JP6722296B2 - Forward osmosis membrane and its application - Google Patents

Description

The present invention relates to a forward osmosis membrane and its use.

The semipermeable membrane is useful for selectively separating a predetermined component from a liquid mixture or a gas mixture, and is suitably used, for example, in producing high-purity water or separating a specific solute from a solution.

Among the reverse osmosis method and the normal osmosis method, which are membrane separation methods using a semipermeable membrane, the reverse osmosis method, which is the conventional mainstream, exposes the reverse osmosis membrane to high pressure. Therefore, as a reverse osmosis membrane, in order to obtain high strength, a porous support (eg, nonwoven fabric), a porous polymer layer (eg, polysulfone layer), and a layer actually functioning as a semipermeable membrane (skin layer, separation layer). (Also referred to as etc.) is mainly used in a composite semipermeable membrane formed by stacking these in this order.

On the other hand, in the forward osmosis method, if a reverse osmosis membrane designed to withstand high pressure is used as it is as a forward osmosis membrane that does not require the pressure resistance of the reverse osmosis membrane, pressure loss will occur and sufficient permeation will occur. No flux is obtained. For example, in U.S. Pat. No. 6,037,037 (page 2), membranes designed for osmosis often have their thick and dense support layers (which must withstand high pressure in reverse osmosis and forward osmosis). The effective support layer for the forward osmosis membrane should be as thin and highly porous as possible because it is not applicable to the forward osmosis method due to reduced water flux and high salt leakage in the method). , And that it should provide a direct passage from the driving solution to the active surface of the membrane.

In the forward osmosis method, the driving force when water moves from the low concentration side (for example, fresh water) to the high concentration side (for example, seawater) is the osmotic pressure generated between the aqueous solutions having different concentrations separated by the forward osmosis membrane. is there. When the thickness of the porous support layer or the porous polymer layer is large, or when the concentration polarization around or inside the forward osmosis membrane is large, the difference in concentration between the two solutions is substantially in the vicinity of the skin layer. As a result, the osmotic pressure is reduced, the driving force is reduced, and the permeation flux is reduced. Patent Document 2 (particularly, the scope of claims and effects of the invention) discloses a forward osmosis membrane having a nonwoven fabric, a polymer layer formed thereon, and a polyamide-based dense layer formed thereon. In this forward osmosis membrane, the concentration polarization in the membrane due to the thick thickness of the non-woven fabric and polymer layer serving as a support is reduced by applying a thin non-woven fabric made of long fibers and a thin polymer layer. Improve the permeation flux in the forward osmosis method.

Further, in Patent Document 3, a composite semipermeable membrane composed of a fibrous support layer, a microporous support membrane and a crosslinked polyamide thin film layer, which can also be used as a forward osmosis membrane for concentration difference power generation, has a microporous support. By forming the membrane from a composition that also contains an aromatic polyether having a sulfonic acid group (for example, an aromatic polyether ketone having an SO ₃ Na group) together with a conventional polysulfone, a high salt rejection rate and a high salt rejection rate are obtained. It is described that water permeability can be realized.

International publication WO2013/186297 (Japanese Patent Publication No. 2015-521534) JP, 2014-213262, A JP, 2014-533, A

However, the conventional forward osmosis membrane has room for further improvement in that it exhibits high water permeability and high salt rejection.

Further, the skin layer in the conventional composite semipermeable membrane cannot be manufactured as a self-supporting membrane, but is formed by applying a membrane forming material on a porous substrate. In order to express high water permeability, it is desirable that the forward osmosis membrane or the skin layer is thin, but in the conventional method, the applied film forming material penetrates into the base material or the unevenness of the non-woven fabric or the like affects. Therefore, it is difficult to manufacture a thin skin layer having no defects.

As a result of intensive studies by the present inventors, a semipermeable membrane using a specific aromatic polyether resin having a protonic acid group as a raw material can be produced as a self-supporting membrane, and this semipermeable membrane and a specific porous substrate are manufactured. It was found that a normal osmosis membrane having a high water permeability and a high salt rejection rate can be produced by stacking and, and thus completed the present invention. The gist of the present invention is as follows.

[1]
A forward osmosis membrane comprising a semipermeable membrane and a porous substrate disposed on at least one surface thereof,
The semipermeable membrane comprises a protonic acid group-containing aromatic polyether resin containing a structural unit (1) represented by the following formula (1) and a structural unit (2) represented by the following formula (2). ,
The porous substrate is a normal osmosis membrane having an air permeability of 100 to 400 cm ³ /cm ² /s and a thickness of 50 to 700 μm, which is measured by the A method (Flagille type method) described in JIS L1096.

［式（１）および（２）において、
Ｒ¹〜Ｒ¹⁰は、それぞれ独立して、Ｈ、Ｃｌ、Ｆ、ＣＦ₃またはＣ_mＨ_2m+1（ｍは１〜１０の整数を示す。）であり、
Ｒ¹〜Ｒ¹⁰の少なくとも１つはＣ_mＨ_2m+1（ｍは１〜１０の整数を示す。）であり、
Ｒ¹〜Ｒ¹⁰は、それぞれ芳香環に２つ以上存在してもよく、１つの芳香環にＣ_mＨ_2m+1が２つ以上存在する場合には、各Ｃ_mＨ_2m+1は互いに同一であっても異なっていてもよい。

[In formulas (1) and (2),
R ^{1 to} R ¹⁰ are each independently H, Cl, F, CF ₃ or C _m H _2m+1 (m represents an integer of 1 to 10),
At least one of R ^{1 to} R ¹⁰ is C _m H _2m+1 (m represents an integer of 1 to 10),
R ^{1 to} R ¹⁰ may be present in two or more in each aromatic ring, and when two or more C _m H _2m+1 are present in one aromatic ring, each C _m H _2m+1 is mutually present. It may be the same or different.

X ^{1 to} X ⁵ are each independently H, Cl, F, CF ₃ or a protonic acid group,
At least one of X ^{1 to} X ⁵ is a protonic acid group,
X ^{1 to} X ⁵ may be present in two or more in each aromatic ring, and when two or more protic acid groups are present in one aromatic ring, the protic acid groups may be the same or different. May be.

A ^{1 to} A ⁶ are each independently a direct bond, —CH ₂ —, —C(CH ₃ ) ₂ —, —C(CF ₃ ) ₂ —, —O— or —CO—.

i, j, k and l each independently represent 0 or 1. ]
[2]
When the molar fractions of the structural unit (1) and the structural unit (2) with respect to the total amount of the structural unit (1) and the structural unit (2) are p and q, respectively, p/q=10/90 to The forward osmosis membrane according to the above [1], which is 70/30.

[3]
The forward osmosis membrane according to the above [1] or [2], wherein the weight average molecular weight of the protonic acid group-containing aromatic polyether resin is 70,000 or more.

[4]
The normal osmosis membrane according to any one of [1] to [3] above, wherein the semipermeable membrane has a thickness of 3 μm or less.

[5]
The forward osmosis membrane according to any one of the above [1] to [4], wherein the tensile rupture strength and the elongation are 40 MPa or more and 40% or more, respectively.

