Copolymer having a hard polyamide block and a soft block comprising polyethylene glycol

Abstract

The present invention relates to a copolymer having a hard polyamide block and a soft block, which contains, based on the total weight of the copolymer: - a soft block between 55% and 90% by weight, of which at least 35% by weight is derived from polyethylene glycol; - a hard polyamide block between 10% and 45% by weight, wherein the average carbon content in the repeating units of the polyamide block is greater than or equal to 7. The present invention also relates to a method for preparing such a copolymer, a diaphragm comprising such a copolymer, and a method for preparing such a diaphragm.

Description

Technical Field

[0001] The present invention relates to copolymers containing rigid polyamide blocks and flexible blocks, processes for preparing such copolymers, and sheets (membranes, films) formed from such copolymers. Background Art

[0002] Greenhouse gas emissions and their impact on global warming have become a major concern. Various technologies have been developed for the recovery of greenhouse effect-causing gases such as carbon dioxide and methane. Among them, polymeric gas separation membranes have been developed due to their lower environmental impact. Gas separation membranes can also be used in a variety of other applications, such as for purifying natural gas or in novel enthalpy heat exchangers.

[0003] WO 2018 / 222255 describes a gas separation process using a membrane comprising a crosslinked mixture of a polyetheramide copolymer and acrylate-capped polyethylene glycol.

[0004] The paper by Scholes et al. (Crosslinked PEG and PEBAX Membranes for Concurrent Permeation of Water and Carbon Dioxide, Membranes, Vol. 6, No. 1, 0001 (2016)) describes membranes of copolymers containing blocks derived from PTMG and polyamide blocks or blocks of crosslinked polyethylene glycol diacrylate.

[0005] The paper by Car et al. (PEG modified poly(amide-b-ethylene oxide) membranes for CO2 separation, Journal of Membrane Science, Vol. 307, pp. 88 - 95 (2008)) describes membranes prepared from a blend of a copolymer containing a polyamide 6 block and a block derived from polyethylene glycol and a polyglycol.

[0006] The paper by Alqaheem et al. (Polymeric Gas-Separation Membranes for Petroleum Refining, International Journal of Polymer Science, Vol. 2017, No. 117, pp. 1 - 19 (2017)) studied various polymeric membranes and their permeability to several gases.

[0007] The paper by Bondar et al. (Gas Transport Properties of Poly(ether-b-amide) Segmented Block Copolymers, Journal of Polymer Science: Part B: Polymer Physics, Vol. 38, No. 15, pp. 2051-2062 (2000)) relates to membranes of copolymers containing polyamide segments and polyether segments.

[0008] In certain applications, it is desirable to use membranes that are highly permeable to water vapor and carbon dioxide but nearly impermeable to molecular oxygen. In enthalpy heat exchangers, the polymer membranes used must be permeable to water vapor while being impermeable to VOCs (volatile organic compounds). Liquid desiccant air conditioning applications may also require the use of membranes permeable to water vapor to dehydrate the air before cooling it.

[0009] Increasing the permeability of the membrane to water vapor and carbon dioxide can be achieved by increasing the hydrophilicity of the polymer. However, the water uptake also increases significantly, which leads to the deterioration of the mechanical properties of the membrane in the water-saturated state.

[0010] Therefore, there is a need to provide polymers that can be used to prepare gas separation membranes having waterproof breathable properties, good permeability to carbon dioxide, and low permeability to molecular oxygen, while conserving sufficient mechanical properties in the wet state. SUMMARY OF THE INVENTION

[0011] The present invention first relates to copolymers containing rigid polyamide segments and flexible segments, which comprise, based on the total weight of the copolymer:

[0012] - From 55% to 90% by weight of flexible segments, at least 35% by weight of which is from polyethylene glycol;

[0013] - From 10% to 45% by weight of rigid polyamide segments, wherein the average carbon content of the repeating units of the polyamide segments is greater than or equal to 7.

[0014] According to certain embodiments, the flexible segments are polyether segments and / or polyether and polyester segments.

[0015] According to certain embodiments, the flexible segments are segments derived from polyethylene glycol.

[0016] According to certain embodiments, the flexible segments include, in addition to segments derived from polyethylene glycol, segments derived from other polyethers (such as polytetrahydrofuran and / or propylene glycol) and / or polyester.

[0017] According to certain embodiments, the average carbon content of the repeating units of the polyamide block is from 8 to 14, preferably from 8 to 12.

[0018] According to certain embodiments, the rigid polyamide block is a block of polyamide 11, polyamide 12, polyamide 6.10, polyamide 6.12, polyamide 10.10, polyamide 10.12, copolyamide 6 / 11, copolyamide 6 / 12, copolyamide 11 / 12, or a mixture or copolymer thereof.

[0019] According to certain embodiments, the copolymer comprises from 56% to 90%, preferably from 57%, from 58%, or from 59% to 90% by weight of flexible blocks, based on the total weight of the copolymer.

[0020] According to certain embodiments, the copolymer comprises from 10% to 44%, preferably from 10% to 43%, or from 10% to 42%, or from 10% to 41% by weight of rigid polyamide blocks, based on the total weight of the copolymer.

[0021] According to certain embodiments, the copolymer comprises from 60% to 90% by weight of flexible blocks and from 10% to 40% by weight of rigid polyamide blocks, based on the total weight of the copolymer.

[0022] According to certain embodiments, the copolymer comprises at least 40% by weight of flexible blocks derived from polyethylene glycol, preferably from 50% to 90% by weight, or from 55% to 90%, or from 56% to 90%, more preferably from 60% to 80% by weight, based on the total weight of the copolymer.

[0023] According to certain embodiments, the copolymer is a copolymer containing a polyamide 11 block and a block derived from polyethylene glycol, a copolymer containing a polyamide 11 block, a block derived from polyethylene glycol, and a block derived from polytetrahydrofuran, a copolymer containing a polyamide 12 block and a block derived from polyethylene glycol, a copolymer containing a polyamide 12 block, a block derived from polyethylene glycol, and a block derived from polytetrahydrofuran, a copolymer containing a copolyamide 6 / 11 block and a block derived from polyethylene glycol, or a copolymer containing a copolyamide 6 / 11 block, a block derived from polyethylene glycol, and a block derived from polytetrahydrofuran.

[0024] According to certain embodiments, the copolymer has an elongation at break in the water-saturated state as follows: greater than or equal to 100%, preferably greater than or equal to 200%, more preferably greater than or equal to 300%.

[0025] According to certain embodiments, the copolymer has a water absorption (water absorption rate) that reaches saturation at 23 °C in the range of 50% to 160% by weight, preferably 50% to 150% by weight, based on the total weight of the copolymer.

[0026] The present invention also relates to a diaphragm comprising the copolymer as described above.

[0027] According to certain embodiments, the diaphragm is waterproof and breathable.

[0028] According to certain embodiments, the diaphragm has a selectivity of greater than or equal to 10, preferably greater than or equal to 12, measured at a temperature of 23 °C and 0% relative humidity, where the selectivity is defined as the ratio of the permeability of the diaphragm to carbon dioxide to its permeability to molecular oxygen.

[0029] According to certain embodiments, the diaphragm has a water vapor transmission rate (MVTR) as follows: at 23 °C, for a relative humidity level of 50% and a diaphragm thickness of 30 μm, at least 800 g / m 2 per 24 hours, preferably at least 900 g / m 2 more preferably at least 1000 g / m 2 even more preferably from 1000 to 5000 g / m 2 .

[0030] According to certain embodiments, the diaphragm has a thickness of from 0.05 to 100 μm, preferably from 0.5 to 50 μm.

