JP3513965B2 - Fouling-resistant porous membrane and method for producing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

The present invention is used for the purpose of filtration separation of proteins, colloids, bacteria, etc. in various separation processes such as food industry, biotechnology, ultrapure water production, wastewater treatment, recovery of valuable materials and artificial organs. The present invention relates to a filtration membrane and a manufacturing method thereof.

[0002]

2. Description of the Related Art The biggest problem in the filtration and separation process used in the above-mentioned fields is that the substances contained in the stock solution such as filtration substances, such as proteins, are adsorbed on the surface of the membrane and are deposited on the membrane surface. That is, it causes so-called fouling (contamination) that forms a new adhesion layer, and causes a decrease in membrane permeation flux (flux) and fractionation characteristics. The permeation flux of a fouled membrane often continues to drop for days until it stabilizes. Larger pressures and membrane areas are required to maintain the initial permeation flux, which increases system fabrication and operation costs,
Furthermore, problems such as membrane cleaning cost and reduced work efficiency arise. Further, in fields such as food and biotechnology, when fouling occurs, microorganisms propagate on the surface of the membrane rich in nutrients, which poses a safety and health problem.

On the other hand, fouling due to adsorption of a filtering substance (a substance that permeates a membrane) can occur not only on the membrane surface but also inside the membrane (for example, in an asymmetric membrane, also referred to as a porous support layer or a sponge layer). . In such a case, not only the filtration rate is lowered, but also the quantitative loss of the target filtration substance (especially in the case of a small amount) may become very large. For example, when a protein is separated and purified from a cell culture medium, cells are blocked by the membrane (cannot permeate through the membrane), the protein permeates through the membrane, and then a trace amount of the target substance in the protein is further isolated by chromatography or the like. It uses a refining mechanism. In this case, since the area of the wall surface of the inner sponge layer of the membrane is much larger than the surface area of the membrane (several hundred times to several thousand times), the adsorption amount of the protein by the membrane is much larger in the inner sponge layer.

Similarly, when a membrane is used for recovering valuable materials or for blood tests, a method is usually used in which useful substances are purified by passing through the membrane and unnecessary substances are removed without passing through the membrane. . Also in this case, useful substances (especially in the case of a small amount) are adsorbed on the wall surface of the sponge structure portion while passing through the membrane, and the quantitative loss of the filtration substance increases. Especially in the case of blood tests, etc., the accuracy of the tests and the reliability of the results are affected.

In order to reduce the inconvenience caused by the adsorption of the filtration substance on the membrane, it is common practice to make the membrane hydrophilic. Chemical Engineering Vol. 58, No. 1, p. 59 (1
994), a method for making a hydrophobic film hydrophilic by immersing it in a surfactant is proposed. However, in this method, the surfactant has no chemical bond with the membrane material and is merely attached to the surface of the material. If such a membrane is used for filtration, the surfactant will be eluted again in the filtrate and, conversely, will contaminate the filtrate.

Japanese Unexamined Patent Publication (Kokai) No. 62-258707 discloses a (wet) film forming method in which a low molecular weight polyethylene glycol (PEG400, liquid form) is added to a dimethylformamide solution of polyethersulfone. Also in this method, since there is no chemical bond between polyethylene glycol and polyether sulfone, there is a high possibility that liquid polyethylene glycol will be eluted during filtration. Especially when filtration is performed under conditions of high temperature, the membrane is likely to swell, and polyethylene glycol is more easily eluted. As the polyethylene glycol elutes, not only does the filtrate become contaminated, but the hydrophilicity of the membrane gradually decreases. Also,
High-molecular-weight polyethylene glycol cannot be used in this method because solid-state (molecular weight of 1000 or more) polyethylene glycol does not dissolve in polar solvents such as dimethylformamide and N-methylpyrrolidone. In addition, the N-methylpyrrolidone used in this method is a chemical regulation report (Chemical Regulation Repo
rt), p.1119, Sept. 24, 1993, it is reported that there is a great risk of reproductive and developmental disorders due to skin contact and absorption through the skin.

In Japanese Patent Laid-Open No. 3-4924, alkoxypolyethylene glycol is produced by bringing a regenerated cellulose hollow fiber membrane prepared in advance into contact with an alkoxypolyethylene glycol monocarboxylic acid to cause an esterification reaction of the carboxylic acid with a hydroxyl group on the membrane surface. There has been proposed a method of graft-polymerizing the above with a membrane. However, this method can be applied only to a film composed of a polymer having a hydroxyl group such as regenerated cellulose, resulting in poor durability of the film. In addition, this film-forming method requires many steps such as post-polymerization graft polymerization and post-washing subsequent to the production of the film, resulting in low productivity and high cost.

On the other hand, Japanese Patent Application Laid-Open No.
Japanese Patent No. 233 discloses a method for producing an asymmetric porous membrane by irradiating an energy beam after forming a mixed solution of a monomer and / or oligomer and a solvent into a membrane. No distinction is made about the adsorption or fouling resistance to proteins, etc.) and the fouling resistance between the monomers or oligomers used.

[0009]

During filtration, it is possible to reduce the adsorption of substances blocked by the membrane on the membrane surface and the adsorption of substances passing through the membrane on the wall surface of the sponge structure of the membrane (fouling resistance). In order to increase the above), it is necessary to introduce a functional group capable of reducing the adsorptivity into the entire film. From the viewpoint of improving the fouling resistance, it is preferable that the amount of the functional group introduced is large unless the strength of the film is reduced. Further, in order to prevent the functional group from being separated from the material, it is necessary to chemically bond the functional group to the molecule of the membrane material, and it is ideal that the functional group is covalently bonded.

Accordingly, the present invention provides a porous membrane which solves at least one of improving fouling resistance, preventing the elimination of functional groups, and having excellent durability, and the types of functional groups and their introduction. It is an object of the present invention to provide a method for producing a porous membrane having excellent fouling resistance, the amount of which can be adjusted more broadly and easily.

[0011]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above problems, and as a result, completed the present invention.

That is, the present invention is composed of a (meth) acrylic polymer having a cross-linked structure containing a (meth) acrylic oligomer having a polyethylene glycol structural unit as an essential component, and the content of the polyethylene glycol structural unit is 2 to 60. The present invention provides a fouling-resistant porous membrane characterized by being in a weight percentage, and a method for producing the same. The term "(meth) acrylic" as used herein means methacrylic or acrylic. Hereinafter, these are collectively described as (meth) acrylic.

The porous membrane of the present invention comprises a (meth) acrylic polymer having a crosslinked structure. This polymer contains a (meth) acrylic oligomer having a polyethylene glycol structural unit and other (meth) acrylic monomers and / or oligomers as main components.

Examples of the (meth) acrylic oligomer having a polyethylene glycol structural unit used in the present invention include ethylene glycol such as diethylene glycol (meth) acrylate, pentaethylene glycol (meth) acrylate and nonaethylene glycol (meth) acrylate. Oligomer (meth) acrylate, methoxydiethylene glycol (meth) acrylate, methoxytriethylene glycol (meth) acrylate, methoxytetraethylene glycol (meth) acrylate, methoxynonaethylene glycol (meth) acrylate, methoxytrieicosa ethylene glycol (meth) Acrylate, methoxy 30 ethylene glycol (meth) acrylate, 2 (2-ethoxyethoxy)
Of alkoxy ethylene glycol oligomers such as ethyl (meth) acrylate, ethoxytriethylene glycol (meth) acrylate, ethoxytetraethylene glycol (meth) acrylate, ethoxynonaethylene glycol (meth) acrylate, ethoxytrieicosa ethylene glycol (meth) acrylate Phenoxyethylene glycol oligomer (meth) acrylates such as (meth) acrylate, phenoxytetraethylene glycol (meth) acrylate, phenoxyhexaethylene glycol (meth) acrylate, phenoxy 30 ethylene glycol (meth) acrylate, methylphenoxydecaethylene glycol (meth) ) Acrylate, nonylphenoxyheptadeca ethylene glycol (meth) acrylate (Meth) acrylates of substituted phenoxyethylene glycol oligomers such as, monofunctional oligomers such as diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, nonaethylene glycol di (meth) acrylate, tetradeca ethylene glycol di ( (Meth) acrylate, trieicosa ethylene glycol di (meth) acrylate, 2,2-bis [4- (meth) acryloxypolyethoxy) phenyl] propane (that is, polyethylene glycol-modified bisphenol A di (meth) acrylate), etc. Examples thereof include bifunctional oligomers and trifunctional oligomers such as polyethylene glycol-modified trimethylolpropane tri (meth) acrylate. The monofunctional, bifunctional and trifunctional as used herein refer to the number of acryloyl groups.

