JP2012187575A - Composite membrane and method for manufacturing the same - Google Patents
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本発明は、水処理分野、医薬品製造分野、食品工業分野などに好適に用いられる分離膜に関する。さらに詳しくは、液体中のウイルスなどの微小物を効率的に除去する分野に好適に使用できる複合膜及びその製造方法に関する。 The present invention relates to a separation membrane suitably used in the fields of water treatment, pharmaceutical production, food industry and the like. More specifically, the present invention relates to a composite membrane that can be suitably used in the field of efficiently removing minute substances such as viruses in a liquid and a method for producing the same.
近年、河川水や地下水の除濁、工業用水の清澄化、排水の高度処理などの浄水分野にフッ素系樹脂を用いた中空糸膜モジュールが適用されるようになってきた。これら浄水分野で用いられる中空糸膜モジュールには、長期運転を目的に酸、アルカリ、塩素、界面活性剤などの薬品洗浄を中空糸膜モジュールに施し、再生を繰り返して使用される。このために使用される中空糸膜には、高い耐薬品性能（化学的強度）、物理強度が要求され、加えてクリプトスポリジウムなどの病原性微生物が透過処理水に混入しない分離特性が必要とされている。また飲料水製造、医薬品製造、食品工業分野では、製造工程内にウイルスなどの病原体が混入した場合、製造ラインが汚染され、ウイルス感染症などを引き起こす危険性がある。このために種々の殺菌技術が用いられ、ウイルスを細孔で物理的に除去できる分離膜の利用が注目されるようになってきた。このように分離膜には、優れた分離性能、化学的強度（耐薬品性）、物理強度、及び透過性能が求められている。この様な特性要求に対して化学的強度（耐薬品性）を有するポリフッ化ビニリデン系樹脂の分離膜が用いられるようになって来た。しかしながらポリフッ化ビニリデン樹脂製の分離膜は、化学的強度（耐薬品性）が高いものの、膜面に疎水性相互作用があって汚れ易く、透水性能が低下する。 In recent years, hollow fiber membrane modules using fluororesins have been applied to water purification fields such as river water and groundwater clarification, clarification of industrial water, and advanced treatment of wastewater. For these hollow fiber membrane modules used in the water purification field, chemical cleaning such as acid, alkali, chlorine and surfactant is applied to the hollow fiber membrane module for the purpose of long-term operation, and regeneration is used repeatedly. The hollow fiber membranes used for this purpose require high chemical resistance (chemical strength) and physical strength, and in addition, separation characteristics that prevent pathogenic microorganisms such as Cryptosporidium from entering the permeated water are required. ing. Also, in the fields of drinking water production, pharmaceutical production, and food industry, when a pathogen such as a virus is mixed in the production process, the production line is contaminated and there is a risk of causing a virus infection. For this purpose, various sterilization techniques have been used, and the use of separation membranes that can physically remove viruses through pores has attracted attention. Thus, the separation membrane is required to have excellent separation performance, chemical strength (chemical resistance), physical strength, and permeation performance. Polyvinylidene fluoride resin separation membranes having chemical strength (chemical resistance) have been used in response to such characteristic requirements. However, although the separation membrane made of polyvinylidene fluoride resin has high chemical strength (chemical resistance), it has a hydrophobic interaction on the membrane surface and is easily soiled, resulting in a decrease in water permeability.
このためにポリフッ化ビニリデン樹脂の疎水性相互作用を低下させる、親水化による耐汚れ性、透水性、或いはウイルス除去性の改善が行われてきた。例えば特許文献１に記載の方法では、酢酸セルロースとポリフッ化ビニリデン系樹脂をブレンドした分離膜の製造方法が開示されている。しかし、単層系の膜で親水性の効果が発現するまで酢酸セルロースをブレンドした場合、酸、アルカリ、塩素などの耐薬品性が低く、機械的強度が低下する懸念がある。また特許文献２には、表層に親水性高分子を含有するフッ素系樹脂を形成させて、高い物理強度や透水性能などを有する複合膜が開示されている。しかし、この複合膜は膜細孔が粗いためにウイルスなどの微小物を除去する分離特性が低い。また特許文献３では、表層に親水性高分子を含有するフッ素系樹脂で形成させた複合膜が高い分離特性を有することが開示されている。しかしながらウイルス除去性は低く、不十分であった。また特許文献４には、医療用途の中空糸膜の記載がある。しかし、高いウイルス除去性能を示すものの膜厚が薄いために物理的強度が低く、さらに透過性能も低い。また特許文献５では、表層に親水性高分子を含有するフッ素系樹脂で形成させた複合膜が高いウイルス除去性（初期）を有することが開示されている。しかしながらウイルス除去性については、未だ不十分であった。 For this reason, the stain resistance, water permeability, or virus removal property has been improved by reducing the hydrophobic interaction of the polyvinylidene fluoride resin. For example, the method described in Patent Document 1 discloses a method for producing a separation membrane in which cellulose acetate and a polyvinylidene fluoride resin are blended. However, when cellulose acetate is blended until a hydrophilic effect is exhibited in a single-layer film, chemical resistance such as acid, alkali, and chlorine is low, and there is a concern that mechanical strength is lowered. Patent Document 2 discloses a composite film having a high physical strength, water permeability, and the like by forming a fluororesin containing a hydrophilic polymer on the surface layer. However, since this composite membrane has rough membrane pores, it has low separation characteristics for removing microscopic substances such as viruses. Patent Document 3 discloses that a composite membrane formed of a fluororesin containing a hydrophilic polymer in the surface layer has high separation characteristics. However, virus removability was low and insufficient. Patent Document 4 describes a hollow fiber membrane for medical use. However, although it exhibits high virus removal performance, its physical strength is low due to the thin film thickness, and the permeation performance is also low. Patent Document 5 discloses that a composite film formed of a fluororesin containing a hydrophilic polymer on the surface layer has high virus removability (initial). However, the virus removability was still insufficient.
本発明は上記のような問題点に鑑み、優れたウイルス除去性能、及び耐汚れ性を有するポリフッ化ビニリデン系樹脂を分離層に用いた複合膜及びその製造方法を提供することを目的とする。 In view of the above problems, an object of the present invention is to provide a composite membrane using a polyvinylidene fluoride resin having excellent virus removal performance and stain resistance as a separation layer, and a method for producing the same.
上記の課題を達成するために以下の構成からなる。 In order to achieve the above-mentioned problem, the following configuration is provided.
（１）支持膜と、セルロースエステルを９重量％以上４６重量％以下、かつ溶融粘度が３３００Ｐａ・ｓ以上を含有するポリフッ化ビニリデン系樹脂で前記支持膜上に形成されるコート層とを備え、
該コート層の最外表面孔径が平均０．０１μｍ以上０．１μｍ以下であり、コート層内に平均孔径０．０１μｍ以上０．５μｍ以下、かつ厚さ１０μｍ以上１２０μｍ以下の三次元網目構造が形成されていることを特徴とする複合膜。
(1) A support film and a coating layer formed on the support film with a polyvinylidene fluoride-based resin containing 9 to 46% by weight of cellulose ester and a melt viscosity of 3300 Pa · s or more,
The outermost surface pore diameter of the coat layer is 0.01 μm or more and 0.1 μm or less on average, and a three-dimensional network structure having an average pore diameter of 0.01 μm or more and 0.5 μm or less and a thickness of 10 μm or more and 120 μm or less is formed in the coat layer. A composite membrane characterized by being made.
（２）溶融粘度３３００Ｐａ・ｓ以上のポリフッ化ビニリデン系樹脂を１４重量％以上２０重量％以下、かつセルロースエステルを２重量％以上１２重量％以下の範囲で含有するコート溶液を、支持膜表面にコーティングした後、凝固させることで、該支持膜に分離機能層を形成することを特徴とする複合膜の製造方法。 (2) A coating solution containing a polyvinylidene fluoride resin having a melt viscosity of 3300 Pa · s or more in a range of 14 wt% or more and 20 wt% or less and a cellulose ester in a range of 2 wt% or more and 12 wt% or less on the surface of the support membrane. A method for producing a composite membrane comprising forming a separation functional layer on the support membrane by solidifying after coating.
本発明の製造方法により、簡素なプロセスで支持膜に優れたウイルス除去性能、及び耐汚れ性を有するポリフッ化ビニリデン樹脂を用いた分離機能層を複合膜化した複合膜及びその製造方法を提供することができる。 By the production method of the present invention, there is provided a composite membrane in which a separation functional layer using a polyvinylidene fluoride resin having a virus removal performance and stain resistance excellent in a support membrane by a simple process is made into a composite membrane, and a method for producing the composite membrane. be able to.
以下、本発明のポリフッ化ビニリデン系樹脂を用いた複合膜の製造方法の具体的な実施形態について述べる。 Hereinafter, specific embodiments of a method for producing a composite film using the polyvinylidene fluoride resin of the present invention will be described.
本発明の複合膜に使用される支持膜（支持体）の形態としては、中空糸膜、管状膜、組み紐状などで支持体として透水性を有するもので、ポリマー溶液をコーティング可能なものであれば特に限定するものではない。中でも中空糸膜が連続コーティングなどの生産性において好ましく用いられる。 The support membrane (support) used in the composite membrane of the present invention may be a hollow fiber membrane, tubular membrane, braided or the like having water permeability as a support and capable of coating a polymer solution. There is no particular limitation. Among these, hollow fiber membranes are preferably used in productivity such as continuous coating.
本発明に使用される支持膜用の樹脂としては、鎖状高分子からなる熱可塑性樹脂が好ましく用いられる。例えばポリエチレン、ポリプロピレン、アクリル樹脂、ポリアクリロニトリル、アクリロニトリル−ブタジエン−スチレン（ＡＢＳ）樹脂、ポリスチレン、アクリロニトリル−スチレン（ＡＳ）樹脂、塩化ビニル樹脂、ポリエチレンテレフタレート、ポリアミド、ポリアセタール、ポリカーボネート、変性ポリフェニレンエーテル、ポリフェニレンスルフィド、ポリフッ化ビニリデン、ポリアミドイミド、ポリテーテルイミド、ポリスルホン、ポリエーテルスルホン及びこれらの混合物や共重合体が挙げられる。中でも耐薬品性に優れたポリフッ化ビニリデン系樹脂が好ましく用いられる。 As the resin for the support membrane used in the present invention, a thermoplastic resin composed of a chain polymer is preferably used. For example, polyethylene, polypropylene, acrylic resin, polyacrylonitrile, acrylonitrile-butadiene-styrene (ABS) resin, polystyrene, acrylonitrile-styrene (AS) resin, vinyl chloride resin, polyethylene terephthalate, polyamide, polyacetal, polycarbonate, modified polyphenylene ether, polyphenylene sulfide , Polyvinylidene fluoride, polyamideimide, polytheterimide, polysulfone, polyethersulfone, and mixtures and copolymers thereof. Of these, a polyvinylidene fluoride resin excellent in chemical resistance is preferably used.
ポリフッ化ビニリデン系樹脂とは、フッ化ビニリデンホモポリマーおよび／またはフッ化ビニリデン共重合体を含有する樹脂で、複数のフッ化ビニリデン共重合体を含有しても構わない。フッ化ビニリデン共重合体は、フッ化ビニリデンの残基構造を有するポリマーであり、典型的にはフッ化ビニリデンモノマーとそれ以外のフッ素系モノマーなどとの共重合体である。かかる共重合体としては、例えば、フッ化ビニル、四フッ化エチレン、六フッ化プロピレン、三フッ化塩化エチレンから選ばれた１種類以上とフッ化ビニリデンとの共重合体が挙げられる。また、本発明の効果を損なわない程度に、前記フッ素系モノマー以外の例えばエチレンなどのモノマーが共重合されていても良い。中でも化学的強度の高さからフッ化ビニリデンホモポリマーからなる樹脂が好ましく用いられる。上述したポリフッ化ビニリデン系樹脂を支持膜に用いる場合、物理的強度や透水性を考慮すると重量平均分子量が１０万以上７０万以下の範囲内にあることが好ましく、溶媒への溶解性を考慮すると重量平均分子量２０万以上６０万以下のものが好ましく用いられる。 The polyvinylidene fluoride resin is a resin containing a vinylidene fluoride homopolymer and / or a vinylidene fluoride copolymer, and may contain a plurality of vinylidene fluoride copolymers. The vinylidene fluoride copolymer is a polymer having a vinylidene fluoride residue structure, and is typically a copolymer of a vinylidene fluoride monomer and other fluorine-based monomers. Examples of the copolymer include a copolymer of vinylidene fluoride and at least one selected from vinyl fluoride, tetrafluoroethylene, hexafluoropropylene, and trifluoroethylene chloride. Further, a monomer such as ethylene other than the fluorine-based monomer may be copolymerized to such an extent that the effects of the present invention are not impaired. Among them, a resin made of vinylidene fluoride homopolymer is preferably used because of its high chemical strength. When the above-mentioned polyvinylidene fluoride resin is used for the support membrane, it is preferable that the weight average molecular weight is in the range of 100,000 or more and 700,000 or less in consideration of physical strength and water permeability, and considering the solubility in a solvent. Those having a weight average molecular weight of 200,000 or more and 600,000 or less are preferably used.
