WO2020044228A1

WO2020044228A1 - Holding material and method of manufacturing same, and pollution control apparatus

Info

Publication number: WO2020044228A1
Application number: PCT/IB2019/057200
Authority: WO
Inventors: Kenji Sako
Original assignee: 3M Innovative Properties Company
Priority date: 2018-08-30
Filing date: 2019-08-27
Publication date: 2020-03-05
Also published as: JP2020033935A

Abstract

A holding material including a surface that is easy to be wound around an outer peripheral surface of a pollution control element at the manufacturing step of a pollution control apparatus and that can improve holding force. The holding material including, a main body portion having a sheet-like shape and including at least a first inorganic fiber, a first region provided on at least one surface of the main body portion and where a first material including at least an inorganic material is attached to the first inorganic fiber, and a part in which, along a winding direction of the main body portion, the first region and a second region are interleaved with each other, and the first region is not attached to the second region or is attached to the second region with fewer attachment amount than to the first region.

Description

HOLDING MATERIAL AND METHOD OF MANUFACTURING SAME, AND POLLUTION

CONTROL APPARATUS

TECHNICAL FIELD

The present disclosure relates to a holding material and a method of manufacturing the same, and a pollution control apparatus.

BACKGROUND ART

Exhaust gas from an automobile engine includes carbon monoxide (CO), hydrocarbon (HC), nitrogen oxide (NOx), and the like. Exhaust gases discharged from a diesel engine also include particulate matters such as soot. As means for removing these, an exhaust gas cleaning system using a ceramic catalytic converter or a diesel particulate filter (DPF) is known.

Furthermore, installation of a gasoline particulate filter (GPF) has also been studied. These devices are commonly referred to as pollution control apparatuses.

In general, a pollution control apparatus (for example, a ceramic catalytic converter) comprises a pollution control element (for example, a honeycomb-shaped ceramic catalyst support), a metal casing that houses the pollution control element, and a holding material that fills a gap between an outer peripheral surface of the pollution control element and an inside surface of the casing. The holding material holds the pollution control element within the casing and prevents a mechanical shock due to an impact, vibration, and the like from inadvertently being applied to the pollution control element. The holding material prevents movement and destruction of the pollution control element within the casing and provides a desirable effect in the operation lifetime of the pollution control element. This type of holding material is also commonly referred to as a mounting material. These holding materials are normally in the form of a mat made of a single layer or a plurality of layers, and are used by winding around a pollution control element.

Patent JP 10-337480 A discloses a catalytic converter comprising a monolith on which a catalyst is supported, a casing housing the monolith, and a holding material interposed in a gap between the monolith and the casing, wherein a large number of grooves orthogonal to a winding direction of the holding material are provided on a surface of the holding material on the side that is in contact with the monolith. According to Patent JP 10-337480 A, a large number of the grooves on a specific surface of the holding material are provided, the holding material can be wound easily on the monolith and the adhesion of the holding material to the monolith can be further enhanced (see 0037 of Patent JP 10-337480 A). Patent JP 2007-332922 A discloses a holding sealant including a groove-shaped structure on a specific surface. Patent JP 2017-31869 A discloses a holding sealant including a surface on which lattice-like grooves are formed. SUMMARY OF INVENTION

An object of the present disclosure is to provide a holding material including a surface that is easy to be wound around an outer peripheral surface of a pollution control element at the manufacturing step of a pollution control apparatus, and that can improve holding force.

Furthermore, an object of the present disclosure is to provide a method of manufacturing a holding material and a pollution control apparatus including a holding material.

A holding material according to the present disclosure is a holding material wound on an outer peripheral (e.g., circumferential, oval, etc.) surface of a pollution control element, the holding material including, a main body portion having a sheet-like shape and including at least a first inorganic fiber, a first region provided on at least one surface of the main body portion and where a first material including at least an inorganic material is attached to the first inorganic fiber, and a part in which, along a winding direction of the main body portion, the first region and a second region are interleaved with each other, and the first region is not attached to the second region or is attached to the second region with fewer attachment amount than to the first region.

