Hole plugging slurry of wall flow type honeycomb ceramic filter body and preparation method of hole plugging slurry

Abstract

The invention relates to hole plugging slurry of a wall flow type honeycomb ceramic filter body and a preparation method of the hole plugging slurry. The hole plugging slurry comprises inorganic powder and an additive, the additives comprise the following components in percentage by mass of the inorganic powder: 0.1-1% of an organic binder, 0.3-1% of an anti-sagging agent, 0.05-0.2% of a flatting agent and 0.3-2% of a water reducing agent. The hole plugging slurry provided by the invention has good tiling property and slurry hanging property, so that the scraped or pressed hole plugging slurry is quickly tiled to the hole wall surface when entering the honeycomb ceramic hole channel, the hole wall is completely and compactly filled with the slurry in the process of advancing in the hole, the bonding strength between the slurry and the hole wall is improved, and the hole plugging quality is improved. And the problem of peeling or local light leakage in the drying or sintering process is avoided.

Description

Technical Field

[0001] The invention relates to the technical field of honeycomb ceramic pore plugging materials, and in particular to a pore plugging slurry for a wall-flow type honeycomb ceramic filter and a preparation method thereof. Background Art

[0002] With the continuous deepening and strictness of environmental protection regulations in all walks of life, the market demand for wall-flow honeycomb ceramic filters has increased, especially in the fields of diesel engine particulate filters (DPF), gasoline engine particulate filters (GPF), industrial high-temperature smoke filtration, etc., which have become the key core components of exhaust gas after-treatment devices. Due to the staggered plugging structure of the wall-flow honeycomb ceramic filter, the product cannot be formed in one go, and the straight-through structure of the to-be-fired blank or the semi-finished product after firing needs to be staggered to form the final wall-flow structure.

[0003] At present, the industry generally adopts the method of laser drilling + printing plugging to stagger the plugging of straight-through honeycomb ceramic carriers, so as to produce wall-flow honeycomb ceramic filter bodies. When laser drilling is performed on the transparent tape attached to the surface of the straight-through carrier, in order to avoid the holes on the tape penetrating two adjacent grids, the opening size of the corresponding grid channel is usually set smaller than the inscribed circle diameter or side length of the honeycomb ceramic channel. When the plugging slurry is scraped or pressed into the honeycomb ceramic channel through the holes formed by laser drilling on the tape, it is necessary to make it tightly combined with the honeycomb ceramic channel wall to ensure that there is no light leakage at the plugging position of the finished product, and to avoid smoke leakage during the use of the product, thereby ensuring that the filtration and purification system meets the emission standards.

[0004] In the actual production process, in order to ensure that the plugging reaches a sufficient depth, the fluidity of the plugging slurry needs to be adjusted to an optimal state. However, when the slurry with good fluidity enters the pores of the honeycomb ceramic carrier through the holes punched by the laser on the tape, it often does not diffuse to the surroundings, or the diffusion effect is poor, resulting in a loose bond between the plugging slurry and the honeycomb ceramic pores, especially at right-angle walls, where the plugging slurry often cannot reach. In this case, after drying or firing, the plugging slurry will be partially or completely separated from the pore wall of the honeycomb ceramic, causing the plugging to fall off or local light leakage.

[0005] Therefore, it is necessary to provide a plugging slurry for wall-flow honeycomb ceramic filter, so that when it is scraped or pressed into the honeycomb ceramic pores, it can be quickly spread on the pore wall surface, so that the pore wall is fully filled with the slurry, thereby avoiding the problem of plugging falling off or local light leakage. Summary of the invention

[0006] In view of the above problems, the object of the present invention is to provide a plugging slurry for a wall-flow honeycomb ceramic filter body and a preparation method thereof. Compared with the prior art, the plugging slurry provided by the present invention can densely fill the pore walls of the honeycomb ceramic, improve the bonding force between the slurry and the pore walls, and avoid the problems of plugging hole shedding or local light leakage after drying or firing.

[0007] To achieve the object of the present invention, the following technical solutions are adopted:

[0008] In the first aspect, the present invention provides a plugging slurry for a wall-flow honeycomb ceramic filter body, and the plugging slurry includes inorganic powder and additives;

[0009] Calculated by mass percentage of the inorganic powder, the additives include: 0.1-1% of an organic binder, 0.3-1% of an anti-sagging agent, 0.05-0.2% of a leveling agent, and 0.3-2% of a water reducing agent.

