Film-forming composition, cured film, production method for cured film, production method for multilayer body, and co2 separation method

Abstract

To provide a film-forming composition capable of forming a film having a uniform film thickness; a cured film of the film-forming composition; a production method for the cured film; a production method for a multilayer body using the production method for the cured film; and a CO2 separation method using the multilayer body produced via the production method.SOLUTION: A film-forming composition includes polydimethylsiloxane, a curing agent, and at least one hydroxamic acid or related substance selected from among hydroxamic acids and salts thereof, and the content of the hydroxamic acid or related substance is greater than 0 mass% and less than 5 mass% relative to the mass of the polydimethylsiloxane.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a film-forming composition, a cured film, a method for producing a cured film, a method for producing a laminate, and a method for separating CO2. [Background technology]

[0002] In order to suppress global warming due to climate change and the like, technologies have been developed for separating and capturing carbon dioxide (CO2) using a CO2 separation membrane (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-15678 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the production of a CO2 separation membrane, for example, a membrane-forming composition containing polydimethylsiloxane (PDMS) is used. However, when the CO2 separation membrane is a thin film, using a membrane-forming composition containing polydimethylsiloxane, a liquid polymer, tends to cause unevenness in the membrane formed due to aggregation of polydimethylsiloxane, making it difficult to produce a CO2 separation membrane with a uniform thickness. In addition, not only in the case of CO2 separation membranes, but also in the case of other membranes produced using a membrane-forming composition containing polydimethylsiloxane, there is a problem in that the formed membrane is prone to have unevenness on its surface, making it difficult to produce a membrane with a uniform thickness.

[0005] The present invention has been made in consideration of the above-mentioned problems, and has an object to provide a film-forming composition that contains polydimethylsiloxane and is capable of forming a film with a uniform thickness, a cured film of the film-forming composition, a method for producing the cured film, a method for producing a laminate using the above-mentioned method for producing a cured film, and a CO2 separation method using a laminate produced by the production method. [Means for solving the problem]

[0006] The present inventors have found that the above-mentioned problems can be solved by a film-forming composition that contains polydimethylsiloxane, a curing agent, and at least one hydroxamic acid selected from hydroxamic acid and its salt, and the content of the hydroxamic acid is more than 0% by mass and less than 5% by mass relative to the mass of polydimethylsiloxane, and have thus completed the present invention. Specifically, the present invention provides the following.

[0007] [1] A composition comprising polydimethylsiloxane, a curing agent, and at least one hydroxamic acid selected from hydroxamic acid and its salts, The film-forming composition, wherein the content of the hydroxamic acids is more than 0 mass % and less than 5 mass % relative to the mass of the polydimethylsiloxane.

[0008] [2] The film forming composition according to [1] above, wherein the polydimethylsiloxane has a mass average molecular weight of 90,000 or more.

[0009] [3] The composition for forming a membrane according to [1] or [2] above, which is a composition for forming a CO2 separation membrane.

[0010] [4] A cured film comprising a cured product of the film-forming composition according to any one of [1] to [3] above, A cured film, wherein the content of the hydroxamic acids is more than 0 mass % and less than 5 mass % relative to the mass of the cured film.

[0011] [5] The cured film according to the above [4], having a surface roughness Ra of 10% or less of the film thickness of the cured film.

[0012] [6] The cured film according to the above [4] or [5], having a film thickness of 10 nm or more and 2000 nm or less.

[0013] [7] The cured film according to any one of the above [4] to [6], which is a CO2 separation membrane.

[0014] [8] A coating film forming step of forming a coating film of the film forming composition according to any one of the above [1] to [3]; A curing step of curing the coating film to form a cured film, A method for producing a cured film, wherein the content of the hydroxamic acids in the cured film is adjusted to more than 0 mass% and less than 5 mass% in the curing step.

[0015] [9] The method for producing a cured film according to the above [8], wherein the cured film is a CO2 separation membrane.

[0016]

[10] A method for producing a laminate in which a CO2 separation membrane and a supporting substrate are laminated, comprising the steps of: 10. A method for producing a laminate, comprising a CO2 separation membrane production step, comprising producing the CO2 separation membrane by the method for producing a cured membrane according to claim 9.

[0017]

[11] A laminate production step of producing a laminate by the laminate production method according to

[10] above; A CO2 separation method comprising a separation step of supplying a gas containing CO2 to the laminate and separating CO2 from the gas. Effect of the Invention

[0018] According to the present invention, there are provided a film-forming composition which contains polydimethylsiloxane and is capable of forming a film with a uniform thickness, a cured film of the film-forming composition, a method for producing the cured film, a method for producing a laminate using the above-mentioned method for producing a cured film, and a CO2 separation method using a laminate produced by the production method. [Brief description of the drawings]

[0019] [Figure 1] 1A to 1C are schematic diagrams illustrating a method for producing a laminate. [Diagram 2] 4 is a photograph showing the observation results of Comparative Example 1. [Diagram 3] 4 is a photograph showing the observation results of Comparative Example 2. [Figure 4] 4 is a photograph showing the observation results of Comparative Example 3. [Diagram 5] 3 is a photograph showing the observation results of Example 1. [Figure 6] 1 is a graph showing the measurement results of film thickness and surface roughness Ra in Examples 2 to 4. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] ≪Film-forming composition≫ The film-forming composition contains polydimethylsiloxane, a curing agent, and at least one hydroxamic acid selected from hydroxamic acid and its salts. In the film forming composition, the content of hydroxamic acids is more than 0 mass % and less than 5 mass % based on the mass of polydimethylsiloxane.

