High-moisture-permeability TPU (thermoplastic polyurethane) film

Abstract

The invention relates to a high-moisture-permeability TPU (thermoplastic polyurethane) film, which relates to the field of film materials and comprises the following components in parts by mass: 100 parts of polyurethane, 0.5-1 part of an antioxidant, 0.5-1.5 parts of a lubricant and 5-15 parts of a pore forming agent, the polyurethane is prepared by the following steps: dehydrating polyether polyol, adding diisocyanate and a catalyst, heating, stirring and reacting, adding a chain extender, heating, stirring and reacting to obtain the polyurethane. The TPU film has the effect of improving the moisture permeability and tear resistance of the TPU film.

Description

Technical Field

[0001] This application relates to the field of thin film materials, and in particular to a high moisture permeability TPU film. Background Technology

[0002] In the field of materials science and engineering, thermoplastic polyurethane (TPU) film, as an important functional film material, has received widespread attention and application in recent years. With the continuous development of industry, TPU film, due to its excellent physical properties such as good elasticity, abrasion resistance, oil resistance, and biocompatibility, is widely used in clothing, medical, electronics, construction, and other fields. In the clothing industry, TPU film can be used to make waterproof and breathable outdoor clothing, improving wearing comfort; in the medical field, it can be used to make wound dressings to promote wound healing; in the electronics field, it can be used as a protective film for displays, providing scratch and abrasion resistance. These applications have not only driven the development of related industries but also brought many conveniences to people's lives.

[0003] In existing technologies, the commonly used methods to improve certain properties of TPU membranes, such as moisture permeability, are mainly chemical modification and physical modification. Chemical modification improves performance by altering the molecular structure of TPU. Specifically, it involves introducing specific chemical groups during TPU synthesis to adjust its crystallinity and intermolecular forces. This method fundamentally changes the chemical properties of TPU, thereby improving membrane performance. Physical modification achieves its purpose by adding various additives, such as filling with nanoscale inorganic particles or organic fibers. These additives can form microscopic channels or network structures within the TPU membrane, facilitating water vapor transport and thus improving moisture permeability.

[0004] However, these existing methods still have significant limitations. While chemical modification can alter the structure of TPU at the molecular level, it often leads to changes in other membrane properties, such as reduced strength and toughness. Furthermore, chemical modification processes are relatively complex and costly. Physical modification methods may introduce additives that aggregate within the membrane, disrupting its uniformity and affecting the stability of its moisture permeability. Simultaneously, TPU membranes prepared using these methods often exhibit low moisture permeability, failing to meet the demands of applications requiring high moisture permeability. Therefore, improvements are needed. Summary of the Invention

[0005] To improve the moisture permeability of TPU membranes, this application provides a high moisture permeability TPU membrane.

[0006] The high moisture permeability TPU membrane provided in this application adopts the following technical solution:

[0007] A high moisture permeability TPU membrane, the raw materials for which are prepared include the following components in parts by weight:

[0008] 100 parts of polyurethane

[0009] Antioxidant 0.5-1 part

[0010] 0.5-1.5 parts lubricant

[0011] 5-15 parts of pore-forming agent;

[0012] The polyurethane is prepared using the following steps:

[0013] Polyether polyol is dehydrated, diisocyanate and catalyst are added, and the mixture is heated and stirred to react. Then, a chain extender is added, and the mixture is heated and stirred to react again to obtain polyurethane.

[0014] The pore-forming agent forms microporous channels in the polyurethane matrix, constructing a water vapor diffusion path. The polyurethane is generated by reacting polyether polyol with diisocyanate to form a prepolymer, and then the molecular chain is extended by a chain extender to form a regular hard-segment-soft-segment microphase separation structure. This structure can maintain the stability of the micropore morphology and enhance hydrophilicity through soft-segment ether bonds, synergistically promoting the efficient transport of water molecules along the microporous channels, ultimately endowing the membrane with long-lasting high moisture permeability.

[0015] Preferably, the diisocyanate comprises 1,4-cyclohexane diisocyanate.