[0010] In the plugging slurry provided by the present invention, by adding an organic binder, an anti-sagging agent, a leveling agent and a water reducing agent to the inorganic powder and adjusting their mass ratios, the spreading property and slurry hanging property of the plugging slurry can be adjusted, so that when the scraped or pressed plugging slurry enters the honeycomb ceramic pore channels, it can quickly spread to the pore wall surface. At the same time, the spread slurry will not flow in the pore channels or form a conical tip phenomenon without the extrusion of subsequent new slurry. Since the slurry is pushed forward by an external force in the pore walls, the slurry will densely fill the pore walls it passes through, and the slurry and the pore walls will be more firmly bonded due to the external force, and there will be no problems of peeling or local light leakage during drying or firing.

[0011] The organic binder is 0.1-1%, for example, it can be 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9% or 1%, but not limited to the listed values, and other unlisted values within the numerical range are equally applicable; the anti-sagging agent is 0.3-1%, for example, it can be 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9% or 1%, but not limited to the listed values, and other unlisted values within the numerical range are equally applicable; the leveling agent is 0.05-0.2%, for example, it can be 0.05%, 0.06%, 0.08%, 0.1%, 0.12%, 0.14%, 0.16%, 0.18% or 0.2%, but not limited to the listed values, and other unlisted values within the numerical range are equally applicable; the water reducing agent is 0.3-2%, for example, it can be 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.2%, 1.4%, 1.6%, 1.8% or 2%, but not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0012] Preferably, the hole plugging slurry includes green body hole plugging slurry or fired body hole plugging slurry.

[0013] In the present invention, according to the different usage stages of the hole plugging slurry, the hole plugging slurry can be further divided into green body hole plugging slurry or fired body hole plugging slurry. The green body refers to the formed but unsintered body. The composition of the inorganic powder generally needs to match the green body to avoid defects or performance degradation during subsequent sintering and ensure that the shrinkage rates are basically the same. The fired body refers to the body after sintering or other heat treatments. In the hole plugging of the fired body, the slurry forms a uniform coating on the surface of the fired body, and the composition of the inorganic powder needs to match the fired body to ensure the requirements for high temperature resistance and other properties during use.

[0014] Preferably, the inorganic powder of the green body hole plugging slurry includes the inorganic formulation material of the green body itself.

[0015] In the present invention, the inorganic formulation material of the green body itself is not particularly limited and can be selected according to actual production needs. The hole plugging slurry provided by the present invention is also applicable.

[0016] Preferably, the additive in the green body hole plugging slurry further includes a solvent.

[0017] Preferably, the solvent includes water.

[0018] Preferably, calculated by mass percentage of the inorganic powder, the solvent accounts for 35 - 50%, for example, it can be 35%, 36%, 38%, 40%, 42%, 44%, 46%, 48% or 50%, but is not limited to the listed values. Other unlisted values within the numerical range are equally applicable.

[0019] Preferably, in the green body hole plugging slurry, calculated by mass percentage of the inorganic powder, the additive includes: organic binder 0.1 - 0.5%, anti - sagging agent 0.3 - 1%, leveling agent 0.05 - 0.2%, water - reducing agent 0.3 - 2%, and water 35 - 50%.

[0020] Preferably, the inorganic powder of the fired body hole plugging slurry includes powder of the same material as the honeycomb ceramic filter, washed kaolin, and calcined alumina powder.

[0021] In the present invention, the washed kaolin and calcined alumina powder are common raw materials in the art and can be obtained by purchase.

[0022] Preferably, the powder of the same material as the honeycomb ceramic filter includes any one of cordierite, silicon carbide, or mullite.

[0023] Preferably, in terms of mass percentage, the inorganic powder includes: 90-95% of the powder of the same material as the honeycomb ceramic filter, such as 90%, 91%, 92%, 93%, 94% or 95%, but not limited to the listed values, and other unlisted values within the numerical range are equally applicable; 1-5% of washed kaolin, such as 1%, 2%, 3%, 4% or 5%, but not limited to the listed values, and other unlisted values within the numerical range are equally applicable; 1-5% of calcined alumina powder, such as 1%, 2%, 3%, 4% or 5%, but not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0024] Preferably, the additive in the green body hole plugging slurry further includes an inorganic binder.

[0025] Preferably, the inorganic binder includes silica sol.

[0026] Preferably, the mass percentage of silicon dioxide in the silica sol is 30-40%, for example, any one or at least two combinations of the commonly used silica sols on the market with a mass percentage of 30%, 35% or 40% can be adopted.