A pollution control apparatus according to one aspect of the present disclosure includes a casing, a pollution control element disposed within the casing, and the holding material disposed between the casing and the pollution control element.

A method of manufacturing a holding material according to one aspect of the present disclosure includes the steps of preparing a main body portion of a holding material, and providing a first region on at least one surface of the main body portion.

According to the present disclosure, provided is a holding material including a surface that is easy to be wound around an outer peripheral surface of a pollution control element at the manufacturing step of a pollution control apparatus and that can improve holding force.

Furthermore, according to the present disclosure, a method of manufacturing a holding material and a pollution control apparatus including a holding material are provided.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view illustrating an embodiment of a holding material according to the present disclosure.

FIG. 2 is a schematic cross-sectional view along line II-II in FIG. 1.

FIG. 3 is a cross-sectional view schematically illustrating an embodiment of a pollution control apparatus according to the present disclosure.

FIGS. 4A to 4C are top views each illustrating another embodiment of a holding material.

FIGS. 5 A to 5 C are top views each illustrating another embodiment of a holding material.

FIG. 6 is a cross-sectional view schematically illustrating an apparatus for measuring a coefficient of static friction of a holding material. DESCRIPTION OF EMBODIMENTS

The holding material according to the present disclosure is a holding material wound on an outer peripheral (e.g., circumferential) surface of a pollution control element, the holding material including, a main body portion having a sheet-like shape and including at least a first inorganic fiber, a first region provided on at least one surface of the main body portion and where a first material including at least an inorganic material is attached to the first inorganic fiber, and a part in which, along a winding direction of the main body portion, the first region and a second region are interleaved with each other, and the first region is not attached to the second region or is attached to the second region with fewer attachment amount than to the first region. According to the holding material according to the present embodiment, the first region where at least the inorganic material is attached improves a coefficient of static friction or impart adhesiveness, and thus can contribute to improvement of holding force. Furthermore, for example, even when the first region is harder as compared to the second region, since the first region and the second region are interleaved with each other in the winding direction, the ease of winding around an outer peripheral surface of a pollution control element can be maintained sufficiently.

Detailed description of embodiments of the present disclosure will be given below with reference to the drawings.

FIG. 1 is a perspective view illustrating an example of a holding material. FIG. 2 is a schematic cross-sectional view along line II-II in FIG. 1. The holding material 10 is for winding around a pollution control element 30 having a shape of a cylinder or elliptical column and holding the pollution control element 30 in a casing 20 (see FIG. 3). The holding material 10 has a length corresponding to a length of an outer periphery of the pollution control element 30. The holding material 10 includes, for example, a convex portion lOa at one end and a concave portion lOb at the other end, is formed in a shape such that the convex portion lOa and the concave portion lOb mate with each other when the holding material 10 is wound around the pollution control element 30. Note that the shape and the like of the mating are not particularly limited, and other forms such as an F-shape can be used.

The holding material 10 includes a main body portion 1 having a sheet-like shape, a first region Rl provided on a surface Fl of the main body portion 1, and a second region R2 between two first regions Rl . The main body portion 1 having a sheet-like shape includes at least a first inorganic fiber. The first region Rl is a region where the first material adheres to the first inorganic fibers constituting the main body portion 1. The second region is a region where the first material is not attached or is attached with fewer attachment amount than the first region Rl . The first region Rl and the second region R2 are present interleaved with each other along the winding direction of the main body portion 1 (a direction of arrow A as illustrated in FIG. 1).

In the present embodiment, as illustrated in FIG. 1, the first region Rl is formed to make a striped pattern. Namely, the first region Rl is formed to make a regular pattern in the surface Fl, and both the first region Rl and the second region R2 are formed continuously from one end to the other end in the width direction of the main body portion 1 (a direction orthogonal to the direction of arrow A). The width and pitch of the stripes may be set appropriately according to the size of the holding material 10 or flexibility required for the holding material. According to the study of the present inventors, when the first region Rl is stripe-shaped, an area proportion of the first region Rl based on the area of the surface Fl may be, for example, 15 to 90%, or 15 to 80%, or 20 to 70%.

