JPH0725657A - Production of slurry for green sheet - Google Patents

Abstract

PURPOSE:To provide a feedstock charging procedure enabling a continuously fed slurry to be homogeneously mixed and dispersed in a slurry production unit for conducting slurry mixing, kneading and defoaming operations. CONSTITUTION:In a method for producing a slurry for green sheets by coarsely mixing, kneading and defoaming a feedstock comprising at least two kinds of ceramic powder, solvent, dispersant and binder, the following procedure is taken: (1) a mixing tank for coarsely mixing the feedstock is charged with the solvent, the 1st ceramic powder smaller in quantity, the 2nd ceramic powder greater in quantity, dispersant and binder, in this order; or (2) said tank is charged with the solvent and dispersant to make a mixed solution which is then charged with the two or more kinds of ceramic powder having been dry mixed homogeneously followed by the binder.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a green sheet slurry for producing a ceramic multilayer wiring board by stacking a plurality of green sheets and then firing them together.

[0002]

2. Description of the Related Art Conventionally, a slurry for a green sheet for producing a ceramic multilayer wiring board has been prepared by using a batch type ball mill and a defoaming device to mix, knead and defoam raw materials in units of manufacturing lots of ceramic powder. Was going on.

[0003]

Generally, in a green sheet for ceramic multilayer wiring, two or more kinds of ceramic powder such as mullite and alumina are used, and a large amount of ceramic powder and a small amount of ceramic powder are mixed. , Uniform mixing, uniform kneading is required. In the above method of mixing and kneading raw materials with a conventional ball mill,
Solvent, ceramic powder, binder, dispersant, etc. are put into the device all at once and uniformly mixed over a long period of time, that is, a small amount of ceramic powder is uniformly mixed in a large amount of ceramic powder and kneading (uniform dispersion) is performed. , A slurry was prepared.

However, in the case of continuously producing the slurry, as in the above-mentioned ball mill mixing method,
In the charging procedure in which the raw materials are charged all at once, there is a problem in that it is not possible to manufacture a slurry that is uniformly mixed and uniformly dispersed. Therefore, when continuously producing a slurry, it was necessary to find a charging procedure suitable for the apparatus.

An object of the present invention is to make it possible to uniformly mix and uniformly disperse a slurry that is continuously supplied in a slurry manufacturing apparatus that continuously performs mixing, kneading and defoaming of the slurry. It is to provide a method for manufacturing a slurry for green sheets.

[0006]

According to the present invention, raw materials composed of two or more kinds of ceramic powder, solvent, dispersant and binder are roughly mixed, kneaded and defoamed to produce a green sheet slurry. In the method, a solvent, a first ceramic powder with a small amount, a second ceramic powder with a large amount, a dispersant, and a binder are charged in this order as raw materials into a rough mixing tank for roughly mixing the raw materials. A method for producing a slurry for a green sheet is provided.

Further, according to the present invention, in a method for producing a slurry for a green sheet by roughly mixing raw materials composed of two or more kinds of ceramic powder, a solvent, a dispersant and a binder, and kneading and defoaming the raw materials, A solvent and a dispersant are put into a rough mixing tank for roughly mixing to prepare a mixed solution, and two or more kinds of ceramic powders which have been uniformly dry-mixed in advance are put into the mixed solution, and then a binder is added. A method for producing a green sheet slurry is provided.

The two or more types of ceramic powders used in the method for producing a slurry of the present invention have a large amount of components.
The main component is mullite and the like, and the trace amount component is alumina and the like as a sintering aid. The large amount of components occupies about 99 to 90% by volume of the whole ceramic powder, and the small amount of components is about 1 to 10% by volume of the whole ceramic powder.

The present invention will be described below with reference to the drawings.
FIG. 1 shows the configuration of a continuous kneading and defoaming apparatus for carrying out the present invention, which continuously performs mixing, kneading and defoaming.

The continuous kneading / defoaming apparatus shown in FIG. 1 is configured such that a ceramic powder, a solvent, a binder, etc. are charged and stirred and mixed to prepare a slurry, and a slurry prepared in the crude mixing tank 5 is primarily used. A cushion tank 6 for storing and quantitatively sending the slurry to the next step, a kneading and dispersing device 7 including a multiple sand mill for kneading and dispersing the slurry sent from the cushion tank 6, and a viscosity adjustment of the slurry The defoaming tank 8 is provided. The slurry continuously discharged from the defoaming tank 8 is stored in the dam tank 10 of the casting machine.

2 and 3 are process charts illustrating a method for producing a slurry according to the present invention.

