JP2005169264A - Pulverizing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for pulverizing a solid powder such as glass, ceramics and the like in wet pulverization so that the D90% particle size becomes less than 1 μm without generating the coagulation, and to provide a pulverized material. <P>SOLUTION: The pulverizing method comprises slurrying the solid powder of the glass powder, ceramics powder and the like by a liquid such as water, an alcohol, a hydrocarbon and the like and pulverizing the solid powder while keeping a temperature of the slurry 50°C or lower, thereby satisfying the relation of (D90% particle size)-(D50% particle size)≤0.30 μm. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a pulverization technique for solid powders such as glass and ceramics, and more particularly to a pulverization technique for preventing aggregation. In the present invention, the D50% particle size is a value of 50% cumulative distribution (average particle size), and the D90% particle size is a value of 90% cumulative distribution.

  Conventionally, solid powder is pulverized by dry pulverization of a pulverized raw material in a dry state with a pulverizing medium and wet pulverization of a pulverized raw material mixed with a liquid such as water and then pulverized with a pulverizing medium. It was broken. Dry pulverization has a cost advantage because there is no process such as powder drying, but as the pulverized raw material becomes finer, the collision energy of the pulverization medium is not fully used for the energy used for pulverization, and the energy efficiency of pulverization is remarkably high. Due to the decrease, it was difficult to make the D90% particle size less than 1 μm.

With the recent development of electronics, electronic components are rapidly becoming smaller and thinner, and the materials used therefor are required to be finely pulverized, and a powder having a D90% particle size of less than 1 μm is desired. I came. In view of this, wet pulverization, which has a high production cost but can be made finer, has been used. In particular, pulverization by a “circulating medium stirring pulverizer” that pulverizes while circulating the slurry has been used.

In such a circulating medium agitator and pulverizer, as the pulverization is performed, the temperature of the slurry increases and the viscosity of the slurry increases. Therefore, in order not to increase the viscosity of the slurry, the pulverization chamber is cooled and the slurry is indirectly cooled. The method (patent document 1) and the method (patent document 2) which inject | poured the water cooled with the cooling device into the slurry were performed.

JP-A-3-249958 JP 63-39646 A

  However, there is a batch in which the D90% particle size does not become less than 1 μm even if it is pulverized while controlling the viscosity of the slurry by making a solid powder such as glass or ceramics into a slurry state with a circulating medium stirring type pulverizer that can be most finely divided It was happening.

  The present inventor investigated this cause and found out that aggregation occurred. As a result of earnest research on the cause of this aggregation, even if the solvent forming the slurry is water, it is non-aqueous such as alcohols such as methanol, ethanol and isopropyl alcohol, and hydrocarbons such as nonane and dodecane. Aggregation occurred even if there was, and when the data was analyzed in detail, it was found that the reached average particle size increased as the slurry temperature increased. It was also found that the relationship between the viscosity and the D90% particle size was a slurry having the same viscosity, and that the value of the D90% particle size was higher as the slurry temperature was higher.

  Accordingly, an object of the present invention is to provide a pulverization method and a pulverized product in which agglomeration does not occur and a D90% particle size is less than 1 μm in wet pulverization of a solid powder such as glass and ceramics.

  In order to solve the above problems, the invention corresponding to claim 1 of the present invention is a method for pulverizing a solid powder such as a glass powder or a ceramic powder. The solid powder is slurried with a liquid, and the temperature of the slurry is 50 ° C. or less. The solid powder is pulverized while maintaining at a low temperature. Thus, by setting the slurry temperature to 50 ° C. or lower, the D90% particle size of the solid powder can be less than 1 μm, regardless of whether the slurry is formed with any aqueous or non-aqueous liquid. Preferably it is 45 degrees C or less, More preferably, it is 40 degrees C or less.

The main factor of solid powder agglomeration is due to van der Waals forces. This van der Waals force is an acting force (attraction) between particles, and the specific interaction force increases in inverse proportion to the square of the particle size. Therefore, as the particle size is reduced by pulverization, the specific interaction force increases and aggregation tends to occur. In addition, since the activation of the particle surface also causes aggregation, lowering the slurry temperature reduces the activation energy and suppresses one cause of aggregation.

