CN119283390A - A dimensionally stable expanded polytetrafluoroethylene fiber membrane and a preparation method thereof - Google Patents
A dimensionally stable expanded polytetrafluoroethylene fiber membrane and a preparation method thereof Download PDFInfo
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Abstract
本发明公开了一种尺寸稳定型膨体聚四氟乙烯纤维膜及其制备方法，在制备膨体聚四氟乙烯纤维膜时，将聚四氟乙烯分散树脂与润滑油混合均匀后，依次经过熟化、压胚、挤出、压延、脱脂处理得到聚四氟乙烯基带，再采用新型双向拉伸工艺，对聚四氟乙烯基带依次进行首次纵向拉伸、首次高温定型处理、二次纵向拉伸、横向拉伸、沿纵向方向回缩、二次热定型处理后得到尺寸稳定型膨体聚四氟乙烯纤维膜。此新型双向拉伸工艺，能够调节聚四氟乙烯纤维膜的微观结构，使得纤维膜节点呈细条状、且沿横向方向排列，在不影响膜性能的基础上，能够有效解决纤维膜横向收缩问题，保证了膜尺寸的稳定。
The present invention discloses a dimensionally stable expanded polytetrafluoroethylene fiber membrane and a preparation method thereof. When preparing the expanded polytetrafluoroethylene fiber membrane, after the polytetrafluoroethylene dispersion resin and lubricating oil are evenly mixed, the polytetrafluoroethylene-based tape is obtained by aging, pressing, extruding, calendering, and degreasing in sequence, and then a novel biaxial stretching process is adopted to sequentially perform the first longitudinal stretching, the first high-temperature shaping treatment, the second longitudinal stretching, the transverse stretching, the longitudinal shrinkage, and the second heat shaping treatment on the polytetrafluoroethylene-based tape to obtain the dimensionally stable expanded polytetrafluoroethylene fiber membrane. This novel biaxial stretching process can adjust the microstructure of the polytetrafluoroethylene fiber membrane, so that the fiber membrane nodes are in the shape of thin strips and arranged in the transverse direction. On the basis of not affecting the membrane performance, it can effectively solve the transverse shrinkage problem of the fiber membrane and ensure the stability of the membrane size.
Description
Technical Field
The invention relates to the field of membrane preparation, in particular to a size-stable expanded polytetrafluoroethylene fiber membrane and a preparation method thereof.
Background
Expanded PTFE is one kind of microporous material prepared with dispersed PTFE resin and through stretching and other special processing process, and has the features of no toxicity, no carcinogen, no sensitization, etc. The expanded polytetrafluoroethylene membrane is widely used as a novel polymer material in the aspects of medical treatment, separation filtration, sealing, electrical insulation, field products and the like. The expanded polytetrafluoroethylene film has a three-dimensional net structure, which is formed by connecting a plurality of microfibers, and the connection point of the fiber bundles is a node.
The existing preparation process of the expanded polytetrafluoroethylene fiber membrane comprises the steps of curing, compacting, extruding, calendaring, degreasing, longitudinal stretching, transverse stretching and heat setting. The invention patent with the application publication number of CN 116834346A discloses an expanded polytetrafluoroethylene film, and the preparation method comprises premixing, mould pressing, extrusion, double-roll calendaring, biaxial stretching and hot pressing. However, the structure of the film produced by this process is a network structure formed by fibers and nodes alternately, and the nodes are mostly circular or elliptical. Because the polytetrafluoroethylene polymer material has higher cohesive force, the stretched film, especially the film stretched transversely, is easy to retract in the transverse direction, and the size of the film hole is difficult to maintain. To solve this problem, it is generally necessary to increase the heat setting temperature or to heat press the prepared membrane during the preparation, but these methods result in difficulty in effective control of the membrane pore diameter, reduced membrane permeability, and negative effects on the performance of the expanded polytetrafluoroethylene fiber membrane.
Disclosure of Invention
In order to solve the problems, in a first aspect, the invention provides a preparation method of a dimensionally stable expanded polytetrafluoroethylene fiber membrane, by which the problem of transverse shrinkage of the fiber membrane can be effectively solved, and the dimensional stability of the membrane is ensured.
The technical scheme for solving the problems is as follows:
A preparation method of a size-stable expanded polytetrafluoroethylene fiber membrane comprises the following steps:
S1, uniformly mixing polytetrafluoroethylene dispersion resin and lubricating oil according to a proportion, curing, and sequentially performing compaction, extrusion, calendaring and degreasing treatment to obtain a polytetrafluoroethylene baseband;
s2, longitudinally stretching the polytetrafluoroethylene base band for the first time to obtain a polytetrafluoroethylene first stretching band;
S3, performing first high-temperature setting treatment on the polytetrafluoroethylene first stretching belt;
S4, carrying out secondary longitudinal stretching on the polytetrafluoroethylene first stretching belt subjected to the primary high-temperature setting treatment to obtain a polytetrafluoroethylene second stretching belt;
s5, transversely stretching the polytetrafluoroethylene second stretching belt to obtain a polytetrafluoroethylene fiber membrane;
S6, longitudinally heating the polytetrafluoroethylene fiber membrane to retract by 0.05-0.2 times, and secondarily heat-setting to obtain the size-stable expanded polytetrafluoroethylene fiber membrane.
