JP3276261B2 - Ceramic mud and green sheet for forming green sheet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic slurry for forming a green sheet and a green sheet obtained by using the same.

[0002]

2. Description of the Related Art Ceramic circuit boards are widely used for electronic components. This type of ceramic circuit board is generally manufactured through the following steps.

[0003] First, ceramic powder is added to a solution containing a binder resin and a plasticizer, uniformly mixed and defoamed to prepare a ceramic slurry. Next, the ceramic slurry is applied on a peelable support, heated and dried, and then peeled from the support to obtain a green sheet.

[0004] The green sheet is punched into a predetermined shape, a predetermined circuit is printed on the surface thereof, and a plurality of the circuits are laminated and thermocompression-bonded as necessary, and the binder resin is decomposed by heating at high temperature. Then, it is heated at a high temperature to sinter the ceramic powder to obtain a ceramic circuit board.

[0005] This kind of green sheet is required to have good flexibility in order to improve handling properties. In order to improve such performance, it is known to use a water-soluble or organic solvent-soluble (water-insoluble) polyvinyl acetal resin, for example, a polyvinyl butyral resin, as a binder resin used for preparing a ceramic slurry. For example, JP-A-3-197511, JP-A-3-200805, and JP-A-4-175261
And JP-A-4-178404).

[0006]

In recent years, with the miniaturization of electronic equipment, there has been a demand for a ceramic circuit board having a small size and a large capacity. As a countermeasure, a ceramic powder having a finer particle size (for example, a particle size of 1
Attempts have been made to use a thin green sheet (for example, 10 μm or less) obtained by using a green sheet (for example, 10 μm or less).

However, in order to produce such a thin green sheet, the green sheet is obtained from a system in which a ceramic powder having a fine particle diameter is mixed with a water-soluble or organic solvent-soluble (water-insoluble) polyvinyl acetal resin. When the ceramic sheet is manufactured by heating and firing the green sheet, the decomposition of the polyvinyl acetal resin starts at a relatively high temperature of about 300 ° C. and ends at about 600 ° C. When this is heated at a rate of, for example, 10 ° C./min, the temperature range from the start of decomposition of the resin to the end of decomposition is relatively narrow,
Heat firing is performed relatively rapidly. As a result, the shrinkage of each thin ceramic sheet after heating and firing increases,
A trouble occurs in the performance of the obtained ceramic circuit board.

The present invention solves the above problems,
The aim is to increase the dispersibility of the ceramic powder, lower the decomposition initiation temperature during heating and firing, reduce the shrinkage rate after heating and firing, and achieve a green coating with good coating workability. An object of the present invention is to provide a ceramic slurry and a green sheet for forming a sheet.

[0009]

In order to achieve the above object, a ceramic slurry for forming a green sheet according to the present invention contains a polyvinyl acetal resin, polycaprolactone or an oxidizing agent, a ceramic powder, and a plasticizer. (The invention of claim 1).

Further, the ceramic slurry for forming a green sheet according to the present invention comprises:

[0011]

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(Where R represents hydrogen or an alkyl group, M represents hydrogen, lithium, sodium or potassium);
A modified polyvinyl acetal resin having at least one hydrophilic group selected from the group consisting of a quaternary amine, a quaternary ammonium salt and betaine, a polycaprolactone or an oxidizing agent, a ceramic powder, and a plasticizer. (The invention of claim 2).

Further, the green sheet of the present invention is obtained by forming the above-mentioned ceramic slurry for forming a green sheet into a sheet and then drying the sheet.

The polyvinyl acetal resin used in the present invention is obtained by dissolving polyvinyl alcohol in water, adding various aldehydes to this aqueous solution of polyvinyl alcohol,
It can be produced by performing an acetalization reaction by a known method.

On the other hand, the modified polyvinyl acetal resin used in the present invention has the above specific hydrophilic group, and the polyvinyl acetal resin is modified by the hydrophilic group. Such a modified polyvinyl acetal resin is obtained by using a modified polyvinyl alcohol having a hydrophilic group similar to the above, adding various aldehydes to an aqueous solution of the modified polyvinyl alcohol, and performing an acetalization reaction by a known method. Can be manufactured.

