JPH09169569A - Ceramic molding composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a ceramic molding compsn. fit for a ceramic green sheet having >=3MPa sheet strength, excellent also in flexibility and adhesion, easy to handle, not causing defects such as cracks by post-working and satisfying reduced thickness and increased size as recent requirements. SOLUTION: This compsn. is a mixture prepd. by adding at least an acrylic additive as a binder, a plasticizer and a solvent to powdery oxide or nonoxide ceramic stock. The plasticizer is at least (iso)phthalic ester having >45 to <70 deg.C m.p. and the amt. of the (iso)phthalic ester is 2-6wt.% of the amt. of the ceramics stock.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic molding composition suitable for molding a ceramic green sheet applied to a ceramic multilayer substrate or various ceramic laminated electronic parts.

[0002]

2. Description of the Related Art Conventionally, as a method for molding a ceramic product, a press molding method using ceramic granules, a doctor blade method or a casting molding method using ceramic sludge, an extrusion molding method using a clay, an injection molding method. Have been put into practical use.

Among them, the doctor blade method, which is widely used as a method for forming a ceramic green sheet, mixes and stirs a ceramic raw material powder and an organic additive and a binder composed of a plasticizer, an organic solvent, etc. with a mixing machine such as a ball mill. The slurry is made into a sludge, and the sludge is formed into a sheet with a uniform thickness on a film, and the sheet-shaped compact is continuously dried to produce a ceramic green sheet.

Generally, polyvinyl butyral (P) is used as an organic additive mixed with the ceramic raw material powder.
VB), acrylic resin and the like, and cheap plasticizers such as dibutyl phthalate (DBP) and dioctyl phthalate (DOP) are used. By adjusting the combination and blending amount of these, it is necessary as a ceramic green sheet. The obtained sheet strength was about 1 to 2 MPa and the flexibility to withstand punching was obtained.

However, as the organic additive, P
When VB is used, the sheet strength is high, but the thermal decomposability is poor. Therefore, acrylic resins, which have good thermal decomposability, are now the mainstream of organic additives.

[0006] However, although the acrylic resin has improved thermal decomposability, it has a drawback that the sheet strength and flexibility are impaired.

In order to eliminate such drawbacks, an acrylic resin satisfying predetermined conditions such as an average molecular weight, an acid value, a glass transition point and a compatibility with a solvent is used as an organic additive, and a ceramic green sheet is made flexible. It has been proposed to add a plasticizer such as a phthalic acid ester in order to impart the properties (Japanese Patent Application Laid-Open Nos. 6-237054 and 5).
-194019).

[0008]

However, there are polyacrylates and polymethacrylates as the acrylic resins generally available as the organic additives proposed above.
Although these all have good thermal decomposability, the sheet strength of ceramic green sheets is as low as 2-3 MPa at the maximum, and recent ceramic green sheets have higher sheet strength than ever due to their thinner layers and larger sizes. However, there is a problem that the requirements are not satisfied.

Further, if the amount of plasticizer added is reduced to improve the sheet strength, the sheet strength will certainly increase, but on the contrary, the flexibility of the ceramic green sheet will be lost, and it will be In addition to the problem that cracks occur in the sheets, this also causes wear of the punching device, and there is also the problem that thermocompression bonding becomes difficult when laminating the ceramic green sheets.

[0010]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and its purpose is to achieve a sheet strength of more than 3 MPa, excellent flexibility and adhesion, easy handling, and cracking after processing. It is an object of the present invention to provide a ceramic molding composition suitable for a ceramic green sheet that satisfies the recent demands of thin layer and large size without causing defects such as the above.

[0011]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have found that a ceramic raw material powder to which at least an acrylic additive and a solvent are added has a predetermined melting point. It has been found that the above problem can be solved by adding a predetermined amount of phthalic acid ester or isophthalic acid ester as a plasticizer or as a part of the plasticizer.

That is, the ceramic molding composition of the present invention is a mixture prepared by adding at least an acrylic additive, a plasticizer, and a solvent as a binder to an oxide or non-oxide ceramic raw material powder. The plasticizer in the mixture is a phthalic acid ester or an isophthalic acid ester having a melting point in the range of at least 45 ° C. and less than 70 ° C., and the content of the phthalic acid ester or the isophthalic acid ester is in the ceramic raw material powder. On the other hand, it is characterized by being in the range of 2 to 6% by weight.

[0013]

According to the ceramic molding composition of the present invention, a plasticizer having a melting point of more than 45 ° C. and less than 70 ° C. exists as a solid at room temperature. If the sheet strength at room temperature increases and the amount of solid plasticizer is larger than that of liquid plasticizer, the sheet strength is also increased accordingly.

