Preparation method of asymmetric microfiber leather substrate based on MOF enhanced performance

Abstract

The present invention relates to a preparation method of an asymmetric ultra-fine leather substrate based on MOF enhanced performance, the method comprising the following steps: the first step: sulfuric acid modification of non-woven fabric, sulfuric acid solution realizes asymmetric modification of non-woven fabric by gravity; the second step: aluminum chloride hexahydrate, 3,5-pyrazole dicarboxylic acid are added to deionized water and stirred until dissolved, and the non-woven fabric asymmetrically modified in the first step is placed in a configuration solution, and a quantitative sodium hydroxide solution is added dropwise to the solution; the third step: the solution is sealed and reacted at 90-100°C for 18-36h; the non-woven fabric after the reaction is removed and washed with deionized water and methanol for 1-5 times, respectively, after ultrasonic 1-4h, dried in a vacuum oven to obtain an asymmetric ultra-fine leather substrate. The main material of the ultra-fine leather substrate is PET / PA6 hollow orange segment type two-component spunbond spunlace ultra-fine fiber non-woven fabric, which has the characteristics of high strength, lightness, green and environmental protection.

Description

Technical Field

[0001] The invention relates to the technical field of ultrafine fiber synthetic leather, in particular to a method for preparing an asymmetric ultrafine fiber leather substrate based on MOF enhanced performance. Background Art

[0002] Due to the limited natural leather resources, the research and development of high-property synthetic leather has become one of the focuses of the global leather industry. Microfiber leather is a composite material composed of ultrafine fiber nonwoven fabric (substrate) and elastic resin. From its origin to development, it has always imitated natural leather. As a product of structural bionics, microfiber leather has achieved the transformation from "imitation" to "simulation" of natural leather through the application and modification of ultrafine fibers (imitation of collagen fiber diameter in natural leather), nonwoven materials (imitation of three-dimensional network structure of natural leather) and polyurethane resin (imitation release structure). It is a new generation of high-end synthetic leather with the closest structure and performance to natural leather in the world. It has been applied to clothing, apparel, shoes and bags, sofas, car interiors and other fields. However, compared with natural leather, microfiber leather currently generally has the defect of poor hygienic performance, especially moisture absorption and moisture permeability, which leads to the inability of human sweat to be discharged in time, thereby affecting the wearing comfort of clothing, seriously limiting its wide application in the field of clothing, and restricting the development of the synthetic leather industry. Therefore, how to prepare microfiber leather with high water absorption and high moisture permeability has become an issue that must be considered in the development of the leather industry and has attracted widespread attention from countries around the world.

[0003] Based on the in-depth study of the microstructure of natural leather and the analysis of the moisture absorption and permeability mechanism of microfiber leather, the current method to improve the moisture absorption and permeability of microfiber leather mainly starts from imitating the micro-nano size, surface activity and asymmetric structure of collagen fibers in natural leather, and carries out fiber modification and structural design of the microfiber leather substrate.

