KR100823629B1 - Polyvinlylidenefluoride membrane surface modifying device - Google Patents

Abstract

An apparatus for surface modification of a polyvinlylidene fluoride membrane is provided to improve hydrophilicity on the surface of the membrane and reduce the impregnating time by coating an impregnating solution containing an acrylic monomer and a photo initiator with a surface of the membrane and filling the impregnating solution into pores of the membrane, thereby graft-polymerizing a hydrophilic functional group on the surface as well as in the pores of the membrane through light irradiation. An apparatus for surface modification of a polyvinlylidene fluoride membrane comprises: a first impregnating equipment(200) impregnating a porous polyvinlylidene fluoride membrane having a plurality of pores formed therein with an impregnating solution; a pore sucking equipment(300) for filling the impregnating solution into the pores of the porous polyvinlylidene fluoride membrane; and a reactor(600) for irradiating light onto the impregnated porous polyvinlylidene fluoride membrane to perform a surface modifying reaction. The impregnating solution is prepared by dissolving a photo initiator and a compound having a hydrophilic functional group into a volatile solvent. The compound is an acrylic monomer selected from the group consisting of acrylic acid, methacrylic acid, and glycidyl methacrylate. The photo initiator is 2,2-dimethoxy-2-phenylacetophenone. The apparatus further comprises an unwinder(100), a second impregnating equipment(400), a solvent volatilizing equipment(500), a reactant remover(700), a dryer(800), and a winder(900).

Description

Polyvinlylidenefluoride membrane surface modifying device

1 is a side view showing the configuration of a polyvinylidene fluoride membrane surface modification apparatus according to an embodiment of the present invention.

FIG. 2 is a front view of the pore suction device of the polyvinylidene fluoride membrane surface modification device of FIG. 1.

3 is an enlarged view of a pore suction unit of the pore suction device of FIG. 2.

4 is a cross-sectional view of the pore suction unit of FIG. 3.

* Brief description of the main parts of the drawing *

100: unwinding device, 200: primary impregnation device

300: pore suction device, 310: suction pipe

320: air inlet device, 330: porous suction pipe

400: secondary impregnation device, 500: solvent volatilization device

600: reaction device, 700: reactant removal device

800: drying device, 900: winding device

The present invention relates to polyvinylidene fluoride (PVDF) membrane surface modification apparatus, in particular polyvinylidene fluoride membrane surface modification apparatus for modifying the surface of polyvinylidene fluoride membrane to be hydrophilic .

Background Art Various graft polymerization methods for adding a hydrophilic functional group as a method of hydrophilizing a hydrophobic polymer surface have been known. Specifically, ozone [ Journal of Applied Polymer Science , 1999, 72 , 611], radiation [ Journal of Polymer Science , 1994, 51 , 1269, Radiation Physics and Chemistry , 1999, 54 , 637, and a method of forming a radical using plasma and ultraviolet light, and then introducing and grafting a hydrophilic monomer thereto is known.

However, the method has a low graft rate because only the surface layer of the polymer is modified, and because of the use of expensive equipment, the method has only limited application to small special films and separators [ Journal of Applied Polymer Science , 1998, 69 , 143]. ].

In addition, a method of branding between a hydrophilic polymer and a hydrophobic polymer is known. This method requires a high content of graft rate in the polymer of the main chain. As a method for obtaining a polymer having such a high graft rate, a method of grafting under supercritical carbon dioxide as disclosed in US Pat. No. 5,663,237, a method of grafting in a molten state of a polymer [ Journal of Applied Polymer Science , 1994, 53, 239]. In addition, US Pat. No. 5,079,032 discloses a solid-phase polymerization method in which a small amount of solvent is added to the surface to have flexibility and wettability, thereby maintaining the solid state during the reaction of the polymer.

However, the solid phase polymerization method is very limited because it attempts to introduce a hydrophilic hydrocarbon monomer into a hydrophobic polymer consisting mainly of hydrocarbons, and the reactor used is a Brabender type which is a mixer used commercially for solid-solid mixing. Since it is used as it is, there is a limit to the application.

As described above, the conventional technique is limited to the surface of the film type having no porosity, so that the water permeability is considerably low.

Therefore, when the conventional technique is applied to the porous film type, in the case of hydrophilization using plasma, the hydrophilization treatment into the internal pores is practically difficult in terms of practical technology and is difficult to commercialize due to the high cost.

