CN114259877B - Preparation method of PVC/EVOH binary blending flat ultrafiltration membrane with sponge pore structure - Google Patents
Preparation method of PVC/EVOH binary blending flat ultrafiltration membrane with sponge pore structure Download PDFInfo
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Abstract
The invention discloses a preparation method of a PVC/EVOH binary blending flat ultrafiltration membrane with a sponge pore structure, which is characterized in that water-soluble esters are used as a diluent, water-soluble alcohol is used as a non-diluent, a composite phase conversion method is adopted to prepare a porous membrane, the thermal phase process of the porous membrane is regulated and controlled by regulating the composition and content of the diluent, the non-diluent and a solvent and controlling the residence time of a casting membrane liquid in the air, so that the casting membrane liquid is subjected to heat exchange to be gelatinized, the viscosity of the casting membrane liquid is infinitely increased, the membrane shape is rapidly fixed, and the non-solvent phase process is combined, so that the membrane structure is effectively changed from finger-shaped pores to sponge pores, a full sponge pore structure is obtained, and the membrane pore connectivity and the mechanical property are obviously improved; the flat membrane prepared by the method has the advantages of high mechanical strength, good compression resistance, low operation temperature, simple process, no pollution and low cost, and is suitable for popularization and use.
Description
Technical Field
The invention relates to the technical field of membrane separation, in particular to a preparation method of a PVC/EVOH binary blending flat ultrafiltration membrane with a sponge pore structure.
Background
The membrane separation technology is a novel separation technology, and a separation membrane with excellent performance should have high flux, high retention rate (or high separation coefficient), sufficient toughness and mechanical strength, excellent hydrophilicity and the like. Polyvinyl chloride has rich sources and low price, can greatly reduce the cost of the membrane as a membrane material, simultaneously has the advantages of chemical resistance, acid and alkali resistance, microorganism corrosion resistance and the like, and is a membrane material with economic benefit. Compared with other commercial separation membranes, although some polyvinyl chloride ultrafiltration membranes, microfiltration membranes and ion exchange membranes are commercialized, the membrane structure is mostly finger-shaped or macroporous, so that the membrane strength is poor, and the membrane is compacted under the condition of long-term transmembrane pressure difference to remarkably reduce the flux. Therefore, the method has important practical significance for improving the mechanical property of the PVC ultrafiltration membrane by controlling the membrane pore structure. The sponge pore structure is used as an important component of the separation membrane structure, and has the characteristics of uniform shape, good support strength and small membrane pore collapse degree in the drying process, so that the PVC ultrafiltration membrane with the sponge pore structure becomes a development hotspot in the field.
There are various methods for preparing PVC ultrafiltration membranes, among which the phase inversion method is one of the most common methods, and is mainly to control the liquid-liquid or solid-liquid phase separation phase inversion of a polymer solution to prepare a membrane, and the methods may be classified into a non-solvent induced phase separation method, a thermally induced phase separation method, and the like according to the phase separation method.
At present, a commercial method for preparing the PVC ultrafiltration membrane is a non-solvent induced phase separation method (NIPS), however, the PVC membrane structure obtained by the method is a composite structure formed by a skin layer with a certain thickness and a finger-shaped hole supporting layer, the mechanical strength of the membrane is not enough, the compression resistance is poor, and the opening of the surface of the membrane is difficult, and the problems limit the application depth and the application range to a certain extent. The membrane obtained by the thermally induced phase separation method (TIPS) has great advantages in regulating and controlling the structure, the structure of a membrane supporting layer can be regulated and controlled into a uniform sponge pore structure, the porosity and the mechanical property of the membrane can be improved, but the temperature required by the method in the membrane preparation process is higher, and PVC has the possibility of decomposition at high temperature. However, the two membrane preparation processes of the thermally induced phase separation method and the non-solvent induced phase separation method are combined, so that the advantages of a single process can be exerted, the effects of the two processes can be exerted to the maximum, the problem that the requirement on temperature in the TIPS method is too high is solved, the problems that the membrane obtained in the NIPS method is poor in pressure resistance and difficult in surface opening are solved, and meanwhile, the structure and the performance of the membrane can be controlled according to the parameters of the membrane preparation process.
The Chinese patent application with the publication number of CN106606932A discloses a preparation method for controlling the pore structure of a polyvinyl chloride (PVC) ultrafiltration membrane at low cost. The viscosity of the casting solution is improved by adding a large amount of PEG, so that the exchange rate between the solvent and water is reduced, the precipitation rate is slowed, and a sponge-like structure is finally formed due to the slow phase separation process of a sub-layer in the section. The preparation process of the membrane is simple, but the obtained sponge Kong Duowei is closed, and essentially belongs to a non-solvent phase-induced technology.
