JP4640903B2

JP4640903B2 - Honeycomb structure and manufacturing method thereof

Info

Publication number: JP4640903B2
Application number: JP2001214537A
Authority: JP
Inventors: 文夫安部; 敏雄山田
Original assignee: NGK Insulators Ltd
Current assignee: NGK Insulators Ltd
Priority date: 2001-07-13
Filing date: 2001-07-13
Publication date: 2011-03-02
Anticipated expiration: 2021-07-13
Also published as: JP2003025316A

Description

【０００１】
【発明の属する技術分野】
本発明は、ハニカム構造体に関する。より詳しくは、異なる特性の複数の材料からなり、特定部位毎に異なる複数の機能を兼備するハニカム構造体であり、特に、排ガス浄化システム、熱交換器、固体電解質電池、音響波動冷却装置等の熱音響機関等に好適なハニカム構造体に関するものである。
【０００２】
【従来の技術】
従来、排ガス浄化手段については、
▲１▼ハニカム構造体の隔壁に触媒機能を有する金属を担持した触媒体を用いて、排ガス中の炭化水素、一酸化炭素、又は窒素酸化物等の成分を酸化還元反応により分解する排ガス浄化手段、
▲２▼ハニカム構造体の隔壁を多孔質材料により構成させ、隔壁により形成される貫通孔を、貫通する両端面で、所定の貫通孔については一方の端面で目封じし、残余の貫通孔については他方の端面で目封じした構造とすることにより、排ガス中の粒子状物質を、隔壁により捕集・除去する排ガス浄化手段、
▲３▼ハニカム構造体の隔壁にゼオライト、活性炭等からなる吸着層を設けて、排ガス中の炭化水素成分等を吸着・除去する排ガス浄化手段
等、種々の試みがなされている。
【０００３】
また、近年、排ガス規制強化等に伴い、より高い浄化性能が求められており、その要請に応じる試みの１つとして、上述した異なる排ガス浄化手段を組合わせた排ガス浄化システムが開発されている。
【０００４】
例えば、特開平７−２３２０８４号公報には、異なる隔壁厚さ、及びセル密度の円柱状のハニカム構造体と、中空円筒状のハニカム構造体とを、セラミックス接合材で接合したハニカム構造体が開示されている。
【０００５】
しかしながら、このハニカム構造体では、各ハニカム構造体を別々に、しかも両者の形状を精密に合致させて製造する必要があった。このため、製造工程が複雑になり、製造コストが高くなるとともに、両者の形状の不整合に起因する接合部の緩み、はずれ等を生じ易かった。
【０００６】
また、このハニカム構造体では、接合部に応力が集中し易く、工程間の輸送、触媒や吸着材の付与、キャニング又は実使用等の際における機械的衝撃及び熱的衝撃等により、接合部の緩み、はずれ等を生じ易いという問題があった。
【０００７】
一方、ＷＯ０１／０４４６６公報には、触媒体とフィルターが直接一体化されているハニカム構造体が開示されている。
【０００８】
しかしながら、このハニカム構造体では、従来、セラミックス質のハニカム構造体について、異なる特性の材料からなるものを同時に一体的に製造する技術が開発されていなかったこともあり、触媒体とフィルターとで、求められる性能が大きく異なるにも拘らず、ハニカム構造体全体で、同一の特性を有する材料により構成されていたのが現状であった。
【０００９】
即ち、このハニカム構造体では、触媒体及びフィルターとして求められる性能に応じて、最適な材料により構成するといった点は何ら考慮されておらず、触媒体とフィルターとしての機能を兼備させたにも拘わらず、触媒体、及びフィルターとして求められる本来の性能を充分に発揮できるものではなかった。
【００１０】
【発明が解決しようとする課題】
本発明は、上述の課題に鑑みてなされたものであり、各ハニカム部毎に要求に応じた異なる高い性能を発揮することができ、しかも、各ハニカム部の形状不整合や接合材の存在による局所的な応力の集中がなく、使用時等の際に信頼性の高いハニカム構造体を提供することを目的とする。
また、本発明は、このような優れた特性を有するハニカム構造体を、簡易且つ確実な行程により低コストで製造することができる製造方法を提供することを目的とする。
【００１１】
【課題を解決するための手段】
本発明の発明者は、上述の目的を達成すべく鋭意検討したところ、異なる機能を有する各ハニカム部毎に、求められる性能に応じて異なる特性の材料により構成するとともに、各ハニカム部を接合材を介さずに直接接合することにより、上述した問題を解決できることを見出し、本発明のハニカム構造体を完成した。
また、本発明の発明者は、焼成後の特性が異なる材料からなる複数の坏土を、同時に押出し成形することにより、このようなハニカム構造体を簡易且つ確実に製造できることを見出し、本発明の製造方法を完成した。
【００１２】
即ち、本発明によれば、複数の隔壁により、軸方向に、複数の貫通孔が形成されているハニカム構造体であって、該ハニカム構造体が、触媒体として機能する第二のハニカム部と、その内周側に配置する排ガスフィルターとして機能する第一のハニカム部により構成され、前記第一のハニカム部、及び前記第二のハニカム部が異なる特性の材料により構成されてなり、かつ該第一、及び第二の複数のハニカム部が、それぞれ直接接合して一体化されていることを特徴とするハニカム構造体が提供される。
【００１３】
本発明においては、該第一、及び第二の複数のハニカム部が、ハニカム構造体の中心軸を含む中央領域に設けられる、排ガスフィルターとして機能する第一のハニカム部と、中央領域を包囲して隣接する外周領域に設けられる、触媒体として機能する第二のハニカム部とにより構成されていることが好ましい。
【００１４】
また、本発明においては、複数のハニカム部を構成する材料が、気孔率、平均細孔径、又は吸水率の少なくとも１種の特性で相違することが好ましい。この際、複数のハニカム部を構成する材料は、気孔率が５〜８０％であることが好ましく、平均細孔径が０．５〜１００μｍであることが好ましく、吸水率が１〜９５％であることが好ましい。
【００１５】
また、本発明においては、更に、ハニカム構造体を、そのセル構造のうち、セル密度、隔壁厚さ、又は貫通孔における径方向の断面形状の少なくとも１種において異なる複数のハニカム部により構成することも好ましく、この際には、セル構造が相違する複数のハニカム部が、異なる特性の材料からなる複数のハニカム部に、実質的に対応して設けられていることが好ましい。
【００１６】
本発明においては、セル構造が相違する複数のハニカム部は、０．１５５〜３．１０１セル／ｍｍ²（１００〜２０００セル／平方インチ）のセル密度を有することが好ましく、２５〜５００μｍの隔壁厚さを有することが好ましい。
【００１７】
なお、本発明においては、複数のハニカム部を構成する材料として、コーディエライト、炭化珪素、窒化珪素、アルミナ、ムライト、リチウムアルミニウムシリケート、アルミニウムチタネート、及びジルコニアからなる群より選ばれた少なくとも１種を用いることができる。
【００１８】
また、本発明においては、触媒体としての性能を付与するのであれば、少なくとも一部のハニカム部の隔壁に、触媒能を有する金属を担持すればよく、吸着体としての性能を付与するのであれば、少なくとも一部のハニカム部の隔壁に、炭化水素吸着能を有する吸着層を設ければよく、含塵流体中に含まれる粒子状物質を捕集・除去するフィルターとしての性能を付与するのであれば、少なくとも一部のハニカム部を、濾過能を有する隔壁により構成させ、この濾過能を有する隔壁により形成される貫通孔を、貫通孔が貫通する両端面で所定の貫通孔については一方の端部を封じ、残余の貫通孔については他方の端部を封じて目封じすればよい。
【００１９】
他方、本発明によれば、セラミックス材料を主成分とする原料と、媒質とを混練して坏土を得、この坏土を押出し成形するハニカム構造体の製造方法であって、セラミックス材料を主成分とする原料として、焼成後の特性が異なる複数の原料を用い、この複数の原料を、それぞれ異なる混練機構で媒質と混練して、焼成後の特性が異なる複数の坏土を得、この複数の坏土を、それぞれ口金の異なる位置に導入した後、同時に押出し後、その外周側に触媒能を有する金属を担持し触媒体として機能する第二のハニカム部を形成し、その内周側に配置する排ガスフィルターとして機能する第一のハニカム部を形成することを特徴とするハニカム構造体の製造方法が提供される。
【００２０】
本発明の製造方法において、複数の坏土を、それぞれ口金の異なる位置に導入した後、同時に押出しする手段としては、複数の坏土を一体とした複合坏土を口金に導入して、複数の坏土を同時に押出しする方法が好ましい。
【００２１】
この際、複合坏土は、一の材料からなる一の坏土の周囲に、一の坏土とは焼成後の特性が異なる少なくとも１以上の他の坏土を配設してなるものが好ましい。
【００２２】
また、本発明の製造方法において、複数の坏土を、それぞれ口金の異なる位置に導入した後、同時に押出しする他の手段としては、複数の坏土を、それぞれ異なる押出し機構により、口金の異なる位置に導入した後、同時に押出し成形する方法も好ましい。
【００２３】
この際、押出し機構としてシリンジ式の押出し機構を用いてもよいが、スクリュー式の押出し機構とすることにより、セラミックス材料を主成分とする原料と媒質との混練、及び混練により得られる坏土の押出しを、一連の工程により連続的に行うことが好ましい。
【００２４】
また、本発明の製造方法においては、セラミックス材料を主成分とする原料が、気孔率、平均細孔径、又は吸水率の少なくとも１種から選ばれる焼成後の特性で相違することが好ましい。
【００２５】
また、口金として、セルブロックピッチ、スリット幅、又はセルブロックの押出し方向に対する垂直方向の断面形状の少なくとも１種が、異なる特性の坏土が導入される部位毎に、実質的に相違するものを用いることも好ましい。
【００２６】
【発明の実施の形態】
以下、本発明の実施の形態を、図面を参照しつつ具体的に説明する。
【００２７】
図１に示すように、本発明のハニカム構造体１は、複数の隔壁２により、軸方向に、複数の貫通孔３が形成されているものであり、ハニカム構造体１が、異なる特性の材料からなる複数のハニカム部１０、１１により構成され、かつこの複数のハニカム部１０、１１が、それぞれ直接接合して一体化されているものである。
【００２８】
これにより、各ハニカム部１０、１１が、求められる性能に応じて、異なる高い性能を発揮することができ、しかも、各ハニカム部１０、１１の形状不整合や接合材の存在による局所的な応力集中がなく、使用時等における信頼性を向上させることができる。以下、具体的に説明する。
【００２９】
本発明においては、複数のハニカム部１０、１１を構成する材料として、例えば、コーディエライト、金属シリコン、炭化珪素、窒化珪素、アルミナ、ムライト、リチウムアルミニウムシリケート、アルミニウムチタネート、及びジルコニアからなる群より選ばれた少なくとも１種を挙げることができる。
【００３０】
また、ハニカム部１０、１１を構成する材料の特性としては、例えば、気孔率、平均細孔径、吸水率、又は比熱等を挙げることができ、本発明においては、これらの特性の少なくとも１種を、各ハニカム部１０、１１で求められる性能に応じて、異なるものとすることが好ましい。
【００３１】
例えば、触媒体又は吸着体として用いられるハニカム部１０では、気孔率を２０〜４０％、平均細孔径を１〜８０μｍ、吸水率を１〜４０％とすることが好ましく、気孔率を２５〜３５％、平均細孔径を１〜６０μｍ、吸水率を４〜３５％とすることがより好ましい。
【００３２】
また、例えば、フィルターとして用いられるハニカム部１１では、気孔率を４０〜８０％、平均細孔径を５〜４５μｍとすることが好ましく、気孔率を４０〜７０％、平均細孔径を１０〜４０μｍとすることがより好ましい。
【００３３】
また、如何なる性能を付与するハニカム部１０、１１であっても、ハニカム構造体１の軽量化、及び強度を考慮すると、それぞれ、気孔率を５〜８０％、平均細孔径を０．５〜１００μｍ、吸水率を１〜９５％とすることが好ましく、それぞれ、気孔率を２５〜７０％、平均細孔径を１〜６０μｍ、吸水率を４〜９２％とすることがより好ましい。
【００３４】
本発明においては、各ハニカム部１０、１１毎に異なる材料により構成させることにより、各ハニカム部１０、１１の材料特性を異ならしめたものでもよく、同一の材料により各ハニカム部１０、１１を構成させながらも、材料特性を異ならしめたものでもよい。後者の場合としては、例えば、同一種類の材料で構成させながら、気孔率、細孔径等を異ならしめたものを挙げることができ、例えば、原料中に結晶成長助剤、造孔材等を添加することにより、このようなハニカム構造体とすることができる。
【００３５】
図２、図３に示すように、本発明のハニカム構造体１においては、更に、求められる各ハニカム部１２、１３の性能に応じて、そのセル構造のうち、セル密度、隔壁厚さ、又は貫通孔における径方向の断面形状等の少なくとも１種が異なる複数のハニカム部１２、１３により構成させることもできる。
【００３６】
例えば、触媒体又は吸着体として用いられるハニカム部では、それぞれ、セル密度を０．４６５〜３．１０１セル／ｍｍ²（３００〜２０００セル／平方インチ）、隔壁厚さを２５〜３００μｍ、貫通孔における径方向の断面形状を三角形、四角形、六角形、又は円形とすることが好ましく、それぞれセル密度を０．９３０〜３．１０１セル／ｍｍ²（６００〜２０００セル／平方インチ）、隔壁厚さを２５〜１００μｍとすることがより好ましい。
【００３７】
また、例えば、フィルターとして用いられるハニカム部では、それぞれ、セル密度を０．１５５〜０．６２０セル／ｍｍ²（１００〜４００セル／平方インチ）、隔壁厚さを１００〜５００μｍ、貫通孔における径方向の断面形状を三角形、四角形、又は六角形とすることが好ましく、それぞれ、セル密度を０．２３６〜０．４６５セル／ｍｍ²（１５０〜３００セル／平方インチ）、隔壁厚さを２００〜３００μｍ、貫通孔における径方向の断面形状を四角形とすることがより好ましい。
【００３８】
また、如何なる性能を付与するハニカム部であっても、ハニカム構造体１の軽量化、及び強度を考慮すると、それぞれ、セル密度を０．１５５〜３．１０１セル／ｍｍ²（１００〜２０００セル／平方インチ）、隔壁厚さを２５〜５００μｍとすることが好ましく、それぞれ、セル密度を０．２３６〜３．１０１セル／ｍｍ²（１５０〜２０００セル／平方インチ）、隔壁厚さを２５〜３００μｍとすることがより好ましい。また、貫通孔の径方向の断面形状としては、例えば、三角形、四角形、六角形、楕円形、又は円形等を挙げることができる。
【００３９】
図２に示すように、本発明においては、セル構造の異なる複数のハニカム部１２、１３は、必ずしも、異なる特性の材料からなる複数のハニカム部１０、１１に、対応して設ける必要はなく、セル構造の異なる複数のハニカム部１０、１１と、異なる特性の材料からなる複数のハニカム部１２、１３とを、それぞれ異なる部位で設けてもよい。
【００４０】
もっとも、各ハニカム部で求められる高い性能を発揮させるためには、図３に示すように、前述した異なる特性の材料からなる複数のハニカム部１０、１１に、実質的に対応させて、異なるセル構造の複数のハニカム部１２、１３を設けることが好ましい。
【００４１】
具体的には、異なる特性の材料からなる各ハニカム部１０、１１の境界と、異なるセル構造を設けた各ハニカム部１２、１３の境界との差が、１０セル以内であることが好ましく、７セル以内であることがより好ましく、５セル以内であることが更に好ましく、３セル以内であることが特に好ましい。
【００４２】
本発明のハニカム構造体１においては、異なる特性の材料からなる複数のハニカム部１０、１１をどのような位置に設けるかについては特に制限はなく、求められる設計、性能等に応じて、適宜適切な位置に設ければよい。
【００４３】
例えば、図１に示すように、異なる特性の材料からなる複数のハニカム部１０、１１を、ハニカム構造体の中心軸を含む中央領域に設けられる、異なる特性の一の材料からなる第一のハニカム部１１と、中央領域を包囲して隣接する外周領域に設けられる、異なる特性の他の材料からなる第二のハニカム部１０とにより構成させたものを挙げることができる。
【００４４】
また、図４に示すように、他の実施形態としては、異なる特性の材料からなる複数のハニカム部１０、１１を、ハニカム構造体１の中心軸と平行に略均等の間隔で位置する複数の円筒形状からなる領域に設けられる、異なる特性の一の材料からなる第一のハニカム部１１と、この複数の円筒形状からなる領域を包囲して隣接する外周領域に設けられる、異なる特性の他の材料からなる第二のハニカム部１０とにより構成させたものを挙げることができる。
【００４５】
更に他の実施形態としては、図５に示すように、ハニカム構造体１を軸方向に２分割した場合の、一方の領域に設けられる異なる特性の一の材料からなる第一のハニカム部１１と、他方の領域に設けられる異なる特性の他の材料からなる第二のハニカム部１０とにより構成されるもの；図６に示すように、ハニカム構造体１を軸方向に４分割した場合の、対角に位置する一対の領域にそれぞれ設けられる、異なる特性の一の材料からなる第一のハニカム部１１と、異なる特性の他の材料からなる第二のハニカム部１０とにより構成されるもの等を挙げることができる。
【００４６】
図１、４〜６に示すように、本発明のハニカム構造体１は、上述した複数のハニカム部１０、１１が、それぞれ直接接合して一体化されているものである。
【００４７】
これにより、例えば、各ハニカム部１０、１１を同質の主結晶からなるものとすれば、接合部に集中する応力を低減して耐衝撃性、耐熱衝撃性等を向上させることができる。また、別々に製造したものを、寸法を合わせて接合するという必要がなく、製造工程を簡素化することができる。更に、接合部を要しない分、ハニカム構造体の有効断面積を増大させることができる。
【００４８】
なお、複数のハニカム部１０、１１を、直接接合して一体化する方法については、後述する本発明の製造方法で述べることとする。
【００４９】
本発明におけるハニカム構造体１では、求められる性能に応じて、上述した各ハニカム部１０、１１に種々の付加物を設けることが好ましい。
【００５０】
例えば、触媒担体としての性能を付与する場合であれば、その性能を付与するハニカム部１０、１１の隔壁３に、触媒能を有する金属を担持することが好ましく、この際、触媒能を有する金属しては、例えば、Ｐｔ、Ｐｄ、Ｒｈ等を挙げることができる。
【００５１】
同様に、炭化水素等の吸着体としての性能を付与する場合には、その性能を付与するハニカム部１０、１１の隔壁３に、炭化水素等を吸着する吸着層を設けることが好ましい。この際、吸着層としては、例えば、ゼオライト、活性炭等からなる層を挙げることができ、中でも、耐熱性の点でゼオライトからなる層が好ましい。また、ゼオライトとしては、天然品、合成品何れのものでも用いることができるが、Ｓｉ／Ａｌモル比が、４０以上のものが好ましく、例えば、ＺＳＭ−５、ＵＳＹ、β−ゼオライト、モルデナイト、シリカライト、メタロシリケート等を好適に挙げることができる。なお、これらゼオライトは、種々の分子サイズの炭化水素等を吸着するためには、二種以上組合わせて用いることが好ましい。
【００５２】
更に、フィルターとしての性能を付与する場合には、その性能を付与するハニカム部１０、１１の隔壁３を、前述した特性を有する材料からなる濾過能を有するものとし、この濾過能を有する隔壁により形成される貫通孔３を、貫通孔３が貫通する両端面で、所定の貫通孔については一方の端面で目封じし、残余の貫通孔については他方の端面で目封じしたものが好ましい。これにより、含塵流体中に含まれる粒子状物質を捕集・除去するフィルターとして用いることができる。
【００５３】
なお、本発明における各ハニカム部１０、１１は、これらの性能に限らず、その用途に応じて種々の性能を付与すればよいことは言うまでもない。
【００５４】
また、本発明のハニカム構造体１においては、構造体自体の形状については特に制限はなく、設計等に応じて、三角形、長方形、正方形、菱形、台形等の多角形、楕円、円形、レーストラック形状、半楕円形、又は半円形等の形状を適用することができる。
【００５５】
次に、本発明のハニカム構造体の製造方法について説明する。
本発明のハニカム構造体の製造方法は、セラミックス材料を主成分とする原料として、焼成後の特性が異なる複数の材料からなるものを用い、この複数の材料を、それぞれ異なる混練機構により、媒質と混練して複数の坏土を得、この複数の坏土を、それぞれ口金の異なる位置に導入した後、複数の坏土を同時に押出しするものである。
【００５６】
このような本発明の製造方法によれば、焼成後の特性が異なる各ハニカム部を直接接合して一体化した本発明のハニカム構造体を、簡易且つ確実な工程により低コストで製造することができる。以下、具体的に説明する。
【００５７】
まず、本発明の製造方法では、セラミックス材料を主成分とする原料として、焼成後の特性が異なる複数の原料を用いる。
【００５８】
セラミックス材料を主成分とする原料としては、例えば、金属シリコン、炭化珪素、チタン、ジルコニウム、炭化ホウ素、炭化チタン、炭化ジルコニウム、窒化ケイ素、窒化ホウ素、窒化アルミニウム、酸化アルミニウム、酸化ジルコニウム、ムライト、コーディエライト化原料、チタン酸アルミニウム、サイアロン、カオリン、タルク、水酸化アルミニウム、溶融シリカ、及び石英よりなる群から選ばれる少なくとも一の材料を主成分として含むものを挙げることができ、焼結後に、求められる性能に応じて、適宜選択すればよい。また、添加物として、結晶成長助剤、造孔材等の他の材料を更に含有させることにより、焼結後に、求められる性能に対応する原料としてもよい。なお、添加物として、分散剤、結合剤等を含有させてもよいことは言うまでもない。
【００５９】
セラミックス材料を主成分とする原料の焼成後の特性としては、例えば、気孔率、平均細孔径、吸水率、又は比熱等を挙げることができ、本発明では、これら特性の少なくとも１種で相違する原料を用いることが好ましい。
