JPH0987040A - Ceramic green body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a ceramic green body having excellent high strength while keeping excellent defatting property characteristic of an acrylic resin. SOLUTION: This ceramic green body consists of 100 pts.wt. ceramic powder such as aluminum nitride powder and 0.1-30 pts.wt. binder composed of an acrylic resin and a polyvinyl butylal and the proportion of the polyvinyl butylal in the binder is 0.1-10wt.%.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a novel ceramic green body. Specifically, it is a ceramic green body having excellent strength while maintaining the good degreasing property of the acrylic resin.

[0002]

2. Description of the Related Art Conventionally, as a method for producing a ceramic sintered body, a method of granulating ceramic powder into granules, followed by molding with a dry press to obtain a press-molded body and firing, or wet-molding of the ceramic powder. A green sheet is generally used to obtain a green sheet, and then, a green sheet is punched into a predetermined shape and then fired.

As a method of manufacturing a ceramic green body,
In the production of the former press-molded body, a binder, an organic solvent, etc. are added to and mixed with the ceramic powder, and the ceramic powder is granulated by a known method such as a spray dryer method, and then the ceramic granules are molded into a mold or the like. A method is known in which a ceramic press-molded body is obtained by filling the material in a molding die and press-molding it with a press molding machine.

On the other hand, in the latter case of manufacturing a green sheet, a binder, an organic solvent and the like are added to ceramic powder and mixed, and after molding by a doctor blade method or the like, the obtained green sheet is punched by a predetermined die. The method of processing into a specific size and shape is generally adopted.

As the ceramic powder, various ceramic powders such as aluminum nitride, alumina, silicon carbide, silicon nitride and zirconia are used depending on the use such as electronic materials and structural materials.

The ceramic green body obtained as described above is subjected to a so-called degreasing treatment for thermally decomposing and removing the binder component contained as a component in the manufacturing process of the sintered body.

In this degreasing treatment, recently, the use of an acrylic resin which is excellent in thermal decomposability and has little residual carbon after firing has been studied for the purpose of maximizing the original material properties of ceramics.

[0008]

However, the ceramic green body produced by using such an acrylic resin as a binder has a drawback that the strength of the obtained ceramic green body is weak, and in order to cover such a drawback, an acrylic resin is used. It was necessary to mix a large amount.

Therefore, in the degreasing treatment, cracks and cracks are likely to occur due to abrupt volume contraction of the obtained degreased body, and degreasing takes a long time.

Particularly, in the case of a thick ceramic green body having a thickness of 0.8 mm or more, cracks are easily generated in the green sheet during the molding of the ceramic green body, and the maximum amount is about twice that of conventional polyvinyl butyral. Needed acrylic resin. As a result, in addition to the above-mentioned problems, there is a problem that the drying property during molding of the ceramic green body is poor and the productivity of the green sheet is poor.

[0011]

[Means for Solving the Problems] The present inventors have conducted extensive studies to solve the above problems. As a result, by adding a specific amount of polyvinyl butyral to the acrylic resin, which is the binder component of the ceramic green body, the degreasing property of the acrylic resin is hardly impeded, and the strength of the obtained ceramic green body is improved. The present invention has been significantly improved, and it has been found that such an object is achieved and obtained, and the present invention has been proposed.

That is, it comprises 100 parts by weight of ceramic powder and 0.1 to 30 parts by weight of a binder composed of an acrylic resin and polyvinyl butyral, and the proportion of the polyvinyl butyral in the binder is 0.1 to 10% by weight.
It is a ceramic green body characterized by

In the present invention, as the shape of the ceramic green body, a known shape is adopted without particular limitation. For example,
Examples include a sheet shape, a plate shape, a prismatic shape, a cylindrical shape, a spherical shape, and a box shape. Among these ceramic green bodies, the ceramic green body to which the present invention is preferably applied is 0.8 m.
It is a thick molded body having a thickness of m or more.

As the ceramic powder used in the present invention, known ones can be used without any limitation. Examples thereof include aluminum nitride, alumina, silicon carbide, silicon nitride and zirconia. Above all, the residual carbon after firing the green body is preferably used for aluminum nitride, which has a great influence on the material properties of the sintered body, particularly the thermal conductivity.