[0031] According to certain embodiments, the diaphragm further comprises at least one polymer or oligomer selected from the following: polyolefins such as polyethylene, polypropylene, poly(3-methyl-1-butene), and poly(4-methyl-1-pentene); vinyl polymers such as polystyrene, poly(methyl methacrylate); polysulfone; fluorinated or chlorinated polymers such as poly(vinylidene fluoride), polytetrafluoroethylene, fluorinated ethylene vinyl / tetrafluoroethylene copolymer, polychloroprene; polyamides such as PA6, PA6.6, and PA12; copolymers containing rigid blocks and flexible blocks such as copolymers containing polyamide blocks and polyether blocks; polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene 2,6-naphthalate; polycarbonates such as poly-4,4′-dihydroxydiphenyl-2,2-propane carbonate; polyethers such as polyoxymethylene and polymethylene sulfide; polyphenylene chalcogenides such as polysulfide, polyphenylene ether, and polyphenylene sulfide; polyetheretherketone; polyetherketoneketone; silicones such as polyvinyltrimethylsiloxane, polydimethylsiloxane, perfluoroalkoxy; polyethylene glycol; ethylene-vinyl acetate; ethylene-methyl acrylate; ethylene-(ethylene-butyl acrylate)-maleic anhydride, ethylene-(ethylene-methyl acrylate)-maleic anhydride, ethylene-glycidyl methacrylate-(ethylene-butyl acrylate), ethylene-(ethylene-methyl acrylate)-glycidyl methacrylate, ethylene-(ethylene-vinyl acetate)-maleic anhydride terpolymer; and mixtures thereof.

[0032] The invention also relates to the use of the copolymer as described above for manufacturing a gas separation diaphragm, or a diaphragm for dehumidifying a gas such as air, or an enthalpy heat exchanger diaphragm, or a fabric diaphragm.

[0033] According to certain embodiments, the gas separation diaphragm is a greenhouse gas recovery diaphragm.

[0034] The invention also relates to a process for preparing the copolymer as described above, which comprises the following steps:

[0035] - Synthesizing a rigid polyamide block from a polyamide precursor;

[0036] - Adding a flexible block;

[0037] - Condensing the rigid polyamide block and the flexible block.

[0038] The invention also relates to a process for preparing the copolymer as described above, which involves mixing the flexible block with a polyamide precursor and a chain-limiting diacid.

[0039] The invention also relates to a process for manufacturing the diaphragm as described above, which comprises the following steps:

[0040] - Supplying the copolymer as described above;

[0041] - Dissolve the copolymer in a solvent;

[0042] - Deposit the polymer dissolved in the solvent on a substrate;

[0043] - Evaporate the solvent.

[0044] The present invention also relates to a process for manufacturing a diaphragm as described above, which comprises the following steps:

[0045] - Supply the copolymer as described above;

[0046] - Melt the copolymer;

[0047] - Form a molten copolymer film;

[0048] - Solidify the film.

[0049] The present invention meets the needs expressed above. It more particularly provides a copolymer that can be used to prepare a diaphragm, and the diaphragm has a high permeability to water vapor and to carbon dioxide. In particular, the diaphragm also exhibits a high selectivity for carbon dioxide relative to molecular oxygen, while maintaining good mechanical properties and good durability in the wet state.

[0050] This is achieved by means of a copolymer that comprises a specific proportion of a rigid polyamide block, a flexible block, and a block derived from polyethylene glycol, and wherein the polyamide has repeating units with an average carbon content greater than or equal to a minimum value.

[0051] According to certain specific embodiments, the present invention also has one or preferably several of the following listed advantageous features: waterproof and breathable properties, a high selectivity for water vapor relative to other gases, a good selectivity for carbon dioxide relative to molecular nitrogen, a good selectivity for hydrogen sulfide relative to methane, a good selectivity for VOCs relative to molecular nitrogen. Description of the Drawings

[0052] Figure 1 Shows the tensile curve obtained for PEBA No. 3 described in Example 1 in the transverse direction relative to extrusion. The elongation (in mm) is given on the x-axis, and the stress (in MPa) is given on the y-axis. The black curve represents the tensile curve obtained before the MVTR measurement test, and the gray curve represents the tensile curve obtained after the MVTR measurement test.

[0053] Figure 2 ​​Show the tensile curves obtained for PEBA number 3 described in Example 1 in the longitudinal direction relative to extrusion. The elongation (in mm) is given on the x-axis and the stress (in MPa) is given on the y-axis. The black curve represents the tensile curve obtained before the MVTR measurement test, and the grey curve represents the tensile curve obtained after the MVTR measurement test.

[0054] Figure 3 Show the tensile curves obtained for PEBA number 2 described in Example 1 in the transverse direction relative to extrusion. The elongation (in mm) is given on the x-axis and the stress (in MPa) is given on the y-axis. The black curve represents the tensile curve obtained before the MVTR measurement test, and the grey curve represents the tensile curve obtained after the MVTR measurement test.

[0055] Figure 4 Show the tensile curves obtained for PEBA number 2 described in Example 1 in the longitudinal direction relative to extrusion. The elongation (in mm) is given on the x-axis and the stress (in MPa) is given on the y-axis. The black curve represents the tensile curve obtained before the MVTR measurement test, and the grey curve represents the tensile curve obtained after the MVTR measurement test.

[0056] Figure 5 Show the tensile curves obtained for PEBA number 7 described in Example 1 in the transverse direction relative to extrusion. The elongation (in mm) is given on the x-axis and the stress (in MPa) is given on the y-axis. The black curve represents the tensile curve obtained before the MVTR measurement test, and the grey curve represents the tensile curve obtained after the MVTR measurement test.

[0057] Figure 6 Show the tensile curves obtained for PEBA number 7 described in Example 1 in the longitudinal direction relative to extrusion. The elongation (in mm) is given on the x-axis and the stress (in MPa) is given on the y-axis. The black curve represents the tensile curve obtained before the MVTR measurement test, and the grey curve represents the tensile curve obtained after the MVTR measurement test. Detailed Description

[0058] The present invention will now be described in more detail and in a non-limiting manner in the following description.

[0059] Unless otherwise stated, all percentages are by weight.

[0060] ​​​​The present invention relates to copolymers containing rigid blocks and flexible blocks. These copolymers are thermoplastic elastomer (TPE) polymers, which comprise rigid (or hard, having a rather thermoplastic behavior) blocks and flexible (or soft, having a rather elastomeric behavior) blocks.

[0061] The term "rigid block" means a block having a melting point or glass transition temperature (in the case of an amorphous block) greater than 20 °C. The presence of a melting point can be determined by differential scanning calorimetry according to Standard ISO 11357-3 Plastics - Differential scanning calorimetry (DSC) - Part 3.

[0062] The term "flexible block" means a block having a glass transition temperature (Tg) less than or equal to 0 °C. The glass transition temperature can be determined by differential scanning calorimetry according to Standard ISO 11357-2 Plastics - Differential scanning calorimetry (DSC) - Part 2.

[0063] The rigid blocks of the copolymers according to the invention are polyamide blocks.

[0064] Advantageously, three types of polyamide blocks can be used.

[0065] According to the first type, the polyamide block is derived from the condensation of a dicarboxylic acid (especially those containing from 4 to 36 carbon atoms, preferably those containing from 6 to 18 carbon atoms) and an aliphatic or aromatic diamine (especially those containing from 2 to 20 carbon atoms, preferably those containing from 6 to 14 carbon atoms).

[0066] As examples of dicarboxylic acids, mention may be made of 1,4-cyclohexanedicarboxylic acid, succinic acid, adipic acid, azelaic acid, suberic acid, sebacic acid, dodecanedioic acid, octadecanedioic acid, terephthalic acid, and isophthalic acid, as well as dimerized fatty acids.

