JP2002301342A - Polyvinylidene fluoride porous separation membrane - Google Patents
Polyvinylidene fluoride porous separation membraneInfo
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- JP2002301342A JP2002301342A JP2001109430A JP2001109430A JP2002301342A JP 2002301342 A JP2002301342 A JP 2002301342A JP 2001109430 A JP2001109430 A JP 2001109430A JP 2001109430 A JP2001109430 A JP 2001109430A JP 2002301342 A JP2002301342 A JP 2002301342A
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- membrane
- back pressure
- polyvinylidene fluoride
- porous
- separation membrane
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Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、ポリフッ化ビニリ
デン多孔質分離膜に関するものであり、食品工業におけ
るアルコール飲料や果汁飲料等の除菌、除濁、除蛋白
質、半導体製造工業における超純水の製造、医薬品工業
における無菌水の製造、各種工業排水、ビル等の建築物
排水、下水の除濁、河川水、かん水、海水の逆浸透法に
よる脱塩の前処理などに用いられ、菌体や微粒子及び高
分子物質を効率良く分離・除去し、且つ機械的強度に優
れ、逆圧洗浄が可能であり、高い逆圧繰り返し疲労耐性
を持つ精密渡過または限外濾過用の多孔質分離膜に関す
るものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyvinylidene fluoride porous separation membrane, which removes bacteria, turbidity, and protein in alcoholic beverages and fruit juice beverages in the food industry, and ultrapure water in the semiconductor manufacturing industry. It is used for manufacturing, aseptic water production in the pharmaceutical industry, various industrial wastewater, drainage of buildings and other buildings, turbidity of sewage, pretreatment of desalination by reverse osmosis of river water, brackish water, seawater, etc. It relates to a porous separation membrane for precision transit or ultrafiltration that efficiently separates and removes fine particles and polymer substances, has excellent mechanical strength, is capable of back pressure washing, and has high back pressure repeated fatigue resistance. Things.
【０００２】[0002]
【従来の技術】従来、上記諸工業分野で用いられている
多孔質分離膜としては、セルロースエステル、ポリアミ
ド、ポリイミド、ポリスルホン、ポリフルオロカーボ
ン、ポリフッ化ビニリデン、ポリエチレン、ポリプロピ
レン、ポリビニルアルコール、ポリアクリロニトリル等
の高分子を素材とするものなどが挙げられる（例えば、
特開昭５８−１４６４０８号公報、特開昭６１−２２２
５０５号公報、特開昭５６−１５４０５１号公報、特開
昭５７−６６１１４号公報、特開昭５２−１５６２７号
公報、特開昭５８−４５２３９号公報、特開平０６−３
３６１５７号公報）。これらのうち、ポリスルホン、ポ
リフッ化ビニリデン樹脂、ポリエーテルスルホン等は、
機械的強度に優れ、且つ耐熱性、耐薬品性に優れた膜素
材であることが知られている。2. Description of the Related Art Conventionally, porous separation membranes used in the above various industrial fields include cellulose ester, polyamide, polyimide, polysulfone, polyfluorocarbon, polyvinylidene fluoride, polyethylene, polypropylene, polyvinyl alcohol, polyacrylonitrile and the like. And those using a polymer as a material (for example,
JP-A-58-146408, JP-A-61-222
505, JP-A-56-154051, JP-A-57-66114, JP-A-52-15627, JP-A-58-45239, JP-A-06-3
No. 36157). Among these, polysulfone, polyvinylidene fluoride resin, polyether sulfone, etc.
It is known that the film material is excellent in mechanical strength, and excellent in heat resistance and chemical resistance.
【０００３】このような多孔質分離膜では、使用中に膜
の表面及び内部にろ過した分離物が付着し、徐々に性能
が低下する。そのため、定期的な膜の洗浄が必要になる
が、その方法としては、大きく分けて薬品洗浄と物理洗
浄に分けられる。前者としてはシュウ酸溶液、水酸化ナ
トリウム溶液、次亜塩素酸ナトリウム溶液等の薬品に浸
潰する方法、後者としては、膜のろ過側の反対方向（支
持体側）からエアバブルや水などで圧力をかける事によ
り、付着物を物理的に洗い流す逆圧洗浄と言われる方法
が一般的である。これらの洗浄では、多孔質分離膜に対
し、大きな負荷がかかる。即ち、薬品洗浄では薬品に対
する高い耐性が必要となり、物理洗浄では、膜に対して
高い背圧耐性が必要となる。[0003] In such a porous separation membrane, during filtration, the separated product adheres to the surface and inside of the membrane, and the performance gradually decreases. Therefore, it is necessary to periodically clean the film. The method is roughly divided into chemical cleaning and physical cleaning. The former is a method of immersion in chemicals such as oxalic acid solution, sodium hydroxide solution, sodium hypochlorite solution, etc., and the latter is a method in which pressure is applied by air bubbles or water from the opposite side of the membrane filtration side (support side). Generally, a method called back-pressure cleaning in which the adhered substance is physically washed away by applying the liquid is generally used. In these washings, a large load is applied to the porous separation membrane. That is, chemical cleaning requires high resistance to chemicals, and physical cleaning requires high back pressure resistance to the membrane.
