Waterborne polyurethane, emulsion containing waterborne polyurethane as well as preparation method and application of emulsion

Abstract

The invention belongs to the technical field of high polymer materials and coatings, and relates to waterborne polyurethane, an emulsion containing the waterborne polyurethane as well as a preparation method and application of the emulsion. The preparation method of the emulsion containing the waterborne polyurethane comprises the following steps: dehydrating the polytetrahydrofuran ether glycol in vacuum; then adding isophorone diisocyanate, dibutyltin dilaurate and butanone, and carrying out a heat preservation reaction to obtain a prepolymer; then adding 1, 4-butanediol, 3-dimethylamino-1, 2-propylene glycol, a defoaming agent, a dispersing agent and a flatting agent, and carrying out further heat preservation reaction; adding syringic acid and acetic acid for reaction; adding water to emulsify to obtain a waterborne polyurethane emulsion; according to the application, the emulsion is used for preparing the polyurethane moisture-permeable microporous membrane. The prepared polyurethane moisture-permeable microporous membrane has good water resistance, moisture permeability, antibacterial and antifouling properties and strength, and can meet the application requirements of multiple fields.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials and coatings, and relates to a waterborne polyurethane, an emulsion containing the waterborne polyurethane, and a preparation method and application thereof. Background Art

[0002] As people's living standards continue to improve, people's requirements for fabric performance continue to increase. Polyurethane waterproof and breathable membranes have excellent physical properties in both waterproofness and breathability, and are now widely used in the manufacture of windbreakers, cold-proof jackets, hats, bedspreads, etc.

[0003] Polyurethane waterproof and breathable membrane is a polymer film material with dual functions of waterproof and breathable. After lamination with textile fabrics, functional fabrics with both water permeability resistance and water vapor permeability can be prepared. Since the polyester / polyether segments or added additives in the polyurethane molecular chain can be used as carbon sources for microbial growth, polyurethane materials can cause bacterial growth and cross-infection at suitable wet temperatures, which not only shortens the service life of polyurethane materials, but also seriously threatens human health.

[0004] When preparing polyurethane waterproof and breathable membranes, waterborne polyurethane, as an important raw material, can give the film good waterproofness and breathability. By adjusting the formula and process conditions of waterborne polyurethane, polyurethane films with different waterproof and breathable properties can be prepared to meet the application needs of different fields. Based on waterborne polyurethane, cationic waterborne polyurethane, as a new type of polymer material, has gradually attracted people's attention.

[0005] Cationic waterborne polyurethanes contain a large number of cationic groups in their molecular structure. These cationic groups can interact with the cell membrane of microorganisms to destroy the structure and function of microorganisms, giving the material antibacterial ability. At present, cationic waterborne polyurethanes mainly use brominated alkanes with different alkyl chain lengths as quaternary ammonium salts with antibacterial function. For example, the literature (Antimicrobial Waterborne Polyurethanes Based on Quaternary Ammonium Compounds [J]. Industrial And Engineering Chemistry Research, 2020, 59 (1): 458-463.) introduces C 12 H 25Br is used as a quaternizing agent to form a quaternary ammonium salt with antibacterial function, but the introduction of a long alkyl chain will increase the gaps between molecules, weaken the interaction between molecules, and reduce the mechanical properties of the polyurethane waterproof and breathable membrane made therefrom; moreover, the halogens contained in the raw materials cause great environmental pollution, restricting the environmental friendliness of the polyurethane waterproof and breathable membrane; in addition, the long alkyl chain is not conducive to the formation of a good hydrophobic surface, resulting in a smaller water contact angle and poor hydrophobicity, and poor hydrophobicity will make stains more easily adhere to the membrane surface, which is difficult to be easily removed by water flow, etc., which in turn leads to poor antifouling properties of the polyurethane waterproof and breathable membrane.

[0006] Therefore, it is necessary to prepare a cationic waterborne polyurethane and a preparation method thereof that can solve the above problems, and to prepare a polyurethane moisture-permeable microporous membrane therefrom. Summary of the invention

[0007] The purpose of the present invention is to solve the problems existing in the prior art and to provide an aqueous polyurethane, an emulsion containing the aqueous polyurethane, and a preparation method and application thereof.

[0008] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0009] A waterborne polyurethane, the structural formula is as follows:

[0010]

[0011] Wherein, n is 20-100.

[0012] The present invention also provides an aqueous polyurethane emulsion, which contains the aqueous polyurethane as described above.

