JPH0656511A - Binder for producing inorganic sintered compact - Google Patents

Abstract

PURPOSE:To provide a binder for the production of an inorg. sintered compact giving a green compact excellent in compactibility and shape retentivity, causing easy decomposition and scattering in sintering especially even in a nonoxidizing atmosphere and not remaining as an undecomposed oxide in a sintered compact. CONSTITUTION:This binder for the production of an inorg. sintered compact is made of a methacrylate (co)polymer contg. >=60wt.% units of one or more kinds of methacrylates each having a substituent such as an alkyl, hydroxyl, alkoxy or epoxy group at a position other than a carbon atom at the 1-position of the carbon principal chain of a moiety corresponding to alcohol in the methacrylate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a binder for producing an inorganic sintered body, and particularly, it provides a green molded body having excellent formability and excellent shape-retaining property, and it is possible to obtain a green molded body under sintering conditions. The present invention relates to a binder that is easily decomposed and scattered even under firing and sintering conditions in an oxidizing atmosphere and does not remain as undecomposed carbide in the sintered body.

[0002]

2. Description of the Related Art The most widely practiced method for producing various sintered compacts is to mix inorganic powders such as alumina, silica, zirconia, mullite, silicon carbide and silicon nitride with an organic polymer binder. To obtain a green compact, which is fired to decompose and scatter the binder, and then the ceramic powder is sintered.

In this case, since firing / sintering is usually carried out in an oxidizing gas atmosphere such as air, the organic binder is thermally decomposed and scattered, and undecomposed / undispersed carbide remains inside the sintered body. In addition, since the inorganic fine powder is sintered after the binder is decomposed and scattered, it is possible to obtain a dense sintered body with almost no void defects.

However, depending on the type of the inorganic powder or the use of the sintered body, it may be necessary to perform firing / sintering in a non-oxidizing atmosphere. For example, if the inorganic powder contains nitrides, carbides, metals, etc.,
When firing / sintering in an oxidizing atmosphere, these are oxidized and lose their properties as a non-oxide sintered body, so firing / sintering must be performed in a non-oxidizing atmosphere. In addition, we want to form a film made of non-oxide material on the surface of compacts such as ceramics and ceramic green compacts, and sinter and sinter the ceramic green compact while keeping the non-oxide material coating in the non-oxidized state. In such a case, it is also necessary to perform firing / sintering in a non-oxidizing atmosphere. However, when a normal green molded body molded using an organic polymer binder is heated in a non-oxidizing atmosphere, some of the organic polymer binder does not decompose and scatter, and it tends to remain as carbides in the sintered body. Cracks, warpage and swelling occur in the molded body during the binding process, and a large amount of carbide remains in the sintered body, which lowers the compactness, weakens the sintered body, and lowers electrical insulation. Or gray ~
It causes various problems such as coloring in black.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and its purpose is not only when firing and sintering are performed in an oxidizing atmosphere, but also when non-oxidizing is performed. Even if fired / sintered in an atmosphere, it easily decomposes /
It does not scatter and remain as carbide in the sintered body,
Moreover, it is an object of the present invention to provide a binder for producing an inorganic sintered body, which can effectively function as a binder in the green molding process and can exhibit excellent moldability, shape retention and handleability.

[0006]

The composition of the binder according to the present invention, which has been able to achieve the above object, is one of the carbon main chains of the alcohol-corresponding portion of methacrylic acid ester.
Containing at least one methacrylic acid ester unit having a substituent at a position excluding the carbon atom at the position, and when the substituent is an alkyl group, the total carbon number of the alcohol equivalent part is 5 or more. The gist is that it is composed of a methacrylic acid ester (co) polymer in an amount of 60% by weight or more.

In the above, those in which the substituent is an alkyl group, a hydroxyl group, an alkoxy group or an epoxy group are more easily decomposed and scattered in the debinding step under a non-oxidizing atmosphere. Further, if a methacrylic acid ester-based (co) polymer containing 50% by weight or more of methacrylic acid ester units in which the number of carbon atoms in the alcohol portion of the methacrylic acid ester is 5 or more is selected, decomposition / decomposition in a non-oxidizing atmosphere is achieved.
It is possible to obtain a binder which is more excellent in moldability, shape retention and handleability as well as scattering property.

