TWI661862B - Modified polyether 碸 microporous membrane and preparation method thereof - Google Patents

Abstract

A method for preparing a modified polyether 碸 microporous membrane comprises the following steps: (1) providing a casting solution obtained by polymerization of a precursor liquid, the precursor liquid comprising polyether hydrazine And vinyl caprolactam and a radical initiator; (2) distributing the casting solution on a substrate; and (3) phase-transforming the casting solution on the substrate to form the microporous membrane . The porogen is not required to be added to the casting solution of the preparation method of the present invention, and the modified polyether 碸 microporous membrane prepared in the subsequent manner is also hydrophilic.

Description

Modified polyether 碸 microporous membrane and preparation method thereof

The invention relates to a preparation method of a microporous membrane and a microporous membrane, in particular to a preparation method of a modified polyethersulfone (PES) microporous membrane and a modified polyether 碸 microporous membrane .

Since the polyether 碸 microporous membrane is a hydrophobic microporous membrane, it is limited in filtering aqueous media. Therefore, many studies on how to improve the hydrophilicity of polyether 碸 microporous membranes have been proposed.

For example, US Pat. No. 5,431,217 discloses a preparation method for preparing a hydrophilic polyether ruthenium filter membrane by adding a pore-former or a pore-forming component to prepare a casting solution and casting the casting solution. The polyether oxime membrane is obtained by phase inversion of the membrane fluid. It has been disclosed herein that a hydrophilic property is obtained by adding a low molecular weight or high molecular weight pore former, for example, adding polyethylene glycol [poly(ethylene glycol), PEG] or polyvinylpyrrolidone (PVP) as a pore former. And since both PEG and PVP are hydrophilic polymers, during the film formation process, the membrane is pore-forming through the film-forming mechanism of mass transfer or heat transfer, and most of the pore former is released into the precipitation bath. A small part will be entangled with the PES to retain the polymer and remain in the filter membrane, thus making the filter membrane hydrophilic, and most of the pore former will be released into the precipitation bath during the film formation process. The wastewater is not easy to handle, and excessive use can cause environmental pollution. In addition, in order to obtain an open-pored microporous film structure, it is often brought to an unstable state by adding a non-solvent (one of the pore formers) to the casting solution. The filter membrane is prepared, but if the addition of the non-solvent is excessive, the casting solution is phase-separated, and therefore, it takes a lot of time to prepare the casting solution.

Therefore, how to find a hydrophilic polyether 碸 microporous membrane without the addition of a pore former in the casting solution and subsequent production of an interpenetrating film structure has become a research goal.

Accordingly, a first object of the present invention is to provide a process for preparing a modified polyether oxime microporous membrane. The preparation method of the invention does not need to add a pore former to the casting solution, and the modified polyether 碸 microporous membrane prepared in the subsequent manner has an interpenetrating film structure and also has hydrophilicity.

Therefore, the preparation method of the modified polyether 碸 microporous membrane of the present invention comprises the following steps: (1) providing a casting solution, which is prepared by polymerization of a precursor liquid, and the precursor liquid comprises Polyether oxime, vinyl caprolactam (VCL) and a radical initiator, the precursor liquid does not contain a pore former; (2) distributing the casting solution on a substrate; 3) Phase-transforming the casting solution on the substrate to form the microporous filter.

Accordingly, a second object of the present invention is to provide a modified polyether oxime microporous membrane having hydrophilicity.

Therefore, the modified polyether 碸 microporous membrane of the present invention is formed by a casting solution which is obtained by polymerization of a precursor liquid, and the precursor liquid comprises polyether oxime and vinyl hexanone. Indoleamine and a free radical initiator, the precursor fluid does not contain a pore former.

The effect of the present invention is that the precursor liquid for preparing the casting liquid in the preparation method of the present invention contains vinyl caprolactam in addition to the polyether oxime, and therefore, the present invention is compared with the prior preparation method. The preparation method does not need to add a pore former to the casting solution, and the modified polyether 碸 microporous membrane prepared in the subsequent manner has an interpenetrating film structure and also has hydrophilicity.

