JP2519101B2 - Beads for crushing and dispersion processing - Google Patents

Description

TECHNICAL FIELD The present invention relates to beads used for crushing / dispersing electronic ceramics such as PZT, dispersing magnetic powders, crushing / dispersing inks / pigments and the like.

(Prior Art) This type of beads is generally a sphere having a diameter of 0.5 to 10 mm, which is put in a medium agitation mill and stirred by a work piece as described above to mix it. Used for crushing and dispersing.

From this purpose of use, physical properties such as wear resistance, compressive strength,
Chemical resistance is required, and since it is a consumable item, it is required to be inexpensive.

Conventional beads of this type include those made of zirconia, glass, alumina and the like.

[Problems to be Solved by the Invention]

Among the conventional beads mentioned above, PSZ (partially stabilized zirconia) (100%) has excellent physical properties such as abrasion resistance, but the unit per kg is 10,000 yen to 15,000 yen. And very expensive, and also alumina (100
%), The unit per kg is about 1,000 yen, which is very low, but there is a problem of poor wear resistance.

In view of the above situation, the present invention has an object to provide beads for pulverization / dispersion which are excellent in physical properties such as abrasion resistance and are inexpensive.

[Means and Actions for Solving the Problems]

In order to achieve the above object, the inventors of the present invention have conducted various experiments and focused on titania (TiO ₂ ) which has been widely used as a white inorganic pigment.

When this titania is used as the raw material, the powder is mixed with a binder, granulated, and then sintered.
With such beads of titania alone, a predetermined pressure resistance could not be obtained, and it was impossible to maintain granulation.

So, after further experimentation, when clay was added to titania to make it sticky, the compressive strength increased more than twice, so we focused on the components of clay and completed this invention here. Came to.

That is, the present invention, by weight ratio, titania: 60 ~ 90
%, Alumina: 10 to 40% and / or silica: 0 to 10% as a raw material, containing a slight amount of impurities, mixed, granulated and sintered to form beads for crushing and dispersion processing.

It should be noted here that trace amounts of impurities are several hundreds of PPM to several hundreds.
Refers to the alkali metal elements such as Na and K of PPM. The clay added to titania originally contains these trace elements.

Further, instead of the alkali and silica, it is possible to use clay or kaolin containing alumina and silica, and the ratio to the clay or kaolin is 30 to 40 for alumina.
%, Silica is 40 to 50%.

Titania is the most chemically and physically stable,
Widely used as a white pigment as described above,
Depending on the crystal system, it is classified into anatase (tetragonal form), rutile (tetragonal form) and brookite (orthorhombic form).
The former two are suitable for use.

Next, a table showing the experimental results based on the blending ratio of various raw materials
Shown in

In this specification, "%" means% by weight unless otherwise specified.

The following facts were found from the above experimental results and FIGS. 1 to 4.

Regarding wear resistance, titania shows the highest value at 60% (Fig. 4). Further, the apparent density and bulk density increase in proportion to the amount of titania (Tables 1 to 7, FIGS. 2 and 3). However, regarding the compressive strength, the required strength cannot be obtained when titania is less than 60% and when it is more than 95%.

From this fact, for the amount of titania, 60-90
% Is appropriate.

Also, the amount of alumina and silica depends on the amount of clay. The clay in the table above contains 35% alumina and 45% silica.
%, So in order to effectively obtain compressive strength, considering the composition of the clay described above, if alumina is 10 to 40%, silica is 0 to 10%, wear resistance is It turned out to be the most suitable.

Regarding the binder, for example, methyl cellulose,
Binders such as CMC (carboxyl methyl cellulose) and PVA (polyvinyl alcohol) are used.

For sintering, the temperature is about 1200 to 1350 ° C. and the firing time is 20 to 30 hours including the cooling time.

[Example 1] Raw material Titania (TiO ₂ ) 70% Alumina (Al ₂ O ₃ ) 25% Silica (SiO ₂ ) 5% Methylcellulose as a binder is added to the above raw material and mixed and granulated.

After drying this, it was placed in a furnace, baked at a temperature of 1300 ° C. for 24 hours, and then naturally cooled to obtain beads having a diameter of 2.0 mm.

5 to 7 show the results of physical property tests comparing the beads of this example with other conventional beads, and the test conditions are shown in the table.

