JP2005290991A

JP2005290991A - Catalyst converter retaining member, manufacture method thereof, and catalyst converter

Info

Publication number: JP2005290991A
Application number: JP2004102579A
Authority: JP
Inventors: Junya Sato; 絢也佐藤; Shinya Tomosue; 信也友末; Tadashi Sakane; 忠司坂根
Original assignee: Nichias Corp
Current assignee: Nichias Corp
Priority date: 2004-03-31
Filing date: 2004-03-31
Publication date: 2005-10-20

Abstract

<P>PROBLEM TO BE SOLVED: To provide a catalyst converter holding material, in which no embrittlement of fibers occurs even at high temperature, or specifically, in a temperature range up to 1200°C. <P>SOLUTION: A catalyst converter is composed of catalyst carrier, a casing to contain the catalyst carrier, and holding material installed on the catalyst carrier to be provided between the holding carrier and the casing. The catalyst converter holding material includes at least either highly crystallized mullite fibers with the mullite ratio of 75-90% or highly crystallized alumina fibers with the α-corundum ratio of 30-60%. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

本発明は、例えば自動車等の排気ガス浄化用触媒コンバーターに用いられる触媒担体の保持材及びその製造方法並びに触媒コンバーターに関する。 The present invention relates to a support material for a catalyst carrier used in, for example, an exhaust gas purifying catalytic converter for automobiles, a method for producing the same, and a catalytic converter.

自動車の排気ガス中に含まれる一酸化炭素、炭化水素、窒素酸化物等を除去する目的で、エキゾーストマニホールド直後の部位及び自動車床下の排気ガス流路に筒状のハニカム型触媒担体を配置している。この触媒担体と、これを収容する金属製ケーシングとの間隙を埋め、かつ触媒担体を保持する用途で保持材が用いられているが、シール性能とともに耐熱性や断熱性が必要であることから、無機繊維に無機バインダーや有機バインダーを混合し、一定厚さに集成した繊維質の断熱材が多用されている（例えば、特許文献１、２及び３参照）。 For the purpose of removing carbon monoxide, hydrocarbons, nitrogen oxides, etc. contained in the exhaust gas of automobiles, a cylindrical honeycomb type catalyst carrier is arranged in a part immediately after the exhaust manifold and in an exhaust gas flow path under the automobile floor. Yes. A holding material is used for the purpose of filling the gap between the catalyst carrier and the metal casing that accommodates the catalyst carrier and holding the catalyst carrier, but since heat resistance and heat insulation are required along with sealing performance, BACKGROUND ART A fibrous heat insulating material in which an inorganic binder or an organic binder is mixed with inorganic fibers and assembled to a certain thickness is often used (for example, see Patent Documents 1, 2, and 3).

保持材を構成する無機繊維として、アルミナ繊維、シリカ繊維、ガラス繊維、ロックウール、セラミック繊維等が知られているが、これらの無機繊維は、結晶化率が高いほど柔軟性が低くなり、これを保持材に用いた場合、筒状の触媒担体に装着したり、金属製ケースへの圧入が困難になることから、従来では結晶化率の低いものが選定されている。しかしながら、排気ガス規制は年々厳しくなっており、触媒の反応効率を良くするためにより高い温度域での処理が必要で、保持材もより高温に晒されることから、無機繊維の結晶化が進行したり、結晶粒が成長する等して繊維が脆化し、保持能力が低下することが懸念される。 As the inorganic fiber constituting the holding material, alumina fiber, silica fiber, glass fiber, rock wool, ceramic fiber, etc. are known. However, the higher the crystallization rate, the lower the flexibility of these inorganic fibers. When is used as a holding material, it is difficult to mount it on a cylindrical catalyst carrier or press-fit into a metal case. However, exhaust gas regulations are becoming stricter year by year, and in order to improve the reaction efficiency of the catalyst, it is necessary to process in a higher temperature range, and the holding material is also exposed to a higher temperature. There is a concern that the fibers become brittle due to growth of crystal grains or the like, and the holding ability decreases.

特開平7−２８６５１４号公報JP 7-286514 A 特開２００２−２９２２４３号公報JP 2002-292243 A 特開２００３−２０９３８号公報JP 2003-20938 A

上記のように、触媒担体、保持材を含む環境温度が１０００℃を超える条件となる場合が想定されるが、触媒コンバーターの使用温度の高温化に対して十分に対応できていない状況にある。従って、本発明の目的は、より高温、具体的には１２００℃までの温度範囲においても繊維の脆化の起こらない触媒コンバーター用保持材を提供することにある。 As described above, it is assumed that the environmental temperature including the catalyst carrier and the holding material exceeds 1000 ° C., but the situation is not sufficient for increasing the operating temperature of the catalytic converter. Accordingly, an object of the present invention is to provide a holding material for a catalytic converter which does not cause embrittlement of fibers even at a higher temperature, specifically up to 1200 ° C.

本発明者等は、上記の目的を達成するため検討を重ねた結果、保持材に用いる低結晶化無機繊維に、ムライト化率が７５〜９０％もしくはα−コランダム化率が3０〜６０％である高結晶化無機繊維を混合させることにより、１２００℃という環境下でも繊維の脆化が起こらず、上記目的を達成できることを見いだし本発明を完成するに至った。 As a result of repeated studies to achieve the above object, the present inventors have found that the low crystallization inorganic fiber used for the holding material has a mullite conversion rate of 75 to 90% or an α-corundum conversion rate of 30 to 60%. It has been found that by mixing certain highly crystallized inorganic fibers, the fiber can not be embrittled even in an environment of 1200 ° C., and the above object can be achieved, and the present invention has been completed.

