CN110917890A - Hydrophilic agent, modified ethylene-chlorotrifluoroethylene membrane and preparation method thereof - Google Patents
Hydrophilic agent, modified ethylene-chlorotrifluoroethylene membrane and preparation method thereof Download PDFInfo
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- 239000012528 membrane Substances 0.000 title claims abstract description 106
- 229920001780 ECTFE Polymers 0.000 title claims abstract description 46
- -1 ethylene-chlorotrifluoroethylene Chemical class 0.000 title claims abstract description 34
- 238000002360 preparation method Methods 0.000 title claims abstract description 10
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 54
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims abstract description 28
- 239000004372 Polyvinyl alcohol Substances 0.000 claims abstract description 19
- 239000003995 emulsifying agent Substances 0.000 claims abstract description 19
- 229920002451 polyvinyl alcohol Polymers 0.000 claims abstract description 19
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 14
- 238000000576 coating method Methods 0.000 claims abstract description 13
- 239000011248 coating agent Substances 0.000 claims abstract description 12
- 238000001035 drying Methods 0.000 claims abstract description 5
- 239000000203 mixture Substances 0.000 claims abstract description 3
- 238000000034 method Methods 0.000 claims description 8
- 238000004519 manufacturing process Methods 0.000 claims description 5
- 239000002994 raw material Substances 0.000 claims description 4
- BCKXLBQYZLBQEK-KVVVOXFISA-M Sodium oleate Chemical compound [Na+].CCCCCCCC\C=C/CCCCCCCC([O-])=O BCKXLBQYZLBQEK-KVVVOXFISA-M 0.000 claims description 3
- 230000008569 process Effects 0.000 claims description 3
- 229920003171 Poly (ethylene oxide) Polymers 0.000 claims description 2
- 229920001213 Polysorbate 20 Polymers 0.000 claims description 2
- 238000006136 alcoholysis reaction Methods 0.000 claims description 2
- 239000000956 alloy Substances 0.000 claims description 2
- 229910045601 alloy Inorganic materials 0.000 claims description 2
- 239000004359 castor oil Substances 0.000 claims description 2
- 235000019438 castor oil Nutrition 0.000 claims description 2
- ZEMPKEQAKRGZGQ-XOQCFJPHSA-N glycerol triricinoleate Natural products CCCCCC[C@@H](O)CC=CCCCCCCCC(=O)OC[C@@H](COC(=O)CCCCCCCC=CC[C@@H](O)CCCCCC)OC(=O)CCCCCCCC=CC[C@H](O)CCCCCC ZEMPKEQAKRGZGQ-XOQCFJPHSA-N 0.000 claims description 2
- 239000012510 hollow fiber Substances 0.000 claims description 2
- 239000000256 polyoxyethylene sorbitan monolaurate Substances 0.000 claims description 2
- 235000010486 polyoxyethylene sorbitan monolaurate Nutrition 0.000 claims description 2
- CHJAYYWUZLWNSQ-UHFFFAOYSA-N 1-chloro-1,2,2-trifluoroethene;ethene Chemical group C=C.FC(F)=C(F)Cl CHJAYYWUZLWNSQ-UHFFFAOYSA-N 0.000 claims 1
- 238000009472 formulation Methods 0.000 claims 1
- 238000007654 immersion Methods 0.000 claims 1
- 238000012986 modification Methods 0.000 abstract description 32
- 230000004048 modification Effects 0.000 abstract description 32
- 238000000926 separation method Methods 0.000 abstract description 9
- 230000004907 flux Effects 0.000 abstract description 7
- 238000007598 dipping method Methods 0.000 abstract description 5
- 239000011148 porous material Substances 0.000 description 12
- 230000003247 decreasing effect Effects 0.000 description 8
- 230000000052 comparative effect Effects 0.000 description 7
- 230000000694 effects Effects 0.000 description 7
- 238000002156 mixing Methods 0.000 description 7
- 238000002715 modification method Methods 0.000 description 7
- 238000002791 soaking Methods 0.000 description 6
- 239000000126 substance Substances 0.000 description 6
- 238000009826 distribution Methods 0.000 description 5
- 239000000463 material Substances 0.000 description 5
- 230000008859 change Effects 0.000 description 4
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 description 3
- 230000008901 benefit Effects 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 229910052731 fluorine Inorganic materials 0.000 description 3
- 239000011737 fluorine Substances 0.000 description 3
- 238000001878 scanning electron micrograph Methods 0.000 description 3
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 description 2
- 239000005977 Ethylene Substances 0.000 description 2
- 229920007925 Ethylene chlorotrifluoroethylene (ECTFE) Polymers 0.000 description 2
- 239000002033 PVDF binder Substances 0.000 description 2
- 230000002411 adverse Effects 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- UUAGAQFQZIEFAH-UHFFFAOYSA-N chlorotrifluoroethylene Chemical group FC(F)=C(F)Cl UUAGAQFQZIEFAH-UHFFFAOYSA-N 0.000 description 2