The contents of the present invention will be described in detail below:

[ Method for preparing modified polyether 碸 microporous membrane ]

Following the steps (1) The precursor fluid further explains:

The pore former is an agent added to the casting solution for forming pores in the subsequently formed film. Preferably, the pore former is selected from the group consisting of non-solvents, metal salts, metal oxides, organometallics, polymers or combinations of the foregoing. The non-solvent is, for example but not limited to, water, glycerin, methanol, ethanol, isopropanol, n-propanol, diethylene glycol or the foregoing. The metal oxide is, for example but not limited to, titanium dioxide; the polymer is, for example but not limited to, polyvinylpyrrolidone (PVP), polyethylene glycol (PEG), polyvinyl butyrals (PVB). ), heavy petroleum fractions or a combination of the foregoing.

The free radical initiator is, for example but not limited to, azobisisobutyronitrile (IABN).

Preferably, the precursor liquid further comprises a solvent selected from the group consisting of epsilon-caprolactam, epsilon-caprolactone, gamma-butyrolactone (gamma-butyrolactone) ) or a combination of the foregoing. More preferably, the solvent consists of epsilon-caprolactam and gamma-butyrolactone.

Preferably, the precursor fluid is composed of polyether oxime, vinyl caprolactam, a free radical initiator and a solvent. This solvent is the same as the solvent described in the above paragraph 0015. More preferably, the preferred weight range and better weight of the ingredients added to the precursor are summarized in Table 1 below. Table 1  Component weight range (parts by weight) better weight range (parts by weight) Polyether 碸 10~20 10~15 Vinyl caprolactam 7~25 13~23 Solvent 40~100 60~80 Free radical initiator 0.01 ~0.3 0.05~0.15

More preferably, when the solvent is composed of epsilon-caprolactam and gamma-butyrolactone, the weight of the epsilon-caprolactam and the gamma-butyrolactone is 20-50 weight respectively. Share.

Preferably, the precursor liquid further comprises a monomer capable of forming a copolymer after being polymerized with the vinyl caprolactam.

Following the steps (1) The casting solution further illustrates:

The casting solution is prepared by polymerization of a precursor liquid.

Preferably, the precursor liquid is subjected to polymerization at 60 to 100 °C. More preferably, the polymerization is carried out at 70 to 90 °C.

Preferably, the precursor liquid is subjected to a polymerization reaction for more than 8 hours. More preferably, the polymerization time is from 14 to 18 hours.

Preferably, the casting solution comprises a polyether oxime and a hydrophilic polymer having a vinyl caprolactam unit, and the casting solution does not contain a pore former.

More preferably, the casting solution further contains a solvent. Still more preferably, the casting solution is composed of a polyether oxime, a hydrophilic polymer having a vinyl caprolactam unit, and a solvent. This solvent is the same as the solvent described in the above paragraph 0015.

The hydrophilic polymer having a vinyl caprolactam unit may be poly(vinyl caprolactam), PVCL or a copolymer thereof. More preferably, the hydrophilic polymer is polyvinyl caprolactam (PVCL).

More preferably, the hydrophilic polymer has a low critical solution temperature (LCST), and the low critical solution temperature ranges from 25 to 60 °C. Still more preferably, the low critical solution temperature ranges from 30 to 50 °C. It should be noted that the temperature of the low critical solution is obtained by dissolving the hydrophilic polymer in water at a concentration ratio of 1 wt%, and then testing with a spectrophotometer.

Preferably, the casting solution has a viscosity in the range of 1.5 to 7 Pa·s at 60 ° C.

Following the steps (2) Further explanation:

Preferably, the substrate does not have any holes.

Preferably, the material of the substrate can be a material suitable for use with a casting solution. More preferably, the material of the substrate is glass or a polymer. The polymer is, for example but not limited to, polyethylene terephthalate (PET).

Following the steps (3) Further explanation:

The method of phase-transforming the casting solution can be any one of the methods for forming the film into a film. The method of phase transformation is, for example but not limited to, utilizing a non-solvent induced phase separation or a vapor induced phase separation. Preferably, the casting solution is subjected to phase transformation by a non-solvent induced phase separation method in combination with a vapor induced phase separation method.

Preferably, the step (3) comprises the following steps: (3-1) exposing the casting solution on the substrate to an environment having a temperature range of 35 to 55 ° C and a relative humidity range of 50 to 100%; (3-2) The casting solution treated in the step (3-1) is immersed in water to form the modified polyether 碸 microporous membrane.

