DE102008012643A1 - Coating internal surface of molded article for contacting with flow-through fluid, comprises inserting the article, which comprises first and second front surfaces, into lockable container, and contacting second surface with coating fluid - Google Patents

Abstract

The method for coating internal surface of a molded article (8) for contacting with a flow-through fluid, comprises inserting the article, which comprises a first (12) and a second front surface (13), into a lockable container, where a first chamber (2) is formed with an adjustable first pressure and a second chamber (4) is formed with a second pressure, contacting the second front surface of the molded article with a fluid (10) provided for coating, where the molded article is present itself in the second chamber, and adjusting the second pressure in the second chamber. The method for coating internal surface of a molded article (8) for contacting with a flow-through fluid, comprises inserting the article, which comprises a first (12) and a second front surface (13), into a lockable container, where a first chamber (2) is formed with an adjustable first pressure and a second chamber (4) is formed with a second pressure adjustable independently from the first pressure after insertion of the molded article and locking of the container, contacting the second front surface of the molded article with a fluid (10) provided for coating where the molded article is present itself in the second chamber, and adjusting the second pressure in the second chamber so that the second pressure is greater than the first pressure in the first chamber and the difference of pressure is sufficient in order to flow the fluid for coating through the molded article. The molded article is inserted in such a way that a fluid of the second chamber flows through the molded article to the first chamber. The coating fluid flows through the molded article to a first pre-determined value and then the second front surface is separated from the coating fluid and the second pressure in the second chamber is kept at a value above the first pressure in the first chamber until the coating fluid present in the molded article is passed to a second pre-determined value. The coating fluid in the second chamber is supplied into a further container and the distance of the further container to the molded article is changeable on a control instruction. The flow of coating fluid is measured by a time-of-flight camera, by a Roentgen camera, by determination of the acoustic resonance of the gas column, by electrical conductivity measurements and/or by electrical resistance tests. The first pressure in the first chamber and/or the second pressure in the second chamber oscillate around a pre-determined value. The fluid front of the fluid is subjected with sound waves during its passage through the molded article. The second pressure in the second chamber is adjusted to a pre-determined time in such a way that the second pressure is smaller than the first pressure in the first chamber and the difference of pressure (0.01-10%) is sufficient, in order to flow the fluid intended for coating against the previous direction of flow. An independent claim is included for a device for the coating of the internal surface of a molded article.

Description

The The present invention relates to a method for coating the inner surface of a shaped body, wherein the Shaped body in a sealable container is used and after closing the container within the container a first chamber with an adjustable first pressure and a second chamber with one independent of the first pressure adjustable second pressure to be formed. The molded body is used here so that a fluid from the second chamber flow through the molded body to the first chamber can. The present invention further relates to a device for coating the inner surface of a shaped body, comprising a through a gas impermeable first wall formed first chamber and one through a gas impermeable second wall formed second chamber. Between the first and the second chamber is arranged a partition, which is a continuous Having recess for receiving a shaped body.

State of the art

In today's technology for the aftertreatment of exhaust gases from internal combustion engines, honeycomb ceramic bodies, for example made of cordierite, mullite or SiC, are used. In addition to the round cylindrical shape, these shaped bodies can also have angular and oval cross sections. For use as three-way catalysts (TWC) and diesel oxidation catalysts usually flow bodies are used. This also applies to catalysts for selective catalytic reduction (SCR) or catalysts for the storage of NO _x (NO _x storage catalysts, NSC). In diesel particle filters (DPF), the channels are mutually closed, creating a wall flow body.

The Shaped bodies are used for the corresponding function coated. The coating can have a catalytic function for Have implementation or storage of noxious gases. In the case of catalytic coatings These coatings are called washcoat. These include For example, TWC coatings, DOC coatings (diesel oxidation Catalyst; Diesel oxidation catalyst), NSC coatings or SCR coatings. Diesel particle filters are also coated used. The catalytically active coating causes harmful gases saved and implemented. The reaction heat occurring here contributes to achieving the necessary for the regeneration of the filter Exhaust gas temperature at.

The Coating of the substrates can also be the function of a protective layer have or increase the mechanical or thermochemical Contribute to stability. To carry out the coating the coating components are in the form of a dispersion or Solution applied. These are deposited in or on the porous Structure of the ceramic body from. By a thermal Process, the fixation of the components. This type of coating comes in both flow-through substrates and wall-flow substrates, So generally in so-called honeycomb substrates used.

