JPS62213806A - Semi-permeable composite membrane - Google Patents

Abstract

PURPOSE:To prepare a composite membrane of high permeability and chlorine resistance which performs permselective separation for producing super-pure water by providing an activated layer of polypierazinicarbonyl ethylene on a substrate membrane. CONSTITUTION:An activated layer of semi-permeable composite membrane having a major constitution unit shown in the formula is provided on a porous substrate membrane having micro-pores of less than diameter number 100Angstrom on the major part of its surface. Said activated layer comprises poly [1-(1- piperazinicarbonyl)ethlene] as major component. Said macromole is used in a solution of 0.1-10wt% concentration, and preferably 0.01-2wt% of an anion family surface-active agent is added. Further, if alkali metallic compound or a small quantity of polyfunctional amino compound is added, selective separability and durability are increased. Said macromole solution is spread over the substrate membrane. After being dried up in a room temperature -150 deg.C, water of polyfunctional reagent and non-miscible solution are spread, dried and heat treated to prepare a semi-permeable membrane.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a semipermeable membrane for selectively permeating and separating components of a liquid mixture, and particularly for desalinating and desalinating can water. It also selectively removes or recovers pollutants or effective substances contained therein from wastewater that causes pollution, such as dyeing wastewater and electrocoated paint wastewater, and ultimately contributes to the closure of wastewater. More specifically, the present invention relates to a high-performance semipermeable composite membrane that can be used to produce ultrapure water used in the production of semiconductors.

(Prior art) Semipermeable membranes conventionally used industrially include asymmetric membranes made from cellulose acetate, for example, U.S. Pat.
There are lob-type membranes described in Patent No. 33,132 and Patent No. 3.133.137. However, this membrane has problems with hydrolysis resistance, microbial resistance, rI4 drug resistance, etc. In particular, when trying to improve permeability, it is not possible to manufacture a membrane that has both pressure resistance and durability, so it is used in some cases. However, it has not yet been put to practical use in a wide range of applications. Research into new materials that eliminate the drawbacks of these cellulose acetate asymmetric membranes is being actively conducted mainly in the United States and Japan, but aromatic polyamides, polyamide hydrazides (U.S. Patent No. 3,567,632), Some of them, such as polyamic acid (Japanese Patent Publication No. 50-121168), crosslinked polyamic acid (Japanese Patent Publication No. 52-152879), polyimidazopyrrolone, polysulfonamide, polybenzimidazole, polybenzimidacylon, polyarylene oxide, etc. Although materials have been obtained that improve the drawbacks of cellulose acetate membranes, they are inferior to cellulose acetate membranes in terms of selective separation and permeability.

On the other hand, a composite membrane has been developed, which is a semipermeable membrane of a different type from the lobe type, in which a porous support crotch is coated with an active layer having substantially membrane performance. In composite membranes, it becomes possible to select the most suitable materials for the active layer and porous support membrane for each application, increasing the degree of freedom in membrane manufacturing technology. It also has the advantage of being able to be stored in a dry state, unlike lobe-type membranes that must be kept constantly wet.

There are two types of composite membranes: one in which the active layer is directly coated on a porous support membrane, and one in which the active layer is coated on the porous support membrane through a gelling layer. Specific examples of the former are U.S. Pat.
926,798 specification, JP-A-55-147106, JP-A-53-14046, JP-A-58-243
03@ Publication, Special Publication No. 56-500062, U.S. Patent No. 4,259.183, PB Report 80-
127574, etc., and is said to have chlorine resistance, heat resistance, and chemical resistance, but when trying to achieve high permeability, the active layer is applied very thinly, so it may cause scratches on the porous support or foreign matter. It is said that it is generally difficult to obtain high-performance membranes with good reproducibility in industrial production. Further, as specific examples of the latter, JP-A-49-133282, JP-A-5
5-49524 @ Publication, Special Publication No. 55-38164, PB Report 80-182090. Special Public Service 1986-27
202, Japanese Patent Application Laid-Open No. 56-40403, etc. are known.

The characteristics of these semipermeable membranes are that although they eliminate the difficulty of membrane formation during industrial production that was a problem with the aforementioned composite membranes without a gelling layer, they are difficult to form when subjected to reverse osmosis treatment under low pressure. In many cases, water permeability was low, and satisfactory membrane performance could not be obtained, and chlorine resistance, which is important for the actual use of reverse osmosis membranes, was insufficient.

Furthermore, in recent years, especially in the semiconductor and food fields, membranes with high water permeability and chlorine resistance have been desired rather than high desalination performance, but it has not been possible to obtain membranes that satisfy these requirements. .

[Problem that the invention seeks to solve]

As a result of intensive studies aimed at obtaining a membrane having both high water permeability and chlorine resistance, the present inventors found that a polymer having the following formula [I] as a main repeating unit is effective,
This has led to the present invention.