[0016] The rigid alicyclic structure of 1,4-cyclohexane diisocyanate forms regular hard-segment microregions in the polyurethane molecular chain, enhancing tear resistance by strengthening the intermolecular forces. The hydrophobic properties of this alicyclic structure and the strong hydrophilicity of the soft-segment polyether create more significant microphase separation, driving water molecules to diffuse directionally along the hydrophilic soft-segment enrichment region. The micropores generated by the pore-forming agent maintain a stable pore structure under the support of the rigid alicyclic structure. This dual mechanism synergistically achieves a simultaneous improvement in moisture permeability and tear resistance.

[0017] Preferably, the chain extender comprises diethylene glycol ethyl ether.

[0018] The ether bonds in the diethylene glycol ether molecular chain enhance the hydrophilicity of the soft segment, promoting the adsorption and diffusion of water molecules along the polyether chain; the flexible ether bonds extend the molecular chain entanglement distance, forming an energy dissipation network in the microphase separation structure; the urethane groups formed by chain extension form strong hydrogen bond crosslinks with the rigid structure of the hard segment, which not only maintains the stability of the microporous channels to ensure moisture permeability, but also enhances the material's deformation ability under tear stress through a reversible bonding mechanism, thereby improving the moisture permeability and tear resistance of the TPU film.

[0019] Preferably, the polyether polyol is prepared by modification using the following steps:

[0020] The polyether polyol was dehydrated, and under a protective atmosphere, citric acid and tetrabutyl titanate were added. The mixture was heated and stirred to react, then cooled. 2-aminoethanol was added, and after the addition was complete, the mixture was heated and stirred to react. After the reaction was complete, diatomaceous earth and activated carbon were added, and the mixture was heated and stirred before filtration to obtain hyperbranched polyether polyol.

[0021] The polyether polyol undergoes hyperbranching modification, forming a dense branched network through citric acid and tetrabutyl titanate catalysis. A terminal primary amine group is then introduced via a reaction with 2-aminoethanol, enhancing the hydrophilicity of the polyether soft segments and strengthening molecular chain entanglement. Diatomaceous earth and activated carbon are used for purification to eliminate byproducts. When the hyperbranched polyether polyol reacts with diisocyanate, a more regular hard-segment-soft-segment microphase separation is formed. The highly branched soft segments construct continuous water molecule transport channels, while rigid branched nodes crosslink with chain extenders to form an energy dissipation network. This maintains high moisture permeability while resisting tearing stress through molecular chain slippage and bonding recombination mechanisms, thereby improving the moisture permeability and tear resistance of the TPU membrane.

[0022] Preferably, the mass ratio of the polyether polyol, citric acid and 2-aminoethanol is 1:0.1:(0.16-0.22).

[0023] The hyperbranched polyether polyol prepared according to the above mass ratio can effectively improve the moisture permeability and tear resistance of TPU film.

[0024] Preferably, the raw materials for preparation also include mesoporous silica microspheres.

[0025] Preferably, the amount of mesoporous silica microspheres added is 1-2 parts.

[0026] The nanoscale pores of mesoporous silica microspheres construct secondary pathways for water molecule transport within the polyurethane matrix, synergistically forming a hierarchical moisture-permeable network with the micron-scale pores created by the pore-forming agent, thereby improving water vapor diffusion efficiency. Its rigid inorganic framework serves as a physical crosslinking point, enhancing inter-chain forces through interfacial stress transfer. Under tearing stress, it induces craze orientation and crack passivation, while maintaining the stability of the microporous structure, thus improving the moisture permeability and tear resistance of the TPU film.

[0027] Preferably, the mesoporous silica microspheres are prepared by modification treatment using the following steps:

[0028] Mesoporous silica microspheres were added to a solvent, sonicated, and then octadecyltrimethoxysilane and perfluorooctyltriethoxysilane were added. The pH was adjusted to acidic, and the mixture was heated and stirred under a protective atmosphere. After centrifugation, washing, and drying, modified mesoporous silica microspheres were obtained.