本発明に係る支持膜の製造方法としては、冷却による熱誘起相分離法や非溶媒誘起相分離法など公知の製造方法などが採用できる。例えばポリフッ化ビニリデン系樹脂溶液の冷却による熱誘起相分離法の場合、ここでは重量平均分子量１０万以上７０万以下のポリフッ化ビニリデン系樹脂を２０重量％以上６０重量％以下の濃度で、ポリフッ化ビニリデン系樹脂の貧溶媒もしくは良溶媒に結晶化温度以上の温度で溶解する。ポリフッ化ビニリデン系樹脂濃度を高くすれば、物理強度の高い支持膜が得られるが、分離膜の空孔率が小さくなり透過性能が低下傾向を示すので考慮する必要がある。従ってポリフッ化ビニリデン系樹脂濃度は３０重量％以上５０重量％以下の範囲とすることが好ましい。該ポリフッ化ビニリデン系樹脂溶液をＴダイ、二重管式口金などで、シート状或いは中空糸状に賦形して、冷却固化する。冷却浴には０℃以上３０℃以下で、濃度が５０重量％以上９５重量％以下の貧溶媒あるいは良溶媒と、濃度が５重量％以上５０重量％以下の非溶媒からなる混合液体が好ましい。また、中空糸状に成形する際には、該ポリフッ化ビニリデン系樹脂溶液と同時に二重管式口金の中心パイプから中空部形成液体を吐出させる方法が好ましい。中空部形成液体には、冷却浴同様、濃度が７５重量％以上９５重量％以下の貧溶媒あるいは良溶媒と、濃度が５重量％以上２５重量％以下の非溶媒からなる混合液体が好ましい。さらに貧溶媒としては樹脂溶液と同じ貧溶媒を用いることが好ましく採用される。 As a method for producing a support membrane according to the present invention, a known production method such as a heat-induced phase separation method by cooling or a non-solvent-induced phase separation method can be employed. For example, in the case of a thermally induced phase separation method by cooling a polyvinylidene fluoride resin solution, here, a polyvinylidene fluoride resin having a weight average molecular weight of 100,000 to 700,000 at a concentration of 20 wt% to 60 wt% It dissolves in a poor solvent or good solvent of vinylidene resin at a temperature higher than the crystallization temperature. If the concentration of the polyvinylidene fluoride resin is increased, a support membrane having high physical strength can be obtained. However, since the porosity of the separation membrane decreases and the permeation performance tends to decrease, it is necessary to consider. Accordingly, the concentration of the polyvinylidene fluoride resin is preferably in the range of 30 wt% to 50 wt%. The polyvinylidene fluoride resin solution is shaped into a sheet shape or a hollow fiber shape with a T die, a double tube die, or the like, and then cooled and solidified. The cooling bath is preferably a mixed liquid composed of a poor solvent or a good solvent having a concentration of 50% to 95% by weight and a non-solvent having a concentration of 5% to 50% by weight at 0 ° C. to 30 ° C. Further, when forming into a hollow fiber shape, it is preferable to discharge the hollow portion forming liquid from the central pipe of the double tube type die simultaneously with the polyvinylidene fluoride resin solution. The hollow portion forming liquid is preferably a mixed liquid comprising a poor solvent or a good solvent having a concentration of 75% by weight to 95% by weight and a non-solvent having a concentration of 5% by weight to 25% by weight, as in the cooling bath. Further, it is preferable to use the same poor solvent as the resin solution as the poor solvent.
以上の支持膜の製造方法に加えて、透過性能を向上させるために延伸を行うことも好ましい。延伸温度は、好ましくは５０℃以上１６５℃以下が好ましい。５０℃以上であると延伸配向が均一に起こりやすくなり、１６５℃以下であるとポリフッ化ビニリデンの融点近くになるので、膜表面の微細孔の部分消失などを抑制することができる。延伸倍率は１．１倍以上４倍以下が好ましく、より好ましくは１．１倍以上２倍以下である。１．１倍以上であると透過性能が向上し、４倍以下であると糸の伸度低下を抑制することができる。 In addition to the above method for producing a support membrane, it is also preferable to perform stretching in order to improve the permeation performance. The stretching temperature is preferably 50 ° C. or higher and 165 ° C. or lower. When the temperature is 50 ° C. or higher, stretch orientation is likely to occur uniformly, and when the temperature is 165 ° C. or lower, the melting point of polyvinylidene fluoride is close to the melting point. The draw ratio is preferably 1.1 to 4 times, more preferably 1.1 to 2 times. If it is 1.1 times or more, the permeation performance is improved, and if it is 4 times or less, a decrease in the elongation of the yarn can be suppressed.
本発明における貧溶媒とは、ポリフッ化ビニリデン系樹脂を６０℃未満の低温では５重量％以上溶解させることができないが、６０℃以上かつポリフッ化ビニリデン系樹脂の融点以下（例えばポリフッ化ビニリデン系樹脂がポリフッ化ビニリデンホモポリマー単独で構成される場合は１７８℃程度）の高温領域で５重量％以上溶解させることができる溶媒のことである。ここで、本発明における貧溶媒を例示すると、シクロヘキサノン、イソホロン、γ−ブチロラクトン、メチルイソアミルケトン、プロピレンカーボネート、等の中鎖長のアルキルケトン、エステル、および有機カーボネートおよびその混合溶媒などが挙げられる。 The poor solvent in the present invention is that the polyvinylidene fluoride resin cannot be dissolved by 5% by weight or more at a low temperature of less than 60 ° C., but it is 60 ° C. or more and below the melting point of the polyvinylidene fluoride resin (for example, polyvinylidene fluoride resin Is a solvent that can be dissolved by 5 wt% or more in a high temperature region of about 178 ° C. when the polyvinylidene fluoride homopolymer is used alone. Examples of the poor solvent in the present invention include cyclohexanone, isophorone, γ-butyrolactone, methyl isoamyl ketone, propylene carbonate, and other medium chain length alkyl ketones, esters, organic carbonates, and mixed solvents thereof.
良溶媒としては、ポリフッ化ビニリデン系樹脂及びセルロースエステルを溶解し、好ましくは非溶媒誘起相分離により三次元網目構造を形成するものであればとくに制限されないが、ジメチルスルホキシド、Ｎ，Ｎ−ジメチルホルムアミド、Ｎ，Ｎ−ジメチルアセトアミド、Ｎ−メチル−２−ピロリドン、メチルエチルケトン、アセトン、テトラヒドロフラン、テトラメチル尿素、リン酸トリメチル等の低級アルキルケトン、エステル、アミドおよびそれらの混合溶媒などが挙げられる。ここで良溶媒とは、６０℃未満の低温でもポリフッ化ビニリデン系樹脂を５重量％以上溶解させることが可能な溶媒である。 The good solvent is not particularly limited as long as it dissolves polyvinylidene fluoride resin and cellulose ester, and preferably forms a three-dimensional network structure by non-solvent induced phase separation, but dimethyl sulfoxide, N, N-dimethylformamide , N, N-dimethylacetamide, N-methyl-2-pyrrolidone, methyl ethyl ketone, acetone, tetrahydrofuran, tetramethylurea, lower alkyl ketones such as trimethyl phosphate, esters, amides, and mixed solvents thereof. Here, the good solvent is a solvent capable of dissolving 5% by weight or more of the polyvinylidene fluoride resin even at a low temperature of less than 60 ° C.
また非溶媒は、ポリフッ化ビニリデン系樹脂の融点または溶媒の沸点まで、ポリフッ化ビニリデン系樹脂を溶解も膨潤もさせない溶媒と定義する。ここでポリフッ化ビニリデン系樹脂の非溶媒としては、水、ヘキサン、ペンタン、ベンゼン、トルエン、メタノール、エタノール、四塩化炭素、ｏ−ジクロルベンゼン、トリクロルエチレン、エチレングリコール、ジエチレングリコール、トリエチレングリコール、プロピレングリコール、ブチレングリコール、ペンタンジオール、ヘキサンジオール、低分子量のポリエチレングリコール等の脂肪族炭化水素、芳香族炭化水素、脂肪族多価アルコール、芳香族多価アルコール、塩素化炭化水素、またはその他の塩素化有機液体およびその混合溶媒などが挙げられる。 The non-solvent is defined as a solvent that does not dissolve or swell the polyvinylidene fluoride resin up to the melting point of the polyvinylidene fluoride resin or the boiling point of the solvent. Here, as the non-solvent of the polyvinylidene fluoride resin, water, hexane, pentane, benzene, toluene, methanol, ethanol, carbon tetrachloride, o-dichlorobenzene, trichloroethylene, ethylene glycol, diethylene glycol, triethylene glycol, propylene Aliphatic hydrocarbons such as glycol, butylene glycol, pentanediol, hexanediol, low molecular weight polyethylene glycol, aromatic hydrocarbons, aliphatic polyhydric alcohols, aromatic polyhydric alcohols, chlorinated hydrocarbons, or other chlorinations Examples thereof include organic liquids and mixed solvents thereof.
本発明の分離機能層に用いるポリフッ化ビニリデン系樹脂の場合、溶融粘度３３００Ｐａ・ｓ以上のポリフッ化ビニリデン系樹脂が用いられるが、一般的に溶融粘度と重量平均分子量との関係が一義的に決まることから、溶融粘度３３００Ｐａ・ｓ以上に相当する重量平均分子量のポリフッ化ビニリデン系樹脂を用いても良い。溶融粘度３３００Ｐａ・ｓ以上となるポリフッ化ビニリデン系樹脂の重量平均分子量としては、一般的に８０万以上であるが、９０万以上であればより確実に達成される。溶融粘度が３３００Ｐａ・ｓ以上、あるいは重量平均分子量が８０万以上であるとポリマー密度が高くなりウイルス除去などの分離特性を向上させることができる。ここで、ポリフッ化ビニリデン系樹脂の溶融粘度の上限については特に制限はないが、７０００Ｐａ・ｓを超える、あるいは重量平均分子量が１６０万を超えると、溶媒への溶解性の低下、或いは複合膜にした場合の透水性が低下する懸念がある。 In the case of the polyvinylidene fluoride resin used in the separation functional layer of the present invention, a polyvinylidene fluoride resin having a melt viscosity of 3300 Pa · s or more is used, but generally the relationship between the melt viscosity and the weight average molecular weight is uniquely determined. Therefore, a polyvinylidene fluoride resin having a weight average molecular weight corresponding to a melt viscosity of 3300 Pa · s or more may be used. The weight average molecular weight of the polyvinylidene fluoride resin having a melt viscosity of 3300 Pa · s or more is generally 800,000 or more, but more reliably achieved if it is 900,000 or more. When the melt viscosity is 3300 Pa · s or more, or the weight average molecular weight is 800,000 or more, the polymer density becomes high and separation characteristics such as virus removal can be improved. Here, the upper limit of the melt viscosity of the polyvinylidene fluoride resin is not particularly limited, but if it exceeds 7000 Pa · s or the weight average molecular weight exceeds 1,600,000, the solubility in a solvent decreases, or the composite film There is a concern that the water permeability will decrease.
本発明に用いられるコート溶液は、溶融粘度３３００Ｐａ・ｓ以上のポリフッ化ビニリデン系樹脂を１４重量％以上２０重量％以下、かつセルロースエステルを２重量％以上１２重量％以下含有する樹脂溶液である。通常、単一組成のポリフッ化ビニリデン系樹脂溶液をコート溶液に用いて非溶媒誘起相分離法で凝固させる場合、溶融粘度の低いポリフッ化ビニリデン系樹脂溶液を用いると凝集性が低いために三次元網目構造が粗くなり、マクロボイドのような大きな空隙を形成する、一方で溶融粘度の高いポリフッ化ビニリデン系樹脂溶液を用いると凝集性が高くなり高分子リッチ相のネットワーク（三次元網目構造）の孔が細かく形成する。なお、本発明においてマクロボイドとは、非溶媒誘起相分離で形成されたコート層（分離機能層）において平均孔径が５μｍを超える孔のことを指す。 The coating solution used in the present invention is a resin solution containing 14% by weight to 20% by weight of a polyvinylidene fluoride resin having a melt viscosity of 3300 Pa · s or more and 2% by weight to 12% by weight of a cellulose ester. Normally, when a single composition polyvinylidene fluoride resin solution is used as a coating solution and solidified by a non-solvent induced phase separation method, the use of a polyvinylidene fluoride resin solution having a low melt viscosity results in a low cohesiveness, resulting in a three-dimensional structure. The network structure becomes coarse and large voids such as macrovoids are formed. On the other hand, when a polyvinylidene fluoride resin solution having a high melt viscosity is used, the cohesiveness increases and the polymer rich phase network (three-dimensional network structure) Holes are finely formed. In addition, in this invention, a macrovoid refers to a hole with an average hole diameter exceeding 5 micrometers in the coating layer (separation functional layer) formed by the non-solvent induced phase separation.
本発明の分離機能層の構造制御するために、ポリフッ化ビニリデン系樹脂中に相溶性の高いセルロースエステルを加えることで、ポリフッ化ビニリデン系樹脂の凝集性を調整し、コーティングしたコート層壁内に高い分離機能を果たす三次元網目構造を形成することが可能になる。 In order to control the structure of the separation functional layer of the present invention, the cohesiveness of the polyvinylidene fluoride resin is adjusted by adding a highly compatible cellulose ester in the polyvinylidene fluoride resin, and the coating layer wall is coated. It becomes possible to form a three-dimensional network structure that performs a high separation function.