The methacrylic acid ester-based (co) polymer has an acid value of 0.1 to 20 and / or 0.1 for the purpose of ensuring the dispersibility and moldability of the inorganic powder during the production of a green compact as described below. Those having a hydroxyl value in the range of 60 to 60 are preferable, and the methacrylic acid ester-based (co)
When the polymer having a number average molecular weight in the range of 10,000 to 100,000 is used, the green moldability and shape retention and the decomposition / scattering property during sintering can be further improved.

[0009]

As described above, the present invention specifies the structure of the alcohol-corresponding portion of the methacrylic acid ester and the mixing ratio of the methacrylic acid ester unit, and these setting criteria include the inorganic powder. While ensuring the formability, shape retention and handleability that are the originally required properties as a binder for green molding, it also ensures properties that can be easily decomposed and scattered even during debinding in a non-oxidizing atmosphere. It is set for. Hereinafter, the reason for setting each constituent element will be described in detail.

First, the reason why the methacrylic acid ester having a substituent at the position excluding the carbon atom at the 1-position of the carbon main chain of the alcohol equivalent portion in the methacrylic acid ester is selected as the main monomer unit is that these are included as the monomer units ( The co) polymer exhibits a better depolymerizability than a methacrylic acid ester having a substituent at the 1-position carbon atom of an alcohol-corresponding portion such as methylmethacrylate, ethylmethacrylate or tert-butylmethacrylate, and has a non-oxidizing atmosphere. This is because even when heated under oxidization, depolymerization easily occurs and scatters / scatters, and it is difficult for carbide to remain in the sintered body.

The reason for this is not clear, but if there is a substituent at the 1-position carbon atom of the carbon main chain of the alcohol equivalent part,
Due to the stability of the radicals generated when the ester moiety is decomposed and cleaved, the ester moiety is apt to be decomposed and cleaved, and COOs produced by the decomposition and cleavage of the ester part are easily bonded and crosslinked during depolymerization. It is presumed that the thermal decomposability deteriorates.

On the other hand, in the case where there is a substituent at the carbon position excluding the carbon at the 1-position of the alcohol equivalent part, the radical generated in the polymethacrylic acid ester main chain by depolymerization has a position of the substituent of the ester part. It is supposed that the radicals are sterically protected because they are close to each other, and as a result of inhibiting the bonding and cross-linking of the radicals, the depolymerization of the polymethacrylate main chain is promoted and the thermal decomposability is improved. It is expected that the effect will be remarkably exhibited when there is a substituent at the 2-position carbon position of the alcohol equivalent part. Here, the carbon at the 1-position of the alcohol-corresponding portion is carbon bonded to oxygen in the methacrylic acid-corresponding portion.

In the present invention, a methacrylic acid ester unit having a substituent at a carbon position excluding the carbon at the 1-position of the main chain of the alcohol-corresponding portion of the methacrylic acid ester means methacrylic acid and a C2-C20 side chain or a substituent. Is an ester with an alcohol having.

Examples of those having an alkyl group as a substituent include an alkyl group having a carbon main chain of 5 or more,
For example, 2-methylbutyl methacrylate, 2-ethylbutyl methacrylate, 3-methylbutyl methacrylate, 2-methylpentyl methacrylate, 3-methylpentyl methacrylate, 4-methylpentyl methacrylate, 2-ethylhexyl methacrylate, 2,4,6
-Trimethylheptyl methacrylate, isooctyl methacrylate, isodecyl methacrylate, 2-heptyl undecyl methacrylate, isolauryl methacrylate, isostearyl methacrylate and the like are exemplified. Particularly preferred among these are those in which the position of the substituent is on the 2-position carbon.

Those having a hydroxyl group as a substituent include 2-
Hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 3-hydroxypropyl methacrylate, 2-hydroxybutyl methacrylate, 3-hydroxybutyl methacrylate, 4-hydroxybutyl methacrylate, 2-hydroxy-3-methylbutyl methacrylate, 2-hydroxy-3, Examples thereof include 3-dimethylbutyl methacrylate, trimethylolpropane monomethacrylate, 2-hydroxy-3-phenoxypropyl methacrylate and glycerol monomethacrylate.