Generally, in order to obtain an aluminum nitride sintered body having excellent thermal conductivity, it is preferable that the aluminum nitride powder used has a small oxygen content and a small amount of cation impurities. That is, when AlN has an aluminum nitride composition,
Oxygen content as impurities is 1.5 wt% or less, cationic impurities is 0.3 wt% or less, preferably oxygen content is 0.4 to 1.3 wt%, cationic impurities are 0.2 wt%
The following aluminum nitride powders are suitable. The above-mentioned cation impurities do not include bonded Al when the surface of aluminum nitride is inevitably oxidized in the air and Al—N bonds are replaced by Al—O bonds.

Further, it is preferable that the particles of the ceramic powder such as the aluminum nitride powder have a small particle diameter. For example, the average particle diameter (means the average particle diameter of the agglomerated particles measured by a centrifugal particle size distribution measuring device) is 5 μm.
Hereafter, it is preferably 3 μm or less.

The most significant feature of the present invention is that a binder composed of an acrylic resin and polyvinyl butyral is used as the binder constituting the ceramic green body, and the proportion of the polyvinyl butyral in the binder is 0.
1 to 10% by weight, preferably 0.5 to 7% by weight.

The mixing ratio of the above polyvinyl butyral is
If the amount is less than 0.1% by weight, the effect of improving the strength of the acrylic resin is insufficient and the object of the present invention cannot be achieved. Further, the mixing ratio of the polyvinyl butyral is 1
If it exceeds 0% by weight, the compatibility between polyvinyl butyral and acrylic resin is poor, so when a ceramic green body is obtained by the wet molding method described below, the viscosity and thixotropy of the slurry of the ceramic powder increase, Problems such as a decrease in density of the obtained green sheet and generation of streak-like grooves on the green sheet during sheet formation occur, and physical properties and the like of a ceramic sintered body obtained by degreasing and firing the green sheet deteriorate.

Further, when a ceramic green body is manufactured by the press molding described later, it is difficult to obtain a high-density press molded body because the bulk density of the granules is lowered.
Physical properties and the like of the ceramic sintered body obtained by degreasing and firing this are deteriorated.

Further, since the degreasing property of the ceramic green body is also deteriorated, there is a problem that the physical properties of the finally obtained ceramic paste are deteriorated.

Specific examples of the acrylic resin preferably used in the present invention include polymethacrylic acid esters such as polymethylmethacrylate, poly-2-ethylhexylmethacrylate, polyethylmethacrylate, polybutylmethacrylate and polyoctylmethacrylate, and polymethacrylic acid. In addition to polyacrylic acid esters and polyacrylic acid such as acid, polymethyl acrylate, poly 2-ethylhexyl acrylate, polyethyl acrylate, polybutyl acrylate, polyoctyl acrylate, etc., poly 2-hydroxyethyl methacrylate having a hydroxyl group or an amino group, Examples thereof include methacrylic acid ester derivative polymers such as polydimethylaminoethyl methacrylate, and one kind or a mixture of two or more kinds is used.

The glass transition temperature (T
Although g) is not particularly limited, it is preferable to use a material of −10 to 50 ° C., preferably 5 to 30 ° C., from the viewpoint of degreasing property and punching workability when the ceramic green body is a sheet. .

The molecular weight of the acrylic resin is not particularly limited, but is generally 3,000 to 1,000,0.
00, preferably 5,000 to 500,000, which is suitable because a flexible molded body can be obtained when the ceramic green body is a sheet.

The acid value of the acrylic resin is not particularly limited, but when the ceramic green body is manufactured by reusing the residual material generated in the molding and processing steps of the ceramic green body, 0.01 KOH mg / mg / g or more,
It is preferably less than 1.0 KOH mg / g. Here, the acid value is a quantitative value of the amount of free fatty acid of the acrylic resin.

The polyvinyl butyral, which is another component of the binder, is not particularly limited, and known ones can be used. As the molecular weight of butyral,
In general, when 3,000 to 1,000,000, preferably 5,000 to 300,000 is used, high strength of the ceramic green body is achieved, and when the ceramic green body is a sheet, It is suitable for obtaining a flexible molded product.

From the viewpoint of compatibility with the acrylic resin, it is preferable to use a polybutyral having a butyralization degree of 60% by weight or more, and further 70% by weight or more. The degree of butyral is JIS K6728.
Determine the vinyl acetate component and vinyl alcohol component by
It is a value calculated by the following formula.