[Means for solving problems]

In order to achieve the above object, the present invention consists of the following configuration.

"A semipermeable composite membrane consisting of an active layer and a supporting membrane that supports the active layer, wherein the active layer has the following (1) as a main constituent unit.

C=0 In the present invention, a polymer having formula [I] as a main repeating unit is poly(1-(1-piperazinylcarbonyl)
ethylene], such as HakrOIIIOl,
Ch'em, Rapid, Commo, n, 1
9B2, 3.909. The polyfunctional reagent may be any agent that can react with the secondary amine in the polymer to form a crosslinked polyamide or polyurea, such as trimesic acid halide, benzophenonetetracarboxylic acid halide, Trimellitic acid halide, pyrometic acid halide, isophthalic acid halide, terephthalic acid halide, naphthalenedicarboxylic acid halide, diphenyldicarboxylic acid halide, pyridinedicarboxylic acid halide, benzenedisulfonic acid halide, tolylene diisocyanate, bis(P-isocyanate phenyl)methane In consideration of the solubility in the membrane forming solvent and the performance of the composite reverse osmosis membrane, 1 to rimesic acid chloride, isophthalic acid chloride, terephthalic acid chloride, and mixtures thereof are preferred.

The active layer in the present invention is a layer that substantially controls separation performance, and is mainly composed of a reaction product of the polymer and a polyfunctional reagent, and is used to facilitate membrane formation and improve performance. For this purpose, additives such as polyhydric alcohols and water-soluble polymers may be added, and alkaline metal salts such as sodium phosphate, mono-lithium hydroxide, etc. may be added to promote the reaction between the polymer and the polyfunctional reagent. It is also effective to add a hydrochloric acid scavenger, and furthermore, the combined use of a phase transfer catalyst or an acylation catalyst may also have a good effect.

The support membrane that disturbs the active layer is a porous support membrane that has virtually no separation performance, and has uniform fine pores or fine pores that gradually become larger from one side to the other. The size of the micropores on one side is about 10
It is preferable to use a supporting membrane having a structure in which the number of particles is 0 to 1,000. The above porous support membrane is a Millipore filter (VSW)
You can choose from a variety of commercially available materials, such as P) and Toyo Roshi (UKlo), but typically ``Office of Saline Watery, Research and Development Progress Report'' N, 359 (1).
968). Homopolymers or blends of polysulfone, cellulose acetate, cellulose nitrate, and polyvinyl chloride are usually used as the material. By casting the mold to a thickness of 0.5% by weight and wet solidifying it in an aqueous solution containing 0.5% by weight of sodium dodecyl sulfate and 2% by weight of DMF, the majority of the surface has micropores with a diameter of several hundred angstroms or less. A sexually supporting membrane is obtained.

Next, an example of the manufacturing method of the present invention will be shown. In the composite semipermeable membrane of the present invention, at least one side of a porous support membrane is coated with an aqueous solution (hereinafter collectively referred to as a composition) containing the poly(1-(1-piperazinylcarbonyl)ethylene) as a main component. Then, air drying and/or heat treatment is performed to evaporate some or all of the water, and the main component is a polyfunctional reagent dissolved in a solvent that is immiscible with water and does not dissolve the porous support membrane. It can be obtained by applying a solution of 100% by weight, causing a crosslinking reaction, and then drying.

The concentration of the composition for obtaining the composite semipermeable membrane of the present invention is such that the polymer is 0.
．． The amount is 1 to 10% by weight, preferably 1 to 4% by weight, and it is effective to add a surfactant to improve the wettability of the composition to the surface of the porous support membrane and ensure uniform adhesion.
Among these, anionic surfactants are preferred and can be selected from sodium dodecyl sulfate, sodium alkylbenzene sulfonate, and the like.

As the surfactant, it is generally good to use about 0.01 to 2 wt%. A water-soluble organic solvent that does not deteriorate the porous support membrane may be added to these compositions. In addition, the effect may be further increased by adding an alkaline metal compound such as sodium hydroxide, and further adding a small amount of a polyfunctional amine compound such as piperazine, 4-aminomethylpiperazine, m-phenylenediamine, etc. Gives preferable E'll in terms of selective separation, durability, etc. In addition, the polyfunctional reagent is usually 0.01 to 2.0% by weight.
is used by dissolving it in n-hexane or trichlorotrifluoroethane.

Any known application method can be applied to coating the porous support membrane with the composition, such as a method of coating the composition on the support membrane, a method of dipping the support membrane in the composition, etc. It will be done. Among these methods, the method of coating the composition is preferable from the viewpoint of uniform coating on one side of the porous support membrane, and also from the viewpoint of workability. When the porous support membrane is immersed in the composition, it is preferable to take measures in advance to prevent the composition from adhering to the other side of the porous support membrane in the coating step. In such a coating process, a draining process is generally provided to remove excess composition. As a method for draining the liquid, for example, there is a method of holding the membrane surface vertically and allowing it to flow down by gravity.

