Preparation method of waterproof and moisture permeable fabric

Abstract

The invention discloses a preparation method of a waterproof and moisture-permeable fabric, and belongs to the technical field of waterproof and moisture-permeable fabrics, the preparation method of the waterproof and moisture-permeable fabric comprises the following steps: preparation of a surface layer fiber membrane, preparation of a moisture-permeable layer fiber membrane, and hot press molding; the preparation method of the surface layer fiber membrane comprises the steps of preparing a primary surface layer fiber membrane and performing heat treatment. The waterproof and moisture permeable fabric prepared by the method has excellent waterproof and moisture permeable performance, the surface can reach a super hydrophobic state, the static contact angle is 158.1-158.7 degrees, the hydrostatic pressure is 61-63 kPa, and the moisture permeable rate is 8250-8310 g / (m < 2 >. 24 h); after 20 times of complete standard household washing and drying, the waterproof and moisture permeable performance is kept good, the static contact angle is 150.6-151.4 degrees, the hydrostatic pressure is 54-56 kPa, and the moisture permeable rate is 8130-8220 g / (m < 2 >. 24 h).

Description

Technical Field

[0001] The present invention belongs to the technical field of waterproof and moisture-permeable fabrics, and particularly relates to a preparation method of a waterproof and moisture-permeable fabric. Background Art

[0002] Waterproof and moisture-permeable fabrics have the characteristics of allowing water vapor to pass through while preventing water, rain, snow, etc. from penetrating, and have received extensive attention and applications in clothing accessories, raincoats, and other aspects, becoming one of the research hotspots in the textile industry. Waterproof and moisture-permeable fabrics can prevent the penetration of water under a certain water pressure, protect the human body from the invasion of wind, rain, and snow, keep the clothing comfortable and dry, and the sweat emitted by the human body can diffuse to the outside in the form of water vapor through micropores.

[0003] According to the processing method, waterproof and moisture-permeable fabrics can be divided into three categories: high-density or ultra-high-density waterproof and moisture-permeable fabrics, laminated composite waterproof and moisture-permeable fabrics, and coated waterproof and moisture-permeable fabrics. Among them, laminated composite waterproof and moisture-permeable fabrics are prepared by laminating a waterproof and moisture-permeable film to a base fabric through hot melt adhesive or other adhesives under appropriate conditions such as hot pressing temperature, pressure, and hot roller laminating speed. Laminated composite waterproof and moisture-permeable fabrics make use of the advantages and avoid the disadvantages of two or more materials, enabling the excellent properties of the materials to be concentrated in one, and realizing the superposition and enhancement of functions.

[0004] Currently, the main methods for producing waterproof and moisture-permeable films on the market include processes such as biaxial stretching, melt extrusion, flash evaporation, and phase separation. However, most of the current waterproof and moisture-permeable films use fluorine-containing raw materials, which are not easily degradable and have the characteristics of long-distance migration, posing a serious threat to human health and environmental protection.

[0005] To avoid the harm caused by the use of fluorine-containing raw materials to human health and environmental protection, CN111019332B discloses a polyurethane waterproof and moisture-permeable film and its preparation method. The polyurethane waterproof and moisture-permeable film is made of raw materials with the following weight components: 25-45 parts of polyurethane resin, 52-75 parts of organic solvent, 0.5-2 parts of pore-forming agent, and 0.1-1 part of inorganic filler; the invention uses metal oxide porous microspheres as the pore-forming agent, and the number and diameter of the micropores in the porous microspheres can be adjusted, thereby enabling the regulation of the waterproof and moisture-permeable properties of the polyurethane film; the polyurethane resin in the invention contains hydrophilic polyether polyol, and the surface of the metal oxide porous microspheres is rich in polar hydroxyl groups, both of which increase the affinity for water and improve the moisture permeability. However, at the same time, it is easy for water droplets to adhere to the film surface, and combined with the siphon effect of the pores, the waterproof performance of the film will be reduced; at the same time, after multiple washes, the pore-forming agent and inorganic filler are easy to fall off under the action of mechanical force, resulting in a decrease in waterproof and moisture-permeable performance. Summary of the Invention

[0006] In view of the deficiencies of the prior art, the present invention provides a method for preparing a waterproof and moisture-permeable fabric. The waterproof and moisture-permeable fabric prepared by this method has excellent waterproof and moisture-permeable properties, can achieve long-term waterproof and moisture-permeable performance, and maintains good waterproof and moisture-permeable performance after multiple washing and drying processes.