WO 99/47260 A1 discloses an apparatus for coating a support, such as a monolithic catalyst support. This device comprises a metering device for a predetermined amount of a coating liquid, a container for the coating liquid and a vacuum source. The vacuum source can be driven to draw the entire amount of coating liquid into the carrier.

at known coating methods are partially over the substrates coated their entire volume or the complete cross section. In general, by the conventional coating method axial gradients in the amount of coating agent and thus reaches the catalytically active substances. Continue to miss take precautions when aspirating the coating composition, to the penetration of coating material in the vacuum apparatus to prevent. Likewise, when applying vacuum the penetration of coating material into the molding partially inaccurate control. For example, local Constrictions within the porous interior of the molding cause that in the flow direction behind the blockage legend uncoated areas occur which are not covered by the Covered around the constriction flowing coating become. Finally, known methods do not disclose how to work in a controlled atmosphere can, for example, when the catalyst precursor oxidation sensitive is and must be worked under inert gas.

Disclosure of the invention

• (a) Einsetzen des Formkörpers in einen verschließbaren Behälter, wobei nach dem Einsetzen des Formkörpers und dem Verschließen des Behälters innerhalb des Behälters eine erste Kammer mit einem einstellbaren ersten Druck und eine zweite Kammer mit einem vom ersten Druck unabhängig einstellbaren zweiten Druck ausgebildet werden und wobei der Formkörper so eingesetzt wird, dass ein Fluid von der zweiten Kammer durch den Formkörper hindurch zu der ersten Kammer strömen kann;
• (b) Kontaktieren der zweiten Stirnfläche des Formkörpers, welche sich in der zweiten Kammer des Behälters befindet, mit einem zur Beschichtung vorgesehenen Fluid;
• (c) Einstellen des zweiten Drucks in der zweiten Kammer des Behälters, so dass der zweite Druck größer als der erste Druck in der ersten Kammer des Behälters ist und wobei die Druckdifferenz ausreichend ist, um das zur Beschichtung vorgesehene Fluid durch den Formkörper strömen zu lassen.

According to the invention, a method is proposed for coating the inner surface of a shaped body, wherein the inner surface of the shaped body is suitable for contacting with a fluid flowing through, and wherein the shaped body has a first end face and a second end face, comprising the steps:

• (A) inserting the molding in a sealable container, wherein after insertion of the molding and the closing of the Be container within the container, a first chamber having an adjustable first pressure and a second chamber are formed with a second pressure independently adjustable from the first pressure and wherein the shaped body is inserted so that a fluid from the second chamber through the molded body to the first chamber can flow;
• (b) contacting the second end surface of the shaped body, which is located in the second chamber of the container, with a fluid intended for coating;
• (c) adjusting the second pressure in the second chamber of the container such that the second pressure is greater than the first pressure in the first chamber of the container and wherein the pressure differential is sufficient to allow the fluid for coating to flow through the shaped body ,

Of the According to the invention coatable molding For example, it can be a porous one or one with channels be provided catalyst support. According to the desired use is provided that a fluid such as Combustion gases or a reaction solution of a chemical Process flow through the molding and thereby overflow the inner surface. At the Flow through this fluid becomes a main flow direction Are defined. This can, for example, along the longitudinal axis be the molding. The first and second end faces of the molding are for the entry and exit of a flowing Fluids suitable. The faces can be vertical to the main flow direction.

To the insertion of the molding and sealing of the container become two inside the container Chambers formed. The container has means to the Pressures in the two chambers to influence separately. In particular, the case is provided that during the Coating, so while intended for coating Fluid is in the molding and the two chambers thereby closed against each other, the pressures separated can be influenced. This can be both to act as an overpressure as well as a negative pressure. The shaped body is thus introduced into the container, that a fluid, so gas or provided for coating Fluid, from one chamber to another through the molding has to flow. As a result, so the pressure difference between the chambers of the container the driving force for the coating of the molding.

The For example, a fluid intended for coating can be a suspension, Emulsion or a solution. In the fluid can catalytically active compounds or their precursor compounds be included. It can be provided that for the coating provided fluid is pumped or stirred to settling of components. So can catalysts with TWC coatings, DOC coatings, NSC coatings or SCR coatings or coated diesel particulate filter obtained become.

Another object of the invention is a device for coating the inner surface of a shaped body comprising a first chamber formed by a gas-impermeable first wall and a second chamber formed by a gas-impermeable second wall;
wherein a partition is disposed between the first and second chambers;
wherein the separation has a continuous recess for receiving a shaped body and the separation is otherwise made gas-impermeable; and
wherein the device is further configured to set a first pressure during coating in the first chamber and a second pressure independently in the second chamber when inserted into the recess molding.

