CN115364703A - Bi-directional simultaneous stretching polytetrafluoroethylene microporous membrane and preparation method thereof - Google Patents
Bi-directional simultaneous stretching polytetrafluoroethylene microporous membrane and preparation method thereof Download PDFInfo
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- CN115364703A CN115364703A CN202210661151.6A CN202210661151A CN115364703A CN 115364703 A CN115364703 A CN 115364703A CN 202210661151 A CN202210661151 A CN 202210661151A CN 115364703 A CN115364703 A CN 115364703A
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- stretching
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- temperature
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- 229920001343 polytetrafluoroethylene Polymers 0.000 title claims abstract description 55
- 239000004810 polytetrafluoroethylene Substances 0.000 title claims abstract description 55
- -1 polytetrafluoroethylene Polymers 0.000 title claims abstract description 20
- 239000012982 microporous membrane Substances 0.000 title claims abstract description 16
- 238000002360 preparation method Methods 0.000 title claims abstract description 10
- 239000002904 solvent Substances 0.000 claims abstract description 25
- 239000012528 membrane Substances 0.000 claims abstract description 19
- 238000000034 method Methods 0.000 claims abstract description 18
- 239000002994 raw material Substances 0.000 claims abstract description 16
- 239000011347 resin Substances 0.000 claims abstract description 9
- 229920005989 resin Polymers 0.000 claims abstract description 9
- 238000003490 calendering Methods 0.000 claims abstract description 8
- 238000001035 drying Methods 0.000 claims abstract description 8
- 238000002156 mixing Methods 0.000 claims abstract description 8
- 238000003860 storage Methods 0.000 claims abstract description 8
- 238000005245 sintering Methods 0.000 claims abstract description 4
- 238000005507 spraying Methods 0.000 claims description 7
- 238000009826 distribution Methods 0.000 claims description 6
- 239000000463 material Substances 0.000 abstract description 11
- 238000005238 degreasing Methods 0.000 description 6
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 4
- 239000000428 dust Substances 0.000 description 4
- 238000001914 filtration Methods 0.000 description 4
- 239000003546 flue gas Substances 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- 229910000831 Steel Inorganic materials 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 2
- 239000004568 cement Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000010959 steel Substances 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000002457 bidirectional effect Effects 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 239000008358 core component Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- 239000000835 fiber Substances 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000005272 metallurgy Methods 0.000 description 1
- 230000035699 permeability Effects 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 238000002407 reforming Methods 0.000 description 1
- 239000000779 smoke Substances 0.000 description 1
Classifications
-
- 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
- B01D67/0023—Organic membrane manufacture by inducing porosity into non porous precursor membranes
- B01D67/0025—Organic membrane manufacture by inducing porosity into non porous precursor membranes by mechanical treatment, e.g. pore-stretching
- B01D67/0027—Organic membrane manufacture by inducing porosity into non porous precursor membranes by mechanical treatment, e.g. pore-stretching by stretching
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2323/00—Details relating to membrane preparation
- B01D2323/08—Specific temperatures applied
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2323/00—Details relating to membrane preparation
- B01D2323/26—Spraying processes
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2323/00—Details relating to membrane preparation
- B01D2323/50—Control of the membrane preparation process
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
- Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
- Y02A50/2351—Atmospheric particulate matter [PM], e.g. carbon smoke microparticles, smog, aerosol particles, dust
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Shaping By String And By Release Of Stress In Plastics And The Like (AREA)
- Manufacture Of Porous Articles, And Recovery And Treatment Of Waste Products (AREA)
Abstract
The invention discloses a polytetrafluoroethylene microporous membrane stretched in two directions simultaneously and a preparation method thereof, belonging to the field of membrane-covered filter materials. A preparation method of a polytetrafluoroethylene microporous membrane comprises the following steps: mixing PTFE resin and M-type solvent oil by a V-type mixer; then placing the mixed raw materials in a drying room with the temperature of 50 ℃ for storage for more than 12h to obtain mixed raw materials; then, calendering by a prepress and a calender to obtain a PTFE blank film with controllable thickness and width; removing the M-type solvent oil in the PTFE blank film, wherein the blank film is not stretched in the process; and (3) placing the blank membrane subjected to M-type solvent oil removal in a transverse stretching machine for transverse and longitudinal simultaneous biaxial stretching, and sintering and curing to obtain the PTFE microporous membrane.
