Thermoplastic polyurethane elastomer for a moisture permeable film and a method for preparing the same

Abstract

The application belongs to the technical field of polyurethane elastomers, and relates to a thermoplastic polyurethane elastomer for a moisture-permeable film and a preparation method thereof. 2 The general structure of the thermoplastic polyurethane elastomer for the moisture-permeable film is shown in the formula, wherein R1 is a corresponding diisocyanate part, R2 is a corresponding small-molecule diol chain extender part, R3 is x = 1-10, n = 3-15, and a = 20-30; a 15-micron-thick film prepared from the thermoplastic polyurethane elastomer for the moisture-permeable film has a moisture permeability of >10000 g / m 2 The preparation method of the thermoplastic polyurethane elastomer for the moisture-permeable film comprises the following steps: polymerizing a polyether macromolecular diol with a pyridine type ionic liquid structure, an organic diisocyanate and a small-molecule diol chain extender to prepare the thermoplastic polyurethane elastomer for the moisture-permeable film. The thermoplastic polyurethane elastomer for the moisture-permeable film has excellent moisture permeability, heat resistance and melt strength, and the preparation method is simple and easy to implement.

Description

Technical Field

[0001] This invention belongs to the field of polyurethane elastomer technology, and relates to a thermoplastic polyurethane elastomer for breathable membranes and its preparation method. Background Technology

[0002] Thermoplastic polyurethane elastomer (TPU) is a polymeric synthetic material composed of flexible and rigid segments. It exhibits rubber-like elasticity at low temperatures and can be plasticized and molded upon heating. It is generally synthesized from diisocyanates, macromolecular diols, and small-molecule chain extenders. Its flexible molecular structure design allows TPU to achieve versatility and meet diverse application requirements.

[0003] TPU waterproof and breathable fabric is made by laminating a layer of TPU film with waterproof and breathable properties onto the surface of traditional textile fabric. The TPU film is a non-porous film that prevents dripping water from passing through. At the same time, the TPU molecular structure contains a certain amount of hydrophilic groups. These groups first "capture" water vapor molecules emitted by the human body through hydrophilic interaction. Due to the thermal motion of the elastomer macromolecular chains, instantaneous gaps are formed between the molecular chains. Coupled with the driving force of the water vapor pressure difference between the inside and outside of the membrane, water vapor molecules are transferred along the gaps between the dense molecular chains from the side with higher vapor pressure to the other side, that is, from the side in contact with the skin to the surrounding environment, thus achieving the purpose of moisture permeability.

[0004] The moisture permeability of TPU is mainly determined by its soft segments. To achieve high moisture permeability, the TPU molecular chain needs a higher proportion of soft segments, but this lowers its melting point. Currently, the melting point of TPU used in high-permeability membranes is generally below 150℃. In special applications such as high-temperature protective clothing, the melting point of TPU waterproof and breathable membranes needs to be increased to above 200℃. This requires lowering the proportion of soft segments, but this leads to a significant reduction in moisture permeability, failing to meet the requirements.

[0005] Using high molecular weight (number average molecular weight ≥ 2000 Daltons) macromolecular diols as soft segments to synthesize TPU can achieve a higher melting point. However, the long molecular chains of these high molecular weight diols make them prone to orientation and crystallization during blow molding and extrusion, restricting the movement of the soft segment molecular chains and failing to effectively improve moisture permeability. Furthermore, high-melting-point TPU requires higher processing temperatures, which weakens the intermolecular chain forces during processing, leading to slippage, reduced melt strength, and a narrow processing temperature window. Therefore, poor moisture permeability and a narrow processing window limit the application of high heat-resistant TPU with melting points above 200℃ in the field of waterproof and breathable membranes.

[0006] To address the aforementioned problems, existing technologies often improve moisture permeability by introducing polar hydrophilic components into polyurethane. For example, patent application CN109096677A discloses a method for preparing a polyurethane film with high water pressure resistance and high moisture permeability. This method involves adding methyl methacrylate, octafluoropentyl acrylate, and perfluoropolyether to a polyurethane solution to form a mixture, which is then extruded using a twin-screw air compressor and blown into a film using a blown film machine to prepare the finished product. The perfluoropolyether is used to increase hydrophilic groups and improve moisture permeability. However, this method is complex, and the various added components have conflicting effects on water pressure resistance and moisture permeability, resulting in unsatisfactory performance.

[0007] For example, patent application CN111171554A discloses an ultra-high moisture permeability matte thermoplastic polyurethane composition and its preparation method. This method obtains a high moisture permeability matte thermoplastic polyurethane elastomer by adding TPEE and zeolite powder. The polyether soft segments in TPEE can increase the hydrophilic groups in the system, and the porous channels of the porous zeolite can form channels inside the membrane to improve moisture permeability. However, there is a certain degree of incompatibility between TPEE and TPU when blended, affecting the product's processability and mechanical properties.

[0008] In summary, to broaden the application range of TPU in waterproof and breathable films, it is necessary to develop a thermoplastic polyurethane elastomer for breathable films and its preparation method, so as to prepare a thermoplastic polyurethane elastomer for breathable films that has both high melting point, high moisture permeability and easy processing. Summary of the Invention

[0009] The purpose of this invention is to solve the problems existing in the prior art and to provide a thermoplastic polyurethane elastomer for breathable membranes and its preparation method.

[0010] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0011] A thermoplastic polyurethane elastomer for a moisture-permeable membrane has the following general structural formula;

[0012]

[0013] Wherein, R1 represents the corresponding diisocyanate moiety, R2 represents the corresponding small molecule diol chain extender moiety, and R3 represents...

[0014] x=2~10, n=3~15, a=20~30;

[0015] A 15 μm thick film made from a thermoplastic polyurethane elastomer for moisture permeability has a moisture permeability >10000 g / m³. 2 day.

[0016] As a preferred technical solution:

[0017] As described above, a thermoplastic polyurethane elastomer for a breathable membrane, where R1 is... -CH2CH2CH2CH2CH2CH2-、

[0018] As described above, a thermoplastic polyurethane elastomer for a breathable membrane, where R2 is... -CH2CH2OCH2CH2- or

[0019] The thermoplastic polyurethane elastomer for a breathable membrane, as described above, has a melting point >200℃ and a melt strength MSI of 2.8 to 3.8.

[0020] The present invention also provides a method for preparing a thermoplastic polyurethane elastomer for a breathable membrane as described above, wherein a polyether macromolecular diol with a pyridine-type ionic liquid structure in its molecular structure, an organic diisocyanate, and a small molecule diol chain extender are subjected to a polymerization reaction to obtain a thermoplastic polyurethane elastomer for a breathable membrane.

[0021] As a preferred technical solution:

[0022] The method for preparing a thermoplastic polyurethane elastomer for a breathable membrane as described above uses a polyether macromolecular diol with a pyridine-type ionic liquid structure as shown below:

[0023]

[0024] Where a = 20 to 30.

[0025] In the method for preparing a thermoplastic polyurethane elastomer for a breathable membrane as described above, the organic diisocyanate is 2,6-toluene diisocyanate, 2,4-toluene diisocyanate, terephthalic diisocyanate, 1,6-hexane diisocyanate, diphenylmethane-4,4'-diisocyanate, isophorone diisocyanate, phenylenediamine diisocyanate, 3,3'-dimethyl-4,4'-biphenyl diisocyanate, cyclohexanedimethyl diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, naphthalene-1,5-diisocyanate, or 3,3'-dimethyl-4,4'-diphenylmethane diisocyanate.

[0026] In the preparation method of the thermoplastic polyurethane elastomer for a breathable membrane as described above, the small molecule diol chain extender is ethylene glycol, 1,4-butanediol, 1,6-hexanediol, propylene glycol, diethylene glycol, or hydroquinone dihydroxyethyl ether.

[0027] The method for preparing a thermoplastic polyurethane elastomer for a breathable membrane, as described above, uses the total mass of polyether macromolecular diols, organic diisocyanates, and small molecule diol chain extenders with pyridine-type ionic liquid structures in their molecular structure as a basis. The proportion of polyether macromolecular diols with pyridine-type ionic liquid structures in their molecular structure is 30-45%, the proportion of organic diisocyanates is 40-55%, and the proportion of small molecule diol chain extenders is 10-20%. When the proportion of polyether macromolecular diols is less than 30%, the soft segment content is too low and will affect the breathability. When the proportion of polyether macromolecular diols is higher than 45%, the soft segment content is high and will reduce the melting point of TPU.