The above-mentioned modified polyvinyl alcohol is obtained by copolymerizing an ethylenic monomer having a specific hydrophilic group at the time of polymerization of polyvinyl acetate to obtain a vinyl acetate having a unit having the hydrophilic group. Producing a copolymer,
It can be obtained by saponifying the vinyl acetate copolymer. Most hydrophilic groups to be introduced need not be involved in the subsequent saponification and acetalization.

There are various types of ethylenic monomers having such a specific hydrophilic group. For example, when the hydrophilic group is -COOM, the following (1) and (2) )).

[0018]

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[0019]

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Taking the case where the hydrophilic group is —SO ₃ M as an example, the compounds represented by the following (3) to (10) are exemplified.

[0021]

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[0022]

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[0023]

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[0024]

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[0025]

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[0026]

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[0027]

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[0028]

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The polyvinyl alcohol and the modified polyvinyl alcohol preferably have a degree of polymerization of 200 to 3500 and a degree of saponification of 75 to 99.8 mol%. Polymerization degree is 20
If it is less than 0, it becomes difficult to synthesize the modified polyvinyl alcohol. Conversely, if the degree of polymerization exceeds 3,500, the viscosity of the aqueous solution becomes too high when used as an aqueous solution. The saponification degree is 7
If the amount is less than 5 mol%, the solubility in water is not sufficient, and if the degree of saponification exceeds 99.8 mol%, the synthesis of the modified polyvinyl alcohol becomes difficult.

The modification degree of the modified polyvinyl alcohol, that is, the ratio of the unit having the hydrophilic group is 0.0
It is preferably in the range of 1 to 5 mol%. in this case,
By mixing modified polyvinyl alcohol and unmodified polyvinyl alcohol, the proportion of the above units as a whole,
You may make it 0.01 to 5 mol%.

When the proportion of the unit having a hydrophilic group exceeds 5 mol%, the dispersibility of the ceramic powder cannot be increased. Conversely, if the proportion of the unit having a hydrophilic group is less than 0.01 mol%, the effect of increasing the dispersibility of the ceramic powder is small, and the effect of lowering the decomposition start temperature of the binder resin is also small.

Examples of the aldehyde used for acetalization of polyvinyl alcohol and modified polyvinyl alcohol include formaldehyde (including paraformaldehyde), acetaldehyde (including paraacetaldehyde), propionaldehyde, butyraldehyde, amylaldehyde, hexylaldehyde, heptylaldehyde, and the like. Examples thereof include 2-ethylhexylaldehyde, cyclohexylaldehyde, furfural, glyoxal, glutaraldehyde, and the like. These aldehydes are used alone or in combination of two or more. Particularly, those obtained by acetalization with acetaldehyde and / or butyraldehyde are preferable.

The degree of acetalization of the polyvinyl acetal resin and the modified polyvinyl acetal resin is generally in the range of 55 to 80 mol% in total acetalization degree when polycaprolactone is used, regardless of whether a single aldehyde or a mixed aldehyde is used. Is preferred. When the total acetalization degree is less than 55 mol%, the resin becomes water-soluble. On the other hand, when the total acetalization degree exceeds 80 mol%, the residual hydroxyl groups decrease and the dispersibility with the ceramic powder decreases.

When an oxidizing agent is used, the total acetalization degree is generally preferably in the range of 3 to 80 mol%. If the total acetalization degree is less than 3 mol%, the flexibility of the resin becomes poor, and if the total acetalization degree exceeds 80, on the other hand, the residual hydroxyl groups decrease and the dispersibility with the ceramic powder decreases.

When the total acetalization degree is generally 55 mol% or less, the resin becomes water-soluble, and when the total acetalization degree is generally 55 mol% or more, the resin becomes water-insoluble and organic solvent-soluble.

The modified polyvinyl acetal resin used in the present invention is obtained by acetalizing unmodified polyvinyl alcohol with various aldehydes to produce an unmodified polyvinyl acetal resin, in addition to the method using modified polyvinyl alcohol as described above. Alternatively, it can be produced by reacting the remaining hydroxyl group of this resin with an appropriate compound having the above-mentioned hydrophilic group.

