KR101816814B1 - coating solution for selective separation carbon dioxide, carbon dioxide separation membrane thereof and manufacturing method thereof - Google Patents

Abstract

The present invention relates to a coating agent for a carbon dioxide separation membrane capable of selectively separating only carbon dioxide from two or more gas mixtures, a composite membrane for separating carbon dioxide using the same, and a method for producing the same.

Description

TECHNICAL FIELD The present invention relates to a coating film for a carbon dioxide separation membrane, a composite membrane for separating carbon dioxide using the same,

More particularly, the present invention relates to a coating agent for a carbon dioxide separation membrane capable of selectively separating only carbon dioxide from two or more gas mixtures, a coating film using the same, a composite membrane for separating carbon dioxide using the same, and a method for producing the same .

In general, carbon dioxide has the greatest impact on global warming among the greenhouse gases such as methane and freon gas, and strictly requires emission regulations for the whole country.

Since it is very difficult to realize the reduction of carbon dioxide emissions in each industrial sector, it was attempted to separate carbon dioxide from the discharged gas mixture. As a result, many studies on the technology of carbon dioxide capture and storage (CCS) .

The technologies for collecting carbon dioxide can be classified into wet capture, dry capture and capture using separator. Of these, capture technology using separator is advantageous in that it is easy to design and commercialize, and energy consumption is low, The most research is being done.

For example, glassy polymers of polysulfone, polyethersulfone, polyimide, polyamide, polyacrylonitrile, and polyetherimide are excellent in mechanical strength and heat resistance at high temperatures, and are chemically stable and used as a liquid or gas separation membrane However, there is a problem that the permeability is low, and rubber-like polymers such as silicon have a high permeability, but also have a problem that their mechanical strength and heat resistance are relatively low as compared with glassy polymers and their selectivity is low.

To solve these problems, various drawbacks were solved and various composite membranes were prepared using the glassy polymer and rubbery polymer. The composite membrane is a technique that is often referred to as a breakthrough in history. It is a technique frequently used to form a support layer serving as a porous support to improve mechanical stability, and has a high CO ₂ solubility and high permeability It is an anisotropic separation membrane technology which has an asymmetric structure in which a dense surface layer (toplayer) is formed by coating a material.

The composite membrane having such a structure can optimize the gas permeation selectivity and the chemical and thermal stability since the support layer and the surface layer can be optimized individually, and the production process is simple and suitable for large-scale production.

For example, a mixed membrane prepared by mixing a polymer and an inorganic material has been disclosed, which can utilize both the characteristics of a polymer and an inorganic material, and has improved permeation selectivity and mechanical strength. However, due to small pores and low pores, There is a limit to improve the performance.

On the other hand, in general, it is possible to complement the defects of the film by coating the support layer or the surface layer of the composite film, which is the active layer material used for the organic material separation or concentration, but there is a problem that the support layer and the surface layer are separated from each other due to the high- .

In addition, it has been reported that an ether group has high affinity with carbon dioxide, and a polyethylene oxide-based separator is under study. The polyethylene oxide has a crystal structure and has a low permeability.

Patent Document 1: Korean Patent Laid-Open Publication No. 10-2004-0046521

SUMMARY OF THE INVENTION Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and it is an object of the present invention to provide a composite membrane for carbon dioxide separation comprising a coating agent for a carbon dioxide separation membrane having high permeability and selectivity and a coating layer formed therefrom, I would like to.

In order to achieve the above object,

a) a polyethylene glycol-polydimethylsiloxane copolymer represented by the following formula (1);

b) tolylene-2,4-diisocyanate-terminated polyethylene glycols or polypropylene glycols represented by the following formula (2);

(Wherein n ₁ and n ₂ are an integer of 5 to 20, R ₁ is -CH ₂ CH ₂ O or -CH ₂ CHCH ₃ O, and m is an integer of 1 to 20).

c) a diisocyanate chain extender; And

and d) a urethane reaction catalyst.

The diisocyanate chain extender may be any one selected from the group consisting of tolylene diisocyanate, isophorone diisocyanate, methylene diisocyanate, methylene diphenyl diisocyanate, hexamethylene diisocyanate, xylene diisocyanate and tolylidine diisocyanate .

The urethane reaction catalyst is selected from the group consisting of tin (II) acetate, tin (II) octoate, tin (II) ethylhexoate, tin (II) laurate, dibutyltin diacetate, dibutyltin dilaurate, (N, N-dimethylaminopropyl) -s-hexahydrotriazine, tetramethylammonium hydroxide, sodium hydroxide, sodium N - [(2- hydroxy -5-nonylphenyl) methyl] -N-methylaminoacetate, sodium acetate, sodium octoate, potassium acetate, potassium octoate, and mixtures thereof.

The average molecular weight of the polyethylene glycol-polydimethylsiloxane copolymer represented by the formula (1) is 1000 to 2500, and the average molecular weight of the tolylene-2,4-diisocyanate-terminated polyethylene glycol or polypropylene glycol represented by the formula An average molecular weight of 1000-3000 and an average molecular weight of the diisocyanate chain extender of 100-300.