[0004] Existing ultrafine fiber preparation technologies include composite spinning (island type and split type), melt blowing, flash evaporation and electrospinning. Among them, the island type composite spinning method, as a technology that can prepare ultrafine fiber nonwoven materials at high speed and high efficiency, has received widespread attention from the industry and has become the main way to produce ultrafine fibers for synthetic leather. However, the moisture absorption and moisture permeability of PET ultrafine fibers and PA6 ultrafine leather substrates prepared by this method are poor, and there is serious pollution of solvents such as alkali solution and toluene during the reduction process. Increasing the number of active groups on the surface of ultrafine fibers plays a key role in improving the moisture permeability of ultrafine fiber synthetic leather substrates, but there is still a certain gap compared with natural leather. Compared with the island type composite spinning method, the two-component spunbond spunlace technology uses physical extrusion and shearing to break the interface connection between components, thereby realizing the green and efficient production of high-strength filament ultrafine fiber nonwoven materials, and has a broad industrial application prospect. Ma Xingyuan and others from Shaanxi University of Science and Technology analyzed in detail the microstructure and properties of PET / PA6 hollow orange-peel bicomponent spunbond spunlace microfiber nonwoven fabrics, and verified the feasibility of using it as a microfiber leather substrate. Qian Xiaoming and others from Tianjin University of Technology conducted a relatively systematic study on the use of PET / PA6 hollow orange-peel bicomponent spunbond spunlace microfiber nonwoven fabrics to prepare microfiber leather. Starting from the micro-nano size of ultrafine fibers, a series of polyacrylonitrile (PAN) nanofibers with diameters (200nm, 450nm and 900nm) were prepared by electrospinning. After blending, combing and spunlace with hollow orange-peel composite fibers, a highly simulated micro / nano fiber composite nonwoven leather substrate was obtained, and its water absorption and moisture permeability were increased by 768.99% and 28.20% respectively. Starting from the micro-nano size and surface activity of ultrafine fibers, the electrospinning method was used to successfully spin finer, highly hydrophilic thermoplastic polyurethane (TPU) / sulfonated polysulfone (SPSf) nanofibers (average diameter of 120nm). The contact angle of the prepared micro / nano fiber composite nonwoven fabric decreased from 90.40° to 67.07°, and the water absorption and moisture permeability increased by 26.25% and 55.19%, respectively. Starting from the asymmetric structure of ultrafine fiber nonwoven fabrics, a series of gradient structured two-component spunbond spunlace ultrafine fiber nonwoven fabrics were prepared by one-step and three-step methods. The construction of the gradient structure increased the moisture permeability of the nonwoven leather substrate from 3296.11g / (m 2 ·24h) increased to 4243.82g / (m 2 ·24h).

[0005] It can be seen that the existing fiber modification and structural design can effectively improve the moisture absorption and moisture permeability of microfiber leather substrates, but the current level of technology cannot meet its application needs in the field of clothing. Therefore, in order to fundamentally solve the problem of poor moisture absorption and moisture permeability of microfiber leather substrates, it has become an inevitable trend to explore a new material or new method to synergistically enhance the moisture absorption and moisture permeability of microfiber leather through multiple mechanisms. Summary of the invention

[0006] In order to solve the above technical problems, the present invention proposes a method for preparing an asymmetric microfiber leather substrate based on MOF enhanced performance. The technical problem to be solved by the present invention is achieved by the following technical solutions:

[0007] A method for preparing an asymmetric microfiber leather substrate based on MOF enhanced performance, the method comprising the following steps:

[0008] The first step: sulfuric acid modification of the nonwoven fabric, the sulfuric acid solution is evenly sprayed on the front of the PET / PA6 hollow orange-shaped bicomponent spunbond spunlace microfiber nonwoven fabric, and dried naturally at room temperature and pressure. The sulfuric acid solution achieves asymmetric modification of the nonwoven fabric through gravity;

[0009] Step 2: adding aluminum chloride hexahydrate and 3,5-pyrazoledicarboxylic acid to deionized water and stirring until dissolved, placing the asymmetrically modified nonwoven fabric in the first step into the prepared solution, and adding a quantitative sodium hydroxide solution dropwise into the solution;

[0010] Step 3: seal the solution and react it at 90-100°C for 18-36h; remove the non-woven fabric after the reaction and wash it with deionized water and methanol for 1-5 times respectively, ultrasonicate it for 1-4h, and dry it in a vacuum oven to obtain an asymmetric microfiber leather substrate.

[0011] Repeat the first step 0-3 times before proceeding to the second step;

[0012] In the first step, the concentration of the sulfuric acid solution is 5-25%, and the content of each spraying is 3-8g.

[0013] In the second step, the concentration of aluminum chloride hexahydrate is 0.8-2.0 wt %, and the concentration of 3,5-pyrazoledicarboxylic acid is 0.6-1.7 wt %.

[0014] The sodium hydroxide solution was prepared by mixing 2.6 g of sodium hydroxide with 30 ml of deionized water.

[0015] The beneficial effects of the present invention are:

[0016] 1. In order to solve the problem of poor moisture absorption and permeability of microfiber leather substrate, the PET / PA6 hollow orange-peel type two-component spunbond spunlace microfiber nonwoven fabric was hydrolyzed and modified by multi-stage spraying of sulfuric acid, so that more hydrophilic groups (-COOH and -NH2) were exposed on the surface of the microfibers while achieving a gradient distribution of the degree of modification; then, the MOF with water adsorption function was loaded onto the nonwoven fabric through the in-situ growth method to achieve in-situ asymmetric growth of MOF; finally, a systematic regulation theory and new technology were formed that can effectively improve the moisture absorption and permeability of microfiber leather substrate, laying the foundation for the widespread application of microfiber leather in the field of clothing.