When a monofunctional oligomer is used,
General formula (1)

[0016]

Embedded image _{CH 2 = CR 1 CO (OCH} 2 CH 2) nOR 2 (1) (R 1 is a hydrogen atom or a methyl group, R ₂ is a hydrogen atom or a hydrocarbon group having 1 to 15 carbon atoms However, n is 2 to 1
00 is an integer. However, n is the number of carbon atoms of R ₂ or more. )

Those represented by are preferably used. The hydrocarbon group having 1 to 15 carbon atoms referred to here may be aliphatic or aromatic, and may have an unsaturated bond. An alkyl group and an aromatic alkyl group are preferred. Polyethylene glycol group "(-OCH ₂ CH ₂ -)
In order to sufficiently exert the effect of introducing “n”, that is, “polyethylene glycol structural unit”, the number n of polyethylene glycol groups is preferably “n ₂ ≧ R ₂ carbon number”. The fouling resistance is improved even in the case of "n <R ₂ carbon number", but the improvement rate is lower than in the case of "n ₂ ≥R ₂ carbon number".

When a bifunctional oligomer is used,
General formula (2)

[0019]

Embedded image _{CH 2 = CR 1 CO (OCH} 2 CH 2) nOCOCR 1 = CH 2 (2) ( same as R _1, n of the definition the definition of the general formula (1))

Those represented by are preferred. General formula (1)
In both (2), the number of n is more preferably 2 to 50.

The selection of the (meth) acrylic oligomer having a polyethylene glycol structural unit is determined by the required fouling resistance of the porous membrane, the kind of the filtering substance and the like. For example, in order to obtain a film having excellent fouling resistance against water-soluble polymers and proteins,
Although a trifunctional or higher functional oligomer can be used, a bifunctional oligomer is preferably used, and a monofunctional oligomer is more preferably used. As the (meth) acrylic oligomer having a polyethylene glycol structural unit, the general formulas (1) and (2) can be used alone or in combination, and the general formula (1) is preferably used alone. .

The content of the polyethylene glycol structural unit is determined by the required fouling resistance of the porous membrane, membrane strength and the like. Usually, the higher the content of the polyethylene glycol structural unit is, the more the fouling resistance of the film is improved, but on the other hand, the film also tends to swell, and the film strength tends to decrease in a wet state. In order to maintain a good balance between the fouling resistance effect of the film and the film strength, the content of the polyethylene glycol structural unit needs to be 2 to 60% by weight based on the weight of all the polymerizable resin components. , 5 to 50
Weight% is preferable, and 7-25 weight% is more preferable. The content of the polyethylene glycol structural unit can be easily adjusted by the addition amount of the (meth) acrylic oligomer having the polyethylene glycol structural unit and the degree of polymerization (n) of the polyethylene glycol structural unit in the oligomer. The content of the polyethylene glycol structural unit here is a value obtained by dividing the weight of the polyethylene glycol group in the (meth) acrylic oligomer having the polyethylene glycol structural unit by the weight of the total polymerizable resin component.

The content of the polyethylene glycol structural unit can be appropriately adjusted within the above range depending on the properties of the filtration solution and the like. For example, a membrane for filtering an aqueous solution of a substance having strong adsorptivity such as protein. When manufacturing
The content of the polyethylene glycol structural unit should be as high as possible. On the other hand, in applications such as the production of ultrapure water in which the concentration of the adsorbing substance in the stock solution is low, this content need not be as high as in the former case.

The other (meth) acrylic monomer and / or oligomer used in the present invention may be a single component or a mixed component as long as it has a polyfunctional component, and also contains a monofunctional component. However, there is no particular limitation as long as it has a crosslinked structure when irradiated with energy rays.

Examples of polyfunctional (meth) acrylic monomers include 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, and 2,2'-bis [4- (meth ) Acryloyloxypolypropyleneoxyphenyl] propane, bisphenol A di (meth) acrylate, bis ((meth) acryloxyethyl) hydroxyethyl isocyanurate,
1,3-butylene glycol di (meth) acrylate,
Dicyclopentanyl di (meth) acrylate, neopentyl glycol di (meth) acrylate, bifunctional monomers such as methoxylated cyclohexyl di (meth) acrylate, trimethylolpropane tri (meth) acrylate, trimethylolethane tri (meth) acrylate ,
Pentaerythritol tri (meth) acrylate, tris ((meth) acryloxyethyl) isocyanurate,
Such as trifunctional monomers, pentaerythritol tetra (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, etc. tetrafunctional monomers, dipentaerythritol monohydroxypenta (meth) acrylate and other pentafunctional monomers, dipentaerythritol hexa ( Hexafunctional monomers such as (meth) acrylate may be mentioned.

As the polyfunctional (meth) acrylic oligomer, for example, an oligomer which can be polymerized by irradiation with energy rays and has two or more (meth) acrylic groups in the molecule having a weight average molecular weight of 500 to 20,000 is preferably used. , Specifically, acrylic acid ester or methacrylic acid ester of epoxy resin, acrylic acid ester or methacrylic acid ester of polyester resin, acrylic acid ester or methacrylic acid ester of polyether resin, acrylic acid ester or methacrylic acid ester of polybutadiene resin, Examples thereof include polyurethane resins having an acrylic group or a methacrylic group at the molecular end.

In order to impart strength and rigidity to the film,
The (meth) acrylic polymer having a crosslinked structure preferably contains a cyclic structural unit, and the content of the cyclic structural unit in the (meth) acrylic polymer having a crosslinked structure is preferably 5 to 50% by weight. More preferably 7 to 30% by weight. The content of the cyclic structural unit here is a value obtained by dividing the weight of the cyclic structural portion by the weight of the total polymerizable resin component. The cyclic structure referred to herein means a 4- to 6-membered cyclic structure, that is, an aromatic structure, an alicyclic structure, a heterocyclic structure, a polycyclic structure, or a ladder structure. In order to allow the (meth) acrylic polymer having a crosslinked structure to contain a cyclic structure, a polyfunctional monomer and / or oligomer containing a cyclic structure in its molecule can be used. Examples of polyfunctional monomers and / or oligomers having a cyclic structural unit include ethylene oxide-modified bisphenol A di (meth) acrylate, ethylene oxide-modified bisphenol S di (meth) acrylate, allylated cyclohexyl di (meth) acrylate, methoxylated cyclohexyl. Di (meth) acrylate, bis (acryloxyethyl)
Examples thereof include hydroxyethyl isocyanurate, tris (acryloxyethyl) isocyanurate, caprolactone-modified tris (acryloxyethyl) isocyanurate, tris (methacryloxyethyl) isocyanurate, and dicyclopentanyl di (meth) acrylate.

