JPS6283006A - Manufacturing process for separating functional material - Google Patents

Abstract

PURPOSE:To offer the cation selective absorptivity to the porous high-molecular membrane without damaging filter function by graft polymerizing the monomer carrying the cation exchange group with the porous base. CONSTITUTION:The porous base made of polyethylene porous membrane and the like are irradiated beforehand by electronic rays coming out of the electronic accelerator, reacted in contact with monomer by dipping into the acrylic acid solution or some other similar process, and graft polymerized with the monomer carrying the cation exchange group or the monomer carrying the functional group convertible to the cation exchange group. Through the said process, the cation in the mixed solution of various liquids is absorbed selectively and effectively, and the separating functional material having a composite function to filter and separate the mixed substance is produced.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for producing a separation functional material that selectively and efficiently adsorbs cations in various liquid mixed solutions and filters and separates mixed substances.

(Prior Art) Many separation and purification methods for liquid mixtures have been put to practical use and have contributed to the development of industry. For example, microfilter membranes can separate and purify fine particles and bacteria from aqueous liquids, and ultrafiltration membranes can separate colloids and pyrogenic substances. However, - all of the above membranes only have filtration and separation performance, and do not have a combined function of ion adsorption performance and filtration and separation performance. In addition, many attempts have been made to impart the above-mentioned composite functions, but it has been difficult to impart chemically and physically stable ion adsorption performance without impairing filtration performance, and these have been extremely unsatisfactory.

On the other hand, attempts have been made to make porous membranes from ion exchange resins;
The method of coating hydrous ion-exchange resins causes problems such as leakage of the ion-exchange material and decreases in dimensional stability, heat resistance, chemical resistance, especially durability, and physical properties, making it unsatisfactory. There are many points.

(Problems to be Solved by the Invention) With the development of modern industrial technology, there is a desire for higher functionality in separation and purification materials, and there is an urgent need to develop more advanced composite functional materials.

An object of the present invention is to provide a method for producing a material with excellent multifunctionality that eliminates the above-mentioned drawbacks.

(Means for Solving the Problems) The present invention involves graft polymerization, particularly radiation graft polymerization, of a monomer containing a cation exchange group or a monomer having a functional group exchangeable to a cation exchange group onto a porous substrate. This is a method for producing a separation functional material characterized by the following.

Hereinafter, the configuration of the present invention will be explained in detail.

The porous substrate used in carrying out the present invention is
Any material may be used as long as the monomer can be graft-polymerized by radiation irradiation, such as porous polymer membranes and porous polymer membranes containing inorganic substances. Examples of the membrane material include polyolefins, halogenated polyolefins, polyesters, polyethers, cellulose, and copolymers thereof, with olefin polymers and halogenated olefin polymers being particularly preferred.

The shape of the porous base material may be a flat membrane, a tube, or a hollow fiber. The pore structure of the porous base material is better than a straight pore structure obtained by a stretching method or an etching method.
Publication No. 40-957 and Special Publication No. 47-
Those having a three-dimensional network structure formed by the microphase separation method, mixed extraction method, etc. disclosed in Japanese Patent No. 17460 are preferred. In particular, with the establishment of the manufacturing technology for the structure shown in Japanese Patent Application Laid-Open No. 55-131028,
The significance of the present invention has been clarified, and a method for manufacturing a material with excellent performance that cannot be obtained with conventional techniques has been achieved.

The monomer containing a cation exchange group or the monomer having a functional group convertible into a cation exchange group used in the present invention includes carbonized monomers having a sulfonic acid group, a carboxylic acid group, a phenolic hydroxyl group, or an alkali metal salt thereof. Examples include hydrogen-based or halogen-containing hydrocarbon-based materials. Specifically, vinylsulfonic acid, styrenesulfonic acid, acrylic acid, methacrylic acid, paravinylphenol, fluorovinylsulfonic acid, fluorovinylcarboxylic acid, and styrene may be used alone or in combination of two or more thereof.

Radiant cotton is used to graft-polymerize the monomer onto the porous substrate. The ionizing radiation used is alpha rays, beta rays, and γ rays.
rays, accelerated electron beams, X-rays, etc., but electron beams or γ-rays are practically preferred. The method of graft polymerization is to irradiate the porous base material and monomer with radiation,
There is a simultaneous irradiation method in which the porous base material undergoes graft polymerization, and a pre-irradiation method in which only the porous base material is irradiated with radiation in advance, and then the monomer is brought into contact with the porous base material for graft polymerization. The pre-irradiation method is preferable because the problem arises that while the graft polymerization of monomers onto the material progresses, only the monomers that do not participate in the graft polymerization are homopolymerized, thereby clogging the pores of the porous base material. In the pre-irradiation method, the base material is irradiated with radiation before contacting the monomer with the porous base material, and the temperature is maintained at -10"C or less until it comes into contact with the monomer, and the temperature is kept at 50 °C or less, preferably 15 °C to 50 °C. Graft polymerization is carried out by contacting the monomer at a low temperature of 30°C.If the porous substrate is not stored at a low temperature after irradiation, the generated radicals will rapidly decay and will disappear after 30 minutes at room temperature (25°C). The number will be halved.Furthermore, at the same time, the generated radicals will react with a trace amount of adsorbed oxygen, resulting in a defect that impairs the heat and chemical resistance of the target substance.Furthermore, if the graft polymerization temperature exceeds 60°C, the graft Homopolymerized monomers of monomers that do not participate in polymerization may be generated and block the pores of the porous substrate, or homopolymerized monomers that are not extracted in the post-treatment process after the reaction may flow out after hydrophilization and cause secondary Problems such as causing pollution arise.

