Modified nonwoven fabric and method for manufacturing and use thereof

Abstract

The application discloses a modified non-woven fabric and a preparation method and application thereof. The preparation method comprises the following steps: providing a non-woven fabric, wherein the non-woven fabric comprises a plurality of fibers, and the fibers have a crystal region and an amorphous region structure; and performing plasma etching treatment on the surface of the non-woven fabric to obtain a modified non-woven fabric with a fish scale-shaped structure; wherein the working voltage of the plasma etching treatment is 200-300 V. The non-woven fabric is treated by plasma etching, so that the modified non-woven fabric has excellent stability, the hydrophilic performance of the modified non-woven fabric lasts for at least two months, and the modified non-woven fabric can maintain self-cleaning after treating oil stains for many times, the surface of the modified non-woven fabric is free of oil stain residues, and the modified non-woven fabric can be reused. Meanwhile, the PECVD technology is simple to operate, simple in process, short in time consumption and suitable for large-scale preparation of the modified non-woven fabric.

Description

Technical Field

[0001] This invention belongs to the field of polymer material surface modification technology, and relates to a modified nonwoven fabric, its preparation method and application, and particularly to a superhydrophilic-underwater oleophobic modified nonwoven fabric, its preparation method and application. Background Technology

[0002] Non-woven fabric, also known as non-woven cloth, is composed of oriented or randomly arranged fibers. It is called cloth because it resembles the appearance and some properties of fabric. Non-woven fabrics are characterized by moisture resistance, breathability, flexibility, light weight, non-flammability, easy decomposition, non-toxicity, non-irritation, rich colors, low price, and recyclability. Commonly used polypropylene (PP) non-woven fabrics have many advantages, including low cost, light weight, simple processing, corrosion resistance, and good chemical stability. The development of industries such as food, pharmaceuticals, metallurgy, and chemicals has brought many conveniences to human life, but it has also brought various pollution problems. Oily wastewater generated in industrial production and daily life causes great damage to the ecological environment and may even endanger human safety. From the discharge of domestic sewage to the spill of marine oil, the harm is self-evident. How to efficiently and easily treat oily wastewater is a major problem. Humans have developed a series of oily wastewater purification technologies. Traditional oil-water separation methods generally have disadvantages such as complex preparation methods, low separation efficiency, high cost, and serious resource waste. Using an ultrawetting membrane to separate oil-water mixtures can avoid these problems.

[0003] Because the raw material PP fiber of polypropylene nonwoven fabric is almost non-absorbent and its molecular structure contains only regularly arranged methyl groups, lacking more functional groups and polar groups, its hydrophilicity is poor, which greatly limits its application as a functional material in medical and health care, wiping materials, battery separators, sewage treatment and other fields. Therefore, hydrophilic modification of the surface of polypropylene nonwoven fabric has important theoretical and practical application value. Currently, commonly used methods for nonwoven fabric surface modification include surface modification, physical blending modification, and chemical copolymerization modification. Surface modification involves directly depositing a layer of hydrophilic material or grafting hydrophilic polymers onto the polymer surface, while blending modification refers to adding additives during the polymer preparation process to improve performance. However, these modification methods generally have disadvantages such as complex preparation methods, high cost, and impact on matrix properties. The plasma modification technology used in this paper is simple to operate and environmentally friendly, and can avoid these problems. Summary of the Invention

[0004] The main objective of this invention is to provide a modified nonwoven fabric, its preparation method, and its application, in order to overcome the shortcomings of the prior art.

[0005] To achieve the aforementioned objectives, the technical solution adopted by this invention includes:

[0006] This invention provides a method for preparing modified nonwoven fabric, comprising:

[0007] A nonwoven fabric is provided, the nonwoven fabric comprising a plurality of fibers having a crystalline region and an amorphous region structure;

[0008] Furthermore, the surface of the nonwoven fabric is subjected to plasma etching treatment to obtain a modified nonwoven fabric with a fish-scale structure on the surface; wherein the working voltage used for the plasma etching treatment is 200-300V.

[0009] The present invention also provides a modified nonwoven fabric prepared by the aforementioned preparation method, wherein the surface of the modified nonwoven fabric has a fish-scale structure.

[0010] The present invention also provides the application of the aforementioned modified nonwoven fabric in oil-water separation.

