Polymer material and its manufacturing method, gas absorbing material, and gas recovery device

Abstract

To develop a low water content polymer material while having gas reversible absorption performance, and provide an efficient production method of the polymer material at the same time.SOLUTION: A polymer material is an amine-containing polymer material including a polymer of a monomer mixture comprising a monofunctional monomer, and more than 10 mol% and 30 mol% or less of a polyfunctional monomer. An efficient production method of the polymer material includes: a polymer synthesis process of polymerizing monomers in a reaction mixture containing a monofunctional monomer, a polyfunctional monomer, a solvent, and an initiator to synthesize a polymer; and an amine-impregnating process of impregnating the polymer with amine, where the total monomer concentration of the reaction mixture is 0.7 mol / L or more, and the percentage of the polyfunctional monomer in monomers contained in the reaction mixture is more than 10 mol% and 30 mol% or less, provided that the amine-impregnating process needs not be performed when the monofunctional monomer has an amino group.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to polymeric materials and methods for their manufacture. [Background technology]

[0002] In recent years, global warming caused by carbon dioxide emitted from facilities such as thermal power plants, steel mills, and cement factories, and environmental pollution caused by harmful gases such as hydrogen sulfide have become problems, and research and development into gas separation and recovery is being carried out to prevent the effects of these gases. Among these research efforts is research into gas absorbents and gas separators that utilize the reversible gas absorption ability of polymer particles synthesized by polymerizing monomers with amino groups and monomers with hydrophobic groups. For example, Patent Documents 1 and 2 describe the production of polymer particles by adding 2,2'-azobis(2-methylpropionamidine) dihydrochloride as an initiator to a monomer mixture (total monomer concentration 0.312 mol / L) prepared by dissolving 55 mol% of N-(dimethylaminopropyl)methacrylamide, 43 mol% of N-tert-butylacrylamide, and 2 mol% of N,N'-methylenebisacrylamide in water, reacting the mixture, and freeze-drying the mixture. The resulting polymer particles can be formed into a film by methods such as spray-coating the aqueous dispersion onto a porous material, and the resulting film is shown to be useful as a reversible gas absorption material that absorbs carbon dioxide and then releases it when heated. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2016 / 024633 [Patent Document 2] International Publication No. 2017 / 146231 Summary of the Invention [Problem to be solved by the invention]

[0004] The present inventors have carried out investigations with the aim of developing a polymer material that has reversible gas absorption performance and low water content, and at the same time providing a method for efficiently producing this polymer material. [Means for solving the problem]

[0005] Specifically, the following solutions are provided:

[0006] [1] An amine-containing polymeric material comprising a polymer of a monomer mixture consisting of a monofunctional monomer and more than 10 mol % but not more than 30 mol % of a multifunctional monomer. [2] The polymer material according to [1], wherein the monofunctional monomer has an amino group. [3] The polymer material according to [1] or [2], wherein the polyfunctional monomer is N,N'-alkylenebis(meth)acrylamide. [4] The polymer material according to [1] or [2], wherein the polyfunctional monomer has an amino group. [5] The polymer material according to [1] or [2], wherein the polyfunctional monomer has a plurality of amino groups. [6] The polymer material according to any one of [1] to [5], wherein the polymer is a polymer polymerized using 2,2'-azobis(2-methylpropionitrile) as an initiator. [7] The polymer material according to any one of [1] to [6], wherein the polymer is polymerized in the presence of a surfactant. [8] The polymer material according to any one of [1] to [7], which contains a surfactant. [9] The polymer material according to [7] or [8], wherein the surfactant is cetyltrimethylammonium bromide.

[10] The polymer material according to any one of [1] to [9], which is a pulverized product.

[11] The polymer material according to any one of [1] to

[10] , which is a filtrate.

[12] The polymer material according to any one of [1] to

[11] , which is a dried product.

[13] The polymer material according to any one of [1] to

[12] , wherein the polymer is a polymer polymerized using water and alcohol as a solvent.

[14] The polymer material according to any one of [1] to

[13] , wherein the monomer mixture contains a monomer having a hydrophobic group.

[15] The polymer material according to any one of [1] to

[14] , which is a polymer material for gas absorption.

[16] The polymer material according to any one of [1] to

[15] , which is a polymer material for absorbing carbon dioxide gas.

[17] The polymer material according to any one of [1] to

[16] , which is capable of reversibly absorbing carbon dioxide gas.

[18] The polymer material according to any one of [1] to

[17] , wherein the water content of the polymer is 3 grams or less when 1 gram of the dry polymer is immersed in water at 30°C overnight.

[19] A polymer synthesis step of synthesizing a polymer by polymerizing monomers in a reaction mixture containing a monofunctional monomer, a polyfunctional monomer, a solvent, and an initiator; an amine impregnation step of impregnating the polymer with a treatment liquid containing an amine, the total monomer concentration of the reaction mixture is 0.7 mol / L or more; the proportion of the polyfunctional monomer in the monomers contained in the reaction mixture is 10 to 30 mol %, In the method for producing a polymer material, when the monofunctional monomer has an amino group, the amine impregnation step does not need to be carried out.

[20] The method for producing a polymer material according to

[19] , wherein the monofunctional monomer has an amino group and the amine impregnation step is performed.

[21] The method for producing a polymer material according to

[19] , wherein the monofunctional monomer has an amino group, and the amine impregnation step is not performed.

[22] The method for producing a polymer material according to any one of

[19] to

[21] , wherein the polyfunctional monomer is N,N'-alkylenebis(meth)acrylamide.

[23] The method for producing a polymer material according to any one of

[19] to

[21] , wherein the polyfunctional monomer has an amino group.

[24] The method for producing a polymer material according to any one of

[19] to

[21] , wherein the polyfunctional monomer has a plurality of amino groups.

[25] The method for producing a polymer material according to any one of

[19] to

[24] , wherein the initiator is 2,2'-azobis(2-methylpropionitrile).

[26] The method for producing a polymer material according to any one of

[19] to

[25] , wherein the reaction mixture contains a surfactant.

[27] The method for producing a polymer material according to

[26] , wherein the surfactant is cetyltrimethylammonium bromide.

[28] The method for producing a polymer material according to any one of

[19] to

[27] , wherein the polymer obtained in the polymer synthesis step is pulverized.

[29] The method for producing a polymer material according to any one of

[19] to

[28] , wherein the polymer obtained in the polymer synthesis step is filtered.

[30] The method for producing a polymer material according to any one of

[19] to

[29] , wherein the polymer obtained in the polymer synthesis step is dried.

[31] The method for producing a polymer material according to any one of

[19] to

[30] , wherein water and an alcohol are used as the solvent.

[32] The method for producing a polymer material according to any one of

[19] to

[31] , wherein the reaction mixture contains a monomer having a hydrophobic group.

[33] The method for producing a polymer material according to

[32] , further comprising the step of heating a mixture containing a monomer having an amino group, a polyfunctional monomer, and water, and then adding a monomer having a hydrophobic group to the mixture, prior to the polymer synthesis step.

[34] The method for producing a polymer material according to

[33] , wherein the monomer having a hydrophobic group is added in the form of an alcohol solution.

[35] The method for producing a polymer material according to any one of

[32] to

[34] , wherein the total monomer concentration in the reaction mixture is 3 mol / L or less.

[36] The method for producing a polymer material according to any one of

[19] to

[35] , which is a method for producing a polymer material for use as a gas absorbing material.

[37] A method for producing a polymer material for absorbing carbon dioxide gas according to any one of

[19] to

[36] .

[38] The method for producing a polymer material according to any one of

[19] to

[36] , which is a method for producing a polymer material capable of reversibly absorbing carbon dioxide gas.

[39] The method for producing a polymer material according to

[38] , wherein the water content of the polymer is 3 grams or less when 1 gram of the dry polymer is immersed in water at 30°C overnight.

[40] A polymer material produced by the production method according to any one of

[19] to

[39] .

[41] A gas-absorbing material containing the polymer material according to any one of [1] to

[18] and

[40] .

[42] The gas absorbing material according to

[41] , further comprising a thermoplastic resin.

[43] The gas absorbing material according to

[42] , wherein the thermoplastic resin is polyethylene.

[44] The gas absorbing material according to any one of

[41] to

[43] , further comprising a filler.

[45] The gas absorbing material according to

[44] , wherein the filler has gas adsorption ability.

[46] The gas absorbing material according to

[44] or

[45] , wherein the filler is a powder.

[47] The gas absorbing material according to any one of

[44] to

[46] , wherein the filler is a fine particle having a primary particle size of 1000 nm or less.

[48] ​​The gas absorbing material according to any one of

[44] to

[47] , wherein the fine particles have a water contact angle of 70° or more.

[49] The gas absorbing material according to any one of

[44] to

[48] , wherein the filler is carbon black.

[50] The gas absorbing material according to any one of

[44] to

[48] , wherein the filler is carbon black that has been treated to be water repellent.

[51] The gas absorbing material according to any one of

[44] to

[48] , wherein the filler is fumed silica.

[52] The gas absorbing material according to any one of

[44] to

[48] , wherein the filler is fumed silica that has been treated to be water repellent.

[53] The gas absorbing material according to any one of

[44] to

[48] , wherein the filler is a fluorinated resin powder.

[54] The gas absorbing material according to any one of

[44] to

[48] , wherein the filler is Teflon (registered trademark) powder.

[55] The gas absorbing material according to any one of

[44] to

[48] , wherein the filler is activated carbon or zeolite.

[56] The gas absorbing material according to any one of

[41] to

[55] , which is swollen with water.

[57] The gas absorbing material according to any one of

[41] to

[56] , which is hydrated with water vapor.

[58] The gas absorbing material according to

[57] , wherein carbon dioxide gas or bicarbonate ions are added when water is added.

[59] A gas absorbing cartridge filled with the gas absorbing material according to any one of

[41] to

[58] .

[60] A gas supply device comprising the gas absorbing material according to any one of

[41] to

[58] .

[61] A gas recovery device comprising the gas absorbing material according to any one of

[41] to

[58] .

[62] The gas recovery device according to

[61] , wherein after the gas is absorbed by the gas absorbing material, the gas is desorbed by increasing the temperature of the gas absorbing material.

[63] The gas recovery device according to

[61] , wherein the gas is absorbed and stored in the gas absorbing material, and then the partial pressure of the gas is reduced to desorb the gas.

[64] The gas recovery device according to

[61] , wherein after the gas is absorbed by the gas absorbing material, the gas is desorbed by passing water vapor through the gas absorbing material.

[65] The gas recovery device according to

[61] , wherein after the gas is absorbed by the gas absorbing material, the gas is desorbed by passing high-temperature water through the gas absorbing material.

[66] A gas recovery device according to any one of

[61] to

[65] , wherein when the gas is absorbed by the gas absorbing material, evaporation of water from the gas absorbing material suppresses the rise in temperature of the gas absorbing material due to the heat of the gas absorption reaction.

[67] The gas recovery device according to any one of

[61] to

[66] , wherein when the gas is absorbed by the gas absorbing material, the temperature of the gas absorbing material is lowered by passing a dry gas through the gas absorbing material.

[68] The gas recovery device according to any one of

[61] to

[67] , wherein the gas is an acidic gas.

[69] The gas recovery device according to any one of

[61] to

[67] , wherein the gas is carbon dioxide gas.

[70] The gas recovery device according to any one of

[61] to

[67] , wherein the gas is water vapor. [Effects of the Invention]

[0007] According to the method for producing a polymer material of the present invention, a polymer material having low water content and reversible gas absorption performance can be produced, and the produced polymer material can be effectively used as a reversible gas absorption material. A gas recovery device using the gas absorption material of the present invention can efficiently recover acidic gases such as carbon dioxide, water vapor, etc. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic diagram showing a first embodiment of a gas recovery device of the present invention. [Figure 2] FIG. 3 is a schematic view showing a second embodiment of the gas recovery device of the present invention. [Figure 3] This shows the particle size distribution of a mixture of various polymer pulverized materials and RY300 (polymer material containing fine particles). [Figure 4] 10 is a graph showing the amount of CO2 absorbed during the absorption process and the amount of CO2 emitted during the emission process for a polymer pulverized at the 7th milling point and a polymer material containing microparticles containing RY300 (Sample 18), and a polymer pulverized at the 7th milling point (Sample 19). [Figure 5]This is a graph showing the amount of CO2 absorbed during the absorption process of a microparticle-containing polymer material (Sample 18) containing RY300 and an amino group-containing polymer pulverized at 7 minutes, and a pulverized material (Sample 20) obtained by pulverizing a mixture of RY300 and an amino group-containing polymer pulverized at 1.5 minutes using a bead mill. DETAILED DESCRIPTION OF THE INVENTION

[0009] The present invention will be described in detail below. The following description of the constituent elements may be based on representative embodiments or specific examples, but the present invention is not limited to such embodiments. In this specification, a numerical range expressed using "to" means a range that includes the numerical values ​​before and after "to" as the lower and upper limits. In this specification, "(meth)acrylamide" means "acrylamide" and "methacrylamide," and "(meth)acrylate" means "acrylate" and "methacrylate."

[0010] <Polymer materials> The polymeric material can be, for example, an amine-containing polymeric material that includes a polymer of a monomer mixture consisting of a monofunctional monomer and more than 10 mole % and up to 30 mole % of a multifunctional monomer. The proportion of the polyfunctional monomer in the monomer mixture can be more than 10 mol % and 30 mol % or less, and can also be 15 mol % or more and 30 mol % or less. For example, the polymer material can be moderately crosslinked or polymerized under conditions that do not cause excessive swelling, and has a large amount of amines, while maintaining low water content even after immersion in water, allowing it to increase the reversible absorption of acidic gases such as carbon dioxide gas and water vapor. Furthermore, it can reversibly absorb large amounts of acid gas even under high humidity conditions, and can be used for a long period of time at a high packing rate per unit volume without swelling due to excessive water absorption, even when used in a high humidity environment. Furthermore, excessive water content can be avoided, and extra energy for adjusting the temperature of water when dissipating gases such as carbon dioxide by temperature control such as heating can be eliminated. The polymer material can be efficiently produced by the production method described below.