本発明では、ポリフッ化ビニリデン系樹脂の溶融粘度が３３００Ｐａ・ｓ以上であることが必要であり、好ましくは３５００Ｐａ・ｓ以上である。溶融粘度が３３００Ｐａ・ｓ以上であることで分離機能層に形成する三次元網目の細孔を小さくすることできるために、ウイルス除去性などの分離特性を向上させることができ、本発明が達成される。また上限については特に制限はないが、７０００Ｐａ・ｓを超えると、樹脂の溶解性低下などの製造上の懸念がある。ここで、ポリフッ化ビニリデン系樹脂の溶融粘度は、ＡＳＴＭ Ｄ３８３５／２３２℃に剪断速度１００秒−１の条件下で測定することができる。 In the present invention, it is necessary that the melt viscosity of the polyvinylidene fluoride resin is 3300 Pa · s or more, preferably 3500 Pa · s or more. When the melt viscosity is 3300 Pa · s or more, the pores of the three-dimensional network formed in the separation functional layer can be reduced, so that separation characteristics such as virus removability can be improved, and the present invention is achieved. The The upper limit is not particularly limited, but if it exceeds 7000 Pa · s, there is a manufacturing concern such as a decrease in the solubility of the resin. Here, the melt viscosity of the polyvinylidene fluoride resin can be measured under the conditions of ASTM D3835 / 232 ° C. and a shear rate of 100 seconds− 1 .
またコート溶液におけるポリフッ化ビニリデン系樹脂の濃度が、１４重量％以上２０重量％以下であることが必要であり、好ましくは１４重量％以上１８重量％以下である。ポリフッ化ビニリデン系樹脂の濃度が１４重量％以上であると、ウイルス除去性などの分離特性が向上する。一方で２０重量％以下であると透水性が向上するため、本発明が達成される。 Further, the concentration of the polyvinylidene fluoride resin in the coating solution needs to be 14% by weight or more and 20% by weight or less, and preferably 14% by weight or more and 18% by weight or less. When the concentration of the polyvinylidene fluoride resin is 14% by weight or more, separation characteristics such as virus removability are improved. On the other hand, if it is 20% by weight or less, the water permeability is improved, so that the present invention is achieved.
また本発明でコート溶液中のセルロースエステルの濃度は、２重量％以上１２重量％以下であることが必要であり、好ましくは３重量％以上１２重量％以下、さらに好ましくは５重量％以上１０重量％以下である。セルロースエステルを２重量％以上にすると、ポリフッ化ビニリデン系樹脂との相溶性が向上することで三次元網目構造の細孔を均質的に形成することが可能になり、分離特性、及び耐ファウリング性などが向上する。一方で１２重量％以下にすると溶解性が向上し、薬品による物性値の低下を軽減することができるため、本発明が達成される。ここでセルロースエステルとは、繰り返し単位中に３つのエステル基を有し、それらの加水分解の程度を調整したセルロースアセテート、セルロースアセテートプロピオネート、セルロースアセテートブチレートから少なくとも１種以上選ばれるものである。 In the present invention, the concentration of the cellulose ester in the coating solution needs to be 2 wt% or more and 12 wt% or less, preferably 3 wt% or more and 12 wt% or less, more preferably 5 wt% or more and 10 wt% or less. % Or less. When the cellulose ester content is 2% by weight or more, the compatibility with the polyvinylidene fluoride resin is improved, so that pores with a three-dimensional network structure can be formed uniformly, and the separation characteristics and fouling resistance are improved. Improve. On the other hand, when the content is 12% by weight or less, the solubility is improved, and the decrease in the physical property value due to the chemical can be reduced, so that the present invention is achieved. Here, the cellulose ester is one selected from cellulose acetate, cellulose acetate propionate, and cellulose acetate butyrate having three ester groups in the repeating unit and adjusting the degree of hydrolysis thereof. is there.
本発明の複合膜の製造方法では、コート溶液を支持膜表面にコーティングした後、凝固液に接触させて凝固させる。凝固液の接触方法は、凝固液をスプレーノズルなどで霧化して吹きつけ、或いは浴中で直接接触させることで良い。中空糸状に賦形する場合、溶液粘度に合わせて、例えば特開２００４−３１４０５９号公報に記載の弾性体で構成されるコートノズル、或いは金属、セラミックスなどで構成される円形ノズルを用いてコーティングすることが可能である。またシート状に賦形する場合、例えばＴダイから引き出した支持膜にスリットコータでコーティングすることが可能である。またコート溶液と支持膜溶液を３重管状ノズルなどから中空部形成流体と同時に賦形しながら中空糸状に吐出して、非溶媒誘起相分離法などで製膜紡糸しても何ら構わない。 In the method for producing a composite membrane of the present invention, the coating solution is coated on the surface of the support membrane, and then solidified by contacting with a coagulation liquid. The coagulating liquid may be contacted by atomizing and spraying the coagulating liquid with a spray nozzle or the like, or directly contacting in the bath. In the case of forming into a hollow fiber shape, coating is performed using a coating nozzle made of an elastic body described in, for example, Japanese Patent Application Laid-Open No. 2004-314059, or a circular nozzle made of metal, ceramics, or the like according to the solution viscosity. It is possible. Further, when forming into a sheet shape, for example, it is possible to coat the support film drawn from the T-die with a slit coater. Also, the coating solution and the supporting membrane solution may be discharged into a hollow fiber shape while forming simultaneously with the hollow portion forming fluid from a triple tubular nozzle or the like, and the membrane spinning may be performed by a non-solvent induced phase separation method or the like.
コート溶液の溶液粘度は、１００Ｐａ・ｓ以上３００Ｐａ・ｓ以下であることが好ましい。コート溶液の溶液粘度が１００Ｐａ・ｓ以上であるとコート溶液中の溶媒拡散が遅くなり、三次元網目構造の孔が細かく形成し易くなる。また３００Ｐａ・ｓ以下であると緻密化による透水性低下を抑制すると共に、コーティング時のズリ応力による糸変形を軽減して、本発明が達成される。なおコーティングに際して、コート溶液の濡れ性不足や剪断応力など支持膜に負荷がかからない程度に、支持膜及びコート溶液を６０℃以上１２０℃以下に加熱することであっても良い。 The solution viscosity of the coating solution is preferably 100 Pa · s or more and 300 Pa · s or less. When the solution viscosity of the coating solution is 100 Pa · s or more, the solvent diffusion in the coating solution is slowed, and the pores of the three-dimensional network structure are easily formed. Further, when the pressure is 300 Pa · s or less, the water permeability is reduced by densification, and the yarn deformation due to shear stress during coating is reduced, thereby achieving the present invention. In coating, the support film and the coating solution may be heated to 60 ° C. or more and 120 ° C. or less to such an extent that a load is not applied to the support film such as insufficient wettability of the coating solution or shear stress.
ここで、コート溶液の溶液粘度は、溶液を６０℃に保温して回転式デジタル粘度計（型式：ＰＶ-II＋Ｐｒｏ，米国ブルックフィールド社製）で測定することができる。 Here, the solution viscosity of the coating solution can be measured with a rotary digital viscometer (model: PV-II + Pro, manufactured by Brookfield, USA) while keeping the solution at 60 ° C.
本発明で用いる凝固液としては、透水性と分離特性など考慮して、上述した良溶媒・貧溶媒と非溶媒との混合液が好ましく用いられる。凝固液の非溶媒濃度は、８０％以上であることが好ましく、８５％以上であると三次元網目構造の孔を小さく均質的に発現することができるのでさらに好ましく用いられる。凝固浴温度は、非溶媒相分離における拡散速度を制御するために２０℃以上８０℃以下であることが好ましく、さらに好ましくは３０℃以上６０℃以下である。凝固浴温度が２０℃以上であると透水性が向上し、８０℃以下であると表面細孔径を小さくできるので分離特性を向上させるため、本発明が達成される。 As the coagulating liquid used in the present invention, in consideration of water permeability and separation characteristics, a mixed liquid of the above-mentioned good solvent / poor solvent and non-solvent is preferably used. The non-solvent concentration of the coagulation liquid is preferably 80% or more, and more preferably 85% or more, since the pores of the three-dimensional network structure can be expressed small and homogeneously. The coagulation bath temperature is preferably 20 ° C. or higher and 80 ° C. or lower, more preferably 30 ° C. or higher and 60 ° C. or lower in order to control the diffusion rate in the non-solvent phase separation. When the coagulation bath temperature is 20 ° C. or higher, the water permeability is improved, and when it is 80 ° C. or lower, the surface pore diameter can be reduced, so that the separation characteristics are improved.
本発明に係るポリフッ化ビニリデン系樹脂の複合膜について、以下に説明する。 The composite film of polyvinylidene fluoride resin according to the present invention will be described below.
図１は本発明に係る中空糸状複合膜を構成する膜壁断面構造を示す図面代用写真（１０００倍）であり、図２は本発明に係る中空糸状複合膜を構成する膜壁最外表面を示す図面代用写真（３００００倍）である。 FIG. 1 is a drawing-substituting photograph (1000 times) showing the cross-sectional structure of the membrane wall constituting the hollow fiber composite membrane according to the present invention, and FIG. 2 shows the outermost surface of the membrane wall constituting the hollow fiber composite membrane according to the present invention. It is the drawing substitute photograph shown (30000 times).
これらの複合膜の構造は、溶融粘度３３００Ｐａ・ｓ以上のポリフッ化ビニリデン系樹脂を５４重量％以上９１重量％以下、かつセルロースエステルを９重量％以上４６重量％以下含有する三次元網目構造の分離機能層（コート層）と、それに続く球状構造の支持膜とで形成される。ポリフッ化ビニリデン系樹脂が５４重量％以上であると分離特性や物理強度が向上し、９１重量％以下であると透水性が向上する三次元網目構造を形成する。またセルロースエステルを９重量％以上含有することで耐ファウリング性が向上し、４６重量％以下に含有すると耐薬品性が向上する。本発明における複合膜は、球状構造の支持膜に分離機能層が積層されるものであるから、界面では層同士が互いに入り込むことで、アンカー効果が実現される。つまり球状構造の支持膜の場合では、平均直径が大きい球状になると広い間隔で支持膜が接合するために、分離機能層が深く球状に入り組む形状で積層される。一方で球状の平均直径が小さくなると接合間隔が狭くなり、界面で相互に入り組んだ形で浅く構造が形成される。ここで三次元網目構造とは、固形分が三次元的に網目状に広がっている構造をいう。また三次元網目構造は網を形成する固形分に仕切られた細孔およびボイドを有する。また、球状構造とは、多数の球状もしくは略球状の固形分が、直接もしくは筋状に固形分を介して連結している構造のこという。 The structure of these composite membranes is the separation of a three-dimensional network structure containing 54 to 91% by weight of a polyvinylidene fluoride resin having a melt viscosity of 3300 Pa · s or more and 9 to 46% by weight of a cellulose ester. It is formed of a functional layer (coat layer) followed by a support film having a spherical structure. When the polyvinylidene fluoride resin is 54% by weight or more, a separation property and physical strength are improved, and when it is 91% by weight or less, a three-dimensional network structure in which water permeability is improved is formed. Further, the fouling resistance is improved by containing 9% by weight or more of cellulose ester, and the chemical resistance is improved by containing it by 46% by weight or less. In the composite membrane according to the present invention, a separation functional layer is laminated on a support membrane having a spherical structure, so that the anchor effect is realized by the layers entering each other at the interface. That is, in the case of a support film having a spherical structure, since the support film is joined at a wide interval when the average diameter becomes a large sphere, the separation functional layer is laminated in a shape that is deeply in a sphere. On the other hand, when the spherical average diameter is reduced, the bonding interval is narrowed, and a shallow structure is formed in an interlaced manner at the interface. Here, the three-dimensional network structure refers to a structure in which the solid content spreads in a three-dimensional network. In addition, the three-dimensional network structure has pores and voids partitioned by solid contents forming a network. The spherical structure refers to a structure in which a large number of spherical or substantially spherical solid components are connected directly or in a streak shape through the solid components.
コート層の最外表面の平均孔径は、好ましくは０．０１μｍ以上である。また、最外表面の平均孔径は、好ましくは０．１μ以下、または０．０３μｍ以下である。最外表面の平均孔径が０．０１μｍ以上であると透水性が向上し、０．１μｍ以下であると分離特性や耐ファウリング性が向上する。ここで、コート層の最外表面の平均孔径は、走査型電子顕微鏡を用いて、複合膜の表面を３００００倍、６００００倍で画像写真撮影し、任意に選んだ計２０カ所の孔の長径と短径を測定した結果を数平均して求めることができる。 The average pore diameter of the outermost surface of the coat layer is preferably 0.01 μm or more. Moreover, the average pore diameter of the outermost surface is preferably 0.1 μm or less or 0.03 μm or less. When the average pore diameter of the outermost surface is 0.01 μm or more, water permeability is improved, and when it is 0.1 μm or less, separation characteristics and fouling resistance are improved. Here, the average pore diameter of the outermost surface of the coating layer is obtained by taking a picture of the surface of the composite membrane at 30000 times and 60000 times using a scanning electron microscope, The result of measuring the minor axis can be obtained by number averaging.
本発明の製造方法によって形成されるコート層の三次元網目構造が分離機能を果たす平均細孔径は、０．０１μｍ以上０．５μｍ以下であることが必要であり、好ましくは０．０３μｍ以上０．３μｍ以下である。平均孔径が０．０１μｍ以上であると膜透過性が向上し、０．５μｍ以下であるとウイルスなどの補足性が向上する。ここで、コート層中の三次元網目構造の平均孔径は、走査型電子顕微鏡を用いて、複合膜の断面を６０００倍、１００００倍で画像写真撮影し、コート層中央の任意に選んだ計２０カ所の孔の長径と短径を測定した結果を数平均して求めることができる。 The average pore diameter at which the three-dimensional network structure of the coat layer formed by the production method of the present invention performs the separation function needs to be 0.01 μm or more and 0.5 μm or less, preferably 0.03 μm or more and 0.00. 3 μm or less. When the average pore size is 0.01 μm or more, the membrane permeability is improved, and when it is 0.5 μm or less, the supplemental properties such as viruses are improved. Here, the average pore diameter of the three-dimensional network structure in the coating layer was 20 images selected at the center of the coating layer by taking a picture of the cross section of the composite film at 6000 times and 10,000 times using a scanning electron microscope. The results of measuring the major and minor diameters of the holes at the places can be obtained by number averaging.
