JP5036211B2 - Ceramic filter and manufacturing method thereof - Google Patents
Ceramic filter and manufacturing method thereof Download PDFInfo
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- JP5036211B2 JP5036211B2 JP2006113620A JP2006113620A JP5036211B2 JP 5036211 B2 JP5036211 B2 JP 5036211B2 JP 2006113620 A JP2006113620 A JP 2006113620A JP 2006113620 A JP2006113620 A JP 2006113620A JP 5036211 B2 JP5036211 B2 JP 5036211B2
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- 239000000919 ceramic Substances 0.000 title claims description 51
- 238000004519 manufacturing process Methods 0.000 title claims description 7
- 229910018072 Al 2 O 3 Inorganic materials 0.000 claims description 32
- 239000011148 porous material Substances 0.000 claims description 32
- 239000002245 particle Substances 0.000 claims description 28
- 239000000843 powder Substances 0.000 claims description 28
- 239000002994 raw material Substances 0.000 claims description 25
- 239000012528 membrane Substances 0.000 claims description 22
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 21
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 20
- 238000009826 distribution Methods 0.000 claims description 18
- 238000000034 method Methods 0.000 claims description 17
- 239000000758 substrate Substances 0.000 claims description 12
- 238000001914 filtration Methods 0.000 description 35
- 238000005260 corrosion Methods 0.000 description 6
- 230000007797 corrosion Effects 0.000 description 6
- 238000010304 firing Methods 0.000 description 6
- 230000007423 decrease Effects 0.000 description 5
- 239000006185 dispersion Substances 0.000 description 5
- 239000012535 impurity Substances 0.000 description 5
- 238000010298 pulverizing process Methods 0.000 description 5
- 238000000746 purification Methods 0.000 description 5
- 239000002002 slurry Substances 0.000 description 5
- 230000015572 biosynthetic process Effects 0.000 description 4
- 230000000052 comparative effect Effects 0.000 description 4
- 239000013078 crystal Substances 0.000 description 4
- 239000002344 surface layer Substances 0.000 description 4
- 230000003247 decreasing effect Effects 0.000 description 3
- 239000010419 fine particle Substances 0.000 description 3
- 239000007791 liquid phase Substances 0.000 description 3
- 238000000576 coating method Methods 0.000 description 2
- 238000007598 dipping method Methods 0.000 description 2
- 238000000926 separation method Methods 0.000 description 2
- 239000002351 wastewater Substances 0.000 description 2
- 239000005995 Aluminium silicate Substances 0.000 description 1
- 238000007088 Archimedes method Methods 0.000 description 1
- 238000004131 Bayer process Methods 0.000 description 1
- SMZOGRDCAXLAAR-UHFFFAOYSA-N aluminium isopropoxide Chemical compound [Al+3].CC(C)[O-].CC(C)[O-].CC(C)[O-] SMZOGRDCAXLAAR-UHFFFAOYSA-N 0.000 description 1
- 235000012211 aluminium silicate Nutrition 0.000 description 1
- 235000013361 beverage Nutrition 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000004033 diameter control Methods 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 239000007888 film coating Substances 0.000 description 1
- 238000009501 film coating Methods 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 235000013305 food Nutrition 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 238000005342 ion exchange Methods 0.000 description 1
- NLYAJNPCOHFWQQ-UHFFFAOYSA-N kaolin Chemical compound O.O.O=[Al]O[Si](=O)O[Si](=O)O[Al]=O NLYAJNPCOHFWQQ-UHFFFAOYSA-N 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 150000002736 metal compounds Chemical class 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 229920000620 organic polymer Polymers 0.000 description 1
- 239000012071 phase Substances 0.000 description 1
- 238000007650 screen-printing Methods 0.000 description 1
- 238000005245 sintering Methods 0.000 description 1
- 238000003980 solgel method Methods 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
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- Compositions Of Oxide Ceramics (AREA)
- Separation Using Semi-Permeable Membranes (AREA)
Description
本発明は、セラミックフィルター、とくに水処理用フィルター及びその製造方法に関する。 The present invention relates to a ceramic filter, particularly a water treatment filter and a method for producing the same.
