CN102908910A - Preparing method of polyvinylidene fluoride porous membrane - Google Patents
Preparing method of polyvinylidene fluoride porous membrane Download PDFInfo
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- CN102908910A CN102908910A CN2012104628330A CN201210462833A CN102908910A CN 102908910 A CN102908910 A CN 102908910A CN 2012104628330 A CN2012104628330 A CN 2012104628330A CN 201210462833 A CN201210462833 A CN 201210462833A CN 102908910 A CN102908910 A CN 102908910A
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Abstract
The invention provides a preparing method of a polyvinylidene fluoride porous membrane, wherein an extrusion casting-stretching method is adopted. The preparing method includes the following steps: polyvinylidene fluoride casting-stretching melt is stretched and subjected to thermal treatment, and then a melt stretching membrane is subjected to cold drawing and hot drawing to form a porous structure. Compared with the melt phase conversion and thermal induced phase separation method adopted by the exiting polyvinylidene fluoride porous membrane preparing method, no any auxiliaries or solvents are needed to be added in the production process by adopting the casting-stretching method, and the preparing method of the polyvinylidene fluoride porous membrane has the advantages of being safe, environment-friendly, simple in process, continuous in production and the like.
Description
Technical field
The present invention relates to a kind of preparation method of polyvinylidene fluoride porous film.
Background technology
Kynoar (PVDF) perforated membrane is owing to have good electrolyte wellability, good chemical stability, heat-resisting, weather-proof and anti-bioerosion ability, has been widely used in organic matter/moisture from fields such as, trade effluent processing, drink water purifying, polymer dielectric, vanadium cell barrier films.
The preparation method of polyvinylidene fluoride porous film mainly contains solution phase transition method and thermally induced phase separation at present.Wherein, solution phase changes the standby basic process of legal system and comprises: first polyvinylidene fluoride resin and polar solvent are hybridly prepared into uniform solution, then polymer solution is immersed in the non-solvent coagulating baths such as water, pure and mild ketone, by the effect that the solvent in the polymer solution spreads in to non-solvent diffusion and non-solvent to polymer, final formation contains the polyvinylidene difluoride film of micropore.The shortcoming of this production technology maximum is that production process needs a large amount of solvents, and the production safety coefficient is low and have certain contaminative.Chinese patent No.200510086337 discloses a kind of thermic and has been separated and prepares the method for polyvinylidene fluoride flat plate porous film.The method is first polyvinylidene fluoride resin and diluent to be mixed into homogeneous phase solution under 110 ~ 140 ℃, and through filtration, deaeration, leave standstill etc. and form casting solution.Then casting solution is poured into the mould calendering formation, and through the process of overheated maintenance and cooling curing moulding.At last, the diaphragm that solidifies is put into extractant soaked 2 ~ 4 days, with the diluent in the extraction diaphragm, and finally obtain polyvinylidene fluoride microporous film.The polyvinylidene fluoride microporous film isotropism of the method preparation, without orientation, so the mechanical property of film is relatively poor.And the production process of this technique is comparatively complicated, and continuity is relatively poor, and production cost is higher.In Chinese patent CN101569837A, the method that proposes the employing composite thinning agent has further improved the performance of microporous barrier.Unavoidably will use a large amount of diluents and extractant in thermal induction is separated preparation microporous barrier process, what bring equally is environmental protection and safety issue.
Summary of the invention
The invention provides a kind of method that curtain coating-pulling method prepares polyvinylidene fluoride porous film of extruding.Need not to add any pore former in the method production process and use any solvent, have the characteristics such as continuity is good, technique simple, safety and environmental protection.Wherein, the principle of film forming is that polyvinylidene fluoride resin is at first formed perpendicular to the lamellar structure that is arranged in parallel of extruding direction after the match extruding curtain coating melt tensile stress.Film with this lamellar structure can separate between platelet and the platelet and produces loose structure under specific stretching condition.
