Sole with flexibility and resilience, polyurethane composition and preparation method

Abstract

The invention relates to the technical field of novel polyurethane materials, in particular to a sole with flexibility and rebound resilience, a polyurethane composition and a preparation method. By introducing the low-migration plasticizer, the bio-based softener, the antioxidant, the UV absorbent and the nanofiller, the invention provides the environment-friendly polyurethane sole material with excellent flexibility, rebound resilience and weather resistance, so as to meet the requirements of the market on high-performance and environment-friendly sole materials.

Description

Technical Field

[0001] The invention relates to the technical field of new polyurethane materials, and in particular to a shoe sole with flexibility and resilience, a polyurethane composition and a preparation method. Background Art

[0002] Polyurethane (PU) materials are widely used in the manufacture of sole materials due to their excellent physical properties, such as good flexibility, wear resistance, oil resistance and excellent elasticity. However, traditional polyurethane sole materials are prone to aging, hardening, discoloration and other phenomena during long-term use, especially when exposed to ultraviolet rays, high temperatures or other harsh environments, resulting in a decrease in material performance. In order to solve these problems, researchers have continuously improved the formula based on polyurethane, adding additives such as plasticizers, antioxidants, UV absorbers, etc. to improve its service life and weather resistance.

[0003] Among common polyurethane sole materials, phthalate plasticizers are often used as flexibility modifiers. However, these plasticizers have the problems of high mobility, volatility, and potential harm to the environment and health, and their use has been gradually restricted in recent years. Therefore, seeking low-mobility, low-volatility and environmentally friendly plasticizers has become a research and development focus. At the same time, bio-based materials such as castor oil are gradually introduced into polyurethane formulas as softeners due to their renewability, environmental friendliness and good flexibility, further improving the comfort of the soles.

[0004] In addition, in order to enhance the anti-aging and anti-ultraviolet capabilities of the sole material, antioxidants and UV absorbers are usually added to the formula. Antioxidants can effectively inhibit oxidative degradation reactions caused by external environments such as heat and light, and delay the aging process of the material; while UV absorbers prevent the material from photodegradation by absorbing ultraviolet rays, thereby avoiding the brittleness and yellowing of polyurethane soles after long-term sun exposure.

[0005] Although existing technologies have achieved remarkable results in improving the performance of polyurethane sole materials, how to reduce the use of harmful plasticizers, improve environmental protection, and extend the service life of materials while maintaining the excellent flexibility and elasticity of the sole materials is still an urgent problem to be solved in the industry. Therefore, it is of great significance to develop an environmentally friendly polyurethane sole formula that combines low migration plasticizers and bio-based softeners and has anti-aging and UV resistance. Summary of the invention

[0006] In order to solve the above technical problems, the present invention provides a polyurethane composition for soles with flexibility and resilience. By introducing a low-migration plasticizer, a bio-based softener, an antioxidant, a UV absorber and a nanofiller, an environmentally friendly polyurethane sole material with excellent flexibility, resilience and weather resistance is provided to meet the market demand for high-performance, environmentally friendly sole materials.

[0007] In order to achieve the above-mentioned purpose, the present invention adopts the following technical solutions: A polyurethane composition for shoe soles having flexibility and resilience, wherein the raw materials for preparing the composition include the following components in parts by weight: Polyether polyol: 50-70 parts; Isocyanate: 30-50 parts; Acetyl tributyl citrate: 10-20 parts; Castor oil derivative softener: 5-15 parts; Antioxidants: 0.5-2 parts; UV absorber: 0.1-1 part; Nano-silicon dioxide filler: 1-5 parts; Foaming agent: 1-3 parts; Cross-linking agent: 0.5-2 parts.

[0008] Preferably, the raw materials for preparing the composition include the following components by weight: Polyether polyol: 55-65 parts; Isocyanate: 35-45 parts; Acetyl tributyl citrate: 12-18 parts; Castor oil derivative softener: 8-12 parts; Antioxidant: 0.8-1.5 parts; UV absorber: 0.2-0.5 parts; Nano-silicon dioxide filler: 2-4 parts; Foaming agent: 1.5-0.5 parts; Cross-linking agent: 0.8-1.5 parts.

