JP2005112679A - Manufacturing method of a cordierite ceramic honeycomb structure - Google Patents
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- JP2005112679A JP2005112679A JP2003350317A JP2003350317A JP2005112679A JP 2005112679 A JP2005112679 A JP 2005112679A JP 2003350317 A JP2003350317 A JP 2003350317A JP 2003350317 A JP2003350317 A JP 2003350317A JP 2005112679 A JP2005112679 A JP 2005112679A
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- 229910052878 cordierite Inorganic materials 0.000 title claims abstract description 33
- JSKIRARMQDRGJZ-UHFFFAOYSA-N dimagnesium dioxido-bis[(1-oxido-3-oxo-2,4,6,8,9-pentaoxa-1,3-disila-5,7-dialuminabicyclo[3.3.1]nonan-7-yl)oxy]silane Chemical compound [Mg++].[Mg++].[O-][Si]([O-])(O[Al]1O[Al]2O[Si](=O)O[Si]([O-])(O1)O2)O[Al]1O[Al]2O[Si](=O)O[Si]([O-])(O1)O2 JSKIRARMQDRGJZ-UHFFFAOYSA-N 0.000 title claims abstract description 33
- 239000000919 ceramic Substances 0.000 title claims abstract description 15
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 15
- 229920000609 methyl cellulose Polymers 0.000 claims abstract description 38
- 239000001923 methylcellulose Substances 0.000 claims abstract description 38
- 235000010981 methylcellulose Nutrition 0.000 claims abstract description 38
- 238000001035 drying Methods 0.000 claims abstract description 30
- 239000001866 hydroxypropyl methyl cellulose Substances 0.000 claims abstract description 29
- 229920003088 hydroxypropyl methyl cellulose Polymers 0.000 claims abstract description 29
- 235000010979 hydroxypropyl methyl cellulose Nutrition 0.000 claims abstract description 29
- UFVKGYZPFZQRLF-UHFFFAOYSA-N hydroxypropyl methyl cellulose Chemical compound OC1C(O)C(OC)OC(CO)C1OC1C(O)C(O)C(OC2C(C(O)C(OC3C(C(O)C(O)C(CO)O3)O)C(CO)O2)O)C(CO)O1 UFVKGYZPFZQRLF-UHFFFAOYSA-N 0.000 claims abstract description 29
- 239000007864 aqueous solution Substances 0.000 claims abstract description 26
- 239000002994 raw material Substances 0.000 claims abstract description 23
- 238000002156 mixing Methods 0.000 claims abstract description 10
- 238000000465 moulding Methods 0.000 claims description 26
- 239000004927 clay Substances 0.000 claims description 24
- 238000010304 firing Methods 0.000 claims description 3
- 238000004898 kneading Methods 0.000 claims description 3
- 239000013078 crystal Substances 0.000 claims 1
- 230000002093 peripheral effect Effects 0.000 abstract description 22
- 230000014759 maintenance of location Effects 0.000 abstract description 12
- 239000000243 solution Substances 0.000 abstract 1
- 238000001125 extrusion Methods 0.000 description 18
- 239000011230 binding agent Substances 0.000 description 13
- 238000005336 cracking Methods 0.000 description 12
- 210000002421 cell wall Anatomy 0.000 description 5
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 5
- 229910001868 water Inorganic materials 0.000 description 5
- 230000007423 decrease Effects 0.000 description 4
- 125000002791 glucosyl group Chemical group C1([C@H](O)[C@@H](O)[C@H](O)[C@H](O1)CO)* 0.000 description 4
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 4
- 238000000034 method Methods 0.000 description 4
- -1 methoxyl group Chemical group 0.000 description 4
- 238000001248 thermal gelation Methods 0.000 description 4
- 210000004027 cell Anatomy 0.000 description 3
- 230000008094 contradictory effect Effects 0.000 description 3
- 239000005995 Aluminium silicate Substances 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 2
- 235000012211 aluminium silicate Nutrition 0.000 description 2
- 238000013329 compounding Methods 0.000 description 2
- 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 2
- 239000000314 lubricant Substances 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 239000000843 powder Substances 0.000 description 2
- 230000002441 reversible effect Effects 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 239000004094 surface-active agent Substances 0.000 description 2
- 239000000454 talc Substances 0.000 description 2
- 229910052623 talc Inorganic materials 0.000 description 2
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 1
- 229920002153 Hydroxypropyl cellulose Polymers 0.000 description 1
- 239000004372 Polyvinyl alcohol Substances 0.000 description 1
- 229910004298 SiO 2 Inorganic materials 0.000 description 1
- WNROFYMDJYEPJX-UHFFFAOYSA-K aluminium hydroxide Chemical compound [OH-].[OH-].[OH-].[Al+3] WNROFYMDJYEPJX-UHFFFAOYSA-K 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 229920002678 cellulose Polymers 0.000 description 1
- 239000001913 cellulose Substances 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 238000001879 gelation Methods 0.000 description 1
- 239000001863 hydroxypropyl cellulose Substances 0.000 description 1
- 235000010977 hydroxypropyl cellulose Nutrition 0.000 description 1
- 230000001771 impaired effect Effects 0.000 description 1
- 238000011835 investigation Methods 0.000 description 1
- 239000004014 plasticizer Substances 0.000 description 1
- 229920002451 polyvinyl alcohol Polymers 0.000 description 1
- 229910052573 porcelain Inorganic materials 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
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Abstract
Description
本発明は、コージェライト質セラミックハニカム構造体を押出成形して製造する方法に関する。 The present invention relates to a method for producing a cordierite ceramic honeycomb structure by extrusion.