[0011] <Method of manufacturing polymer materials> The method for producing a polymer material includes, for example, a polymer synthesis step of synthesizing a polymer by polymerizing monomers in a reaction mixture containing a monofunctional monomer, a polyfunctional monomer, a solvent, and an initiator, and an amine impregnation step of impregnating the polymer with a treatment liquid containing an amine, in which the total monomer concentration in the reaction mixture is 0.7 mol / L or more and the proportion of polyfunctional monomers among the monomers contained in the reaction mixture is more than 10 mol % and 30 mol % or less. However, when the monofunctional monomer has an amino group, the above-mentioned amine impregnation step may not be carried out. In the method for producing a polymer material, by setting the total monomer concentration and the proportion of the polyfunctional monomer in the reaction mixture within the above ranges, a polymer material that has low water content but a large reversible gas absorption capacity can be efficiently obtained. Furthermore, a sufficient amount of polymer can be synthesized using a relatively small amount of solvent, which prevents the need for a large-scale production apparatus. Furthermore, the resulting polymer material has low swelling properties, and therefore when commercialized as a gas absorbent or gas separating material, a sufficiently large volume filling rate can be achieved. Each step will be described in detail below.

[0012] [1] Polymer synthesis process In this process, a polymer is synthesized by polymerizing monomers in a reaction mixture containing a monofunctional monomer, a polyfunctional monomer, a solvent, and an initiator. The following describes the monomers, solvents, initiators, and surfactants used as needed in the polymer synthesis process, as well as the polymerization reaction conditions and post-treatment of the polymer.

[0013] [Monofunctional monomer] A "monofunctional monomer" is, for example, a monomer having only one polymerizable group in the molecule. Examples of the polymerizable group include polymerizable groups having an ethylenically unsaturated group such as a vinyl group, an acryloyl group, a methacryloyl group, or a styrenyl group. The reversible gas absorption ability of the produced polymer is expressed, for example, by a reaction between an amino group and a gas component or a reaction between an amino group, a gas component, and water. The monofunctional monomer used here may, for example, have an amino group or may not have an amino group. Furthermore, a monofunctional monomer having no amino group and a monofunctional monomer having an amino group may be used in combination. When a monofunctional monomer having an amino group is used, the "amine impregnation step" described below does not need to be carried out. Examples of monofunctional monomers that do not have an amino group include acrylamide, methacrylamide, acrylic acid, acrylic acid salts, methacrylic acid, methacrylic acid salts, 2-acrylamido-2-methylpropanesulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid salts, N-alkylacrylamide, N-alkylmethacrylamide, alkyl acrylates, alkyl methacrylates, N,N-dialkylacrylamide, N-(hydroxyalkyl)acrylamide, (hydroxyalkyl)acrylates, N,N-dialkylmethacrylamide, N-(hydroxyalkyl)methacrylamide, and (hydroxyalkyl)methacrylates; other substituted (meth)acrylamides can also be used. Specific examples of monofunctional monomers having no amino group include N-methylacrylamide, N-ethylacrylamide, N-propylacrylamide, N-methylmethacrylamide, N-ethylmethacrylamide, N-propylmethacrylamide, methyl acrylate, ethyl acrylate, propyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, N,N-dimethylacrylamide, N,N-diethylacrylamide, N,N-dipropylacrylamide, N,N-dimethylmethacrylamide, N,N-diethylmethacrylamide, and N,N-dipropylmethacrylamide. Here, the terminal propyl group may be an n-propyl group or an isopropyl group. These monomers not having an amino group may be used alone or in combination of two or more. When the monofunctional monomer has an amino group, the amino group may be a primary amino group, a secondary amino group, or a tertiary amino group. The term "amino group" does not necessarily mean an amino group that constitutes an amide structure (-CO-NR2: R is a hydrogen atom or a substituent). The amino group of the monofunctional monomer may be designed to have an acid dissociation constant (pKa) as a conjugate acid. In order to increase the carbon dioxide absorption efficiency of the produced polymer, the acid dissociation constant (pKa) of the amino group in the carbon dioxide absorption environment can be made equal to or greater than the acid dissociation constant (pKa) of carbonic acid. Primary amino groups and some secondary amino groups form strong covalent bonds with carbon dioxide, and may not be able to release the carbon dioxide once absorbed. Therefore, when the monofunctional monomer has an amino group, the amino group may be a secondary amino group or a tertiary amino group, or may be a secondary amino group or a tertiary amino group having a hydroxyl group, an amide group, or an alkyl group nearby, or may be a dialkylamino group such as a dimethylamino group. Furthermore, the amine may be a monofunctional monomer having a cyclic amine such as piperidine or piperazine or a derivative thereof. If the acid dissociation constant of the amino group is too high, carbon dioxide may not be efficiently released during release. Therefore, it is possible to create a crowded environment around the amino groups in the gel by copolymerizing a monomer having a hydrophobic side chain with a monomer having an amino group or by introducing a certain amount of a polyfunctional monomer. The amino group in the monofunctional monomer may be bonded to a portion constituting the main chain of the polymer, or may be bonded to a portion constituting the side chain, or may be bonded to a portion constituting the side chain. The number of amino groups that the monofunctional monomer has is not particularly limited, and may be one or two or more. When a monomer has two or more amino groups, each amino group may be the same or different.

[0014] Examples of the monomer having an amino group include N-(aminoalkyl)acrylamides, N-(aminoalkyl)methacrylamides, aminoalkyl acrylates, and aminoalkyl methacrylates. In these monomers, the amino group may be substituted with a substituent such as an alkyl group. Specific examples of monomers having an amino group include N,N-dimethylaminopropyl methacrylamide, N,N-diethylaminopropyl methacrylamide, N,N-dimethylaminoethyl methacrylamide, N,N-diethylaminoethyl methacrylamide, N,N-dimethylaminopropyl methacrylate, N,N-diethylaminopropyl methacrylate, N,N-dimethylaminoethyl methacrylate, N,N-diethylaminoethyl methacrylate, N,N-dimethylaminopropyl acrylamide, N,N-diethylaminopropyl acrylamide, N,N-dimethylaminoethyl acrylamide, N,N-diethylaminoethyl acrylamide, 3-aminopropyl methacrylamide, 3-aminopropyl acrylamide, N,N-dimethylaminopropyl acrylate, N,N-diethylaminopropyl acrylate, N,N-dimethylaminoethyl acrylate, N,N-diethylaminoethyl acrylate, 3-aminopropyl methacrylate, and 3-aminopropyl acrylate. Alternatively, the compound may be a salt of an acidic substance, such as a hydrochloride or bicarbonate, or an acrylamide synthesized by condensing a commercially available oligoamine or polyamine having a primary or secondary amine with acrylic acid, methacrylic acid, or a derivative thereof. Furthermore, ethyleneimine, vinylamine, allylamine, allylamine hydrochloride, etc. can also be used as the monomer having an amino group. These monofunctional monomers having an amino group may be used alone or in combination of two or more.

[0015] [Multifunctional Monomer] A "polyfunctional monomer" is, for example, a monomer having two or more polymerizable groups in the molecule. Specific examples of polymerizable groups can be found in the [Monofunctional Monomer] section. The number of polymerizable groups in a polyfunctional monomer is not particularly limited, but can be 2 to 6, 2 to 5, 2 to 4, or 2. The multiple polymerizable groups in a polyfunctional monomer may be the same or different. By including a polyfunctional monomer in a predetermined ratio in the reaction mixture, a crosslinked structure is formed between polymer chains, resulting in a hard polymer with reduced water absorption and swelling. By copolymerizing an appropriate amount of polyfunctional monomer with a monomer having an amino group, hydrophobicity and steric hindrance are introduced around the amino group, lowering the acid dissociation constant of the amino group under carbon dioxide release conditions, allowing for the synthesis of a material that efficiently releases carbon dioxide. However, if the amount of polyfunctional monomer introduced is too large, the acid dissociation constant of the amino group under carbon dioxide absorption conditions will be too low, resulting in a decrease in carbon dioxide absorption. Therefore, it is important to design the amount of polyfunctional monomer introduced appropriately. Examples of polyfunctional monomers include polyfunctional (meth)acrylamide monomers, polyfunctional (meth)acrylate monomers, and crosslinkers such as titanium crosslinkers. An acrylamide monomer (acrylamide derivative) having two polymerizable groups can be used. An example of an acrylamide monomer having two polymerizable groups is N,N'-alkylenebis(meth)acrylamide. The number of carbon atoms in the alkylene group of N,N'-alkylenebis(meth)acrylamide is not particularly limited, but can be 1 to 12, 1 to 4, or 1 to 2. A specific example of an acrylamide derivative having two polymerizable groups is N,N'-methylenebisacrylamide (BIS). Alternatively, instead of the alkylene group, a crosslinking agent having a linear or cyclic crosslinking chain with an amino group, such as oligoethyleneimine, N,N'-bis(2-aminoethyl)-1,3-propanediamine, iminobispropylamine, methyliminobispropylamine, or 1,4-(bisaminopropyl)piperazine, can be used as the polyfunctional monomer. Similarly, instead of the alkylene group, a crosslinking agent having an oligoethylene glycol as the crosslinking chain can be used as the polyfunctional monomer. Furthermore, a specific example of a polyfunctional (meth)acrylate monomer is ethylene glycol dimethacrylate (EGDMA). These polyfunctional monomers may be used alone or in combination of two or more.

[0016] [Monomers with hydrophobic groups] The reaction mixture may include a monomer having a hydrophobic group. The term "hydrophobic group" can refer to a functional group that is sparingly soluble in water, such as an alkyl group or a phenyl group. The monomer having a hydrophobic group may be, for example, a monofunctional monomer having a hydrophobic group but not having an amino group, or may be a polyfunctional monomer having a hydrophobic group. A monofunctional monomer having both a hydrophobic group and an amino group can be classified as a “monofunctional monomer having an amino group,” and a polyfunctional monomer having a hydrophobic group can be classified as a “polyfunctional monomer.” Therefore, a monofunctional monomer having a hydrophobic group but not an amino group is referred to as a “monofunctional monomer having a hydrophobic group.” The hydrophobic group contained in the monomer may be, for example, C X H 2X Or C X H 2X+1 (X is an integer), and may be a methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, tert-butyl group, pentyl group, cyclopentyl group, isopentyl group, hexyl group, cyclohexyl group, etc. Furthermore, the hydrophobic group may be one in which a hydrogen atom of the above hydrophobic group has been substituted with a hydroxyl group, such as a hydroxyethyl group, a hydroxypropyl group, or a hydroxybutyl group. The hydrophobic group in the monomer may be bonded to the part constituting the main chain of the polymer or to the part constituting the side chain, but it can also be bonded to the part constituting the side chain. The number of hydrophobic groups possessed by the monomer is not particularly limited, and may be one or two or more. When the monomer has two or more hydrophobic groups, the respective hydrophobic groups may be the same or different.

[0017] Specific examples of monomers having a hydrophobic group include N-alkylacrylamides, N-alkylmethacrylamides, alkyl acrylates, alkyl methacrylates, N,N-dialkylacrylamides, N-(hydroxyalkyl)acrylamides, (hydroxyalkyl)acrylates, N,N-dialkylmethacrylamides, N-(hydroxyalkyl)methacrylamides, (hydroxyalkyl)methacrylates, N-phenylmethacrylamides, and N-phenylmethacrylates. These polymers having a hydrophobic group may be used alone or in combination of two or more.

[0018] [Monomer combination] Examples of combinations of monofunctional monomers and polyfunctional monomers include a combination of a monofunctional monomer having an amino group and a polyfunctional monomer, a combination of a monofunctional monomer having neither an amino group nor a hydrophobic group and a polyfunctional monomer, a combination of a monofunctional monomer having a hydrophobic group and a polyfunctional monomer, a combination of a monofunctional monomer having an amino group, a monofunctional monomer having a hydrophobic group and a polyfunctional monomer, and a combination of a monofunctional monomer having an amino group, a monofunctional monomer having neither an amino group nor a hydrophobic group and a polyfunctional monomer. Examples of combinations of monofunctional monomers having an amino group and polyfunctional monomers include a combination of N-(aminoalkyl)(meth)acrylamide and an acrylamide derivative having two polymerizable groups or a (meth)acrylate having two polymerizable groups. A specific example is a combination of N,N-dimethylaminopropyl(meth)acrylamide (DMAPM) and N,N'-methylenebisacrylamide (BIS). Examples of combinations of monofunctional monomers having an amino group, monofunctional monomers having a hydrophobic group, and polyfunctional monomers include combinations of N-(aminoalkyl)(meth)acrylamides, N-alkyl(meth)acrylamides, and acrylamide derivatives having two polymerizable groups or (meth)acrylates having two polymerizable groups. Specific examples include combinations of N,N-dimethylaminopropyl(meth)acrylamide (DMAPM), N-tert-butylacrylamide (TBAm), and N,N'-methylenebisacrylamide (BIS). Examples of combinations of monofunctional monomers and polyfunctional monomers that do not have amino groups or hydrophobic groups include a combination of N,N-dialkyl(meth)acrylamide with an acrylamide derivative having two polymerizable groups or a (meth)acrylate having two polymerizable groups, and a combination of N-alkyl(meth)acrylamide with an acrylamide derivative having two polymerizable groups or a (meth)acrylate having two polymerizable groups. Specific examples include a combination of N,N-dimethyl(meth)acrylamide (DMAm) with N,N'-methylenebisacrylamide (BIS), and a combination of N-isopropylacrylamide (NiPAm) with N,N'-methylenebisacrylamide (BIS).

[0019] [solvent] The solvent functions as a reaction medium for the polymerization reaction. By including a solvent in the reaction mixture, it is possible to synthesize a polymer with an appropriate amount of space around the amino groups in the polymer. Therefore, the polymer obtained by adding an appropriate amount of solvent for polymerization tends to have a high reversible gas absorption capacity. Examples of the solvent include polar solvents such as water, alcohol (e.g., methanol, ethanol, isopropanol), and dimethyl sulfoxide, and a mixed solvent of two or more of these polar solvents may also be used. Alternatively, water or a mixed solvent of water and another polar solvent may be used, or a mixed solvent of water and alcohol, water and ethanol, or water and methanol may also be used. The volume ratio of water to alcohol (water:alcohol) may be 1:0 to 1:1, 1:0.2 to 1:0.8, or 1:0.3 to 1:0.5. The solvent may contain salts or polymers soluble in the solvent.