[0009] Preferably, the polyether polyol is a polyether polyol with a low glass transition temperature, and is selected from propylene glycol polyether diol or propylene glycol polyether triol.

[0010] Preferably, the isocyanate is 4,4'-diphenylmethane diisocyanate (MDI) or toluene diisocyanate (TDI).

[0011] Preferably, the castor oil derivative softener is one or more of castor oil polyether polyol, PEG-40 castor oil, methyl ricinoleate and epoxidized castor oil.

[0012] Preferably, the antioxidant is selected from one or more of BHT (2,6-di-tert-butyl-4-methylphenol), Irganox 1010, Irganox 168, Irganox 1076, Irganox 3114, phosphite antioxidants (such as TNPP), and bisphenol A (BPA).

[0013] Preferably, the UV absorber is a benzophenone UV absorber, specifically selected from one or more of 2-hydroxy-4-methoxybenzophenone (BP-3, Oxybenzone), 2-hydroxy-4-octyloxybenzophenone (BP-12, Octabenzone), 2,2'-dihydroxy-4-methoxybenzophenone (BP-1), 2,2'-dihydroxy-4,4'-dimethoxybenzophenone (BP-6), 2-hydroxy-4-methylbenzophenone (BP-4), 4-octyloxy-2-hydroxybenzophenone (BP-8), benzophenone-10 (BP-10), and 2-hydroxy-4-phenylbenzophenone (BP-11).

[0014] Preferably, the foaming agent is an environmentally friendly physical foaming agent, selected from carbon dioxide or water; the cross-linking agent is trimethylolpropane (TMP).

[0015] Furthermore, the invention also discloses the application of the composition in preparing shoe soles.

[0016] Furthermore, the present invention also discloses a sole with flexibility and resilience, and the sole is prepared from the composition.

[0017] The method for preparing the sole according to claim 9 is characterized in that the method comprises the following steps: 1) Dehydration of polyether polyol: Put the polyether polyol into the reactor and dehydrate it at 110°C for 30-60 minutes to remove the water in the polyol and avoid side reactions with isocyanate in subsequent reactions; the vacuum degree should be controlled at 10-20 mmHg; 2) Mixing isocyanate and polyol: Under stirring conditions, gradually add isocyanate to the dehydrated polyether polyol, maintain the reaction temperature at 60-80°C, and the reaction time is 1-2 hours to generate a reactive polyurethane prepolymer; 3) Temperature control: The temperature of the entire reaction process should be strictly controlled at 60-80°C to avoid excessively high temperatures that may lead to isocyanate decomposition or insufficient cross-linking of polyols; the stirring speed should be maintained at 200-300 rpm; 4) Add low migration plasticizer: During the prepolymer formation process, slowly add acetyl tributyl citrate (ATBC) into the reactor and keep stirring evenly to ensure that it is fully mixed with the prepolymer; 5) Adding the bio-based softener: Add the castor oil-derived bio-based softener into the reactor and continue stirring to evenly mix it with the other ingredients; 6) Add antioxidant and UV absorber: slowly add the weighed antioxidant and UV absorber into the prepolymer and continue stirring to evenly disperse them; 7) Dispersion of nanofillers: At room temperature, disperse the nanosilica filler evenly in the prepolymer using a high-speed stirring disperser at a stirring speed of 2500-4000 rpm for 10-15 minutes to ensure that the filler is evenly distributed in the matrix; 8) Adding foaming agent: Slowly inject carbon dioxide or water into the system as a foaming agent, and control the injection amount to 1-2 parts; the temperature during the foaming process should be controlled at 50-70℃; 7) Addition of cross-linking agent: After the foaming agent is mixed, add the cross-linking agent trimethylolpropane and continue stirring to ensure that the cross-linking agent reacts fully with other ingredients to form a polyurethane network structure with good cross-linking density; 8) Mold preparation: Before pouring, preheat the mold to 50-60℃ and apply an appropriate amount of release agent to ensure that the product is easy to demold; 9) Casting process: Pour the uniformly mixed polyurethane composition slurry into the mold, control the temperature at 50-60℃, and start foaming after the mold is filled. During the foaming process, pay attention to controlling the pressure in the mold to make the foaming uniform and avoid bubbles or uneven structure; 10) Curing: Preliminary curing is carried out at 60°C, and the curing time is about 30-60 minutes; 11) Place the preliminarily cured sole in an oven and perform post-curing at 80-100°C for 2-4 hours.