[0027] Preferably, in terms of mass percentage of the inorganic powder, the silica sol accounts for 35-50%, such as 35%, 36%, 38%, 40%, 42%, 44%, 46%, 48% or 50%, but not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0028] Preferably, in the green body hole plugging slurry, in terms of mass percentage of the inorganic powder, the additives include: 0.3-1% of an organic binder, 0.3-1% of an anti-sagging agent, 0.05-0.2% of a leveling agent, 0.3-2% of a water reducing agent, and 35-50% of silica sol.

[0029] Preferably, the organic binder includes any one or at least two combinations of hydroxypropyl methylcellulose, hydroxyethyl cellulose, methylcellulose, water-soluble polyvinyl alcohol or modified starch.

[0030] In the present invention, by specifically selecting the above organic binder, the slurry can be thickened, preventing the inorganic raw materials from settling or stratifying, thereby ensuring the uniformity and stability of the slurry.

[0031] Preferably, the anti-sagging agent includes polyethylene foamed balls and / or acrylic water-absorbing resin.

[0032] Preferably, the D50 particle size of the polyethylene foamed balls is 15-25 μm, such as 15 μm, 20 μm or 25 μm, but not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0033] In the present invention, by specifically selecting the above-mentioned anti-sagging agent, it is possible to prevent the slurry from dripping rapidly like water droplets under the action of its own gravity, thereby effectively avoiding the occurrence of sagging phenomenon.

[0034] Preferably, the leveling agent includes polyethylene oxide.

[0035] In the present invention, by specifically selecting the above-mentioned leveling agent, the internal lubricity of the slurry can be improved, and the viscosity of the slurry can be reduced, so that the slurry can be scraped into the product pores more smoothly, ensuring the efficiency and uniformity of the hole filling process.

[0036] Preferably, the water reducing agent includes any one or a combination of at least two of polyether polyol, glycerol or white oil. The polyether polyol is a commonly used raw material in the art. For example, PPG8000 produced by Hai'an Petrochemical can be used.

[0037] In the present invention, by specifically selecting the above-mentioned water reducing agent, the dispersion effect on inorganic powder and organic binder can be improved, and further, the usage amount of water or silica sol can be significantly reduced.

[0038] In a second aspect, the present invention provides a method for preparing a plugging slurry for a wall-flow honeycomb ceramic filter body as described in the first aspect of the present invention. The preparation method includes:

[0039] Mixing the inorganic powder and the additive in sequence, detecting the viscosity, and storing and aging to obtain the plugging slurry.

[0040] In the preparation method provided by the present invention, through mixing and viscosity detection, it is ensured that the components of the plugging slurry are uniform and have appropriate fluidity. During the storage and aging process, the performance of the slurry will be further stabilized, enabling it to better fill the pores, thereby improving the compactness and uniformity of plugging the holes.

[0041] Preferably, the preparation method specifically includes the following steps:

[0042] (1) Pour water or silica sol into a blender, then add the remaining liquid additives for the first stirring, then add the inorganic powder and the remaining solid additives for the second stirring, then stop the machine and manually turn the bottom of the stirring barrel, and then conduct the third stirring to obtain the slurry;

[0043] (2) Detect the viscosity of the slurry obtained in step (1). If the viscosity meets the requirements, store and age the slurry. If the viscosity does not meet the requirements, add water or silica sol to adjust to the required viscosity, and then store and age.

[0044] In the present invention, when adding the solid additives, they are generally added according to the mass percentage ratio. Those with a larger proportion are added first, and those with a smaller proportion are added later.

[0045] Preferably, the rotation speed of the first stirring is 80 - 82 rpm. For example, it can be 80 rpm, 81 rpm, or 82 rpm, but is not limited to the listed values. Other unlisted values within the numerical range are equally applicable.

[0046] Preferably, the time of the first stirring is 10 - 30 min. For example, it can be 10 min, 12 min, 14 min, 15 min, 16 min, 18 min, 20 min, 22 min, 25 min, 26 min, 28 min, or 30 min, but is not limited to the listed values. Other unlisted values within the numerical range are equally applicable.

[0047] Preferably, the rotation speed of the second stirring is 132 - 168 rpm. For example, it can be 132 rpm, 140 rpm, 145 rpm, 150 rpm, 155 rpm, 160 rpm, or 168 rpm, but is not limited to the listed values. Other unlisted values within the numerical range are equally applicable.

