JP6712717B2 - Method for producing polyvinyl chloride porous filtration membrane for water treatment - Google Patents
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Description
本発明は、耐ファウリング性と耐薬品性を併せ持つ水処理用ポリ塩化ビニル製多孔質濾過膜の製造方法に関する。 The present invention relates to a method for producing a polyvinyl chloride porous filtration membrane for water treatment, which has both fouling resistance and chemical resistance.
最近、限外濾過、精密濾過、逆浸透などの水処理用多孔質濾過膜は、例えば、飲料水製造、上下水道処理、あるいは廃液処理など、多くの産業分野で利用されている。このような水処理用多孔質濾過膜の中で、限外濾過膜や精密濾過膜は水質の浄化などに多用されている。しかし水処理用多孔質濾過膜は疎水性が高く、ファウリングし易いことが問題となっている。ファウリングとは、原水に含まれるファウラントと呼ばれる原因物質、例えば、難溶性成分や、蛋白質、多糖類などの高分子の溶質、コロイド、微小固形物、微生物などが膜に沈着して透過流速を低下させる現象であり、膜性能低下の主要原因として知られている。
このような蛋白質や微生物を原因とするファウリングに対し、比較的効果の高い多孔質濾過膜の製造方法として、例えば、蛋白質や微生物などのファウラントを吸着抑制できる素材を、多孔質濾過膜に保持または吸着する方法が提案されている。
Recently, porous filtration membranes for water treatment such as ultrafiltration, microfiltration and reverse osmosis have been used in many industrial fields such as drinking water production, water and sewage treatment, and waste liquid treatment. Among such water treatment porous filtration membranes, ultrafiltration membranes and microfiltration membranes are widely used for purification of water quality. However, the problem is that the porous membrane for water treatment is highly hydrophobic and easily fouled. Fouling is a causative substance called foulant contained in raw water, for example, sparingly soluble components, solutes of polymers such as proteins and polysaccharides, colloids, minute solids, microorganisms, etc. are deposited on the membrane to increase the permeation flow rate. It is a phenomenon that deteriorates the film performance and is known as the main cause of the deterioration of the membrane performance.
As a method for producing a porous filtration membrane that is relatively effective against fouling caused by such proteins and microorganisms, for example, a material capable of suppressing adsorption of foulants such as proteins and microorganisms is retained in the porous filtration membrane. Alternatively, a method of adsorption is proposed.
例えば特許文献１には、２−メタクリロイルオキシエチルホスホリルコリンを重合した共重合体の溶液を多孔質濾過膜表面にコーティングし、ファウラントの吸着を抑制する方法が提案されている。
特許文献２には２−メタクリロイルオキシエチルホスホリルコリンを重合した共重合体の溶液を凝固浴に入れ、製膜時に膜に共重合体を取り込む方法が提案されている。
また、特許文献３には、特定の２−メタクリロイルオキシエチルホスホリルコリンを重合した共重合体の溶液をポリスルホンと混合することで製膜する製造方法が提案されている。
For example, Patent Document 1 proposes a method of coating a solution of a copolymer obtained by polymerizing 2-methacryloyloxyethylphosphorylcholine on the surface of a porous filtration membrane to suppress the adsorption of foulants.
Patent Document 2 proposes a method in which a solution of a copolymer obtained by polymerizing 2-methacryloyloxyethylphosphorylcholine is placed in a coagulation bath and the copolymer is incorporated into the film during film formation.
Further, Patent Document 3 proposes a production method of forming a film by mixing a solution of a copolymer obtained by polymerizing specific 2-methacryloyloxyethylphosphorylcholine with polysulfone.
しかしながら、特許文献１では、水処理用多孔質濾過膜に後処理として２−メタクリロイルオキシエチルホスホリルコリンを重合した共重合体をコーティングするため、当該共重合体の保持が十分ではなく、経日による耐ファウリング性が低下するおそれがある。特許文献２では、２−メタクリロイルオキシエチルホスホリルコリンを重合した共重合体を凝固浴中に含有させるため、水処理用多孔質濾過膜中に保持されない共重合体が多く存在し、当該共重合体の使用効率が低く、製造コストが高いという問題がある。また、特許文献３では、水処理時におけるファウリング抑制効果は確認されておらず、水処理用多孔質濾過膜の製造方法としての検討はなされていない。また、水処理用途では次亜塩素酸ナトリウムなどの薬品で洗浄することも想定されるが、特許文献３の技術では、それら薬品に対する耐性（耐薬品性）について考慮されていない。 However, in Patent Document 1, since the porous filtration membrane for water treatment is coated with a copolymer obtained by polymerizing 2-methacryloyloxyethylphosphorylcholine as a post-treatment, the retention of the copolymer is not sufficient, and the resistance to aging The fouling property may be reduced. In Patent Document 2, since the copolymer obtained by polymerizing 2-methacryloyloxyethylphosphorylcholine is contained in the coagulation bath, there are many copolymers that are not retained in the water treatment porous filtration membrane. There are problems of low efficiency of use and high manufacturing cost. Further, in Patent Document 3, the effect of suppressing fouling at the time of water treatment has not been confirmed, and no investigation has been made as a method for producing a porous filtration membrane for water treatment. Moreover, although it is assumed that cleaning is performed with a chemical such as sodium hypochlorite for water treatment applications, the technique of Patent Document 3 does not consider resistance to these chemicals (chemical resistance).
そこで、本発明は、ファウリングを効果的に抑制して透水率に優れるとともに、ファウリングが生じた時の薬品等による洗浄後の透水率の回復にも優れる、水処理用ポリ塩化ビニル製多孔質濾過膜を高効率で製造する方法を提供することを課題とする。 Therefore, the present invention is a polyvinyl chloride porous for water treatment, which effectively suppresses fouling and is excellent in water permeability, and is also excellent in recovering water permeability after washing with chemicals or the like when fouling occurs. An object of the present invention is to provide a method for producing a high quality filtration membrane with high efficiency.
本発明者らは、上記の問題点を解決すべく鋭意検討を重ねた結果、水処理用ポリ塩化ビニル製多孔質濾過膜の製造に当たり、該濾過膜の原料として、特定のホスホリルコリン基およびポリオキシアルキレン基を有する共重合体、並びにポリ塩化ビニルを用い、当該原料を含有する製膜原液を使用して特定の方法によって多孔質濾過膜を製造する方法を見出し、本発明を完成するに至った。 The present inventors have conducted extensive studies to solve the above problems, and as a result, in producing a polyvinyl chloride porous filtration membrane for water treatment, as a raw material of the filtration membrane, a specific phosphorylcholine group and polyoxy group are used. By using a copolymer having an alkylene group and polyvinyl chloride, a method for producing a porous filtration membrane by a specific method using a membrane-forming stock solution containing the raw material was found, and the present invention has been completed. ..