[0028] The method for preparing a thermoplastic polyurethane elastomer for a breathable membrane as described above involves a twin-screw reactive extrusion method for polymerization, with a screw speed of 150–300 r / min and a polymerization temperature of 150–230 °C.

[0029] Invention principle:

[0030] Ionic liquids are compounds composed entirely of organic cations and organic / inorganic anions. The types of cations and anions that make up ionic liquids are diverse, and they can be classified into different types based on the cations they contain, such as imidazole, pyridine, quaternary ammonium, quaternary phosphine, and pyrrole. Currently, the addition of ionic liquids to polyurethanes is mainly through physical blending. The primary function of the ionic liquid in combining with polyurethane is to enhance the antistatic and flame-retardant properties of the polyurethane.

[0031] The TPU soft segment molecular chain structure of this invention is as follows: the main chain is a hydrophilic polyether segment (similar to polyethylene glycol PEG, rich in ether bonds), and the side chains are connected to a pyridine chloride ionic liquid via methylene (-CH2-) groups. The TPU of this invention significantly improves moisture permeability through the following mechanism:

[0032] (1) The hydrophilic polyether backbone forms hydrogen bonds with water molecules through ether bonds, and transports water molecules through the movement of the backbone segments, forming a basic water molecule transport network; while the side-chain pyridine chloride ionic liquid, through the rotation and wobbling of its respective methylene groups, brings its charged parts close to each other without significantly changing the conformation of the backbone, forming ion cluster channels in the TPU soft segment. These channels adsorb water molecules from the surrounding environment through ion-dipole interactions, and water molecules undergo rapid "adsorption-desorption-re-adsorption" jump diffusion in the ion cluster channels to form transport.

[0033] (2) Thermoplastic polyurethane elastomer (TPU) is prepared by reacting macromolecular diols, small-molecule diol chain extenders, and diisocyanates. In the TPU molecular chain, macromolecular diols exist in the soft segment region, while small-molecule diol chain extenders react with diisocyanates to form the hard segment region. The soft and hard segments, with similar polarities, have a certain degree of compatibility, resulting in incomplete phase separation. Part of the hard segment remains in the soft segment phase, thus affecting the diffusion rate of water molecules in TPU and leading to a decrease in moisture permeability. This invention introduces a pyridine ring ionic liquid structure with permanent dipoles and ionic charges onto the macromolecular diol molecular chain, transforming the polarity of the soft segment into ionic polarity with ion-dipole interaction. This creates a polarity mismatch between the soft and hard segments, promoting phase separation and facilitating the diffusion of water molecules in the soft segment phase.

[0034] (3) The rigid and large pyridine ring has a steric hindrance effect, which can reduce the stacking advantage of soft segment molecular chains, inhibit orientation crystallization during TPU processing, increase the dynamic free volume of the soft segment phase, and promote the diffusion of water molecules.

[0035] However, replacing the pyridine-type chloride ionic liquid used in this invention with other types of ionic liquids does not effectively improve moisture permeability. This is because the level of moisture permeability depends not only on the material's ability to adsorb water molecules, but also on the ease with which water molecules migrate / diffuse within the material. An efficient moisture permeability channel requires the material to have a moderate affinity for molecules, meaning it can adsorb them and easily release them, allowing them to continue diffusing forward.

[0036] (1) Comparison with imidazole ions;

[0037] Advantages of pyridine-based compounds: moderate affinity and high mobility.

[0038] The pyridine ring is an aromatic ring with its positive charge delocalized throughout. Its interaction with water molecules is primarily an ion-dipole interaction of moderate strength. The pyridine ring lacks protons (acidic hydrogen) to provide strong hydrogen bonds. This means that the binding force between water molecules and pyridine ions is sufficient to "capture" them into the channel, but not to "lock them in." Water molecules can undergo rapid, hopping diffusion through pyridine ion channels, characterized by low migration resistance and extremely high permeability.

[0039] The drawback of imidazoles: excessively strong hydrogen bonds cause water molecules to become trapped.

[0040] The π-system electron cloud characteristics of the imidazole ring determine that it is a stronger hydrogen bond acceptor than the pyridine ring, forming very strong hydrogen bonds with water molecules. While this strong interaction enhances the water absorption of the material, it significantly reduces the mobility of water molecules. Water molecules are excessively bound around the imidazole ions, making it difficult for them to desorb and diffuse to the next site.

[0041] (2) Comparison with quaternary ammonium and quaternary phosphine ions;

[0042] Advantages of pyridine-type: rigid planar structure and regular channels.

[0043] The pyridine ring is a rigid planar aromatic structure, which facilitates the formation of ordered, closely packed ion channels when aggregated, providing a smooth and continuous path for water molecules to pass through. Its relatively uniform charge distribution is conducive to the formation of a stable ion environment.

[0044] Defects of quaternary ammonium / quaternary phosphine: flexible structure and disordered clusters.

[0045] Quaternary ammonium and quaternary phosphine ions are typically flexible, non-planar spherical or conical structures. When they aggregate, they are difficult to form regular, continuous nanochannels and are more likely to form loose, disordered ion clusters. This disordered aggregation state leads to discontinuous and highly tortuous hydrophilic channels. Water molecules need to "wind around" between these chaotic clusters, resulting in long diffusion paths and high resistance, which severely limits the moisture permeability.

[0046] (3) Comparison with pyrrole ions;

[0047] Pyrrole-type ions: Pyrrole-type ions are unstable, anti-aromatic rings with their positive charge highly localized around the nitrogen atom. Water molecules are strongly bound around this localized charge center and cannot migrate rapidly. Furthermore, their non-planar and unstable structure essentially eliminates their ability to self-assemble into regular channels. Having lost its aromaticity, it can only form disordered ion aggregates, affecting moisture permeability.

[0048] Furthermore, the present invention introduces pyridine-type chloride ionic liquid into the TPU side chain, which can enhance the intermolecular forces through charge interaction, improve the melt strength of TPU during processing, and make it more suitable for blow molding.

[0049] Beneficial effects:

[0050] (1) The high-melting-point (melting point > 200℃) thermoplastic polyurethane elastomer prepared by the present invention, by introducing pyridine-type chloride ionic liquid into the TPU side chain, can enhance the intermolecular forces through charge interaction, thereby improving melt strength. The processing window can be increased to 15-20℃, making it suitable for blow molding. Furthermore, the film prepared with it has excellent moisture permeability, with a moisture permeability of >10000g / m for a 15μm thick film. 2 However, ordinary high-melting-point thermoplastic polyurethane elastomers, under the same conditions, have low melt strength and a narrow processing window (below 5°C), which makes blow molding die setting difficult. Films of the same thickness prepared using these elastomers have a moisture permeability of <8000g / m³.2 day.

[0051] (2) The preparation method of the present invention is simple, and the introduction of pyridine chloride ionic liquid into the TPU side chain is more conducive to promoting the microphase separation of TPU hard segment and soft segment, inhibiting soft segment crystallization, improving moisture permeability, and improving the melt strength of the material, thus overcoming the disadvantages of complex process and difficult operation of the existing technology. Attached Figure Description

[0052] Figure 1 The infrared spectrum of the thermoplastic polyurethane elastomer for the breathable membrane prepared in Example 1 of this invention;

[0053] Figure 2 The image shows the DSC curve of the thermoplastic polyurethane elastomer for the breathable membrane prepared in Example 1 of this invention. Detailed Implementation

[0054] The present invention will be further described below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0055] The general structural formulas of the thermoplastic polyurethane elastomers for the breathable membranes prepared in the following embodiments are as follows:

[0056]

[0057] Wherein, R1 represents the corresponding diisocyanate moiety, R2 represents the corresponding small molecule diol chain extender moiety, and R3 represents... a=20~30, x=1~10, n=3~15;

[0058] The general structural formulas of the polyether macromolecular diols with pyridine-type ionic liquid structures used in the following embodiments are as follows:

[0059]

[0060] To ensure that the performance of the substances used in each embodiment and comparative example is fully disclosed, the manufacturers and brands of the substances are specified. Other products from manufacturers and brands that conform to the limitations of this invention are also feasible.

