JPS6158873A - Manufacture of ceramic porous body - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing a porous ceramic body having a cell structure of a three-dimensional network skeleton having internal communication spaces.

[Conventional technology]

In general, ceramic porous bodies with a three-dimensional network skeleton structure are produced by immersing a synthetic resin foam with a three-dimensional network skeleton structure in an aqueous ceramic slurry and removing the excess slurry by centrifugal force, aeration, or other methods. It is manufactured by removing it by a combination of processes, drying, and firing.

[Problem that the invention attempts to solve]

However, in this manufacturing method, the skeleton of each tree that makes up the cells of the porous body is made thicker, and in order to give it mechanical strength that can withstand practical use, the synthetic resin foam is mixed with an aqueous slurry of ceramic powder. It was necessary to repeat the operations of immersing the slurry in water, pulling it up, removing excess slurry, and drying it many times, which caused problems in terms of production efficiency and cost.

Attempts have also been made to increase the ceramic powder concentration in the aqueous slurry and to use a highly viscous aqueous slurry to increase the amount of ceramic deposited per treatment cycle in order to reduce the number of repetitions described above. ng of the aqueous ceramic slurry is likely to be formed in the openings of the cells that form the communicating spaces of the resin foam, and therefore it is difficult to obtain a ceramic porous body with less clogging and low pressure loss using this manufacturing method. Ta.

The present invention has been made to solve the above problems, and its purpose is to be able to adhere a large amount of ceramic by impregnating ceramic aqueous slurry a small number of times, and to prevent clogging. An object of the present invention is to provide a method that can produce a small number of ceramic porous bodies.

[Means to solve the problem]

To achieve this objective, the present invention provides a method for producing a porous ceramic body.

A synthetic resin foam is used as a base material, which is immersed in an aqueous ceramic slurry to adhere the ceramic to the foam, dried, and fired to produce a ceramic porous body. The gist of the present invention is to provide a method for producing a ceramic porous body with low ventilation resistance, which is characterized by using a hydrophilic or water-absorbing three-dimensional network skeleton structure synthetic resin foam having communicating spaces.

The present invention will be explained in detail below.

As the hydrophilic or water-absorbing three-dimensional, network skeleton structure synthetic resin foam having an internal communication space used in the present invention, a hydrophilic or water-absorbing urethane foam without a cell membrane is preferably used. As the hydrophilic or water-absorbing urethane foam, urethane foam itself made hydrophilic or water-absorbing, or urethane foam made hydrophilic or water-absorbing by various post-treatment methods, etc. can be used.

As a method to make the urethane foam itself hydrophilic or water absorbent, poly(oxyethylene) polyol, poly(
A method can be adopted in which poly(oxyethylene-oxypropylene) polyol or the like is reacted and foamed with the incyanate component. When poly(oxyethylene-oxypropylene) polyol is used as the polyol component, the oxyethylene component is 50% % or more is preferable, and another method of making the urethane foam hydrophilic or water-absorbing is to disperse an aqueous resin containing a water-absorbing resin,
A hydrophilic or water-absorbing polyurethane foam can be obtained by foaming by adding polyincyanate, water, a catalyst, and other auxiliary raw materials.

On the other hand, urethane foam can be made hydrophilic or water-absorbent by post-treatment by coating the urethane foam skeleton with a hydrophilic or water-absorbing resin. Known hydrophilic or water-absorbing resins can be used, but in order to more effectively achieve the purpose of the present invention, a water-absorbing resin whose water absorption is 10 f@ or more, preferably 50 times or more of the resin weight is used. is preferable, and examples of such resins include acrylic acid-vinyl alcohol copolymer, poly(meth)acrylic acid, sodium poly(meth)acrylate, sodium (meth)acryl-acrylamide copolymer, polyacrylamide, polyethylene oxide , polyvinyl alcohol, j+fi powder or cellulose-polyacrylonitrile graft copolymer hydrolyzate,
A water-insoluble water-absorbing resin obtained by crosslinking carboxymethyl cellulose, inbutylene-pyrohydric maleic acid copolymer, or the like can be used. Although any method can be adopted to coat the skeleton of the foam with the hydrophilic or water-absorbing resin, it is preferable to add the hydrophilic or water-absorbing resin to an organic solvent solution of the adhesive and disperse the resin dispersion. Uniform adhesion can be achieved by immersing a synthetic resin foam having a three-dimensional network skeleton structure in water, pulling it up, removing excess solution by centrifugal force or aeration, or a combination of both, and drying.

