JP2018012049A - Resin-coated honeycomb structure, honeycomb structure type catalyst and method for producing them - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin coated honeycomb structure which has an opaque chromatic resin coating thereon and thereby facilitates confirmation of completion of coating of an outer wall portion to an outside surface and infiltration of the outer wall portion to an appropriate depth to the honeycomb structure outer wall portion, can prevent bleeding of a catalyst slurry to the outer wall portion, in particular, at the time of application of a wash coat method, and can secure air permeability of the outer wall portion as a carrier of a gasoline particulate filter (GPF), and to provide a method for producing a honeycomb structure type catalyst and a honeycomb structure type catalyst using the same.SOLUTION: A resin-coated honeycomb structure has a partition wall which is formed of a porous inorganic oxide and partitions and forms a plurality of cells extending to an outlet end face becoming an outlet side of a fluid from an inlet end face becoming an inlet side of the fluid, a honeycomb base material having an outer wall portion being a side face, and a colored resin coating formed on the outside surface of the outer wall portion.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a resin-coated honeycomb structure, a honeycomb structure-type catalyst, and a method for producing them. More specifically, by providing a colored resin coating on the surface, the coating of the outer surface of the outer wall portion is completed and the outer wall portion of the honeycomb structure body is formed. It is easy to confirm the penetration of the catalyst to an appropriate depth, and it is possible to prevent the catalyst slurry from leaching to the outer wall when applying the wash coat method, and the outer wall as a carrier for the gasoline particulate filter (GPF). The present invention relates to a resin-coated honeycomb structure that can ensure the air permeability of the catalyst, and a honeycomb structure-type catalyst using the resin-coated honeycomb structure and a manufacturing method thereof.

  The exhaust gas of automobiles contains various harmful components, and various methods have been proposed and implemented for purification. As harmful components contained in such automobile exhaust gas, nitrogen oxides represented as NOx, unburned hydrocarbons derived from fuel represented as HC, and carbon monoxide represented as CO are known. .

  Automobiles that generate exhaust gas include automobiles using gasoline as fuel and diesel cars equipped with diesel engines using light oil as fuel. Regarding exhaust gas discharged from diesel vehicles, in addition to the above NOx, HC, and CO, PM (Particulate Matter) as a particulate component is also known, and DPF (Diesel) is used as a device for purifying such PM. Particulate Filter) has been widely used.

  DPF is a general term for an exhaust gas purification filter device also called a wall flow honeycomb filter, but its structure is composed of a plurality of cells partitioned by partition walls from the inlet end portion toward the outlet end portion. The honeycomb structure is alternately sealed at the outlet end. The partition which comprises a cell has air permeability, PM is removed by filtering PM out of waste gas using this air permeability. If the PM filtered out from the exhaust gas by the DPF is left as it is, it will continue to accumulate in the DPF and cause clogging. Therefore, the PM is generated by the heat of the exhaust gas or the injection of fuel into the combustion chamber or exhaust gas of the engine. To regenerate the DPF on which PM is deposited. For the purpose of promoting such regeneration, a catalyst component may be coated on the partition walls of the DPF cell, and the DPF coated with the catalyst component may be referred to as a CSF (Catalyzed Soot Filter). The present applicant has also proposed such a system (see, for example, Patent Document 4).

  Conventionally, many automobiles that have been required to purify PM in exhaust gas are diesel cars, but they are generated by using light oil that is hard to burn as compared to gasoline. An automobile that easily burns and generates a small amount of PM has not received much attention as an environmental problem.

  However, with increasing interest in environmental problems, regulations on harmful components in exhaust gas have become more stringent, and there is a movement to regulate the amount of PM emitted from gasoline automobiles. In recent years, in particular, the market is also concerned about fuel consumption, and direct-injection engines that supply gasoline directly into the combustion chamber under precise control are becoming mainstream in gasoline engines. However, in such direct-injection gasoline, the combustion chamber is in a combustion state while a part of the sprayed gasoline is kept in a fine particle state, so that the conventional combustion is caused by incomplete combustion derived from particulate fuel. Compared to a gasoline vehicle that supplies a mixed gas of fuel and air from an intake manifold, more PM is generated, and the necessity of emission regulations has become more realistic.

  As for the PM discharged from such a gasoline vehicle, it is conceivable to use a wall flow honeycomb filter in the same manner as the DPF used in the diesel vehicle. However, the DPF used in the diesel vehicle easily from the characteristics of the gasoline vehicle. It was difficult to divert as it was for the following reasons.

  One of the major differences between gasoline vehicles and diesel vehicles is the exhaust gas flow velocity. A diesel engine injects fuel into compressed air at high pressure, ignites the fuel by the action of the pressure, and extracts kinetic energy by causing it to explode. Although it is an efficient engine due to its high compression, it is necessary to create a high compression state, so the engine speed is lower than that of a gasoline vehicle, and therefore the exhaust gas flow rate is also slow. In this way, in the DPF designed for exhaust gas with a slow flow rate, it is not necessary to obtain air permeability to the outer wall part which is the side surface of the honeycomb structure. In the conventional DPF, the outer wall part is dense in order to improve the strength of the honeycomb structure. Made of high strength ceramic material.

  However, the situation of exhaust gas emitted from gasoline engines is different from that of diesel engines. Since a gasoline engine ignites an air-fuel mixture by a spark plug, the compression ratio is smaller than that of a general diesel engine. As a result, the engine can be operated at a high speed and a high output can be obtained. Further, due to demands from the market regarding fuel efficiency improvement in recent years, high-power engines tend to be downsized for the purpose of reducing vehicle weight. In order to obtain high output with a small engine, it is necessary to operate the engine at a high speed or supply a large amount of air into the cylinder by a supercharger. However, exhaust from an engine operated at a high speed or in a supercharged state is required. The flow rate of the exhaust gas is further increased. If a conventional DPF is used for such exhaust gas having a high flow velocity, the back pressure increases and becomes an obstacle to improving the engine output.

Therefore, in the filter used to remove PM in the exhaust gas discharged from the gasoline engine, the outer wall portion is not breathable without providing a dense outer wall portion that is not breathable and demands strength like DPF. Honeycomb filters with a slag have been studied. Such a PM filter for a gasoline engine is sometimes referred to as a GPF (Gasoline Particulate Filter) (see, for example, Patent Document 3).
With GPF, it is possible to remove PM in the exhaust gas without unnecessarily increasing the back pressure. On the other hand, a new problem has arisen in production as a catalyst.

Also, unlike DPF, GPF uses different temperatures. In general, there is a large temperature difference between diesel engine exhaust gas and gasoline engine exhaust gas. Compared to a diesel engine that is used at a relatively low speed, a gasoline engine is used at a high speed, so the exhaust gas becomes hot. For this reason, when a honeycomb filter having a dense outer wall portion that is not air permeable and has a strong strength as in a conventional DPF is used for gasoline engine exhaust gas, the difference in coefficient of thermal expansion between the material of the partition wall and the outer wall portion of the cell There is a concern about the occurrence of cracks. The occurrence of cracks due to such thermal history is sometimes referred to as thermal shock.
There is a concern that thermal shock also occurs when GPF without a dense outer wall is catalyzed. In general, various inorganic fine particles are used in the catalyst composition, and when such inorganic fine particles enter the outer wall portion, the inorganic fine particles that have come into contact with the high-temperature exhaust gas are thermally expanded. The thermal shock accompanying such catalysis may occur not only when the gasoline engine is used but also under heating conditions when the GPF is catalyzed.

