Shoe material master batch based on coffee grounds and preparation method thereof

Abstract

The invention provides a shoe material master batch based on coffee grounds and a preparation method thereof. The shoe material master batch comprises the following raw materials in parts by mass: 100 parts of coffee grounds, 30-70 parts of a thermoplastic material, 5-10 parts of an isocyanate-terminated polyurethane prepolymer, 3-10 parts of a compatibilizer, 1-5 parts of a filler and 0.1-1 part of an antioxidant. The content of the coffee grounds in the shoe material master batch is 50% or above, the isocyanate-terminated polyurethane prepolymer is applied to the highly-doped coffee grounds system, the interface bonding force between the coffee grounds and a thermoplastic material matrix and the melt supporting capacity can be remarkably improved through the cooperation of the isocyanate-terminated polyurethane prepolymer and the filler, the shoe material master batch has the good melt index and melt strength, and the service life of the shoe material master batch is prolonged. The foaming material has good processability and foaming performance, so that the foaming material can be better applied to foaming shoe materials.

Description

Technical Field

[0001] This application relates to the technical field of polymer materials, and specifically relates to a shoe material masterbatch based on coffee grounds and a preparation method thereof. Background Art

[0002] Shoe materials are widely used in daily life, sports and leisure, and professional functional fields. Their core structures are mostly composed of foamed polymer materials, which have the advantages of light weight, good elasticity, and shock absorption. At present, commercially available foamed shoe materials are generally based on ethylene-vinyl acetate copolymer (EVA) and are prepared by closed mold hot pressing or injection foaming processes. The EVA material itself has good foaming properties and flexibility, but it mainly relies on petroleum-based resources, has high carbon emissions, and the resources are non-renewable, making it difficult to meet the requirements of green and sustainable development.

[0003] To reduce the dependence on petroleum-based materials and improve the environmental friendliness of materials, more and more research focuses on the composite technology of biomass fillers and polymer matrices. Among them, coffee grounds, as a kind of natural organic waste with large output, low cost, and recyclability, have received extensive attention. Coffee grounds contain various organic functional groups and fine porous structures, and theoretically have good nucleation potential and interfacial reaction activity. However, in practical applications, the coffee ground particles have strong surface polarity, irregular particle sizes, are prone to agglomeration, and have poor compatibility with hydrophobic thermoplastic polymers, resulting in an increase in the melt viscosity of the composite material, difficult processing, and unstable foaming ratio.

[0004] At present, there have been reports on the application of coffee grounds as fillers in shoe materials. For example, patent CN117362774A discloses a rapidly degradable foaming material for shoe soles. According to mass parts, the material includes the following raw materials: 85-105 parts of natural rubber, 25-45 parts of coffee grounds, 10-20 parts of betel nut fiber, 6-15 parts of red clay, 3-8 parts of silane coupling agent, 0.5-3 parts of vulcanizing agent, 0.5-5 parts of accelerator, 0.1-3 parts of antioxidant, 2-6 parts of foaming agent, and 1-10 parts of auxiliary agent. This foaming material has good degradable properties.

[0005] The above patent uses natural rubber as the main material, and through corona treatment of coffee grounds and betel nut fiber and cooperation with silane coupling agent, it has good compatibility with natural rubber. However, the doping amount of the above biomass fillers is relatively low. In the case of using coffee grounds at a high doping amount (more than 50%), it is difficult to overcome the influence of coffee grounds on the material properties only by improving its compatibility, which severely limits the popularization and application of coffee grounds in high-performance foamed shoe materials.

[0006] Therefore, there is an urgent need to propose a high-doping coffee ground masterbatch system with reasonable structure, stable performance, and suitable for foamed shoe materials, while ensuring the high utilization rate of coffee grounds and expanding its application prospects in green foamed shoe materials. Summary of the Invention

[0007] The present application provides a shoe material masterbatch based on coffee grounds and a preparation method thereof. The coffee ground content of the shoe material masterbatch is more than 50%. By optimizing the formula, the coffee grounds and the thermoplastic material matrix have good interfacial bonding force and melt support ability, and the problems of insufficient melt strength and unstable interface in the high-doping system are improved.