[0007] To solve the above technical problems, the technical solutions adopted by the present invention are as follows: A method for preparing a waterproof and moisture-permeable fabric, comprising the following steps: preparation of a surface fiber membrane, preparation of a moisture-permeable layer fiber membrane, and hot pressing and forming; (1) The method for preparing the surface fiber membrane includes preparing a primary surface fiber membrane and heat treatment; The method for preparing the primary surface fiber membrane is to dissolve polyurethane and polycaprolactone in a mixed solvent composed of dimethylacetamide and dichloroethane, then add polymethylsilsesquioxane and polyvinyl formal, mix evenly, stand for 2 - 3 h, defoam to obtain a surface spinning solution, and perform electrospinning with the spinning solution at a spinning voltage of 12 - 15 kV. The spinning environment temperature is 25 - 30 °C to obtain a primary surface fiber membrane; The mass ratio of polyurethane, polycaprolactone, mixed solvent, polymethylsilsesquioxane, and polyvinyl formal in the surface spinning solution is 15:3 - 4:100 - 120:1.5 - 2.5:0.3 - 0.4; The polyurethane is composed of polyether-type polyurethane and polyester-type polyurethane, and the mass ratio of polyether-type polyurethane to polyester-type polyurethane is 3:1 - 1.2; The number-average molecular weight of the polyether-type polyurethane is 1500 - 2000, and the number-average molecular weight of the polyester-type polyurethane is 1500 - 2000; The number-average molecular weight of the polycaprolactone is 2000 - 3000; The number-average molecular weight of the polymethylsilsesquioxane is 4000 - 5000; The mass ratio of dimethylacetamide to dichloroethane in the mixed solvent is 1:1 - 1.5; The method for heat treatment is to perform heat treatment on the primary surface fiber membrane in a nitrogen atmosphere. The heat treatment temperature is 120 - 130 °C; the treatment time is 20 - 30 min. After the treatment is completed, a surface fiber membrane is obtained; The thickness of the surface fiber membrane is 10 - 15 μm.

[0008] (2) The method for preparing the moisture-permeable layer fiber membrane includes preparing a polyurethane emulsion, preparing a primary moisture-permeable layer fiber membrane, and heat cross-linking treatment; The method for preparing the polyurethane emulsion is as follows: The oligomer mixture of polybutylene glycol, polycaprolactam, and polycaprolactone diol is dried under vacuum at 80 - 90 °C, then stannous octoate as a catalyst is added. Diphenylmethane - 4,4'-diisocyanate is added at 60 - 70 °C, and then a prepolymer is prepared by reacting at 50 - 55 °C for 3 - 4 h. Acetone solvent is added for dissolution and dilution. At 50 - 55 °C, triethylamine is added for neutralization reaction for 2 - 2.5 h. Then diethylaminoethanol and water are added, and stirring is carried out at a speed of 800 - 1000 rpm for water emulsification and chain extension. Then the solvent is removed under vacuum to obtain a polyurethane emulsion with a solid mass fraction of 30 - 35%; The number - average molecular weight of the polybutylene glycol is 1000 - 2000; The number - average molecular weight of the polycaprolactam is 1000 - 2000; The number - average molecular weight of the polycaprolactone diol is 1000 - 2000; The mass ratio of diphenylmethane - 4,4'-diisocyanate, polybutylene glycol, polycaprolactam, and polycaprolactone diol is 16:10 - 12:3 - 4:3 - 4; The mass ratio of diphenylmethane - 4,4'-diisocyanate and stannous octoate is 16:0.1 - 0.15; The mass ratio of diphenylmethane - 4,4'-diisocyanate and acetone is 16:20 - 25; The mass ratio of diphenylmethane - 4,4'-diisocyanate and triethylamine is 16:4 - 5; The mass ratio of diphenylmethane - 4,4'-diisocyanate, diethylaminoethanol, and water is 16:1.5 - 2:80 - 90; The method for preparing the primary moisture - permeable layer fiber membrane is as follows: The polyurethane emulsion is diluted into a 15 - 20 wt% polyurethane aqueous solution, polyethylene glycol is dissolved in water to prepare a 10 - 15 wt% polyethylene glycol aqueous solution. The polyurethane aqueous solution and the polyethylene glycol aqueous solution are mixed, allowed to stand and defoamed to prepare a moisture - permeable layer spinning solution. The spinning solution is electrospun using the spinning liquid at a spinning voltage of 12 - 15 kV, and the spinning environment temperature is 25 - 30 °C to obtain a primary moisture - permeable layer fiber membrane; The number - average molecular weight of the polyethylene glycol is 5000 - 6000; The mass ratio of the polyurethane aqueous solution to the polyethylene glycol aqueous solution in the moisture - permeable layer spinning solution is 10:1.5 - 2; The thickness of the moisture - permeable layer fiber membrane is 30 - 40 μm.