この場合、本発明の製造方法によって形成されるコート層は、最も小さいポリオウイルスの大きさ（約０．０３μｍ）よりも少し大きい孔径を含む分離機能を果たす三次元網目構造が、ある程度以上の厚みをもって存在することになる。実際には、コート層を形成する三次元網目構造にマクロボイドを内包するものであっても、三次元網目構造がかかる性質を有すれば、より好ましくウイルスなどの除去を行えることから、本発明の製造方法によって形成されるコート層内の三次元網目構造が一定の厚みを有することで、ウイルスより小さい孔径でろ過を行うシービング（篩い分け）ろ過で捕捉できない小さい粒子やウイルスを、さらに深い層の細孔内で捕捉する、所謂デプス（深層）ろ過で捕捉していると考えられる。上記の理由によって、本発明の製造方法によって形成されるコート層の厚さは、１０μｍ以上１２０μｍ以下であることが好ましいが、より好ましくは２０μｍ以上１００μｍ以下、さらに好ましくは３０μｍ以上８０μｍ以下である。コート層の厚さが１０μｍ以上であるとウイルス除去性が向上し、厚さ１２０μｍ以下であると透過性能が向上する。ここで、コート層の厚さは、走査型電子顕微鏡を用いて、複合膜の断面を１０００倍、３０００倍で画像写真撮影し、三次元網目構造が観察される範囲の長さを、任意に選んだ計１０カ所で測定した結果を数平均して求めることができる。 In this case, the coating layer formed by the production method of the present invention has a three-dimensional network structure having a separation function including a pore size slightly larger than the size of the smallest poliovirus (about 0.03 μm). Will exist. Actually, even if the macro void is included in the three-dimensional network structure forming the coat layer, if the three-dimensional network structure has such a property, viruses and the like can be removed more preferably. The three-dimensional network structure in the coating layer formed by the manufacturing method of the above has a certain thickness, so that a deeper layer of small particles and viruses that cannot be captured by sieve screening that performs filtration with a pore size smaller than the virus. It is thought that it captures by what is called depth (deep layer) filtration which captures within the pores. For the above reasons, the thickness of the coat layer formed by the production method of the present invention is preferably 10 μm or more and 120 μm or less, more preferably 20 μm or more and 100 μm or less, and further preferably 30 μm or more and 80 μm or less. When the thickness of the coat layer is 10 μm or more, the virus removability is improved, and when the thickness is 120 μm or less, the permeation performance is improved. Here, the thickness of the coating layer is arbitrarily set to the length of the range in which the three-dimensional network structure is observed by taking a picture of the cross section of the composite film at 1000 times and 3000 times using a scanning electron microscope. It is possible to obtain a result obtained by averaging the results measured at 10 selected places.
また本発明に係る支持膜は、厚さは６０μｍ以上５００μｍ以下が好ましく、より好ましくは１２０μｍ以上４５０μｍ以下である。支持膜の厚さが６０μｍ以上であれば外圧による座屈圧力が向上し、５００μｍ以下であると透過性能が向上する。ここで、支持膜の厚さは、走査型電子顕微鏡を用いて、複合膜の断面を１００倍、１０００倍で画像写真撮影し、球状構造が観察される範囲の長さを、任意に選んだ計１０カ所で測定した結果を数平均して求めることができる。 Further, the support membrane according to the present invention preferably has a thickness of 60 μm or more and 500 μm or less, more preferably 120 μm or more and 450 μm or less. If the thickness of the support membrane is 60 μm or more, the buckling pressure due to the external pressure is improved, and if it is 500 μm or less, the permeation performance is improved. Here, the thickness of the support film was arbitrarily selected by using a scanning electron microscope, taking a cross-sectional view of the composite film at 100 times and 1000 times, and photographing the length of the range in which the spherical structure was observed. The results measured at a total of 10 locations can be obtained by number averaging.
さらに、中空糸状であれば、内径が０．１ｍｍφ以上１．６ｍｍφ以下であることが好ましい。 Furthermore, if it is a hollow fiber shape, it is preferable that an internal diameter is 0.1 mmφ or more and 1.6 mmφ or less.
また球状構造の平均直径は０．１μｍ以上５μｍ以下が好ましく、より好ましくは０．５μｍ以上３μｍ以下である。平均直径が０．１μｍ以上の球状構造で構成される場合、透過性能が向上する。また平均直径が５μｍ以下に球状構造で構成される場合、物理的強度が向上する。ここで、球状構造の平均直径は、走査型電子顕微鏡を用いて、複合膜の断面を６０００倍で画像写真撮影し、任意に選んだ計２０カ所の球状の直径を測定した結果を数平均して求めることができる。 The average diameter of the spherical structure is preferably from 0.1 μm to 5 μm, more preferably from 0.5 μm to 3 μm. In the case of a spherical structure having an average diameter of 0.1 μm or more, the transmission performance is improved. Moreover, when it comprises a spherical structure with an average diameter of 5 micrometers or less, physical strength improves. Here, the average diameter of the spherical structure is the number average of the results of measuring the diameter of the spherical shape in a total of 20 locations by taking a picture of the cross section of the composite film at a magnification of 6000 using a scanning electron microscope. Can be obtained.
本発明の複合膜におけるウイルス除去性能は、膜が捕捉すべき適切な性能を有しているか、また欠損があるかを判定するための非破壊性の試験によって定められる性能である。試験方法としては、例えば決まった大きさの指標菌を培養して、ウイルス原液は指標菌を約１．０×１０７ＰＦＵ／ｍｌの濃度を含有する様に蒸留水中で調製し、全ろ過を行う。原液中の菌濃度を分子に、透過液の菌濃度を分母にとり、その比を常用対数で表す。本分離膜のウイルス除去性能は、大きさが約２５ｎｍのバクテリオファージＭＳ−２（Ｂａｃｔｅｒｉｏｐｈａｇｅ ＭＳ−２ ＡＴＣＣ １５５９７−Ｂ１）を用いて行うことができる。ウイルス原液の除去性能評価を、例えば中空糸膜の場合では、中空糸２〜４本程度からなる長さ約２０ｃｍのガラス製モジュールを作製し、温度約２０℃、ろ過差圧約１０ｋＰａ（外圧）の条件でウイルス原液を送液して全ろ過して透過液を得る。任意のろ過量を設定して行うことができる。また平膜の場合では、例えば膜を直径約４３ｍｍに切り出し、円筒のろ過ホルダーにセットして中空糸膜と同様な操作をすることで求めることができる。 The virus removal performance of the composite membrane of the present invention is a performance determined by a non-destructive test for determining whether the membrane has an appropriate performance to be captured and whether there is a defect. As a test method, for example, indicator bacteria of a predetermined size are cultured, and the virus stock solution is prepared in distilled water so that the indicator bacteria contain a concentration of about 1.0 × 10 7 PFU / ml. Do. The concentration of bacteria in the stock solution is taken as the numerator, the concentration of bacteria in the permeate as the denominator, and the ratio is expressed as a common logarithm. The virus removal performance of this separation membrane can be performed using bacteriophage MS-2 (Bacteriophage MS-2 ATCC 15597-B1) having a size of about 25 nm. For example, in the case of a hollow fiber membrane, a glass module having a length of about 20 cm consisting of about 2 to 4 hollow fibers is produced, and a temperature of about 20 ° C. and a filtration differential pressure of about 10 kPa (external pressure) are evaluated. Under conditions, the virus stock solution is fed and completely filtered to obtain a permeate. An arbitrary filtration amount can be set and performed. In the case of a flat membrane, for example, the membrane can be obtained by cutting out the membrane to a diameter of about 43 mm, setting it in a cylindrical filtration holder, and performing the same operation as the hollow fiber membrane.
本発明における純水透過性能は、供給水と透過水を区分する容器（モジュール）内に膜を組み込み、印加した圧力のものとに透過水量を測定することで評価できる。実質的には供給水に微粒子を含まない純水ないしは蒸留水を用いて行う。例えば中空糸膜の場合では、中空糸２〜４本程度からなる長さ約２０ｃｍのガラス製モジュールを作製し、温度約２０℃、ろ過差圧約１０ｋＰａ（外圧）の条件で純水を送液して全ろ過して行うことができる。また平膜の場合では、例えば膜を直径約４３ｍｍに切り出し、円筒のろ過ホルダーにセットして中空糸膜と同様な操作をすることで求めることができる。 The pure water permeation performance in the present invention can be evaluated by incorporating a membrane in a container (module) that separates supply water and permeate and measuring the amount of permeate with an applied pressure. In practice, pure water or distilled water that does not contain fine particles is used in the feed water. For example, in the case of a hollow fiber membrane, a glass module having a length of about 20 cm consisting of about 2 to 4 hollow fibers is prepared, and pure water is fed under conditions of a temperature of about 20 ° C. and a filtration differential pressure of about 10 kPa (external pressure). And can be completely filtered. In the case of a flat membrane, for example, the membrane can be obtained by cutting out the membrane to a diameter of about 43 mm, setting it in a cylindrical filtration holder, and performing the same operation as the hollow fiber membrane.
本発明における破断強度・破断伸度は、物性試験機を用いて試験長の長さ方向に引っ張った際の荷重−伸びの曲線が示す破断した時の強度・伸度を測定する。これらの測定については、引張試験機（（株）ボールドウィン製ＴＥＮＳＩＬＯＮ（登録商標）／ＲＴＧ−１２１０）を用いて、水で湿潤させた複合膜を試験長５０ｍｍ、フルスケール５ｋｇの荷重でクロスヘッドスピード５０ｍｍ／分にて測定し、複合膜を変えて１０回実施した破断強力・伸度の測定結果から数平均することによって求めることができる。また破断強度は、破断強力（Ｎ）を複合膜の単位断面積（ｍｍ２）における破断強度（Ｎ／ｍｍ２＝Ｐａ）として求めることができる。 The breaking strength and breaking elongation in the present invention are determined by measuring the strength and elongation at the time of breaking indicated by a load-elongation curve when pulled in the length direction of the test length using a physical property tester. For these measurements, using a tensile tester (TENSILON (registered trademark) / RTG-1210 manufactured by Baldwin Co., Ltd.), the composite membrane wetted with water was tested for a test length of 50 mm and a full scale load of 5 kg. It can be obtained by measuring at 50 mm / min and by number averaging from the measurement results of the breaking strength / elongation carried out 10 times by changing the composite film. In addition, the breaking strength can be obtained by breaking strength (N) as breaking strength (N / mm 2 = Pa) in a unit sectional area (mm 2 ) of the composite membrane.
本発明の複合膜は、コート層の最外表面に細かい孔隙形成と、セルロースエステルによる親水性の効果により、優れた耐汚れ性を示すことも特徴である。耐汚れ性について以下に説明する。一般的な精密ろ過膜や限外ろ過膜を用いた水処理方法では、ろ過工程において被処理水中の濁質成分などを阻止することによって膜面細孔の閉塞が進み、ろ過抵抗が上昇する。このために物理洗浄工程では、膜面付着した濁質成分などを膜細孔から除去するために、透過水側から膜外表面に向けて透過水や圧縮空気などの流体を流す逆圧洗浄を施す。この物理洗浄工程において、阻止した成分の一部が膜から剥離され、ろ過抵抗が下がる。しかしながら膜面で阻止した全ての成分を完全に除去することは難しく、膜に残る付着成分によってろ過抵抗は運転の継続と共に上昇を続けることになる。最終的には化学薬品を用いた薬液洗浄を施すが、ろ過抵抗が回復しない場合には膜モジュール自体を交換することになる。このような長期的なろ過抵抗の上昇（度）を抑え、定流量（安定）運転を可能にするには、１回のろ過工程におけるろ過抵抗の上昇を抑制すると共に、物理洗浄工程を含む連続運転におけるろ過抵抗の上昇を抑制することが求められる。つまり、長期の安定運転には物理洗浄の回復性を含んだろ過抵抗値上昇の程度を下げることが重要となる。連続運転におけるろ過抵抗の上昇は、ろ過抵抗上昇度として以下のような手法で定量的に表される。 The composite membrane of the present invention is also characterized by excellent stain resistance due to the formation of fine pores on the outermost surface of the coat layer and the hydrophilic effect of the cellulose ester. The stain resistance will be described below. In a water treatment method using a general microfiltration membrane or an ultrafiltration membrane, blocking of turbid components and the like in the water to be treated is prevented in the filtration step, so that the membrane surface pores are blocked and the filtration resistance is increased. For this reason, in the physical cleaning process, in order to remove turbid components adhering to the membrane surface from the membrane pores, back pressure cleaning is performed by flowing a fluid such as permeate or compressed air from the permeate side toward the outer surface of the membrane. Apply. In this physical cleaning process, a part of the blocked components is peeled off from the membrane, and the filtration resistance is lowered. However, it is difficult to completely remove all the components blocked on the membrane surface, and the filtration resistance continues to increase as the operation continues due to the adhering components remaining on the membrane. Finally, chemical cleaning using chemicals is performed, but if the filtration resistance does not recover, the membrane module itself is replaced. In order to suppress such a long-term increase (degree) in filtration resistance and enable a constant flow rate (stable) operation, the increase in filtration resistance in a single filtration step is suppressed, and a continuous process including a physical cleaning step is included. It is required to suppress an increase in filtration resistance during operation. In other words, for long-term stable operation, it is important to reduce the degree of increase in the filtration resistance value including the recoverability of physical cleaning. The increase in filtration resistance in continuous operation is quantitatively represented by the following technique as the degree of filtration resistance increase.