[0048] Preferably, the time of the second stirring is 20 - 40 min. For example, it can be 20 min, 25 min, 30 min, 35 min, or 40 min, but is not limited to the listed values. Other unlisted values within the numerical range are equally applicable.

[0049] Preferably, the rotation speed of the third stirring is 288 - 292 rpm. For example, it can be 288 rpm, 289 rpm, 290 rpm, 291 rpm, or 292 rpm, but is not limited to the listed values. Other unlisted values within the numerical range are equally applicable.

[0050] Preferably, the time of the third stirring is 10 - 30 min. For example, it can be 10 min, 12 min, 14 min, 15 min, 16 min, 18 min, 20 min, 22 min, 25 min, 26 min, 28 min, or 30 min, but is not limited to the listed values. Other unlisted values within the numerical range are equally applicable.

[0051] Preferably, the required viscosity is 8000 - 15000 mPa·s. For example, it can be 8000 mPa·s, 9000 mPa·s, 10000 mPa·s, 11000 mPa·s, 12000 mPa·s, 13000 mPa·s, 14000 mPa·s, or 15000 mPa·s, but is not limited to the listed values. Other unlisted values within the numerical range are equally applicable.

[0052] Preferably, the aging time is > 12 h, for example, it can be 13 h, 14 h or 15 h, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0053] In the present invention, before use, the plugging slurry generally needs to be stirred at a rotation speed of 80 - 82 rpm for 5 - 10 min, for example, it can be 2 min, 5 min, 8 min or 10 min, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0054] As a preferred technical solution of the second aspect of the present invention, the preparation method includes the following steps:

[0055] (1) Pour water or silica sol into a blender, then add the remaining liquid additives and conduct the first stirring at a rotation speed of 80 - 82 rpm for 10 - 30 min. After that, add the inorganic powder and the remaining solid additives and conduct the second stirring at a rotation speed of 132 - 168 rpm for 20 - 40 min. Then stop the machine and manually turn the bottom of the stirring barrel, and then conduct the third stirring at a rotation speed of 288 - 292 rpm for 10 - 30 min to obtain the slurry;

[0056] (2) Conduct a viscosity test on the slurry obtained in step (1). If the viscosity reaches 8000 - 15000 mPa·s, then store and age the slurry for > 12 h. If the viscosity does not meet the requirements, add water or silica sol to adjust to the required viscosity, and then conduct storage and aging. Before use, the plugging slurry generally needs to be stirred at a rotation speed of 80 - 82 rpm for 5 - 10 min.

[0057] Compared with the prior art, the present invention has the following beneficial effects:

[0058] (1) In the plugging slurry provided by the present invention, according to different stages of plugging, it is further divided into green body plugging slurry or fired body plugging slurry. By controlling the addition of additives such as organic binders, anti - sagging agents, leveling agents and water - reducing agents, the spreading property and slurry hanging property of the plugging slurry can be adjusted, so that when the scraped or pressed plugging slurry enters the honeycomb ceramic pore channels, it can quickly spread to the pore wall surface. At the same time, the spread slurry will not flow in the pore channels or form a conical top phenomenon without the extrusion of subsequent new slurry. The slurry completely and densely fills the pore wall during the process of passing through the pores, improving the bonding strength between the slurry and the pore wall, and avoiding problems such as peeling or local light leakage during the drying or firing process.

[0059] (2) The method for preparing the hole-blocking slurry provided by the present invention ensures the uniform composition and appropriate fluidity of the hole-blocking slurry through mixing and viscosity detection. During the storage and aging process, the performance of the slurry will be further stabilized, enabling it to better fill the pores, thereby improving the densification and uniformity of hole blocking.

[0060] (3) The hole-blocking slurry provided by the present invention has a strong bond with the hole wall. Under optimal conditions, when a customized needle gauge is used for pressure testing, the breaking strength of the hole-blocking material reaches above 10.7 MPa, and there will be no light leakage problem. Specific embodiments

[0061] The technical solution of the present invention will be further described below through specific embodiments. Those skilled in the art should understand that the embodiments are only for helping to understand the present invention and should not be regarded as specific limitations to the present invention.

[0062] Example 1

[0063] This example provides a hole-blocking slurry for a wall-flow honeycomb ceramic filter body. The hole-blocking slurry is a green body hole-blocking slurry, including inorganic powder and additives;

[0064] The inorganic powder is the inorganic formula material for the green body. Calculated by mass percentage, it includes 39.5% talc, 15% washed kaolin, 20% calcined kaolin, 18% alumina, and 7.5% silica.