[0009] Thermal cross - linking treatment: The primary moisture - permeable layer fiber membrane is subjected to thermal cross - linking treatment in a nitrogen atmosphere. The heat treatment temperature is 130 - 140 °C; the treatment time is 25 - 30 min. After the treatment is completed, a moisture - permeable layer fiber membrane is obtained.

[0010] (3) The preparation method of the hot pressing and forming is as follows: Lay the moisture-permeable layer fiber membrane flatly and superimposed on the base fabric, and then lay the surface layer fiber membrane flatly and superimposed on the moisture-permeable layer fiber membrane. Move it to a hot press for hot pressing and forming. Set the hot pressing time to 30 - 40 s and the hot pressing temperature to 100 - 110 °C to obtain a waterproof and moisture-permeable fabric; The base fabric is a non-woven fabric; The base fabric is a porous breathable fabric.

[0011] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The waterproof and moisture-permeable fabric prepared by the method of the present invention has excellent waterproof and moisture-permeable properties, and the surface can reach the superhydrophobic state, with a static contact angle of 158.1 - 158.7°, a hydrostatic pressure of 61 - 63 kPa, and a moisture permeability of 8250 - 8310 g / (m 2 ·24 h); (2) The waterproof and moisture-permeable fabric prepared by the method of the present invention can achieve long-term waterproof and moisture permeability. After multiple washing and drying, the waterproof and moisture-permeable properties remain good. After 20 complete standard household washing procedures, the static contact angle is 150.6 - 151.4°, the hydrostatic pressure is 54 - 56 kPa, and the moisture permeability is 8130 - 8220 g / (m 2 ·24 h). Detailed implementation manners

[0012] In order to have a clearer understanding of the technical features, objectives, and effects of the present invention, the specific implementation manners of the present invention are described below.

[0013] Example 1 A preparation method of a waterproof and moisture-permeable fabric It includes the following steps: (1) Prepare the surface layer fiber membrane A. Prepare the primary surface layer fiber membrane Dissolve 15 g of polyurethane and 3 g of polycaprolactone in a mixed solvent composed of 100 g of dimethylacetamide and dichloroethane. Then add 1.5 g of polymethylsilsesquioxane and 0.3 g of polyvinyl formal. After mixing evenly, let it stand for 2 h to remove bubbles to obtain a surface layer spinning solution. Use the surface layer spinning solution for electrospinning at a spinning voltage of 12 kV, and the spinning environment temperature is 25 °C to obtain a primary surface layer fiber membrane; The polyurethane is composed of polyether-type polyurethane and polyester-type polyurethane, and the mass ratio of polyether-type polyurethane to polyester-type polyurethane is 3:1; The number average molecular weight of the polyether-type polyurethane is 1500, and the number average molecular weight of the polyester-type polyurethane is 1500; The number average molecular weight of the polycaprolactone is 2000; The number-average molecular weight of the polymethylsilsesquioxane is 4,000; The mass ratio of dimethylacetamide to dichloroethane in the mixed solvent is 1:1.

[0014] B. Heat treatment The primary surface layer fiber membrane is heat-treated in a nitrogen atmosphere at a heat treatment temperature of 120 °C; the treatment time is 20 min, and after the treatment is completed, the surface layer fiber membrane is obtained; The thickness of the surface layer fiber membrane is 10 μm.