ろ過工程では、ろ過圧力１００ｋＰａで透過水量０．０６５ｍ３／ｍ２まで実施し、次いで逆圧洗浄工程では、逆洗圧力１５０ｋＰａで０．００２５ｍ３／ｍ２の水を透過側から膜外表面に向けて流すことを行い、再度、ろ過工程と逆圧洗浄工程をサイクルで３０回繰り返す。総ろ過水量を横軸に、算出したろ過抵抗を縦軸にプロットする。ろ過工程において一定時間あたりに得られる透過水量を記録し、ろ過圧力１００ｋＰａを、その透過水量で除することにより、その時におけるろ過抵抗値を求める。このプロットにおいて、１１回目〜３０回目のろ過工程開始時のろ過抵抗２０点を結んだ直線の傾きをろ過抵抗上昇度とする。ただし、２０点が直線上に乗らない場合には、線形近似で直線の傾きを求めてろ過抵抗上昇度とする。通常、ろ過工程と逆圧洗浄工程を繰り返す膜ろ過運転において、ろ過抵抗上昇度が小さいほど耐汚れ性に優れ、長期的に安定運転できる優れた膜と云える。本発明の複合膜において、前記手法によって算出されるろ過抵抗上昇度は、２×１０１２／ｍ２以下が好ましく、１×１０１２／ｍ２以下がより好ましい。 In the filtration step, the permeated water amount is 0.065 m 3 / m 2 at a filtration pressure of 100 kPa, and then in the back pressure washing step, 0.0025 m 3 / m 2 of water is passed from the permeate side to the outer surface of the membrane at a back washing pressure of 150 kPa. The filtration process and the back pressure washing process are repeated 30 times in the cycle. The total filtration water amount is plotted on the horizontal axis, and the calculated filtration resistance is plotted on the vertical axis. The permeated water amount obtained per fixed time in the filtration step is recorded, and the filtration resistance value at that time is obtained by dividing the filtration pressure 100 kPa by the permeated water amount. In this plot, the slope of the straight line connecting 20 points of filtration resistance at the start of the 11th to 30th filtration steps is defined as the increase in filtration resistance. However, when 20 points are not on the straight line, the slope of the straight line is obtained by linear approximation to obtain the degree of increase in filtration resistance. Usually, in a membrane filtration operation in which the filtration step and the back pressure washing step are repeated, the smaller the degree of increase in filtration resistance, the better the stain resistance and the better the membrane that can be stably operated over the long term. In the composite membranes of the present invention, filtration resistance increases degree calculated by said method is preferably 2 × 10 12 / m 2 or less, more preferably 1 × 10 12 / m 2 or less.
以下に具体的な実施例を挙げて本発明を説明するが、本発明はこれら実施例により何ら限定されるものではない。ここで本発明の複合膜に関する物性値、形態は以下の方法で測定した。 Hereinafter, the present invention will be described with reference to specific examples, but the present invention is not limited to these examples. Here, the physical property value and form of the composite membrane of the present invention were measured by the following methods.
（１）溶融粘度
溶融粘度は、ＡＳＴＭ Ｄ３８３５／２３２℃に剪断速度１００秒−１の条件下で測定した。
(1) Melt viscosity The melt viscosity was measured under the conditions of ASTM D3835 / 232 ° C and a shear rate of 100 sec- 1 .
（２）溶液粘度
溶液粘度は、溶液を６０℃に保温して回転式デジタル粘度計（型式：ＰＶ-II＋Ｐｒｏ，米国ブルックフィールド社製）で測定した。
(2) Solution viscosity The solution viscosity was measured with a rotary digital viscometer (model: PV-II + Pro, manufactured by Brookfield, USA) while keeping the solution at 60 ° C.
（３）ウイルス除去性能
ウイルス原液は、大きさが約２５ｎｍのバクテリオファージＭＳ−２（Ｂａｃｔｅｒｉｏｐｈａｇｅ ＭＳ−２ ＡＴＣＣ １５５９７−Ｂ１）を約１．０×１０７ＰＦＵ／ｍｌの濃度を含有する様に蒸留水中で調製した。ここで蒸留水は純水製造装置オートスチル（ヤマト科学製）の蒸留水を１２１℃で２０分間高圧蒸気滅菌したものを用いた。ウイルス原液の除去性能評価は、中空糸膜２〜４本程度からなる長さ約２０ｃｍのガラス製ミニモジュールを作製し、温度約２０℃、ろ過差圧約１０ｋＰａ（外圧）の条件でウイルス原液を送液して、全ろ過した。ろ過液の採取は、初期とサンプルの膜面積換算で総ろ過水量が約０．１３ｍ３／ｍ２に達した時点で２回目のろ過液を採取した。まず、ろ過した初期のろ過の約１０ｍｌを破棄した後、ろ過液を約５ｍｌ採取し、引き続き、サンプルの膜面積換算で総ろ過水量が約０．１３ｍ３／ｍ２に達した時点のろ過液を約５ｍｌ採取した。これらのろ過液を０〜１０００倍に蒸留水で希釈した。Ｏｖｅｒｌａｙ ａｇａｒ ａｓｓａｙ、Ｓｔａｎｄａｒｄ Ｍｅｔｈｏｄ ９２１１−Ｄ（ＡＰＨＡ、１９９８、Ｓｔａｎｄａｒｄ ｍｅｔｈｏｄｓ ｆｏｒ ｔｈｅ ｅｘａｍｉｎａｔｉｏｎ ｏｆ ｗａｔｅｒ ａｎｄ ｗａｓｔｅｗａｔｅｒ, １８ｔｈ ｅｄ．）の方法に基づいて、希釈した透過液１ｍｌを検定用シャーレに接種し、プラックを計数することによってバクテリオファージＭＳ−２の濃度を求めた。
(3) Virus removal performance The virus stock solution is distilled so that bacteriophage MS-2 (Bacteriophage MS-2 ATCC 15597-B1) having a size of about 25 nm contains a concentration of about 1.0 × 10 7 PFU / ml. Prepared in water. The distilled water used here was distilled water from a pure water production apparatus Auto Still (manufactured by Yamato Kagaku) and subjected to high-pressure steam sterilization at 121 ° C. for 20 minutes. To evaluate the removal performance of the virus stock solution, a glass mini-module with a length of about 20 cm consisting of about 2 to 4 hollow fiber membranes was prepared, and the virus stock solution was sent under conditions of a temperature of about 20 ° C. and a filtration differential pressure of about 10 kPa (external pressure). And then filtered completely. The filtrate was collected for the second time when the total filtrate amount reached about 0.13 m 3 / m 2 in terms of the membrane area of the sample at the beginning. First, after discarding about 10 ml of the filtered initial filtration, about 5 ml of the filtrate was collected, and then the filtrate when the total filtrate water amount reached about 0.13 m 3 / m 2 in terms of the membrane area of the sample. About 5 ml of was collected. These filtrates were diluted 0 to 1000 times with distilled water. Based on the method of Overlay agar assay, Standard Method 9211-D (APHA, 1998, Standard methods for the examination of water and wastewater, 18th ed.) To determine the concentration of bacteriophage MS-2.
ウイルスの除去性能は、初期ろ過液、及び総ろ過水量が約０．１３ｍ３／ｍ２に達した時点のろ過液を、それぞれ評価サンプル１（初期ろ過液）、及び評価サンプル２（総ろ過水量が約０．１３ｍ３／ｍ２に達した時点のろ過液）として対数で表した。例えば２ｌｏｇとは２ｌｏｇ１０のことであり、残存濃度が１００分の１であることを意味する。また透過液中にプラックがまったく計測されない場合、＞７ｌｏｇとした。 The removal performance of the virus is the evaluation sample 1 (initial filtrate) and the evaluation sample 2 (total filtrate amount), respectively, when the initial filtrate and the filtrate when the total filtrate amount reached about 0.13 m 3 / m 2. Is a logarithm as a filtrate at the time when it reached about 0.13 m 3 / m 2 . For example, 2 log means 2 log 10 and means that the residual concentration is 1/100. Further, when no plaque was measured in the permeate, it was set to> 7 log.
（４）純水透過性能
透水性能は、複合膜２〜４本程度からなる長さ約２０ｍｍのガラス製ミニモジュールを作製し、温度２５℃、ろ過差圧１６ｋＰａ（外圧）の条件で蒸留水を送液して全ろ過を行い、一定時間の透過水量（ｍ３）を測定して得た値を、単位時間（ｈｒ）、単位有効膜面積（ｍ２）、５０ｋＰａにおける値に換算して算出した。
(4) Pure water permeation performance Water permeation performance is about 20 mm long glass mini-module consisting of about 2 to 4 composite membranes, and distilled water is used under conditions of temperature 25 ° C and filtration differential pressure 16 kPa (external pressure). The value obtained by measuring the amount of permeated water (m 3 ) for a certain period of time by sending the solution and performing total filtration is calculated by converting it to a value in unit time (hr), unit effective membrane area (m 2 ), and 50 kPa. did.
（５）破断強度・伸度
引張試験機（（株）ボールドウィン製ＴＥＮＳＩＬＯＮ（登録商標）／ＲＴＧ−１２１０）を用いて、水で湿潤させた複合膜を試験長５０ｍｍ、フルスケール５ｋｇの荷重でクロスヘッドスピード５０ｍｍ／分にて測定し、複合膜を変えて１０回実施した破断強力・伸度の測定結果から数平均することで求めた。また破断強度は、破断強力（Ｎ）を複合膜の単位断面積（ｍｍ２）における破断強度（Ｎ／ｍｍ２＝Ｐａ）として求めた。
(5) Breaking strength / elongation Using a tensile tester (TENSILON (registered trademark) / RTG-1210 manufactured by Baldwin Co., Ltd.), the composite membrane wetted with water is crossed with a test length of 50 mm and a load of 5 kg full scale. The measurement was performed at a head speed of 50 mm / min, and the number was averaged from the measurement results of the breaking strength / elongation performed 10 times by changing the composite film. In addition, the breaking strength was determined as the breaking strength (N / mm 2 = Pa) at the unit cross-sectional area (mm 2 ) of the composite membrane.
（６）コート層の厚さ
走査型電子顕微鏡を用いて、複合膜の断面を３０００倍で画像写真撮影し、三次元網目構造が観察される範囲の長さを、任意に選んだ計１０カ所で測定した結果を数平均して求めた。
(6) Coat layer thickness Using a scanning electron microscope, the cross-section of the composite film was photographed at 3000 times, and the length of the range in which the three-dimensional network structure was observed was arbitrarily selected in a total of 10 locations. The results measured in were obtained by averaging the results.
（７）支持膜の厚さ
走査型電子顕微鏡を用いて、複合膜の断面を１００倍、１０００倍で画像写真撮影し、球状構造が観察される範囲の長さを、任意に選んだ計１０カ所で測定した結果を数平均して求めた。
(7) Thickness of the support film Using a scanning electron microscope, the composite film was photographed at 100 times and 1000 times, and the length of the range in which the spherical structure was observed was arbitrarily selected. The results measured at the places were obtained by number averaging.
（８）コート層外表面の平均孔径
走査型電子顕微鏡を用いて、複合膜の表面を３００００倍、６００００倍で画像写真撮影し、任意に選んだ計２０カ所の孔の長径と短径を測定した結果を数平均して求めた。
(8) Average pore diameter on the outer surface of the coating layer Using a scanning electron microscope, the surface of the composite film was photographed at 30000 times and 60000 times, and the major and minor diameters of 20 arbitrarily selected pores were measured. The obtained results were obtained by number averaging.
（９）三次元網目構造の平均孔径
走査型電子顕微鏡を用いて、複合膜の断面を６０００倍、１００００倍で画像写真撮影し、コート層中央付近で任意に選んだ計２０カ所の孔の長径と短径を測定した結果を数平均して求めた。
(9) Average pore diameter of three-dimensional network structure Using a scanning electron microscope, the cross-section of the composite film was photographed at 6000x and 10000x, and the major diameters of a total of 20 pores arbitrarily selected near the center of the coating layer The number average of the results of measuring the minor axis was obtained.
（１０）球状構造の平均直径
走査型電子顕微鏡を用いて、複合膜の断面を６０００倍で画像写真撮影し、任意に選んだ計２０カ所の球状の長径と短径を測定した結果を数平均して求めた。
(10) Average diameter of spherical structure Using a scanning electron microscope, the cross-section of the composite film was photographed at a magnification of 6000 times, and a number average of the results of measuring the spherical major axis and minor axis at a total of 20 locations selected arbitrarily. And asked.
（１１）複合膜（中空糸膜）の平均外径／内径
走査型電子顕微鏡を用いて、中空糸状の複合膜の断面を６０倍、１００倍で画像写真撮影し、任意に選んだ計１０カ所の外径及内径の長径と短径を測定した結果を数平均して求めた。
(11) Average outer diameter / inner diameter of composite membrane (hollow fiber membrane) Using a scanning electron microscope, the cross-section of the hollow fiber-like composite membrane was photographed at 60 times and 100 times, and a total of 10 arbitrarily selected locations The results of measuring the major and minor diameters of the outer and inner diameters were obtained by number averaging.