[0021] By using the above-mentioned film-forming composition, a film with a more uniform thickness can be formed than when a film-forming composition having a hydroxamic acid content outside the above range is used, as shown in the examples described below. The reason why a film having a uniform thickness can be formed by using the above-mentioned film-forming composition is unclear, but is presumed to be due to the following reasons. When the film-forming composition contains a small amount (more than 0% by mass and less than 5% by mass) of benzhydroxamic acids, the polydimethylsiloxane in the film-forming composition is made to have a high molecular weight when forming a film (cured film). This suppresses the aggregation of polydimethylsiloxane, making the film less likely to have unevenness (for example, a smooth film), and a film with a uniform thickness can be obtained. Since the membrane has a uniform thickness, when the formed membrane is used as a separation membrane such as a CO2 separation membrane, the separation performance can be made uniform throughout the entire membrane.

[0022] On the other hand, if the film-forming composition does not contain even a small amount (more than 0% by mass and less than 5% by mass) of benzhydroxamic acids, the polydimethylsiloxane tends to aggregate, resulting in unevenness in the film formed, making it difficult to obtain a film with a uniform thickness.

[0023] When the film to be formed is a thin film, if a film-forming composition containing polydimethylsiloxane, which is a liquid polymer, is used, the polydimethylsiloxane aggregates, which tends to cause unevenness in the film to be formed, making it difficult to produce a film with a uniform thickness. However, by using the above-mentioned film-forming composition, it is possible to make the film thickness uniform even if it is a thin film (for example, 10 nm or more and 2000 nm or less).

[0024] In the film-forming composition, the content of hydroxamic acids may be more than 0% by mass and less than 5% by mass relative to the mass of polydimethylsiloxane, but is preferably 0.05% by mass or more and 4% by mass or less, and more preferably 1% by mass or more and 3% by mass or less. That is, in the film-forming composition, (mass of hydroxamic acids) / (mass of polydimethylsiloxane)×100 may be more than 0 and less than 5, but is preferably 0.05 to 4, and more preferably 1 to 3.

[0025] The hydroxamic acid contained in the film-forming composition is at least one selected from hydroxamic acid and a salt thereof. Hydroxamic acids include benzhydroxamic acid (N-hydroxybenzamide), 1-naphthohydroxamic acid, and salicylhydroxamic acid. Hydroxamic acid salts include sodium salts of hydroxamic acids, such as sodium benzohydroxamate.

[0026] The polydimethylsiloxane contained in the film forming composition may have hydroxyl groups at both ends or one end of the molecular chain. The polydimethylsiloxane contained in the film-forming composition may be an elastomer.

[0027] The mass average molecular weight Mw of the polydimethylsiloxane contained in the film forming composition is preferably 90,000 or more, more preferably 95,000 or more, and even more preferably 100,000 or more. The polydispersity of polydimethylsiloxane (weight average molecular weight Mw / number average molecular weight Mn) is preferably 1 or more and 20 or less, more preferably 3 or more and 15 or less, and even more preferably 5 or more and 10 or less. In this specification, the mass average molecular weight Mw and the number average molecular weight Mn can be defined as relative values ​​calculated in terms of polystyrene in GPC (gel permeation chromatography) measurement. The content of polydimethylsiloxane in the film-forming composition is not particularly limited. The content of polydimethylsiloxane in the film-forming composition is preferably 1% by mass or more and 20% by mass or less, more preferably 3% by mass or more and 18% by mass or less, and even more preferably 5% by mass or more and 15% by mass or less.

[0028] The curing agent contained in the film-forming composition is a curing agent that cures polydimethylsiloxane. Examples of the curing agent include alkoxysilanes such as tetramethoxysilane, trimethoxymethylsilane, dimethoxydimethylsilane, methoxytrimethylsilane, and γ-glycidoxypropyltrimethoxysilane.

[0029] The content of the curing agent in the film-forming composition is not particularly limited. In the film-forming composition, the content of the curing agent is preferably 0.1 parts by mass or more and 20 parts by mass or less, more preferably 1 part by mass or more and 10 parts by mass or less, based on 100 parts by mass of polydimethylsiloxane.

[0030] The film-forming composition may contain a solvent. The boiling point of the solvent is not particularly limited, but is preferably from 70°C to 300°C, more preferably from 80°C to 250°C, and even more preferably from 90°C to 200°C.

