KR20180034861A - Composition for coating support material, method for preparing separation membrane using the same and separation membrane - Google Patents

Abstract

According to the present invention, provided are composition for coating supporter having excellent water permeability and salt removal rate, a method for manufacturing a separation film using the same, and a separation film. To this end, the composition according to the present invention comprises: 10-25 wt% of surfone-based resin; 70-89.5 wt% of first solvent; and 0.1-5 wt% of acetated methyl cellulose.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composition for supporting a substrate,

The present invention relates to a composition for supporting substrate coating, a method for preparing a membrane using the same, and a membrane.

With the development of the industry and population growth, interest in efficient water use and treatment technologies is increasing. In recent years, membrane technology has been increasingly applied to ensure water quality stability in water treatment, under-wastewater treatment, and seawater desalination.

Membrane is semi-permeable membrane for removing various substances in raw water. Microporous membranes are classified into microfiltration membrane, ultrafiltration membrane, nanofiltration membrane and reverse osmosis membrane depending on pore size.

Among them, the nanofiltration membrane or the reverse osmosis membrane is composed of a supporting layer and an active layer having a separating function, and the reverse osmosis membrane is mainly used for the production of ultrapure water of a semiconductor process and desalination of seawater.

There is an effort to increase the salt removal rate of the nanofiltration membrane or the reverse osmosis membrane. However, in this case, there is a problem that the water permeability is lowered, and conversely, when the water permeability is increased, the salt removal rate is lowered.

Therefore, a separation membrane having excellent water permeability and salt removal ratio is required.

It is an object of the present invention to provide a composition for a support coating composition which is excellent in water permeability and salt removal ratio, a separation membrane production method using the same, and a separation membrane.

The above and other objects of the present invention can be achieved by the present invention described below.

One aspect of the invention relates to compositions for backcoat coating.

According to one embodiment, the composition for supporting substrate coating comprises 10 to 25% by weight of a sulfonic resin, 70 to 89.5% by weight of a first solvent, and 0.1 to 5% by weight of acetylated methylcellulose.

The first solvent may include at least one of N, N-dimethylformamide, N-methyl-2-pyrrolidone, dimethylsulfoxide and dimethylacetamide.

The sulfonic resin may have a weight average molecular weight of 10,000 to 100,000.

Another aspect of the present invention relates to a method for producing a membrane.

According to one embodiment, the separation membrane manufacturing method comprises the steps of stirring the composition for supporting substrate coating, coating the composition on the surface of the substrate to form a support layer, And a second solution containing a halide in this order to form an active layer by interfacial polymerization.

In the separation membrane production method, the stirring may be performed at 20 캜 to 80 캜.

In another embodiment, the separation membrane manufacturing method may further include the steps of stirring the support-coating composition and thereafter removing the bubbles before coating the support surface.

The supporting material may be a nonwoven fabric.

The nonwoven fabric may include synthetic fibers comprising at least one of polyester, polypropylene, nylon, and polyethylene; Or a natural fiber including a cellulose system.

In the separation membrane production method, the first solution may include a polyamine and water.

In the separation membrane production method, the second solution may include a polyfunctional acyl halide and a second solvent.

Another aspect of the present invention relates to a separation membrane.

According to one embodiment, the separation membrane may be manufactured by the separation membrane production method, and the water permeability may be 10 LMH / bar or more and the salt removal ratio may be 95.0% or more.

The separation membrane may be a reverse osmosis membrane.

The reverse osmosis membrane may have a fraction molecular weight of 500 Da or less.

In another embodiment, the separation membrane has a structure in which a nonwoven fabric, a support layer, and an active layer are sequentially laminated, the support layer is porous, and includes a sulfone resin and acetylated methyl cellulose, and the active layer includes a polyamide.

The weight ratio of the sulfone resin to methyl cellulose acetylated may be 2: 1 to 250: 1.

The separation membrane is a reverse osmosis membrane, and has a water permeability of 10 LMH / bar or more, a salt removal rate of 95.0% or more, and a fraction molecular weight of 500 Da or less.

