KR20160057672A - Polyamide thin-film composite membrane with dicarboxylic acid, and manufacturing method thereof - Google Patents

Abstract

The present invention relates to a complex membrane which improves a hydrophilic property thereof by manufacturing a PA layer having an excellent polarity on a porous support, and a method for manufacturing the same. The separation membrane may be manufactured through the steps of: immersing a porous support in an aqueous polymer solution in which an aqueous polymer is dissolved in distilled water; drying the support immersed in the aqueous polymer solution; immersing the dried support in an organic polymer solution in which an organic polymer is dissolved in an aliphatic hydrocarbon solvent; and drying the support immersed in the organic polymer solution.

Description

TECHNICAL FIELD The present invention relates to a polyamide composite membrane containing a carboxyl group, a polyamide composite membrane using the same,

The present invention relates to a carboxyl-containing polyamide composite membrane and a method of preparing the same, and more particularly, to a PA-polyamide composite membrane having improved polarity and improved hydrophilicity of a composite membrane A composite membrane and a manufacturing method thereof.

The preparation of membranes using polymeric materials is generally made using the dry-wet phase inversion method. The dry-wet phase transition method is a method for producing a gas separation membrane by solidifying a polymer by inducing a solvent evaporation rate in a dope solution composed of a polymer, a solvent and an additive.

The intrinsic performance required as a gas separation membrane is high permeability and selectivity. However, in general, high permeability membranes have low selectivity and high selectivity membranes have low permeability. Since polymer membranes have problems in terms of heat resistance, chemical resistance and durability, studies for developing polymer membranes having high efficiency and high performance have been actively carried out. That is, it is possible to improve the performance by changing the chemical structure of the membrane such as copolymerization, a polymer blend, a stereocomplex, a composite membrane using a crosslinked structure in which an ion, a polar group or a hydrophilic group is introduced, or a physical method such as a change in film formation and spinning conditions, Research is being carried out to try to make it more sophisticated.

Among them, the thin film composite (TFC) using ultra thin film is advantageous in that it exhibits high selectivity for moisture and specific gas depending on the functional group as well as improvement of low transmittance which is the biggest defect in the process using a separator. And composite membranes prepared by chemical bonding are applied to various fields because they can produce separators having excellent chemical resistance, heat resistance and durability as compared with composite membranes coated by physical methods.

In the case of manufacturing a thin film composite membrane using interfacial polymerization on the surface of a conventional membrane, a hydrophilic polyamide (PA) layer is prepared by reacting m-phenylene diamine (MPD) with trimethoyl chloride (TMC) Seawater desalination, and pressure delay osmosis.

Korean Patent Publication No. 10-2013-0030954

It is an object of the present invention to provide a polyamide composite membrane having a carboxyl group and a method of manufacturing the same, which has a PA layer excellent in polarity on a porous support to improve the hydrophilicity of the composite membrane have.

In order to accomplish the above object, the present invention provides a composite membrane comprising a porous support made of a glass-like polymer and having a water-soluble polymer interfacial surface to form a selective layer of a polyamide containing a carboxyl group

Wherein the organic polymer is composed of any one selected from polysulfone, polyisocyanate, polyimide, polyetherimide, polypropylene, and PVDF.

The aqueous polymer may be 3,5-diaminobenzoic acid or 1,3-cyclohexanebis (methylamine).

The composite membrane may be made of a flat membrane or a hollow fiber membrane.

According to another aspect of the present invention, there is provided a composite membrane producing method for producing the above composite membrane, comprising the steps of: immersing a porous support in an aqueous polymer solution in which an aqueous polymer is dissolved in distilled water; Drying the support immersed in the aqueous polymer solution; Immersing the dried support in an organic polymer solution in which an organic phase polymer is dissolved in an aliphatic hydrocarbon solvent; And drying the support immersed in the organic phase polymer solution.

Further, the method further comprises a step of heat-treating the ground body after immersing in the organic phase polymer solution.

The aliphatic hydrocarbon solvent is n-hexane.