- 238000002329 infrared spectrum Methods 0.000 description 2
- 238000001471 micro-filtration Methods 0.000 description 2
- 229920001343 polytetrafluoroethylene Polymers 0.000 description 2
- 239000004810 polytetrafluoroethylene Substances 0.000 description 2
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 2
- 239000002904 solvent Substances 0.000 description 2
- 239000004094 surface-active agent Substances 0.000 description 2
- NKSOSPOXQKNIKJ-CLFAGFIQSA-N Polyoxyethylene dioleate Polymers CCCCCCCC\C=C/CCCCCCCC(=O)OCCOC(=O)CCCCCCC\C=C/CCCCCCCC NKSOSPOXQKNIKJ-CLFAGFIQSA-N 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 238000007605 air drying Methods 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 229920005603 alternating copolymer Polymers 0.000 description 1
- 238000005266 casting Methods 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 239000003085 diluting agent Substances 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 239000012456 homogeneous solution Substances 0.000 description 1
- 229920001477 hydrophilic polymer Polymers 0.000 description 1
- 238000000643 oven drying Methods 0.000 description 1
- 230000035699 permeability Effects 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 238000004528 spin coating Methods 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
- 230000007480 spreading Effects 0.000 description 1
- 238000003892 spreading Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
- 238000000108 ultra-filtration Methods 0.000 description 1
Images
Classifications
-
- 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
- B01D67/0081—After-treatment of organic or inorganic membranes
- B01D67/0093—Chemical modification
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
- B01D61/14—Ultrafiltration; Microfiltration
- B01D61/145—Ultrafiltration
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
- B01D69/08—Hollow fibre membranes
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2323/00—Details relating to membrane preparation
- B01D2323/02—Hydrophilization
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2323/00—Details relating to membrane preparation
- B01D2323/12—Specific ratios of components used
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2323/00—Details relating to membrane preparation
- B01D2323/28—Pore treatments
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2323/00—Details relating to membrane preparation
- B01D2323/46—Impregnation
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2325/00—Details relating to properties of membranes
- B01D2325/36—Hydrophilic membranes
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Water Supply & Treatment (AREA)
- Inorganic Chemistry (AREA)
- Manufacturing & Machinery (AREA)
- Separation Using Semi-Permeable Membranes (AREA)
Abstract
The invention relates to a hydrophilic agent, a modified ethylene-chlorotrifluoroethylene membrane and a preparation method thereof. A hydrophilic agent mainly comprises the following components: according to weight percentage, 3 to 50 percent of polyvinyl alcohol, 0.5 to 15 percent of O/W type emulsifier, 30 to 50 percent of ethanol and 10 to 60 percent of water. The modified ethylene-chlorotrifluoroethylene membrane is obtained by coating or impregnating the surface of the ethylene-chlorotrifluoroethylene membrane with the above-mentioned hydrophilic agent, and then drying. The invention can realize the hydrophilic modification of the ethylene-chlorotrifluoroethylene membrane by using the hydrophilic agent with simple composition, adopts the means of dipping or coating, and can fully keep the self excellent characteristics of the porosity, the membrane flux, the separation precision and the like of the membrane.
Description
Technical Field
The invention relates to the field of membrane materials, in particular to a hydrophilic agent, a modified ethylene-chlorotrifluoroethylene membrane and a preparation method thereof.
Background
In the preparation process of the separation membrane, the selection of the membrane-forming polymer which has excellent permeability, thermal stability and chemical stability and is easy to process and form is the most important link. Ethylene-chlorotrifluoroethylene (ECTFE) is an alternating copolymer of ethylene and chlorotrifluoroethylene, combines the performance advantages of ethylene and chlorotrifluoroethylene, has better strong alkali and strong acid resistance, high temperature resistance and strong chemical corrosion resistance than polyvinylidene fluoride (PVDF), and has better processability than Polytetrafluoroethylene (PTFE). Therefore, the value of ECTFE in preparing high performance microporous membranes for use in industrial processes such as membrane separation is of great interest.