これらの特性における所望の範囲は、本発明のハニカム構造体で示したものと同様であり、焼結後そのような特性が得られるように、原料を調製しておくことが好ましい。
【００６０】
なお、触媒体、吸着体又はフィルターとして用いる部分の原料としては、コーディエライトやＳｉＣ等を主成分とするものを挙げることができる。
【００６１】
本発明の製造方法では、次に、焼成後の特性が異なる材料を、それぞれ異なる混練機構により、媒質等と混練して複数の坏土を得る。
【００６２】
本発明においては、混練機構について特に制限はなく、例えば、真空土練機を用いて混練してもよいが、後述するスクリュー式の押出し機構を用いて、混練工程と押出し工程を一連の工程で連続的に行うことが生産性向上の点から好ましい。
【００６３】
また、本発明においては、媒質について特に制限はなく、前述した原料等に応じて適宜好ましいものを用いればよい。
【００６４】
本発明の製造方法では、次に、得られた焼成後の特性が異なる複数の坏土を、それぞれ口金の異なる位置に導入した後、複数の坏土を同時に押出して成形する。
【００６５】
得られた焼成後の特性が異なる複数の坏土を、それぞれ口金の異なる位置に導入した後、同時に押出しする手段としては、焼成後の特性が異なる複数の坏土を一体化した複合坏土を作製し、この複合坏土を、押出し成形する方法を挙げることができる。この際、この複合坏土は、例えば、図７に示すように、一の材料からなる一の坏土２０の周囲に、一の坏土２０とは焼成後の特性が異なる少なくとも１以上の他の坏土２１を、配設して一体とすることにより得ることができる。このような複合坏土２２では、１つのシリンジ式の押出し機構で、簡単に異なる特性の材料からなるハニカム部を直接接合したハニカム構造体を得ることができる。
【００６６】
なお、前述した中央領域に設けられる第一のハニカム部と、外周領域に設けられる第二のハニカム部とを、ハニカム構造体の中心軸を略同心とする位置で設ける場合には、一の材料からなる一の坏土２０と、その周囲に設けられる一の坏土とは焼成後の特性が異なる材料からなる他の坏土２１とを、略同心となる位置で設ければよい。
【００６７】
また、本発明では、押出し成形によりハニカム構造体を製造するため、前述した複合坏土２２は、押出し方向に対する垂直の方向に、焼成後の特性が異なる材料からなる各坏土２０、２１が、積層されていることが好ましい。
また、押出し成形の際の成形性を向上させるためには、焼成後の特性が異なる複数の坏土２０、２１間の間隙を小さくして密接に接合させておくことが好ましい。
【００６８】
得られた異なる特性の材料からなる複数の坏土を、それぞれ口金の異なる位置に導入した後、同時に押出しする他の手段としては、焼成後の特性が異なる複数の坏土を、それぞれ異なる押出し機構により、口金の異なる位置に導入し、同時に押出しする方法を挙げることができる。
【００６９】
具体的には、図８（ａ）（ｂ）に示すように、押出し機構として、複数のシリンジ式の押出し機構１８、１９を用い、焼成後の特性が異なる複数の坏土２０、２１を、各シリンジ式の押出し機構１８、１９内に投入し、各押出し機構１８、１９における押出し工程を同期させて行うことにより、各坏土２０、２１を同時に押出しする方法、又は図９（ａ）（ｂ）に示すように、押出し機構として、複数のスクリュー式の押出し機構１６、１７を用い、各押出し機構１６、１７における原料と媒質との混練の工程、及び混練により得られる坏土の押出しの工程を同期させて行うことにより、各坏土２０、２１を同時に押出しする方法を挙げることができる。
【００７０】
中でも、原料と媒質との混練、及び混練により得られる坏土の押出しを連続的に行うことができ、生産性を極めて高くすることができる点で、スクリュー式の押出し機構１６、１７を用いる後者の方法が好ましい。
【００７１】
また、押出し機構の配置としては、例えば、図１０（ａ）（ｂ）に示すように、口金２５における焼成後の特性が異なる各坏土を導入する各部位２６、２７毎に対応して、各押出し機構１６、１７を配設したものを挙げることができる。もっとも、図９（ａ）（ｂ）に示すように、少なくとも一の押出し機構１７に、押出し機構１７と口金２５の特定の部位とを連通し、口金２５の特定の部位に坏土を導入するガイド部２８を設け、各押出し機構１６、１７を設計等に応じて自由に配設することも好ましい。なお、このガイド部２８を設けた押出し機構１７では、押出し機構自体の設計も極めて簡易なものとすることができる。
【００７２】
本発明においては、用いる口金の形状及び構造について特に制限はないが、例えば、セル密度、隔壁厚さ、又は貫通孔の径方向における断面形状等のセル構造の異なる複数のハニカム部を設ける場合には、求められるセル構造に応じて、セルブロックピッチ、スリット幅、又はセルブロックの押出し方向に対する垂直方向の断面形状の少なくとも１種を相違させることが好ましい。
【００７３】
また、異なる特性の材料からなる複数のハニカム部に略対応して、セル構造の異なる複数のハニカム部を設ける場合には、実質的に異なる特性の坏土が導入される部位毎にセル構造を相違させることが好ましい。
【００７４】
具体的には、焼成後の特性が異なる坏土が導入される口金の各部位の境界と、異なる形状及び構造とした口金の各部位の境界との差が、１０セル以内であることが好ましく、７セル以内であることがより好ましく、５セル以内であることが更に好ましく、３セル以内であることが特に好ましい。
【００７５】
本発明の製造方法では、通常、得られたハニカム構造の成形体を焼成することにより最終製品とする。焼成は、通常、マイクロ波及び／又は熱風等により成形体を乾燥した後、焼成することが好ましい。
【００７６】
【実施例】
以下、本発明を実施例により具体的に説明するが、本発明はこれら実施例に何ら限定されるものではない。
なお、各実施例及び比較例で得られたハニカム構造体の評価は、以下の方法等により行った。
【００７７】
（評価方法）
１．平均細孔径
マイクロメリティック社製の水銀圧入式ポロシメーターで測定した。
２．気孔率
ハニカム構造体の構成材料の真比重と、全細孔容積から計算で求めた。また、細孔容積は、マイクロメリティック社製の水銀圧入式ポロシメーターで測定した。
３．吸水率
ＪＩＳＲ２２０５記載の方法により測定した。
【００７８】
（実施例及び比較例）
実施例１
まず、セラミックス原料として、それぞれ焼成後の特性が異なるコーディエライト化材料からなる第一のセラミックス原料と、第二のセラミックス原料とをそれぞれ調製した。
【００７９】
次いで、各セラミックス原料を、媒質として用いた水とともに、それぞれ異なる真空土練機に投入して、各セラミックス原料と水とを混練、成形し、直径１５０ｍｍの円柱形状を有する第一のセラミックス原料からなる坏土と、幅４７５ｍｍ、厚さ４０ｍｍの平板状を有する第二のセラミックス原料からなる坏土を得た。
【００８０】
次いで、円柱形状を有する第一のセラミックス原料からなる坏土の周囲に、平板状を有する第二のセラミックス原料からなる坏土を巻き付けて一体化した複合坏土を作製した。
【００８１】
次いで、得られた円柱状の複合坏土を、直径１２０ｍｍの中央部とその外周部で、セル構造の異なる口金を配設したラム式押出成形機に投入し、押出し成形を行った。
【００８２】
次いで、得られた成形体を熱風及びマイクロ波により乾燥後、第一のセラミックス原料からなるハニカム部の貫通孔を、貫通する両端面で互い違いに目封じし、焼成した後、第二のセラミックス原料からなるハニカム部の隔壁にＰｔを主成分とする触媒を担持して、長さ２０３ｍｍ、直径１９０ｍｍの円柱状であり、第一のセラミックス原料からなるハニカム部が、ハニカム構造体と同心の直径１２０ｍｍの円柱形状領域で設けられているハニカム構造体を得た。
【００８３】
得られたハニカム構造体の特性を調査したところ、第一のセラミックス原料からなるハニカム部では、平均細孔径３０μｍ、吸水率９１％、気孔率７０％、隔壁厚さ０．２５ｍｍ、セル密度０．４６５セル／ｍｍ²（３００セル／平方インチ）、貫通孔の径方向の断面形状が四角形であり、第二のセラミックス原料からなるハニカム部では、平均細孔径５μｍ、吸水率１７％、気孔率３０％、隔壁厚さ０．１ｍｍ、セル密度０．９３０セル／ｍｍ²（６００セル／平方インチ）、貫通孔の径方向の断面形状四角形であった。
【００８４】
また、図１１に示すように、このハニカム構造体１をメタルケース４０に把持し、２４００ｃｃのディーゼルエンジンの排気管４１を第一のセラミックス原料からなる第一のハニカム部１１に対応させて配設し、排ガス浄化装置を作製した。
【００８５】
排ガスを、排気管４１の外壁と、メタルケースの内壁で形成される排ガス導入路３９から導入して、第二のセラミックス原料からなりＮＯをＮＯ₂に変換する触媒体として機能する第二のハニカム部１０と、第一のセラミックス原料からなり粒子状物質を捕集・除去するフィルターとして機能する第一のハニカム部１１とを順に経由させて排ガスを浄化したところ、優れた排ガス浄化性能が認められた。また、試験後のハニカム構造体について、損傷、変形等を確認したところ、両ハニカム部の接合部を含め、剥離、亀裂等の損傷、及び貫通孔の変形等は全く認められなかった。なお、図１１中の矢印は、排ガスの進行方向を示す。
【００８６】
実施例２
まず、セラミックス原料として、それぞれ焼成後の特性が異なる炭化珪素材料からなる第一のセラミックス原料と第二のセラミックス原料とをそれぞれ調製した。
【００８７】
次いで、第一のセラミックス原料を押出しする一のスクリュー式押出し機構が、口金の入口端面の中心点と同心の直径９０ｍｍの中央部に対応して設けられ、第二のセラミックス原料を押出しする他のスクリュー式押出し機構が、前述した口金の中央部と同心の外周部に連通するガイド部を有する押出し成形装置を用い、各セラミックス原料を、媒質とともに、それぞれ異なるスクリュー式押出し機構に投入して、混練、及び得られる各坏土の押出し成形を各押出し機構で同期させて行い、ハニカム構造の成形体を作製した。この際、口金としては、中央部と外周部でセル構造の異なるものを用いた。
【００８８】
次いで、得られた成形体をマイクロ波により乾燥後、第一のセラミックス原料からなるハニカム部の貫通孔を、貫通する両端面で互い違いに目封じした後、焼成した。その後、第二のセラミックス原料からなるハニカム部の隔壁にＰｔを主成分とする触媒を担持して、第一のセラミックス原料からなるハニカム部が、ハニカム構造体と同心の直径９０ｍｍの円柱形状領域で設けられている長さ１５２ｍｍ、直径１４４ｍｍの円柱状のハニカム構造体を得た。
【００８９】
得られたハニカム構造体の特性を調査したところ、第一のセラミックス原料からなるハニカム部では、平均細孔径１０μｍ、気孔率４５％、吸水率２７％、隔壁厚さ０．３ｍｍ、セル密度０．３１０セル／ｍｍ²（２００セル／平方インチ）、貫通孔の径方向の断面形状四角形であり、第二のセラミックス原料からなるハニカム部では、平均細孔径４μｍ、気孔率２０％、吸水率９％、隔壁厚さ０．１５ｍｍ、セル密度０．６２０セル／ｍｍ²（４００セル／平方インチ）、貫通孔の径方向の断面形状は六角形であった。
【００９０】
また、図１１に示すように、このハニカム構造体１を、メタルケース４０に把持し、２４００ｃｃのディーゼルエンジンの排気管４１を第一のセラミックス原料からなる第一のハニカム部１１に対応させて配設し、排ガス浄化装置を作製した。
【００９１】
排ガスを、排気管４１の外壁と、メタルケースの内壁で形成される排ガス導入路３９から導入して、第二のセラミックス原料からなりＮＯをＮＯ₂に変換する触媒体として機能する第二のハニカム部１０と、第一のセラミックス原料からなり粒子状物質を捕集・除去するフィルターとして機能する第一のハニカム部１１とを順に経由させて排ガスを浄化したところ、優れた排ガス浄化性能が認められた。また、試験後のハニカム構造体について、損傷、変形等を確認したところ、両ハニカム部の接合部を含め、剥離、亀裂等の損傷、及び貫通孔の変形等は全く認められなかった。なお、図１１中の矢印は、排ガスの進行方向を示す。
【００９２】
実施例３
まず、セラミックス原料として、それぞれ焼成後の特性が異なるコーディエライト化材料からなる第一のセラミックス原料と、第二のセラミックス原料とをそれぞれ調製した。
【００９３】
次いで、第一のセラミックス原料を押出しする一のスクリュー式の押出し機構を口金の中央部に対応して配設し、第二のセラミックス原料を押出しする複数のスクリューを有する他のスクリュー式押出し機構を、一のスクリュー式押出し機構の外周部に配設した押出し成形装置を用い、各セラミックス原料を、それぞれ異なるスクリュー式押出し機構に投入して、各セラミックス原料の混練、及び得られる各坏土の押出しを、各押出し機構で同期させて行いハニカム構造の成形体を作製した。この際、口金としては、中央部と外周部でセル構造の異なるものを用いた。
【００９４】
次いで、得られた成形体を乾燥、焼成した後、第二のセラミックス原料からなるハニカム部の隔壁には、Ｐｔ及びＰｄを主成分とする触媒を担持し、第一のセラミックス原料からなるハニカム部の隔壁には、ゼオライトＺＳＭ−５（ＴｈｅＰＱ（株）社製）を主成分とする吸着層を設け、第一のセラミックス原料からなるハニカム部が、ハニカム構造体と同心の直径４５ｍｍの円柱形状領域で設けられている長さ１５２ｍｍ、直径１４４ｍｍの円柱状のハニカム構造体を得た。
【００９５】
得られたハニカム構造体の特性を調査したところ、第一のセラミックス原料からなるハニカム部では、平均細孔径３μｍ、吸水率１０％、気孔率２０％、隔壁厚さ１５０μｍ、０．６２０セル／ｍｍ²（セル密度４００セル／平方インチ）、貫通孔の径方向の断面形状三角形であり、第二のセラミックス原料からなるハニカム部では、平均細孔径７μｍ、吸水率２２％、気孔率３５％、隔壁厚さ１００μｍ、セル密度０．４６５セル／ｍｍ²（３００セル／平方インチ）、貫通孔の径方向の断面形状が六角形であった。
【００９６】
また、このハニカム構造体を、メタルケースに把持し、３０００ｃｃのガソリンエンジンの排気管を、ハニカム構造体の一の端面に対応して配設し、排ガス浄化装置を作製した。
【００９７】
排ガスを、第二のセラミックス原料からなりＨＣ、ＣＯ、ＮＯxを酸化還元する三元触媒体として機能する第二のハニカム部と、第一のセラミックス原料からなり炭化水素成分を吸着する吸着体として機能する第一のハニカム部とに導入して、排ガスを浄化したところ、優れた排ガス浄化性能が認められた。また、試験後のハニカム構造体について、損傷、変形等を確認したところ、両ハニカム部の接合部を含め、剥離、亀裂等の損傷、及び貫通孔の変形等は全く認められなかった。
【００９８】
比較例１
セラミックス原料として、焼成後の特性が同一の一種類のコーディエライト化材料からなる原料を用いたこと、及び口金として、全体に、同一のセル構造を有するものを用いたこと以外は実施例１と同様にして、長さ２０３ｍｍ、直径１９０ｍｍの円柱状のハニカム構造体を得た。
【００９９】
得られたハニカム構造体の特性を調査したところ、ハニカム構造体全体で、平均細孔径７μｍ、吸水率２２％、気孔率３５％、隔壁厚さ０．２５ｍｍ、セル密度０．４６５セル／ｍｍ²（３００セル／平方インチ）、貫通孔の径方向の断面形状が四角形であった。
【０１００】
また、図１１に示すように、このハニカム構造体１をメタルケース４０に把持し、２４００ｃｃのディーゼルエンジンの排気管４１を第一のセラミックス原料からなる第一のハニカム部１１に対応させて装着し、排ガス浄化装置を作製した。
【０１０１】
排ガスを、排気管４１の外壁と、メタルケースの内壁で形成される排ガス導入路３９から導入して、ＮＯをＮＯ₂に変換する触媒体として機能させた第二のハニカム部１０と、粒子状物質を捕集・除去するフィルターとして機能させた第一のハニカム部１１とを順に経由させて排ガスを浄化したところ、フィルターとして機能させた第一のハニカム部１１の圧損が、実施例１のハニカム構造体に比べ３倍以上大きくなり、排ガス浄化装置として充分機能しなかった。
なお、図１１中の矢印は、排ガスの進行方向を示す。
【０１０２】
【発明の効果】
以上説明したように、本発明によれば、各ハニカム部毎に要求に応じた異なる高い性能を発揮することができ、しかも、各ハニカム部の形状不整合や接合材の存在による局所的な応力集中がなく、使用時等の信頼性の高い、特に、排ガス浄化システム、熱交換器、固体電解質電池、音響波動冷却装置等の熱音響機関等に好適なハニカム構造体を提供することができる。
また、本発明は、このような優れた特性を有するハニカム構造体を、簡易且つ確実な行程により低コストで製造することができる製造方法を提供することができる。
【図面の簡単な説明】
【図１】本発明のハニカム構造体における一の実施形態を模式的に示す斜視図である。
【図２】本発明のハニカム構造体において、異なる特性の材料からなる複数のハニカム部と、セル構造の異なるハニカム部との配置関係の一例を模式的に示す平面図である。
【図３】本発明のハニカム構造体において、異なる特性の材料からなる複数のハニカム部と、セル構造の異なるハニカム部との配置関係の他の例を模式的に示す平面図である。
【図４】本発明のハニカム構造体における他の実施形態を模式的に示す斜視図である。
【図５】本発明のハニカム構造体における更に他の実施形態を模式的に示す斜視図である。
【図６】本発明のハニカム構造体における更に他の実施形態を模式的に示す斜視図である。
【図７】本発明のハニカム構造体の製造方法において、複合坏土を作製する方法の一例を模式的に示す工程図である。
【図８】（ａ）は、本発明のハニカム構造体の製造方法において用いられる押出し機構の一例を模式的に示す一部断面図であり、（ｂ）は、（ａ）のガイド部の配置を示すＡの位置での一部断面図である。
【図９】（ａ）は、本発明のハニカム構造体の製造方法において用いられる押出し機構の他の例を模式的に示す一部断面図であり、（ｂ）は、（ａ）のガイド部の配置を示すＢの位置での一部断面図である。
【図１０】（ａ）は、本発明のハニカム構造体の製造方法において用いられる押出し機構の更に他の例を模式的に示す一部断面図であり、（ｂ）は、（ａ）のガイド部の配置を示すＣの位置での一部断面図である。
【図１１】本発明の実施例又は比較例におけるハニカム構造体を、ディーゼルエンジンの排気管に装着した排ガス浄化装置を示す半断面図である。
【符号の説明】
１…ハニカム構造体、２…隔壁、３…貫通孔、１０、１１…異なる特性の材料からなるハニカム部（１０…第二のハニカム部、１１…第一のハニカム部）、１２、１３…セル構造の異なるハニカム部、１６、１７…押出し機構（スクリュー式押出し機構）、１６ａ、１７ａ…スクリュー、１８、１９…押出し機構（シリンジ式押出し機構）、１８ａ、１９ａ…ピストン、２０…一の坏土、２１…他の坏土、２５…口金、２６、２７…口金の各坏土を導入する部位、２８…ガイド部、３１…ハニカム構造体（焼成前）、３９…排ガス導入路、４０…メタルケース、４１…排気管。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a honeycomb structure. More specifically, it is a honeycomb structure made of a plurality of materials having different characteristics and having a plurality of different functions for each specific part, and in particular, an exhaust gas purification system, a heat exchanger, a solid electrolyte battery, an acoustic wave cooling device, etc. The present invention relates to a honeycomb structure suitable for a thermoacoustic engine or the like.
[0002]
[Prior art]
Conventionally, regarding exhaust gas purification means,
(1) Exhaust gas purification means for decomposing components such as hydrocarbons, carbon monoxide or nitrogen oxides in exhaust gas by oxidation-reduction reaction using a catalyst body carrying a metal having a catalytic function on the partition walls of the honeycomb structure ,
(2) The partition walls of the honeycomb structure are made of a porous material, and the through holes formed by the partition walls are plugged at the both end surfaces that pass through, and one end surface of the predetermined through holes, and the remaining through holes Is an exhaust gas purification means for collecting and removing particulate matter in the exhaust gas by a partition wall by having a structure sealed at the other end face,
(3) Exhaust gas purification means for adsorbing and removing hydrocarbon components in exhaust gas by providing an adsorption layer made of zeolite, activated carbon, etc. on the partition walls of the honeycomb structure