The organic phase polymer is characterized by being dissolved in an aliphatic hydrocarbon solvent in an amount of 0.1 to 1.0 wt.%.

The aqueous polymer is characterized by being dissolved in distilled water at 0.5 to 5.0 wt.%.

Through the present invention, it is possible to produce a polyamide composite membrane having improved hydrophilicity.

1 is a chemical structural formula for the interfacial polymerization using 3,5-diamino benzoic acid and TMC.
2 is a chemical structural formula for interfacial polymerization using 1,3-cyclohexanebis (methylamine) and TMC.
FIG. 3 is a photograph of a cross-section of a composite membrane prepared by interfacial polymerization using 3,5-diamino benzoic acid and TMC using SEM.
FIG. 4 is a photograph of the cross section of the composite membrane prepared by interfacial polymerization using 1,3-cyclohexanebis (methylamine) and TMC using SEM.
FIG. 5 is a photograph of a section of a composite membrane prepared by interfacial polymerization using m-phenylene diamine and TMC using SEM.
FIG. 6 shows the results of FT-IR analysis of the composite membrane prepared by interfacial polymerization of 3,5-diamino benzoic acid and 1,3-cyclohexanebis (methylamine) with TMC and the surface of the composite membrane according to the prior art.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. In the drawings, the same reference numerals are used to designate the same or similar components, and the same reference numerals will be used to designate the same or similar components. Detailed descriptions of known functions and configurations are omitted.

In the present invention, an interfacial polymerization method for improving the hydrophilicity of a composite membrane by preparing a coating layer having an excellent polarity on a porous support, and characteristics of a composite membrane produced through such a process will be described.

The coating layer includes an amine group (-NH) and a carboxyl group (-COOH). The formation of a coating layer by interfacial polymerization can be applied to a separator made of a glassy polymer used for general polymer separator such as polysulfone, polyisocyanate, polyimide, polyetherimide, polypropylene and PVDF , And the shape of the support can be applied to both of the hollow fiber membrane and the flat membrane. Interfacial polymerization can be carried out by using TMC or CC as an organic phase polymer using 3,5-DABA and 1,3-CHMA as an aqueous polymer.

The porous separator used as a support in the present invention may be manufactured in the form of a flat membrane and a hollow fiber membrane. As the polymer material constituting the porous separation membrane, a polymer material such as polysulfone, polyethersulfone (PES), polyimide series, polyetherimide (PEI), polypropylene (PP) A glassy polymer used in general polymer separation membranes such as PVDF (polyvinylidene difluoride) and the like can be used.

In the present invention, 3,5-diaminobenzoicacid (3,5-DABA) and 1,3-cyclohexanebis (methylamine) (1,3-CHMA), which are used as an aqueous polymer, When compared with MPD, which is mainly used for polymerization, the affinity for polar gas and moisture is increased because the carboxyl group (-COOH) contained in the product is present after the reaction.

Therefore, when interfacial polymerization is carried out on the surface of the separator using the present invention, a PA layer having cross-linking with improved polarity than m-phenylene diamine (MPD) A separator having improved hydrophilicity of the composite membrane can be produced.

An organic phase monomer was prepared by using 3,5-diamino benzoic acid (3,5-DABA) and 1,3-cyclohexanebis (methylamine) (1,3-CHMA) as aqueous phase monomers. (TMC) and cyanuric chloride (CC) to prepare an ultra-thin selective layer on the surface of the support. TMC and CC, which are used as organic polymers, are being applied to various polymer synthesis because they are low in cost and excellent in chemical and thermal selective reactivity.

Since the polyamide layer prepared by the interfacial polymerization on the surface of the thus prepared ultra thin film composite film (TFC) is hydrophilic, the coating layer has a high polarity and thus can be used as CO ₂ , SO ₂ , H ₂ S It is expected that the improvement in permeability in the separation of acidic gas and water and the improvement in selectivity in gas separation with non-condensable, non-polarity gas such as H ₂ , He, N ₂ and O ₂ do.