[0061] The test methods for the relevant performance indicators in the following embodiments and comparative examples are as follows:

[0062] Melting point: The thermoplastic polyurethane elastomers used to prepare the breathable membranes in each embodiment and comparative example were used as samples, and the melting point of 6 mg of the samples was tested using a differential scanning calorimeter (DSC, model Q250, manufactured by TA Inc., USA).

[0063] Moisture permeability: The moisture permeable membranes prepared in each example and comparative example were used as samples made of thermoplastic polyurethane elastomer. The samples were blown into a film with a thickness of 15 μm using a blown film machine (SCM-45, Zhangjiagang Lianjiang Machinery Co., Ltd.). The moisture permeability of the film was tested according to the inverted cup method specified in ASTM E96 standard.

[0064] Temperature window for maintaining stable film thickness in blown film extrusion die: The breathable films prepared in each embodiment and comparative example using thermoplastic polyurethane elastomer were used as samples. The samples were then blown onto a blown film extrusion machine (SCM-45, Zhangjiagang Lianjiang Machinery Co., Ltd.) to produce films with a thickness of 15μm. Under the premise of maintaining a uniform and stable film thickness, the die temperature was adjusted, and the adjusted temperature range was recorded as the temperature window of the die zone of the blown film extrusion machine. The screw speed was 400rpm, and the temperatures of each zone of the extruder were 200℃, 230℃, 230℃, 220℃, 210℃, and 200℃ (die).

[0065] Melt strength MSI: The thermoplastic polyurethane elastomers used to prepare the breathable membranes in each example and comparative example were used as samples. The samples were then vertically extruded into two 100mm long tube blanks using a single-screw extruder (SJ-30, Wuxi Lanling Plastic Machinery Co., Ltd.). The time taken to extrude the two tube blanks was recorded as T1 and T2, respectively. The melt strength MSI (i.e., MSI = T1 / T2) was then calculated based on T1 and T2. The minimum MSI is 1. The smaller the MSI, the higher the melt strength. The screw speed was 400 rpm, and the temperatures of each zone of the extruder were 200℃, 230℃, 230℃, 220℃, 210℃, and 210℃ (die). The die diameter was 30mm and the thickness was 2mm.

[0066] Example 1

[0067] A method for preparing a thermoplastic polyurethane elastomer for a moisture-permeable membrane, comprising the following steps:

[0068] (1) Preparation of polyether macromolecular diols with pyridine-type ionic liquid structures in their molecular structures;

[0069] (1.1) At 23°C, 8 mL of 1,2-dichloroethane was added to a 500 mL three-necked flask, followed by 0.4 mL of 1,3-propanediol injected with a syringe and stirred until homogeneous. Then, dry nitrogen gas was introduced, followed by 0.5 mL of anhydrous SnCl4 injected with a syringe. Then, 130 mL of epichlorohydrin was added at 30°C. The solution gradually changed from a colorless liquid to a pale yellow viscous liquid. Finally, the water bath temperature was adjusted to 30°C and the reaction was carried out at a constant temperature for 10 h.

[0070] (1.2) Add 60 mL of 1,2-dichloroethane to the system after the reaction and stir until homogeneous. Then wash the mixture with a methanol solution of tetrasodium ethylenediaminetetraacetate, allow it to stand and separate into layers. Then wash the lower organic phase three times with a methanol aqueous solution at 60 °C. First, distill under reduced pressure for 4 h using a water pump, then treat it under reduced pressure to 0.67 Pa at 60 °C for 1 h using a vacuum pump to obtain hydroxyl-terminated polyepoxychloropropane ether. The mass fraction of the methanol solution of tetrasodium ethylenediaminetetraacetate is 10%, and the mass fraction of the methanol aqueous solution is 10%.

[0071] (1.3) 50 mL of toluene and 40 g of the hydroxyl-terminated polyepoxychloropropane ether prepared above were placed in a round-bottom flask and stirred for 8 min. 68 mL of pyridine was added to the system and stirred at 50 °C for 10 h. After cooling to 23 °C, 50 mL of diethyl ether was added. The reaction mixture was then transferred to a distillation flask and distilled under reduced pressure at 90 °C and 0.1 MPa to obtain a polyether macromolecular diol with pyridine-type ionic liquid in its molecular structure.

[0072] In the structural formula of the polyether macromolecular diol with a pyridine-type ionic liquid structure obtained, a is 20.

[0073] (2) The above-obtained polyether macromolecular diol with pyridine ionic liquid structure, diphenylmethane-4,4'-diisocyanate (MDI) and 1,4-butanediol (BDO) were polymerized by twin-screw reactive extrusion to prepare a thermoplastic polyurethane elastomer for breathable membranes; wherein, the screw speed was 200 r / min, the polymerization temperature was 220℃, and the polymerization time was 1 min; based on the total mass of polyether macromolecular diol with pyridine ionic liquid structure, organic diisocyanate and small molecule diol chain extender, the proportion of polyether macromolecular diol with pyridine ionic liquid structure was 37%, the proportion of organic diisocyanate was 50%, and the proportion of small molecule diol chain extender was 13%;

[0074] In the final structure of the thermoplastic polyurethane elastomer used for the breathable membrane, R1 is... R2 is x is 4, n is 3;

[0075] The DSC curve of thermoplastic polyurethane elastomer for breathable membranes is as follows: Figure 2 As shown in the figure, its melting point is 211℃; the melt strength (MSI) of the thermoplastic polyurethane elastomer used for the moisture-permeable membrane is 3.8.

[0076] Infrared spectra of thermoplastic polyurethane elastomers used in breathable membranes, such as Figure 1 As shown in the figure, 1104cm -1 The peak is located at 2937 cm⁻¹, representing the soft segment of the polyether in TPU. -1 and 2855cm -1 The position is the methylene peak in the polyether soft segment and chain extender butanediol, at 1533 cm⁻¹. -1 and 780cm -1 The location is the characteristic peak of hard segment MDI, 3322 cm⁻¹. -1 The position is the characteristic peak of urethane in polyurethane, 1686 cm⁻¹. -1 and 1259cm 1 The position is a characteristic peak of the pyridine ring, which indicates that this embodiment successfully synthesized a thermoplastic polyurethane elastomer with pyridine-type ionic liquid in its molecular structure.

[0077] A 15 μm thick film made from thermoplastic polyurethane elastomer for moisture permeability has a moisture permeability of 11021 g / m³. 2 The temperature window for setting the die of the blown film machine to maintain stable film thickness is 15℃.

[0078] Comparative Example 1

[0079] A thermoplastic polyurethane elastomer for a breathable membrane is basically the same as in Example 1, except that in step (1.3), pyridine is replaced with N-methylimidazole, and finally a polyether macromolecular diol with an imidazole-type ionic liquid in its molecular structure is obtained.

[0080] Accordingly, the polyether macromolecular diol with a pyridine-type ionic liquid structure in the molecular structure in step (2) is replaced with an equal mass of the polyether macromolecular diol with an imidazole-type ionic liquid structure prepared in this comparative example.

[0081] The final structure of the thermoplastic polyurethane elastomer used for the breathable membrane is as follows: In the formula, R1 is R2 is R3 is Where a is 20, x is 4, and n is 3;

[0082] A 15 μm thick film made from thermoplastic polyurethane elastomer for moisture permeability has a moisture permeability of 7128 g / m³. 2 day.

[0083] Comparing Comparative Example 1 and Example 1, it can be seen that the moisture permeability of the thermoplastic polyurethane elastomer used in the moisture permeable membrane prepared in this comparative example is greatly reduced. This is because, compared with the pyridine ring, the π-system electron cloud characteristics of the imidazole ring determine that it is a stronger hydrogen bond acceptor than the pyridine ring. It can form very strong hydrogen bonds with water molecules. Although this strong interaction enhances the water absorption of the material, it will significantly reduce the mobility of water molecules. Water molecules will be too strongly bound around the imidazole ions, making it difficult to desorb and diffuse to the next site, thus leading to a decrease in the moisture permeability of the membrane.