Especially is provided here that the inventive Device forms a container which opened and can be closed again and which the molded body to be coated includes completely.

In the inventive method and the invention Device, it is possible to target in the two chambers create a pressure gradient. This causes fluctuations avoided in the product quality that might otherwise occur if by a change of the atmospheric air pressure during production of a large number of pieces of products of the coating process is affected. Farther can according to the invention the rate of climb and the final rise height of the coating controlled fluid are controlled. Here it is possible Even without manipulation of the molded body, the flow direction reverse.

The Inventive device and the invention Procedures allow it to be independent of the ambient pressure work.

The suppresses inventive method the occurrence of uneven in the longitudinal cross-section Coating profiles in the molding. Furthermore, thanks working in closed chambers in an inert gas atmosphere become. This is especially important when catalyst precursors decompose into coarse-grained aggregates when in contact with air and so during the coating, the interior of a porous Would block moldings.

The The present invention will become apparent from the following drawings further explained. Show it:

1a a device according to the invention without inserted molding

1b a device according to the invention with inserted molding

2a a device according to the invention at the beginning of the inventive method

2 B a device according to the invention during the method according to the invention

2c a device according to the invention at a later time of the method according to the invention

2d a device according to the invention at a later date of the method according to the invention

1a shows a device according to the invention without inserted molding. Part of the device passes through the gas-impermeable first wall 1 educated. Another part is through the gas impermeable second wall 3 educated. The interior of the device is through the gas-impermeable separation 5 divided into two chambers. The first chamber 2 will go outside through the first wall 1 completed, the second chamber 4 through the second wall 3 , The separation 5 has a continuous recess 6 which is suitable for receiving a shaped body. The recess 6 is with a seal 7 Mistake. The gasket may be, for example, a rubber gasket or a polytetrafluoroethylene gasket. Furthermore, the seal may be designed inflatable to allow easier insertion of a shaped body. Not shown are means for pressure adjustment in the two chambers.

1b shows the device 1a , where now the molding 8th in the recess 6 was used. The molded body 8th is due to the seal 7 on, leaving the first chamber 2 and the second chamber 4 are separated from each other and mass transfer between the chambers only through the molding 8th can take place through.

2a - 2d show by way of example various steps of the method according to the invention, which are carried out in a device according to the invention.

2a shows first a container, which outwardly through a first wall 1 and a second wall 3 is completed. The container can be opened and closed again where the first wall 1 and the second wall 3 meet each other. Inside the container is between the first wall 1 and the second wall 3 a separation 5 attached so that within the container a first chamber 2 and a second chamber 4 be formed. A continuous recess in the partition 5 is due to an inserted molding 8th filled. The molded body 8th has a first end face 12 and a second end face 13 on. Between the separation 5 and the shaped body 8th is still seal 7 , In the closed container can now by means not shown for pressure adjustment in the first chamber 2 a first pressure and in the second chamber 4 a second pressure to be built independently. A fluid exchange between the chambers can only by the molding used 8th take place through. The second face 13 of the molding 8th is in 2a not in contact with a fluid intended for coating 10 , The face 13 and the fluid 10 are in the second chamber 4 of the container.

According to one embodiment of the method according to the invention and the device according to the invention, the fluid intended for coating becomes 10 in the second chamber 4 the container in another container 9 provided. The distance of the further container 9 to the molded body 8th is changeable to a control command. In the present case, the distance by means of device 11 set. This can for example be a lift. The drive of the device 11 can be done electrically, hydraulically or pneumatically. As a control command may accordingly act an electrical, hydraulic or pneumatic signal. The control command is triggered on the one hand to the container 9 so that the molded body can be immersed in the coating composition, on the other hand, when the fluid 10 the shaped body 8th has flowed through to a predetermined value. In the illustration according to 2a is the device 11 in a low position, leaving the fluid 10 and the frontal area 13 are not in contact.

2 B shows how the device 11 the distance of the container 9 and thus also the fluid 10 to the face 13 so far reduced that the fluid 10 and the frontal area 13 get in touch with each other.

2c shows how after increasing the second pressure in the second chamber 4 relative to the first pressure in the first chamber 2 the fluid intended for coating 10 through the molding 8th flows. Also shown is the fluid front 14 So the height of rise.

