Environment-friendly aliphatic TPU (thermoplastic polyurethane) elastic plastic

Abstract

The invention belongs to the technical field of high polymer materials, and particularly relates to environment-friendly aliphatic TPU (thermoplastic polyurethane) elastic plastic. The bio-based polyurethane elastomer is prepared from the following raw materials in parts by weight: 60 to 65 parts of bio-based polyester polyol, 25 to 30 parts of aliphatic diisocyanate, 5 to 8 parts of silane coupling agent grafted nano cellulose whisker, 1.5 to 2.5 parts of chain extender, 0.5 to 1 part of bio-based organic tin catalyst, 0.3 to 0.7 part of antioxidant and the like. Compared with the prior art, the invention has the following beneficial effects: environment-friendly raw materials such as bio-based polyester polyol, bio-based organic tin catalyst and the like are adopted, and the degradable nano-cellulose whisker is used as a reinforcing agent, so that the use of petrochemical raw materials is reduced from the source, the environmental pollution is reduced, and the material is easy to degrade after being used, and is environment-friendly. The TPU elastic plastic prepared by the preparation method disclosed by the invention meets the modern environmental protection concept, and the TPU elastic plastic has excellent elasticity, wear resistance and weather resistance due to the elaborately designed raw material ratio, so that the TPU elastic plastic has wide application potential in the field of shoe materials.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials, and in particular relates to an environmentally friendly aliphatic TPU elastic plastic. Background Art

[0002] In the current plastics industry, thermoplastic polyurethane (TPU) elastic plastics are widely used in many fields such as footwear, automotive parts, wires and cables, and medical equipment due to their unique elasticity, wear resistance, and weather resistance. However, despite the many advantages of TPU elastic plastics, traditional TPU elastic plastics still have obvious shortcomings in terms of component analysis and composition.

[0003] First, from the perspective of raw material sources, traditional TPU elastic plastics mainly rely on petrochemical raw materials, such as oil and natural gas. These raw materials are not only limited in resources, but also produce a large amount of greenhouse gases, wastewater, waste residue and other pollutants during the production process, causing serious damage to the environment. In addition, with the intensification of the global energy crisis, the price of petrochemical raw materials continues to rise, which increases the production cost of traditional TPU elastic plastics.

[0004] Secondly, from the perspective of component analysis, traditional TPU elastic plastics often contain a large amount of auxiliary materials such as plasticizers, stabilizers, and flame retardants. Although these auxiliary materials improve the performance of TPU elastic plastics to a certain extent, they are easy to precipitate during long-term use, resulting in a decrease in material performance and even potential threats to human health. For example, some plasticizers may be carcinogenic, while flame retardants may pollute the environment.

[0005] Furthermore, traditional TPU elastic plastics also have great difficulties in recycling and processing. Due to their non-degradable properties, discarded TPU elastic plastics are often landfilled or incinerated, which not only wastes resources but also aggravates environmental pollution problems. Landfilling will occupy a large amount of land resources and may pollute the soil and groundwater; while incineration will produce a large amount of toxic and harmful gases and smoke, which will have a serious impact on the atmospheric environment. Summary of the invention

[0006] 1. Technical issues to be resolved

[0007] The present invention aims at solving the problems existing in the raw material source, component composition and recycling treatment of traditional thermoplastic polyurethane (TPU) elastic plastics. Therefore, the present invention provides an environmentally friendly aliphatic TPU elastic plastic mainly based on bio-based raw materials and having excellent elasticity.

[0008] (II) Technical solution

[0009] The present invention is achieved through the following technical scheme: The present invention proposes an environmentally friendly aliphatic TPU elastic plastic, wherein the elastic plastic is prepared from raw materials including, by weight: 60-65 parts of bio-based polyester polyol, 25-30 parts of aliphatic diisocyanate, 5-8 parts of nanocellulose whiskers grafted with a silane coupling agent, 1.5-2.5 parts of a chain extender, 0.5-1 parts of a bio-based organic tin catalyst, and 0.3-0.7 parts of an antioxidant;

[0010] Among them, the molecular weight range of bio-based polyester polyols is 2000-4000g / mol, and the hydroxyl value is 45-55mgKOH / g;

[0011] The grafting rate of silane coupling agent is 8%-12%;

[0012] The activity index of bio-based organotin catalysts is 0.9-1.1.

