JPH02225359A - Production of ceramics or ceramic material using oxide-based raw material - Google Patents

Abstract

PURPOSE:To provide plasticity required for molding process by adding a sugaralcohol to an oxide-based raw material of ceramics. CONSTITUTION:In production of ceramics or ceramic material using an oxide- based raw material, a sugaralcohol is added to the oxide-based raw material. A monosaccharide alcohol and/or oligosaccharide alcohol comprising a hexose as a constituent saccharide is preferable as the sugaralcohol. Sorbitol, mannitol, lactitol, etc., are preferable as the sugaralcohol. The amount of the sugaralcohol added is <= about 10% based on the oxide-based raw material and preferably 0.2-5%. For example, feldspar, silica rock, silicate, clay minerals, synthetic kaolinite, spinel, mullite, alumina, zirconia or ferrite may be cited as the oxide- based raw material.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to ceramics and/or ceramics using oxide-based raw materials.
Or, regarding a method for producing a ceramic material, more specifically, reducing the viscosity of a slurry prepared using an oxide-based raw material by adding a sugar alcohol to the oxide-based raw material, or a clay prepared using an oxide-based raw material, The present invention relates to a method for producing plastically formed ceramics and/or ceramic materials that improves formability by increasing or imparting plasticity to kneaded clay.

(Conventional technology) As raw materials for ceramics, silica stone, which is a non-plastic raw material,
Feldspar, alumina, magnesia, zirconia, spinel,
Oxides such as ferrite and clay minerals such as hydrous oxides such as kaolinite, which is a plastic raw material, are used. Conventionally, Cerami Nox has been made by adding water and small amounts of additives to these raw material powders, mixing them, then molding, drying, and firing.

In other words, clay is used, which is made by adding highly plastic clay (mainly composed of clay minerals) to non-plastic raw materials such as silica and feldspar to improve moldability (workability, plasticity, shape retention, etc.). New ceramics are made by adding a small amount of clay or organic plasticizer to highly pure non-plastic raw materials such as alumina. Furthermore, in order to increase the purity of the ceramics, fine ceramics are made by adding only a mechanical plasticizer to the synthesized ceramics and firing them.

For example, alumina (α-Ah(h)) is extremely abundant as a resource and has excellent properties such as mechanical strength, chemical durability, thermal shock resistance, and electrical insulation properties, and it Compared to other products, its production volume is large and its uses are extremely wide.Furthermore, the alumina powder raw material is finely divided (particles of 1 us or less) and highly purified (99.9% purity) in consideration of sinterability and homogeneity. Since its development, materials have become highly functional and are widely used in the fields of electronic materials, biological materials, and optical materials.

Recently, the depletion of high-quality clay resources that provide plasticity has become a serious problem in Japan's ceramics industry, and with the expectation of an alternative raw material, a method for producing synthetic kaolinite has been developed. Despite rapid progress, synthetic kaolinite currently lacks the high plasticity found in natural clay.

In the forming process of new ceramics or fine ceramics, multiple synthetic organic materials (plasticizers, binders, etc.) are used to improve formability, so new degreasing and forming processes are required in the firing process. At the same time, the shrinkage caused by firing becomes significantly larger than that of ceramic crystals, causing problems such as large distortions in shape. For this reason, there is currently no technology to completely form a desired ceramic shape, and there is a strong desire to develop additives such as plasticizers that can solve these problems.

By the way, the production of ceramics consists of the processes of preparing powder raw materials, molding, and firing, and each of these processes is closely related to each other. Especially in powder raw materials and their preparation, the selection of raw materials and forming aids and control of slurry properties have a great impact on the evaluation of ceramic materials. Ceramic molding methods include pressurization, extrusion, casting, and injection molding, and the molding method is selected depending on the shape of the material, purpose of use, etc. In the end, yield and economic efficiency in the manufacturing process are particularly important. be done.

Among the above molding methods, the slurry casting method (sludge removal, solid method)
As for the equipment, it only requires porous mold material, does not require expensive equipment, and has many advantages such as being suitable for manufacturing products with complex shapes and manufacturing ceramics in small quantities of a wide variety of products. In addition, in recent years, coupled with the development of ceramic turbochargers for automobiles, the slurry casting method has gained further recognition and attention.