Functional groups other than the polyethylene glycol structural unit can be introduced into the porous membrane of the present invention (eg, hydroxyl group, sulfonic acid group, P, Si, F, etc.).
The porous membrane of the present invention is not particularly limited as to the kind of the membrane as long as it is a membrane having pores communicating from one side of the membrane to the other side, for example, isotropic in which the pore diameter is constant in the thickness direction of the membrane. It may be a porous membrane or an asymmetric porous membrane whose pore diameter changes in the thickness direction of the membrane. The asymmetric porous membrane refers to a membrane composed of a dense layer and a porous support layer supporting the dense layer. The dense layer referred to here means a layer having fine pores, and the porous support layer means a layer having pores larger than those of the dense layer. The dense layer may be present on one surface of the film, may be present on both surfaces, or may be present inside the film. For example, the middle part of both surfaces (when viewed from the cross section of the membrane)
A membrane in which a dense layer is present in the film and the porous support layer spreads toward both surfaces also belongs to the category of the present invention.

The membrane of the present invention has a pore size of 0.0005 to 20 μm, although the isotropic porous membrane varies depending on the object of separation.
Is preferred. In the case of the asymmetric membrane, the dense layer has pores having a pore diameter of 0.0005 to 20 μm that are permeable to a liquid, and these pores communicate with the pores of the porous support layer portion. . Pore diameter of dense layer is 0.0005 μm
In the case of ˜0.015 μm, it has a molecular weight fractionation ability, that is, it is possible to separate ions, low molecular weight substances or high molecular weight substances dissolved in a liquid from a liquid, or from a mixed solution of a high molecular weight substance and a low molecular weight substance. Can separate low molecular weight substances. The fact that the pore size of the dense layer is 0.015 μm or less can be determined by a filtration test of substances such as proteins.

The pore diameter of the dense layer is 0.02 μm to 20 μm.
In the case of m, a high molecular substance, a low molecular substance or ions dissolved in a liquid can be passed. The fact that the pore diameter of the dense layer is 0.02 μm or more can be determined by a filtration test of substances such as cells, and the fact that it is 20 μm or less can be determined by electron microscope observation. The pore diameter of the porous support layer is preferably 0.1 μm or more and 20 μm or less.
If it is smaller than 0.1 μm, the filtration rate will be extremely reduced, and
When it is larger than 0 μ, the strength of the film is extremely reduced.

The shape of the pores of the porous membrane of the present invention is not particularly limited, but, for example, when the gap between the spherical domains in the structure in which the spherical polymer domains are connected to each other is a communicating hole, For example, the polymer may form a network structure.

The shape of the porous membrane of the present invention is not particularly limited, and examples thereof include flat membranes, hollow fiber membranes, tubular membranes, beads and capsules. Further, the present invention provides (Production Method 1) containing a (meth) acrylic oligomer having a polyethylene glycol structural unit and other polyfunctional (meth) acrylic monomer and / or oligomer as essential components, and A phase separation agent that does not gelate the crosslinked polymer that is compatible with the resin component (A) that polymerizes and crosslinks, and that is formed by irradiating the resin component (A) with energy rays. After shaping a uniform polymerizable solution (I) containing B) as a main component,
A method for producing a crosslinked polymer by irradiating with energy rays, and then removing the phase separating agent (B), wherein the content of the polyethylene glycol structural unit in the resin component (A) is 2 to 60% by weight. And a method for producing a fouling-resistant porous membrane, characterized in that (Process 2) a (meth) acrylic oligomer having a polyethylene glycol structural unit and another polyfunctional (meth) acrylic monomer and / or oligomer A resin component (A) containing as an essential component and capable of being polymerized and crosslinked by irradiation with energy rays
And these resin components (A) are compatible with each other.
A uniform polymerizable solution (II) containing as a main component a phase separation agent (B) which does not gelate the crosslinked polymer produced by irradiating the crosslinked polymer with the energy ray and a solvent (C) which gelates the crosslinked polymer (II). ) Is shaped, then irradiated with an energy beam to form a crosslinked polymer, and then the phase separation agent (B) and / or the solvent (C) is removed, and in the resin component (A) The content of the polyethylene glycol structural unit is 2 to 60% by weight, and relates to a method for producing a fouling-resistant porous membrane.

The resin component (A) used in the production methods 1 and 2 includes the above-mentioned (meth) acrylic oligomer having a polyethylene glycol structural unit and the above-mentioned other polyfunctional (meth) acrylic monomer and / or oligomer. It is an essential component, and it is polymerized and crosslinked by irradiation with energy rays. The resin component (A) may contain a monofunctional (meth) acrylic monomer or an oligomer as long as the resin component (A) is crosslinked by irradiation with energy rays.

The (meth) acrylic oligomer having a polyethylene glycol structural unit is preferably an oligomer represented by the following general formula (1) and / or (2).

[0035]

Embedded image _{CH 2 = CR 1 CO (OCH} 2 CH 2) nOR 2 (1) CH 2 = CR 1 CO (OCH 2 CH 2) nOCOCR 1 = CH 2 (2) (R 1 is a hydrogen atom or a methyl group And R ₂ is a hydrogen atom or a hydrocarbon group having 1 to 15 carbon atoms, provided that n is 2 to 1
00 is an integer. However, n is the number of carbon atoms of R ₂ or more. ) Preferred values for n and R _{2 are} as described above.

The content of the polyethylene glycol structural unit in the resin component (A) is 2 to 60%, preferably 5
~ 50%. In order to improve the fouling resistance, it is preferable that the content of the polyethylene glycol structural unit is high, but if it is too high, the film is swollen and the durability becomes poor.

The selection of other polyfunctional monomers and / or oligomers is determined by the required properties of the porous membrane, such as heat resistance, solvent resistance, swelling resistance, pore size, membrane strength and flexibility. . Generally, membranes containing polyethylene glycol units tend to be softer and weaker than membranes that do not. Therefore, for example, in order to obtain a film having excellent heat resistance, strength, and rigidity, trifunctional or higher functional monomers and / or oligomers are selected, and aromatic, alicyclic, dicyclic, polycyclic structures are used. It is preferable to select a monomer and / or oligomer containing a cyclic structure composed of a 4- to 6-membered ring such as a ladder structure. The polyfunctional (meth) acrylic monomer and / or oligomer having a cyclic structure is preferably one containing 20 to 70% by weight, more preferably 30 to 60% by weight of a cyclic structural unit in the monomer or oligomer. Can be used.

In order to obtain the above-mentioned excellent properties such as heat resistance, the polyfunctional (meth) having a cyclic structure contained in the other polyfunctional (meth) acrylic monomer and / or oligomer. The content of the acrylic monomer and / or oligomer is preferably 10 to 100% by weight, more preferably 20 to 50% by weight.

As the resin component (A), in addition to the above, any polymerizable monomer and / or oligomer can be added. As the polymerizable monomer and / or oligomer, a (meth) acrylic monomer and / or oligomer is suitable. By adding a monomer and / or oligomer having a functional group, a functional group other than polyethylene glycol can be easily introduced into the porous membrane.

The resin component (A) is compatible with the resin component (A), and the phase separating agent (B) does not gelate the crosslinked polymer produced by irradiating the resin component (A) with energy rays. And can be mixed and used as a uniform polymerizable solution (I). It is also possible to use the polymerizable solution (I) as a polymerizable solution (II) by containing a solvent (C) for gelling the polymer produced from the resin component (A).

After shaping these polymerizable solutions, they are polymerized by irradiation with energy rays to remove all of the phase separation agent (B) and / or the solvent (C), thereby forming an isotropic porous membrane or an asymmetric membrane. A porous membrane is obtained. In addition, phase separation agent (B)
And / or by partially volatilizing the solvent (C), polymerization is carried out by irradiation with energy rays, and the remaining phase separation agent (B) and / or solvent (C) is removed to obtain a pore size distribution in the thickness direction of the membrane. An asymmetric porous membrane having is obtained.