[0013] Preferably, the bio-based polyester polyol is prepared by polycondensation of bio-based diol and bio-based dibasic acid.

[0014] Preferably, the nanocellulose whiskers have a length of 100-150 nm and a diameter of 10-15 nm.

[0015] Preferably, the molar ratio of NCO / OH in the aliphatic diisocyanate to the bio-based polyester polyol is between 1.05:1 and 1.15:1.

[0016] Preferably, the nanocellulose whiskers grafted with silane coupling agent are prepared by dispersing nanocellulose whiskers in an ethanol solution, and then adding a silane coupling agent to react, the reaction temperature is 90-110° C., and the reaction time is 3-5 hours.

[0017] Preferably, the aliphatic diisocyanate is hexamethylene diisocyanate, or an aqueous dispersion of hexamethylene diisocyanate, or a trimer of hexamethylene diisocyanate, or an allophanate prepolymer of hexamethylene diisocyanate.

[0018] Preferably, the chain extender is one or more of 1,4-butanediol and 1,6-hexanediol.

[0019] Preferably, the antioxidant is one or more of tea polyphenols and vitamin E.

[0020] Preferably, the bio-based organotin catalyst is one or more of dimethyltin dilaurate and dibutyltin dilaurate.

[0021] For the application of any of the above-mentioned environmentally friendly aliphatic TPU elastic plastics in shoe materials, the elastic plastic needs to be processed and formed, and the steps are to process the TPU particles into soles, uppers or other shoe parts through molding processes such as injection molding and extrusion. During injection molding, the barrel temperature is controlled at 170-220°C, and the injection pressure is generally 141-9Mpa. During extrusion molding, the barrel temperature is between 171-220°C, and the screw speed is preferably 20-80rpm.

[0022] The present invention also provides a production process of any one of the above-mentioned environmentally friendly aliphatic TPU elastic plastics, which mainly comprises the following steps:

[0023] 1st) Raw materials preparation:

[0024] Preparation of bio-based polyester polyols:

[0025] Raw material selection: select bio-based diols (such as diols derived from renewable resources, such as corn sugar alcohol, soybean oil alcohol, etc.) and bio-based dibasic acids (such as dibasic acids derived from biological fermentation, such as succinic acid, glutaric acid, etc.) that meet the requirements;

[0026] Polycondensation reaction: under nitrogen protection, add bio-based diol and bio-based dibasic acid into the reactor in a certain proportion, heat to an appropriate temperature (usually 180-220°C), add an appropriate amount of catalyst (such as titanate catalyst), and carry out polycondensation reaction until the target molecular weight (2000-4000g / mol) and hydroxyl value (45-55mgKOH / g) are reached;

[0027] Post-treatment: After the reaction is completed, the temperature is lowered, the material is discharged, and post-treatments such as filtration and degassing are performed to obtain bio-based polyester polyols;

[0028] Preparation of silane coupling agent grafted nanocellulose whiskers:

[0029] Dispersion: Disperse the nanocellulose whiskers evenly in the ethanol solution;

[0030] Grafting reaction: add appropriate amount of silane coupling agent, react at 90-110℃ for 3-5 hours, and control the grafting rate at 8%-12%;

[0031] Washing and drying: After the reaction is completed, the product is washed with ethanol to remove the unreacted silane coupling agent, and then dried to obtain the nanocellulose whiskers grafted with the silane coupling agent;

[0032] 2nd)TPU synthesis

[0033] Pre-polymerization:

[0034] Mixing: adding the measured bio-based polyester polyol and aliphatic diisocyanate (such as hexamethylene diisocyanate or its variant) into the reactor, controlling the NCO / OH molar ratio between 1.05:1 and 1.15:1;

[0035] Reaction: Under nitrogen protection, heat to an appropriate temperature (usually 70-90°C) to carry out prepolymerization reaction until the predetermined NCO content is reached;

[0036] Chain extension and cross-linking:

[0037] Adding chain extender: When the prepolymerization reaction reaches the predetermined stage, add a measured chain extender (such as 1,4-butanediol, 1,6-hexanediol) and continue the reaction;

[0038] Adding catalysts and additives: Adding bio-based organic tin catalysts (such as dimethyltin dilaurate, dibutyltin dilaurate) and antioxidants (such as tea polyphenols, vitamin E) at the same time to promote the reaction and improve product performance;

[0039] End point control: Control the reaction end point by monitoring the viscosity or NCO content of the reaction system;

[0040] Post-processing:

[0041] Degassing: After the reaction is completed, vacuum degassing is performed to remove the gas and small molecular by-products produced in the reaction;

[0042] Cooling and pelletizing: After the reaction product is cooled to an appropriate temperature, it is cut into pellets by a pelletizer to obtain an environmentally friendly aliphatic TPU elastic plastic product.

[0043] 3rd) Quality inspection and packaging

[0044] Quality testing: Conduct performance tests on finished products, including tensile strength, elongation at break, hardness, heat resistance and other indicators to ensure that the products meet the design requirements;

[0045] Packaging and storage: Pack qualified products into warehouses, protect them from moisture and sunlight, and store them in a cool and dry place.

[0046] (III) Beneficial effects

[0047] Compared with the prior art, the present invention has the following beneficial effects: the present invention adopts environmentally friendly raw materials such as bio-based polyester polyols, bio-based organic tin catalysts, and degradable nanocellulose whiskers as reinforcing agents, thereby reducing the use of petrochemical raw materials from the source and reducing environmental pollution. At the same time, the material is easy to degrade after use, which conforms to modern environmental protection concepts and helps promote the green transformation of the polymer material industry. In addition, through the carefully designed raw material ratio, the TPU elastic plastic obtained by the present invention has excellent elasticity, wear resistance and weather resistance. These properties make the material have wide application potential in multiple fields, such as shoe materials, automotive interiors, sports equipment, etc. DETAILED DESCRIPTION

[0048] In this technical solution:

[0049] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0050] The present invention is achieved through the following technical scheme: The present invention proposes an environmentally friendly aliphatic TPU elastic plastic, wherein the elastic plastic is prepared from raw materials including, by weight: 60-65 parts of bio-based polyester polyol, 25-30 parts of aliphatic diisocyanate, 5-8 parts of nanocellulose whiskers grafted with a silane coupling agent, 1.5-2.5 parts of a chain extender, 0.5-1 parts of a bio-based organic tin catalyst, and 0.3-0.7 parts of an antioxidant;

[0051] The molecular weight of bio-based polyester polyols ranges from 2000 to 4000 g / mol, and the hydroxyl value is 45 to 55 mgKOH / g to ensure the stability and reactivity of the material.

[0052] The grafting rate of silane coupling agent is 8%-12% to improve the compatibility of nanocellulose whiskers with TPU matrix;

[0053] The activity index of the bio-based organotin catalyst is 0.9-1.1, providing a highly efficient catalytic effect;

[0054] Specifically, the bio-based polyester polyol is prepared by polycondensation of bio-based diol and bio-based dibasic acid, which ensures the environmental friendliness and renewability of the raw materials. The addition of nanocellulose whiskers enhances the strength and toughness of the material. At the same time, the grafting of silane coupling agent improves its compatibility with the matrix. Aliphatic diisocyanate is used as a cross-linking agent to react with bio-based polyester polyol to form the skeleton structure of TPU. Chain extender is used to adjust the molecular weight and improve the processing performance of the material. Bio-based organic tin catalyst is used to accelerate the reaction process and improve production efficiency. The addition of antioxidant effectively prolongs the service life of the material.

[0055] The bio-based polyester polyol is prepared by polycondensation of bio-based diol and bio-based dibasic acid, which gives the material higher biodegradability and environmental friendliness;

[0056] The length of the nanocellulose whiskers is 100-150 nm and the diameter is 10-15 nm. Such a size distribution helps to enhance the mechanical properties and processing properties of TPU.