A polyethyleneglycol-polydimethylsiloxane copolymer represented by the formula 1, a tolylene-2,4-diisocyanate-terminated polyethylene glycol or polypropylene glycol represented by the formula 2, and a diisocyanate chain- The molar ratio is 1: 0.2-0.6: 3.3-8.0.

The present invention also provides a coating film for a carbon dioxide separation membrane, which is prepared by applying and heat-treating a coating agent for a carbon dioxide separation membrane.

The thickness of the coating film is 90 to 110 탆.

The coating film is characterized in that the selectivity of carbon dioxide with respect to nitrogen in air is 10-40.

The carbon dioxide permeability of the coating film is 400 to 1000 Barrer.

According to another aspect of the present invention, there is provided a porous polymer scaffold comprising: a porous polymer scaffold; And a coating layer formed of the coating agent on the porous polymer scaffold.

The porous polymer scaffold is any one selected from the group consisting of polyvinylidene fluoride, polysulfone, polyacrylonitrile, polyimide, polyetherimide, and polyethersulfone.

And the thickness of the coating layer is 0.5 to 2 占 퐉.

The composite membrane is characterized in that the selectivity of carbon dioxide with respect to nitrogen in air is 10 to 40.

The composite membrane has a permeability of carbon dioxide of 400 to 1000 GPU.

According to another aspect of the present invention, there is provided a method for producing a composite membrane for carbon dioxide separation comprising the steps of:

I) preparing a porous polymer scaffold,

II) forming a coating layer on the porous polymer scaffold from a coating solution in which the coating agent for carbon dioxide separation membrane is diluted with a diluent, and

III) heat treating the coating layer at 70 to 150 ° C.

The coating solution is characterized in that the concentration of the coating agent is 0.5 to 20 wt% and the concentration of the diluent is 80 to 99.5 wt%.

The coating layer in step II) is formed by spin coating, dip coating, cast coating or spray coating.

And the step II) is performed under the condition that the average relative humidity is 1 to 5%.

The urethane and urea reaction is terminated by the heat treatment in the step III), and a solidified coating layer having a physicochemical bonding structure is obtained by hydrogen bonding between hard segments of a urethane bond or a urea bond.

According to the present invention, by forming a coating layer for carbon dioxide separation having a urethane and urea structure formed through the reaction of a polyethylene glycol-polydimethylsiloxane copolymer and an isocyanate compound and a physical crosslinking structure by hydrogen bonding, permeability and selectivity to carbon dioxide Can be improved.

1 is a TGA thermal analysis graph of each of the coating film prepared from Examples 2 to 6 and the coating film prepared from Comparative Example 2. Fig.
2 is an IR analysis graph of each of the coating film prepared in Examples 2 to 6 and the coating film prepared in Comparative Example 2. Fig.
FIG. 3 is a graph showing tensile strength (stress (MPa)) according to strain rate for evaluating the mechanical properties of the coating film prepared in Examples 2 to 6 and the coating film prepared in Comparative Example 2. FIG.
FIG. 4 is a graph showing permeability (Barrer) and oxygen / nitrogen selectivity (O ₂ / N ₂ selectivity) for oxygen and nitrogen of each of the coating films prepared in Comparative Examples 1 to 5.
FIG. 5 is a graph showing permeability (Barrer) and selectivity to carbon dioxide / nitrogen (CO ₂ / N ₂ selectivity) of each of the coating films prepared in Comparative Examples 1 to 5.
FIG. 6 is a graph showing permeability (Barrer) and oxygen / nitrogen selectivity (O ₂ / N ₂ selectivity) for oxygen and nitrogen in each of the coating films prepared in Examples 2 to 6.
FIG. 7 is a graph showing the permeability (Barrer) and selectivity (CO ₂ / N ₂ selectivity) for carbon dioxide and nitrogen of each of the coating films prepared in Examples 2 to 6.
8 is an SEM photograph of the composite membrane for carbon dioxide separation prepared in Examples 7 to 11.
9 is a graph showing permeability (GPU) and oxygen / nitrogen selectivity (O ₂ / N ₂ selectivity) for oxygen and nitrogen in each of the composite membranes for separating carbon dioxide prepared in Examples 7 to 11 .
10 is a graph showing permeability (GPU) and selectivity to carbon dioxide / nitrogen (CO ₂ / N ₂ selectivity) for carbon dioxide and nitrogen of each of the composite membranes for separating carbon dioxide prepared in Examples 7 to 11 .

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

According to an aspect of the present invention,

a) a polyethylene glycol-polydimethylsiloxane copolymer represented by the following formula (1);

≪ Formula 1 >

b) tolylene-2,4-diisocyanate-terminated polyethylene glycols or polypropylene glycols represented by the following formula (2);

(2)

(Wherein n ₁ and n ₂ are an integer of 5 to 20, R ₁ is -CH ₂ CH ₂ O or -CH ₂ CHCH ₃ O, and m is an integer of 1 to 20).

c) a diisocyanate chain extender; And

d) a urethane reaction catalyst.