Chinese patent application with publication number CN111266016A discloses a preparation method of a separation membrane with a spongy structure and adjustable pore diameter and a separation membrane prepared by the preparation method. By controlling air humidity, temperature and residence time, the casting solution volatilizes and absorbs water vapor phase-splitting gel through a solvent or a non-solvent under the condition of certain temperature and humidity, polymer deposition is induced along with the evaporation of the solvent in the film forming process so as to form a uniform microporous structure, and the precise regulation and control of the membrane aperture are realized by controlling the composition of the casting solution and the treatment condition of the vapor phase-splitting gel. The method requires high air humidity, high air temperature, large process energy consumption, is tedious and difficult to produce on a large scale, and the membrane prepared by the method has very large aperture and low filtration precision, and essentially still belongs to a non-solvent induced phase technology.
Chinese patent application publication No. CN101890307a discloses a polyvinylidene fluoride hollow fiber membrane with gradient density and a preparation method thereof. The method is characterized in that a curing temperature gradient difference is formed by controlling the residence time of a casting solution in the air, and a polyvinylidene fluoride hollow fiber membrane with a gradient pore structure is prepared by adopting a thermally induced phase separation method. The method has relatively high energy consumption and complex process control.
The Chinese patent application with the publication number of CN104415671B discloses a method for preparing a polyvinylidene fluoride alloy film by a composite thermally induced phase separation method, caprolactam is used as a solvent, the solvent is single, the required dissolving temperature is high, and the obtained network structure forms a spherulite stacking state.
Disclosure of Invention
The invention aims to provide a preparation method of a PVC/EVOH binary blending flat ultrafiltration membrane with a sponge pore structure aiming at the defects of the prior art, and the PVC/EVOH binary blending flat ultrafiltration membrane with a full sponge pore structure can be prepared at low cost. The method is characterized in that a composite phase conversion method is adopted, the air retention time is properly prolonged by adjusting the proportion of a solvent and a diluent and the proportion of the diluent and a non-diluent, the temperature reduction process is controlled, so that a casting film liquid system is subjected to heat exchange to be gelatinized, the viscosity of the casting film liquid system is infinitely increased, the film shape is rapidly fixed, and after the casting film liquid system enters a coagulating bath, the phase-inducing process is combined with a non-solvent, the exchange rate of the solvent and water is reduced, and the PVC/EVOH binary blending flat ultrafiltration membrane with the full-sponge pore structure section can be controllably obtained.
The technical scheme adopted by the invention for solving the technical problems is as follows:
a preparation method of a PVC/EVOH binary blending flat ultrafiltration membrane with a sponge pore structure comprises the following steps:
1) Preparing a casting solution: weighing polyvinyl chloride (PVC), a diluent, a non-diluent, a solvent and ethylene-vinyl alcohol copolymer (EVOH) according to a formula of the casting solution, mixing, heating to 20-100 ℃, stirring for 1-12h, and standing for defoaming completely to obtain the casting solution;
2) Scraping: at room temperature, the casting solution is scraped and coated on non-woven fabric at the speed of 0.1-5 m/s to prepare a membrane, and the membrane stays in the air for 10-240s;
3) And (3) curing: immersing the membrane into a coagulating bath to be solidified into a membrane;
4) Soaking: and soaking the cured film in deionized water for more than 48 hours for later use.
The formula amount of the casting solution is as follows by mass fraction: 10-25% of polyvinyl chloride, 8-50% of diluent, 2-10% of non-diluent, 25-65% of solvent and 1-5% of ethylene-vinyl alcohol copolymer.
Further, the mass ratio of the solvent to the diluent in the casting solution is 1.
Furthermore, the mass ratio of the diluent to the non-diluent in the casting solution is 3:1-10.
The non-woven fabric is any one of polyethylene terephthalate or polyamide non-woven fabric, and the thickness of the non-woven fabric is 50-150 mu m.
The diluent is a water-soluble ester with poor solubility with the polymer and high boiling point.
Preferably, the diluent is a water-soluble ester which has poor solubility with PVC and a boiling point higher than that of the solvent.
More preferably, it is one of γ -butyrolactone, ethylene carbonate, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, propylene glycol monoethyl ether acetate, and dipropylene glycol monoethyl ether acetate.
Preferably, the non-diluent is water-soluble polyethylene glycol (PEG); the non-diluent of the invention adopts water-soluble PEG, which has the characteristics of dissolving in the diluent at high temperature and cooling to be in a phase-separated state with the diluent.
Preferably, the polyethylene glycol has a molecular weight of 200g/mol, 400g/mol, 600g/mol, 800g/mol, 1000g/mol, 1500g/mol, 2000g/mol, 4000g/mol, 6000g/mol, 8000g/mol, 10000g/mol, 20000 g/mol.