自動車等のエンジンから排出される排気ガスを浄化する触媒担体、或いは、セルの流入側と流出側を交互に目封止してハニカムフィルタとし、ディーゼルエンジン等から排出される微粒子を捕集するフィルタとして、コージェライト質セラミックハニカム構造体が使用されている。図１に本発明が対象とするコージェライト質セラミックハニカム構造体（以下、ハニカム構造体と略称することがある）を示し、図１に示す記号で説明する。一般に、このハニカム構造体を製造する際には、カオリン、タルク、アルミナなどのコージェライト化原料と水、有機バインダー、界面活性剤、潤滑剤、可塑剤等の成形助剤、又は必要に応じ造孔剤とを、混合、混練して坏土とし、この坏土を格子状のスリットからなる排出通路とこのスリットの交点に杯土を供給する通路を備える押出用口金を通過させることにより、外周壁１１ａとこの外周壁１１ａの内周側でセル壁１１ｂにより囲まれた多数のセル１１ｃが形成されたハニカム構造を有する成形体を成形する押出成形法が用いられている。次いで、この成形体に、乾燥、焼成を行うことによってハニカム構造体が得られる。
A catalyst carrier that purifies exhaust gas discharged from engines such as automobiles, or a filter that traps particulates discharged from diesel engines, etc. by alternately plugging the inflow side and outflow side of the cell to form a honeycomb filter As such, a cordierite ceramic honeycomb structure is used. FIG. 1 shows a cordierite ceramic honeycomb structure (hereinafter, may be abbreviated as “honeycomb structure”) targeted by the present invention, and will be described using symbols shown in FIG. Generally, when manufacturing this honeycomb structure, raw materials for cordierite such as kaolin, talc and alumina and water, organic binders, surfactants, lubricants, plasticizers and other molding aids, or as necessary The porcelain is mixed and kneaded to make a clay, and this clay is passed through an extrusion die having a discharge passage composed of lattice-like slits and a passage for supplying the clay to the intersection of the slits. An extrusion method is used in which a molded body having a honeycomb structure in which a large number of
上述の押出成形においては、杯土の流動性が重要であり、杯土全体或いは杯土の一部の流動性が低下すると、口金より排出されたハニカム構造の成形体の外周壁表面１１ａが粗面となり、外周壁表面１１ａにめくれや亀裂が発生しやすくなるという問題を有していた。
この流動性の低下については、押出成形時に生じる口金と坏土の摩擦等により坏土温度が上昇し成形助剤がゲル化することにより流動性が低下することが知られている。
良好な流動性を得るためには、コージェライト化原料に添加する水分量を多くする方法が知られている。しかし、この杯土の流動性と成形体の保形性は相反する関係にあり、水分量の調整により流動性を向上させた場合には、成形体の保形性が低下し、成形体を乾燥させるまでの間に成形体自身の自重や、成形体の移動、移載の際の振動により、成形体が変形し、必要な寸法精度が得られないという問題があった。更には、成形体に含まれる多量な水分は、その乾燥過程において生じる成形体の収縮に伴う割れを発生しやすくなるという問題も有していた。この乾燥過程での割れについては、一般的に成形助剤の熱ゲル化強度が高いほど発生しにくいことが知られている。
これらの問題を解決するため、コージェライト化原料に配合される成形助剤には、押出成形時の杯土の流動性確保、成形後の保形性確保、乾燥時の乾燥ワレ防止を目的として、成形助剤の種類及び、その粘度や配合量を最適化する以下のよな検討が行われている。
In the above-described extrusion molding, the fluidity of the clay is important. If the fluidity of the whole clay or a part of the clay is reduced, the outer
With respect to the decrease in fluidity, it is known that the fluidity is lowered by the temperature of the clay rising due to friction between the die and the clay generated during extrusion molding and the forming aid gelling.
In order to obtain good fluidity, a method of increasing the amount of water added to the cordierite forming raw material is known. However, there is a contradictory relationship between the fluidity of the clay and the shape retention of the molded body, and when the fluidity is improved by adjusting the amount of water, the shape retention of the molded body decreases, and There is a problem in that the molded body is deformed due to the weight of the molded body itself, the movement of the molded body, and the vibration during transfer before the drying, and the required dimensional accuracy cannot be obtained. Furthermore, a large amount of water contained in the molded body has a problem that cracks are easily generated due to shrinkage of the molded body during the drying process. It is known that cracks during this drying process are generally less likely to occur as the thermal gelation strength of the molding aid increases.
In order to solve these problems, the molding aid blended in the cordierite forming raw material has the purpose of ensuring fluidity of the clay during extrusion molding, ensuring shape retention after molding, and preventing cracking during drying. The following investigations have been conducted to optimize the types of molding aids and their viscosity and blending amount.