At present, the research on the ECTFE microfiltration membrane in China is in an initial stage, and the research on the hydrophilization modification of the ECTFE microfiltration membrane is not reported. There are many hydrophilic modification methods for membrane materials, and the hydrophilic modification methods in practical application mainly include graft modification, blending modification, surface coating modification and the like. The blending modification is to blend the film forming material and hydrophilic substance, and add additive to form film casting solution, after film forming, the hydrophilic substance forms film component to increase the hydrophilicity of the film. The graft modification is to graft hydrophilic groups onto a membrane substrate by chemical reaction or physical means, and usually by chemical bonding, the hydrophilicity of the membrane can be maintained for a long period of time. The surface coating modification is to coat a dilute solution of hydrophilic substance on the surface of the membrane by dipping, spraying or spin coating, etc., so as to form a new hydrophilic layer on the surface of the membrane. The blending process can cause certain influence on the porosity of the membrane, thereby influencing the membrane flux, the separation precision and the like; ECTFE is chemically inert and is not easy to hydrophilize by a grafting method; the coating modification has strong operability and small influence on the membrane structure, but no report exists at present for using the hydrophilic agent as the ECTFE coating hydrophilic modification.
Disclosure of Invention
The first purpose of the present invention is to provide a hydrophilizing agent for use in surface coating modification of an Ethylene Chlorotrifluoroethylene (ECTFE) membrane, which can improve the hydrophilicity of the membrane and can avoid adverse effects on the porosity of the membrane itself, the membrane flux, and the separation accuracy.
The second purpose of the invention is to provide the preparation method of the hydrophilic agent, which is simple and can be used for mixing all the raw materials uniformly, thus bringing great convenience for the existing preparation of the hydrophilic agent.
The third purpose of the invention is to provide a preparation method of a modified ethylene-chlorotrifluoroethylene membrane, which takes the hydrophilic agent as a modification solution and adopts a coating or dipping means to modify the membrane, thereby not only not influencing the existing ECTFE production process, but also improving the hydrophilicity of the membrane and simultaneously avoiding the adverse influence on the porosity, membrane flux and separation precision of the membrane.
A fourth object of the present invention is to provide a modified ethylene-chlorotrifluoroethylene membrane having both good hydrophilicity and good porosity, membrane flux and separation accuracy.
In order to achieve the above purpose, the invention provides the following technical scheme:
a hydrophilic agent mainly comprises the following components: according to the weight percentage, the weight percentage of the alloy is,
3-50 wt% of polyvinyl alcohol (PVA),
0.5 to 15 percent of O/W type emulsifier,
30-50 wt% of ethanol,
and water 10-60 wt%.
The hydrophilic agent can be used for modifying the surface of a membrane, improving the hydrophilicity of the membrane, and can be used for hydrophilic modification of various filter membranes, such as hydrophilic modification of fluorine-containing material ultramicro filter membranes, wherein the effect is most remarkable particularly for ethylene-chlorotrifluoroethylene membranes, and the hydrophilic agent is different from the existing hydrophilic agent in that the hydrophilic agent can also show the following characteristics besides improving the hydrophilicity: the ethylene-chlorotrifluoroethylene membrane has firm adhesion on the surface, and is favorable for maintaining the membrane flux, the separation precision and the porosity before modification.
Wherein, polyvinyl alcohol is used as a hydrophilic polymer as a main functional component for improving hydrophilicity. The O/W emulsifier is used for improving the surface activity, the HLB value is usually 8-18, which is beneficial to the uniformity of the hydrophilic agent, ensures that the surface tension of the hydrophilic agent is matched with the surface tension of the ethylene-chlorotrifluoroethylene film, and is beneficial to the uniform spreading of the hydrophilic agent on the film surface, thereby easily modifying the film surface and improving the hydrophilicity. Water and ethanol as solvent/diluent not only facilitate the dissolution of the emulsifier with the polyvinyl alcohol, but also are easily dried off after coating.
The content of each raw material in the hydrophilizing agent described in the present invention may take any value within the above range, for example, the content of polyvinyl alcohol may take the following values, but is not limited thereto: 3%, 5%, 7%, 10%, 12%, 15%, 17%, 20%, 22%, 25%, 27%, 30%, 32%, 35%, 37%, 40%, 42%, 45%, 47%, 50%, etc.