[6]
The forward osmosis membrane according to any one of [1] to [5] above, which has the semipermeable membrane and the porous base material arranged on both surfaces thereof.

[7]
A normal osmosis membrane element comprising the normal osmosis membrane and the spacer according to any of [1] to [6] above.

[8]
A forward osmosis membrane module comprising the forward osmosis membrane element described in [7] above in a container.

[9]
The forward osmosis membrane module according to the above [8], and a feed solution is flown on one surface of the forward osmosis membrane of the forward osmosis membrane module, and a draw solution having a higher concentration than the feed solution is flown on the other surface. A system having a driving pump for moving water contained in the feed solution through the forward osmosis membrane to the draw solution.

ADVANTAGE OF THE INVENTION According to this invention, the normal osmosis membrane which can express a high water permeation rate performance is provided, maintaining a high filtration function and a salt rejection.

FIG. 1 is a schematic diagram of an apparatus used for evaluation of separation performance of a forward osmosis membrane in Examples.

Hereinafter, the present invention will be specifically described.

The forward osmosis membrane according to the present invention includes a semipermeable membrane and a porous substrate arranged on at least one surface thereof.

[Semi-permeable membrane]
(Proton acid group-containing aromatic polyether resin)
The semipermeable membrane comprises a protonic acid group-containing aromatic polyether resin. The aromatic acid group-containing aromatic polyether resin contains a structural unit represented by the following formula (1) and a structural unit (2) represented by the following formula (2).

式（１）および（２）において、
ｉ，ｊ，ｋおよびｌは、それぞれ独立して、０または１を示す。

In formulas (1) and (2),
i, j, k and l each independently represent 0 or 1.

R ^{1 to} R ¹⁰ are each independently H, Cl, F, CF ₃ or C _m H _2m+1 (m represents an integer of 1 to 10), and as C _m H _2m+1 , Examples thereof include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group and a hexyl group.

At least one of R ^{1 to} R ¹⁰ is C _m H _2m+1 (m represents an integer of 1 to 10). Specifically, i, j, k and l and R ^{1 to} R ¹⁰ are at least a group represented by C _m H _2m+1 in the structural unit (1) and/or the structural unit (2). Selected to have one. That is, when i, j, k, and l are all 1, at least one of R ^{1 to} R ¹⁰ is C _m H _2m+1 . For example, i=0, j=1, k=0, and l When =1, at least one of R ^{1 to} R ³ , R ^{5 to} R ⁸ and R ¹⁰ is C _m H _2m+1 .

R ^{1 to} R ¹⁰ may be present in two or more in each aromatic ring, and when two or more C _m H _2m+1 are present in one aromatic ring, each C _m H _2m+1 is mutually present. It may be the same or different.

X ^{1 to} X ⁵ are each independently H, Cl, F, CF ₃ or a protonic acid group.

At least one of X ^{1 to} X ⁵ is a protonic acid group. Specifically, i and j and X ^{1 to} X ⁵ are selected such that the structural unit (1) has at least one protonic acid group. That is, when i=1 and j=1, at least one of X ^{1 to} X ⁵ is a protonic acid group, but when j=0, at least one of X ^{1 to} X ³ is a protonic acid group. , I=0 and j=1, at least one of X ^{1 to} X ³ and X ⁵ is a protonic acid group.

X ^{1 to} X ⁵ may be present in two or more in each aromatic ring, and when two or more protic acid groups are present in one aromatic ring, the protic acid groups may be the same or different. May be.

A ^{1 to} A ⁶ are each independently a direct bond, —CH ₂ —, —C(CH ₃ ) ₂ —, —C(CF ₃ ) ₂ —, —O— or —CO—, and A ^{1 to} A ⁶ at least one of to a ⁶ is -CO-.

Lines at both ends of the formulas (1) and (2) indicate bonds with adjacent structural units.

In the present invention, the protonic acid group means a functional group that easily releases a proton or a hydrogen atom thereof substituted by Na or K, and examples thereof include a sulfonic acid group (—SO ₃ H) and a carboxylic acid group. group (-COOH), phosphonic acid group (-PO ₃ H _2), alkyl sulfonic acid group _{(- (CH 2) n SO} 3 H), carboxylic acid group _{(- (CH 2) n COOH} ), alkylphosphonic group _{(- (CH 2) n PO} 3 H 2), hydroxyphenyl group (-C ₆ H ₄ OH) and these terminal hydrogen atoms include those substituted with Na or K. Examples of the protonic acid _{group, -C n H 2n -SO 3 Y} (n is an integer of 0, Y is H, Na or K) are preferred.

Examples of the structural unit (1) include structural units represented by the following formula (1-1) or the following formula (1-2), and in these structures, A ¹ is -CO-. Is preferred,

さらに具体的には下式（１−３）または下式（１−４）で表される構造単位が挙げられる。

More specifically, structural units represented by the following formula (1-3) or the following formula (1-4) can be mentioned.

（式中、Ｚはそれぞれ独立に前記プロトン酸基であり、ｓはそれぞれ独立に０〜３の整数であり、ｔはそれぞれ独立に０〜４の整数であり、両末端の線は隣り合う構造単位との結合を示す。）
また、構造単位（２）の例としては、下式（２−１）または下式（２−２）で表される構造単位が挙げられ、

(In the formula, Z is each independently the protonic acid group, s is each independently an integer of 0 to 3, t is each independently an integer of 0 to 4, and the lines at both ends are adjacent structures. Indicates a bond with a unit.)
Examples of the structural unit (2) include structural units represented by the following formula (2-1) or the following formula (2-2),

さらに具体的には、下式（２−３）または下式（２−４）で表される構造単位が挙げられる。

More specifically, structural units represented by the following formula (2-3) or the following formula (2-4) can be mentioned.

（式中、ｔはそれぞれ独立に０〜４の整数であり、両末端の線は隣り合う構造単位との結合を示す。）
前記構造単位（１）および前記構造単位（２）の合計量に対する前記構造単位（１）および前記構造単位（２）のモル分率をそれぞれｐおよびｑとすると、水透過性の高い半透膜を形成できることから、ｐ／ｑは好ましくは１０／９０以上、より好ましくは２０／８０以上、さらに好ましくは３０／７０以上である。である。また、塩阻止率が高く、かつゲル化しない半透膜を形成できることから、ｐ／ｑは好ましくは９０／１０以下、より好ましくは７０／３０以下、さらに好ましくは６０／４０以下である。

(In the formula, t is each independently an integer of 0 to 4, and the lines at both ends represent a bond with an adjacent structural unit.)
A semipermeable membrane having high water permeability, where p and q are the mole fractions of the structural unit (1) and the structural unit (2) with respect to the total amount of the structural unit (1) and the structural unit (2), respectively. Therefore, p/q is preferably 10/90 or more, more preferably 20/80 or more, still more preferably 30/70 or more. Is. In addition, p/q is preferably 90/10 or less, more preferably 70/30 or less, and further preferably 60/40 or less, since a semipermeable membrane having a high salt rejection rate and not gelling can be formed.

The protonic acid group-containing aromatic polyether resin may further include a structural unit derived from a polyfunctional compound described below.

The protonic acid group-containing aromatic polyether resin may be a crosslinked body or a non-crosslinked body.