2d further shows an embodiment form of the method according to the invention. In this case, the fluid intended for coating flows through 10 the shaped body 8th to a first predetermined value, after which the second end face 13 of the molding 8th from the one in the second chamber 4 present fluid intended for coating 10 be separated. Furthermore, then the second pressure in the second chamber 4 of the container at a value above the first pressure in the first chamber 2 held the container until that in the molding 8th located intended for coating fluid 10 the shaped body 8th has flowed through to a second predetermined value. Across from 2c became the lifting device 11 lowered, so no fluid 10 more in the moldings 8th can flow. Furthermore, the pressure difference was maintained or increased, so that the height of the fluid front 14 has risen further. An advantage of this embodiment is in particular that an excessive coating in the region of the shaped body 8th is avoided, the first with the fluid 10 comes into contact. This material is namely after the separation of the end face 13 from the one in the chamber 4 or in the container 9 present fluid further into the interior of the molding 8th transported.

In a further embodiment of the method according to the invention, it is further measured how far the fluid intended for coating 10 the shaped body 8th flows through. The measurement can be carried out by means of a runtime camera, by means of an X-ray camera, by determining the acoustic resonance of the gas column above the fluid, by means of electrical conductivity measurements and / or by means of electrical resistance measurements. The determination of the rise height of the fluid 10 By means of a runtime camera or by means of an X-ray camera is advantageous if it is to be measured without contact. In a determination by means of acoustic resonance is in the molding 8th a gas column, in the simplest case an air column, vibrated. Based on the resonance, ie the sound, the expansion of the gas column in the molding can 8th and consequently that already by the fluid 10 occupied volumes are determined. Measurements of the electrical conductivity or the electrical resistance can be realized easily. For example, on the molding 8th attached electrodes at a desired rise height. Once that through the molding 8th flowing fluid 10 reaches the electrodes, a measurable signal is triggered.

In a further embodiment of the method according to the invention, the first pressure in the first chamber oscillate 2 and / or the second pressure in the second chamber 4 by a predetermined value. By this is meant that while the fluid 10 flows through the molding, the first pressure and / or the second pressure oscillate. The oscillation frequency for both pressures can be advantageously independently of one another in a range from ≥ 0.1 Hz to ≦ 100 Hz or preferably from ≥ 1 Hz to ≦ 50 Hz. The oscillation amplitude can be, for example, values from ≥ 0.1% to ≦ 80%, from ≥ 1% to ≦ 50% or from ≥ 3% to ≦ 15%, based on the pressure difference between the chambers. The oscillations lead to a more uniform coating of the molding 10 ,

In a further embodiment of the method according to the invention, the fluid front 14 the fluid intended for coating 10 during the flow through the molding 8th subjected to sound waves. The application is advantageously carried out on the surface of the fluid front 14 , Suitable sound waves in the infrasound, Hörschall- and ultrasonic range. For example, ultrasonic waves with a frequency of ≥ 20 KHz to ≤ 1 GHz can be used. Another possibility is to use sound waves with a frequency of ≥ 1 Hz to ≤ 100 Hz or from ≥ 3 Hz to ≤ 30 Hz. The application of sound waves also leads to a more uniform coating of the molding 8th ,

Another way to achieve a more uniform coating is the molding 8th during the implementation of the method according to the invention into mechanical vibration. In particular, in this case the sedimentation of a suspension during the coating is counteracted. Suitable vibration frequencies may, for example, be in a range from ≥ 1 Hz to ≦ 100 Hz or from ≥ 3 Hz to ≦ 30 Hz.

In a further embodiment of the method according to the invention, the second pressure in the second chamber is at a predetermined time 4 of the container adjusted so that the second pressure is less than the first pressure in the first chamber 3 of the container and that the pressure difference is ≥ 0.01% to ≤ 10%. As a result, first, depending on the viscosity of the fluid, the flow through the fluid 10 through the molding 8th stopped or reversed in the direction, the return flow rate is low. The predetermined time may be, for example, when the fluid 10 the shaped body 8th has flowed through half. Another time may be chosen when the fluid 10 the shaped body 8th has completely flowed through. This will prevent material from the molding 8th exit and get lost. A fluid meniscus, which flows through the molding 8th can be distributed evenly again. The process described can also be repeated several times in succession.

In a further embodiment of the inventions The method according to the invention becomes the second pressure in the second chamber at a predetermined time 4 of the container adjusted so that the second pressure is less than the first pressure in the first chamber 3 the container is and the pressure difference is sufficient to the provided for coating fluid 10 contrary to the previous flow direction through the molding 8th to flow. In this way, a more uniform coating of the shaped body can be achieved. Furthermore, in this way, excess coating material can be recovered when the fluid is discharged or blown out. The pressure difference may be such that the fluid flows back through the action of gravity. However, it can also be dimensioned such that the fluid is actively transported.