First, the production method 1 using the polymerizable solution (I) will be described. The phase-separating agent (B) is a resin component (A) containing a (meth) acrylic oligomer having a polyethylene glycol structural unit used in the present invention and other polyfunctional (meth) acrylic monomers and / or oligomers as essential components. Can be dissolved uniformly, and the polymer formed from these oligomers and / or monomers does not gel, and is substantially inert to energy rays.

The term "gelling" as used herein is a concept defined for a crosslinked polymer and refers to a phenomenon of swelling that occurs when the crosslinked polymer is immersed in a solvent that dissolves a non-crosslinked polymer having the same chemical structure. In such gelling,
Depending on the degree of cross-linking of the cross-linked polymer, generally 20% or more by weight of the polymer can be contained in the polymer.

The kind of the phase separating agent (B) can be changed depending on the kind of the resin component (A). In addition, phase separation agent (B)
May have a single composition or a mixture.
For example, when a polyethylene glycol acrylate-based oligomer represented by the formula (1) and / or (2) and a polyurethane resin having an acrylic group as another polyfunctional acrylic-based oligomer are used, the phase separation agent (B) may be decane. Mixtures of fatty acid esters such as methyl acid, dialkyl ketones such as diisobutyl ketone, liquid polyethylene glycol, polyethylene glycol monoesters, polyethylene glycol monoethers, water and water-soluble solvents such as alcohols (eg propanol, butanol). Liquids, polymers such as polyvinylpyrrolidone and cellulose acetate, and the like can be preferably used.

Among these, the use of a mixed liquid of water and a water-soluble solvent as the solvent (B) produces the same resin component (A).
Is preferable because a film with high fouling resistance can be obtained. At this time, the proportion of water in the mixed liquid of water and the water-soluble solvent is generally preferably 10 to 80%, more preferably 20 to 40%. The type of water-soluble solvent is preferably selected appropriately depending on the mixing ratio of water. That is, the more water there is, the more water-soluble solvent the resin component (A)
It is only necessary to select one that is highly compatible with.

The phase separating agent (B) depends on the shape of the membrane (for example, flat membrane, hollow fiber, beads, capsules, etc.), the type of oligomer and / or monomer contained in the polymerizable solution (I), and the necessity. It can be appropriately selected depending on the viscosity of the polymerizable solution, the solubility of the polymer and other additives, the pore size and the shape of the pores required for the membrane, and the like. The less compatible the layer separating agent (B) is with the resin component (A), the larger the pore size.

When ultraviolet rays are used as the energy rays, the phase separating agent (B) preferably has a small ultraviolet ray absorption. The amount of the phase separation agent (B) added is in consideration of the balance between the porosity (permeation flux) or molecular weight fractionation characteristics of the membrane and the membrane strength, etc., and the total polymerizable resin component (having a polyethylene glycol structural unit ) Acrylic oligomer and other polyfunctional (meth) acrylic monomer and / or oligomer) 1 part by weight to 1 part by weight is preferable, and 1 to 3 parts by weight is more preferable. The larger the amount of the phase separating agent (B) added, the larger the pore size.

In the production method 1 of the present invention, the phase separation agent (B)
There are roughly two times of removal of. One is to shape the polymerizable solution (I) and then irradiate it with an energy ray to remove all (B) from the crosslinked polymer. The other is to shape the polymerizable solution (I), volatilize a part of (B), and then irradiate an energy ray to form a crosslinked polymer, and remove the remaining (B). . In the former case, not only an asymmetric membrane but also an isotropic porous membrane can be produced, but in the latter case, only an asymmetric membrane can be produced.

As a removing method, when removing before polymerization, a method of applying a stream of an inert gas such as nitrogen to the shaped polymerizable solution (I), or particularly in an atmosphere of nitrogen without applying a stream of air Part of it may be volatilized by any method such as leaving it to dry for several seconds to several tens of seconds, or irradiating with infrared rays.
When the boiling point of (B) is low, the temperature of the airflow or the atmosphere is raised, but the airflow may be speeded up, and the amount to be removed can be appropriately adjusted. The pore size of the membrane can be controlled by the amount removed.

In the case of the production method in which a part of the phase separation agent is volatilized, there is a correlation between the volatilization of the phase separation agent and the degree of the asymmetric structure, and the degree of the asymmetric structure depends on the molecular weight fractionation ability and the filtrate. It has a correlation with the amount of permeation (also called a membrane permeation flux or flux). Therefore, the selection of the boiling point of the phase separation agent can be an important factor that determines the filtration performance of the resulting porous membrane. One example of the selection of the boiling point of the phase separation agent is to evaporate a part of the phase separation agent at a temperature of room temperature or below, or the velocity of an air stream blown to the polymerizable solution to volatilize a part of the phase separation agent. When the value is small or when it is necessary to volatilize a part of the phase separating agent within an extremely short time, a phase separating agent having a boiling point of 80 ° C. or lower is preferably used. Further, when a heated air stream is blown onto the polymerizable solution, and when a part of the phase separation agent is volatilized over a certain period of time, a phase separation agent having a boiling point of 60 ° C. or higher is preferably used. Further, the phase separating agent may be a mixture of two or more kinds.

After the completion of the polymerization by irradiation with energy rays, it is necessary to remove the phase separation agent and the solvent by evaporation and / or washing whether or not the phase separation agent is partially removed before the polymerization. For cleaning, use a phase separation agent, solvent,
Unreacted monomers and / or oligomers, those capable of sufficiently dissolving the photopolymerization initiator (eg, hexane,
Ethanol, water, etc.) can be used. Further, the cleaning may be a plurality of steps using a plurality of cleaning agents.

Next, the production method 2 using the polymerizable solution (II) will be described. In the production method 2, the solvent (C) is appropriately added to the polymerizable solution (I) depending on the compatibility between the resin component (A) and the phase separating agent (B), the boiling point of the phase separating agent (B), etc. I
The film forming method is the same as the case where the polymerizable solution (I) is used as I). At this time, the phase separation agent (B) that can be used is the same as the phase separation agent described in the production method 1, but unlike the case of the production method 1, the polymerization component (A) and the phase separation agent (B) are It does not have to be dissolved, and the polymerizable solution (II) may be a uniform solution.

The solvent (C) used in the present invention is capable of uniformly dissolving a (meth) acrylic oligomer having a polyethylene glycol structural unit and other polyfunctional (meth) acrylic monomers and / or oligomers. Any polymer may be used as long as it gels a polymer formed from these oligomers and / or monomers. For example, acetone, methyl ethyl ketone,
Ethyl acetate, methanol, ethanol, 2-methoxyethanol, dimethylformamide, dimethylacetamide and the like can be preferably used. The solubility and boiling point can be appropriately selected depending on the type of oligomer and / or monomer, required molecular weight fractionation ability, membrane permeation flux, required degree of asymmetric structure, type of phase separation agent, and the like.

When the polymerizable solution contains a solvent (C),
The phase separation agent (B) is expanded by expanding the solubility control range.
Also, as a result of widening the selection range of the polymerizable monomer, oligomer, and additive, it becomes easy to improve the film performance and to manufacture a film having characteristics according to the purpose of use. Further, by adjusting the combination of the boiling points of the phase separating agent (B) and the solvent (C), it becomes easy to form the dense layer at any position such as the gas phase side, the support side or the inside of the membrane. The selection of the boiling point of the solvent (C) can be an important factor that determines the filtration performance of the resulting porous membrane, like the phase separation agent (B).
It is necessary to select on the same basis as the phase separation agent (B). Further, there is often a correlation between the solubility of the solvent (C) and the molecular weight fractionation performance of the obtained porous membrane. To give an example, a highly soluble solvent can be used to obtain a membrane capable of filtering a substance having a relatively small molecular weight.