The basic requirements of the cast molding method are how to form agglomerated particles (2
The question is whether to obtain a slurry in which the primary particles are peptized without causing the formation of secondary particles. Furthermore, in the case of slurry for casting, since the amount of water absorbed by porous mold materials such as plaster molds is extremely small, it is necessary to reduce the amount of water in the slurry to make it highly concentrated, and to lower its viscosity. In addition, it is essential to maintain appropriate liquidity. In general, it is said that the standard for high-concentration slurry is that the packing density (bulk density) of the particles of the molded body is preferably 60% or more of the theoretical density. If the porosity is less than this, sintering will not be achieved sufficiently due to the high porosity, and the molded product will shrink significantly, rendering it of no practical value.

Therefore, it is essential to stably hold and disperse the powder in a dispersion medium, and for this purpose, inorganic electrolytes (hydrochloric acid, tetramethylammonium hydroxide, water glass) or organic electrolytes (ionic surfactants), etc. is used as a dispersant. However, since the former slurry whose pH has been adjusted with acids and alkalis significantly damages the plaster mold, in recent years polycarboxylic acid type ammonium salts (anionic), which cause a decrease in the interfacial energy between solid and liquid, have generally been oxidized. It is used as a dispersant for physical raw material powders.

In addition to the dispersant (or peptizer), the slurry contains binders (polyvinyl alcohol, cellulose, wax emulsion, acrylic emulsion, etc.) and plasticizers (glycerin, etc.) to impart strength to the molded product. , polyethylene glycol, etc.), wetting agents (n-butanol, isopropanol, etc.), and antifoaming agents may be added as molding aids.

When a peptizer and a binder are added in combination when preparing this slurry, the viscosity of the slurry becomes extremely high, and for example, in the case of a highly concentrated slurry, casting becomes impossible, resulting in a decrease in the peptization state. There is.

This seems to be caused by the compatibility between the organic materials.

That is, for example, the raw material alumina used when manufacturing alumina ceramics for the purpose of compactness has an average particle diameter of about 0.5! Since they are fine particles around na and have high surface activity, these fine particles tend to strongly aggregate. For this reason, it is necessary to use large amounts of water and molding aids to prepare the slurry. On the other hand, regarding dispersants and binders among forming aids, although they are anionic materials with the same effect, when they are used in combination, the viscosity of the slurry increases. However, at high slurry concentrations or large amounts of binder, casting becomes extremely difficult. That is, in preparing the slurry, the peptization state of the slurry may be poor depending on the characteristics of the alumina powder raw material or the compatibility of the forming aid.

However, these organic materials (dispersants, binders)
Due to the complexity of their composition, their effects and actions have not been fully elucidated scientifically.

Regarding the stability of alumina slurry, it may gel over time due to small amounts of components contained in the raw material alumina.
Another problem is that the pot life of the slurry is significantly shortened. Furthermore, in the ceramics industry, there are significant barriers in terms of know-how, and as a result, sufficient solutions to these problems have not yet been obtained.

[Problem that the invention is trying to solve]

As mentioned above, in the production of ceramics using oxide-based raw materials, whether in the field of traditional ceramics or new materials such as fine ceramics, a small amount of addition during molding provides good moldability. Additives are necessary, and it can be said that the quality of the additives not only affects the quality of the ceramic product but also determines whether or not it can be manufactured.

However, high-quality clay, which is a natural resource, is in danger of being depleted in Japan, and synthetic kaolinite, which should compensate for this, has not yet been given sufficient plasticity. Furthermore, regarding fine ceramics, which is expected to be a new material,
Since the raw material powder is highly pure and has fine particles, it has poorer plasticity than natural raw materials, and additives that impart plasticity to it are required not to impair the high purity of the raw material.

The purpose of the present invention is to provide these oxide raw materials with formability, which is a common issue in the production of ceramics using these oxide raw materials, thereby eliminating the depletion of plastic raw materials for traditional ceramics and oxidation to create new materials. The aim is to solve problems in manufacturing fine ceramics using physical raw materials.