例えば、特許文献１に記載の発明では、コージェライト原料に、粘度が２％水溶液中、２０℃で８０００ｃＰ［＝（ＳＩ単位）８Ｐａ・ｓ］以上で、グルコース環単位中の水酸基がメトキシル基で置換された平均個数からグルコース環単位当たりに付加したヒドロキシプロポキシル基のモル数を引いた数が１.５以上となるメチルセルロースを２〜７％配合し、さらに、粘度が２％水溶液中、２０℃で８０００ｃＰ［＝（ＳＩ単位）８Ｐａ・ｓ］未満のメチルセルロースを０.５〜３％混合し、メチルセルロースの総配合量を２〜７％とすることにより、押出成形時に外周壁表面がめくれたり、亀裂が発生することなく、流動性が良く、乾燥時にクラックが発生しないコージェライトハニカム構造体とする製造方法が開示されている。 For example, in the invention described in Patent Document 1, the cordierite raw material has a viscosity of 8000 cP [= (SI unit) 8 Pa · s] or more at 20 ° C. in a 2% aqueous solution, and the hydroxyl group in the glucose ring unit is a methoxyl group. 2-7% of methylcellulose having a number obtained by subtracting the number of moles of the hydroxypropoxyl group added per glucose ring unit from the average number of substitutions to 1.5 or more is blended, and the viscosity is 20% in an aqueous solution. By mixing 0.5 to 3% of methylcellulose less than 8000 cP [= (SI unit) 8 Pa · s] at a temperature of 2 to 7%, the outer peripheral wall surface may be turned over during extrusion molding. In addition, a manufacturing method is disclosed in which a cordierite honeycomb structure without cracks and having good fluidity and no cracks during drying is disclosed.
また、特許文献２に記載の発明では、セル壁厚の薄いハニカム構造体を得るのに、セルロース誘導体を成形助剤とし、押出成形時における成形性（特に流動性）を改善する開示がある。即ち、特許文献２には、コージェライト化原料バッチ中に、成形助剤として可逆的熱ゲル化性粘結剤を２〜６重量％配合するとともに、２％水溶液粘度（２０℃）で５０００ｃＰ［＝（ＳＩ単位）５Ｐａ・ｓ］以下の粘結剤１と、２％水溶液粘度（２０℃）で２００００ｃＰ［＝（ＳＩ単位）２０Ｐａ・ｓ］以上の粘結剤２からなり、粘結剤１／粘結剤２（重量比）を１０／９０〜５０／５０の範囲で配合、また、粘結剤１及び粘結剤２がメチルセルロース、ヒドロキシプロピルセルロースなどから選択することが好ましいとするコージェライト質セラミックハニカム構造体の製造方法の開示がある。そして、この特許第３０７４１６９号公報に記載の発明によれば、可逆的熱ゲル性粘結剤を２〜６重量％配合する際に、粘結剤１／粘結剤２（重量比）が１０／９０未満では、原料バッチの粘性が高くなり流動性が低下して押出成形時にハニカム成形体が押し出し難くなり、一方、粘結剤１／粘結剤２（重量比）が５０／５０を超えると押出成形後のハニカム成形体の保形性を十分に得ることができないとしている。 In addition, in the invention described in Patent Document 2, there is a disclosure for improving the formability (particularly fluidity) at the time of extrusion molding by using a cellulose derivative as a molding aid in order to obtain a honeycomb structure having a thin cell wall thickness. That is, in Patent Document 2, 2 to 6% by weight of a reversible thermogelling binder as a molding aid is blended in a cordierite forming raw material batch, and a 2% aqueous solution viscosity (20 ° C.) is 5000 cP [ = (SI unit) 5 Pa · s] or lower binder 1 and 2% aqueous solution viscosity (20 ° C.), and binder 2 of 20000 cP [= (SI unit) 20 Pa · s] or higher. / Binder 2 (weight ratio) is blended in the range of 10/90 to 50/50, and the binder 1 and the binder 2 are preferably selected from methyl cellulose, hydroxypropyl cellulose and the like. There is a disclosure of a method for producing a quality ceramic honeycomb structure. According to the invention described in Japanese Patent No. 3074169, when 2 to 6% by weight of the reversible thermogel binder is blended, the binder 1 / binder 2 (weight ratio) is 10%. If it is less than / 90, the viscosity of the raw material batch becomes high and the fluidity decreases, making it difficult to extrude the honeycomb formed body at the time of extrusion molding. On the other hand, the binder 1 / binder 2 (weight ratio) exceeds 50/50. And the shape retention of the honeycomb formed body after extrusion cannot be sufficiently obtained.
しかしながら、本発明者らは、前記特許文献１に開示されている、コージェライト原料に、粘度が２％水溶液中、２０℃で８Ｐａ・ｓ以上で、グルコース環単位中の水酸基がメトキシル基で置換された平均個数からグルコース環単位当たりに付加したヒドロキシプロポキシル基のモル数を引いた数が１.５以上となるメチルセルロースを２〜７％配合し、さらに、粘度が２％水溶液中、２０℃で８Ｐａ・ｓ未満のメチルセルロースを０.５〜３％混合し、メチルセルロースの総配合量を２〜７％とした成形助剤を用いてハニカム構造体の成形を試みたが、特にハニカム構造体の容積が２リットル以上のような大型のハニカム成形体では、外周壁のめくれ、成形体の変形、及び乾燥時のクラック発生を抑えることはできない場合があった。 However, the present inventors have disclosed that the cordierite raw material disclosed in Patent Document 1 has a viscosity of 8 Pa · s or more at 20 ° C. in a 2% aqueous solution, and the hydroxyl group in the glucose ring unit is substituted with a methoxyl group. 2-7% of methylcellulose having a number obtained by subtracting the number of moles of the hydroxypropoxyl group added per glucose ring unit from the average number thus obtained is 1.5 to 7%, and the viscosity is 2% in an aqueous solution at 20 ° C. At this time, an attempt was made to form a honeycomb structure using a molding aid in which 0.5 to 3% of methylcellulose having a viscosity of less than 8 Pa · s was mixed and the total amount of methylcellulose was 2 to 7%. In a large honeycomb molded body having a volume of 2 liters or more, there are cases where it is not possible to suppress the turning of the outer peripheral wall, deformation of the molded body, and generation of cracks during drying.