[0057] The molar ratio of NCO / OH in the aliphatic diisocyanate to the bio-based polyester polyol is between 1.05:1 and 1.15:1, so as to ensure that the crosslinking density and mechanical properties of the TPU are optimally balanced;

[0058] The nanocellulose whiskers grafted with silane coupling agent are prepared by dispersing nanocellulose whiskers in an ethanol solution, and then adding a silane coupling agent to react, the reaction temperature is 90-110° C., and the reaction time is 3-5 hours, so as to obtain good grafting effect and dispersibility;

[0059] Wherein, the aliphatic diisocyanate is hexamethylene diisocyanate, or an aqueous dispersion of hexamethylene diisocyanate, or a trimer of hexamethylene diisocyanate, or an allophanate prepolymer of hexamethylene diisocyanate, so as to further reduce environmental pollution in the production process;

[0060] Wherein, the chain extender is one or more of 1,4-butanediol and 1,6-hexanediol to adjust the hardness and tensile strength of TPU;

[0061] Wherein, the antioxidant is one or more of tea polyphenols and vitamin E. These natural antioxidants can not only effectively prevent material aging, but also improve the safety and environmental protection of the product;

[0062] Wherein, the bio-based organotin catalyst is one or more of dimethyltin dilaurate and dibutyltin dilaurate, which not only have efficient catalytic performance, but also can reduce potential harm to human body and environment;

[0063] The application of any of the above-mentioned environmentally friendly aliphatic TPU elastic plastics in shoe materials requires the elastic plastic to be processed and formed, and the steps are to process the TPU particles into soles, uppers or other shoe parts through molding processes such as injection molding and extrusion. During injection molding, the barrel temperature is controlled at 170-220°C, and the injection pressure is generally 141-9Mpa. During extrusion molding, the barrel temperature is between 171-220°C, and the screw speed is preferably 20-80rpm;

[0064] The present invention also provides a production process of any one of the above-mentioned environmentally friendly aliphatic TPU elastic plastics, which mainly comprises the following steps:

[0065] 1st) Raw materials preparation:

[0066] Preparation of bio-based polyester polyols:

[0067] Raw material selection: select bio-based diols (such as diols derived from renewable resources, such as corn sugar alcohol, soybean oil alcohol, etc.) and bio-based dibasic acids (such as dibasic acids derived from biological fermentation, such as succinic acid, glutaric acid, etc.) that meet the requirements;

[0068] Polycondensation reaction: under nitrogen protection, add bio-based diol and bio-based dibasic acid into the reactor in a certain proportion, heat to an appropriate temperature (usually 180-220°C), add an appropriate amount of catalyst (such as titanate catalyst), and carry out polycondensation reaction until the target molecular weight (2000-4000g / mol) and hydroxyl value (45-55mgKOH / g) are reached;

[0069] Post-treatment: After the reaction is completed, the temperature is lowered, the material is discharged, and post-treatments such as filtration and degassing are performed to obtain bio-based polyester polyols;

[0070] Preparation of silane coupling agent grafted nanocellulose whiskers:

[0071] Dispersion: Disperse the nanocellulose whiskers evenly in the ethanol solution;

[0072] Grafting reaction: add appropriate amount of silane coupling agent, react at 90-110℃ for 3-5 hours, and control the grafting rate at 8%-12%;

[0073] Washing and drying: After the reaction is completed, the product is washed with ethanol to remove the unreacted silane coupling agent, and then dried to obtain the nanocellulose whiskers grafted with the silane coupling agent;

[0074] 2nd)TPU synthesis

[0075] Pre-polymerization:

[0076] Mixing: adding the measured bio-based polyester polyol and aliphatic diisocyanate (such as hexamethylene diisocyanate or its variant) into the reactor, controlling the NCO / OH molar ratio between 1.05:1 and 1.15:1;

[0077] Reaction: Under nitrogen protection, heat to an appropriate temperature (usually 70-90°C) to carry out prepolymerization reaction until the predetermined NCO content is reached;

[0078] Chain extension and cross-linking:

[0079] Adding chain extender: When the prepolymerization reaction reaches the predetermined stage, add a measured chain extender (such as 1,4-butanediol, 1,6-hexanediol) and continue the reaction;