The weight average molecular weight (Mw) of the protonic acid group-containing aromatic polyether resin measured by the method adopted in Examples described below is preferably 70,000 or more, more preferably 80,000 or more, and further preferably Is 90,000 or more. When the molecular weight is within the above range, the resulting semipermeable membrane has high mechanical properties and is difficult to break during film formation or during use. The weight average molecular weight is 180,000 or less from the viewpoint of gel generation rate.

The weight average molecular weight can be controlled by adjusting the molar ratio of the raw material monomers and the amount of the end capping agent when producing the protonic acid group-containing aromatic polyether resin.

The protonic acid group equivalent of the protonic acid group-containing aromatic polyether resin, that is, the mass of the protonic acid group-containing aromatic polyether resin per 1 mol of the protonic acid group was not dissolved in water or methanol and swelling was suppressed. Since it is possible to obtain a semipermeable membrane having a small amount of electrolyte permeation through the membrane, it is preferably 200 g/mol or more. Further, it is preferably 5000 g/mol or less, more preferably 1000 g/mol or less, since a semipermeable membrane having a large water permeation flux and high economy can be obtained.

(Method for producing a protonic acid group-containing aromatic polyether resin)
The protic acid group-containing aromatic polyether resin can be obtained by condensation of a monomer having an aromatic ring according to a conventionally known method (for example, the method described in WO2003/33566). For example, the following formulas (1a) and (2a)

で表されるハロゲン置換基を有する単量体と、下式（１ｂ）および（２ｂ）：

And a monomer having a halogen substituent represented by the following formulas (1b) and (2b):

で表される水酸基を有する単量体との縮合重合によって、前記樹脂を得ることができる。

The resin can be obtained by condensation polymerization with a monomer having a hydroxyl group represented by

In the formula, Y is a halogen atom, and the meanings of the other symbols are the same as those of the same symbols used in the above formulas (1) and (2). The halogen atom preferably includes fluorine and chlorine.

It is preferable to use a basic catalyst such as K ₂ CO _{3 for the} condensation.

Examples of the monomer represented by the above formula (1a) (provided that at least one of X ^{1 to} X ² is a protonic acid group) include, for example, 5,5′-carbonylbis(2-fluorobenzenesulfonic acid). Proton acid group-containing aromatic dihalide compounds such as sodium) and 5,5′-carbonylbis(sodium 2-chlorobenzenesulfonate).

Examples of the monomer represented by the above formula (2a) include, for example,
4,4'-difluorobenzophenone, 3,3'-difluorobenzophenone, 4,4'-dichlorobenzophenone, 3,3'-dichlorobenzophenone, 4,4'-difluorobiphenyl, 4,4'-difluorodiphenylmethane, 4, Aromatic dihalide compounds such as 4'-dichlorodiphenylmethane, 4,4'-difluorodiphenyl ether; and 3,3'-dimethyl-4,4'-difluorobenzophenone, 3,3'-diethyl-4,4'-difluorobenzophenone , 3,3',5,5'-tetramethyl-4,4'-difluorobenzophenone, 3,3'-dimethyl-4,4'-dichlorobenzophenone, 3,3',4,4'-tetramethyl- Examples thereof include alkyl group-containing aromatic dihalide compounds such as 5,5′-dichlorobenzophenone.

Examples of the monomer represented by the above formula (2b) (or the monomer represented by the above formula (1b) (however, X ^{3 to} X ⁵ are all hydrogen atoms)) are, for example,
4,4'-dihydroxybiphenyl, 4,4'-dihydroxydiphenylmethane, 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxybenzophenone, 2,2-bis(4-hydroxyphenyl)propane, 1,1,1 ,3,3,3-Hexafluoro-2,2-bis(4-hydroxyphenyl)propane, 1,4-bis(4-hydroxyphenyl)benzene, α,α′-bis(4-hydroxyphenyl)-1 ,4-Dimethylbenzene, α,α′-bis(4-hydroxyphenyl)-1,4-diisopropylbenzene, α,α′-bis(4-hydroxyphenyl)-1,3-diisopropylbenzene, 1,4- Aromatic dihydroxy compounds such as bis(4-hydroxybenzoyl)benzene, 3,3′-difluoro-4,4′-dihydroxybiphenyl; and 3,3′-dimethyl-4,4′-dihydroxybiphenyl, 3,3′ ,5,5'-Tetramethyl-4,4'-dihydroxybiphenyl, 3,3'-dimethyl-4,4'-dihydroxydiphenylmethane, 3,3',5,5'-tetramethyl-4,4'- Dihydroxydiphenylmethane (also known as bis(3,5-dimethyl-4-hydroxyphenyl)methane), 3,3′,5,5′-tetraethyl-4,4′-dihydroxydiphenylmethane, 3,3′-dimethyl-4, 4'-dihydroxydiphenyl ether, 3,3',5,5'-tetramethyl-4,4'-dihydroxydiphenyl ether, 2,2-bis(3-methyl-4-hydroxyphenyl)propane, 2,2-bis( 3-ethyl-4-hydroxyphenyl)propane, 2,2-bis(3,5-dimethyl-4-hydroxyphenyl)propane, α,α′-bis(3-methyl-4-hydroxyphenyl)-1,4 -Diisopropylbenzene, α,α'-bis(3,5-dimethyl-4-hydroxyphenyl)-1,4-diisopropylbenzene, α,α'-bis(3-methyl-4-hydroxyphenyl)-1,3 -Alkyl group-containing aromatic dihydroxy compounds such as diisopropylbenzene and α,α′-bis(3,5-dimethyl-4-hydroxyphenyl)-1,3-diisopropylbenzene.

You may copolymerize a polyfunctional compound with the said monomer in the range which does not impair the solvent solubility of the said protonic acid group containing aromatic polyether resin. By copolymerizing a polyfunctional compound, the protonic acid group-containing aromatic polyether resin can have a slightly crosslinked structure. The polyfunctional compound has three or more hydroxyl groups in one molecule, for example, (2,4-dihydroxyphenyl)(4-hydroxyphenyl)methanone, 4-[1-(4-hydroxyphenyl)-1- Methylethyl]-1,3-benzenediol, 4-[(2,3,5-trimethyl-4-hydroxyphenyl)methyl]-1,3-benzenediol, 4-[(4-hydroxyphenyl)methyl]- 1,2,3-benzenetriol, (4-hydroxyphenyl)(2,3,4-trihydroxyphenyl)methanone, 4-[(3,5-dimethyl-4-hydroxyphenyl)methyl]-1,2, 3-benzenetriol, 4-[(2,3,5-trimethyl-4-hydroxyphenyl)methyl]-1,2,3-benzenetriol, 4,4'-[1,4-phenylenebis(1-methyl) Ethylidene)]bis[benzene-1,2-diol],5,5'-[1,4-phenylenebis(1-methylethylidene)]bis[benzene-1,2,3-triol], α,α, α'-Tris(4-hydroxyphenyl)-1-ethyl-4-isopropylbenzene, phloroglucin, pyrogallol and the like can be mentioned.