Various attempts have been made.
[0003]
In recent years, with higher exhaust gas regulations and the like, higher purification performance has been demanded, and as one of the attempts to meet the demand, exhaust gas purification systems combining the different exhaust gas purification means described above have been developed.
[0004]
For example, Japanese Laid-Open Patent Publication No. 7-232084 discloses a honeycomb structure in which a columnar honeycomb structure having different partition wall thicknesses and cell densities and a hollow cylindrical honeycomb structure are bonded with a ceramic bonding material. Has been.
[0005]
However, in this honeycomb structure, it has been necessary to manufacture each honeycomb structure separately and precisely matching the shapes of both. For this reason, the manufacturing process is complicated, the manufacturing cost is increased, and the joints are liable to be loosened or disconnected due to the mismatch of the shapes.
[0006]
Further, in this honeycomb structure, stress tends to concentrate on the joint, and mechanical joint and thermal shock at the time of transportation between processes, application of a catalyst and an adsorbent, canning or actual use, etc. There has been a problem that loosening and slipping are likely to occur.
[0007]
On the other hand, WO01 / 04466 discloses a honeycomb structure in which a catalyst body and a filter are directly integrated.
[0008]
However, in this honeycomb structure, conventionally, a technology for manufacturing a ceramic honeycomb structure made of materials having different characteristics at the same time has not been developed. The present situation is that the entire honeycomb structure is made of a material having the same characteristics even though the required performance is greatly different.
[0009]
That is, in this honeycomb structure, no consideration is given to the constitution of an optimum material according to the performance required for the catalyst body and the filter, and the honeycomb structure has both functions as the catalyst body and the filter. However, the original performance required as a catalyst body and a filter could not be fully exhibited.
[0010]
[Problems to be solved by the invention]
The present invention has been made in view of the above-mentioned problems, and can exhibit different high performances according to requirements for each honeycomb portion, and further, due to the shape mismatch of each honeycomb portion and the presence of a bonding material. An object of the present invention is to provide a honeycomb structure having no local stress concentration and having high reliability in use.
Another object of the present invention is to provide a manufacturing method capable of manufacturing a honeycomb structure having such excellent characteristics at a low cost by a simple and reliable process.
[0011]
[Means for Solving the Problems]
The inventor of the present invention diligently studied to achieve the above-described object. As a result, each honeycomb part having different functions is made of a material having different characteristics depending on the required performance, and each honeycomb part is bonded to a bonding material. It has been found that the above-mentioned problems can be solved by directly joining without going through, and the honeycomb structure of the present invention has been completed.
Further, the inventor of the present invention has found that such a honeycomb structure can be easily and reliably manufactured by simultaneously extruding a plurality of clays made of materials having different characteristics after firing. Completed the manufacturing method.
[0012]
That is, according to the present invention, a honeycomb structure in which a plurality of through holes are formed in the axial direction by a plurality of partition walls, the honeycomb structure having a second honeycomb portion that functions as a catalyst body and The first honeycomb portion functioning as an exhaust gas filter disposed on the inner peripheral side thereof, The first honeycomb part and the second honeycomb part are made of materials having different characteristics, In addition, a honeycomb structure is provided in which the first and second plurality of honeycomb portions are directly joined and integrated.
[0013]
In the present invention, The first and second A plurality of honeycomb portions are provided in a central region including the central axis of the honeycomb structure. Functions as an exhaust gas filter Provided in an outer peripheral region adjacent to the first honeycomb portion and surrounding the central region; Functions as a catalyst body It is preferable that the second honeycomb portion is formed.
[0014]
In the present invention, it is preferable that the materials constituting the plurality of honeycomb portions differ in at least one characteristic of porosity, average pore diameter, or water absorption. At this time, the material constituting the plurality of honeycomb portions preferably has a porosity of 5 to 80%, an average pore diameter of preferably 0.5 to 100 μm, and a water absorption of 1 to 95%. It is preferable.
[0015]
Further, in the present invention, the honeycomb structure is further constituted by a plurality of honeycomb portions different in at least one of cell density, partition wall thickness, or radial cross-sectional shape in the through hole in the cell structure. In this case, it is preferable that a plurality of honeycomb portions having different cell structures are provided substantially corresponding to a plurality of honeycomb portions made of materials having different characteristics.
[0016]
In the present invention, the plurality of honeycomb portions having different cell structures are 0.155 to 3.101 cells / mm. ² It preferably has a cell density of (100 to 2000 cells / square inch), and preferably has a partition wall thickness of 25 to 500 μm.
[0017]
In the present invention, the material constituting the plurality of honeycomb portions is at least one selected from the group consisting of cordierite, silicon carbide, silicon nitride, alumina, mullite, lithium aluminum silicate, aluminum titanate, and zirconia. Can be used.
[0018]
Further, in the present invention, if the performance as a catalyst body is to be imparted, at least a part of the partition walls of the honeycomb portion may be loaded with a metal having catalytic ability, and the performance as an adsorbent may be imparted. For example, an adsorption layer having a hydrocarbon adsorption capacity may be provided on at least some of the partition walls of the honeycomb portion, and the performance as a filter for collecting and removing particulate matter contained in the dust-containing fluid is provided. If there is, at least a part of the honeycomb portion is constituted by partition walls having a filtering ability, and through holes formed by the partition walls having the filtering ability are arranged at one end with respect to a predetermined through hole at both end surfaces through which the through holes penetrate. What is necessary is just to seal an end part and to seal the other end part about the remaining through-holes.
[0019]
On the other hand, according to the present invention, there is provided a method for manufacturing a honeycomb structure in which a raw material mainly composed of a ceramic material and a medium are kneaded to obtain a clay, and the clay is extruded and formed. A plurality of raw materials having different properties after firing are used as raw materials, and the plurality of raw materials are kneaded with a medium by different kneading mechanisms to obtain a plurality of clays having different properties after firing. After introducing the clay in different positions on the base and simultaneously extruding And forming a second honeycomb portion that functions as a catalyst body by supporting a metal having catalytic ability on the outer peripheral side, and forms a first honeycomb portion that functions as an exhaust gas filter disposed on the inner peripheral side. A method for manufacturing a honeycomb structure is provided.
[0020]
In the production method of the present invention, as a means for simultaneously extruding a plurality of clays at different positions of the base and simultaneously extruding them, a composite clay integrated with a plurality of clays is introduced into the base, A method in which the clay is extruded simultaneously is preferable.
[0021]
At this time, the composite clay is preferably one in which at least one other clay having different characteristics after firing from the one clay is disposed around one clay made of one material. .
[0022]
Further, in the production method of the present invention, as another means for simultaneously extruding a plurality of clays at different positions of the bases and then simultaneously extruding them, different positions of the bases by different extrusion mechanisms are used. A method of extruding at the same time after being introduced into is also preferable.
[0023]
At this time, a syringe-type extrusion mechanism may be used as the extrusion mechanism, but by using a screw-type extrusion mechanism, the clay obtained by kneading and kneading a raw material mainly composed of a ceramic material and a medium. Extrusion is preferably carried out continuously by a series of steps.
[0024]
Moreover, in the manufacturing method of this invention, it is preferable that the raw material which has a ceramic material as a main component differs in the characteristics after baking chosen from at least 1 sort (s) of a porosity, an average pore diameter, or a water absorption.
[0025]