[0020] [Initiator] Initiators are compounds added to initiate the polymerization reaction of monomers. They can be converted into highly reactive intermediates upon the application of energy. Examples include thermal polymerization initiators, which generate active species such as radicals and cations upon heating, and photopolymerization initiators, which generate active species such as radicals, cations, and anions upon light irradiation. Examples of initiators for thermal radical polymerization include azo compounds such as 2,2'-azobis(2-methylpropionitrile) (AIBN), 2,2'-azobisbutyronitrile, 2,2'-azobis(2,4-dimethylvaleronitrile) (V-65), and 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile) (V-70), as well as peroxides such as benzoyl peroxide, tert-butyl hydroperoxide, aqueous hydrogen peroxide, persulfates, and tert-butyl hydroperoxide + ferrous sulfate. Examples of initiators for thermal cationic polymerization include benzenesulfonate esters and alkylsulfonium salts. Examples of initiators that generate radicals upon irradiation with ultraviolet light or electron beams include benzoin derivatives, benzyl derivatives, acetophenone derivatives, benzophenone derivatives, and azo derivatives. The initiator such as AIBN may be used after purification (recrystallization) or without purification.

[0021] [Surfactants] If necessary, a surfactant or the like may be added to the reaction mixture, which allows the synthesis of a uniform polymer. As the additive, amphiphilic polymers such as polyethylene oxide, polyvinylpyrrolidone, polyvinyl alcohol, and oligomers thereof, or ionic surfactants such as cetyltrimethylammonium bromide can be used.

[0022] [Polymerization reaction] In the production method, a polymer is produced by polymerizing monomers in a reaction mixture containing the above-mentioned monofunctional monomer, polyfunctional monomer, solvent, and initiator, and the total monomer concentration in the reaction mixture can be 0.7 mol / L or more, and the proportion of polyfunctional monomers among the monomers contained in the reaction mixture can be more than 10 mol% and 30 mol% or less. Here, the "total monomer concentration" of the reaction mixture can refer to, for example, the total number of moles of all monomers contained in 1 L of the reaction mixture. Polymerization of the monomers in the reaction mixture results in the synthesis of a polymer having polymer chains containing structural units derived from monofunctional monomers and crosslinked structures derived from polyfunctional monomers. In this production method, the total monomer concentration of the reaction mixture can be set high, at 0.7 mol / L or higher, allowing the polymer chains to efficiently form non-covalent crosslinks through interactions and entanglement within the limited volume of the reaction mixture, and the polymer can be polymerized in a state where the structure is stabilized by covalent crosslinking with the crosslinking agent. As a result, the polymer does not absorb excessive moisture or deform in a wet state. A polymer with low swelling, i.e., a high reversible gas absorption per unit volume, can be synthesized in high yield while maintaining the reversible gas absorption per mass. Furthermore, the total monomer concentration can be set to 0.7 mol / L or more, and the proportion of polyfunctional monomers among the monomers can be set to 10 mol% or more, thereby allowing for the formation of relatively dense crosslinked structures between polymer chains. This results in a polymer that is hard and has low water content and swelling properties. Furthermore, the upper limit of the total monomer concentration can be set to 4 mol / L, and the upper limit of the proportion of polyfunctional monomers can be set to 30 mol%, thereby preventing a decrease in the reversible gas absorption capacity per mass due to these concentrations being too high. As a result, polymer materials with high reversible gas absorption capacity per unit volume can be produced with good productivity.

[0023] The total concentration of the monomers in the reaction mixture can be, for example, 1.0 to 2.8 mol / L, or 1.5 to 3 mol / L. The proportion of the polyfunctional monomer in the monomers can be, for example, more than 10 mol % and 30 mol % or less, or 15 mol % or more and 30 mol % or less. When the reaction mixture contains a monofunctional monomer having an amino group, the proportion of the monofunctional monomer having an amino group in the monomers can be, for example, 1 to 95 mol %, or 5 to 90 mol %, or 30 to 85 mol %. When the reaction mixture contains a monofunctional monomer having a hydrophobic group, the ratio of the monofunctional monomer having a hydrophobic group to the total monomers can be, for example, 1 to 50 mol %, or 5 to 45 mol %, or 10 to 43 mol %. When the reaction mixture contains a monofunctional monomer having an amino group and a monofunctional monomer having a hydrophobic group, the molar ratio of the monofunctional monomer having an amino group to the monofunctional monomer having a hydrophobic group can be, for example, 95:5 to 5:95, or 3:1 to 1:2.

[0024] The procedure for mixing the components of the reaction mixture is not particularly limited, but when a monofunctional monomer having an amino group and a monofunctional monomer having a hydrophobic group are used in combination, the mixture containing the monofunctional monomer having an amino group, the polyfunctional monomer, and water can be heated, and then the monofunctional monomer having a hydrophobic group can be added to the mixture, or the monofunctional monomer having a hydrophobic group can be added to the mixture as an alcohol solution. This allows the monomers to be mixed uniformly while keeping the amount of solvent small. The reaction temperature of the reaction mixture can be, for example, 0 to 200°C, or 30 to 120°C, or 50 to 105°C. The reaction time can be, for example, 0.1 to 5 hours, or 0.2 to 3 hours.

[0025] [Polymer post-treatment] In the production method of the present invention, a low-swelling polymer is formed as a precipitate in the reaction solution, or the entire reaction solution gels. The formed polymer may be mechanically pulverized to form a slurry or powder, or the liquid component may be removed from the reaction solution, and the remaining precipitate (polymer) may be mechanically pulverized to form a powder. Alternatively, the obtained powder may be suspended in a dispersion medium to prepare a slurry. The gel can be crushed using various crushers, such as a jaw crusher, a gyratory crusher, an impact crusher, a roll crusher, an edge runner, a disintegrator, a SAG mill, an autogenous crushing mill, a ball mill, a rod mill, a jet mill, an attritor, an extrusion / shear crusher, a meat chopper, or a Fitz mill. Alternatively, the prepared slurry may be applied and dried to form a porous membrane made of polymer powder, or the slurry may be filtered to leave a polymer film on the filter, which may then be dried to form a polymer film or packed layer. In the case of polymer particles used in conventional gas absorption materials, when the particles absorb moisture and swell, the particles swell and block the voids between the particles. This makes it difficult to remove the moisture between the particles, making filtration and drying difficult. In contrast, the polymer powder of the present invention has low swelling properties, so it can be easily molded into the shape of a membrane or a packed bed by methods such as filtration. The polymer molded into a membrane or packed can be stored and then redispersed in water to form a membrane or refill, or kneaded with a resin and molded. Examples of methods for applying the slurry include sand paper, spray coating, casting, bar coating, roll coating, wire bar coating, and dip coating. The polymer precipitate formed in the reaction solution, as well as the powder, slurry, and film prepared from the precipitate, may be freeze-dried or spray-dried. Alternatively, they may be dried with hot air using a fluidized bed. The polymer of the present invention retains appropriate swelling properties even when re-dispersed in water after freeze-drying without excessive water absorption. When re-swelling after drying, an acid such as hydrochloric acid or carbon dioxide may be added. Alternatively, a resin with low volatility and high hydrophilicity, such as polyethylene glycol or glycerin, may be added during drying to accelerate re-swelling. Furthermore, the powder, slurry, membrane prepared from the polymer precipitate, and freeze-dried products thereof can be washed as necessary and used as the gas-absorbing material described below.

[0026] [2] Amine impregnation process In the manufacturing method of the present invention, a polymer material is obtained by impregnating the polymer obtained in the polymer synthesis step [1] with a treatment liquid containing an amine (hereinafter referred to as "amine-containing treatment liquid"). However, if a monofunctional monomer containing an amino group is used in the polymer synthesis step [1], the amine impregnation step may not be performed. When a polymer is impregnated with an amine-containing treatment solution, the amine-containing treatment solution penetrates and diffuses between the polymer chains, resulting in the polymer containing amines. At this time, the polymer obtained in the above polymer synthesis process has a relatively dense crosslinked structure formed between the polymer chains, so it is resistant to swelling even when impregnated with the amine-containing treatment solution and maintains a hard state. The polymer material thus obtained exhibits excellent reversible gas absorption capacity, as gas diffusion is favorable during filling due to the suppressed swelling of the polymer, and the amino groups of the amine and those derived from the monofunctional monomer effectively function as functional groups that reversibly absorb gas. The amine-containing treatment solution used in the amine impregnation step and the conditions for the amine impregnation treatment will be described below.

[0027] [Amine-containing treatment solution] The amine-containing treatment liquid used in the amine impregnation step may be any liquid material containing amine, such as an amine solution prepared by dissolving amine in a solvent, or liquid amine. The amine-containing treatment liquid may also contain an appropriate amount of water.

[0028] (amine) The amine contained in the amine-containing treatment liquid may be either a low molecular weight amine or a high molecular weight amine. The molecular weight of the amine can be, for example, 61 to 10,000, or 75 to 1,000, or 90 to 500. For descriptions and specific examples of compounds that can be used as amines, please refer to the descriptions and specific examples of low molecular weight amines in the descriptions of absorption enhancers and diffusion enhancers below.

[0029] (solvent) When an amine solution is used as the amine-containing treatment liquid, the solvent can be, for example, a solvent that can dissolve the amine as a solute, has high compatibility with the polymer, and has high solubility for carbon dioxide and bicarbonate ions. Specific examples include water, ethylene glycol, and glycerin, and a mixed solvent of two or more of these solvents may also be used. The concentration of the amine in the amine solution can be, for example, 0.1 to 12N, or 1 to 10N, or 3 to 9N in terms of amine concentration.

[0030] (Other ingredients) The amine-containing treatment liquid may contain components other than the amine and the solvent (other components), such as an antioxidant.

[0031] [Conditions for amine impregnation treatment] Impregnation of the polymer with the amine-containing treatment liquid (amine impregnation treatment) can be carried out, for example, by immersing the polymer in the amine-containing treatment liquid. The polymer to be treated may be dried or swollen with a liquid such as water. When the polymer swollen with a liquid is immersed in an amine-containing treatment liquid, at least a portion of the liquid is replaced with the amine-containing treatment liquid, resulting in a polymer material containing the amine-containing treatment liquid or a mixture of the liquid and the amine-containing treatment liquid. The amount of the amine-containing treatment liquid used in the amine impregnation treatment can be, for example, 0.1 to 10 times, 0.2 to 5 times, or 0.3 to 3 times the mass of the polymer to be treated. The temperature of the amine-containing treatment liquid can be, for example, 5 to 100°C, or 10 to 80°C, or 15 to 60°C. The treatment time for the amine impregnation treatment varies depending on the concentration and temperature of the amine-containing treatment liquid, but can be, for example, 0.1 to 100 hours, 1 to 24 hours, or 2 to 12 hours. The amine impregnation treatment can be carried out while shaking the amine-containing treatment solution in which the polymer is immersed.

[0032] <Polymer materials> Next, the polymer material of the present invention will be described. The polymer material of the present invention is characterized by being produced by the production method of the present invention. For an explanation of the production method of the present invention, please refer to the description in the above section <Production method of polymer material>. The polymer material of the present invention may be categorized into two embodiments: (A) a polymer having a polymer chain containing a structural unit derived from a monofunctional monomer, a crosslinked structure derived from a polyfunctional monomer, and an amine derived from an amine-containing treatment solution; and (B) a polymer having a polymer chain containing a structural unit derived from a monofunctional monomer having an amino group, and a crosslinked structure derived from a polyfunctional monomer, but not containing a component derived from an amine-containing treatment solution. The monofunctional monomer in embodiment (A) and the polyfunctional monomer in embodiment (B) may or may not contain an amino group. The polymer material of the present invention can selectively absorb acidic gases such as carbon dioxide and hydrogen sulfide by containing an amino group in at least one of the structural units of the polymer and the impregnated amine. Furthermore, heating causes a phase transition, such as a decrease in pKa and an increase in hydrophobic interaction of hydrophobic groups, which dissipates the absorbed acidic gases. That is, the polymer material of the present invention has the reversible gas absorption ability to selectively and reversibly absorb acidic gases. Furthermore, because the polymer material of the present invention is produced by the production method of the present invention, it has low water absorption and swelling properties. Therefore, when commercialized as a gas absorbent or gas separation material, a sufficiently high volumetric filling rate can be achieved. Furthermore, when a gas containing moisture is passed through a gas recovery device using the product, the polymer absorbs water and swells, but it can only absorb a limited amount of water, limiting the degree of expansion. Therefore, sufficient gas flow paths can be secured, and the amount of heat required for the heating process for gas release can be reduced. Furthermore, even when liquid water is added to the absorbent material, the gaps between the hydrated polymers are maintained, ensuring sufficient water flow paths. Furthermore, subsequent gas flow allows the water to be easily expelled and gas to be introduced into the gaps. For these reasons, the polymer material of the present invention can be effectively used as a gas absorption material for reversibly absorbing acidic gases such as carbon dioxide, and the gas absorption material can be effectively used as a gas separation material for separating acidic gases from mixed gases. Below, the average molecular weight of the polymer contained in the polymer material of the present invention, the amount of each group when the polymer has an amino group or a hydrophobic group, the physical properties of the polymer, and the amine content when the polymer material contains an amine will be described.

[0033] [Average molecular weight of polymer, amount of amino group and hydrophobic group] When the polymer has amino groups, the amount of the amino groups can be, for example, 1 mmol / g to 23 mmol / g, or 1 mmol / g to 18 mmol / g, or 2 mmol / g to 7 mmol / g. Alternatively, the proportion of monomers having amino groups in all monomers can be, for example, 5 to 100 mol%, or 30 to 100 mol%, or 50 to 90 mol%. When the polymer has a hydrophobic group, the amount of the hydrophobic group can be, for example, 1 mol % to 50 mol %, or 5 mol % to 45 mol %, or 10 mol % to 43 mol %. The degree of crosslinking of the polymer can be, for example, 0 mol % to 50 mol %, or 5 mol % to 40 mol %, or 10 mol % to 30 mol %. When the polymeric material contains an amine, the content can be, for example, 1 to 30 mmol / g, or 2 to 20 mmol / g, or 3 to 10 mmol / g, of the dry weight of the polymer.

[0034] [Polymer swelling degree] The degree of swelling of the polymer contained in the polymer material of the present invention can be evaluated, for example, by the amount of water it contains when immersed in water for a long period of time.