The amount of these copolymers is, from the viewpoint of preventing a decrease in solvent solubility of the protonic acid group-containing aromatic polyether resin, a decrease in fluidity during film formation of the resin, and a decrease in elongation rate of the semipermeable membrane, Preferably 0 to 8 mol%/total OH equivalent (that is, in the total amount (100 mol%) of OH groups contained in the monomer of formula (1b), the monomer of formula (2b) and the polyfunctional monomer, 0 to 8 mol% is an OH group derived from a polyfunctional monomer), and more preferably 0 to 5 mol%/total OH equivalent.

(Proton acid group-containing aromatic polyether resin varnish)
The protonic acid group-containing aromatic polyether resin, the molecular structure is basically linear, since the amount is small even if it has a cross-linked structure derived from the polyfunctional compound, Excellent solvent solubility. Therefore, the resin can be in the form of a varnish dissolved in a solvent.

Examples of the solvent are not particularly limited, and alcohols such as water, methanol, ethanol, 1-propanol, 2-propanol and butanol, hydrocarbons such as toluene and xylene, halogenated carbonization such as methyl chloride and methylene chloride. Hydrogens, ethers such as dichloroethyl ether, 1,4-dioxane and tetrahydrofuran, fatty acid esters such as methyl acetate and ethyl acetate, ketones such as acetone and methyl ethyl ketone, and cellosolve such as 2-methoxyethanol and 2-ethoxyethanol. And aprotic polar solvents such as N,N-dimethylacetamide, N-methyl-2-pyrrolidone, dimethylsulfoxide and dimethyl carbonate. These can be used alone or in combination of two or more. Among them, lower alcohols (methanol, ethanol, 1-propanol, 2-propanol, t-butyl alcohol, etc.), tetrahydrofuran, N-methyl-2-pyrrolidone and the like are preferable because they are water-soluble, and a mixture of these with water. Solvents are also preferred. The resin concentration in the varnish can be selected depending on the method of using the varnish, but is preferably 1% by weight or more and 80% by weight or less.

(Semi-permeable membrane)
The semipermeable membrane is made of the protonic acid group-containing aromatic polyether resin.

The semipermeable membrane is substantially composed of only the protonic acid group-containing aromatic polyether resin, but a small amount (for example, 1% by mass or less, or 0.1% by mass) of other components so as not to impair the effects of the present invention. Mass% or less).

The thickness of the semipermeable membrane is usually 0.01 to 3.0 μm, preferably 0.01 to 1.5 μm. A forward osmosis membrane using a semipermeable membrane having a thickness within this range has sufficient membrane strength and exhibits a sufficiently large permeation flux of water for practical use. The thickness of the semipermeable membrane can be controlled by the manufacturing conditions of the semipermeable membrane, for example, the temperature and pressure during press molding, the varnish concentration during casting and the coating thickness.

The tensile elastic modulus of the semipermeable membrane is preferably 0.8 to 2.0 GPa, more preferably 1.2 to 1.6 GPa. The tensile rupture strength of the semipermeable membrane is preferably 40 MPa or more, and the upper limit thereof is 100 MPa, for example. The elongation of the semipermeable membrane is preferably 40% or more, and the upper limit thereof is, for example, 200%. These tensile elastic modulus, tensile breaking strength and elongation are those measured under the following conditions.

<Measurement conditions for tensile modulus, tensile breaking strength and elongation>
A test piece of length x width x thickness = 100 mm x 10 mm x 5 µm was prepared and pulled at a speed of 50 mm/min using a tensile tester, and the strength when the test piece was cut (broken) (tensile load value was tested The value obtained by dividing by the cross-sectional area of one piece) and the elongation rate are obtained. The elongation rate is calculated by the following formula.

Elongation rate (%)=100×(L−L ₀ )/L ₀
(L ₀ : Length of test piece before test L: Length of test piece at break)
The tensile elastic modulus is a value obtained by dividing the load at break by the cross-sectional area of the test piece and the amount of strain at break, that is, (L−L ₀ )/L ₀ .

The tensile breaking strength and the elongation rate can be increased, for example, by increasing the molecular weight of the protonic acid group-containing aromatic polyether resin.

The solubility of the semipermeable membrane in dimethyl sulfoxide (hereinafter also referred to as “DMSO”) and water can be evaluated by the following mass reduction rates. The mass reduction rate is preferably less than 2% by mass, more preferably 1.0% by mass or less, and particularly preferably 0.5% by mass or less.

<Measurement rate measurement method>
The semipermeable membrane is left standing at 150° C. for 4 hours in a nitrogen atmosphere to dry, and then weighed. The semipermeable membrane is immersed in DMSO or water and left standing at 25° C. for 24 hours. The semipermeable membrane is taken out from DMSO or water, left to stand in a nitrogen atmosphere at 150° C. for 4 hours to dry, and then weighed. The mass reduction rate is calculated from the following formula based on the mass of the semipermeable membrane before and after the immersion.

Mass reduction rate=(mass before immersion of semipermeable membrane-mass after immersion of semipermeable membrane)/mass before immersion of semipermeable membrane×100
The dissolution amount can be reduced by, for example, crosslinking the protonic acid group-containing aromatic polyether resin, and thus the dissolution amount can be within the above range even if the protonic acid group equivalent is small.

(Method for manufacturing semipermeable membrane)
The semipermeable membrane can be manufactured as a self-supporting membrane from the protonic acid group-containing aromatic polyether resin.

The semipermeable membrane can be easily manufactured by press molding or extrusion molding of the protonic acid group-containing aromatic polyether resin. Further, the film of the protonic acid group-containing aromatic polyether resin may be subjected to a stretching treatment or the like.

The semipermeable membrane can also be manufactured from the above-mentioned varnish by a casting method. That is, a semipermeable membrane can be obtained by applying the varnish on a support and volatilizing and removing the solvent. Furthermore, the semipermeable membrane may be peeled from the support to form a self-supporting membrane.

If an organic solvent or the like during casting remains in the semipermeable membrane, the semipermeable membrane may have reduced mechanical strength and may be easily damaged. Therefore, it is preferable that the semipermeable membrane manufactured by the casting method is sufficiently dried and/or washed with water, an aqueous solution of sulfuric acid, hydrochloric acid or the like.

In addition, in the case where the protonic acid group contained in the protonic acid group-containing aromatic polyether resin used in the production of the semipermeable membrane is one in which a hydrogen atom is substituted with Na or K in a functional group that easily releases a proton. Alternatively, a film of the aromatic acid group-containing aromatic polyether resin may be formed and then the film may be contacted with hydrochloric acid, an aqueous solution of sulfuric acid or the like to replace Na or K contained in the protonic acid group with a hydrogen atom. ..

[Porous substrate]
The air permeability of the porous substrate is 100 to 400 cm ³ /cm ² /s. This air permeability is measured as follows based on the method A (Flagille type method) described in JIS L1096.

A 20 cm×20 cm test piece is attached to the tester, the suction fan and the air holes are adjusted so that the pressure of the inclined barometer becomes 125 Pa, and the pressure indicated by the vertical barometer is measured. From the measured pressure and the type of air holes, find the amount of air that passes through the test piece using the conversion table attached to the tester.