Description
Technical Field
The invention relates to the field of membrane-covered filter materials, in particular to a polytetrafluoroethylene microporous membrane stretched in two directions simultaneously and a preparation method thereof.
Background
Environmental pollution caused by human activities is increasingly emphasized in countries in the world, and more severe requirements are put forward for industrial smoke emission in countries in the world. The dust emission in the industries of cement, metallurgy, electric power, steel and the like is large, and the method is always the key point of the flue gas treatment in the China industry. Bag-type dust removal becomes a main mode for treating industrial flue gas at home and abroad, and the core components of the bag-type dust removal are as follows: the performance and quality of the filter bag are directly related to industrial flue gas emission indexes. The traditional bag type dust removal uses filter materials without membrane, the filtration mechanism is 'deep filtration', but the filtration precision can not meet the requirement due to larger pores among fibers.
In the seventies of the last century, a layer of microporous polytetrafluoroethylene film with a net structure is coated on a common filter material, the filter effect of the filter material is better than that of the common filter material, and the application amount of the membrane-coated filter material in heavy pollution industries such as cement, steel and the like is increased sharply due to the strict requirement of national policies on the filter precision of industrial flue gas. However, the filtration precision of the membrane-coated filter material depends on the performance of the polytetrafluoroethylene membrane material, and the requirement of the polytetrafluoroethylene microporous membrane in the preparation process is high.
At the present stage, the polytetrafluoroethylene microporous membrane is mainly prepared by longitudinally stretching and transversely stretching to form a fibrous microporous structure, but in the process of the stage, the apparent quality of a finished product membrane is uneven due to insufficient transmission of stretching force in the stretching process of a polytetrafluoroethylene blank membrane, and the subsequent use performance is seriously influenced.
Therefore, the invention avoids the phenomena of insufficient transmission of tensile force and the like by simultaneously stretching in the transverse direction and the longitudinal direction.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a polytetrafluoroethylene microporous membrane stretched in two directions simultaneously and a preparation method thereof.
The purpose of the invention can be realized by the following technical scheme:
a preparation method of a polytetrafluoroethylene microporous membrane comprises the following steps:
mixing PTFE resin and M-type solvent oil by a V-type mixer; then placing the mixed raw materials in a drying room with the temperature of 50 ℃ for storage for more than 12h to obtain mixed raw materials; then, calendering by a prepress and a calender to obtain a PTFE blank film with controllable thickness and width;
removing the M-type solvent oil in the PTFE blank film, wherein the blank film is not stretched in the process;
and (3) placing the blank membrane subjected to M-type solvent oil removal in a transverse stretching machine for transverse and longitudinal simultaneous biaxial stretching, and sintering and curing to obtain the PTFE microporous membrane.
Optionally, the solvent oil is added by spraying at regular time and quantity.
Optionally, the temperature environment of the biaxial stretching is configured to:
the temperature distribution in the stretching zone is: the stretching temperature is 300 ℃ in the stretching 1 region, 310 ℃ in the stretching 2 region, 320 ℃ in the stretching 3 region, and the curing temperature is 330 ℃ and 340 ℃ respectively.
Optionally, the stretching speed of the biaxial stretching is 25m/min.
Optionally, the temperature environment for removing the M-type solvent oil in the PTFE green film is 200 ℃.
On the other hand, the invention also provides the polytetrafluoroethylene microporous membrane prepared by the method.