セラミック濾過膜は廃水、上水等の浄化や溶液、食品、飲料等の濾過膜として使用されている。
従来、この分野の濾過膜としては金属や有機高分子などがその材料として用いられてきたが、耐食性、耐熱性等の点からセラミックスに比べて低く、また、寿命も短いため濾過膜の頻繁な交換が必要であった。
このため、セラミックフィルターが濾過膜として近年使用が増加しているが、その材料としては、主としてアルミナ質の焼結体が用いられている。しかしながら、微細孔径のアルミナ質濾過膜の製造に関しては、細孔径は平均結晶粒径に大きく依存するため、原料粉末として目的とする細孔径に応じて極めて微細で粒度分布の狭い原料粉末の使用が不可欠である。この様な微細な原料粉末はコストが高く、また、微細であるがために焼結性が高くなり、その結果、細孔径制御が非常に限定された条件で行う必要があった。
Ceramic filtration membranes are used as purification membranes for waste water, clean water, etc., and filtration membranes for solutions, foods, beverages and the like.
Conventionally, metals and organic polymers have been used as filtration membranes in this field, but they are lower than ceramics in terms of corrosion resistance, heat resistance, etc., and their lifetime is also short, so filtration membranes are frequently used. An exchange was necessary.
For this reason, the use of ceramic filters as filtration membranes has increased in recent years, and as a material for the filter, mainly an alumina sintered body is used. However, for the production of fine pore alumina filtration membranes, the pore diameter largely depends on the average crystal grain size, so it is necessary to use a raw powder with a very fine and narrow particle size distribution as the raw powder. It is essential. Such a fine raw material powder is expensive and has a fine sinterability due to its fineness. As a result, it has been necessary to perform control under conditions in which pore diameter control is very limited.
特許文献１には浄水器用セラミック膜フィルタが開示されているが、このフィルターに使用されるセラミック膜の平均細孔径は、０．２〜０．８μｍであるが、浄水器用セラミック膜としては細孔径が大きいため、精密な上水の濾過は不可能であった。そのため、特許文献２にはゾル−ゲル法で成膜し、膜の平均細孔径が１Å〜１０００Å（０．０００１〜０．１μｍ）を有するセラミック膜が開示されているが、膜形成に有機金属化合物を用いるため成膜に要するコストが非常に高くなる難点があった。 Although the ceramic membrane filter for water purifiers is indicated by patent document 1, the average pore diameter of the ceramic membrane used for this filter is 0.2-0.8 micrometer, but as a ceramic membrane for water purifiers, it is a pore diameter. Therefore, it is impossible to precisely filter the clean water. Therefore, Patent Document 2 discloses a ceramic film formed by a sol-gel method and having an average pore diameter of 1 to 1000 mm (0.0001 to 0.1 μm). Since a compound is used, the cost required for film formation is very high.
本発明の目的は、安価なアルミナ原料粉体を用いたセラミック膜を製膜したセラミックフィルターの製造方法及びそれにより得られるセラミックフィルターを提供する点にある。 An object of the present invention is to provide a method for producing a ceramic filter obtained by forming a ceramic membrane using an inexpensive alumina raw material powder and a ceramic filter obtained thereby.
本発明者らは鋭意研究を重ねてきた結果、ある特定の範囲内にあるアルミナ純度をもつる基体管表面に、アルミナ原料粉体の純度、粒度及び濾過膜厚さを制御してセラミック膜を製膜することにより、安価で高い濾過精度及び濾過能力並びに高い耐食性を有するセラミックフィルター、特に水処理用フィルターが得られることを見出し、ここに本発明を完成したものである。
従来は、微細孔径とするために微粒子からなるアルミナ原料粉体を用いているが、アルミナ原料粉体は、安価なバイヤー法で製造された粉体では粒度分布がシャープな微粒子からなる粉体が得られなかったことから、液相法等で製造されたアルミナ原料粉体が使用されており、このアルミナ原料粉体は価格が高く、また、微粒子であるがため分散に手間がかかるなどの欠点があった。また、アルミニウムイソプロポキシド等の有機金属化合物をコーティングし、熱処理して濾過膜を形成する方法が採用されているが、これもコストが高くなる。
しかしながら、本発明は安価なバイヤー法で製造されたアルミナ原料粉体を粉砕・分散によりある特定の範囲内の粒度分布に調整し、アルミナ純度をある特定の範囲内にすることで安価で高い濾過精度及び濾過能力を有するセラミックフィルターとすることができることを見出した。
本発明のセラミックフィルターの膜の製膜に用いるアルミナ原料粉体はバイヤー法で製造されているＡｌ２Ｏ３粉体であるため、焼結性が液相法で作製されたＡｌ２Ｏ３粉体に比べて低いが、微量の不純物を含有していることと、粒度分布を制御し、製膜用スラリーをよく分散させることで、低温焼成でもＡｌ２Ｏ３結晶粒子が成長することなく、膜として十分なＡｌ２Ｏ３結晶粒子同士の結合が可能である。しかしながら、従来の方法によるセラミック膜に比べて濾過能力は低いが、膜厚をある特定の範囲内にすることで改善することも併せて見出したものである。
As a result of intensive studies, the present inventors have determined that a ceramic membrane is formed on the surface of a substrate tube having an alumina purity within a specific range by controlling the purity, particle size and filtration film thickness of the alumina raw material powder. By forming a film, it has been found that a ceramic filter, particularly a water treatment filter, which is inexpensive and has high filtration accuracy and filtration ability and high corrosion resistance can be obtained, and the present invention has been completed here.