Another object of the present invention is that when preparing an alumina slurry, the slurry can be prepared using conventionally known organic binders for slurries (for example, polyvinyl alcohol-based, cellulose-based, wax-based emulsions, acrylic acid-based emulsions, etc.). It does not have the effect of increasing the viscosity of the alumina, and can prevent the gelation phenomenon caused by the raw material alumina. Even for dispersants (salts), organic molding aids, sugar alcohols, can improve the peptization of slurry and maintain its stability.
The objective is to produce ceramics or ceramic materials with high interparticle strength. The present invention can extend the pot life of slurry by achieving the above object,
Furthermore, since the high concentration and low viscosity slurry required for molding can be easily prepared, the preparation of the slurry can be easily controlled, and there is no need to worry about workability problems. Furthermore, the particle filling of the molded body is made homogeneous, and since the molding aid is safe and ash-free, it does not have a negative effect on the sintered body H1 weave (and is intended to improve the density of ceramics). It is.

[Means to solve the problem]

The present invention provides a means for imparting high plasticity necessary for the molding process by adding sugar alcohol to an oxide-based raw material for ceramics.

The sugar alcohol used in the present invention is a carbohydrate t
I! The reducing group (aldehyde group, ketone group) of n is replaced with an alcoholic hydroxyl group, and although it exists in nature and may be produced by microorganisms, industrially it is usually used as a catalyst for reducing sugars. It is produced by reduction with hydrogen in the presence of.

Most sugar alcohols can be used, but raw sugars include monotin and/or monosaccharide alcohols in which the reducing group of oligosaccharides is replaced with alcoholic hydroxyl groups, or / and oligosaccharide alcohols are useful as industrial raw materials. As the monosaccharide alcohol, sorbitol and mannitol are preferable.
As an oligosaccharide alcohol, 3 tl from disaccharide alcohols such as maltitol and lactitol! More than 10 alcoholic beverages! Oligosaccharide alcohols up to the alcohol level can be used alone or in combination. Commercially available sugar alcohols, such as Oken Chemical Products (Nisii),
The constituent sugar is glucose and its bond type is α-1,4 or /
Oligosaccharide alcohols having α-1,6 bonds can also be used.

As the oxide-based raw material used in the present invention, any oxide-based raw material that is a raw material mineral for ceramics, such as feldspar, semi-feldspar, silica, silicates, and various clay minerals, can be used, and synthetic or processed oxidation As the physical raw material, any synthetic oxide raw material for ceramics can be used, such as synthetic kaolinite, spinel, mullite, alumina, zirconia, and ferrite.

The purity of the alumina material used in the present invention is preferably 90% or more, particularly preferably 99% or more, and high-purity ceramics can be manufactured from high-purity fine alumina particles with a purity of 99.9% or more.

The amount of sugar alcohol used in the present invention is 10% or less by weight based on the oxide raw material, preferably 0.1% or more, more preferably 0.2% to 5%.
%.

The sugar alcohol can be added to the oxide raw material in advance to the powder of the oxide raw material and/or water, or can be added at the same time when preparing the slurry or kneaded clay before molding. Further, when granulating an oxide-based raw material as a ceramic material, it can be used by adding it to water and/or oxide-based raw material powder and/or other additives in advance.

The molding method is cast molding, pressure molding, molding using a potter's wheel, etc., as long as it is molded with moisture.
It can be used in any molding method.

In the old days, when the fine powder of oxide-based raw materials or the crystals constituting them came into contact with each other through water during molding and slid together while causing friction, the sugar alcohol The present invention was completed based on the assumption that the surfaces of these powders and crystals act on the surfaces of these powders and crystals, as well as water, to improve the slippage between the surfaces of these powders and crystals, and after conducting various studies.

For example, zero sorbitol is added to the slurry used for casting.
．． When about 5% to 5% is added, the viscosity of the slurry decreases significantly. Taking advantage of this property, it is possible to reduce the water content of the slurry and perform high-density casting. This water-reducing effect is also observed for clay used in potter's wheel molding. In other words, it has been revealed that sugar alcohol further enhances the action of water, which is thought to bring about a sliding effect between oxide fine particles.

Furthermore, considering that the unique plasticity of clay is also a property brought about by the sliding properties of water and the surface of clay particles, we investigated substances that would impart fluidity and water-reducing properties to non-plastic or low-plastic oxide materials. have found that adding sugar alcohol to oxide-based raw materials imparts or increases fluidity and plasticity, resulting in improved moldability.

