CN114534519A - Low-resistance high-efficiency filter membrane and manufacturing method thereof - Google Patents
Low-resistance high-efficiency filter membrane and manufacturing method thereof Download PDFInfo
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- -1 polytetrafluoroethylene Polymers 0.000 claims abstract description 75
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- NIPNSKYNPDTRPC-UHFFFAOYSA-N N-[2-oxo-2-(2,4,6,7-tetrahydrotriazolo[4,5-c]pyridin-5-yl)ethyl]-2-[[3-(trifluoromethoxy)phenyl]methylamino]pyrimidine-5-carboxamide Chemical compound O=C(CNC(=O)C=1C=NC(=NC=1)NCC1=CC(=CC=C1)OC(F)(F)F)N1CC2=C(CC1)NN=N2 NIPNSKYNPDTRPC-UHFFFAOYSA-N 0.000 description 1
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
- B01D71/06—Organic material
- B01D71/30—Polyalkenyl halides
- B01D71/32—Polyalkenyl halides containing fluorine atoms
- B01D71/36—Polytetrafluoroethene
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
- B01D67/0002—Organic membrane manufacture
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
- B01D69/02—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor characterised by their properties
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2323/00—Details relating to membrane preparation
- B01D2323/39—Electrospinning
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2325/00—Details relating to properties of membranes
- B01D2325/12—Adsorbents being present on the surface of the membranes or in the pores
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2325/00—Details relating to properties of membranes
- B01D2325/26—Electrical properties
Abstract
The application relates to the field of filter membrane materials, and particularly discloses a low-resistance high-efficiency filter membrane and a manufacturing method thereof. The fiber mesh layer of the low-resistance high-efficiency filter membrane is formed by an electrostatic spinning method; the electrostatic spinning solution is prepared from water, water-soluble high-molecular polymer and polytetrafluoroethylene emulsion; the sum of the contents of the water-soluble high molecular polymer and the polytetrafluoroethylene accounts for 25-35wt% of the total amount of the electrostatic spinning solution, and the weight ratio of the water-soluble high molecular polymer to the polytetrafluoroethylene is 3.5 (6.4-7.5); the low-resistance high-efficiency filter membrane also comprises a first non-woven fabric layer and a second non-woven fabric layer. The low-resistance high-efficiency filter membrane still has high filtering efficiency in a high-humidity environment and has long service life. The application also correspondingly discloses a preparation method of the low-resistance high-efficiency filter membrane, which comprises an electrostatic spinning solution preparation step, an electrostatic spinning step, a polytetrafluoroethylene membrane compounding step and a non-woven fabric layer compounding step.
Description
Technical Field
The application relates to the field of filter membrane materials, in particular to a low-resistance high-efficiency filter membrane and a manufacturing method thereof.
Background
The PTFE microporous membrane takes polytetrafluoroethylene as a raw material, and forms a microporous membrane after expansion and stretching, has good filtering effect, and is a filtering material widely applied to high-efficiency and ultra-high-efficiency filter membranes. But the PTFE filter material has larger resistance and generates larger energy consumption in the using process. The PTFE microporous membrane has limited filtration efficiency improvement with increasing thickness, but significant resistance improvement and significant cost increase. Therefore, it is a problem how to reduce the manufacturing cost of the filter material and improve the filtration efficiency.
The electrostatic spinning nano-fiber has extremely fine fiber diameter, higher specific surface area, higher porosity and stronger adsorption force, has good filtering effect on fine particles, and has smaller resistance in the running process. The technology of preparing the filter material by combining the electrostatic spinning nano-fiber and the PTFE microporous membrane can solve the problems to a certain extent.
For example, a filter medium disclosed in CN101163533A includes a porous PTFE membrane, an air-permeable support material, and a web layer made of polymer fibers formed by an electrospinning method. Even in an environment where the proportion of ultrafine particles to be collected is large, the increase in pressure loss during use can be reduced.
