CN1034315C

CN1034315C - Porous membrane preparation with polytetrafluorethylene

Info

Publication number: CN1034315C
Application number: CN94112057A
Authority: CN
Inventors: 宫香山; 瞿新昌
Original assignee: Individual
Current assignee: Individual
Priority date: 1994-02-26
Filing date: 1994-02-26
Publication date: 1997-03-26
Anticipated expiration: 2014-02-26
Also published as: CN1107383A

Abstract

The present invention discloses a novel method for preparing a porous film by ordinary molecular weight polyfluortetraethylene resin, which mixes low molecular weight resin with different brands by the intermiscibility among the low molecular weight resin with different brands and the extremely fine difference among surface tension according to certain proportion; then, the porous film is formed by expanding under the temperature of-10 to 1000 DEG C by a physical expanding method. The present invention has all the advantages for preparing the film by high molecular weight resin, the intensity and the glue are more excellent, a compound is easy to manufacture, and the present invention is suitable for continuous production in a large scale.

Description

Use porous membrane preparation with polytetrafluorethylene

The present invention is the new method for preparing the perforated membrane goods with polytetrafluoroethylene (PTFE), this method can prepare various porous tetrafluoro goods, as film, band, pipe, rod, be more suitable for some particular product, as hydrophilic membrane, reverse osmosis membrane, spy sense film, it is hydrophilic that wherein hydrophilic membrane both can be made into single face, also can be made into two-sided hydrophilic, and only just can be made into physical method, do not need with methods such as irradiation, grafting, copolymerization, thus can be on a large scale, serialization production.

The perforated membrane tetrafluoroethene, because of its good chemical resistance and physical property, its application is developed rapidly, but because of its complex manufacturing, to the ingredient requirement height, need use the super high molecular weight resin, thereby processing, promote, application is subjected to certain restriction, even so, carry out scanning electron microscope analysis for present commercially available film with the super high molecular weight resins, find that its micro-structural is inhomogeneous, fiber joint knot is excessive, too much, influence porosity, the aperture is also inhomogeneous; And with the film of general molecular weight resin preparation, its micro-structural differs greatly with the micro-structural of the film for preparing with super high molecular weight, the joint knot is bigger, be the state of can not draw away, the aperture is also more inhomogeneous, United States Patent (USP) U.S.P4187390 porous polymer and process introduction thereof with expansion method at 35 ℃ of-327 ℃ of intramedullary expansions of temperature, then 370 ℃-390 ℃ typings down, material need be used the super high molecular weight polyflon, manufacturer's product of production super high molecular weight resin is produced perforated membrane manufacturer at present and is monopolized, therefore supply out of stock on the market seeks that to obtain the aperture again without the super high molecular weight resin even, the joint knot is little, the way that porosity is high just seems very important.

The objective of the invention is to seek the processing method of a kind of economy, simple, the new porous Teflon that need not to use the super high molecular weight resin, Zhi Bei perforated membrane can keep the chemical property and the physical property of the film of original method processing and preparing in this way, and more excellent intensity and adhibit quality arranged, the easier composite membrane of making, can adapt to simultaneously low cost, extensive, serialization production again, to satisfy the needs in market.

For achieving the above object, the present invention is achieved like this, utilize and mix between the low-molecular-weight polyflon of the different trades mark and surface tension compole fine difference, they are mixed by a certain percentage, expand under temperature-10 ℃-1000 ℃ with physics expansion method then, the perforated membrane of its preparation has two kinds of structures, and a kind of is cloud sheet shape loose structure, and another kind is conventional fibre and joint junction structure.Cloud sheet shape loose structure, indefinite form does not bounce back yet, and fibre structure once can not bounce back through roll-in yet, and experiment is found: identical expansion multiple, temperature is low more, and the aperture is more little; Temperature is high more, and the aperture is big more, and identical temperature, low expansion multiple, the aperture is big, the high power expansion, the aperture is little, and the aperture is even, and porosity is also high, when lateral magnification is below 15 times, can also observe with 30,000 times of Electronic Speculum, when expanding to 20 times, 38 times, then need with 100,000 times of Electronic Speculum ability observation apertures, this shows: same apertures, the expansion temperature is low, and the expansion multiple is also low.The present invention's all technologies before expansion no longer repeat, after making perforated membrane with low molecular weight polytetrafluoroethylene, if further prepare hydrophilic membrane, reverse osmosis membrane etc. here all with conventional identical.Also need not to adopt irradiation, connect skill, copolymerization, only as long as a material that contains hydrophilic radical is scatter with solution, make with brushing, spraying, infusion process then to contain the hydrophilic radical material and stick to tetrafluoro pore membrane surface.Drying, sintering gets final product.Just as the processing raw material band deoils, drying, expand, finalize the design method, make it fuse surface firmly at film.