すなわち、本発明によれば、共重合体（Ｐ）１〜５質量％、及びポリ塩化ビニル１０〜２０質量％を含有する製膜原液を調製する製膜原液調製工程（ａ）と、前記製膜原液をノズルまたはスリットを通して膜状に吐出させる吐出工程（ｂ）と、吐出される前記膜状の製膜原液を凝固液に浸漬させ、多孔質膜を形成させる製膜工程（ｃ）と、を有し、前記共重合体（Ｐ）は、下記式（１）のモノマー１０〜４０モル％と、下記式（２）のモノマー６０〜９０モル％との、重量平均分子量が１０，０００〜１，０００，０００の共重合体である、水処理用ポリ塩化ビニル製多孔質濾過膜の製造方法が提供される。
（式中、Ｒ１は水素原子又はメチル基を示し、Ｒ２及びＲ３はそれぞれ独立に炭素数１〜４のアルキレン基を示し、Ｒ４、Ｒ５及びＲ６はそれぞれ独立に炭素数１〜４のアルキル基を示す。）
(In the formula, R 1 represents a hydrogen atom or a methyl group, R 2 and R 3 each independently represent an alkylene group having 1 to 4 carbon atoms, and R 4 , R 5, and R 6 each independently represent 1 carbon atom. ~ 4 alkyl groups are shown.)
本発明の製造方法によれば、ポリ塩化ビニル製の多孔質膜に上記共重合体（Ｐ）が、該多孔質膜から容易に脱離できないように保持された水処理用ポリ塩化ビニル製多孔質濾過膜を製造することができる。すなわち、繰返しの洗浄や過激な薬品洗浄によっても共重合体（Ｐ）がポリ塩化ビニル製多孔質膜から溶出することがなく、ファウリング抑制効果が長期間維持できる水処理用ポリ塩化ビニル製多孔質濾過膜（以後、単に、本発明の濾過膜と称することがある）を製造することができる。 According to the production method of the present invention, a polyvinyl chloride porous membrane for water treatment, in which the above-mentioned copolymer (P) is retained in a polyvinyl chloride porous membrane so as not to be easily desorbed from the porous membrane. A quality filtration membrane can be manufactured. That is, the copolymer (P) does not elute from the polyvinyl chloride porous membrane even after repeated cleaning or extreme chemical cleaning, and the fouling suppressing effect can be maintained for a long period of time. A high quality filtration membrane (hereinafter sometimes simply referred to as the filtration membrane of the present invention) can be manufactured.
以下本発明を詳細に説明する。
本発明の製造方法により製造できる本発明の濾過膜は、ポリ塩化ビニル製多孔質膜に共重合体（Ｐ）が強固に保持された水処理用ポリ塩化ビニル製多孔質濾過膜である。
The present invention will be described in detail below.
The filtration membrane of the present invention that can be produced by the production method of the present invention is a polyvinyl chloride porous filtration membrane for water treatment in which the copolymer (P) is firmly held on the polyvinyl chloride porous membrane.
本発明の濾過膜の製造方法は、共重合体（Ｐ）とポリ塩化ビニルを溶解させた均一透明な一相となる製膜原液を調製し、これを凝固液に浸漬して製膜させることにより、ポリ塩化ビニル製多孔質膜に共重合体（Ｐ）が強固に保持された、透水性に優れる多孔質濾過膜を製造できる点に特徴がある。ここで、強固に保持とは、濾過膜の使用時および濾過膜の洗浄時において、共重合体（Ｐ）がポリ塩化ビニル製多孔質膜から脱離しないことを意味する。 In the method for producing a filtration membrane of the present invention, a uniform and transparent one-phase membrane-forming stock solution in which a copolymer (P) and polyvinyl chloride are dissolved is prepared, and this is immersed in a coagulating solution to form a membrane. According to this, a porous filtration membrane having excellent water permeability in which the copolymer (P) is firmly held in the polyvinyl chloride porous membrane can be manufactured. Here, “hold firmly” means that the copolymer (P) is not desorbed from the polyvinyl chloride porous membrane when the filtration membrane is used and when the filtration membrane is washed.
本発明の製造方法に使用する共重合体（Ｐ）は、下記式（１）のモノマー１０〜４０モル％と、下記式（２）のモノマー６０〜９０モル％とを共重合させた、重量平均分子量が１０，０００〜１，０００，０００の共重合体である。
（式中、Ｒ１は水素原子又はメチル基を示し、Ｒ２及びＲ３はそれぞれ独立に炭素数１〜４のアルキレン基を示し、Ｒ４、Ｒ５及びＲ６はそれぞれ独立に炭素数１〜４のアルキル基を示す。）
（式中、Ｒ７は水素原子又はメチル基を示し、Ｒ８及びＲ９はそれぞれ独立に炭素数２〜４のアルキレン基を示し、Ｒ１０は水素原子又は炭素数１〜４のアルキル基を示す。ｎ及びｍはいずれも０〜１５であり、かつｎ＋ｍの値は７〜１５である。）
The copolymer (P) used in the production method of the present invention is obtained by copolymerizing 10 to 40 mol% of the monomer of the following formula (1) and 60 to 90 mol% of the monomer of the following formula (2). It is a copolymer having an average molecular weight of 10,000 to 1,000,000.
(In the formula, R 1 represents a hydrogen atom or a methyl group, R 2 and R 3 each independently represent an alkylene group having 1 to 4 carbon atoms, and R 4 , R 5, and R 6 each independently represent 1 carbon atom. ~ 4 alkyl groups are shown.)
(In the formula, R 7 represents a hydrogen atom or a methyl group, R 8 and R 9 each independently represent an alkylene group having 2 to 4 carbon atoms, and R 10 represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. (N and m are both 0 to 15 and the value of n+m is 7 to 15.)
すなわち、共重合体（Ｐ）は、下記式（３）の構造単位１０〜４０モル％、および下記式（４）の構造単位６０〜９０モル％からなる共重合体である。
（式中、Ｒ７は水素原子又はメチル基を示し、Ｒ８及びＲ９はそれぞれ独立に炭素数２〜４のアルキレン基を示し、Ｒ１０は水素原子又は炭素数１〜４のアルキル基を示す。ｎ及びｍはいずれも０〜１５であり、かつｎ＋ｍの値は７〜１５である。）
That is, the copolymer (P) is a copolymer composed of 10 to 40 mol% of structural units represented by the following formula (3) and 60 to 90 mol% of structural units represented by the following formula (4).
(In the formula, R 7 represents a hydrogen atom or a methyl group, R 8 and R 9 each independently represent an alkylene group having 2 to 4 carbon atoms, and R 10 represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. (N and m are both 0 to 15 and the value of n+m is 7 to 15.)