[0035] [Water content of polymer] The polymeric material of the present invention may contain polymers that, when swollen with excess water, have a water content of, for example, 4 grams / gram polymer or less, or 3 grams / gram polymer or less, or 2 grams / gram polymer or less. Here, the "water content" of a polymer refers to the value calculated by the following formula, where M1 is the weight of the wet polymer after adding an excess amount of water, leaving the polymer to stand overnight at room temperature, and then pulverizing it with a hand blender, and filtering it through filter paper or a metal mesh to remove the water, and M0 is the weight of the polymer after drying by freeze-drying or natural drying. Water content = (M1-M0) / M0

[0036] [Reversible gas absorption capacity of polymer materials] The polymer material can have a reversible CO2 absorption capacity per dry polymer weight of, for example, 30 mL / g or more, 45 mL / g or more, or 60 mL / g or more. This allows the polymer material to efficiently absorb and capture carbon dioxide contained in exhaust gas when used in a gas recovery device that recovers carbon dioxide from exhaust gas. For the method for measuring the amount of reversible CO2 absorption, please refer to the description in the column (CO2 reversible absorption test) in the Examples.

[0037] [Polymer Material] The form of the polymer material of the present invention is not particularly limited, and may be, for example, any of a powder, a slurry, a film, a bulk body, etc. For the method of producing the powder, the slurry, or the film, the description in the section "Post-treatment of polymer" in the method of producing the polymer material can be referred to.

[0038] <Gas absorbing material> Next, the gas absorbing material of the present invention will be described. The gas absorbing material of the present invention contains the polymer material of the present invention. The gas absorbing material of the present invention contains the polymer material of the present invention, and therefore has a reversible gas absorption ability, absorbing acidic gases such as carbon dioxide and hydrogen sulfide or water vapor, and then discharging the acidic gas or water vapor in response to changes in temperature or gas partial pressure. For an explanation of the polymer material of the present invention, please refer to the description in the above section "Polymer Material." The gas-absorbing material of the present invention may contain, in addition to the polymer material of the present invention, components other than the polymer material of the present invention (other components). Examples of other components that can be used in the gas-absorbing material include moisture, pKa adjusters, absorption promoters, diffusion promoters, moisture absorbents, antioxidants, thermoplastic resins, and fillers. Moisture can be incorporated into the gas-absorbing material by intentionally adding moisture, for example, using water or water vapor. When adding moisture, carbon dioxide gas or bicarbonate ions can also be added.

[0039] [pKa adjuster] A pKa adjuster can be added, for example, during polymerization to adjust the pKa of the polymer after polymerization to a desired value. This allows for control of the type of gas absorbed by the polymer, the type of gas or liquid selectively permeating the gas absorption material, the permeation flux, the selectivity of the target gas to be absorbed relative to other gases, and the like. Examples of pKa adjusters include those capable of protonating or deprotonating the amino group of the polymer. For example, acids such as hydrochloric acid and bases such as sodium hydroxide can be used with concentrations adjusted appropriately according to the desired pKa. Furthermore, the crosslinking rate of a polyfunctional monomer can also adjust the local environment around the amine in the polymer, such as the polymer density, inter-amine distance, and polarity, thereby controlling the PKa of the amine. Therefore, the above-mentioned polyfunctional monomers may also be used as pKa adjusters. Furthermore, the addition of hydrophobic monomers, alcohols, or hydrophilic polymers during polymerization can also adjust the local environment around the amine, such as the polymer density, inter-amine distance, and polarity, thereby controlling the pKa of the amine. These may also be used as pKa adjusters.

[0040] [Absorption enhancer, diffusion enhancer] The absorption enhancer is a compound that functions to promote the absorption of acidic gases into the polymer of the present invention. The diffusion enhancer is a compound that functions to promote the diffusion of acidic gases from the polymer. In the present invention, an absorption / diffusion enhancer having both the functions of an absorption enhancer and a diffusion enhancer may be used. These absorption enhancers, diffusion enhancers, and absorption / diffusion enhancers may also function as stabilizers that stabilize the gas absorption material. The total content of the absorption enhancer, diffusion enhancer, and absorption / diffusion enhancer in the gas absorption material of the present invention can be, for example, 0.05 mL or more, or 0.1 mL or more per 1 g of solid content. Furthermore, the content of the absorption enhancer in the gas absorption material can be, for example, 0.1 to 12 N, 1 to 10 N, or 3 to 9 N in terms of amine concentration. Low molecular weight amines can be used as absorption enhancers, diffusion enhancers, and absorption / diffusion enhancers. The molecular weight of the low molecular weight amine may be, for example, 61 to 10,000, or 75 to 1,000, or 90 to 500. The boiling point of the low molecular weight amine is practical and can be, for example, 80°C or higher, or 120°C or higher, or 150°C or higher. To raise the boiling point, an amine-containing compound that has a moiety that forms a salt with a counter ion, like an ionic liquid, and is liquid may be used. The low-molecular-weight amine may contain any of a primary amino group, a secondary amino group, a tertiary amino group, an ammonium group, and an imidazolium group. The low-molecular-weight amine may contain a plurality of amino groups, ammonium groups, and imidazolium groups, for example, 1 to 3. The secondary amino group or tertiary amino group may be a cyclic amino group. Furthermore, the low-molecular-weight amine may contain a functional group other than an amino group, an ammonium group, or an imidazolium group, for example, a hydroxyl group. The low-molecular-weight amine may contain 0 to 2 hydroxyl groups. Examples of low-molecular-weight amines include amines having an amino group and a hydroxyl group, and amines having three amino groups, such as amines having a secondary amino group and a hydroxyl group. Because these amines can dramatically increase the amount of acidic gas emitted, particularly in the high-concentration range, and are suitable for repeated use, they may be selected, for example, from amines having a secondary amino group and a hydroxyl group with a boiling point of 150°C or higher. Examples of low molecular weight amines include specific compounds represented by the following formula:

[0041] [ka]

[0042] Among these, DMAE, IPAE, Bis(2DMAE)ER, 1-2HE-PRLD, 1-2HE-PP, TM-1,4-DAB, TMHAD, and PMDETA may be selected because they can particularly increase the amount of acidic gas emitted. Among these, IPAE, Bis(2DMAE)ER, 1-2HE-PP, TM-1,4-DAB, TMHAD, and PMDETA may be selected because they have a relatively high boiling point and are difficult to evaporate. IPAE, TM-1,4-DAB, TMHAD, and PMDETA may be selected because increasing their concentration can significantly increase the amount of acidic gas emitted. IPAE, TMHAD, and PMDETA may be selected because they are easily available.

[0043] [Moisture absorbent] The moisture absorbent that can be used as an additive is, for example, one that, when saturated with water, has a relative humidity of 90% or less at 25°C. Examples of such moisture absorbents include ions such as bromide ions, chloride ions, acetate ions, carbonate ions, bicarbonate ions, lithium ions, potassium ions, calcium ions, magnesium ions, and sodium ions. Other examples of such moisture absorbents include salts such as lithium bromide, lithium chloride, calcium chloride, potassium acetate, magnesium chloride, potassium carbonate, and sodium carbonate. When a moisture absorbent is added, the amount added can be, for example, 0.01 to 10% by mass of the total amount of the gas-absorbing material.

[0044] [Antioxidants] The antioxidants that can be used as additives are those that can suppress or prevent oxidation by adding them. Examples of such antioxidants include vitamin C (ascorbic acid), vitamin E (tocopherol), BHT (dibutylhydroxytoluene), BHA (butylhydroxyanisole), sodium erythorbate, propyl gallate, sodium sulfite, sulfur dioxide, hydroquinone, and derivatives thereof. When an antioxidant is added, the amount added can be, for example, 0.01 to 10% by mass based on the total amount of the gas absorbing material.

[0045] [Thermoplastic resin] The gas absorbing material may contain a thermoplastic resin, which can be kneaded with the polymer of the present invention and other components added as needed, and formed into pellets or a film. Known thermoplastic resins can be used. Examples include polyolefins such as polyethylene, polypropylene, and ethylene-vinyl acetate copolymers; liquid crystal polymers such as modified polyolefins, polyamides, thermoplastic polyimides, and aromatic polyesters; various thermoplastic elastomers such as polyphenylene oxide, polyphenylene sulfide, polycarbonate, polymethyl methacrylate, polyether, polyether ether ketone, polyetherimide, polyacetal, styrene-based, polyolefin-based, polyvinyl chloride-based, polyurethane-based, and polyester-based materials such as polyethyl lactate; polyamide-based, polybutadiene-based, trans-polyisoprene-based, fluororubber-based materials; and chlorinated polyethylene-based materials such as polyvinyl chloride and polyvinylidene chloride. These materials may also be used as copolymers, blends, or polymer alloys, including polyolefin-based resins such as polyethylene. When a thermoplastic resin is incorporated into the gas absorbing material, the content of the thermally activated resin can be, for example, 10 to 40% by mass of the total mass of the gas absorbing material.

[0046] [Filler] The gas absorbing material may contain a filler. This can form voids in the gas absorbing material, promoting gas diffusion into the gas absorbing material and improving the reversible gas absorption rate and reversible absorption amount. Furthermore, by using a filler with gas adsorption capacity, it is possible to achieve gas adsorption in the adsorbent in addition to the gas absorption of the absorbent material. Gas adsorbents are known to exhibit high reversible gas adsorption capacity at low humidity, while gas absorbing materials exhibit high gas absorption performance at high humidity. Therefore, using a gas adsorbent as a filler can achieve a material with high reversible gas adsorption capacity over a wide range of humidity conditions. Examples of fillers with gas adsorption capacity include materials with large pore areas, such as various types of activated carbon and zeolite. Adsorbents with particularly high carbon dioxide gas adsorption capacity may also be selected and used. Furthermore, when the polymer material constituting the gas absorbing material is gelled due to water or a pulverized gelled polymer (polymer pulverized product), adding a filler reduces the bulk, increasing the loading capacity and improving the reversible gas absorption capacity. As the filler, fine particles with a primary particle diameter of 1000 nm or less, as described below, are preferably used. Furthermore, the reversible gas absorption capacity can be further improved by pulverizing the gas absorbent material containing the pulverized polymer and the filler. The pulverization of the gas absorbent material containing the pulverized polymer and the filler can be carried out using a planetary ball mill using a bead mill or the like. To promote gas diffusion into the absorbent material, a powdered filler may be selected. Alternatively, a filler having an average primary particle size of, for example, 1000 nm or less may be used. The primary particle size here can be measured by observation with a transmission electron microscope. The fine particles having a primary particle size of 1000 nm or less used in the present invention may consist solely of fine particles having a primary particle size of 1000 nm or less. The particle size can be set to an average primary particle size of 0.1 nm to 1000 nm, or 0.3 nm to 500 nm, or 0.5 nm to 300 nm, or 1 nm to 200 nm, or 1.5 nm to 100 nm, or 2 nm to 50 nm, or 2.5 nm to 25 nm. This ensures the formation of a gas diffusion phase in the molded article of the gas absorbent material, which tends to further improve the gas absorption and diffusion rates. The fine particles may be aggregated primary particles. The aggregates preferably have a size of 100 nm to 200 μm, more preferably 500 nm to 100 μm, and most preferably 2.5 μm to 50 μm. Among fillers, those having a water contact angle of, for example, 70° or more may be used. The water contact angle may be 80° or more, 100° or more, 110° or more, 120° or more, 130° or more, or 140° or more.

[0047] Fine particles with a primary particle diameter of 1000 nm or less The fine particles having a primary particle diameter of 1000 nm or less that can be used as a filler will be specifically described below. The fine particles having a primary particle diameter of 1000 nm or less may be composed of an inorganic material, an organic material, or a combination of an organic material and an inorganic material. The fine particles may be water-repellent or hydrophilic, but are preferably water-repellent. By using water-repellent fine particles, the voids formed by the fine particles are prevented from being blocked by the moisture contained in the gas-absorbing material, and the voids function effectively as a gas diffusion phase. Here, "water-repellent fine particles" refers to fine particles having a primary particle diameter of 1000 nm or less and a water contact angle of 70° or more. The "water contact angle" of fine particles refers to the contact angle with water measured on the surface of a fine particle deposition film formed from the fine particles. The water contact angle of the fine particle deposition film surface can be measured by static water contact angle measurement. The water contact angle of the water-repellent microparticles is preferably 80° or more, more preferably 100° or more, even more preferably 110° or more, even more preferably 120° or more, particularly preferably 130° or more, and most preferably 140° or more.

[0048] (Water-repellent particles) The water-repellent fine particles having a primary particle diameter of 1000 nm or less may be fine particles that are water-repellent themselves, or may be base particles (base particles) whose surfaces have been given water-repellency. Examples of fine particles whose surfaces have been given water-repellency include coated fine particles in which a water-repellent coating is formed on the surface of a base particle, and surface-modified fine particles in which a surface modification is performed on a base particle to give water-repellency. First, carbon black can be cited as an example of fine particles that are water-repellent in themselves. Examples of carbon black include acetylene black, furnace black, channel black, thermal black, lamp black, and ketjen black, with acetylene black being preferred. Other examples of water-repellent fine particles include fine particles made of Knobel (porous carbon, manufactured by Toyo Tanso Co., Ltd.), titanium oxide, mesoporous silica, and the like. Furthermore, fine particles formed from a water-repellent organic material can also be used as fine particles that themselves have water repellency. Examples of water-repellent organic materials that can be used to form particles include -(CA 1 A 2 -CA 3 A 4 )-(wherein A 1 ~A 4represents a hydrogen atom, a fluorine atom, a chlorine atom or a perfluoroalkyl group, and A 1 ~A 4 (At least one of the groups is a fluorine atom.) Specific examples of fluororesins include polytetrafluoroethylene (PTFE), copolymers of tetrafluoroethylene and other monomers, polychlorotrifluoroethylene (PCTFE), copolymers of chlorotrifluoroethylene and other monomers, polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF), and polytetrafluoropropylene (HEP). Examples of copolymers of tetrafluoroethylene and other monomers include perfluoroalkoxyalkane (PFA: tetrafluoroethylene and perfluoroalkyl vinyl ether copolymer), perfluoroethylenepropene copolymer (FEP: tetrafluoroethylene and hexafluoropropylene copolymer), ethylene-tetrafluoroethylene copolymer (ETFE), and tetrafluoroethylene-perfluorodioxole copolymer (TFE / PDD). Examples of copolymers of chlorotrifluoroethylene and other monomers include ethylene-chlorotrifluoroethylene copolymer (ECTFE). These water-repellent organic materials may be used alone or in combination of two or more.