In addition, the surface treatment method through UV light irradiation is now widely commercialized, but pretreatment mainly through the spray method and dipping method, which is a conventional pretreatment method, is inefficient as a hydrophilization treatment method for membranes for the purpose of improving water permeability. Therefore, it is not effective.

In addition, the conventional hydrophilization method does not adequately impregnate the membrane surfaces with low surface tension, but rather, the introduced hydrophilicity may lower the water permeability or cause pressure drop across the membrane. Can be.

Due to this phenomenon, various methods have recently been attempted to improve hydrophilic coatings. However, the permeability of the membrane coated with the proposed method up to this time shows a slight improvement or still low results, which are not satisfactory.

In order to solve the above technical problem, the present invention is to provide a membrane surface modification apparatus that can be hydrophilically modified by sufficiently impregnating the polyvinylidene fluoride membrane surface of the porous membrane to the inside of the pore.

 In order to solve the above technical problem, the polyvinylidene fluoride membrane surface modification apparatus according to an aspect of the present invention is the first impregnation impregnating the porous polyvinylidene fluoride membrane having a plurality of pores in the impregnation solution Device; A pore suction device filling the impregnation solution into the pores of the porous polyvinylidene fluoride membrane; And a reaction apparatus for performing a surface modification reaction by irradiating the impregnated porous polyvinylidene fluoride membrane with light.

The impregnation solution may be prepared by dissolving a compound having a hydrophilic functional group and a photoinitiator in a volatile solvent.

The compound may be an acrylic monomer selected from the group consisting of acrylic acid, methacrylic acid and glycidyl methacrylate.

The photoinitiator may be 2,2-dimethoxy-2-phenylacetophenone.

The volatile solvent may be an alcohol solvent selected from the group consisting of methyl alcohol, ethyl alcohol, propyl alcohol and isopropyl alcohol.

The pore suction device includes a suction tube disposed across a transport path of the polyvinylidene fluoride membrane; And an air inlet device provided at one side of the suction pipe to introduce air into the suction pipe.

The pore suction device may further include a porous suction pipe surrounding the suction pipe from the outside of the suction pipe.

The polyvinylidene fluoride membrane surface modification apparatus further includes a secondary impregnation apparatus for impregnating the porous polyvinylidene fluoride membrane, in which the impregnation solution is filled into the pores, into the impregnation solution in the pore suction device. can do.

The polyvinylidene fluoride membrane surface modification apparatus may further include a solvent volatilization apparatus including a heat source providing a temperature condition sufficient to volatilize the volatile solvent.

The heat source may be provided at the top and the bottom of the transport path of the polyvinylidene fluoride membrane.

The reactor may include a light source for irradiating light for decomposing the photoinitiator into radicals.

The light source may be provided above and below the transport path of the polyvinylidene fluoride membrane.

The polyvinylidene fluoride membrane surface modification apparatus may further include a reactant removal apparatus for washing the polyvinylidene fluoride membrane in which the reaction is completed in the reaction apparatus.

The polyvinylidene fluoride membrane surface modification apparatus may further include a drying apparatus for removing water used for washing in the reactant removing apparatus. The pore size may be 0.1 to 10㎛.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention.

Hereinafter, a polyvinylidene fluoride membrane surface modification apparatus according to an embodiment of the present invention will be described in detail with reference to FIG. 1.

As shown in FIG. 1, the polyvinylidene fluoride membrane surface modification apparatus according to an embodiment of the present invention includes an unwinding apparatus 100, a primary impregnation apparatus 200, a pore suction apparatus 300, and a secondary Impregnation device 400, solvent volatilization device 500, reaction device 600, reactant removal device 700, drying device 800, and winding device 900.

First, the unwinding apparatus 100 unwinds a polyvinylidene fluoride membrane introduced in a roll form to supply the polyvinylidene fluoride membrane to the primary impregnation apparatus 200. As the polyvinylidene fluoride membrane used in the present invention, a porous membrane having a plurality of pores having a size of 0.1 to 10 μm is used.

The primary impregnation apparatus 200 impregnates the polyvinylidene fluoride membrane unwound in the unwinding apparatus 100 into an impregnation solution containing a compound having a hydrophilic functional group and a photoinitiator. As the compound having a hydrophilic functional group, an acrylic monomer is preferably used. In the embodiment of the present invention, the impregnation solution is prepared by containing 10-50 g of acrylic monomer and 0.1-1.0 g of photoinitiator in 1 L of volatile solvent.

