JPH0518845B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention consists of a polymer polyA that can introduce an anion exchange group made of a nitrogen-containing vinyl compound and a polymer that can insert a cation exchange group made of other monomers.
By reacting an alkyl dihalogen compound to a molded block copolymer containing polyB as a part or the entire component, an anion exchange group is introduced into the polyA part, and a cation exchange group is further introduced into the polyB part. The present invention relates to a method for producing an amphoteric ion exchanger. In recent years, materials with multiphase structures have attracted attention in fields such as medical materials and materials for separation membranes because they can exhibit specific functions that do not exist in homogeneous materials. Among these, amphoteric ion exchangers, in which a micro region with a cation exchange group and a micro region with an anion exchange group exist at the same time, are used as medical materials due to the effects of both fixed charges. It is said that it can be expected to have high cell affinity and be used as a separation membrane and have high permeability to inorganic ions. Amphoteric ion exchangers with such a microscopic multiphase structure can be produced using the microphase separation phenomenon in block copolymers; The destabilization of the microstructure due to swelling by water or organic solvents after introduction has been considered a problem. (Reference, OSW R&DP Report No. 689) In order to improve these points, in addition to polymers into which cation exchange groups can be introduced and polymers into which anion exchange groups can be introduced, crosslinking is possible without introducing ion exchange groups. A method for producing an amphoteric ion exchanger from a tertiary block copolymer having a diene polymer as a component block has been proposed. (Publication of Patent Publication No. 56-76408) However, even in such a ternary block copolymer, the initially formed microstructure is easily disturbed after the introduction of ion exchange groups, making it insufficient as a material for the above purpose. I can't say that. The component block of such a block copolymer into which an anion exchange group can be introduced is usually composed of a monomer having a tertiary amino group. For amphoteric ion exchangers, after molding a block copolymer, the part consisting of the component blocks is first quaternized by reaction with an alkyl halide compound such as methyl iodide to form a region having anion exchange groups, and then other parts are formed. It can be obtained by introducing a cation exchange group into the component block and further crosslinking a neutral component as necessary. Cation exchange groups can be introduced by hydrolysis of ester groups or cyano groups, or by sulfonation of aromatics, but during these reactions, the block copolymer molded product is swollen greatly in a solvent. This may cause the initial microphase structure to be disturbed. In particular, when a cation exchange group is introduced by sulfonation of an aromatic ring, the reaction is so violent that defects tend to occur in the membrane. The present invention was made with the aim of solving this problem and obtaining an amphoteric ion exchanger with excellent performance. That is, after extensive research, the present inventors have determined that a _tertiary amino group can be converted into 4 by using an alkyl dihalogen compound represented by the general formula After grading, cross-linking in the neutral region and introducing cation exchange groups into regions where cation exchange groups can be introduced will ultimately yield an amphoteric ion exchanger that maintains its initial microstructure. I discovered that. The present invention will be explained in detail below. The present invention includes monomer group A: vinylpyridines such as 2-vinylpyridine, 4-vinylpyridine, and 2-methyl-5-vinylpyridine, vinylpyridines, vinylquinolines, vinylcarbazoles, vinylimidazoles, and o, m, p- (n = 1 to 3, R ₁ and R ₂ are alkyl groups each having 1 to 12 carbon atoms)
Polymer polyA that can introduce an anion exchange group made of a monomer selected from vinyl phenyl alkylene dialkylamide derivatives, and polymer polyB that can introduce a cation exchange group made of other monomers.
A molded product of _the original block copolymer having 5% or more by weight of each of The present invention relates to a method for producing an amphoteric ion exchanger, which comprises introducing an anion exchange group into the polyA portion by treatment with a solution containing the same, and further introducing a cation exchange group into the polyB portion. As is well known, block copolymers are made up of their respective component blocks by slowly evaporating the solvent from the solution, and are made up of domains with sizes defined by the lengths of the blocks. The molded product has a microphase-separated structure. The typical form of the phase that occurs at this time is
The shape may be lamellar, spherical, or rod-like, but it is determined by the composition of the block copolymer, the type of solvent used, temperature, etc. Therefore, the polyA mentioned earlier and
If molded polyB block copolymers can be chemically treated without destroying the microphase separation structure, it is possible to create a material that simultaneously has regions with cation exchange groups and regions with anion exchange groups as designed. It becomes possible to manufacture. From the above monomer group A, the polymer is X(CH ₂ )
When it comes into contact with an alkyl dihalogen compound represented by nX (X is bromine or iodine), it is rapidly quaternized and at the same time crosslinked. Furthermore, since the boiling point of these alkyl dihalogen compounds is high, the vapor pressure at the reaction temperature (usually from 0° C. to 100° C.) is low, and the material does not swell significantly with the alkyl dihalogen compounds during the reaction. For the above reasons, if a vapor alkyl dihalogen compound is used, an anion exchange group can be introduced into the polyA portion without disturbing the initial macroscopic and micro phase separation structure of the block copolymer molded product, and the anion exchange group can be introduced into the subsequent polyB portion. Even when introducing cation exchange groups, it is possible to minimize changes in structure and formation of polyion complexes. The block copolymer referred to in the present invention is composed of a polymer polyA into which an anion exchange group can be introduced and a polymer polyB into which a cation exchange group can be introduced (polyA-polyB).