  Generally, a three-way catalyst (TWC) containing noble metals such as platinum, palladium, and rhodium is used to purify exhaust gas from gasoline engines. A component that uses noble metals to purify NOx, HC, and CO simultaneously. A honeycomb structure catalyzed with is used. The conventional TWC is not a honeycomb structure in which both ends of the cell are plugged together like the DPF, but a catalyst component is coated on the partition walls of the honeycomb cell in which both ends of the cell, called a flow-through honeycomb, are released. Have been used. Such a flow-through honeycomb has little increase in back pressure and is suitable for use in exhaust gas at a high flow rate like a gasoline engine.

  In the case of catalyzing not only the flow-through honeycomb but also the DPF with a catalyst composition such as TWC, a washcoat method is generally applied (for example, see Patent Document 2). As for the washcoat method, various methods have been proposed and implemented, but the basic principle is “the step of supplying the slurry catalyst component into the honeycomb cell”, “the catalyst in the supplied cell” It consists of a process of discharging the slurry by air pressure. In the “step of discharging the supplied catalyst slurry by air pressure”, if the flow-through honeycomb is used, it is possible to remove excess slurry without any particular trouble. In addition, since the conventional DPF also has a dense outer wall portion, the surplus of the slurry supplied to the inside of the cell can be removed without any trouble in this case.

However, since GPF has a problem of suppressing an increase in back pressure, its outer wall portion is made of a porous material having air permeability like the partition walls of the cell, and the exhaust gas needs to be able to be vented from the outer wall portion. However, in the honeycomb used for GPF, since the end of the cell is plugged, the plugged portion becomes an obstacle in the “step of discharging the catalyst slurry in the supplied cell by air pressure” in the wash coat method. There was a problem that the slurry discharged by air pressure leached from the outer wall.
If the slurry leaches out from the outer wall in this manner, not only the apparatus used for the wash coat method becomes dirty but also expensive noble metals are wasted. Further, since an expensive precious metal is used as a component in an automobile catalyst, the amount of the component is required to be strictly controlled for the purpose of cost control, and leaching of slurry from the outer wall portion is required. It is regarded as a manufacturing defect because of the need to meet the requirements. In addition, the performance of an automobile catalyst can only be industrially implemented by controlling the amount of the catalyst appropriately. However, the slurry is leached to the outer wall, so that the catalyst supported by each honeycomb in mass production. It became extremely difficult to manage the amount and to realize a stable purification performance.
Thus, a means for preventing the slurry from leaching from the outer wall portion of the GPF has been desired. However, as such means, it is possible to say that the slurry should not be leached from the outer wall portion when applying the wash coat method, and that it should not adversely affect the product after applying the catalyst. It is desirable that it is a means which can achieve simultaneously. In addition, it is also desired to be a means that can be stably and inexpensively applied and can be mass-produced.

  On the other hand, in order to prevent the catalyst component-containing liquid from oozing out to the outer wall portion of the honeycomb filter, it is conceivable to form a coating on the outer peripheral portion. For example, Patent Document 1 proposes marking with an inorganic filler for catalyst identification. Further, in Patent Document 5, when the coating layer is infiltrated into the outer periphery of the outer peripheral wall of the honeycomb structure at a thickness of 1 to 90% of the thickness of the outer peripheral wall, the catalyst slurry exudes to the surface of the outer peripheral wall. It is disclosed that not only the strength of the outer peripheral wall but also the isostatic strength of the entire structure can be improved.

Republished 2003-0778064 Special table 2003-506221 gazette JP-T-2015-528868 Republished 2013-172128 Japanese Patent Laid-Open No. 2006-055282

However, the honeycomb structure including the inorganic filler in Patent Document 1 cannot be applied to GPF because the inorganic filler blocks the pores of the outer skin and increases the pressure loss.
On the other hand, as in Patent Document 5, if the coat layer penetrates into the outer periphery of the outer peripheral wall of the honeycomb structure at a thickness of 1 to 90% of the thickness of the outer peripheral wall, the slurry from the outer wall at the time of applying the wash coat method. Can be prevented to a certain extent, and the coating layer is burned out during firing, so that the increase in pressure loss can be suppressed to some extent, but it is not easy to confirm how much resin is coated on the honeycomb substrate during catalyst preparation. It was. That is, in the case of Patent Document 5, since the resin coating tends to be non-uniform when the thickness of the coat layer is small, it is ensured that the slurry leaches out from the outer wall portion, and the coat layer is burned out during firing to suppress an increase in pressure loss. It couldn't be realized.
Further, it has not been possible to solve the concern about the occurrence of thermal shock that occurs on the outer wall by catalyzing with a composition containing inorganic fine particles.

  In view of the above-described problems of the prior art, the object of the present invention is to provide a colored resin coating on the surface to complete the coating on the outer surface of the outer wall and to an appropriate depth to the outer wall of the honeycomb structure. A resin that can easily check the intrusion and can prevent the catalyst slurry from leaching to the outer wall when applying the wash coat method, and can ensure the air permeability of the outer wall as a carrier for a gasoline particulate filter (GPF). It is an object of the present invention to provide a coated honeycomb structure, a honeycomb structure type catalyst, and a method for producing them.

  As a result of intensive studies to solve the above problems, the present inventors have found that a honeycomb structure composed of a porous inorganic oxide and having partition walls and an outer wall portion is provided with a colored resin coating. It is easy to confirm the completion of the resin coating on the outer surface of the section and the penetration of the resin to an appropriate depth into the outer wall of the honeycomb structure. It was found that leaching to the outer wall portion can be prevented and that the air permeability of the outer wall portion can be secured when used as a GPF, and the present invention has been completed.

  That is, according to the first aspect of the present invention, the partition wall is formed of a porous inorganic oxide and defines a plurality of cells extending from an inlet end surface serving as a fluid inlet side to an outlet end surface serving as a fluid outlet side. There is provided a resin-coated honeycomb structure comprising a honeycomb substrate having an outer wall portion which is a side surface, and a colored resin coating formed on an outer surface of the outer wall portion.

  According to the second invention of the present invention, in the first invention, at least a part of the hole before the resin coating is formed on the outer surface of the outer wall portion on which the resin coating is formed, There is provided a resin-coated honeycomb structure characterized in that a sealing hole or a hole opening size is narrowed by resin coating.

  Further, according to the third invention of the present invention, in the first or second invention, the honeycomb substrate includes openings on the inlet end face side of predetermined cells and openings on the outlet end face side of remaining cells. There is provided a resin-coated honeycomb structure having a filter structure having a plugged portion for plugging an end portion.

  According to a fourth invention of the present invention, in any one of the first to third inventions, the outlet end surface is composed of a porous inorganic oxide, and is an outlet end surface that is a fluid outlet side from an inlet end surface that is a fluid inlet side. A resin substrate containing a colorant is applied to a honeycomb substrate having partition walls that form a plurality of cells extending to the outer wall and side walls that are side surfaces, and then dried and cured to form a resin coating. A method for manufacturing a resin-coated honeycomb structure is provided.

  According to a fifth aspect of the present invention, in the fourth aspect, the resin solution includes at least one resin selected from polyvinyl alcohol (PVA) and acrylic resin. A mass% manufacturing method of the structure is provided.

  According to a sixth invention of the present invention, in the fifth invention, the resin is polyvinyl alcohol (PVA), and used as an aqueous solution having an average degree of polymerization of 1500 to 3000 and a concentration of 3 to 10% by mass. A method for producing a resin-coated honeycomb structure is provided.

  According to a seventh aspect of the present invention, there is provided the method for producing a resin-coated honeycomb structure according to any one of the fourth to sixth aspects, wherein the resin coating disappears by heat of 400 ° C. or higher. Is provided.