[0013] As the preferred technical solution:

[0014] The aqueous polyurethane emulsion as described above comprises the following components and contents, by weight: 10-20 parts of polytetramethylene ether glycol, 5-12 parts of isophorone diisocyanate, 1-8 parts of dibutyltin dilaurate, 27-31 parts of butanone, 3-10 parts of 1,4-butanediol, 1-10 parts of 3-dimethylamino-1,2-propylene glycol, 1-5 parts of defoaming agent, 1-5 parts of dispersant, 1-1.5 parts of leveling agent, 1-10 parts of syringic acid, 1-5 parts of acetic acid and 20-35 parts of water.

[0015] The present invention also provides a method for preparing an aqueous polyurethane emulsion as described in any one of the above items, comprising the following steps:

[0016] (A) placing polytetrahydrofuran ether diol in a reactor and dehydrating it in a vacuum; polytetrahydrofuran ether diol is hygroscopic, and vacuum dehydration can reduce the presence of oxygen and water, prevent oxidation reaction, and maintain the stability and quality of the product;

[0017] (B) After the temperature drops to 80-95° C., isophorone diisocyanate, dibutyltin dilaurate and butanone are added to the reactor, and the reaction is carried out for 1-5 hours at a temperature-keeping temperature to obtain a prepolymer; in this process, polytetrahydrofuran ether and isophorone diisocyanate react under the action of dibutyltin dilaurate catalyst; the addition of dibutyltin dilaurate can accelerate the reaction rate, generate a suitable acid value, and promote the reaction, making the synthesis process more efficient and stable; the addition of butanone can make the surface of the polyurethane film smooth and uniform, improve the appearance quality, and effectively control the viscosity of the polyurethane, thereby improving the wear resistance and strength of the polyurethane film;

[0018] (C) After the temperature drops to 70-85°C, 1,4-butanediol and 3-dimethylamino-1,2-propylene glycol are first added dropwise to the reactor, and then butanone, defoamer, dispersant and leveling agent are added, and the reaction is kept warm for 1-4 hours; 1,4-butanediol as a chain extender can adjust the ratio and molecular weight of the soft and hard segments of the polyurethane macromolecular chain; the addition of an appropriate amount of 3-dimethylamino-1,2-propylene glycol can adjust the hardness of the polyurethane and improve the wear resistance and heat resistance of the polyurethane film; butanone can make the surface of the polyurethane film smooth and uniform, and improve the appearance quality; defoamer, dispersant and leveling agent as additives can improve the film-forming property;

[0019] (D) After the temperature drops to 35-50° C., syringic acid and acetic acid are added to the reactor, and the reaction is kept warm for 1-5 hours; syringic acid is used as a tertiary ammonium reagent to replace traditional brominated alkanes, so that the polyurethane film has antibacterial and antifouling properties. Syringic acid introduces phenolic acid structures into the polymer molecular chain, providing a large number of hydrogen bond donors or acceptors, which is conducive to forming a dense cross-linked network, further improving the strength and hydrophobicity of the polyurethane film; acetic acid can increase the mixing degree between the reactants and enhance the uniformity of the polyurethane reaction system;

[0020] (E) After adding water into the reaction kettle and emulsifying, a waterborne polyurethane emulsion is obtained.

[0021] As the preferred technical solution:

[0022] In the above method, in step (A), the dehydration temperature is 100-120° C. and the dehydration time is 1-4 h.

[0023] In the method as described above, in step (E), the shear rate of emulsification is 10000-20000 r / min, and the time is 1-5 h.

[0024] The present invention also provides a polyurethane moisture-permeable microporous membrane, which is prepared by using the above-mentioned aqueous polyurethane emulsion.

[0025] As the preferred technical solution:

[0026] The polyurethane moisture permeable microporous membrane as described above is prepared by coating an aqueous polyurethane emulsion on a base film, drying both sides of the base film at the same time, and removing the base film to obtain the polyurethane moisture permeable microporous membrane. The specific steps are as follows:

[0027] (a) Install the base film on the coating machine and adjust the positions of the scraper, coating table and auxiliary heating frame;

[0028] (b) placing an appropriate amount of waterborne polyurethane emulsion on the scraper;

[0029] (c) starting the film coating station, and the scraper is pushed by the film coating station to coat the surface of the base film, thereby forming a layer of polyurethane wet film on the base film;

[0030] (d) When the coating reaches the specified length, the drying system inside the coating machine is started to heat and dry the bottom of the initial film after scraping. At the same time, the auxiliary heating frame is started to move back and forth above the initial film to heat and dry the top of the initial film. The upper and lower heating temperature sections are set to 125°C and 150°C respectively;

[0031] (e) After drying, remove the scraper, start the laminating table and the auxiliary heating frame, move them back to their original positions, turn off the coating machine, and remove the polyurethane moisture permeable microporous film on the base film;

[0032] The aqueous polyurethane emulsion of the present invention contains both water and butanone. During the drying process to form a polyurethane film, due to the large difference in polarity between the two, the volatility is also large, and when the two evaporate from the polyurethane phase, micropores will be left.