  The invention corresponding to claim 2 is the solid powder pulverization method corresponding to claim 1, wherein the liquid in which the solid powder such as glass powder or ceramic powder is used as slurry is water, alcohols, or hydrocarbons. When the solid powder is made into a slurry using water, alkali metal elements (Li, Na, K) and alkaline earth metal elements (Mg, Ca, Those containing no Sr, Ba) and boron are preferred. This is because the component composition of the solid powder changes due to elution, but it did not affect the aggregation. That is, if the elution amount with respect to the water of the said component is grasped | ascertained beforehand, a composition change can be suppressed low. On the other hand, when a slurry was formed using alcohols or hydrocarbons, there were almost no easily eluted components.

  In the invention corresponding to claim 3, in the pulverized product obtained by finely pulverizing the solid powder, either the glass powder or the ceramic powder is slurried with a liquid of any one of water, alcohols and hydrocarbons. The D90% particle size and D50% particle size of the pulverized product obtained by finely pulverizing the solid powder while maintaining the slurry temperature at 50 ° C. or less are (D90% particle size) − (D50% particle size) ≦ 0.30 μm. The relationship was satisfied. The particle size distribution curve of the pulverized product satisfying this relationship provides a normal distribution curve in which almost no peaks that are considered to be aggregated are observed. Furthermore, the particle size distribution curve of the pulverized product satisfying the relationship of (D90% particle size) − (D50% particle size) ≦ 0.20 μm can obtain a normal distribution curve having no peak that seems to be agglomerated.

  According to the present invention, by setting the slurry temperature in which the solid powder is contained to 50 ° C. or less, aggregation of the pulverized product can be suppressed, and the D90% particle size of the solid powder can be less than 1 μm.

  An embodiment of the present invention will be described with reference to FIG. FIG. 1 is a conceptual diagram of a circulating medium agitation type pulverizer, and measures the temperature of a pulverization chamber 1 in which a pulverization medium of 0.1 to 1 mmφ can be introduced and an agitator is provided, and the slurry discharged from the pulverization chamber 1. A side temperature section 2, a heat exchanger 3 for adjusting the slurry temperature through the side temperature section 2, a holding tank 4 for storing the slurry discharged from the heat exchanger 3, and a discharge from the holding tank 4 It is formed from a pump 5 that feeds the slurry to be pulverized into the crushing chamber 1.

  The fine pulverization of the solid powder is performed by mixing a solid powder adjusted to a specific particle size or less with water or a non-aqueous liquid into a holding tank 4 and circulating the slurry using the pump 5. In the pulverizing chamber 1, the solid powder is pulverized with an agitator and a pulverizing medium.

  This embodiment is an example when the type of liquid mixed with the raw material of the solid powder to be pulverized is changed using the circulating medium agitating pulverizer of FIG.

First, three kinds of glass powders of SiO ₂ —CaO—BaO, SiO ₂ —CaO—BaO—Li ₂ O, and B ₂ O ₃ —ZnO—SiO ₂ were used as the solid powder. This glass powder is a coarsely pulverized product that passes through a sieve having an opening of 45 μm. Three types of water, ethanol, and isopropyl alcohol were used as liquids for mixing with the glass powder to form a slurry.

Then, 10 liters of slurry is prepared so that the glass powder and the liquid have the solid content concentration shown in Table 1, and this is supplied to the holding tank 4, and the circulation flow rate is 4 liters / minute with the pump 5. The rotational speed of the agitator in the pulverizing chamber 1 is 1800 rpm, 0.3 mmφ, 3 kg of zirconia ball pulverizing medium is placed in the pulverizing chamber 1, and the slurry temperature is set to a temperature range of 30 ° C. to 50 ° C. Table 1 shows the results (samples 1 to 27) of the wet pulverization divided into the adjusted low temperature range and the high temperature range adjusted to be in the temperature range exceeding 50 ° C. and 60 ° C. or less. Note that the D50% particle size and D90% particle size of the finely pulverized product were measured with a microtrack particle size distribution measuring device manufactured by Nikkiso Co., Ltd. FIG. 2 conceptually shows the particle size distribution curve 101 when there is no aggregation and the particle size distribution curve 102 when there is aggregation. When there is no aggregation, there is only peak 103 as shown by curve 101, but when there is aggregation, there are two peaks, peak 104 and peak 105 generated by aggregation, as shown by curve 102.

