KR20230081320A - PTFE-SiO2 nanofiber membrane for gas filter with excellent breathability and mechanical properties - Google Patents

Abstract

The present invention is a PTFE-SiO2 nanofibrous membrane prepared by electrospinning of a spinning solution, wherein the SiO2 nanoparticles are amorphous silica, further comprising 0.001 to 0.05 parts by weight based on 100 parts by weight of the spinning solution, and the nanofibrous membrane The nanofiber diameter constituting is 400 to 600 nm, and the tensile strength of the nanofiber membrane is 2 to 3.3 MPa, characterized in that it provides a PTFE-SiO2 nanofiber membrane for a gas filter.
The present invention shows sufficient air permeability in the PTFE/SiO ₂ nanofiber composite membrane even when the added amount of the silica nanostructure is very small. In addition, in the evaluation of mechanical properties, the tensile strength, elongation at break, and Young's modulus of the composite membrane are all improved compared to pure PTFE nanofibers according to the silica content. The electrospinning-based PTFE-SiO ₂ nanofiber composite membrane can be fabricated with a very simple process and has excellent air permeability and mechanical properties, so it can be applied as a gas filter.

Description

PTFE-SiO2 nanofiber membrane for gas filter with excellent breathability and mechanical properties}

The present invention relates to a PTFE-SiO2 nanofiber membrane for gas filters having excellent air permeability and mechanical properties. it's about something

Polyterafluoroethylene (PTFE) is well known for its excellent thermal stability, chemical resistance and electrical insulation properties. Due to their high flexibility and permeability, PTFE nanofibrous membranes have been widely used as high-temperature filter materials. However, it is difficult to fabricate a nanofibrous membrane through electrospinning using a PTFE solution because it has excellent solvent resistance and a high melting point. As one strategy to solve this problem, research on preparing a Teflon amorphous fluoropolymer composite membrane using a coaxial electrospinning method has been conducted. This method can electrospin a polymer material that cannot be electrospun, which is a shell solution, along the guide core polymer. Another method for producing a PTFE fiber membrane is electrospinning using an emulsion. In the emulsion electrospinning method, a small amount of water-soluble polymer and a guide polymer can be added to prepare a PTFE fiber membrane through an aqueous emulsion. A study on manufacturing a porous fiber membrane using polyvinyl alcohol (PVA) and a PTFE emulsion solution was conducted. In this study, uniform fibers were prepared at a PVA and PTFE mass ratio of 30:70 wt%, but the fiber structure was greatly deformed during sintering due to the high PVA content. Polyethylene oxide (PEO) was used as an effective guide polymer to minimize the defects of the fiber membrane. Since the fiber can be prepared by adding a low content of PEO, it has advantages such as maintenance of the fiber structure after sintering and easy removal by sintering. Afterwards, research was conducted to fabricate defect-free PTFE fiber membranes using a small amount of polyethylene oxide (PEO) as a guide polymer. The pure PTFE fiber membrane prepared by high-temperature sintering after electrospinning of PTFE and 3 wt% PEO-added emulsion showed excellent mechanical performance due to low structural defects. In addition, it showed excellent chemical resistance because it could have the same fiber shape and mechanical properties even after treatment with strong base and strong acid.

However, despite the high potential application of PTFE to filters, problems such as high linear coefficient of thermal expansion and low surface energy are still big problems. Therefore, inorganic fillers such as micro fiberglass and ceramic particles were added to the PTFE matrix. Therefore, studies were conducted to analyze the properties of PTFE/nano-silica composites (composites) such as heat, tensile strength and structure according to the filler content. As the filler content of various sizes increased from 0 to 60 wt%, the tensile modulus increased, but the tensile strength decreased. In this case, poor adhesion between the micro-sized silica filler and the matrix was the main cause of low tensile properties and thermal stability.

Republic of Korea Patent No. 10-0890594

In order to solve the above problems, an object of the present invention is to provide a PTFE/silica composite nanofibrous membrane and a manufacturing method through electrospinning using amorphous silica as a filler in order to have a membrane having high mechanical properties. .