[0029] Mesoporous silica microspheres are gradient-bonded with octadecyltrimethoxysilane and perfluorooctyltriethoxysilane under acidic conditions to form a hydrophobic-superhydrophobic block modification layer. This special interface structure selectively allows water vapor to pass through the mesoporous channels efficiently while repelling liquid water from blocking the channels, thus improving moisture permeability. At the same time, the long-chain alkyl groups of the bissilane and the perfluorinated chains form an interpenetrating network in the polyurethane matrix. Through the synergistic effect of the rigid mesoporous framework and the flexible organic chains, stress is efficiently transferred and dispersed at the inorganic-organic interface, inducing molecular chain slippage to dissipate energy and inhibiting crack propagation. This constructs a multidimensional tear-resistant barrier while maintaining the stability of the hierarchical moisture permeability network.

[0030] Preferably, the mass ratio of the mesoporous silica microspheres, octadecyltrimethoxysilane, and perfluorooctyltriethoxysilane is 1:0.15:(0.03-0.05).

[0031] The modified mesoporous silica microspheres prepared according to the above mass ratio can effectively improve the moisture permeability and tear resistance of TPU films.

[0032] Preferably, the pore-forming agent comprises azodicarbonamide.

[0033] In summary, this application includes at least one of the following beneficial technical effects:

[0034] The pore-forming agent forms microporous channels in the polyurethane matrix, constructing a water vapor diffusion path. The polyurethane is generated by reacting polyether polyol with diisocyanate to form a prepolymer, and then the molecular chain is extended by a chain extender to form a regular hard-segment-soft-segment microphase separation structure. This structure can maintain the stability of the micropore morphology and enhance hydrophilicity through soft-segment ether bonds, synergistically promoting the efficient transport of water molecules along the microporous channels, ultimately endowing the membrane with long-lasting high moisture permeability.

[0035] The polyether polyol undergoes hyperbranching modification, forming a dense branched network through citric acid and tetrabutyl titanate catalysis. A terminal primary amine group is then introduced via a reaction with 2-aminoethanol, enhancing the hydrophilicity of the polyether soft segments and strengthening molecular chain entanglement. Diatomaceous earth and activated carbon are used for purification to eliminate byproducts. When the hyperbranched polyether polyol reacts with diisocyanate, a more regular hard-segment-soft-segment microphase separation is formed. The highly branched soft segments construct continuous water molecule transport channels, while rigid branched nodes crosslink with chain extenders to form an energy dissipation network. This maintains high moisture permeability while resisting tearing stress through molecular chain slippage and bonding recombination mechanisms, thereby improving the moisture permeability and tear resistance of the TPU membrane.

[0036] Mesoporous silica microspheres are gradient-bonded with octadecyltrimethoxysilane and perfluorooctyltriethoxysilane under acidic conditions to form a hydrophobic-superhydrophobic block modification layer. This special interface structure selectively allows water vapor to pass through the mesoporous channels efficiently while repelling liquid water from blocking the channels, thus improving moisture permeability. At the same time, the long-chain alkyl groups of the bissilane and the perfluorinated chains form an interpenetrating network in the polyurethane matrix. Through the synergistic effect of the rigid mesoporous framework and the flexible organic chains, stress is efficiently transferred and dispersed at the inorganic-organic interface, inducing molecular chain slippage to dissipate energy and inhibiting crack propagation. This constructs a multidimensional tear-resistant barrier while maintaining the stability of the hierarchical moisture permeability network. Detailed Implementation

[0037] This application discloses a high moisture permeability TPU film. Unless otherwise specified, all raw materials used in this application are commercially available. The following detailed description, in conjunction with embodiments, further illustrates this application:

[0038] Raw material specifications: Polyether polyol, model 330N, purchased from Shandong Shengteng Chemical Co., Ltd.; 1,4-cyclohexane diisocyanate (CAS No.: 2556-36-7); bismorpholino diethyl ether (CAS No.: 6425-39-4); diethylene glycol ethyl ether (CAS No.: 111-90-0); azodicarbonamide (CAS No.: 123-77-3); Irgafos Item 168 was purchased from Shanghai Jingyan Chemical Co., Ltd., MB50-002 was purchased from Shanghai Kaiyin Chemical Co., Ltd., citric acid (CAS No.: 77-92-9), tetrabutyl titanate (CAS No.: 5593-70-4), 2-aminoethanol (CAS No.: 141-43-5), mesoporous silica microspheres (item number 101014) were purchased from Jiangsu Xianfeng Nanomaterials Technology Co., Ltd., octadecyltrimethoxysilane (CAS No.: 3069-42-9), and perfluorooctyltriethoxysilane (CAS No.: 51851-37-7).