These effects are similar for all oxide-based raw materials such as natural minerals, synthetic kaolinite, and high-purity oxides. It is thought that this is a common effect that true alcohol has on the physical properties of .

As for the effect of the degree of polymerization of sugar alcohol, as the degree of polymerization increases, the dry strength of the ceramic molded body improves, so that a binder effect is also observed.

Furthermore, as specifically explained in the examples below,
According to the present invention, when sugar alcohol is added to the alumina slurry, the viscosity of the slurry decreases and the fluidity increases, so that the water content of the slurry can be reduced. Even when raw material alumina causes gelation, gelation can be suppressed by adding sugar alcohol. Furthermore, since sugar alcohols are nonionic, they can exhibit their properties without adversely affecting other ionic additives.

In this way, the favorable effects of sugar alcohol on alumina slurry impart desirable physical properties to the alumina slurry as a ceramic slurry, and provide better conditions for the ceramic forming process, resulting in improvements in physical properties such as the strength of the dry body and the strength of the ceramics. There are effects such as contributing to improvement.

Furthermore, in the spray granulation of alumina powder as a material for pressure molding, the reduction in slurry viscosity improves the fluidity of the spray liquid, making it possible to spray a highly concentrated slurry, and also to break up the droplets. It has been observed that it has an effect on improving the

As described above, the action of the sugar alcohol is to not only reduce the viscosity of the alumina slurry, but also to improve its stability and give the alumina slurry desirable physical properties as a ceramic slurry without adversely affecting other agents.

(Examples) Hereinafter, the present invention will be specifically explained according to Examples.
It goes without saying that the technical scope of the present invention is not limited to these examples. In addition, in the following example, "
%" and "Part J" are based on weight unless otherwise specified.

Jitugabetsudosaba (consisting of feldspar and quartz) 30 parts, waxite 20 parts, pottery stone 20 parts, and clay 30 parts (moisture 15.5 parts)
%) in a vacuum clay kneader, add 0% of commercially available oligosaccharide alcohol (Nikken Chemical: SE 57, moisture 30%).
．． By adding 2%, 0.5% or 1.0% and water, three types of kneading with a moisture content of 20.0% were prepared.

Next, in an extrusion molding machine, the width of the body is 60, the length is 100n+m,
Three types of molded bodies each having a thickness of 20 InI11 were created.

This molded body was dried at 30°C to 40"C for 48 hours to obtain a dry body, and then fired at a maximum temperature of 1280"C for 33 hours to prepare three types of fired bodies.

As comparative examples, molded bodies, dried bodies, and fired bodies were prepared in the same manner without adding oligosaccharide alcohol.

The bending strength of the dried product and the wear area (■) of the fired product were measured according to the ceramic tile testing method of JIS A3209. The number of samples was 10 for each section, and the average values are shown in Table 1.

As shown in Table 1, the bending strength of the dry body was the same as that of the comparative example (7
)20.52kgf/cli1 comparison T-21,08~
The amount increased to 22.78 kgf/d, and the wear loss of the fired body decreased from 10.3 mg in the comparative example to 9.1 to 8.0 mg. Both values indicate that dense filling is performed during molding, and the strength of intermediate process products and finished ceramics is increased.

Table-1 Addition amount of sugar alcohol 0.2%"l O,5%"1.0%"10%" Abrasion loss of fired body 9.1 B, 7 8.0
10.3 ■ *l; Example, *2: Comparative Example 1 Using the method of Example 1, add sorbitol (Oken Kagaku: water 30%) as a sugar alcohol to 0.2% of the clay. %,
By adding 0.5%, 1.0% or 2.0%, clay, molded bodies, dried bodies and fired bodies were prepared in the same manner. The bending strength of the dried body and the abrasion loss of the fired body were measured and shown in Table 2.

In this example, a remarkable effect was shown when the amount of sorbitol (30% moisture) added was 0.5 to 2.0% to the clay (15.5% moisture). That is, the bending strength of the dry body was 22.85 to 25.2 kgf/cJ compared to the comparative example of 20.48 kgf/cJ.
The result was 91 kgf/c+j, and the abrasion loss of the fired body was 9.4 to 8.9 cm, compared to 10.4 mg in the comparative example.