[0033] The prior art synthesizes polyurethane coating liquid and directly dries it during the process of preparing the coating liquid. The present invention combines a two-way drying system to make the liquid disperse evenly and quickly, which is beneficial to the formation of micropores in the polyurethane microporous membrane. The coating machine includes a control console and a support table. The control console is fixedly connected to the upper end of the support table. A vacuum suction cup is installed on the upper end of the support table. The drying system is installed inside the support table. The scraper, coating table and auxiliary heating frame are all located on the upper side of the vacuum suction cup, and the coating table is located between the scraper and the auxiliary heating frame. The coated silk film is dried from bottom to top by the drying system inside the support table, and the silk film is dried from top to bottom by the auxiliary heating frame. The two-way drying system is combined to make the liquid disperse evenly and quickly.

[0034] The polyurethane moisture permeable microporous membrane as described above has a thickness of 31-35 μm, a pore size of 1-5 μm, and an absolute value of square gram weight error of 0.1-0.3 g / m 2 , moisture permeability is 10000-12000g / (m 2·24h), hydrostatic pressure is 8000-9000mmH2O, tensile strength is 40-48MPa, water contact angle is 85-92°, sterilization rate for Escherichia coli is 98.3-99.6%, sterilization rate for Staphylococcus aureus is 98.3-99.7%, waterproof and breathable property is level three.

[0035] Beneficial effects:

[0036] (1) The present invention adopts syringic acid as a tertiary ammonium agent to replace traditional brominated alkanes, and successfully introduces antibacterial function into the molecular structure of waterborne polyurethane. Syringic acid not only has antibacterial properties, but also can introduce phenolic acid structure into the polymer molecular chain, providing a large number of hydrogen bond donors or acceptors, which is conducive to the formation of a dense cross-linked network, thereby further improving the strength and hydrophobicity of the polyurethane film. This structure enables the polyurethane breathable microporous membrane to maintain excellent waterproof and breathable properties while also having excellent antibacterial and antifouling properties, effectively extending the service life of the material and reducing the risk of cross infection caused by bacterial growth.

[0037] (2) The polyurethane moisture-permeable microporous membrane prepared by the present invention has better mechanical properties than the polyurethane membrane using long alkyl chain bromoalkane as the quaternizing agent.

[0038] (3) The present invention abandons the raw materials containing halogens, thus avoiding the problem of environmental pollution. As a natural product, the use of syringic acid not only meets the requirements of environmental protection, but also helps to promote green chemistry and sustainable development.

[0039] (4) In the process of preparing the aqueous polyurethane emulsion, the present invention ensures the stability and quality of the product by precisely controlling the proportion of each component and the reaction conditions. At the same time, a two-way drying system is combined to prepare the polyurethane moisture-permeable microporous membrane, so that the liquid can be evenly and quickly dissipated, which is beneficial to the formation of micropores and the optimization of membrane performance.

[0040] (5) The polyurethane moisture-permeable microporous membrane prepared by the present invention has good moisture permeability. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 The reaction equation for producing waterborne polyurethane in Example 1;

[0042] Figure 2 This is a front SEM of the polyurethane moisture-permeable microporous membrane of Example 1; wherein the magnification of a is 400, the magnification of b is 1000, and the magnification of c is 2000;

[0043] Figure 3 This is a cross-sectional SEM of the polyurethane moisture-permeable microporous membrane of Example 1; wherein the magnification of a is 400, the magnification of b is 1000, and the magnification of c is 2000;

[0044] Figure 4 This is the back SEM of the polyurethane moisture-permeable microporous membrane of Example 1; wherein the magnification of a is 400, the magnification of b is 1000, and the magnification of c is 2000. DETAILED DESCRIPTION

[0045] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0046] The following are the test methods for the relevant performance indicators in each embodiment and comparative example:

[0047] Absolute value of square gram weight error: Cut the polyurethane film into 20 pieces of 100 cm 2 Take samples, test the weight of each sample, and calculate the square gram weight of each sample. The difference between the maximum square gram weight and the minimum square gram weight is the absolute value of the square gram weight error.

[0048] Moisture permeability: measured in accordance with GBT12704.1-2009 standard.

[0049] Hydrostatic pressure: measured in accordance with JIS L1092-2009.

[0050] Tensile strength: measured in accordance with GBT1040.1-2018 standard; wherein the tensile speed is set to 200 mm / min.

[0051] Water contact angle: measured in accordance with GB / T30693-2014 standard.

[0052] Sterilization rate: measured in accordance with WST650-2019 standard.