  Further, according to the eighth invention of the present invention, the cell-partition of the honeycomb structure is formed by the washcoat method including the pressurizing step using the resin-coated honeycomb structure of any one of the first to third inventions. There is provided a method for producing a honeycomb structure type catalyst, which is characterized by coating a catalyst composition slurry.

  According to a ninth aspect of the present invention, in the eighth aspect, the method further comprises a step of firing the resin-coated honeycomb structure after being coated with the catalyst composition slurry, and at least the color of the resin coating is increased by the firing. There is provided a method for producing a honeycomb structured catalyst characterized in that a part thereof disappears.

  Furthermore, according to a tenth aspect of the present invention, in the eighth or ninth aspect, the catalyst composition slurry contains at least one noble metal element selected from Pt, Pd and Rh. A method for producing a structured catalyst is provided.

  On the other hand, according to the eleventh invention of the present invention, it is obtained by the method of any one of the eighth to tenth inventions, and the outer surface of the outer wall portion is substantially free of the catalyst composition and has air permeability. A featured honeycomb structured catalyst is provided.

  Furthermore, according to the twelfth aspect of the present invention, there is provided a honeycomb structure type catalyst according to the eleventh aspect, wherein the honeycomb structure type catalyst is used as a gasoline particulate filter (GPF).

In the resin-coated honeycomb structure of the present invention, by providing a colored resin coating on the surface, it becomes easy to identify whether or not the coating on the outer surface of the outer wall portion is completed, and the resin is applied to the outer wall portion of the honeycomb substrate. Therefore, it is easy to confirm whether or not the material has sufficiently penetrated to the appropriate depth, so that the resin-coated honeycomb structure as the catalyst carrier can be stably and inexpensively manufactured, and mass production is possible.
In addition, the resin-coated honeycomb structure of the present invention can prevent the catalyst slurry from leaching to the outer wall when applying the washcoat method when manufacturing a honeycomb structure-type catalyst using the resin-coated honeycomb structure, and can be used as a GPF. Has the effect of ensuring the air permeability of the outer wall. Moreover, since it becomes difficult for the catalyst composition to enter the outer wall portion, occurrence of thermal shock in the outer wall portion is also suppressed.
Therefore, the honeycomb structure type catalyst according to the present invention can be used particularly preferably as a honeycomb structure for GPF.

FIG. 4 is a photograph showing a surface state after applying a resin composition containing a colorant in a process for producing a resin-coated honeycomb structure of the present invention, and a photograph showing a surface state after a subsequent drying step. When the left (A row) is sufficiently covered with resin, the right (B row) is a photograph when the resin coating is insufficient. FIG. 2 is a photograph showing a surface state after coating without coloring the resin composition in a process of manufacturing a comparative resin-coated honeycomb structure, and a photograph showing a surface state after a subsequent drying step. When the left (A row) is sufficiently covered with resin, the right (B row) is a photograph when the resin coating is insufficient. It is explanatory drawing which shows typically the coating device of a resin composition, and its use in the process of manufacturing a resin-coated honeycomb structure. It is explanatory drawing which shows typically the coating device different from FIG. 3, and its use.

The resin-coated honeycomb structure of the present invention includes a honeycomb structure made of a porous inorganic oxide and having partition walls and outer wall portions, and a colored resin coating formed on at least a part of the outer surface of the outer wall portions. ing. The present invention relates to a method for producing this resin-coated honeycomb structure, a method for producing a honeycomb structure-type catalyst comprising a step of coating the cell partition walls of the resin-coated honeycomb structure with a catalyst composition slurry by a wash coat method, and a honeycomb obtained. The present invention relates to a structure type catalyst.
Hereinafter, the present invention will be described in detail for each item.

1. Honeycomb base material The honeycomb base material ("honeycomb structure" as a catalyst carrier) used in the present invention is composed of a porous inorganic oxide, and an outlet end surface that is the fluid inlet side is an outlet end that is a fluid outlet side. It has the partition which partitions and forms the some cell extended to an end surface, and the outer wall part which is a side surface. The partition walls form a plurality of through-hole cells extending from one end face toward the other end face, and these gather together to form a honeycomb shape.
Honeycomb structures are roughly classified into a flow-through type (flow-through honeycomb) and a wall-flow type (wall-flow honeycomb) because of the characteristics of the structure. The flow-through type is widely used for oxidation catalysts, reduction catalysts, and three-way catalysts because a large number of through-hole ends that open from one open end surface to the other open end surface are not sealed. On the other hand, in the wall flow type, one end of the through-hole is alternately sealed, and solid components such as soot and SOF (Soluble Organic Fraction) in exhaust gas can be filtered out. Therefore, it is used as a DPF. The present invention can be used for either of them, but it can be suitably used particularly for a wall flow honeycomb because the catalyst slurry can be prevented from leaching to the outer wall during GPF production.

  The average pore diameter of the honeycomb base material (partition walls and outer peripheral wall) is preferably 10 to 30 μm, and particularly preferably 15 to 25 μm. When the average pore diameter of the honeycomb base material is less than 10 μm, the pressure loss of the honeycomb structure becomes too high, and when used as a GPF, the engine output may be reduced. Further, when the average pore diameter of the honeycomb substrate exceeds 30 μm, sufficient strength may not be obtained. Here, the “average pore diameter” is a value measured by a mercury porosimeter.

  The thickness of the partition walls of the honeycomb base material is preferably 150 to 350 μm, particularly preferably 200 to 310 μm. If the partition wall thickness is less than 150 μm, sufficient strength may not be obtained. When the partition wall thickness exceeds 350 μm, the pressure loss of the honeycomb structure becomes too high, and when used as a GPF, the engine output may be reduced.

  The thickness of the outer peripheral wall of the honeycomb base material is preferably 300 to 1000 μm, particularly preferably 500 to 800 μm. If the thickness of the outer peripheral wall is less than 300 μm, sufficient strength may not be obtained. When the thickness of the outer peripheral wall exceeds 1000 μm, the pressure loss of the honeycomb structure becomes too high, and when used as a GPF, the engine output may be reduced.

The cell formed by the partition walls is usually about 0.8 to 2.5 mm in diameter or one side, and its density is expressed by the number of holes per unit cross-sectional area, which is also called cell density. The cell density of the honeycomb structure is not particularly limited, but is preferably 100 to 1200 cells / inch ² (15.5 to 186 cells / cm ² ), and 150 to 600 cells / inch ² (23 to 93 cells / cm ² ). Is more preferable, and 200 to 400 cells / inch ² (31 to 62 cells / cm ² ) is particularly preferable. When the cell density exceeds 1200 cells / inch ² (186 cells / cm ² ), clogging is likely to occur due to catalyst components and solids in the exhaust gas, and pressure loss becomes too high. In addition, engine output may be reduced.
If it is less than 100 cells / inch ² (15.5 cells / cm ² ), the geometric surface area becomes small, so that the effective usage rate of the catalyst is lowered and the usefulness as an exhaust gas purification catalyst may be lost. Further, when used as a GPF, the effective area as a filter is insufficient, the pressure loss after PM deposition becomes high, and the output of the engine may be reduced.
Moreover, 1-18 mil (0.025-0.47 mm) is preferable and, as for the thickness of the partition which is a cell wall, 6-12 mil (0.16-0.32 mm) is more preferable. If the partition wall is too thin, it becomes structurally brittle, and if it is too thick, the geometric surface area of the cell becomes small, which may reduce the effective usage rate of the catalyst. Further, if the partition wall is too thick, the pressure loss may increase.