[0027]

[Equation 1]

In the present invention, the mixing ratio of the binder composed of acrylic resin and polyvinyl butyral to the ceramic powder is 0.1 to 30 parts by weight, of which 2 to 15 parts by weight are mixed with 100 parts by weight of the ceramic powder. The range is more preferable. When the amount of the binder is less than 0.1 parts by weight, the strength of the ceramic green body is low, and when it exceeds 30 parts by weight,
The degreasing property of the ceramic green body is deteriorated, and the physical properties of the ceramic sintered body obtained by firing the ceramic green body are deteriorated.

Further, the ceramic green body of the present invention,
A plasticizer is optionally used for the purpose of imparting more flexibility. As the plasticizer used, known plasticizers can be used without particular limitation. Specific examples of those preferably used as plasticizers are polyethylene glycol and its derivatives; phthalic acid esters such as dimethyl phthalate, dibutyl phthalate, benzyl butyl phthalate and dioctyl phthalate; stearic acid such as butyl stearate. Esters; tricresole phosphate; tri-N-butyl phosphate; glycerin and the like. The amount of these plasticizers added varies depending on the properties of the ceramic powder, the type of binder, the type of organic solvent used during production, the amount used, etc., and cannot be unconditionally limited, but generally 15 parts by weight per 100 parts by weight of ceramic powder Parts or less, preferably 0.4 to 15
It may be appropriately selected and used from the range of parts by weight.

Further, in addition to the above composition, the ceramic green body of the present invention has various ceramic powders,
A known sintering aid is blended. In the case of aluminum nitride, a sintering aid known to be used for sintering, for example, alkaline earth metal oxides such as calcium oxide and strontium oxide; rare earth oxides such as yttrium oxide and lanthanum oxide; calcium aluminate and the like. The ratio of the composite oxides, etc. in the total amount with the aluminum nitride powder is 0.1 to 0.1%.
You may use it in the range of 10 weight%.

The method for producing the ceramic green body of the present invention is not particularly limited, and known molding methods can be adopted without particular limitation. For example, ceramic powder and a binder are mixed with an organic solvent to prepare mud, and the mud is wet-molded by a known method, that is, a doctor blade method or the like to obtain a green body such as a green sheet. Examples of the method include a method of performing a process such as punching if necessary, a method of granulating the mud by a spray dryer method or the like, and then molding the granules by a dry pressing method.

The mixing method of the ceramic powder and the binder is arbitrarily selected according to various molding methods, but in order to enhance the dispersion of the ceramic powder in the binder, the mixing is usually performed in two steps. . That is, the first time, aluminum nitride powder and an organic solvent, if necessary, a sintering aid and a surfactant are added and mixed, and the second time, the binder and the remaining solvent in the first mixture. In addition mixed. In the second mixing, a plasticizer may be added if necessary.

The above method is particularly preferably used in the production of green sheets by wet molding, in which the amount of binder added is relatively large.

The acrylic resin and polyvinyl butyral may be mixed in the above-mentioned proportions at the time of preparing the mud by mixing them. Illustrative examples of suitable methods include a method in which an acrylic resin and polyvinyl butyral are dissolved and mixed in a solvent in advance, a method in which each of them is copolymerized in the above-described proportions, and the like are used.

As the surface-active agent used as required when producing the ceramic green body of the present invention, known ones are not limited at all depending on the ceramic powder used. For example, in the case of aluminum nitride powder, a nonionic surface active agent is preferably used, and in particular, a hydrophilic / lipophilic balance (hereinafter abbreviated as HLB) of 4.5 to 18 is the aluminum nitride green sheet. It is preferably used because it increases the sheet density. The HL in the present invention
B is a value calculated by the Davis equation. Specific examples of the surfactant include carboxylated trioxyethylene tridecyl ether, diglycerin monooleate, diglycerin monostearate, carboxylated heptaoxyethylene tridecyl ether, tetraglycerin monooleate, hexaglycerin monooleate. ,
Examples thereof include polyoxyethylene sorbitan monolaurate and polyoxyethylene sorbitan monooleate.

The surface active agents in the present invention may be used as a mixture of two or more kinds, and the HLB at that time can be calculated by the arithmetic average of the HLB of each surface active agent.

These surface active agents are usually used in the ceramic powder 10 in order to produce a good ceramic green body.
It is 0.01 to 10 parts by weight, preferably 0.02 to 3.0 parts by weight, relative to 0 parts by weight. 0.01% surfactant
If it is less than 10 parts by weight, the dispersion of the sludge will be insufficient, and if it is more than 10 parts by weight, the strength of the green body tends to decrease.