The inventors of the present invention have obtained a porous film obtained by using water as the phase separating agent (B) even when the same resin component (A) is used in the polymerizable solution (II). It has been found that the fouling resistance of is improved. At this time, when the ratio of water to the total of the phase separation agent (B) (that is, water) and the solvent (C) is increased, a film with high fouling resistance can be obtained, while when the ratio of water is too high, The obtained film has a poor strength in a wet state. The ratio of water to the total of the phase separating agent (B) (that is, water) and the solvent (C) is generally preferably 10 to 80%, and 20 to 40%.
Is more preferable.

When the content of water as the phase separating agent (B) changes, the compatibility with the resin component (A) changes, and the pore size of the resulting porous membrane also changes. Generally, the larger the water content, the larger the pore size. In order to improve the anti-fouling property while keeping the pore diameter of the obtained porous film constant, the purpose can be achieved by selecting the kind of the solvent (C). That is, if the water content is large, a solvent having a high compatibility with the resin component (A) may be selected as the solvent (C).

The amount of the solvent (C) added to the total polymerizable resin component (A) was variously studied as a result of various studies in consideration of the properties of the polymerizable solution, the structure of the membrane, the filtration performance and the like. 1 to
A range of 4.0 parts by weight is preferred.

The method for removing the phase separating agent (B) and / or the solvent (C) from the polymerizable solution (II) before or after the polymerization is the same as the case of using the phase separating agent (B) alone,
When part of (B) or (C) is to be selectively removed, it can be carried out by selecting one having an appropriate boiling point.

Additives and the like can be added to the polymerizable solutions (I) and (II), but it is necessary to remove them at the time of washing after the polymerization. As the shaping method for forming the polymerizable solution in the form of a thin film in the production methods 1 and 2, on a support,
A method of applying a flat film by a roll coating method, a doctor blade method, a spin coating method, a spray method or the like can be used. On the other hand, a hollow fiber thin film is also produced by extruding a polymerizable solution together with a core agent (for example, gas, water, liquid polyethylene glycol, liquid polypropylene glycol, etc.) into a hollow fiber shape from a double cylindrical nozzle and passing it through an ultraviolet irradiation area. be able to.

The energy rays used in the production methods 1 and 2
For electron beam, γ ray, X ray, ultraviolet ray, visible ray, etc.
Can be Above all, the device and the ease of handling
It is desirable to use ultraviolet rays. The intensity of ultraviolet light
10 to 500 mW / cm ², Preferably 50 to 20
0 mW / cm²Is desirable. UV rays as energy rays
The purpose of increasing the polymerization rate when using visible light
It is also possible to add a photopolymerization initiator to the polymerizable solution.
Is. Also, UV irradiation is performed in an inert gas atmosphere.
It is possible to further increase the polymerization rate by
It The photopolymerization initiator is a monomer or oligomer that is exposed to light.
May or may not chemically bond with
May be

As the photopolymerization initiator that can be mixed with the polymerizable solutions (I) and (II) of the present invention, p-tert-butyltrichloroacetophenone, 2,2'-diethoxyacetophenone, 2-hydroxy-2- Acetophenones such as methyl-1-phenylpropan-1-one; ketones such as benzophenone, 4,4′-bisdimethylaminobenzophenone, 2-chlorothioxanthone, 2-methylthioxanthone, 2-isopropylthioxanthone; benzoin, benzoinmethyl Benzoin ethers such as ether, benzoin isopropyl ether, and benzoin isobutyl ether; and benzyl ketals such as benzyl dimethyl ketal and hydroxycyclohexyl phenyl ketone.

Electron beams are also preferred energy beams that can be used in the present invention. When the electron beam is used, it is not affected by the presence or absence of absorption of ultraviolet rays by the phase separation agent (B) and other additives, so that the selection range of these is broadened and the film production rate is further improved. Further, since a polymerization initiator is not necessary, it can be easily applied to applications where this residue is a problem.

The irradiation of energy rays can be carried out, for example, by directly irradiating the shaped polymerizable solution with the energy rays on the upper surface of the membrane in the case of a flat membrane and around the membrane in the case of a hollow fiber membrane.
As the surrounding atmosphere, it is preferable to use an inert gas such as nitrogen.

Since the fouling-resistant porous membrane of the present invention is excellent in fouling resistance, strength, heat resistance and chemical resistance, it can be effectively applied to reverse osmosis membranes, ultrafiltration membranes, microfiltration membranes and the like. It is possible.

[0065]

The present invention will be described in more detail with reference to the following examples, but the scope of the present invention is not limited thereto.

[Definition of Measurement Items] The definitions and measurement conditions for the measurement items in the following examples are as follows. (1) Membrane permeation flux (flux or flux) The amount (liter) of water (or an aqueous solution of a filtration substance) that permeates a 1-square meter membrane for 1 hour with a pressure difference of 1 kg / cm ² . The unit of membrane permeation flux is L / m ² -h-kg-cm ^-2 .

(2) Fouling index (FI) First, the water flux_H2O1), and protein water soluble
Liquid flux _H2Oprotein) and water flux
(Flux_H2O2) is measured, and as shown in equation (3), the flux is
 H₂O2 and flux H₂Ratio with O1 (ie protein filtration
Fouling index before and after)
(FI).

[0068]

FI (%) = (flux _H2O2 / flux _H2O1 ) × 100 (3) FI = 100% means that the membrane is not fouling at all. If the flux changes with time, the first measured value (called the initial value) is used.

(3) Rejection rate (%) 100 ml of an aqueous protein solution having a predetermined concentration (Cb) was filtered with a batch type filter (SM-165-26, Sartorius Co.) with stirring (having a membrane set). The protein concentration (Cp) of the filtrate was measured with an ultraviolet-visible spectrophotometer, and (4)
The rejection rate (%) is calculated from the formula.

[0070]

## EQU00002 ## Rejection rate (%) = (1-Cp / Cb) .times.100 (4) (4) After measuring the water flux of the heat-resistant porous membrane, 1 in the free length state in an autoclave at 120.degree. After steam heat treatment for an hour, the water flux is measured again under the same conditions, and the flux reduction rate is calculated.

(5) Consolidation The pressure difference was 3 kg / cm ² , and the change with time of the water flux was measured.
The decrease rate of the flux after 60 minutes with respect to the flux immediately after pressurization is calculated.

Example 1 (Preparation of Polymerizable Solution) Methoxynonaethylene glycol acrylate (brand name NK ester AM-90G, Shin-Nakamura Chemical Co., Ltd.) 7 parts, number average molecular weight 2000, averaged in 1 molecule. Urethane acrylate oligomer having 3 acryloyl groups (trade name Unidic V-426
3, Dainippon Ink and Chemicals, Inc.) 70 parts, dicyclopentanyl diacrylate (trade name: Kayarad R-684, Nippon Kayaku Co., Ltd.) 23 parts, Irgacure-184 (ultraviolet polymerization initiator, Ciba Geigy) 2 parts, solvent 100 parts of isopropyl alcohol as (C) and 40 parts of distilled water as the phase separation agent (B) were uniformly mixed to obtain a polymerizable solution 1.