According to the application, the polytetrafluoroethylene fiber membrane is longitudinally heated to retract by 0.05-0.2 times, namely, the polytetrafluoroethylene fiber membrane is longitudinally retracted to 80-95% of the polytetrafluoroethylene fiber membrane in the S5.
In the preparation method, the polytetrafluoroethylene base band is subjected to first high-temperature setting treatment after first longitudinal stretching, so that nodes formed by the fibers are softened and bonded together, and the nodes are regularly split during second longitudinal stretching, so that the pore diameter distribution of the fiber membrane is uniform. The polytetrafluoroethylene fiber membrane is longitudinally heated to retract by 0.05-0.2 times, so that the fibers and nodes in the membrane can be further retracted, and the nodes are arranged as orderly as possible. Therefore, the preparation method can effectively solve the problem of transverse shrinkage of the fiber membrane on the basis of not affecting the membrane performance, and ensures the stability of the membrane size.
Preferably, in the step S1, the mass ratio of the polytetrafluoroethylene dispersion resin to the lubricating oil is (8-12): 20-30.
Preferably, in the step S1, the curing temperature is 30 to 80 ℃ and the curing time is 10 to 24 hours.
Preferably, in the step S2, the first longitudinal stretching temperature is 200-260 ℃, and the first longitudinal stretching multiple is 2-5 times.
Preferably, in the step S3, the first high-temperature setting treatment temperature is 300-340 ℃ and the treatment time is 1-3 min.
Preferably, in the step S4, the secondary longitudinal stretching temperature is 200-260 ℃, and the secondary longitudinal stretching multiple is 2-5 times.
Preferably, in the step S5, the transverse stretching temperature is 250 to 300 ℃, and the transverse stretching multiple is 4 to 8 times.
Preferably, in the step S6, the longitudinal heating retraction temperature is 240 to 280 ℃.
Preferably, in the step S6, the secondary heat setting temperature is 330-360 ℃, and the secondary heat setting time is 1-3 min.
In a second aspect, the invention provides a dimensionally stable expanded polytetrafluoroethylene fiber membrane, wherein fiber membrane nodes are in a thin strip shape, are arranged along the transverse direction, and have good dimensional stability, and the dimensionally stable expanded polytetrafluoroethylene fiber membrane is obtained by the preparation method.
The invention has the following beneficial effects:
When the expanded polytetrafluoroethylene fiber membrane is prepared, polytetrafluoroethylene dispersion resin and lubricating oil are uniformly mixed, and then are subjected to curing, blank pressing, extrusion, calendaring and degreasing treatment in sequence to obtain a polytetrafluoroethylene base band, and then a novel biaxial stretching process is adopted to sequentially carry out first longitudinal stretching, first high-temperature shaping treatment, second longitudinal stretching, transverse stretching, retraction along the longitudinal direction and second heat shaping treatment on the polytetrafluoroethylene base band to obtain the size-stable expanded polytetrafluoroethylene fiber membrane.
Drawings
FIG. 1 is a scanning electron microscope image of an expanded polytetrafluoroethylene fiber membrane of example 3;
FIG. 2 is a scanning electron microscope image of the expanded polytetrafluoroethylene fiber membrane of comparative example 1.
Detailed Description
For the purposes of making the objects, technical solutions and advantages of the present invention more apparent, the present invention will be further described in detail with reference to the accompanying drawings and examples, it being understood that the specific examples described herein are intended to illustrate the present invention, not all the examples. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present invention without making any inventive effort, are within the scope of the present invention.
Example 1
S1, uniformly mixing polytetrafluoroethylene dispersion resin (the Eastern Mountain 204,204) with lubricating oil (aviation kerosene) according to a mass ratio of 10:20, and curing for 10 hours at 80 ℃ to obtain cured materials, wherein the cured materials are sequentially subjected to a briquetting machine, an extruder, a calender and degreasing treatment to obtain polytetrafluoroethylene base bands;
S2, longitudinally stretching the polytetrafluoroethylene base band for 2 times at 200 ℃ for the first time to obtain a polytetrafluoroethylene first stretching band;
s3, heating the polytetrafluoroethylene first stretching belt at 340 ℃ for 1min, and performing first high-temperature setting treatment;
S4, longitudinally stretching the polytetrafluoroethylene first stretching belt subjected to the first high-temperature setting treatment for 5 times at 260 ℃ to obtain a polytetrafluoroethylene second stretching belt;
S5, transversely stretching the polytetrafluoroethylene second stretching belt for 4 times at the temperature of 250 ℃ to obtain a polytetrafluoroethylene fiber membrane;
S6, heating and retracting the polytetrafluoroethylene fiber membrane at 240 ℃ along the longitudinal direction for 0.05 times, and finally performing secondary heat setting at 360 ℃ for 1min to obtain the expanded polytetrafluoroethylene fiber membrane which is named as M1.