[0039] Example 1

[0040] Preparation of high moisture permeability TPU membrane

[0041] The diisocyanate is 1,4-cyclohexane diisocyanate, the chain extender is diethylene glycol ethyl ether, the pore-forming agent is azodicarbonamide, the antioxidant is Irgafos 168, the lubricant is MB50-002, and the catalyst is bismorpholino diethyl ether.

[0042] 100 parts of polyether polyol were dehydrated at 110℃ and under vacuum of -0.095MPa for 2 hours, then protected with nitrogen gas. After cooling to 80℃, 45 parts of 1,4-cyclohexane diisocyanate and 0.25 parts of catalyst were added, and the mixture was stirred at 200 rpm for 2 hours. Then, 10 parts of diethylene glycol ethyl ether were added, and the mixture was stirred at 95℃ and 200 rpm for 2 hours to obtain polyurethane.

[0043] Add 0.5 parts antioxidant, 0.5 parts lubricant and 5 parts pore-forming agent to 80 parts polyurethane. Under a nitrogen atmosphere, heat to 185°C and stir at 50 rpm for 10 min. Then heat to 205°C and stir at 30 rpm for 3 min. After casting and winding, a high moisture-permeable TPU film is obtained.

[0044] Example 2

[0045] Preparation of high moisture permeability TPU membrane

[0046] The diisocyanate is 1,4-cyclohexane diisocyanate, the chain extender is diethylene glycol ethyl ether, the pore-forming agent is azodicarbonamide, the antioxidant is Irgafos 168, the lubricant is MB50-002, and the catalyst is bismorpholino diethyl ether.

[0047] 100 parts of polyether polyol were dehydrated at 110℃ and under vacuum of -0.095MPa for 2 hours, then protected with nitrogen gas. After cooling to 80℃, 45 parts of 1,4-cyclohexane diisocyanate and 0.25 parts of catalyst were added, and the mixture was stirred at 200 rpm for 2 hours. Then, 10 parts of diethylene glycol ethyl ether were added, and the mixture was stirred at 95℃ and 200 rpm for 2 hours to obtain polyurethane.

[0048] Add 1 part antioxidant, 1.5 parts lubricant and 15 parts pore-forming agent to 100 parts polyurethane. Under a nitrogen atmosphere, heat to 185°C and stir at 50 rpm for 10 min. Then heat to 205°C and stir at 30 rpm for 3 min. After casting and winding, a high moisture-permeable TPU film is obtained.

[0049] Example 3

[0050] Preparation of high moisture permeability TPU membrane

[0051] The diisocyanate is 1,4-cyclohexane diisocyanate, the chain extender is diethylene glycol ethyl ether, the pore-forming agent is azodicarbonamide, the antioxidant is Irgafos 168, the lubricant is MB50-002, and the catalyst is bismorpholino diethyl ether.

[0052] 100 parts of polyether polyol were dehydrated at 110℃ and under vacuum of -0.095MPa for 2 hours, then protected with nitrogen gas. After cooling to 80℃, 45 parts of 1,4-cyclohexane diisocyanate and 0.25 parts of catalyst were added, and the mixture was stirred at 200 rpm for 2 hours. Then, 10 parts of diethylene glycol ethyl ether were added, and the mixture was stirred at 95℃ and 200 rpm for 2 hours to obtain polyurethane.

[0053] Add 0.75 parts antioxidant, 1 part lubricant and 10 parts pore-forming agent to 90 parts polyurethane. Under nitrogen atmosphere, heat to 185°C and stir at 50 rpm for 10 min. Heat to 205°C and stir at 30 rpm for 3 min. After casting and winding, a high moisture-permeable TPU film is obtained.