Specifically, the polyethylene glycol-polydimethylsiloxane copolymer represented by the formula (a) is preferably a polyethylene glycol-polydimethylsiloxane copolymer known in the art as "IM22" represented by the following formula Can be used.

(3)

At this time, the average molecular weight of the polyethylene glycol-polydimethylsiloxane copolymer represented by the formula (1) is preferably 1000 to 2500.

The tolylene-2,4-diisocyanate-terminated polyethylene glycol or polypropylene glycol represented by the above formula (b) is preferably selected from tolylene-2,4-diol represented by the following formula (4) Diisocyanate-terminated polyethylene glycols or polypropylene glycols.

[Chemical Formula 4]

[Chemical Formula 5]

(In the above formulas (4) and (5), m is an integer of 1 to 20).

Specifically, the average molecular weight of the tolylene-2,4-diisocyanate-terminated polyethylene glycol or polypropylene glycol represented by the formula (2) is 1000 to 3000.

Wherein the diisocyanate chain extender is any one selected from the group consisting of tolylene diisocyanate, isophorone diisocyanate, methylene diisocyanate, methylene diphenyl diisocyanate, hexamethylene diisocyanate, xylene diisocyanate and tolylidine diisocyanate However, considering the reactivity, isophorone diisocyanate is more preferably used.

Preferably, the average molecular weight of the diisocyanate chain extender may range from 100 to 300.

The urethane reaction catalyst is selected from the group consisting of tin (II) acetate, tin (II) octoate, tin (II) ethylhexoate, tin (II) laurate, dibutyltin diacetate, dibutyltin dilaurate, (N, N-dimethylaminopropyl) -s-hexahydrotriazine, tetramethylammonium hydroxide, sodium hydroxide, sodium N - [(2- hydroxy -5-nonylphenyl) methyl] -N-methylaminoacetate, sodium acetate, sodium octoate, potassium acetate, potassium octoate and mixtures thereof, and most preferably dibutyl You can use annotation dilate.

The catalyst may be used in an amount of 0.3 to 0.4 moles based on 1 mole of the polyethylene glycol-polydimethylsiloxane copolymer represented by Formula 1, wherein the catalyst is a polyethylene glycol-polydimethylsiloxane represented by Formula 1 When the amount of the catalyst is less than 0.3 mol based on 1 mol of the copolymer, the content of the catalyst is low, resulting in incomplete reaction and a long reaction time. If the amount exceeds 0.4 mol, addition polymerization may occur.

The molar ratio of the polyethylene glycol-polydimethylsiloxane copolymer represented by Formula 1 to the diisocyanate chain extender is preferably 1: 3.3-8.0. When the molar ratio is less than 1: 3.3, the urethane and urea The film does not have a film shape because it does not form a reaction and when it exceeds 1: 8.0, it has a brittle mechanical property with an increase in an excessive hard segment, so that it can be formed into a single film, There arises a problem in durability when the coating layer is formed.

A polyethyleneglycol-polydimethylsiloxane copolymer represented by the formula 1, a tolylene-2,4-diisocyanate-terminated polyethylene glycol or polypropylene glycol represented by the formula 2, and a diisocyanate chain- The molar ratio is preferably 1: 0.2-0.6: 3.3-8.0. When the molar ratio is less than 1: 0.2: 3.3, the reaction site which can form a urethane bond is not completely reacted to form a membrane having relatively low mechanical properties, 1: 0.6: 8.0, the tolylene-2,4-diisocyanate-terminated polyethylene glycol or polypropylene glycol interferes with the hydrogen bonding in the structure to weaken the bonding force between the chains, so that not only the mechanical properties are lowered but also the brittleness is weakened, As a result, the membrane is easily deformed, so that the selectivity to carbon dioxide for nitrogen can not be maintained, .

More preferably, the polyethylene glycol-polydimethylsiloxane copolymer represented by the formula (1), the tolylene-2,4-diisocyanate-terminated polyethylene glycol or polypropylene glycol represented by the formula 2, and the diisocyanate chain The molar ratio of the extender may be 1: 0.2-0.6: 4.05, because when the coating film prepared by mixing the coating composition prepared at the above molar ratio is used to produce a coating film having a single film structure, the selectivity of carbon dioxide 30 < / RTI > to 40 < / RTI >

Another aspect of the present invention relates to a coating film for a carbon dioxide separation membrane prepared by coating and heat-treating the coating composition for a carbon dioxide separation membrane.

Specifically, the coating film for a carbon dioxide separation membrane has a single film structure by applying the coating material for a carbon dioxide separation membrane on a substrate such as Teflon and then subjecting it to heat treatment.

Since the coating film has a tensile strength of 0.5 to 1.5 MPa, it is preferable that the coating film has a thickness of 90 to 110 탆 in order to be used as a single film structure without supporting layer.