[0049] The base particles of the coated particles and surface-modified particles may be either inorganic or organic, but inorganic particles are preferred. Furthermore, when water-repellent particles are used as base particles and the particles are surface-modified to have a water-repellent coating or water-repellent properties, the gas absorption and desorption rates as well as the amount of gas absorbed and desorbed can be improved. Known inorganic particles can be used, including carbon blacks such as acetylene black, furnace black, channel black, thermal black, lamp black, and ketjen black; particles made of inorganic compounds such as oxides, hydroxides, nitrides, halides, carbonates, sulfates, acetates, and phosphates of metal or semi-metal elements; and natural mineral particles. Examples of inorganic compounds of metal or semi-metal elements include lithium fluoride, calcium carbonate, calcium phosphate, calcium sulfate, calcium fluoride, barium sulfate, titanium dioxide (titania), zirconia dioxide (zirconia), aluminum oxide (alumina), alumina silicates (alumina silicate, kaolin, kaolinite), and silicon oxide (silica, silica gel). Examples of natural minerals include talc and clay. Among these, particles made of carbon black and silicon oxide are preferred. Known organic particles can be used, including particles made of styrene-based, acrylic-based, melamine-based, benzoguanamine-based, and silicone-based polymers. In this case, a filler can be used in combination, and for example, activated carbon or zeolite can be preferably used as the filler.

[0050] The water-repellent coating formed on the base particles can be made of the water-repellent organic materials listed above as examples of water-repellent materials that can be used to form microparticles, as well as coatings of organopolysiloxanes and organohydrogenpolysiloxanes. Examples of organopolysiloxanes include dialkylpolysiloxanes and alkylphenylpolysiloxanes, and examples of organohydrogenpolysiloxanes include alkylhydrogenpolysiloxanes. The alkyl groups in dialkylpolysiloxanes, alkylphenylpolysiloxanes, and alkylhydrogenpolysiloxanes may be linear, branched, or cyclic, but are preferably linear. The number of carbon atoms in the alkyl group is preferably 1 to 20, more preferably 1 to 10, and even more preferably 1 to 6. Here, the two alkyl groups bonded to the silicon atom may be the same or different. Specific examples of organopolysiloxanes include dimethylpolysiloxane and methylphenylpolysiloxane, and specific examples of organohydrogenpolysiloxanes include methylhydrogenpolysiloxane.

[0051] Examples of surface modification methods for base particles include methods of introducing water-repellent groups such as alkyl groups and fluorinated alkyl groups onto the surfaces of base particles. The alkyl groups and fluorinated alkyl groups introduced into the base particles may be linear, branched, or cyclic, but are preferably linear. The number of carbon atoms in the alkyl groups and fluorinated alkyl groups is preferably 1 to 20, more preferably 1 to 15, and even more preferably 1 to 10. The fluorinated alkyl groups may be partially fluorinated alkyl groups in which some of the hydrogen atoms of the alkyl group are substituted with fluorine atoms, or may be perfluoroalkyl groups in which all of the hydrogen atoms are substituted with fluorine atoms.

[0052] The surface modification of the base particles by introducing these water-repellent groups can be carried out using a silane coupling agent or a silane compound such as silazane. Examples of the silane coupling agent include compounds represented by the following general formula (1): General formula (1) R 1 n Six (4-n) In the general formula (1), X represents a hydrolyzable group that generates a silanol group upon hydrolysis, and R 1 represents a group containing a water-repellent group, and n is an integer of 1 to 3. The silane coupling agent represented by general formula (1) introduces water-repellent groups into the base particle by reacting the silanol group or silyl group generated by hydrolysis of X with the functional group on the surface of the base particle. In the general formula, examples of the "hydrolyzable group that generates a silanol group" represented by X include alkoxy groups such as methoxy and ethoxy groups, and halogen groups. R 1 Examples of the water-repellent group in the above formula include alkyl groups, fluorinated alkyl groups, and dimethylsiloxane. The description and preferred ranges of the alkyl groups and fluorinated alkyl groups can be found in the description and preferred ranges of the water-repellent groups that can be introduced onto the surface of the base particle. The water-repellent group may be bonded directly to Si or via a linking group. n is an integer of 1 to 3, preferably 1 or 2. When n is 2 or more, a plurality of R 1 may be the same or different from each other. When n is 2 or less, multiple Xs may be the same or different from each other. Examples of silane coupling agents represented by general formula (1) include triethoxyalkylsilane, diethoxydialkylsilane, ethoxytrialkylsilane, trimethoxyalkylsilane, dimethoxydialkylsilane, methoxytrialkylsilane, trichloroalkylsilane, etc. Specific examples of silane coupling agents include triethoxycaprylylsilane (triethoxy-n-octylsilane), octadecyltrichlorosilane, etc. The formation of the water-repellent coating on the base particles and the surface modification treatment can be carried out according to conventional methods.

[0053] Commercially available water-repellent microparticles include Microdispers-200 (manufactured by Techno Chemical Co., Ltd.), AEROSIL RY200, AEROSIL RY300, AEROSIL R805 (all manufactured by Evonik), and Ketjenblack (manufactured by Lion Specialty Chemicals Co., Ltd.). The above water-repellent fine particles may be used singly or in combination of two or more kinds.

[0054] (Fine particles other than water-repellent fine particles) The fine particles having a primary particle diameter of 1000 nm or less that can be used as a filler are not limited to water-repellent fine particles, but may be fine particles other than water-repellent fine particles, i.e., fine particles having a water contact angle of less than 70°. Furthermore, water-repellent fine particles may be used in combination with fine particles having a water contact angle of less than 70°. The fine particles having a water contact angle of less than 70° may have a water contact angle of 50° or less, 30° or less, or 10° or less. The lower limit of the water contact angle of the fine particles is 0°. Examples of fine particles other than water-repellent fine particles include particles made of inorganic compounds of metal elements and semimetal elements and organic particles, which were described above as examples of base particles for coated fine particles and surface-modified fine particles in the section (Water-repellent fine particles), and it is preferable to use silicon oxide particles. Furthermore, these inorganic particles and organic particles may have a coating of an organic compound formed on their surface, or an organic functional group may be introduced therein. A commercially available product of fine particles other than water-repellent fine particles is AEROSIL 200 (manufactured by Evonik).

[0055] (specific surface area of ​​fine particles) The specific surface area of ​​the particles is 1 to 3000 m 2 / g, and 2.5 to 2750m 2 / g, and more preferably 5 to 2500m 2 This more reliably forms a gas diffusion phase in the molded article of the gas absorbing material, and tends to further improve the gas absorption rate and gas release rate. The specific surface area of ​​the fine particles can be measured by the BET method.

[0056] The ratio of polymer material to fine particles with a primary particle diameter of 1000 nm or less The weight ratio of the polymer material to the fine particles (polymer material:fine particles) is preferably 95:5 to 5:95, more preferably 90:10 to 30:70, and even more preferably 80:20 to 50:50. The content of the polymer material in the gas absorbent material, in terms of solid content, is preferably greater than the content of the water-repellent fine particles. When the polymer material is gelled by water or is a pulverized gelled polymer, adding a filler to the gas absorbent material reduces the bulk, increases the loading capacity, and improves the reversible gas absorption performance. To effectively achieve this effect, the volume ratio of the gelled polymer or its pulverized material to the fine particles (gelled polymer or its pulverized material:fine particles) is preferably 99.9:0.1 to 98:2, more preferably 99.75:0.25 to 98.5:1.5, and even more preferably 99.5:0.5 to 99:1. By setting the ratio of the polymer material to the fine particles within the above range, the gas absorption rate and the gas emission rate tend to be higher. However, the gas absorbing material of the present invention is not limited to those containing fine particles having a primary particle diameter of 1000 nm or less. In other words, the gas absorbing material of the present invention does not have to contain fine particles having a primary particle diameter of 1000 nm or less.

[0057] Other fillers In addition to the fine particles exemplified above, known fillers can be used in the gas absorbing material of the present invention. For example, activated carbon, zeolite, silica, fumed silica, hydrophobized silica, hydrophobized fumed silica, water-repellent silica, alumina, hydrophobized alumina, water-repellent alumina, boehmite, diatomaceous earth, oxides such as titanium oxide, iron oxide, zinc oxide, magnesium oxide, and metal ferrite, hydroxides such as aluminum hydroxide and magnesium hydroxide, carbonates such as calcium carbonate (light and heavy), magnesium carbonate, dolomite, and dawsonite, sulfates or sulfites such as calcium sulfate, barium sulfate, ammonium sulfate, and calcium sulfite, talc, mica, clay, glass fiber, Examples of suitable fillers include silicates such as calcium silicate, montmorillonite, and bentonite; borates such as zinc borate, barium metaborate, aluminum borate, calcium borate, and sodium borate; carbon such as carbon black, hydrophobic carbon black, water-repellent carbon black, graphite, and carbon fiber; and other materials such as iron powder, copper powder, aluminum powder, zinc oxide, molybdenum sulfide, boron fiber, potassium titanate, lead zirconate titanate, fluorinated resin powder, and Teflon® powder. Hydrophobic materials can also be selected and used to suppress water vapor condensation and dew condensation. Carbon fillers such as carbon black can also be selected and used. These fillers may have a primary particle diameter of 1000 nm or less or greater than 1000 nm. The gas-absorbing material of the present invention may also contain particles made of the same materials as those exemplified as fine particles having a primary particle diameter of 1000 nm or less, but having a primary particle diameter greater than 1000 nm. When a filler is contained in the gas absorbing material, the content of the filler can be, for example, 0.1 to 60 mass % relative to the total amount of the gas absorbing material.

[0058] [Dispersion medium] The gas-absorbing material may contain a dispersion medium for suspending the polymer material of the present invention and the additive. For preferred ranges and specific examples of the dispersion medium, please refer to the description in the [Solvent] section of the method for producing a polymer material.

[0059] The other components that can be used in the gas absorbing material explained above may be used alone or in combination of two or more.

[0060] <Use of gas absorbing material> The gas absorbing material containing the polymer material of the present invention can be used in various ways. Examples of ways to use the gas absorbing material include filling a container such as a drum with the gas absorbing material, forming the gas absorbing material into a sheet and forming a laminate or roll with a nonwoven fabric or mesh, filling the inside of a filter with the gas absorbing material, kneading the gas absorbing material with a hard material such as polyethylene and forming it into a free-standing film, fiber, or pellet, supporting a film of the gas absorbing material on a carrier, or filling the inside of a honeycomb structure with gas absorber powder. When the gas absorbing material is formed into a sheet or film, its thickness is not particularly limited, but can be, for example, 1 to 10,000 μm, 10 to 5,000 μm, or 100 to 1,000 μm. When the gas absorbing material is supported by a carrier, the carrier can be a thin plate, a fiber assembly, etc. The thin plate and the fiber assembly that can be used as the carrier will be described below.

[0061] [Thin plate] The thin plate may be a flat plate, sheet, or foil having a thickness of, for example, 2 mm or less and 5 μm or more. The material of the thin plate has a specific heat capacity of 2500KJ / (m 3 A thin plate having such thermal properties can change temperature quickly in response to changes in the external temperature, and can efficiently transmit the temperature change to the entire gas absorption material. Herein, the term "constant pressure specific heat" refers to a value measured by a calorimeter such as a water calorimeter or a differential scanning calorimeter, and the term "thermal conductivity" refers to a value measured by a laser flash method or a steady heat flow method.

[0062] Examples of thin plates that can be used include thin metal plates (metal foils), sheets made of carbon materials, carbon sheets, and resin films (polymer compound films). Examples of sheets made of carbon materials include graphite sheets, and examples of resin films include polyethylene, polypropylene, PET, and polyimide. Thin aluminum plates, thin iron plates, and graphite sheets may be used as thin plates because of their high thermal conductivity. Thin aluminum plates, graphite sheets, and resin films may also be used because of their low specific heat. Examples of thin metal plates include stainless steel plates, thin iron plates, thin aluminum plates, and thin nickel plates. Of these, thin iron plates, thin aluminum plates, and thin nickel plates may be particularly selected because of their relatively high thermal conductivity.

[0063] The thin plate may be a plate with a homogeneous internal structure, or may be a porous body or a honeycomb structure. In the case of a porous body or a honeycomb structure, the pores can be filled with a gas absorption material, which allows heat from the thin plate to be easily transferred to the gas absorption material, thereby improving the responsiveness of the gas absorption material to temperature changes. In particular, porous bodies such as foamed metal, foamed nickel, and porous carbon have high heat conductivity to gas absorption materials, and by using them as carriers, the responsiveness of the gas absorption material to temperature changes can be greatly improved. The pore diameter of porous bodies such as foamed metal can be, for example, 0.1 to 10 mm, or 0.4 to 4 mm. The specific surface area can be, for example, 100 to 10,000 m 2 / m 3 , or 200 to 6000 m 2 / m 3 Furthermore, if a carrier made of porous resin or porous carbon is used as the porous carrier, the thermal efficiency of the absorber can be improved due to its small heat capacity. The porous body used as the carrier may be selected from those having a porosity of, for example, 1 to 99%, 10 to 99%, or 20 to 95%. In this specification, the term "porosity of a thin plate" refers to the porosity measured by the apparent volume and mass of the thin plate and the density of the material. The carrier may also be a laminate of a plurality of these thin plates. In the laminate, all the thin plates may be the same, or a plurality of thin plates of different materials or thicknesses may be combined.

[0064] [Fiber assembly] A fiber assembly is a material obtained by processing a large number of fibers into a thin, wide plate. Examples of fiber assemblies include cloth and paper, with porous materials such as filters being preferred. The cloth may be woven, felt, or nonwoven. Sintered metal fiber felt can also be used as a carrier. This material has a densely packed structure of sintered fiber fibers, and can provide high thermal conductivity. For example, sintered stainless steel fiber felt or sintered nickel fiber felt can be used, with sintered nickel fiber felt being particularly suitable. The fibers used in the fiber assembly have a specific heat capacity at constant pressure of, for example, 2500 KJ / (m 3 It is also possible to use a fiber assembly having a thermal conductivity of 10 W / (mK) or less, or a thermal conductivity of 10 W / (mK) or more. A fiber assembly having such thermal properties changes temperature responsively in response to changes in the external temperature, and can efficiently transmit the temperature change to the entire gel membrane.

[0065] The fibers used in the fiber assembly may be inorganic fibers, organic fibers, or composite fibers that combine inorganic and organic fibers. Examples of inorganic fibers include stainless steel fibers, aluminum fibers, metal fibers such as nickel fibers, and carbon fibers. Nickel fibers may be selected because of their high thermal conductivity. Examples of organic fibers include natural fibers such as cotton and hemp, and synthetic fibers such as rayon and polyester. The diameter of the fibers is not particularly limited, but for example, fibers having a diameter of 8 to 100 μm can be used, which makes it possible to obtain a membrane of the gas absorbing material having excellent gas absorption and diffusion properties. The carrier may also be an assembly in which a plurality of these fiber assemblies are laminated together. In the assembly, the fiber assemblies may all be the same, or a plurality of fiber assemblies with different fiber types, fiber diameters, fiber densities, etc. may be combined. The carrier may also be a laminate in which a thin plate and a fiber assembly are laminated together.