[0031] Examples of the solvent contained in the film-forming composition include sulfoxides, sulfones, amides, lactams, imidazolidinones, dialkyl glycol ethers, (poly)alkylene glycol monoalkyl ethers, (poly)alkylene glycol monoalkyl ether acetates, other ethers, ketones, other esters, lactones, linear, branched, or cyclic aliphatic hydrocarbons, aromatic hydrocarbons, and terpenes. The sulfoxides include dimethyl sulfoxide. Examples of sulfones include dimethyl sulfone, diethyl sulfone, bis(2-hydroxyethyl) sulfone, and tetramethylene sulfone. Examples of amides include N,N-dimethylformamide, N-methylformamide, N,N-dimethylacetamide, N-methylacetamide, and N,N-diethylacetamide. Examples of lactams include N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N-propyl-2-pyrrolidone, N-hydroxymethyl-2-pyrrolidone, and N-hydroxyethyl-2-pyrrolidone. Examples of imidazolidinones include 1,3-dimethyl-2-imidazolidinone, 1,3-diethyl-2-imidazolidinone, and 1,3-diisopropyl-2-imidazolidinone. Examples of dialkyl glycol ethers include dimethyl glycol, dimethyl diglycol, dimethyl triglycol, methyl ethyl diglycol, diethyl glycol, and triethylene glycol butyl methyl ether. Examples of (poly)alkylene glycol monoalkyl ethers include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol mono-n-propyl ether, ethylene glycol mono-n-butyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol mono-n-propyl ether, diethylene glycol mono-n-butyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol mono-n-propyl ether, propylene glycol mono-n-butyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol mono-n-propyl ether, dipropylene glycol mono-n-butyl ether, tripropylene glycol monomethyl ether, and tripropylene glycol monoethyl ether. Examples of the (poly)alkylene glycol monoalkyl ether acetates include ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether acetate, and propylene glycol monoethyl ether acetate. Examples of other ethers include dimethyl ether, diethyl ether, methyl ethyl ether, dipropyl ether, diisopropyl ether, dibutyl ether, diisoamyl ether, diethylene glycol dimethyl ether, diethylene glycol methyl ethyl ether, diethylene glycol monobutyl ether, diethylene glycol diethyl ether, tetraethylene glycol dimethyl ether, and tetrahydrofuran. Examples of ketones include methyl ethyl ketone, cyclohexanone, 2-heptanone, 3-heptanone, and 2,6-dimethyl-4-heptanone. Other esters include, for example, alkyl lactate esters such as methyl lactate and ethyl lactate; ethyl 2-hydroxy-2-methylpropionate, methyl 3-methoxypropionate, ethyl 3-methoxypropionate, methyl 3-ethoxypropionate, ethyl 3-ethoxypropionate, ethyl ethoxyacetate, ethyl hydroxyacetate, methyl 2-hydroxy-3-methylbutanoate, 3-methoxybutyl acetate, 3-methyl-3-methoxy-1-butyl acetate, 3-methyl-3-methoxybutylpropionate, ethyl acetate, and acetic acid. Examples of the ethyl acetate include n-propyl, isopropyl acetate, n-butyl acetate, isobutyl acetate, n-pentyl acetate, n-hexyl acetate, n-heptyl acetate, n-octyl acetate, n-pentyl formate, isopentyl acetate, n-butyl propionate, ethyl butyrate, n-propyl butyrate, isopropyl butyrate, butyl butyrate, methyl n-octanoate, methyl decanoate, methyl pyruvate, ethyl pyruvate, n-propyl pyruvate, methyl acetoacetate, ethyl acetoacetate, ethyl 2-oxobutanoate, dimethyl adipate, and propylene glycol diacetate. Examples of lactones include propylolactone, γ-butyrolactone, and 6-pentyrolactone. Examples of linear, branched, or cyclic aliphatic hydrocarbons include n-hexane, n-heptane, n-octane, n-nonane, methyloctane, n-decane, n-pentane, n-dodecane, 2,2,4,6,6-pentamethylheptane, 2,2,4,4,6,8,8-heptamethylnonane, cyclohexane, and methylcyclohexane. Examples of aromatic hydrocarbons include benzene, toluene, benzotrifluoride, xylene, 1,3,5-trimethylbenzene, naphthalene, and decahydronaphthalene. Examples of terpenes include p-menthane, diphenylmenthane, limonene, terpinene, bornane, norbornane, and pinane.

[0032] The method for preparing the film-forming composition is not particularly limited. The film-forming composition is typically prepared by uniformly mixing polydimethylsiloxane, a curing agent, a hydroxamic acid, a solvent, and other components that are optionally contained.

[0033] ≪Cured film≫ The cured film is made of the cured product of the film-forming composition described above. The cured film has a content of hydroxamic acids of more than 0 mass % and less than 5 mass % based on the mass of the cured film. Thus, the cured film contains a cured product in which polydimethylsiloxane is cured with a curing agent, and hydroxamic acids, and the content of the hydroxamic acids is more than 0 mass % and less than 5 mass % with respect to the mass of the cured film.

[0034] As shown in the examples described later, such a cured film has a more uniform thickness than a cured film having a hydroxamic acid content outside the above range. For example, the surface roughness Ra of the cured film is 10% or less of the film thickness of the cured film. The surface roughness Ra is a value defined by JIS B 0601 (1994).

[0035] In the cured film, the content of hydroxamic acids may be more than 0% by mass and less than 5% by mass, preferably from 0.01% to 4% by mass, and more preferably from 1% to 2% by mass, based on the mass of the cured film.

[0036] The thickness of the cured film is not limited. The cured film may be a thin film having a thickness of, for example, 10 nm to 2000 nm. The thickness of the cured film may be 1000 nm or less, 500 nm or less, or 200 nm or less.