[0084] Comparative Example 2

[0085] A thermoplastic polyurethane elastomer for a breathable membrane is basically the same as in Example 1, except that in step (1.3), pyridine is replaced with triethylamine, and finally a polyether macromolecular diol with a quaternary ammonium ionic liquid in its molecular structure is obtained.

[0086] Accordingly, the polyether macromolecular diol with a pyridine-type ionic liquid structure in the molecular structure in step (2) is replaced with an equal mass of the polyether macromolecular diol with a quaternary ammonium-type ionic liquid structure prepared in this comparative example.

[0087] The final structure of the thermoplastic polyurethane elastomer used for the breathable membrane is as follows: In the formula, R1 is R2 is R3 is Where a is 20, x is 4, and n is 3;

[0088] A 15 μm thick film made from thermoplastic polyurethane elastomer for moisture permeability has a moisture permeability of 7789 g / m³. 2 day.

[0089] Comparative Example 3

[0090] A thermoplastic polyurethane elastomer for a breathable membrane is basically the same as in Example 1, except that in step (1.3), pyridine is replaced with tributylphosphine, and finally a polyether macromolecular diol with quaternary phosphine-type ionic liquid in its molecular structure is obtained.

[0091] Accordingly, the polyether macromolecular diol with a pyridine-type ionic liquid structure in the molecular structure in step (2) is replaced with an equal mass of the polyether macromolecular diol with a quaternary phosphine-type ionic liquid structure prepared in this comparative example.

[0092] The final structure of the thermoplastic polyurethane elastomer used for the breathable membrane is given by the formula, where R1 is... R2 is R3 is Where a is 20, x is 4, and n is 3;

[0093] A 15 μm thick film made from thermoplastic polyurethane elastomer for moisture permeability has a moisture permeability of 7697 g / m³. 2 day.

[0094] Comparing Comparative Examples 2, 3 and 1, it can be seen that the moisture permeability of the membranes prepared in Comparative Examples 2 and 3 using thermoplastic polyurethane elastomers is greatly reduced. This is because, compared with pyridine rings, quaternary ammonium ions and quaternary phosphine ion liquids are both flexible, non-planar spherical or conical structures. When they aggregate, they are difficult to form regular, continuous nanochannels and are more likely to form loose, disordered ion clusters. This disordered aggregation state leads to discontinuous hydrophilic channels with high tortuosity. Water molecules need to "wind around" between these disordered clusters, resulting in long diffusion paths and high resistance, which seriously limits the moisture permeability efficiency.

[0095] Comparative Example 4

[0096] A thermoplastic polyurethane elastomer for a breathable membrane is basically the same as in Example 1, except that in step (1.3), pyridine is replaced with pyrrolidine, and finally a polyether macromolecular diol with pyrrole-type ionic liquid in its molecular structure is obtained.

[0097] Accordingly, the polyether macromolecular diol with a pyridine-type ionic liquid structure in the molecular structure in step (2) is replaced with an equal mass of the polyether macromolecular diol with a pyrrole-type ionic liquid structure prepared in this comparative example.

[0098] The final structure of the thermoplastic polyurethane elastomer used for the breathable membrane is as follows: In the formula, R1 is R2 is R3 is Where a is 20, x is 4, and n is 3;

[0099] A 15 μm thick film made from thermoplastic polyurethane elastomer for moisture permeability has a moisture permeability of 7652 g / m³. 2 day.

[0100] Comparing Comparative Example 4 with Example 1, it can be seen that the moisture permeability of the thermoplastic polyurethane elastomer used in the moisture permeable membrane prepared in this comparative example is greatly reduced. This is because, compared with the pyridine ring, the pyrrole ion is an unstable, anti-aromatic ring. Its positive charge is highly localized around the nitrogen atom, and water molecules are strongly bound around the localized charge center and cannot migrate quickly. At the same time, its non-planar and unstable structure has basically lost the ability to self-assemble into regular channels. After losing its aromaticity, its non-planar and unstable structure has basically lost the ability to self-assemble into regular channels and can only form disordered ion aggregates, which affects the moisture permeability.

[0101] Example 2

[0102] A method for preparing a thermoplastic polyurethane elastomer for a moisture-permeable membrane, comprising the following steps:

[0103] (1) Preparation of polyether macromolecular diols with pyridine-type ionic liquid structures in their molecular structures;

[0104] (1.1) At 23°C, 8 mL of 1,2-dichloroethane was added to a 500 mL three-necked flask, followed by 0.4 mL of 1,3-propanediol injected with a syringe and stirred until homogeneous. Then, dry nitrogen gas was introduced, followed by 0.5 mL of anhydrous SnCl4 injected with a syringe. Then, 130 mL of epichlorohydrin was added at 30°C. The solution gradually changed from a colorless liquid to a pale yellow viscous liquid. Finally, the water bath temperature was adjusted to 30°C and the reaction was carried out at a constant temperature for 11.5 h.

[0105] (1.2) Add 60 mL of 1,2-dichloroethane to the system after the reaction and stir until homogeneous. Then wash the mixture with a methanol solution of tetrasodium ethylenediaminetetraacetate, allow it to stand and separate into layers. Then wash the lower organic phase three times with a methanol aqueous solution at 60 °C. First, distill under reduced pressure for 4 h using a water pump, then treat it under reduced pressure to 0.67 Pa at 60 °C for 1 h using a vacuum pump to obtain hydroxyl-terminated polyepoxychloropropane ether. The mass fraction of the methanol solution of tetrasodium ethylenediaminetetraacetate is 10%, and the mass fraction of the methanol aqueous solution is 10%.

[0106] (1.3) 50 mL of toluene and 40 g of the hydroxyl-terminated polyepoxychloropropane ether prepared above were placed in a round-bottom flask and stirred for 8 min. 68 mL of pyridine was added to the system and stirred at 50 °C for 10 h. After cooling to 23 °C, 50 mL of diethyl ether was added. The reaction mixture was then transferred to a distillation flask and distilled under reduced pressure at 90 °C and 0.1 MPa to obtain a polyether macromolecular diol with pyridine-type ionic liquid in its molecular structure.

[0107] In the structural formula of the polyether macromolecular diol with a pyridine-type ionic liquid structure obtained, a is 22;

[0108] (2) The above-obtained polyether macromolecular diol with pyridine ionic liquid structure, diphenylmethane-4,4'-diisocyanate (MDI) and 1,4-butanediol (BDO) were polymerized by twin-screw reactive extrusion to prepare a thermoplastic polyurethane elastomer for breathable membranes; wherein, the screw speed was 200 r / min, the polymerization temperature was 210℃, and the polymerization time was 1.5 min; based on the total mass of polyether macromolecular diol with pyridine ionic liquid structure, organic diisocyanate and small molecule diol chain extender, the proportion of polyether macromolecular diol with pyridine ionic liquid structure was 40%, the proportion of organic diisocyanate was 45%, and the proportion of small molecule diol chain extender was 15%;

[0109] In the final structure of the thermoplastic polyurethane elastomer used for the breathable membrane, R1 is... R2 is x is 3, n is 3;

[0110] The thermoplastic polyurethane elastomer used for the breathable membrane has a melting point of 210℃ and a melt strength MSI of 3.3.

[0111] A 15 μm thick film made from thermoplastic polyurethane elastomer for moisture permeability has a moisture permeability of 11550 g / m³. 2 The temperature window for setting the die of the blown film machine to maintain stable film thickness is 17℃.

[0112] Comparative Example 5

[0113] A thermoplastic polyurethane elastomer for a breathable membrane is basically the same as in Example 2, except that step (1) is omitted, and the polyether macromolecular diol with a pyridine-type ionic liquid structure in the molecular structure of step (2) is replaced with an equal mass of PEG2000.

[0114] The final structure of the thermoplastic polyurethane elastomer used for the breathable membrane is as follows: In the formula, R1 is R2 is R3 is Where a is 44, x is 4, and n is 3;

[0115] The melt strength (MSI) of the thermoplastic polyurethane elastomer used for the breathable membrane is 7.3;

[0116] A 15 μm thick film made from thermoplastic polyurethane elastomer for moisture permeability has a moisture permeability of 5008 g / m³. 2 The temperature window for setting the die of the blown film machine to maintain stable film thickness is 3℃.