The main body portion 1 mainly includes an inorganic fiber (first inorganic fiber). The thickness of the main body portion 1 is, for example, approximately 5 to approximately 15 mm. Specific examples of the inorganic fiber constituting the main body portion 1 include glass fibers, ceramic fibers, carbon fibers, silicon carbide fibers, and boron fibers, and other inorganic fibers may be used as necessary. One type of the inorganic fiber selected from the above may be used alone, or a combination of two or more types thereof may be used, or a composite fiber thereof may be used. Among these, particularly preferred are ceramic fibers such as alumina fibers, silica fibers, and alumina-silica fibers. The ceramic fibers may be used alone, or a combination of two or more types thereof may be used, or composite fibers thereof may be used.

The main body portion 1 is obtained by mixing inorganic fibers and an organic binder as starting materials with any additives, and then continuously performing the steps such as spreading the inorganic fibers, preparing a slurry, molding by papermaking, and mold pressing. WO

2004/061279 and US 6051193 can be referred to for details of a wet method (wet lamination method). Note that the type of the organic binder and the amount of the organic binder used are not particularly limited. For example, acrylic resins, styrene -butadiene resins, acrylonitrile resins, polyurethane resins, natural rubbers, polyvinyl acetate resins, and the like provided in the form of latex can be used as the organic binder. Alternatively, a flexible thermoplastic resin such as an unsaturated polyester resin, an epoxy resin, and a polyvinyl ester resin may be used as the organic binder.

The first region Rl is a region where the first material is attached to the inorganic fiber of the main body portion 1. The unit area amount of the first material present in the first region Rl may be, for example, 1 to 50 g/m², 2 to 40 g/m², or 5 to 30 g/m². The amount of the first material in the first region Rl may be set as appropriate in accordance with the size of a coefficient of static friction or adhesiveness required of the holding material 10. The first material includes at least an inorganic material. Examples of the inorganic material include inorganic particles, inorganic fibers (second inorganic fibers), and inorganic adhesives. One type of these materials may be used alone, or two or more types thereof may be used in combination.

Examples of inorganic particles include metal oxide, nitride, and carbide particles.

Preferred examples of metal oxide having heat resistance include, but are not limited to, silica, alumina, mullite, zirconia, magnesia, and titania. Examples of other suitable materials may include boron nitride and boron carbide. One type of the particles made from these materials may be used alone, or two or more types thereof may be used in combination.

The inorganic particles can be used with a variety of particle sizes in response to the type of inorganic material and a desired friction improving effect. It is usually preferred that the inorganic particles have an average particle size of approximately 1 to 100 nm. When the average particle size of the inorganic particles is 1 nm or greater, a friction increasing effect is exhibited.

On the other hand, when the average particle size of the inorganic particles is less than or equal to 100 nm, a friction increasing effect is exhibited, and the peeling off of the inorganic particles from the main body portion 1 can be suppressed sufficiently. The average particle size of the inorganic particles is more preferably within the range of approximately 10 to 80 nm, and more preferably in the range of approximately 20 to 50 nm. For the inorganic particles (inorganic colloidal particles), reference can be made to WO 2007/030410.

Examples of an inorganic fiber (second inorganic fiber) include metal oxide, nitride, and carbide fibers. The diameter of the inorganic fiber may be approximately 1 nm to approximately 15 nm, and for example, may be approximately 1 nm or greater, approximately 2 nm or greater, or approximately 3 nm or greater, and approximately 15 nm or less, approximately 8 nm or less, or approximately 5 nm or less. An inorganic fiber having a diameter of approximately 1 nm or greater is advantageous in that the inorganic fiber is more readily available as compared to a thinner inorganic fiber. In addition, at the time of manufacturing a pollution control apparatus, there is a tendency that scattering of the fiber pieces can be suppressed. On the other hand, there is a tendency that an inorganic fiber having a diameter of approximately 15 nm or less can suppress the generation of the fiber pieces as compared to a thicker inorganic fiber at the time of manufacturing a pollution control apparatus. The average length of the inorganic fiber may be, for example, approximately 500 to approximately 5000 nm, and may be approximately 1000 to approximately 4000 nm or approximately 1400 to approximately 3000 nm.