[0037] The size of the cured film is not limited. For example, the cured film has an area of ​​0.03 m 2 or more (e.g., 0.03 m 2 More than 1000m 2 A large membrane having a diameter of 100 mm or less may also be used.

[0038] Since the cured membrane has a uniform thickness, when the cured membrane is used as a separation membrane such as a CO2 separation membrane, the separation membrane exhibits uniform separation performance throughout the entire membrane.

[0039] <Production method of cured film> The above-mentioned cured film can be produced, for example, by a method for producing a cured film, which includes a coating film forming step of forming a coating film of the above-mentioned film-forming composition, and a curing step of curing the coating film to form a cured film. In the method for producing the cured film, the content of hydroxamic acids in the cured film is adjusted to more than 0% by mass and less than 5% by mass in the curing step. Each step is described below.

[0040] [Coating film formation process] In the coating film forming step, a coating film of the above-mentioned film forming composition is formed. The method for forming the coating film is not particularly limited, and examples thereof include a method for coating the above-mentioned film-forming composition by a bar coating method, a slit die coating method, a gravure coating method, a spin coating method, a spray method, a roller coating method, a dipping method, etc. When a large film is formed, a gravure coating method such as microgravure coating using a gravure roll is preferred.

[0041] [Curing process] In the curing step, the coating film is cured to form a cured film. In the curing step, the content of hydroxamic acids in the cured film is adjusted to be more than 0% by mass and less than 5% by mass.

[0042] An example of a method for curing the coating film is heating the coating film. The heating (drying) temperature of the coating film is, for example, 50°C or more and 160°C or less, preferably 80°C or more and 150°C or less, and more preferably 110°C or more and 140°C or less. The heating (drying) time for the coating film is, for example, from 5 minutes to 120 minutes, preferably from 10 minutes to 60 minutes, and more preferably from 15 minutes to 30 minutes.

[0043] Since the film-forming composition contains hydroxamic acids, a solvent, etc., the coating film also contains hydroxamic acids, a solvent, etc. During the curing step, the hydroxamic acids, the solvent, etc. may decompose or volatilize, and the content ratio of the hydroxamic acids may change. On the other hand, the cured film formed by the above-mentioned method for producing a cured film has a content of hydroxamic acids of more than 0% by mass and less than 5% by mass relative to the mass of the cured film. Therefore, in the curing step, the content of hydroxamic acids in the cured film is adjusted to be more than 0% by mass and less than 5% by mass. The content of the hydroxamic acids in the cured film can be adjusted by, for example, the heating temperature or heating time.

[0044] The cured membrane produced by such a production method has a uniform thickness, and therefore when used as a separation membrane such as a CO2 separation membrane, the separation performance can be made uniform throughout the entire membrane.

[0045] <<Method for manufacturing laminate>> The method for producing a laminate is a method for producing a laminate in which a CO2 separation membrane and a supporting substrate are laminated together. The method for producing the laminate includes a CO2 separation membrane production step of producing a CO2 separation membrane by the above-mentioned method for producing a cured membrane. A method for producing a laminate, for example, when the supporting substrate is a porous body, includes the steps of: A sacrificial layer forming step of forming a sacrificial layer on a support using a sacrificial layer forming composition; a CO2 separation membrane production process for producing a CO2 separation membrane on the sacrificial layer by the above-mentioned method for producing a cured membrane; a bonding step of bonding a support substrate onto the CO2 separation membrane; a peeling step of peeling off the support after the adhesion step; It is preferable to have a sacrificial layer removing step of removing the sacrificial layer by dissolving the sacrificial layer in a liquid after the peeling step. Each step will be described below with reference to Fig. 1. Fig. 1 is a schematic diagram illustrating the method for producing a laminate.

[0046] [Sacrificial layer formation process] In the sacrificial layer forming step, a sacrificial layer 2 is formed on a support 1 using a composition for forming a sacrificial layer (FIG. 1(a)). The composition for forming a sacrificial layer is not particularly limited as long as it is a composition that can form a sacrificial layer that can be removed in a subsequent sacrificial layer removal step. The composition for forming a sacrificial layer typically contains a resin and a solvent.

[0047] Examples of resins contained in the composition for forming the sacrificial layer include polyvinyl alcohol resin, dextrin, gelatin, glue, casein, shellac, gum arabic, starch, protein, polyacrylic acid amide, sodium polyacrylate, polyvinyl methyl ether, a copolymer of methyl vinyl ether and maleic anhydride, a copolymer of vinyl acetate and itaconic acid, polyvinylpyrrolidone, acetyl cellulose, acetyl butyl cellulose, carboxymethyl cellulose, methyl cellulose, hydroxyethyl cellulose, sodium alginate, and the like.

[0048] The amount of the resin contained in the composition for forming a sacrificial layer is not particularly limited as long as it does not impair the object of the present invention, and is appropriately determined in consideration of the coating property of the composition for forming a sacrificial layer, etc. Typically, the amount of the resin in the composition for forming a sacrificial layer is preferably an amount in which the relationship between the amount of the resin in the composition for forming a sacrificial layer and the amount of the solvent described later satisfies the following relationship. When the mass of the resin in the composition for forming a sacrificial layer is 100 parts by mass, the amount of the solvent is preferably 100 parts by mass or more and 10,000 parts by mass or less, more preferably 500 parts by mass or more and 8,000 parts by mass or less, and particularly preferably 700 parts by mass or more and 6,000 parts by mass or less.