[0011] This invention also provides a surface treatment method for improving the superhydrophilic-underwater oleophobic properties of nonwoven fabrics, comprising:

[0012] The nonwoven fabric is treated using the aforementioned preparation method to improve its superhydrophilic-underwater oleophobic properties.

[0013] This invention also provides an oil-water separation method, which includes: bringing the aforementioned modified nonwoven fabric into full contact with an oil-water mixture, wherein the modified nonwoven fabric can capture oil in the oil-water mixture, thereby achieving oil-water separation.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0015] (1) The present invention utilizes plasma etching to treat non-woven fabric, thereby making the modified non-woven fabric have excellent stability, its hydrophilicity lasts for at least two months, and it can still maintain its own cleanliness after multiple treatments of oil stains, with no oil stain residue on the surface, and can be reused.

[0016] (2) The present invention uses PECVD technology, which is simple to operate, easy to process, and short in time. It is suitable for large-scale preparation of modified nonwoven fabrics. At the same time, it uses oxygen to provide oxygen element, the raw material source is abundant and the price is low, which reduces the preparation cost. It can also introduce active functional groups to change the chemical composition of the substrate surface.

[0017] (3) The modified nonwoven fabric prepared in this invention can be used to treat oil stains. It is an environmentally friendly material that can be reused repeatedly, making it economical and environmentally friendly. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figures 1a-1b This is a scanning electron microscope image of the surface of the modified nonwoven fabric with a fish-scale structure formed after etching in Embodiment 1 of the present invention;

[0020] Figure 2 This is a scanning electron microscope image of the surface of the nonwoven fabric before etching in Comparative Example 1 of the present invention;

[0021] Figure 3 This is a scanning electron microscope image of the etched nonwoven fabric surface in Comparative Example 3 of the present invention;

[0022] Figures 4a-4b This is a water contact angle diagram of the modified nonwoven fabric in Example 1 of the present invention and the nonwoven fabric before etching in Comparative Example 1;

[0023] Figure 5 This is an underwater oil contact angle diagram of the unmodified nonwoven fabric in Comparative Example 1 of the present invention;

[0024] Figure 6 This is the underwater oil contact angle diagram of the modified nonwoven fabric in Embodiment 4 of the present invention. Detailed Implementation

[0025] In view of the deficiencies of the prior art, the inventors of this invention, through long-term research and extensive practice, have proposed the technical solution of this invention. The main technology used is low-temperature plasma modification, which is simple to operate and does not cause environmental pollution. Moreover, the plasma acts on the material surface at a depth of only tens of nanometers, which does not affect the properties of the matrix. It can process surfaces of various shapes and is a simple and effective method to improve hydrophilicity.

[0026] The technical solution of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] Specifically, as one aspect of the technical solution of this invention, a method for preparing a modified nonwoven fabric includes:

[0028] A nonwoven fabric is provided, the nonwoven fabric comprising a plurality of fibers having a crystalline region and an amorphous region structure;

[0029] Furthermore, the surface of the nonwoven fabric is subjected to plasma etching treatment to obtain a modified nonwoven fabric with a fish-scale structure on the surface; wherein the working voltage used for the plasma etching treatment is 200-300V.

[0030] In some preferred embodiments, the preparation method specifically includes:

[0031] The nonwoven fabric is placed on the cathode plate of a PECVD plasma device, a working gas is introduced, and then the surface of the nonwoven fabric is subjected to plasma etching treatment to obtain the modified nonwoven fabric.

[0032] The working gas has a flow rate of 80-120 sccm, a pressure of 150-250 mtorr, and an etching time of 1-60 min.

[0033] Furthermore, the nonwoven fabric includes any one or a combination of two of polypropylene nonwoven fabric and PET nonwoven fabric, and is not limited thereto.

[0034] Furthermore, the crystallinity of the fiber is 30% to 50%.

[0035] Furthermore, the working gas includes any one or a combination of two or more of argon, nitrogen, and oxygen, and is not limited thereto.

[0036] Furthermore, the working gas is oxygen.

[0037] Furthermore, the preparation method further includes: washing and drying the nonwoven fabric before performing the plasma etching treatment.

[0038] Furthermore, the washing process includes immersing the nonwoven fabric in acetone and / or ethanol.

[0039] Furthermore, the preparation method further includes: placing the nonwoven fabric in an acetone and / or ethanol solution, soaking for 3 minutes to remove impurities, ultrasonically cleaning with deionized water, and drying.