[0053] Waterproof and moisture permeability: measured in accordance with GB / T40910-2021 standard.

[0054] In the following embodiments, the general structural formula of waterborne polyurethane is as follows:

[0055]

[0056] A method for preparing a polyurethane moisture-permeable microporous membrane, the specific steps are as follows:

[0057] (1) Preparation of raw materials;

[0058] Polytetramethylene glycol: the manufacturer is Shanghai Kangliang Chemical Co., Ltd., the number average molecular weight is 1000;

[0059] Isophorone diisocyanate;

[0060] Dibutyltin dilaurate;

[0061] Butanone;

[0062] 1,4-Butanediol;

[0063] 3-Dimethylamino-1,2-propanediol;

[0064] Defoaming agent: manufacturer is BYK Chemical Company, model number is BYK054;

[0065] Dispersant: manufacturer is BYK Chemical Company, model is BYK110;

[0066] Leveling agent: manufacturer is Evonik, model is TEGO1484;

[0067] Syringic acid;

[0068] Acetic acid;

[0069] water;

[0070] (2) Preparation of waterborne polyurethane emulsion (the reaction equation for forming waterborne polyurethane is as follows Figure 1 shown);

[0071] (2.1) Place polytetrahydrofuran ether diol in a reaction kettle and dehydrate it in vacuum at 120°C for 2 hours;

[0072] (2.2) After the temperature drops to 90° C., isophorone diisocyanate, dibutyltin dilaurate and butanone are added to the reaction kettle and the reaction is carried out at the temperature for 2 hours to obtain a prepolymer;

[0073] (2.3) After the temperature drops to 75°C, add 1,4-butanediol and 3-dimethylamino-1,2-propylene glycol dropwise into the reactor, then add butanone, defoamer, dispersant, and leveling agent, and keep the reaction warm for 2 hours;

[0074] (2.4) After the temperature drops to 45°C, syringic acid and acetic acid are added to the reactor and the reaction is carried out at the temperature for 2 hours to obtain waterborne polyurethane;

[0075] In the structural formula of waterborne polyurethane, n is 40;

[0076] (2.5) After adding water to the reactor, emulsification was performed at a shear rate of 12000 r / min for 2 h to obtain an aqueous polyurethane emulsion;

[0077] In steps (2.1) to (2.5), the mass ratio of butanone added for the second time to butanone added for the first time is 13:15;

[0078] The contents of the components in the aqueous polyurethane emulsion are as follows by weight: 12 parts of polytetramethylene glycol, 8 parts of isophorone diisocyanate, 3 parts of dibutyltin dilaurate, 28 parts of butanone, 6 parts of 1,4-butanediol, 5 parts of 3-dimethylamino-1,2-propylene glycol, 1 part of defoamer, 2 parts of dispersant, 1 part of leveling agent, 5 parts of syringic acid, 2 parts of acetic acid, and 27 parts of water;

[0079] (3) preparing a polyurethane moisture permeable microporous membrane;

[0080] After the water-based polyurethane emulsion is coated on the base film, both sides are dried at the same time, and the base film is removed to obtain the polyurethane moisture-permeable microporous membrane.

[0081] The SEM image of the front side of the polyurethane moisture permeable microporous membrane (the side with the base film removed is the back side and the other side is the front side) is as follows: Figure 2 As shown, cross-sectional SEM Figure 3 As shown, the back SEM Figure 4 As shown in the figure, the thickness of the polyurethane breathable microporous membrane is 33 μm, the pore size is 2.6 μm, and the absolute value of the square gram weight error is 0.3 g / m 2 , moisture permeability is 10600g / (m 2 ·24h), hydrostatic pressure is 8500mmH2O, tensile strength is 42.2MPa, water contact angle is 87°, sterilization rate for Escherichia coli is 99.1%, sterilization rate for Staphylococcus aureus is 99.5%, waterproof and breathable property is level three.

[0082] Comparative Example 1

[0083] A method for preparing a polyurethane film is basically the same as in Example 1, except that syringic acid is replaced by an equal mass of C 12 H 25 Br.

[0084] The tensile strength of the polyurethane film finally prepared was 33.7 MPa and the water contact angle was 64°.

[0085] Compared with Example 1, the hydrophobicity and strength of the polyurethane film in Comparative Example 1 are significantly worse. This is because Comparative Example 1 uses C 12 H 25 Br is used as a quaternizing agent. The introduction of long alkyl chains will increase the gaps between molecules, weaken the interaction between molecules, and reduce the mechanical properties of the polyurethane film. At the same time, long alkyl chains are not conducive to the formation of a good hydrophobic surface, resulting in a smaller water contact angle and worse hydrophobicity.

