CN100431678C - Surface hydrophilicity modification process for separating fluoric polymer film - Google Patents
Surface hydrophilicity modification process for separating fluoric polymer film Download PDFInfo
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- CN100431678C CN100431678C CNB2006101548926A CN200610154892A CN100431678C CN 100431678 C CN100431678 C CN 100431678C CN B2006101548926 A CNB2006101548926 A CN B2006101548926A CN 200610154892 A CN200610154892 A CN 200610154892A CN 100431678 C CN100431678 C CN 100431678C
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- diffusion barrier
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Abstract
The process of modifying surface hydrophilicity of separating fluoric polymer film includes the first pre-irradiating separating fluoric polymer film with high energy ray to make the surface macromolecular main chain generate active free radical, and the subsequent grafting the surface fluoric polymer film with high ionized hydrophilic sulfonic group in the grafting polymerization reaction system with double monomer of acrylic cid and sodium styrene sulfonate and water as dispersing medium in controlled reactant concentration, molar ratio, temperature and pH value. The process can improve the hydrophilicity of separating fluoric polymer film obviously, and the modified separating membrane has obviously decreased contact angle and lasting hydrophilicity.
Description
Technical field
The invention belongs to the membrane separation technique field, particularly a kind of graft reaction technology of the fluoropolymer diffusion barrier being carried out surface modification.Be exactly by the graft copolymerization of pre-irradiation specifically, introduce the ionization sulfonic acid group of highly-hydrophilic in hydrophobic separation membrane surface one-step method at fluoropolymer separation membrane surface initiation acrylic acid and SSS.
Background technology
Fluoropolymer such as Kynoar (PVDF), polytetrafluoroethylene (PTFE)s etc. are the membrane materials of some high comprehensive performances, the chemical stability that it is outstanding, heat endurance, low-surface-energy and dielectric properties receive increasing concern, are with a wide range of applications at the film separation field.Strong-hydrophobicity makes it occupy special advantages in film separation processes such as film distillation, film absorption and gas purifications, but hydrophobic microporous barrier can produce two problems when handling the aqueous phase separation system: the one, and the surface can be low, fluid sees through the mass transfer driving force height of film, and energy consumption is big, and water flux is low; The 2nd, very easily adsorb organic compound, protein etc. cause film to pollute, and cause flux to descend, and membrane lifetime shortens.Therefore by hydrophilic modification, cut down the consumption of energy, strengthen the film contamination resistance, to prolong film very necessary service life.Surface graft modification only changes the hydrophily on film surface, does not change the structure and the character of membrane material matrix, and grafted chain has long-term stability with covalent bond and microporous barrier surface bond, thereby can not cause the loss of grafted chain in the film use.Because carbon-fluorine bond bond energy very big (485.7KJ/mol), fluoropolymer has very strong chemical stability, and the more low-energy method of radiating such as chemical modification, ultraviolet irradiation that are difficult to by routine carry out modification to its surface.Therefore study the technology that is suitable for the fluoropolymer surface modification and have important theory and practice significance.In existing irradiation grafting technology, because the irradiance method of mutual radiation and peroxide/hydrogen peroxide is to treat that grafted monomers directly places irradiation, can produce more homopolymers that pre-irradiation then can be avoided this problem.In the high-energy ray of existing large-scale application, the gamma-rays penetration power is strong, and reaction is even, and operation easily; High-power electron beam not only have the cleaning of common radiation chemistry, fast, accurately, save advantage such as the energy, but also it is big to have a radiation dose rate, the manageable characteristics of switch are suitable for the graft modification of fluoropolymer separation membrane surface, also are suitable for large-scale production.Hydrophiling research for fluoropolymer microporous barrier high-energy ray irradiation surface grafting, generally be some hydrophilic monomers of grafting such as acrylic acid in the irradiation process or behind the irradiation, acrylamide, styrene etc., SSS for highly-hydrophilic then can not be directly grafted to hydrophobic fluoropolymer diffusion barrier film surface, and this is because highly Ionized sulfonic acid group (SO
2- 3) easily form spherical hydrated ion, can not be compatible with hydrophobic fluoropolymer diffusion barrier, hinder monomer and be diffused into separation membrane surface, thus let alone one-step method grafting.So mostly adopt grafting and sulfonation two-step method to carry out hydrophilic modification: at first be with gamma-ray irradiation fluoropolymer diffusion barrier at fluoropolymer separation membrane surface grafting sulfonic group monomer, produce living radical on its surface, then with the styrene copolymerized Modified Membrane of certain-length polystyrene chain that obtained surface grafting, utilize the reactivity of phenyl ring in the polystyrene chain then, carry out sulfonating reaction with the concentrated sulfuric acid, obtain the fluoropolymer diffusion barrier that the hydrophily sulfonic acid group is contained on the surface.The present invention is by high-energy ray pre-irradiation fluoropolymer separation membrane surface, and by one-step method in the grafting of fluoropolymer separation membrane surface acrylic acid and SSS monomer, improved the hydrophily of fluoropolymer diffusion barrier significantly.