式（３）の構造単位が１０モル％未満で、式（４）の構造単位が９０モル％を超える場合には、実用上十分なファウリング抑制効果を示さないおそれがある。一方、式（３）の構造単位が４０モル％を超え、式（４）の構造単位が６０モル％未満の場合には、共重合体中のポリオキシアルキレン基の割合が少なくなり、ポリ塩化ビニルとの親和性が低下し、製膜原液が均一透明溶液とならずに相分離を起こすおそれがある。その結果、基本的な濾過性能の点で満足のいく濾過膜を製膜できないおそれがある。 When the structural unit of the formula (3) is less than 10 mol% and the structural unit of the formula (4) is more than 90 mol %, there is a possibility that the fouling suppressing effect is not sufficient in practical use. On the other hand, when the structural unit of the formula (3) exceeds 40 mol% and the structural unit of the formula (4) is less than 60 mol %, the proportion of the polyoxyalkylene group in the copolymer decreases and the polychlorination There is a possibility that the affinity for vinyl is lowered, and the stock solution for film formation does not become a uniform transparent solution, causing phase separation. As a result, it may not be possible to form a filtration membrane that is satisfactory in terms of basic filtration performance.
共重合体（Ｐ）の原料である式（１）のモノマーとしては、例えば、２−メタクリロイルオキシエチルホスホリルコリン（以後、ＭＰＣと略記する）、３−メタクリロイルオキシプロピルホスホリルコリン、４−メタクリロイルオキシブチルホスホリルコリン、２−メタクリロイルオキシエチル−２’−トリエチルアンモニオエチルホスフェート、２−メタクリロイルオキシエチル−２’−トリブチルアンモニオエチルホスフェートが挙げられる。入手性の点からはＭＰＣが特に好ましい。 Examples of the monomer of the formula (1) which is a raw material of the copolymer (P) include 2-methacryloyloxyethylphosphorylcholine (hereinafter abbreviated as MPC), 3-methacryloyloxypropylphosphorylcholine, 4-methacryloyloxybutylphosphorylcholine, Examples thereof include 2-methacryloyloxyethyl-2'-triethylammonioethyl phosphate and 2-methacryloyloxyethyl-2'-tributylammonioethyl phosphate. MPC is particularly preferable in terms of availability.
共重合体（Ｐ）のもう一つの原料である式（２）のモノマーの、−Ｒ８Ｏ−、−Ｒ９Ｏ−で表されるオキシアルキレン基としては、オキシエチレン基および／またはオキシプロピレン基が好ましい。ポリ塩化ビニルとの親和性が良好だからである。式（２）において、オキシアルキレン基の繰返し単位数ｎ＋ｍの値は、７〜１５であり、好ましくは９〜１３である。この範囲であれば、製膜原液を均一透明溶液として得るのに好適だからである。−Ｒ８Ｏ−および−Ｒ９Ｏ−のＲ８とＲ９の炭素数が異なる場合、−Ｒ８Ｏ−および−Ｒ９Ｏ−の各繰返し単位は、各オキシアルキレン基がブロックで結合していてもよく、ランダムに結合していてもよい。
式（２）のモノマーの具体例としては、ポリプロピレングリコールモノメタクリレート（以後、ＰＰＧＭＡと略記する）、ポリプロピレングリコールモノアクリレート、ポリ（エチレングリコール−プロピレングリコール）モノメタクリレート、ポリ（エチレングリコール−プロピレングリコール）モノアクリレート、ポリブチレングリコールモノメタクリレート、ポリブチレングリコールモノアクリレート、ポリ（エチレングリコール−テトラメチレングリコール）モノメタクリレート、ポリ（エチレングリコール−テトラメチレングリコール）モノアクリレート、ポリ（プロピレングリコール−テトラメチレングリコール）モノメタクリレート、ポリ（プロレングリコール−テトラメチレングリコール）モノアクリレートが挙げられる。入手性の点からはＰＰＧＭＡが特に好ましい。
The oxyalkylene group represented by —R 8 O— and —R 9 O— in the monomer of formula (2), which is another raw material of the copolymer (P), is an oxyethylene group and/or an oxypropylene group. Groups are preferred. This is because it has a good affinity with polyvinyl chloride. In the formula (2), the value of the number of repeating units n+m of the oxyalkylene group is 7 to 15, preferably 9 to 13. This is because if it is within this range, it is suitable for obtaining the film-forming stock solution as a uniform transparent solution. If the number of carbon atoms of -R 8 O-and -R 9 O-of R 8 and R 9 are different, -R 8 O-and -R 9 O-each repeating unit of each oxyalkylene group is bonded in block Or they may be bonded at random.
Specific examples of the monomer of the formula (2) include polypropylene glycol monomethacrylate (hereinafter abbreviated as PPGMA), polypropylene glycol monoacrylate, poly(ethylene glycol-propylene glycol) monomethacrylate, poly(ethylene glycol-propylene glycol) mono. Acrylate, polybutylene glycol monomethacrylate, polybutylene glycol monoacrylate, poly(ethylene glycol-tetramethylene glycol) monomethacrylate, poly(ethylene glycol-tetramethylene glycol) monoacrylate, poly(propylene glycol-tetramethylene glycol) monomethacrylate, Examples include poly(prolene glycol-tetramethylene glycol) monoacrylate. PPGMA is particularly preferable in terms of availability.
共重合体（Ｐ）は、ランダム共重合体、ブロック共重合体等いずれの構造であってもよく、これらの共重合体の混合物でもよい。
共重合体（Ｐ）の分子量は、ゲルパーミエーションクロマトグラフィー（ＧＰＣ）による、標準ポリメチルメタクリレートを用いて換算した重量平均分子量（Ｍｗ）で、１０，０００〜１，０００，０００であり、好ましくは１０，０００〜５００，０００である。該分子量が１０，０００未満の場合には、共重合体（Ｐ）のポリ塩化ビニル製多孔質膜への保持力が不十分で、多孔質濾過膜を製膜した後、共重合体（Ｐ）が該濾過膜から脱離し易くなるおそれがある。その結果、十分なファウリング抑制効果を示さないおそれがある。一方、分子量が１，０００，０００を超える場合は、製膜原液用溶媒に難溶となるおそれがあり、製膜原液が均一透明溶液とならずに相分離を起こすおそれがある。その結果、基本的な濾過性能の点で満足のいく濾過膜を製膜できないおそれがある。
The copolymer (P) may have any structure such as a random copolymer or a block copolymer, or may be a mixture of these copolymers.