An example of the method for producing the polyvinyl acetal resin used in the present invention will be described more specifically. First, the polyvinyl alcohol is dissolved in water. Then, in the presence of an acid catalyst such as hydrochloric acid, a predetermined amount of aldehyde, preferably acetaldehyde and / or butyraldehyde, is reacted with the aldehyde, preferably with acetaldehyde and / or butyraldehyde, to give the above-mentioned degree of acetalization. Wash, wash and dry. Thus, the polyvinyl acetal resin used in the present invention is obtained.

An example of the method for producing the modified polyvinyl acetal resin used in the present invention will be described more specifically. First, the above-mentioned modified polyvinyl alcohol alone or a mixture of modified polyvinyl alcohol and unmodified polyvinyl alcohol is dissolved in water. Then, in the presence of an acid catalyst such as hydrochloric acid, so as to give the degree of acetalization,
After reacting with a predetermined amount of aldehyde, preferably acetaldehyde and / or butyraldehyde, it is neutralized with an alkali such as sodium hydroxide, washed with water and dried. Thus, the modified polyvinyl acetal resin used in the present invention is obtained.

The ceramic slurry for forming a green sheet according to the present invention comprises the above-mentioned specific polyvinyl acetal resin or a modified polyvinyl acetal resin having a hydrophilic group, polycaprolactone or an oxidizing agent, ceramic powder,
It is prepared by blending a plasticizer and uniformly dissolving it in water or an organic solvent by a conventional method.

The polyvinyl acetal resin and the modified polyvinyl acetal resin are contained in the ceramic slurry at 3 to 15 times.
It is preferable to mix in the range of weight%. If the amount of the resin is more than 15% by weight, the viscosity of the ceramic slurry becomes too high to lower the dispersibility, and the shrinkage ratio of the obtained green sheet when firing is increased. On the other hand, when the amount of the resin is less than 3% by weight, the polyvinyl acetal resin and the modified polyvinyl acetal resin are insufficiently dispersed in the entire ceramic powder, and the resulting green sheet is not sufficiently flexible, and cracks or the like after firing. Is more likely to occur.

As the polycaprolactone, those represented by the following structural formula are used.

[0042]

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In the formula, n represents an integer of 60 to 800. For example, PLACCEL HIP manufactured by Daicel Chemical Industries,
H4, H5, H7, etc. correspond. When n is less than 60, since the molecular weight is low, it becomes brittle when formed into a green sheet, and it becomes difficult to produce a thin-layer type green sheet. When n exceeds 800, the molecular weight is high. The viscosity becomes too high when is made into a slurry.

The polycaprolactone is preferably blended in a range of 5 to 250% by weight based on the polyvinyl acetal resin or the modified polyvinyl acetal resin.
If the amount of polycaprolactone exceeds 250% by weight, the green sheet becomes very brittle and a thin green sheet cannot be beaten. Conversely, if the blending amount of polycaprolactone is less than 5% by weight, the binder decomposability of the sheet due to the blending of polycaprolactone is not sufficient.

Examples of the oxidizing agent include organic acid metal salts such as cobalt naphthenate, cobalt octylate, lead octylate, zinc octylate and iron octylate; oxidizing assistants such as ammonium nitrate and nitrocellulose; and hydroperoxide-based peroxides. An oxide (for example, Perbutyl H, Park Mill P, Park Mill H manufactured by NOF Corporation) or the like is used.

The above-mentioned oxidizing agent is used in an amount of 0.1 to 0.1 with respect to the polyvinyl acetal resin or the modified polyvinyl acetal resin.
It is preferable to mix in the range of 10% by weight. If the amount of the oxidizing agent is more than 10% by weight, the sheet is rapidly decomposed at an early stage of firing the sheet, and a uniform sheet cannot be obtained.
Conversely, if the amount of the oxidizing agent is less than 0.1% by weight, the degradability of the sheet binder due to the oxidizing agent is not sufficient.

As the ceramic powder, a ceramic powder conventionally used for producing a ceramic green sheet is used. Examples of such ceramic powders include powders of alumina, zirconia, aluminum silicate, titanium oxide, zinc oxide, barium titanate, magnesia, sialon, spinel mullite, crystallized glass, silicon carbide, silicon nitride, aluminum nitride, and the like. No.