The optimum adhesion amount of hydrophilic or water-absorbing resin is water absorption 4 of the resin.
．． Depending on the cell size of the ceramic porous body, the target bulk specific gravity of the ceramic porous body, the number of repetitions of impregnation with the ceramic slurry to achieve the target bulk specific gravity, and the physical properties of the ceramic slurry used. Hikone as appropriate.

Examples of the adhesive include resins that are soluble in organic solvents such as vinyl acetate resin, vinyl chloride resin, phenol resin, methacrylic acid, ester resin, or copolymerized modified products thereof, but are insoluble in water, polybutadiene, and polyisoprene. , styrene-butadiene copolymer, butyl rubber, nitrile rubber, etc., which are soluble in organic/organic materials and water-insoluble, or mixtures thereof are suitable.

Examples of solvents for dissolving or dispersing the adhesive and the hydrophilic or water-absorbing resin include alcohols such as methanol, ethanol, ethyl acetate, toluene, η-hexane, cyclohexane, acetone, methyl ethyl ketone, diethyl ether, and trichloroethylene; Organic solvents such as ester hydrocarbons, ketone ethers, and halogenated hydrocarbons are suitable; the key is that they can uniformly dissolve the adhesive, uniformly dissolve or suspend and disperse the hydrophilic or water-absorbing resin, and
Preferably, the organic solvent is of a type that does not significantly swell the synthetic resin foam serving as the base material of the ceramic porous body and can be relatively easily exerted in the drying process.

The amount of adhesive added to the solvent should be the concentration necessary to reliably bond the hydrophilic or water-absorbing resin to the synthetic resin foam that is the base material of the ceramic porous body, but it is usually the concentration of the adhesive. It is preferably about 2.5 to 30%.

A synthetic resin foam with a three-dimensional network structure is soaked in an organic solvent containing the above-mentioned adhesive and a hydrophilic or water-absorbing resin, pulled up, excess liquid is removed by centrifugal force or aeration, and the resin is dried. to the right. This material is immersed in an aqueous ceramic slurry, the excess liquid is removed by centrifugal force or aeration, or a combination thereof, and then dried. If necessary, this operation is repeated until the desired amount of ceramic coating is achieved. By firing, it is possible to obtain a ceramic porous body having a three-dimensional, network-like skeletal structure with internal communication spaces.

The aqueous ceramic slurry used here consists of fine powder of ceramic raw materials such as cordierite, mullite, alumina, silica, lithium-aluminosilicate, and magnesia, a binder such as polyvinyl alcohol and carboxymethylcellulose, and a peptizing agent such as sodium silicate. and water, etc.

Here, as a ceramic raw material, Tsuudiera 6Q? Fuito M~! By using a material consisting of ==fy parts of ffi, 3 μO of lithium-aluminosilicate salt and 5 parts of lumi, the surface strength is improved and a ceramic porous body with a good appearance in which the skeleton of the surface portion is less likely to be damaged can be obtained.

[For production]

In the method for producing a ceramic porous body of the present invention, a hydrophilic or water-absorbing three-dimensional network skeleton structure synthetic resin foam having an internal communication space is immersed in an aqueous ceramic slurry. The amount of ceramic deposited has increased significantly compared to conventional products, and there is less clogging, so
The number of immersions can be reduced compared to the conventional method.

