueous solution added is 3-4 times the mass of silane coupling agent. The ethanol aqueous solution is obtained by mixing ethanol and water at a volume ratio of 1:(1-1.2). The mass ratio of hydroxyl-terminated polydimethylsiloxane to graphene oxide is 1:(1.2-1.3), and the hydroxyl-terminated polydimethylsiloxane is dissolved in 1-2 times the mass of carbon tetrachloride.

4. The TPU composite film for integral molding of shoe soles according to claim 2, characterized in that: In the preparation of graphene oxide-hydroxyl organosilicon modifier composite filler, after mixing and dispersing the ethanol aqueous solution with silane coupling agent, PAMAM is also added. After dispersion, a preliminary mixture is obtained, and the amount of PAMAM added is 3-5 wt% of the amount of graphene oxide added.

5. The TPU composite film for integral molding of shoe soles according to claim 1, characterized in that: The SEBS scraps were added after modification treatment, and the specific operation was as follows: After cleaning and drying SEBS scraps, they are added to toluene solvent. The temperature is then raised to 90-110℃, and an initiator and ethyl isocyanate acrylate are added dropwise. After reacting for 40-60 minutes, the temperature is raised to 110-130℃, and maleic anhydride is added dropwise. The mixture is stirred and reacted for 1-2 hours under nitrogen protection. Then, the mixture is added to ethanol to precipitate the precipitate. The precipitate is then washed with ethanol and dried under vacuum to obtain modified SEBS scraps.

6. The TPU composite film for integral molding of shoe soles according to claim 5, characterized in that: When preparing modified SEBS scrap, the mass ratio of SEBS scrap to toluene solvent is 1:(3-4), the amount of initiator added is 0.5-2wt% of SEBS scrap, and the mass ratio of ethyl isocyanate acrylate, maleic anhydride and SEBS scrap is 1:(2-3):(6-8).

7. The TPU composite film for integral molding of shoe soles according to claim 5, characterized in that: In the preparation of modified SEBS scrap, before adding the initiator and ethyl isocyanate acrylate, a hindered phenolic antioxidant is added first, and the amount of hindered phenolic antioxidant added is 0.1-0.5 wt% of the amount of SEBS scrap added.

8. The TPU composite film for integral molding of shoe soles according to claim 1, characterized in that: The ultraviolet absorber is selected from benzophenone-based ultraviolet absorbers; The light stabilizer is selected from hindered amine light stabilizers; The lubricant is calcium stearate, and the reinforcing filler is nano-silica or calcium carbonate.

9. The TPU composite film for integral molding of shoe soles according to claim 1, characterized in that: The adhesion promoter is a mixture of KH-550 and L-75 in a mass ratio of 1:(1-1.2).

10. A method for preparing a TPU composite film for integral molding of shoe soles as described in any one of claims 1-9, characterized in that: Includes the following steps: The raw materials are thoroughly mixed and then melt-blended and cast into a film to obtain a TPU composite film.

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