In order to achieve the above object, the present invention,

A PTFE-SiO2 nanofiber membrane prepared by electrospinning of a spinning solution,

The SiO2 nanoparticles are amorphous silica, further comprising 0.001 to 0.05 parts by weight based on 100 parts by weight of the spinning solution,

The diameter of the nanofiber is 400 to 600 nm,

The tensile strength of the nanofibers provides a PTFE-SiO2 nanofiber membrane for gas filters, characterized in that 2 to 3.3 MPa.

The spinning solution is polytetrafluoroethylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyacrylonitrile, polyvinylidene chloride-acrylonitrile copolymer, polyethylene oxide, polyurethane, Polymethyl acrylate, polymethyl methacrylate, polyacrylamide, polyvinyl chloride, polyvinyl acetate, polyvinylpyrrolidone, polytetraethylene glycol diacrylate, polyethylene glycol dimethacrylate, cellulose, consisting of cellulose acetate It is preferable to include at least one selected from the group.

The air permeability of the nanofibrous membrane is preferably 800 to 1100 cc/sec.

In order to achieve the above other object, the present invention,

A first step of preparing a PEO solution by dissolving polyethyleneoxide (PEO) in a solvent;

A second step of preparing an electrospinning solution by mixing the PEO solution obtained in the above step and the polytetrafluoroethylene (PTFE) dispersion aqueous solution at a ratio of 1:5 to 15;

A third step of further adding 0.001 to 0.05 parts by weight of amorphous silicon oxide powder to the mixed solution based on 100 parts by weight of the electrospinning solution;

A fourth step of preparing a nanofibrous membrane by electrospinning the mixed solution;

A fifth step of removing PEO through a high-temperature sintering process by heat-treating the nanofiber membrane at 50 to 4000° C.

In the present invention, a PTFE/SiO ₂ nanofiber composite membrane is prepared by briefly sintering a PTFE-PEO/SiO ₂ nanofiber composite material prepared by electrospinning of a PTFE-PEO mixed solution to which a very small amount of amorphous silica nanostructure is added at high temperature. to provide. The PTFE/SiO ₂ nanofiber composite membrane shows sufficient air permeability even when the added amount of the silica nanostructure is very small. In addition, in the evaluation of mechanical properties using a universal testing machine, the tensile strength, elongation at break and Young's modulus at break of the composite membrane are all improved compared to pure PTFE nanofibers according to the silica content. The electrospinning-based PTFE-SiO ₂ nanofiber composite membrane can be fabricated with a very simple process and has excellent air permeability and mechanical properties, so it can be applied as a gas filter.

1 is an image of a PTFE-PEO/SiO ₂ composite nanofibrous membrane according to an embodiment of the present invention (a) before sintering and (b) after sintering.
2 is a PEO-PTFE/SiO ₂ composite nanofibrous membrane having a silica content of (a) 0.003, (b) 0.01, (c) 0.017, and (d) 0.033 wt% according to an embodiment of the present invention. This is a SEM image of SiO ₂ nanofibers.
FIG. 3 is a SEM image of PTFE/SiO ₂ nanofibers having silica contents of (a) control, (b) 0.003, (c) 0.01, and (d) 0.017 wt% according to an embodiment of the present invention.
4 is a pore distribution diagram of PTFE/SiO ₂ nanofibrous membranes having silica content of (a) 0 (control), (b) 0.003, (c) 0.01, and (d) 0.017 wt% according to an embodiment of the present invention. it's a graph
5 is a graph showing the gas flow rate according to the pressure change of the PTFE/SiO ₂ nanofiber membrane according to an embodiment of the present invention.
6 is a stress-strain curve of PTFE/SiO ₂ nanofibrous membranes having silica contents of (a) 0 (control), (b) 0.003, (c) 0.01, and (d) 0.017 wt% according to an embodiment of the present invention. it's a graph
7 is a graph of (a) tensile strength and (b) Young's modulus of a PTFE/SiO ₂ nanofibrous membrane for each silica content according to an embodiment of the present invention.

Hereinafter, the present invention will be described in more detail.