On one hand, the filter material of the related art is tested to have the filtering efficiency of 99.999 percent for the particle size of 0.1-0.15 mu m. Therefore, when the proportion of particles with the particle size of more than or equal to 0.1 mu m is high, the filtering effect is good when the filter material is used; when the proportion of particles with the particle size less than or equal to 0.1 μm is high, the filtering effect is further improved. On the other hand, the above-mentioned related art uses two types of high molecular substances as an electrospinning material: 1. a water-insoluble high molecular substance; 2. a water-soluble high molecular substance. Among them, water-soluble high molecular substances are more preferred because they do not require the use of a highly volatile organic solvent in preparing a spinning solution. However, the water-soluble electrospun material has high hydrophilicity, and when a filter material prepared from the material is used in a high-humidity use environment, the problems that the filtration efficiency of pollutants is obviously reduced and the filtration efficiency is difficult to maintain for a long time easily occur.
Therefore, how to prepare a filter material which is relatively environment-friendly, has high-efficiency trapping efficiency on particles with the particle size less than or equal to 0.1 mu m and is difficult to lose efficacy is still a problem to be solved.
Disclosure of Invention
In order to prepare a filter material which is relatively environment-friendly, has high-efficiency trapping efficiency on particles with the particle size of less than or equal to 0.1 mu m and is not easy to lose efficacy, the application provides a low-resistance high-efficiency filter membrane and a manufacturing method thereof.
In a first aspect, the application provides a low-resistance high-efficiency filter membrane, which adopts the following technical scheme:
a low-resistance high-efficiency filter membrane comprises a polytetrafluoroethylene porous membrane, a fiber mesh layer and a breathable supporting material layer which are sequentially arranged, wherein the fiber mesh layer is formed by electrostatic spinning liquid containing high polymer materials through an electrostatic spinning method;
the electrostatic spinning solution is prepared from water, water-soluble high-molecular polymer and polytetrafluoroethylene emulsion; the sum of the contents of the water-soluble high molecular polymer and the polytetrafluoroethylene accounts for 25-35wt% of the total amount of the electrostatic spinning solution, and the weight ratio of the water-soluble high molecular polymer to the polytetrafluoroethylene is 3.5 (6.4-7.5);
a first non-woven fabric layer is arranged on one side, away from the fiber net layer, of the polytetrafluoroethylene porous membrane; and a second non-woven fabric layer is arranged on one side, away from the fiber net layer, of the air-permeable supporting material layer.
Through adopting above-mentioned technical scheme, have following beneficial effect:
this application sets up first non-woven fabrics layer and second non-woven fabrics layer, can show the physical and mechanical properties who improves the filter membrane for when using under high humidity environment, even if receive the form that steam influences also can keep the filter membrane longer time, porosity descends in the reduction filter membrane, does benefit to extension filter membrane life. Moreover, the first non-woven fabric layer and the second non-woven fabric layer can play a role in initially intercepting particles with larger particle sizes, and the adsorption and trapping pressure of the particles of the polytetrafluoroethylene porous membrane, the fiber net layer and the air-permeable supporting material layer is shared.
According to the preparation method, the water-soluble high-molecular polymer and the polytetrafluoroethylene emulsion are mixed to prepare the spinning solution, a high-volatility organic solvent is not needed in the spinning process, the spinning is more environment-friendly compared with the spinning using a non-water-soluble high-molecular polymer, and the fiber obtained by spinning has good physical and mechanical properties and excellent particle adsorption and trapping properties. The fibre itself that forms fibre web layer by this kind of spinning solution electrostatic spinning has the micropore, has the hole and adsorbs the entrapment effect, and polytetrafluoroethylene's high resistance also makes the fibre produce static easily to have certain electrostatic adsorption entrapment effect, these two kinds of absorption entrapment effects make the filter membrane of this application have long term efficient particle entrapment effect.
At the same time, the applicant has also surprisingly found that: when the fiber mesh layer obtained by spinning the spinning solution containing the water-soluble high-molecular polymer and the polytetrafluoroethylene is used in a high-humidity environment (the relative humidity is more than or equal to 60 percent), the fiber mesh layer can keep good porosity for a long time, and the problem that the filtration efficiency of the fiber mesh layer formed by spinning the water-soluble high-molecular polymer is reduced too fast in the high-humidity environment is effectively solved. The possible reasons for this are that, due to the good physical and mechanical properties of polytetrafluoroethylene, the prepared fiber mesh layer has a good form and is not easy to decrease in porosity due to moisture absorption, and the low surface tension and high hydrophobicity of polytetrafluoroethylene are beneficial to reducing the water vapor adsorption of the fiber and weakening the negative effect of the water vapor on the fiber mesh layer.