Preferably, the solvent is one of N, N-dimethylformamide, N-dimethylacetamide, N-methylpyrrolidone, triethyl phosphate, trimethyl phosphate and dimethyl sulfoxide.
Preferably, the thickness of the membrane sheet in the step 2) is 20 to 300 μm.
Preferably, the coagulation bath in step 3) is water.
The preparation method of the PVC/EVOH binary blending flat ultrafiltration membrane with the sponge pore structure comprises the following steps:
1) Preparing a casting solution: weighing polyvinyl chloride, ethylene-vinyl alcohol copolymer, diluent, non-diluent and solvent according to the formula of the casting solution, mixing, heating to 90-100 ℃, stirring for 1-12h, and standing and defoaming completely to obtain the casting solution;
2) Scraping: at room temperature, the casting solution is coated on non-woven fabric at the speed of 0.1-5 m/s to prepare a membrane and the membrane stays in the air for 30-60s;
3) And (3) curing: soaking the membrane into a water coagulation bath to be solidified into a membrane;
4) Soaking: soaking the cured film in deionized water for 48h for later use;
the formula amount of the casting solution is as follows by mass fraction: 14-20% of polyvinyl chloride, 20-45% of diluent, 2-10% of non-diluent, 26-55% of solvent and 1-5% of ethylene-vinyl alcohol copolymer; the mass ratio of the solvent to the diluent in the casting solution is 1:2-3:1, and the mass ratio of the diluent to the non-diluent in the casting solution is 3:1-6:1.
Has the advantages that:
the invention prepares the PVC/EVOH binary blending flat ultrafiltration membrane by a composite phase inversion method, adopts the combination of water-soluble diluent, non-diluent and solvent to reduce the dissolution temperature, and properly prolongs the air retention time, controls the cooling process and regulates and controls the thermotropic phase process in the membrane preparation process, thereby achieving the purpose of regulating and controlling the pore structure. According to the invention, by utilizing the characteristics of poor solubility of the diluent and PVC, high-temperature dissolution and low-temperature phase separation between the diluent and PVC, the casting solution is subjected to phase separation and gelation in the cooling process, the viscosity of the casting solution system is infinitely increased, the film shape is rapidly fixed, and after the casting solution enters a coagulation bath, the phase-inducing process of a non-solvent is combined, the exchange rate of the solvent and water is reduced, and the PVC/EVOH binary blending flat ultrafiltration membrane with the full-sponge pore structure section can be obtained in a controllable manner.
The invention introduces the second blend EVOH with weaker acting force with the diluent, and the existence of the non-diluent can reduce the interacting force of the diluent and the polymer, so that the temperature of the formed polymer solution is increased, and the gelation rate of the casting solution in the cooling process can be accelerated. The polymer solution is subjected to phase separation in the cooling process to enable the system to be gelatinized, so that the viscosity of the system is obviously increased, the influence of subsequent non-solvent induced phase double-diffusion mass transfer to generate finger-shaped holes is effectively inhibited, the influence of the non-solvent induced phase process on the membrane structure can be effectively inhibited, and the formation of a sponge hole structure is facilitated.
In addition, in the phase-induced non-solvent process, the exchange speed of the diluent and the non-solvent water is gradually increased in the heat transfer process, so that the crystallization of the casting solution is further accelerated, and the surface opening of the film is facilitated. The PVC/EVOH binary blending flat ultrafiltration membrane with a through sponge pore structure and a surface porous structure can be prepared under the combined action of the thermally induced phase separation process and the non-solvent induced phase separation process, the problems of poor compression resistance and difficult surface opening of the membrane obtained by the non-solvent induced phase separation method are solved, and the structure and the performance of the membrane can be regulated and controlled according to the proportion and the content of a diluent, a non-diluent and a solvent and the air retention time.
The invention adopts the water-soluble ester as the diluent, so that water can be used as the coagulating bath, and further the film-making cost is reduced, the solvent is easy to recycle, and no pollution is caused to the environment.
The preparation method has the advantages of simplicity, easiness in implementation, wide material source, low manufacturing cost, low operation temperature, no pollution and convenience in actual production. The flat membrane prepared by the method has the characteristics of full sponge pore structure, membrane pore connectivity, high mechanical strength and good compression resistance.