The honeycomb structure used in the present invention needs to be formed of a porous inorganic oxide. This is because when the GPF is manufactured, the catalyst slurry can be prevented from leaching to the outer wall portion by coating, and when used as a filter, the outer wall portion needs to have air permeability.
In particular, in the GPF for gasoline vehicles, since the exhaust gas needs to be released to the outside from the partition walls constituting the honeycomb, the partition walls are also formed of a porous body, and a large number of pores exist in the cell wall and the outer wall portion. It is preferable.
Moreover, it is preferable that a partition and an outer wall part are formed with the same material, and also it is preferable that it is integral molding by the same material. This is because efficient production is possible and problems due to differences in materials can be avoided.

  As the material for the honeycomb substrate, ceramic materials such as silicon carbide, silicon-silicon carbide based composite material, cordierite, mullite, alumina, spinel, silicon carbide-cordierite based composite material, lithium aluminum silicate, and aluminum titanate are preferable. Among these, cordierite is particularly preferable. This is because when the honeycomb base material is cordierite, a honeycomb structure having a small thermal expansion coefficient and excellent thermal shock resistance can be obtained.

The shape of the honeycomb structure is not particularly limited, and includes a generally known columnar shape, an elliptical columnar shape similar to a columnar shape, and a polygonal column. A cylindrical shape or an elliptical column shape is preferable.
That is, since the honeycomb structure is preferably manufactured by applying the resin composition to the outer skin portion using a plurality of rollers, it is easy to form a uniform coating when the cross-sectional shape is circular, Film formation is possible. Moreover, the surface of the outer skin portion of the honeycomb structure can be roughened beforehand, or the surface can be chemically treated to make it easy to form a coating.
Further, the shape of the cell in the cross section perpendicular to the longitudinal direction of the honeycomb substrate (hereinafter referred to as “cell shape”) is not particularly limited, but is a polygon such as a quadrangle, hexagon, octagon, or a combination thereof. For example, a combination of a square and an octagon is preferable.

2. Resin-coated honeycomb structure The resin-coated honeycomb structure of the present invention includes a colored resin coating formed on at least a part of the outer surface of the outer wall portion of the honeycomb structure. The resin coating is preferably formed by applying and drying a colored resin solution.

The resin coating suppresses the entry of the catalyst slurry into the outer wall during the manufacture of the honeycomb structure-type catalyst, so that the resin solution (hereinafter sometimes referred to as “sealer”) is used to cover the outer wall of the honeycomb structure. Uniform impregnation coating is required.
However, if the resin used for the sealer is colorless, there are cases where it is difficult to identify the portion not covered with the sealer. Furthermore, if it is dried after applying the sealer, it may become impossible to distinguish between a painted place and an unpainted place. In particular, a honeycomb made of a fired ceramic body has a smooth and rough surface and water absorption, so there is no reflection after the coating is formed. Discrimination tends to be more difficult.
Also, if the sealer penetrates too deeply into the inside of the outer wall, the catalyst composition will not adhere to the cell wall surface during wash coating on the cell wall of that part, or it will not be able to penetrate inside the cell wall, and the honeycomb This may lead to a reduction in the catalytic area. If it is a transparent sealer, it is difficult to identify how much the sealer has penetrated, and there is a risk that appropriate production management (implementation) may be difficult.
Therefore, if the honeycomb base material is coated with a colored resin by using a colored resin composition, not only at the time of coating formation but also after drying, or even a honeycomb made of a ceramic fired body, It is possible to distinguish between a painted place and a non-painted place. At this point, it is possible to determine whether the coating is good or bad, and the manufacturing yield can be improved.

In addition, on the outer surface of the outer wall portion on which the resin coating is formed, at least a part of the hole before the resin coating is formed is sealed or the opening size of the hole is narrowed by the resin coating. preferable. Sealing means that the opening size is zero, and the restriction hole means that the opening size is smaller than that of the previous hole, and the restriction hole may be 1/3 or less of the porosity formed by the previous hole. It is more preferably 1/10 or less.
In addition, the penetration depth of the sealer can be determined as appropriate, but it is preferable that the depth of the sealer has reached approximately one cell in the immediate vicinity of the outer wall, and further improvement in strength is expected when reaching the second cell. It should be noted that the GPF having a large size can have three or more cells, but if the size is small, the catalyst loading decreases as the penetration depth increases.

3. Production of Resin-Coated Honeycomb Structure The resin-coated honeycomb structure of the present invention can be applied without limitation as long as it can form a colored resin coating on at least a part of the outer surface of the outer wall portion of the honeycomb structure. For example, a method of forming a resin coating using a roller can be employed, and an example is a method using two or more rollers.

As the roller, for example, either a roller having a driving function and a coating function (also referred to as “driving and coating roller”) or a roller having a coating function (also referred to as “coating roller”) is used, and the coating roller Can be used in combination with a roller having a driving function (also referred to as “driving roller”). By using such a roller, the outer wall portion of the honeycomb structure can be coated with a resin, and catalyst slurry can be prevented from leaching to the outer wall portion during the manufacture of a catalyst to which the washcoat method is applied.
In addition, such coating does not necessarily need to fill all the pores of the porous body in the outer wall portion with the coating. As described above, for example, when the wash coat method is applied, the catalyst slurry is formed on the outer wall. It is only necessary that the hole is shrunk by the coating to the extent that it can be prevented from leaching into the part.
A roller is not restrict | limited by a material, The ceramic similar to a honeycomb can be used, and also wood and a metal may be used. Sponge-like materials such as urethane foam, polyvinyl alcohol, cellulose-based, rubber-based, silicone-based or non-woven fabric may be attached to these surfaces so that they are easily wetted by the emulsion and do not cause scratches when in contact with the honeycomb structure. it can.

Any driving roller can be used as long as it can be rotated at least partially in contact with the honeycomb structure. The outermost surface is preferably made of a sponge-like material such as urethane foam.
Although the shape of the drive roller has a relationship with the shape of the honeycomb structure, it is usually easy to rotate relatively uniformly when the cross-sectional shape is circular, and an elliptical shape can also be used. Further, the size of the driving roller is appropriately selected in consideration of the restrictions of the apparatus.
Further, when the driving roller has ribs formed in the circumferential direction, the contact area between the driving roller and the honeycomb structure is reduced, and the problem that the coating liquid adheres to the driving roller can be prevented. Therefore, it is preferable.

Any coating roller may be used as long as it can form a coating on at least a part of the outer wall portion of the honeycomb structure by coating a coating solution. The outermost surface is preferably formed of a sponge-like material. Hereinafter, the same applies to the “drive and application roller”.
As a method of supplying the application liquid to the application roller, when the outermost surface of the application roller is formed in a sponge shape, for example, a container filled with the application liquid on at least the outermost sponge-like material portion of the application roller. It is preferable to immerse in. Further, the coating roller itself has a structure having a pipe-shaped core part with a hole in the side surface, and the coating liquid can be supplied to the core part.
The honeycomb structure is preferably rotated in conjunction with a roller having a coating function. The honeycomb structure is preferably applied by being pressed against a roller having a coating function. This is because a preferable coating can be formed by controlling the coating amount, coating pressure and the like in accordance with the situation such as the type of coating solution.

The size of the application roller is usually the same as that of the honeycomb structure, or 50 to 300 mm in length, preferably 80 to 200 mm, and preferably 30 to 500 mm in diameter. When the coating roller is shorter than the honeycomb structure, the length is applied to a part of the honeycomb surface, and when the coating roller is longer than the honeycomb structure, the length can be applied to the entire surface of the honeycomb. Therefore, it is preferable.
In addition, the diameter of the application roller is not limited, but if the diameter of the application roller is different from the diameter of the honeycomb structure, an effect of preventing splashing of the application liquid may be exerted.
Moreover, the application roller can attach the member for removing the excess application liquid of the application part of the said honeycomb structure to the roller terminal part depending on the kind etc. of application liquid. As this member, for example, a metal column or a rotatable member whose surface is covered with rubber having a thickness of several millimeters can be used.