さらに、本発明者らは、前記特許文献２に開示されているように、２％水溶液粘度（２０℃）で５Ｐａ・ｓ以下のメチルセルロース（Ｍ）と、２％水溶液粘度（２０℃）で２０Ｐａ・ｓ以上のヒドロキシプロピルメチルセルロース（Ｈ）とを、質量比（Ｍ／Ｈ）を１０／９０〜５０／５０の範囲で配合し、メチルセルロース（Ｍ）とヒドロキシプロピルメチルセルロース（Ｈ）の総量を質量で２〜６％とした成形助剤ほかをコージェライト化原料粉末に配合して坏土としハニカム構造体の成形、乾燥、焼成を試みたが、特にハニカム構造体の容積が２リットル以上のような大型のハニカム成形体では、外周壁のめくれ、成形体の変形、及び乾燥時のクラック発生を抑えることはできなかった。 Furthermore, as disclosed in Patent Document 2, the inventors of the present invention have a 2% aqueous solution viscosity (20 ° C.) of 5 Pa · s or less methyl cellulose (M) and a 2% aqueous solution viscosity (20 ° C.) of 20 Pa. -The hydroxypropyl methylcellulose (H) more than s is mix | blended in mass ratio (M / H) in the range of 10 / 90-50 / 50, and the total amount of methylcellulose (M) and hydroxypropyl methylcellulose (H) is a mass. We tried to form, dry and fire the honeycomb structure by blending 2-6% of the molding aid and others into the cordierite-forming raw material powder to make the clay, especially when the volume of the honeycomb structure is 2 liters or more. With a large honeycomb molded body, it was not possible to suppress turning of the outer peripheral wall, deformation of the molded body, and generation of cracks during drying.
本発明は上記課題に鑑みてなされたもので、容積が２リットル以上のような大型のハニカム構造体であっても、成形性（流動性）が良く外周壁めくれが発生しにくく、保形性が良好で変形しにくく、しかも乾燥時に乾燥ワレの発生が少ないハニカム構造体の製造方法を得ることにある。 The present invention has been made in view of the above problems, and even with a large honeycomb structure having a volume of 2 liters or more, the formability (fluidity) is good and the outer peripheral wall is not easily turned over, and the shape retention is good. It is an object to obtain a method for manufacturing a honeycomb structure that is good and hardly deforms, and that generates little cracking during drying.
本発明者らは、特に、セラミックハニカム構造体の容積が２リットル以上の大物の場合について、外周壁表面のめくれ、成形体の変形、及び乾燥クラックの問題を解決するため、各種成形助剤の配合の検討を行った結果、ある一定の性質の成形助剤を組み合わせて配合、使用することにより、坏土の流動性、成形体の保形性、及び耐乾燥割れ性が向上し、上記問題の解決できることを見出し、本発明に想到した。 In order to solve the problems of turning of the outer peripheral wall surface, deformation of the molded body, and dry cracks, especially in the case of a large volume of a ceramic honeycomb structure having a volume of 2 liters or more, the present inventors As a result of the examination of the blending, the above-mentioned problem is improved by blending and using a molding aid having a certain property in combination to improve the fluidity of the clay, the shape retention of the molded body, and the dry cracking resistance. As a result, the present inventors have come up with the present invention.
即ち、本発明は、コージェライト化原料に成形助剤などを配合混練して坏土とした後、この坏土を押出成形により成形、乾燥し、次いで焼成することにより、コージェライト質となるハニカム構造体の製造方法であって、前記坏土中に、２％水溶液粘度（２０℃）で５Ｐａ・ｓ以下のメチルセルロース（Ｍ）と、２％水溶液粘度（２０℃）で２０Ｐａ・ｓ以上のヒドロキシプロピルメチルセルロース（Ｈ）を、前記メチルセルロース（Ｍ）と前記ヒドロキシプロピルメチルセルロース（Ｈ）の質量比（Ｍ／Ｈ）を５０／５０を越え９０／１０以下の範囲で配合することを特徴とする。
そして、本発明において、前記メチルセルロースと前記ヒドロキシプロピルメチルセルロースをコージェライト化原料１００質量部に対して総量で２〜１５質量部配合添加することが好ましく、更には前記メチルセルロースと前記ヒドロキシプロピルメチルセルロースをコージェライト化原料１００質量部に対して総量で７質量部を超え１２質量部以下配合添加することが好ましい。また、コージェライト質セラミックハニカム構造体の容積が２リットル以上であることが好ましい。
That is, the present invention is a honeycomb that becomes cordierite quality by blending and kneading a molding aid or the like with a cordierite forming raw material to form a kneaded material, then molding the kneaded material by extrusion, drying, and then firing. A method for producing a structure, wherein methylcellulose (M) having a 2% aqueous solution viscosity (20 ° C.) of 5 Pa · s or less and hydroxy having a 2% aqueous solution viscosity (20 ° C.) of 20 Pa · s or more are contained in the clay. Propylmethylcellulose (H) is blended such that the mass ratio (M / H) of the methylcellulose (M) to the hydroxypropylmethylcellulose (H) exceeds 50/50 and is not more than 90/10.