[0067] As examples of diamines, mention may be made of tetramethylenediamine, hexamethylenediamine, 1,10-decamethylenediamine, dodecamethylenediamine, trimethylhexamethylenediamine, isomers of bis(4-aminocyclohexyl)methane (BACM), bis(3-methyl-4-aminocyclohexyl)methane (BMACM), and 2,2-bis(3-methyl-4-aminocyclohexyl)propane (BMACP), p-aminodicyclohexylmethane (PACM), isophoronediamine (IPDA), 2,6-bis(aminomethyl)norbornane (BAMN), and piperazine (Pip).

[0068] Advantageously, polyamide blocks PA 4.12, PA 4.14, PA 4.18, PA 6.10, PA 6.12, PA 6.14, PA 6.18, PA 9.12, PA 10.10, PA 10.12, PA 10.14, and PA 10.18 are used. In the notation PA X.Y, X represents the number of carbon atoms derived from the diamine residue and Y represents the number of carbon atoms derived from the diacid residue, as is conventional.

[0069] According to the second type, the polyamide blocks are obtained from the condensation of one or more α,ω-aminocarboxylic acids containing from 7 to 12 carbon atoms and / or one or more lactams in the presence of a dicarboxylic acid containing from 4 to 12 carbon atoms or in the presence of a diamine. Examples of lactams include enantholactam and laurolactam. As examples of α,ω-aminocarboxylic acids, 7-aminoheptanoic acid, 11-aminoundecanoic acid, and 12-aminododecanoic acid may be mentioned.

[0070] Advantageously, the polyamide blocks of the second type are blocks of PA 11 (polyundecanamide) or PA 12 (polydodecanamide). In the notation PA X, X represents the number of carbon atoms derived from the amino acid residue.

[0071] According to the third type, the polyamide blocks are obtained from the condensation of at least one α,ω-aminocarboxylic acid (or lactam), at least one diamine, and at least one dicarboxylic acid.

[0072] In this case, the polyamide PA blocks are prepared by polycondensation as follows:

[0073] - a linear aliphatic or aromatic diamine containing X carbon atoms;

[0074] - a dicarboxylic acid containing Y carbon atoms; and

[0075] - a comonomer {Z} selected from lactams and α,ω-aminocarboxylic acids containing Z carbon atoms and an equimolar mixture of at least one diamine containing X1 carbon atoms and at least one dicarboxylic acid containing Y1 carbon atoms, (X1,Y1) being different from (X,Y),

[0076] - the comonomer {Z} is introduced in the following weight proportions: advantageously up to 50%, preferably up to 20%, even more advantageously up to 10%, relative to the total amount of polyamide-precursor monomers;

[0077] - in the presence of a chain limiter selected from dicarboxylic acids.

[0078] Advantageously, the dicarboxylic acid containing Y carbon atoms is used as the chain limiter and is introduced in a stoichiometric excess relative to the diamine.

[0079] According to a variant of this third type, the polyamide block is obtained from the condensation of at least two α,ω-aminocarboxylic acids having from 6 to 12 carbon atoms or at least two lactams, or from the condensation of a lactam and an aminocarboxylic acid having different numbers of carbon atoms, in the optional presence of a chain limiter. As examples of aliphatic α,ω-aminocarboxylic acids, mention may be made of aminocaproic acid, 7-aminoheptanoic acid, 11-aminoundecanoic acid, and 12-aminododecanoic acid. As examples of lactams, mention may be made of caprolactam, enantholactam, and laurolactam. As examples of aliphatic diamines, mention may be made of hexamethylenediamine, dodecamethylenediamine, and trimethylhexamethylenediamine. As examples of alicyclic diacids, mention may be made of 1,4-cyclohexanedicarboxylic acid. As examples of aliphatic diacids, mention may be made of succinic acid, adipic acid, azelaic acid, suberic acid, sebacic acid, dodecanedioic acid, and dimerized fatty acids. These dimerized fatty acids preferably have a dimer content of at least 98%; preferably they are hydrogenated; they are, for example, products sold by Croda under the brand name Pripol, or products sold by BASF under the brand name Empol, or products sold by Oleon under the brand name Radiacid, and polyoxyalkylene α,ω-diacids. As examples of aromatic diacids, mention may be made of terephthalic acid (T) and isophthalic acid (I). As examples of alicyclic diamines, mention may be made of isomers of bis(4-aminocyclohexyl)methane (BACM), bis(3-methyl-4-aminocyclohexyl)methane (BMACM), and 2,2-bis(3-methyl-4-aminocyclohexyl)propane (BMACP), and p-aminodicyclohexylmethane (PACM). Other commonly used diamines may be isophoronediamine (IPDA), 2,6-bis(aminomethyl)norbornane (BAMN), and piperazine.

[0080] As examples of the polyamide block of the third type, mention may be made of the following:

[0081] -PA 6.6 / 6.10 / 11 / 12, where 6.6 represents the condensation of hexamethylenediamine and adipic acid, 6.10 represents the condensation of hexamethylenediamine and sebacic acid, 11 represents the unit obtained from the condensation of aminoundecanoic acid, and 12 represents the unit obtained from the condensation of laurolactam;

[0082] -PA 6 / 11, where 6 represents the unit obtained from the condensation of caprolactam, and 11 represents the unit obtained from the condensation of aminoundecanoic acid;

[0083] -PA 6 / 12, where 6 represents the unit obtained from the condensation of caprolactam, and 12 represents the unit obtained from the condensation of laurolactam;

[0084] -PA 11 / 12, where 11 represents the condensation unit derived from 11-aminoundecanoic acid and 12 represents the condensation unit derived from laurolactam.

[0085] The notations PA X / Y, PA X / Y / Z, etc. relate to copolyamides in which X, Y, Z, etc. represent the homopolyamide units as described above.

[0086] The repeating units of the polyamide blocks of the copolymers according to the invention have an average carbon content of 7 or more.

[0087] The term "average carbon content of the repeating units" means the average value obtained by weighting the number of carbon atoms in each repeating unit present in the polyamide blocks of the copolymer by the molar ratio of the repeating unit to the total amount of the polyamide blocks. For example, for PA X / Y as defined above, which contains a mol% of PA X and b mol% of PA Y (where a% + b% represents 100 mol% of the polyamide), the average carbon content is (a×X + b×Y) / 100. When the polyamide block contains a single repeating unit (as in the case of block PA X or block PAX.Y as defined above), the average carbon content of the repeating units of the polyamide block is equal to the number of carbon atoms in the repeating unit, provided that the polyamide repeating unit (in a known manner) contains only one amide functional group. In the case of the PA X block, the number of carbon atoms in the repeating unit is X. In the case of the PA X.Y block, the number of carbon atoms in the repeating unit is (X + Y) / 2, since the unit X.Y contains two amide functional groups.

[0088] Advantageously, the polyamide blocks of the copolymers according to the invention comprise or consist of blocks such as polyamide PA 11, PA 12, PA 5.4, PA 5.9, PA 5.10, PA 5.12, PA 5.13, PA 5.14, PA 5.16, PA 5.18, PA 5.36, PA 6.4, PA 6.9, PA 6.10, PA 6.12, PA 6.13, PA 6.14, PA 6.16, PA 6.18, PA 6.36, PA 10.4, PA 10.9, PA 10.10, PA 10.12, PA 10.13, PA 10.14, PA 10.16, PA 10.18, PA 10.36, PA 10.T, PA 12.4, PA 12.9, PA 12.10, PA 12.12, PA 12.13, PA 12.14, PA 12.16, PA 12.18, PA 12.36, PA 12.T, or mixtures or copolymers thereof.

[0089] Particularly preferably, the polyamide block of the copolymer comprises a block as follows, or consists of a block as follows: polyamide PA 11, PA 12, PA 6.10, PA 6.12, PA 10.10, PA 10.12, or copolyamide PA 6 / 11, PA 6 / 12, PA 11 / 12, or a mixture or copolymer thereof.