Drawings
FIG. 1 is a cross-sectional structural view of a PVC/EVOH binary blended flat ultrafiltration membrane prepared in example 1;
FIG. 2 is a surface structure diagram of a PVC/EVOH binary blended flat ultrafiltration membrane prepared in example 1;
FIG. 3 is a cross-sectional structural view of a PVC/EVOH binary blended flat ultrafiltration membrane prepared in example 2;
FIG. 4 is a surface structure diagram of a PVC/EVOH binary blended flat ultrafiltration membrane prepared in example 2;
FIG. 5 is a cross-sectional structural view of a PVC/EVOH binary blended flat ultrafiltration membrane prepared in example 3;
FIG. 6 is a surface structure diagram of a PVC/EVOH binary blended flat ultrafiltration membrane prepared in example 3;
FIG. 7 is a cross-sectional structural view of a PVC/EVOH binary blended flat ultrafiltration membrane prepared in example 4;
FIG. 8 is a surface structure diagram of a PVC/EVOH binary blended flat ultrafiltration membrane prepared in example 4;
FIG. 9 is a cross-sectional structural view of a PVC/EVOH binary blended flat ultrafiltration membrane prepared in example 5;
FIG. 10 is a surface structure view of the PVC/EVOH binary blended flat ultrafiltration membrane prepared in example 5;
FIG. 11 is a cross-sectional structural view of the PVC/EVOH binary blended flat ultrafiltration membrane prepared in example 6;
FIG. 12 is a drawing of the surface structure of the PVC/EVOH binary blended flat ultrafiltration membrane prepared in example 6;
FIG. 13 is a cross-sectional structural view of a PVC/EVOH binary-blended flat ultrafiltration membrane prepared in comparative example 1;
FIG. 14 is a surface structure view of a PVC/EVOH binary blended flat ultrafiltration membrane prepared in comparative example 1;
FIG. 15 is a cross-sectional structural view of a PVC/EVOH binary-blended flat ultrafiltration membrane prepared in comparative example 2;
FIG. 16 is a surface structure view of a PVC/EVOH binary blended flat ultrafiltration membrane prepared in comparative example 2;
FIG. 17 is a partially enlarged cross-sectional structure view of the PVC/EVOH binary-blended flat ultrafiltration membrane prepared in example 1;
FIG. 18 is a partially enlarged cross-sectional structure view of the PVC/EVOH binary blended flat ultrafiltration membrane prepared in example 2;
FIG. 19 is a partially enlarged cross-sectional structure view of the PVC/EVOH binary blended flat ultrafiltration membrane prepared in example 3;
FIG. 20 is a partially enlarged cross-sectional structure view of the PVC/EVOH binary blended flat ultrafiltration membrane prepared in example 4;
FIG. 21 is a partially enlarged cross-sectional structure view of the PVC/EVOH binary-blended flat ultrafiltration membrane prepared in example 6.
Detailed Description
The following is a detailed description of the embodiments of the present invention, but the present invention is not limited to these embodiments, and any modifications or substitutions in the basic spirit of the embodiments are included in the scope of the present invention as claimed in the claims.
Example 1
A preparation method of a PVC/EVOH binary blending flat ultrafiltration membrane comprises the following steps:
step 1.1
Weighing the following raw materials in percentage by mass and mixing: 14% PVC,1% EVOH,36.5% ethylene glycol monomethyl ether acetate, 6% PEG200, 42.5% N, N-dimethylacetamide;
step 1.2
Heating the mixture obtained in the step 1.1 to 95 ℃, stirring to form a uniform transparent solution, and obtaining a membrane casting solution after the solution is defoamed completely;
At room temperature, scraping a membrane with the thickness of 300 microns on the surface of polyethylene glycol terephthalate non-woven fabric with the thickness of 100 microns by using the membrane casting solution at the speed of 1m/s, and staying in air for 30 seconds to prepare a flat membrane;
Putting the flat membrane into a 25 ℃ water coagulating bath for curing to form a membrane;
step 4 soaking
Taking out the membrane completely subjected to phase separation in the step 3, placing the membrane in deionized water for soaking for 48 hours, removing residual organic solvent in the membrane, taking out the membrane and drying the membrane in the air to obtain a PVC/EVOH binary blending flat ultrafiltration membrane;
FIG. 1 is a cross-sectional structural view of a PVC/EVOH binary-blended flat ultrafiltration membrane prepared in the present example;
FIG. 2 is a surface structure diagram of the PVC/EVOH binary-blended flat ultrafiltration membrane prepared in the embodiment.