Further, as the die, at least one of the cell block pitch, the slit width, or the cross-sectional shape in the direction perpendicular to the cell block extrusion direction is substantially different for each part where the clay with different characteristics is introduced. It is also preferable to use it.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings.
[0027]
As shown in FIG. 1, a honeycomb structure 1 of the present invention has a plurality of through holes 3 formed in the axial direction by a plurality of partition walls 2, and the honeycomb structure 1 is made of a material having different characteristics. And a plurality of honeycomb parts 10 and 11 are directly joined and integrated with each other.
[0028]
Thereby, each honeycomb part 10 and 11 can demonstrate different high performance according to the performance calculated | required, Moreover, the local stress by shape mismatch of each honeycomb part 10 and 11 and presence of a joining material There is no concentration, and reliability during use can be improved. This will be specifically described below.
[0029]
In the present invention, the material constituting the plurality of honeycomb portions 10 and 11 includes, for example, cordierite, metal silicon, silicon carbide, silicon nitride, alumina, mullite, lithium aluminum silicate, aluminum titanate, and zirconia. There may be mentioned at least one selected.
[0030]
Examples of the characteristics of the material constituting the honeycomb portions 10 and 11 include porosity, average pore diameter, water absorption, specific heat, and the like. In the present invention, at least one of these characteristics is used. Depending on the performance required for each of the honeycomb portions 10 and 11, it is preferable that they differ.
[0031]
For example, in the honeycomb part 10 used as a catalyst body or an adsorbent, the porosity is preferably 20 to 40%, the average pore diameter is 1 to 80 μm, the water absorption is 1 to 40%, and the porosity is 25 to 35. %, The average pore diameter is preferably 1 to 60 μm, and the water absorption is preferably 4 to 35%.
[0032]
For example, in the honeycomb part 11 used as a filter, the porosity is preferably 40 to 80%, the average pore diameter is preferably 5 to 45 μm, the porosity is 40 to 70%, and the average pore diameter is 10 to 40 μm. More preferably.
[0033]
Moreover, even if the honeycomb parts 10 and 11 impart any performance, considering the weight reduction and strength of the honeycomb structure 1, the porosity is 5 to 80% and the average pore diameter is 0.5 to 100 μm, respectively. The water absorption is preferably 1 to 95%, more preferably 25 to 70%, the average pore diameter is 1 to 60 μm, and the water absorption is 4 to 92%.
[0034]
In the present invention, the honeycomb parts 10 and 11 may be made of different materials so that the material characteristics of the honeycomb parts 10 and 11 are different, and the honeycomb parts 10 and 11 are made of the same material. However, the material characteristics may be different. Examples of the latter include, for example, those made of the same type of material, with different porosities, pore diameters, etc., for example, adding crystal growth aids, pore formers, etc. to the raw material By doing so, such a honeycomb structure can be obtained.
[0035]
As shown in FIGS. 2 and 3, in the honeycomb structure 1 of the present invention, the cell density, partition wall thickness, or It can also be constituted by a plurality of honeycomb portions 12 and 13 which are different in at least one kind such as a radial cross-sectional shape in the through hole.
[0036]
For example, in a honeycomb portion used as a catalyst body or an adsorbent, the cell density is 0.465 to 3.101 cells / mm, respectively. ² (300 to 2000 cells / square inch), the partition wall thickness is preferably 25 to 300 μm, and the cross-sectional shape in the radial direction in the through-hole is preferably triangular, quadrangular, hexagonal, or circular, and the cell density is preferably 0.930 to 3.101 cells / mm ² (600 to 2000 cells / square inch), and the partition wall thickness is more preferably 25 to 100 μm.
[0037]
For example, in the honeycomb part used as a filter, the cell density is 0.155 to 0.620 cell / mm, respectively. ² (100 to 400 cells / square inch), the partition wall thickness is preferably 100 to 500 μm, and the cross-sectional shape in the radial direction in the through hole is preferably a triangle, quadrangle, or hexagon, and the cell density is 0.236 to 0, respectively. .465 cells / mm ² (150 to 300 cells / square inch), the partition wall thickness is preferably 200 to 300 μm, and the radial cross-sectional shape of the through hole is more preferably a square.
[0038]
Further, in any honeycomb part that imparts any performance, the cell density is 0.155 to 3.101 cells / mm, considering the weight reduction and strength of the honeycomb structure 1. ² (100 to 2000 cells / square inch), partition wall thickness is preferably 25 to 500 μm, and cell density is 0.236 to 3.101 cells / mm, respectively. ² (150 to 2000 cells / square inch), and the partition wall thickness is more preferably 25 to 300 μm. Examples of the cross-sectional shape in the radial direction of the through hole include a triangle, a quadrangle, a hexagon, an ellipse, and a circle.
[0039]
As shown in FIG. 2, in the present invention, the plurality of honeycomb portions 12 and 13 having different cell structures are not necessarily provided corresponding to the plurality of honeycomb portions 10 and 11 made of materials having different characteristics. A plurality of honeycomb portions 10 and 11 having different cell structures and a plurality of honeycomb portions 12 and 13 made of materials having different characteristics may be provided at different portions.
[0040]
However, in order to exhibit the high performance required for each honeycomb portion, as shown in FIG. 3, different cells are made substantially corresponding to the plurality of honeycomb portions 10 and 11 made of the materials having different characteristics described above. It is preferable to provide a plurality of honeycomb portions 12 and 13 having a structure.
[0041]
Specifically, the difference between the boundary between the honeycomb portions 10 and 11 made of materials having different characteristics and the boundary between the honeycomb portions 12 and 13 having different cell structures is preferably within 10 cells, It is more preferably within a cell, still more preferably within 5 cells, and particularly preferably within 3 cells.
[0042]
In the honeycomb structure 1 of the present invention, where the plurality of honeycomb portions 10 and 11 made of materials having different characteristics are provided is not particularly limited, and is appropriately determined depending on the required design, performance, and the like. What is necessary is just to provide in the position.
[0043]
For example, as shown in FIG. 1, a plurality of honeycomb parts 10 and 11 made of materials having different characteristics are provided in a central region including the central axis of the honeycomb structure, and the first honeycomb made of material having different characteristics Examples include a portion 11 and a second honeycomb portion 10 made of another material having different characteristics and provided in an adjacent outer peripheral region surrounding the central region.
[0044]
Further, as shown in FIG. 4, as another embodiment, a plurality of honeycomb parts 10 and 11 made of materials having different characteristics are arranged at a substantially equal interval parallel to the central axis of the honeycomb structure 1. The first honeycomb portion 11 made of a material having different characteristics provided in a region having a cylindrical shape, and the other honeycombs having different characteristics provided in an adjacent outer peripheral region surrounding the plurality of regions having a cylindrical shape. The thing comprised by the 2nd honeycomb part 10 which consists of material can be mentioned.
[0045]
As another embodiment, as shown in FIG. 5, when the honeycomb structure 1 is divided into two in the axial direction, the first honeycomb portion 11 made of one material having different characteristics provided in one region; And the second honeycomb portion 10 made of another material having different characteristics provided in the other region; as shown in FIG. 6, the pair of honeycomb structures 1 when divided into four in the axial direction A structure composed of a first honeycomb part 11 made of one material having different characteristics and a second honeycomb part 10 made of another material having different characteristics, which are respectively provided in a pair of regions located at the corners. Can be mentioned.
[0046]
As shown in FIGS. 1 and 4 to 6, the honeycomb structure 1 of the present invention is such that the above-described plurality of honeycomb portions 10 and 11 are directly joined and integrated.
[0047]
Thereby, for example, if each of the honeycomb portions 10 and 11 is made of the same main crystal, the stress concentrated on the joint portion can be reduced and the impact resistance, thermal shock resistance, etc. can be improved. In addition, it is not necessary to join separately manufactured ones with the same dimensions, and the manufacturing process can be simplified. Furthermore, the effective cross-sectional area of the honeycomb structure can be increased by the amount that does not require a joint.
[0048]
Note that a method of directly joining and integrating the plurality of honeycomb portions 10 and 11 will be described in the manufacturing method of the present invention described later.
[0049]