[0008] In the first aspect, the present application provides a shoe material masterbatch based on coffee grounds, which comprises the following raw materials in parts by mass: 100 parts of coffee grounds, 30-70 parts of thermoplastic materials, 5-10 parts of isocyanate-terminated polyurethane prepolymer, 3-10 parts of compatibilizer, 1-5 parts of filler, and 0.1-1 part of antioxidant.

[0009] Based on the present application, the coffee ground content in the shoe material masterbatch is more than 50%. By applying the isocyanate-terminated polyurethane prepolymer (TPU prepolymer) to this high-doped coffee ground system, the terminal isocyanate groups of the TPU prepolymer can react with the hydroxyl groups on the surface of the coffee grounds to form strong urethane bonds. Moreover, the flexible chain segments (polyether polyol or polyester polyol chain segments) of the TPU prepolymer can also form a physical entanglement network at the microscopic level with the thermoplastic material matrix. The rigid filler can be filled in the entanglement network, thereby significantly improving the interfacial bonding force and melt support ability between the coffee grounds and the thermoplastic material matrix, making the shoe material masterbatch have better melt index and melt strength, good processing performance and foaming performance, and thus being better applied to foamed shoe materials.

[0010] Specifically, the inventors found that in a shoe material masterbatch system with a high doping amount, due to the coffee grounds interrupting the continuity of the polymer chains, being prone to agglomeration, and having a weak interfacial bonding force with the thermoplastic material, while the high doping amount restricts the degree of freedom of movement of the polymer chain segments, the melt index and melt strength of the shoe material masterbatch will be significantly reduced, seriously affecting the processing performance and foaming performance of the shoe material masterbatch; in the related art, only a compatibilizer is added to improve the compatibility between the coffee grounds and the thermoplastic material matrix. Although the melt index of the shoe material masterbatch can be improved to a certain extent, the influence of the high-doping coffee grounds on the melt strength of the masterbatch cannot be improved. When the melt strength is low, the melt structure support force of the masterbatch is insufficient, and the cell walls are prone to collapse and rupture during the foaming process, resulting in uneven cell structure or even foaming failure, thus seriously restricting the application of the high-doping shoe material masterbatch in foamed shoes. Based on this, in the high-doping system, in addition to adding a compatibilizer, the inventors also added a polyurethane prepolymer capped with isocyanate and a filler. The end groups of the polyurethane prepolymer are active isocyanate groups, and during the melt blending process, the isocyanate groups can react with the hydroxyl groups on the surface of the coffee grounds to form urethane bonds. At the same time, the flexible chain segments on the polyurethane prepolymer have good compatibility with the thermoplastic material matrix, so that a strong and stable interfacial anchoring is formed at the interface between the coffee grounds and the thermoplastic material, which can effectively reduce the influence of the high-doping coffee grounds on the melt index and melt strength of the masterbatch; on the other hand, the flexible chain segments of the polyurethane prepolymer can entangle with the polymer chain segments of the thermoplastic material to form a physical entanglement network (the entanglement network refers to the physical entanglement or local chain intercalation phenomenon that occurs between polymer chain segments due to sufficient molecular length and moderate flexibility in the molten state). At the same time, the entanglement network can embed the coffee ground particles anchored by the TPU prepolymer into the flexible network. The coffee grounds with a certain rigidity can further support the entanglement network. A filler is also added to the masterbatch system. Under the action of the compatibilizer, the filler is more easily dispersed and embedded in the entanglement network, and cooperates with the coffee grounds to form a physical support framework in the melt, enhancing the melt strength of the shoe material masterbatch.

[0011] In addition, it can be understood that the coffee grounds and the filler in the masterbatch can serve as cell nucleation sites during the subsequent foaming process. By being evenly distributed in the system, the coffee grounds and the filler can promote the uniform distribution of the cells and increase the cell density. Therefore, the thermoplastic material in the masterbatch can select materials such as polyethylene with poor self-foaming performance instead of EVA materials. The polyethylene material can be selected from bio-based polyethylene, which can further increase the biochar content of the masterbatch, reduce the demand for fossil energy, and meet the requirements of composite green environmental protection.

[0012] The shoe material masterbatch provided by the present application can have good melt index and melt strength under the condition of high-doping coffee grounds by optimizing the components and their contents, thus having good processing performance and foaming performance, and can be better applied to green foamed shoes.