Example 2
A preparation method of a PVC/EVOH binary blending flat ultrafiltration membrane comprises the following steps:
step 1.1
Weighing the following raw materials in percentage by mass and mixing: 15% PVC,1% EVOH,36% vinyl carbonate, 6% PEG400, 42% N-methylpyrrolidone;
step 1.2
Heating the mixture obtained in the step 1.1 to 95 ℃, stirring to form a uniform transparent solution, and obtaining a membrane casting solution after the solution is defoamed completely;
At room temperature, scraping a membrane with the thickness of 300 mu m on the surface of polyethylene glycol terephthalate non-woven fabric with the thickness of 100 mu m at the speed of 1m/s by using the membrane casting solution, and staying in air for 60s to prepare a flat membrane;
Putting the flat membrane into a 25 ℃ water coagulating bath for curing to form a membrane;
step 4 soaking
Taking out the membrane completely subjected to phase separation in the step 3, placing the membrane in deionized water for soaking for 48 hours, removing residual organic solvent in the membrane, taking out the membrane and drying the membrane in the air to obtain a PVC/EVOH binary blending flat ultrafiltration membrane;
FIG. 3 is a cross-sectional structural view of the PVC/EVOH binary-blended flat ultrafiltration membrane prepared in the present embodiment;
FIG. 4 is a surface structure diagram of the PVC/EVOH binary blending flat ultrafiltration membrane prepared in the embodiment.
Example 3
A preparation method of a PVC/EVOH binary blending flat ultrafiltration membrane comprises the following steps:
step 1.1
Weighing the following raw materials in percentage by mass and mixing: 16% PVC,1% EVOH,49.3% ethylene carbonate, 6% PEG600, 27.7% N-methylpyrrolidone;
step 1.2
Heating the mass of the mixture obtained in the step 1.1 to 100 ℃, stirring to form a uniform and transparent solution, and obtaining a membrane casting solution after the solution is defoamed completely;
Scraping a membrane with the thickness of 200 mu m on the surface of polyethylene glycol terephthalate non-woven fabric with the thickness of 100 mu m at the speed of 1m/s under the condition of room temperature, and staying in air for 30s to prepare a flat membrane, thus preparing the flat membrane;
Putting the flat membrane into a 25 ℃ water coagulating bath for curing to form a membrane;
step 4 soaking
Taking out the membrane completely subjected to phase separation in the step 3, placing the membrane in deionized water for soaking for 48 hours, removing residual organic solvent in the membrane, taking out the membrane and drying the membrane in the air to obtain a PVC/EVOH binary blending flat ultrafiltration membrane;
FIG. 5 is a cross-sectional structural view of the PVC/EVOH binary-blended flat ultrafiltration membrane prepared in the present embodiment;
FIG. 6 is a surface structure diagram of the PVC/EVOH binary blended flat ultrafiltration membrane prepared in this example.
Example 4
A preparation method of a PVC/EVOH binary blending flat ultrafiltration membrane comprises the following steps:
step 1.1
Weighing the following raw materials in percentage by mass and mixing: 17% PVC,1% EVOH,48.9% ethylene glycol monoethyl ether acetate, 6% PEG800, 27.1% dimethyl sulfoxide;
step 1.2
Heating the mixture obtained in the step 1.1 to 100 ℃, stirring to form a uniform and transparent solution, and obtaining a membrane casting solution after the solution is defoamed completely;
At room temperature, scraping a membrane with the thickness of 200 mu m on the surface of polyethylene glycol terephthalate non-woven fabric with the thickness of 100 mu m at the speed of 1m/s by using the membrane casting solution, and staying in air for 60s to prepare a flat membrane;
Putting the flat membrane into a 25 ℃ water coagulating bath for curing to form a membrane;
step 4 soaking
Taking out the membrane completely subjected to phase separation in the step 3, placing the membrane in deionized water for soaking for 48 hours, removing residual organic solvent in the membrane, taking out the membrane and drying the membrane in the air to obtain a PVC/EVOH binary blending flat ultrafiltration membrane;
FIG. 7 is a cross-sectional structural view of the PVC/EVOH binary blended flat ultrafiltration membrane prepared in the present example;
FIG. 8 is a surface structure diagram of the PVC/EVOH binary blended flat ultrafiltration membrane prepared in this example.