【０００４】このような物理洗浄と薬品洗浄の両方が可
能な膜としては、特開平９−３１３９０５号公報に、表
面から厚み方向に連続的に孔径が拡大する非対称構造を
有し、多孔性補強シートに投錨状態で接合したポリスル
ホン多孔質分離膜が開示されている。Japanese Patent Application Laid-Open No. Hei 9-313905 discloses a membrane capable of performing both physical cleaning and chemical cleaning, which has an asymmetric structure in which the pore diameter continuously increases from the surface in the thickness direction, and has a porous reinforcement. A polysulfone porous separation membrane bonded to a sheet in an anchor state is disclosed.
【０００５】[0005]
【発明が解決しようとする課題】しかしながら、この分
離膜は伸びの小さいポリスルホン樹脂を膜素材とする不
織布補強膜であるため、逆圧洗浄を繰り返すと膜全体の
伸縮にポリスルホン膜層が追従できず、疲労による劣化
が生じることが判明した。従って、逆圧洗浄を繰り返す
ような使用条件下では、必ずしも実用的に十分な分離膜
とは言い難い。However, since this separation membrane is a nonwoven fabric reinforced membrane made of a polysulfone resin having a small elongation, the polysulfone membrane layer cannot follow the expansion and contraction of the entire membrane when repeated backwashing is repeated. It has been found that deterioration due to fatigue occurs. Therefore, it is not always possible to say that the separation membrane is practically sufficient under use conditions in which the back pressure washing is repeated.
【０００６】一方、多孔質分離膜の機械的特性は、膜素
材のみならず、膜の微細構造やマクロボイド（指状空洞
など）の有無、不織布等への製膜原液の含浸量などに影
響されるため、膜素材の機械的特性がそのまま多孔質分
離膜の特性として発現されにくい面がある。[0006] On the other hand, the mechanical properties of the porous separation membrane affect not only the membrane material, but also the microstructure of the membrane, the presence or absence of macrovoids (such as finger-like cavities), and the amount of a nonwoven fabric or the like impregnated with a stock solution. Therefore, the mechanical properties of the membrane material are not easily expressed as the properties of the porous separation membrane.
【０００７】そこで、本発明の目的は、前記従来の問題
を解決すべく、高い瞬間背圧耐性、繰り返し背圧疲労へ
の耐性を有しながら、菌体や微粒子及び高分子物質を効
率的に分離・除去し、従来よりも逆圧洗浄圧力を高める
事が可能で、膜劣化が少なく、膜寿命の長いポリフッ化
ビニリデン多孔質分離膜を提供することにある。[0007] Therefore, an object of the present invention is to solve the above-mentioned conventional problems by efficiently removing bacterial cells, fine particles and polymer substances while having high instantaneous back pressure resistance and resistance to repeated back pressure fatigue. It is an object of the present invention to provide a polyvinylidene fluoride porous separation membrane which can be separated and removed, can increase the back pressure washing pressure as compared with the conventional one, has little membrane deterioration, and has a long membrane life.
【０００８】[0008]
【課題を解決するための手段】本発明者らは、上記目的
を達成すべく膜素材や膜構造等について鋭意研究したと
ころ、ポリフッ化ビニリデンを膜素材とすることで、背
圧疲労による劣化に対し膜全体の伸びに追従することが
でき、また特定の多孔性補強シートを使用し図１のよう
な膜との接合状態とすることによって、初期の背圧強度
と繰り返し背圧耐性とが高く、膜寿命の長い多孔質分離
膜が実現できることを見出し、本発明を完成するに至っ
た。Means for Solving the Problems The present inventors have conducted intensive studies on the film material and the film structure in order to achieve the above-mentioned object, and found that polyvinylidene fluoride is used as the film material to prevent deterioration due to back pressure fatigue. On the other hand, it is possible to follow the elongation of the whole membrane, and by using a specific porous reinforcing sheet to join the membrane as shown in FIG. 1, the initial back pressure strength and the repeated back pressure resistance are high. The present inventors have found that a porous separation membrane having a long membrane life can be realized, and have completed the present invention.
【０００９】即ち、本発明のポリフッ化ビニリデン多孔
質分離膜は、分離機能を有するポリフッ化ビニリデン多
孔質膜が多孔性補強シートの孔内に部分的に投錨されて
支持された分離膜であって、有効直径２３ｍｍの円孔型
ホルダーに保持して背圧０ＭＰａと背圧０．２ＭＰａと
を繰り返す背圧疲労テストでの耐久繰り返し回数が５万
回以上であることを特徴とする。ここで、背圧疲労テス
トの詳細な条件は、実施例に示すとおりである。That is, the polyvinylidene fluoride porous separation membrane of the present invention is a separation membrane in which a polyvinylidene fluoride porous membrane having a separation function is supported by being partially anchored in the pores of the porous reinforcing sheet. The number of durability repetitions in a back pressure fatigue test in which a back pressure of 0 MPa and a back pressure of 0.2 MPa are repeated while being held in a circular hole holder having an effective diameter of 23 mm is 50,000 or more. Here, the detailed conditions of the back pressure fatigue test are as shown in Examples.
【００１０】上記において、前記多孔性補強シートの厚
みが０．０８〜０．２ｍｍであり、かつ密度が０．５〜
０．８ｇ／ｃｍ3 であることが好ましい。[0010] In the above, the thickness of the porous reinforcing sheet is 0.08 to 0.2 mm and the density is 0.5 to 0.2 mm.
It is preferably 0.8 g / cm 3 .