Further, the sum of the contents of the water-soluble high molecular polymer and the polytetrafluoroethylene accounts for 28.5wt% of the total amount of the electrospinning solution, and the weight ratio of the water-soluble high molecular polymer to the polytetrafluoroethylene is 3.5: 6.5.
The spinning solution has too high concentration and increased viscosity, which is not beneficial to electrostatic spinning; meanwhile, the water-soluble high molecular polymer accounts for a small amount, the adsorption and trapping performance of the particles is reduced, and if the water-soluble high molecular polymer accounts for too high amount, the particles are easy to lose efficacy in a high-humidity environment. The spinning performance and the particle adsorption and trapping performance of the fiber net layer are comprehensively considered, and the water-soluble high molecular polymer and the polytetrafluoroethylene are optimally controlled when the sum of the contents of the water-soluble high molecular polymer and the polytetrafluoroethylene accounts for 28.5wt% of the total amount of the electrostatic spinning solution and the weight ratio of the water-soluble high molecular polymer to the polytetrafluoroethylene is 3.5: 6.5.
Further, the water-soluble high molecular polymer is polyvinyl alcohol.
The polyvinyl alcohol and the water-soluble polyamide have better spinnability, and are suitable for spinning to obtain a fiber web layer with good particle adsorption and filtration efficiency.
Further, the first non-woven fabric layer and the second non-woven fabric layer are both PET non-woven fabrics.
The Polyester (PET) non-woven fabric has good physical and mechanical properties, poor water absorption and good strength, and is used as the first non-woven fabric layer and the second non-woven fabric layer, so that the form of the filter membrane is kept, and the problem of reduction of the filtration efficiency caused by the influence of water vapor is solved.
Further, the gram weight of the breathable support material layer is 8-50g/m2Range of PET nonwoven fabrics.
The air-permeable supporting material layer provides an attachment foundation for the fiber web layer and has a certain particle adsorption and trapping effect. And 8-50g/m2The non-woven fabric has moderate thickness and good air permeability and is suitable for being used as an air-permeable supporting material layer.
Further, the polytetrafluoroethylene porous membrane has a porosity of 75 to 90% and a pore diameter of 0.6 to 2 μm.
By adopting the technical scheme, the adsorption filtration efficiency of the filter membrane on ultrafine particles, particularly ultrafine particles with the particle size of less than 0.1 micrometer, can be improved.
In a second aspect, the present application provides a method for manufacturing a low-resistance high-efficiency filter membrane, which adopts the following technical scheme:
the production process of low resistance and high efficiency filter membrane includes the following steps:
step one, preparing an electrostatic spinning solution; the electrostatic spinning solution is prepared from water, water-soluble high-molecular polymer and polytetrafluoroethylene emulsion; the sum of the contents of the water-soluble high molecular polymer and the polytetrafluoroethylene accounts for 25-35wt% of the total amount of the electrostatic spinning solution, and the weight ratio of the water-soluble high molecular polymer to the polytetrafluoroethylene is 3.5 (6.4-7.5);
secondly, feeding the air-permeable supporting material into an electrostatic spinning machine, forming a fiber mesh layer made of high polymer materials on the air-permeable supporting material through electrostatic spinning, and drying;
step three, compounding a polytetrafluoroethylene porous membrane on the fiber net layer in a hot pressing manner;
and fourthly, compounding a first non-woven fabric layer on one side of the polytetrafluoroethylene porous membrane, which is far away from the fiber net layer, in a hot-pressing manner, and compounding a second non-woven fabric layer on one side of the air-permeable supporting material layer, which is far away from the fiber net layer, in a hot-pressing manner, so that the low-resistance high-efficiency filter membrane is obtained.