More preferably, in the step (3-1), the layer of the casting solution is exposed to an environment having a relative humidity ranging from 60 to 100%.

More preferably, in the step (3-1), the exposure time of the casting solution on the substrate ranges from 10 to 60 seconds.

More preferably, when the step (3) comprises the aforementioned steps (3-1) and (3-2) and the casting solution contains a hydrophilic polymer having a vinyl caprolactam unit, and the hydrophilic polymer In the case of a low critical solution temperature, in the step (3-1), the casting solution is exposed to an environment having a temperature higher than the temperature of the low critical solution.

More preferably, the step (3-2) is immersed in water at 20 to 30 ° C to form a film, and the film is washed with water at 50 to 70 ° C to obtain the modified polyether 碸 microporous membrane. .

[ Modified polyether 碸 microporous membrane ]

Preferably, the modified polyether 碸 microporous membrane of the present invention comprises an air side, a roll side opposite to the air side, a selective layer between the air side and the roll side, and a side located on the air side. And a protective layer between the selected layers, the selected layer having a thickness of 5 to 50 μm and having a minimum aperture. In particular, the protective layer is to prevent the selected layer from being damaged, and the thickness thereof can be adjusted according to the process. More preferably, the modified polyether 碸 microporous membrane of the present invention further comprises a support layer between the selective layer and the roll side, the support layer having a sponge-like uniform pore structure, and the thickness thereof occupies the micro The overall thickness of the pore filter is 50~75%.

Preferably, the modified polyether 碸 microporous membrane of the present invention has a mean flow pore diameter ranging from 0.05 to 1 μm.

Preferably, the modified polyether 碸 microporous membrane of the present invention has a thickness of 100 to 130 μm.

Preferably, the modified polyether 碸 microporous membrane of the present invention has a porosity ranging from 75 to 85 vol.%.

Preferably, the transmembrane flow (TMM) of the modified polyether 碸 microporous membrane of the present invention ranges from 26,000 to 63000 L/(m ² ·hr·bar).

The present invention will be further illustrated by the following examples, but it should be understood that the examples are merely illustrative and not to be construed as limiting.

< Example 1>

Preparation of modified polyether 碸 microporous membrane step (1) : mixing 12 parts by weight of polyether oxime (model: 5900P; manufacturer: Sumitomo Chemical Co., Ltd.), 18 parts by weight of vinyl caprolactam, 43.9 weight After a portion of gamma-butyrolactone, 26 parts by weight of epsilon-caprolactone, and 0.1 part by weight of azobisisobutyronitrile (AIBN), a precursor liquid was obtained. Next, the precursor liquid was first subjected to polymerization at 80 ° C for 16 hours, and then cooled to 60 ° C for 1 hour to obtain a casting solution. It should be noted that the viscosity of the casting solution at 60 ° C is 1.671 Pa·s, and the casting solution contains polyethylene caprolactam (hydrophilic polymer) having a low critical solution temperature range of 36 ° C. . Step (2) : distributing the casting solution on a substrate having no holes. Step (3-1) : The layer of the casting solution on the substrate was exposed to an environment having a temperature of 40 ° C and a relative humidity of 70% for 20 seconds. Step (3-2) : completely immersing the substrate containing the casting solution after the step (3-1) in water at 25 ° C to form a film which can be detached from the substrate, and then using hot water at 60 ° C The film was washed and dried at 60 ° C to finally obtain a modified polyether 碸 microporous membrane of Example 1.

< Example 2>

preparation Modified polyether 碸 microporous membrane

The preparation method of the modified polyether 碸 microporous membrane of Example 2 is similar to that of Example 1, except that the step (3-1) of Example 2 is to expose the layer of the casting solution on the substrate. The temperature was 40 ° C and the relative humidity was 100% for 20 seconds.