_o , (polyA−polyB) _o polyA, polyB (polyA−
polyB) _o (n is an integer of 1 or more in each case). Among these block copolymers, when both ends are polyA, when the polyA portion is treated with a dialkyl halogen compound, all the microphases are connected by covalent bonds, and the microphase separation structure becomes more stable. Therefore, it is desirable as a material for obtaining a high converter of zwitterions. Further, the block copolymer may include a polymer polyC into which no ion exchange group is introduced. Such block copolymers include polyA-polyB-
polyC, polyB−polyA−polyC, polyA−polyC
- a tertiary block copolymer represented by polyB,
polyA−polyB−polyC−polyB, polyB−polyA
−polyC−polyA, polyA−polyB−polyC−
polyA, polyB−polyA−polyC−polyB, polyC
−polyA−polyB−polyC, polyC−polyA−
polyC−polyB, polyC−polyB−polyC−polyA
A quaternary block copolymer represented by polyA-
polyB−polyC−polyB−polyA, polyA−polyC
−polyB−polyC−polyA, polyB−polyA−
polyC−polyA−polyB, polyB−polyC−polyA
−polyC−polyB, polyC−polyA−polyC−
A 5-element block copolymer represented by polyB-polyC, etc., and (polyA-polyC-polyB) _x ,
(polyA−polyB−polyC) _x , (polyB−polyA−
polyC) _x , (polyA−polyC−polyB−polyC) _x ,
(polyB−polyC−polyA−polyC) _x (both x
is an integer of 2 or more). The component polymer polyB into which cation exchange groups can be introduced in the block copolymer used in the present invention needs to be able to easily introduce carboxyl groups, sulfone groups, phosphoric acid groups, etc.
Among these, polymers into which carboxyl groups can be introduced can be obtained from monomers of the following monomer group B ₁ ,
A carboxyl group can be introduced by hydrolysis. Monomer group B ₁ : unsaturated carboxylic acids such as acrylic esters, methacrylic esters, crotonic esters, conjugated diene carboxylic esters, acrylonitrile, methacrylonitrile,
Monomers with cyano groups such as vinylidene cyanide, alkylidene malonic acid esters, α-cyanoacrylic acid esters, etc. Hydrolysis of ester groups can be carried out using water or alcohol solutions such as sodium hydroxide or potassium hydroxide. Hydrolysis of the group can be carried out by e.g.
This can be easily carried out by a known method using concentrated sulfuric acid, concentrated hydrochloric acid, aqueous alkaline solution, or glycol monoethyl ether of potassium hydroxide. Further, a polymer into which a sulfone group can be easily introduced can be obtained from monomers of the following monomer group B ₂ or B ₃ . Monomer group B ₂ : styrene, α-methylstyrene,
Monomers with aromatic rings such as vinyltoluene, diphenylbutadiene, phenylhexisadiene, vinylnaphthalene, etc. Monomer group B ₃ : or,

[Formula] The monomer R ₃ is hydrogen or an alkyl group having 1 to 3 carbon atoms, and R ₄ , R ₅ and R ₆ are -CH ₃ , -C ₂ H ₅ , -
CH ₂ CH ₂ CH ₃ ,

【formula】

【formula】

【formula】

[Formula] etc. Alkyl group having 1 to 12 carbon atoms Sulfonation of the aromatic ring can be carried out by a known method using concentrated sulfuric acid, fuming sulfuric acid, sulfur trioxide, chlorosulfonic acid, etc. (New Experimental Chemistry Course, 14−
(Vol., p. 1776) On the other hand, polymers consisting of monomers of monomer group B ₃ can be converted into phenol form by removing the protecting group or with the protecting group still attached.