Example 5
A preparation method of a PVC/EVOH binary blending flat ultrafiltration membrane comprises the following steps:
step 1.1
Weighing the following raw materials in percentage by mass and mixing: 17% PVC,1% EVOH,21.7% γ -butyrolactone, 6% PEG1000, 54.3% dimethyl sulfoxide;
step 1.2
Heating the mixture obtained in the step 1.1 to 90 ℃, stirring to form a uniform transparent solution, and obtaining a membrane casting solution after the solution is defoamed completely;
Scraping a membrane with the thickness of 250 mu m on the surface of polyethylene terephthalate non-woven fabric with the thickness of 100 mu m at the speed of 1m/s by using the membrane casting solution at room temperature, and staying in the air for 30s to prepare a flat membrane;
Putting the flat membrane into a 25 ℃ water coagulating bath for curing to form a membrane;
step 4 soaking
Taking out the membrane completely subjected to phase separation in the step 3, placing the membrane in deionized water for soaking for 48 hours, removing residual organic solvent in the membrane, taking out the membrane and drying the membrane in the air to obtain a PVC/EVOH binary blending flat ultrafiltration membrane;
FIG. 9 is a cross-sectional structural view of the PVC/EVOH binary-blended flat ultrafiltration membrane prepared in the present embodiment;
FIG. 10 is a surface structure diagram of the PVC/EVOH binary blended flat ultrafiltration membrane prepared in the present example;
example 6
A preparation method of a PVC/EVOH binary blending flat ultrafiltration membrane comprises the following steps:
step 1.1
Weighing the following raw materials in percentage by mass and mixing: 19% PVC,1% EVOH,47.6% γ -butyrolactone, 6% PEG1500, 26.4% dimethyl sulfoxide;
step 1.2
Heating the mixture obtained in the step 1.1 to 100 ℃, stirring to form a uniform and transparent solution, and obtaining a membrane casting solution after the solution is defoamed completely;
At room temperature, scraping a membrane with the thickness of 300 microns on the surface of polyethylene glycol terephthalate non-woven fabric with the thickness of 100 microns by using the membrane casting solution at the speed of 1m/s, and staying in air for 30 seconds to prepare a flat membrane;
Putting the flat membrane into a 25 ℃ water coagulating bath for curing to form a membrane;
step 4 soaking
Taking out the membrane completely subjected to phase separation in the step 3, placing the membrane in deionized water for soaking for 48 hours, removing residual organic solvent in the membrane, taking out the membrane and drying the membrane in the air to obtain a PVC/EVOH binary blending flat ultrafiltration membrane;
FIG. 11 is a cross-sectional structural view of the PVC/EVOH binary-blended flat ultrafiltration membrane prepared in this example;
FIG. 12 is a surface structure diagram of the PVC/EVOH binary blended flat ultrafiltration membrane prepared in this example.
Comparative example 1
A preparation method of a PVC/EVOH binary blending flat ultrafiltration membrane comprises the following steps:
step 1.1
Weighing the following raw materials in percentage by mass and mixing: 19% PVC,1% EVOH,51.5% γ -butyrolactone, 28.5% dimethyl sulfoxide;
step 1.2
Heating the mixture obtained in the step 1.1 to 95 ℃, stirring to form a uniform transparent solution, and obtaining a membrane casting solution after the defoaming is completed;
At room temperature, scraping a membrane with the thickness of 300 microns on the surface of polyethylene glycol terephthalate non-woven fabric with the thickness of 100 microns by using the membrane casting solution at the speed of 1m/s, and staying in air for 30 seconds to prepare a flat membrane;
Putting the flat membrane into a 25 ℃ water coagulating bath for curing to form a membrane;
step 4 soaking
Taking out the membrane completely subjected to phase separation in the step 3, placing the membrane in deionized water for soaking for 48 hours, removing residual organic solvent in the membrane, taking out the membrane and drying the membrane in the air to obtain a PVC/EVOH binary blending flat ultrafiltration membrane;
FIG. 13 is a cross-sectional structural view of a PVC/EVOH binary-blended flat ultrafiltration membrane prepared in this comparative example;
FIG. 14 is a surface structure diagram of a PVC/EVOH binary blended flat ultrafiltration membrane prepared in this comparative example.
Comparative example 2
A preparation method of a PVC/EVOH binary blending flat ultrafiltration membrane comprises the following steps:
step 1.1
Weighing the following raw materials in percentage by mass, and mixing: 19% PVC,1% EVOH,80% N, N-dimethylacetamide;
step 1.2
Heating the mixture obtained in the step 1.1 to 95 ℃, stirring to form a uniform transparent solution, and obtaining a membrane casting solution after the solution is defoamed completely;
At room temperature, scraping a membrane with the thickness of 300 mu m on the surface of polyethylene glycol terephthalate non-woven fabric with the thickness of 100 mu m at the speed of 1m/s by using the membrane casting solution, and staying in air for 60s to prepare a flat membrane;
Putting the flat membrane into a 25 ℃ water coagulating bath for curing to form a membrane;
step 4 soaking
Taking out the membrane completely subjected to phase separation in the step 3, placing the membrane in deionized water for soaking for 48 hours, removing residual organic solvent in the membrane, taking out the membrane and drying the membrane in the air to obtain a PVC/EVOH binary blending flat ultrafiltration membrane;
FIG. 15 is a cross-sectional structural view of a PVC/EVOH binary-blended flat ultrafiltration membrane prepared in this comparative example;
FIG. 16 is a surface structure view of a PVC/EVOH binary blended flat ultrafiltration membrane prepared in this comparative example;
comparing fig. 1, 3, 5, 7, 9, 11 and 13, it can be seen that: the section of the membrane prepared by the scheme of the invention is in a sponge shape, and the section of the membrane without diluent or non-diluent is in a finger shape; when the content of the non-diluent is certain and the content of the diluent is less, enough air retention time is needed to prepare the membrane with the cross section in a sponge hole; when the content of the diluent is high, the cross section of the membrane is in a sponge hole shape after a short air retention time. In addition, when no non-diluent is added, although the content of the diluent is higher than that of the solvent, the sponge pore structure obtained in the same air residence time is incomplete, and small elliptical pores are remained;
comparing fig. 2, 4, 6, 8, 10, 12 and 14, it can be seen that: the surface layer of the membrane prepared by the scheme of the invention is rich in micropores, and the surface of the membrane without diluent or non-diluent is sealed, so that pores are difficult to see; in addition, when no non-diluent is added, the porosity of the membrane surface decreases for the same diluent to solvent ratio.