By adopting the technical scheme, the spinning solution is prepared by taking the water-soluble high molecular polymer and the polytetrafluoroethylene emulsion as raw materials, and compared with the spinning solution prepared by using the non-water-soluble high molecular polymer, the spinning solution prepared by the method does not need to use an organic solvent, and is more environment-friendly. Meanwhile, the fiber mesh layer obtained by spinning has the functions of pore adsorption and electrostatic adsorption, and has excellent particle adsorption and trapping effects. Moreover, the polytetrafluoroethylene is beneficial to keeping the form of the fiber net layer and increasing the hydrophobicity of the fiber net layer, and is beneficial to keeping the particle filtering efficiency and prolonging the service life of the filter membrane when the filter membrane is used in a high-humidity environment.
Further, in the second step, the distance between the air-permeable supporting material and the conductive plate of the electrostatic spinning machine is 10-30 cm; the electrostatic spinning voltage is 10-60kV, the environmental temperature is 20-100 ℃, and the environmental relative humidity is 15-60%.
Further, in the second step, the electrostatic spinning voltage is 16-25kV, the ambient temperature is 20-30 ℃, and the ambient relative humidity is 30-50%.
Further, in the second step, the drying temperature is 50-200 ℃, and the drying time is 3-60 min.
Drawings
FIG. 1 is a schematic diagram of the structure of the low-resistance high-efficiency filter membrane of example 1 of the present application.
FIG. 2 is a schematic diagram showing the structure of a production system for the production process of a low-resistance high-efficiency filtration membrane according to example 1 of the present application.
Description of reference numerals: 1. a first nonwoven layer; 2. a polytetrafluoroethylene porous membrane; 3. a fibrous web layer; 4. a layer of breathable support material; 5. a second nonwoven layer; 6. an electrostatic spinning machine; 61. a conductive plate; 7. an oven; 8. low-resistance high-efficiency filter membrane.
Detailed Description
The present application is described in further detail below with reference to figures 1-2 and examples.
The polyvinyl alcohol and polytetrafluoroethylene emulsions used in the following examples and comparative examples were commercially available, the polyvinyl alcohol used was PVA-1788, the polytetrafluoroethylene emulsion used was FR302 (60% solids), and in other embodiments, other types of polyvinyl alcohol and polytetrafluoroethylene emulsions were selected.
Example 1
A low-resistance high-efficiency filter membrane is shown in figure 1 and comprises a first non-woven fabric layer 1, a polytetrafluoroethylene porous membrane 2, a fiber net layer 3, an air-permeable supporting material layer 4 and a second non-woven fabric layer 5 which are sequentially arranged. The fiber web layer 3 is formed by electrospinning a solution. The first non-woven fabric layer 1 and the second non-woven fabric layer 5 both have a grammage of 30 g/m2The PET nonwoven fabric of (1); the breathable support material layer 4 has a grammage of 20g/m2Range of PET nonwoven fabrics. The polytetrafluoroethylene porous membrane 2 has a porosity of 75 to 90% and a pore diameter of 0.6 to 2 μm, and may be obtained commercially or by the home-made. In this example, the porous polytetrafluoroethylene membrane 2 had a porosity of 75%, a pore diameter of 0.6 to 2 μm, and a thickness of 35 μm.
Referring to fig. 2, the specific steps of the manufacturing method of the low-resistance high-efficiency filter membrane are as follows:
step one, dissolving PVA-1788 in water to prepare PVA aqueous solution, adding polytetrafluoroethylene emulsion FR302 (solid content 60%) and uniformly mixing, and calculating the amount of the added polytetrafluoroethylene emulsion according to the weight ratio of polyvinyl alcohol to polytetrafluoroethylene of 3.5: 6.4. And then, adding water to adjust the concentration of the spinning solution until the sum of the contents of polyvinyl alcohol and polytetrafluoroethylene accounts for 25wt% of the total amount of the electrostatic spinning solution, and ultrasonically dispersing for 20min to obtain the electrostatic spinning solution for later use.