Sulfonation is easily possible by a similar method. Component polymer polyC that does not introduce ion exchange groups,
It is obtained from the following monomers of monomer group C. Monomer group C: diene monomers such as butadiene, isoprene, pentadiene, and cyclohexane. In the case of a sample with a neutral block composed of such diene monomers, this part can be easily crosslinked using known methods such as peroxide, sulfur, sulfur monochloride, concentrated sulfuric acid, or ultraviolet rays. can. It is also possible to hydrogenate by a known method. These increase the strength of the material. The molecular weights of the component polymers polyA, polyB, and polyC constituting the block copolymer used in the present invention are as follows:
The content is preferably 10 ³ to ^{10 6} g/mol. More preferably, it is 10 ⁴ to ^{5 5} ×10 ⁵ g/mol. As is generally well known, in block copolymers, as the molecular weight decreases, the volume fraction of the compatible interface area generated between two adjacent domains formed by microphase separation increases. Therefore, in a sample with a low molecular weight, the formation of polyion complexes is large, and the effect of having cation domains and anion domains simultaneously exist due to microphase separation is weakened. According to the experimental facts published so far for various block copolymers,
It is considered that when the molecular weight of each block is less than 10 ³ g/mol, a clear phase-separated structure is hardly formed. On the other hand, in the case of a sample with a large molecular weight, its viscosity increases in the solid or solution state, making it difficult to mold. The block copolymer of the present invention must contain 5% or more by weight of each of the component polymer polyA into which a cation exchange group is introduced and the component polymer polyB into which an anion exchange group is introduced. The reason for this is that the final amphoteric ion exchanger has positive or
This is because if the component segment having an anion exchange group is less than 5%, the effect will be significantly reduced due to the simultaneous presence of amphoteric ions. Such a block copolymer can be produced, for example, by a living anionic polymerization method. Examples of the polymerization initiator include known butyllithium (n, sec, tert, etc.), 2-methylbutyllithium, sodium naphthalene,
Sodium anthracene, α-methylstyrene,
Tetramer sodium, sodium biphenyl, etc. are used, and aromatic hydrocarbons, cyclic ethers, aliphatic hydrocarbons (generally benzene, toluene,
Polymerization is carried out in a vacuum or an inert gas atmosphere such as nitrogen gas or argon gas (in which tetrahydrofuran, n-hexane, cyclohexane, etc. are used). In order to obtain an amphoteric ion exchanger from the block copolymer produced in this way, first, after molding,
It is preferable to treat with a vapor or solution of X(CH ₂ ) _o X (n is 2 to 12, X is a bromine or iodine atom). In the quaternization reaction, various organic solvents can be used as reaction solvents that usually proceed rapidly at temperatures between 0°C and 100°C, but they must be non-solvents or poor solvents for polyB and polyC. is desirable in order to prevent changes in the initial microphase separation structure. After treating the polyA part in this way, if chemical treatments are performed in the order of cross-linking of the polyC part and hydrolysis or sulfonation of the polyA part, amphoteric ion exchange that maintains the initial microphase-separated structure and macroscopic structure is possible. You can get a body. The present invention will be explained below with reference to Examples. Example 1 In benzene purified through a sodium mirror,
Using 3.4 x 10 ^-4 mol of sec-betyllithium as an initiator, styrene, 4-vinylbenzylmethylamine (hereinafter abbreviated as 4-VBDMA) and isobrene were mixed into 7 g of isoprene, 15 g of styrene, 7 g of isoprene,
4-VBDMA25g, isoprene 7g in that order, 5
PolyC is added every 20 hours to perform polymerization.
An original block copolymer of type -polyA-polyC-polyB-polyC was obtained. Prior to polymerization, styrene was dried with calcium hydride, distilled under reduced pressure, further purified with sodium benzophenone, and vacuum distilled. Isoprene was distilled after drying with calcium and sodium hydride. 4-VBDMA is
After drying with calcium hydride and distilling under reduced pressure, it was further purified using a triphenylmethyllithium-lithium bromide system and vacuum distilled. A film with a thickness of about 50 μm obtained by solvent evaporation on mercury using a 5% by weight benzene solution of the original block copolymer obtained in this way was stained with osmium tetroxide and examined with a transmission electron microscope. Upon observation, a lamellar micro-separated structure was confirmed. In this figure, the white parts are polystyrene domains.