The results of Table 1 will be described below.
(When SiO ₂ —CaO—BaO glass powder)
When the solvent was water and the slurry temperature was as low as 32 ° C. and 45 ° C., the D90% particle size was finely pulverized to 0.50 μm and 0.55 μm. Further, even when looking at the particle size distribution curve obtained simultaneously with the measurement by the microtrack particle size distribution measuring apparatus, a particle size distribution curve like the curve 101 shown in FIG. 2 having peaks of 0.37 μm and 0.41 μm was displayed. . The values of (D90% particle size) − (D50% particle size) at this time were 0.12 μm and 0.14 μm. On the other hand, when the slurry temperature was 59 ° C., the desired fine pulverization was not performed with a D90% particle size of 1.24 μm. Further, the particle size distribution curve is also a curve like the curve 102 shown in FIG. 2, and the one corresponding to the peak 105 that appears to be generated by aggregation is clearly displayed. 06 μm had two peaks. At this time, the value of (D90% particle size) − (D50% particle size) was 0.69 μm.

  When the solvent was ethanol, when the slurry temperature was as low as 32 ° C. and 44 ° C., the D90% particle size was finely pulverized to 0.53 μm and 0.58 μm. Further, looking at the particle size distribution curve, a particle size distribution curve such as a curve 101 having peaks at 0.41 μm and 0.41 μm was displayed. The values of (D90% particle size) − (D50% particle size) at this time were 0.11 μm and 0.15 μm. On the other hand, when the slurry temperature was 60 ° C., the desired fine pulverization was performed with a D90% particle size of 0.93 μm. However, looking at the particle size distribution curve, it was a curve as shown by curve 102, and a 0.45 μm peak and a small 0.82 μm peak that appears to have occurred due to aggregation were displayed. The value of (D90% particle size) − (D50% particle size) at this time was 0.38 μm.

  When the solvent was isopropyl alcohol, the D90% particle size was finely pulverized to 0.55 μm and 0.56 μm at low temperatures of 34 ° C. and 43 ° C. Also, looking at the particle size distribution curve, a particle size distribution curve such as a curve 101 having peaks at 0.41 μm and 0.45 μm was displayed. The values of (D90% particle size) − (D50% particle size) at this time were 0.15 μm and 0.12 μm. On the other hand, when the slurry temperature was 58 ° C., the desired fine pulverization was performed with a D90% particle size of 0.91 μm. However, looking at the particle size distribution curve, it was a curve as shown by curve 102, and a 0.45 μm peak and a small 0.82 μm peak that appears to have occurred due to aggregation were displayed. The value of (D90% particle size) − (D50% particle size) at this time was 0.35 μm.

From this result, it was confirmed that the SiO ₂ —CaO—BaO glass powder easily aggregates when pulverized in a high temperature state regardless of the type of solvent. Moreover, when water was used as the solvent, it was also confirmed that aggregation occurred clearly from the D90% particle size and particle size distribution curve in the high temperature range. On the other hand, when ethanol or isopropyl alcohol is used as a solvent, a product satisfying the desired D90% particle size ≦ 0.10 μm can be obtained even when pulverized in a high temperature range, but there is a small peak due to aggregation in the particle size distribution curve. It was displayed. When this point was examined, if the difference value of (D90% particle size) − (D50% particle size) was 0.20 μm or less, it was found that a normal distribution curve having no peak due to aggregation was obtained in the particle size distribution curve. It was.

(When SiO ₂ —CaO—BaO—Li ₂ O glass powder)
When the solvent was water and the slurry temperature was as low as 32 ° C. and 43 ° C., the D90% particle size was finely pulverized to 0.49 μm and 0.56 μm. Further, looking at the particle size distribution curve, a particle size distribution curve such as a curve 101 having peaks at 0.37 μm and 0.41 μm was displayed. The values of (D90% particle size) − (D50% particle size) at this time were 0.14 μm and 0.12 μm. On the other hand, when the slurry temperature was as high as 56 ° C., the desired fine pulverization was not performed with a D90% particle size of 1.30 μm. The particle size distribution curve also shows a curve like curve 102, and a peak of 0.49 μm and a peak of 1.06 μm that appears to have occurred due to aggregation were clearly displayed. The value of (D90% particle size) − (D50% particle size) at this time was 0.71 μm.