In the present invention, the methylcellulose and the hydroxypropylmethylcellulose are preferably added in a total amount of 2 to 15 parts by mass with respect to 100 parts by mass of the cordierite forming raw material, and further the methylcellulose and the hydroxypropylmethylcellulose are cordierite. It is preferable to add more than 7 parts by mass and 12 parts by mass or less with respect to 100 parts by mass of the chemical conversion raw material. The cordierite ceramic honeycomb structure preferably has a volume of 2 liters or more.
次に、本発明の構成要件を説明する。
本発明においては、坏土中に、２％水溶液粘度（２０℃）で５Ｐａ・ｓ以下のメチルセルロース（Ｍ）と、２％水溶液粘度（２０℃）で２０Ｐａ・ｓ以上のヒドロキシプロピルメチルセルロース（Ｈ）を、前記メチルセルロース（Ｍ）と前記ヒドロキシプロピルメチルセルロース（Ｈ）の質量比（Ｍ／Ｈ）を５０／５０を越え９０／１０以下の範囲で配合する。これにより、特に、容積が２リットル以上のような大型のハニカム構造体の押出成形及び乾燥工程で発生する、相反する性質である外周壁表面のめくれ、成形体の変形、及び乾燥クラックの問題を両立して、解決することができる。即ち、メチルセルロース（Ｍ）とヒドロキシプロピルメチルセルロース（Ｈ）の割合を５０／５０を越え９０／１０以下の範囲とすることで、押出成形時の杯土の流動性と成形体の保形性を最適にすることができ、更には熱ゲル化強度も確保できることから、従来解決が困難であった、外周壁表面のめくれ、成形体の変形、及び乾燥クラックの不具合を同時に解消できるからである。
本発明において、２％水溶液粘度（２０℃）で５Ｐａ・ｓ以下のメチルセルロース（Ｍ）と２％水溶液粘度（２０℃）で２０Ｐａ・ｓ以上のヒドロキシプロピルメチルセルロース（Ｈ）の割合を５０／５０を越え９０／１０以下の範囲とすることが重要である。これは両者の質量比（Ｍ／Ｈ）が５０／５０以下、即ちヒドロキシプロピルメチルセルロース（Ｈ）の配合比が多くなる場合、熱ゲル化強度が低下し、成形後の乾燥によりワレが発生することがあるからである。一方、両者の質量比（Ｍ／Ｈ）が９０／１０を超えると、必要以上に配合されたメチルセルロースにより、保形性が低下すると共に、熱ゲル化温度が低下することから、成形温度である約３０℃においてメチルセルロースのゲル化が一部起き始め、杯土の流動性が不安定になり、押出成形の際に外周壁表面が粗面となり、外周壁表面にめくれや亀裂が発生し易くなり最悪の場合は成形できないこともあるからである。従って、質量比（Ｍ／Ｈ）を５０／５０を越え９０／１０以下の範囲で配合する。この質量比割合での配合は、特に、容積が２リットル以上のような大型のハニカム構造体の製造の時に最適である。ここで、２％水溶液粘度（２０℃）で５Ｐａ・ｓ以下のメチルセルロース（Ｍ）と２％水溶液粘度（２０℃）で２０Ｐａ・ｓ以上のヒドロキシプロピルメチルセルロース（Ｈ）の割合は、上記観点から５２／４８以上７５／２５以下の範囲とすることが好ましい。
Next, the configuration requirements of the present invention will be described.
In the present invention, methylcellulose (M) having a 2% aqueous solution viscosity (20 ° C) of 5 Pa · s or less and hydroxypropylmethylcellulose (H) having a 2% aqueous solution viscosity (20 ° C) of 20 Pa · s or more in the clay. Is blended so that the mass ratio (M / H) of the methyl cellulose (M) to the hydroxypropyl methyl cellulose (H) is more than 50/50 and not more than 90/10. Thereby, in particular, the problems of the outer wall surface turning, the deformation of the molded body, and the drying crack, which are contradictory properties, are generated in the extrusion and drying process of a large honeycomb structure having a volume of 2 liters or more. It can be solved in a compatible manner. That is, the ratio of methyl cellulose (M) and hydroxypropyl methyl cellulose (H) is in the range of more than 50/50 and 90/10 or less, so that the fluidity of the clay during extrusion molding and the shape retention of the molded body are optimized. This is because the problem of turning over the outer peripheral wall, deformation of the molded body, and drying cracks, which has been difficult to solve in the past, can be solved at the same time because the thermal gelation strength can be secured.