[0040] Furthermore, the preparation method further includes: before performing the plasma etching treatment, fixing the nonwoven fabric to the cathode plate of the PECVD plasma device and evacuating to a vacuum of 3×10⁻⁶. -5 Within Torr.

[0041] In this invention, plasma etching alters the surface morphology and functional groups of the nonwoven fabric. As etching time increases, the surface morphology changes gradually cover all fibers. An attractive force exists between the surface functional groups and water molecules, giving the nonwoven fabric superhydrophilic-oceanic oleophobic properties, suitable for oil-water separation. Simultaneously, active functional groups such as hydroxyl groups are generated on the surface, providing possibilities for further material modification. The fish-scale structure formed on the surface of the modified nonwoven fabric fibers is due to the presence of crystalline and amorphous regions in the nonwoven material, resulting in different etching rates in different areas. The highly ordered crystalline regions have higher bond energies and are more difficult to etch, thus the amorphous regions are etched first. By selecting an appropriate operating voltage, a fish-scale structure can be efficiently etched onto the surface of each fiber.

[0042] The reason why the modified nonwoven fabric exhibits superhydrophilic-underwater oleophobic properties in this invention is as follows: Before treatment, the nonwoven fabric is hydrophobic. During oxygen plasma treatment, impurities attached to the fiber surface are first etched away, reducing roughness and increasing hydrophilicity. As the etching time increases, the surface morphology of the material changes, roughness increases, and surface energy increases. At the same time, oxygen ions react with free radicals generated after the substrate surface is activated to form oxygen-containing functional groups such as hydroxyl and carboxyl groups. As the number of functional groups increases, the effect of surface chemical modification gradually exceeds the influence of roughness on surface wettability, and the substrate ultimately exhibits superhydrophilicity. After complete wetting, the surface of the nonwoven fabric is covered with a thick layer of water. Due to the lubricating effect of water, oil droplets on the nonwoven fabric surface will quickly slide off, leaving no oil droplet residue on the surface, demonstrating good oleophobicity.

[0043] Another aspect of the present invention provides a modified nonwoven fabric prepared by the aforementioned preparation method, wherein the surface of the modified nonwoven fabric has a fish-scale structure.

[0044] In some preferred embodiments, the surface of the modified nonwoven fabric has a contact angle of 0° with water.

[0045] Another aspect of the present invention provides the application of the aforementioned modified nonwoven fabric in oil-water separation.

[0046] Another aspect of the present invention provides a surface treatment method for improving the superhydrophilic-underwater oleophobic properties of nonwoven fabrics, comprising:

[0047] The nonwoven fabric is treated using the aforementioned preparation method to improve its superhydrophilic-underwater oleophobic properties.

[0048] This invention utilizes the structural characteristics of nonwoven fabrics, which are composed of fibers and contain both crystalline and amorphous regions. Different regions exhibit varying degrees of atomic order and bond energies, resulting in inconsistent atomic overflow rates during etching. This alters the surface morphology of the nonwoven fabric, giving it a fish-scale-like structure. The presence of this microstructure improves the material's wettability, significantly reducing the static contact angle of the nonwoven fabric. The raw material transforms from hydrophobic to superhydrophilic, and from underwater oleophilic to underwater oleophobic. The surface treatment method provided by this invention offers advantages such as ease of operation, significant hydrophilic modification effect, and good stability. Furthermore, the preparation process provided by this invention is simple, low-cost, environmentally friendly, and suitable for large-scale industrial production.

[0049] Another aspect of the present invention provides an oil-water separation method, comprising: bringing the aforementioned modified nonwoven fabric into full contact with an oil-water mixture, wherein the modified nonwoven fabric can capture oil in the oil-water mixture, thereby achieving oil-water separation.

[0050] The technical solution of the present invention will be further described in detail below with reference to several preferred embodiments and accompanying drawings. This embodiment is implemented on the premise of the technical solution of the invention, and provides detailed implementation methods and specific operation processes. However, the protection scope of the present invention is not limited to the following embodiments.

[0051] Unless otherwise specified, the experimental materials used in the examples below can be purchased from conventional biochemical reagent companies.