[0066] The shape of the carrier is not particularly limited and can be appropriately selected depending on the application. Specific examples of the shape of the carrier include a plate shape and a cylinder shape, and the planar shape of the plate and the cross-sectional shape of the cylinder may be any of polygonal shapes such as square or rectangular, perfect circle, ellipse, etc. The gas absorbing material supported on a carrier can be formed by applying a slurry or powder of the gas absorbing material to the surface of the carrier, or by laminating a pre-formed film of the gas absorbing material to the surface of the carrier. A binder may be used to stably fix the slurry or powder of the gas absorbing material to the carrier.

[0067] <Gas recovery device> As described above, the gas absorbing material of the present invention can reversibly absorb acidic gases such as carbon dioxide and water vapor, and because the polymer component has low swelling, its volumetric filling rate can be increased when commercialized as a gas absorbent or the like. Therefore, it can be suitably used, for example, as a material for a gas absorber in a gas recovery device that selectively recovers carbon dioxide from exhaust gas. Below, first and second embodiments of a gas recovery device using the gas absorbing material of the present invention are described. FIG. 1 is a schematic diagram showing the gas recovery device of the first embodiment, and FIG. 2 is a schematic diagram showing the gas recovery device of the second embodiment.

[0068] As shown in Fig. 1, the gas recovery device of the first embodiment includes a heat exchanger 21, a desulfurizer 22, a cylindrical gas absorber 23, and first to third pipes 24, 25, and 26 connected to these components. One end of the first pipe 24 serves as a gas inlet for introducing exhaust gas (gas to be treated), and the other end is connected to the desulfurizer 22. One end of the second pipe 25 is connected to the desulfurizer 22 and the other end is connected to one side of the gas absorber 23. The third pipe 26 has a circulation path 26a connected to, for example, one side and the other side of the gas absorber 23, and a branch path 26b branching from the circulation path 26a on one side of the gas absorber 23, and one end of the branch path 26b serves as a gas outlet for discharging the recovered carbon dioxide gas. Furthermore, the connecting portions of the second pipe 25 and the third pipe 26 on one side of the gas absorber 23 are provided, for example, on approximately the same diameter of the circular side surface, with the center sandwiched between them. The heat exchanger 21 is connected to the middle part of the first pipe 24 and the middle part of the circulation path 26a. The gas absorber 23 is made of the gas absorbing material of the present invention, and when the operation of the gas recovery device is OFF, its temperature is approximately the same as the ambient temperature. The gas absorber 23 may be formed in a filter shape and disposed at a position where at least a part of it passes through the gas flow path in the gas recovery device. Furthermore, the gas absorber 23 may not be in the form of a filter, but may be disposed at a position at least partially outside the gas flow path in the gas recovery device.

[0069] To recover carbon dioxide from flue gas using this gas recovery device, the operation of each component is turned on, and high-temperature flue gas with dust collection is introduced into one end of the first pipe 24. The introduced flue gas passes through the first pipe 24 and is introduced into the desulfurizer 22, which has a cooling capacity of approximately 30°C. Here, the desulfurizer and the cooler may be separate devices. Furthermore, the temperature of the gas after passing through the desulfurizer 22 with cooling capacity does not need to be 30°C, but may be approximately 40°C or 50°C. When passing through the first pipe 24, a portion of the heat of the flue gas is transferred to the circulation path 26a of the third pipe 26 via the heat exchanger 21, and the temperature is adjusted so that the gas temperature or dew point temperature of the gas in the circulation path 26a is approximately 60°C. The gas in the circulation path 26a may be heated by heated water. The temperature or dew point temperature of the gas in the circulation path 26a may be 60°C or higher, and may be approximately 75°C or 85°C. Furthermore, the gas in the circulation path 26a may be depressurized. When the gas in the circulation path 26a is decompressed and the gas in the circulation path 26a is heated by heated water, there may be no gas flow in the circulation path 26a, or the gas flow rate may be extremely low. The flue gas introduced into the desulfurizer 22 is desulfurized in the desulfurizer 22 and then flows into the second pipe 25. The flue gas that flows into the second pipe 25 has a temperature or dew point temperature of approximately 30°C and is introduced into the gas absorber 23 at around this temperature. In the gas absorber 23, since the temperature of the flue gas is approximately 30°C, the absorber is cooled in the area where the flue gas comes into contact, and acidic gases such as carbon dioxide are efficiently absorbed by the gas absorbent material, while gases other than carbon dioxide are discharged to the outside of the gas absorber 23. When the dew point temperature of the flue gas is lower than the temperature of the absorbent material, the absorbent material and the flue gas are effectively cooled by the evaporation of water from the absorbent material, allowing for optimal temperature control. Furthermore, if the cooling of the absorber by the cooled exhaust gas is insufficient, additional cooling can be performed, such as by introducing a cooling gas or cooling using the latent heat of evaporation of water by reducing the pressure or introducing a dry gas. Meanwhile, the region of the gas absorber 23 that has absorbed carbon dioxide moves to the vicinity of the connecting portion of the third pipe 26 due to the rotation of the gas absorber 23, and comes into contact with the gas introduced from the circulation path 26a of the third pipe 26.The gas introduced through the circulation path 26a is heated to approximately 75°C through heat exchange with the exhaust gas. In the gas absorber 23 in the region where the gas comes into contact, the gas absorbent material is heated, and acidic gases such as carbon dioxide are released. In this case, if the dew point temperature of the gas in the circulation path 26a is higher than the temperature of the absorbent material, the absorbent material is more effectively heated by the heat of condensation of water vapor, which is preferable. Even when the gas in the circulation path 26a is decompressed, the reduced carbon dioxide partial pressure allows for effective release of carbon dioxide. A portion of the released carbon dioxide flows into the branch path 26b of the third pipe 26 and is discharged to the outside through the gas outlet of the branch path 26b and recovered. Another portion of the released carbon dioxide flows into the circulation path 26a of the third pipe 26. The carbon dioxide that flows into the circulation path 26a is heated or humidified by the heat exchanger 21 along the circulation path 26a, then reintroduced into the gas absorber 23, where its heat is used to heat the gas absorbent material.

[0070] As described above, in the carbon dioxide gas recovery device of the first embodiment, the heat of the exhaust gas is reused to heat the gas absorber, and switching is performed from a state in which acid gas is absorbed to a state in which it is released. In this embodiment, the heat of the exhaust gas is effectively utilized, so the amount of energy consumed in the carbon dioxide gas separation and recovery process can be significantly reduced. In the first embodiment, if the temperatures of the exhaust gas and the gas absorber cannot be controlled to temperatures suitable for carbon dioxide absorption and release, temperature control can be improved by adding an external heat exchange mechanism or an additional heating mechanism to the piping and absorber.

[0071] Next, a second embodiment of the gas recovery device will be described. As shown in FIG. 2 , the gas recovery system of the second embodiment includes a first heat exchanger 31, a second heat exchanger 32, a desulfurizer 33, a first tank 34, a second tank 35, and a first pipe 36 and a second pipe 37 connected to these components. One end of the first pipe 36 is a gas inlet for introducing exhaust gas (gas to be treated), and the other end is connected to the desulfurizer 33, which has cooling capacity. The desulfurizer and the cooler may be separate devices. The second pipe 37 includes a main path 37a, one end of which is connected to the desulfurizer 33, and a first path 37b and a second path 37c, which branch off from the other end of the main path 37a. One end of the first path 37b is connected to the main path 37a, and the other end is connected to the first tank 34. The second path 37c is connected to the main path 37a, and the other end is connected to the second tank 35. Valves (not shown) for opening and closing the first and second paths 37b, 37c are provided near the other ends of the first and second paths 37b, 37c. The first heat exchanger 31 is connected to a first intermediate portion of the first pipe 36 and the first tank 34, and the second heat exchanger 32 is connected to a second intermediate portion of the first pipe 36 and the second tank 35. In the gas recovery device of the second embodiment, gas absorption materials (gas absorbers) 38, 39 are formed on the heat exchange surface of the first heat exchanger 31 in the first tank 34 and the heat exchange surface of the second heat exchanger 32 in the second tank 35, respectively, and when the operation of the gas recovery device is OFF, each gas absorber 38, 39 is at a temperature similar to the ambient temperature (approximately 30°C).

[0072] To recover carbon dioxide gas from flue gas using this carbon dioxide gas recovery device, first, the valve of the first path 37b of the second pipe 37 is opened, the valve of the second path 37c of the second pipe 37 is closed, the first heat exchanger 31 is turned off, and the second heat exchanger 32 is turned on. In this state, the first tank 34 functions as an absorption tower. That is, in this state, when high-temperature post-dust collection flue gas is introduced into one end of the first pipe 36, the introduced flue gas passes through the first pipe 36 and is introduced into the desulfurizer 33. As the flue gas passes through the first pipe 36, part of the heat of the flue gas is transferred to the second tank 35 via the second heat exchanger 32, and the flue gas is cooled. The flue gas introduced into the desulfurizer 33 is subjected to desulfurization treatment in the desulfurizer 33, which has cooling capacity, and after further cooling, flows into the main path 37a of the second pipe 37. The temperature or dew point temperature of the exhaust gas that flows into the main path 37a is about 30°C, and the exhaust gas is introduced into the first tank 34 via the main path 37a and the first path 37b at around this temperature. In the first tank 34, the temperature or dew point temperature of the exhaust gas is about 30°C, so that the gas absorber 38 is efficiently cooled, resulting in efficient absorption of carbon dioxide, and gases other than carbon dioxide are discharged to the outside from a gas outlet provided in the first tank 34. The temperature or dew point temperature of the exhaust gas that flows into the main path 37a and cools the absorber does not have to be 30°C, and may be about 40°C or 50°C.

[0073] After the gas absorber 38 has sufficiently absorbed carbon dioxide, the valve of the first path 37b of the second pipe 37 is switched to a closed state, the valve of the second path 37c of the second pipe 37 is switched to an open state, the first heat exchanger 31 is switched to an ON state, and the second heat exchanger 32 is switched to an OFF state. Thus, heat from the exhaust gas passing through the first pipe 36 is transferred to the first tank 34 and the gas absorber 38 via the first heat exchanger 31. The first heat exchanger 31 preferably uses water as a heat medium, and the gas absorber 38 is heated by introducing heated water or steam. The gas absorber 38 in the first tank 34 is heated to approximately 75°C by the heat from the first heat exchanger 31, and then dissipates carbon dioxide. The temperature of the heated gas absorber 38 may be approximately 60°C or 85°C. The gas absorber 38 may be depressurized during heating. The dissipated carbon dioxide is discharged from a gas outlet provided in the first tank 34 and collected. Meanwhile, flue gas at approximately 30°C that has flowed into the second pipe 37 via the same route as above is introduced into the second tank 35 via the second path 37c, and carbon dioxide is absorbed by the gas absorber 39 installed in that tank 35. When the dew point temperature of the flue gas is lower than the temperature of the absorbent material, the absorbent material and flue gas are effectively cooled by the evaporation of water from the absorbent material, which is preferable. Furthermore, if the cooled flue gas does not sufficiently cool the absorber, it is desirable to perform additional cooling, such as by introducing a cooling gas or cooling using the latent heat of evaporation of water by reducing pressure or introducing a dry gas. In other words, in this state, the first tank 34 functions as a stripper, and the second tank 35 functions as an absorber, and the absorption and stripping of carbon dioxide gas occur in parallel.

[0074] After sufficient carbon dioxide desorption from the gas absorber 38 and absorption into the gas absorber 39, as shown in FIG. 2, the valve of the first path 37b of the second pipe 37 is opened, the valve of the second path 37c of the second pipe 37 is closed, the first heat exchanger 31 is turned off, and the second heat exchanger 32 is turned on, switching the first tank 34 to function as an absorption tower and the second tank 35 to function as a stripper tower. This allows carbon dioxide gas absorption and stripping to occur in parallel in the opposite towers from before the switchover. Furthermore, by repeatedly performing the above-described switching operation, carbon dioxide gas can be continuously absorbed and stripped from the flue gas, allowing carbon dioxide gas to be efficiently separated and recovered from a large amount of flue gas. The number of towers filled with gas absorbers may be two or more.

[0075] As described above, in the gas recovery device of the second embodiment, the heat of the exhaust gas is reused to heat the gas absorber, and switching is performed from the state of absorbing acid gas to the state of dissipating it. Therefore, compared with the conventional carbon dioxide gas separation and recovery process, the energy utilization efficiency can be significantly improved. In the second embodiment, if the temperatures of the exhaust gas and absorber cannot be controlled to temperatures suitable for carbon dioxide absorption and dissipation, temperature control can be improved by adding an external heat exchange mechanism or an additional heating mechanism to the piping and absorber. The gas recovery device can also be used for the purpose of supplying gas, and when used for the purpose of supplying gas, it is provided as a gas supply device. [Example]

[0076] The features of the present invention will be explained in more detail below with reference to examples and comparative examples. The materials, amounts used, ratios, treatment details, treatment procedures, etc. shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be interpreted as being limited by the specific examples shown below. In the following explanation, the concentration in parentheses indicates the concentration of the target component in the reaction mixture.

[0077] In this example, the reversible gas absorption test was carried out as follows. (CO2 reversible absorption test) A polymer sample was placed in a reactor, water was added, and the reactor was sealed and placed in a thermostatic chamber at 30°C. Humidified 10% CO2 gas (CO2:N2 = 10:90) at 60°C was introduced into the reactor at a flow rate of 10 mL / min for 46 minutes, allowing the polymer sample to absorb CO2. The temperature inside the thermostatic chamber was then raised to 75°C and maintained for 25 minutes, allowing the CO2 gas to dissipate. The amount of CO2 gas emitted from the reactor was measured and used as the reversible CO2 absorption amount of the polymer. In the following Examples 1 to 6 and Comparative Examples 1 to 8, 20 g of a polymer sample was placed in a 90 mL reactor, and 40 mL of water was added for measurements.