[0080] Adding catalysts and additives: Adding bio-based organic tin catalysts (such as dimethyltin dilaurate, dibutyltin dilaurate) and antioxidants (such as tea polyphenols, vitamin E) at the same time to promote the reaction and improve product performance;

[0081] End point control: Control the reaction end point by monitoring the viscosity or NCO content of the reaction system;

[0082] Post-processing:

[0083] Degassing: After the reaction is completed, vacuum degassing is performed to remove the gas and small molecular by-products produced in the reaction;

[0084] Cooling and pelletizing: After the reaction product is cooled to an appropriate temperature, it is cut into pellets by a pelletizer to obtain an environmentally friendly aliphatic TPU elastic plastic product;

[0085] 3rd) Quality inspection and packaging

[0086] Quality testing: Conduct performance tests on finished products, including tensile strength, elongation at break, hardness, heat resistance and other indicators to ensure that the products meet the design requirements;

[0087] Packaging and storage: Pack qualified products into warehouses, protect them from moisture and sunlight, and store them in a cool and dry place.

[0088] Example 1

[0089] Raw material ratio:

[0090] Bio-based polyester polyol: 62 parts (molecular weight 3000g / mol, hydroxyl value 50mgKOH / g)

[0091] Aliphatic diisocyanate (hexamethylene diisocyanate): 27 parts

[0092] Silane coupling agent grafted nanocellulose whiskers: 6 parts (grafting rate 10%)

[0093] Chain extender (1,4-butanediol): 2 parts

[0094] Bio-based organotin catalyst (dimethyltin dilaurate): 0.7 parts (activity index 1.0)

[0095] Antioxidant (Tea Polyphenols): 0.5 parts

[0096] Production process:

[0097] Preparation of bio-based polyester polyols: corn sugar alcohol and succinic acid were selected as raw materials, the polycondensation temperature was 200°C, the catalyst dosage was 0.5% (based on the total weight of the raw materials), and the reaction was carried out to a molecular weight of 3000 g / mol and a hydroxyl value of 50 mgKOH / g.

[0098] Preparation of nanocellulose whiskers grafted with silane coupling agent: dispersed in ethanol, grafting reaction temperature 100°C, time 4 hours.

[0099] TPU synthesis: prepolymerization temperature is 80℃, chain extender and catalyst are added during chain extension and crosslinking, endpoint control is monitored by NCO content, degassing is performed after the reaction is completed, and pelletizing is performed after cooling to room temperature.

[0100] Performance Test:

[0101] Tensile strength: 35MPa

[0102] Elongation at break: 450%

[0103] Hardness (Shore A): 85

[0104] Heat resistance (heat deformation temperature): 70℃

[0105] Example 2

[0106] Raw material ratio:

[0107] Bio-based polyester polyol: 65 parts (molecular weight 4000g / mol, hydroxyl value 48mgKOH / g)

[0108] Aliphatic diisocyanate (trimer of hexamethylene diisocyanate): 25 parts

[0109] Silane coupling agent grafted nanocellulose whiskers: 8 parts (grafting rate 12%)

[0110] Chain extender (1,6-hexanediol): 1.8 parts

[0111] Bio-based organotin catalyst (dibutyltin dilaurate): 0.9 parts (activity index 1.1)

[0112] Antioxidant (Vitamin E): 0.7 parts

[0113] Production process:

[0114] Preparation of bio-based polyester polyols: soybean oil alcohol and glutaric acid were selected as raw materials, the polycondensation temperature was 220°C, the catalyst dosage was 0.3%, and the reaction was carried out to a molecular weight of 4000 g / mol and a hydroxyl value of 48 mgKOH / g.

[0115] TPU synthesis: prepolymerization temperature is 75℃, chain extender and catalyst are added during chain extension and crosslinking, endpoint control is achieved through viscosity monitoring, degassing after the reaction is completed, cooling to room temperature and pelletizing.

