Preparation Process of Polyurethane Nanoscale Microporous Membrane for Protective Clothing

Abstract

The present invention relates to a preparation process of a polyurethane nano - microporous membrane for protective clothing, belonging to the technical field of clothing fabric preparation, and specifically includes the following steps: Extract silk fibroin and perform hydrophobic modification to obtain modified silk fibroin. Subsequently, mix and dissolve it with polyurethane in a solvent, add a pore - forming agent and breathable particles obtained by mixing modified cellulose and aerogel powder to prepare a mother liquor. Finally, use the mother liquor to make a membrane, and a polyurethane nano - microporous membrane for protective clothing can be obtained. This process significantly improves the mechanical properties of the membrane and optimizes the breathable performance by mixing modified silk fibroin and polyurethane materials and adding breathable particles obtained by mixing modified cellulose and aerogel powder. At the same time, through the acetylation treatment of silk fibroin and the modification of carboxymethyl cellulose with dopamine hydrochloride, the overall performance of the material and the stability during the preparation process are further improved.

Description

Technical Field

[0001] The present application relates to the technical field of clothing fabric preparation, and more specifically, it relates to a preparation process for a polyurethane nano - microporous membrane for protective clothing. Background Art

[0002] In the field of modern protective clothing materials, polyurethane microporous membranes are widely used due to their unique breathability and certain waterproof properties. However, the polyurethane microporous membranes prepared by existing technologies still have some deficiencies.

[0003] Firstly, traditional polyurethane microporous membranes often fail to reach the ideal level in terms of breaking strength and modulus, which limits their application in occasions with high - strength requirements. This is mainly because in traditional preparation processes, the materials used cannot fully exert their respective advantages, resulting in limited improvement in the overall performance of the membrane. For example, although some natural polymer materials have high strength and toughness, their compatibility with polyurethane materials is poor, making it difficult to form a stable structure after mixing.

[0004] Secondly, there are still bottlenecks in improving the breathability of the membrane in existing technologies. Although the traditional method of adding breathable particles can increase the number of micropores in the membrane to a certain extent, the distribution and uniformity of the micropores are often difficult to control, resulting in an insignificant improvement in breathability. In addition, the addition of breathable particles may also affect the hydrophobic properties of the membrane, greatly reducing the use effect of the protective clothing in a humid environment.

[0005] Based on the above statements, the present application provides a preparation process for a polyurethane nano - microporous membrane for protective clothing. Summary of the Invention

[0006] To solve the problems raised in the background art, the present application provides a preparation process for a polyurethane nano - microporous membrane for protective clothing. The present invention proposes a brand - new preparation process for a polyurethane nano - microporous membrane. This process, through the mixing of modified silk fibroin and polyurethane materials, and the addition of breathable particles obtained by mixing modified cellulose and aerogel powder, significantly improves the breaking strength and modulus of the membrane and optimizes the breathability. At the same time, through the acetylation treatment of silk fibroin and the modification of carboxymethyl cellulose with dopamine hydrochloride, the overall performance of the materials and the stability during the preparation process are further improved. These innovative points make the present invention have significant advantages and application prospects in the field of preparing polyurethane microporous membranes for protective clothing.

[0007] The present application provides a preparation process for a polyurethane nano - microporous membrane for protective clothing, adopting the following technical scheme:

[0008] A preparation process for a polyurethane nano - microporous membrane for protective clothing, comprising the following preparation steps:

[0009] S1. Extract silk fibroin, perform hydrophobic modification on the silk fibroin, and prepare the modified silk fibroin;

[0010] S2. Mix the modified silk fibroin obtained in step S1 with polyurethane in a solvent, stir at room temperature until dissolved, add a pore-forming agent and breathable particles to obtain a mother liquor;

[0011] S3. Use the mother liquor obtained in step S2 to make a film, and obtain a polyurethane nano-porous membrane for protective clothing;

[0012] Among them, the breathable particles are obtained by mixing modified cellulose and aerogel powder.

[0013] Further, in step S1, the modified silk fibroin is specifically prepared by the following steps:

[0014] S11. Mix urea and guanidine hydrochloride, after heat treatment, obtain a protein sol solution; then cut the silk fibers into pieces, add them to the protein sol solution, stir evenly, raise the system temperature and treat for 20 - 30 hours, then wash and filter to obtain silk fibroin;

[0015] S12. Add the silk fibroin to deionized water, raise the system temperature to 50 - 60 °C, stir, then add acetic anhydride and adjust the system pH value to 9 - 10, continue to react for 1 - 3 hours, then adjust the system pH value to neutral, and dialyze at 0 - 4 °C to obtain the modified silk fibroin.