In the present invention, the ratio of methyl cellulose (M) of 5 Pa · s or less at 2% aqueous solution viscosity (20 ° C.) to hydroxypropyl methyl cellulose (H) of 20 Pa · s or more at 2% aqueous solution viscosity (20 ° C.) is 50/50. It is important that the range is more than 90/10. This is because when the mass ratio (M / H) of both is 50/50 or less, that is, when the compounding ratio of hydroxypropylmethylcellulose (H) increases, the thermal gelation strength decreases and cracking occurs due to drying after molding. Because there is. On the other hand, when the mass ratio (M / H) of both exceeds 90/10, the shape retention is lowered and the thermal gelation temperature is lowered due to methyl cellulose blended more than necessary. At about 30 ° C, part of the gelation of methylcellulose begins to occur, the fluidity of the clay becomes unstable, the outer peripheral wall surface becomes rough during extrusion, and the outer peripheral wall surface tends to turn and crack. This is because in the worst case, molding may not be possible. Therefore, the mass ratio (M / H) exceeds 50/50 and is not more than 90/10. The blending at this mass ratio is particularly optimal when manufacturing a large honeycomb structure having a volume of 2 liters or more. Here, the ratio of 2% aqueous solution viscosity (20 ° C.) of methyl cellulose (M) of 5 Pa · s or less and 2% aqueous solution viscosity (20 ° C.) of 20 kPa or more of hydroxypropyl methyl cellulose (H) is 52 from the above viewpoint. / 48 or more and 75/25 or less is preferable.
また、本発明において、望ましくは、メチルセルロース（Ｍ）とヒドロキシプロピルメチルセルロース（Ｈ）をコージェライト化原料１００質量部に対して総量で２〜１５質量部配合する。メチルセルロースとヒドロキシプロピルメチルセルロースがコージェライト化原料１００質量部に対して総量で２質量部未満であると、成形体の保形性が不足し変形が発生しやすくなるからである。一方、メチルセルロースとヒドロキシプロピルメチルセルロースがコージェライト化原料１００質量部に対して総量で１５質量部を超えると、杯土の流動性を損ない、押出成形時にハニカム成形体を押出難くなるからである。本発明において、上記、保形性と流動性を両立させる観点からメチルセルロース（Ｍ）とヒドロキシプロピルメチルセルロース（Ｈ）をコージェライト化原料１００質量部に対して総量で７質量部を超え１２質量部以下配合することがより好ましい。
尚、成形助剤としては、メチルセルロース及びヒドロキシプロピルメチルセルロースを配合することに加えて、公知の成形助剤である、ポリビニルアルコール等の有機バインダーや界面活性剤、潤滑剤等の中から、用途に合ったものを加えても良い。
In the present invention, preferably, methylcellulose (M) and hydroxypropylmethylcellulose (H) are blended in a total amount of 2 to 15 parts by mass with respect to 100 parts by mass of the cordierite forming raw material. This is because when the total amount of methylcellulose and hydroxypropylmethylcellulose is less than 2 parts by mass with respect to 100 parts by mass of the cordierite forming raw material, the shape retention of the molded product is insufficient and deformation tends to occur. On the other hand, if methylcellulose and hydroxypropylmethylcellulose exceed 15 parts by mass in total with respect to 100 parts by mass of the cordierite forming raw material, the fluidity of the clay is impaired and it becomes difficult to extrude the honeycomb formed body during extrusion molding. In the present invention, from the viewpoint of achieving both shape retention and fluidity, the total amount of methylcellulose (M) and hydroxypropylmethylcellulose (H) exceeds 7 parts by weight and less than 12 parts by weight with respect to 100 parts by weight of the cordierite forming raw material. It is more preferable to mix.
In addition to blending methylcellulose and hydroxypropylmethylcellulose as a molding aid, it is suitable for use from organic binders such as polyvinyl alcohol, surfactants, lubricants, etc., which are known molding aids. You can also add food.
そして、本発明の製造方法において、コージェライト質セラミックハニカム構造体の容積が２リットル以上であることが好ましい。容積が２リットル以上のような大型のハニカム構造体の押出成形及び乾燥工程において発生する、相反する性質である外周壁表面のめくれ、成形体の変形、及び乾燥クラックの問題を本発明を用いることにより両立して解決することができるからである。 In the production method of the present invention, the volume of the cordierite ceramic honeycomb structure is preferably 2 liters or more. Use of the present invention for problems of the outer wall surface turning, deformation of the molded body, and drying cracks, which are contradictory properties, which occur in the extrusion and drying process of a large honeycomb structure having a volume of 2 liters or more. This is because they can be solved in a more compatible manner.
以上詳細に説明のとおり、本発明のハニカム構造体の製造方法によれば、杯土の流動性が良好なため外周壁表面のめくれが発生しにくく、保形性が良好なため成形体の変形が発生しにくく、乾燥時に乾燥ワレの発生が少ないハニカム構造体を得ることができる。 As described above in detail, according to the method for manufacturing a honeycomb structure of the present invention, the fluidity of the clay is good, so that the surface of the outer peripheral wall is not easily turned over, and the shape retention is good. It is possible to obtain a honeycomb structure that is less likely to generate and causes little dry cracking during drying.