【００１１】[0011]
【発明の実施の形態】以下、図面を用いて本発明の実施
の形態を説明する。図１は本発明のポリフッ化ビニリデ
ン多孔質分離膜を説明するための模式図である。Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram for explaining a polyvinylidene fluoride porous separation membrane of the present invention.
【００１２】本発明の多孔質分離膜は、図１に示すよう
に、多孔性補強シート２１の表面に分離機能を有するポ
リフッ化ビニリデン多孔質膜２２の表層部が形成され、
この多孔質膜２２を構成する樹脂成分の一部が、多孔性
補強シート２１に投錨状態で接合し補強されている。但
し、本発明における多孔性補強シート２１としては、不
織布等が好適に用いられるため、実際の構造は、不織布
を構成する繊維間に樹脂成分が部分的に投錨（アンカー
結合）された更に複雑な構造となる。従って、本発明に
おける「投錨されて支持された」状態とは、図１に示す
ように多孔性補強シート２１の裏面付近における投錨に
限らず、多孔性補強シート２１の内部のみで投錨されて
いる構造を含むものである。In the porous separation membrane of the present invention, as shown in FIG. 1, a surface portion of a polyvinylidene fluoride porous membrane 22 having a separation function is formed on the surface of a porous reinforcing sheet 21.
Part of the resin component constituting the porous film 22 is joined to the porous reinforcing sheet 21 in an anchored state and reinforced. However, since a nonwoven fabric or the like is suitably used as the porous reinforcing sheet 21 in the present invention, the actual structure is a more complicated structure in which the resin component is partially anchored (anchor-bonded) between the fibers constituting the nonwoven fabric. Structure. Therefore, the “anchored and supported” state in the present invention is not limited to the anchor near the back surface of the porous reinforcing sheet 21 as shown in FIG. 1, but is anchored only inside the porous reinforcing sheet 21. Including the structure.
【００１３】このポリフッ化ビニリデン多孔質分離膜２
０は、最小孔径層が膜表面に存在し、その平均孔径が通
常の精密濾過膜より１オーダー小さい０．０１〜０．０
８μｍの範囲であることが好ましい。このように限外濾
過膜に近い表面孔径を有することで、菌体や微粒子をほ
ぼ完全に膜表面で阻止することが可能となる。This polyvinylidene fluoride porous separation membrane 2
0 means that the minimum pore size layer is present on the membrane surface, and the average pore size is 0.01 to 0.0, which is one order smaller than that of a normal microfiltration membrane
It is preferably in the range of 8 μm. By having a surface pore size close to the ultrafiltration membrane in this way, it is possible to almost completely block bacterial cells and fine particles on the membrane surface.
【００１４】また、膜表面が擦過等で傷付いた場合で
も、微粒子の漏洩をきたすことのないように、膜孔径が
表面から厚み方向に連続的且つ緩やかに拡大し、膜の中
間部であっても微粒子を十分捕捉しうる程度の孔径とす
ることが好ましい。具体的には、膜表面から１μｍの位
置における断面写真での平均孔径が０．０８〜０．２μ
ｍ程度が好ましい。Further, even when the membrane surface is scratched or the like is scratched, the membrane pore diameter is continuously and gently enlarged in the thickness direction from the surface so as not to cause leakage of fine particles. Even so, it is preferable that the pore diameter is such that the fine particles can be sufficiently captured. Specifically, the average pore diameter in a cross-sectional photograph at a position 1 μm from the membrane surface is 0.08 to 0.2 μm.
m is preferable.
【００１５】また、ポリフッ化ビニリデン多孔質膜の表
層部の厚み（多孔性補強シート表面から膜表面までの厚
み）は、乾燥時の平均値で５０〜９０μｍが好ましい。
９０μｍより大きいと、濾過抵抗が大きくなることで透
過性能が低下したり、背圧疲労テストでの耐久繰り返し
回数が低下する傾向が見られ、また、５０μｍより小さ
いと、表層部の強度の低下により、背圧疲労テストでの
耐久繰り返し回数が低下する傾向がある。The thickness of the surface layer of the porous polyvinylidene fluoride membrane (the thickness from the surface of the porous reinforcing sheet to the surface of the membrane) is preferably 50 to 90 μm as an average value when dried.
If it is larger than 90 μm, permeation performance may be reduced due to increased filtration resistance, and the number of endurance repetitions in the back pressure fatigue test may be reduced. If it is smaller than 50 μm, the strength of the surface layer may be reduced. , The number of endurance repetitions in the back pressure fatigue test tends to decrease.
【００１６】本発明に用いられる多孔性補強シートとし
ては、ポリエステル、ポリプロピレン、ポリエチレン、
ポリアミド等を素材とする織布、不織布、メッシュ状ネ
ット、発泡焼結シート等が挙げられるが、後述する製膜
性及びコスト面から不織布が好適に用いられる。The porous reinforcing sheet used in the present invention includes polyester, polypropylene, polyethylene,
A woven fabric, a nonwoven fabric, a mesh net, a foam sintered sheet made of polyamide or the like may be used, but a nonwoven fabric is preferably used from the viewpoint of film forming properties and cost described later.