[0016] Further, in step S1, the modified silk fibroin is specifically prepared by the following steps:

[0017] S11. Mix urea and guanidine hydrochloride in a mass ratio of 2:1, then raise the system temperature to 90 °C, heat-treat for 2 hours to obtain a protein sol solution; then cut the silk fibers into pieces, add them to the protein sol solution in a mass ratio of 1:100, stir evenly, raise the system temperature to 100 °C, treat for 24 hours, then wash with deionized water and filter to obtain silk fibroin;

[0018] S12. Add the silk fibroin to deionized water according to a mass-volume ratio of 1 g:5 - 10 mL, raise the system temperature to 50 - 60 °C, stir at a rate of 30 - 90 rpm for 10 - 15 minutes, then add acetic anhydride and use NaOH solution to adjust the system pH value to 9 - 10, continue to react for 1 - 3 hours, then use HCl solution to adjust the system pH value to neutral, and dialyze at 0 - 4 °C for 48 hours to obtain the modified silk fibroin.

[0019] Further, in the above reaction process, silk fibroin in silk fiber was extracted using a protein gel solution, and then the silk fibroin was modified using acetic anhydride as an acylating reagent. The acylating reagent undergoes a nucleophilic substitution reaction with the amino group in the protein molecule, introducing hydrophobic acetyl groups onto the protein and changing the protein structure to expose more hydrophobic groups, thereby preparing the modified silk fibroin.

[0020] Further, in step S12, the usage amount ratio of silk fibroin to acetic anhydride is 1:(0.2 - 0.3).

[0021] Further, in step S2, the mass ratio of the modified silk fibroin, polyurethane, pore-forming agent, and breathable particles is (20 - 30):100:(5 - 10):(10 - 20).

[0022] Further, the pore-forming agent is nano-zinc oxide.

[0023] Further, in step S3, the breathable particles are specifically prepared by the following steps:

[0024] S21. Add 2-morpholinoethanesulfonic acid to deionized water, adjust the pH value of the system to 5.5 - 6.7, and stir the system at room temperature until dissolved to obtain a 2-morpholinoethanesulfonic acid buffer solution; dissolve carboxymethyl cellulose, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, N-hydroxysuccinimide, and dopamine hydrochloride in the 2-morpholinoethanesulfonic acid buffer solution, and stir under room temperature and an inert gas atmosphere to obtain the modified cellulose.

[0025] S22. Add sodium alginate to deionized water, stir evenly at room temperature, add a calcium chloride solution to the system, stir for 10 - 30 minutes, then freeze-dry, and subsequently pulverize and sieve to obtain an aerogel powder; mix the aerogel powder with the modified cellulose obtained in step S21 to obtain the breathable particles.

[0026] Further, in step S3, the breathable particles are specifically prepared by the following steps:

[0027] S21. Add 0.5 - 0.8 g of 2-morpholinoethanesulfonic acid to 30 mL of deionized water, use a NaOH solution to adjust the pH value of the system to 5.5 - 6.7, and stir the system at room temperature until dissolved to obtain a 2-morpholinoethanesulfonic acid buffer solution; dissolve carboxymethyl cellulose, 0.192 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, 0.115 g of N-hydroxysuccinimide, and dopamine hydrochloride in 10 mL of the 2-morpholinoethanesulfonic acid buffer solution, and stir for 24 hours under room temperature and an inert gas atmosphere to obtain the modified cellulose.

[0028] S22. Add sodium alginate to deionized water at a mass-to-volume ratio of (1 - 3) g:100 mL, stir evenly at room temperature, add 10 - 20 mL of 3.5 wt% calcium chloride solution to the system, stir at a rate of 60 - 120 rpm for 10 - 30 minutes, then freeze-dry the system at -40 °C for 2 - 3 hours, and then crush and pass through a 100-mesh sieve to obtain aerogel powder. Mix the aerogel powder with the modified cellulose obtained in step S21 to obtain breathable particles.

[0029] Further, during the above reaction process, carboxymethyl cellulose is modified using dopamine hydrochloride. The amino group on dopamine hydrochloride reacts with the carboxyl group on carboxymethyl cellulose in the EDC / NHS system to undergo an amidation reaction, introducing amide groups and catechol groups onto carboxymethyl cellulose, and preparing modified cellulose. Mix the modified cellulose with sodium alginate aerogel powder to obtain breathable particles.

[0030] Further, in step S21, the mass ratio of carboxymethyl cellulose to dopamine hydrochloride is (5 - 10):(0.1 - 1).

[0031] Further, the mass ratio of aerogel powder to modified cellulose is 1:(0.2 - 0.4).

[0032] Further, the specific operation of using the mother liquor obtained in step S2 for film preparation is as follows:

[0033] Ultrasonically mix the mother liquor for 10 - 20 minutes, then coat it on a stainless steel substrate, cure it naturally for 10 - 30 minutes, then wash it with deionized water and dry it in vacuum.

[0034] Further, the polyurethane is a polyurethane material containing a benzene ring structure.

[0035] In summary, the present application has the following beneficial effects:

[0036] 1. In the technical solution of the present invention, modified silk fibroin is mixed with a polyurethane material for the preparation of a microporous membrane, and breathable particles obtained by mixing modified cellulose and aerogel powder are added. As a natural polymer material, silk fibroin has high strength and toughness. After being mixed with the polyurethane material, their respective advantages can be exerted, significantly improving the breaking strength and modulus of the membrane. The addition of breathable particles, especially the combination of modified cellulose and aerogel powder, can form more micropores in the membrane. These micropores help to improve the gas permeability of the membrane, enabling air or gas to more easily pass through the membrane layer, achieving the effect of hydrophobic gas permeability.