The molecular weight of the copolymer (P) is 10,000 to 1,000,000 in terms of weight average molecular weight (Mw) calculated using standard polymethylmethacrylate by gel permeation chromatography (GPC), preferably Is 10,000 to 500,000. If the molecular weight is less than 10,000, the retention of the copolymer (P) on the polyvinyl chloride porous membrane is insufficient, and after the porous filtration membrane is formed, the copolymer (P ) May be easily desorbed from the filtration membrane. As a result, there is a possibility that a sufficient fouling suppression effect may not be exhibited. On the other hand, when the molecular weight exceeds 1,000,000, it may be difficult to dissolve in the solvent for forming a film-forming solution, and the film-forming solution may not be a uniform transparent solution and may undergo phase separation. As a result, it may not be possible to form a filtration membrane that is satisfactory in terms of basic filtration performance.
共重合体（Ｐ）の重合法としては、溶液重合、塊状重合、乳化重合、懸濁重合等公知の方法を用いることができ、例えば、式（１）のモノマーと式（２）のモノマーとを溶媒中で重合開始剤の存在下、重合反応させる方法を採用することができる。
前記重合反応に用いる溶媒としてはこれらのモノマーが溶解すればよく、具体的には、水、メタノール、エタノール、プロパノール、ｔ−ブタノール、ベンゼン、トルエン、ジメチルホルムアミド、ジメチルスルホキシド、Ｎ−メチルピロリドン、テトラヒドロフラン、クロロホルム等が挙げられ、２種以上を混合してもよい。
前記重合反応に用いる開始剤としては、通常の開始剤ならばいずれを用いてもよく、例えば、ラジカル重合の場合は脂肪族アゾ化合物や有機過酸化物を用いることができる。
As the polymerization method of the copolymer (P), known methods such as solution polymerization, bulk polymerization, emulsion polymerization and suspension polymerization can be used. For example, the monomer of the formula (1) and the monomer of the formula (2) can be used. It is possible to employ a method of carrying out a polymerization reaction in the presence of a polymerization initiator in a solvent.
As the solvent used in the polymerization reaction, these monomers may be dissolved, and specifically, water, methanol, ethanol, propanol, t-butanol, benzene, toluene, dimethylformamide, dimethylsulfoxide, N-methylpyrrolidone, tetrahydrofuran. , Chloroform and the like, and two or more kinds may be mixed.
As the initiator used in the polymerization reaction, any ordinary initiator may be used. For example, in the case of radical polymerization, an aliphatic azo compound or an organic peroxide can be used.
製膜原液中の共重合体（Ｐ）の含有量は１〜５質量％である。共重合体（Ｐ）が１質量％未満では、所望のファウリング抑制効果が得られず、共重合体（Ｐ）が５質量％を超えると、製膜原液が均一透明溶液になり難く、基本的な濾過性能の点で満足のいく濾過膜を製膜できないおそれがある。 The content of the copolymer (P) in the stock solution for film formation is 1 to 5 mass %. If the copolymer (P) is less than 1% by mass, the desired fouling suppression effect cannot be obtained, and if the copolymer (P) exceeds 5% by mass, the stock solution for film formation is difficult to be a uniform transparent solution, There is a possibility that a satisfactory filtration membrane cannot be formed in terms of effective filtration performance.
本発明の製造方法に用いるポリ塩化ビニルとしては、水処理膜用に使用できるグレードであれば特に制限なく使用できる。 The polyvinyl chloride used in the production method of the present invention can be used without particular limitation as long as it is a grade that can be used for a water treatment membrane.
製膜原液中のポリ塩化ビニルの含有量は１０〜２０質量％である。この範囲であれば、本発明の濾過膜の製膜に好適な製膜原液を得ることができるからである。 The content of polyvinyl chloride in the stock solution for film formation is 10 to 20% by mass. This is because if it is within this range, it is possible to obtain a membrane-forming stock solution suitable for forming the membrane of the present invention.
共重合体（Ｐ）とポリ塩化ビニルとの含有割合としては、ポリ塩化ビニル１００質量部に対して共重合体（Ｐ）１〜２５質量部が好ましく、１〜２０質量部がより好ましい。共重合体（Ｐ）の含有量が１質量部未満では、所望のファウリング抑制効果がえられず、２５質量部超では、ポリ塩化ビニル量が相対的に減少するため、製膜後の多孔質濾過膜の力学強度が低下するおそれがある。 The content ratio of the copolymer (P) and polyvinyl chloride is preferably 1 to 25 parts by mass, and more preferably 1 to 20 parts by mass with respect to 100 parts by mass of polyvinyl chloride. When the content of the copolymer (P) is less than 1 part by mass, the desired fouling suppressing effect cannot be obtained, and when it exceeds 25 parts by mass, the amount of polyvinyl chloride is relatively decreased, and thus the porosity after film formation is reduced. The mechanical strength of the quality filtration membrane may decrease.
共重合体（Ｐ）とポリ塩化ビニルが上記含有量範囲で製膜原液に均一に溶解していることにより、製膜時において、共重合体（Ｐ）はポリ塩化ビニル製多孔質膜中に取り込まれ、該多孔質膜から容易に脱離しないように強固に保持される。その結果、繰返しのアルカリを用いた薬品洗浄や過激な薬品洗浄によって共重合体（Ｐ）が、ポリ塩化ビニル製多孔質膜から濾液中や洗浄液中等に溶出することなく、高いファウリング抑制効果を維持することができる。 Since the copolymer (P) and polyvinyl chloride are uniformly dissolved in the stock solution for film formation within the above content range, the copolymer (P) is contained in the polyvinyl chloride porous film during film formation. It is taken in and firmly held so as not to be easily detached from the porous membrane. As a result, the copolymer (P) does not elute from the polyvinyl chloride porous membrane into the filtrate or the cleaning solution due to repeated chemical cleaning using alkali or extreme chemical cleaning, and a high fouling suppression effect can be obtained. Can be maintained.
共重合体（Ｐ）がポリ塩化ビニル製多孔質膜に強固に保持される理由としては、両者を均一透明に溶解した製膜原液を調製して製膜させることにより、共重合体（Ｐ）が単にポリ塩化ビニル製多孔質膜の表面に吸着するのではなく、共重合体（Ｐ）の一部があたかも共結晶のようにポリ塩化ビニル中に取り込まれた形で膜化するからと考えられる。 The reason why the copolymer (P) is firmly retained in the polyvinyl chloride porous membrane is that the copolymer (P) is prepared by preparing a membrane-forming stock solution in which both are uniformly and transparently dissolved to form a membrane. Is not simply adsorbed on the surface of the polyvinyl chloride porous membrane, but a part of the copolymer (P) is taken into the polyvinyl chloride like a co-crystal to form a film. To be
本発明の製膜原液用の溶媒としては、該製膜原液を凝固液中に浸漬（吐出）したときの相分離性の点でジメチルアセトアミド、ジメチルホルムアミド、ジメチルスルホキシド、およびＮ−メチルピロリドン等が好ましい。 Examples of the solvent for the film-forming stock solution of the present invention include dimethylacetamide, dimethylformamide, dimethylsulfoxide, and N-methylpyrrolidone in terms of phase separation when the film-forming stock solution is immersed (discharged) in a coagulating liquid. preferable.