Further, MgO is added to these ceramic powders.
—SiO ₂ —CaO system, B ₂ O ₃ —SiO ₂ system, PbO
—B ₂ O ₃ —SiO ₂ system, CaO—SiO ₂ —MgO—
B ₂ O ₃ system or _{PbO-SiO 2 -B 2 O 3} -CaO
A glass frit such as a system may be added.

Particularly, a thin green sheet (for example, 10 μm)
m or less), it is preferable to use ceramic powder having a finer particle size (for example, a particle size of 1 μm or less).

The above ceramic powder is preferably blended in the ceramic slurry in an amount of 30 to 80% by weight. When the amount of the ceramic powder exceeds 80% by weight,
The viscosity of the ceramic slurry becomes too high and the kneadability is reduced. On the other hand, when the amount of the ceramic powder is less than 30% by weight, the viscosity of the ceramic slurry becomes too low, and the handling property when forming the sheet is deteriorated.

As the plasticizer, any plasticizer can be used as long as it has excellent compatibility with the polyvinyl acetal resin and the modified polyvinyl acetal resin.

When the resin is water-soluble, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, glycerin, hexamethylene glycol or the like is used as a plasticizer.

When the resin is soluble in an organic solvent (water-insoluble), phthalic acid esters such as dibutyl phthalate, dioctyl phthalate, diisodecyl phthalate and butyl benzyl phthalate as plasticizers, tricresyl phosphate, tributyl phosphate, etc. Phosphate esters such as triethyl phosphate, fatty acid esters such as methylacetyl ricinoleate, dibutyl sebacate and dioctyl adipate, and glycol derivatives such as butylphthalyl glycolate and triethylene glycol-2-ethylbutyrate are used. Can be

The above plasticizer is added to the ceramic slurry at a concentration of 0.1%.
It is preferable to mix in the range of 1 to 10% by weight. If the compounding amount of the plasticizer exceeds 10% by weight, the handleability at the time of forming the sheet is deteriorated. Conversely, if the amount of the plasticizer is less than 0.1% by weight, the flexibility of the sheet due to the addition of the plasticizer cannot be sufficiently obtained.

The water or the organic solvent dissolves the polyvinyl acetal resin and the modified polyvinyl acetal resin and gives a suitable kneading property to the ceramic slurry, and is used in an amount of 20 to 80% by weight in the ceramic slurry. Is preferred. When dissolving with an organic solvent, acetone, ketones such as methyl ethyl ketone, methanol, ethanol,
Alcohols such as butanol and aromatic hydrocarbons such as toluene and xylene are used.

When water is used as a solvent, there is an advantage that fire and environmental problems do not occur as compared with the case where an organic solvent is used as a solvent.

When an organic solvent is used as a solvent, the ceramic slurry can be dried more quickly than when water is used as a solvent, and there is an advantage that the productivity of green sheets is improved.

The ceramic slurry of the present invention contains a lubricant, a deflocculant, a wetting agent, an antistatic agent, an antifoaming agent, a drying accelerator, etc., as needed, within a range where the object can be achieved. May be.

The thus-obtained ceramic slurry for forming a green sheet is defoamed, if necessary, applied to a support such as a releasable polyester film and heated.
The water or organic solvent is removed by drying, and then the green sheet is peeled off from the support to produce a green sheet.

In order to obtain a hybrid type multilayer ceramic circuit board using this green sheet, the green sheet is punched into a predetermined shape and size, a circuit is printed on the surface thereof, and a plurality of green sheets, for example, Ten sheets are laminated, and they are integrated by thermocompression bonding to obtain a laminated body. Then, the laminate is heated to a high temperature (for example, about 600 ° C.).
To decompose the binder resin almost completely, and further heat it to a high temperature (for example, about 1600 ° C.) to sinter the ceramic powder to obtain a hybrid type multilayer ceramic circuit board.

[0061]

[Function] By using polycaprolactone or an oxidizing agent together with a polyvinyl acetal resin or a modified polyvinyl acetal resin, the main chain is more likely to be cut than when not blended. It is considered that the decomposition start temperature and the decomposition end temperature of the compound decrease, and as a result, calcination can be performed at a lower temperature than before.

Further, by the action of the acetal ring and the specific hydrophilic group, the intermolecular association and crystallization of the polyvinyl acetal resin and the modified polyvinyl acetal resin are suppressed. A ceramic slurry for forming a green sheet and a green sheet having good coating workability with less change in viscosity over time can be obtained.