[0037] 2. In the technical solution of the present invention, the silk fibroin is acetylated, introducing hydrophobic acetyl groups onto the silk fibroin. By increasing the amount of acylating reagent used, the degree of acylation of the silk fibroin is increased, exposing more hydrophobic groups on the protein, further improving the hydrophobicity of the protein and its dissolution effect in the solvent. The polyurethane material itself has a microphase separation structure, and its hard segments and soft segments tend to spontaneously separate thermodynamically. After acylation modification, the silk fibroin has a more extended structure, which promotes the interaction and dispersion between the hard segments and soft segments of the polyurethane, thereby further stabilizing the microphase separation structure and improving the overall performance of the material.

[0038] 3. In the technical solution of the present invention, dopamine hydrochloride is used to modify carboxymethyl cellulose and then mixed with sodium alginate aerogel powder to prepare breathable particles. The modified carboxymethyl cellulose can have good dispersion stability in the polyurethane matrix through π-π interaction, and can form covalent bonds with the amino groups on the silk fibroin through Michael addition and metal ion coordination bonds with the pore-forming agent nano-zinc oxide, further promoting the uniform dispersion of each component in the system, preventing the aggregation of the pore-forming agent, and improving the uniformity of the pores in the porous membrane product. Detailed implementation manners

[0039] The following will combine the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0040] In the specific implementation manners of the present application:

[0041] Carboxymethyl cellulose: Brand is Sigma-Aldrich, product number is 1096611.

[0042] Polyurethane: Diphenylmethane diisocyanate (MDI) type polyurethane.

[0043] Nano-zinc oxide: Provided by Shandong Xingya New Materials Co., Ltd., with an average particle size of 30 - 50 nm and a particle size less than 100 nm.

[0044] Example 1

[0045] The present application provides a preparation process for a polyurethane nano-scale microporous membrane for protective clothing, adopting the following technical solution:

[0046] A preparation process for a polyurethane nano-scale microporous membrane for protective clothing specifically includes the following preparation steps:

[0047] S1. Extract silk fibroin, perform hydrophobic modification on the silk fibroin to prepare modified silk fibroin. The specific operations are as follows:

[0048] S11. Mix urea and guanidine hydrochloride in a mass ratio of 2:1, then raise the system temperature to 90 °C. After heating for 2 hours, a protein sol solution is obtained. Subsequently, cut the silk fibers into pieces and add them to the protein sol solution in a mass ratio of 1:100. After stirring evenly, raise the system temperature to 100 °C. After treatment for 24 hours, wash with deionized water and filter to obtain silk fibroin.

[0049] S12. Add silk fibroin to deionized water in a mass-to-volume ratio of 1 g:5 mL, raise the system temperature to 50 °C, stir at a rate of 30 rpm for 10 minutes, then add acetic anhydride and use NaOH solution to adjust the system pH value to 9. Continue to react for 1 hour, then use HCl solution to adjust the system pH value to neutral, and dialyze at 0 °C for 48 hours to obtain modified silk fibroin. Among them, the usage amounts of silk fibroin and acetic anhydride are 1:0.2.

[0050] S2. Mix the modified silk fibroin obtained in step S1 with polyurethane in a mass-to-volume ratio of 1 g:5 mL in a tetrahydrofuran solvent, stir at room temperature until dissolved, add a pore-forming agent and breathable particles to obtain a mother liquor. Among them, the mass ratio of the modified silk fibroin, polyurethane, pore-forming agent and breathable particles is 20:100:5:10.

[0051] The pore-forming agent used is nano zinc oxide.

[0052] The breathable particles used are specifically prepared by the following steps:

[0053] S21. Add 0.5 g of 2-(N-morpholino)ethanesulfonic acid to 30 mL of deionized water, use NaOH solution to adjust the system pH value to 5.5, and stir the system at room temperature until dissolved to obtain a 2-(N-morpholino)ethanesulfonic acid buffer solution. Dissolve 5 g of carboxymethyl cellulose, 0.192 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, 0.115 g of N-hydroxysuccinimide and 0.1 g of dopamine hydrochloride in 10 mL of the 2-(N-morpholino)ethanesulfonic acid buffer solution, and stir at room temperature and under a nitrogen atmosphere for 24 hours to obtain modified cellulose.

[0054] S22. Add sodium alginate to deionized water at a mass-to-volume ratio of 1 g:100 mL, stir evenly at room temperature, add 10 mL of 3.5 wt% calcium chloride solution to the system, stir at a rate of 60 rpm for 10 minutes, then freeze-dry the system at -40 °C for 2 hours, and then crush it and pass it through a 100-mesh sieve to obtain aerogel powder; mix the aerogel powder with the modified cellulose obtained in step S21 to obtain breathable particles; wherein, the mass ratio of the aerogel powder to the modified cellulose is 1:0.2.