Step two, using PET non-woven fabric (with the gram weight of 20 g/m) as the air-permeable supporting material layer 4 at the speed of 0.5-5m/min2) The PET nonwoven fabric was fed into an electrospinning machine 6 at a feeding speed of 5m/min in this example. PET non-woven fabric (gram weight is 20 g/m)2) The conductive plate 61 is parallel to the conductive plate 61, the conductive plate 61 is connected with a high-voltage power supply, and the electrostatic spinning solution box is grounded. The conductive plate 61 and PET nonwoven fabric (gram weight 20 g/m)2) The spacing is adjustable, typically 10-30cm, in this example 10 cm. Controlling electrostatic spinning voltage at 10-60kV, environment temperature at 20-100 deg.C, and relative humidity at 15-60% to make the spinning solution form and adhere to PET non-woven fabric (gram weight)Is 20g/m2) The fiber web layer 3. The process parameters of electrostatic spinning in this example are: the voltage is 60kV, the ambient temperature is 80 ℃, and the ambient relative humidity is 60%. After spinning, the PET nonwoven fabric with the fiber web layer 3 attached thereto was dried in an oven at 120 ℃ for 30 min.
And step three, hot-pressing the composite polytetrafluoroethylene porous membrane 2 on the fiber net layer 3.
Fourthly, compounding a layer of PET non-woven fabric (the gram weight is 30 g/m) on the side of the polytetrafluoroethylene porous membrane 2, which is far away from the fiber mesh layer 3 in a hot pressing way2) Forming a first nonwoven fabric layer 1 on a breathable support material layer 4 (PET nonwoven fabric, grammage 20 g/m)2) One side of the fiber net layer 3 is hot-pressed and compounded with a layer of PET non-woven fabric (the gram weight is 30 g/m)2) Forming a second non-woven fabric layer 5 to obtain the low-resistance high-efficiency filter membrane 8.
Examples 2 to 3
Examples 2 to 3 are based on example 1 and differ from example 1 in that:
in the first step of example 2, the sum of the contents of polyvinyl alcohol and polytetrafluoroethylene was 28.5wt% based on the total amount of the electrospinning solution;
in the first step of example 3, the sum of the contents of polyvinyl alcohol and polytetrafluoroethylene was 35wt% based on the total amount of the electrospinning solution.
Comparative examples 1 to 2
Comparative examples 1-2 are based on example 1 and differ from example 1 in that:
in the first step of comparative example 1, the sum of the contents of polyvinyl alcohol and polytetrafluoroethylene accounts for 20wt% of the total amount of the electrospinning solution;
in the first step of comparative example 2, the sum of the contents of polyvinyl alcohol and polytetrafluoroethylene was 40wt% based on the total amount of the electrospinning solution.
And (3) detecting the filtering efficiency:
reference is made to High efficiency air filters (EPA, HEPA and ULPA) Part3: Testing flat sheet filter media (EN 1822-3-2009) [ translation: high efficiency air filters (EPA, HEPA and ULPA) part3: testing flat filter media (EN 1822-3-2009)]The filtration efficiency of the low-resistance and high-efficiency filter membranes prepared in the above examples and comparative examples was measured,record the Most Penetrating Particle Size (MPPS) and the most penetrating particle size filtration efficiency (E)MPPS). The specific detection conditions are as follows: the test environment temperature is 25 + -5 deg.C, the test environment relative humidity is 50 + -15%, the aerosol type is diisooctyl sebacate (DEHS) aerosol, the gas flow is 32L/min, and the test area is 100cm2。
A. Initial filtration efficiency experimental group
The low-resistance and high-efficiency filtration membranes obtained in examples 1 to 3 and comparative examples 1 to 2 were collected as samples, and the test was carried out according to the method described above. The test results are reported in table 1.
TABLE 1 initial filtration efficiency test results of examples 1-3 and comparative examples 1-2
B. High-humidity filtration efficiency experiment set
The low-resistance and high-efficiency filter membranes prepared in examples 1 to 3 and comparative examples 1 to 2 were collected as samples and divided into two groups, and the samples were humidified in a constant temperature and humidity cabinet for 1 hour. After the treatment, the filtration efficiency of the sample was measured according to the method described above, and the Most Penetrating Particle Size (MPPS) and the most penetrating particle size filtration efficiency (E) of the sample after treatment under the treatment conditions were recordedMPPS) The results are reported in Table 2.