Table = 1 Amount of sugar alcohol added 0.2%"0.5%"11.0%" 2.0%111
30% kaolin, 30% mackerel, 30% bone ash and clay
Water was added to bone china clay consisting of O% to give a moisture content of 25%, and 1%, 2%, 3%, and 5% of lactitol (30% moisture) were added to the clay, respectively. After stirring and mixing, it is made by hand using a plaster mold.
It was molded into a short fence type test piece with a thickness of 6 to 7 mm, a width of 18 mm, and a length of 70 mm.

0%1 Tetos beads were dried at 110° C. for 12 hours to prepare a dried body, and then further fired at 1280″C for 6 hours to obtain a fired body.

As a comparative example, a dried product was prepared in the same manner as in Example 3 without adding lactitol, and then fired to prepare a fired product.

The bending strength of the dried product was measured using an autograph manufactured by Konsei Seisakusho, and the results are shown in Table 3. As shown in the table, the bending strength increased significantly with the addition of lactitol, and the bending strength in the example was 20.
7-51. The value of Okgf/cJ was obtained. The white skin of the fired product was also extremely good.

Table - Yulactitol addition amount Formability 41 1% 0 2% 0 3% ◎ 5% ◎ 0% (Comparative example 3) △ Dry bending strength 20.7 29.6 30.9 51.0 11.0 kgf/cod *1 ◎: Very good, ○: Good, △: Poor fruit 11 [1] Water was added to white porcelain clay consisting of 40% kaolin, 45% mackerel, and 15% clay so that the moisture content was 23%, To this, commercially available oligosaccharide alcohol (Nikken Chemical: SE 5
7, moisture 30%) respectively 1, 2.3 and 5% 4
After adding in stages, molded bodies, dried bodies and fired bodies were prepared in the same manner as in Example 3, and the bending strength of the dried bodies was measured.

The bending strength of the dry body was significantly improved as in Example 3, and was 18.0 kgf/C [29 compared to 11 in the comparative example].
．． It became 4 to 54.4 kgf/cJ.

Wheat-1 1% 0 2% 0 3% ◎ , 5% ◎ 0% (Comparative Example 4) △ 29.0 45.8 40.2 54.4 Hydrothermally synthesized using alumina and silica as raw materials To the synthetic kaolinite prepared by adding 12.4.6% of sorbitol (Ikken Kagaku: Sorbitol S, water 30%),
Furthermore, the same amount of water as the synthetic kaolinite was added and kneaded, and then left to mature at 40°C for one week. The plastic water content (pr) of the aged sample was measured by the Pefferkorn method, and the amount of unfrozen water in the sample was measured by a differential scanning calorimeter. The results are shown in Table 5 together with Comparative Example 5 in which sorbitol was not added. .

As is clear from the PI values in Table 5, the amount of water required to impart plasticity decreases in inverse proportion to the amount of sorbitol added, indicating that the clay can be used as a plastic clay. This effect is supported by an increase in the amount of unfrozen water, which is thought to have a plasticity-enhancing effect, and since this value is comparable to that of natural kaolinite, it can be expected that synthetic kaolinite will play the role of plastic clay.

, Table J- 2% 4% 6% 41.4 0.0493 39.8 0. ．． 0709 39.4 0.0642 Actual difference example - Kayadesper C-72 (manufactured by Nippon Kayaku) as a dispersant in zirconia containing 94% ZrO and 25% Y2O
0.3% and oligosaccharide alcohol (Nikken Chemical Nini E 2
0) 0.45% was added to make the slurry concentration 74%,
After mixing in a ball mill for IO hours, casting was performed in a plaster mold to prepare a cylindrical molded body with a diameter of 8 nm and a length of 100 m.

After drying the molded body at 110°C for 16 hours to obtain a dry body, the temperature was gradually raised in an electric furnace and the temperature was increased to a maximum temperature of 1 soo'c for 3 hours.
A fired product was obtained by firing for a period of time.

As a comparative example, the viscosity and bending strength of the dry body of 6 slurries prepared by casting, drying, and firing in the same manner without the addition of oligosaccharide alcohol were measured, and the results are as shown in Table 6. there were.

The apparent viscosity of the slurry was approximately 75% of that of the comparative example, and the bending strength of the dried product was 145% of that of the comparative example. Even in it
It was +73.