[0055] S3. Use the mother liquor obtained in step S2 to prepare a film. Ultrasonically mix the mother liquor for 10 minutes, then coat it on a stainless steel substrate and cure it naturally for 10 minutes. Then wash it 3 times with deionized water and dry it under vacuum at 1 Pa and -55 °C to obtain a polyurethane nano-porous membrane for protective clothing.

[0056] Example 2

[0057] A preparation process of a polyurethane nano-porous membrane for protective clothing specifically includes the following preparation steps:

[0058] S1. Extract silk fibroin, perform hydrophobic modification on silk fibroin to prepare modified silk fibroin. The specific operation is as follows:

[0059] S11. Mix urea and guanidine hydrochloride at a mass ratio of 2:1, then raise the system temperature to 90 °C, heat-treat for 2 hours to obtain a protein sol solution; then cut the silk fibers into pieces, add them to the protein sol solution at a mass ratio of 1:100, stir evenly, then raise the system temperature to 100 °C, treat for 24 hours, wash with deionized water, and filter to obtain silk fibroin;

[0060] S12. Add silk fibroin to deionized water at a mass-to-volume ratio of 1 g:8 mL, raise the system temperature to 55 °C, stir at a rate of 60 rpm for 10 minutes, then add acetic anhydride and use a NaOH solution to adjust the system pH value to 9, continue to react for 2 hours, then use an HCl solution to adjust the system pH value to neutral, and dialyze at 0 °C for 48 hours to obtain modified silk fibroin; wherein, the usage amounts of silk fibroin and acetic anhydride are 1:0.25.

[0061] S2. Mix the modified silk fibroin obtained in step S1 with polyurethane at a mass-to-volume ratio of 1 g:5 mL in a tetrahydrofuran solvent, stir at room temperature until dissolved, add a pore-forming agent and breathable particles to obtain a mother liquor; wherein, the mass ratio of the modified silk fibroin, polyurethane, pore-forming agent and breathable particles is 25:100:7:15;

[0062] The pore-forming agent used is nano-zinc oxide;

[0063] The breathable particles used are specifically prepared by the following steps:

[0064] S21. Add 0.65 g of 2-morpholinoethanesulfonic acid to 30 mL of deionized water, adjust the pH value of the system to 6.1 using NaOH solution, and stir the system at room temperature until dissolved to obtain a 2-morpholinoethanesulfonic acid buffer solution; dissolve 8 g of carboxymethyl cellulose, 0.192 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, 0.115 g of N-hydroxysuccinimide, and 0.5 g of dopamine hydrochloride in 10 mL of the 2-morpholinoethanesulfonic acid buffer solution, and stir for 24 hours at room temperature under a nitrogen atmosphere to obtain modified cellulose.

[0065] S22. Add sodium alginate to deionized water according to a mass-volume ratio of 2 g:100 mL, stir evenly at room temperature, add 15 mL of 3.5 wt% calcium chloride solution to the system, stir at a rate of 90 rpm for 20 minutes, then freeze-dry the system at -40 °C for 2.5 hours, and then crush and pass through a 100-mesh sieve to obtain aerogel powder; mix the aerogel powder with the modified cellulose obtained in step S21 to obtain breathable particles; among them, the mass ratio of the aerogel powder to the modified cellulose is 1:0.3.

[0066] S3. Use the mother liquor obtained in step S2 to prepare a film. Ultrasonically mix the mother liquor for 15 minutes, then coat it on a stainless steel substrate, cure it naturally for 20 minutes, then wash it 3 times with deionized water, and vacuum-dry it under the conditions of 1 Pa and -55 °C to obtain a polyurethane nano-porous membrane for protective clothing.

[0067] Example 3

[0068] A preparation process of a polyurethane nano-porous membrane for protective clothing specifically includes the following preparation steps:

[0069] S1. Extract silk fibroin and perform hydrophobic modification on silk fibroin to prepare modified silk fibroin. The specific operation is as follows:

[0070] S11. Mix urea and guanidine hydrochloride in a mass ratio of 2:1, then raise the temperature of the system to 90 °C, heat-treat for 2 hours to obtain a protein sol solution; then cut the silk fiber into pieces, add it to the protein sol solution in a mass ratio of 1:100, stir evenly, then raise the temperature of the system to 100 °C, treat for 24 hours, wash with deionized water, and filter to obtain silk fibroin.

[0071] S12. Add silk fibroin to deionized water at a mass-volume ratio of 1 g:10 mL, raise the temperature of the system to 60 °C, stir at a rate of 90 rpm for 15 minutes, then add acetic anhydride and adjust the pH value of the system to 10 using NaOH solution, continue the reaction for 3 hours, then adjust the pH value of the system to neutral using HCl solution, and dialyze at 4 °C for 48 hours to obtain modified silk fibroin; among them, the usage amounts of silk fibroin and acetic anhydride are 1:0.3.