The invention has the beneficial effects that:
(1) The invention changes the unidirectional stretching of a transverse stretching area into bidirectional stretching by reforming the inside of the existing transverse stretcher, namely the transverse stretching and the longitudinal stretching are carried out in a stretching link, the transverse stretching and the longitudinal stretching are simultaneously carried out, and the speed difference of different stretching areas is realized by gears with different sizes, so that the longitudinal stretching and the transverse stretching are simultaneously carried out;
(2) The existing preparation process flow and heating area are saved, and the energy consumption is reduced;
(3) The precise control of the width of the film is realized;
Detailed Description
The technical solutions in the embodiments of the present invention are clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The experimental steps are as follows:
(1) Preparing a blank film: mixing PTFE resin and M-type solvent oil in a certain proportion by a V-shaped mixer (the solvent oil is added in a timed and quantitative spraying manner, so as to ensure that the PTFE resin is uniformly mixed); then placing the mixed raw materials in a drying room with the temperature of 50 ℃ for storage for more than 12h to obtain mixed raw materials; then, calendering by a prepress and a calender to obtain a PTFE blank film with controllable thickness and width;
(2) Degreasing: removing solvent oil from the obtained PTFE blank film at the temperature of 200 ℃, wherein the blank film is not stretched in the process; (blank film and degreasing process are carried out continuously)
(3) Placing the blank membrane subjected to oil removal in a transverse stretching machine to perform transverse and longitudinal simultaneous biaxial stretching, and sintering and curing to obtain a PTFE microporous membrane;
and testing the performance to obtain a finished film with the porosity of more than 90%, the air permeability of 140mm/s and the width of 2.0-2.6 m.
Example 1:
(1) Preparing a blank film: adding 28% of M-type solvent oil into PTFE resin through a V-type mixer in a mode of adding and spraying at the same time, and mixing for 25min; then placing the mixed raw materials in a drying room with the temperature of 50 ℃ for storage for more than 12h to obtain mixed raw materials; then, calendering by a prepress and a calender to obtain a PTFE blank film with controllable thickness and width;
(2) Degreasing: removing solvent oil from the obtained PTFE blank film at the temperature of 200 ℃, wherein the blank film is not stretched any more in the process;
(3) Placing the blank film subjected to oil removal in a transverse stretching machine for transverse and longitudinal simultaneous stretching, wherein the temperature distribution of a stretching area is as follows: stretching the mixture in a stretching 1 area at 300 ℃, a stretching 2 area at 310 ℃, a stretching 3 area at 320 ℃, curing area at 330 ℃ and 340 ℃ respectively, and stretching speed at 25m/min; obtaining a finished PTFE membrane;
example 2:
(1) Preparing a blank film: adding 29% of M-type solvent oil into PTFE resin through a V-type mixer in a mode of adding and spraying at the same time, and mixing for 25min; then placing the mixed raw materials in a drying room with the temperature of 50 ℃ for storage for more than 12h to obtain mixed raw materials; then, calendering by a prepress and a calender to obtain a PTFE blank film with controllable thickness and width;
(2) Degreasing: removing solvent oil from the obtained PTFE blank film at the temperature of 200 ℃, wherein the blank film is not stretched any more in the process;
(3) Placing the blank film subjected to oil removal in a transverse stretching machine for transverse and longitudinal simultaneous stretching, wherein the temperature distribution of a stretching area is as follows: stretching the mixture in a stretching 1 area at 300 ℃, a stretching 2 area at 310 ℃, a stretching 3 area at 320 ℃, curing area at 330 ℃ and 340 ℃ respectively, and stretching speed at 25m/min; obtaining a finished PTFE membrane;
example 3:
(1) Preparing a blank film: adding 30% of M-type solvent oil into PTFE resin through a V-type mixer in a mode of adding and spraying at the same time, and mixing for 25min; then placing the mixed raw materials in a drying room with the temperature of 50 ℃ for storage for more than 12h to obtain mixed raw materials; then, calendering by a prepress and a calender to obtain a PTFE blank film with controllable thickness and width;
(2) Degreasing: removing solvent oil from the obtained PTFE blank film at the temperature of 200 ℃, wherein the blank film is not stretched any more in the process;
(3) Placing the blank film subjected to oil removal in a transverse stretching machine for transverse and longitudinal simultaneous stretching, wherein the temperature distribution of a stretching area is as follows: stretching the mixture in a stretching 1 area at 300 ℃, a stretching 2 area at 310 ℃, a stretching 3 area at 320 ℃, curing area at 330 ℃ and 340 ℃ respectively, and stretching speed at 25m/min; obtaining a finished PTFE membrane;