[0018] The present invention adopts the above technical solution to provide an environmentally friendly polyurethane sole composition with excellent flexibility and resilience. The composition not only has a breakthrough in performance, but also significantly improves its environmental protection and durability by selecting low-migration plasticizers, bio-based softeners, antioxidants, UV absorbers, nanofillers and other additives. The specific technical effects are reflected in the following aspects: 1. Improve the flexibility and resilience of the sole: By introducing low-migration plasticizers (such as acetyl tributyl citrate) and bio-based softeners (such as castor oil derivatives) into the formula, the glass transition temperature of the material is effectively reduced, so that the sole material can maintain good flexibility and resilience in both low and high temperature environments, thereby improving the comfort and cushioning performance of the sole.

[0019] 2. Enhanced anti-aging performance: The present invention uses a variety of high-efficiency antioxidants (such as Irganox 1010 and BHT), which can effectively prevent the polyurethane material from oxidative degradation when exposed to air, light and high temperature for a long time. The introduction of antioxidants significantly extends the service life of the sole material and avoids problems such as embrittlement and cracking due to aging.

[0020] 3. Improve anti-ultraviolet performance: By adding benzophenone UV absorbers (such as BP-3, BP-12, etc.), the sole material has strong anti-ultraviolet ability, can effectively absorb ultraviolet rays in the UV-A and UV-B bands, prevent the material from photodegradation, and avoid discoloration, hardening and performance degradation caused by long-term exposure of the sole to sunlight.

[0021] 4. Improve the wear resistance and mechanical properties of materials: The addition of nano-silicon dioxide as a filler not only improves the mechanical strength of the material, but also enhances the wear resistance and tear resistance of the sole. The nano-filler is evenly distributed in the matrix to form a dense microstructure, which significantly improves the durability of the sole material during actual use.

[0022] 5. Environmental protection and low toxicity: The low migration plasticizer and bio-based softener used in the present invention have low volatility and migration, avoiding the potential harm of traditional phthalate plasticizers to human health and the environment. By using castor oil-derived softeners, the dependence on petrochemical resources is further reduced, and the sustainability and environmental protection of the material are improved.

[0023] 6. Controllable process, easy for industrial production: The preparation process of the invention is simple, easy to operate, and suitable for large-scale industrial production. By controlling the reasonable reaction temperature, stirring speed and foaming conditions, the uniformity and performance stability of the material can be ensured, which is suitable for the manufacturing process of various soles.

[0024] In summary, the polyurethane sole composition of the present invention not only has excellent mechanical properties and weather resistance, but also takes into account environmental protection and comfort, meets the demand of the modern footwear market for high-performance and environmentally friendly materials, and significantly extends the service life of the sole. DETAILED DESCRIPTION

[0026] The following is a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the embodiments of the present invention. Obviously, the described embodiments 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 creative work are within the scope of protection of the present invention.

[0027] Example 1 Formula composition (by weight): Polyether polyol (propylene glycol polyether glycol): 60 parts Isocyanate (MDI): 40 parts Acetyl tributyl citrate (ATBC): 15 parts Methyl ricinoleate: 10 parts Antioxidant (Irganox 1010): 1 serving UV absorber (BP-3): 0.5 parts Nano silica filler: 2 parts Foaming agent (carbon dioxide): 2 parts Crosslinking agent (trimethylolpropane, TMP): 1 part.

[0028] Preparation process: 1) Dehydrate the polyether polyol at 110°C for 30 minutes with a vacuum degree of 15 mmHg.