In the honeycomb structure 1 according to the present invention, it is preferable to provide various adducts to the above-described honeycomb portions 10 and 11 in accordance with required performance.
[0050]
For example, in the case of imparting performance as a catalyst carrier, it is preferable to support a metal having catalytic ability on the partition walls 3 of the honeycomb portions 10 and 11 imparting the performance. In this case, the metal having catalytic ability is supported. Examples thereof include Pt, Pd, and Rh.
[0051]
Similarly, when performance as an adsorbent such as hydrocarbon is imparted, it is preferable to provide an adsorption layer that adsorbs hydrocarbon or the like on the partition walls 3 of the honeycomb portions 10 and 11 imparting the performance. In this case, examples of the adsorption layer include a layer made of zeolite, activated carbon or the like, and among them, a layer made of zeolite is preferable from the viewpoint of heat resistance. Moreover, as a zeolite, any of natural products and synthetic products can be used, but those having a Si / Al molar ratio of 40 or more are preferable. For example, ZSM-5, USY, β-zeolite, mordenite, silica A light, a metallosilicate, etc. can be mentioned suitably. These zeolites are preferably used in combination of two or more in order to adsorb hydrocarbons having various molecular sizes.
[0052]
Further, when the performance as a filter is imparted, the partition walls 3 of the honeycomb portions 10 and 11 that impart the performance have the filtering ability made of the material having the above-described characteristics. It is preferable that the through-hole 3 to be formed is sealed at one end face with respect to a predetermined through-hole at both end faces through which the through-hole 3 passes, and the other end face with respect to the remaining through-hole. Thereby, it can be used as a filter for collecting and removing particulate matter contained in the dust-containing fluid.
[0053]
Needless to say, each of the honeycomb portions 10 and 11 in the present invention is not limited to these performances, and various performances may be given depending on the application.
[0054]
In the honeycomb structure 1 of the present invention, the shape of the structure itself is not particularly limited, and may be a polygon such as a triangle, a rectangle, a square, a rhombus, a trapezoid, an ellipse, a circle, Race track A shape such as a shape, a semi-elliptical shape, or a semi-circular shape can be applied.
[0055]
Next, the manufacturing method of the honeycomb structure of the present invention will be described.
In the method for manufacturing a honeycomb structure of the present invention, a raw material mainly composed of a ceramic material is made of a plurality of materials having different properties after firing, and the plurality of materials are separated from the medium by different kneading mechanisms. A plurality of kneaded materials are obtained by kneading, and the plurality of kneaded materials are respectively introduced into different positions of the base, and then the plurality of kneaded materials are extruded simultaneously.
[0056]
According to such a manufacturing method of the present invention, the honeycomb structure of the present invention in which the honeycomb portions having different characteristics after firing are directly joined and integrated can be manufactured at a low cost by a simple and reliable process. it can. This will be specifically described below.
[0057]
First, in the manufacturing method of the present invention, a plurality of raw materials having different characteristics after firing are used as a raw material mainly composed of a ceramic material.
[0058]
Examples of raw materials mainly composed of ceramic materials include metal silicon, silicon carbide, titanium, zirconium, boron carbide, titanium carbide, zirconium carbide, silicon nitride, boron nitride, aluminum nitride, aluminum oxide, zirconium oxide, mullite, cordier. A material containing at least one material selected from the group consisting of an elite raw material, aluminum titanate, sialon, kaolin, talc, aluminum hydroxide, fused silica, and quartz as a main component can be mentioned, What is necessary is just to select suitably according to the performance calculated | required. Moreover, it is good also as a raw material corresponding to the performance calculated | required after sintering by further including other materials, such as a crystal growth adjuvant and a pore making material, as an additive. Needless to say, a dispersant, a binder, or the like may be added as an additive.
[0059]
Examples of the characteristics after firing of the raw material mainly composed of a ceramic material include porosity, average pore diameter, water absorption, specific heat, and the like. In the present invention, at least one of these characteristics is different. It is preferable to use raw materials.
The desired range of these characteristics is the same as that shown in the honeycomb structure of the present invention, and it is preferable to prepare the raw material so that such characteristics can be obtained after sintering.
[0060]
In addition, as a raw material of the part used as a catalyst body, an adsorbent body, or a filter, what has cordierite, SiC, etc. as a main component can be mentioned.
[0061]
In the production method of the present invention, next, materials having different properties after firing are kneaded with a medium or the like by different kneading mechanisms to obtain a plurality of clays.
[0062]
In the present invention, the kneading mechanism is not particularly limited. For example, the kneading mechanism may be kneaded using a vacuum kneader, but the kneading step and the extrusion step are performed in a series of steps using a screw-type extrusion mechanism described later. It is preferable to carry out continuously from the point of productivity improvement.
[0063]
In the present invention, the medium is not particularly limited, and a preferable medium may be used according to the above-described raw materials.
[0064]
In the production method of the present invention, next, a plurality of clays having different characteristics after firing are introduced into different positions of the die, and then the plurality of clays are simultaneously extruded and formed.
[0065]
As a means for simultaneously extruding the obtained multiple clays having different characteristics after firing at different positions on the die, and simultaneously extruding the multiple clays having different characteristics after firing, The method of producing and extruding this composite clay can be mentioned. At this time, for example, as shown in FIG. 7, the composite clay is at least one or more other than the one clay 20 around the one clay 20 made of one material and having different characteristics after firing. Can be obtained by arranging and integrating the clay 21. In such a composite clay 22, a honeycomb structure in which honeycomb portions made of materials having different characteristics can be directly joined with a single syringe-type extrusion mechanism can be obtained.
[0066]
In the case where the first honeycomb portion provided in the central region and the second honeycomb portion provided in the outer peripheral region are provided at a position where the central axis of the honeycomb structure is substantially concentric, one material is used. The other clay 21 made of a material having different characteristics after firing may be provided at a position that is substantially concentric.
[0067]
Further, in the present invention, in order to produce a honeycomb structure by extrusion molding, the composite clay 22 described above includes the clays 20 and 21 made of materials having different characteristics after firing in a direction perpendicular to the extrusion direction. It is preferable that they are laminated.
Moreover, in order to improve the moldability at the time of extrusion molding, it is preferable that the gaps between the plurality of clays 20 and 21 having different characteristics after firing are reduced and closely bonded.
[0068]
As another means of simultaneously extruding a plurality of clays made of materials having different characteristics after being introduced into different positions of the die, and simultaneously extruding a plurality of clays having different characteristics after firing, different extrusion mechanisms Thus, it is possible to mention a method of introducing into different positions of the die and simultaneously extruding.
[0069]
Specifically, as shown in FIGS. 8 (a) and 8 (b), a plurality of syringe-type extrusion mechanisms 18 and 19 are used as the extrusion mechanism, and a plurality of clays 20 and 21 having different characteristics after firing are obtained. A method of simultaneously extruding the clays 20 and 21 by putting them into the syringe-type extrusion mechanisms 18 and 19 and performing the extrusion process in each of the extrusion mechanisms 18 and 19 in synchronism, or FIG. As shown in b), a plurality of screw-type extrusion mechanisms 16 and 17 are used as the extrusion mechanism, the kneading step of the raw material and the medium in each of the extrusion mechanisms 16 and 17, and the extrusion of the clay obtained by the kneading. A method of extruding each of the clays 20 and 21 at the same time can be mentioned by performing the processes in synchronization.
[0070]
Among these, the latter using the screw-type extrusion mechanisms 16 and 17 in that kneading of the raw material and the medium and extrusion of the clay obtained by the kneading can be continuously performed and productivity can be extremely increased. This method is preferred.