[0090] Preferably, the average carbon content of the repeating unit of the polyamide block according to the present invention is from 8 to 14, more preferably from 8 to 12. In certain embodiments, the carbon content of the repeating unit is from 7 to 8, or from 8 to 9, or from 9 to 10, or from 10 to 11, or from 11 to 12, or from 12 to 13, or from 13 to 14, or from 14 to 15, or from 15 to 18, or from 18 to 22, or from 22 to 25, or from 25 to 30, or from 30 to 40.

[0091] Advantageously, the flexible block of the copolymer is a polyether block (then the copolymer is a PEBA or a copolymer containing a polyamide block and a polyether block) or a polyether and polyester block. The polyether block is formed by alkylene oxide units.

[0092] The flexible block of the copolymer according to the present invention comprises a block derived from polyethylene glycol (PEG). The mass ratio of the block derived from polyethylene glycol in the copolymer is at least 35%, based on the total weight of the copolymer. Preferably, the copolymer according to the present invention comprises at least 40% by weight of the block derived from PEG, more preferably the copolymer comprises from 50% to 90% by weight of the block derived from PEG, more preferably from from 60% to 80% by weight, based on the total weight of the copolymer. In certain embodiments, the copolymer comprises 35 to 40% by weight, or 40 to 45% by weight, or 45 to 50% by weight, or 50 to 55% by weight, or 55 to 60% by weight, or 60 to 65% by weight, or from 65% to 70% by weight, or from 70% to 75% by weight, or from 75% to 80%, or from 80% to 85%, or from 85% to 90% of the block derived from PEG, based on the total weight of the copolymer.

[0093] In certain embodiments, the flexible block of the copolymer according to the present invention consists of a block derived from PEG.

[0094] Alternatively, the flexible block of the copolymer may contain at least one other block in addition to the block derived from PEG.

[0095] The flexible block of the copolymer may comprise, in addition to the block derived from PEG, one or more other polyethers and / or polyesters and / or polysiloxanes and / or polydimethylsiloxanes (or PDMS) and / or polyolefins and / or polycarbonates. Possible flexible blocks are described, for example, in French patent application FR 2941700A1 (from page 32, line 3 to page 33, line 8, from page 34, line 16 to page 37, line 13, and on page 38, lines 6 to 23).

[0096] Preferably, this other block is a polyether block and / or a polyester block different from the block derived from PEG.

[0097] The copolymer may contain in its chain several types of polyethers different from the block derived from PEG, and the corresponding copolyethers may be block or random copolyethers.

[0098] As polyether blocks different from the block derived from PEG and suitable for the present invention, mention may be made of blocks derived from PPG (polypropylene glycol) (which consists of propylene oxide units), blocks derived from PO3G (polytriethylene glycol) (which consists of polytriethylene glycol ether units), and blocks derived from PTMG (polytetramethylene glycol), also known as polytetrahydrofuran (which consists of tetramethylene glycol units), or any combination thereof. Particularly preferably, the polyether block is a block derived from polypropylene glycol and / or polytetrahydrofuran. As a polyether different from PEG, a block obtained by oxyethylation of bisphenol (such as bisphenol A) can also be used. This latter product is described, in particular, in EP 613919.

[0099] The polyether block may also consist of an ethoxylated primary amine. As an example of an ethoxylated primary amine, mention may be made of products having the following formula:

[0100]

[0101] where m and n are integers between 1 and 20, and x is an integer between 8 and 18. These products are commercially available, for example from CECA under the brand name and from Clariant under the brand name

[0102] The flexible block may comprise a polyoxyalkylene polyether block with NH2 chain ends, and such a block can be obtained by the cyanoacetylation of an aliphatic α,ω-dihydroxylated polyoxyalkylene block (also known as a polyether diol). More particularly, commercial products Jeffamine or Elastamine (such as D400, 2000, ED 2003, XTJ 542, which are commercial products from Huntsman Corporation and are also described in JP 2004 / 346274, JP 2004 / 352794, and EP 1482011).

[0103] The polyether diol block is either used in unmodified form and co - polycondensed with a rigid block having carboxyl end groups, or it is aminated to be converted into a polyether diamine and condensed with a rigid block having carboxyl end groups.

[0104] The copolymers according to the invention include copolymers which contain three, four (or even more) different blocks selected from the blocks described in the present specification, since these blocks at least include polyamide blocks and blocks derived from polyethylene glycol.

[0105] For example, the copolymers according to the invention can be multi - block copolymers (or "triblock" copolymers) containing three different types of blocks, which are obtained by the condensation of several of the blocks described above. The triblock can be, for example, a copolymer containing a polyamide block, a polyester block, and a block derived from PEG, or a copolymer containing a polyamide block and two different polyether blocks (such as a block derived from PEG and a block derived from PTMG).

[0106] In a particularly advantageous manner, the copolymers according to the invention contain the following blocks or are composed of the following blocks: PA11, PA 12, PA 6, those derived from PEG, those derived from PTMG, or any mixture or combination thereof, provided that the average carbon content of the repeating units of the polyamide blocks of the copolymer is greater than or equal to 7, and the copolymer contains at least 35% by weight of the block derived from polyethylene glycol.

[0107] In the context of the present invention, particularly preferred copolymers are copolymers which include the following blocks (or are composed of the following blocks):

[0108] - PA 11 and those derived from PEG;

[0109] - PA 11, those derived from PEG, and those derived from PTMG;

[0110] - PA 12 and those derived from PEG;

[0111] - PA 12, those derived from PEG, and those derived from PTMG;

[0112] - PA 6 / 11 and those derived from PEG;

[0113] - PA 6 / 11, those derived from PEG, and those derived from PTMG;

[0114] - PA 6.10 and those derived from PEG;

[0115] - PA 6.10, those derived from PEG, and those derived from PTMG;

[0116] - PA 6 / 12 and those derived from PEG;

[0117] - PA 6 / 12, those derived from PEG, and those derived from PTMG.

[0118] The number-average molar mass of the rigid polyamide block of the copolymer according to the present invention is preferably from 400 to 20,000 g / mol, more preferably from 500 to 10,000 g / mol, and even more preferably from 600 to 6,000 g / mol. In certain embodiments, the number-average molar mass of the rigid polyamide block in the copolymer is from 400 to 500 g / mol, or from 500 to 1,000 g / mol, or from 1,000 to 1,500 g / mol, or from 1,500 to 2,000 g / mol, or from 2,000 to 2,500 g / mol, or from 2,500 to 3,000 g / mol, or from 3,000 to 3,500 g / mol, or from 3,500 to 4,000 g / mol, or from 4,000 to 5,000 g / mol, or from 5,000 to 6,000 g / mol, or from 6,000 to 7,000 g / mol, or from 7,000 to 8,000 g / mol, or from 8,000 to 9,000 g / mol, or from 9,000 to 10,000 g / mol, or from 10,000 to 11,000 g / mol, or from 11,000 to 12,000 g / mol, or from 12,000 to 13,000 g / mol, or from 13,000 to 14,000 g / mol, or from 14,000 to 15,000 g / mol, or from 15,000 to 16,000 g / mol, or from 16,000 to 17,000 g / mol, or from 17,000 to 18,000 g / mol, or from 18,000 to 19,000 g / mol, or from 19,000 to 20,000 g / mol.

[0119] The number-average molar mass of the flexible block is preferably from 100 to 6000 g / mol, more preferably from 200 to 3000 g / mol. In certain embodiments, the number-average molar mass of the flexible block is from 100 to 200 g / mol, or from 200 to 500 g / mol, or from 500 to 800 g / mol, or from 800 to 1000 g / mol, or from 1000 to 1500 g / mol, or from 1500 to 2000 g / mol, or from 2000 to 2500 g / mol, or from 2500 to 3000 g / mol, or from 3000 to 3500 g / mol, or from 3500 to 4000 g / mol, or from 4000 to 4500 g / mol, or from 4500 to 5000 g / mol, or from 5000 to 5500 g / mol, or from 5500 to 6000 g / mol.