Example 6 296 cps 34.9 K
The examples of gf/ct & ceramic production were molded by a casting method that best reflects the physical properties of the slurry, and all steps were performed up to sintering. In addition, the preparation method and the method of measuring the properties common to Examples 1 to 7 were as follows.

1. For the slurry, add a predetermined amount of additives (dispersant, sugar alcohol, etc.) to the solid content of alumina, and add this to an arbitrary amount of distilled water (water content of the slurry). The melted material and raw material alumina (99% pure low-soda fine alumina or 99.99% pure high-purity easily sinterable alumina) were placed in an alumina pot mill (SSA type, manufactured by Nihon Kagaku Togyo ■) for dispersion treatment ( The resulting slurry was transferred to a polytetrafluoroethylene container (500 zl) and stirred for approximately 16 hours with a sealon film (manufactured by Fuji Film ■) to prevent water volatilization. I left it still.

In the cast molding, a solid round bar sample (8IIIfflΦX 100 mmL) was molded in 0.5 hours using a plaster mold (JIS R-9111).

3. After thoroughly air-drying the obtained molded sample at room temperature, it was further dried for 4 times.
Drying treatments were performed at 0°C and 115°C for 24 hours each. The molded body is calcined at 700-900°C and then heated to 1600°C.
It was fired in

The viscosity of the 1 group U1 constant slurry of Ball-J was measured by measuring the shear flow curve using a rotational viscometer (Model E manufactured by Tokyo Keiki) at a constant slurry temperature of 20°C. The apparent viscosity was determined from the friction stress at a rotor rotation speed of 5 rpm.

5. The bulk density of the molded and fired products was determined by the underwater gravimetric method.
The bending strength was measured by an autograph (AG 500 model manufactured by Shimadzu Corporation) using a two-point bending method according to JISR160.

Table 7 shows the product names and compositions of the tang alcohols used in the following examples.

Alcohol Note) *Nisui 500 has an α-1,6 bond, and the others have an α-bond.
It is a 1,4 bond. Note that both "Nisii" and "Sorbitol F" are products of Ikken Kagaku.

Actual drawing 11 The raw material alumina fine powder used was low soda alumina (AI-160sG-1) produced by the Bayer method, and the dispersant was polycarboxylic acid type ammonium salt (Kaya Disper C-7).
27 anionic), the sugar alcohols shown in Table 7 were added, and water was added to prepare a slurry with a concentration of 80%.

The obtained slurry was left to stand for about 16 hours after preparation, and the viscosity of the slurry was measured after that, and the results are shown in Table 8.

As is clear from the results in Table 8, in both cases of monosaccharide alcohol (Sorbitol F) and each oligosaccharide alcohol, the viscosity of the slurry decreases as the amount added increases, and especially the monosaccharide alcohol (Sorbitol F) )In Case of,
The thinning effect of the slurry is clearly shown.

Example 1 In the method of Example 7, 0.6% of Nisui 20 was added as the alcohol, 0.3% of Kaya Disper 0-72 manufactured by Nippon Kayaku Ql was used as the dispersant, and the water content was 16% and 17%, respectively. %, 18% or 20% slurry preparation,
An alumina ceramic cylinder was produced by casting, drying, pre-firing, and firing. The results of measuring the apparent viscosity of the slurry at 20°C are shown in Table 9, along with a comparative example in which no sugar alcohol was added.

011LL In this example, as the raw material alumina, ammonium dawsonite (N11.^l (OH) z
High-purity easily sinterable alumina (purity 99.99%) synthesized by thermally decomposing C(h 2 ) was used.

The dispersion characteristics of this raw material are such that the purity of the alumina is extremely high, so sorbitol or Nisii 20 is added to the slurry using the raw material alumina fine powder shown in Example 7. The stability of the slurry viscosity was tested by observing the change in slurry viscosity over time in both cases.

The results obtained are shown in Table 10.

The raw material alumina used caused a gelation phenomenon as shown in Comparative Example 8 in Table 10 during the standing period of the slurry due to trace components contained in the raw material, and the viscosity became unmeasurable. On the other hand, when monosaccharide alcohol or oligosaccharide alcohol was added, as shown in Example 9 in Table 10, the gelation phenomenon of the slurry could be completely prevented and controlled. Note that isoprobil alcohol or the like may be used as a wetting agent. However, as shown in Comparative Example 8 in Table 10,
It is impossible to stably maintain the peptized state due to changes over time.