The present invention is achieved by the following technical solutions:
The preparation method of a kind of polyvinylidene fluoride porous film provided by the invention has the following steps:
1) be that the polyvinylidene fluoride resin of 0.8 ~ 6g/10min melt extrudes in 200 ~ 250 ℃ extruder with melt index;
2) with above-mentioned Kynoar melt extruding curtain coating on the casting machine, cool off at chill roll, by carry-over pinch rolls, reel at coiler device at last, obtain initial film; Wherein, the casting roller temperature is 80 ~ 120 ℃, convoluting speed 10～40m/min, molding thickness 10～40um, mouthful mould die lip gap 0.8～2mm, melt range of stretch 2～10mm, melt-draw ratio 35～60;
3) with the initial film heat treatment 5 ~ 60min under 100 ~ 150 ℃ of conditions of temperature that makes, and obtain heat-treating film;
4) with heat-treating film 30～45 ℃, stretch with the rate of extension of 20～80mm/min, and it is stretched to 15 ~ 40% deformation; Then, under 130～150 ℃ condition, be stretched to 50～200%; At last, carry out thermal finalization under the effect that keeps tensile stress, wherein heat setting temperature is 120 ~ 150 ℃, and heat-setting time is 5 ~ 60min, obtains polyvinylidene fluoride porous film.
Above-mentioned steps 1) in, used polyvinylidene fluoride resin is the homopolymerization polyvinylidene fluoride resin.
Above-mentioned steps 1) in, used extruder is single screw extrusion machine or double screw extruder.
Above-mentioned steps 3) in, heat treatment process is discontinuous carrying out or on-line continuous heat treatment in drying tunnel in baking oven.
Above-mentioned steps 4) in, under 130～150 ℃ condition, be stretched to 50～200%, this process is that single-point stretches or multiple spot stretches, such as minute 6 or 8 stretchings.Afterwards, carry out thermal finalization and process, in the thermal finalization processing procedure,, need to bounce back retraction ratio 5～20% in order to control the shrinkage factor of perforated membrane.
The polyvinylidene fluoride porous film porosity of the present invention's preparation is adjustable in 20 ~ 60% scopes, and polyvinylidene fluoride porous film is used for the key areas such as lithium battery, vanadium cell, desalinization and sewage disposal.
Beneficial effect of the present invention:
The present invention and existing polyvinylidene fluoride porous film preparation method: solvent phase changes to be compared with thermally induced phase separation, extrude curtain coating-pulling method and need not in process of production to add any auxiliary agent and solvent, have the advantages such as safety and environmental protection, technique is simple and can produce continuously.
Description of drawings
Fig. 1 is process chart of the present invention.
Fig. 2 is the Kynoar heat-treating film sem test result of the embodiment of the invention 1 preparation.
Fig. 3 is the polyvinylidene fluoride porous film sem test result of the embodiment of the invention 1 preparation.
The specific embodiment
The below further describes the present invention in the mode of embodiment, but these embodiment do not limit the scope of the present invention.
Embodiment 1
The polyvinylidene fluoride resin that with melt index is 0.8g/10min melt extrudes under 240 ℃, and is extruding casting film-forming on the casting machine.Wherein the casting roller temperature is 90 ℃, melt-draw ratio 35.Then with initial film heat treatment 30min under 120 ℃ of conditions, and obtain heat-treating film.Again with under 30 ℃ of the heat-treating films, stretch with the rate of extension of 30mm/min, and it is stretched to 20% deformation, and under 130 ℃, with identical rate of extension, heat-treating film further is stretched to 50% deformation.At last, obtain polyvinylidene fluoride porous film at 140 ℃ of lower thermal finalization 30min.
Embodiment 2
The polyvinylidene fluoride resin that with melt index is 0.8g/10min melt extrudes under 240 ℃, and is extruding casting film-forming on the casting machine.Wherein the casting roller temperature is 100 ℃, and melt-draw ratio is 40.Then with initial film heat treatment 40min under 130 ℃ of conditions, and obtain heat-treating film.Again with under 35 ℃ of the heat-treating films, stretch with the rate of extension of 40mm/min, and it is stretched to 25% deformation, and under 135 ℃, with identical rate of extension, heat-treating film further is stretched to 55% deformation.At last, obtain polyvinylidene fluoride porous film at 145 ℃ of lower thermal finalization 30min.
Embodiment 3
The polyvinylidene fluoride resin that with melt index is 0.8g/10min melt extrudes under 210 ℃, and is extruding casting film-forming on the casting machine.Wherein the casting roller temperature is 110 ℃, and melt-draw ratio is 50.Then with initial film heat treatment 30min under 140 ℃ of conditions, and obtain heat-treating film.Again with under 40 ℃ of the heat-treating films, stretch with the rate of extension of 50mm/min, and it is stretched to 20% deformation, and under 140 ℃, with identical rate of extension, heat-treating film further is stretched to 55% deformation.At last, obtain polyvinylidene fluoride porous film at 140 ℃ of lower thermal finalization 45min.