（１２）ろ過抵抗上昇度
中空糸膜６本からなる長さ約１５ｃｍの中空糸膜の両端部が開口したガラス製ミニモジュールを作製した（図４）。ステンレス製加圧タンク（ＡＤＶＡＮＴＥＣ ＰＲＥＳＳＵＲＥ ＶＥＳＳＥＬ ＤＶ−１０、容量１０Ｌ）に原水を入れ（以下に原水タンクと云う）、ステンレス製加圧タンク（ＡＤＶＡＮＴＥＣ ＰＲＥＳＳＵＲＥ ＶＥＳＳＥＬ ＤＶ−４０、容量４０Ｌ））に純水製造装置オートスチル（ヤマト科学製）の蒸留水を１２１℃で２０分間高圧蒸気滅菌した蒸留水を入れた（以下に蒸留水タンクと云う）。なお原水には、琵琶湖水（濁度１．０ＮＴＵ以下，ＴＯＣ（全有機炭素）１．２ｍｇ／Ｌ，カルシウム濃度１５ｍｇ／Ｌ，ケイ素濃度０．５，マンガン濃度０．０１ｍｇ／Ｌ以下，鉄濃度０．０１ｍｇ／以下）を用いた。
(12) Increase in filtration resistance A glass mini-module having both ends of a hollow fiber membrane having a length of about 15 cm consisting of six hollow fiber membranes was prepared (FIG. 4). Raw water is put into a stainless steel pressurized tank (ADVANTEC PRESSURE VESSEL DV-10, capacity 10L) (hereinafter referred to as raw water tank), and pure water is produced in a stainless steel pressurized tank (ADVANTEC PRESSURE VESSEL DV-40, capacity 40L). Distilled water obtained by autoclaving distilled water from a device auto still (manufactured by Yamato Kagaku) at 121 ° C. for 20 minutes was added (hereinafter referred to as a distilled water tank). For raw water, Lake Biwa water (turbidity 1.0 NTU or less, TOC (total organic carbon) 1.2 mg / L, calcium concentration 15 mg / L, silicon concentration 0.5, manganese concentration 0.01 mg / L or less, iron concentration) 0.01 mg / below) was used.
評価装置の構成は、ガラス製ミニモジュールのＡ、Ｄの端部に接続型２方コック（ＰＴＦＥ製）、Ｂ、Ｃの端部に接続型３方コック（ＰＴＦＥ製）を取り付けた。ガラス製ミニモジュールのＢ端部の３方コックと原水タンク供給口を内径φ６ｍｍのＰＴＦＥチューブで接続し、原水供給ラインとした。また同様のチューブでＡ，Ｃ端部のコックと蒸留水タンク供給口に接続して、蒸留水供給ラインとした。まずＡ端部とＣ端部のコックを閉止し、原水タンク内に１００ｋＰａに調整した圧縮空気を印加し、Ｂ端部とＤ端部のコックを開くことで原水タンクからガラス製ミニモジュール内に原水（湖水）を供給して外圧全ろ過を行うろ過工程とした。 The configuration of the evaluation apparatus was such that a connection type two-way cock (made of PTFE) was attached to the ends of glass mini-modules A and D, and a connection type three-way cock (made of PTFE) was attached to the ends of B and C. The three-way cock at the B end of the glass mini-module and the raw water tank supply port were connected with a PTFE tube having an inner diameter of φ6 mm to form a raw water supply line. A similar tube was connected to the cocks at the ends of A and C and a distilled water tank supply port to form a distilled water supply line. First, the A and C end cocks are closed, compressed air adjusted to 100 kPa is applied to the raw water tank, and the B and D end cocks are opened to bring the raw water tank into the glass mini-module. It was set as the filtration process which supplies raw | natural water (lake water) and performs external pressure total filtration.
透過水の重量をパソコンに接続した電子天秤（ＡＮＤ ＨＦ−６０００）で５秒毎に測定し、連続記録プログラムＡＮＤ ＲｓＣｏｍ ｖｅｒ．２．４０を用いて記録した。本実験で得られるデータは５秒あたりの透過水重量（ｇ）から、ろ過抵抗を以下に示す式を用いて算出した。 The weight of the permeated water was measured every 5 seconds with an electronic balance (AND HF-6000) connected to a personal computer, and the continuous recording program AND RsCom ver. Recorded using 2.40. The data obtained in this experiment was calculated from the permeated water weight (g) per 5 seconds using the following formula for filtration resistance.
ろ過抵抗（１／ｍ） ＝ろ過圧力（ｋＰａ）×１０３ ×５×膜面積（ｍ２）×１０６／（粘度（Ｐａ・ｓ）×（５秒あたりの透過水重量）×密度（ｇ／ｃｍ３））
透過水が流量０．０００２５（ｍ３／ｍ２）になった時点で、ガラス製ミニモジュールのＢ端部の原水ライン３方コック、及びＤ端部の２方コックを閉として原水供給を停止した。引き続き、蒸留水タンク内に１５０ｋＰａに調整した圧縮空気を印加し、逆洗水としてＡ端部の２方コックを開いて蒸留水を中空糸内部に流し、Ｃ端部の３方コックを排出側に開いて逆洗排水が１０ｍｌになるまで系外に流して逆洗工程とした。以上のろ過工程と逆洗工程を一つの操作として、設置モジュール対して３０回連続して実施し、総ろ過水量を横軸に、算出したろ過抵抗を縦軸にプロットした。
Filtration resistance (1 / m) = filtration pressure (kPa) × 10 3 × 5 × membrane area (m 2 ) × 10 6 / (viscosity (Pa · s) × (permeated water weight per 5 seconds) × density (g / Cm 3 ))
When the permeate reaches 0.00025 (m 3 / m 2 ), the raw water supply is stopped by closing the three-way cock at the B end of the glass mini-module and the two-way cock at the D end. did. Subsequently, compressed air adjusted to 150 kPa was applied to the distilled water tank, the two-way cock at the A end was opened as backwash water, distilled water was allowed to flow inside the hollow fiber, and the three-way cock at the C end was discharged from the discharge side. The backwashing process was carried out by flowing it out of the system until the backwash drainage reached 10 ml. The above filtration step and backwashing step were carried out 30 times continuously for the installation module as one operation, and the total filtration water amount was plotted on the horizontal axis and the calculated filtration resistance was plotted on the vertical axis.
ここでプロットの開始は、各回のろ過開始３０秒後からとした。また、ろ過抵抗の上昇に伴い透水量が減少するため、５秒ごとの増加量の絶対値が減少する。ろ過抵抗は増加量から前記式に従って算出するため、増加量が減少するとそのばらつきが算出されるろ過抵抗に与える影響が大きくなる。従って、透水量の減少が著しい場合には、適宜作成したグラフの移動平均近似をとってグラフを修正した。 Here, the plot was started 30 seconds after the start of each filtration. Moreover, since the water permeation amount decreases as the filtration resistance increases, the absolute value of the increase amount every 5 seconds decreases. Since the filtration resistance is calculated from the increase amount according to the above formula, when the increase amount decreases, the variation has a greater effect on the calculated filtration resistance. Therefore, when the decrease in water permeability was significant, the graph was corrected by taking a moving average approximation of the graph created as appropriate.
ろ過実験の結果から作成した総ろ過水量−ろ過抵抗のグラフ、場合によっては前記グラフの移動平均近似をとったグラフにおいて、総ろ過水量とろ過抵抗の関係から、１１〜３０回目のろ過工程開始時のろ過抵抗２０点を結んだ直線の傾きをろ過抵抗上昇度とした。ただし、２０点が直線上に乗らない場合には、線形近似で直線の傾きを求めてろ過抵抗上昇度（×１０１２／ｍ２）とした。 In the graph of the total filtered water amount-filtration resistance created from the results of the filtration experiment, and in some cases the moving average approximation of the graph, from the relationship between the total filtered water amount and the filtration resistance, the 11th to 30th filtration process start time The slope of the straight line connecting the 20 filtration resistances was defined as the increase in filtration resistance. However, when 20 points did not lie on the straight line, the slope of the straight line was obtained by linear approximation to obtain the degree of increase in filtration resistance (× 10 12 / m 2 ).
＜実施例１＞
重量平均分子量４２万のフッ化ビニリデンホモポリマー（株式会社クレハ製、ＫＦポリマーＴ＃１３００）３８重量％とγ−ブチロラクトン（三菱化学株式会社製：以下同じ）６２重量％を１５０℃で溶解して支持膜用溶液を得た。また溶融粘度測定値が４７００Ｐａ・ｓのフッ化ビニリデンホモポリマー（アルケマ社製，ｋｙｎａｒ（登録商標）ＨＳＶ９００，カタログ記載の溶融粘度３３００〜５５００Ｐａ・ｓ）１４．５重量％、セルロースアセテート（イーストマンケミカル社、ＣＡ４３５−７５５：三酢酸セルロース、ＣＡ３９８−３：二酢酸セルロース）４重量％、Ｎ−メチル−２−ピロリドンを８１．５重量％の割合として温度１５０℃で溶解し、コート溶液を得た。この支持膜用溶液を二重管状紡糸ノズルの外側スリットから、γ−ブチロラクトン８５重量％水溶液を二重管状紡糸ノズルの中心パイプから共に同心円状に押し出し、凝固温度が１０℃のγ−ブチロラクトン８５重量％水溶液中で固化させた後、１．５倍の延伸工程、脱溶媒工程、乾燥工程を経て支持膜を得た。この支持膜をコートノズル内に導入し、一方で得られたコート溶液をコートノズルに供給して支持膜をコーティングしながら引き出し、その後２５℃の水中で凝固させる工程、脱溶媒工程を経て中空糸状の複合膜（以後、複合中空糸膜と呼ぶ。）を得た。
<Example 1>
38% by weight of vinylidene fluoride homopolymer having a weight average molecular weight of 420,000 (manufactured by Kureha Co., Ltd., KF polymer T # 1300) and 62% by weight of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) are dissolved at 150 ° C. A support membrane solution was obtained. Further, a vinylidene fluoride homopolymer having a melt viscosity measurement value of 4700 Pa · s (Arkema, kynar (registered trademark) HSV900, melt viscosity 3300-5500 Pa · s described in the catalog) 14.5% by weight, cellulose acetate (Eastman Chemical) Co., CA435-755: cellulose triacetate, CA398-3: cellulose diacetate) 4 wt%, N-methyl-2-pyrrolidone was dissolved at a temperature of 150 ° C. at a rate of 81.5 wt% to obtain a coating solution. . This support membrane solution was extruded from the outer slit of the double tubular spinning nozzle, and an 85% by weight aqueous solution of γ-butyrolactone was extruded concentrically from the center pipe of the double tubular spinning nozzle, and the solidification temperature was 10 ° C. and 85 weight of γ-butyrolactone. After solidifying in an aqueous solution, a support film was obtained through a 1.5-fold stretching process, a solvent removal process, and a drying process. This support membrane is introduced into the coat nozzle, while the obtained coating solution is supplied to the coat nozzle and pulled out while coating the support membrane, and then solidified in water at 25 ° C., followed by a solvent removal step to form a hollow fiber A composite membrane (hereinafter referred to as a composite hollow fiber membrane) was obtained.
得られた複合中空糸膜の構造形態は、外径が１４２０μｍ、内径が７５４μｍ、コート層の平均厚さが７５μｍで一部にマクロボイドを内包していた。コート層の最外表面の平均孔径が０．０３μｍ、コート層の三次元網目構造の平均孔径が０．５μｍ、支持膜の球状（構造）の平均直径が２．６μｍであった。純水透過性能が０．２６ｍ３／ｍ２／ｈｒ、ウイルス除去性能は、初期値で＞７ｌｏｇ、総ろ過水量が約０．１３ｍ３／ｍ２に達した時点の値で＞７ｌｏｇのウイルスが洩れない除去性能を示した。糸物性値は破断強度が１３．４ＭＰａ、破断伸度５１％であり、琵琶湖水におけるろ過抵抗上昇度が０．５４×１０１２／ｍ２を示す、耐汚れ性に優れた複合中空糸膜であった。なお評価結果を表１にまとめた。 The obtained composite hollow fiber membrane had an outer diameter of 1420 μm, an inner diameter of 754 μm, an average thickness of the coat layer of 75 μm, and partly encapsulated macrovoids. The average pore diameter of the outermost surface of the coat layer was 0.03 μm, the average pore diameter of the three-dimensional network structure of the coat layer was 0.5 μm, and the average diameter of the spherical (structure) of the support membrane was 2.6 μm. Pure water permeation performance is 0.26 m 3 / m 2 / hr, virus removal performance is> 7 log at the initial value, and> 7 log virus at the time when the total filtrate reaches about 0.13 m 3 / m 2. The removal performance which does not leak is shown. The yarn property value is a composite hollow fiber membrane having excellent soil resistance, having a breaking strength of 13.4 MPa, a breaking elongation of 51%, and an increase in filtration resistance in Lake Biwa water of 0.54 × 10 12 / m 2. there were. The evaluation results are summarized in Table 1.
＜実施例２＞
実施例１と同様の支持膜溶液を用いて、製膜紡糸した支持膜をコートノズル内に導入し、一方で溶融粘度測定値が４７００Ｐａ・ｓのフッ化ビニリデンホモポリマー（アルケマ社製，ｋｙｎａｒ（登録商標）ＨＳＶ９００，カタログ記載の溶融粘度３３００〜５５００Ｐａ・ｓ）１６重量％、セルロースアセテート（イーストマンケミカル社、ＣＡ４３５−７５Ｓ：三酢酸セルロース、ＣＡ３９８−３：二酢酸セルロース）４．５重量％、Ｎ−メチル−２−ピロリドンを７９．５重量％の割合として温度１５０℃で溶解したコート溶液を、コートノズルに供給して支持膜をコーティングしながら引き出し、その後３５℃の２％ＮＭＰ水溶液中で凝固させる工程、脱溶媒工程を経て複合中空糸膜を得た。
<Example 2>
Using the same support membrane solution as in Example 1, a membrane-spun support membrane was introduced into a coat nozzle, while a vinylidene fluoride homopolymer having a melt viscosity measurement value of 4700 Pa · s (manufactured by Arkema, kynar ( (Registered trademark) HSV900, melt viscosity 3300-5500 Pa · s described in the catalog 16% by weight, cellulose acetate (Eastman Chemical Co., CA435-75S: cellulose triacetate, CA398-3: cellulose diacetate) 4.5% by weight, A coating solution in which N-methyl-2-pyrrolidone is dissolved at a temperature of 150 ° C. at a ratio of 79.5% by weight is supplied to the coating nozzle and pulled out while coating the support film, and then in a 2% NMP aqueous solution at 35 ° C. A composite hollow fiber membrane was obtained through a solidification step and a solvent removal step.