[0017] 2. The asymmetric structure design of PET / PA6 hollow orange-peel bicomponent spunbond spunlace microfiber nonwoven fabric can increase the nonwoven fabric's ability to directional transmit water molecules, effectively improving the moisture absorption and moisture permeability of the microfiber leather substrate.

[0018] 3. The sulfuric acid modification of PET / PA6 hollow orange-peel bicomponent spunbond spunlace microfiber nonwoven fabric can improve the hydrophilicity and air permeability and moisture permeability of the microfiber leather substrate.

[0019] 4. The highly water-absorbent MOF nanocrystals are loaded onto the sulfuric acid-modified PET / PA6 hollow orange-peel-shaped two-component spunbond spunlace microfiber nonwoven fabric through an in-situ growth method, which can give the microfiber leather substrate excellent hydrophilicity, liquid penetration performance and water vapor adsorption and desorption ability, and can effectively improve the mechanical properties.

[0020] 5. The main material of the microfiber leather substrate is PET / PA6 hollow orange-peel type two-component spunbond spunlace microfiber non-woven fabric, which has the characteristics of high strength, lightness, thinness, greenness and environmental protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0022] Figure 1 The experimental results of the complete absorption time of water droplets in the embodiments of the present invention are as follows;

[0023] Figure 2 The SEM images of the sulfuric acid-modified microfiber leather substrate under different sulfuric acid concentrations of the present invention;

[0024] Figure 3 The SEM images of the MOF microfiber leather substrate loaded with different sulfuric acid concentrations of the present invention;

[0025] Figure 4 This is an infrared spectrum of the MOF-loaded microfiber leather substrate of the present invention;

[0026] Figure 5 This is the EDS graph of the MOF-loaded microfiber leather substrate of the present invention;

[0027] Figure 6 is the liquid penetration time of the microfiber leather substrate of the present invention;

[0028] Figure 7 It is the dynamic adsorption-desorption curve of the microfiber leather substrate of the present invention. DETAILED DESCRIPTION

[0029] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be explained more clearly and completely below in conjunction with the drawings in the embodiments. Of course, the described embodiments are only a part of the present invention but not all of it. Based on this embodiment, other embodiments obtained by those skilled in the art without creative labor are all within the protection scope of the present invention.

[0030] like Figures 1 to 7 As shown, a method for preparing an asymmetric microfiber leather substrate based on MOF enhanced performance comprises the following steps:

[0031] The first step: sulfuric acid modification of the nonwoven fabric, the sulfuric acid solution is evenly sprayed on the front of the PET / PA6 hollow orange-shaped bicomponent spunbond spunlace microfiber nonwoven fabric, and dried naturally at room temperature and pressure. The sulfuric acid solution achieves asymmetric modification of the nonwoven fabric through gravity;

[0032] Step 2: adding aluminum chloride hexahydrate and 3,5-pyrazoledicarboxylic acid to deionized water and stirring until dissolved, placing the asymmetrically modified nonwoven fabric in the first step into the prepared solution, and adding a quantitative sodium hydroxide solution dropwise into the solution;

[0033] Step 3: Seal the solution and react it at 90-100°C for 18-36h; remove the nonwoven fabric after the reaction and wash it with deionized water and methanol for 1-5 times respectively, ultrasonicate it for 1-4h, and dry it in a vacuum oven to obtain an asymmetric microfiber leather substrate. The MOF in situ growth of nonwoven fabric is achieved through the second and third steps.

[0034] Before proceeding to the second step, the first step needs to be repeated 0-3 times, and the number of repetitions is selected according to the degree of asymmetric modification;

[0035] In the first step, the concentration of sulfuric acid solution is 5-25%, and the content of each spraying is 3-8g; if the amount of sulfuric acid sprayed each time is less than 3g, the modification effect is not good; if the content exceeds 8g, it will penetrate the nonwoven material and cannot form an asymmetric modification.