[0029] 2) Slowly add MDI isocyanate to the dehydrated polyether polyol and stir at 60-80°C for 1 hour to generate a prepolymer.

[0030] 3) Add acetyl tributyl citrate and methyl ricinoleate and stir well.

[0031] 4) Add antioxidant Irganox 1010 and UV absorber BP-3 respectively and stir evenly.

[0032] 5) Disperse the nano-silica by a high-speed disperser (3000 rpm) for 10 minutes.

[0033] 6) Inject carbon dioxide foaming agent and add cross-linking agent TMP, and continue stirring.

[0034] 7) The mixture was poured into a mold with the mold temperature controlled at 55°C and initially cured at 60°C for 40 minutes.

[0035] 8) Post-curing treatment at 80° C. for 3 hours, and demoulding after cooling to obtain a shoe sole.

[0036] Example 2 Formula composition (by weight): Polyether polyol (propylene glycol polyether triol): 55 parts Isocyanate (TDI): 45 parts Acetyl tributyl citrate (ATBC): 12 parts Castor oil polyether polyol: 8 parts Antioxidant (BHT): 1.5 parts UV absorber (BP-12): 0.3 parts Nano silica filler: 3 parts Foaming agent (water): 1.5 parts Crosslinking agent (trimethylolpropane, TMP): 1.2 parts.

[0037] Preparation process: 1) Dehydrate the polyether polyol at 110°C for 40 minutes with a vacuum degree of 18 mmHg.

[0038] 2) Slowly add TDI isocyanate to the dehydrated polyether at 70°C and stir for 1 hour to generate a prepolymer.

[0039] 3) Add acetyl tributyl citrate and castor oil polyether polyol and stir well.

[0040] 4) Add antioxidant BHT and UV absorber BP-12 respectively, and stir until completely mixed.

[0041] 5) Nano-silica was dispersed by high-speed stirrer (3500 rpm) at room temperature for 15 min.

[0042] 6) Inject water as a foaming agent, then add the cross-linking agent TMP and continue to stir evenly.

[0043] 7) Pour the mixture into a mold preheated to 60°C and cure for 50 minutes.

[0044] 8) Post-curing treatment at 90° C. for 4 hours, and demoulding after cooling to obtain a shoe sole.

[0045] Example 3 Formula composition (by weight): Polyether polyol (propylene glycol polyether glycol): 65 parts Isocyanate (MDI): 35 parts Acetyl tributyl citrate (ATBC): 18 parts Epoxidized castor oil: 12 parts Antioxidant (Irganox 3114): 1.2 parts UV absorber (BP-8): 0.4 parts Nano-silica filler: 1.5 parts Foaming agent (water): 2 parts Crosslinking agent (trimethylolpropane, TMP): 0.8 parts; Preparation process: 1) Dehydrate the polyether polyol at 120°C for 30 minutes with a vacuum degree of 12 mmHg.

[0046] 2) Add MDI isocyanate to the dehydrated polyether at 75°C and stir for 1 hour to form a prepolymer.

[0047] 3) Add acetyl tributyl citrate and epoxidized castor oil and stir well.

[0048] 4) Add antioxidant Irganox 3114 and UV absorber BP-8 and stir until fully mixed.

[0049] 5) The nano-silica was dispersed by high-speed stirring at 3500 rpm for 12 minutes.

[0050] 6) Add the foaming agent water, then add the cross-linking agent TMP, and continue to stir evenly.

[0051] 7) Pour the mixture into a mold, maintain the mold temperature at 50°C, and initially cure for 30 minutes.

[0052] 8) Post-curing treatment was performed at 100° C. for 3 hours, and the sole was obtained after demoulding.

[0053] Comparative Example 1 Formula composition (by weight): Polyether polyol (propylene glycol polyether glycol): 60 parts Isocyanate (MDI): 40 parts Dioctyl phthalate (DOP): 15 parts Antioxidant (Irganox 1010): 1 serving UV absorber (BP-3): 0.5 parts Nano silica filler: 2 parts Foaming agent (carbon dioxide): 2 parts Crosslinking agent (trimethylolpropane, TMP): 1 part.