[0117] Comparing Comparative Example 5 and Example 2, it can be seen that the MSI value of the thermoplastic polyurethane elastomer used in the moisture-permeable membrane prepared in this comparative example increases, the melt strength decreases, and the moisture permeability of the film made from it decreases. This is because although using high molecular weight (number average molecular weight ≥ 2000 Daltons) macromolecular diols as soft segments to synthesize TPU can achieve a higher melting point, the long molecular chain characteristics of high molecular weight diols make them prone to orientation crystallization during blow molding and extrusion, which restricts the movement of soft segment molecular chains and cannot effectively improve moisture permeability. In addition, the intermolecular forces during processing are weaker than those of ionic liquids, which easily lead to slippage, resulting in a decrease in melt strength and a narrow processing temperature window.

[0118] Example 3

[0119] A method for preparing a thermoplastic polyurethane elastomer for a moisture-permeable membrane, comprising the following steps:

[0120] (1) Preparation of polyether macromolecular diols with pyridine-type ionic liquid structures in their molecular structures;

[0121] (1.1) At 23°C, 8 mL of 1,2-dichloroethane was added to a 500 mL three-necked flask, followed by 0.4 mL of 1,3-propanediol injected with a syringe and stirred until homogeneous. Then, dry nitrogen gas was introduced, followed by 0.5 mL of anhydrous SnCl4 injected with a syringe. Then, 130 mL of epichlorohydrin was added at 30°C. The solution gradually changed from a colorless liquid to a pale yellow viscous liquid. Finally, the water bath temperature was adjusted to 30°C and the reaction was carried out at a constant temperature for 16 h.

[0122] (1.2) Add 60 mL of 1,2-dichloroethane to the system after the reaction and stir until homogeneous. Then wash the mixture with a methanol solution of tetrasodium ethylenediaminetetraacetate, allow it to stand and separate into layers. Then wash the lower organic phase three times with a methanol aqueous solution at 60 °C. First, distill under reduced pressure for 4 h using a water pump, then treat it under reduced pressure to 0.67 Pa at 60 °C for 1 h using a vacuum pump to obtain hydroxyl-terminated polyepoxychloropropane ether. The mass fraction of the methanol solution of tetrasodium ethylenediaminetetraacetate is 10%, and the mass fraction of the methanol aqueous solution is 10%.

[0123] (1.3) 50 mL of toluene and 40 g of the hydroxyl-terminated polyepoxychloropropane ether prepared above were placed in a round-bottom flask and stirred for 8 min. 68 mL of pyridine was added to the system and stirred at 50 °C for 10 h. After cooling to 23 °C, 50 mL of diethyl ether was added. The reaction mixture was then transferred to a distillation flask and distilled under reduced pressure at 90 °C and 0.1 MPa to obtain a polyether macromolecular diol with pyridine-type ionic liquid in its molecular structure.

[0124] In the structural formula of the polyether macromolecular diol with a pyridine-type ionic liquid structure obtained, a is 27.

[0125] (2) The above-obtained polyether macromolecular diol with pyridine ionic liquid structure, diphenylmethane-4,4'-diisocyanate (MDI) and 1,4-butanediol (BDO) were polymerized by twin-screw reactive extrusion to prepare a thermoplastic polyurethane elastomer for breathable membranes; wherein, the screw speed was 200 r / min, the polymerization temperature was 190℃, and the polymerization time was 2 min; based on the total mass of polyether macromolecular diol with pyridine ionic liquid structure, organic diisocyanate and small molecule diol chain extender, the proportion of polyether macromolecular diol with pyridine ionic liquid structure was 42%, the proportion of organic diisocyanate was 40%, and the proportion of small molecule diol chain extender was 18%;

[0126] In the final structure of the thermoplastic polyurethane elastomer used for the breathable membrane, R1 is... R2 is x is 2, n is 4;

[0127] The thermoplastic polyurethane elastomer used for the breathable membrane has a melting point of 207℃ and a melt strength MSI of 2.9.

[0128] A 15 μm thick film made from thermoplastic polyurethane elastomer for moisture permeability has a moisture permeability of 12621 g / m³. 2 The temperature window for setting the die of the blown film machine to maintain stable film thickness is 18℃.

[0129] Comparative Example 6

[0130] A thermoplastic polyurethane elastomer for a breathable membrane is basically the same as in Example 3, except that step (1) is omitted, and the polyether macromolecular diol with a pyridine-type ionic liquid structure in the molecular structure of step (2) is replaced with an equal mass of PEG3000.

[0131] The final structure of the thermoplastic polyurethane elastomer used for the breathable membrane is as follows: In the formula, R1 is R2 is R3 is Where a is 67, x is 2, and n is 4;

[0132] The melt strength (MSI) of the thermoplastic polyurethane elastomer used for the breathable membrane is 8.2;

[0133] A 15 μm thick film made from thermoplastic polyurethane elastomer for moisture permeability has a moisture permeability of 7056 g / m³. 2 The die-setting temperature window for blown film machines that maintains stable film thickness is 4℃.

[0134] Comparing Comparative Example 6 and Example 3, it can be seen that the MSI value of the thermoplastic polyurethane elastomer used in the moisture-permeable membrane prepared in this comparative example increases, the melt strength decreases, and the moisture permeability of the film made from it decreases. This is because although using high molecular weight (number average molecular weight ≥ 2000 Daltons) macromolecular diols as soft segments to synthesize TPU can achieve a higher melting point, the long molecular chain characteristics of high molecular weight diols make them prone to orientation crystallization during blow molding and extrusion, which restricts the movement of soft segment molecular chains and cannot effectively improve moisture permeability. In addition, the intermolecular forces during processing are weaker than those of ionic liquids, which easily lead to slippage, resulting in a decrease in melt strength and a narrow processing temperature window.

[0135] Example 4

[0136] A method for preparing a thermoplastic polyurethane elastomer for a moisture-permeable membrane, comprising the following steps:

[0137] (1) Preparation of polyether macromolecular diols with pyridine-type ionic liquid structures in their molecular structures;

[0138] (1.1) At 23°C, 8 mL of 1,2-dichloroethane was added to a 500 mL three-necked flask, followed by 0.4 mL of 1,3-propanediol injected with a syringe and stirred until homogeneous. Then, dry nitrogen gas was introduced, followed by 0.5 mL of anhydrous SnCl4 injected with a syringe. Then, 130 mL of epichlorohydrin was added at 30°C. The solution gradually changed from a colorless liquid to a pale yellow viscous liquid. Finally, the water bath temperature was adjusted to 30°C and the reaction was carried out at a constant temperature for 15.5 h.

[0139] (1.2) Add 60 mL of 1,2-dichloroethane to the system after the reaction and stir until homogeneous. Then wash the mixture with a methanol solution of tetrasodium ethylenediaminetetraacetate, allow it to stand and separate into layers. Then wash the lower organic phase three times with a methanol aqueous solution at 60 °C. First, distill under reduced pressure for 4 h using a water pump, then treat it under reduced pressure to 0.67 Pa at 60 °C for 1 h using a vacuum pump to obtain hydroxyl-terminated polyepoxychloropropane ether. The mass fraction of the methanol solution of tetrasodium ethylenediaminetetraacetate is 10%, and the mass fraction of the methanol aqueous solution is 10%.

[0140] (1.3) 50 mL of toluene and 40 g of the hydroxyl-terminated polyepoxychloropropane ether prepared above were placed in a round-bottom flask and stirred for 8 min. 68 mL of pyridine was added to the system and stirred at 50 °C for 10 h. After cooling to 23 °C, 50 mL of diethyl ether was added. The reaction mixture was then transferred to a distillation flask and distilled under reduced pressure at 90 °C and 0.1 MPa to obtain a polyether macromolecular diol with pyridine-type ionic liquid in its molecular structure.

[0141] In the structural formula of the polyether macromolecular diol with a pyridine-type ionic liquid structure obtained, a is 26.