Summary of the invention
The purpose of this invention is to provide and a kind ofly carry out hydrophilic modification method easily, eco-friendly, to realize regulation and control separation membrane surface character at the fluoropolymer separation membrane surface.
The step of method is as follows:
1) with the fluoropolymer diffusion barrier of weighing, put into the sample sack inflated with nitrogen and vacuumize 2～4 times repeatedly, pre-irradiation is carried out in sealing under high-energy ray then, and the fluoropolymer diffusion barrier behind the irradiation is preserved stand-by down at-10～-20 ℃;
2) with water be decentralized medium, with acrylic acid and SSS is two monomer systems, the preparation mixed water solution, the monomer molar proportioning is SSS/acrylic acid=1: 5～5: 1, monomer concentration is 0.1～5mol/L, regulating the pH value is 2.0～9.0, under nitrogen protection, the fluoropolymer diffusion barrier behind the above-mentioned irradiation is immersed in this solution, carry out the surface grafting polymerization reaction, the control reaction temperature is 20 ℃～80 ℃, and the reaction time is 0.5～10 hour;
3) above-mentioned fluoropolymer diffusion barrier through the surface grafting polymerization reaction is taken out, be that cleaning solvent carries out extracting or immersion with ethanol and deionized water respectively, the ethanol extracting time is 6～12 hours, the deionized water soak time is 12～24 hours, cleaning temperature is 30 ℃～60 ℃, remove be deposited on the surface homopolymers or unreacted monomer, 50～90 ℃ of following vacuum drying to constant weight, obtain the fluoropolymer diffusion barrier of hydrophilic modification, percent grafting adopts weight method to calculate.
As preferably, described high-energy ray is gamma-rays or high-power electron beam, and the dosage of its pre-irradiation is 10～200KGy.The polymer separation film material is Kynoar or polytetrafluoroethylene (PTFE).The pH value of mixed water solution is 1.0～7.0, and the monomer molar proportioning is SSS/acrylic acid=1: 3～3: 1, and monomer concentration is 0.5～3mol/L.The reaction temperature of surface grafting polymerization reaction is 40 ℃～80 ℃, and the reaction time is 0.5～5 hour.The fluoropolymer diffusion barrier is dull and stereotyped homogeneous membrane, composite membrane, tubular membrane or hollow-fibre membrane.The fluoropolymer diffusion barrier is micro-filtration membrane or milipore filter.
Advantage of the present invention is:
1) preliminary treatment is adopted high-energy ray, easy to control, serialization, good reproducibility, is suitable for large-scale industrial production;
2) adopt the method for pre-irradiation that film is carried out preliminary treatment, can produce less homopolymers, it is simple to clean last handling process;
3) adopt two monomer systems, utilize the compatibility difference of acrylic acid/SSS and fluoropolymer, one-step method is carried out surface graft modification, and operating procedure is simple, good reproducibility, and the percent grafting optimum range is controlled at 1-10wt%;
4) adopt the aqueous solution as the reaction decentralized medium, environmental friendliness, with low cost.
Description of drawings
PVDF homogeneous membrane surface SEM photo when Fig. 1 (a) is not grafting;
Fig. 1 (b) is that percent grafting is 3.0% o'clock PVDF homogeneous membrane surface SEM photo;
PTFE homogeneous membrane surface SEM photo when Fig. 2 (a) is not grafting;
Fig. 2 (b) is that percent grafting is 5.7% o'clock PTFE homogeneous membrane surface SEM photo;
PVDF composite membrane surface SEM photo when Fig. 3 (a) is not grafting;
Fig. 3 (b) is that percent grafting is 12.2% o'clock composite membrane surface SEM photo;
PTFE composite membrane surface SEM photo when Fig. 4 (a) is not grafting;
Fig. 4 (b) is that percent grafting is 7.5% o'clock PTFE composite membrane surface SEM photo;
PVDF hollow-fibre membrane surface SEM photo when Fig. 5 (a) is not grafting;
Fig. 5 (a) is that percent grafting is 4.0% o'clock PVDF hollow-fibre membrane table SEM photo;
Fig. 6 (a) is that percent grafting is 2.5% o'clock PTFE tube formula film inner surface SEM photo;
Fig. 6 (b) is that percent grafting is 2.5% o'clock PTFE tube formula film outer surface SEM photo;
The specific embodiment
The present invention adopts high-energy ray that the fluoropolymer separation membrane surface is carried out pre-irradiation, and the dosage of pre-irradiation is controlled at 10～150KGy.