[0054] Example 4

[0055] Example 4 is based on Example 3. The only difference between Example 4 and Example 3 is that the polyether polyol in Example 4 has been modified. It is prepared using the following steps:

[0056] The polyether polyol was dehydrated at 110℃ and -0.09MPa under vacuum until the water content was less than 0.05%. Under nitrogen protection, citric acid and tetrabutyl titanate were added, and the mixture was stirred at 180℃ for 6 hours at a speed of 500 rpm. The temperature was then lowered to 30℃, and 2-aminoethanol was added dropwise under ice bath conditions. The mass ratio of polyether polyol, citric acid, and 2-aminoethanol was 1:0.1:0.16, and the addition was completed within 2 hours. The temperature was then raised to 55℃ and the mixture was stirred at a speed of 400 rpm until the acid value was less than 2 mg KOH / g. Diatomaceous earth and activated carbon were added, and the mixture was stirred at 80℃ for 30 minutes at a speed of 200 rpm. The mixture was then filtered to obtain hyperbranched polyether polyol.

[0057] Example 5

[0058] Example 5 is based on Example 4. The only difference between Example 5 and Example 4 is that the mass ratio of polyether polyol, citric acid and 2-aminoethanol in Example 5 is 1:0.1:0.22.

[0059] Example 6

[0060] Example 6 is based on Example 4. The only difference between Example 6 and Example 4 is that the mass ratio of polyether polyol, citric acid and 2-aminoethanol in Example 6 is 1:0.1:0.19.

[0061] Example 7

[0062] Example 7 is based on Example 4. The only difference between Example 7 and Example 4 is that the mass ratio of polyether polyol, citric acid and 2-aminoethanol in Example 7 is 1:0.1:0.12.

[0063] Example 8

[0064] Example 8 is based on Example 4. The only difference between Example 8 and Example 4 is that the mass ratio of polyether polyol, citric acid and 2-aminoethanol in Example 8 is 1:0.1:0.26.

[0065] Example 9

[0066] Example 9 is based on Example 3. The only difference between Example 9 and Example 3 is that the raw materials prepared in Example 9 also include 1 part of mesoporous silica microspheres.

[0067] Preparation of high moisture permeability TPU membrane

[0068] The diisocyanate is 1,4-cyclohexane diisocyanate, the chain extender is diethylene glycol ethyl ether, the pore-forming agent is azodicarbonamide, the antioxidant is Irgafos 168, the lubricant is MB50-002, and the catalyst is bismorpholino diethyl ether.

[0069] 100 parts of polyether polyol were dehydrated at 110℃ and under vacuum of -0.095MPa for 2 hours, then protected with nitrogen gas. After cooling to 80℃, 45 parts of 1,4-cyclohexane diisocyanate and 0.25 parts of catalyst were added, and the mixture was stirred at 200 rpm for 2 hours. Then, 10 parts of diethylene glycol ethyl ether were added, and the mixture was stirred at 95℃ and 200 rpm for 2 hours to obtain polyurethane.

[0070] Add 0.75 parts antioxidant, 1 part lubricant and 10 parts pore-forming agent to 90 parts polyurethane. Under a nitrogen atmosphere, heat to 185°C and stir at 50 rpm for 5 minutes. Add 1 part mesoporous silica microspheres and disperse at 80 rpm for 5 minutes. Heat to 205°C and stir at 30 rpm for 3 minutes. After casting and winding, a high moisture permeability TPU film is obtained.

[0071] Example 10

[0072] Example 10 is based on Example 9. The only difference between Example 10 and Example 9 is that 2 parts of mesoporous silica microspheres are added in Example 10.

[0073] Example 11

[0074] Example 11 is based on Example 9. The only difference between Example 11 and Example 9 is that 1.5 parts of mesoporous silica microspheres are added in Example 11.

[0075] Example 12

[0076] Example 12 is based on Example 9. The only difference between Example 12 and Example 9 is that 4 parts of mesoporous silica microspheres are added in Example 12.