製膜のための凝固液としては、膜素材である共重合体（Ｐ）およびポリ塩化ビニルを溶解しない非溶媒である水単独、あるいは水および膜素材を溶解する溶媒、例えば上記製膜原液用の溶媒の混合溶媒を使用する。
混合溶媒を使用する場合は、水と膜素材を溶解する溶媒の混合割合としては、水１００質量部に対して膜素材を溶解する溶媒１〜１０質量部が好ましい。本発明の濾過膜の製膜が良好に進行するからである。
また、製膜原液１００質量部に対して、凝固液を１，０００〜１００，０００質量部使用することが好ましい。本発明の濾過膜の製膜が良好に進行するからである。
As a coagulating liquid for film formation, water (non-solvent) that does not dissolve the copolymer (P) that is a film material and polyvinyl chloride, or a solvent that dissolves water and a film material, such as the above stock solution for film formation A mixed solvent of the above solvents is used.
When a mixed solvent is used, the mixing ratio of water and the solvent that dissolves the membrane material is preferably 1 to 10 parts by mass of the solvent that dissolves the film material with respect to 100 parts by mass of water. This is because the production of the filtration membrane of the present invention proceeds well.
Further, it is preferable to use 1,000 to 100,000 parts by mass of the coagulating liquid with respect to 100 parts by mass of the film forming stock solution. This is because the production of the filtration membrane of the present invention proceeds well.
次に、本発明の濾過膜の製造方法の詳細について説明する。
なお、本発明の製造方法によって製造し得る濾過膜の形状としては、中空糸膜状と平膜状を挙げることができる。
Next, details of the method for producing the filtration membrane of the present invention will be described.
The shape of the filtration membrane that can be produced by the production method of the present invention includes a hollow fiber membrane shape and a flat membrane shape.
１．熱誘起相分離法による中空糸膜状の本発明の濾過膜の製造方法
本発明の熱誘起相分離法では、高温で、膜素材である共重合体（Ｐ）およびポリ塩化ビニルを上記溶媒に溶解させて製膜原液を調製後、低温の凝固液（水または上記混合溶媒）で冷却することにより、膜素材の濃厚相と希薄相に相分離させる。この濃厚相からポリ塩化ビニル製多孔質膜に共重合体（Ｐ）が保持された本発明の濾過膜が析出して製膜される。
共重合体（Ｐ）は製膜される多孔質濾過膜のファウリング抑制に寄与すると共に、多孔質濾過膜の孔径制御の役割も担う。
1. Method for Producing Hollow Fiber Membrane Filtration Membrane of the Present Invention by Thermally Induced Phase Separation In the thermally induced phase separation of the present invention, the membrane material copolymer (P) and polyvinyl chloride are used in the above solvent at high temperature. After being dissolved to prepare a film-forming stock solution, the solution is cooled with a low-temperature coagulating solution (water or the above-mentioned mixed solvent) to cause phase separation into a concentrated phase and a diluted phase of the film material. From this concentrated phase, the filtration membrane of the present invention in which the copolymer (P) is retained is deposited on the polyvinyl chloride porous membrane to form a membrane.
The copolymer (P) contributes to suppressing fouling of the porous filtration membrane to be formed, and also has a role of controlling the pore size of the porous filtration membrane.
凝固液としては、下記に示す内部凝固液と外部凝固液とを使用し、内部凝固液、外部凝固液いずれも、水または上記混合溶媒を使用するが、両者は同一であってもよいし、一方が水、他方が混合溶媒であってもよく、また、混合溶媒中の溶媒の種類やその比率が異なるものであってもよい。 As the coagulating liquid, the following internal coagulating liquid and external coagulating liquid are used, and both the internal coagulating liquid and the external coagulating liquid use water or the above mixed solvent, but both may be the same. One may be water and the other may be a mixed solvent, and the types and ratios of the solvents in the mixed solvent may be different.
次に、具体的な製造工程について説明する。
（１）製膜原液調製工程（ａ）：共重合体（Ｐ）１〜５質量％、およびポリ塩化ビニル１０〜２０質量％を溶媒に添加し、５０〜２００℃に加温して溶解させ製膜原液を得る。
（２）吐出工程（ｂ）：製膜原液を２重紡糸ノズルより中空糸膜状に吐出させる。具体的には、２重紡糸ノズルへの製膜原液の供給と同時に、２重紡糸ノズルの芯部に内部凝固液を供給して吐出させる。中空糸膜の場合は、このように内部凝固液を使用するので、吐出された製膜原液の一部は本発明の濾過膜に製膜された状態となっているが、便宜上、「吐出された中空糸膜状の製膜原液」と称することとする。
（３）製膜工程（ｃ）：吐出される中空糸膜状の製膜原液を直ちに外部凝固液に浸漬させ冷却する。これによって、中空糸膜状の本発明の濾過膜の製膜を完全なものとする。外部凝固液の温度は０〜５０℃である。
以上の製造工程を採ることにより、共重合体（Ｐ）がポリ塩化ビニル製多孔質膜に強固に保持された中空糸膜状の本発明の濾過膜が形成される。
なお、外部凝固液が水または水を含む混合溶媒であることによって、共重合体（Ｐ）の側鎖部分であるホスホリルコリン基はポリ塩化ビニル中に取り込まれず、ポリ塩化ビニル多孔質膜の表面に、濾液等と接触可能なように存在することができる（下記平膜状の場合も同様）。
Next, a specific manufacturing process will be described.
(1) Film-forming stock solution preparation step (a): 1 to 5% by mass of the copolymer (P) and 10 to 20% by mass of polyvinyl chloride are added to a solvent and heated to 50 to 200° C. to be dissolved. Obtain a film forming stock solution.
(2) Discharge step (b): The stock solution for film formation is discharged as a hollow fiber film from the double spinning nozzle. Specifically, at the same time as the film forming stock solution is supplied to the double spinning nozzle, the internal coagulating liquid is supplied to and discharged from the core of the double spinning nozzle. In the case of the hollow fiber membrane, since the internal coagulation liquid is used in this manner, a part of the discharged membrane-forming raw solution is in a state of being formed on the filtration membrane of the present invention. The hollow fiber membrane-shaped stock solution".
(3) Film-forming step (c): The discharged hollow fiber membrane-shaped film-forming stock solution is immediately immersed in an external coagulating solution and cooled. This completes the production of the hollow fiber membrane-shaped filtration membrane of the present invention. The temperature of the external coagulating liquid is 0 to 50°C.
By adopting the above manufacturing steps, the hollow fiber membrane-shaped filtration membrane of the present invention in which the copolymer (P) is firmly held by the polyvinyl chloride porous membrane is formed.