Hereinafter, the structure and effects of the present invention will be specifically described with reference to Examples, but these are not intended to limit the present invention.

(Example) Example 1 A porous polyethylene film having a three-dimensional network structure obtained by the method described in JP-A-55-131028 was processed using an electron accelerator (acceleration voltage 1.5 MeV, electron beam current 1 mA). The sample was irradiated with 1 OOKGy under a nitrogen atmosphere, immersed in a 50% aqueous acrylic acid solution (containing 0.25 wt% Mohr's salt) in which dissolved oxygen had been reduced to 0.1 ppm or less, and reacted at 25°C for 1 hour. As a result, a membrane with a graft ratio of 63% was obtained. The cation exchange capacity of this membrane is 4°7
milliequivalents/gram polymer.

Using this membrane, membrane area 100cnl, filtration pressure 1kg/
Raw water with Ca (fine particles of 0.2 u or more 104″/CC%
Na'? A filtration test was conducted.

As a result, the water permeability was 9001/r after 8 hours of water flow.
rr i+r-atm, the removal rate of fine particles and sodium ions was 100%.

On the other hand, for comparison, when the reaction was carried out in the same manner as above except that the reaction temperature was changed to 70°C, the viscosity of the reaction liquid increased 10 minutes after the start of the reaction, and the pores of the porous membrane were blocked after the reaction was completed. The film became transparent.

When this membrane was subjected to a filtration test in the same manner as described above, the amount of water permeation was 1% or less of that in the above example.

Example 2 The same membrane as in Example 1 was prepared at 10 Mrad in the same manner as in Example 1.
Electron beam irradiation, dissolved oxygen 0. It was immersed in styrene monomer of 1 ppm or less and reacted at 25° C. for 1 hour. As a result, a membrane with a grafting rate of 67% was obtained.

This was reacted in a saturated solution of anhydrous sulfuric acid in dioxane and dichloroethane at 5°C for 18 hours to sulfonate it. The resulting membrane had a cation exchange capacity of 3.5 meq/g polymer. When this membrane was subjected to a filtration test in the same manner as in Example 1, the average water permeation rate was 8001 after 8 hours of water flow.
/m-hr-atm, 6 particles and the sodium ion removal rate was 100%.

On the other hand, for comparison, the reaction was carried out in the same manner as above except that a porous membrane (average pore diameter: 0.1 micron) obtained by a stretching method was used as the membrane, and a membrane with a graft ratio of 55% was obtained. This membrane was sulfonated in a manner similar to that described above, resulting in a cation exchange capacity of 3.0 milliequivalents/gram polymer. When this membrane was subjected to a filtration test in the same manner as in Example 1, the water permeation rate after 8 hours of water flow was 501/m2.
-hr・atm, and the sodium ion removal rate is 10
The particle removal rate was 80%. As a result of observing this membrane with a scanning electron microscope, it was confirmed that some of the straight pores were blocked, and that the pore size had expanded and the pore size distribution had expanded due to swelling during the reaction.

(Effects of the Invention) According to the present invention, it is possible to impart ion selective adsorption performance to a porous polymer membrane without impairing filtration performance,
Composite functional materials with excellent chemical and physical properties can be provided.

Claims (6)

[Claims] (1) A method for producing a separation functional material, which comprises graft-polymerizing a monomer containing a cation exchange group or a monomer having a functional group that can be converted into a cation exchange group onto a porous substrate. (2) The manufacturing method according to claim 1, wherein the porous base material is a porous polymer membrane having communicating pores with a three-dimensional network structure. (3) The manufacturing method according to claim 2, wherein the porous polymer membrane is made of an olefin-based or halogenated olefin-based polymer. (4) Claim 1, characterized in that the monomer is a hydrocarbon-based or halogen-containing hydrocarbon-based monomer having a sulfonic acid group, a carboxylic acid group, a phenolic hydroxyl group, or an alkali metal salt thereof. Manufacturing method described (5) The production method according to claim 1, wherein the graft polymerization comprises a step of irradiating the base material with ionizing radiation, and a subsequent step of causing the monomer to contact and react with the base material. (6) The production method according to claim 5, characterized in that the catalytic reaction is carried out in a range of 15°C to 50°C.