即ち、本発明は、以下のとおりである。
（１）触媒担体と、触媒担体を収容するケーシングと、触媒担体に装着されて触媒担体とケーシングとの間隙に介装される保持材とから構成される触媒コンバーターにおける前記保持材であって、ムライト化率が７５〜９０％である高結晶化ムライト繊維及びα−コランダム化率が３０〜６０％である高結晶化アルミナ繊維の少なくとも一方を含むことを特徴とする触媒コンバーター用保持材。
（２）１２００℃における圧縮復元荷重が０Ｎ／ｃｍ²を越えることを特徴とする上記（１）に記載の触媒コンバーター用保持材。
（３）結晶化率が０を超え１０％未満である低結晶化無機繊維を含むことを特徴とする上記（１）または（２）に記載の触媒コンバーター用保持材。
（４）結晶化率が０％である非晶質無機繊維を含むことを特徴とする上記（１）〜（３）の何れか一項に記載の触媒コンバーター用保持材。
（５）前記低結晶化無機繊維及び前記非晶質無機繊維の少なくとも一方を、繊維全量の１０〜９０質量％含有することを特徴とする上記（３）または（４）に記載の触媒コンバーター用保持材。
（６）前記高結晶化ムライト繊維及び前記高結晶化アルミナ繊維の少なくとも一方と、前記低結晶化無機繊維及び前記非晶質無機繊維の少なくとも一方との混合物が所定厚に集成されていることを特徴とする上記（３）〜（５）の何れか１項に記載の触媒コンバーター用保持材。
（７）組成の異なる少なくとも２層を積層してなることを特徴とする上記（３）〜（６）の何れか１項に記載の触媒コンバーター用保持材。
（８）前記高結晶化ムライト繊維及び前記高結晶化アルミナ繊維の少なくとも一方の含有量が、触媒担体と接する面が最も高く、内部に向かって漸減していることを特徴とする上記（３）〜（７）の何れか１項に記載の触媒コンバーター用保持材。
（９）触媒担体と、触媒担体を収容するケーシングと、触媒担体に装着されて触媒担体とケーシングとの間隙に介装される保持材とから構成される触媒コンバーターにおける前記保持材の製造方法であって、ムライト化率が７５〜９０％である高結晶化ムライト繊維及びα−コランダム化率が３０〜６０％である高結晶化アルミナ繊維の少なくとも一方を含む水性スラリーを、平板状もしくは触媒担体の外形形状と同様形状に吸引脱水成形して成形体を作製し、次いで、前記成形体を乾燥することを特徴とする触媒コンバーター用保持材の製造方法。
（１０）前記水性スラリーが、結晶化率が０を超え１０％未満である低結晶化無機繊維及び結晶化率が０％である非晶質無機繊維の少なくとも一方を含むことを特徴とする上記（９）に記載の触媒コンバーター用保持材の製造方法。
（１１）前記高結晶化ムライト繊維及び前記高結晶化アルミナ繊維の少なくとも一方、並びに前記低結晶化無機繊維及び前記非晶質無機繊維の少なくとも一方の固形分濃度の異なる複数の水性スラリーを調製し、固形分濃度の高い水性スラリーから固形分濃度の低い水性スラリーの順序にて吸引脱水成形を多段に行って成形体を作製し、次いで、前記成形体を乾燥することを特徴とする上記（１０）または（１１）に記載の触媒コンバーター用保持材の製造方法。
（１２）前記高結晶化ムライト繊維及び前記高結晶化アルミナ繊維の少なくとも一方と、前記低結晶化無機繊維及び前記非晶質無機繊維の少なくとも一方との重量比率が異なる複数の水性スラリーを調製し、第１の重量比率の水性スラリーを用いて吸引脱水成形して成形体を作製し、該成形体を第２の重量比率の水性スラリー中に配置して吸引脱水成形する操作を繰り返し行うことを特徴とする上記（１０）または（１１）に記載の触媒コンバーター用保持材の製造方法。
（１３）乾燥後の成形体の触媒担体と接する面を７００℃で焼成することを特徴とする上記（９）〜（１２）の何れか１項に記載の触媒コンバーター用保持材の製造方法。
（１４）触媒担体と、触媒担体を収容するケーシングと、触媒担体に装着されて触媒担体とケーシングとの間隙に介装される保持材とから構成される触媒コンバーターにおける前記保持材の製造方法であって、ムライト化率が７５〜９０％である高結晶化ムライト繊維及びα−コランダム化率が３０〜６０％である高結晶化アルミナ繊維の少なくとも一方、あるいは前記低結晶化無機繊維及び前記非晶質無機繊維の少なくとも一方を添加して乾式混合した混合物を、所定の厚さに集成した後、ニードルパンチング処理を施すことを特徴とする触媒コンバーター用保持材の製造方法。
（１５）触媒担体と、触媒担体を収容するケーシングと、触媒担体に装着されて触媒担体とケーシングとの間隙に介装される保持材とから構成される触媒コンバーターであって、前記保持材として上記（１）〜（８）の何れか１項に記載の保持材が装着されていることを特徴とする触媒コンバーター。 That is, the present invention is as follows.
(1) The holding material in a catalytic converter comprising a catalyst carrier, a casing that accommodates the catalyst carrier, and a holding material that is attached to the catalyst carrier and interposed in a gap between the catalyst carrier and the casing, A holding material for a catalytic converter comprising at least one of highly crystallized mullite fibers having a mullite conversion rate of 75 to 90% and highly crystallized alumina fibers having an α-corundum conversion rate of 30 to 60%.
(2) The holding material for a catalytic converter as described in (1) above, wherein the compression recovery load at 1200 ° C. exceeds 0 N / cm ² .
(3) The holding material for a catalytic converter as described in (1) or (2) above, comprising low-crystallization inorganic fibers having a crystallization rate of more than 0 and less than 10%.
(4) The holding material for a catalytic converter according to any one of (1) to (3) above, comprising amorphous inorganic fibers having a crystallization rate of 0%.
(5) The catalytic converter as described in (3) or (4) above, wherein at least one of the low-crystallized inorganic fiber and the amorphous inorganic fiber is contained in an amount of 10 to 90% by mass based on the total amount of the fiber. Retaining material.
(6) A mixture of at least one of the highly crystallized mullite fiber and the highly crystallized alumina fiber and at least one of the low crystallized inorganic fiber and the amorphous inorganic fiber is assembled to a predetermined thickness. The holding material for a catalytic converter according to any one of the above (3) to (5), which is characterized in that
(7) The holding material for a catalytic converter according to any one of (3) to (6), wherein at least two layers having different compositions are laminated.
(8) The above (3), wherein the content of at least one of the highly crystallized mullite fiber and the highly crystallized alumina fiber is highest on the surface in contact with the catalyst carrier and gradually decreases toward the inside. The holding | maintenance material for catalytic converters in any one of-(7).
(9) A method for producing the holding material in a catalytic converter comprising a catalyst carrier, a casing that houses the catalyst carrier, and a holding material that is attached to the catalyst carrier and interposed in a gap between the catalyst carrier and the casing. An aqueous slurry containing at least one of a highly crystallized mullite fiber having a mullite conversion rate of 75 to 90% and a highly crystallized alumina fiber having an α-corundum conversion rate of 30 to 60% is formed into a flat plate or a catalyst support. A method for producing a holding material for a catalytic converter, wherein a molded body is produced by suction dehydration molding in the same shape as the outer shape of the above, and then the molded body is dried.
(10) The above-mentioned aqueous slurry contains at least one of a low crystallization inorganic fiber having a crystallization rate of more than 0 and less than 10% and an amorphous inorganic fiber having a crystallization rate of 0%. The manufacturing method of the holding | maintenance material for catalytic converters as described in (9).
(11) preparing a plurality of aqueous slurries having different solid content concentrations of at least one of the highly crystallized mullite fiber and the highly crystallized alumina fiber, and at least one of the low crystallize inorganic fiber and the amorphous inorganic fiber. The above-mentioned (10), wherein the molded body is produced by performing suction dehydration molding in multiple stages in the order of an aqueous slurry having a high solid content concentration to an aqueous slurry having a low solid content concentration, and then drying the molded body. ) Or the method for producing a holding material for a catalytic converter according to (11).
(12) preparing a plurality of aqueous slurries having different weight ratios of at least one of the highly crystallized mullite fiber and the highly crystallized alumina fiber and at least one of the low crystallized inorganic fiber and the amorphous inorganic fiber; , By carrying out suction dehydration molding using an aqueous slurry of a first weight ratio to produce a molded body, placing the molded body in an aqueous slurry of a second weight ratio and performing suction dehydration molding repeatedly. The method for producing a holding material for a catalytic converter as described in (10) or (11) above.
(13) The method for producing a holding material for a catalytic converter as described in any one of (9) to (12) above, wherein the surface of the molded article after drying is calcined at 700 ° C.
(14) A method for producing the holding material in a catalytic converter comprising a catalyst carrier, a casing accommodating the catalyst carrier, and a holding material mounted on the catalyst carrier and interposed in a gap between the catalyst carrier and the casing. And at least one of a highly crystallized mullite fiber having a mullite conversion rate of 75 to 90% and a highly crystallized alumina fiber having an α-corundum conversion rate of 30 to 60%, or the low crystallization inorganic fiber and the non-crystallization A method for producing a holding material for a catalytic converter, wherein a mixture obtained by adding at least one of crystalline inorganic fibers and dry-mixing is assembled to a predetermined thickness and then subjected to needle punching.
(15) A catalytic converter comprising a catalyst carrier, a casing that accommodates the catalyst carrier, and a holding material that is attached to the catalyst carrier and interposed in a gap between the catalyst carrier and the casing, wherein the holding material is A catalytic converter comprising the holding material according to any one of (1) to (8) above.

