JPS60228109A - Manufacture of sludge for ceramic dielectric - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Technical field to which the invention pertains) The present invention relates to a method for producing ceramic dielectric green sheets (hereinafter referred to as "green sheets") that have a stable firing shrinkage rate when mixing and improving the yield. The present invention relates to a method for producing a dielectric slurry (hereinafter referred to as slip).

(Prior art and its problems) Generally, green sheets are made of ceramic dielectric raw material powder such as barium titanate as a binder and plasticizer.

It is produced by dispersing it in a vehicle consisting of a solvent and a dispersant to form a slip, casting it onto a polyester film, and drying the solvent. On the other hand, a ceramic dielectric is made by punching a green sheet into a predetermined shape and then firing it, and the dimensions of the dielectric are determined by the shrinkage rate during firing. Therefore, in order to improve dimensional accuracy, the firing shrinkage rate must always be kept constant. Also, there is a correlation between the firing shrinkage rate and the bulk density of the green sheet, and keeping the bulk density of the green sheet, that is, the packing rate (filling rate) of the ceramic dielectric raw material powder particles constant, keeps the firing shrinkage rate constant. It is important to

Conventionally, ceramic dielectric raw material powder and binder were used.

The plasticizer, solvent, etc. are put together in a ball mill mixer and mixed all at once. However, with this mixing method, the viscosity of the slip is high, so the particles of the agglomerated ceramic dielectric raw material powder cannot be disintegrated into single particles, and the binder, plasticizer, etc. are not well dispersed throughout the particles, resulting in variations in the bulk density of the green sheet. It is the cause. There is also a method in which the ceramic dielectric raw material powder is predispersed in a solvent (first step) and then a binder, plasticizer, etc. are added (second step), but with this method, pseudo-agglomeration is likely to occur in the first step. . Therefore, if a ball mill is continuously and repeatedly used in this manner, the firing shrinkage rate of the green sheet will vary.

OBJECTS OF THE INVENTION The object of the invention is to provide a method for producing slips that does not have the above-mentioned disadvantages.

(Means for Solving the Problems) As a result of various studies on the above-mentioned drawbacks, the present inventors found that the viscosity of a solution prepared by adding a binder and a plasticizer to a solvent is below a level that does not hinder the disintegration of ceramic dielectric raw material powder. A binder and a plasticizer are added in an amount that prevents direct contact between the disintegrated particles, and the ceramic dielectric raw material powder is disintegrated into single particles. By adding and mixing slips with the necessary amounts of binder and plasticizer to impart the necessary sheet properties, variations in the bulk density of green sheets can be reduced.
It was also confirmed that slips with little variation in firing shrinkage of green sheets could be obtained even if the ball mill was used repeatedly.

The present invention provides a slip manufacturing method in which a mixture of a ceramic dielectric raw material powder, a solvent, a binder, and a plasticizer are mixed in a container, in which the viscosity of a solution in which the binder and plasticizer are added to the solvent causes the disintegration of the ceramic dielectric raw material powder. A binder and a plasticizer are added and mixed in an amount that is below the level that does not interfere with the process and that prevents the disintegrated particles from coming into direct contact with each other, and the ceramic dielectric raw material powder is disintegrated into single particles.

Then add the amount of binder and plasticizer necessary to give the sheet properties necessary for tape forming and punching,
The present invention relates to a method for producing a mixing slip.

(Material Example) In the present invention, the ceramic dielectric raw material powder is not particularly limited, and for example, barium titanate to which one or more of titanate, stannate, zirconate, etc. is added is used. As the binder, polyvinyl butyral, acrylic resin, vinyl acetate copolymer, polyvinyl alcohol, vinyl chloride, methacrylate, etc. are used.

As the plasticizer, heptatarate esters such as DOP and DBP, and glycol esters such as triethylene glycol and polyalkylene glycol are used. Trichlorethylene, butanol, ethyl alcohol, methyl alcohol, etc. are used as the solvent.

The viscosity of the solution obtained by adding the binder and plasticizer to the solvent is preferably 20 P (voids) at maximum.

It is more preferable if it is in the range of IP to 3P. In addition, the amount of binder and plasticizer added is 1 part of ceramic dielectric raw material powder.
It is preferable that the binder is 0.5 to 20 parts by weight and the plasticizer is 0.25 to 1.0 parts by weight, and the binder is 0.8 to 1.8 parts by weight and the plasticizer is 0.4 to 0.0 parts by weight. More preferably, the amount is 9 parts by weight.