Further, as the organic solvent preferably used for producing the ceramic green body of the present invention, for example, ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone; alcohols such as ethanol, propanol and butanol; benzene, toluene And aromatic hydrocarbons such as xylene; esters such as ethyl acetate and butyl acetate; and halogenated hydrocarbons such as trichloroethylene, tetrachloroethylene and bromochloromethane, and one or a mixture of two or more thereof. The amount of the organic solvent is selected from the range of 20 to 200 parts by weight and used.

The ceramic green body of the present invention can be degreased and fired by a known method to produce a sintered body. For example, degreasing is generally performed in air or a nitrogen atmosphere, and the degreasing temperature is 300 to 100 depending on the ceramic powder, the binder and the atmosphere.
It is arbitrarily selected from the range of 0 ° C. Then, it is fired in an arbitrary temperature and an arbitrary atmosphere depending on the type of the ceramic powder. As an example, in the case of aluminum nitride,
An aluminum nitride sintered body can be obtained by firing at a temperature of 1700 to 1950 ° C. in a non-oxidizing atmosphere.

[0040]

The present invention improves the strength of the ceramic green body while maintaining the original thermal decomposability of the acrylic resin. Specifically, it is possible to mold with a binder amount as conventional as possible. In addition, it is possible to take advantage of the good thermal decomposability inherent in acrylic resin. As a result, it becomes possible to manufacture a high-quality ceramic sintered body that maximizes the original material properties of the ceramic with a good yield.

Among them, the ceramic green body of the present invention can be used as a co-firing substrate with a refractory metal such as tungsten, which needs degreasing and firing in a non-oxidizing atmosphere such as vacuum and nitrogen, a metal bonded substrate, a fine pattern and the like. It is preferably used for a substrate having a metallized surface.

Therefore, the ceramic green body of the present invention is an industrially extremely useful material for structural materials requiring high quality and electronic materials such as aluminum nitride.

[0043]

EXAMPLES The present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

Various physical properties in the following examples and comparative examples were measured by the following methods.

1) Specific surface area N ₂ was obtained by using "Flowsorb 2300" manufactured by Shimadzu Corporation.
It was determined by the BET method by adsorption.

2) Average Aggregate Particle Size It was determined by the centrifugal sedimentation method using "CAPA 500" manufactured by Horiba Ltd.

3) Amount of Impurities As for the cationic impurities, aluminum nitride powder was alkali-melted, neutralized with an acid, and then "ICPS-100" manufactured by Shimadzu Corporation.
The solution was quantified by ICP emission spectroscopy using "0".

The amount of impurity carbon was determined by burning aluminum nitride powder in an oxygen stream and using "EMIA-" manufactured by Horiba Ltd.
110 ”was used to quantify the amount of generated CO and CO ₂ gas.

The impurity oxygen content was generated by high temperature pyrolysis in a graphite crucible using aluminum nitride powder "EMGA-2800" manufactured by Horiba Ltd.
It was determined from the amount of O gas.

4) Mud viscosity Viscometer DVL type B made by Tokyo Keiki Co., Ltd. E was measured at 20 ° C. The thixotropic property was obtained by dividing the viscosity measured at a rotation speed of 1.5 rpm by the viscosity measured at 3 rpm.

5) Sheet Density (d) It was determined by measuring the size and weight of a sheet molded product punched into a predetermined shape.

6) Sheet Tensile Strength and Elongation Using "STROGRAPH M2" manufactured by Toyo Seiki Co., Ltd., a sheet tension rate of 10 mm / min was measured using a load cell of 2 kg under conditions of 25 ° C. and humidity of 60%. The average value of 5 times was used as the measured value. Test sample is ASTM D1
It was manufactured by punching with a 822 L type mold.

7) Press-Molded Body Density Using a mold of 30 mm, a press-molded body having a thickness of 5 mm was produced at a pressing pressure of 1.0 t / cm ² . The press-molded body density was determined from the dimensions and weight of the obtained press-molded body.

8) Sintered body density The density was determined by the Archimedes method using "High-precision specific gravity meter DH" manufactured by Toyo Seiki.

9) Thermal conductivity The thermal conductivity was measured by a laser flash method using a "thermal constant measuring device PS-7" manufactured by Rigaku Denki Co., Ltd. Thickness correction was performed using a calibration curve.