本発明の触媒コンバーター用保持材は、含有する高結晶化繊維が結晶化の過程で引き起こる繊維のクリープ現象を起こさないため、１２００℃といった超高温においても、優れた触媒担体保持性能及び排気ガスシール性能を維持することができ、触媒コンバーターの耐熱性の向上、長寿命化を図ることが可能である。 The holding material for the catalytic converter of the present invention does not cause the fiber creep phenomenon caused by the highly crystallized fibers contained in the crystallization process, so that the catalyst carrier holding performance and the exhaust gas are excellent even at an extremely high temperature of 1200 ° C. The sealing performance can be maintained, and the heat resistance and the life of the catalytic converter can be improved.

以下に本発明に関して詳細に説明する。 The present invention will be described in detail below.

図１は、本発明の触媒コンバーター用保持材（以下、単に「保持材」という）を装着した触媒コンバーターの一例を模式的に示す断面図であるが、本発明の保持材３も、従来と同様に触媒担体１に巻装されてケーシング２との間隙に介装される。但し、本発明に係る保持材３は下記に示す特定の無機繊維で構成される。 FIG. 1 is a cross-sectional view schematically showing an example of a catalytic converter equipped with a holding material for a catalytic converter of the present invention (hereinafter simply referred to as “holding material”). Similarly, it is wound around the catalyst carrier 1 and interposed in the gap with the casing 2. However, the holding material 3 according to the present invention is composed of the following specific inorganic fibers.