When a polyvinyl acetal resin modified by the introduction of the above-mentioned specific hydrophilic group is used as the binder resin, these ionic hydrophilic groups can be used as non-modified polyvinyl acetal resin. It exhibits stronger surface activity than the ionic residual hydroxyl groups, and in combination with the action of the residual hydroxyl groups, dispersibility of the ceramic powder in the resin is improved.

Furthermore, in the polyvinyl acetal resin modified by the introduction of the specific hydrophilic group described above, the main chain is more likely to be randomly cut than in the unmodified polyvinyl acetal resin. This also has the effect of lowering the decomposition start temperature of the resin.

[0065]

EXAMPLES Examples and comparative examples of the present invention will be described below.

The evaluation of the performance of the ceramic mud and the green sheet was carried out with respect to the releasability, flexibility, decomposition start temperature and decomposition end temperature by the following methods.

[0067] The green sheet drawn on the peelable release treated polyester film, dried, examined by state visually when peeled by hand, ○; very good is uniformly peeled off.

Δ: Part of the green sheet remains on the film.

×: The strength of the green sheet was low, and the green sheet could not be peeled off. The evaluation was made based on three levels.

The flexibility of the flexible green sheet was examined by touch and evaluated on four levels: ◎ (very good), （(good), △ (good), and × (bad).

Decomposition start temperature and decomposition end temperature The above polyvinyl acetal resin was dissolved at a concentration of 10% by weight in a methyl ethyl ketone / toluene mixed solution (1: 1 weight ratio), and the caprolactone or oxidizing agent used above was added to the resin. 3 wt% was added and dissolved, applied onto a film, and dried at 100 ° C. for 3 hours to prepare a polyvinyl acetal resin to which caprolactone or an oxidizing agent was added. This was sampled in an amount of 10 mg, and the temperature was raised at a rate of 10 ° C./min in a nitrogen atmosphere. The temperature at which the decomposition of the resin started was defined as the decomposition start temperature.
The temperature at the time when became the decomposition end temperature. The tester used was TGA (thermogravimetric analyzer) manufactured by Seiko Denshi.

(Example 1) Degree of polymerization 800, degree of saponification 98
193 g of mol% polyvinyl alcohol was added to pure water 2900
The mixture was stirred and dissolved at a temperature of 90 ° C. for about 2 hours. The solution was cooled to 28 ° C., and 201 g of hydrochloric acid having a concentration of 35% by weight and 112 g of n-butyraldehyde were added thereto.
The liquid temperature was lowered to 20 ° C., and an acetalization reaction was performed while maintaining this temperature to precipitate a reaction product. After that, the liquid temperature was set to 3
The reaction was completed by keeping the mixture at 0 ° C. for 5 hours, and neutralized, washed with water and dried by a conventional method to obtain a white powder of a polyvinyl acetal resin.

The obtained polyvinyl acetal resin was treated with DM
Was dissolved in SO-d ₆ (dimethylsulfoxide), ¹³ C
When the degree of acetalization (degree of butyralization) was measured using -NMR (nuclear magnetic resonance spectrum), the degree of butyralization was 67 mol%.

Production of Ceramic Slurry 10 parts by weight of this polyvinyl acetal resin was added to a mixed solvent of 30 parts by weight of toluene and 15 parts by weight of methyl ethyl ketone and dissolved by stirring. Polycaprolactone (PLACCL HI manufactured by Daicel Chemical Industries, Ltd.) was added to this resin solution.
P) 3 parts by weight and 5 parts by weight of dibutyl phthalate as a plasticizer were added and dissolved by stirring. In the resin solution thus obtained,
Barium titanate (average particle size of 0.
1 μm), and mixed with a ball mill for 48 hours to obtain a ceramic slurry in which barium titanate powder was dispersed.

Production of Green Sheet This ceramic slurry was applied to a release-treated polyester film to a thickness of about 12 μm, air-dried at room temperature for 30 minutes, and further dried at 60-80 ° C. for 1 hour in a hot air drier. The solvent was evaporated to obtain a thin green sheet having a thickness of 8 μm. Table 1 shows the evaluation results of the peelability, flexibility, decomposition start temperature, and decomposition end temperature of the ceramic mud and the green sheet.