The polymer separation film material that the present invention uses is: Kynoar (PVDF) and polytetrafluoroethylene (PTFE).
The graft-modification method that the present invention adopts is the reaction of one-step method graft polymers, and grafted monomers is meant SSS (SSS) and acrylic acid (AAc), and the monomer molar proportioning is SSS/AAc=1: 3～3: 1, and monomer concentration is 0.5～3mol/L.
The decentralized medium of the said one-step method graft reaction of the present invention is: water, monomer solution pH value is 1.0～7.0.
The post processing cleaning solvent that the present invention adopts is: ethanol and deionized water, and the extracting time is 6～12 hours, soak time is 12～24 hours.
The percent grafting of fluoropolymer is to adopt weight method to calculate after the modification of the present invention.The measurement of water flux is to adopt laboratory homemade dead-end filtration water flux determinator, promptly earlier at 0.15MPa precompressed 30min, measures the permeation flux of its pure water then at 0.1MPa.
The apparent static contact angle on film surface be by OCA20 (
Germany) video contact angle measurement is measured.Get ten diverse locations of film and measure, get its mean value and obtain contact angle.The configuration of surface of fluoro-containing copolymer film adopts ESEM to observe before and after the modification.
Be described in further detail below in conjunction with application example, but these examples are not used for limiting the present invention.
Embodiment 1
The concrete operations step is as follows:
1) with the Kynoar homogeneous membrane of weighing, putting into the sample sack inflated with nitrogen vacuumizes 3 times repeatedly, sealing then, under high-power electron beam, carry out pre-irradiation, the dosage of pre-irradiation is 30KGy, for fear of the quick extinction of film surface free radical, the Kynoar homogeneous membrane behind the irradiation is preserved stand-by down at-20 ℃;
2) with water be decentralized medium, with acrylic acid and SSS is two monomer systems, the preparation mixed water solution, the monomer molar proportioning is SSS/acrylic acid=3/1, monomer concentration is 0.5mol/L, regulating the pH value is 3.5, Kynoar homogeneous membrane behind the above-mentioned irradiation is immersed in this solution, under nitrogen protection, carry out the surface grafting polymerization reaction, the control reaction temperature is 60 ℃, and the reaction time is 2 hours;
3) above-mentioned fluoropolymer diffusion barrier through the surface grafting polymerization reaction is taken out, be that cleaning solvent carries out extracting or immersion with ethanol and deionized water respectively, the ethanol extracting time is 12 hours, the deionized water soak time is 24 hours, cleaning temperature is 60 ℃, remove the homopolymers or the unreacted monomer that are deposited on the surface, to constant weight, obtain the fluoropolymer diffusion barrier of hydrophilic modification 50 times vacuum drying.
4) adopt weight method to calculate its percent grafting, and measure its apparent static contact angle and water flux.
The detail operations parameter of above-mentioned steps and structure and performance parameter see the following form, and mode of appearance is seen description of drawings.
Embodiment 2 concrete operations steps are with embodiment 1.
Embodiment 3 concrete operations steps are with embodiment 1.
Embodiment 4 concrete operations steps are with embodiment 1.
Embodiment 5 concrete operations steps are with embodiment 1.
Embodiment 6 concrete operations steps are with embodiment 1.
Embodiment 7 concrete operations steps are with embodiment 1.
Embodiment 8 concrete operations steps are with embodiment 1.
Claims (6)
1. fluoropolymer separation membrane surface hydrophilic modification method, the step of method is as follows:
1) with the fluoropolymer diffusion barrier of weighing, putting into the sample sack inflated with nitrogen vacuumizes 2～4 times repeatedly, sealing then, under high-energy ray, carry out pre-irradiation, fluoropolymer diffusion barrier behind the irradiation is preserved stand-by down at-10～-20 ℃, high-energy ray is gamma-rays or high-power electron beam, and the dosage of its pre-irradiation is 10-200KGy;
2) with water be decentralized medium, with acrylic acid and SSS is two monomer systems, the preparation mixed water solution, the monomer molar proportioning is SSS/acrylic acid=1: 5～5: 1, monomer concentration is 0.1～5mol/L, regulating the pH value is 2.0～9.0, under nitrogen protection, the fluoropolymer diffusion barrier behind the above-mentioned irradiation is immersed in this solution, carry out the surface grafting polymerization reaction, the control reaction temperature is 20 ℃～80 ℃, and the reaction time is 0.5～10 hour;
3) above-mentioned fluoropolymer diffusion barrier through the surface grafting polymerization reaction is taken out, be that cleaning solvent carries out extracting or immersion with ethanol and deionized water respectively, the ethanol extracting time is 6～12 hours, the deionized water soak time is 12～24 hours, cleaning temperature is 30 ℃～60 ℃, remove be deposited on the surface homopolymers or unreacted monomer, 50～90 ℃ of following vacuum drying to constant weight, obtain the fluoropolymer diffusion barrier of hydrophilic modification, percent grafting adopts weight method to calculate.