  In the present invention, a coating solution containing a colored resin component is used. The resin component of the coating liquid is preferably an organic material, for example, having a double bond or a reactive functional group, and is heated after coating with an acrylic resin, an acrylic silicon resin, an acrylic styrene resin, a vinyl acetate resin or a polyurethane resin. The thermosetting monomer is preferably used in the form of an emulsion dispersed or dissolved in an aqueous solvent.

  Preferable examples also include polyvinyl alcohol that solidifies by drying, (ultra) low density polyethylene, polyethylene glycol (PEG), agar, gelatin, starch, sucrose, and the like. These are also preferably used in the form of an emulsion in which a low molecular weight polymer is dispersed or dissolved in an aqueous solvent. The organic material is formed using a water-soluble polymer, and the raw material is preferably an aqueous emulsion in which a resin monomer or a low molecular weight resin is dispersed or dissolved in water as a solvent. The organic resin needs 1 to 50% by mass, preferably 3 to 40% by mass of the whole emulsion.

On the other hand, those based on organic resins that are solid at room temperature, such as high molecular weight non-hydrophilic waxes and organic pigments, can be used, but as such, application to the honeycomb may be difficult. If the coating molding component does not easily enter the macro pores from the outer skin of the honeycomb, uneven coating occurs and it is difficult to suppress the bleeding of the slurry, but even with such a component, a medium such as water or an organic solvent In some cases, it can be used by devising such as dispersion or dissolution.
The resin solution is preferably composed of an aqueous solution containing polyvinyl alcohol (PVA) having an average degree of polymerization of 1500 to 3000 and a concentration of 3 to 10% by mass. More preferable is an aqueous solution containing polyvinyl alcohol (PVA) having an average degree of polymerization of 1700 to 2100 and a concentration of 4 to 6% by mass.
On the other hand, Patent Document 5 describes inorganic silicone oil. Many of these are highly viscous or difficult to dissolve in a solvent such as water / alcohol, and are difficult to be impregnated in the honeycomb outer skin portion, so that they often do not reach the inner wall of the cell.

The organic material may contain the organic resin as a main component and an inorganic filler. That is, as for the amount of the organic resin, it is preferable that the total of the adhesion amount to the honeycomb outer surface and the encapsulation amount of the cell outer shell to the macropore is at least 90% by mass of the whole material.
As the inorganic filler, titania, alumina, silica and the like may be contained, but the amount is preferably 10% by mass or less, and more preferably 5% by mass or less. If the amount of the inorganic filler exceeds 10% by mass, the material that has penetrated into the macropores in the cell may remain after the catalyst is loaded, and the pores may be reduced, causing pressure loss and cracking. If the solvent is water, it is safe and inexpensive, but an organic solvent such as alcohol may be used. Considering the subsequent drying step, ethanol having a low boiling point is more preferable.

  The aqueous resin solution further contains a colorant as an essential component. Coloring means a state in which a dye or pigment is dissolved or dispersed in a resin. Since dyes have relatively high solubility, they are often added directly to resins and solvents. However, since the powder pigment is difficult to dissolve in the resin, a dispersing agent such as a vehicle (color developing material), metal soap, or metal stearate is blended so that it can be mixed without being aggregated.

The color of the colorant is basically determined by the chemical structure, and varies depending on factors such as the crystal structure, the size and shape of the particles. Many honeycomb base materials are yellowish yellow, yellowish white and yellowish brown, which are peculiar to ceramics. Accordingly, red, blue, green, black, purple, or an intermediate colorant is preferred for use in the present invention.
Dyes and pigments are sometimes used in dry colors that only contain dispersants, etc., but they can be processed into granules to form granular colors with improved scattering and contamination, or dispersed on the resin surface. In some cases, it may be used as a master powder adhered in a state of being applied, or a master batch in which a pigment is dispersed at a high concentration using a resin as a vehicle.

Colorants, that is, coloring materials (pigments) are roughly classified into dyes and pigments, and dyes are water-soluble, basic and acid, and oil-soluble, azo, anthraquinone, There are perylene-based ones.
As azo dyes, CI acid black 1, CI acid black 63, CI acid orange 7, CI acid orange 92, CI acid red 2, CI acid red 8, CI solvent brown 3, CI solvent orange 1, CI solvent red 1, CI Solvent yellow 7, CI solvent yellow 21, etc. are mentioned.
Examples of anthraquinone dyes include toluidine blue, C.I. I. Solvent Blue 11, 12, 35, 59, 74, 1-aminoanthraquinone, 2-aminoanthraquinone, hydroxyethylaminoanthraquinone, C.I. I. Solvent violet 47 may be mentioned. C. is a perylene dye. I. “DIMIC MBR 120830 Orange” manufactured by Dainichi Seika Kogyo Co., Ltd. consisting of Solvent Orange 55, “Lumogen F Yellow 083” manufactured by BASF, which is also a perylene dye, “Lumogen F Yellow 170” manufactured by BASF, which is a perylene imide dye. “Lumogen F Orange 240”, “Lumogen F Red 305”, C.I. I. Examples include “MBR D-75” manufactured by Dainichi Seika Kogyo Co., Ltd., which consists of Solvent Red197.

  Although the addition amount of the coloring dye is arbitrary, it is used in the range of 0.01 to 5% by mass relative to the whole composition. Although depending on the type of coloring dye, if the addition amount is small, the transparency of the resin is maintained, and if it is large, the opacity becomes strong.

  Food colorants may also be used such as tar color, caramel color, gardenia color, anthocyanin color, annatto color, paprika color, safflower color, red maple color, flavonoid color, cochineal color and the like.

  On the other hand, pigments are classified into inorganic pigments and organic pigments. As described above, there are many types of organic resins, and it is necessary to select an appropriate colorant according to the characteristics and physical properties of each resin. In the case of the present invention, the use of an inorganic pigment is not preferable in view of the influence on the catalyst performance, and the use of an organic pigment is desirable.

Organic pigments are classified into aniline black, azo pigments and polycyclic pigments.Azo pigments are monoazo pigments such as azo lake, Hansa and benzimidazolone, disazo pigments such as diarylide and virazolone, and yellow, There are condensed azo pigments such as red. On the other hand, examples of polycyclic pigments include phthalocyanine, quinacridone, perylene, perinone, dioxazine, anthraquinone, pyrrole, and isoindolinone pigments.
The aniline black is black, the azo lake is red, the benzimidazolone series is reddish yellow, the virazolone series is reddish yellow, and the red series is red. In addition, phthalocyanine series is blue-green, quinacridone series is red, perylene series is red, dioxazine series is purple, anthraquinone series is purple / red / blue, and pyrrole series is red. . Others are yellow, so it may be insufficient to identify the formation of the resin coating, but if the color of the honeycomb background is too different, it may be considered to impair the commercial value. It is also possible to select it, which is sometimes preferable.

  In selecting a colorant, consideration should be given to thermal stability. In the present invention, after the resin composition is applied, a step of drying and solidifying the honeycomb, further introducing a catalyst slurry into the cell, and subsequent drying and firing are added. The colorant must be present in the coating for identification after the resin coating has been applied to the honeycomb, but it may be desirable to be exposed to high temperatures to decompose and decolor after the final firing.

  In general, organic pigments often contain metal elements and thus have a lower heat resistance than dyes, and are often lower than inorganic pigments and carbon black. Aniline black, benzimidazolone series, diarylide series, virazolone series, yellow series, red series, perinone series, and dioxazine series have relatively high thermal decomposability, and azo lakes and hansa series are said to have higher thermal decomposability ( "Easy plastic compounding agent" supervised by the Japan Synthetic Resin Technology Association, published by Sanko Publishing Co., Ltd. on March 30, 1996, see page 43).