[0116] Performance Test:

[0117] Tensile strength: 38MPa

[0118] Elongation at break: 420%

[0119] Hardness (Shore A): 88

[0120] Heat resistance (heat deformation temperature): 72°C

[0121] Example 3

[0122] Raw material ratio:

[0123] Bio-based polyester polyol: 60 parts (molecular weight 2500g / mol, hydroxyl value 52mgKOH / g)

[0124] Aliphatic diisocyanate (allophanate prepolymer of hexamethylene diisocyanate): 28 parts

[0125] Silane coupling agent grafted nanocellulose whiskers: 5 parts (grafting rate 8%)

[0126] Chain extender (half 1,4-butanediol and half 1,6-hexanediol): 2 parts

[0127] Bio-based organotin catalyst (half dimethyltin dilaurate and half dibutyltin dilaurate): 0.6 parts (average activity index 1.05)

[0128] Antioxidants (half tea polyphenols and half vitamin E): 0.4 parts

[0129] Production process:

[0130] Preparation of bio-based polyester polyols: diols from sugarcane and dibasic acids from biological fermentation were selected as raw materials, the polycondensation reaction temperature was 190°C, the catalyst dosage was 0.4%, and the reaction was carried out to a molecular weight of 2500 g / mol and a hydroxyl value of 52 mgKOH / g.

[0131] TPU synthesis: prepolymerization temperature is 85℃, chain extender and catalyst are added during chain extension and crosslinking, endpoint control is achieved through dual monitoring of NCO content and viscosity, degassing is performed after the reaction is completed, and pelletizing is performed after cooling to room temperature.

[0132] Performance Test:

[0133] Tensile strength: 36MPa

[0134] Elongation at break: 430%

[0135] Hardness (Shore A): 86

[0136] Heat resistance (heat deformation temperature): 71°C

[0137] Comparative Example

[0138] Raw material ratio:

[0139] Traditional polyester polyol (non-biobased): 65 parts (molecular weight 3000g / mol, hydroxyl value 50mgKOH / g)

[0140] Aliphatic diisocyanate (hexamethylene diisocyanate): 27 parts

[0141] No nanocellulose whiskers added

[0142] Chain extender (1,4-butanediol): 2 parts

[0143] Organotin catalyst (non-bio-based): 0.7 parts

[0144] Antioxidant (common commercial antioxidant): 0.5 parts

[0145] Production process:

[0146] Conventional polyester polyols are used directly without the need for preparation steps.

[0147] The TPU synthesis process is similar to that of the embodiment, but without the addition of nanocellulose whiskers.

[0148] Performance Test:

[0149] Tensile strength: 32MPa

[0150] Elongation at break: 400%

[0151] Hardness (Shore A): 84

[0152] Heat resistance (heat deformation temperature): 68℃.

[0153] Comparative Analysis

[0154] When comparing the TPU prepared from the conventional non-bio-based polyester polyol with the environmentally friendly aliphatic TPU elastic plastic in the examples, we can observe significant performance differences and environmental advantages;

[0155] 1. Mechanical properties

[0156] Tensile strength: The tensile strength of TPU in the examples is generally higher than that in the control examples, which is mainly attributed to the use of bio-based polyester polyols and the reinforcing effect of nanocellulose whiskers. Since bio-based polyester polyols are derived from renewable resources, their molecular structure may be different from that of traditional polyesters, thus affecting the mechanical properties of TPU. Nanocellulose whiskers, as a high-performance nanofiller, can significantly improve the tensile strength of TPU;

[0157] Elongation at break: The elongation at break of the TPU in the examples also showed a higher value, which may be due to the synergistic effect of the bio-based polyester polyol and the nanocellulose whiskers, which made the interaction between the TPU molecular chains more compact, thereby improving its toughness and elongation at break;

[0158] Hardness: The hardness of the TPU in the example is slightly higher than that in the comparative example, which may be due to the more precise control of the molecular weight distribution and hydroxyl value of the bio-based polyester polyol and the reinforcing effect of the nanocellulose whiskers. The increase in hardness contributes to the wear resistance and compression resistance of TPU in applications such as footwear.

[0159] 2. Heat resistance

[0160] Heat deformation temperature: The heat deformation temperature of TPU in the examples is generally higher than that in the comparative examples, which indicates that the addition of bio-based polyester polyol and nanocellulose whiskers improves the thermal stability of TPU. The increase in heat deformation temperature helps the application performance of TPU in high temperature environments.