In addition, since the external coagulation liquid is water or a mixed solvent containing water, the phosphorylcholine group, which is the side chain portion of the copolymer (P), is not incorporated into the polyvinyl chloride, and the surface of the polyvinyl chloride porous membrane is , And can be present so that it can come into contact with the filtrate and the like (the same applies in the case of the following flat film).
なお、製膜工程（ｃ）の後に、３０〜９５℃の温水または熱水を用いて溶媒等を除去する洗浄工程、溶媒を抽出によって除去する抽出工程、および４０〜７０℃の乾燥工程を行ってもよい。また、すぐに使用しないときはグリセリンやエタノールを含む保存液で保存すればよい。 In addition, after the film forming step (c), a washing step of removing the solvent and the like using hot water or hot water of 30 to 95° C., an extraction step of removing the solvent by extraction, and a drying step of 40 to 70° C. May be. When it is not used immediately, it may be stored in a storage solution containing glycerin or ethanol.
２．熱誘起相分離法による平膜状の本発明の濾過膜の製造方法
平膜状の濾過膜の製造に当たっては、上記１．の中空糸膜状の濾過膜の製造と同じ製膜原液用溶媒、および凝固液を使用することができる。ただし、凝固液としては、中空糸膜状の外部凝固液に対応する１種類のみを使用する。
2. Method for Producing Flat Membrane Filtration Membrane of the Present Invention by Thermally Induced Phase Separation In producing the flat membrane filtration membrane, the above 1. It is possible to use the same solvent for the membrane-forming stock solution and the coagulating solution used in the production of the hollow-fiber membrane-shaped filtration membrane. However, as the coagulation liquid, only one type corresponding to the hollow fiber membrane-shaped external coagulation liquid is used.
次に、具体的な製造工程について説明する。
（１）製膜原液調製工程（ａ）：共重合体（Ｐ）１〜５質量％、およびポリ塩化ビニル１０〜２０質量％を溶媒に添加し、５０〜２００℃に加温して溶解させ製膜原液を得る。
（２）吐出工程（ｂ）：製膜原液をスリットより平膜状に吐出させる。
（３）製膜工程（ｃ）：吐出される平膜状の製膜原液を直ちに凝固液に浸漬させ冷却して平膜状の本発明の濾過膜を製膜させる。凝固液の温度は０〜５０℃である。
以上の製造工程を採ることにより、共重合体（Ｐ）がポリ塩化ビニル製多孔質膜に強固に保持された平膜状の本発明の濾過膜が形成される。
Next, a specific manufacturing process will be described.
(1) Film-forming stock solution preparation step (a): 1 to 5% by mass of the copolymer (P) and 10 to 20% by mass of polyvinyl chloride are added to a solvent and heated to 50 to 200° C. to be dissolved. Obtain a film forming stock solution.
(2) Discharging step (b): The stock solution for film formation is discharged from the slit in a flat film shape.
(3) Film-forming step (c): The flat film-forming stock solution to be discharged is immediately immersed in the coagulating liquid and cooled to form the flat film-shaped filter membrane of the present invention. The temperature of the coagulating liquid is 0 to 50°C.
By adopting the above production steps, the flat membrane-shaped filtration membrane of the present invention in which the copolymer (P) is firmly held by the polyvinyl chloride porous membrane is formed.
なお、製膜工程（ｃ）の後に、３０〜９５℃の温水または熱水を用いて溶媒等を除去する洗浄工程、溶媒を抽出によって除去する抽出工程、および４０〜７０℃の乾燥工程を行ってもよい。また、すぐに使用しないときはグリセリンやエタノールを含む保存液で保存すればよい。 In addition, after the film forming step (c), a washing step of removing the solvent and the like using hot water or hot water of 30 to 95° C., an extraction step of removing the solvent by extraction, and a drying step of 40 to 70° C. May be. When it is not used immediately, it may be stored in a storage solution containing glycerin or ethanol.
以下、本発明を実施例および比較例により更に詳細に説明するが、本発明はこれらに限定されない。
以下に本発明に係る共重合体（Ｐ）である共重合体（Ｐ１）〜（Ｐ４）、および本発明の範囲外の共重合体（Ｑ１）〜（Ｑ３）の合成例を示す。
Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto.
The synthesis examples of the copolymers (P1) to (P4), which are the copolymers (P) according to the present invention, and the copolymers (Q1) to (Q3) outside the scope of the present invention are shown below.
合成例１：共重合体（Ｐ１）
ＭＰＣ６．０ｇと、下記式（５）に示すＰＰＧＭＡ（ｎ＝１３）２４．０ｇとをジメチルアセトアミドと２−プロパノールの１：１混合溶媒１２０ｇに溶解し、４つ口フラスコに入れ、３０分間窒素を吹き込んだ。続いて、重合開始剤としてパーブチル−ＮＤ（登録商標）（日油（株）製）０．５５ｇを添加し、６０℃で３時間、さらに７０℃で２時間重合した。重合終了後、エバポレーションにより２−プロパノールを留去し濃度調整して５０質量％の共重合体（Ｐ１）を含むジメチルアセトアミド溶液を得た。
合成した共重合体（Ｐ１）の重量平均分子量測定方法を以下に示す。
6.0 g of MPC and 24.0 g of PPGMA (n=13) represented by the following formula (5) were dissolved in 120 g of a 1:1 mixed solvent of dimethylacetamide and 2-propanol and placed in a four-neck flask for 30 minutes under nitrogen. Blew in. Subsequently, 0.55 g of Perbutyl-ND (registered trademark) (manufactured by NOF CORPORATION) was added as a polymerization initiator, and polymerization was carried out at 60°C for 3 hours and further at 70°C for 2 hours. After completion of the polymerization, 2-propanol was distilled off by evaporation to adjust the concentration to obtain a dimethylacetamide solution containing 50% by mass of the copolymer (P1).
The method for measuring the weight average molecular weight of the synthesized copolymer (P1) is shown below.
＜分子量測定＞
得られた共重合体（Ｐ１）溶液を２ｗ／ｖ％になるよう溶離液である０．５質量％の臭化リチウムを含むメタノール／クロロホルム（４／６；容量比）で希釈した。この溶液を試験溶液とし、検出器に示唆屈折率計を用いてポリメチルメタクリレート標準による換算値としてＧＰＣによる重量平均分子量（Ｍｗ）を測定・算出した。
＜ＧＰＣ分析の測定条件＞
カラム；ＰＬ ｇｅｌ Ｍｉｘｅｄ Ｃの２本を直列に配列（PolymerLaboratories Ltd.製）、溶離溶媒；０．５重量％の臭化リチウムを含むクロロホルム／エタノール（６／４；容量比）溶液、標準物質；ポリメチルメタクリレート（Polymer Laboratories Ltd.製）、検出；示差屈折計ＲＩ−８０２０（東ソー株式会社製）、流速；０．５ｍＬ／分、試料溶液使用量；１００μＬ、カラム温度；４０℃。
<Molecular weight measurement>
The obtained copolymer (P1) solution was diluted with methanol/chloroform (4/6; volume ratio) containing 0.5% by mass of lithium bromide as an eluent so as to be 2 w/v%. This solution was used as a test solution, and a weight average molecular weight (Mw) by GPC was measured and calculated as a conversion value based on a polymethylmethacrylate standard using a suggestive refractometer as a detector.