(Preparation of Asymmetric Porous Membrane) The polymerizable solution 1 was applied onto a glass plate with a film applicator to a thickness of 2
It was applied so as to have a thickness of 00 μm. A part of the solvent (C) was volatilized by allowing this glass plate to stand in a nitrogen stream for 30 seconds, and then the glass plate was irradiated with a 100 mw / cm ² ultraviolet lamp for 10 seconds. When the obtained milky white film was immersed in water for each glass plate, the film spontaneously peeled off from the glass plate after about 5 seconds. This membrane was washed with ethanol to wash out unreacted monomers and oligomers and a polymerization initiator, and then washed again with water. Dry the washed membrane thoroughly under reduced pressure,
A porous film 1 having a gloss (dense layer) on the glass plate side and no gloss on the side in contact with the nitrogen stream was obtained. As a result of observing the porous film with a scanning electron microscope (SEM), the glossy side has a pore diameter of about 0.02 μm, and the matte side has about 2
It was found to have a pore size of μm. Further, the portion having a smaller pore size than the observation of the cross section was only an extremely thin layer on the glass plate side (glossy side), and the thickness thereof was 1 μm or less.

(Evaluation of Fouling Resistance) As the filter, an SM-165-26 type ultrafiltration device (volume 200 ml, membrane diameter 47 mm) manufactured by Sartorius was used. As the protein aqueous solution, a 0.1% water (or physiological saline) solution of bovine serum albumin (hereinafter abbreviated as albumin) having a molecular weight of 67,000 was used. Filtration was performed at room temperature with a pressure difference of 2 kg / cm ² . As a result, the content of polyethylene glycol structural unit (CPEG, wt%), albumin rejection, water flux before and after albumin filtration (flux _H2O 1, flux _H2O 2),
Table 1 shows the fouling index values (FI,%). Although the amount of polyethylene glycol units was smaller than that of the porous membrane of Example 10, which was produced under the condition that methyl decanoate was used as the phase separating agent (B) instead of water and the solvent (C) was not used. It can be seen that the film exhibits high fouling resistance.

(Evaluation of heat resistance and pressure densification) The manufactured films were cut and subjected to a heat resistance test and a pressure densification test. Table 2 shows the reduction rate of the water flux due to the sterilization treatment at 120 ° C for 1 hour in the autoclave. Pressure difference 3kg / c
m ² , when measuring the water flux at room temperature for 60 minutes,
Table 3 shows the flux reduction rate after 60 minutes from immediately after the start of measurement.

Example 2 (Preparation of Polymerizable Solution) 30 parts of methoxynonaethylene glycol acrylate (trade name NK ester AM-90G, Shin-Nakamura Chemical Co., Ltd.), urethane acrylate oligomer (trade name Unidick V-4263, 52.5 parts by Dainippon Ink and Chemicals, Inc., dicyclopentanyl diacrylate (trade name: Kayarad R-684, Nippon Kayaku Co., Ltd.) 1
7.5 parts, Irgacure-184 (UV polymerization initiator,
Ciba Geigy) 2 parts, solvent (C) 100 parts isopropyl alcohol, phase separator (B) distilled water 41
The parts were uniformly mixed to obtain a polymerizable solution 2.

(Preparation of Asymmetric Porous Membrane) By the same operation as in Example 1 except that the polymerizable solution 2 was used as the polymerizable solution, the glass plate side was glossy and the side in contact with the nitrogen stream side was contacted. Obtained an asymmetric porous membrane 2 having no gloss. SE
The result of observation with M was the same as that of Example 1.

(Evaluation of Fouling Resistance) The results are shown in Table 1. (Evaluation of heat resistance and pressure densification) The manufactured film was cut into pieces and subjected to a heat resistance test and a pressure densification test. Table 2 shows the reduction rate of the water flux due to the sterilization treatment at 120 ° C for 1 hour in the autoclave. Table 3 shows the reduction rate of the flux after 60 minutes from immediately after the start of measurement when the water flux was measured at room temperature for 60 minutes with a pressure difference of 3 kg / cm ² .

Example 3 (Preparation of Polymerizable Solution) Methoxypolyethylene glycol (n = 30) methacrylate (trade name light ester 041)
MA, Kyoeisha Chemical Co., Ltd.) 10 parts, epoxy acrylate oligomer having two acryloyl groups in one molecule (trade name epoxy ester 3002A, Kyoeisha Chemical Co., Ltd.) 6
7.5 parts, 2,2-bis [4- (acryloxydiethoxy) phenyl] propane (trade name New Frontier B
PE-4, Daiichi Kogyo Seiyaku Co., Ltd.) 22.5 parts, Irgacure-184 (ultraviolet polymerization initiator) 2 parts, and 160 parts of diisobutyl ketone as a phase separating agent (B) are uniformly mixed to obtain a polymerizable solution 3. It was

(Preparation of Asymmetric Porous Membrane) Example 1 was repeated except that the polymerizable solution 3 was used as the polymerizable solution and that part of the phase separating agent (B) was removed instead of the solvent (C). By a similar operation, an asymmetric porous film 3 having a gloss on the glass plate side and a gloss on the side in contact with the nitrogen stream side was obtained. The result of the SEM observation was almost the same as that of Example 1 except that the pore size on the glossy surface side was about 0.01 μm.

(Evaluation of Fouling Resistance) The results are shown in Table 1.

Example 4 (Preparation of Polymerizable Solution) Nonaethylene glycol methacrylate (Blenmer PE-350, trade name, NOF Corporation)
10 parts, polyester acrylate oligomer having an average of 4 acryloyl groups in one molecule (trade name Aronix M-8060, Toagosei Kagaku Kogyo Co., Ltd.) 67.5
Part, 1,6-hexanediol diacrylate (trade name: Kayarad HDDA, Nippon Kayaku Co., Ltd.) 22.5 parts, Irgacure 184 (Ciba Geigy Co., Ltd.) 2 parts, and 30 parts of methyl decanoate and laurin as a phase separating agent (B). 120 parts of methyl acidate and 5 parts of acetone as the solvent (C) were uniformly mixed to obtain a polymerizable solution 4.

(Preparation of Asymmetric Porous Membrane) Same as Example 1 except that the polymerizable solution 4 was used as the polymerizable solution and the phase separating agent (B) and the solvent (C) were partially removed. By the operation, an asymmetric porous film 4 having a gloss on the glass plate side and a gloss on the side in contact with the nitrogen stream side was obtained. SE
The result of observation by M was almost the same as that of Example 3.

(Evaluation of fouling resistance) The results are shown in Table 1.

Example 5 (Preparation of Polymerizable Solution) 10 parts of nonylphenoxyheptadecaethylene glycol acrylate (trade name New Frontier N177E, Dai-ichi Kogyo Seiyaku Co., Ltd.), propylene oxide-modified trimethylolpropane triacrylate (trade name Aronix) M-310, Toagosei Chemical Industry Co., Ltd.) 90 parts, Irgacure 184 (Ciba Geigy)
2 parts, 100 parts of isopropyl alcohol as (C),
As (B), 38.5 parts of distilled water was uniformly mixed to obtain a polymerizable solution 5.

(Preparation of Asymmetric Porous Membrane) By the same operation as in Example 1 except that the polymerizable solution 5 was used as the polymerizable solution, the glass plate side had gloss and the side in contact with the nitrogen stream side was treated. Obtained an asymmetric porous film 5 having no gloss. SE
The result of observation by M was almost the same as that of Example 3.

(Evaluation of fouling resistance) The results are shown in Table 1.

Example 6 (Preparation of Polymerizable Solution) 20 parts of tetradecaethylene glycol diacrylate (trade name NK ester A-600, Shin-Nakamura Chemical Co., Ltd.), 2,2-bis [4- (acryloxy) Diethoxy) phenyl] propane (trade name New Frontier BPE-4, Daiichi Kogyo Seiyaku Co., Ltd.) 80 parts, Irgacure 184 (Ciba Geigy) 2 parts, and polyethylene glycol monolaurate 2 as a phase separating agent (B)
00 parts and 10 parts of acetone as the solvent (C) were uniformly mixed to obtain a polymerizable solution 6.