2. a kind of fluoropolymer separation membrane surface hydrophilic modification method according to claim 1 is characterized in that described polymer separation film material is Kynoar or polytetrafluoroethylene (PTFE).
3. a kind of fluoropolymer separation membrane surface hydrophilic modification method according to claim 1 is characterized in that described monomer molar proportioning is SSS/acrylic acid=1: 3～3: 1, and monomer concentration is 0.5～3mol/L.
4. a kind of fluoropolymer separation membrane surface hydrophilic modification method according to claim 1 is characterized in that the reaction temperature of described surface grafting polymerization reaction is 40 ℃～80 ℃, and the reaction time is 0.5～5 hour
5. a kind of fluoropolymer separation membrane surface hydrophilic modification method according to claim 1 is characterized in that described fluoropolymer diffusion barrier is dull and stereotyped homogeneous membrane, composite membrane, tubular membrane or hollow-fibre membrane.
6, a kind of fluoropolymer separation membrane surface hydrophilic modification method according to claim 1 is characterized in that described fluoropolymer diffusion barrier is micro-filtration membrane or milipore filter.
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Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101485960B (en) * | 2009-01-09 | 2011-08-17 | 清华大学 | Method for modifying interpenetrating polymer network on surface of polyvinylidene fluoride porous membrane |
| CN101780377B (en) * | 2010-03-09 | 2012-06-20 | 天津膜天膜工程技术有限公司 | Method for preparing compound nanofiltration membrane |
| CN102477163B (en) * | 2011-07-29 | 2014-04-16 | 深圳光启高等理工研究院 | Preparation method for macromolecular material based microstructure |
| CN103182258A (en) * | 2011-12-30 | 2013-07-03 | 江苏大孚膜科技有限公司 | Preparation method of gamma-ray co-irradiated monomer acrylic acid graft ultrafiltration flat sheet membrane |
| CN102580573B (en) * | 2012-03-01 | 2013-12-25 | 天津工业大学 | Method for producing perfluor polymer hollow fiber membrane |
| CN104497331A (en) * | 2014-12-29 | 2015-04-08 | 沈阳理工大学 | Method for increasing wettability of polytetrafluoroethylene film employing electron beam radiation |
| CN106268366A (en) * | 2016-08-08 | 2017-01-04 | 天津工业大学 | The preparation method and applications of modified polypropene hollow-fibre membrane |
| CN113230910B (en) * | 2021-05-07 | 2022-10-18 | 浙江鹏辰造纸研究所有限公司 | Hydrophilic modification method of polytetrafluoroethylene microporous membrane |
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| US5042993A (en) * | 1990-07-24 | 1991-08-27 | Air Products And Chemicals, Inc. | Gas separating membranes from polyimide polymers |
| CN1224730A (en) * | 1998-07-20 | 1999-08-04 | 天津纺织工学院膜天膜技术工程公司 | Method of producing composite porous polymetafluoroethylene film |
| CN1523639A (en) * | 2003-02-17 | 2004-08-25 | ���µ�����ҵ��ʽ���� | Photomask, pattern formation method using photomask and mask data creation method |
| CN1539550A (en) * | 2003-11-03 | 2004-10-27 | 浙江大学 | Method for modifying hydroophilicity of highly active separation membrane made from polymer |
| US20050139545A1 (en) * | 2002-03-12 | 2005-06-30 | Rensselaer Polytechnic , A New York Corporation, | Photo-processing and cleaning of pes and psf membranes |
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Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5042993A (en) * | 1990-07-24 | 1991-08-27 | Air Products And Chemicals, Inc. | Gas separating membranes from polyimide polymers |
| CN1224730A (en) * | 1998-07-20 | 1999-08-04 | 天津纺织工学院膜天膜技术工程公司 | Method of producing composite porous polymetafluoroethylene film |
| US20050139545A1 (en) * | 2002-03-12 | 2005-06-30 | Rensselaer Polytechnic , A New York Corporation, | Photo-processing and cleaning of pes and psf membranes |
| CN1523639A (en) * | 2003-02-17 | 2004-08-25 | ���µ�����ҵ��ʽ���� | Photomask, pattern formation method using photomask and mask data creation method |
| CN1539550A (en) * | 2003-11-03 | 2004-10-27 | 浙江大学 | Method for modifying hydroophilicity of highly active separation membrane made from polymer |
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