TABLE 2 table of the results of the high humidity filtration efficiency test of examples 1 to 3 and comparative examples 1 to 2
The data in tables 1 and 2 show that: the filtration membranes prepared in examples 1-3 all had high filtration efficiency, and the most permeable particle size filtration efficiency was 99.9995% or more when no sample was treated. Furthermore, the filtration efficiency of the filtration membrane obtained in example 1-3 was maintained at 99.9995% or more, with only a small decrease in the most permeable particle size after treatment in a high humidity environment at room temperature (25 ℃ C., relative humidity 75%).
Meanwhile, the data of comparative example 1 and comparative examples 1 to 2 can find that: the concentration of the electrostatic spinning solution is too low or too high, which is not beneficial to improving the filtration efficiency of the filter membrane. Without treatment in a high humidity environment, the filters of example 1 and comparative examples 1-2 had comparable filtration efficiencies at initial most-penetrable particle sizes. However, the initial most penetrable particle size filtration efficiency of comparative example 1-2 was significantly reduced after the treatment in the high humidity environment. Therefore, the content sum of the polyvinyl alcohol and the polytetrafluoroethylene accounts for 25-35% of the total weight of the electrostatic spinning solution, so that a filter membrane with good filtering efficiency in a high-humidity environment can be prepared, and the service life of the filter membrane is longer because the filtering efficiency of the filter membrane is not obviously reduced.
Examples 4 to 5
Examples 4 to 5 are based on example 2 and differ from example 2 in that:
in the first step of example 4, the weight ratio of polyvinyl alcohol to polytetrafluoroethylene is 3.5: 6.5;
in step two of example 5, the weight ratio of polyvinyl alcohol to polytetrafluoroethylene was 3.5: 7.5.
Comparative examples 3 to 4
Comparative examples 3 to 4 are based on example 4 and differ from example 4 in that:
in step one of comparative example 3, the weight ratio of polyvinyl alcohol to polytetrafluoroethylene was 3.5: 6;
in step one of comparative example 4, the weight ratio of polyvinyl alcohol to polytetrafluoroethylene was 3.5: 8.
The filtration efficiency of the filters of examples 4 to 5 and comparative examples 3 to 4 without high humidity treatment and the filtration efficiency after high humidity treatment were measured by the same test method as example 2. The test results are reported in tables 3 and 4.
TABLE 3 initial filtration efficiency test results of examples 2/4-5 and comparative examples 3-4
TABLE 4 table of the results of the high humidity filtration efficiency test of examples 2/4-5 and comparative examples 3-4
The data in tables 3 and 4 show that: adjusting the weight ratio of polyvinyl alcohol to polytetrafluoroethylene affects the filtration performance of the resulting filter membrane, specifically increasing polytetrafluoroethylene is beneficial for reducing the most penetrable particle size, probably because of its high resistance properties making it easy to carry static electricity, and thus being able to adsorb particles of smaller size, thus manifesting as an increase in the ratio of polytetrafluoroethylene to the least penetrable particle size. From experimental data, it is found that when the weight ratio of polyvinyl alcohol to polytetrafluoroethylene is in the range of 3.5 (6.5-7.5), the filtration efficiency is in a preferable range regardless of the most penetrable particle size or the most penetrable particle size. When the weight ratio of the polyvinyl alcohol to the polytetrafluoroethylene is more than 3.5:6.4, although the filtering efficiency of the most penetrable particle size is still acceptable, the most penetrable particle size is obviously increased; when the weight ratio of the polyvinyl alcohol to the polytetrafluoroethylene is less than 3.5:7.5, although the most penetrable particle size is small, the most penetrable particle size is significantly reduced in filtration efficiency. In general, the weight ratio of the polyvinyl alcohol to the polytetrafluoroethylene is preferably 3.5 (6.5-7.5); when the weight ratio of polyvinyl alcohol to polytetrafluoroethylene is 3.5:6.5, the most penetrable particle size is small and sufficiently high filtering efficiency of the most penetrable particle size can be maintained.
