JPS6099306A - Permselective composite membrane and its preparation - Google Patents

Abstract

PURPOSE:To obtain a permselective composite membrane having high chlorine resistance by crosslinking polyallylamine with a compd. having >=2 functional groups capable of reacting with prim. amino group on a supporting film. CONSTITUTION:A soln. obtd. by dissolving polyallylamine in water, hydrophilic solvent or a mixture thereof is coated on a porous supporting film or impregnated into the film. After removing excess soln. if necessary, by flowing down, obtd. composite body is allowed to contact with a compd. having at least two functional groups capable of reacting with prim. amino group, heating thereafter, if necessary, to perform crosslinking reaction. Suitable hydrophilic solvent is methanol, and suitable concn. of the film forming liquid is 0.05-10wt%. The crosslinking reaction is performed with 0.05-10wt% concn. of the crosslinking agent and 10sec-10min contact time, then heating at room temp. -90 deg.C, further heating at 100-130 deg.C for 2-30min.

Description

Detailed Description of the Invention Technical Field The present invention provides a new permselective composite membrane and a method for producing the same, and more specifically, a permselective composite membrane with high chlorine resistance in addition to high permselectivity, and its manufacturing method. This relates to a manufacturing method.

BACKGROUND ART Cellulose acetate reverse osmosis membranes, which are currently widely used, have excellent basic performance, but have problems in terms of hydrolyzability, deterioration due to microorganisms, and compactability.

Many synthetic polymer membrane materials have been proposed that do not have these drawbacks.

For example, a composite membrane based on polyethyleneimine cross-linked with a polyfunctional compound (U.S. Pat. No. 4,039,440)
(see US Pat. No. 4,006,000), a composite membrane based on cross-linked amine-modified polyepichlorohydrin (U.S. Pat.
05,012), composite membranes based on similarly cross-linked acrylonitrile-modified polyethyleneimine (see U.S. Pat. No. 3,951,815), and composite membranes based on similarly cross-linked polydiallylamine polymers (see US Pat. No. 3,951,815). A composite membrane (Japanese Unexamined Patent Publication No. 54-151570) has been proposed as a membrane that improves the above-mentioned drawbacks of cellulose acetate membranes. However, such polyamine-based membranes do not have sufficient chlorine resistance, and their performance deteriorates due to chlorine sterilization, and furthermore, when used continuously for a long time, their performance deteriorates due to the action of chlorine in tap water. Said U.S. Pat. No. 3,951.8
Although the specifications of No. 5 and JP-A-151570 claim that the obtained membrane has excellent chlorine resistance, it is not sufficient and it is generally modified to improve oxidation resistance. Composite membranes tend to have significantly reduced water permeability.

DISCLOSURE OF THE INVENTION The present inventor has conducted various studies in order to solve the problems of cellulose acetate-based composite membranes and develop a composite membrane with excellent chlorine resistance using a polyamine polymer as a base material, and has come to the following conclusion. reached.

In other words, when cross-linked using the same cross-linking agent, the chlorine resistance of the resulting composite membrane depends on the type of amino groups in the polyamine used as the substrate, and the Amino group ≧ quaternary ammonium group.

The order is In other words, the chlorine resistance of a composite membrane based on a polymer containing only primary amino groups can be improved by using a polyamine containing only secondary amino groups or a polyamine partially containing tertiary amino groups and/or quaternary ammonium groups. It was concluded that the chlorine resistance of the composite membrane used as the base was superior.

The present inventor has prepared polyallylamine (monoallylamine polymer), which is a polyamine polymer containing only primary amino groups, on a porous support membrane, which contains two or more groups in the molecule that react with primary amino groups. The present invention was completed by discovering that a composite membrane obtained by crosslinking by reacting with a compound has high permselectivity and extremely excellent chlorine resistance.

There is a permselective composite membrane characterized in that the compound (II) having at least two groups is used.

The present invention also provides polyallylamine (I) and a compound (I[) having at least two functional groups that react with the 17th amino group.
A permselective method characterized by contacting with the above on a porous support membrane (A), and heat-treating as necessary to destroy the cross-linking reaction and form a polyallylamine cross-linked reactant (B). In the method for manufacturing a composite membrane.

BEST MODE FOR CARRYING OUT THE INVENTION According to one aspect of the method for producing a permselective composite membrane of the present invention, the polyallylamine (I) is dissolved in water, a hydrophilic solvent, or a water-hydrophilic solvent mixed solvent. After coating or impregnating the porous support membrane (A) with the solution, excess solution is removed by flowing down as necessary, and the resulting composite is treated with at least one functional group that reacts with the 17th amino group. A compound having two (II
), and then, if necessary, heat-treating the axillary composite to carry out a cross-linking reaction. Note that the hydrophilic solvent includes lower alcohols, particularly methanol, but is not limited thereto.

