DE202021103624U1 - WC applicator - Google Patents

Abstract

Applicator (1) for coating a substrate (2) with a coating medium (3), wherein the applicator (1) has at least one supply line (4) for the coating medium (3), a closing plate (9) with at least one opening (5) for Application of the coating medium (3) to the substrate (2) and a cavity (6) in which the coating medium (3) can be distributed before application to the substrate (2), characterized in that in the cavity (6 ) a baffle plate (7) blocks the flow of the coating medium (3) from the supply line (4) to the at least one opening (5) in the depressurized state and when pressure is exerted by the coating medium (3) on the baffle plate (7) the flow of the coating medium ( 3) from the supply line (4) to at least one opening (5).

Description

The present invention is directed to an applicator for applying a coating medium to a substrate. The substrates themselves are used, for example, in catalytic exhaust aftertreatment, particularly in the automotive sector.

Substrates or substrate monoliths are used as catalyst supports in the chemical industry. They also play an important role in the treatment of car exhaust gases. A large number of catalytic emission control technologies have been developed to remove emissions from motor vehicle exhaust gases that are harmful to the environment and human health -Monolithen (wall-flow) is passed with a catalytically active coating applied thereto. The catalytic converter promotes the chemical reaction of various exhaust gas components to form harmless products such as carbon dioxide and water.

The flow-through or wall-flow monoliths just described are accordingly also referred to as catalyst carriers, carriers or also as substrate monoliths, since they carry the catalytically active coating on their surface or in the pores of the wall forming this surface. The catalytically active coating is often applied to the catalyst support in a so-called coating process in the form of a suspension (washcoat). Many such processes have been published in the past by automotive catalytic converter manufacturers ( WO9947260A1 , EP2521618B1 , EP1136462B1 , EP1900442A1 ).

An important aspect of the production of these heterogeneous catalysts is the precise coating of substrates with a washcoat, especially with regard to e.g of layered or zoned coating designs.

In the EP2533901 B1 a coating technique for substrate monoliths is presented, which makes it possible to achieve a particularly precise, zoned coating. A special coating system is used to pump an excess amount of coating suspension into an upright substrate monolith from below. The excess coating suspension in the channels is then sucked off downwards. It is particularly important that a precisely specified amount of coating medium remains on the substrate monolith. Since the coating suspensions often contain expensive precious metals such as platinum, palladium and/or rhodium, too much suspension would mean wasting expensive precious metal. Too little, on the other hand, can result in the catalyst no longer having the necessary catalytic activity.

the EP2415522B1 also shows a coating process in which a coating medium is applied to a substrate from above. The coating medium is fed into a cavity via a supply line via a plunger and then applied to the substrate via openings in a base plate - similar to a shower head. The attempt is made here to achieve the even distribution of the coating medium via the openings and any diffusers that may be present.

Other types of applicators for appropriate coating media are, for example, in JP5925101B2 , the JP201539672A2 and the EP3738681A1 as well as the EP2181821 B1 presented. In the WO2020109771A1 Applicators for a coating medium are presented, which are equipped with baffle plates for the coating medium to be metered in for better distribution of the same in the cavity of the applicator.

Despite these methods known in the prior art, it is still a challenge to coat substrate monoliths sufficiently uniformly. In particular, the dripping of the coating medium after it has been applied to the substrate poses a challenge for the production of substrates. Different coating quantities should be avoided if possible, e.g. due to the high price of precious metals. Uniform coatings are also preferable from a catalytic point of view.

These and other tasks that are obvious to a person skilled in the art are solved by an applicator according to the present claim 1 . Preferred developments of the applicator according to the invention are addressed in the subclaims dependent on claim 1.

By specifying an applicator (1) for coating a substrate (2) with a coating medium (3), the applicator (1) having at least one supply line for the coating medium (4), a closing plate (9) with at least one opening ( 5) for the application of Coating medium on the substrate (2) and a cavity (6) in which the coating medium can be distributed before application to the substrate (2), and in the cavity (6) a baffle plate (7) the flow of the coating medium ( 3) blocked from the supply line (4) to the at least one opening (5) in the pressureless state and when pressure is exerted by the coating medium (3) on the baffle plate (7), the flow of the coating medium (3) from the supply line (4) to the at least one Opening (5) allowed, you get to the solution of the tasks. The applicator described here allows a coating medium to be dosed precisely onto a substrate, such as a substrate monolith for automotive exhaust aftertreatment.