[0072] S2. Mix the modified silk fibroin obtained in step S1 with polyurethane at a mass-volume ratio of 1 g:5 mL in a tetrahydrofuran solvent, stir at room temperature until dissolved, add a pore-forming agent and breathable particles to obtain a mother liquor; among them, the mass ratio of modified silk fibroin, polyurethane, pore-forming agent and breathable particles is 30:100:10:20;

[0073] The pore-forming agent used is nano-zinc oxide;

[0074] The breathable particles used are specifically prepared by the following steps:

[0075] S21. Add 0.8 g of 2-morpholinoethanesulfonic acid to 30 mL of deionized water, adjust the pH value of the system to 6.7 using NaOH solution, and stir the system at room temperature until dissolved to obtain a 2-morpholinoethanesulfonic acid buffer solution; dissolve 10 g of carboxymethyl cellulose, 0.192 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, 0.115 g of N-hydroxysuccinimide and 1.0 g of dopamine hydrochloride in 10 mL of 2-morpholinoethanesulfonic acid buffer solution, and stir at room temperature and under a nitrogen atmosphere for 24 hours to obtain modified cellulose;

[0076] S22. Add sodium alginate to deionized water at a mass-volume ratio of 3 g:100 mL, stir evenly at room temperature, add 20 mL of 3.5 wt% calcium chloride solution to the system, stir at a rate of 120 rpm for 10 - 30 minutes, then freeze-dry the system at -40 °C for 3 hours, and then crush and pass through a 100-mesh sieve to obtain aerogel powder; mix the aerogel powder with the modified cellulose obtained in step S21 to obtain breathable particles; among them, the mass ratio of aerogel powder and modified cellulose is 1:0.4.

[0077] S3. Use the mother liquor obtained in step S2 to make a film, ultrasonically mix the mother liquor for 20 minutes, then coat it on a stainless steel substrate, cure naturally for 30 minutes, then wash it 3 times with deionized water, and dry it under vacuum at 1 Pa and -55 °C to obtain a polyurethane nano-porous membrane for protective clothing.

[0078] Comparative Example 1

[0079] The difference between this comparative example and Example 1 is that in this comparative example, silk fibroin is not modified. The specific operation is as follows:

[0080] A preparation process of a polyurethane nano - microporous membrane for protective clothing specifically includes the following preparation steps:

[0081] S1. Extract silk fibroin. The specific operation is as follows:

[0082] Mix urea and guanidine hydrochloride in a mass ratio of 2:1, then raise the system temperature to 90 °C. After heat treatment for 2 hours, a protein sol solution is obtained. Then cut the silk fiber into pieces and add it to the protein sol solution in a mass ratio of 1:100. After stirring evenly, raise the system temperature to 100 °C. After treatment for 24 hours, wash with deionized water and filter to obtain silk fibroin.

[0083] S2. Mix the silk fibroin obtained in step S1 with polyurethane in a mass - volume ratio of 1 g:5 mL in a tetrahydrofuran solvent, stir at room temperature until dissolved, and add a pore - forming agent and breathable particles to obtain a mother liquor. Among them, the mass ratio of silk fibroin, polyurethane, pore - forming agent, and breathable particles is 20:100:5:10.

[0084] The pore - forming agent used is nano - zinc oxide.

[0085] The breathable particles used are specifically prepared by the following steps:

[0086] S21. Add 0.5 g of 2 - morpholinoethanesulfonic acid to 30 mL of deionized water, adjust the pH value of the system to 5.5 with NaOH solution, and stir the system at room temperature until dissolved to obtain a 2 - morpholinoethanesulfonic acid buffer solution. Dissolve 5 g of carboxymethyl cellulose, 0.192 g of 1 - (3 - dimethylaminopropyl) - 3 - ethylcarbodiimide hydrochloride, 0.115 g of N - hydroxysuccinimide, and 0.1 g of dopamine hydrochloride in 10 mL of 2 - morpholinoethanesulfonic acid buffer solution, and stir for 24 hours at room temperature and in a nitrogen atmosphere to obtain modified cellulose.

[0087] S22. Add sodium alginate to deionized water in a mass - volume ratio of 1 g:100 mL, stir evenly at room temperature, add 10 mL of 3.5 wt% calcium chloride solution to the system, stir at a rate of 60 rpm for 10 minutes, then freeze - dry the system at - 40 °C for 2 hours, and then crush and pass through a 100 - mesh sieve to obtain aerogel powder. Mix the aerogel powder with the modified cellulose obtained in step S21 to obtain breathable particles. Among them, the mass ratio of aerogel powder and modified cellulose is 1:0.2.

[0088] S3. Use the mother liquor obtained in step S2 to prepare a film. Ultrasonically mix the mother liquor for 10 minutes, then coat it on a stainless steel substrate and allow it to cure naturally for 10 minutes. Then wash it 3 times with deionized water and dry it under vacuum at 1 Pa and -55 °C to obtain a polyurethane nano-scale microporous film for protective clothing.