The content of the O/W type emulsifier may take the following values, but is not limited thereto: 0.5%, 1.0%, 2.0%, 3%, 4%, 5%, 7%, 9%, 10%, 12%, 15%, etc.
The content of ethanol may take the following values, but is not limited to: 30%, 32%, 35%, 37%, 40%, 42%, 45%, 47%, 50%, etc.
The water content may take, but is not limited to, the following values: 10%, 12%, 15%, 17%, 20%, 22%, 25%, 27%, 30%, 32%, 35%, 37%, 40%, 42%, 45%, 47%, 50%, 52%, 55%, 57%, 60%, etc.
Within the above range, the range in which the hydrophilicity of the ethylene-chlorotrifluoroethylene membrane is more significantly improved is as follows:
preferably, the amount of the surfactant is, in weight percent,
10 to 20 percent of polyvinyl alcohol,
0.5 to 15%, preferably 5 to 10%,
30-45 wt% of ethanol,
and 20-45% of water.
The HLB value of the O/W type emulsifier is lower than 8, and the solubility of the O/W type emulsifier in a hydrophilic agent solution is reduced; the HLB value is higher than 18, and the action of the surfactant is lowered, preferably in the range of 8 to 18, more preferably 13 to 15.
The O/W type emulsifier is at least one of polyoxyethylene monolaurate, polyoxyethylene castor oil, sodium oleate, polyoxyethylene sorbitan monolaurate and polyoxyethylene monostearate, including but not limited to polyoxyethylene monostearate with HLB of 14.
Preferably, the degree of alcoholysis of the polyvinyl alcohol is from 87 to 100%, preferably from 98 to 100%. The hydrophilic agent can reduce the contact angle of the film and improve the hydrophilicity.
Preferably, the polyvinyl alcohol has a molecular weight of from 2 to 16, preferably from 4 to 9, ten thousand. The hydrophilic agent can reduce the contact angle of the film and improve the hydrophilicity.
The preparation method of the hydrophilic agent is simple, the raw materials are only required to be uniformly mixed, the mixing sequence is arbitrary, preferably, ethanol, water and an emulsifier are firstly mixed, an O/W type solution environment is prepared in advance, and then the hydrophilic agent is added and uniformly mixed.
The method for modifying the ethylene-chlorotrifluoroethylene membrane by using the hydrophilic agent is simple and comprises the following steps:
and (3) coating or soaking the surface of the ethylene-chlorotrifluoroethylene membrane with the hydrophilic agent, and drying to obtain the modified ethylene-chlorotrifluoroethylene membrane.
Wherein, after coating or dipping, the hydrophilic agent is kept for a period of time to uniformly penetrate into the surface and the interior of the film, and the keeping time is preferably more than 24 hours.
The means of drying is arbitrary, such as typical oven drying or air drying.
Therefore, compared with the existing blending method and grafting method, the invention does not interfere with the production process of the ethylene-chlorotrifluoroethylene membrane, and directly and physically modifies the produced ethylene-chlorotrifluoroethylene membrane, thereby greatly reducing the difficulty of upgrading the product.
In addition, the hydrophilic agent of the present invention is suitable for modification of membranes constructed in various shapes, such as common typical hollow fiber membranes.
The hydrophilizing agent and the modification method thereof according to the present invention are also used for hydrophilizing other fluorine-containing ultrafiltration membranes, and are not limited to the above-mentioned ethylene-chlorotrifluoroethylene membranes.
In summary, compared with the prior art, the invention achieves the following technical effects:
(1) the hydrophilic modification of the fluorine-containing material ultramicro filtration membrane such as an ethylene-chlorotrifluoroethylene membrane can be realized by utilizing a hydrophilic agent with simple composition, and the self excellent characteristics of the porosity, the membrane flux, the separation precision and the like of the membrane can be fully reserved by adopting a dipping or coating method.
Drawings
Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention. Also, like reference numerals are used to refer to like parts throughout the drawings.