[0077] Example 13

[0078] Example 13 is based on Example 9. The only difference between Example 13 and Example 9 is that the mesoporous silica microspheres in Example 13 have undergone modification treatment and are prepared using the following steps:

[0079] Mesoporous silica microspheres were added to toluene at a solid-liquid ratio of 1:10. After sonication for 30 min, octadecyltrimethoxysilane and perfluorooctyltriethoxysilane were added, with a mass ratio of 1:0.15:0.03. The pH was adjusted to 4 using glacial acetic acid. Under nitrogen protection, the mixture was stirred and refluxed at 110 °C at 500 rpm for 6 h. After centrifugation, washing with deionized water, and vacuum drying at 80 °C, modified mesoporous silica microspheres were obtained.

[0080] Example 14

[0081] Example 14 is based on Example 13. The only difference between Example 14 and Example 13 is that the mass ratio of mesoporous silica microspheres, octadecyltrimethoxysilane and perfluorooctyltriethoxysilane in Example 14 is 1:0.15:0.05.

[0082] Example 15

[0083] Example 15 is based on Example 13. The only difference between Example 15 and Example 13 is that the mass ratio of mesoporous silica microspheres, octadecyltrimethoxysilane and perfluorooctyltriethoxysilane in Example 15 is 1:0.15:0.04.

[0084] Example 16

[0085] Example 16 is based on Example 13. The only difference between Example 16 and Example 13 is that the mass ratio of mesoporous silica microspheres, octadecyltrimethoxysilane and perfluorooctyltriethoxysilane in Example 16 is 1:0.15:0.01.

[0086] Example 17

[0087] Example 17 is based on Example 13. The only difference between Example 17 and Example 13 is that the mass ratio of mesoporous silica microspheres, octadecyltrimethoxysilane and perfluorooctyltriethoxysilane in Example 17 is 1:0.15:0.07.

[0088] Comparative Example 1

[0089] Comparative Example 1 is based on Example 3. The only difference between Comparative Example 1 and Example 3 is that no pore-forming agent is added in Comparative Example 1.

[0090] Preparation of high moisture permeability TPU membrane

[0091] The diisocyanate is 1,4-cyclohexane diisocyanate, the chain extender is diethylene glycol ethyl ether, the pore-forming agent is azodicarbonamide, the antioxidant is Irgafos 168, the lubricant is MB50-002, and the catalyst is bismorpholino diethyl ether.

[0092] 100 parts of polyether polyol were dehydrated at 110℃ and under vacuum of -0.095MPa for 2 hours, then protected with nitrogen gas. After cooling to 80℃, 45 parts of 1,4-cyclohexane diisocyanate and 0.25 parts of catalyst were added, and the mixture was stirred at 200 rpm for 2 hours. Then, 10 parts of diethylene glycol ethyl ether were added, and the mixture was stirred at 95℃ and 200 rpm for 2 hours to obtain polyurethane.

[0093] Add 0.75 parts antioxidant and 1 part lubricant to 90 parts polyurethane, heat to 185°C under nitrogen atmosphere and stir at 50 rpm for 15 minutes. After casting and winding, a high moisture permeability TPU film is obtained.

[0094] Performance testing

[0095] (1) The standard GB / T 1037-1988 Test method for water vapor permeability of plastic films and sheets (cup method) was selected. The moisture permeability of the samples was calculated by using the cup method. Each sample was tested three times, and the average value was taken after measurement. The results are recorded in Table 1.

[0096] (2) Select GB / T 16578.1 Determination of tear resistance of plastic films and sheets - Part 1: Pants tear test as the standard, test the tear strength of the test specimens, prepare five samples for each test specimen, take the average value after measurement, and record the results in Table 1.

[0097] Table 1. Test results of water permeability and tear strength of TPU film Test results Moisture permeability (g / (m²·24h)) Tear strength (N / mm) Example 1 7157 26 Example 2 7219 28 Example 3 7243 29 Example 4 8372 30 Example 5 8424 31 Example 6 8496 33 Example 7 7735 30 Example 8 7918 29 Example 9 7846 32 Example 10 8125 30 Example 11 7993 33 Example 12 8775 22 Example 13 8864 35 Example 14 8938 33 Example 15 9012 37 Example 16 8356 32 Example 17 8574 30 Comparative Example 1 3642 35

[0098] As shown in Table 1, the moisture permeability of Examples 1-3 is greater than 7157 g / (m²·24h) and the tear strength is greater than 26 N / mm, thus demonstrating that the high moisture permeability TPU membrane prepared in this application has good moisture permeability and tear resistance.