  When the solvent was ethanol, when the slurry temperature was as low as 33 ° C. and 44 ° C., the D90% particle size was finely pulverized to 0.55 μm and 0.56 μm. Also, looking at the particle size distribution curve, a particle size distribution curve such as a curve 101 having peaks at 0.41 μm and 0.45 μm was displayed. The values of (D90% particle size) − (D50% particle size) at this time were 0.16 μm and 0.14 μm. On the other hand, when the slurry temperature was 59 ° C., the desired fine pulverization was performed with a D90% particle size of 0.99. However, looking at the particle size distribution curve, it was a curve like curve 102, and a peak of 0.45 μm and a peak of 0.82 μm that appears to have occurred due to aggregation were displayed. The value of (D90% particle size) − (D50% particle size) at this time was 0.45 μm.

  When the solvent was isopropyl alcohol, the D90% particle size was finely pulverized to 0.59 μm and 0.59 μm at low temperatures of 35 ° C. and 45 ° C. Further, looking at the particle size distribution curve, a particle size distribution curve such as a curve 101 having peaks at 0.41 μm and 0.41 μm was displayed. The values of (D90% particle size) − (D50% particle size) at this time were 0.16 μm and 0.15 μm. On the other hand, when the slurry temperature was 60 ° C., the desired fine pulverization was performed with a D90% particle size of 0.84 μm. However, the particle size distribution curve showed a curve as shown by curve 102, but a 0.49 μm peak and a very slight peak of 0.82 μm, which appears to have occurred due to aggregation, were displayed. The value of (D90% particle size) − (D50% particle size) at this time was 0.24 μm.

From this result, it was confirmed that even if the SiO ₂ —CaO—BaO—Li ₂ O glass powder was pulverized at a high slurry temperature at a high temperature, regardless of the type of solvent. Further, when the solvent was water, the alkali component (Li ₂ O) was included as a main component in the glass composition, so the alkali component was eluted, but aggregation did not occur in the low temperature range. Further, the same investigation as described above was performed for the particle size distribution curve. When the difference value of (D90% particle size) − (D50% particle size) is 0.20 μm or less, the particle size distribution curve shows a peak due to aggregation. It turns out that the curve without is obtained. However, when a difference value of (D90% particle size) − (D50% particle size) was 0.24 μm and a coating test was conducted, the same evaluation result as that having no peak was obtained. Therefore, if it is a very small peak (in other words, if there is little aggregation), it can be handled in the same manner as that without aggregation. Therefore, when the allowable amount was investigated, it was found that the difference value should be 0.30 μm or less.

(When B ₂ O ₃ —ZnO—SiO ₂ glass powder)
When the solvent was water, the D90% particle size was finely pulverized to 0.53 μm and 0.54 μm at low temperatures of 32 ° C. and 43 ° C. Further, looking at the particle size distribution curve, a particle size distribution curve such as a curve 101 having peaks at 0.34 μm and 0.37 μm was displayed. The values of (D90% particle size) − (D50% particle size) at this time were 0.17 μm and 0.14 μm. On the other hand, when the slurry temperature was 59 ° C., the desired fine pulverization was not performed with a D90% particle size of 1.19 μm. Further, the particle size distribution curve is also a curve like the curve 102, and the peak of 0.53 μm and the peak of 0.89 μm that appears to be generated by aggregation are clearly displayed. At this time, the value of (D90% particle size) − (D50% particle size) was 0.57 μm.

  When ethanol was used as the solvent, the D90% particle size was finely pulverized to 0.58 μm and 0.56 μm at low temperatures of 35 ° C. and 45 ° C. Further, looking at the particle size distribution curve, a particle size distribution curve such as a curve 101 having peaks at 0.41 μm and 0.41 μm was displayed. The values of (D90% particle size) − (D50% particle size) at this time were 0.17 μm and 0.15 μm. On the other hand, when the slurry temperature was as high as 57 ° C., the desired fine pulverization was performed with a D90% particle size of 0.84 μm. However, looking at the particle size distribution curve, it was a curve as shown by curve 102, and a 0.45 μm peak and a small peak of 0.75 μm that appears to have occurred due to aggregation were displayed. At this time, the value of (D90% particle size) − (D50% particle size) was 0.31 μm.