<Embodiment 2 of Example 1 to change Polyether sulfone microporous membrane structure analysis> A. mean flow pore size (mean flow pore diameter): in a pore size analyzer (Manufacturer: PMI) Analysis of Examples 1 and 2 to change the quality of Poly The average flow pore size of the ether oxime microporous membrane was obtained in Table 2 below. B. film thickness (thickness): a thickness gauge (thickness gauge) measuring the thickness change Examples 1-2 Polyether sulfone microporous membrane of the embodiment, in summary of the results obtained in Table 2. C. porosity (porosity): according to the following Formula I and Formula II to calculate the porosity of Example 1 and 2 to change the mass of the polyether sulfone porous membrane (vol%.), In the summary of the results obtained in Table 2. [Formula I] Porosity (vol.%) = [(Vm - Vp) / Vm] × 100% [Formula II] Vp = Wm / ρ _p where Vm: total volume of the film (cm ³ , bulk volume), Multiplied by the film area multiplied by the film thickness; Vp: polymer volume (cm ³ ) in the film; Wm: film weight (g); ρ _p : polymer density (g/cm ³ ), PES density 1.37 g / Cm ³ . D. Transmembrane flow (TMF) : The modified polyether 碸 microporous membrane of Examples 1 to 2 was first cut to a diameter of 47 mm, and clamped to a water supply under pressure. A disk-shaped film sample having a measured area of 11.34 cm ² was obtained in the container. Next, deionized water was passed through the film sample from the side where the film sample was placed, under a pressure of 0.4 bar. The volume of deionized water (1 L) passing through the membrane sample was determined in a weighted or volumetric manner during the measurement period. The transmembrane flow rate of the modified polyether 碸 microporous membranes of Examples 1 to 2 [TMF, L/(m ² ·hr·bar)] was calculated according to the following formula III, and the final results were summarized in Table 2 below. . [Formula III] TMF [L/(m ² ·hr·bar)]=V/( t·A·∆P) where V is the volume of water passing through the film sample (L); t: measuring time ( Hr); A: area of the film sample (m ² ); ∆P: pressure during measurement (bar). Table 2 Example 1 Example 2 Average flow pore size (μm) 0.21 0.50 Film thickness (μm) About 105 About 105 Porosity (vol.%) 78 81 Transmembrane flow rate [L/(m2·hr·bar)] 31000 58000 E. Scanning electron microscope (SEM) : The modified polyether 碸 microporous membranes of Examples 1 and 2 were photographed by a scanning electron microscope, and the results are shown in Figs. 1 to 2 are cross-sectional SEM photographs of the modified polyether 碸 microporous membrane of Example 1 (Fig. 1 is magnified 500 times; Fig. 2 is magnified 3000 times). 1 and 2, the modified polyether 碸 microporous membrane obtained by the preparation method of the first embodiment comprises an air side 1, a roll side 2 opposite to the air side 1, and a side located on the air side. a selection layer between the roller side 2, a protective layer between the air side 1 and the selection layer, and a support layer between the selection layer and the roller side 2. The thickness of the selected layer is 10 μm and the pores in the selected layer will have the smallest pore size compared to the other portions of the filter. The filter film is located between the selected layer and the air side 1 and the hole size is gradually increased from the selected layer toward the air side 1. The support layer has a sponge-like and non-fingered uniform pore structure and a thickness of 75% of the thickness of the microporous membrane. Figure 3 is a cross-sectional SEM photograph (magnification 500 times) of the modified polyether 碸 microporous membrane of Example 2. As can be seen from FIG. 3, the modified polyether 碸 microporous membrane prepared by the preparation method of Example 2 includes an air side 1, a roll side 2 opposite to the air side 1, and a side 1 on the air side. A selective layer between the roller sides 2 and a protective layer between the air side 1 and the selected layer. The thickness of the selected layer is 50 μm and the pores in the selected layer will have the smallest pore size compared to the other portions of the filter. The filter film is located between the selected layer and the air side 1 and the hole size is gradually increased from the selected layer toward the air side 1. The selected layer occupies 50% of the thickness of the microporous filter. In addition, FIG. 4 is a SEM photograph (magnification 3000 times) of the roll side 2 of the modified polyether 碸 microporous membrane of Example 1, and FIG. 5 is the air side of the modified polyether 碸 microporous membrane of Example 1. The SEM photograph of 1 (magnification 3000 times), as shown in Fig. 4 and Fig. 5, the modified polyether 碸 microporous membrane obtained by the preparation method of the present invention has a structure having an open pore. It is particularly worth mentioning that it can also be observed from Figures 1, 3 to 5 that the modified polyether 碸 microporous membrane of the present invention will have an interpenetrating film structure.