An azo lake pigment is an azo dye having a hydrophilic group such as a sulfonic acid group or a carboxylic acid group, which is water-insolubilized with sodium, barium, calcium, strontium, manganese, aluminum, or other metal ions. . I. Pigment Red 57, 53, 52, 49, 64, 50, 63, 60, 58, 151, 243, etc., C.I. I. Pigment orange 17 etc., C.I. I. Pigment Yellow 168 and the like are azo lake pigments such as oxynaphthoic acid type, naphthol type, acetoacetate anilide type, and the like, and methods for producing such azo lake pigments themselves are known.
The azo lake pigment is produced by coupling with a metal salt using an aqueous solution containing a coupler component composed of phenol / naphthol and an aqueous solution containing a diazonium salt component of an aromatic amine. In the above production method, an azo lake pigment treated with rosins is also obtained by including a metal salt of rosins in the system before the start of each reaction, during the reaction, or at any stage after the reaction.
Although the amount of the pigment-based colorant used depends on the type, it is preferable that the amount of the pigment-based colorant be 1% by mass or less based on the resin composition as long as the discrimination effect can be confirmed. If it exceeds the above range, the appearance of the honeycomb surface may be impaired after the catalyst is formed. More preferred is 0.1% by mass or less.

In addition to water and the colorant, the resin component can appropriately include a resin varnish, a thickener, a wetting agent, a curing agent, a stabilizer, and the like.
Examples of the resin varnish include an aqueous shellac varnish, an aqueous casein varnish, an aqueous rosin maleic resin varnish, an aqueous polyester resin varnish, and a water-soluble cellulose varnish.
Examples of the thickener include methyl cellulose, hydroxyethyl cellulose, and urethane resin, examples of the wetting agent include alkyl alcohol ethylene oxide adducts, and examples of the film forming aid include 2, 2 , 4-trimethyl-1,3-pentanediol, dipropylene glycol n-butyl ether, propylene glycol n-butyl ether, polypropylene glycol monomethyl ether, and the like.

Hereinafter, a specific embodiment of the colored resin coating on the honeycomb substrate will be described.
FIG. 3 schematically shows an example in which two driving / coating rollers are arranged, a honeycomb base material is placed thereon, and the coating liquid is attached to the circumferential side surface by being rotated by the rollers.

First, the honeycomb structure (2) is placed on a drive / application roller (1) having a lower end immersed in a liquid bath (3) in which a coating liquid containing an organic material is stored. Contact the circumferential side of 2). As the driving / coating roller, it is preferable that the outermost surface of the roller is formed in a sponge shape.
In order to supply the application liquid to the drive / application roller, for example, it is preferable to immerse at least the outermost sponge-like material portion of the roller in a container filled with the application liquid. When two or more drive / application rollers are used, the application liquid may be supplied to only one of them, or the application liquid may be supplied to both.

Moreover, in the embodiment of FIG. 4, two drive rollers (6) are used, and a honeycomb structure (2) is mounted thereon. Then, the honeycomb structure (2) is rotated by the lower drive roller (6), and the application liquid is adhered by the application roller (5) from the upper part of the honeycomb structure (2).
In this aspect, unlike the above aspect, after the coating liquid is supplied from above and adheres to the honeycomb structure, the surplus falls down below the driving roller. Therefore, although not shown, a pipe or the like for dropping the application liquid in a shower shape along the roller is arranged above the application roller to supply the application liquid, and a receiving tray for the application liquid is provided at the bottom. In the case of a coating liquid having high fluidity, the liquid accumulated in the tray can be circulated to the upper part. You may use what built the said pipe in the core part of the roller.
Alternatively, a separate liquid bath may be provided, and the application roller may be moved to the liquid bath each time to wet the required application amount and then be positioned at the top.

Thereafter, when the drive / application roller (1) or the drive roller (6) is driven and rotated, the honeycomb structure (2) also rotates. When at least one rotation is made, the drive / application roller (1) or the application roller (5) The adhering organic coating liquid is coated on the entire outer periphery of the honeycomb structure (1). The organic resin component contained in the emulsion liquid undergoes centrifugal force during rotation, and there is also a part that enters the macropore from the outer skin part.
In this case, the rotation speed of the drive / application roller is preferably 0.1 to 100 rpm, for example, although it depends on the size of the roller used and the type of the resin material. The smaller the rotation speed, the greater the amount of coating liquid adhering to the outer skin portion of the honeycomb structure and the permeation amount into the pores, and the macro pores penetrating the outer skin portion are sufficiently enclosed. In the present invention, the rotation speed is reduced or the roller is pressed against the honeycomb substrate to increase the amount of penetration from the honeycomb structure skin portion into the cell, and the liquid overflows from the pores and adheres to the inner cell wall deeply. It is preferable to do so.

  When a resin component dissolved or dispersed in a solvent is used in the coating solution, the honeycomb structure coated with the coating solution is then moved to a drying (curing) step. The drying (curing) step is not particularly limited, but may be performed at a temperature of 0 to 200 ° C. under atmospheric pressure or reduced pressure, and is preferably performed at room temperature. If necessary, air or inert gas may be applied to the surface or the pressure may be reduced. Although heating changes with kinds of resin, the temperature of 50-200 degreeC is preferable and it is more preferable to carry out at 100-180 degreeC.

As a result, if the thermosetting resin monomer is acrylic or the like, the monomer is polymerized to become a cured product, and if polyvinyl alcohol or the like is solidified due to a decrease in moisture, the coated honeycomb structure is obtained.
By adopting the honeycomb structure of the present invention, the method of the present invention using a combination of a roller and a coating liquid, the pores of the porous body in the outer skin portion are reduced to such an extent that the slurry does not leach out from the outer skin portion during wash coating. At the same time, it is possible to obtain a coating that disappears due to heat during catalyst production but does not adversely affect the catalyst.

4). Resin-coated honeycomb structure The resin-coated honeycomb structure of the present invention is obtained by forming a colored resin coating on at least a part of the outer surface of the outer wall portion.

The colored resin can be provided over the entire surface of the outer skin of the honeycomb structure, and at least a part of the colored resin is preferably enclosed in large pores that penetrate the outer wall.
The coating of the organic material on the surface of the outer skin is not limited by the thickness, but is preferably 0.1 mm or less. If it is too thin, the amount of the encapsulated pores may be reduced and the catalyst component-containing liquid may easily ooze out to the outer periphery. If it is too thick, the material remains in the firing step of supporting the catalyst on the honeycomb structure and the surface condition is deteriorated. However, if it is reasonably thick, when the coating is formed, when the slurry containing the catalyst component is sealed in large pores that penetrate the outer wall, the liquid material overflows inside the cell and covers the inner wall. Although it becomes difficult to be supported, it is preferable to stay in the outermost or further inner cell in order to increase the strength of the honeycomb skin.

In the present invention, it is desirable that the organic material has a thin film uniformly formed on the outer surface of the honeycomb. If the surface is too thin and uneven, the amount of sealing in the large pores will be insufficient and the slurry will ooze out from the inside, and if it is too thick, the resin will remain in the subsequent baking and the appearance will deteriorate.
In the coating, the organic resin as the main component disappears by calcination during the production of the catalyst, and does not adversely affect the outflow of exhaust gas from the outer skin of the catalyst.
The resin solution must be one that disappears upon firing during the production of the catalyst and does not adversely affect the catalyst. For this purpose, organic materials are preferably used, and those having relatively low heat resistance, such as those that decompose and dissipate at low temperatures, are useful as colorants.