The coating film of the thickness described above has a selectivity of 10 to 40 for carbon dioxide with respect to nitrogen in air, and such a value is measured at 25 DEG C and 2 bar.

More preferably, the coating agent used in the coating film is a polyethylene glycol-polydimethylsiloxane copolymer represented by Formula 1, tolylene-2,4-diisocyanate-terminated polyethylene glycol represented by Formula 2 or polypropylene The molar ratio of the glycol and the diisocyanate chain extender may be 1: 0.2-0.6: 4.05, because when the coating film prepared by mixing the above-mentioned molar ratio is used to prepare a coating film having a single film structure, Because the selectivity of carbon dioxide to carbon dioxide is very high, from 30 to 40.

Another aspect of the present invention relates to a porous polymer scaffold comprising: a porous polymer scaffold; And a coating layer formed on the porous polymer scaffold by the coating agent for the carbon dioxide separation membrane.

Since the coating layer formed on the porous polymer scaffold has a high affinity for carbon dioxide, the pore size of the porous polymer scaffold can be reduced, The permeability and the selectivity to carbon dioxide are increased. Therefore, the composite membrane for separating carbon dioxide having the above-described structure has excellent carbon dioxide separation performance.

The porous polymer scaffold is made of polyvinylidene fluoride (PVDF), polysulfone (PSf), polyacrylonitrile (PAN), polyimide (PI), polyetherimide (PEI) and polyethersulfone , And most preferably polyacrylonitrile (PAN) can be used.

The porous polymer scaffold may be selected from the group consisting of a spiral-wound type, a tubular type, a monolith type, a hollow-fiber type, and a plat and frame type. It is characterized by one.

When coated with the above coating, the rubbery properties of the silicone structure are affected by the increased permeability due to the high free volume and high chain flow, and the effect of the ether groups present in the poly (ethylene glycol) and polypropylene glycol structures The increased affinity of carbon dioxide increases the solubility of carbon dioxide and increases selectivity.

Also, since the composite membrane for separating carbon dioxide according to the present invention uses a coating agent having the above-described structure, the coating layer is fixed on the porous polymer scaffold together with urethane bonding, urea bonding and physical crosslinking by hydrogen bonding, , And the separation performance (selectivity and permeability) for carbon dioxide was increased.

Specifically, the composite membrane has a selectivity of carbon dioxide to nitrogen in air of 10 to 40 and a permeability of carbon dioxide of 400 to 1000 GPU. In constructing the composite membrane for separating carbon dioxide according to the present invention, The permeability is not lowered, but the carbon dioxide permeability is improved to 400 to 1000 GPU, preferably 700 to 1000 GPU, although the coating layer is clogged with the coating layer.

Particularly, the average carbon dioxide permeability of the coating film for a carbon dioxide separation membrane prepared only with the coating agent is 670 barrer, while the average carbon dioxide permeability of the composite membrane for separating carbon dioxide is 842 GPU. As compared with the use of the coating film for a carbon dioxide separation membrane, It can be confirmed that the use of the composite membrane in the form of a carbon dioxide membrane improves the average carbon dioxide permeability by 200 or more.

The thickness of the composite membrane for separating carbon dioxide (support + coating layer) may be 150 μm to 170 μm. When the thickness of the composite membrane for separating carbon dioxide is less than 150 μm, the gas permeability It can not be used for a long period of time because it is difficult to maintain the physical properties of the separator itself at high pressure. If it exceeds 200 탆, the coating layer may be formed thick on the support to significantly deteriorate the permeability to carbon dioxide. When used, the support and the coating layer can be desorbed.

Another aspect of the present invention relates to a process for producing a composite membrane for carbon dioxide separation comprising the steps of:

I) preparing a porous polymer scaffold,

II) forming a coating layer from the coating solution in which the coating agent is diluted with the diluent on the porous polymer scaffold, and

III) heat treating the coating layer at 70 to 150 ° C.

First, a porous polymer scaffold is prepared.

The porous polymer scaffold may be any one selected from the group consisting of polyvinylidene fluoride, polysulfone, polyacrylonitrile, polyimide, polyetherimide, and polyether sulfone.

Thereafter, II) a coating layer is formed from the coating solution diluted with the coating material for the carbon dioxide separation membrane on the porous polymer scaffold.

The solvent for diluting the coating agent is acetone, ethanol, methanol, hexane, water or the like in which the coating agent dissolves without dissolving the support.

The coating solution contains 0.5 to 20% by weight of the coating agent and 80 to 99.5% by weight of the diluent. When the concentration of the coating agent is less than 0.5% by weight, a coating layer functioning as a coating layer is uniformly formed If the concentration of the coating solution exceeds 20% by weight, the thickness of the coating layer becomes too thick, and gas permeability is remarkably reduced.

When the coating solution for the carbon dioxide separation membrane is diluted, the coating solution is impregnated into the polymer scaffold through the pores existing on the porous polymer scaffold. The porous coating scraped on the porous polymer scaffold, Respectively.