The thickness of the porous substrate is usually 50 to 700 μm, preferably 80 to 600 μm, more preferably 100 to 500 μm.

The forward osmosis membrane of the present invention has such a high air permeability and a thin porous substrate is used, so that concentration polarization occurring inside the porous substrate when the forward osmosis membrane is used is suppressed, Moreover, it is considered that the fluid resistance when water permeates the forward osmosis membrane can be reduced, and as a result, the permeation flux of water through the forward osmosis membrane can be increased. The air permeability and thickness of the porous substrate can be controlled by a conventional method.

As a preferable material forming the porous substrate, synthetic resin and natural fiber can be mentioned.

Examples of the synthetic resin include a thermoplastic resin and a thermosetting resin, and the thermoplastic resin is preferable. Specific examples of the thermoplastic resin include olefin polymers, polyester resins, polyamide resins, polyvinyl chloride, and (meth)acrylic resins. Of these, olefin polymers and polyester resins are preferable, and olefin polymers are particularly preferable.

The olefin-based polymer is specifically a homopolymer or copolymer of α-olefin, or a copolymer of α-olefin and another monomer. Examples of the α-olefin include C2-C8 α-olefins such as ethylene, propylene and 1-butene. The olefin-based polymer includes polypropylene, polyethylene, poly-1-butene, poly-4-methyl-1-pentene, ethylene/propylene copolymer, ethylene/1-butene copolymer, ethylene-4-methyl-1-pentene. Polyolefin resins such as copolymers, propylene/1-butene copolymers, 4-methyl-1-pentene/1-decene copolymers, α-olefins such as ethylene/vinyl alcohol copolymers and other monomers Copolymers are included.

Examples of the polyester resin include polyethylene terephthalate, polybutylene terephthalate and polyethylene naphthalate. Examples of the polyamide resin include nylon 6 and nylon 66.

Examples of natural fibers include vegetable fibers such as cotton and hemp, and animal fibers such as silk and wool. Of these, cotton and silk are preferable.

Examples of the porous base material include cloth base materials such as woven cloth, non-woven cloth, and knitted cloth, foamed sheets, and the like. Among them, cloth base materials are preferable, woven cloth and non-woven cloth are more preferable, and non-woven cloth is particularly preferable.

Examples of the non-woven fabric include long-fiber non-woven fabric by the spunbond method, short-fiber non-woven fabric by the melt blown method, long-fiber non-woven fabric such as flash-spun non-woven fabric, spunlace non-woven fabric, air-laid non-woven fabric, thermal bond non-woven fabric, needle punch non-woven fabric, chemical bond non-woven fabric, etc. However, spunbonded nonwoven fabrics and meltblown nonwoven fabrics are preferred. Of these, spunbonded nonwoven fabrics are preferable, and polyethylene terephthalate or polypropylene spunbonded nonwoven fabrics are particularly preferable.

The non-woven fabric may be a core-sheath type or a side-by-side type composite fiber in which the constituent fibers are composite fibers made of different resins and different resins are arranged on the outer surface side of the fibers. Examples of the composite fiber include polyethylene/polypropylene core-sheath type or side-by-side type composite fiber.

The non-woven fabric may be a laminated non-woven fabric. Examples of the laminated nonwoven fabric include laminated nonwoven fabrics including spunbonded nonwoven fabrics and meltblown nonwoven fabrics, including spunbonded nonwoven fabrics and meltblown nonwoven fabrics laminated (SM), spunbonded nonwoven fabrics, meltblown nonwoven fabrics and spunbonded nonwoven fabrics. Examples thereof include those laminated in order (SMS).

To obtain such a laminated nonwoven fabric, a spunbonded nonwoven fabric and a meltblown nonwoven fabric are laminated and formed integrally. As an example of the method of integrating, spunbonded nonwoven fabric and meltblown nonwoven fabric are overlapped and heated and pressed, hot melt adhesive, a method of adhering the two with an adhesive such as a solvent-based adhesive, on the spunbonded nonwoven fabric A method in which fibers are deposited by the melt blown method and heat fusion is performed can be mentioned.

The nonwoven fabric may be a laminated nonwoven fabric in which a porous film having micropores is sandwiched between the nonwoven fabrics. As the laminated nonwoven fabric having such a form, for example, polypropylene (PP) nonwoven fabric, porous PP film and PP nonwoven fabric (SFS) are laminated in this order, PP nonwoven fabric, porous PP film and rayon PP nonwoven fabric (SFR) There may be mentioned those in which and are laminated in this order.

Basis weight of the nonwoven fabric (basis weight of the laminated nonwoven fabric in the case of a layered nonwoven fabric) is preferably 10 to 80 g / m ^2, more preferably about 20 to 40 g / m ² approximately.

[Normal osmosis membrane]
(Normal osmosis membrane)
The forward osmosis membrane of the present invention comprises the semipermeable membrane and the porous base material arranged on at least one surface thereof, and has a high water permeation rate while maintaining a high filtration function and a salt rejection rate. Performance can be realized.

The forward osmosis membrane according to the present invention may include the porous base material on both surfaces of the semipermeable membrane. With this mode, the strength of the forward osmosis membrane is further improved.

In the forward osmosis membrane according to the present invention, a layer other than the porous substrate is provided on both sides or one side of the semipermeable membrane in the order of semipermeable membrane/layer other than porous substrate/porous substrate. Although it may be contained, it is preferable not to include a layer other than the porous substrate from the viewpoint of obtaining a good permeation flux. A polyamide layer may be included as a layer other than the porous substrate, but the thickness thereof is preferably 100 μm or less.

(Method for manufacturing normal osmosis membrane)
The normal osmosis membrane of the present invention can be produced, for example, by producing the semipermeable membrane as a self-supporting membrane and sandwiching the semipermeable membrane from the both surfaces with the two porous base materials.

The forward osmosis membrane can be specifically manufactured by the following procedure. For example, a dilute solution of the protonic acid group-containing aromatic polyether resin is applied on a base material made of PET or the like so that the thickness after drying becomes a target thickness, and after drying, the formed film is peeled off as a self-supporting film. .. A normal osmosis membrane can be manufactured by sandwiching the self-supporting membrane between two porous base materials such as a nonwoven fabric. When the area of the normal osmosis membrane is large, in order to maintain the distance between the semipermeable membrane and the porous base material, they may be bonded together by using an adhesive to the extent that they do not affect the permeation flow rate. Good.

The forward osmosis membrane of the present invention can also be produced by producing the semipermeable membrane as a self-supporting membrane and laminating it on the porous substrate. At this time, the both may be bonded together using an adhesive.

As described above, it was difficult to control the thickness of the skin layer (semipermeable membrane) in the conventional composite semipermeable membrane, but according to the production method of the present invention, the semipermeable membrane described above is first produced as a self-supporting membrane. The thickness of the semi-permeable membrane is controlled because the forward osmosis membrane is manufactured by laminating this on a porous substrate (nonwoven fabric, etc.) or sandwiching it with two porous substrates (nonwoven fabric, etc.). A forward osmosis membrane which has a high water permeability and a high salt rejection can be easily produced.