[0065] The additives are calculated by mass percentage of the inorganic powder as follows:

[0066] Organic binder, hydroxypropyl methylcellulose, 0.2%, HPMC 65HD15000 produced by Shandong Hedda;

[0067] Anti-sagging agent, polyethylene foam balls, 0.6%, Borikem 180DU20 from the United States, particle size 25 μm;

[0068] Leveling agent, polyethylene oxide, 0.1%, Sumitomo A08 from Japan;

[0069] Water reducing agent, polyether polyol, 1%, PPG8000 from Hai'an Petrochemical;

[0070] Solvent, deionized water, 40%.

[0071] This example also provides a method for preparing the above hole-blocking slurry. The preparation method includes the following steps:

[0072] (1) Pour deionized water into a blender, then add the remaining liquid additive, i.e., polyether polyol, and conduct the first stirring for 20 min at a rotation speed of 82 rpm. After that, add the inorganic powder and the remaining solid additives, i.e., hydroxypropyl methylcellulose, polyethylene foamed balls, and polyethylene oxide, and conduct the second stirring for 30 min at a rotation speed of 140 rpm. Then stop the machine and manually turn the bottom of the stirring barrel, and then conduct the third stirring for 20 min at a rotation speed of 290 rpm to obtain the slurry;

[0073] (2) Conduct viscosity detection on the slurry obtained in step (1). If the viscosity reaches 12000 mPa·s, store and age the slurry for 24 h. If the viscosity does not meet the requirements, add water or silica sol to adjust to the required viscosity, and then store and age it. Generally, the hole-blocking slurry also needs to be stirred for 5 min at a rotation speed of 82 rpm before use.

[0074] Example 2

[0075] This example provides a hole-blocking slurry for a wall-flow honeycomb ceramic filter body. The hole-blocking slurry is a green body hole-blocking slurry, which includes inorganic powder and additives;

[0076] The inorganic powder is the inorganic formula material for the green body. Calculated by mass percentage, it includes 39.5% talc, 15% washed kaolin, 20% calcined kaolin, 18% alumina, and 7.5% silica.

[0077] The additives are calculated by mass percentage of the inorganic powder as follows:

[0078] Organic binder, hydroxypropyl methylcellulose, 0.1%, HPMC 65HD15000 produced by Shandong Hedda;

[0079] Anti-sagging agent, polyethylene foamed balls, 1%, Borikem 180DU20 from the United States, particle size 25 μm;

[0080] Leveling agent, polyethylene oxide, 0.05%, Sumitomo A08 from Japan;

[0081] Water reducing agent, white oil, 2%;

[0082] Solvent, deionized water, 35%.

[0083] This example also provides a preparation method for the above hole-blocking slurry. The preparation method includes the following steps:

[0084] (1) Pour deionized water into a blender, then add the remaining liquid additive, i.e., white oil, and conduct the first stirring for 15 min at a rotational speed of 80 rpm. After that, add the inorganic powder and the remaining solid additives, i.e., hydroxypropyl methylcellulose, polyethylene foam balls, and polyethylene oxide, and conduct the second stirring for 20 min at a rotational speed of 132 rpm. Then stop the machine and manually turn the bottom of the stirring barrel, and then conduct the third stirring for 30 min at a rotational speed of 290 rpm to obtain a slurry.

[0085] (2) Conduct a viscosity test on the slurry obtained in step (1). If the viscosity reaches 10,000 mPa·s, store and age the slurry for 24 h. If the viscosity does not meet the requirements, add water or silica sol to adjust it to the required viscosity, and then store and age it. Generally, the plugging slurry also needs to be stirred for 8 min at a rotational speed of 80 rpm before use.

[0086] Example 3

[0087] This example provides a plugging slurry for a wall-flow honeycomb ceramic filter body. The plugging slurry is a green body plugging slurry, which includes an inorganic powder and additives.

[0088] The inorganic powder is an inorganic formula material for the green body. By mass percentage, it includes 39.5% talc, 15% washed kaolin, 20% calcined kaolin, 18% alumina, and 7.5% silica.

[0089] The additives are as follows by mass percentage of the inorganic powder:

[0090] Organic binder, hydroxyethyl cellulose, 0.5%, Silver Eagle HEC30;

[0091] Anti-sagging agent, acrylic water-absorbing resin, 0.3%, manufacturer: Fuhe New Materials, 1000 mesh;

[0092] Leveling agent, polyethylene oxide, 0.2%, Sumitomo A08 of Japan;

[0093] Water reducing agent, glycerol, 0.3%;

[0094] Solvent, deionized water, 50%.