According to one aspect of the present invention, a PTFE-SiO2 nanofiber membrane prepared by electrospinning of a spinning solution, wherein the SiO2 nanoparticle is an amorphous silica, further comprising 0.001 to 0.05 parts by weight based on 100 parts by weight of the spinning solution, Provided is a PTFE-SiO2 nanofiber membrane for a gas filter, characterized in that the diameter of the nanofiber is 400 to 600 nm, and the tensile strength of the nanofiber is 2 to 3.3 MPa.

Preferably, SiO2 nanoparticles may further include 0.001 to 0.03 parts by weight based on 100 parts by weight of the spinning solution, and more preferably 0.001 to 0.02 parts by weight based on 100 parts by weight of the spinning solution.

If SiO2 nanoparticles are less than 0.001 part by weight, SiO2 nanoparticles are not sufficient, so it is difficult to increase mechanical properties such as elongation at break, tensile strength and Young's modulus, and if it exceeds 0.05 parts by weight, compatibility between SiO2 and PTFE is low, As more hydrophilic SiO2 nanoparticles are added, the filler-filler interaction increases and the filler-matrix interaction decreases. In addition, the low aspect ratio of SiO2 nanoparticles cannot support the stress transferred from PTFE to the fiber structure.

The spinning solution is polytetrafluoroethylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyacrylonitrile, polyvinylidene chloride-acrylonitrile copolymer, polyethylene oxide, polyurethane, poly A group consisting of methyl acrylate, polymethyl methacrylate, polyacrylamide, polyvinyl chloride, polyvinyl acetate, polyvinylpyrrolidone, polytetraethylene glycol diacrylate, polyethylene glycol dimethacrylate, cellulose, and cellulose acetate It is preferable to include one or more selected from.

More preferably, the spinning solution is polyethylene oxide and polytetrafluoroethylene, and the ratio of the spinning solution is preferably a mixture of PEO:PTFE in a ratio of 1:5 to 15.

The air permeability of the nanofibrous membrane is preferably 800 to 1100 cc/sec.

The elongation of the nanofibrous membrane according to the present invention is preferably 140 to 200%, more preferably 150 to 190%.

The Young's modulus of the nanofibrous membrane according to the present invention may be 50 to 80 N/mm ² .

The pore distribution of the nanofibrous membrane according to the present invention shows a distribution rate of 10 to 25% at 0.1 to 0.2 μm and 15 to 30% at 0.4 to 0.6 μm, respectively. Preferably, the pore distribution shows a distribution ratio of 10 to 20% at 0.1 to 0.2 μm and 15 to 30% at 0.4 to 0.6 μm, respectively.

According to another aspect of the present invention, a first step of preparing a PEO solution by dissolving polyethyleneoxide (PEO) in a solvent; A second step of preparing an electrospinning solution by mixing PEO and polytetrafluoroethylene (PTFE) at a ratio of 1:5 to 15; A third step of further adding 0.001 to 0.05 parts by weight of amorphous silicon oxide powder to the mixed solution based on 100 parts by weight of the electrospinning solution; A fourth step of preparing a nanofibrous membrane by electrospinning the mixed solution; and a fifth step of heat-treating the nanofiber membrane at 250 to 450° C. to remove PEO through a high-temperature sintering process.

In the second step, the electrospinning solution is preferably mixed with solvent: (PEO/PTFE) at a ratio of 2:8 to 5:5.

In the fifth step, it is preferable to preheat the nanofibers at 60 to 100° C. and heat-treat at 250 to 450° C. for 10 minutes.

Thermal degradation of PEO with a molecular weight of 600,000 g/mol does not occur below 200°C, and the main degradation process is known to be between 225-450°C. At a sintering temperature of 350 °C, the residual mass was found to be about 20%. PEO is almost completely decomposed at a sintering temperature of about 310 °C.

Melting of PEFE begins at about 320°C and is chemically stable below 480°C. Moreover, high viscosity PTFE melts (10 ¹¹ Pa·s) may not sufficiently fill micro/nanopores with low sintering temperature and short sintering time. At high sintering temperature and long sintering time, the molecular chain of PTFE can be thermally decomposed, which can degrade the mechanical performance of the membrane. Therefore, the sintering temperature is preferably 250 to 450 ℃.