次に、本発明を実施の形態に基づき更に詳細に説明する。
図１に示すハニカム構造体１１を以下のようにして複数個作成した。
カオリン、タルク、シリカ、水酸化アルミニウム、アルミナなどの粉末を調整して、化学組成が質量％で、ＳｉＯ2 ：４８〜５２％、Ａｌ2Ｏ3：３３〜３７％、ＭｇＯ：１２〜１５％、を含むコージェライト質セラミックの原料とした。
そして、表１に示すように、成形助剤として各種粘度のメチルセルロース（Ｍ）及びヒドロキシプロピルメチルセルロース（Ｈ）の質量比（Ｍ／Ｈ）及び、コージェライト質セラミックスの原料１００質量部に対して添加するメチルセルロース（Ｍ）とヒドロキシプロピルメチルセルロース（Ｈ）の総量（質量部）を変えて配合し、造孔剤を添加し、乾式で十分混合した。次いで、規定量の水を注入して更に十分な混練を行い、押出成形可能な坏土を精製した。なお、メチルセルロース（Ｍ）及びヒドロキシプロピルメチルセルロース（Ｈ）の粘度は、２０℃における２％水溶液を東機産業製ＢＬ型粘度計で測定した。
Next, the present invention will be described in more detail based on embodiments.
A plurality of
Kaolin, talc, silica, aluminum hydroxide, to adjust the powder, such as alumina, a chemical composition by mass%, SiO 2: 48~52%, Al 2 O 3: 33~37%, MgO: 12~15% As a raw material for cordierite ceramics, including
And as shown in Table 1, it adds with respect to 100 mass parts of raw material of the cordierite ceramics and the mass ratio (M / H) of methylcellulose (M) and hydroxypropyl methylcellulose (H) of various viscosities as a molding aid. The total amount (parts by mass) of methyl cellulose (M) and hydroxypropyl methyl cellulose (H) to be mixed was changed, a pore-forming agent was added, and they were thoroughly mixed by a dry method. Next, a specified amount of water was injected and further sufficient kneading was performed to refine the extrudable clay. The viscosity of methylcellulose (M) and hydroxypropylmethylcellulose (H) was measured with a BL type viscometer manufactured by Toki Sangyo Co., Ltd. at a 2% aqueous solution at 20 ° C.
次に、公知の押出成形用金型を用いて坏土を連続的に押出成形して、焼成後に、外周径が１４３．８ｍｍ、長さ１５０ｍｍで、セル壁で囲まれる断面が四角形状を有し、セル壁厚が０．３ｍｍ以下、気孔率が６０％以上のハニカム構造体となるように成形体を作製した。そして、押出成形後に、外周壁の表面のめくれの有無を調べた。
次に、成形体をマイクロ波乾燥炉に入れ、マイクロ波乾燥した。そして、乾燥後、乾燥ワレの有無を調べた。また成形体の変形を調査する為、真円度を調査した。
Next, the clay is continuously extruded using a known extrusion mold, and after firing, the outer diameter is 143.8 mm, the length is 150 mm, and the section surrounded by the cell walls has a square shape. Then, a molded body was produced so as to obtain a honeycomb structure having a cell wall thickness of 0.3 mm or less and a porosity of 60% or more. And after extrusion molding, the presence or absence of the turning of the surface of an outer peripheral wall was investigated.
Next, the compact was placed in a microwave drying oven and microwave dried. And after drying, the presence or absence of dry cracking was investigated. In order to investigate the deformation of the molded body, the roundness was investigated.
そして、メチルセルロース（Ｍ）とヒドロキシプロピルメチルセルロース（Ｈ）の２％水溶液（２０℃）の各粘度、配合比（％）、メチルセルロース（Ｍ）とヒドロキシプロピルメチルセルロース（Ｈ）の総量のコージェライト化原料１００質量部に対する添加割合（質量部）と、成形時の外周壁表面のめくれ、乾燥時の乾燥ワレ及び成形体の変形の有無の関係を評価した。なお、成形時の外周壁表面のめくれは、１ロットあたりの発生率が０％であったものを（◎）、５％未満であったものを（○）、５〜１０％であったものを（△）、１０％超であったものを（×）として評価し、乾燥時の乾燥ワレは、１ロットあたりの発生率が０％であったものを（◎）、５％未満であったものを（○）、５〜１０％であったものを（△）、１０％超であったものを（×）として評価し、成形体の変形は、成形体の外周面で円周方向１２個所の直径を測定し、そのバラツキを示す真円度が０．２mm未満であったものを（◎）、０．２〜０．５mmであったものを（○）、０．５〜１．０mmであったものを（△）、１．０mm超であり実使用上において使用不可能であったものを（×）として評価した。その結果を表１に示す。表１の評価結果の項目で、成形時の外周壁表面のめくれは「めくれ」、乾燥時の乾燥ワレは「割れ」、成形体の変形は「変形」として示す。 And each viscosity of 2% aqueous solution (20 degreeC) of methylcellulose (M) and hydroxypropyl methylcellulose (H), a compounding ratio (%), the cordierite-forming raw material 100 of the total amount of methylcellulose (M) and hydroxypropylmethylcellulose (H) 100 The relationship between the addition ratio (parts by mass) relative to parts by mass, the turning of the outer peripheral wall surface during molding, the drying crack during drying, and the presence or absence of deformation of the molded body was evaluated. In addition, the turning of the outer peripheral wall surface at the time of molding was (◎) where the occurrence rate per lot was 0% (◯), less than 5% (○), 5-10% Was evaluated as (x) when it was over 10%, and the dry cracking during drying was (◎) less than 5% when the rate of occurrence per lot was 0%. Was evaluated as (◯), 5% to 10% (Δ), and more than 10% as (x), and the deformation of the molded body was caused in the circumferential direction on the outer peripheral surface of the molded body. The diameters at 12 locations were measured, and the roundness indicating the variation was less than 0.2 mm (◎), 0.2 to 0.5 mm (◯), 0.5 to 1 A value of 0.0 mm was evaluated as (Δ), and a value of more than 1.0 mm, which was not usable in actual use, was evaluated as (×). The results are shown in Table 1. In the items of the evaluation results in Table 1, turning of the outer peripheral wall surface during molding is shown as “turning”, drying cracking during drying is shown as “cracking”, and deformation of the molded product is shown as “deforming”.