Furthermore, by treating a synthetic resin foam that has already been coated with ceramic with the hydrophilic or water-absorbing resin dispersion, it is possible to significantly increase the amount of ceramic coating when immersing it in an aqueous ceramic slurry. , the number of immersions can be reduced compared to the conventional method.

The ceramic porous body obtained in this way is melt-fused tr.
It can be used for applications such as i filter materials, automobile exhaust gas purification catalyst supports, other industrial catalyst supports, and high-temperature heat insulating materials, and new applications such as heat exchangers are also expected. The present invention provides ceramic porous bodies used for these purposes,
The present invention provides a method for manufacturing at low cost by reducing the number of manufacturing steps and increasing production efficiency, and has the following characteristics: a ceramic porous body with less clogging.

〔Example〕

Next, the present invention will be described in more detail with reference to Examples and Comparative Examples; however, the present invention is not limited to the following Examples unless it exceeds the gist thereof.

Example 1, Ratio Example 1, 200 g of a crosslinked water-absorbent resin whose main component is a copolymer of vinyl alcohol and acrylic acid was added to 500 g of a 40% methanol solution of vinyl acetate, and 20,001:1 of methanol was added and the mixture was stirred well. A urethane foam having a three-dimensional network skeleton structure without a cell membrane with a diameter of 6 cm and a thickness of 5 cm, 20 cells/inch, was immersed in water and then pulled up. Excess liquid was removed using a centrifuge, and then the foam was placed in an oven at 100°C. Dry.

On the other hand, 4.5 parts of polyvinyl alcohol, 0.2 parts of sodium silicate, and water were added to ±100 parts of the cordierite mixture to prepare an aqueous slurry of cordierite. The slurry concentration was approximately 2.0 voids at room temperature. This slurry was impregnated with urethane foam coated with the water-absorbing resin and immediately pulled up, centrifuged and dried to obtain a green sample (Example 1).

On the other hand, a green sample was obtained in the same manner using hydrophobic urethane foam which was not subjected to the adhesion treatment of water-absorbing resin (Comparative Example 1).

The operations of impregnating the ceramic slurry, removing excess slurry, and drying were considered to be one cycle, and the relationship between the number of cycles and the hair density of the sample was as shown in Table 1.

Table 1 The dried green sample was fired at 1300°C to obtain a porous ceramic body.

The compressive strength and pressure loss values of the ceramic porous bodies are also shown in Table 1.

As a result, the bulk specific gravity exceeded 0.4 for the water-absorbing resin-attached sample after two cycles of treatment, whereas four cycles of treatment were required when no water-absorbing resin was attached. The water-absorbing resin-adhered sample has less clogging than the sample not containing the water-absorbing resin, and this is clearly shown in the result that the pressure loss is small despite the large bulk density.

〔Effect of the invention〕

As detailed above, the method for producing a ceramic porous body of the present invention uses a wood-philic or water-absorbing three-dimensional network skeleton structure synthetic resin foam as a base material, and mixes this into an aqueous ceramic slurry. This is a new manufacturing method in which ceramic is adhered to the foam by dipping, followed by drying and firing.The amount of ceramic deposited by one impregnation is two to ten times that of the conventional method, so dipping in ceramic slurry is required. , removal of excess slurry, and repetition of drying can be reduced, and productivity can be greatly improved.

In addition, due to the water absorption effect of the hydrophilic or water-absorbing synthetic resin foam, the ceramic slurry, which has become more viscous on the skeletal surface, adheres uniformly to the skeletal surface, making it possible to produce ceramic porous bodies with less clogging and a good appearance. .

Claims (1)

[Claims] A synthetic resin foam is used as a base material, which is immersed in a ceramic water column slurry to adhere the ceramic to the foam, dried, and fired to produce a ceramic porous body. A method for producing a ceramic porous body with low ventilation resistance, characterized by using a hydrophilic or water-absorbing three-dimensional network skeleton structure synthetic resin foam having communicating spaces.