FIG. 1 is a graph showing the dynamic contact angle change in a membrane 30s after modification in example 1 of the present invention;
FIG. 2 is a diagram showing the pore size distribution of the modified membrane of example 1;
FIGS. 3 and 4 are scanning electron micrographs of cross sections of films modified in example 1 of the present invention;
FIGS. 5 and 6 are scanning electron micrographs of the inner surface of the film after modification in example 1 of the present invention;
FIGS. 7 and 8 are SEM photographs of the outer surface of the modified film in example 1 of the present invention
FIG. 9 is the dynamic contact angle change in a membrane 30s after modification in example 2 of the present invention;
FIG. 10 is a modified membrane pore size distribution diagram of example 2 of the present invention;
fig. 11 is the dynamic contact angle change in ECTFE membrane 30s after treatment of comparative example 1;
FIG. 12 is a graph of the pore size distribution of ECTFE membrane after treatment of comparative example 1;
fig. 13 is the dynamic contact angle change in ECTFE membrane 30s after treatment of comparative example 2;
FIG. 14 is a graph of the pore size distribution of ECTFE membrane treated in comparative example 2;
FIG. 15 is an infrared spectrum of ECTFE membrane treated in comparative example 2;
Detailed Description
Embodiments of the present invention will be described in detail below with reference to examples, but it will be understood by those skilled in the art that the following examples are only illustrative of the present invention and should not be construed as limiting the scope of the present invention. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.
Example 1
80g of ethanol, 80g of water and 20g of emulsifier (polyoxyethylene monostearate, HLB value of 14) are mixed, 20g of PVA (16-99) is added and stirred uniformly to form a uniform hydrophilic agent solution. And (3) soaking the dried ECTFE membrane filaments in the prepared hydrophilic agent solution for 24 hours, and naturally airing the membrane filaments. Fig. 1 shows the dynamic contact angle of the resulting membrane filaments in 30s, decreasing from 97.2 ° to 24.4 °. It can be seen that the hydrophilic performance of the membrane is significantly enhanced after the emulsifier is introduced. The mode pore size of the membrane after modification in fig. 2 was reduced to 215nm compared to the mode pore size 291nm of the membrane before modification in fig. 12. Scanning electron micrographs of the modified film are shown in FIGS. 3 to 8.
Example 2
80g of ethanol, 80g of water and 20g of emulsifier sodium oleate (the HLB value is 20) are mixed, 20g of PVA (16-99) is added and stirred uniformly to form a uniform hydrophilic agent solution. And (3) soaking the dried ECTFE membrane filaments in the prepared hydrophilic agent solution for 24 hours, and naturally airing the membrane filaments. Fig. 9 shows the dynamic contact angle of the resulting membrane filaments in 30s, decreasing from 96.3 ° to 47.5 °. Although the hydrophilicity is enhanced, the hydrophilicity is not as good as the modification effect of a hydrophilic agent solution prepared by using an emulsifier having an HLB value of 14. As shown in fig. 10, the mode pore size of the modified membrane was reduced to 233 nm.
Example 3
80g of ethanol, 80g of water and 20g of emulsifier polyoxyethylene dioleate (HLB value is 7.5) are mixed, 20g of PVA (16-99) is added and stirred uniformly to form a uniform hydrophilic agent solution. And (3) soaking the dried ECTFE membrane filaments in the prepared hydrophilic agent solution for 24 hours, and naturally airing the membrane filaments. The dynamic contact angle in the obtained membrane silk 30s is reduced from 96.3 degrees to 60.5 degrees. Although the hydrophilicity is enhanced, the hydrophilicity is not as good as the modification effect of a hydrophilic agent solution prepared by using an emulsifier having an HLB value of 14. The most probable pore diameter of the modified membrane is reduced to 237 nm.
Examples 4 to 7
The difference from example 1 is the content of each component in the hydrophilic agent solution, as shown in table 1, wherein the percentages refer to weight percentage.
| Examples | PVA content% | Emulsifier% | Ethanol | Water% | |
| 4 | 3 | 0.5 | 36.5 | 60 | |
| 5 | 10 | 5 | 45 | 40 | |
| 6 | 20 | 15 | 50 | 15 | |
| 7 | 50 | 10 | 30 | 10 |
The effect of the hydrophilic solvent on the membrane modification is as follows:
after modification of ECTFE membrane filaments with the hydrophilizing agent solution of example 4 (same modification method as in example 1), the dynamic contact angle of the resulting membrane filaments within 30s decreased from 96.1 ° to 67.5 °.
After modification of ECTFE membrane filaments with the hydrophilizing agent solution of example 5 (same modification method as in example 1), the dynamic contact angle of the resulting membrane filaments within 30s decreased from 96.4 ° to 35.8 °.
After modification of ECTFE membrane filaments with the hydrophilizing agent solution of example 6 (same modification method as in example 1), the dynamic contact angle of the resulting membrane filaments within 30s decreased from 96.2 ° to 51.7 °.