得られた複合中空糸膜の構造形態は、外径が１３９０μｍ、内径が７５０μｍ、コート層の平均厚さが６０μｍ、コート層の最外表面の平均孔径が０．０３μｍ、コート層の三次元網目構造の平均孔径が０．４μｍ、支持膜の球状（構造）の平均直径が２．６μｍであった。純水透過性能が０．２５ｍ３／ｍ２／ｈｒ、ウイルス除去性能は、初期値で＞７ｌｏｇ、総ろ過水量が約０．１３ｍ３／ｍ２に達した時点の値で＞７ｌｏｇのウイルスが洩れない除去性能を示した。糸物性値は、破断強度が１４．０ＭＰａ、破断伸度４５％であり、琵琶湖水におけるろ過抵抗上昇度は、０．２８×１０１２／ｍ２を示す、耐汚れ性に優れた複合中空糸膜であった。なお評価結果を表１にまとめた。 The structure of the obtained composite hollow fiber membrane has an outer diameter of 1390 μm, an inner diameter of 750 μm, an average thickness of the coat layer of 60 μm, an average pore diameter of the outermost surface of the coat layer of 0.03 μm, and a three-dimensional network of the coat layer The average pore diameter of the structure was 0.4 μm, and the average diameter of the spherical shape (structure) of the support membrane was 2.6 μm. Pure water permeation performance is 0.25 m 3 / m 2 / hr, virus removal performance is> 7 log at the initial value, and> 7 log virus at the time when the total filtered water volume reaches about 0.13 m 3 / m 2. The removal performance which does not leak is shown. Yarn physical property values are a composite hollow fiber excellent in soil resistance, having a breaking strength of 14.0 MPa, a breaking elongation of 45%, and an increase in filtration resistance in Lake Biwa water of 0.28 × 10 12 / m 2. It was a membrane. The evaluation results are summarized in Table 1.
＜実施例３＞
実施例１と同様の支持膜溶液を用いて、製膜紡糸した支持膜をコートノズル内に導入し、一方で溶融粘度測定値が４７００Ｐａ・ｓのフッ化ビニリデンホモポリマー（アルケマ社製，ｋｙｎａｒ（登録商標）ＨＳＶ９００，カタログ記載の溶融粘度３３００〜５５００Ｐａ・ｓ）１８重量％、セルロースアセテート（イーストマンケミカル社、ＣＡ４３５−７５Ｓ：三酢酸セルロース、ＣＡ３９８−３：二酢酸セルロース）５重量％、Ｎ−メチル−２−ピロリドンを７７重量％の割合として温度１５０℃で溶解し、コート溶液を得た。実施例１と同様の支持膜用溶液を用いて支持膜を得た。この支持膜をコートノズル内に供給し、一方で得られたコート溶液を供給して支持膜をコーティングしながら引き出し、その後３５℃の２％ＮＭＰ水溶液中で凝固させる工程、脱溶媒工程を経て複合中空糸膜を得た。
<Example 3>
Using the same support membrane solution as in Example 1, a membrane-spun support membrane was introduced into a coat nozzle, while a vinylidene fluoride homopolymer having a melt viscosity measurement value of 4700 Pa · s (manufactured by Arkema, kynar ( (Registered trademark) HSV900, melt viscosity 3300-5500 Pa · s described in catalog 18% by weight, cellulose acetate (Eastman Chemical Co., CA435-75S: cellulose triacetate, CA398-3: cellulose diacetate) 5% by weight, N- Methyl-2-pyrrolidone was dissolved at a temperature of 150 ° C. in a proportion of 77% by weight to obtain a coating solution. A support membrane was obtained using the same support membrane solution as in Example 1. This support film is supplied into the coating nozzle, and on the other hand, the obtained coating solution is supplied and pulled out while coating the support film, and then combined through a process of coagulating in a 2% NMP aqueous solution at 35 ° C. and a solvent removal process. A hollow fiber membrane was obtained.
得られた複合中空糸膜の構造形態は、外径が１４１０μｍ、内径が７５６μｍ、コート層の平均厚さが６６μｍ、コート層の最外表面の平均孔径が０．０２μｍ、三次元網目構造の平均孔径が０．４μｍ、支持膜の球状（構造）の平均直径が２．７μｍであった。純水透過性能が０．２０ｍ３／ｍ２／ｈｒ、ウイルス除去性能は、ウイルス除去率は、初期値で＞７ｌｏｇ、総ろ過水量が約０．１３ｍ３／ｍ２に達した時点の値で＞７ｌｏｇのウイルスが洩れない除去性能を示した。糸物性値は、破断強度が１４．６Ｐａ、破断伸度４０％であり、琵琶湖水におけるろ過抵抗上昇度は、０．４４×１０１２／ｍ２を示す、耐汚れ性に優れた複合中空糸膜であった。なお評価結果を表１にまとめた。 The structure of the obtained composite hollow fiber membrane has an outer diameter of 1410 μm, an inner diameter of 756 μm, an average thickness of the coat layer of 66 μm, an average pore diameter of the outermost surface of the coat layer of 0.02 μm, and an average of a three-dimensional network structure The pore diameter was 0.4 μm, and the average diameter of the spherical shape (structure) of the support membrane was 2.7 μm. Pure water permeation performance is 0.20 m 3 / m 2 / hr, virus removal performance is the value when virus removal rate is> 7 log at the initial value, and the total filtered water volume reaches about 0.13 m 3 / m 2. The removal performance was such that> 7 log virus did not leak. Yarn physical property values are a break strength of 14.6 Pa, a break elongation of 40%, and an increase in filtration resistance in Lake Biwa water of 0.44 × 10 12 / m 2. It was a membrane. The evaluation results are summarized in Table 1.
＜実施例４＞
実施例１と同様の支持膜溶液を用いて、製膜紡糸した支持膜をコートノズル内に導入し、一方で溶融粘度測定値が３９００Ｐａ・ｓのフッ化ビニリデンホモポリマー（アルケマ社製，ｋｙｎａｒ（登録商標）ＨＳＶ９００，カタログ記載の溶融粘度３３００〜５５００Ｐａ・ｓ）１６重量％、セルロースアセテート（イーストマンケミカル社、ＣＡ４３５−７５Ｓ：三酢酸セルロース、ＣＡ３９８−３：二酢酸セルロース）４．５重量％、Ｎ−メチル−２−ピロリドンを７９．５重量％の割合として温度１５０℃で溶解したコート溶液をコートノズルに供給して、支持膜をコーティングしながら引き出し、その後３５℃の水中で凝固させる工程、脱溶媒工程を経て複合中空糸膜を得た。
<Example 4>
Using the same support membrane solution as in Example 1, a film-spun support membrane was introduced into a coat nozzle, while a vinylidene fluoride homopolymer having a melt viscosity measurement value of 3900 Pa · s (manufactured by Arkema, kynar ( (Registered trademark) HSV900, melt viscosity 3300-5500 Pa · s described in the catalog 16% by weight, cellulose acetate (Eastman Chemical Co., CA435-75S: cellulose triacetate, CA398-3: cellulose diacetate) 4.5% by weight, Supplying a coating solution in which N-methyl-2-pyrrolidone is dissolved at a temperature of 150 ° C. at a ratio of 79.5% by weight to the coating nozzle, drawing it out while coating the support film, and then coagulating in water at 35 ° C .; A composite hollow fiber membrane was obtained through a solvent removal step.
得られた複合中空糸膜の構造形態は、外径が１４０２μｍ、内径が７５５μｍ、コート層の平均厚さが７０μｍ、コート層の最外表面の平均孔径が０．０３μｍ、コート層の三次元網目構造の平均孔径が０．４μｍ、支持膜の球状（構造）の平均直径が２．６μｍであった。純水透過性能が０．２４ｍ３／ｍ２／ｈｒ、ウイルス除去性能は、初期値で＞７ｌｏｇ、総ろ過水量が約０．１３ｍ３／ｍ２に達した時点の値で＞７ｌｏｇのウイルスが洩れない除去性能を示した。糸物性値は、破断強度が１３．０ＭＰａ、破断伸度４３％であり、琵琶湖水におけるろ過抵抗上昇度は、０．８８×１０１２／ｍ２を示した。なお評価結果を表１にまとめた。 The structure of the obtained composite hollow fiber membrane has an outer diameter of 1402 μm, an inner diameter of 755 μm, an average thickness of the coat layer of 70 μm, an average pore diameter of the outermost surface of the coat layer of 0.03 μm, and a three-dimensional mesh of the coat layer The average pore diameter of the structure was 0.4 μm, and the average diameter of the spherical shape (structure) of the support membrane was 2.6 μm. Pure water permeation performance is 0.24 m 3 / m 2 / hr, virus removal performance is> 7 log at the initial value, and> 7 log virus at the time when the total filtrate reaches about 0.13 m 3 / m 2. The removal performance which does not leak is shown. The yarn physical properties were a breaking strength of 13.0 MPa and a breaking elongation of 43%, and an increase in filtration resistance in Lake Biwa water was 0.88 × 10 12 / m 2 . The evaluation results are summarized in Table 1.
＜実施例５＞
重量平均分子量４２万のフッ化ビニリデンホモポリマー３２重量％および四フッ化エチレンとフッ化ビニリデンの共重合体（アルケマ社製、Ｋｙｎａｒ（登録商標）７２０１）６重量％にγ−ブチロラクトン６２重量％を１５０℃で溶解して支持膜用溶液を得た。また溶融粘度測定値が４７００Ｐａ・ｓのフッ化ビニリデンホモポリマー１４．５重量％、セルロースアセテート（イーストマンケミカル社、ＣＡ４３５−７５５：三酢酸セルロース、ＣＡ３９８−３：二酢酸セルロース）４重量％、Ｎ−メチル−２−ピロリドンを８１．５重量％の割合として温度１５０℃で溶解し、コート溶液を得た。この支持膜用溶液を二重管状紡糸ノズルの外側スリットから、γ−ブチロラクトン８８重量％水溶液を二重管状紡糸ノズルの中心パイプから共に同心円状に押し出し、凝固温度が１０℃のγ−ブチロラクトン８８重量％水溶液中で固化させた後、１．５倍の延伸工程、脱溶媒工程、乾燥工程を経て支持膜を得た。この支持膜をコートノズル内に導入し、一方で得られたコート溶液をコートノズルに供給して支持膜をコーティングしながら引き出し、その後２５℃の水中で凝固させる工程、脱溶媒工程を経て中空糸状の複合膜を得た。
<Example 5>
32% by weight of a vinylidene fluoride homopolymer having a weight average molecular weight of 420,000 and 6% by weight of a copolymer of ethylene tetrafluoride and vinylidene fluoride (Kynar (registered trademark) 7201 manufactured by Arkema Co., Ltd.) are added by 62% by weight of γ-butyrolactone. It melt | dissolved at 150 degreeC and the solution for support membranes was obtained. Further, a vinylidene fluoride homopolymer having a melt viscosity measured value of 4700 Pa · s is 14.5% by weight, cellulose acetate (Eastman Chemical Co., CA435-755: cellulose triacetate, CA398-3: cellulose diacetate) 4% by weight, N -Methyl-2-pyrrolidone was dissolved at a temperature of 150 ° C. at a ratio of 81.5% by weight to obtain a coating solution. The support membrane solution was extruded from the outer slit of the double tubular spinning nozzle, and an aqueous solution of 88% by weight of γ-butyrolactone was extruded concentrically from the center pipe of the double tubular spinning nozzle, and the solidification temperature was 10 ° C. and 88 weight of γ-butyrolactone. After solidifying in an aqueous solution, a support film was obtained through a 1.5-fold stretching process, a solvent removal process, and a drying process. This support membrane is introduced into the coat nozzle, while the obtained coating solution is supplied to the coat nozzle and pulled out while coating the support membrane, and then solidified in water at 25 ° C., followed by a solvent removal step to form a hollow fiber A composite membrane was obtained.
得られた複合中空糸膜の構造形態は、外径が１３９０μｍ、内径が７４０μｍ、コート層の平均厚さが４８μｍで一部にマクロボイドを内包していた。コート層の最外表面の平均孔径が０．０２μｍ、三次元網目構造の平均孔径が０．４μｍ、支持膜の球状（構造）の平均直径が２．５μｍであって、純水透過性能が０．３６ｍ３／ｍ２／ｈｒ、ウイルス除去性能は、初期値で＞７ｌｏｇ、総ろ過水量が約０．１３ｍ３／ｍ２に達した時点の値で６．６ｌｏｇの高いウイルス除去性能を示した。糸物性値は、破断強度が９．２ＭＰａ、破断伸度４３％であり、琵琶湖水におけるろ過抵抗上昇度は、１．３×１０１２／ｍ２を示した。なお評価結果を表１にまとめた。 The structure of the obtained composite hollow fiber membrane had an outer diameter of 1390 μm, an inner diameter of 740 μm, an average thickness of the coating layer of 48 μm, and partly contained macrovoids. The average pore diameter of the outermost surface of the coating layer is 0.02 μm, the average pore diameter of the three-dimensional network structure is 0.4 μm, the average diameter of the spherical shape (structure) of the support membrane is 2.5 μm, and the pure water permeation performance is 0 .36 m 3 / m 2 / hr, virus removal performance was> 7 log at the initial value, and high virus removal performance of 6.6 log at the time when the total amount of filtered water reached about 0.13 m 3 / m 2 . The yarn physical properties were as follows: the breaking strength was 9.2 MPa, the breaking elongation was 43%, and the increase in filtration resistance in Lake Biwa water was 1.3 × 10 12 / m 2 . The evaluation results are summarized in Table 1.