According to another aspect of the method for producing a permselective composite membrane of the present invention, a polyallylamine (In! solution) to which the compound (II) as a crosslinking agent has been added in advance is mixed with a porous support membrane (
After coating or impregnating A), the polyallylamine (I) and the compound (II) may be reacted on the porous support membrane.

The polyallylamine (I) used in the present invention is a polyamine containing only primary amino groups, but no industrial method for producing it has been known so far. Recently, the present inventor has discovered that an inorganic acid salt of polyallylamine can be obtained very easily by polymerizing an inorganic acid salt of monoallylamine in an aqueous medium using a specific azo initiator.
We have established an industrial method for producing polyallylamine and have filed a patent application for this (Japanese Patent Application No. 54988-1988). An example of the manufacturing method is described below as a reference example, so please refer to it.

Next, the solution of polyallylamine (4) obtained in this way is applied or impregnated to form a porous support membrane (A) that is used to produce a composite membrane.
~3000A, preferably 100~ioooM, membrane constant C2kll/cm" permeation amount of pure water under pressure of 1~10-', !i'/crn2-sec atm, preferably 10-"~10 -3. ji'/2"・s
An asymmetric structure of ea-atm is preferred. Membrane materials include polyether sulfone, polyvinyl chloride,
Polyacrylonitrile, cellulose acetate, chlorinated polyvinyl chloride, and polypropylene are used, but the most desirable one is wholly aromatic polyether sulfone. These porous support membranes (A) are preferably used with one side reinforced with cloth or nonwoven fabric. Materials for such cloth or nonwoven fabric include polyethylene terephthalate, polystyrene, polypropylene, nylon, or polyvinyl chloride.

The concentration of the polyallylamine (I) solution when coating or impregnating onto such a porous support membrane (A) is 0.05 to 1.
0 wt%, preferably 0.1 to 5 wt%. Next, the polyallylamine (I) solution coated on the porous support membrane is usually air-dried and then cross-linked with a cross-linking agent, compound (II). It is also possible to apply or impregnate the porous support membrane (A) with a mixed solution obtained by mixing the compound (n) which is the agent.

Compound (II), which is a crosslinking agent used in the present invention, is preferably formaldehyde or a halogen group,
Aldehyde group, epoxy group, acid anhydride group, acid halide group, N-chloroformyl group, chloroformate group, imir group
Compounds having at least two functional groups of one or more types selected from ether groups, amidinyl groups, and isocyanate groups, representative examples of which include the following: .

Br + OH2su Br (nl −2 to 10 integer)
[X=O1 or Br] 0HO (-OH2 cans possible OHOI: ng = 0 to 10
]CR1 is H or OH3, n3 = 0 to 10
[integer of] glycerin di- or triglycidyl ether, 1,1.1-)limethylolpropane di- or triglycidyl ether, pentanylthritol-di, tri- or tetraglycidyl ether, unrubitol-di, tri- or tetraglycidyl ether , Aralkyl group] S/ S/ g These compounds may be used alone or in combination of two or more.

A solution obtained by dissolving the crosslinking agent (II) in an organic solvent with a not too high boiling point, such as methylene chloride, benzene, hexane, etc., is applied to the porous support membrane (A). ) A cross-linking reaction is carried out by contacting with the polyallylamine (I) film formed by applying the solution and air-drying it to obtain a polyallylamine cross-linking reaction product (B). As mentioned above, the crosslinking agent (■) may be added to the polyallylamine (I) solution in advance.

The concentration of crosslinking agent (II) is 0.05 to 1 Q wt%
, preferably from 0.1 to 5 Wt %, and the contact time is from 10 seconds to 10 minutes, preferably from 50 seconds to 3 minutes.

Although the crosslinking reaction often proceeds even at low temperatures, in order to complete the reaction, after heating from room temperature to 90°C,
It is desirable to perform heat treatment at 160°C for 2 to 60 minutes.

The composite membrane obtained according to the present invention can be used in various modular forms, but the spiral form is the most desirable.

The composite membrane of the present invention has extremely excellent chlorine resistance in addition to high water permeability, excellent selective separation properties, compaction resistance, and organic solvent resistance.

The following is a reference example of the production of polyallylamine (I) used in the present invention.

Reference Example In 1.1 klI of concentrated hydrochloric acid (65% by weight), under water cooling, 5 to 1
Monoallylamine (OH2=
570 g (1 ρ mol) of 0H-OH2N)h) is added dropwise. After the dropwise addition is completed, water and excess hydrogen chloride are distilled off at 60° C. under a reduced pressure of 20 mercury columns using a rotary evaporator to obtain white crystals. The crystals were dried on a drying silica sol at 80°C under a reduced pressure of 5 units of mercury,
Monoallylamine hydrochloride (hereinafter referred to as MAA-Hol)
Get 980#. This MAA-HOI contains approximately 5% water.