After the treatment in the high humidity environment, the most penetrable particle size is increased, which may be caused by the fact that the high humidity environment increases the hydrophilicity of the filter membrane and weakens the filtering effect of electrostatic adsorption on the fine particle size, but the most penetrable particle size filtering efficiency of the filter membrane is reduced on the whole, but still maintained at a more excellent level.
Examples 6 to 9
Examples 6 to 9 are based on example 4 and differ from example 4 in that: the specifications of the first nonwoven fabric layer, the second nonwoven fabric layer, the air-permeable support material layer, and the porous polytetrafluoroethylene membrane were selected to be different, as shown in table 5.
TABLE 5 specification of materials for each layer of examples 6-9
The filtration efficiency of the filtration membranes of examples 6-9 without high humidity environment treatment and the filtration efficiency after high humidity environment treatment were measured by the same test method as example 4. The test results are shown in tables 6 and 7.
TABLE 6 initial filtration efficiency test results of examples 4/6-9
TABLE 7 table of the results of the high humidity filtration efficiency test of examples 4/6-9
The data in tables 6 and 7 show that: the materials and the thicknesses of the first non-woven fabric layer and the second non-woven fabric layer are changed, and the overall filtering effect of the filter membrane is not obviously influenced. Meanwhile, as can be seen from experimental data, the gram weight is 8-50g/m2The PET non-woven fabrics with different specifications in the range can be used as the air-permeable supporting material layer, and the polytetrafluoroethylene porous membrane can obtain better filtering effect when the porosity is in the range of 75-90% and the pore diameter is 0.6-2 mu m.
Examples 10 to 13
Examples 10 to 13 are based on example 4 and differ from example 4 in that: the process parameters of the second step are different, and are specifically shown in Table 8.
TABLE 8 Process parameter Table for examples 4/10-13
The filtration efficiency of the filtration membranes of examples 10-13 without high humidity treatment and the filtration efficiency after high humidity treatment were measured by the same method as in example 4. The test results are shown in tables 9 and 10.
TABLE 9 initial filtration efficiency test results of examples 4/10-13
TABLE 10 test results of high humidity filtration efficiency for examples 4/10-13
As can be seen from the data in tables 9 and 10: the electrostatic spinning process conditions are adjusted in a small range, the performance of the prepared filter membrane is not obviously influenced, and the most penetrable particle size of the prepared filter membrane have small-amplitude change in filtration efficiency. Therefore, when electrostatic spinning is carried out, the electrostatic spinning voltage is controlled to be 10-60kV, the environmental temperature is controlled to be 20-100 ℃, and the environmental relative humidity is controlled to be 15-60%. From the experimental results, the filters of examples 11-12 had small most penetrable particle size and higher most penetrable particle size filtration efficiency, and thus the electrospinning conditions were preferably selected to have an electrospinning voltage of 16-25kV, an ambient temperature of 20-30 ℃ and an ambient relative humidity of 30-50%.
The drying aims to reduce the water carrying rate, facilitate the subsequent hot-pressing of the polytetrafluoroethylene porous membrane and the non-woven fabric layer, and the specific drying temperature and drying time can be adjusted according to the actual conditions.
The present embodiment is only for explaining the present application, and it is not limited to the present application, and those skilled in the art can make modifications of the present embodiment without inventive contribution as needed after reading the present specification, but all of them are protected by patent law within the scope of the claims of the present application.
Claims (10)
1. The low-resistance high-efficiency filter membrane comprises a polytetrafluoroethylene porous membrane (2), a fiber net layer (3) and a breathable supporting material layer (4) which are sequentially arranged, wherein the fiber net layer (3) is formed by an electrostatic spinning solution containing high polymer materials through an electrostatic spinning method, and the low-resistance high-efficiency filter membrane is characterized in that:
the electrostatic spinning solution is prepared from water, water-soluble high-molecular polymer and polytetrafluoroethylene emulsion; the sum of the contents of the water-soluble high molecular polymer and the polytetrafluoroethylene accounts for 25-35wt% of the total amount of the electrostatic spinning solution, and the weight ratio of the water-soluble high molecular polymer to the polytetrafluoroethylene is 3.5 (6.4-7.5);
a first non-woven fabric layer (1) is arranged on one side, away from the fiber net layer (3), of the polytetrafluoroethylene porous membrane (2); and a second non-woven fabric layer (5) is arranged on one side, away from the fiber net layer (3), of the air-permeable supporting material layer (4).