When the present invention is carried out in the step of FIG. 2 using the apparatus of FIG. 1, the solvent is supplied from the solvent supply tank 2 to the pump 3
After being charged into the rough mixing tank 5 by using, the stirring blade 9 is rotated and while the solvent is being stirred, a small amount of ceramic powder is added and mixed from the charging port 4 to dissolve the agglomerates and to disperse the primary particles (ceramics). The original form of powder particles). Then, a large amount of ceramic powder is added from the powder feeding hopper 1 and sufficiently mixed so that a small amount of ceramic powder is uniformly mixed in the large amount of ceramic powder. The dispersant is added and mixed from the charging port 4 in order to further improve the dispersibility of the ceramic powder.
However, when the ceramic powder is added before and after the dispersant is added, the dispersant adheres to all the surfaces of the particles of the ceramic powder added earlier, and when mixed with the ceramic powder added later, sufficient dispersibility is obtained. I can't. For this reason,
In the case of step, after mixing all the ceramic powders,
It is important to add a dispersant. After the dispersant is added, stirring and mixing are further performed to make the ceramic powder into primary particles. After that, a binder is added from the charging port 4, and the mixture is stirred and mixed to obtain a slurry in which the binder is attached to the surface of the ceramic powder that has become primary particles.

In the case of the process shown in FIG. 2, even when there are three or more kinds of ceramic powders, the principle is to put in a small amount first and a large amount later. That is, the ceramic powder with the smallest amount is added in order. However, for example, in the case of a small amount of two types and a large amount of one type, and when the small amounts of the two types have a small difference in amount, any of the small amounts may be given first.

When the present invention is carried out in the step of FIG. 3 using the apparatus of FIG. 1, first, a solvent is supplied from the solvent supply tank 2 to the rough mixing tank 5 by using the pump 3, and then the stirring blade 9 is used. While the solvent is being stirred and the solvent is being stirred, a dispersant is added from the charging port 4 and mixed to prepare a mixed solution of the solvent and the dispersant. If one kind of ceramic powder is added to this mixed solution, sufficient dispersibility cannot be obtained. Therefore, two or more kinds of ceramic powders are dry-mixed in advance to prepare a uniformly mixed ceramic powder. It is put in the powder feeding hopper 1, added to the mixed liquid of the solvent and the dispersant, and stirred and mixed. Then, a binder is added from the charging port 4 and mixed to obtain a slurry.

In the case of the process of FIG. 3, since two or more kinds of ceramic powders are dry-mixed in advance, the same process can be performed regardless of the kind of ceramic powders.

[0016]

In the ceramic powder, particles of the powder are usually adhered to each other and are larger than the particle size of the original single particle. In the process of FIG. After adding a small amount of ceramic powder to the mixture to break up the agglomerates and disintegrating it into single particles, add a large amount of ceramic powder, and mix the small amount of ceramic powder into a large amount of ceramic powder so that it is evenly mixed. Mix. afterwards,
Since the binder is added after the dispersant is added to further improve the dispersibility, a slurry in which the binder is attached to the surfaces of the primary particles of the ceramic powder can be obtained.

Further, in the process of FIG. 3 of the present invention, a small amount of ceramic powder and a large amount of ceramic powder are dry-mixed beforehand to prepare a uniformly mixed ceramic powder, which is put into the coarse mixing device. Put in the mixed solution of the solvent and the dispersant. Therefore, by mixing the ceramic powder in the solution of the dispersant diluted with the solvent, the dispersant is evenly distributed in the ceramic powder and the dispersibility is improved. After that, since the binder is added, the slurry in which the binder is adhered to the surface of the primary particles of the ceramic powder is obtained in this case as well.

[0018]

EXAMPLES Examples of the present invention will be described below.

Example 1 A slurry for a green sheet of a ceramic multilayer wiring board was manufactured in the process of FIG. 2 using the apparatus of FIG. As a large amount of ceramic powder and a small amount of ceramic powder, mullite powder with an average particle size of about 3.0 μm and alumina powder with an average particle size of about 0.6 μm are used in a volume ratio of 9
Used at 5: 5.

First, pure water as a solvent is charged from the solvent supply tank 2 into the rough mixing tank 5 by using the pump 3, and the stirring blade 9 is rotated to stir the solvent while the charging port 4 is introduced.
Then, alumina powder is added and mixed by stirring to release the agglomeration of the alumina powder to form primary particles, and then the powder feeding hopper 1
From the above, mullite powder is added and sufficiently mixed so that a small amount of alumina powder is uniformly mixed in a large amount of mullite powder.

Next, a surfactant was added as a dispersant from the charging port 4 and the mixture was stirred and mixed. Then, an acrylic resin was charged as a binder from the charging port 4 and the mixture was stirred and mixed. This slurry is sent to the cushion tank 6,
From the above, the slurry was quantitatively sent to the kneading and dispersing device 7 to be kneaded and dispersed, and then the viscosity of the slurry was adjusted in the defoaming tank 8.

The slurry mixed in the rough mixing tank 5 is
After all the materials have been sent to the cushion tank 6, the raw materials are again charged into the rough mixing tank 5 by the same charging procedure as described above, and the mixture is stirred and mixed to produce a slurry. Defoaming could be carried out continuously.