1590 g of the above MAA-HO was placed in a 21 round bottom flask equipped with a stirrer, a thermometer, a backflow condenser, and a nitrogen gas inlet tube.
(6 mol) and 210 Il of distilled water were added and stirred to dissolve and prepare a 70% aqueous solution of MAA-HOI.

The solution is heated to 50° C. while passing nitrogen gas.

radical initiator 2,2'-diamidinyl-2-2'
-Agpropane dihydrochloride, -7g in distilled water 20111
Add the solution dissolved in /. It will generate heat after about 1 hour, so cool it while stirring and keep the temperature of the liquid at 48-52°C. After 60 hours, the same amount of initiator was added again, and
Polymerization is continued at 50°±1° C. for 0 hours. A colorless, transparent and viscous solution is thus obtained. When this solution is added to a large amount of methanol, a white polymer precipitates out. This precipitate was collected by filtration, washed with methanol, and then dried under reduced pressure at 50°C.
(referred to as OI). The number average molecular weight Mn of this FAA-[01 is 7,500.

Next, add 19 g (0.2 mol) of this FAA-HOI to 11 mol of distilled water in which 8.0 g of sodium hydroxide is dissolved. ) is obtained. This solution is used as it is in the production of the composite membrane of the present invention.

In the Examples described below, this aqueous solution will be abbreviated as PAA-solution.

In addition, 19 g of FAA-MCI was finely ground and 1110 g of methanol was dissolved in 8.09 g of sodium hydroxide. ! 9 and react at room temperature for 6 hours. Thereafter, the precipitated common salt is filtered off to obtain a solution of PAA in about 1 timemethanol. In the Examples, this solution is abbreviated as FAA-Solution B.

In addition, an aqueous solution of FAA-HCl is passed through a column filled with a strongly basic ion exchange resin (Amberlite-IRA-402) at °C to remove hydrochloric acid, and the obtained aqueous FAA solution is concentrated under reduced pressure and then freeze-dried. Accordingly, powdered PAA can be obtained. This may be dissolved in water, methanol or a mixture thereof to prepare a PAA-solution. Hereinafter, the present invention will be explained in more detail with reference to Examples and Comparative Examples.

Example 1゜FAA-solution B prepared by the method described in the reference example was added with Borietes kS/l/Hon (Udel-p 3500
■ Porous support membrane (manufactured by UCC, USA) (membrane constant: 6.1 - 1)
0"-21/am"・sec-atm;Po1 on the back side
(reinforced with a nonwoven fabric of Noethylene Tele 7 Talate) was immersed for 2 minutes and then air-dried for 10 minutes. Next, the membrane was immersed for 2 minutes in a 2% by weight n-hexane solution of terephthalic acid Loli-P, the n-hexane adhering to the membrane surface was evaporated, and the membrane was placed in a dryer at 110° to 120°. It was heat treated at C for 10 minutes.

When the thus obtained composite membrane was subjected to a reverse osmosis test at a temperature of 25°C and a pressure of 40 kg/am2 using 0.5% salt aqueous solution as raw water, the water permeability after 24 hours was 45-21. / m2・hr % desalination rate 9B, 2%
The result was obtained.

Next, add sodium hypochlorite and a buffer solution to the above raw water.
．． Continuing the reverse osmosis test at H, 5.0, and chlorine concentration of 5 to 61, water permeation rate was 35.5//m"/h after 100 hours.
r, desalination rate 98.0%, water permeability 32.5 after 300 hours
A result of 1/1 rL"hr", a salt removal rate of 97.8% was obtained.During the test, a sodium hypochlorite solution was added to the raw water to maintain the chlorine concentration at 5 to 6 at all times.

Here, the salt removal rate is a value expressed by the following formula.

Comparative Example 1 A composite membrane obtained in the same manner as in Example 1 using a 2% aqueous solution of polyethyleneimine (molecular weight 30.000) was subjected to a reverse osmosis test under the same conditions as in Example 1. Later water permeability 52.01
/ m”hr, a good value of 98.2% desalination rate was obtained, but after 200 hours it was 70.21 / m2・hr.
, , a significant performance drop of 38.5% was observed.

