A hyperbranched TPU nanofiber waterproof and breathable membrane and its preparation and application

Abstract

The invention provides a hyperbranched TPU nanofiber waterproof and breathable membrane and its preparation and application. The raw materials for preparing the hyperbranched TPU nanofiber waterproof and breathable membrane mainly include fluorinated hydroxy amino silane and diisocyanate, wherein the fluorinated hydroxy amino silane is prepared by hydrolysis and condensation of halogenated unsaturated silane and perfluoropolyether alcohol, and then addition with diethanolamine. A hyperbranched polyol is prepared by initiating the addition of amino groups in amino alcohol with unsaturated fluorinated silane, and the obtained hyperbranched polyol is reacted with diisocyanate to obtain a hyperbranched TPU polymer. The nanofiber membrane prepared by melt spinning of the polymer has a large number of nano-microporous structures, and the pores are densely connected due to the presence of perfluoropolyether, and has excellent waterproof and breathable properties and good resilience.

Description

Technical Field

[0001] The invention relates to the technical field of TPU fiber membranes, and in particular to a hyperbranched TPU nanofiber waterproof and breathable membrane and a preparation method and application thereof. Background Art

[0002] Nowadays, air conditioners have entered thousands of households and become a necessity in our lives. However, due to the use of air conditioners, the space is closed, causing "air conditioning disease", and the indoor air quality has attracted more and more attention. On the other hand, according to survey statistics, industry, construction, and transportation are the three main parts of energy consumption. The energy directly consumed by buildings during construction and use is close to 1 / 3 of the total social energy consumption, and heating and air conditioning energy consumption accounts for about 65%. In order to solve these problems, more and more people are committed to the innovation of traditional air conditioners: to ensure the circulation of indoor and outdoor air while reducing energy consumption as much as possible.

[0003] At present, the total heat exchanger is the best way to solve the above problems. As an air conditioning auxiliary device, it allows indoor and outdoor air to flow mutually, and through its core component, the total heat exchange membrane, it exchanges the energy of fresh air and exhaust air. This not only circulates the air, but also reduces the energy consumption of air conditioning. At present, the total heat exchanger has entered the industrial production stage, but many products use paper membrane as the total heat exchange membrane. However, with the popularity of total heat exchangers, commonly used heat exchange membrane cores include paper, aluminum foil, polyvinyl alcohol, chitosan, etc. As the use time increases, the shortcomings of these membranes are gradually exposed. For example, paper membranes will deform, deteriorate, mold, and breed bacteria after being damp in a humid environment, and they cannot be cleaned and have a short lifespan; aluminum foil cannot exchange humidity, which reduces the heat exchange efficiency; polymer membranes cannot exchange humidity, which reduces the heat exchange efficiency, and the water vapor permeability is low, which is difficult to prepare industrially. In view of this, new full heat exchange membranes have become a research hotspot. The research mainly focuses on the preparation of various full heat exchange membranes with excellent moisture permeability, high gas barrier properties, mildew resistance and flame retardancy through the compounding of different membrane materials and additives, so as to replace paper membranes, more effectively reduce air conditioning energy consumption and improve indoor air quality.

[0004] Among many polymer film materials, TPU film is a high-performance, environmentally friendly film material with TPU polymer as the main raw material. It can be divided into two types: polyester film and polyether film in terms of chemical composition; it can be divided into melt processing and solution processing in terms of preparation method. TPU film has excellent properties such as high strength, good toughness, wear resistance, cold resistance, oil resistance, and biodegradability. It can be used alone or in combination with other materials. In recent years, TPU film products have been widely used in the fields of footwear, waterproof and breathable fabrics, high-end handbags and leather goods, inflatable bladders, etc. However, ordinary TPU films still have problems such as poor moisture permeability, poor durability, and low utilization rate. Therefore, it is key to improve the structure of TPU and make it have more hydrophilic groups to improve the hydrophilic properties of TPU. Summary of the invention

[0005] In order to solve the above problems in the prior art, the present invention provides a hyperbranched TPU nanofiber waterproof breathable membrane and its preparation and application.

[0006] A hyperbranched TPU nanofiber waterproof breathable membrane is obtained by polymerizing and spinning diisocyanate and fluorinated hydroxyl aminosilane under the action of a catalyst, wherein the fluorinated hydroxyl aminosilane is prepared from terminal hydroxyl perfluoropolyether alcohol, diethanolamine and unsaturated halogenated silane.