Conventionally, alumina raw material powder made of fine particles has been used to obtain a fine pore diameter, but alumina raw material powder is powder made of fine particles having a sharp particle size distribution in a powder produced by an inexpensive buyer method. Since it was not obtained, alumina raw material powder manufactured by the liquid phase method is used, and this alumina raw material powder is expensive and has disadvantages such as being troublesome to disperse because it is fine particles was there. In addition, a method in which an organic metal compound such as aluminum isopropoxide is coated and heat treated to form a filtration membrane is employed, but this also increases the cost.
However, the present invention adjusts the alumina raw material powder produced by an inexpensive buyer method to a particle size distribution within a certain range by pulverization / dispersion, and makes the alumina purity within a certain range inexpensive and high filtration. It has been found that a ceramic filter having accuracy and filtration ability can be obtained.
Since alumina raw material powder used for the film formation of the ceramic filter membrane of the present invention is an Al 2 O 3 powder is produced by the Bayer process, Al 2 O 3 powder sintering property is produced by a liquid phase method Although it is low compared to the body, it contains a trace amount of impurities, and by controlling the particle size distribution and well dispersing the slurry for film formation, Al 2 O 3 crystal particles do not grow even at low temperature firing, Al 2 O 3 crystal particles sufficient as a film can be bonded to each other. However, although the filtering ability is lower than that of the ceramic membrane by the conventional method, it has also been found that the film thickness can be improved by making the film thickness within a specific range.
すなわち、本発明の第１は、（ａ）Ａｌ２Ｏ３含有量が８３〜９４重量％からなるアルミナ質基体管表面に、（ｂ）Ａｌ２Ｏ３含有量が９８重量％以上、（ｃ）バブルポイント法で測定したモード径が０．０５〜０．３μｍ、（ｄ）最大細孔径が０．８μｍ以下であるセラミック膜を製膜したセラミックフィルターであり、（ｅ）その気孔率が３５％以上であることを特徴とするセラミックフィルターに関する。
本発明の第２は、液圧１ｋｇｆ／ｃｍ２で透水させた時の純水透過流速が２５ｍ３／ｍ２／ｄａｙ、好ましくは３０ｍ３／ｍ２／ｄａｙ以上である請求項１記載のセラミックフィルターに関する。
本発明の第３は、膜厚が２０μｍ以下である請求項１または２記載のセラミックフィルターに関する。
本発明の第４は、Ａｌ２Ｏ３含有量が９９重量％以上からなるＡｌ２Ｏ３原料粉体を、平均粒子径が０．５〜２μｍ、粒度分布変動係数が４０〜６０になるように粉砕・分散し、Ａｌ２Ｏ３含有量が８３〜９４重量％からなるアルミナ質基体管表面にコーティングし、１２００〜１４００℃で焼成すること特徴とする請求項１〜３いずれか記載のセラミックフィルターの製造方法に関する。
That is, according to the first aspect of the present invention, (a) an alumina base tube surface having an Al 2 O 3 content of 83 to 94% by weight, (b) an Al 2 O 3 content of 98% by weight or more, (c ) A ceramic filter formed with a ceramic membrane having a mode diameter measured by the bubble point method of 0.05 to 0.3 μm, and (d) a maximum pore size of 0.8 μm or less, and (e) its porosity is 35 It is related with the ceramic filter characterized by being more than%.