[0099] As shown in Table 1, the only difference between Examples 4-8 and Example 3 is that in Examples 4-6, the polyether polyol was modified according to the specified ratio, and the performance was significantly improved; in Examples 7 and 8, the optimal ratio was destroyed, and the performance improvement effect was slightly reduced.

[0100] As shown in Table 1, the only difference between Examples 9-12 and Example 3 is that: in Examples 9-11, mesoporous silica microspheres with a limited ratio range were added, resulting in improved performance; in Example 12, an excessive amount of mesoporous silica microspheres were added, which improved the moisture permeability but affected the tear strength.

[0101] As shown in Table 1, the only difference between Examples 13-17 and Example 9 is that the mesoporous silica in Examples 13-15 was further modified, resulting in a further improvement in performance; while Examples 16 and 17 disrupted the optimal modification ratio, resulting in a slight decrease in performance improvement.

[0102] As shown in Table 1, the only difference between Comparative Example 1 and Example 3 is that no pore-forming agent was added in Comparative Example 1. Compared with Example 3, the performance of Comparative Example 1 is significantly reduced. This is because without the addition of a pore-forming agent, the membrane lacks a microporous structure, resulting in a significant decrease in moisture permeability, while the strength increases.

[0103] This specific embodiment is merely an explanation of this application and is not intended to limit it. Based on the above description, those skilled in the art can make various changes and modifications without departing from the technical concept of this application. The technical scope of this application is not limited to the contents of the specification but must be determined according to the scope of the claims.

Claims

1. A high moisture permeability TPU membrane, characterized in that: The raw materials for preparation include the following components in parts by weight: 100 parts of polyurethane Antioxidant 0.5-1 part 0.5-1.5 parts lubricant 5-15 parts of pore-forming agent; The polyurethane is prepared using the following steps: Polyether polyol is dehydrated, diisocyanate and catalyst are added, and the mixture is heated and stirred to react. Then, a chain extender is added, and the mixture is heated and stirred to react again to obtain polyurethane.

2. The high moisture permeability TPU membrane according to claim 1, characterized in that: The diisocyanate includes 1,4-cyclohexane diisocyanate.

3. The high moisture permeability TPU membrane according to claim 2, characterized in that: The chain extender includes diethylene glycol ethyl ether.

4. The high moisture permeability TPU membrane according to claim 3, characterized in that: The polyether polyol was prepared by modification using the following steps: The polyether polyol was dehydrated, and under a protective atmosphere, citric acid and tetrabutyl titanate were added. The mixture was heated and stirred to react, then cooled. 2-aminoethanol was added, and after the addition was complete, the mixture was heated and stirred to react. After the reaction was complete, diatomaceous earth and activated carbon were added, and the mixture was heated and stirred before filtration to obtain hyperbranched polyether polyol.

5. The high moisture permeability TPU membrane according to claim 4, characterized in that: The mass ratio of the polyether polyol, citric acid and 2-aminoethanol is 1:0.1:(0.16-0.22).

6. The high moisture permeability TPU membrane according to claim 1, characterized in that: The raw materials used in the preparation also include mesoporous silica microspheres.

7. The high moisture permeability TPU membrane according to claim 6, characterized in that: The amount of mesoporous silica microspheres added is 1-2 parts.

8. The high moisture permeability TPU membrane according to claim 7, characterized in that: The mesoporous silica microspheres were prepared by the following steps after modification: Mesoporous silica microspheres were added to a solvent, sonicated, and then octadecyltrimethoxysilane and perfluorooctyltriethoxysilane were added. The pH was adjusted to acidic, and the mixture was heated and stirred under a protective atmosphere. After centrifugation, washing, and drying, modified mesoporous silica microspheres were obtained.

9. The high moisture permeability TPU membrane according to claim 8, characterized in that: The mass ratio of the mesoporous silica microspheres, octadecyltrimethoxysilane, and perfluorooctyltriethoxysilane is 1:0.15:(0.03-0.05).

10. A high moisture permeability TPU membrane according to claim 1, characterized in that: The pore-forming agent includes azodicarbonamide.