表１に示すように、本発明例の坏土は、２％水溶液粘度（２０℃）で５Ｐａ・ｓ以下のメチルセルロース（Ｍ）と、２％水溶液粘度（２０℃）で２０Ｐａ・ｓ以上のヒドロキシプロピルメチルセルロース（Ｈ）を、その質量比（Ｍ／Ｈ）、５０／５０を越え９０／１０以下の範囲で配合しているので、成形時の表面のめくれ、乾燥時の乾燥ワレ、成形体の変形を少なくしてハニカム構造体を製造できることがわかる。
特に、発明例５〜８、１２〜１４、１６〜１９の坏土は、２％水溶液粘度（２０℃）で５Ｐａ・ｓ以下のメチルセルロース（Ｍ）と、２％水溶液粘度（２０℃）で２０Ｐａ・ｓ以上のヒドロキシプロピルメチルセルロース（Ｈ）を、その質量比（Ｍ／Ｈ）５２／４８以上７５／２５以下の範囲で配合し、さらに、メチルセルロース（Ｍ）とヒドロキシプロピルメチルセルロース（Ｈ）の総量をコージェライト化原料１００質量部に対して７質量部を超え１２質量部以下の範囲で添加しているので、成形時の外周壁表面のめくれ、乾燥時の乾燥ワレ、成形体の変形が少ない、良好なハニカム構造体を製造できることがわかる。
一方、比較例１〜１０に示すように、成形助剤が本発明の範囲を外れているために、成形時に外周壁表面のめくれや乾燥時の乾燥ワレ、成形体の変形のいずれかが生じ良好なハニカム構造体を製造することができなかった。
As shown in Table 1, the clay of the example of the present invention consists of 2% aqueous solution viscosity (20 ° C.) and 5 Pa · s or less methyl cellulose (M), and 2% aqueous solution viscosity (20 ° C.) and 20 Pa · s or more hydroxy. Since propylmethylcellulose (H) is blended in a mass ratio (M / H) exceeding 50/50 and 90/10 or less, the surface is turned over at the time of molding, the dry cracking at the time of drying, It can be seen that the honeycomb structure can be manufactured with less deformation.
In particular, the clays of Invention Examples 5 to 8, 12 to 14, and 16 to 19 are 2% aqueous solution viscosity (20 ° C.) and 5 Pa · s or less methyl cellulose (M), and 2% aqueous solution viscosity (20 ° C.) is 20 Pa. -The hydroxypropyl methylcellulose (H) of s or more is blended in the mass ratio (M / H) of 52/48 or more and 75/25 or less, and the total amount of methylcellulose (M) and hydroxypropylmethylcellulose (H) is determined. Because it is added in the range of more than 7 parts by weight and less than 12 parts by weight with respect to 100 parts by weight of the cordierite forming raw material, the outer peripheral wall surface is turned over at the time of molding, drying cracking at the time of drying, and deformation of the molded body is small. It can be seen that a good honeycomb structure can be manufactured.
On the other hand, as shown in Comparative Examples 1 to 10, since the molding aid is out of the scope of the present invention, any one of turning of the outer peripheral wall surface during molding, drying cracking during drying, and deformation of the molded product occurs. A good honeycomb structure could not be manufactured.
１１：ハニカム構造体
１１ａ：外周壁
１１ｂ：セル壁
１１ｃ：セル
11:
Claims (4)
The method for producing a cordierite ceramic honeycomb structure according to any one of claims 1 to 3, wherein the cordierite ceramic honeycomb structure has a volume of 2 liters or more.
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| JP2012213908A (en) * | 2011-03-31 | 2012-11-08 | Ngk Insulators Ltd | Method for manufacturing honeycomb structure body |
| CN111377723A (en) * | 2020-03-24 | 2020-07-07 | 洛阳中超新材料股份有限公司 | Low-cost environment-friendly corundum-mullite honeycomb ceramic heat accumulator and preparation method thereof |
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| JP2003306375A (en) * | 2002-04-15 | 2003-10-28 | Hitachi Metals Ltd | Manufacturing method of cordierite honeycomb structure |
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| JP2003306375A (en) * | 2002-04-15 | 2003-10-28 | Hitachi Metals Ltd | Manufacturing method of cordierite honeycomb structure |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2012213908A (en) * | 2011-03-31 | 2012-11-08 | Ngk Insulators Ltd | Method for manufacturing honeycomb structure body |
| CN111377723A (en) * | 2020-03-24 | 2020-07-07 | 洛阳中超新材料股份有限公司 | Low-cost environment-friendly corundum-mullite honeycomb ceramic heat accumulator and preparation method thereof |
| CN111377723B (en) * | 2020-03-24 | 2020-11-03 | 洛阳中超新材料股份有限公司 | Low-cost environment-friendly corundum-mullite honeycomb ceramic heat accumulator and preparation method thereof |
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