[0120] The number-average molar mass is set by the content of the chain limiter. It can be calculated according to the following equation:

[0121] M n = n 单体 ×MW 重复单元 / n 链限制剂 + MW 链限制剂

[0122] In this formula, n 单体 represents the number of moles of the monomer, n 链限制剂 represents the number of moles of the excess limiter (such as diacid), MW 重复单元 represents the molar mass of the repeating unit, and MW 链限制剂 represents the molar mass of the excess limiter (such as diacid).

[0123] The number-average molar masses of the rigid block and the flexible block can be measured by gel permeation chromatography (GPC) before the copolymerization of the blocks. The number-average molar mass of the polyol block can be determined by measuring the hydroxyl value.

[0124] The copolymer according to the present invention can be a linear or branched copolymer. For example, the copolymer can be the following branched copolymer: in which the branching is achieved by the polyol residue of the polyol having a functionality greater than 2 (i.e., the polyol includes at least three hydroxyl groups) binding to the polyamide rigid block of the copolymer.

[0125] The copolymer according to the invention comprises from 55% to 90% by weight of a flexible block and from 10% to 45% by weight of a rigid polyamide block, relative to the total weight of the copolymer. The mass ratio of the flexible block and the rigid block in the copolymer can be determined by DSC (differential scanning calorimetry). Advantageously, the copolymer comprises from 60% to 90% by weight of a flexible block and from 10% to 40% by weight of a rigid polyamide block, relative to the total weight of the copolymer.

[0126] The copolymer may comprise, relative to the total weight of the copolymer, from 55% to 60% by weight of a flexible block and from 40% to 45% by weight of a rigid polyamide block; or from 60% to 65% by weight of a flexible block and from 35% to 40% by weight of a rigid polyamide block; or from 65% to 70% by weight of a flexible block and from 30% to 35% by weight of a rigid polyamide block; or from 70% to 75% by weight of a flexible block and from 25% to 30% by weight of a rigid polyamide block; or from 75% to 80% by weight of a flexible block and from 20% to 25% by weight of a rigid polyamide block; or from 80% to 85% by weight of a flexible block and from 15% to 20% by weight of a rigid polyamide block; or from 85% to 90% by weight of a flexible block and from 10% to 15% by weight of a rigid polyamide block.

[0127] In certain embodiments, the copolymer consists essentially of or consists of a flexible block and a rigid block polyamide in the proportions as indicated above.

[0128] Advantageously, the copolymer according to the invention has an elongation at break greater than or equal to 100% in the water-saturated state (i.e., under water saturation). Preferably, the copolymer has an elongation at break in the water-saturated state as follows: greater than or equal to 150%, more preferably greater than or equal to 200%, even more preferably greater than or equal to 250%, even more preferably greater than or equal to 300%, even more preferably greater than or equal to 350%. The elongation at break in the water-saturated state can be measured according to standard ISO 527 1 BA:2012.

[0129] The term "water-saturated state" or "having water saturation" means the state in which the water absorption of the copolymer is maximum (the copolymer cannot absorb additional water). This water-saturated state can be achieved by immersing a sample of the copolymer in water and measuring the mass of the sample regularly: the water-saturated state is reached when the mass of the sample is stable (it no longer changes).

[0130] Preferably, the copolymer according to the present invention has an elongation at break in the dry state as follows: greater than or equal to 400%, preferably greater than or equal to 450%, more preferably greater than or equal to 500%, even more preferably greater than or equal to 550%, even more preferably greater than or equal to 600%. The elongation at break in the dry state can be measured according to standard ISO 527 1BA:2012.

[0131] The copolymer according to the present invention preferably has a tensile stress in the water-saturated state as follows: greater than or equal to 1 MPa, preferably greater than or equal to 2 MPa, more preferably greater than or equal to 3 MPa, even more preferably greater than or equal to 4 MPa. The tensile stress in the water-saturated state can be measured according to standard ISO 527 1 BA:2012.

[0132] [[ID=⑥]]The copolymer according to the present invention preferably has a tensile stress in the dry state as follows: greater than or equal to 10 MPa, preferably greater than or equal to 12 MPa, more preferably greater than or equal to 15 MPa. The tensile stress in the dry state can be measured according to standard ISO 527 1 BA:2012.

[0133] Advantageously, the copolymer according to the present invention has a water absorption to saturation at 23 °C as follows: from 50% to 160% by weight, based on the weight of the copolymer, preferably from 50% to 150% by weight, for example from 50% to 100% by weight, or 100% to 125% by weight, or 125% to 150% by weight, or 150% to 160% by weight. The water absorption to saturation of the copolymer at 23 °C can be determined according to standard ISO 62:2008.

[0134] Synthesis of the copolymer

[0135] The present invention also relates to a process for preparing the copolymer as described above.

[0136] In a general and known manner, a polymer containing a rigid polyamide block and a flexible block can be prepared according to a "two-step" preparation process (which includes a first step of synthesizing the polyamide block and a second step of condensing the polyamide block and the flexible block) or by a "one-step" preparation process.

[0137] In certain embodiments, the copolymer is prepared according to a two-step process. This process includes the following steps:

[0138] - Synthesizing the rigid polyamide block from a polyamide precursor;

[0139] - Adding the flexible block;

[0140] - Condensing the rigid polyamide block and the flexible block.

[0141] Alternatively, the copolymers according to the invention can be prepared according to a one-step process which involves mixing the flexible block with a polyamide precursor and a chain-limiting diacid.

[0142] General methods for the two-step preparation (i.e., a first step of synthesizing the polyamide block and then a second step of condensing the polyamide and polyether blocks) of copolymers containing polyamide blocks and polyether blocks (also known as PEBA, or polyether-block-amide according to IUPAC) which bear an ester bond between the PA block and the PE block are known and described, for example, in FR2846332. General methods for the preparation of PEBA copolymers which bear an amide bond between the PA block and the PE block are known and described, for example, in EP 1482011. The polyether block can also be mixed with a polyamide precursor and a chain-limiting diacid to prepare a polymer containing polyamide blocks and polyether blocks with randomly distributed units (one-step process).

[0143] Regardless of the preparation method (in one or two steps), the copolymers with polyamide rigid blocks and flexible blocks are obtained by the polycondensation of: a polyamide block with reactive ends and a flexible block with reactive ends, such as in particular the polycondensation of:

[0144] 1) a polyamide block with diamine chain ends and a flexible block with dicarboxylic acid chain ends;

[0145] 2) a polyamide block with dicarboxylic acid chain ends and a flexible block with diamine chain ends (which is obtained, for example, by the cyanoethylation and hydrogenation of an aliphatic α,ω-dihydroxylated polyoxyalkylene block (also known as a polyether diol));

[0146] 3) a polyamide block with dicarboxylic acid chain ends and a polyether diol, the product obtained (in this particular case) being a polyether ester amide.

[0147] The polyamide block with dicarboxylic acid chain ends is derived, for example, from the condensation of a polyamide precursor in the presence of a chain-limiting dicarboxylic acid. The polyamide block with diamine chain ends is derived, for example, from the condensation of a polyamide precursor in the presence of a chain-limiting diamine.

[0148] When the copolymer is a branched copolymer, it can be prepared as follows: during its synthesis, one or more polyols comprising at least three hydroxyl groups are added as branching agents. In the one-step or two-step processes described above, the polyol is added together with the polyamide precursor. Advantageously, the polyol is added in an amount ranging from 0.01% to 10% by weight, preferably from 0.01% to 5% by weight, more preferably from 0.05% to 0.5% by weight, based on the total weight of the polyol, polyamide precursor, and flexible block. Adding a polyol comprising at least three hydroxyl groups produces bridging bonds that link together the rigid polyamide blocks of the copolymer (preferably via ester bonds). The polyol can in particular be:

[0149] - monomeric polyols, especially monomeric aliphatic triols such as glycerol, trimethylolpropane, pentaerythritol, and / or

[0150] - polymeric polyols, especially triols containing polyether chains, polycaprolactone triols, mixed polyether-polyester polyols comprising at least three hydroxyl groups.