  When the solvent was isopropyl alcohol, the D90% particle size was finely pulverized to 0.54 μm and 0.59 μm at low temperatures of 36 ° C. and 43 ° C. Further, looking at the particle size distribution curve, a particle size distribution curve such as a curve 101 having peaks at 0.41 μm and 0.49 μm was displayed. The values of (D90% particle size) − (D50% particle size) at this time were 0.16 μm and 0.14 μm. On the other hand, when the slurry temperature was as high as 58 ° C., the desired fine pulverization was performed with a D90% particle size of 0.82 μm. However, the particle size distribution curve showed a curve as shown by the curve 102, but a 0.49 μm peak and a very slight peak of 0.75 μm that was considered to have occurred due to aggregation were displayed. The value of (D90% particle size) − (D50% particle size) at this time was 0.22 μm.

From this result, it was confirmed that even when the B ₂ O ₃ —ZnO—SiO ₂ glass powder was pulverized at a high temperature, the slurry easily aggregated regardless of the type of the solvent. Further, the same examination as described above was performed for the particle size distribution curve. If the difference value of (D90% particle size) − (D50% particle size) is 0.20 μm or less, the particle size distribution curve shows a peak due to aggregation. It was found that a normal distribution curve without the curve was obtained. Similar to the above-mentioned SiO ₂ —CaO—BaO—Li ₂ O glass powder, if the difference value was 0.30 μm or less, the same evaluation results as those without aggregation were obtained.

  In summary, when the slurry temperature is low, a fine powder without aggregation can be obtained regardless of the type of glass powder to be crushed and the types of water and non-aqueous solvent. Thus, by obtaining a pulverized product having a D90% particle size of less than 1.0 μm, it is possible to approach the size of the main raw material powder of the capacitor, and even when used as an auxiliary agent for a capacitor, it is more uniform than before. Capacitors that can be mixed and have excellent performance can be obtained. In addition, a low-temperature fired substrate used as a circuit board can be reduced in size and thickness. Furthermore, it is possible to reduce the thickness of an adhesive layer such as PDP, FED, and VFD used as a display device, a dielectric layer, and the like, and to further reduce the thickness of a partition wall.

  In the above-described embodiment, the example is a circulation type medium agitating pulverizer, but the temperature is also used in a rotating ball mill in which solid powder such as glass powder does not circulate or a wet jet mill in which solid powder collides with air and pulverizes. Was maintained at 50 ° C. or lower, a pulverized product with little or no aggregation could be obtained.

  Since the pulverized product obtained by the production method of the present invention has a D90% particle size of less than 1 μm, it can be used effectively as an auxiliary agent for capacitors, using glass powder and ceramic powder. If a low-temperature sintered substrate is prepared, it is possible to obtain a substrate having a thinner thickness than the conventional one. In addition, by adding a filler, a binder, or the like to form a paste, a suitable material for a display device such as PDP, FED, or VFD can be obtained.

It is a conceptual diagram of the circulation type medium stirring crusher used by this invention. It is a conceptual diagram of the particle size distribution curve which shows the presence or absence of aggregation.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Grinding chamber, 2 ... Thermometer, 3 ... Heat exchanger, 4 ... Holding tank, 5 ... Pump

Claims (3)

  A pulverization method characterized in that a solid powder such as glass powder or ceramic powder is slurried with a liquid, and the solid powder is pulverized while maintaining the temperature of the slurry at 50 ° C. or lower.   The pulverization method according to claim 1, wherein the liquid is water, alcohols, or hydrocarbons. A solid powder of any one of glass powder, ceramic powder and magnetic powder was slurried with any liquid of water, alcohols and hydrocarbons, and the solid powder was finely pulverized while maintaining the temperature of this slurry at 50 ° C. or lower. A pulverized product wherein the D90% particle size and the D50% particle size of the pulverized product satisfy the following relationship:
(D90% particle size) − (D50% particle size) ≦ 0.30 μm

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