Dispersant is compatible. However, conventionally known organic binders used together with dispersants are mainly anionic dispersants, and there has been no binder compatible with cationic dispersants.

Table 1 shows the properties of alumina slurry when an anionic or cationic dispersant is used, with and without the addition of oligosaccharide alcohol (Nisui 30) according to the present invention. As is clear from the characteristics of the slurry in Table 11, when oligosaccharide alcohols are added according to the present invention, the viscosity-reducing effect of the slurry is observed even for cationic dispersants.

;ii -'1° A dispersant (Kaya Disper C-72) and 0.6% oligosaccharide alcohol were added to the raw material of low soda fine alumina (Al2S33G-1) to prepare a slurry with a concentration of 82%, and this slurry was cast. Molded. The properties of this cast body were as shown in Example 11 in Table 12.

Since this slurry is highly concentrated, the bulk density of the molded product is 12
: Norumi 9 Use the same high-purity easily sinterable alumina as in Example IO, use the anionic dispersant and cationic dispersant shown in Table 13, and add Nisii 30 in the amount shown in Table 13. In this example, the molded body was fired at 1350°C after slurry preparation and casting molding were carried out according to a conventional method. The cast molded body and the fired body exhibited a particle filling rate of 64% with respect to the theoretical density (4,0), and also exhibited a high dry strength value.

Fruit Eggplant Soil 1 Low soda fine alumina (LS-23), dispersant (Kaya Disper C-72) and oligosaccharide alcohol (Nisui 3)
0) was added in an amount of 0.3% or 0.6% to prepare a slurry having a slurry concentration of 82%, and this slurry was cast.

The properties of this cast body were as shown in Example 12 in Table 12. As is clear from the values of Comparative Example IO in Table 12, the addition of oligosaccharide alcohols according to the invention significantly increases the dry strength values.

The properties were as shown in Example 13 in Table 13.

As is clear from the results in Table 13, the addition of oligosaccharide alcohol was able to increase the dry strength of both cationic and anionic dispersants compared to Comparative Example 11 in Table 13. . Furthermore, even after the compact is fired, it maintains the desired characteristic values without reducing the ease of sintering of alumina, and no abnormal grain growth is observed when the fibers of the sintered compact are observed. There wasn't. Therefore, it is clear from this result that the alumina fine particles are uniformly filled.

2% of Thor F made from 13;1 aluminum was added, and water was added thereto so that the water content was 35%, and a slurry was prepared in a conventional manner using a ball mill. This slurry was granulated and dried using a spray dryer model MSD-3 manufactured by Makino Iron Works. The conditions for granulation drying are: disk rotation speed 20.0OOr, pom, hot air temperature 190°C, input temperature 190°C, output lower temperature 5°C, slurry supply rate 21! / It was time. Table 14 shows the physical properties of the obtained alumina granulated powder.

0.5 of Nippon Kayaku ■Kaya Disper 〇-72 as a dispersant for alumina powder Al-160SG manufactured by Showa Denko ■
% and IJ! As alcohol, Solbi [made by Nikken Kagaku ■]
[Effects of the Invention] The effects of the present invention are directly obtained when a mixture (sludge,
The goal is to improve the fluidity of the clay (mixed soil) and give it plasticity.

In the production of ceramics, these effects result in water reduction and density improvement of the molded body, and these effects result in improved strength and accuracy of the molded body. These effects improve the yield of the process and the complex formability, and further reduce the shrinkage rate of the dried body, resulting in an excellent sintered body.

In addition, in the production of ceramic materials, for example, in spray granulation of slurry, granulated powder with good physical properties has been found to improve the fluidity of slurry, reduce water, and improve workability. It becomes easier to obtain.

The effect of applying the present invention from alumina to ceramics or ceramic materials is that the viscosity of the slurry is reduced and stabilized, thereby improving the manufacturing process of ceramics.
In particular, it is important to improve the workability of the molding process. That is, as seen in Example 7, the viscosity of the slurry decreases significantly as the amount of sugar alcohol added increases.