[0054] Preparation process: 1) Dehydrate the polyether polyol at 110°C for 30 minutes with a vacuum degree of 15 mmHg.

[0055] 2) Slowly add MDI isocyanate to the dehydrated polyether polyol and stir at 60-80°C for 1 hour to generate a prepolymer.

[0056] 3) Add dioctyl phthalate and stir well.

[0057] 4) Add antioxidant Irganox 1010 and UV absorber BP-3 respectively and stir evenly.

[0058] 5) Disperse the nano-silica by a high-speed disperser (3000 rpm) for 10 minutes.

[0059] 6) Inject carbon dioxide foaming agent and add cross-linking agent TMP, and continue stirring.

[0060] 7) The mixture was poured into a mold with the mold temperature controlled at 55°C and initially cured at 60°C for 40 minutes.

[0061] 8) Post-curing treatment at 80° C. for 3 hours, and demoulding after cooling to obtain a shoe sole.

[0062] Comparative Example 2 Formula composition (by weight): Polyether polyol (propylene glycol polyether glycol): 60 parts Isocyanate (MDI): 40 parts Trioctyl citrate (TBC): 15 parts Antioxidant (Irganox 1010): 1 serving UV absorber (BP-3): 0.5 parts Nano silica filler: 2 parts Foaming agent (carbon dioxide): 2 parts Crosslinking agent (trimethylolpropane, TMP): 1 part.

[0063] Preparation process: 1) Dehydrate the polyether polyol at 110°C for 30 minutes with a vacuum degree of 15 mmHg.

[0064] 2) Slowly add MDI isocyanate to the dehydrated polyether polyol and stir at 60-80°C for 1 hour to generate a prepolymer.

[0065] 3) Add dioctyl phthalate and stir well.

[0066] 4) Add antioxidant Irganox 1010 and UV absorber BP-3 respectively and stir evenly.

[0067] 5) Disperse the nano-silica by a high-speed disperser (3000 rpm) for 10 minutes.

[0068] 6) Inject carbon dioxide foaming agent and add cross-linking agent TMP, and continue stirring.

[0069] 7) The mixture was poured into a mold with the mold temperature controlled at 55°C and initially cured at 60°C for 40 minutes.

[0070] 8) Post-curing treatment at 80° C. for 3 hours, and demoulding after cooling to obtain a shoe sole.

[0071] Comparative Example 3 Formula composition (by weight): Polyether polyol (propylene glycol polyether glycol): 60 parts Isocyanate (MDI): 40 parts Dioctyl phthalate (DOP): 15 parts Methyl ricinoleate: 10 parts Antioxidant (Irganox 1010): 1 serving UV absorber (BP-3): 0.5 parts Nano silica filler: 2 parts Foaming agent (carbon dioxide): 2 parts Crosslinking agent (trimethylolpropane, TMP): 1 part.

[0072] Preparation process: 1) Dehydrate the polyether polyol at 110°C for 30 minutes with a vacuum degree of 15 mmHg.

[0073] 2) Slowly add MDI isocyanate to the dehydrated polyether polyol and stir at 60-80°C for 1 hour to generate a prepolymer.

[0074] 3) Add dioctyl phthalate and methyl ricinoleate and stir well.

[0075] 4) Add antioxidant Irganox 1010 and UV absorber BP-3 respectively and stir evenly.

[0076] 5) Disperse the nano-silica by a high-speed disperser (3000 rpm) for 10 minutes.

[0077] 6) Inject carbon dioxide foaming agent and add cross-linking agent TMP, and continue stirring.

[0078] 7) The mixture was poured into a mold with the mold temperature controlled at 55°C and initially cured at 60°C for 40 minutes.

[0079] 8) Post-curing treatment at 80° C. for 3 hours, and demoulding after cooling to obtain a shoe sole.

[0080] Test example 1. Flexibility testing process The flexibility test is used to evaluate the material's ability to resist fracture and deformation under external forces. The tensile test method is usually used to determine the tensile strength (MPa) of polyurethane sole materials. The following are the specific test steps: Equipment and tools: tensile testing machine, standard specimen die (dumbbell-shaped specimen), vernier caliper, constant temperature and humidity environment (temperature 23±2℃, humidity 50±5%).