The hydrophilic composite membranes prepared by interfacial polymerization can be applied not only as gas separation membranes but also as reverse osmosis membranes for water treatment membranes, salinity generation, and seawater desalination.

Hereinafter, a process for producing a composite membrane having a selective layer containing an amine group (-NH) and a carboxyl group (-COOH) as described above will be described with reference to examples.

[Example 1]

First, a composite film having a selective layer using 3,5-DABA will be described.

Prepare 3,5-DABA by dissolving 0.5 to 5.0 wt.% In distilled water, then immerse the porous support for 1 to 10 minutes. Thereafter, the immersed porous support is dried for 2 to 5 minutes.

The dried porous support is immersed in TMC or CC dissolved in 0.1 to 1.0 wt.% Of n-hexane, which is an aliphatic hydrocarbon solvent, for about 1 to 10 minutes. Membranes prepared after a certain period of time are dried at room temperature for 1 to 3 hours and heat-treated at 70 to 80 ° C for 10 minutes for chemical stabilization. At this time, the thickness of the coating layer formed according to the concentration and the time of the impregnation solution can be adjusted, and thus the permeability and selectivity for the target gas and liquid can be determined. The chemical structural formula for the interfacial polymerization thus prepared is shown in Fig.

[Example 2]

Next, a composite film having a selective layer using 1,3-CHMA will be described. Prepare 1,3-CHMA by dissolving 0.5 to 5.0 wt.% In distilled water, then immerse the support for 1 to 10 minutes. Thereafter, the immersed porous support is dried for 2 to 5 minutes.

The dried porous support is immersed in TMC or CC dissolved in 0.1 to 1.0 wt.% Of n-hexane for 1 to 10 minutes. Membranes prepared after a certain period of time are dried at room temperature for 1 to 3 hours and heat-treated at 70 to 80 ° C for 10 minutes for chemical stabilization. At this time, the thickness of the coating layer formed according to the concentration and the time of the impregnation solution can be adjusted, and thus the permeability and selectivity for the target gas and liquid can be determined. The chemical structural formula for the interfacial polymerization thus prepared is shown in FIG.

If the concentration of the water-borne polymer (3,5-DABA or 1,3-CHMA) is less than 0.5 wt.%, It is difficult to form a complete coating layer on the entire surface of the support because the reaction with the organic polymer is not completed. As a result, defects are generated at portions where the hydrophilic selective layer is not formed, and the degree of separation of the mixed gas is decreased.

As the concentration of the aqueous polymer increases, the hydrophilic property of the selective layer produced by the interfacial polymerization with the organic polymer is increased, but the thickness of the selective layer is also increased. At this time, if the concentration of the water-soluble polymer (3,5-DABA or 1,3-CHMA) is greater than 5.0 wt.%, The influence of the permeability decreased by the increase of the thickness of the selective layer becomes larger than the permeability improved by hydrophilicity The transmittance and the selectivity are reduced.

If the reaction time of the aqueous polymer is less than 1 minute, interfacial polymerization does not occur stably on the surface of the support. If the reaction time of the aqueous polymer is longer than 10 minutes, the aqueous polymer used for reaction with the organic polymer is exceeded and the performance is not improved.

When the concentration of the organic polymer (TMC, CC) is less than 0.1 wt.%, It is difficult to form a complete coating layer on the entire surface of the support similarly to the case of the water polymer. As a result, defects are generated at portions where the hydrophilic selective layer is not formed, and the degree of separation of the mixed gas is decreased. If the concentration of the organic polymer is more than 1.0 wt.%, The functional group of the organic polymer remaining after the reaction with the water polymer is not oxidized, thereby blocking the pore of the selected layer. This reduces the permeability and selectivity simultaneously.

Also, when the reaction time of the organic polymer is less than 1 minute, the reaction time is not sufficient and a stable selective layer can not be formed. When the reaction time of the organic polymer is more than 10 minutes, the reaction with the water polymer can not proceed and the organic polymer is generated excessively.