[0052] Example 1

[0053] The nonwoven fabric (polypropylene) was commercially available. The nonwoven fabric was immersed in acetone solution for 3 minutes to remove impurities, then ultrasonically cleaned with deionized water and dried. Afterward, it was adhered to the cathode plate of the PECVD plasma equipment using conductive adhesive, and a vacuum of 3 × 10⁻⁶ was applied. -5 Within a certain range (within Torr), oxygen was used as the working gas to etch the surface of the substrate, thereby modifying the surface of the nonwoven fabric and producing a modified nonwoven fabric. The oxygen flow rate was 100 sccm, the working voltage was 250V, the working gas pressure was 200 mtorr, and the etching time was 30 min. A scanning electron microscope image of the modified nonwoven fabric prepared in this embodiment is shown below. Figures 1a-1b As shown, the fiber surface of the modified nonwoven fabric is almost entirely etched (e.g., Figure 1a ), when magnified, it reveals a fish-scale-like porous structure (such as Figure 1b The comparison diagram of the water contact angle of the nonwoven fabric before and after etching is shown below. Figures 4a-4b As shown, the water contact angle of the nonwoven fabric before etching is 137° (e.g., Figure 4a The modified water contact angle is 0° (e.g., Figure 4bThe modified nonwoven fabric exhibits excellent stability due to its superhydrophilicity, lasting for at least two months. Even after two months in the air, the water contact angle remains at 0°. When oil is dripped onto the wetted modified nonwoven fabric and then immersed in water, the oil droplets quickly detach from the membrane upon immersion, leaving no oil residue on the membrane surface upon removal.

[0054] Comparative Example 1

[0055] The nonwoven fabric material (polypropylene) was commercially available and untreated. A scanning electron microscope image of the nonwoven fabric surface before etching is shown below. Figure 2 As shown, the contact angle diagram before etching is as follows: Figure 4a As shown, the underwater oil contact angle before etching is as follows: Figure 5 As shown.

[0056] Comparative Example 2

[0057] The nonwoven fabric (polypropylene) was commercially available. The nonwoven fabric was immersed in acetone solution for 3 minutes to remove impurities, then ultrasonically cleaned with deionized water and dried. Afterward, it was adhered to the cathode plate of the PECVD plasma equipment using conductive adhesive, and a vacuum of 3 × 10⁻⁶ was applied. -5 Within a range of Torr, oxygen is used as the working gas to etch the surface of the substrate, thereby modifying the surface of the nonwoven fabric. The oxygen flow rate is 100 sccm, the working voltage is 180V, the working gas pressure is 200 mtorr, and the etching time is 30 min.

[0058] Comparative Example 3

[0059] The nonwoven fabric (polypropylene) was commercially available. The nonwoven fabric was immersed in acetone solution for 3 minutes to remove impurities, then ultrasonically cleaned with deionized water and dried. Afterward, it was adhered to the cathode plate of the PECVD plasma equipment using conductive adhesive, and a vacuum of 3 × 10⁻⁶ was applied. -5 Within a range of Torr, oxygen was used as the working gas to etch the surface of the substrate, thereby modifying the surface of the nonwoven fabric. The oxygen flow rate was 100 sccm, the working voltage was 180V, the working gas pressure was 200 mtorr, and the etching time was 60 min. The scanning electron microscope image of the modified nonwoven fabric is shown below. Figure 3 As shown, some areas of the fiber surface of the modified nonwoven fabric are etched.

[0060] Comparative Example 4

[0061] The nonwoven fabric (polypropylene) was commercially available. The nonwoven fabric was immersed in acetone solution for 3 minutes to remove impurities, then ultrasonically cleaned with deionized water and dried. Afterward, it was adhered to the cathode plate of the PECVD plasma equipment using conductive adhesive, and a vacuum of 3 × 10⁻⁶ was applied. -5Within a range of Torr, oxygen is used as the working gas to etch the surface of the substrate, thereby modifying the surface of the nonwoven fabric. The oxygen flow rate is 100 sccm, the working voltage is 320V, the working gas pressure is 200 mtorr, and the etching time is 30 min. After etching, the surface of the nonwoven fabric appears burnt yellow, indicating that its structure has been damaged.

[0062] Example 2

[0063] The nonwoven fabric material was commercially available. The nonwoven fabric was immersed in acetone solution for 3 minutes to remove impurities, then ultrasonically cleaned with deionized water and dried. Afterwards, it was attached to the cathode plate of the PECVD plasma equipment with conductive adhesive, and a vacuum of 3 × 10⁻⁶ was applied. 5 Torr, using oxygen as the working gas, etches the surface of the substrate to modify the surface of the nonwoven fabric. The oxygen flow rate is 100 sccm, the working voltage is 250V, the working gas pressure is 200 mtorr, and the etching time is 1 min. The number of small particles on the surface of the etched nonwoven fabric is significantly reduced compared to the surface before etching.