The present invention provides a composition for a substrate for re-coating having excellent water permeability and salt removal rate, a method for producing a membrane using the same, and a membrane.

FIG. 1 is a cross-sectional view of a separation membrane according to an embodiment of the present invention.

Hereinafter, the present invention will be described in more detail.

In the following description of the present invention, detailed description of known related arts will be omitted when it is determined that the gist of the present invention may be unnecessarily obscured by the present invention.

In the case where the word 'includes', 'having', 'done', etc. are used in this specification, other parts can be added unless '~ only' is used. Unless the context clearly dictates otherwise, including the plural unless the context clearly dictates otherwise.

Also, in interpreting the constituent elements, even if there is no separate description, it is interpreted as including the error range.

In the present specification, 'X to Y' representing the range means 'X or more and Y or less'.

Composition for supporting substrate coating

The composition for supporting coating according to one embodiment of the present invention comprises 10 to 25% by weight of a sulfonic resin, 70 to 89.5% by weight of a solvent and 0.1 to 5% by weight of acetylated methyl cellulose.

Hereinafter, each component of the composition for a substrate coating composition will be specifically described.

The sulfone-based resin may include polysulfone, polyethersulfone, or a combination thereof.

The sulfonic resin has a high hydrophilicity but does not melt even when exposed to water for a long period of time. Therefore, it is possible to greatly reduce the fouling phenomenon in which contaminants are adsorbed on the surface of the separator while improving the water permeability of the separator There is an advantage.

The sulfonic resin may have a weight average molecular weight of 10,000 to 100,000, specifically 20,000 to 80,000. The mechanical properties and chemical resistance of the separator are excellent in the weight-average molecular weight range.

The sulfonic resin may be contained in the composition for supporting substrate coating in an amount of 10 to 25% by weight, specifically 12 to 23% by weight. If the content of the sulfonic resin in the composition for supporting substrate coating is less than 10% by weight, macropores may be formed and the active layer may not be uniformly formed or the support layer may not be formed easily. If the content of the sulfonic resin in the composition for supporting substrate coating is more than 25% by weight, the pores formed in the support layer may become very small and water treatment efficiency may be lowered.

The first solvent can sufficiently dissolve the sulfone resin contained in the composition for coating the backing layer, and can impart an appropriate viscosity required for coating the backing layer.

The first solvent may include, for example, at least one of N, N-dimethylformamide, N-methyl-2-pyrrolidone, dimethylsulfoxide and dimethylacetamide.

The first solvent may be contained in the support coating composition in an amount of 70 to 89.5% by weight, specifically, 72 to 86% by weight. When the first solvent in the composition for support coating is contained in an amount less than 70% by weight, the flowability of the composition may be lowered, and accordingly, the stirring temperature must be increased. In addition, if the content of the first solvent in the composition for supporting coating material is more than 89.5% by weight, the pores formed in the support layer become very large and the water treatment performance may be deteriorated.

The above-mentioned acetylated methylcellulose is included in the composition for coating the backing layer and serves to improve the hydrophilicity of the backing layer coating. Acetylated methylcellulose having a large number of hydrophilic groups can effectively impart hydrophilicity to the backing coating and can improve the water permeability of the backing coating and prevent deterioration of the water permeability even when the salt removal ratio of the separation membrane is improved have. Specifically, the separation membrane formed of the composition for supporting substrate coating containing the acetylated methylcellulose can improve the salt removal rate without lowering the water permeability.

The acetylated methyl cellulose may be contained in the composition for supporting substrate coating in an amount of 0.1 to 5% by weight, specifically 0.1 to 3% by weight, more specifically 0.1 to 2% by weight. If the acetylated methyl cellulose content is less than 0.1% by weight, the effect of improving the hydrophilicity is insufficient and the water permeability is lowered or the salt removal rate is lowered by increasing the water permeability. If the acetylated methyl cellulose content is more than 5 wt%, the polymer is not completely dissolved.