Below we the invention will be further described by several examples and electromicroscopic photograph thereof.

Example one raw material テ Off mouth Application 6-J (Teflon 6-J), F _R-202B Port リ Off mouth Application TFE F-103 (Polyflon TFE F-103), earlier with 0.2 times of raw material band vertical expansion, after get be of a size of the 10*10cm raw material band place-20 ℃ freezing 1 hour down, being put into temperature after the taking-up rapidly is with 3 times of 100%/second speed lateral magnifications in-5 ℃ the expansion device, during end, the film temperature is-10 ℃, micro-structural is seen stereoscan photograph 1, from photo 1 as can be seen: because the vertical expansion multiple is low, cause rectangular too much lateral magnification still passable, as long as 1～2 times of vertical expansion, thickness is reduced to 0.05mm by 0.1mm, when temperature is lower than zero degree, if do not carry out vertical expansion earlier, and carry out two-way expansion simultaneously, vertical multibreak splitting and can't expanding then, even when vertically only expanding minimum 0.2 times, it can also be seen that most fiber still ruptures.

Example two raw materials are with example one: the expansion temperature is 10 ℃, and with one times of 100%/second speed two-way simultaneous expansion, this moment, the resulting product aperture was very even, and the aperture is little, and the joint knot is also little, as stereoscan photograph 2, is described in more detail and sees example five.

Example three raw materials are with example one: 420 ℃ of expansion temperature, with 100%/second speed double is to expansion, three times of vertical expansions, five times of lateral magnifications, ESEM is seen photo 3, can find out from photo, this time knot draws back substantially, be that lines connect substantially between the fiber, film thickness is 0.004mm, and we use 0.6kg/cm this film ²Hydraulic pressure carries out dynamic test, promptly adds hydraulic pressure with impact method, non-ly slowly adds hydraulic pressure, and every impact pressurizes and one less important water is bled off, repeated stock ten times, and static five hours, film did not still seep water, not excreting dampness, air penetrability＞700ml/min10cm ²

Example four raw materials: Fluon CD-141 is with 0.2 times of sample elder generation vertical expansion, again under 600 ℃ with 1500%/5 times of second speed lateral magnifications, 7 times, 9 times, 15 times, 38 times, wherein 7,15,38 times of ESEMs are seen

photo

4,5,6, can find out that therefrom method lateral magnification multiple of the present invention is high more, the aperture is more little on the contrary, even more, micro-structural is the cloud sheet shape, this is absorbing, want to prepare the small-bore film, the expansion multiple should be big, 38 times of lateral magnifications, average pore size＜0.1 μ, but high power expansion varied in thickness is very big, reduces to 0.04mm by 0.2mm, and cross direction tensile strength also increases along with the increase of lateral magnification multiple forms doubly, substantially exceed longitudinal strength, this method has surpassed the boundary that in the past laterally only can expand several times.

Example Wuyuan material テ Off mouth Application (Teflon) 6-J, Port リ Off mouth Application TFE F-103, F _R-202A or B.6-J, F-103, F _R-203A or B are that three companies produce, wherein F _R-203A or B are Shanghai organic fluorine material research institute products, and three kinds of raw materials all are low-molecular-weight, low compression ratio resin, are used as the processing sealing and use raw material band, can not do film, and stereoscan photograph 7 is F-103, and photo 8 is CD-141, and photo 9 is 6-J, and photo 10 is F _R5000 times of enlarged photographs, wherein F when-202A makes film separately _RThe two-way expansion of-202A reaches two times, but structure is still very poor, and it is best to observe little knot CD-141 from photo, and 6-J takes second place, F _R-202A once more, F-103 is the poorest, best CD-141 compares with super high molecular weight film micro-structural (seeing photo 11～17), gap is too big, every kind of low-molecular-weight resin is processed separately, its expansion temperature just can have better structure about 300 ℃, certainly also be the structure of extreme difference, if wantonly two kinds of trade mark low-molecular-weight resins are mixed processing, about 200 ℃, the expansion multiple is also low, can meet and exceed the micro-structural of every kind of brand process of resin, though two kinds of mixed structures have more improvement, but still very poor, see photo 18, if respectively mix processing by 1/3 with these three kinds, miracle (seeing photo 2) has just taken place, and processing temperature all can pay off by-10 ℃-1000 ℃, and the expansion multiple is lower, photo 2 is 10 ℃ of expansions down, the two-way ESEM of respectively expanding one times 5000 times of amplifications, its micro-structural substantially exceeds the film with high molecular weight resin processing, arrives very ideal results.