The ceramic according to claim 1, wherein the second aspect of the present invention has a pure water permeation flow rate of 25 m 3 / m 2 / day, preferably 30 m 3 / m 2 / day or more when permeated at a hydraulic pressure of 1 kgf / cm 2. Regarding filters.
3rd of this invention is related with the ceramic filter of Claim 1 or 2 whose film thickness is 20 micrometers or less.
The fourth aspect of the present invention is that an Al 2 O 3 raw material powder having an Al 2 O 3 content of 99% by weight or more has an average particle size of 0.5 to 2 μm and a particle size distribution variation coefficient of 40 to 60. The ceramic according to any one of claims 1 to 3, wherein the ceramic is pulverized and dispersed, coated on an alumina base tube surface having an Al 2 O 3 content of 83 to 94% by weight, and fired at 1200 to 1400 ° C. The present invention relates to a method for manufacturing a filter.
以下に本発明のセラミックフィルターが充足すべき各要件について詳細に説明する。
（ａ）Ａｌ２Ｏ３含有量が８３〜９４重量％からなるアルミナ質基体管を用いる点。
本発明においては、Ａｌ２Ｏ３が８３〜９４重量％、好ましくは８５〜９２重量％含有しているアルミナ質基体管を用いることによって、基体管と膜との密着性を良好にすることができる。Ａｌ２Ｏ３含有量が８３重量％未満の場合は、不純物量が多くなり、焼結性が高く、膜との密着性が高くなりすぎ、気孔が少なくなって濾過能力の低下をきたすので好ましくない。一方、Ａｌ２Ｏ３含有量が９４重量％を超えるとＡｌ２Ｏ３以外の成分量が少なくなり、ガラス相量が少なくなって焼結性が低下し、膜との密着性が低下し、膜の剥がれ等が発生するので好ましくない。
なお、本発明においては、用いるアルミナ質基体管は、上記アルミナ含有量以外に、バブルポイント法で測定した気孔分布のモード径が０．１５〜０．５μｍであり、気孔率が２０〜５０％であることが本発明のセラミックフィルターの濾過精度及び濾過能力を最大限に引き出せるという点から大変好ましい。さらに本発明では、バイヤー法により製造したＡｌ２Ｏ３原料粉体を用い、粒度分布の制御及び組成を制御して製造された基体管を用いることができ、よりコストを安くすることができる。
Hereinafter, each requirement to be satisfied by the ceramic filter of the present invention will be described in detail.
(A) Aluminous substrate tube having an Al 2 O 3 content of 83 to 94% by weight is used.
In the present invention, by using an alumina base tube containing 83 to 94% by weight, preferably 85 to 92% by weight of Al 2 O 3 , the adhesion between the base tube and the film can be improved. it can. When the Al 2 O 3 content is less than 83% by weight, the amount of impurities is increased, the sinterability is high, the adhesion to the film is too high, the pores are reduced, and the filtration capacity is reduced, which is preferable. Absent. On the other hand, when the content of Al 2 O 3 exceeds 94% by weight, the amount of components other than Al 2 O 3 decreases, the amount of glass phase decreases, the sinterability decreases, and the adhesion with the film decreases. Since peeling of the film occurs, it is not preferable.
In the present invention, the alumina base tube used has a pore distribution mode diameter of 0.15 to 0.5 μm and a porosity of 20 to 50% in addition to the alumina content. It is very preferable from the point that the filtration accuracy and filtration ability of the ceramic filter of the present invention can be maximized. Furthermore, in the present invention, it is possible to use a base tube manufactured by controlling the particle size distribution and controlling the composition using Al 2 O 3 raw material powder manufactured by the Bayer method, and the cost can be further reduced.
（ｂ）Ａｌ２Ｏ３含有量が９８重量％以上からなる点。
本発明においては、Ａｌ２Ｏ３含有量が９８重量％以上、好ましくは９８．５重量％以上であることが必要である。９８重量％未満の場合は、焼結性が高くなり、膜自身の密度が高くなって気孔率が低下し、濾過能力が低下するだけでなく、耐食性も低くなり、非処理物に含有される成分に侵され、膜の劣化が速くなり、剥がれ等の問題を引き起こすので好ましくない。上限は９９．８重量％程度である。
(B) Al 2 O 3 content is 98% by weight or more.