The diluent in step II) is diluted with at least one solvent selected from the group consisting of methanol, ethanol, acetone, hexane, water, acetonitrile, toluene, THF and chloroform.

The coating layer in step II) is formed by spin coating, dip coating, cast coating or spray coating.

Finally, the step III) is heat-treated at 70 to 150 ° C., preferably, the step III) is performed under the condition of an average relative humidity of 1 to 5%. In order to make such a condition, And a simple process of preheating the oven free from the outside to 70 to 150 ° C.

If the average relative humidity exceeds 5% during the heat treatment process, there is a problem that the urethane reaction is not sufficiently formed and the urea reaction is formed, which makes it difficult to judge the exact chemical structure. When the relative humidity is less than 1% Which is inefficient in terms of economy.

In the step (III), urethane and urea reaction are terminated by heat treatment by applying heat to the coating material coated on the surface of the porous polymer scaffold, and the urea and urea reaction are terminated. By the hydrogen bonding between the hard segments of the urethane bond or the urea bond, In the process for obtaining a solidified coating layer having a chemical bonding structure, when the heat treatment temperature range is lower than 70 ° C, there arises a problem that the heat treatment time required for forming a sufficient urethane bond is prolonged. When the temperature exceeds 150 ° C There is a problem that the economical efficiency is reduced and the porous polymer scaffold is exposed to high temperature for a long time to deteriorate.

The heat treatment in step III) may be carried out for 12 to 24 hours. Even if the reaction time is less than 12 hours, the urethane reaction may occur. However, the reaction should be completed for a sufficient time to avoid a complete reaction. The reaction temperature must be maintained, which is uneconomical and the productivity may be deteriorated.

By the heat treatment in the steps II) and III), a coating layer, in particular, a coating layer having a physicochemical crosslinking structure can be obtained.

Specifically, a coating layer having a crosslinked structure having a urethane bond, a urea bond and a physical crosslinking structure by entanglement with hydrogen bond can be obtained by the heat treatment in the step (III).

The composite membrane for carbon dioxide separation according to the present invention is formed while blocking the pores on the porous polymer scaffold, the permeability is not reduced, but the carbon dioxide permeability is 400 to 1000 GPU, preferably 700 to 1000 GPU, It can be confirmed that it is improved to 1000 GPU.

Hereinafter, the present invention will be described in more detail with reference to Examples and the like, but the scope and content of the present invention can not be construed to be limited or limited by the following Examples. It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the present invention as set forth in the following claims. It is natural that it belongs to the claims.

In addition, the experimental results presented below only show representative experimental results of the embodiments and the comparative examples, and the respective effects of various embodiments of the present invention which are not explicitly described below will be specifically described in the corresponding part.

( Manufacturing example Preparation of Coatings.

Polyethylene glycol-polydimethylsiloxane copolymer (IM22), tolylene-2,4-diisocyanate-terminated polypropylene glycol having m = 34 in the above formula (2), isophorone diisocyanate (diisocyanate chain extender) Tin dilaurate (urethane reaction catalyst) was mixed and stirred to obtain a coating agent.

At this time, the mixing molar ratio is shown in Table 1 below.

Content (mol) IM22 The tolylene-2,4-diisocyanate-terminated polypropylene glycol of formula (2) Chain extender Urethane reaction catalyst Production Example 1 One 0.16 4.05 0.36 Production Example 2 One 0.20 4.05 0.36 Production Example 3 One 0.31 4.05 0.36 Production Example 4 One 0.39 4.05 0.36 Production Example 5 One 0.47 4.05 0.36 Production Example 6 One 0.59 4.05 0.36

( Example  1-6) Preparation of coating film.

Each coating film was prepared using each of the coatings prepared according to Production Examples 1 to 6.

First, the coating agents of Preparation Examples 1 to 6 were mixed and stirred at room temperature for 1 hour, applied to a Teflon Petri dish, and allowed to stand at room temperature for 2 hours. Thereafter, For 24 hours at 80 캜 to prepare a coating film for separating carbon dioxide containing urethane structure and urea structure.

( Example  7-11) for carbon dioxide separation Composite membrane  Produce.

The coatings prepared in Preparation Examples 2 to 6 were diluted with acetone (diluent) to 8.5 wt%, respectively, and cast on the prepared porous polyacrylonitrile support to form a coating layer. Then, the coating layer was formed to have an average relative humidity of 1 to 5% And then heat-treated at 80 캜 for 24 hours to prepare a composite membrane for separating carbon dioxide including a coating layer having a urethane structure and a urea structure.

( Comparative Example  1 to 5) Preparation of coating film.

After mixing and stirring for 1 hour at room temperature, polyethylene glycol-polydimethylsiloxane copolymer (IM22), isophorone diisocyanate (diisocyanate chain extender) and dibutyltin dilaurate (urethane reaction catalyst) And allowed to stand at room temperature for 2 hours, and then heat-treated at 80 ° C for 24 hours under conditions of an average relative humidity of 1 to 5% to prepare a coating film for a carbon dioxide separation membrane containing a urethane structure and a urea structure.