[0013] It should be noted that the "melt index" and "melt strength" of the materials in this application have meanings well-known in the art. The "melt index" can represent the flow rate of the material under specific temperature and load (unit: g / 10min). In this application, unless otherwise specified, the tests are carried out under the conditions of 190°C / 2.16 kg; the "melt strength" can represent the maximum tensile force or tension that the material melt can withstand during the stretching process (unit: mN). In this application, unless otherwise specified, the "melt strength" is tested under the conditions of 170°C and a stretching speed of 10 mm / s.

[0014] In some embodiments, the isocyanate-terminated polyurethane prepolymer is obtained by reacting the following raw materials in parts by mass: 60 parts of polyether polyol, 30 - 50 parts of polyester polyol, and 20 - 60 parts of polyisocyanate.

[0015] In the above-mentioned some embodiments, the inventors found that when the isocyanate-terminated polyurethane prepolymer is prepared from the above-mentioned parts by mass of polyether polyol, polyester polyol, and polyisocyanate, the melt strength of the shoe material masterbatch is higher. The possible reason is that the polyurethane prepolymer obtained at this time includes polyether polyol and polyester polyol segments. The polyether polyol segment has better flexibility than the polyester polyol segment and is more likely to entangle with the polymer segments of the thermoplastic material matrix to form an entanglement network. The polyester polyol segment has better strength than the polyether polyol segment, and the formed entanglement network has a greater improvement on the melt strength of the masterbatch. The polyurethane prepolymer obtained through a suitable monomer ratio can improve the toughness of the entanglement network while forming a stable entanglement network, thereby obtaining a shoe material masterbatch with higher melt strength and better foaming performance.

[0016] It should be noted that polyisocyanate has a meaning well-known in the art, that is, it refers to an isocyanate containing two or more active isocyanate groups, including but not limited to diisocyanate and triisocyanate.

[0017] In some embodiments, the polyether polyol may include at least one of PTMG-1000 (polytetrahydrofuran-1000), PTMG-1400, polyether 210, polyether 220, and polyether 330; the polyester polyol may include at least one of PBA-1000 (polybutylene adipate diol-1000), PBA-2000, PCL-1000 (polycaprolactone diol-1000), and PCL-2000. As an example, in an embodiment of the present application, the polyether polyol is PTMG-1000 and the polyester polyol is PCL-1000.

[0018] In some embodiments, the polyisocyanate includes diisocyanate, and the diisocyanate includes aromatic diisocyanate.

[0019] In some of the above embodiments, the melt strength of the shoe material masterbatch obtained by using aromatic diisocyanate is higher. The reaction activity and structural rigidity of aromatic diisocyanate are higher than those of aliphatic diisocyanate, and it is easier to react with the surface of coffee grounds to form a strong and stable interfacial structure, providing stronger structural support for the entanglement network, resulting in higher melt strength and better foaming performance of the shoe material masterbatch.

[0020] It can be understood that aromatic diisocyanate has the meaning well-known in the art, that is, an isocyanate that includes an aromatic group and has two active isocyanate groups.

[0021] In some embodiments, the aromatic diisocyanate includes at least one of MDI (diphenylmethane diisocyanate) and TDI (toluene diisocyanate). As an example, in one embodiment of the present application, the aromatic diisocyanate is 2,4-TDI (toluene-2,4-diisocyanate).

[0022] In some embodiments, the polyisocyanate further includes a triisocyanate, and the mass percentage content of the triisocyanate in the polyisocyanate is 5% - 15%.

[0023] In some of the above embodiments, the inventors found that during the preparation of the polyurethane prepolymer, further introducing an appropriate amount of triisocyanate and using it together with the diisocyanate to prepare the polyurethane prepolymer results in higher melt strength of the shoe material masterbatch. The reason may be that the polyurethane prepolymer obtained by generally using only diisocyanate is a linear thermoplastic polyurethane, while using triisocyanate easily produces strong crosslinking to form a polyurethane network, and the processing performance will be significantly reduced. In the above technical solution, by using diisocyanate as the main body and slightly incorporating triisocyanate as a reactive chain extender, a slightly branched or star-shaped polyurethane prepolymer can be obtained, keeping the polyurethane prepolymer within the processable range. Through appropriate local crosslinking and interpenetration with the polymer segments of the thermoplastic material, the support strength of the formed entanglement network is higher, further improving the melt strength of the shoe material masterbatch and having better foaming performance. As an example, in one embodiment of the present application, the triisocyanate is triphenylmethane triisocyanate.