The support coating composition may further include a hydrophilic polymer additive for improving hydrophilicity, an organic acid phase coagulation catalyst for facilitating phase transition, and the like. When these hydrophilic polymer additives and organic acid phase coagulation catalysts are added, the addition amount thereof may be 10 parts by weight or less based on 100 parts by weight of the first solvent so as not to deteriorate the physical properties of the reinforcing agent or the filtration membrane containing the same .

Membrane manufacturing method

The method for preparing a separation membrane according to one embodiment of the present invention includes the steps of stirring the composition for supporting substrate coating, coating the composition on the surface of the substrate to form a supporting layer, And a second solution containing an acyl halide are sequentially contacted to form an active layer by interfacial polymerization.

The step of stirring the support coating composition is a step of sufficiently dissolving and / or mixing the components of the composition in a solvent, wherein the stirring is carried out at a temperature of from 10 캜 to 80 캜, specifically from 20 캜 to 60 캜, for from 4 hours to 8 hours . ≪ / RTI > In this temperature range, the components of the backing coating composition are not damaged or changed and can be sufficiently mixed.

The step of forming the support layer by coating the composition on the surface of the support material may be performed by casting or coating the support material composition on the support material and immersing the composition in a non-solvent to solidify the sulfonic resin.

The supporting material may be a nonwoven fabric. The nonwoven fabric may specifically be a synthetic fiber comprising at least one of polyester, polypropylene, nylon and polyethylene, or a natural fiber including a cellulose system.

The active layer may be formed by interfacial polymerization by sequentially bringing the first solution and the second solution into contact with the surface of the support layer formed on the support material. Specifically, the active layer may include a polyimide by interfacial polymerization of the first solution and the second solution.

When the first solution and the second solution are sequentially brought into contact with the surface of the hollow support layer as described above, interfacial polymerization is performed on the surface of the support layer, and the active layer can be formed on the surface of the support layer by the interfacial polymerization. The active layer may include a polyamide formed by interfacial polymerization of the first solution and the second solution.

When the surface of the support layer is coated by contacting the first solution and the second solution after the formation of the support layer as described above, a coating layer can be uniformly formed on the surface of the support layer, and an active layer having a uniform thickness after the solidification step is formed on the surface of the support layer .

The first solution may comprise a polyamine and water.

The polyamine may include, but is not necessarily limited to, at least one of phenylene diamine, cyclohexanediamine, and piperazine. The polyamine may be contained in an amount of 0.1 to 15% by weight based on the total weight of the first solution. The first solution may further include a polar solvent. The polar solvent may be an ethylene glycol derivative, a propylene glycol derivative, a 1,3-propanediol derivative, a sulfoxide derivative, a sulfone derivative, a nitrile derivative, a ketone derivative or a urea derivative.

The second solution comprises a polyfunctional acyl halide and a second solvent. Examples of the polyfunctional acyl halide include tri-mesyl chloride, isophthaloyl chloride, terephthaloyl chloride, 1,3,5-cyclohexanetricarbonyl chloride and 1,2,3,4-cyclohexanetetracarbonyl chloride And may include one or more. These may be used alone or in combination of two or more. In terms of salt removal rate, trimesoyl chloride can be used. The polyfunctional acyl halide may be used in an amount of 0.01 to 5% by weight based on the total weight of the second solution. As the second solvent, aliphatic hydrocarbons having 5 to 12 carbon atoms may be used.

The coating time of each step of the interfacial polymerization may be 10 seconds to 20 minutes. It has the advantage of being uniformly coated in the above range, and the thickness is appropriately formed.

In another embodiment, the separation membrane manufacturing method may further include the steps of stirring the support-coating composition and thereafter removing the bubbles before coating the support surface. Composition for reinforcing agent coating By removing air bubbles before coating, unintended large pore formation can be prevented, and the composition can be uniformly mixed.

Membrane

Hereinafter, the separator of the present invention will be described with reference to FIG. FIG. 1 is a cross-sectional view of a separation membrane according to an embodiment of the present invention.