It has proven advantageous if the applicator (1) is designed in such a way that it has approximately the diameter and/or the shape of the end face of the substrate (2) to be coated. Large diameter substrates require larger applicators than smaller ones. Typically the applicator will have a diameter in the range 50-400mm, more preferably 75-350mm. The other components can be selected depending on the size of the applicator. The specialist can carry out the dimensions according to his level of knowledge. The baffle plate (7) is preferably 2-10 mm thick, preferably 4-5 mm. The closing plate (9) then preferably has a thickness of 2-10 mm, more preferably 4-5 mm.

The mechanism of the baffle plate (7) inside the applicator is as follows. A pump, for example, is analogous to the EP2415522B1 the coating medium is metered into the applicator (1) according to the invention. The pressure built up by the coating medium is used to move the impact plate (7) of the applicator in such a way that the path to the closing plate (9) opens up. The coating suspension can thus be pressed into a cavity (6) of the applicator around the baffle plate (7) or, for example, through it (see below). Further pressure from the pump then pushes the coating medium through the opening(s) (5) of the end plate (9). The coating medium flows onto the substrate (2) located under the applicator (1). If the coating process is completed, the pressure of the pump on the coating medium is reduced and the baffle plate (7) closes off the cavity (6) of the applicator from the supply line (4) again. No coating medium can get into the cavity (6) ( 3 and 4 ).

The baffle plate (7) inside the applicator (1), which closes when there is no pressure, prevents the valuable coating medium (3) from dripping onto the end face of the substrate (2). After closing, no further coating medium reaches the openings (5) in the end plate (9). This means that no coating medium can drip out of the applicator after application. This consequently increases the precision of the dosing and allows the production of more uniform catalyst carriers or substrates provided with e.g. catalytic coating during a campaign. The result is less waste.

The baffle plate (7) can be moved by any means available to a person skilled in the art. For example, this can be done by means of a mechanical drive that is controlled by a corresponding pressure sensor or by time. However, it is advantageous if the baffle plate (7) is resiliently mounted in the cavity (6) of the applicator in a robust manner. The spring (10) holds the baffle plate (7) in the depressurized state in such a way that the cavity (6) is closed with respect to the supply line (4). When pressure is applied, it gives way and the baffle plate (7) opens the way from the supply line (4) to the cavity (6). Coating medium (3) can then penetrate into the cavity (6).

The baffle plate (7) can be a simple plate. In the open state, the coating medium can flow over the baffle plate and penetrate into the cavity (6) on the side. Also conceivable and preferred is the embodiment in which the impact plate (7) has at least one opening (8) in its periphery, e.g. in the form of holes. The coating medium can then flow at least through these holes, which then act as a kind of additional diffuser and cause the cavity (6) to be evenly filled with coating medium. The holes must be positioned in such a way that they cannot establish a connection from the supply line (4) to the cavity (6) when they are closed and depressurized. In this context, it is more preferred if the baffle plate (7) has at least one opening (8) through which the coating medium (3) can flow to the opening (5) when pressure is applied. Very preferably, the baffle plate (7) has 2 to 6 circles of holes, each with 12 to 40 openings, depending on the diameter of the applicator, the circles of holes preferably being divided in such a way that the openings are as evenly spaced from one another as possible. The preferred distance between the openings (8) is in a range of 5-20 mm, more preferably in the range of 8-14 mm. The openings (8) mentioned here have different diameters depending on the size of the applicator. It is advantageous if the diameter is in the range of 3-10 mm, more preferably 6-8 mm.

Arriving in the cavity (6), the coating medium (3) is pushed through the opening(s) (5) of the end plate (9) under further pressure. There are preferably several openings (5), one opening in the center and 2-6 circles of holes each with 6 to 40 openings in the periphery. The openings (5) are spaced as evenly as possible from one another. The distance between the openings (5) is preferably in the range of 5-20 mm and very preferably 8-14 mm (again depending on the diameter of the applicator). The opening(s) (5) in the closing plate (9) are preferably designed in the shape of a socket. They protrude outwards beyond the edge of the end plate. They preferably have a length of 5 mm-15 mm, more preferably a length of 6-8 mm. The height of the elevation above the edge of the end plate (9) is around 0.5 - 2.9 mm, more preferably 1.5 - 2.5 mm.