The coated porous support membrane is dried using an air dryer or a heated dryer at a temperature ranging from air temperature to 150°C. Since the time varies, the time can be selected within the range of 1 to 60 minutes. Further, a water-immiscible solution of a polyfunctional reagent is applied, the liquid is drained off, and a semipermeable membrane is obtained by air drying or heat treatment.

This drying step is usually carried out at a temperature ranging from room temperature to 150°C,
The time is determined depending on the temperature. The composite reverse osmosis membrane thus obtained can be used as is, but the surface of the active layer of the composite reverse osmosis membrane can be coated with a protective polymer film, and it is practically desirable to cover it with a protective film. The protective film is coated on the surface of the active layer by coating the surface of the dried composite reverse osmosis membrane with a polymer solution of the protective film, and then drying it. Examples of such polymers include water-soluble polymers such as polyvinyl alcohol, polyacrylic acid, and polyvinylpyrrolidone, with polyvinyl alcohol being particularly preferred in view of the strength of the coating.

These polymers are generally used as a 0.5 to 10% by weight aqueous solution, and the coating method is not limited to dipping, but can also be applied by spraying or brushing. The thus coated composite reverse osmosis membrane is dried in a hot air dryer to form the final product. As for the drying conditions, it is generally good to dry at a temperature in the range of 60 to 120°C for 2 to 10 minutes.

〔Example〕

In the following examples, the rejection rate of common salt as selective separation performance was determined by conventional means by measuring electrical conductivity.

In addition, as permeation performance, the water passage rate was determined by the amount of water permeation per unit area and unit time.

Reference example Taffeta made of polyester fibers with a length of 3Qcm and a width of 20cm (multifilament yarn of 150 denier for both warp and weft, weave density of 90 pieces/inch in length,
A 16 wt. W(2
A fiber-reinforced polysulfone support membrane (hereinafter abbreviated as FR-PS support membrane) is prepared by casting the membrane at 0° C., immediately immersing it in pure water, and leaving it for 5 minutes. The FR-PS support film thus obtained (thickness 210-215μ)
The pure water permeability coefficient of is measured at a pressure of 1 h/cJ and a temperature of 25°C, and is 0.005 to 0.01 Q/cJ -sec.
It was an ATM.

Example 1 Poly(1-
An aqueous solution (composition) containing 1.0% by weight of (1-piperazinylcarbonyl)ethylene] and 0.1% by weight of sodium dodecyl sulfate was applied to a volume of 150 ml/m'.
It was dried with hot air at 0°C for 1 minute. Thereafter, 60ml/7yls of a solution of 0.025% by weight of trimesic acid chloride dissolved in trifluorotrichloroethane was applied, followed by dry heat treatment with hot air at 120°C for 3 minutes. The composite membrane thus obtained was subjected to a pressure of 15 kg/c.
/, raw water 0° 15% Na (4 aqueous solution under conditions of 25°C,
As a result of reverse osmosis testing, the salt removal rate after 15 hours was 30%, and the water permeation rate was 12.6 m'/m2·day. In addition, chlorine was added to this raw water to make the conditions such that the residual chlorine was 1 pOIII and the pH was 6°5.The performance was evaluated after 15 hours, and the salt removal rate was 35% and the water permeation amount was 2.3 m'/m2·day.

Furthermore, when residual chlorine was removed and operation was continued for 26 hours under the same conditions, the salt removal rate was 32%, and the amount of water permeation was 2.4.
m'/ln2·day, indicating good chlorine resistance.

In addition, the active layer of this film was transferred to the ESC, FT-IR, "'C
-N) When analyzed by IR spectrum, a structure containing a carboxylic acid terminal and crosslinked with trimesic acid chloride as a unit of formula [I] was confirmed.

Examples 2 and 3 In Example 1, the concentration of trimesoyl chloride was
A composite membrane was obtained by changing the conditions as shown in Table 1 and keeping the other conditions the same. Table 1 shows the results of a reverse osmosis test under the same conditions as in Example 1.

Table 1 Evaluation conditions: Pressure 15 kg/at, 25°C, DH6.5 [
Effects of the Invention The composite membrane of the present invention is for permselective separation of liquid mixtures, and in particular can be used to produce ultrapure water used in the production of kansui and semiconductors.
At the same time, it has become possible to provide a membrane with high water permeability and chlorine resistance, which was previously difficult to achieve.

Claims (1)

[Claims] (1) A semipermeable composite membrane comprising an active layer and a support membrane supporting the active layer, wherein the active layer has the following [I] as a main constituent unit. ▲There are mathematical formulas, chemical formulas, tables, etc.▼(I)