In the present invention, the Al 2 O 3 content needs to be 98% by weight or more, preferably 98.5% by weight or more. If it is less than 98% by weight, the sinterability is increased, the density of the film itself is increased, the porosity is decreased, the filtration performance is decreased, and the corrosion resistance is also decreased, so that it is contained in an untreated product. It is not preferable because it is affected by the components and the film is rapidly deteriorated and causes problems such as peeling. The upper limit is about 99.8% by weight.
（ｃ）バブルポイント法で測定したモード径が０．０５〜０．３μｍである点。
本発明においては、バブルポイント法で測定したモード径が０．０５〜０．３μｍ、好ましくは０．０７〜０．２μｍであることが必要である。モード径が０．０５μｍ未満の場合は、濾過能力が低下するので好ましくなく、０．３μｍを越える場合には濾過による浄化や分離が不十分となるので好ましくない。
なお、バブルポイント法によるモード径の測定はＡＳＴＭ Ｆ３１６−７０に準拠し、媒体としてフッ素系不活性溶液を用いて測定するものである。
(C) The mode diameter measured by the bubble point method is 0.05 to 0.3 μm.
In the present invention, it is necessary that the mode diameter measured by the bubble point method is 0.05 to 0.3 μm, preferably 0.07 to 0.2 μm. When the mode diameter is less than 0.05 μm, the filtration capacity is lowered, which is not preferable. When the mode diameter exceeds 0.3 μm, purification and separation by filtration become insufficient, which is not preferable.
In addition, the measurement of the mode diameter by the bubble point method is based on ASTM F316-70, and measures using a fluorine-type inert solution as a medium.
（ｄ）最大細孔径が０．８μｍ以下である点。
本発明においては、最大細孔径が０．８μｍ以下、好ましくは０．６μｍ以下であることが必要である。最大細孔径が０．８μｍを越える場合には、濾過能力は大きくなるが、濾過精度の低下をきたし、濾過による浄化や分離が不十分となるので好ましくない。下限は０．３μｍ程度である。
(D) The maximum pore diameter is 0.8 μm or less.
In the present invention, the maximum pore diameter needs to be 0.8 μm or less, preferably 0.6 μm or less. When the maximum pore diameter exceeds 0.8 μm, the filtration capacity is increased, but the filtration accuracy is lowered, and purification and separation by filtration are insufficient, which is not preferable. The lower limit is about 0.3 μm.
（ｅ）気孔率が３５％以上である点。
本発明においては、セラミックフィルターとしての気孔率が３５％以上、好ましくは３７％以上であることが必要である。気孔率が３５％未満の場合は、貫通気孔量が低下し、濾過能力が低下するので好ましくない。なお、気孔率の測定はアルキメデス法（ＪＩＳ Ｒ１６３４に準拠）により行う。上限は５０％程度である。
(E) The porosity is 35% or more.
In the present invention, the porosity of the ceramic filter needs to be 35% or more, preferably 37% or more. A porosity of less than 35% is not preferable because the amount of through pores is reduced and the filtration capacity is reduced. The porosity is measured by the Archimedes method (based on JIS R1634). The upper limit is about 50%.
（ｆ）液圧１ｋｇｆ／ｃｍ２で透水させた時の純水透過流速が２５ｍ３／ｍ２／ｄａｙ以上である点。
本発明においては、液圧１ｋｇｆ／ｃｍ２で透水させた時の純水透過流速が２５ｍ３／ｍ２／ｄａｙ以上、好ましくは３０ｍ３／ｍ２／ｄａｙ以上を有することが必要である。純粋透過流速が２５ｍ３／ｍ２／ｄａｙ未満の場合は濾過能力が低くなり、好ましくない。上限は７０ｍ３／ｍ２／ｄａｙ程度である。
なお、本発明では純水透過流速は外径φ１２ｍｍ、内径φ９ｍｍ、長さ１００ｍｍの基体管の外表面に膜を製膜したチューブをサンプルに用いて、２５℃のイオン交換水により液圧１ｋｇｆ／ｃｍ２の液圧をかけた時の時間当たりの透水量（ｍ３）から下式により求める方法で測定したものである。
In the present invention, it is necessary that the pure water permeation flow rate when water is permeated at a hydraulic pressure of 1 kgf / cm 2 is 25 m 3 / m 2 / day or more, preferably 30 m 3 / m 2 / day or more. When the pure permeation flow rate is less than 25 m 3 / m 2 / day, the filtration capacity is lowered, which is not preferable. The upper limit is about 70 m 3 / m 2 / day.