In summary, since the precursor liquid used for preparing the casting liquid in the preparation method of the present invention contains vinyl caprolactam in addition to the polyether oxime, the present invention is prepared in comparison with the existing preparation method. The method does not need to add a pore former in the casting solution, and the modified polyether 碸 microporous membrane prepared in the subsequent manner has an interpenetrating film structure and also has hydrophilicity, so the object of the invention can be achieved. .

However, the above is only the embodiment of the present invention, and the scope of the invention is not limited thereto, and all the simple equivalent changes and modifications according to the scope of the patent application and the patent specification of the present invention are still Within the scope of the invention patent.

1‧‧‧air side

2‧‧‧ Roll side

Other features and effects of the present invention will be apparent from the following description of the drawings, wherein: Figure 1 is a SEM photograph illustrating the cross section of the modified polyether 碸 microporous membrane of Example 1. Figure 2 is a SEM photograph showing the selected layer cross section of the modified polyether 碸 microporous membrane of Example 1 (magnification 3000 times); Figure 3 is a SEM photograph illustrating the modification of Example 2. Cross section of the polyether 碸 microporous membrane (magnification 500 times); Figure 4 is a SEM photograph illustrating the roll side of the modified polyether 碸 microporous membrane of Example 1 (magnification 3000 times); and Figure 5 It is an SEM photograph showing the air side (magnification 3000 times) in the modified polyether 碸 microporous membrane of Example 1.

Claims (10)

A method for preparing a modified polyether 碸 microporous membrane comprises the following steps: (1) providing a casting solution obtained by polymerization of a precursor liquid, the precursor liquid comprising polyether hydrazine a vinyl caprolactam and a radical initiator, the precursor fluid and the casting solution do not comprise a pore former; (2) distributing the casting solution on a substrate; and (3) making the substrate The casting solution undergoes a phase transition to form the microporous filter. The method for preparing a modified polyether 碸 microporous membrane according to claim 1, wherein in the step (1), the porogen is selected from the group consisting of a non-solvent, a metal salt, a metal oxide, and an organic metal. A compound, a polymer or a combination of the foregoing, which is selected from the group consisting of water, glycerin, methanol, ethanol, isopropanol, n-propanol, diethylene glycol or a combination of the foregoing. The method for preparing a modified polyether 碸 microporous membrane according to claim 1, wherein the precursor further comprises a solvent selected from the group consisting of epsilon-caprolactam, epsilon-caprolactone, gamma- Butyrolactone or a combination of the foregoing. The method for preparing a modified polyether 碸 microporous membrane according to claim 1, wherein the step (3) comprises the following steps: (3-1) exposing the casting solution on the substrate to a temperature range. The environment is 35 to 55 ° C and the relative humidity is 50 to 100%; and (3-2) the casting solution after the step (3-1) is immersed in water to form the microporous membrane. The method for producing a modified polyether 碸 microporous membrane according to claim 1, wherein the casting solution comprises a hydrophilic polymerization having a vinyl caprolactam unit And the hydrophilic polymer has a low critical solution temperature ranging from 25 to 60 °C. A modified polyether 碸 microporous membrane formed by a casting solution prepared by polymerization of a precursor liquid comprising polyether oxime and vinyl caprolactam And a radical initiator, the precursor fluid and the casting solution do not contain a pore former. The modified polyether 碸 microporous membrane according to claim 6, wherein the precursor liquid further comprises a solvent selected from the group consisting of epsilon-caprolactam, epsilon-caprolactone, gamma-butyrolactone. Or a combination of the foregoing. The modified polyether 碸 microporous membrane according to claim 6, comprising an air side, a roller side opposite to the air side, a selective layer between the air side and the roller side, and a air located in the air A protective layer between the side and the selected layer, the selected layer having a thickness of 5 to 50 μm and having a minimum aperture. The modified polyether 碸 microporous membrane according to claim 8, further comprising a support layer between the selective layer and the roll side, the support layer having a sponge-like uniform pore structure, and the thickness thereof The overall thickness of the microporous membrane is 50~75%. The modified polyether 碸 microporous membrane according to claim 6, wherein the modified polyether 碸 microporous membrane has an average flow pore size ranging from 0.05 to 1 μm.