By blending the colorant into the resin composition in the present invention, the degree of application of the resin composition to the honeycomb substrate can be grasped, and the excess or deficiency of the resin coating can be estimated. Concerns about leaching and the occurrence of thermal shock can be avoided.
The resin-coated honeycomb structure of the present invention is suitably used, for example, as an exhaust gas purifying catalyst for automobiles, and can prevent the catalyst slurry from leaching to the outer wall when applying the washcoat method, When used as a filter (GPF), the air permeability of the outer wall can be secured without adverse effects.

5. TECHNICAL FIELD The present invention relates to a honeycomb structure type catalyst having a step of coating the cell partition wall with a wash coating method including a pressurizing step, using the resin-coated honeycomb structure. It is a manufacturing method.

  For example, in a gasoline vehicle exhaust gas purification catalyst using a resin-coated honeycomb structure, a catalyst component of a three-way catalyst (TWC) that purifies NOx, CO, and hydrocarbons is supported in cells of the honeycomb structure carrier. A three-way catalyst (TWC) is an exhaust gas purification catalyst in which an active component mainly composed of noble metals such as platinum, palladium, and rhodium is supported on inorganic oxide particles, and is a carbonization that is a harmful substance contained in the exhaust gas. Regarding hydrogen, carbon monoxide, and nitrogen oxides (NOx), hydrocarbons are oxidized to water and carbon dioxide, carbon monoxide is oxidized to carbon dioxide, and nitrogen oxides are reduced to nitrogen and purified at once. A composition containing such a catalyst component is made into a slurry and coated on the resin-coated honeycomb structure of the present invention using a known wash coat method, and dried and fired to support the catalyst component.

In the wash coating method, the outer peripheral portion of the honeycomb filter carrier is held by an elastic holding jig (also referred to as “balloon”), and a slurry liquid bath containing a catalyst component of a three-way catalyst (TWC) is covered and supported. In the filter catalyst (DPF) for diesel vehicles, since the exhaust gas speed is not so high, the outer shell is made of a dense structure different from the material constituting the filter cell, and the mechanical strength of the honeycomb structure is increased. Often planned. For this reason, the problems of bleeding of the slurry liquid and sticking when a balloon is used, which are problems in the present invention, do not occur.
However, in GPF, a honeycomb-like filter is used to remove the fine particulate matter contained in the exhaust gas of a gasoline vehicle, so there are large pores on the outer wall, and these are from the inside of the cell to the outside. There are also places that communicate. In such a part, the slurry liquid is likely to ooze out from the outer space. Since the present invention uses the honeycomb structure described above, the catalyst component-containing liquid does not easily exude to the outer periphery of the honeycomb structure in the step of coating the catalyst component of the three-way catalyst (TWC) in the cell, and the adhesive component It prevents sticking to the elastic gripping jig by the liquid containing, and does not hinder the detachment work.

The noble metal is supported on particles such as alumina, and is supported on the honeycomb in one or two layers by a slurry containing the noble metal. The particle size of the slurry is preferably small, and 90% is preferably 5 μm or less, more preferably 3 μm or less. The amount of the three-way catalyst (TWC) is preferably in the range of 40 to 150 g / L, more preferably 50 to 100 g / L in terms of the coating amount per 1 L of the honeycomb volume.
In addition, oxides containing elements such as zirconia, ceria, La, Nd, and Pr can be blended as components that improve heat resistance and components that store and release oxygen.

The components of the slurry also include a sticky substance that makes it easy to deposit the catalyst material in the cell, which also causes sticking when a balloon is used to hold the honeycomb structure in the washcoat method. Yes. With the resin-coated honeycomb structure obtained by the present invention, such sticking can be avoided.
Further, in the case of a honeycomb structure type catalyst obtained by wash coating and drying (curing) firing using the resin-coated honeycomb structure obtained by the present invention, the outer skin portion is heated by heating at 400 ° C. or higher in the production process. By burning out the resin coating, it is possible to reduce the inorganic oxide particles contained in the outer skin part, and suppress the occurrence of thermal shock due to thermal history during catalyst production and when running as an actual vehicle You can also.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples as long as the gist thereof is not exceeded.

A cordierite wall flow honeycomb structure manufactured by NGK was prepared as a honeycomb substrate. The details are as follows.
・ Porosity: 65% by volume on both outer wall and partition wall
・ Average pore diameter: 20 μm in volume average by mercury porosimetry
-Partition wall thickness: 10 [mil (about 0.3 mm)]
Cell density: 300 [cel / inch ² (about 46.5 cel / cm ² )]
・ Diameter: 4.66 [inch (118.4 mm)]
・ Length: 5 [inch (127 mm)]

[Comparative Example 1]
Polyvinyl alcohol (PVA) having an average degree of polymerization of 1900 was dissolved in water to prepare a 5% by mass resin composition solution as a resin coating forming solution.
This resin coating forming liquid was applied to the outer surface of the outer peripheral wall of the honeycomb substrate so as to be 10 g / L using an apparatus having rollers as shown in FIG. 3, and then dried.
As shown in the photograph in the upper right of FIG. 2 (B / C), discoloration due to the adhesion of the resin was confirmed on the surface of the honeycomb substrate after application, but the lower right (B / D) of FIG. 2 after drying. As shown in the photo, it faded and became a honeycomb surface.
Because the application time was short, the resin adhesion part did not become the whole area of the honeycomb substrate, and the resin coating became non-uniform. There was concern that the catalyst slurry would ooze out.
Therefore, the pressure for pressing the roller against the outer peripheral wall of the honeycomb substrate, the number of rotations of the roller, and the like were controlled so that the amount of the resin composition applied to the honeycomb substrate was larger than the above. The coating amount (impregnation depth from the outer peripheral wall side) is confirmed visually from both end faces of the honeycomb, and it is confirmed that the liquid for forming the outer skin layer is impregnated to the depth of one cell inside the outer peripheral wall axial direction, The honeycomb structure was dried.
On the surface of the honeycomb substrate after coating, as shown in the photograph in the upper left of FIG. 2 (AC), discoloration was confirmed over the entire surface, but after drying, the photograph in the lower left of FIG. 2 (AD). Like, it faded and became the background of the honeycomb.
In any of the above cases, there is a problem that it is not possible to identify whether or not the honeycomb base material is suitable for use in the next catalyst manufacturing process only by visual observation of the dried honeycomb substrate.

[Example 1]
(Impregnation of resin composition into honeycomb substrate)
First, polyvinyl alcohol (PVA) having an average degree of polymerization of 1900 is dissolved in water together with a purple pigment (trade name: powdered food pigment purple, manufacturer: My Kitchen Co., Ltd.), and a resin composition solution of 5% by mass is formed as a resin coating. Prepared as a working solution.
This resin coating forming liquid was applied to the entire outer surface of the outer peripheral wall of the honeycomb substrate so as to be 15 g / L.
The coating amount (impregnation depth from the outer peripheral wall side) is confirmed visually from both end faces of the honeycomb, and it is confirmed that the liquid for forming the outer skin layer is impregnated to the depth of one cell inside the outer peripheral wall axial direction, The honeycomb structure was dried. The coating forming solution was applied using a roller, and the amount applied was controlled by the pressure with which the roller was pressed against the outer peripheral wall of the honeycomb substrate, the number of rotations of the roller, and the like.
As shown in the upper right (B / C) photograph of FIG. 1, the surface of the honeycomb substrate after coating was confirmed to be colored, and even after drying, as shown in the lower right (B / D) photograph of FIG. It was blue. This facilitates identification of the honeycomb substrate used in the catalyst manufacturing process.
However, since the colored portion was localized on the honeycomb substrate, it can be assumed that the resin coating became non-uniform, and using this, there is a concern that the catalyst slurry may ooze out from the area where the resin is not coated in the catalyst manufacturing process. It was.