[0086] Example 2

[0087] A method for preparing a polyurethane moisture-permeable microporous membrane is basically the same as that of Example 1, except that in steps (2.1) to (2.5), the mass ratio of butanone added for the second time to butanone added for the first time is 13:18, and the content of butanone in the prepared aqueous polyurethane emulsion is 31 parts.

[0088] The thickness of the polyurethane moisture permeable microporous membrane was 33 μm, the pore size was 2.5 μm, and the absolute value of the square gram weight error was 0.15 g / m 2 , moisture permeability is 10800g / (m 2 ·24h), hydrostatic pressure is 8700mmH2O, tensile strength is 42.4MPa, water contact angle is 87°, sterilization rate for Escherichia coli is 99.1%, sterilization rate for Staphylococcus aureus is 99.5%, waterproof and breathable property is level three.

[0089] Example 3

[0090] A method for preparing a polyurethane moisture-permeable microporous membrane is basically the same as that of Example 1, except that the content of syringic acid in the aqueous polyurethane emulsion prepared in step (2) is 6 parts.

[0091] The thickness of the polyurethane breathable microporous membrane was 32 μm, the pore size was 2.4 μm, and the absolute value of the square gram weight error was 0.15 g / m 2 , moisture permeability is 10800g / (m 2 ·24h), hydrostatic pressure is 8600mmH2O, tensile strength is 43.6MPa, water contact angle is 87°, sterilization rate for Escherichia coli is 99.1%, sterilization rate for Staphylococcus aureus is 99.5%, waterproof and breathable property is level three.

[0092] Example 4

[0093] A method for preparing a polyurethane moisture-permeable microporous membrane is basically the same as that of Example 1, except that the content of syringic acid in the aqueous polyurethane emulsion prepared in step (2) is 7 parts and the content of water is 23 parts.

[0094] The thickness of the polyurethane moisture permeable microporous membrane was 32 μm, the pore size was 2.3 μm, and the absolute value of the square gram weight error was 0.15 g / m 2 , moisture permeability is 10900g / (m 2 ·24h), hydrostatic pressure is 8800mmH2O, tensile strength is 44.5MPa, water contact angle is 87°, sterilization rate for Escherichia coli is 99.1%, sterilization rate for Staphylococcus aureus is 99.5%, waterproof and breathable property is level three.

[0095] Example 5

[0096] A method for preparing a polyurethane moisture-permeable microporous membrane is basically the same as that of Example 1, except that the content of the defoamer in the aqueous polyurethane emulsion prepared in step (2) is 1.5 parts, the content of the dispersant is 2.5 parts, and the content of the leveling agent is 1 part.

[0097] The thickness of the polyurethane breathable microporous membrane was 33 μm, the pore size was 2.6 μm, and the absolute value of the square gram weight error was 0.25 g / m 2 , moisture permeability is 10600g / (m 2 ·24h), hydrostatic pressure is 8500mmH2O, tensile strength is 42.5MPa, water contact angle is 87°, sterilization rate for Escherichia coli is 99.1%, sterilization rate for Staphylococcus aureus is 99.5%, waterproof and breathable property is level three.

[0098] Example 6

[0099] A method for preparing a polyurethane moisture-permeable microporous membrane is basically the same as that of Example 1, except that the content of the defoamer in the aqueous polyurethane emulsion prepared in step (2) is 1.5 parts, the content of the dispersant is 2 parts, and the content of the leveling agent is 1.5 parts.

[0100] The thickness of the polyurethane breathable microporous membrane was 32 μm, the pore size was 2.6 μm, and the absolute value of the square gram weight error was 0.2 g / m 2 , moisture permeability is 10800g / (m 2 ·24h), hydrostatic pressure is 8400mmH2O, tensile strength is 42.5MPa, water contact angle is 87°, sterilization rate for Escherichia coli is 99.1%, sterilization rate for Staphylococcus aureus is 99.5%, waterproof and breathable property is level three.

[0101] Example 7

[0102] A method for preparing a polyurethane moisture-permeable microporous membrane is basically the same as that of Example 1, except that the content of the defoamer in the aqueous polyurethane emulsion prepared in step (2) is 1 part, the content of the dispersant is 2.5 parts, and the content of the leveling agent is 1.5 parts.

[0103] The thickness of the polyurethane moisture permeable microporous membrane was 32 μm, the pore size was 2.5 μm, and the absolute value of the square gram weight error was 0.2 g / m 2 , moisture permeability is 10900g / (m 2 ·24h), hydrostatic pressure is 8600mmH2O, tensile strength is 42.6MPa, water contact angle is 87°, sterilization rate for Escherichia coli is 99.1%, sterilization rate for Staphylococcus aureus is 99.5%, waterproof and breathable property is level three.