[0078] [1] Examination of the total monomer concentration in the reaction mixture Comparative Example 1: Preparation of polymer with a total monomer concentration of 1.1 mol / L A mixture was prepared by dissolving N-(dimethylaminopropyl)methacrylamide (DMAPM: 5842.98 mg (6215.94 mL), 55 mol%), N,N'-methylenebisacrylamide (BIS: 962.02 mg, 10 mol%), and cetyltrimethylammonium bromide (CTAB: 36.445 mg, 2 mM) in MilliQ water to a total volume of 50 mL. This mixture was heated to 70 °C while stirring with a mechanical stirrer, and then a solution of N-tert-butylacrylamide (TBAm: 2779.80 mg, 35 mol%) dissolved in methanol (5 mL) was added and nitrogen bubbling was performed for 30 minutes. To this mixture was added an acetone solution (250 μL) containing 2,2'-azobis(2-methylpropionitrile) (AIBN: 21.18 mg, 2.58 mM) to form a reaction mixture, which was polymerized at 70°C for 3 hours under a nitrogen atmosphere to obtain a polymer precipitate. This reaction solution was filtered, and the collected polymer was freeze-dried to obtain Comparative Sample 1.

[0079] Comparative Example 2: Preparation of polymer with a total monomer concentration of 0.57 mol / L A freeze-dried polymer (Comparative Sample 2) was obtained in the same manner as in Comparative Example 1, except that the amounts of DMAPM, TBAm, and BIS were changed as shown in Table 1.

[0080] Example 1: Preparation of polymer with a total monomer concentration of 1.7 mol / L A polymer precipitate was obtained in the same manner as in Comparative Example 1, except that the amounts of DMAPM, TBAm, and BIS were changed as shown in Table 1 and TBAm was dissolved in 8 mL of methanol and added to the mixture. 100 mL of MilliQ water was added to the polymer precipitate and the mixture was pulverized with a hand blender to prepare a slurry. The slurry was filtered, and the collected polymer was freeze-dried to obtain Sample 1.

[0081] Example 2: Preparation of polymer with a total monomer concentration of 2.4 mol / L To a flask containing BIS (4625.10 mg, 20 mol%) and CTAB (36.445 mg, 2 mM), DMAPM (14045.63 mg (14942.15 mL), 55 mol%) was added to partially dissolve the BIS, followed by the addition of 30 mL of MilliQ water. The mixture was heated to 70 °C while stirring with a mechanical stirrer, and then a solution of TBAm (4773.00 mg, 25 mol%) in methanol (12 mL) was added. Nitrogen bubbling was performed for 30 minutes. To this mixture, an acetone solution (250 μL) containing AIBN (21.18 mg, 2.58 mM) was added to form a reaction mixture. The reaction mixture was polymerized at 70 °C for 3 hours under a nitrogen atmosphere to obtain a polymer precipitate. The polymer precipitate was immersed in water overnight and then crushed with a hand mixer to obtain a slurry. The slurry was filtered, and the collected polymer was freeze-dried to obtain Sample 2.

[0082] Comparative Example 3: Preparation of polymer with a total monomer concentration of 0.31 mol / L A polymer was synthesized in the same manner as in Synthesis Example 1 of WO 2016 / 024633. Specifically, 1 L of purified water was placed in a three-neck flask and heated to 70°C. 2 mM CTAB was added, followed by a methanol solution containing DMAPM (55 mol%), TBAm (43 mol%), and BIS (2 mol%), dissolved to a total monomer concentration of 0.31 mol / L. The mixture was stirred with a mechanical stirrer while maintaining the temperature at 70°C, and nitrogen was bubbled through for 1 hour. 5 mL of an aqueous solution containing 2,2'-azobis(2-methylpropionamidine) dihydrochloride (700 mg) was added to the reaction mixture, which was then polymerized under a nitrogen atmosphere at 70°C for 3 hours to yield polymer particles with a particle size of 800 nm (Comparative Sample 3).

[0083] The amounts of components in the reaction mixtures used to synthesize the polymers produced in each example and comparative example are shown in Table 1. In Comparative Sample 3 in the table below, 2,2'-azobis(2-methylpropionamidine) dihydrochloride was used as the initiator (see * in the table).

[0084] [Table 1]

[0085] The yield and reversible CO2 absorption amount of Samples 1 and 2 and Comparative Samples 1 to 3 were measured and the results are shown in Table 2. Here, "yield" is the ratio (%) of the actual yield to the theoretical yield of the polymer calculated from the amount of each monomer used in the reaction mixture.

[0086] [Table 2]

[0087] As shown in Table 2, Samples 1 and 2 had excellent CO2 reversible absorption amounts, with Sample 2 being the best. Furthermore, Samples 1 and 2 had significantly improved yields compared to Comparative Sample 3. Samples 1 and 2 and Comparative Samples 1 and 2 had equivalent yields. That is, Sample 2, which had a higher total monomer concentration, achieved a yield equivalent to that of Sample 1 and Comparative Samples 1 and 2, which had lower total monomer concentrations. This demonstrates that the yield can be increased without increasing the size of the production vessel, demonstrating that the production method of the present invention is industrially advantageous. In addition, when water was added to each sample to examine the water content, it was found that the water content was lowest in the order of Sample 2, 1, Comparative Sample 1, 2, and 3. Furthermore, a durability test was conducted on Sample 2, in which the reversible gas absorption test was carried out 50 times. The reversible CO2 absorption amount was the same even after the 50th test as it was after the first test, confirming that the sample has sufficient durability. Furthermore, as a modification of Sample 2, TBAm-free methanol was added to the reaction mixture instead of the TBAm methanol solution, and a polymer sample was produced with a DMAPM ratio of 80 mol %. A CO2 reversible absorption test was performed on this polymer sample, and the CO2 reversible absorption amount was increased compared to Sample 2. Furthermore, the CO2 reversible absorption amount was greater than that of a polymer sample prepared by adding water instead of methanol (a polymer sample produced using a 100% water solvent). As another modification of Sample 2, a polymer sample was prepared using dimethylaminopropylacrylamide (DMAPAAm) instead of DMAPM as the monofunctional monomer, and results equivalent to those of Sample 2 were obtained.

[0088] [2] Examination of the concentration of multifunctional monomers and the effect of surfactants Example 3: Preparation of polymer without surfactant (CTAB) A lyophilized polymer (sample 3) was obtained in the same manner as in Example 1, except that CTAB was not added to the reaction mixture.

[0089] Comparative Example 4: Preparation of a polymer containing 10 mol% of a multifunctional polymer (BIS) A freeze-dried polymer (Comparative Sample 4) was obtained in the same manner as in Example 3, except that the proportion of TBAm was changed to 35 mol % and the proportion of BIS was changed to 10 mol % among the monomers.

[0090] Comparative Example 5: Preparation of a polymer containing 10 mol% of a multifunctional polymer (EGDMA) A freeze-dried polymer (Comparative Sample 5) was obtained in the same manner as in Example 1, except that the proportion of TBAm among the monomers was changed to 35 mol % and ethylene glycol dimethacrylate (EGDMA) was used instead of BIS at a proportion of 10 mol %.

[0091] Table 3 shows the amounts of components in the reaction mixtures used to synthesize the polymers produced in Example 3 and Comparative Examples 4 and 5. In Comparative Sample 5 in the table below, EGDMA was used as the polyfunctional monomer (see * in the table).

[0092] [Table 3]

[0093] When water was added to Sample 1 prepared in Example 1 above, Sample 3 prepared here, and Comparative Samples 4 and 5, Comparative Samples 4 and 5, which contained 10 mol% of a multifunctional monomer (BIS or EGDMA), both had high water contents and swollen and became soft. However, Samples 1 and 3, which contained 20 mol% BIS, had relatively low water contents and remained hard. This indicates that to obtain a polymer with low swelling, it is necessary to use a multifunctional monomer in a proportion of 15 mol% or more. Furthermore, when comparing Sample 1, which contained a surfactant (CTAB), with Sample 3, which did not contain CTAB, only Sample 3 exhibited a slight transparent phase near its surface. This indicates that adding a surfactant to the reaction mixture is preferable to obtain a uniform polymer.

[0094] Comparative Examples 6 to 8: Preparation of polymers containing 0 to 10 mol% of multifunctional polymer (BIS) and a total monomer concentration of 2.4 mol / L Lyophilized polymers (comparative samples 6 to 8) were obtained in the same manner as in Example 2, except that the proportions of TBAm and BIS among the monomers were changed as shown in Table 4.

[0095] Example 4: Preparation of a polymer with a multifunctional polymer (BIS) content of 30 mol % and a total monomer concentration of 2.4 mol / L A freeze-dried polymer (sample 4) was obtained in the same manner as in Example 2, except that the proportions of TBAm and BIS among the monomers were changed as shown in Table 4.

[0096] The amounts of components in the reaction mixtures used to synthesize the polymers of the samples produced in Comparative Examples 6 to 8 and Example 4 are shown in Table 4, along with those of Sample 2 produced in Example 2.

[0097] [Table 4]

[0098] When water was added to Sample 2 (prepared in Example 2), Sample 4 (prepared here), and Comparative Samples 6–8, Comparative Sample 6 (which did not contain a polyfunctional monomer (BIS)) and Comparative Samples 7 and 8 (which contained 5 mol% or 10 mol% BIS) all had high water contents and swollen and became soft. However, Samples 2 and 4 (which contained 20 mol% or 30 mol% BIS) remained hard. Furthermore, the yield and CO2 reversible absorption capacity were similar for Comparative Samples 7 and 8 and Samples 2 and 4 (BIS concentrations: 5–30 mol%). However, when polymer samples with BIS concentrations above 30 mol% were tested, the CO2 reversible absorption capacity tended to decrease. This indicates that to obtain polymers with low water content and swelling, a polyfunctional monomer of 15 mol% or more is required. To fully demonstrate CO2 reversible absorption capacity, polymers must be synthesized using a polyfunctional monomer of 30 mol% or less.

[0099] Here, as a modification of Sample 2, a polymer sample was produced using 20 mol% EGDMA as the polyfunctional monomer instead of BIS, and a CO2 reversible absorption test was performed. The resulting polymer sample exhibited a CO2 reversible absorption capacity equivalent to that of Sample 2. Furthermore, the polymer sample produced using 20 mol% EGDMA had significantly smaller water content and swelling volume than comparative samples with 5 mol% or 10 mol% EGDMA (approximately one-third of that for 10 mol% EGDMA and less than half that for 5 mol% EGDMA), and exhibited a significantly larger CO2 reversible absorption capacity (approximately 1.5 times that for 10 mol% EGDMA and more than twice that for 5 mol% EGDMA).

[0100] [3] Solvent considerations Examples 5 and 6: Preparation of polymer with a total monomer concentration of 3.0 mol / L Lyophilized polymer samples (samples 5 and 6) were obtained in the same manner as in Example 2, except that the amounts of MilliQ water added to the reaction mixture and the amount of methanol used to dissolve TBAm (amount of methanol added to the reaction mixture) were changed as shown in Table 5.

[0101] The amounts of MilliQ water and methanol added to the reaction mixtures in Examples 2, 5, and 6, and the reversible CO2 absorption amounts measured for Samples 2, 5, and 6 are shown in Table 5.

[0102] [Table 5]

[0103] In both Examples 5 and 6, the water content of the polymer was less than 0.7 g (H2O) / 1 g (hydrated polymer), resulting in a low-water, high-quality polymer material. As shown in Table 5, Sample 5, which contained a reduced amount of solvent, exhibited a lower CO2 reversible absorption rate than Sample 2. Furthermore, when the solvent composition was reduced to water only, the CO2 reversible absorption rate further decreased. This suggests that excessively reducing the amount of solvent increases the concentration of low-polarity monomers, such as TBAm, in the polymer during polymerization, resulting in an extremely low-polarity local environment around the amines inside the gel. This, in turn, reduces the basicity of the amines, thereby reducing the CO2 reversible absorption rate. Even if the monomer is liquid, it is necessary to add a certain amount of water, alcohol, or other solvent to the reaction mixture. Furthermore, Sample 5, which used methanol, exhibited a higher CO2 reversible absorption rate than Sample 6, which did not use methanol, demonstrating the preference for using an alcohol, such as methanol, as a solvent. In addition, polymer samples were produced and tested in the same manner as in Examples 2, 5, and 6, except that ethanol, isopropanol, butanol, or t-butanol was used instead of methanol. The results were equivalent to those obtained when methanol was used.

[0104] [4] Preparation of polymers subjected to the amine impregnation process Example 7: Preparation of a polymer using DMAm (a monofunctional monomer having no amino group) as a monofunctional monomer and carrying out an amine impregnation step Dimethylacrylamide (DMAm: 80 mol%), BIS (20 mol%), and CTAB (2 mM) were dissolved in MilliQ water to prepare a 50 mL mixture. The mixture was heated to 70 °C while nitrogen was bubbled through for 30 minutes. To this mixture, nitrogen-bubbled methanol (12 mL) was added, followed by an acetone solution (250 μL) containing AIBN (2.58 mM). Polymerization was carried out under a nitrogen atmosphere at 70 °C for 3 hours to obtain a polymer precipitate. The polymer precipitate was left overnight in water, then crushed with a hand mixer and filtered to recover the polymer (hydrated polymer). The water content of the recovered polymer was 0.6774 g (HO) / g (hydrated polymer). 1 g of the obtained polymer was weighed out, and 2-(isopropylamino)ethanol (IPAE: 7490 μL) was added as an amine-containing treatment solution, and the polymer was immersed in the solution. The amine-containing treatment solution was slowly stirred overnight on a shaker to replace the water contained in the polymer with 8 N IPAE, and then the polymer was filtered to obtain a polymer material (Sample 7) impregnated with IPAE.

[0105] Example 8: Production of a polymer using NiPAm (a monofunctional monomer having no amino group) as a monofunctional monomer and carrying out a step of swelling the polymer with an amine solution A polymer material (sample 8) impregnated with 8N IPAE was obtained in the same manner as in Example 7, except that N-isopropylacrylamide (NiPAm) was used instead of DMAm.

[0106] Example 9: Preparation of a polymer using DMAPM (a monofunctional monomer having an amino group) and TBAm (a monofunctional monomer having a hydrophobic group) as monofunctional monomers, and carrying out a step of swelling the polymer with an amine solution The polymer obtained in the same manner as in Example 2 was left to stand overnight in water, then pulverized with a hand mixer and filtered to recover the hydrous polymer. The water in this polymer was replaced with 8N IPAE in the same manner as in Example 7 to obtain a polymer material (Sample 9) impregnated with 8N IPAE.