In the present invention, the pure water permeation flow rate is 1 kgf / pressure with ion exchange water at 25 ° C. using a tube having a membrane formed on the outer surface of a base tube having an outer diameter of φ12 mm, an inner diameter of φ9 mm, and a length of 100 mm. It is measured by the method of obtaining from the water permeation amount (m 3 ) per hour when a fluid pressure of cm 2 is applied according to the following formula.
（ｇ）膜厚が２０μｍ以下である点。
本発明において、膜厚は２０μｍ以下、好ましくは１５μｍ以下であることが必要である。
膜厚が２０μｍを越える場合には、膜部分での濾過抵抗が高くなり、濾過能力の低下をきたすので好ましくない。下限は８μｍ程度である。
膜厚はある程度厚い方が高精度の浄化、分離ができる。従来のセラミックフィルターは粒度を精密に整粒した原料粉体を用いているため、コストが高い反面、濾過能力が高いので、膜厚を厚くできるが、本発明のセラミックフィルターはコストが低い反面、濾過能力が従来のセラミックフィルターに比べて低い。しかしながら、従来の膜より結晶粒径分布を広くすることで、膜厚が薄くても濾過精度を低下させることなく、また、濾過能力の低い分を膜厚を薄くすることで補うことが出来る。また、膜厚を薄くすると製膜時のコーティング回数を減少させることができ、それによってコスト低減につながるメリットがある。
なお、膜厚の測定は、作製したセラミックフィルターの断面をＳＥＭ（走査電子顕微鏡）で観察することにより行った。
(G) The film thickness is 20 μm or less.
In the present invention, the film thickness needs to be 20 μm or less, preferably 15 μm or less.
When the film thickness exceeds 20 μm, the filtration resistance at the membrane part becomes high and the filtration capacity is lowered, which is not preferable. The lower limit is about 8 μm.
A thicker film can be purified and separated with higher accuracy. Since the conventional ceramic filter uses raw material powder with a precisely sized particle size, the cost is high, but the filtration ability is high, so the film thickness can be increased, but the ceramic filter of the present invention is low in cost, Filtration capacity is low compared to conventional ceramic filters. However, by making the crystal grain size distribution wider than that of the conventional film, even if the film thickness is small, the filtration accuracy is not lowered, and the low filtering ability can be compensated for by reducing the film thickness. In addition, if the film thickness is reduced, the number of coatings during film formation can be reduced, which has the advantage of reducing costs.
The film thickness was measured by observing a cross section of the produced ceramic filter with a SEM (scanning electron microscope).
本発明のフィルターは基体管の外表面もしくは内表面の片面、もしくは両面にセラミック膜を製膜した構造をしており、被処理物はセラミック膜で濾過され、濾過された被処理物は基体管を通過してフィルターの外へ排出される。そのため、基体管の気孔径はセラミック膜の気孔径よりも大きくする必要があり、基体管の気孔径とセラミック膜の気孔径とを適宜設定することで濾過精度及び濾過能力を最大限引き出すことができる。
なお、基体管の形状は、管状だけに限らず、板形状でも良い。
The filter of the present invention has a structure in which a ceramic film is formed on one surface or both surfaces of the outer surface or the inner surface of a substrate tube, the object to be processed is filtered with the ceramic film, and the filtered object to be processed is the substrate tube. It passes through and is discharged out of the filter. Therefore, the pore diameter of the base tube needs to be larger than the pore diameter of the ceramic membrane, and the filtration accuracy and filtration capacity can be maximized by appropriately setting the pore diameter of the base tube and the pore size of the ceramic membrane. it can.
The shape of the base tube is not limited to a tubular shape, and may be a plate shape.