[0081] Test steps: 1) Prepare the specimen: According to ASTM D412 or ISO 37, use a die cutter to cut a dumbbell-shaped specimen from the sole material. The specimen size should meet the standard requirements.

[0082] 2) Mark the initial length: Use a vernier caliper to mark the nominal length (usually 25-50 mm) on the specimen.

[0083] 3) Clamp the specimen: Clamp both ends of the dumbbell-shaped specimen in the clamps of the tensile testing machine, ensuring that the specimen remains vertical and aligned during the stretching process.

[0084] 4) Tensile test: Stretch the specimen at a constant speed (usually 50 mm / min) and record the maximum stress when the material breaks, which is the flexibility (tensile strength).

[0085] Record results: Repeat the test at least 3 times and take the average value as the final result of the flexibility test.

[0086] 2. Resilience test process The rebound test evaluates the ability of the sole material to recover to its original shape after compression deformation, usually by the falling ball rebound method. This test simulates the cushioning and elastic properties of the sole material during movement.

[0087] Equipment and tools: Rebound testing machine (or falling ball rebound tester), steel ball (mass 100 g), measuring ruler.

[0088] Test steps: 1) Prepare the sample: Cut the sole material into square samples with a size of 100 mm x 100 mm x 10 mm and ensure the surface is flat.

[0089] 2) Initial height setting: Place the steel ball at the specified height of the rebound testing machine (usually 50 cm or 1 m) so that the steel ball falls vertically on the center of the specimen.

[0090] 3) Record the rebound height: After the steel ball hits the sample, it will bounce back. By measuring the maximum rebound height, calculate the rebound rate. The rebound rate calculation formula is: 4) Repeat the test: Repeat the test at least 3 times and take the average value as the final result of the rebound test.

[0091] 3. Wear resistance test process Wear resistance testing evaluates the material's ability to resist wear under friction, and is usually performed using an Akron abrasion tester or a DIN wear tester.

[0092] Equipment and tools: DIN abrasion test machine (wear wheel), standard rubber specimen (for calibration), balance (accurate to 0.001 g).

[0093] Test steps: 1) Prepare the specimen: Cut the sole material into cylindrical specimens with a diameter of 16 mm and a thickness of 6-10 mm.

[0094] 2) Calibrate equipment: Use standard rubber specimens to calibrate the DIN wear tester to ensure that the equipment is in accurate working condition.

[0095] 3) Install the sample: Fix the sole sample on the wear wheel and set the loading weight (usually 10 N).

[0096] 4) Start the test: The abrasion wheel rotates at a constant speed (usually 40 m / min) and the weight loss of the sample after friction is recorded.

[0097] 5) Calculate wear resistance: The calculation formula for wear loss is: 6) Repeat test: Each sample is tested at least 3 times, and the average value is taken as the final result of the wear resistance test.

[0098] 4. UV resistance test process UV resistance testing evaluates the stability of materials under long-term UV exposure. Usually, UV aging test chambers are used to perform UV accelerated aging tests to simulate the aging behavior of materials under long-term sunlight conditions.

[0099] Equipment and tools: UV aging test chamber, material samples (100 mm x 100 mm).

[0100] Test steps: 1) Sample preparation: Cut the sole material into specimens of 100 mm x 100 mm, ensuring that the surface is flat and smooth.

[0101] 2) Set equipment parameters: Set the UV aging test chamber to a UV intensity of 0.75 W / m² and a temperature of 50°C.

[0102] 3) Sample placement: Place the sample in a test chamber and expose it to a UV light source to simulate 1 month of sun exposure.

[0103] 4) Regular inspection: Check the surface condition of the sample every 7 days and record aging phenomena such as color change, hardness change, cracks, etc.

[0104] 5) Record results: After the test period, analyze the appearance changes and physical properties of the material and evaluate its UV resistance.