The acrylic monomer is any one selected from the group consisting of acrylic acid, methacrylic acid and glycidyl methacrylate, and 10 to 50 g per 1 L of solvent is used as a preferable content. At this time, when the content of the acrylic monomer is less than 10g / L, there is a problem that the amount of the appropriate monomer required for the reaction is small, the graft rate is low, the water permeability is lowered, and when the content of the acrylic monomer exceeds 50g / L, polyvinylidene fluoride The self-polymerization rate is higher than polymerization with the membrane, and the graft rate between the membrane surface and the monomer is low, which is undesirable.

As the photoinitiator, 2,2-dimethoxy-2-phenylacetophenone (2-dimethoxy-2-phenylaoctophenon) is preferably used, and the content thereof is 0.1 to 1.0 g per 1 L of solvent. At this time, when the content of the photoinitiator is less than 0.1 g / L, the graft ratio between the monomer and the membrane is lowered, when the content of the photoinitiator exceeds 1.0 g / L, the amount of photoinitiator required for the reaction is reduced due to the radical reaction of the photoinitiator itself is not preferable.

In the present embodiment, the solvent of the impregnation solution may be evaporated at 40 to 80 ° C., and the solvent may be used as long as it is a solvent capable of dissolving the compound having a hydrophilic functional group and a photoinitiator. In the embodiment of the present invention, an alcohol solvent is preferably used as the solvent of the impregnation solution, and an example thereof is any one selected from the group consisting of methyl alcohol, ethyl alcohol, propyl alcohol and isopropyl alcohol.

In the embodiment of the present invention, the conveying speed of the polyvinylidene fluoride membrane to be transported into the primary impregnation device 200 is preferably a rate at which the polyvinylidene fluoride membrane can be sufficiently impregnated in the impregnation solution, In the examples, the thickness is 0.5 to 5 m / min.

Next, the pore suction device 300 is a plurality of the impregnation solution attached to the surface of the polyvinylidene fluoride membrane during the first impregnation in the impregnation solution in the primary impregnation device 200 is provided with a plurality of polyvinylidene fluoride membrane Fill in the internal pores of the.

The acrylic monomers used in the examples of the present invention are generally present in the liquid phase at room temperature, but with respect to the hydrophobic polyvinylidene fluoride membrane surface, it is difficult to evenly disperse the membrane pores evenly. The pore suction device 300 of the present invention can evenly disperse the impregnating solution containing the acrylic monomer and the photoinitiator not only into the membrane surface, but also into the internal pores, thereby achieving a high graft rate which cannot be reached by simply performing an impregnation process. To achieve.

As shown in FIG. 2, the pore suction device 300 according to the exemplary embodiment of the present invention includes a suction pipe 310 and an air inlet device 320.

The suction pipe 310 is disposed to cross the transport path of the polyvinylidene fluoride membrane, and the air inlet device 320 is provided at one side of the suction pipe 320 to introduce air into the suction pipe 320.

Looking at the operation of the pore suction device 300 according to an embodiment of the present invention, the polyvinylidene fluoride membrane first impregnated in the impregnation solution in the primary impregnation device 200 is the suction pipe ( In contact with 310, the air inlet device 320 of the pore suction device 300 flows air from the outside, and passes the air passing through the suction pipe 310 in the direction of the arrow of FIG. Let's go. As such, when the air passes through the inside of the suction pipe 310, the pressure decreases on the surface where the speed of the fluid increases, and according to the Bernoulli principle in which the fluid flows from the high pressure to the low pressure, polyvinyl The impregnation solution attached to the surface of the lithium fluoride membrane is filled into a plurality of internal pores provided in the polyvinylidene fluoride membrane. That is, since the inside of the suction tube 310 of the present invention has a low pressure and the outside of the polyvinylidene fluoride membrane located outside the suction tube 310 maintains an atmospheric pressure, the impregnation solution existing outside the polyvinylidene fluoride membrane This is introduced into the internal pores.

On the other hand, the outside of the suction tube 310 of the pore suction device 300 according to an embodiment of the present invention may further include a porous suction tube 330 surrounding it as shown in FIG. In this case, the suction pipe 310 and the porous suction pipe 330 together constitute a pore suction unit, the cross-sectional view of the pore suction unit is as shown in FIG.