[0036] In the second step, the concentration of aluminum chloride hexahydrate is 0.8-2.0wt%, and the concentration of 3,5-pyrazoledicarboxylic acid is 0.6-1.7wt%; within this range, the in-situ growth effect of MOF is better.

[0037] The sodium hydroxide solution was prepared by mixing 2.6 g of sodium hydroxide with 30 ml of deionized water.

[0038] According to the above method steps, the following embodiments are obtained:

[0039] Example 1: First, take 720mL of deionized water, 10.4g of aluminum chloride hexahydrate (AlCl3·6H2O, metal ion), and 7.5g of 3,5-pyrazoledicarboxylic acid (H3PDC·H2O, organic ligand), stir until completely dissolved, and put the untreated non-woven fabric into the prepared solution. Then, dissolve 2.6g of sodium hydroxide (NaOH) in 30mL of deionized water, add dropwise to the above mixture, seal, and react at 100°C for 24h. Finally, wash the product with deionized water and methanol 3 times, ultrasonicate for 2h, and dry it in a vacuum oven to obtain an asymmetric microfiber leather substrate.

[0040] Example 2: First, 5 wt% sulphuric acid (H2SO4) solution was evenly sprayed onto 0.06 m 2 The front side of the PET / PA6 hollow orange-shaped two-component spunbond spunlace microfiber nonwoven fabric is naturally dried at room temperature and pressure. The sulfuric acid solution achieves asymmetric modification of the nonwoven fabric due to gravity. Then take 720mL of deionized water, 10.4g of aluminum chloride hexahydrate (AlCl3·6H2O, metal ion), and 7.5g of 3,5-pyrazoledicarboxylic acid (H3PDC·H2O, organic ligand), stir until completely dissolved, and put the sulfuric acid-modified nonwoven fabric into the prepared solution. Finally, 2.6g of sodium hydroxide (NaOH) is dissolved in 30mL of deionized water, added dropwise to the above mixture, sealed, reacted at 100°C for 24h, and the product was washed 3 times with deionized water and methanol respectively. After ultrasonication for 2h, it was dried in a vacuum oven to obtain an asymmetric microfiber leather substrate.

[0041] Example 3: First, 10wt%, 5g sulfuric acid (H2SO4) solution was evenly sprayed onto 0.06m 2 The front side of the PET / PA6 hollow orange-shaped two-component spunbond spunlace microfiber nonwoven fabric is naturally dried at room temperature and pressure. The sulfuric acid solution realizes asymmetric modification of the nonwoven fabric due to gravity. Then take 720mL of deionized water, 10.4g of aluminum chloride hexahydrate (AlCl3·6H2O, metal ion), and 7.5g of 3,5-pyrazoledicarboxylic acid (H3PDC·H2O, organic ligand), stir until completely dissolved, and put the sulfuric acid-modified nonwoven fabric into the prepared solution. Finally, 2.6g of sodium hydroxide (NaOH) was dissolved in 30mL of deionized water, added dropwise to the above mixture, sealed, and reacted at 100°C for 24h. The product was washed 3 times with deionized water and methanol respectively, ultrasonicated for 2h, and dried in a vacuum oven to obtain an asymmetric microfiber leather substrate. ;

[0042] Example 4: First, 15wt%, 5g sulfuric acid (H2SO4) solution was evenly sprayed onto 0.06m 2 The front side of the PET / PA6 hollow orange-shaped two-component spunbond spunlace microfiber nonwoven fabric is naturally dried at room temperature and pressure. The sulfuric acid solution realizes asymmetric modification of the nonwoven fabric due to gravity. Then take 720mL of deionized water, 10.4g of aluminum chloride hexahydrate (AlCl3·6H2O, metal ion), and 7.5g of 3,5-pyrazoledicarboxylic acid (H3PDC·H2O, organic ligand), stir until completely dissolved, and put the sulfuric acid-modified nonwoven fabric into the prepared solution. Finally, 2.6g of sodium hydroxide (NaOH) was dissolved in 30mL of deionized water, added dropwise to the above mixture, sealed, and reacted at 100°C for 24h. The product was washed 3 times with deionized water and methanol respectively, ultrasonicated for 2h, and dried in a vacuum oven to obtain an asymmetric microfiber leather substrate. ;