[0151] Advantageously, the polyol is selected from: pentaerythritol, trimethylolpropane, trimethylolethane, hexanetriol, diglycerol, methyl glucoside, pentaerythritol dipentaerythritol, cyclodextrin, polyether polyols comprising at least three hydroxyl groups, and mixtures thereof. Preferably, the weight-average molar mass of the polyol is not greater than 3000 g / mol, more preferably not greater than 2000 g / mol.

[0152] Membrane

[0153] The present invention also relates to a membrane (or film) comprising the copolymer as described above.

[0154] Preferably, the thickness of the membrane according to the present invention is from 0.05 to 100 μm. Particularly preferably, the thickness is from 0.5 to 50 μm. The thickness of the membrane can be from 0.05 to 0.5 μm, or from 0.5 to 1 μm, or from 1 to 2 μm, or from 2 to 5 μm, or from 5 to 10 μm, or from 10 to 20 μm, or from 20 to 30 μm, or from 30 to 40 μm, or from 40 to 50 μm, or from 50 to 60 μm, or from 60 to 70 μm, or from 70 to 80 μm, or from 80 to 90 μm, or from 90 to 100 μm.

[0155] In certain embodiments, the membrane consists essentially of or consists of the copolymer as described above.

[0156] In other embodiments, the diaphragm according to the present invention further comprises at least one additional polymer or oligomer selected from the following: polyolefins such as polyethylene, polypropylene, poly(3-methyl-1-butene), and poly(4-methyl-1-pentene); vinyl polymers such as polystyrene, poly(methyl methacrylate); polysulfones; fluorinated or chlorinated polymers such as poly(vinylidene fluoride), polytetrafluoroethylene, vinylidene fluoride / tetrafluoroethylene copolymer, polychloroprene; polyamides such as PA 6, PA6.6, and PA 12; copolymers containing rigid blocks and flexible blocks such as copolymers containing polyamide blocks and polyether blocks; polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene 2,6-naphthalate; polycarbonates such as poly-4,4′-dihydroxydiphenyl-2,2-propane carbonate; polyethers such as polyoxymethylene and polymethylene sulfide; polyphenylene chalcogenides such as polysulfide, polyphenylene ether, and polyphenylene sulfide; polyetheretherketone; polyetherketoneketone; silicones such as polyvinyltrimethylsiloxane, polydimethylsiloxane; perfluoroalkoxy; polyethylene glycol; ethylene-vinyl acetate (EVA); ethylene-methyl acrylate (EMA); ethylene-EBA (ethylene-butyl acrylate)-MAH (maleic anhydride), ethylene-EMA-MAH, ethylene-GMA (glycidyl methacrylate)-EBA, ethylene-EMA-GMA, ethylene-EVA-MAH terpolymers; and mixtures thereof.

[0157] Advantageously, the diaphragm comprises at least 50% by weight of a copolymer containing a rigid polyamide block and flexible blocks as described above, and not more than 50% by weight of additional polymers or oligomers, based on the total weight of the diaphragm.

[0158] The diaphragm may further comprise one or more additives selected from the following: UV stabilizers, crosslinking agents, pigments, metal oxides, zeolites, and mixtures thereof, preferably in a mass amount of from 0.01% to 30% by weight, based on the total weight of the diaphragm.

[0159] The diaphragm according to the present invention may be a composite diaphragm, i.e., a diaphragm that comprises at least one polymer layer as described above deposited on at least one porous, microporous or nanoporous support layer (such as non-woven polypropylene or any polymer-type framework).

[0160] Advantageously, the diaphragm is a waterproof and breathable diaphragm. The term "waterproof and breathable" means permeable to water vapor and impermeable to liquid water.

[0161] Preferably, the diaphragm according to the present invention has the following water vapor permeability (MVTR, representing "Moisture Vapor Transmission Rate"): at 23 °C, at 50% relative humidity, for a diaphragm thickness of 30 μm, at least 800 g / m 2 . More preferably, the water vapor permeability MVTR of the diaphragm is: at 23 °C, at 50% relative humidity, for a diaphragm thickness of 30 μm, at least 900 g / m 2 / 24h, more preferably at least 1000 g / m 2 / 24h, even more preferably from 1000 to 5000 g / m 2 / 24h. In particular, the MVTR diaphragm water vapor permeability (at 23 °C, at 50% relative humidity, for a diaphragm thickness of 30 μm) can range from 800 to 900 g / m 2 / 24hr, or from 900 to 1000 g / m 2 / 24hr, or from 1000 to 1200 g / m 2 / 24h, or 1200 to 1500 g / m 2 / 24hr, or from 1500 to 2000 g / m 2 / 24h, or 2000 to 2500 g / m 2 / 24hr, or from 2500 to 3000 g / m 2 / 24h, or 3000 to 3500 g / m 2 / 24h, or 3500 to 4000 g / m 2 / 24hr, or from 4000 to 4500 g / m 2 / 24hr, or from 4500 to 5000 g / m 2 / 24h. The water vapor permeability (MVTR) of the diaphragm (at 23 °C, at 50% relative humidity, for a diaphragm thickness of 30 μm) can be measured according to standard ASTM E96 B.

[0162] Advantageously, the diaphragm according to the present invention can have the following carbon dioxide permeability CO2TR (representing "CO2 transmission rate"): at 23 °C, at 0% relative humidity, greater than or equal to 100000 cm 3 .25mm / m 2 .24h.atm. Preferably, the carbon dioxide permeability of the diaphragm (at 23 °C, at 0% relative humidity) is greater than or equal to 120000 cm 3 .25μm / m 2.24 h atm, more preferably greater than or equal to 150000 cm 3 .25 μm / m 2 .24 h atm, even more preferably greater than or equal to 160000 cm 3 .25 μm / m 2 .24 h atm, even more preferably greater than or equal to 180000 cm 3 .25 μm / m 2 .24 h atm, even more preferably greater than or equal to 200000 cm 3 .25 μm / m 2 .24 h atm. The permeability of the diaphragm to carbon dioxide (at 23 °C, at 0% relative humidity, for a diaphragm thickness of 25 μm) can be determined by the following method: In a permeation chamber, the upper side of the membrane to be tested is flushed with the test gas, and the gas stream diffusing through the membrane in the lower part of the membrane flushed with the carrier gas is analyzed by gas chromatography. The operating parameters are as follows:

[0163] - Test gas: O2 / CO2 gas mixture, ratio 80 / 20 mol%;

[0164] - Permeation instrument equipment: LYSSY GPM 500 coupled with detection equipment;

[0165] - Detection equipment: Gas chromatography equipped with a TCD (thermal conductivity detector), referring to Agilent 4890D;

[0166] - Gas syringe with a stop valve for chromatography (example: EMS syringe, referring to 008110 / 1MR-V-GT);

[0167] - Aluminum surface reducing agent;

[0168] - Cryostat: One high-power (2.4 kW) for LYSSY GPM500, and two low-power (1.8 kW) for the bubbler bath;

[0169] - Test temperature: 23 °C;

[0170] - Relative humidity: 0%.

[0171] Subsequently, the permeability to the gas is calculated by the following formula:

[0172]

[0173] Wherein the "quantity" is the volume of the relevant gas (CO2 in this case) that has passed through the membrane, "e" is the thickness of the membrane, "area" is the area of the membrane, "time" is the duration of flushing with the test gas, and p1 and p2 are the partial pressures on the two sides upstream and downstream of the membrane respectively.