Therefore, although it is the same as the above, the contact condition with the roller was controlled so that the amount of the resin composition applied to the honeycomb substrate was increased. The PVA as the resin composition was impregnated in all of the outer peripheral wall and the partition walls, and no PVA single layer was formed on the outer peripheral wall surface. However, the surface of the honeycomb base material after coating can be confirmed to be uniformly colored as shown in the upper left (A / C) photograph of FIG. As shown in the lower left (A / D) picture of FIG.
In addition, PVA which is a resin composition impregnates the whole area of the outer peripheral wall and a part of the partition wall, and a remarkable PVA single layer was not formed on the outer peripheral wall surface. In the process, it was judged that the exudation of the catalyst slurry could be suppressed by the resin coating.

(Manufacture of honeycomb structure type catalyst)
Thereafter, the wall flow honeycomb structure thus provided with the appropriate coating layer is coated with the catalyst composition slurry containing the three-way catalyst Rh, Pd, alumina, ceria, zirconia under the following conditions by the wash coat method. did.
D90 when the cumulative distribution from the small particle size side in the particle size distribution is 90%: 3 μm
-Wash coat amount per unit volume of honeycomb: 60 [g / L]
-Air blow pressure in the slurry removal step: 15 (0.1) [psi (MPa)]
・ Air blow time: 3 [seconds]
When the appearance of the obtained catalyst was seen, the leaching of the catalyst composition slurry and the generation of cracks on the outer peripheral wall were completely suppressed.
Moreover, PVA which is a resin composition disappeared by heating in the baking process, and most of the colorant was decomposed therewith, and the color on the outer peripheral wall surface was considerably thin and did not impair the commercial value. .

[Example 2]
As a resin composition to be applied to the wall flow honeycomb structure used in Example 1, a water emulsion type of acrylic resin is used, and a colorant is blended. As in Example 1, a blue resin film is applied to the honeycomb substrate. Formed.
Although the coating conditions were the same, the surface of the honeycomb substrate after coating was entirely vividly colored. This is probably because the acrylic resin of the resin component was polymerized by drying and was impregnated in the outer peripheral wall and the partition walls.
If this was used, it could be judged that in the catalyst production process, exudation of the catalyst slurry could be suppressed by resin coating.
Thereafter, the slurry composition containing Rh, Pd, alumina, ceria, and zirconia as three-way catalysts is applied to the wall flow honeycomb structure thus provided with the resin coating layer by the wash coat method under the same conditions as in Example 1. Was coated.
The appearance of the obtained catalyst, that is, the leaching of the catalyst composition slurry on the outer peripheral wall and the occurrence of cracks were observed, but the leaching of the catalyst composition slurry and the occurrence of cracks were completely suppressed. In addition, PVA, which is a resin composition, almost disappeared by heating in the baking step, and a slight coloration on the outer peripheral wall surface remained, but it did not reduce the commercial value.

[Example 3]
Example 1 with the exception that the resin composition to be applied to the wall flow honeycomb structure used in Example 1 was 8 g / L of a brown acrylic resin (“water-based varnish mahogany” manufactured by Washin Paint Co., Ltd.). Similarly, a honeycomb structure type catalyst was obtained.
The appearance of the obtained catalyst, that is, the leaching of the catalyst composition slurry on the outer peripheral wall and the occurrence of cracks were observed, but the leaching of the catalyst composition slurry and the occurrence of cracks were completely suppressed. Further, the acrylic resin as the resin composition almost disappeared by heating in the baking step, and a slight coloration on the outer peripheral wall surface remained, but it did not reduce the commercial value.

[Example 4]
A resin composition to be applied to the wall flow honeycomb structure used in Example 1 was changed to a black wax (“is-fit (registered trademark) liquid shoe cream” manufactured by Morito Co., Ltd.) 15 g / L. In the same manner as in Example 1, a honeycomb structure for producing a catalyst having a resin composition in the outer skin portion was obtained.
The appearance of the obtained catalyst, that is, the leaching of the catalyst composition slurry on the outer peripheral wall and the occurrence of cracks were observed, but the leaching of the catalyst composition slurry and the occurrence of cracks were completely suppressed. Further, the wax as the resin composition almost disappeared by heating in the baking step, and a slight coloration on the outer peripheral wall surface remained, but it did not reduce the commercial value.

The resin-coated honeycomb structure of the present invention is provided with the colored resin coating, thereby confirming the completion of the coating on the outer surface of the outer wall and the penetration of the resin to an appropriate depth into the outer wall of the honeycomb structure. Since it is easy, the resin-coated honeycomb structure can be manufactured stably and inexpensively, and mass production is possible.
Further, the coating of the resin-coated honeycomb structure can prevent the catalyst slurry from leaching to the outer wall portion, particularly when the washcoat method is applied. Therefore, when used as a honeycomb carrier of a GPF of a gasoline vehicle, the air permeability of the outer wall portion can be ensured.

1 Drive and application roller
2 Honeycomb substrate 5 Application roller 6 Driving roller

Claims (12)

A honeycomb substrate made of a porous inorganic oxide and having partition walls for partitioning a plurality of cells extending from an inlet end surface serving as a fluid inlet side to an outlet end surface serving as a fluid outlet side, and an outer wall serving as a side surface; ,
A resin-coated honeycomb structure comprising a colored resin coating formed on an outer surface of the outer wall portion.   In the outer surface of the outer wall portion on which the resin coating is formed, at least a part of the hole before the resin coating is formed is sealed or the opening size of the hole is narrowed by the resin coating. The resin-coated honeycomb structure according to claim 1.   The honeycomb substrate has a filter structure having a plugging portion that plugs an opening end portion on the inlet end face side of a predetermined cell and an opening end portion on the outlet end face side of a remaining cell. The resin-coated honeycomb structure according to claim 1 or 2.   A honeycomb substrate made of a porous inorganic oxide and having partition walls for partitioning a plurality of cells extending from an inlet end face serving as a fluid inlet side to an outlet end face serving as a fluid outlet side, and an outer wall serving as a side surface. The method for producing a resin-coated honeycomb structure according to any one of claims 1 to 3, wherein a resin coating containing a colorant is applied and then dried and cured to form a resin coating.   The method for producing a resin-coated honeycomb structure according to claim 4, wherein the resin solution contains at least one resin selected from polyvinyl alcohol (PVA) and acrylic resin.   The resin-coated honeycomb structure according to claim 5, wherein the resin is polyvinyl alcohol (PVA), and is used as an aqueous solution having an average degree of polymerization of 1500 to 3000 and a concentration of 3 to 10% by mass. Method.   The method for producing a resin-coated honeycomb structure according to any one of claims 4 to 6, wherein the resin coating disappears by heat of 400 ° C or higher.   Using the resin-coated honeycomb structure according to any one of claims 1 to 3, the cell partition walls of the honeycomb structure are coated with a catalyst composition slurry by a wash coating method including a pressurizing step. A method for producing a honeycomb structure type catalyst.   The honeycomb structured catalyst according to claim 8, further comprising a step of firing the resin-coated honeycomb structure after being coated with the catalyst composition slurry, and at least a part of the color disappears together with the resin coating by the firing. Manufacturing method.   The method for producing a honeycomb structured catalyst according to claim 8 or 9, wherein the catalyst composition slurry contains at least one noble metal element selected from Pt, Pd and Rh.   A honeycomb structure-type catalyst obtained by the method according to any one of claims 8 to 10, wherein the outer surface of the outer wall portion is substantially free of a catalyst composition and has air permeability.   The honeycomb structure type catalyst according to claim 11, which is used as a gasoline particulate filter (GPF).