[0007] In some embodiments of the present invention, the diisocyanate is at least one of isophorone diisocyanate, dicyclohexylmethane diisocyanate, toluene diisocyanate, 4,4′-diphenylmethane diisocyanate, 1,5-naphthalene diisocyanate and hexamethylene diisocyanate.

[0008] In some embodiments of the present invention, the preparation method of the fluorinated hydroxyaminosilane comprises the following steps:

[0009] S1: Add unsaturated halogenated silane to a reaction vessel, add terminal hydroxyl perfluoropolyether alcohol dropwise under stirring in an oil bath at 50-70°C for 2-3h, raise the temperature of the reaction system to 70-80°C for condensation reflux reaction, the condensation temperature is -10-0°C, until the pH of the system is 4.5-6.5, then stop heating;

[0010] S2: Add diethanolamine and organic solvent 1 to the reaction system obtained in S1 to carry out addition reaction, and then carry out distillation separation and purification. First, use atmospheric distillation to collect the unreacted terminal hydroxyl perfluoropolyether alcohol and transition fraction, and then use vacuum distillation to collect the target product to obtain the fluorinated hydroxyl aminosilane.

[0011] In some embodiments of the present invention, in S1, the structure of the unsaturated halogenated silane is R-SiX3, wherein R1 is a C2-5 unsaturated olefin group, and X is F, Cl, Br, or I.

[0012] In some embodiments of the present invention, in S1, the structure of the hydroxy-terminated perfluoropolyether alcohol is as shown in Formula I: ;

[0013] In formula I, n=4-7, m=6-11; the number average molecular weight of the terminal hydroxyl perfluoropolyether alcohol is 1000-1500, and the specific medicine can be purchased from Solvay, Italy.

[0014] In some embodiments of the present invention, the dosage of the unsaturated halogenated silane and the terminal hydroxyl perfluoropolyether alcohol satisfies the molar ratio of -X:-OH of 1:1-1.5; the dosage of the unsaturated halogenated silane and diethanolamine satisfies the molar ratio of -C=C-:-NH of 0.8-1:1.

[0015] In the present invention, unsaturated halogenated silane is reacted with terminal hydroxyl fluorinated polyether alcohol to undergo alcoholysis to prepare fluorinated unsaturated polyether silane, and the reaction principle is shown in Formula II: ;

[0016] The secondary amine group in the diethanolamine is then used to react with the double bonds in the above-mentioned fluorine-containing unsaturated polyether silane to produce an addition reaction to obtain a hyperbranched diol. In the above-mentioned reaction process, the inventors found that the molar amount of halogen atoms contained in the unsaturated halogenated silane in the system should not differ too much from the molar amount of hydroxyl groups contained in the terminal hydroxyl perfluoropolyether alcohol. If there are too many halogen atoms, it will affect the existence state of hydroxyl groups in the subsequent diethanolamine, thereby affecting the performance of the hyperbranched TPU fiber nanofilm. After multiple tests, it was confirmed that the molar ratio of the unsaturated halogenated silane to the terminal hydroxyl perfluoropolyether alcohol must satisfy the molar ratio of -X:-OH of 1:1-1.5. The reaction of diethanolamine with the unsaturated halogenated silane should try to ensure that the unsaturated halogenated silane reacts completely to obtain the maximum degree of hyperbranched TPU polymer.

[0017] In some embodiments of the present invention, the organic solvent 1 in S2 is at least one of chloroform, dichloromethane, ether, toluene, methanol, ethanol, and isopropanol.

[0018] In some embodiments of the present invention, the atmospheric distillation in S2 collects a fraction at 75-80°C, and the reduced pressure distillation collects a fraction at 75-95°C.

[0019] A preparation method of the hyperbranched TPU nanofiber waterproof and breathable membrane comprises the following steps: vacuum dehydrating the diisocyanate and fluorinated hydroxyl aminosilane, adding them into a reactor filled with inert gas in a molar ratio of -N=C=O:-OH=2:0.5-1, adding an organic solvent 2 to dissolve, adding a catalyst accounting for 0.05-0.08wt% of the total reaction system mass, stirring and reacting at 40-65°C for 2-3h, removing the organic solvent 2 by reduced pressure distillation, and spinning them into a membrane on a receiving matrix by electrostatic spinning to obtain the hyperbranched TPU nanofiber waterproof and breathable membrane.

[0020] In some embodiments of the present invention, the organic solvent 2 is at least one of an alcohol solvent, an ether solvent, a ketone solvent, tetrahydrofuran (THF), and N,N-dimethylformamide (DMF).