1 again, the secondary impregnation device 400 re-uses the polyvinylidene fluoride membrane in which the impregnation solution is sucked into the pores in the pore suction device 300 in the impregnation solution containing a compound having a hydrophilic functional group and a photoinitiator. Impregnate In this case, the same impregnation solution as the impregnation solution used in the primary impregnation device 200 may be used as the impregnation solution. In the embodiment of the present invention, the impregnation solution is impregnated by the secondary impregnation device 400 with the impregnating solution again to the outer surface of the polyvinylidene fluoride membrane filled in the inner pores, so that the polyvinylidene fluoride membrane inside the pore And the outside can be sufficiently impregnated with the impregnation solution.

The solvent volatilization apparatus 500 volatilizes and removes the solvent of the solution impregnated into the polyvinylidene fluoride membrane secondary impregnated by the secondary impregnation apparatus 400. The solvent volatilization apparatus 500 of the embodiment of the present invention removes the alcohol solvent except the acrylic monomer and photoinitiator contained in the impregnation solution. The solvent volatilization device 500 according to the embodiment of the present invention for removing the solvent includes a heat source capable of heating a temperature sufficient to volatilize the solvent of the impregnation solution. In this embodiment, an infrared heater may be used as such a heat source, and the alcohol solvent is volatilized and removed by applying heat of 30 to 80 ° C. through the infrared heater. The infrared heater is then provided at both the top and bottom of the transport path of the polyvinylidene fluoride membrane so that solvent volatilization occurs at both the top and bottom of the polyvinylidene fluoride membrane.

The reaction device 600 applies energy to the polyvinylidene fluoride membrane in which the solvent is volatilized by the solvent volatilization device 500 to cause a graft reaction. To this end, the reaction device 600 includes a light source capable of irradiating light of energy that can cause a reaction of the photoinitiator. In the embodiment of the present invention, such a light source includes a high energy density UV lamp (not shown) of 100 mW / cm or more. At this time, the light source is provided at both the upper and lower portions of the transport path of the polyvinylidene fluoride membrane so that the graft reaction occurs at both the upper and lower portions of the polyvinylidene fluoride membrane.

 The reactor 600 irradiates UV rays through a light source for 1 second to 10 minutes to perform graft polymerization of an acrylic monomer inside and on the surface of the pores of the solvent-volatile polyvinylidene fluoride membrane.

At this time, 2,2-dimethoxy-2-2-phenylacetophenone, which is a photoinitiator used in the embodiment of the present invention, is decomposed into radicals at 90 to 120 ° C., and the half-life is about 1 to 20 minutes. In accordance with this, the graft ratio can be appropriately adjusted.

Therefore, in the present invention, the preferred polymerization time is 1 second to 10 minutes, but if the polymerization time is less than 1 minute, it is difficult to obtain a polymer having an appropriate graft ratio. This lowers the self-polymerization of the monomer more easily than the graft polymerization, which also lowers the graft rate.

The light source of light irradiation used in the graft polymerization in the present invention may provide a continuous spectrum of wavelengths, a series of peaks or a single emission line. Preferred light sources may be any one selected from the group consisting of vacuum UV irradiation, high power UV irradiation, broadband UV irradiation, and black body UV irradiation.

As the UV light source, it is preferable to be able to perform irradiation with broadband. For example, the broadband may include a wavelength distribution in the UV band of the wavelength range of 100nm to 400nm, for example, the band of 150nm to 350nm.

On the other hand, the light source may include a narrower band region of irradiation, for example, wavelength distribution within 100 to 200nm, 200 to 280nm, 280 to 315nm and 315 to 400nm, UV light source is not limited to this, more various It may be divided into an irradiation wavelength region.

Further, the intensity or power density of the pulsed light source is about 100 to 1000 mW / cm at a treatment time of 1 second to 300 seconds, preferably 1 second to 120 seconds, more preferably 1 second to 60 seconds. Such a light source can deliver irradiation pulses in a short burst, and the pulsed light source has sufficient energy and can deliver high density irradiation. Most preferably, the light source is a light source capable of pulsed broadband and blackbody irradiation as described in US Pat. No. 5,789,755.

 The reactant removal apparatus 700 impregnates and washes the polyvinylidene fluoride membrane in which the graft reaction is completed in the reaction apparatus 600 to remove unreacted reactants.

Drying apparatus 800 removes the adhered residues upon washing the polyvinylidene fluoride membrane in reactant removal apparatus 700. To this end, the drying apparatus 800 may include an infrared heater (not shown). The infrared heater is then provided at both the top and the bottom of the transport path of the polyvinylidene fluoride membrane to allow drying to occur at both the top and bottom of the polyvinylidene fluoride membrane.