(Examples 2 to 5 and Comparative Examples 1 to 3) Polyvinyl alcohol and aldehyde were changed as shown in Table 1. Other than that, it carried out similarly to Example 1. Table 1 shows the results.

[0077]

[Table 1]

(Example 6) Degree of polymerization 800, degree of saponification 98
193 g of mol% polyvinyl alcohol was added to pure water 2900
g and stirred at a temperature of 90 ° C. for about 2 hours to dissolve. The solution was cooled to 28 ° C. and the concentration was 35% by weight.
Of hydrochloric acid and 112 g of n-butyraldehyde were added, the liquid temperature was lowered to 20 ° C., and this temperature was maintained to carry out an acetalization reaction to precipitate a reaction product. Thereafter, the liquid temperature was maintained at 30 ° C. for 5 hours to complete the reaction, followed by neutralization, washing with water and drying by a conventional method to obtain a white powder of a polyvinyl acetal resin.

The obtained polyvinyl acetal resin was treated with DM
Was dissolved in SO-d ₆ (dimethylsulfoxide), ¹³ C
When the degree of acetalization (degree of butyralization) was measured using -NMR (nuclear magnetic resonance spectrum), the degree of butyralization was 67 mol%.

Production of Ceramic Slurry 10 parts by weight of the polyvinyl acetal resin was added to toluene 3
The mixture was added to a mixed solvent of 0 parts by weight and 15 parts by weight of methyl ethyl ketone and dissolved by stirring. To this resin solution, 0.5 parts by weight of ammonium nitrate as an oxidizing agent and 5 parts by weight of dibutyl phthalate as a plasticizer were added and dissolved by stirring. To the resin solution thus obtained, 100 parts by weight of barium titanate (average particle size: 0.1 μm) was added as a ceramic powder, and mixed with a ball mill for 48 hours to obtain a ceramic slurry in which the barium titanate powder was dispersed.

Production of Green Sheet This ceramic slurry was applied to a release-treated polyester film to a thickness of about 12 μm, air-dried at room temperature for 30 minutes, and further dried at 60 to 80 ° C. for 1 hour in a hot air drier. The organic solvent was evaporated to obtain a thin green sheet having a thickness of 8 μm.

Table 2 shows the performance evaluation results of the above-mentioned ceramic slurry and green sheet.

(Examples 7 to 10 and Comparative Examples 4 to 6) The polyvinyl alcohol, aldehyde and oxidizing agent were changed as shown in Table 2. Other than that, it carried out similarly to Example 6.
Table 2 shows the results.

[0084]

[Table 2]

(Example 11) Degree of polymerization: 800, degree of saponification: 9
200 g of 8 mol% polyvinyl alcohol is added to pure water 160
0 g, and the mixture was stirred and dissolved at a temperature of 90 ° C. for about 2 hours. The solution was cooled to 45 ° C. and the concentration was 35% by weight.
50 g of hydrochloric acid, and further cooled to 35 ° C., 20 g of n-butyraldehyde having a purity of 99% and 99%
25 g of acetaldehyde was added dropwise over 2 hours, and 3 g
The acetalization reaction was performed at 5 ° C. for 3 hours. Thereafter, the liquid temperature was cooled to 20 ° C., and 192 g of a 10% by weight aqueous sodium hydroxide solution was added under stirring to obtain a transparent solution of a polyvinyl acetal resin.

The obtained transparent solution of the polyvinyl acetal resin was applied on a polyethylene film and dried,
A transparent film was prepared, and this transparent film was DMSO-
dissolved in d ₆ (dimethyl sulfoxide), ¹³ C-NM
When the degree of acetalization (degrees of butyralization and acetoacetalization) was measured using R (nuclear magnetic resonance spectrum), the degree of butyralization was 10 mol% and the degree of acetoacetalization was 15 mol%.

Production of Ceramic Slurry 60 g of a transparent solution (concentration: 20% by weight) of this polyvinyl acetal resin was mixed and dissolved in 120 g of pure water, and 0.6 g of ammonium nitrate was used as an oxidizing agent, and polyethylene glycol (average molecular weight: 200 4 g) and barium titanate as ceramic powder (average particle size 0.1
μm) and mixed with a ball mill for 48 hours to obtain a ceramic slurry in which barium titanate powder was dispersed.