As mentioned, there are preferably several openings (5) in the end plate (9). The preferably socket-shaped openings (5) in the closing plate (9) can be formed according to patterns familiar to the person skilled in the art. They can take any shape (eg, slits, circles, spirals, etc.). In the simplest case, they are round openings. Due to the further prevention of droplet formation and tearing off, the sockets of the openings (5) are preferably designed in a special way. The nozzles have a concave or countersunk opening towards the outflow ( 5 ). The minimum opening of the openings (5) is preferably 1-4 mm, more preferably 2-3 mm. The openings (5) are preferably all the same size.

The dimensions and design of the baffle plate (7) with its openings (8), the cavity (6) and the closing plate (9) with its openings (5) are matched to one another, so that the coating medium (2) is distributed homogeneously the substrate (2) to be coated results.

The entire applicator is preferably made of plastic, but the spring and its plunger are then preferably made of metal. However, it can also be made entirely of metal. The materials are chosen so that they are compatible with the catalytically active coating for car exhaust aftertreatment. The material PE-HD 1000 is preferably used as the plastic, the spring is preferably made of the material EN 10270-3-1.4310, metal parts are preferably made of a stainless steel equivalent or similar to material number 1.4571 (X6CrNiMoTi17-12-2).

The applicator according to the invention can be used in applications contemplated by those skilled in the art. It is advantageous to use the applicator to produce a substrate monolith with a coating that is catalytically active for car exhaust gas aftertreatment. Appropriate procedures in this regard can be found in the literature cited at the outset. The coating medium used here is usually a suspension (slurry, washcoat), which may have acidic or basic properties, but is at least very abrasive (see below). This must be taken into account accordingly in the advantageous embodiment of the applicator according to the invention. The coating media to be used are well known to those skilled in the art.

In this connection, the substrate is preferably of the wall-flow type (wall-flow filter) or of the flow-through type. Flow-through monoliths are catalyst carriers customary in the prior art, which are made of metal (corrugated carrier, e.g WO17153239A1 , WO16057285A1 , WO15121910A1 and literature cited therein) or ceramic materials. Refractory ceramics such as corderite, silicon carbide or aluminum titanate etc. are preferably used. The number of channels per area is characterized by the cell density, which is usually between 200 and 900 cells per square inch (cpsi). The wall thickness of the canal walls is between 0.5 - 0.05 mm for ceramics.

All ceramic materials customary in the prior art can be used as wall-flow monoliths or wall-flow filters. Porous wall-flow filter substrates made of corderite, silicon carbide or aluminum titanate are preferably used. These wall-flow filter substrates have inflow and outflow ducts, with the outflow-side ends of the inflow ducts and the inflow-side ends of the outflow ducts being offset with respect to one another and sealed with gas-tight “plugs”. Here, the exhaust gas to be cleaned, which flows through the filter substrate, is forced to pass through the porous wall between the inflow and outflow channels, which results in an excellent particle filter effect. The filtration properties for particles can be designed through the porosity, pore/radius distribution and thickness of the wall. The porosity of the uncoated wall flow filter is usually more than 40%, generally from 40% to 75%, especially from 50% to 70% [measured according to DIN 66133 - latest version on the filing date]. The average pore size (diameter) of the uncoated filters is at least 7 µm, e.g. B. from 7 microns to 34 microns, preferably more than 10 microns, especially more preferably from 10 microns to 25 microns or very preferably from 15 microns to 20 microns [gemes sen according to DIN 66134 latest version on the filing date].

The coating media considered here are preferably structurally viscous (https://de.wikipedia.org/wiki/Structural Viscosit%C3%A4t). They have a viscosity of 1.0087-1000 mPas, preferably 100-780 mPas, at a shear rate of 100 1/s. They have solid bodies and contain the catalytically active components or their precursors and inorganic oxides such as aluminum oxide, titanium dioxide, zirconium oxide, cerium oxide or combinations thereof, it being possible for the oxides to be doped with silicon or lanthanum, for example. Oxides of vanadium, chromium, manganese, iron, cobalt, copper, zinc, nickel or rare earth metals such as lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium can be used as catalytically active components , Ytterbium or combinations thereof are used. Noble metals such as platinum, palladium, gold, rhodium, iridium, osmium, ruthenium and combinations thereof can also be used as catalytically active components. These metals can also be present as alloys with one another or with other metals, or as oxides. The metals can also be present in the liquid coating medium as precursors, such as nitrates, sulfites or organyls of the precious metals mentioned and mixtures thereof; in particular, palladium nitrate, palladium sulfite, platinum nitrate, platinum sulfite or Pt(NH ₃ ) ₄ (NO ₃ ) ₂ can be used. The catalytically active component can then be obtained from the precursor by calcination at about 400° C. to about 700° C.