尚、保持材３の形状は、フラットなマット状とすることができるが、触媒担体１の外形形状（ここでは円筒状）に合わせて成形することにより、触媒担体１にそのまま装着することができ、触媒コンバーターの製造を容易できる。 The shape of the holding material 3 can be a flat mat shape, but it can be mounted on the catalyst carrier 1 as it is by forming it in accordance with the outer shape of the catalyst carrier 1 (here, a cylindrical shape). The catalytic converter can be easily manufactured.

本発明の保持材３は、ムライト化率が７５〜９０％の高結晶化ムライト繊維、α−コランダム化率が３０〜６０％である高結晶化アルミナ繊維を含む。これらの高結晶化繊維はそれぞれ単独でも、混合して使用してもよい。ここで、ムライト化率７５〜９０％とは、ムライト繊維を１５００℃で３時間加熱処理して完全に結晶化させたムライト繊維におけるムライトの生成割合を１００とし、それに対する相対値である。同様に、α−コランダム化率３０〜６０％とは、アルミナ繊維を１５００℃で３時間加熱処理して完全に結晶化させたアルミナ繊維におけるα−コランダムの生成割合を１００とし、それに対する相対値である。また、このムライト化率及びα−コランダム化率は、Ｘ線回折法により求めることができる。 The holding material 3 of the present invention includes highly crystallized mullite fibers having a mullite conversion rate of 75 to 90% and highly crystallized alumina fibers having an α-corundum conversion rate of 30 to 60%. These highly crystallized fibers may be used alone or in combination. Here, the mullite conversion rate of 75 to 90% is a relative value with respect to 100 as the mullite generation ratio in the mullite fiber obtained by heat-treating the mullite fiber at 1500 ° C. for 3 hours to completely crystallize it. Similarly, the α-corundum conversion rate of 30 to 60% means that the production rate of α-corundum in the alumina fiber obtained by heat-treating the alumina fiber at 1500 ° C. for 3 hours to be completely crystallized is 100, and the relative value to it. It is. Further, the mullite conversion rate and α-corundum conversion rate can be obtained by an X-ray diffraction method.

また、このような結晶化度のアルミナ繊維及びムライト繊維は、共に従来から保持材に使用されているものを適宜選択して加熱処理して結晶化させたものである。このときの加熱条件により、結晶化度が調整できる。アルミナ繊維としては、例えばＡｌ₂Ｏ₃分が９０重量％以上（残りはＳｉＯ₂分）で、平均繊維径が３〜７μｍ、ウエットボリューム４００〜１０００ｃｃ／５ｇのものが適当である。また、ムライト繊維としては、Ａｌ₂Ｏ₃分／ＳｉＯ₂分重量比が７２／２８〜８０／２０のムライト組成を有し、平均繊維径が３〜７μｍで、ウエットボリューム４００〜１０００ｃｃ／５ｇのものが適当である。 Moreover, both the alumina fiber and the mullite fiber having such a crystallinity are those appropriately selected from those conventionally used for holding materials and crystallized by heat treatment. The crystallinity can be adjusted by the heating conditions at this time. As the alumina fiber, for example, an Al ₂ O ₃ content of 90% by weight or more (the rest is SiO ₂ ), an average fiber diameter of 3 to 7 μm, and a wet volume of 400 to 1000 cc / 5 g is suitable. The mullite fiber has a mullite composition with an Al ₂ O ₃ minute / SiO ₂ minute weight ratio of 72/28 to 80/20, an average fiber diameter of 3 to 7 μm, and a wet volume of 400 to 1000 cc / 5 g. Things are appropriate.

尚、上記ウエットボリュームは、次の方法で算出される。
１）乾燥した繊維材料５ｇを少数点２桁以上の精度を有する秤で計量する。
２）計量した繊維材料を５００ｇのガラスビーカーに入れる。
３）２）のガラスビーカーに温度２０〜２５℃の蒸留水を４００ｃｃ程度入れ、攪拌機を用いて繊維材料を切断しないように慎重に攪拌し、分散させる。この分散は超音波洗浄機を使用してもよい。
４）３）のガラスビーカーの中味を１０００ｍｌのメスシリンダーに移し、目盛で１０００ｃｃまで蒸留水を加える。
５）４）のメスシリンダーの口を手等で塞ぎ、水が漏れないように注意しながら上下逆さまにして攪拌する。これを計１０回繰り返す。
６）攪拌停止後、室温下で静置し、３０分経過後の繊維沈降体積を目視で計測する。
７）上記操作を３サンプルについて行い、その平均値を測定値とする The wet volume is calculated by the following method.
1) Weigh 5 g of dried fiber material with a scale having an accuracy of two decimal places or more.
2) Place the weighed fiber material into a 500 g glass beaker.
3) About 400 cc of distilled water having a temperature of 20 to 25 ° C. is placed in the glass beaker of 2), and carefully stirred and dispersed using a stirrer so as not to cut the fiber material. An ultrasonic cleaner may be used for this dispersion.
4) Transfer the contents of the glass beaker of 3) to a 1000 ml graduated cylinder and add distilled water to a scale of 1000 cc.
5) Close the mouth of the graduated cylinder of 4) with your hands, and stir it upside down, taking care not to leak water. This is repeated a total of 10 times.
6) After the stirring is stopped, the mixture is allowed to stand at room temperature, and the fiber sedimentation volume after 30 minutes has been visually measured.
7) Perform the above operation for 3 samples and use the average value as the measured value.