Embodiment 4
The polyvinylidene fluoride resin that with melt index is 0.8g/10min melt extrudes under 210 ℃, and is extruding casting film-forming on the casting machine.Wherein the casting roller temperature is 115 ℃, and melt-draw ratio is 55.Then with initial film heat treatment 60min under 140 ℃ of conditions, and obtain heat-treating film.Again with under 40 ℃ of the heat-treating films, stretch with the rate of extension of 70mm/min, and it is stretched to 40% deformation, and under 150 ℃, with identical rate of extension, heat-treating film further is stretched to 70% deformation.At last, obtain polyvinylidene fluoride porous film at 150 ℃ of lower thermal finalization 60min.
Embodiment 5
The polyvinylidene fluoride resin that with melt index is 2g/10min melt extrudes under 230 ℃, and is extruding casting film-forming on the casting machine.Wherein the casting roller temperature is 120 ℃, and melt-draw ratio is 60.Then with initial film heat treatment 20min under 100 ℃ of conditions, and obtain heat-treating film.Again with under 45 ℃ of the heat-treating films, stretch with the rate of extension of 80mm/min, and it is stretched to 15% deformation, and under 150 ℃, with identical rate of extension, heat-treating film further is stretched to 200% deformation.At last, obtain polyvinylidene fluoride porous film at 120 ℃ of lower thermal finalization 20min.
Embodiment 6
The polyvinylidene fluoride resin that with melt index is 3g/10min melt extrudes under 250 ℃, and is extruding casting film-forming on the casting machine.Wherein the casting roller temperature is 80 ℃, and melt-draw ratio is 55.Then with initial film heat treatment 10min under 110 ℃ of conditions, and obtain heat-treating film.Again with under 40 ℃ of the heat-treating films, stretch with the rate of extension of 70mm/min, and it is stretched to 20% deformation, and under 125 ℃, with identical rate of extension, heat-treating film further is stretched to 100% deformation.At last, obtain polyvinylidene fluoride porous film at 130 ℃ of lower thermal finalization 60min.
Embodiment 7
The polyvinylidene fluoride resin that with melt index is 6g/10min melt extrudes under 210 ℃, and is extruding casting film-forming on the casting machine.Wherein the casting roller temperature is 115 ℃, and melt-draw ratio is 60.Then with initial film heat treatment 60min under 140 ℃ of conditions, and obtain heat-treating film.Again with under 40 ℃ of the heat-treating films, stretch with the rate of extension of 70mm/min, and it is stretched to 40% deformation, and under 150 ℃, with identical rate of extension, heat-treating film further is stretched to 70% deformation.At last, obtain polyvinylidene fluoride porous film at 150 ℃ of lower thermal finalization 60min.
Comparative example
The polyvinylidene fluoride resin that with melt index is 0.8g/10min melt extrudes under 210 ℃, and is extruding casting film-forming on the casting machine.Wherein the casting roller temperature is 115 ℃, and melt-draw ratio is 20.Then with initial film heat treatment 60min under 140 ℃ of conditions, and obtain heat-treating film.Again with under 40 ℃ of the heat-treating films, stretch with the rate of extension of 70mm/min, and it is stretched to 35% deformation, and under 150 ℃, with identical rate of extension, heat-treating film further is stretched to 70% deformation.At last, obtain polyvinylidene fluoride film at 150 ℃ of lower thermal finalization 60min.
Table 1 properties of sample relatively
| ? | Embodiment 1 | Embodiment 2 | Embodiment 3 | Embodiment 4 | Embodiment 5 | Embodiment 6 | Embodiment 7 | Comparative example |
| Casting films rebound degree % | 50 | 66 | 80 | 91 | 45 | 89 | 73 | 35 |
| Perforated membrane porosity % | 30 | 35 | 45 | 60 | 30 | 60 | 51 | 4.5 |
By as seen from Table 1, compare comparative example, in the raising of extruding curtain coating process melt-draw ratio, the casting films rebound degree improves.Perforated membrane porosity corresponding behind the drawn also obviously improves.What Fig. 2 provided is the casting films micro-structure diagram, has as seen obviously formed to have the lamellar structure that is arranged in parallel perpendicular to extruding direction in sample.Fig. 3 is stretched rear perforated membrane microstructure, and as seen, platelet is separated in and forms micropore in the sample after stretching.