After modification of ECTFE membrane filaments with the hydrophilizing agent solution of example 7 (same modification method as in example 1), the dynamic contact angle of the resulting membrane filaments within 30s decreased from 96.3 ° to 48.2 °.
Comparative example 1
100g of ethanol and 100g of water were stirred well to form a homogeneous solution. And (3) soaking the dried ECTFE membrane filaments in the prepared solution for 24 hours, and naturally airing the membrane filaments. FIG. 11 shows the dynamic contact angle of the resulting membrane filaments in 30s, decreasing from 96.4 to 73.2. The ECTFE membrane in fig. 12 had a diameter of 291nm as the most probable pore diameter.
Comparative example 2
After mixing 90g of ethanol and 90g of water, 20g of PVA (16-99) was added and stirred uniformly to form a homogeneous hydrophilizing agent solution. And (3) soaking the dried ECTFE membrane filaments in the prepared solution for 24 hours, and naturally airing the membrane filaments. FIG. 13 shows the contact angle of the resulting membrane filaments decreasing from 96.3 to 4 within 30 seconds1.8 degrees. Compared with the membrane before modification, the hydrophilic performance of the membrane is obviously enhanced after the hydrophilic agent is introduced. Fig. 14 is a distribution diagram of the membrane pore size after modification, with a mode pore size of 239nm, which is significantly smaller than the membrane pore size before modification. FIG. 15 is a membrane filament infrared spectrum at 1750cm-1Has a-C ═ O stretching vibration peak at 3400cm-1Can see a wider-OH peak at 1250cm-1The peak of-C-O-stretching vibration appears. Therefore, it was confirmed that PVA was successfully coated on the ECTFE membrane surface.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the appended claims.
Claims (10)
1. A hydrophilic agent is characterized by mainly comprising the following components: according to the weight percentage, the weight percentage of the alloy is,
3-50 wt% of polyvinyl alcohol,
0.5 to 15 percent of O/W type emulsifier,
30-50 wt% of ethanol,
and water 10-60 wt%.
2. Hydrophilizing agent according to claim 1, characterized in that, in weight percent,
10 to 20 percent of polyvinyl alcohol,
0.5 to 15%, preferably 5 to 10%,
30-45 wt% of ethanol,
and 20-45% of water.
3. Hydrophilic agent according to claim 1, characterized in that the emulsifier of the O/W type has an HLB value of 8 to 18, preferably 13 to 15.
4. Hydrophilic agent according to any of claims 1-3, wherein the O/W emulsifier is at least one of polyoxyethylene monolaurate, polyoxyethylene castor oil, sodium oleate, polyoxyethylene sorbitan monolaurate and polyoxyethylene monostearate.
5. Hydrophilic agent according to any of claims 1 to 3, wherein the degree of alcoholysis of the polyvinyl alcohol is 87 to 100%, preferably 98 to 100%.
6. A hydrophilic agent as claimed in any one of claims 1 to 3, wherein the polyvinyl alcohol has a molecular weight of from 2 to 16, preferably from 4 to 9, ten thousand.
7. A process for the preparation of a hydrophilic agent as claimed in any one of claims 1 to 6, wherein all the raw materials are mixed according to a formulation.
8. A method for preparing a modified ethylene-chlorotrifluoroethylene membrane, comprising:
the modified ethylene-chlorotrifluoroethylene membrane is obtained by coating or impregnating the surface of an ethylene-chlorotrifluoroethylene membrane with the hydrophilic agent according to any one of claims 1 to 6, and then drying the coated or impregnated ethylene-chlorotrifluoroethylene membrane.
9. The production method according to claim 8, wherein the time for the immersion is 24 hours or more;
preferably, the drying mode is airing.
10. A modified ethylene chlorotrifluoroethylene membrane, preferably a hollow fiber membrane, produced by the production method according to claim 8 or 9.
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| CN1221649A (en) * | 1998-12-11 | 1999-07-07 | 清华大学 | Method for prepn. of permeation vaporization compound membrane |
| CN1276262A (en) * | 1999-06-08 | 2000-12-13 | 中国科学院生态环境研究中心 | Process and special equipment for preparing anti-pollution compound plyvinyl alcohol film |
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| CN109219474A (en) * | 2016-06-02 | 2019-01-15 | 阿莫绿色技术有限公司 | Filter medium, its manufacturing method and the filter module including it |
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