[0161] 3. Environmental advantages

[0162] Source of raw materials: The TPU in the embodiment uses raw materials such as bio-based polyester polyols and chain extenders derived from renewable resources, which helps to reduce dependence on fossil resources, reduce carbon emissions, and conform to the concept of sustainable development;

[0163] Degradability: Although TPU itself is not completely degradable, the use of bio-based raw materials makes it easier to be decomposed by microorganisms after disposal, thereby reducing pollution to the environment;

[0164] Nanocellulose whiskers: As a natural polymer material, nanocellulose whiskers are renewable, degradable and environmentally friendly. Their addition not only improves the performance of TPU, but also further enhances its environmental attributes.

[0165] 4. Production process

[0166] Reaction conditions: The TPU production process in the embodiment adopts milder reaction conditions, such as lower polycondensation temperature and prepolymerization temperature, which helps to reduce energy consumption and reduce the generation of harmful substances;

[0167] Catalyst selection: The use of bio-based organotin catalysts not only improves reaction efficiency, but also reduces environmental pollution problems that may be caused by traditional catalysts;

[0168] In summary, the environmentally friendly aliphatic TPU elastic plastic in the embodiment shows better performance than the comparative example in terms of mechanical properties, heat resistance and environmental advantages, which is mainly due to the use of bio-based raw materials and the reinforcing effect of nanocellulose whiskers. Therefore, the environmentally friendly TPU has broad market prospects and potential economic value in applications such as shoe materials.

[0169] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. An environmentally friendly aliphatic TPU elastic plastic, characterized in that: The elastic plastic comprises, by weight, 60-65 parts of bio-based polyester polyol, 25-30 parts of aliphatic diisocyanate, 5-8 parts of nanocellulose whiskers grafted with a silane coupling agent, 1.5-2.5 parts of a chain extender, 0.5-1 parts of a bio-based organic tin catalyst, and 0.3-0.7 parts of an antioxidant; Among them, the molecular weight range of bio-based polyester polyols is 2000-4000g / mol, and the hydroxyl value is 45-55mgKOH / g; The grafting rate of silane coupling agent is 8%-12%; The activity index of bio-based organotin catalysts is 0.9-1.

1.

2. The environmentally friendly aliphatic TPU elastic plastic according to claim 1, characterized in that: The bio-based polyester polyol is prepared by polycondensation of bio-based diol and bio-based dibasic acid.

3. The environmentally friendly aliphatic TPU elastic plastic according to claim 1, characterized in that: The length of the nanocellulose whisker is 100-150nm and the diameter is 10-15nm.

4. The environmentally friendly aliphatic TPU elastic plastic according to claim 1, characterized in that: The molar ratio of NCO / OH in the aliphatic diisocyanate and the bio-based polyester polyol is between 1.05:1 and 1.15:

1.

5. The environmentally friendly aliphatic TPU elastic plastic according to claim 1, characterized in that: The silane coupling agent grafted nanocellulose whiskers are prepared by dispersing the nanocellulose whiskers in an ethanol solution and then adding the silane coupling agent for reaction. The reaction temperature is 90-110° C. and the reaction time is 3-5 hours.

6. The environmentally friendly aliphatic TPU elastic plastic according to claim 1, characterized in that: The aliphatic diisocyanate is hexamethylene diisocyanate, or an aqueous dispersion of hexamethylene diisocyanate, or a trimer of hexamethylene diisocyanate, or an allophanate prepolymer of hexamethylene diisocyanate.

7. The environmentally friendly aliphatic TPU elastic plastic according to claim 1, characterized in that: The chain extender is one or more of 1,4-butanediol and 1,6-hexanediol.

8. The environmentally friendly aliphatic TPU elastic plastic according to claim 1, characterized in that: The antioxidant is one or more of tea polyphenols and vitamin E.

9. The environmentally friendly aliphatic TPU elastic plastic according to claim 1, characterized in that: The bio-based organic tin catalyst is one or more of dimethyltin dilaurate and dibutyltin dilaurate.