このような高結晶化無機繊維を用いることにより、保持材が使用中に１２００℃程度の高温に晒されたとしても、更なる結晶化の進行が起こらず、保持材の１２００℃における圧縮復元荷重が０Ｎ／ｃｍ²を越え、より好ましくは１Ｎ／ｃｍ²を越え、更に好ましくは３Ｎ／ｃｍ²を越えることができ、保持力を維持することができる。 By using such highly crystallized inorganic fiber, even if the holding material is exposed to a high temperature of about 1200 ° C. during use, further crystallization does not occur, and the compression restoring load of the holding material at 1200 ° C. There beyond 0N / cm ^2, more preferred more than 1N / cm ^2, more preferably can cross 3N / cm ^2, it is possible to maintain the holding force.

本発明においては、上記の高結晶化繊維に、結晶化率が０を超え１０％未満である低結晶化無機繊維を配合してもよい。上記のように、低結晶化無機繊維は柔軟性を備えるため、触媒担体への装着性が向上する。低結晶化無機繊維としては、このような結晶化度に調整したアルミナ繊維、シリカ繊維等が挙げられる。 In the present invention, low crystallized inorganic fibers having a crystallization rate of more than 0 and less than 10% may be blended with the above highly crystallized fibers. As described above, since the low crystallized inorganic fiber has flexibility, the mounting property to the catalyst carrier is improved. Examples of the low crystallized inorganic fibers include alumina fibers and silica fibers adjusted to such crystallinity.

また、上記の低結晶化無機繊維に代えて、あるいは、低結晶化無機繊維と併用して、結晶化率が０％である非晶質無機繊維を配合してもよい。これにより、触媒担体への装着性が更に向上する。 Further, instead of the above low-crystallized inorganic fiber, or in combination with the low-crystallize inorganic fiber, an amorphous inorganic fiber having a crystallization rate of 0% may be blended. Thereby, the mounting property to the catalyst carrier is further improved.

高結晶化無機繊維と、低結晶化無機繊維及び非晶質無機繊維の少なくとも一方との重量比率は、高結晶化無機繊維：低結晶化無機繊鮭及び非晶質無機繊維の少なくとも一方＝１０：９０〜９０：１０が好ましく、５０：５０〜７０：３０であることがより好ましい。高結晶化無機繊維が少なすぎると期待する十分な耐熱性が得られず、低結晶化無機繊維及び非晶質無機繊維の少なくとも一方が少なすぎると期待する十分な柔軟性が得られない。 The weight ratio between the highly crystallized inorganic fiber and at least one of the low crystallized inorganic fiber and the amorphous inorganic fiber is high crystallized inorganic fiber: at least one of the low crystallized inorganic fiber and the amorphous inorganic fiber = 10. : 90-90: 10 is preferable, and it is more preferable that it is 50: 50-70: 30. If the amount of highly crystallized inorganic fibers is too small, sufficient heat resistance expected cannot be obtained, and sufficient flexibility expected when at least one of the low crystallized inorganic fibers and amorphous inorganic fibers is too small cannot be obtained.

保持材とするには、高結晶化無機繊維、あるいは高結晶化無機繊維と、低結晶化無機繊維及び非晶質無機繊維の少なくとも一方とをミキサ等により乾式で混合して混合物とし、それぞれを所定厚に集成して成形体とすればよい。得られる保持材は、繊維の結晶化が保持材全体で起こることがなく、安定して触媒担体を保持できるという効果が期待できる。また、集成後、成形体にニードルパンチング処理を施しても良く、これにより熱膨張によるケーシングや触媒担体のギャップ変動から考えられる保持材の繰り返し圧縮による繊維崩れを防ぐ効果が期待できる。 For the holding material, highly crystallized inorganic fibers or highly crystallized inorganic fibers and at least one of low crystallized inorganic fibers and amorphous inorganic fibers are mixed by a dry method using a mixer or the like to form a mixture. What is necessary is just to assemble | stack to a predetermined thickness and to make a molded object. The obtained holding material can be expected to have an effect that the catalyst carrier can be stably held without causing crystallization of the fiber throughout the holding material. Further, after assembling, the molded body may be subjected to a needle punching process, which can be expected to prevent fiber collapse due to repeated compression of the holding material, which is considered from a gap variation between the casing and the catalyst carrier due to thermal expansion.

また、吸引脱水成形を行うこともでき、高結晶化無機繊維を含む水性スラリー、あるいは更に低結晶化無機繊維及び非結晶化無機繊維の少なくとも一方を添加した水性スラリーに、例えば金属製のメッシュ平板あるいはこれを円筒状に成形した抄造型を配置して吸引脱水する。そして、成形体を乾燥して保持材が得られる。 Further, suction dehydration molding can also be performed. For example, a metal mesh flat plate is added to an aqueous slurry containing highly crystallized inorganic fibers or an aqueous slurry to which at least one of low crystallized inorganic fibers and non-crystallized inorganic fibers is added. Alternatively, a papermaking mold formed into a cylindrical shape is placed and suction dehydrated. Then, the molded body is dried to obtain a holding material.