[0142] (2) The above-obtained polyether macromolecular diol with pyridine-type ionic liquid structure, 1,6-hexanediisocyanate and 1,6-hexanediol were polymerized by twin-screw reactive extrusion to prepare a thermoplastic polyurethane elastomer for breathable membranes; wherein, the screw speed was 150 r / min, the polymerization temperature was 150℃ and the polymerization time was 5 min; based on the total mass of polyether macromolecular diol with pyridine-type ionic liquid structure, organic diisocyanate and small molecule diol chain extender, the proportion of polyether macromolecular diol with pyridine-type ionic liquid structure was 30%, the proportion of organic diisocyanate was 55% and the proportion of small molecule diol chain extender was 15%;

[0143] In the final structure of the thermoplastic polyurethane elastomer used for the breathable membrane, R1 is -CH2CH2CH2CH2CH2CH2-, and R2 is... x is 10, n is 8;

[0144] The thermoplastic polyurethane elastomer used for the breathable membrane has a melting point of 202℃ and a melt strength MSI of 3.

[0145] A 15 μm thick film made from thermoplastic polyurethane elastomer for moisture permeability has a moisture permeability of 13228 g / m³. 2 The temperature window for setting the die of the blown film machine to maintain stable film thickness is 19℃.

[0146] Example 5

[0147] A method for preparing a thermoplastic polyurethane elastomer for a moisture-permeable membrane, comprising the following steps:

[0148] (1) Preparation of polyether macromolecular diols with pyridine-type ionic liquid structures in their molecular structures;

[0149] (1.1) At 23°C, 8 mL of 1,2-dichloroethane was added to a 500 mL three-necked flask, followed by 0.4 mL of 1,3-propanediol injected with a syringe and stirred until homogeneous. Then, dry nitrogen gas was introduced, followed by 0.5 mL of anhydrous SnCl4 injected with a syringe. Then, 130 mL of epichlorohydrin was added at 30°C. The solution gradually changed from a colorless liquid to a pale yellow viscous liquid. Finally, the water bath temperature was adjusted to 30°C and the reaction was carried out at a constant temperature for 15 h.

[0150] (1.2) Add 60 mL of 1,2-dichloroethane to the system after the reaction and stir until homogeneous. Then wash the mixture with a methanol solution of tetrasodium ethylenediaminetetraacetate, allow it to stand and separate into layers. Then wash the lower organic phase three times with a methanol aqueous solution at 60 °C. First, distill under reduced pressure for 4 h using a water pump, then treat it under reduced pressure to 0.67 Pa at 60 °C for 1 h using a vacuum pump to obtain hydroxyl-terminated polyepoxychloropropane ether. The mass fraction of the methanol solution of tetrasodium ethylenediaminetetraacetate is 10%, and the mass fraction of the methanol aqueous solution is 10%.

[0151] (1.3) 50 mL of toluene and 40 g of the hydroxyl-terminated polyepoxychloropropane ether prepared above were placed in a round-bottom flask and stirred for 8 min. 68 mL of pyridine was added to the system and stirred at 50 °C for 10 h. After cooling to 23 °C, 50 mL of diethyl ether was added. The reaction mixture was then transferred to a distillation flask and distilled under reduced pressure at 90 °C and 0.1 MPa to obtain a polyether macromolecular diol with pyridine-type ionic liquid in its molecular structure.

[0152] In the structural formula of the polyether macromolecular diol with a pyridine-type ionic liquid structure obtained, a is 25;

[0153] (2) The above-obtained polyether macromolecular diol with pyridine-type ionic liquid structure, terephthalic diisocyanate, and propylene glycol were polymerized by twin-screw reactive extrusion to prepare a thermoplastic polyurethane elastomer for breathable membranes; wherein, the screw speed was 300 r / min, the polymerization temperature was 230℃, and the polymerization time was 1.2 min; based on the total mass of the polyether macromolecular diol with pyridine-type ionic liquid structure, the organic diisocyanate, and the small molecule diol chain extender, the proportion of the polyether macromolecular diol with pyridine-type ionic liquid structure was 45%, the proportion of the organic diisocyanate was 45%, and the proportion of the small molecule diol chain extender was 10%;

[0154] In the final structure of the thermoplastic polyurethane elastomer used for the breathable membrane, R1 is... R2 is x is 6, n is 10;

[0155] The thermoplastic polyurethane elastomer used for the breathable membrane has a melting point of 208℃ and a melt strength MSI of 3.1.

[0156] A 15 μm thick film made from thermoplastic polyurethane elastomer for moisture permeability has a moisture permeability of 12312 g / m³. 2 The temperature window for setting the die of the blown film machine to maintain stable film thickness is 17℃.

[0157] Example 6

[0158] A method for preparing a thermoplastic polyurethane elastomer for a moisture-permeable membrane, comprising the following steps:

[0159] (1) Preparation of polyether macromolecular diols with pyridine-type ionic liquid structures in their molecular structures;

[0160] (1.1) At 23°C, 8 mL of 1,2-dichloroethane was added to a 500 mL three-necked flask, followed by 0.4 mL of 1,3-propanediol injected with a syringe and stirred until homogeneous. Then, dry nitrogen gas was introduced, followed by 0.5 mL of anhydrous SnCl4 injected with a syringe. Then, 130 mL of epichlorohydrin was added at 30°C. The solution gradually changed from a colorless liquid to a pale yellow viscous liquid. Finally, the water bath temperature was adjusted to 30°C and the reaction was carried out at a constant temperature for 14 h.

[0161] (1.2) Add 60 mL of 1,2-dichloroethane to the system after the reaction and stir until homogeneous. Then wash the mixture with a methanol solution of tetrasodium ethylenediaminetetraacetate, allow it to stand and separate into layers. Then wash the lower organic phase three times with a methanol aqueous solution at 60 °C. First, distill under reduced pressure for 4 h using a water pump, then treat it under reduced pressure to 0.67 Pa at 60 °C for 1 h using a vacuum pump to obtain hydroxyl-terminated polyepoxychloropropane ether. The mass fraction of the methanol solution of tetrasodium ethylenediaminetetraacetate is 10%, and the mass fraction of the methanol aqueous solution is 10%.

[0162] (1.3) 50 mL of toluene and 40 g of the hydroxyl-terminated polyepoxychloropropane ether prepared above were placed in a round-bottom flask and stirred for 8 min. 68 mL of pyridine was added to the system and stirred at 50 °C for 10 h. After cooling to 23 °C, 50 mL of diethyl ether was added. The reaction mixture was then transferred to a distillation flask and distilled under reduced pressure at 90 °C and 0.1 MPa to obtain a polyether macromolecular diol with pyridine-type ionic liquid in its molecular structure.

[0163] In the structural formula of the polyether macromolecular diol with a pyridine-type ionic liquid structure obtained, a is 24.

[0164] (2) The above-obtained polyether macromolecular diol with pyridine-type ionic liquid structure, 2,6-toluene diisocyanate and ethylene glycol were polymerized by twin-screw reactive extrusion to prepare a thermoplastic polyurethane elastomer for breathable membranes; wherein, the screw speed was 180 r / min, the polymerization temperature was 200℃, and the polymerization time was 2.5 min; based on the total mass of the polyether macromolecular diol with pyridine-type ionic liquid structure, the organic diisocyanate and the small molecule diol chain extender, the proportion of the polyether macromolecular diol with pyridine-type ionic liquid structure was 30%, the proportion of the organic diisocyanate was 50%, and the proportion of the small molecule diol chain extender was 20%;

[0165] In the final structure of the thermoplastic polyurethane elastomer used for the breathable membrane, R1 is... R2 is x is 5, n is 15;

[0166] The thermoplastic polyurethane elastomer used for the breathable membrane has a melting point of 209℃ and a melt strength MSI of 2.9.

[0167] A 15 μm thick film made from thermoplastic polyurethane elastomer for moisture permeability has a moisture permeability of 13121 g / m³. 2 The temperature window for setting the die of the blown film machine to maintain stable film thickness is 18℃.