Example 2
S1, uniformly mixing polytetrafluoroethylene dispersion resin (the Eastern Mountain 216,216) and lubricating oil (aviation kerosene) according to a mass ratio of 10:30, curing for 24 hours at a temperature of 30 ℃ to obtain cured materials, and sequentially carrying out briquetting machine, extruder, calender and degreasing treatment on the cured materials to obtain polytetrafluoroethylene base band;
S2, longitudinally stretching the polytetrafluoroethylene base band for 5 times at 260 ℃ for the first time to obtain a polytetrafluoroethylene first stretching band;
s3, heating the polytetrafluoroethylene first stretching belt at a high temperature of 300 ℃ for 3min, and performing first high-temperature setting treatment;
S4, longitudinally stretching the polytetrafluoroethylene first stretching belt subjected to the first high-temperature setting treatment for 2 times at 200 ℃ to obtain a polytetrafluoroethylene second stretching belt;
s5, transversely stretching the polytetrafluoroethylene second stretching belt for 8 times at 300 ℃ to obtain a polytetrafluoroethylene fiber membrane;
S6, heating and retracting the polytetrafluoroethylene fiber membrane at 280 ℃ along the longitudinal direction for 0.2 times, and finally performing secondary heat setting at 330 ℃ for 3min to obtain the expanded polytetrafluoroethylene fiber membrane which is named as M2.
Example 3
S1, uniformly mixing polytetrafluoroethylene dispersion resin (the Eastern Mountain 216,216) and lubricating oil (aviation kerosene) according to a mass ratio of 10:25, curing for 18 hours at 50 ℃ to obtain cured materials, and sequentially carrying out briquetting, extruding, calendaring and degreasing treatment on the cured materials to obtain polytetrafluoroethylene base bands;
s2, longitudinally stretching the polytetrafluoroethylene base band for 3 times at 240 ℃ for the first time to obtain a polytetrafluoroethylene first stretching band;
S3, heating the polytetrafluoroethylene first stretching belt at a high temperature of 320 ℃ for 2min, and performing first high-temperature setting treatment;
S4, longitudinally stretching the polytetrafluoroethylene first stretching belt subjected to the first high-temperature setting treatment for 3 times at 240 ℃ for the second time to obtain a polytetrafluoroethylene second stretching belt;
S5, transversely stretching the polytetrafluoroethylene second stretching belt for 6 times at 290 ℃ to obtain a polytetrafluoroethylene fiber membrane;
S6, heating and retracting the polytetrafluoroethylene fiber membrane at 260 ℃ along the longitudinal direction for 0.1 time, and finally performing secondary heat setting at 340 ℃ for 1.5min to obtain the expanded polytetrafluoroethylene fiber membrane, which is named as M3.
Example 4
S1, uniformly mixing polytetrafluoroethylene dispersion resin (DuPont 601) and lubricating oil (aviation kerosene) according to a mass ratio of 10:22, curing for 15 hours at a temperature of 60 ℃ to obtain cured materials, and sequentially carrying out briquetting machine, extruder, calender and degreasing treatment on the cured materials to obtain polytetrafluoroethylene base band;
S2, longitudinally stretching the polytetrafluoroethylene base band for 2 times at 200 ℃ for the first time to obtain a polytetrafluoroethylene first stretching band;
s3, heating the polytetrafluoroethylene first stretching belt at a high temperature of 330 ℃ for 1.5min, and performing first high-temperature setting treatment;
s4, longitudinally stretching the polytetrafluoroethylene first stretching belt subjected to the first high-temperature setting treatment for 4 times at the temperature of 250 ℃ to obtain a polytetrafluoroethylene second stretching belt;
S5, transversely stretching the polytetrafluoroethylene second stretching belt for 4 times at the temperature of 250 ℃ to obtain a polytetrafluoroethylene fiber membrane;
S6, heating and retracting the polytetrafluoroethylene fiber membrane at 240 ℃ along the longitudinal direction for 0.15 times, and finally performing secondary heat setting at 350 ℃ for 1min to obtain the expanded polytetrafluoroethylene fiber membrane, which is named as M4.