[0107] Example 10: Production of a polymer using DMAPM (a monofunctional monomer having an amino group) as a monofunctional monomer and carrying out a step of swelling the polymer with an amine solution A polymer material (sample 10) impregnated with 8N IPAE was obtained in the same manner as in Example 9, except that TBAm-free methanol was added to the reaction mixture instead of the TBAm methanol solution and the proportion of DMAPM was 80 mol %.

[0108] Table 6 shows the amounts of the components in the reaction mixture used to synthesize the polymers produced in Examples 7 to 10.

[0109] [Table 6]

[0110] The reversible CO2 absorption capacity of samples 7 to 10 swollen with an amine solution was significantly increased compared to the CO2 reversible absorption capacity of a polymer sample prepared in the same manner except for swelling with water: approximately three times for samples 7 and 8, approximately five times for sample 9, and approximately two times for sample 10. It was also shown that the reversible gas absorption capacity could be further improved by improving the substitution rate of water and IPAE.

[0111] [5] Seat manufacturing (Example 11) Production of a sheet using a polymer The polymer precipitate synthesized in the same manner as in Example 2 was filtered and pulverized to obtain polymer powder. This polymer powder was mixed with polyethylene pellets in a mass ratio of 1:2 and subjected to twin-screw extrusion molding. The strands were spread to a width of approximately 4 mm using a roller and cut to approximately 5 mm using a pelletizer to produce a sheet of 200 μm, 4 mm wide, and 5 mm long. A reversible gas absorption test was performed on this sheet, and a CO2 reversible absorption capacity of 33 mL / g was obtained. This confirmed that the produced polymer also exhibited reversible gas absorption performance when used as a sheet.

[0112] [6] Examination of polyfunctional monomer concentration and total monomer concentration Comparative Example 9: Preparation of a polymer with a polyfunctional monomer (BIS) content of 5 mol % and a total monomer concentration of 2.3 mol / L Dimethylaminopropylacrylamide (DMAPAAm: 95 mol%) and BIS (5 mol%) were dissolved in MilliQ water at 60°C to a total volume of 30 mL. Ethanol was then added to prepare a mixture so that the total monomer concentration of the reaction mixture used in the subsequent reaction step was 2.3 mol / L. This mixture was then heated to 70°C, and nitrogen bubbling was performed for 30-60 minutes while stirring. A solution prepared by dissolving AIBN in a mixed solvent of acetone and water (AIBN concentration in the reaction mixture: 2.58 mM) was added to this mixture to form a reaction mixture, which was then polymerized at 70°C for 3 hours under a nitrogen stream to obtain a polymer material (Comparative Sample 9).

[0113] (Comparative Example 10, Examples 11 and 12) Preparation of polymers with a polyfunctional monomer (BIS) content of 10 to 30 mol % and a total monomer concentration of 2.3 mol / L Polymer materials (Comparative Sample 10, Samples 11 and 12) were obtained in the same manner as in Comparative Example 8, except that the proportions of DMAPAAm and BIS were changed as shown in Table 7.

[0114] (Examples 13 to 16) Preparation of polymers with a polyfunctional monomer (BIS) content of 20 mol % and a total monomer concentration of 0.54 to 2.3 mol / L Polymer materials (samples 13 to 16) were obtained in the same manner as in Comparative Example 9, except that the ratio of DMAPAAm and BIS was set to DMAPAAm:BIS = 80 mol%:20 mol% and the reaction mixture was prepared so as to have the total monomer concentration shown in Table 7.

[0115] For the samples produced in Comparative Examples 9 and 10 and Examples 11 to 16, the monomer composition and total monomer concentration of the reaction mixture used in polymer synthesis, as well as the water content, swelling volume, and reversible CO2 absorption of the polymer material, are shown in Table 7. In Table 7, "g (wet)" represents the wet polymer weight, "mL (wet)" represents the wet polymer volume, and "g / dry" represents the dry polymer weight in g or mL.

[0116] [Table 7]

[0117] In Table 7, samples 9, 10, 11, and 12 were compared. The total monomer concentration in the reaction mixture was 2.3 mol / L, and the proportion of polyfunctional monomer (BIS) was varied. Samples 11 and 12, which had a BIS proportion greater than 10 mol% and less than 30 mol%, had lower water content and swelling index, and thus higher CO2 reversible absorption per unit volume, than samples 9 and 10, which had a BIS proportion of 10 mol% or less. Furthermore, samples 13–16, which had a polyfunctional monomer proportion of 20 mol% and different total monomer concentrations in the reaction mixture, showed lower water content and swelling index, and higher CO2 reversible absorption per unit volume, as the total monomer concentration in the reaction mixture increased. These results suggest that by maintaining the polyfunctional monomer proportion within a specified range and increasing the polymerization concentration (total monomer concentration in the reaction mixture), a material with a higher CO2 reversible absorption per unit volume can be achieved. These materials have the advantage that they can achieve sufficient reversible CO2 absorption even when used in a relatively small volume, thereby reducing the amount of heat required to raise temperature.

[0118] [7] Consideration of the type of initiator (Example 17) Preparation of polymer using 2,2'-azobis(2,4-dimethylvaleronitrile) (V-65) as initiator DMAPAAm (80 mol%), BIS (20 mol%), and MilliQ water were placed in a 5L separable flask (first reactor) and immersed in a 50°C water bath. Ethanol was added to this mixture, adjusting the volume of the reaction mixture to a total monomer concentration of 3 mol / L and a total volume of 3000 mL. This mixture was stirred at 100 rpm with nitrogen bubbling for 1 hour, and then the first reactor was immersed in a 55°C water bath. The water bath temperature was then lowered to 45°C to reduce the pressure inside the first reactor. V-65 (2.58 mM) was added as an initiator to the mixture, and the mixture was stirred at 240 rpm for 2 minutes to prepare a reaction mixture. This reaction mixture was then transferred to a stainless steel reactor (second reactor) via a tube. The second reactor was immersed in a 55°C water bath and reacted for 3 hours. The reaction mixture was then removed from the water bath and allowed to cool, yielding a polymer material (Sample 17). The water content of sample 17 was 2.5 g (wet) / g (dry), and the reversible CO2 absorption capacity was 69.5 mL / g (dry). V-65 is an initiator that starts reacting at 47°C, and by using it, it was possible to carry out the polymerization reaction at a relatively low temperature (55°C in this case). Also, under similar conditions, it was possible to synthesize polymer materials by carrying out the polymerization reaction in a resin container (plastic bag). Furthermore, it was also possible to carry out the polymerization reaction while pouring the monomer solution (mixture) onto a conveyor.

[0119] [8] Study on the reversible CO2 absorption of crushed polymer materials The polymer materials synthesized in each of the above examples were pulverized using a meat chopper or a Fitzmill, and the amount of reversible CO2 absorption was measured. The results showed that the amount of reversible CO2 absorption was equivalent regardless of the pulverization method.

[0120] [9] Study of the effect of adding fine particles to polymer materials (Examples 18 and 19) Preparation of polymer material containing fine particles A polymer material was obtained in the same manner as in Comparative Example 9, except that the ratio of DMAPAAm to BIS was DMAPAAm:BIS=85 mol %:15 mol %. The water content of this polymer material was 73.7 wt %. This polymer material was crushed in a meat chopper at 1.5-minute (hole diameter 4.8 mm), 1.3-minute (hole diameter 4.0 mm), 1-minute (hole diameter 3.2 mm), 7-minute (hole diameter 2.4 mm), and 3-minute (hole diameter 1.1 mm) successively to obtain various polymer crushed materials with different crushing degrees. Water-repellent silica RY300 (Evonik: AEROSIL RY300, average primary particle diameter: 7 nm, water contact angle: 100° or more) was added to each polymer crushed material in the blending ratio shown in Table 8 to produce a microparticle-containing polymer material. The microparticle-containing polymer material was placed in a 250 mL plastic container and shaken. The surface was then flattened and the height measured. The results are shown in Table 8. Figure 3 shows the particle size distribution of the microparticle-containing polymer material containing 0.50 vol% water-repellent silica RY300. Figure 4 shows the CO2 absorption and CO2 emission measured by pressure swing absorption spectroscopy for a microparticle-containing polymer material (Sample 18) in which 0.50 vol% water-repellent silica RY300 was added to a 7-minute-milled polymer pulverized material, and for a 7-minute-milled polymer pulverized material (Sample 19). In Figures 3 and 4, "3-minute-milled polymer" to "1.5-minute-milled polymer" represent the 3-minute-milled to 1.5-minute-milled polymer pulverized materials, respectively, and "RY300" represents the water-repellent silica RY300. The CO2 reversible absorption performance was evaluated using the pressure swing absorption method as follows: First, the sample (10 L) contained in the reactor was placed in a thermostatic chamber at 40°C and a relative humidity of over 98% and thoroughly humidified. The temperature was then adjusted to 30°C. Next, a humidified CO2 and N2 mixture (CO2 concentration: 10.03% by volume) was introduced into the sample at a flow rate of 1000 mL / min, and the CO2 concentration (A) of the gas emitted from the sample was measured using a multi-gas analyzer (Horiba, Ltd.: VA-3000) (absorption process). Next, the gas introduced into the sample was switched to humidified N2 gas, which was introduced into the sample at a flow rate of 1000 mL / min, and the CO2 concentration (B) of the gas emitted from the sample was measured (emission process). The CO2 reversible absorption performance of the sample was evaluated by taking the integrated value of the difference between the CO2 concentration of the introduced mixed gas and the CO2 concentration (A) measured during the absorption process as the CO2 absorption amount, and the integrated value of the CO2 concentration (B) measured during the diffusion process as the CO2 diffusion amount. When the CO2 absorption amount measured here is shown on a graph, it is sometimes marked with a "-" and shown on the negative side of the vertical axis to distinguish it from the CO2 diffusion amount.

[0121] [Table 8]

[0122] As shown in Table 8, the bulk (loading amount) of the polymer material changed by changing the proportion of water-repellent silica RY300, with the smallest bulk (highest loading amount) being achieved when the water-repellent silica RY300 was 0.50% by volume. Furthermore, as shown in Figure 4, the microparticle-containing polymer material (Sample 18) with this high loading had significantly improved CO2 reversible absorption and CO2 absorption / desorption rates per unit mass compared to the pulverized polymer (Sample 19) that did not contain water-repellent silica RY300. This indicates that the addition of microparticles can increase the loading of the polymer material and improve the reversible CO2 absorption amount and CO2 absorption / desorption rate.

[0123]

[10] Study on the effect of grinding polymer materials containing fine particles (Example 20) Production of a finely ground polymer containing fine particles, which is obtained by further grinding a finely ground polymer material containing fine particles A microparticle-containing polymer material was obtained by mixing the polymer pulverized in Example 18, pulverized at the 1.5-minute mark with water-repellent silica RY300, at a volume ratio of 99.5:0.5. This microparticle-containing polymer material was milled at 230 rpm using 5 mm diameter zirconia beads in a planetary ball mill (Fritsch P-5) to obtain a pulverized microparticle-containing polymer material (microparticle-containing pulverized polymer, Sample 20). Measurement of the particle size distribution of Sample 20 confirmed that the majority of the pulverized material had a particle size of less than 100 μm. Furthermore, the moisture content of Sample 20 was 72.45 wt %, while the moisture content of the polymer pulverized material in Sample 19 was 73.17 wt %, slightly lower than the moisture content of the polymer material used (73.7 wt %).

[0124] The CO2 absorption amount during the absorption process measured by the pressure swing absorption method for Sample 20 and the above Sample 19 is shown in Figure 5. Here, 10 L of gas absorption material was used as the measurement sample, and measurements were performed at a flow rate of 3000 mL / min for the CO2 and N2 mixed gas and N2 gas. Figure 5 shows that the particle-containing polymer pulverized with a bead mill (sample 20) has a significantly improved CO2 absorption rate compared to the particle-containing polymer material not pulverized with a bead mill (sample 18). This shows that increasing the degree of pulverization of the particle-containing polymer material can further improve its reversible CO2 absorption performance.

[0125] The structures of the monomers, surfactants and initiators used in this example are shown below.

[0126] [ka] JPEG0007800954000011.jpg93159 [Industrial Applicability]

[0127] According to the production method of the present invention, a polymer having low water content but a large reversible gas absorption capacity can be efficiently produced. Therefore, by using the polymer of the present invention, a gas absorption material having high reversible CO2 absorption capacity and easy handling can be provided at low cost. Therefore, the present invention has high industrial applicability. [Explanation of symbols]

[0128] 21 Heat exchanger 22, 33 Desulfurizer 23 Gas absorber 24 No. 1 Pipe 25 Second Pipe 26 Third Pipe 26a Circulation Route 26b Branching Route 31 1st heat exchanger 32 Second heat exchanger 34 First Tank 35 Second Tank 36 First Pipe 37 Second Pipe 37a Main Route 37b Route 1 37c Route 2 38, 39 Gas absorber

Claims

1. A gas separation material for separating acidic gases includes an amine-containing polymer material obtained by polymerizing a monomer mixture containing a monofunctional monomer that does not have an amino group and does not form an amide structure and a polyfunctional monomer in an amount of more than 10 mol % and not more than 30 mol %. The polymer is impregnated with an amine having a molecular weight of 61 to 10,000.

2. 2. The gas separation material of claim 1, wherein the acid gas is carbon dioxide.

3. 3. The gas separation material according to claim 1, wherein the amine has a molecular weight of 75 to 1,000.

4. 3. The gas separation material according to claim 1, wherein the amine has a molecular weight of 90 to 500.

5. The gas separation material according to any one of claims 1 to 4, wherein the polyfunctional monomer has two or more polymerizable groups in the molecule.

6. A gas separation material described in any one of claims 1 to 5, wherein the polymerization is carried out in a reaction mixture containing the monofunctional monomer, the polyfunctional monomer, a solvent and an initiator, and the total monomer concentration of the reaction mixture is 0.7 mol / L or more.

7. The gas separation material according to any one of claims 1 to 5, wherein the total monomer concentration of the reaction mixture is 3 mol / L or less.

8. The gas separation material according to any one of claims 1 to 7, wherein the monofunctional monomer has an acryloyl group or a methacryloyl group.

9. The gas separation material according to any one of claims 1 to 8, wherein the polyfunctional monomer is a polyfunctional (meth)acrylamide-based monomer or a polyfunctional (meth)acrylate-based monomer.

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