JPS6024073B2 - Manufacturing method of ceramic porous material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel method for manufacturing porous ceramic materials.

More specifically, it relates to a method for producing a porous ceramic material by mixing a ceramic raw material with a raw material for polyurethane foam in the presence of water, passing through a polyurethane foaming process, and then firing the ceramic raw material. .

That is, the present invention relates to a method of manufacturing a fired ceramic porous material using polyurethane foaming. The ceramic porous material of the present invention has characteristics that conventional ceramic materials have;
For example, it has heat resistance, corrosion resistance, abrasion resistance, mechanical strength, etc., and because it is a porous material, it can be used in a wide range of applications.

For example, filtration media for various gases, aqueous solutions, oils, and molten metals for physical and chemical industry and medical use, diaphragms for separating and concentrating gases and liquids, various adsorbents, catalysts for the chemical industry,
Catalysts or their carriers for automobile exhaust gas, exhaust gas denitrification, etc.
Can be used as a support, etc.

In addition, it can be used in a variety of other fields, such as various building materials that take advantage of its nonflammability and heat resistance, materials for industrial equipment, sound-absorbing materials, and powder transportation that utilizes gas blowing. The method for producing a ceramic porous body according to the present invention has many features.

First, the foaming process can utilize conventional polyurethane foaming technology.

The characteristics of conventional polyurethane foaming technology are {1) It uses an easy-to-handle liquid as a raw material, ■ It can be molded with relatively simple equipment, {3} It has a fast reaction, foaming, and curing time, and it hardens at room temperature. [4] The selection range of raw materials is wide, and it is relatively easy to control the reaction by selecting the catalyst. [5] It is possible to select so-called closed cell or open cell. The specific gravity of the molded product can be easily selected from a wide range, and 7) molded products of any shape can be freely produced. Even in the production according to the present invention, the characteristics of the polyurethane foaming technology can be fully utilized to varying degrees.

Next, a urethane bond is formed between the polyisocyanate compound and a hydroxyl group-containing compound as raw materials for foaming, and a urea bond is formed by the reaction between the polyisocyanate compound and water, and foaming is caused by the generation of carbon dioxide gas. Another feature is that it gives rise to

That is, since a large amount of ceramic raw materials are mixed in the raw materials, the presence of water is necessary for mixing and stirring the raw materials, and water is the source of the foaming action of polyurethane.

However, if a large amount of ceramic raw materials are mixed without mixing water, a substantially large amount of polyisocyanate compounds and hydroxyl group-containing compounds will be required from the processing surface, so the amount of ceramic raw materials in the total amount of raw materials will be small, and the post-process will be This causes a big problem during firing, and the object of the present invention cannot be obtained. The mixing of water serves the purpose of increasing the amount of ceramic raw materials in the total amount of raw materials. The amount of water mixed in the present invention is 48 to 64 parts by weight per 100 parts by weight of the ceramic raw material.

If the amount of water mixed is less than 4 parts by weight, it will be difficult to uniformly disperse the ceramic raw material in the hydroxyl group-containing compound, and
If the amount exceeds 4 parts by weight, it becomes difficult to form urethane bonds and the strength of the resulting foam decreases, and more water remains in the polyurethane foam, requiring a large amount of heat when drying the polyurethane foam. Furthermore, the shrinkage of the polyurethane foam increases. When mixing a ceramic raw material with a hydroxyl group-containing compound, it is also possible to use a liquid other than water together with water to improve the above-mentioned problems.

Typical examples of liquids other than water include acetone and ethyl acetate, but in this case as well, it is basically necessary to mix water. In addition, the mixing of water produces urea bonds due to the reaction between the polyisocyanate compound and water, which together with other bonds, mainly urethane bonds, has sufficient heat resistance to prevent the molded product from deforming during the firing process. It will give gender.

In order to improve heat resistance, there is no need to dimerize, trimerize, etc. of the isocyanate group. A further advantage of the present invention is that by strictly controlling the ratio of ceramic raw materials and polyurethane raw materials as described below, a more stable ceramic porous material can be obtained. That is, the weight ratio of organic polyisocyanate compound A, compound B having two or more hydroxyl groups in the molecule, and ceramic raw material C is {A+B}/{A
+B+C};U (in this case, U is referred to as urethane ratio for convenience), it is necessary to adjust U to a range of 0.1 to 0.5. When U is less than 0.1, the amount of ceramic raw material is too large relative to the amount of polyurethane, making it difficult for foaming to occur, and even if foam molding is possible, the molded product is brittle and difficult to handle. On the other hand, when U is 0.5 or more, the strength of the foamed molded product increases, but since the amount of ceramic raw materials mixed is too small, cracks are likely to occur during the firing process, and in severe cases, the original shape cannot be maintained during firing. Destroy. In addition, in the present invention, mixing water and polyurethane raw materials,
In other words, the amount of A+B to 10 parts by weight of water is 31 to 1.
It is necessary to adjust the amount to 8 parts by weight, and if the amount of polyurethane raw materials mixed is less than 31 parts by weight, a large amount of water will remain in the polyurethane foam, requiring a large amount of heat for drying, and The shrinkage of the foam increases.