Examples show that this effect of reducing the viscosity of the slurry makes it possible to reduce the water content, which has an important effect on improving the strength of ceramics. The strength of the molded body and fired body is improved by improving the molding density by using a highly concentrated slurry with such a viscosity-reducing effect. This effect was demonstrated in Example 11,
As shown in Example I2 along with a comparative example. Improving the strength of the molded body leads to an improvement in process yield, and improving the strength of the fired body is the most important improvement in the physical properties of ceramics. Even in the spray granulation of granulated powder for pressure molding as a ceramic material, droplet breakage is extremely good due to the improved properties of the slurry, and no slurry adhesion to the disk surface, which tends to be a problem in spray granulation, is observed, making it dry. A remarkable effect of improving workability and powder physical properties, such as improved drying properties, was observed, and the effect of reducing drying costs by using a high concentration slurry was also observed.

The stability of the slurry viscosity may change significantly over time depending on the quality of the alumina powder, and may become impossible to mold due to the increase in viscosity due to gelation. For example, this is the case with Comparative Example 8 in Table 10. Even the slurry using such alumina powder and the slurry to which glue alcohol was added as in Example 9 were stable, with almost no increase in viscosity observed, and even after 16 hours of preparation, the same formability as immediately after preparation was maintained. It was done. As shown in Comparative Example 9, when an anionic dispersant is used to peptize alumina slurry, the viscosity of the slurry increases and a high-concentration slurry with good formability cannot be obtained. However, the viscosity reducing effect of adding sugar alcohol is As shown in Example 10, this effect is fully exhibited not only in the case of a system dispersant but also in a cationic dispersant.

As mentioned above, the effects of the present invention include the fluidity of alumina slurry,
A desirable formulation for ceramic slurry, as it improves stability and can compensate for the shortcomings of other additives.
By expanding the adjustment range of physical properties, it improves the workability of the manufacturing process of ceramics and/or ceramic materials, increases the manufacturing yield, and also increases the strength, which is most important for the physical properties of ceramic manufacturing. be.

The sugar alcohol used in the present invention is a highly pure carbohydrate and contains almost no impurities containing elements other than carbon, oxygen, and hydrogen, so it is gasified during the sintering process, which has a negative impact on sintering. Another advantage of the present invention is that no degreasing process is caused and almost no degreasing step is required.

Claims (15)

[Claims] 1. A method for producing ceramics or ceramic materials, which comprises adding a sugar alcohol in the production of ceramics or ceramic materials using oxide-based raw materials. 2. 2. The manufacturing method according to claim 1, wherein an oxide-based raw material having a purity of 90% or more is used as the oxide-based raw material. 3. 2. The manufacturing method according to claim 1, wherein a natural oxide containing alumina and/or silica as a main component is used as the oxide raw material. 4. 2. The manufacturing method according to claim 1, wherein synthetic kaolinite is used as the oxide raw material. 5. 2. The manufacturing method according to claim 1, wherein alumina having a purity of 90% or more is used as the oxide raw material. 6. 2. The manufacturing method according to claim 1, wherein alumina having a purity of 99% or more is used as the oxide raw material. 7. The manufacturing method according to claim 1, wherein the sugar alcohol contains 25% by weight or more of an oligosaccharide alcohol having a degree of polymerization of 2 to 5. 8. The manufacturing method according to any one of claims 1 to 7, wherein the sugar alcohol is a monosaccharide alcohol and/or an oligosaccharide alcohol. 9. Claim 8 wherein the monosaccharide alcohol is sorbitol and/or mannitol and/or galactitol.
Manufacturing method described. 10. The manufacturing method according to claim 8, wherein the oligosaccharide alcohol contains maltitol and/or lactitol as a component. 11. 9. The production method according to claim 8, wherein the oligosaccharide alcohol contains a sugar alcohol whose constituent sugars are glucose residues and whose bonds are α-1,4 bonds and/or α-1,6 bonds. 12. 2. The manufacturing method according to claim 1, wherein water is added to the oxide-based raw material to prepare a slurry, and the slurry is cast in a mold. 13. 2. The manufacturing method according to claim 1, wherein water is added to the oxide-based raw material to prepare clay, and the clay is plastically formed. 14. 2. The production method according to claim 1, wherein the amount of sugar alcohol added to the slurry is within a range of 5% by weight or less based on the oxide-based raw material. 15. 6. The manufacturing method according to claim 5, wherein the sugar alcohol is added during the alumina peptization stage.