[0021] In some embodiments of the present invention, the catalyst is at least one of a tertiary amine catalyst and an organotin catalyst. Specifically, the tertiary amine catalyst can be selected from triethylenediamine, triethylamine, trimethylbenzylamine, dimethylethanolamine, etc., and the organotin catalyst can be selected from stannous octoate, dibutyltin dilaurate, etc.

[0022] In some embodiments of the present invention, the conditions for electrospinning the hyperbranched TPU polymer are as follows: the receiving substrate is non-woven fabric, glossy paper, aluminum foil, metal mesh, etc., the infusion rate is 1-5 ml / h, the spinning voltage is 25-50 kV, the spinning speed is 50-100 r / min, the spinning temperature is 15-30°C, and the relative humidity is 30-90%.

[0023] In some embodiments of the present invention, during the preparation process of the hyperbranched TPU polymer, additives that meet the requirements, such as thermally conductive nanoparticles, bactericides, etc., may be added.

[0024] The above-mentioned hyperbranched TPU nanofiber waterproof and breathable membrane is used as a total heat exchange membrane in the field of total heat exchangers.

[0025] Beneficial effects: Compared with the prior art, the present invention introduces fluorine-containing unsaturated polyether silane prepared by alcoholysis of perfluoropolyether alcohol and unsaturated halogenated silane into TPU polymer to form a hyperbranched structure with the main chain of TPU, wherein a large number of fluorine-containing polyether segments are contained, which greatly increases the waterproofness of the hyperbranched TPU polymer; in the process of spinning and forming, the presence of fluorine and the hyperbranched structure make the final nanofiber membrane have a large number of nanoscale pores, and at the same time, the hydrogen bonding between ether bonds and between ether bonds and amide groups forms a dense connection between the pores, which can not only improve the moisture permeability of the membrane, but also utilize the compatibility of ether bonds with metal materials to increase the thermal conductivity of the membrane. In addition, the formation of the hyperbranched structure also gives the hyperbranched TPU nanofiber waterproof and breathable membrane a resilience, making it not easy to deform during practical applications, and increasing its service life. DETAILED DESCRIPTION

[0026] The present invention is described in further detail below in conjunction with examples. It should be noted that the following embodiments and comparative examples are examples of the present invention and are only used to illustrate the present invention, but not to limit the present invention. Other combinations and various improvements within the concept of the present invention may be carried out without departing from the gist or scope of the present invention.

[0027] The following is an exemplary description of the preparation process of the fluorinated hydroxyaminosilane used in the examples:

[0028] Fluorinated Hydroxylaminosilane-1

[0029] S1: Add 3.23g of vinyltrichlorosilane into a reaction vessel, add 30g of 1000 molecular weight hydroxyl-terminated perfluoropolyether alcohol (customized from Solvay, Italy) dropwise under 50°C oil bath while stirring, add dropwise for 2h, raise the temperature of the reaction system to 70°C for condensation reflux reaction, the condensation temperature is -10°C, until the pH of the system is 4.5-6.5, then stop heating;

[0030] S2: Add 1.9 g of diethanolamine and 50 ml of chloroform to the reaction system obtained in S1, carry out addition reaction for 5 hours, and then perform distillation separation and purification. First, collect the fraction at 75-80°C by atmospheric distillation, and then collect the target product by vacuum distillation at 75°C to obtain the fluorinated hydroxyaminosilane-1.

[0031] Fluorinated Hydroxylaminosilane-2

[0032] S1: Add 5g of acryltrifluorosilane into a reaction vessel, add 72g of 1000 molecular weight hydroxyl-terminated perfluoropolyether alcohol (customized from Solvay, Italy) dropwise under 60°C oil bath while stirring, add dropwise for 2h, raise the temperature of the reaction system to 70°C for condensation reflux reaction, the condensation temperature is -5°C, until the pH of the system is 4.5-6.5, then stop heating;

[0033] S2: Add 4.75 g of diethanolamine and 50 ml of chloroform to the reaction system obtained in S1, carry out addition reaction for 5 hours, and then perform distillation separation and purification. First, use atmospheric distillation to collect the 75-80°C fraction, and then use reduced pressure distillation at 85°C to collect the target product, thereby obtaining the fluorinated hydroxyaminosilane-2.