Typical organic polyisocyanate compounds used in the present invention include TD1, MD1, liquid MD1, crude M dish 1, and the like.

Furthermore, a so-called prepolymer, which is a reaction product of an organic polyisocyanate compound and an active hydrogen atom-containing compound, can also be used. Alternatively, mixtures with the above compounds or prepolymers are also practical. Of course, a wide variety of other organic polyisocyanates can also be used in the present invention. It is well known in the related industry that compounds having two or more hydroxyl groups in the molecule can be broadly classified into long-chain polyols with relatively large molecular weights and polyols with relatively small molecular weights, that is, chain extenders or curing agents. That's true. Examples of long-chain polyols include so-called polyether-based polyols such as polypropylene glycol, polyethylene glycol, and polytetramethylene ether glycol, and so-called ester-based polyols such as polyethylene adibate, polybutylene adipate, and borocaprolactone. Also,
In addition to these systems, there are also so-called polybutadiene systems and polymer polyol systems. A long chain polyol contains two or more hydroxyl groups in the molecule. Examples of polyols with relatively small molecular weights include ethylene glycol,
One or more of the above hydroxyl group-containing compounds, of which diethylene glycol, butylene glycol, propylene glycol, dipropylene glycol, triethanolamine, trimethylolpropane, glycerin, bentaerythritol, etc. are selected arbitrarily, are used to form an organic polyisocyanate compound. By arbitrarily selecting , the polyurethanization reaction can proceed easily.

Various catalysts may be used to control foaming reactivity.

As the catalyst for the urethanization reaction and the ureaization reaction, many others such as triethylenediamine, triethylamine, N-methylmorpholine, dibutyltin dilaurate, etc. can be used. The foaming action can basically be made possible by carbon dioxide gas generated by the reaction between water and the organic polyisocyanate compound.

Halogenated alkanes used in general polyurethane foaming, such as trichloromonofluoromethane, methylene chloride, dichlorodifluoromethane and pentane, can also be used in combination with water. Additionally, a surfactant may be added for the purpose of improving the foaming effect.

As the surfactant, one type or a mixture of cationic, anionic, and nonionic surfactants can be used. It is well known in the art that a number of surfactants are effective for use in polyurethane foams, and they also work effectively in the present invention. Typical examples include sorbitan esters of higher fatty acids, alkylbenzole sulfonates, and so-called silicone derivatives, but are not limited to these. In the case of the present invention, it is not necessary to strictly control the so-called NCO index (ratio of NCO groups to active hydrogen groups), which normally needs to be controlled quite strictly in polyurethane foaming.

The ceramic raw material of the present invention generally includes those obtained as Akatsuki compacts.

Kaolin, clays, silica, alumina, feldspar, chest right, mullite, calcium oxide, magnesium oxide, silcon, zirconia, beryllium compounds, titania, iron oxide,
Examples include silicon carbide, thorium oxide, chromite ore, synthetic cordierite, and synthetic steatite.
It is not limited to these.

The manufacturing method according to the present invention is basically as follows.

Arbitrarily selected ceramic raw materials are thoroughly ground and mixed using a ball mill or the like.

In this case, one or both of water and a hydroxyl group-containing compound can be mixed simultaneously. Water is added to the pulverized mixture of the above ceramic raw materials and stirred to form a uniform slurry, and a hydroxyl group-containing compound, if necessary, a catalyst, a blowing agent, and a surfactant are mixed into this slurry, and the mixture is sufficiently uniformly mixed and stirred. By mixing and stirring the organic polyisocyanate compound into the mixture thus prepared, the mixture undergoes the steps of reaction, foaming, and oxidation. At this stage, a suitable mold is prepared in advance, and a foam molded product of any shape can be obtained by injecting the stock mixture into the mold. In addition, by adjusting the viscosity by adjusting the amount of water added, etc.
It can be operated with a simple polyurethane foaming machine with a mixing head. In this manner, it is possible to obtain a foam having a polyurethane foam as its backbone and supporting ceramic raw materials.