[0095] This example also provides a preparation method for the above plugging slurry. The preparation method includes the following steps:

[0096] (1) Pour deionized water into a blender, then add the remaining liquid additive, i.e., glycerol, and conduct the first stirring for 30 min at a rotational speed of 82 rpm. After that, add the inorganic powder and the remaining solid additives, i.e., hydroxyethyl cellulose, acrylic acid water-absorbing resin, and polyethylene oxide, and conduct the second stirring for 40 min at a rotational speed of 160 rpm. Then stop the machine and manually turn the bottom of the stirring barrel, and then conduct the third stirring for 10 min at a rotational speed of 290 rpm to obtain a slurry.

[0097] (2) Conduct a viscosity test on the slurry obtained in step (1). If the viscosity reaches 14,000 mPa·s, store and age the slurry for 24 h. If the viscosity does not meet the requirements, add water or silica sol to adjust it to the required viscosity, and then store and age it. Generally, the plugging slurry also needs to be stirred for 10 min at a rotational speed of 82 rpm before use.

[0098] Example 4

[0099] This example provides a plugging slurry for a wall-flow honeycomb ceramic filter body. The plugging slurry is a plugging slurry for a green body, comprising an inorganic powder and additives.

[0100] The inorganic powder comprises: 93% of the powder of the same material as the 325-mesh honeycomb ceramic filter body, 3% of 1000-mesh washed kaolin (IMERYS Glomax LL), and 4% of 1250-mesh calcined alumina powder (Zhengzhou Research Institute of Chalco AC-202GR).

[0101] The additives, calculated by mass percentage of the inorganic powder, are specifically as follows:

[0102] Organic binder, hydroxypropyl methyl cellulose, 0.3%, HPMC 65HD15000 produced by Shandong Hedda;

[0103] Anti-sagging agent, polyethylene foamed beads, 0.6%, Borikem 180DU20 from the United States, particle size 25 μm;

[0104] Leveling agent, polyethylene oxide, 0.1%, Sumitomo A08 from Japan;

[0105] Water-reducing agent, polyether polyol, 1%, PPG8000 from Hai'an Petrochemical;

[0106] Silica sol, 45%, mass percentage of silicon dioxide 30%.

[0107] This example also provides a preparation method for the above plugging slurry. The preparation method comprises the following steps:

[0108] (1) Pour the silica sol into a blender, then add the remaining liquid additive, i.e., polyether polyol, and conduct the first stirring for 20 min at a rotational speed of 82 rpm. After that, add the inorganic powder and the remaining solid additives, i.e., hydroxypropyl methylcellulose, polyethylene foamed balls, and polyethylene oxide, and conduct the second stirring for 30 min at a rotational speed of 140 rpm. Then stop the machine and manually turn the bottom of the stirring barrel, and then conduct the third stirring for 20 min at a rotational speed of 290 rpm to obtain a slurry.

[0109] (2) Conduct a viscosity test on the slurry obtained in step (1). If the viscosity reaches 13500 mPa·s, store and age the slurry for 24 h. If the viscosity does not meet the requirements, add water or silica sol to adjust it to the required viscosity, and then store and age it. Generally, the plugging slurry needs to be stirred for 5 min at a rotational speed of 82 rpm before use.

[0110] Example 5

[0111] This example provides a plugging slurry for a wall-flow honeycomb ceramic filter. The only difference compared with Example 1 is that the proportion of the leveling agent is 0.01%.

[0112] Example 6

[0113] This example provides a plugging slurry for a wall-flow honeycomb ceramic filter. The only difference compared with Example 1 is that the proportion of the leveling agent is 0.5%.

[0114] Example 7

[0115] This example provides a plugging slurry for a wall-flow honeycomb ceramic filter. The only difference compared with Example 1 is that the proportion of the organic binder is 0.05%.

[0116] Example 8

[0117] This example provides a plugging slurry for a wall-flow honeycomb ceramic filter. The only difference compared with Example 1 is that the proportion of the organic binder is 1.2%.

[0118] Example 9

[0119] This example provides a plugging slurry for a wall-flow honeycomb ceramic filter. The only difference compared with Example 1 is that the proportion of the anti-sagging agent is 0.1%.

[0120] Example 10

[0121] This example provides a plugging slurry for a wall-flow honeycomb ceramic filter. The only difference compared with Example 1 is that the proportion of the anti-sagging agent is 1.1%.