[0104] Example 8

[0105] A method for preparing a polyurethane moisture-permeable microporous membrane is basically the same as that of Example 1, except that the content of the defoamer in the aqueous polyurethane emulsion prepared in step (2) is 1.5 parts, the content of the dispersant is 2.5 parts, and the content of the leveling agent is 1.5 parts.

[0106] The thickness of the polyurethane moisture permeable microporous membrane was 31 μm, the pore size was 2.4 μm, and the absolute value of the square gram weight error was 0.2 g / m 2 , moisture permeability is 11100g / (m 2 ·24h), hydrostatic pressure is 8500mmH2O, tensile strength is 42.7MPa, water contact angle is 87°, sterilization rate for Escherichia coli is 99.1%, sterilization rate for Staphylococcus aureus is 99.5%, waterproof and breathable property is level three.

[0107] Example 9

[0108] A method for preparing a polyurethane moisture-permeable microporous membrane, the specific steps are as follows:

[0109] (1) Preparation of raw materials;

[0110] Polytetramethylene glycol: the manufacturer is Shanghai Kangliang Chemical Co., Ltd., the number average molecular weight is 1000;

[0111] Isophorone diisocyanate;

[0112] Dibutyltin dilaurate;

[0113] Butanone;

[0114] 1,4-Butanediol;

[0115] 3-Dimethylamino-1,2-propanediol;

[0116] Defoaming agent: manufacturer is BYK Chemical Company, model number is BYK054;

[0117] Dispersant: manufacturer is BYK Chemical Company, model is BYK110;

[0118] Leveling agent: manufacturer is Evonik, model is TEGO1484;

[0119] Syringic acid;

[0120] Acetic acid;

[0121] water;

[0122] (2) preparing an aqueous polyurethane emulsion;

[0123] (2.1) Place polytetrahydrofuran ether diol in a reaction kettle and dehydrate it in vacuum at 100°C for 1 hour;

[0124] (2.2) After the temperature drops to 80° C., isophorone diisocyanate, dibutyltin dilaurate and butanone are added to the reaction kettle and the reaction is carried out at the temperature for 1 hour to obtain a prepolymer;

[0125] (2.3) After the temperature drops to 70°C, add 1,4-butanediol and 3-dimethylamino-1,2-propylene glycol dropwise into the reactor, then add butanone, defoamer, dispersant, and leveling agent, and keep the reaction warm for 1 hour;

[0126] (2.4) After the temperature drops to 35°C, syringic acid and acetic acid are added to the reactor and the reaction is kept at this temperature for 1 hour to obtain waterborne polyurethane;

[0127] In the structural formula of waterborne polyurethane, n is 20;

[0128] (2.5) After adding water to the reactor, emulsification was carried out at a shear rate of 10000 r / min for 1 h to obtain an aqueous polyurethane emulsion;

[0129] In steps (2.1) to (2.5), the mass ratio of butanone added for the second time to butanone added for the first time is 12:15;

[0130] The contents of each component in the aqueous polyurethane emulsion are as follows by weight: 10 parts of polytetramethylene glycol, 5 parts of isophorone diisocyanate, 1 part of dibutyltin dilaurate, 27 parts of butanone, 3 parts of 1,4-butanediol, 1 part of 3-dimethylamino-1,2-propylene glycol, 1 part of defoamer, 1 part of dispersant, 1.5 parts of leveling agent, 2 parts of syringic acid, 1 part of acetic acid, and 20 parts of water;

[0131] (3) preparing a polyurethane moisture permeable microporous membrane;

[0132] After the water-based polyurethane emulsion is coated on the base film, both sides are dried at the same time, and the base film is removed to obtain the polyurethane moisture-permeable microporous membrane.

[0133] The thickness of the polyurethane breathable microporous membrane was 30 μm, the pore size was 1 μm, and the absolute value of the square gram weight error was 0.1 g / m 2 , moisture permeability is 12000g / (m 2 ·24h), hydrostatic pressure is 8000mmH2O, tensile strength is 40.3MPa, water contact angle is 85°, sterilization rate for Escherichia coli is 98.3%, sterilization rate for Staphylococcus aureus is 98.3%, waterproof and breathable property is level three.