[0024] In some embodiments, the method for preparing the isocyanate-terminated polyurethane prepolymer includes: first reacting polyether polyol, polyester polyol with diisocyanate, and then adding triisocyanate to react to obtain the isocyanate-terminated polyurethane prepolymer.

[0025] In some of the above embodiments, the polyurethane prepolymer obtained by the above preparation method can endow the shoe material masterbatch with better processability and foaming performance. The reason may be that since the reactivity of the ternary isocyanate is higher than that of the binary isocyanate, if polyether polyol and polyester polyol are added to the reaction system simultaneously and react and crosslink prior to the ternary isocyanate, it may lead to uneven crosslinking of the polyurethane prepolymer and too high local crosslinking density, resulting in a decrease in the processability of the polyurethane prepolymer, uneven dispersion in the masterbatch system, and too high crosslinking density will also affect the interpenetration of the polymer segments of the thermoplastic material in the masterbatch. Adding the binary isocyanate and the ternary isocyanate in segments can enable the binary isocyanate to react with the polyether polyol and polyester polyol first to form linear segments, and then adding the ternary isocyanate as a crosslinking site to react with the linear segments, making the crosslinking more controllable and more likely to form a slightly branched or star-shaped structure of the polyurethane prepolymer, resulting in a higher support strength of the entanglement network, a higher melt strength of the masterbatch, better foaming performance, and not significantly deteriorating its processing performance.

[0026] In some embodiments, the filler has a through-hole structure, and the average particle size of the filler is 0.1 - 3 μm, and the average pore diameter is 2 - 15 nm.

[0027] In some of the above ways, when using a filler with the above particle size, pore diameter and containing a through-hole structure, while the filler has good rigidity, the through-hole structure has better cell nucleation ability, and the through-hole structure can serve as a gas storage nucleus and a cell skeleton. The larger specific surface area also enables the entanglement and adsorption of the flexible chain segments and the polymer segments of the thermoplastic material in the polyurethane prepolymer, making it easier to form a stable physical support network, with a stronger support effect on the entanglement network, thereby synergistically enabling the polyurethane prepolymer to further improve the melt strength of the shoe material masterbatch, and can make the uniformity and stability of the cells formed by foaming better, having better foaming performance. As an example, in an embodiment of the present application, the filler is SBA-15 with an average particle size of 1 μm and an average pore diameter of 12 nm.

[0028] In some embodiments, the water content of the coffee grounds is less than 1 wt%, and the particle size is not greater than 100 mesh. Based on the above embodiments, coffee grounds with a lower water content and a smaller particle size are more conducive to dispersion in the masterbatch system, resulting in better processability and foaming performance of the masterbatch.

[0029] In some embodiments, the thermoplastic material includes at least one of polyethylene, ethylene-vinyl acetate copolymer, and natural rubber. Based on the above embodiments, the shoe material masterbatch obtained by using the above different thermoplastic materials all has good processability and foaming performance.

[0030] In some embodiments, the compatibilizer includes at least one of EVA-g-MAH (maleic anhydride grafted ethylene-vinyl acetate copolymer), PE-g-MA (maleic anhydride grafted polyethylene), and POE-g-GMA (glycidyl methacrylate grafted polyolefin elastomer). Based on the above embodiments, the above compatibilizer can effectively synergize with the polyurethane prepolymer to disperse coffee grounds and fillers, reduce the influence of coffee grounds and fillers on the processing performance of the masterbatch, and endow the masterbatch with good processability and foaming performance. As an example, in an embodiment of the present application, POE-g-GMA with the trade name W5D is used as the compatibilizer.

[0031] In some embodiments, the antioxidant includes at least one of antioxidant 1010, antioxidant 1076, and antioxidant 264. Based on the above embodiments, the use of antioxidants can reduce the oxidation of the masterbatch by oxygen and improve the storage and service life of the masterbatch. As an example, in an embodiment of the present application, antioxidant 1010 is used as the antioxidant.