Subsequently, the foam is heated to sinter the ceramic raw material.

Various heating methods can be used for firing,
It is obvious in the ceramic industry that the optimum temperature differs depending on the ceramic raw material used, and that the heating rate and cooling rate should be thoroughly investigated and tested in advance, taking into account deformation, cracking, etc. of the molded product. As a heating means, it is common to use an electric furnace, a gas furnace for temperature control, or a mobile tunnel pot.

In the temperature raising process, gas generation occurs due to decomposition or carbonization of the polyurethane foam component at around 250 qo. In some cases, the furnace is equipped with a blower and smoke exhaust device to send out the generated gas, and in some cases carbonization is carried out by avoiding the presence of a large amount of air, but in either case, the flames emit violently. Combustion is not recommended. Gas generation ends at about 350 oo to about 45,000 oo, and then heating is continued to burn the ceramic raw material. In particular, when heating, it is necessary to pay close attention to the conditions until the end of gas generation. When the firing is completed in this way, the ceramic porous material of the present invention can be obtained. Next, examples of the present invention will be described. The middle part of the example represents parts by weight. Comparative Example A ceramic raw material mixture was prepared by finely pulverizing 145 parts of Orin, 44 parts of Agase, and 11 parts of M and 0.

Next, 200 parts of water is mixed with the mixture to create a uniform slurry. 10 parts of PPGMS300 (OH value = 32, manufactured by Mitsui Nisso Co., Ltd.) and polyether P2000 (OH value = 50)
Uniformly mix 1 part (manufactured by Adeka), 1.2 parts of ethylene glycol, and 0.1 part of triethylamine, and
A polyol is prepared by adding and mixing 0.2 part of neLVIO0 (manufactured by Nippon Oil Co., Ltd.) to olybu.

Next, 180 parts of the slurry is mixed with 10 parts of the polyol, and then stirred while mixing 10 parts of MDI-CR (NCO value = 30%, manufactured by Mitsui Nisso Co., Ltd.).

In this case, the urethane ratio U=0.18, but the ceramic raw material 1
0 parts by weight to 10 parts by weight of water, and 22 parts by weight of A+B to 100 parts by weight of water, which are outside the scope of the present invention. 3. After stirring the existing sand, pour it into the mold.
Foaming begins and a cured product is obtained.

The cured product is dried in a 70 qo dryer for 5 hours and then moved to the next step. The drying shrinkage rate of the above foam was tested and the value was 10%.
The foam was significantly warped and deformed. The cured product was placed in an electric furnace and heated for 135q from a variable temperature to 300oo.
0/hr, 4 days 0/hr from 300oo to 1000qo
Raise the temperature at r.

In this case, decomposition gas is generated from around 20,000 and 400,000.
Gas generation almost stops at around ℃. Then 5400/
After reaching 1350 0 at a temperature increase rate of 1 hr, at the same temperature
．． Retain the period. After that, the temperature was lowered to 120,000 in 45 minutes, and then 670/hr to 100,000, 10
The temperature is lowered from 00° C. to room temperature at a rate of 48 do/hr. The material thus obtained has a specific gravity of 0.7 and a compressive strength of 40.
It is a porous and strong ceramic porous material with a bending strength of 40 ko and a bending strength of 40 ko. Note that the average pore size was approximately 20 mosquitoes. Example 1 10 parts of finely ground feldspar, 20 parts of kaolin, 10 parts of quartz and 256 parts of water were mixed to create a uniform slurry.

Next, after uniformly mixing 100 parts of PPGMS200 (OH value = 23, manufactured by Mitsui Nisso Co., Ltd.) and 5 parts of Glycerin 2 no Miyako SHI90 (surfactant: manufactured by Toray Silicone Co., Ltd.),
4 parts of the mixture and 1 part of dibutyl tin dilaurate are mixed into the slurry.

Subsequently, 40 parts of M Blood 1-CR are added and mixed and stirred (in this case, urethane ratio U=0.10, 64 parts by weight of water to 10 parts by weight of ceramic raw material, A+ to 10 parts by weight of water).
B31 parts by weight).

When the mixture is poured into a mold after stirring for 1 minute, foaming begins approximately 1 minute after the start of injection, continues to foam gradually for about 2 minutes, expands to approximately twice its volume, and then stops foaming.

The drying shrinkage rate of this foam was 4%. The foam was placed in an electric furnace, and the temperature was raised from room temperature to 45,000 in 4 hours, and from 450oo to 125,000 in 6 hours,
After 30 minutes, the temperature was maintained at 125,000 and then gradually cooled. Specific gravity 0.
A very strong ceramic porous material with a compressive strength of 50k9/cm and a bending strength of 50k9/cm and a pore diameter of approximately 10 m was obtained.