[0049] The solvent contained in the composition for forming a sacrificial layer is not particularly limited as long as the resin is soluble in the solvent. As long as a predetermined amount of the resin is dissolved in the composition for forming a sacrificial layer, the composition for forming a sacrificial layer may contain the resin in an undissolved state. It is preferable that the resin is completely dissolved in the composition for forming a sacrificial layer.

[0050] The solvent may be water, an organic solvent, or an aqueous solution of an organic solvent.

[0051] Specific examples of organic solvents used as the solvent include: Methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, sec-butanol, tert-butanol, n-pentanol, isopentanol, 2-methylbutanol, sec-pentanol, tert-pentanol, 3-methoxybutanol, 3-methyl-3-methoxybutanol, n-hexanol, 2-methylpentanol, sec-hexanol, 2-ethyl-1-butanol, sec-heptanol, 3-heptanol, 1-octanol, 2-ethylhexanol monoalcohol solvents such as hexane, sec-octanol, n-nonyl alcohol, 2,6-dimethyl-4-heptanol, n-decanol, sec-pentadecyl alcohol, trimethylnonyl alcohol, sec-tetradecyl alcohol, sec-heptadecyl alcohol, methyl isobutyl carbinol, phenol, cyclohexanol, methylcyclohexanol, 3,3,5-trimethylcyclohexanol, benzyl alcohol, phenylmethylcarbinol, diacetone alcohol, and cresol; Sulfoxides such as dimethyl sulfoxide; Sulfones such as dimethyl sulfone, diethyl sulfone, bis(2-hydroxyethyl) sulfone, and tetramethylene sulfone; Amides such as N,N-dimethylformamide, N-methylformamide, N,N-dimethylacetamide, N-methylacetamide, and N,N-diethylacetamide; Lactams such as N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N-propyl-2-pyrrolidone, N-hydroxymethyl-2-pyrrolidone, and N-hydroxyethyl-2-pyrrolidone; Imidazolidinones such as 1,3-dimethyl-2-imidazolidinone, 1,3-diethyl-2-imidazolidinone, and 1,3-diisopropyl-2-imidazolidinone; dialkyl glycol ethers such as dimethyl glycol, dimethyl diglycol, dimethyl triglycol, methyl ethyl diglycol, diethyl glycol, and triethylene glycol butyl methyl ether; (poly)alkylene glycol monoalkyl ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol mono-n-propyl ether, ethylene glycol mono-n-butyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol mono-n-propyl ether, diethylene glycol mono-n-butyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol mono-n-propyl ether, propylene glycol mono-n-butyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol mono-n-propyl ether, dipropylene glycol mono-n-butyl ether, tripropylene glycol monomethyl ether, and tripropylene glycol monoethyl ether; (poly)alkylene glycol monoalkyl ether acetates such as ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether acetate, and propylene glycol monoethyl ether acetate; Other ethers such as dimethyl ether, diethyl ether, methyl ethyl ether, dipropyl ether, diisopropyl ether, dibutyl ether, diisoamyl ether, diethylene glycol dimethyl ether, diethylene glycol methyl ethyl ether, diethylene glycol diethyl ether, tetrahydrofuran, etc.; Ketones such as methyl ethyl ketone, cyclohexanone, 2-heptanone, and 3-heptanone; Lactic acid alkyl esters such as methyl 2-hydroxypropionate and ethyl 2-hydroxypropionate; other esters such as ethyl 2-hydroxy-2-methylpropionate, methyl 3-methoxypropionate, ethyl 3-methoxypropionate, methyl 3-ethoxypropionate, ethyl 3-ethoxypropionate, ethyl ethoxyacetate, ethyl hydroxyacetate, methyl 2-hydroxy-3-methylbutanoate, 3-methyl-3-methoxybutyl acetate, 3-methyl-3-methoxybutylpropionate, ethyl acetate, n-propyl acetate, i-propyl acetate, n-butyl acetate, i-butyl acetate, n-pentyl formate, i-pentyl acetate, n-butyl propionate, ethyl butyrate, n-propyl butyrate, i-propyl butyrate, n-butyl butyrate, methyl pyruvate, ethyl pyruvate, n-propyl pyruvate, methyl acetoacetate, ethyl acetoacetate, and ethyl 2-oxobutanoate; Lactones such as β-propylolactone, γ-butyrolactone, and δ-pentyrolactone; Linear, branched, or cyclic aliphatic hydrocarbons, such as n-hexane, n-heptane, n-octane, n-nonane, methyloctane, n-decane, n-undecane, n-dodecane, 2,2,4,6,6-pentamethylheptane, 2,2,4,4,6,8,8-heptamethylnonane, cyclohexane, and methylcyclohexane; Aromatic hydrocarbons such as benzene, toluene, xylene, 1,3,5-trimethylbenzene, and naphthalene; Terpenes such as p-menthane, diphenylmenthane, limonene, terpinene, bornane, norbornane, and pinane;

[0052] When the solvent is a mixed solvent of water and an organic solvent, the content of the organic solvent in the solvent is preferably 10% by mass or more, and more preferably 20% by mass or more.