[0032] In some embodiments, the thermoplastic material is polyethylene with a melt index of 2-3 g / 10 min; the melt strength of the shoe material masterbatch is not less than 220 mN.

[0033] In the above-mentioned some embodiments, using polyethylene with a melt index of 2-3 g / 10 min as the thermoplastic material can endow the shoe material masterbatch with good melt flow performance while ensuring its melt strength and cell structure supportability. The melt strength of the shoe material masterbatch is not less than 220 mN, and it has good foaming performance. As an example, in an embodiment of the present application, polyethylene with a melt index of 2.8 g / 10 min is used as the thermoplastic material.

[0034] In a second aspect, the present application provides a method for preparing a coffee ground-based shoe material masterbatch, including: Providing the raw materials of the shoe material masterbatch according to any one of the embodiments of the first aspect; Mixing the raw materials and then performing melt co-extrusion and cooling pelletization to obtain the shoe material masterbatch.

[0035] According to the present application, this method can prepare the shoe material masterbatch of the first aspect. The content of coffee grounds in the shoe material masterbatch is more than 50%, and it has good melt index and melt strength, and can be used to prepare green and environmentally friendly foamed shoe materials.

[0036] In some embodiments, the raw materials are dried and then mixed and melt co-extruded.

[0037] In some embodiments, the conditions for melt co - extrusion include: using a twin - screw extruder for melt extrusion, the temperatures of each zone of the twin - screw extruder are 130 - 140 °C, 150 - 160 °C, 150 - 160 °C, 165 - 175 °C, 170 - 175 °C, 160 - 170 °C respectively, and the screw speed is 100 - 300 r / min.

[0038] In a third aspect, the present application provides a foamed shoe material, which includes the shoe material masterbatch according to any one of the embodiments of the first aspect or the shoe material masterbatch prepared by the method according to any one of the embodiments of the second aspect.

[0039] According to the present application, the foamed shoe material includes the shoe material masterbatch according to any one of the embodiments of the first aspect or the shoe material masterbatch prepared by the method according to any one of the embodiments of the second aspect. This shoe material masterbatch has good foaming properties, and a foamed shoe material with good cell structure can be obtained; moreover, the content of bio - charcoal in the foamed shoe material is high, meeting the requirements of composite green environmental protection chemistry.

[0040] Compared with the prior art, the beneficial effects of the present application are at least as follows: By optimizing the components and their contents in the shoe material masterbatch system, under the condition of high - doped coffee grounds, it has good melt index and melt strength, thus having good processing performance and foaming performance, and can be better applied to green foamed shoe materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 is a physical picture of a coffee - ground - based shoe material masterbatch prepared in an embodiment of the present application.

[0042] Figure 2 is a physical picture of a foamed board prepared by foaming the coffee - ground - based shoe material masterbatch prepared in an embodiment of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0043] The embodiments or implementation schemes in this specification are described in a progressive manner. The key points of each embodiment are the differences from other embodiments.

[0044] In the description of this specification, the description of reference terms such as "an embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" etc. means that the specific features, structures, materials or characteristics described in connection with the embodiments or examples are included in at least one embodiment or example of the present application. In this specification, the schematic expressions of the above - mentioned terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0045] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In the description of this application, the meaning of "a plurality" is at least two, such as two, three, etc., unless otherwise specifically defined.

[0046] In the description of this specification, unless otherwise specified, "parts" refers to "parts by mass".

[0047] Hereinafter, embodiments of this application will be described. The embodiments described below are exemplary and are only used to explain this application and should not be construed as limiting this application. For those technical or conditions not specified in the embodiments, they shall be carried out according to the technologies or conditions described in the literature in this field or according to the product specifications. For the reagents or instruments whose manufacturers are not indicated, they are all conventional products that can be obtained through commercial purchase.

[0048] Coffee grounds, recovered from various coffee shops in Wuhan, were ground and dried until the moisture content was below 1 wt%, and then passed through a 150-mesh sieve for standby.

[0049] SBA-15, with an average particle size of 1 μm and an average pore diameter of 12 nm.

[0050] Silica particles, with an average particle size of 1 μm.