Example 2 16 parts by weight of feldspar, 12 parts by weight of flint, and 120 parts by weight of kaolin were added and mixed with 200 parts by water to form a uniform slurry.

Next, in a mixture of 100 parts of polyether P2000, 12 parts of ethylene glycol, and 1 part of dibutyltin dilaurate, 525 parts of the slurry was mixed, and further R-
1 part of No. 11 (trichloromonofluoromethane: manufactured by Goi Chloro Chemical Co., Ltd.) was added and mixed and dispersed.

Separately, 200 parts of PPGMS and 200 parts of TDIIOO were mixed and reacted at 80 qo for 2 hours until the free NCO value was 1.
4.4% prepolymer is made.

Subsequently, 218 parts of this prepolymer is mixed with the ceramic material mixture, stirred, and then poured into a mold to foam and harden (in this case, the urethane ratio U=0.48, based on the cloud content of the ceramic raw material 10). A + B 18 parts by weight for 5 parts by weight of water and 10 parts by weight of water).

The foam experienced a volumetric expansion of approximately 2 times.

The drying shrinkage rate of the foam was 2°C. Next, the foam was placed in an electric furnace, and the temperature was increased at a total temperature increase rate of ℃/hr from room temperature to 700℃, a temperature increase rate of 60qo/hr from 700℃ to 1000℃, and a temperature increase rate of 38℃/hr from 1000℃ to 1150℃/hr. h
Heating was continued at a temperature increase rate of r, and the temperature was maintained at 1150 pm for 1 hour for firing, followed by slow cooling.

The obtained ceramic material has a specific gravity of 0.6 and a compressive strength of 32.
It was a strong ceramic porous material with an open-cell, spongy structure and a bending strength of 33k9/kg/kg.

Note that the average pore diameter was approximately 2 ribs.

Example 3 12 parts of anti-firestone, 90 parts of kaolin, 12 parts of feldspar
Mix 0 parts with 15 parts of water to create a uniform slurry. Next, after mixing 200 parts of PPGMS, 10 parts of glycerin, and 1 part of SHI90, 3 parts of the mixture is mixed with 450 parts of the slurry, and 0.8 part of dibutyltin dilaurate is mixed and stirred. . After that, MDI-
CR3 anchor is added, mixed and poured into the mold (in this case U=0.16, 48 parts by weight of water to 100 parts by weight of ceramic raw material, 41 parts by weight of A+B to 10 parts by weight of water). The mold used is a polypropylene cylindrical mold with an outer diameter of 5 mm, a circular depression of 20 mm, and a height of 15 mm. After injection, approximately 1. The volume expands to the level of a needle sound, and almost fills the cylindrical mold.

After drying at 70 oo for 6 hours, the molded product is taken out. The drying shrinkage rate of the molded article was 2%. Since the surface part of the molded body was more dense than the inside part, that part was removed.

The molded body obtained in this way was placed in an electric furnace and heated to 200 qo.
Temperature increase rate of 50℃/hr to 500℃ from 200qo
The heating rate was 113°C/hr to 113°C/hr from 500pm to 115030, and the heating rate was 230°/hr at 1150qo.
After holding for a period of time, slowly cool.

A strong ceramic material having a cylindrical shape and a pore diameter of approximately one cell was obtained.

The drying shrinkage rate of the foam obtained in the above example was 100×
A 40×20 skin sample piece was dried at 80 oo for 22 hours, and it is the percentage of the shrinkage length of the sample piece divided by the length of the original sample piece.

In addition, the compressive strength of the porous materials obtained in each of the above examples is 20×
This is the value obtained by compression testing a sample piece measuring 20 x 2 m in size at a speed of 5 ribs/min, and the bending strength is obtained by compressing a sample piece measuring 150 m in length x 20 m in width x 1 m in length with a distance between supports of 10 m. This is the value obtained by a bending test at a speed of 5 per minute.

Claims (1)

[Claims] 1. Organic polyisocyanate compound A is added to a mixture of compound B having two or more hydroxyl groups in the molecule, ceramic raw material C, and water.
In the method of manufacturing a ceramic porous material by adding and reacting with each other to form a foam and firing the foam, each of A and B
, C is as follows: {A+B}/{A+B+C}=U(
U in the formula (urethane ratio) is in the range of 0.1 to 0.5, and water is in the range of 48 to 6 parts by weight per 100 parts by weight of ceramic raw materials.
4 parts by weight, and A+B is 31 to 189 parts by weight based on 100 parts by weight of water.