[0105] Experimental data of embodiments and comparative examples Experiment Name Flexibility (MPa) Resilience(%) Wear resistance (mg loss) UV resistance Example 1 18 65 120 No significant changes Example 2 17 62 130 No significant changes Example 3 19 68 115 No significant changes Comparative Example 1 10 40 154 Slight discoloration Comparative Example 2 12 45 143 Slight discoloration Comparative Example 3 15 55 125 Slight discoloration The above table gives the flexibility, resilience, wear resistance and UV resistance performance data of the embodiment and the comparative example experiments. It can be seen from these experimental data that the soles of the embodiment are significantly better than the comparative example sole materials in flexibility, resilience, wear resistance and UV resistance.

[0106] 5. Plasticizer low migration test Plasticizer low migration experiments usually evaluate the impact of plasticizer volatilization and migration during use to evaluate its impact on material properties. Common low migration plasticizer experimental data include weight loss rate and migration rate.

[0107] Testing process: 1) Sample preparation: The polyurethane sole materials containing different plasticizers were cut into samples with a size of 100 mm x 100 mm x 10 mm.

[0108] 2) Test conditions: The sample is placed in a constant temperature box, the temperature is set to 80°C, and the test is continued for 24 hours.

[0109] 3) Weight loss rate: Weigh the sample before and after the test, and calculate the weight loss rate to reflect the volatility of the plasticizer. The calculation formula is: 4) Migration rate: Place the sample in contact with a standard test plate and test the migration rate of the plasticizer after a certain period of time. The unit of calculation of the migration rate is mg / cm².

[0110] Plasticizer low migration test data Experiment Name Plasticizer Type Weight loss rate (%) Migration rate (mg / cm²) Example 1 Acetyl tributyl citrate (ATBC) 0.23% 0.05 Example 2 Acetyl tributyl citrate (ATBC) 0.32% 0.07 Example 3 Acetyl tributyl citrate (ATBC) 0.25% 0.04 Comparative Example 1 Dioctyl phthalate (DOP) 1.5% 0.80 Comparative Example 2 Trioctyl Citrate (TBC) 1.0% 0.60 Comparative Example 3 Dioctyl phthalate (DOP) 1.2% 0.75 The material of the embodiment (using acetyl tributyl citrate (ATBC) as a plasticizer) exhibits a lower weight loss rate and migration rate, indicating that its low migration is significantly better than that of traditional phthalate plasticizers (DOP) and trioctyl citrate (TBC). These results demonstrate the effectiveness of ATBC in the present invention, which not only improves the flexibility of the material, but also ensures its safety and stability for long-term use.

[0111] The above is a description of the embodiments of the present invention. Through the above description of the disclosed embodiments, professionals and technicians in the field can implement or use the present invention. Various modifications to these embodiments will be apparent to professionals and technicians in the field. The general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown in this article, but will conform to the widest range consistent with the principles and novelties disclosed herein.

Claims

1. A polyurethane composition for shoe soles having flexibility and resilience, characterized in that: The raw materials for preparing the composition include the following components by weight: Polyether polyol: 50-70 parts; Isocyanate: 30-50 parts; Acetyl tributyl citrate: 10-20 parts; Castor oil derivative softener: 5-15 parts; Antioxidants: 0.5-2 parts; UV absorber: 0.1-1 part; Nano-silicon dioxide filler: 1-5 parts; Foaming agent: 1-3 parts; Cross-linking agent: 0.5-2 parts.

2. The polyurethane composition according to claim 1, characterized in that The raw materials for preparing the composition include the following components by weight: Polyether polyol: 55-65 parts; Isocyanate: 35-45 parts; Acetyl tributyl citrate: 12-18 parts; Castor oil derivative softener: 8-12 parts; Antioxidant: 0.8-1.5 parts; UV absorber: 0.2-0.5 parts; Nano-silicon dioxide filler: 2-4 parts; Foaming agent: 1.5-0.5 parts; Cross-linking agent: 0.8-1.5 parts.

3. The polyurethane composition according to claim 1, characterized in that The polyether polyol is a polyether polyol with a low glass transition temperature, and is selected from propylene glycol polyether diol or propylene glycol polyether triol.