[0134] Example 10

[0135] A method for preparing a polyurethane moisture-permeable microporous membrane, the specific steps are as follows:

[0136] (1) Preparation of raw materials;

[0137] Polytetramethylene glycol: the manufacturer is Shanghai Kangliang Chemical Co., Ltd., the number average molecular weight is 1000;

[0138] Isophorone diisocyanate;

[0139] Dibutyltin dilaurate;

[0140] Butanone;

[0141] 1,4-Butanediol;

[0142] 3-Dimethylamino-1,2-propanediol;

[0143] Defoaming agent: manufacturer is BYK Chemical Company, model number is BYK054;

[0144] Dispersant: manufacturer is BYK Chemical Company, model is BYK110;

[0145] Leveling agent: manufacturer is Evonik, model is TEGO1484;

[0146] Syringic acid;

[0147] Acetic acid;

[0148] water;

[0149] (2) preparing an aqueous polyurethane emulsion;

[0150] (2.1) Place polytetrahydrofuran ether diol in a reaction kettle and dehydrate it in vacuum at 110°C for 3 hours;

[0151] (2.2) After the temperature drops to 92° C., isophorone diisocyanate, dibutyltin dilaurate and butanone are added to the reaction kettle and the reaction is carried out at the temperature for 3 hours to obtain a prepolymer;

[0152] (2.3) After the temperature drops to 80°C, add 1,4-butanediol and 3-dimethylamino-1,2-propylene glycol dropwise into the reactor, then add butanone, defoamer, dispersant, and leveling agent, and keep the reaction warm for 3 hours;

[0153] (2.4) After the temperature drops to 47°C, syringic acid and acetic acid are added to the reactor and the reaction is kept warm for 3 hours to obtain waterborne polyurethane;

[0154] In the structural formula of waterborne polyurethane, n is 65;

[0155] (2.5) After adding water to the reactor, emulsification was carried out at a shear rate of 15000 r / min for 3 h to obtain an aqueous polyurethane emulsion;

[0156] In steps (2.1) to (2.5), the mass ratio of butanone added for the second time to butanone added for the first time is 14:15;

[0157] The contents of each component in the aqueous polyurethane emulsion are as follows by weight: 15 parts of polytetramethylene glycol, 10 parts of isophorone diisocyanate, 5 parts of dibutyltin dilaurate, 29 parts of butanone, 8 parts of 1,4-butanediol, 7 parts of 3-dimethylamino-1,2-propylene glycol, 3 parts of defoamer, 3 parts of dispersant, 1.5 parts of leveling agent, 7 parts of syringic acid, 3 parts of acetic acid, and 30 parts of water;

[0158] (3) preparing a polyurethane moisture permeable microporous membrane;

[0159] After the water-based polyurethane emulsion is coated on the base film, both sides are dried at the same time, and the base film is removed to obtain the polyurethane moisture-permeable microporous membrane.

[0160] The thickness of the polyurethane moisture permeable microporous membrane was 34 μm, the pore size was 3.5 μm, and the absolute value of the square gram weight error was 0.2 g / m 2 , moisture permeability is 10300g / (m 2 ·24h), hydrostatic pressure is 8700mmH2O, tensile strength is 44.6MPa, water contact angle is 89°, sterilization rate for Escherichia coli is 99.3%, sterilization rate for Staphylococcus aureus is 99.6%, waterproof and breathable property is level three.

[0161] Embodiment 11

[0162] A method for preparing a polyurethane moisture-permeable microporous membrane, the specific steps are as follows:

[0163] (1) Preparation of raw materials;

[0164] Polytetramethylene glycol: the manufacturer is Shanghai Kangliang Chemical Co., Ltd., the number average molecular weight is 1000;

[0165] Isophorone diisocyanate;

[0166] Dibutyltin dilaurate;

[0167] Butanone;

[0168] 1,4-Butanediol;

[0169] 3-Dimethylamino-1,2-propanediol;

[0170] Defoaming agent: manufacturer is BYK Chemical Company, model number is BYK054;

[0171] Dispersant: manufacturer is BYK Chemical Company, model is BYK110;

[0172] Leveling agent: manufacturer is Evonik, model is TEGO1484;

[0173] Syringic acid;

[0174] Acetic acid;

[0175] water;

[0176] (2) preparing an aqueous polyurethane emulsion;

[0177] (2.1) Place polytetrahydrofuran ether diol in a reaction kettle and dehydrate it in vacuum at 120°C for 4 hours;

[0178] (2.2) After the temperature drops to 95° C., isophorone diisocyanate, dibutyltin dilaurate and butanone are added to the reaction kettle and the reaction is carried out at the temperature for 4 hours to obtain a prepolymer;

[0179] (2.3) After the temperature drops to 85°C, add 1,4-butanediol and 3-dimethylamino-1,2-propylene glycol dropwise into the reactor, then add butanone, defoamer, dispersant, and leveling agent, and keep the reaction warm for 4 hours;

[0180] (2.4) After the temperature drops to 50°C, syringic acid and acetic acid are added to the reactor and the reaction is carried out at the temperature for 5 hours to obtain waterborne polyurethane;