[0071]
Moreover, as an arrangement | positioning of an extrusion mechanism, as shown to FIG. 10 (a) (b), for example, corresponding to each site | part 26,27 which introduce | transduces each clay from which the characteristic after baking in the nozzle | cap | die 25 differs, The thing which has arrange | positioned each extrusion mechanism 16 and 17 can be mentioned. However, as shown in FIGS. 9A and 9B, the extrusion mechanism 17 and a specific part of the base 25 are communicated with at least one of the extrusion mechanisms 17, and the clay is introduced into the specific part of the base 25. It is also preferable to provide a guide portion 28 and freely dispose the extrusion mechanisms 16 and 17 according to the design or the like. In addition, in the extrusion mechanism 17 provided with the guide portion 28, the design of the extrusion mechanism itself can be made extremely simple.
[0072]
In the present invention, there is no particular limitation on the shape and structure of the die used, for example, when providing a plurality of honeycomb portions having different cell structures such as cell density, partition wall thickness, or cross-sectional shape in the radial direction of the through hole. Depending on the required cell structure, it is preferable that at least one of the cell block pitch, the slit width, or the cross-sectional shape perpendicular to the cell block extrusion direction is made different.
[0073]
In addition, when a plurality of honeycomb portions having different cell structures are provided substantially corresponding to a plurality of honeycomb portions made of materials having different characteristics, the cell structure is changed for each portion into which clay having substantially different characteristics is introduced. It is preferable to make them different.
[0074]
Specifically, the difference between the boundary of each part of the die where the clay having different characteristics after firing is introduced and the boundary of each part of the die having a different shape and structure is preferably within 10 cells. More preferably, it is within 7 cells, more preferably within 5 cells, and particularly preferably within 3 cells.
[0075]
In the production method of the present invention, the obtained honeycomb structure is usually fired to obtain a final product. In general, firing is preferably performed after the molded body is dried by microwaves and / or hot air.
[0076]
【Example】
EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.
The honeycomb structures obtained in the examples and comparative examples were evaluated by the following methods.
[0077]
(Evaluation methods)
1. Average pore diameter
Measurements were made with a mercury intrusion porosimeter manufactured by Micromeritic.
2. Porosity
It calculated | required by calculation from the true specific gravity of the constituent material of a honeycomb structure, and the total pore volume. The pore volume was measured with a mercury intrusion porosimeter manufactured by Micromeritic.
3. Water absorption
It was measured by the method described in JIS R2205.
[0078]
(Examples and Comparative Examples)
Example 1
First, as the ceramic raw material, a first ceramic raw material and a second ceramic raw material each made of a cordierite-forming material having different characteristics after firing were prepared.
[0079]
Next, each ceramic raw material is put into different vacuum kneaders together with water used as a medium, each ceramic raw material and water are kneaded and molded, and the first ceramic raw material having a cylindrical shape with a diameter of 150 mm is used. And a clay made of a second ceramic material having a flat plate shape with a width of 475 mm and a thickness of 40 mm was obtained.
[0080]
Next, a composite clay was produced by winding a clay made of the second ceramic material having a flat plate shape around the clay made of the first ceramic material having a cylindrical shape.
[0081]
Next, the obtained columnar composite clay was put into a ram type extrusion molding machine in which a base having a different cell structure was arranged at a central portion having a diameter of 120 mm and an outer peripheral portion thereof, and extrusion molding was performed.
[0082]
Next, after drying the obtained molded body with hot air and microwave, the through holes of the honeycomb portion made of the first ceramic raw material are alternately plugged at the both end faces that pass through and fired, and then the second ceramic raw material The honeycomb part is made of a cylindrical part having a length of 190 mm and a diameter of 190 mm. The honeycomb part made of the first ceramic material has a diameter of 120 mm concentric with the honeycomb structure. A honeycomb structure provided in a cylindrical region was obtained.
[0083]
When the characteristics of the obtained honeycomb structure were investigated, the honeycomb part made of the first ceramic raw material had an average pore diameter of 30 μm, a water absorption rate of 91%, a porosity of 70%, a partition wall thickness of 0.25 mm, a cell density of 0.1%. 465 cells / mm ² (300 cells / square inch), the cross-sectional shape in the radial direction of the through-hole is a quadrangle, and the honeycomb part made of the second ceramic raw material has an average pore diameter of 5 μm, a water absorption rate of 17%, a porosity of 30%, and a partition wall thickness. 0.1 mm, cell density 0.930 cell / mm ² (600 cells / square inch), and the through hole had a quadrangular cross-sectional shape in the radial direction.
[0084]
Further, as shown in FIG. 11, the honeycomb structure 1 is held by a metal case 40, and an exhaust pipe 41 of a 2400cc diesel engine is disposed corresponding to the first honeycomb portion 11 made of the first ceramic material. Thus, an exhaust gas purification device was produced.
[0085]
Exhaust gas is introduced from an exhaust gas introduction passage 39 formed by the outer wall of the exhaust pipe 41 and the inner wall of the metal case, and NO is made of NO. ₂ The exhaust gas is sequentially passed through a second honeycomb portion 10 that functions as a catalyst body for conversion into a first honeycomb portion 11 and a first honeycomb portion 11 that is made of a first ceramic material and functions as a filter for collecting and removing particulate matter. When purified, excellent exhaust gas purification performance was observed. Further, when the honeycomb structure after the test was confirmed for damage, deformation, etc., no damage such as peeling, cracking, deformation of the through-holes, etc. were observed including the joint portion of both honeycomb portions. In addition, the arrow in FIG. 11 shows the advancing direction of exhaust gas.
[0086]
Example 2
First, as the ceramic raw material, a first ceramic raw material and a second ceramic raw material made of silicon carbide materials each having different characteristics after firing were prepared.
[0087]
Next, one screw type extrusion mechanism for extruding the first ceramic raw material is provided corresponding to the central portion of the diameter 90 mm concentric with the central point of the inlet end face of the die, and the other ceramic raw material is extruded. The screw-type extrusion mechanism uses an extrusion molding apparatus having a guide part communicating with the outer peripheral part concentric with the central part of the above-mentioned die. Each ceramic raw material together with the medium is put into a different screw-type extrusion mechanism and kneaded. And, extrusion molding of each kneaded material obtained was performed in synchronization with each extrusion mechanism, and a formed body having a honeycomb structure was manufactured. At this time, as the caps, those having different cell structures at the central part and the outer peripheral part were used.
[0088]
Next, the obtained molded body was dried by microwaves, and the through holes of the honeycomb portion made of the first ceramic raw material were alternately plugged at the both end surfaces penetrating, and then fired. Thereafter, a catalyst having Pt as a main component is supported on the partition walls of the honeycomb portion made of the second ceramic material, and the honeycomb portion made of the first ceramic material is a cylindrical region having a diameter of 90 mm concentric with the honeycomb structure. A provided columnar honeycomb structure having a length of 152 mm and a diameter of 144 mm was obtained.
[0089]
When the characteristics of the obtained honeycomb structure were investigated, the honeycomb part made of the first ceramic raw material had an average pore diameter of 10 μm, a porosity of 45%, a water absorption rate of 27%, a partition wall thickness of 0.3 mm, a cell density of 0. 310 cells / mm ² (200 cells / square inch), the cross-sectional shape of the through hole in the radial direction is quadrilateral, and the honeycomb part made of the second ceramic raw material has an average pore diameter of 4 μm, a porosity of 20%, a water absorption of 9%, and a partition wall thickness of 0 .15mm, cell density 0.620 cells / mm ² (400 cells / square inch), the cross-sectional shape of the through hole in the radial direction was a hexagon.
[0090]
Further, as shown in FIG. 11, the honeycomb structure 1 is gripped by a metal case 40, and an exhaust pipe 41 of a 2400cc diesel engine is arranged so as to correspond to the first honeycomb portion 11 made of the first ceramic material. And an exhaust gas purification device was produced.
[0091]
