JPH02208371A - Preparation of ceramic screen ink - Google Patents

Abstract

PURPOSE:To improve the extent of kneading by dispersing a calcined ceramic powder, a resin and a solvent, filtering the resulting dispersion, mixing the resulting filtrate with the resin, and kneading the mixture. CONSTITUTION:100 pts.wt. calcined ceramic powder (e.g. barium titanate) is mixed with 10-60 pts.wt. solvent and 0.1-2 pts.wt. resin (e.g. butyral resin) and dispersed using a dispersing machine with rotating or vibrating balls of 0.5-5mm in diameter. The resulting dispersion is filtered through a membrane filter of about 5mum in thickness to give a filtrate, which is mixed with a resin (e.g. butyral resin) to adjust the viscosity to 100-10000P and then kneaded using a ceramic three-roll mill to give an ink.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to multilayer ceramic capacitors widely used in electrical products such as video tape recorders and liquid crystal televisions.
Multilayer ceramic substrate, varistor.

The present invention relates to a method for producing ceramic screen ink used in producing ceramic electronic components such as piezoelectric elements and thick film capacitors by screen printing.

BACKGROUND OF THE INVENTION In recent years, in the field of electronic components, as circuit boards have become more dense, ceramic electronic components have been manufactured using high-precision screen printing methods.

First, a method for producing screen ink will be briefly explained. The method for manufacturing screen ink used in screen printing for ordinary commercial printing (poster printing, etc.) involves dispersing a specified pigment powder in a vehicle by shearing using a three-roll roll, etc. It is manufactured as a screen ink (called screen ink).

In addition, ceramic screen ink used in the manufacture of various ceramic electronic components is manufactured as ceramic screen ink by dispersing ceramic powder in a vehicle by shearing using a three-roller or the like, in the same way as the general screen ink mentioned above. (hereinafter referred to as the conventional manufacturing method).

However, for ceramic screen ink, 3.
＼-7 Compared to general screen inks, very advanced ink properties are required. Particularly required properties from the ink side include the degree of kneading of the ink. Note that the degree of kneading here refers to the degree of dispersion when the powder is loosened, thoroughly kneaded with the vehicle, and finely dispersed in the vehicle when the powder and vehicle are made into ink using a kneading machine. This is one means of evaluation, and is defined in JIS (K-5701) to be evaluated using a grindmeter. It is generally known that the degree of kneading can be increased by decomposing (or dispersing) secondary particles of powder in ink into primary particles.

It has been known that when ceramic electronic components are manufactured using ceramic screen ink with poor kneading (many secondary particles, poor dispersion), the reliability of the finished ceramic electronic components is poor. . In other words, if the degree of mixing of the ceramic screen ink is poor (there are uneven lumps in the ceramic screen ink), voids (holes) etc. will be generated inside the ceramic electronic components.
This impairs reliability. Therefore, in order to manufacture highly reliable and highly accurate ceramic electronic components, it is essential to manufacture ceramic screen ink that has a higher kneading degree than general screen ink.

Generally, ceramic powder contains a large number of secondary particles that are strongly bonded (agglomerated) by being calcined. When a ceramic powder containing a large number of such strongly bonded secondary particles is made into an ink using a conventional manufacturing method using a three-roll mill, it is not possible to increase the degree of kneading of the ink. In other words, this is considered to be because there was a limit to the ability to decompose these strongly bonded secondary particles into primary particles. This is because it is difficult to obtain the ability to disperse these strong secondary particles down to the primary particles with the level of shear produced by a three-roll mill, and also because when the shear conditions are strengthened in a three-roll mill, the secondary particles are Before dispersing in particle size, the resin contained in the vehicle must be physically destroyed (
This is because there is a problem that the resulting ink may have a change in its physical properties (such as a decrease in viscosity) due to a decrease in the molecular weight (such as a decrease in molecular weight).