Hereinafter, the composition is omitted because it is the same as the above-mentioned nanofibrous membrane.

In the present specification, when a certain component is said to "include", it means that it may further include other components without excluding other components unless otherwise stated. And terms used in this specification are for describing the embodiments, and are not intended to limit the present invention. In this specification, the singular form also includes the plural form unless specifically stated in the phrase.

In this document, expressions such as “A or B,” “at least one of A and/and B,” or “one or more of A or/and B” may include all possible combinations of the items listed together. . For example, “A or B,” “at least one of A and B,” or “at least one of A or B” (1) includes at least one A, (2) includes at least one B, Or (3) may refer to all cases including at least one A and at least one B.

Hereinafter, the present invention will be described in more detail with reference to preferred embodiments. However, these examples are intended to explain the present invention in more detail, and it will be apparent to those skilled in the art that the scope of the present invention is not limited thereto.

<Example>

reagents and materials

A 60 wt % PTFE dispersion aqueous solution and PEO (M _v = 600,000) were purchased from Sigma Aldrich Co. (USA). Amorphous silicon oxide powder (97.3+ wt %, 15 nm, 2 wt % silane coating) was purchased from AVENTION Co. (Korea).

Example 1 - Electrospinning Solution Preparation

A mixed solution for electrospinning was prepared according to the following procedure. 15.6 g of distilled water and 900 mg of PEO were put in a 100 mL vial and stirred at 600 rpm for 4 hours. Sequentially, 13.5 g of the PTFE dispersion aqueous solution and 0, 1, 3, and 5 mg of amorphous silicon oxide powder were added to the mixed solution and further stirred at 600 rpm for 4 hours.

Example 2 - PTFE-PEO/SiO ₂ Fabrication of nanofibrous membranes

In the present invention, a PTFE-PEO/SiO ₂ nanofiber membrane was prepared using electrospinning equipment (ESR200R1, Nano NC Co., Korea). The electrospinning device is composed of a high-voltage supply device, a solution ejection unit, and a collector. 10 mL of the prepared electrospinning solution was put into a 12 mL syringe and a 5 hole multi-nozzle device was coupled with the syringe. A nozzle having a nozzle gauge of 21 and an inner diameter of 0.5 mm was coupled to the multi-nozzle device, and then a high voltage supply device was connected to the multi-nozzle device. After fixing the aluminum foil to the drum collector, the nanofibers were collected for 8 hours while rotating at 100 rpm. Electrospinning was performed under conditions of a voltage of 11 kV, a flow rate of 20 μL/min, and a distance of 15 cm between the nozzle and the drum collector. The collected PTFE-PEO/SiO ₂ nanofibers were cut into 20 cm wide and 30 cm long, separated from the foil, and pre-heated at 80 °C. Finally, the PTFE-PEO/SiO ₂ nanofibers were annealed at 350 °C for 10 minutes using an electric furnace (muffle furnace, MF-31G, CANATECH Co.).

Example 3 - Morphology measurement

The morphology of the PTFE-PEO/SiO ₂ nanofibrous membrane was confirmed using Hitachi High-Technology's S-4800 field emission scanning electron microscopy (FE-SEM). Samples were prepared by cutting the membrane into 1 cm wide and 1 cm long. All samples were surface coated with platinum for 60 seconds.

Example 4 - Measurement of permeability and pore size distribution

The permeability and pore distribution of the PTFE-PEO/SiO ₂ nanofibrous membrane were measured using a capillary flow porometer (CFP-1500AEL, Porous Material Inc.). Samples for transmittance measurement were prepared with a diameter of 0.9 cm and a thickness of 0.018-0.02 cm.

Example 5 - Measurement of tensile strength and elongation at break

The tensile strength and elongation at break of the PTFE-PEO/SiO ₂ nanofibrous membrane were measured using a universal testing machine (UTM). Specimens were prepared according to the ASTM D882 standard with a thickness of 0.120.234 mm and a width of 9.6113.13 mm.