The slurry continuously sent from the defoaming tank 8 to the casting machine is stored in the dam tank 10 of the casting machine, and is driven by a doctor blade at a constant speed at the discharge pressure of the defoaming tank on a conveyor. When it was discharged onto a film and dried while being stretched to produce a green sheet, the particles were well adhered to each other via a binder attached to the surface of the primary particles, and when the sheet was formed, it was difficult to break, It was excellent in tackiness.

Example 2 Using the apparatus shown in FIG. 1, a slurry for a green sheet for a ceramic multilayer wiring board was manufactured in the step shown in FIG. Mullite powder with an average particle size of about 3.0 μm and alumina powder with an average particle size of about 0.6 μm are used in a volume ratio of 9
The mixture was preliminarily dry mixed at 5: 5 to prepare a uniformly mixed ceramic powder.

Pure water as a solvent is supplied from the solvent supply tank 2.
Put into the rough mixing tank 5 using the pump 3, and stir the blade 9
While stirring the solvent by rotating the,
A surfactant was added as a dispersant and mixed by stirring to obtain a mixed solution of a solvent and a dispersant. The above-mentioned homogeneously mixed ceramic powder was put into the powder feeding hopper 1 and added to the mixed liquid in the rough mixing tank 5 to carry out stirring and mixing. After that, add acrylic resin as a binder from the charging port 4,
Further, stirring and mixing were carried out to obtain a slurry in which the binder was attached to the surfaces of the ceramic particles. This slurry was sent to the cushion tank 6, the slurry was quantitatively sent from the cushion tank 6 to the kneading and dispersing device 7 to be kneaded and dispersed, and then the viscosity of the slurry was adjusted in the defoaming tank 8.

After all the slurry mixed in the rough mixing tank 5 is sent to the cushion tank 6, the raw materials are again charged into the rough mixing tank 5 by the same charging procedure as above, and the mixture is stirred and mixed to produce a slurry. By sending it to the cushion tank 6, subsequent kneading and defoaming could be continuously performed.

A green sheet was prepared from the slurry taken out of the defoaming tank 8 in the same manner as in Example 1, and the particles were well bonded to each other via the binder attached to the surface of the primary particles. The sheet was not easily broken when formed into a sheet, and the sheet had excellent tackiness.

[0028]

According to the present invention, in an apparatus for continuously producing a slurry, two or more kinds of ceramic powders can be uniformly mixed in a rough mixing tank, and a slurry of stable quality can be continuously produced. It can be manufactured.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a continuous kneading and defoaming apparatus for carrying out the present invention, which continuously performs mixing, kneading, and defoaming.

FIG. 2 is a process drawing of an example of a method for producing a slurry according to the present invention.

FIG. 3 is a process drawing of another example of the method for producing a slurry according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Powder charging hopper, 2 ... Solvent supply tank, 3 ... Pump, 4 ... Input port, 5 ... Rough mixing tank, 6 ... Cushion tank, 7 ... Kneading dispersion device, 8 ... Defoaming tank, 9 ... Stirring blade, 10 ... Dam tank of casting machine.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroshi Hasegawa 1 Horiyamashita, Hadano City, Kanagawa Pref., General Computer Division, Hitachi, Ltd. (72) Masayuki Kawarada 1 Horiyamashita, Hadano, Kanagawa Prefecture Factory General Computer Division

Claims (6)

[Claims] 1. A method for roughly mixing raw materials consisting of two or more kinds of ceramic powder, a solvent, a dispersant and a binder, kneading and defoaming to produce a slurry for a green sheet. In the tank, solvent, a small amount of the first ceramic powder, a large amount of the second ceramic powder,
A method for producing a slurry for a green sheet, which comprises adding a dispersant and a binder as raw materials in this order. 2. The method for producing a green sheet slurry according to claim 1, wherein kneading and defoaming are continuously performed. 3. The method for producing a slurry for a green sheet according to claim 1, wherein the two or more kinds of ceramic powders are composed of a ceramic powder as a main component and a sintering aid added thereto. 4. A method for producing a slurry for a green sheet by roughly mixing raw materials composed of two or more kinds of ceramic powder, a solvent, a dispersant and a binder, and kneading and defoaming to produce a slurry for a green sheet. A green characterized in that a solvent and a dispersant are put into a tank to prepare a mixed solution, and two or more kinds of ceramic powders which have been uniformly dry mixed in advance are put into the mixed solution, and then a binder is put therein. A method for producing a slurry for a sheet. 5. The method for producing a green sheet slurry according to claim 4, wherein kneading and defoaming are continuously performed. 6. The method for producing a green sheet slurry according to claim 4, wherein the two or more kinds of ceramic powders are composed of a ceramic powder as a main component and a sintering aid added thereto.