Further, those having an alkoxy group as a substituent include 2-methoxyethyl methacrylate and 2
-Ethoxyethyl methacrylate, 2-butoxyethyl methacrylate, 3-methoxypropyl methacrylate, 3-methoxybutyl methacrylate, methoxydiethylene glycol methacrylate, ethoxydiethylene glycol methacrylate, polyethylene glycol monomethacrylate, polypropylene glycol monomethacrylate, 2-phenoxyethyl methacrylate and the like. .

Examples of those having an epoxy group as a substituent include glycidyl methacrylate, tetrahydrofurfuryl methacrylate (2,5-epoxypentyl methacrylate), and 2,3-epoxybutyl methacrylate. Examples of those having a substituent other than the above include benzyl methacrylate, 2-phenylethyl methacrylate, dimethylaminoethyl methacrylate and the like.

To achieve the object of the present invention, at least one selected from the group consisting of the above-mentioned methacrylic acid esters accounts for 60% by weight or more, more preferably 80% by weight or more of the total monomer units. Ester-based (co) polymers must be used, and if these requirements are not satisfied, carbides tend to remain under the heating conditions of a non-oxidizing atmosphere, and the object of the present invention cannot be achieved. Therefore, in the present invention, it is preferable that all or most of the monomer units are the above-mentioned methacrylate units, and they may be a homopolymer or a copolymer using two or more kinds of monomers. Absent. However, among the above-mentioned monomer units, those mainly composed of a methacrylic acid ester unit in which the total carbon number of the alcohol equivalent portion is 5 or more show particularly excellent depolymerizability, so the ratio of the methacrylic acid ester unit satisfying these requirements should be controlled. It is preferably 50% by weight or more, more preferably 60% by weight or more.

In the present invention, as long as the content of one or more methacrylic acid ester units having a substituent at the position excluding the carbon atom at the 1-position of the carbon main chain of the alcohol equivalent portion in the methacrylic acid ester is satisfied, It is possible to copolymerize at most 40% by weight of all monomer units with one or more vinyl monomers copolymerizable with other methacrylates.

Examples of such copolymerizable monomers include methyl (meth) acrylate, ethyl (meth) acrylate,
Propyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, sec
-Butyl (meth) acrylate, tert-butyl (meth) acrylate, 1,2-dimethylbutyl (meth) acrylate, 1,3-dimethylbutyl (meth) acrylate, 2-methoxyethyl acrylate, 2-ethoxyethyl acrylate, 2 -Ethylhexyl acrylate, isooctyl acrylate, isodecyl acrylate, lauryl (meth) acrylate, isolauryl acrylate, stearyl (meth) acrylate, isostearyl acrylate, 2-hydroxyethyl acrylate, 1-methyl-2-hydroxyethyl (meth) acrylate , 2-hydroxypropyl acrylate, 3-hydroxypropyl acrylate, 2-hydroxybutyl acrylate, glycerol monoacrylate, trimethylolpropane (Meth) acrylate monomers such as acrylate, polyethylene glycol monoacrylate, polypropylene glycol monoacrylate, cyclohexyl (meth) acrylate, cycloheptyl (meth) acrylate, cyclooctyl (meth) acrylate, dimethylamino (meth) acrylate; acrylic acid, Copolymerizable unsaturated carboxylic acids such as maleic acid half-esters such as methacrylic acid, maleic acid, itaconic acid, citraconic acid, monoisopropyl maleate; styrene,
Examples thereof include styrene-based monomers such as α-methylstyrene, β-methylstyrene, α-ethylstyrene, β-ethylstyrene, and vinylstyrene, and these may be used in combination of two or more if necessary.

Of these, the styrene-based monomer is excellent in depolymerizability and has an effect of lowering the decomposition temperature of the methacrylic acid ester-based (co) polymer, so that it can be added up to 40% by weight. Of the styrene-based monomers, α-methylstyrene is particularly preferable.

Further, the acrylic ester type monomer is
It has the effect of adjusting the glass transition temperature to enhance the moldability and handleability of the green, such as propyl acrylate,
Although it is possible to use a small amount of butyl acrylate, 2-hydroxy acrylate, etc., since the acrylic acid ester-based copolymer is inferior in depolymerizability to the methacrylic acid ester-based copolymer, its addition amount is 10% by weight. % Or less, preferably 5% by weight or less.