The diameter (average diameter) and the average length (average fiber length) of the inorganic fiber can be determined by measuring the thickness and the length of randomly extracted fibers from, for example, 50 or more micrograph images (TEM image, SEM image, and the like), and calculating the average values of the thicknesses and the lengths. The aspect ratio of the inorganic fiber is calculated by dividing an average length value by a value of the diameter.

The second inorganic fiber may have a different aspect ratio from the first inorganic fiber constituting the main body portion 1. The aspect ratio of the second inorganic fiber may be, for example, approximately 60 to approximately 2000, and may be approximately 100 to

approximately 1500, or approximately 300 to approximately 800. An inorganic fiber having an aspect ratio of approximately 60 or greater has a tendency to be capable of suppressing scattering of the fiber pieces as compared to an inorganic fiber having a smaller aspect ratio at the time of manufacturing a pollution control apparatus. On the other hand, an inorganic fiber having an aspect ratio of approximately 2000 or less is more readily available as compared to an inorganic fiber having a larger aspect ratio. For the inorganic fiber, reference can be made to the specification of JP 2017-210815.

The inorganic adhesive is a material that expresses adhesiveness by being heated. The inorganic adhesive not only includes the inorganic adhesive that adheres due to a product formation reaction with other members, but also the inorganic adhesive that exhibits fluidity by heating, penetrates into a surface of the other member which is a contact surface, and generates adhesion by an anchoring effect (anchoring state). Although the temperature at which the adhesiveness is expressed is not limited, the adhesiveness may be expressed at a temperature of, for example, 200°C or greater, or 300°C or greater, or 600°C or greater. For example, when the holding material 10 is placed in a state interposed between two members, and after the holding material 10 is left under a temperature condition of 600°C for one hour, the holding material 10 expresses adhesiveness to other members. Adhesiveness is expressed, and thus substantial holding force of the holding material 10 can be improved effectively.

Examples of the inorganic adhesive include at least one type of salt selected from the group consisting of alkali metal salts, alkaline earth metal salts, and phosphate salts. Specific examples of the alkali metal salts include alkali metal silicates such as sodium silicate, potassium silicate, and lithium silicate. Specific examples of the alkaline earth metal salts include alkaline earth metal silicates such as magnesium silicate and calcium silicate. Specific examples of phosphate salts include aluminum phosphate, magnesium phosphate, and calcium phosphate. One type of these components may be used alone, or two or more types thereof may be used in combination.

The first material may further include an organic binder. Examples of the organic binder include an acrylic resin, a styrene-butadiene resins, an acrylonitrile resin, a polyurethane resin, natural rubber, and a polyvinyl acetate resin provided in the form of latex. Alternatively, a flexible thermoplastic resin such as an unsaturated polyester resin, an epoxy resin, and a polyvinyl ester resin may be used as the organic binder. Note that, there is a tendency that scattering of the fiber pieces can be suppressed by the first material including the organic binder.

The color of the first region Rl may be different from the color of the second region R2 in view of visibility. For example, blending ink into a liquid for forming the first region Rl enables the first region Rl to become visible. Alternatively, the first region Rl may contain a material that emits light by irradiation with black light. In this case, it is easy to confirm whether or not the first regions Rl are formed by using the black light in the inspection step after manufacturing the holding material 10.

The method of manufacturing the holding material 10 includes the steps of preparing the main body portion 1 and providing the first region Rl on at least one surface Fl of the main body portion 1. According to the manufacturing method described above, the holding material 10 having the first region Rl formed on at least one surface Fl of the main body portion 1 can be obtained.

Note that when a mat made of inorganic fibers including an organic binder and/or inorganic fine particles is used as the main body portion 1, the following steps may be performed prior to the formation of the first regions Rl .

(a) The step of impregnating a mat made of inorganic fibers with a colloidal solution containing an organic binder and/or inorganic fine particles.

(b) The step of obtaining the main body portion 1 by drying the mat impregnated with the colloidal solution.