Production of Green Sheet This ceramic slurry was defoamed under reduced pressure of 5 mmHg while stirring to adjust the viscosity to 10 poise, and then applied to a release-treated polyester film to a thickness of about 15 μm, For 1 day, and further dried with a hot air dryer at 110 ° C. for 3 hours to evaporate water, thereby obtaining a thin green sheet having a thickness of 8 μm.

The above-mentioned ceramic slurry and green sheet were evaluated for peelability, flexibility, decomposition start temperature and decomposition end temperature in the same manner as in Example 1. Table 3 shows the results.

(Examples 12 to 15 and Comparative Examples 7 to 9) The polyvinyl alcohol, aldehyde and oxidizing agent were changed as shown in Table 3. Other than that, it carried out similarly to Example 11. Table 3 shows the results.

[0091]

[Table 3]

Example 16 Production of Modified Polyvinyl Acetal Resin 193 g of itaconic acid-modified polyvinyl alcohol having a degree of polymerization of 800, a degree of saponification of 98 mol%, and a degree of modification of 2 mol% was added to 2900 g of pure water. Stir for about 2 hours to dissolve. The solution was cooled to 28 ° C.,
201 g by weight of hydrochloric acid and 112 g of n-butyraldehyde
Was added, the liquid temperature was lowered to 20 ° C., and this temperature was maintained to carry out an acetalization reaction to precipitate a reaction product. Thereafter, the liquid temperature was maintained at 30 ° C. for 5 hours to complete the reaction,
After neutralization, washing and drying by a conventional method, a white powder of itaconic acid-modified polyvinyl acetal resin was obtained.

The resulting modified polyvinyl acetal resin was dissolved in DMSO-d ₆ (dimethyl sulfoxide),
^{When the} degree of acetalization (degree of butyralization) was measured using ¹³ C-NMR (nuclear magnetic resonance spectrum), the degree of butyralization was 67 mol%.

Using this modified polyvinyl acetal resin, a ceramic slurry and a green sheet were produced in the same manner as in Example 1, and the peelability, flexibility, decomposition start temperature and decomposition end temperature were evaluated. Table 4 shows the results.

(Examples 17 to 20 and Comparative Examples 7 to 9) Polyvinyl alcohol and aldehyde were changed as shown in Table 4. Otherwise, the procedure was the same as in Example 16. Table 4 shows the results.

[0096]

[Table 4]

Example 21 Production of Modified Polyvinyl Acetal Resin 193 g of itaconic acid-modified polyvinyl alcohol having a degree of polymerization of 800, a degree of saponification of 98 mol%, and a degree of modification of 2 mol% was added to 2900 g of pure water. Stir for about 2 hours to dissolve. The solution was cooled to 28 ° C.,
201 g by weight of hydrochloric acid and 112 g of n-butyraldehyde
Was added, the liquid temperature was lowered to 20 ° C., and this temperature was maintained to carry out an acetalization reaction to precipitate a reaction product. Thereafter, the liquid temperature was maintained at 30 ° C. for 5 hours to complete the reaction,
After neutralization, washing and drying by a conventional method, a white powder of itaconic acid-modified polyvinyl acetal resin was obtained.

The obtained modified polyvinyl acetal resin was dissolved in DMSO-d ₆ (dimethyl sulfoxide),
^{When the} degree of acetalization (degree of butyralization) was measured using ¹³ C-NMR (nuclear magnetic resonance spectrum), the degree of butyralization was 67 mol%.

Using this modified polyvinyl acetal resin, a ceramic slurry and a green sheet were produced in the same manner as in Example 6, and the peelability, flexibility, decomposition start temperature and decomposition end temperature were evaluated. Table 5 shows the results.

(Examples 22 to 25 and Comparative Examples 13 to 1)
5) The modified polyvinyl alcohol, aldehyde, and oxidizing agent were changed as shown in Table 5. Other than that, it carried out similarly to Example 6. Table 5 shows the results.