[0034] Fluorinated Hydroxylaminosilane-3

[0035] S1: 3.34 g of pentenyltribromosilane was added to a reaction vessel, and 33.75 g of 1500 molecular weight hydroxyl-terminated perfluoropolyether alcohol (customized from Solvay, Italy) was added dropwise under a 70°C oil bath while stirring for 3 hours. The temperature of the reaction system was raised to 80°C for condensation reflux reaction at a condensation temperature of 0°C until the pH of the system reached 4.5-6.5, and heating was stopped;

[0036] S2: Add 1.17 g of diethanolamine and 50 ml of chloroform to the reaction system obtained in S1, and carry out addition reaction for 5 hours, and then perform distillation separation and purification. First, use atmospheric distillation to collect the 75-80°C fraction, and then use reduced pressure distillation at 95°C to collect the target product, so as to obtain the fluorinated hydroxyaminosilane-3.

[0037] Fluorinated Hydroxylaminosilane-4

[0038] The preparation process is similar to that of fluorinated hydroxyaminosilane-3, except that the mass of the added terminal hydroxyl perfluoropolyether alcohol is 25 g.

[0039] Example 1

[0040] A hyperbranched TPU nanofiber waterproof breathable membrane, the preparation process of which is as follows: isophorone diisocyanate and fluorinated hydroxy aminosilane-1 are vacuum dehydrated, added into a reactor filled with nitrogen in a molar ratio of -N=C=O:-OH=2:0.5, methanol is added to dissolve, dibutyltin dilaurate accounting for 0.05wt% of the total reaction system mass is added, stirring and reacting at 40°C for 2h, removing methanol by reduced pressure distillation, and spinning into a membrane on a receiving matrix non-woven fabric by electrostatic spinning, wherein the spinning conditions are: an infusion speed of 1ml / h, a spinning voltage of 25kV, a spinning speed of 50r / min, a spinning temperature of 15°C, and a relative humidity of 30%, so as to obtain the hyperbranched TPU nanofiber waterproof and moisture permeable membrane.

[0041] Example 2

[0042] A hyperbranched TPU nanofiber waterproof breathable membrane, the preparation process of which is as follows: toluene diisocyanate and fluorinated hydroxy aminosilane-2 are vacuum dehydrated, added into a reactor filled with nitrogen in a molar ratio of -N=C=O:-OH=2:0.8, methanol is added to dissolve, dibutyltin dilaurate accounting for 0.06wt% of the total reaction system mass is added, stirring and reacting at 50°C for 2h, removing methanol by reduced pressure distillation, and spinning into a membrane on a receiving matrix aluminum foil by electrostatic spinning, wherein the spinning conditions are: a perfusion speed of 3ml / h, a spinning voltage of 40kV, a spinning speed of 80r / min, a spinning temperature of 20°C, and a relative humidity of 60%, so as to obtain the hyperbranched TPU nanofiber waterproof and moisture permeable membrane.

[0043] Example 3

[0044] A hyperbranched TPU nanofiber waterproof breathable membrane, the preparation process of which is as follows: hexamethylene diisocyanate and fluorinated hydroxyaminosilane-3 are vacuum dehydrated, added into a reactor filled with nitrogen in a molar ratio of -N=C=O:-OH=2:1, methanol is added to dissolve, dibutyltin dilaurate accounting for 0.08wt% of the total reaction system mass is added, stirring and reacting at 65°C for 3h, and then distilling under reduced pressure to remove methanol, and spinning into a membrane on a receiving matrix aluminum foil by electrostatic spinning, wherein the spinning conditions are: an infusion speed of 5ml / h, a spinning voltage of 50kV, a spinning speed of 100r / min, a spinning temperature of 30°C, and a relative humidity of 90%, so as to obtain the hyperbranched TPU nanofiber waterproof and moisture-permeable membrane.

[0045] Example 4

[0046] Similar to Example 3, except that the raw material used is fluorinated hydroxyaminosilane-4.

[0047] Comparative Example 1

[0048] Similar to Example 3, except that the fluorinated hydroxyaminosilane-3 is replaced by diethanolamine.

[0049] Performance Testing

[0050] The following performance tests were performed on the hyperbranched TPU nanofiber waterproof and breathable membranes obtained in Examples 1-4 and Comparative 1:

[0051] Water vapor permeability: Tested in accordance with GB / T 12704.2-2009 Test method for water vapor permeability of textile fabrics Part 2: Evaporation method;

[0052] Waterproofness: Tested in accordance with GB / T 4744-2013 Testing and evaluation of waterproof performance of textiles - Hydrostatic pressure method;

[0053] Elastic recovery rate: tested in accordance with "FZ / T 50007-2012 Test method for elasticity of spandex yarn".