Further, (meth) acrylonitrile, acrylamide, alkylacrylamide, vinyl acetate, vinyl chloride and the like can be copolymerized, but when a large amount of these monomers are copolymerized, the thermal decomposition property of the resulting copolymer is poor. Therefore, even if it is used in combination as a monomer unit, it is necessary to reduce the amount to a small amount.

A monomer having a hydroxyl group as a substituent or a copolymerizable unsaturated carboxylic acid imparts an appropriate hydroxyl value or acid value to a methacrylic acid ester (co) polymer to enhance the dispersibility and dispersion stability of the inorganic powder. It has a function and is preferably used for the purpose of improving green moldability, strength and handleability. The preferred hydroxyl value and acid value of the (co) polymer vary depending on the type of the inorganic powder, polarity, acidity, basicity, acid amount, etc., but the hydroxyl value is 0.1-60 and /
Alternatively, it is preferable to adjust the acid value in the range of 0.1 to 20. The acid value is more effective than the hydroxyl value, and if the acid value is too high, the decomposition / scattering property of the methacrylic acid ester-based (co) polymer during firing tends to be poor. It is better to adjust the range to 1-10. Further, when the hydroxyl value exceeds 60, green moldability,
On the contrary, the strength and handleability may decrease.

The polymerization method for obtaining the methacrylic acid ester (co) polymer according to the present invention is not particularly limited, but the most general method is a radical such as peroxide, hydroperoxide or azobisisobutyronitrile. A usual polymerization method such as suspension polymerization, solution polymerization or emulsion polymerization is employed in the presence of a polymerization initiator, and the reaction is usually carried out at 10 to 150 ° C. for several minutes to several hours. In this case, if necessary, a chain transfer agent can be further added during the polymerization reaction. The content of the obtained copolymer is 90 to 1,000,000, and the content of the copolymer is 90 to 1,000,000.
%, And the content ratio of the copolymer having a molecular weight of 150,000 or less and the copolymer having a molecular weight of more than 150,000 in the above molecular weight range is preferably 1/1 to 9/1 by weight. . Further, it is preferable to use those having a number average molecular weight in the range of 10,000 to 100,000.

(Molecular weight measuring method) Measuring apparatus: Gel permeation chromatography "M-410" manufactured by WATERS, Inc. Detector: Differential refractometer Used column: Ultrastyra gel (7.
8 mmφ × 300 mmL) × 4 pieces Standard material: polystyrene Measurement conditions: Flow rate 1 cc / min (THF) Temperature 40 ° C

In addition to specifying the content of those having a specific molecular weight range, the content ratio of the low molecular weight side copolymer and the high molecular weight copolymer is specified based on the molecular weight range of 150,000 within the molecular weight range. However, these setting standards ensure that the original required properties of a green molding binder containing inorganic powder, such as moldability and shape retention, are easily decomposed and scattered even in debinding in a non-oxidizing atmosphere. This is a preferable requirement for ensuring the properties that can be achieved.

When the ratio of the low molecular weight copolymer and the high molecular weight copolymer outside the above molecular weight range exceeds 10%,
When the amount of the low molecular weight copolymer is too large, the performance as a binder becomes insufficient, and it becomes difficult to obtain satisfactory green moldability, shape retention and handleability. Decomposition / scatterability at the time of binder becomes poor, and the amount of carbides remaining in the sintered body becomes so large that it cannot be ignored.

Even if the content of the polymer within the above molecular weight range satisfies the above requirements, if the content ratio of the low molecular weight side copolymer exceeds the above range based on the molecular weight of 150,000. , Green molded body, shape retention and handleability are deteriorated, while when the content ratio of the high molecular weight side copolymer exceeds the above range, the residual amount as a carbide in the sintered body tends to increase. Come out.