[0015] (2) Preparation of the moisture-permeable layer fiber membrane A. Preparation of the polyurethane emulsion The oligomer mixture of 10 g of polybutylene glycol, 3 g of polycaprolactam, and 3 g of polycaprolactone diol is vacuum-dried at 80 °C, then 0.1 g of stannous octoate catalyst is added, 16 g of diphenylmethane-4,4'-diisocyanate is added at 60 °C, and then the reaction is carried out at 50 °C for 3 h to obtain a prepolymer. 20 g of acetone solvent is added for dissolution and dilution. At 50 °C, 4 g of triethylamine is added for neutralization reaction for 2 h, then 1.5 g of diethylaminoethanol and 80 g of water are added and stirred at 800 rpm for water emulsification and chain extension, and then the solvent is removed by vacuum to obtain a polyurethane emulsion with a solid mass fraction of 30%; The number-average molecular weights of the polybutylene glycol, polycaprolactam, and polycaprolactone diol are all 1,000.

[0016] B. Preparation of the primary moisture-permeable layer fiber membrane The polyurethane emulsion is diluted into a 15 wt% polyurethane aqueous solution, polyethylene glycol is dissolved in water to prepare a 10 wt% polyethylene glycol aqueous solution, the polyurethane aqueous solution and the polyethylene glycol aqueous solution are mixed, and after standing and defoaming, a moisture-permeable layer spinning solution is prepared. The moisture-permeable layer spinning solution is subjected to electrospinning using the spinning liquid at a spinning voltage of 12 kV, and the spinning environment temperature is 25 °C to obtain a primary moisture-permeable layer fiber membrane; The number-average molecular weight of the polyethylene glycol is 5,000; The mass ratio of the polyurethane aqueous solution to the polyethylene glycol aqueous solution in the moisture-permeable layer spinning solution is 10:1.5.

[0017] C. Thermal crosslinking treatment The primary moisture-permeable layer fiber membrane is subjected to thermal crosslinking treatment in a nitrogen atmosphere at a heat treatment temperature of 130 °C; the treatment time is 25 min, and after the treatment is completed, the moisture-permeable layer fiber membrane is obtained; The thickness of the moisture-permeable layer fiber membrane is 30 μm.

[0018] (3)Thermal pressing and forming Lay the moisture-permeable layer fiber membrane flatly and superimposed on the base fabric, then lay the surface layer fiber membrane flatly and superimposed on the moisture-permeable layer fiber membrane, move it into a hot press, set the hot pressing time to 30 s and the hot pressing temperature to 100 °C to obtain a waterproof and moisture-permeable fabric; The base fabric is a thin (40 g / m 2 ) nylon taffeta base fabric.

[0019] Example 2 A preparation method of a waterproof and moisture-permeable fabric It includes the following steps: (1) Prepare the surface layer fiber membrane A. Prepare the primary surface layer fiber membrane Dissolve 15 g of polyurethane and 3.5 g of polycaprolactone in a mixed solvent composed of 110 g of dimethylacetamide and dichloroethane, then add 2 g of polymethylsilsesquioxane and 0.35 g of polyvinyl formal, mix evenly, stand for 2.5 h, defoam to obtain a surface spinning solution, and perform electrospinning using the surface spinning solution at a spinning voltage of 13 kV. The spinning environment temperature is 27 °C to obtain a primary surface layer fiber membrane; The polyurethane is composed of polyether-type polyurethane and polyester-type polyurethane, and the mass ratio of polyether-type polyurethane to polyester-type polyurethane is 3:1.1; The number-average molecular weight of the polyether-type polyurethane is 1500, and the number-average molecular weight of the polyester-type polyurethane is 1500; The number-average molecular weight of the polycaprolactone is 2000; The number-average molecular weight of the polymethylsilsesquioxane is 4000; The mass ratio of dimethylacetamide to dichloroethane in the mixed solvent is 1:1.2.

[0020] B. Heat treatment Perform heat treatment on the primary surface layer fiber membrane in a nitrogen atmosphere. The heat treatment temperature is 120 °C; the treatment time is 20 min. After the treatment is completed, a surface layer fiber membrane is obtained; The thickness of the surface layer fiber membrane is 12 μm.