水性スラリーには、有機バインダーを添加してもよい。有機バインダーは、公知のもので構わず、ゴム類、水溶性有機高分子化合物、熱可塑性樹脂、熱硬化性樹脂、有機繊維等を使用できる。具体的には、ゴム類の例としては、ｎ−ブチルアクリレートとアクリロニトリルの共重合体、エチルアクリレートとアクリロニトリルの共重合体、ブタジエンとアクリロニトリルの共重合体、ブタジエンゴム等がある。水溶性有機高分子化合物の例としては、カルボキシメチルセルロース、ポリビニルアルコール等がある。熱可塑性樹脂の例としては、アクリル酸、アクリル酸エステル、アクリルアミド、アクリロニトリル、メタクリル酸、メタクリル酸エステル等の単独重合体及び共重合体、アクリロニトリル・スチレン共重合体、アクリロニトリル・ブタジエン・スチレン共重合体等がある。熱硬化性樹脂としては、ビスフェノール型エポキシ樹脂、ノボラック型エポキシ樹脂等がある。有機繊維としては、ポリビニルアルコール繊維、バルプ、レーヨン繊維等が挙げられる。本発明においては、特に上述した有機バインダーを使用した場合、得られる保持材に柔軟性が付与され、触媒担体への装着作業が容易になる。有機バインダーの使用量は、保持材に柔軟性を得えられる量であれば制限ないが、上記の高結晶化無機繊維１００重量部に対して最大でも２０重量部に留めることが好ましい。有機バインダーが２０重量部を越える場合は、運転初期にＣＯ₂やＣＯ、各種の有機系ガスが多量に発生して保持材中に空隙が生成し、保持力を低下させるおそれがある。 An organic binder may be added to the aqueous slurry. The organic binder may be a known one, and rubbers, water-soluble organic polymer compounds, thermoplastic resins, thermosetting resins, organic fibers, and the like can be used. Specifically, examples of rubbers include a copolymer of n-butyl acrylate and acrylonitrile, a copolymer of ethyl acrylate and acrylonitrile, a copolymer of butadiene and acrylonitrile, and butadiene rubber. Examples of the water-soluble organic polymer compound include carboxymethyl cellulose and polyvinyl alcohol. Examples of thermoplastic resins include acrylic acid, acrylic acid ester, acrylamide, acrylonitrile, methacrylic acid, methacrylic acid ester homopolymers and copolymers, acrylonitrile / styrene copolymer, acrylonitrile / butadiene / styrene copolymer Etc. Examples of the thermosetting resin include a bisphenol type epoxy resin and a novolac type epoxy resin. Examples of the organic fiber include polyvinyl alcohol fiber, valve, rayon fiber and the like. In the present invention, in particular, when the organic binder described above is used, flexibility is imparted to the obtained holding material, and the mounting work on the catalyst carrier is facilitated. The amount of the organic binder used is not limited as long as the holding material can obtain flexibility. However, it is preferable that the amount of the organic binder is limited to 20 parts by weight at the maximum with respect to 100 parts by weight of the highly crystallized inorganic fibers. When the organic binder exceeds 20 parts by weight, a large amount of CO ₂ , CO, and various organic gases are generated in the initial stage of operation and voids are generated in the holding material, which may reduce the holding power.

また、予め保持材から上記の有機系ガスを除去しておくことも好ましく、乾燥後の成形体の触媒担体と接する側の面を、有機系ガスが揮散する７００℃で加熱処理する。 In addition, it is also preferable to remove the organic gas from the holding material in advance, and the surface on the side in contact with the catalyst carrier of the dried molded body is heat-treated at 700 ° C. where the organic gas is volatilized.

本発明の保持材は、上記のように、全体が均一な組成であってもよいし、厚さ方向に組成が変化する傾斜組成構造であってもよい。具体的には、触媒担体と接する面に高結晶化無機繊維が多く含まれる構成とすることで、耐熱性と柔軟性とを兼備する保持材が得られる。 As described above, the holding material of the present invention may have a uniform composition as a whole, or may have a gradient composition structure in which the composition changes in the thickness direction. Specifically, a holding material having both heat resistance and flexibility can be obtained by adopting a configuration in which a large amount of highly crystallized inorganic fibers are included in the surface in contact with the catalyst carrier.

このような傾斜組成構造の保持材を得るには、それぞれ組成の異なる成形体を作製し、積層すればよい。また、吸引脱水成形の際に、高結晶化無機繊維、低結晶化無機繊維及び非晶質無機繊維の少なくとも一方の固形分濃度の異なる複数の水性スラリーを用い、先ず固形分濃度の最も高い水性スラリーにて吸引脱水成形を行って成形体を作製し、次いで、この成形体を２番目に固形分濃度の高い水性スラリーに配置して吸引脱水成形を行い、２層構造の成形体を作製し、順次、固形分濃度の高い水性スラリーから固形分濃度の低い水性スラリーへと移行して吸引脱水成形を多段に行うこともできる。更に、吸引脱水成形の際に、高結晶化無機繊維と、低結晶化無機繊維及び非晶質無機繊維の少なくとも一方との重量比率が異なる複数の水性スラリーを用い、先ず高結晶化無機繊維の固形分濃度の最も高い水性スラリーにて吸引脱水成形を行って成形体を作製し、次いで、この成形体を２番目に高結晶化無機繊維の固形分濃度の高い水性スラリーに配置して吸引脱水成形を行い、２層構造の成形体を作製し、順次、高結晶化無機繊維の固形分濃度の高い水性スラリーから高結晶化無機繊維の固形分濃度の低い水性スラリーへと移行して吸引脱水成形を多段に行ってもよい。 In order to obtain a holding material having such a gradient composition structure, molded bodies having different compositions may be prepared and laminated. In addition, at the time of suction dehydration molding, a plurality of aqueous slurries having different solid content concentrations of at least one of highly crystallized inorganic fibers, low crystallized inorganic fibers and amorphous inorganic fibers are used. A molded product is produced by performing suction dehydration molding with a slurry, and then the molded product is placed in an aqueous slurry having the second highest solid content concentration and subjected to suction dehydration molding to produce a molded product having a two-layer structure. Then, it is possible to carry out suction dehydration molding in multiple stages by sequentially shifting from an aqueous slurry having a high solid content concentration to an aqueous slurry having a low solid content concentration. Furthermore, at the time of suction dehydration molding, a plurality of aqueous slurries having different weight ratios of the highly crystallized inorganic fiber and at least one of the low crystallized inorganic fiber and the amorphous inorganic fiber are used. Suction dehydration molding is performed with the aqueous slurry having the highest solid content concentration to produce a molded body, and then this molded body is placed in the aqueous slurry with the second highest solid content concentration of highly crystallized inorganic fibers to perform suction dehydration. Molding is performed to produce a two-layered molded body, which is sequentially transferred from an aqueous slurry having a high solid content concentration of highly crystallized inorganic fibers to an aqueous slurry having a low solid content concentration of highly crystallized inorganic fibers, and suction dewatering. Molding may be performed in multiple stages.