For example, metal ions from the group of platinum metals, in particular platinum, palladium and rhodium, have proven to be suitable for the oxidation of hydrocarbons, while the SCR reaction, for example, is most effective with zeolites or zeotypes (molecular sieves with other or additional elements as cations in the framework compared to zeolites) exchanged with iron and/or copper ions. The material that causes the catalytic activity (washcoat) can therefore also contain zeolites or zeotypes. The zeolites or zeotypes that can be used are in principle all types or mixtures thereof which are suitable for the person skilled in the art for the corresponding area of application. These include naturally occurring, but preferably synthetically produced zeolites. These can have framework types, for example from the group consisting of beta, ferrierite, Y, USY, ZSM-5, ITQ. Examples of synthetically produced small-pored zeolites and zeotypes that come into question here are those that have the structure types ABW, ACO, AEI, AEN, AFN, AFT, AFX, ANA, APC, APD, ATN, ATT, ATV, AWO, AWW, BIK, BRE, CAS, CDO, CHA, DDR, DFT, EAB, EDI, EPI, ERI, ESV, GIS, GOO, IHW, ITE, ITW, JBW, KFI, LEV, LTA, LTJ, MER, MON, MTF, NSI, OWE, PAU, PHI, RHO, RTE, RTH, SAS, SAT, SAV, SIV, THO, TSC, UEI, UFI, VNI, YUG and ZON. Preference is given to using those of the small-pored type which are derived from a structure type from the group consisting of CHA, LEV, AFT, AEI, AFI, AFX, KFI, ERI, DDR. Those which are derived from the CHA, LEV, AEI, AFX, AFI or KFI framework are particularly preferred here. A zeolite of the AEI or CHA type is very particularly preferred in this context. Mixtures of the species mentioned are also possible. The SAR value of the zeolite or the corresponding value for the zeotype (eg SAPO -> (Al+P)/2Si) should be in the range from 5 to 50, preferably 10 to 45 and very preferably 20 to 40. For a correspondingly good activity, for example in the SCR reaction, it is necessary for the zeolites or zeotypes and in particular those of the small-pore type to be exchanged with metal ions, in particular transition metal ions. Here the person skilled in the art can use the metal ions which can be used with preference for the corresponding reaction, in particular copper ions. The person skilled in the art knows how such an ion exchange can take place (e.g WO2008/106519A1 ). The degree of exchange (number of ions at exchange sites/total number of exchange sites) should be between 0.3 and 0.5. Exchange sites are those where the positive ions compensate for the negative charges of the lattice. Further non-exchanged metal ions, in particular Fe and/or Cu ions, can preferably also be present in the final SCR catalytic converter. The ratio of exchanged to non-exchanged ions is >50:50, preferably 60:40-95:5 and most preferably 70:30-90:10. The ions sitting on exchange sites are visible in the electron paramagnetic resonance analysis and can be determined quantitatively (Quantitative EPR, Gareth R. Eaton, Sandra S. Eaton, David P. Barr, Ralph T. Weber, Springer Science & Business Media, 2010). Any non-ion-exchanged cations are located elsewhere inside or outside the zeolite/zeotype. The latter do not compensate for a negative charge on the zeolite/zeol-type framework. They are invisible in the EPR and can thus be calculated from the difference between the total metal load (eg determined by ICP) and the value determined in the EPR. The addition of the appropriate ions to the coating mixture is controlled in such a way that the total amount of metal ions, in particular Fe and/or Cu ions, in the final total catalyst is 0.5-10% by weight, preferably 1-5% by weight, of the coating amount lies.