The separation membrane according to one embodiment can be produced by the separation membrane production method and has a water permeability of 10 LMH / bar or more, for example, 10 LMH / bar to 200 LMH / bar, specifically 15 LMH / bar to 180 LMH / bar, more specifically 20 LMH / bar to 150 LMH / bar, and the salt removal rate is 90% or more, specifically 95.0% or more, for example 95.0% to 99.9%, more specifically 98.5% to 99.9% To 98.9% to 99.9%.

The separator of the present invention has excellent salt removal rate and can be used as a reverse osmosis membrane. Specifically, the separation membrane may be a reverse osmosis membrane having improved salt removal rate without lowering water permeability.

The reverse osmosis membrane may have a fractional molecular weight of 500 Da or less, specifically 400 Da or less, more specifically 300 Da or less. The separation membrane in the fractionated molecular weight range is suitable for use as a reverse osmosis membrane for producing ultrapure water and desalination of seawater.

1, the separation membrane 100 according to another embodiment of the present invention has a structure in which a nonwoven fabric 10, a support layer 20, and an active layer 30 are sequentially stacked, and the support layer 20 is porous , A sulfonic resin and acetylated methylcellulose, and the active layer may include a polyamide.

The nonwoven fabric 10 is substantially the same as that described in the separation membrane production method of the present invention.

The support layer 20 is porous and may specifically include pores having a size of 1 to 500 nm on the surface. The thickness of the support layer may be 1 to 500 탆, specifically 10 to 200 탆. A usable level of mechanical strength and sufficient water permeability in the range of pore size and thickness can be achieved.

In addition, the support layer 20 may be formed of a composition for supporting substrate coating comprising a sulfone resin and acetylated methyl cellulose. For example, the weight ratio of the sulfone resin to methyl cellulose acetylate is in the range of 2: 1 to 250: 1, specifically 3: 1 to 220: 1, more specifically 4: 1 to 200: 1, : 1 to 50: 1. In the above weight ratio range, the separator has an advantage of excellent water permeability and mechanical strength.

The active layer 30 includes polyimide which is interfacially polymerized by the first solution and the second solution, and is excellent in the salt removal rate.

The active layer 30 may have a thickness of 1 nm to 500 nm. The salt removal rate necessary for effective membrane separation can be achieved within the above range, and the water permeability is not low. Specifically, the active layer may have a thickness of 5 nm to 300 nm.

The separation membrane 100 has excellent salt removal rate and water permeability and can be used as a reverse osmosis membrane. Specifically, the separation membrane has a water permeability of 10 LMH / bar or more, for example, 10 LMH / bar to 200 LMH / bar, specifically 15 LMH / bar to 180 LMH / bar, more specifically 20 LMH / / bar and the salt removal rate can be 90% or more, specifically 95.0% or more, for example 95.0% to 99.9%, specifically 98.5% to 99.9%, more specifically 98.8% to 99.9% May be 500 Da or less, specifically 400 Da or less, more specifically 300 Da or less.

Hereinafter, the configuration and operation of the present invention will be described in more detail with reference to preferred embodiments of the present invention. It is to be understood, however, that the same is by way of illustration and example only and is not to be construed in a limiting sense.

The contents not described here are sufficiently technically inferior to those skilled in the art, and a description thereof will be omitted.

Example

Example  One

16% by weight of polysulfone (PSF) as a sulfonic resin and 82% by weight of N-dimethylformamide as a first solvent were mixed at room temperature or higher, 2% by weight of acetylated methyl cellulose was further mixed, Lt; / RTI > to prepare a composition for backcoat coating.

After removing the air bubbles remaining in the composition for supporting coating composition, the composition was coated on a nonwoven fabric to form a supporting layer.

The support layer was contacted with a first solution containing 2% by weight of metaphenylenediamine and 98% by weight of water and a second solution containing 0.1% by weight of trimethoyl chloride and 99.9% by weight of isoparaffin for 1 minute, The active layer was formed by polymerization.

Comparative Example  One

A separation membrane was prepared in the same manner as in Example 1, except that acetylated methylcellulose (AMC) was not included and the composition for matrix coating was applied in the amounts shown in Table 1 below.