4. The polyurethane composition according to claim 1, characterized in that The isocyanate is 4,4'-diphenylmethane diisocyanate (MDI) or toluene diisocyanate (TDI).

5. The polyurethane composition according to claim 1, characterized in that The castor oil derivative softener is one or more of castor oil polyether polyol, PEG-40 castor oil, methyl ricinoleate and epoxidized castor oil.

6. The polyurethane composition according to claim 1, characterized in that The antioxidant is selected from one or more of BHT (2,6-di-tert-butyl-4-methylphenol), Irganox 1010, Irganox 168, Irganox 1076, Irganox 3114, phosphite antioxidants (such as TNPP), and bisphenol A (BPA).

7. The polyurethane composition according to claim 1, characterized in that The UV absorber is a benzophenone UV absorber, specifically selected from one or more of 2-hydroxy-4-methoxybenzophenone (BP-3, Oxybenzone), 2-hydroxy-4-octyloxybenzophenone (BP-12, Octabenzone), 2,2'-dihydroxy-4-methoxybenzophenone (BP-1), 2,2'-dihydroxy-4,4'-dimethoxybenzophenone (BP-6), 2-hydroxy-4-methylbenzophenone (BP-4), 4-octyloxy-2-hydroxybenzophenone (BP-8), benzophenone-10 (BP-10), and 2-hydroxy-4-phenylbenzophenone (BP-11).

8. The polyurethane composition according to claim 1, characterized in that The foaming agent is an environmentally friendly physical foaming agent, which can be carbon dioxide or water; the cross-linking agent is trimethylolpropane (TMP).

9. A sole having flexibility and resilience, characterized in that: The shoe sole is prepared from the composition described in any one of claims 1 to 8.

10. The method for preparing the sole according to claim 9, characterized in that: The method comprises the following steps: 1) Dehydration of polyether polyol: Put the polyether polyol into the reactor and dehydrate it at 110°C for 30-60 minutes to remove the water in the polyol. The vacuum degree should be controlled at 10-20 mmHg; 2) Mixing isocyanate and polyol: Under stirring conditions, gradually add isocyanate to the dehydrated polyether polyol, maintain the reaction temperature at 60-80°C, and the reaction time is 1-2 hours to generate a reactive polyurethane prepolymer; 3) Temperature control: The temperature of the entire reaction process should be strictly controlled at 60-80°C; the stirring speed should be maintained at 200-300rpm; 4) Add low migration plasticizer: During the prepolymer formation process, slowly add acetyl tributyl citrate (ATBC) into the reactor and keep stirring evenly to fully mix with the prepolymer; 5) Adding the bio-based softener: Add the castor oil-derived bio-based softener into the reactor and continue stirring to evenly mix it with the other ingredients; 6) Add antioxidant and UV absorber: slowly add the weighed antioxidant and UV absorber into the prepolymer and continue stirring to evenly disperse them; 7) Dispersion of nanofillers: At room temperature, disperse the nanosilica filler evenly in the prepolymer through a high-speed stirring disperser at a stirring speed of 2500-4000 rpm for 10-15 minutes to make the filler evenly distributed in the matrix; 8) Adding foaming agent: Slowly inject carbon dioxide or water into the system as a foaming agent, and control the injection amount to 1-2 parts; the temperature during the foaming process should be controlled at 50-70℃; 7) Addition of cross-linking agent: After the foaming agent is mixed, add trimethylolpropane, a cross-linking agent, and continue stirring to allow the cross-linking agent to fully react with other ingredients; 8) Mold preparation: Before pouring, preheat the mold to 50-60℃ and apply an appropriate amount of release agent; 9) Casting process: pour the uniformly mixed polyurethane composition slurry into the mold, control the temperature at 50-60°C, and start foaming after the mold is filled; 10) Curing: Preliminary curing is carried out at 60°C, and the curing time is about 30-60 minutes; 11) Place the preliminarily cured sole in an oven and perform post-curing at 80-100°C for 2-4 hours.

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