【００１７】本発明に用いられる多孔性補強シートとし
ては、厚みが０．０８〜０．２ｍｍであって、且つ密度
が０．５〜０．８ｇ／ｃｍ3 であることが好ましい。厚
みが０．０８ｍｍより薄いか又は密度が０．５ｇ／ｃｍ
3 より小さい場合には、補強シートとしての強度が得ら
れず、０．３ＭＰａ以上の背圧強度を維持することが困
難となる傾向がある。一方、厚みが０．２ｍｍより厚い
か又は密度が０．８ｇ／ｃｍ3 より大きい場合には．補
強膜の濾過抵抗が大きくなったり、多孔性補強シートへ
の膜の投錨効果が小さくなるため、膜と多孔性補強シー
トとの界面で剥離が起こりやすくなる傾向がある。The porous reinforcing sheet used in the present invention preferably has a thickness of 0.08 to 0.2 mm and a density of 0.5 to 0.8 g / cm 3 . Thickness is less than 0.08mm or density is 0.5g / cm
When it is smaller than 3 , strength as a reinforcing sheet cannot be obtained, and it tends to be difficult to maintain a back pressure strength of 0.3 MPa or more. On the other hand, if the thickness is greater than 0.2 mm or the density is greater than 0.8 g / cm 3 . Since the filtration resistance of the reinforcing membrane increases and the anchoring effect of the membrane on the porous reinforcing sheet decreases, separation tends to occur at the interface between the membrane and the porous reinforcing sheet.
【００１８】次に、本発明のポリフッ化ビニリデン多孔
質分離膜の製造方法について以下に述べる。ポリフッ化
ビニリデンに溶媒、非溶媒、及び膨潤剤を加えて加熱溶
解し、均一な製膜溶液を調製する。本発明に用いられる
ポリフッ化ビニリデン系樹脂は、下記式（化１）に示す
ように分子構造内の少なくとも１つに（−ＣＨ2 −ＣＦ
2 −）単位を有するものであれば特に限定されない。例
えば式（化１）を繰り返し単位として含む共重合体やブ
レンド体でもよい。Next, a method for producing the polyvinylidene fluoride porous separation membrane of the present invention will be described below. A solvent, a non-solvent, and a swelling agent are added to polyvinylidene fluoride and heated and dissolved to prepare a uniform film forming solution. The polyvinylidene fluoride resin used in the present invention has at least one (—CH 2 —CF) in the molecular structure as shown in the following formula (Formula 1).
It is not particularly limited as long as it has 2− ) units. For example, a copolymer or a blend containing the formula (Formula 1) as a repeating unit may be used.
【００１９】[0019]
【化１】（−ＣＨ2 −ＣＦ2 −）n 上記ポリフッ化ビニリデンの溶媒としては、Ｎ−メチル
−２−ピロリドン、ジメチルホルムアミド、ジメチルア
セトアミド、などが好ましく用いられる。また、非溶媒
としては、ジエチレングリコール、ポリエチレングリコ
ール、グリセリン等の脂肪族多価アルコール、メタノー
ル、エタノール、インプロピルアルコール等の低級脂肪
族アルコール、メチルエチルケトン等の低級脂肪族ケト
ン等が好ましく用いられる。Embedded image (—CH 2 —CF 2 —) n As the solvent for the polyvinylidene fluoride, N-methyl-2-pyrrolidone, dimethylformamide, dimethylacetamide, and the like are preferably used. As the non-solvent, aliphatic polyhydric alcohols such as diethylene glycol, polyethylene glycol and glycerin, lower aliphatic alcohols such as methanol, ethanol and propyl alcohol, and lower aliphatic ketones such as methyl ethyl ketone are preferably used.
【００２０】溶媒と非溶媒の混合溶媒中の非溶媒の含有
量は、得られる混合溶媒が均一である限り特に制限され
ないが、通常、５〜５０重量％、好ましくは２０〜４５
重量％である。The content of the non-solvent in the mixed solvent of the solvent and the non-solvent is not particularly limited as long as the obtained mixed solvent is uniform, but is usually 5 to 50% by weight, preferably 20 to 45% by weight.
% By weight.
【００２１】また、多孔質構造の形成を促進または制御
するために用いられる膨潤剤としては、塩化リチウム、
塩化ナトリウム、硝酸リチウム等の金属塩、ポリエチレ
ングリコール、ポリビニルアルコール、ポリビニルピロ
リドン、ポリアクリル酸等の水溶性高分子又はその金属
塩、ホルムアミド等が用いられる。混合溶媒中の膨潤剤
の含有量は、製膜溶液が均一である限り特に制限されな
いが、通常、１〜５０重量％である。The swelling agent used to promote or control the formation of the porous structure includes lithium chloride,
Metal salts such as sodium chloride and lithium nitrate, water-soluble polymers such as polyethylene glycol, polyvinyl alcohol, polyvinylpyrrolidone, and polyacrylic acid, and metal salts thereof, formamide, and the like are used. The content of the swelling agent in the mixed solvent is not particularly limited as long as the film forming solution is uniform, but is usually 1 to 50% by weight.
【００２２】本発明では、主に膨潤剤の種類や含有量に
よって、指状空洞の存在する膜構造（フィンガーボイド
構造）又は指状空洞の存在しない膜構造（スポンジ構
造）の何れの膜構造とすることもできるが、本発明にお
ける膜構造は両者の何れでもよい。但し、背圧疲労テス
トでの耐久繰り返し回数を向上させる上で、フィンガー
ボイド構造が好ましい。フィンガーボイド構造によっ
て、正圧、背圧の衝撃を吸収、緩和する働きがあると考
えられる。In the present invention, depending on the type and content of the swelling agent, the film structure may be either a film structure having finger-like cavities (finger void structure) or a film structure having no finger-like cavities (sponge structure). However, the film structure in the present invention may be either of them. However, a finger void structure is preferable in order to improve the number of endurance repetitions in the back pressure fatigue test. It is considered that the finger void structure has a function of absorbing and reducing the impact of positive pressure and back pressure.
