JPS59174562A - Porous ceramic body and manufacture - 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 The present invention relates to a method of manufacturing porous ceramic bodies. When industrially produced, conventional porous ceramic bodies had a density of approximately 0.697. However, according to the method of the present invention, a manufacturing method has been discovered that allows for even lower density and also achieves both dimensional stability and cell uniformity. That is, the porous ceramic body of the present invention has higher corrosion resistance and better corrosion resistance than conventional porous ceramic bodies.
It has excellent properties such as chemical resistance, moisture resistance, microbial resistance, and heat resistance, and can further expand its useful properties, such as weight reduction due to porosity and suction properties due to capillary action. Therefore, by effectively utilizing these properties in various applications, for example, furnace materials, gas and liquid filtration materials, insulation materials, construction materials, refractory bricks, carriers for catalysts, heat generating materials, stove sheets, adsorbents, etc. It can be used in many ways.

On the other hand, various methods have been proposed for manufacturing these porous ceramic bodies, but the present inventor has effectively utilized the foaming technology used to obtain polyurethane foams, water-based polyurethane foams, etc. The present invention has been completed by obtaining a porous ceramic body that could not be obtained.

A basic example of polymer foams obtained by known techniques or foamed ceramics utilizing these foaming techniques is described in Japanese Patent Publication No. 12.9.27 of 1982; can be classified into two methods. One is JP-A No. 48-81907, JP-A No. 52-77114, JP-A No. 5
No. 4-167158, No. 57-149862, No. 57
-22160 etc., a method of utilizing a polyurethane foam skeleton, adhering a slurry ceramic to it, drying it, and then firing it.
A method using a three-dimensional mesh foam, or a second method described in patent specifications such as JP-A-54-12927, JP-A-56-41868, JP-A-56-145153, and JP-A-57-47756. This method utilizes the foaming effect of a substance that contains incyanate.

Therefore, the above method requires a step of obtaining a foam skeleton as typified by JP-A-52-77114, and
In particular, the biggest drawback is that the practical process is complicated due to the use of a large amount of alkaline aqueous solution. In addition, for this type of porous ceramic, the process up to obtaining the polyurethane skeleton is particularly important and influences the characteristics of the ceramic.

Regarding the second method, since it is a direct foaming method of the ceramic material, it is particularly difficult to obtain uniform porous ceramics or low-density ceramics. In terms of strength, maintaining the original shape during the drying process, etc., shrinkage was particularly noticeable as large foams were obtained, making it difficult to obtain the desired product.

The present inventor applied the knowledge obtained through research on inorganic-containing polyurethane foam and the fixation of soil and sand with water-soluble urethane prepolymers, and developed a direct foaming method using urethane prepolymers in slurry-like ceramics that could not be obtained with conventional technology. The present invention was completed by obtaining a low-density uniform foam with -bk44==.

That is, the urethane prepolymer used in the present invention is a reaction product of a polyoxyalkylene polyol with an average molecular weight of 1,500 to 8,000 (ethylene oxide content of 60 to 98% by weight) and an incyanate compound, and a polyurethane prepolymer with an average molecular weight of 1,500 or less. Furthermore, it can be obtained by using in combination, if necessary, a reaction product of a polyol having an ethylene oxide content of 60% by weight or less and an isocyanate compound. It also requires the inclusion of an organic incyanate compound.

The ceramic raw material used in the present invention can generally be made into a sintered body by heating to a high temperature, and is not particularly limited, but examples thereof are described below. Clay, feldspar, kaolin, bentonite, silica, chinastone, limestone, magnesite, barium carbonate, mullite, alumina, zircon, zirconia, rutile, silicon carbide, cordierite, etc. are used alone or in combination. The amount of the urethane prepolymer used in these ceramic raw materials is mixed and used at a ratio of 5 parts by weight or more and 50 parts by weight or less with respect to 100 parts by weight of the ceramic raw materials.

If less than 5 parts by weight is used, it will be difficult to hold the ceramic foam in the slurry, and if it is more than 50 parts by weight, it will be difficult to control foaming and the raw material will simply be wasted.

In addition, various additives are generally used to obtain the desired porous ceramic, but there are no particular limitations on these additives in the present invention.