(S), the black part is the polyisoblend domain (I), the light black part is the poly(4-VBDMA) domain (A), and the lamella manipulation unit is -S-
It is written as I-A-I-. A similarly prepared film was left in 1,3-diiodopropane vapor for 48 hours at room temperature, then immersed in a 20 volume percent sulfur monochloride solution in nitromethane at room temperature for 3 hours, and then 2 volume percent sulfur monochloride solution in nitromethane. It was immersed in a 1,2-dichloroethane solution of sulfonic acid at room temperature for 15 minutes to obtain an amphoteric ion exchange membrane. The resulting membrane had a cation exchange capacity of 1.10 milliequivalents per gram of dry membrane, and an anion exchange capacity of 1.05 milliequivalents per gram of dry membrane. The sulfonated polystyrene portion was stained by immersing this membrane in a saturated aqueous solution of stannous chloride for 3 hours, and observation under a transmission microscope revealed that the sulfonated polyethylene layer ( S- ⁾ and the quaternized poly(4-) layer were stained.
A three ^- phase lamellar structure in which ^the VBDMA ( ^VBDMA ) layer ( A It was found that the microphase structure was maintained with almost no disturbance. Example 2 Using benzene purified through a sodium mirror as a solvent and 2.8 x 10 ^-4 mol of sec-butyllithium as an initiator, 15 g of styrene, 27 g of butadiene, and 18 g of 4-vinylpyridine were polymerized in this order in 3 steps every 20 hours. Pour into a tank and polymerize to form polyA-polyC.
- A polyB type ternary block copolymer was obtained. A film with a thickness of approximately 50 μm prepared from a 5% by weight dioxane solution of the obtained original block copolymer on mercury by solvent evaporation was stained with osmium tetroxide and observed with a transmission electron microscope. (S), polybutadiene (B), poly(4-
A three-phase lamellar structure in which the (vinylpyridine) layer (P) was arranged in repeating units of -B-S-B-P- was confirmed. A film prepared in the same manner was treated with 1,4-diiodobutane vapor at 30°C for about 80 hours.
It was immersed in a nitromethane solution of sulfur monochloride at a volume percent of 3 hours at room temperature, and then immersed in a 2 volume percent solution of chlorosulfonic acid in 1,2-dichloroethane at room temperature for 15 minutes to obtain an amphoteric ion exchange membrane. The cation and anion exchange capacities of the resulting membrane were 0.98 meq and 0.92 meq per gram of dry membrane, respectively. Furthermore, when this membrane was stained with a saturated aqueous solution of stannous chloride and observed under a transmission electron microscope, it was found that the initial three-phase lamella production was maintained almost without disturbance. Example 3 Using benzene purified through a sodium mirror as a solvent and sec-butyllithium 3.5×10 ^-4 mol as an initiator, 17 g of 4-VBDMA, 30 g of styrene, and
- 17g of VBDMA was added to the polymerization tank every 20 hours in 3 steps in this order to polymerize polyA-polyB.
-A polyA type block copolymer was obtained. An 80 μm thick film prepared from a 5% by weight benzene solution of the resulting original block copolymer on a mercury surface by solvent evaporation was stained with osmium tetroxide and observed with a transmission electron microscope. A lamellar structure in which layers (4-VBDMA) and polystyrene layers were alternately arranged was confirmed. A film prepared in the same manner was treated with 1,4-diiodobutane vapor at 30°C for about 100 hours, and then
An amphoteric ion exchange membrane was obtained by immersing the membrane in a solution of chlorosulfonic acid in volume percent in 1,2-dichloroethane for 20 minutes at room temperature. The cation and anion exchange capacities of the resulting membranes are, respectively, per gram of dry membrane.
They were 2.2 milliequivalent and 1.7 milliequivalent. Furthermore, when this membrane was stained with a saturated aqueous solution of stannous chloride and observed under a transmission electron microscope, it was found that the initial lamellar structure was basically maintained. Comparative Example 1 A film with a thickness of approximately 50 μm prepared in the same manner as in Example 2 from a 5% by weight benzene solution of the original block copolymer obtained in Example 2 was heated with methyl iodide vapor (at a saturated vapor pressure of approximately 1 /3) at 20°C for 8 hours, immersed in a 20 volume percent sulfur monochloride solution in nitromethane for 3 hours at room temperature, and then immersed in a 2 volume percent chlorosulfonic acid solution in 1,2-dichloroethane at room temperature. When the membrane was soaked in water for 15 minutes to form an amphoteric ion exchange membrane, the cation and anion exchange capacities of this membrane were as low as 0.85 milliequivalent and 0.50 milliequivalent per gram of dry membrane, respectively. Furthermore, when the sample was stained with a saturated aqueous solution of stannous chloride and observed under a transmission electron microscope, a lamellar structure was confirmed, but it was found to be quite disordered. Comparative Example 2 An amphoteric ion exchange membrane was prepared in the same manner as in Comparative Example 1, except that the polyA-polyB-polyA type block copolymer obtained in Example 3 was used as the original block copolymer. When fabricated, the resulting amphoteric ion exchange membrane was significantly deformed and had cracks and holes. Its cation and anion exchange capacity is
0.70 meq/g of dry membrane, respectively.