At step (a), in a case where the inorganic fine particles are present inside the mat, the composition of the colloidal solution is preferably adjusted such that the amount of the inorganic fine particles is approximately 1 to approximately 10 mass% based on the total mass of the main body portion 1. When the amount of the inorganic fine particles is approximately 1 mass% or greater, a sufficient surface pressure is easily obtained, and when the amount of the inorganic fine particles is approximately 10 mass% or less, sufficient flexibility is easily obtained to wind the holding material 10 around the pollution control element.

It is sufficient that the mat obtained at step (a) can be dried at step (b). For example, the mat obtained at step (a) may be dried in a hot air drier set to approximately 80 to approximately 250°C for approximately 10 to approximately 180 minutes.

The liquid used to form the first region Rl includes the first material, a component formulated as necessary (for example, ink), and water (a dispersion medium). The formation of the first region Rl may be performed, for example, by spray coating, roll coating, film transfer and curtain coating. To ensure that no liquid is applied to the second region R2, a masking tape or the like may be used to pre-mask a region corresponding to the second region R2.

The amount of application per unit area (solid mass) in the first region Rl may be, for example, approximately 1 to approximately 50 g/m², or approximately 2 to approximately 40 g/m², or approximately 5 to approximately 30 g/m². Moisture may be volatilized by performing the drying step after application. For example, the main body portion 1 to which the liquid is applied to form a pattern may be dried for approximately 10 to approximately 180 minutes in a hot air drier set to approximately 80 to approximately 250°C. As a result, the first region Rl is formed on the surface of the main body portion 1.

The step of forming the first region Rl may be performed in multiple steps. Namely, a method of forming the first region Rl may include the steps of applying a liquid containing the first material to the entire surface of the main body portion 1, masking a region corresponding to the second region R2, and applying a liquid containing the first material to a region corresponding to the first region Rl in this order. Alternatively, the method of forming the first region Rl may include the steps of masking a region corresponding to the second region R2, applying a liquid containing the first material to a region corresponding to the first region Rl, removing the mask covering the region corresponding to the second region R2, and applying a liquid containing the first material to the entire surface of the main body portion 1 in this order.

The holding material 10 is used to hold the pollution control element 30 within a pollution control apparatus 50 as illustrated in FIG. 3. Specific examples of the pollution control element 30 include a catalyst support, and a filter element for purifying exhaust gas from an engine. Specific examples of the pollution control apparatus 50 include a catalytic converter and an exhaust cleaning device (for example, a diesel particulate filter device).

The pollution control apparatus 50 illustrated in FIG. 3 includes the casing 20, the pollution control element 30 disposed within the casing 20, and the holding material 10 disposed between an inside surface of the casing 20 and an outer surface of the pollution control element 30. The pollution control apparatus 50 further includes a gas inflow port 21 configured to introduce exhaust gas into the pollution control element 30, and a gas flow outlet 22 configured to discharge exhaust gas that has passed through the pollution control element 30.

In the pollution control apparatus 50, the holding material 10 is disposed in a state interposed between the inside surface of the casing 20 and the outer surface of the pollution control element 30. In the present embodiment, the surface Fl on which the first region Rl is formed faces the inside surface of the casing 20. The width of a gap between the inside surface of the casing 20 and the outer surface of the pollution control element 30 is preferably approximately 1.5 to approximately 15 mm from the perspective of ensuring hermeticity and reducing the usage of the holding material 10. A method of compressing and assembling the holding material 10 includes a clamshell method, a stuffing method, a tourniquet method, and the like.

A catalyst to be supported on a catalyst support is typically a metal (for example, platinum, ruthenium, osmium, rhodium, iridium, nickel, palladium, and the like) and metal oxides (for example, vanadium pentoxide, titanium dioxide, and the like), and is preferably used in the form of a coating. Note that the pollution control apparatus can be constructed as a diesel particulate filter or a gasoline particulate filter by applying the filter element in place of the catalyst support.

Detailed descriptions have been given above for the preferred embodiments of the present invention. However, the present invention is not limited to the embodiments described above. For example, in the embodiment described above, there is exemplified the aspect in which the surface Fl on which the first region Rl is formed faces the inside surface of the casing 20 (see FIG. 3), but the surface Fl may face an outer circumferential surface of the pollution control element 30.