【００２３】製膜溶液中のポリフッ化ビニリデンの濃度
は、通常１０〜３０重量％が好ましい。３０重量％を越
えるときは、得られる多孔質分離膜の透水性が実用性に
乏しく、一方、１０重量％より少ないときは、得られる
多孔質分離膜の機械的強度が乏しく、充分な背圧強度が
得られない傾向がある。The concentration of polyvinylidene fluoride in the film forming solution is usually preferably from 10 to 30% by weight. When the amount exceeds 30% by weight, the water permeability of the obtained porous separation membrane is poor in practicality. On the other hand, when the amount is less than 10% by weight, the mechanical strength of the obtained porous separation membrane is poor and sufficient back pressure is obtained. There is a tendency that strength cannot be obtained.
【００２４】次に、上記製膜溶液を図２に示すような連
続製膜装置により多孔性補強シートなどの支持体上に製
膜する。即ち、繰出し機１から多孔性補強シート２を繰
り出し、その表面に製膜溶液を塗布する。塗布方法は、
ナイフコーターやバーコーターのようなギャップコータ
ーにより、製膜溶液を多孔性補強シート上に塗布する。
本実施形態ではバーコーター４を使用し、コーターロー
ルとバッキングロールの間に製膜溶液３を溜め、多孔性
補強シート２上に塗布と同時に多孔性補強シート内部に
充分含浸させた後、高湿度雰囲気を通過させる間に塗布
した液膜５の表面より、雰囲気中の水分を吸収させ、液
膜５の表面層にミクロ相分離を起こさせる。６が相分離
ゾーンである。しかる後、凝固水槽７に浸潰し、液膜全
体を相分離・凝固させ、水洗槽９で溶媒を洗浄除去する
ことにより、本発明のポリフッ化ビニリデン多孔質分離
膜８を得、巻取機１０で巻き取る。Next, the above film forming solution is formed on a support such as a porous reinforcing sheet by a continuous film forming apparatus as shown in FIG. That is, the porous reinforcing sheet 2 is fed from the feeder 1, and a film forming solution is applied to the surface thereof. The application method is
The film forming solution is applied on the porous reinforcing sheet by a gap coater such as a knife coater or a bar coater.
In this embodiment, the bar coater 4 is used, the film forming solution 3 is stored between the coater roll and the backing roll, and is applied onto the porous reinforcing sheet 2 and simultaneously sufficiently impregnated into the porous reinforcing sheet. Moisture in the atmosphere is absorbed from the surface of the liquid film 5 applied during the passage of the atmosphere to cause microphase separation on the surface layer of the liquid film 5. 6 is a phase separation zone. Thereafter, the membrane is immersed in a coagulation water tank 7, the entire liquid film is phase-separated and coagulated, and the solvent is washed and removed in a water washing tank 9 to obtain a polyvinylidene fluoride porous separation membrane 8 of the present invention. Take up with.
【００２５】この製膜法はいわゆるドライウェット法の
一種であるが、液膜表面のミクロ相分離は、液膜表面か
らの溶媒の蒸発による相分離よりは、むしろ雰囲気中か
らの吸湿による相分離のほうが支配的であり、雰囲気湿
度及び吸湿時間の制御が重要である。製膜溶液の特性に
もよるが、通常、ミクロ相分離を起こさせる雰囲気は、
温度２０〜４０℃、相対湿度６５％以上、好ましくは７
５〜１００％、また、相分離時間、即ち吸湿時間は６〜
２４秒が好ましい。さらに、雰囲気内は実質的に無風状
態にすることが好ましい。This film-forming method is a kind of so-called dry-wet method, but the micro-phase separation on the surface of the liquid film is not the phase separation by evaporation of the solvent from the surface of the liquid film, but rather the phase separation by moisture absorption from the atmosphere. Is dominant, and control of the atmospheric humidity and the moisture absorption time is important. Depending on the properties of the film-forming solution, the atmosphere that causes microphase separation is usually
Temperature 20-40 ° C, relative humidity 65% or more, preferably 7
5 to 100%, and the phase separation time, that is, the moisture absorption time is 6 to
24 seconds is preferred. Further, it is preferable that the atmosphere be substantially in a windless state.
【００２６】以上のように、本発明のポリフッ化ビニリ
デン多孔質分離膜を製造するにはミクロ相分離の雰囲気
の制御が重要であるが、図２に示す製膜装置のコーター
下部の周囲をフィルム等で囲うことによって外気への水
分の蒸発を遮断し、さらに加湿器を用いて加湿すること
によって液膜表面からの吸湿とバランスがとられ、比較
的容易に６５％以上の高湿度に制御することができる。As described above, in order to manufacture the polyvinylidene fluoride porous separation membrane of the present invention, it is important to control the atmosphere of microphase separation. By enclosing it with the like, the evaporation of moisture to the outside air is blocked, and by humidifying using a humidifier, the moisture absorption from the liquid film surface is balanced, and the relative humidity can be relatively easily controlled to 65% or more. be able to.