[0168] Example 7

[0169] A method for preparing a thermoplastic polyurethane elastomer for a moisture-permeable membrane, comprising the following steps:

[0170] (1) Preparation of polyether macromolecular diols with pyridine-type ionic liquid structures in their molecular structures;

[0171] (1.1) At 23°C, 8 mL of 1,2-dichloroethane was added to a 500 mL three-necked flask, followed by 0.4 mL of 1,3-propanediol injected with a syringe and stirred until homogeneous. Then, dry nitrogen gas was introduced, followed by 0.5 mL of anhydrous SnCl4 injected with a syringe. Then, 130 mL of epichlorohydrin was added at 30°C. The solution gradually changed from a colorless liquid to a pale yellow viscous liquid. Finally, the water bath temperature was adjusted to 30°C and the reaction was carried out at a constant temperature for 10.5 h.

[0172] (1.2) Add 60 mL of 1,2-dichloroethane to the system after the reaction and stir until homogeneous. Then wash the mixture with a methanol solution of tetrasodium ethylenediaminetetraacetate, allow it to stand and separate into layers. Then wash the lower organic phase three times with a methanol aqueous solution at 60 °C. First, distill under reduced pressure for 4 h using a water pump, then treat it under reduced pressure to 0.67 Pa at 60 °C for 1 h using a vacuum pump to obtain hydroxyl-terminated polyepoxychloropropane ether. The mass fraction of the methanol solution of tetrasodium ethylenediaminetetraacetate is 10%, and the mass fraction of the methanol aqueous solution is 10%.

[0173] (1.3) 50 mL of toluene and 40 g of the hydroxyl-terminated polyepoxychloropropane ether prepared above were placed in a round-bottom flask and stirred for 8 min. 68 mL of pyridine was added to the system and stirred at 50 °C for 10 h. After cooling to 23 °C, 50 mL of diethyl ether was added. The reaction mixture was then transferred to a distillation flask and distilled under reduced pressure at 90 °C and 0.1 MPa to obtain a polyether macromolecular diol with pyridine-type ionic liquid in its molecular structure.

[0174] In the structural formula of the polyether macromolecular diol with a pyridine-type ionic liquid structure obtained, a is 21;

[0175] (2) The above-obtained polyether macromolecular diol with pyridine-type ionic liquid structure, cyclohexanedimethyl diisocyanate and diethylene glycol were polymerized by twin-screw reactive extrusion to prepare a thermoplastic polyurethane elastomer for breathable membranes; wherein, the screw speed was 210 r / min, the polymerization temperature was 210℃, and the polymerization time was 3 min; based on the total mass of polyether macromolecular diol with pyridine-type ionic liquid structure, organic diisocyanate and small molecule diol chain extender, the proportion of polyether macromolecular diol with pyridine-type ionic liquid structure was 44%, the proportion of organic diisocyanate was 41%, and the proportion of small molecule diol chain extender was 15%;

[0176] In the final structure of the thermoplastic polyurethane elastomer used for the breathable membrane, R1 is... R2 is -CH2CH2OCH2CH2-, x is 7, and n is 11;

[0177] The thermoplastic polyurethane elastomer used for the breathable membrane has a melting point of 215℃ and a melt strength MSI of 2.8.

[0178] A 15 μm thick film made from thermoplastic polyurethane elastomer for moisture permeability has a moisture permeability of 12176 g / m³. 2 The temperature window for setting the die of the blown film machine to maintain stable film thickness is 20℃.

[0179] Example 8

[0180] A method for preparing a thermoplastic polyurethane elastomer for a moisture-permeable membrane, comprising the following steps:

[0181] (1) Preparation of polyether macromolecular diols with pyridine-type ionic liquid structures in their molecular structures;

[0182] (1.1) At 23°C, 8 mL of 1,2-dichloroethane was added to a 500 mL three-necked flask, followed by 0.4 mL of 1,3-propanediol injected with a syringe and stirred until homogeneous. Then, dry nitrogen gas was introduced, followed by 0.5 mL of anhydrous SnCl4 injected with a syringe. After that, 130 mL of epichlorohydrin was added dropwise at 30°C. The solution gradually changed from a colorless liquid to a pale yellow viscous liquid. Finally, the water bath temperature was adjusted to 30°C and the reaction was carried out at a constant temperature for 11.5 h.

[0183] (1.2) Add 60 mL of 1,2-dichloroethane to the system after the reaction and stir until homogeneous. Then wash the mixture with a methanol solution of tetrasodium ethylenediaminetetraacetate, allow it to stand and separate into layers. Then wash the lower organic phase three times with a methanol aqueous solution at 60 °C. First, distill under reduced pressure for 4 h using a water pump, then treat it under reduced pressure to 0.67 Pa at 60 °C for 1 h using a vacuum pump to obtain hydroxyl-terminated polyepoxychloropropane ether. The mass fraction of the methanol solution of tetrasodium ethylenediaminetetraacetate is 10%, and the mass fraction of the methanol aqueous solution is 10%.

[0184] (1.3) 50 mL of toluene and 40 g of the hydroxyl-terminated polyepoxychloropropane ether prepared above were placed in a round-bottom flask and stirred for 8 min. 68 mL of pyridine was added to the system and stirred at 50 °C for 10 h. After cooling to 23 °C, 50 mL of diethyl ether was added. The reaction mixture was then transferred to a distillation flask and distilled under reduced pressure at 90 °C and 0.1 MPa to obtain a polyether macromolecular diol with pyridine-type ionic liquid in its molecular structure.

[0185] In the structural formula of the polyether macromolecular diol with a pyridine-type ionic liquid structure obtained, a is 22;

[0186] (2) The above-obtained polyether macromolecular diol with pyridine ionic liquid structure, isophorone diisocyanate and hydroquinone dihydroxyethyl ether were polymerized by twin-screw reactive extrusion to prepare a thermoplastic polyurethane elastomer for breathable membranes; wherein, the screw speed was 250 r / min, the polymerization temperature was 190℃, and the polymerization time was 3.5 min; based on the total mass of polyether macromolecular diol with pyridine ionic liquid structure, organic diisocyanate and small molecule diol chain extender, the proportion of polyether macromolecular diol with pyridine ionic liquid structure was 43%, the proportion of organic diisocyanate was 46%, and the proportion of small molecule diol chain extender was 11%;

[0187] In the final structure of the thermoplastic polyurethane elastomer used for the breathable membrane, R1 is... R2 is x is 3, n is 13;

[0188] The thermoplastic polyurethane elastomer used for the breathable membrane has a melting point of 211℃ and a melt strength MSI of 3.6.

[0189] A 15 μm thick film made from thermoplastic polyurethane elastomer for moisture permeability has a moisture permeability of 12089 g / m³. 2 The temperature window for setting the die of the blown film machine to maintain stable film thickness is 17℃.

[0190] Example 9

[0191] A method for preparing a thermoplastic polyurethane elastomer for a moisture-permeable membrane, comprising the following steps:

[0192] (1) Preparation of polyether macromolecular diols with pyridine-type ionic liquid structures in their molecular structures;

[0193] (1.1) At 23°C, 8 mL of 1,2-dichloroethane was added to a 500 mL three-necked flask, followed by 0.4 mL of 1,3-propanediol injected with a syringe and stirred until homogeneous. Then, dry nitrogen gas was introduced, followed by 0.5 mL of anhydrous SnCl4 injected with a syringe. Then, 130 mL of epichlorohydrin was added at 30°C. The solution gradually changed from a colorless liquid to a pale yellow viscous liquid. Finally, the water bath temperature was adjusted to 30°C and the reaction was carried out at a constant temperature for 20 h.

[0194] (1.2) Add 60 mL of 1,2-dichloroethane to the system after the reaction and stir until homogeneous. Then wash the mixture with a methanol solution of tetrasodium ethylenediaminetetraacetate, allow it to stand and separate into layers. Then wash the lower organic phase three times with a methanol aqueous solution at 60 °C. First, distill under reduced pressure for 4 h using a water pump, then treat it under reduced pressure to 0.67 Pa at 60 °C for 1 h using a vacuum pump to obtain hydroxyl-terminated polyepoxychloropropane ether. The mass fraction of the methanol solution of tetrasodium ethylenediaminetetraacetate is 10%, and the mass fraction of the methanol aqueous solution is 10%.

[0195] (1.3) 50 mL of toluene and 40 g of the hydroxyl-terminated polyepoxychloropropane ether prepared above were placed in a round-bottom flask and stirred for 8 min. 68 mL of pyridine was added to the system and stirred at 50 °C for 10 h. After cooling to 23 °C, 50 mL of diethyl ether was added. The reaction mixture was then transferred to a distillation flask and distilled under reduced pressure at 90 °C and 0.1 MPa to obtain a polyether macromolecular diol with pyridine-type ionic liquid in its molecular structure.