For this reason, wet methods are widely used for dispersing ceramic powders containing such strong secondary particles. Here, the wet method is a method in which ceramic powder is dispersed together with a predetermined solvent and resin using a ball mill for several hours to several tens of hours. However, such a dispersion method using a ball mill cannot produce a highly viscous product. This is because when attempting to disperse a highly viscous ceramic ink using a ball mill, the balls cannot move due to their high viscosity and end up adhering to the inner wall of the ball mill, etc. For this reason, it is usually difficult to manufacture ceramic ink with a size of about 30 poise or more using a dispersion machine using balls, and ceramic ink with a size of 10 poise or less is usually manufactured using a dispersion machine using balls such as a ball mill. There is. On the other hand, when normally used as a screen ink, if the viscosity is too low, it will ooze out from the screen, so if the viscosity is above a certain level (approximately 1006
−.

poise or more, preferably about 500 poise). As described above, the wet method using Shibor can only produce ink with a low viscosity, and the slurry produced in this way cannot be used for screen printing.

It has also been proposed to disperse ceramic powder in a solvent using a ball mill and then add resin. However, when producing ceramic ink using a ball mill after adding resin, the resin may stop moving due to the thickening effect of the resin, so there is a limit to the amount of resin that can be added.

Problems to be Solved by the Invention In the method for manufacturing such surface ceramic screen ink, a ball mill could not be used because the viscosity was too high. Furthermore, the ceramic powder could not be sufficiently dispersed in the production method using a three-roll mill, which is commonly used in the production method of screen ink.

In view of such problems, an object of the present invention is to manufacture an excellent ceramic screen ink with a high degree of kneading.

Means for Solving the Problem In order to solve this problem, the present invention provides at least 10 parts by weight of a solvent for 100 parts by weight of calcined ceramic powder.
0 parts by weight or less, add 0.1 parts by weight or more and 2 parts by weight or less of resin, disperse with a dispersing machine using a rotating or vibrating ball, filter, add resin to this filtrate, and reduce the viscosity. 10
The present invention provides a method for producing a ceramic screen ink, which comprises reducing the ink to 0 poise or less and 210,000 poise or less, and then kneading it using a three-roll mill.

Effect With this configuration, when dispersing ceramic powder in a solvent using a ball mill, by adding resin as a kind of dispersant, the concentration of ceramic powder can be set high, and the contamination of impurities, which can be a problem with ceramics, can be prevented. The ceramic powder is first dispersed in the form of primary particles in a solvent, and then a resin is added to increase the viscosity from 100 poise to 1000 poise. By doing the following, the degree of kneading of the ink can be effectively increased by dispersing the ceramic powder by the shearing motion of the three-roll mill.

t, b. In the method for producing ceramic screen ink of the present invention, dispersion of fine ceramic powder secondary particles to primary particles is achieved by controlling the amount of resin added to 0.1 parts by weight or more and 2 parts by weight or less. While preventing the increase in viscosity caused by the addition of the resin, the effect of dispersing the ceramic powder by adding the resin can be obtained. By creating a dispersion system with a low viscosity in this way, secondary particles are effectively pulverized, and the resin has a viscosity (usually 100 poise or more) for screen ink.
1. By increasing the viscosity in this way and stabilizing the dispersed primary particles in the resin without drying them, it is possible to create a ceramic screen ink with a high degree of kneading. It manufactures.

In other words, when dispersing in a low viscosity state, the low viscosity makes it possible to effectively use a dispersion machine that uses POL, and after effectively destroying the secondary particles formed by calcining the ceramic particles down to the primary particles. By filtering, adding a resin to the filtrate to make it have a predetermined viscosity, and kneading it using a three-roll mill, it is possible to increase the degree of kneading of the ink without changing the molecular weight of the resin.

EXAMPLES The method for producing ceramic screen ink of the present invention will be described below.

First, a ceramic screen ink manufactured by the manufacturing method of the present invention (hereinafter simply referred to as the method of the present invention) and a ceramic screen ink manufactured by a conventional method (hereinafter simply referred to as the conventional method) were manufactured and compared.