[0174] Advantageously, the diaphragm according to the present invention has (at 23 °C and 0% relative humidity) a permeability to molecular oxygen ("oxygen transmission rate", OTR) of less than or equal to 50,000 cm 3 .25 μm / m 2 .24 h.atm. Preferably, the permeability of the diaphragm to molecular oxygen is (at 23 °C and 0% relative humidity) less than or equal to 40,000 cm 3 .25 μm / m 2 .24 h.atm, more preferably less than or equal to 30,000 cm 3 .25 μm / m 2 .24 h.atm, even more preferably less than or equal to 30,000 cm 3 .25 μm / m 2 .24 h.atm, even more preferably less than or equal to 25,000 cm 3 .25 μm / m 2 .24 h.atm, even more preferably less than or equal to 22,000 cm 3 .25 μm / m 2 .24 h.atm, even more preferably less than or equal to 20,000 cm 3 .25 μm / m 2 .24 h.atm. The permeability of the diaphragm to molecular oxygen (at 23 °C, 0% relative humidity, for a diaphragm thickness of 25 μm) can be determined by the method described above for the permeability to carbon dioxide (except that the relevant gas is O2).

[0175] Advantageously, the diaphragm according to the present invention has a carbon dioxide / molecular oxygen selectivity P greater than or equal to 10 CO2 / P O2 . The carbon dioxide / molecular oxygen selectivity of the diaphragm corresponds to the ratio of the permeability of the diaphragm to carbon dioxide to the permeability of the diaphragm to molecular oxygen measured at a temperature of 23 °C and 0% relative humidity. The permeabilities of the diaphragm to carbon dioxide and molecular oxygen are determined under the same conditions and can be measured as described above. Preferably, the P CO2 / P O2Selectively greater than or equal to 12, more preferably greater than or equal to 13, even more preferably greater than or equal to 14, and even more preferably greater than or equal to 15. In other advantageous embodiments, it is greater than or equal to 16, or 17, or 18.

[0176] The present invention also relates to the use of the copolymer as described above for manufacturing a diaphragm. In certain embodiments, the diaphragm is a gas separation diaphragm, or a diaphragm for dehumidifying a gas such as air, or an enthalpy heat exchanger diaphragm, or a fabric diaphragm. The diaphragm can also be a diaphragm for recovering greenhouse gases (particularly carbon dioxide and / or methane).

[0177] The diaphragm according to the present invention can be prepared in a known manner by any melt process (e.g., by flat film extrusion ("extrusion casting")) or by extrusion coating on a support, or by a solvent process (e.g., by deposition in a solvent / evaporation process ("solvent casting")).

[0178] In particular, the diaphragm can be manufactured by a process comprising the following steps:

[0179] - Providing the copolymer as described above;

[0180] - Dissolving the copolymer in a solvent;

[0181] - Depositing the polymer dissolved in the solvent on a substrate;

[0182] - Evaporating the solvent.

[0183] Alternatively, the diaphragm can be manufactured by a process comprising the following steps:

[0184] - Providing the copolymer as described above;

[0185] - Melting the copolymer;

[0186] - Forming a molten copolymer film;

[0187] - Solidifying the film.

[0188] When the diaphragm is a composite layer, the polymer layer can be deposited on the support layer by extrusion coating, extrusion lamination, adhesive lamination, deposition by solvent / evaporation ("solvent casting"), atomization ("spray coating"), welding, or sealing.

[0189] Examples

[0190] The following examples illustrate the present invention without limiting the present invention.

[0191] Example 1

[0192] Membranes are prepared by flat film extrusion process ("extrusion casting") using various copolymers containing polyamide blocks and flexible blocks with an extruder having the following parameters:

[0193] - Screw diameter: 30 mm;

[0194] - L / D ratio: 25

[0195] - Profile: screw - barrier;

[0196] - Die: T - shaped, 250 μm wide and 300 μm air gap.

[0197] The extrusion temperature is between 180 °C and 230 °C and is varied to accommodate the guard of the copolymer.

[0198] The characteristics of the copolymers and the membranes are given in the following table:

[0199] [Table 1]

[0200]

[0201] The copolymer of Membrane 8 is prepared from PEG diamine blocks.

[0202] Membranes 7 to 10 are according to the present invention, and Membranes 1 to 6 correspond to comparative examples.

[0203] Various properties of these membranes are tested and the results are given below:

[0204] [Table 2]

[0205]

[0206] The water vapor transmission rate MVTR is measured at 23 °C and 50% relative humidity according to standard ASTM E96B.

[0207] The oxygen transmission rate OTR and the carbon dioxide transmission rate CO2TR are measured at 23 °C and 0% relative humidity level according to the method described above in the specification. The values shown are normalized for a 25 - μm membrane.

[0208] P CO2 / P O2 The selectivity is calculated by dividing the permeability CO2TR by the permeability OTR.

[0209] It is observed that the membranes according to the present invention (Membranes 7 to 10) have both high water vapor permeability, high CO2 permeability, and good P CO2 / P O2 selectivity.

[0210] Compared with the diaphragm according to the present invention, diaphragms 1, 2, and 3 have a lower permeability to carbon dioxide. Diaphragm 1 also has a low permeability to water vapor.

[0211] Diaphragms 4 and 5 have a low permeability to water vapor and a low P CO2 / P O2 selectivity.

[0212] Diaphragm 6 has insufficient mechanical properties in the water-saturated state due to its very high water absorption rate. The elongation at break and tensile stress in the water-saturated state show a very significant decrease relative to these characteristics measured in the dry state.

[0213] Several mechanical properties of the following copolymers were also tested: the copolymer containing PA12 block / block derived from PEG (50 / 50) (PEBA No. 2) for preparing diaphragm 2, the copolymer containing PA6 block / block derived from PEG (50 / 50) (PEBA No. 3) for preparing diaphragm 3, and the copolymer containing PA 11 block / block derived from PEG (40 / 60) (PEBA No. 7) for preparing diaphragm 7.

[0214] Membranes with a thickness of 50 μm were prepared from the three PEBA as described above, and tensile tests were performed on these membranes before and after they were subjected to the MVTR measurement test. For the measurements performed after the MVTR measurement test, the membranes were air-dried for a few minutes before the tensile test.

[0215] Samples approximately 7 mm wide and 50 mm long (3 for each product) were cut using a cutting machine (guillotine). The following traction measurements were performed on these samples: According to the standard ASTM-D 882, a traction speed of 200 mm / min and a length (L0) between the clamps of 25 mm were used. The tensile stress and elongation at break were measured. These properties were determined in the longitudinal direction relative to the extrusion direction and in the transverse direction relative to the extrusion direction.

[0216] The results are shown in Figures 1 to 6 .

[0217] For PEBA No. 3, in the transverse direction, after the MVTR measurement test, the elongation at break and tensile stress show a very strong decrease relative to these characteristics measured before the test ( Figure 1 ). In the longitudinal direction, a decrease in the elongation at break and tensile stress was also observed after the MVTR measurement test, although it is less significant compared to that in the transverse direction ( Figure 2 ).

[0218] Therefore, PEBA No. 3 is sensitive to the MVTR measurement test, and its mechanical properties deteriorate after this test.

[0219] For PEBA No. 2, in the transverse direction, the polymer film has an elongation at break similar to that obtained before the MVTR measurement test. Figure 3 ). However, in the longitudinal direction, the elongation at break and tensile stress after the test are lower than those before the test. Figure 4 )

[0220] PEBA No. 2 shows relatively good tolerance in the MVTR measurement test, but its carbon dioxide permeability is too low, as shown above.