Comparative Example  2

A separation membrane was prepared in the same manner as in Example 1, except that 7% by weight of acetylated methyl cellulose (AMC) was used and the composition for support coating was applied in the contents shown in the following Table 1.

Property evaluation method

(1) Water permeability (LMH): After the membrane was installed in a cell for measuring flow rate, it was operated for 30 minutes at a pressure of 15.5 bar using an aqueous solution of sodium chloride at 25 ° C and 2,000 ppm, The water permeability was measured and shown in Table 1 below.

(2) Salt Removal Rate (%): After separator was mounted on a cell for measuring flow rate, the conductivity of the produced water was measured after operating for 30 minutes under a pressure of 15.5 bar using an aqueous solution of sodium chloride of 2,000 ppm at 25 ° C, The salt removal rate is calculated and is shown in Table 1.

Salt removal rate (%) = (1- (Conductivity value of product water / Conductivity value of raw water) X 100

Example 1 Comparative Example 1 Comparative Example 2 PSF 16 16 16 NMP 82 84 77 AMC 2 0 7 Water Transmission (LMH) 26 30 - Salt Removal Rate (%) 99.0 98.4 -

As shown in Table 1, Example 1 containing acetylated methylcellulose (AMC) in the content of the present invention improved the salt removal ratio without lowering the water permeability, while Comparative Example 1 containing no acetylated methyl cellulose (AMC) 1 was accompanied by a decrease in the salt removal rate in order to secure water permeability, and in Comparative Example 2 containing excess acetylated methyl cellulose (AMC), measurement was impossible because the polymer was not completely dissolved.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It will be understood that the invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. It is therefore to be understood that the embodiments described above are in all respects illustrative and not restrictive.

Claims (16)

10 to 25% by weight of a sulfonic resin, 70 to 89.5% by weight of a first solvent, and 0.1 to 5% by weight of acetylated methylcellulose.
The method according to claim 1,
The composition of claim 1, wherein the first solvent comprises at least one of N, N-dimethylformamide, N-methyl-2-pyrrolidone, dimethylsulfoxide and dimethylacetamide.
The composition for supporting substrate according to claim 1, wherein the sulfonic resin has a weight average molecular weight of 10,000 to 100,000.
13. A method for preparing a composition comprising: stirring a composition of any one of claims 1 to 3;
Coating the composition on a surface of a support to form a support layer;
Forming an active layer by interfacial polymerization by sequentially contacting a first solution containing an amine and a second solution containing an acyl halide on the support layer;
≪ / RTI >
5. The method according to claim 4, wherein the stirring is performed at 20 to 80 캜.
5. The method of claim 4, further comprising the step of removing air bubbles before coating the surface of the support material after stirring the support composition for coating.
The method of claim 4, wherein the support material is a nonwoven fabric.
8. The method of claim 7,
The nonwoven fabric may include synthetic fibers comprising at least one of polyester, polypropylene, nylon, and polyethylene; Or a natural fiber including a cellulose system.
5. The method of claim 4, wherein the first solution comprises a polyamine and water.
5. The method of claim 4, wherein the second solution comprises a polyfunctional acyl halide and a second solvent.
A membrane prepared by the method of claim 4, having a water permeability of at least 10 LMH / bar and a salt removal rate of at least 95.0%.
12. The separation membrane according to claim 11, wherein the separation membrane is a reverse osmosis membrane.
12. The separation membrane according to claim 11, wherein the reverse osmosis membrane has a cut-off molecular weight of 500 Da or less.
A nonwoven fabric, a support layer, and an active layer sequentially stacked,
Wherein the support layer is porous and comprises a sulfonic resin and acetylated methylcellulose,
Wherein the active layer comprises polyamide.
15. The separation membrane according to claim 14, wherein the weight ratio of the sulfone resin to methyl cellulose acetate is 2: 1 to 250: 1.
15. The separation membrane according to claim 14, wherein the separation membrane is a reverse osmosis membrane having a water permeability of 10 LMH / bar or more, a salt removal ratio of 95.0% or more, and a fraction molecular weight of 500 Da or less.

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