[0051] Preparation Example 1 Preparation of isocyanate-terminated polyurethane prepolymer: 60 parts of PTMG-1000 and 40 parts of PCL-1000 were added to a reactor, dehydrated under vacuum at 105 °C for 1 h, cooled to 80 °C, 31.35 parts of 2,4-TDI were added to the reactor, and after stirring and reacting for 1.5 h, it was cooled to 70 °C, then 3.67 parts of triphenylmethane triisocyanate were added, and after stirring and reacting for 0.5 h, an isocyanate-terminated polyurethane prepolymer was obtained, denoted as TPU-1.

[0052] Preparation Example 2 Preparation of isocyanate-terminated polyurethane prepolymer: 100 parts of PTMG-1000 were added to a reactor, dehydrated under vacuum at 105 °C for 1 h, cooled to 80 °C, 31.35 parts of 2,4-TDI were added to the reactor, and after stirring and reacting for 1.5 h, it was cooled to 70 °C, then 3.67 parts of triphenylmethane triisocyanate were added, and after stirring and reacting for 0.5 h, an isocyanate-terminated polyurethane prepolymer was obtained, denoted as TPU-2.

[0053] Preparation Example 3 Preparation of isocyanate-terminated polyurethane prepolymer: Add 100 parts of PCL-1000 into the reactor, dehydrate under vacuum at 105°C for 1 h, cool down to 80°C, add 31.35 parts of 2,4-TDI into the reactor, stir and react for 1.5 h, then cool down to 70°C, add 3.67 parts of triphenylmethane triisocyanate, stir and react for 0.5 h to obtain an isocyanate-terminated polyurethane prepolymer, denoted as TPU-3.

[0054] Preparation Example 4 Preparation of isocyanate-terminated polyurethane prepolymer: Add 60 parts of PTMG-1000 and 40 parts of PCL-1000 into the reactor, dehydrate under vacuum at 105°C for 1 h, cool down to 80°C, add 32.41 parts of 2,4-TDI (the total molar amount of isocyanate groups is the same as that in Preparation Example 1) into the reactor, stir and react for 2 h to obtain an isocyanate-terminated polyurethane prepolymer, denoted as TPU-4.

[0055] Preparation Example 5 Preparation of isocyanate-terminated polyurethane prepolymer: Add 60 parts of PTMG-1000 and 40 parts of PCL-1000 into the reactor, dehydrate under vacuum at 105°C for 1 h, cool down to 80°C, add 31.35 parts of 2,4-TDI and 3.67 parts of triphenylmethane triisocyanate into the reactor, stir and react for 2 h to obtain an isocyanate-terminated polyurethane prepolymer, denoted as TPU-5.

[0056] Example 1

[0057] Preparation of coffee grounds-based shoe material masterbatch: Premix 100 parts of coffee grounds, 50 parts of polyethylene material with a melt index of 2.8 g / 10 min, 7 parts of POE-g-GMA, 3 parts of SBA-15, and 0.5 part of antioxidant 1010 in a high-speed mixer, then add 8 parts of TPU-1 to obtain a mixture. Melt-blend and extrude the mixture in a twin-screw extruder, and cool and pelletize to obtain a coffee grounds-based shoe material masterbatch; The temperatures of each zone of the twin-screw extruder are 135°C, 155°C, 155°C, 170°C, 170°C, and 165°C respectively, and the screw speed is 200 r / min.

[0058] The physical picture of the obtained coffee grounds-based shoe material masterbatch is as Figure 1 shown.

[0059] Example 2

[0060] Preparation of coffee grounds-based shoe material masterbatch: It is substantially the same as Example 1, except that TPU-2 is used instead of TPU-1.

[0061] Example 3

[0062] Preparation of coffee grounds-based masterbatch for shoe materials: It is substantially the same as Example 1, except that TPU-3 is used instead of TPU-1.

[0063] Example 4

[0064] Preparation of coffee grounds-based masterbatch for shoe materials: It is substantially the same as Example 1, except that TPU-4 is used instead of TPU-1.

[0065] Example 5

[0066] Preparation of coffee grounds-based masterbatch for shoe materials: It is substantially the same as Example 1, except that TPU-5 is used instead of TPU-1.

[0067] Example 6

[0068] Preparation of coffee grounds-based masterbatch for shoe materials: It is substantially the same as Example 1, except that silica particles are used instead of SBA-15.