(Preparation of Asymmetric Porous Membrane) The same as Example 1 except that the polymerizable solution 6 was used as the polymerizable solution and the phase separating agent (B) and the solvent (C) were partially removed. By the operation, an asymmetric porous film 6 having a gloss on the glass plate side and a gloss on the side in contact with the nitrogen stream side was obtained. SE
The result of observation by M was almost the same as that of Example 1.

(Evaluation of fouling resistance) The results are shown in Table 1.

Example 7 (Preparation of Polymerizable Solution) 10 parts of methoxynonaethylene glycol acrylate (trade name NK ester AM-90G, Shin-Nakamura Chemical Co., Ltd.), urethane acrylate oligomer (trade name Unidick V-4263, Dainippon Ink and Chemicals, Inc.) 67.5 parts, dicyclopentanyl diacrylate (trade name: Kayarad R-684, Nippon Kayaku Co., Ltd.) 2
2.5 parts, Irgacure-184 (UV polymerization initiator,
Ciba Geigy) 2 parts and polyethylene glycol (n = 2) mono-p-nonylphenyl ether 200 parts as a phase separation agent (B) were uniformly mixed to obtain a polymerizable solution 7.

(Preparation of Asymmetric Porous Membrane) The polymerizable solution 7 was applied onto a glass plate with a film applicator to a thickness of 2
It was applied so as to have a thickness of 00 μm. This glass plate was exposed to a 10 mW / cm ² ultraviolet lamp under a nitrogen stream for 10 minutes.
Irradiated for 2 seconds. The obtained milky white film was immersed in petroleum ether for each glass plate, and after about 5 seconds, the film spontaneously peeled off from the glass plate. This membrane was washed with ethanol to obtain unreacted monomers and oligomers, polymerization initiators, phase separation agents (B)
Was washed out and finally washed with water. The washed film was sufficiently dried under reduced pressure to obtain a porous film 7 having a gloss (dense layer) on the glass plate side and no gloss on the side in contact with the nitrogen stream.

The results of the SEM observation were almost the same as in Example 3. (Evaluation of fouling resistance) The results are shown in Table 1.

Example 8 (Preparation of Polymerizable Solution) 15 parts of 2 (2-ethoxyethoxy) ethyl acrylate (trade name: Biscoat 190, Osaka Organic Chemical Industry Co., Ltd.), propylenoxide-modified trimethylolpropane triacrylate ( Product name Aronix M
-310, Toagosei Chemical Industry Co., Ltd.) 85 parts, Irgacure-184 (ultraviolet polymerization initiator, Ciba Geigy) 6 parts,
100 parts of polyvinylpyrrolidone (MW: about 10,000, Tokyo Chemical Industry Co., Ltd.) as a phase separating agent (B) and 350 parts of N, N-dimethylacetamide as a solvent (C) were uniformly mixed to obtain a polymerizable solution 8.

(Preparation of Asymmetric Porous Membrane) The polymerizable solution 8 was applied onto a glass plate with a film applicator to a thickness of 2
It was applied so as to have a thickness of 00 μm. This glass plate was irradiated with a 100 mw / cm ² ultraviolet lamp under a nitrogen stream for 10 seconds. When the obtained milky white film was immersed in water for each glass plate, the film spontaneously peeled off from the glass plate after about 5 seconds. The membrane was thoroughly washed with water to remove the phase separation agent (B) and the solvent (C), washed with ethanol, washed out of unreacted monomers and oligomers and polymerization initiator, and finally washed again with water. . The washed film was sufficiently dried under reduced pressure to obtain a porous film 8 having gloss (dense layer) on the glass plate side and no gloss on the side in contact with the nitrogen stream. SEM
The result of the observation by the above was almost the same as that of Example 3.

(Evaluation of fouling resistance) The results are shown in Table 1.

Example 9 (Preparation of Polymerizable Solution) Nonylphenoxydecaethylene glycol acrylate (trade name Aronix M-11)
1, Toa Gosei Kagaku Kogyo Co., Ltd., 10 parts, urethane acrylate (trade name Unidic V-4263, Dainippon Ink & Chemicals Co., Ltd.) 67.5 parts, dicyclopentanyl diacrylate 22.5 parts, Irgacure 184 (Ciba Geigy) 2 parts, isopropyl alcohol 100 as (C)
Parts and 40 parts of distilled water as (B) were uniformly mixed to obtain a polymerizable solution 9.

(Preparation of Asymmetric Porous Membrane) By using the polymerizable solution 9 as the polymerizable solution, the same operation as in Example 1 was performed so that the glass plate side had gloss and the side in contact with the nitrogen stream side had the gloss. An asymmetric porous film 9 having no gloss was obtained. The results of observation by SEM were almost the same as in Example 1.

(Evaluation of fouling resistance) The results are shown in Table 1. It was found that when n <R ₂ in the general formula (1), the effect of improving the fouling resistance is low.

Example 10 (Preparation of Polymerizable Solution) A uniform polymerizable solution 10 was obtained in the same manner as in Example 1 except that 190 parts of methyl decanoate was used as the phase separating agent (B).

(Preparation of Asymmetric Porous Membrane) By using the polymerizable solution 10 as the polymerizable solution, the same operation as in Example 1 was performed, and the glass plate side had gloss and the side in contact with the nitrogen stream side was An asymmetric porous membrane 10 having no gloss was obtained. SE
The result of observation by M was almost the same as that of Example 1.

(Evaluation of Fouling Resistance) The results are shown in Table 1. Comparing this comparative example with Example 1, even if a polymerizable solution having the same composition except for the phase separating agent (b) was used, the fouling resistance of the membrane was improved by using water as the phase separating agent (B). It can be seen that can be greatly improved.

[Embodiment 11] In this embodiment, it is shown that when a (meth) acrylic acid oligomer (A) having no cyclic structure is used, the film becomes inferior in pressure densification.

(Preparation of Polymerizable Solution) Methoxypolyethylene glycol 400 methacrylate (NK ester M-90G, as (meth) acrylic acid oligomer (A))
Shin-Nakamura Chemical Co., Ltd. 72 parts, 1,6-hexanediol diacrylate 18 parts, Irigacure 184 (Ciba Geigy) 2 parts as a photopolymerization initiator, phase separation agent (B) 41 parts water, solvent ( As C), 100 parts of 2-propanol was mixed and spun to obtain a uniform polymerizable solution 11.

(Preparation of Asymmetric Porous Membrane) By using the polymerizable solution 11 as the polymerizable solution, the same operation as in Example 1 was carried out so that the glass plate side had gloss and the nitrogen stream side was in contact with the side. An asymmetric porous film 11 having no gloss was obtained. S
The results of observation by EM were almost the same as in Example 12.

(Evaluation of fouling resistance) The results are shown in Table 1. (Heat resistance, pressure densification test) Cut the manufactured film,
A heat resistance test and a pressure densification test were performed. Table 2 shows the reduction rate of the water flux due to the sterilization treatment at 120 ° C for 1 hour in the autoclave. Pressure difference 3kg / cm ² , 6 at room temperature
Table 3 shows the reduction rate of the flux after 60 minutes from the time immediately after the start of the measurement when the water flux was measured for 0 minutes.

[Comparative Example 1] In this comparative example, an example of a porous film made of an acrylic polymer containing no special hydrophilic monomer (or oligomer) is shown.

(Preparation of Polymerizable Solution) Polyester acrylate oligomer (trade name Aronix M-8060,
Toa Gosei Kagaku Kogyo Co., Ltd.) 75 parts, 1,6-hexanediol diacrylate 25 parts, Irgacure 184 (Ciba Geigy) 2 parts, as phase separation agent (B) 30 parts of methyl decanoate and 105 parts of methyl laurate, solvent As (C), 5 parts of acetone was uniformly mixed to obtain a polymerizable solution 10.