<Results and evaluation>

PTFE-PEO/SiO ₂ Comparison of nanofiber membranes

PTFE-PEO/SiO ₂ composite nanofibrous membranes were prepared with silica contents of 0 (control), 0.003, 0.01 and 0.17 wt%. 1 is an image of a PTFE-PEO/SiO ₂ composite nanofibrous membrane according to an embodiment of the present invention (a) before sintering and (b) after sintering. 2 is a PEO-PTFE/SiO ₂ composite nanofibrous membrane having a silica content of (a) 0.003, (b) 0.01, (c) 0.017, and (d) 0.033 wt% according to an embodiment of the present invention. This is a SEM image of SiO ₂ nanofibers. PEO:PTFE=1:9 (30wt%) 30 g, 8 hours Electrospun membrane diameter.

Referring to FIG. 2, as the amount of Silica increases, the viscosity of the solution increases, and as the viscosity increases, the diameter of the fiber increases. However, errors may occur depending on conditions during electrospinning (ex Nozzle inner diameter, Tip to collector distance, applied voltage) and conditions during sintering (temperature and time). However, the electrospinning conditions were the same, and the sintering was started at 310 ° C and heated for 6 minutes at 350 ° C, which is higher than the PEO melting point of 65 ° C and the PTFE melting point of 327 ° C. Therefore, PEO, the sacrificial material, must have been sufficiently decomposed, and PTFE could have been melted and fused again to form fibers. Therefore, PEO present in the membrane was removed through preheating at 80 °C and high-temperature sintering at 350 °C.

During this process, micro/nano pores were formed in the fiber, and the PTFE melt was diffused to fill the micro/nano pores, finally forming a control PTFE fiber. Therefore, it was found that the sintering temperature and sintering time are important factors for forming pure PTFE fibers. PEO having a molecular weight of 600,000 g/mol does not undergo thermal degradation below 200°C, and the main degradation process is known to be between 225 and 450°C. At a sintering temperature of 350 °C, the residual mass was found to be about 20%. In some other studies, PEO was almost completely decomposed at a sintering temperature of about 310 °C. Melting of PTFE begins at about 320°C and is chemically stable below 480°C. In addition, high viscosity PTFE melts (10 ¹¹ Pa*?*s) may not sufficiently fill micro/nanopores with low sintering temperatures and short sintering times. At high sintering temperature and long sintering time, the molecular chain of PTFE can be thermally decomposed, which can degrade the mechanical performance of the membrane. Therefore, appropriate sintering temperature and sintering time were applied. After the sintering process, the membrane shrank due to the fluidity of the PTFE melt. The size of the nanofibrous membrane observed with the naked eye was reduced by about 40% (Fig. 1b).

Surface morphology analysis

The surface morphology of the membrane was analyzed after sintering, since the presence of beads and non-uniform fiber morphology in the membrane can lead to reduced mechanical performance and permeability. 3 is a SEM image of PTFE/SiO ₂ nanofibers having silica contents of (a) 0 (control), (b) 0.003, (c) 0.01, and (d) 0.017 wt% according to an embodiment of the present invention. As shown in a of FIG. 3, the control PTFE nanofibers were uniform without the presence of beads, and the average diameter was confirmed to be 529.6 nm. Composite nanofibers containing silica also showed high uniformity, with average diameters of 429, 449.5, and 556.4 for silica contents of 0.003, 0.01, and 0.017 wt% ((b), (c), and (d) in Fig. 3), respectively. appeared in nm.

As the amount of silica increases, the viscosity of the solution increases, and as the viscosity increases, the diameter of the fiber increases. Assuming that the fiber is packed with a uniform density, the average pore diameter should decrease as the fiber diameter increases. Referring to FIG. 3, when silica is not added (control group), the fibers are not agglomerated and stretched well in a linear manner. If you look at the SEM picture of the fibers to which silica is added, an interlocked structure in which the fibers are agglomerated is observed It became. This structural difference affected porosity and tensile strength.