On the other hand, as the strength of the sheet is improved, the flexibility is deteriorated. However, when the ceramic green sheet is heated to a temperature near the melting point of the plasticizer, the solid plasticizer is liquefied to form a sheet. Since it softens, punching of the ceramic green sheet can be easily performed by heating it above the melting point of the plasticizer.

Further, at the time of thermocompression bonding, the ceramic green sheets are heated so that the solid plasticizer is liquefied and exudes between the laminated ceramic green sheets,
Thermocompression bonding is also easy.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION First, a method for preparing a ceramic molding composition of the present invention comprises the steps of adding a predetermined amount of at least an acrylic additive, a plasticizer and a solvent as a binder to an oxide or non-oxide ceramic raw material powder. The mixture is added, and a uniform slurry of the mixture is prepared by a stirring means such as a general ball mill, a vibration mill, a stirrer, or a Henschel mixer.

At this time, the method of adding the ceramic raw material powder and each binder component is not particularly limited, as long as it finally becomes a uniform composition, and if necessary, an antifoaming agent or a defoaming agent is added. Alternatively, the mixture may be sufficiently stirred and then defoamed to prepare a ceramic molding composition.

The ceramic molding composition thus obtained is cast onto a film by a doctor blade method to form a sheet having a predetermined thickness, and then continuously dried to produce a ceramic green sheet.

In the present invention, when the melting point of the plasticizer is 45 ° C. or less, the sheet strength is weak because it is close to room temperature.
At 0 ° C or higher, a large amount of heat is required to heat the sheet to soften the sheet during post-processing such as punching, so the melting point of the solid plasticizer to be added is limited to more than 45 ° C and less than 70 ° C. It

Examples of the plasticizer having a melting point of more than 45 ° C. and less than 70 ° C. include phthalic acid ester, isophthalic acid ester, phosphoric acid ester, benzoic acid ester, citric acid ester, etc. Considering that it has good compatibility with the acrylic resin used, is excellent in thermal decomposition, can be obtained at low cost, and has good compatibility with general plasticizers such as DBP and DOP, phthalic acid ester or isophthalic acid ester. Specified in.

As the phthalic acid ester having the above melting point, dihexyl phthalate, dicyclohexyl phthalate,
Dihydroabietyl phthalate and isophthalic acid ester include dimethyl isophthalate, etc. These can be used alone or in combination, and can also be used in combination with other general plasticizers as plasticizers. .

When an acrylic additive such as ethyl acrylate or 2-ethylhexyl methacrylate, which will be described later, having flexibility even at room temperature is used,
No general plasticizer such as DBP or DOP is added,
Only the predetermined phthalic acid ester or ishiphthalic acid ester may be used.

When the content of the phthalic acid ester or isophthalic acid ester is less than 2% by weight with respect to the ceramic raw material powder, the sheet strength does not increase, and when it exceeds 6% by weight, the flexibility at room temperature becomes low. The content is specified to be 2 to 6% by weight, because the ceramic green sheet is cracked during transportation and the thermal decomposability is deteriorated.

The acrylic additive used in the present invention is preferably an acrylic resin having excellent thermal decomposability,
Methyl (meth) acrylate, ethyl (meth) acrylate, isobutyl (meth) acrylate, 2-ethylhexyl acrylate and the like can be mentioned, and among them, isobutyl methacrylate, which has high strength and is excellent in thermal decomposability, is most suitable.

Considering the sheet strength, the acrylic additive has a low molecular weight when it has a molecular weight of less than 200,000, and has a difficulty in handling when it has a molecular weight of more than 400,000, and has a poor thermal decomposability. 200-400,000 is good, and the addition amount is 8-12 with respect to the ceramic raw material powder.
It is desirable to add in the range of parts by weight.

As a main component of the ceramic raw material powder of the present invention, an insulating substrate such as alumina, mullite, or glassella, an oxide ceramics used as a dielectric such as barium titanate, or nitriding used as a high thermal conductive substrate. It can be applied to any non-oxide ceramics such as aluminum.

Further, the solvent of the present invention may be any solvent as long as it has good wettability with the ceramic raw material powder, is volatile, and is inexpensive, and examples thereof include water, alcohol, and hydrocarbon solvents. .

[0028]

EXAMPLES Hereinafter, the ceramic molding composition of the present invention will be specifically evaluated based on Examples. First, a slurry was prepared as follows by using alumina, aluminum nitride, and barium titanate as main components as a ceramic raw material powder.

With respect to 100 parts by weight of the raw material powder containing alumina as a main component, 10 parts of an acrylic resin was added as an organic additive.
A plasticizer was added to 35 parts by weight of toluene and 35 parts by weight of toluene at a ratio shown in Table 1, and wet mixed for 48 hours in a rotary mill to prepare a slurry.