[0021] (2) Prepare the moisture-permeable layer fiber membrane A. Prepare the polyurethane emulsion The oligomer obtained by mixing 11 g of polybutylene glycol, 3.5 g of polycaprolactam, and 3.5 g of polycaprolactone diol was dried under vacuum at 85 °C, then 0.12 g of stannous octoate catalyst was added, 16 g of diphenylmethane - 4,4'-diisocyanate was added at 65 °C, and then the reaction was carried out at 52 °C for 3.5 h to obtain a prepolymer. 22 g of acetone solvent was added to dissolve and dilute it. At 52 °C, 4.5 g of triethylamine was added for neutralization reaction for 2.2 h, then 1.7 g of diethylaminoethanol and 85 g of water were added, and stirring and water emulsification chain extension were carried out at 900 rpm. Then the solvent was removed under vacuum to obtain a polyurethane emulsion with a solid mass fraction of 32%; The number average molecular weight of the polybutylene glycol, polycaprolactam, and polycaprolactone diol is 1500.

[0022] B. Preparation of the primary moisture permeable layer fiber membrane The polyurethane emulsion was diluted into a 17 wt% polyurethane aqueous solution, polyethylene glycol was dissolved in water to prepare a 12 wt% polyethylene glycol aqueous solution, the polyurethane aqueous solution and the polyethylene glycol aqueous solution were mixed, allowed to stand and defoamed to prepare a moisture permeable layer spinning solution. The moisture permeable layer spinning solution was electrospun using the spinning liquid at a spinning voltage of 13 kV, and the spinning environment temperature was 27 °C to obtain a primary moisture permeable layer fiber membrane; The number average molecular weight of the polyethylene glycol is 5000; The mass ratio of the polyurethane aqueous solution to the polyethylene glycol aqueous solution in the moisture permeable layer spinning solution is 10:1.7.

[0023] C. Thermal cross - linking treatment The primary moisture permeable layer fiber membrane was subjected to thermal cross - linking treatment in a nitrogen atmosphere, the heat treatment temperature was 130 °C; the treatment time was 25 min, and after the treatment was completed, a moisture permeable layer fiber membrane was obtained; The thickness of the moisture permeable layer fiber membrane is 35 μm.

[0024] (3)Hot pressing and forming The moisture permeable layer fiber membrane was evenly laid on the base fabric, and then the surface layer fiber membrane was evenly laid on the moisture permeable layer fiber membrane, and then moved to a hot press. The hot pressing time was set to 35 s and the hot pressing temperature was 105 °C to obtain a waterproof and moisture permeable fabric; The base fabric is a thin - type (40 g / m 2 ) nylon taffeta base fabric.

[0025] Example 3 A preparation method of a waterproof and moisture permeable fabric Comprising the following steps: (1)Preparation of the surface layer fiber membrane A. Preparation of the primary surface layer fiber membrane Dissolve 15 g of polyurethane and 4 g of polycaprolactone in a mixed solvent composed of 120 g of dimethylacetamide and dichloroethane. Then add 2.5 g of polymethylsilsesquioxane and 0.4 g of polyvinyl formal. After mixing evenly, let it stand for 3 h to defoam and obtain the surface layer spinning solution. Use the surface layer spinning solution for electrospinning at a spinning voltage of 15 kV, and the spinning environment temperature is 30 °C to obtain the primary surface layer fiber membrane; The polyurethane is composed of polyether-type polyurethane and polyester-type polyurethane, and the mass ratio of polyether-type polyurethane to polyester-type polyurethane is 3:1.2; The number-average molecular weight of the polyether-type polyurethane is 2000, and the number-average molecular weight of the polyester-type polyurethane is 2000; The number-average molecular weight of the polycaprolactone is 3000; The number-average molecular weight of the polymethylsilsesquioxane is 5000; The mass ratio of dimethylacetamide to dichloroethane in the mixed solvent is 1:1.5.

[0026] B. Heat treatment Heat-treat the primary surface layer fiber membrane in a nitrogen atmosphere. The heat treatment temperature is 130 °C, the treatment time is 30 min, and after the treatment is completed, the surface layer fiber membrane is obtained; The thickness of the surface layer fiber membrane is 15 μm.