本発明のセラミックフィルターの製造方法について説明する。
本発明では、純度９９重量％以上、好ましくは９９．５重量％以上で平均粒子径が０．５〜２．５μｍ、好ましくは０．６〜２．０μｍのＡｌ２Ｏ３原料粉体を用いる。請求項１のセラミックフィルターにおけるＡｌ２Ｏ３含有量を９８重量％以上としているのに対して、原料中のＡｌ２Ｏ３含有量を９９重量％以上としている理由は、原料を粉砕・分散する工程において、粉砕機などから微量の不純物が混入してくるため、製品のセラミックフィルター中のＡｌ２Ｏ３含有量より原料中のＡｌ２Ｏ３含有量を高くしておく必要がある。このＡｌ２Ｏ３原料はバイヤー法等で製造された原料粉体を用いることができる。バイヤー法で製造されたＡｌ２Ｏ３原料粉体はコストが安いため有利である。Ａｌ２Ｏ３純度が９９．０重量％未満の場合はセラミック膜に含有される不純物が多くなり、耐食性の低下などをきたすので好ましくない。平均粒子径が０．５μｍ未満の場合は、得られたセラミック膜の気孔径が小さくなりすぎるので好ましくなく、２．５μｍを越える場合には所定の粒度分布にするまでの粉砕・分散時間が長くなり、粉砕機の摩耗による不純物が多く混入するため好ましくない。所定の粒度をもつＡｌ２Ｏ３原料粉体を湿式でポットミルやアトリッションミル等により水で粉砕・分散する。粉砕・分散後の平均粒子径及び粒度分布は粉砕・分散条件（使用するボール径や処理時間）でコントロールする。粉砕・分散後の平均粒子径は０．５〜２μｍであることが必要で、好ましくは０．７〜１．８μｍにする。平均粒子径が０．５μｍ未満の場合は、気孔径が小さくなりすぎ、２μｍを越える場合には気孔径が大きくなりすぎるので好ましくない。
本発明におけるＡｌ２Ｏ３原料粉末の粒度分布は下記で示す粒度分布変動係数が４０〜６０、好ましくは４５〜６０であることが必要である。変動係数は粒度の頻度分布を算術平均した値である平均粒子径に対する粒度分布の広がり具合を表す数値で、この値が大きいほど分布の広がりが大きいことを示す。
以上に述べた条件を満足する粉砕・分散スラリーを用いて基体管の「被濾過物が接触する表面」にスプレー、スクリーン印刷、浸漬法等の方法で、焼成後の膜厚が２０μｍ以下になるようにコーティングし、乾燥の後、１２００〜１４００℃、好ましくは１２５０〜１３５０℃で焼成してセラミック膜を形成する。
A method for producing the ceramic filter of the present invention will be described.
In the present invention, Al 2 O 3 raw material powder having a purity of 99% by weight or more, preferably 99.5% by weight or more and an average particle size of 0.5 to 2.5 μm, preferably 0.6 to 2.0 μm is used. . The reason why the Al 2 O 3 content in the raw material is 99% by weight or more, whereas the Al 2 O 3 content in the ceramic filter of claim 1 is 98% by weight or higher is that the raw material is pulverized and dispersed. in step, since traces of impurities from such mills come contaminated, it is necessary to increase the content of Al 2 O 3 in the raw materials from Al 2 O 3 content in the ceramic filter products. As the Al 2 O 3 raw material, a raw material powder produced by the Bayer method or the like can be used. The Al 2 O 3 raw material powder produced by the Bayer method is advantageous because of its low cost. If the purity of Al 2 O 3 is less than 99.0% by weight, the amount of impurities contained in the ceramic film increases, resulting in a decrease in corrosion resistance. When the average particle size is less than 0.5 μm, the pore size of the obtained ceramic membrane is too small, which is not preferable. When it exceeds 2.5 μm, the pulverization / dispersion time until a predetermined particle size distribution is obtained is long. Therefore, a large amount of impurities due to wear of the pulverizer is mixed, which is not preferable. The Al 2 O 3 raw material powder having a predetermined particle size is pulverized and dispersed with water in a pot mill, an attrition mill or the like in a wet manner. The average particle size and particle size distribution after pulverization / dispersion are controlled by pulverization / dispersion conditions (ball diameter used and processing time). The average particle size after pulverization / dispersion needs to be 0.5 to 2 μm, preferably 0.7 to 1.8 μm. When the average particle diameter is less than 0.5 μm, the pore diameter becomes too small, and when it exceeds 2 μm, the pore diameter becomes too large.
The particle size distribution of the Al 2 O 3 raw material powder in the present invention is required to have a particle size distribution variation coefficient of 40 to 60, preferably 45 to 60 shown below. The coefficient of variation is a numerical value representing the extent of the particle size distribution with respect to the average particle diameter, which is an arithmetic average value of the particle size frequency distribution. The larger the value, the greater the distribution spread.