Experimental example 1
1. And (3) testing the water flux of the membrane:
cutting a circular membrane with the effective diameter of 5.5cm, cleaning and placing in a flux test device; after prepressing at 0.15MPa for 30min, the pure water flux was measured at 0.10MPa, the volume of the filtrate obtained by filtration over a certain period of time was recorded, and the measurement was calculated by substituting the following equation:
j = V/(S · t); in the formula: j-pure water flux, L/(m) 2 H); v is the pure water permeate volume, L; s-effective area of the film, m 2 (ii) a t-time taken to collect the pure water permeate, h;
2. testing of membrane rejection:
preparing a bovine serum albumin solution with the mass concentration of 1g/L, testing the absorbance of the original bovine serum albumin solution and the filtrate at 280nm under the pressure of 0.10MPa at the same time interval, and calculating the retention rate according to the relationship between the absorbance and the concentration and the following formula:
R＝(C 0 -C 1 )/C 0 x is 100%; in the formula: r-retention,%; c 0 -bovine serum albumin concentration in stock solution, mol/L; c 1 -bovine serum albumin concentration in permeate, mol/L;
3. and (3) testing mechanical properties:
testing the mechanical property of the membrane by adopting a universal testing machine according to GB/T1040.3-2006, wherein the stretching speed is 10mm/min, cutting the membrane into sample strips with smooth edges and no gaps according to requirements, wherein the sample strips are 15mm in width and 200mm in length;
4. the performance of the PVC/EVOH binary blended flat ultrafiltration membranes of examples 1-6 and comparative examples 1-2 is shown in Table 1:
TABLE 1
Claims (7)
1. A preparation method of a PVC/EVOH binary blending flat ultrafiltration membrane with a sponge pore structure is characterized by comprising the following steps:
1) Preparing a casting solution: weighing polyvinyl chloride, ethylene-vinyl alcohol copolymer, diluent, non-diluent and solvent according to the formula of the casting solution, mixing, heating to 20-100 ℃, stirring for 1-12h, and standing and defoaming completely to obtain the casting solution;
2) Scraping: at room temperature, the casting solution is scraped and coated on non-woven fabric at the speed of 0.1-5 m/s to prepare a membrane, and the membrane stays in the air for 10-240s;
3) And (3) curing: immersing the membrane into a coagulating bath to be solidified into a membrane;
4) Soaking: soaking the cured film in deionized water for more than 48h for later use;
the formula amount of the casting solution is as follows by mass fraction: 10-25% of polyvinyl chloride, 8-50% of diluent, 2-10% of non-diluent, 25-65% of solvent and 1-5% of ethylene-vinyl alcohol copolymer; the diluent is water-soluble ester with poor solubility with the polymer and high boiling point;
the diluent is one of gamma-butyrolactone, ethylene carbonate, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, propylene glycol monoethyl ether acetate and dipropylene glycol monoethyl ether acetate;
the non-diluent is water-soluble polyethylene glycol;
the mass ratio of the solvent to the diluent in the casting solution is 1:2-3:1, and the mass ratio of the diluent to the non-diluent in the casting solution is 3:1-10.
2. The preparation method of the PVC/EVOH binary blending flat ultrafiltration membrane with the sponge pore structure as claimed in claim 1, wherein the non-woven fabric is any one of polyethylene terephthalate or polyamide non-woven fabric, and the thickness of the non-woven fabric is 50-150 μm.
3. The preparation method of the PVC/EVOH binary blending flat ultrafiltration membrane with the sponge pore structure as claimed in claim 1, wherein the molecular weight of the polyethylene glycol is one of 200g/mol, 400g/mol, 600g/mol, 800g/mol, 1000g/mol, 1500g/mol, 2000g/mol, 4000g/mol, 6000g/mol, 8000g/mol, 10000g/mol and 20000 g/mol.