[0053] The composition for forming a sacrificial layer may contain various components other than the resin and the solvent, as long as the purpose of the present invention is not impaired. Examples of the other components include a viscosity modifier, a surfactant, and a defoaming agent.

[0054] The method for preparing the composition for forming a sacrificial layer is not particularly limited. The composition for forming a sacrificial layer is typically prepared by uniformly mixing predetermined amounts of a resin, a solvent, and other components to be contained as necessary.

[0055] Examples of the support 1 on which the sacrificial layer 2 is formed using such a sacrificial layer-forming composition include resin films such as PET (polyethylene terephthalate) films, and substrates such as silicon substrates and glass substrates. In the support 1, the surface on which the sacrificial layer 2 is formed may or may not be treated with a release agent. The shape of the support 1 is not particularly limited, and may be a film or a plate. When the support is in the form of a film, a film pulled out from a film roll can be used as the support 1.

[0056] The method for forming the sacrificial layer 2 on the support 1 using a composition for forming a sacrificial layer is not particularly limited, and examples of the method include coating methods such as bar coating, slit die coating, gravure coating, spin coating, spraying, roller coating, and dipping.

[0057] After the composition for forming a sacrificial layer is applied to the support 1, the applied film of the composition for forming a sacrificial layer may be heated (dried) as necessary to remove at least a portion of the solvent of the composition for forming a sacrificial layer. The heating temperature of the coating film of the composition for forming a sacrificial layer is, for example, 50° C. or more and 90° C. or less. In addition, the coating film may be heated at a low temperature (for example, 50° C. or more and less than 70° C.) and then heated at a high temperature (for example, 70° C. or more and 90° C. or less).

[0058] The film thickness of the sacrificial layer 2 is not particularly limited, but is preferably from 1 μm to 20 μm, more preferably from 3 μm to 18 μm, and further preferably from 5 μm to 15 μm.

[0059] [CO2 separation membrane manufacturing process] In the CO2 separation membrane manufacturing process, a CO2 separation membrane 3 is formed on the sacrificial layer 2 by the above-mentioned method for manufacturing a cured membrane (FIG. 1(b)).

[0060] [Adhesion process] In the bonding step, a support substrate 4 is bonded onto the CO2 separation membrane 3 (FIG. 1(c)). When the CO2 separation membrane 3 is, for example, a thin or large membrane, it is difficult for the CO2 separation membrane 3 to stand on its own, and deformation or breakage is likely to occur. By adhering a support substrate 4 that supports (reinforces) the CO2 separation membrane 3 to the CO2 separation membrane 3, deformation and breakage can be suppressed, and functions such as the separation performance of the CO2 separation membrane 3 can be maintained.

[0061] The material of the support substrate 4 may be an organic material or an inorganic material, but is preferably an organic material, which is typically a resin. Examples of the resin include polyacetal, polyamide, polycarbonate, polyester (polybutylene terephthalate, polyethylene terephthalate, polyarylate, etc.), FR-AS resin, FR-ABS resin, AS resin, ABS resin, polyphenylene oxide, polyphenylene sulfide, polysulfone, polyethersulfone, polyetheretherketone, fluorine-based resin (polytetrafluoroethylene, polyvinylidene fluoride, etc.), polyimide, polyamideimide, polyamide bismaleimide, polyetherimide, polybenzoxazole, polybenzothiazole, polybenzimidazole, silicone resin, BT resin, polymethylpentene, ultra-high molecular weight polyethylene, FR-polypropylene, (meth)acrylic resin (polymethyl methacrylate, etc.), and polystyrene. Among resins, polyvinylidene fluoride, polyethersulfone, polyimide, and polyamideimide are preferred because they are thermally and chemically stable and can easily produce membranes with excellent mechanical strength. Do is preferred. As the material for the film, a mixture of two or more resins may be used. The supporting substrate 4 is preferably a porous body that is gas permeable. The shape of the supporting substrate 4 is not particularly limited, and may be a film or a plate. When the supporting substrate is in the form of a film, a film pulled out from a film roll can be used as the supporting substrate 4.

[0062] The thickness of the supporting substrate 4 is not particularly limited, but is preferably from 1 μm to 100 μm, more preferably from 10 μm to 80 μm, and even more preferably from 20 μm to 60 μm.

[0063] There is no particular limitation on the method for adhering the support substrate 4 onto the CO2 separation membrane 3. For example, lamination or a transfer method utilizing intermolecular forces may be used. For example, the CO2 separation membrane 3 may be laminated (thermocompression bonded) to the support substrate 4 using a roll 11 or the like at a pressure that does not damage the support substrate 4. The conditions for thermocompression bonding are a roller pressure of 0.1 kgf / cm 2 More than 10kgf / cm 2 Less than 0.2kgf / cm is preferable. 2 More than 5kgf / cm 2 The temperature of the roller is preferably 20° C. or higher and 120° C. or lower, and more preferably 25° C. or higher and 100° C. or lower. When using intermolecular forces, the CO2 separation membrane 3 and the support substrate 4 may be brought into contact with each other using, for example, a roller.