First, the ceramic screen ink of the present invention was manufactured as follows. First, 38 parts by weight of a solvent, 1 part by weight of butyral resin, and 50 parts by weight of 2-diameter zirconia balls were added to 100 parts by weight of dielectric plate powder containing barium titanate as the main component, and the mixture was heated using a vibrating ball mill. about 6
The mixture was dispersed for a period of time to form a slurry. Here, the viscosity of the slurry was measured using a double cylindrical nozzle meter constructed using JIS standard viscosity liquid at a measurement temperature of 26°C2 in a shear rate range of 10.
~500 (17 seconds), it was about 2 poise. Here, the amount of butyral resin added to 100 parts by weight of dielectric plate baked powder was varied from 0 parts by weight to 20 parts by weight, but when the amount added was 0 to 0.2 parts by weight, the slurry had chicken-tropic properties (powder The viscosity was 100 poise or more (in the low slip rate range) due to viscosity changes due to manufacturing viscosity due to agglomeration, etc.

Furthermore, when the amount added exceeded 2 parts by weight, the viscosity increased in proportion to the amount added. Further, when the amount added is 0.1 to 2 parts by weight (particularly around 1 part by weight), the chicken tropism was small, and even in a low speed range, the viscosity was able to reach the minimum value of about 2 poise. Next, when the degree of dispersion (degree of kneading) was evaluated using a grind meter, it was found that even elementary particles were dispersed, with a diameter of about 2 μm or less. The method for evaluating the degree of dispersion is based on the grind meter defined in JIS (K-rsryo01) (for 0 to 10 μm).
We decided to create and use this to evaluate the degree of familiarity.
At the same time, the dielectric calcined powder was measured using a commercially available laser particle size analyzer, and the average particle size was 1.
It was 2 microns.

Next, the zirconia beads were removed from this slurry, and the slurry was filtered. Here, as a filter, a Fre filter and a membrane filter with a pore size of 10 microns were used to perform pressure filtration to obtain a filtrate. Next, butyral resin was added to this filtrate until it reached about 500 poise, and then it was made into an ink (hereinafter simply referred to as invention ink) using a ceramic Miki roll mill.

For comparison, the previously calcined barium titanate powder was made into screen ink using the conventional method.

First, a vehicle consisting of butyral resin, additives, and solvent in an amount corresponding to the inventive ink is manufactured, and then the above-mentioned calcined powder is added in an amount equivalent to the inventive ink, and an ink is formed using a three-roll mill (
Hereinafter, it will be simply referred to as conventional ink (■).

Furthermore, for comparison, pure water was added to the calcined powder and dispersed for 100 hours using a ball mill.
The ink was evaporated in a dryer heated to 50"C and turned into ink using a three-roll mill (hereinafter simply referred to as conventional ink).
).

Next, Table 1 below shows the ink kneading time (inking time) for each ink using three rolls and the results regarding the ink kneading dust at that time.

<Table 1> The results in Table 1 show that the inventive ink can improve the mixing dust in a short time compared to the conventional ink. With the conventional ink (2), the result was that the secondary particles contained in the fired powder could not be sufficiently decomposed into primary particles by dispersion using only a three-roll mill. In addition, in conventional ink (2), secondary particles that are relatively difficult to decompose are formed when pure water is evaporated after pulverizing the fired powder using a wet method using a primary particle mill. In addition, an attempt was made to filter conventional ink (1) and conventional ink (2) using the membrane filter, but the filtering was not possible. This is because the mixing dust of these inks is not sufficient.

In particular, in the present method for producing ceramic screen ink, the viscosity at the time of filtration can be made extremely low because no resin is added, so that filtration can be easily performed.

In this example, three ceramic rolls were used. This is because when three metal rolls are used, the metal on the roll surface is scraped by the ceramic powder when kneading the ceramic powder, and as a result, it is mixed into the ink as impurities. be.

The dispersing machine used for producing the ceramic screen ink may be one that uses a ball, and a rotary ball such as a ball mill or a sand mill, or a vibrating ball may also be used.