[Uses of forward osmosis membrane]
The forward osmosis membrane element according to the present invention includes the forward osmosis membrane and the spacer according to the present invention described above. In other words, the forward osmosis membrane element according to the present invention is a conventional forward osmosis membrane element including a forward osmosis membrane and a spacer, in which the forward osmosis membrane according to the present invention is used as the forward osmosis membrane. As the spacer, a conventionally known spacer used for a forward osmosis membrane element can be used.

The forward osmosis membrane module according to the present invention comprises the forward osmosis membrane element according to the present invention housed in a container. In other words, the forward osmosis membrane module according to the present invention is a conventional forward osmosis membrane element in which a forward osmosis membrane element is housed in a container, in which the forward osmosis membrane element according to the present invention is used as the forward osmosis membrane element. Is. As the container, a conventionally known container used for a forward osmosis membrane module can be used.

The system according to the present invention comprises a forward osmosis membrane module according to the present invention, and a feed solution on one side of the forward osmosis membrane according to the present invention which the forward osmosis membrane module comprises, and a feed solution on the other side of the feed solution rather than the feed solution. A drive pump for flowing a high-concentration draw solution is provided, and the water contained in the feed solution can be moved to the draw solution through the forward osmosis membrane.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto.

The contents of the abbreviations used in the examples and comparative examples are shown below.

(1) Solvent DMSO: Dimethyl sulfoxide NMP: N-Methyl-2-pyrrolidone DMF: N,N-Dimethylformamide (2) Constituent component of aromatic polyether DFBP: 4,4'-difluorobenzophenone DSDFBP: 5,5' -Carbonylbis(sodium 2-fluorobenzenesulfonate)
DCDPS: 4,4'-dichlorodiphenyl sulfone DSDCDPS: 5,5'-sulfonylbis(sodium 2-chlorobenzenesulfonate)
TMBPF: 3,3′,5,5′-tetramethyl-4,4′-dihydroxydiphenylmethane TPPA: α,α,α′-tris(4-hydroxyphenyl)-1-ethyl-4-isopropylbenzene In the examples. The test methods for the various tests are as follows.

-Evaluation of resin (i) Weight average molecular weight (Mw)
The weight average molecular weight (Mw) was calculated|required on condition of the following using the GPC(Gel Permeation Chromatography) method.

(1) Measuring temperature: 40℃
(2) Developing solvent: DMF
(3) Flow rate: 1.0 ml/min
(4) Injection volume: 500 μl
(5) Detector: UV detector
(6) Molecular weight standard substance: standard polystyrene-Evaluation of semipermeable membrane (ii) Film thickness The film thickness was measured using a spectrophotometer (ellipsometry) manufactured by JASCO Corporation. Specifically, when light enters the film having a refractive index n at a certain angle (θ), the reflected light A from the front surface of the film and the reflected light B from the back surface interfere with each other to generate a wavy interference spectrum. The film thickness (d) was calculated from the equation (1) by counting the number (Δm) of peaks (peaks or valleys) of the interference spectrum within a certain wavelength range (λ _{1 to} λ ₂ ).

（iii）引張弾性率、引張破断強度、引張伸び率
引張試験機として島津製作所社製小型卓上引張試験機ＥＺ−Ｓシリーズを用い、上述した方法で引張弾性率、引張破断強度および伸び率を測定した。

(Iii) Tensile Elastic Modulus, Tensile Breaking Strength, Tensile Elongation Ratio As a tensile testing machine, a small tabletop tensile tester EZ-S series manufactured by Shimadzu Corporation is used to measure the tensile elastic modulus, tensile breaking strength and elongation rate by the methods described above. did.

(Iv) Solubility in water The semipermeable membrane was allowed to stand for 4 hours at 150°C under a nitrogen atmosphere to dry, and then weighed. Then, the semipermeable membrane was immersed in water and allowed to stand at 25° C. for 24 hours. The semipermeable membrane was taken out from water, allowed to stand at 150° C. for 4 hours in a nitrogen atmosphere to be dried, and then weighed. The mass reduction rate was calculated from the following formula based on the mass of the semipermeable membrane before and after the immersion.

Mass reduction rate=(mass before immersion of semipermeable membrane-mass after immersion of semipermeable membrane)/mass before immersion of semipermeable membrane×100
The meanings of the symbols in Table 1 are as follows.

◯: Mass reduction rate is less than 1 mass% x: Mass reduction rate is 1 mass% or more-Evaluation of forward osmosis membrane A schematic diagram of the apparatus 10 used for evaluation of the separation performance of the forward osmosis membrane is shown in FIG.

The apparatus 10 includes a feed solution tank 1, a flow path 2, a pump 3, a draw solution tank 11, a flow path 12, a pump 13 and an evaluation cell 21. The feed solution tank 1 is installed on the balance 4, and the draw solution tank 11 is equipped with an electric conductivity meter 15. At the start of the evaluation, 500 g of Milli-Q water having an electric conductivity of 50 μS/cm or less was stored in the feed solution tank 1 as the feed solution FS (Feed Solution), and the draw solution DS was drawn in the draw solution tank 11. As a (Draw Solution), 800 g of a 0.6 M NaCl aqueous solution is stored. The feed solution in the feed solution tank 1 flows through the flow path 2 at a rate of 0.6 L/min by using the pump 3, and the draw solution in the draw solution tank 11 is 0.6 L/min by using the pump 13. Flow through the channel 12 at a velocity. The feed solution flowing in the flow channel 2 and the draw solution flowing in the flow channel 12 are in contact with each other through the normal osmosis membrane 22 having an effective membrane area of 0.0042 m ² inside the evaluation cell 21. Through this, part of the feed solution moves to the draw solution, and part of the salt (NaCl) in the draw solution moves (backflow) to the feed solution.

(V) Water permeation flux (Jw)
The weight reduction amount of the feed solution was measured every 1 minute by the balance 4, and the weight reduction amount per unit area of the forward osmosis membrane was defined as water permeation flux (L/(m ² ·h)). The average values for 30 to 60 minutes after the start of circulation are shown in Tables 2 and 6.

(Vi) Salt rejection rate The change in the electrical conductivity of the draw solution is measured every 1 minute by the electrical conductivity meter 15, and this is converted into the change in the molar concentration of the draw solution, and the unit time and the unit area of the forward osmosis membrane are measured. The change in the molar concentration per unit was defined as the salt rejection (Mol/(m ² ·h)). The average values for 30 to 60 minutes after the start of circulation are shown in Tables 2 and 6.

(Monomer Synthesis Example 1)
A white crystal of DSDFBP represented by the following formula was obtained by the method described in paragraph [0061] of JP-A-2014-533 (Synthesis example 1). The yield was 155.2 g (0.386 mol, yield 70%).