In the embodiment described above, there is exemplified the aspect in which the first region Rl is formed only on the surface Fl of the main body portion 1, but the first region Rl may be formed on both surfaces (the surface F 1 and a surface F2) of the main body portion 1.

Furthermore, in FIG. 1 and FIG. 2, there is illustrated the aspect in which the first region Rl is formed to sink into the main body portion 1, but the first region Rl may be formed to be layered on the surface of the main body portion 1.

In the embodiment described above, the aspect in which the first region Rl has a striped pattern is exemplified, but the aspect of the first region Rl is not limited to this aspect. For example, as illustrated in FIG. 4A, the first region Rl may be formed in a lattice-like pattern. As illustrated in FIGS. 4B and 4C, the first region Rl may be formed in a dotted pattern. When the first region Rl is dot-shaped, the area proportion of the first region Rl may be, for example, 10 to 90%, and may be 15 to 80% or 20 to 70%, based on the area of the surface Fl . Note that the aspects illustrated in FIGS. 4B and 4C can also be referred to as the second region R2 being formed in a lattice pattern. The width and pitch of the stripes or lattices may be set appropriately according to the size of the holding material or flexibility required for the holding material. The holding materials 10A, 10B, 10C illustrated in FIGS. 4A to 4C include a part P in which the first region Rl and the second region R2 are interleaved with each other along the winding direction of the main body portion 1.

Further, the pattern of the first region Rl may be in an aspect as illustrated in FIGS. 5 A to 5C. In FIG. 5A, the first region Rl of a holding material 10D is formed in a wave-like pattern. The first region Rl of a holding material 10E illustrated in FIG. 5B includes a combination of a wave like pattern and a pattern of stripes extending in the winding direction. The first region Rl includes a wave shape having an amplitude in the winding direction, and thus holding force can be further improved. When the first region Rl includes a wave-like pattern, the area proportion of the first region Rl may be, for example, 10 to 90%, and may be 15 to 80% or 20 to 70%, based on the area of the surface Fl . The first region Rl of a holding material 10F is formed by a letter in FIG. 5C. The first region Rl may be formed by a marking such as a logo (not illustrated), or a combination of a letter and a marking. When the first region Rl includes a letter and/or a marking, the area proportion of the first region Rl may be, for example, 10 to 90%, and may be 15 to 80% or 20 to 70%, based on the area of the surface Fl .

EXAMPLES

The present disclosure will be described with reference to examples of the present disclosure. Note that the present invention is not limited by these examples.

Example 1

Production of main body portion

2.5 L water was placed in a stainless steel vessel of volume 10 L and stirred with a fin blade. The following raw materials were charged at 1 minute intervals to the water being stirred.

(1) Aluminum sulfate (solid content concentration 40% aqueous solution, manufactured by Nippon Light Metal Co., Ltd.): 6 g (2) Organic binder (acrylic latex, Nipol LX874 (trade name), manufactured by Zeon Corporation): 2.6 g

(3) Colloidal silica (Snowtex O (trade name), manufactured by Nissan Chemical

Corporation): 10 g

(4) Sodium liquid aluminate (solid content 40%, Asada Chemical Industry Co., Ltd.): 3.5 g

After all the raw materials were charged, agglomerated particles were confirmed in the solution. As the next step, a needle-punched alumina fiber blanket (manufactured by Mitsubishi Chemical Corporation, MAFTEC MLS-2 blanket (trade name)) was cut into 15 cm ^c 40 cm. The blanket was then placed over a metal mesh, and after the solution was poured from above, the blanket was suctioned and dehydrated for 15 seconds over the metal mesh. After the blanket was impregnated with the above-described solution in this manner, the blanket was dried for 45 minutes in a hot air drier set to a temperature of l70°C. The main body portion of the holding material was produced as a result.

Formation of First Region

A liquid for forming the first region was prepared as follows. First, alumina sol AS520 (manufactured by Nissan Chemical Corporation) was prepared as a first material. A liquid was prepared by diluting the alumina sol AS520 with water such that the solid content concentration was 5%. Red ink (WMBE-5, manufactured by Orient Chemical Industries Co., Ltd.) was added to the liquid, and a coating liquid was made visible. The mixture was stirred for one minute.