[0027] (2) Prepare the moisture-permeable layer fiber membrane A. Prepare the polyurethane emulsion Vacuum dry the oligomer mixture of 12 g of polybutylene glycol, 4 g of polycaprolactam, and 4 g of polycaprolactone diol at 90 °C. Then add 0.15 g of the catalyst stannous octoate, add 16 g of diphenylmethane-4,4'-diisocyanate at 70 °C, and then react at 55 °C for 4 h to obtain a prepolymer. Add 25 g of acetone solvent to dissolve and dilute. At 55 °C, add 5 g of triethylamine to neutralize and react for 2.5 h. Then add 2 g of diethylaminoethanol and 90 g of water and stir at 1000 rpm for water emulsification and chain extension. Then evacuate the solvent under vacuum to obtain a polyurethane emulsion with a solid mass fraction of 35%; The number-average molecular weights of the polybutylene glycol, polycaprolactam, and polycaprolactone diol are all 2000.

[0028] B. Prepare the primary moisture-permeable layer fiber membrane Dilute the polyurethane emulsion into a 20 wt% polyurethane aqueous solution. Dissolve polyethylene glycol in water to prepare a 15 wt% polyethylene glycol aqueous solution. Mix the polyurethane aqueous solution and the polyethylene glycol aqueous solution, let it stand and defoam to prepare the moisture-permeable layer spinning solution. The moisture-permeable layer spinning solution is used for electrospinning at a spinning voltage of 15 kV using the spinning liquid, and the spinning environment temperature is 30 °C to obtain the primary moisture-permeable layer fiber membrane; The number-average molecular weight of the polyethylene glycol is 6,000; The mass ratio of the polyurethane aqueous solution to the polyethylene glycol aqueous solution in the spinning solution of the moisture-permeable layer is 10:2; The thickness of the moisture-permeable layer fiber membrane is 40 μm.

[0029] C. Thermal cross-linking treatment The primary moisture-permeable layer fiber membrane is subjected to thermal cross-linking treatment in a nitrogen atmosphere. The heat treatment temperature is 140 °C; the treatment time is 30 min. After the treatment is completed, the moisture-permeable layer fiber membrane is obtained.

[0030] (3) Hot pressing and forming The moisture-permeable layer fiber membrane is evenly stacked and laid on the base fabric, and then the surface layer fiber membrane is evenly stacked and laid on the moisture-permeable layer fiber membrane. It is moved to a hot press, and the hot pressing time is set to 40 s and the hot pressing temperature is 110 °C to obtain the waterproof and moisture-permeable fabric; The base fabric is a thin (40 g / m 2 ) nylon taffeta base fabric.

[0031] Comparative Example 1 Comparative Example 1 adopts the preparation method of the waterproof and moisture-permeable fabric described in Example 2. The difference is that in the preparation step of the surface layer fiber membrane, 2 g of polysiloxane is used instead of 2 g of polymethylsilsesquioxane, and the other operation steps are the same.

[0032] Comparative Example 2 Comparative Example 2 adopts the preparation method of the waterproof and moisture-permeable fabric described in Example 2. The difference is that in the step of preparing the polyurethane emulsion, 7 g of polyethylene glycol is used instead of 3.5 g of polycaprolactam and 3.5 g of polycaprolactone diol, and the other operation steps are the same.

[0033] Test Example 1 The waterproof and moisture-permeable fabrics prepared in Examples 1-3 and Comparative Examples 1-2 are respectively tested for static contact angle, hydrostatic pressure and moisture permeability; after the waterproof and moisture-permeable fabrics prepared in Examples 1-3 and Comparative Examples 1-2 are washed, the static contact angle, hydrostatic pressure and moisture permeability are tested again; Washing method: The samples are subjected to standard household washing and drying according to GB / T8629-2017 "Household washing and drying procedures for textiles during testing" (type A washing machine - 4N washing temperature 40 ± 3 °C, detergent ECE 20 g, washing 20 times, drying temperature 50 - 60 °C) to complete 20 complete washing procedures; Static contact angle test: The wetting performance of the surface of the waterproof and moisture-permeable fabric is characterized by a full-automatic microscopic droplet wettability tester. The waterproof and moisture-permeable surface is fixed on a glass slide with double-sided tape, and 3 μL of deionized water is used as the test droplet, which is measured at any five points on the sample and the average value is taken; Hydrostatic pressure test: The sample was tested according to GB / T 4744-2013 "Testing and Evaluation of Waterproof Performance of Textiles - Hydrostatic Pressure Method". Moisture permeability test: The sample was tested according to GB / T 12704.2.B-2009 "Test Method for Moisture Permeability of Textile Fabrics"; the test results are shown in Table 1.