Exhaust gas is introduced from an exhaust gas introduction passage 39 formed by the outer wall of the exhaust pipe 41 and the inner wall of the metal case, and NO is made of NO. ₂ The exhaust gas is sequentially passed through a second honeycomb portion 10 that functions as a catalyst body for conversion into a first honeycomb portion 11 and a first honeycomb portion 11 that is made of a first ceramic material and functions as a filter for collecting and removing particulate matter. When purified, excellent exhaust gas purification performance was observed. Further, when the honeycomb structure after the test was confirmed for damage, deformation, etc., no damage such as peeling, cracking, deformation of the through-holes, etc. were observed including the joint portion of both honeycomb portions. In addition, the arrow in FIG. 11 shows the advancing direction of exhaust gas.
[0092]
Example 3
First, as the ceramic raw material, a first ceramic raw material and a second ceramic raw material each made of a cordierite-forming material having different characteristics after firing were prepared.
[0093]
Next, one screw type extrusion mechanism for extruding the first ceramic raw material is disposed corresponding to the central portion of the die, and another screw type extrusion mechanism having a plurality of screws for extruding the second ceramic raw material is provided. Using an extrusion molding device arranged on the outer periphery of one screw-type extrusion mechanism, each ceramic material is put into a different screw-type extrusion mechanism to knead each ceramic material, and to extrude each obtained clay Were performed in synchronism with each extrusion mechanism to produce a honeycomb structure formed body. At this time, as the caps, those having different cell structures at the central part and the outer peripheral part were used.
[0094]
Next, after drying and firing the obtained formed body, the honeycomb part made of the first ceramic raw material is supported on the partition walls of the honeycomb part made of the second ceramic raw material by supporting a catalyst mainly composed of Pt and Pd. Is provided with an adsorption layer mainly composed of zeolite ZSM-5 (manufactured by The PQ Co., Ltd.), and the honeycomb portion made of the first ceramic material is a cylindrical shape having a diameter of 45 mm concentric with the honeycomb structure. A columnar honeycomb structure having a length of 152 mm and a diameter of 144 mm provided in the region was obtained.
[0095]
When the characteristics of the obtained honeycomb structure were investigated, the honeycomb part made of the first ceramic material had an average pore diameter of 3 μm, a water absorption of 10%, a porosity of 20%, a partition wall thickness of 150 μm, and 0.620 cells / mm. ² (Cell density 400 cells / square inch), radial cross-sectional shape of through-hole, and honeycomb part made of the second ceramic material has an average pore diameter of 7 μm, water absorption of 22%, porosity of 35%, partition wall thickness 100 μm, cell density 0.465 cells / mm ² (300 cells / square inch), the cross-sectional shape in the radial direction of the through hole was a hexagon.
[0096]
The honeycomb structure was held by a metal case, and an exhaust pipe of a 3000 cc gasoline engine was disposed corresponding to one end face of the honeycomb structure to produce an exhaust gas purification device.
[0097]
The second honeycomb part that functions as a three-way catalyst body made of the second ceramic raw material that oxidizes and reduces HC, CO, and NOx, and the adsorbent that consists of the first ceramic raw material and adsorbs hydrocarbon components When introduced into the first honeycomb portion to purify the exhaust gas, excellent exhaust gas purification performance was observed. Further, when the honeycomb structure after the test was confirmed for damage, deformation, etc., no damage such as peeling, cracking, deformation of the through-holes, etc. were observed including the joint portion of both honeycomb portions.
[0098]
Comparative Example 1
Example 1 except that a raw material made of one kind of cordierite-forming material having the same characteristics after firing was used as the ceramic raw material, and a base having the same cell structure as a whole was used. In the same manner, a cylindrical honeycomb structure having a length of 203 mm and a diameter of 190 mm was obtained.
[0099]
When the characteristics of the obtained honeycomb structure were investigated, the average honeycomb diameter was 7 μm, the water absorption rate was 22%, the porosity was 35%, the partition wall thickness was 0.25 mm, and the cell density was 0.465 cells / mm. ² (300 cells / square inch), the cross-sectional shape in the radial direction of the through hole was a quadrangle.
[0100]
Further, as shown in FIG. 11, the honeycomb structure 1 is held by a metal case 40, and an exhaust pipe 41 of a 2400cc diesel engine is mounted so as to correspond to the first honeycomb portion 11 made of the first ceramic material. An exhaust gas purification device was produced.
[0101]
Exhaust gas is introduced from an exhaust gas introduction path 39 formed by the outer wall of the exhaust pipe 41 and the inner wall of the metal case, and NO is NO. ₂ When exhaust gas is purified through the second honeycomb part 10 functioning as a catalyst body for conversion into the first and the first honeycomb part 11 functioning as a filter for collecting and removing particulate matter, a filter is obtained. As a result, the pressure loss of the first honeycomb portion 11 that was caused to function as was increased more than three times compared with the honeycomb structure of Example 1, and did not sufficiently function as an exhaust gas purification device.
In addition, the arrow in FIG. 11 shows the advancing direction of exhaust gas.
[0102]
【The invention's effect】
As explained above, according to the present invention, it is possible to exhibit different high performances according to requirements for each honeycomb part, and local stress due to shape mismatch of each honeycomb part and the presence of a bonding material. There can be provided a honeycomb structure that is not concentrated and has high reliability during use, and is particularly suitable for an exhaust gas purification system, a heat exchanger, a solid electrolyte battery, a thermoacoustic engine such as an acoustic wave cooling device, and the like.
In addition, the present invention can provide a manufacturing method that can manufacture a honeycomb structure having such excellent characteristics at a low cost by a simple and reliable process.
[Brief description of the drawings]
FIG. 1 is a perspective view schematically showing one embodiment of a honeycomb structure of the present invention.
FIG. 2 is a plan view schematically showing an example of an arrangement relationship between a plurality of honeycomb parts made of materials having different characteristics and a honeycomb part having a different cell structure in the honeycomb structure of the present invention.
Fig. 3 is a plan view schematically showing another example of a positional relationship between a plurality of honeycomb portions made of materials having different characteristics and honeycomb portions having different cell structures in the honeycomb structure of the present invention.
Fig. 4 is a perspective view schematically showing another embodiment of the honeycomb structure of the present invention.
Fig. 5 is a perspective view schematically showing still another embodiment of the honeycomb structure of the present invention.
Fig. 6 is a perspective view schematically showing still another embodiment of the honeycomb structure of the present invention.
FIG. 7 is a process chart schematically showing an example of a method for producing a composite clay in the method for manufacturing a honeycomb structure of the present invention.
8A is a partial cross-sectional view schematically showing an example of an extrusion mechanism used in the method for manufacturing a honeycomb structure of the present invention, and FIG. 8B is an arrangement of guide portions in FIG. 8A. It is a partial cross section figure in the position of A which shows.
9 (a) is a partial cross-sectional view schematically showing another example of an extrusion mechanism used in the method for manufacturing a honeycomb structure of the present invention, and FIG. 9 (b) is a guide portion of FIG. 9 (a). It is a partial cross section figure in the position of B which shows arrangement | positioning.
Fig. 10 (a) is a partial cross-sectional view schematically showing still another example of an extrusion mechanism used in the method for manufacturing a honeycomb structure of the present invention, and Fig. 10 (b) is a guide of Fig. 10 (a). It is a partial cross section figure in the position of C which shows arrangement | positioning of a part.
FIG. 11 is a half cross-sectional view showing an exhaust gas purification apparatus in which a honeycomb structure according to an example of the present invention or a comparative example is mounted on an exhaust pipe of a diesel engine.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Honeycomb structure, 2 ... Partition, 3 ... Through-hole 10, 11 ... Honeycomb part (10 ... 2nd honeycomb part, 11 ... 1st honeycomb part) which consists of material of a different characteristic, 12, 13 ... Cell Honeycomb parts having different structures, 16, 17 ... Extrusion mechanism (screw type extrusion mechanism), 16a, 17a ... Screw, 18, 19 ... Extrusion mechanism (syringe type extrusion mechanism), 18a, 19a ... Piston, 20 ... One clay 21 ... Other clays, 25 ... Bases, 26, 27 ... Sites for introducing the clays of the bases, 28 ... Guide portions, 31 ... Honeycomb structure (before firing), 39 ... Exhaust gas introduction path, 40 ... Metal Case, 41 ... exhaust pipe.