2. The low resistance, high efficiency filter membrane of claim 1, wherein: the sum of the contents of the water-soluble high molecular polymer and the polytetrafluoroethylene accounts for 28.5wt% of the total amount of the electrostatic spinning solution, and the weight ratio of the water-soluble high molecular polymer to the polytetrafluoroethylene is 3.5: 6.5.
3. The low resistance, high efficiency filter membrane of claim 2, wherein: the water-soluble high molecular polymer is polyvinyl alcohol.
4. The low resistance, high efficiency filter membrane of claim 1, wherein: the first non-woven fabric layer (1) and the second non-woven fabric layer (5) are both PET non-woven fabrics.
5. The low resistance, high efficiency filter membrane according to any one of claims 1 to 4 wherein: the gram weight of the breathable support material layer (4) is 8-50g/m2Range of PET nonwoven fabrics.
6. The low resistance, high efficiency filter membrane according to any one of claims 1 to 4 wherein: the porosity of the polytetrafluoroethylene porous membrane (2) is 75-90%, and the pore diameter is 0.6-2 μm.
7. The method for manufacturing the low-resistance high-efficiency filter membrane is characterized by comprising the following steps of:
step one, preparing an electrostatic spinning solution; the electrostatic spinning solution is prepared from water, water-soluble high-molecular polymer and polytetrafluoroethylene emulsion; the sum of the contents of the water-soluble high molecular polymer and the polytetrafluoroethylene accounts for 25-35wt% of the total amount of the electrostatic spinning solution, and the weight ratio of the water-soluble high molecular polymer to the polytetrafluoroethylene is 3.5 (6.4-7.5);
secondly, feeding the air-permeable supporting material into an electrostatic spinning machine (6), forming a fiber mesh layer (3) made of high polymer material on the air-permeable supporting material through electrostatic spinning, and drying;
thirdly, compounding a polytetrafluoroethylene porous membrane (2) on the fiber net layer (3) in a hot pressing manner;
and fourthly, compounding a first non-woven fabric layer (1) on one side of the polytetrafluoroethylene porous membrane (2) away from the fiber net layer (3) in a hot-pressing mode, and compounding a second non-woven fabric layer (5) on one side of the air-permeable supporting material layer (4) away from the fiber net layer (3) in a hot-pressing mode to obtain the low-resistance high-efficiency filter membrane (8).
8. The method for manufacturing a low-resistance high-efficiency filter membrane according to claim 7, wherein: in the second step, the distance between the air-permeable supporting material and the conductive plate (61) of the electrostatic spinning machine (6) is 10-30 cm; the electrostatic spinning voltage is 10-60kV, the environmental temperature is 20-100 ℃, and the environmental relative humidity is 15-60%.
9. The method for manufacturing a low-resistance high-efficiency filter membrane according to claim 8, wherein: in the second step, the electrostatic spinning voltage is 16-25kV, the environmental temperature is 20-30 ℃, and the environmental relative humidity is 30-50%.
10. The method for manufacturing a low-resistance high-efficiency filter membrane according to claim 7, wherein: in the second step, the drying temperature is 50-200 ℃, and the drying time is 3-60 min.
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| CN101163533A (en) * | 2005-04-26 | 2008-04-16 | 日东电工株式会社 | Filter medium, process for producing the same, method of use thereof, and filter unit |
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| CN101163533A (en) * | 2005-04-26 | 2008-04-16 | 日东电工株式会社 | Filter medium, process for producing the same, method of use thereof, and filter unit |
| CN103990320A (en) * | 2013-02-16 | 2014-08-20 | 东丽纤维研究所（中国）有限公司 | Composite filtering material, and production method and application thereof |
| CN104998558A (en) * | 2014-04-22 | 2015-10-28 | 成都百途医药科技有限公司 | Production method of super-hydrophobic polytetrafluoroethylene membrane |
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