[0089] Comparative Example 2

[0090] The difference between this comparative example and Example 1 is that in this comparative example, the breathable particles are obtained by mixing carboxymethyl cellulose and aerogel powder. The specific operation is as follows:

[0091] A preparation process for a polyurethane nano-scale microporous film for protective clothing specifically includes the following preparation steps:

[0092] S1. Extract silk fibroin, perform hydrophobic modification on the silk fibroin to prepare modified silk fibroin. The specific operation is as follows:

[0093] S11. Mix urea and guanidine hydrochloride in a mass ratio of 2:1, then raise the system temperature to 90 °C and heat-treat for 2 hours to obtain a protein sol solution. Then cut the silk fiber into pieces and add it to the protein sol solution in a mass ratio of 1:100. After stirring evenly, raise the system temperature to 100 °C and treat for 24 hours, then wash with deionized water and filter to obtain silk fibroin.

[0094] S12. Add the silk fibroin to deionized water in a mass-to-volume ratio of 1 g:5 mL, raise the system temperature to 50 °C, stir at a rate of 30 rpm for 10 minutes, then add acetic anhydride and use a NaOH solution to adjust the system pH value to 9. Continue to react for 1 hour, then use an HCl solution to adjust the system pH value to neutral and dialyze at 0 °C for 48 hours to obtain modified silk fibroin. Among them, the usage amounts of silk fibroin and acetic anhydride are 1:0.2.

[0095] S2. Mix the modified silk fibroin obtained in step S1 with polyurethane in a mass-to-volume ratio of 1 g:5 mL in a tetrahydrofuran solvent, stir at room temperature until dissolved, add a pore-forming agent and breathable particles to obtain a mother liquor. Among them, the mass ratio of modified silk fibroin, polyurethane, pore-forming agent, and breathable particles is 20:100:5:10.

[0096] The pore-forming agent used is nano-zinc oxide.

[0097] The breathable particles used are specifically prepared by the following steps:

[0098] S21. Add sodium alginate to deionized water at a mass-volume ratio of 1 g:100 mL, stir evenly at room temperature, add 10 mL of 3.5 wt% calcium chloride solution to the system, stir at a rate of 60 rpm for 10 minutes, then freeze-dry the system at -40 °C for 2 hours, and then crush it and pass through a 100-mesh sieve to obtain aerogel powder; mix the aerogel powder with carboxymethyl cellulose to obtain breathable particles; wherein, the mass ratio of the aerogel powder to carboxymethyl cellulose is 1:0.2.

[0099] S3. Use the mother liquor obtained in step S2 for film preparation. Ultrasonically mix the mother liquor for 10 minutes, then coat it on a stainless steel substrate and cure it naturally for 10 minutes. Then wash it 3 times with deionized water and vacuum dry it under the conditions of 1 Pa and -55 °C to obtain a polyurethane nano-porous membrane for protective clothing.

[0100] Comparative Example 3

[0101] The difference between this comparative example and Example 1 is that the breathable particles in this comparative example are aerogel powder, and the specific operation is as follows:

[0102] A preparation process of a polyurethane nano-porous membrane for protective clothing specifically includes the following preparation steps:

[0103] S1. Extract silk fibroin, perform hydrophobic modification on silk fibroin to prepare modified silk fibroin, and the specific operation is as follows:

[0104] S11. Mix urea and guanidine hydrochloride in a mass ratio of 2:1, then raise the temperature of the system to 90 °C, heat-treat for 2 hours to obtain a protein sol solution; then cut the silk fiber into pieces, add it to the protein sol solution at a mass ratio of 1:100, stir evenly, then raise the temperature of the system to 100 °C, treat for 24 hours, wash with deionized water, and filter to obtain silk fibroin;

[0105] S12. Add silk fibroin to deionized water at a mass-volume ratio of 1 g:5 mL, raise the temperature of the system to 50 °C, stir at a rate of 30 rpm for 10 minutes, then add acetic anhydride and use NaOH solution to adjust the pH value of the system to 9, continue to react for 1 hour, then use HCl solution to adjust the pH value of the system to neutral, and dialyze at 0 °C for 48 hours to obtain modified silk fibroin; wherein, the usage amounts of silk fibroin and acetic anhydride are 1:0.2.

[0106] S2. Mix the modified silk fibroin obtained in step S1 with polyurethane in a mass-volume ratio of 1 g:5 mL in a tetrahydrofuran solvent, stir at room temperature until dissolved, add a pore-forming agent and breathable particles to obtain a mother liquor; wherein, the mass ratio of the modified silk fibroin, polyurethane, pore-forming agent and breathable particles is 20:100:5:10;

[0107] The pore-forming agent used is nano-zinc oxide;

[0108] The breathable particles used are specifically prepared by the following steps:

[0109] Sodium alginate is added to deionized water according to a mass-volume ratio of 1 g:100 mL, stirred evenly at room temperature, 10 mL of 3.5 wt% calcium chloride solution is added to the system, after stirring at a rate of 60 rpm for 10 minutes, the system is freeze-dried at -40 °C for 2 hours, and then crushed and sieved through a 100-mesh sieve to obtain the breathable particles.