Regarding the amount of binder and plasticizer added to provide sheet properties necessary for tape forming and punching, ceramic dielectric raw material powder 1o.

It is preferable that the binder is 3.0 to 6.6 parts by weight and the plasticizer is 1.5 to 3.3 parts by weight, and the binder is 4.0 to 5.6 parts by weight and the plasticizer is 2.0 to 2 parts by weight. More preferably, the amount is .8 parts by weight.

(Example) The present invention will be explained below with reference to Examples.

In the first step, the ingredients shown in Table 1 were blended and mixed in a ball mill for 30 hours to fully disintegrate barium titanate into single particles, and a uniform coating was formed on the surface of the disintegrated single particles.

Table 1 (margin) Next, as a second step, 4.8 parts by weight of polyvinyl butyral and 24 parts by weight of phthalate were added to the mixture obtained above and mixed for 244 hours to obtain a slip. Then slip the ball onto the inner wall of the mill.

Leave 20% in the ball mill as a part to adhere to cobblestones, etc.

A first green sheet was obtained using 80% of the residue by a commonly known method.

Next, to obtain a second green sheet, 32.0 parts by weight of an azeotropic mixture of trichlorethylene and methanol was added to 28.36 parts by weight of the remaining slip in the ball mill, and the mixture was mixed for 1 hour, and then the same process as above was carried out. 80 parts by weight of barium titanate were added.

The barium titanate was mixed for 300 hours to disintegrate into single particles, and a uniform coating was formed on the surface of the disintegrated single particles.

Next, add polyvinyl butyral 48 to the mixture obtained above.
．． 0 parts by weight and 24.0 parts by weight of phthalate ester were added and mixed for 244 hours to obtain a second slip. After that, 20 pieces of slip were left in the ball mill as a part of the slip to adhere to the inner wall of the ball mill, cobblestones, etc.

A second green sheet was obtained using 80 inches by a commonly known method.

Thereafter, third and fourth green sheets were obtained in the same manner as above.

The green sheet obtained in the above example was heated to a temperature of 1.40.
It was baked at 0°C for 1 hour. As a result, the firing shrinkage was 25.50 inches for the first time, 25.52 inches for the second time, 25.51% for the third time, and 25.55 inches for the fourth time, and the ball mill was used continuously. Despite this, it was confirmed that there was little variation.

On the other hand, as a comparative example, barium titanate was pre-dispersed in a dispersant and a solvent, and then a binder and a plasticizer were added.The green sheet was then mixed from the slip with the remaining slip remaining. As a result, the firing shrinkage was 27.25 inches for the first time, 24.80 inches for the second time, and 24.80 inches for the second time.
The third time was 26.52 inches, and the fourth time was 24.10 inches, which varied widely.

Although the embodiments of the present invention have been described using a ball mill, similar effects can be obtained by using a crusher or other mixing method.

(Effects of the Invention) The present invention provides a solution in which a binder and a plasticizer are added to a solvent in such an amount that the viscosity of the solution is below a level that does not prevent disintegration of the ceramic dielectric raw material powder and prevents disintegrated particles from coming into direct contact with each other. Add and mix the amount of binder and plasticizer necessary to pulverize the ceramic raw powder into single particles and then impart the sheet properties necessary for tape forming and notching. Add, - mix.

It is possible to produce a slip with little variation in the bulk density of the green sheet, and also with little variation in the firing shrinkage rate of the green sheet even if a mixer such as a ball mill is continuously and repeatedly used.

Continuation of page 1 0 shots Akira Kamiyama Mamoru Hitachi City Higashimachi 4th Institute

Claims (1)

[Claims] 1. In a method for producing slurry for ceramic dielectrics, which involves mixing a mixture of ceramic dielectric raw material powder, a solvent, a binder, and a plasticizer in a container, the viscosity of the solution obtained by adding the binder and plasticizer to the solvent is that of the ceramic dielectric raw material powder. The ceramic dielectric raw material powder is granulated until it becomes a single particle by adding and mixing binder and plasticizer in an amount that is below the level that does not interfere with the granulation of the particles and that prevents the granulated particles from coming into direct contact with each other. 1. A method for producing a slurry for ceramic dielectrics, which comprises: (1) adding and mixing a binder and a plasticizer in amounts necessary to impart sheet properties necessary for tape forming and punching;