Various resin ratio and result such as following table:

The resin kind	Ratio	Expansion temperature ℃	The micro-structural situation
The resin kind	Ratio	Expansion temperature ℃	The micro-structural situation	テ Off mouth Application (Teflon) 6-J	100％	＞300	Porosity is low, and the joint knot is bigger
Port リ Off mouth Application TFE F-103 polyflon TFE	100％	＞300	Porosity is low, and the joint knot greatly is plate-like	テ Off mouth Application (Teflon) 6-J	100％	＞300	Porosity is low, and the joint knot is bigger
Port リ Off mouth Application TFE F-103 polyflon TFE	100％	＞300	Porosity is low, and the joint knot greatly is plate-like	フルオン(Fluon) CD-141	100％	＞300	Porosity is low, and the joint knot is bigger
F _R-202B	100％	＞300	Porosity is low, and the bigger expansion multiple of joint knot is low	フルオン(Fluon) CD-141	100％	＞300	Porosity is low, and the joint knot is bigger
F _R-202B	100％	＞300		F-103+F _R-202B	Each is 50% years old	＞200	Porosity improves slightly, and the joint knot is still bigger than normal, and the expansion multiple is low
6-J+F _R-202A	Each is 50% years old	＞200	Porosity is higher, but the joint knot is still big	F-103+F _R-202B	Each is 50% years old	＞200
6-J+F _R-202A	Each is 50% years old	＞200	Porosity is higher, but the joint knot is still big	6-J+F-103+F _R-202B	Each is 1/3 years old	-10～1000	The porosity height, the aperture is little and even, and the low power expansion just surpasses super high molecular weight resin molding micro-structural

Example six: with any film in the above-mentioned example, use brushing, the jet printing type infusion process will have hydrophilic group because of the perfluor thing (as have carboxyl or sulfonic group because of perfluor ether etc.) solution, concentration 10%, brush or be sprayed on (as wanting two-sided hydrophilic available infusion process) on the film, coat drying and in 2 fens kinds of 250 ℃ of following sintering, make it to be bonded at the tetrafluoro surface with the firm fusion of tetrafluoro, because their surface tension is basic identical, therefore can well be combined into one, and need not use irradiation, grafting, copolymerization method makes, thereby serialization production in enormous quantities, especially with low cost as the dry technical process of deoiling of raw material band, the feeler of the hydrophilic film water that makes is less than 90 ℃, surface tension is not surveyed, but carry out testing experiment with direct-vision method more: the single face hydrophilic membrane that will the method for using makes is put into water and is taken out at once, then forming moisture film at hydrophilic surface is soaked, but not hydrophilic surface drips and is not stained with, with water droplet at hydrophilic surface, do not form the globule, make it wetting but ooze on the surface, and water droplet at hydrophobic surface, then form the globule, the globule is greatly to a certain degree being broken into a plurality of droplets, and surperficial no any moistening vestige

Claims

1. the technology for preparing perforated membrane with polyflon, it is characterized in that it utilizes mixes between the different trade mark low-molecular-weight resins and surface tension compole fine difference, mix by a certain percentage, expand with physical method then, under temperature-10 ℃-1000 ℃, expand, be prepared into cloud sheet shape loose structure film and conventional fibre joint junction structure perforated membrane, with the dispersion soln of this film with the band hydrophilic radical, make this hydrophilic radical material stick to the pore membrane surface with spraying, impregnating method, drying, sintering are made composite membrane.

2. press claims 1 described perforated membrane preparation technology, it is characterized in that identical expansion multiple, temperature is low more, and the aperture is more little; Temperature is high more, and the aperture is big more, identical temperature, and the expansion multiple is low more, and the aperture is then big; Otherwise expansion multiple height, the aperture is then little, and evenly, porosity is high more.

3. press claims 1 described perforated membrane preparation technology, it is characterized in that mixing with low-molecular-weight resin more than three kinds or three kinds, the expansion temperature is carried out under-10 ℃-1000 ℃.

4. press claims 1 described perforated membrane preparation technology, it is characterized in that the substance solution that contains hydrophilic radical is adopted brushing, impregnating method, make hydrophilic membrane (composite membrane).

5. press claims 1 described perforated membrane preparation technology, it is characterized in that the high power expansion method: 24 times-38 times.

6. press claims 1 described perforated membrane preparation technology, it is characterized in that being lower than 2 times expansion.