[0110] S3. Use the mother liquor obtained in step S2 to make a film. The mother liquor is ultrasonically mixed for 10 minutes, then coated on a stainless steel substrate, naturally cured for 10 minutes, then washed 3 times with deionized water, and vacuum dried at 1 Pa and -55 °C to obtain a polyurethane nano-scale microporous membrane for protective clothing.

[0111] Comparative Example 4

[0112] The difference between this comparative example and Example 1 is that in this comparative example, a small amount of acetic anhydride is used to modify silk fibroin, and the specific operation is as follows:

[0113] A preparation process of a polyurethane nano-scale microporous membrane for protective clothing specifically includes the following preparation steps:

[0114] S1. Extract silk fibroin, perform hydrophobic modification on silk fibroin to prepare modified silk fibroin. Specifically, the difference is that in step S12, the usage amounts of silk fibroin and acetic anhydride are 1:0.1.

[0115] Comparative Example 5

[0116] The difference between this comparative example and Example 1 is that in this comparative example, silk fibroin is not used to enhance the microporous membrane product, and the specific operation is as follows:

[0117] A preparation process of a polyurethane nano-scale microporous membrane for protective clothing specifically includes the following preparation steps:

[0118] S1. Mix polyurethane according to a mass-volume ratio of 1 g:5 mL in a tetrahydrofuran solvent, stir at room temperature until dissolved, add a pore-forming agent and breathable particles to obtain a mother liquor; among them, the mass ratio of polyurethane, pore-forming agent and breathable particles is 120:5:10;

[0119] The pore-forming agent used is nano-zinc oxide;

[0120] The breathable particles used are specifically prepared by the following steps:

[0121] 1. Add 0.5 g of 2-morpholinoethanesulfonic acid to 30 mL of deionized water, adjust the pH value of the system to 5.5 using NaOH solution, and stir the system at room temperature until dissolved to obtain 2-morpholinoethanesulfonic acid buffer solution; dissolve 5 g of carboxymethyl cellulose, 0.192 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, 0.115 g of N-hydroxysuccinimide, and 0.1 g of dopamine hydrochloride in 10 mL of 2-morpholinoethanesulfonic acid buffer solution, and stir for 24 hours at room temperature and under a nitrogen atmosphere to obtain modified cellulose;

[0122] 2. Add sodium alginate to deionized water according to the mass-volume ratio of 1 g:100 mL, stir evenly at room temperature, add 10 mL of 3.5 wt% calcium chloride solution to the system, stir at a rate of 60 rpm for 10 minutes, then freeze-dry the system at -40 °C for 2 hours, and then crush it and pass through a 100-mesh sieve to obtain aerogel powder; mix the aerogel powder with the modified cellulose obtained in step S21 to obtain breathable particles; wherein, the mass ratio of the aerogel powder to the modified cellulose is 1:0.2.

[0123] S2. Use the mother liquor obtained in step S1 to prepare a film. Ultrasonically mix the mother liquor for 10 minutes, then coat it on a stainless steel substrate, cure it naturally for 10 minutes, then wash it 3 times with deionized water, and dry it under vacuum at 1 Pa and -55 °C to obtain a polyurethane nano-microporous membrane for protective clothing.

[0124] Performance Test

[0125] Make the nano-microporous membranes prepared in Examples 1-3 and Comparative Examples 1-5 of this application into samples with a specification of 20*20*0.2 cm. Now perform performance tests on the microporous membrane samples prepared in different groups. Before the test, adjust the test state of the samples. The pre-conditioning, conditioning, and test atmosphere should be carried out within the standard atmosphere and tolerance range specified in GB / T 6529. The state adjustment time is not less than 4 h, and the test is carried out under this condition.

[0126] Tensile strength at break, elongation at break: Conduct the test according to the provisions of GB / T 3923.1, calculate the average value of the tensile strength at break of the effective specimens, and the result is accurate to 0.1 N; calculate the average values of the elongation at break in the transverse and longitudinal directions of the effective specimens respectively, and the result is accurate to 0.5%.

[0127] Waterproof performance: Conduct the test according to the provisions of GB / T 4744. The nano-microporous membrane needs to use a 60-mesh nylon mesh to support the specimen. The nylon mesh is a square mesh with a size of 20 cm × 20 cm, and the mesh size is about 0.3 mm. It can simulate the role of the adhesive layer to prevent the specimen from being torn or stretched by water.

[0128] Air permeability: The test was carried out in accordance with the provisions of GB / T 5453. The pressure drop under the test conditions was 200 Pa, and the result was retained to 0.01 mm / s.

[0129] Water vapor transmission rate: Referring to the content of GB / T 12704.1-2009, 3.1, it is the mass of water vapor vertically passing through a unit area of the specimen within a specified time under the condition of maintaining the specified temperature and humidity on both sides of the specimen.

[0130] The specific performance test results are shown in Table 1 below.