[0122] Example 11

[0123] This embodiment provides a plugging slurry for a wall-flow honeycomb ceramic filter, and the only difference compared with Embodiment 4 is that the proportion of the water reducing agent is 0.1%.

[0124] Embodiment 12

[0125] This embodiment provides a plugging slurry for a wall-flow honeycomb ceramic filter, and the only difference compared with Embodiment 4 is that the proportion of the water reducing agent is 2.4%.

[0126] Comparative Examples 1-4

[0127] Comparative Examples 1-4 respectively provide a plugging slurry for a wall-flow honeycomb ceramic filter, and the only difference compared with Embodiment 1 is that organic binder, anti-sagging agent, leveling agent and water reducing agent are not added in sequence.

[0128] The plugging holes are carried out with the plugging slurries provided in the above-mentioned embodiments and comparative examples, and then dried or fired to prepare a wall-flow honeycomb ceramic filter. The breaking strength of the plugging material is detected. Detection method: Use a customized pin gauge to pressurize the plugging material, and record the pressure when the pin gauge penetrates the plugging material as the breaking strength of the plugging material. And, the detection of light leakage is carried out. The detection method is: Place the product on a glass plate, irradiate it with strong light from below the glass plate along the direction of the product hole, and then check whether there is light passing through the hole from directly above the product against the direction of the light. The results are shown in Table 1.

[0129] Table 1

[0130]

[0131]

[0132] It can be seen from the data in Table 1 as follows:

[0133] (1) It can be seen from the data of Embodiments 1-4 that the plugging slurry provided by the present invention has a strong bond with the pore wall. Under better conditions, when a customized pin gauge is used for pressure testing, the breaking strength of the plugging material reaches more than 10.7 MPa, and there will be no light leakage problem.

[0134] (2) It can be seen from the data of Embodiment 1, Embodiments 5-6 and Comparative Example 3 that the only difference between Embodiments 5-6 and Embodiment 1 is that the proportion of the leveling agent is not within the preferred range of the present invention, and the strength is lower than that of Embodiment 1. The only difference between Comparative Example 3 and Embodiment 1 is that the leveling agent is not added, and the strength only reaches 4.3 MPa, far lower than that of Embodiment 1. Thus, it can be seen that by adding a leveling agent and controlling its mass percentage proportion, the present invention can further adjust the spreading property and slurry hanging property of the plugging slurry, thereby improving the breaking strength of the plugging material.

[0135] (3) From the data of Example 1, Examples 7 - 8 and Comparative Example 1, it can be seen that the only difference between Examples 7 - 8 and Example 1 is that the proportion of the organic binder is not within the preferred range of the present invention, and the strength is lower than that of Example 1. The only difference between Comparative Example 1 and Example 1 is that no organic binder is added, and the strength is much lower than that of Example 1. Thus, it can be seen that by adding an organic binder and controlling its mass percentage proportion, the present invention can further improve the breaking strength of the hole plugging material.

[0136] (4) From the data of Example 1, Examples 9 - 10 and Comparative Example 2, it can be seen that the only difference between Examples 9 - 10 and Example 1 is that the proportion of the anti - sagging agent is not within the preferred range of the present invention, and the strength is lower than that of Example 1. The only difference between Comparative Example 2 and Example 1 is that no anti - sagging agent is added, and the strength is much lower than that of Example 1. Thus, it can be seen that by adding an anti - sagging agent and controlling its mass percentage proportion, the present invention can further improve the breaking strength of the hole plugging material and avoid the problem of light leakage.

[0137] (5) From the data of Example 1, Examples 11 - 12 and Comparative Example 4, it can be seen that the only difference between Examples 11 - 12 and Example 1 is that the proportion of the water - reducing agent is not within the preferred range of the present invention, and the strength is lower than that of Example 1. The only difference between Comparative Example 4 and Example 1 is that no water - reducing agent is added, and the strength is much lower than that of Example 1. Thus, it can be seen that by adding a water - reducing agent and controlling its mass percentage proportion, the present invention can further improve the breaking strength of the hole plugging material and avoid the problem of light leakage.

[0138] In summary, the hole - plugging slurry provided by the present invention has good spreading property and slurry - hanging property, so that when the hole - plugging slurry scraped in or pressed in enters the honeycomb ceramic pore channels, it quickly spreads to the pore wall surface. During the process of the slurry traveling in the pores, the pore walls are completely and densely filled, improving the bonding strength between the slurry and the pore walls, and avoiding the problems of peeling or local light leakage during the drying or firing process.