Example 1 Nylon balls with an iron core were placed in a nylon pot having an internal volume of 10 l, then 100 parts by weight of aluminum nitride powder shown in Table 1, 5 parts by weight of yttrium oxide, and 1 part by weight of tetraglycerin monooleate as a surfactant. Parts, and 36 parts by weight of toluene as a solvent were added to sufficiently perform the first ball mill mixing, and then poly (n) containing 4% of polyvinyl butyral previously as a binder was added to the mixture.
9 parts by weight of butyl methacrylate, 4 parts by weight of dibutyl phthalate as a plasticizer, 10 parts by weight of toluene as a solvent, and 5 parts by weight of butyl acetate were added, and a second ball mill mixing was performed to obtain a white mud. I got a ginger.

[0057]

[Table 1]

The so obtained slurry was desolvated and the viscosity was adjusted to 10,000 to 20000 cps, and then the viscosity of the obtained slurry was measured. After that, the sheet is formed by the doctor blade method and then at room temperature for 1 hour at 60 ° C.
It was dried for 2 hours at 100 ° C. for 1 hour to prepare a green sheet having a width of 20 cm and a thickness of 0.9 to 1.0 mm. The sheet density, sheet tensile strength and sheet elongation of the obtained green sheet were measured, and the results are shown in Table 2.

Next, the green sheet was punched into a predetermined shape with a 34 mm square die, and then the sheet was placed in nitrogen at 600 ° C. for 5 hours.
It was fired for an hour, then placed in a carbon crucible having an inner surface coated with boron nitride, and fired at 1800 ° C. for 5 hours in a nitrogen atmosphere. The density and thermal conductivity of the obtained sintered body were measured, and the results are shown in Table 2.

Comparative Example 1 Polyn-butyl methacrylate was used alone as a binder, and the sheet density was the same as in Example 1,
Other than adjusting the amount of toluene used the first time,
In the same manner as in Example 1, an aluminum nitride green sheet was obtained, a punched body was obtained, and a sintered body was obtained. The results are shown in Table 2.

Comparative Example 2 Aluminum nitride was used in the same manner as in Example 1 except that polyvinyl butyral was used as the binder and the amount of toluene used for the first time was adjusted so that the sheet density was the same as in Example 1. A green sheet was obtained, a punched body was obtained, and a sintered body was obtained. The results are shown in Table 2.

[0062]

[Table 2]

Example 2 An aluminum nitride green sheet was obtained and a punched body was obtained in the same manner as in Example 1 except that poly n-butyl methacrylate containing polyvinyl butyral in the amount shown in Table 3 was used. A sintered body was obtained. The results are shown in Table 3.

[0064]

[Table 3]

Example 3 An aluminum nitride green sheet was obtained in the same manner as in Example 1 except that poly n-butyl methacrylate containing 4% of polyvinyl butyral was used in the amount shown in Table 4, and a punched body was obtained. Then, a sintered body was obtained. Table 4 shows the results
It was shown to.

[0066]

[Table 4]

Example 4 Nylon balls with an iron core were placed in a nylon pot having an internal volume of 2 l, and then aluminum nitride powder 1 shown in Table 1 was used.
100 parts by weight of 00 parts by weight, 5 parts by weight of yttrium oxide, 1 part by weight of hexaglycerin monooleate, 3 parts by weight of poly-n-butyl methacrylate containing 4% of polyvinyl butyral in advance, and 100 parts by weight of toluene as a solvent were sufficiently added to the ball mill. After mixing, a white sludge was obtained.

The thus obtained mud was granulated by the spray dryer method, and the obtained granules were used to obtain 1.0
With a pressing pressure of t / cm ² , a press-molded body of 30 mm square and 5 mm thickness was prepared, and the density of the press-molded body was measured.
Then, it was baked in nitrogen at 600 ° C. for 5 hours, then put in a carbon crucible having an inner surface coated with boron nitride, and baked in a nitrogen atmosphere at 1800 ° C. for 5 hours. The density and thermal conductivity of the obtained sintered body were measured, and the results are shown in Table 5.

Comparative Example 3 An aluminum nitride press-molded body was obtained in the same manner as in Example 1 except that poly-n-butyl methacrylate was used alone as the binder, and a sintered body was obtained. Table 5 shows the results.

Comparative Example 4 An aluminum nitride press-molded body was obtained in the same manner as in Example 1 except that polyvinyl butyral was used as the binder to obtain a sintered body. Table 5 shows the results.

[0071]

[Table 5]

Claims (1)

[Claims] 1. A ceramic comprising 100 parts by weight of ceramic powder and 0.1 to 30 parts by weight of a binder composed of an acrylic resin and polyvinyl butyral, and the proportion of the polyvinyl butyral in the binder is 0.1 to 10% by weight. Green body.