The kind of the inorganic powder used in combination with the binder made of the methacrylic acid (co) polymer is not limited at all, and oxides such as alumina, titania, silica, zirconia, zircon, mullite and cordierite are used. , Sialon, barium titanate, lead zirconate titanate, and other complex oxides, and borosilicate glass, crystallized glass, and other glassy inorganic powders can be fired and sintered under an oxidizing atmosphere without any problem. At least 1
It is of course possible to use as a binder for one or more kinds of oxide-based inorganic powders, but the feature of the binder of the present invention is most effectively exhibited when calcination and sintering are carried out in an oxidizing atmosphere. Inorganic powders that cause aluminum, such as aluminum nitride, silicon nitride, boron nitride, and other nitrides; silicon carbide, tungsten carbide, boron carbide, and other carbides; and iron, stainless steel, nichrome, titanium aluminum, and other metals and alloys. One or more non-oxide powders of Although firing / sintering in a non-oxidizing atmosphere varies greatly depending on the conditions, it is preferable that the oxygen concentration is usually 1% or less, more preferably 1000 ppm or less, and further preferably 100 ppm or less. Depending on the type of inorganic powder, even if a small amount of oxygen is present in the firing / sintering atmosphere, it will not be substantially adversely affected, so when using it in combination with such an inorganic powder, firing -The sintering atmosphere may contain a small amount of oxygen, hydrogen, water, etc.

The method for producing an inorganic sintered compact using the binder of the present invention is not particularly special and may be carried out according to a conventional method, but if it is exemplified as a general method, first, the inorganic powder as described above is prepared. The mixture is uniformly kneaded with the binder of the present invention and a suitable dispersion medium (preferably an organic solvent such as acetone, methyl ethyl ketone, methanol, ethanol, isopropanol, butanol, toluene, xylene, ethyl acetate, or a mixture thereof). The amount of the binder used may be appropriately determined, but in general, the inorganic powder 10 is used in consideration of the moldability, the shape retention and handleability of the green, the decomposition / scattering property at the time of debinding.
The range is 1 to 40 parts by weight, preferably 3 to 0 parts by weight.
-30 parts by weight. At this time, if necessary, a dispersant (polyhydric alcohol ester such as glycerin or sorbitan, polycarboxylic acid, or amine dispersant), a plasticizer (polyethylene glycol, phthalic acid) for imparting flexibility to the green molded body. It is also possible to add an appropriate amount of dibutyl, phthalic acid ester such as dioctyl phthalate, etc.) or a sintering aid (glass powder, clay, talc, magnesia, calcia, yttria, ceria, etc.).

Next, if necessary, it is defoamed and then molded into an arbitrary shape to obtain a green molded body. There is no limitation on the molding method at all, and any conventionally known method such as press molding, extrusion molding, injection molding, sheet molding with a doctor blade can be adopted, but the binder of the present invention has a particularly excellent effect on sheet molding. Exert. Next, this green molded body or, if necessary, the secondary molded green molded body is heat-treated to volatilize and remove the dispersion medium and decompose the binder.
Scattering and debindering are performed by firing / sintering, but if the heat treatment temperature is raised to the firing / sintering temperature all at once, the molded body is likely to have cracks or void defects, so preferably stepwise or continuous. It is desirable that the temperature be gradually raised to complete the decomposition and scattering of the binder in a relatively low temperature range before sintering.

[0033]

EFFECTS OF THE INVENTION The present invention is constituted as described above, and has the property of easily decomposing / scattering without being carbonized even when heated in a non-oxidizing atmosphere while retaining various functions as a binder. Therefore, even when a sintered compact made of an inorganic powder that is particularly susceptible to oxidation is obtained, there is no risk that it will remain in the sintered body as a carbide to deteriorate the appearance and cause a decrease in the sintered density. In addition, depending on the type of inorganic powder used, it is necessary to give the sintered compact various properties such as insulation, conductivity, and magnetic properties, and these required properties may be significantly impaired by the residue of carbide. Such problems can be avoided by using the binder of the invention. Furthermore, since the binder of the present invention easily decomposes and scatters even under firing / sintering conditions in an oxidizing atmosphere,
It can also be used as a binder for inorganic powders in which the binder removal step and the sintering step are performed in an oxidizing atmosphere without any problem.

[0034]

EXAMPLES Hereinafter, the present invention will be specifically described by way of examples. However, the present invention is not limited by the following examples, and the present invention is appropriately modified and implemented in accordance with the spirit of the preceding and following description. All that is included in the technical scope of the present invention.