[0069] Comparative Example 1 Preparation of coffee grounds-based masterbatch for shoe materials: 100 parts of coffee grounds, 50 parts of polyethylene material with a melt index of 2.8 g / 10 min, 15 parts of POE-g-GMA, 3 parts of SBA-15, and 0.5 part of antioxidant 1010 are premixed in a high-speed mixer to obtain a mixture. The mixture is melt-blended and extruded in a twin-screw extruder, and then cooled and pelletized to obtain a coffee grounds-based masterbatch for shoe materials; Among them, the temperatures of each zone of the twin-screw extruder are 135 °C, 155 °C, 155 °C, 170 °C, 170 °C, and 165 °C respectively, and the screw speed is 200 r / min.

[0070] Comparative Example 2 Preparation of coffee grounds-based masterbatch for shoe materials: 103 parts of coffee grounds, 50 parts of polyethylene material with a melt index of 2.8 g / 10 min, 7 parts of POE-g-GMA, and 0.5 part of antioxidant 1010 are premixed in a high-speed mixer, and then 8 parts of TPU-1 are added and mixed to obtain a mixture. The mixture is melt-blended and extruded in a twin-screw extruder, and then cooled and pelletized to obtain a coffee grounds-based masterbatch for shoe materials; Among them, the temperatures of each zone of the twin-screw extruder are 135 °C, 155 °C, 155 °C, 170 °C, 170 °C, and 165 °C respectively, and the screw speed is 200 r / min.

[0071] Test section The melt index of the shoe material masterbatch obtained by testing each example and comparative example using a melt flow rate tester (conditions: 190 °C / 2.16 kg); the melt strength of the shoe material masterbatch obtained by testing each example and comparative example using a melt tensile rheometer (conditions: 170 °C, 10 mm / s), and the results are shown in Table 1; Foaming performance test: 80 parts of the shoe material masterbatch to be tested, 20 parts of EVA (VA content is 28%) and 3 parts of AC blowing agent were mixed evenly at 120 °C in an open internal mixer to obtain a mixture. Using the closed mold hot pressing foaming method, the mold was preheated at 175 °C for 5 min, the mixture to be tested was added into the mold cavity, the mold was closed and pressurized to 6 MPa, and the pressure was maintained for foaming for 10 min. After the foaming was completed, the temperature was lowered to below 60 °C in the mold, the foamed material was removed, and the structure was stabilized at room temperature for 24 h to obtain the sample to be tested; referring to GB / T 6670-2008 "Determination of rebound resilience of flexible cellular polymeric materials - Ball indentation method", the rebound rate of the sample to be tested was measured, and the results are shown in Table 1. The physical diagram of the foamed board obtained by foaming in Example 1 is as Figure 2 shown.

[0072] Table 1

[0073] As can be seen from Table 1, the melt index of the shoe material masterbatch obtained in each example is above 1.6 g / 10 min, having good processing performance, and the melt strength and rebound rate are significantly improved compared with each comparative example, and the melt strength is above 240 mN, indicating that the shoe material masterbatch provided by the present application has high melt strength and foaming performance, and can be a masterbatch with a high doping amount for preparing green and environmentally friendly foamed shoe materials. The reason may be that in Comparative Example 1, polyurethane prepolymer was not used, and only a compatibilizer was used to increase the compatibility between coffee grounds and the thermoplastic material matrix. However, the interfacial binding force between the compatibilizer and coffee grounds is weak, and it cannot effectively reduce the influence of coffee grounds on the melt strength of the masterbatch, resulting in low melt strength, poor foaming performance, and low rebound rate of the obtained foamed material, which is not suitable for preparing green and environmentally friendly foamed shoe materials; in Comparative Example 2, no filler was added. Although using polyurethane prepolymer can form an entanglement network with the polymer segments of the thermoplastic material, and coffee grounds can support the strength of the entanglement network to a certain extent, the particle size of coffee grounds is relatively large, and the supporting effect is limited, resulting in relatively low melt strength. In addition, due to the lack of cell nucleation points formed by the filler, the rebound rate of the obtained foamed material is also relatively low.