QUOTES INCLUDE IN THE DESCRIPTION

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Cited patent literature

• WO 99/47260 A1 [0005]

Claims (10)

Process for coating the inner surface of a molded article ( 8th ), wherein the inner surface of the shaped body ( 8th ) is suitable for contacting with a fluid flowing through and wherein the shaped body ( 8th ) a first end face ( 12 ) and a second end face ( 13 ), comprising the steps of: (a) inserting the shaped body ( 8th ) in a closable container, wherein after insertion of the shaped body ( 8th ) and closing the container within the container, a first chamber ( 2 ) with an adjustable first pressure and a second chamber ( 4 ) are formed with a second pressure independently adjustable from the first pressure, and wherein the shaped body ( 8th ) is inserted so that a fluid from the second chamber ( 4 ) through the shaped body ( 8th ) through to the first chamber ( 2 ) can flow; (b) contacting the second end face ( 13 ) of the shaped body, which in the second chamber ( 4 ) of the container, with a fluid intended for coating ( 10 ); (c) adjusting the second pressure in the second chamber ( 4 ) of the container, so that the second pressure is greater than the first pressure in the first chamber ( 2 ) of the container and wherein the pressure difference is sufficient to make the fluid ( 10 ) through the shaped body ( 8th ) to flow. Process according to claim 1, wherein the fluid intended for coating ( 10 ) the shaped body ( 8th ) flows through to a first predetermined value, after which the second end face ( 13 ) of the molding from that in the second chamber ( 4 ) present for coating fluid ( 10 ) and then continue the second pressure in the second chamber ( 4 ) of the container at a value above the first pressure in the first chamber ( 2 ) of the container is held until in the molded body ( 8th ) provided for coating fluid ( 10 ) the shaped body ( 8th ) has flowed through to a second predetermined value. Process according to claim 1 or 2, wherein the fluid to be coated ( 10 ) in the second chamber ( 4 ) of the container in another container ( 9 ) and wherein the distance of the further container ( 9 ) to the shaped body ( 8th ) is variable to a control command. Method according to one of claims 1 to 3, wherein it is further measured how far the fluid intended for coating ( 10 ) the shaped body ( 8th ) and the measurement is carried out by means of a runtime camera, by means of an X-ray camera, by determining the acoustic resonance of the gas column above the fluid, by means of electrical conductivity measurements and / or by means of electrical resistance measurements. Method according to one of claims 1 to 4, wherein the first pressure in the first chamber ( 2 ) and / or the second pressure in the second chamber ( 4 ) oscillate by a predetermined amount. Method according to one of claims 1 to 5, wherein the fluid front ( 14 ) of the fluid intended for coating ( 10 ) during the flow through the molded body ( 8th ) is acted upon with sound waves. Method according to one of claims 1 to 6, wherein at a predetermined time the second pressure in the second chamber ( 4 ) of the container is set so that the second pressure is less than the first pressure in the first chamber of the container and wherein the pressure difference is ≥ 0.01% to ≤ 10%. Method according to one of claims 1 to 7, wherein at a predetermined time the second pressure in the second chamber ( 4 ) of the container is set so that the second pressure is less than the first pressure in the first chamber ( 2 ) of the container and wherein the pressure difference is sufficient to make the fluid ( 10 ) contrary to the previous flow direction through the molded body ( 8th ) to flow. Device for coating the inner surface of a molded article ( 8th ) comprising a gas impermeable first wall ( 1 ) formed first chamber ( 2 ) and through a gas impermeable second wall ( 3 ) formed second chamber ( 4 ); wherein between the first and the second chamber ( 2 . 4 ) a separation ( 5 ) is arranged; the separation ( 5 ) a continuous recess ( 6 ) for receiving a shaped body ( 8th ) and the separation ( 5 ) is designed otherwise gas impermeable; and wherein the device is further configured to engage in the recess (Fig. 6 ) inserted molding ( 8th ) during coating in the first chamber ( 2 ) a first pressure and independently in the second chamber ( 4 ) to set a second pressure. Apparatus according to claim 9, wherein the second chamber ( 4 ) another container ( 9 ) for receiving a fluid intended for coating ( 10 ) and wherein the distance of the further container ( 9 ) to the shaped body ( 8th ) is variable to a control command.