[0196] In the structural formula of the polyether macromolecular diol with a pyridine-type ionic liquid structure obtained, a is 30;

[0197] (2) The above-obtained polyether macromolecular diol with pyridine-type ionic liquid structure, dimethyl phthalate, and ethylene glycol were polymerized by twin-screw reactive extrusion to prepare a thermoplastic polyurethane elastomer for breathable membranes; wherein, the screw speed was 260 r / min, the polymerization temperature was 180℃, and the polymerization time was 2.3 min; based on the total mass of polyether macromolecular diol with pyridine-type ionic liquid structure, organic diisocyanate, and small molecule diol chain extender, the proportion of polyether macromolecular diol with pyridine-type ionic liquid structure was 38%, the proportion of organic diisocyanate was 45%, and the proportion of small molecule diol chain extender was 17%;

[0198] In the final structure of the thermoplastic polyurethane elastomer used for the breathable membrane, R1 is... R2 is x is 8, n is 7;

[0199] The thermoplastic polyurethane elastomer used for the breathable membrane has a melting point of 209℃ and a melt strength MSI of 3.2.

[0200] A 15 μm thick film made from thermoplastic polyurethane elastomer for moisture permeability has a moisture permeability of 11561 g / m³. 2 The temperature window for setting the die of the blown film machine to maintain stable film thickness is 19℃.

[0201] Example 10

[0202] A method for preparing a thermoplastic polyurethane elastomer for a moisture-permeable membrane, comprising the following steps:

[0203] (1) Preparation of polyether macromolecular diols with pyridine-type ionic liquid structures in their molecular structures;

[0204] (1.1) At 23°C, 8 mL of 1,2-dichloroethane was added to a 500 mL three-necked flask, followed by 0.4 mL of 1,3-propanediol injected with a syringe and stirred until homogeneous. Then, dry nitrogen gas was introduced, followed by 0.5 mL of anhydrous SnCl4 injected with a syringe. Then, 130 mL of epichlorohydrin was added at 30°C. The solution gradually changed from a colorless liquid to a pale yellow viscous liquid. Finally, the water bath temperature was adjusted to 30°C and the reaction was carried out at a constant temperature for 18 h.

[0205] (1.2) Add 60 mL of 1,2-dichloroethane to the system after the reaction and stir until homogeneous. Then wash the mixture with a methanol solution of tetrasodium ethylenediaminetetraacetate, allow it to stand and separate into layers. Then wash the lower organic phase three times with a methanol aqueous solution at 60 °C. First, distill under reduced pressure for 4 h using a water pump, then treat it under reduced pressure to 0.67 Pa at 60 °C for 1 h using a vacuum pump to obtain hydroxyl-terminated polyepoxychloropropane ether. The mass fraction of the methanol solution of tetrasodium ethylenediaminetetraacetate is 10%, and the mass fraction of the methanol aqueous solution is 10%.

[0206] (1.3) 50 mL of toluene and 40 g of the hydroxyl-terminated polyepoxychloropropane ether prepared above were placed in a round-bottom flask and stirred for 8 min. 68 mL of pyridine was added to the system and stirred at 50 °C for 10 h. After cooling to 23 °C, 50 mL of diethyl ether was added. The reaction mixture was then transferred to a distillation flask and distilled under reduced pressure at 90 °C and 0.1 MPa to obtain a polyether macromolecular diol with pyridine-type ionic liquid in its molecular structure.

[0207] In the structural formula of the polyether macromolecular diol with a pyridine-type ionic liquid structure obtained, a is 28;

[0208] (2) The above-obtained polyether macromolecular diol with pyridine ionic liquid structure, 3,3'-dimethyl-4,4'-biphenyl diisocyanate and hydroquinone dihydroxyethyl ether were polymerized by twin-screw reactive extrusion to prepare a thermoplastic polyurethane elastomer for breathable membranes; wherein, the screw speed was 280 r / min, the polymerization temperature was 170℃, and the polymerization time was 4.5 min; based on the total mass of the polyether macromolecular diol with pyridine ionic liquid structure, organic diisocyanate and small molecule diol chain extender, the proportion of the polyether macromolecular diol with pyridine ionic liquid structure was 41%, the proportion of organic diisocyanate was 47%, and the proportion of small molecule diol chain extender was 12%;

[0209] In the final structure of the thermoplastic polyurethane elastomer used for the breathable membrane, R1 is... R2 is x is 9, n is 11;

[0210] The thermoplastic polyurethane elastomer used for the breathable membrane has a melting point of 217℃ and a melt strength MSI of 3.6.

[0211] A 15 μm thick film made from thermoplastic polyurethane elastomer for moisture permeability has a moisture permeability of 11745 g / m³. 2 The temperature window for setting the die of the blown film machine to maintain stable film thickness is 17℃.

Claims

1. A thermoplastic polyurethane elastomer for a breathable membrane, characterized in that: It has the following general structural formula; ； Wherein, R1 represents the corresponding diisocyanate moiety, R2 represents the corresponding small molecule diol chain extender moiety, and R3 represents... ; x = 2~10, n = 3~15, a = 20~30; A 15 μm thick film made from a thermoplastic polyurethane elastomer for moisture permeability has a moisture permeability >10000 g / m³. 2 day.

2. The thermoplastic polyurethane elastomer for a breathable membrane according to claim 1, characterized in that, R1 is , , , , , , , , , , or .

3. The thermoplastic polyurethane elastomer for a breathable membrane according to claim 2, characterized in that, R2 is , , , , or .

4. The thermoplastic polyurethane elastomer for a breathable membrane according to claim 3, characterized in that, The thermoplastic polyurethane elastomer used for the breathable membrane has a melting point >200℃ and a melt strength MSI of 2.8~3.

8.

5. A method for preparing a thermoplastic polyurethane elastomer for a breathable membrane as described in any one of claims 1 to 4, characterized in that: A thermoplastic polyurethane elastomer for breathable membranes is prepared by polymerizing polyether macromolecular diols with pyridine-type ionic liquid structures, organic diisocyanates, and small molecule diol chain extenders.

6. The method for preparing a thermoplastic polyurethane elastomer for a breathable membrane according to claim 5, characterized in that, The general structural formula of polyether macromolecular diols with pyridine-type ionic liquid structures in their molecular structure is as follows: ； Where a = 20~30.

7. The method for preparing a thermoplastic polyurethane elastomer for a breathable membrane according to claim 5, characterized in that, The organic diisocyanate is 2,6-toluene diisocyanate, 2,4-toluene diisocyanate, terephthalic diisocyanate, 1,6-hexane diisocyanate, diphenylmethane-4,4'-diisocyanate, isophorone diisocyanate, phenylmethylene diisocyanate, 3,3'-dimethyl-4,4'-biphenyl diisocyanate, 1,4-cyclohexanedimethyl diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, naphthalene-1,5-diisocyanate, or 3,3'-dimethyl-4,4'-diphenylmethane diisocyanate.

8. The method for preparing a thermoplastic polyurethane elastomer for a breathable membrane according to claim 5, characterized in that, Small molecule diol chain extenders include ethylene glycol, 1,4-butanediol, 1,6-hexanediol, propylene glycol, diethylene glycol, or hydroquinone dihydroxyethyl ether.

9. The method for preparing a thermoplastic polyurethane elastomer for a breathable membrane according to claim 5, characterized in that, Based on the total mass of polyether macromolecular diols, organic diisocyanates, and small molecule diol chain extenders with pyridine-type ionic liquid structures in their molecular structures, the proportion of polyether macromolecular diols with pyridine-type ionic liquid structures in their molecular structures is 30-45%, the proportion of organic diisocyanates is 40-55%, and the proportion of small molecule diol chain extenders is 10-20%.

10. The method for preparing a thermoplastic polyurethane elastomer for a breathable membrane according to claim 5, characterized in that, The polymerization reaction is carried out using a twin-screw reactive extrusion method with a screw speed of 150~300 r / min and a polymerization temperature of 150~230℃.

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