[0101]

[Table 5]

Example 26 Production of Modified Polyvinyl Acetal Resin 200 g of itaconic acid-modified polyvinyl alcohol having a degree of polymerization of 800, a degree of saponification of 98 mol% and a degree of modification of 2 mol% was added to 1600 g of pure water, and the temperature was 90 ° C. Stir for about 2 hours to dissolve. The solution was cooled to 45 ° C.,
50% by weight of hydrochloric acid was added and further cooled to 35 ° C.
20 g of n-butyraldehyde having a purity of 99% and 25 g of acetaldehyde having a purity of 99% were added dropwise thereto over 2 hours, and an acetalization reaction was performed at 35 ° C. for 3 hours. Thereafter, the liquid temperature was cooled to 20 ° C., and 192 g of a 10% by weight aqueous sodium hydroxide solution was added with stirring to obtain a transparent solution of an itaconic acid-modified polyvinyl acetal resin.

The resulting modified polyvinyl acetal resin
Apply clear solution on polyethylene film and dry
To create a transparent film, and apply this transparent film to DMS
Od ₆(Dimethylsulfoxide)¹³C-
Acetalization using NMR (nuclear magnetic resonance spectrum)
Degree (butyralization degree and acetoacetalization degree)
As a result, the butyral degree was 10 mol%,
The degree of tarification was 15 mol%.

Using this modified polyvinyl acetal resin, a ceramic slurry and a green sheet were produced in the same manner as in Example 11, and the peelability, flexibility, decomposition start temperature and decomposition end temperature were evaluated. Table 6 shows the results.

(Examples 27 to 30 and Comparative Examples 16 to 1)
8) The modified polyvinyl alcohol, aldehyde, and oxidizing agent were changed as shown in Table 6. Other than that, it carried out similarly to Example 11. Table 6 shows the results.

[0106]

[Table 6]

[0107]

The ceramic slurry for green sheet molding according to the present invention is a polyvinyl acetal resin or a modified polyvinyl acetal resin having the above-mentioned specific hydrophilic group, polycaprolactone or an oxidizing agent, ceramic powder,
And it contains a plasticizer, and the action of this oxide makes it easier for the main chain of polyvinyl alcohol or modified polyvinyl alcohol to be cut. As a result, the decomposition start temperature and the decomposition end temperature of the resin at the time of heating and firing are lowered, and firing at a low temperature becomes possible. As a result, a homogeneous thin green sheet having a very large number of laminations can be produced, and lead having a low melting point Also, when a composite perovskite compound containing the above is used as a ceramic powder, a green sheet can be suitably produced.

Further, since the green sheet of the present invention uses a tough polyvinyl acetal resin or a modified polyvinyl acetal resin, even when a thin green sheet having a thickness of 10 μm or less is peeled from the release-treated polyester film, a uniform thickness is obtained. Can be peeled off.

Further, due to the action of the acetal ring and the specific hydrophilic group, the intermolecular association and crystallization of the polyvinyl acetal resin and the modified polyvinyl acetal resin are suppressed. There is an advantage that the viscosity does not easily change over time, the coating workability is good, and a uniform thin green sheet can be easily produced.

When a polyvinyl acetal resin modified by the introduction of the above-mentioned specific hydrophilic group is used as the binder resin, the ionic hydrophilic group becomes a non-ionic non-ionic group of the unmodified polyvinyl acetal resin. In combination with the action of the residual hydroxyl groups of the resin, the dispersibility of the ceramic powder in the resin is improved. Therefore, it becomes possible to use ceramic powder having a finer particle size, and as a result, a thinner green sheet can be manufactured.

Claims (3)

(57) [Claims] 1. A ceramic slurry for forming a green sheet, comprising a polyvinyl acetal resin, polycaprolactone or an oxidizing agent, a ceramic powder, and a plasticizer. (2) (Where R represents hydrogen or an alkyl group, M represents hydrogen, lithium, sodium or potassium), a tertiary amine,
A modified polyvinyl acetal resin having at least one hydrophilic group selected from the group consisting of a quaternary ammonium salt and betaine, a polycaprolactone or an oxidizing agent, a ceramic powder, and a plasticizer. Ceramic mud for green sheet molding. 3. A green sheet obtained by shaping the ceramic slurry for forming a green sheet according to claim 1 into a sheet and then drying the sheet.