Analysis of permeability and pore size distribution

4 is a pore distribution diagram of PTFE/SiO ₂ nanofibrous membranes having silica content of (a) 0 (control), (b) 0.003, (c) 0.01, and (d) 0.017 wt% according to an embodiment of the present invention. it's a graph Referring to FIG. 4, it was confirmed that the control PTFE membrane had various pore size distributions in the range of 0-1.7 μm. It showed a relatively high distribution rate of 16.7% in the area of about 0.1-0.2 μm.

However, the pore size distribution of the PTFE/SiO ₂ membrane was relatively narrow in the range of 0-1.2 μm. Interestingly, a high pore distribution of the PTFE/SiO ₂ nanofibrous membranes was observed in both the 0.1-0.2 and 0.4-0.5 μm regions. In general, in a PTFE/silica composite membrane, silica can inhibit the fluidity of PTFE during sintering, resulting in an increase in pore size. The PTFE/SiO ₂ membrane with a silica content of 0.003 wt% showed the highest distribution rate of 25.5% in the range of 0.4–0.5 μm, and the membranes with a silica content of 0.01 and 0.017 wt% were found to be 17.8 and 17.2%, respectively.

5 is a graph showing the gas flow rate according to the pressure change of the PTFE/SiO ₂ nanofiber membrane according to an embodiment of the present invention. The capillary flow porometer test results are shown in Table 1 below.

Mean flow pore diameter is the median value of the measured pore size and is calculated from the point where the half dry curve and the wet curve meet. The bubble point is the first pressure point where Galwick emerges. From this, the maximum pore size is calculated.

Referring to FIG. 5 and Table 1, the gas flow rate of the PTFE nanofiber membrane without silica as a control group was 1237.4 cc/sec, showing the highest air permeability. The gas flow rate decreased as the silica content increased, and was found to be 1014.6, 982.6, and 867.5 cc/sec for the 0.003, 0.01, and 0.017 wt% contents, respectively. When the silica content reached about 7.3 and 10 wt% or more, the air permeability increased significantly, but at the 4.6 and 2 wt% contents, the air permeability rather decreased.

In addition, it was observed that the gas permeability at the same PSI decreased as the silica content increased. In particular, when 5mg (0.017wt%) was added compared to when Silica was not added, it was found that it decreased by about one-third. It can be expected that the permeability decreased because the viscosity increased as more silica was added, and the pore size decreased as the diameter of the electrospun fiber increased.

In the present invention, it was determined that the PTFE nanofiber membrane (control group) was influenced by having a relatively wide pore distribution compared to the PTFE/SiO ₂ nanofibers.

Mechanical property analysis

Mechanical properties were evaluated to confirm the effect of adding silica to the PTFE/SiO ₂ membrane.

6 is a stress-strain curve of PTFE/SiO ₂ nanofibrous membranes having silica contents of (a) 0 (control), (b) 0.003, (c) 0.01, and (d) 0.017 wt% according to an embodiment of the present invention. it's a graph 7 is a graph of (a) tensile strength and (b) Young's modulus of a PTFE/SiO ₂ nanofibrous membrane for each silica content according to an embodiment of the present invention. Table 2 below is a table summarizing the test results of tensile strength.

Referring to Table 2 and FIG. 6, the strength of the PTFE/SiO ₂ membrane containing 0.003-0.017 wt% silica was significantly improved compared to the control PTFE membrane. Referring to FIG. 7, the tensile strength of the PTFE/SiO ₂ membrane containing 0.003 wt% silica was the highest at 2.93±0.11 MPa among all samples, and was more than 4.05 times higher than that of the control PTFE pure membrane (Fig. 7 a). This is considered to be because the silica present in the membrane plays an important role in absorbing energy and dispersing strength. However, when the silica content was increased to 0.01 and 0.017 wt%, the tensile strength of the membrane slightly decreased to 2.68±0.12 and 2.34±0.23 MPa, respectively. It is conceivable that some silica agglomerates adversely affect the membrane. Therefore, introducing silica into the membrane could effectively improve the strength.