[0064] [Peeling process] In the peeling step, after the bonding step, the support 1 is peeled off (FIG. 1(d)). The method for peeling the support 1 from the sacrificial layer 2 is not particularly limited. Examples include a method in which the support 1 is peeled off from the sacrificial layer 2 without using a peeling liquid or the like. For example, when the support 1 is in the form of a film, the support 1 can be peeled off from the sacrificial layer 2 by unwinding the film. When the support 1 is peeled off from the sacrificial layer 2, a part of the sacrificial layer 2 may be peeled off together with the support 1.

[0065] [Sacrificial layer removal process] In the sacrificial layer removal process, after the peeling process, the sacrificial layer 2 is removed by dissolving it in a liquid (Figure 1(e)). This allows the production of a laminate 10 in which a CO2 separation membrane 3 and a support substrate 4 are laminated (Figure 1(f)). The laminate 10 may be dried using an air flow, a dryer, or the like, if necessary.

[0066] The liquid for dissolving the sacrificial layer 2 may be water, an organic solvent, or a mixed solvent of water and an organic solvent. When dissolving the sacrificial layer with these liquids, a part of the sacrificial layer may remain without being dissolved in the liquid. In order to remove the remaining sacrificial layer, it is preferable to further dissolve the sacrificial layer using, for example, an alkaline aqueous solution (basic aqueous solution).

[0067] The method for dissolving the sacrificial layer 2 in liquid is not particularly limited, but examples include washing the sacrificial layer 2 with running water, immersing the sacrificial layer 2 in liquid, or spraying the sacrificial layer 2 with liquid from a shower.

[0068] ≪CO2 separation method≫ The CO2 separation method includes a laminate manufacturing process for manufacturing a laminate in which a CO2 separation membrane and a support substrate are stacked by the above-mentioned laminate manufacturing method, and a separation process for separating CO2 from the gas by supplying a gas containing CO2 to the laminate. By using such a CO2 separation method, it is possible to prevent global warming caused by CO2 by separating and capturing the CO2. In addition, the captured CO2 can be used as a carbon resource. EXAMPLES

[0069] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0070] Example 1 <Preparation of film-forming composition> A film-forming composition was prepared by dissolving 88.5 parts by mass of PDMS elastomer having a hydroxyl group at the end (mass average molecular weight Mn=106400, dispersity Mw / Mn=6.29), 8.9 parts by mass of trimethoxymethylsilane, and 2.6 parts by mass of benzhydroxamic acid in a solvent so that the PDMS elastomer concentration was 5% by mass. Note that heptane (boiling point 98°C), butyl acetate (boiling point 126°C), and decahydronaphthalene (boiling point 185°C) were used as the solvent, and a film-forming composition was prepared with each solvent.

[0071] <Manufacture of hardened membranes (CO2 separation membranes)> First, 10 μL of a 10% by mass ethanol solution of polyvinyl alcohol was dropped onto a support (PET film) as a sacrificial layer forming composition. The sacrificial layer forming composition dropped onto the support 1 was applied onto the support 1 by a bar coating method to form a sacrificial layer with a thickness of 15 μm (sacrificial layer forming step).

[0072] Next, the film-forming composition was applied in the form of a layer on the sacrificial layer by a bar coating method, and heated on a hot plate at 120° C. for 20 minutes to form a cured film (CO 2 separation film) with a thickness of 1000 nm (film formation step).

[0073] Comparative Example 1 The same procedure as in Example 1 was carried out, except that a film-forming composition was prepared by the following method instead of the above <Preparation of film-forming composition>. A film-forming composition was prepared by dissolving SYLGARD (registered trademark) 184 (Dow Corning Corporation, polydimethylsiloxane (mass average molecular weight Mn = 19,500, dispersity Mw / Mn = 4.14), PDMS:curing agent = 10:1) in a solvent to a PDMS concentration of 5 mass %. Note that heptane (boiling point 98°C), butyl acetate (boiling point 126°C), and decahydronaphthalene (boiling point 185°C) were used as the solvent, and a film-forming composition was prepared with each solvent.

[0074] Comparative Example 2 The same operations as in Example 1 were carried out, except that in the above <Preparation of film-forming composition>, 88.5 parts by mass of PDMS elastomer having hydroxyl groups at its terminals (mass average molecular weight Mn = 106,400, dispersity Mw / Mn = 6.29), 8.9 parts by mass of trimethoxymethylsilane, and 2.6 parts by mass of benzhydroxamic acid were replaced with 90 parts by mass of PDMS elastomer having hydroxyl groups at its terminals (mass average molecular weight Mn = 52,700, Mw / Mn = 2.82) and 10 parts by mass of trimethoxymethylsilane.

[0075] Comparative Example 3 The same operations as in Example 1 were carried out, except that in the above <Preparation of film-forming composition>, 88.5 parts by mass of PDMS elastomer having hydroxyl groups at its terminals (mass average molecular weight Mn = 106,400, dispersity Mw / Mn = 6.29), 8.9 parts by mass of trimethoxymethylsilane, and 2.6 parts by mass of benzhydroxamic acid were replaced with 90 parts by mass of PDMS elastomer having hydroxyl groups at its terminals (mass average molecular weight Mn = 86,900, Mw / Mn = 3.73) and 10 parts by mass of trimethoxymethylsilane.