Examples of commonly used additives include the use of polysiloxanes such as polydimethylsiloxane/polyoxyalkylene copolymers as open-cell agents, or commonly used surfactants to control the air bubbles. As blowing agents that can be used in combination with silane-based and titanium-based coupling agents to obtain preferable results, in addition to the use of incyanate compounds as in the present invention, use of foaming surfactants, trichloromonofluoromethane, Low boiling point hydrocarbons such as dichlorodifluoromethane, butane, isobutane, etc., and other organic binders such as polyvinyl alcohol, polyvinyl butyral, methyl cellulose, ethyl cellulose, etc. as necessary, water-based urea resin, water-based melamine resin, ah emulsion, etc. Used for synthetic rubber latex, viscosity reducing solvents, etc. However, the present invention is not limited to these additives.

The water used has the function of slurrying the ceramic and raw materials, and the role of a blowing agent using carbon dioxide gas generated by the reaction of incyanate groups.

The urethane prepolymer used in the present invention will be explained below. The urethane prepolymer containing an organic incyanate compound acts as a foaming agent and binder through reaction with water, and serves as a medium that facilitates the slurry action of ceramics. In the present invention, which has an average molecular weight of 1,500 to 8,000 and has an ethylene oxide content, which plays an important role in maintaining the shape until it is fired, as well as obtaining a uniform foamed state that suits the purpose. A urethane prepolymer using a polyoxyalkylene polyol having 60% by weight or more and 98% by weight or less, or a urethane prepolymer using a polyol with an average molecular weight of 111,500 or less and an ethylene oxide usage amount of 60% by weight or less in the urethane prepolymer. Urethane prepolymer 10 is used in combination at a ratio of less than 10% by weight, and is further added to maintain foaming power, deformation resistance after foaming, and strength.
The purpose can be achieved by including 50 parts by weight or less and 2 parts by weight or more of the organic incyanate compound relative to 0 parts by weight. This is not only due to the general effects of the prepolymers mentioned above, but also because it is possible to obtain large-sized porous ceramics without shrinkage during the baking salt process, in order to obtain low density and uniform porous ceramics that could not be obtained with conventional techniques. I can do it.

In the present invention, the average molecular weight is 1500 to 5oooy, and the amount of ethylene oxide used is t6o weight percent or more.9
The use of polyol is limited to 8% by weight or less, because if the average molecular weight is less than j500, a homogeneous water-containing ceramic slurry cannot be obtained, and on the other hand, the average molecular weight is too low.

If it exceeds this, the strength of the water-containing ceramic slurry becomes weaker, making it impossible to obtain a uniformly porous ceramic.

Therefore, in order to improve the strength of the foam and obtain a low-density porous ceramic, a urethane prepolymer using polyoxyalkylene polyol, which is a hydrophilic polyether with an average molecular weight of 1,500 to 8,000, has an average molecular weight of 1,500 to 8,000. An industrially effective porous ceramic body can be obtained by using a urethane prepolymer using a polyol with an ethylene oxide content of 60% by weight or less, or an organic isocyanate compound.

The urethane prepolymer used in combination with the secondary polymer has trifunctional or higher functionality and 60% by weight or less of ethylene oxide, and good performance can be obtained even if it does not contain ethylene oxide.

The urethane prepolymer used in the present invention is usually synthesized separately, but in practice, it is a mixture of a polyoxyalkylene polyol with an average molecular weight of 1500 to 8000 and a greborimer with the aim of producing a polyol with an average molecular weight of 15Ω0 or less. The polyol estimated from the ratio can be mixed and reacted with the isocyanate compound.

The polyoxyalkylene polyol used in the present invention is not limited to the following, but can be added to an initiator compound with ethylene oxide, propylene oxide, butylene oxide, etc. to form a block or body/dam. .

For example, when obtaining a bifunctional polyoxyalkylene polyol, the initiator compound may include water, ethylene glycol, diethylene glycol, propylene glycol, diethylene glycol, 1.4 ethylene gel +) 1-l, etc., and when obtaining a trifunctional polyoxyalkylene polyol, , glycerin, trimethylolpropane, etc., diglycerin, pentanylthritol, etc. as tetrafunctional, sorbitol as 1.6 functional as sorbitol, 7-functional as examples.

Trifunctional or higher functional polyols with an average molecular weight of 1,500 or less include, for example, glycerin, trimethylolpropane, diglycerin, pentanylthritol, sorbitol, sucrose, and alkylene oxides with an average molecular weight of addition using these compounds as initiators. Polyol tn of 1500 or less can be prepared and used.