【００２７】[0027]
【実施例】以下に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。EXAMPLES The present invention will be described below with reference to examples.
The present invention is not limited by these examples.
【００２８】（実施例１〜２）ポリフッ化ビニリデン
（呉羽化学工業社製、ＫＦＷ−＃１１００）１８重量
部、ジメチルアセトアミド６５重量部、ポリビニルピロ
リドン１０重量部、塩化リチウム４重量部、及びグリセ
リン３重量部を加熱溶解し、均一な製膜溶液を得た。ま
た、多孔性補強シートとして、厚み０．０９ｍｍ、密度
０．８ｇ／ｃｍ3 のポリエステル製不織布を用いた。(Examples 1 and 2) 18 parts by weight of polyvinylidene fluoride (KFW- # 1100 manufactured by Kureha Chemical Industry Co., Ltd.), 65 parts by weight of dimethylacetamide, 10 parts by weight of polyvinylpyrrolidone, 4 parts by weight of lithium chloride, and glycerin 3 The parts by weight were dissolved by heating to obtain a uniform film forming solution. In addition, a non-woven fabric made of polyester having a thickness of 0.09 mm and a density of 0.8 g / cm 3 was used as the porous reinforcing sheet.
【００２９】（実施例３）ポリフッ化ビニリデン（呉羽
化学工業社製、ＫＦＷ−＃１１００）２２重量部、ジメ
チルアセトアミド７５重量部、及びグリセリン３重量部
を加熱溶解し、均一な製膜溶液を得た。また、多孔性補
強シートとして、厚み０．０９ｍｍ、密度０．８ｇ／ｃ
ｍ3 のポリエステル製不織布を用いた。Example 3 22 parts by weight of polyvinylidene fluoride (KFW- # 1100 manufactured by Kureha Chemical Industry Co., Ltd.), 75 parts by weight of dimethylacetamide, and 3 parts by weight of glycerin were dissolved by heating to obtain a uniform film forming solution. Was. In addition, as a porous reinforcing sheet, the thickness is 0.09 mm, and the density is 0.8 g / c.
using a polyester nonwoven fabric of m 3.
【００３０】上記製膜溶液を図２に示す製膜装置を用い
てコーターギャップを０．１５ｍｍに調整したバーコー
ターにより上記不織布上に含浸塗布した。次いで、相対
湿度９５％、温度３０℃雰囲気中を製膜速度を変えるこ
とによって６秒間、１２秒間、２４秒間、それぞれ通過
させミクロ相分離を生じさせた後、３６℃の凝固水槽中
に浸潰して脱溶媒、凝固させ、しかる後水洗槽で残存溶
媒を洗浄除去することによりポリフッ化ビニリデン多孔
質分離膜を得た。The above film forming solution was impregnated and applied onto the nonwoven fabric by a bar coater with a coater gap adjusted to 0.15 mm using a film forming apparatus shown in FIG. Then, the film was passed through an atmosphere of a relative humidity of 95% and a temperature of 30 ° C. for 6 seconds, 12 seconds and 24 seconds by changing the film forming speed to cause microphase separation, and then immersed in a coagulation water bath at 36 ° C. Then, the solvent was removed and solidified, and then the remaining solvent was washed and removed in a water washing tank to obtain a polyvinylidene fluoride porous separation membrane.
【００３１】（試験例１）得られたそれぞれの膜につい
て、走査型電子顕微鏡により観察される膜表面の平均孔
径、透水量、平均分子量１０万のポリエチレンオキサイ
ドの阻止率、および背圧強度を測定し、表１に示した。
また、比較例１として同様の評価をポリスルホン膜（日
東電工（株）製，ＲＳ３０）で行った。(Test Example 1) With respect to each of the obtained membranes, the average pore diameter, water permeability, rejection of polyethylene oxide having an average molecular weight of 100,000, and back pressure strength of the membrane surface observed by a scanning electron microscope were measured. The results are shown in Table 1.
As Comparative Example 1, the same evaluation was performed using a polysulfone membrane (RS30, manufactured by Nitto Denko Corporation).
【００３２】ここで、ポリエチレンオキサイドの阻止率
は、濃度５００ｐｐｍのポリエチレンオキサイド溶液を
圧力０．２ＭＰａにて透過させ、原液及び透過液の濃度
から次式（数１）により求めた。Here, the rejection of polyethylene oxide was determined by permeating a polyethylene oxide solution having a concentration of 500 ppm at a pressure of 0.2 MPa from the concentrations of the undiluted solution and the permeated solution according to the following equation (Equation 1).
【数１】阻止率（％）＝［１−（透過液濃度／原液濃
度）］×１００ また、背圧強度は、直径４７ｍｍの膜を背圧強度ホルダ
ー（円孔の有効直径２３ｍｍ）にセットし、多孔性補強
シート上に製膜された多孔質分離膜の裏面、即ち不織布
側より水圧を徐々に加え、膜が不織布から剥離するか、
または膜と不織布が同時に破裂するときの圧力である。
結果を表１に示す。## EQU1 ## Inhibition ratio (%) = [1- (concentration of permeated liquid / concentration of undiluted solution)] × 100 The back pressure strength is set by setting a 47 mm diameter membrane in a back pressure strength holder (effective diameter of a circular hole: 23 mm). Then, gradually apply water pressure from the back surface of the porous separation membrane formed on the porous reinforcing sheet, that is, the nonwoven fabric side, or the membrane is peeled from the nonwoven fabric,
Or the pressure at which the membrane and the nonwoven fabric burst at the same time.