[0131]

[0132] It can be seen from the results shown in Table 1 above that the comprehensive performance of the nanoscale microporous membranes prepared in Examples 1-3 of this application is significantly better than that of the products prepared in Comparative Examples 1-5. That is, within the scope of the technical solutions defined in this application, the comprehensive performance of the prepared nanoscale microporous membranes is excellent.

[0133] It can be seen from the results of Comparative Example 1, Comparative Example 4 and Comparative Example 5 that after acylating silk fibroin and using it to enhance the nanoscale microporous membrane material, the mechanical properties and air permeability effect of the membrane material can be improved. And after the silk fibroin is modified with a high degree of acylation, the hydrophilic property of the protein is reduced and the hydrophobic property of the membrane material is improved.

[0134] It can be seen from the results of Comparative Examples 2 and 3 that the carboxymethyl cellulose material also shows an enhancing effect on the mechanical properties of the prepared membrane material. And after being modified with dopamine hydrochloride, the dispersion uniformity of the pore-forming agent is improved, and the uniformity of the pores on the membrane material is improved, thereby improving the air permeability effect.

[0135] In the description of the specification, the description referring to terms such as "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0136] The above content is only an example and explanation of the present invention. Those skilled in the art of this technology can make various modifications or supplements to the described specific embodiments or use similar methods to replace them. As long as they do not deviate from the invention or exceed the scope defined by the claims of this patent, they should fall within the protection scope of the present invention.

Claims

1. A preparation process of a polyurethane nano-scale microporous membrane for protective clothing, characterized in that, It includes the following preparation steps: S1. Extract silk fibroin, perform hydrophobic modification on the silk fibroin to obtain modified silk fibroin. The specific operation is as follows: S11. Mix urea and guanidine hydrochloride, and after heat treatment, obtain a protein sol solution; then cut the silk fibers into pieces, add them to the protein sol solution, stir evenly, raise the temperature of the system and treat for 20 - 30 hours, then wash and filter to obtain silk fibroin; S12. Add the silk fibroin to deionized water, raise the temperature of the system to 50 - 60 °C, stir, then add acetic anhydride and adjust the pH value of the system to 9 - 10, continue to react for 1 - 3 hours, then adjust the pH value of the system to neutral, and dialyze at 0 - 4 °C to obtain modified silk fibroin; S2. Mix the modified silk fibroin obtained in step S1 with polyurethane in a solvent, stir at room temperature until dissolved, add a pore-forming agent and breathable particles to obtain a mother liquor; among them, the breathable particles are specifically prepared by the following steps: S21. Add 2 - morpholinoethanesulfonic acid to deionized water, adjust the pH value of the system to 5.5 - 6.7, and stir the system at room temperature until dissolved to obtain a 2 - morpholinoethanesulfonic acid buffer solution; dissolve carboxymethyl cellulose, 1 - (3 - dimethylaminopropyl) - 3 - ethylcarbodiimide hydrochloride, N - hydroxysuccinimide and dopamine hydrochloride in the 2 - morpholinoethanesulfonic acid buffer solution, and stir in a room temperature and inert gas atmosphere to obtain modified cellulose; S22. Add sodium alginate to deionized water, stir evenly at room temperature, add a calcium chloride solution to the system, stir for 10 - 30 minutes, then freeze - dry, and then crush and sieve to obtain aerogel powder; mix the aerogel powder with the modified cellulose obtained in step S21 to obtain breathable particles; S3. Use the mother liquor obtained in step S2 for film - making to obtain a polyurethane nano - microporous membrane for protective clothing.

2. The preparation process of the polyurethane nano-scale microporous membrane for protective clothing according to claim 1, characterized in that, In step S12, the usage amounts of silk fibroin and acetic anhydride are 1:(0.2 - 0.3).

3. The preparation process of the polyurethane nano-scale microporous membrane for protective clothing according to claim 1, characterized in that In step S2, the mass ratio of the modified silk fibroin, polyurethane, pore - forming agent and breathable particles is (20 - 30):100:(5 - 10):(10 - 20).

4. The preparation process of the polyurethane nano - microporous membrane for protective clothing according to claim 1, characterized in that, The pore - forming agent is nano - zinc oxide.

5. The preparation process of the polyurethane nano-scale microporous membrane for protective clothing according to claim 1, characterized in that, In step S21, the mass ratio of carboxymethyl cellulose to dopamine hydrochloride is (5 - 10):(0.1 - 1).

6. The preparation process of the polyurethane nano-scale microporous membrane for protective clothing according to claim 1, characterized in that, In step S22, the mass ratio of the aerogel powder and the modified cellulose is 1:(0.2 - 0.4).

7. The preparation process of the polyurethane nano-scale microporous membrane for protective clothing according to claim 1, characterized in that, The specific operation of using the mother liquor obtained in step S2 for film - making is as follows: Ultrasonically mix the mother liquor for 10 - 20 minutes, then coat it on a substrate, naturally cure for 10 - 30 minutes, then wash with deionized water and vacuum dry.

8. The preparation process of the polyurethane nano-microporous membrane for protective clothing according to claim 1, characterized in that, The polyurethane is a polyurethane material containing a benzene ring structure.

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