<Measurement conditions for GPC analysis>
Column: Two PL gel Mixed Cs are arranged in series (manufactured by Polymer Laboratories Ltd.), elution solvent; chloroform/ethanol (6/4; volume ratio) solution containing 0.5 wt% lithium bromide, standard substance; Polymethylmethacrylate (manufactured by Polymer Laboratories Ltd.), detection; differential refractometer RI-8020 (manufactured by Tosoh Corporation), flow rate; 0.5 mL/min, sample solution usage amount; 100 μL, column temperature; 40° C.
合成例２〜７：共重合体（Ｐ２）〜（Ｐ４）、および共重合体（Ｑ１）〜（Ｑ３）
表１に示すモノマー組成で、表１に示すＭｗとなるように、重合液濃度、重合開始剤濃度や重合反応温度などを変更した以外は合成例１と同様にして各共重合体（Ｐ）及び共重合体（Ｑ）を合成した。Ｍｗは合成例１と同様に測定・算出した。結果を表１に示す。
Synthesis Examples 2 to 7: Copolymers (P2) to (P4), and Copolymers (Q1) to (Q3)
Each copolymer (P) was prepared in the same manner as in Synthesis Example 1 except that the polymerization solution concentration, the polymerization initiator concentration, the polymerization reaction temperature, etc. were changed so that the monomer composition shown in Table 1 would be the Mw shown in Table 1. And a copolymer (Q) were synthesized. Mw was measured and calculated in the same manner as in Synthesis Example 1. The results are shown in Table 1.
（実施例１）熱誘起相分離法による平膜状の本発明の濾過膜の製造
（１）製膜原液調製工程（ａ）：ポリ塩化ビニル（積水化学工業製）３０質量部を、ジメチルアセトアミド（ＤＭＡｃ）２０質量部に加えて１３０℃で６時間攪拌溶解した。次に、共重合体（Ｐ１）１０質量部を、ＤＭＡｃ１４０質量部に室温下で溶解した。調製したポリ塩化ビニル／ＤＭＡｃ溶液５０質量部と、共重合体（Ｐ１）／ＤＭＡｃ溶液１５０質量部とを６０℃で混合し製膜原液を得た。得られた製膜原液は均一透明溶液であった。製膜原液中の共重合体（Ｐ１）およびポリ塩化ビニルの濃度は表２に示した通りであった。
（２）吐出工程（ｂ）：１２０℃に保温した製膜原液をスリットより平膜状に吐出させた。
（３）製膜工程（ｃ）：吐出された平膜状の製膜原液を、純水の凝固液に浸漬させて製膜させ、巻き取った。この時、凝固液の温度は２０℃とした。
（４）洗浄工程：製膜が完了した平膜を９０℃の熱水で洗浄し、過剰の共重合体（Ｐ１）および溶媒を除去した。
（５）乾燥工程：洗浄後の平膜を４０℃で５時間乾燥させた。
以上の様にして、平膜状の本発明の濾過膜を製造した。以後、該濾過膜を実施例１の濾過膜１と称し、他の実施例についても同様に称する。得られた実施例１の濾過膜１を用いて以下の試験を行った。
(Example 1) Production of flat membrane-shaped filtration membrane of the present invention by thermally induced phase separation method (1) Membrane preparation liquid preparation step (a): 30 parts by mass of polyvinyl chloride (manufactured by Sekisui Chemical Co., Ltd.) and dimethylacetamide In addition to 20 parts by mass of (DMAc), the mixture was stirred and dissolved at 130° C. for 6 hours. Next, 10 parts by mass of the copolymer (P1) was dissolved in 140 parts by mass of DMAc at room temperature. 50 parts by mass of the prepared polyvinyl chloride/DMAc solution and 150 parts by mass of the copolymer (P1)/DMAc solution were mixed at 60° C. to obtain a stock solution for film formation. The obtained film forming stock solution was a uniform transparent solution. The concentrations of the copolymer (P1) and polyvinyl chloride in the stock solution for film formation were as shown in Table 2.
(2) Discharging step (b): The stock solution for film formation kept at 120° C. was discharged in a flat film form from the slit.
(3) Film forming step (c): The discharged flat film-forming stock solution was immersed in a coagulating solution of pure water to form a film, and the film was wound. At this time, the temperature of the coagulating liquid was 20°C.
(4) Washing step: The flat membrane on which the film formation was completed was washed with hot water at 90° C. to remove the excess copolymer (P1) and the solvent.
(5) Drying step: The flat membrane after washing was dried at 40° C. for 5 hours.
As described above, the flat membrane-shaped filtration membrane of the present invention was produced. Hereinafter, the filtration membrane is referred to as the filtration membrane 1 of Example 1, and the other examples are also referred to in the same manner. The following tests were conducted using the obtained filtration membrane 1 of Example 1.
実施例１の濾過膜１について、まず、純水を用いて透水量（ＬＭＨ／Ｂａｒ）を測定した（初期透水量）。続いて、モデルファウラントとして１，０００ｐｐｍの牛血清アルブミン溶液を用い、該溶液を６０分間透水した。その後、純水を用いて０．０１ＭＰａで透水方向を逆にした逆洗浄を２分間行った。逆洗浄後、再び純水を用いて透水量（ＬＭＨ／Ｂａｒ）を測定し（逆洗浄後透水量）、透水回復率（％）を評価した。透水回復率（％）とは下記式（６）で表される値である。透水量の単位「ＬＭＨ／Ｂａｒ」は、１気圧下、１時間当たり、濾過膜１ｍ２当たりの純水の濾過膜通過量（Ｌ）を表す。
結果を表２に示す。
透水回復率（％）＝（逆洗浄後透水量／初期透水量）×１００ （６）
Regarding the filtration membrane 1 of Example 1, first, the water permeation amount (LMH/Bar) was measured using pure water (initial water permeation amount). Subsequently, a 1,000 ppm bovine serum albumin solution was used as a model foulant, and the solution was permeated for 60 minutes. After that, back washing was performed with pure water at 0.01 MPa with the water permeability direction reversed, for 2 minutes. After backwashing, the water permeability (LMH/Bar) was measured again using pure water (water permeability after backwashing), and the water recovery rate (%) was evaluated. The water recovery rate (%) is a value represented by the following formula (6). The unit "LMH/Bar" of the amount of water permeation represents the amount (L) of pure water passing through the filtration membrane per 1 m 2 of the filtration membrane at 1 atmospheric pressure per hour.