[0221] For PEBA No. 7, in the transverse direction, the film has similar mechanical properties before and after the MVTR measurement test, both in terms of tensile stress and elongation at break. Figure 5 ). In the longitudinal direction, the elongation at break measured after the MVTR measurement test decreases relative to the elongation at break measured before the test. Figure 6 )

[0222] PEBA No. 7 shows good tolerance in the MVTR measurement test and maintains its mechanical properties after this test.

[0223] Example 2

[0224] A branched copolymer is prepared according to a two-step process, in which a polyamide block is first synthesized by mixing a polyamide precursor with a branching agent, and then a flexible block derived from PEG is added and condensed with the polyamide block.

[0225] These copolymers have the following characteristics:

[0226] [Table 3]

[0227]

[0228] The mass quantity of the branching agent corresponds to the mass percentage of the branching agent added together with the polyamide precursor during the synthesis of the copolymer relative to the total weight of all copolymer reagents.

[0229] PEBA Nos. 11, 12, 13, and 14 are prepared from PEG diamine blocks.

[0230] In PEBA No. 15, the polyamide block contains 70 mol% of PA6 and 30 mol% of PA11, and thus has an average carbon content of 7.5 repeating units.

[0231] PEBA No. 15 is a copolymer according to the present invention, and PEBA Nos. 11 to 14 correspond to comparative examples.

[0232] Measure the water absorbency (or water absorption rate) of the copolymer when it reaches saturation at 23°C and its mechanical properties in the dry state and the water-saturated state, and present them in the following table:

[0233] [Table 4]

[0234]

[0235] The water absorption rate is measured according to Standard ISO 62:2008. The tensile stress in the dry state and the water-saturated state and the elongation at break in the dry state and the water-saturated state are measured according to Standard ISO 5271BA:2012.

[0236] Copolymers (PEBA Nos. 11 to 14) containing polyamide blocks (which have an average carbon content of repeating units equal to 6) have a very high water absorption rate and thus have very low tensile stress and elongation at break when saturated with water. The diaphragms formed from these copolymers will thus have low durability.

[0237] In contrast, PEBA No. 15 (which contains a polyamide block having an average carbon content of repeating units equal to 7.5) has a high elongation at break and sufficient tensile stress in the water-saturated state.

[0238] The copolymer according to the present invention has both good permeability to water vapor and to carbon dioxide, good P CO2 / P O2 selectivity, and good mechanical properties in the dry state and the wet state.

Claims

1. A greenhouse gas recovery membrane sheet, which consists of the following: A copolymer containing a rigid polyamide block and a flexible block, which contains, based on the total weight of the copolymer: - From 55% to 90% by weight of the flexible block, at least 35% by weight of which is from polyethylene glycol; - From 10% to 45% by weight of the rigid polyamide block, wherein the average carbon content of the repeating units of the polyamide block is greater than or equal to 7.

2. The membrane sheet according to claim 1, wherein the flexible block is a polyether block and / or a polyether and polyester block.

3. The membrane sheet according to claim 1 or 2, wherein the flexible block is a block derived from polyethylene glycol, or the flexible block further contains, in addition to the block derived from polyethylene glycol, blocks derived from other polyethers such as polytetrahydrofuran and / or propylene glycol, and / or polyester.

4. The membrane sheet according to claim 1 or 2, wherein the average carbon content of the repeating units of the polyamide block is from 8 to 14.

5. The membrane sheet according to claim 4, wherein the average carbon content of the repeating units of the polyamide block is from 8 to 12.

6. The membrane sheet according to claim 1 or 2, wherein the rigid polyamide block is a block such as polyamide 11, polyamide 12, polyamide 6.10, polyamide 6.12, polyamide 10.10, polyamide 10.12, copolyamide 6 / 11, copolyamide 6 / 12, copolyamide 11 / 12, or a mixture or copolymer thereof.

7. The membrane sheet according to claim 1 or 2, wherein the copolymer contains from 60% to 90% by weight of the flexible block and from 10% to 40% by weight of the rigid polyamide block, based on the total weight of the copolymer.

8. The membrane sheet according to claim 1 or 2, wherein the copolymer contains at least 40% by weight of the flexible block derived from polyethylene glycol, based on the total weight of the copolymer.

9. The membrane sheet according to claim 8, wherein the copolymer contains from 50% to 90% by weight of the flexible block derived from polyethylene glycol.

10. The membrane sheet according to claim 9, wherein the copolymer contains from 60% to 80% by weight of the flexible block derived from polyethylene glycol.

11. The membrane sheet according to claim 1 or 2, the copolymer is a copolymer containing a polyamide 11 block and a block derived from polyethylene glycol, a copolymer containing a polyamide 11 block, a block derived from polyethylene glycol, and a block derived from polytetrahydrofuran, a copolymer containing a polyamide 12 block and a block derived from polyethylene glycol, a copolymer containing a polyamide 12 block, a block derived from polyethylene glycol, and a block derived from polytetrahydrofuran, a copolymer containing a copolyamide 6 / 11 block and a block derived from polyethylene glycol, or a copolymer containing a copolyamide 6 / 11 block, a block derived from polyethylene glycol, and a block derived from polytetrahydrofuran.

12. The diaphragm as described in claim 1 or 2, wherein the copolymer has an elongation at break in the water-saturated state of greater than or equal to 100%, and / or a water absorbency to saturation in the range of 50% to 160% by weight at 23°C, based on the total weight of the copolymer.

13. The diaphragm as described in claim 12, wherein the copolymer has an elongation at break in the water-saturated state of greater than or equal to 200%.

14. The diaphragm as described in claim 13, wherein the copolymer has an elongation at break in the water-saturated state of greater than or equal to 300%.

15. The diaphragm as described in claim 12, wherein the copolymer has a water absorbency to saturation in the range of 50% to 150% by weight at 23°C.

16. The diaphragm as described in claim 1 or 2, which has a selectivity of greater than or equal to 10 measured at a temperature of 23°C and 0% relative humidity, the selectivity being defined as the ratio of the permeability of the diaphragm to carbon dioxide to the permeability of the diaphragm to molecular oxygen.

17. The diaphragm as described in claim 16, wherein the selectivity is greater than or equal to 12.

18. The diaphragm according to claim 1 or 2, which has the following water vapor permeability MVTR: at 23 °C, for a relative humidity level of 50% and a diaphragm thickness of 30 μm, at least 800 g / m per 24 hours 2 .

19. The diaphragm according to claim 18, wherein the water vapor permeability MVTR is at least 900 g / m per 24 hours 2 .

20. The diaphragm according to claim 19, wherein the water vapor permeability MVTR is at least 1000 g / m per 24 hours 2 .

21. The diaphragm according to claim 20, wherein the water vapor permeability MVTR is from 1000 to 5000 g / m per 24 hours 2 .

22. The diaphragm as described in claim 1 or 2, which has a thickness from 0.05 to 100 μm.

23. The diaphragm as described in claim 22, wherein the thickness is from 0.5 to 50 μm.

24. The diaphragm as described in claim 1, which further comprises one or more additives selected from the following: UV stabilizers, crosslinking agents, pigments, metal oxides, zeolites, and mixtures thereof, in a mass amount from 0.01% to 30% by weight, based on the total weight of the diaphragm.

25. Use of the copolymer as defined in any one of claims 1 to 15 for manufacturing a greenhouse gas recovery diaphragm.

26. A process for manufacturing a diaphragm as described in any one of claims 1 to 24, which comprises the following steps: - Supplying a copolymer as defined in any one of claims 1 to 15; - Dissolving the copolymer in a solvent; - Depositing the polymer dissolved in the solvent on a substrate; - Evaporating the solvent.

27. A process for manufacturing a diaphragm as described in any one of claims 1 to 24, which comprises the following steps: - Supplying a copolymer as defined in any one of claims 1 to 15; - Melting the copolymer; - Forming a molten copolymer film; - Solidifying the film.

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