(Preparation of Asymmetric Porous Membrane) Operation similar to that of Example 1 except that the polymerizable solution 10 was used as the polymerizable solution and the phase separating agent (B) and a part of the solvent (C) were removed. Thus, an asymmetric porous film 10 having a gloss on the glass plate side and a gloss on the side in contact with the nitrogen gas stream side was obtained. S
The results of observation by EM were almost the same as in Example 3.

(Evaluation of fouling resistance) The results are shown in Table 1. The fouling index was as small as 61%.

[Comparative Example 2] A similar fouling resistance test was carried out using a commercially available polyethersulfone ultrafiltration membrane (trade name OMEGA FILTER OM010047, FILTRON CORPORATION) that was subjected to a hydrophilization treatment (treatment method unknown). I went. The results are shown in Table 1.

[Comparative Example 3] The same fouling resistance test was conducted using a commercially available polysulfone ultrafiltration membrane (trade name NTU-3150, Nitto Denko Corporation). The results are shown in Table 1.
It was shown to. A heat resistance test and a pressure densification test were performed using the same film. Table 2 shows the reduction rate of the water flux due to the sterilization treatment at 120 ° C for 1 hour in the autoclave. Table 3 shows the reduction rate of the flux after 60 minutes from immediately after the start of measurement when the water flux was measured at room temperature for 60 minutes with a pressure difference of 3 kg / cm ² .

[0113]

[Table 1]

[0114]

[Table 2] CPEG: content of polyethylene glycol structural unit n: number of repeating units of polyethylene glycol (1 formula,
2 formula) Carbon number of R ₂ : number of carbon atoms or hydrogen atom (see 1 formula)

[0115]

[Table 3]

[0116]

[Table 4]

[0117]

INDUSTRIAL APPLICABILITY The porous membrane having the polyethylene glycol structural component of the present invention can remarkably reduce the adsorption of the filtration substance on the membrane surface or the adsorption of the filtration substance on the membrane porous support part, and high water solubility. Excellent fouling resistance to molecules, especially proteins. Since polyethylene glycol is chemically bonded to the polymer, polyethylene glycol does not elute during use. Since the membrane material has a crosslinked structure, it has excellent strength, heat resistance, chemical resistance, durability, and the like.

The manufacturing method of the present invention is different from conventional porous film manufacturing methods such as a wet film forming method using a polar solvent for a linear polymer (eg, N-methylpyrrolidone)
Wide selection of oligomers, easy design of cross-linking density and cross-linking structure, easy introduction of functional groups into the membrane, and simple production process, compared to conventional hydrophilic treatment by post-treatment. It is characterized by high productivity and high production rate because polymerization and phase separation are completed substantially instantaneously during film formation. In addition, N-, which is highly dangerous and difficult to treat waste liquid,
The use of high boiling polar solvents such as methylpyrrolidone can be avoided.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI // C08L 33:06 C08L 33:06 (58) Fields surveyed (Int.Cl. ⁷ , DB name) B01D 71/40 C08F 299 / 02 C08J 9/26

Claims (14)

(57) [Claims] 1. A (meth) acrylic polymer having a crosslinked structure containing a (meth) acrylic oligomer having a polyethylene glycol structural unit as an essential component, and having a polyethylene glycol structural unit content of 2 to 60% by weight. A fouling resistant porous membrane characterized by being present. 2. A (meth) acrylic oligomer having a polyethylene glycol structural unit is represented by the following general formula (1):
And / or (2) ## STR1 ## _{CH 2 = CR 1 CO (OCH} 2 CH 2) nOR 2 (1) CH 2 = CR 1 CO (OCH 2 CH 2) nOCOCR 1 = CH 2 (2) ( wherein , R ₁ is a hydrogen atom or a methyl group, R ₂ is a hydrogen atom or a hydrocarbon group having 1 to 15 carbon atoms, and n is 2 to 1
00 is an integer. However, n is the number of carbon atoms of R ₂ or more. The porous membrane according to claim 1, which is a (meth) acrylic oligomer represented by the formula (1). 3. The porous membrane according to claim 1, wherein the content of the polyethylene glycol structural unit contained in the (meth) acrylic polymer having a crosslinked structure is 5 to 50% by weight. 4. The porous membrane according to claim 1, wherein the (meth) acrylic polymer having a crosslinked structure contains a cyclic structural unit together with a polyethylene glycol structural unit. 5. A method according to claim 1-4 porous membrane is asymmetric membrane
The porous membrane according to any one of 1. 6. A (meth) acrylic oligomer having a polyethylene glycol structural unit and another polyfunctional (meth) acrylic monomer and / or oligomer are contained as essential components, and they are polymerized and crosslinked by irradiation with energy rays. And a phase separation agent (B) which is compatible with the resin component (A) and does not gelate the crosslinked polymer produced by irradiating the resin component (A) with energy rays. A method for producing a uniform polymerizable solution (I) containing as a main component, shaping the same, irradiating with energy rays to obtain a crosslinked polymer, and then removing the phase separating agent (B) The method for producing a fouling resistant porous membrane, wherein the content of the polyethylene glycol structural unit in the component (A) is 2 to 60% by weight. 7. The production method according to claim 6 , wherein after the polymerizable solution (I) is shaped, a part of the phase separation agent (B) is volatilized and then an energy ray is irradiated. 8. Phase separation agent (B) The method according to claim 6 or 7, wherein a mixed solution of water and a water-soluble solvent. 9. A (meth) acrylic oligomer having a polyethylene glycol structural unit and another polyfunctional (meth) acrylic monomer and / or oligomer are contained as essential components, and they are polymerized and cross-linked by irradiation with energy rays. A resin component (A) which is compatible with the resin component (A), and a phase separation agent (B) which is compatible with the resin component (A) and does not gelate the crosslinked polymer produced by irradiating the resin component (A) with energy rays, A uniform polymerizable solution (II) containing, as a main component, a solvent (C) for gelling a crosslinked polymer is shaped and then irradiated with energy rays to form a crosslinked polymer, and then a phase separation agent ( B) and / or a solvent (C) is removed, and the content of the polyethylene glycol structural unit in the resin component (A) is 2 to 60% by weight. A method for producing a fouling resistant porous membrane. 10. After shaping the polymerizable solution (II), a part of the phase separating agent (B) and / or the solvent (C) is volatilized,
The method according to claim 9, further comprising irradiating with energy rays. 11. Phase separation agent (B) are provided methods for producing the porous membrane of claim 9 also <br/> 10 wherein the water. 12. A (meth) acrylic oligomer having a polyethylene glycol structural unit is represented by the following general formula (1) and / or (2): CH ₂ ═CR ₁ CO (OCH ₂ CH ₂ ) nOR ₂ ( _{1) CH 2 = CR 1 CO} (OCH 2 CH 2) nOCOCR 1 = CH 2 (2) ( wherein, R ₁ represents a hydrogen atom or a methyl group, R ₂ represents a hydrogen atom or a hydrocarbon of 1 to 15 carbon atoms And n is 2 to 1
00 is an integer. However, n is the number of carbon atoms of R ₂ or more. The method for producing a porous membrane according to any one of claims 8 to 13 , which is a (meth) acrylic oligomer represented by the formula (4). 13. The content of the polyethylene glycol structural units in the resin component (A), the production method of the porous membrane according to any one of claims 6-11 which is 5 to 50 wt%. 14. Other polyfunctional (meth) acrylic monomer and / or oligomer of any of claims 6-13 are those containing a polyfunctional (meth) acrylic monomer and / or oligomer having a cyclic structure A method for producing a porous membrane according to item 1.