Comparative example 1
S1, uniformly mixing polytetrafluoroethylene dispersion resin (the Eastern Mountain 216,216) and lubricating oil (aviation kerosene) according to a mass ratio of 10:25, curing for 18 hours at 50 ℃ to obtain cured materials, and sequentially carrying out briquetting, extruding, calendaring and degreasing treatment on the cured materials to obtain polytetrafluoroethylene base bands;
S2, longitudinally stretching the polytetrafluoroethylene base band for 9 times at 240 ℃ to obtain a polytetrafluoroethylene first stretching band;
s3, transversely stretching the polytetrafluoroethylene first stretching belt for 6 times at 290 ℃ to obtain a polytetrafluoroethylene fiber membrane;
S4, performing heat setting on the polytetrafluoroethylene fiber membrane at 340 ℃ for 1.5min to obtain the expanded polytetrafluoroethylene fiber membrane, which is named as M0.
The expanded polytetrafluoroethylene fiber films obtained in examples 1 to 4 and comparative example 1 were tested by slitting the prepared samples into rolls having a width of 50.+ -. 0.1cm and a length of 100.+ -. 0.1m, storing the rolls at 30 ℃ and testing the width of the samples every 10 days, and the test results are shown in the following table.
TABLE 1 sample lateral Width test data sheet
| Sample numbering | Gram weight (g) | 10D transverse width (cm) | 20D transverse width (cm) | 30D transverse width (cm) |
| M1 | 4~6 | 50±0.1 | 50±0.1 | 50±0.1 |
| M2 | 4~6 | 50±0.1 | 50±0.1 | 50±0.1 |
| M3 | 7~8 | 50±0.1 | 50±0.1 | 50±0.1 |
| M4 | 10~12 | 50±0.1 | 50±0.1 | 50±0.1 |
| M0 | 7~8 | 49±0.1 | 48.1±0.1 | 47.2±0.1 |
As can be seen from Table 1, the expanded polytetrafluoroethylene fiber membranes prepared in examples 1 to 4 had no change in lateral width after 30 days, and had no problem of lateral shrinkage, whereas the expanded polytetrafluoroethylene fiber membrane prepared in comparative example 1 had a smaller lateral width after 10 days, 20 days, and 30 days, i.e., had a problem of lateral shrinkage.
FIG. 1 is a scanning electron microscope image of the expanded polytetrafluoroethylene fiber membrane prepared in example 3, in which the fiber membrane nodes are in a thin strip shape and are arranged in the transverse direction, and FIG. 2 is a scanning electron microscope image of the expanded polytetrafluoroethylene fiber membrane prepared in comparative example 1, in which the membrane structure is a network structure formed by fibers and nodes alternately, and the nodes are mostly circular or elliptical.
In conclusion, the expanded polytetrafluoroethylene fiber membrane prepared by the method can effectively solve the problem of transverse shrinkage of the fiber membrane on the basis of not affecting the membrane performance, and ensures the stability of the membrane size.
Claims (10)
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Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5814405A (en) * | 1995-08-04 | 1998-09-29 | W. L. Gore & Associates, Inc. | Strong, air permeable membranes of polytetrafluoroethylene |
| JP2000000885A (en) * | 1998-06-15 | 2000-01-07 | Toray Ind Inc | Polyester film and its production |
| KR20150079108A (en) * | 2013-12-31 | 2015-07-08 | 도레이케미칼 주식회사 | PTFE hollow fiber membrane and production method thereof |
| US20180369757A1 (en) * | 2015-08-31 | 2018-12-27 | Toray Industries, Inc. | Porous hollow fiber membrane |
| CN112936926A (en) * | 2019-12-10 | 2021-06-11 | 东莞先健新材料科技有限公司 | Polytetrafluoroethylene (PTFE) bulked film and preparation method thereof |
| CN113580456A (en) * | 2021-08-11 | 2021-11-02 | 浙江格尔泰斯环保特材科技股份有限公司 | Preparation method of polytetrafluoroethylene microporous film |
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Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5814405A (en) * | 1995-08-04 | 1998-09-29 | W. L. Gore & Associates, Inc. | Strong, air permeable membranes of polytetrafluoroethylene |
| JP2000000885A (en) * | 1998-06-15 | 2000-01-07 | Toray Ind Inc | Polyester film and its production |
| KR20150079108A (en) * | 2013-12-31 | 2015-07-08 | 도레이케미칼 주식회사 | PTFE hollow fiber membrane and production method thereof |
| US20180369757A1 (en) * | 2015-08-31 | 2018-12-27 | Toray Industries, Inc. | Porous hollow fiber membrane |
| CN112936926A (en) * | 2019-12-10 | 2021-06-11 | 东莞先健新材料科技有限公司 | Polytetrafluoroethylene (PTFE) bulked film and preparation method thereof |
| CN113580456A (en) * | 2021-08-11 | 2021-11-02 | 浙江格尔泰斯环保特材科技股份有限公司 | Preparation method of polytetrafluoroethylene microporous film |
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