The mixing molar ratio of the polyethylene glycol-polydimethylsiloxane copolymer (IM22), isophorone diisocyanate (diisocyanate chain extender) and dibutyltin dilaurate (urethane reaction catalyst) is shown in Table 2 below.

Content (mol) IM22 Diisocyanate chain extender Urethane reaction catalyst Comparative Example 1 One 3.24 0.36 Comparative Example 2 One 4.05 0.36 Comparative Example 3 One 4.86 0.36 Comparative Example 4 One 6.07 0.36 Comparative Example 5 One 8.10 0.36

( Comparative Example  6 to 8) Preparation of coating film.

Polyethylene glycol-polydimethylsiloxane copolymer (IM22), tolylene-2,4-diisocyanate-terminated polypropylene glycol having m = 34 in the above formula (2), isophorone diisocyanate (diisocyanate chain extender) A coating film was prepared in the same manner as in Comparative Example 1, except that the coating material described in [Table 3] was used as a mixed molar ratio of tin dilaurate (urethane reaction catalyst).

Content (mol) IM22 The tolylene-2,4-diisocyanate-terminated polypropylene glycol of formula (2) Diisocyanate chain extender Urethane reaction catalyst Comparative Example 6 1.5 0.20 4.05 0.36 Comparative Example 7 1.5 0.39 4.05 0.36 Comparative Example 8 1.5 0.20 8.10 0.36 Comparative Example 9 1.5 0.39 8.10 0.36

1 is a TGA thermal analysis graph of each of the coating films prepared in Examples 2 to 6 and the coating film prepared in Comparative Example 2. Fig.

1, the coating film prepared in Examples 2 to 6 and the coating film prepared in Comparative Example 2 had a primary decomposition temperature of 230 to 265 DEG C, a secondary decomposition temperature of 325 to 335 DEG C, Was confirmed to be superior due to chemical crosslinking due to increase of tolylene-2,4-diisocyanate-terminated polypropylene glycol and physical crosslinking by hydrogen bonding.

That is, as the content of tolylene-2,4-diisocyanate-terminated polypropylene glycol increases, the thermal stability is also improved. Particularly, the coating film of Example 6 has a primary decomposition temperature of 265 ° C and a secondary decomposition temperature of 335 ° C And the thermal stability was excellent.

2 is an IR analysis graph of the coating film prepared in Examples 2 to 6 and the coating film prepared in Comparative Example 2, respectively.

As shown in FIG. 2, the coating films prepared in Examples 2 to 6 and the coating films prepared in Comparative Example 2 were analyzed to find that the concentration of tolylene-2,4-diisocyanate-terminated polypropylene glycol increased , The C = O peak representing isocyanate, 1710 cm ^-1 , increased.

Further, CH ₂ peak and 2900cm ^- the CC bond peak at 1228cm ^{-1 1} was also increased.

As a result, the structure of the coating film formed to have urethane and urea reaction as well as physical crosslinking due to hydrogen bonding as the tolylene-2,4-diisocyanate-terminated polypropylene glycol increases is also C = O, CC, CH ₂ , Respectively.

That is, it can be seen that as the tolylene-2,4-diisocyanate-terminated polypropylene glycol increases, the physical crosslinking structure due to the hydrogen bonding between the chains of the coating film increases, thereby improving the thermal stability.

FIG. 3 is a graph showing tensile strength (stress (MPa)) according to strain rate for evaluating the mechanical properties of the coating film prepared in Examples 2 to 6 and the coating film prepared in Comparative Example 2. FIG.

As shown in FIG. 3, the tensile strength of the coating film prepared in Comparative Example 2 was twice or more than that of the coating films of Examples 2 to 6, but the elongation was as low as 100% or less, There was.

On the other hand, the coating films of Examples 2 to 6 had a tensile strength lower than that of Comparative Example 2 by a factor of 2 or more, but the elongation was more than 400% due to formation of a physical crosslinking structure due to hydrogen bonding and entanglement, Which is more than four times.

That is, when used as a single film for separating carbon dioxide or a composite film with a supporting layer, the coating or coating film used in Comparative Example 2 is easily broken, so that even if other properties are excellent, While it can not be put to practical use because it throws away,

The coatings or coating films used in Examples 2 to 6 had a relatively low tensile strength and belonged to the general values of 1.0 to 1.3 MPa and the elongation was four times or more higher than that of Comparative Example 1. Therefore, Can be fully utilized as a composite film of

Particularly, as compared with the case of using a single film as in the case of the coating films of Examples 2 to 6, the composite film with the supporting layer (Examples 7-11) is 10 times or more durable relatively.

In addition, since the composite membrane prepared using the coating agent used in Comparative Example 2 easily breaks down, the composite membrane of Examples 7 to 11 using the coating agents of Production Examples 2 to 6 is 10 times or more more durable than the composite membrane.