comparative example 1:
(1) Preparing a blank film: adding 29% of M-type solvent oil into PTFE resin through a V-type mixer in a mode of adding and spraying at the same time, and mixing for 25min; then placing the mixed raw materials in a drying room with the temperature of 50 ℃ for storage for more than 12h to obtain mixed raw materials; then, calendering by a prepress and a calender to obtain a PTFE blank film with controllable thickness and width;
(2) Degreasing and longitudinally drawing: removing solvent oil from the obtained PTFE blank film at the temperature of 200 ℃, and then performing longitudinal stretching, wherein the temperature of a longitudinal stretching area is set to be 260 ℃;
(3) Placing the longitudinally stretched blank film on a transverse stretching machine for transverse stretching, wherein the temperature distribution of a stretching area is as follows: stretching the mixture in a stretching 1 area at 300 ℃, a stretching 2 area at 310 ℃, a stretching 3 area at 320 ℃, curing area at 330 ℃ and 340 ℃ respectively, and stretching speed at 25m/min; obtaining a finished PTFE membrane;
and (4) performance testing:
compared with the embodiment and the performances of the proportion, the overall uniformity of the finished film can be evaluated through the CV value, the CV value is low, the explanation deviation is small, the uniformity is overall better, and the overall performance is better.
In the description herein, references to the description of "one embodiment," "an example," "a specific example" or the like are intended to mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
Claims (7)
1. A preparation method of a polytetrafluoroethylene microporous membrane is characterized by comprising the following steps:
mixing PTFE resin and M-type solvent oil by a V-type mixer; then placing the mixed raw materials in a drying room with the temperature of 50 ℃ for storage for more than 12h to obtain mixed raw materials; then, calendering by a prepress and a calender to obtain a PTFE blank film with controllable thickness and width;
removing the M-type solvent oil in the PTFE blank film, wherein the blank film is not stretched in the process;
and (3) placing the blank membrane subjected to M-type solvent oil removal in a transverse stretching machine for transverse and longitudinal simultaneous biaxial stretching, and sintering and curing to obtain the PTFE microporous membrane.
2. The method for preparing microporous polytetrafluoroethylene membrane according to claim 1, wherein the solvent oil is added by spraying at regular time and quantity in a V-shaped blender.
3. The method for preparing a polytetrafluoroethylene microporous membrane according to claim 1, wherein the temperature environment of the biaxial stretching is configured as follows:
the temperature distribution in the stretching zone is: the stretching temperature is 300 ℃ in a stretching 1 region, 310 ℃ in a stretching 2 region, 320 ℃ in a stretching 3 region, and the curing temperature is 330 ℃ and 340 ℃ respectively.
4. The method for preparing a microporous polytetrafluoroethylene membrane according to claim 1, wherein the biaxial stretching is carried out at a stretching speed of 25m/min.
5. The method for preparing microporous polytetrafluoroethylene membrane according to claim 1, wherein the solvent oil M isRatio of Example (b)28 to 30 percent.
6. The method for preparing a microporous polytetrafluoroethylene membrane according to claim 1, wherein said environment for removing M-type solvent oil from said PTFE green film is at a temperature of 200 ℃.
7. A microporous polytetrafluoroethylene membrane made by the process of any of claims 1 to 6.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210661151.6A CN115364703A (en) | 2022-06-13 | 2022-06-13 | Bi-directional simultaneous stretching polytetrafluoroethylene microporous membrane and preparation method thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210661151.6A CN115364703A (en) | 2022-06-13 | 2022-06-13 | Bi-directional simultaneous stretching polytetrafluoroethylene microporous membrane and preparation method thereof |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN115364703A true CN115364703A (en) | 2022-11-22 |
Family
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202210661151.6A Withdrawn CN115364703A (en) | 2022-06-13 | 2022-06-13 | Bi-directional simultaneous stretching polytetrafluoroethylene microporous membrane and preparation method thereof |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN115364703A (en) |
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2022
- 2022-06-13 CN CN202210661151.6A patent/CN115364703A/en not_active Withdrawn
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Application publication date: 20221122 |
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