（単量体合成例２）
攪拌器、温度計および冷却管を装備した反応フラスコに、ＤＣＤＰＳ（０．６０ｍｏｌ）と、３０％発煙硫酸１８０ｍｌを装入した後、１１０℃で６時間反応した。これを、１．８ｋｇの氷に排出した。次に、ＮａＣｌ３６０ｇおよび水５００ｍｌを加え、加熱溶解した後放冷し一夜放置した。析出した結晶を濾過した後、水３００ｍｌ、エタノール３５０ｍｌを加えて加熱溶解後放冷し、再結晶を行った。析出した結晶を濾過後、再度水１８０ｍｌとエタノール１８０ｍｌで再結晶し、１００℃で６時間および２００℃で４時間乾燥して、下式で表されるＤＳＤＣＤＰＳの白色結晶を得た。収量は９５．５ｇ（０．１９４ｍｏｌ、収率３２％）であった。

(Monomer Synthesis Example 2)
A reaction flask equipped with a stirrer, a thermometer and a condenser was charged with DCDPS (0.60 mol) and 180 ml of 30% fuming sulfuric acid, and then reacted at 110° C. for 6 hours. It was discharged onto 1.8 kg of ice. Next, 360 g of NaCl and 500 ml of water were added, and the mixture was heated and dissolved, then allowed to cool and left overnight. After filtering the precipitated crystals, 300 ml of water and 350 ml of ethanol were added, and the mixture was heated and dissolved, and then allowed to cool, and recrystallized. The precipitated crystals were filtered, recrystallized again with 180 ml of water and 180 ml of ethanol, and dried at 100°C for 6 hours and at 200°C for 4 hours to obtain white crystals of DSDCDPS represented by the following formula. The yield was 95.5 g (0.194 mol, yield 32%).

（樹脂合成例１）
窒素導入管、温度計、還流冷却器、及び撹拌装置を備えた５つ口反応器に、合成例１で得られたＤＳＤＦＢＰ４０．１ｇ（０．０９５ｍｏｌ）、ＤＦＢＰ６２．２ｇ（０．２８５ｍｏｌ）、ＴＭＢＰＦ９７．４ｇ（０．３８０ｍｏｌ）および炭酸カリウム６５．７ｇ（０．４７５ｍｏｌ）を秤取した。これにＤＭＳＯ７８３．４ｇとトルエン２６１．１ｇを加え、窒素雰囲気下で撹拌し、１３０℃で１２時間加熱し、生成する水を系外に除去した後、トルエンを留去した。

(Resin synthesis example 1)
DSDFBP 40.1 g (0.095 mol) obtained in Synthesis Example 1, DFBP 62.2 g (0.285 mol), and TMBPF97 were placed in a 5-neck reactor equipped with a nitrogen inlet tube, a thermometer, a reflux condenser, and a stirrer. 0.4 g (0.380 mol) and 65.7 g (0.475 mol) of potassium carbonate were weighed out. To this, 783.4 g of DMSO and 261.1 g of toluene were added, and the mixture was stirred under a nitrogen atmosphere and heated at 130° C. for 12 hours to remove produced water outside the system, and then toluene was distilled off.

Subsequently, the reaction was carried out at 160° C. for 12 hours to obtain a viscous polymer solution. 570 g of toluene was added to the obtained solution to dilute it, then the mixture was discharged into 2400 g of methanol, the precipitated polymer powder was filtered, washed, and dried at 150° C. for 4 hours to give 171.6 g of polyetherketone powder (yield 95%). ) (Resin 1) was obtained.

Table 1 shows the results of evaluation of various physical properties.

The resin (1) is used as the structural unit (1).

で表される構造を、前記構造単位（２）として

The structure represented by is as the structural unit (2)

で表される構造を有している。

It has a structure represented by.

(Resin synthesis example 2)
The resin raw material and solvent were DSDFBP 48.1 g (0.114 mol), DFBP 58.0 g (0.265 mol), TMBPF 97.4 g (0.380 mol) and potassium carbonate 65.7 g (0.475 mol), and DMSO 814.4 g and 175.2 g of polymer powder (yield 93%) (resin 2) was obtained in the same manner as in Example 1 except that 271.5 g of toluene was used. Table 1 shows the results of evaluation of various physical properties.

(Resin synthesis example 3)
The resin raw material and solvent were DSDFBP 64.2 g (0.152 mol), DFBP 49.8 g (0.228 mol), TMBPF 97.4 g (0.380 mol) and potassium carbonate 65.7 g (0.475 mol), and DMSO 845.4 g and 168.7 g (yield 86%) of polymer powder (resin 3) was obtained in the same manner as in Resin Synthesis Example 1 except that 281.8 g of toluene was used. Table 1 shows the results of evaluation of various physical properties.

(Resin synthesis example 4)
The resin raw material and solvent were DSDFBP 80.2 g (0.190 mol), DFBP 41.5 g (0.190 mol), TMBPF 97.4 g (0.380 mol) and potassium carbonate 65.7 g (0.475 mol), and DMSO 876.4 g and 174.6 g (yield 86%) of polymer powder (resin 4) was obtained in the same manner as in Resin Synthesis Example 1 except that 292.1 g of toluene was used. Table 1 shows the results of evaluation of various physical properties.

(Resin synthesis example 5)
The resin raw material and solvent were DSDFBP 96.3 g (0.228 mol), DFBP 33.2 g (0.152 mol), TMBPF 97.4 g (0.380 mol) and potassium carbonate 65.7 g (0.475 mol), and DMSO 907.5 g and 173.6 g (yield 82%) of polymer powder (resin 5) was obtained in the same manner as in Resin Synthesis Example 1 except that 302.5 g of toluene was used. Table 1 shows the results of evaluation of various physical properties.

(Resin synthesis example 6)
Resin raw materials and solvents were 160.5 g (0.380 mol) of DSDFBP, 97.4 g (0.380 mol) of TMBPF and 65.7 g (0.475 mol) of potassium carbonate, and 1031.5 g of DMSO and 343.8 g of toluene. 165.0 g (yield 68%) of polymer powder (resin 6) was obtained in the same manner as in Synthesis Example 1. Table 1 shows the results of evaluation of various physical properties.

(Resin synthesis example 7)
The resin raw material and solvent were DSDFBP 91.5 g (0.228 mol), DFBP 33.2 g (0.152 mol), TMBPF 94.5 g (0.369 mol), TPPA 4.8 g (0.011 mol) and carbonic acid represented by the following formula. Polymer powder 181.7 g (yield 87%) (resin 7) was obtained in the same manner as in Resin Synthesis Example 1 except that potassium 65.7 g (0.475 mol), DMSO 895.9 g and toluene 298.6 g were used. Table 1 shows the results of evaluation of various physical properties.

（樹脂合成例８）
樹脂の原料および溶媒を、ＤＳＤＦＢＰの代わりにＤＳＤＣＤＰＳ６３．１ｇ（０．１５２ｍｏｌ）、ＤＦＢＰの代わりにＤＣＤＰＳ６５．５ｇ（０．２２８ｍｏｌ）、ＴＭＢＰＦ９７．４ｇ（０．３８０ｍｏｌ）および炭酸カリウム６５．７ｇ（０．４７５ｍｏｌ）、ならびにＤＭＳＯ９０３．９ｇおよびトルエン３０１．３ｇとした他は実施例１と同様にしてポリマー粉１６０．２ｇ（収率７６％）（樹脂８）を得た。諸物性評価結果を表１に示す。

(Resin synthesis example 8)
The resin raw material and the solvent were DSDCDPS 63.1 g (0.152 mol) instead of DSDFBP, DCDPS 65.5 g (0.228 mol) instead of DFBP, TMBPF 97.4 g (0.380 mol) and potassium carbonate 65.7 g (0. 475 mol), and DMSO 903.9 g and toluene 301.3 g were obtained in the same manner as in Example 1 to obtain 160.2 g (yield 76%) of polymer powder (resin 8). Table 1 shows the results of evaluation of various physical properties.