FIG. 4 is a graph showing permeability (Barrer) and oxygen / nitrogen selectivity (O ₂ / N ₂ selectivity) for oxygen and nitrogen of each of the coating films prepared in Comparative Examples 1 to 5.

FIG. 5 is a graph showing permeability (Barrer) and selectivity to carbon dioxide / nitrogen (CO ₂ / N ₂ selectivity) of each of the coating films prepared in Comparative Examples 1 to 5.

Table 4 shows the results of FIG. 4 and FIG. 5 as numerical values.

Barrer Selectivity N ₂ O ₂ CO ₂ O ₂ / N ₂ CO ₂ / N ₂ Comparative Example 1 14000 15300 17000 1.1 1.2 Comparative Example 2 54 115 890 2.1 16.4 Comparative Example 3 113 143 803 1.3 7.1 Comparative Example 4 5310 4710 5600 0.9 1.1 Comparative Example 5 72000 81000 87000 1.1 1.2

* Barrer (Gas Permeability Unit, 10-10 cm3 (STP) · cm / cm2 · sec · cmHg)

As shown in FIG. 4 and FIG. 5, it can be seen that the coating films prepared in Comparative Examples 1 to 5 have remarkably high transmittance but remarkably low selectivity of 10 or less.

However, in the case of the coating film of Comparative Example 2, the selectivity to carbon dioxide / nitrogen (CO ₂ / N ₂ selectivity) was 16.4 and had a selectivity of 10 or more.

Table 5 shows that when the coating film is prepared with the coating agent according to the present invention, when the components of the coating agent are excessively mixed, the amount of the coating film prepared in Comparative Examples 6 to 9 (O ₂ / N ₂ selectivity) for oxygen / nitrogen, carbon dioxide / nitrogen, and the like.

Barrer Selectivity N ₂ O ₂ CO ₂ O ₂ / N ₂ CO ₂ / N ₂ Comparative Example 6 920000 860000 630000 0.94 0.9 Comparative Example 7 800000 790000 750000 0.99 0.9 Comparative Example 8 146 130 415 0.89 2.84 Comparative Example 9 62 83 366 1.34 5.90

* Barrer (Gas Permeability Unit, 10 ^-10 × cm 3 (STP) · cm / cm 2 · sec · cm Hg)

As shown in Table 5, it was confirmed that when the IM22 was mixed excessively and when the IM22 and the diisocyanate chain extender were mixed in excess, the coating film was at least three times lower than the coating film prepared in Examples 2 to 6 according to the present invention .

FIG. 6 is a graph showing permeability (Barrer) and oxygen / nitrogen selectivity (O ₂ / N ₂ selectivity) for oxygen and nitrogen of each of the coating films prepared in Examples 1 to 6.

FIG. 7 is a graph showing the permeability (Barrer) and selectivity (CO ₂ / N ₂ selectivity) for carbon dioxide and nitrogen of each of the coating films prepared in Examples 1 to 6.

Table 6 shows the results of Figs. 6 and 7 as numerical values.

Barrer Selectivity N ₂ O ₂ CO ₂ O ₂ / N ₂ CO ₂ / N ₂ Example 1 51 100 807 2.0 15.8 Example 2 35 63 940 1.8 26.9 Example 3 21 31 806 1.5 38.8 Example 4 17 43 562 2.6 33.8 Example 5 16 43 485 2.6 30.2 Example 6 26 52 424 2.0 16.3

As shown in FIGS. 6 and 7, the coating films prepared from Examples 1 to 6 have a carbon dioxide / nitrogen selectivity of at least 15, and in particular, the coating films prepared from Examples 3 to 5 have carbon dioxide / And a carbon dioxide permeability of 400 to 810 barrer.

In addition, the coating films prepared from Examples 3 to 5 have a low selectivity to oxygen / nitrogen (O ₂ / N ₂ selectivity) of 1.5-2.6 and an oxygen permeability of 30-43, indicating excellent separation properties for carbon dioxide .

8 is a SEM photograph of the surface and cross section of the porous polyacrylonitrile support (a (surface, b; section) and the carbon dioxide-separated composite membrane prepared in Examples 7 to 11. FIG.

The surfaces of the composite membranes for separating carbon dioxide prepared in Examples 7 to 11 are in order c, e, g, i, k, and the cross sections are shown in order d, f, h, j,

According to the results, the coatings prepared in Production Examples 2 to 6 were coated on a support layer, and it was confirmed that the coating layer had a uniform structure without any defects on the surface and inside, and had no flat surface at all.

In addition, it was confirmed that the thicknesses of the coating layers in the composite membranes for separating carbon dioxide prepared in Examples 7 to 11 were 0.5 to 2.0 μm on average, and 1.4 to 1.8 μm, respectively.

9 is a graph showing permeability (GPU) and oxygen / nitrogen selectivity (O ₂ / N ₂ selectivity) for oxygen and nitrogen in each of the composite membranes for separating carbon dioxide prepared in Examples 7 to 11 .