In addition to the components just discussed, the coating medium can also contain other components. These components can further support the catalytic function of the catalytically active material, but do not actively engage in the reaction themselves. Materials used here are, for example, so-called binders. The latter ensure, among other things, that the materials and components involved in the reaction can adhere sufficiently firmly to the corresponding substrate. In this context, binders selected from the group consisting of aluminum oxide, titanium dioxide, zirconium dioxide, silicon dioxide or their oxide hydroxides (for example boehmite) or mixtures thereof have proven to be advantageous components. In the present case, aluminum oxides with a high surface area are advantageously used. The binder is used in a certain amount in the coating. Based on the solid material used in the coating suspension, the further component, for example the binder, is used in an amount of at most 25% by weight, preferably at most 20% by weight and very particularly preferably in an amount of 5% by weight. - 15% by weight used.

The substrate monoliths produced in this way, which are catalytically active in the exhaust gas aftertreatment, can in principle be used in all exhaust gas aftertreatments known to the person skilled in the art for the automotive exhaust gas sector. The catalytic coating of the substrate monolith can preferably be selected from the group consisting of three-way catalytic converter, SCR catalytic converter, nitrogen oxide storage catalytic converter, oxidation catalytic converter, soot ignition coating. With regard to the individual catalytic activities in question and their explanation, reference is made to the statements in WO2011151711A1 referred.

reference list

1

applicator

2

substrate to be coated

3

coating medium

4

Lead area inside the applicator (1)

5

Opening in the end plate (9)

6

cavity inside the applicator (1)

7

flapper

8th

Opening in the flapper (7)

9

end plate

10

collar

• 1 : 1 shows the applicator according to the invention in a plan view diagonally from above.
• 2 : 2 shows the applicator according to the invention in a view obliquely from below.
• 3 : 3 shows a cross section through the applicator according to the invention. In particular, the resilient suspension of the baffle plate (7) within the applicator (1) can be seen.
• 4 : 4 shows the installation of the applicator (1) in a corresponding coating system. The coating medium is metered onto the end face of a substrate (2). A kind of collar (10) is laid/put around this end face, which is intended to prevent the coating medium from running down the end face on the sides of the substrate (2).
• 5 You can see the concave or countersunk bulges of the sockets, which represent the opening(s) (5).

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• WO 9947260 A1 [0003]
• EP 2521618 B1 [0003]
• EP 1136462 B1 [0003]
• EP 1900442 A1 [0003]
• EP 2533901 B1 [0005]
• EP 2415522 B1 [0006, 0012]
• JP 5925101 B2 [0007]
• JP 201539672 A2 [0007]
• EP 3738681 A1 [0007]
• EP 2181821 B1 [0007]
• WO 2020109771 A1 [0007]
• WO 17153239 A1 [0021]
• WO 16057285 A1 [0021]
• WO 15121910 A1
• WO 2008/106519 A1 [0024]
• WO 2011151711 A1 [0026]

Claims (7)

Applicator (1) for coating a substrate (2) with a coating medium (3), the applicator (1) having at least one supply line (4) for the coating medium (3), a closing plate (9) with at least one opening (5) for Application of the coating medium (3) to the substrate (2) and a cavity (6) in which the coating medium (3) can be distributed before application to the substrate (2), characterized in that in the cavity (6 ) a baffle plate (7) blocks the flow of the coating medium (3) from the supply line (4) to the at least one opening (5) in the depressurized state and when pressure is exerted by the coating medium (3) on the baffle plate (7) the flow of the coating medium ( 3) from the supply line (4) to at least one opening (5). Applicator (1) after claim 1 , characterized in that the baffle plate (7) is resiliently mounted in the cavity (6). Applicator (1) after claim 1 and/or 2, characterized in that the baffle plate (7) has at least one opening (8) through which the coating medium (3) can flow to the opening (5) when pressure is applied. Applicator (1) after claim 1 until 3 , characterized in that the at least one opening (5) is in the form of a socket and has a total length of 5-15 mm. Applicator (1) after claim 4 , characterized in that the sockets of the opening (5) project outwards by 0.5 - 2.9 mm over the end plate (9). Applicator (1) after claim 4 and/or 5, characterized in that the sockets of the opening (5) have a concave or countersunk opening towards the outflow. Use of an applicator according to any one of Claims 1 - 6 for the production of a substrate monolith with a catalytically active coating for car exhaust gas aftertreatment.

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