Table 1 shows the results.
【００３３】[0033]
【表１】 表１に示す通り、実施例１〜３で得られた本発明のポリ
フッ化ビニリデン多孔質分離膜は、いずれも表面の平均
孔径が０．０２〜０．０５μｍであり、ポリエチレンオ
キサイドの阻止率も７０％以上と優れた分離性能を示し
た。さらに、背圧強度も０．３ＭＰａ以上と優れた機械
的強度を有していた。なお、電子顕微鏡（ＳＥＭ）によ
り膜の断面構造を観察したところ、実施例１〜３の膜は
いずれも膜内部に指状空洞の存在する構造であり、膜の
厚みは各々８５μｍ、７０μｍ、５０μｍであり、膜表
面から１μｍの位置における平均孔径は、各々０．２μ
ｍ、０．１５μｍ、０．０８μｍであった。図３に実施
例１で得られた電子顕微鏡（ＳＥＭ）写真を示す。[Table 1] As shown in Table 1, each of the polyvinylidene fluoride porous separation membranes of the present invention obtained in Examples 1 to 3 has an average pore diameter of 0.02 to 0.05 μm on the surface, and also has a rejection of polyethylene oxide. Excellent separation performance of 70% or more was exhibited. Further, the back pressure strength was 0.3 MPa or more, and had excellent mechanical strength. When the cross-sectional structure of the film was observed by an electron microscope (SEM), the films of Examples 1 to 3 each had a structure in which finger-like cavities existed inside the film, and the thicknesses of the films were 85 μm, 70 μm, and 50 μm, respectively. And the average pore diameter at a position of 1 μm from the membrane surface is 0.2 μm each.
m, 0.15 μm and 0.08 μm. FIG. 3 shows an electron microscope (SEM) photograph obtained in Example 1.
【００３４】（試験例２）実施例１〜２で得た多孔質分
離膜を用いて背圧強度測定用のホルダーにセットし、０
ＭＰａと０．２ＭＰａの背圧を５秒サイクルで繰り返す
背圧疲労テストを実施したところ、１０万回のテスト後
においても膜の剥離はまったく生じなかった。実施例３
で得た多孔質分離膜を用いて背圧強度測定用のホルダー
にセットし、０ＭＰａと０．３ＭＰａの背圧を５秒サイ
クルで繰り返す背圧疲労テストを実施したところ、２１
万回のテスト後においても膜の剥離はまったく生じなか
った。同様のテストを比較例１のポリスルホン膜ＲＳ３
０で行った場合、０ＭＰａと０．３ＭＰａの背圧では数
回で膜剥離が生じ、０ＭＰａと０．２ＭＰａの背圧では
１５００回で割れが生じた。(Test Example 2) The porous separation membranes obtained in Examples 1 and 2 were set in a holder for measuring the back pressure strength, and
When a back pressure fatigue test in which the back pressure of MPa and 0.2 MPa was repeated in a cycle of 5 seconds was performed, no peeling of the film occurred even after 100,000 tests. Example 3
The porous separation membrane obtained in the above was set in a holder for measuring the back pressure strength, and a back pressure fatigue test in which a back pressure of 0 MPa and 0.3 MPa was repeated at a cycle of 5 seconds was performed.
No delamination of the film occurred after 10,000 tests. A similar test was conducted using the polysulfone membrane RS3 of Comparative Example 1.
When the test was performed at 0, film peeling occurred several times at a back pressure of 0 MPa and 0.3 MPa, and cracks occurred at 1500 times at a back pressure of 0 MPa and 0.2 MPa.
【００３５】[0035]
【発明の効果】以上のように、本発明のポリフッ化ビニ
リデン多孔質分離膜は極めて機械的強度、繰り返し疲労
強度に優れた平膜であり、従来の平膜と比較した際、透
過性能は同等にもかかわらず、より数多くの繰り返し逆
圧洗浄に耐えることが可能である。さらに塩素に対する
耐性も非常に優れており、海水のろ過といった過酷な条
件のもとでも膜寿命が非常に長く、コストパフォーマン
スに優れた分離膜であるといえる。また、本発明のポリ
フッ化ビニリデン多孔質分離膜は菌体や微粒子を高精度
に分離・除去できると共に、分子量１００万程度の高分
子物質をも分離できる極めて特徴的な分離性能を有し、
従来の精密濾過と限外濾過の中間的な分野への応用が可
能である。As described above, the polyvinylidene fluoride porous separation membrane of the present invention is a flat membrane having extremely excellent mechanical strength and repetitive fatigue strength, and has the same permeability as the conventional flat membrane. Nevertheless, it is possible to withstand more repeated backwashing. Furthermore, it has extremely excellent resistance to chlorine, and has a very long membrane life even under severe conditions such as filtration of seawater, and can be said to be a separation membrane excellent in cost performance. In addition, the polyvinylidene fluoride porous separation membrane of the present invention can separate and remove microbial cells and fine particles with high precision, and has a very characteristic separation performance capable of separating a polymer substance having a molecular weight of about 1,000,000.
Application to the intermediate field between conventional microfiltration and ultrafiltration is possible.