A masking tape having a width of 6 mm was applied to one surface of a main body portion (a surface on the side that is in contact with an inner surface of a casing) by the width of 150 mm along a direction orthogonal to the winding direction of the main body portion. A next masking tape was applied in the same manner at the interval of 2.5 mm in the winding direction from the region where the masking tape was applied. This operation was repeated to cover a region to be the second region with the masking tape.

A spray air gun was used to spray a predetermined amount of the mixture liquid on one side of the main body portion. After the masking tape was peeled off, drying was performed for 10 minutes by a hot air dryer set to a temperature of l70°C. A holding material including a first region formed in a striped shape was obtained as a result. The area proportion of the first region was 30%, based on the overall area of one surface of the main body portion. Furthermore, the amount of the first material (alumina) per unit area of the first region was 20 g/m².

Example 2

A holding material was prepared in the same manner as in Example 1 with the exception that a masking tape was applied as follows. That is, a masking tape having a width of 4 mm was applied to one surface of a main body portion (a surface on the side that is in contact with an inner surface of a casing) by the width 150 mm along a direction orthogonal to the winding direction of the main body portion. A next masking tape was applied in the same manner at an interval of 4 mm in the winding direction from the region where the masking tape was applied. This operation was repeated to cover a region to be a second region with the masking tape. The area proportion of a first region was 50%, based on the overall area of one surface of the main body portion.

Example 3

A holding material was prepared in the same manner as in Example 1 with the exception that a masking tape was applied as follows. That is, a masking tape having a width of 2 mm was applied to one surface of a main body portion (a surface on the side that is in contact with an inner surface of a casing) by the width of 150 mm along a direction orthogonal to the winding direction of the main body portion. A next masking tape was applied in the same manner at an interval of 6 mm in the winding direction from the region where the masking tape was applied. This operation was repeated to cover a region to be a second region with the masking tape. The area proportion of a first region was 75%, based on the overall area of one surface of the main body portion.

Example 4

A holding material was prepared in the same manner as in Example 1 with the exception that a masking tape was applied as follows. That is, a region to be a second region was covered with a masking tape such that a first region formed a lattice-like pattern. The area proportion of the first region was 75%, based on the overall area of one surface of a main body portion.

Example 5

A holding material was prepared in the same manner as in Example 1 with the exception that a masking tape was applied as follows. That is, a region to be a second region was covered with a masking tape such that the first region formed a dotted pattern. The area proportion of a first region was 30%, based on the overall area of one surface of a main body portion.

Comparative Example 1

A main body portion prepared in the same manner as in Example 1 was used as a holding material according to Comparative Example 1. That is, in the holding material according to Comparative Example 1, a first region was not formed (the area proportion of the first region: 0%).

Comparative Example 2

A holding material was prepared in the same manner as in Example 1 with the exception that no masking tape was applied to one surface of a main body portion (a surface on the side that is in contact with an inner surface of a casing). That is, the holding material according to

Comparative Example 2 included a first region formed across all of the one surface of the main body portion (the area proportion of the first region: 100%).

Measurement of Coefficient of Static Friction of Holding Material

A coefficient of static friction of the holding material was measured by the following procedure by using an Autograph AGS100D (registered trademark, manufactured by Shimadzu Corporation). Namely, each of the holding materials according to the examples and the comparative examples was cut into a 50 mm square to prepare a test specimen. As illustrated in FIG. 6, a test specimen 11 was secured by bonding a surface of the test specimen 11 opposite a surface 12 to be measured for the coefficient of static friction to a stainless steel plate 66 via a double -sided adhesive tape 62.

One end of a stainless steel cord 63 of approximately 1 m was secured to the stainless steel plate 66 and the other end was secured to a load cell 64 via a pulley block 65. At this time, the pulley block 65 was placed exactly beneath the load cell 64 to move the plate 66 secured to the test specimen 11 parallel to the ground when the load cell 64 was lifted.