The composite membranes prepared according to Example 1 and Example 2 were analyzed for their chemical characteristics by confirming the formation of a coating layer through instrumental analysis. In FIGS. 3 and 4, 3,5-DABA and 1.3-CHMA coating layers coated on the surface of the hollow fiber membrane are shown, and their thicknesses are measured at 536 nm and 171 nm, respectively. The thickness of the coating layer can be controlled by the concentration of the monomer, the reaction time, and the like.

Then, in order to identify the functional groups contained in the formed coating layer, the chemical characteristics of the surface were analyzed using FT-IR (see FIG. 6). Compared with the PES support, it was confirmed that the PA layer such as amide I (CO) group (1660 cm ^-1 ) and amide II (NH) group (1540 cm ^-1 ) were formed on the surface of the interfacially polymerized composite membrane. Compared with interfacial polymerization using MPD, the carboxyl group (-COOH) (1710-1715 cm ^-1 ) can be confirmed in the composite membrane prepared by using 3,5-DABA and 1.3-CHMA as an aqueous polymer.

Water separation experiments were conducted to compare the performance of the TFC separator. To compare the experimental results, a composite membrane was prepared by using the same polyether sulfone (PES) hollow fiber membrane as a support and a reaction time of 60 seconds at an aqueous polymer concentration of 1.0 wt.% And an organic polymer concentration of 0.1 wt.%. Here, Experimental Examples 1 and 2 are experimental results of the composite membranes prepared in Examples 1 and 2, respectively.

As a comparative example, a composite membrane was prepared using polyether sulfone (PES) hollow fiber membrane as a support, MPD as an aqueous polymer, and TMC as an organic polymer, under the same conditions as in Experimental Example.

The inner and outer diameters of the manufactured hollow fiber membrane supporter were 686 μm and 1000 μm, respectively. The thickness of the selective layer in Example 1 was 536 μm, the thickness of the selective layer in Example 2 was 171 μm, Respectively.

Experiments were conducted under the same conditions using a water / N ₂ mixed gas at a temperature of 30, a pressure of 2 bar and a relative humidity of 30%. The results are shown in Table 1. The composite membrane prepared according to the present invention has improved performance (transmittance / selectivity) compared to a polyamide composite membrane prepared by interfacial polymerization of MPD and TMC, which has been mainly applied to water treatment membranes and moisture removal membranes.

division Water vapor
[GPU] N ₂
[GPU] Water vapor / N ₂
Selectivity Comparative Example 623.1 20.1 33.6 Experimental Example 1 1931.0 14.7 131.4 Experimental Example 2 1040.3 5.5 189.1

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the appended claims. It can be understood that

Claims (9)

Characterized in that a selective layer of a polyamide containing a carboxyl group is formed by interfacial polymerization of an aqueous polymer on the surface of a porous support made of a glass-like polymer.
The composite membrane according to claim 1, wherein the organic polymer is one selected from the group consisting of polysulfone, polyisocyanate, polyimide, polyetherimide, polypropylene, and PVDF.
The composite membrane according to claim 1, wherein the water polymer is 3,5-diaminobenzoic acid or 1,3-cyclohexanebis (methylamine).
The composite membrane according to claim 1, wherein the composite membrane is a flat membrane or a hollow fiber membrane.
A composite membrane manufacturing method for producing a composite membrane according to any one of claims 1 to 4,
Immersing a porous support in an aqueous polymer solution in which an aqueous polymer is dissolved in distilled water;
Drying the support immersed in the aqueous polymer solution;
Immersing the dried support in an organic polymer solution in which an organic phase polymer is dissolved in an aliphatic hydrocarbon solvent; And
And drying the support immersed in the organic phase polymer solution.
6. The method of claim 5,
Further comprising the step of heat-treating the ground body after immersing in the organic phase polymer solution.
6. The method of claim 5,
Wherein the aliphatic hydrocarbon solvent is n-hexane.
6. The method according to claim 5, wherein the organic polymer is dissolved in an aliphatic hydrocarbon solvent in an amount of 0.1 to 1.0 wt.%.
6. The method according to claim 5, wherein the aqueous polymer is dissolved in distilled water at 0.5 to 5.0 wt.%.

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