Examples 1 to 12 and Comparative Examples 1 to 8 In a separable flask equipped with a stirrer, a thermometer, a nitrogen introduction tube, a monomer dropping funnel and a polymerization initiator dropping funnel, 60 parts by weight of toluene and 2- 20 parts by weight of propanol was added, and nitrogen was blown into the flask from the nitrogen introduction tube to replace the inside of the flask with nitrogen. On the other hand, the monomer dropping funnel is charged with 100 parts by weight of the monomers shown in Table 1, and the polymerization initiator dropping funnel is charged with a solution of 30 parts by weight of toluene and 1.8 parts by weight of azobisisobutyronitrile. . Next, the temperature of the flask was raised, the monomer and the polymerization initiator were added dropwise over 2 hours with stirring, the stirring was continued for 2 hours, the internal temperature was raised to 80 ° C., the mixture was heated and stirred for 2 hours, and then the temperature was lowered by cooling. A methacrylic acid ester-based (co) polymer was obtained.

The molecular weight distribution of each of the obtained copolymers was measured by the above-mentioned method, and the content rate of those having a molecular weight of 1,000 to 1,000,000, the molecular weight (1,000 to 150,000) / (150,000 to 100).
The weight ratio and the number average molecular weight are shown in Table 1, and the acid value is also shown. Further, a predetermined amount of each copolymer was placed in a platinum crucible, heated to 600 ° C. in a nitrogen stream, and the amount of residual carbon was measured when the copolymer was kept at the same temperature for 1 hour, and the presence or absence thereof is also shown in Table 1.

Further, the thermal decomposability of each of the obtained copolymers was measured by a thermobalance (measurement condition: temperature was raised to 600 ° C. at a heating rate of 4 ° C./min in a nitrogen stream of 0.1 liter / min). , And the respective thermal decomposition curves were obtained. As a representative example of the results, the thermal decomposition curves of Example 1 and Comparative Example 1 are shown in FIG.

The symbols in Table 1 have the following meanings. MAA: Methacrylic acid MMA: Methyl methacrylate EMA: Ethyl methacrylate iBMA: Isobutyl methacrylate tBMA: tert-Butyl methacrylate 2MPMA: 2-Methylpentyl methacrylate 2EHMA: 2-Ethylhexyl methacrylate TMHpMA: 2,4,6-Trimethylheptyl methacrylate LMA: Lauryl methacrylate HEMA: 2-hydroxyethyl methacrylate 2BOEMA: 2-butoxyethyl methacrylate THFMA: tetrahydrofurfuryl methacrylate αMSt: α-methylstyrene

[0039]

[Table 1]

Test Example 1 100 parts by weight of a mixed powder of 45% by weight of aluminum oxide powder having an average particle diameter of 2 μm and 55% by weight of borosilicate glass powder having an average particle diameter of 5 μm, and the methacrylic acid ester-based powder obtained in Example 1 12 parts by weight of polymer as a binder, 1 part by weight of dioctyl phthalate as a plasticizer, toluene / methyl ethyl ketone (1/1) mixed solvent 4 as a dispersion medium
After mixing 0 parts by weight to make a slurry, an alumina / glass green sheet having a thickness of 0.23 mm was obtained by a doctor blade method.

This green sheet was 550 in a nitrogen stream.
The temperature was gradually raised to 0 ° C, the temperature was maintained for 2 hours to remove the binder, and then the temperature was maintained at 900 ° C for 1 hour for firing and sintering. The residual carbon content of the obtained sintered sheet was extremely small at 150 ppm, and the bending strength was excellent at 1700 kgf / cm ² . In addition, this green sheet 5
The temperature was raised to 00 ° C., the temperature was maintained for 1 hour to remove the binder, and then the temperature was maintained at 900 ° C. for 1 hour for firing and sintering.
The residual carbon amount of the obtained sintered sheet was 10 ppm or less, and the bending strength was 1700 kgf / cm ² .