【図１】本発明のポリフッ化ビニリデン多孔質分離膜を
説明するための模式図FIG. 1 is a schematic diagram for explaining a polyvinylidene fluoride porous separation membrane of the present invention.
【図２】本発明の一実施の形態の連続製膜方法を説明す
る工程図FIG. 2 is a process chart illustrating a continuous film forming method according to an embodiment of the present invention.
【図３】本発明の実施例１で得られた分離膜の表層部分
の電子顕微鏡（ＳＥＭ）写真FIG. 3 is an electron microscope (SEM) photograph of a surface portion of the separation membrane obtained in Example 1 of the present invention.
１ 繰出し機 ２ 支持体 ３ 製膜溶液 ４ バーコータ− ５ 液膜 ６ 相分離ゾーン ７ 凝固水槽 ８ 多孔質分離膜 ９ 水洗槽 １０ 巻取機 ２０ ポリフッ化ビニリデン多孔質分離膜 ２１ 多孔性補強シート ２２ 分離機能を有する膜 REFERENCE SIGNS LIST 1 feeding machine 2 support 3 film forming solution 4 bar coater 5 liquid film 6 phase separation zone 7 coagulation water tank 8 porous separation membrane 9 washing tank 10 winder 20 polyvinylidene fluoride porous separation membrane 21 porous reinforcing sheet 22 separation Functional membrane
───────────────────────────────────────────────────── フロントページの続き (72)発明者 石原 悟 大阪府茨木市下穂積１丁目１番２号 日東 電工株式会社内 Ｆターム(参考） 4D006 LA06 MA09 MA23 MA31 MB16 MC29 MC29X NA04 NA10 NA13 NA16 NA40 NA46 PA01 PB03 PB08 PB22 PB24 PC02 PC17 PC42 PC43 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Satoru Ishihara 1-1-2 Shimohozumi, Ibaraki-shi, Osaka Nitto Denko Corporation F-term (reference) 4D006 LA06 MA09 MA23 MA31 MB16 MC29 MC29X NA04 NA10 NA13 NA16 NA40 NA46 PA01 PB03 PB08 PB22 PB24 PC02 PC17 PC42 PC43
Claims (2)
多孔質膜が多孔性補強シートの孔内に部分的に投錨され
て支持された分離膜であって、有効直径２３ｍｍの円孔
型ホルダーに保持して背圧０ＭＰａと背圧０．２ＭＰａ
とを繰り返す背圧疲労テストでの耐久繰り返し回数が５
万回以上であることを特徴とするポリフッ化ビニリデン
多孔質分離膜。1. A separation membrane in which a polyvinylidene fluoride porous membrane having a separation function is partially anchored and supported in a hole of a porous reinforcing sheet, and held by a circular holder having an effective diameter of 23 mm. Back pressure 0MPa and back pressure 0.2MPa
The number of endurance cycles in the back pressure fatigue test is 5
A polyvinylidene fluoride porous separation membrane which is subjected to 10,000 times or more.
〜０．２ｍｍであり、かつ密度が０．５〜０．８ｇ／ｃ
ｍ3 である請求項１記載のポリフッ化ビニリデン多孔質
分離膜。2. The thickness of the porous reinforcing sheet is 0.08.
0.2 mm and a density of 0.5 to 0.8 g / c
The polyvinylidene fluoride porous separation membrane according to claim 1, wherein m 3 is m 3 .
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| JP2006326497A (en) * | 2005-05-26 | 2006-12-07 | Daicel Chem Ind Ltd | Semi-permeable membrane for water treatment and its production method |
| JP2009536573A (en) * | 2006-05-09 | 2009-10-15 | ポーレックス コーポレイション | Porous composite membrane material and its application |
| JP4809346B2 (en) * | 2004-08-11 | 2011-11-09 | ヴラームス インステリング ヴール テクノロギシュ オンデルゾーク （ヴイアイティーオー） | Web-reinforced separation membrane and continuous manufacturing method thereof |
| US8349400B2 (en) | 2003-11-04 | 2013-01-08 | Porex Corporation | Method of making a composite porous material |
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| JPH0278425A (en) * | 1987-06-26 | 1990-03-19 | Rhone Poulenc Rech | Hydrophilic and dryable semipermeable membrane based on polyvinylidene fluoride |
| JPH09313905A (en) * | 1996-05-23 | 1997-12-09 | Nitto Denko Corp | Polysulfone porous separating membrane |
| JPH10225626A (en) * | 1997-02-17 | 1998-08-25 | Nitto Denko Corp | Spiral membrane element |
| JP2001079368A (en) * | 1999-09-20 | 2001-03-27 | Hour Seishi Kk | Separation membrane-supporting body ad production thereof |
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| US8349400B2 (en) | 2003-11-04 | 2013-01-08 | Porex Corporation | Method of making a composite porous material |
| JP4809346B2 (en) * | 2004-08-11 | 2011-11-09 | ヴラームス インステリング ヴール テクノロギシュ オンデルゾーク （ヴイアイティーオー） | Web-reinforced separation membrane and continuous manufacturing method thereof |
| JP2006326497A (en) * | 2005-05-26 | 2006-12-07 | Daicel Chem Ind Ltd | Semi-permeable membrane for water treatment and its production method |
| JP2009536573A (en) * | 2006-05-09 | 2009-10-15 | ポーレックス コーポレイション | Porous composite membrane material and its application |
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