FIG. 5 shows a case where the beads of this example were compared with other conventional beads in terms of abrasion resistance. Regarding the test conditions, 0.2 mill was filled with beads at 25% by volume, ground material was 30% by volume Zr flower and 30% by volume water.
One by one, the pin rotation speed is 2,348 rpm, pin peripheral speed is 4.4 m / s
In the beads of this example, 0.05% per hour
The wear rate is moderate, whereas that of zirconia beads is 10 times that of 0.5%. For glass A beads, it is 0.7%, which is about 14 times, and for glass B beads, it is about 20 times.
The wear rate is 1.0%, and that of alumina beads is about 8 times as much as 0.4%.

Note that this is the case of mounting filled with the crushed object, but in the case of dry sliding with 50% by volume of water filled without the crushed object, the wear rate is as high as 0.2%. It can be seen that the wear rate is much lower than that of the beads and alumina beads.

FIG. 6 shows the relationship between the solvent viscosity and the wear amount. It can be seen that the wear amount of the beads of this example is smaller than that of the zirconia beads in this case as well.

FIG. 7 shows a comparison of compressive strengths. The beads of this example have a compressive strength about 1.23 times that of zirconia beads. Also, about 1.13 times that of glass A, glass B
1.25 times that of alumina beads and 1.20 times that of alumina beads.

From this, it can be seen that the strength was increased by at least 10 to 20% over the conventional beads depending on the raw material blending and molding method.

[Example 2] Raw material Titania 75% Alumina 20% Silica 5% By the same production method as in Example 1, beads having a diameter of 1.5 mm were produced.

When this was used in a dispersion test during ink production, when the test method was 241 hours at a bead loading of 80% by volume, the abrasion rate was 15.9% for the beads of this example and 25.0% for the beads of hard glass. there were.

Further, it was found that the bead of this example increased the ink discharge amount by nearly 20%, and the ink itself was smooth, and the dispersion efficiency was good. Also, there are almost no cracks,
It only took 1/10 of the other beads to crack.

[Example 3] Raw material Titania 80% Alumina 20% PVA (polyvinyl alcohol) is added as a binder to the above raw material, and mixed and granulated.

After this was dried, it was placed in a furnace, baked at a temperature of 1250 ° C. for 24 hours, and then naturally cooled to obtain beads having a diameter of 0.8 mm.

When this was used for the dispersion test of the electronic component raw material, when the test method was a peripheral speed of 10 m / s and a bead filling amount of 5 kg,
The wear rate per hour was as follows.

Beads of this example 0.07% PSZ zirconia beads 0.03% Alumina beads 2.00% The dispersion efficiency was not much different from that of PSZ zirconia.

The price of the beads in each of the above examples is 3,000 per kg.
It is about 0-3,500 yen, which is equivalent to PSZ zirconia (100%)
It is considerably cheaper than 10,000 to 15,000 yen per kg.

〔The invention's effect〕

As described above, according to the present invention, it is possible to obtain a crushed product that is extremely excellent in wear resistance and compressive strength and can be manufactured at low cost.
It has succeeded in providing beads for dispersion processing, and when this is used, for example, for pulverization / dispersion of raw materials for electronic parts, dispersion of ink, dispersion of paint, etc., the processing can be performed efficiently. Of course, it is possible to prevent contamination of the work piece due to abrasion of the beads, and it does not crack during use,
It has an excellent effect that it can be used stably.

Moreover, not only is the amount of wear small, but even if it wears, when the electronic ceramic material (for example, titanate-based material) is dispersed, the zirconia or alumina beads released by the wear become foreign matter in the dispersed zirconia or alumina beads. However, in the case of titania, there is also an advantage that it is not substantially polluted due to the same substance.

[Brief description of drawings]

1 to 4 are graphs for explaining the operation of the present invention. FIGS. 5 to 7 are graphs showing the physical properties of the beads of the first embodiment in comparison with other beads.

Claims (2)

(57) [Claims] 1. A weight ratio of titania: 60 to 90%, alumina: 10 to 40% and / or silica: 0 to 10% as a raw material, containing a slight amount of impurities, mixed, granulated and sintered. Beads for crushing and dispersion processing. 2. A pulverized product obtained by mixing, granulating, and sintering titania: 60 to 90% by weight and clay containing 30 to 40% alumina and 40 to 50% silica as raw materials. Beads for dispersion processing.