[0181] In the structural formula of waterborne polyurethane, n is 100;

[0182] (2.5) After adding water to the reactor, emulsification was carried out at a shear rate of 20,000 r / min for 5 h to obtain an aqueous polyurethane emulsion;

[0183] In steps (2.1) to (2.5), the mass ratio of butanone added for the second time to butanone added for the first time is 15:14;

[0184] The contents of the components in the aqueous polyurethane emulsion are as follows by weight: 20 parts of polytetramethylene glycol, 12 parts of isophorone diisocyanate, 8 parts of dibutyltin dilaurate, 29 parts of butanone, 10 parts of 1,4-butanediol, 10 parts of 3-dimethylamino-1,2-propylene glycol, 5 parts of defoamer, 5 parts of dispersant, 1.5 parts of leveling agent, 10 parts of syringic acid, 5 parts of acetic acid, and 35 parts of water;

[0185] (3) preparing a polyurethane moisture permeable microporous membrane;

[0186] After the water-based polyurethane emulsion is coated on the base film, both sides are dried at the same time, and the base film is removed to obtain the polyurethane moisture-permeable microporous membrane.

[0187] The thickness of the polyurethane breathable microporous membrane was 35 μm, the pore size was 5 μm, and the absolute value of the square gram weight error was 0.3 g / m 2, moisture permeability is 10000g / (m 2 ·24h), hydrostatic pressure is 9000mmH2O, tensile strength is 47.5MPa, water contact angle is 92°, sterilization rate for Escherichia coli is 99.6%, sterilization rate for Staphylococcus aureus is 99.7%, waterproof and breathable property is level three.

Claims

1. A waterborne polyurethane, characterized in that: The structural formula is as follows: Wherein, n is 20-100.

2. An aqueous polyurethane emulsion, characterized in that: Contains a waterborne polyurethane as claimed in claim 1.

3. An aqueous polyurethane emulsion according to claim 2, characterized in that: In terms of weight, the components and their contents are: 10-20 parts of polytetramethylene glycol, 5-12 parts of isophorone diisocyanate, 1-8 parts of dibutyltin dilaurate, 27-31 parts of butanone, 3-10 parts of 1,4-butanediol, 1-10 parts of 3-dimethylamino-1,2-propylene glycol, 1-5 parts of defoaming agent, 1-5 parts of dispersant, 1-1.5 parts of leveling agent, 1-10 parts of syringic acid, 1-5 parts of acetic acid, and 20-35 parts of water.

4. A method for preparing an aqueous polyurethane emulsion as claimed in claim 3, characterized in that: The following steps are involved: (A) polytetrahydrofuran ether glycol is placed in a reaction kettle and dehydrated in a vacuum; (B) After the temperature drops to 80-95° C., isophorone diisocyanate, dibutyltin dilaurate and butanone are added to the reaction kettle, and the mixture is kept warm for 1-5 hours to obtain a prepolymer; (C) After the temperature drops to 70-85°C, 1,4-butanediol and 3-dimethylamino-1,2-propylene glycol are added dropwise to the reaction kettle, followed by butanone, defoamer, dispersant and leveling agent, and the reaction is kept warm for 1-4 hours; (D) After the temperature drops to 35-50° C., syringic acid and acetic acid are added to the reaction kettle and the reaction is kept at this temperature for 1-5 hours; (E) After adding water into the reaction kettle and emulsifying, a water-based polyurethane emulsion is obtained.

5. The method according to claim 4, characterized in that In step (A), the dehydration temperature is 100-120° C. and the dehydration time is 1-4 h.

6. The method according to claim 4, characterized in that In step (E), the emulsification shear rate is 10000-20000 r / min, and the time is 1-5 h.

7. A polyurethane moisture permeable microporous membrane, characterized in that: It is prepared by using the aqueous polyurethane emulsion as claimed in claim 3.

8. A polyurethane moisture permeable microporous membrane according to claim 7, characterized in that: The preparation process is as follows: after coating the water-based polyurethane emulsion on the base film, drying both sides at the same time, removing the base film, and obtaining the polyurethane moisture-permeable microporous membrane.

9. A polyurethane moisture permeable microporous membrane according to claim 7, characterized in that: The thickness of the polyurethane breathable microporous membrane is 31-35μm, the pore size is 1-5μm, and the absolute value of the square gram weight error is 0.1-0.3g / m 2 , moisture permeability is 10000-12000g / (m 2 ·24h), hydrostatic pressure is 8000-9000mmH2O, tensile strength is 40-48MPa, water contact angle is 85-92°, sterilization rate for Escherichia coli is 98.3-99.6%, sterilization rate for Staphylococcus aureus is 98.3-99.7%, waterproof and breathable property is level three.

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