[0064] Example 3

[0065] The non-woven fabric material was taken from the outermost layer of a 3M dust mask, model number 8210CN. The non-woven fabric was immersed in acetone solution for 3 minutes to remove impurities, then ultrasonically cleaned with deionized water and dried. Afterward, it was attached to the cathode plate of the PECVD plasma equipment with conductive adhesive, and a vacuum of 3×10⁻⁶ was applied. -5 Within a range of Torr, oxygen is used as the working gas to etch the surface of the substrate, thereby modifying the surface of the nonwoven fabric. The oxygen flow rate is 100 sccm, the working voltage is 250V, the working gas pressure is 200 mtorr, and the etching time is 5 min.

[0066] Example 4

[0067] The nonwoven fabric material was commercially available. The nonwoven fabric was immersed in acetone solution for 3 minutes to remove impurities, then ultrasonically cleaned with deionized water and dried. Afterwards, it was attached to the cathode plate of the PECVD plasma equipment with conductive adhesive, and a vacuum of 3 × 10⁻⁶ was applied. -5 Within a certain range (within Torr), oxygen was used as the working gas to etch the surface of the substrate, thereby modifying the surface of the nonwoven fabric. The oxygen flow rate was 100 sccm, the working voltage was 250V, the working gas pressure was 200 mtorr, and the etching time was 15 min. The underwater oil contact angle diagram of the etched nonwoven fabric is shown below. Figure 6 As shown, the underwater oil contact angle after etching is 133° (e.g., Figure 6 ).

[0068] In addition, the inventors of this case also conducted experiments with other raw materials, process operations, and process conditions described in this specification, referring to the aforementioned embodiments, and obtained relatively ideal results in all cases.

[0069] It should be understood that the technical solutions of the present invention are not limited to the specific embodiments described above. Any technical modifications made to the technical solutions of the present invention without departing from the spirit and scope of the claims are within the scope of protection of the present invention.

Claims

1. A method for preparing a modified nonwoven fabric, characterized in that, include: A nonwoven fabric is provided, the nonwoven fabric comprising a plurality of fibers, the fibers having crystalline and amorphous regions; the crystallinity of the fibers is 30% to 50%; Furthermore, the nonwoven fabric is placed on the cathode plate of a PECVD plasma device, a working gas is introduced, and then the surface of the nonwoven fabric is subjected to plasma etching treatment to obtain a modified nonwoven fabric with a fish-scale structure on the surface; wherein, the working voltage of the plasma etching treatment is 200-300V, the flow rate of the working gas is 80-120sccm, the pressure of the working gas is 150-250mtorr, and the etching time is 1-60min; The modified nonwoven fabric has a fish-scale-like structure on its surface; the contact angle between the surface of the modified nonwoven fabric and water is 0°.

2. The preparation method according to claim 1, characterized in that: The nonwoven fabric includes any one or a combination of two of polypropylene nonwoven fabric and PET nonwoven fabric. The crystallinity of the fiber is 30% to 50%.

3. The preparation method according to claim 1, characterized in that: The working gas includes any one or a combination of two or more of argon, nitrogen, and oxygen.

4. The preparation method according to claim 1, characterized in that, Also includes: Before performing the plasma etching process, the nonwoven fabric is first washed and dried; wherein, the washing process includes immersing the nonwoven fabric in acetone and / or ethanol.

5. The preparation method according to claim 1, characterized in that, Also includes: Before performing the plasma etching process, the non-woven fabric is fixed to the cathode plate of the PECVD plasma device, and a vacuum of 3×10⁻⁶ is applied. -5 Within Torr.

6. The modified nonwoven fabric prepared by any one of claims 1-5.

7. The application of the modified nonwoven fabric according to claim 6 in oil-water separation.

8. A surface treatment method for improving the superhydrophilic-underwater oleophobic properties of nonwoven fabrics, characterized in that, include: The nonwoven fabric is treated using the preparation method described in any one of claims 1-5, thereby improving the superhydrophilic-underwater oleophobic properties of the nonwoven fabric.

9. A method for separating oil and water, characterized in that, include: The modified nonwoven fabric described in claim 6 is brought into full contact with the oil-water mixture to achieve oil-water separation.

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