10 is a graph showing the permeability (GPU) and selectivity (CO ₂ / N ₂ selectivity) for carbon dioxide and nitrogen of each of the composite membranes for separating carbon dioxide prepared in Examples 7 to 11 .

      Table 7 shows the results of Figs. 9 and 10 as numerical values.

Transmission (GPU) Selectivity N ₂ O ₂ CO ₂ O ₂ / N ₂ CO ₂ / N ₂ Example 7 51 125 940 2.5 18.4 Example 8 39 161 990 4.1 25.4 Example 9 26 86 760 3.4 29.5 Example 10 27 99 810 3.6 29.5 Example 11 31 92 710 3.0 23.1

As shown in FIGS. 9 and 10, the composite membranes for separating carbon dioxide prepared in Examples 7 to 11 exhibited a carbon dioxide / nitrogen selectivity of 15 or more, particularly in Examples 9 and 10, they were coated with a thin layer , It shows an excellent carbon dioxide / nitrogen selectivity close to 30.

That is, referring to Examples 9 to 10, the polyethylene glycol-polydimethylsiloxane copolymer represented by the formula (1), the tolylene-2,4-diisocyanate-terminated polyethylene glycol represented by the formula (2) The molar ratio of glycol and said diisocyanate chain extender is most preferably from 1: 0.39 to 0.47: 3.5 to 4.5, most preferably having a carbon dioxide / nitrogen selectivity in the range of from 25 to 35 close to 30, It can be confirmed that it has transparency.

As shown in Figs. 9 and 10, when the composite membranes for separating carbon dioxide of Examples 7 to 11 were produced, the coating solution used was The coating solution of the present invention is such that the concentration of the coating agent is 0.5 to 20% by weight and the concentration of the diluent is 80 to 99.5% by weight so that the concentration of the coating agent is 8.5% by weight and the concentration of the diluent is 91.5% It was confirmed that all of the diluted solutions had excellent selectivity.

However, considering both the selectivity of carbon dioxide to nitrogen and the permeation of carbon dioxide, it is most preferable that the coating solution contains 0.5 to 10% by weight of the coating agent and 90 to 99.5% by weight of the diluent.

Claims (10)

a) a polyethylene glycol-polydimethylsiloxane copolymer represented by the following formula (1);
&Lt; Formula 1 >

b) tolylene-2,4-diisocyanate-terminated polyethylene glycols or polypropylene glycols represented by the following formula (2);
(2)

c) a diisocyanate chain extender; And
d) a coating agent for a carbon dioxide separation membrane containing a urethane reaction catalyst
(Wherein n ₁ and n ₂ are an integer of 5 to 20, R ₁ is -CH ₂ CH ₂ O- or -CH ₂ CHCH ₃ O-, and m is an integer of 1 to 20). The method according to claim 1,
The diisocyanate chain extender may be any one selected from the group consisting of tolylene diisocyanate, isophorone diisocyanate, methylene diisocyanate, methylene diphenyl diisocyanate, hexamethylene diisocyanate, xylene diisocyanate and tolylidine diisocyanate Coating agent for a carbon dioxide separation membrane. The method according to claim 1,
The urethane reaction catalyst is selected from the group consisting of tin (II) acetate, tin (II) octoate, tin (II) ethylhexoate, tin (II) laurate, dibutyltin diacetate, dibutyltin dilaurate, (N, N-dimethylaminopropyl) -s-hexahydrotriazine, tetramethylammonium hydroxide, sodium hydroxide, sodium N - [(2-hydroxy- -Nonylphenyl) methyl] -N-methylaminoacetate, sodium acetate, sodium octoate, potassium acetate, potassium octoate, and mixtures thereof. The method according to claim 1,
A polyethylene glycol-polydimethylsiloxane copolymer represented by the formula (1), a tolylene-2,4-diisocyanate-terminated polyethylene glycol or polypropylene glycol represented by the formula 2, and a diisocyanate chain- Wherein the molar ratio is 1: 0.2-0.6: 3.3-8.0. A coating film for a carbon dioxide separation membrane produced by applying and heat-treating a coating material according to any one of claims 1 to 4. 6. The method of claim 5,
Wherein the coating film has a selectivity (CO 2 / N 2 selectivity) of carbon dioxide to nitrogen in air of 10 to 40 and a carbon dioxide permeability of 400 to 1000 Barrer. A porous polymeric support; And
A composite membrane for separating carbon dioxide, comprising a coating formed from the coating according to claim 1 on said porous polymeric support. 8. The method of claim 7,
Wherein the composite membrane has a selectivity (CO 2 / N 2 selectivity) of carbon dioxide to nitrogen in air of 10 to 40 and a permeability of carbon dioxide of 400 to 1000 GPU. I) preparing a porous polymer scaffold;
II) forming a coating layer on the porous polymer scaffold from a coating solution prepared by diluting the coating composition according to claim 1 with a diluent; And
III) heat treating the coating layer at 70 to 150 ° C. 10. The method of claim 9,
And the step (III) is carried out under conditions of an average relative humidity of 1 to 5%.

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