On the other hand, to 100 parts by weight of the raw material powder containing aluminum nitride as a main component, 12 parts by weight of an acrylic resin as an organic additive and a plasticizer at a ratio shown in Table 1 were added, and a solvent was further added. Add 30 parts by weight and use ball mill 2
Sludge was prepared by tumbling for 0 hours.

Further, to 100 parts by weight of the raw material powder containing barium titanate as a main component, 10 parts by weight of an acrylic resin as an organic additive and a plasticizer were added at a ratio shown in Table 1, and a solvent was further added. Add 30 parts by weight and add 20 on a ball mill.
Slurry was prepared by time-wise mixing.

Next, the sludge is vacuum-extracted to remove the air in the sludge, and a doctor blade method containing alumina and aluminum nitride as main components has a thickness of 250 μm.
A sheet containing barium titanate as a main component was molded into a sheet having a thickness of 30 μm to obtain a ceramic green sheet for evaluation.

The melting point of the plasticizer is JIS-K-0 in which a capillary having an inner diameter of 1.0 mm and a length of 150 mm is filled with a sample, the sample is heated in a heating liquid, and the melting point is visually measured.
It was measured based on the capillary method according to the 064 standard.

The details of the types of plasticizers are as shown in Table 2.

[0035]

[Table 1]

[0036]

[Table 2]

Using the ceramic green sheet thus obtained, the width of the parallel portion was 10 mm, the length of the parallel portion was 40 mm, and the width of the grip portions at both ends was 20 mm. The dumbbell-shaped test piece having a total length of 100 mm was punched and stretched. The test piece was pulled at a speed of 500 mm / min using a testing machine to measure the sheet strength.

The punching workability is 80 for each sheet.
After heating to 0 ° C., punching was performed at 10 locations with a pin having a diameter of 60 μm, and observation was made with an electron microscope. Those having cracks around the punching were evaluated as defective, and those having no cracks were evaluated as good.

Further, the adhesion was carried out on a ceramic green sheet containing alumina and aluminum nitride as main components, and 5 sheets of each sheet were piled up at a temperature of 80.degree.
Thermocompression bonding was performed under a pressure of kgf / cm ² , the resulting laminate was broken, and its cross section was observed with a microscope. What is recognized as one layer is excellent, and what is clearly understood as 5 layers is good and completely. The separated ones were regarded as defective.

On the other hand, each of the above-mentioned ceramic green sheets for evaluation was bent 90 degrees or more and the handling property was evaluated, but no cracks were observed.

As for the ceramic green sheet containing barium titanate as a main component, 50 layers were stacked and pressed, and the laminated body was fired at 1200 ° C. to form terminal electrodes,
100 pieces were randomly sampled, the number of delaminations generated was inspected with an electron microscope, and delamination was evaluated after firing, but no delamination was observed.

[0042]

[Table 3]

As is clear from the results of Tables 1 to 3,
The sheets of Comparative Examples 1, 27 and 29 all have a sheet strength of 2.5.
It was confirmed that it was as low as MPa or less, and the sample numbers 2, 8, 21, and 22 which are outside the scope of the claims of the present invention also had a sheet strength of 2.
It is as low as 8 MPa or less, and Sample No. 14 has poor thermal decomposability and cannot be used. Sample Nos. 23, 24 and 25 are sludge unsuitable for sheet forming, such as poor dispersion or gelation. Is unsuitable because it has problems in punching workability and adhesion.

On the other hand, in all of the samples of the present invention, the sheet strength exceeds 3.1 MPa, the punching workability and the adhesion are excellent, and there is no problem in the thermal decomposition property. .

[0045]

As described above, the ceramic molding composition of the present invention comprises a ceramic raw material powder to which at least an acrylic additive and a solvent are added, and a phthalic acid ester or isophthalic acid ester having a predetermined melting point. Since the ceramic green sheet has a strength of more than 3 MPa and is excellent in flexibility and adhesiveness because it is added as a plasticizer or as a part of the plasticizer in a predetermined amount, it is easy to handle and cracks in post-processing such as punching. It is possible to provide a ceramic molding composition most suitable for thin and large-sized ceramic green sheets, since defects such as the above will not occur, and various post-processing machines will not be worn.

Continued Front Page (72) Mayor Yoshidome May 1-4 Yamashita Town, Kokubun City, Kagoshima Prefecture Kyocera Stock Company Research Institute

Claims (1)

[Claims] 1. A ceramic molding composition comprising a mixture of a ceramic raw material powder, at least an acrylic additive, a plasticizer and a solvent, wherein the plasticizer is at least 45 ° C.
A phthalic acid ester or an isophthalic acid ester having a melting point of more than 70 ° C. and less than 70 ° C., wherein the content of the phthalic acid ester or the isophthalic acid ester is 2 to 6% by weight based on the ceramic raw material powder. Ceramic molding composition.