The results are shown in Table 2.
Permeability recovery rate (%) = (water permeability after backwashing / initial water permeability) x 100 (6)
（実施例２〜５）
表１の合成例１〜４で合成された共重合体（Ｐ１）〜（Ｐ４）を使用し、各共重合体およびポリ塩化ビニルの濃度が表２に示す濃度となるように製膜原液を調製した以外は、実施例１と同様にして実施例２〜５の濾過膜２〜５を得た。濾過膜２〜５について、実施例１と同様に透水量および透水回復率を測定した。結果を表２に示す。
(Examples 2 to 5)
The copolymers (P1) to (P4) synthesized in Synthesis Examples 1 to 4 in Table 1 were used, and the film forming stock solution was prepared so that the concentration of each copolymer and polyvinyl chloride would be the concentrations shown in Table 2. Filter membranes 2-5 of Examples 2-5 were obtained like Example 1 except having prepared. For the filtration membranes 2 to 5, the water permeation amount and water permeation recovery rate were measured in the same manner as in Example 1. The results are shown in Table 2.
（比較例１、２）
表１の合成例１で合成された共重合体（Ｐ１）を使用し、各共重合体およびポリ塩化ビニルの濃度が表３に示す濃度となるように製膜原液を調製した以外は、実施例１と同様にして各比較例の濾過膜を得た。比較例１、２の濾過膜を各々濾過膜６、７とする。該濾過膜６、７について、実施例１と同様に透水量および透水回復率を測定した。結果を表３に示す。
(Comparative Examples 1 and 2)
Except that the copolymer (P1) synthesized in Synthesis Example 1 in Table 1 was used and the stock solution for film formation was prepared so that the concentration of each copolymer and polyvinyl chloride would be the concentrations shown in Table 3. In the same manner as in Example 1, a filtration membrane of each comparative example was obtained. The filtration membranes of Comparative Examples 1 and 2 are referred to as filtration membranes 6 and 7, respectively. For the filtration membranes 6 and 7, the water permeation amount and water permeation recovery rate were measured in the same manner as in Example 1. The results are shown in Table 3.
（比較例３〜５）
表１の合成例５〜７で合成された共重合体（Ｑ１）〜（Ｑ３）を使用し、各共重合体およびポリ塩化ビニルの濃度が表３に示す濃度となるように製膜原液を調製した以外は、実施例１と同様にして各比較例の濾過膜を得た。比較例３〜５の濾過膜を各々濾過膜８〜１０とする。該濾過膜８〜１０について、実施例１と同様に透水量および透水回復率を測定した。結果を表３に示す。
(Comparative Examples 3-5)
The copolymers (Q1) to (Q3) synthesized in Synthesis Examples 5 to 7 in Table 1 were used, and the film forming stock solutions were prepared so that the concentrations of the copolymers and polyvinyl chloride were the concentrations shown in Table 3. A filtration membrane of each comparative example was obtained in the same manner as in Example 1 except that it was prepared. The filtration membranes of Comparative Examples 3 to 5 are referred to as filtration membranes 8 to 10, respectively. With respect to the filtration membranes 8 to 10, the water permeation amount and the water permeation recovery rate were measured in the same manner as in Example 1. The results are shown in Table 3.
表２から明らかなように、実施例１〜５は、本発明の製造方法で製造した本発明の濾過膜を使用しているので、初期透水量、および透水回復率の点において、表３に示す比較例１、３、５に比較して顕著に優れていた。製膜原液が相分離した比較例２および４は濾過膜を製造できなかった。なお、比較例５は相分離したが濾過膜の製造は可能であった。
以上の通り、本発明に係る製造方法は、耐ファウリング性に顕著に優れる水処理用ポリ塩化ビニル製多孔質濾過膜を製造できることが判った。
As is clear from Table 2, since Examples 1 to 5 use the filtration membrane of the present invention produced by the production method of the present invention, Table 3 shows the results in terms of initial water permeability and water recovery rate. It was remarkably excellent as compared with Comparative Examples 1, 3, and 5 shown. Comparative Examples 2 and 4 in which the membrane-forming stock solution was phase-separated could not produce a filtration membrane. In addition, although Comparative Example 5 was phase-separated, it was possible to manufacture a filtration membrane.
As described above, it was found that the production method according to the present invention can produce a polyvinyl chloride porous filtration membrane for water treatment, which is remarkably excellent in fouling resistance.
Claims (1)
前記製膜原液をノズルまたはスリットを通して膜状に吐出させる吐出工程（ｂ）と、
吐出される前記膜状の製膜原液を凝固液に浸漬させ、多孔質膜を形成させる製膜工程（ｃ）と、を有し、
前記共重合体（Ｐ）は、下記式（１）のモノマー１０〜４０モル％と、下記式（２）のモノマー６０〜９０モル％との、重量平均分子量が１０，０００〜１，０００，０００の共重合体である、水処理用ポリ塩化ビニル製多孔質濾過膜の製造方法。
（式中、Ｒ１は水素原子又はメチル基を示し、Ｒ２およびＲ３はそれぞれ独立に炭素数１〜４のアルキレン基を示し、Ｒ４、Ｒ５およびＲ６はそれぞれ独立に炭素数１〜４のアルキル基を示す。）
（式中、Ｒ７は水素原子又はメチル基を示し、Ｒ８およびＲ９はそれぞれ独立に炭素数２〜４のアルキレン基を示し、Ｒ１０は水素原子又は炭素数１〜４のアルキル基を示す。ｎおよびｍはいずれも０〜１５であり、かつｎ＋ｍの値は７〜１５である。）
A film-forming stock solution preparing step (a) for preparing a film-forming stock solution containing 1 to 5 mass% of a copolymer (P) and 10 to 20 mass% of polyvinyl chloride;
A discharging step (b) of discharging the stock solution for film formation through a nozzle or a slit,
A film forming step (c) of forming a porous film by immersing the discharged film forming stock solution in a coagulating liquid.
The copolymer (P) has a weight average molecular weight of 10 to 40 mol% of the following formula (1) and 60 to 90 mol% of the following formula (2), and a weight average molecular weight of 10,000 to 1,000. 000 copolymer, which is a polyvinyl chloride porous filtration membrane for water treatment.
(In the formula, R 1 represents a hydrogen atom or a methyl group, R 2 and R 3 each independently represent an alkylene group having 1 to 4 carbon atoms, and R 4 , R 5, and R 6 each independently represent 1 carbon atom. ~ 4 alkyl groups are shown.)
(In the formula, R 7 represents a hydrogen atom or a methyl group, R 8 and R 9 each independently represent an alkylene group having 2 to 4 carbon atoms, and R 10 represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. (N and m are both 0 to 15 and the value of n+m is 7 to 15.)
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