[Example 1]
Resin 1 produced in Resin Synthesis Example 1 was dissolved in DMF to prepare a varnish, and this varnish was cast on a release sheet and dried at 150° C. for 10 minutes to obtain a resin 1 film. This was peeled from the release sheet to obtain a semi-permeable membrane 1 as a self-supporting membrane.

Next, a non-woven fabric (Syntex (registered trademark) PS-having a material of polypropylene having an air permeability of 300 m ³ /cm ² /s, a thickness of 290 μm, measured by the A method (Flagille type method) described in JIS L 1096). Two pieces of 105 Mitsui Chemicals, Inc. were prepared, the semipermeable membrane 1 was sandwiched between these nonwoven fabrics, and these were integrated to obtain a forward osmosis membrane 1. Table 2 shows the evaluation results of the forward osmosis membrane 1.

[Examples 2 to 9 and 11]
The forward osmosis membranes 2 to 9 were prepared in the same manner as in Example 1 except that the resin, the thickness of the semipermeable membrane, or the porous support used in the production of the semipermeable membrane was changed as shown in Table 2. I got 11. Table 2 shows the evaluation results of the forward osmosis membranes 2 to 9 and 11.

[Example 10]
Resin 5 was dissolved in NMP to prepare a varnish, the varnish was cast on a glass substrate, and dried at 150° C. for 10 minutes to obtain a resin 5 film. The obtained film was irradiated with light of 2000 mJ/cm ² using a metal halide lamp to obtain a semipermeable film 5. The semipermeable membrane 5 was peeled off from the glass substrate to form a self-supporting membrane, which was then sandwiched between nonwoven fabrics to integrate them to obtain a normal osmosis membrane 5-2000. Table 2 shows the evaluation results of the forward osmosis membrane 5-2000.

［比較例１］
樹脂合成例３で製造した樹脂３をＤＭＦに溶解させてワニスを調製し、このワニスを多孔質支持体層および多孔質ポリマー層からなる日東電工（株）製ＮＦ膜（商品名：ＮＴＲ７４５０）の多孔質ポリマー層上にキャストし、１５０℃で１０分乾燥して樹脂３の膜を得た。これをそのまま正浸透膜として評価に供した。評価結果を表６に示す。なお、このＮＦ膜の、ＪＩＳ Ｌ １０９６記載のＡ法（フラジール形法）で測定される通気度、厚さ、水透過流束および塩阻止率は、それぞれ２ｃｍ³／ｃｍ²／ｓ、１４５μｍ、２５．６Ｌ／（ｍ²・ｈ）、３．２ｍｏｌ／（ｍ²・ｈ）であった。

[Comparative Example 1]
Resin 3 produced in Resin Synthesis Example 3 was dissolved in DMF to prepare a varnish, and this varnish was used as a NF membrane (trade name: NTR7450) manufactured by Nitto Denko Corp., which was composed of a porous support layer and a porous polymer layer. It was cast on a porous polymer layer and dried at 150° C. for 10 minutes to obtain a film of resin 3. This was directly used as a normal osmosis membrane for evaluation. The evaluation results are shown in Table 6. The air permeability, thickness, water permeation flux and salt rejection of this NF membrane measured by Method A (Flagille type method) described in JIS L 1096 are 2 cm ³ /cm ² /s and 145 μm, respectively. It was 25.6 L/(m ² ·h) and 3.2 mol/(m ² ·h).

[Comparative Examples 2 and 3]
HTI forward osmosis membranes CTA-ES and CTA-NW comprising a porous support layer, a porous polymer layer, and a semipermeable membrane layer of cellulose triacetate were provided for evaluation as a comparison. The layer configurations and the evaluation results are shown in Tables 5 and 6.

1 feed solution tank 2, 12 flow path 3, 13 pump 4, 14 balance 10 evaluation device 11 draw solution tank 15 electric conductivity meter 21 evaluation cell 22 forward osmosis membrane DS draw solution FS feed solution

Claims (9)

A forward osmosis membrane comprising a semipermeable membrane and a porous substrate disposed on at least one surface thereof,
The semipermeable membrane comprises a protonic acid group-containing aromatic polyether resin containing a structural unit (1) represented by the following formula (1) and a structural unit (2) represented by the following formula (2). ,
The porous substrate is a normal osmosis membrane having an air permeability of 100 to 400 cm ³ /cm ² /s and a thickness of 50 to 700 μm, which is measured by the A method (Flagille type method) described in JIS L1096.

[In formulas (1) and (2),
R ^{1 to} R ¹⁰ are each independently H, Cl, F, CF ₃ or C _m H _2m+1 (m represents an integer of 1 to 10),
At least one of R ^{1 to} R ¹⁰ is C _m H _2m+1 (m represents an integer of 1 to 10),
R ^{1 to} R ¹⁰ may be present in two or more in each aromatic ring, and when two or more C _m H _2m+1 are present in one aromatic ring, each C _m H _2m+1 is mutually present. It may be the same or different.
X ^{1 to} X ⁵ are each independently H, Cl, F, CF ₃ or a protonic acid group,
At least one of X ^{1 to} X ⁵ is a protonic acid group,
X ^{1 to} X ⁵ may be present in two or more in each aromatic ring, and when two or more protic acid groups are present in one aromatic ring, the protic acid groups may be the same or different. May be.
A ^{1 to} A ⁶ are each independently a direct bond, —CH ₂ —, —C(CH ₃ ) ₂ —, —C(CF ₃ ) ₂ —, —O— or —CO—.
i, j, k and l each independently represent 0 or 1. ] When the molar fractions of the structural unit (1) and the structural unit (2) with respect to the total amount of the structural unit (1) and the structural unit (2) are p and q, respectively, p/q=10/90 to The forward osmosis membrane according to claim 1, which is 70/30. The forward osmosis membrane according to claim 1 or 2, wherein the proton-acid-group-containing aromatic polyether resin has a weight average molecular weight of 70,000 or more. The forward osmosis membrane according to claim 1, wherein the semipermeable membrane has a thickness of 3 μm or less. The forward osmosis membrane according to any one of claims 1 to 4, wherein the tensile rupture strength and the elongation are 40 MPa or more and 40% or more, respectively. The forward osmosis membrane according to any one of claims 1 to 5, comprising the semipermeable membrane and the porous base material arranged on both surfaces thereof. A forward osmosis membrane element comprising the forward osmosis membrane according to any one of claims 1 to 6 and a spacer. A forward osmosis membrane module comprising the forward osmosis membrane element according to claim 7 housed in a container. The normal osmosis membrane module according to claim 8, and for feeding a feed solution to one surface of the normal osmosis membrane included in the normal osmosis membrane module and a draw solution having a higher concentration than the feed solution to the other surface. A drive pump for transporting water contained in the feed solution through the forward osmosis membrane to the draw solution.

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