[0054] The test results are detailed in Table 1:

[0055]

[0056] From the data in Table 1, it can be seen that the hyperbranched TPU nanofiber membrane provided by the present invention has excellent waterproof and moisture permeability. Under the national standard testing conditions, the moisture permeability can reach 9000g / (m 2 •24h), the hydrostatic pressure can reach more than 50kPa, and it has good resilience, and the elastic recovery rate can reach more than 85%. In Example 4, due to the change in the raw material ratio for preparing fluorinated hydroxyaminosilane, the halogen atoms in the system are not completely hydrolyzed and condensed, which affects the subsequent formation of the branched structure of the TPU polymer, thereby greatly reducing the moisture permeability and waterproofness of the obtained fiber membrane. In Comparative Example 1, the fluorinated hydroxyaminosilane provided by the present invention was not used, and only conventional TPU polymer was used to spin and prepare fiber membranes, and its performance was not as good as that of the fiber membrane obtained in the example.

[0057] In summary, the hyperbranched TPU nanofiber waterproof and breathable membrane provided by the present invention has excellent waterproof and breathable properties, good resilience, is not easily deformed during use, and has broad application prospects in the field of full heat exchangers.

Claims

1. A hyperbranched TPU nanofiber waterproof and breathable membrane, characterized in that: The silane is obtained by polymerizing diisocyanate and fluorinated hydroxyl aminosilane under the action of a catalyst and spinning, wherein the fluorinated hydroxyl aminosilane is prepared from terminal hydroxyl perfluoropolyether alcohol, diethanolamine and unsaturated halogenated silane; The preparation method of the fluorinated hydroxyaminosilane comprises the following steps: S1: Add unsaturated halogenated silane to a reaction vessel, add terminal hydroxyl perfluoropolyether alcohol dropwise under stirring in an oil bath at 50-70°C for 2-3h, raise the temperature of the reaction system to 70-80°C for condensation reflux reaction, the condensation temperature is -10-0°C, until the pH of the system is 4.5-6.5, then stop heating; S2: adding diethanolamine and organic solvent 1 to the reaction system obtained in S1 to carry out addition reaction, and then performing distillation separation and purification, firstly collecting the unreacted terminal hydroxyl perfluoropolyether alcohol and transition fraction by atmospheric distillation, and then collecting the target product by vacuum distillation to obtain the fluorinated hydroxyl aminosilane; Among them, in S1, the structure of the unsaturated halogenated silane is R-SiX3, wherein R is a C2-5 unsaturated olefin group, and X is F, Cl, Br, or I; The structure of the hydroxy-terminated perfluoropolyether alcohol is shown in Formula I: Formula I In formula I, n=4-7, m=6-10; the number average molecular weight of the hydroxyl-terminated perfluoropolyether alcohol is 1000-1500; The dosage of the unsaturated halogenated silane and the terminal hydroxyl perfluoropolyether alcohol satisfies that the molar ratio of -X:-OH is 1:1-1.5; the dosage of the unsaturated halogenated silane and diethanolamine satisfies that the molar ratio of -C=C-:-NH is 0.8-1:

1.

2. The hyperbranched TPU nanofiber waterproof and breathable membrane according to claim 1, characterized in that: The diisocyanate is at least one of isophorone diisocyanate, dicyclohexylmethane diisocyanate, toluene diisocyanate, 4,4′-diphenylmethane diisocyanate, 1,5-naphthalene diisocyanate and hexamethylene diisocyanate.

3. The hyperbranched TPU nanofiber waterproof and breathable membrane according to claim 1, characterized in that: The organic solvent 1 in S2 is at least one of chloroform, dichloromethane, ether, toluene, methanol, ethanol, and isopropanol.

4. The hyperbranched TPU nanofiber waterproof and breathable membrane according to claim 1, characterized in that: The atmospheric distillation in S2 collects the fraction at 75-80°C, and the reduced pressure distillation collects the fraction at 75-95°C.

5. The method for preparing the hyperbranched TPU nanofiber waterproof and breathable membrane according to any one of claims 1 to 4, characterized in that: The method comprises the following steps: vacuum dehydrating the diisocyanate and the fluorinated hydroxyl aminosilane, adding them into a reactor filled with inert gas according to a molar ratio of -N=C=O:-OH=2:0.5-1, adding an organic solvent 2 to dissolve them, adding a catalyst accounting for 0.05-0.08wt% of the total reaction system mass, stirring and reacting at 40-65°C for 2-3h, removing the organic solvent 2 by reduced pressure distillation, and spinning them into a film on a receiving matrix by electrostatic spinning to obtain the hyperbranched TPU nanofiber waterproof and moisture permeable film.

6. Application of the hyperbranched TPU nanofiber waterproof and breathable membrane according to any one of claims 1 to 4 in the field of total heat exchangers.

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