Claims (5)
1. the preparation method of a polyvinylidene fluoride porous film is characterized in that the method has the following steps:
1) be that the polyvinylidene fluoride resin of 0.8 ~ 6g/10min melt extrudes in 200 ~ 250 ℃ extruder with melt index;
2) with above-mentioned Kynoar melt extruding curtain coating on the casting machine, cool off at chill roll, by carry-over pinch rolls, reel at coiler device at last, obtain initial film; Wherein, the casting roller temperature is 80 ~ 120 ℃, convoluting speed 10～40m/min, molding thickness 10～40um, mouthful mould die lip gap 0.8～2mm, melt range of stretch 2～10mm, melt-draw ratio 35～60;
3) with the initial film heat treatment 5 ~ 60min under 100 ~ 150 ℃ of conditions of temperature that makes, and obtain heat-treating film;
4) with heat-treating film 30～45 ℃, stretch with the rate of extension of 20～80mm/min, and it is stretched to 15 ~ 40% deformation; Then, under 130～150 ℃ condition, be stretched to 50～200%; At last, carry out thermal finalization under the effect that keeps tensile stress, wherein heat setting temperature is 120 ~ 150 ℃, and heat-setting time is 5 ~ 60min, obtains polyvinylidene fluoride porous film.
2. preparation method as claimed in claim 1, it is characterized in that: above-mentioned steps 1), used polyvinylidene fluoride resin is the homopolymerization polyvinylidene fluoride resin.
3. preparation method as claimed in claim 1, it is characterized in that: above-mentioned steps 1), used extruder is single screw extrusion machine or double screw extruder.
4. preparation method as claimed in claim 1, it is characterized in that: above-mentioned steps 3), heat treatment process is discontinuous carrying out or on-line continuous heat treatment in drying tunnel in baking oven.
5. preparation method as claimed in claim 1 is characterized in that: above-mentioned steps 4), under 130～150 ℃ condition, be stretched to 50～200%, this process is that single-point stretches or multiple spot stretches.
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104857864A (en) * | 2015-05-27 | 2015-08-26 | 广东工业大学 | Poly(4-methyl-1-pentene) microporous membrane and preparation method thereof |
| CN106178990A (en) * | 2016-08-29 | 2016-12-07 | 天津市尚拓环保科技有限公司 | A kind of high-strength polyvinylidene fluoride ultrafiltration membrane filaments preparation technology |
| CN106621861A (en) * | 2016-11-22 | 2017-05-10 | 广东工业大学 | Preparation method of polyvinylidene fluoride microporous membrane |
| CN109216633A (en) * | 2018-09-19 | 2019-01-15 | 广东工业大学 | A kind of MULTILAYER COMPOSITE aliphatic polyketone microporous barrier and preparation method thereof |
| CN109256514A (en) * | 2018-09-19 | 2019-01-22 | 广东工业大学 | MULTILAYER COMPOSITE aliphatic polyketone microporous barrier and preparation method thereof |
| CN109263074A (en) * | 2018-09-19 | 2019-01-25 | 广东工业大学 | A kind of aliphatic polyketone microporous barrier and preparation method thereof |
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Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104857864A (en) * | 2015-05-27 | 2015-08-26 | 广东工业大学 | Poly(4-methyl-1-pentene) microporous membrane and preparation method thereof |
| CN106178990A (en) * | 2016-08-29 | 2016-12-07 | 天津市尚拓环保科技有限公司 | A kind of high-strength polyvinylidene fluoride ultrafiltration membrane filaments preparation technology |
| CN106621861A (en) * | 2016-11-22 | 2017-05-10 | 广东工业大学 | Preparation method of polyvinylidene fluoride microporous membrane |
| CN109216633A (en) * | 2018-09-19 | 2019-01-15 | 广东工业大学 | A kind of MULTILAYER COMPOSITE aliphatic polyketone microporous barrier and preparation method thereof |
| CN109256514A (en) * | 2018-09-19 | 2019-01-22 | 广东工业大学 | MULTILAYER COMPOSITE aliphatic polyketone microporous barrier and preparation method thereof |
| CN109263074A (en) * | 2018-09-19 | 2019-01-25 | 广东工业大学 | A kind of aliphatic polyketone microporous barrier and preparation method thereof |
| CN109216633B (en) * | 2018-09-19 | 2021-07-06 | 广东工业大学 | Multilayer composite aliphatic polyketone microporous membrane and preparation method thereof |
| CN109256514B (en) * | 2018-09-19 | 2021-09-21 | 广东工业大学 | Multilayer composite aliphatic polyketone microporous membrane and preparation method thereof |
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Application publication date: 20130206 |