[0074] As can be seen from Examples 1 to 3, the composition of the flexible chain segment in the polyurethane prepolymer has a certain influence on the melt strength and foaming performance of the shoe material masterbatch. The polyurethane prepolymer prepared by using polyether polyol and polyester polyol as flexible chain segments in a certain mass ratio can further improve the melt strength and foaming performance of the shoe material masterbatch.

[0075] According to Examples 1 and 4, it can be seen that the selection of polyisocyanate in the raw materials for preparing polyurethane prepolymer has a certain influence on the melt strength and foaming properties of the shoe material masterbatch. The polyurethane prepolymer prepared by using a binary isocyanate and a ternary isocyanate in a certain mass ratio can further improve the melt strength and foaming properties of the shoe material masterbatch.

[0076] According to Examples 1 and 5, it can be seen that the addition sequence of the binary isocyanate and the ternary isocyanate during the preparation of the polyurethane prepolymer also affects the melt strength and foaming properties of the shoe material masterbatch. Adding the binary isocyanate first and then adding an appropriate amount of the ternary isocyanate after the reaction, the obtained polyurethane prepolymer can further improve the melt strength and foaming properties of the shoe material masterbatch.

[0077] According to Examples 1 and 6, it can be seen that the structure of the filler has a certain influence on the melt index, melt strength and foaming properties of the shoe material masterbatch. Using a filler with a through-hole structure can further improve the melt index, melt strength and foaming properties of the shoe material masterbatch.

[0078] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A shoe material masterbatch based on coffee grounds, characterized in that, Comprising the following raw materials in parts by mass: 100 parts of coffee grounds, 30 - 70 parts of thermoplastic material, 5 - 10 parts of isocyanate-terminated polyurethane prepolymer, 3 - 10 parts of compatibilizer, 1 - 5 parts of filler, 0.1 - 1 part of antioxidant.

2. The masterbatch for shoe materials according to claim 1, characterized in that, The isocyanate-terminated polyurethane prepolymer is obtained by reacting the following raw materials in parts by mass: 60 parts of polyether polyol, 30 - 50 parts of polyester polyol, 20 - 60 parts of polyisocyanate.

3. The masterbatch for shoe materials according to claim 2, characterized in that, The polyisocyanate includes diisocyanate, and the diisocyanate includes aromatic diisocyanate.

4. The shoe material masterbatch according to claim 3, characterized in that, The polyisocyanate further includes triisocyanate, and the mass percentage content of the triisocyanate in the polyisocyanate is 5% - 15%.

5. The masterbatch for shoe materials according to claim 4, characterized in that, The preparation method of the isocyanate-terminated polyurethane prepolymer includes: first reacting polyether polyol, polyester polyol with diisocyanate, and then adding triisocyanate to react to obtain the isocyanate-terminated polyurethane prepolymer.

6. The masterbatch for shoe materials according to any one of claims 1 to 5, characterized in that, The filler has a through-hole structure, the average particle size of the filler is 0.1 - 3 μm, and the average pore size is 2 - 15 nm.

7. The masterbatch for shoe materials according to any one of claims 1 to 5, characterized in that The raw materials of the shoe material masterbatch satisfy at least one of the following conditions: 1) The water content of the coffee grounds is less than 1 wt%, and the particle size is not greater than 100 mesh; 2) The thermoplastic material includes at least one of polyethylene, ethylene-vinyl acetate copolymer, and natural rubber; 3) The compatibilizer includes at least one of EVA-g-MAH, PE-g-MA, and POE-g-GMA; 4) The antioxidant includes at least one of antioxidant 1010, antioxidant 1076, and antioxidant 264.

8. The masterbatch for shoe materials according to claim 7, wherein The thermoplastic material is polyethylene with a melt index of 2 - 3 g / 10 min; the melt strength of the shoe material masterbatch is not less than 220 mN.

9. A method for preparing a coffee grounds-based masterbatch for shoe materials, characterized in that, Comprising: Providing the raw materials of the shoe material masterbatch according to any one of claims 1 - 8; Mixing the raw materials and then performing melt coextrusion and cooling pelletization to obtain the shoe material masterbatch.

10. A foamed shoe material, characterized in that, Comprising the shoe material masterbatch according to any one of claims 1 - 8 or the shoe material masterbatch prepared by the method according to claim 9.

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