尚、本発明において、保持材の装着時の密度や厚さは、適用する触媒コンバーターのサイズや使用温度等に応じて適宜設定することができるが、密度については通常は０．２〜０．６ｇ／ｍ³の範囲であり、本発明においても同様にすることができる。 In the present invention, the density and thickness at the time of mounting the holding material can be appropriately set according to the size of the catalytic converter to be applied, the operating temperature, etc., but the density is usually 0.2 to 0. The range is 6 g / m ³ , and the same can be applied in the present invention.

以下、実施例及び比較例を挙げて本発明をさらに具体的に説明するが、本発明はこれにより何ら限定されるものではない。 EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated further more concretely, this invention is not limited at all by this.

〔実施例１〕
平均繊維径４．０μｍ、ウエットボリューム６００ｃｃ／５ｇの低結晶アルミナ繊維６０重量部と、平均繊維径５．０μｍ、ウエットボリューム７００ｃｃ／５ｇの高結晶化度ムライト繊維４０重量部とを水中で混合し、これにアクリルエマルジョンを１０重量部加えて水性スラリーを調製した。そして、この水性スラリーを２００メッシュのステンレス製の長方体状金網を用いて吸引脱水してマット状の成形体を作製し、この成形体を１０５℃で加熱乾燥して、長さ３３０ｍｍ、厚さ７ｍｍ、幅１００ｍｍで重量５１ｇのマット状の保持材を得た。 [Example 1]
60 parts by weight of low-crystal alumina fibers having an average fiber diameter of 4.0 μm and a wet volume of 600 cc / 5 g and 40 parts by weight of high crystallinity mullite fibers having an average fiber diameter of 5.0 μm and a wet volume of 700 cc / 5 g are mixed in water. An aqueous slurry was prepared by adding 10 parts by weight of an acrylic emulsion. The aqueous slurry was sucked and dehydrated using a 200-mesh stainless steel rectangular wire net to produce a mat-like molded body, and the molded body was heat-dried at 105 ° C. to obtain a length of 330 mm and a thickness of A mat-like holding material having a thickness of 7 mm, a width of 100 mm and a weight of 51 g was obtained.

〔比較例１〕
平均繊維径５．０μｍ、ウエットボリューム７００ｃｃ／５ｇの低結晶ムライト繊維１００重量部と、アクリルエマルジョン１０重量部とを含む水性スラリーを調製した。そして、この水性スラリーを２００メッシュのステンレス製の長方体状金網を用いて吸引脱水してマット状の成形体を作製し、この成形体を１０５℃で加熱乾燥して、長さ３３０ｍｍ、厚さ７ｍｍ、幅１００ｍｍで重量５１ｇのマット状の保持材を得た。 [Comparative Example 1]
An aqueous slurry containing 100 parts by weight of low crystalline mullite fibers having an average fiber diameter of 5.0 μm and a wet volume of 700 cc / 5 g and 10 parts by weight of an acrylic emulsion was prepared. The aqueous slurry was sucked and dehydrated using a 200-mesh stainless steel rectangular wire net to produce a mat-like molded body, and the molded body was heat-dried at 105 ° C. to obtain a length of 330 mm and a thickness of A mat-like holding material having a thickness of 7 mm, a width of 100 mm and a weight of 51 g was obtained.

（圧縮復元荷重測定試験）
各保持材を７００℃で１時間加熱して有機バインダーを除去した後、極超高温材料試験機（ＭＴＳジャパン製「８０８型」）を用いて、圧縮（ギャップ：４ｍｍ）したまま１２００℃まで加熱し、圧縮復元荷重測定試験を行った。 (Compression restoration load measurement test)
Each holding material is heated at 700 ° C. for 1 hour to remove the organic binder, and then heated to 1200 ° C. while being compressed (gap: 4 mm) using an ultra-high temperature material testing machine (“808 type” manufactured by MTS Japan). Then, a compression restoring load measurement test was conducted.

実施例１の保持材では、１０００℃以上からある程度の荷重の低下が見られたが、１２００℃でも復元荷重が認められたのに対し、比較例１の保持材では１０００℃で面圧が低下し、１２００℃では数分程度で復元荷重が０になった。 In the holding material of Example 1, a certain amount of load decrease was observed from 1000 ° C. or higher, but a restoring load was observed even at 1200 ° C., whereas in the holding material of Comparative Example 1, the surface pressure decreased at 1000 ° C. At 1200 ° C., the restoring load became zero in about several minutes.

（実装試験）
実施例１及び比較例１で得られた各保持材を、外径１００ｍｍ、長さ１１０ｍｍの円筒状ハニカム構造のコージェライト製触媒担体に巻装し、ステンレス製ケーシングに装着して触媒コンバーターを作製した。そして、作製した各触媒コンバーターをガソリンエンジンの排気管に接続し、２４時間連続して１１００℃の排気ガスを通過させた。排気ガスの通過中、各触媒コンバーターから排出されるガスを分析した。 (Mounting test)
Each holding material obtained in Example 1 and Comparative Example 1 was wound around a cordierite catalyst carrier having a cylindrical honeycomb structure having an outer diameter of 100 mm and a length of 110 mm, and mounted on a stainless steel casing to produce a catalytic converter. did. Each of the produced catalytic converters was connected to an exhaust pipe of a gasoline engine, and exhaust gas at 1100 ° C. was allowed to pass through for 24 hours. During the passage of the exhaust gas, the gas discharged from each catalytic converter was analyzed.