[0139] The applicant declares that the above - mentioned is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the protection scope and the disclosure scope of the present invention.

Claims

1. A plugging slurry for a wall-flow honeycomb ceramic filter body, characterized in that, The hole-blocking slurry includes inorganic powder and additives; Calculated by mass percentage of the inorganic powder, the additives include: 0.1-1% of organic binder, 0.3-1% of anti-sagging agent, 0.05-0.2% of leveling agent, and 0.3-2% of water reducing agent.

2. The plugging slurry according to claim 1, wherein The hole-blocking slurry includes green-body hole-blocking slurry or fired-body hole-blocking slurry.

3. The plugging slurry according to claim 2, wherein, The inorganic powder of the green-body hole-blocking slurry includes the inorganic formulation of the green body. Preferably, the additives in the green-body hole-blocking slurry further include a solvent. Preferably, the solvent includes water. Preferably, calculated by mass percentage of the inorganic powder, the solvent accounts for 35-50%.

4. The plugging slurry according to claim 3, characterized in that, In the green-body hole-blocking slurry, calculated by mass percentage of the inorganic powder, the additives include: 0.1-0.5% of organic binder, 0.3-1% of anti-sagging agent, 0.05-0.2% of leveling agent, 0.3-2% of water reducing agent, and 35-50% of water.

5. The plugging slurry according to any one of claims 2-4, characterized in that, The inorganic powder of the fired-body hole-blocking slurry includes powder of the same material as the honeycomb ceramic filter, washed kaolin, and calcined alumina powder. Preferably, the powder of the same material as the honeycomb ceramic filter includes any one of cordierite, silicon carbide, or mullite. Preferably, calculated by mass percentage, the inorganic powder includes: 90-95% of powder of the same material as the honeycomb ceramic filter, 1-5% of washed kaolin, and 1-5% of calcined alumina powder. Preferably, the additives in the fired-body hole-blocking slurry further include an inorganic binder. Preferably, the inorganic binder includes silica sol. Preferably, the mass percentage of silicon dioxide in the silica sol is 30-40%. Preferably, calculated by mass percentage of the inorganic powder, the silica sol accounts for 35-50%.

6. The plugging slurry according to claim 5, wherein, In the fired-body hole-blocking slurry, calculated by mass percentage of the inorganic powder, the additives include: 0.3-1% of organic binder, 0.3-1% of anti-sagging agent, 0.05-0.2% of leveling agent, 0.3-2% of water reducing agent, and 35-50% of silica sol.

7. The plugging slurry according to any one of claims 1-6, characterized in that The organic binder includes any one or a combination of at least two of hydroxypropyl methylcellulose, hydroxyethyl cellulose, methylcellulose, water-soluble polyvinyl alcohol, or modified starch. Preferably, the anti-sagging agent includes polyethylene foam balls and / or acrylic water-absorbing resin.

8. The plugging slurry according to any one of claims 1-7, characterized in that, The leveling agent includes polyethylene oxide. Preferably, the water reducing agent includes any one or a combination of at least two of polyether polyol, glycerol, or white oil.

9. A method for preparing a plugging slurry for a wall-flow honeycomb ceramic filter body according to any one of claims 1-8, characterized in that, The preparation method includes: Mixing the inorganic powder and additives in sequence, detecting the viscosity, and storing and aging to obtain the hole-blocking slurry.

10. The preparation method according to claim 9, characterized in that, The preparation method specifically includes the following steps: (1) Pour water or silica sol into a mixer, then add the remaining liquid additives for the first stirring, then add the inorganic powder and the remaining solid additives for the second stirring, then stop the machine and manually turn the bottom of the stirring barrel, and then conduct the third stirring to obtain the slurry; (2) Detect the viscosity of the slurry obtained in step (1). If the viscosity meets the requirements, store and age the slurry. If the viscosity does not meet the requirements, add water or silica sol to adjust to the required viscosity, and then store and age. Preferably, the rotation speed of the first stirring is 80 - 82 rpm; Preferably, the time of the first stirring is 10 - 30 min; Preferably, the rotation speed of the second stirring is 132 - 168 rpm; Preferably, the time of the second stirring is 20 - 40 min; Preferably, the rotation speed of the third stirring is 288 - 292 rpm; Preferably, the time of the third stirring is 10 - 30 min; Preferably, the required viscosity is 8000 - 15000 mPa·s; Preferably, the storage and aging time > 12 h.

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