Using a pulverized / dispersed slurry that satisfies the above-mentioned conditions, the film thickness after firing is 20 μm or less by spraying, screen printing, dipping, etc. on the “surface to be filtered” of the base tube. After coating and drying, the ceramic film is formed by firing at 1200 to 1400 ° C, preferably 1250 to 1350 ° C.
本発明のセラミックフィルターは安価で製造でき、耐食性、耐熱性に優れ、精密な濾過が可能であって、濾過能力が高く、耐久性に優れた特徴を有している。
本発明のセラミックフィルターは、廃水の浄化や中水、上水の浄化に用いることができ、耐食性が良好なため様々な被濾過物に対応できる。
The ceramic filter of the present invention can be manufactured at low cost, has excellent corrosion resistance and heat resistance, enables precise filtration, has high filtering ability, and has excellent durability.
The ceramic filter of the present invention can be used for the purification of waste water, the purification of middle water, and clean water, and can cope with various objects to be filtered because of its good corrosion resistance.
以下、実施例及び比較例により具体的に説明するが、本発明はこれらの実施例により何ら限定されるものでない。 Hereinafter, although an example and a comparative example explain concretely, the present invention is not limited at all by these examples.
実施例１〜５、比較例１〜５
純度が９９．７％のバイヤー法で製造されたアルミナ原料粉体を、水を用いて湿式で粉砕・分散して、膜コーティング用スラリーを作製した。水：粉体の重量比は通常７０：３０〜３０：７０であり、本例は４０：６０で行った。比較例Ｎｏ．４は液相法より作製したアルミナ原料粉体を用いた。実施例Ｎｏ．５及び比較例Ｎｏ．３はＡｌ２Ｏ３原料粉体にカオリンを添加した。得られたスラリーの平均粒子径及び変動係数を表１に示す。得られたスラリーを表１に示す特性を有する基体管（ψ１２×ψ９×１００ｍｍ）の外表面に浸漬法にてコーティングし、乾燥の後、電気炉で焼成してセラミックフィルターを作製した。得られたセラミック膜の特性を表２に示す。なお、各基体管の気孔モード径及び気孔率は、基体管のみを記載の焼成温度で焼成した時の値を示す。基体管に表面層の膜を付けた状態で気孔径を測定すると、表面層の膜の気孔径が測定され、基体管の気孔径は測定できない。そこで、基体管の気孔径を知るためには、表面層の膜がない状態で、表面層を形成させる温度で焼成し、その焼成後の基体管の気孔径を測定することにより、はじめて基体管自体の気孔モード径や気孔径を求めることができる。
Examples 1-5, Comparative Examples 1-5
The alumina raw material powder manufactured by the Bayer method having a purity of 99.7% was pulverized and dispersed wet with water to prepare a slurry for film coating. The weight ratio of water: powder is usually 70: 30-30: 70, and this example was carried out at 40:60. Comparative Example No. 4 used the alumina raw material powder produced by the liquid phase method. Example No. 5 and Comparative Example No. 3 added kaolin to the Al 2 O 3 raw material powder. Table 1 shows the average particle size and coefficient of variation of the obtained slurry. The obtained slurry was coated on the outer surface of a base tube (φ12 × φ9 × 100 mm) having the characteristics shown in Table 1 by a dipping method, dried, and then fired in an electric furnace to produce a ceramic filter. Table 2 shows the characteristics of the obtained ceramic film. The pore mode diameter and the porosity of each substrate tube indicate values when only the substrate tube is fired at the firing temperature described. When the pore diameter is measured with the surface layer film attached to the substrate tube, the pore diameter of the surface layer film is measured, and the pore diameter of the substrate tube cannot be measured. Therefore, in order to know the pore diameter of the substrate tube, the substrate tube is first obtained by firing at a temperature at which the surface layer is formed in the absence of the surface layer film, and measuring the pore diameter of the substrate tube after the firing. The own pore mode diameter and pore diameter can be obtained.
Claims (4)
The Al 2 O 3 content consists of 99 wt% or more Al 2 O 3 raw material powder having an average particle size of 0.5 to 2 [mu] m, and pulverized and dispersed so as particle size distribution variation coefficient is 40 to 60, Al The method for producing a ceramic filter according to any one of claims 1 to 3, wherein the surface of the alumina substrate pipe having 2 O 3 content of 83 to 94% by weight is coated and fired at 1200 to 1400 ° C.
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