[0034] Table 1

[0035] As can be seen from Table 1, compared with Example 2, in Comparative Example 1, polysiloxane was used instead of polymethylsilsesquioxane, and the initial static contact angle and initial hydrostatic pressure of the prepared fabric were smaller than those of Example 2. The addition of polymethylsilsesquioxane to the prepared surface fiber film can effectively reduce the surface tension of the fabric, increase the static contact angle of the fabric, make water droplets not easily adhere to the fabric, and the higher hydrophobicity makes the fabric have a higher hydrostatic pressure, resulting in excellent waterproof effect. After the fabric of Comparative Example 1 underwent 20 complete standard home washing procedures, the static contact angle decreased by 18.9°, a decrease of 14.0%, and the hydrostatic pressure decreased by 12 kPa, a decrease of 23.5%. The static contact angle of Example 2 decreased by 7.3°, a decrease of 4.6%, and the hydrostatic pressure decreased by 7 kPa, a decrease of 11.1%. The decrease amplitudes of the static contact angle and hydrostatic pressure of Comparative Example 1 were significantly greater than those of Example 2, indicating that the fabric prepared in Example 2 using polymethylsilsesquioxane has better washing resistance. Polymethylsilsesquioxane contains active hydrogen atoms, which can react with polyurethane and polycaprolactone in the spinning solution, increase the crosslinking degree of polymethylsilsesquioxane with polyurethane and polycaprolactone, and improve the stability of the prepared surface fiber film. Therefore, after 20 washing procedures, the waterproof performance of the surface fiber film still remains at a relatively high level.

[0036] Compared with Example 2, in Comparative Example 2, polyethylene glycol was used instead of polycaprolactam and polycaprolactone diol in the step of preparing the polyurethane emulsion. The moisture permeability of the waterproof and moisture-permeable fabric prepared in Comparative Example 2 was less than that of Example 2. The combination of polycaprolactam and polycaprolactone diol with polyethylene glycol constitutes the soft segment of polyurethane. This soft chain segment has a relatively high chain segment movement activity at room temperature, which can enable water vapor molecules to permeate between macromolecules, improve the water vapor diffusion ability of the moisture-permeable fiber layer, and thus improve the moisture permeability of the fabric. After 20 complete standard home washing and drying, compared with Example 2, the moisture permeability of the fabric in Comparative Example 2 decreased significantly. Polycaprolactam and polycaprolactone diol can introduce keto bonds into the soft segment of polyurethane. The bond energy of the keto bond is higher than that of the ether bond, so the soft segment of the polyurethane molecule containing the keto bond is more stable. Even after multiple washing and drying, the soft chain segment of polyurethane is not easily damaged, and the influence on moisture permeability is relatively small.

[0037] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or perform equivalent replacements for some of the technical features. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for preparing a waterproof and breathable fabric, characterized in that: The method for preparing the waterproof and breathable fabric comprises the following steps: preparing a surface fiber membrane, preparing a breathable layer fiber membrane, and hot pressing and forming; The method for preparing the surface fiber membrane comprises preparing a primary surface fiber membrane and heat treating it; The method for preparing the primary surface fiber membrane comprises dissolving polyurethane and polycaprolactone in a mixed solvent composed of dimethylacetamide and ethylene dichloride, adding polymethylsilsesquioxane and polyvinyl formal, mixing evenly, standing and defoaming to obtain a surface spinning solution, and performing electrostatic spinning using the surface spinning solution at a spinning voltage of 12-15 kV and a spinning environment temperature of 25-30° C. to obtain a primary surface fiber membrane; The method for preparing the moisture permeable layer fiber membrane comprises preparing a polyurethane emulsion, preparing a primary moisture permeable layer fiber membrane, and performing a thermal cross-linking treatment; The method for preparing the polyurethane emulsion comprises the following steps: vacuum drying a mixed oligomer of polybutylene glycol, polycaprolactam and polycaprolactone diol at 80-90° C., adding a catalyst of stannous octoate, adding diphenylmethane-4,4'-diisocyanate at 60-70° C., reacting at 50-55° C. for 3-4 hours to obtain a prepolymer, adding an acetone solvent to dissolve and dilute, adding triethylamine at 50-55° C. to neutralize and react for 2-2.5 hours, adding diethylaminoethanol and water to emulsify and extend the chain under high-speed stirring, and then vacuum extracting the solvent to obtain a polyurethane emulsion with a solid mass fraction of 30-35%.