The value was as low as 0.25 milliequivalent. Further, when the sample was stained with a saturated aqueous solution of stannous chloride and observed under a transmission electron microscope, no lamellar structure was observed.

Claims (1)

[Claims] 1. A polymer polyA capable of introducing an anion exchange group made of a monomer selected from the following monomer group A:
A molded product of the original block copolymer containing 5% or more by weight of each of polyB and polyB, which can introduce a cation exchange group made of another monomer, is expressed by the general formula
By treatment with vapor or solution of an alkyl dihalogen compound represented by (CH ₂ )n
Introducing an anion exchange group into the polyA moiety, and
A method for producing an amphoteric ion exchanger, which comprises introducing a cation exchange group into the polyB moiety. Monomer group A: vinylpyridines such as 2-vinylpyridine, 4-vinylpyridine, and 2-methyl-5-vinylpyridine, vinylpyrimidines, vinylquinolines, vinylcarbazoles, vinylimidazoles, and (n=1 to 3, R ₁ and R ₂ each have 1 carbon number
12 alkyl groups) represented by o, m,
p-vinylphenylalkylenedialkylamine derivative. 2. The method for producing an amphoteric ion exchanger according to claim 1, wherein the polymer polyB into which a cation exchange group can be introduced is composed of a monomer selected from the following monomer group _B1 . Monomer group B ₁ : Unsaturated carboxylic esters such as acrylic esters, methacrylic esters, crotonic esters, and conjugated diene carboxylic esters, monomers with cyano groups such as acrylonitrile, methacrylonitrile, and vinylidene cyanide, alkylidene malones acid esters,
α-cyanoacrylic acid ester. 3. The method for producing an amphoteric ion exchanger according to claim 1, wherein the polymer polyB into which a cation exchange group can be introduced is composed of a monomer selected from the following monomer group _B3 . Monomer group B ₃ : A monomer represented by [Formula]. (R ₃ is hydrogen or an alkyl group having 1 to 3 carbon atoms, R ₄ , R ₅ and R ₆ are -CH ₃ , -C ₂ H ₅ , -
CH ₂ CH ₂ CH ₃ , [Formula] [Formula] [Formula] [Formula] etc. Alkyl group having 1 to 12 carbon atoms. ) 4. The method for producing an amphoteric ion exchanger according to claim 1, wherein the polymer polyB into which a cation exchange group can be introduced is composed of a monomer selected from the following monomer group _B2 . Monomer group B ₂ : styrene, α-methylstyrene,
Monomers with aromatic rings such as vinyltoluene, diphenylbutadiene, phenylhexadiene, and vinylnaphthalene. 5. The original block copolymer contains 30% or more by weight of a polymer polyC which does not introduce an ion exchange group and is made of a monomer selected from the following monomer group C. Method for producing amphoteric ion exchanger. Monomer group C: diene monomers such as butadiene, isoprene, pentadiene, and cyclohexadiene. 6 After treating the polymer polyA moiety into which an anion exchange group can be introduced with an alkyl dihalogen compound represented by the general formula X(CH ₂ )nX (X is a bromine or iodine atom, n is 2 to 12), 4. A method for producing an amphoteric ion exchanger according to any one of claims 1 to 3, characterized in that a cation exchange group is introduced into a polymeric polyB portion into which a cation exchange group can be introduced. 7 After treating the polymer polyA moiety capable of introducing an anion exchange group with an alkyl dihalogen compound represented by the general formula X (CH ₂ ) n A method for producing an amphoteric ion exchanger according to claim 1, 3, or 4, characterized in that a cation exchange group is introduced into a polymer polyB portion into which a cation exchange group can be introduced by . 8 After treating the polymeric polyA portion capable of introducing an anion exchange group with an alkyl dihalogen compound represented by the general formula X(CH ₂ )nX (X is a bromine or iodine atom, n is 2 to 12), ion exchange Claims 1 to 5 are characterized in that a polymer polyC portion into which no group is introduced is crosslinked, and then a cation exchange group is introduced into a polymer polyB portion into which a cation exchange group can be introduced. A method for producing an amphoteric ion exchanger according to any one of paragraphs.