＜比較例１＞
実施例１と同様の支持膜溶液を用いて、製膜紡糸した支持膜をコートノズル内に導入し、一方で溶融粘度測定値が２７００Ｐａ・ｓのフッ化ビニリデンホモポリマー（アルケマ社製，ｋｙｎａｒ（登録商標）７６０、カタログ記載の溶融粘度２３００〜２９００Ｐａ・ｓ）１６重量％、セルロースアセテート（イーストマンケミカル社、ＣＡ４３５−７５Ｓ：三酢酸セルロース、ＣＡ３９８−３：二酢酸セルロース）４重量％、Ｎ−メチル−２−ピロリドンを８２重量％の割合として温度１４０℃で溶解したコート溶液をコートノズルに供給して支持膜をコーティングしながら引き出し、その後３５℃の水中で凝固させる工程、脱溶媒工程を経て複合中空糸膜を得た。
<Comparative Example 1>
Using the same support membrane solution as in Example 1, a membrane-spun support membrane was introduced into a coat nozzle, while a vinylidene fluoride homopolymer having a melt viscosity measurement value of 2700 Pa · s (manufactured by Arkema, kynar ( Registered trademark) 760, melt viscosity 2300-2900 Pa · s) described in the catalog 16% by weight, cellulose acetate (Eastman Chemical Co., CA435-75S: cellulose triacetate, CA398-3: cellulose diacetate) 4% by weight, N- A coating solution in which methyl-2-pyrrolidone is dissolved at a temperature of 140 ° C. in a proportion of 82% by weight is supplied to the coating nozzle and pulled out while coating the support membrane, and then solidified in water at 35 ° C., followed by a solvent removal step. A composite hollow fiber membrane was obtained.
得られた複合中空糸膜の構造形態は、外径が１４２０μｍ、内径が７６０μｍ、コート層の平均厚さが５６μｍ、コート層の最外表面の平均孔径が０．０５μｍ、コート層の三次元網目構造の平均孔径が０．６μｍ、支持膜の球状（構造）の平均直径が２．６μｍであった。純水透過性能が０．４４ｍ３／ｍ２／ｈｒ、ウイルス除去性能は、初期値で４．２ｌｏｇの低い除去性能を示した。糸物性値は、破断強度が１０．２ＭＰａ、破断伸度３８％であり、琵琶湖水におけるろ過抵抗上昇度は、０．６８×１０１２／ｍ２を示した。なお評価結果を表１にまとめた。 The structure of the obtained composite hollow fiber membrane has an outer diameter of 1420 μm, an inner diameter of 760 μm, an average thickness of the coat layer of 56 μm, an average pore diameter of the outermost surface of the coat layer of 0.05 μm, and a three-dimensional network of the coat layer The average pore diameter of the structure was 0.6 μm, and the average diameter of the spherical shape (structure) of the support membrane was 2.6 μm. Pure water permeation performance was 0.44 m 3 / m 2 / hr, and virus removal performance showed a low removal performance of 4.2 log at the initial value. The yarn physical properties were 10.2 MPa at break strength and 38% at break elongation, and the increase in filtration resistance in Lake Biwa water was 0.68 × 10 12 / m 2 . The evaluation results are summarized in Table 1.
＜比較例２＞
実施例１と同様の支持膜溶液を用いて、製膜紡糸した支持膜をコートノズル内に導入し、一方で溶融粘度測定値が４７００Ｐａ・ｓのフッ化ビニリデンホモポリマー（アルケマ社製，ｋｙｎａｒ（登録商標）ＨＳＶ９００、カタログ記載の溶融粘度３３００〜５５００Ｐａ・ｓ）１２重量％、セルロースアセテート（イーストマンケミカル社、ＣＡ４３５−７５Ｓ：三酢酸セルロース、ＣＡ３９８−３：二酢酸セルロース）７．２重量％、Ｎ−メチル−２−ピロリドンを８０．８重量％の割合として温度１４０℃で溶解したコート溶液をコートノズルに供給して、支持膜をコーティングしながら引き出し、その後３５℃の水中で凝固させる工程、脱溶媒工程を経て複合中空糸膜を得た。
<Comparative example 2>
Using the same support membrane solution as in Example 1, a membrane-spun support membrane was introduced into a coat nozzle, while a vinylidene fluoride homopolymer having a melt viscosity measurement value of 4700 Pa · s (manufactured by Arkema, kynar ( (Registered trademark) HSV900, melt viscosity 3300-5500 Pa · s described in the catalog 12% by weight, cellulose acetate (Eastman Chemical Co., CA435-75S: cellulose triacetate, CA398-3: cellulose diacetate) 7.2% by weight, Supplying a coating solution in which N-methyl-2-pyrrolidone is dissolved at a temperature of 140 ° C. at a rate of 80.8% by weight to a coating nozzle, drawing out while coating the support film, and then coagulating in water at 35 ° C .; A composite hollow fiber membrane was obtained through a solvent removal step.
得られた複合中空糸膜の構造形態は、外径が１４０８μｍ、内径が７５２μｍ、コート層の平均厚さが４６μｍ、コート層の最外表面の平均孔径が０．０６μｍ、コート層の三次元網目構造の平均孔径が０．８μｍ、支持膜の球状（構造）の平均直径が２．６μｍであった。純水透過性能が０．２４ｍ３／ｍ２／ｈｒ、ウイルス除去性能は、初期値で３．２ｌｏｇの低い除去性能を示した。糸物性値は、破断強度が９．２ＭＰａ、破断伸度３８％であり、琵琶湖水におけるろ過抵抗上昇度は、０．５５×１０１２／ｍ２を示した。なお評価結果を表１にまとめた。 The structure of the obtained composite hollow fiber membrane has an outer diameter of 1408 μm, an inner diameter of 752 μm, an average thickness of the coat layer of 46 μm, an average pore diameter of the outermost surface of the coat layer of 0.06 μm, and a three-dimensional network of the coat layer The average pore diameter of the structure was 0.8 μm, and the average diameter of the spherical shape (structure) of the support membrane was 2.6 μm. Pure water permeation performance was 0.24 m 3 / m 2 / hr, and virus removal performance showed a low removal performance of 3.2 logs at the initial value. The yarn physical properties were as follows: the breaking strength was 9.2 MPa, the breaking elongation was 38%, and the increase in filtration resistance in Lake Biwa water was 0.55 × 10 12 / m 2 . The evaluation results are summarized in Table 1.
＜比較例３＞
実施例１と同様の支持膜溶液を用いて、製膜紡糸した支持膜をコートノズル内に導入し、一方で溶融粘度測定値が４７００Ｐａ・ｓのフッ化ビニリデンホモポリマー（アルケマ社製，ｋｙｎａｒ（登録商標）ＨＳＶ９００，カタログ記載の溶融粘度３３００〜５５００Ｐａ・ｓ）１８重量％、Ｎ−メチル−２−ピロリドンを８２重量％の割合として温度１５０℃で溶解したコート溶液をコートノズルに供給して支持膜をコーティングしながら引き出し、その後３５℃の水中で凝固させる工程、脱溶媒工程を経て複合中空糸膜を得た。
<Comparative Example 3>
Using the same support membrane solution as in Example 1, a membrane-spun support membrane was introduced into a coat nozzle, while a vinylidene fluoride homopolymer having a melt viscosity measurement value of 4700 Pa · s (manufactured by Arkema, kynar ( (Registered trademark) HSV900, melt viscosity 3300-5500 Pa · s described in catalog, 18 wt%, N-methyl-2-pyrrolidone dissolved at a temperature of 150 ° C. at a rate of 82 wt% is supplied to the coat nozzle for support The composite hollow fiber membrane was obtained through a step of coagulating in water at 35 ° C. and a desolvation step.
得られた複合中空糸膜の構造形態は、外径が１４３０μｍ、内径が７５６μｍ、コート層の平均厚さが８０μｍ、コート層の最外表面の平均孔径が０．０４μｍ、コート層の三次元網目構造の平均孔径が０．６μｍ、支持膜の球状（構造）の平均直径が２．６μｍであった。純水透過性能が０．２４ｍ３／ｍ２／ｈｒ、ウイルス除去性能は、初期値で４．２ｌｏｇの低い除去性能を示した。糸物性値は、破断強度が１４．２ＭＰａ、破断伸度６８％であり、琵琶湖水におけるろ過抵抗上昇度は、２．３×１０１２／ｍ２を示した。なお評価結果を表１にまとめた。 The structure of the obtained composite hollow fiber membrane has an outer diameter of 1430 μm, an inner diameter of 756 μm, an average thickness of the coat layer of 80 μm, an average pore diameter of the outermost surface of the coat layer of 0.04 μm, and a three-dimensional mesh of the coat layer The average pore diameter of the structure was 0.6 μm, and the average diameter of the spherical shape (structure) of the support membrane was 2.6 μm. Pure water permeation performance was 0.24 m 3 / m 2 / hr, and virus removal performance showed a low removal performance of 4.2 log at the initial value. The yarn physical properties were a breaking strength of 14.2 MPa and a breaking elongation of 68%, and an increase in filtration resistance in Lake Biwa water was 2.3 × 10 12 / m 2 . The evaluation results are summarized in Table 1.
本発明によれば簡便なコーティング方法で、支持膜上に高いウイルス除去性能、かつ耐ファウリング性を有するポリフッ化ビニリデン系樹脂の分離機能層を形成する複合膜を製造する方法を提供できる。これにより水処理用途に使用した場合、透過水の水質向上と長期再生使用が可能になる。 ADVANTAGE OF THE INVENTION According to this invention, the method of manufacturing the composite membrane which forms the isolation | separation functional layer of the polyvinylidene fluoride resin which has a high virus removal performance and fouling resistance on a support membrane with a simple coating method can be provided. Thereby, when it uses for a water treatment use, the water quality improvement of permeated water and long-term reproduction use are attained.
Claims (2)
該コート層の最外表面孔径が平均０．０１μｍ以上０．１μｍ以下であり、コート層内に平均孔径０．０１μｍ以上０．５μｍ以下、かつ厚さ１０μｍ以上１２０μｍ以下の三次元網目構造が形成されていることを特徴とする複合膜。 A support film, and a coating layer formed on the support film with a polyvinylidene fluoride resin containing 9 to 46% by weight of a cellulose ester and a melt viscosity of 3300 Pa · s or more,
The outermost surface pore diameter of the coat layer is 0.01 μm or more and 0.1 μm or less on average, and a three-dimensional network structure having an average pore diameter of 0.01 μm or more and 0.5 μm or less and a thickness of 10 μm or more and 120 μm or less is formed in the coat layer. A composite membrane characterized by being made.
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103990387A (en) * | 2013-02-15 | 2014-08-20 | 帕尔公司 | Composite including PTFE Membrane |
| JP2019083794A (en) * | 2017-11-10 | 2019-06-06 | 永嶋 良一 | Carrier production method and carrier |
| JP2022525882A (en) * | 2019-03-15 | 2022-05-20 | インテグリス・インコーポレーテッド | Composite hollow fibers and related methods and products |
| CN115245755A (en) * | 2021-04-25 | 2022-10-28 | 中国石油化工股份有限公司 | Internal pressure type hollow fiber ultrafiltration membrane and preparation method and application thereof |
| WO2024087772A1 (en) * | 2022-10-27 | 2024-05-02 | 杭州科百特过滤器材有限公司 | Virus-removing composite membrane and preparation process therefor |
| US11998878B2 (en) | 2020-03-12 | 2024-06-04 | Entegris, Inc. | Composite hollow fiber and related methods and products |
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2012
- 2012-02-24 JP JP2012038366A patent/JP2012187575A/en active Pending
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103990387A (en) * | 2013-02-15 | 2014-08-20 | 帕尔公司 | Composite including PTFE Membrane |
| JP2019083794A (en) * | 2017-11-10 | 2019-06-06 | 永嶋 良一 | Carrier production method and carrier |
| JP2022525882A (en) * | 2019-03-15 | 2022-05-20 | インテグリス・インコーポレーテッド | Composite hollow fibers and related methods and products |
| JP7384922B2 (en) | 2019-03-15 | 2023-11-21 | インテグリス・インコーポレーテッド | Composite hollow fibers and related methods and products |
| US11998878B2 (en) | 2020-03-12 | 2024-06-04 | Entegris, Inc. | Composite hollow fiber and related methods and products |
| CN115245755A (en) * | 2021-04-25 | 2022-10-28 | 中国石油化工股份有限公司 | Internal pressure type hollow fiber ultrafiltration membrane and preparation method and application thereof |
| CN115245755B (en) * | 2021-04-25 | 2024-02-13 | 中国石油化工股份有限公司 | Internal pressure type hollow fiber ultrafiltration membrane and preparation method and application thereof |
| WO2024087772A1 (en) * | 2022-10-27 | 2024-05-02 | 杭州科百特过滤器材有限公司 | Virus-removing composite membrane and preparation process therefor |
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