The winding device 900 winds and discharges the polyvinylidene fluoride membrane dried by the drying device 900.

As described above, the polyvinylidene fluoride membrane surface modification apparatus according to an embodiment of the present invention first impregnates the porous polyvinylidene fluoride membrane and then attaches the impregnation solution attached during the first impregnation through the pore suction device. By forcibly filling into the pores therein, the inside of the membrane is filled with the impregnation solution, and the membrane surface is refilled through the secondary impregnation to sufficiently supply the impregnation solution to the inside and the surface of the porous polyvinylidene fluoride membrane. Therefore, according to the polyvinylidene fluoride membrane surface modification apparatus according to an embodiment of the present invention, the hydrophilic functional groups contained in the impregnation solution can be graft-polymerized not only on the surface of the polyvinylidene fluoride membrane but also inside the pores. Not only can the hydrolyzed fluoride membrane be sufficiently hydrophilic, but also porous, so that the water permeability can be achieved.

As described above, the polyvinylidene fluoride membrane surface modification apparatus of the present invention fills the impregnating solution containing the acrylic monomer and the photoinitiator to the inside of the pore as well as the surface of the polyvinylidene fluoride membrane through a pretreatment process before light irradiation. Thereafter, by irradiating with light, the hydrophilic functional group can be graft-polymerized not only on the surface of the polyvinylidene fluoride membrane but also on the inside of the pore to improve the surface hydrophilicity and shorten the impregnation time.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited thereto, and various modifications can be made within the scope of the technical idea of the present invention, and it is natural that the present invention belongs to the appended claims. Do.

Claims (15)

A primary impregnation apparatus for impregnating a porous polyvinylidene fluoride membrane having a plurality of pores in the impregnation solution; A pore suction device filling the impregnation solution into the pores of the porous polyvinylidene fluoride membrane; And A reaction apparatus for performing a surface modification reaction by irradiating the impregnated porous polyvinylidene fluoride membrane with light; Polyvinylidene fluoride membrane surface modification apparatus comprising a. The method of claim 1, The impregnation solution is a polyvinylidene fluoride membrane surface modification apparatus, characterized in that prepared by dissolving a compound having a hydrophilic functional group and a photoinitiator in a volatile solvent. The method of claim 2, And said compound is an acrylic monomer selected from the group consisting of acrylic acid, methacrylic acid and glycidyl methacrylate. The method of claim 2, And said photoinitiator is 2,2-dimethoxy-2-phenylacetophenone. The method of claim 2, And said volatile solvent is an alcohol solvent selected from the group consisting of methyl alcohol, ethyl alcohol, propyl alcohol and isopropyl alcohol. The method of claim 1, The pore suction device A suction tube disposed across the transfer path of said polyvinylidene fluoride membrane; And An air inlet device provided at one side of the suction pipe to introduce air into the suction pipe; The polyvinylidene fluoride membrane surface modification apparatus comprising a. The method of claim 6, The pore suction device The polyvinylidene fluoride membrane surface modification apparatus further comprises a porous suction tube surrounding the suction tube outside the suction tube. The method of claim 1, A secondary impregnation device for impregnating the porous polyvinylidene fluoride membrane filled with the impregnation solution into the pores in the pore suction device again with the impregnation solution; The polyvinylidene fluoride membrane surface modification apparatus further comprises. The method of claim 2, A solvent volatilization device comprising a heat source providing a temperature condition sufficient to volatilize the volatile solvent; The polyvinylidene fluoride membrane surface modification apparatus further comprises. The method of claim 9, And the heat source is provided above and below the transport path of the polyvinylidene fluoride membrane. The method of claim 2, The reactor is And a light source for irradiating light for decomposing the photoinitiator into radicals. The method of claim 11, And the light source is provided above and below the transport path of the polyvinylidene fluoride membrane. The method of claim 1, A reactant removal device for washing the polyvinylidene fluoride membrane in which the reaction is completed in the reaction device; The polyvinylidene fluoride membrane surface modification apparatus further comprises. The method of claim 13, A drying device for removing water used for washing in the reactant removing device; The polyvinylidene fluoride membrane surface modification apparatus further comprises. The method according to any one of claims 1 to 14, And said pore size is in the range of 0.1 to 10 [mu] m.

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