[0076] <Observation of film surface> The surface of the obtained cured film was observed with a digital microscope. Photographs at a magnification of 20 times are shown in Figs. 2 to 5. Fig. 2 is a photograph showing the observation result of Comparative Example 1, Fig. 3 is a photograph showing the observation result of Comparative Example 2, Fig. 4 is a photograph showing the observation result of Comparative Example 3, and Fig. 5 is a photograph showing the observation result of Example 1. Figs. 2(a), 3(a), 4(a), and 5(a) are the observation results when a film-forming composition in which the solvent is heptane is used. Figs. 2(b), 3(b), 4(b), and 5(b) are the observation results when a film-forming composition in which the solvent is butyl acetate is used. Figs. 2(c), 3(c), 4(c), and 5(c) are the observation results when a film-forming composition in which the solvent is decahydronaphthalene is used.

[0077] As shown in FIG. 5, in Example 1, which used a film-forming composition containing polydimethylsiloxane, a curing agent, and hydroxamic acids, where the content of hydroxamic acids was more than 0 mass % and less than 5 mass % relative to the mass of polydimethylsiloxane, PDMS did not aggregate, no irregularities were observed on the film surface, the film thickness had extremely small variation, and the film thickness was uniform. In contrast, as shown in FIGS. 2 to 4, in Comparative Examples 1 to 3 in which a film-forming composition not containing hydroxamic acids was used, PDMS aggregated into droplets, and the film thickness varied more than in Example 1.

[0078] <Measurement of benzhydroxamic acid content in membrane> The content of benzhydroxamic acid in the obtained cured film was measured by liquid chromatography. As a result, the content of benzhydroxamic acid in the cured film of Example 1 was 1.8 mass% relative to the mass of the cured film. On the other hand, the cured films of Comparative Examples 1 to 3 did not contain benzhydroxamic acid.

[0079] [Examples 2 to 4] The film-forming composition prepared in <Preparation of film-forming composition> in Example 1 was applied in a layer on a silicon wafer by spin coating, and heated on a hot plate at 120°C for 20 minutes to form a cured film (CO2 separation film) (film formation step). The amount of the film-forming composition applied on the silicon wafer in Examples 2 to 4 was changed so that the thickness of each film obtained in Examples 2 to 4 was different.

[0080] <Measurement of film thickness and surface roughness Ra> The film thickness and surface roughness Ra of the cured films obtained in Examples 2 to 4 were measured using DektakXT-S (manufactured by Bruker). The measurement conditions were a measurement range of 6.5 μm, a length of 30,000 μm, a period of 60 seconds, and a stylus pressure of 3 mg. The results are shown in FIG.

[0081] As shown in FIG. 6, in Examples 2 to 4, which used a film-forming composition containing polydimethylsiloxane, a curing agent, and hydroxamic acids, where the content of hydroxamic acids was more than 0 mass % and less than 5 mass % relative to the mass of polydimethylsiloxane, the surface roughness Ra of the produced cured film was 10% or less of the film thickness of the cured film, and it is clear that the film had a uniform thickness. [Explanation of symbols]

[0082] 1 Support 2 Sacrificial Layer 3 CO2 separation membrane 4 Supporting base material 10 Laminate 11 Rolls

Claims

1. The composition includes polydimethylsiloxane, a curing agent, and at least one hydroxamic acid selected from hydroxamic acid and a salt thereof, The film-forming composition, wherein the content of the hydroxamic acids is more than 0% by mass and less than 5% by mass relative to the mass of the polydimethylsiloxane.

2. The film forming composition according to claim 1 , wherein the polydimethylsiloxane has a mass average molecular weight of 90,000 or more.

3. CO ２ The film-forming composition according to claim 1 , which is a separation film-forming composition.

4. A cured film comprising a cured product of the film-forming composition according to any one of claims 1 to 3, A cured film, wherein the content of the hydroxamic acids is more than 0 mass % and less than 5 mass % relative to the mass of the cured film.

5. The cured film according to claim 4 , wherein the surface roughness Ra is 10% or less of the thickness of the cured film.

6. The cured film according to claim 4, having a film thickness of 10 nm or more and 2000 nm or less.

7. CO ２ The cured film of claim 4 which is a separation film.

8. A coating film forming step of forming a coating film of the film forming composition according to any one of claims 1 to 3; A curing step of curing the coating film to form a cured film, The method for producing a cured film, wherein the content of the hydroxamic acids in the cured film is adjusted to more than 0 mass% and less than 5 mass% in the curing step.

9. The cured film is ２ The method for producing the cured film according to claim 8 , which is a separation film.

10. CO ２ A method for producing a laminate in which a separation membrane and a supporting substrate are laminated, comprising the steps of: The method for producing a cured film according to claim 9 , ２ Manufacturing separation membranes, CO ２ A method for producing a laminate, comprising a separation membrane production step.

11. A laminate manufacturing process for manufacturing a laminate by the laminate manufacturing process according to claim 10; The laminate is coated with CO ２ By supplying a gas containing ２ A separation step of separating CO ２ Separation method.

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