In addition, when decomposing the secondary particles contained in the calcined powder to primary particles 14\, the diameter of the ball is 0.5 to 5 mπ.
It was effective to a certain extent.

In addition, the amount of solvent added to the ceramic powder must be less than 10 parts by weight per 100 parts by weight of the ceramic powder, otherwise even if additives are added, the surface of the ceramic powder will be completely wetted with the solvent, making it difficult to disperse using a ball mill. Since it is not possible to provide the necessary fluidity, dispersion using balls cannot be performed efficiently.

In addition, 60 parts by weight of the solvent was added to 100 parts by weight of the ceramic powder.
If the amount exceeds parts by weight, the ceramic powder concentration may be low.
Dispersion becomes less efficient.

Also, when kneading ink using a three-roll mill,
If the viscosity is less than 100 poise, the kneading effect by shearing in the three-roll mill will be poor, while if it exceeds 10,000 poise, the viscosity will become too high and the ink will slip on the surface of the three-roll mill during kneading. The kneading effect worsens.

In addition, the amount of resin added is effective when it is 0.1 parts by weight or more, especially from 0.5 to 100 parts by weight of ceramic powder.
It was effective at 1M parts. Also, if more than 5 parts of resin is added, the viscosity due to the resin will increase.
Since secondary rise occurs, the dispersion effect by beads is reduced. - If a dispersant is included when sintering ceramic electronic parts made using ceramic ink for boat fishing, the sinterability or electrical properties may deteriorate depending on the amount of dispersant added. Are known. In the present invention, by adding an appropriate amount of a binder resin used as a binder resin for ordinary ceramic electronic components, it can be used as a dispersant, and as a result, the sinterability or electrical properties will not be degraded. . Furthermore, even when a dispersant is added, as explained in the present invention, the addition of an appropriate amount of resin enhances the dispersion effect, making it possible to reduce the amount of the dispersant added compared to the conventional method. It is possible to solve problems such as

In addition to butyral resin, resins that can be used for this purpose include cellulose resins such as ethyl cellulose and methyl cellulose, alcohol resins such as polyvinyl alcohol, or resins such as acrylic resin and rosin resin. can.

Furthermore, the ceramic screen ink produced by this manufacturing method can be easily filtered by dispersing it using a ball and then filtering it using a 571 m membrane filter (using a pre-filter if necessary). It was possible to produce a ceramic screen ink from which residual particles with a particle size of 5 μm or more were completely removed. In this way, it is possible to easily produce a ceramic screen ink composed of particles having a desired particle size or less.

Furthermore, especially in ceramic screen inks used in the manufacture of electronic components, the particle size design of the ceramic powder contained therein is an important factor in increasing the filling rate (clogging degree) of the dry ink film. For this reason, conventionally, ceramic particles of different particle sizes and sizes are mixed in a powder state and then formed into ink. However, according to this manufacturing method, ceramic powders with different particle sizes are dispersed using a dispersion machine using a ball, and then filtered.
＼ Then, by mixing this filtrate, it is in a dispersed state! ,
It is also possible to produce a ceramic screen ink consisting of particles of different particle sizes. In this way, the ink properties, electrical properties, filling rate, etc. of the ceramic powder contained in the ceramic screen can be further improved.

Effects of the Invention As described above, the present invention provides calcined ceramic powder,
By using a rotating or vibrating ball in a solvent and dispersing it in a low viscosity state with a dispersion device, secondary particles can be easily destroyed down to the primary particles, and it can also be easily filtered. By adding a predetermined amount of resin and kneading the ink using a three-roll mill, it is possible to easily produce a highly kneaded ceramic screen ink.

Claims (1)

[Claims] To 100 parts by weight of the calcined ceramic powder, add 10 parts by weight to 60 parts by weight of a solvent and 0.1 parts by weight to 2 parts by weight of a resin, and use a dispersion machine using a rotating or vibrating ball. A method for producing a ceramic screen ink, which comprises dispersing, filtering, adding a resin to the filtrate, adjusting the viscosity to 100 poise or more and 10,000 poise or less, and then kneading using a three-roll mill.