Next, the test specimen 11 was placed on a plate 61 in a position which is parallel to the ground and at which the cord 63 is perpendicular to the central axis of the pulley block 65. A stainless steel plate was used as the plate 61 in place of the casing, and specifically, the plate was machine processed for a plate surface 2B treatment (cold rolling) to have a surface roughness Ra of 0.2 to 0.5 pm. The height of the load cell 64 was adjusted such that the test specimen 11 was at a position of the maximum distance from the pulley block 65.

A load 67 of 12 kg was placed on a plate 66. Subsequently, the load cell 64 was lifted and the cord 63 was pulled in the arrow direction at a 100 mm/minute traction. The load measured immediately before the test specimen 11 starts slipping from the surface of the plate 61 was recorded as static friction force (N). The coefficient of static friction was calculated by dividing the static friction force by the load (N) applied to the test specimen 11 including the plate 66. The results are shown in Table 1.

Evaluation of Windability

Each of the holding materials according to the examples and the comparative examples was cut into a width of 70 mm and a length of 350 mm, and was wound around an outer circumference of a catalyst support having a cylindrical shape of a length 115 mm and an outer diameter 105 mm (trade name“HONEY CERAM”, manufactured by NGK Insulators, Ltd.). A maximum gap between the pollution control element and the holding material was measured by using JIS1 grade linear scale. A holding material having a small maximum gap value can be evaluated as being more easily wound than a holding material having a large value. The results are shown in Table 1.

Table 1

Industrial Applicability

According to the present disclosure, a holding material is provided including a surface that is easy to be wound around an outer peripheral surface of a pollution control element at the manufacturing step of a pollution control apparatus and that can improve holding force.

Claims

1. A holding material wound on an outer peripheral surface of a pollution control element, the holding material comprising:

a main body portion having a sheet-like shape and including at least a first inorganic fiber; a first region provided on at least one surface of the main body portion and where a first material including at least an inorganic material is attached to the first inorganic fiber; and

a part in which, along a winding direction of the main body portion, the first region and a second region are interleaved with each other, and the first material is not attached to the second region or is attached to the second region with fewer attachment amount than to the first region.

2. The holding material according to claim 1, wherein the first region is formed to make a regular pattern on the surface.

3. The holding material according to claim 1 or 2, wherein the second region is continuously formed from one end to the other end in a width direction of the main body portion.

4. The holding material according to any one of claims 1 to 3, wherein the first region is continuously formed from one end to the other end in a width direction of the main body portion.

5. The holding material according to any one of claims 1 to 4, wherein the first region is formed to make a striped pattern.

6. The holding material according to any one of claims 1 to 3, wherein the second region is formed to make a lattice-like pattern.

7. The holding material according to any one of claims 1, 2 and 4, wherein the first region is formed to make a lattice-like pattern.

8. The holding material according to any one of claims 1 to 7, wherein the first region contains a material that emits light upon irradiation with black light.

9. The holding material according to any one of claims 1 to 8, wherein the first region is formed by a letter and/or a marking.

10. The holding material according to any one of claims 1 to 9, wherein the first region has a different color from the second region.

11. The holding material according to any one of claims 1 to 10, wherein the first material comprises a second inorganic fiber having a different aspect ratio from the first inorganic fiber.

12. The holding material according to any one of claims 1 to 11, wherein the first material comprises an inorganic particle.

13. The holding material according to any one of claims 1 to 12, wherein the first material comprises an inorganic adhesive.

14. The holding material according to any one of claims 1 to 13, wherein the first material comprises an organic binder.

15. A pollution control apparatus comprising :

a casing;

a pollution control element disposed within the casing; and

the holding material according to any one of claims 1 to 14 disposed between the casing and the pollution control element.

16. The pollution control apparatus according to claim 15, wherein the holding material at least includes the first region on a surface that is in contact with an inner surface of the casing.

17. The pollution control apparatus according to claim 15, wherein the holding material at least includes the first region on a surface that is in contact with an outer peripheral surface of the pollution control element.

18. A method of manufacturing the holding material according to any one of claims 1 to 14, the method comprising the steps of:

preparing the main body portion; and

providing the first region on at least one surface of the main body portion.