2. The method for preparing a waterproof and breathable fabric according to claim 1, characterized in that: In the step of preparing the primary surface fiber membrane, the mass ratio of polyurethane, polycaprolactone, mixed solvent, polymethylsilsesquioxane, and polyvinyl formal in the surface spinning solution is 15:3-4:100-120:1.5-2.5:0.3-0.4; The mass ratio of dimethylacetamide to dichloroethane in the mixed solvent is 1:1-1.

5.

3. The method for preparing a waterproof and breathable fabric according to claim 1, characterized in that: The heat treatment method is to heat treat the primary surface fiber membrane in a nitrogen atmosphere at a temperature of 120-130° C. and a treatment time of 20-30 min, and obtain the surface fiber membrane after the treatment is completed.

4. The method for preparing a waterproof and breathable fabric according to claim 1, characterized in that: In the step of preparing the polyurethane emulsion, The mass ratio of diphenylmethane-4,4'-diisocyanate, polybutylene glycol, polycaprolactam and polycaprolactone diol is 16:10-12:3-4:3-4; The mass ratio of diphenylmethane-4,4'-diisocyanate to stannous octoate is 16:0.1-0.

15.

5. The method for preparing a waterproof and breathable fabric according to claim 1, characterized in that: In the step of preparing the polyurethane emulsion, The mass ratio of diphenylmethane-4,4'-diisocyanate to acetone is 16:20-25; The mass ratio of diphenylmethane-4,4'-diisocyanate to triethylamine is 16:4-5; The mass ratio of the diphenylmethane-4,4'-diisocyanate, diethylaminoethanol and water is 16:1.5-2:80-90.

6. The method for preparing a waterproof and breathable fabric according to claim 1, characterized in that: The method for preparing the primary moisture permeable layer fiber membrane comprises the following steps: diluting a polyurethane emulsion into a polyurethane aqueous solution, dissolving polyethylene glycol in water to prepare a polyethylene glycol aqueous solution, mixing the polyurethane aqueous solution and the polyethylene glycol aqueous solution, standing and defoaming the mixture to prepare a moisture permeable layer spinning solution, electrostatically spinning the moisture permeable layer spinning solution using the spinning liquid at a spinning voltage of 12-15 kV, and the spinning environment temperature being 25-30° C., to obtain a primary moisture permeable layer fiber membrane.

7. The method for preparing a waterproof and breathable fabric according to claim 6, characterized in that: In the step of preparing the primary moisture permeable layer fiber membrane, the concentration of the polyurethane aqueous solution is 15-20wt%, the concentration of the polyethylene glycol aqueous solution is 10-15wt%, and the mass ratio of the polyurethane aqueous solution to the polyethylene glycol aqueous solution in the moisture permeable layer spinning solution is 10:1.5-2.

8. The method for preparing a waterproof and breathable fabric according to claim 1, characterized in that: The heat crosslinking treatment method is to heat crosslink the primary moisture permeable layer fiber membrane in a nitrogen atmosphere at a temperature of 130-140° C. and a treatment time of 25-30 minutes, and obtain a moisture permeable layer fiber membrane after the treatment is completed.

9. The method for preparing a waterproof and breathable fabric according to claim 1, characterized in that: The preparation method of hot pressing molding is to evenly stack and lay the moisture-permeable layer fiber membrane on the base fabric, then evenly stack and lay the surface fiber membrane on the moisture-permeable layer fiber membrane, move it to a pressing machine for hot pressing molding, set the hot pressing time to 30-40s and the hot pressing temperature to 100-110°C, and obtain a waterproof and moisture-permeable fabric.

10. The method for preparing a waterproof and breathable fabric according to claim 9, characterized in that: The thickness of the surface fiber membrane is 10-15 μm; the thickness of the moisture permeable layer fiber membrane is 30-40 μm.

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