Test Example 2 100 parts by weight of the mixed powder of aluminum oxide powder and borosilicate glass powder used in Test Example 1 and the methacrylic acid ester copolymer obtained in Example 8 as a binder were used.
After mixing 5 parts by weight, 4 parts by weight of dioctyl phthalate as a plasticizer, and 50 parts by weight of a mixed solvent of toluene / ethyl acetate (3/2) as a dispersion medium to form a slurry, a doctor blade method is used to form alumina having a thickness of 0.23 mm. / A glass green sheet was obtained.

This green sheet was 550 in a nitrogen stream.
The temperature was gradually raised to 0 ° C, the temperature was maintained for 2 hours to remove the binder, and then the temperature was maintained at 900 ° C for 1 hour for firing and sintering. The residual carbon content of the obtained sintered sheet was extremely low at 120 ppm, and the bending strength was 1800 kgf / cm ² , which was excellent. In addition, this green sheet is 60
The temperature was raised to 0 ° C., the temperature was maintained for 1 hour to remove the binder, and then the temperature was maintained at 900 ° C. for 1 hour for firing and sintering. The obtained sintered sheet had a residual carbon content of 20 ppm or less and a bending strength of 1800 kgf / cm ² .

Test Example 3 100 parts by weight of a mixed powder of 97% by weight of aluminum nitride powder having an average particle diameter of 9 μm and 3% by weight of yttrium oxide powder as a sintering aid was added to the methacrylate ester-based copolymer obtained in Example 11. The combined product was mixed as a binder with 3 parts by weight and as a solvent with 40 parts by weight of methyl ethyl ketone as a slurry. The obtained slurry is dried, and the dried powder is dried to a diameter of 10
A block-shaped green molded body was produced by press-molding into a cylindrical shape having a size of 10 mm and a height of 10 mm.

This green compact was subjected to 60 in a nitrogen atmosphere.
After heating at 0 ° C for 2 hours to remove the binder, another 18
The temperature was raised to 00 ° C. and the temperature was maintained for 6 hours, followed by firing and sintering to obtain an aluminum sintered compact. The molded product had a relative density of 99.1%, a volume resistance of 9 × 10 ¹⁴ Ω · cm, a residual carbon content of 100 ppm and a very small thermal conductivity of 170 W / m · k. there were.

Comparative Test Example 1 Alumina was prepared in the same manner as in Test Example 1 except that 12 parts by weight of the methacrylic acid ester-based copolymer obtained in Comparative Example 1 was used as a binder and 4 parts by weight of dioctyl phthalate was used as a plasticizer. / A glass green sheet was formed, and the binder was removed in a nitrogen stream, and firing and sintering were performed to obtain a sintered sheet. The residual carbon content of this sheet was 2000 ppm, and the bending strength was 1000 kgf / cm ² or less, which was very weak.

Comparative Test Example 2 Alumina / glass green sheet was molded and in a nitrogen stream in the same manner as in Test Example 2 except that 15 parts by weight of the acrylic ester copolymer obtained in Comparative Example 6 was used as a binder. The binder was removed from the above and baked and sintered to obtain a sintered sheet. The residual carbon content of this sheet is 1200 pp
At m, this sheet has a gray color and a bending strength of 11
It was 00 kgf / cm ² .

Comparative Test Example 3 An aluminum nitride sintered compact was obtained in the same manner as in Test Example 3 except that the methacrylate copolymer obtained in Comparative Example 2 was used as a binder in an amount of 5 parts by weight. The molded product had a relative density of 97.6% and a volume resistance of 6 × 10 ¹² Ω · cm.

[Brief description of drawings]

FIG. 1 is a thermal decomposition curve of a binder obtained in Example 1 and Comparative Example 1.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takahiro Aoyama 5-8 Nishimitabicho, Suita City, Osaka Prefecture Nippon Shokubai Suita Factory

Claims (2)

[Claims] 1. A methacrylic acid ester having a substituent at a position excluding the carbon atom at the 1-position of the carbon main chain of the alcohol-corresponding portion, and when the substituent is an alkyl group, all carbons of the alcohol-corresponding portion. The content of one or more methacrylic acid ester units whose number is 5 or more is 60% by weight.
A binder for producing an inorganic sintered body, comprising the methacrylic acid ester-based (co) polymer described above. 2. The binder for producing an inorganic sintered body according to claim 1, wherein the substituent is an alkyl group, a hydroxyl group, an alkoxy group or an epoxy group.