[0043] Example 5: First, 20wt%, 5g sulfuric acid (H2SO4) solution was evenly sprayed onto 0.06m 2 The front side of the PET / PA6 hollow orange-shaped two-component spunbond spunlace microfiber nonwoven fabric is naturally dried at room temperature and pressure. The sulfuric acid solution achieves asymmetric modification of the nonwoven fabric due to gravity. Then take 720mL of deionized water, 10.4g of aluminum chloride hexahydrate (AlCl3·6H2O, metal ion), and 7.5g of 3,5-pyrazoledicarboxylic acid (H3PDC·H2O, organic ligand), stir until completely dissolved, and put the sulfuric acid-modified nonwoven fabric into the prepared solution. Finally, 2.6g of sodium hydroxide (NaOH) is dissolved in 30mL of deionized water, added dropwise to the above mixture, sealed, reacted at 100°C for 24h, and the product was washed 3 times with deionized water and methanol respectively. After ultrasonication for 2h, it was dried in a vacuum oven to obtain an asymmetric microfiber leather substrate.

[0044] like Figure 1 Shown are the test results of the water droplet complete absorption time of 5 examples and unmodified nonwoven fabrics.

[0045] like Figure 2 As shown, it is the SEM image of the sulfuric acid modified microfiber leather substrate, wherein the sulfuric acid concentration is 0%, 5%, 10%, 15%, and 20% from ae to ae.

[0046] like Figure 3 The following are SEM images of MOF-loaded microfiber leather substrates. a) Untreated with sulfuric acid; b) Loaded with sulfuric acid at 5% concentration; c) Loaded with sulfuric acid at 10% concentration; d) Loaded with sulfuric acid at 15% concentration; e) Loaded with sulfuric acid at 20% concentration.

[0047] like Figure 6 Shown are the dynamic adsorption-desorption curves of the microfiber leather substrate, where a is the unmodified nonwoven fabric curve; b is the 20% sulfuric acid modified + loaded MOF curve.

[0048] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions only describe the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for preparing an asymmetric microfiber leather substrate based on MOF enhanced performance, characterized in that: The method comprises the following steps: The first step: the nonwoven fabric is modified with sulfuric acid. The sulfuric acid solution is evenly sprayed on the front side of the PET / PA6 hollow orange-shaped bi-component spunbond spunlace microfiber nonwoven fabric, and dried naturally at room temperature and pressure. The sulfuric acid solution achieves asymmetric modification of the nonwoven fabric through gravity. Step 2: adding aluminum chloride hexahydrate and 3,5-pyrazoledicarboxylic acid to deionized water and stirring until dissolved, placing the asymmetrically modified nonwoven fabric in the first step into the prepared solution, and adding a quantitative sodium hydroxide solution dropwise into the solution; Step 3: Seal the solution and react it at 90-100°C for 18-36 h; wash the non-woven fabric after the reaction with deionized water and methanol for 1-5 times, ultrasonicate for 1-4 h, and dry it in a vacuum oven to obtain an asymmetric microfiber leather substrate.

2. The method for preparing an asymmetric microfiber leather substrate based on MOF enhanced performance according to claim 1, characterized in that: Repeat the first step 0-3 times before proceeding to the second step.

3. The method for preparing an asymmetric microfiber leather substrate based on MOF enhanced performance according to claim 2, characterized in that: In the first step, the concentration of the sulfuric acid solution is 5-25wt%, and the content of each spraying is 3-8 g.

4. The method for preparing an asymmetric microfiber leather substrate based on MOF enhanced performance according to claim 1, characterized in that: In the second step, the concentration of aluminum chloride hexahydrate is 0.8-2.0 wt %, and the concentration of 3,5-pyrazoledicarboxylic acid is 0.6-1.7 wt %.

5. The method for preparing an asymmetric microfiber leather substrate based on MOF enhanced performance according to claim 1, characterized in that: The sodium hydroxide solution was prepared by mixing 2.6 g of sodium hydroxide with 30 ml of deionized water.

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