4. The method for preparing the PVC/EVOH binary blending flat ultrafiltration membrane with the sponge pore structure as claimed in claim 1, wherein the solvent is one of N, N-dimethylformamide, N-dimethylacetamide, N-methylpyrrolidone, triethyl phosphate, trimethyl phosphate and dimethyl sulfoxide.
5. The preparation method of the PVC/EVOH binary blended flat ultrafiltration membrane with the sponge pore structure according to claim 1, wherein the thickness of the membrane sheet in the step 2) is 20-300 μm.
6. The preparation method of the PVC/EVOH binary blended flat ultrafiltration membrane with the sponge pore structure as claimed in claim 1, wherein the coagulating bath in step 3) is water.
7. The preparation method of the PVC/EVOH binary blending flat ultrafiltration membrane with the sponge pore structure as claimed in any one of claims 1-6, which is characterized by comprising the following steps:
1) Preparing a casting solution: weighing polyvinyl chloride, ethylene-vinyl alcohol copolymer, diluent, non-diluent and solvent according to the formula of the casting solution, mixing, heating to 90-100 ℃, stirring for 1-12h, and standing for defoaming completely to obtain the casting solution;
2) Scraping: at room temperature, the casting solution is coated on non-woven fabric at the speed of 0.1-5 m/s to prepare a membrane and the membrane stays in the air for 30-60s;
3) And (3) curing: soaking the membrane into a water coagulation bath to be solidified into a membrane;
4) Soaking: soaking the cured film in deionized water for 48h for later use;
the formula amount of the casting solution is as follows by mass fraction: 14-20% of polyvinyl chloride, 20-45% of diluent, 2-10% of non-diluent, 26-55% of solvent and 1-5% of ethylene-vinyl alcohol copolymer; the mass ratio of the solvent to the diluent in the casting solution is 1:2-3:1, and the mass ratio of the diluent to the non-diluent in the casting solution is 3:1-6:1.
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Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102743980A (en) * | 2012-08-01 | 2012-10-24 | 柳州森淼环保技术开发有限公司 | Manufacture method of polyvinyl chloride panel ultrafiltration membrane |
| CN103071394A (en) * | 2013-02-08 | 2013-05-01 | 上海中科高等研究院 | Preparation method of high-flux hydrophilic microporous filtering film and application thereof |
| CN106606932A (en) * | 2015-10-21 | 2017-05-03 | 华东理工大学 | Preparation method of low-cost control polyvinyl chloride (PVC) ultrafiltration membrane pore structure |
| CN106823867A (en) * | 2017-03-06 | 2017-06-13 | 北京理工大学 | Using the method for polyalcohols/ester blend hydrophilic modification hydrophobic type polymeric membrane for separation |
| JP2017127864A (en) * | 2017-01-31 | 2017-07-27 | ユニチカ株式会社 | Polyamide ultrafilter membrane having organic solvent tolerance and manufacturing method for the same |
| CN107051231A (en) * | 2017-06-09 | 2017-08-18 | 天津工业大学 | The preparation method of polyvinyl chloride homogeneous perforated membrane |
| CN113318611A (en) * | 2021-05-31 | 2021-08-31 | 天津工业大学 | Hollow fiber ultrafiltration membrane with lasting high pollution resistance and preparation method thereof |
-
2021
- 2021-12-08 CN CN202111496503.9A patent/CN114259877B/en active Active
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102743980A (en) * | 2012-08-01 | 2012-10-24 | 柳州森淼环保技术开发有限公司 | Manufacture method of polyvinyl chloride panel ultrafiltration membrane |
| CN103071394A (en) * | 2013-02-08 | 2013-05-01 | 上海中科高等研究院 | Preparation method of high-flux hydrophilic microporous filtering film and application thereof |
| CN106606932A (en) * | 2015-10-21 | 2017-05-03 | 华东理工大学 | Preparation method of low-cost control polyvinyl chloride (PVC) ultrafiltration membrane pore structure |
| JP2017127864A (en) * | 2017-01-31 | 2017-07-27 | ユニチカ株式会社 | Polyamide ultrafilter membrane having organic solvent tolerance and manufacturing method for the same |
| CN106823867A (en) * | 2017-03-06 | 2017-06-13 | 北京理工大学 | Using the method for polyalcohols/ester blend hydrophilic modification hydrophobic type polymeric membrane for separation |
| CN107051231A (en) * | 2017-06-09 | 2017-08-18 | 天津工业大学 | The preparation method of polyvinyl chloride homogeneous perforated membrane |
| CN113318611A (en) * | 2021-05-31 | 2021-08-31 | 天津工业大学 | Hollow fiber ultrafiltration membrane with lasting high pollution resistance and preparation method thereof |
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