Comparative Example 2 Into a 300 cc three-necked flask equipped with a stirrer, a thermometer, and a backflow condenser, 60.9 g of diallylamine hydrochloride was added, and 34.9 g of distilled water was added to dissolve it uniformly. 6 g of ammonium persulfate dissolved in 6 g of distilled water is added to this solution and polymerized at 50°±2° C. for 24 hours. Next, a solution of 0.6 g of ammonium persulfate dissolved in 6 g of distilled water was added,
Polymerization was continued for an additional 24 hours. After the polymerization, the solution was added to a large amount of methanol to precipitate the polymer, separated by filtration, dried at 50°C under reduced pressure, and prepared as polydiallylamine hydrochloride 46I.
1, this polymer 13.5. F was dissolved in 950 I of distilled water in which 4 I of sodium hydroxide was dissolved to obtain an aqueous solution of about 196 polydiallylamine. Using this aqueous solution, Example 1
A reverse osmosis test was conducted on the composite membrane obtained in the same manner as in Example 1 under the same conditions as in Example 1. After 24 hours, the water permeation rate was 27-2 l/m"-hr % and the desalination rate was 96.7%.
, 32.21/m2・hr after 200 hours, 78.
A value of 6% was obtained, indicating a decrease in performance.

Example 2゜The BAA-solution A shown in the reference example was used instead of the BAA-solution B used in Example 1, and the same porous support membrane used in Example 1 was placed in this solution for 2 minutes. After soaking, 3
Air-dried in a nitrogen atmosphere for 0 minutes. Next, the layer was immersed for 2 minutes in a 6% by weight solution of epichlorohydrin in methylene chloride, the methylene chloride adhering to the membrane surface was evaporated, and the layer was heat-treated at 100 to 110° for 10 minutes in a dryer.

A reverse osmosis test was conducted on the thus obtained composite membrane under the same conditions as in Example 1, and the following results were obtained.

Water permeability (J/m2・hr) Salt removal rate after 4 hours 42.5 98.2 After 200 hours 54.6 89.3 Example 3゜In PAA-solution A100I whose preparation method was shown in the reference example , Nato2methylene-bisamidine 2I was dissolved, and the same porous support membrane used in Example 1 was immediately immersed for 2 minutes, air-dried, and then heat-treated at 100 to 120° for 20 minutes. A reverse osmosis test was conducted on the thus obtained composite membrane under the same conditions as in Example 1, and the following results were obtained.

Water permeability ()/2・hr) Salt removal rate after 4 hours 85.5 98.2 After 200 hours 120.5 86.2 Example 4 1% by weight of tolylene diisocyanate as a crosslinking agent
A composite membrane was prepared in exactly the same manner as in Example 1, except that -hexane solution was used. The reverse osmosis test result of this membrane is 42
After 4 hours, water permeability was 26. Bl/ga・hr, desalination rate 95
．． It was 5%.

Example 5 A composite membrane was prepared in exactly the same manner as in Example 1, except that the 5° solution was used. The reverse osmosis test results of this membrane showed that after 24 hours, the water permeability was 65-2 J/m2·hr and the desalination rate was 96.2%.

Example 6 In the same manner as in Example 1, a membrane that had been immersed in FAA-solution B and then blown was kept in saturated formaldehyde vapor at room temperature for 10 minutes and then heat treated at 100 DEG C. for 5 minutes. The reverse osmosis test results for this membrane showed that the water permeability was 21-41 after 24 hours.
/ m”hr N desalination rate was 98.4%.

Agent Asamura Hako

Claims (1)

[Scope of Claims] It is characterized by consisting of a polyallylamine crosslinking reaction product (B) obtained by carrying out a 10-bridge reaction using the compound (n) of permselective composite membrane. (2) The permselective composite membrane according to claim 1, wherein the porous support membrane (A) is aromatic polyethyl polysulfone. (3) iY realylamine (I) and a compound (n) having at least two functional groups that react with a primary amine group are brought into contact on a porous support membrane (A), and heat treated if necessary. A method for producing a permselective composite membrane, which comprises carrying out a crosslinking reaction to form a polyallylamine crosslinking reaction product (B). (4) After applying or impregnating the porous support membrane (A) with a solution in which the polyallylamine (I) is dissolved in water, a hydrophilic solvent, or a water-hydrophilic solvent mixed solvent, excess The solution is removed by flowing down, and the obtained complex is brought into contact with the compound (II), and then, if necessary, the cough complex is heat-treated to perform a cross-linking reaction, and the polyallylamine cross-linking reaction product (B ).) The method according to claim 6. (5) After coating or impregnating the porous support membrane (A) with a polyallylamine (I) solution to which the compound (n) has been added in advance, the polyallylamine (I) and the polyallylamine (I) are coated on the porous support membrane. 7. The method according to claim 6, wherein the reaction with the compound (If) is carried out to form a polyallylamine crosslinking reaction product (B).