実施例１の保持材を装着した触媒コンバーターは安定した浄化作用を示し、シール性能も長期間維持されていたのに対し、比較例１の保持材を装着した触媒コンバーターでは、ガスの通過を続けたところ、排気ガスの漏れが認められ、触媒コンバーターを分解したところ、保持材が作製当初の装着位置から大きくずれていた。 The catalytic converter equipped with the holding material of Example 1 showed a stable purification action and the sealing performance was maintained for a long time, whereas the catalytic converter equipped with the holding material of Comparative Example 1 continued to pass gas. As a result, leakage of exhaust gas was observed, and when the catalytic converter was disassembled, the holding material was significantly displaced from the initial mounting position.

触媒コンバーターを模式的に示す断面図である。It is sectional drawing which shows a catalytic converter typically.

Explanation of symbols

１触媒担体
２ケーシング
３保持材 1 Catalyst carrier 2 Casing 3 Holding material

Claims

The holding material in a catalytic converter comprising a catalyst carrier, a casing for housing the catalyst carrier, and a holding material mounted on the catalyst carrier and interposed in a gap between the catalyst carrier and the casing. A holding material for a catalytic converter, comprising at least one of highly crystallized mullite fibers having a ratio of 75 to 90% and highly crystallized alumina fibers having an α-corundum ratio of 30 to 60%.

The holding material for a catalytic converter according to claim 1, wherein a compression recovery load at 1200 ° C exceeds 0 N / cm ² .

3. The holding material for a catalytic converter according to claim 1 or 2, comprising low-crystallized inorganic fibers having a crystallization rate of more than 0 and less than 10%.

The holding material for a catalytic converter according to any one of claims 1 to 3, comprising amorphous inorganic fibers having a crystallization rate of 0%.

5. The holding material for a catalytic converter according to claim 3, wherein at least one of the low crystallized inorganic fiber and the amorphous inorganic fiber is contained in an amount of 10 to 90% by mass based on the total amount of the fiber.

A mixture of at least one of the highly crystallized mullite fiber and the highly crystallized alumina fiber and at least one of the low crystallize inorganic fiber and the amorphous inorganic fiber is assembled to a predetermined thickness. The holding | maintenance material for catalytic converters in any one of Claims 3-5.

The holding material for a catalytic converter according to any one of claims 3 to 6, wherein at least two layers having different compositions are laminated.

The content of at least one of the highly crystallized mullite fiber and the highly crystallized alumina fiber is highest on the surface in contact with the catalyst carrier and gradually decreases toward the inside. The holding | maintenance material for catalytic converters of Claim 1.

A method for producing the holding material in a catalytic converter comprising a catalyst carrier, a casing that houses the catalyst carrier, and a holding material that is mounted on the catalyst carrier and interposed in a gap between the catalyst carrier and the casing, An aqueous slurry containing at least one of a highly crystallized mullite fiber having a mullite conversion rate of 75 to 90% and a highly crystallized alumina fiber having an α-corundum conversion rate of 30 to 60% is formed into a flat plate shape or an outer shape of a catalyst support. A method for producing a holding material for a catalytic converter, wherein the molded body is produced by suction dehydration molding in the same manner as described above, and then the molded body is dried.

10. The aqueous slurry contains at least one of a low crystallization inorganic fiber having a crystallization rate of more than 0 and less than 10% and an amorphous inorganic fiber having a crystallization rate of 0%. The manufacturing method of the holding | maintenance material for catalytic converters of description.

Preparing at least one of the highly crystallized mullite fiber and the highly crystallized alumina fiber, and a plurality of aqueous slurries having different solid content concentrations of at least one of the low crystallized inorganic fiber and the amorphous inorganic fiber; The method according to claim 10 or 11, wherein the molded body is produced by performing suction dehydration molding in multiple stages in the order of the aqueous slurry having a high concentration to the aqueous slurry having a low solid content concentration, and then drying the molded body. The manufacturing method of the holding | maintenance material for catalytic converters of description.

Preparing a plurality of aqueous slurries having different weight ratios of at least one of the highly crystallized mullite fiber and the highly crystallized alumina fiber and at least one of the low crystallized inorganic fiber and the amorphous inorganic fiber; A molded product is produced by suction dehydration molding using an aqueous slurry having a weight ratio of 2 to 5, and an operation of placing the molded body in an aqueous slurry having a second weight ratio and performing suction dehydration molding is repeated. The manufacturing method of the holding | maintenance material for catalytic converters of Claim 10 or 11.

The method for producing a holding material for a catalytic converter according to any one of claims 9 to 12, wherein the surface of the molded article after drying is calcined at 700 ° C.

A method for producing the holding material in a catalytic converter comprising a catalyst carrier, a casing that houses the catalyst carrier, and a holding material that is mounted on the catalyst carrier and interposed in a gap between the catalyst carrier and the casing, At least one of a highly crystallized mullite fiber having a mullite conversion rate of 75 to 90% and a highly crystallized alumina fiber having an α-corundum conversion rate of 30 to 60%, or the low crystallized inorganic fiber and the amorphous inorganic A method for producing a holding material for a catalytic converter, wherein a mixture obtained by adding at least one of fibers and dry-mixing is assembled to a predetermined thickness and then subjected to needle punching.

2. A catalytic converter comprising a catalyst carrier, a casing for accommodating the catalyst carrier, and a holding material mounted on the catalyst carrier and interposed in a gap between the catalyst carrier and the casing, wherein the holding material is the catalyst converter. A catalytic converter comprising the holding material according to any one of -8.