Incyanate compounds used in the present invention include z4-tolylene diisocyanate, 16-1 lyre/diisocyanate, diphenylmethane diisocyanate, naphthalene/
Diincyanate, triphenylmethane triisocyanate, paraphenylene diisocyanate, hexamethylene diicyanate, xylylene diisocyanate,
Examples include inophorone diynnaneanate, synchhexylmethanediyn7anate, and polymeric isocyanate.

The present invention will be specifically explained below using polyurethane grebolimer production examples and examples.

Production Example 1゜Polyoxy 4 and dialkylene polyol 300II with an average molecular weight of 3000 obtained by addition reaction of ethylene oxide and propylene oxide at a weight ratio of 80:20 using ethylene glycol as an initiator were placed in a four-eye flask equipped with a stirrer. After removing and sealing with nitrogen, stirring (il-) was started. At 40°C, tolylene diisocyanate (TDI) 87
The temperature was raised to 80°C. Since it was slightly exothermic, it was cooled and kept at 80°C ± 2°C, and the reaction was carried out for 4 hours. Closed. Production examples 2 to 8 are produced in the same manner. Comparative products 1 to 4 were manufactured.

Summarize the results in one list.

Example 1゜Alumina (A-1a), 30 parts, Zenshi Feldspar (F-1) 4
0 parts, 30 parts of protozoan viscosity were taken out, 50 parts of water was added thereto, and the mixture was thoroughly mixed.
Add 50 parts of polymer, mix thoroughly with a mixer for 30 seconds, pour into a mold, pre-dry in an oven at 80°C for about 8 hours, heat up to 400°C in 5 hours, and mix at 40°C.
After heat treatment at 0±30℃ for 1 hour, it cleaved at about 8 o'clock and became 1200℃.
The temperature was raised to .degree. C., baked for about 1 hour, and then allowed to cool. The obtained porous ceramic had the physical properties shown in the attached table.

From the above results, it is possible to obtain a porous ceramic with a good cell appearance, and a ceramic with low shrinkage and low density.

From the above results, the manufacturing method of the present invention is superior to the conventional technology in that it is possible to produce a low-density porous ceramic body, as well as to achieve cell uniformity, reduced shrinkage rate, and large-sized foam. It is clear that the porous ceramic body and the method for producing the same according to the present invention are industrially very effective and standard.

Claims (1)

[Claims] (1) A mixture of 5 to 50 parts by weight of a urethane prepolymer containing water and an organic isocyanate compound to 100 parts by weight of the ceramic raw material is foamed and then fired. A method for producing a porous ceramic body characterized by: (2. Ceramic raw material 10 according to claim 1)
2. A porous ceramic body and a method for producing the same according to claim 1, wherein the porous ceramic body and its manufacturing method are adjusted to 0 parts by weight, f: 10 parts by weight, and 0 parts by weight. (3) The urethane prepolymer according to claim 1 comprises a polyoxyalkylene polyol and an incyanate compound having an average molecular weight of t, soo to s, ooo and an ethylene oxide content of 60% to 98% by weight. reaction product or average molecular weight 15
A method for producing a porous ceramic body according to claim 1, characterized in that a reaction product of a polyol having an ethylene oxide content of 00 or less and an ethylene oxide content of 60 weight percent or less and an incyanate compound is used in combination. (4) In the urethane prepolymer described in claim 1, the polyoxyalkylene polyol having an average molecular weight of 1,500 to 8,000 has a difunctionality of 1 or more and an average molecular weight of 150.
2. The method for producing a porous ceramic body according to claim 1, wherein the polyol having 0 or less has trifunctionality or more. (5) When using the urethane prepolymer described in item 1, the ratio of the urethane prepolymer using a polyol with an average molecular weight of 1500 or less to the urethane prepolymer using a polyalkylene polyol with an average molecular weight of 1500 to 8000 is 50% by weight. % or less, and the method for producing the porous ceramic body according to item 1. (6) The incyanate compound used in claim 1 is an organic incyanate compound, and its usage ratio is 2 to 1 part by weight per 100 parts by weight of the urethane prepolymer.
A method for producing a porous ceramic body, characterized by using a urethane prepolymer containing 0.00 parts by weight.