In addition, the breaking elongation increased as the silica content increased from 0.003 to 0.017 wt%, and when the silica content was 0.017 wt%, the elongation at break was 180±31%, which was 2 doubled. In general, as the silica content increases, the elongation at break tends to decrease due to the decrease in flexibility of the composite membrane. However, the introduction of very low weight silica can prevent the formation of large silica agglomerates in the polymer matrix, resulting in an increase in both the tensile strength and the elongation at break of the structurally defect-free, stable composite membrane. Figure 7 (b) shows the calculated Young's modulus. Similar to the trend of tensile strength, Young's modulus values were higher than those of pure PTFE in all membranes with silica content, and the Young's modulus for the silica content of 0.003 wt% was the highest at 80 ± 24 MPa.

In the present invention, a PTFE/SiO ₂ nanofiber composite membrane was successfully prepared by introducing a very small amount of silica nanostructure and sintering the electrospun nanofiber at 350° C. for 10 minutes. The average fiber diameters of the membranes ranged from 429 to 556.4 nm. The PTFE/SiO ₂ nanofiber composite membrane with an added amount of 0.003 wt% of the silica nanostructure, which is a kind of filler, exhibited a relatively moderate air permeability of 1014.6 cc/sec. In addition, the tensile strength, elongation at break, and Young's modulus of the silica-containing PTFE/SiO ₂ nanofibrous membrane were all improved compared to the control pure PTFE nanofibrous membrane. Therefore, it was found that the introduction of a very small amount of silica nanostructures into the PTFE membrane contributed greatly to the improvement of the mechanical properties of the pure PTFE membrane.

The foregoing has outlined rather broadly the features and technical advantages of the present invention in order that the scope of the invention which follows may be better understood. Those skilled in the art to which the present invention pertains will understand that the present invention can be embodied in other specific forms without changing its technical spirit or essential features. Therefore, the embodiments described above should be understood as illustrative in all respects and not limiting. The scope of the present invention is indicated by the following claims rather than the above detailed description, and all changes or modifications derived from the claims and equivalent concepts should be construed as being included in the scope of the present invention.

Claims (5)

A PTFE-SiO2 nanofiber membrane prepared by electrospinning of a spinning solution,
The SiO2 nanoparticles are amorphous silica, further comprising 0.001 to 0.05 parts by weight based on 100 parts by weight of the spinning solution,
The diameter of the nanofibers constituting the nanofibrous membrane is 400 to 600 nm,
PTFE-SiO2 nanofiber membrane for gas filter, characterized in that the tensile strength of the nanofiber membrane is 2 to 3.3 MPa.
According to claim 1,
The spinning solution is polytetrafluoroethylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyacrylonitrile, polyvinylidene chloride-acrylonitrile copolymer, polyethylene oxide, polyurethane, Polymethyl acrylate, polymethyl methacrylate, polyacrylamide, polyvinyl chloride, polyvinyl acetate, polyvinylpyrrolidone, polytetraethylene glycol diacrylate, polyethylene glycol dimethacrylate, cellulose, consisting of cellulose acetate PTFE-SiO2 nanofiber membrane for gas filter, characterized in that it comprises at least one selected from the group.
According to claim 2,
The spinning solution is a PTFE-SiO2 nanofiber membrane for gas filters, characterized in that polyethylene oxide and polytetrafluoroethylene are mixed in a ratio of 1: 5 to 15.
According to claim 1,
PTFE-SiO2 nanofiber membrane for gas filter, characterized in that the air permeability of the nanofiber membrane is 800 to 1100 cc / sec.
A first step of preparing a PEO solution by dissolving polyethyleneoxide (PEO) in a solvent;
A second step of preparing an electrospinning solution by mixing the PEO and polytetrafluoroethylene (PTFE) at a ratio of 1:5 to 15;
A third step of further adding 0.001 to 0.05 parts by weight of amorphous silicon oxide to the mixed solution based on 100 parts by weight of the electrospinning solution;
A fourth step of preparing a nanofibrous membrane by electrospinning the mixed solution; and
A method for manufacturing a PTFE-SiO2 nanofiber membrane for a gas filter comprising a fifth step of heat-treating the nanofiber membrane at 50 to 4000° C. to remove PEO through a high-temperature sintering process.

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