Claims

A honeycomb structure in which a plurality of through holes are formed in the axial direction by a plurality of partition walls,
The honeycomb structure includes a second honeycomb portion that functions as a catalyst body and a first honeycomb portion that functions as an exhaust gas filter disposed on the inner peripheral side of the honeycomb structure, and the first honeycomb portion and the second honeycomb portion A honeycomb structure characterized in that the honeycomb portions are made of materials having different characteristics , and the first and second honeycomb portions are directly joined and integrated.

The outer peripheral region the first and the second plurality of honeycomb unit is provided in a central region including a central axis of the honeycomb structure, a first honeycomb section functioning as exhaust gas filter, the adjacent surrounding the central region The honeycomb structure according to claim 1, comprising a second honeycomb portion that functions as a catalyst body provided in the structure.

The honeycomb structure according to claim 1 or 2, wherein materials constituting the plurality of honeycomb portions differ in at least one characteristic of porosity, average pore diameter, or water absorption.

The honeycomb structure according to any one of claims 1 to 3, wherein a material constituting the plurality of honeycomb portions has a porosity of 5 to 80%.

The honeycomb structure according to any one of claims 1 to 4, wherein a material constituting the plurality of honeycomb portions has an average pore diameter of 0.5 to 100 µm.

The honeycomb structure according to any one of claims 1 to 5, wherein a material constituting the plurality of honeycomb portions has a water absorption rate of 1 to 95%.

The honeycomb structure according to any one of claims 1 to 6, wherein the honeycomb structure includes a plurality of honeycomb portions different in at least one of a cell density, a partition wall thickness, and a radial cross-sectional shape in the through hole in the cell structure. The honeycomb structure according to any one of claims.

The honeycomb structure according to any one of claims 1 to 7, wherein the plurality of honeycomb portions having different cell structures are provided substantially corresponding to the plurality of honeycomb portions made of the material having different characteristics. .

The honeycomb unit of said plurality of honeycomb structure according to any one of claims 1-8 having a cell density of 0.155 to 3.101 cells ^/ mm 2 (100 to 2000 cells / square inch).

The honeycomb structure according to any one of claims 1 to 9, wherein the partition walls of the plurality of honeycomb portions have a thickness of 25 to 500 µm.

The material constituting the plurality of honeycomb portions is at least one selected from the group consisting of cordierite, silicon carbide, silicon nitride, alumina, mullite, lithium aluminum silicate, aluminum titanate, and zirconia. The honeycomb structure according to any one of 10.

The honeycomb structure according to any one of claims 1 to 11, wherein a part of the plurality of honeycomb parts is formed by supporting a metal having catalytic ability on the partition walls.

The honeycomb structure according to any one of claims 1 to 12, wherein a part of the plurality of honeycomb portions has an adsorption layer that adsorbs hydrocarbons to the partition walls.

Part of the plurality of honeycomb portions is constituted by partition walls having a filtering ability, and through holes formed by the partition walls having the filtering ability are arranged at both end surfaces through which the through holes pass, The honeycomb structure according to any one of claims 1 to 13, wherein the end of each of the first and second through-holes is sealed, and the remaining through-hole is sealed by sealing the other end.

The honeycomb structure according to claim 14, which is used as a filter for collecting and removing particulate matter contained in a dust-containing fluid.

A method for manufacturing a honeycomb structure in which a raw material mainly composed of a ceramic material and a medium are kneaded to obtain a clay, and the clay is extruded and formed.
As a raw material mainly composed of the ceramic material, a plurality of raw materials having different characteristics after firing are used,
The plurality of raw materials are kneaded with the medium by different kneading mechanisms to obtain a plurality of clays having different characteristics after firing,
After the plurality of clays are introduced into different positions of the bases, respectively, the plurality of clays are simultaneously extruded , and a second honeycomb portion that functions as a catalyst body is loaded with a metal having catalytic ability on the outer peripheral side thereof. A method for manufacturing a honeycomb structure, comprising forming a first honeycomb portion that functions as an exhaust gas filter that is formed and disposed on an inner peripheral side thereof .

The method for manufacturing a honeycomb structure according to claim 16, wherein a composite clay in which the plurality of clays are integrated is introduced into the base, and the plurality of clays are extruded simultaneously.

The composite clay is formed by arranging at least one or more other clays having different characteristics after firing from the one clay around one clay made of one material. Item 18. A method for manufacturing a honeycomb structured body according to Item 17.

The method for manufacturing a honeycomb structured body according to claim 16, wherein the plurality of clays are introduced into different positions of the die by different extrusion mechanisms and simultaneously extruded.

The extrusion mechanism is a screw-type extrusion mechanism that continuously kneads the raw material mainly composed of the ceramic material and the medium and extrudes the clay obtained by the kneading through a series of steps. 20. A method for manufacturing a honeycomb structure according to item 19.

21. The method for manufacturing a honeycomb structured body according to any one of claims 16 to 20, wherein the plurality of raw materials differ in at least one of porosity, average pore diameter, and water absorption among the characteristics after firing.

At least one of the cell block pitch, the slit width, or the cross-sectional shape perpendicular to the extrusion direction of the cell block of the die is substantially at each site where each clay having different characteristics after firing is introduced. The manufacturing method of the honeycomb structure according to any one of claims 16 to 21, which is different.